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Biomedical subjects

J L Melnick

Publications and source records attributed to J L Melnick.

At least 217 records · Page 12Linked to original sources
PubMed1975

Studies on the survival and fate of enteroviruses in an experimental model of a municipal solid waste landfill and leachate.

In laboratory scale municipal solid waste lysimeters containing simulated refuse, and seeded with either laboratory or field strains of poliovirus type 1 and echovirus type 7, viruses were not detected in the lysimeter leachate produced over a 4-month period. In addition, viruses were detected in the lysimeter refuse contents after termination of lysimeter operation. These results appeared to be due to virus retention in the lysimeter caused by virus adsorption and virus inactivation. Evidence for virus inactivation was provided by the results of experiments on virus inactivation in composite leachate samples. Evidence for virus adsorption was supported by the rapid adsorption of viruses to various municipal solid waste components in the presence of a salt similar in composition to the major inorganic salts of leachates.

Adsorption↗
PubMed1975

Cell-mediated immunity in guinea pigs to subunits derived from hepatitis B surface antigen.

Guinea pigs immunized wit- hepatitis B surface antigen (HBSAg), types adw and ayw, and with two polypeptides (400,000 and 24,000 molecular weight) developed cell-mediated immunity (CMI), as determined by radioimmunoassay. Peritoneal exudate (PE) cells from guinea pigs immunized with the 40,000-molecular-weight polypeptide migrated poorly (30 to 88% inhibition) after challenge with the immunizing subunit or with purified HBSAg, type gdw or ayw. Response of the same PE cells to the 24,000-molecular-weight subunit was significantly reduced. Similar but less striking evidence for CMI was observed was PE cells derived from guinea pigs inoculated with purified type-specific HBSAg or with the 24,000-molecular-weight polypeptide. Humoral responses were predictable and showed a reasonable degree of correlation with the CMI response. PE cells from control animals inoculated with normal human serum or polyacrylamide gel were not inhibited after challenge with purified preparations of HBSAg or with the 400,000-molecular-weight polypeptide, but did show CMI with their respective immunogens. In addition, PE cells from guinea pigs inoculated with normal human serum were inhibited from migrating after challenge with the 24,000-molecular-weight subunit, suggesting that the latter may contain an antigenic determinant related to a human serum protein.

Animals↗
PubMed1975

Production of antibody to individual polypeptides derived from purified hepatitis B surface antigen.

Purified preparations of hepatitis B surface antigen (HBsAg) were solubilized with sodium dodecyl sulfate and urea under reducing conditions and subsequently fractionated by preparative sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis (PAGE). Pools of the individual fractions eluted from the preparative PAGE were concentrated and purified further by analytical PAGE. Five purified polypeptides were isolated from HBsAg, types adw and ayw, with molecular weights of 19,000, 24,000, 27,000, 35,000, and 40,000. Each preparations was emulsified in Freund complete adjuvant and injected into guinea pigs. Antibody to each HBsAg type was measured by radioimmunoassay. The 19,000 molecular weight polypeptide derived from ayw particles and the 27,000 molecular weight subunit obtained from both types failed to elicit an antibody response. The other three polypeptides derived from the ayw particles elicited group-specific antibody responses. Similar group-specific reactivities were observed in the testing of anti-adw 35,000 and anti-adw 40,000 molecular weight polypeptide sera. However, guinea pigs immunized with the 19,000 and the 24,000 molecular weight polypeptides of the adw type produced antibody that reacted preferentially with adw particles. This indicates that either these subunits carry predominately d determinants or that, because of the low levels of material used for inoculation, no immune response or an undetectable one was elicited to the a or w components.

Animals↗
PubMed1975

Demonstration of infectious DNA in transformed cells. III. Correlation of detection of infectious DNA-protein complexes with persistence of virus in simian adenovirus SA7-induced tumor cells.

Primary tumors induced in newborn hamsters by simian adenovirus SA7 were investigated in transfection experiments. Infectious DNA-protein complexes were readily detected in both the supernatant and pellet fractions obtained by a modified Hirt extraction procedure; DEAE-dextran was required for infectivity to become manifest. Infectivity could be abolished by exposure to DNase, but it was unaffected by SA7-specific antiserum or RNase, and only partially inactivated by trypsin treatment. SA7 tumor cells serially passaged either in tissue culture or in hamsters yielded infectious DNA complexes much less frequently and appeared to evolve into nonyielder cell lines. When large numbers of cells were lysed, intact virus could be recovered from all the primary tumors and from some of the subcultured cell lines. There was a correlation between the persistence of complete virus and the presence of infectious DNA-protein complexes. When the tumor cells carried very small amounts of intact virus, infectious DNA complexes could still be detected; when virus could no longer be detected in the tumor cells, infectious DNA complexes could no longer be found. The results suggest that a portion of the infectious DNA moieties exists as viral DNA-protein complexes in the tumor cells.

Adenoviridae↗
PubMed1975

Parvoviridae.

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Parvoviridae↗
PubMed1975

Cyclic appearance of defective interfering particles of herpes simplex virus and the concomitant accumulation of early polypeptide VP175.

Serial passage of undiluted herpes simplex virus types 1 and 2 resulted in cyclic production of infectious and defective virions. Defective virus production was characterized by the appearance of a new species of viral DNA with a higher bouyant density in CsCl than standard viral DNA. Measurement of the infectivity titer and DNA synthesis revealed that the defective particles interfered with the replication of standard virions and stimulated the overproduction of a large molecular weight (175,000 daltons) polypeptide.

Cell Line↗
PubMed1975

Humoral and cellular immunity in guinea pigs to polypeptides derived from HBsAg-containing particles.

Recent studies in this laboratory have shown that purified HBsAg contains at least 7-9 polypeptide subunits ranging in molecular weight (MW) from 18,000 to 120,000; at least three of these are associated with carbohydrates. In addition, two glycosphingolipids have been extracted which are structurally similar to the blood group antigenic substance. The glycoproteins and glycolipids are of particular interest since it has been reported that carbohydrate is associated with the antigenic activity of HBsAg. Antisera to these subunits have been produced in guinea pigs. These results stimulated further 'in vivo' investigations into the possible development of a subunit vaccine which would exclude genes of a viral or cellular nature and would not be infectious. Guinea pigs were immunized with HBsAg, subtypes adw and ayw, and with two polypeptides (40,000 MW and 24,000 MW) in complete Freund's adjuvant. Control animals were inoculated with normal human serum or with polyacrylamide gel. Animals were boostered on day 14 and tested on day 30 for the development of cell-mediated immunity (CMI) by the macrophage inhibition assay, and for humoral immunity by PHA and RIA. Migration of peritoneal exudate (PE) cells was inhibited 30-88% in guinea pigs immunized with the 40,000-MW polypeptide when challenged with purified HGsAg, subtype adw or ayw, or with the 40,000-MW preparation, but the results were inconclusive with the 24,000-MW subunit. Similar evidence of CMI was observed with PE cells derived from guinea pigs inoculated with purified subtype-specific HBsAg or with the 24,000-MW polypeptide. Humoral responses were predictable, and showed a reasonable degree of correlation with the CMI response. Control animals failed to respond to challenge with purified preparations of HBsAg or the 40,000-MW polypeptide, but did show CMI with their respective immunogens and - in the case of guinea pigs inoculated with normal human serum - with the 24,000-MW subunit, suggesting that the latter may contain an antigenic determinant related to a human serum protein.

Animals↗