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Biomedical subjects

M Margalith

Publications and source records attributed to M Margalith.

At least 55 records · Page 3Linked to original sources
PubMed1985

Detection of rotavirus-specific IgG antibodies by immunoperoxidase assay and enzyme-linked immunosorbent assay.

An indirect immunoperoxidase assay (IPA) has been developed for determination of IgG antibodies to rotavirus. The technique employed as antigen, SA-11 infected MA 104 cells, which were air-dried on glass slides and acetone-fixed. In parallel, rota-specific IgG antibodies were determined by enzyme-linked immunosorbent assay (ELISA). Specific IgG antibodies to rotavirus were determined in sera of healthy children and in sera of patients suffering from gastroenteritis. A good correlation (r = 0.92) and (r = 0.98) for healthy children and patients, respectively, was found between IPA and ELISA techniques. The IPA technique is rapid and simple and positive results, because of the intensive staining, are easily read by low-power light microscope. The potential application of IPA and ELISA methods in serodiagnosis of rotavirus infections is discussed.

Adult↗
PubMed1984

Acquisition of antibodies to various Coxsackie and Echo viruses and hepatitis A virus in agricultural communal settlements in Israel.

A seroepidemiological study was conducted to measure the antibody prevalence for eight different enteric viruses. These include seven "classical" enteroviruses, ie, Coxsackie virus types A9, B1, B3, B4 and three ECHO virus types 4, 7, and 9, as well as hepatitis A virus (HAV), recently classified as enterovirus 72. Sera samples were obtained from 791 residents living in 29 agricultural settlements (kibbutzim) with a total population of 15,950. The results indicated that the acquisition of antibodies to Coxsackie and ECHO viruses occurred at a significantly earlier age than to HAV. Prevalence of antibodies to Coxsackie and ECHO viruses at two to four years of age was 40%-69%, in contrast to 4% for HAV. At age 5-17 years, 85% had antibodies to five or more of the seven "classical" enteroviruses, as compared with 10% to HAV. The latter steeply increased to 63% for age group 18-24 years and reached a peak of 95% for age group 50 years and older. Prevalence of antibodies to ECHO and Coxsackie viruses were often found to be higher in in females than in males, within the age group of 18 years and older, but not in age groups 18 years and younger. Prevalence of antibodies to HAV was observed to be much higher in males than in females 18-24 years of age. No significant difference was found in the prevalence of individuals harboring antibodies to three or more and even up to five or more Coxsackie and ECHO viruses between those HAV-negative versus those HAV positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Cytotoxicity of arabinofuranosyladenine and erythro-9-(2-hydroxy-3-nonyl) adenine to Epstein-Barr virus producer and nonproducer lymphoma cells in culture.

Adenine arabinoside (ara-A) at a concentration of 5-10 micrograms/ml inhibited the multiplication of two Epstein-Barr virus (EBV) producer lymphoblastoid cell lines B . 95-8 and P3HR-1. The nonproducer EBV genome carrier cell line, Raji, and the EBV negative cell line, Ramos, were not significantly affected. The cytotoxicity of ara-A to Ramos, Raji and P3HR-1 cells increased in the presence of 1 . 10(-5)M erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), an inhibitor of adenosine deaminase. EHNA alone was noncytotoxic and even had a mild stimulatory effect on cell multiplication. The level of adenosine deaminase in Raji and Ramos cells was similar to that observed in human cord blood lymphocytes, as determined by starch gel electrophoresis. A low level of adenosine deaminase was detected in P3HR-1 cells and the enzyme was absent from B . 95-8 cells. These findings indicate that in the absence of adenosine deaminase, ara-A cytotoxicity increased. Ara-A (5 micrograms/ml) and EHNA (1 . 10(-5)M) had no effect on human cord blood lymphocytes stimulated by phytohemagglutinin as measured by (3H) thymidine uptake, but had some effect on protein A-stimulated lymphocytes. Ara-A, however, inhibited the transformation of human cord blood lymphocytes by EBV, which EHNA did not inhibit. The synthesis of EBV capsid antigen in B . 95-8 cells was also inhibited by ara-A and slightly stimulated by EHNA.

