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G Wang

Publications and source records attributed to G Wang.

At least 343 records · Page 19Linked to original sources
PubMed1999

[Research on the mechanism of the fatty acid composition on the tumorigenic danger induced by chemical tumorigenic material].

Rats were given 5 kinds of diets which contained 15% (w/w) fat and different fatty acids composition. The rats were given methyl-nitrosurea (MNU) to induce colonic tumor. Proliferation cell nuclear antigen (PCNA), cell kinetics, membrane fluidity, the activity of alkaline phosphatase (ALP) and the content of prostaglandin E2(PGE2) in colonic mucosa were determined in order to assess the fatty acids composition on the colonic cell tumorigenesis. The results indicated that the cells of PCNA, cells of PI labeled in S period and the activity of ALP were the highest in the 3rd group which contained lowest saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) and highest n-6 polyunsaturated fatty acids. Whereas, these indexes and PGE2 were lowest and membrane fluidity was the best in the 4th group which contained the highest 1-3 PUFA. It is considered that the inhibition tumorigenesis of n-3 PUFA may be related to its effects of decreaing PCNA, PGE2, cells in S period and increasing membrane fluidity.

Animals↗
PubMed1999

[Apolipoprotein E polymorphism and its association with serum lipid level in Uygur nationalities from Xinjiang].

To study the relative frequency of apoE allele and the influence of polymorphism on serum lipid and lipoprotein concentration in Uygur nationalities, apoE phenotype was analysed by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) in 163 Uygurs and 150 Hans. Serum lipid levels were measured in 101 Uygurs and 140 Hans of them. The results showed that the frequency of E4 allele was higher in the Uygurs than in the Hans. Total cholesterol and low-density lipoprotein cholesterol were higher in the two nationalities who bear E 4 allele. It is concluded that the distribution of apoE genotypes and allele-frequencies was significantly different, but the trent for the relationship between apoE phenotype and lipid and lipoproteins was similar in the two nationalities.

Adult↗
PubMed1999

Chromosomal mutations induced by triplex-forming oligonucleotides in mammalian cells.

Specific recognition of a region of duplex DNA by triplex-forming oligonucleotides (TFOs) provides an attractive strategy for genetic manipulation. Based on this, we have investigated the ability of the triplex-directed approach to induce mutations at a chromosomal locus in living cells. A mouse fibroblast cell line was constructed containing multiple chromosomal copies of the lambdasupFG1 vector carrying the supFG1 mutation-reporter gene. Cells were treated with specific (psoAG30) or control (psoSCR30) psoralen-conjugated TFOs in the presence and absence of UVA irradiation. The results demonstrated a 6- to 10-fold induction of supFG1 mutations in the psoAG30-treated cells as compared with psoSCR30-treated or untreated control cells. Interestingly, UVA irradiation had no effect onthe mutation frequencies induced by the psoralen-conjugated TFOs, suggesting a triplex-mediated but photoproduct-independent process of mutagenesis. Sequencing data were consistent with this finding since the expected T.A-->A.T transversions at the predicted psoralen crosslinking site were not detected. However, insertions and deletions were detected within the triplex binding site, indicating a TFO-specific induction of mutagenesis. This result demonstrates the ability of triplex-forming oligonucleotides to influence mutation frequencies at a specific site in a mammalian chromosome.

Animals↗
PubMed1999

Tyramide signal amplification method in multiple-label immunofluorescence confocal microscopy.

The tyramide signal amplification (TSA) method has recently been introduced to improve the detection sensitivity of immunohistochemistry. We present three examples of applying this method to immunofluorescence confocal laser microscopy: (1) single labeling for CD54 in frozen mouse brain tissue; (2) double labeling with two unconjugated primary antibodies raised in the same host species (human immunodeficiency virus type 1 p24 and CD68) in paraffin-biopsied human lymphoid tissue; and (3) triple labeling for brain-derived neurotrophic factor, glial fibrillary acidic protein, and HLA-DR in paraffin-autopsied human brain tissue. The TSA method, when properly optimized to individual tissues and primary antibodies, is an important tool for immunofluorescence microscopy. Furthermore, the TSA method and enzyme pretreatment can be complementary to achieve a high detection sensitivity, particularly in formalin-fixed paraffin-embedded archival tissues. Using multiple-label immunofluorescence confocal microscopy to characterize the cellular localization of antigens, the TSA method can be critical for double labeling with unconjugated primary antibodies raised in the same host species.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Effects of haloperidol and clozapine on tongue dynamics during licking in CD-1, BALB/c and C57BL/6 mice.

