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Biomedical subjects

Z H Wang

Publications and source records attributed to Z H Wang.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Diagnosis and treatment of Sturge-Weber syndrome associated with retinal detachment].

OBJECTIVE: To access the diagnosis and treatment of Sturge-Weber syndrome at late stage. METHODS: The male patient aged 65 visited the eye clinic with presenting symptom of visual loss of the left eye for 2 months. Ocular examination disclosed a facial hemangioma with the size of 2 cm x 3 cm on the nasal side of the left upper eyelid associated with engorged bulbar conjunctival and episcleral vessels in the upper nasal quadrant. Ophthalmoscopy revealed total detachment of the retina. Esotropia was measured as 10 degrees. Intraocular pressure was 24 mmHg. Electroretinogram (ERG) demonstrated an indistinguished pattern. Posterior trans-scleral and ciliary body cryocoagulation was applied followed by external release of the subretinal fluid. RESULTS: The retina became reattached with visual acuity of 0.3 and intraocular pressure was 15 mmHg of the left eye at 5 months postoperatively. Fluorescein angiographical findings were consistent with diffuse hemangioma of the choroid. Follow-up study for 6 years revealed that the retina remained attached with visual acuity of 0.8 and essentially normal electroretinogram. CONCLUSION: The small facial hemangioma was the clue for the diagnosis of Sturge-Weber syndrome and cryocoagulation was the procedure of choice for the treatment of retinal detachment with favorable visual outcome.

Aged↗
PubMed2001

[Determination of mercury in hair and traditional Chinese medicines by cold vapour atomic absorption spectrometry].

The effects of various experimental conditions on the determination of mercury by cold vapour atomic absorption spectrometry were investigated. Under the optimum conditions, the detection limit of mercury was 0.5 ng.mL-1, and the sensitivity was 1.1 ng.mL-1. The calibration curve was linear in the range of 0-40 ng.mL-1. The analytical procedure of mercury by pressure dissociation method was established by using HNO3, H2SO4 and H2O2(4 + 1 + 1) as oxidant, SnCl2 as reductant in acid medium. The analysis method was successfully applied to the determination of mercry in certified reference material of hair and traditional Chinese medicines, the relative standard deviations were 3.2%, 1.5% and 0.24% respectively. The recovery of mercury was 94.6%-102%. The results obtained were satisfactory. Air can been used as carrier gas instead of high purity argon.

Cold Temperature↗
PubMed2001

[Determination of arsenium and lead in traditional Chinese medicines by graphite furnace atomic absorption spectrometry].

The samples were processed by pressure dissociation method and by using HNO3-HClO4 as oxidant. The matrix modifiers were PdCl2 for As and (NH4)2HPO4 for Pb. The effects of matrix modifier quantity, ashing temperature, atomization temperature and element interference on the determination of arsenium and lead were investigated. Under the optimum conditions, arsenium and lead in traditional Chinese medicines were determined by graphite furnace atomic absorption spectrometry. The linear range of calibration curve was 0-300 ng.mL-1 and 0-80 ng.mL-1, the detection limit was 3.75 ng.mL-1 and 1.8 ng.mL-1, the sensitivity was 9.3 ng.mL-1 and 2.6 ng.mL-1, the mean recovery was 95.7% and 99.6%, respectively to As and Pb. The method is simple, rapid, sensitive, accuracy and of high practical application value.

Arsenic↗
PubMed2001

[Effects of millimeter wave combined with gamma-ray radiation on human tongue squamous cell carcinoma cell].

OBJECTIVE: To observe the effects of millimeter wave combined with (60)Co gamma-ray radiation on human tongue squamous cell carcinoma cell(Tca8113). METHODS: Using mm-wave combined with (60)Co gamma-ray to irradiate Tca8113 cell suspensions. The colony forming inhibition efficiency was observed three weeks later. 24 hours after radiation, the samples were observed under electron microscope. RESULTS: The study showed that the radiation could result in significant decrease of the colony forming efficiency (P<0.001). The inhibition efficiency was higher when the samples were exposed to high power density mm-wave or for a long duration (P<0.05 or P<0.01). The inhibiting effect in combined groups was more obvious than in singly radiated group (P<0.001 or P<0.05). There was no difference between 'R+HL' group and 'HL+R' group (P>0.05). Electron microscopy showed the cells' suprastructures had some injuries and regressive changes. And more serious changes existed in 'H' group. CONCLUSION: It could be concluded that mm-wave radiation could efficiently inhibit the colony forming capability of Tca8113 cell. And mm-wave radiation could lead to morphological changes of exterior or interior ultrastructures of Tca8113 cell.

