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Biomedical subjects

A Werner

Publications and source records attributed to A Werner.

At least 199 records · Page 11Linked to original sources
PubMed1991

Transvaginal intratubal embryo transfer: a new treatment of male infertility.

Intratubal embryo transfer is a new method in the treatment of human infertility. Following transvaginal sonographic oocyte retrieval, in-vitro fertilization (IVF) is performed and embryos are transferred into the Fallopian tube transvaginally. In comparison with gamete intra-Fallopian transfer (GIFT), fertilization under in vitro conditions offers the advantage that the success of the fertilization process can be examined. Therefore, this method can give important diagnostic information, especially in cases of poor sperm quality or unexplained infertility. After fertilization in vitro and transfer into the tube, embryonic development occurs in the physiological milieu of the oviduct. Transvaginal intratubal embryo transfer was performed in 95 patients with male factor infertility. In 29 cases (31%), a pregnancy was achieved. One abortion, but no ectopic pregnancy was observed. This method combines the advantages of IVF and GIFT and offers a successful procedure for the treatment of infertility.

Embryo Transfer↗
PubMed1991

Cellular mechanisms in proximal tubular reabsorption of inorganic phosphate.

Filtered inorganic phosphate (Pi) is largely reabsorbed in the proximal tubule. Na-Pi cotransport, with a stoichiometry of at least 2:1, mediates uphill transport at the apical membrane; at the basolateral membrane different types of transport systems can be involved in efflux and uptake of Pi from the interstitium. Regulation of transcellular Pi flux involves alteration of the apical Na-Pi cotransport; at least three different cellular control/sensing systems seem to participate in this regulation and are exemplified by parathyroid hormone (PTH)-dependent inhibition, Pi deprivation-dependent increase, and insulin-like growth factor I (IGF-I)-dependent increase in Na-Pi cotransport. For PTH inhibition, recent evidence suggests a role of the phospholipase C/protein kinase C-dependent regulatory cascade in inhibition of Na-Pi cotransport, at least at low PTH concentrations. In addition, an endocytic mechanism seems to be involved in this PTH action. Little is known of the cellular mechanisms in Pi deprivation-dependent and/or IGF-I-dependent increases in Na-Pi cotransport; they are dependent on de novo protein synthesis. Recent experiments involving an expression in Xenopus laevis oocytes led to the identification of an approximately 50 kDa membrane protein that is a good candidate for being involved in brush-border membrane Na-Pi cotransport activity.

Absorption↗
PubMed1991

[Locoregional ascites therapy with cytostatic drugs and immune modulators in gynecologic neoplasms].

35 ovarian cancer patients with ascites have been treated intraperitoneally with mitomycin C or mitoxantrone or interferon beta or tumor necrosis factor (TNF). We observed nor or a little bit ascites in 87.5 per cent after TNF and in 66.5 per cent after mitoxantrone. In addition we applied a systemic monochemotherapy. After mitomycin C or interferon beta only in 40 per cent each an effect could be observed. TNF to day is the most effective substance for treating ascites with moderate toxicity.

Ascites↗
PubMed1990

Aldehyde and nucleotide separations by high-performance liquid chromatography. Application to phenylhydrazine-induced damage of erythrocytes and reticulocytes.

High-performance liquid chromatographic (HPLC) techniques were used for the determination of aldehydes as lipid peroxidation products and of nucleotide concentrations in rabbit red blood cells exposed to phenylhydrazine hydrochloride. Aldehydes were determined by derivatization to dinitrophenylhydrazones, followed by thin-layer chromatographic and HPLC separation with methanol-water on an ODS column. Nucleotides and their derivatives were measured by ion-pair reversed-phase HPLC gradient elution with 10 mM ammonium phosphate buffer containing 2 mM tetrabutylammonium phosphate on ODS columns. The sensitivity of mature erythrocytes was compared with that of reticulocytes against the toxicological effects of phenylhydrazine. For both cell types an increase in aldehyde concentrations, especially of 4-hydroxynonenal, and a decline in both energy-rich nucleoside triphosphate and NAD+ were demonstrated.

