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Biomedical subjects

S Wilson

Publications and source records attributed to S Wilson.

At least 523 records · Page 29Linked to original sources
PubMed1983

Effect of pentobarbital on the strength duration curve of the jaw opening reflex to tooth pulp stimulation in cats.

Brain stem field potentials and digastric electromyographic responses to tooth pulp stimulation were recorded in six chronically prepared adult cats. Strength duration curves were derived for both responses under conditions of wakefulness and anesthetic levels of sodium pentobarbital (35 mg/kg). For the muscle response, the slope of the strength duration curve for short duration pulses became more negative, and the chronaxies were significantly increased under anesthesia as compared to the awake state. For the field potential response, the same parameters were not significantly altered. The results suggest that the alteration in strength duration curve seen in the muscle response may be determined beyond the level of the first synapse.

Animals↗
PubMed1983

In search of early pregnancy factor: isolation of active polypeptides from pregnant ewes' sera.

A four-step procedure is described for the isolation of the polypeptides which are responsible for a major portion of the EPF activity present in pregnant ewes' sera between 3-8 weeks gestation. The procedure utilises large-scale molecular size fractionation on hollow fibres in combination with conventional ion-exchange chromatography and HPLC gel permeation. It yields two homogeneous active fractions. One contains a single polypeptide of molecular weight approximately 20K, the other a 67K polypeptide. When compared on either a weight or molar basis the 20K polypeptide was at least an order of magnitude more active in the rosette inhibition test than the 67K polypeptide. The 20K polypeptide appears to represent the major form of RIT active material (EPF) present in pregnancy sera at this stage of gestation in the ewe.

Animals↗
PubMed1983

Glucose production and utilization in non-pregnant, pregnant and lactating ewes.

By using continuous infusions of 3H- and 14C-labelled substrates, three-pool models, incorporating rumen propionate, plasma glucose and blood carbon dioxide were constructed to determine the contribution of propionate to glucose in non-pregnant, pregnant (mid and late) and lactating hill ewes. Although the intakes of non-pregnant and pregnant ewes were the same (1200 g dried grass/d) and resulted in similar levels of propionate production (33 g C/d), glucose production rate (GPR) increased from 44 g C/d in the non-pregnant ewes to 62 g C/d in the ewes carrying twins in late pregnancy. In lactating ewes given 2500 g dried grass/d, propionate production increased to 56 g C/d and GPR increased to 93 and 104 g C/d in ewes suckling single and twin lambs respectively. There was an increase in the percentage of the propionate resource which was diverted to glucose, from 37% in the non-pregnant ewes and ewes in mid-pregnancy, to 55% in late pregnancy and 60% in lactation. In spite of this apparent metabolic adaptation to the additional requirements for glucose, approximately 55% of the glucose-C was supplied by metabolites other than propionate and CO2. From the determination of plasma glycerol concentrations it was estimated that the maximum possible contribution of glycerol-C to glucose was only 8-12 g C/d. The remaining 40% of the glucose-C could not be accounted for and could have been derived from non-essential amino acids (NEAA). In the non-pregnant and pregnant ewes only 62% of the GPR was oxidized to CO2. In the lactating ewes only 49 and 30% of the GPR was oxidized to CO2 in the ewes suckling single and twin lambs respectively. In the majority of cases there was a marked similarity between the amounts of glucose-C apparently derived from NEAA and the amount of glucose-C which was not oxidized to CO2.

Animals↗
PubMed1983

Acetylcholine receptor turnover in mice with passively transferred myasthenia gravis. I. Receptor degradation.

The in vivo degradation of endplate acetylcholine receptors was investigated in mice treated daily with IgG from 10 myasthenia gravis patients. Four preparations increased the rate of degradation. The number of endplate acetylcholine receptors after 7 days of IgG treatment was greater than that predicted on the basis of the increased degradation rate, suggesting a compensatory increase in receptor synthesis.

Adult↗
PubMed1983

Acetylcholine receptor turnover in mice with passively transferred myasthenia gravis. II. Receptor synthesis.

The in vivo synthesis of diaphragm endplate acetylcholine receptors was estimated in mice treated daily with IgG from eight myasthenia gravis patients. Myasthenia gravis IgG preparations which had previously been shown to increase the rate of receptor degradation also increased the rate of receptor synthesis, suggesting the existence of a compensatory mechanism serving to stabilise the number of acetylcholine receptors.

