Biomedical subjects
Publications and source records attributed to S G Rubin.
We suggest a closed form expression for the path integral of quantum transition amplitudes. We introduce a quantum action with parameters different from the classical action. We present numerical results for the harmonic oscillator with weak perturbation, the quartic potential, and the double well potential. The quantum action is relevant for quantum chaos and quantum instantons.
A number of peptides, fragments of the envelope protein E of the tick-borne encephalitis virus (Sofjin strain), were synthesized. Their binding to the polyclonal antiserum to protein E was studied. Rats were immunized with both the free peptides and their KLH-conjugates, and the resulting antisera were tested for their reactivity toward protein E and for their neutralizing activity toward the virus in cell culture. The only peptide corresponding to the 98-113 sequence of protein E was shown to be bound by the protein E antiserum in EIA. Two-fold immunization of rats with KLH-conjugates of the peptides corresponding to the 98-113, 130-143, and 394-403 sequences of protein E resulted in antipeptide antibodies capable of binding the native protein E, and the antibodies to the 98-113 and 394-403 peptides were capable of neutralizing the virus.
The arrangement of envelope protein epitopes of tick-borne encephalitis viruses (TBEV) (persulcatus or eastern subtype, Sofjin strain and ricinus or western subtype, Minsk-256 strain) and Kyasanur Forest disease virus (KFDV) was investigated using competitive binding of monoclonal antibodies against the Sofjin E protein. The E protein of TBEV Sofjin strain forms three antigenic domains: E1, E2 and E3, represented by 12, 9 and 2 epitopes respectively; two additional epitopes stand alone. Domains E1 and E2 are heterogeneous. On the epitope map of the Minsk-256 strain domain E3 remains intact, domains E1 and E2 overlap and the relative arrangement of virus-neutralizing epitopes from E1 and E2 domains is changed. The epitope map of KFDV is significantly dissimilar to TBEV. The viruses can be distinguished by epitopes with identical serological reactivity. A satisfactory agreement between our epitope maps and previously published antigenic models of flavivirus envelope protein (Guirakhoo et al., 1989; Mandl et al., 1989a) was observed. The main difference of our map is that domains corresponding to domains B and C (Sofjin strain) and A, B and C (Minsk-256 strain) in Heinz's model are overlapping. The results of competition analysis depend on the nature of the antigen (virion or purified protein) and the immunoassay technique.
The largest cyanogen bromide fragment (GP-14,5; coordinates 78-176) of E protein belonging to the envelope of the tick-borne encephalitis (TBE) virus (Far Eastern subtype, strain Sofjin) interacted with five out of twelve E-specific monoclonal antibodies (MAbs). Having compared; efficiencies of some MAbs binding to the antigens of TBE viruses of Far Eastern and West European subtypes and primary structures of analogous peptides of these viruses, we suggested the epitopes of these MAbs to be located in the vicinity of 89 and/or 116-th amino acid residues of E protein. Effect of denaturing agents and reduction followed by carboxymethylation on the protein E antigenic properties was studied.
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Cloned cDNA and synthetic deoxyoligonucleotides, complementary to various parts of the genomic RNA of tick-borne encephalitis virus (TBEV), strain Sofjin, were used to distinguish between strains of TBEV and other flaviviruses. The cDNA probe hybridized with strains of TBEV and related flaviviruses of the TBE complex except for Powassan virus, and it did not react with flaviviruses of the Japanese encephalitis and dengue subgroups. Viruses of the TBE complex and some strains of TBEV were differentiated from TBEV strain Sofjin by the thermal stability of RNA-DNA hybrids. Negishi and louping-ill viruses were the most closely related to TBEV strain Sofjin, among viruses of the TBE complex. Eight strains of TBEV isolated in different geographical areas from different sources were tested by dot-hybridization with 11 deoxyoligonucleotide probes. The probes revealed genetic variations among strains of TBEV. The pattern of hybridization correlated with the source of virus strains: TBEV strains isolated from TBE patients reacted with more probes than strains isolated from ticks. Within a group of epidemic strains of TBEV there was a correlation between the geographical area of isolation and similarity to TBEV strain Sofjin.
RNA of a flavivirus-tick-borne encephalitis virus (Far-East, type 1, strain Sofin) was subjected to reverse transcription and the DNA copy was transformed into double-stranded DNA by action of E. coli DNA-polymerase (Klenow's fragment) without primer. The hairpin structures were removed by S1 nuclease. Oligo-dC ends were attached to ds-cDNA thus obtained, and this DNA was annealed with pBR322 plasmid cut by PstI and equipped with oligo-dG termini. The recombinant plasmids were cloned in E. coli HB101. Of the 360 TcrAps clones obtained, 187 clones efficiently hybridized with partially degraded 32P-RNA of TBE virus. The sequence of the insert of one of the clones was determined by the Maxam-Gilbert method. The 720 b.p. sequence is translatable into an amino acid sequence without interruption. Nearby the 3'-terminus of the insert, the sequence ACACAGG is present which is homologous with that found in RNA of the flavivirus West Nile.
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Similar physicochemical characteristics were found with strains of Crimean hemorrhagic fever (CHF) and Congo viruses. The particle size, sedimentation coefficient, buoyant density, weight of the particles as well as morphology and morphogenesis of these viruses were similar to those of other members of the Bunyaviridae family. Data are presented on reproduction of CHF virus in cell cultures and on the inner structure of its virion.
Morphological characteristics of Crimean Hemorrhagic Fever Virus indicate that it is closely related to the Bunyaviridae family. However, there are some features (e.g. formation of crystal-like patterns in infected cells) demonstrating differences to the other known Bunyaviridae.
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A point prevalence survey, using a questionnaire, was performed in three general hospitals to investigate the problem of elderly patients blocking acute-hospital beds. A total of 1010 occupied general beds were surveyed and all patients, over the age of 60 years, who had been in hospital more than four weeks, and who, in the opinion of medical and nursing staff, were no longer in need of the facilities of a general hospital, were investigated. Forty-eight patients (4.8 per cent of the total) were found to be genuinely in bed inappropriate to their needs. Rehabilitation, together with assessment of these patients, appeared disorganized and lacked consistency, and decisions regarding suitable 'disposal' appeared to be made without sufficient consultation and conformed to no detectable pattern. The main reason for the continuing bed occupancy of the patients was the length of the waiting lists for alternative residential accommodation and the main single medical factor preventing discharge home or to a hostel was the problem of mobility. By interviewing staff and patients and scrutinizing the questionnaires, it was found that 23 patients (48 per cent) were only suitable for transfer to a long-stay hospital. Of these, however, 15 (31 per cent) could be placed in specialized accommodation if some degree of nursing care, at present not available, was provided.
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A new method for intratypic antigenic differentiation of poliovirus strains has been developed. The method is based on the use of cross-absorbed sera in neutralization tests where virus is titrated by the cytopathic effect. Qualitative differences between the antigenic structure of vaccine and "wild" strains as well as between some "wild" strains of the same serologic type have been found. The method may be used in practical laboratories.