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1.
R S Chadwick J Ohayon M Lewkowicz 《Proceedings of the National Academy of Sciences of the United States of America》1989,86(9):2996-2999
A fluid-fiber-collagen stress tensor is used to describe the rheology of the left ventricle of the heart. Linear theory is used to find the equilibrium solutions for the end-diastolic and end-systolic states of general axisymmetric shapes that are small perturbations of a thick-walled finite cylinder. The general problem can be studied by superposing the effects of variable midwall radius but constant wall thickness with those of variable wall thickness but constant midwall radius. A Fourier series representation is used to describe the midwall radius and thickness functions. Numerical calculations are performed to determine the deformed geometry and spatial distributions of tissue pressure, stresses, and fiber strains. The calculations proved to be highly accurate when compared to an analytical solution obtained for the special case of no fibers. The results show significant longitudinal differences when compared to results for the cylindrical geometry, with more sensitivity to variation in wall thickness than to variation in midwall radius. 相似文献
2.
B A Sommerville C G Scanes R Swaminathan A D Care S Harvey A Chadwick 《General and comparative endocrinology》1989,76(2):261-266
An experiment was carried out to investigate the effect of a range of estradiol (E2) doses (0.1-6.5 micrograms/g body wt/day) on vitamin D metabolism and the plasma levels of growth hormone (GH) and prolactin (PRL) in the growing chick. Doses of 0.5-0.7 microgram/g E2, which are insufficient to raise the plasma calcium level, did induce an increase in growth rate, an increase in 25-hydroxyvitamin D 1 alpha-hydroxylase (1-hydroxylase) and 24-hydroxylase activities, and an increase in plasma GH level. These parameters leveled off or fell over the dose range 1-2 micrograms/g E2 but there was evidence of a second peak in 1-hydroxylase activity at 6 micrograms/g E2. At this high dose rate, the plasma Ca level rose to 8 mM, as it does in the laying hen; 24-hydroxylase activity, growth rate, and plasma GH and plasma PRL levels all decreased. It was concluded that the dose response to estrogen in the growing chick is not linear and, in the case of 1-hydroxylase activity, may even be biphasic. 相似文献
3.
Sanjay Sisodiya J Helen Cross Ingmar Blümcke David Chadwick John Craig Peter B Crino Paul Debenham Norman Delanty Frances Elmslie Mark Gardiner Jeffrey Golden David Goldstein David A Greenberg Renzo Guerrini Michael Hanna John Harris Paul Harrison Michael R Johnson George Kirov Dimitri M Kullman Andrew Makoff Carla Marini Rima Nabbout Lina Nashef Jeffrey L Noebels Ruth Ottman Munir Pirmohamed Asla Pitk?nen Ingrid Scheffer Simon Shorvon Graeme Sills Nicholas Wood Sameer Zuberi 《Epileptic Disord》2007,9(2):194-236
The Sixth Epilepsy Research Foundation workshop, held in Oxford in March 2006, brought together basic scientists, geneticists, epidemiologists, statisticians, pharmacologists and clinicians to consider progress, issues and strategies for harnessing genetics to improve the understanding and treatment of the epilepsies. General principles were considered, including the fundamental importance of clear study design, adequate patient numbers, defi ned phenotypes, robust statistical data handling, and follow-up of genetic discoveries. Topics where some progress had been made were considered including chromosomal abnormalities, neurodevelopment, hippocampal sclerosis, juvenile myoclonic epilepsy, focal cortical dysplasia and pharmacogenetics. The ethical aspects of epilepsy genetics were reviewed. Principles and limitations of collaboration were discussed. Presentations and their matched discussions are produced here. There was optimism that further genetic research in epilepsy was not only feasible, but might lead to improvements in the lives of people with epilepsy. 相似文献
4.
D R Sandeman A P Sandeman P Buxton H H Hughes D W Chadwick I R Williams R D Baker P M Foy D M Shaw 《British journal of neurosurgery》1990,4(4):299-312
The management of patients presenting with supratentorial glioma between 1978 and 1986 is reviewed. Complete follow-up in 517 cases was obtained. One hundred and fifty eight patients were not submitted to any form of surgery, 299 patients were biopsied and 60 patients underwent craniotomy and internal decompression. The no surgery group contained a higher proportion of patients with poor prognostic indicators than either the biopsy or craniotomy groups. The craniotomy group consisted of patients with better prognostic indicators than the biopsy group, in particular, younger age and more favourable site, type and grade of tumour. This was reflected in the difference in outcome between the groups. Median survival was 14 months in the craniotomy group, four months in the biopsy group and 2.2 months in the no surgery group. The outcome in patients with histologically proven malignant gliomas was best in those patients who received radiotherapy. The craniotomy group had a median survival of 18.5 months, a two year survival of 48% and a five year survival of 9%. The median survival following radiotherapy of those patients with proven malignant gliomas who had a biopsy was 9.5 months with a two year survival of 16% and a five year survival of 2%. These results compare favourably with studies which have adopted a more aggressive approach, suggesting that outcome is determined as much by patient selection using favourable prognostic indicators as by the treatment itself. The need for prospective trials of the management of unselected consecutive glioma patients randomizing them to conservative and radical treatment groups in order to define the role of both conventional therapy and radical therapy is discussed. 相似文献
5.
