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Biomedical subjects

M Carver

Publications and source records attributed to M Carver.

At least 19 recordsLinked to original sources
PubMed2001

Effects of calorie and fluid intake on adverse events during hemodialysis.

PURPOSE: To investigate the incidence of adverse events during hemodialysis treatments as a function of calories and fluid intake. METHODS: The study period was August 3-26, 1999. Hemodialysis visits were studied. Twenty-three patients receiving hemodialysis during the 2nd shift on Tuesday, Thursday, and Saturday were studied. A total of 166 hemodialysis patient visits were studied. Data collected included: amount of fluid and food consumed, blood pressure levels, and mannitol use during each hemodialysis treatment; and any symptoms that occurred either during or after the dialysis treatment (hypotension, nausea, vomiting, diarrhea, cramping, and access problems). RESULTS: Using regression analysis, calories and fluids were strong predictors of both hypotension (P =.003) and mannitol use (P =.000), but not of cramping or access problems. Patients were 3 times more likely to have hypotension if taking any fluids (P =.011). Patients consuming >200 calories were 2 times as likely to have hypotension (P =.058). Patients were 5 times more likely to use mannitol if taking any fluids (P =.005). Mannitol use increased significantly (P =.001) with those patients consuming >200 calories. CONCLUSION: Patients who ate more than 200 calories and consumed more than 200 mL of fluid during hemodialysis had an increased incident of hypotensive events and increased use of mannitol.

Aged↗
PubMed2000

Next day telephone follow up of the elderly: a needs assessment and critical incident monitoring tool for the accident and emergency department.

BACKGROUND: Patients over the age of 75 years comprise an increasing proportion of accident and emergency (A&E) department attendances. Within this group there is a high incidence of comorbidity, which mandates effective discharge coordination from the A&E department. OBJECTIVES: The aims of this study were to assess the needs of these patients the day after discharge, target patients for appropriate interventions and identify critical incidents. SETTING: The study was undertaken in a district general hospital A&E department that has 62000 new patient attendances per year. INCLUSION CRITERIA: Patients aged 75 years or over who were discharged from the A&E department. EXCLUSION CRITERIA: Nursing home patients. Patients without a telephone. STUDY DESIGN: Pre-discharge information was collected from the medical notes. A community liaison nurse (CLN) then contacted patients by telephone. A semistructured questionnaire was used to assess patients. Patients were risk stratified and appropriate interventions made. Interventions initiated by the CLN were scored from 1 to 6 based on the level of input required. RESULTS: 551 patients or their carers were contacted by telephone. Existing home support was felt to be insufficient in 44 (8%) cases and in need of immediate intervention in a further 45 (8%) cases. Sixty five (11%) Category 1 patients required no intervention, 223 (42%) Category 2 patients required advice only, 107 (19%) Category 3 patients were referred to their GP, 127 (23%) Category 4 patients required a domicillary visit by a GP or a nurse, 26 (5%) Category 5 patients were at risk requiring urgent home assessment and three Category 6 patients had to re-attend A&E. Advice was given by the CLN on a broad range of issues and a wide range of health care services was accessed. Five hundred and fifty nine referrals were made by the CLN after telephone assessment. CONCLUSIONS: Telephone follow up of patients over 75 attending our A&E department identified a number of areas where care could be improved before and after discharge. This low cost, high quality intervention has the potential for decreasing inappropriate return visits to the department by a vulnerable group of patients as well as improving overall quality of care.

Aged↗
PubMed1992

The development of a posttransplant TLI treatment strategy that promotes organ allograft acceptance without chronic immunosuppression.

