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Biomedical subjects

D Ross

Publications and source records attributed to D Ross.

At least 235 records · Page 13Linked to original sources
PubMed1989

Desferrioxamine therapy in hemodialysis patients with aluminum-associated bone disease.

Aluminum toxicity in dialysis patients is associated with decreased bone turnover and a relative parathyroid hormone (PTH) deficiency. Desferrioxamine (DFO), a chelating agent, has been reported to improve bone histology in aluminum associated, low turnover bone disease in dialysis patients not subjected to parathyroidectomy. Information on the effect of DFO therapy on parathyroid gland function is lacking. In the present study, in addition to changes in bone histology, parathyroid gland function was evaluated in 18 hemodialysis patients with aluminum associated, low turnover bone disease (osteomalacia and aplastic bone disease) before and after one year of DFO treatment (1 to 6 g/week). Parathyroid gland function was assessed by using a calcium free and high calcium (3.5 to 4 mEq/liter) hemodialysis bath.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum↗
PubMed1989

Prospective, controlled, randomized trial of naloxone infusion in early hyperdynamic septic shock.

To determine whether naloxone infusion is efficacious in severe hyperdynamic septic shock, we conducted a prospective study of 22 patients randomly assigned to a naloxone or placebo group. Patients were treated 12 +/- 2 h (SEM) after the onset of shock, with a mean arterial pressure (MAP) of 63 +/- 3 mm Hg. All patients had clinical evidence of an infectious process and required dopamine 20 +/- 2 micrograms/kg.min. Five (46%) of 11 patients in the naloxone group and one (9%) of the other 11 patients in the placebo group responded clinically. The MAP among the five responders increased from 62 +/- 5 to 89 +/- 4 mm Hg within 20 min of naloxone treatment (p less than .01). This favorable hemodynamic response was sustained throughout the patients' clinical course. In contrast, the MAP did not change significantly in the nonresponders who received naloxone, nor did it change in the placebo group. More patients in the naloxone group than in the placebo group received steroids concurrently. Survival rate was 100% in those who responded to naloxone clinically. However, overall survival rate in each group was essentially the same. No adverse effects were observed, except for mild agitation in some of the patients receiving naloxone. We conclude that naloxone infusion is clinically efficacious in improving the hemodynamic profile of a subgroup of patients with severe early hyperdynamic septic shock, but does not appear to improve the overall survival rate.

Aged↗
PubMed1989

In vitro and in vivo evaluation of platelet concentrates after cotton wool filtration.

Removal of leukocytes from platelet concentrates (PC) may decrease the incidence of alloimmunization to HLA antigens on white cells and prevent or delay refractoriness. Cotton wool filtration, which effectively removes leukocytes from PC with minimal platelet loss, may cause platelet or complement activation. In this study, the effect of cotton wool filtration (Imugard IG-500) on platelet activation, in vitro function, posttransfusion survival, and complement activation was investigated. Five paired autologous in vivo percent recovery and survival studies were performed with fresh (6-8h) PC or with 5-day-stored PC prepared from CPD-anticoagulated blood and stored in PL-732(TM) containers using standard methods. In the paired design, PC from the same donor were filtered on one occasion, and not filtered on another, prior to labeling with indium-III-oxine and reinfusion. Percent recovery and survival were then determined by the standardized method. Filtration had no statistically significant effect on percent recovery on PC stored for 6-8h or for 5 days. There was, however, a slight decrease in survival hours of the filtered PC which was statistically significant at 6-8h (203 +/- 14 vs. 179 +/- 18h; p less than 0.05) but not at 5 days (166 +/- 28 vs. 132 +/- 27h; p greater than 0.05). Samples taken before and after filtration of single units (fresh and 5-day) and pooled units (3-day) for measurement of release of granular content (beta-thromboglobulin), lysis (LDH), and in vitro viability - ATP, extent of shape change with ADP, and hypotonic shock response (3-day only)-demonstrated no effect of filtration on these parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Coronary risk factor outcomes following coronary artery bypass surgery.

