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Biomedical subjects

S S Zhang

Publications and source records attributed to S S Zhang.

At least 19 recordsLinked to original sources
PubMed2005

Microsatellite mapping of a Triticum urartu Tum. derived powdery mildew resistance gene transferred to common wheat (Triticum aestivum L.).

A powdery mildew resistance gene from Triticum urartu Tum. accession UR206 was successfully transferred into hexaploid wheat (Triticum aestivum L.) through crossing and backcrossing. The F1 plants, which had 28 chromosomes and an average of 5.32 bivalents and 17.36 univalents in meiotic pollen mother cells (PMC), were obtained through embryos rescued owing to shriveling of endosperm in hybrid seed of cross Chinese Spring (CS) x UR206. Hybrid seeds were produced through backcrossing F1 with common wheat parents. The derivative lines had normal chromosome numbers and powdery mildew resistance similar to the donor UR206, indicating that the powdery mildew resistance gene originating from T. urartu accession UR206 was successfully transferred and expressed in a hexaploid wheat background. Genetic analysis indicated that a single dominant gene controlled the powdery mildew resistance at the seedling stage. To map and tag the powdery mildew resistance gene, 143 F2 individuals derived from a cross UR206 x UR203 were used to construct a linkage map. The resistant gene was mapped on the chromosome 7AL based on the mapped microsatellite makers. The map spanned 52.1 cM and the order of these microsatellite loci agreed well with the established microsatellite map of chromosome arm 7AL. The resistance gene was flanked by the microsatellite loci Xwmc273 and Xpsp3003, with the genetic distances of 2.2 cM and 3.8 cM, respectively. On the basis of the origin and chromosomal location of the gene, it was temporarily designated PmU.

Ascomycota↗
PubMed2001

Dysfunction of Stat4 leads to accelerated incidence of chemical-induced thymic lymphomas in mice.

Stat4 (signal transducer and activator of transcription) can be activated by specific cytokines, such as IL-12, IFN-alpha, and IL-2. Since IL-12 has been implicated in tumor surveillance and cancer treatment, we hypothesized that its signaling mediator, Stat4, may repress tumor growth. Mice lacking Stat4 allowed us to directly assess the role of Stat4 in tumor surveillance. Lymphomas were chemically induced by MNU (N-methyl-N-nitrosourea) injection in Stat4-deficient or wild-type control mice. At the time of termination of the experiment 16 weeks after injection, 78% of homozygous Stat4-deficient mice had developed thymic lymphomas. This tumor induction was dramatically higher than in heterozygous (14%) and wild-type controls (14%). Lymphoma development occurred 5 weeks earlier in homozygous knockout mice than in other genotypes. Mice bearing tumors were fragile and had an increased death rate in the early stages of the experiment. The tumors displayed a very aggressive phenotype with metastases in multiple organs. Therefore, the loss of Stat4 predisposes mice to tumor induction and demonstrates crucial roles of Stat4 in the prevention of tumors.

Animals↗
PubMed2001

The effect of zinc supplementation on antioxidant and lipid peroxidation status during Brachiaria decumbens intoxication in sheep.

An attempt was made to clarify the association between zinc (Zn) and antioxidants due to Zn supplementation on lipid peroxidation occurring during Brachiaria decumbens intoxication. The concentration of Zn, copper, malondialdehyde (MDA), superoxide dismutase (SOD), and gluthathione peroxidase (GSH-Px) were determined in tissues. There was a gradual increment in the concentration of Zn and MDA in serum and hepatocytic SOD in groups given Zn + B decumbens. A decline in erythrocytic GSH-Px and SOD, and lower concentration of reduced glutathione in hepatocyte cytosols were also detected in these sheep. It is highly suggestive that Zn supplementation may depress antioxidant status and enhance lipid peroxidation during B decumbens intoxication.

Animal Feed↗
PubMed2001

On-column amperometric detection of ofloxacin and pasiniazid in urine by capillary electrophoresis with an improved fractured joint and small detection cell.

An improved high-voltage electric field isolating joint and small detection cell have been carefully designed and fabricated. The joint possesses short steady time, high electric conductance efficiency and high performance. The cell is convenient to install and remove the capillaries with and without the joint, as well as to fix, adjust and insert the microelectrode into the detection capillary. Using the joint and the cell, an analytical method for determination of ofloxacin (Oflx) and pasiniazid (Ipa) in urine by capillary electrophoresis with on-column amperometric detection was developed. The calibration lines were linear in the range of 10-100 mg l-1 of Oflx and 1.0-50 mg l-1 of Ipa, respectively. The detection limits were 8.5 mg l-1 of Oflx and 0.80 mg l-1 of Ipa. Their recovery ranged from 101 to 104%. The accuracy and intra-day and inter-day reproducibility of Oflx and Ipa were determined with satisfactory results. This method was successfully used for determining Oflx and Ipa in human urine.

