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Biomedical subjects

D Roth

Publications and source records attributed to D Roth.

At least 109 records · Page 6Linked to original sources
PubMed1995

Hepatitis C virus: the nephrologist's view.

The last 4 years have been a period of rapid expansion in our understanding of both the molecular biology and clinical significance of hepatitis C virus (HCV) infection. Initial studies using first-generation enzyme-linked immunosorbent assays suggested that the end-stage renal disease population had an exceptionally high prevalence of anti-HCV compared with asymptomatic healthy blood donors. Subsequent analyses with second-generation assays and polymerase chain reaction techniques to detect viremia confirmed these earlier studies. Considering the prevalence of HCV within the dialysis population, it comes as no surprise that several studies confirmed HCV as the leading cause of non-A, non-B hepatitis among renal allograft recipients. Furthermore, transmission of HCV by transplantation of a kidney from an HCV-infected organ donor has been unequivocally demonstrated. The natural history of HCV infection in the immunosuppressed allograft recipient and its impact on long-term patient outcome are still being analyzed. Finally, HCV has been associated with essential mixed cryoglobulinemia and several histologic patterns of immune complex glomerulonephritis, including membranous and membrano-proliferative glomerulonephritis. Although HCV antigen-antibody complexes have not been demonstrated in the kidney, the marked decrease in proteinuria following clearance of HCV RNA with interferon alpha-2b therapy suggests an etiologic role for HCV in these glomerular diseases. Furthermore, the demonstration of HCV RNA in the cryoprecipitate of patients with essential mixed cryoglobulinemia and a beneficial response to treatment with interferon alpha-2b also suggest a role for HCV in the pathogenesis of these clinical syndromes.

Cryoglobulinemia↗
PubMed1995

Distinct effects of alpha-SNAP, 14-3-3 proteins, and calmodulin on priming and triggering of regulated exocytosis.

We have used stage-specific assays for MgATP-dependent priming and for Ca(2+)-activated triggering in the absence of free MgATP to examine the effects of alpha-SNAP, 14-3-3 proteins and calmodulin on regulated exocytosis in permeabilized adrenal chromaffin cells. All three proteins lead to a Ca(2+)-dependent increase in catecholamine secretion. Both alpha-SNAP and 14-3-3 proteins stimulated in a priming but not in a triggering assay. In contrast, calmodulin was stimulatory in triggering but not priming. The effects of alpha-SNAP and 14-3-3 proteins were likely to be due to distinct mechanisms of action since they differed in Ca(2+)-dependency, time course and extent of stimulation and their effects were additive. alpha-SNAP and 14-3-3 proteins did not appear to exert their priming action through changes in synthesis of phosphatidylinositol (4,5) bisphosphate. The data show that these three proteins have distinct stage-specific actions on exocytosis and indicate that alpha-SNAP acts in an early MgATP-requiring stage and not in the late Ca(2+)-triggered steps immediately prior to membrane fusion as previously suggested.

14-3-3 Proteins↗
PubMed1995

Analgesic effect in humans of subanaesthetic isoflurane concentrations evaluated by experimentally induced pain.

The analgesic effect of subanaesthetic concentrations of ether, trichloroethylene, methoxyflurane and halothane has been investigated previously using either clinical assessment or pain threshold measurements, but with conflicting results. The purpose of the present study was to evaluate the analgesic effect of isoflurane using experimental pain models. We studied 12 healthy volunteers at three randomly chosen subanaesthetic isoflurane concentrations: low (0.10-0.14 vol%), middle (0.16-0.20 vol%) and high (0.22-0.26 vol%). We used thermal pain detection and pain tolerance thresholds to argon laser stimulation, pressure pain detection and pain tolerance thresholds, immersion of the hand in ice water, and the nociceptive reflex to single and repeated (temporal summation) electrical stimulations, as experimental models to assess analgesia. There were no significant changes in the response to heat, cold or mechanical pressure at any of the subanaesthetic concentrations of isoflurane used. The nociceptive reflex thresholds to single stimulations, but not the thresholds for repeated stimulations, were significantly increased in all three isoflurane groups compared with baseline values. The difference between the different isoflurane concentrations was not statistically significant. In experimental pain models, subanaesthetic isoflurane concentrations have little or no analgesic potency.

Adult↗
PubMed1995

Effect of demographic and behavioral variables on burden of caregivers of chronic mentally ill persons.

