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Biomedical subjects

M Barnett

Publications and source records attributed to M Barnett.

At least 19 recordsLinked to original sources
PubMed1992

A prospective study of transmission by transfusion of HTLV-I and risk factors associated with seroconversion.

To evaluate the risk of transfusion-related transmission of HTLV-I in Jamaica, a prospective study was initiated, prior to availability of a licensed HTLV-I serological screening assay. This information would prove useful in formulating strategies for blood-donor screening. We followed 118 pre-transfusion HTLV-I-negative transfusion recipients at monthly intervals post-transfusion for 1 year. Laboratory and questionnaire data were obtained at each visit to evaluate the clinical and immunological status of recipients. Cumulative incidence of HTLV-I seroconversion was estimated and risk-factor data associated with seroconversion among 66 HTLV-I-exposed transfusion recipients were analyzed. Seroconversion occurred in 24/54 (44%) of recipients of HTLV-I-positive cellular blood components, 0/12 recipients of positive non-cellular donor units and 0/52 recipients of HTLV-I-negative donor units. Significant risk factors associated with recipient seroconversion were receipt of a seropositive cellular blood component stored for less than one week [odds ratio (OR) = 6.34, 95% confidence interval (CI) = 1.83 to 21.92], male sex (OR = 4.79, 95% CI = 1.15 to 20.0) or use of immuno-suppressive therapy at time of transfusion (OR = 12.20, 95% CI = 0.95 to 156). Risk of blood-borne infection per person per year in Jamaica was estimated to be 0.009%. Our results confirm that blood transfusion carries a significant risk of HTLV-I transmission and that screening of donor blood effectively prevents HTLV-I seroconversion. Recipients at greatest risk for seroconversion were those who required multiple transfusions or who were receiving immunosuppressive therapy at the time of transfusion. These patients should be given priority in receiving selectively screened blood components, if universal blood-donor screening for HTLV-I is not possible.

Blood Donors↗
PubMed1992

The longitudinal effect of inhibiting fatty acid oxidation in diabetic rats fed a high fat diet.

This study was designed to examine the time-course of response to inhibition of fatty acid (FA) oxidation in rats rendered mildly diabetic with streptozotocin and fed a high fat diet (50% of energy derived from fat). Etomoxir, a specific carnitine palmitoyltransferase (CPT-1) inhibitor, was administered subcutaneously (12.5 mg/kg) to inhibit long chain fatty acid oxidation. Diabetic and non-diabetic control rats were maintained on the high fat diet. Following an overnight fast, glucose, free fatty acid (FFA) and triglyceride (TG) concentrations were determined after three days, one week and four weeks of treatment. The effect of Etomoxir treatment in reducing fasting glucose concentrations was not evident until after one week, while fasting FFA and TG concentrations were already reduced after three days treatment. All of these changes were maintained over the four week period (P less than 0.001), resulting in reduced levels of fasting plasma glucose (17.6 +/- 2.4 vs 22.3 +/- 1.9 mmol/l), fasting plasma TG (0.32 +/- 0.07 vs 0.98 +/- 0.14 mmol/l) and fasting serum FFA (1.52 +/- 0.26 vs 3.51 +/- 0.69 mEq/l). In addition, the improvements in glucose and lipid levels were accompanied by restored rates of growth towards that of non-diabetic control rats. These results suggest that the short term inhibition of FA oxidation improves fasting glucose, FFA and TG concentrations in diabetic rats fed a high fat diet.

Animals↗
PubMed1991

Outcome of treatment of first relapse of Hodgkin's disease after primary chemotherapy: identification of risk factors from the British Columbia experience 1970 to 1988.