Aminosalicylic Acid↗
PubMed2001

[Analysis of chlorogenic acid in sunflower cake by thin-layer chromatography].

The analytical method of chlorogenic acid in sunflower cake by thin-layer chromatography(TLC) was developed. With 36% acetic acid as mobile phase and on the polyamide film plate, the Rf value of chlorogenic acid was 0.61. The calibration curve was linear in the range of 0.05 microgram-0.6 microgram of chlorogenic acid with the detection limit of 0.025 microgram and the average recovery of 97.53%. The inter-plate accuracy of chlorogenic acid was 2.57%. With 70% ethyl alcohol as extracting solvent and 30 min of extraction time, the amount of chlorogenic acid in the extract, the residue amount of chlorogenic acid in the sunflower cake and the extraction rate were determined and calculated by applying this method. The optimal time of extraction was found.

Calibration↗
PubMed2000

Sensitive detection of a plant virus by electrochemical enzyme-linked immunoassay.

The electrochemical enzyme-linked immunoassay increases the sensitivity of the detection of cucumber mosaic virus (CMV) by 5-fold compared with the spectrophotometric o-phenylenediamine (OPD) enzyme-linked immunosorbent assay (ELISA). The detection limit for the purified CMV is 1.0 ng/mL and the highest dilution ratio of the infected leaf sap is 1:5.0 x 10(4). The method is based on coupling the oxidation reaction of o-aminophenol (OAP)-H2O2 catalyzed by HRP-IgG conjugate with the electro-reduction of the enzymatic product. The enzymatic product 2-aminophenoxazine-3-one exhibits a sensitive second order derivative linear-sweep voltammetric response at the potential of -0.65 V (vs. Ag/AgCl) in pH 8.0 Britton-Robinson (B-R) buffer solution. So it can be applied to the detection of the plant virus with highly improved sensitivity.

Cucumovirus↗
PubMed2000

Effects of copper overload on hepatic lipid peroxidation and antioxidant defense in rats.

The influence of copper (Cu) overload on hepatic lipid peroxidation and antioxidation defense capacity was studied by overloading rats with copper sulphate orally (500 mg Cu/kg bw) 5 d/w for 8 w. Malondialdehyde (MDA), Cu-Zn superoxide dismutase (SOD), and Se-glutathione peroxidase (GSH-Px) were measured in serum and liver homogenate at 2, 4 and 8 w of dosing. Liver Cu concentration and alanine aminotransferase (ALT) activity were also determined. As Cu loading progressed, there were multiparameter changes with significant ALT elevation, increased MDA concentrations in serum and liver homogenate, and dramatic declines of SOD and GSH-Px activities in erythrocytes and whole blood respectively, along with marked elevation of hepatic Cu in the Cu-dosed group. Excessive Cu accumulation in the liver depressed SOD and GSH-Px activities and resulted in high MDA in serum and liver homogenate due to the lipid peroxidation induced by the Cu overload.

Administration, Oral↗
PubMed2000

The concentration of selected minerals and phytate in Malaysian Brachiaria decumbens.

Samples of Brachiaria decumbens collected from 5 farms representing the Peninsular Malaysia were subjected to selected trace mineral and phytate analyses to explain the pathogenesis of B decumbens intoxication. Concentrations of Cu, Zn, Fe and Mo were comparable to other grasses while that of phytate was low. The molar ratios of Cu:Zn, Cu:Mo, and Cu:Fe warrant that Cu deficiency is involved in the toxicity of B decumbens. This might aggravate the development of photosensitization of unpigmented or lightly pigmented areas of affected animals. The Zn:phytate ratio could predispose to Zn deficiency during intoxication.

Animals↗
PubMed2000

[Analysis of 1-(2,6-dichlorophenyl)-2-indolone and related materials by high performance liquid chromatography].

The separation of 1-(2,6-dichlorophenyl)-2-indolone (DCI) and related materials in the synthesis of medical intermediate DCI from 2, 6-dichlorophenol and phenylamine was investigated with high performance liquid chromatography under different chromatographic conditions. The results showed that DCI and related materials were in baseline separation by using CLC-CN(150 mm x 6.0 mm i.d., 7 microns) as column, MeOH-H2O(6:4, V/V) as mobile phase and a flow-rate at 1 mL/min. A rapid, accurate and reproducible HPLC method for determining DCI was developed. Fine and crude DCI samples were detected, results showed that N-(2,6-dichlorodiphenyl)-chloracetyl amide (CBCC) was the main impurity in fine sample, and CBCC and 2,6-dichlorodiphenylamine were the main impurities in the crude one.

Aniline Compounds↗
PubMed1999

Assessment of decisions in the treatment of Helicobacter pylori-related duodenal ulcer: a cost-effectiveness study.

