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Biomedical subjects

H L Yang

Publications and source records attributed to H L Yang.

At least 55 records · Page 3Linked to original sources
PubMed1992

[Clinical observation on efficacy of ivermectin in the treatment of intestinal nematode infections].

A total of 166 cases were divided into 3 groups: group A comprised 55, group B 54 and group C 57 cases. Group A received ivermectin 0.1 mg/kg orally at a single dose, the cure rates were 100%, 3.8% and 50% for ascaris, hookworm and trichuris, infections respectively: group B received ivermectin 0.2 mg/kg orally at a single dose, the corresponding cure rates were 95.5%, 11.8% and 76.5% respectively; group C received pyrantel pamoate 10 mg/kg orally at a single dose, the corresponding cure rates were 95.5%, 29.6% and 31.6% respectively. Although the cure rates were very low for hookworm infection in both group A and B, however, a number of adult worms of Ancylostoma duodenale and Necator americanus were expelled aster medication; It indicates that ivermectin has some effects on these two species of human hookworm. Side effects were mild and transient in all groups.

Adolescent↗
PubMed1992

[Sensitivity in vitro of Plasmodium falciparum to chloroquine, pyronaridine, artesunate and piperaquine in south Yunnan].

The sensitivity of P. falciparum to chloroquine, pyronaridine, artesunate and piperaquine (CQ, PD, AT, PQ) was assayed using in vitro microtechnique in south Yunnan in 1990. The resistance rates were 98.7% (75/76), 27.6% (16/58), 13.8% (9/65) and 97.7% (43/44) respectively, and ID50 were 125.0, 19.0, 4.7 and 243.3 nmol/L, respectively. The resistance rate against CQ showed no change as compared to the rates against CQ 5 and 9 years ago; but the ID50 was lower. CQ-resistant P. falciparum showed a marked cross-resistance to PQ, but not to PD and AT. AT-resistant P. falciparum exhibited cross-resistance to the above-mentioned three drugs. PD-resistant P. falciparum showed no cross resistance to AT, but showed cross resistance to CQ and PQ. In comparison with chloroquine-coated plates, the plates coated with pyronaridine, artesunate or piperaquine gave similar results as the former, which were shown by the rise in schizont inhibition rates along with the rise in drug concentration. It indicates that pyronaridine-, artesunate-, and piperaquine-coated plates can be used in the assay of sensitivity of P. falciparum to the three drugs.

Animals↗
PubMed1991

A multisectoral approach to primary health care in Fujian, China.

The government of Yongan in Fujian province has developed a multisectoral primary health care program in the rural community of Dahu with the aim of reaching "Health for All" by 1993. In keeping with the spirit of the Alma Ata declaration and the tradition of local self-reliance in China, the program has involved the entire community and is financed almost exclusively at the local level. Community leaders were trained in the importance of primary health care so that they could serve as role models. The project includes school health education, domestic hygiene education, reconstruction of homes to separate the kitchen, toilet and animals pens, road construction to eliminate dust, environmental sanitation, occupational health, and the upgrading of health care facilities. A number of local ordinances regarding construction, zoning and smoking have also been instituted. The results of the project's first year of implementation in two villages indicate that construction of the new road is near completion, and access to clean water is almost universal. Gains are also reported in the percentage of the population receiving physical examinations, the number of health stations that now meet state standards, and the number of homes that are constructed according to the new guidelines.

China↗
PubMed1991

Inhibitory property characterization and reactive site exploration of the arrowhead proteinase inhibitor.

Affinity chromatography was used to separate two components A and B of the crystalline arrowhead proteinase inhibitor. Both A and B are double-headed and multifunctional proteinase inhibitors. Inhibitor A is capable of inhibiting equimolarly trypsin and chymotrypsin simultaneously, and has a weak inhibitory activity toward kallikrein; whereas inhibitor B can inhibit two molecules of trypsin simultaneously, and shows rather higher inhibitory activity toward kallikrein than inhibitor A, but its inhibitory activity toward chymotrypsin is much weaker than that of inhibitor A. The results of chemical modification and the competitive binding of trypsin and chymotrypsin with inhibitor A showed that the two reactive sites of both inhibitors A and B are Lys and Arg residues. Among them the Lys reactive site is specific for inhibiting mainly trypsin, whereas the active domain composed of the Arg reactive site appears to be multifunctional and capable of inhibiting many different Ser proteinases. Based on the structural characteristics of inhibitors A and B, it was predicated that the two reactive sites should be located in the positions Lys-Ser (44-45) and Arg-Tyr-Lys (76-78), respectively. In inhibitor A, there exists another hydrophobic residue involved in inhibiting chymotrypsin. This residue might be situated in the reactive region composed of the Arg reactive site.

Chymotrypsin↗
PubMed1990

Reliability of ultrasonography in diagnosis of biliary lithiasis.

