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Biomedical subjects

P Ravenscroft

Publications and source records attributed to P Ravenscroft.

8 recordsLinked to original sources
PubMed1990

The effects of ingestion time of gliclazide in relationship to meals on plasma glucose, insulin and C-peptide levels.

The effect of altering the timing of gliclazide administration in relation to a meal was studied in ten type 2 (non-insulin dependent) chronically treated diabetics. Gliclazide was given 30 min before, at the start of and 30 min after breakfast or omitted altogether. Plasma gliclazide was present at greater than 2 mg/l throughout the study periods. Administration at 30 min after the meal significantly delayed the time to peak for plasma gliclazide. No significant difference was noted in plasma glucose, insulin or c-peptide patterns with any protocol. It is concluded that, in clinical practice, with chronically treated diabetics the timing of gliclazide ingestion in relation to meals is not critical.

Aged↗
PubMed1990

Cyclosporin-responsive enteropathy and protracted diarrhea.

We describe a child born to unrelated parents who developed severe protracted secretory type diarrhea associated with subtotal villus atrophy and intestinal inflammation at the age of 19 months. No infectious, metabolic, or anatomical basis for this condition was identified and the child required total parenteral nutrition for a period of 18 months despite trials of special enteral formulas, steroids, and anti-inflammatory agents. This refractory "enteropathy" responded dramatically to the introduction of cyclosporin, with cessation of the secretory diarrhea, recovery from the enteropathy, and cessation of parenteral nutrition. The symptoms relapsed when cyclosporin was briefly discontinued and improved following reintroduction of this drug. This experience suggests a role for immune factors in the pathogenesis of the enteropathy in this case and that a trial of cyclosporin is worthy of consideration in similar cases.

Cyclosporins↗
PubMed1986

Synthesis and antiviral properties of 5-(2-substituted vinyl)-6-aza-2'-deoxyuridines.

The following 5-(2-substituted vinyl)-6-aza-2'-deoxyuridines were synthesized: (E)-5-(2-bromovinyl) (2) (6-aza-BVDU), 5-(2-bromo-2-fluorovinyl) (a mixture of E and Z isomers) (3), (E)-5-(2-chlorovinyl) (4), (E)-5-[2-(methylthio)vinyl] (5), 5-(2,2-dibromovinyl) (6), and 5-(3-furyl) (7). The synthesis of 2-6 utilized Wittig-type reactions on 5-formyl-1-(2'-deoxy-3', 5'-di-O-p-toluoyl-beta-D-erythro-pentofuranosyl)-6-azauracil (16). 6-Aza-BVDU (and its alpha-anomer) was also synthesized from (E)-5-(2-bromovinyl)-6-azauracil (12) by using standard deoxyribosidation methodology. Compound 7 was prepared from 5-(3-furyl)-6-azauracil (33) via a ribosidation/deoxygenation sequence. An attempt to prepare the corresponding 5-(2,2-difluorovinyl) analogue afforded instead a mixture of the 5-[(2,2-difluoro-2-methoxy)ethyl] and 5-(2,2,2-trifluoroethyl) derivatives 29 and 30. Compounds 2-7, 29, and 30 were tested for in vitro activity against herpes simplex virus types 1 and 2 (HSV-1, HSV-2). 6-Aza-BVDU (2) exhibited ID50s of 8 micrograms/mL vs. HSV-1 and 190 micrograms/mL vs. HSV-2. BVDU (1) had ID50s of 0.015 and 1.6 micrograms/mL against HSV-1 and HSV-2, respectively. Compound 4 showed a similar profile of activity, but the other analogues were either weakly active or inactive.

Animals↗
PubMed1978

Saliva lithium concentrations in the management of lithium therapy.

To define conditions under which saliva lithium carbonate concentrations can be used as a guide in lithium therapy, serum (Cp) and saliva (Cs) concentrations were determined simultaneously under different circumstances in 12 patients receiving lithium, and the effect of seven variables for example, (sex, saliva flow rate) on the Cp:Cs ratio was examined. The average ratio was 0.57 if saliva was collected in the morning before breakfast and 0.45 otherwise. The Cp:Cs ratio was found to vary much more between individuals than within an individual. We propose a method that minimizes the effect of the interindividual variation on the error in the prediction of Cp from Cs by using one or two measured Cp:Cs ratios to adjust the individual ratio. Using this technique the Cs may be useful as a predictor of the Cp in monitoring lithium therapy.

Aged↗
PubMed1975

Living and working in the United States of America. Some notes for the Australian graduate.

Medical licensing in the United State of America is dependent on examination in addition to education and training. Licenses are granted by each State, and each State has individual requirements. These requirements may include the Educational Council for Foreign Medical Graduates (ECFMG) certification, internship, visa status and the foreign licensing examination(FLEX) certificate. These factors are discussed in some detail. Temporary licensure for the physician who works in a training institution is also discussed. Ecomic pressures may force the physician on an Australian stipend to consider working outside his fellowhip or residency. Licensing for the foreign medical graduate who intends working in the United States is complex, and specific questioning of a potential employer regarding licensing is very important.

Australia↗
PubMedDate not supplied

Intravenous disopyramide in acute myocardial infarction: a haemodynamic and pharmacokinetic study.

We studied the haemodynamic and pharmacokinetic effects of intravenous disopyramide phosphate in 12 patients (average age, 59 years) with proven transmural myocardial infarction, whose symptoms began less than 12 h prior to the study. The aim was to assess the effects of intravenous disopyramide (2 mg/kg given over 5 min) on cardiac index (CI), left ventricular filling pressure (LVFP), heart rate (HR), mean systemic arterial blood pressure (BP), and systemic vascular resistance (SVR) for 60 min after administration of the drug. Both total and free concentrations of disopyramide in the plasma were also measured. A significant elevation (p less than 0.01) of LVFP (estimated indirectly as pulmonary artery end-diastolic pressure) occurred and persisted through the 1-h evaluation period. There was a small but significant (p = 0.02) initial fall in CI and a rise in SVR (p = 0.05). No significant changes occurred in HR or BP. Serum concentrations of disopyramide reached recommended therapeutic concentrations. There was no significant correlation of the changes in cardiac variables from pretreatment values with total serum concentrations, but the free concentration of disopyramide in plasma correlated better with cardiac effect, and the relationships of the free concentration of disopyramide to the changes in LVFP and in SVR from pretreatment values were significant (p less than 0.05). In two patients studied in detail, there was evidence of dose-dependent protein binding of disopyramide.

Aged↗