| 1. |
- Malmgren, Linnea, et al.
(author)
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The complexity of kidney disease and diagnosing it - Cystatin C, selective glomerular hypofiltration syndromes and proteome regulation.
- 2023
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In: Journal of Internal Medicine. - : John Wiley & Sons. - 0954-6820 .- 1365-2796. ; 293:3, s. 293-308
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Journal article (peer-reviewed)abstract
- Estimation of kidney function is often part of daily clinical practice, mostly done by using the endogenous GFR-markers creatinine or cystatin C. A recommendation to use both markers in parallel in 2010 has resulted in new knowledge concerning the pathophysiology of kidney disorders by identification of a new set of kidney disorders, selective glomerular hypofiltration syndromes. These syndromes, connected to strong increases in mortality and morbidity, are characterised by a selective reduction in the glomerular filtration of 5-30 kDa molecules, such as cystatin C, compared to the filtration of small molecules < 1kDa dominating the glomerular filtrate e.g., water, urea, creatinine. At least two types of such disorders, shrunken or elongated pore syndrome, are possible according to the pore model for glomerular filtration. Selective glomerular hypofiltration syndromes are prevalent in investigated populations, and patients with these syndromes often display normal measured GFR or creatinine-based GFR-estimates. The syndromes are characterised by proteomic changes promoting the development of atherosclerosis, indicating antibodies and specific receptor-blocking substances as possible new treatment modalities. Presently, the KDIGO guidelines for diagnosing kidney disorders do not recommend cystatin C as a general marker of kidney function and will therefore not allow the identification of a considerable number of patients with selective glomerular hypofiltration syndromes. Furthermore, as cystatin C is uninfluenced by muscle mass, diet or variations in tubular secretion and cystatin C-based GFR-estimation equations do not require controversial race or sex terms, it is obvious that cystatin C should be a part of future KDIGO guidelines.
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| 2. |
- Grubb, Anders, et al.
(author)
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Generation of a new cystatin C-based estimating equation for glomerular filtration rate by use of 7 assays standardized to the international calibrator
- 2014
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In: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 60:7, s. 974-986
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Journal article (peer-reviewed)abstract
- BACKGROUND:Many different cystatin C-based equations exist for estimating glomerular filtration rate. Major reasons for this are the previous lack of an international cystatin C calibrator and the nonequivalence of results from different cystatin C assays.METHODS:Use of the recently introduced certified reference material, ERM-DA471/IFCC, and further work to achieve high agreement and equivalence of 7 commercially available cystatin C assays allowed a substantial decrease of the CV of the assays, as defined by their performance in an external quality assessment for clinical laboratory investigations. By use of 2 of these assays and a population of 4690 subjects, with large subpopulations of children and Asian and Caucasian adults, with their GFR determined by either renal or plasma inulin clearance or plasma iohexol clearance, we attempted to produce a virtually assay-independent simple cystatin C-based equation for estimation of GFR.RESULTS:We developed a simple cystatin C-based equation for estimation of GFR comprising only 2 variables, cystatin C concentration and age. No terms for race and sex are required for optimal diagnostic performance. The equation, [Formula: see text] is also biologically oriented, with 1 term for the theoretical renal clearance of small molecules and 1 constant for extrarenal clearance of cystatin C.CONCLUSIONS:A virtually assay-independent simple cystatin C-based and biologically oriented equation for estimation of GFR, without terms for sex and race, was produced.
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| 3. |
- Sigurjonsson, Johann, et al.
(author)
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A study of size-selective renal elimination using a novel human model
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In: Scandinavian Journal of Clinical & Laboratory Investigation. - 1502-7686. ; , s. 1-6
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Journal article (peer-reviewed)abstract
- The recently discovered selective glomerular hypofiltration syndromes have increased interest in the actual elimination of molecules in the human kidney. In the present study, a novel human model was introduced to directly measure the single-pass renal elimination of molecules of increasing size. Plasma concentrations of urea, creatinine, C-peptide, insulin, pro-BNP, β2-microglobulin, cystatin C, troponin-T, orosomucoid, albumin, and IgG were analysed in arterial and renal venous blood from 45 patientsundergoing Transcatheter Aortic Valve Implantation (TA VI). The renal elimination ratio (RER) was calculated as the arteriovenous concentration difference divided by the arterial concentration. Estimated glomerular filtration rate (eGFR) was calculated by the CKD-EPI equations for both creatinine and cystatin C. Creatinine (0.11 kDa) showed the highest RER (21.0 ± 6.3%). With increasing molecular size, the RER gradually decreased, where the RER of cystatin C (13 kDa) was 14.4 ± 5.3% and troponin-T (36 kDa) was 11.3 ± 4.6%. The renal elimination threshold was found between 36 and 44 kDa as the RER of orosomucoid (44 kDa) was −0.2 ± 4.7%. The RER of creatinine and cystatin C showed a significant and moderate positive linear relationship with eGFR (r = 0.48 and 0.40). In conclusion, a novel human model was employed to demonstrate a decline in renal elimination with increasing molecularsize. Moreover, RERs of creatinine and cystatin C were found to correlate with eGFR, suggesting the potential of this model to study selective glomerular hypofiltration syndromes.
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| 4. |
- Balbin, M, et al.
(author)
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Determination of allotypes G1m(f) and G1m(z) at the genomic level by subclass specific amplification of DNA and use of allele specific probes
- 1991
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In: Experimental and Clinical Immunogenetics. - 0254-9670. ; 8:2, s. 88-95
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Journal article (peer-reviewed)abstract
- Two oligonucleotide primers were used for selective enzymatic amplification of a DNA segment encoding a major portion of the first constant region domain (CH1) of the human IgG1 heavy chain. The selective amplification was confirmed by use of subclass-specific oligonucleotide probes. Two 15-mer oligonucleotides, hybridizing with the alleles for the allotypes G1m(f) and (z), respectively, could then be used for determination at the genomic level of these two truly allelic allotypes. Serum and DNA samples from 12 individuals, one of them with a considerable amount of anti-Gm(f) antibodies, were used for allotype assignment by classical serological methods and by the new method operating at the genomic level. The resulting classifications agreed completely, demonstrating the reliability of the new method.
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| 5. |
- Balbin, Milagros, et al.
(author)
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Structural and functional characterization of two allelic variants of human cystatin D sharing a characteristic inhibition spectrum against mammalian cysteine proteinases
- 1994
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In: Journal of Biological Chemistry. - 1083-351X. ; 269:37, s. 23156-23162
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Journal article (peer-reviewed)abstract
- Human cystatin D is a novel member of the cystatin superfamily of cysteine proteinase inhibitors present in saliva and tears. Two alleles of the cystatin D gene (CST5), encoding protein variants with either Cys or Arg as residue 26 in their 122-residue polypeptide chains, are present in the population. Expression of the two alleles was investigated by immunochemical analyses of the secreted cystatin D in saliva from individuals homozygous for each of the two alleles, with results demonstrating that both are expressed at similar levels. The inhibitory characteristics of the two cystatin D variants were studied, by determination of dissociation equilibrium constants (Ki) for their complexes with papain and with the mammalian cysteine proteinases, cathepsins B, H, L, and S. The results demonstrate that 1) cystatin D has a characteristic inhibition profile since it does not inhibit cathepsin B (Ki > 1 microM), and when compared to cystatin C and all other known cystatins it is a much poorer inhibitor of cathepsin L (mean Ki 25 nM) but binds cathepsin H and S relatively tightly (mean Ki values of 8.5 and 0.24 nM, respectively); and 2) the inhibitory activities of the two cystatin D variants are not significantly different, demonstrating that the presence of an extra cysteine residue in the cystatin D molecule affects neither the stability nor the functional activity of the inhibitor, thus explaining the widespread distribution of the Cys26-cystatin D encoding allele in the population. The inhibitory properties displayed by cystatin D suggest that it has a function in saliva as inhibitor of either endogenous or exogenous enzymes with cathepsin S- or H-like properties.
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| 6. |
- Björk, Jonas, et al.
(author)
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A novel method for creatinine adjustment makes the revised Lund-Malmö GFR estimating equation applicable in children
- 2020
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In: Scandinavian Journal of Clinical and Laboratory Investigation. - : Informa UK Limited. - 0036-5513 .- 1502-7686. ; 80:6, s. 456-463
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Journal article (peer-reviewed)abstract
- The aim of this study was to establish creatinine growth curves separately for males and females that can be used to adjust childhood levels of serum creatinine to corresponding adult levels. Linear regression with fractional polynomials of age as independent variable was used to construct creatinine growth curves for a reference cohort (n = 83,157 samples from Belgium and Sweden, age 2-40 years). Adjusted creatinine obtained from the growth curves was used to improve accuracy of estimated glomerular filtration rate (eGFR) based on the Lund-Malmö revised (LMR) equation in children. The LMR equation based on creatinine values adjusted to age 18 years was validated against measured GFR (mGFR) in a separate cohort of 4005 children from four different European countries. Validation metrics included median bias, precision, and accuracy expressed as percentage of estimates within ±30% (P30) of mGFR. Remarkable improvements in bias and accuracy were observed; P30 increased from 56% to 74% after creatinine adjustments in children with mGFR <75 mL/min/1.73 m2 (n = 932), while P30 was relatively unchanged (89-90%) at mGFR ≥75 mL/min/1.73 m2 (n = 3073). The suggested approach with adjusted creatinine makes LMR applicable in children irrespective of their renal function.
