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Biomedical subjects

H Körner

Publications and source records attributed to H Körner.

At least 73 records · Page 4Linked to original sources
PubMed1993

An immunodominant CD4+ T cell site on the nucleocapsid protein of murine coronavirus contributes to protection against encephalomyelitis.

The murine coronavirus neurotropic strain JHM (MHV-JHM) nucleocapsid (N) protein induces a strong T-helper cell response in Lewis rats. It has been shown previously that N-specific CD4+ T cells can confer protection against acute disease upon transfer to otherwise lethally infected rats. To define the major antigenic regions that elicit this T cell response, truncated fragments of N protein were expressed from a bacterial expression vector and employed as T cell antigens. Lymphocytes from either MHV-JHM-infected or immunized rats were stimulated in culture with virus antigen, grown and tested for their specificity to the N protein fragments. The carboxy-terminally located C4-N fragment (95 amino acids) induced the most pronounced proliferative response irrespective of whether the lymphocyte culture was derived from immunized or MHV-JHM-infected rats. We established T cell lines specific for the truncated N protein fragments and tested their potential to mediate protection by transfer experiments. Only the T cell line C4-N and the T cell line specific for the full-length N protein were protective. By contrast, all truncated N protein fragments elicited a humoral immune response and contained antigenic sites recognized by antibodies from diseased rats.

Animals↗
PubMed1992

Tumor necrosis factor alpha stimulates expression of adenovirus early region 3 proteins: implications for viral persistence.

Human adenovirus (Ad) can cause persistent infections in humans. Early region 3 (E3) of the virus appears to be implicated in this phenomenon. This transcription unit encodes proteins that interfere in various ways with host cell functions, including (i) cell-surface expression of histocompatibility class I antigens (HLA), (ii) cell-surface expression of the epidermal growth factor receptor (EGF-R), and (iii) the biological activity of tumor necrosis factor alpha (TNF-alpha). We transfected the human cell line 293 with the entire E3 region of Ad2 and investigated the influence of the cytokines TNF-alpha and interferon gamma (IFN-gamma) on cell-surface expression of HLA class I and the EGF-R. Whereas IFN-gamma treatment induced expression of HLA to some extent but not that of the EGF-R, TNF-alpha treatment augmented the reduction of these cell-surface molecules. Subsequent studies on the mechanism of this effect showed a TNF-alpha-dependent upregulation of E3 protein (E3/19K) and mRNA. The significance of this phenomenon was confirmed in infection experiments. A dramatic increase in the amount of E3/19K, even after short induction with low doses of TNF-alpha could be demonstrated. The study provides evidence for an interaction between the immune system and Ad in which the virus takes advantage of an immune mediator to escape immunosurveillance of the host.

Adenoviridae Infections↗
PubMed1992

Genetic amniocentesis in twin pregnancies: results of a multicenter study of 529 cases.

To evaluate the risk of abortion after genetic amniocentesis in twin pregnancies, a retrospective study of 15 centers was performed. The spontaneous abortion rate up to 20 completed weeks of gestation was 2.3%; the abortion rate up to 28 completed weeks, as defined by WHO, was 3.7%. The abortion rate could not be correlated either with the number of needle insertions or with the type of marker dye used. There was also no correlation between the abortion rate and the gestational age at which amniocentesis was performed. A significant association was shown between congenital intestinal obstructions and the application of methylene blue intra-amniotically as a marker dye. Considering the increased natural loss rate in multiple gestations, amniocentesis in twin pregnancies seems to be a safe and reliable technique.

Journal Article↗
PubMed1992

Periplasmic location of nitrous oxide reductase and its apoform in denitrifying Pseudomonas stutzeri.

Immunogold labelling techniques on ultrathin sections of low temperature embedded cells yielded evidence for the periplasmic location of the respiratory enzymes N2O reductase and nitrite reductase (cytochrome cd1) in Pseudomonas stutzeri strain ZoBell. Cell fractionation by spheroplast preparation and two-dimensional electrophoresis showed the absence of a membrane association of these enzymes. Immunocytochemical localization of N2O reductase in a mutant strain deficient in the chromophore of N2O reductase showed the gold label at the cell periphery, indicating that the copper chromophore processing takes place after export of this protein's apoform.

Bacterial Proteins↗
PubMed1992

[Severe hydrops fetalis in a first trimester pregnancy with Ulrich-Turner syndrome].

We report about a case of abundant hydropic evolution of a fetus in the first trimester of gestation. Already in the 8th week of gestation we diagnosed the first references of failure with transvaginal ultrasound. In the following three weeks we observed the progression of the hydrops. The genetic research of fetal tissue after induced abortion show the karyotype 45 X0.