OBJECTIVE: Persons who provide care for individuals with chronic mental illness experience both objective burden (observable, tangible cost) and subjective (perceived) burden. This study sought to determine the relative power of behaviors of chronic mentally ill clients, behaviors required of caregivers, and demographic characteristics of both groups in predicting burden. METHODS: A total of 189 caregiver-client dyads were studied using a cross-sectional, correlational design. Caregivers were interviewed by phone about clients' needs for help in nine areas and about seven potentially troublesome client behaviors. Correlation and regression analyses were used to determine relationships among variables. RESULTS: Caregivers reported much less subjective than objective burden, although the relationship between the two types of burden was not consistent across the various areas in which clients needed help. Overall, more of the reported burden was related to caregivers' behaviors (their day-to-day tasks) than to clients' behaviors. Burden was greatly increased for caregivers who lived with the client. Caregivers most at risk for burden were those who lived with male clients who threatened suicide. CONCLUSIONS: Caregivers become accustomed to the stabilized behavioral profile of the client. Mental health professionals should be sensitive to profiles and situations that may produce increased objective and subjective caregiver burden.

Adult↗
PubMed1995

Dietary protein restriction, blood pressure control, and the progression of polycystic kidney disease. Modification of Diet in Renal Disease Study Group.

In the Modification of Diet in Renal Disease Study, a follow-up (mean, 2.2 yr) of 200 study participants with autosomal dominant polycystic kidney disease (ADPKD) was conducted to determine the effect of lowering protein intake and blood pressure on the rate of decline in GFR. The rate of decline was faster in participants with ADPKD than in persons with other diagnoses, reflecting, in part, faster disease progression in the ADPKD group. Baseline characteristics that predicted a faster rate of decline in GFR in persons with ADPKD were greater serum creatinine (independent of GFR), greater urinary protein excretion, higher mean arterial pressure (MAP), and younger age. In patients with initial GFR values between 25 and 55 mL/min per 1.73 m2, neither assignment to a low-protein diet group nor assignment to a low blood pressure group significantly reduced the rate of decline of GFR in ADPKD participants. Similarly, the decline in GFR was not related to achieved protein intake or MAP. In participants with GFR values between 13 and 24 mL/min per 1.73 m2, assignment to the low MAP group led to a somewhat more rapid decline in GFR. However, the more rapid decline in GFR did not appear to be due to a detrimental effect of low blood pressure or the antihypertensive agents used to reach the low blood pressure goal. Lower protein intake, but not prescription of the keto acid-amino acid supplement, was marginally associated with a slower progression of renal disease.

Adult↗
PubMed1995

Early development of acute myelogenous leukemia following kidney transplantation: possible role of multiple serum cytokines.

We report a patient who at the time of kidney transplantation for polycystic kidney disease was found to have an enlarged inguinal lymph node which later demonstrated evidence of extra medullary granulopoiesis. During the first two weeks following kidney transplantation, a striking leukemoid pattern developed and 2 months after transplant the patient was diagnosed with acute myelogenous leukemia (AML). Retrospective analysis of peripheral blood cytokines over this time revealed elevated levels of GMCSF and gamma IFN at the time of peak peripheral blood WBC with subsequent peaks in IL-4, IL-6 and IL-2 as the peripheral blood WBC fell. A rise in levels of TNF alpha also preceded the peripheral blood WBC rise (although these concentrations were at or below those following uncomplicated kidney transplants). The clinical course of AML in this patient was marked by relentless relapse despite chemotherapy. The possibility of cytokine facilitated tumor growth is discussed.

Adult↗
PubMed1994

SNAP-25 is present in a SNARE complex in adrenal chromaffin cells.

SNAP-25 (synaptosomal-associated protein 25 kDa) is a target for botulinum neurotoxins A and E, which both inhibit neurotransmitter release, and was recently identified together with syntaxin and synaptobrevin as receptors for NSF and alpha-SNAP. We show that SNAP-25 was enriched in the microsomal fraction from adrenal medulla, although the level of SNAP-25 in adrenal medullary microsomes was about 20-fold less than in brain microsomes. Immunocytochemistry confirmed the presence of SNAP-25 in cultured chromaffin cells and showed plasma membrane staining. Using immunoprecipitation, we found that SNAP-25 was present in a complex with syntaxin, synaptobrevin, synaptotagmin, NSF, alpha-SNAP and other unidentified polypeptides. These data indicate that SNAP-25 in chromaffin cells is present in a complex similar to that identified in brain.

Adrenal Medulla↗
PubMed1994

Characterization of a monoclonal antibody recognizing an epitope designated as canine leukocyte-associated antigen.

