摘要:

The preparation of tritium-labelled vinblastine by the Wilzbach irradiation method is described. Tritiated dihydrovinblastine was concurrently formed and could not be detected or separated from tritiated vinblastine by previously available methods. It is now found that tritiated vinblastine can be freed from the contaminating dihydro compound by chromatography on cellulose phosphate. The rate of urinary excretion of radioactivity by rats given injections of the purified alkaloid has been studied. About 5% of the dose radioactivity is excreted in the urine collected in the 12 hour period after injection; thereafter only very minor amounts of radioactivity are eliminated by this route.

ISSN:0008-4212    

DOI:10.1139/y64-001

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

A single dose of reserpine (1 mg/kg body weight, injected subcutaneously) induced hyperglycaemia which persisted for at least 6 hours in rats kept in slings, but no significant alteration in the level of blood sugar was observed in free-running rats. The administration of a single dose of reserpine to unrestrained rats 3 hours prior to a test dose of insulin (0.5 units/kg body weight intramuscularly) or of tolbutamide (125 mg/kgper os) resulted in a decrease in the sensitivity of the animals to the hypoglycaemic action of these two compounds. Pretreatment with reserpine (1 mg/kg for 2 days) resulted in a failure of a single dose (0.5 mg/kg) of this compound to elevate blood glucose levels, in restrained rats, but such reserpine pretreated animals displayed a decreased hypoglycaemic response to a test dose of insulin.The hyperglycaemia observed in restrained rats following the injection of a single dose of reserpine was still observed in animals from which the pancreas had been completely removed, indicating that the change in blood glucose level in response to reserpine in these animals was not dependent on the presence of a pancreatic factor.

ISSN:0008-4212    

DOI:10.1139/y64-002

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

The influence of perfusion pressure on ventricular fibrillation was studied in the isolated rabbit heart. Sudden drops in perfusion pressure inhibit ventricular fibrillation in a few minutes, whereas a slow decrease of the pressure does not stop the fibrillation, but nevertheless reduces the ventricular firing rate. High perfusion pressures facilitate the induction of fibrillation; low pressures delay the production of arrhythmias and shorten their duration. It is postulated that this effect of pressure is primarily mechanical and not strictly dependent upon changes in the coronary flow or in the myocardial temperature.

ISSN:0008-4212    

DOI:10.1139/y64-003

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Total sialic acid content of rat livers and tumors was determined by acid hydrolysis of tissue samples, isolation on Dowex-2 columns, and reaction with thiobarbituric acid. Normal rat liver was found to contain 465 μg of neuraminic acid per g of fresh tissue. In rats bearing hepatomata induced by the feeding ofp-dimethylaminoazobenzene, the tumors contained an average of 1162 μg/g, while the surrounding liver contained 587 μg/g. Treatment of tissue sections with purified neuraminidase liberated only 27–28% of the sialic acid from liver tissue, but 49% of that in the hepatomata. Paper chromatographic analysis indicated a difference between normal liver and hepatomata with respect to the types of sialic acid present.

ISSN:0008-4212    

DOI:10.1139/y64-004

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

The serotonin, noradrenaline, and monoamine oxidase (MAO) levels in the brain, liver, lung, and kidney of rats treated with phenelzine (β-phenylethylhydrazine) were compared with the levels in the same tissues in untreated rats. The administration of the drug was found to markedly reduce the MAO activity in all tissues in 3 hours. Recovery to a supranormal level occurred in the liver in 72 hours. Kidney MAO activity returned to normal in 36 hours, while brain and lung MAO had not recovered in 72 hours. The serotonin level in the brain, liver, and kidney increased as the enzyme level decreased. No change occurred in the serotonin concentration in the lung. The noradrenaline level in the brain was not altered by the drug, whereas a decrease was noted in the lung and both kidney and liver showed an increase at 3 and 36 hours. It is postulated that the central action of MAO-inhibiting agents is mediated through serotonin. The increase in liver noradrenaline suggests that MAO must play some role in the metabolism of the amine. Since the concentration of serotonin in the lung was not changed when the enzyme was inhibited, it is conceivable that lung tissue may serve as a storage site for serotonin.