Adult↗
PubMed1992

[Choroid plexus cysts in the 2d trimester--an indication for trisomy 18].

The application of high resolution ultrasound in the prenatal diagnosis enables a detailed differentation of the intracerebral structures in the fetus. In a period of 16 months (Jan. 1990-June 1991) we diagnosed at the "Center for prenatal diagnosis and therapy" at the Charité's Hospital in 14 fetuses among 1800 investigated plexus chorioideus cysts. A rapid karyotyping after cordocentesis was performed in 11 cases. In 3 of them a trisomy 18 could be detected. In one fetus having a normal karyotype we could find besides the cysts multiple structural anomalies. In these 4 cases the termination of pregnancy was performed. In the other 10 pregnancies we could observe a spontaneous regression of the plexus cysts. These results suggest that the prenatal diagnosis of plexus chorioideus cysts is a indication for cytogenetic evaluation in order to detect a trisomy 18.

Abnormalities, Multiple↗
PubMed1992

[Fetal teratoma--diagnosis and management].

Fetal and neonatal teratoma is rare, but it is the most common tumor of the fetus and meonate. We report seven cases with fetal sacrococcygeal teratoma and two cases with craniocervical teratoma. The diagnosis, further management of pregnancy and birth are described and compared with recent literature. While craniocervical teratoma is associated with very poor prognosis, there are sacrococcygeal teratoma with good survival rate and postoperative good functional results. Very important is prolongation of pregnancy near to term.

Coccyx↗
PubMed1991

Nucleocapsid or spike protein-specific CD4+ T lymphocytes protect against coronavirus-induced encephalomyelitis in the absence of CD8+ T cells.

To investigate the antiviral CD4+ T cell response in coronavirus MHV-JHM-induced encephalomyelitis, spleen and thymic lymphocytes from diseased rats were stimulated in culture with virus Ag, expanded and tested for their specificity to viral proteins and nucleocapsid (N) and spike (S) proteins that had been expressed in bacteria. A strong T cell response specific for N was measurable during acute disease, whereas S-specific T cells were only detectable in rats with a later onset of disease. CD4+ T cell lines with specificity for virus and either N or S protein were established and their influence on the course of a mouse hepatitis virus-JHM infection was investigated. All lines were of the CD4+ phenotype. Both N and S protein-specific CD4+ T cells conferred protection to infected Lewis rats and reduced the amount of infectious virus in the central nervous system. After transfer of CD4+ T cells and challenge with virus, an increase in the antiviral IgM response occurred, but neutralizing antibodies were not detectable during the period of virus clearance. Previous CD8+ cell depletion did not abrogate protection mediated by CD4+ T cell line transfer.

Animals↗
PubMed1990

Astrocytes as antigen presenting cells for primary and secondary T cell responses: effect of astrocyte infection by murine hepatitis virus.

CD4+ T cell lines specific for murine hepatitis virus (MHV) - JHM or myelin basic protein (MBP) proliferated when cultured together with MHC class I and II positive syngeneic rat astrocytes and either inactivated virus or MBP as antigen. The magnitude of the T cell proliferative response was comparable to that seen when thymocytes were used as a source of antigen presenting cells (APC). In contrast, MHC class I and II positive astrocytes were unable to significantly stimulate the proliferation of highly purified populations of naive CD4+ and CD8+ T cells in an allogeneic mixed lymphocyte reaction (MLR). Both T cell populations proliferated when mixed with allogeneic lymph node cells. Infection of the astrocytes with a variant of MHV-JHM (PI-AS22D) did not alter this cells incapacity to stimulate the naive CD4+ and CD8+ T cells to proliferate.

Animals↗
PubMed1990

[The value of the red-green test].

The causes of chromatic aberration were elucidated by Newton in 1704, though in regard to the eye the phenomenon has been a subject of controversy. The chromatic aberration of the eye has long been used to determine refraction. In principle, blurred coloured circles are visible which depend on the chromatic aberration of the eye and lead to perception of different contrasts in the dark optotypes presented in the two coloured fields, depending on the real ametropia or correction conditions. Uniform perception of contrast by the subject is used as the criterion for correction. As regards the red-green test, it appears doubtful that the results are not influenced by protanopia and brunescent cataract. Therefore, the contrast thresholds of 8 protanopic patients and 5 patients with brunescent cataract were examined. This was done using special red and green lenses (produced by VEB Carl Zeiss Jena) under individual conditions with Landolt's rings. Characteristic differences in the contrast thresholds for red and green were found. For bichromatic tests no procedure has been defined, and neither the wave-lengths to be used nor the reference wavelength have been laid down. The results can be affected by numerous physical, physiological and pathological factors. The accuracy and practical usefulness of red-green tests are questionable. Therefore, it does not appear justified to equip ophthalmological examination instruments for such tests.