Adenine↗
PubMed1982

Differential inhibition of DNA polymerase and RNase H activities of the reverse transcriptase by phosphonoformate.

Three potential inhibitors of reverse transcriptase activities, phosphonoformate (PF), phosphonoacetate (PAA), and ethyl-diethyl phosphonoformate (Et-PF), were compared in this study. Only PF was found to inhibit the DNA polymerase activity of the purified reverse transcriptase of Moloney murine leukemia virus (M-MuLV) and avian myeloblastosis virus (AMV). The degree of DNA polymerase inhibition was linear with PF concentration; 50% inhibition was achieved at 10 muM. Whereas PF inhibited both the RNA and DNA dependent DNA polymerase activities, the RNase H activity of the reverse transcriptase was unaffected. Both the endogenous DNA polymerase activity in detergent disrupted virus and the activity of the purified enzyme with the isolated virus genome 70S RNA were inhibited by PF. However, higher concentrations of PF were needed to inhibit the endogenous reaction. The inhibition by PF appeared to be reversible and noncompetitive with respect to the substrate deoxythymidine triphosphate (dTTP). Addition of PF after the initiation of DNA synthesis immediately arrested the reaction.

Animals↗
PubMed1982

Organophosphorous compounds as inhibitors of EBV infection and transformation.

Phosphonoformic acid trisodium salt (PF), ethyl diethyl-phosphonoformate (Et-PF), phosphonoacetic acid (PAA), ethyl diethyl phosphonoacetate (Et PAA), ethyl diethyl-2-phosphonopropionate (Et-2-PPA) and ethyl diethyl-3-phosphonopropionate (Et-3-PPA) were tested as inhibitors of EBV virus capsid antigen (VCA) synthesis in B.95-8 cells by immunofluorescence. The most effective inhibitors were: PF, inhibition of 96.74 percent of VCA synthesis at a concentration of 500 microM and PAA, inhibition of 82.05 percent of VCA synthesis at a concentration of 250 microM. Much higher concentrations of the other compounds were needed for inhibition with lower efficiency. Synthesis of EBV nuclear antigen (EBNA) was not inhibited by PF or PAA. However, only PF and PAA inhibited the transformation of human cord blood lymphocytes (CBL) by EBV, as measured by 3H-thymidine uptake, even when added 24 hours after infection. The degree of inhibition of transformation correlated with the concentration. Complete inhibition of CBL transformation by EBV was achieved by 1,000 microM PF and 500 microM PAA, which were noncytotoxic. Removal of PAA from B.95-8 cells cultivated in the presence of high concentrations of PAA for 15 weeks restored VCA synthesis without full concomitant production of transforming EBV.

Antigens, Viral↗
PubMed1980

On the continuous culturing of B.95-8 cells in the presence of phosphonoacetic acid.

Lymphoblastoid B.95-8 cells were cultured for four months and three weeks in the presence of increasing concentrations (50--200 microgram/ml) of phosphonoacetic acid (PAA). Several weeks after removal of the PAA, the cultures, in parallel with untreated B.95-8 cells, were tested for the presence of: 1) Epstein-Barr virus (EBV) viral capsid antigen (VCA), and b) transformation of human cord blood lymphocytes. There was no difference in the percentage of cells exhibiting VCA in the B.95-8 PAA treated and untreated cells. However, transformation assays indicated 10 times less transforming virus in culture supernatant harvested from B.95-8 cultures treated with PAA, as compared with the control cultures. Electron microscopic studies indicated the presence of virus particles in B.95-8 control cells and their almost complete absence in the PAA-treated cells.

