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Biomedical subjects

S H Yu

Publications and source records attributed to S H Yu.

At least 37 records · Page 2Linked to original sources
PubMed1997

Nucleotide sequence variations in the internal ribosome entry site of hepatitis C virus-1b: no association with efficacy of interferon therapy or serum HCV-RNA levels.

The extreme 5'-proximal sequences of the hepatitis C virus (HCV) genome including the 5'untranslated region (5'UTR) and the first 30 nucleotides of the core region are highly conserved, and serve as an internal ribosome entry site (IRES) that initiates the cap-independent translation of HCV polyprotein. Mutations in the IRES sequence have been shown to cause changes in the efficiency of protein translation in vitro. However, the significance of genetic variations in the IRES is not fully known in clinical settings. Pretreatment sera of 25 patients with HCV-1b infection who were treated with interferon were amplified by polymerase chain reaction (PCR), and the IRES sequence was directly sequenced. Correlation of interferon responses or other clinical features with IRES sequence variability was studied. Eleven of 25 patients were sustained responders (SR) of interferon treatment (negative serum HCV RNA and normal alanine transaminase levels for 6 months after the end of interferon treatment), and the other 14 patients were nonresponders ([NR], defined as any patient with positive serum HCV RNA within 6 months after the end of interferon therapy). In each patient, one to four nucleotide substitutions were found compared with the consensus sequence of HCV-1b genotype. There were no differences in the number of nucleotide substitutions between either SR and NR (mean, 1.8 in SR, 2.1 in NR; P = .30), and no specific variations associated with SR or NR were observed. Although NR had significantly higher serum levels of pretreatment HCV RNA than SR (median, 16 vs. <0.5 Meq/mL; P = .02), there was no correlation between the HCV-RNA level and the number of nucleotide substitutions in the IRES (mean, 1.9 nucleotide substitutions in 12 patients with HCV RNA <0.5 Meq/ mL vs. 2.1 nucleotide substitutions in 13 patients with HCV RNA >0.5 Meq/mL; P = .61). Sequence variability of the IRES has no influence on interferon efficacy or serum HCV-RNA concentrations in patients with chronic HCV-1b infection.

Adult↗
PubMed1997

9-Hydroxycrisamicin A, a new cytotoxic isochromanquinone antibiotic produced by Micromonospora sp. SA246.

9-Hydroxycrisamicin A, a new cytotoxic isochromanquinone antibiotic, was isolated from a soil microorganism SA246 which was identified as Micromonospora sp. The molecular formula of 9-hydroxycrisamicin A was determined as C32H22O13 based on the HRFAB-MS analysis, and the structure was determined by various NMR experiments. 9-Hydroxycrisamicin A showed weak antimicrobial activity against Gram-positive bacteria and strong cytotoxic activity against some human cancer cell lines such as SK-OV-3 (ovarian), HCT15 (colon), SK-MEL-2 (melanoma), A549 (lung), XF498 (central nervous system) with ED50 of 0.47-0.65 microgram/ml.

Anti-Bacterial Agents↗
PubMed1996

Effect of pulmonary surfactant protein A and neutral lipid on accretion and organization of dipalmitoylphosphatidylcholine in surface films.

The effects of surfactant-associated protein A (SP-A) on lipid adsorption to the air-water interface and accumulation of dipalmitoylphosphatidylcholine (DPPC) in the surface region were investigated at 37 degrees C. Dispersions used were bovine pulmonary lipid extract surfactant with or without neutral lipid (NL). Lipid adsorption was examined with the Wilhelmy plate technique and DPPC accumulation by monitoring surface radioactivity from [14C]DPPC with a scintillation probe. SP-A enhanced the rate of lipid adsorption, while both SP-A and NL increased the extent of DPPC accumulation. At the specific radioactivity used [14C]DPPC monolayers were undetectable: the surface radioactivity arose from surface-associated DPPC beneath the monolayer. At the highest concentration studied (0.3 mg lipid/ml), NL greatly enhanced DPPC accumulation and SP-A attenuated this effect. Langmuir-Blodgett (L-B) films were prepared from [14C]DPPC-labeled dispersions (0.3 mg lipid/ml) at equilibrium surface tension. Autoradiographs of L-B films from lipid extract surfactant exhibited a diffuse misty appearance, while NL promoted formation of heterogeneous DPPC aggregates. Addition of SP-A to lipid extracts without NL generated DPPC aggregates; more uniform larger aggregates appeared in the presence of SP-A and NL. Radiation measurements confirmed that the L-B films were composed of more than monolayers. SP-A did not increase DPPC levels in films deposited from lipid extracts unless NL was present. These results indicate that neutral lipid cooperates with surfactant-associated protein A to organize dipalmitoylphosphatidylcholine in the surface films and enhance formation of a DPPC-rich reservoir below the air-water interface.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1995

