Search PubMed⌕ Search

Biomedical subjects

J Bryant

Publications and source records attributed to J Bryant.

At least 19 recordsLinked to original sources
PubMed1992

Calculation of lytic units for the expression of cell-mediated cytotoxicity.

Over the past 10 years, the lytic unit has become the most common means by which activity is expressed in cell-mediated cytotoxicity assays. The strengths and weaknesses of the lytic unit as a summary of cytotoxicity are discussed, and computational methods reviewed. The fundamental "assumption of proportional effect" which is implicit in the interpretation of lytic units is described and empirically tested. Based on extensive data from the assay of human natural killer (NK) activity against K562 targets, simplified computational methods are recommended. The proposed methods are easily explained, may be made robust to occasional erratic data, and permit a reasonable interpretation of lytic units even when the assumption of proportional effect breaks down.

Cytotoxicity Tests, Immunologic↗
PubMed1992

The contamination of pork with spoilage bacteria during commercial dressing, chilling and cutting of pig carcasses.

Swab samples from the surfaces of carcasses and cuts were obtained at various stages of the dressing, chilling and cutting operations in three pig processing plants. The aerobic microflora obtained from those swabs were enumerated and characterized. The flora on the skins of carcasses exiting the scalding tanks were dominated by Gram-positive organisms, with numbers about 10(3)/cm2. After dehairing, numbers were about 10(4)/cm2 with major fractions of Gram-negative organisms. Flora numbers and compositions were largely unaltered after the singeing operations, but lesser numbers were recovered after the carcasses were polished. Carcass dressing did not change the numbers on the skin. During the chilling of carcasses, the flora at two large plants altered little, but drying of the carcass surfaces at a smaller plant reduced the Gram-negative fraction of the flora. Numbers on serous and fat surfaces exposed during the dressing and cutting of carcasses were initially about 10(2)/cm2. That number was approximately maintained on finished skinned cuts produced at the smaller plant, but further contamination with lactobacilli and Brochothrix thermosphacta occurred during cutting. At the larger plants, the flora on skinned cuts were similar to those on skins, although further contamination with B. thermosphacta occurred at one plant.

Abattoirs↗
PubMed1992

The effects of different central venous line dressing changes on bacterial growth in a pediatric oncology population.

Central venous lines are now common in children who need a permanent form of intravenous access. These lines frequently become infected. This study compared the effects of different antiseptics (Hibiclens [chlorhexadine 4%; Stuart Pharmaceutical, Wilmington, DE] and Betadine [povidone-iodine, Clini Pad Corp, Guilford, CT]) used to clean the skin as well as the dressings used to cover the exit site (Tegaderm [3-M Medical-Surgical Division, St Paul, MN] and gauze) on microorganism growth on the skin in a pediatric oncology population. Sixty subjects were recruited from the oncology and bone marrow transplant units of Children's Hospital in Boston, MA. The subjects were randomly assigned to one of four dressing groups. These included: 1, Betadine and Tegaderm; 2, Betadine and gauze; 3, Hibiclens and Tegaderm; and 4, Hibiclens and gauze. Dressings were done on a Monday-Wednesday-Friday basis. Quantitative cultures were obtained before the first and after the fifth dressing changes. There were no significant differences in incidence of bacterial growth between dressing groups (F = 1.05, P = .377). Redness (F = 3.01, P = .037) and swelling (F = 2.75, P = .051) were more frequently seen in Betadine groups. Boys were more often infected than girls. (Chi 2 = 4.075, P = .044).

Adolescent↗
PubMed1992

Surgical wound infection rates: use caution when comparing.

1. Comparing surgical wound infection (SWI) rates without a complete understanding of and at least a partial control for those factors that can account for observed variations can be misleading. 2. Variations in SWI rates can be attributed to patient-related factors, type of operation, differences in case finding, differences in definition of SWI, and chance variation. 3. Use of a risk stratification prior to rate calculation controls for intrinsic (patient-related) and extrinsic (operation-related) risk for the purpose of comparison.

Bias↗
PubMed1992

Perioperative antibiotic prophylaxis: the importance of timing.

1. Although prophylactic antibiotics have demonstrated efficacy in surgical procedures, they can fail because, generally, an inappropriate agent is used or the agent is inappropriately administered. 2. The timing of administration is important. Studies indicate that to reduce the risk of infection, high levels of antibiotic must be present in the bloodstream and tissues at the time of the incision. 3. Nurses play a central role in ensuring the proper timing of the administration of prophylactic antibiotics. Improvement in the timing of administration will reduce both morbidity and institutional costs.

Anti-Bacterial Agents↗
PubMed1991

HIV-associated nephropathy in transgenic mice expressing HIV-1 genes.

Transgenic mice were produced that bore copies of a defective HIV provirus. The transgenic offspring from three independently derived mouse lines manifested renal disease associated with proteinuria, a high mortality rate, and HIV-specific gene expression in the kidney. An early histopathological lesion in the kidney was focal glomerulosclerosis. Moribund animals had diffuse glomerulosclerosis with prominent microcystic tubular dilatation, tubular epithelial degeneration, and interstitial nephritis. Electron microscopy revealed ultrastructural features consistent with the glomerulosclerosis: effacement of the foot processes of visceral epithelium and an increase in mesangial cell matrix. Transgenic mice variably expressed 6-, 4.3-, and 2-kb HIV-specific RNAs and HIV-related polypeptides in several tissues including kidney. Immunocytostaining revealed the presence of HIV-related protein in the glomeruli of affected animals. Glomerulopathy in these transgenic mice and HIV-associated nephropathy in man have similar features.

Animals↗
PubMed1991

Effect of cold ischemia time on the early outcome of human hepatic allografts preserved with UW solution.

