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Biomedical subjects

J G Allen

Publications and source records attributed to J G Allen.

At least 55 records · Page 3Linked to original sources
PubMed1993

Plasma and tissue concentrations of alpha-tocopherol during vitamin E depletion in sheep.

To determine the relationship between plasma and tissue alpha-tocopherol concentrations during vitamin E depletion, weaned lambs were placed on a vitamin E-deficient diet for 0, 1, 2, 4, 8 and 12 weeks. alpha-Tocopherol was measured in plasma, erythrocytes, liver, adrenal, adipose tissue, three different skeletal muscles and heart muscle. The alpha-tocopherol concentration in plasma fell at the same rate as the alpha-tocopherol concentration in skeletal muscles, heart muscle, adrenal and adipose tissue. The alpha-tocopherol concentration in liver and erythrocytes fell at a faster rate than that of plasma and all muscle tissues. There were significant correlations between alpha-tocopherol concentration in plasma and alpha-tocopherol concentrations in all the tissues measured. Different skeletal muscles had significantly different concentrations of alpha-tocopherol which may relate to their differing susceptibility to nutritional myopathy. The increase in malondialdehyde in oxidatively-stressed muscle tissue and the correlation with alpha-tocopherol concentration in most muscle tissues indicated that the muscles had reduced antioxidant capacity in vitro as a result of vitamin E depletion. It was concluded that during vitamin E depletion in sheep alpha-tocopherol concentration in plasma was a good index of vitamin E status under the experimental conditions employed.

Adipose Tissue↗
PubMed1993

The clinical biochemistry of experimentally produced lupinosis in the sheep.

Lupinosis was produced in sheep in four experiments by administering a toxic extract of Phomopsis leptostromiformis by various routes and at various dose rates. The course of the intoxication was followed by plasma biochemical analyses for a number of electrolytes, metabolites and enzymes. Results from these analyses suggested that in addition to being an hepatotoxicity, lupinosis also resulted in injury to muscle, kidney and adrenal cortex. This was confirmed by microscopic examination of these tissues.

Administration, Oral↗
PubMed1993

Dissociative processes: theoretical underpinnings of a working model for clinician and patient.

Dissociative symptoms are now widely recognized, but they are nevertheless challenging for clinicians and bewildering to patients. The author presents a conceptual framework for understanding dissociative processes, emphasizing discontinuity in experience and delineating various junctures in the unfolding of dissociative episodes. The conceptual framework provides the theoretical underpinnings for a simple schema that can be used to explain dissociation to patients and to help them articulate their dissociative experience.

Consciousness↗
PubMed1993

Diagnosing dissociative disorders.

The increasing prevalence of dissociative disorders has spawned a range of diagnostic tools. The authors describe the use of several current methods--screening instruments, structured interviews, psychological testing, and hypnosis--and they advocate enlisting the patient as an active collaborator in the diagnostic process.

Amnesia↗
PubMed1992

Optimal length of stay in child and adolescent psychiatric hospitalization: a study of clinical opinion.

Factors contributing to clinical recommendations for length of hospitalization for children and adolescents were investigated. Diagnosis, chronicity, severity of symptoms, response to prior treatment, and family resources were found to relate strongly to length-of-stay recommendations. Guidelines representing the consensus of experienced clinicians are proposed.

Adaptation, Psychological↗
PubMed1992

A lupinosis-associated myopathy in sheep and the effectiveness of treatments to prevent it.

A lupinosis-associated myopathy occurred in 26 of 48 sheep given a crude toxic extract of Phomopsis leptostromiformis, and in 18 of 34 sheep that grazed a toxic lupin stubble. Treatment with selenium or alpha-tocopherol alone neither prevented nor cured the myopathy, but selenium and alpha-tocopherol together may have been partially effective. Among the group of 48 intoxicated sheep, those with myopathy had a significantly lower mean terminal concentration of alpha-tocopherol in their livers than those with no myopathy. There was no relationship between the severity of liver injury and the occurrence of the myopathy. It was considered that this lupinosis-associated myopathy may have a similar pathogenesis to nutritional myopathy. Data on plasma creatine phosphokinase and erythrocyte glutathione peroxidase activities, plasma alpha-tocopherol concentrations and terminal tissue concentrations of selenium and alpha-tocopherol are presented.