The coronary risk factor status of patients prior to and following coronary artery bypass surgery (CABG) has been poorly investigated. Two consecutive series of CABG patients were surveyed following CABG. One hundred and thirty patients were assessed immediately following CABG and 530 patients were assessed 12-30 months following CABG. For the long-term post-CABG group, over 80% of those who had ever smoked had ceased. Sixty-four per cent of these males and 50% of females were classified as being overweight. Twenty-five per cent of males and 34% of females reportedly had high serum cholesterol (i.e. greater than or equal to 6.5 mmol/L). Comparing these CABG data with age-adjusted National Heart Foundation Risk Factor Prevalence Survey data, there was a higher prevalence of ex-smokers, overweight, hypertension, and elevated cholesterol. It was concluded that on most coronary risk factors, except for smoking, these CABG patients had a worse profile than the general Australian community. This problem warrants further research and the development of appropriate treatment programs.

Adult↗
PubMed1989

National community health worker programs: how can they be strengthened?

This article is based on a collaborative research study of policy and practice in national community health worker (CHW) programs in developing countries. The study involved a review of the relevant literature, case studies in Botswana, Colombia and Sri Lanka, and an international workshop where the future of such programs was discussed. The findings of this research are discussed under four headings: unrealistic expectations, poor initial planning, problems of sustainability, and the difficulties of maintaining quality. It is clear that existing national community health worker programs have suffered from conceptual and implementation problems. However, given the interest and political will, governments can address these problems by adopting more flexible approaches within their CHW programs, by planning for them within the context of all health sector activities rather than as a separate activity, and by immediately addressing weaknesses in task allocation, training and supervision. CHWs represent an important health resource, whose potential in extending coverage and providing a reasonable level of care to otherwise underserved populations must be fully tapped.

Botswana↗
PubMed1988

Bioactivation of catechol in rat and human bone marrow cells.

o-Benzoquinone-glutathione (GSH) conjugate formation and covalent binding of [14C]catechol to protein were utilized as probes of bioactivation of catechol in both rat and human white bone marrow cell systems. Conjugate formation and binding occurred in the absence of exogenous hydrogen peroxide, but were markedly stimulated by its addition. Protein-binding and conjugate formation using rat cells in the presence of exogenous peroxide were increased by the presence of phenol whereas GSH and hydroquinone inhibited binding. Similarly, protein-binding in the absence of exogenous peroxide was inhibited by GSH and exacerbated by phenol. Prostaglandin synthase, the peroxidatic function of which may also utilize hydrogen peroxide as a substrate, appeared on the basis of experiments using arachidonic acid to play only a minor role in bioactivation of catechol in rat bone marrow cells. These results show that peroxide-dependent bioactivation of catechol occurs in rat and human bone marrow cells and that hydroquinone and GSH inhibit whereas phenol stimulates bioactivation.

Animals↗
PubMed1988

Oxidation of catechol by horseradish peroxidase and human leukocyte peroxidase: reactions of o-benzoquinone and o-benzosemiquinone.

The metabolism of secondary phenolic metabolites of benzene, such as catechol, by peroxidases represents one possible mechanism underlying benzene-induced myelotoxicity. The oxidation of catechol by horseradish peroxidase and peroxidases present in human leukocytes was therefore examined. Peroxidatic oxidation resulted in o-benzoquinone production, which was characterized as its bromothiophenol adduct. o-Benzoquinone-glutathione conjugates were formed during peroxidatic oxidation of catechol in the presence of glutathione. Both mono- and diglutathione conjugates were detected. As much as 80% of catechol removed during peroxidatic oxidation could be recovered as glutathione conjugates of o-benzoquinone. Glutathione had no inhibitory effect on the removal of catechol during peroxidatic oxidation. In the presence of divalent cations (Mg2+, Zn2+), however, which slow the rate of o-semiquinone disproportionation, glutathione was found to inhibit catechol removal. This suggests that in the absence of stabilizing metal, reduction of the o-benzosemiquinone radical by glutathione cannot compete with other rapid reactions of the radical such as disproportionation. No interaction of the o-benzosemiquinone radical with oxygen could be detected even in the presence of stabilizing metals or superoxide dismutase which inhibits the reverse reaction of the SQ + O2 in equilibrium Q + O.2 equilibrium. Thus, under physiological conditions, glutathione and oxygen would not be expected to reduce or oxidize respectively the o-benzosemiquinone radical. These data show that the generation of thiol conjugates of o-benzoquinone can be used as probes of peroxidatic oxidation of catechol.

