Classification of chronic kidney disease by estimated glomerular filtration rate.

BACKGROUND: Serum creatinine concentration alone as a marker of kidney function is inadequate. Thus several equations for estimating glomerular filtration rate (eGFR) have been proposed within the last years. PATIENTS AND METHODS: In our study we compared three frequently used equations, the abbreviated modification of diet in renal disease (MDRD) formula, the extended MDRD formula and the recently proposed Mayo clinic equation in a large patient cohort. RESULTS: A total of 244 507 patients attending the Vienna General Hospital were evaluated for their kidney function and three equations for eGFR were compared. The median age of the patients was 51 years (ranging from 18.0 to 102.6 years) with 44.3% males (n = 108 527). We observed a significant increase of patients with eGFR classes four and five (according to Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines) with advanced age. Whereas approximately 1% of patients < 30 years presented with eGFR classes four and five (defined as eGFR < 30 mL min(-1) 1.73 m(-2)), this prevalence increased up to approximately 12% in patients at the age of 80 years or older. All three equations showed comparable results for eGFR classes four and five. The proportion of patients with mild to moderate impairment of kidney function is higher using both MDRD equations. CONCLUSIONS: The MDRD equations (particularly the abbreviated MDRD formula) result in considerably higher rates of eGFR classes two and three compared to the Mayo Clinic equation, while all three were comparable in classes four and five. This should be considered when eGFR is used in the diagnosis of chronic kidney disease.

Interaction between plasminogen activator inhibitor type 1 (PAI-1) bound to fibrin and either tissue-type plasminogen activator (t-PA) or urokinase-type plasminogen activator (u-PA). Binding of t-PA/PAI-1 complexes to fibrin mediated by both the finger and the kringle-2 domain of t-PA.

Plasminogen activation is catalyzed both by tissue-type-(t-PA) and by urokinase-type plasminogen activator (u-PA). This reaction is controlled by plasminogen activator inhibitor type 1 (PAI-1) that is either present in plasma or bound to fibrin, present in a thrombus. We studied the mechanism of in vitro inhibition of both t-PA and u-PA activity by PAI-1 bound to fibrin. It is shown that activation of latent PAI-1 unmasks a specific fibrin-binding site that is distinct from its reactive site. This reactive site of activated PAI-1 bound to fibrin is fully exposed to form complexes with t-PA and u-PA, that are unable to activate plasminogen. Upon complex formation with either one of the plasminogen activators, PAI-1 apparently undergoes a conformational change and loses its affinity for fibrin. Consequently, complexes of u-PA and PAI-1 dissociate from the fibrin matrix and are encountered in the fluid phase. In contrast, t-PA/PAI-1 complexes remain bound to fibrin. By employing recombinant t-PA deletion-mutant proteins, that precisely lack domains involved in fibrin binding, we demonstrate that binding of t-PA/PAI-1 complexes is mediated by both the "finger" (F) and the "kringle-2" (K2) domain of t-PA. A model is proposed that explains inhibition of the fibrinolytic process, at the level of plasminogen activation by t-PA, directed by PAI-1 bound to fibrin. An implication of the proposed model is that t-PA/PAI-1 complexes and free t-PA compete for the same binding sites on fibrin.

Association of low-grade inflammation with nephropathy in type 2 diabetic patients: role of elevated CRP-levels and 2 different gene-polymorphisms of proinflammatory cytokines.

BACKGROUND: Chronic inflammatory processes are thought to play a key role in the development of micro- and macrovascular complications in type 2 diabetes mellitus. An association between low -grade inflammation and type 2 diabetes has been described in some studies. We assayed the association of two frequent polymorphisms in proinflammatory cytokines: the interleukin 6 G(-174)C promoter polymorphism [IL-6G(-174)C], the exon 2 interleukin receptor antagonist insertion deletion polymorphism [IL1RA]) and serum CRP levels with the prevalence of diabetic nephropathy in patients suffering from type 2 diabetes mellitus. SUBJECTS AND METHODS: A total of 141 patients with type 2 diabetes mellitus, with and without diabetic nephropathy was genotyped for the above mentioned polymorphisms: 66 with normoalbuminuria, 31 with microalbuminuria and 44 with macroalbuminuria. CRP levels were analysed by a high sensitivity - immunnephelometric assay. RESULTS: While a significant association be-tween macroalbuminuria and CRP could be observed (p<0,015), no associations were found between IL-6G(-174)C or IL1RA genotype and any stage of nephropathy. CRP-levels were similar in the 3 different IL-6G(-174)C genotypes as well as in the 2 IL1RA genotypes. CONCLUSIONS: In type 2 diabetic subjects elevated CRP levels are associated with an increased prevalence of albuminuria. The two investigated proinflammatory polymorphisms do not seem to contribute to initiation of nephropathy in type 2 diabetic patients but we cannot exclude effects of these polymorphisms on course of nephropathy.

