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Biomedical subjects

A Friedmann

Publications and source records attributed to A Friedmann.

At least 73 records · Page 4Linked to original sources
PubMed1988

HLA class II allelic variation and susceptibility to pemphigus vulgaris.

The autoimmune dermatologic disease pemphigus vulgaris (PV) is associated with the HLA serotypes DR4 and DRw6. Susceptibility to PV could be conferred either by sequences shared between the DR4 and DRw6 haplotypes or by different sequences in these haplotypes. We have examined the distribution of DR and DQ beta-chain and DQ alpha-chain alleles in PV patients and in control subjects by hybridization with oligonucleotide probes and sequence analysis of in vitro amplified DNA. Ninety percent (34/38) of the DR4 haplotypes in patients contain a specific DR beta I sequence present in 36% (16 of 44) of DR4 controls (P = 0.001). This sequence is also found in DRw6 haplotypes. However, it is present in only 25% (6 of 24) of DRw6 patients. The results of our analysis indicate that predisposition to PV is conferred by different sequences in DR4 and DRw6 haplotypes. The DR4 susceptibility is highly associated with the Dw10 DR beta I allele, implicating the polymorphic residues in the third hypervariable region. The DRw6 susceptibility is strongly associated with a rare DQ beta allele (DQB1.3). This allele differs from a common DQ beta allele (DQB1.1) only by a valine----aspartic acid substitution at position 57.

Alleles↗
PubMed1987

Fractionation of Theiler's virus-infected BHK21 cell homogenates: isolation of virus-induced membranes.

A purified fraction containing unique membranes entrapping virions was isolated from homogenates of cells infected with the DA strain of Theiler's virus, after high-speed centrifugation through a sucrose gradient. This fraction, sedimented at 45-50% sucrose, was only found in cells infected with the DA strain but not in cells infected with the GDVII strain of Theiler's virus or in mock-infected cells. Immunogold staining of the membranes entrapping virions, using antivirus IgG antibodies, revealed that the membranes entrapping virions did not incorporate viral capsid antigens.

Animals↗
PubMed1987

Synthesis of long viral complementary DNA from 7.5 Kb poly A+ RNA templates.

The poly A+ RNA of the WW and GDVII virus isolates, belonging to the Theiler's murine encephalomyelitis virus group, were used as templates for cDNA synthesis. Since several secondary structures were present along these viral RNAs the reverse transcriptase was prematurely displaced from the RNA templates and only short cDNA molecules could be synthesized. Therefore a reliable and reproducible procedure for the synthesis of long cDNA transcripts, that can be directly used for cloning into respective plasmid or phage vectors, was developed. The precise conditions and kinetics of the several enzymatic reactions were studied. The use of methylmercury hydroxide for first strand synthesis, a correct choice of Klenow polymerase for second strand synthesis and the use of vertical gel electrophoresis in combination with zone centrifugation for removal of the excess linkers were found to be of paramount importance for the synthesis of long, up to intact, 7.5 Kb cDNA transcripts.

Animals↗
PubMed1987

Human leukocyte antigens (HLA) class I and class II on sperm cells studied at the serological, cellular, and genomic levels.

The expression of human leukocyte antigens (HLA) on highly purified human ejaculated sperm cells was studied using the sensitive enzyme-linked immunosorbent assay (ELISA) technique and a wide panel of monoclonal antibodies to class I and class II HLA. In addition, the stimulatory capacity of these cells was tested in mixed cultures of lymphocytes and spermatozoa, and the levels of RNA homologous to the HLA class I and class II genes were determined. The results obtained using the ELISA indicate that the class I and class II HLA serologically defined antigens are weakly expressed on the cell surface of the mature spermatozoa. Highly purified sperm cells consistently stimulated heterologous lymphocytes but not when HLA-DR compatibility was observed between stimulator and responder. The proliferative response of lymphocytes induced by sperm cells was lower than the response obtained in a lymphocyte-lymphocyte combination, though the kinetics of the response were similar in both cases. In addition, it was found that spermatozoa contained RNA species homologous to HLA class II DR beta and DQ beta genes sequences but not to HLA class I sequences. The levels of these RNA species were significantly reduced after interferon stimulation. Lymphocytes that served as positive control were found to contain RNA complementary to both HLA class I and class II genes.

