| 1. |
- Almokhtar, Mokhtar, 1977-
(författare)
-
Expression and regulation of steroid metabolizing enzymes in cells of the nervous and skeletal systems : Special focus on vitamin D metabolism
- 2018
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Little is known about the mechanisms of vitamin D actions in the brain and bone. In this study, the metabolism of vitamin D and its regulation in various cell cultures of the nervous and skeletal systems were examined.Human osteosarcoma Saos-2 cells, human primary osteoblasts (hOB) and murine motor neuron-like NSC-34 cells were found to express mRNA for all enzymes required in vitamin D3 metabolism as well as the vitamin D receptor (VDR) that mediates vitamin D actions. Also, production of 24,25-dihydroxyvitamin D3 was found in these cells. Studies on vitamin D metabolism in NSC-34 cells and in primary neuron-enriched cells from rat cerebral cortex indicate formation of a previously unknown major metabolite formed from 25-hydroxyvitamin D3. Evaluation of the NSC-34 cells suggests that this cell line could be a novel model for studies of neuronal vitamin D metabolism and its regulation by endogenous and exogenous compounds.Treatment with glucocorticoids down regulated mRNA expression for the CYP24A1 gene in Saos-2 and hOB cells. Additionally, the glucocorticoid prednisolone showed suppression of CYP24A1-mediated metabolism and CYP24A1 promoter activity in Saos-2 cells. In NSC-34 cells, CYP24A1 mRNA levels were up-regulated by prednisolone, 1α,25-dihydroxyvitamin D3 and its synthetic analogues, EB1089 and tacalcitol. Formation of an endogenous glucocorticoid, 11-deoxycortisol, was observed in Saos-2 cells. Effects of glucocorticoids on the vitamin D system in bone cells may contribute to the adverse side effects in long-term treatment with glucocorticoids. Also, there may be a correlation between the administration of corticosteroids and adverse effects in the CNS.Expression and effects of vitamin D on steroidogenic enzymes were studied in primary neuron-enriched rat cortex cells, primary rat astrocytes and human neuroblastoma SH-SY5Y cells. These different cell cultures all expressed CYP17A1, whereas only astrocytes expressed 3β-hydroxysteroid dehydrogenase (3β-HSD). 1α,25-Dihydroxyvitamin D3 suppressed mRNA levels and enzyme activity of CYP17A1 in SH-SY5Y cells and astrocytes. 1α,25-Dihydroxyvitamin D3 suppressed enzyme activity and mRNA levels of 3β-HSD in astrocytes. The results suggest that vitamin D-mediated regulation of CYP17A1 and 3β-HSD may play a role in the nervous system.The results presented here contribute to our understanding of vitamin D metabolism and effects of glucocorticoids in the brain and bone.
|
|
| 2. |
- Bodin, Karl, et al.
(författare)
-
Metabolism of 4 beta -hydroxycholesterol in humans
- 2002
-
Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 277:35, s. 31534-31540
-
Tidskriftsartikel (refereegranskat)abstract
- One of the major oxysterols in the human circulation is 4 beta-hydroxycholesterol formed from cholesterol by the drug-metabolizing enzyme cytochrome P450 3A4. Deuterium-labeled 4 beta-hydroxycholesterol was injected into two healthy volunteers, and the apparent half-life was found to be 64 and 60 h, respectively. We have determined earlier the half-lives for 7 alpha-, 27-, and 24-hydroxycholesterol to be approximately 0.5, 0.75, and 14 h, respectively. Patients treated with certain antiepileptic drugs have up to 20-fold increased plasma concentrations of 4 beta-hydroxycholesterol. The apparent half-life of deuterium-labeled 4 beta-hydroxycholesterol in such a patient was found to be 52 h, suggesting that the high plasma concentration was because of increased synthesis rather than impaired clearance. 4 beta-Hydroxycholesterol was converted into acidic products at a much slower rate than 7 alpha-hydroxycholesterol in primary human hepatocytes, and 4 beta-hydroxycholesterol was 7 alpha-hydroxylated at a slower rate than cholesterol by recombinant human CYP7A1. CYP7B1 and CYP39A1 had no activity toward 4 beta-hydroxycholesterol. These results suggest that the high plasma concentration of 4 beta-hydroxycholesterol is because of its exceptionally slow elimination, probably in part because of the low rate of 7 alpha-hydroxylation of the steroid. The findings are discussed in relation to a potential role of 4 beta-hydroxycholesterol as a ligand for the nuclear receptor LXR.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Galos, Peter, et al.
