Differential effects of 17beta-estradiol and testosterone on the contractile responses of porcine coronary arteries.

1. We investigated the effects of short-term exposure to physiological levels of 17beta-estradiol and testosterone on vasocontractile responses in porcine coronary artery rings. 2.

Acute impairment of relaxation by low levels of testosterone in porcine coronary arteries.

Objectives: While there are many suggested reasons for the marked gender bias in cardiovascular events, much of the available data indicate that circulating estrogens are cardioprotective. The possibility that endogenous androgens may be detrimental to the cardiovascular system has received relatively less attention. We investigated the short-term modulatory effects of various concentrations of testosterone on vascular function in isolated porcine coronary artery rings.

Efficacy of treating hypertension in women.

Objective: To assess whether the relative and absolute benefit of hypertension treatment in women varies with age or race.

Design: Systematic review of studies from 1966 to 1998 using MEDLINE, reviews, and consultation with experts. Eleven randomized controlled trials of pharmacologic treatment of prJgiary hypertension with cardiovascular morbidity and mortality outcomes were selected, with a pooled population of 23,000 women.

Acute vision loss in children with autosomal recessive polycystic kidney disease.

Patients with autosomal recessive polycystic kidney disease (ARPKD) often present with renal insufficiency and hypertension. We present two children with ARPKD and end-stage renal disease who developed anterior ischemic optic neuropathy and vision loss. Anterior ischemic optic neuropathy occurs rarely in children and has never been reported in children with ARPKD or end-stage renal disease.

Acute exposure to a low level of testosterone impairs relaxation in porcine coronary arteries.

1. While the gender bias associated with coronary artery disease has been suggested to be partially accounted for by the protective effects of oestrogens, the role of testosterone remains unclear. The aim of the present study was to determine whether vasorelaxation could be affected by acute administration of testosterone with and without 17 beta-oestradiol.

Effect of luminal angiotensin II receptor antagonists on proximal tubule transport.

The proximal tubule can endogenously synthesize and secrete luminal angiotensin II at a concentration approximately 100- to 1000-fold higher than that in the systemic circulation. We have recently shown that this endogenously produced and luminally secreted angiotensin II regulates proximal tubule volume reabsorption, which is a reflection of sodium transport within this segment. In this study, we use in vivo microperfusion of angiotensin II receptor antagonists into the lumen of the proximal tubule to examine the role of the luminal AT1 and AT2 receptor in the regulation of volume reabsorption.

Epstein-Barr virus polymerase chain reaction and serology in pediatric post-transplant lymphoproliferative disorder: three-year experience.

To assess whether the semiquantitative peripheral blood Epstein-Barr virus (EBV) polymerase chain reaction (PCR) test correlates with post-transplant lymphoproliferative disorder (LPD), we compiled the results of the test done over a 3-year period ending July 1997. Six hundred seventy-six tests were done on 185 patients. Four hundred-thirty tests (63%) were negative, 167 (25%) were weak positive, 67 (10%) were moderate positive, and 12 (2%) were strong positive.

Bone mineral density in children with myelomeningocele.

Background: Difficulties with ambulation in patients with myelomeningocele often lead to physical inactivity, osteoporosis, and subsequent development of pathologic fractures.

Objective: The purpose of this study was to examine bone mineral density and biochemical markers of bone metabolism in patients with myelomeningocele.

Design And Methods: A total of 35 patients between 6 and 19 years of age with myelomeningocele (ambulatory and nonambulatory) were randomly chosen at the Texas Scottish Rite Hospital for Children.

Endogenous angiotensin II modulates rat proximal tubule transport with acute changes in extracellular volume.

In the present study, we examined whether the effect of endogenously produced angiotensin II on proximal tubule transport in the male Sprague-Dawley rat is regulated by acute changes in extracellular volume. We measured the magnitude of endogenous angiotensin II-mediated stimulation of transport by sequentially perfusing proximal tubules in vivo, first with an ultrafiltrate-like solution, then by reperfusion of the same tubule with an ultrafiltrate-like solution containing 10(-8) M losartan (angiotensin II receptor antagonist). During volume contraction, 10(-8) M losartan decreased volume reabsorption from 4.

Serum creatinine is a poor marker of glomerular filtration rate in patients with spina bifida.

Serum creatinine is used to estimate the glomerular filtration rate (GFR). The serum creatinine, however, may not accurately reflect the GFR in spina bifida patients, who often have decreased overall muscle mass resulting from spinal cord abnormalities. The relationship between the serum creatinine and GFR (obtained by [(125)I]iothalamate clearance) was examined in a population of spina bifida patients.

Endothelial dysfunction exacerbates the impairment of relaxation by lysophosphatidylcholine in porcine coronary artery.

1. Current evidence suggests that lysophosphatidylcholine (LPC), a component found in oxidized low-density lipoprotein (Ox-LDL), inhibits endothelium-dependent relaxation (EDR) mediated by endothelium-derived relaxing factor (EDRF) and endothelium-derived hyperpolarizing factor (EDHF). An objective of the present study was to characterize the roles of the different elements of EDR in LPC-induced impairment within the porcine coronary artery.

Effect of luminal angiotensin II on rabbit proximal convoluted tubule bicarbonate absorption.

The present in vitro microperfusion study examined the effect of luminal angiotensin II on proximal convoluted tubule (PCT) volume absorption and bicarbonate transport. Neither 10(-11) M, 10(-10) M, nor 2 x 10(-8) M luminal angiotensin II significantly affected PCT transport. When tubules were first perfused with enalaprilat to inhibit endogenous angiotensin II production, addition of 10(-10) M luminal angiotensin II increased volume absorption (0.

