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Biomedical subjects

J Pearce

Publications and source records attributed to J Pearce.

At least 37 records · Page 2Linked to original sources
PubMed1987

The effect of mediastinal irradiation on cardiac function of patients treated during childhood and adolescence for Hodgkin's disease.

To determine the frequency of cardiac dysfunction in patients treated during childhood or adolescence with mediastinal irradiation for Hodgkin's disease (HD), 28 patients underwent cardiac evaluation 19 to 182 months (median, 90 months) after the completion of radiation therapy. No patient had symptoms of cardiac disease. All were normotensive. All patients had a normal cardiothoracic ratio. There were no abnormalities of voltage or rhythm in the ECGs. The left ventricular end diastolic volume was increased in 19.2% of patients, none of whom had evidence of impaired left ventricular function. The left ventricular ejection fraction (LVEF) was increased in 15.3% of patients. No patient had a decreased LVEF. Pericardial thickening was demonstrated on echocardiograms from 12 of 28 patients (42.9%). Thickening was more frequent among those patients observed for 72 or more months (47.1%; eight of 17) than among those with shorter periods of follow-up (36.4%; four of 11). This study demonstrates that cardiac dysfunction is an infrequent sequela of mediastinal irradiation following treatment using an equally weighted, anterior-posterior technique. Longitudinal study of these patients will be necessary to determine the clinical significance and evolution of the occult pericardial thickening that was identified.

Adolescent↗
PubMed1986

Intramembranous organization of lobster excitatory neuromuscular synapses.

The fine structure of identified neuromuscular synapses of the single excitatory axon to the distal accessory flexor muscle in lobster limbs was examined with freeze-fracture and serial thin-section electron microscopy. The latter technique reveals presynaptic dense bars with synaptic vesicles aligned on either side of these bars and often fused to the membrane, suggesting exocytosis and confirming our previous contention that these bars are active zones of transmitter release. The intramembranous organization of these active zones, as revealed in freeze-etched tissue, is a ridge-like elevation of the P-face of the axolemma with a matching trough on the complementary E-face. The ridge on the P-face has rows of large scattered intramembranous particles along the apex and is often bordered by a series of small, circular depressions which are presumed to represent exocytotic vesicles attached to the presynaptic membrane. Complementing these depressions are a few volcano-like protuberances seen occasionally on the E-face membrane. Because such evidence for transmitter release occurred in both stimulated and non-stimulated preparations, it demonstrates that chemical fixatives employing aldehydes induce transmitter release. The postsynaptic receptor sites of these excitatory synapses are characterized by oval-shaped patches of densely packed particles on the E-face, arranged in a random pattern on the sarcolemma. The complementary P-face view exhibits a regular square array of particle imprints or pits.

Aminopyridines↗
PubMed1986

Antibody levels to Mycoplasma pneumoniae in sera collected from healthy blood donors of Wellington, New Zealand, during 1976-80.

The sera of healthy blood donors from the Wellington area of New Zealand, collected between 1976 and 1980, were analysed by the complement fixation test for antibody to Mycoplasma pneumoniae. A high prevalence of antibody to this organism was demonstrated and the occurrence of an M. pneumoniae epidemic in New Zealand within the survey period was shown to be reflected in the immune status of this healthy adult population. This would suggest that during an epidemic many people within the Wellington community may have M. pneumoniae infections involving little overt illness.

Adolescent↗
PubMed1986

Failure of oestradiol administration to induce fatty liver haemorrhagic syndrome in the laying hen.

Studies were carried out to investigate whether the administration of oestradiol to laying hens induced fatty liver-haemorrhagic syndrome (FLHS). Short term oestradiol administration (up to 6 d) significantly increased liver size and plasma lipid concentration but had no effect on liver lipid concentration or hepatic lipogenic enzyme activities. Longer-term hormone treatment (up to 28 d) again significantly increased liver size and plasma lipid concentration. Liver lipid concentration was substantially reduced and lipogenic enzyme activity significantly reduced in oestradiol-treated birds. These effects had some similarities to those seen in oestrogenised immature birds and were additive to the effects of endogenous oestrogen in the laying bird. There were no deaths from FLHS and oestradiol treatment did not cause liver haemorrhages or affect egg production.

Animals↗
PubMed1986

Surgical correction of lesions affecting the second portion of the vertebral artery.

