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Biomedical subjects

M Kuo

Publications and source records attributed to M Kuo.

31 records · Page 2Linked to original sources
PubMed1994

Diversity of ethnic and racial VNTR RFLP fixed-bin frequency distributions.

To examine the impact that intra- and interracial genetic diversities have on VNTR RFLP-fragment-size distributions, a multiracial (East Asian, African American, U.S. Southwest Hispanic, and European Caucasian) and multiethnic (Chinese, Japanese, Korean, and Vietnamese) database has been constructed for the following loci: D1S7, D2S44, D4S139, and D10S28. Homogeneity between samples was examined using the Komologorov-Smirnov two-sample test for RFLP fragment sizes and a log-likelihood test for fixed-bin frequencies with theoretical and Monte Carlo empirical significance levels. Small but significant differences between theoretical and empirical significance-level distributions were observed with both procedures, particularly with the latter. The significance levels of the two types of tests were poorly correlated. Statistically significant differences in fragment-size and fixed-bin distributions were found within and between races, with greater differences occurring between races. Cluster analysis and principal components analysis, using different similarity measures, did not support the hypothesis of greater intra- than interracial diversity, which suggests that ethnic variation can be conservatively estimated by racial variation.

Cluster Analysis↗
PubMed1993

Immunoaffinity chromatography of recombinant Amb a I in the presence of a denaturing agent.

Recombinant proteins expressed in E. coli are often sequestered into inclusion bodies and require the use of denaturing agents in order to solubilize them. The recombinant form of Amb a I, the major allergen from short ragweed pollen, is one such protein. In some cases solubility can be maintained after the removal of the denaturing agent, particularly if the protein can be folded into its native conformation. However, not all proteins refold readily and after the removal of the denaturing agent the proteins will reaggregate and/or precipitate. In the case of Amb a I, the recombinant protein stays in solution at low concentrations but aggregates with itself and other proteins. The recombinant Amb a I is not expressed at high levels and may be toxic to E. coli. Therefore, isolation from a complex mixture of E. coli proteins was necessary. Monoclonal antibodies which recognize the denatured form of Amb a I were available, allowing for immunoaffinity purification. However, because the protein was not monomeric, this chromatographic technique did not provide an improvement in the purity level when run in normal buffer solutions. Analysis of one monoclonal antibody's stability to urea indicated it could tolerate the presence of 2 M urea and recover full activity. Use of this antibody as an immunoaffinity reagent in a column run in 2 M urea, which minimized aggregation of the E. coli produced proteins, gave a high degree of purification of recombinant Amb a I in one step. This illustrates the potential for the use of denaturing and other solubilizing agents in immunoaffinity chromatography of recombinant proteins.

Allergens↗
PubMed1992

Mapping human T cell epitopes on phospholipase A2: the major bee-venom allergen.

Phospholipase A2 (PLA2), the major bee-venom allergen, was purified by gel filtration, inactivated by denaturing, and carboxymethylating its cysteine residues. Peripheral blood mononuclear cells from an individual (HLA-DR2 [15], Dw52, DQ1 and DQ3) allergic to bee stings were used to generate cell lines specific for PLA2 and a control antigen, tetanus toxoid. These lines were 90% CD3+, 64% CD4+ and 20% CD8+ by fluorocytometry analysis. T-lymphocyte epitope mapping done with 12 overlapping synthetic peptides of PLA2 revealed two immunodominant epitopes. These epitopes correspond to amino acid sequences 50 to 69 and 83 to 97 of PLA2. Cytokine interleukin-4 and Interferon-gamma secretion was studied from PLA2- and tetanus toxoid-specific cell lines. Interleukin-4 secretion was common to both cell lines but only tetanus-toxoid cell lines secreted interferon-gamma. No interferon-gamma was found to be secreted by PLA2-specific cell line in response to stimulation by PLA2 or the two immunodominant peptides.

Allergens↗
PubMed1992

Nonthrombocytopenic purpura associated sequentially with nifedipine and diltiazem.

OBJECTIVE: To report the case of a patient who developed nonthrombocytopenic purpura sequentially following the administration of nifedipine and diltiazem. DATA SOURCES: Case reports, MEDLINE review of pertinent literature, and review of relevant studies. DATA EXTRACTION: Data were extracted from direct patient observation and review of laboratory studies and published reports. DATA SYNTHESIS: Nonthrombocytopenic purpura secondary to cutaneous vasculitis is a known, although rare, adverse effect of nifedipine. It has not been reported in association with diltiazem. We report the case of a 75-year-old woman in whom a purpuric rash demonstrated by biopsy to be attributable to cutaneous vasculitis developed in the course of nifedipine therapy. The rash disappeared after discontinuation of the drug; however, it recurred when diltiazem therapy was initiated. CONCLUSIONS: Nonthrombocytopenic purpura may be associated with diltiazem as well as with nifedipine. When this adverse effect occurs following administration of a calcium-channel blocker, caution is advised in using other agents of the same class.

