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Biomedical subjects

B Buchanan

Publications and source records attributed to B Buchanan.

At least 19 recordsLinked to original sources
PubMed2000

Statistical methods for the objective design of screening procedures for macromolecular crystallization.

The crystallization of a new macromolecule is still very much a trial-and-error process. As is well known, it requires the search of a large parameter space of experimental settings to find the relatively few idiosyncratic conditions that lead to diffraction-quality crystals. Crystallographers have developed a variety of screens to help identify initial crystallization conditions, including those based on systematic grids, incomplete factorial and sparse-matrix approaches. These are somewhat subjectively formulated based on accumulated data from past crystallization experiments. Ideally, one would prefer as objective a procedure as possible; however, that requires objective methods that incorporate a broad source of crystallization data. The Biological Macromolecular Crystallization Database (BMCD), a repository of all published crystallization conditions, is an obvious source of this data. This database has been augmented with a hierarchical classification of the macromolecules contained in the BMCD as well as extensive data on the additives used with them. A statistical analysis of the augmented BMCD shows the existence of significant correlations between families of macromolecules and the experimental conditions under which they crystallize. This in turn leads to a Bayesian technique for determining the probability of success of a set of experimental conditions based on the data in the BMCD as well as facts about a macromolecule known prior to crystallization. This has been incorporated into software that enables users to rank experimental conditions for new macromolecules generated by a dense partial factorial design. Finally, an additional advantage of the software described here is that it also facilitates the accumulation of the data required for improving the accuracy of estimation of the probabilities of success - knowledge of the conditions which lead to failure of crystallization.

Crystallization↗
PubMed1993

Intestinal colonization of young chicks with Escherichia coli O157:H7 and other verotoxin-producing serotypes.

The susceptibility of chicks to colonization with Escherichia coli O157:H7 and other verotoxin-producing serotypes was studied. The E. coli colonized the caeca of both broilers and layers after oral administration of the challenge. The extent of colonization was dependent on challenge dose, age of chicks at the time of challenge, breed of chicks and length of time after exposure. A rapid increase in caecal colonization and a decrease in crop colonization was evident during the first few hours after challenge, with a maximum in the caeca at 6 h. Escherichia coli persisted in caecal contents as well as on caecal walls throughout the course of the experiments (14 d), but at much lower levels compared with the 6 h post-challenge.

Aging↗
PubMed1993

Performance of the "house doctor". Effect of physician-to-patient ratio on follow up in long-term care facilities.

Do physicians with many patients in a long-term care facility provide more timely follow up of their drug orders than those with only a few? We reviewed 60 charts at random in three intermediate care facilities. Physician practices fell into two distinct groups. Those with more than 17 patients followed up sooner than those with fewer than six. We recommend a "house doctor" model of care for patients whose follow up is poor.

British Columbia↗
PubMed1992

Comparison of a competitive enzyme immunoassay kit and the infant mouse assay for detecting Escherichia coli heat-stable enterotoxin.

A commercial competitive enzyme immunoassay kit, Escherichia coli ST EIA, was compared with the conventional infant mouse assay for sensitivity and specificity in detecting E. coli heat-stable enterotoxin. Thirty-one of 46 strains of E. coli tested were positive by both assays, while 15 strains were negative. The sensitivity of the ST EIA kit was up to 64-fold lower than the infant mouse assay.

Animals↗
PubMed1991

Age effects susceptibility to pulmonary barotrauma in rabbits.

OBJECTIVE: We studied the effect of age on the development of pulmonary barotrauma after mechanical ventilation with high peak inspiratory pressures (PIP). DESIGN: Young (4 to 6 wk old) and adult rabbits were ventilated for 1 hr at PIPs of 15, 30, and either 45 cm H2O (young group) or 55 cm H2O (adult group). MEASUREMENTS AND MAIN RESULTS: The pulmonary capillary filtration coefficient (Kf,c) was measured in an isolated lung perfusion system after the animals were killed. In young rabbits, Kf,c increased significantly from the 15 cm H2O PIP value in both the 30 cm H2O (55%) and 45 cm H2O (507%) PIP groups, whereas Kf,c was increased in adult rabbits only in the 55 cm H2O (113%) PIP group. Kf,c was significantly (p less than .01) higher in young rabbits than in adult rabbits after ventilation, with every level of PIP being 91% higher at 15 cm H2O PIP and 440% higher at 45 to 55 cm H2O PIP. Also, a greater incidence of pneumothorax and airleaks was observed in the young rabbits. Pressure-volume loops demonstrated that the young rabbits had more compliant lungs and chest wall than adult rabbits. CONCLUSIONS: These data indicate that the lungs of young rabbits had a higher baseline microvascular permeability and were more susceptible to the development of ventilator-induced increased microvascular permeability. More compliant lungs and chest wall and the larger distending volumes attained at each peak airway pressure appear to be the mechanisms.