Pronounced insulin resistance and inadequate beta-cell secretion characterize lean gestational diabetes during and after pregnancy.

OBJECTIVE: To evaluate beta-cell secretion and glucose metabolism in lean subjects with gestational diabetes mellitus (GDM) compared with that in subjects with normal pregnancy and obesity. RESEARCH DESIGN AND METHODS: Insulin secretion, insulin sensitivity (S1), and hepatic insulin extraction were assessed in pregnant women with GDM before and after delivery and in those with normal glucose tolerance (NGT) in comparison to healthy nonpregnant lean and obese women. Kinetic analysis of glucose, insulin, and C-peptide plasma concentrations during oral and intravenous glucose tolerance tests was performed by mathematical modeling. RESULTS: S1 was blunted in pregnant women with GDM by 84% and in those with NGT by 66% compared with lean nonpregnant women (P < 0.005 vs. healthy nonpregnant lean control subjects; P < 0.05, GDM vs. pregnant women with NGT), whereas glucose effectiveness was decreased by 33% in both pregnant groups (P < 0.05 vs. healthy nonpregnant lean control subjects). Insulin secretion was 30% higher (P < 0.05) in subjects with GDM than in pregnant women with NGT or in nonpregnant lean women, but decreased (P < 0.005) when compared with obese women with a comparable degree of insulin resistance. Fractional hepatic insulin extraction was similar in both pregnant groups, being lower (P < 0.0001) by 30% versus nonpregnant females. beta-cell sensitivity to glucose for insulin release was decreased in subjects with GDM versus pregnant women with NGT as well as nonpregnant women by 40-50% (P < 0.01). Twelve weeks after delivery, GDM returned to normal glucose tolerance, but S1 remained 50% lower than that in lean nonpregnant women, while beta-cell sensitivity to glucose did not change (P < 0.01 vs. healthy nonpregnant lean control subjects). CONCLUSIONS: Pregnancy is characterized by insulin resistance, diminished hepatic insulin extraction, and glucose effectiveness. Lean subjects with GDM are additionally characterized by having more pronounced insulin resistance and inadequate insulin secretion, which persist after delivery. Compared with other insulin-resistant prediabetic states like impaired glucose tolerance (IGT), defective insulin secretion seems to be a predominant defect in lean GDM subjects, indicating that it might represent a specific prediabetic condition.

Sex differences in HAART-associated dyslipidaemia.

OBJECTIVES: Because female sex protects against dyslipidaemia and atherosclerosis in normal subjects, we aimed to reveal potential sex differences in metabolic side-effects of a newly initiated highly active antiretroviral therapy (HAART) regimen, and to relate these changes to endothelial cell activation as measured by levels of circulating E-selectin (cE-selectin). DESIGN: Prospective longitudinal cohort study. SETTING: Tertiary care centre at a University Hospital. METHODS: HIV-seropositive male (n = 27) and female patients (n = 13) with a plasma viral load of > or = 10 000 copies/ml and 35 healthy controls were enrolled in the study. All participants were weight stable, free of acute opportunistic infections, and had not taken any protease inhibitors before. Serum levels of lipids, insulin, leptin, and cE-selectin were measured before initiation of HAART, and at 3 and 6 months thereafter. RESULTS: HAART increased serum levels of triglycerides, leptin, and low-density lipoprotein (LDL) cholesterol; these effects were more distinct in women. Fasting insulin levels and the LDL : high density lipoprotein (HDL) ratio increased only in female HIV-infected patients (P < 0.02 versus men). In contrast, endothelial activation, as measured by cE-selectin, decreased more in men (P < 0.02) than in women. As a consequence, women had higher triglycerides and leptin levels after therapy than did men, and the LDL : HDL ratio and cE-selectin levels, which were initially higher in men, were no longer different between the sexes. CONCLUSIONS: Metabolic adverse effects during HAART are more pronounced in women than in men. Hence, female HIV-infected patients seem to loose part of their natural protection from atherosclerosis during antiretroviral therapy.

