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Biomedical subjects

I Hirsch

Publications and source records attributed to I Hirsch.

At least 55 records · Page 3Linked to original sources
PubMed1991

Expression of an immunogenic region of HIV by a filamentous bacteriophage vector.

Vectors derived from the Escherichia coli filamentous phage, fd-tet, expressing parts of the human immunodeficiency virus (HIV) gag genes were constructed and analyzed. The immunoreactive domain of HIV Gag antigens was produced in the form of a fusion protein, with a phage minor coat protein, called protein III, playing an important role in phage infectivity. A micropanning procedure, utilizing the strong affinity of biotinylated antibody to streptavidin, was applied for the selection of clones. A simple preparation procedure consisting of polyethyleneglycol precipitation of the recombinant phage from the E. coli supernatant allowed us to detect HIV antigens by enzyme-linked immunosorbent assay (ELISA). Cloned FUSE-gag, as isolated using anti-Gag RL4.72.1 monoclonal antibody (mAb), contained a nucleotide sequence coding for 91 amino acids of HIV Gag p24. It specifically reacted with the mAb in the ELISA. Construction of the mAb-selectable phages permitted localization of epitopes for mAb. Infectivity of the phage clone was specifically neutralized by the anti-HIV mAb. Immunoelectroblotting analysis of recombinant phages revealed the presence of an about 65-kDa band reacting with anti-HIV mAb. This Mr corresponded to the size of the fused form of the FUSE 1 protein III. Human sera from HIV-infected and uninfected individuals reacted with recombinant protein III, as well as the original form of protein III.

Amino Acid Sequence↗
PubMed1991

Induction of NF-KB during monocyte differentiation by HIV type 1 infection.

The production of human immunodeficiency virus type 1 (HIV-1) progeny was followed in the U937 promonocytic cell line after stimulation either with retinoic acid or PMA, and in purified human monocytes and macrophages. Electrophoretic mobility shift assays and Southwestern blotting experiments were used to detect the binding of cellular transactivation factor NF-KB to the double repeat-KB enhancer sequence located in the long terminal repeat. PMA treatment, and not retinoic acid treatment of the U937 cells acts in inducing NF-KB expression in the nuclei. In nuclear extracts from monocytes or macrophages, induction of NF-KB occurred only if the cells were previously infected with HIV-1. When U937 cells were infected with HIV-1, no induction of NF-KB factor was detected, whereas high level of progeny virions was produced, suggesting that this factor was not required for viral replication. These results indicate that in monocytic cell lineage, HIV-1 could mimic some differentiation/activation stimuli allowing nuclear NF-KB expression.

Base Sequence↗
PubMed1991

Productive infection of CD4+ cells by selected HIV strains is not inhibited by anti-CD4 monoclonal antibodies.

Differential susceptibility of four diverse HIV strains to inhibition of infection of CD4+ CEM cells by anti-CD4 monoclonal antibodies was studied. The highly cytopathic HIV-1 246 and NDK strains were able to infect CEM cells and undergo several cycles of replication at saturating doses of LEU3-A, OKT4-A, and 13B8-2 monoclonal antibodies, whereas propagation of reference HIV-1 BRU and weakly cytopathic strain HIV-1 PAS was inhibited. Postadsorption treatment by anti-CD4 antibodies had stronger inhibitory effect than did treatment during the virus adsorption period. In parallel experiments, the same monoclonal antibodies successfully blocked syncytium formation between uninfected MT4 cells and CEM cells infected by all four HIV-1 virus strains tested. To explain these seemingly contradictory data we have postulated that anti-CD4 antibodies efficiently inhibit cell-to-cell but not virus-to-cell infection.

Antibodies, Monoclonal↗
PubMed1991

Human transformed trophoblast-derived cells lacking CD4 receptor exhibit restricted permissiveness for human immunodeficiency virus type 1.

