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Biomedical subjects

L A Chambers

Publications and source records attributed to L A Chambers.

18 recordsLinked to original sources
PubMed1991

Decrease in reported posttransfusion hepatitis. Contributions of donor screening for alanine aminotransferase and antibodies to hepatitis B core antigen and changes in the general population.

Blood donor screening for hepatitis B core antibody and elevation of serum alanine aminotransferase level, surrogate markers of hepatitis C/non-A, non-B (NANB) infection, was implemented in 1986. Reported cases of posttransfusion hepatitis (PTH) from 1985 to 1988 were reviewed to ascertain the effect of surrogate testing on the number and character of cases and to compare any changes with those in the incidence of hepatitis in the general population. The reports of all PTH, NANB PTH, and type B PTH decreased 61.5%, 75.4%, and 84.5%, respectively. The rates of reported cases of NANB hepatitis and hepatitis B in the general community also fell during the period of review. The decrease in PTH and background hepatitis was similar between 1985 and 1986. In 1987, the first complete year of surrogate testing, the incidence of PTH decreased at a greater rate, to levels 50% below what would have been projected on the basis of background changes alone for NANB PTH, and to 35% below projected for type B PTH. There appears to have been a substantial decrease in the risk of both type B PTH and NANB PTH in the northeastern United States between 1985 and 1988 due to a combined effect of donor surrogate testing and a decrease in the background rates of hepatitis in the donor population.

Alanine Transaminase↗
PubMed1991

Ceftazidime-induced hemolysis in a patient with drug-dependent antibodies reactive by immune complex and drug adsorption mechanisms.

A 35-year-old woman developed acute intravascular hemolysis within five days of beginning a course of ceftazidime. The direct antiglobulin test became strongly positive with both anti-IgG and anticomplement. The serum contained an antibody that, in the presence of ceftazidime, sensitized unmodified reagent cells with IgG and complement (immune-complex type). The serum also agglutinated ceftazidime-pretreated cells at room temperature and 37 degrees C (drug-adsorption type). Retrospective testing disclosed that the drug adsorption antibody, which had been present before the current course of antibiotics, was not demonstrable during the hemolysis. The reactivity of the immune complex antibody, which developed by the second day of ceftazidime, paralleled the degree of hemolysis and the strength of the direct antiglobulin test. The authors believe that this patient had two separate ceftazidime-dependent antibodies and that the antibody reactive by immune complex mechanism mediated an episode of acute intravascular hemolysis.

Adsorption↗
PubMed1991

Limited efficacy of leukopoor platelets for prevention of febrile transfusion reactions.

Leukopoor red cell components have a reduced incidence of febrile transfusion reactions. An analogous efficacy for leukopoor platelets has not been convincingly established. The authors analyzed the transfusion records of 36 patients (26 women, 10 men) who received leukopoor platelets following febrile reactions to unmodified platelets. These patients received 409 unmodified transfusions (mean/patient 11) with 84 febrile reactions (rate 20.5%). Reaction rates to unmodified, non-HLA-matched single donor platelets (14.0%) and HLA-matched platelets (6.5%) were significantly lower than to pooled concentrates (27.2%) (P less than .01 and P less than .001, respectively). Of 623 leukopoor transfusions (mean/patient 17), 84 resulted in reactions (13.5%). Although leukodepletion significantly lowered the overall reaction rate as compared with unmodified products (P less than .02), a majority of patients (28 of 36) continued to have reactions. When individual reaction rates to unmodified and leukopoor transfusions were compared, only two patients showed a significant decrease in their reaction rate with leukopoor platelets. It appears that most susceptible patients continue to react to leukopoor platelets, particularly when pooled concentrates are used, and many patients show no reduction in reaction rate.

Adolescent↗
PubMed1989

Evaluation of methods and protocols for hemoglobin screening of prospective whole blood donors.

Fifty-nine volunteers were screened, as if for blood donation, with the use of simultaneous fingerstick (FS), earlobe (EL), and venipuncture (VP) samples tested by copper sulfate density and two instruments for rapid assay, Statcrit and HemoCue. The "true" hemoglobin was determined on the venipuncture sample by cyanmethemoglobin assay. Eligibility (pass/fail) was established for each site/result with the use of standard and investigational cut-offs. Results were used to predict the performance of two-method protocols beginning with copper sulfate followed by FS or EL using Statcrit or HemoCue. Individually, the method sensitivities for hemoglobin below cut-off were low (12.5-62.5%) with the use of standard cut-offs. Assuming 5% prevalence of low hemoglobin, two-method protocols would inappropriately pass more than half of those with low hemoglobin, whereas the proportion of deferred donors with adequate "true" hemoglobin ranged widely (2.8-72.3%). For some methods, investigational cut-offs achieved improved sensitivity with no effect on specificity. Despite standard hemoglobin "requirements" for blood donation, the ability of the investigated methods to correctly classify donors is poor and varies considerably with method and protocol. With cut-offs as specified, the standards for FS and EL samples are not equivalent; the EL cut-offs are too low and the method is inherently less sensitive. Standardization may be better achieved by specifying both required hemoglobin and minimum performance for screening methods.

