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Biomedical subjects

R Davidson

Publications and source records attributed to R Davidson.

At least 91 records · Page 5Linked to original sources
PubMed1983

Cast brace management of the femoral shaft fracture in children and young adults.

Seventy-two children and adolescents, 5-19 years of age, sustaining femoral fractures were treated with immediate cast bracing at Oklahoma Children's Memorial Hospital. Ambulation was started an average of 3 days after fracture when there were no associated injuries. The average length of hospitalization was 18.7 days; the average length of immobilization in plaster was 67.4 days. Results were generally comparable to those of more standard methods of treating a fractured femur in this age group. Proximal as well as middle and distal fractures were treated, but varus and anterior angulation was not well controlled in proximal fractures. No patient had a clinically significant deformity. Sixty-one percent of the entire group healed with less than 6 mm discrepancy. Middle-third fractures showed more tendency toward shortening. All six fractures that healed with more than 1.5 cm of shortening were middle third. No injured femur was longer than the uninjured femur at a 6-month follow-up. Immediate cast bracing can provide an opportunity for early ambulation and avoid the sequelae of immobilization. Weekly assessment for the first 4 weeks is mandatory to monitor length and angulation. The adolescent male with a midshaft fracture was most difficult to manage, and in this situation, closed intramedullary nailing is recommended.

Adolescent↗
PubMed1980

The need for power, brain norepinephrine turnover and learning.

This experiment was designed to explore whether brain norepinephrine (NE) serves as a specific reward system for the power drive. Previous research has indicated that 3-methoxy-4-hydroxyphenyl glycol (MHPG), a urinary metabolite reflecting central NE turnover, is positively correlated with features of assertiveness which one might expect of a person high in the need for power (n power) or in a state of aroused power motivation. Twenty-seven male undergraduates, 13 of whom were high and 14 of whom were low in n power as assessed by a TAT measure, were recruited as subjects. Before and after the laboratory session, subjects voided all urine and concentrations of epinephrine, norepinephrine and MHPG were obtained from samples. The laboratory task consisted of 20 picture-word pairs in which the subject had to learn to anticipate the word associated with each picture before the word was presented. Five pairs of stimuli in each of the following picture-word combinations were presented 12 times: neutral-neutral, neutral-power, power-neutral and power-power. The results revealed that, as predicted, subjects high in n power learn most power-related material faster than subjects low in n power. The need for achievement is unrelated to the learning of any picture-word pairs. The neurochemical data indicated that subjects maintaining a relatively high MHPG excretion rate during the experiment who were also high in n power showed the greatest mastery of power related compared with neutral picture-word pairs. These findings are consistent with the hypothesis that brain NE turnover is specifically related to the learning of power-related responses in subjects high in n power.

Assertiveness↗
PubMed1980

Autosensitization and immune complexes in chronic idiopathic thrombocytopenic purpura.

Argument exists as to whether platelet damage in chronic idiopathic thrombocytopenic purpura (ITP) is mediated by an autoimmune response to platelet antigen or by immune complexes. We have studied thirty-nine patients with ITP for evidence of (i) sensitization to platelet antigen, using a macrophage migration inhibition factor (MIF) assay, (ii) circulating immune complexes, using a Clq deviation technique, and (iii) serum-induced platelet 'immunoinjury', using a 3H-serotonin release assay. Eighty-one per cent of the patient group had a migration index of less than 0.8 (normal range 0.8-1.3), while 91% of those tested had a serum factor (presumably immune complexes) which bound to labelled Clq. The serotonin release assay was abnormal in 32% of twenty-two patients, and the results of this test bore no clear relationship to either those of the Clq deviation test or the MIF results. We conclude that most patients with ITP are sensitized to platelet-associated antigen, and have circulating immune complexes. The contribution of these factors to platelet destruction and the nature of the antigen in the complexes remain to be demonstrated. The serotonin release assay is less sensitive, non-specific, and has limited value in the diagnosis of ITP.

Antigen-Antibody Complex↗
PubMed1980

Meningitis, ventriculitis, and hydrocephalus: a complication of fetal monitoring.