Aged↗
PubMed1991

Epidemiology of swine toxoplasmosis in Taiwan.

From July 1987 to June 1988, serum samples from 3,880 pigs from eight geographic locations in Taiwan were examined for Toxoplasma gondii antibodies using the latex agglutination test (LA test) and IgM-enzyme-linked immunosorbent assay (IgM-ELISA). A total of 1,073 samples (27.65%) were positive by the LA test. The percentage of positive reactions varied by location as follows: Taoyuan 44.44% (128/288), Taichung 27.60% (183/663), Tainan 22.28% (119/534), Kaohsiung 19.60% (98/500), Pingtung 17.92% (86/480), Hualien 33.95% (163/480), Ilan 31.66% (152/480), Taitung 31.64% (144/455). In the IgM-ELISA 1,828 of 3,880 samples (47.11%) were positive and the distribution of positive reactions were: Taoyuan 59.02% (170/288), Taichung 53.69% (356/663), Tainan 52.24% (279/534), Kaohsiung 54.60% (273/500), Pingtung 18.95% (91/480), Ilan 47.50% (228/480), Hualien 42.70% (205/480), Taitung 49.67% (226/455). On one farm, 20 of 120 sows experienced abortion and stillbirths due to Toxoplasma gondii. Lesions and T. gondii were found in lungs, liver, kidneys, heart, and placenta of one of the aborted fetuses.

Abortion, Veterinary↗
PubMed1983

Isolation of serologically active HLA-A, B, C and DR antigens as monitored by a fixed cell radioimmunoassay.

Procedures for isolation of antigenically active preparations of human HLA antigens were monitored using a sensitive and quantitative radioimmunoassay for HLA-A, B, C or HLA-DR antigens. These assays involve binding of radiolabeled monoclonal antibodies to appropriate target cells and inhibition of this binding by solubilized antigen preparations. Fixation of the target cells with glutaraldehyde allows quantitation of inhibitors in high concentrations of nonionic detergents. Using this assay, it was possible to examine quantitatively the relative merits of several alternative procedures for isolating both class I and class II antigens. For example, chromatography of cell lysates on columns of Ricinus communis agglutinin gave high recoveries of DR antigens purified from the majority of cell proteins. When Lens culinaris hemagglutinin was used for separation of cell lysates approximately 90% of the A, B, C antigens but only 32% of the DR antigens bound the column and were eluted by alpha-methyl-mannoside. Immunoadsorbent column were then used to recover antigenically active molecules suitable for structural or functional studies from these enriched fractions.

Antibodies, Monoclonal↗
PubMed1979

Simplification and spin-spin analysis of the side chain proton magnetic resonance spectrum of the decapeptide gramicidin S using difference scalar decoupling and biosynthesis of specifically deuterated analogs.

Biosynthesis of specifically deuterated molecules and difference scalar decoupling permitted an analysis of all C alpha-C beta spin systems of gramicidin S. Proof is presented that proton magnetic resonance spectra obtained by difference scalar decoupling yield not only spectral assignments and simplification but also accurate chemicals shifts and scalar coupling constants. The variations in (3J alpha beta) and in proton chemical shifts at temperatures over the range of -54 degrees -+66 degrees C are consistent with the internal rotation around the C alpha-C beta bonds of Val1, Orn2, Leu3, and Phe4 residues discovered using carbon 13 spectroscopy. The value (3J alpha beta) = 1.5 Hz for the proline residue is consistent with there being only one C alpha-C beta conformer. This is supported by the small temperature dependence of (3J alpha beta). However, it cannot be rigorously excluded that oscillation between a major and a minor C alpha-C beta conformation occurs for proline.

Amino Acids↗
PubMed1979

Multiple solution conformations and internal rotations of the decapeptide gramicidin S.

