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Henze A, Frey SK, Raila J, Tepel M, Scholze A, Pfeiffer AFH, Weickert MO, Spranger J, Schweigert FJ. Evidence that kidney function but not type 2 diabetes determines retinol-binding protein 4 serum levels. Diabetes 2008; 57:3323-6. [PMID: 18796616 PMCID: PMC2584139 DOI: 10.2337/db08-0866] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE It has been suggested that retinol-binding protein 4 (RBP4) links adiposity, insulin resistance, and type 2 diabetes. However, circulating RBP4 levels are also affected by kidney function. Therefore, the aim of this study was to test whether RBP4 serum levels are primarily associated with kidney function or type 2 diabetes. RESEARCH DESIGN AND METHODS RBP4 serum concentration was determined by enzyme-linked immunosorbent assay in 126 nondiabetic and 104 type 2 diabetic subjects. The study population was divided according to estimated glomerular filtration rate (eGFR) into the following groups: eGFR >90 ml/min per 1.73 m(2) (n = 53), 60-90 ml/min per 1.73 m(2) (n = 90), 30-60 ml/min per 1.73 m(2) (n = 38), and <30 ml/min per 1.73 m(2) (n = 49). Each group was subdivided into nondiabetic and type 2 diabetic subjects. RESULTS RBP4 serum concentration was elevated (2.65 vs. 2.01 micromol/l; P < 0.001) and eGFR was reduced (56 vs. 74 ml/min per 1.73 m(2); P < 0.001) in type 2 diabetic vs. nondiabetic subjects, respectively. By stratifying for eGFR, no more differences in RBP4 serum concentration were detectable between type 2 diabetic and nondiabetic subjects. A linear regression analysis revealed an influence of eGFR (r = -0.477; P < 0.001) but not A1C (r = 0.093; P = 0.185) on RBP4 serum concentration. CONCLUSIONS Existing human data showing elevated RBP4 levels in type 2 diabetic patients may be the result of moderate renal insufficiency rather than support for the suggestion that RBP4 links obesity to type 2 diabetes.
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102
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Liu D, Yang D, He H, Chen X, Cao T, Feng X, Ma L, Luo Z, Wang L, Yan Z, Zhu Z, Tepel M. Increased transient receptor potential canonical type 3 channels in vasculature from hypertensive rats. Hypertension 2008; 53:70-6. [PMID: 19029480 DOI: 10.1161/hypertensionaha.108.116947] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We tested the hypothesis that transient receptor potential canonical type 3 (TRPC3) channels are increased in vascular smooth muscle cells and aortic tissue from spontaneously hypertensive rats (SHR) compared with normotensive Wistar Kyoto rats. Expression of TRPC3 was analyzed by immunohistochemistry and Western blotting. TRPC3 gene knockdown was performed by specific small interfering RNA and TRPC3 overexpression using the pAdEasy-1 system. Cytosolic calcium was measured using fluorescence spectrophotometry and vasoconstriction of aortic rings using a force transducer. In SHR, the expression of TRPC3 channel protein was significantly higher in aortic rings (1.48+/-0.05 versus 1.00+/-0.06; each n=6; P<0.01) and vascular smooth muscle cells (1.28+/-0.08 versus 1.00+/-0.03; each n=6; P<0.05) compared with Wistar Kyoto rats. Knockdown of TRPC3 gene expression by specific small interfering RNA significantly reduced the angiotensin II-induced calcium influx by 30+/-3% (n=6; P<0.01), whereas TRPC3 overexpression significantly increased it by 55+/-3% (n=6; P<0.01). The angiotensin II-induced calcium increase was significantly enhanced in vascular smooth muscle cells from SHR compared with Wistar Kyoto rats, even in the presence of the calcium channel blocker amlodipine. Angiotensin II significantly elevated the TRPC3 channel protein expression in vascular smooth muscle cells from SHR from 1.28+/-0.08 to 1.61+/-0.08 (each n=6; P<0.01). Angiotensin II-induced TRPC3 expression was prevented by telmisartan. Administration of telmisartan to SHR for 4 weeks significantly reduced blood pressure, angiotensin II-induced vasoconstriction, and TRPC3 channel protein expression in aortic tissue. TRPC3 expression was not significantly reduced after reduction of blood pressure in SHR using amlodipine. In conclusion, we give experimental evidence that increased TRPC3 channel protein expression in the vasculature is important for elevated blood pressure.
