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Biomedical subjects

R J Collins

Publications and source records attributed to R J Collins.

At least 109 records · Page 6Linked to original sources
PubMed1982

Opiate effects on plasma corticosteroids: relationship to dysphoria and self-administration.

Narcotic analgesics have been shown to raise plasma corticosteroids in the rat. This effect has been interpreted as a response of the rat to the dysphoric properties of the drug. This interpretation is based on the observation that drugs such as nalorphine or cyclazocine which cause dysphoria in man elevate plasma corticosteroids in the rat at relatively low doses. Drugs like morphine or pentazocine which induce little dysphoria in man elevate plasma corticosteroids in the rat only at much larger doses. The corticosteroid-elevating effect is mediated by an opiate receptor since naloxone antagonizes the effect of morphine or the analgesic. U-50,488. Those narcotic analgesics which increased corticosteroid levels at low doses were also found to be poorly self-administered by rats. In contrast, compounds like morphine, pentazocine and the analgesic. U-49,274A, which were self-administered at high rates, elevated corticosteroids only after large doses. The relationship between the dose of a drug which causes elevations in corticosteroid levels and whether or not the drug is self-administered further supports the premise that elevated corticosteroid levels induced by analgesics is due to their dysphoric properties.

Adrenal Cortex Hormones↗
PubMed1982

A ? developmental characteristic of the ultrastructure of childhood leukaemic lymphoblasts.

Areas of chromatin demarcated from the rest of the nucleus ("separations") were found frequently in acute lymphoblastic leukaemias of childhood, in some patients in apparently all leukaemic cells, but rarely in non-lymphocytic leukaemias. In normal lymphocytes, separations were most common in fetal thymus, and less frequent in fetal lymph node and bone marrow, and child thymus, lymph node and marrow. Separations may be a developmental marker, and fetal lymphoid tissues, especially thymus, may have significance in the origin of lymphoblastic leukaemias of childhood. Nuclear loops enclosing cytoplasmic material were associated with, and may have similar significance to, separations.

Bone Marrow Cells↗
PubMed1980

Vagal function in relation to gastro-oesophageal reflux and associated motility changes.

Vagal function in 28 patients with gastro-oesophageal reflux was examined by determining gastric secretory response to insulin-induced hypoglycaemia and pulse-rate variation with respiration. Gastric secretory studies were also performed on 13 patients with duodenal ulcer who had not undergone operations. In all patients the presence and degree of oesophagitis were determined endoscopically and mucosal biopsy and oesophageal manometry were performed. Seven of the 28 patients with gastro-oesophageal reflux showed evidence of impaired vagal efferent function in the upper alimentary tract. No such impairment was found in those patients who showed manometric evidence of oesophageal spasm secondary to gastro-oesophageal reflux. Low pulse-rate variation with respiration was found in 12 of 27 patients with gastro-oesophageal reflux, suggesting dysfunction of cardiac vagal fibres. Impairment of efferent vagal supply may be a causative factor in some patients with gastr-oesophageal reflux but does not seem to be important in oesophageal spasm secondary to gastro-oesophageal reflux.

Adult↗
PubMed1979

Dose and physical dependence as factors in the self-administration of morphine by rats.

Groups of naive rats were offered morphine sulfate for self-admininstration in doses of 0.0032-10 mg/kg for 6 days. On day 7 saline was substituted for morphine. Loss of weight was taken as physiological evidence of dependence. Rats that did not lose weight formed a single population whose mean injection rate did not differ from control rats receiving only saline injections. Injection rates for rats losing weight were log-normally distributed, and the mean of the logarithms of the injection rates was linearly related to the logarithm of the dose. Mean daily injection rates averaged 12 for controls, 23 at 10 mg/kg, and 411 at 0.01 mg/kg. A transient increase in morphine intake after an injection of nalorphine was taken as behavioral evidence of dependence. Nalorphine increased morphine intake when rats were self-injecting 0.32 and 1.0 mg/kg of morphine, but not 0.032 or 0.1 mg/kg. The reinforcing property of morphine may occur without behavioral evidence of dependence.

