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Biomedical subjects

Y Ma

Publications and source records attributed to Y Ma.

At least 613 records · Page 34Linked to original sources
PubMed1986

Enzyme-linked immunosorbent assay using Mycobacterium tuberculosis antigen 5 for the diagnosis of pulmonary tuberculosis in China.

Measurement of serum IgG antibody to Mycobacterium tuberculosis antigen 5 by enzyme-linked immunosorbent assay was evaluated as a serodiagnostic test for pulmonary tuberculosis in China. The test was 89% sensitive and 94 to 100% specific with high accuracies of prediction. Among 82 tuberculous patients, antibody titer was related to the extent of pulmonary disease. Among control subjects, false positive tests were encountered among 5 of 52 persons with other pulmonary disease and not among 30 healthy subjects. The characteristics of this test compare favorably with those reported for sputum smear examination.

Antibodies, Bacterial↗
PubMed1985

Studies on the chemical modification of hemorrhagic toxin I from five pace snake (Agkistrodon acutus) venom.

The chemical modification of hemorrhagic toxin I (AaHI) from Agkistrodon acutus has been studied. Inactivation was observed upon modification of 3 out of 7 histidine residues with diethyl pyrocarbonate. The His residues are deblocked, accompanied by a return of activity, upon treatment with neutral hydroxylamine. The circular dichroism and fluorescence spectra of diethyl pyrocarbonate inactivated toxin and the native toxin are the same, indicating that modification with diethyl pyrocarbonate does not cause any gross change in the structure of the protein. At least one His residue may thus play an essential role in the enzyme activity. Reaction of the toxin with N-bromosuccimide abolished the enzyme activity, with modification of Trp, Tyr and His residues. The loss of Trp did not parallel the inactivation. Hydrogen peroxide, dioxane and 2-hydroxy-5-nitrobenzyl-bromide treatment damaged the Trp residues, but did not affect the activity. Therefore, the modified tryptophan side chains are not essential for activity. Modification of 2.5-3.0 Tyr residues out of 9 with acetylimidazole did not affect the enzyme activity, nor did nitration of the toxin with tetranitromethane. The reactive tyrosines are apparently not essential.

Amino Acids↗
PubMed1985

Monoclonal antibodies. Their promise for tumor diagnosis, staging, and therapy.

Monoclonal antibodies will have utility as tools for diagnosis, staging, and therapy of malignant disease. Investigators have produced monoclonal antibodies that are directed against tumor-associated antigens and have varying degrees of cross-reactivity against normal tissues. These reagents have homogeneous molecular structure, recognize specific antigenic sites, can be produced in mass quantities, and are easily purified. Clinical trials with monoclonal antibodies are in progress and suggest modest toxicity and potential therapeutic efficacy.

Antibodies, Monoclonal↗
PubMed1984

Evaluation of mycobacterial antigens in an enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of tuberculosis.

Five mycobacterial antigens were compared in an enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of tuberculosis. The antigens studied were an unheated sterile culture filtrate of Mycobacterium tuberculosis, tuberculin purified protein derivative (PPD) from M. tuberculosis (PPDa), purified cytoplasmic protein antigens 5 and 6 from M. tuberculosis, and a PPD prepared from M. kansasi (PPDk). Multivariate analysis of variance showed that geometric mean titres obtained with each of the antigens in ELISA were significantly different in tuberculosis patients and in control groups. The covariation of the ELISA results with the five antigens was highly interdependent. Analysis of receiver operating characteristics revealed that the most accurate test was obtained with antigen 5. M. tuberculosis PPD, M. tuberculosis antigen 6, and M. tuberculosis culture filtrate were, in descending order, less accurate.

Antibodies, Bacterial↗
PubMed1984

Serodiagnosis of pulmonary tuberculosis in Argentina by enzyme-linked immunosorbent assay (ELISA) of IgG antibody to Mycobacterium tuberculosis antigen 5 and tuberculin purified protein derivative.

IgG antibody to Mycobacterium tuberculosis antigen 5 and tuberculin purified protein derivative (PPD) was measured, by enzyme-linked immunosorbent assay (ELISA), in serum samples from 86 patients with active pulmonary tuberculosis and 91 non-tuberculous control subjects from Santa Fé, Argentina. The geometric mean titre for the tuberculosis patients was 74.6 with antigen 5 and 99.5 with PPD. In 91 control subjects the geometric mean titres were 3.6 and 15.6 respectively. Titres were not related to tuberculin reactor status or prior BCG vaccination. At a serum dilution end-point of 1:40, ELISA with antigen 5 had a sensitivity of 81.4% and a specificity of 93.4% for tuberculosis. At 1:40, ELISA with PPD showed a sensitivity of 82.6% and a specificity of 54.9% for tuberculosis. Applied at a serum dilution of 1:40 to a hypothetical model population with a tuberculosis prevalence of 2%, ELISA using antigen 5 would correctly classify 93.2% of persons and ELISA with PPD, 55.5%. At a dilution of 1:80, accuracy is increased to 99.3% with antigen 5 and 83.3% with PPD, but sensitivity decreases to 64.0% with antigen 5 and 72.1% with PPD. Thus, antigen 5 is more accurate than PPD for the diagnosis of tuberculosis using ELISA.

