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Biomedical subjects

R Weil

Publications and source records attributed to R Weil.

At least 37 records · Page 2Linked to original sources
PubMed1978

Role of the renin-angiotensin system in post-transplantation hypertension in patients with multiple kidneys.

To define the role of the renin-angiotensin system in post-transplantation hypertension we studied 12 hypertensive recipients of renal transplants. The patients received saralasin acetate, an angiotensin II antagonist, while on a normal sodium diet and again after seven days of sodium restriction. In six patients with only one kidney, saralasin did not lower blood pressure on either diet; salt depletion did not lower systolic or diastolic blood pressures. In six patients with more than one kidney, salt depletion also did not lower blood pressure; however, salt depletion plus saralasin lowered their systolic pressures from a mean (+/- S.E.M.) of 146 +/- 9 to 128 +/- 8 mm Hg, and mean diastolic pressures fell from 103 +/- 5 to 89 +/- 5 (P less than 0.001). In four of five patients renal-vein renin activity was greater in one or more host kidneys than in the transplant kidney (or kidneys). Although pre-transplant blood pressure was the same in both groups, post-transplantation hypertension is more likely to be angiotensin II-dependent in patients with more than one kidney.

Adolescent↗
PubMed1978

Functional lac carrier protein in cytoplasmic membrane vesicles isolated from Escherichia coli: temperature and pH dependence of dansyl-galactoside binding.

6'-(N-Dansyl)aminohexyl-1-thio-beta-D-galactopyranoside binds specifically to the lac carrier protein in cytoplasmic membrane vesicles isolated from Escherichia coli. Binding can be induced by substrate oxidation (generation of an electrochemical gradient of protons), by potassium efflux in the presence of valinomycin (generation of a potassium diffusion potential), and by passive, carrier-mediated lactose efflux. We show that in all three cases the number of binding sites is temperature dependent. Binding is maximal and constant above 20 degrees ; it decreases between 20 degrees and 10 degrees . Oxidation of substrate (D-lactate) leads to the development of an electrochemical gradient of protons across the membrane (interior negative and alkaline), which is composed of interconvertible electrical and chemical gradients. We show that both the electrical potential across the membrane and the chemical difference in proton concentrations across the membrane are independent of temperature between 5 degrees and 25 degrees . We show that the number of binding sites induced by D-lactate oxidation depends on pH. At both 25 degrees and 5 degrees , the number of binding sites increases from pH 5 to pH 6.5, remains constant between pH 6.5 and 7, and decreases from pH 7 to pH 8. In contrast, the number of binding sites induced by passive, carrier-mediated lactose efflux is independent of pH between pH 5.5 and pH 8. From these findings, we conclude that the pH- and temperature-dependent effects on the number of 6'-(N-dansyl)aminohexyl-1-beta-thio-D-galactopyranoside binding sites have different origins. The pH dependence of binding is energy linked and reflects in part the pH dependence of the electrochemical gradient of protons across the membrane generated by substrate oxidation. The temperature dependence is not an energy-linked phenomenon. The decrease of the number of binding sites at low temperature probably reflects the aggregation of the lac carrier protein with other membrane proteins. This aggregation takes place as a consequence of the conformational disorder-to-order transition of the membrane lipids and the concomitant preferential segregation of the lac carrier protein in the membrane domains containing the disordered lipids.

Carrier Proteins↗
PubMed1978

Colon perforation after kidney transplantation.

Between 1962 and 1977 approximately 2% of Denver kidney transplant patients developed colon perforation. The single commonest cause was diverticulitis of the left colon (6/13 cases). In spite of drastic reduction or discontinuation of immunosuppression, only 5/13 patients survived for more than 90 days after operation. Analysis of this experience suggests that the high mortality rate associated with this complication can be reduced by early operation which removes the perforation from the peritoneal cavity (either exteriorization or resection) without primary intestinal reanastomosis. We believe that candidates for kidney transplantation with a history of previously symptomatic diverticulosis coli should have elective colon resection prior to transplantation. Any kidney transplant patient with lower abdominal signs should be investigated and treated aggressively.

Adolescent↗
PubMed1978

Optimal technique of renal arteriography in living renal transplant donors.

Sixty consecutive living related renal donors were evaluated retrospectively with regard to the adequacy of their preoperative angiograms. Comparison of the original radiologic reports and the surgical findings revealed no errors in the prediction of the number and length of renal arteries of the transplanted kidneys. The optimal arteriographic technique is defined in the context of the information required by the surgeon: it is concluded that selective renal arteriography, although often advocated, is seldom necessary if the standard anteroposterior view of the abdominal aortic injection is supplemented by oblique and occasionally other views in selected cases.

Adolescent↗
PubMed1978

Pediatric cadaver kidneys for transplantation.

A group of 24 kidneys from donors ranging in age from 1 1/2 to 10 years were transplanted singly into adults and were compared to a group of 44 adult cadaveric kidneys transplanted into adults. There were no vascular complications in either group. There were two urological complications in the 24 pediatric donor cases and none with the adult donor cases. During the first month after transplantation, the mean creatinine clearance was lower in the pediatric donor group; later the function of the pediatric donor kidneys was at least as good as the function of the adult donor grafts. In the group of pediatric donor kidneys, the outcome using kidneys from donors younger than 3 years of age was less satisfactory than for donors 3 to 10 years of age. These data suggest that transplantation of a single pediatric kidney into an adult, particularly if the pediatric donor is at least 3 years of age, will provide satisfactory renal function.

