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Biomedical subjects

J A Gilbert

Publications and source records attributed to J A Gilbert.

At least 91 records · Page 5Linked to original sources
PubMed1982

Evidence for two classes of chromatin-associated Epstein-Barr virus-determined nuclear antigen.

A new class of Epstein-Barr virus nuclear antigen (EBNA) was identified by the complement fixation assay. This new species of EBNA is more tightly bound to chromatin and was termed class II EBNA, as opposed to the more weakly associated species, class I EBNA. Preparations of this new antigen(s) specifically reduced absorption with the titer of anti-EBNA antibodies as determined by the anticomplement immunofluorescence assay. Therefore, the complement fixation antigens (class II EBNA) appear to be related to the classical EBNA (class I EBNA). The class I EBNA was found to focus at the same pH (4.6) as the soluble antigen found in the cytosol. The class II EBNA differed from the class I EBNA with regard to its overall charge, molecular size, antigenicity, and affinity for chromatin. The class II EBNA appeared to be a basic protein, based on its apparent pI of 9.2 and its binding to cation-exchange resins. It differed from histones with regard to its molecular size (molecular weight between 60,000 and 70,000) and its elution from hydroxylapatite chromatography. Steps were taken to prevent proteolysis and artifacts in the immunological assays and in the overall charge estimation of the new antigen by nonspecific basic histone protein-acidic protein interactions. Both class I and class II EBNA were identified by radioimmunoelectrophoresis on two-dimensional polyacrylamide gels with pI values of 5.0 and 8.5, respectively, and a molecular weight range of 60,000 to 70,000 for both. A lower-molecular-weight antigen identified by molecular sieve chromatography appeared to be due to interference by histones in the immunoassays since it was not observed by the two-dimensional gel electrophoresis. Further characterization of this class II EBNA is in progress.

Antigens, Viral↗
PubMed1982

Dynamic body forces on axillary crutch walkers during swing-through gait.

By means of dynamic analysis and a series of experiments, peak dynamic forces on subjects ambulating with axillary crutches are evaluated. For swing-through times of about one second, the subjects needed to support from 1.1 to 3.4 times their body weight at their hands; but the horizontal loads at their axilla were much less, varying from 3 to 11 percent of body weight. Such data can be useful in selecting axillary crutches with sufficient padding at the axilla to minimize pressure on the sensitive nerves and blood vessels in this area; and in predetermining whether a patient is strong enough to use crutches, since he must support more than his own weight.

Biomechanical Phenomena↗
PubMed1971

Ethanol metabolism in various racial groups.

Eskimos and Indians, according to casual reports, take longer to sober up after an alcoholic debauch than do whites. We studied this apparent difference by administering ethanol to appropriate subjects and determining blood alcohol concentrations at intervals. We found the concentrations fell significantly faster in whites. Neither previous experience of alcohol nor general diet appeared to account for this difference, leaving genetic factors as the indicated cause.

Adult↗
PubMed1966

Primary carcinoma of the liver in Alberta.

A survey was made to determine the incidence and to elucidate the manifestations of primary carcinoma of the liver in Alberta. The findings were compared with other reported series. Ninety-six cases were identified: 69 hepatomas, 25 cholangiomas and two cholangiohepatomas. Seventy-four of the patients were male and 22 were female, a male preponderance of greater than 3:1. Ages ranged from 7 days to 92 years, but the majority of the patients (58%) were in the seventh and eighth decades. The incidence of associated cirrhosis (38.5%) was lower than that noted in most series.Hepatomegaly, abdominal pain, weight loss and ascites were the outstanding clinical features. Gastrointestinal hemorrhage was frequent and second only to hepatic failure as the immediate cause of death. An abdominal mass and pleural effusion occurred in higher frequency than that cited in the literature. Associated disorders included peptic ulceration and cholelithiasis.Surgical biopsy was superior to needle biopsy in establishing the diagnosis. Laboratory tests and routine radiographs may be of diagnostic aid.

Adenoma, Bile Duct↗
PubMed1966

Selection of students for admission to medical school: A two-class decision approach.

The validity coefficient alone does not communicate sufficient information to estimate the errors in decisions to accept or reject candidates. By means of probability theory, it is demonstrated how information concerning errors in decisions may be estimated. With estimates of the frequencies of correct and incorrect decisions and the costs of such decisions, a utility index was defined, for which a minimum was sought as a function of the entrance requirement. Under the analytic criterion defined for utility, it was possible to determine for a number of cost systems the entrance score which would, in the long run, reduce losses to a minimum. The application of the model is illustrated using empirical data and hypothetical cost systems. For these data entrance requirements were determined according to the criterion in addition to selection ratios and probabilities of success.

Aptitude Tests↗
PubMedDate not supplied

Vogt-Koyanagi-Harada syndrome: case report and review.