English Abstract↗
PubMed2000

Origin of the native driving force for protein folding.

We derive an expression with four adjustable parameters that reproduces well the 20x20 Miyazawa-Jernigan potential matrix extracted from known protein structures. The numerical values of the parameters can be approximately computed from the surface tension of water, water-screened dipole interactions between residues and water and among residues, and average exposures of residues in folded proteins.

Electrochemistry↗
PubMed2000

Solid phase microextraction/gas chromatography of Salmonella-infected beef.

Eight strains of Salmonellae were incubated in TSB culture medium at 37 degrees C for 24 h. Volatile compounds derived from the bacteria were collected using solid-phase microextraction fibers and then applied to gas chromatography (GC). Similarity analysis of the GC patterns thus obtained could separate these strains on principal component similarity (PCS) scattergrams. Five major food-related pathogenic bacteria and 10 other bacteria (including one Salmonella strain) were also classified by growing in the same medium. It is then proposed to utilize this approach to improve the GC/PCS method of Nakai et al. [Nakai, S.; Wang, Z. H.; Dou, J.; Nakamura, S.; Ogawa, M.; Nakai, E.; Vangerstoep, J. J. Agric. Food Chem. 1999, 47, 576-583] that has been developed for screening safe foods by detecting bacteria contaminated foods. Inoculating food samples pre-enriched through preliminary incubation into a culture medium and then subjecting to the GC/PCS method after secondary incubation enhances the detectability of pathogenic bacteria.

Animals↗
PubMed2000

Isolation and characterization of the normal canine beta-galactosidase gene and its mutation in a dog model of GM1-gangliosidosis.

The acid beta-galactosidase cDNA of Portuguese Water dogs was isolated and sequenced. The entire coding region of the gene consists of 2004 nucleotides encoding a protein of 668 amino acids. Its encoding sequence indicates approximately 86.5% identity at the nucleotide level and about 81% identity at the amino acid level with the encoding region of the human acid beta-galactosidase gene. The deduced amino acid sequence contains a 24-amino-acid putative signal sequence, six possible glycosylation sites, and seven cysteine residues. A homozygous recessive mutation, causing canine GM1-gangliosidosis, was identified at nucleotide G200-->A in exon 2 resulting in an Arg60-->His (mutation R60H) amino acid substitution. The mutation creates a new restriction enzyme site for Pml1. Genotyping 115 dog samples for this acid beta-galactosidase gene alteration readily distinguished affected homozygous recessives (n=5), heterozygous carriers (n=50) and normal homozygotes (n=60). DNA mutation analysis provided a method more specific than enzyme assay of beta-galactosidase for determination of carriers.

Amino Acid Sequence↗
PubMed2000

Toxin in bullous impetigo and staphylococcal scalded-skin syndrome targets desmoglein 1.

Exfoliative toxin A, produced by Staphylococcus aureus, causes blisters in bullous impetigo and its more generalized form, staphylococcal scalded-skin syndrome. The toxin shows exquisite specificity in causing loss of cell adhesion only in the superficial epidermis. Although exfoliative toxin A has the structure of a serine protease, a target protein has not been identified. Desmoglein (Dsg) 1, a desmosomal cadherin that mediates cell-cell adhesion, may be the target of exfoliative toxin A, because it is the target of autoantibodies in pemphigus foliaceus, in which blisters form with identical tissue specificity and histology. We show here that exfoliative toxin A cleaved mouse and human Dsg1, but not closely related cadherins such as Dsg3. We demonstrate this specific cleavage in cell culture, in neonatal mouse skin and with recombinant Dsg1, and conclude that Dsg1 is the specific receptor for exfoliative toxin A cleavage. This unique proteolytic attack on the desmosome causes a blister just below the stratum corneum, which forms the epidermal barrier, presumably allowing the bacteria in bullous impetigo to proliferate and spread beneath this barrier.

