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Biomedical subjects

R Pollak

Publications and source records attributed to R Pollak.

At least 55 records · Page 3Linked to original sources
PubMed1995

Reduced inter- and intrasubject variability in cyclosporine pharmacokinetics in renal transplant recipients treated with a microemulsion formulation in conjunction with fasting, low-fat meals, or high-fat meals.

This cross-over study compared the pharmacokinetic parameters obtained from cyclosporine (CsA) concentration-time profiles after administration of the corn oil-based soft gel cap (CsA-GC) with those with the microemulsion (CsA-ME) gel cap. Neither the fasting state nor the coadministration of a low- or high-fat breakfast affected the pharmacokinetics of CsA presented in either formulation. Comparisons of the three sets of pharmacokinetic parameters--namely, after fasting or after low-fat or after high-fat diets--demonstrated the CsA-ME formulation to display greater intraindividual reproducibility of the C0 and C12 trough levels (TLs), Cmax, tmax, and area under the concentration-time curve (AUC) than the CsA-GC formulation. Although the degree of interindividual variation in AUC, Cmax and tmax after CsA-ME administration was slightly, but significantly, less than after CsA-GC administration, there was no difference between the two formulations in terms of the customarily monitored C0 or C12 TL values. CsA-ME showed higher correlation coefficients of drug exposure (AUC) with C12 than CsA-GC (0.910 versus 0.712). However, CsA-ME administration resulted in only modest improvement over CsA-GC administration in the relationships between drug dose and C0, C12, or AUC--namely, 0.645 versus 0.496, 0.611 versus 0.517, and 0.700 versus 0.501, respectively. Correlation analysis between individual timed samples and AUC determinations revealed that CsA-ME requires significantly less frequent blood monitoring for prediction of total drug exposure than does CsA-GC. Although the clinical utility of this reproducible pharmacokinetic behavior remains to be demonstrated in the de novo transplant setting, the markedly reduced intraindividual variation produced by administration of CsA-ME will likely improve the accuracy of pretransplant prediction of, and reduce the frequency of subsequent adjustments in, CsA doses.

Corn Oil↗
PubMed1994

Hepatitis C infection in potential recipients with normal liver biochemistry does not preclude renal transplantation.

The hepatitis C virus (HCV) may be an important cause of chronic liver disease in renal transplant recipients. We investigated retrospectively the incidence and outcome of HCV infection in long-term renal transplant recipients and patients on hemodialysis. Stored, pretransplant sera of transplant recipients with normal liver biochemistry at surgery were tested for hepatitis C by a second-generation enzyme immunoassay. Hemodialysis patients were tested by a first-generation enzyme-linked immunosorbent assay (ELISA) against c100-3. We studied 252 renal transplant recipients and 58 hemodialysis patients followed for 65 +/- 10 months and 26 +/- 6 months, respectively. Fifteen percent (38/252) of the transplant recipients were HCV positive as were 3/58 (5%) of the hemodialysis patients. Overt liver disease occurred in 22/252 (8.7%) transplant recipients and none in the hemodialysis group. Thirty-six percent (8/22) of transplant recipients with overt liver disease were HCV positive. No HCV-positive patients died of liver failure. Of six biopsies in the HCV-positive transplant group, two had histological evidence of CAH. CAH was seen in six of eight biopsies in the HCV-negative transplants and two of these latter patients progressed to cirrhosis. No hemodialysis patients had clinical or histological evidence of chronic liver disease. Two HCV-negative transplant patients died of liver failure, while no deaths related to liver disease occurred in hemodialysis patients regardless of HCV status. We conclude that hepatitis C may cause chronic hepatitis in renal transplant patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Effects of steroid withdrawal on long-term renal allograft recipients with posttransplantation diabetes mellitus.

