Search PubMed⌕ Search

Biomedical subjects

F B Johnson

Publications and source records attributed to F B Johnson.

At least 109 records · Page 6Linked to original sources
PubMed1975

Effect of environmental pH on adenovirus-associated virus.

The influence of environmental pH on AAV was studied in infectious virus titrations, induction of CF antigens production of infectious virus, induction of immunofluorescent stainable antigen, and aggregation of the viral particles. The pH of the medium was found to influence the titer of virus stocks in that less virus was registered at acid pH's, giving differences of up to 105 TCID50 in HEK and HEp-2 cells. Less infectious virus was produced in KB cells, and decreased amounts of CF antigen appeared at acid pH's. However, increased levels of detectable intracellular FA antigen appeared at acid pH's. Electron microscopic examination of AAV particles negatively stained at various pH's showed increasingly large aggregates of particles as the pH was lowered. Under the acid conditions studied, the adenovirus helper and cell activities were only slightly suppressed, with the greatest effect due to aggregation of the virus particles.

Adenoviridae↗
PubMed1974

Production and reactivity of immune sera specific for HADEN virus polypeptide antigens.

Antisera were prepared against the three structural polypeptides of HADEN virus dissociated with sodium dodecyl sulfate. These immunological reagents were used in immunofluorescence tests to study the kinetics and location of polypeptide antigen appearance in infected cells. These sera did not neutralize virus infectivity, did not cross-react with adenovirus-associated virus-infected cells, and reacted in complement fixation tests with sodium dodecyl sulfate-dissociated virus, but not with complete virus antigen. The polypeptide antigens were heat labile, and all appeared in infected cells at least 2 h prior to whole-virus antigen.

Adenoviridae↗
PubMed1972

Immunological reactivity of antisera prepared against the sodium dodecyl sulfate-treated structural polypeptides of adenovirus-associated virus.

The preparation of antisera to the three purified sodium dodecyl sulfate (SDS)-treated polypeptide components (VP1, VP2, VP3) of adenovirus-associated virus (AAV) type 3H is described. In immunofluorescence tests (FA), these antisera stained heat-stable antigens with distinct morphologies in cells co-infected with either adenovirus or herpes simplex virus. Kinetic studies of antigen formation showed that VP1 antiserum first stained the cytoplasm (14 hr) and later (by 18 hr) stained both cytoplasmic and intranuclear areas. VP2 antiserum stained only discrete intranuclear areas, and VP3 antiserum stained nearly the entire nucleus. All three VP antigens appeared at about the 14th hr postinfection, about 2 hr prior to the appearance of whole virion antigen. The VP antisera cross-reacted in FA with AAV types 1 and 2 (all at one-eighth of the homologous titer), but did not react with other parvoviruses, i.e., rat virus, hemadsorbing enteric virus of calves, minute virus of mice, or H-1 virus. These non-neutralizing antisera reacted specifically with SDS-treated AAV virion antigens in complement fixation and immunodiffusion tests, and antiserum prepared against SDS-treated helper adenovirus structural polypeptides reacted with adenovirus polypeptide antigens. All antisera to SDS-treated polypeptides were specific for new antigens revealed on the dissociated peptides and did not react with whole virions, whereas whole-virion antisera did not cross-react with the polypeptide antigens. These findings suggest that antigens unique to the polypeptides of AAV are revealed by SDS treatment and that these antigens can be detected in cells prior to the folding of the polypeptides into the molecular configuration they possess as virion subunits. These results also indicate that at least one AAV polypeptide component is synthesized in the cell cytoplasm.

Adenoviridae↗
PubMed1971

Structural proteins of adenovirus-associated virus type 3.

Three major structural proteins were found in adenovirus-associated virus (AAV) type 3H virions which were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The molecular weights of the polypeptides were determined to be approximately 66,000 (VP1), 80,000 (VP2), and 92,000 (VP3). The component having a molecular weight of 66,000 comprised about 80% of the total virion protein in the major AAV-3H particle, and the other two components comprised about 10% each. Proteins of the same molecular weight were found in the minor dense AAV-3H virion, but the 80,000- and 92,000-molecular-weight components were present at about one-half the concentration. The AAV-3H virion contains about 72 molecules of VP1 and 8 and 7 molecules of VP2 and VP3, respectively.

Adenoviridae↗
PubMed1968

Purification of staphylocidal beta-lysin from rabbit serum.

A cationic protein of rabbit serum bactericidal for Staphylococcus aureus was purified. The specific activity per unit of protein of the purified staphylocidal preparation was approximately 37,000 times greater than that of the serum from which it was isolated. Similar techniques were used to purify serum beta-lysin active against Bacillus subtilis approximately 24,000 times. The staphylocidal activity cannot be attributed to the same beta-lysin active against B. subtilis, lysozyme, or antibody-complement systems. The concentrations of staphylocidal beta-lysin in the sera of the five mammalian species studied did not correlate with their beta-lysin activities against B. subtilis. The two beta-lysins are similar in that both were heat-stable, sensitive to trypsin digestion, had molecular weights near 6,000, and were found in higher concentrations in serum than in plasma. Furthermore, similar techniques can be used to absorb and elute both substances in highly purified forms using cellulose asbestos filter pads and ion exchange chromatography on carboxymethyl cellulose. In contrast to the beta-lysin against B. subtilis, the staphylocidal beta-lysin was not released from blood platelets, and it was inactive in the presence of heparin, sodium citrate, sodium oxalate, ethylenediaminetetraacetic acid, acidic phospholipids, and acid pH values. A variety of proteins, including those of normal serum, preferentially inhibited the bactericidal activity of staphylocidal beta-lysin but not the beta-lysin against B. subtilis.

Animals↗
PubMedDate not supplied

Preoperative chemo-radiotherapy in advanced head and neck cancer.

In a prospective evaluation, two preoperative courses of methotrexate, bleomycin, and cisplatin combined with 2,000 rad/10 fractions ("chemo-radiotherapy") yielded 78% responses rates in previously untreated advanced head and neck cancer. Similarly staged patients receiving preoperative irradiation of 5,000 rad alone had a 67% response rate. Treatment-related mortality in the chemo-radiotherapy patients was equal to that seen with standard combinations of surgery and preoperative or postoperative irradiation. At 24 months, disease-free survival is 47% with chemo-radiotherapy vs 33% with standard therapy; however, patients benefiting most from the former approach were those with T4 primary lesions or N3a neck nodes.

Aged↗