Animals↗
PubMed1992

Pharmacokinetics of ticlopidine during chronic oral administration to healthy volunteers and its effects on antipyrine pharmacokinetics.

1. The pharmacokinetics of ticlopidine, a novel antithrombotic agent, have been investigated in 10 healthy volunteers dosed orally with the drug (250 mg 12 hourly for 21 days), to determine the basic pharmacokinetic parameters in humans, to investigate its accumulation during repeated administration, and to assess its effects on hepatic drug-metabolizing enzymes. 2. After the first dose, peak plasma concentrations (median 0.31, range 0.08-0.80 mg/l) were generally found at 2 h. The levels decreased rapidly to a median concentration of 0.087 mg/l by 4 h then declined to 0.022 (range less than 0.005-0.128) mg/l at 12 h after administration, with apparent half-lives of approx. 4 h. The median AUC value for this first dosage interval (AUC tau) was 0.97 (range 0.41-3.49) mg h l-1. 3. Pre-dose plasma concentrations indicated that steady state was reached after 5-10 days, and then remained essentially unchanged through to the end of the study. From 30 h after the final dose, drug levels declined exponentially with a median half-life of 28.8 (range less than or equal to 20-50) h. 4. Following the final dose, the median peak concentration and AUC tau were 0.99 (range 0.22-2.12) mg/l and 4.06 (range 0.90-15.2) mg h l-1 respectively. Based on AUC values, the mean accumulation factor +/- SD was 3.73 +/- 1.14. 5. The metabolic status of subjects was assessed by administration of single doses of antipyrine (700 mg orally) 7 days before the first dose of ticlopidine and 2 days after the final dose. Treatment with ticlopidine decreased antipyrine clearance, demonstrating that it inhibited drug-metabolizing enzymes. Significant correlations (r2 = 0.84, p less than 0.01) were found between the AUC values for ticlopidine and antipyrine, indicating that the interindividual variation in the pharmacokinetics of ticlopidine are explained by differences in metabolic clearance.

Administration, Oral↗
PubMed1992

A psychodynamic approach to the master treatment plan.

Formulating master treatment plans for the hospital treatment of psychiatric patients is especially challenging to psychodynamically oriented clinicians unaccustomed to reducing complex intrapsychic and interpersonal phenomena to specific observable behaviors. In collaboration with a wide cross section of hospital staff members, the authors developed a conceptual framework for treatment plans compatible with psychodynamic thinking. They describe the treatment evaluation research from which the format of the treatment plan evolved, as well as the guide they developed to facilitate its implementation .

Activities of Daily Living↗
PubMed1991

[Local estrogen premedication reduces the abortion time in prostaglandin E1 analogue-induced abortion in the 2nd trimester].

Twenty-eight patients (median gestational age 17 weeks) referred for induction of second trimester abortion, were randomized to intracervical preliminary treatment by either 50 mg 17 beta-oestradiol or placebo. Abortion was then induced by 1 mg prostaglandin E1 vagitories. The preliminary treatment caused a significant rise in cervical score and a significant reduction in induction-abortion time especially by reducing the number of patients with prolonged induction-abortion time.

Abortion, Induced↗
PubMed1990

The Brain laryngeal mask. An alternative to difficult intubation.

We report the case of a young man undergoing fixation of bilateral mandibular fractures, where the anaesthetist was unable to intubate. A Brain laryngeal mask was employed, thus enabling surgery to proceed. This relatively new device enabled the airway to be safeguarded whilst preserving reasonable surgical access for the attachment of Erich arch bars and a four hole osteosynthetic bone plate. The surgical and anaesthetic procedures are summarised. The laryngeal mask is described and its performance and limitations are discussed. We believe this to be the first report of mandibular fracture fixation performed with a Brain laryngeal mask in situ.

Adult↗
PubMed1989

Evidence that phomopsins A and B are not the only toxic metabolites produced by Phomopsis leptostromiformis.

The toxicities of up to four different toxic preparations containing metabolites of Phomopsis leptostromiformis were examined in two experiments with sheep and one with rats. It was shown that the different toxic preparations containing similar amounts of phomopsin A varied substantially in toxicity. Crystalline phomopsin A was the least toxic. It is suggested that the increased toxicity of the other three preparations was due to the presence of toxic metabolites additional to phomopsins A and B. Evidence to support this suggestion is presented.

Animals↗