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| 7. |
- Björk, Jonas, et al.
(author)
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Accuracy of GFR estimating equations combining standardized cystatin C and creatinine assays: a cross-sectional study in Sweden
- 2015
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In: Clinical Chemistry and Laboratory Medicine. - : Walter de Gruyter GmbH. - 1434-6621 .- 1437-4331. ; 53:3, s. 403-414
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Journal article (peer-reviewed)abstract
- Background: The recently established international cystatin C calibrator makes it possible to develop non-laboratory specific glomerular filtration rate (GFR) estimating (eGFR) equations. This study compares the performance of the arithmetic mean of the revised Lund-Malmo creatinine and CAPA cystatin C equations (MEAN(LM-REV+CAPA)), the arithmetic mean of the Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI) creatinine and cystatin C equations (MEAN(CKD-EPI)), and the composite CKD-EPI equation (CKD-EPICREA+CYSC) with the corresponding single marker equations using internationally standardized calibrators for both cystatin C and creatinine. Methods: The study included 1200 examinations in 1112 adult Swedish patients referred for measurement of GFR (mGFR) 2008-2010 by plasma clearance of iohexol (median 51 mL/min/1.73 m(2)). Bias, precision (interquartile range, IQR) and accuracy (percentage of estimates +/- 30% of mGFR; P-30) were compared. Results: Combined marker equations were unbiased and had higher precision and accuracy than single marker equations. Overall results of MEAN(LM-REV+CAPA)/MEAN(CKD-EPI)/CKD-EPICREA+CYSC were: median bias -2.2%/-0.5%/-1.6%, IQR 9.2/9.2/8.8 mL/min/1.73 m(2), and P-30 91.3%/91.0%/91.1%. The P-30 figures were about 7-14 -percentage points higher than the single marker equations. The combined equations also had a more stable performance across mGFR, age and BMI intervals, generally with P-30 >= 90% and never <80%. Combined equations reached P-30 of 95% when the difference between eGFR(CREA) and eGFR(CYSC) was <10% but decreased to 82% at a difference of >= 40%. Conclusions: Combining cystatin C and creatinine assays improves GFR estimations with P-30 >= 90% in adults. Reporting estimates of both single and combined marker equations in clinical settings makes it possible to assess the validity of the combined equation based on the agreement between the single marker equations.
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| 8. |
- Christensson, Anders, et al.
(author)
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Serum cystatin C advantageous compared with serum creatinine in the detection of mild but not severe diabetic nephropathy.
- 2004
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In: Journal of Internal Medicine. - : Wiley. - 1365-2796 .- 0954-6820. ; 256:6, s. 510-518
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Journal article (peer-reviewed)abstract
- OBJECTIVE: To determine whether serum cystatin C is more accurate than serum creatinine in the detection of diabetic nephropathy, also after adjustment for age.METHODS: Forty-one patients with type 1 and 82 patients with type 2 diabetes were evaluated with serum creatinine, serum cystatin C, and (51)Cr-EDTA clearance (reference method). Cystatin C was measured by a particle-enhanced turbidimetric method and creatinine by an enzymatic method. Statistical estimations were performed both without and with age adjustment created by z-scores for (51)Cr-EDTA clearance, creatinine, and cystatin C. The cut-off levels for glomerular filtration rate (GFR) ((51)Cr-EDTA clearance) were 60 and 80 mL min(-1) 1.73 m(-2), respectively, in absolute values and 80, 90 and 95% CIs, respectively, in age-adjusted values (z-scores).RESULTS: Estimations without age adjustment showed significantly (P = 0.0132) closer correlation for cystatin C (r = 0.817) versus (51)Cr-EDTA clearance as compared with creatinine (r = 0.678). However, when using age-adjusted values, the correlation for cystatin C and creatinine, respectively, versus (51)Cr-EDTA clearance did not differ. When comparing the diagnostic utilities for serum cystatin C versus serum creatinine in manifest renal impairment (GFR < 60 mL min(-1) 1.73 m(-2) or z-scores <-1.28 SD), there were no significant differences between the two markers whether age adjusted or not. However, for diagnosing mild nephropathy (GFR < 80 mL min(-1) 1.73 m(-2) or z-score -0.84 SD), serum cystatin C is significantly more useful.CONCLUSIONS: Serum cystatin C performed better compared with serum creatinine even when measured enzymatically, to detect mild diabetic nephropathy. However, serum creatinine was as efficient as serum cystatin C to detect advanced diabetic nephropathy.
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| 9. |
- Christensson, Anders, et al.
(author)
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Serum cystatin C is a more sensitive and more accurate marker of glomerular filtration rate than enzymatic measurements of creatinine in renal transplantation.
- 2003
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In: Nephron Physiology. - : S. Karger AG. - 1660-2137. ; 94:2, s. 19-27
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Journal article (peer-reviewed)abstract
- <i>Background/Aims:</i> Serum creatinine has several drawbacks as marker of glomerular filtration rate (GFR), and therefore serum cystatin C has been proposed as a more optimal GFR marker. Previous reports have suggested benefits of serum cystatin C measurements in patients with renal transplants. The purpose of the present study was to evaluate the diagnostic accuracy of cystatin C measurements compared with enzymatic creatinine measurements as serum markers of GFR (established from plasma clearance of iohexol) in a large cohort of stable renal transplant recipients and in the early postoperative phase. <i>Methods:</i> Renal transplant patients (n = 125) with stable graft function were evaluated from reciprocals of serum creatinine and cystatin C compared with iohexol clearance. Fourteen patients were examined immediately after the onset of renal function. Cystatin C was measured by a particle-enhanced turbidimetric method and creatinine by an enzymatic method. <i>Results:</i> In stable renal transplant recipients, serum cystatin C showed a significantly (p = 0.033) closer correlation (r = 0.89 or 79% co-variance) with iohexol clearance than did serum creatinine (r = 0.81 or 66% co-variance). Using the χ<sup>2</sup> test and a cut-off at 60 ml/min/1.73 m<sup>2</sup>, serum cystatin C levels demonstrated significantly higher sensitivity for early GFR impairment (p = 0.0045) compared with serum creatinine measurements. On the first day after transplantation, serum cystatin C fell more rapidly than serum creatinine. <i>Conclusion:</i> Serum cystatin C levels correlate significantly closer to accurate measurements of GFR and are significantly more sensitive to detect early GFR impairment than enzymatic measurements of creatinine in serum.
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| 10. |
- Christensson, Anders, et al.
(author)
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The shrunken pore syndrome is associated with declined right ventricular systolic function in a heart failure population – the HARVEST study
- 2016
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In: Scandinavian Journal of Clinical & Laboratory Investigation. - : Informa UK Limited. - 0036-5513 .- 1502-7686. ; 76:7, s. 568-574
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Journal article (peer-reviewed)abstract
- The close relationship between heart and kidney diseases was studied with respect to the ‘Shrunken pore syndrome’ that is characterized by a difference in renal filtration between cystatin C and creatinine. Patients were retrieved from the HeARt and brain failure inVESTigation trail (HARVEST) which is an ongoing study undertaken in individuals hospitalized for the diagnosis of heart failure. Ninety-five of 116 patients who underwent transthoracic echocardiograms (TTE) were eligible for this study. We used four different formulas for estimated glomerular filtration rate (eGFR); CKD-EPIcreatinine, CKD-EPIcystatin C, LMrev and CAPA. Presence of the syndrome was defined as eGFR cystatin C ≤ 60% of eGFR creatinine and absence of the syndrome as eGFR cystatin C >90% and <110% of eGFR creatinine. In a linear regression model, adjusted for age and sex, and the ‘Shrunken pore syndrome’ defined by the equation pair CAPA and LMrev and the equation pair CKD-EPIcystatin C and CKD-EPIcreatinine, echocardiographic parameters were studied. The ‘Shrunken pore syndrome’ showed statistically significant associations with measurements of right ventricular (RV) systolic function; (TAPSE and RV S’) (according to the equation pair CKD-EPIcystatin C and CKD-EPIcreatinine). In conclusion, heart failure patients with the ‘Shrunken pore syndrome’ are at increased risk of having RV systolic dysfunction whilst heart failure patients without ‘Shrunken pore syndrome’ seem protected. These findings may indicate common pathophysiological events in the kidneys and the heart explaining the observed increased risk of mortality in subjects with the ‘Shrunken pore syndrome’.
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| 11. |
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| 12. |
- Delanaye, Pierre, et al.
