Association of hyperuricemia and serum uric acid lowering therapy with mortality in hemodialysis patients.

INTRODUCTION: In the general population, hyperuricemia is associated with increased morbidity and mortality. Data on this association in hemodialysis patients is controversial. Moreover, it remains elusive whether serum uric acid (SUA) lowering therapy is associated with mortality. METHODS: Retrospective analysis of 601 patients on chronic hemodialysis therapy in five outpatient centers with a maximum follow-up of 100 and a mean follow-up of 41 months. Death was defined as primary endpoint. Cumulative survival was analyzed by Kaplan-Meier analysis and Cox regressions adjusted for age. FINDINGS: Cumulative survival rates were higher for those subjects with a higher than median SUA concentration both based on mean annual and baseline measurements (p < 0.05 each). There was no survival difference anymore after adjustment for age (p > 0.05 each). Stratification for SUA lowering therapy (allopurinol/febuxostat) had no impact on cumulative survival, neither in Kaplan Meier nor in Cox regression analyses (p > 0.05 each). Furthermore, Cox regression analysis excluded an increased cardiovascular mortality in subjects with hyperuricemia. DISCUSSION: In contrast to the general population, hyperuricemia is not associated with increased mortality in patients undergoing hemodialysis. Moreover, xanthine oxidase inhibition was not associated with a survival benefit in this analysis. These data do not support the use of SUA lowering medication in hemodialysis patients with asymptomatic hyperuricemia.

Endothelin-1 Overexpression Improves Renal Function in eNOS Knockout Mice.

BACKGROUND/AIMS: To investigate the renal phenotype under conditions of an activated renal ET-1 system in the status of nitric oxide deficiency, we compared kidney function and morphology in wild-type, ET-1 transgenic (ET+/+), endothelial nitric oxide synthase knockout (eNOS-/-) and ET+/+eNOS-/- mice. METHODS: We assessed blood pressure, parameters of renal morphology, plasma cystatin C, urinary protein excretion, expression of genes associated with glomerular filtration barrier and tissue remodeling, and plasma metabolites using metabolomics. RESULTS: eNOS-/- and ET+/+eNOS-/- mice developed hypertension. Osteopontin, albumin and protein excretion were increased in eNOS-/- and restored in ET+/+eNOS-/- animals. All genetically modified mice developed renal interstitial fibrosis and glomerulosclerosis. Genes involved in tissue remodeling (serpine1, TIMP1, Col1a1, CCL2) were up-regulated in eNOS-/-, but not in ET+/+eNOS-/- mice. Plasma levels of free carnitine and acylcarnitines, amino acids, diacyl phosphatidylcholines, lysophosphatidylcholines and hexoses were descreased in eNOS-/- and were in the normal range in ET+/+eNOS-/- mice. CONCLUSION: eNOS-/- mice developed renal dysfunction, which was partially rescued by ET-1 overexpression in eNOS-/- mice. The metabolomics results suggest that ET-1 overexpression on top of eNOS knockout is associated with a functional recovery of mitochondria (rescue effect in ß-oxidation of fatty acids) and an increase in antioxidative properties (normalization of monounsaturated fatty acids levels).

Loss of insulin-induced activation of TRPM6 magnesium channels results in impaired glucose tolerance during pregnancy.

Hypomagnesemia affects insulin resistance and is a risk factor for diabetes mellitus type 2 (DM2) and gestational diabetes mellitus (GDM). Two single nucleotide polymorphisms (SNPs) in the epithelial magnesium channel TRPM6 (V(1393)I, K(1584)E) were predicted to confer susceptibility for DM2. Here, we show using patch clamp analysis and total internal reflection fluorescence microscopy, that insulin stimulates TRPM6 activity via a phosphoinositide 3-kinase and Rac1-mediated elevation of cell surface expression of TRPM6. Interestingly, insulin failed to activate the genetic variants TRPM6(V(1393)I) and TRPM6(K(1584)E), which is likely due to the inability of the insulin signaling pathway to phosphorylate TRPM6(T(1391)) and TRPM6(S(1583)). Moreover, by measuring total glycosylated hemoglobin (TGH) in 997 pregnant women as a measure of glucose control, we demonstrate that TRPM6(V(1393)I) and TRPM6(K(1584)E) are associated with higher TGH and confer a higher likelihood of developing GDM. The impaired response of TRPM6(V(1393)I) and TRPM6(K(1584)E) to insulin represents a unique molecular pathway leading to GDM where the defect is located in TRPM6.

