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Biomedical subjects

K Huang

Publications and source records attributed to K Huang.

At least 145 records · Page 8Linked to original sources
PubMed1994

Interference by complex structures of target DNA with specific PCR amplification.

It has been considered that target DNA is a forgiving component for PCR amplification. Herein we present evidence to demonstrate that secondary structure located at the end of a template may interfere with the specificity of amplification. Experiments indicate that nonspecific amplification results from a long stretch of stem and loop structures at the 3' end of prochymosin cDNA. Based on the sequence of mRNA coding for prochymosin, it is argued that the sequence responsible for the formation of the complex structure described here is most likely generated during synthesis of the second cDNA strand.

Base Sequence↗
PubMed1994

Myelin localization of a central nervous system ligand for L-selectin.

L-selectin is a lectin-like receptor involved in lymphocyte attachment to lymph node high endothelial venules (HEV). Previously, we showed that L-selectin also participates in the in vitro attachment of lymphocytes to central nervous system (CNS) white matter. Use of an L-selectin chimera demonstrated ligand sites within CNS white matter but not the peripheral nervous system (PNS). Now employing higher resolution mapping, including EM cytochemistry, we localize the ligands to the actual myelin sheaths of CNS neurons. In the shiverer mouse, which lacks compact myelin, ligands are greatly diminished. Comparison of the myelin-associated ligand with the previously characterized HEV-ligands demonstrates a number of differences.

Animals↗
PubMed1994

Dipeptidyl peptidase IV from porcine seminal plasma: purification, characterization, and N-terminal amino acid sequence.

Dipeptidyl peptidase IV (DPP IV) was purified to homogeneity from porcine seminal plasma by polyacrylamide gel electrophoresis (PAGE). The molecular weight of the purified enzyme was calculated to be approximately 290,000 on PAGE in the absence of sodium dodecyl sulfate (SDS) and 310,000 on Sephacryl S-300 HR column chromatography, and to be 115,000 and 105,000 on SDS-PAGE in the absence and presence of beta-mercaptoethanol. The enzyme is suggested to be composed of three identical subunits. The enzyme rapidly hydrolyzed the substrate Gly-Pro-MCA, and weakly the substrate Lys-Ala-MCA. It was strongly inhibited by diisopropylphosphofluoridate (DFP), and moderately by both phenylmethyl-sulfonyl fluoride (PMSF) and 4-(2-aminoethyl)-benzenesulfonyl fluoride (AEBSF). It was also strongly inhibited by zinc ion. The amino acid sequence of the first 18 residues of the enzyme was Asn-Lys-Gly-Thr-Asp-Asp-Ala-Ala-Ala-Asp-Ser-Arg-Arg- Thr-Tyr-Thr-Leu-Thr-. This sequence was highly homologous to the sequences in the rear of the transmembrane site of human and rat liver DPP IVs and mouse thymus DPP IV. The native DPP IV is suggested to be released into the seminal plasma after the cleavage of the hydrophobic N-terminal domain by chymotrypsin-like or pepsin-like enzymes. Other properties of DPP IV including kinetic parameters, pH stability and heat stability were characterized.

Amino Acid Sequence↗
PubMed1994

A recombinant amino-terminal fragment of bactericidal/permeability increasing protein (rBPI23) inhibits soluble CD14-mediated lipopolysaccharide-induced endothelial adherence for human neutrophils.

Exposure of cultured human umbilical vein endothelial cells (HUVEC) to lipopolysaccharide (LPS) or interleukin 1 (IL-1) causes increased expression of adhesion molecules such as E-selectin and CD54 by HUVEC and consequently increased adherence of peripheral blood neutrophils. A recombinant aminoterminal fragment of bactericidal/permeability increasing protein (rBPI23) was shown to specifically block the LPS-induced adhesiveness of HUVEC for neutrophils. rBPI23 also prevented the LPS- but not IL-1 beta-induced upregulation on HUVEC of E-selectin and CD54. Furthermore, this inhibition was evident even when the endothelial cells were exposed to LPS for up to 1-2 h prior to rBPI23 addition. The inhibitory effects of an anti-CD14 monoclonal antibodies (mAb) were similar to those of rBPI23. Combination of the anti-CD14 mAb and rBPI23 resulted inhibition greater than either one used alone. These studies demonstrate that rBPI23 acts as a specific and potent inhibitor of soluble CD14-mediated LPS induction.

Antibodies, Monoclonal↗
PubMed1992

Functional implication of disulfide bond, Cys250 -Cys283, in bovine chymosin.

