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Biomedical subjects

R Brenner

Publications and source records attributed to R Brenner.

34 records · Page 2Linked to original sources
PubMed1985

Tricyclic antidepressant and metabolite levels in chronic renal failure.

Serial blood samples were drawn from 12 patients undergoing hemodialysis who were receiving tricyclic antidepressants (TCAs). Samples were drawn before, during, and after a dialysis session (two to 17 sessions per subject). Samples were analyzed by HPLC before and after hydrolysis with beta-glucuronidase/sulfatase to determine the conjugated and nonconjugated metabolites. Analysis of these data in comparison with those of controls with depression and normal renal function showed that: (1) at steady state, tertiary and secondary amine TCA levels did not differ; (2) levels of the hydroxylated metabolites had greater variability and were somewhat higher at steady state; (3) levels of the conjugated hydroxylated compounds were markedly elevated, reaching 500% to 1500% normal; (4) the time to reach a steady-state level appeared to be slightly increased; and (5) elimination t1/2 s of unconjugated and conjugated drug forms were longer in our patients with normal renal function than those reported in the literature. Levels of the tertiary, secondary, and hydroxylated metabolites were not changed by dialysis, whereas there were substantial decrements in glucuronidated metabolite levels. These findings demonstrate increased concentrations of conjugated drug forms and suggest an abnormal distribution or delayed elimination of unconjugated and conjugated metabolites. These observations may shed some light on the apparent hypersensitivity of these patients to TCA side effects, particularly because glucuronides may exert peripheral pharmacologic effects.

Adult↗
PubMed1984

Methylphenidate challenge as a predictor of relapse in schizophrenia.

Although neuroleptics are the major treatment for schizophrenia, there are no effective measures to determine the appropriate or necessary length of neuroleptic maintenance. To test the ability of a psychostimulant challenge to predict relapse following neuroleptic withdrawal, the authors administered methylphenidate and placebo infusions to 11 stable schizophrenic outpatients who had been on a neuroleptic maintenance regimen for at least 6 months. Patients withdrawn from neuroleptics were followed until relapse. All three patients with a positive response to methylphenidate challenge relapsed in 1 to 7 weeks; one of seven negative responders relapsed at week 21. Differences in relapse rates (p = .033) and survival time (p = .005) between negative and positive responders were significant.

Adult↗
PubMed1983

Dexamethasone suppression tests in patients with panic disorder.

Dexamethasone suppression tests were given to 10 patients with panic disorder and 22 depressed patients. All patients with panic disorder were normal suppressors, and nine depressed patients were nonsuppressors. The mean cortisol levels of the two groups differed significantly.

Adult↗
PubMed1981

Isotachophoresis for the determination of oxalate in unprocessed urine.

The principle of isotachophoresis has been used to develop a simple, specific and sensitive analytical procedure for the determination of oxalate in unprocessed urine. Analytical conditions were optimized. The accuracy and precision of the method were estimated. The specificity was checked with oxalate decarboxylase. Separation of oxalate from a number of organic acids was achieved. The influence of factors such as storage, calcium concentration, pH or ionic strength was examined. The 24-h urine excretion rates for healthy children, healthy adults and for patients with idiopathic stone formation were established. Lower absolute excretion rates were found in children and females. Urinary oxalate/creatinine ratios were higher in children than in adults. The mean oxalate excretion in 24-h urines of adult healthy individuals was 413 +/- 150 mumol per 24 h per 1.73 m2 (range 195-732). The mean oxalate/creatinine ratio was 0.033 +/- 0.011 (range 0.018-0.065).

Adult↗
PubMedDate not supplied

[Osteogenesis imperfecta. New viewpoints on principles, clinical aspects and therapy].

Recently osteogenesis imperfecta has attracted much interest both of scientists and clinicians. Modern protein biochemistry and molecular biology have provided evidence that disturbed type I collagen synthesis is involved in the pathogenesis of the disease. Structural defects in the corresponding collagen genes have been identified in some cases, whereas others possibly are due to developmental defects leading to the persistence of a fetal state in collagen biosynthesis. A new clinicogenetic classification of the disease has brought a better understanding of the variable clinical course of the disease. Intramedullary telescopic rodding has proved to be a valuable orthopedic technique for the prevention and correction of fractures and deformities of long bones leading to successful rehabilitation of even severely affected patients.

Collagen↗
PubMedDate not supplied

Serum iron, zinc, copper, selenium, and bromide concentrations after coronary bypass operation.

The effect of surgical trauma on serum trace elements was studied in 10 patients undergoing coronary bypass surgery. After the initial decrease due to the hemodilution during operation serum iron, zinc, copper and selenium remained depressed for the immediate postoperative period. Zinc was still at significantly lower level 2 months after the operation. Low serum iron values were also observed. Changes in trace element concentrations were parallel with changes in the concentrations of their transport and binding proteins in the serum. The multielemental technique also measured nonessential bromide, which returned to initial levels in 7 days. Effects of trauma on metabolism, acute phase reaction with redistribution of zinc and copper and losses via increased urinary excretion explain the above changes. Development of a subclinical deficiency of zinc and possibly iron is suggested by the persistence of low serum levels during recovery after operation.

Aged↗