Persistent elevation and metabolic dependence of circulating E-selectin after delivery in women with gestational diabetes mellitus.

The increased risk of premature atherosclerosis in noninsulin-dependent diabetes mellitus (NIDDM) might be related in part to augmented expression of endothelial adhesion molecules (AMs). So far it is, however, unknown whether increased circulating (c) AMs in NIDDM are only a consequence of this disease or also involved in its sequelae. To determine the presence of cAMs in a population at increased risk for subsequent development of NIDDM, we analyzed fasting and postprandial [oral glucose tolerance test (OGTT): 100 g] serum concentrations of circulating E-selectin, vascular cell adhesion molecule-1 (cVCAM-1), and intercellular adhesion molecule-1 (cICAM-1) in pregnant women with either gestational diabetes (GDM) or normal glucose tolerance (NT) before and after delivery vs. nonpregnant healthy women (C). During pregnancy cE-selectin and cVCAM-1 were elevated in both GDM and NT vs. nonpregnant females (P < 0.01 vs. C). Following delivery, all GDM females regained normal glucose tolerance according to OGTT criteria, but showed slightly higher postprandial [area under the curve (AUC)180 min] glycemia and HbA1c values than nonpregnant healthy women (P < 0.05), indicating persisting subtle abnormalities in carbohydrate metabolism. cE-selectin and cVCAM-1 remained increased in GDM (P < 0.01 vs.C) after delivery, but fell to normal in NT (P < 0.05 before vs. after delivery). Furthermore, a correlation was seen in GDM females between cE-selectin and HbA1c (P < 0.005), fasting glucose (P < 0.01), and insulin (P < 0.05) as well as postprandial (AUC180 min) glucose and insulin concentrations (P < 0.05) during OGTTs, both before and after delivery. ICAM-1, however, did not differ significantly between groups. In summary, GDM is characterized by persistently raised levels of cE-selectin and cVCAM-1 12 weeks after delivery. Whether these persistent elevations of cE-selectin and cVCAM-1 reflect early vascular injury or represent a risk factor for atherosclerosis in women at increased risk for NIDDM remains to be determined.

Elevated concentrations of circulating adhesion molecules and their association with microvascular complications in insulin-dependent diabetes mellitus.

To better understand potential associations of circulating adhesion molecules (cAMs) with diabetic microangiopathy, circulating serum concentrations of intercellular adhesion molecule-1 (cICAM-1), vascular cell adhesion molecule-1 (cVCAM-1), and endothelial leukocyte adhesion molecule-1 (cELAM-1) were determined in patients with insulin-dependent diabetes mellitus (IDDM) (n = 70) presenting with varying degree of metabolic control and status of diabetic late complications, and were compared with age-matched healthy subjects (n = 70) in a cross-sectional study. Concentrations of cICAM-1 and cVCAM-1 were elevated in IDDM vs. age-matched controls (cICAM-1: 276 +/- 71 vs. 212 +/- 57 ng/mL; P < 0.0001; cVCAM-1: 781 +/- 245 vs. 615 +/- 151 ng/mL; P < 0.0001), whereas cELAM-1 did not differ between the groups (cELAM-1: 50 +/- 25 vs. 46 +/- 23 ng/mL, P = 0.31). The levels of cVCAM-1 were more markedly elevated in IDDM patients with diabetic retinopathy (n = 32) than in those without (n = 38) (cVCAM-1: 848 +/- 281 vs. 724 +/- 197 ng/mL, P < 0.05), as well as in patients with micro- or macroalbuminuria (n = 10) vs. those without (n = 60) (cVCAM-1: 947 +/- 256 ng/mL vs. 753 +/- 234 ng/mL, P < 0.05), whereas no difference in cICAM-1 and cELAM-1 was apparent regarding the clinical status of diabetic microangiopathy. No correlations were found between hemoglobin A1e and cAMs in the individual subgroups of patients and healthy subjects. Interestingly, however, low density lipoprotein cholesterol correlated with cVCAM-1 (r = 0.38, P = 0.03) in IDDM patients with diabetic microangiopathy (n = 33), but not in healthy controls or patients without microangiopathy (n = 37). Analyzing the pooled data of diabetic patients and healthy subjects (n = 140), concentrations of cICAM-1 were markedly related to cVCAM-1 (r = 0.45, P < 0.0001) and cELAM-1 (r = 0.31, P < 0.0002), whereas cVCAM-1 was related less to cELAM-1 (r = 0.19, P = 0.03), respectively. We conclude that, irrespective of actual metabolic control, serum concentrations of cICAM-1 and cVCAM-1 but not cELAM-1 are elevated in patients with IDDM, reflecting ongoing endothelial cell stimulation and leukocyte activation. More specifically, more marked elevation of cVCAM-1 may even hint at clinically manifest diabetic microangiopathy.

