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1.
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2.
  • Buendia, Ruben, 1982, et al. (författare)
  • Estimation of body fluids with bioimpedance spectroscopy: state of the art methods and proposal of novel methods
  • 2015
  • Ingår i: Physiological Measurement. - : Institute of Physics Publishing (IOPP). - 0967-3334 .- 1361-6579. ; 36:10
  • Tidskriftsartikel (refereegranskat)abstract
    • Determination of body fluids is a useful common practice in determination of disease mechanisms and treatments. Bioimpedance spectroscopy (BIS) methods are non-invasive, inexpensive and rapid alternatives to reference methods such as tracer dilution. However, they are indirect and their robustness and validity are unclear. In this article, state of the art methods are reviewed, their drawbacks identified and new methods are proposed. All methods were tested on a clinical database of patients receiving growth hormone replacement therapy. Results indicated that most BIS methods are similarly accurate (e.g. < 0.5 +/- 3.0% mean percentage difference for total body water) for estimation of body fluids. A new model for calculation is proposed that performs equally well for all fluid compartments (total body water, extra-and intracellular water). It is suggested that the main source of error in extracellular water estimation is due to anisotropy, in total body water estimation to the uncertainty associated with intracellular resistivity and in determination of intracellular water a combination of both.
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3.
  • Buendia, R, et al. (författare)
  • Robustness study of the different immittance spectra and frequency ranges in bioimpedance spectroscopy analysis for assessment of total body composition.
  • 2014
  • Ingår i: Physiological measurement. - : Institute of Physics Publishing Ltd.. - 1361-6579 .- 0967-3334. ; 35:7, s. 1373-95
  • Tidskriftsartikel (refereegranskat)abstract
    • The estimation of body fluids is a useful and common practice for assessment of disease status and therapy outcomes. Electrical bioimpedance spectroscopy (EBIS) methods are noninvasive, inexpensive and efficient alternatives for determination of body fluids. One of the main source of errors in EBIS measurements in the estimation of body fluids is capacitive coupling. In this paper an analysis of capacitive coupling in EBIS measurements was performed and the robustness of the different immittance spectra against it tested. On simulations the conductance (G) spectrum presented the smallest overall error, among all immittance spectra, in the estimation of the impedance parameters used to estimate body fluids. Afterwards the frequency range of 10-500 kHz showed to be the most robust band of the G spectrum. The accuracy of body fluid estimations from the resulting parameters that utilized G spectrum and parameters provided by the measuring device were tested on EBIS clinical measurements from growth hormone replacement therapy patients against estimations performed with dilution methods. Regarding extracellular fluid, the correlation between each EBIS method and dilution was 0.93 with limits of agreement of 1.06 ± 2.95 l for the device, 1.10 ± 2.94 l for G [10-500 kHz] and 1.04 ± 2.94 l for G [5-1000 kHz]. Regarding intracellular fluid, the correlation between dilution and the device was 0.91, same as for G [10-500 kHz] and 0.92 for G [5-1000 kHz]. Limits of agreement were 0.12 ± 4.46 l for the device, 0.09 ± 4.45 for G [10-500 kHz] and 0.04 ± 4.58 for G [5-1000 kHz]. Such close results between the EBIS methods validate the proposed approach of using G spectrum for initial Cole characterization and posterior clinical estimation of body fluids status.
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4.
  • Burman, P., et al. (författare)
  • Deaths Among Adult Patients With Hypopituitarism: Hypocortisolism During Acute Stress, and De Novo Malignant Brain Tumors Contribute to an Increased Mortality
  • 2013
  • Ingår i: Journal of Clinical Endocrinology & Metabolism. - : Endocrine Society. - 0021-972X .- 1945-7197. ; 98:4, s. 1466-1475
  • Tidskriftsartikel (refereegranskat)abstract
    • Context: Patients with hypopituitarism have an increased standardized mortality rate. The basis for Objective: To investigate in detail the cause of death in a large cohort of patients with hypopituitarism Design and Methods: All-cause and cause-specific mortality in 1286 Swedish patients with Main Outcome Measures: Standardized mortality ratios (SMR) were calculated, with stratification for Results: An excess mortality was found, 120 deaths vs 84.3 expected, SMR 1.42 (95% confidence Conclusion: Two important causes of excess mortality were identified: first, adrenal crisis in response
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5.
