Effect of Antihypertensive Drugs on Uric Acid Metabolism in Patients with Hypertension: Cross-Sectional Cohort Study.

Background: Hypertension is a common complication in patients with gout and/or hyperuricemia. Besides, hyperuricemia is a risk factor of gout as well as ischemic heart disease in hypertensive patients. Moreover, the risk of gout is modified by antihypertensive drugs. However, it remains unclear how antihypertensive agents affect uric acid metabolism. Purpose: In the present study, we investigated the uric acid metabolism in treated hypertensive patients to find out whether any of them would influence serum levels of uric acid. Patients and methods: 751 hypertensive patients (313 men and 438 women) under antihypertensive treatment were selected. Blood pressure (BP), serum uric acid (SUA) and serum creatinine (Scr) were measured and evaluated statistically. Results: In patients treated with diuretics, beta-blockers and/or alpha-1 blockers SUA levels were significantly higher than in patients who were not taking these drugs. Besides, the estimated glomerular filtration rate (eGFR) in patients treated with diuretics, beta-blockers and/or alpha-1 blockers was negatively correlated with SUA level. There were gender differences in the effects of beta-blockers and alpha-1 blockers. Multiple regression analysis indicated that both diuretics and beta-blockers significantly contributed to hyperuricemia in patients with medication for hypertension. Conclusion: Diuretics, beta-blockers and alpha-1 blockers reduced glomerular filtration rate and raised SUA levels. Calcium channel blockers, ACE inhibitors and angiotensin receptor blockers, including losartan, did not increase SUA levels.

Effect of glucose concentration on foam cell formation in THP-1 cells.

We investigated whether a high glucose condition could affect cholesterol ester (CE) synthesis and accumulation of cholesterol in arterial wall cells by using the human monocytic cell line THP-1. After 24-hour PMA treatment, cells were grown in control (200 mg/dl of glucose) or high glucose concentration (400, 600, 800, or 1,600 mg/dl) medium for 6 days. CE synthesis was then investigated in cells incubated with 50 microg/ml of native, glycated, acetylated, or oxidized LDL. Cells grown in 400 mg/dl of glucose showed a significant increase of CE synthesis regardless of whether they were incubated with native, glycated or oxidized LDL, compared with cells grown in 200 mg/dl of glucose. In parallel with the studies of CE synthesis, the intracellular accumulation of CE also increased in cells grown in 400 mg/dl of glucose when incubated with oxidized LDL (50 microg/ml), compared with that in cells grown in 200 mg/dl of glucose. The amount of oxidized LDL associated with cells grown in 400 mg/dl of glucose was markedly higher than that in cells grown in 200 mg/dl of glucose. This suggests that there is an optimal glucose concentration (400 mg/dl) which increases the number of some scavenger receptors (receptors for oxidized LDL) expressed on cells, and might increase and stimulate CE synthesis, resulting in intracellular accumulation of CE in macrophage. A high blood glucose concentration could change the metabolism of arterial wall cells and play an important role in the pathogenesis of vascular complications of diabetes mellitus.

[Syndrome X].

Insulin resistance is an early and major feature in the development of non-insulin-dependent diabetes mellitus(NIDDM). It is also associated with hyperlipidemia, hypertension, obesity and cardiovascular disease. It is the clustor of the risk factors for atherosclerosis and recognized as 'insulin-resistance syndrome' (Syndrome X). Central (abdominal) obesity is much more strongly associated with insulin resistance than overall obesity. The increase of both the influx of free fatty acid to liver and the production of TNF-alpha in adipose tissue may play an important role in mechanism of insulin resistance associated with central obesity. Calorie restriction and weight loss improve insulin sensitivity in overweight humans. Exercise training also improves insulin sensitivity via increased oxidative enzymes, glucose transporters (GLUT4) and capillarity in muscle as well as by reducing abdominal fat. The new 'glitazones' (thiazolidinediones) is used clinically to improve insulin sensitivity.

Antigen-induced elevation of immunoreactive endothelin-1 (ET-1) levels in ovalbumin-sensitized guinea pig airway tissue.

Changes in the immunoreactive ET-1 levels during the anaphylactic reaction of airway tissue from ovalbumin-sensitized guinea pigs were investigated. ET-1-immunoreactivity (ET-IR) was detected in the epithelial and smooth muscle layers of tracheal sections from normal guinea pigs and it was enhanced slightly by phosphoramidon (1 microM) treatment. The ET-IR level of the epithelial layer of ovalbumin-treated tissue from actively sensitized animals was slightly higher than that from normal animals, but it was enhanced markedly by phosphoramidon (1 microM) treatment. Furthermore, the mean ET-IR level of homogenates of antigen-treated tracheal tissues from sensitized guinea pigs (22.8 +/- 1.55 fmol mg-1 protein, n = 5) was significantly higher than the corresponding normal level (12.3 +/- 1.21 fmol mg-1 protein, n = 5). These results suggest that increased epithelial airway ET-1 levels contribute to the anaphylactic reaction of guinea pig airways.