Accommodation, Ocular↗
PubMed1989

Expression of denitrification enzymes in response to the dissolved oxygen level and respiratory substrate in continuous culture of Pseudomonas stutzeri.

The onset and cessation of the synthesis of denitrification enzymes of Pseudomonas stutzeri were investigated by using continuous culture and defined dissolved oxygen levels covering the full range of transition from air saturation to complete anaerobiosis. Expression of nitrate reductase, nitrite reductase (cytochrome cd1), and N2O reductase was controlled by discrete oxygen levels and by the nature of the nitrogenous oxide available for respiration. N2O reductase was synthesized constitutively at a low level; for enhanced expression, oxygen concentrations were required to decrease below 5 mg of O2 per liter. The threshold values for synthesis of nitrate reductase and cytochrome cd1 in the presence of nitrate were ca. 5 and ca. 2.5 mg of O2 per liter, respectively. With nitrous oxide as the respiratory substrate, nitrite reductase was again the most sensitive to oxygen concentration; however, thresholds for all denitrification enzymes shifted to lower oxygen levels. Whereas the presence of nitrate resulted in maximum expression and nearly uniform induction of all reductases, nitrite and nitrous oxide stimulated preferably the respective enzyme catalyzing reduction. In the absence of a nitrogenous oxide, anaerobiosis did not induce enzyme synthesis to any significant degree. The accumulation of nitrite seen during both the aerobic-anaerobic and anaerobic-aerobic transition phases was caused by the differences in onset or cessation of synthesis of nitrate and nitrite reductases and an inhibitory effect of nitrate on nitrite reduction.

Aerobiosis↗
PubMed1988

Defects in cytochrome cd1-dependent nitrite respiration of transposon Tn5-induced mutants from Pseudomonas stutzeri.

Mutants with defective respiratory nitrite utilization (Nir- phenotype) were obtained by transposon Tn5 insertion into genomic DNA of the ZoBell strain of Pseudomonas stutzeri. Three representative mutants were characterized with respect to their activities of nitrite and nitric oxide reduction, cytochrome cd1 content, and pattern of soluble c-type cytochromes. Mutant strain MK201 overproduced cytochrome c552 about fourfold by comparison with the wild type, but possessed an in vitro functional cytochrome cd1. Mutant strain MK202 lacked cytochrome cd1 and, simultaneously, had low amounts of cytochrome c552 and the split alpha-peak c-type cytochrome. Strain MK203 synthesized nitrite reductase defective in the heme d1 prosthetic group. Irrespective of these biochemically distinct Nir- phenotypes, all mutants preserved the nitric oxide-reducing capability of the wild type. The mutant characteristics demonstrate that cytochrome cd1 is essential for nitrite respiration of P. stutzeri and establish the presence of a nitric oxide-reducing system distinct from cytochrome cd1. They also indicate the functional or regulatory interdependence of c-type cytochromes.

Cytochrome c Group↗
PubMed1988

[Prenatal detection of open neural tube defects in a mass screening program by determination of alpha-fetoprotein concentration in maternal serum].

A partially automatized ultramicroencymimmunoassay developed by the GDR and Cuba should be tested in a mass screening for the prenatal detection of open neural tube defects by measurement of maternal alphafetoprotein concentration (MS-AFP). In the screening program 24,271 pregnant women were included (Berlin/District of Schwerin). In 18,144 patients AFP-concentration in maternal serum was measured as a routine procedure in the care for all pregnant women of the district of Schwerin. The time of MS-AFP determination in this connection was limited from 15th to 18th completed gestational week. 1986 already in 84.9 per cent of all pregnant women of the district of Schwerin MS-AFP concentration could be measured in early pregnancy. The detective rate of open neural tube defects among 24,271 tested pregnant women was 86.1 per cent. AFP concentration was expressed in ng/ml and the "cut off" was set at 2.0 MOM. Infants born with open neural tube defects were reduced by 75 per cent under the conditions of MS-AFP screening. Better results are possible in connection with a progress in the qualification of the following diagnostic steps, if MS-AFP-levels are elevated. Not unexpected and unspecific MS-AFP-elevation was found in connection with twin pregnancies and a higher risk of abortion and the delivery of infants with very low birth-weight less than 1,500 g. A general MS-AFP-screening is recommended for prenatal detection of open neural tube defects all over the country.

Anencephaly↗