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Biomedical subjects

D Allen

Publications and source records attributed to D Allen.

At least 163 records · Page 9Linked to original sources
PubMed1991

Intracranial trauma associated with extraction of a temporal ear tooth (dentigerous cyst) in a horse.

Heterotopic polyodontia is typically associated with a sinus and a fistulous tract with a secreting membrane which extends to an ectopic tooth attached to the temporal bone. Recommendations for treatment include complete excision of the tract, the dental component, and the lining of the alveolar socket. Iatrogenic cerebral trauma was encountered during surgical extraction of an ectopic tooth. At post-mortem examination a second ectopic tooth was found compressing the right side of the cerebellum.

Animals↗
PubMed1990

Dose-response profiles of plasma growth hormone and vasopressin after clonidine challenge in man.

The objective of the study was to determine dose-response relationships of growth hormone, vasopressin, blood pressure, heart rate, and behavioral responses to clonidine. Ten healthy male volunteers were tested with each of three doses of clonidine (0.7, 1.4, and 2.1 micrograms/kg) with at least 1 week between tests. All doses gave a significant growth hormone response with a peak at 50 min. The high dose gave a significantly higher response than either the medium dose or the low dose, which did not differ from each other. Within individual subjects, there was a consistency of response to the different doses; thus, three of the volunteers had responses of 5 ng/ml or higher to the low dose. Those three subjects had higher growth hormone peaks after the highest dose than did six other subjects. Vasopressin showed a drop following clonidine after the two higher doses. Systolic blood pressure dropped following clonidine, showing a significantly greater drop for the medium and high doses than for the low dose. Diastolic blood pressure also showed a drop, but responsiveness did not differ between doses. There was significant dryness of mouth produced by clonidine, but no difference between doses. There was a significant sedative effect following clonidine which was greater for the high dose than for the medium or low dose. The finding that some subjects had a growth hormone peak of 5 ng/ml or greater after the low dose supports the hypothesis that use of a low dose strategy may be useful in confirming supersensitivity in conditions where increased responsiveness is suspected. The lack of difference between blood pressure responses to the medium and high doses of clonidine--doses that have different effects on growth hormone--supports the hypothesis that differences in responsiveness of presynaptic and postsynaptic alpha 2-adrenergic receptors exist.

Adult↗
PubMed1990

Gene amplification on chromosome band 11q13 and oestrogen receptor status in breast cancer.

We have analysed DNA from 183 primary breast cancers for amplification or rearrangement of a number of cellular proto-oncogenes, focusing primarily on a cluster of markers on the long arm of chromosome 11. Two of these oncogenes, INT2 and HST1, both of which encode members of the fibroblast growth factor family, are implicated in the generation of virally induced mammary tumours in mice. Here we confirm earlier reports that the q13 region of chromosome 11, in which these genes are tandemly linked, is modestly amplified in approximately 15% of primary human breast cancers. This amplification is confined, with one exception, to cases in which the oestrogen receptor (ER) levels are in excess of 20 fmol/mg protein (P = 0.001). However, DNA amplification does not usually result in detectable expression of either the INT2 or HST1 gene. The data imply that some other gene in the vicinity must contribute to the development of a subset of ER-positive tumours and that assessing the amplification of this region of DNA may be of value in defining a separate category of ER-positive tumour.

Adult↗
PubMed1990

DNA index, S-phase fraction, histological grade and prognosis in breast cancer.

