Biomedical subjects

W F Keane

Publications and source records attributed to W F Keane.

At least 145 records · Page 8Linked to original sources

PubMed1987

Opioid-mediated suppression of interferon-gamma production by cultured peripheral blood mononuclear cells.

Mounting evidence suggests that opiate addiction and stress are associated with impaired cell-mediated immunity. We tested the hypothesis that morphine and the endogenous opioid beta-endorphin (beta-END), a pituitary peptide released in increased concentrations during stress, can suppress the production of the key macrophage-activating lymphokine interferon-gamma (IFN-gamma) by cultured human peripheral blood mononuclear cells (PBMNC). Using a radioimmunoassay to measure IFN-gamma, we found that exposure of PBMNC to biologically relevant concentrations of both opioids significantly inhibited IFN-gamma generation by cells stimulated with concanavalin A and varicella zoster virus. Studies of the mechanism of suppression revealed (a) a classical opioid receptor is involved (suppression was antagonized by naloxone and was specific for the NH2 terminus of beta-END), (b) monocytes are the primary target cell for opioids (monocyte-depleted lymphocyte preparations showed little suppression), and (c) reactive oxygen intermediates (ROI) and prostaglandin E2 are important mediators (scavengers of ROI and indomethacin eliminated the suppression). Based on these findings we suggest that opioid-triggered release of inhibitory monocyte metabolites may play a role in the immunodeficiency associated with narcotic addiction and stress.

Blood Cells↗

PubMed1987

Mechanism of Escherichia coli alpha-hemolysin-induced injury to isolated renal tubular cells.

Alpha-hemolysin (AH) is a 110,000-dalton protein secreted extracellularly by certain Escherichia coli. This protein is an acknowledged virulence factor for E coli and recently has been implicated as an important determinant in the pathogenesis of E coli pyelonephritis. Recombinant engineered strains of E coli were used that varied only in their ability to secrete AH extracellularly. The effect of AH on vital dye exclusion, oxygen consumption rate (QO2) adenosine triphosphate (ATP) levels, superoxide (O2-) and hydrogen peroxide (H2O2) production in preparations of isolated rat cortical renal tubular cells (RTCs) was assessed. Approximately 5-10 pg of AH dramatically stimulated QO2 by nearly 150%. This was associated with a marked increase in production of O2- and H2O2, to 13.9 +/- 1.7 and 13.2 +/- 2.1 nM/mg cell protein, respectively (P less than 0.05), as well as a 38% decrease in cellular ATP. These biochemical effects were all seen after a 30-minute exposure to AH and by 120 minutes were associated with 15.7% +/- 1.1% of RTCs that were unable to exclude vital dye. The effect of AH on QO2 and O2- formation was prevented by pretreatment of RTCs with ouabain, which indicates that the effect of AH on oxygen metabolism is linked to Na-K ATPase activity. However, when ouabain-treated RTCs were exposed to AH, ATP remained depressed despite the inhibition of QO2 and O2- production. In contrast, in ouabain-pretreated RTCs, cell membrane integrity was dramatically protected, because only 2.4% +/- 0.4% of RTCs were not unable to exclude vital dye. Thus, the data demonstrate that E coli AH provokes at least two biochemical events that may be injurious to RTC: increased oxygen intermediates (O2- and H2O2 and ATP depletion. These findings with ouabain suggest that the first mechanism of injury may be a more proximate cause of cell death. Moreover, the data suggest that endogenous production of reactive oxygen molecules may be critical modulators of RTC membrane injury.

Adenosine Triphosphate↗

PubMed1987

Beta-endorphin stimulates human polymorphonuclear leukocyte superoxide production via a stereoselective opiate receptor.