Renin angiotensin aldosterone system and glycemia in pregnancy.

BACKGROUND: The renin-angiotensin-aldosterone system (RAAS) is involved in the pathogenesis of insulin resistance and type 2 diabetes in the general population. The RAAS is activated during pregnancy. However, it is unknown whether the RAAS contributes to glycemia in pregnant women. METHODS: Plasma renin activity (PRA) and plasma aldosterone levels were quantified at delivery in 689 Chinese mothers. An oral glucose tolerance test in fasted women was performed in the second trimester of pregnancy. The diagnosis of gestational diabetes mellitus (GDM) and impaired glucose tolerance during pregnancy were made according to the guidelines of the Chinese Society of Obstetrics. RESULTS: Plasma aldosterone was significantly higher in pregnant women with GDM as compared to those without impairment of glycemic control (normal pregnancies: 0.27 +/- 0.21 ng/mL, GDM: 0.36 +/- 0.30 ng/mL; p < 0.05). Regression analyses revealed that PRA was negatively correlated with fasting blood glucose (FBG) (R2 = 0.03, p = 0.007), whereas plasma aldosterone and aldosterone/PRA ratio were positively correlated with FBG (R2 = 0.05, p < 0.001 and R = 0.03, p = 0.007, respectively). Multivariable regression analysis models considering relevant confounding factors confirmed these findings. CONCLUSIONS: This study demonstrated that fasting blood glucose in pregnant women is inversely correlated with the PRA, whereas plasma aldosterone showed a highly significant positive correlation with fasting blood glucose during pregnancy. Moreover, plasma aldosterone is significantly higher in pregnant women with GDM as compared to those women with normal glucose tolerance during pregnancy. Although causality cannot be proven in association studies, these data may indicate that the RAAS during pregnancy contributes to the pathogenesis of insulin resistance/new onset of diabetes during pregnancy.

Low-density lipoprotein apheresis is associated with removal of SARS-CoV-2 antibodies.

BACKGROUND: Low-density lipoprotein apheresis is not specific to lipoproteins but removes immunoglobulins as well. It remains elusive, whether protective SARS-CoV-2 antibodies after vaccination from COVID-19 are eliminated as well. METHODS: A cross-sectional case-control study on 55 patients undergoing weekly lipoprotein apheresis and 21 patients with comparable comorbidities and epidemiology not undergoing apheresis. SARS-CoV-2 IgG was assessed in all patients prior to apheresis and in 38 patients both before and after apheresis. RESULTS: SARS-CoV-2 IgG concentrations before a session of lipoprotein apheresis were comparable to control patients not undergoing apheresis(1727 IU/ml, IQR 365-2500) vs. 1652 IU/ml,(IQR408.8-2500), p = 0.78). SARS-CoV-2 IgG concentrations were reduced by lipoprotein apheresis from 1656 IU/ml(IQR 540.5-2500) prior to 1305 IU/ml (IQR 449-2500) afterwards(p < 0.0001). CONCLUSION: Lipoprotein apheresis removes SARS-CoV-2 IgG. The average elimination rate was 21.2%. In the present population of patients undergoing apheresis once weekly, however, the elimination did not lead to inferior concentrations compared to patients not undergoing lipoprotein apheresis.

Birthweight and fetal glycosylated hemoglobin at birth in newborns carrying the GLUT1 XbaI gene polymorphism.