Preoperative B-mode ultrasonograms of the biliary system in 302 patients with cholelithiasis confirmed operatively between March 1981 and December 1986 were analyzed retrospectively in contrast to the operative findings. The results showed that during 1985-1986 the sensitivity of ultrasonography (US) to detect stones in gallbladder (GB), extrahepatic bile duct (EHD) and intrahepatic bile duct (IHD) was 98.4%, 68.2% and 82.4% respectively, each was much higher than its counterpart during the periods 1981-1982 and 1983-1984 (P less than 0.01). The specificity of US in detecting GB, EHD and IHD stones was all over 90% during the latter two years. The observations made in the present study suggest that the accuracy of US has risen so significantly that it should be used as the first modality in diagnosing cholelithiasis, particularly cholecystolithiasis. It, however, should be supplemented with such tests as oral cholecystography, intravenous cholangiography, percutaneous transhepatic cholangiography (PTC), endoscopic retrograde cholangiopancreatography (ERCP) to establish a correct diagnosis when its interpretation is equivocal.

Bile Duct Diseases↗
PubMed1989

Evidence for the overestimation of molecular masses of proteins after chemical modification and chemical crosslinks on sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE).

Human trypsin inhibitor (home prepared), lactalbumin, trypsinogen, carbonic anhydrase, and bovine serum albumin were submitted to succinylation and their molecular masses were determined by SDS-PAGE according to the method of Weber and Osborn (1969 J. Biol. Chem. 244, 4406) before and after chemical modification. High estimates of their molecular masses were obtained. The monomer and dimer of arrowhead inhibitor proteinase-B (Chinese vegetable legume) obtained after chemical crosslink(s) were also submitted to SDS-PAGE and their apparent molecular masses were also determined and compared to the native arrowhead inhibitor proteinase-B. Abnormally high estimates of their molecular masses were obtained. Our results agree with those in the literature.

Carbon Radioisotopes↗
PubMed1989

Isolation of a species-specific DNA probe for Neisseria gonorrhoeae using a novel technique particularly suitable for use with closely related species displaying high levels of DNA homology.

The use of nucleic acid probes has become an increasingly common method for detecting pathogenic micro-organisms in clinical specimens. In the course of our efforts to isolate species-specific DNA probes for bacterial pathogens, we encountered a special problem with regard to Neisseria gonorrhoeae. As a consequence of the high degree of DNA homology that this organism displays with its nearest relative, Neisseria meningitidis, the isolation of such probes could not be readily achieved. We therefore developed a novel method of probe isolation which overcomes this problem. This methodology relies upon the application of a 'sandwich' hybridization assay to screen an M13 'shotgun' library derived from N. gonorrhoeae genomic DNA. For this, genomic DNA from N. gonorrhoeae and N. meningitidis was immobilized on nitrocellulose filters and probed with recombinant phage DNA from candidate clones. Those clones which had hybridized to target sequences were then detected using labelled vector sequences in a second hybridization step. By this means we obtained a numerical assessment of the degree of specificity of candidate clones for the target organism as compared to one or more related species. Using this technique we have isolated three DNA probes which are highly specific for N. gonorrhoeae and which display no cross-reactivity with N. meningitidis or other members of the Neisseriaceae. This paper presents the basis of the methodology and describes the isolation and characterization of three N. gonorrhoeae-like specific probes.

Cloning, Molecular↗
PubMed1988

Speciation of organisms within the Mycobacterium avium-Mycobacterium intracellulare-Mycobacterium scrofulaceum (MAIS) complex based on restriction fragment length polymorphisms.

A DNA probe which hybridizes to all pathogenic species of slow-growing mycobacteria has been used to identify restriction-fragment-length-polymorphisms (RFLPs) in Bam Hl digests of chromosomal DNA from members of the Mycobacterium avium-Mycobacterium intracellulare-Mycobacterium scrofulaceum complex. The RFLP patterns so produced were found to fall into distinct categories which were representative of each of the three species. Except for two doubtful isolates, strains of M. avium were found to fall into two related RFLP-types, one of which contained the vast majority of the strains tested. In contrast, M. intracellulare strains were found to be more heterogeneous. For these strains, we found one major RFLP-type and one subsidiary type which appears to be a sub-set of the first. We also found two further RFLP-types which contained serovars 7 and 18 respectively. We conclude from this that M. avium, M. intracellulare and M. scrofulaceum are three distinct species and that serovars belonging to the 'intermediate group' of Meissner and Anz belong to the species M. avium. Utilizing these criteria, we examined a number of isolates from the 'ambiguous' serovar 9 and found that of eight strains tested, six typed as M. avium and two typed as M. intracellulare.

Acquired Immunodeficiency Syndrome↗
PubMed1988

DNA probes for mycobacteria. I. Isolation of DNA probes for the identification of Mycobacterium tuberculosis complex and for mycobacteria other than tuberculosis (MOTT).

