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Biomedical subjects

F A Lewis

Publications and source records attributed to F A Lewis.

At least 109 records · Page 6Linked to original sources
PubMed1979

Immune responses during human schistosomiasis mansoni. VI. In vitro nonspecific suppression of phytohemagglutinin responsiveness induced by exposure to certain schistosomal preparations.

Simultaneous in vitro exposure of human peripheral blood mononuclear cells to phytohemagglutinin-P (PHA) and either soluble schistosomal egg antigenic preparation (SEA) or soluble cercarial antigenic preparation (CAP) obtained from Schistosoma mansoni resulted in decreased responsiveness as compared to exposure to PHA alone. The addition of a soluble adult worm antigenic preparation (SWAP) did not predictably alter PHA responses in this system. The suppression due to in vitro exposure to either SEA or CAP was expressed whether the lymphocyte donors were S. mansoni patients (early infection, chronic, or treated), or uninfected subjects. The degree of suppression was related to the concentration of SEA used, and the timing of exposure. Preexposure to SEA for 3 days before the addition of PHA resulted in more potent suppression. However, a delay in the time of the addition of SEA of 6 and 24 hr after PHA exposure decreased and eliminated, respectively, its suppressive capacity. SEA and CAP were not directly toxic to responding cells, and appeared to exert their nonspecific suppressive influences through T lymphocyte-related mechanisms. It was observed that although these suppressive events could be induced and observed in vitro, the responsiveness of S. mansoni patient lymphocytes to PHA was equal with that of uninfected controls.

Antigens↗
PubMed1978

The 1976 influenza epidemic in Melbourne.

Some aspects of the 1976 influenza epidemic are described and compared with findings in previous years. Rapid diagnostic techniques gave encouraging results, but were less sensitive than conventional techniques. A higher rate of virus isolation was obtained from nasopharyngeal aspirates than from pooled nose and throat swabs.

Adolescent↗
PubMed1978

Prevalence of antibody to hepatitis A and polioviruses in an unimmunized urban population.

A large group of sera collected in 1954-1955 from people living in the metropolitan area of Melbourne, Australia, was tested for neutralizing antibody to polioviruses 1,2 and 3 and for antibody to hepatitis A virus by solid phase radioimmunoassay. The age-specific prevalence of antibody to each virus was remarkable similar, being highest in the elderly and in persons of low socioeconomic status. Antibody to each virus was acquired early in life, with more than half the population showing evidence of infection by the age of 15 years.

Adolescent↗
PubMed1978

Delayed hypersensitivity to hapten-skin protein conjugates in guinea pigs sensitized to benzo(a)pyrene.

Guinea pigs were sensitized to 3,4-benzo(a)pyrene, by epicutaneous application or by footbad injection in Freund's complete adjuvant. Conjugates of benzo(a)pyrene and guinea pig skin protein formed by ultraviolet radiation could elicit cutaneous delayed hypersensitivity and could inhibit the migration of macrophages obtained from guinea pigs sensitized to the carcinogen. Extracts of benzo(a)pyrene-treated guinea pig skin and conjugates formed in vitro with benzo(a)pyrene isocyanate were unable to consistently elicit delayed hypersensitivity reactions in vivo or in vitro. The results indicate a high degree of hapten-carrier specificity to contact sensitivity to benzo(a)pyrene.

Animals↗
PubMed1978

Humoral immune responses in human hepatosplenic schistosomiasis mansoni.

The development of hepatosplenic schistosomiasis in humans cannot always be related to the intensity of infection. A study was designed to identify different humoral immunologic responses to Schistosoma mansoni in patients with and without hepatosplenic disease. Twenty-four patients with active hepatosplenic disease were closely matched for age, sex, and fecal egg counts with twenty-four patients with only intestinal disease. A serum sample from each of these patients was tested for antibodies to the major soluble egg antigen (MSA1) by radioimmunoassay, for total and IgM antibodies to egg and worm antigenic preparations by ELISA, and for its ability to suppress antigen stimulated lymphocyte blastogenesis. No difference was found using these assays between the hepatosplenic and the intestinal schistosomiasis patients.

Adolescent↗
PubMed1977

A study of the prevalence of rotavirus infection in children with gastroenteritis admitted to an infectious diseases hospital.

In a 12 month survey of infants and children with gastroenteritis admitted to Fairfield Hospital, Melbourne, rotavirus was found in approximately 42% of patients. This virus was detected more often during the winter months, particularly in children aged between 12 months and 3 years. Detection of rotavirus by electron microscopy was found to be more sensitive than by counterimmunoelectrophoresis. Routine bacterial and viral studies revealed that bacterial pathogens and common enteric viruses were associated with relatively few cases of gastroenteritis. There is little doubt that rotavirus is the most important aetiological agent of acute gastroenteritis in yvirus is the most important aetiological agent of acute gastroenteritis in young children in Melbourne.

Age Factors↗
PubMed1977

Changes in liver nuclear protein metabolism after a single dose of urethane to suckling mice.