Blood Donors↗
PubMed1987

Age and sex differences in new and recurrent cases of guinea worm disease in Nigeria.

In this population-based cross-sectional survey of the prevalence and incidence of guinea worm disease in Idere, a rural agricultural community of Oyo state in Nigeria, epidemiological data were collected by household interview of all 501 households (6527 persons, 3594 females and 2933 males). 86% of the households had at least one case. The prevalence was 32.4% in the overall population, but varied markedly by age and sex. About 10% of prevalent cases were first-time infections or new cases. Males over 19 years of age had a higher prevalence rate than adult females; however, females had a higher prevalence rate at younger ages. The prevalence in females peaked (47%) at 35 to 44 years; for males the proportion was highest (57%) at ages 45 to 54 years.

Adolescent↗
PubMed1986

Impact of guinea worm disease on children in Nigeria.

School attendance records of all primary schools in a guinea worm-endemic village in southwestern Nigeria were examined to determine the cause of missed school days and school drop-outs. At the time of the survey, 1,495 pupils (768 boys and 727 girls were registered in the 4 primary schools in the village, of which 21% of the pupils were infected with guinea worm disease (GWD). Female pupils had a higher infection rate than their male counterparts. Guinea worm-infected pupils missed up to 25% of school year days compared to a non-guinea worm-infected absence of 2.5%. At the height of guinea worm season in the study area, guinea worm-related absences contributed virtually all of the absenteeism recorded in the schools. Implications of the findings within the context of educational attainment of the pupils are discussed.

Absenteeism↗
PubMed1979

Thiosulfate formation and associated isotope effects during sulfite reduction by Clostridium pasteurianum.

During growth of Clostridium pasteurianum on sulfite, approximately half the sulfite was reduced to sulfide and half to thiosulfate. Sulfide was enriched in 32S or 34S at different stages of growth and thiosulfate was enriched in 32S, particularly in the sulfane atom. It is suggested that thiosulfate in these bacterial cultures arose from a secondary chemical reaction. The chemical formation of thiosulfate from sulfide and sulfite was also accompanied by sulfur isotope fractionation. The implications of these results with respect to 'inverse' isotopic effects are discussed.

Clostridium↗
PubMed1976

Metal accumulation by bacteria with particular reference to dissimilatory sulphate-reducing bacteria.

Dissimilatory sulphate-reducing bacteria, genera Desulfovibrio and Desulfotomaculum, exhibit a superior ability, over assimilatory organisms, to extract three amounts of metals from culture media. This property does not appear to be solely a function of the presence of H2S. In media containing elevated amounts of Fe, electron dense particles, provisionally identified as FeS, are deposited within the cells of dissimilatory bacteria.

Bacillaceae↗
PubMed1976

Distribution of trace elements in the Houston environment: relationship to mortality from arteriosclerotic heart disease.

The relationship of trace elements to arteriosclerotic heart disease (AHD) was assessed. Samples of water supplies in the Houston area were analyzed periodically for cadmium, lithium, iron and zinc. Mortality data for each of the sampling areas, delineated according to boundary of water service, were used to compute average annual age-adjusted death rates for white males aged 35 to 64 during the years 1969 to 1971. Linear regression analyses were performed on the chemical constituents for the age-adjusted death rates due to AHD. Positive correlation coefficients for lithium and zinc were found to be statistically significant at the 0.05 probability level.

Adult↗
PubMed1975

Localized intracellular polyphosphate formation by Desulfovibrio gigas.

The dissimilatory sulphate-reducing bacterium Desulfovibrio gigas, frequently sub-cultured, often contained spherical granules which stained metachromatically with some basic dyes. The granules were examined in situ by transmission electron microscopy of whole organisms and thin sections. The granules were isolated from broken bacteria as a water-insoluble, non-crystalline, white material containing magnesium, phosphorus and organic carbon, but devoid of sulphur and nitrogen. The molar ratio of phosphorus to magnesium (1 to 17) was close to the proportions in magnesium tripolyphosphate. Infrared absorption spectra for the white material and magnesium tripolyphosphate were similar.

