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Biomedical subjects

V J Lewis

Publications and source records attributed to V J Lewis.

At least 37 records · Page 2Linked to original sources
PubMed1977

Enzyme-linked immunosorbent assay for chlamydial antibodies.

An enzyme-linked immunosorbent assay (ELISA) detected chlamydial antibodies in human sera. The assay antigen produced in cell cultures infected with Chlamydia psittaci was Formalin-fixed to microplates. Single convalescent-phase sera positive for chlamydial antibodies by a complement-fixation test were positive at even higher dilutions by ELISA. Paired sera with diagnostic rises in complement-fixing antibody showed seroconversion by ELISA also. Control sera from persons with no history of chlamydial infection were negative by both tests. Sera from patients with psittacosis or lymphogranuloma venereum were ELISA positive, indicating that the assay with the antigen used in this study is genus specific rather than species specific.

Antibodies, Bacterial↗
PubMed1977

A rapid fluorescent focus-inhibition test for determining the neutralizing-antibody response to lymphocytic choriomeningitis virus.

Levels of neutralizing antibody to lymphocytic choriomeningitis (LCM) virus in the sera of 66 infected persons were assayed by a rapid fluorescent focus-inhibition test (RFFIT). The test was more sensitive than the mouse-neutralization (MN) test and could be completed in less than 24 h. The RFFIT titers were compared with titers obtained by the indirect fluorescent-antibody (IFA) and complement-fixation (CF) tests. Neutralizing antibody detected by the RFFIT remained positive after IRA, CF and MN antibodies had disappeared. The RFFIT for detection of LCM antibody is specific and reproducible and seems especially useful for determining the incidence and epidemiology of LCM virus infections.

Antibodies, Viral↗
PubMed1976

Accelerated detection of lymphocytic choriomeningitis virus in diagnostic specimens.

Lymphocytic choriomeningitis virus could be demonstrated earlier in mice inoculated with clinical specimens if the mice were sacrificed before they appeared sick for examination by the fluorescent antibody technique. In the procedure, the optimal route for inoculation was intracerebral and the best organ tested for staining was the brain.

Animals↗
PubMed1976

A new technic for obtaining blood from mice.

A practical technic was described for collecting serial blood samples from mice. Blood was obtained from a tail incision made immediately after the mice had been exposed to an ambient temperature of 45 degrees C. Individual samples sufficient for most tests were readily obtained without significant hemolysis. The technic was rapid, reliable, humane, and required no special skill.

Animals↗
PubMed1975

Comparison of three tests for the serological diagnosis of lymphocytic choriomeningitis virus infection.

Levels of lymphocytic choriomeningitis virus antibody were assayed in 62 infected persons. The three tests used were indirect fluorescent antibody (IFA), complement fixation, and neutralization in mice. The sera first became positive by the IFA test, and IFA titers rapidly rose to a relatively high level, with the sera remaining positive long after the antibody detectable by complement fixation had disappeared. The IFA test appeared to be specific. The sera became positive last by the mouse neutralization test; with this test, antibody first appeared several weeks after infection. Virus-infected cells were stable when stored at -60 C, allowing diagnostic sera to be tested promptly by the IFA test. The IFA test for lymphocytic choriomeningitis antibody should increase the number of serological diagnoses, since it is not only rapid and specific, but detects cases not diagnosed by the other methods.

Antibodies, Viral↗
PubMed1972

Indirect hemagglutination test for chlamydial antibodies.

An indirect hemagglutination (IHA) test is described for chlamydial antibodies in psittacosis diagnostic sera; for this test tanned sheep erythrocytes sensitized with a deoxycholate extract of Chlamydia psittaci grown in Vero cell monolayers were used. Adaptation of the IHA test to the Microtiter system decreased sensitivity; nevertheless, the Microtiter-IHA test was more sensitive than the complement fixation test. Lymphogranuloma venereum antibodies also were detected by using antigen extracted from C. psittaci.

Animals↗
PubMed1972

Detection of Chlamydia psittaci by immunofluorescence.