(författare)
-
Case report : An unusual presentation of renal hypertension after damage control surgery
- 2021
-
Ingår i: International Journal of Surgery Case Reports. - : Elsevier. - 2210-2612. ; 82
-
Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION AND IMPORTANCE: Hypertensive crisis may be a life-threatening condition to any patient and represents an even more serious condition in trauma patients following severe hemorrhage. CASE PRESENTATION: We present a case were surgical drape packing induced hypertensive crisis in a trauma patient, recently resuscitated from abdominal hemorrhage. CLINICAL DISCUSSION: We argue that direct compression of the kidney by the surgical drapes induced hypersecretion of renin with a mechanism equal to Page kidney. The hypertensive crisis as well as the hyperreninemia was resolved after removing the surgical drapes, and the patient's condition returned to normal without any sequelae. CONCLUSION: We encourage considering this unusual but important complication when packing of the abdomen has been carried out, and strongly recommend ruling out renin-mediated hypertension as a cause of post-operative hypertension in such cases.
|
|
| 6. |
- Nastase Mannila, Maria, et al.
(författare)
-
Identification of a Functional Apolipoprotein E Promoter Polymorphism Regulating Plasma Apolipoprotein E Concentration
- 2013
-
Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - 1079-5642 .- 1524-4636. ; 33:5, s. 1063-1069
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE:There is compelling evidence that the plasma apolipoprotein E (APOE) concentration, in addition to the APOE ε2/ε3/ε4 genotype, influences plasma lipoprotein levels, but the functional genetic variants influencing the plasma APOE concentration have not been identified.APPROACH AND RESULTSGenome-wide association studies in 2 cohorts of healthy, middle-aged subjects identified the APOE locus as the only genetic locus showing robust associations with the plasma APOE concentration. Fine-mapping of the APOE locus confirmed that the rs7412 ε2-allele is the primary genetic variant responsible for the relationship with plasma APOE concentration. Further mapping of the APOE locus uncovered that rs769446 (-427T/C) in the APOE promoter is independently associated with the plasma APOE concentration. Expression studies in 199 human liver samples demonstrated that the rs769446 C-allele is associated with increased APOE mRNA levels (P=0.015). Transient transfection studies and electrophoretic mobility shift assays in human hepatoma HepG2 cells corroborated the role of rs769446 in transcriptional regulation of APOE. However, no relationships were found between rs769446 genotype and plasma lipoprotein levels in 2 cohorts (n=1648 and n=1039) of healthy middle-aged carriers of the APOE ε3/ε3 genotype.CONCLUSIONS:rs769446 is a functional polymorphism involved in the regulation of the plasma APOE concentration.
|
|
| 7. |
- Sandholm, Kerstin, et al.
(författare)
-
Evaluation of a Novel Immunoassay for Quantification of C1q for Clinical Diagnostic Use
- 2019
-
Ingår i: Frontiers in Immunology. - : Frontiers Media S.A.. - 1664-3224. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: C1q is a valuable biomarker of disease activity in systemic lupus erythematosus (SLE). The "gold standard" assay, rocket immunoelectrophoresis (RIE), is time-consuming, and thus a shift to soluble immune precipitation techniques such as nephelometry has occurred. However, quantification of C1q with these techniques has been questioned as a result of the antibody binding properties of C1q. In the present work, we have compared results using various techniques (RIE, nephelometry, and ELISA) and have developed and validated a new magnetic bead-based sandwich immunoassay (MBSI). Methods: C1q was quantified by nephelometry and the new sandwich immunoassay in 45 serum samples analyzed using RIE. C1q was also assessed in plasma using RIE and sandwich immunoassay in samples from SLE patients with nephritis (n = 69), SLE patients without nephritis (n = 310) as classified by BILAG score, and matched controls (n = 322). In addition, cerebrospinal fluid (CSF) samples from 31 patients, previously analyzed with ELISA, were also analyzed with the MBSI to test the behavior of this new assay in the lower detection range. Results: We found a strong correlation between the new MBSI, RIE, and ELISA, but not with nephelometry. The MBSI demonstrated lower levels of C1q in SLE patients than in matched controls (p < 0.0001), and patients with nephritis had lower levels than patients without nephritis (p < 0.01). Similarily, RIE showed significant differences between the patient groups (p < 0.0001). An association was also found between the levels of C1q and the SLE disease activity index (SLEDAI). Furthermore, there was good correlation between the values obtained by MBSI and ELISA, in both serum (r = 0.960) and CSF (r = 0.786), underscoring the ability of both techniques to measure low concentrations of C1q with high accuracy. Conclusion: The sandwich immunoassay correlated well with RIE, but soluble immune precipitation techniques, such as nephelometry, did not appear suitable alternatives, since C1q itself, and possibly anti-C1q antibodies, interfered with the measurements. The new sandwich immunoassay is therefore a good replacement for RIE in monitoring SLE disease activity.