Traditional methods used in identifying mycobacteria such as acid-fast bacillus stains and culture are often time-consuming, insensitive and non-specific. The isolation of DNA probes, coupled to a non-radioactive, e.g. biotin-based detection system, have the potential to foster the development of clinical assays for Mycobacterium tuberculosis and mycobacteria other than tuberculosis (MOTT) that are rapid, sensitive and specific. To this end, we have isolated two different probes: one which is specific for the Mtb complex and one which recognizes all other potentially pathogenic mycobacteria. The use of these probes in combination should allow the detection and differentiation of M. tuberculosis from MOTT. To isolate the first probe, we prepared a library of M. tuberculosis DNA fragments in a lambda EMBL phage vector. Recombinant phage were screened by plaque-lift hybridization procedures using nick-translated mycobacterial genomic DNA to identify sequences specific to the Mtb complex. Inserts from candidate recombinant phage were purified, nick-translated and hybridized against a wide variety of filter-bound mycobacterial and non-mycobacterial DNAs. Two clones were identified which hybridized to the closely related M. tuberculosis, M. bovis and M. microti but not to other species of mycobacteria. The second probe was isolated by preparing a library of M. malmoense DNA fragments in lambda EMBL and screening by plaque-lift hybridization. One clone was identified which, in addition to recognizing members of the Mtb complex, also hybridized to M. intracellulare, M. malmoense, M. scrofulaceum, M. simiae, M. xenopi, M. avium, M. szulgai, M. kansasii and M. haemophilum. None of the three clones hybridized to DNA from non-mycobacterial species.

Animals↗
PubMed1988

On the substrate specificity of cytochrome P450IIIA1.

The instability of the solubilized/purified form, the lack of catalytic activity of the stabilized, macrolide-complexed form, and the compromised catalytic activity of the decomplexed form of steroid-inducible cytochrome P450IIIA1 motivated further investigations of the substrate specificity of this isozyme. A major complementary goal was to identify reactions utilizable as sensitive, specific diagnostic probes for the detection and partial characterization of this isozyme in tissues for which isolation and purification are not practical (e.g., extrahepatic, embryonic tissues, etc.). The approach utilized a combination of a specific, purified inducer, specific inhibitors including triacetyloleandomycin and inhibitory antibodies, and diagnostic probe substrates including the phenoxazone ethers, testosterone, warfarin, 2-acetylaminofluorene, estradiol-17 beta and benzo[a]pyrene. The results obtained indicated that steroid-inducible, rat hepatic P450IIIA1 would catalyze minimal or no O-dealkylation of methoxy-, ethoxy- or pentoxyphenoxazone but catalyzed rapid O-debenzylation of benzyloxyphenoxazone. Hydroxylation of testosterone was specific for the beta face of the molecule at the 2-, 6-, 15- and 16-positions with no detectable conversion to androstenedione and minimal hydroxylation on the alpha face. Both the R- and S-enantiomers of warfarin were attacked at positions 9 and 10, and these reactions appeared to be specific to isozymes of the IIIA family. Aromatic hydroxylation of estradiol-17 beta was efficiently catalyzed, particularly at the 2-position. Hydroxylations of 2-acetylaminofluorene at positions 5 and 7 were catalyzed at relatively rapid rates, but N-hydroxylation of the same substrate was not catalyzed effectively. Hydroxylation of benzo[a]pyrene occurred preferentially at carbon 3 with much lesser activity at carbon 9 and little or no detectable attack at positions 7 or 1. The results indicated that the 2 beta- and 15 beta-hydroxylation of testosterone and the 10-hydroxylation of warfarin would serve as the most useful probes thus far available for detection of the presence of functional P450IIIA1 isozymes in tissues for which isolation and purification are impractical. The results also indicated a very broad, yet selective substrate specificity for the steroid-inducible P450IIIA1.

2-Acetylaminofluorene↗
PubMed1988

Simultaneously occurring condylomata acuminata, carcinoma in situ and verrucous carcinoma of the vulva and carcinoma in situ of the cervix in a young woman. A case report.

A case of simultaneously occurring condylomata acuminata, carcinoma in situ and verrucous carcinoma of the vulva and carcinoma in situ of the cervix was seen in a 26-year-old woman. In situ DNA hybridization on sections of the condyloma acuminata and verrucous carcinoma yielded DNA sequences for human papillomavirus 6.

Adult↗
PubMed1987

Molecular cloning of a species-specific DNA probe for Campylobacter jejuni.

Conventional procedures for isolating and identifying Campylobacter jejuni are cumbersome and time-consuming. A simpler approach would be to use DNA probes to identify these organisms. To obtain such probes we cloned chromosomal DNA from C. jejuni into the lambda replacement vector EMBL 4. Recombinant phages were screened for C. jejuni-specific inserts by DNA hybridization using chromosomal DNA from either C. jejuni or C. coli which had been radioactively labelled with 32P. By this means, recombinant phages were identified which hybridized to C. jejuni but not to C. coli DNA. These phages were then subjected to further screening using DNA from other Campylobacter species. Three DNA fragments were identified which hybridized to DNA from eight ATCC (American Type Culture Collection) strains of C. jejuni but not to DNA from C. coli, C. laridis, C. fetus or a variety of other bacterial species. These DNA fragments are suitable for use as specific probes in DNA-based diagnostic tests for C. jejuni infections.

Campylobacter↗