Substantial controversy has surrounded the diagnosis and management of vertebrobasilar ischemic events, with no consensus on the value of medical or surgical treatment of patients symptomatic with brain stem ischemia who have angiographically proven vertebral artery lesions. This report presents our experience with the surgical treatment of 12 of 88 patients with angiographically verified lesions in the vertebral artery who were symptomatic for 1 to 12 months before their evaluation. None experienced symptomatic relief with antiplatelet agents, nor did the administration of anticoagulants in 4 of the patients provide any benefit. The lesions included bilateral vertebral artery occlusion with distal reconstitution through muscular collaterals in 6 patients, unilateral vertebral artery hypoplasia with contralateral long-tailed lesions from the vertebral artery origin to C-5 in 3 patients, and severe bilateral vertebral artery origin lesions extending beyond the C-5 level in 3 patients. A vertebral endarterectomy and vertebral-carotid transposition in the second portion of the artery were successfully used to reestablish flow and obtain symptomatic relief in 10 of the 12 cases; 1 of these procedures had to be redone because of a persistent stenosis at C-4. Another patient had a saphenous vein graft from the common carotid to the vertebral artery at C-5. The remaining patient had an anastomosis of the distal external carotid to the vertebral artery at C-3, but this failed and an anastomosis of the occipital artery to the anterior inferior cerebellar artery had to be completed to reestablish flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1985

Enhanced reappearance of fast fibers in regenerating crayfish claw closer muscles.

In the pristine claws of adult crayfish the muscle fibers of the closer are all of slow type as judged by sarcomere lengths of greater than 6 micron, and a uniform degree of myofibrillar ATPase activity. In regenerating claws of mature and immature crayfish, the muscle has a central band of fast type fibers as characterized by shorter sarcomeres (less than 6 micron) and a higher degree of ATPase activity than the surrounding slow fibers. During primary development, the closer muscle has a fiber composition similar to that of the regenerating muscle except for a smaller proportion of fast fibers. Thus the reappearance of fast fibers during regeneration recapitulates ontogeny while their enhanced proportions may reflect epigenetic influences such as restriction of nerve-mediated muscle activity in the limb bud.

Adenosine Triphosphatases↗
PubMed1985

Growth-related features of lobster neuromuscular terminals.

Neuromuscular terminals of the low-output type formed by the single excitor axon to the limb distal accessory flexor muscle in the lobster Homarus americanus were studied with serial section electron microscopy. This type of innervation was compared between a small and a large lobster where a two-fold difference in mean quantal content of synaptic transmission was found. Several growth-related changes in the fine structure of these low-output synaptic terminals were seen. First, there was a proliferation of multiterminal innervation consisting of an increase in the number of nerve terminals, synapses and presynaptic dense bars between the small and large lobster. Also the mean surface area of the synapses increased significantly in the large compared to the small lobster. Second, synapses possessed distinct areas of non-specialized membrane or perforations which showed a growth-related increase in their number per synapse between small and large lobsters. Such perforations also occurred in the high-output synapses but only amongst the larger synapses of the older lobster. It is proposed that these perforations subdivided synapses into smaller functional units for membrane recycling as they provide a ready source of non-synaptic axolemma for nearby active sites (dense bars). Third, the branch point between subsidiary and principal terminals as well as the ending of a terminal is composed of synaptic membrane which is presumably involved respectively in the sprouting and elongation of nerve terminals during growth. Altogether these observations signify both qualitative and quantitative changes in identified neuromuscular terminals with growth.

Animals↗
PubMed1985

A comparison of the effects of duodenal glucose infusion on carbohydrate and lipid metabolism in liver, adipose tissue and small intestinal mucosa in sheep.

The effects of duodenal glucose infusion on the specific activities of some enzymes of carbohydrate and lipid metabolism in the liver, perinephric adipose tissue and small intestinal mucosa of sheep were examined. Lipogenic enzyme activity was generally greatest in adipose tissue and lowest in liver and the response of these enzymes to glucose infusion was similarly greatest in adipose tissue. Glycolytic enzyme activity was significantly increased in all three tissues following duodenal glucose infusion. The effects of increasing carbohydrate availability in the small intestine in relation to tissue metabolism in sheep are discussed.

Adipose Tissue↗
PubMed1985

Lead encephalopathy. A case report and review of management.

Acute lead encephalopathy has become a rare syndrome in the United States. Early recognition of the disease, with institution of specific chelation therapy, is critical in order to minimize mortality and morbidity. Lead intoxication, however, may mimic other more common diseases. We report an 8-year-old child with known sickle cell anemia who presented initially with findings suggestive of vaso-occlusive crisis but who deteriorated rapidly and was found to have severe lead poisoning. We present her hospital course and review the management of lead encephalopathy in detail.