Infantile hookworm disease in China. A review.

Hundreds of cases of infantile hookworm disease which shows bloody stools, melena, anorexia, listlessness and oedema, have been reported in China since the 1960s. Hookworm eggs were detected in due course in the faeces of the reported cases. With the exception of a single worm identified as Necator americanus, all the adult worms expelled following chemotherapy or examined at autopsy were Ancylostoma duodenale. Many children showed clinical manifestations and eggs in their faeces on day 1-26 after birth, and more cases occurred within 3 months of birth. Evidently, these infections were mostly transmitted from the mothers by transplacental and/or transmammary routes.

China↗
PubMed1995

Soil-transmitted helminthiases: nationwide survey in China.

A total of 2848 study sites, with about 500 people in each, were randomly sampled for this investigation which covered a total population of 1 477 742. By stool examinations using the Kato-Katz thick-smear and larval-culture techniques, overall prevalences of 47.0%, 18.8%, and 17.2% were obtained for Ascaris lumbricoides, Trichuris trichiura, and hookworm infections, respectively. The number of infections due to Ascaris, Trichuris, and hookworm was estimated as 531 million, 212 million, and 194 million, respectively. Egg counts showed that 75-95% of the subjects had light infections. Higher prevalences of ascariasis and trichuriasis were found in the age group of 5-9, 10-14 and 15-19 years, and among adults for hookworm. Students, farmers (including vegetable growers) and fishermen were the occupational groups with high infection rates. The prevalence of helminthiases was found to be closely associated with climatic and geographical factors. In view of the morbidity and mortality due to these helminthiases, their control, particularly in schoolchildren, is very important.

Adolescent↗
PubMed1994

Effect of pulmonary surfactant protein A (SP-A) and calcium on the adsorption of cholesterol and film stability.

The effect of exogenous cholesterol on the stability of surface films at 37 degrees C from various surfactants was studied with the pulsating bubble surfactometer. Addition of cholesterol (5%, w/w) to bovine lipid extract surfactant (bLES) or mixtures of dipalmitoylphosphatidylcholine/1-palmitoyl-2-oleoyl-phosphatidylglycerol /SP-B (7:3:1%) dispersed in 1.5 mM CaCl2/0.9% NaCl resulted in unstable surface films. Although 10% cholesterol only partially impaired the surface activity of bLES, it virtually abolished that of the reconstituted surfactant. The inhibitory effects of cholesterol were significantly repressed by SP-A (10%, w/w of lipid) and 3 mM CaCl2 or 5 mM CaCl2 without SP-A. Adsorption of cholesterol from various surfactants into the air/water interface was examined by measuring the surface radioactivity of [14C]cholesterol. Cholesterol alone dispersed in 1.5 mM CaCl2/0.9% NaCl could not adsorb to the interface, but it adsorbed readily when mixed with bLES. Cholesterol adsorption was markedly suppressed by SP-A in 3 mM CaCl2/0.9% NaCl or 5 mM CaCl2/0.9% NaCl without SP-A. Electron microscopy revealed striking ultrastructural differences between bLES/5% cholesterol/10% SP-A in 3 mM CaCl2/0.9% NaCl and bLES/5% cholesterol in 3 or 5 mM CaCl2/0.9% NaCl. The former exhibited large multilayer and small unilamellar vesicles, while the latter displayed condensed patches of aggregates. Adsorption studies showed aggregated patches adsorbed more rapidly than vesicles but attained lower equilibrium surface pressures. These results indicate SP-A and calcium limit the adsorption of surfactant cholesterol to the air-water interface.