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Liu D, Zhu Z, Tepel M. The Role of Transient Receptor Potential Channels in Metabolic Syndrome. Hypertens Res 2008; 31:1989-95. [DOI: 10.1291/hypres.31.1989] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Compton F, Wittrock M, Schaefer JH, Zidek W, Tepel M, Scholze A. Noninvasive cardiac output determination using applanation tonometry-derived radial artery pulse contour analysis in critically ill patients. Anesth Analg 2008; 106:171-4, table of contents. [PMID: 18165574 DOI: 10.1213/01.ane.0000297440.52059.2c] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Conventional thermodilution cardiac output (CO) monitoring is limited mainly to intensive care units and operating rooms because it requires the use of invasive techniques. To reduce the potential for complications and to broaden the applicability of hemodynamic monitoring, noninvasive methods for CO determination are being sought. Applanation tonometry allows noninvasive CO estimation through pulse contour analysis, but the method has not been evaluated in critically ill patients. We therefore performed noninvasive radial artery applanation tonometry in 49 critically ill medical intensive care unit patients and compared CO estimates to invasive CO measurements obtained using a pulmonary artery catheter or the PiCCO transpulmonary thermodilution system. One-hundred-sixteen measurements were performed, and patients were receiving vasopressor support during 78 measurements. When the data were analyzed with bias and precision statistics, a large bias of 2.03 L x min(-1) x m(-2) and a high percentage error of 85% were found between the invasive measurements and applanation tonometry-derived CO estimates, with the noninvasive CO results being significantly lower than the invasive ones (P < 0.001). There was no significant difference in bias between the patients who were receiving vasopressor support and those who were not (P = 0.874) or between patients with good and poor applanation tonometry pressure waveform signal quality (P = 0.071). Whereas a significant increase in the invasively determined CO was observed when a fluid bolus was administered (n = 7, P = 0.016), these changes were not reflected by the noninvasive method. We conclude that radial artery applanation tonometry is not suitable to determine CO in critically ill hemodynamically unstable patients.
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105
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Wittrock M, Scholze A, Compton F, Schaefer JH, Zidek W, Tepel M. Noninvasive pulse wave analysis for the determination of central artery stiffness. Microvasc Res 2008; 77:109-12. [PMID: 18996402 DOI: 10.1016/j.mvr.2008.10.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 09/21/2008] [Accepted: 10/02/2008] [Indexed: 01/08/2023]
Abstract
Central artery stiffness predicts cardiovascular structural damage and clinical outcome. It is controversial whether central artery stiffness can be determined by noninvasive measurements. We compared noninvasive determination of central artery stiffness obtained from applanation tonometry of the peripheral radial artery waveform with invasive measurements of the ratio of pulse-pressure-to-stroke-volume. A total of 112 invasive measurements of the ratio of pulse-pressure-to-stroke-volume and noninvasive determinations of central artery stiffness were performed in 49 patients on the intensive care unit. In 13 out of 112 attempts of noninvasive measurements (12%) radial pulse could not be obtained using applanation tonometry because of cardiac arrhythmia or radial pulse could not be detected. These 13 failing noninvasive measurements were attempted in 7 patients. In the remaining cases we found a significant correlation between noninvasively obtained central artery stiffness and invasive measurements of the ratio of pulse-pressure-to-stroke-volume (Spearman r=0.40; p<0.0001). The association between invasive and noninvasive measurements was confirmed using Bland-Altman plots. Furthermore, a norepinephrine-induced increase of arterial stiffness was detected both invasively and noninvasively. Noninvasive determination of central artery stiffness obtained from peripheral radial artery waveform should be useful in clinical practice although it cannot be performed in every patient.
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Tepel M, Roerig P, Wolter M, Gutmann DH, Perry A, Reifenberger G, Riemenschneider MJ. Frequent promoter hypermethylation and transcriptional downregulation of the NDRG2 gene at 14q11.2 in primary glioblastoma. Int J Cancer 2008; 123:2080-6. [PMID: 18709645 DOI: 10.1002/ijc.23705] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The N-myc downstream-regulated gene 2 (NDRG2) at 14q11.2 has been reported to be downregulated in glioblastoma, and NDRG2 overexpression represses glioblastoma cell proliferation in vitro (Deng et al., Int J Cancer 2003;106;342-7). To further address the role of NDRG2 as a candidate tumor suppressor in human gliomas, we analyzed 67 astrocytic tumors (10 diffuse astrocytomas, 11 anaplastic astrocytomas, 34 primary glioblastomas and 12 secondary glioblastomas) for NDRG2 gene mutation, promoter methylation and expression at the mRNA and protein levels. Using real-time reverse transcription PCR analysis, we found decreased NDRG2 mRNA levels in primary glioblastomas as compared to diffuse and anaplastic astrocytomas. Similarly, immunohistochemistry revealed low or absent NDRG2 protein expression in primary glioblastomas. Mutational analysis of the entire NDRG2 coding sequence did not reveal any tumor-associated DNA sequence alterations. However, sequencing of sodium bisulfite-modified DNA identified hypermethylation of the NDRG2 promoter region in 21 of 34 primary glioblastomas (62%). Moreover, NDRG2 promoter hypermethylation was associated with decreased NDRG2 mRNA expression. In contrast to primary glioblastomas, NDRG2 promoter hypermethylation was detected in only 1 of 11 anaplastic astrocytomas (9%) and was absent in 10 diffuse astrocytomas and 12 secondary glioblastomas. Taken together, our data support NDRG2 as a candidate tumor suppressor gene that is epigenetically silenced in the majority of primary glioblastomas, but not in lower grade astrocytomas and secondary glioblastomas.