A direct fluorescent-antibody (FA) test was developed to detect Chlamydia psittaci in dural impressions from specimen-inoculated mice. Technical procedures for the test were compared. C. psittaci was found in mice after infection as early by the FA technique as it was by cytochemical staining methods usually used. The lymphogranuloma venereum organism was also stained by conjugated antibody to C. psittaci. A distinctive advantage of the described FA test is that organisms are identified immunologically as members of the genus Chlamydia simultaneously with their detection.

Animals↗
PubMed1968

Effects of three bacterial infections on serum lipids of rabbits.

Alteration of the rabbit serum lipids as a result of three bacterial infections was studied by quantitative thin-layer and gas-liquid chromatography. Anthrax infection slightly changed the serum lipid. Cholesterol did not change, though free fatty acids, triglycerides, and cholesteryl esters doubled, and lecithin increased threefold. Tularemia infection produced drastic changes in the serum lipid content of rabbits, increasing levels of cholesterol over 4-fold, free fatty acids 17-fold, triglycerides 11-fold, cholesteryl esters 2.5-fold, and lecithin almost 3-fold. Pneumococcus infection increased cholesterol 2.5 times, free fatty acids were more than doubled, triglycerides were increased 9.5 times, and lecithin was increased almost 4 times. Gas-liquid chromatographic analysis of the methyl esters of free fatty acids showed only quantitative changes in these acids due to infection. Some possible mechanisms of alteration of serum lipid content are discussed.

Animals↗
PubMed1968

Fatty acid composition of Neisseria species as determined by gas chromatography.

Duplicate cultures of 53 strains representing 9 species of Neisseria were analyzed by gas-liquid chromatography for cellular fatty acids. N. sicca, N. mucosa, N. flava, N. flavescens, N. perflava, N. subflava, and the several serotypes of N. meningitidis examined were found to comprise a fairly homogeneous group on the basis of the percentages of individual fatty acids present. Lactose-fermenting Neisseria also were in this group. N. catarrhalis, however, contained decanoic acid in addition to the acids occurring in the other species. Moreover, the 18 C-saturated and monoenoic acids together constituted 36% of the total fatty acid composition for N. catarrhalis, while the comparable mean value for the other species was less than 13%.

Chromatography, Gas↗
PubMed1967

Characterization of clostridia by gas chromatography. I. Differentiation of species by cellular fatty acids.

Fatty acids of 41 strains representing 13 species of Clostridium were extracted directly from whole cells and examined as methyl esters by gas-liquid chromatography. Both visual and quantitative comparisons of the resulting chromatograms for the presence and relative amounts of large major peaks allowed rapid differentiation of C. perfringens, C. sporogenes, and C. bifermentans from each other and from 10 other species. Each of the three former species possessed a different characteristic fatty acid methyl ester profile that was exhibited by all strains tested within the respective species. Culture age and growth media influenced the relative proportions of certain of the acids, but such differences did not limit species differentiation.

Chromatography, Gas↗
PubMed1967

Cultural characteristics and fatty acid composition of Corynebacterium acnes.

A detailed study of the cultural characteristics and cellular fatty acid composition of 27 isolates of Corynebacterium acnes was performed to establish the properties by which this organism may be identified and characterized. The fatty acids were extracted directly from whole cells and examined as methyl esters by gas-liquid chromatography. Each strain possessed a similar fatty acid profile which was characterized by a large percentage of C15 branched-chain acid. Uniformity in certain biochemical reactions and cultural characteristics was also observed. All strains were catalase-positive, nonmotile, and urease-negative, reduced nitrate, liquefied gelatin, failed to hydrolyze esculin and starch, and gave a positive methyl red test. Glucose, fructose, and glycerol were fermented, but not lactose, salicin, sucrose, maltose, xylose, or arabinose. Production of hydrogen sulfide and indole, fermentation of mannitol, and hemolytic activity were variable characteristics. Two species of the genus Propionibacterium were also tested and found to be similar to C. acnes both in cultural characteristics and fatty acid composition. The results strengthen previous suggestions that C. acnes should be classified in the genus Propionibacterium.

Acids↗