Adsorption↗
PubMed1994

Nationwide survey of human parasite in China.

A nationwide survey of human parasites in China was conducted during 1988-1992, with a coverage of 30 provinces/autonomous regions/municipalities (P/A/M). A total of 2,848 pilot sites in 726 counties were selected by random sampling, and 1,477,742 individuals residing on were surveyed by fecal examination. The status of paragonimiasis, hydatid diseases, cysticercosis and trichinellosis were summarized through data review. The overall infection rate of intestinal parasites was 62.6% whereas at provincial level, the highest infection rate (94.7%) was recovered in Hainan, and the lowest (17.5%) in Heilong-jiang. A high proportion (43.3%) of polyparasitism among the infected population (882,080) was revealed. Altogether 56 species of parasites comprising protozoa (19), trematode (16), cestodes (8), nematodes (12) and thorny-headed worm (1) were discovered. During the survey a new species and several new records were documented. The number of the population infected with common intestinal parasites was estimated. The diversities of parasite distribution were noted in different nationalities as well as in varied occupations.

Adolescent↗
PubMed1993

Adsorption, compression and stability of surface films from natural, lipid extract and reconstituted pulmonary surfactants.

A pulsating bubble surfactometer was used to study the surface activities and surface film stabilities of bovine pulmonary surfactants (10 mg/ml) and a reconstituted surfactant (10 mg/ml). Pulmonary surfactants were natural surfactant (NS), lipid extract surfactant [LES(chol)] and lipid extract surfactant without neutral lipids (LES). NS is composed of phospholipids, neutral lipids and surfactant-associated proteins (SP-A, SP-B and SP-C). Both LES(chol) and LES are organic solvent extracts of NS. LES(chol) retains all the components of NS except SP-A. Reconstituted surfactant was dipalmitoylphosphatidylcholine (DPPC): 1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG): SP-B/7:3:1%. All three pulmonary surfactants attained the equilibrium surface tension almost instantaneously at 37 degrees C. The adsorption rates of NS and LES(chol) at 24 degrees C were similar to those at 37 degrees C, while LES exhibited a lower adsorption rate at 24 degrees C. Reconstituted surfactant adsorbed slower than any of the pulmonary surfactants. Film stability was studied by recording the spontaneous increase in the pressure gradient of a static bubble at the minimum size (Rmin) once near zero surface tension was attained. The order of surface film stabilities were: reconstituted surfactant > > NS > LES > LES(chol). Surface films of NS and LES could be stabilized by prolonged pulsation, while film stability of LES(chol) was only moderately affected by pulsation. These results indicate that SP-A in NS promotes formation of some unique structure, possibly tubular myelin, which induces selective adsorption of lipids into the surface.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1993

[A preliminary experimental study on processing of peach kernel].

Contents of water, alcohol, ether soluble components and amygdalin of differently processed peach kernel (raw drug, scalded, stir-baked and steamed) were determined. The security of the decoctions from the four processed samples was compared. This paper provides a preliminary experimental basis for the rational utilization of peach kernel.

Amygdalin↗
PubMed1992

Targeted oncogene activation by site-specific recombination in transgenic mice.

An efficient and accurate method for controlled in vivo transgene modulation by site-directed recombination is described. Seven transgenic mouse founder lines were produced carrying the murine lens-specific alpha A-crystallin promoter and the simian virus 40 large tumor-antigen gene sequence, separated by a 1.3-kilobase-pair Stop sequence that contains elements preventing expression of the large tumor-antigen gene and Cre recombinase recognition sites. Progeny from two of these lines were mated with transgenic mice expressing the Cre recombinase under control of either the murine alpha A-crystallin promoter or the human cytomegalovirus promoter. All double-transgenic offspring developed lens tumors. Subsequent analysis confirmed that tumor formation resulted from large tumor-antigen activation via site-specific, Cre-mediated deletion of Stop sequences.

Animals↗
PubMed1992

Effect of pulmonary surfactant protein B (SP-B) and calcium on phospholipid adsorption and squeeze-out of phosphatidylglycerol from binary phospholipid monolayers containing dipalmitoylphosphatidylcholine.