Carbon↗
PubMed1975

Are thiosulfate and trithionate intermediates in dissimilatory sulfate reduction?

The fate of 35-S during anaerobic metabolism of [35-S]sulfate, [35-S]thiosulfate, and [35-S]sulfate plus unlabeled thiosulfate by washed cell suspensions of Desulfovibrio spp, and of [35-S]thiosulfate by growing D. desulfuricans was examined. The results appear to be inconsistent with the hypothesis that thiosulfate is an intermediate in sulfate reduction. Since thiosulfate was produced from trithionate, the latter is also unlikely to be an intermediate in the reduction pathway. Extracts of D. desulfuricans catalysed exchange between sulfite and the sulfonate group of thiosulfate.

Anaerobiosis↗
PubMedDate not supplied

Febrile reactions after platelet transfusion: the effect of single versus multiple donors.

Febrile reactions to platelet transfusions are a common problem. The platelet transfusion records from a 30-month period were analyzed to determine 1) when reactions occur in a transfusion sequence; 2) how frequently they recur; and 3) whether the choice of multiple-donor (pooled concentrates) or single-donor components (unmatched apheresis and HLA-compatible apheresis platelets) affected the reaction rate. Overall, 18.7 percent of all patients receiving platelets experienced reactions. A subset of 85 patients, who began platelet support with unmodified components during the study interval, were analyzed in detail. This group received 1204 unmodified transfusions (mean, 14.2/patient), which were associated with 171 reactions (per-transfusion reaction rate, 14.2%). Despite a higher mean white cell content, the transfusion of 438 unmatched single-donor platelets (10.84 x 10(8) white cells, 8.4% reaction rate) resulted in reactions significantly less often than did that of 583 pooled concentrates (8.53 x 10(8) white cells, 21.4% reaction rate) (p less than 0.001). The rate of reaction to HLA-compatible platelets (9/183 transfusions, 4.9%) was not significantly different from that to unmatched single-donor platelets. The use of platelet components from one donor, as opposed to multiple donors, may provide an effective means of reducing the incidence of febrile reactions.

Blood Donors↗
PubMedDate not supplied

Directed-donor programs may adversely affect autologous donor participation.

One hundred autologous whole blood donors (11 men, 89 women; 49 preoperative, 51 prenatal) completed a questionnaire concerning their motivations as autologous donors, their perceptions of the relative safety of blood donor options, and their interest in directed donations. Concern about acquiring AIDS from transfusion was the most prevalent reason for autologous donation. Nearly all participants knew that autologous blood was safer than volunteer blood, and most also believed that directed-donor blood was safer than volunteer blood. Most would have used a directed-donor program if available, particularly if they were ineligible as autologous donors. Furthermore, their interest in directed donations was unaffected by written material, provided pathway through the questionnaire, that included a statement that no scientific evidence exists to support directed donations' being safer than volunteer blood. One donor in five believed that autologous and directed donations were equivalent in safety, and 19 (15 of whom were prenatal donors) indicated that they probably or surely would not have participated in the autologous program if directed donations had been available. This study demonstrates that a sizable proportion of autologous donor candidates might not participate if a directed donation program were available. The unrestricted availability of directed donations may thus contribute to suboptimal use of autologous donor programs.

Blood Donors↗
PubMedDate not supplied

The endoscopic diagnosis of gastroesophageal malignancy. A cytologic review.

Cytologic reports were compared to final diagnoses for 1,157 gastroesophageal samples from an eight-year period in order to evaluate the diagnostic accuracy of endoscopic cytology and to determine the significance of a "suspicious" cytologic report. In the subgroup of patients with adenocarcinoma evaluated by paired endoscopic biopsy and cytology, the relative and combined sensitivities of the sampling methods were studied. Cytologic examination was reported as positive or suspicious in 85% of 229 cases of malignancy. There were three false-positive diagnoses of squamous-cell carcinoma of the esophagus, representing 0.3% of all submitted samples. Suspicious cytologic reports were issued in 5% of all cases. The majority (63%) of patients with a suspicious cytologic report had a final diagnosis of malignancy, with gastric adenocarcinoma present in almost half of the cases. Adenocarcinoma was diagnosed in 168 of the patients. Combined endoscopic biopsy and cytology was more sensitive (96%) than biopsy alone (90%) in making the initial diagnosis. Cytology may be of particular value in the diagnosis of gastroesophageal malignancy when the lesions are small and superficial or where stricture precludes adequate biopsy. Regardless of the biopsy findings, patients with "suspicious" cytologic reports require careful reevaluation since a high percentage of those cases in our series were subsequently verified as having malignancy.

Adenocarcinoma↗