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Frey SK, Nagl B, Henze A, Raila J, Schlosser B, Berg T, Tepel M, Zidek W, Weickert MO, Pfeiffer AFH, Schweigert FJ. Isoforms of retinol binding protein 4 (RBP4) are increased in chronic diseases of the kidney but not of the liver. Lipids Health Dis 2008; 7:29. [PMID: 18752671 PMCID: PMC2533662 DOI: 10.1186/1476-511x-7-29] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2008] [Accepted: 08/27/2008] [Indexed: 11/10/2022] Open
Abstract
Background The levels of retinol-binding protein 4 (RBP4) – the carrier protein for Vitamin A in plasma – are tightly regulated under healthy circumstances. The kidney, the main site of RBP4 catabolism, contributes to an elevation of RBP4 levels during chronic kidney disease (CKD) whereas during chronic liver disease (CLD) RBP4 levels decrease. Little is known about RBP4 isoforms including apo-RBP4, holo-RBP4 as well as RBP4 truncated at the C-terminus (RBP4-L and RBP4-LL) except that RBP4 isoforms have been reported to be increased in hemodialysis patients. Since it is not known whether CLD influence RBP4 isoforms, we investigated RBP4 levels, apo- and holo-RBP4 as well as RBP4-L and RBP4-LL in plasma of 36 patients suffering from CKD, in 55 CLD patients and in 50 control subjects. RBP4 was determined by ELISA and apo- and holo-RBP4 by native polyacrylamide gel electrophoresis (PAGE). RBP4-L and RBP4-LL were analyzed after immunoprecipitation by mass spectrometry (MALDI-TOF-MS). Results RBP4 isoforms and levels were highly increased in CKD patients compared to controls (P < 0.05) whereas in CLD patients RBP4 isoforms were not different from controls. In addition, in hepatic dysfunction RBP4 levels were decreased whereas the amount of isoforms was not affected. Conclusion The occurrence of RBP4 isoforms is not influenced by liver function but seems to be strongly related to kidney function and may therefore be important in investigating kidney function and related disorders.
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Tepel M, Hopfenmueller W, Scholze A, Maier A, Zidek W. Effect of amlodipine on cardiovascular events in hypertensive haemodialysis patients. Nephrol Dial Transplant 2008; 23:3605-12. [PMID: 18511605 PMCID: PMC2568006 DOI: 10.1093/ndt/gfn304] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Hypertensive haemodialysis patients may be at a high risk for cardiovascular events. This study was undertaken to ascertain whether the calcium channel blocker amlodipine reduces mortality and cardiovascular events in these high-risk patients. METHODS We evaluated the effects of amlodipine on cardiovascular events in 251 hypertensive haemodialysis patients in an investigator-designed, prospective, randomized, double-blind, placebo-controlled, multicenter trial. One hundred and twenty-three patients were randomly assigned to amlodipine (10 mg once daily) and 128 to placebo. The primary endpoint was mortality from any cause. The secondary endpoint was a composite variable consisting of mortality from any cause or cardiovascular event. Analysis was by intention-to-treat. The trial was registered with ClinicalTrials.gov (number NCT00124969). RESULTS The median age of patients was 61 years (25% percentile - 75% percentile, 47-69), and the median follow-up was 19 months (8-30). Fifteen (12%) of the 123 patients assigned to amlodipine and 22 (17%) of the 128 patients assigned to placebo had a primary endpoint [hazard ratio 0.65 (95% CI 0.34-1.23); P = 0.19]. Nineteen (15%) of the 123 haemodialysis patients assigned to amlodipine and 32 (25%) of the 128 haemodialysis patients assigned to placebo reached the secondary composite endpoint [hazard ratio 0.53 (95% CI 0.31-0.93); P = 0.03]. CONCLUSION Amlodipine safely reduces systolic blood pressure and it may have a beneficial effect on cardiovascular outcomes in hypertensive haemodialysis patients.
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Liu D, Maier A, Scholze A, Rauch U, Boltzen U, Zhao Z, Zhu Z, Tepel M. High Glucose Enhances Transient Receptor Potential Channel Canonical Type 6–Dependent Calcium Influx in Human Platelets via Phosphatidylinositol 3-Kinase–Dependent Pathway. Arterioscler Thromb Vasc Biol 2008; 28:746-51. [DOI: 10.1161/atvbaha.108.162222] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
Transient receptor potential canonical type 6 (TRPC6) channels mediating 1-oleoyl-2-acetyl-sn-glycerol (OAG)–induced calcium entry have been identified on human platelets. In the present study we tested the hypothesis that hyperglycemia increases the expression of TRPC6 channels.
