Juliane Bolbrinker

Comparative expression analysis of the renin–angiotensin system components between white and brown perivascular adipose tissue

Recent studies have demonstrated that the rat adipose tissue expresses some of the components necessary for the production of angiotensin II (Ang II) and the receptors mediating its actions. The aim of this work is to characterize the expression of the renin-angiotensin system (RAS) components in perivascular adipose tissue and to assess differences in the expression pattern depending on the vascular bed and type of adipose tissue. We analyzed Ang I and Ang II levels as well as mRNA levels of RAS components by a quantitative RT-PCR method in periaortic (PAT) and mesenteric adipose tissue (MAT) of 3-month-old male Wistar-Kyoto rats. PAT was identified as brown adipose tissue expressing uncoupling protein-1 (UCP-1). It had smaller adipocytes than those from MAT, which was identified as white adipose tissue. All RAS components, except renin, were detected in both PAT and MAT. Levels of expression of angiotensinogen, Ang-converting enzyme (ACE), and ACE2 were similar between PAT and MAT. Renin receptor expression was five times higher, whereas expression of chymase, AT(1a), and AT(2) receptors were significantly lower in PAT compared with MAT respectively. In addition, three isoforms of the AT(1a) receptor were found in perivascular adipose tissue. The AT(1b) receptor was found at very a low expression level. Ang II levels were higher in MAT with no differences between tissues in Ang I. The results show that the RAS is differentially expressed in white and brown perivascular adipose tissues implicating a different role for the system depending on the vascular bed and the type of adipose tissue.

Anticontractile Effect of Perivascular Adipose Tissue and Leptin are Reduced in Hypertension

Leptin causes vasodilatation both by endothelium-dependent and -independent mechanisms. Leptin is synthesized by perivascular adipose tissue (PVAT). The hypothesis of this study is that a decrease of leptin production in PVAT of spontaneously hypertensive rats (SHR) might contribute to a diminished paracrine anticontractile effect of the hormone. We have determined in aorta from Wistar-Kyoto (WKY) and SHR (i) leptin mRNA and protein levels in PVAT, (ii) the effect of leptin and PVAT on contractile responses, and (iii) leptin-induced relaxation and nitric oxide (NO) production. Leptin mRNA and protein expression were significantly lower in PVAT from SHR. Concentration-response curves to angiotensin II were significantly blunted in presence of PVAT as well as by exogenous leptin (10−9 M) only in WKY. This anticontractile effect was endothelium-dependent. Vasodilatation induced by leptin was smaller in SHR than in WKY, and was also endothelium-dependent. Moreover, release of endothelial NO in response to acute leptin was higher in WKY compared to SHR, but completely abolished in the absence of endothelium. In conclusion, the reduced anticontractile effect of PVAT in SHR might be attributed to a reduced PVAT-derived leptin and to an abrogated effect of leptin on endothelial NO release probably due to an impaired activation of endothelial NO synthase.

Expression and Response to Angiotensin-Converting Enzyme Inhibition of Matrix Metalloproteinases 2 and 9 in Renal Glomerular Damage in Young Transgenic Rats with Renin-Dependent Hypertension

Extracellular matrix expansion in the glomerular mesangium contributes to the development of glomerulosclerosis and chronic renal disease in arterial hypertension. Transforming growth factor-β1 (TGF-β1), matrix metalloproteinases (MMPs), and tissue inhibitors of MMPs (TIMPs) are involved in this process. Conflicting data are reported on the effects of angiotensin II (Ang II) and the response to angiotensin-converting enzyme inhibition on MMPs and TIMPs in early stages of hypertensive glomerular damage. We therefore investigated the effects of Ang II-dependent hypertension on MMP-2, MMP-9, TIMP-1, and TIMP-2 in isolated glomeruli of 8-week-old homozygous male rats overexpressing the mouse Ren2 gene [TGR(mRen2)27]. At this age, systolic blood pressure was already significantly elevated in Ren2 compared with Sprague-Dawley (SD) rats (197 ± 38 versus 125 ± 16 mm Hg, p < 0.01). Ren2 exhibited renal damage as determined by increased urinary albumin excretion, focal glomerulosclerosis, mesangial matrix expansion, and α-smooth muscle actin deposition. Quantification of mRNA levels in isolated glomeruli by real-time polymerase chain reaction showed a significant increase of TGF-β1, a 2.3- and a 2.6-fold increase of MMP-2 and TIMP-1 in Ren2 compared with SD (p < 0.01, respectively) and no strain differences for TIMP-2. In contrast, MMP-9 mRNA expression was markedly suppressed to 10% of control levels in Ren2 (p < 0.01). Early treatment with ramipril completely prevented renal damage in Ren2 and restored mRNA expression of TGF-β1, MMP-2, and TIMP-1 to SD control levels. Interestingly, down-regulation of MMP-9 mRNA, protein, and activity was not affected by ramipril, indicating that the protective effect of this compound is not attributable to restoration of MMP-9 in the glomerulus.

Antipsychotic drugs predominate in pharmacotherapy of nursing home residents with dementia.

