Biomedical subjects
Publications and source records attributed to M McDonald.
A case of testicular tumor in an intersex patient is presented. Knowledge of the potential of gonadal malignancy is important in the management of disorders of sexual differentiation. These patients, in whom the fields of oncology, embryology, endocrinology, and genetics intersect, provide a fruitful ground for clinical investigation.
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We have investigated the in vivo biosynthesis of the minor hemoglobin components in the rhesus monkey. The elution profile of rhesus hemolysate on BioRex 70 cation exchange resin was analogous to that of human hemolysate. The rhesus Hb Alc peak was identified with the TBA test, which revealed a carbohydrate content identical to that of human Hb A1c. A rhesus monkey was injected with autologous 55Fe-bound transferrin, and the specific activity of each of the minor and major components was followed for over 70 days. As previously shown in man, rhesus Hb alc accumulated specific activity almost linearly over the erythrocyte life-span, indicative of slow and continuous conversion of Hb A0 to Hb Alc. This study revealed two new findings. (1) The specific activity of rhesus Hb Alb was always significantly less than that of Hb Alc. This result suggested that HB Alb is made by further posttranslational modification of Hb Alc. (2) The first portion of rhesus Hb A0 to be eluted on BioRex 70 contained a significant amount of carbohydrate and lower initial specific radioactivity than did the latter portion. This unexpected heterogeneity in the major hemoglobin component reflects slow, nonenzymatic glycosylation at sites other than at the N-terminus of the beta-chain.
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A pilot study of cancerous diseases of the large bowel in Canterbury is described. The experience of 346 patients derived from the Cancer Registry for 1970-72 is presented. The feasibility of the method is demonstrated with the identification of guidelines for future work. The preliminary results suggest some special features in New Zealand. While demographic characteristics do not appear to help in defining persons at high risk from cancerous diseases of the large bowel, nevertheless other features of the natural history of this disorder indicate that it might be feasible to define high risk profiles.
Vitreous haemorrhages were induced in rabbits and the echographic appearances of A and B scan were correlated with the gross and histologic appearances over a period of twenty weeks. In all cases, visible vitreous opacities produced distinct echo patterns. As the haemorrhages cleared, the echo amplitudes became progressively weaker. Several patterns of vitreous "membranes" on B scan were also observed. Pathological examination revealed that such membranes were composed of red cells, macrophages and condensed vitreous collagen. It is suggested that haematogenous vitreous membranes of this type are readily diagnosed by combined A- and B-scan ultrasonic examination, and are probably amenable to surgery.
A comparison made between five techniques for introducing additional gas to the stomach for double contrast barium examination showed effervescent tablets to be associated with significant improvement in gastric mucosal coating with significantly less bubble formation. A proprietary effervescent health salt on the other hand was associated with significantly greater bubble formation.
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The effects of several variables on compositional response rate were investigated in three classrooms. After establishing baseline composition rates in each of the three classrooms, an experimental phase was introduced that consisted of: explicit timing of the children's composition period with a stopwatch, immediate feedback on the number of words each child produced, public posting of the greatest number of words written by each child to date, and instructions to try to exceed their highest score. In the second-grade classroom, these conditions were introduced, removed, and re-introduced. In two fifth-grade classrooms, these conditions were introduced according to a multiple baseline, across classes. In all cases, introduction of the experimental conditions led to a doubling of rate of words written by students and an increase in subjective quality ratings of compositions made by independent judges.
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