BACKGROUND: Low birthweight is an independent risk factor of glucose intolerance and type 2 diabetes in later life. Genetically determined insulin resistance and subsequently impaired glucose uptake might explain both reduced fetal growth and elevated blood glucose. The glucose transporter 1 (GLUT1) plays an important role for fetal glucose uptake as well as for maternal-fetal glucose transfer, and it has been associated with insulin resistance in adults. The present study hypothesized that the common fetal GLUT1 XbaI polymorphism might reduce fetal insulin sensitivity and/or glucose supply in utero, thus affecting fetal blood glucose and fetal growth. METHODS: A genetic association study was conducted at the obstetrics department of the Charité University Hospital, Berlin, Germany. 1191 white women were included after delivery, and all newborns were genotyped for the GLUT1 XbaI polymorphism. Total glycosylated hemoglobin was quantified, serving as a surrogate of glycemia during the last weeks of pregnancy. RESULTS: The analysis of this large population showed no significant differences in fetal glycosylated hemoglobin or birthweight for the different fetal GLUT1 XbaI genotypes. Only newborns carrying the mutated allele show the previously published inverse association between birthweight and glycosylated hemoglobin. CONCLUSIONS: The results suggest that there is no prenatal effect of the fetal GLUT1 XbaI polymorphism on fetal insulin sensitivity, intrauterine fetal glucose supply or fetal growth. However, the polymorphism seems to modulate the inverse interaction between birthweight and fetal glycemia.

Renoprotective effects of combined endothelin-converting enzyme/neutral endopeptidase inhibitor SLV338 in acute and chronic experimental renal damage.

BACKGROUND: Acute kidney injury (AKI) as well as chronic renal failure are associated with a huge mortality/morbidity. However, so far no drugs have been approved for the treatment of acute kidney failure and only a few for the treatment of chronic kidney disease (CKD). We analysed the effect of SLV338, a neutral endopeptidase (NEP)/endothelin converting enzyme (ECE)-inhibitor in animal models of acute kidney failure as well as chronic renal failure. METHODS: Acute renal failure was induced in male Wistar rats by uninephrectomy and clamping of the remaining kidney for 55 minutes. SLV338 (total dose: 4.9 mg/kg) or vehicle was continuously infused for 2 hours (starting 20 minutes prior to clamping). Sham operated animals served as controls. Plasma creatinine was measured at baseline and day 2 and 8 after renal ischemia-reperfusion. Hypertensive renal damage was induced in male Sprague Dawley rats by nitric oxide deficiency using L-NAME (50 mg/kg per day, added to drinking water for 4 weeks). One group was treated over the same time period with SLV338 (30 mg/kg per day, mixed with food). Systolic blood pressure was monitored weekly. At study end, urine and blood samples were collected and kidneys were harvested. RESULTS: Acute renal ischemia-reperfusion caused a 5-fold plasma creatinine elevation (day 2), which was significantly attenuated by more than 50% in animals treated with SLV338 (p < 0.05). Renal failure was accompanied by a 67% mortality in vehicle-treated rats, but only 20% after SLV338 treatment (p = 0.03 compared to sham controls). Chronic L-NAME administration caused hypertension, urinary albumin excretion, glomerulosclerosis, renal arterial remodelling, and renal interstitial fibrosis. Treatment with SLV338 did not significantly affect blood pressure, but abolished renal tissue damage (interstitial fibrosis, glomerulosclerosis, renal arterial remodelling (p < 0.05 versus L-NAME group in each case). CONCLUSIONS: The dual ECE/NEP inhibitor SLV338 preserves kidney function and reduces mortality in severe acute ischemic renal failure. Moreover, combined ECE/NEP inhibition prevents hypertensive renal tissue damage in a blood pressure independent manner in L-NAME-treated rats.

Interaction of maternal peroxisome proliferator-activated receptor gamma2 Pro12Ala polymorphism with fetal sex affects maternal glycemic control during pregnancy.