[Primary hypertriglyceridemia].

Familial hypertriglyceridemia has been suggested to be an autosomal dominant condition with age-dependent penetrance, but so far the underlying defective gene has not been elucidated. LPL gene and apolipoprotein A-I/C-III/A-IV gene cluster might be involved in familial clustering of hypertriglyceridemia. Heterozygous LPL deficiencies caused by several types of gene mutation are known to result in a partial defect in catabolism of VLDL, occurring mild to moderate hypertriglyceridemia. However, although the mutation of LPL gene results in reduced lipolytic activity, this type of dyslipidemia appears to manifest only if VLDL-TG production is also increased. These suggest that overproduction of VLDL-TG is a more important cause of hypertriglyceridemia than is the LPL deficiency. Moreover, families with a clustering of hypertriglyceridemia are known to be at increased risk of hyperinsulinemia due to impaired insulin sensitivity. Impaired insulin sensitivity and hyperinsulinemia are the major determinants of excessive VLDL-TG synthesis and dyslipidemia. Taken together, abnormally high production of VLDL-TG seemed to be the major factor in causing familial hypertriglyceridemia, but clearance capacity can play an important role in determining the severity of the TG elevation.

Anti-angiogenic effect of TGFbeta in aqueous humor.

Neovascularization is mediated by various factors in ocular tissues. Recent studies have emphasized the role of vascular endothelial growth factor in the induction of angiogenesis. We have previously reported that aqueous humor (AH) suppressed vascular endothelial cell growth and angiogenesis. We speculated that the anti-angiogenic effect of AH is mediated by transforming growth factor beta (TGFbeta). In order to clarify the presence of TGFbeta in bovine AH, we applied it on the heparin-sepharose affinity column and prepared two fractions (bound and unbound fractions). We measured TGFbeta concentration in each fraction and examined how the anti-TGFbeta antibody decreased the inhibitory effect of AH on human umbilical vein endothelial cell growth and on in vitro angiogenesis. We found the presence of TGFbeta2, but not TGFbeta1, in the heparin bound fraction, and the inhibitory effect was detected in the heparin-bound fraction. Anti-TGFbeta antibody completely and dose-dependently extinguished the inhibitory effect of AH. We propose that the inhibitory effect of AH on endothelial cell growth and in vitro angiogenesis are both mediated by TGFbeta2. Our results indicate TGFbeta2 is normally present in AH and protects the eye tissue against abnormal neovascularization.

Modification of the N-terminal cysteine of plasma cholesteryl ester transfer protein selectively inhibits triglyceride transfer activity.

An invariant cysteine residue is found at the N-terminus of cholesteryl ester transfer protein (CETP) isolated from plasma of humans, rabbits and cynomolgus monkeys. We previously reported the expression of recombinant rabbit cholesteryl ester transfer protein in yeast (Kotake et al., J. Lipid Res. 1996; 37: 599-605). The recombinant CETP secreted into the medium contains an altered N-terminal sequence but was fully capable of facilitating both cholesteryl ester (CE) and triglyceride (TG) transfer between lipoproteins. We investigated the importance of the conserved N-terminal cysteine of plasma CETP in the lipid transfer activity by chemical modification of the free sulfhydryl groups of the recombinant CETP and CETP from human and rabbit plasma. The unmodified forms of these CETPs had similar specific activities of CE and TG transfer. Neither 5,5'-dithiobis-(2-nitrobenzoate) nor N-ethyl maleimide altered the lipid transfer activity. In contrast, p-chloromercuriphenyl sulfonate selectively inhibited the TG transfer activity of both human and rabbit plasma CETP. The TG and CE transfer activities of the recombinant CETP, which lacks the N-terminal cysteine residue, was not affected. These results demonstrate that the N-terminal cysteine residue of both human and rabbit plasma CETP is free and is likely to be involved in the construction of a critical part of the active site of CETP that can determine the selectivity of the lipid molecule for the transfer reaction.

Apolipoprotein E Sendai (arginine 145-->proline): a new variant associated with lipoprotein glomerulopathy.