DNA index and S-phase fraction (SPF) were measured by flow cytometry on paraffin embedded tissue from 140 primary breast tumours. The results of DNA analysis were compared with the size, degree of axillary node involvement, histological grade and steroid receptor content of the tumours, as well as with the patients' subsequent clinical course. Forty-four (31.4%) of the 140 tumours were diploid. S-phase fraction was evaluable for 134 (95.7%). The median SPF of the whole population was 7.1%, with diploid tumours having a significantly lower median SPF (3.2%) than aneuploid (10.1%, P less than 0.001). Both aneuploidy (P = 0.002) and high SPF (P less than 0.001) were strongly associated with high histological grade. There was no significant association between either DNA ploidy or SPF and tumour size, nodal status or steroid receptor content. An SPF below the median was strongly associated with better relapse-free survival (P = 0.008), overall survival (P = 0.004) and survival after relapse (P less than 0.001). Ploidy did not correlate significantly with clinical course. Multivariate analysis using the Cox model suggested that, while SPF gave prognostic information independent of tumour size or nodal status, this independent significance was lost when histological grade was included in the analysis.

Adult↗
PubMed1990

Evaluation of a special behaviour unit for people with mental handicaps and challenging behaviour.

A descriptive evaluation is provided of a hospital-based unit for people with mental handicaps and challenging behaviours. The characteristics of clients admitted to the unit over a 15-month period are described, together with admission and discharge patterns, and treatment interventions undertaken. The progress of four clients is studied in detail via single-case studies. While reductions in levels of challenging behaviour occurred during admission, these changes were not generally maintained at follow-up. Implications for future service design are discussed.

Adult↗
PubMed1990

Day hospital care.

Explore the source record for details and available documents.

Consumer Behavior↗
PubMed1990

Evaluation of equine digital Starling forces and hemodynamics during early laminitis.

A carbohydrate overload model was used in 8 horses to evaluate Starling forces and hemodynamics of the digit during the prodromal stage of acute laminitis. A pump-perfused extracorporeal digital preparation was used to evaluate blood flow, arterial pressure, venous pressure, capillary pressure, isogravimetric capillary filtration coefficient, osmotic reflection coefficient, and vascular compliance. From these data, pre- and postcapillary resistances and pre- to postcapillary resistance ratios were determined. Vascular and tissue oncotic pressures were estimated from plasma and lymph protein concentrations, respectively. The osmotic reflection coefficient, an estimation of capillary permeability, was determined by means of the lymph protein wash-down technique. Using the collected data, tissue pressure in the digit was calculated by use of the Starling equation. In the isolated digit, mean isogravimetric capillary pressure was 55.13 mm of Hg, mean plasma and lymph oncotic pressures were 22.29 mm of Hg and 7.2 mm of Hg, respectively, the mean osmotic reflection coefficient was 0.66, the mean capillary filtration coefficient was 0.003 ml/min/mm of Hg/100 g, and mean interstitial fluid pressure was 44.82 mm of Hg. The high capillary pressure appeared to be caused by high vascular resistance from the venous side, predisposing to enhanced capillary filtration and interstitial fluid accumulation.

Animals↗
PubMed1990

Evaluation of coagulation and fibrinolysis during the prodromal stages of carbohydrate-induced acute laminitis in horses.

The balance of coagulation and fibrinolysis was studied in 15 horses during the prodromal stages of acute laminitis induced by carbohydrate overload. Progression of the disease was stopped 12 to 24 hours before the expected onset of lameness in trial 1 (8 horses) and at the onset of lameness in trial 2 (7 horses). The end points in each trial were identified by specific changes in blood pressures (trial 1) and by changes in pulse, rectal temperature, and arterial pressure (trial 2) that were anticipated on the basis of original description of the experimental model. Blood samples for hemostasis evaluation were collected before and after carbohydrate overload in trial 1 and after carbohydrate overload in trial 2. Significant changes were not detected in platelet count, mean platelet volume, prothrombin time, activated partial thromboplastin time, fibrinogen concentration, plasminogen concentration, alpha-2-antiplasmin, antithrombin III, protein C, thromboxane B2, or fibrin(ogen) degradation product concentration. We concluded that an imbalance in coagulation and fibrinolysis is not pathogenic in the onset of experimentally induced equine acute laminitis. Because several test methods used to evaluate hemostasis in these horses were new, reference values for 34 healthy adult horses were established.