Methods and Results—
Platelets from healthy control subjects and patients with type 2 diabetes mellitus were incubated with glucose and calcium influx was measured using the fluorescent dye technique. TRPC channel protein expression was investigated using immunofluorescence and fluorescence microscopy of single platelets. Administration of 25 mmol/L glucose significantly enhanced the OAG-induced calcium influx, which was attenuated by inhibitors of the phosphatidylinositol 3-kinase, wortmannin or LY294002. The glucose-enhanced and OAG-induced calcium influx was concentration- and time-dependent. Glucose significantly increased the TRPC6 protein expression in platelets to 131±12% (n=33;
P
<0.05), whereas the expression of TRPC1, TRPC3, TRPC4, or TRPC5 were unchanged. The glucose-induced TRPC6 expression was significantly attenuated in the presence of wortmannin or LY294002. Platelets from patients with type 2 diabetes mellitus showed increased TRPC6 expression compared to nondiabetic individuals (
P
<0.05).
Conclusion—
The study indicates that high glucose increases TRPC6 channel protein expression on the platelet surface which is mediated by a phosphatidylinositol 3-kinase–dependent pathway.
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Abstract
Leptin is mainly produced by adipocytes and metabolized in the kidney. Leptin is taken up into the central nervous system by a saturable transport system, and controls appetite in rodents and in healthy subjects. Leptin acts on peripheral tissue and increases the inflammatory response by stimulating the production of tumor necrosis factor alpha, interleukin-6 and interleukin-12. In healthy humans, serum leptin concentration is related to the size of adipose tissue mass in the body. The majority of obese subjects have inappropriately high levels of circulating plasma leptin concentrations, indicating leptin resistance. In healthy subjects increased leptin concentration constitutes a biomarker for increased cardiovascular risk. On the other hand, a recent prospective long-term study in patients with chronic kidney disease stage 5 on hemodialysis therapy showed that reduced serum leptin concentration is an independent risk factor for mortality in these patients.
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Tepel M. Does prophylactic haemodialysis protect kidney function after angiography? Nephrol Dial Transplant 2008; 23:1473-5. [PMID: 18227136 DOI: 10.1093/ndt/gfn019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Thilo F, Scholze A, Liu DY, Zidek W, Tepel M. Association of transient receptor potential canonical type 3 (TRPC3) channel transcripts with proinflammatory cytokines. Arch Biochem Biophys 2007; 471:57-62. [PMID: 18177730 DOI: 10.1016/j.abb.2007.12.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2007] [Revised: 12/10/2007] [Accepted: 12/11/2007] [Indexed: 10/22/2022]
Abstract
We investigated whether expression of non-selective cation channels of the transient receptor potential canonical (TRPC) channel family are associated with proinflammatory cytokines in monocytes. Using quantitative RT-PCR we studied the expression of TRPC3, interleukin-1beta (IL-1beta), and tumor necrosis factor-alpha (TNF-alpha) in monocytes from 15 patients with essential hypertension and 16 age- and sex-matched normotensive control subjects. We observed an approximately 8-fold increase of TRPC3 transcripts in monocytes from patients with essential hypertension compared to normotensive control subjects (p<0.05). We found an approximately 3-fold increase of IL-1beta, and an approximately 9-fold increase of TNF-alpha in patients with essential hypertension compared to normotensive control subjects (each p<0.05). We observed a significant correlation between TRPC3 transcripts with systolic blood pressure, expression of IL-1beta, and TNF-alpha. Using quantitative RT-PCR we observed an association of TRPC3 transcripts and proinflammatory cytokines in monocytes.
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Zhao Z, Nie H, He H, Yan Z, Liu D, Luo Z, Ma L, Ni Y, Chen J, Jing J, Cao T, Yang H, Tepel M, Zhang W, Zhu Z. High-sensitivity C-reactive protein predicts target organ damage in Chinese patients with metabolic syndrome. Metabolism 2007; 56:1612-9. [PMID: 17998010 DOI: 10.1016/j.metabol.2007.06.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Accepted: 06/04/2007] [Indexed: 10/22/2022]
Abstract
Observational studies established high-sensitivity C-reactive protein as a risk factor for cardiovascular events in the general population. The goal of this study was to determine the relationship between target organ damage and high-sensitivity C-reactive protein in a cohort of Chinese patients with metabolic syndrome. A total of 1082 consecutive patients of Chinese origin were screened for the presence of metabolic syndrome according to the National Cholesterol Education Program's Adult Treatment Panel III. High-sensitivity C-reactive protein and target organ damage, including cardiac hypertrophy, carotid intima-media thickness, and renal impairment, were investigated. The median (25th and 75th percentiles) of high-sensitivity C-reactive protein in 619 patients with metabolic syndrome was 2.42 mg/L (0.75 and 3.66 mg/L) compared with 1.13 mg/L (0.51 and 2.46 mg/L) among 463 control subjects (P < .01). There was a progressive increase in high-sensitivity C-reactive protein level with the number of components of the metabolic syndrome. Stratification of patients with metabolic syndrome into 3 groups according to their high-sensitivity C-reactive protein concentrations (<1.0, 1.0-3.0, and >3.0 mg/L) showed that the subjects with the elevated high-sensitivity C-reactive protein had a higher percentage of target organ damage than those with lower high-sensitivity C-reactive protein. Stepwise multiple logistic regression confirmed that high-sensitivity C-reactive protein was significantly associated with cardiac hypertrophy, carotid intima-media thickness, and renal impairment. The study shows a strong independent association between inflammation and target organ damage in a large cohort of patients of Chinese origin with metabolic syndrome.
