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Biomedical subjects

W Yang

Publications and source records attributed to W Yang.

At least 505 records · Page 28Linked to original sources
PubMed1994

Capsid assembly and involved function analysis of twelve core protein mutants of duck hepatitis B virus.

The roles of different regions of the duck hepatitis B virus (DHBV) core protein on viral capsid assembly and related functions were examined. Twelve deletion and insertion mutations which covered 80% of the DHBV C open reading frame were constructed and expressed in Escherichia coli. The N-terminal region (amino acids 3 to 66) of DHBV core protein was important for its tertiary structure and function in E. coli. The expressed core mutants without this region apparently inhibited E. coli growth. The results of transmission electron microscopy of E. coli thin sections, capsid agarose gel, and sucrose gradient sedimentation demonstrated that a few DHBV core mutants with insertion in the N terminus and deletion in the C terminus retained the ability to form core-like particles in E. coli. However, other mutations in most of N-terminal and central regions strongly inhibited the self-assembly ability of DHBV core protein in E. coli. In addition, the mutant with a C-terminal region deletion (amino acids 181 to 228) lost most of the nucleic acid-binding activity of the DHBV core protein.

Amino Acid Sequence↗
PubMed1994

[Clinical analysis of 24 cases of chordomas in the skull base].

Chordoma is a rare neoplasm which arises from the embryonic remnant of the notochord. The paper reported 24 cases of chordomas in the skull base. According to symptoms, signs, imaging features, operation findings, the original places and the expansive directions of the tumor, they were divided into four clinical types: sellar, clival, occipito-temporal and extent. The choices of surgical approaches were suggested on these types. They are difficult to remove because of their deep site, limit operative field and close to the important vessels, nerves and brain, and they recur frequently after operation.

Adolescent↗
PubMed1994

Corneal topographic analysis in patients with cataract.

We studied the corneal curvature of 161 eyes in 101 patients, aged from 50 to 80 years (mean: 63 years), with senile cataract using the Topographic Modeling System (TMS) preoperatively. The results revealed that mean surface asymmetry index (SAI) was 0.36 and mean surface regularity index (SRI) 0.79. Simulated keratometry reading (Sim K) was 44.46 D, and 43.56 D. Minimum K reading was 42.60 D. The same patterns of corneal topography in both eyes were 50% in 60 patients who had binocular examination. Astigmatism less than 1 D was 23% in 161 corneas. Corneal patterns included round (21.2%), oval 16.1%), symmetric and asymmetric bow-tie (22.2%), and irregular (40.4%). SRI and SAI of the irregular pattern were statistically higher than those of the round, oval and bow-tie patterns in our patients (P < 0.01 and P < 0.05). The results of our study determined that the cornea of eye with senile cataract preoperatively is not a perfect spherocylinder. It is asymmetrically aspheric, with less curvature peripherally than centrally.

Aged↗
PubMed1994

[Bacteriological detection of anterior chamber aspirate after extracapsular cataract extraction with intraocular lens implantation].

We cultured the anterior chamber aspirates of 83 patients with extracapsular cataract extraction and IOL implantation. Of the 83 cases, 5 (6.1%) had positive aspirates including 3 cases of staphylococcus epidermidis and 2 cases of staphylococcus aureus. No eye in our study developed bacterial endophthalmitis. Our study suggests that the anterior chamber of human eyes is capable of clearing a low inoculum of bacteria after cataract surgery without the development of bacterial endophthalmitis.

Aged↗
PubMed1994

Effects of inhibitor of endothelium-derived relaxing factor on hypoxic contraction of isolated pig coronary artery.

