Acta histochemica. Supplementband最新文献

Autoradiographic studies have shown that the urothelium of the rat urinary bladder is capable to considerably proliferate in response to a partial cystectomy (one-third resection of the bladder) as is indicated by a 190-fold increase of the 3H-thymidine labelling index above normal levels 45 h postoperatively and an enormous increase of the compartment of proliferating cells (so-called growth fraction). The stimulated urothelial proliferation can be synchronized by multiple, fractionated doses of hydroxyurea (HU), resulting in a high degree of synchrony. Based on these findings, the partial cystectomy model seemed to be a useful tool to examine whether stimulated proliferation exerts a modifying effect on initiation of urothelial carcinogenesis. Following feeding N-butyl-N-(4-hydroxybutyl)-nitrosamine by gavage in 3 fractionated doses during most pronounced proliferation 30, 45 and 70 h postoperatively, the development of bladder tumors proved to be significantly dose- and time-related inhibited. Accordingly, N-methyl-N-nitrosourea (MNU)-induced tumour formation was considerably reduced following intravesicular instillation of the carcinogen at a single dose 45 h postoperatively, when stimulated DNA synthesis reached its peak. Experiments testing a possible cell cycle specific dependence of MNU-initiated tumor development in the partially resected bladder after synchronization of the stimulated proliferation by HU revealed an inhibition of urothelial carcinogenesis in particular, when the carcinogen was administered during the early DNA synthesis phase. The mechanisms underlying the observed inhibition of tumor development in the regeneration urinary bladder are unknown. It is assumed that an increased capacity of the proliferating urothelial cells to repair carcinogen-induced DNA-damage may play an important role.

By means of electron microscopy we have investigated the influence of dilution and cold incubation (0 degree C) on mixed populations of tubulin assemblies consisting of microtubules (MTs) and protofilament ribbons with C- and S-shaped profiles formed in the presence of glycerol. Dilution results in a partial disappearance of ribbons, whereas cold incubation causes a decrease of the percentage of MTs in favour of C-ribbons, probably produced by splitting of MT ends. In the case of dilution, we assume a lower dynamic stability of ribbons compared with MTs, which was already observed during long-time incubation of mixed population (Böhm et al., Biochem. Biophys. Acta 929, 154, 1987), whereas the splitting effect in the cold should be caused by the deficiency of MT-bound microtubule-associated proteins (MAPs), which is observed in the presence of glycerol.

The quality of X-ray microanalytical results in biology and medicine depends primarily on the preparation techniques used. Modern preparative methods for the X-ray microanalysis of both nondiffusible and diffusible elements are reviewed. It is demonstrated that native results can be obtained if a few conditions in the preparation are fulfilled. Technical requirements for the preparation are shown to be comparable to or even less restrictive than those needed in conventional electron microscopy.

The present most useful markers for breast appear to be: a. Actin, myosin and cytokeratins for distinguishing benign (mixed) from malignant (single cell) proliferations. b. Psychological assessment for prediction of long term cancer survival (Pettingale, 1985). c. Helix pomatia lectin binding for distinguishing cancers that have metastasized from those that have not. This is so far limited to 3 independent retrospective studies (Leathem, 1987; Fenlon, 1987; Fukutomi, 1989) and now needs prospective confirmation.

The increasing application of transvascular endomyocardial biopsy for diagnostic verification of various heart diseases and elucidation of their etiology relies mainly on light microscopical methods. It is shown by hypertrophic cardiomyopathy as an example that also submicroscopical findings may be of value in diagnostic work, prognosis, and investigating research for etiological relationships. Specific morphological markers for idiopathic HCM were not demonstrable; nevertheless, some characteristic alterations such as fibrillary disorder, excessive folding of nuclear-, intercalated disc-, and sarcolemmal membranes, contraction bands, accumulation of mitochondria, glycogen, and lipid droplets, among others as well as sometimes the thickening of vascular walls with its unknown relations to the so-called "small vessel disease" may be helpful when endomyocardial biopsies are examined with the electron microscope too. Though many cytomorphologic findings are similar to those in dilatative cardiomyopathy, this disease probably is not a final state of HCM. In order to prove the actual cause of both heart failures, more intensive investigating research especially at the molecular biological level is required.