(author)
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CKD : A Call for an Age-Adapted Definition
- 2019
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In: Journal of the American Society of Nephrology. - 1046-6673. ; 30:10, s. 1785-1805
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Research review (peer-reviewed)abstract
- Current criteria for the diagnosis of CKD in adults include persistent signs of kidney damage, such as increased urine albumin-to-creatinine ratio or a GFR below the threshold of 60 ml/min per 1.73 m2 This threshold has important caveats because it does not separate kidney disease from kidney aging, and therefore does not hold for all ages. In an extensive review of the literature, we found that GFR declines with healthy aging without any overt signs of compensation (such as elevated single-nephron GFR) or kidney damage. Older living kidney donors, who are carefully selected based on good health, have a lower predonation GFR compared with younger donors. Furthermore, the results from the large meta-analyses conducted by the CKD Prognosis Consortium and from numerous other studies indicate that the GFR threshold above which the risk of mortality is increased is not consistent across all ages. Among younger persons, mortality is increased at GFR <75 ml/min per 1.73 m2, whereas in elderly people it is increased at levels <45 ml/min per 1.73 m2 Therefore, we suggest that amending the CKD definition to include age-specific thresholds for GFR. The implications of an updated definition are far reaching. Having fewer healthy elderly individuals diagnosed with CKD could help reduce inappropriate care and its associated adverse effects. Global prevalence estimates for CKD would be substantially reduced. Also, using an age-specific threshold for younger persons might lead to earlier identification of CKD onset for such individuals, at a point when progressive kidney damage may still be preventable.
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| 13. |
- Delanaye, Pierre, et al.
(author)
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Performance of creatinine-based equations to estimate glomerular filtration rate in White and Black populations in Europe, Brazil, and Africa
- 2022
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In: Nephrology, Dialysis and Transplantation. - : Oxford University Press. - 0931-0509 .- 1460-2385. ; 38:1, s. 106-118
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Journal article (peer-reviewed)abstract
- BACKGROUND: A new Chronic Kidney Disease Epidemiology equation without race variable has been recently proposed (CKD-EPIAS). This equation has neither been validated outside USA nor compared to the new European Kidney Function Consortium (EKFC) and Lund-Malmö Revised (LMREV) equations, developed in European cohorts.METHODS: Standardized creatinine and measured glomerular filtration rate (GFR) from the European EKFC cohorts (n = 13 856 including 6031 individuals in the external validation cohort), from France, (n = 4429, including 964 Black Europeans), from Brazil (n = 100), and from Africa (n = 508) were used to test the performances of the equations. A matched analysis between White Europeans and Black Africans or Black Europeans was performed.RESULTS: In White Europeans (n = 9496), both the EKFC and LMREV equations outperformed CKD-EPIAS (bias of -0.6 and -3.2, respectively versus 5.0 mL/min/1.73m², and accuracy within 30% of 86.9 and 87.4, respectively versus 80.9%). In Black Europeans and Black Africans, the best performance was observed with the EKFC equation using a specific Q-value ( = concentration of serum creatinine in healthy males and females). These results were confirmed in matched analyses, which showed that serum creatinine concentrations were different in White Europeans, Black Europeans, and Black Africans for the same measured GFR, age, sex and body mass index. Creatinine differences were more relevant in males.CONCLUSION: In a European and African cohort, the performances of CKD-EPIAS remain suboptimal. The EKFC equation, using usual or dedicated, population-specific Q-values presents the best performance in the whole age range in the European and African populations included in this study.
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| 14. |
- Delanaye, Pierre, et al.
(author)
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Performance of creatinine-based equations to estimate glomerular filtration rate with a methodology adapted to the context of drug dosage adjustment
- 2022
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In: British Journal of Clinical Pharmacology. - : Wiley-Blackwell Publishing Inc.. - 0306-5251 .- 1365-2125. ; 88:5, s. 2118-2127
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Journal article (peer-reviewed)abstract
- AIM: The Cockcroft-Gault (CG) creatinine-based equation is still used to estimate glomerular filtration rate (eGFR) for drug dosage adjustment. Incorrect eGFR may lead to hazardous over- or underdosing METHODS: In a cross-sectional analysis, CG was validated against measured GFR (mGFR) in 14,804 participants and compared with the Modification-of-Diet-in-Renal-Diseases (MDRD), Chronic-Kidney-Disease-Epidemiology (CKD-EPI), Lund-Malmö-Revised (LMR), and European-Kidney-Function-Consortium (EKFC) equations. Validation focused on bias, imprecision, and accuracy (percentage of estimates within ±30% of mGFR, P30), overall and stratified for mGFR, age, and body mass index at mGFR <60 mL/min, as well as classification in mGFR stages.RESULTS: The CG equation performed worse than the other equations, overall and in mGFR, age and BMI subgroups in terms of bias (systematic overestimation), imprecision and accuracy except for patients ≥65 years where bias and P30 were similar to MDRD and CKD-EPI, but worse than LMR and EKFC. In subjects with mGFR<60 mL/min and at BMI [18.5-25[kg/m2 , all equations performed similarly and for BMI<18.5kg/m2 CG and LMR had the best results though all equations had poor P30-accuracy. At BMI≥25kg/m2 the bias of the CG increased with increasing BMI (+17.2mL/min at BMI≥40kg/m2 ). The four more recent equations also classified mGFR stages better than CG.CONCLUSIONS: The CG equation showed poor ability to estimate GFR overall and in analyses stratified for GFR, age, and BMI. CG was inferior to correctly classify the patients in the mGFR staging compared to more recent creatinine-based equations.
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| 15. |
- Grubb, Anders, et al.
(author)
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Använd ekvationer utan »ras«- termer för att bestämma GFR
- 2022
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In: Läkartidningen. - 0023-7205. ; 119:21212
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Research review (peer-reviewed)abstract
- Glomerular filtration rate (GFR) is estimated by creatinine or cystatin C-based GFR-estimating equations. Those based upon creatinine, but not those based upon cystatin C, use ”race” terms due to that different populations differ in average muscular mass, influencing the creatinine, but not the cystatin C, level. “Race” is not a biological, but a sociological term, determined by self-assesment. New international studies therefore strongly recommend use of cystatin C-based GFR- estimating equations.
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| 16. |
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| 17. |
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| 18. |
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| 19. |
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| 20. |
- Grubb, Anders, et al.
(author)
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Reduction in glomerular pore size is not restricted to pregnant women. Evidence for a new syndrome: 'Shrunken pore syndrome'.
- 2015
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In: Scandinavian Journal of Clinical & Laboratory Investigation. - : Informa UK Limited. - 1502-7686 .- 0036-5513. ; 75:4, s. 333-340
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Journal article (peer-reviewed)abstract
- The plasma levels of cystatin C, β2-microglobulin, beta-trace protein, retinol binding protein (RBP) and creatinine were determined in plasma samples from 111 randomly selected patients with eGFRcystatin C ≤ 60% of eGFRcreatinine and from 55 control patients with 0.9eGFRcreatinine ≤ eGFRcystatin C ≤ 1.1eGFRcreatinine (eGFRcystatin C ≈ eGFRcreatinine). The concentration ratios of cystatin C/creatinine, β2-microglobulin/creatinine, beta-trace protein/creatinine and RBP/creatinine were significantly higher in patients with eGFRcystatin C ≤ 60% of eGFRcreatinine than in patients with eGFRcystatin C ≈ eGFRcreatinine. When the patients were divided into three groups with different estimated GFR intervals (≤ 40, 40-60 and ≥ 60 mL/min/1.73m(2)) the concentration ratios of cystatin C/creatinine, β2-microglobulin/creatinine, and beta-trace protein/creatinine were significantly higher in patients with eGFRcystatin C ≤ 60% of eGFRcreatinine than in patients with eGFRcystatin C ≈ eGFRcreatinine for all GFR intervals. Similar results were obtained when the population without pregnant women was studied as well as the subpopulations of men or of non-pregnant women. Populations of pre-eclamptic women and pregnant women in the third trimester display similar results. Since the production of these four proteins with sizes similar to that of cystatin C is not co-regulated, the most likely explanation for the simultaneous increase of their creatinine-ratios in patients with eGFRcystatin C ≤ 60% of eGFRcreatinine is that their elimination by glomerular filtration is decreased. We suggest that this is due to a reduction in pore diameter of the glomerular membrane and propose the designation 'Shrunken pore syndrome' for this pathophysiological state.
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| 21. |
- Grubb, Anders, et al.
(author)
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Simple Cystatin C-Based Prediction Equations for Glomerular Filtration Rate Compared with the Modification of Diet in Renal Disease Prediction Equation for Adults and the Schwartz and the Counahan-Barratt Prediction Equations for Children.
- 2005
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In: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 51:8, s. 1420-1431
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Journal article (peer-reviewed)abstract
- BACKGROUND: Serum creatinine is the most commonly used marker for estimation of glomerular filtration rate (GFR). To compensate for its drawbacks as a GFR marker, several prediction equations including several parameters are being used, with the Modification of Diet in Renal Disease (MDRD), Schwartz, and Counahan-Barratt equations being the ones most widely accepted for estimation of relative GFR in mL x min(-1) x (1.73 m(2))(-1). The present study analyzes whether these GFR prediction equations for adults and children might be replaced by simple prediction equations based on plasma concentrations of cystatin C.METHODS: Data from 536 patients (0.3-93 years), consecutively referred for determination of GFR by an invasive gold standard procedure, were used for the analysis. Calculations of bias (median percentage of error), correlation (adjusted R(2)), and percentage of estimates within 30% and 50% of measured GFR were used in the comparisons.RESULTS: A cystatin C-based prediction equation using only concentration in mg/L and a prepubertal factor: GFR [mL x min(-1) x (1.73 m(2))(-1)] = 84.69 x cystatin C (mg/L)(-1.680) x 1.384 (if a child <14 years) assessed GFR equally well or better than the simplified MDRD, the Schwartz, and the Counahan-Barratt prediction equations for the adult (> or =18 years) and juvenile groups of the investigated cohort. Age did not influence the cystatin C-based prediction equation for adults, whereas gender did, but with a factor close to unity (0.948 for females).CONCLUSION: A GFR prediction equation based solely on cystatin C (in mg/L) and a prepubertal factor might replace the simplified MDRD prediction equation for adults and the Schwartz and Counahan-Barratt prediction equations for children.