Anemia, Sickle Cell↗
PubMed1985

Complications of cerebral revascularization with autogenous vein grafts.

Autogenous veins were used for cerebral revascularization 29 times. There were 17 long grafts to the cortex and 12 shorter grafts for reconstruction of cervical vessels. Of the long cortical grafts, 5 occluded and 3 patients developed intracerebral hemorrhage. With the shorter grafts, all remained patent and there were no hemorrhagic complications. A combination of a relatively low flow rate and endothelial damage in the graft was thought to be largely responsible for early graft failure. Revascularization of an infarct and hypertension were implicated in cases with intracerebral hemorrhage.

Cerebral Angiography↗
PubMed1985

Acute cerebral revascularization.

Fifteen patients evaluated for acute cerebral ischemia underwent acute cerebral revascularization between March, 1979, and May, 1983. Clinical presentation included crescendo transient ischemic attacks (TIA's) in eight cases, progressing neurological dysfunction in three cases, and completed nonfluctuating deficits in four cases. Nine patients received intravenous heparin but did not improve neurologically. The patients with crescendo TIA's were operated on within 4 hours of their last event; those with progressing deficits were operated on while the deficit was developing, and those with established deficits were operated on 4, 6, 9, and 12 hours, respectively, after the event began. The clinical picture for 10 patients had resolved within 10 hours after surgery. One patient with crescendo TIA's, two with progressing deficits, and two with established deficits had postoperative residual deficits, of which three were mild and two severe. One patient, who had a saphenous vein graft to the middle cerebral artery, developed an intracerebral hematoma. In this prospective noncontrolled nonrandomized study, acute cerebral revascularization was performed safely, had limited risks, and offered the potential to help some patients. Further controlled randomized studies are indicated.

Adult↗
PubMed1979

Lactate administration and fatty liver and kidney syndrome development in biotin-deficient chicks.

Two experiments were carried out to determine whether administration of lactate to biotin-deficient chicks induced fatty liver and kidney syndrome (FLKS). 2. The results suggest that increased serum lactate concentrations are a consequence of the syndrome rather than a contributory factor in its incidence. 3. The increase in liver lipids of birds affected by FLKS was not associated with an increase in the specific activity of the hepatic lipogenic enzyme acetyl CoA carboxylase accept when birds developed FLKS spontaneously in experiment 2. 4. Some biotin-deficient chicks did not show physical symptoms of deficiency although mean liver biotin concentrations were low (0.31 microgram/g liver).

Acetyl-CoA Carboxylase↗
PubMed1979

Values education: extending the view.

A number of values education strategies have recently been developed for use in the classroom. The Shaver model described here incorporates a rational decision-making process based on basic moral values. That process involves identifying and clarifying values, value labeling and generalization, examining the possible consequences of value decision, recognizing and resolving value conflict, and forming qualified decisions. It is not, however, necessary to proceed through that exact sequence of steps. For example, values discussion may begin with the teacher helping a students to recognize a value conflict. From that point, the discussion may move the identification and labeling of values. Consequently, there is flexibility in how this model may be used in the classroom. This model is developed on the premise that people who use such a process in making decisions relating to social-ethnical issues enhance their functioning within a democratic society. It is suggested that people who utilize this process in relation to health issues can likewise enhance the effectiveness of their health-related decisions. Hopefully, there will be a yield of postive health behaviors.

Child↗
PubMed1978

Biotin deficiency and liver metabolism in relation to fatty liver and kidney syndrome.

Varying degrees of biotin deficiency were induced by adding freeze-dried, raw egg white to the diet of broiler chicks. Aspects of liver metabolism were studied with reference to fatty liver and kidney syndrome. Mortality was low with 11.8 g egg white/kg diet, or less, but with 17.7 g/kg or more, mortality was very high. High mortality was observed with less than 0.33 microgram biotin/g liver. Associated with low concentrations of liver biotin were substantial increases in liver weight and lipid content in starved birds. The increased liver lipid content was not observed in birds fed ad libitum. The increased liver lipid content in biotin-deficient, starved birds was not reflected in the specific activities of hepatic lipogenic enzymes or hepatic lipogenesis in vivo measured by the incorporation of tritium from 3H-labelled water into liver lipid. Biotin deficiency affected the specific activities of the biotin-requiring enzymes, pyruvate carboxylase and acetyl CoA carboxylase, differently; the latter was unaffected whereas the former decreased concomitantly with liver biotin concentration.

Animals↗