Treatment of 8-9-day-old C57BL/A mice with a single carcinogenic dose of urethane, at 1.2 mg/g body wt., resulted in an immediate decrease in liver DNA synthesis reaching a maximum at about 16-18 h after injection, the rate of synthesis returning to normal after 48 h. When the nuclear proteins were radiolabelled, the non-histone protein (NHP) fraction showed a significant decrease in specific activity 8-18 h after injection of urethane and slight increase in specific activity after 24 h. Histone and residual proteins did not show any significant change. The liver NHP were analysed by isoelectric focusing (IEF) and sodium dodecyl sulphate (SDS) electrophoresis in polyacrylamide gels. The latter technique failed to show any distinctive differences but IEF results indicated some quantitative and qualitative changes in protein content and synthesis were induced by the urethane treatment. The most noticeable change in the stained gels was an increase in a protein component having a pI of 7.35 and the appearance of new bands at pI's of 7.85 and 5.55 in the 18 h treated livers. However, the [3H]tryptophan labelling pattern indicated that this was not due to an increased synthesis of these components. 24 h after urethane there appeared to be an increased rate of synthesis of some of the major components of the mixture, particularly at the pI 5.65 region. Histone and residual protein fractions were also analysed by electrophoresis and showed no difference between treated and control livers.

Animals↗
PubMed1977

Isolation of dinitrophenyl-skin protein conjugates by immunoadsorbent chromatography.

Immunoadsorbent columns charged with rabbit anti-dinitrophenyl (DNP) antibody were used to isolate and concentrate DNP-protein conjugates from the 105,000 g supernate of extracts prepared from guinea pig epidermis previously painted with dinitrofluorobenzene (DNFB). Conjugates isolated in this manner elicited positive delayed hypersensitivity skin tests when injected intradermally into DNFB-sensitized animals. Dinitrophenylated epidermal protein conjugates prepared in vitro were capable of specifically inhibiting the migration of peritoneal exudate cells obtained from DNFB-sensitized guinea pigs. These results demonstrate the application of immunoadsorbent chromatography and the migration inhibition assay to the further definition of the epitopes involved in contact sensitivity.

Animals↗
PubMed1977

Failure of plasma from human schistosomiasis mansoni patients to protect mice from Schistosoma mansoni cercarial challenge.

Plasma samples obtained from patients with well defined Schistosoma mansoni infections, or control subjects, were passively transferred to CF1 mice. Three, 12, or 24 hours after passive transfer, the recipient and control mice were challenged with either 200 or 600 live cercariae, and the adult worm burdens or schistosomula lung recoveries, respectively, were determined 7 weeks or 6 days after challenge. None of the human plasmas afforded the recipient mice protection against the development of schistosomes. Worm and larval yields were equivalent in all cases, even though many of the patient plasmas were shown, as assessed by an in vitro eosinophil-dependent cytotoxic antibody assay, to contain high levels of antischistosomular antibody.

Animals↗
PubMed1977

Modification of the lung recovery assay for schistosomula and correlations with worm burdens in mice infected with Schistosoma mansoni.

The kinetics of recovery of schistosomula from the lungs of previously-unexposed CF1 mice were studied following infection with Schistosoma mansoni cercariae. Lung tissue fragments were incubated from 3 to 48 hr and the completeness of recovery of viable schistosomula was determined. The recovery of schistosomula from the lungs was shown to correlate closely with 7-week worm recoveries. With the additional incubation described, the lung recovery assay may provide a more defined indicator of protective immunity. Based on the data generated by these analyses, it is predicted that under these conditions schistosomula arrive in the lungs from 3 to 7 days after infection, and that they sojourn there for a 3-day period.

Animals↗
PubMed1976

Instability of rat liver chromatin and other nuclear non-histone proteins in alkaline solution.

Non-histone proteins from rat liver nuclei and chromatin were shown to be hydrolysed in 0.1M or-1M-NaOH solutions both at 4 degrees and 18 degrees C; 24h in 1M-NaOH at 18 degrees C is sufficient to break down approx. 77% of these proteins to low-molecular-weight peptides. Loss of protein material banding in the region of pH5.5-8.0 has been demonstrated by isoelectric focusing in polyacrylamide gels, and fine high-molecular-weight bands are no longer visible on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. The results indicate that care must be taken when analysing non-histone-protein fractions to avoid exposure to alkaline pH conditions.

Animals↗
PubMed1976

Comparison of rhinovirus-sensitive HeLa cells and human embryo fibroblasts for isolation of rhinoviruses from patients with respiratory disease.

Rhinovirus-sensitive HeLa cells (HeLa "R") and human embryo lung fibroblasts (HEL) were compared for the isolation of rhinoviruses from patients with respiratory disease. In the period May 1970 to December 1974, 526 rhinoviruses were isolated from 517 patients, 32% in both cell types, 59% in HeLa "R" only, and 9% in HEL only. The annual isolations in HeLa "R" were between 1.7 and 4 times greater than in HEL cells and may have been due to changes in the sensitivity of the cells or the prevalence of serotypes favoring the HeLa "R" cells. Acid lability was more easily demonstrated in HeLa "R" than in HEL cells, because the infectivity titers obtained were 10- to 100-fold higher.

Cell Line↗