The outcome of treatment for a first relapse of Hodgkin's disease after primary chemotherapy was analyzed in 80 patients. They were divided into four groups: group 1 (n = 24) had initially been treated with three cycles of (mechlorethamine, vincristine, prednisone, and procarbazine [MOPP]) and wide-field irradiation therapy; group 2 (n = 25) had six cycles of MOPP; group 3 (n = 15) and group 4 (n = 16) both initially received MOPP/ABVD (MOPP plus doxorubicin, bleomycin, vinblastine, and dacarbazine) or MOPP/ABV hybrid, but group 3 received conventional salvage regimens whereas group 4 was treated with high-dose chemotherapy and autologous bone marrow transplantation as salvage therapy (n = 16). Freedom from second failure (FF2F) was used as the major endpoint. Actuarial FF2F for all patients was 38% after a median follow-up of 75 months for patients who were alive. Risk factor analysis was performed on the 71 patients who had been treated with curative intent. The presence or absence of any one of three risk factors had a strong negative impact on outcome: stage IV disease at primary diagnosis, B symptoms at relapse, or a time from primary treatment to relapse of less than 1 year. Actuarial FF2F at 5 years was 17% in the group of patients with one or more of these three factors present (n = 49). If none of these factors was present, FF2F was 82% (n = 22) (P less than .001). Even high-dose chemotherapy and autologous bone marrow transplantation were not able to overcome the negative impact of one or more risk factors (FF2F = 19%, n = 12). The outcome of salvage treatments depends most on the presence or absence of these three risk factors and less on the type of salvage treatment. Patients with none of these risk factors present have an excellent outcome if they are treated with non-cross-resistant chemotherapy, or radiotherapy, or both. Novel approaches are needed for patients with one or more of these factors present. Reports on salvage treatments for Hodgkin's disease in first relapse after primary chemotherapy should include data on the proportion of patients having stage IV disease at diagnosis, B symptoms at relapse, and a time from primary treatment to relapse of less than 1 year.

Adolescent↗
PubMed1991

Detection of early human T-cell lymphotropic virus type I antibody patterns during seroconversion among transfusion recipients.

From a cohort of human T-cell lymphotropic virus type I (HTLV-I) exposed transfusion recipients (N = 71) enrolled in the Jamaican Transfusion Study, 11 were selected for detailed laboratory evaluation. All recipients were followed at monthly intervals for 6 months and then bimonthly up to 1 year for evidence of HTLV-I seroconversion. Without regard to results on screening assays, pretransfusion and posttransfusion samples were tested with two licensed HTLV-1 whole-virus screening enzyme immunoassays (EIAs), recombinant EIAs for antibody against tax (p40x) and p21e envelope, standard whole virus Western blot (WB), WB enhanced with recombinant p21e, and radioimmunoprecipitation assay (RIPA). In the early period posttransfusion, antibody to gag core protein was predominant with anti-p24 generally appearing before anti-p19. Recombinant anti-p21e envelope protein, in EIA and WB format, was frequently the earliest envelope reactivity detected, while anti-gp46 in WB and anti-gp61/68 in RIPA system appeared later. Anti-tax antibodies appeared later in the time course of seroconversion. The whole-virus EIAs were less sensitive than the confirmatory assays. The combination of WB and RIPA or WB enhanced with recombinant p21e appeared equally effective in confirming samples as positive by the Public Health Service two gene group confirmatory algorithm. However, specificity of this assay approach could not be addressed in this study.

Adolescent↗
PubMed1989

Plasma exchange for Guillain-Barré syndrome.

The impact of plasma exchange (PE) on the treatment of severe Guillain-Barré syndrome (GBS) was studied by comparing all the 16 patients treated with PE in a London teaching hospital between January 1985 and August 1987, with 64 historical controls drawn from a series of patients observed during a prospective study in South East England in 1983 and 1984. There were no GBS-related deaths in the PE treated group but seven in the historical controls (2P = 0.39). The median duration of ventilation was only 20 days (range 7-64) in the PE group compared with 36 days (range 14-365) in the surviving patients in the control group (2P = 0.06, 95% confidence interval of difference in medians -36 to 0 days). The PE group walked earlier without aid (median 55.5 compared with 86 days, 2P = 0.04, 95% confidence interval of difference in medians -88 to -2 days). Three months after the onset of neuropathy all PE treated patients were able to walk with support or better, whereas 19 of the surviving historical controls were unable to walk even with support (2P = 0.009). The costs of PE were offset by savings in intensive care unit and hospital expenditure.

Adult↗
PubMed1987

Management of Guillain-Barré syndrome.

Guillain-Barré syndrome is a predominantly motor polyradiculoneuropathy in which neurological deficit reaches a peak within 1 month of onset. Seventy per cent of patients recover within 1 year, but 10% die and 20% have residual disability. Plasma exchange is advocated for severe cases early in the course of the disease but the role of steroids has yet to be determined.

Female↗
PubMed1986

Spectrum of HTLV-III infection in a hemophilic cohort treated with blood products from a single manufacturer.

One hundred fifty-eight hemophilia A, B, and von Willebrand disease (VWD) patients treated with clotting factor concentrates from a single manufacturer were tested for antibody to the human T-lymphotropic virus type III (HTLV-III). Antibody was detected in 63% and 40% of those with severe hemophilia A and B, respectively, 12% and 0% of those with mild hemophilia A and B, and two patients with recessive VWD. Forty-two antibody-positive and 20 antibody-negative patients were studied for clinical and laboratory features of infection. Eleven seropositive patients had clinical signs of infection including Pneumocystis carinii pneumonia, lymphadenopathy, splenomegaly or diarrhea; however, only one patient had developed acquired immune deficiency syndrome (AIDS), and only two had significant impairment of their performance status. Thirty-one patients remained totally asymptomatic. Eight patients had a history suggestive of acute HTLV-III infection. Thrombocytopenia was observed in 18% of seropositive patients, lymphopenia in 60%, depressed T-helper cells in 43%, reduced T-helper:T-suppressor ratios (TH:TS) in 33%, and elevated platelet-bound immunoglobulin in 53%. The antibody-negative group had normal T-helper cell levels (except one patient) and TH:TS ratios, and normal platelet immunoglobulin levels. Both groups demonstrated a significant elevation of immunoglobulin levels and a high prevalence of antinuclear factor and antismooth muscle antibodies. The mean level of IgG was significantly higher in the antibody-positive group. This study confirms the correlation between HTLV-III infection and reduced T-helper cells in hemophiliacs but demonstrates a low incidence of clinical symptomatology. There was evidence of polyclonal B-cell hyperactivity in the antibody-negative group as well as the seropositive group.

Acquired Immunodeficiency Syndrome↗
PubMed1986

bcr rearrangement and translocation of the c-abl oncogene in Philadelphia positive acute lymphoblastic leukemia.

The Philadelphia (Ph1) chromosome, the cytogenetic hallmark of chronic myeloid leukemia (CML), has also been detected in a significant number of acute lymphoblastic leukemias (ALL). Using in situ hybridization, we demonstrate that in accordance with observations in CML the Ph1 chromosome in ALL patients is the result of a consistent translocation of the c-abl oncogene to the Ph1 chromosome. Southern blot analysis using bcr probes, however, suggests that Ph1-positive ALL includes heterogeneous leukemic subtypes: six ALL patients showed bcr rearrangements as observed in CML; in three other patients recombination involving 5' bcr sequences could be demonstrated, but the corresponding translocated 3' bcr sequences were not detectable. A third group of five patients did not show any bcr rearrangements at all. Northern blot analysis using RNA from three Ph1-positive ALL patients revealed that in the leukemic cells of two patients larger c-abl mRNA transcripts were present, as in CML. In the RNA of one patient without a detectable bcr rearrangement, only the normal c-abl mRNA transcripts are present. The observed heterogeneity in bcr rearrangements of this group of Ph1-positive ALL patients is in contrast with the consistent results obtained in more than 50 Ph1-positive CML patients investigated in chronic and acute states.

Chromosome Deletion↗
PubMed1985

Long-term clean intermittent self-catheterization in renal transplant recipients.

Eight renal transplant recipients with neurogenic bladders or lower urinary tract dysfunction were managed with clean intermittent self-catheterization after transplantation instead of urinary diversion. A total of 85 treatment months was reviewed. Of the patients 5 continue to do well after 10 to 17 months of intermittent catheterization and 3 suffered immunological graft failures. In selected renal transplant recipients with lower urinary tract dysfunction clean intermittent catheterization is a reasonable alternative to urinary diversion.

Adolescent↗
PubMed1985

Misstaging of ovarian cancer.

The thoroughness of intraoperative evaluation of the extent of disease in 291 women with primary ovarian cancer was investigated. Notable differences among physician specialties but not types of hospitals where initial surgery was performed were observed. A review of medical record documentation revealed that 97% of the cases operated on by gynecologic oncologists had complete staging evaluations performed intraoperatively, but only 52 and 35% of cases operated on by obstetricians/gynecologists and general surgeons, respectfully, were adequately evaluated. Roughly one-half of the cases diagnosed in community hospitals and in hospitals with teaching affiliations were found to be completely studied, and 66% of those operated on in university hospitals received complete intraoperative evaluations.

Diagnostic Errors↗
PubMed1979

Iron overload despite partial gastrectomy.

Iron overload was found in 3 patients who had undergone partial gastrectomy: a 61-year-old woman developed iron overload because she may have had idiopathic haemochromatosis and had also been given parenteral iron; in a 62-year-old man with thalassaemia minor, iron overload may have developed because of increased oral iron ingestion, low serum folate, increased, albeit ineffective, erythropoiesis and sideroblastic anaemia; a 74-year-old man with thalassaemia minor developed iron overload without exogenous therapy and died from a hepatoma. These cases illustrate that partial gastrectomy fails to protect patients from developing iron overload, particularly if given uncontrolled iron therapy.

Aged↗