Antigens, Viral↗
PubMed1980

Esters of phosphonopropionic and phosphonoacetic acids: effect on synthesis of Epstein-Barr virus (EBV) antigens and on transformation of cord blood lymphocytes by EBV.

Cell cytotoxicity, inhibition of synthesis of Epstein-Barr virus (EBV) viral capsid antigen (VCA), nuclear antigen (EBNA) and transformation of human cord blood lymphocytes (CBL) by EBV, were studied using the disodium salt of phosphonoacetic acid (PAA), ethyl diethyl-phosphonoacetate (Et-PAA) and two derivatives of phosphonopropionic acid: ethyl diethyl-2-phosphonopropionate (Et-2-PPA) and ethyl diethyl-3-phosphonopropionate (Et-3-PPA). These substances were tested on EBV producing cell lines, B.95-8 and P3HR1. VCA and EBNA synthesis were determined by immunofluorescence and transformation of CBL by 3H-thymidine uptake. Up to 100 micrograms/ml of PAA were not toxic to 2.10(5) cells. Et-PAA, Et-2-PPA and Et-3-PPA were nontoxic at concentrations up to 2000 micrograms/ml. PAA inhibited 82.05% of EBV VCA synthesis at a concentration of 50 micrograms/ml. Et-PAA inhibited 47.01% of VCA at a concentration of 100 micrograms/ml and 78.09% at a concentration of 2000 micrograms/ml. Et-2-PPA inhibited 41.04% of VCA at 100 micrograms/ml and 80.87% when used at 2000 micrograms/ml. Et-3-PPA inhibited 35.06% of VCA at 100 micrograms/ml and 69.92% at 2000 micrograms/ml. Removal of the substances restored VCA synthesis. EBNA synthesis was not affected by these substances. PAA completely inhibited the transformation of human CBL by EBV at a concentration of 100 micrograms/ml. Et-PAA at a concentration of 2000 micrograms/ml completely inhibited 3H-thymidine uptake. ET-2-PPA was less effective whereas Et-3-PPA had almost no effects at the same concentration.

Animals↗
PubMed1979

Phosphonoacetic acid: inhibition of transformation of human cord blood lymphocytes by Epstein-Barr virus.

Phosphonoacetic acid disodium salt (PAA) inhibited the transformation of human cord blood lymphocytes by Epstein-Barr virus (EBV) at concentrations of 50-100 microgram/ml. At these concentrations, PAA had no effect on the multiplication of EBV transformed human lymphoblastoid cells or on the survival of human cord blood lymphocytes. The transformation of human cord blood lymphocytes by the B95-8 strain of EBV was measured by 3H-thymidine uptake, 5 days or more after infection. The degree of inhibition of transformation was correlated with the relation between the input of EBV and the concentration of PAA in the experiment. PAA inhibited the transformation even when added 24 h after EBV infection, but had no effect when added 48 h after EBV infection. The inhibitory effect of PAA could be overcome by its removal and normal 3H-thymidine uptake was restored even after 6 days of inhibition. The specificity of the inhibitory effect on EBV induced transformation of human cord blood lymphocytes is discussed.

Animals↗
PubMed1970

Induction of simian virus 40 antigen in BSC1 transformed cells.

Heating to 45 C induced in virus-free clones of simian virus 40 (SV40) transformed BSC(1) cells the synthesis of SV40 viral antigen, as evidenced by immunofluorescence. Up to 3.8% of the cells exhibited viral antigen 72 hr after heating to 45 C for 30 min. Depletion of arginine from the medium of the heated cells enhanced and increased the percentage of cells synthesizing viral antigen to 11%. Cytosine arabinoside completely inhibited the induction of the viral antigen. No infectious virus was recovered from the cells in which synthesis of viral antigen was induced. However, small amounts of infectious SV40 virus were rescued from the BSC(1) transformed cells by fusion with rabbit kidney cells or by treatment with mitomycin C.

Animals↗