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Biomedical subjects

D Hamilton

Publications and source records attributed to D Hamilton.

At least 55 records · Page 3Linked to original sources
PubMed1978

Some experience with paraplegia in a small hospital in Nepal.

Paraplegia is a common problem in developing countries. They are the most pitiable group of cases seen, but they can all be offered some help, however limited one's resources. The main causes are Potts Disease, arachnoiditis, tropical spastic paraplegia, trauma, lathyrism and cord compression. The usual trauma is falling from trees and the use of trained monkeys to gather leaves and nuts whilst humorous should not be dismissed. The author saw some 35 cases of paraplegia, of which four are described--two good results and two bad. The physician going to a developing country is advised to prepare himself for the care of these cases and to be prepared to motivate staff, patients and relatives. He will find local medical assistants are kind and enthusiastic and rapidly acquire the necessary skills. Nearly all cases should receive a simple and inexpensive anti-tuberculous regime, vitamins and a very generous diet. Necessary equipment required for the home should be locally made and nothing requiring more than simple maintenance should be used.

Adult↗
PubMed1978

Analysis of bacteriophage P1 immunity by using lambda-P1 recombinants constructed in vitro.

We describe the dissection and reconstruction of a complex control circuit, the P1 immunity system, by a method that involves inserting EcoRI-generated fragments of P1 DNA into lambda vectors that can then be sequentially inserted into a bacterial cell. Using these techniques we have isolated lambda-P1 hybrid phages that express the products of P1 genes c1, c4, ant, and ban and, in appropriately constructed lysogens, confirmed the roles played by the first three of these products in phage immunity. In addition we have localized to particular P1 fragments the sites requisite for expression and repression of these gene products. The analysis leads to the conclusion that gpant acts in trans to antagonize repression mediated by gpc1, in support of one of two proposed models for gpant action. Moreover, two features of the immunity system are revealed: (i) a hitherto unknown component that effects gpc1 repression; and (ii) an unexpected ability of gpc4 to channel a superinfecting c1+ phage into the lysogenic state, which suggests that gpc4 activity regulates the establishment phase of lysogeny.

Alleles↗
PubMed1977

Cyclic AMP-dependent protein kinase activation in hearts from euthyroid and hyperthyroid rats.

The degree of cyclic AMP-dependent protein kinase activation in response to dibutyryl cyclic AMP and norepinephrine was determined in samples of rat heart obtained from hyperthyroid and euthyroid animals. The data indicate that thyroid hormone-induced supersensitivity to the metabolic effects of the catecholamines cannot be explained on the basis of a change in activity of supernatant protein kinase.

Animals↗
PubMed1976

Trinucleate pollen in the genus Populus.

It is shown by light microscopy and microspectrophotometry that several Populus species produce trinucleate pollen. Such pollen seems more widespread than previously acknowledged.

Cell Nucleus↗
PubMed1976

The immediate treatment of heatstroke.

The nature, diagnosis and treatment of heatstroke has been discussed. The importance of prevention, recognition and active and early treatment has been emphasised.

Brain Diseases↗
PubMed1976

Transfer of parental immunity to infectious laryngotracheitis in chicks.

The transfer of parental immunity to infectious laryngotracheitis was appraised by measuring serum antibody levels in 150 chicks from the day of hatch up to five weeks. The breeder flock which had received primary vaccination at eight weeks and a booster at 20 weeks transferred high antibody levels which fell markedly within two weeks and remained constant thereafter. Chicks whose parents were vaccinated at 20 weeks only, had low antibody levels throughout. These low levels, in either group of chicks, appeared to offer marginal protection only and were unlikely to inhibit the response to primary vaccination.

Animals↗
PubMed1975

Influence of personality on achievement of medical students.