Aging↗
PubMed1991

Assessment of two commercial agglutination kits for detecting Escherichia coli heat-labile enterotoxin.

Two commercial agglutination kits, a reserved passive agglutination test (VET-RPLA) and a staphylococcal coagglutination test (Phadebact ETEC-LT Test), were compared with two cell culture assays (Y-1 and Vero) and GM1 ganglioside enzyme-linked immunosorbent assay (GM1-ELISA) for sensitivity in detecting Escherichia coli heat-labile enterotoxin (LT). Of 48 toxigenic strains, 23 were positive by all assays. One strain was negative only by the Phadebact test. Four strains, all LT-II producers, were positive by cell culture only. For LT-I detection, the Phadebact test was the least sensitive but was simple and rapid; VET-RPLA was simple, sensitive, and a good substitute for cell culture or GM1-ELISA.

Agglutination Tests↗
PubMed1990

The sky is not falling.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Effective management strategy for establishing an operating room satellite pharmacy.

The steps involved in justifying and implementing an operating room (OR) pharmacy satellite are described. A hospital administrator's viewpoint on the project is included. Objectives of the satellite were to reduce inventory costs, improve control of distribution, reduce loss of revenue and improve patient charging, improve IV compounding and labeling, and significantly improve narcotic control and accountability. The satellite provides comprehensive services 12 hours a day, five days a week. Effective after-hours procedures have been developed to provide efficient drug distribution when the pharmacy is closed. Achieved benefits of the satellite include decreased drug inventory, improved patient charging, accurate labeling, improved IV compounding, and improved pharmacy/surgery relations. The OR pharmacy satellite is a successful cost-effective operation.

Centralized Hospital Services↗
PubMed1987

Modification of glycogen deposition by priming glucose loads: the second-meal phenomenon.

Glucose priming modifies tolerance and oxidation of subsequent loads. To assess effects in glycogenesis, rats were given a D-[U14C]-glucose load, either alone or preceded by one or two unlabeled hourly doses. The incorporation of 14C into total liver glycogen was 8.6 +/- 0.4% of the glucose dose and was little changed by priming loads. Total liver glycogen was 169 +/- 10 mg after one load and 276 +/- 12 mg after two; after three it fell to 243 +/- 20 mg. In muscle, net incorporation of 14C was 9.6 +/- 0.6% of the first but fell to 6.9 +/- 0.4% of the third glucose 14C dose/100 g. Muscle glycogen concentration rose at a decremental rate with priming. Net incorporation of glucose 14C into hepatic glycogen remains constant after repeated loads even after storage is reduced. In keeping with the reported peripheral resistance to glucose uptake in the second-meal phenomenon, repeated loading is associated with reduction of 14C-glucose incorporation into muscle glycogen.

Animals↗
PubMed1984

Potentiation of 14C-glucose oxidation by priming glucose loads: effect of starvation.

The mechanism of the Staub-Traugott effect or facilitated glucose disposal after successive glucose loads has remained elusive. In earlier publications, we have shown it can be independent of circulating hormone and free fatty acid levels. We have also proposed that it might partially depend on the rapid induction of glycolytic pathways, which are known to be depressed by prolonged fast. Mature rats were given 1.75 gm/kg glucose doses intravenously at 60-minute intervals. Respiratory CO2 was collected at 15-minute intervals over a 120-minute period following administration of the carrier glucose plus 6 microCi/100 gm rat weight of 14C-D-glucose, given either as the first, second, or third challenge. In rats fasted 14 hours there was potentiation of labeled CO2 recovered after each successive load. After three days of starvation, both relative 14C-glucose oxidation to 14CO2 as well as absolute 14CO2 increments after each load were lower. The changes in relative oxidation of an intravenous glucose load might partly account for the facilitated disposal of blood glucose seen in the second and third hours in overnight-fasted rats (Staub-Traugott effect). However, although rats fasted for three days had suppressed the Staub effect, the increments in oxidation were attenuated but still present, suggesting that alterations of other pathways must participate in the disappearance of this effect after fasting.

Animals↗
PubMed1978

A comparative study of five commercial reagents for the Coulter Model S: a proposed method for reagent evaluation.

A comparative study of five competitive commercial reagents for the Coulter Model S was performed jointly by two large, busy hospital laboratories with active quality control programs. Both laboratories, independently using the same reagent systems, studied 20 consecutive blood samples from patients from their own respective hospital for 20 days. Data from both laboratories were analyzed by standard and nonstandard statistical methods, and the results from both laboratories were compared. Although all reagent systems performed reasonably well in a clinical setting, highly significant statistical differences in their precisions were demonstrated by using univariate and multivariate techniques. The statistical method developed in this study can be applied to other systematic investigations that compare reagent systems.

Blood Cell Count↗