INTRODUCTION The aim of this study was to investigate the frequency of benzodiazepines, antidementia and antipsychotic drug prescriptions in nursing home residents (NHR).Data of a German health insurance company were retrospectively analyzed for the year 2008. METHODS The study cohort comprised 13,042 NHR (82% women, mean age 83.6 ± 7 years). Following analgetics, antipsychotic drugs were the second most frequently prescribed drug group with 13.3% of all prescriptions. Dementia was diagnosed in 8 017 (61.5%) NHR. Thereof 51.6% received an antipsychotic, 17.3% a benzodiazepine and 15.2% an antidementia pharmaceutical, respectively. 18.1% of NHR with dementia and antipsychotic drug prescriptions were in combined treatment with antidementia pharmaceuticals. The rate of antipsychotic drug prescribing was significantly doubled in NHR with dementia compared to those without this diagnosis (p<0.01); the most frequently prescribed antipsychotics were melperone, risperidone and pipamperone. DISCUSSION This study demonstrates the wide-spread use of psychotropic drugs in NHR. Moreover, dementia in NHR was associated with antipsychotic drug prescribing in every second patient. This highlights the need for further studies analyzing alternative treatments for dementia-related symptoms.

Prescribing of inappropriate medication in nursing home residents in Germany according to a French consensus list: a cross-sectional cohort study

The current use of inappropriate medication in elderly nursing home residents (NHRs) in Germany is unclear. We therefore set out to analyse the frequency and patterns of potentially inappropriate drug prescriptions in elderly NHRs in Germany.

Pharmacokinetics of Olmesartan Medoxomil plus Hydrochlorothiazide Combination in Healthy Subjects

AbstractBackground: Hypertension treatment guidelines recommend combination therapy with diuretics and other antihypertensive agents, including angiotensin II type 1 (AT1) receptor antagonists. This trial investigated the possibility of pharmacokinetic interactions between the AT1 receptor antagonist olmesartan medoxomil and the thiazide diuretic hydrochlorothiazide in healthy subjects. Methods: Twenty-four healthy normotensive adult male subjects underwent three consecutive 7-day treatment periods (A, B and C, respectively) during which they were randomised to receive: olmesartan medoxomil 20mg once daily (regimen A), hydrochlorothiazide 25mg once daily (regimen B), or olmesartan medoxomil 20mg once daily plus hydrochlorothiazide 25mg once daily (regimen C). Treatment periods were separated by washouts of 7–14 days. The primary pharmacokinetic parameters evaluated were: the area under the plasma concentration versus time curve at steady state (AUCss,τ), the maximum plasma concentration at steady state (Css,max), and the time at which Css,max occurred (tmax). Results: Complete data sets from 17 subjects were available for pharmacokinetic analyses. Mean concentration versus time profiles were similar for monotherapy and combination treatment for both olmesartan (the active metabolite of olmesartan medoxomil) and hydrochlorothiazide. For olmesartan, comparison of monotherapy with combination therapy showed that for AUCss,τ and Css,max point estimates were close to unity, demonstrating bioequivalence. For hydrochlorothiazide, combination therapy resulted in decreases in AUCss,τ and Css,max of approximately 10% versus monotherapy; nevertheless, since 90% CIs were within the acceptance range, bioequivalence was proven. Median tmax values for olmesartan and hydrochlorothiazide for periods A, B and C were identical, indicating bioequivalence. Both olmesartan medoxomil and hydrochlorothiazide were well tolerated. Conclusion: These results show that there is little or no potential for a clinically relevant pharmacokinetic interaction between olmesartan medoxomil 20mg and hydrochlorothiazide 25mg, and therefore dosage adjustment should not be necessary when they are co-administered.

Genetic analysis of salt-sensitive hypertension in Dahl rats reveals a link between cardiac fibrosis and high cholesterol

AIMS Previously we confirmed an important role of rat chromosome 19 (RNO19) for salt-sensitive hypertension and target organ damage in male Dahl salt-sensitive rats (SS rats). The aim of this study was to further analyse the basis of left ventricular (LV) fibrosis development in both male and female rats in this model. To this end we utilized a consomic SS-19(SHR) rat strain in which RNO19 was transferred from spontaneously hypertensive rats (SHR) into the susceptible background of SS. METHODS AND RESULTS We compared the effects of low- (0.2% NaCl) and high-salt (4% NaCl) diet on the development of hypertension, blood lipids and LV fibrosis in male and female SS, SHR, and SS-19(SHR) rats. Systolic blood pressure was significantly lower in male and female SS-19(SHR) compared with SS under both diets (P < 0.001). Relative LV weight was similarly reduced in SS-19(SHR) compared with SS in either sex. Plasma cholesterol concentrations were significantly elevated in high-salt fed male and female SS (141 +/- 6 and 110 +/- 7 mg/dL) compared with SHR (47 +/- 2 and 62 +/- 8 mg/dL, P < 0.001) and were significantly lowered in male and female consomic rats (100 +/- 7 and 87 +/- 3 mg/dL). Both LV interstitial fibrosis (LVIF) and perivascular fibrosis (LVPF) were significantly reduced in high-salt male and female SS-19(SHR). A significant correlation between cholesterol concentrations and LVPF (r = 0.464) and LVIF (r = 0.401, P < 0.0001, respectively) was detected. Fibrosis parameters demonstrated no correlation with blood pressure, LV weight or plasma triglycerides concentrations. LV immunohistochemistry analysis showed a significant higher number of ED-1 positive cells in SS compared with SS-19(SHR). Depositions of collagen I and fibronectin were also greater in LV tissue of SS compared with SS-19(SHR). CONCLUSION Our findings point to a link between hypercholesterolemia and LV fibrosis in salt-sensitive hypertension of SS rats which is genetically modulated by RNO19.