Regulation of proximal tubule transport by angiotensin II.

Angiotensin II maintains extracellular volume homeostasis, in part, by regulating proximal tubule transport. Physiological doses of angiotensin II stimulate volume and solute transport in the proximal tubule independent of changes in the glomerular filtration rate. Stimulation of bicarbonate transport primarily occurs via increasing activity of the sodium/hydrogen exchanger and the sodium/bicarbonate cotransporter.

Protein losses in children on continuous cycler peritoneal dialysis.

Peritoneal dialysis can result in significant protein losses through the dialysate effluent. Although protein loss in chronic ambulatory peritoneal dialysis has been examined, it has not been extensively studied in patients on continuous cycler peritoneal dialysis. Such losses can contribute to protein calorie malnutrition, especially in infants and children, many of whom are on continuous cycler peritoneal dialysis.

Effects of a centrally active benzoylpyrrolidine drug on AMPA receptor kinetics.

A newly developed benzoylpyrrolidine drug (BDP-20) that increases the size of fast, excitatory synaptic responses was examined for its effects on the kinetic properties of alpha-amino-3-hydroxy-5-methyl-4-isoxalepropionic acid (AMPA)-type glutamate receptors. When long pulses of glutamate were applied to excised hippocampal patches of the rat, the compound BDP-20 caused an approximately 15-fold reduction in the rate at which responses desensitized and a similar size increase in steady-state currents. In experiments using 1-ms glutamate pulses, BDP-20 prolonged response deactivation by a factor of about four and greatly reduced the depression in the second response when two consecutive glutamate pulses were given.

Effects of heparin on the properties of solubilized and reconstituted rat brain AMPA receptors.

Heparin was found to bind to alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors and to alter their functional properties. AMPA receptors solubilized in 0.4% Triton X-100 bound to a heparin-agarose column and were eluted by 0.

Ultraviolet radiation, thiol reagents, and solubilization enhance AMPA receptor binding affinity via a common mechanism.

The binding properties of membrane-bound or solubilized AMPA (alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid)-type glutamate receptors from rat brain were tested following exposure to ultraviolet (UV) radiation or incubation with the thiol reagent p-chloromercuriphenyl-sulfonic acid (PCMBS). Brief exposure to UV radiation (254 nm) increased [3H]AMPA binding to brain membranes, while binding to soluble fractions decreased. The increase in brain membrane binding was caused by an apparent interconversion of low-affinity [3H]AMPA binding sites into a higher-affinity state.

Endogenous production of angiotensin II modulates rat proximal tubule transport.

There is evidence that angiotensin II is synthesized by the proximal tubule and secreted into the tubular lumen. This study examined the functional significance of endogenously produced angiotensin II on proximal tubule transport in male Sprague-Dawley rats. Addition of 10(-11), 10(-8), and 10(-6) M angiotensin II to the lumen of proximal convoluted tubules perfused in vivo had no effect on the rate of fluid reabsorption.

Renal tubular acidosis and deafness: report of a large family.

The syndrome of distal renal tubular acidosis (dRTA) and sensorineural deafness has been reported in consanguineous families and is believed to be inherited in an autosomal recessive pattern. All affected patients also have nephrocalcinosis. We report here a family with 6 of 12 children affected with this syndrome.

Effect of cyclothiazide on binding properties of AMPA-type glutamate receptors: lack of competition between cyclothiazide and GYKI 52466.

The effects of cyclothiazide on the properties of (R,S)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors were studied using equilibrium binding techniques and interactions with other compounds known to modulate the receptors. Cyclothiazide caused a reduction in [3H]AMPA binding in assays carried out in the presence of thiocyanate, a chaotropic ion that markedly increases the affinity of AMPA receptors and accelerates their desensitization. In the absence of thiocyanate, however, cyclothiazide had no reliable effect on the binding of [3H]AMPA or on the affinity for this agonist assessed from the displacement of [3H]CNQX.

Resolution of hepatitis B virus-related membranoproliferative glomerulonephritis after orthotopic liver transplantation.

The most well-described renal disease associated with hepatitis B virus (HBV) infection is membranous glomerulonephritis; membranoproliferative glomerulonephritis is described much less frequently. The course of HBV-associated renal disease after liver transplantation has not been described to date. We present a 15-year-old girl with HBV-associated membranoproliferative glomerulonephritis and end-stage liver disease, in whom, after cadaver liver transplantation, clinical and histological resolution of renal disease was observed.

Cyclothiazide decreases [3H]AMPA binding to rat brain membranes: evidence that AMPA receptor desensitization increases agonist affinity.

The effects of cyclothiazide, a drug which blocks AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor desensitization, were tested on binding of [3H]AMPA to rat brain membranes. Cyclothiazide reduced [3H]AMPA binding by lowering the apparent affinity of the AMPA receptor. The magnitude of the decrease was temperature dependent and greater for membrane-bound than for solubilized receptors.

Angiotensin II control of the renal microcirculation in rats with reduced renal mass.

It has been suggested that angiotensin II (ANG II) activation after renal ablation contributes to the altered glomerular dynamics and proteinuria that characterizes this model of chronic renal failure. In the present study, male Munich-Wistar rats underwent 75% renal ablation (Nx group). Two weeks later, micropuncture studies were performed in sham-operated rats (sham group) and Nx group rats during intravenous infusion of either a vehicle or two ANG II inhibitors, namely [Sar1, Ala8]ANG II or MK-421 administered at a rate of 0.