Kevin O'Brien Jean Wright Frances Conboy YeWeng Sanjie Nicky Mandall Stephen Chadwick Ivan Connolly Paul Cook David Birnie Mark Hammond Nigel Harradine David Lewis Cathy McDade Laura Mitchell Alison Murray Julian O'Neill Mike Read Stephen Robinson Dai Roberts-Harry Jonathan Sandler Ian Shaw 《American journal of orthodontics and dentofacial orthopedics》2003,124(3):234-43; quiz 339
This study evaluated the effectiveness of early orthodontic treatment with the Twin-block appliance for the developing Class II Division 1 malocclusion. This multicenter trial was carried out in the United Kingdom. A total of 174 children, aged 8 to 10 years old, with Class II Division 1 malocclusion were randomly allocated to receive treatment with a Twin-block appliance or to an untreated, control group. Data were collected at the start of the study and 15 months later. Results showed that early treatment with Twin-block appliances resulted in reduction of overjet, correction of molar relationships, and reduction in severity of malocclusion. Most of this correction was due to dentoalveolar change, but some was due to favorable skeletal change. Early treatment with the Twin-block appliance is effective in reducing overjet and severity of malocclusion. The small change in the skeletal relationship might not be considered clinically significant. 相似文献
6.
J. Plotnikova M. Krichevsky K. H. Chadwick G. Eitner H. F. Linskens 《Pediatric radiology》1991,21(8):599-599
7.
A simple, precise method has been developed for assessing neutrophil secretory responses (release of vitamin B12 binding protein from specific granules) to challenge of aliquots of whole blood with the bacterial chemotactic peptide N-formylmethionyl-leucyl-phenylalanine (fMLP). Dose-response studies performed on blood from normal healthy volunteers showed higher maximal secretory responses in males than females (33.3 +/- SEM 2.2 vs. 27.4 +/- 2.5, P less than .005) a left shift in dose-response curves after feeding compared to fasting (P less than .005), spontaneous up-regulation of responses in blood incubated at 37 degrees C for 1 h, and marked upregulation in response to preincubation with endotoxin. This whole blood challenge method may be used to study neutrophil responses in groups of individuals or patients without the confounding effects of changes in cell responses resulting from cell isolation procedures. The method may also be used as a bioassay for neutrophil-activating factors. 相似文献
8.
Caporale CM Capasso M Lucani M Gandolfi P De Angelis MV Di Muzio A Caporale V Uncini A . 《Journal of the peripheral nervous system : JPNS》2004,9(2):114-115
Campylobacter jejuni (C. jejunj) infection is the most common antecedent in the axonal variant of Guillain‐Barré syndrome (GBS). Antibodies against nerve gangliosides found in GBS patients recognize cross‐reactive epitopes in the lipopolysaccharide (LPS) of C. jejuni. This led to the molecular mimicry hypothesis of GBS. We immunized eleven rabbits with a LPS extracted from HS:19 C. jejuni strain isolated from a patient with GBS and complete Freund's adjuvant (CFA)(group I). In a second experiment we immunized seven rabbits with LPS, CFA and keyhole limpet hemocyanin (KLH)(group II). All group I rabbits developed high titers of anti‐LPS, anti‐GM1, anti‐GD1b antibodies and lower titers of anti‐GD1a. One rabbit, 50 days after initial inoculation, showed tremor and weakness. All rabbits of group II developed high titres of antiganglioside antibodies and six animals showed weakness 59–113 days after initial inoculation. Two rabbits died. Pathology showed mild to moderate, tendentially grouped, axonal degeneration in sciatic nerves of four out of five animals. Control rabbits of group I (immunized with CFA only) did not develop antibodies, controls of group II (immunized with CFA + KLH) developed low titers of IgG anti‐GM1. None developed neurological signs or showed axonal degeneration. C. jejuni LPS is a potent B‐cell stimulator capable to induce a strong antiganglioside response in rabbits. However, to induce the neuropathy is crucial to employ KLH, a glycoprotein known to stimulate both humoral and cellular responses. This animal model reproduces the pathogenetic process hypothesized in axonal GBS with antiganglioside antibodies post C. jejuni infection. 相似文献
9.
Continuous proteolysis resulting in consumption of major cytoskeletal proteins may be essential for platelet activation and aggregation. In this study we evaluated the effect of a known protease inhibitor, Leupeptin, on agonist induced platelet aggregation and secretion. Platelets exposed to 10 ugs/ml of Leupeptin did not aggregate in response to the action of thrombin (0.2u/ml). However, a concentration of Leupeptin as high as 250 ugs/ml did not prevent arachidonate induced aggregation and secretion. Leupeptin (100 ugs/ml) effectively blocked thrombin (0.2 u/ml) induced elevation of cytosolic calcium, but did not affect arachidonate induced elevation of platelet intracellular calcium levels. At a concentration of 100 ug/ml, Leupeptin effectively blocked thrombin (0.5u/ml) induced clot formation of platelet poor plasma, suggesting that it can exert its effect on thrombin by preventing fibrinogen degradation. Effective Ki for the competitive inhibition of thrombin induced hydrolysis of a chromogenic substrate, S2238, by Leupeptin was 2.4 uM. Leupeptin inhibition of platelet function was reversible by washing platelets free of the polypeptide. Results of our study demonstrate that Leupeptin inhibits thrombin induced platelet activation, probably by interfering with its proteolytic activity on the platelet surface membrane. However, inhibition of platelet surface membrane associated proteases did not prevent activation of platelets by other agonists. 相似文献
10.
Stephen M Chadwick David R Bearn Alan C Jack Kevin D O'Brien 《European journal of dental education》2002,6(2):57-63
This paper explores some modern concepts of teaching and learning, including cognitive theory, the zone of proximal development, constructivism, andragogy and learning styles and describes how they have informed the development of an undergraduate orthodontic curriculum. The changes described include student-centred learning, guided self-learning, and the incorporation of problem-based learning concepts. The details of the problem-based learning programme are described together with results of student feedback on the change in teaching and learning style. 相似文献