RATIONALE: In an initial effort to describe how genetic background influences the differential motor effects of haloperidol, a drug with high extrapyramidal side effect (EPS) liability, and clozapine, an antipsychotic low in EPS, both drugs were studied in inbred strains of mice (BALB/c and C57BL/6) previously shown to have differential sensitivities to haloperidol. OBJECTIVES: Behavioral differences in lick dynamics for male BALB/c, C57BL/6 and CD-1 (an outbred strain) were characterized. Effects of dose ranges of haloperidol and clozapine were then evaluated in the three strains. METHODS: The mice learned to lick milk from a force-sensing disk during daily 2-min sessions, while a computer counted the number of licks and measured lick peak force and lick rhythm. After training, acute doses of haloperidol (0.08-2.0 mg/kg) or clozapine (0.5-8.0 mg/kg) were administered i.p. 45 min before sessions. RESULTS: Prior to drug treatment, substantial quantitative strain differences in licking behavior were observed: C57BL/6 mice made fewer licks, licked with lower peak force per lick, and had a slower lick rhythm than the BALB/c and CD-1 mice. As in rats, clozapine slowed the lick rhythm in all three mouse strains much more than haloperidol did. Haloperidol produced a 50% greater suppression of number of licks in BALB/c than in C57BL/6 mice (ED50 values were 0.82 mg/kg and 1.22 mg/kg, respectively). For clozapine, lick suppression was greater in the C57BL/6 than in the BALB/c strain (ED50 values were 1.88 mg/kg and 2.65 mg/kg, respectively). Among the three strains examined, CD-1 was the most sensitive to haloperidol's suppression of licking, while its sensitivity to clozapine's lick-suppressing effect was similar to C57BL/6 mice. Clozapine lowered the lick peak force in the CD-1 and BALB/c strains more than in the C57BL/6 strain. CONCLUSIONS: Overall, the results suggest that genetic variables may influence both mice's tongue dynamics and their alteration by both typical and atypical antipsychotic drugs. In addition, while the BALB/c strain was more sensitive to haloperidol's lick-disruptive effects than the C57BL/6 strain, the size of the difference between strains was much smaller than the reported difference between the strains in the catalepsy test.

Animals↗
PubMed1999

A field test of the quotient method for predicting risk to Microtus canicaudus in grasslands.

We used gray-tailed voles, Microtus canicaudus, as an experimental model species to field test a prediction of the Quotient Method (QM) for risk to small mammals of an insecticide in grasslands. In May 1997, we placed voles into 12 0.2-ha enclosures planted with a mixture of pasture grasses. In late July, we applied 1.55 kg/ha of the insecticide Guthion(R) 2S (azinphos-methyl) in three treatments: a control (all habitat sprayed with water), full spray (all of the habitat sprayed with Guthion 2S), and half-spray (one-half of the habitat sprayed with Guthion 2S and one half with water). Five replicates were used for the half-spray and control, and two replicates for the full-spray. The Guthion 2S treatment did not depress population size, growth rate, or survival of voles in half-spray or full-spray enclosures. Our results were inconsistent with the QM prediction for use of Guthion 2S in grass habitats. These results also differed from our previous studies in alfalfa habitats in which measurable responses were detected at the same application rate. The differences probably are due to the different types of vegetation between current and previous studies. The grass habitat in our enclosures was an average of 60 cm high and was very thick from ground level to about 40 cm. Much of the residue likely accumulated in the upper strata of vegetation and did not reach ground level at this application rate. Under the conditions of this study, voles were less affected in grassland habitat than they were in alfalfa habitat.

Animals↗
PubMed1999

Absence of brain-derived neurotrophic factor and trkB receptor immunoreactivity in glia of Alzheimer's disease.

