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Biomedical subjects

D J Alexander

Publications and source records attributed to D J Alexander.

197 records · Page 11Linked to original sources
PubMed1970

Growth in chick chorioallantoic membranes of strains of Newcastle disease virus of differing virulence.

The growth of eight strains of Newcastle disease virus in chick embryo chorioallantoic membranes was studied by comparing, at different times after infection, the amounts of haemagglutinin released into the allantoic fluid (extracellular haemagglutinin) with that associated with the membrane (cell-associated haemagglutinin). The virulence of the strains examined differed in that some killed chick embryos more rapidly than others. All strains released similar amounts of extracellular haemagglutinin and maximum titres were achieved about 12 hr. after infection. With virulent strains cell-associated haemagglutinin titres increased exponentially until the death of the host and maximum titres were much higher than those of extracellular haemagglutinin. With avirulent strains cell-associated haemagglutinin titres increased exponentially for only a limited time and titres were always lower than the titres of extracellular haemagglutinin.Similar results were obtained when the titres of neuraminidase and viral ribo-nucleoprotein were measured during the growth of two virulent and two avirulent strains. Virulence appears to be associated with the continued intracellular accumulation of viral antigens.

Allantoin↗
PubMedDate not supplied

Effects of inhalation exposure to hexachlorocyclopentadiene on rats and monkeys.

Hexachlorocyclopentadiene (Hex or C-56) is a highly reactive intermediate used in the production of some insecticides, flame retardants, and resins. The present study was conducted to evaluate the inhalation toxicity of high-purity Hex (97.7%) in rats and monkeys to provide information on the potential hazards of accidental exposure of workers to Hex vapors. Acute, range-finding (14-d), and subchronic (90-d) inhalation studies were conducted with Sprague-Dawley rats and subchronic (90-d) inhalation studies were conducted with cynomolgus monkeys. Both acute and range-finding studies with rats showed a steep dose-response curve, and male rats were more sensitive than females. In the range-finding study with rats the threshold of toxicity for Hex was 0.11-0.5 ppm. Histopathologic examination on rats in the 0.5 ppm group revealed lesions in the olfactory and bronchiolar epithelium and inflammatory exudate in the lumens of the respiratory tract; these changes were consistent with observed impaired respiratory function, confirming the lung as the main target organ. Recovery and regression of lung lesions in rats were noted 2-3 wk after termination of exposure. In the 90-d study, inhalation of Hex vapors at concentrations up to 0.2 ppm for 6 h/d, 5 d/wk, produced no detectable physical or clinical effect and no remarkable gross or histological alterations in rats or monkeys.

Animals↗
PubMedDate not supplied

Spontaneous transpyloric migration of a ballooned nasojejunal tube: a randomized controlled trial.

BACKGROUND: Spontaneous transpyloric migration of a simple nasojejunal tube (NJT) can be expected in only one-third of insertions. Guidance of the tube by radiologic or endoscopic maneuvers is usually required. We believed that locating a 5-mL balloon near the tip of an NJT on which natural peristalsis could act would improve the rate of spontaneous transpyloric migration and facilitate small bowel propagation. METHODS: Thirty healthy volunteers were randomly assigned to have an inflated or noninflated, ballooned NJT fashioned from a modified 9F Hickman line catheter inserted. The pH of aspirates was measured hourly and the final location of the tube assessed by gastrografin contrast abdominal x-ray (AXR) at the end of 6 hours, at which time the tube was removed. RESULTS: After 6 hours, spontaneous transpyloric migration occurred in 86.6% of the ballooned and 66.6% of the nonballooned tubes. The final disposition of the ballooned tubes was: stomach, 2 (13.3%); duodenum, 1 (6.7%); and small bowel, 12 (80%). The final disposition of the nonballooned tubes was: stomach, 5 (33%), NS; duodenum, 9 (60%), p < .05; and small bowel, 1 (6.7%), p < .05. CONCLUSIONS: Ballooned NJT have a higher rate of spontaneous transpyloric migration and are significantly more likely to achieve an optimal small bowel location.

Adolescent↗
PubMedDate not supplied

Sleep onset latency and distress in hospitalized children.

A strategy to promote night sleep was tested in 94 hospitalized 3- to 8-year-old children. Parents were not present at bedtime with the first three of four groups of children who: listened to a parent-recorded story, a stranger-recorded story, or did not listen to a recorded story. The fourth group had parents present at bedtime and the children did not listen to a recorded story. Hypotheses were tested with three dependent variables: a) length of sleep onset latency (SOL), b) incidence of distress, and c) self-soothing behaviors. Length of SOL on Night 2, adjusted for Night 1 length of SOL and observer, showed significant treatment effects. The parent-recorded story group had significantly longer SOL than the other three groups. The group with parents present at bedtime had significantly longer SOL than the no-story group which was not significantly different from the stranger-recorded story group. Distress behaviors on Night 2, adjusted for distress on Night 1, age, and observer, showed significant differences between groups. The parent-recorded story group had a higher incidence of distress behaviors than the other groups; the difference between the parent-recorded and the stranger-recorded group was significant. No significant differences between groups were seen in self-soothing behaviors.

Child↗
PubMedDate not supplied

Characterization of Newcastle disease virus (avian paramyxovirus-1) isolated from pigeons.

Newcastle disease virus (avian paramyxovirus-1) was isolated from pigeons in 12 states between May 1984 and December 1985. One of the isolates was from a feral pigeon; the remainder were from privately owned pigeon lofts. Use of monoclonal antibodies showed seven of the eight isolates tested to be indistinguishable from the 1982 and 1983 Great Britain and European isolates. Clinical signs were paralysis, torticollis, tremors, incoordination, and death. Pigeons inoculated with the paramyxovirus-1 isolates intravenously or intramuscularly developed clinical disease identical to that described for natural infection; however, only one pigeon inoculated intranasally developed clinical signs. The mean death time for inoculated pigeons was 9.5 days, with a range of 4 to 25. Virus was shed for up to 20 days. Primary lesions observed on necropsy were gastroenterocolitis and pancreatic necrosis. Chickens experimentally infected by the cloacal, intranasal, or caudal thoracic air-sac route remained healthy. However, the intracerebral pathogenicity index (ICPI) in day-old chickens was similar to that observed with velogenic Newcastle disease virus isolates. Four of six isolates inoculated intravenously into 6-week-old chickens induced neurotropic disease.

Animals↗
PubMedDate not supplied

Hepatic artery aneurysm: an unusual presentation.

The natural history of visceral artery aneurysms, and in particular those of the hepatic artery, is unclear. The clinical presentation can include upper abdominal pain, bleeding into the gastrointestinal tract, and obstructive jaundice. We present the case of a middle-aged woman with right upper quadrant pain and a palpable mass, in whom a thrombosed hepatic artery aneurysm was found to be the cause.

Abdomen, Acute↗
PubMedDate not supplied

Use of virulence index tests for avian influenza viruses.

The intravenous and intracerebral pathogenicity index tests normally used for Newcastle disease virus isolates were used to measure the virulence of 13 avian influenza viruses. The tests allowed quantitative measurements of the virulence of the avian influenza viruses, and the results confirmed the range in virulence, between the two extremes, of the avian influenza viruses and demonstrated the lack of correlation between virulence and antigenic type.

Animals↗