Biomedical subjects
Publications and source records attributed to G Ward.
The guinea pig is a useful model for otologic research. Common problems encountered in working with individual animals include preexisting chronic middle ear disease, anesthetic deaths, and a lack of knowledge of the surgical anatomy and landmarks of the middle and inner ear. The methods detailed in this article will benefit those interested in a reliable, inexpensive, otosurgical animal model.
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Nineteen sightless children and adolescents aged between 11 and 18 years were tested for physical condition and performance. Their residential school provided four adapted physical education lessons a week, lasting for 45 minutes. Their physical condition and performance was found to be comparable with that of normal sighted children. A supplementary training programme consisting of three extra 60-minute sessions a week for four months to test whether their fitness could be developed further produced only minor changes. It is concluded that a well-designed, adapted physical education programme, in four sessions per week, is sufficient to ensure a normal level of physical condition for sightless children.
A 21-yr-old moderately obese woman with hirsutism, acanthosis nigricans, and oligomenorrhoea was diagnosed as having polycystic ovary syndrome. Despite hyperinsulinemia, binding of insulin to her red cells was within the range for normal, young adult subjects. Her serum did not bind or degrade [125I]insulin or alter its binding to fat cells, and was negative for insulin receptor antibodies. However, her serum caused a dose-dependent inhibition of insulin-stimulated lipogenesis (conversion of [3-3H]glucose to [3H]lipid) in rat fat cells significantly greater than that produced with control serum (relative potency, 3.5:1) and (at a 1:20 dilution) markedly impaired the response of both lipogenesis and 2-deoxy-D-glucose uptake to maximum concentrations of insulin. After the patient was treated with clomiphene for 4 months, her menses resumed, hair growth slowed, fasting blood glucose and plasma insulin concentrations decreased, and serum inhibitory activity decreased to the control range. Serum inhibitory activity was stable to freezing and thawing and to heating at 56 C for 30 min, and could be extracted into acid-ethanol. By dialysis, its mol wt was below 1000, whereas by ultracentrifugation, it was above 3500; both high and low mol wt forms were detected after Sephadex G-50 gel chromatography of serum, suggesting that the inhibitor was of low mol wt but loosely bound to a higher mol wt component in serum. These findings indicate that insulin resistance in this patient with acanthosis nigricans and polycystic ovaries could be attributed to a circulating low mol wt inhibitor of postbinding insulin action.
Six obese, non-insulin-dependent diabetic subjects were studied before and 3 mo after treatment with the sulfonylurea gliclazide, 40-80 mg b.i.d. Fasting plasma glucose fell significantly from 13.4 +/- 1.6 (SEM) to 8.6 +/- 1.2 mmol/L, accompanied by a significant reduction from 40.6 +/- 3.7 to 29.8 +/- 2.8 mM X h of the plasma glucose response to 75 g oral glucose. Fasting plasma insulin showed a nonsignificant increase from 24.8 +/- 2.0 to 31.3 +/- 2.3 mU/L. The percent specific binding of tracer 125I-insulin to erythrocytes and monocytes did not change significantly (from 9.8 +/- 1.7 to 8.5 +/- 0.7 for erythrocytes and 1.7 +/- 0.3 to 1.6 +/- 0.4 for monocytes). Glucose utilization was measured at three levels of insulin infusion (40, 100, and 300 mU/kg/h) by the euglycemic clamp technique. Overall there was a significant (P less than 0.05) increase in the disappearance rate (Rd) and metabolic clearance rate (MCRg) for glucose at the two higher insulin infusion rates (MCRg: 3.3 +/- 0.7 to 5.1 +/- 0.7 and 5.9 +/- 0.9 to 7.9 +/- 0.9 ml/kg/min), but not at the lowest infusion rate (MCRg: 3.6 +/- 0.8 to 3.3 +/- 0.6). Thus, the chronic hypoglycemic effect of gliclazide in obese diabetic subjects was associated with an improvement in insulin-mediated glucose utilization at high plasma insulin concentrations. This enhanced effect of insulin after gliclazide treatment was not accompanied by increased monocyte or erythrocyte insulin binding, which suggests that it was due to potentiation of postbinding insulin-sensitive pathways.