The effectiveness of fractionated TLI in promoting allograft tolerance without chronic drug therapy is well established experimentally. TLI has not been widely applied in clinical transplantation, largely due to logistic and medical limitations of pretransplant TLI conditioning. Potential use of posttransplant TLI (PT-TLI) has not been critically evaluated. In this study we investigated PT-TLI in combination with rabbit antithymocyte globulin (RATG) in the absence of chronic immunosuppressive drugs as a strategy for inducing long-term kidney allograft acceptance. Recipients were studied with and without infusion of DR-CD3- donor bone marrow cells (DBMC). Normal rhesus monkeys, which received no pretransplant treatment, underwent bilateral intrinsic nephrectomy and splenectomy at the time of transplantation. RATG was administered daily for 3-5 consecutive days beginning on day 0. A total dose of 500-625 cGy of fractionated TLI was given in 4-5 treatments at 125 cGy per day beginning on day +1. Whereas neither PT-TLI nor RATG monotherapy induced long-term graft acceptance in splenectomized recipients, the combination of these modalities was remarkable in promoting long-term allograft acceptance without immunosuppressive drug therapy. Of 4 recipients given RATG x 5, splenectomy and PT-TLI, all were free of acute rejection. Of these, 3/4 had graft survivals greater than 100 days, 2/4 were greater than 150 days and 1/4 greater than 365 days. Of 5 recipients given this treatment plus an infusion of DR-CD3-DBMC, 4/5 grafts survived greater than 150 days and 3/5 still have normal functioning grafts at greater than 365 days. PT-TLI accentuated and prolonged changes in PBL subpopulations that were initially affected by RATG. Depressed levels of CD3+ cells were present for 4-5 months, with large numbers of circulating CD4+CD3- and especially CD8+ CD3- cells. In addition, antibody responses to RATG and alloantigens were suppressed in PT-TLI-treated recipients. Overall, the combination of PT-TLI, splenectomy, and RATG was found to be effective in promoting long-term allograft acceptance without chronic immunosuppressive drug therapy. The infusion of DR-CD3- DBMC in recipients treated with PT-TLI, RATG and splenectomy appeared to further increase the incidence of stable long-term survivors. If infectious complications can be improved, this approach may provide a clinically applicable posttransplant treatment strategy for inducing functional allograft tolerance.

Animals↗
PubMed1990

Membrane ionic currents in Rhodobacter capsulatus. Evidence for electrophoretic transport of K+, Rb+ and NH4+.

1. The cytoplasmic membrane ionic current of cells of Rhodobacter capsulatus, washed to lower the endogenous K+ concentration, had a non-linear dependence on the membrane potential measured during photosynthetic illumination. Treatment of the cells with venturicidin, an inhibitor of the H(+)-ATP synthase, increased the membrane potential and decreased the membrane ionic current at values of membrane potential below a threshold. 2. The addition of K+ or Rb+, but not of Na+, led to an increase in the membrane ionic current and a decrease in the membrane potential in either the presence or absence of venturicidin. Approximately 0.4 mM K+ or 2.0 mM Rb+ led to a half-maximal response. At saturating concentrations of K+ and Rb+, the membrane ionic currents were similar. The membrane ionic currents due to K+ and Rb+ were not additive. The K(+)-dependent and Rb(+)-dependent ionic currents had a non-linear relationship with membrane potential: the alkali cations only increased the ionic current when the membrane potential lay above a threshold value. The presence of 1 mM Cs+ did not lead to an increase in the membrane ionic current but it had the effect of inhibiting the membrane ionic current due to either K+ or Rb+. 3. Photosynthetic illumination in the presence of either K+ or Rb+, and weak acids such as acetate, led to a decrease in light-scattering by the cells. This was attributed to the uptake of potassium or rubidium acetate and a corresponding increase in osmotic strength in the cytoplasm. 4. The addition of NH4+ also led to an increase in membrane ionic current and to a decrease in membrane potential (half-maximal at 2.0 mM NH4+). The relationship between the NH4(+)-dependent ionic currents and the membrane potential was similar to that for K+. The NH4(+)-dependent and K(+)-dependent ionic current were not additive. However, illumination in the presence of NH4+ and acetate did not lead to significant light-scattering changes. The NH4(+)-dependent membrane ionic current was inhibited by 1 mM Cs+ but not by 50 microM methylamine. 5. It is proposed that the K(+)-dependent membrane ionic current is catalysed by a low-affinity K(+)-transport system such as that described in Rb. capsulatus [Jasper, P. (1978) J. Bacteriol. 133, 1314-1322]. The possibility is considered that, as well as Rb+, this transport system can also operate with NH4+. However, in our experimental conditions NH4+ uptake is followed by NH3 efflux.(ABSTRACT TRUNCATED AT 400 WORDS)

Ammonia↗
PubMed1989

Altered pharmacokinetics of antibiotics during vascular surgery.

Prophylactic antibiotics significantly decrease the incidence of infection in various surgical procedures. Although antibiotics must be administered preoperatively to be effective, it is unknown whether therapeutic concentrations are necessary throughout the operation to prevent infection. Furthermore, the pharmacokinetics of antibiotics during surgical procedures is not well understood. Several factors, including blood loss, fluid redistribution, and changes in renal blood flow may alter the pharmacokinetic disposition of the antibiotic. In a controlled investigation of intraoperative antibiotic pharmacokinetics, cefamandole was studied in eight patients undergoing elective surgery of the abdominal aorta and peripheral vasculature. Both elimination half-life (67 +/- 19 minutes versus 93 +/- 23 minutes) and the volume of distribution (16.8 +/- 5.3 liters versus 25.2 +/- 11.9 liters) increased when compared with the preoperative state. The increased volume may be due, in part, to redistribution of fluid. Plasma concentrations of antibiotic were low at the time of graft placement in those patients with normal renal function. Additional antibiotic dosing may be warranted prior to prosthesis insertion in these patients.

Aorta, Abdominal↗
PubMed1989

Promotion of incompatible allograft acceptance in rhesus monkeys given posttransplant antithymocyte globulin and donor bone marrow. II. Effects of adjuvant immunosuppressive drugs.

Previous studies from this laboratory demonstrated prolonged acceptance of MHC-mismatched kidney allografts in rhesus monkeys treated with posttransplant rabbit antithymocyte globulin (RATG)* and donor-specific bone marrow (DBM). Here we have investigated the effect of adjunctive immunosuppressive drugs on induction of allogeneic unresponsiveness in this primate model. Parameters examined included median kidney allograft survival time (MST), development of specific antidonor T lymphocyte-mediated cytotoxicity (LMC) and antidonor antibody-dependent cellular cytotoxicity (ADCC). Posttransplant infusion of DBM in RATG-treated kidney allograft recipients resulted in 70 days MST and a dramatic reduction in the incidence of antidonor LMC. However, development of antidonor ADCC was similar to that of RATG controls, suggesting an immune deviation or split tolerance in these animals. Adjunctive azathioprine did not have a beneficial effect in recipients given RATG & DBM, resulting in decreased MST and increased antidonor LMC responses. In contrast, adjunctive cyclosporine (CsA) and low-dose prednisone (P) exerted an additive immunosuppressive effect resulting in a 50% increase in MST and no detectable antidonor LMC. However, CsA & P appeared to enhance the humoral alloimmune response, increasing the incidence of recipients with antidonor ADCC. Long-term graft survival in this group was limited by chronic rejection and especially by CsA-associated toxicity. These studies point out deterrents and also directions for optimizing adjunctive immunosuppression in primates treated with posttransplant RATG & DBM. The results with CsA are relatively encouraging. However, the prevalence of alloantibody and of chronic rejection in these animals suggests that more homogeneous success with tolerance induction in this model may require adjunctive immunosuppressive strategies that reduce humoral immunity.

Adjuvants, Immunologic↗
PubMed1987

Promotion of incompatible allograft acceptance in rhesus monkeys given posttransplant antithymocyte globulin and donor bone marrow. I. In vivo parameters and immunohistologic evidence suggesting microchimerism.

This report extends previous studies demonstrating that prolonged acceptance of incompatible kidney allografts in rhesus monkeys can be achieved by a short recipient rabbit antithymocyte globulin (RATG) treatment course followed by donor bone marrow infusion on day 12 without a requirement for chronic immunosuppression. Serial studies of antilymphocyte cyctotoxic antibody in recipients' sera following RATG injections showed pan-lymphocyte-reactive antibody present until day 10 posttransplant. On days 11 and 12, pan-lymphocyte-reactive antibody was no longer detectable, but cytotoxic antibody specific for mature T cells remained in recipients' sera. These findings might explain the critical time relationship between antithymocyte globulin treatment and donor bone marrow infusion, and further suggest that the tolerance-promoting cell in donor bone marrow is not a mature T cell, but rather a pre-T or a non-T cell. Finally, it was found that this treatment protocol resulted in development of lymphoid nodules in the transplanted kidney that express a CD8-positive, FcIgG-receptor-positive phenotype and appear to be of donor origin. The possibility of a veto cell type of mechanism is discussed as an explanation for the promotion of allograft acceptance in this model.

Animals↗