Search PubMed⌕ Search

Biomedical subjects

A D Dayan

Publications and source records attributed to A D Dayan.

At least 55 records · Page 3Linked to original sources
PubMed1987

Alterations in crypt cell populations in the small intestine as an early toxic response to sub-acute ethanol administration.

Crypt cell production was examined in young male rats (Sprague-Dawley) given 1, 5 or 15% ethanol in their drinking water for up to 14 days. Ethanol 1 and 5% did not influence food and liquid consumption and growth was similar to that seen in control animals given tap water only to drink. Animals given 15% ethanol exhibited a significant reduction in food and liquid intake and showed a marked diminution in weight gain within 7 days. Ethanol consumption did not affect the length of the small bowel, but 5 and 15% concentrations inhibited cell production in the jejunum and in the distal aspect of the ileum. The relative position of the proliferative compartment, as assessed by the 50% total mitosis level, was unaltered as a result of the treatment. 1% Ethanol led to an increased mitotic rate in the jejunum after 14 days, treatment. Crypt cell production returned to normal in animals given 5% ethanol for 7 days and then a recovery period of 7 days. Mitotic inhibition resulting from ethanol ingestion is probably due to a direct effect (jejunum and proximal ileum) but systemic changes possibly contribute to changes seen in the distal ileum. The nutritional and toxicological implications of ethanol consumption are discussed.

Animals↗
PubMed1987

Dominant lethal study of ribavirin in male rats.

Ribavirin, a new synthetic antiviral agent, was studied for dominant lethal effects in male CD rats. The drug was administered intraperitoneally at doses of 50, 100 and 200 mg/kg/day for 5 days. Males were mated weekly with 8 consecutive batches of female rats. Marginal increase in early foetal death detected in Assessment Weeks 3 and 8 in females mated with the low-dose and high-dose males were not dose-related and were most probably chance events caused by the particularly low vehicle control frequencies for these 2 weeks. Also, the slightly reduced pregnancy proportion among females mated with the high-dose treated males was to a substantial extent the effect of a single male rate which failed to fertilize any females. Ribavirin was, therefore, regarded as being devoid of any mutagenic potential demonstrable by a rat dominant lethal assay.

Animals↗
PubMed1987

Comparative subacute effects of dietary raw soya flour on the pancreas of three species, the marmoset, mouse and rat.

Subacute changes induced in the pancreas by raw soya flour have been studied in three species. The raw soya flour was fed to male Sprague-Dawley rats and male CD-1 mice for 2, 4 or 8 days at a level of 50% (w/w) in the diet, and to male and female marmosets for 2 or 7 days at 20% (w/w) in the diet. The stathmokinetic method was used to study mitotic activity in the pancreas, and mean acinar cell area was calculated using an image analysis system. The relative weight of the pancreas in the rat and mouse increased during dosing, but that of the marmoset did not. No proliferative or trophic effects were observed in marmoset pancreas, but in both the mouse and rat a transient increase in mitotic activity was followed by a steady increase in acinar cell size.

Animals↗
PubMed1987

Evaluation of the BTS approach to the testing of substances and preparations for their acute toxicity.

This study has shown that the new approach to acute oral toxicity testing proposed by the British Toxicology Society: provides the information on the toxic effects of materials necessary for human risk assessment, can be used to rank materials for regulatory purposes on the basis of their acute toxicity, provides advantages for animal welfare by requiring the use of fewer animals than conventional acute oral toxicity tests and by subjecting those animals used to less chance of experiencing pain or distress.

Administration, Oral↗
PubMed1983

Toxicity testing of atracurium.

The toxicity of atracurium has been investigated in subacute tests in rat, dog and monkey, in a fetal toxicity test in the rabbit and in a paranatal study in the cat. No specific adverse effects were found despite administration of supraparalysing doses. It appeared not to cross the placenta at term and the neonatal kitten seemed resistant to its neuromuscular blocking action. In the dog, cat and pig, in which physiological monitoring was undertaken, i.v. injection of three to four times the paralysing dose had little or no effect on arterial pressure or heart rate. The solution did not cause local irritation. Atracurium was not mutagenic in the Ames test.

Animals↗
PubMed1979

Prostacyclin (PGI2) effects on anterior pituitary hormones in the rat in vivo.

Intravenous injection of 600 microgram PGE2 or PGI2 significantly increased serum LH and prolactin levels in estradiol treated ovariectomized rats. There was no effect on serum FSH concentration. PGE2 and PGI2 stimulated LH release in a non-dose dependent manner, while prolactin levels were positively correlated with the dose administered following PGI2 treatment. 6-keto-PGF1 alpha at a comparable dose had no effect on pituitary hormone levels. Subcutaneous administration of 1 mg/kg or 60 mg/kg PGI2 for seven days significantly depressed serum LH level both in male and female rats. These doses had no effect on serum FSH or prolactin levels.

Animals↗
PubMed1978

Echovirus encephalitis and myositis in primary immunoglobulin deficiency.

Two children are described with primary hypogammaglobulinaemia and encephalitis associated with echovirus infection. One also developed a condition resembling dermatomyositis which improved after he was given infusions of plasma containing antibody to the echovirus. Although both died of their encephalitis, the course of the brain disease in one of them may have been prolonged by treatment with specific antibody. These cases, together with another briefly mentioned case in an adult with congenital hypogammaglobulinaemia and echovirus infection, indicate that these patients are particularly susceptible to echoviruses.

Agammaglobulinemia↗
PubMed1976

Neurochemical findings in a perinatal sudanophilic leukodystrophy rich in steryl ester.

Neurochemical and neuropathological studies have been made of a 10-day-old child who suffered from a sudanophilic leukodystrophy. The brain white matter contained abundant sudanophilic material. The patient's grey matter total cholesterol content was 30% higher than whole brain tissue derived from a comparable control. White matter cholesterol content was more than double the control value. Nearly 80% of the white matter cholesterol was esterified. Subcellular fractionation of the white matter resulted in a "floating fraction" rich in cholesteryl ester. The steryl ester fatty acid composition was not typical of control tissue or demyelinating tissue. Patient phospholipid fatty acid composition patterns differed from control, but white matter galactolipid fatty acid composition appeared normal. Cholesteryl ester hydrolase activity appeared normal. Myelin and myelin-like fractions, isolated from diseased and normal brain tissue, were of a primitive developing nature but appeared to be comparable. The findings indicate a neonatal sudanophilic leukodystrophy which doubtless began in prenatal life and which was rich in cholesteryl ester. The aetiology of the leukodystrophy is unknown.

Brain↗
PubMed1975

Neuropathological effects of persistent infection of mice by mouse hepatitis virus.

Mouse hepatitis virus (MHV3) can persist for months in strains of mice with genetically controlled "semisusceptibility" to this virus. The pathology of the chronic neurological disease induced in these animals has been investigated by conventional histology and immunofluorescence. A2G mice develop a chronic choroidoependymitis and meningitis leading to severe hydrocephalus and hydromyelia. In C3H mice a widespread vasculitis was observed, with both viral antigens and bound immunoglobulins in vessal walls. No significant glomerulonephritis was found. Systemic amyloidosis was present in the spleen, liver, and kidneys. The virus was not detected in neural tissues, but brain and spinal cord lesions were found near inflammatory areas surrounding damaged vessels. It is suggested that viral persistance in ependymal cells is directly responsible for the lesions in A2G mice, whereas an immunopathological lesion of blood vessels of the central nervous system underlines the damage to mice of the C3H strain.

Animals↗