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Biomedical subjects

G W Harris

Publications and source records attributed to G W Harris.

At least 37 records · Page 2Linked to original sources
PubMed1983

A comparison of the effects of phacoemulsification and nucleus expression on endothelial cell density.

A series of patients undergoing extracapsular cataract extraction by phacoemulsification (1,126) or nucleus expression (632) were studied to evaluate the relative effects of emulsification time, irrigating volume, and surgical technique on endothelial cell density. The collective data revealed a higher cell loss with phacoemulsification (15%) than with nucleus expression (12%). Patients over 69.5 years appeared to be more vulnerable to the effects of phacoemulsification than those below 69.5 years. Although the data were subjected to combinations and permutations of age, sex, time, and volume, no direct correlation between emulsification time and/or irrigating volume and endothelial cell loss was shown. When data sets for individual surgeons were analyzed, the most striking difference was between the endothelial effect of anterior chamber phacoemulsification (26% average reduction) and that of posterior chamber phacoemulsification (13% average reduction).

Age Factors↗
PubMed1983

Trace nitrogenous species in urban atmospheres.

Recent results concerning the identification and measurement of nitrogenous air pollutants in the California South Coast Air Basin (CSCAB) are presented. In planning or evaluating studies of the human health effects of these pollutants, it is important to consider the entire range of species which may be present. We provide estimates of typical exposures to nitrogenous air pollutants during a single day oxidant event in the CSCAB.

Air Pollutants↗
PubMed1982

Evaluation of a diabetes education programme.

An education programme was evaluated for 140 insulin-dependent diabetics and their family members from 1978 to 1980. Dietary, biochemical and other assessments were made before and 6 months after the programme. As a group, the diabetics were initially in good metabolic control and this was maintained, or improved, over the study period. The programme recommended a diet in which complex carbohydrate constituted at least 45% of energy intake and fat was limited to 30%. The diabetics and their family members significantly increased their consumption of complex carbohydrate and decreased fat intake. On this regimen, diabetics did not gain weight and their relatives lost weight. There were also improvements in knowledge of the disorder and in perceptions of susceptibility to complications and barriers to compliance.

Attitude to Health↗
PubMed1970

The luteinizing hormone releasing activity of extracts of blood from the hypophysial portal vessels of rats.

1. A method of acid ethanol extraction and gel filtration was used to obtain a ;luteinizing hormone (LH)-free' fraction of blood collected from the cut pituitary stalk of rats (termed hypophysial portal blood).2. The ;LH-free' fraction of hypophysial portal plasma from hypophysectomized and from ovariectomized rats caused a greater depletion of ovarian ascorbic acid in immature rats, pretreated with gonadotrophins, than a similar fraction of systemic plasma obtained from the same donor animals.3. The ;LH-free' fraction of hypophysial portal plasma from ovariectomized rats evoked a rise in the level of LH in the systemic plasma of ovariectomized, oestrogen and progesterone treated, rats. This fraction also caused ovulation in rabbits when infused directly into the anterior pituitary gland of these animals. The activity of the ;LH-free' fraction of systemic plasma was considerably less than that of portal plasma in either of these assay systems.4. The results of these experiments suggest the presence of a factor in the ;LH-free' fraction of hypophysial portal plasma which is capable of causing the release of luteinizing hormone from the anterior pituitary gland. The molecular weight of this factor, as assessed by its behaviour on filtration through ;Sephadex G-25', is probably less than 5000.5. The LRF activity of the ;LH-free' fraction of hypophysial portal plasma obtained from rats at various phases of the oestrous cycle was measured by the ovarian ascorbic acid depletion method. There appears to be a decrease in the level of activity at oestrus. However, a rise in LRF activity, which was expected to occur at the ;critical period' of prooestrus, was not evident. The significance of these findings is discussed.

Animals↗
PubMed1970

Luteinizing hormone releasing factor in rat hypophysial portal blood collected during electrical stimulation of the hypothalamus.

1. Ovulation was induced in Nembutal-blocked pro-oestrous rats by electrical stimulation of the hypothalamus.2. The same type of electrical stimulation was applied during the collection of hypophysial portal blood.3. Pooled hypophysial portal plasma from donors in pro-oestrus, oestrus and met-oestrus was assayed for ovarian ascorbic acid depleting (OAAD) activity.4. Electrical stimulation of the hypothalamus increased the OAAD activity, believed to be due to luteinizing hormone releasing factor (LRF), in pro-oestrus and met-oestrus, but not in oestrus.5. It is concluded that the hypothalamic nerve fibres responsible for releasing LRF into the hypophysial portal vessels are depleted of their store of this releasing factor, or are refractory to electrical stimulation, during oestrus.

Animals↗