Brief deprivation of vision after unilateral lesions of the frontal eye field prevents the appearance of contralateral inattention to visual, auditory, and somatosensory stimuli. The forced circling that accompanies inattention, however, is not affected. An equivalent preoperative period in the dark only partly reduces inattention symptoms. Visual deprivation does not reduce or prevent inattention resulting from lesions of the superior colliculus.
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The continuous controversy concerning the treatment for acute hydrocarbon ingestions led to a study of the pulmonary effects of kerosene absorption from the gastrointestinal tract in dogs. Gastrostomies and cervical esophageal transections with a proximal esophageal fistula were performed on 11 dogs under general anesthesia. Following a return of normal bowel function each animal was given 20 cc/kg of a commercial-grade kerosene by gastrostomy tube. The dogs were randomly divided into two groups for necropsy at 24 and at 72 hours, and each dog had chest radiographs prior to instillation of the kerosene and at 6, 24, 48, and 72 hours, depending on their group. The dogs were given an overdose of barbiturate for euthanasia. Tissue was randomly selected from the lungs and examined using standard microscopic and histologic techniques. No clinical complications were observed in any of the animals following the kerosene instillation. No radiologic or histologic evidence of pulmonary changes due to kerosene was found. The lack of pulmonary pathologic changes following kerosene ingestion in dogs protected from aspiration suggests that the treatment for kerosene poisoning should be confined to supportive measures. Induction of emesis is contraindicated in the management of hydrocarbon ingestion.
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A role for calciferol in zinc homeostasis was investigated by radioisotope uptake and compartmental analysis techniques. cholecalciferol was injected into rats 4-5 days prior to radioisotopic study of rapidly exchangeable pools (< 4 h). Kidney, liver, and duodenum had significant increases in zinc uptake rates. Bone and skeletal muscle had significant decreases. No other tissues had significant differences. Compartmental analysis models generated by the SAAM-25 digital computer program suggested a decrease in the fractional tissue to plasma coefficient to be the mechanism for the observed changes in the serum zinc concentration and tissue zinc accumulation rates. It is not clear whether this is a specific effect of calciferol on zinc homeostasis or is a nonspecific response which may reflect some role for zinc in calciferol metabolism.
A 68-year-old white male patient suffering from Paget's disease of bone developed a sarcoma in the sacroiliac region during treatment with calcitonin. There was no evidence of its presence before treatment. Progression of the sarcoma did not appear to be influenced by calcitonin therapy.
The fate of crystals in the parenchymatous sheaths around vascular bundles in alfalfa leaves was followed through the bovine digestive tract by scanning electron microscopy. The bundle and sheath pass from the rumen largely intact. Most crystals are released from the bundle sheath postruminally. In feces, some crystals appear partially eroded and others are intact. By energy-dispersive x-ray analysis calcium is the primary crystal cation. Intact cyrstals isolated from alfalfa leaves by low-temperature ashing and from bovine feces by washing and differential specific gravity were subjected to Raman microprobe analysis. Most crystals were calcium oxalate, a few were potassium oxalate, and some contained both compounds. From 20 to 33% of calcium in alfalfa is in the form of oxalate and apparently unavailable to ruminants. Carbonate is probably in partially eroded crystals from feces. Data presented account for the poorer utilization by cattle of calcium from alfalfa than that from inorganic sources.
A patient with adult-onset insulin-requirging diabetes mellitus had persistent severe local reactions to all available insulins of animal origin. Skin reactions were biphasic in nature with both immediate and late characteristics. An extensive immunologic investigation of this problem was undertaken, revealing evidence of reaginic antibody involvement in the reactions. Routine histologic studies suggested the possibility that Arthus-type mechanisms played a part, although this impression was not confirmed by immunofluorescent microscopy. A program of medical management provided some relief of symptoms.
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