Animals↗
PubMed2000

Type specificity and significance of different isotypes of serum antibodies to human papillomavirus capsids.

Isotype-specific serum antibody responses against human papillomavirus (HPV) type 16 were evaluated by use of cross-sectional, prospective, and population-based seroepidemiologic studies. IgG1 and IgA were the most abundant isotypes. No sample contained IgG2, and <25 samples contained IgG3 or IgM. Total IgG, IgA, and IgG1 were HPV type specific and were associated with HPV-16 DNA (odds ratios [ORs], 5.4, 5.0, and 5.9, respectively; P<.001) but not with other HPV DNA (ORs, 1.2, 1.2, and 0.8, respectively; P value was not significant). Total IgG and IgG1 were strongly associated with number of lifetime sex partners (P<.001); IgA was only associated with number of recent sex partners and lifetime sex partners among younger women. Total IgG, IgG1, and IgA were associated with cervical intraepithelial neoplasia type III and also predicted risk of future cervical neoplasia. IgG and IgG1 appeared to mark lifetime cumulative exposure, whereas IgA may mark recent or ongoing infection.

Adolescent↗
PubMed2000

Trafficking of varicella-zoster virus glycoprotein gI: T(338)-dependent retention in the trans-Golgi network, secretion, and mannose 6-phosphate-inhibitable uptake of the ectodomain.

The trans-Golgi network (TGN) is putatively the site where varicella-zoster virus is enveloped. gE is targeted to the TGN by selective retrieval from the plasmalemma in response to signaling sequences in its endodomain. gI lacks these sequences but forms a complex with gE. We now find that gI is targeted to the TGN and plasma membrane when expressed in Cos-7 cells; nevertheless, surface labeling revealed that gI is not retrieved from the plasma membrane. TGN targeting of gI depended on the T(338) of its endodomain and was lost when T(338) was deleted or mutated to A, S, or D. The endodomain of gI was sufficient, if it contained T(338), to target a fusion protein containing the ectodomain of the human interleukin-2 receptor to the TGN. A truncated protein consisting only of the gI ectodomain was secreted and taken up by nontransfected cells. This uptake of the secreted gI ectodomain was blocked by mannose 6-phosphate. Following cotransfection, both gI and gE were retrieved to the TGN from the plasma membrane in 26.7% of cells, neither gI nor gE was internalized in 18.3%, and gE was retrieved to the TGN while gI remained at the plasma membrane in 55%. We suggest that the T(338) of its endodomain is necessary to retain gI in the TGN; moreover, because gI and gE interact, the signaling sequences of each glycoprotein reinforce one another in ensuring that both glycoproteins are concentrated in the TGN yet remain on the cell surface.

Amino Acid Sequence↗
PubMed2000

[Imaging ellipsometry in biomolecule research].

Imaging Ellipsometry is an optical surface-sensitive method for the investigation of various aspects of biomolecules adsorbing mainly at reflecting metal surfaces and silicon surface. It has advantages of high sensitivity to layer-thickness, big area of view, high sampling speed, and high lateral resolution. It can be used for studying adsorption kinetics of biomolecules and detecting complex layer of antigen-antibody when antibody (or antigen) combined with antigen (or antibody) coated on solid surfaces. Compared with other solid phase methods such as enzyme linked immunosorbent assay, immunofluorescence and radioimmunoassay, imaging ellipsometry has the advantage of not involving any labelling of reactants and it is a relatively inexpensive method and easy to handle. Compared with traditional ellipsometer, imaging ellipsometry shows an advantage of distinguishing both affinity and non-specific binding in different area on the surfaces.

Adsorption↗
PubMed2000

[Expression of 3'-truncated preS/S gene in transgenic mice].