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| 22. |
- Grubb, R, et al.
(author)
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Assignment of allotypes G1m(a+) and G1m(a-) at the genomic level by polymerase chain reaction analysis
- 1990
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In: Experimental and Clinical Immunogenetics. - 0254-9670. ; 7:4, s. 205-212
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Journal article (peer-reviewed)abstract
- A method of assignment of the human immunoglobulin allotypes G1m(a+) and G1m(a-) without the use of serological reagents is described. It is based upon oligonucleotide-directed enzymatic amplification of genomic segments encoding CH3 of gamma chains, followed by dot-blot hybridization of radioactively labelled oligonucleotides to the amplified DNA. The method was used to classify the immunoglobulin allotypes of 11 persons, six G1m(a+) and five G1m(a-), and the resultant classification agreed completely with that of classical serological typing.
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| 23. |
- Hall, Anders, et al.
(author)
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Cystatin C based peptidyl diazomethanes as cysteine proteinase inhibitors: Influence of the peptidyl chain length
- 1992
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In: Journal of Enzyme Inhibition and Medicinal Chemistry. - : Informa UK Limited. - 1475-6374. ; 6:2, s. 113-123
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Journal article (peer-reviewed)abstract
- The peptidyl diazomethanes Cbz-Gly-CHN2, Boc-Val-Gly-CHN2, H-Leu-Val-Gly-CHN2, Cbz-Leu-Val-Gly-CHN2 and Cbz-Arg-Leu-Val-Gly-CHN2, with peptidyl portions modelled after the proposed cysteine proteinase interacting N-terminal segment of human cystatin C, were synthesized. Their efficiency as cysteine proteinase inhibitors was tested against papain, human cathepsin B and bovine cathepsin B. All, except Cbz-Gly-CHN2, were found to be irreversible inhibitors of the tested enzymes. Each addition of an amino acid residue to their peptidyl portions resulted in an increased inhibition rate of all three enzymes. These data suggest that the arginyl residue of the tetrapeptidyl diazomethane, and also the corresponding arginyl residue in native cystatin C, interact with a S4 substrate pocket subsite of both papain and cathepsin B. The most efficient inhibitor, Cbz-Arg-Leu-Val-Gly-CHN2, inhibited papain and cathepsin B with rate constants of the same order of magnitude as those for L-3-carboxy-trans-2.3-epoxypropionyl-leucylamido-(4-guanidino)butane (E-64). The high water-solubility of Cbz-Arg-Leu-Val-Gly-CHN2 allowing it to be dissolved to molar concentrations without use of non-physiological additives, makes it suitable for in vitro and in vivo cysteine proteinase inhibition studies.
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| 24. |
- Hall, Anders, et al.
(author)
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Importance of the evolutionarily conserved glycine residue in the N-terminal region of cystatin C (Gly-11) for cysteine endopeptidase inhibition
- 1993
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In: Biochemical Journal. - 0264-6021. ; 291:1, s. 123-129
-
Journal article (peer-reviewed)abstract
- Human cystatin C variants in which the evolutionarily conserved Gly-11 residue has been replaced by residues with positively charged (Arg), negatively charged (Glu), bulky hydrophobic (Trp), or small (Ser or Ala) side-chains have been produced by site-directed mutagenesis and expression in Escherichia coli. The five variants were isolated and structurally verified. Their inhibitory properties were compared with those of wild-type recombinant cystatin C by determination of the equilibrium constants for dissociation (Ki) of their complexes with the cysteine endopeptidases papain and human cathepsin B and with the cysteine exopeptidase dipeptidyl peptidase I. The Ser-11 and Ala-11 cystatin C variants displayed Ki values for the two endopeptidases that were approx. 20-fold higher than those of wild-type cystatin C, while the corresponding values for the Trp-11. Arg-11 and Glu-11 variants were increased by a factor of about 2000. In contrast, the Ki values for the interactions of all five variants with the exopeptidase differed from that of wild-type cystatin C by a factor of less than 10. Wild-type cystatin C and the Ser-11, Ala-11 and Glu-11 variants were incubated with neutrophil elastase, which in all cases resulted in the rapid hydrolysis of a single peptide bond, between amino acid residues 10 and 11. The Ki values for the interactions with papain of these three N-terminal-decapeptide-lacking cystatin C variants were 20-50 nM, just one order of magnitude higher than the value for N-terminally truncated wild-type cystatin C, which in turn was similar to the corresponding values for the full-length Glu-11, Arg-11 and Trp-11 variants. These data indicate that the crucial feature of the conserved Gly residue in position 11 of wild-type cystatin C is that this residue, devoid of a side-chain, will allow the N-terminal segment of cystatin C to adopt a conformation suitable for interaction with the substrate-binding pockets of cysteine endopeptidases, resulting in high-affinity binding and efficient inhibition. The functional properties of the remaining part of the proteinase contact area, which is built from more C-terminal inhibitor segments, are not significantly affected even when amino acids with bulky or charged side-chains replace the Gly-11 residue of the N-terminal segment.
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| 25. |
- Hall, Anders, et al.
(author)
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Structural basis for different inhibitory specificities of human cystatins C and D
- 1998
-
In: Biochemistry. - 0006-2960. ; 37:12, s. 4071-4079
-
Journal article (peer-reviewed)abstract
- Human cystatins C and D share almost identical primary structures of two out of the three segments proposed to be of importance for enzyme interactions but have markedly different profiles for inhibition of the target cysteine peptidases, cathepsins B, H, L, and S. To investigate if the N-terminal binding regions of the inhibitors are responsible for the different inhibition profiles, and thereby confer biological selectivity, two hybrid cystatins were produced in Escherichia coli expression systems. In one hybrid, the N-terminal segment of cystatin C was placed on the framework of cystatin D, and the second was engineered with the N-terminal segment of cystatin D on the cystatin C scaffold. Truncated cystatin C and D variants, devoid of their N-terminal segments, were obtained by incubation with glycyl endopeptidase and isolated, in a second approach to assess the importance of the N-terminal binding regions for cystatin function and specificity. The affinities of the four cystatin variants for cathepsins B, H, L, and S were measured. By comparison with corresponding results for wild-type cystatins C and D, it was concluded (1) that both the N-terminal and framework part of the molecules significantly contribute to the observed differences in inhibitory activities of cystatins C and D and (2) that the N-terminal segment of cystatin C increases the inhibitory activity of cystatin D against cathepsin S and cathepsin L but results in decreased activity against cathepsin H. These differences in specificity were explained by the residues interacting with the S2 subsite of peptidases (Val- and Ala-10 in cystatin C and D, respectively). Also, removal of the N-terminal segment results in total loss of enzyme affinity for cystatin D but not for cystatin C. Therefore, structural differences in the framework parts, as well as in the N-terminal segments, are critical for both inhibitory specificity and potency. Homology modeling was used to identify residues likely responsible for the generally reduced inhibitory potency of cystatin D.
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| 26. |
- Hall, Anders, et al.
(author)
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Structural basis for the biological specificity of cystatin C. Identification of leucine 9 in the N-terminal binding region as a selectivity-conferring residue in the inhibition of mammalian cysteine peptidases
- 1995
-
In: Journal of Biological Chemistry. - 1083-351X. ; 270:10, s. 5115-5121
-
Journal article (peer-reviewed)abstract
- The structural basis for the biological specificity of human cystatin C has been investigated. Cystatin C and other inhibitors belonging to family 2 of the cystatin superfamily interact reversibly with target peptidases, seemingly by independent affinity contributions from a wedge-shaped binding region built from two loop-forming inhibitor segments and a binding region corresponding to the N-terminal segment of the inhibitor. Human cystatin C variants with Gly substitutions for residues Arg-8, Leu-9, and/or Val-10 of the N-terminal binding region, and/or the evolutionarily conserved Trp-106 in the wedge-shaped binding region, were produced by site-directed mutagenesis and Escherichia coli expression. A total of 10 variants were isolated, structurally verified, and compared to wild-type cystatin C with respect to inhibition of the mammalian cysteine peptidases, cathepsins B, H, L, and S. Varying contributions from the N-terminal binding region and the wedge-shaped binding region to cystatin C affinity for the four target peptidases were observed. Interactions from the side chains of residues in the N-terminal binding region and Trp-106 are jointly responsible for the major part of cystatin C affinity for cathepsin L and are also of considerable importance for cathepsin B and H affinity. In contrast, for cathepsin S inhibition these interactions are of lesser significance, as reflected by a Ki value of 10(-8) M for the cystatin C variant devoid of Arg-8, Leu-9, Val-10, and Trp-106 side chains. The side chain of Val-10 is responsible for most of the affinity contribution from the N-terminal binding region, for all four enzymes. The contribution of the Arg-8 side chain is minor, but significant for cystatin C interaction with cathepsin B. The Leu-9 side chain confers selectivity to the inhibition of the target peptidases; it contributes to cathepsin B and L affinity by factors of 200 and 50, respectively, to cathepsin S binding by a factor of 5 only, and results in a 10-fold decreased affinity between cystatin C and cathepsin H.