Effects of hyperinsulinemia on plasma levels of circulating adhesion molecules.

Plasma levels of circulating intercellular adhesion molecule-1 (cICAM-1), a potential cardiovascular risk factor, are increased in diabetics. Among other factors, hyperinsulinemia has been proposed to enhance its release into the circulation. Thus, we directly examined the effects of insulin infusion on plasma levels of circulating adhesion molecules, and two other endothelial markers, i.e. von Willebrand factor (vWF) and soluble thrombomodulin (sTM). The study design was balanced, randomized, placebo-controlled, double blind, and cross-over. Twelve healthy male subjects received, on separate study days, a euglycemic hyperinsulinemic clamp (3 mU/kg x min) or placebo over 6 h. Plasma levels of cICAM-1, vascular cell adhesion molecule-1, circulating E-selectin, and sTM were measured by enzyme immunoassay; vWF-Ag was measured using a STA clot analyzer. Plasma levels of these adhesion molecules and endothelial cell activation markers were not affected despite a 30-fold increase in insulin levels. Hyperinsulinemia has no adverse effect on circulating ICAM-1, vascular cell adhesion molecule-1, E-selectin, vWF, or sTM and therefore does not directly induce endothelial activation.

Effects of estradiol on circulating P-selectin.

The membrane protein P-selectin tethers leukocytes to endothelial cells (EC) and on activated platelets, and may play a role in atherosclerosis. Lower plasma levels of a soluble (c) P-selectin have recently been observed in premenopausal women compared to those in men. Given the antiatherogenic-cardioprotective effect of 17 beta-estradiol (E2), we hypothesized that E2 may down-regulate the expression of P-selectin and subsequently decrease cP-selectin levels. The effects of E2 on levels of plasma cP-selectin were evaluated during the menstrual cycle in healthy women (n = 18) and by measuring the effect of a single im injection of 10 mg E2 valerate (n = 9) or placebo (n = 10) on cP-selectin levels in healthy male volunteers. In women, the cyclic increase in serum E2 concentrations was accompanied by a decrease in cP-selectin levels from 110 ng/mL [95% confidence interval (CI), 100-137 ng/mL] in the follicular phase. The decrease reached a maximum of 13% (95% CI, 2-19%, P = 0.014) in the luteal phase. In men, cP-selectin decreased from a median of 139 ng/mL (95% CI, 113-165) to 125 ng/mL (95% CI, 97-152; P = 0.038) 4 days after E2 injection. The median baseline value of cP-selectin in the 19 male volunteers was 133 ng/mL (95% CI, 115-143 ng/mL) and was approximately 30% higher than those in the female volunteers during the midcycle (P = 0.024) and luteal (P = 0.012) phases, but was not different from that during the follicular phase. In sum, our study suggests that E2 lowers cP-selectin levels. An E2-induced decrease in cP-selectin reflects either decreased activation or damage of platelets and/or endothelial cells in vivo. Thus, our study may point to an additional mechanism for the residual antiatherogenic-cardioprotective effect of E2 that cannot be explained by its lipid-lowering effects.

Effects of 17 beta-estradiol on circulating adhesion molecules.