Opioid peptides have been shown to modulate the function of cells associated with host defense. Both opiate and nonopiate receptor mechanisms have been shown to mediate cell responses to these peptides. In this study we used a ferricytochrome C reduction microassay to measure superoxide (O2-) production by human polymorphonuclear leukocytes after stimulation with beta-endorphin (beta-END). beta-END was found to stimulate O2- release at concentrations from 10(-14) to 10(-8) M; the peak response occurred at 10(-12) M. A microassay based on the horseradish peroxidase-mediated oxidation of phenol red was used to demonstrate the production of hydrogen peroxide H2O2, by beta-END at 10(-12) M. The accumulation of H2O2 was reduced by the inhibitor, nitroprusside, and by the converting enzyme, catalase. The accumulation of O2- in response to the potent chemotactic peptide formyl-methionine-leucine-phenylalanine was studied and a distinctly different dose-response profile with a peak response at 10(-8) M was observed. Because beta-END can apparently bind to and activate cellular functions by nonopiate receptors, N-acetyl-beta-END was tested. At doses between 10(-14) and 10(-8) M, it failed to effect O2- accumulation. Moreover, (-)-naloxone 10(-12) M was shown to completely abolish the stimulatory effect of equimolar beta-END whereas (+)-naloxone was entirely ineffective. At 10(-8) M both stereoisomers also failed to inhibit formyl-methionine-leucine-phenylalanine 10(-8) M. Thus, at the picomolar concentration present in the human systemic circulation, beta-END activates oxygen metabolism by polymorphonuclear leukocytes through stereoselective, naloxone-sensitive opiate receptors.

Endorphins↗

PubMed1987

Comparison of antihypertensive, renal hemodynamic, and humoral effects of pinacidil and hydralazine monotherapy.

The antihypertensive, renal hemodynamic, and humoral effects of pinacidil and hydralazine monotherapy were compared in a double-blind study. Supine diastolic blood pressure decreased with pinacidil (n = 14) from 96.5 to 82.6 mmHg (p less than 0.05), after a mean of 8.5 weeks at a mean dose of 64.3 mg/day, and with hydralazine (n = 15) from 101.5 to 94.0 mmHg (p less than 0.05), after 8.3 weeks at a dose of 163.3 mg/day. Renal plasma flow, glomerular filtration rate, and urinary albumin excretion did not change with pinacidil or hydralazine therapy. Neither agent altered plasma renin activity. Supine and upright plasma aldosterone concentrations decreased significantly during pinacidil, but not during hydralazine, therapy. Thus, both pinacidil and hydralazine reduced blood pressure and preserved renal function. During pinacidil therapy, plasma aldosterone concentrations decreased, whereas plasma renin activity did not. The mechanism of this response is unclear.

Adolescent↗

PubMed1987

Effects of cyclosporine on the isolated perfused rat kidney.

Although cyclosporine (CsA) has been shown to cause decreased renal function in humans, the mechanisms important in cyclosporine nephrotoxicity are not well understood. Investigations of cyclosporine nephrotoxicity in animal models have been complicated by systemic toxic effects not seen in humans. In the present study, the direct renal effects of cyclosporine were investigated in the isolated perfused rat kidney (IPRK) model. Cyclosporine delivered by nontoxic liposomes had no effect on IPRK resistance, perfusate flow, inulin clearance, or fractional reabsorption of sodium, despite marked tissue accumulation of CsA (55.1 +/- 7.2 micrograms/g kidney tissue). In contrast, a 63% decrease in inulin clearance was observed following the administration of intravenous cyclosporine (0.1 ml). However, similar changes in IPRK function were seen after the administration of 0.1 ml of the intravenous cyclosporine vehicle, cremophor, suggesting that the alterations in function were secondary to the vehicle. All together, these findings suggest that cyclosporine nephrotoxicity may be secondary to renal innervation, toxic metabolites, or other systemic effects of cyclosporine not present in the IPRK.

Animals↗

PubMed1986

Intracellular survival of Candida albicans in peritoneal macrophages from chronic peritoneal dialysis patients.