Lipoprotein glomerulopathy (LPG) is a novel disease characterized by proteinuria, lipoprotein thrombi in the glomeruli, and increased concentration of plasma apolipoprotein (apo) E. It is believed that a genetic disorder of apo E may be present and associated with the disease. Three patients with LPG were examined in this study. The patients' DNA sequences were analyzed, and a nucleotide G to C point mutation in exon 4 of the apo E gene was confirmed in each patient. This missense mutation denotes amino acid substitution of the proline residue for arginine residue at position 145 of apo E. This variant (apo E Sendai) may cause a marked molecular conformational change of the apo E. These findings suggest that a novel variant is etiologically related to LPG.

Effects of enalapril on the exercise capacity and neurohumoral factors during exercise in patients with chronic heart failure.

The effects of enalapril on exercise capacity and neurohumoral factors during exercise were evaluated in 10 patients with heart failure. Echocardiograms and exercise testing with expired gas analysis were performed before and after enalapril. Blood samples were obtained before and after exercise. Both ejection fraction and percent fractional shortening increased with enalapril (p < 0.05). The anaerobic threshold and peak VO2 did not change with enalapril. Epinephrine and norepinephrine levels at peak exercise decreased with enalapril (p < 0.1). Plasma renin both at rest and at peak exercise increased with enalapril (p < 0.1). Angiotensin II was lower after enalapril both at rest and at peak exercise (p < 0.1 and p < 0.05, respectively). Aldosterone was lower after enalapril both at rest and at peak exercise (p < 0.05). Atrial natriuretic peptide (ANP) was lower after enalapril both at rest and at peak exercise. There was no significant correlations between peak VO2 and changes in neurohumoral factors before and after enalapril during exercise. In conclusion, neurohumoral changes with enalapril occurred during exercise even if exercise capacity did not improve. Moreover, the improvement of cardiac function at rest and neurohumoral factors with enalapril did not lead to a change of exercise capacity.

Synergistic actions of pentobarbital and dihydropyridine Ca2+ antagonists on guinea pig isolated thoracic aorta.

In order to elucidate the mechanism(s) behind the interactions between barbiturates and Ca2+ antagonists, the effects of pentobarbital combined with three structurally diverse types of Ca2+ antagonist on CaCl2-induced contractile responses of the guinea pig thoracic aorta in Ca(2+)-free and 40 mM K+ medium and the effects of pentobarbital on Ca2+ antagonist binding to guinea pig aortic membranes were investigated. The dihydropyridine derivatives isradipine (10(-10)-10(-8) M) and nifedipine (10(-10)-10(-8) M) inhibited CaCl2-induced contractions concentration-dependently. Treatment with both pentobarbital (10(-4) M) and dihydropyridine Ca2+ antagonists (10(-9) M) shifted the CaCl2 concentration-response curves to the right significantly compared with those after treatment with the Ca2+ antagonists and pentobarbital alone. However, no synergistic effects of pentobarbital (10(-4) M) with other types of Ca2+ antagonist (verapamil (10(-7) M) and diltiazem (10(-6) M)) were observed. The binding of [3H]isradipine (2 x 10(-9) M) to guinea pig aortic membranes was increased significantly by simultaneous pentobarbital treatment, but no such effect was observed with [3H]verapamil (10(-8) M) or [3H]diltiazem (2 x 10(-8) M). These findings suggest that the synergistic contractile effects of pentobarbital and dihydropyridines were, in part, due to enhancement of dihydropyridine binding to guinea pig aortic membranes (L-type Ca2+ channels) by pentobarbital and that the interactions between pentobarbital and Ca2+ antagonists may be structurally specific.

Neural BC1 RNA in mouse skeletal muscle is a denervation-induced RNA whose expression is developmentally regulated.

We detected neural BC1 RNA in mouse skeletal muscle. The level of BC1 RNA was high in the fetus, but it declined progressively to the adult level as development proceeded. These observations suggest that this RNA is involved in the prenatal development and differentiation of muscles. Although its developmental expression correlates with the fetal period of polyneuronal innervation, BC1 RNA does not seem to play a direct role(s) in synaptogenesis, since its expression was not restricted to the neuromuscular junction. We also demonstrated that the BC1 RNA level in adult muscle was elevated after denervation, suggesting that changes in the activity of muscles or neural factors caused by axotomy, or both may result in BC1 RNA upregulation.

Human arterial smooth muscle cell proliferation in diabetes.

