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Biomedical subjects

R F Lowe

Publications and source records attributed to R F Lowe.

At least 19 recordsLinked to original sources
PubMed1992

Failure of interleukin-2 to alter systolic blood pressure in Dahl salt-sensitive rats.

The effect of interleukin-2 (IL-2) on systolic blood pressure in Dahl salt-sensitive rats was investigated. The treatment group received human IL-2 injections (5000 units/kg). Control animals received subcutaneous saline injections. Both groups of animals were placed on a diet containing 1.5% sodium the day of the first injection and maintained on that diet for the duration of the study. Systolic blood pressure increased in both the IL-2 treated and the control groups (P = .0001) over 7 weeks. The increase in SBP was the same for both groups (P = .8823 for between group differences). At the end of 7 weeks, when SBP in both groups was elevated to a similar degree, the IL-2 group and the control group were each administered 5000 units/kg of IL-2. SBP in both groups remained elevated, showing no decrease over the next two weeks. These results indicate that perhaps unlike in SHR, IL-2 does not alter systolic blood pressure in Dahl salt-sensitive rats.

Animals↗
PubMed1989

Interactions between circulating peptides and the central nervous system in hemodynamic regulation.

Enkephalins and endothelins are endogenous peptides, which, at least at pharmacologic doses, produce complex hemodynamic responses after intravenous administration. The enkephalins, when injected into conscious animal models and humans, increase blood pressure, heart rate and minute ventilation. This response occurs by activation of specific opiate receptors located outside the bloodbrain barrier; the actual mechanism involves an increase in adrenergic autonomic nervous system tone and a decrease in cholinergic tone. These opiate receptors may activate afferent fibers, perhaps nicotinic cholinoceptors; in many ways their properties are suggestive of chemoreceptors. Furthermore, enkephalin responses appear to be modulated by gamma-aminobutyric acid complexes, in that the reversal of the excitatory hemodynamic responses seen in the conscious state to vasodepressor responses after barbiturate anesthesia may result from alteration of the state of activation of the gamma-aminobutyric acid complex. The enkephalin receptors are localized to the vertebral artery vascular distribution; the specific site may be the area postrema, a blood-brain barrier-deficient circum-ventricular organ demonstrated to modulate heart rate and blood pressure and to represent a target site for circulating angiotensin II. Endothelin increases heart rate and blood pressure when infused slowly into conscious or anesthetized dogs, although barbiturates do blunt the increase in heart rate. The mechanism appears to involve modification of autonomic tone, but also some element of direct vasoconstrictor activity. Interestingly, rapid bolus doses of endothelin produce only vasodepressor responses, suggesting that the rate and concentration at which circulating endothelin reaches afferent receptors or vasoconstrictor sites on vascular smooth muscle may determine the net hemodynamic response observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

The effect of area postrema lesions on hemodynamic responses to systemic methionine-enkephalin in conscious dogs.

In the intact conscious dog, intravenous methionine-enkephalin (ME) increases heart rate and mean arterial blood pressure (MAP). These hemodynamic responses are produced at lower dosages when ME is injected into the vertebral artery, but not the carotid artery, suggesting that ME receptors are localized in the vertebrobasilar artery circulation. The area postrema (AP), a circumventricular organ devoid of a functional blood-brain barrier, represents a likely site for these receptors. We have tested the effects of chronic AP ablation upon hemodynamic responses to ME in conscious dogs. In three dogs with subtotal AP destruction, ME responses were preserved. However, in another dog with complete ablation of both the AP and the area subpostrema, ME responses were eliminated. These results indicate that total destruction of the AP, and perhaps of deeper structures as well, is necessary to abolish hemodynamic responses to ME.

Animals↗
PubMed1988

Clinical types of primary angle closure glaucoma.

There is no internationally adopted terminology for the clinical types of primary angle-closure glaucoma. Descriptions of three clinical types: 1. intermittent angle closure; 2. acute and subacute angle closure; and 3. creeping angle closure are presented with reasons for the division into and naming of these types. Chronic angle closure is not a distinct form but a late derivation from various types of angle closure.

Acute Disease↗
PubMed1988

N-allylnormetazocine: hemodynamic actions and inhibition of leucine-enkephalin hemodynamic activity in conscious dogs.