BACKGROUND: Posttransplantation diabetes mellitus (PTDM), a common complication of current immunosuppressive regimens, has been attributed to the diabetogenic effects of prednisone and cyclosporine. We report our experience with steroid withdrawal (SW) in renal allograft recipients with PTDM. METHODS: SW was attempted on 12 selected renal allograft recipients with PTDM, and its effects on various clinical parameters were recorded before and more than 3 months after SW. RESULTS: Patient and graft survival was 100%, and all patients had a stable serum creatinine level and remained steroid free 15.4 +/- 5 months after SW. Ten patients had a significant improvement in their diabetic management. Glycosylated hemoglobin decreased from 13.6% +/- 2.3% to 9.2% +/- 2.9% (p = 0.0002); body weight decreased from 92 +/- 21 kg to 86 +/- 21 kg (p = 0.0134), and management of hypertension improved in eight of nine (89%) recipients with hypertension. The total cholesterol level decreased from 253 +/- 57 mg/dl to 208 +/- 40 mg/dl (p = 0.0041), but the high-density lipoprotein cholesterol also decreased from 46 +/- 8.9 mg/dl to 39.7 +/- 10.9 mg/dl (p = 0.073), so that the total cholesterol/high-density lipoprotein ratio was not significantly affected (p = 0.775). CONCLUSIONS: SW in selected, stable, long-term renal allograft recipients with PTDM has a favorable effect on glucose homeostasis, body weight, and management of hypertension; its effect on lipid metabolism and subsequent cardiovascular risk factors warrant further study.

Adrenal Cortex Hormones↗
PubMed1993

Clinically significant hearing loss in renal allograft recipients treated with intravenous erythromycin.

BACKGROUND: Hearing loss is generally regarded as a rare side effect of erythromycin therapy. However, our own clinical experiences in erythromycin-treated patients led us to suspect that this complication may be more common among renal allograft recipients. The purpose of this study was to evaluate the incidence, predisposing factors, clinical characteristics, and outcomes of erythromycin-induced hearing loss among renal allograft recipients. METHODS: We reviewed medical records of renal transplant patients treated for pneumonia with intravenous erythromycin lactobionate. Patients were evaluated for the occurrence of clinically significant hearing loss (including onset, duration, and reversibility), other signs and symptoms of ototoxicity (vertigo and tinnitus), daily erythromycin dose and duration of treatment, concurrent ototoxic drug therapy, renal and hepatic function, and history of previous otic disease. RESULTS: Eleven (32%) of 34 courses of intravenous erythromycin therapy resulted in hearing loss. The incidence of hearing loss was 53% (eight of 15 courses) in patients treated with 4 g of erythromycin daily compared with 16% (three of 19 courses) among those receiving 2 g/d (P = .05). In addition, courses of erythromycin were longer in those suffering auditory toxicity (9.6 +/- 4.7 days) than in nontoxic patients (5.7 +/- 3.6 days) (P < .05). Hepatic and renal function did not differ between toxic and nontoxic patients. All episodes of erythromycin-induced hearing loss were reversible. CONCLUSIONS: We conclude that clinically significant hearing loss occurs in more than 30% of renal allograft recipients treated for pneumonia with intravenous erythromycin lactobionate. Patients who require prolonged courses of erythromycin and those treated with 4 g/d are at particular risk for the development of auditory toxicity. With prompt recognition and modification of therapy, erythromycin-induced hearing loss appears to be completely reversible.

Adult↗
PubMed1993

A study of treatment compliance following kidney transplantation.

Kidney transplantation is a successful treatment for end-stage renal disease. We studied demographic and psychosocial variables that relate to compliance behaviors following renal transplant. One hundred and five renal allograft recipients, with a minimum of 18 months follow-up, were studied. A biographical questionnaire, the Center for Epidemiologic Studies Depression Scale, the Multidimensional Health Locus of Control Scale, and the Social Support Appraisals Questionnaire were used as measuring instruments. Specifically for this study, we designed a Health Belief Model Questionnaire, a Patient and Provider Relationship Questionnaire, a Compliance Self-Report Questionnaire, and a Self-Efficacy Questionnaire. Compliance was determined by cyclosporine whole blood levels > 30 ng/ml, maintenance of ideal body weight (< 20% gain), and percentage of missed clinic visits (< 20%). Data was analyzed using discriminant analysis, Pearson's correlation, and chi-square. Four groups were identified, i.e., overall compliant (n = 25), noncompliant with diet (n = 29), noncompliant with medication (n = 27), and overall noncompliant (n = 29). No patient missed > 20% of clinic visits. Discriminant function analysis distinguished patients who were compliant from those who were not. Males were more likely to be noncompliant with medication, whereas females were more likely to be noncompliant with diet. Noncompliance was also associated with increased numbers of prescribed medications, depression, black race, locus of control attributed to powerful others, unemployment, as well as the perceived amount of social and family support. Patients with failed grafts (n = 14) were more depressed (P < 0.05), perceived less benefit from the treatment regimen (P < 0.01), and had less confidence in their care providers (P < 0.05) than those recipients of successful grafts (n = 91). In conclusion, this study identifies a number of psychosocial and demographic variables that impact on patient compliance behaviors after renal transplant. Interventional strategies to obviate noncompliance will need to consider these heterogeneous variables in order to maximize long-term renal allograft survival.