It was suggested that fetal sex may substantially affect maternal glycemic control during pregnancy in genetically susceptible mothers. The peroxisome proliferator-activated receptor gamma2 (PPARgamma2) Pro12Ala polymorphism is known to affect glycemic control and may act in a sex-specific manner. This polymorphism is thus an attractive candidate to test this hypothesis using a second independent functionally relevant polymorphism. We analyzed the impact of fetal sex on maternal glycemic control during pregnancy in relation to the maternal PPARgamma2 Pro12Ala polymorphism. Two-thousand fourteen Caucasian women without preexisting diabetes and preexisting hypertension with singleton pregnancies delivering consecutively at the Charité obstetrics department were genotyped. Glycemic control was analyzed by measuring total glycated hemoglobin at birth. Correction for confounding factors and multiple testing was considered in the analysis. The maternal PPARgamma2 Pro12Ala polymorphism without consideration of fetal sex had no effect on blood pressure, new onset of proteinuria and total glycated hemoglobin at delivery. Mothers carrying both G alleles (GG genotype) delivering a girl had a higher (P = 0.015) total glycated hemoglobin (6.81 or - 0.50%) versus mothers carrying the same alleles but delivering boys (5.85 + or - 0.58%). Comparing mothers with the GG genotype delivering girls with mothers with CC or CG genotypes also delivering girls (6.32 + or - 0.72%) revealed a significantly higher maternal total glycated hemoglobin at delivery in the former group (P < 0.009). Fetal sex/sex chromosomes may substantially affect maternal glycemic control in mothers who are carriers of the GG alleles of the PPARgamma2 Pro12Ala polymorphism.

Maternal and fetal PROGINS progesterone receptor polymorphism reduces the risk for transient tachypnea of the newborn.

BACKGROUND: Transient tachypnea of the newborn (TTN) is the most common perinatal respiratory disorder. It was suggested that the pathogenesis of TTN might involve altered activity of female sex hormones. This study analyzed whether the PROGINS progesterone receptor polymorphism, which is less responsive to progesterone, is associated with TTN. METHODS: A cohort of 2352 infants born to Caucasian women at the Obstetrics Department of the Charite was investigated prospectively. The collected information included the occurrence of respiratory disorders, birth weight, gestational age at delivery, mode of delivery, and maternal morbidity. Mothers and newborns were genotyped for the PROGINS progesterone receptor polymorphism. Statistical analyses considered correction for confounding factors. RESULTS: The presence of the mutated T2-allele either in mothers or in infants was associated with a reduction of the incidence of TTN in a gene dose-dependent manner (mothers T1/T1: 6.6%, T1/T2: 4.3% T2/T2: 2.3%, p < 0.01; infants T1/T1: 6.5%, T1/T2: 4.7%, T2/T2: 0.0%, p = 0.02 in a multivariable regression model). The total number of mutated T2-alleles present in a mother/child pair was associated with a reduction of TTN (4 T2-alleles: 6.4%, n=95; 3: 5.9%, n=30; 2: 3.1%, n=9; 1: 1.4%, n=1; 0:0%, n=0; p < 0.01 in a multivariable regression model). CONCLUSIONS: Both the maternal and fetal mutated alleles of the PROGINS progesterone receptor polymorphism seem to protect from TTN. The same phenotype occurs regardless of whether the mutation is localized in the mother or in the infant. Fetal as well as maternal T2-alleles synergistically reduce the risk for TTN in a gene dose-dependent manner.

Gender-dependent impact of risk factors for cardiovascular and non-cardiovascular mortality in end-stage renal disease patients on haemodialysis.

We investigated whether mortality risk factors are gender dependent in haemodialysis patients. Patients (n = 230; 118 women, 112 men) on haemodialysis were followed for 52 months to assess the incidence of death due to cardiovascular or non-cardiovascular causes. Survival was compared by Cox regression analysis using age, diabetes, pre-existing coronary disease, troponin T and C-reactive protein as covariates. In total, 120 participants (52.2%) died within the 52 months of follow-up: 57 patients died of cardiovascular disease, 35 patients died of infectious diseases. Cox regression revealed that age, pre-existing coronary heart disease and troponin T were independent all-cause mortality risk factors for both sexes. Analyzing men and women separately revealed that diabetes and C-reactive protein seemed to be a stronger risk factors for all-cause mortality in women. Cardiovascular mortality was predicted by troponin T in women (relative risk = 5.16, 95% CI: 1.67-15.88; p = 0.004), but not in men (relative risk = 1.69; 95% CI: 0.72-3.96; p = 0.23). Our study showed for the first time that the impact of risk factors in predicting death due to cardiovascular disease is clearly gender dependent.