Candidal peritonitis is a tenacious infection in patients undergoing chronic peritoneal dialysis. Since little is known about host defenses of the human peritoneal cavity against fungi, we investigated the interaction of peritoneal macrophages (PM phi) from uninfected dialysis patients with Candida albicans blastospores. Chemiluminescence (CL) techniques were used to assess the respiratory burst activity of these cells, and candidacidal activity was evaluated with a fluorochrome microassay. In sharp contrast to peripheral blood polymorphonuclear leukocytes (PMNs) from healthy donors, which gave a brisk luminol-enhanced CL response to opsonized blastospores and killed 35% of cell-associated organisms, PM phi produced barely detectable luminol-enhanced CL and killed only 13% of intracellular Candida. These findings appeared to be associated with a decreased level of myeloperoxidase in PM phi. The mechanism of intracellular survival of C albicans also appeared to be related to relatively poor triggering of superoxide production during phagocytosis of viable blastospores. The CL response of PMNs to C albicans was opsonin-dependent, and peritoneal dialysis effluent was devoid of opsonic activity. These studies suggest that local cellular and humoral mechanisms of defense are inadequate for protection of peritoneal dialysis patients against candidal peritonitis.

Acridine Orange↗

PubMed1986

Effects of carbohydrate restriction on renal injury in the obese Zucker rat.

The obese Zucker rat model of nonimmune-mediated, spontaneous focal glomerulosclerosis is ideally suited to study the influence of diet on the initiation and progression of glomerular injury. Young (6 wk) and old (33 wk) lean and obese female Zucker rats were fed a carbohydrate-restricted diet intermittently for 27 wk. Carbohydrate restriction resulted in lower body weight (460 +/- 16 versus 310 +/- 7 g, p less than 0.025), kidney weight (1.26 +/- 0.04 versus 1.07 +/- 0.05 g, p less than 0.025), and glomerular area (6930 +/- 290 versus 5780 +/- 230 micron2, p less than 0.025) in young obese Zucker rats compared to ad libitum-fed rats. Although urine-albumin excretion was substantially reduced by carbohydrate restriction in young obese Zucker rats (41.1 +/- 12.3 versus 6.9 +/- 2.9 mg/24 h, p less than 0.01), glomerular injury was not significantly altered. In old obese rats, carbohydrate restriction did not significantly reduce albuminuria or prevent the progression of glomerular injury. Thus, intermittent carbohydrate restriction failed to alter significantly either the initiation of glomerular injury in young, or the progression of nephron damage in old, obese Zucker rats.

Albuminuria↗

PubMed1986

Renal effects of angiotensin II: modulation by calcium and cyclooxygenase products.

Modulation of angiotensin II effects on renal function by extracellular calcium levels and cyclooxygenase products was evaluated using the isolated perfused rat kidney. Kidneys from normal male Sprague-Dawley rats were perfused at constant pressure. After base-line assessment of function, angiotensin II was administered as a bolus and constant infusion; group 1 with normal ionized calcium and 1.2 ng/min angiotensin II, group 2 with normal ionized calcium and 0.6 ng/min angiotensin II, group 3 with low ionized calcium and 1.2 ng/min angiotensin II, and group 4 with indomethacin, low ionized calcium, and 1.2 ng/min angiotensin II. Angiotensin II caused a marked fall in inulin clearance (CIn) in groups 1 and 2. With low ionized calcium (group 3), angiotensin II increased resistance to the same degree as in group 2, but in contrast to group 2, CIn was unchanged. Kidneys perfused with indomethacin (group 4) had marked angiotensin II-induced declines in CIn that rapidly returned to base line despite persistently elevated resistance. Thus the results demonstrated that both calcium and cyclooxygenase products may directly modulate the effects of angiotensin II on renal function. These effects involve more than modulation of angiotensin II-induced vasoconstriction.

Angiotensin II↗

PubMed1986

Effects of nephron loss on glomerular hemodynamics and morphology in diabetic rats.