The 3'-truncated preS/S region from HBV genome, encoding a transcriptional transactivator, was cloned and a recombination expression vector for 3'-truncated HBV preS/S sequences under the control of the CMV promoter was constructed by recombination DNA techniques. Then, the expression vector DNA was microinjected into pronuclei of fertilized mouse oocytes. Founders of transgenic mice harbouring the recombination gene which can be expressed were screened by polymerase chain reaction (PCR) at genomic DNA level and confirmed by ELISA andlysis at protein level. Two of 15 mice in one series of microinjections showed the expression of 3'-truncated preS/S gene from HBV genome. The expression vector of 3'-truncated preS/S gene might be helpful for further studies of relationship between the expression production of 3'-truncated preS/S sequence and HBV-associated oncogenesis in vitro. The transgenic mice with expressing 3'-truncated preS/S gene will provide new insight into its roles in the development of human hepatocelluar carcinoma (HCC) in vivo.

Animals↗
PubMed2000

The suppression effect of light rare earth elements on proliferation of two cancer cell lines.

To study the suppression effect of light rare earth elements (RE) on proliferation of two cancer cell lines. Two cancer cell lines PAMC82 and K562 were used to examine their colony-forming ability in soft agar, microtubule structure, calmodulin levels and regulation of some gene expressions by Northern blot analysis with and without treatment by RE. The results showed that on soft agar culture the colony-forming ability of human gastric cancer cell line PAMC82 treated by RE chloride decreased and the PAMC82 cell microtubule abnormal structure became normal. The calmodulin (CaM) levels decreased in human leukemia cells (K562) treated with cerium chloride and neodymium chloride. The Northern blot analysis revealed marked up-regulation of p53, p16(MTS1), p21 (WAF1) gene expressions in PAMC82 cells treated with lanthanum chloride and cerium chloride, as compared to control PAMC82 cells. The light rare earth elements studied have certain suppression effects on proliferation of cancer cells. This effect might be related to the decrease of calmodulin and up-regulation of some gene expressions in cancer cells.

Calmodulin↗
PubMed2000

[A rapid, isocratic method for analysis of phospholipids by reversed-phase high performance liquid chromatography].

Linear calibration curves were obtained for 4.5-10.5 micrograms of phosphatidylcholine(PC), 1.5-3.5 micrograms of phosphatidic acid(PA), 9.0-21.0 micrograms of cardiolipin(CL), 2.25-5.25 micrograms of phosphatidylglycerol(PG) by reversed-phase high performance liquid chromatography with UV detector at 205 nm, P-E C18 column (15 cm x 0.46 cm i.d., 5 microns) and isocratic elution with mobile phase of methanol-acetonitrile-water (79:8:13, V/V/V) at a flow rate of 2.0 mL/min. Separation and detection of these four standards were achieved reproducibly and easily in less than 12 minutes. The RSDs of peak area measurements were from 0.77% to 8.86%. Average recovery of PC was 89.21% (RSD = 2.1%). The air-dried bear biles were ground into powder and extracted continuously with chloroform-methanol (1:1, V/V) to a final dilution 25 folds the volume of the sample. The extract was washed by addition of half its volume of 0.58% aqueous NaCl. The resulting mixture separated into two phases. The lower phase was the total pure lipid extract and was dried at room temperature under nitrogen. The lipid residue was dissolved in methanol to the desired volume and injected into the HPLC system for analysis. The results indicated that six kinds of bear biles had differences in the phospholipid composition. The method enables a simple, rapid and reproducible quantification of PC, PA, PG and CL.

Animals↗
PubMed1999

Intra-A chain disulphide bond forms first during insulin precursor folding.

In this study, we investigated the folding pathway of insulin precursor and compared it with that of insulin-like growth factor I (IGF-I). The intra-A chain disulphide bond was found to form early in insulin precursor folding, whereas the corresponding disulphide bond in IGF-I formed late. Intra-A chain disulphide-bond deleted [A6, A11-Ser] proteins, including proinsulin, insulin, and A chain, were employed for this investigation. Under the same conditions the recombination yield of insulin from S-sulphonates of native A and B chains was 22%, while the yield of [A6, A11-Ser] insulin from S-sulphonates of [A6, A11-Ser] A chain and native B chains was only approx. 7%. This indicated that the intra-A chain disulphide bond may serve to stabilize the A chain folding intermediate so as to facilitate the correct recognition and pairing with the B chain. Time courses of oxidation of reduced insulin A chains, reduced A and B chains, and reduced proinsulins showed that the intra-A chain disulphide bond formed first during insulin precursor folding. The formation of intra-A chain disulphide bond further accelerated the formation of the other two inter-chain disulphide bonds. The time course of helix structure formation of insulin A chains also indicated that the intra-A chain disulphide bond formed first, and could stabilize partially folded A chain helix structure. The rate of intra-A chain disulphide bond formation was almost the same as that for both helix structure formation and insulin molecule formation, indicating that the formation of the intra-A chain disulphide bond was the rate limiting step for the folding of insulin precursor.