Lack of iNOS impairs endothelial function in endothelin-1 transgenic mice.

BACKGROUND: Endothelin-1 (ET-1) is one of the most potent biologic vasoconstrictors. Nevertheless, transgenic mice overexpressing ET-1 exhibit normal blood pressure. We hypothesized that in states of ET-1 overproduction, the lack of counterregulatory mediators such as nitric oxide (NO), produced by the inducible NO synthase (iNOS), may critically impair endothelial function and may result in blood pressure elevation. METHODS: We generated crossbred animals of ET transgenic mice (ET+/+) and iNOS knockout mice (iNOS-/-) and evaluated blood pressure and endothelial function in these animals. Endothelium-dependent and -independent vascular function was assessed as relaxation/contraction of isolated preconstricted aortic rings to acetylcholine, sodium nitroprusside, and ET-1, alone or in the presence of BQ123 or BQ788. RESULTS: Systolic blood pressure was similar in ET+/+, iNOS-/- and wild-type mice, but was significantly elevated in ET+/+ iNOS-/- crossbred animals versus ET+/+ mice. Maximum endothelium-dependent relaxation was enhanced in ET+/+ mice (95 +/- 5 vs. 78 +/- 5% of preconstriction in wild-type littermates; p < 0.05). Additional knockout of iNOS led to a significant decrease of endothelium-dependent relaxation in combined ET+/+ iNOS-/- animals (75 +/- 6%; p < 0.05 vs. ET+/+ mice). Endothelium-independent relaxation was comparable among all groups. Maximum vascular contraction to ET-1 was reduced in ET+/+ mice (33 +/- 4%), iNOS-/- mice (38 +/- 5%) and ET+/+ iNOS-/- mice (44 +/- 4%) to a similar extent as compared with wild-type littermates (66 +/- 4%; p < 0.05). CONCLUSIONS: Our data show for the first time that in transgenic mice overexpressing human ET-1, additional knockout of iNOS results in impaired endothelium-dependent vasodilatation thus contributing to elevated blood pressure in ET+/+ iNOS-/- animals.

Low birth weight, a risk factor for cardiovascular diseases in later life, is already associated with elevated fetal glycosylated hemoglobin at birth.

BACKGROUND: It remains unclear whether the association between low birth weight and insulin resistance in adulthood has its origin in utero or whether it develops later in life depending on predisposition and exogenous factors. METHODS AND RESULTS: Total glycosylated hemoglobin (TGH) was quantified at delivery in 1295 mother/child pairs serving as a surrogate of maternal and fetal glycemia. Multivariable regression analysis considering gestational age at delivery, the child's sex, maternal body mass index, and smoking during pregnancy revealed that an increase in TGH by 1% in the child was significantly associated with a mean birth weight reduction of 135 g (P<0.0001), whereas the same increase in the mother was associated with a mean birth weight increase of 88 g (P<0.0001). The ratio of fetal/maternal TGH suggests that lighter newborns have a higher percentage of TGH than would be expected from maternal TGH. CONCLUSIONS: The study demonstrates for the first time in a large population that there is an inverse association between TGH of a newborn and its birth weight. This might be due to increased insulin resistance in newborns with lower birth weight. Our data suggest that the pathophysiological mechanisms linking prenatal growth and postnatal sensitivity to insulin are present as early as before birth.

Impact of maternal angiotensinogen M235T polymorphism and angiotensin-converting enzyme insertion/deletion polymorphism on blood pressure, protein excretion and fetal outcome in pregnancy.