  • Holmer, Helene, et al. (författare)
  • Fracture incidence in GH-deficient patients on complete hormone replacement including GH
  • 2007
  • Ingår i: Journal of Bone and Mineral Research. - : AMBMR. - 1523-4681 .- 0884-0431. ; 22:12, s. 1842-1850
  • Tidskriftsartikel (refereegranskat)abstract
    • Fracture risk in GHD patients is not definitely established. Studying fracture incidence in 832 patients on GH therapy and 2581 matched population controls, we recorded a doubled fracture risk in CO GHD women, but a significantly lower fracture risk in AO GHD men. Introduction: The objective of this study was to evaluate fracture incidence in patients with confirmed growth hormone deficiency (GHD) on replacement therapy (including growth hormone [GH]) compared with population controls, while also taking potential Confounders and effect modifiers into account. Materials and Methods: Eight hundred thirty-two patients with GHD and 2581 matched population controls answered a questionnaire about fractures and other background information. Incidence rate ratio (IRR) and 95% CI for first fracture were estimated. The median time on GH therapy for childhood onset (CO) GHD men and women was 15 and 12 yr, respectively, and 6 and 5 yr for adult onset (AO) GHD men and women, respectively. Results: A more than doubled risk (IRR, 2.29; 95 % CI 1.23-4.28) for nonosteoporotic fractures was recorded in women with CO GHD, whereas no risk increase was observed among CO GHD men (IRR, 0.61) and AO GHD women (IRR, 1.08). A significantly decreased incidence of fractures (IRR, 0.54; 95% C1, 0.34-0.86) was recorded in AO GHD men. Conclusions: Increased fracture risk in CO GHD women can most likely be explained by interaction between oral estrogen and the GH-IGF-I axis. The adequate substitution rate of testosterone (90%) and GH (94%) may have resulted in significantly lower fracture risk in AO GHD men.
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6.
  • Holmer, Helene, et al. (författare)
  • Nonfatal stroke, cardiac disease, and diabetes mellitus in hypopituitary patients on hormone replacement including growth hormone
  • 2007
  • Ingår i: Journal of Clinical Endocrinology and Metabolism. - : Oxford University Press. - 1945-7197 .- 0021-972X. ; 92:9, s. 3560-3567
  • Tidskriftsartikel (refereegranskat)abstract
    • Context: The impact of long-term GH replacement on cerebrovascular and cardiovascular diseases and diabetes mellitus in hypopituitary patients is unknown. Objective: The incidence of nonfatal stroke and cardiac events, and prevalence of type 2 diabetes mellitus ( T2D) and cardioprotective medication were compared between cohorts of GH-deficient (GHD) patients and population controls. Design and Participants: The incidence of nonfatal stroke and cardiac events was estimated retrospectively from questionnaires in 750 GHD patients and 2314 matched population controls. A prevalence of T2D and cardioprotective medication was recorded at the distribution of questionnaires. Time since first pituitary deficiency to start of GH therapy was 4 and 2 yr, and time on GH therapy was 6 yr for GHD women and men, respectively. Results: Lifelong incidence of nonfatal stroke was tripled in GHD women and doubled in GHD men, but a decline was seen in both genders during periods after first pituitary hormone deficiency and GHD, during which most patients had GH therapy. The lifelong incidence of nonfatal cardiac events declined in GHD men during first pituitary hormone deficiency and GHD periods. GHD women had a higher prevalence of T2D and lipid-lowering medication, whereas GHD men had a higher prevalence of antihypertensive medication. Conclusions: The declined risks of nonfatal stroke in both genders and of nonfatal cardiac events in GHD men during periods on GH replacement may be caused by prescription of cardioprotective drugs and 6-yr GH replacement. GHD women had an increased prevalence of T2D, partly attributed to higher body mass index and lower physical activity.
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7.
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8.
  • Seoane, F, et al. (författare)
  • Slightly superior performance of bioimpedance spectroscopy over single frequency regression equations for assessment of total body water.
  • 2015
  • Ingår i: Engineering in Medicine and Biology Society (EMBC), 2015 37th Annual International Conference of the IEEE. 25-29 Aug. 2015, Milan, Italy.. - : IEEE. - 1094-687X .- 1558-4615. - 9781424492718 - 9781424492701 ; 2015, s. 3707-10
  • Konferensbidrag (refereegranskat)abstract
    • Electrical bioimpedance has been used for several decades to assess body fluid distribution and body composition by using single frequency and bioimpedance spectroscopic (BIS) techniques. It remains uncertain whether BIS methods have better performance compare to single frequency regression equations. In this work the performance of two BIS methods and four different 50 kHz single frequency prediction equations was studied in a data set of wrist-to-ankle tetrapolar BIS measurements (5-1000 kHz) together with reference values of total body water obtained by tritium dilution in 92 patients. Data were compared using regression techniques and Bland-Altman plots. The results of this study showed that all methods produced similarly high correlation and concordance coefficients, indicating good accuracy as a method. Limits of agreement analysis indicated that the population level performance of Sun's prediction equations was very similar to the performance of both BIS methods. However, BIS methods in practice have slightly better predictive performance than the single-frequency equations as judged by higher correlation and the limits of agreement from the Bland-Altman analysis. In any case, the authors believe that an accurate evaluation of performance of the methods cannot be done as long as the evaluation is done using Bland-Altman analysis, the commonly accepted technique for this kind of performance comparisons.