The hemodynamic actions of dl-, d-, and l-N-allylnormetazocine (NANM) were examined. dl-NANM significantly increased heart rate and systemic arterial pressure in a dose-dependent manner. Naloxone (1 mg/kg) inhibited the hemodynamic actions of 0.5 mg/kg dl-NANM. At a dose of 0.25 mg/kg, l-NANM, but not d-NANM, significantly increased heart rate and mean arterial pressure. The effects of l-NANM were blocked by naloxone but not by naloxone-methylbromide, indicating that the opiate effects are mediated by receptors located in the central nervous system. At a higher dose (0.5 mg/kg), d-NANM consistently produced small increases in heart rate and blood pressure which were statistically significant. The hemodynamic actions of Leu-enkephalin were inhibited by pretreatment with dl-NANM and l-NANM but not d-NANM. These results indicate that NANM has opiate hemodynamic activity which resides with the levorotary isomer. Dextrorotary isomer activity is nonopiate or possibly nonspecific. Furthermore, there appears to be a inhibitory interaction between NANM-opiate and enkephalin hemodynamic actions. This suggests that NANM-opiate receptors may be involved in modulation of the hemodynamic response to circulating enkephalins.

Animals↗
PubMed1987

Persistent symptoms after peripheral iridectomy for angle-closure glaucoma.

Symptoms that persist after operations for angle-closure glaucoma arise from different causes. In the presence of open peripheral iridectomies miotics may be beneficial or may close angles; wide pupil dilatation by phenylephrine used to diminish posterior synechiae may close angles; cycloplegic mydriatics will close some angles and open others. Unexpected bizarre reactions to eye drops may occur. Persistent chronic glaucoma will be more common after laser iridotomy than after correctly assessed filtering operations. The importance of gonioscopy in diagnosis and management is emphasised.

Acute Disease↗
PubMed1986

Availability of lysine in meat meal, meat and bone meal and blood meal as determined by the slope-ratio assay with growing pigs, rats and chicks and by chemical techniques.

1. The availability of lysine in four meat meals (MMs), four meat and bone meals (MBMs) and two blood meals was determined using the slope-ratio assay with growing pigs, rats and chicks and with two chemical techniques. 2. The availability of lysine (proportion of total) in the eight MMs or MBMs ranged from 0.48 to 0.88 for pigs, from 0.49 to 0.88 for rats and from 0.68 to 0.88 for chicks. There was no apparent relation between the availability estimates for pigs, rats and chicks for the individual meals. 3. For the two blood meals, availability estimates were 1.03 and 1.13 for pigs, 0.81 and 0.80 for rats and 1.07 and 1.02 for chicks. 4. Values for the indirect and direct 1-fluoro-2,4-dinitrobenzene-'available'-lysine assays ranged from 0.77 to 0.88 and 0.78 to 0.93 respectively for the eight MMs and MBMs. There appeared to be no relation between these values and the pig estimates.

Animal Feed↗
PubMed1986

Nutritional value of lupin (Lupinus albus)-seed meal for growing pigs: availability of lysine, effect of autoclaving and net energy content.

1. Two experiments were conducted to assess the nutritional value of lupin (Lupinus albus)-seed meal for growing pigs. In the first, the availability of lysine was assessed using slope-ratio analysis. In the second, the effects of autoclaving lupin seeds and formulating the diets on the basis of estimated digestible or net energy were assessed. 2. In the first experiment, the availability of lysine in three samples of lupin-seed meal was compared with that in meat-and-bone meal and soya-bean meal. Availability of lysine in the five protein concentrates, using food conversion efficiency on a carcass basis as the criterion of response, was (proportion of total): lupin-seed meal no. 1 0.44, no. 2 0.57, no. 3 0.53, meat-and-bone meal 0.42, soya-bean meal 0.80. 3. Availability estimates, based on protein deposited:food intake, were: lupin-seed meal no. 1 0.82, no. 2 0.73, no. 3 0.70, meat-and-bone meal 0.27, soya-bean meal 0.77. These estimates had higher standard deviations than those based on carcass response. 4. Regressing the measures of response v. lysine intake resulted in estimates of availability similar to, or higher than, the slope-ratio analysis but was associated with greater statistical invalidity and higher standard deviations. 5. The proportion of energy retained in the carcasses was unaffected by the inclusion levels of lysine or soya-bean meal. Energy retention was depressed (P less than 0.05) with the three lupin-seed meals and the meat-and-bone meal. 6. In the second experiment, the response of pigs given a diet containing lupin-seed meal was inferior, on a carcass basis (P less than 0.05), to that of pigs given a diet containing soya-bean meal formulated to similar total lysine and digestible energy contents. 7. The addition of soya-bean oil to the diet containing lupin-seed meal, to equalize the estimated net energy of the diet to that of the diet containing soya-bean meal, depressed protein deposition (P less than 0.05) and increased fat deposition (P less than 0.05), indicating that energy was not limiting the growth of pigs given the lupin-seed-meal diet. 8. Autoclaving the lupin-seed at 121 degrees for 5 min had no effect on the growth of pigs, indicating that the low availability of lysine was not due to the presence of heat-labile anti-nutritional factors.

