Search

The cell proliferation in the atherosclerotic plaques of cholesterol-fed rabbits has been morphologically studied by using colchicine and [ 3 H]thymidine. Colchicine blocked mitoses and tritium labeled nuclei were particularly numerous in early plaques as well as in the smooth muscle cells of the underlying media; they were mainly located in the most superficial parts of the intimal thickening beneath the endothelial layer. Less numerous tritium labeled nuclei and colchicine metaphases were found in more advanced, fibro-fatty and fibrous plaques. After withdrawal of cholesterol feeding, proliferative changes were still present, but far less evident. From these findings it appears that the initiation and the evolution of the atherosclerotic plaque are closely associated to a proliferative reaction of the arterial wall involving both the medial smooth muscle cells and the cellular constituents of the intimal lesion.

Swiss mice were intranasally infected with influenza A2 virus and treated with urethan in order to detect whether the joint action of the two agents would enhance the development of lung tumors. The average number per mouse of the typical lesions induced by the two treatments together with their location, their histological and histochemical characteristics and the percentage of death in the different groups of animals were recorded. Results indicated that 51.7 % of the mice infected with influenza virus and treated with urethan had both bronchial dysplastic lesions due to influenza virus, and tumors induced by urethan. In this group the number of tumors was smaller than in the mice treated with the carcinogen only and no invasive pulmonary carcinomas were observed. The dysplastic lesions caused by influenza A2 virus as well as the lung adenomas induced by urethan maintained their typical histological and histochemical characteristics even when occurring in a close position. The failure of urethan to enhance the induction of lung tumors in mice exposed to influenzal infection might be ascribed to the different primary sites of response of the pulmonary tissue to the two agents, i.e. the bronchial epithelium for influenza virus and the alveolar epithelium for urethan.

The helix-to-coil transition in dichloroethane–dichloroacetic acid (DCE–DCA) mixtures for poly-N-δ-carbobenzoxy-L-ornithine (PCBO) and for poly-N-γ-carbobenzoxy-Lα,γ-aminobutyric acid (PCBBA) have been studied by ORD and the “heat of solution” method. The results provide strong evidence for the existence of a very specific side-chain/side-chain interaction in PCBBA, which is discussed on the basis of a detailed structural model. The main sources of enthalpy and entropy changes in helix-coil transitions of uncharged homopolypeptides in DCE–DCA mixtures are also discussed briefly.

Some data of the literature point out that a growth hormone lack, due to hypophysectomy, can interfere on the onset and development of carcinogen induced and transplantable tumours. The data regarding the experiments on pituitary dwarf mice, in which 20 methylcholantrene induced epithelioma develop in a lower percentage than normal animals, seem particularly interesting. The present investigation was carried out on 24 dwarf mice and on their phenotipically normal litter mates, by transplanting the Ehrlich ascites tumour and sarcoma 180 both in solid or ascitic form. Body weight increase at the 8th and 15th day from tumour transplantation, survival time, and weight, morphological and histological features of tumours have been considered. The results show that the take and growth of tumours behave in quite similar manner both in dwarfs and in normal controls. The conclusion is then reached that for the studied tumours no growth hormone dependance exists. The differences in hormone dependance between transplantable tumours and the ones induced by chemical carcinogens are briefly discussed.

The antitumour activity of some pyrimidine thio-derivatives has been studied simultaneously with their chronic toxic action. 2-thiocytosine (showing a rapid and nearly total urinary elimination), subcutaneously injected to rats in dose of 100 mg/kg for 39 times consecutively, induces only a slight reduction of erythrocytes and leukocytes in the circulating blood, with relative lymphocytopenia and moderate increase in leukocyte fragility, whereas the values of basal metabolism and weight curve are unmodified. From a morphological standpoint, the only valuable data are a slight stimulus towards neutrophils maturation and a similarly slight lymphoid hyperplasia in the lymph nodes. 2-thio-5-methylcytosine, subcutaneously injected at the same dose for 11 times consecutively, causes a remarkable mortality rate and inhibition of the body growth. Furthermore, differential blood count inversion, increased fragility of withe blood cells and inhibition of the first stages of erythropoiesis with stimulus towards neutrophils maturation are observed. The morphological changes are mainly characterized by nuclear degenerations of the reticuloendothelial system, which are particularly manifest in the spleen and may lead to cell death and, consequently, to reduction of the cellular density. As concerns the urinary elimination, in this case the 22 per cent only of the administered dose is recovered in urines. The changes induced by both the experimented pyrimidine derivatives, and especially by 2-thio-5-methylcytosine, are compared with those referred to in the literature concerning antimetabolic products.

Histological methods show that low doses of (±)-isoprenaline may produce cardiac necroses in the rat. The percentage of animals with focal necroses was related to the dose within the range 0·005 to 0·5 mg/kg administered subcutaneously. Therefore the heart-damaging effect of isoprenaline as well as the antagonistic effect of β-adrenoreceptor blocking agents could be evaluated quantitatively. Pre-treatment of animals with dichloroisoprenaline, pronethalol and propranolol produced a parallel displacement to the right of the dose-response line for isoprenaline. However, when lesions were already in progress, these agents were without protecting effect.

E stato studiato il quadro enzimatico dei corpi lutei (C.L.) di recente formazione nelle ovaie di ratte ipofisectomizzate. In particolare si e constatato come la comparsa dell'attivita 20α-idrossisteroide deidrogenasica non sia impedita dall'ipofisectomia. Si suggerisce la possibilita che l'ipofisi eserciti una azione inhibitrice sulla comparsa di questo enzima.

Trattando ratte gravide o pseudogravide con ergocornina si puo osservare la comparsa dell'attivita 20α-idrossisteroide-deidrogenasica nei corpi lutei rispettivamente gravidici o pseudogravidici nei quali tale attivita normalmente manca. Perche questo effetto si manifesti sono necessari 2–3 giorni di trattamento. Si constata che l'ergocornina causa la comparsa dell'attivita enzimatica sopra indicata in qualsiasi periodo della pseudogravidanza, e nel periodo della gravidanza precedente l'impianto dell'uovo. L'ergocornina quindi agirebbe tramite l'ipofisi dalla cui regolazione dipende l'attivita 20α-idrossisteroide-deidrogenasica dell'ovaio.

The heat of solution of a series of three polyglutamates as a function of solvent composition was measured. The abrupt increase in heat of solution at the solvent composition of the helix–coil transition (as evidenced by optical rotation data) allows the estimation of the transition enthalpy change. The difference of side chain in the three polyglutamates has no appreciable effect on the transition enthalpy, although it affects the helix stability, as judged from the solvent composition at the transition points. These facts are discussed on the basis of existing models of the transition.