Aldehydes↗
PubMed1990

Demonstration of cross-reactive antibodies able to elicit lysis of both HIV-1- and HIV-2-infected cells.

A total of 100% of sera from a large number of HIV-1-infected patients contained antibodies able to elicit Antibody-dependent cellular cytotoxicity lysis of cells infected with the HIV-1 isolates IIIB or RF. Levels of activity could not be correlated with activities in ELISA or neutralizing antibody assays nor with the clinical status of the patients. Surprisingly, 8 of 156 patients sera could additionally elicit lysis of HIV-2-infected cells, and cold target competition assays demonstrated that the cross-reactivity was apparently mediated via recognition of common epitope(s) expressed on the surface of cells infected with either group of HIV. The ADCC mechanism was shown to be mediated by a CD16+ lymphocyte. This demonstration of an effector mechanism able to attack and eliminate cells infected with a wide range of HIV strains has obvious implications for development of putative vaccines.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1990

Expression of rat liver Na+/L-alanine co-transport in Xenopus laevis oocytes. Effect of glucagon in vivo.

Poly(A)+ RNA (mRNA) isolated from rat liver was injected into Xenopus laevis oocytes, and expression of Na+/L-alanine transport was assayed by measuring Na(+)-dependent uptake of L-[3H]alanine. Expression of Na+/L-alanine transport was detected 3-7 days after mRNA injection, and was due to an increment of the Na(+)-dependent component. After injection of 40 ng of total mRNA, Na(+)-dependent uptake of L-alanine was 2.5-fold higher than in water-injected oocytes. In contrast with Na+/L-alanine transport by water-injected oocytes, expressed Na+/L-alanine transport was inhibited by N-methylaminoisobutyric acid, was inhibited by an extracellular pH of 6.5 and was saturated at approx. 1 mM-L-alanine. After sucrose-density-gradient fractionation, highest expression of Na+/L-alanine uptake was observed with mRNA of 1.9-2.5 kb in length. Compared with mRNA isolated from control rats, mRNA isolated from glucagon-treated rats showed a approx. 2-fold higher expression of Na+/L-alanine transport. The results demonstrate that both liver Na+/L-alanine transport systems (A and ASC) can be expressed in X. laevis oocytes. Furthermore, the data obtained with mRNA isolated from glucagon-treated rats suggest that glucagon regulates liver Na+/L-alanine transport (at least in part) via the availability of the corresponding mRNA.

Alanine↗
PubMed1990

Expression of renal transport systems for inorganic phosphate and sulfate in Xenopus laevis oocytes.

As a first step within an experimental strategy (expression cloning) leading to the structural identification of the two brush-border membrane transport systems for phosphate and sulfate, we have studied the expression of Na(+)-dependent uptake of phosphate and sulfate in Xenopus laevis oocytes injected with rabbit kidney cortex poly(A)+ RNA (mRNA). Na(+)-dependent uptake of phosphate and sulfate was stimulated in a dose- and time-dependent manner up to 20-fold as compared to water-injected controls. After fractionation of the mRNA on a sucrose gradient (or by preparative gel electrophoresis), two neighboring fractions were identified to stimulate Na(+)-dependent phosphate uptake (average size: 3.4 kilobases) and Na(+)-dependent sulfate uptake (average size: 3.7 kilobases). The two transport systems can be discriminated by their inhibition by thiosulfate, which reduced sulfate uptake, but not phosphate uptake. Kinetic characterization of the expressed Na(+)-dependent transport activities results in properties similar to those described for transport activity in renal brush-border membrane vesicles.

Animals↗
PubMed1990

Interrelation between nucleotide degradation and aldehyde formation in red blood cells. Influence of xanthine oxidase on metabolism: an application of nucleotide and aldehyde analyses by high-performance liquid chromatography.

