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Biomedical subjects

C Xia

Publications and source records attributed to C Xia.

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

[Spectrophotometric determination of trace copper in electroplating wastewater].

In the presence of CPB and OP, the chromogenic reaction of DBH-PF with Cu(II) was studied. The results show that the purple micelle reaction has high sensitivity in the medium of (CH2)6N4-HCl(pH = 5.4) buffered solution, the molar absorptivity is 1.8 x 10(5) L.mol-1.cm-1, and Beer's law is obeyed for Cu(II) in the range of 0.0-9.0 micrograms.25 mL-1 at 540 nm. Combined with solvent extraction separation, the method has been applied to the determination of trace Cu in electroplating wastewater with satisfactory results.

Copper↗
PubMed2001

[Determination of trace manganese in coal gangue by catalytic spectrophotometry].

In HAc-NaAc solution trace Mn(II) catalyzes strongly decolorization reaction of bright green SF(BGSF) by oxidizing with potassium periodate and its catalytic extent is linear with the contents of Mn(II) in the certain range. Based on this study, a catalysis spectrophotometric method for determining trace Mn(II) was developed. The results show that the maximum absorption of the complex is at 651 nm and the detection limits of the method is 0.060 microgram.L-1 for Mn(II) and Beer's law is obeyed for Mn(II) in the range of 0.03-0.3 microgram.50 mL-1. The method has been applied to the determination of trace Mn in coal gangue with satisfactory results.

English Abstract↗
PubMed2000

GCIP, a novel human grap2 and cyclin D interacting protein, regulates E2F-mediated transcriptional activity.

Regulation of mammalian cell growth and proliferation is governed through receptor-mediated signaling networks that ultimately converge on the cell cycle machinery. Adaptor proteins play essential roles in the formation of intracellular signaling complexes, relaying extracellular signals from the plasma membrane to the nucleus of a cell. The leukocyte-specific adaptor protein Grap2 is a central linker protein in immune cell signaling and activation. Using Grap2 as bait protein, we identified a novel human protein, GCIP (Grap2 cyclin-D interacting protein). We found that GCIP bound to Grap2 in both yeast two-hybrid assays and in mammalian cells through binding to the COOH-terminal unique domain and SH3 domain (designated QC domain) of Grap2. GCIP also associated with cyclin D both in vitro and in vivo. The expression of GCIP was found in all human tissues examined with the highest level of expression in the heart, muscle, peripheral blood leukocytes, and brain. Furthermore, phosphorylation of retinoblastoma protein by cyclin D-dependent protein kinase was reduced and E2F1-mediated transcription activity was inhibited in cells transfected with GCIP. High level expression of GCIP in terminally differentiated tissues and the inhibition of E2F1 transcription activation suggest that GCIP could play an important role in controlling cell differentiation and proliferation.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Wild type ApoA-II gene does not rescue senescence-accelerated mouse (SAMP1) from short life span and accelerated mortality.

Biochemical and genetic data suggest that the Apoa2c allele of the apolipoprotein A-II gene causes severe senile amyloidosis (AApoAII) in SAMP1, a mouse model for accelerated senescence. We analyzed the effects of replacement of Apoa2c in SAMP1 mice with non-amyloidogenic Apoa2b on amyloidosis, lipoprotein metabolism, and progression of senescence using a congenic strain, P1.R1-Apoa2b, which has the Apoa2b chromosome region of SAMR1 in the genome of SAMP1. Age-associated amyloid deposition was not observed, but plasma concentrations of apoA-II protein and HDL-cholesterol decreased with age in P1.R1-Apoa2b. P1.R1-Apoa2b showed lower scores of senescence than did SAMP1. However, the life span and mortality rate doubling time were similar in P1.R1-Apoa2b and SAMP1. These results suggest that replacement of Apoa2c with non-amyloidogenic Apoa2b does not rescue SAMP1 mice from a short life span and accelerated mortality.

Aging↗
PubMed2000

Nuclear volume estimation using different sampling, measurement and calculation methods.