Loss of renal mass in rats with experimental diabetes mellitus leads to exaggerated hypertrophy of remaining nephrons and accelerated diabetic glomerulopathy. To examine factors responsible for glomerular injury in this setting, rats with preexisting diabetes were subjected to unilateral nephrectomy. Micropuncture studies and evaluation of glomerular morphology were performed 2-3 mo later. Nephrectomized diabetic rats demonstrated significant increases in kidney weight, superficial nephron glomerular filtration rate, and superficial nephron plasma flow compared with two-kidney diabetic rats and nephrectomized nondiabetic controls. Glomerular capillary hydraulic pressure was comparable in two-kidney and nephrectomized diabetic rats and was significantly reduced compared with nephrectomized nondiabetic controls. Nephrectomized diabetic rats demonstrated significant albuminuria, mesangial matrix expansion, and focal glomerulosclerosis, whereas two-kidney diabetic rats and nephrectomized nondiabetic controls showed only minimal alterations in glomerular morphology. It is concluded that diabetic rats can undergo glomerular functional compensation in response to nephron loss. Moreover, accelerated glomerular injury caused by nephron loss in diabetic rats could not be attributed to increased glomerular capillary pressure.

Animals↗

PubMed1986

Enhancement of endotoxin-induced isolated renal tubular cell injury by toxic shock syndrome toxin 1.

The pathogenesis of toxic shock syndrome (TSS) remains unknown. On the basis of experimental data, it has been hypothesized that staphylococcal TSS Toxin 1 (TSST-1) may interact synergistically with low levels of endotoxin and give rise to many of the clinical findings. We have demonstrated previously that lipid A, the biologically active component of lipopolysaccharide (LPS), or endotoxin, induces dose-dependent necrosis of isolated rat renal tubular cells (RTCs). In the present studies, the authors investigated whether this injury could be augmented by TSST-1. The viability of RTCs was assessed by vital dye exclusion. Incubation of freshly isolated rat RTCs with either 1 ng/ml of TSST-1 or 0.1 ng/ml LPS or lipid A had minimal cytotoxicity (less than 6%). Exposure of RTCs to 1 ng/ml TSST-1 for 20 minutes, followed by washing, resulted in a significant enhancement of cytotoxicity when RTCs were exposed to 0.1 ng/ml LPS or lipid A. The sensitization of RTCs by TSST-1 to LPS- or lipid-A-induced injury was prevented by methylamine and chloroquine, two inhibitors of receptor-mediated endocytosis (RME). Chelation of extracellular calcium by 2 mM EGTA also blocked the TSST-1-induced sensitization of RTCs to LPS or lipid A. Inhibition of RTC arachidonic acid metabolism by methylprednisolone, indomethacin, ibuprofen, and piriprost significantly inhibited RTC necrosis induced by TSST-1 and LPS or lipid A by 33-62%. Thiourea and deferoxamine, agents which ameliorate oxidant injury, also inhibited this synergistic injury by 34-67%. Thus, TSST-1 enhanced the cytotoxic effects of LPS/lipid A, and the sensitization of RTCs appeared to involve RME or TSST-1. Oxidative metabolism of arachidonic acid and generation of reactive oxygen species appeared to participate in LPS/lipid-A-mediated RTC death.

Animals↗

PubMed1986

Lack of pharmacodynamic interaction between pentoxifylline and warfarin in the rat.

Pentoxifylline is a new hemorrheologic agent which decreases platelet aggregation and reduces fibrinogen levels. Its ability to affect the coagulation cascade was studied in rats with and without the coadministration of warfarin. There was no significant difference between the prothrombin time ratio (PTR) of the warfarin group (1.51 +/- 0.38) and the combination drug group (1.47 +/- 0.30) at 6 hours. Likewise, there was no significant difference between the PTR of the control group (1.09 +/- 0.07) and the group administered pentoxifylline alone (1.05 +/- 0.06). Although the mechanisms of action of the two drugs may overlap, the pharmacodynamic activity of warfarin was not significantly altered when pentoxifylline was coadministered.