OBJECTIVE: To test the hypothesis that genetically determined alterations of the renin-angiotensin system are associated with hypertensive disorders in pregnancy. METHODS: A genetic association study was conducted at the obstetrics department of the Charité university hospital, Berlin, Germany. A total of 1068 Caucasian women were consecutively included after delivery and genotyped for the angiotensinogen M235T polymorphism and the angiotensin-converting enzyme (ACE) insertion/deletion polymorphism. RESULTS: Women homozygous for the angiotensinogen T allele have significantly elevated mean systolic and diastolic blood pressures in the third trimester (118.4 +/- 1.1/71.5 +/- 0.7 versus 116.9 +/- 0.3/70.4 +/- 0.2 mmHg, n = 128 versus 940; P < 0.05). This finding is especially pronounced in the subgroup of primigravid women. The ACE polymorphism is not associated with blood pressure during pregnancy. None of the polymorphisms is associated with urinary protein excretion or oedema during pregnancy. Maternal polymorphisms do not influence fetal growth and birth weight. There is, however, an interesting trend towards an increased incidence of circulatory system malformations in newborns carrying alleles that are known to be associated with decreased intrinsic renin-angiotensin system activity. CONCLUSION: We demonstrate for the first time in a large Caucasian population that a common maternal polymorphism of the angiotensinogen gene is related to a blood pressure increase during pregnancy. The angiotensinogen M235T polymorphism might contribute to the multifactorial pathogenesis of gestational hypertension and pre-eclampsia.

Impact of genetic variation of tumor necrosis factor-alpha on gestational hypertension.

BACKGROUND: The mechanisms responsible for the pathogeneses of gestational hypertension and preeclampsia are unclear. Tumor necrosis factor-alpha (TNF-alpha) is a pro-inflammatory Th(1)-type cytokine. TNFA gene is located in the human leukocyte antigen (HLA) class III region of the major histocompatibility complex (MHC) on chromosome 6. The high TNF-alpha mRNA expression may be associated with the TNF2 (A) allele, which is the polymorphism of TNF-alpha at position -308 in promoter region. This study assessed whether the TNF2 (A) allele at position -308 plays a role in the alteration of blood pressure (BP) and urinary protein excretion during pregnancy. METHODS: The original prospective cohort study comprised 1623 pregnant women from January 2000 to October 2001. The G/A polymorphism was done by restriction fragment length polymorphism (RFLP) analysis with Nco I enzyme. RESULTS: The distributions of the G/A polymorphism of TNF-alpha in the promoter region at position -308 were wild-type 72.4% and variant 27.6%, respectively. The frequency of TNF2 (A) allele was approximately 0.15 for Caucasian pregnant women in the study. It was not significantly different in the distributions of genotypes and G/A allele frequencies among the three groups of pregnant women with gestational hypertension, preexisting hypertension and normal blood pressure (P > 0.05). The maternal blood pressure in the third trimester was significantly higher in the group of women possessing the TNF2 (A) allele compared to homozygous for the TNF1 (G) allele (systolic BP, P < 0.01 and diastolic BP, P < 0.05). The elevated blood pressure in the TNF2 (A) group was accompanied by higher urinary protein excretion in the third trimester (P < 0.05). The blood pressure and urinary protein excretion did not change apparently between the two groups in the first and second trimesters (P > 0.05). CONCLUSIONS: Maternal TNF2 (A) allele of TNF-alpha promoter region at position -308 could play a role in the alteration of blood pressures and/or enhancement of urinary protein excretion during pregnancy, and might play an important role in the development of both gestational hypertension and preeclampsia.

Maternal eNOS deficiency determines a fatty liver phenotype of the offspring in a sex dependent manner.