Herb-Induced Liver Injury in the Berlin Case-Control Surveillance Study

Herb-induced liver injury (HILI) has recently attracted attention due to increasing reports of hepatotoxicity associated with use of phytotherapeutics. Here, we present data on HILI from the Berlin Case-Control Surveillance Study. The study was initiated in 2000 to investigate the serious toxicity of drugs including herbal medicines. Potential cases of liver injury were ascertained in more than 180 Departments of all 51 Berlin hospitals from October 2002 to December 2011. Drug or herb intake was assessed through a standardized face-to-face interview. Drug or herbal aetiology was assessed based on the updated Council for International Organizations of Medical Sciences scale. In ten of all 198 cases of hepatotoxicity included in the study, herbal aetiology was assessed as probable (once ayurvedic herb) or possible (Valeriana five times, Mentha piperita once, Pelargonium sidoides once, Hypericum perforatum once, Eucalyptus globulus once). Mean age was 56.4 ± 9.7 years, and the predominant pattern of liver injury was hepatocellular. No cases of acute liver failure or death were observed. This case series corroborates known risks for ayurvedic herbs, supports the suspected association between Valeriana use and liver injury, and indicates a hepatotoxic potential for herbs such as Pelargonium sidoides, Hypericum perforatum or Mentha piperita that were rarely associated with liver injury before. However, given that possible causality does not prove clinical significance, further studies in this field are needed.

CYP3A5 genotype-phenotype analysis in the human kidney reveals a strong site-specific expression of CYP3A5 in the proximal tubule in carriers of the CYP3A5*1 allele.

Interindividual variability in the drug-metabolizing activity of the CYP3A5 enzyme is mainly due to a single nucleotide polymorphism in CYP3A5, leading to low expression in homozygous CYP3A5*3/*3 individuals compared with CYP3A5*1 allele carriers. In the human kidney, expression of CYP3A5 has been implicated in blood pressure regulation and calcineurin inhibitor-associated nephrotoxicity. The effect of the CYP3A5*1/*3 polymorphism on the expression level and protein distribution within the human kidney is not well characterized. Therefore, we performed a genotype-phenotype analysis of CYP3A5 mRNA and protein expression in the human kidney. To this end, we analyzed sections of normal kidney tissue obtained from 93 white individuals undergoing nephrectomy by quantitative mRNA expression analysis. Qualitative protein expression analysis of CYP3A5 was performed by immunohistochemistry. Mean renal mRNA expression of carriers of the CYP3A5*1 (n = 12) allele was more than 18-fold higher than that of CYP3A5*3/*3 carriers (n = 81, p < 0.001). Immunohistochemical analysis demonstrated CYP3A5 protein in all epithelia of the nephron in kidney sections with the CYP3A5*3/*3 genotype. In carriers of the CYP3A5*1 allele, a strong increase in protein expression of CYP3A5 was detected, and this was confined to the proximal tubule. This study confirms a significant effect of the CYP3A5*1/*3 polymorphism on CYP3A5 expression in the normal human kidney and reveals a strong nephron segment-specific difference in the CYP3A5 protein expression limited to the proximal tubule.

Pharmacokinetics and safety of olmesartan medoxomil in combination with either amlodipine or atenolol compared to respective monotherapies in healthy subjects

The aim of this study was to investigate any influence on olmesartan plasma pharmacokinetics from amlodipine or atenolol. We analysed pharmacokinetics and safety of olmesartan medoxomil in combination with either amlodipine or atenolol compared to respective monotherapies in two separate studies. In one study, 18 subjects received once daily treatment for 7 days with olmesartan medoxomil 20 mg alone or with amlodipine 5 mg or amlodipine 5 mg alone. In the other study, atenolol 50 mg once daily replaced amlodipine. Concentration vs. time profiles for olmesartan monotherapy were similar to combination therapy. Mean olmesartan AUCss,τ for olmesartan alone and with amlodipine were 2439 and 2388 ng h/mL and for olmesartan alone and with atenolol were 2340 and 2247 ng h/mL. Corresponding olmesartan Css,max values were 465.7 and 439.5 ng/mL for amlodipine, and 447.4 and 423.8 ng/mL for atenolol. Median tmax values for olmesartan were 1.5 h for each group in each study. Bioequivalence was established for all pharmacokinetic parameters. Lack of significant pharmacokinetic interactions between olmesartan and amlodipine or atenolol provides a basis for combination therapy.