Developmental changes in calcium dynamics, protein kinase C distribution and endoplasmic reticulum organization in human preimplantation embryos

Developmental changes in the Ca²⁺ dynamics of human zygotesand preimplantation embryos were related to changes in the distributionof endoplasmic reticulum (ER) and protein kinase C (PKC). Thefertilization-induced Ca²⁺ oscillations were typically observedover >5 h, were ryanodine-sensitive and showed a periphery-to-centrepropagation of Ca²⁺ waves. At the same time, ER and PKC wereaccumulated in the cell periphery. After the appearance of pronuclei,ryanodine-sensitive Ca²⁺ oscillations of lower amplitude andfrequency were observed until the pronuclear breakdown. However,Ca²⁺ waves then began in the perinuclear region, in the areaof ER and PKC accumulation and spread towards the cell periphery.During the second to fourth cell cycle, small sinusoidal Ca²⁺fluctuations were observed; sparse higher-amplitude Ca²⁺ spikes,superimposed on these basal fluctuations, appeared shortly beforecell division. The sinusoidal Ca²⁺ fluctuations were asynchronousin individual blastomeres and disappeared progressively in arrestedembryos. The direction of Ca²⁺ wave propagation and the distributionof ER and PKC were similar to the situation observed in pronuclearzygotes. In contrast to the zygotes, ryanodine did not arrestthe Ca²⁺ oscillations but augmented their amplitude and frequency.These data suggest that human pre-embryos use different mechanismsof Ca²⁺ signalling in the early post-fertilization period, duringthe pronuclear development and during cleavage. calcium dynamics/endoplasmic reticulum/human preimplantation embryos/protein kinase C/ryanodine     

Synthese und charakterisierung von linearem poly(iminoethylen)

Linear poly(iminoethylene) was synthetised by cationic polymerization of 2-methyl-2-oxazoline using BF₃? O(C₂H₅)₂, SnCl₄, and CH₃COBF₄ as initiators and in the presence or absence of CH₃CN. The resulting product, poly(N-acetyliminoethylene), was then hydrolysed in basic medium. The resulting poly(iminoethylene) was identified and characterized by ¹H NMR, ¹³C NMR, X-ray diffraction, and differential scanning calorimetry (DSC). The synthetised polymer will be used as a polymeric support in ionic-exchange resins as well as in macromolecular pesticides.     

F2-isoprostanes stimulate collagen synthesis in activated hepatic stellate cells: a link with liver fibrosis?

Carbon tetrachloride (CCl4)-induced hepatic fibrosis has been considered to be linked to oxidative stress and mediated by aldehydic lipid peroxidation products. In the present study, we investigated whether collagen synthesis is induced by F2-isoprostanes, the most proximal products of lipid peroxidation and known mediators of important biological effects. By contrast with aldehydes, F2-isoprostanes act through receptors able to elicit definite signal transduction pathways. In a rat model of CCl4-induced hepatic fibrosis, plasma F2-isoprostanes were markedly elevated for the entire experimental period; hepatic collagen content also increased. When hepatic stellate cells (HSCs) from normal liver were cultured with F2-isoprostanes in the concentration range found in the in vivo studies (10(-9)-10(-8) M), a striking increase in DNA synthesis (reversed by the thromboxane A2 antagonist SQ 29 548), in cell proliferation and in collagen synthesis was observed. Total collagen content was similarly increased. Moreover, F2-isoprostanes markedly increased the production of transforming growth factor-beta1 by U937 cells, considered a model of liver macrophages. The data provide evidence for the possibility that F2-isoprostanes generated by lipid peroxidation in hepatocytes mediate HSC proliferation and collagen production seen in hepatic fibrosis.     

Etherification of poly(oxymethylene)-diol [α-hydro-ω-hydroxypoly(oxymethylene)] with orthoesters in the presence of Lewis acids

Attempts were made to elucidate experimentally the behaviour of poly(oxymethylene)-diol [α-hydro-ω-hydroxypoly(oxymethylene)] in the etherification reaction in order to explain the decrease of the polymer molecular weight compared with that of the starting product and in order to determine the type of terminal groups and how the thermal resistance and alkali stability can be affected. In fact one finds that, in addition to the wanted terminal ether groups, formyl and orthoformyl (dialkoxymethyl) groups are formed having a different chemical resistance in comparison to that of the pure ethers, particularly in basic media.     

Hypoglycaemic syndromes and antibodies to pancreatic islet cells.

The sera of ten patients with unexplained hypoglycaemia were examined for antibodies to pancreatic islets. Antibodies to pancreatic A, B and D cells (ICAb) were detected in one patient with an associated gastrointestinal tumour.     

Expression of Intercellular Adhesion Molecule-1 (ICAM-1) on Cultured Human Endometrial Stromal Cells and Its Role in the Interaction With Natural Killers

PROBLEM: Recent evidence emphasizes the role of natural killer cells (NKs) as potential effectors of peritoneal immune surveillance directed against the outgrowth of endometrial cells, refluxed with menstrual debris, in ectopic sites. This NK-mediated cytotoxicity toward autologous endometrial antigens seems to be significantly decreased in endometriosis patients. METHOD: We set up experiments to clarify which molecules are involved in NK-endome-trial cell interaction. In particular, we evaluated the surface expression and functional activity of intercellular adhesion molecule-1 (ICAM-1), a cell surface glycoprotein that has been identified as one of the ligands for lymphocyte function-associated antigen-1 (LFA-1), present on almost all leucocyte cell types. Immunofluorescence flow cytometry was used to assess ICAM-1 expression on resting and IL 1β-activated endometrial stromal cells in culture. Dermal fibroblasts were used as control cells. Cytotoxicity and binding assays by ⁵¹Cr release in presence and absence of a specific monoclonal antibody (mAb) against ICAM-1 were then performed in order to determine the effect of this molecule on NK-mediated cytotoxic and binding activity toward endometrial stromal cells. RESULTS: The results of this study indicated that ICAM-1 expression on endometrial stromal cells seems to be constitutively higher than on dermal fibroblasts and can be up-regulated upon exposure to IL 1β. Furthermore, a mAb against ICAM-1 strongly inhibits the binding but not the cytotoxicity of NKs toward endometrial cells. No difference in the expression of this molecule was observed throughout the cycle. CONCLUSIONS: The presence of ICAM-1 on human endometrium might relate to the action of the immunocompetent cells in human specific reproductive events.     

Assessment of ventricular function by radionuclide angiography in patients receiving 4′-epidoxorubicin and mitoxantrone

Summary Serial assessment of ventricular function by means of radionuclide angiography was performed in 50 patients with malignant neoplasms who received either 4-epidoxorubicin or mitoxantrone for longer than 3 months.In 9 of 30 patients give 4-epidoxorubicin, a decrease of 10% in the left ventricular ejection fraction (LVEF) was documented at doses of 143–1200 mg/m². Two patients developed clinical signs of cardiotoxicity at a dose of >1000 mg/m².In 6 of 20 patients given mitoxantrone a decrease of 10% in the LVEF occurred at doses of 26–98 mg/m².This study was supported in part by a grant from the National Cancer Association of South Africa