Maternal environmental factors can impact on the phenotype of the offspring via the induction of epigenetic adaptive mechanisms. The advanced fetal programming hypothesis proposes that maternal genetic variants may influence the offspring's phenotype indirectly via epigenetic modification, despite the absence of a primary genetic defect. To test this hypothesis, heterozygous female eNOS knockout mice and wild type mice were bred with male wild type mice. We then assessed the impact of maternal eNOS deficiency on the liver phenotype of wild type offspring. Birth weight of male wild type offspring born to female heterozygous eNOS knockout mice was reduced compared to offspring of wild type mice. Moreover, the offspring displayed a sex specific liver phenotype, with an increased liver weight, due to steatosis. This was accompanied by sex specific differences in expression and DNA methylation of distinct genes. Liver global DNA methylation was significantly enhanced in both male and female offspring. Also, hepatic parameters of carbohydrate metabolism were reduced in male and female offspring. In addition, male mice displayed reductions in various amino acids in the liver. Maternal genetic alterations, such as partial deletion of the eNOS gene, can affect liver metabolism of wild type offspring without transmission of the intrinsic defect. This occurs in a sex specific way, with more detrimental effects in females. This finding demonstrates that a maternal genetic defect can epigenetically alter the phenotype of the offspring, without inheritance of the defect itself. Importantly, these acquired epigenetic phenotypic changes can persist into adulthood.

Endothelin B receptor-deficient mice develop endothelial dysfunction independently of salt loading.

BACKGROUND: Rodents without a functional endothelin B (ETB) receptor develop salt-sensitive hypertension. The underlying mechanisms, however, are so far unknown. The ETB receptor is involved in endothelial function by modulating the activity of the endothelial nitric oxide synthesis as well as contributing to the control of endothelial prostacyclin synthesis. In the present study, we analysed whether salt alters endothelial function in rescued ETB receptor-deficient mice. We used mice with a rescue of the lethal phenotype of an ETB knockout. These mice were generated by crossbreeding ETB mice with dopamine-hydroxylase ETB transgenic mice. METHODS: Adult rescued ETB-deficient mice were kept in parallel with wild-type control animals for 15 days on standard (0.2% NaCl) or salt-enriched (4% NaCl) chow, respectively. Systolic blood pressure was measured by the tail cuff method and endothelium-dependent and endothelium-independent vascular function was assessed in isolated aortic rings under isometric conditions. RESULTS: Systolic blood pressure increased on salt-enriched chow in ETB receptor-deficient mice (166 +/- 12 mmHg), but neither in wild-type mice on high-salt diet (128 +/- 11 mmHg; P < 0.05) nor in ETB receptor-deficient mice on standard chow. The heart rate was similar in all groups at any point of time. Endothelium-dependent relaxation was impaired in ETB receptor-deficient mice (74 +/- 3 versus 96 +/- 5% of preconstriction for wild-type mice; P < 0.05) and was not significantly affected by a salt-enriched diet. Endothelium-independent relaxation was similar among all groups. Contractions to endothelin-1 were not significantly influenced by preincubation with the ETB receptor antagonist BQ-788, but were completely blunted by preincubation with the ETA receptor antagonist BQ-123 in all animals. CONCLUSION: Rescued ETB receptor-deficient mice develop salt-sensitive hypertension. Nevertheless, in this animal model of ETB receptor deficiency, endothelial function is impaired independent of salt-enriched diet or hypertension. This indicates that, in this model, salt-induced hypertension is not mediated by endothelial dysfunction.

Impact of genes related to immune tolerance and inflammation (tumour necrosis factor-alpha, interleukin-6) on blood pressure, protein excretion and oedema in pregnancy.