The effects of 17 beta-estradiol (E2) on the serum levels of the circulating endothelial-leukocyte, intercellular, and vascular adhesion molecules [ELAM-1, ICAM-1 (CD54), and VCAM-1] were evaluated in healthy male volunteers after single im injection of 10 mg E2 valerate. In addition, a time course of the effects of E2 on circulating adhesion molecules (AMs), cortisol serum levels, differential blood counts, and surface expression of the lymphocyte function-associated antigen-1 (CD11a/CD18), CD3, CD4, CD19, and CD25 on leukocytes was studied in another group of volunteers. A 5% decrease in circulating ICAM-1 (P = 0.045 vs. placebo) was found when a single time point (96 h after E2 injection) was studied. However, this decrease was smaller than the intrasubject (day to day) variability observed, and there was no consistent and time-dependent effect of E2 on circulating AMs. Circulating neutrophils increased 2.3-fold over baseline after E2 treatment (P = 0.0008 vs. placebo). The mean coefficients of variation for the intrasubject (day to day) and intersubject variability of circulating AMs were between 5.4-7.5% and 20-29%, respectively. Our findings indicate that the effect of E2 on circulating AMs is not distinguishable from the intrasubject variability observed after placebo treatment. Thus, an effect of E2 on adhesion molecules is unlikely to contribute to the antiatherogenic-cardioprotective effect of E2. The pronounced E2-mediated increase in neutrophils deserves further studies to elucidate its (patho-)physiological implications.

Dexamethasone down-regulates the expression of L-selectin on the surface of neutrophils and lymphocytes in humans.

OBJECTIVE: On the basis of previous animal studies, we hypothesized that dexamethasone may reduce the expression of L-selectin on neutrophils and lymphocytes in healthy men. METHODS: A double-blind, randomized, placebo-controlled, and three-way crossover trial was conducted in nine healthy men. Every subject received four identical infusions of saline solution, 0.04 mg/kg dexamethasone, or 1.0 mg/kg dexamethasone during three observation periods of 48 hours each. RESULTS: Dexamethasone time and dose dependently decreased the L-selectin expression on neutrophils and lymphocytes as measured by flowcytometry. This effect occurred with a time lag of 8 hours after start of treatment: the L-selectin binding index of neutrophils decreased by a maximum of -50% (confidence interval [CI], -37% to -63%) and that of lymphocytes by -26% (CI, -8% to -45%) at 32 hours after the start of treatment with high-dose dexamethasone (p < 0.016). Low-dose dexamethasone had only a transient effect on L-selectin expression of lymphocytes and a less pronounced effect on L-selectin expression of neutrophils. CONCLUSION: Dexamethasone time and dose dependently decreases L-selectin expression on neutrophils and lymphocytes in health men, an effect that is less pronounced than that previously reported for animals.

Partial blockade of nitric oxide synthase blunts the exercise-induced increase of von Willebrand factor antigen and of factor VIII in man.

BACKGROUND: Until now the effects of beta-adrenergic agonists have largely been ascribed to their ability to induce intracellular formation of cyclic adenosine monophosphate. Recently evidence has been accumulating that at least some beta1 and beta2-adrenoceptor effects may be mediated by nitric oxide (NO). Based on these studies, we hypothesized that the beta-adrenoceptor mediated increase of von Willebrand factor and factor VIII-activity (FVIII:C) in plasma during exercise, is caused by an NO-dependent mechanism. METHODS: Thirteen young healthy subjects finished an exhaustive bicycle exercise protocol while they were infused placebo or the NO-synthase inhibitor N-monomethyl-L-arginine (L-NMMA) on two separate days in a randomized, double blind cross-over design. FINDINGS: During exercise systemic haemodynamic changes were parallel in both treatment periods, but L-NMMA caused a partial inhibition of NO-synthase as evidenced by a 30% decrease in exhaled NO. The workload capacities were not different during L-NMMA or placebo infusion. However, under placebo treatment exercise increased vWF-Ag by a maximum of 61% (CI: 43-84; p = 0.002) and FVIII:C by 44% (CI: 31-59; p = 0.001), which was significantly attenuated when subjects were treated with L-NMMA (p <0.05): under L-NMMA treatment vWF-Ag increased by only 25% (CI: 5-51; p = 0.001) and FVIII:C by 12% (CI: 6-39; p = 0.001). INTERPRETATION: Partial blockade of NO-synthase with L-NMMA blunts the exercise-induced increase in vWF-Ag and FVIII:C. Our trial points to a role of endogenous NO-generation in the beta2-adrenergic increase in vWF/FVIII. Thus, we propose that physiologic processes which are induced by systemic beta2-adrenoceptor stimulation may at least partly be mediated by NO.