Animals↗

PubMed1985

Glomerular mesangium: its function and relationship to angiotensin II.

The glomerular mesangium is composed of mesangial cells and an intercellular material, the mesangial matrix. Partly because of its unique anatomic location, the mesangium appears to be susceptible to immune- and non-immune-mediated injury. Mesangial cells have characteristics similar to smooth muscle cells, and their surface is covered with receptors that bind a variety of vasoactive substances. The glomerular mesangium seems to play an important role in the physiologic regulation of the glomerular microcirculation. There is evidence that a plasmic flow carrying macromolecules circulates through the mesangium. Changes in glomerular hemodynamic determinants and in the release and/or production of vasoactive substances, particularly angiotensin II, can greatly influence the mesangial movement of macromolecules. Quantitative and/or qualitative alterations in the mesangial movement of macromolecules may lead to mesangial injury.

Angiotensin II↗

PubMed1985

The assessment of risk factors in 462 patients with acute renal failure.

Risk factors associated with the mortality of patients with acute renal failure (ARF) were investigated. This was accomplished by a review of 462 patients with ARF and the utilization of a logistic regression analysis to develop a model that can be used to predict the mortality odds for an ARF patient. The significant risk factors were age, oliguria, pulmonary and cardiovascular complications, jaundice, and hypercatabolism. Based on these factors, our model was able to account for 77% of the mortality associated with ARF.

Acute Kidney Injury↗

PubMed1985

Cefotaxime and desacetyl cefotaxime kinetics in renal impairment.

Cefotaxime and desacetyl cefotaxime kinetics after a single, 1 gm intravenous dose were evaluated in five groups of subjects: group I, normal creatinine clearance (CLCR greater than 90 ml/min); group II, mild renal insufficiency (CLCR 30 to 89 ml/min); group III, moderate renal insufficiency (CLCR 16 to 29 ml/min); group IV, severe renal insufficiency (CLCR 4 to 15 ml/min); and group V, end-stage renal disease requiring maintenance hemodialysis (CLCR less than 6 ml/min). The steady-state volume of distribution (Vss) ranged from 10% to 55% of body weight but was not related to CLCR. The terminal t1/2 values of cefotaxime and desacetyl cefotaxime were 0.79 and 0.70, 1.09 and 3.95, 1.55 and 5.65, 2.54 and 14.23, and 1.63 and 23.15 hours in groups I to V, respectively. There were no significant changes in Vss or t1/2 after multiple dosing, but there were significant correlations between CLCR and cefotaxime total body clearance, cefotaxime and desacetyl cefotaxime renal clearance, and cefotaxime nonrenal clearance. Dosage regimens for the use of cefotaxime in patients with renal impairment are proposed.

Acute Kidney Injury↗

PubMed1985

Antimicrobial activities of dialysate-elicited and resident human peritoneal macrophages.

Recent studies of the antimicrobial capacity of peritoneal macrophages (PM phi) isolated from patients undergoing chronic peritoneal dialysis have raised the question of whether these cells might be analogous to stimulated or activated murine PM phi. To explore this possibility, we compared PM phi from these patients (dialysate-elicited PM phi) with PM phi obtained from women undergoing laparoscopy (resident PM phi) in several in vitro assays of phagocyte function. Although bacterial phagocytosis by cells from both groups of donors was similar, significant differences were found in their chemiluminescence responses to opsonized zymosan. Although the mean peak luminol-enhanced chemiluminescence response of dialysate-elicited PM phi was 4.7 X 10(5) cpm, that of resident PM phi was only 1.3 X 10(5) cpm (P less than 0.05). In a lucigenin-enhanced chemiluminescence assay, dialysate-elicited PM phi again generated significantly greater chemiluminescence than did resident PM phi, suggesting that dialysate-elicited PM phi have a relatively increased capacity for O2- production. Using a fluorochrome microassay to assess the intracellular candidicidal activities of these cells, we found that dialysate-elicited PM phi killed 17% of cell-associated blastospores compared with only 1.5% killing by resident PM phi (P less than 0.05). These investigations led us to conclude that results of studies of the functional activity of dialysate-elicited PM phi cannot necessarily be extrapolated to resident PM phi and that dialysate-elicited PM phi do in some respects behave as stimulated or activated cells.