The reduction, carboxymethylation and mercuration of disulfide bond, Cys250-Cys283, located on the surface of bovine chymosin molecule resulted in the loss of about 25% of enzyme activity, suggesting that Cys250-Cys283 is not intimately involved in catalytic mechanism. Cys250 and Cys283 were substituted with Asp. and Ser. by site- directed mutagenesis of the structural gene coding for bovine prochymosin B. All three mutants (C250D/C283S, C250D, C283S) failed to be activated to chymosin in acid, indicating that Cys250-Cys283 might have some contribution to the correct refolding of the unfolded prochymosin.

Animals↗
PubMed1992

Crystallization and preliminary X-ray diffraction studies of two mutants of lactate dehydrogenase from Bacillus stearothermophilus.

Bacillus stearothermophilus lactate dehydrogenase, one of the most thermostable bacterial enzymes known, has had its three-dimensional structure solved, the gene coding for it has been cloned, and the protein can be readily overexpressed. Two mutants of the enzyme have been prepared. In one, Arg171 was changed to Trp (R171W) and Gln102 was changed to Arg (Q102R). In the other, the mutation Q102R was maintained, but Arg171 was changed to Tyr (R171Y). In addition, an inadvertent C97G mutant was present. Both mutants have been crystallized by the hanging drop vapor diffusion method at room temperature. Bipyrimidal crystals have been obtained against (NH4)2SO4 in 50 mM piperazine HCl buffer. The crystals belong to space group P6(2)22 (P6(4)22) (whereas the native enzyme, the structure of which has been solved by Piontek et al., Proteins 7:74-92, 1990) crystallized in the space group P6(1)) with a = 102.3 A, c = 168.6 A for the R171W, Q102R, C97G triple mutant, and a = 98.2 A; c = 162.1 A for the R171Y, Q102R, C97G mutant. These crystal forms appear to contain one-quarter of a tetramer (M(r) 135,000) in the asymmetric unit and have VM values of 3.8 and 3.3 A3/dalton, respectively). The R171W mutant diffracts to 2.5 A and the R171 Y mutant to approximately 3.5 A.

Bacterial Proteins↗
PubMed1992

Premarital sexual behavior among Chinese college students in the United States.

Little is known about sexuality among Chinese in the U.S. There are reasons to believe that their sexual attitudes and behaviors would differ from those of Chinese in Asia as well as other groups in the U.S. This survey of ethnic Chinese college students in the U.S. examined the permissiveness of their attitudes toward premarital sex and their premarital sexual behavior with an eye toward their levels of acculturation. Over 60% approved of premarital sexual intercourse when the partners were in love or engaged. There was no significant gender difference in sexual permissiveness. Most of the men and women had engaged in kissing, necking, and petting, but most had not engaged in sexual intercourse. Gender differences were found in sexual experience: Chinese men were less experienced than Chinese women. Sexual permissiveness and experience were related to level of acculturation. Those who dated only Caucasians were more sexually experienced than those who dated only Chinese. Results are discussed in terms of differences in sexual attitudes and behaviors between Caucasian Americans and Chinese Americans and in terms of acculturation.

Acculturation↗
PubMed1992

Hospital boarder babies and their families: an exploratory study.

Data were abstracted from the medical and social work charts of 20 newborns who were classified as boarder babies and their mothers (N = 18) to identify bio-psycho-social factors associated with boarding. The findings show that the mothers whose newborns remained in the hospital as boarders were usually drug users, had other children in out-of-home placement, and over half are periodically homeless. Most of these mothers also lacked informal social support. The major health problems of infants were prematurity and associated infections. The total number of infant boarding days was 195 for a total of $117,000 in unreimbursed costs to the hospital. Practice and program implications and directions for future research are discussed.

Adult↗
PubMed1992

[Observations on the changes in plasma pH and kalium content and the effect of acupuncture on them in the rats with hemorrhagic shock].

In the present work, the changes of pH and the kalium content of blood and the effects of acupuncturing "Renzhong" on these changes were observed in rats with hemorrhagic shock. The experimental rats were randomly divided into three groups: surgical control group, shocked control group, shocked acupuncture group. The blood pH was significantly decreased at maintaining shock for one hour (n = 30), P < 0.01; there was no change in surgical control group (n = 15), pH decreased continually with the shock time, (n = 14). But pH tended to going up again after acupuncturing "Renzhong" for 15 min (n = 16). The content of blood kalium was increased at maintainually shock for one hour (n = 26). The content of blood kalium was significantly increased with the prolonging shocked time (n = 12) or acupuncturing "Renzhong" (n = 14), P < 0.05. But there was no clear change in surgical group (n = 15). The results suggested that the acidosis condition was slightly rectified by acupuncture via modulating the respiratory function and reducing the acidic metabolites in blood of the rat with hemorrhagic shock. But the hyperkalemia produced by shock was hardly rectified by acupuncture.

Acupuncture Therapy↗