OBJECTIVE: To study the reliability of volume parameter measured on tissue sections through different sampling, measurement and calculation methods. STUDY DESIGN: The largest nuclear profile image under a 100x, NA 1.30 oil immersion objective of primary spermatocytes and spherical spermatoblasts on 11-micron-thick seminiferous tubule sections and tissue images, under a 20x objective, on 4-micron sections were captured. Their volumes were measured and calculated by the five methods provided by the Technology for Image and Graphics Engineering Research cell image analysis system. RESULTS: The nuclear volumes obtained by nucleator and area equivalent diameter on the largest nuclear profile image were almost the same, including binary images by automated and manual interactive nucleator and grey scale images only by the latter. Nuclear volumes, calculated by random Feret diameter and equivalent diameter of the perimeter, the minimal circumference of the largest nuclear profile binary image, were obviously larger than those of the nucleator and area equivalent diameter. Due to different-sized nuclear slices entrapped in the same section, those nuclear volumes from the seminiferous tubule tissue images were strikingly lower than that of the largest nuclei profile image. The shape factors of primary spermatocytes and spherical spermatoblast nuclei under 100x and 20x objectives were approximately the same. CONCLUSION: The sample preparation, sampling methods and calculation formulas suitable to nuclear form are necessary to obtain reproducible volume parameters.

Animals↗
PubMed2000

[Effect of urotensin II on the airway smooth muscle cell proliferation and its mechanism].

OBJECTIVE: To investigate the effect and mechanism of Urotensin II on the airway smooth muscle cell proliferation. METHODS: (1) Using 3H-TdR incorporation to determine the effect of Urotensin II on the rat airway smooth muscle cells DNA synthesis. Different inhibitors were used to study the role of different signal transduction pathway such as protein kinase C (PKC), mitogen-activated protein kinase (MAPK), Calcineurin (CaN), Calmodulin-dependent protein kinase (CaM-PK) and calcium channel in the mitogenic effect of Urotensin II on the airway smooth muscle cells. (2) Using Fura-2/AM to measure the effect of Urotensin II on the cytosolic free calcium concentration. RESULTS: (1) Urotensin II (10(-10)-10(-6) mol/L) increased the airway smooth muscle cell 3H-TdR incorporation in a dose-dependent manner and Urotensin II 10(-6) mol/L reached the maximal effect. It was seven times as high as that of control (P < 0.01). (2) H7, PD98059, and nicardipine, inhibitors of PKC, MAPK and calcium channel, significantly inhibited Urotensin II (10(-7) mol/L)-stimulated airway smooth muscle cell 3H-TdR incorporation, with the inhibitory rate of 29% (P < 0.05), 45% (P < 0.01), and 28% respectively (P < 0.05). W7, an inhibitor of CaM-PK, had no effect (P > 0.05). (3) Cyclosporin A (10(-8)-10(-6) mol/L), inhibitor of CaN, an inhibited the airway smooth muscle cell 3H-TdR incorporation induced by Urotensin II (10(-7) mol/L) in a dose-dependent manner, with the inhibitory rate of 76% at 10(-6) mol/L (P < 0.01). (4) Urotensin II (10(-6) mol/L) promoted cytosolic free calcium concentration increase by 18% (P < 0.01). CONCLUSION: The effect of Urotensin II-stimulated airway smooth muscle cells DNA synthesis is mediated by Ca2+, PKC, MAPK and CaN signal transduction pathway.

Animals↗
PubMed1999

Specific cell-mediated immunity in fish.

This review describes the fish immune system, focusing on specific cell-mediated immunity. Specific in vivo cell-mediated immune responses have been shown by allograft rejection, graft-versus-host reaction (GVHR) and delayed hypersensitivity reaction (DTH). Recent in vitro studies also showed specific cell-mediated cytotoxicity against allogeneic target cells. These in vivo and in vitro experiments strongly suggest the presence of cytotoxic T cells in fishes. Also described are current studies on shark and trout MHC class I polymorphism and function that demonstrate strong similarities between fish and mammals.

Animals↗
PubMed1999

Identification of peak bone mass QTL in a spontaneously osteoporotic mouse strain.

The whole genome scan for quantitative trait loci (QTLs) specifying peak bone mass was performed with the F2 intercrosses of SAMP6, an established murine model of senile osteoporosis, exhibiting a significantly lower peak bone mass, and SAMP2, exhibiting a higher peak bone mass. Cortical thickness index (CTI), a parameter of bone mass of femurs, was measured in 488 F2 progeny at 4 months of age, when the animals attained peak bone mass by microphotodensitometry. Genetic markers were typed at 90 loci spanning all chromosomes except the Y. By interval mapping of 246 male F2 mice, two loci were identified with significant linkage to peak bone mass, one on Chromosome (Chr) 11 and another on Chr 13, with a maximum lod score of 10.8 (22.2% of the total variance) and 5.8 (10.0%), respectively. Another locus on the X Chr was suggestive of a QTL associated oppositely with a low peak bone mass to the SAMP2 allele. This association was consistent with the distribution of peak bone mass in the F1 and F2. These findings should be useful to elucidate the genetics of osteoporosis.