Antibodies, Monoclonal↗
PubMed1987

Monoclonal anti-I-A antibody reverses chronic paralysis and demyelination in Theiler's virus-infected mice: critical importance of timing of treatment.

Susceptibility to demyelination caused by the WW isolate of Theiler's murine encephalomyelitis viruses is linked to class II genes of the major histocompatibility complex. SJL/J (H-2s) mice, expressing only I-As class II gene products of the major histocompatibility complex, are highly susceptible to Theiler's murine encephalomyelitis virus infection with the WW virus isolate, with chronic paralysis and severe inflammation and demyelination in the central nervous system. The effect of in vivo administration of anti-I-As monoclonal antibodies on Theiler's murine encephalomyelitis virus infection was observed. SJL/J mice were treated in various protocols pre- or postinfection. Anti-I-As monoclonal antibody reversed chronic paralysis and reduced inflammation and demyelination when given after the establishment of persistent infection. The effect was long lasting, but clinical signs, inflammation, and demyelination recurred 2 months after treatment ceased. Anti-I-As antibodies had no effect on viral titers within the central nervous system. The timing of the administration of monoclonal antibodies was critical. Administration of anti-I-As before the establishment of the persistent infection resulted in fatal encephalitis.

Animals↗
PubMed1986

Theiler's virus replication in isolated Schwann cell cultures.

Theiler's murine encephalomyelitis viruses causing both fatal encephalitis (GDVII virus) and chronic demyelinating disease (WW virus) are capable of replicating in isolated Schwann cell cultures. Light microscopy combined with immunohistochemical staining of viral antigens revealed that large numbers of Schwann cells infected with the two viruses show cytopathic effect (rounding) and contain viral antigens. Electron microscopy of virus-infected Schwann cells shows that the morphological alterations that the cells undergo following infection by the two virus isolates are different. In the early stages of GDVII and WW virus infection, different inclusion bodies are formed in the cells cytoplasm. At late stages of the infection GDVII virions are found in all infected cells and are arranged in crystalline arrays around inclusion bodies. In contrast, in WW virus-infected Schwann cells only in few cells virions were observed and they appeared aligned between two membrane units.

Animals↗
PubMed1986

In vitro cytotoxicity and demyelination induced by Theiler viruses in cultures of spinal cord slices.

The cytopathic effects caused by Theiler viruses to myelinated organotypic spinal cord cultures was studied by light and electron microscopy. Heavily myelinated cultures, 2-3 weeks in vitro were infected with WW and GD VII viruses. Mock infection served as control. On light microscopy cytopathic effects and demyelination became evident about 16-17 hr after infection. Demyelination observed in WW virus-infected cultures was much more pronounced than in cultures infected with GD VII viruses. The myelin in mock-infected cultures remained undamaged. Electron microscopy revealed that in control cultures cells were intact, exhibiting numerous synapses and a network of axons enwrapped by multilayered myelin sheaths. Virus-infected spinal cord slices showed that a more severe cytotoxicity was caused by GD VII virus than by WW virus. The cytopathology included accumulation of cytoplasmatic vacuoles, margination of chromatin, synapse and cell disintegration, and various degrees of demyelination. Several GD VII virions were observed, arranged in crystalline arrays, mainly in electron-opaque cells, but not within axons. WW virions on the other hand were only occasionally encountered.

Animals↗
PubMed1986

Polymorphism of the HLA DR1 haplotype in the Israeli population investigated at the serological, cellular, and genomic levels.

In the present report, we used serological, cellular, and restriction fragment length polymorphism (RFLP) to investigate the DR1 haplotype in the Israeli population. We describe an Israeli homozygous typing cell (HTC), HLA-Dw"LVA", which defines a new lymphocyte-activating determinant associated with Bw65, DR1 and distinct from Dw1. The parents of this donor, non-Ashkenazi Algerian Jews, are first cousins and share HLA-Cw8,Bw65,BfS,DR1,DQw1,DPw4. No specificity could be assigned to HLA-Dw"LVA" using the 91 Ninth Workshop HTCs. Two families and forty unrelated DR1 individuals were studied with Dw"LVA" and a panel of DR1/Dw1 HTCs. HLA-Dw"LVA" showed segregation as a single determinant within families. This new specificity was present in 24 out of 40 (60%) unrelated DR1 individuals, indicating that in the Israeli population Dw"LVA" is the main lymphocyte-defined determinant associated with the serologically defined DR1 specificity, in contrast to non-Jewish Caucasoids where DR1 is significantly associated with Dw1. The vast majority of Dw"LVA"-positive carriers were also Bw65 carriers, indicating that Bw65,DR1, Dw"LVA" may represent a typical allele combination in the Israeli population. The RFLP analysis established the correlation of certain RFLPs with Dw1 and Dw"LVA". In addition, we describe a cluster of FRLPs that may correspond to a new Dw subtype associated with DR1, for which no serological and cellular reagents have been described so far.