Animals↗
PubMed1978

Drug labelling.

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Adult↗
PubMed1978

Self-administration of morphine in the rat: relative influence of fixed ratio and time-out.

Rats were offered 3.2 mg/kg of morphine sulfate on a continuous reinforcement schedule until the daily injection rate had stabilized. The effect of fixed ratio schedules of 4 and 8 were compared to imposing time-out periods of 5 and 10 sec immediately followed each injection. The fixed ratio schedules decreased the injection rate while the time-out schedules had no effect. The hypothesis that the effect of a fixed ratio schedule is a consequence of imposing a time-out period, allowing full effects of the injection to be sensed, is not supported.

Animals↗
PubMed1978

Pharmacology of some metabolites of triazolam, alprazolam, and diazepam prepared by a simple, one-step oxidation of benzodiazepines.

A simple, one-step chemical oxidation of triazolam (7) to its 4-hydroxy analogue, 7a, has been developed and applied to other triazolo- and imidazobenzodiazepines. The reaction may be used to convert diazepam to temazepam. 4-Hydroxytriazolo[4,3-a][1,4]benzodiazepines have low central nervous system sedative and anticonvulsant activity in sharp contrast to metabolites of diazepam which remain active. While 10, an alpha-hydroxy metabolite of triazolam, retains much of the activity of 7, 10a, and alpha,4-dihydroxy metabolite of triazolam, is 250 times less potent than 7 on the nicotine-antagonism assay and over 300 times less potent on the traction assay.

Animals↗
PubMed1977

A population of lymphocytes in human blood distinctive in morphology and other characteristics.

Evidence is presented that lymphocytes characterised by being large and having abundant feebly staining, and usually profusely granulated cytoplasm ('pale' cells) are a group which is distinct from the other small basophilic ('dark') cells. In patients with genetic storage disorders characterised by abnormalities of lymphocyte structure, the structural peculiarites were confined to the basophilic cells, and cytochemical differences were found between the 'pale' and 'dark' cells in normal subjects.

Adolescent↗
PubMed1976

Changes in morphine self-administration in rats induced by prostaglandin E1 and naloxone.

Interactions of prostaglandin E1 (PGE1) with morphine have been reported in several test systems and an hypothesis has been advanced for a role of prostaglandins in morphine analgesia and physical dependence. In rats self-administering morphine intravenously, a simultaneous and continuous infusion of naloxone hydrochloride at 56 to 560 mug/kg/day caused the expected increase in injection rate for morphine. Infusion of PGE1 by itself at 56 or 180 mug/kg/day had no effect on the rate of morphine intake. Likewise the addition of PGE1 at 180 mug/kg/day did not potentiate the increase caused by naloxone (56 or 180 mug/kg/day) when it was added to the naloxone infusion. These results do not support a role for prostaglandins in the behavioral aspects of morphine addiction. However, larger doses of PGE1 (1 and 1.8 mg/kg/day), which were without overt effects in normal rats, caused severe and incapacitating prostration in morphinized rats.

Animals↗
PubMed1975

Specificity and sensitivity of skin test reactions to extracts of Toxocara canis and Ascaris suum II. Homologous 48-hour passive cutaneous anaphylaxis tests with sera from infected guinea pigs.

The specificity and sensitivity of adult and larval somatic antigens and perienteric fluid of Toxocara canis and Ascaris suum were investigated by using a modified passive cutaneous anaphylaxis procedure in guinea pigs. Pooled sera from animals infected with low doses (0.01, 0.1, or 1.0 egg/g) were most reactive with the homologous larval antigen preparation. However, the Toxocara antisera were highly reactive with this antigen only, whereas the Ascaris antisera reactions could not be interpreted as being clearly positive with any of the antigen preparations. Sera from hyperinfected animals were also reactive with the homologous larval antigen. In addition, Ascaris larval antigen was reactive with Toxocara antiserum. The reciprocal relationship, i.e., reactivity of Toxocara larval antigen with Ascaris antiserum, was no apparent. In no instance did adult antigens induce reactions that could be interpreted as specific or sensitive indicators of antibody.

Animals↗