An IgG1 monoclonal antibody (mAb), designated as 15F1.5, was generated against surface determinants of a dog peripheral blood-derived PHA-induced IL-2-dependent T cell line. It reacted with 65-80% of peripheral blood mononuclear cells (PBMCs), 90-95% of polymorphonuclear cells (PMNs), 65-70% of thymocytes, 85-95% of Thy-1 positive cells and 85-95% of IL-2-dependent T lymphoid cells in flow cytometry. It was nonreactive with peripheral blood red cells and platelets. It immunoprecipitated 95 and 150 Kd proteins derived from detergent solubilized lymphocyte membranes. Indirect immunofluorescent and immunoperoxidase staining of frozen tissue sections demonstrated positive reactivity to cells in lymphoid but not nonlymphoid tissues. The 15F1.5 antibody was not directly mitogenic for PBMC's. It caused significant decrease (P < or = 0.05) in the lymphoproliferative response to T-dependent B cell mitogens, such as pokeweed mitogen (PWM) and staphage lysate (SPL), without significant effects on responses to the T cell mitogens, phytohemagglutinin (PHA), and concanavalin A (Con A). The mixed lymphocyte culture (MLC) response and both the proliferative and effector arms of the cell-mediated cytotoxicity reactions (CMC) were inhibited in a dose-dependent manner. The mAb also inhibited the auto- and allolymphoproliferative reactivity of mixed lymphocyte kidney or islet cell cultures (MLKC and MLIC), and the adhesion of T lymphoblasts and PMA-treated PMNs to endothelial cells. In vivo administration of the 15F1.5 (20 mg/day for 5 days) caused an immediate and prolonged reduction in MLC responses, associated with cell binding of the mAb to PBMC and epitope modulation during the course of treatment, as indicated by flow cytometry. These results suggest that 15F1.5 is an immunomodulating antibody reacting with canine LFA-1. Thus, this mAb would be useful in studying the role of LFA-1/ICAM-1 in graft rejection as well as other inflammatory responses. It would also allow the use of an animal model to investigate the immunoregulatory effects of in vivo administration of anti-CD11/CD18 antibodies in organ/tissue transplants.

Animals↗
PubMed1994

Characterization of 14-3-3 proteins in adrenal chromaffin cells and demonstration of isoform-specific phospholipid binding.

Isoform-specific antisera were used to examine which 14-3-3 isoforms were present in bovine adrenal chromaffin cells. The eta, tau and sigma isoforms were not detectable, and the epsilon isoform was present at only low levels. 14-3-3 isoforms were readily detected with antisera against the beta, gamma and zeta isoforms. The latter isoforms were found to leak from digitonin-permeabilized chromaffin cells, as expected for cytosolic proteins, but a proportion of each isoform was retained. In subcellular fractionation studies isoforms recognized by the beta and zeta antisera were found in the cytosol and Triton-insoluble cytoskeletal fractions, while the gamma isoform was found in cytosol and also in microsomal and chromaffin granule membrane fractions. The gamma 14-3-3 protein associated with granule membranes was partially removed by a high-salt/carbonate wash, and the membranes could bind further gamma from cytosol or from a purified brain 14-3-3 protein mixture. The binding of gamma 14-3-3 was not Ca(2+)-dependent, nor was it affected by phorbol ester, GTP analogues or cyclic AMP. Using pure phospholipid vesicles it was found that gamma and also epsilon 14-3-3 proteins bound directly to phospholipids. Little binding of brain beta, eta or zeta to phospholipid vesicles was detected. Brain 14-3-3 proteins were also able to aggregate phospholipid vesicles. Recombinant 14-3-3 isoforms (tau and the Xenopus protein) were able to stimulate Ca(2+)-dependent exocytosis in digitonin-permeabilized chromaffin cells. The Xenopus proteins lacks part of the extreme N-terminus, indicating that this domain is not essential for function in exocytosis.

14-3-3 Proteins↗
PubMed1994

Depletion of hepatitis C virus from procured kidneys using pulsatile perfusion preservation.

The safety of the use of kidneys procured from a hepatitis C virus (HCV)-positive cadaver donors in transplantation has recently been the subject of controversy. One factor that is important in determining the transmission of the virus and/or viral liver disease is the total viral inoculum to which the renal allograft recipient is exposed as a result of the transplant. We have studied the effect of a standard pulsatile renal preservation procedure and variations of it on the number of viral copies in organs from HCV-positive donors. An HCV-RNA quantitative reverse transcription-polymerase chain reaction (RT-PCR) method was utilized with a recombinant competitive inhibitor substrate added after cDNA synthesis with the PCR primers within the relatively non-polymorphic 5' untranslated region of the HCV genome. Additionally, strain specificity was found to be detectable using a modification of the technique of restriction fragment-length polymorphism (RFLP-PCR), so that virus from the organ donor could be specifically identified and quantified in the recipient. It was observed that standard preservation procedures using pulsatile perfusion were able to eliminate 75% of the virus from the organ in 20 hr. By modifying this procedure to include additional wash steps and a second pulsatile perfusion, greater than 99% of the virus could be eliminated from the kidney. In a related study, we used quantitative PCR to study requirements for filtration of the virus using HCV-positive serum. It was found that a high-flow-rate ultrafilter with a molecular weight cut-off (MWCO) of 300,000 daltons placed in series to the preservation apparatus was very efficient in eliminating the virus from perfusion solution in less than 2 hr. It can therefore be proposed that with the use of these molecular techniques, pulsatile perfusion coupled with additional viral depletion steps (dilution, and/or filtration) may allow the practical reduction of HCV transmission risk in recipient follow-up studies. The means are thereby presented for similar manipulation of other known or, as yet, unknown transmissible agents.

Base Sequence↗