ISSN:0008-4212    

DOI:10.1139/y64-005

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Little is known of the cardiovascular effects of endrin insecticide. Experiments to investigate these phenomena were carried out on dogs with a variety of preparations. Results show that acute administration of endrin produces bradycardia, hypertension, copious salivation, hyperexcitability, tonic–cionic convulsions, increased body temperature, leukocytosis, hemoconcentration, and decreased blood pH. Cerebral venous pressure and cerebrospinal fluid pressure elevations are also prominent features of endrin poisoning. Although most of these effects appear to be caused by endrin acting directly on the central nervous system some may result secondarily from altered cerebral hemodynamics.

ISSN:0008-4212    

DOI:10.1139/y64-006

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Isolated human and dog iliac arteries were mounted in a double-chambered plethysmograph and perfused with merthiolate solution. Various degrees of stenosis were produced by plastic rings. Only arteries with moderate stenoses (i.e. those that produced a distal thrill and bruit) developed poststenotic dilatation, but all of them did. The dilatation usually started within 5 minutes, progressed rapidly for 20 to 30 minutes, and then more slowly for up to 3 days. Pressure–volume measurements showed that the dilated segment was more distensible than normal.

ISSN:0008-4212    

DOI:10.1139/y64-007

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

After hypophysectomy the pancreas was reduced in weight and its amylolytic activity decreased. This activity was restored partially by the administration of ACTH or by cortisone, but desoxycorticosterone was without significant effect. When both ACTH and desiccated thyroid were given together, complete restoration of pancreas weight per unit of body weight was achieved but amylolytic activity, though significantly increased over the levels found in the hypophysectomized animals, was still below that found in intact pair-fed controls. It appears that part of the pituitary influence in maintaining the exocrine pancreas is mediated through the adrenal cortex and that the 11-oxygenated steroids are involved in this effect.

ISSN:0008-4212    

DOI:10.1139/y64-008

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

The influence of synthetic oxytocin and synthetic lysine-8-vasopressin on the release of thyrotrophin (TSH) from slices of the "basophilic" zone of bovine anterior pituitary glands was determined. Up to 10-fold stimulation of TSH release occurred in the presence of the peptide hormones at low concentrations (approximately 10−11to 10−9 M). Concentrations greater than 10−9 Mwere less stimulatory, ineffective, or inhibitory. In general, vasopressin stimulated at lower concentrations than did oxytocin. The dose–response curve of oxytocin began to descend at lower concentrations than did that of vasopressin.Stimulation of I131discharge from the thyroids of propylthiouracil (PTU)-treated, day-old chicks was produced by the intraperitoneal injection of as little as 4 ng vasopressin or 25 ng oxytocin. As the injected dose of either peptide was increased beyond an optimal level, there was less enhancement of I131discharge, and, with further increases, inhibition. The decreasing response began with lower doses of oxytocin than of vasopressin. The similarities of the dose–response curves of thyroid I131discharge and of in vitro release of TSH indicate that the in vivo effects of injected neurohypophysial peptides are mediated through the release of endogenous TSH.

ISSN:0008-4212    

DOI:10.1139/y64-009

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Two groups of female hamsters (150 ± 50 g) were subjected to decompression from various pressures above atmospheric to a final pressure of 1 atmosphere. In one of these groups the wet:dry lung weight ratio was determined. Elevation of this ratio was taken as evidence of lung oedema. In the other group a postmortem test for valvular rupture of the lungs was applied. This test is based on the principle that air passing from a ruptured lung into the intrapleural space cannot reenter the lung, owing to valvular action of the lung tissue at the site of rupture. The results suggest that two modes of death may result from decompression: rapid death associated with tension pneumothorax, and relatively slow death associated with lung oedema. The relative incidence of tension pneumothorax, as compared to lung oedema, increases with increasing severity of decompression.

ISSN:0008-4212    

DOI:10.1139/y64-010

出版商:NRC Research Press    

年代:1964

数据来源: NRC