The effectiveness of foams in bicycle and motorcycle helmets.

The optimisation of the foam used for shock absorption in bicycle and motorcycle helmets is considered. It is shown that for the former, the ideal foam yield stress for impact with a rigid protruding object is higher than that for impact with a deformable flat object. Therefore, the design must be a compromise.

High levels of recombination induced by homologous P elements in Drosophila melanogaster.

P element transposons in Drosophila melanogaster are capable of mobilizing incomplete P elements elsewhere in the genome, and of inducing recombination. This recombination is usually only of the order of 1% or less. We show that two P elements, located at exactly homologous sites, induce levels of recombination of 20% or higher.

Transformation of freshwater and marine caulobacters by electroporation.

We performed plasmid electrotransformation of Caulobacter crescentus strains and obtained up to 3 x 10(8) transformants per micrograms of pKT230. The presence and integrity of the paracrystalline protein surface (S) layer influenced electroporation; caulobacters lacking the S layer were electrotransformed 10 times more efficiently than caulobacters possessing the S layers. A procedure yielding 1,500 transformants per micrograms of pKT230 was developed for a marine caulobacter.

Non-Hodgkin lymphoma of the small intestine.

The authors present a simplified radiographic classification of non-Hodgkin lymphoma involving the small intestine. The classification system is based on radiographic findings in 22 pathologically proved cases of lymphoma involving the small bowel and consists of three major forms: primary, lymphoma complicating celiac disease, and mesenteric nodal. In this series, small bowel lymphoma was evenly distributed in the jejunum and ileum.

Gastrointestinal bleeding due to multiple ileal duplications diagnosed by scintigraphy and barium studies.

A case of multiple ileal duplications presenting with gastrointestinal bleeding is described. Technetium-99m Pertechnetate scintigraphy in conjunction with barium studies provided the initial clue and accurately localised the abnormality pre-operatively.

Appealing denial of payments under Part B of the Medicare program.

Under recently enacted legislation, Congress has given physicians and medical clinics new rights in Part B payment disputes with the Medicare program. Favorable court decisions have also expanded the physician's rights in this area. In addition to an informal review and "fair hearing," physicians may now be entitled, depending on the dates of service in dispute, to an administrative hearing and judicial review of the determination.

Radiological examination of the small bowel.

A retrospective study was made of 100 consecutive dedicated per-oral small bowel examinations. 33% of the studies were abnormal, of which almost half were due to Crohn's disease. When grouped according to clinical suspicion, 73.

Medicare recoupment: a legal and legislative update.

In 1987, the Texas Medical Association and 20 other plaintiffs filed suit against the US Department of Health and Human Services (HHS) over the federal government's effort to recoup $14 million from physicians and patients for alleged overpayments during July 1985 through March 31, 1986. A federal district court judge granted a preliminary injunction that halted the recoupment pending a full hearing on the merits of the case and a decision. In June 1989 the Court of Appeals overturned the district court's decision, and TMA turned to the US Congress for relief.

Glomerular actions of ANG II during reduction of renal artery pressure: a morphometric analysis.

The glomeruli of kidneys subjected to reduced perfusion pressure were examined morphometrically. The left renal artery was narrowed for 30 min in anesthetized dogs with (n = 6) or without (n = 7) converting-enzyme inhibition (captopril). The kidneys were then rapidly fixed by glutaraldehyde perfusion at high flow rate.

Frontal cortical and left temporal glutamatergic dysfunction in schizophrenia.

Glutamatergic mechanisms have been investigated in postmortem brain samples from schizophrenics and controls. D-[3H]Aspartate binding to glutamate uptake sites was used as a marker for glutamatergic neurones, and [3H]kainate binding for a subclass of postsynaptic glutamate receptors. There were highly significant increases in the binding of both ligands to membranes from orbital frontal cortex on both the left and right sides of schizophrenic brains.

Barrett's esophagus: diagnosis by double-contrast esophagography.

A blinded, retrospective study was performed to determine the role of double-contrast esophagography in diagnosing Barrett's esophagus. The study group consisted of 200 patients who had double-contrast esophagrams and endoscopy because of severe reflux symptoms. The radiographs were reviewed by two gastrointestinal radiologists who had no knowledge of the endoscopic findings.

Adenine nucleotides and ventricular fibrillation.

The isolated perfused rat heart was used to study the influence of adenine nucleotides and their metabolites on vulnerability to ventricular fibrillation. In this model the incidence of ventricular arrhythmias after coronary artery ligation is determined by the extracellular K+ concentration; with perfusate K+ of 2.0 and 3.

What is the significance of the abnormal oesophageal scintigram?

In a review of 52 oesophageal scintigrams carried out in 46 patients with a variety of oesophageal problems, there was no correlation between the results of this test and the findings in other tests of oesophageal function, or between the scintigram results and the patients' symptoms, with the possible exception of regurgitation. We conclude that the test is of little value.

Renal responses to angiotensin II in conscious dogs: effects of aspirin and indomethacin.

1. Angiotensin II was infused into the renal artery of unanaesthetized dogs at 0.4 and 2.

Angiotensin II-induced contraction of mesangial cells in acute renal artery stenosis in dogs.

1. Renal artery stenosis was induced in anaesthetized dogs, and the kidney rapidly fixed after 30 min. 2.

Permissive action of potassium on arrhythmogenesis in the rat heart.

The isolated perfused rat heart was used to assess the influence of extracellular potassium ([K+]0) on vulnerability of the heart to ventricular fibrillation (VF). The VF threshold is reduced when [K+]0 is lowered from 5.9 to 2.

Acute large-bowel pseudo-obstruction.

The clinical and radiological features of acute large-bowel pseudo-obstruction occurring in 13 patients over a 7-year period are reviewed. Clinical features included atypical signs and symptoms of large-bowel obstruction and serious concomitant illness, including trauma in 10. The predominant radiological features were gross colonic dilatation, scant fluid levels, a gradual transition to collapsed bowel and a normal gas and faecal pattern in the rectum.