In the present study, we focus on the proliferation of human arterial smooth muscle cells (SMCs) from NIDDM patients (DM-SMCs) to clarify the reactivity to the growth factor(s) in fetal calf serum (FCS) and the factor(s) secreted by T-cells. The proliferation of DM-SMCs was significantly greater than SMCs from nondiabetic patients (nonDM-SMC). DM-SMC conditioned medium (DM-condMed) increased the growth of nonDM-SMCs. These results suggest that the growth factor is secreted from DM-SMCs as an autocrine system, which increases the proliferation of nonDM-SMCs. T-cells increased DNA synthesis of SMCs, and DM-SMCs strikingly reacted to T-cells. The present results support a function of T-cells in stimulating SMC growth. In conclusion, human arterial SMC proliferation is increased in diabetes in the same fashion as in experimentally induced diabetes in animals through responses to growth factors and an increased autocrine system. These results provide a mechanism for the increase in atherosclerotic disease in diabetes.

Ammonia response to exercise in patients with congestive heart failure.

OBJECTIVE: To assess energy depletion in skeletal muscle in patients with congestive heart failure by measuring blood purine metabolites during exercise and, at the same time, determine the implications of the ammonia response to exercise in these patients. SETTING: Tottori University Hospital, Yonago, Japan. PATIENTS: 49 heart failure patients (New York Heart Association (NYHA) grades I-III) and 16 normal subjects. MAIN OUTCOME MEASURES: Blood lactate, ammonia, and hypoxanthine levels were measured during exercise with expired gas analysis. RESULTS: In normal exercising subjects as well as in each heart failure subgroup, the ammonia threshold was significantly higher than both the lactate threshold [control: 21.8 (SD 5.3) v 17.4 (3.3) ml/kg/min; NYHA class I: 18.9 (3.8) v 15.5 (2.6); class II: 14.8 (2.5) v 12.7 (2.4); class III: 13.5 (2.6) v 11.8 (2.5)] and the ventilatory threshold (P < 0.01). The difference between the ammonia and lactate thresholds was noted in all normal subjects and in all heart failure patients. The ammonia threshold, however, was significantly lower in heart failure patients than in normal subjects and it decreased with increasing NYHA class (P < 0.01). Maximum ammonia levels were lower in the heart failure group and decreased further with higher NYHA classifications [control: 198 (52) mg/dl; NYHA class I: 170 (74); class II: 134 (58); class III: 72 (15); P < 0.01]. There were significant correlations between maximum ammonia values and maximum lactate, oxygen consumption, and hypoxanthine levels (r = 0.74, 0.48, and 0.87, respectively; P < 0.001). CONCLUSIONS: The ammonia threshold may reflect the onset of ATP depletion in exercising skeletal muscles, as opposed to the onset of anaerobic respiration. It seems therefore that energy depletion in skeletal muscles during exercise occurs after attaining the anaerobic threshold. Both aerobic and anaerobic capacities of skeletal muscle are reduced in patients with congestive heart failure.

Expression and secretion of rabbit plasma cholesteryl ester transfer protein by Pichia pastoris.

The rabbit cholesteryl ester transfer protein (CETP) was expressed in the methylotrophic yeast Pichia pastoris by introducing the CETP cDNA under the control of the methanol-inducible alcohol oxidase promoter. The cDNA was cloned from in vitro amplified cDNA of rabbit liver mRNA. The nucleotide sequence of the cloned cDNA differed slightly from the previously published sequence that changed the amino acid sequence in six residues. Interestingly, five of these replacements are identical to the corresponding residues in human CEPT. In addition, the encoded mature N-terminal sequence was changed from Cys- to Arg-Glu-Phe- to link the CETP sequence to the yeast acid phosphatase signal peptide. The culture medium of the transformed cells induced with 1% methanol contained both cholesteryl ester and triglyceride transfer activity comparable to that of rabbit plasma. Like rabbit plasma, the lipid transfer activity in the medium could be inhibited by monoclonal antibodies that block CE/TG transfer or TG transfer alone. Immunoblot analysis of M(r) = 80 K and minor species of M(r) = 60-100 K. In spite of these differences, the specific transfer activity of the recombinant CETP was indistinguishable from that of rabbit plasma CETP of M(r) = 74 K. N-Glycosidase F treatment converted both the recombinant and plasma CETP to a single species of M(r) = 55 K. Both the plasma and recombinant CETP lost their activity after removal of N-linked carbohydrate and sialic acid. A single 55 K component was found in the cell-lysates. The intracellular form of the recombinant CETP was not modified by N-glycosidase F treatment. In conclusion, the recombinant CETP is synthesized as an inactive polypeptide that is processed and secreted as a functional glycoprotein. In addition, the N-terminal Cys residue of the plasma CETP is not required for its activity.