Antigens, Bacterial↗
PubMed1983

Immunochemical analysis of tuberculin purified protein derivative with special reference to United States-Japan antigen 7.

Immunochemical analysis of tuberculin purified protein derivative (PPD) by crossed immunoelectrophoresis and other agar gel techniques revealed substantial variation in antigen levels among PPDs and significant differences that were dependent upon the antiserum used. D-Arabino-D-mannan was identified as a major polysaccharide constituent of PPD; D-arabino-D-galactan and United States-Japan antigen 6 were also present. United States-Japan antigen 7 was found to be a major anodal constituent of all preparations of PPD. This antigen was purified and demonstrated to be a molecularly heterogenous small protein or large peptide with an average molecular weight of approximately 8,000. Antigen 7 possessed tuberculin activity with about one fourth the potency of PPD. When studied in animals sensitized with Mycobacterium tuberculosis and Mycobacterium kansasii, antigen 7 displayed no more tuberculin specificity than PPD.

Chromatography, Affinity↗
PubMed1983

Isolation, characterization, and specificity of a glycoprotein antigen from Mycobacterium kansasii.

We have isolated in highly purified form and characterized a glycoprotein antigen from culture filtrates of Mycobacterium kansasii. Immunoelectrophoretic studies demonstrated that this antigen is present only in M. kansasii among 14 species of mycobacteria studied. It is a potent tuberculin skin test antigen, but skin test reactions to it in sensitized guinea pigs display only limited specificity. Enzyme-linked immunoabsorbent antibody assays of serum samples from patients suffering from diseases caused by M. kansasii, M. intracellulare, and M. tuberculosis display no specificity with this antigen. These findings are best explained by hypothesizing a single highly antigenic determinant that is present as a moiety on many mycobacterial antigens and is widely shared among mycobacteria.

Animals↗
PubMed1982

Molecular cloning of Phaseolus vulgaris lectin mRNA and use of cDNA as a probe to estimate lectin transcript levels in various tissues.

The complete amino acid sequence of a Phaseolus vulgaris cv. Tendergreen lectin was deduced from the nucleotide sequence of a cDNA plasmid. The lectin appears to be synthesized as a prepeptide consisting of a signal sequence of at least 20 residues and a mature protein of 223 amino acids. The 5' region of the lectin cDNA contains four AUG codons, one of which may initiate a 58 amino acid peptide out of phase with lectin translation. Lectin transcripts 1.1 kb long begin accumulating in cotyledons by the 9 mm stage, increasing in amount until about the 16 mm stage, after which their levels dramatically decrease. In addition, larger lectin-specific transcripts are detected in mid-maturation phase cotyledons. A 1.1 kb RNA species in leaves from plants filling their pods hybridizes with lectin cDNA, but no hybridizing RNA is found in primary leaves or roots.

Amino Acid Sequence↗
PubMed1980

Peptide Mapping Reveals Considerable Sequence Homology among the Three Polypeptide Subunits of G1 Storage Protein from French Bean Seed.

The major storage protein, G1 globulin, of bean (cv. Tendergreen) seeds was subjected to limited proteolysis with trypsin, chymotrypsin, papain, proteinase K, and protease V8 and to cleavage with cyanogen bromide and 2-(2-nitrophenylsulfanyl)-3-methyl-3'bromoindolenine. Mapping of peptides separated from each of the three G1 subunits by polyacrylamide gel electrophoresis revealed that many proteolytic cleavage sites were present at similar positions on the subunits. Evidence was adduced that the G1 subunits are homologous in amino acid sequence for about 61% of their length. The remaining region (possibly COOH-terminal) of the subunits appears to be heterologous, with the alpha subunit bearing an additional methionine residue.

Journal Article↗
PubMed1979

Diet-related toxemia in pregnancy. I. Fat, fatty acids, and cholesterol.

Toxemia in pregnancy (preeclampsia)is characteristerized by a combination of at least two of the following clinical symptoms: hypertension, edema, and proteinuria. In three successive trials over three consecutive years, the dietary intake of a selected number of young pregnant women attending a Maternal and Infant Care Program at Tuskegee Institute were evaluated for total lipids, individual fatty acids, and cholesterol. Women with toxemia or with any of the individual symptoms were identified and women without toxemia or these symptoms served as controls. Results were variable from repetition to repetition in all but the toxemia group and the edema group. The consumption of total lipids and cholesterol was significantly greater in all three trials by both the toxemia and edema groups. Also, total saturated, monounsaturated, and polyunsaturated fatty acids were eaten in greater amounts. The greatest differences were in palmitic acid, stearic acid, oleic acid, and linoleic acid. The proportion of unsaturated fatty acids consumed in all groups was very low. All differences could be attributed primarily to breakfast and dinner meals and were found in the milk, meat, and egg food groups. Although satistical correlations were found between lipid intake and toxemia of pregnancy any specific relationship between the two is still unclear.

Adolescent↗