AIMS: Many treatment trials for Helicobacter pylori have been reported but few have evaluated treatment in terms of both cost and effectiveness. It is important to find a therapy with a high eradication rate and low cost, especially in China. The aim of the study is to assess the efficiency of therapy for duodenal ulcers, including ulcer healing, H. pylori eradication and ulcer recurrence. METHODS: Ninety-six consecutive patients with duodenal ulcers and H. pylori infection were randomly allocated into two groups: AMT group (amoxycillin + metronidazole + tagamet); OA group (omeprazole + amoxycillin). Side-effects were recorded during the treatment period. Endoscopic examinations were repeated at the 7th or 8th week to assess ulcer healing. Patients were followed up for 6 months and repeat endoscopy was performed. Ulcer healing rate, H. pylori eradication rate and ulcer recurrence rate were compared. All costs were recorded and a cost-effectiveness analysis was conducted. RESULTS: In the AMT and OA groups, the ulcer healing rate was 83.7 and 93.5%, respectively (P = 0.27). The eradication rate of H. pylori was 65.1 and 69.6%, respectively and was significantly higher in patients with an ulcer diameter < or = 1 cm compared with those with an ulcer diameter > 1 cm, irrespective of treatment group. There was no difference in recurrence rate, duration of pain or the time lost because of the disease. Moderate or severe side-effects were found in 8.9% in AMT group and 6.5% in OA group. The cost of treatment for ulcer healing, H. pylori eradication and reduction in ulcer recurrence were all lower in the AMT group than in the OA group. Sensitivity analysis supported the result that AMT was more cost effective than OA. CONCLUSIONS: The AMT therapy was more effective and less costly than the OA therapy, especially in patients with H. pylori-related duodenal ulcers < 1 cm diameter.

Adolescent↗
PubMed1998

Comparison of high-performance capillary electrophoresis and liquid chromatography on analysis of zinc 5-aminosalicylate dihydrate and related materials.

Separation and determination of zinc 5-aminosalicylate dihydrate (ZASA) and related materials by high-performance capillary electrophoresis (HPCE) and liquid chromatography (HPLC) have been studied systematically. The R.S.D. of peak time and area and detection limits of materials were lower in HPLC compared to HPCE. HPCE and HPLC were used for determining ZASA and related materials in crude and treated ZASA using acid and heat, and similar results with both techniques showed the principal impurities in the crude ZASA were 5-aminosalicylic acid (ASA) and salicylic acid (SA), the compounds from ZASA decomposing under conditions of acid and heat were ASA, p-aminophenol and 5-benzeneazosalicylic acid.

Aminophenols↗
PubMed1998

Molecular epidemiology and variation of hepatitis B in recent immigrant families to Australia.

Natural variation in hepatitis B virus (HBV) was studied in asymptomatic carriers originating from countries of high endemicity. HBV DNA was detected by dot blot and/or polymerase chain reaction (PCR) in 34 of the 184 members of 22 new immigrant families who agreed to be tested after one of their children had been found to have current or past hepatitis B in a school survey. PCR products from both the S and distal-X pre-C regions were sequenced. One vaccinated child had the classical "escape" mutation at amino acid position 126 in the S-gene and two other children and two adults had other substitutions at amino acid positions 133, 120, 165, and 159. Mutations were more frequent in the distal-X pre-C region and included two pre-C mutants and 13 other amino acid substitutions. The strains originating in the various countries were placed in almost identical groups by phylogenetic analysis using each amplicon, and determination of subtype by antigenic analysis gave the same result as sequencing. The S-data allowed recognition of three dominant strains within genotype B, while the distal-X pre-C data provided better discrimination between family groups. No change was found when the sequence of samples obtained for the study was compared with those collected from 14 of the children two years earlier. There was some evidence of horizontal spread in addition to vertical transmission. Reports of mutations of HBV in patients with severe or unusual clinical features should be interpreted with caution until the prevalence of the mutant in asymptomatic carriers has been determined.

Adolescent↗
PubMed1998

A reproducible, simple, and sensitive high-performance capillary electrophoresis method for simultaneous determination of capreomycin, ofloxacin and pasiniazide in urine.

Separation and determination of capreomycin (Cp), ofloxacin (Oflx) and pasiniazide (Ipa) in urine by high-performance capillary electrophoresis (HPCE) with 280 nm detection have been studied systematically. The calibration lines were linear in the range of 0.5 approximately 50 mg 1(-1), and the detection limits (S/N = 3) were 0.15, 0.20 and 0.10 mg 1(-1) for Cp, Oflx and Ipa, respectively. The recoveries for these materials from urine were higher than 93.5%. The accuracy and intra- and inter- day reproducibility of Cp, Oflx and Ipa were determined with satisfactory results. This method was successfully used for determining Cp. Oflx and Ipa in human urine.