OBJECTIVE: To test the hypothesis that genetically determined alterations of maternal immune tolerance to a foetal semi-allograft are important for the pathogenesis of hypertensive disorders in pregnancy. DESIGN: A genetic association study was performed to analyse the impact of genetic polymorphisms known to be involved in immune tolerance on markers of pre-eclampsia. SETTING: The study was conducted at the Obstetrics Department of the Charité University Hospital, Berlin, Germany. PARTICIPANTS: A total of 1480 Caucasian women were consecutively included after delivery and genotyped for two polymorphisms: tumour necrosis factor-alpha -308G>A and interleukin-6 -174G>C. MAIN OUTCOME MEASURES: Systolic and diastolic blood pressures, urinary protein excretion and oedema during pregnancy. RESULTS: Only women carrying at least one mutant allele of both polymorphisms (tumour necrosis factor-alpha A and interleukin-6 C) have a significantly elevated mean systolic blood pressure and diastolic blood pressure at the end of pregnancy. The tumour necrosis factor-alpha A allele on its own is significantly associated with urinary protein excretion in the last trimenon, and the interleukin-6 C allele is independently and significantly associated with new-onset oedema. CONCLUSIONS: We demonstrate in a large population that common maternal polymorphisms of genes related to immune tolerance and inflammation are associated with blood pressure regulation, urinary protein excretion and oedema during pregnancy. The analysed polymorphisms seem to contribute to the multifactorial pathogenesis of gestational hypertension and pre-eclampsia. The findings support the hypothesis that genetically determined factors of maternal immune tolerance play a role in the pathogenesis of hypertensive disorders in pregnancy.

The endothelin system in Morris hepatoma-7777: an endothelin receptor antagonist inhibits growth in vitro and in vivo.

1. Plasma concentrations of endothelin are increased in patients with hepatocellular cancer as well as in patients with liver metastasis. However, the impact of these findings remains uncertain. 2. We thus analyzed the endothelin system in a rat hepatoma model (Morris hepatoma 7777) in vitro and in vivo. 3. Our study revealed that tissue concentrations of endothelin-1 (ET-1) and big-ET-1, the precursor of ET-1, were significantly elevated in Morris hepatoma 7777 as compared to normal liver. The ETA receptor density was significantly elevated, whereas the density of the ETB receptor was decreased in Morris hepatoma 7777. 4. We could also demonstrate that hepatoma cells secrete ET-1. 5. Exogenously added ET-1 enhances hepatoma cell growth in a dose-dependent manner. Endothelin receptor antagonists (ETA and combined ETA/ETB receptor antagonists) inhibit tumor cell growth in vitro. Since the combined ETA/ETB receptor antagonist was more effective in vitro, we used this compound also for in vivo studies and could demonstrate that a combined ETA/ETB receptor antagonist is able to reduce hepatoma growth in vivo. 6. In conclusion, the endothelin system is activated in Morris hepatoma 7777 and contributes to hepatoma growth. Since endothelin receptor antagonists are well-tolerated upcoming clinically used drugs without major side effects, our data might provide a new pharmacological approach to reduce hepatoma growth in vivo.

The novel DPP-4 inhibitors linagliptin and BI 14361 reduce infarct size after myocardial ischemia/reperfusion in rats.

BACKGROUND: Dipeptidylpeptidase-4 inhibition is reported to have beneficial effects on myocardial ischemia. Mechanisms might include a reduced degradation of stromal cell-derived factor-1 alpha with subsequent increased recruitment of circulating stem cells and/or incretin receptor-dependent pathways. This study evaluated the novel xanthine-based dipeptidylpeptidase-4 inhibitors linagliptin (BI 1356) and BI 14361 in cardiac ischemia. METHODS: Male Wistar rats were pretreated with linagliptin or BI 14361 and subjected to ligation of the left anterior descending coronary artery for 30 min. RESULTS: Dipeptidylpeptidase-4 inhibition significantly reduced the infarct size after 7 days (-27.7%, p<0.05) and 8 weeks (-18.0%, p<0.05). There was a significantly improved maximum rate of left ventricular pressure decline (dP/dt min) in linagliptin-treated animals 8 weeks after ischemia/reperfusion. Apart from that, treatment did not improve cardiac function as determined by echocardiography and cardiac catheterization. Immunohistological staining revealed an increased number of cells positive for stromal cell-derived factor-1 alpha, CXCR-4 and CD34 within and around the infarcted area of BI 14361-treated animals. CONCLUSIONS: Linagliptin and BI 14361 are able to reduce infarct size after myocardial ischemia. The immunohistological findings support the hypothesis that dipeptidylpeptidase-4 inhibition via reduced cleavage of stromal cell-derived factor-1 alpha might lead to an enhanced recruitment of CXCR-4+ circulating progenitor cells.