|
|
| 8. |
- Tang, Wanjin, et al.
(författare)
-
Estrogen-mediated regulation of CYP7B1 : a possible role for controlling DHEA levels in human tissues
- 2006
-
Ingår i: Journal of Steroid Biochemistry and Molecular Biology. - : Elsevier BV. - 0960-0760 .- 1879-1220. ; 100:1-3, s. 42-51
-
Tidskriftsartikel (refereegranskat)abstract
- The current study examines regulation of CYP7B1, a DHEA 7alpha-hydroxylase, by sex hormones. Transfection with estrogen receptor alpha and treatment with 17beta-estradiol in human embryonic kidney 293 cells significantly increased CYP7B1 catalytic activity and mRNA, and stimulated a human CYP7B1 reporter gene. Transfection with estrogen receptor beta showed similar but less significant effects. In the absence of receptors, 17beta-estradiol suppressed CYP7B1 activity, suggesting that estrogenic effects may be different in cells not expressing receptors. Quantitation of CYP7B1 mRNA in adult and fetal human tissues showed markedly higher CYP7B1 mRNA levels in fetal tissues compared with the corresponding adult ones, except in the liver. This indicates a tissue-specific, developmental regulation of CYP7B1 and suggests an important function for this enzyme in fetal life. DHEA secreted by fetal adrenals is an essential precursor for placental estrogen formation. Since CYP7B1 diverts DHEA from the sex hormone biosynthetic pathway, estrogen receptor-mediated up-regulation of CYP7B1 should lead to less DHEA available for sex hormone synthesis and may help to maintain normal levels of estrogens and androgens in human tissues, especially during fetal development. Regulation by estrogens may also be of importance in other processes where CYP7B1 is involved, including cholesterol homeostasis, cellular proliferation, and CNS function.
|
|
| 9. |
- Zenlander, Robin, et al.
(författare)
-
A wide scan of plasma proteins demonstrates thioredoxin reductase 1 as a potential new diagnostic biomarker for hepatocellular carcinoma
- 2023
-
Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 58:9, s. 998-1008
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Patients with liver cirrhosis are recommended ultrasonography screening for early detection of hepatocellular carcinoma to increase the chances of curative treatment. However, ultrasonography alone lacks in sensitivity. Adding plasma biomarkers may increase the detection rate. We performed a broad exploratory analysis to find new plasma proteins with potential applicability for HCC screening in patients with cirrhosis. Methods: In a protein discovery cohort of 172 patients with cirrhosis or HCC, we screened for 481 proteins with suspension bead array or proximity extension assay. From these, 24 proteins were selected for further analysis in a protein verification cohort (n = 160), using ELISA, Luminex or an electrochemiluminescence platform. A cut-off model and a stepwise logistic regression model were used to find combinations of proteins with the best discriminatory performance between HCC and cirrhosis. Results: Stepwise logistic regression revealed alpha-fetoprotein (AFP), decarboxy-prothrombin (DCP), thioredoxin reductase 1 (TXNRD1), and fibroblast growth factor 21 (FGF21) as the proteins with the best discriminatory performance between HCC and cirrhosis. Adding TXNRD1 to DCP and AFP increased the AUC from 0.844 to 0.878, and combining AFP, DCP and TXNRD1 with age and sex resulted in an AUC of 0.920. FGF21, however, did not further increase the performance when including age and sex. Conclusion: In the present study, TXNRD1 improves the sensitivity and specificity of AFP and DCP as HCC screening tools in patients with cirrhosis. We suggest that TXNRD1 should be validated in prospective settings as a new complementary HCC biomarker together with AFP and DCP.
|
|
