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Biomedical subjects

D A Bosch

Publications and source records attributed to D A Bosch.

81 records · Page 5Linked to original sources
PubMed1980

Indications for stereotactic biopsy in brain tumours.

The techniques of stereotactic biopsy of mass lesions of the brain are described, and the indications are discussed. Since computerized axial tomography has become available the decision to perform a stereotactic biopsy is made more frequently than previously. Stereotactic techniques for neuro-oncology are a continously expanding field of largely diagnostic and sometimes therapeutic prodecures. It now seems likely that most centres concerned with brain tumour patients will make use of stereotactic biopsies in the future. A series of 60 stereotactic biopsies performed in the management of otherwise inaccessible tumours of the brain is presented.

Biopsy↗
PubMed1978

Treatment of colloid cysts of the third ventricle by stereotactic aspiration.

Four patients are described with a colloid cyst in the anterior part of the third ventricle, causing obstruction of the foramina of Monro. Stereotactic aspiration of the cyst was performed after exact neuroradiological localization, including CT scan. The great advantages of the technique presented are discussed.

Adult↗
PubMed1977

Short and long term effects of methyl- and ethylnitrosourea (MNU & ENU) on the developing nervous system of the rat. I. Long term effects: the induction of (multiple) gliomas.

Single injections on ENU to WAG-rats were given in the perinatal period and repeated injections of MNU to adult WAG-rats. In the tables illustrating the various experiments, the occurrence of tumors is given for each animal; the tumors are classified according to their sites. For the brain tumors a subdivision is made between those macroscopically visible and those discovered only under microscopy. It is noteworthy that the ratio between neural and extraneural tumors in the perinatally exposed animals is rather constant (about 90 and 10 per cent, respectively). In the experiments on young adult rats neural tumors still predominate, but estraneural ones rise to about 40 per cent. The incidence of neural tumors is impressively high in perinatal induction experiments (greater than 95 per cent). Almost all CNS tumors showed the characteristics of oligodendrogliomas; highly differentiated in the smaller tumors and more anaplastic with regressive changes in the larger ones.

Age Factors↗
PubMed1977

Short and long term effects of methyl- and ethylnitrosourea (MNU & ENU) on the developing nervous system of the rat. II. Short term effects: concluding remarks on chemical neuro-oncogenesis.

The cytotoxic action of various single doses of MNU and ENU on developing neural and extraneural tissues was studied at different stages of development. Examination revealed lethal damage. (L.I.) and mitotic inhibition (M.I.), confined to proliferating cells only, and caused by the number of alkyl groups administered. In studying the duration of M.I. a difference was found in duration of the cell cycle arrest after MNU or ENU. The arrest lasted longer for MNU than for ENU, and the neural tissues turned out to be more sensitive than the extraneural ones. Moreover, among the reappearing mitotic figures abnormal ones were noticed frequently. After pulse-labeling with thymidine this arrest could be traced to take place in or before entering the S-phase. During the period of this arrest a low, but specific, activity was found that might point to the existence of repair-processes in vivo. Finally, we directly demonstrated alkylations in tissue-sections by the use of (14C-methyl)-MNU. High radioactivity was found with a random distribution over the various tissues, cell types and even cellular compartments. Therefore--in contrast with the cytotoxic effects--alkylation seems to occur in all cell types. In conclusion, it seems justified to consider the matrices of proliferating cells in the central nervous system as the target tissue-areas for the carcinogenic action of both MNU and ENU. Re-entrance of these damaged cells into their cycle prior to the elimination of altered bases from DNA might be of great importance for the problem of oncogenesis.

Age Factors↗
PubMed1976

Temporary cell cycle arrest in neural and extraneural developing rat tissues after exposure to methyl--and ethylnitrosourea.

8 days old rats were exposed to 20 or 100 mg/kg b.w. of either Methylnitrosourea (MNU) or Ethylnitrosourea (ENU), followed by injection of 10 muCi/g b.w. of (3H-methyl)-Thymidine. After a 100 mg dose of MNU or ENU in both neural and extraneural tissues a total inhibition of S-phase radioactivity is observed that lasts longer for MNU than for ENU. Moreover reappearance of S-phase cells in the neural tissues is later (36-48 h) than in the extraneural tissues (24-36 h) for both drugs. In both neural and extraneural tissues reappearance of S-phase cells is consistently found to occur about 12 h earlier than recurrence of M-phase cells. After a 20 mg dose of MNU or ENU in both neural and extraneural tissues a clear decrease in S-phase radioactivity is found after a 6 h' interval only. There are only slight differences between the various tissues and drugs. In developing rat tissues there is obviously a trend for both mitotic activity and S-phase radioactivity to decrease with increasing single doses of MNU or ENU. Our results point to an arrest in or before entering the S-phase of the cells involved. The more pronounced cytotoxic activity of MNU as compared to ENU is discussed. Recurrence of DNA synthesis and re-entrance of damaged cells into their cycle prior to the elimination of altered bases from DNA might be of importance for the problem of oncogenesis.

Animals↗