Alterations in the neuronal expression of some neurotrophins have been shown in various neurodegenerative processes, particularly Alzheimer's disease (AD). Glia may up-regulate neurotrophins and their high-affinity tyrosine kinase (trk) receptors in response to neural injury. In human immunodeficiency virus type 1 (HIV-1) encephalitis, activated microglia were shown to express brain-derived neurotrophic factor (BDNF), while reactive astrocytes expressed trkB receptor. This observation has suggested the existence of local neurotrophic regulation between different glial populations. To characterize the glial cellular distribution of BDNF and trkB receptor proteins in AD, we studied selected regions of postmortem brains from four AD and three age-matched control patients by double-immunofluorescence confocal microscopy. In both groups, BDNF immunoreactivity was distributed in neuronal perikarya and neuritic processes in the neocortex and hippocampus. No BDNF immunoreactivity was observed in microglia or astrocytes within and between senile plaques of AD. Catalytic trkB receptor immunoreactivity was present in neuronal perikarya in the neocortex and hippocampus. Reactive astrocytes and microglia were not immunoreactive for catalytic trkB. The absence of BDNF and trkB proteins in glia in AD patients is in contrast to the finding in patients with HIV-1 encephalitis. This difference suggests that glial expression of BDNF and trkB proteins may be characteristic of particular disease processes, rather than merely representing a stereotyped response to any type of neural injury.

Aged↗
PubMed1999

Does thin filament compliance diminish the cross-bridge kinetics? A study in rabbit psoas fibers.

The effect of thin filament compliance on our ability to detect the cross-bridge kinetics was examined. Our experiment is based on the facts that in rabbit psoas the thin filament (1.12 micrometer) is longer than half the thick filament length (0.82 micrometer) and that the thick filament has a central bare zone (0.16 micrometer). Consequently, when sarcomere length is increased from 2.1 to 2.4 micrometer, the same number of cross-bridges is involved in force generation but extra series compliance is introduced in the I-band. Three apparent rate constants (2pia, 2pib, and 2pic) were characterized by sinusoidal analysis at pCa 4.66. Our results demonstrate that 2pia and 2pib increased 13-16% when sarcomere length was increased from 2.0 to 2.5 micrometer, and 2pic decreased slightly (9%). This slight decrease can be explained by compression of the lattice spacing. These observations are at variance with the expectation based on increased series compliance, which predicts that the rate constants will decrease. We also determined compliance of the I-band during rigor. I-band compliance during rigor induction was 35% of sarcomere compliance at sarcomere length 2.4 micrometer, and 24% at sarcomere length 2.1 micrometer. We conclude that the presence of thin filament compliance does not seriously interfere with our ability to detect cross-bridge kinetics using sinusoidal analysis.

Animals↗
PubMed1999

Differentiation of Neospora hughesi from Neospora caninum based on their immunodominant surface antigen, SAG1 and SRS2.

Neospora hughesi is a newly recognised parasite that is closely related to Neospora caninum, and is a cause of equine protozoal myeloencephalitis. We have characterised two N. hughesi immunodominant tachyzoite antigens which exhibit antigenic and molecular differences from the homologous tachyzoite antigens on N. caninum. These antigens on N. hughesi are referred to as NhSAG1 and NhSRS2, using the same mnemonics as used for the N. caninum antigens (NcSAG1 and NcSRS2), and are homologous to Toxoplasma gondii surface antigen 1 (SAG1) and SAG1-related sequence 2 (SRS2). The NcSAG1 and NcSRS2 were antigenically conserved in six different N. caninum isolates from cattle and dogs. The two equine-derived Neospora isolates, one designated as N. hughesi, were similar to each other but different from N. caninum. There was 6% difference in amino acid identity between NcSAG1 and NhSAG1, whereas there was a 9% difference when NcSRS2 and NhSRS2 were compared. The polymorphism of these genes and their corresponding proteins provide additional markers which can be used to distinguish N. caninum from N. hughesi.

Amino Acid Sequence↗
PubMed1999

HIV-associated Waldeyer's ring lymphoid hyperplasias: characterization of multinucleated giant cells and the role of Epstein-Barr virus.