The pulsating bubble technique was used to study the surface activity of binary phospholipid mixtures containing dipalmitoyl-phosphatidylcholine (DPPC) and an unsaturated acidic phospholipid such as egg phosphatidylglycerol (egg PG), 1-palmitoyl-2-oleoyl-PG (POPG) or egg phosphatidic acid (egg PA) in the presence of surfactant-associated protein B (SP-B) and calcium. The relative surface activities were DPPC/egg PG/SP-B (7:3:1%) greater than DPPC/POPG/SP-B (7:3:1%) greater than DPPC/egg PA/SP-B (7:3:1%). The Wilhelmy surface plate technique was utilized to investigate the interaction between pure SP-B in the bulk phase (0.9% NaCl/1.5 mM CaCl2) and preformed DPPC or phosphatidylglycerol (PG) monolayers. Although SP-B injected into the bulk phase reduces the surface tension of a clean surface, no evidence was obtained for the insertion of SP-B into surface monolayers at equilibrium surface tension. Surface radioactivity measurements and the Wilhelmy surface plate technique were also used to study the potential interactions between liposomes of DPPC/POPG (7:3) with or without SP-B and surface monolayers of [14C]DPPC or [14C]POPG. No exchange of phosphatidylcholine (PC) or PG was found between the monolayer and liposomes. We also compared the adsorption of pure POPG or 1-palmitoyl-2-oleoyl- phosphatidylcholine (POPC) and binary mixed liposomes with DPPC in the presence or absence of SP-B and calcium. DPPC/POPG/SP-B (7:3:1%) was found to be more surface active than pure POPG plus 1% SP-B in the presence of calcium. Injection of SP-B into the bulk phase promoted the adsorption of DPPC/POPG liposomes to a greater extent than POPG liposomes. The enhanced adsorption was dependent on the presence of calcium. In contrast to PG, DPPC/POPC/SP-B (7:3:1%) was less surface active than pure POPC plus 1% SP-B either in the presence or absence of calcium. Our findings suggested that the molecular composition and organization of mixed monolayers play an important role in the surface activity of the surfactant.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1992

Liver ultrasound findings in a low prevalence area of S. japonicum in China: comparison with history, physical examination, parasitological and serological results.

The paper describes a study carried out in a community in Dongdian township, Anhui Province, People's Republic of China. Medical history and the results of a physical examination, ultrasound investigation, parasitological and serological tests for Schistosoma japonicum infection were compared in 661 persons of 169 households. A lack of correlation between parasitological and serological indicators of infection and morbidity was observed in this area of low (6.4%) prevalence and intensity of infection. The prevalence of abnormal ultrasound findings in the liver in this population was high (56%), and was significantly higher than the prevalence of S. japonicum infection. The abnormal ultrasound findings correlated with a history of schistosomiasis, and the correlation increased significantly according to the number of times treated and the time since the last treatment, which suggested that past parenteral treatment has a role in the high rate of abnormal liver ultrasound findings. The significant correlation between the qualitative and quantitative serological results and abnormal ultrasound parenchymal patterns suggests that cross-reactivity between the etiology of the parenchymal disease and these tests is occurring. The presence of HBsAg correlated with the composite presence of ultrasound abnormalities of the liver parenchyma: increased echogenicity, periportal fibrosis and/or nodules and irregular fibrosis, whereas a normal ultrasound pattern was associated with the absence of HBV antigenemia.

Adolescent↗
PubMed1992

Achieving universal health insurance in Korea: a model for other developing countries?

As developing countries explore alternative methods to provide universal health insurance coverage, one potential model is South Korea. In twelve years (from 1977 to 1989), Korea was able to achieve universal health insurance coverage first by mandating employer based health insurance coverage for medium and large firms and then by establishing regional health insurance systems for small firms, farmers and the self-employed. A government medical aid insurance program was instituted for low income citizens. The specifics of the plan and some of the issues encountered in implementing the plan may be of interest to developing countries who want to achieve universal health insurance while maintaining a significant role for the private sector.

Developing Countries↗
PubMed1992

Structural analysis of the O-antigen side chain polysaccharides in the lipopolysaccharides of Klebsiella serotypes O2(2a), O2(2a,2b), and O2(2a,2c).