Circular Dichroism↗
PubMed1999

Effects of CO2 and H+ on laryngeal receptor activity in the perfused larynx in anaesthetized cats.

1. Intralaryngeal CO2 reflexly decreases ventilation and increases upper airway muscle activity. Topical anaesthesia of the laryngeal mucosa or cutting the superior laryngeal nerves (SLNs) abolishes these reflexes, indicating that the receptors responsible are superficially located and that their afferent fibres are in the SLN. Intralaryngeal CO2 affects the activity of receptors recorded from the SLN. 2. An isolated, luminally perfused laryngeal preparation was developed in anaesthetized, paralysed cats in order to compare the effects of solutions with varying levels of pH and PCO2 on pressure-sensitive laryngeal receptor activity. Since the pH of tracheal surface fluid is reported to be approximately 7.0, two neutral (pH 7.4 and 7.0) and two acidic (pH 6.8 and 6.3) solutions were used. 3. Compared with neutral acapnic control solutions, neutral hypercapnic (PCO2 64 mmHg) solutions either excited or inhibited the discharge of 113 out of 211 pressure-sensitive SLN afferents. In 24 receptors, the effects of hypercapnic solutions with either neutral or acidic pH were similar in both direction and magnitude. In 50 receptors affected by neutral hypercapnic solutions, acidic acapnic solutions had no effect on 66 % of units and significantly smaller effects in the remaining units. In 17 receptors, the effects of neutral solutions with a PCO2 of 35 mmHg were significantly less than for neutral solution with a PCO2 of 64 mmHg. 4. These results show that the effects of CO2 on laryngeal pressure-sensitive receptors are independent of the pH of the perfusing media, and suggest that acidification of the receptor cell or its microenvironment is the main mechanism of CO2 chemoreception.

Air Pressure↗
PubMed1999

Tradescantia bioassays for the determination of genotoxicity of water in the Panlong River, Kunming, People's Republic of China.

The Panlong river passes through Kunming City and receives a large quantity of municipal sewage and wastewater from industrial effluent. Along the river, 20 sites were selected to collect water samples to assess the genotoxicity using two Tradescantia assays, the micronucleus (Trad-MCN) and the stamen-hair-mutation (Trad-SHM) assays. The lowest frequencies in the Trad-MCN assay and the Trad-SHM assay are 3.19 MCN/100 tetrads and 1.32 M/1000 stamen hairs, respectively. In the water samples obtained from the Songhua Reservoir, the MCN frequencies and mutation rates are not statistically significantly different from the data found for the negative control (2.49 MCN/100 tetrads and 0.71 M/1000 stamen hairs). Among the other water samples, 19 in Trad-MCN assay and 17 in Trad-SHM assay show significantly higher genotoxicity than the control. The highest genotoxicity was in samples No. 19 for the MCN assay (8.73 MCN/100 cells), over three times higher than the negative control, and in sample No. 11 for the SHM assay (4.30 M/1000), six times higher than the negative control, and were about the same as for the positive control (10.0 mg/l NaN3, 9.28 MCN/100 tetrads and 7.44 SHM/1000 stamen hairs), respectively. The peak frequencies for the Trad-MCN assays were observed in the water samples obtained from the sites that were near industrial and municipal wastewater that ran into the river as effluent. In general, the frequency of MCN and SHM mutations increased where the river passed through Kunming. The Trad-MCN assay seemed more sensitive than that of the Trad-SHM assay in detecting genotoxicity of the river water pollution.

Biological Assay↗