Benzoquinones↗
PubMed1988

Heterotopic prosthetic ventricles as a bridge to cardiac transplantation. A multicenter study in 29 patients.

Heterotopic prosthetic ventricles were used to support the circulation in 29 candidates for heart transplantation who were expected to die before procurement of a donor heart. Twenty-one of these patients (average age, 36 years) underwent successful transplantation after 8 hours to 31 days of circulatory support. The other eight patients died because their condition could not be stabilized for transplantation, despite restoration of blood flow. Fourteen patients received biventricular support; 15 received only left ventricular support, with pharmacologic assistance of right heart function. Before transplantation, blood flow from the left prosthetic ventricle averaged 2.8 +/- 0.4 liters per minute per square meter of body-surface area, and from the right prosthesis 2.4 +/- 0.4 liters, as compared with an average flow of 1.6 +/- 0.5 liters per minute per square meter before implantation. Of the 21 patients who received heart transplants, 20 were discharged from the hospital after a median of 31 days. Nineteen patients were alive at 7 to 39 months, and 11 of the first 12 were alive at one year. We conclude that heterotopic placement of prosthetic ventricles as a bridge to transplantation provides an effective method of temporarily supporting cardiac function in critically ill patients without removing the natural heart. The early survival rate after transplantation is similar to that with elective cardiac transplantation.

Adolescent↗
PubMed1988

Sex and strain differences in the hepatotoxic response to acute cocaine administration in the mouse.

Cocaine-induced hepatotoxicity was examined in vivo in a dose-responsive manner in C57BL/6Ibg, DBA/2Ibg, C3H/2Ibg, and Balb/cJ mice. Serum glutamic-pyruvic transaminase (SGPT) activities were determined 24 hours after intraperitoneal (IP) administration of cocaine (20 to 100 mg/kg). Significant elevations (100- to 150-fold) in SGPT were observed in male mice receiving cocaine. Significant differences in sensitivity to cocaine-induced hepatotoxicity were found among males of the inbred strains, with Balb being most sensitive and C57BL being least sensitive and C3H and DBA strains exhibiting intermediate sensitivity. Female mice of the four inbred strains were more resistant than males to cocaine-mediated hepatotoxicity, as indicated by only twofold to tenfold elevations in SGPT values. Among the females, sensitivity of the four inbred strains--as indicated by dose response curves--fell into two categories: the sensitive strains (C3H and C57BL) and the resistant strains (Balb and DBA). Pretreatment of males of the four inbred strains with the P-450 inducer phenobarbital resulted in enhancement of cocaine-mediated hepatotoxicity in the C57BL and Balb but not the C3H and DBA mice. Phenobarbital pretreatment of females of the four inbred strains resulted in enhancement of the hepatotoxic response to cocaine in the C3H, DBA, and Balb mice. Phenobarbital-pretreated C57BL females exhibited a 100% mortality rate after the acute cocaine dose, and thus no determination of hepatotoxicity could be established for them. These data demonstrate sex and strain differences in cocaine-induced hepatotoxicity and suggest that phenobarbital pretreatment does not uniformly enhance the hepatotoxicity of cocaine.

Alanine Transaminase↗
PubMed1988

Cocaine-induced biochemical changes and cytotoxicity in hepatocytes isolated from both mice and rats.

