Wall-thickness and midwall-radius variations in ventricular mechanics.

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.     

Effect of estrogen on calcium homeostasis and pituitary hormones in the growing chick

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.     

Genetics of epilepsy: epilepsy research foundation workshop report.

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.     

The management of patients with an intrinsic supratentorial brain tumour

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.     

Effectiveness of early orthodontic treatment with the Twin-block appliance: a multicenter, randomized, controlled trial. Part 1: Dental and skeletal effects.

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.     

Assessment of neutrophil leukocyte secretory response to fMLP in whole blood in vitro.

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.     

FM sonography in diffuse liver disease: prospective assessment and blinded analysis

FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease.