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Biomedical subjects

G Walter

Publications and source records attributed to G Walter.

At least 199 records · Page 11Linked to original sources
PubMed1985

Complexes of polyoma virus medium T antigen and cellular proteins.

Antibodies against synthetic peptides corresponding to the carboxyl-terminal six amino acids, Lys-Arg-Ser-Arg-His-Phe (KF), and an internal region, Glu-Glu-Glu-Glu-Tyr-Met-Pro-Met-Glu (EE), of polyoma virus medium T antigen were used successively to purify medium T antigen by affinity chromatography. Medium T antigen from cell extracts was first bound to anti-KF antibodies and released from the immune complex with excess KF peptide; then it was bound to anti-EE antibodies and released with excess EE peptide. Two proteins, pp60c-src and a new protein of approximately equal to 61,000 Da (61-kDa protein), were copurified because they formed complexes with medium T antigen. The 61-kDa protein-medium T antigen complex was detected in extracts from wild-type-infected and transformed cells but not from cells infected with NG59 virus, which has a mutation in the medium T gene and is transformation defective. Instead, NG59 medium T antigen formed a complex with another cellular protein of approximately equal to 72,000 Da.

Animals↗
PubMed1985

Establishment and characterization of the pluripotent mouse teratocarcinoma cell line TCE.

Embryonal carcinoma cells, the stem cells of teratocarcinomas, are a convenient model system for the study of embryonic development and cell differentiation. We established the pluripotent teratocarcinoma cell line TCE from embryoid bodies of teratocarcinoma strain OTT6050. The feeder independent cell line was characterized with regard to karyotype, differentiation capacities, developmentally regulated gene products, such as alkaline and acid phosphatase, cell surface markers, and by intermediate filament proteins. These parameters are discussed with respect to the developmental potency of the cell line TCE.

Acid Phosphatase↗
PubMed1984

Immunological analysis of v-myc gene products using antibodies against a myc-specific synthetic peptide.

Rabbit antisera were prepared against a synthetic peptide corresponding to the carboxyterminal amino acid sequences of the transforming protein p110gag-myc of avian oncovirus MC29. Analysis of immunoprecipitates formed with these sera (anti-mycC) demonstrated that the gag-myc hybrid proteins encoded by the avian leukemia viruses MC29, CMII, and OK10 were recognized by the anti-peptide sera, but not the gag or pol precursor proteins of helper viruses or the MH2-encoded p100gag-mil protein. In cells transformed by OK10 or MH2, putative v-myc proteins of 60K (OK10) and 59/61K (MH2) were also precipitated by anti-mycC. In addition, the anti-peptide sera reacted specifically with the gag-myc proteins encoded by three partially transformation-defective mutants of MC29, td10A, td10C, and td10H, and by MC29 variant HBI.

Amino Acid Sequence↗
PubMed1984

[Myocardial changes in acute pulmonary artery embolism--an experimental study].

Massive pulmonary embolism usually causes acute right ventricular hypertension. Structural and hemodynamic effects of right ventricular overloading were studied in piglets (weight 17-22,5 kg). Pulmonary arterial obstruction (PAO) was achieved by temporary banding of the main pulmonary artery, the external diameter of the vessel being reduced to one-third (Group I) or by half (Group II) of the original size. In Group I PAO caused a twofold increase of systolic right ventricular pressure (RVP), whereas the systolic left ventricular pressure decreased to 30% of its original value; PAO was terminated after 25 seconds. After PAO, no changes of right or left ventricular function were observed in Group I. Electron microscopy revealed mitochondrial alterations and fragmentations of the sarcomeres. In Group II, PAO was maintained for 60 minutes. Due to PAO, the systolic RVP increased to twice the original value and the systolic aortic pressure decreased by 10%. During the PAO period, a continuous increase of enddiastolic RVP was observed in Group II. After termination of PAO, contractility parameters for the right ventricle were reduced, and right ventricular diameters (RVD) and enddiastolic RVP were increased in comparison to the pre-PAO values. As hemodynamic alterations increased corresponding to the duration of PAO, it is concluded that in case of acute pulmonary embolism early relief of right ventricular overloading may be important.

Acute Disease↗
PubMed1984

Serological characterization of a pluripotent mouse embryonal stem cell line, two transformed derivatives, and an endoderm-like cell line.

The pluripotent mouse embryonal stem cell line BLC 1 and two transformants derived from it by DNA transformation (T1 and T2/K26) as well as the blastocyst-derived cell line BLC 3 were tested for the presence of cell surface antigens recognized by the monoclonal antibodies ECMA-7, anti-SSEA-1 and M 1/22.25, and intermediate filament proteins labeled by the monoclonal antibodies TROMA 1 and TROMA 2 using a three-step indirect immunofluorescence technique. According to present concepts and in agreement with previous data (Wobus et al., 1984a), the results obtained indicate that BLC 1, T1 and T2/K26 are undifferentiated embryonal stem cells, and BLC 3 is an endoderm-like cell line.

Animals↗
PubMed1984

Biogenic grafts in arterial surgery--long-term results (I. The homologous vein--II. The modified heterologous bovine carotid artery--III. The human umbilical vein).

This report summarizes the authors' experience with homologous vein grafts, modified heterologous bovine carotid artery grafts and human umbilical vein grafts in reconstructive vascular surgery. The homologous saphenous vein, taken from living donors, was implanted in 21 patients. The high percentage of early and late complications (28% and 38%, respectively), the difficult availability and the development of modern materials appear to suggest that these grafts, at least the type used in this study, should no longer be employed. The experience with 102 femoro-popliteal and femoro-tibial bypasses in 140 revascularization operations carried out with modified heterologous bovine carotid artery grafts (Solcograft) is presented. The cumulative patency rate was 43% after 5 years for the above-knee and 33% for the below-knee femoro-popliteal bypasses. The high early and late complication rates (37% and 35%) lead us to believe that this graft should also no longer be employed. The human umbilical cord vein (Meadox-Dardik-Biograft) was used in performing 68 femoro-popliteal and 15 femoro-crural bypasses in 60 limbs of 57 patients. The patency rates calculated according to the standard life table method was 36% for the above-knee (after 5 years) and 32% for the below-knee femoro-popliteal bypass (after 4 years) and 31% (after 3 years) for the femoro-tibial bypass, respectively. On the understanding that other materials should be preferred in the individual case, this material still seems to be recommendable as a graft of second or third choice.

Adolescent↗
PubMed1984

DNA-binding activity of simian virus 40 large T antigen correlates with a distinct phosphorylation state.

The state of phosphorylation and the relationship of various subclasses of simian virus 40 large T antigen (large T) differing in DNA-binding activity, degree of oligomerization, age, and subcellular distribution were investigated. Young large T (continuously labeled for 4 h late in infection) comprised about 20% of the total cellular large T. It was phosphorylated to a low degree and existed primarily in a monomeric form, sedimenting at 5S. More than 50% of this fraction bound to simian virus 40 DNA, preferentially to origin-containing sequences. Old large T (continuously labeled for 17 h, followed by a 4-h chase) represented the majority of the population. It was highly phosphorylated and predominantly in an oligomeric form, sedimenting at 15S to 23S. Only 10 to 20% of this fraction bound to simian virus 40 DNA. Another subclass of large T which was extracted from nuclei with 0.5 M salt resembled newly synthesized molecules in all properties tested; it was phosphorylated to a low degree, sedimented at 5S, and bound to viral DNA with high efficiency (greater than 70%). Two-dimensional phosphopeptide analysis of the individual subclasses revealed two distinct phosphorylation patterns, one characteristic for young, monomeric, and DNA-binding large T, the other for old, oligomeric, and non-DNA-binding large T. All sites previously identified in unfractionated large T (K.H. Scheidtmann et al., J. Virol. 44:116-133, 1982) were also phosphorylated in the various subclasses, but to different degrees. Peptide maps of the DNA-binding fraction, the 5S form, and the nuclear high-salt fraction showed two prominent phosphopeptides not previously characterized. Both peptides were derived from the amino-terminal region of large T, presumably involved in origin binding, and probably represent partially phosphorylated intermediates of known phosphopeptides. Our data show that the DNA-binding activity, age, and oligomerization of large T correlate with distinct states of phosphorylation. We propose that differential phosphorylation might play a role in the interaction of large T with DNA.

Animals↗
PubMed1984

Differential phosphorylation of cytoplasmic and nuclear variants of simian virus 40 large T antigen encoded by simian virus 40-adenovirus 7 hybrid viruses.

The phosphorylation patterns of cytoplasmic and nuclear forms of simian virus 40 large T antigen encoded by simian virus 40-adenovirus 7 hybrid viruses were analyzed by two-dimensional peptide mapping. The PARA(cT) mutant which encodes a large T antigen defective for nuclear transport was used as source for cytoplasmic large T antigen. The data suggest that the large T antigen is phosphorylated in a sequential manner at a subset of sites in the cytoplasm and at additional sites in the nucleus.

Adenoviridae↗
PubMed1984

Monoclonal antibodies specific for the carboxy terminus of simian virus 40 large T antigen.

Three mouse hybridomas secreting antibodies against the undecapeptide Lys-Pro-Pro-Thr-Pro-Pro-Pro-Glu-Pro-Glu-Thr, corresponding to the carboxy terminus of simian virus 40 large T antigen, were isolated and cloned. A sensitive enzyme-linked immunosorbent assay was used to characterize the properties of the monoclonal antibodies. All three hybridomas, designated KT1, KT3, and KT4, produced antibodies that immunoprecipitated large T. The antibodies differed in their affinities for the peptide and for the native protein. Antibodies from KT3 precipitated large T better than those from KT1 or KT4. KT3 antibodies also had the highest affinity for the free peptide (5.2 X 10(6) M-1) as determined by radioimmunoassay; KT1 and KT4 antibodies had ca. 5- and 1,000-fold lower affinities, respectively. Inhibition studies with shorter peptides, overlapping the undecapeptide, revealed the approximate regions recognized by the different monoclonal antibodies. KT3 antibodies bound to a region within the carboxy-terminal six amino acids of large T. Antibodies from KT1 and KT4 reacted with sequences located further towards the amino terminus of the undecapeptide. Surprising results were obtained with KT4 antibodies. Their binding to the undecapeptide was completely inhibited by the undecapeptide itself or the carboxy-terminal hexapeptide. The carboxy-terminal pentamer, on the other hand, slightly enhanced binding, and the carboxy-terminal tetramer, Glu-Pro-Glu-Thr, was strongly stimulatory. A model for this effect is proposed. Using the enzyme-linked immunosorbent assay, we confirmed previous studies (W. Deppert and G. Walter, Virology 122:56-70, 1982) which found that antiserum against sodium dodecyl sulfate-denatured large T reacts strongly with the carboxy terminus of large T. By inhibition studies, we identified the approximate region within the undecapeptide recognized by anti-sodium dodecyl sulfate-denatured large T and compared this region with the region identified by antipeptide serum.

Amino Acid Sequence↗
PubMed1984

[Transmission and course of parasitemia of Babesia microti (Hannover I strain) in the bank vole (Clethrionomys glareolus) and field vole (Microtus agrestis)].

In Germany only M. agrestis has been found to be naturally infected with B. microti while in other European countries several rodent species were found as mammalian hosts. In the laboratory C. glareolus got easily infected by German strains of B. microti, if parasitized blood was inoculated. But results of this method are not transferable to natural conditions. Therefore this study was carried out. It was to prove whether C. glareolus is susceptible to B. microti transmitted by nymphs of I. ricinus, or not. To compare the results, M. agrestis was infected in the same way. Both of them proved to be susceptible. The parasitaemia lasted for months. In the beginning the rate of parasitaemia reached 2%, then decreased below 0.1%. The course of infection was variable. In blood smears B. microti could not be detected at all times, so that in field trials the infection rate in mice will often be underestimated. A connection between parasitaemia and gravidity or lactation was not observed under laboratory conditions.

Animals↗
PubMed1984

Prevalence of viral hepatitis among the hospital staff in CSR between 1980 and 1982.

The hepatitis morbidity data were used to study prevalence rate of manifest viral hepatitis among the hospital staff members in CSR over a 3-year period between 1980 and 1982. This study showed that the overall hepatitis morbidity rate was 2.68 per 1,000 health personnel and was 3.6 times as high as that recorded in a normal population matched by age. The mean HBsAg positivity rate was 1.67 per 1,000 and was 5.8 times the rate in the control population group. The rate of HBsAg-negative cases of hepatitis was 1.01 per 1,000 health personnel and was higher than double the rate of morbidity encountered in an age-matched normal population. The highest morbidity rates were recorded in the lower-grade and auxiliary health personnel. When compared with an age-matched normal population the hospital staff members at all departments had distinctly higher morbidity rates than the general population, but the highest risk of acquiring viral hepatitis was evidently run by the personnel at departments of renal dialysis, biochemistry, hematology, infectious diseases, internal medicine, surgery, urology and TRD (tuberculosis and respiratory diseases). Of a total number of recorded cases of viral hepatitis those with HBsAg positivity predominated, especially at departments of urology, TRD, internal medicine, renal dialysis, psychiatry and hematology. Analyzed by specialty and professional status of personnel these viral hepatitis morbidity rates encountered among the hospital staff members seem to point to at least two conclusions: this infection in the health personnel is work-related and its transmission and spread is dependent on the frequency and intensity of contact with the blood and other secretions of infectious patients.

Czechoslovakia↗