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Tepel M, Zidek W. Rolle der Transient-Receptor-Potential-Kanäle im kardiovaskulären System. Dtsch Med Wochenschr 2007; 132:2442-4. [DOI: 10.1055/s-2007-991670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Tetzner F, Scholze A, Wittstock A, Zidek W, Tepel M. Impaired vascular reactivity in patients with chronic kidney disease. Am J Nephrol 2007; 28:218-23. [PMID: 17960060 DOI: 10.1159/000110091] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2007] [Accepted: 09/13/2007] [Indexed: 12/13/2022]
Abstract
BACKGROUND Patients with chronic kidney disease (CKD) show increased cardiovascular morbidity. We hypothesized that vascular properties which can be routinely evaluated noninvasively are related to different stages of CKD and their clinical and biochemical characteristics. METHODS Arterial vascular properties were quantified by the reflective index using digital photoplethysmography in 260 patients with CKD. Patients were grouped according to estimated glomerular filtration rate (eGFR). Additional measurements were performed in 50 healthy control subjects. RESULTS In patients with CKD stage 1 and 2 (n = 115; age 65 +/- 1 years) the reflective index was 30 +/- 1%, whereas in patients with CKD stage 3 and 4 (n = 60; age 72 +/- 1 years) the reflective index was 36 +/- 1%, and in patients with CKD stage 5 (n = 85; age 64 +/- 1 years) the reflective index was 36 +/- 1% (p < 0.01 by Kruskal-Wallis test) indicating increased arterial stiffness in advanced CKD. Arterial vascular reactivity was significantly impaired in patients with advanced stages of CKD (stage 1 and 2, 78 +/- 12%; stage 3 and 4, 32 +/- 12%; stage 5, 33 +/- 12%; p < 0.01). Univariate analysis showed a significant correlation of the reflective index and eGFR (Pearson r = -0.24; p < 0.0001). Multivariate regression analysis showed an independent association of the reflective index and eGFR (adjusted correlation coefficient, -0.24; p < 0.001). CONCLUSION The advanced stages of CKD are associated with increased vascular stiffness and impaired vascular reactivity and these changes are already present in CKD stage 3 and 4.
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Liu DY, Scholze A, Kreutz R, Wehland-von-Trebra M, Zidek W, Zhu ZM, Tepel M. Monocytes from spontaneously hypertensive rats show increased store-operated and second messenger-operated calcium influx mediated by transient receptor potential canonical Type 3 channels. Am J Hypertens 2007; 20:1111-8. [PMID: 17903696 DOI: 10.1016/j.amjhyper.2007.04.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Revised: 04/02/2007] [Accepted: 04/05/2007] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND We recently showed that increased expression of the transient receptor potential canonical Type 3 (TRPC3) channel is associated with genetic hypertension. It is unknown whether store-operated TRPC3 channels, which are activated after depletion of intracellular stores, or second messenger-operated TRPC3 channels, which are activated by 1-oleoyl-2-acetyl-sn-glycerol, show augmented responses in monocytes in genetic hypertension and support the development of vascular disease. METHODS Using the fluorescent-dye technique, we studied store-depleted and thapsigargin-induced, store-operated calcium influx and 1-oleoyl-2-acetyl-sn-glycerol-induced second messenger-operated calcium influx into monocytes from spontaneously hypertensive rats (SHRs) and from normotensive Wistar-Kyoto rats (WKYs). The RNA interference for the downregulation of TRPC3 in monocytes by small, interfering RNA (siRNA) was performed and evaluated using in-cell Western assay. RESULTS Thapsigargin-induced, store-operated calcium influx was significantly elevated in SHRs and was approximately double that observed in WKYs. In the presence of nimodipine, the thapsigargin-induced, store-operated calcium influx was also significantly higher in SHRs compared with WKYs. After stimulation of monocytes by angiotensin II, calcium influx was significantly elevated in SHRs, and was approximately double that observed in WKYs. The 1-oleoyl-2-acetyl-sn-glycerol-induced, second messenger-operated calcium influx was also significantly elevated in SHRs compared with WKYs. Thapsigargin-induced, store-operated calcium influx was reduced by the inhibitor 2-aminoethoxydiphenyl borane. After TRPC3 knockdown, the thapsigargin-induced, store-operated calcium influx, as well as 1-oleoyl-2-acetyl-sn-glycerol-induced calcium influx, was significantly more reduced in cells from SHRs compared with WKYs. CONCLUSIONS The increased store-operated and second messenger-operated calcium influx through TRPC3 channels in monocytes from SHRs may be responsible for a more aggressive effect in promoting vascular disease in genetic hypertension.