Animals↗
PubMed1990

Effect of endotoxin administration on equine digital hemodynamics and starling forces.

Using a pump-perfused extracorporeal isolated digital preparation, the effects of a 30-minute infusion of either saline solution (control) or endotoxin on equine digital hemodynamics and microvascular function were determined. Digital blood flow and arterial, venous, and capillary pressures were recorded at 15-minute intervals for 150 minutes. From these data, total vascular resistance and pre- and postcapillary resistances were calculated. Isogravimetric capillary filtration coefficient, vascular compliance, and the osmotic reflection coefficient were determined after the last hemodynamic measurements were taken. Changes in hemodynamic values of control equine digits were not observed. During the 120 minutes after infusion of endotoxin, digital blood flow decreased 43%, and total vascular resistance increased 89%. Precapillary resistance increased 122%, but postcapillary resistance did not change significantly. Changes in vascular compliance or the capillary filtration coefficient were not observed in response to either treatment. The osmotic reflection coefficient, an index of permeability, did not differ significantly between digits of the endotoxin-treated and control groups. These data indicate that the increase in vascular resistance during endotoxemia may have been attributable to arterial/arteriolar constriction and that neither the permeability nor the surface area of the exchange vasculature within the digit was significantly affected by endotoxin. Although marked alterations in vascular function are seen after administration of endotoxin, these changes do not parallel those documented in association with experimentally induced laminitis.

Animals↗
PubMed1990

Hemodynamic responses of the equine digit to intravenous and digital arterial infusion of dopamine.

In 6 adult horses anesthetized with pentobarbital, the hemodynamic responses of the equine digit to infusion of dopamine were evaluated by use of an isolated extra corporeal pump perfused digital preparation. Digital blood flow was maintained at a constant rate that was independent of systemic hemodynamic changes. Three sequential experiments were performed on each horse. In the first experiment (n = 6), dopamine was infused IV at rates of 1.0, 2.5, and 5.0 micrograms/kg/min. For the second experiment (n = 5), dopamine (400 micrograms/ml) was infused into the digital artery at the rates of 0.07, 0.7, and 1.2 ml/min. The third experiment (n = 5) consisted of a 5-minute intra-arterial infusion of phentolamine followed by the intra-arterial infusion of dopamine while continuing the infusion of phentolamine. Digital venous, arterial, and capillary pressures, total digital vascular resistance, and precapillary to postcapillary resistance ratios were determined in each experiment. Systemic infusion of dopamine did not induce changes in the hemodynamics of the digital vasculature. Digital arterial infusion of dopamine alone resulted in a dose-dependent increase in arterial pressure, total digital vascular resistance, and an increase in the precapillary to postcapillary resistance ratio. Phentolamine attenuated the vasoconstrictive response elicited by intra-arterial infusion of dopamine.

Animals↗
PubMed1989

The interaction between Cu(I) superoxide dismutase and hydrogen peroxide.

The interaction between superoxide dismutase (SOD) and peroxide, under anaerobic conditions in the presence of an OH radical scavenger, formate, and an indicator, nitro blue tetrazolium, involves five reactions and an equilibrium: (table; see text) Reaction 3 occurs at a rate that is proportional to both peroxide and enzyme with no kinetic evidence for any intermediate peroxide-enzyme complex. Rate studies as a function of pH corroborate previously published work (Fuchs, H. J. R., and Borders, C. L., Jr. (1983) Biochem Biophys. Res. Commun. 116, 1107-1113; Blech, D. M., and Borders, C. L., Jr. (1983) Arch. Biochem. Biophys. 224, 579-586) suggesting that HO2-, and not H2O2, is the active species in this system: k(HO2- + superoxide dismutase-Cu+) = 2.6 x 10(3) M-1 s-1. Evidence is presented which suggests that HO2-, like O2-, reacts at rates that are affected by the electrostatic forces of the enzyme.

Hydrogen Peroxide↗