The mechanism by which hypoxia leads to irreversible cellular damage is poorly understood. A decrease in purine nucleotides is common to all ischaemic tissues, yielding hypoxanthine as the substrate of the xanthine oxidase reaction. Excessive production of radicals via xanthine oxidase induces peroxidation of unsaturated fatty acids, accompanied with the formation of aldehydes. The nucleotides and aldehydes were determined by high-performance liquid chromatography (HPLC) of red blood cell extracts. Nucleotides and their derivatives were determined by HPLC on an ODS column and elution with 10 mM phosphate buffer containing 2 mM tert.-butylammonium phosphate. The aldehyde production in glucose deprived red blood cells was stimulated by addition of xanthine oxidase and by inhibition of different haemotype enzymes with sodium azide. Aldehydes were analysed by derivatization to dinitrophenylhydrazones, followed by thin-layer chromatographic and HPLC separation with aqueous methanol on an ODS column. The HPLC methods presented are appropriate for the determination of nucleotides, nucleosides and nucleobases, in addition to alkenals and hydroxyalkenals in extracts of oxidatively stressed red blood cells.

Aldehydes↗
PubMed1990

Expression of rat liver canalicular sulfate carrier in Xenopus laevis oocytes.

Poly(A)+ RNA (mRNA)extracted from rat liver was injected into Xenopus laevis oocytes and the expression of sulfate transport was determined by measuring [35S] sulfate uptake. Compared to water-injected oocytes, which exhibited virtually no sulfate uptake, injection of rat liver mRNA resulted in a time- and dose-dependent increase in uptake of sulfate. Depending on the method used for the isolation of the mRNA, sulfate uptake was stimulated after injection (40 ng after 6 days) between 8- and 72-fold compared to water-injected oocytes. Sulfate uptake of oocytes injected with mRNA was found to be sensitive to 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (IC50 less than 20 microM) and could also be inhibited by thiosulfate. Sulfate uptake of injected oocytes showed Michaelis-Menten kinetics (apparent Km, 0.31 mM) which is similar to the Km of the sulfate/bicarbonate antiporter of rat liver canalicular plasma membranes. After fractionation by a sucrose density gradient, the mRNA encoding for the expressed rat liver sulfate carrier was found in fractions containing messages of 3.5-4.0 kilobases in length.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1990

Annealing as a mechanism of increasing wear resistance of composites.

The objective of this study was to examine the influence of a short-term exposure to heat (125 degrees C) on the wear resistance of composites. Both light- and chemically initiated materials improved by 20-60%. However, the improvement was also attained in the course of time if the materials had not been exposed to heat. The heat-induced improvement could not be explained by a continuation of polymerization but rather by stress relief, which is common for annealing processes. Polymerization shrinkage stresses, initially concentrated mainly around the filler particles, became more homogeneously distributed by the heat treatment. The long-term improvement of the non-heat-treated materials was based on the same mechanism, but proceeded more gradually.

Composite Resins↗
PubMed1990

Discrimination between antibodies to HIV-1 and HIV-2 in sera from northern Zaire.

136 selected sera from Northern Zaire were screened for antibodies against HIV-1 and HIV-2 using the ELISA method. Reactive sera were confirmed with commercially available Western Blots and additional tests. A data base was used for evaluation of the results. The sera were collected in the town Isiro and in remote rural areas. 36 sera were reactive in the HIV-1 ELISA (ELAVIA-1), 19 of them were confirmed in the HIV-1 Western Blot (Biorad). 21 sera were reactive in the HIV-2 ELISA, but they were not confirmed as HIV-2-specific in three HIV-2 Western Blots (Diagnostics Pasteur, Biorad, Paul-Ehrlich-Institut).

Blotting, Western↗
PubMed1990

Comparative HPLC Analyses of Alkamides within the Achillea millefolium Group.