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| 27. |
- Hansson, Lars-Olof, et al.
(author)
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Performance evaluation of a turbidimetric cystatin C assay on different high-throughput platforms
- 2010
-
In: Scandinavian Journal of Clinical & Laboratory Investigation. - : Informa UK Limited. - 1502-7686 .- 0036-5513. ; 70:5, s. 347-353
-
Journal article (peer-reviewed)abstract
- Objective. The goal with this study was to evaluate the analytical performance of a new cystatin C immunoassay (Tina-quant (R) a Cystatin C, Roche Diagnostics GmbH). The evaluation was carried out at four centers according to a standardized protocol. Material and methods. The Tina-quant (R) a Cystatin C is a latex particle-enhanced immunoturbidimetric assay. Roche cobas (R) 6000, MODULAR ANALYTICS SWA and COBAS INTEGRA (R) instruments were included in the study. Method comparison studies were carried out against two turbidimetric methods (Dako Cystatin C, Gentian Cystatin C), and one nephelometric method (Siemens N-Latex Cystatin C). Results. Linearity was proven throughout the measuring range from 0.4 to 8 mg/L. Within-run CVs ranged from 0.7-2.8%, and total CVs from 1.4-4.7 % (concentration range 0.6-3.9 mg/L). Comparable results were obtained with paired serum and Li-heparinate plasma samples. Good agreement was achieved in the comparisons between the Tina-quant (R) a Cystatin C assay and the other commercially available cystatin C assays, two different turbidimetric methods (slope range 0.88-1.04, intercept < 0.17 mg/L, r >= 0.993) and one nephelometric assay (slope range 0.90-1.05, intercept < 0.21 mg/L, r >= 0.986). Conclusions. The Tina-quant (R) a Cystatin C assay was shown to be precise and accurate with proven linearity over the measuring range. Good comparability was obtained with other commercially available assays for the determination of cystatin C. The Tina-quant (R) a Cystatin C assay is very well suited for clinical use on routine clinical chemistry analysers to detect renal dysfunction with a 24 h availability.
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| 28. |
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| 29. |
- Johansson, Anders, et al.
(author)
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Cisplatin pharmacokinetics and pharmacodynamics in patients with squamous-cell carcinoma of the head/neck or esophagus
- 1996
-
In: Cancer Chemotherapy and Pharmacology. - : Springer Science and Business Media LLC. - 0344-5704 .- 1432-0843. ; 39, s. 25-33
-
Journal article (peer-reviewed)abstract
- The pharmacokinetics of total platinum (Pt) in plasma and cisplatin (CDDP)-DNA adducts in different cell types were described in ten patients with squamous-cell carcinoma of the head/neck or esophagus after their first cycle of chemotherapy containing a CDDP dose of 100 mg/m2. Nephrotoxicity was studied in terms of urinary excretion of marker proteins (protein HC, IgG, and albumin). Pharmacodynamic relationships between pharmacokinetic parameters and toxicity were investigated. A population-based model with limited sampling was found feasible for producing pharmacokinetic information, in accordance with literature data. The kinetics of two normal cell types with different turnover (lymphocytes and buccal cells) appeared to have different kinetic profiles of CDDP-DNA adducts. Analysis of urinary excretion of marker proteins (protein HC, albumin, and IgG) showed that the nephrotoxicity was displayed first as tubular damage and later as impaired glomerular barrier function. There were indications that tubular nephrotoxicity may be predicted by pharmacokinetic parameters of plasma Pt. We found older patients to have a lower Pt clearance and more extensive early tubular damage. There was no correlation between CDDP-DNA adducts in normal cells and nephrotoxicity. Larger studies are warranted to define the pharmacokinetic window of CDDP. Limited sampling for analysis of CDDP pharmacokinetics may then be a possible avenue for individualizing the dose and, thus, improving the clinical use of the drug.
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| 30. |
- Jonsson, M, et al.
(author)
-
Plasmaproteiner, inflammation och amyloidos
- 2018. - 10
-
In: Laurells klinisk kemi i praktisk medicin.. - Lund : Studentlitteratur AB. - 9789144119748 ; , s. 87-130
-
Book chapter (peer-reviewed)
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| 31. |
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| 32. |
- Leion, Felicia, et al.
(author)
-
Estimating glomerular filtration rate (GFR) in children. The average between a cystatin C- and a creatinine-based equation improves estimation of GFR in both children and adults and enables diagnosing Shrunken Pore Syndrome.
- 2017
-
In: Scandinavian Journal of Clinical and Laboratory Investigation. - : Informa UK Limited. - 0036-5513 .- 1502-7686. ; 77:5, s. 338-344
-
Journal article (peer-reviewed)abstract
- Estimating glomerular filtration rate (GFR) in adults by using the average of values obtained by a cystatin C- (eGFRcystatin C) and a creatinine-based (eGFRcreatinine) equation shows at least the same diagnostic performance as GFR estimates obtained by equations using only one of these analytes or by complex equations using both analytes. Comparison of eGFRcystatin C and eGFRcreatinine plays a pivotal role in the diagnosis of Shrunken Pore Syndrome, where low eGFRcystatin C compared to eGFRcreatinine has been associated with higher mortality in adults. The present study was undertaken to elucidate if this concept can also be applied in children. Using iohexol and inulin clearance as gold standard in 702 children, we studied the diagnostic performance of 10 creatinine-based, 5 cystatin C-based and 3 combined cystatin C-creatinine eGFR equations and compared them to the result of the average of 9 pairs of a eGFRcystatin C and a eGFRcreatinine estimate. While creatinine-based GFR estimations are unsuitable in children unless calibrated in a pediatric or mixed pediatric-adult population, cystatin C-based estimations in general performed well in children. The average of a suitable creatinine-based and a cystatin C-based equation generally displayed a better diagnostic performance than estimates obtained by equations using only one of these analytes or by complex equations using both analytes. Comparing eGFRcystatin and eGFRcreatinine may help identify pediatric patients with Shrunken Pore Syndrome.
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| 33. |
- Lindström, Veronica, et al.
(author)
-
Different elimination patterns of beta-trace protein, beta(2)-microglobulin and cystatin C in haemodialysis, haemodiafiltration and haemofiltration.
- 2008
-
In: Scandinavian Journal of Clinical & Laboratory Investigation. - : Informa UK Limited. - 1502-7686 .- 0036-5513. ; 68, s. 685-691
-
Journal article (peer-reviewed)abstract
- Objective. Low molecular mass proteins (LMMP) are putative uraemic toxins, but their elimination is negligible in standard haemodialysis (HD). In this study, we used beta(2)-microglobulin, cystatin C and beta-trace protein, which differ in molecular mass and charge, to characterize the elimination patterns of three different dialysis modalities. Material and methods. Plasma samples were obtained at the start, 30 min after the start, at the end of the dialysis treatment and 30 min after termination of the dialysis session. Seventeen patients were treated with low-flux HD, 13 with post-dilution haemodiafiltration (HDF) and 8 with pre-dilution haemofiltration (HF). The changes in concentrations of the three LMMPs were monitored and expressed as percentages of the concentrations at the start of treatments. Results. Conventional HD with low-flux membranes showed a high elimination of small molecules (urea and creatinine), but did not reduce the levels of the three LMMPs studied. During HDF and HF, there was a significant decrease in the plasma levels of cystatin C (to 28 % and 44 %, respectively) (p<0.001) and of beta(2)-microglobulin (to 23 % and 33 %, respectively) (p<0.001). However, the level of beta-trace protein was significantly reduced (to 65 %) only after HDF. Conclusions . The three dialysis modalities showed significantly different elimination patterns for the LMMPs studied. Elimination of beta-trace protein was lower than those of cystatin C and beta(2)-microglobulin both in HDF and HF. beta-trace protein was only moderately eliminated by HDF and not at all by HF, and may be a useful marker in the evaluation of different convective therapies.
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| 34. |
- Nyman, Ulf, et al.
(author)
-
[GFR estimation in children - age-adjusted creatinine makes the adult Lund-Malmö equation applicable in children and facilitates automatic GFR reporting from the clinical laboratory]
- 2021
-
In: Läkartidningen. - : Läkartidningen Förlag AB. - 0023-7205 .- 1652-7518. ; 118
-
Journal article (peer-reviewed)abstract
- Age-adjustment of creatinine, i.e. recalculation of childhood levels of creatinine to corresponding levels at 18 years of age and applied in the adult revised Lund-Malmö GFR equation led to markedly improved accuracy in Swedish children (n=1 718) at measured GFR <75 mL/min/1.73 m2 (n=318) and preserved high accuracy at ≥75 mL/min/1.73 m2 (n=1 400). The adjusted LMR equation performed as well as dedicated paediatric equations based on height. The proposed adjustment strategy has four strengths: (i) the original coefficients of the adult GFR equation can be used, (ii) the same equation can be used across the entire lifespan without artificial changes in estimated GFR when switching from paediatric to adult care, (iii) the lack of height factor makes it easier to automatically report estimated GFR by the laboratories and (iv) age-adjusted creatinine values imply that well-established creatinine reference intervals for adults can also be used for children.
