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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↗
PubMed1984

The effects of duodenal glucose and dextrin infusion on adipose tissue metabolism in sheep.

Three groups of 3 sheep were penned individually and provided with pelleted dried grass. In addition two of the groups received either dextrin or glucose via duodenal cannulae. The rate of in vitro lipogenesis, from acetate of glucose, in subcutaneous adipose tissue was significantly increased in the carbohydrate-infused sheep. The increase in lipogenesis in response to glucose infusion was much greater than that to dextrin infusion. The changes in lipogenesis induced by dextrin or glucose infusion were reflected in the specific activities of the various lipogenic enzymes examined. These results are discussed in relation to the capacity of the sheep small intestine to hydrolyse alpha-linked glucose polymer.

Acetates↗
PubMed1984

Surgical reconstruction of the proximal vertebral artery.

The authors have reviewed their experience in the management of 55 patients admitted to Henry Ford Hospital with symptoms of vertebrobasilar insufficiency and associated proximal vertebral artery stenosis or occlusion. In 48 patients, the symptoms occurred as multiple repeated events, five of which resulted in permanent deficits. The remaining seven patients had single events, four of which caused permanent deficit. These patients had been treated unsuccessfully with antiplatelet agents (37 cases) and with anticoagulant drugs (15 cases) before surgery. Most patients had multiple angiographic abnormalities, including bilateral vertebral stenosis in 19 cases, unilateral vertebral stenosis and contralateral occlusion in 18, unilateral vertebral hypoplasia and contralateral stenosis in 10, subclavian artery stenosis with steal in seven, and bilateral vertebral artery occlusion in one case. Posterior communicating arteries could not be demonstrated angiographically in 18 patients. Thirty-four patients had associated stenotic or occlusive lesions of the internal carotid artery. Forty-eight underwent a vertebral-to-carotid artery transposition. Of these, 18 had an associated carotid endarterectomy and seven had a vertebral artery endarterectomy immediately before the transposition. Two patients had saphenous vein grafts, one from the subclavian and one from the common carotid artery to the vertebral artery. Other surgical procedures included vertebral artery ligation in one case, transposition of the vertebral artery to the thyrocervical trunk in two cases and to the subclavian artery in one case, and endarterectomy of the origin of the vertebral artery in one case. All but two patients had complete resolution of their symptoms: one had persistent dizziness and the other had syncopal episodes. Complications included transient Horner's syndrome (30 cases) which became permanent in four cases, vocal cord paralysis (three cases), elevated hemidiaphragm without respiratory difficulty (two cases), and superficial would infection (one case). There were no deaths. Although the presentation of patients with vertebrobasilar insufficiency is generally characteristic, we believe that a specific diagnosis can be established only by angiographic means. Anticoagulants have been used to alleviate symptoms in some cases but are ineffective in solving the primary hemodynamic problem. Surgical reconstruction of the affected area deserves further evaluation in the management of these patients.

Adult↗
PubMed1983

Comparison of standard tube and microagglutination techniques for determining Brucella antibodies.

A microagglutination method for determining the agglutinating and "blocking' antibodies to Brucella abortus is described. A collection of sera from healthy blood donors in two rural areas of New Zealand were tested by the microagglutination methods and the standard methods in tube. The results are compared and show that where discrepancies occur, these are due to the microagglutination methods being more sensitive. It is concluded that these are suitable methods for screening populations.

Agglutination Tests↗
PubMed1983

The effects of dietary intake and of dietary concentration of copper sulphate on the laying domestic fowl: effects on laying performance and tissue mineral contents.

Sixty white hybrid (Shaver 288) laying hens were subjected to three main dietary regimens for 5 d: ad libitum feeding of control and CuSO4-supplemented diets, force-feeding these same diets to the same intake as that of the ad libitum control diet and pair-feeding the control CuSO4-free diet to intakes equivalent to those of supplemented diets. Final body weight of the force-fed birds was significantly greater than of the other groups. Egg number and weight were significantly reduced as food intake decreased. Liver weight per unit body weight was significantly increased and oviduct and ovary weights/kg body weight were significantly reduced by force-feeding. As food intake decreased kidney and gizzard weights per unit body weight were significantly increased. The concentrations and total contents of Cu and Zn in liver were significantly increased in the ad libitum and force-fed groups. Force-feeding CuSO4-supplemented diets, which eliminated difference in food intake, confirmed that CuSO4 per se affected tissue weights and mineral concentrations as distinct from effects due to the reduced food intake associated with increasing dietary CuSO4.

Animals↗