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Abstract
Prevention of ototoxicity after the administration of aminoglycoside antibiotics has been notably difficult, in particular in patients with chronic kidney disease. Feldman et al. report that oral administration of 600 mg N-acetylcysteine twice daily significantly ameliorates gentamicin-induced ototoxicity in hemodialysis patients. That approach may help to prevent aminoglycoside-induced hearing loss in these high-risk patients in daily practice.
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Scholze A, Jankowski V, Henning L, Haass W, Wittstock A, Suvd-Erdene S, Zidek W, Tepel M, Jankowski J. Phenylacetic acid and arterial vascular properties in patients with chronic kidney disease stage 5 on hemodialysis therapy. Nephron Clin Pract 2007; 107:c1-6. [PMID: 17622769 DOI: 10.1159/000105137] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Accepted: 03/20/2007] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Phenylacetic acid (PAA) is a recently described uremic toxin that inhibits inducible nitric oxide synthase expression and plasma membrane calcium ATPase and may therefore also be involved in remodeling of arteries. Such vascular effects have not been evaluated yet in patients with chronic kidney disease stage 5. METHOD We prospectively measured the plasma concentrations of PAA using nuclear magnetic resonance spectroscopy in 50 patients with chronic kidney disease stage 5 (37 men, 13 women) on maintenance hemodialysis. Arterial vascular properties were quantified by the reflective index obtained from digital photoplethysmography. RESULTS During the hemodialysis session the plasma PAA concentration was reduced from 3.38 +/- 0.24 mmol/l (mean +/- SEM; median, 2.85 mmol/l; interquartile range, 2.02-4.52 mmol/l) to 2.25 +/- 0.11 mmol/l (median, 2.06 mmol/l; interquartile range, 1.62-2.86 mmol/l; n = 50; p < 0.001). There was a significant correlation between the PAA concentration and the reflective index before the start of the hemodialysis session. CONCLUSION The study demonstrates an association of PAA and arterial vascular properties in patients with chronic kidney disease stage 5.
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Scholze A, Rattensperger D, Zidek W, Tepel M. Low serum leptin predicts mortality in patients with chronic kidney disease stage 5. Obesity (Silver Spring) 2007; 15:1617-22. [PMID: 17558000 DOI: 10.1038/oby.2007.191] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Leptin, secreted from adipose tissue, regulates food intake, energy expenditure, and immune function. It is unknown whether leptin predicts mortality in patients with chronic kidney disease stage 5 on hemodialysis therapy. RESEARCH METHODS AND PROCEDURES We performed a prospective cohort study of 71 patients with chronic kidney disease stage 5 in an outpatient hemodialysis center. Subjects were recruited in June 1998 and followed for 83 months. Survival was compared by the Kaplan-Meier method. RESULTS After 83 months of follow-up, 48 patients (68%) had died. Serum leptin concentrations at study entry were lower among all deceased patients compared with those patients who survived (5.2 +/- 9.0 microg/L; n = 48; vs. 7.7 +/- 7.8 microg/L; n = 23; p = 0.005). Baseline serum leptin concentrations were significantly lower in patients who died from cardiovascular diseases (4.7 +/- 9.4 microg/L, n = 32) or infections (4.0 +/- 2.7 microg/L; n = 10; each p < 0.05), but not cancer (9.4 +/- 7.9 microg/L; n = 6), than in survivors (7.7 +/- 7.8 microg/L; n = 23; p = 0.003). The relative risk for mortality in patients with serum leptin concentrations below the median (<2.6 microg/L) compared with patients above the median was 1.96 (95% confidence interval, 1.01 to 3.79; p = 0.04). Survival was shorter in patients with leptin concentrations below the median compared with those whose leptin concentrations were above the median (all-cause mortality, chi(2) = 5.05; p = 0.02). DISCUSSION Low serum leptin concentration is an independent predictor of mortality in patients with chronic kidney disease stage 5 on hemodialysis therapy.