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| 35. |
- Nyman, Ulf, et al.
(author)
-
Så kan formel för vuxna skatta glomerulär filtration hos barn
- 2021
-
In: Lakartidningen. - 0023-7205. ; 118
-
Journal article (peer-reviewed)abstract
- Age-adjustment of creatinine, i.e. recalculation of childhood levels of creatinine to corresponding levels at 18 years of age and applied in the adult revised Lund-Malmö GFR equation led to markedly improved accuracy in Swedish children (n=1 718) at measured GFR <75 mL/min/1.73 m2 (n=318) and preserved high accuracy at ≥75 mL/min/1.73 m2 (n=1 400). The adjusted LMR equation performed as well as dedicated paediatric equations based on height. The proposed adjustment strategy has four strengths: (i) the original coefficients of the adult GFR equation can be used, (ii) the same equation can be used across the entire lifespan without artificial changes in estimated GFR when switching from paediatric to adult care, (iii) the lack of height factor makes it easier to automatically report estimated GFR by the laboratories and (iv) age-adjusted creatinine values imply that well-established creatinine reference intervals for adults can also be used for children.
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| 36. |
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| 37. |
- Nyman, Ulf, et al.
(author)
-
The revised Lund-Malmo GFR estimating equation outperforms MDRD and CKD-EPI across GFR, age and BMI intervals in a large Swedish population
- 2014
-
In: Clinical Chemistry and Laboratory Medicine. - : Walter de Gruyter GmbH. - 1434-6621 .- 1437-4331. ; 52:6, s. 815-824
-
Journal article (peer-reviewed)abstract
- Background: The performance of creatinine-based glomerular filtration rate (GFR) estimating equations may vary in subgroups defined by GFR, age and body mass index (BMI). This study compares the performance of the Modification of Diet in Renal Disease (MDRD) study and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations with the revised Lund-Malmo equation (LM Revised), a new equation that can be expected to handle changes in GFR across the life span more accurately. Methods: The study included 3495 examinations in 2847 adult Swedish patients referred for measurement of GFR (mGFR) 2008-2010 by plasma clearance of iohexol (median 52 mL/min/1.73 m(2)). Bias, precision [interquartile range (IQR)] and accuracy [percentage of estimates +/- 10% (P-10) and +/- 30% (P-30) of mGFR] were compared. Results: The overall results of LM Revised/MDRD/CKD-EPI were: median bias 2%/8%/11%, IQR 12/14/14 mL/min/1.73 m(2), P-10 40%/35%/35% and P-30 84%/75%/76%. LM Revised was the most stable equation in terms of bias, precision and accuracy across mGFR, age and BMI intervals irrespective of gender. MDRD and CKD-EPI overestimated mGFR in patients with decreased kidney function, young adults and elderly. All three equations overestimated mGFR and had low accuracy in patients with BMI <20 kg/m(2), most pronounced among men. Conclusions: In settings similar to the investigated cohort LM Revised should be preferred to MDRD and CKD-EPI due to its higher accuracy and more stable performance across GFR, age and BMI intervals.
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| 38. |
- Pottel, Hans, et al.
(author)
-
Cystatin C–Based Equation to Estimate GFR without the Inclusion of Race and Sex
- 2023
-
In: The New England journal of medicine. - : Massachusetts Medical Society. - 0028-4793 .- 1533-4406. ; 388:4, s. 333-343
-
Journal article (peer-reviewed)abstract
- BACKGROUNDThe accuracy of estimation of kidney function with the use of routine metabolic tests, such as measurement of the serum creatinine level, has been controversial. The European Kidney Function Consortium (EKFC) developed a creatinine-based equation (EKFC eGFRcr) to estimate the glomerular filtration rate (GFR) with a rescaled serum creatinine level (i.e., the serum creatinine level is divided by the median serum creatinine level among healthy persons to control for variation related to differences in age, sex, or race). Whether a cystatin C–based EKFC equation would increase the accuracy of estimated GFR is unknown.METHODSWe used data from patients in Sweden to estimate the rescaling factor for the cystatin C level in adults. We then replaced rescaled serum creatinine in the EKFC eGFRcr equation with rescaled cystatin C, and we validated the resulting EKFC eGFRcys equation in cohorts of White patients and Black patients in Europe, the United States, and Africa, according to measured GFR, levels of serum creatinine and cystatin C, age, and sex.RESULTSOn the basis of data from 227,643 patients in Sweden, the rescaling factor for cystatin C was estimated at 0.83 for men and women younger than 50 years of age and 0.83+0.005×(age–50) for those 50 years of age or older. The EKFC eGFRcys equation was unbiased, had accuracy that was similar to that of the EKFC eGFRcr equation in both White patients and Black patients (11,231 patients from Europe, 1093 from the United States, and 508 from Africa), and was more accurate than the Chronic Kidney Disease Epidemiology Collaboration eGFRcys equation recommended by Kidney Disease: Improving Global Outcomes. The arithmetic mean of EKFC eGFRcr and EKFC eGFRcys further improved the accuracy of estimated GFR over estimates from either biomarker equation alone.CONCLUSIONSThe EKFC eGFRcys equation had the same mathematical form as the EKFC eGFRcr equation, but it had a scaling factor for cystatin C that did not differ according to race or sex. In cohorts from Europe, the United States, and Africa, this equation improved the accuracy of GFR assessment over that of commonly used equations.
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| 39. |
- Pottel, Hans, et al.
(author)
-
Cystatin C–Based Equation to Estimate GFR without the Inclusion of Race and Sex
- 2023
-
In: New England Journal of Medicine. - : Massachusetts Medical Society. - 0028-4793 .- 1533-4406. ; 388:4, s. 333-343
-
Journal article (peer-reviewed)abstract
- BackgroundThe accuracy of estimation of kidney function with the use of routine metabolic tests, such as measurement of the serum creatinine level, has been controversial. The European Kidney Function Consortium (EKFC) developed a creatinine-based equation (EKFC eGFRcr) to estimate the glomerular filtration rate (GFR) with a rescaled serum creatinine level (i.e., the serum creatinine level is divided by the median serum creatinine level among healthy persons to control for variation related to differences in age, sex, or race). Whether a cystatin C–based EKFC equation would increase the accuracy of estimated GFR is unknown.MethodsWe used data from patients in Sweden to estimate the rescaling factor for the cystatin C level in adults. We then replaced rescaled serum creatinine in the EKFC eGFRcr equation with rescaled cystatin C, and we validated the resulting EKFC eGFRcys equation in cohorts of White patients and Black patients in Europe, the United States, and Africa, according to measured GFR, levels of serum creatinine and cystatin C, age, and sex.ResultsOn the basis of data from 227,643 patients in Sweden, the rescaling factor for cystatin C was estimated at 0.83 for men and women younger than 50 years of age and 0.83+0.005×(age–50) for those 50 years of age or older. The EKFC eGFRcys equation was unbiased, had accuracy that was similar to that of the EKFC eGFRcr equation in both White patients and Black patients (11,231 patients from Europe, 1093 from the United States, and 508 from Africa), and was more accurate than the Chronic Kidney Disease Epidemiology Collaboration eGFRcys equation recommended by Kidney Disease: Improving Global Outcomes. The arithmetic mean of EKFC eGFRcr and EKFC eGFRcys further improved the accuracy of estimated GFR over estimates from either biomarker equation alone.ConclusionsThe EKFC eGFRcys equation had the same mathematical form as the EKFC eGFRcr equation, but it had a scaling factor for cystatin C that did not differ according to race or sex. In cohorts from Europe, the United States, and Africa, this equation improved the accuracy of GFR assessment over that of commonly used equations. (Funded by the Swedish Research Council.)
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| 40. |
- Pottel, Hans, et al.