DNA Restriction Enzymes↗
PubMed1985

Visualization of the fate of inactive influenza viruses in Daudi cells by electron microscopy.

The replication of active and inactivated influenza viruses in Daudi lymphoma cells was studied by immunofluorescence and electron microscopy. In a previous study, we demonstrated that active and heat-inactivated X47 (H3N2) virus arrested Daudi cell growth by inhibiting cellular DNA synthesis while formalin-treated X47 virus did not. Transmission electron microscopic studies revealed that both the active and the heat-inactivated X47 virus penetrated into the cells. Only the active X47 (XA) virus replicated completely in Daudi cells and produced new viral particles by budding. The formalin-treated X47 virus did not damage or change the cells, and although the viral particles remained adsorbed to the cells, there was little penetration. The heat inactivated X47 virus (which was the most effective, non-virulent, oncolytic agent we studied) was visualized as large aggregates of particles adsorbed to the cell surface by electron microscopy. The cells themselves formed clumps. The viral aggregation and cell clumping likely resulted from the loss of viral neuraminidase activity due to heat treatment. The penetration of heat-inactivated viral particles was massive and involved numerous particles. Production of new viral particles was not demonstrated in this study even though nucleocapsids from the original virus were found in the cytoplasm. Thus, it appears that the massive penetration of the viral particles into cells damages the plasma membrane and may be responsible for the oncolytic potential of the heat-inactivated virus on Daudi cells.

Burkitt Lymphoma↗
PubMed1984

Electron microscopic study of the development of Theiler's murine encephalomyelitis viruses propagated in vitro.

The changes occurring in the nuclei and cytoplasms of BHK21 cells during infection with the two subgroups of Theiler's murine encephalomyelitis viruses were studied by electron microscopy. The nuclear alterations include: formation of clumps and margination of chromatin, enlargement of perinuclear spaces, deformation and displacement of the nucleus. The cytoplasmic alterations include: increase in the number of ribosomes, extensive proliferation of smooth membranes at the centrosphere of infected cells, appearance of electron-dense bodies, and decrease in number and swelling of mitochondria. At late stages of infection, GDVII and FA viruses which represent the virulent subgroup, form crystalline arrays in the cytoplasm of infected cells. A few mechanisms by which these crystals may be formed are discussed. The later stages of TO viruses infection, which cause a persistent infection in mice, differed markedly from those of GDVII and FA viruses. TO viruses were found to be arranged in a single file between two sheets of membranes. A model for this unique structure is presented.

Animals↗
PubMed1984

Persistent and acute central nervous system infections are caused by Theiler's murine encephalomyelitis viruses which differ in RNA composition but code for only slightly different proteins.

The RNA and proteins for four representatives of the two subgroups of Theiler's murine encephalomyelitis viruses were studied. The large RNase T1-resistant oligonucleotides, when mapped along the RNA molecules, were found to be differently distributed in the two subgroups. Replicative form RNAs of two representatives were partially denatured, and the denaturation maps obtained were found to be similar but not identical. In addition, the analysis of the tryptic maps of the capsid proteins of all four isolates revealed that only small differences in the peptide map patterns exist among these viruses. The correlation of these findings with the pathogenicity of Theiler's viruses is discussed.

Animals↗
PubMed1983

Characterization of Vilyuisk virus as a picornavirus.