In this study second year medical students completed a battery of psychometric tests which measured both cognitive and non-cognitive personality traits. Personality profiles obtained have been compared with reported norms from some other published sources. The scores obtained from factor analyses of these tests were used as predictors of total achievement in cellular biology and physiology over two years. In agreement with reports by other authors we found that the most important trait contributing to achievement was introversion/extra-version with introversion correlating with high achievement particularly in multiple choice tests. Emotional maturity was also a major factor especially as a predictor of success in essay tests. General mental ability, verbal skills, and reading comprehension appeared as significant predictors of achievement, and these were apparently of comparable importance in both kinds of test. Students of foreign origin whose first language was other than English tended to perform better in essay than multiple choice tests but their overall performance was lower than would have been expected from their other personality traits including their verbal skills. On the other hand, students resident in college halls tended to have better overall performance than expected.

Achievement↗
PubMed1975

Reasons for differential performance in multiple choice and essay tests.

1. Previous studies with preclinical students demonstrated that there were factors other than topic content which produced significant differences in performance in multiple choice (MC) and essay (E) tests. 2. In this study second year medical students completed a battery of psychometric tests measuring both cognitive and non-cognitive personality traits. 3. The scores obtained after factor analyses of these tests were used as predictors of the difference in performance in 6 matched pairs of MC and E achievement tests over 2 years. 4. Students with high scores in a factor associated with introversion achieved better results in MC tests than would have been expected from their performance in E tests. On the other hand, students whose first language was not English did not perform as well in MC as they did in E tests. 5. Students with high scores in a factor associated with emotional maturity and illegible writing performed better in E tests than would have been expected from their MC results.

Analysis of Variance↗
PubMed1975

The effect of mixed grazing of sheep and cattle on worm burdens in lambs.

Lambs from ewes grazed without cattle at 4.9, 7.4 and 9.9 ewes and lambs per hectare and from ewes run with steers at an equivalent median stocking rate at four ratios in which sheep comprised 30%, 40%, 50% and 70% of the animal equivalents were killed and examined for worms. When sheep grazed alone, there was no significant increase in the number of worm species normally found in sheep, namely Ostertagia circumcincta and Nematodirus spathiger, with an increase in stocking rate. When sheep grazed with cattle, there was a decrease in the number of worm species normally found in sheep but an increase in the number of those normally found in cattle, namely Cooperia oncophora and Trichostrongylus axei, as the proportion of cattle in the ratio increased. The total worm burdens were low due to the management of the flock and parasites were not shown to have affected productivity. The results are discussed and the practical aspects of the findings are presented.

Abomasum↗
PubMedDate not supplied

Experimental laser phototherapy of the Morris 7777 hepatoma in the rat.

The tumoricidal effect of the activation of hematoporphyrin derivative (HpD), by an argon-ion-dye-laser (wavelength 630 nm), was investigated in the Buffalo rat bearing subcutaneous implants of the Morris 7777 hepatoma. Tumor growth was monitored by measuring the tumor volume with constant force calipers. In control animals and those that were pretreated with HpD alone (10 or 20 mg per kg by i.p. injection) or laser light alone (2,000 J at 100 mW), a predictable exponential growth pattern of the cancer was observed. Animals were pretreated with HpD (10 mg per kg by i.p. injection) 48 hr prior to the fiberoptic, intratumor delivery of laser radiation (2,000 J at 100 mW), when the tumor had reached a volume greater than 1.5 cm3. Forty-eight hours after combined laser and HpD treatment, the hepatoma underwent coagulation necrosis, and the tumor volume rapidly increased from a mean value of 1.8 +/- 0.7 cm3 S.D. to a value of 5.8 +/- 1.5 cm3 S.D., compared with a mean of 3.7 +/- 0.7 cm3 S.D. in animals who had not received laser phototherapy. Rats treated with HpD and laser light survived longer (mean survival time 48 +/- 12 days S.D.) than did the other animals treated with the laser alone or HpD alone (mean survival time 31 +/- 16.5 S.D.). Tissue biodistribution studies with tritiated hematoporphyrin derivative, given with doses of 10 and 20 mg per kg of HpD, showed higher concentrations of the dye in the liver, kidneys and spleen than in the tumor at 48 hr after administration of the dye.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