(author)
-
Development and Validation of a Modified Full Age Spectrum Creatinine-Based Equation to Estimate Glomerular Filtration Rate : A Cross-sectional Analysis of Pooled Data
- 2021
-
In: Annals of Internal Medicine. - : American College of Physicians. - 0003-4819 .- 1539-3704. ; 174:2, s. 183-191
-
Journal article (peer-reviewed)abstract
- BACKGROUND: The Chronic Kidney Disease in Children Study (CKiD) equation for children and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation for adults are recommended serum creatinine (SCr)-based calculations for estimating glomerular filtration rate (GFR). However, these equations, as well as their combination, have limitations, notably the problem of implausible changes in GFR during the transition from adolescence to adulthood and overestimation of GFR in young adults. The full age spectrum (FAS) equation addresses these issues but overestimates GFR when SCr levels are low.OBJECTIVE: To develop and validate a modified FAS SCr-based equation combining design features of the FAS and CKD-EPI equations.DESIGN: Cross-sectional analysis with separate pooled data sets for development and validation.SETTING: = 13) with measured GFR available.PATIENTS: 11 251 participants in 7 studies (development and internal validation data sets) and 8378 participants in 6 studies (external validation data set).MEASUREMENTS: Clearance of an exogenous marker (reference method), SCr level, age, sex, and height were used to develop a new equation to estimate GFR.RESULTS: ] in adults) across the FAS (2 to 90 years) and SCr range (40 to 490 µmol/L [0.45 to 5.54 mg/dL]) and with fewer estimation errors exceeding 30% (6.5% [CI, 3.8% to 9.1%] in children and 3.1% [CI, 2.5% to 3.6%] in adults) compared with the CKiD and CKD-EPI equations.LIMITATION: No Black patients were included.CONCLUSION: The new EKFC equation shows improved accuracy and precision compared with commonly used equations for estimating GFR from SCr levels.PRIMARY FUNDING SOURCE: Swedish Research Council (Vetenskapsrådet).
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| 41. |
- Pottel, Hans, et al.
(author)
-
Extending the cystatin C based EKFC-equation to children - validation results from Europe.
- 2023
-
In: Pediatric nephrology (Berlin, West). - 0931-041X .- 1432-198X.
-
Journal article (peer-reviewed)abstract
- BACKGROUND: A new cystatin C based European Kidney Function Consortium (EKFCCysC) equation was recently developed for adults, using the same mathematical form as the previously published full age spectrum creatinine based EKFC-equation (EKFCCrea). In the present study the cystatin C based EKFC-equation is extended to children, by defining the appropriate cystatin C rescaling factor QCysC.METHODS: Rescaling factor QCysC for cystatin C was defined as: a) 0.83 mg/L, exactly as it was defined for young adults in the adult equation, and b) a more complex QCysC-age relationship based on 4th degree cystatin C-age polynomials after evaluation of data from Uppsala, Stockholm and Canada and aggregated data from Germany. The EKFCCysC equation was then validated in an independent dataset in European children (n = 2,293) with measured GFR, creatinine, cystatin C, age, height and sex available.RESULTS: The EKFCCysC with the simple QCysC-value of 0.83 had a bias of -7.6 [95%CI -8.4;-6.5] mL/min/1.73 m2 and a P30-value of 85.8% [95%CI 84.4;87.3] equal to the EKFCCysC with the more complex 4th degree QCysC-value. The arithmetic mean of the EKFCCrea and EKFCCysC with the simple QCysC of 0.83 had a bias of -4.0 [95%CI -4.5;-3.1] mL/min/1.73 m2 and P30 of 90.4% [95%CI 89.2;91.6] similar to using the more complex 4th degree QCysC-polynomial.CONCLUSION: Using exactly the same QCysC of 0.83 mg/L, the adult EKFCCysC can easily be extended to children, with some bias but acceptable P30-values. The arithmetic mean of EKFCCrea and EKFCCysC results in bias closer to zero and P30 slightly over 90%. A higher resolution version of the Graphical abstract is available as Supplementary information.
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| 42. |
- Pottel, Hans, et al.
(author)
-
Standardization of serum creatinine is essential for accurate use of unbiased estimated GFR equations : evidence from three cohorts matched on renal function
- 2022
-
In: Clinical Kidney Journal. - : Oxford University Press. - 2048-8505 .- 2048-8513. ; 15:12, s. 2258-2265
-
Journal article (peer-reviewed)abstract
- Background: Differences in the performance of estimated glomerular filtration rate (eGFR) equations have been attributed to the mathematical form of the equations and to differences between patient demographics and measurement methods. We evaluated differences in serum creatinine (SCr) and eGFR in cohorts matched for age, sex, body mass index (BMI) and measured GFR (mGFR).Methods: White North Americans from Minnesota (n = 1093) and the Chronic Renal Insufficiency Cohort (CRIC) (n = 1548) and White subjects from the European Kidney Function Consortium (EKFC) cohort (n = 7727) were matched for demographic patient characteristics (sex, age +/- 3 years, BMI +/- 2.5 kg/m(2)) and renal function (mGFR +/- 3 ml/min/1.73 m(2)). SCr was measured with isotope dilution mass spectrometry (IDMS)-traceable assays in the Minnesota and EKFC cohorts and with non-standardized SCr assays recalculated to IDMS in the CRIC. The Minnesota cohort and CRIC shared a common method to measure GFR (renal clearance of iothalamate), while the EKFC cohort used a variety of exogenous markers and methods, all with recognized sufficient accuracy. We compared the SCr levels and eGFR predictions [for Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and EKFC equations] of patients fulfilling these matching criteria.Results: For 305 matched individuals, mean SCr (mg/dL) was not different between the Minnesota and EKFC cohorts (females 0.83 +/- 0.20 versus 0.86 +/- 0.23, males 1.06 +/- 0.23 versus 1.12 +/- 0.37; P > .05) but significantly different from the CRIC [females 1.13 +/- 0.23 (P < .0001), males 1.42 +/- 0.31 (P < .0001)]. The CKD-EPI equations performed better than the EKFC equation in the CRIC, while the opposite was true in the Minnesota and EKFC cohorts.Conclusion: Significant differences in SCr concentrations between the Minnesota and EKFC cohorts versus CRIC were observed in subjects with the same level of mGFR and equal demographic characteristics and can be explained by the difference in SCr calibration.Lay Summary: Standardization of serum creatinine (SCr) measurement is fundamental for estimating glomerular filtration rate (GFR). We used data with GFR measured by a reference method from three cohorts: Chronic Renal Insufficiency Cohort (CRIC, n = 1548), Minnesota cohort (n = 1093) and European Kidney Function Consortium cohort (EKFC; n = 7727). In the EKFC and Minnesota cohorts, SCr was measured by standardized methods, although SCr 'calibration' was more debatable in the CRIC. GFR was measured by the same method in the CRIC and Minnesota cohort. Then we matched 305 White subjects for sex, measured GFR (+/- 3 ml/min/1.73 m(2)), age (+/- 3 years) and body mass index (+/- 2.5 kg/m(2)). From these matched subjects we showed that the association between SCr and measured GFR was quite similar between subjects from the Minnesota and EKFC cohorts, but different between the CRIC and EKFC cohort and between the Minnesota cohort and CRIC. These differences lead to discrepancies in the analysis of the performance of different creatinine-based equations.
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| 43. |
- Sällman Almén, Markus, et al.
(author)
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Shrunken Pore Syndrome Is Associated With Increased Levels of Atherosclerosis-Promoting Proteins
- 2019
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In: Kidney International Reports. - : Elsevier BV. - 2468-0249. ; 4:1, s. 67-79
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Journal article (peer-reviewed)abstract
- Introduction: Shrunken pore syndrome (SPS), originally defined by cystatin C-based estimated glomerular filtration rate (eGFRcystatin C) being less than 60% of creatinine-based estimated glomerular filtration rate (eGFRcreatinine) in the absence of extrarenal influences on the plasma levels of cystatin C or creatinine, is associated with a high increase in mortality, even in the absence of reduced glomerular filtration rate (GFR). The objective of the present study was to determine whether the proteome of patients with SPS shows differences from that of patients with normal or reduced measured GFR (mGFR) without SPS.Methods: Four patient cohorts were included: 1 cohort with normal mGFR without SPS, 1 with normal mGFR with SPS, 1 with reduced mGFR without SPS, and 1 with reduced mGFR with SPS. The plasma levels of 177 selected proteins were analyzed.Results: Differences in the levels of 30 proteins were specific for SPS; 31 differences were specific for patients with both SPS and reduced mGFR; and 27 were specific for reduced mGFR. Eighteen of the differences specific for SPS concerned proteins described as promoting, or being associated with, atherosclerosis. Twelve of the differences specific for patients with both SPS and reduced mGFR and 10 of the differences specific for reduced mGFR also concerned proteins described as promoting, or being associated with, atherosclerosis. Almost all (82 of 88) of the concentration differences represented increased levels. For SPS, but not for reduced mGFR, a correlation between protein size and increase in level was observed, with smaller proteins being associated with higher levels.Conclusion: The high mortality in shrunken pore syndrome might be caused by the accumulation of atherosclerosis-promoting proteins in this condition.
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| 44. |
- Wahlin, Anders, et al.
(author)
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Effects of plasmapheresis on the plasma concentration of proteins used to monitor the disease process in multiple myeloma
- 1988
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In: Acta Medica Scandinavica. - : Wiley. - 0001-6101. ; 223:3, s. 263-267
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Journal article (peer-reviewed)abstract
- We studied the influence of plasmapheresis on the plasma concentrations of proteins (IgG, IgA, beta 2-microglobulin) used for estimation of tumour cell mass in patients with multiple myeloma. Simultaneously, the effects of plasmapheresis on plasma concentrations of proteins (CRP, alpha 1-antitrypsin, haptoglobin) used for the assessment of inflammatory processes were studied. Also, changes in the plasma concentration of protein HC, a recently described protein occurring both as a free protein and as an IgA complex, were studied. The influence of plasmapheresis varied for the different proteins. The plasma levels of IgG, IgA, CRP, alpha 1-antitrypsin, and haptoglobin decreased during plasmapheresis. The simultaneous reduction of the level of protein HC was smaller than that of IgG, IgA and haptoglobin. The plasma concentration of beta 2-microglobulin did not decrease during plasmapheresis. The recovery rates of the proteins were found to be approximately inversely related to their molecular weights.