Animal Feed↗
PubMed1985

Andrew Sexton Gray (1826-1907). A founder of Australian ophthalmology: his life and times.

Andrew Sexton Gray was born in Limerick, Ireland, medically trained in Dublin, and was assistant to William Wilde, the distinguished oculist and aurist. He migrated to Victoria in 1859, was surgeon to a railway's construction company, then in 1862 began practice as a surgeon and oculist in Melbourne. In 1863 he founded a charitable eye and ear hospital, and had a very active, long life devoted mostly to ophthalmology. The hospital progressively expanded and became the centre for training for many ophthalmologists, as well as the nucleus for the cohesion of Victorian ophthalmology. History shows Andrew Sexton Gray to have been a founder of Australian ophthalmology.

Australia↗
PubMed1984

An outline history of ophthalmology in Australia.

The first ophthalmologists came to Australia from Great Britain in the early 1860s and founded charitable eye hospitals on the British pattern. For many years, during which Australian States remained colonies of Great Britain, all specialist medical training was obtained overseas. World War II greatly accelerated Australian independence and stimulated Australian technology, science, education, culture and economics. Australian ophthalmologists met the challenge with tight organization, home-based training, academic responsibilities and research.

Academies and Institutes↗
PubMed1983

T. Aubrey Bowen, oculist, 1837-93. His charitable bequests in Victoria.

During the economic depression which engulfed Victoria in the 1890s, T. Aubrey Bowen bequeathed 20,000 pounds for division amongst Victorian charitable and benevolent institutions. Five buildings resulting from this bequest were: the Aubrey Bowen Wing at The Victorian Eye and Ear Hospital, the Bowen Memorial Operating Theatre at the Melbourne Hospital, the Bowen Block at the Austin Hospital, the Aubrey Bowen Operating Room and Wards at the Geelong Infirmary and Benevolent Asylum, and the Aubrey Bowen Cottage at the Old Colonists' Homes.

Australia↗
PubMed1978

The sero-anthropology of the Rhodesian Lemba.

122 Rhodesian Lemba were blood grouped to establish whether there was any serological evidence to support their claim to be immigrants into central and southern Africa; and whether their endogamous practices had resulted in blood group frequencies different from those of their present neighbours. Our results are typical of those found in central Africa, and show no similarity to the blood group frequencies of populations outside sub-Saharan Africa.

Anthropology↗
PubMed1976

Serum cholinesterase variants in African leprosy patients resident in Rhodesia.

Blood samples from 580 African leprosy patients living in Rhodesia have been phenotyped for the plasma cholinesterase variants. The Africans have been grouped according to country of origin and tribal affiliation. We have found no individual with an Ea1 gene and are unable to resolve the contradictory evidence for an association between this gene and leprosy. The frequency of the Ef1 gene is higher than that usually found in Caucasian populations, being 0.046 in lepromatous leprosy patients and similar to the 0.056 found in healthy African controls. In tuberculoid leprosy patients the frequency is, however, significantly lower at 0.019. On the other hand, the frequency of the C5+ variant is essentially the same for the tuberculoid leprosy patients and the healthy controls (4%) while for the lepromatous leprosy patients it is about 7% approaching the 10-15% found in many Caucasian populations.

Cholinesterases↗