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Kiewe P, Tepel M, Loddenkemper C, Grünbaum M, Grabowski P, Korfel A, Thiel E. Extensive leukemic kidney infiltration with membranoproliferative glomerulonephritis in a patient with B-cell chronic lymphocytic leukemia. Ann Hematol 2007; 86:691-2. [PMID: 17447066 DOI: 10.1007/s00277-007-0293-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Accepted: 03/29/2007] [Indexed: 10/23/2022]
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Liu DY, Thilo F, Scholze A, Wittstock A, Zhao ZG, Harteneck C, Zidek W, Zhu ZM, Tepel M. Increased store-operated and 1-oleoyl-2-acetyl-sn-glycerol-induced calcium influx in monocytes is mediated by transient receptor potential canonical channels in human essential hypertension. J Hypertens 2007; 25:799-808. [PMID: 17351372 DOI: 10.1097/hjh.0b013e32803cae2b] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Activation of nonselective cation channels of the transient receptor potential canonical (TRPC) family has been associated with hypertension. Whether store-operated channels, which are activated after depletion of intracellular stores, or second-messenger-operated channels, which are activated by 1-oleoyl-2-acetyl-sn-glycerol, are affected in essential hypertension is presently unknown. METHODS Using a polymerase chain reaction, an in-cell western assay and the fluorescent dye technique we studied TRPC3, TRPC5, and TRPC6 expression and store-operated and 1-oleoyl-2-acetyl-sn-glycerol-induced calcium influx into human monocytes in 19 patients with essential hypertension and in 17 age-matched and sex-matched normotensive control individuals. RESULTS We observed a significantly increased expression of TRPC3 and TRPC5, but not TRPC6, in essential hypertension. Store-operated calcium influx was significantly elevated in essential hypertension. Store-operated calcium influx was reduced by the inhibitor 2-aminoethoxydiphenylborane, specific TRPC3 and TRPC5 knockdown, but not TRPC6 knockdown using gene silencing by RNA interference. 1-Oleoyl-2-acetyl-sn-glycerol-induced calcium influx and barium influx were also significantly elevated in essential hypertension. The 1-oleoyl-2-acetyl-sn-glycerol-induced cation influx was reduced by TRPC3 and TRPC5 knockdown. CONCLUSION We demonstrated an increased TRPC3 and TRPC5 expression and a subsequently increased store-operated calcium influx and increased 1-oleoyl-2-acetyl-sn-glycerol-induced cation influx in monocytes of patients with essential hypertension. This increased activation of monocytes through TRPC channels in patients with essential hypertension may promote vascular disease in these patients.
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Zhang LL, Yan Liu D, Ma LQ, Luo ZD, Cao TB, Zhong J, Yan ZC, Wang LJ, Zhao ZG, Zhu SJ, Schrader M, Thilo F, Zhu ZM, Tepel M. Activation of transient receptor potential vanilloid type-1 channel prevents adipogenesis and obesity. Circ Res 2007; 100:1063-70. [PMID: 17347480 DOI: 10.1161/01.res.0000262653.84850.8b] [Citation(s) in RCA: 305] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We tested the hypothesis that activation of transient receptor potential vanilloid type-1 (TRPV1) by capsaicin prevents adipogenesis. TRPV1 channels in 3T3-L1-preadipocytes and visceral adipose tissue from mice and humans were detected by immunoblotting and quantitative real-time RT-PCR. The effect of TRPV1 on cytosolic calcium was determined fluorometrically in 3T3-L1-preadipocytes and in human visceral fat tissue. Adipogenesis in stimulated 3T3-L1-preadipocytes was determined by oil red O-staining of intracellular lipid droplets, triglyceride levels, expression of peroxisome proliferator-activated receptor-gamma, and expression of fatty acid synthase. Long-term feeding experiments were undertaken in wild-type mice and TRPV1 knockout mice. We detected TRPV1 channels in 3T3-L1-preadipocytes and visceral adipose tissue from mice and humans. In vitro, the TRPV1 agonist capsaicin dose-dependently induced calcium influx and prevented the adipogenesis in stimulated 3T3-L1-preadipocytes. RNA interference knockdown of TRPV1 in 3T3-L1-preadipocytes attenuated capsaicin-induced calcium influx, and adipogenesis in stimulated 3T3-L1-preadipocytes was no longer prevented. During regular adipogenesis TRPV1 channels were downregulated which was accompanied by a significant and time-dependent reduction of calcium influx. Compared with lean counterparts in visceral adipose tissue from obese db/db and ob/ob mice, and from obese human male subjects we observed a reduced TRVP1 expression. The reduced TRPV1 expression in visceral adipose tissue from obese humans was accompanied by reduced capsaicin-induced calcium influx. The oral administration of capsaicin for 120 days prevented obesity in male wild type mice but not in TRPV1 knockout mice assigned to high fat diet. We conclude that the activation of TRPV1 channels by capsaicin prevented adipogenesis and obesity.
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Schlüter H, Rykl J, Thiemann J, Kurzawski S, Gobom J, Tepel M, Zidek W, Linscheid M. Mass Spectrometry-Assisted Protease Substrate Screening. Anal Chem 2007; 79:1251-5. [PMID: 17263361 DOI: 10.1021/ac061482l] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Since sequencing of the human genome was completed, more than 500 genes have been annotated as proteases. Exploring the physiological role of each protease requires the identification of their natural substrates. However, the endogenous substrates of many of the human proteases are as yet unknown. Here we describe a new assay that addresses this problem. The assay, which easily can be automated, is based on the incubation of immobilized protein fractions, which may contain the natural substrate, with a defined protease. After concentrating the proteolytically released peptides by reversed-phase chromatography they are analyzed by tandem mass spectrometry and the substrates identified by database searching. The proof of principle in this study is demonstrated by incubating immobilized human plasma proteins with thrombin and by identifying by tandem mass spectrometry the fibrinopeptides, released by the action of thrombin from their natural substrate fibrinogen, in the reaction mixture.