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| 45. |
- Xhakollari, Liana, et al.
(author)
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Proteins linked to atherosclerosis and cell proliferation are associated with the shrunken pore syndrome in heart failure patients
- 2021
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In: Proteomics Clinical Applications. - : Wiley. - 1862-8354 .- 1862-8346. ; 15:4
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Journal article (peer-reviewed)abstract
- PURPOSE: The "Shrunken pore syndrome" (SPS) is characterized by a difference in renal filtration between cystatin C and creatinine, resulting in a low eGFRcystatinC /eGFRcreatinine -ratio. Studies have demonstrated a high risk for cardiovascular morbidity and mortality for patients with SPS. In this discovery study, we explored associations between SPS and proteins implicated in cardiovascular disease and inflammation in patients with heart failure.EXPERIMENTAL DESIGN: Plasma samples from 300 individuals in HARVEST-Malmö trial hospitalized for the diagnosis of heart failure (mean age 74.9±11.5 years; 30.0% female), were analyzed with a proximity extension assay consisting of 92 proteins. A Bonferroni-corrected p-value of 0.05/92 = 5.4 × 10-4 was considered significant in the initial age and sex-adjusted analyses. Presence of SPS was defined as eGFRcystatinC ≤60% of eGFRcreatinine .RESULTS: SPS presented with significant associations (p < 5.4 × 10-4 ) in age and sex-adjusted logistic regressions with elevated levels of six proteins; scavenger receptor cysteine rich type 1 protein M130, tumor necrosis factor receptor 1, tumor necrosis factor receptor 2, osteoprotegerin, interleukin-2 receptor subunit alpha, and tyrosine-protein kinase receptor UFO. All proteins remained associated (p < 0.05) with SPS after multivariate adjustments.CONCLUSIONS AND CLINICAL RELEVANCE: In heart failure patients, SPS was associated with proteins linked to atherosclerosis and cell proliferation. This article is protected by copyright. All rights reserved.
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| 46. |
- Xhakollari, Liana, et al.
(author)
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The Shrunken pore syndrome is associated with poor prognosis and lower quality of life in heart failure patients : the HARVEST-Malmö study
- 2021
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In: ESC Heart Failure. - : Wiley. - 2055-5822. ; 8:5, s. 3577-3586
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Journal article (peer-reviewed)abstract
- AIMS: This study aimed to investigate the association between the 'Shrunken pore syndrome' (SPS) and risk of death, 30 day rehospitalization, and health-related quality of life (QoL) in heart failure (HF) patients. SPS is characterized by a difference in renal filtration between cystatin C and creatinine, resulting in a low eGFRcystatin C /eGFRcreatinine ratio.METHODS AND RESULTS: A total of 373 patients hospitalized for HF [mean age 74.8 (±12.1) years; 118 (31.6%) women] were retrieved from the HeARt and brain failure inVESTigation trial (HARVEST-Malmö). Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formulas were used for estimation of glomerular filtration rate (eGFR). Presence of SPS was defined as eGFRcystatin C ≤ 60% of eGFRcreatinine . In Cox regression multivariate models, associations between SPS, risk of death (median follow-up time 1.8 years), and risk of 30 day rehospitalization were studied. Associations between SPS and impaired QoL were studied using multivariate logistic regressions. In multivariate models, SPS was associated with all-cause mortality [124 events; hazard ratio (HR) 1.99; 95% confidence interval (95% CI) 1.23-3.21; P = 0.005] and with 30 day rehospitalization (70 events; HR 1.82; CI 95% 1.04-3.18; P = 0.036). Analyses of QoL, based on a Kansas City Cardiomyopathy Questionnaire overall score < 50, revealed that SPS was associated with higher risk of low health-related QoL (odds ratios 2.15; CI 95% 1.03-4.49; P = 0.042).CONCLUSIONS: The results of this observational study show for the first time an association between SPS and poor prognosis in HF. Further studies are needed to confirm the results in HF cohorts and experimental settings to identify pathophysiological mechanisms.
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| 47. |
- Åkesson, Anna, et al.
(author)
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Shrunken pore syndrome and mortality : a cohort study of patients with measured GFR and known comorbidities
- 2020
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In: Scandinavian Journal of Clinical and Laboratory Investigation. - : Informa UK Limited. - 1502-7686 .- 0036-5513. ; 80:5, s. 412-422
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Journal article (peer-reviewed)abstract
- Shrunken pore syndrome (SPS) is defined by a cystatin C-based estimation of glomerular filtration rate (eGFRCYS) being less than 60% or 70% of a creatinine-based GFR estimation (eGFRCR) in the absence of extrarenal influences on cystatin C or creatinine concentrations. SPS has been associated with a substantial increase in mortality or morbidity in all investigated populations. However, in these studies, neither the diagnoses, nor causes of death were described, and only estimated GFR was available. The present study concerns 2781 individuals with measured GFR (mGFR), known diagnoses, and known causes of death during 5.6 years in median. Cox multivariate proportional hazards regression model was used to estimate hazard ratios (HR) for all-cause and cancer, cardiovascular, diabetes or chronic kidney disease (CKD) as cause-specific mortality among patients with SPS. At an eGFRCYS/eGFRCR-ratio <0.70, the adjusted SPS death risk in the total cohort (HR 3.0, 95% CI 2.4-3.7) was clearly higher than that for the other diagnosis groups. In a sub-cohort of 1300 persons with or without diagnosis, but with normal mGFR, the all-cause mortality of SPS was markedly increased (HR 4.1, 95% CI 2.6-6.5). In a sub-cohort of 567 persons with normal mGFR and no diagnosis, the all-cause mortality of SPS was even more increased (HR 7.3, 95% CI 2.3-23). The prevalence of SPS in the total cohort was 23% and in the sub-cohorts 17 and 12%, respectively. As SPS is associated with a high mortality, occurs in the absence of reduced mGFR and albuminuria, it expands the spectrum of kidney disorders.
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| 48. |
- Öberg, Carl M., et al.
(author)
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Potential relationship between eGFRcystatin C /eGFRcreatinine -ratio and glomerular basement membrane thickness in diabetic kidney disease
- 2021
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In: Physiological Reports. - : Wiley. - 2051-817X.
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Journal article (peer-reviewed)abstract
- Diabetic kidney disease (DKD) is a leading cause of end-stage renal disease and renal replacement therapy worldwide. A pathophysiological hallmark of DKD is glomeru- lar basal membrane (GBM) thickening, whereas this feature is absent in minimal change disease (MCD). According to fundamental transport physiological principles, a thicker GBM will impede the diffusion of middle-molecules such as cystatin C, potentially leading to a lower estimated GFR (eGFR) from cystatin C compared to that of creatinine. Here we test the hypothesis that thickening of the glomerular filter leads to an increased diffusion length, and lower clearance, of cystatin C. Twenty- nine patients with a kidney biopsy diagnosis of either DKD (n = 17) or MCD (n = 12) were retrospectively included in the study. GBM thickness was measured at 20 sepa- rate locations in the biopsy specimen and plasma levels of cystatin C and creatinine were retrieved from health records. A modified two-pore model was used to simulate the effects of a thicker GBM on glomerular water and solute transport. The mean age of the patients was 52 years, and 38% were women. The mean eGFRcystatin C/ eGFRcreatinine-ratio was 74% in DKD compared to 98% in MCD (p < 0.001). Average GBM thickness was strongly inversely correlated to the eGFRcystatin C/eGFRcreatinine- ratio (Pearson's r = −0.61, p < 0.01). Two-pore modeling predicted a eGFRcystatin C/ eGFRcreatinine-ratio of 78% in DKD. We provide clinical and theoretical evidence sug- gesting that thickening of the glomerular filter, increasing the diffusion length of cys- tatin C, lowers the eGFRcystatin C/eGFRcreatinine-ratio in DKD.
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| 49. |
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| 50. |
- Abrahamson, Magnus, et al.
(author)
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Efficient production of native, biologically active human cystatin C by Escherichia coli
- 1988
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In: FEBS Letters. - 1873-3468. ; 236:1, s. 14-18
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Journal article (peer-reviewed)abstract
- A cDNA encoding the mature human cysteine proteinase inhibitor cystatin C was fused to the coding sequence for the Escherichia coli outer membrane protein A signal peptide, and the recombinant gene was expressed in E. coli under the control of the λ PR promoter, an optimized Shine-Dalgarno sequence and the λ cI 857 repressor. When induced at 42°C, such cells expressed large amounts of recombinant cystatin C. The recombinant protein was isolated in high yield and characterized. All physicochemical properties investigated, including the positions of disulfide bonds, indicated that the E. coli derived cystatin C was identical to cystatin C isolated from human biological fluids, except that the proline residue in position three was not hydroxylated. The recombinant protein displayed full biological activity against papain, cathepsin B and dipeptidyl peptidase I.
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