Aminosalicylic Acid↗
PubMed1997

Expression of multiple thyroid hormone receptor mRNAs in human oocytes, cumulus cells, and granulosa cells.

Thyroid hormones have diverse effects on ovarian function. We examined the expression of thyroid hormone receptor (TR) mRNAs (including TRalpha-1, TRbeta-1, TRbeta-2, and c-erbAalpha-2 isoforms) in three types of cells from human follicles, and determined the concentration of free tri-iodothyronine (T3) present in human follicular fluid. Human failed-fertilized oocytes, granulosa (GC) and cumulus (CC) cells from patients of the in-vitro fertilization (IVF) programme at Alliant Hospital Fertility Center were used to detect TR mRNA expression using reverse transcription-polymerase chain reaction (RT-PCR) followed by Southern blot analysis. Human spermatozoa were also analysed to determine whether results obtained with CC would be affected by the presence of spermatozoa. beta-Actin mRNA was amplified in each cell type as a positive control for the RT-PCR. Our results show that human oocytes express TRalpha-1, TRbeta-1, TRbeta-2, and c-erbAalpha-2 mRNAs and that these same isoforms are expressed in both human granulosa cells and cumulus cells. No differences were detected in the apparent amounts of RT-PCR products when comparing GC with CC, suggesting a similar pattern of expression of these RNAs. beta-actin mRNA was detected in spermatozoa, but TRalpha-1 expression was not detectable. The concentrations of free T3 measured in follicular fluid were similar to, or slightly below, those in serum of euthyroid patients. These data demonstrated that several isoforms of TR mRNA are expressed in the human oocyte, and hence thyroid hormone may have direct affects on the oocyte, as well as on GC and CC. In addition thyroid hormone may have indirect effects on the oocytes via the CC.

Female↗
PubMed1996

Properties of practical oral liposome-Streptococcus mutans glucosyltransferase vaccines for effective induction of caries protection.

Here we report the effectiveness of various liposome vaccines containing Streptococcus mutans glucosyltransferase (GTF) in protecting against dental caries after oral immunization. Rats were immunized by gastric intubation of the appropriate liposome vaccine at weaning and boosted 3 times. Rats were infected with S. mutans following initial immunization and fed cariogenic diet (Diet 305). Saliva and serum were collected during the study and assessed for antibody activity by enzyme-linked immunosorbent assay. Mandibles were removed on day 47 and assessed for S. mutans levels and then for caries. Animals immunized with sonicated, filtered and microemulsified GTF liposome preparations had decreased levels of dental caries compared with control animals given empty liposomes. Rats given dehydrated/rehydrated or purified liposomal GTF also had significantly less caries than control group (GTF alone). Because of economy, ease of preparation and efficiency in amount of antigen used, filtered, dehydrated/ rehydrated and purified liposomal GTF preparations are most practical for use in further assessing the efficacy of liposomal GTF in oral immunization.

Analysis of Variance↗
PubMed1996

[Antagonism of piracetam on the amnestic effect of diazepam in mice].

In step-down test, diazepam (1 mg.kg-1 po, 1 h before training) was shown to significantly impair memory acquisition in mice. But piracetam (200 mg.kg-1 ip, 1 h before training) was found to improve the diazepam-induced impairments of learning. By photocell cage method, piracetam showed no significant inhibitory effect on the diazepam-induced spontaneous motor activity in mice. In Y-maze test, Glutamic acid (0.1 microgram, icv, 3 min before training) significantly improved learning in normal mice and the amnesic effect of GABA and diazepam were completely antagonized by Glutamic acid and piracetam (200 mg.kg-1 ip, 1 h before training). These results suggest that increasing GABA-ergic neuronal transmission is unfavorable to learning and memory, but increasing Glu-ergic transmission is contrary to the former. It seemed that the presence of Glu/GABA system in the brain could regulate learning and memory.

Amnesia↗
PubMed1996

[Effects of L-malate, an inhibitor of glutamate decarboxylase, on learning and memory in mice].

Oral administration of L-malate 600 mg.kg-1 for 5 days before training can significantly promote memory acquisition, consolidation and retrieval, respectively, on anisodine-, chloramphenicol-, and ethanol-induced memory impairment in mice. Ketamine (8.5 mg.kg-1, i.p.), a selective NMDA receptor antagonist, was found to inhibit the anti-amnesic activity of L-malate. The glutamate (Glu) and GABA content in mice brain was measured by high-performance liquid chromatography with fluorescence detection. The content of GABA was shown to be decreased from 2.3 +/- 0.5 mumol.g-1 to 1.3 +/- 0.5 mumol.g-1 (P < 0.01), so the Glu/GABA ratio was increased significantly. These results suggest that the decrease of cerebral GABA level and the increase of Glu/GABA ratio is favorable to learning and memory.

Animals↗