Lymphoid hyperplasia of Waldeyer's ring (WR) is an often-symptomatic complication of human immunodeficiency virus (HIV) infection. A characteristic but not well explained finding is the presence of multinucleated giant cells (MNGCs) adjacent to crypt or surface epithelium. To further elucidate the MNGCs and assess their relationship to HIV and Epstein-Barr virus (EBV), 12 specimens from 11 HIV-positive patients were stained with antibodies to HIV-1 p24, EBV (latent membrane protein, LMP-1), histiocytes (CD68), and other antigen-presenting cells: S-100 protein, the Langerhans cell (LC) marker CD1a, and the follicular dendritic cell (FDC) marker (CD21). Double immunofluorescent staining to assess co-expression of p24 and cell-specific markers was performed and analyzed by laser-scanning confocal microscopy with 3-dimensional reconstruction. In situ hybridization for EBV-encoded small RNA (EBER) was performed in all cases. Immunostains showed MNGCs labeled for p24, S-100, and CD68, but not CD1a. In 1 case, rare MNGCs were CD21-positive. EBV LMP-1 was uniformly negative, although EBER-positive lymphocytes were seen by in situ hybridization in 9 of 12 specimens (numerous in only 3 specimens). Double immunofluorescent staining showed co-localization of p24 with CD68 and S-100. Our results suggest that MNGCs are generally HIV-infected, EBV-negative, and most likely represent an unusual S-100-positive histiocyte subset (not LC or FDC). Their exact pathophysiologic role remains uncertain. EBV does not appear to play a major role in the pathogenesis of WR lymphoid hyperplasias in HIV infection.

Adult↗
PubMed1999

Distribution of nifedipine- and omega-conotoxin GVIA-sensitive Ca2+ channels in cultured rat neocortical neurons.

L- and N-type voltage-dependent calcium channels are widely distributed in neurons of the CNS. To investigate their subcellular distributions on CNS neurons, intracellular calcium concentration ([Ca2+]i) increase in response to high potassium ([K+]) solution was detected in primary cultured rat neocortical neurons using the calcium indicator dye Oregon Green with a confocal laser scanning microscope. Extracellular application of 90 mM [K+] solution induced fluorescence increase in a manner dependent on extracellular [Ca2+]. The increase was partially blocked by 10 microM nifedipine, and the reduction was higher in cell bodies compared to dendritic processes. In contrast, omega-conotoxin GVIA reduced the 90 mM [K+] induced fluorescence increase more in the dendritic processes. The results demonstrated the heterogeneous distribution of nifedipine- and omega-conotoxin GVIA-sensitive calcium channels, which may suggest a functional difference in nifedipine- and omega-conotoxin GVIA-sensitive channels in cultured neocortical neurons.

Algorithms↗
PubMed1999

Mutation as an origin of genetic variability in Helicobacter pylori.

The availability of two complete Helicobacter pylori genome sequences and recent studies of its population genetics have provided a detailed picture of genetic diversity in this important human gastric pathogen. It is believed that, in addition to genetic recombination, de novo mutation could have a role in generating the high level of genetic variation in H. pylori.

DNA Damage↗
PubMed1999

Straightening the colon with curved cross sections: an approach to CT colonography.

RATIONALE AND OBJECTIVES: The purpose of this study was to straighten digitally and consistently the colon with curved cross sections and to compare the results with planar cross-section-based processing for computed tomographic (CT) colonography. MATERIALS AND METHODS: In electric field-based straightening, curved cross sections are formed along electric force lines because of electric charges digitally distributed along the colon central path. Four straightening experiments were conducted on CT scans of a colonoscopy phantom. Representative images were studied for polyp detectability and feature distortion. Two further trials involved patient data to demonstrate the clinical feasibility of this method. RESULTS: In colon straightening with planar sections, a polyp was counted multiple times in both phantom and patient studies where the polyps were in central path turns with substantial curvature. Furthermore, opposite the central path turns, the colon walls were undersampled with planar sections. Straightening with curved sections produced consistent mappings. Image distortion was present in straightening with curved sections, but the conspicuity of polyps was maintained. In the soft-straightening process, trilinear interpolation greatly suppressed the surface- or volume-rendering noise associated with nearest neighbor interpolation. CONCLUSION: Straightening with curved sections outperforms straightening with planar sections in terms of polyp detectability. This approach eliminates the navigation difficulties of current CT colonography and may have clinical use.