We investigated the nature of interaction of the malignantly transformed cell lines of trophoblast origin BeWo, JAR, and JEG-3 with three different human immunodeficiency virus type 1 (HIV-1) isolates (RF, 3B, and NDK). After inoculation with cell-free virus, the persistence of infection was determined for 1 month by monitoring the presence of viral DNA in the cells by the polymerase chain reaction (PCR). Furthermore, the infectious virus in the culture supernatant was assayed with CEM-SS cells, and attempts to rescue the virus by cocultivation with CEM-SS cells were made. Appraised on the basis of the relative amount of viral DNA and the frequency of positive cocultivation. JEG-3 was the most permissive and BeWo was the least permissive cell line. However, when the cells were transfected with two biologically active molecular clones of HIV-1, the BRU and NDK isolates, all three cell lines turned out to support the production of mature virus progeny to the same extent. The abundance of viral DNA sequences in the infected cells varied with the isolate, showing an overall decline from RF to NDK. The amount of viral DNA in the cells and its expression decreased during the period of observation; this decrease was mirrored in an erosion of the virus recovery rate at cocultivation from 71% recovery on day 8 to failure of isolation on day 32. None of the cell lines expressed detectable amounts of cell surface CD4 molecules when assayed by flow microfluorometry and direct radioimmunoassay. Northern (RNA) blot hybridization analysis of both the total RNA and the mRNA did not reveal any CD4-specific message: nonetheless, by using the PCR, sequences specifically related to the CD4 gene were uncovered. The data demonstrate that the trophoblast-derived cell lines are susceptible to infection with HIV and that they support transient viral replication in the initial phases of infection. However, the latent form of infection may persist over a period of several weeks.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Prophylaxis of bacterial infections after bone marrow transplantation. A randomized prospective study comparing oral broad-spectrum nonabsorbable antibiotics (vancomycin-tobramycin-colistin) to absorbable antibiotics (ofloxacin-amoxicillin).

Bacterial infection is a common complication after allogeneic bone marrow transplantation. It is related to the toxic effects of the conditioning regimen on mucosal surfaces, to bone marrow aplasia and to the prolonged lymphopenia with immune deficiency that lasts for several weeks after bone marrow transplantation. We have performed a prospective randomized study comparing two methods of prophylaxis. Group I (OA) received a combination of ofloxacin 400 mg/day and amoxicillin 20 g/day; group II (VTC) received the oral nonabsorbable antibiotics vancomycin 450 mg/day, tobramycin 450 mg/day and colistin 4.5.10(6) units daily, from day -15 to 15 days after discharge from laminar air flow (LAF) rooms. All patients were nursed in LAF rooms with a strict isolation procedure and sterile water and food. They were evaluated daily for clinical symptoms, and bacterial culture samples were taken from the throat, stools and blood twice weekly. Forty-four patients were randomized, 22 entered in group I (OA) and 22 in group II (VTC). There were no differences between the two groups in age (mean 33 years, range 11-54), sex, diagnosis and mean duration of agranulocytosis (21.8 days, range 10-49). Seven patients were excluded because of the selection of a resistant bacteria, 5 were in group I (OA), and 2 were in group II (VTC). The mean duration of fever was 9.2 +/- 7.1 days in group I (OA) and 13.7 +/- 6.8 days in group II (VTC; p = 0.05). There were no significant differences between the two groups in graft-versus-host disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Legal aspects of work-related eye injuries.

As court-appointed medical advisors in the speciality of ophthalmology for the Israeli Labour Courts, we are called upon to assist in making decisions on work-related eye injuries or illnesses. In this report we present seven cases of eye injuries which workers claimed were caused by work accidents. Each case helps to illustrate the various guidelines we use in making a medical judgement as to whether or not a specific ocular problem was, indeed, the result of a work accident.

Accidents, Occupational↗
PubMed1990

A recombinant vaccinia virus expressing hepatitis B virus middle surface protein. Restricted expression of HBV antigens in human diploid cells.