Adult↗
PubMed1993

A randomized double-blind trial of the use of human recombinant superoxide dismutase in renal transplantation.

Oxygen free radical generation has been implicated as a possible mediator of the reperfusion injury postulated to occur following revascularization of the cold preserved and transplanted kidney. The superoxide radical (O2-) scavenger, superoxide dismutase, from bovine or recombinant (rh-SOD) sources, may ameliorate oxygen-free-radical mediated reperfusion injury of transplanted kidneys. To test this hypothesis, we performed a prospective, randomized, double-blind trial of the use of human rh-SOD in renal transplantation at three participating centers. Half of a 20 mg/kg solution of rh-SOD or placebo was administered as a bolus intravenous injection immediately prior to renal allograft reperfusion and the remainder as a peripheral intravenous infusion for 1 hr thereafter. Posttransplant renal function was determined using 99Tc-DTPA clearance to measure glomerular filtration rate at 48 +/- 24 hr and day 6 post-transplant. A two-tailed t test was used for pooled data, and analysis of variance was used to evaluate between center differences in outcome. One hundred and sixteen patients (58 rh-SOD and 58 placebo) were entered into the study. No adverse reactions to rh-SOD or placebo were noted. No differences were noted between rh-SOD and placebo groups with regard to GFR at 48 hr, serum creatinine or creatinine clearance at day 6, or percentage of patients with GFR < or = 10 ml/min or < or = 5 ml/min at 48 hr. The data did not vary when analyzed by center or in aggregate form, and no correlation was noted between storage time and GFR in either group. We conclude that data from this trial provide little basis for the use of rh-SOD as described to ameliorate reperfusion injury in transplanted kidneys.

Adult↗
PubMed1993

The morphology and function of rabbit hepatocytes isolated using ethylenediaminetetraacetate.

The enzyme digestion technique using collagenase is used in most studies that describe hepatocyte isolation, including those in which hepatocytes are isolated for transplantation. The use of collagenase, however, has several drawbacks. We describe the use of a highly concentrated ethylenediaminetetraacetate solution for isolation of hepatocytes followed by purification using a Percoll gradient in the rabbit model. Isolated hepatocytes were then preserved at 4 degrees C for up to three days in either University of Wisconsin solution or Dulbecco's modified eagle's medium. Morphological studies of hepatocytes at 24 hr and 72 hr in either medium were performed using Papanicolaou and PAS stains of cytopreparations for the presence of glycogen. Similarly, functional studies of the preserved hepatocytes included LDH release, total tissue water content, and amount of 99m-technetium mebrofenin uptake. The use of EDTA perfusion for hepatocyte isolation was highly reproducible in this model. The cell yield was comparable to that achieved previously using collagenase. The morphologic studies demonstrated pure hepatocytes with well-preserved architecture when preserved for up to three days in UW solution. Functional studies showed a statistically significant lower LDH release and total tissue water content and a higher technetium-99m mebrofenin uptake for hepatocytes preserved in UW solution. We conclude that a pure and viable hepatocyte suspension can be obtained from rabbit livers using concentrated EDTA solutions. These hepatocytes can be well preserved at 4 degrees C for up to 72 hr in UW solution, based on morphologic and functional criteria.

Adenosine↗