Elevated circulating P-selectin in insulin dependent diabetes mellitus.

Based on findings that showed increased P-selectin expression on platelets and on choroidal microvessels of patients with insulin dependent diabetes mellitus (IDDM), we hypothesized that also plasma concentrations of circulating (c)P-selectin would be increased in these patients. The aim of this study was to compare the plasma levels of cP-selectin between non-smoking patients with IDDM, treated with an intensified insulin therapy, and healthy controls. The study design was prospective, cross-sectional and analyst-blinded. Subjects were matched individually for sex, age and body mass index. Plasma levels of cP-selectin and of von Willebrand antigen (vWF-Ag) were determined by enzyme linked immunoassays. Forty-two pairs were available for intergroup comparison. Median plasma concentrations of cP-selectin in patients with IDDM (285 ng/ml; interquartile range: 233-372) were on average 21% higher than those of controls (236 ng/ml; interquartile range: 175-296; p = 0.004). Also, median plasma levels of vWF-Ag were 10% higher in patients (96 U/dl; interquartile range: 82-127) than controls (87 U/dl; interquartile range: 70-104; p = 0.025). There was no correlation between plasma concentrations of cP-selectin and vWF-Ag levels in either group (p > 0.05). In conclusion, our results of increased cP-selectin levels are in line with increased P-selectin expression on platelets and on choroidal microvessels found in patients with IDDM. In view of the currently developed small molecule inhibitors of cell adhesion molecules, these independent observations together may provide a sound rationale to select P-selectin as a target for treating or preventing IDDM-associated micro- or macrovascular complications.

Effects of exercise on circulating vascular adhesion molecules in healthy men.

Based on previous studies showing an increase in circulating soluble intercellular adhesion molecule-1 (sICAM-1) after exercise, we hypothesized that exercise may also increase serum levels of the vascular cell adhesion molecule-1 (sVCAM-1) and sE-selection. In a prospective controlled clinical trial, serum levels of sE-selectin, sICAM-1 and sVAM-1 were measured before and after two different exercise protocols in healthy untrained men. Lactate levels increased up to 12.7 mmol/L (95% confidence interval: 10.1-15.9) and 3.6 mmol/L (CI: 2.4-4.7) after ergometry and after an one hour endurance exercise at 60% of the maximal work intensity, respectively (p = 0.028 vs baseline and controls). The maximal increase in lymphocyte counts of 106% (CI: 63-146), which was only of short duration, was higher immediately after ergometry as compared to that observed after endurance exercise (p = 0.028). However, the maximal increase in neutrophil counts of 178% (CI: 120-298) which was seen at 2 hours after endurance exercise was higher than that seen after ergometry (p = 0.028). In contrast, only small changes of circulating adhesion molecules were seen immediately after ergometry: sICAM-1 increased by 11% (CI: 4-25; p = 0.028), and similar tendencies were also observed for sVCAM-1 and sE-selectin. No other consistent and time-dependent changes of circulating adhesion molecules were observed and all differences and changes were < or = 11%. In sum our study provides evidence that recreational sporting activities in untrained healthy subjects at normal altitude have little influence on serum levels of the circulating vascular adhesion molecules sE-selectin, sVCAM-1 or sICAM-1.

Fosinopril decreases levels of soluble vascular cell adhesion molecule-1 in borderline hypertensive type II diabetic patients with microalbuminuria.

Angiotensin converting enzyme inhibitors (ACE-I) are a mainstay for the treatment of heart failure, and of diabetic microalbuminuria. Recently ACE-I have been found to decrease plasma levels of circulating vascular cell adhesion molecule-1 (cVCAM-1) in patients with congestive heart failure. As increased cVCAM-1 levels are pathognomonic for diabetics with microangiopathy, we investigated the effects of ACE-I on plasma levels of cVCAM-1, intercellular adhesion molecule (cICAM-1), and cE-selectin in microalbuminuric diabetics. In addition, the effects of ACE-I on plasma levels of plasminogen activator inhibitor (PAI-1) and of tissue plasminogen activator (TPA) were studied. Fosinopril (10 mg/day) was administered over 12 weeks to 11 microalbuminuric patients with non-insulin-dependent diabetes mellitus (NIDDM). As expected, baseline plasma concentrations of cE-selectin, cICAM-1, and cVCAM-1 were markedly higher in patients than in healthy control subjects (n = 82; P < .001). PAI-1 levels in NIDDM were similar to those in control subjects, whereas TPA levels were about 25% lower in patients than in control subjects (P = .013). Serum levels of cVCAM-1 decreased by -19% (CI: -25% to -13%) after treatment with fosinopril (P = .003) and were no longer different from those of the control group. In contrast, plasma levels of cE-selectin, cICAM-1, PAI-1, and TPA were unaffected. As expected microalbuminuria decreased by -44% (CI: -65 to -22; P = .004). In conclusion, fosinopril lowered cVCAM-1 levels along with microalbuminuria in NIDDM. This may represent a novel mechanism of action of ACE-I in diabetes-associated endothelial dysfunction. Whether decreased VCAM-1 expression is responsible for the observed reduction in microalbuminuria, deserves further investigation.