The V-1 strain of Vilyuisk virus, isolated from the cerebrospinal fluid of a chronic case of encephalomyelitis in Siberia and subsequently passaged 41 times in mice, was examined to determine its serological relationship to Theiler's murine encephalomyelitis virus (TMEV) and encephalomyocarditis (EMC) virus and some physicochemical characteristics of the virion. On the basis of virion size (28 nm), icosahedral symmetry, buoyant density (1.33 g/ml), sedimentation coefficient (150S), and capsid polypeptide profile, Vilyuisk virus appears to belong to the family Picornaviridae. Acute phase mouse antisera were used to study the antigenic relatedness of Vilyuisk, GDVII (the prototypic strain TMEV), and EMC viruses by enzyme-linked immunosorbent assay (ELISA). The results indicate that Vilyuisk and GDVII viruses are similar but distant subtypes, and that Vilyuisk and EMC viruses are unrelated.

Animals↗
PubMed1983

Proteins induced in tissue culture by four isolates of Theiler's murine encephalomyelitis virus.

The proteins specified by four Theiler's murine encephalomyelitis virus isolates in infected BHK-21 cells were studied. Their processing, sensitivity to trypsin, and the changeover after viral infection from synthesis of cellular proteins to synthesis of viral proteins were determined by one- and two-dimensional gel electrophoreses. The molecular weights and isoelectric points of the structural and nonstructural proteins of DA and WW isolates, which represent the less virulent subgroup of Theiler's murine encephalomyelitis virus, and of GDVII and FA isolates, which represent the virulent subgroup, were found to be the same. The sensitivity of DA and GDVII isolates to trypsin, as purified virions, and in infected cell extracts was similar. The shut-off of cellular protein synthesis in cells infected with the same two isolates and the changeover to the synthesis of viral proteins appeared to have the same pattern. These findings are interesting since the two subgroups of Theiler's murine encephalomyelitis virus differ in their pathogenicity, intracellular development in infected BHK-21 cells, and RNA composition, as determined by RNase T1 fingerprinting analysis.

Animals↗
PubMed1983

GDVII and DA isolates of Theiler's virus: proteins attached to the 5' end of the RNA are bound covalently to the same nucleotides.

GDVII and DA picornaviruses, which represent two biologically distinct subgroups of Theiler's murine encephalomyelitis viruses, were analyzed to detect the presence of a RNA-linked protein, VPg. It was found that the single-stranded RNA genomes isolated from the virions of both viruses contain a protein of approximately 7,000 daltons, which is covalently linked to the 5' end of the RNA. Like in other picornaviruses (e.g., poliovirus and encephalomyocarditis virus), the terminal nucleotide adjacent to the protein was found to be pUp. The possibility that differently charged VPg species exist is also mentioned.

Base Sequence↗
PubMed1983

The origin of multiple sex chromosomes in the gerbil Gerbillus gerbillus (Rodentia: Gerbillinae).

The sex chromosomes of the partly sympatric species of gerbils Gerbillus pyramidum and G. gerbillus (Mammalia: Gerbillinae) were investigated by a variety of light- and electron-microscope methods, including DNA replication banding and synaptonemal complex (SC) techniques. The sex-chromosome mechanism of G. pyramidum is of the maleXY:femaleXX type, whereas that of G. gerbillus is of the less common maleXY1Y2:femaleXX system. The results include the demonstration that the X chromosomes of both species are compound. One segment is added to the X chromosome of G. pyramidum, leading to an increase in length from the standard 5% to approximately 7.3%, whereas two different extra segments increase the length of the X chromosome of G. gerbillus to approximately 11% of the length of the haploid genome. In both cases the extra material is autosomal and is also represented in the respective Y chromosomes. Classifying heterochromatin by the variation in staining quality was helpful in elucidating the possible origin of the different chromosome segments, including the pericentromeric regions. Observations on meiotic chromosome pairing and chiasma formation have confirmed the homologies established by band comparisons. The occurrence of chiasmata between the sex chromosomes supports the autosomal origin of the pairing segments. These and other findings have been interpreted in the framework of a multistep evolutionary model. This sequence starts from a hypothetical pair of sex chromosomes, the X element of which amounts to 5% of the haploid genome, and leads through three translocations involving two pairs of autosomes and one pericentric inversion to the most complex situation of this series, manifested in G. gerbillus. The adaptive value, if any, of autosome incorporation into the sex chromosomes repeatedly occurring here is unknown. It is, however, a remarkable fact that in one species, G. gerbillus, the complex sex-chromosome constitution is conserved over vast geographic distances, and in the other, G. pyramidum, the compound X and Y chromosomes withstand change in the face of extreme autosome restructuring.

Animals↗