Several vaccinia virus recombinants inducing the synthesis of the middle surface (M) protein of hepatitis B virus (HBV) were constructed. One of them, denoted v137, was examined in some detail. The virus replicated nearly to the same extent in various cell lines, viz. human embryo diploid fibroblast LEP and MRC-5 cells, rabbit embryo fibroblast REF cells, TK- rat RAT-2 cells, and green monkey CV-1 cells. However, the production of M protein was found considerably lower in the human LEP and MRC-5 than in the other cells examined. In addition, the kinetics of M formation were different in these two cell systems, LEP cells lagging significantly behind CV-1 cells. The low-level production of M protein in LEP cells was not increased by repeated v137 passages in LEP cells, nor by a passage in a laboratory worker accidentally infected with the v137 virus, nor by shortening the leader sequence preceding the translation initiation codon. The greater part of the M antigen was found to be cell associated, more so in the cells of human than monkey origin. From the major HBV S antigen (HBsAg) isolated from the plasma of chronically infected subjects, the antigen released by cell destruction differed by binding to polymerized human albumin. This property was utilized in ELISA to detect anti-preS2 antibody. Rabbits inoculated intradermally with the v137 virus developed antibodies reactive in this assay as well as with a synthetic peptide corresponding in the amino acids 14-34 of the NH2 terminus of the HBsAg preS2 region.

Animals↗
PubMed1990

The env gene variability is not directly related to the high cytopathogenicity of an HIV1 variant.

HIV1-NDK is a Zairian HIV1 isolate which is unique because of its high cytopathic effect on T lymphoblastoid cell lines. Its sequence analysis has indicated 30% divergence with HIV1-LAV/BRU HTLVIII B prototype in the env gene encoding for the envelope glycoprotein gp120. In order to correlate the highly cytopathic properties with the env genetic variability, recombinants between the HIV1 prototype and HIV1-NDK have been constructed, including HIV1-NDK env gene, and their cytopathic phenotypes were analyzed. The viral hybrid containing all HIV1 prototype sequences except a large fragment including the total HIV1-NDK env gene remained at a low cytopathic phenotype. Our results suggest that sequences other than the env gene namely p18 gag, vif, and vpr are required for the high virulence of HIV1-NDK.

Animals↗
PubMed1990

Differences in replication and cytopathogenicity of human immunodeficiency virus type 1 (HIV-1) are not determined by long terminal repeats (LTR).

The growth properties of molecular clones of a highly cytopathic Zairian HIV1-NDK and prototype viruses were compared to correlate genetic variations with biological changes. The cloned HIV1-NDK retained the highly replicating cytopathic phenotype and formed larger syncytia than the prototype. One of the major differences in the alignment of the nucleotide sequence of the HIV1-NDK and HIV1-BRU prototypes was localized in the negative regulatory element (NRE) of the long terminal repeat (LTR). In a chloramphenicol acetyl transferase (CAT) assay, we failed to detect a significant difference between LTR promoter activity of the prototype and HIV1-NDK, suggesting that the LTR of both phenotypes had a similar function. The complete recombinant provirus DNA molecules bearing HIV1 LTR derived from one phenotype and the rest of the genomes from the other phenotype were constructed and transfected. The high cytopathogenicity of both the original and the chimeric viruses was correlated with the high speed of virus replication. Cytopathogenicity, morphology of syncytia, and replication kinetics of the recombinant viruses were determined by the functions coded within an internal part of HIV1 genome, covering the gag to env region, which were, however, not within LTR.

Animals↗
PubMed1990

Presence and type specificity of papillomavirus antibodies demonstrable by immunoelectron microscopy tests in samples from patients with warts.

Sera from 75 patients with warts were tested for antibodies against human papillomaviruses (HPVs) in an immunoelectron microscopy test. A group of 40 patients' sera were tested against a pooled suspension of the HPVs extracted from their warts and 90% of the sera were found to be antibody-positive. Prior to serological investigation viruses from a second group of 35 patients were typed by dot blot hybridization with HPV-1 and HPV-2 DNA. According to these results the patients were divided into type 1, type 2 and non-1, non-2 virus carriers. Sera of these patients were first tested for antibodies reactive with their homologous viruses and then for antibodies against type 1 virus. More than 80% of the patients possessed antibodies against their homologous viruses, but only a small minority of sera from type 2 and non-1, non-2 virus carriers were reactive with type 1 viruses. These results suggest that the antibody reactive in the immunoaggregation test is type-specific.

Adolescent↗
PubMed1990

Presence of antibody reactive with synthetic peptide derived from L2 open reading frame of human papillomavirus types 6b and 11 in human sera.