Five hundred ninety-three cadaveric livers were used for primary liver transplantation between October 24, 1987, and May 19, 1989. The grafts were procured with a combined method, using in situ cooling with cold electrolyte solution and backtable flushing with UW solution. The mean cold-ischemia time was 12.8 (range 2.4-34.7) hr. The cases were divided into 5 groups according to the cold-ischemia time: group 1: less than 10 hr (n = 223); group 2: 10-14 hr (n = 188); group 3: 15-19 hr (n = 101); group 4: 20-24 hr (n = 52); and group 5: greater than or equal to 25 hr (n = 29). There was no difference between the 5 groups in 1-year patient survival, highest SGOT in first week after operation, and SGOT and total bilirubin during the first month after operation. However, with a logistic regression model, the retransplantation rate (P = 0.001) and primary nonfunction rate (P = 0.006) significantly rose as cold-ischemia time increased, meaning that the equivalency of patient survival was increasingly dependent on aggressive retransplantation.

Adenosine↗
PubMed1990

Natural killer cytotoxicity in the diagnosis of immune dysfunction: criteria for a reproducible assay.

Current evidence indicates that natural killer (NK) cells, which are large granular lymphocytes that mediate non-major histocompatibility complex (MHC)-restricted cytotoxicity and antibody-dependent cytotoxicity and that are involved in multiple regulatory, developmental, and immunologic processes, are important in health. Immunodeficiency states presenting with low NK activity are often associated with malignancies, chronic viral infections, or autoimmune diseases. Monitoring of NK function appears to be indicated as an aid to diagnosis, prognosis, and follow-up after therapy. Reliable performance of NK assays in a clinical laboratory requires that uniform criteria be established and followed for the acceptability of results. Statistical analysis of daily variability can be of great assistance in identifying and tracking sources of error, but routine statistical adjustments are not generally advisable. The quality control program described here provides a degree of assurance that this cytotoxicity assay can be dependable whether performed at one time point or serially. The successful implementation of this program requires laboratory resources, biostatistical support, and interpretative skills, all of which are available in a modern clinical laboratory.

Cytotoxicity Tests, Immunologic↗
PubMed1990

The role of handwashing in prevention of endemic intensive care unit infections.

Handwashing is believed to be the most important means of preventing nosocomial infections. Previous studies of healthcare workers (HCWs) have shown that handwashing practices are poor. No one has shown that handwashing practices can be easily improved and that this prevents endemic (nonepidemic) nosocomial infection. Handwashing and infection rates were studied in two intensive care units (ICUs) of a community teaching hospital. Handwashing rates were monitored secretly throughout the study. After six months of observation, we started interventions to increase handwashing. Handwashing increased gradually, but overall rates before (22.0%) and after (29.9%) interventions were not significantly different (p = .071). Handwashing never occurred before intravenous care, whereas it occurred 67.5% for all other indications (p less than .0001). When questioned, nurses felt they were washing appropriately nearly 90% of the time. Infection rates seemed unrelated to handwashing throughout the study, and no clusters of infection were detected. We conclude that handwashing rates, when measured against arbitrary but reasonable standards, are suboptimal, difficult to change and not closely related to evidence of cross-infection. Further, nurses wash hands selectively, depending on the indication for handwashing, and generally believe they are washing much more frequently than an objective observer believes they are.

Cross Infection↗
PubMed1990

Comparison of indirect immunofluorescent-antibody assay, enzyme-linked immunosorbent assay, and Western immunoblot for the diagnosis of Lyme disease in dogs.

Enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescent-antibody assay (IFA), and Western immunoblot were used to test serum samples from 128 dogs for the presence of antibody to Borrelia burgdorferi. Sera included 72 samples from dogs suspected of having Lyme disease, 32 samples from dogs residing in areas in which Lyme disease was not considered endemic, and 24 samples from dogs with clinical and serologic evidence of immune-mediated disease (n = 10), Rocky Mountain spotted fever (n = 5), or leptospirosis (n = 9). Results of Western immunoblotting were used as the standard against which performances of ELISA and IFA were measured. ELISA was significantly more sensitive than IFA (84.8 versus 66.7%), although both tests were equally specific (93.5%). Eight samples that were positive by Western immunoblot were simultaneously negative by ELISA and IFA. Of these eight, four were from dogs suspected of having immune-mediated disease, two were from dogs suspected of having leptospirosis, and two were from dogs suspected of having Lyme disease. These results may indicate that sera from dogs with immune-mediated disease, and to a lesser extent sera from those with leptospirosis, cross-react with B. burgdorferi antigens. Alternatively, Western immunoblot results may not truly reflect Lyme disease status, particularly in the case of dogs with immune-mediated diseases. At present, however, the use of Western immunoblotting as a diagnostic standard for dogs offers the best alternative to a clinical definition of disease.

Animals↗
PubMed1989

A study of familial hypercholesterolaemia in Iceland using RFLPs.

We have studied 17 unrelated families from Iceland who have familial hypercholesterolaemia (FH), using three different restriction fragment length polymorphisms (RFLPs) of the LDL receptor gene. In one family FH was caused by a 2 kb deletion in the LDL receptor gene in the region of exons 9 to 10. The PvuII (intron 15), NcoI (exon 18), and ApaLI (intron 15) RFLPs were used to determine the haplotypes associated with the defective LDL receptor gene in Iceland. Genotypes were determined in 77 subjects from these 17 families, both FH and non-FH. A rare new NcoI RFLP was detected in three subjects. Among the patients, at least four different haplotypes were observed indicating that FH in Iceland is caused by at least four different mutations and is a heterogeneous disease, even in the small, geographically isolated population of Iceland.

Adult↗