A case is presented of meningitis, ventriculitis, and hydrocephalus secondary to the use of fetal scalp monitoring. The most commonly reported fetal complication related to the application of the scalp electrode is the development of a scalp abscess; the incidence varies between 0.45 and 4.5%, but several other complications have also been reported and the overall incidence is not well established. Infants in whom a scalp electrode has been used should be carefully examined to detect potential serious complications.

Adolescent↗
PubMed1978

Casualty room presentations and schoolboy rugby union.

For eight years a casualty station has been operating during competition Rugby Union matches at a large Sydney School. During this time, both diagnosis and treatment have been recorded for every presentation. The casualty station was attended by 556 boys over this period, and approximately 50% of these presentations were for trivial injuries. Forty-three severe injuries occurred, of which most were fractures. The rate of presentation, and the pattern of injury, changed as a greater number of both minor and major injuries than did visitors. There was one injury in boys less than 12 years old, and the greatest incidence of injury was in boys aged from 16 to 18 years. It is concluded that there is a place for casualty services at schoolboy competition games, and that the supervised Rugby Union played in this and comparative school competitions is a reasonably safe game for boys less than 16 years old, to whom issues of schoolboy participation are most applicable.

Adolescent↗
PubMed1978

Defect in biosynthesis of the linkage unit between peptidoglycan and teichoic acid in a bacteriophage-resistant mutant of Staphylococcus aureus.

The biosynthesis of the linkage region between peptidoglycan and the ribitol teichoic acid was investigated in the bacteriophage-resistant, teichoic acid-less mutant Staphylococcus aureus 52A5 (Chatterjee et al., J. Bacteriol. 100:846--853, 1969). Membrane preparations of this strain were found to be incapable of forming the first intermediate of the biosynthetic pathway, namely, the transfer of N-acetyl-D-glucosamine (GlcNAc) from UDP-GlcNAc to the acceptor molecule, which presumbably is undecaprenol phosphate (R. Bracha and L. Glaser, Biochem. Biophys. Res. Commun. 72:1091--1098, 1976). The addition of heat-inactivated membrane preparations of S. aureus 52A2 (which normally has ribitol teichoic acid) that had been preincubated with UDP-GlcNAc to membranes of strain 52A5 enabled the synthesis of teichoic acid. These data suggest that the mutational defect in the teichoic acid-less organism is in the synthesis of the first compound of the linkage unit, and this is apparently the reason for its absence in the cell walls.

Cell Wall↗
PubMed1975

Aspergillus oryzae acid proteinase. Purification and properties, and formation of pi-chymotrypsin.

An acid proteinase from Aspergillus oryzae was isolated from a commercial powder by successive (NH4)2SO4 fractionation, acetone precipitation, and ion-exchange chromatography on phosphate- and DEAE-cellulose columns. The purified enzyme was found to be homogeneous by ultracentrifuge-sedimentation analysis (S20, W equal 3.63S), but electrofocusing in polyacrylamide gels and electrophoresis at pH 3.2 revealed that it consists of two very closely migrating bands. No difference in the amino acid composition and enzymic activities of the two partially separated bands could be detected, and it was concluded that the acid proteinase exists in two molecular forms. The enzyme activates bovine trypsinogen and chymotrypsinogen at pH 3.5 (the kappacat. and Km values at 35degrees C are 11.3S- minus 1, 0.10mM and 1.14S- minus 1, 0.18mM respectively). It hydrolyses the Phe-Phe bond of the synthetic pepsin substrates Z-His-Phe-Phe-OEt (kappacat. equal 1.65S- minus 1, Km equal 0.640mM at pH 3.5, 30degrees C) and Z-Ala-Ala-Phe-Phe-OPy4Pr (kappacat. equal 0.37S- minus 1, Km equal 0.037 mM at pH2.9, 39degrees C), where Z represents benzyloxycarbonyl and OPy4Pr represents 3-(4-pyridyl)-propyl 1-ester. Activation of bovine chymotrypsinogen results from the cleavage of the Arg(15)-Ile(16) bond in the zymogen. No other cleavages were observed. The use of A. oryzae proteinase provides a simple tool for the production of pi-chymotrypsin in good yield and purity.

Amino Acids↗