Nine oligopeptides corresponding to segments of different open reading frame (ORF) proteins of human papillomavirus (HPV) 6b and HPV-16 were prepared and tested for reactivity with human sera in enzyme-immunoassay (ELISA). Of these only heptadecapeptide derived from L2 ORF of HPV-6b, and encoded also by L2 ORF of HPV 11, was reactive with some human sera. Over 400 human sera of different origin were tested for the presence of antibody to this antigen. While less than 15% of sera from healthy subjects or cervical carcinoma patients were found antibody positive, sera from the majority of condylomata accuminata (CA) patients were reactive. The antibody titres varied from 1:10 (initial serum dilution) to 1:80; in this respect there was no marked difference between sera from CA patients and the other subjects. The prevalence of antibody was higher among promiscuous than nonpromiscuous women. This is in line with the assumption that sexual intercourse is the most important route of HPV 6 and 11 transmission.

Amino Acid Sequence↗
PubMed1988

Epstein-Barr virus nuclear antigen type 1 binding: electron microscopy.

Epstein-Barr virus (EBV) nuclear antigen type-1 (EBNA-1) was extracted and purified from Raji cells by chromatography on DNA-Sepharose and Blue-dextran Sepharose. Its complexes with plasmid pM765-10 derived from EBV (strain M-ABA) DNA were visualized by electron microscopy. The criteria of specificity were as follows: (1) preferential binding of EBNA-1 to the ori-P region of pM765-10; (2) specific enlargement of EBV DNA/EBNA-1 complexes with anti-EBNA-1 (IR-3) IgG antibody; and (3) resistance of the resulting EBV DNA/EBNA-1/anti-EBNA-1 antibody complexes to treatment with 1.5 M NaCl. The optimal conditions for the formation of EBV DNA/EBNA-1 complexes were 50 to 150 mM NaCl and pH 6.0. A balanced equilibrium of EBNA-1 and pM765-10 was necessary to achieve both a high yield and specificity of EBV DNA/EBNA-1 complexes.

Antigens, Viral↗
PubMed1988

Quantitative analysis of the signal-averaged QRS in patients with arrhythmogenic right ventricular dysplasia.

Temporal signal averaging of the surface QRS (V1 + V3 + V5) was performed in 16 patients with arrhythmogenic right ventricular dysplasia and in 16 normal subjects. The differences between ARVD patients and normals were large for the filtered QRS duration (FQRSd) (146.2 +/- 18.9 ms vs. 91.8 +/- 4.1 ms, P less than 0.000001), the late potential duration (LPd) (83.5 +/- 23.3 ms vs. 23.6 +/- 4.6 ms, P less than 0.00001), the LPd/FQRSd ratio (53.9 +/- 10.1% vs. 25.8 +/- 5.1%, P less than 0.00001), the filtered QRS amplitude (234.0 +/- 61.1 microV vs. 429 +/- 94.2 microV, P less than 0.001), and the root mean square voltage of the signals in the terminal 40 and 50 ms of the FQRS (RMS40 and RMS50) (18.4 +/- 10.0 microV vs. 118.4 +/- 49.8 microV, P less than 0.0005 and 27.9 +/- 19.2 microV vs. 217.0 +/- 66.3 microV, P less than 0.000002). RMS50 less than 40 microV discriminated best between ARVD and normals (81% sensitivity and 100% specificity). The right-sided predominance of the abnormalities in ARVD was demonstrated by the significantly longer FQRSd and LPd, and the higher ratio LPd/FQRSd in right than in left precordial leads. The arrhythmia susceptibility did not seem to influence the presence of or properties of LP in the ARVD group. Patients with multiple QRS morphologies during ventricular tachycardia (VT) had, compared with patients with only one type of VT, longer LPd (108.3 +/- 46.4 ms vs. 64.2 +/- 31.7 ms, P less than 0.02) and lower RMS40 voltage (9.4 +/- 9.9 microV vs. 25.4 +/- 21.6 microV, P less than 0.05). The relative heart volume was positively correlated with delayed activity, but an enlarged heart was not a pre-requisite for the presence of LP. The method thus identifies changes which are specific to ARVD. The findings indicate that certain electrical or morphological conditions are required for the occurrence of arrhythmias.

Adolescent↗