The conformations of every C alpha H-C beta H2 moiety of the peptide gramicidin S are reported. Internal rotation occurs, but distinct preferences for one side chain rotamer, greater than 80%, are found for the D-phenylalanine and ornithine residues. Leucine and valine exhibit more extensive averaging while proline is shown to be at least 90% in the Ramachandran B conformation. The data are consistent with the coexistence of many tertiary conformations of gramicidin S; the statistical weights of the twelve major tertiary conformations consistent with the rotamer populations are reported. The relative statistical weights of the tertiary conformers depend upon temperature and solvent. A comparison of the conclusions from this publication and conformations derived by energy minimization procedures is made. Partial agreement was found, but the calculations have not yet predicted the wealth of coexisting tertiary conformations nor accounted for the subtle effects of solvent. It is proposed that a more complete picture of the conformational dynamics of gramicidin S and other peptides will result from calculations which use as a basis the extensive data reported here.

Amino Acids↗
PubMed1979

Total assignments, including four aromatic residues, and sequence confirmation of the decapeptide tyrocidine A using difference double resonance. Qualitative nuclear overhauser effect criteria for beta turn and antiparallel beta-pleated sheet conformations.

The complete assignments of all the proton magnetic resonance signals from each NH-CalphaH-CbetaH2 moiety in a complex peptide containing several residues of the same type has not yet been achieved without specific or stereospecific isotopic enrichment. We report the sequencing and proton magnetic resonance spectral assignments, including those of 4 aromatic residues, of tyrocidine A, an analog of the decapeptide gramicidin S. Two complementary methods, proton-proton nuclear Overhauser enhancements and scalar decoupling, evaluated by two distinct forms of difference double resonance, were used. All chemical shifts, scalar coupling constants, and [1H:1H] nuclear Overhauser enhancements for the backbone protons are reported. The [1H:1H] nuclear Overhauser enhancements are consistent with tyrocidine A possessing a beta-I turn/beta-II' turn/antiparallel beta-pleated sheet conformation. In addition to the previously proposed nuclear Overhauser enhancement criteria for beta turns and antiparallel beta sheets, another criterion for identifying the antiparallel beta sheet is demonstrated; namely, the nuclear Overhauser enhancement between 2 CalphaH protons of the central resisdues, in this case the Phe7CalphaH and Orn2CalphaH.

Amino Acid Sequence↗
PubMed1979

Inhibition of carboxypeptidase A catalyzed peptide hydrolysis by 3-phenylpropanoate at activating and nonactivating substrate concentrations.

The carboxypeptidase A catalyzed hydrolyses of five structurally related dipeptide substrates in the presence of the inhibitor 3-phenylpropanoate have been studied. At nonactivating substrate concentrations, 3-phenylpropanoate is a mixed inhibitor of carbobenzoxyglycyl-L-phenylalanine hydrolysis and a noncompetitive inhibitor of the hydrolyses of benzoylglycyl-L-phenylalanine, cinnamoylglycyl-L-phenylalanine, hydrocinnamoylglycyl-L-phenylalanine, and acetylglycyl-L-phenylalanine. When carbobenzoxyglycyl-L-phenylalanine and benzoylglycyl-L-phenylalanine exhibit substrate activation, inhibition by 3-phenylpropanoate is mixed but appears to be mostly competitive. Proposed here is a site for the binding of 3-phenylpropanoate along with a kinetic mechanism consistent with these data.

Carboxypeptidases↗
PubMed1972

Distribution of Necator americanus and Ancylostoma duodenale in Liberia.

In the first country-wide survey of hookworm infection in Liberia, diagnosis by test-tube filter-paper cultivation revealed a prevalence of more than 90%. This sensitive technique also permitted differential species determination. Necator americanus was found to occur in all regions and in a high proportion of the persons examined. Ancylostoma duodenale was mainly confined to a narrow coastal belt, and usually parasitized individuals harbouring N. americanus as well. The average number of eggs per gram of faeces (EPG) of infected individuals was lowest in the population of the hinterland. During the latter part of the studies a modified test-tube filter-paper cultivation technique was used in combination with dilution counting to obtain data on intensity of infection separately for the 2 species. For N. americanus there was little regional difference in the intensity of infection, but the EPG for A. duodenale was much higher in people living in the coastal area.

Adolescent↗
PubMedDate not supplied

Chromatographic properties of denatured skin and bone collagens on hydroxyapatite.

Denatured collagen samples extracted from the skin and bone of lathyritic rats with guanidine hydrochloride were chromatographed on hydroxyapatite columns. A major fraction of the bone extract that was rich in alpha chain showed a stronger binding to hydroxyapatite when compared to the corresponding fraction from skin. Thus, bone collagen shows a special affinity for hydroxyapatite after isolation and denaturation.

Amino Acids↗