Animals↗
PubMed1999

Genetic typing of the senescence-accelerated mouse (SAM) strains with microsatellite markers.

The Senescence-Accelerated Mouse (SAM) strains constitute a murine model of accelerated senescence originating from the ancestral AKR/J strains and consist of nine senescence-prone (SAMP) strains and four senescence-resistant (SAMR) strains. The chromosomes (Chrs) of the SAM strains were typed with 581 microsatellite markers amplified by PCR, and the fundamental genetic information of the SAM strains was obtained. One-third of the examined markers displayed polymorphism among the strains, and only two alleles were detected in almost all loci among the SAM and AKR/J strains. However, in 12 loci (5.6% of total 215 polymorphic markers), the third allele was detected among the SAM strains. The genetic typing and developmental history suggested that the SAM strains were related inbred strains developed by the accidental crossing between the AKR/J strain and other unknown strain(s). Comparison of the distribution of the loci in the SAMP and the SAMR series revealed notable differences in the four regions on Chrs 4, 14, 16, and 17. This indicated that some of these chromosomal sites might contain the genes responsible for accelerated senescence in the SAMP series.

Aging↗
PubMed1999

Mouse senile amyloid deposition is suppressed by adenovirus-mediated overexpression of amyloid-resistant apolipoprotein A-II.

Apolipoprotein A-II (apoA-II), the second most abundant apolipoprotein of serum high density lipoprotein, deposits as an amyloid fibril (AApoAII) in old mice. Mouse strains with a high incidence of senile amyloidosis have the type C apoA-II gene (Apoa2(c)), whereas the strains with a low incidence of amyloidosis have the type B apoA-II gene (Apoa2(b)). In this study, to investigate whether the type B apoA-II protein inhibits the extension of amyloid fibrils, we constructed an adenovirus vector bearing the Apoa2(b) cDNA (Adex1CATApoa2(b)), which is expressed under the control of a hepatocyte-specific promoter. The mice were infected with Adex1CATApoa2(b) before induction of amyloidosis by the injection of AApoAII amyloid fibril seeds. Compared with the mice infected with the control virus, amyloid deposition was suppressed significantly in the mice infected with Adex1CATApoa2(b). Fluorometry using thioflavine T also revealed that AApoAII fibril extension was inhibited by the addition of type B apoA-II in vitro. Thus, we propose that Apoa2(b) contributes as an active inhibitor of amyloid fibril extension and overexpression of amyloid-resistant gene variant may be an attractive therapeutic target in amyloidosis.

Adenoviridae↗
PubMed1999

[The expressions of Fas and Fas-L in human breast invasive ductal carcinomas and their surrounding tissues].

OBJECTIVE: To study the relationship of the expression of Fas and Fas-L with the pathogenesis and differentiation of breast invasive ductal carcinomas. METHODS: Both carcinoma tissues and their surrounding tissues from 50 patients with breast invasive ductal carcinomas were studied for the expression of Fas and Fas-L by immunohistochemical staining. RESULTS: The expression level of Fas in breast ductal carcinoma was significantly lower than that of tissues surrounding carcinomas, and the expression level of Fas-L in breast ductal carcinoma was significantly higher than that of tissues surrounding carcinomas. There was no significant difference in the expression of Fas and Fas-L in carcinomas with different differentiation grades. CONCLUSIONS: The expression of Fas is downregulated and the expression of Fas-L is upregulated in human breast invasive ductal carcinomas. Human breast invasive ductal carcinomas may enhance their development through downregulating the expression of Fas and upregulating the expression of Fas-L. The expression level of Fas and Fas-L has nothing to do with the differentiation of human breast invasive ductal carcinomas.

Breast Neoplasms↗
PubMed1999

[Measurement of strength of thigh muscles through arthroscope after reconstruction of anterior cruciate ligament].

OBJECTIVE: To observe the strength of thigh muscles after reconstruction of anterior cruciate ligament by autogenous bone-patellar tendon-bone graft. METHODS: Twenty-three patients, 9 males and 14 females, were followed up one year after reconstruction of the anterior cruciate ligament with autogenous bone-patellar tendon-bone graft. Through arthroscope, no intra-articular derangement was found. The strengths of isometric and isotonic contractions of the quadri ceps and the hamstrings muscles of the affected and contralateral thighs were recorded. RESULTS: The donor side for autogenous bone-patellar tendon-bone graft showed significant decrease (P < 0.01), but no effect on that of the hamstrings muscle(P > 0.05). CONCLUSION: To reconstruct the anterior cruciate ligament, harvest of the bone-patellar tendon-bone graft as a reparative material may markedly lower the strength of the quadriceps femoris muscle.