The case of an adolescent male with a painful red eye is presented, and the emergency department differential diagnosis is reviewed. The patient had Vogt-Koyanagi-Harada (VKH) syndrome, a panuveitis with extraocular systemic manifestations. The syndrome may result in permanent visual loss but is quite sensitive to corticosteroid therapy. Early ophthalmologic consultation from the emergency department is essential for prompt institution of definitive therapy and preservation of vision. The salient features and diagnostic evaluation of VKH are reviewed.

Adolescent↗
PubMedDate not supplied

The significance of transient changes in trabecular bone remodeling activation.

After menopause, bone turnover is increased due to an increase in the activation of bone remodeling basic multicellular units (BMUs). The importance of changes in BMU activation to bone histomorphometry data and bone volume has not received adequate attention by many skeletal researchers. Therefore, the influence of BMU activation on the above parameters was modeled by way of computer simulation, and the results were compared to data from published post-menopausal bone loss studies. Using control theory concepts, the increase in BMU activation after menopause was modeled as a zero-, first-, or underdamped (oscillatory) second-order transient BMU activation response to the step input: the decline in estrogen. A computer simulation was developed to model the influence of these three transient BMU activation responses on quantitative histological surface parameters and bone volume. The transient BMU activation responses doubled the number of active BMUs. All three types of transient BMU activation responses produced a rapid 5% decline in bone volume due to increased remodeling space. Oscillations in bone volume and histologic surface parameters over time, similar in nature to those seen in studies of ovariectomized animals, were predicted by the simulation for the oscillatory activation response examined, underdamped second order. An oscillatory BMU activation response may explain some of the transient events during menopause. The increased coherence of BMUs created by such a response may increase the likelihood of trabecular perforations. the inherent nature of an oscillatory activation response may cause its detection to be overlooked and bone remodeling data to be misinterpreted.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Fluid dynamics in man of an intraperitoneal drug delivery solution: 4% icodextrin.

Interest in targeting drugs into the peritoneal cavity for intra-abdominal cancers or infections is undergoing a revival as recent clinical trials have demonstrated, not only a regional advantage in concentration of the active agent, but also improved long-term outcomes. Solutions currently used for intraperitoneal (IP) drug delivery have short residence times, however, which can limit the exposure of all areas of the peritoneum to the active agent. Icodextrin 4% solution was compared with saline and a glucose-based peritoneal dialysis solution in a clinical study of IP residence time. The study was carried out during the fortnightly rest phase in 9 patients undergoing 5-fluorouracil (5-Fu) IP treatment for colorectal cancer. The volume remaining in the peritoneal cavity was measured at 0, 12, 24, 48, 72, and 96 hr after an instillation of 2 liters of each fluid. Saline (n = 3 dwells) and glucose (n = 3 dwells) peritoneal dialysis solutions were almost fully absorbed by 24 hr, and the patients experienced discomfort when using these solutions. In contrast, icodextrin 4% solution (n = 188 dwells) maintained its instilled volume for up to 48 hr, and half the instilled volume remained after 72 and 96 hr. This result would allow extensive and prolonged coverage of the peritoneal surface. Icodextrin 4% solution may be an effective vehicle to deliver therapeutic agents into the peritoneal cavity.

Aged↗
PubMedDate not supplied

Holding power of cortical screws after power tapping and hand tapping.

Paired equine third metacarpal bones were drilled and tapped for 4.5 mm and 5.5 mm cortical screws. Tapping was done by hand or with an air-driven reversible orthopedic drill. Screws were inserted and subjected to extraction forces to failure of the osseous threads or the screws. There was no difference in holding power of either screw size between hand-tapped and power-tapped holes.

Animals↗
PubMedDate not supplied

Assessment of the directional elastic moduli of ewe vertebral cancellous bone by vibrational testing.

The ovariectomized ewe is being used as an animal model for postmenopausal osteoporosis. Data on the mechanical properties of ewe vertebral cancellous bone is needed to assess its effectiveness as a model for vertebral osteoporosis. This study utilized traditional compression testing and a novel nondestructive vibrational testing method to assess the directional mechanical properties of ewe vertebral cancellous bone. Composition and density properties were also assessed. It was hypothesized that vibrational testing would have utility in that it would allow for the anisotropic stiffness of cancellous bone to be assessed nondestructively. The present study has found that ewe vertebral cancellous bone has similar physical and mechanical properties to humans. The vibrational testing method described was able to nondestructively provide a valid measure of stiffness that was correlated with stiffness estimates from traditional compression testing. Furthermore, the stiffness measure from the vibration test was found to be sensitive to the architecture of cancellous bone. These results suggest the promise of this testing method for the nondestructive mechanical assessment of skeletal tissue.

Animals↗