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9.
  • Bengtsson, D., et al. (författare)
  • Long-Term Outcome and MGMT as a Predictive Marker in 24 Patients With Atypical Pituitary Adenomas and Pituitary Carcinomas Given Treatment With Temozolomide
  • 2015
  • Ingår i: Journal of Clinical Endocrinology & Metabolism. - : Oxford University Press. - 0021-972X .- 1945-7197. ; 100:4, s. 1689-1698
  • Tidskriftsartikel (refereegranskat)abstract
    • Context/Objective: Locally aggressive pituitary tumors (LAPT) and pituitary carcinomas respond poorly to conventional therapy and cytotoxic drugs. Temozolomide (TMZ) is an oral alkylating drug with good tolerability, approved for treatment of malignant gliomas. The experience of its use in pituitary tumors is limited. Design and Setting: We report on 24 patients with aggressive pituitary tumors (16 LAPTs, 8 carcinomas) treated with TMZ for a median of 6 months (range 1-23). Follow-up ranged from 4 to 91 months with a median of 32.5 months. 19/24 tumors were hormone secreting (PRL 9, ACTH 4, GH 4, GH/PRL 2). Ki-67 was 2-50% in LAPTs, and 5-80% in carcinomas. Main Outcome: Response to TMZ and the association with tumor expression of O6-methylguanine DNA methyltransferase (MGMT), MLH1, MSH2, and MSH6, examined by immunohistochemistry. Results: Complete tumor regression occurred in two carcinomas and persisted at follow-up after 48 and 91 months, respectively. Partial regress of tumor mass ranging from 35% to 80% occurred in 5 LAPTs and 2 carcinomas. Another patient with LAPT had a 71% decrease in prolactin levels without change in tumor volume. Three LAPTs could not be evaluated. Median MGMT staining was 9% (5-20%) in responders vs 93% (50-100%) in nonresponders. Loss of MSH2 and MSH 6 was observed in a single patient who had a rapid development of resistance to TMZ. Conclusions: This study shows that TMZ is a valuable treatment option for patients with uncontrolled pituitary tumors. The data suggest that tumoral MGMT staining below 50% is associated with a high likelihood of treatment response.
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10.
  • Bridel, Claire, et al. (författare)
  • Diagnostic Value of Cerebrospinal Fluid Neurofilament Light Protein in Neurology: A Systematic Review and Meta-analysis.
  • 2019
  • Ingår i: JAMA neurology. - : American Medical Association. - 2168-6157 .- 2168-6149. ; 76:9, s. 1035-1048
  • Tidskriftsartikel (refereegranskat)abstract
    • Neurofilament light protein (NfL) is elevated in cerebrospinal fluid (CSF) of a number of neurological conditions compared with healthy controls (HC) and is a candidate biomarker for neuroaxonal damage. The influence of age and sex is largely unknown, and levels across neurological disorders have not been compared systematically to date.To assess the associations of age, sex, and diagnosis with NfL in CSF (cNfL) and to evaluate its potential in discriminating clinically similar conditions.PubMed was searched for studies published between January 1, 2006, and January 1, 2016, reporting cNfL levels (using the search terms neurofilament light and cerebrospinal fluid) in neurological or psychiatric conditions and/or in HC.Studies reporting NfL levels measured in lumbar CSF using a commercially available immunoassay, as well as age and sex.Individual-level data were requested from study authors. Generalized linear mixed-effects models were used to estimate the fixed effects of age, sex, and diagnosis on log-transformed NfL levels, with cohort of origin modeled as a random intercept.The cNfL levels adjusted for age and sex across diagnoses.Data were collected for 10 059 individuals (mean [SD] age, 59.7 [18.8] years; 54.1% female). Thirty-five diagnoses were identified, including inflammatory diseases of the central nervous system (n = 2795), dementias and predementia stages (n = 4284), parkinsonian disorders (n = 984), and HC (n = 1332). The cNfL was elevated compared with HC in a majority of neurological conditions studied. Highest levels were observed in cognitively impaired HIV-positive individuals (iHIV), amyotrophic lateral sclerosis, frontotemporal dementia (FTD), and Huntington disease. In 33.3% of diagnoses, including HC, multiple sclerosis, Alzheimer disease (AD), and Parkinson disease (PD), cNfL was higher in men than women. The cNfL increased with age in HC and a majority of neurological conditions, although the association was strongest in HC. The cNfL overlapped in most clinically similar diagnoses except for FTD and iHIV, which segregated from other dementias, and PD, which segregated from atypical parkinsonian syndromes.These data support the use of cNfL as a biomarker of neuroaxonal damage and indicate that age-specific and sex-specific (and in some cases disease-specific) reference values may be needed. The cNfL has potential to assist the differentiation of FTD from AD and PD from atypical parkinsonian syndromes.
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