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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
PubMed2000

Comparison of oil recovered from tea tree leaf by ethanol extraction and steam distillation.

Two methods for the determination of oil and oil major components from tea tree (Melaleuca alternifolia) leaf are quantitatively compared. A microwave assisted ethanol extraction and a 2-h hydrodistillation technique were used on both dry and fresh leaf from a low and a high oil concentration tree. There was no significant difference between dry and fresh leaf. The distillation technique recovered 88% and 82% of the extractable oil for the low and high concentration material, respectively. For both samples this distilled oil was composed of lower absolute amounts of sesquiterpenoids and marginally lower amounts of monoterpenoids. Extending the distillation to 6 h increased the sesquiterpenoid recovery but this resulted in a reduction in both the absolute and relative amounts of the oxygenated monoterpenoids, terpinen-4-ol and 1,8-cineole.

Chromatography, Gas↗
PubMed1997

Georg Bartisch: Ophthalmodouleia, der Augendienst, 1583. A treatise on service of the eyes and a review of the chapter on strabismus.

In 1583, Georg Bartisch, oculist and cutter for bladder stones at the court of Duke August I of Saxony, published at his own expense a 273 page textbook of ophthalmology. It contained 91 wood cuts and, in the present volume, they are presented in brilliant colour as they were in the original books prepared for presentation. The book was one of the first medical treatises to be published in the German vernacular instead of traditional Latin. It has been translated into English and published in gothic type to simulate the original. Treatment of diseases of the eye by medicines or surgery are reported in great detail. It gives an account of ophthalmology at the time of the early Renaissance when enlightenment was beginning to overtake the darkness of the Middle Ages.

Germany↗
PubMed1997

John Wilkins MRCS, FRCS (Edin.), 1826-1905: his house at 121 Collins Street East, Melbourne.

The three-storeyed house at 70 Collins Street (formerly 121 Collins Street East), Melbourne, was built in 1857 as a home and surgery for Dr John Wilkins. It was associated for 100 years with surgical practice, especially general surgery and eye and ENT diseases, then with obstetrics and gynaecology, but in time had to yield to commercial pressures. However, the exterior remains intact, its special architecture reminiscent of its early elegance.

Architecture↗
PubMed1996

John Wilkins, surgeon, 1826-1905: experiences in Williamstown (Melbourne) and New Zealand.

John Wilkins was a prominent colonial surgeon for 15 years in Williamstown, Victoria. During the early gold rushes he prospered from investments in property. In Melbourne he aimed to become a recognized authority in diseases of the eye and throat, but he did not achieve his aims, and caused bitterness in the medical community by advertising. After 10 years he moved to Dunedin where he produced the first publication on anaesthesia in New Zealand. He moved to Christchurch, but found contentment in Auckland where he practised general medicine with special consultations in general surgery and diseases of the eye, ear, nose and throat, and where he lived for the remainder of his life.

Advertising↗
PubMed1995

Acute glaucoma--1941.

PURPOSE: To describe the treatment of acute glaucoma before the technological and pharmacological advances that followed World War 2. METHOD: A narrative of personal experience is presented. CONCLUSIONS: In 1941, acute congestive glaucoma received heroic treatment - strong miotics, blood-letting by leeches, purging with mercury. If satisfactory response did not occur within four hours, a broad iridectomy was performed on the hard, congested eye. Affected eyes commonly remained blind or with severely reduced vision.

Acute Disease↗
PubMed1994

Preservation of left ventricular function and coronary flow by angiotensin I-converting enzyme inhibition in the hypertensive-diabetic Dahl rat.

The effect of the angiotensin I-converting enzyme (ACE) inhibitor benazepril (55 mg/kg orally) on the preservation of cardiac performance in diabetic-hypertensive Dahl S rats was investigated. Diabetes mellitus was produced by streptozotocin. Fasting (4-h) blood glucose levels were 279 +/- 50 mg/dL in diabetic Dahl salt-sensitive v 79 +/- 5 mg/dL in nondiabetic Dahl salt-sensitive rats. Cardiac performance was determined at the end of 8 weeks in an isolated perfused working heart apparatus. Peak left ventricular pressure (LVPmax), left ventricular peak negative dP/dt, and coronary flow were depressed in diabetic Dahl S rats (P < or = .05 v control). These deficits in cardiac function were not observed in diabetic Dahl S rats chronically treated with benazepril. The beneficial effects of benazepril apparently were independent of systolic blood pressure reduction. Although plasma ACE activity was increased in diabetic Dahl S rats, plasma renin activity was reduced. This suggests that the beneficial effects of ACE inhibition may be due to an effect upon the kinin system rather than the renin-angiotensin system. The benazepril-associated preservation of cardiac function in this study suggests that ACE inhibitors may be beneficial in the treatment of diabetic heart disease.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1994

Edward J Curran and pupillary obstruction.

PURPOSE: To present the importance of the concepts of Edward J Curran in relation to primary angle-closure glaucoma, and include a biographical sketch. METHOD: An historical method is adopted. RESULTS: Curran's propositions of pupillary obstruction and its relief by peripheral iridotomy were conceded only after 30 years, and had to await laser surgery for fulfillment. CONCLUSIONS: Edward J Curran's name should be enshrined in the history of ophthalmology.

Australia↗
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↗