Comparative study on La-promoted Ni/γ-Al2O3 for methane dry reforming - spray drying for enhanced nickel dispersion and strong metal-support interactions.

Dry reforming of methane (DRM) enables an efficient utilization of two abundant greenhouse gases by converting them into syngas, a versatile feedstock for chemical synthesis. Aiming for high catalyst performance and enhanced coke resistance, different preparation techniques of La-promoted Ni/γ-Al2O3 catalysts for DRM were compared facilitating structure-performance correlations. The studied synthesis techniques comprehend incipient wetness impregnation and co-precipitation as well as alternative techniques such as spray drying. All catalysts were fully characterized before and after reaction by N2-physisorption, XRD, H2-TPR and STEM-EDX elemental mapping. Additionally, a thorough investigation of carbon deposits has been carried out by TGA/DSC and STEM-EDX, respectively. The different preparation techniques led generally to very different physical properties, structure, chemical species and anti-coking properties of the catalyst. However, some catalysts with similar physicochemical characteristics differed in catalytic performance and coking resistance. Superior catalytic performance could be reached for catalysts prepared by spray drying and related to excellent Ni dispersion, strong metal-support interaction and very low coke formation of only 2.7% of the catalyst weight. After 6 h time on stream only minor sintering occurred, with few Ni nanoparticles up to 10 nm.

In vitro effects of inhibin on apoptosis and apoptosis related proteins in human ovarian granulosa cells.

OBJECTIVE: To clarify the in vitro effects of inhibin A (I) on apoptotic cell death and its mechanisms in ovarian granulosa cells the immunoexpression patterns of the apoptosis markers caspase-3 and pro- and anti-apoptotic proteins (Bcl-2, Bcl-xl, Bak) were evaluated in ovarian granulosa cells collected from women with different hormonal status. MATERIALS AND METHODS: Granulosa cells were isolated from follicles of women participating in an in vitro fertilization (IVF) program, normally cyclic (NC) and premenopausal women (PrM). The obtained cells were cultured for 72 h with inhibin A (Sigma, USA)--10 ng/ml. The concentration of estradiol in the culture medium was determined by radioimmunoassay using the Coat-A-Count kit (Nippon, Japan), whose intra- and interassay coefficients of variations were 6,8% and 6,2% respectively. The expression of caspase-3, Bak, Bcl-2, Bcl-xl was investigated immunohistochemically. The percentages of immunopositive cells were calculated and Student's t-test was used for statistical analysis. RESULTS: Addition of inhibin A (10 ng/ml) to granulosa cells cultures resulted in increased estradiol production. Maximal stimulation was observed in granulosa cells collected from women participating in IVF whereas minimal effect of inhibin treatment on estradiol production was demonstrated in premenopausal women. Inhibin A exposition enhanced the immunoexpression of prooncogenes (Bcl-2, Bcl-xl) and reduced the expression of caspase-3 and pro-apoptotic protein Bak in ovarian granulosa cells from the three experimental groups. CONCLUSIONS: Our findings suggest that inhibin A in vitro stimulates the estradiol secretion by granulosa cells dependently of the woman hormonal status, while it inhibits apoptotic process in granulosa cells independently of the hormonal status.

Potential role of nitric oxide in endothelin-1 provoked inhibition of progesterone secretion by isolated ovarian granulosa cells.

OBJECTIVE: Nitric oxide (NO) is involved in different cell functions including ovarian steroid production. Endothelin-1 (ET-1) was found to regulate the steroidogenesis in ovarian granulosa cells (GC). The present study was designed to receive more information about the mechanism of action of NO in the process of ET-1 induced progesterone (P) inhibition, using nicotine amide dinucleotide phosphate-diaphorase (NADPH-d) histochemistry as a cofactor of oxidoreductase enzymes (e. g. nitric oxide). METHODS: Granulosa cells were isolated from ovaries of: 1. young women with natural cycle or after in vitro fertilization (IVF), 2. premenopausal women. The obtained cells were cultured with endothelin-1 and the concentration of progesterone in conditioned media was determined by RIA. For the estimation of NADPH-d the histochemical reaction was used. RESULTS: The suppressive effect of ET-1 on P production in granulosa cells was more pronounced in young women with natural cycles, slightly weaker after IVF and the most ineffective in premenopausal patients. The number of NADPH-d positive GCs was higher in young non-hormonally stimulated women, slightly lower after IVF and small in premenopausal ones. CONCLUSIONS: The results indicate the possible role of NADPH-d or NOS in the mechanism of ET-1 provoked P suppression.

A threshold level of gag expression is required for particle formation in rat cells transformed by avian retroviruses.

To test the hypothesis that the block of polyprotein precursor processing and particle formation in RSV-transformed mammalian cells is due to a low level of pr76gag expression, rat tumor cell lines with different amounts of precursor molecules were used. The wild-type forms of pr76gag have been expressed at a high level by use of SV40-based vector and thirty-two stable transfected cell clones were isolated. The gag protein expression was detected in the cell lysate by immunoblotting. Untransfected cells released no proteins that could be detected by immunoprecipitation with anti-RSV serum. Membrane-enclosed gag precursor-polyprotein molecules and infectious virus particles from different stably transfected clones have been found in the medium. Both immature and mature virions of type C morphology were directly detected by transmission electron microscopy. Surprisingly, virus-like particles of morphology similar to mature type C retroviruses were found enclosed within intracellular membranes in a stably transfected nonproducing clone.

[The microcomputer study and processing of the values of the blood pressure and intersystolic interval in laboratory animals]. / Mikrokompiuturno proslediavane i obrabotvane na stoinostite na arterialnoto naliagane i mezhdusistolniia interval na laboratorni zhivotni.

A system is created for study of the agents, affecting the arterial pressure and baroreflectory sensitivity, which comprises:transducer for arterial pressure Statham P23 ID, connected to a polygraph Biomedica O.T.E.; eight-bite analogous-numerical transformer; microcomputer, compatible to Apple 2+; two diskette devices and printer. The arterial pressure of the lab animals (rats, rabbits, cats) is directly measured in a. carotis communis by means of the transducer and is recorded on the polygraph. For the system a computer program is designed which allows archivation of the primary experimental data; automatic and precise determination of the momentary values of the systolic and diastolic arterial pressure and intersystolic interval; determination of the baroreflectory sensitivity by means of linear regressive analyses; printing of the results under the form of diagrams and tables. By means of this system much time is spared, related to the accounting and handling of the experimental data.