Colon↗
PubMed1999

Interpolation algorithms for digital mammography systems with multiple detectors.

RATIONALE AND OBJECTIVES: In some full-field digital mammography systems, multiple detectors are abutted together, and the physical gaps between adjacent detectors produce seams between the resultant subimages. In this study, a variety of interpolation algorithms for estimating the missing information in the seams were compared, and their effect on image quality was evaluated. MATERIALS AND METHODS: Eight representative interpolation algorithms were selected, including nearest neighbor, one-dimensional and two-dimensional weighting, mean value, one-dimensional and two-dimensional polynomial, and one-dimensional and two-dimensional cubic spline interpolation methods. These methods were applied to digital mammograms and phantom images. The effectiveness of each algorithm was evaluated for accuracy and geometric distortion. RESULTS: These interpolation algorithms offered similar accuracy in estimating missing image information. The weighting, polynomial, and cubic spline interpolation algorithms introduced less geometric distortion than the nearest neighbor and mean value interpolation algorithms. All algorithms were more effective in estimating larger, lower-contrast features (such as breast masses) than in estimating smaller, higher-contrast features (such as breast microcalcifications). Small microcalcifications within the seams cannot be recovered with interpolation. The probability of a microcalcification in a seam is small, however, and the failure to image a few microcalcifications of a cluster generally does not substantially alter diagnostic performance. CONCLUSION: In the development of full-field digital breast imaging systems, appropriate interpolation algorithms can satisfactorily fill in narrow gaps between adjacent detectors. The one-dimensional weighting interpolation method seems an effective and efficient choice.

Algorithms↗
PubMed1999

Iterative X-ray Cone-Beam Tomography for Metal Artifact Reduction and Local Region Reconstruction.

: X-ray cone-beam reconstruction from incomplete projection data has important practical applications, especially in microtomography. We developed expectation maximization (EM)-type and algebraic reconstruction technique (ART)-type iterative cone-beam reconstruction algorithms for metal artifact reduction and local reconstruction from truncated data. These iterative algorithms are adapted from the emission computerized tomography (CT) EM formula and the ART. A key step in our iterative algorithms is introduction of a projection mask and computation of a 3-D spatially varying relaxation factor that allows compensation for beam divergence and data incompleteness. The algorithms are simulated with projection data synthesized from mathematical phantoms. In simulation, the EM-type and ART-type iterative algorithms are demonstrated to be effective for metal artifact reduction and local region reconstruction. They perform similarly in terms of visual quality, image noise, and discrepancy between measured and reprojected data. The EM-type and ART-type iterative cone-beam reconstruction algorithms have potential for metal artifact reduction and local region reconstruction in X-ray CT.

Journal Article↗
PubMed1999

Development of a 96-well enzyme-linked solid-phase assay for beta-glucanase and xylanase.

An enzyme-linked sorbent assay (ELSA) for estimating beta-glucanase activity was developed on the basis of the use of biotinylated beta-glucan as a solid-phase substrate. The assay involves the coating of titer plate wells with biotinylated beta-glucan, the partial hydrolysis of this substrate with beta-glucanase, the reaction of the biotin from the unhydrolyzed substrate with an alkaline phosphatase-streptavidin complex, and quantitation of the remaining beta-glucan using alkaline phosphatase. The activity of the bound indicator enzyme, alkaline phosphatase, is proportionally related to the beta-glucanase activity in the sample. The ELSA is simple, can be readily adapted to the routine assay of a large number of samples (as many as 200 per person/day), and has good precision (CV = 4.0-6.4%) and high sensitivity (detects as low as 0. 001 mU of beta-glucanase/assay). A similar assay was developed for xylanase using biotinylated arabinoxylan. The ELSA provides a simple and sensitive estimate of beta-glucanase and xylanase activity.

Biotinylation↗