Petrol/Et (2)O extractable alkamides from the subterranean parts of different members of the ACHILLEA MILLEFOLIUM group were separated and compared by reversed phase HPLC. Apart from different retention times, each peak could be characterized by its typical UV spectrum obtained by on-line photodiode array detection. Based on previously isolated and identified alkamides, a library search program of UV spectra and corresponding retention times was prepared which greatly facilitated a general comparison of the different HPLC profiles. Apart from the dominating deca-2 E,4 E,6Z-trienoic piperideide in the European representatives ( A. MILLEFOLIUM, A. PANNONICA, A. COLLINA, A. ASPLENIIFOLIA, A. SETACEA), the different cytotypes may be characterized by various accumulation tendencies, mainly towards two isomeric decatetraenoic piperideides and (+)-sesamin. The amide patterns of the Asian and North American members ( A. ASIATICA, A. LANULOSA) clearly deviate; the characteristic decatrienoic and decatetraenoic piperideides are replaced here by a preponderance of decadienoic acid-derived isobutylamide and piperideide. Since there are no diploid members known from North America, the striking chemical similarities with the diploid Asian members strongly suggest an Asian origin.

Journal Article↗
PubMed1990

[Chemosensitivity studies with soft agar culture systems in ovarian cancer].

Since 1982, chemosensitivity studies have been conducted in our laboratory with 181 tumour samples from 132 woman patients suffering from carcinoma of the ovaries, using the colony test and capillary assays. Colonisation rates were 67% and assay rates between 60 and 47%; in 36 cases the in vitro result was compared with the course of the disease observed in vivo. Whereas in 11 of 12 patients it was possible to correctly assess chemoresistance (in vitro growth inhibition less than or equal to 49%) pretherapeutically, chemosensitivity (growth inhibition greater than or equal to 50%) proved more difficult to confirm, 15 predictions being true and 9 false. To assess the prognostic significance of the test results, survival curves were calculated from the data of 33 patients. With a p-value of 0.49, the courses of disease of "in vitro resistant" and "in vitro sensitive" patients differed only slightly from one another. We can conclude from our experiments, that an important indication for performing the colony test in ovarian carcinoma should always be assumed in patients with a poor prognosis, e.g. in women having a large postoperative residual tumour. If, in such cases, the possibility of chemosensitivity testing via the colony test is considered, this examination may offer the chance of sparing the patient additional strain due to the side effects of a treatment with cytostatics if the latter is most likely to be of no significant use.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Productive infection of both CD4+ and CD4- human cell lines with HIV-1, HIV-2 and SIVagm.

Human monolayer cells of various origins were shown to be susceptible to infection by HIV-1, HIV-2 and simian immunodeficiency virus obtained from African green monkeys (SIVagm). Immunoperoxidase staining revealed infection of 2-7% of the monolayer cells, although in order to achieve infection approximately 50-fold more virus was necessary than with CD4(+)-permissive lymphoma cells. No CD4-receptor antigen expression by fibroblastoid cells was detectable by immunofluorescence using several monoclonal antibodies (MAbs), although a low level of CD4-specific messenger RNA expression was revealed by Northern analysis (with the exception of Tera-1 and RD cells). Attempts to block viral infection by anti-CD4 MAbs indicated a CD4 receptor-mediated mechanism for all lines tested except RD cells. We conclude that a low level of CD4-receptor expression is sufficient to allow infection of fibroblastoid cells. The infectability of a CD4-negative cell line indicates a second pathway of cellular infection, possibly mediated by a cellular receptor distinct from the CD4 molecule.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Soluble CD4 enhances simian immunodeficiency virus SIVagm infection.

The CD4 molecule is expressed on T-helper cells and serves as the cellular receptor for the human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2) and for the simian immunodeficiency viruses SIVmac and SIVagm. HIV-1, HIV-2, and SIVmac infectivity can be blocked by monoclonal antibodies (MAbs) directed against the CD4 molecule and by soluble CD4 proteins (sCD4). In the present study, we demonstrated not only lack of inhibition, but 10- to 100-fold sCD4-dependent enhancement of SIVagm infectivity of human T-cell lymphoma lines, although SIVagm infection was blocked by MAbs OKT4a and Leu3a. SIVagm enhancement with sCD4 was suppressed by MAbs OKT4a and Leu3a to levels observed without addition of sCD4. The infectivity of all four tested SIVagm variants was enhanced by sCD4 on all tested lymphoma cell lines. These results suggest a second step (second or secondary receptor) required for enhancing virus entry into the cell and may have serious implications for approaches to the treatment of acquired immunodeficiency syndrome on the basis of modified sCD4 molecules.

Animals↗