Exposure of isolated pig coronary artery with endothelium intact to hypoxia Krebs-Henseleit solution aerated with 95% N2 + 5% CO2 caused a transient contractile response, and the coronary artery without endothelium exhibited a gradual decrease in basal tension. The endothelium-dependent contractile response to hypoxia was almost completely blocked by nitro-L-arginine (0.2 mmol.L-1), and inhibited by methylthioninium chloride (10 mumol.L-1). The inhibitory effect of the NLA was partially reversed by L-arginine (2 mmol.L-1). Sodium nitroprusside (10 mumol.L-1) was also completely antagonized and nicorandil (0.3 mol.L-1) remarkably reduced the hypoxic contractile response. Tetraethylammonium (10 mmol.L-1) and glibenclamide (1 mumol.L-1) had little effect on hypoxia-induced vascular contraction, whereas cromakalim (1 mumol.L-1) produced obvious relaxing effect on hypoxic response. These results suggest that suppression of basally released nitric oxide (NO) is an important mechanism of coronary vasoconstriction induced by hypoxia.

Animals↗
PubMed1994

[The diagnosis and treatment of sphenoid inflammatory neoplasms and sphenoid sinus tumors].

We have analyzed the clinical data of 27 cases of sphenoid inflammatory neoplasms and sphenoid sinus tumors including inflammations (12 cases), benign tumors (10 cases) and malignant tumors (5 cases). The characteristics of sphenoid inflammatory neoplasms were compared with those of sphenoid sinus tumors. On CT scanning and magnetic resonance imaging (MRI) we found that sinusitis resulted in much less bony erosion than tumors on CT scanning and that the T2-signal intensity on MRI increased much more in sinusitis than in tumors. We have discussed the indications of various operative approaches and suggested that the approach of external ethmoidectomy is a method of choice.

Adolescent↗
PubMed1994

[Comparison of corneal topography and keratometer in patients with cataract preoperatively and postoperatively].

The comparison of corneal topography with keratometer in 200 patients (278 eyes) was made. The results revealed that Sim K values of corneal topography were 44.22D and 44.26D, mean diopters of keratometer were 44.16D and 44.23D in 150 eyes of 116 patients with cataract preoperatively. There was no significant difference between Sim K values of topography and diopters of keratometer (P > 0.05). The Sim K values of the topography were 46.37D and 43.06D and diopters of keratometer were 46.09D and 42.88D in 90 eyes of 67 patients who received cataract extraction with IOL implantation or second IOL implantation. No significance was found in results between Sim K values and diopters of keratometer in patients postoperatively (P > 0.05). Our investigation demonstrated that Sim K values of corneal topography were in agreements with diopters of keratometer in patients with cataracts preoperatively or postoperatively. However, corneal topography has great values in diagnosis of corneal diseases, traumatic astigmatism, severe non-rule stigmatisms, in which keratometer is often useless.

Adolescent↗
PubMed1994

[An investigation on the distribution of leptospirae interrogans in water and soil in southwest of Yunnan Province].

The conservation of pathogenic leptospirae in water and soil is one of the important problems of geography-epidemiological survey of leptospirosis. We have conducted this investigation by using of filtration-culture isolation method in five counties in the west and southwest of Yunnan during 1988-1992. The results showed that the isolates from samples of water and soil collected between July and September in Menglian and Huaping county were leptospirae biflexa while in the samples of water and soil collected between November and December in three counties, 8 strains of L. interrogans were isolated from the samples of Gengma and Baoshan county. The total positive rate was 3.31% (8/242). The positive rate of water and soil was 2.14% (3/140) and 4.9% (5/102) respectively. Strains obtained in this investigation belong to six serogroups: Icterohaemorrhagiae and Pyrogenes in 2 respectively. Canicola, Grippotyphosa, Sejroe and Australis in 1 respectively. These serogroups of leptospirae obtained from water and soil were corresponded with the serogroups obtained from the patients and animals with leptospirosis in local area. This survey provided new data for expounding the structure of the focus of leptospirosis.

China↗
PubMed1994

[Study on influence degree of probability of endemic factors for schistosomiasis transmission in Yunnan mountainous regions].

In Zhonghe Village of Weishan County, Yunnan Province, a schistosomiasis endemic area of mountainous valley subtype, an epidemiological investigation was conducted on its natural, biological and social factors influencing schistosomiasis transmission in 1987-1990. The results were analyzed by stratified sampling analysis and probability accumulation method. It was demonstrated that 12 of 29 factors were the most important factors influencing schistosomiasis transmission including annual average air-temperature, number of infection sources, number of spots with infected snails, water temperature and annual average rainfall, etc. The values of influence degree before and after intervention measures were 3.513 and 2.066, respectively, the decrease being 41%.

