Biomedical subjects

J E Castro

Publications and source records attributed to J E Castro.

112 records · Page 7Linked to original sources

PubMedDate not supplied

Distribution of 3H-thymidine-labelled C. parvum in mice.

Little is known of the localisation of injected Corynebacterium parvum. We therefore developed a method of radiolabelling this vaccine and determined its distribution in the mouse. Live C. parvum (Wellcome, strain CN 6134) was grown in the presence of 3H-thymidine and subsequently killed by formalin. A high activity, 1-6 x 10(5) cpm/0.1 ml of a 7 mg dry weight/ml concentrated suspension, was obtained. Its biological properties (hepatosplenomegaly and antitumour effects) were similar to those of commercially available vaccine. After intravenous or intraperitoneal injection into normal mice, high activity was recovered in liver and moderate activity in spleen, lungs and small gut. In contrast, after subcutaneous injection, most activity was recorded at the injection site, and little in other tissues. A similar distribution of labelled C. parvum was found in tumour-bearing mice. Only moderate counts were detected in tumour.

Animals↗

PubMedDate not supplied

Effects and mode of action of Corynebacterium parvum on murine tumour metastases.

The effects of Corynebacterium parvum (C. parvum) on Lewis lung tumour metastases have been studied. I.v. and i.p., but not s.c. C. parvum significantly reduced pulmonary metastases. When combined with excision of the primary tumour, C. parvum given not more than 2 days before caused slight reduction of metastases, but when given earlier, it caused significant reduction and some mice were cured. Metastases were increased by silica or cortisone acetate but were unaffected by trypan blue. The antimetastatic action of C. parvum was not altered by these treatments. Thymectomy and irradiation did not affect tumour metastases, or the antimetastatic action of C. parvum, whereas ALS depressed metastasis and abrogated the protective effects of C. parvum. It appears that the inhibitory effects of C. parvum on tumour metastases are mediated through macrophages in concert with a subpopulation of T2 lymphocytes.

Animals↗

PubMedDate not supplied

Effects of surgery and C. parvum on tumour metastases in mice.

Surgical operations depress immune responses. The aim of this study was to observe the effects of operation (amputation) on the growth of the Lewis lung tumour and its metastases and to see if C. parvum counteracted them. Anaesthesia alone, or with amputation, did not affect the growth of the primary tumour but C. parvum depressed it. Anaesthesia did not affect the number of pulmonary metastases but amputation caused significant increase. C. parvum inhibited metastases and completely counteracted the effects of operation. Large amounts of cortisone significantly increased metastases but small doses did not. Experiments in adrenalectomized mice suggested the effects of operation were due to non specific stress.

Adrenalectomy↗

PubMedDate not supplied

Histological changes of intravascular coagulation in mice resulting from intravenous injection of C. parvum.

A histological study was made of liver and other tissues of mice at intervals after injection of C. parvum. As early as 20 min after injection occasional thrombi surrounded by polymorphs were seen in the alveolar capillaries. A general thrombosis rapidly developed in the hepatic vessels with consequent hepatic necrosis. Thrombi also developed in splenic vessels. This intravascular coagulation was prolonged, lasting at least 7 days. There was evidence that fresh thrombi were being formed throughout this time. The thrombosis was mirrored by a fall in platelet counts. The kidney was uninvolved in the reaction. The mechanism of this reaction and its possible relevance to the antitumour action of C. parvum is discussed.

Animals↗