Animals↗
PubMed1983

Mirror-tracing and Embedded Figures tests as predictors of dental students' performance.

Recent studies of the Embedded Figures and Mirror-Tracing Tests as predictors of first-, second-, and third-year dental students' grades were extended to the fourth year, and the comparative utility of the experimental predictors were examined in groups of recent dental graduates categorized by their predental science GPAs and DAT scores. The experimental predictors proved to very strong in graduates whose grades were below average at admission and were the best overall predictors for students who entered dental school with a predental science GPA below 3.0 or a combined DAT score below 4.0. Neither the DATs nor the predental science GPAs contributed consistently as predictors in these below average students. However, the predental science GPA was the best single overall predictor for all graduates (when not categorized as described). the experimental predictors contributed significantly to the predictive utility of the predental science GPA.

Aptitude Tests↗
PubMed1983

Correlation between initial and long-term responses of spontaneous pet animal tumors to heat and radiation or radiation alone.

Most early-phase testing of new therapeutic modalities involves analysis of initial tumor response as opposed to estimation of long-term response. In this study, the validity of initial response rates to predict long-term responses was examined for tumors treated with radiotherapy alone compared with heat combined with radiotherapy. A total of 130 pet animals with either squamous cell carcinomas, melanomas, fibrosarcomas, mammary adenocarcinomas, or mast cell sarcomas were randomized to receive either radiation alone (XRT) or heat + radiation (delta + XRT). Responses to treatment were evaluated by response rates and response duration. The complete response (CR) rates were consistently higher for delta + XRT than for XRT across different histology groups. The combined therapy led to prolonged tumor response in all histological subgroups except melanomas, which had a longer response duration when treated with XRT alone (p = 0.043). This was in spite of a relatively high CR rate in that group (100% versus 12.5% for delta + XRT and XRT, respectively). In contrast, while no significant improvement in CR rate was observed for dermal squamous cell carcinomas treated with delta + XRT (XRT = 52.9%; delta + XRT = 68.8%), a significant improvement in response duration was noted (p = 0.002). These are two examples where CR rate did not predict long-term response. When all histological subgroups were combined (except melanomas), the CR rate was higher (p less than 0.001), and response duration was prolonged (p = 0.031) for delta + XRT compared to XRT alone.

Animals↗
PubMed1982

Pyogenic liver abscesses: successful non-surgical therapy.

Eleven consecutive patients with pyogenic liver abscesses were seen in a 20-month study period. Ten patients were treated with antibiotics alone. All ten had abscesses demonstrated by hepatic scintigraphy or sonography. In six patients purulent material was obtained by percutaneous aspiration of the liver. Blood-cultures were positive in each of the nine patients in whom they were obtained. Nine of the ten patients treated with antibiotics alone were cured; one died from complications of a liver biopsy. These results indicate that pyogenic liver abscesses can be effectively managed by medical therapy and that surgery is rarely required.

Adult↗
PubMed1982

Actin in human spermatozoa.

An actin-like material was extracted from human spermatozoa. The material comigrated with actin on sodium dodecylsulfate (SDS) polyacrylamide gel electrophoresis, and showed specific affinity for myosin. Purified anti-actin antibodies were used to localize actin to the posterior region of the sperm head and to the connecting piece, midpiece and mainpiece of the tail. Determination of the function of sperm actin requires further investigation.

Actins↗
PubMed1982

Toy play, play tempo, and reaction to frustration in infants.

Measures of toy play including duration and tempo of play were obtained for a combined sample of 7 male and 5 female infants 22 to 26 mo. of age. Additional measures of reaction to frustration were obtained during a second session where toys were placed out of reach of the subjects. Measures of frustration included crying, squirm/escape attempts, and non-crying vocalizations. Several correlations between toy play and reaction to frustration were found and were indicative of a general relationship between response persistence during play and attempts to escape from the frustrating situation.

Attention↗
PubMed1982

Field dependence-independence and dental students' clinical performance.