Bacteria↗

PubMed1985

Protein binding of disopyramide and elevated alpha-1-acid glycoprotein concentrations in serum obtained from dialysis patients and renal transplant recipients.

A rapid ultrafiltration technique was used to measure the free (unbound) fraction of disopyramide in serum obtained from 14 normal volunteers, 6 chronic hemodialysis patients, and 10 renal transplant recipients. The disopyramide-free fraction varied more than tenfold at a corresponding total (free plus bound) serum disopyramide concentration of 3 micrograms/ml and was related to the concentration of an acute-phase protein, alpha-1-acid glycoprotein (AAG), in patient serum. Moreover, disopyramide-free fraction values were nearly twofold lower than normal in serum specimens obtained from those renal patients and transplant recipients with corresponding AAG serum concentrations greater than 100 mg/100 ml. AAG concentrations varied tenfold in patient serum and were on average nearly three times higher than AAG concentrations in normal volunteer serum. These findings suggested that the free fraction of disopyramide and possibly other drugs which bind extensively to AAG may be lower, and the interpatient variability in drug binding may be much more pronounced in serum obtained from hemodialysis patients and transplant recipients than previously recognized.

Adult↗

PubMed1985

Opioid peptides rapidly stimulate superoxide production by human polymorphonuclear leukocytes and macrophages.

Opioid peptides found in the general circulation can modulate several functions of phagocytic cells that are related to their microbicidal and cytotoxic activity. Since reactive oxygen species are crucial to these activities, the affect of opioid peptides on superoxide (O-2) generation was evaluated with the use of lucigenin-enhanced chemiluminesence (CL). beta-Endorphin and dynorphin stimulate the production of O-2 in human polymorphonuclear leukocytes (PMN) and peritoneal macrophages (PMO) at peptide concentrations that prevail systemically (10(-14)-10(-12)M). There is an inverse dose-response relation for PMN but not PMO. The effect is rapid and sustained in PMN (peak CL at 2-4 min, duration greater than 15 min), whereas it is rapid but brief in PMO (peak 1 min, duration less than 3 min). Naloxone inhibits CL responses by greater than 75% in both cell types.

Dynorphins↗

PubMed1985

Glucose-induced increases in renal hemodynamic function. Possible modulation by renal prostaglandins.

Increased glomerular filtration rate and kidney size early in the course of experimental and human diabetes may be important in the pathogenesis of diabetic nephropathy. Factors causing these renal functional changes are unknown. The isolated, perfused rat kidney (IPRK) was used to study the effects of elevated glucose levels on kidneys from normal and diabetic rats in the absence of complex systemic effects of in vivo hyperglycemia. It was found that acute increases in perfusate glucose levels caused sustained dose-dependent vasodilatation in both normal and diabetic isolated kidneys. Furthermore, in normal kidneys, raising perfusate glucose to levels seen in moderately severe diabetes caused increased inulin clearance (Cln). In contrast, equal osmolar concentrations of mannitol caused sustained vasoconstriction and a slight decrease in Cln. Prostaglandin synthetase inhibitors reduced glucose-induced vasodilatation by 50% and prevented the increase in Cln that followed the addition of glucose to normal kidneys. Thus, these studies demonstrated that elevated glucose levels caused significant vasodilatation and increased Cln in the IPRK, and these glucose-induced hemodynamic changes were attenuated by prostaglandin synthetase inhibitors. It is possible that these glucose-induced effects may be important determinants of increased glomerular function in early diabetes.

Animals↗