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Yan ZC, Liu DY, Zhang LL, Shen CY, Ma QL, Cao TB, Wang LJ, Nie H, Zidek W, Tepel M, Zhu ZM. Exercise reduces adipose tissue via cannabinoid receptor type 1 which is regulated by peroxisome proliferator-activated receptor-delta. Biochem Biophys Res Commun 2007; 354:427-33. [PMID: 17223076 DOI: 10.1016/j.bbrc.2006.12.213] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2006] [Accepted: 12/29/2006] [Indexed: 11/15/2022]
Abstract
Obesity is one major cardiovascular risk factor. We tested effects of endurance exercise on cannabinoid receptor type 1 (CB1) and peroxisome proliferator-activated receptor-delta (PPAR-delta)-dependent pathways in adipose tissue. Male Wistar rats were randomly assigned to standard laboratory chow or a high-fat diet without and with regular endurance exercise. Exercise in rats on high-fat diet significantly reduced visceral fat mass, blood pressure, and adipocyte size (each p<0.05). Adipocyte hypertrophy induced by high-fat diet was accompanied by increased CB1 expression in adipose tissue, whereas exercise significantly reduced CB1 expression (each p<0.05). CB1 receptor expression and adipocyte differentiation were directly regulated by PPAR-delta. Adipocyte hypertrophy induced by high-fat diet was accompanied by reduced PPAR-delta. Furthermore, selective silencing of PPAR-delta by RNA interference in 3T3-L1-preadipocyte cells significantly increased CB1 expression from 1.00+/-0.06 (n=3) to 1.91+/-0.06 (n=3; p<0.01) and increased adipocyte differentiation, whereas adenovirus-mediated overexpression of PPAR-delta significantly reduced CB1 expression to 0.39+/-0.03 (n=3; p<0.01) and reduced adipocyte differentiation. In the presence of the CB1 antagonist rimonabant adipocyte differentiation in stimulated 3T3 L1 preadipocyte cells was significantly reduced. The study indicates that high-fat diet-induced hypertrophy of adipocytes is associated with increased CB1 receptor expression which is directly regulated by PPAR-delta. Both CB1 and PPAR-delta are intimately involved in therapeutic interventions against a most important cardiovascular risk factor.
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Jankowski V, Vanholder R, van der Giet M, Tölle M, Karadogan S, Gobom J, Furkert J, Oksche A, Krause E, Tran TNA, Tepel M, Schuchardt M, Schlüter H, Wiedon A, Beyermann M, Bader M, Todiras M, Zidek W, Jankowski J. Mass-spectrometric identification of a novel angiotensin peptide in human plasma. Arterioscler Thromb Vasc Biol 2006; 27:297-302. [PMID: 17138938 DOI: 10.1161/01.atv.0000253889.09765.5f] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Angiotensin peptides play a central role in cardiovascular physiology and pathology. Among these peptides, angiotensin II (Ang II) has been investigated most intensively. However, further angiotensin peptides such as Ang 1-7, Ang III, and Ang IV also contribute to vascular regulation, and may elicit additional, different, or even opposite effects to Ang II. Here, we describe a novel Ang II-related, strong vasoconstrictive substance in plasma from healthy humans and end-stage renal failure patients. METHODS AND RESULTS Chromatographic purification and structural analysis by matrix-assisted laser desorption/ionisation time-of-flight/time-of-flight (MALDI-TOF/TOF) revealed an angiotensin octapeptide with the sequence Ala-Arg-Val-Tyr-Ile-His-Pro-Phe, which differs from Ang II in Ala1 instead of Asp1. Des[Asp1]-[Ala1]-Ang II, in the following named Angiotensin A (Ang A), is most likely generated enzymatically. In the presence of mononuclear leukocytes, Ang II is converted to Ang A by decarboxylation of Asp1. Ang A has the same affinity to the AT1 receptor as Ang II, but a higher affinity to the AT2 receptor. In the isolated perfused rat kidney, Ang A revealed a smaller vasoconstrictive effect than Ang II, which was not modified in the presence of the AT2 receptor antagonist PD 123319, suggesting a lower intrinsic activity at the AT1 receptor. Ang II and Ang A concentrations in plasma of healthy subjects and end-stage renal failure patients were determined by matrix-assisted laser desorption/ionisation mass-analysis, because conventional enzyme immunoassay for Ang II quantification did not distinguish between Ang II and Ang A. In healthy subjects, Ang A concentrations were less than 20% of the Ang II concentrations, but the ratio Ang A/Ang II was higher in end-stage renal failure patients. CONCLUSIONS Ang A is a novel human strong vasoconstrictive angiotensin-derived peptide, most likely generated by enzymatic transformation through mononuclear leukocyte-derived aspartate decarboxylase. Plasma Ang A concentration is increased in end-stage renal failure. Because of its stronger agonism at the AT2 receptor, Ang A may modulate the harmful effects of Ang II.
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