The mechanism of cocaine-induced cytotoxicity was investigated in hepatocytes isolated from both male C3H mice and male Sprague-Dawley rats. Cocaine was more cytotoxic to mouse hepatocytes than rat and induced reduced glutathione (GSH) depletion prior to marked increases in cytotoxicity in both systems. In both mouse and rat cells, GSH depletion was accompanied by GSSG production, but in rat cells, quantitative measures suggested that other mechanisms contributed to GSH depletion. No cocaine-induced depletion of protein-thiol groups or generation of protein-glutathione mixed disulfides could be detected in rat cells. Cocaine induced lipid peroxidation, using malondialdehyde (MDA) production as an index of the peroxidation process, in both mouse and rat hepatocytes. Inhibition of MDA production to below control levels using the antioxidant N,N'-diphenyl-phenylene diamine (DPPD) however, had no inhibitory effect on cocaine-induced cytotoxicity in either mouse or rat cells. These data suggest that neither generalized protein thiol depletion nor lipid peroxidation are critical determinants of cocaine-induced cytotoxicity in cellular systems.

Animals↗
PubMed1988

Butylated hydroxytoluene (BHT)-mediated increases in NAD(P)H-quinone oxidoreductase (QR) in mouse lung: evidence for the alveolar type II cell as a site of QR activity.

Administration of butylated hydroxytoluene (BHT) to inbred A/J mice increased lung cytosolic NAD(P)H-quinone oxidoreductase (QR) activity. Increased QR activity was observed using a dose of BHT of 100 mg/kg ip, although maximal increases in activity were observed following BHT 300 mg/kg ip. Increased lung QR activity could be observed as early as 24 hr post-BHT (300 mg/kg ip). Bronchiolar Clara cells and pulmonary macrophages isolated using an elastase digestion procedure from both control and BHT-treated mice exhibited minimal QR activity. The majority of basal and BHT-increased QR activity remained in the undigested lung. As isolation of many cell types to a high degree of purity from mouse lung is not yet feasible, QR activity was measured in established mouse lung cell lines and in cell isolates from rat lung. QR activity was low in a Clara tumor cell line, but higher activity was observed in three alveolar type II cell lines. Type II cell-enriched populations isolated from rat lung exhibited sixfold greater QR activity than the remaining undigested lung. Pulmonary QR activity was significantly greater in rat than in A/J or C57 mice. Treatment of cultured Clara or type II cells with BHT in vitro did not increase QR activity.

Animals↗
PubMed1988

Regional and subcellular distribution of [3H]nitrendipine binding sites in SHR and WKY rats.

Differences in [3H]nitrendipine binding sites in brain regions and subcellular fractions from cortex have been investigated in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. At 4 weeks of age, [3H]nitrendipine receptor binding (Bmax) was increased in the hypothalamus and striatum of SHR but not WKY rats, whereas no changes were found in the cortex, cerebellum, or brain stem. At 12 weeks of age, [3H]nitrendipine binding (Bmax) was still elevated in the hypothalamus of SHR, whereas binding in the striatum was not significantly different. [3H]Nitrendipine binding in SPM-1 membrane from cortex was elevated at 12 weeks of age, whereas no changes were seen in nuclear, mitochondrial microsomal, or SPM-3. These results demonstrate that prior to elevated blood pressure, [3H]nitrendipine receptor binding is increased in discrete brain regions and membrane fractions and suggest that "L" type calcium channels may be under genetic control and be involved in development of hypertension.

Animals↗
PubMed1988

Pulmonary valve autotransplantation (the Ross operation).

In 1967, homografts had been in place five years and the early nonviable and natant freeze-dried valves were showing irrefutable signs of degeneration and calcification. For this reason, in 1967, we moved to reserving both viability and tissue integrity by cryopreservation. To overcome the problems of procurement, the next logical step was to transfer the patient's own pulmonic valve to the aortic area. In the past twenty years, 249 operations have been performed. Of the 249 patients, there have been 16 operative deaths (6.5%), but no operative deaths in the past ten years. There have been no details related to primary tissue failure in the aortic area. There have been 36 reoperations (14.4%).

Aortic Valve↗
PubMed1988

The influence of dose, beverage type, and sex of interactor on female bar patrons' verbal aggression.

This field study is an investigation of the influence of dose, type of beverage, and the sex of the confederate on female verbal aggression. The results showed no consistent effects attributable to dose; drinking liquor resulted in less aggressive responses but only when subjects interacted with a female confederate. The results show that studies of alcohol and aggression that use only male subjects do not generalize to females in natural settings and suggest that nonpharmacological factors need more attention in this area.

Adolescent↗