Recent insights into the molecular genetics of the homocysteine metabolism.

The homocysteine plasma level is determined by non-genetic and genetic factors. In recent years evidence has accumulated that the total homocysteine plasma level of patients under different forms of renal replacement therapy is influenced by a common mutation at nucleotide position 677 of the gene coding for 5,10-methylenetetrahydrofolate reductase (MTHFR 677C-->T). Furthermore, compound heterozygosity for the 677T allele and a novel A-->C polymorphism at nucleotide position 1298 of MTHFR is suggested to correlate with a decrease of folate plasma concentrations. Because polymorphisms of genes coding for proteins involved in the metabolism of homocysteine may contribute to elevated total homocysteine plasma concentrations, molecular genetic analyses of the homocysteine pathways experienced a drift towards screening for candidate genes with a putative relationship to total homocysteine plasma levels. One example is the cloning of the FOLR1 gene coding for the folate-binding protein (Folbp1), which has recently been inactivated in mice, thus representing an elegant model to investigate the consequence on the homocysteine metabolism. Furthermore, the recent characterization of the CUBN gene encoding the intrinsic factor-vitamin B12 receptor (cubilin) provides a basis to identify the causative mutations in patients suffering from a hereditary syndrome of hyperhomocysteinemia that presents with megaloblastic anemia and proteinuria. This review focuses on recent insights into the molecular genetics of MTHFR, FOLR1, and CUBN, and their relationships to the metabolism of the amino acid homocysteine.

Effects of angiotensin-II infusion at pressor and subpressor doses on endothelin-1 plasma levels in healthy men.

Several lines of evidence suggest that effects of angiotensin-II (A-II) could be mediated in part by endothelin-1 (ET-1): A-II enhances production and secretion of ET-1 which in turn may contribute to the pressor effects and mitogenic actions of A-II. We have conducted a randomized controlled cross-over study to investigate whether A-II increases ET-1 plasma levels in humans at pressor doses. Each of the eight healthy male volunteers received a subpressor and pressor dose of A-II which were assessed by titration of the individual dose dependent blood pressure responses to A-II-infusion. The mean subpressor dose of A-II was 0.62 ng/kg/min. (range: 0.31-1.25); the mean pressor dose of A-II was 8.44 ng/kg/min. (range 2.5-20), yielding an average increase in mean arterial pressure by 35% (95% confidence interval [CI]: 24-45%). Plasma ET-1 concentrations increased significantly only in response to pressor doses of A-II (Friedman ANOVA p=0.022): ET-1 increased by 89 % (CI: 24-154%) over baseline (1.7 pmol/L; CI: 1.4-2.0) 60 min. after starting the pressor infusion of A-II and remained elevated throughout the 4-hours observation period. In conclusion, A-II at pressor doses but not at subpressor doses induced an increase in plasma levels of ET- 1 in healthy subjects. This finding may be of relevance for various diseases associated with increased production of A-II and could potentially have therapeutic implications.

Sex differences in concentrations of exhaled nitric oxide and plasma nitrate.