Adult↗
PubMed1977

Acute bacteremia in asplenic renal transplant patients.

Four cases of overwhelming bacteremia were observed in asplenic renal transplant patients 12 to 20 months after transplantation. The bacteriologic findings and presentation of these infections are characteristic of post-splenectomy sepsis reported in nontransplant patients. It is suggested that the absence of the spleen, more than immunosuppression with azathioprine and prednisone, predisposes to these late, uncommon infections after transplantation.

Acute Disease↗
PubMed1977

Listeria monocytogenes infection after renal transplantation.

Listeria monocytogenes infection has been observed in 13 patients, of a group of more than 700 renal transplants, treated during the past 13 1/2 years. The infection usually was manifested as bacteremia or meningitis. Twelve of the 13 patients survived the infection; one died of brain-stem herniation due to increased intracranial pressure. The recommended treatment is intravenously given ampicillin sodium.

Adult↗
PubMed1977

Pediatric kidney transplantation for cystinosis.

In an experience of more than 700 kidney transplants, three recipients are known to have had congenital cystinosis. A cadaver kidney transplant in a 10 yr old child with nephropathic cystinosis functioned well for 7 1/2 yr before it was rejected and the graft was free of recurrent cystinosis after that interval. This prolongation of life was associated with marked accumulation of cystine in the patient's thyroid gland, presenting as a mass in the neck. If additional longevity is achieved in this patient, abnormal intracellular cystine accumulation may be expected in other host tissues. Retransplantation was carried out with the father as donor, accepting the possibility of increased cystine levels in the retransplant. This patient's age of 18 yr identifies him as one of the longest known survivors of infantile nephropathic cystinosis.

Adolescent↗
PubMed1977

Microenvironment of the binding site in the lac carrier protein.

Studies with a homologous series of (N-dansyl)aminoalkyl-1-thio-beta-D-galactopyranosides containing two to six methylene carbons bridging the galactosyl and dansyl ends of the molecules are described. The compounds were utilized in radioactive and nonradioactive form, and binding of each homologue to membrane vesicles isolated from Escherichia coli ML 308-225 was measured directly by flow dialysis in the presence of D-lactate. The results are compared with the D-lactate-induced fluorescence enhancement observed with each dansylgalactoside and with the ability of N-methylpicolinium perchlorate to quench the fluorescence of the bound homologues. The binding affinity of the lac carrier protein for the probes varies directly with the length of the alkyl linkage, and the same number of binding sites is observed with each homologue. In contrast, however, the increase in fluorescence observed upon binding varies dramatically as the alkyl chain is increased in length, with the fluorescence exhibiting maximal values at two and six methylene carbons and a minimum at four methylene carbons. Furthermore, quenching by N-methylpicolinium perchlorate exhibits an inverse relationship and maximum quenching is observed with the 4 carbon homologue. Possible reasons for this behavior are discussed.

Bacterial Proteins↗
PubMed1977

Polyoma-induced stimulation of cellular RNA synthesis is paralleled by changed expression of the viral genome.

We studied synthesis of viral and cellular RNA in the presence and absence of 5-fluorodeoxyuridine (FdU, an inhibitor of DNA synthesis) during lytic infection with polyoma virus in confluent, primary mouse kidney cell cultures. In the presence of FdU, synthesis of early 19S polyoma mRNA and of polyoma tumor (T)-antigen, i.e. expression of the early viral gene, is rapidly followed by a mitogenic reaction of the host cell; it leads to an increase of 30 +/- 5% in cellular, mainly 28S and 18S rRNA, followed by activation of the cellular DNA-synthesizing apparatus. Polyoma-induced cellular RNA synthesis is paralleled by increased production of early 19S mRNA and begin of expression of the late viral genes, leading to synthesis of small amounts of late 19S and 16S mRNAs. Changed expression of the viral genome occurs in the absence of detectable synthesis of polyoma DNA I. Infection in the absence of FdU induces the same sequence of events; it is followed, however, by duplication of the mouse cell chromatin (S-phase) and production of progeny virus.

Cell Line↗
PubMed1977

Urine plasmin-like substances as an index of kidney allograft rejections.

Using solid state radioimmunoassays developed by the first author, changes in the urine level of plasmin-like substances (PLS) and fibrin degradation products (FDP) before and after human kidney transplantation were determined in 49 transplant patients. Averages of urine PLS and FDP in a normal population of 51 persons were 0.13+/-0.10 (SD) and 0.14+/-0.07 microng/ml, respectively. In all transplant patients there was an initial rise of both PLS and FDP in urine immediately after transplantation. This elevation peaked on days 4 and 5 and the PLS and FDP levels returned to normal range within 2 weeks in patients without evidence of rejeciton. A secondary rise of urine PLS was detected before or with a rise in serum creatinine in all of the patients experiencing rejections. Of 11 patients who showed a rejection episode within 2 weeks of transplantation, the secondary rise of urine PLS was detectable in 55% of the patients slightly before the serum creatinine level changes; of 6 patients with a rejection episode more than 2 weeks after transplantation, 100% showed a secondary PLS rise 6.7+/-2.3 (SE) days before the serum creatinine increased. The appearance of the secondary rise of urine FDP in the rejecting recipients was slightly later than the rise of PLS. Serial determination of urine PLS levels following human kidney transplantation appears to be an early index of rejections which occurs more than 2 weeks after transplantation, although the clinical usefulness of this measurement is probably limited.

Creatinine↗