The construct of field dependence-independence (FDI) is a bipolar characterization of cognitive style and functioning that has achieved wide interest outside the field of dental education. Since dental educators lack effective preadmission predictors of clinical grades or performance, the authors examined two tests of FDI as potential new predictors. The Embedded Figures Test (EFT) is a recognized FDI descriptor test based on the ability to identify rapidly and accurately a series of simple geometric figures "embedded" in more complex figures; such performance is characteristic of the field-independent individual. Similarly, rapid and accurate performance on the Inverted Tracing Test (ITT) (mirror tracing of simple figures) may also be characteristic of the field-independent individual. Multiple regression analyses indicated that the EFT and ITT parameters correlated more closely with clinical grades that did Dental Admission Test (DAT) predictors. The results suggest that individuals who tend to be field-independent, rather than field-dependent may hav an advantage in the dental school's clinical curriculum.

Clinical Competence↗
PubMed1981

A method for culturing canine tracheal smooth muscle cells in vitro: morphologic and pharmacologic observations.

A method of culturing canine tracheal smooth muscle cells in vitro is described. The morphology of these cells is monitored up to 60 days in culture and selected stages are illustrated. The characteristics of these cells are numerous mechanical attachments, the presence of thick filaments in suitably processed cells, and their contractile response to in vitro administration of carbachol, a cholinomimetic drug. They also possess nexus formations and both thin (actin) filaments and 10-nm filaments. Mitosis is found in the nonconfluent preparations up to 16 days after culturing. Cultures of 2 to 8 days appear to be most useful as pharmacological test vehicles. This system will be used to explore the phenomenon of adrenergic beta-2 receptor desensitization in airway smooth muscle, to attempt to localize these receptor sites and to determine how receptor affinity and/or number may be regulating cell response to pharmacologic agents.

Animals↗
PubMed1981

Sympathetic activation of brown-adipose-tissue thermogenesis in cachexia.

Tumour-bearing mice spontaneously lose weight 8-9 weeks after implantation of a human hypernephroma, in spite of a normal food intake. Resting oxygen consumption was up to 40% higher in these animals than in sham-operated controls, but was significantly reduced by beta-adrenergic blockade with propranolol in the former group. The injection of noradrenaline caused a marked stimulation of the metabolic rate in all the animals, but the greatest response was seen in the cachectic mice. The brown-adipose-tissue mass was similar for both groups, but guanosine diphosphate binding to brown-adipose-tissue mitochondria (an index of thermogenic capacity) was significantly increased in tumor-bearing mice, and the injection of noradrenaline 1 h prior to sacrifice caused the greatest stimulation of binding in the cachectic group. These data suggest that the rapid weight loss of tumor-bearing animals may be due to a high metabolic rate which results from sympathetic stimulation of brown-adipose-tissue metabolism. The relevance of these results to cancer-induced cachexia in man is discussed.

Adipose Tissue, Brown↗
PubMed1981

Inability to detect hepatitis B surface antigen (HBsAg) in the duodenum of HBsAg-positive persons.

Incubation of hepatitis B surface antigen (HBsAg)-positive serum with duodenal fluid (DF) of normal persons results in marked reduction of immunoreactivity. This was shown to be caused by: (1) interference with radioimmunoassay (RIA) system and (2) actual destruction of HBsAg. The interference in the RIA system could be counteracted by addition of bovine serum and a reproducible detection system of HBsAg in DF was established. DF of HBsAg-positive persons was negative for HBsAg. One HBsAg carrier who had a partial pancreatectomy for an insulinoma had separate cannulae in his bile and pancreatic ducts. Whereas HBsAg could be detected in bile, it was undetectable in pancreatic juice. Incubation of his pancreatic juice with his bile resulted in disappearance of HBsAg. It appears that a factor present in pancreatic juice, or resulting from the interaction of pancreatic juice and bile, results in disappearance of HBsAg immunoreactivity.

Bile↗
PubMed1981

Idiopathic pelvic fibrosis: a variant of retroperitoneal fibrosis?

The management of 2 cases of a rare condition previously labelled idiopathic pelvic fibrosis is described. Two cases reported previously are reviewed. The unusual histologic and radiologic features are emphasized, and the differences between this condition and idiopathic retroperitoneal fibrosis are summarized. Etiologic features, including the possible role of previous pelvic infection, drug-induced hypersensitivity and autoimmunity, are discussed. We believe that disease originating in the vas may be the source of this unusual fibrotic process.

Adult↗