Adolescent↗
PubMed1999

[Gas chromatography-infrared spectroscopy(GC-IR) analysis of the oxidation products of cyclohexene].

Gas chromatography-infrared spectroscopy technique integrates the excellent resolution ability of GC with the structural information of IR. Based on the GC and IR spectra, the complicated products of a reaction can be analyzed quantitatively and qualitatively. From the analysis of the products, the reaction process and its mechanism can be elucidated. In this work, analysis by GC-IR of the oxidation products of cyclohexene catalyzed by zeolite TS-1 in H2O2 was performed. The products are 2-cyclohexenone, 2-cyclohexen-1-ol and 2,3-epoxy-1-cyclohexanone. 2,3-Epoxy-1-cyclohexanone is an unexpected product. It must be a further oxidation product of 2-cyclohexenone. From the analysis, the reaction mechanisms were presumed.

Alkanes↗
PubMed1999

[Detection of hypodermal and hematopoietic necrosis baculovirus by PCR method].

For control of the explosive epidemic disease of Penaeid shrimp in China. We have developed a method for detection of Hypodermal and hematopoietic necrosis baculovirus (HHNBV) by polymerase chain reaction (PCR). Two pairs of PCR primers (DP1/DP2 and DP3/DP4) were prepared, based on the RFLP analysis between HHNBV and penaeid rod-shaped DNA virus. PCR using either DP1/DP2 or DP3/DP4 specified HHNBV genome. When PCR products amplified with DP1/DP2 were subjected to nested PCR with DP3/DP4, a high sensitivity about 0.04 pg was seem with the nested PCR.

Animals↗
PubMed1999

[A preliminary study of two Chinese herbs protective tablets on some Chinese traditional medicines].

The protective action of 2 tablets of Chinese herb to 5 Chinese traditional medicines against harm of insects and mildews was tested. It was found that 2 tablets have a obvious effects of insect-repellency and mouthproof in the test with Homalomena occulta and Prunus armeniaca, the bore in the medicinal materials was decreased 94.95% and 95.55% respectively than that of check. The tablets have some effects of mildewproof in the test with Tussilago farfara.

Alisma↗
PubMed1998

Diode Laser Spectroscopy of the nu1 and nu3 Bands of SD+3

The nu1 and nu3 bands of SD+3 were observed at 5.45 µm with a diode laser spectrometer. The ions were generated in a concentration-modulated, low-temperature, hollow-cathode discharge of deuterium and carbonyl sulfide gases. One hundred and ninety-two lines were measured and assigned to SD+3. The majority of these lines were assigned to the nu3 perpendicular band with 49 lines assigned to the nu1 parallel band. A simultaneous fit of these bands provided the first experimental parameters for the SD+3 ion. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Effects of oxygen on 3-hydroxyanthranilate oxidase of the kynurenine pathway.

Iron containing 3-Hydroxyanthranilate oxidase (3HAO) converts 3-hydroxyanthranilate (3HAA) and dioxygen into a precursor which spontaneously converts to quinolinic acid (QA). 3HAO participates in de novo biosynthesis of NAD in mammalian kidney and liver, and it is present in low concentrations in brain where its function is controversial. However, QA increases in spinal fluid and is associated with convulsions in AIDS dementia, Huntington's disease, and CNS inflammation. QA is a known N-methyl, D-aspartate receptor agonist and excitotoxin that causes convulsions when injected into the brain. Hyperbaric oxygen (HBO) also causes convulsions and we investigated the interrelationships among the stimulating and toxic effects of oxygen and the role of iron in vitro using rat liver enzyme which is reported to be identical to brain enzyme and is more abundant. 3HAO requires dioxygen as a substrate but it was inactivated approximately 40% by 5.2 atm HBO in vitro in 15 min. The apparent Km was 2.6 x 10(-4) M for oxygen and 5 x 10(-5) M for 3HAA, and these values did not change for enzyme that was half-inactivated by HBO oxygen. Thus, oxygen-inactivation appears to be all-or-none for individual enzyme molecules. Freshly prepared enzyme was activated about 3-fold by incubation with acidic iron. Iron-staining of 3HAO, separated by gel electrophoresis after partial purification by FPLC, showed that loss of iron and loss of enzyme activity during HBO exposure were correlated. The apparent oxygen Km of 3HAO is far higher than the oxygen concentration in brain cells. Thus, 3HAO is capable of being stimulated initially in animals breathing HBO, and subsequently of being inactivated with potential significance for brain QA and convulsions.

3-Hydroxyanthranilic Acid↗