The lipopolysaccharide (LPS) of Klebsiella serotype O2 is antigenically heterogeneous; some strains express multiple antigenic factors. To study this heterogeneity, we determined the structure of the O-antigen polysaccharides in isolates belonging to serotypes O2(2a), O2(2a,2b), and O2(2a,2c), by using composition analysis, methylation analysis, and both 1H and 13C nuclear magnetic resonance spectroscopy. The repeating unit structure of the 2a polysaccharide was identified as the disaccharide [----3)-beta-D-Galf-(1----3)-alpha-D-Galp-(1----] and was identical to D-galactan I, one of two O polysaccharides present in the LPS of Klebsiella pneumoniae serotype O1 (C. Whitfield, J. C. Richards, M. B. Perry, B. R. Clarke, and L. L. MacLean, J. Bacteriol. 173:1420-1431, 1991). LPS from serotype O2(2a,2b) also contained D-galactan I as the only O polysaccharide, suggesting that the 2b antigen is not an O antigen. The LPS of serotype O2(2a,2c) contained a mixture of two structurally distinct O polysaccharides and provides a second example of this phenomenon in Klebsiella spp. One polymer was identical to D-galactan I, and the other polysaccharide, the 2c antigen, was a polymer with a disaccharide repeating unit structure, [----3)-beta-D-GlcpNAc-(1----5)-beta-D-Galf-(1----]. The 2c structure does not resemble previously reported O polysaccharides from Klebsiella spp. Periodate oxidation confirmed that D-galactan I and the 2c polysaccharide are distinct glycans, rather than representing domains within a single polysaccharide chain. Monoclonal antibodies against the 2c antigen indicated that only LPS molecules with the longest O-polysaccharide chains contained the 2c epitope.

Klebsiella↗
PubMed1992

Network analysis of Korean health insurance policy-making process.

This study examines how the decision-making process evolved in Korea during the initial phases of introduction and implementation of National Health Insurance. This study analyses the official documents and interviews views made with government officials and related personnel. We used the method of network analysis and multidimensional scaling in order to demonstrate how the major participants in the decision-making process developed and changed under the contemporary political situations. In the pre-implementation stage around 1976, major concerns were concentrated around the issues of financial support for social insurance, the fee schedule and who ought to be covered first. The total number of participants of the health or health-related organization was 61, which included the President, the Minister of Health and Social Affairs, representatives of special interest groups, etc. In the actual implementation period of 1982, different issues were brought up by the major participants. The number of participants in this period declined to 44 with the deletion of 19 and with the addition of two newly formed health insurance organizations. By 1988, as the implementation reached its final decision period, disagreements were centered on progressive premium rating and the administration of National Health Insurance. The number of participants increased to 60 after the addition of 16 participants. The analysis of this paper may provide some insight for other countries which wish to establish National Health Insurance; as reference to the policy-making process, it may provide some suggestions for when to initiate and how to formulate National Health Insurance policies.

Humans↗
PubMed1992

[Treatment of soil-transmitted helminth infections by anthelmintics in current use].

The efficacy of broad-spectrum anthelmintics in current use was studied in Hengshan County, Hunan Province. The vermicides under study include albendazole (400mg, single dose), mebendazole composite (mebendazole 100 mg and levamisole 25mg bid x 3d), oxantel pyrantel pamoate composite (pyrantel pamoate 150 mg and oxantel pamoate 150 mg bid x 2d), and pyrantel pamoate composite (base 10 mg/kg, single dose). Therapeutic effect assessed 2 weeks after medication revealed Ascaris egg negative rates or cure rates (CR) of 97.5-100% for the former 3 regimens, and 80.9% for the latter one; while CR for hookworm infection were 95.4%, 78.6-100%, 96.7% and 83.3%, respectively. A follow-up survey pursued 4 weeks post treatment showed no significant difference in CR for the above regimens. Judging from CR in Trichuris trichiura infection, pyrantel pamoate composite was recommended as the drug of choice (89.3%), which was followed by mebendazole composite (64.6-83.8%) and albendazole (28.2-42.6%), whereas pyrantel pamoate was inefficacious. Obvious egg reduction rates were evidenced post application of the above drugs in trichuriasis treatment except pyrantel pamoate at single dose.

Albendazole↗