Nitric oxide (NO) is generally considered as an endogenous vasoprotective agent. Various studies indicate that the female sex hormone estradiol, that contributes to the well known gender differences in cardiovascular disease, may enhance NO-production. Thus we studied sex differences in NO-generation by measuring single breath NO-exhalation and plasma levels of nitrate (NO3), the stable endmetabolite of NO. In this observational trial 22 male and 21 female volunteers, 19 to 38 years of age, were studied on 3 days at weekly intervals. Median concentrations of NO were 20 parts per billion (95% CI: 16 to 32 ppb) in women and 34 ppb (95% CI: 31 to 58 ppb) in men. The median plasma concentrations of NO3 were 14 microM/L (95% CI: 11 to 23 microM/L) in women and 27 microM/L (95% CI: 24 to 47 microM/L) in men. Thus, men exhaled 59% more NO (p < 0.001) and had 99% higher NO3 levels than women (p < 0.0001). Even when exhaled NO concentrations were corrected for body weight, men exhaled 50% more NO than women (p = 0.024). No significant changes in measured endpoints were seen during the menstrual cycle (p > 0.05) in women. In view of the diversity of NO-actions, the finding of marked sex differences in NO-production is basic to the elucidation of gender differences in a number of (patho)-physiologic conditions.

[Trends in molecular diagnosis]. / Trends in der molekularen Diagnostik.

The number of characterized monogenic and polygenic diseases is rising each year. In consequence, molecular diagnostics is faced with an ever increasing number of patient samples and with more and more heterogeneous genetic defects. The fusion of microelectronics and molecular biology has created a new technology (microelectronic miniaturization), which provides a rapid, efficient, and cost-effective tool in molecular diagnostics at a high-sample throughput. The biochip has recently been selected as one of the ten scientific highlights in the year 1998. The application of microelectronics ranges from the polymerase chain reaction (PCR), nucleotide sequence analysis via DNA-chips or capillary electrophoresis-chips to gene expression analysis. These microchips are suited for integration into fully automated systems, thus providing the basis for automation of molecular diagnostics. The present article summarizes important trends in molecular diagnostics and provides a glimpse on future technologies.

Insulin sensitivity during oral glucose tolerance test and its relations to parameters of glucose metabolism and endothelial function in type 2 diabetic subjects under metformin and thiazolidinedione.

AIM: This study was designed to assess the usefulness of a model-based index of insulin sensitivity during an oral glucose tolerance test (OGTT) in the identification of possible changes in this metabolic parameter produced by pharmacological agents known to be potent insulin sensitizers, that is metformin (M) and thiazolidinedione (T). The association of these agents with several other factors related to glucose metabolism was also investigated, as well as the relation of insulin sensitivity and secretion with markers of endothelial function such as different adhesion molecules (cAMs), that is vascular cell adhesion molecule-1, intercellular adhesion molecule-1 and E-Selectin. METHODS: Twenty type 2 diabetic patients treated with diet only underwent a 3-h OGTT for measurement of plasma glucose, insulin, proinsulin, C-peptide and cAMs before and after administration of randomly given M (n = 9; 1700 mg/day) or T (n = 11; 600 mg/day). After 16 weeks of treatment, a second OGTT was performed. Insulin sensitivity was calculated with homeostasis model assessment and with oral glucose insulin sensitivity (OGIS), which quantifies dynamic glucose clearance per unit change of insulin. Insulin secretion was assessed by modelling technique. Differences in these parameters before and after treatment, as well as possible relationships with cAMs, were assessed. RESULTS: Basal and stimulated plasma glucose decreased after therapy in both the groups by approximately 20%. Basal insulin resistance also decreased. Insulin sensitivity in dynamic conditions (OGIS: ml/min/m(2)) increased with M (289.3 +/- 18.8 vs. 234.7 +/- 18.1, p < 0.02) and tended to improve with T (323.5 +/- 18.1 vs. 286.8 +/- 22.1, p = 0.09). Total insulin secretion over the OGTT [TIS: nmol/l(3 h)] tended to decrease with M (17.1 +/- 2.5 vs. 27.3 +/- 0.3, p = 0.08) but not with T (23.6 +/- 3.5 vs. 22.5 +/- 2.7). Plasma concentrations of E-Selectin decreased in T (38.0 +/- 2.3 vs. 51.2 +/- 6.1 ng/ml, p < 0.05). No correlation was found between insulin sensitivity and cAMs. CONCLUSIONS: Model-based indices of insulin sensitivity and secretion during an OGTT can be able to detect changes observed in patients under treatment with pharmacological agents such as M or T. Both the drugs improved glucose control similarly. Decreased plasma E-Selectin concentrations were seen in patients on T therapy only.