Animals↗
PubMed1994

[Parasitic circulating antigens in hosts with Filaria bancrofti].

The ELISA and Dot-ELISA with rabbit anti-Setaria labial-papillosa antibody were applied to determine circulating antigens of Filaria bancrofti. The total positive rate was 96% (24/25) in the sera of patients with microfilaremia from endemic areas, Anhui province. The total positive rate of urines was 60% (15/25) in the same patients. The positive rates of the milks were both 100% (4/4) in the same patients. The conformity rate was 100% and 75% respectively for positive sera and urines (15 cases), milks (4). Negative reactions were observed in the sera, urines and milks of all the 43 healthy people from non-endemic areas in Jiangsu province. Negative reactions were observed in the urines of all the 11 non-filaria cases harbouring intestinal nematodes. The positive rate detected with ELISA was 36% (4/11) in the patient sera that were negative when they were detected by Dot-ELISA. Negative reactions were detected with Dot-ELISA in the sera of all the 10 non-filaria patients infected with Paragonimus westermani. The results showed that circulating antigens of Filaria bancrofti exist not only in the serum but also in the urine and the milk.

Animals↗
PubMed1993

Cloning and functional expression of a Schistosoma japonicum cDNA homologous to the enolase gene family.

A cDNA encoding the complete open reading frame of Schistosoma japonicum enolase has been cloned. The 1494bp cDNA (C30) was isolated from a S. japonicum cDNA expression library immunoscreened with hyperimmune rabbit sera raised against soluble adult S. japonicum proteins. The ORF encodes a protein of 434 amino acids exhibiting 72% identity to human, murine, and rat enolases, and 62% identity to Saccharomyces cerevisiae enolase. The inferred molecular mass of the protein is 47,251 Daltons, similar to that reported for the enolases of other species. In vitro translation of C30 also generated a protein of 47kDa. After subcloning and expression, the recombinant protein was purified by affinity chromatography under non-denaturing conditions and shown to exhibit functional enolase enzymatic activity.

Amino Acid Sequence↗
PubMed1993

A stationary-phase protein of Escherichia coli that affects the mode of association between the trp repressor protein and operator-bearing DNA.

Highly purified preparations of trp repressor (TrpR) protein derived from Escherichia coli strains that were engineered to overexpress this material were found to contain another protein, of 21 kDa. The second protein, designated WrbA [for tryptophan (W) repressor-binding protein] remained associated with its namesake through several sequential protein fractionation steps. The N-terminal amino acid sequence of the WrbA protein guided the design of two degenerate oligonucleotides that were used as probes in the cloning of the wrbA gene (198 codons). The WrbA protein, in purified form, was found by several criteria to enhance the formation and/or stability of noncovalent complexes between TrpR holorepressor and its primary operator targets. The formation of an operator-holorepressor-WrbA ternary complex was demonstrated by gel mobility-shift analysis. The WrbA protein alone does not interact with the trp operator. During the stationary phase, cells deficient in the WrbA protein were less efficient than wild type in their ability to repress the trp promoter. It is proposed that the WrbA protein functions as an accessory element in blocking TrpR-specific transcriptional processes that might be physiologically disadvantageous in the stationary phase of the bacterial life cycle.

Amino Acid Sequence↗
PubMed1993

Myoglobin protects against endothelial cell membrane damage associated with hydrogen peroxide or xanthine/xanthine oxidase.

Oxymyoglobin at 'physiological' concentrations of 20-100 micromolar protected cultured endothelial cells from damage by xanthine/xanthine oxidase or by hydrogen peroxide. Metmyoglobin also provided a degree of protection, but apomyoglobin was ineffective. Protection was enhanced in the presence of ascorbate (0.01-1 mM). Myoglobin may have a physiological role in the protection of muscular tissue from ischaemia/reperfusion-induced damage.

Adenine↗