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Biomedical subjects

X Guo

Publications and source records attributed to X Guo.

At least 163 records · Page 9Linked to original sources
PubMed2000

PCR detection of Salmonella enterica serotype Montevideo in and on raw tomatoes using primers derived from hilA.

Salmonellae have been some of the most frequently reported etiological agents in fresh-produce-associated outbreaks of human infections in recent years. PCR assays using four innovative pairs of primers derived from hilA and sirA, positive regulators of Salmonella invasive genes, were developed to identify Salmonella enterica serotype Montevideo on and in tomatoes. Based on examination of 83 Salmonella strains and 22 non-Salmonella strains, we concluded that a pair of hilA primers detects Salmonella specifically. The detection limits of the PCR assay were 10(1) and 10(0) CFU/ml after enrichment at 37 degrees C for 6 and 9 h, respectively. When the assay was validated by detecting S. enterica serotype Montevideo in and on artificially inoculated tomatoes, 10(2) and 10(1) CFU/g were detected, respectively, after enrichment for 6 h at 37 degrees C. Our results suggest that the hilA-based PCR assay is sensitive and specific, and can be used for rapid detection of Salmonellae in or on fresh produce.

Bacterial Proteins↗
PubMed2000

Heritability of angiotensin-converting enzyme and angiotensinogen: A comparison of US blacks and Nigerians.

Angiotensinogen (AGT) and angiotensin I-converting enzyme (ACE) are heritable traits, but whether the environmental context influences heritability has not been examined. Known genetic factors explain only a portion of variation in AGT and ACE, and levels of both proteins are influenced by the environment. The African diaspora provides an opportunity to compare these traits in genetically related populations in contrasting environments. As part of a study of the genetics of hypertension, we examined families that included 1449 Nigerians and 1147 African Americans. Body mass index (weight [kg]/height [m](2)) was 21 kg/m(2) in Nigeria and 29 kg/m(2) in the United States, which is consistent with a large environmental contrast. AGT was considerably higher among African Americans (1919 versus 1396, P<0.01), whereas ACE was higher in Nigerians (630 versus 517, P<0.01). A household effect was observed among the Nigerian families (spouse correlations 0.30 for AGT, 0.18 for ACE), and correlations among first-degree relatives were large (0.42 to 0. 51 and 0.36 to 0.38 for AGT and ACE, respectively). Among African Americans, the familial aggregations of AGT and ACE were very limited, and the familial correlation for AGT was not different from zero. Heritability was 77% for AGT and 67% for ACE in Nigeria and 18% for AGT and ACE in the United States. The familial patterns of body mass index and blood pressure were similar among both family sets. In conclusion, less familial aggregation was observed for AGT and ACE in the United States than in Nigeria, most likely reflecting a greater random individual environmental effect on these traits. Variation in heritability of traits could influence the power of epidemiological studies to identify genetic effects.

Adult↗
PubMed2000

Topography of ganglion cells in the retina of the horse.

Topography of ganglion cells in the retina of the horse (Thoroughbred) was analyzed in the wholemount retina stained with cresyl violet, and a total number of ganglion cells were estimated. Sizes of ganglion cells were also measured and size spectra were analysed. The main results showed that: (1) a common point in 4 wholemount retinae, based on cell densities and retinal locations, was that a retina could be divided into 5 regions, namely visual streak, nasal, temporal, dorsal and ventral region to the visual streak. A maximum cell density of 4,000 cells/mm2 was found in the visual streak. And a total number of ganglion cells was estimated in a range of 398 x 10(3) - 469 x 10(3), with a mean of 441 x 10(3) +/- 31 x 10(3) (n=4). (2) cell sizes were measured as the mean lengths of the major and minor axes of the somas, and were in a range of 5-53.8 microm. The lowest mean diameter was 14.0 microm (+/- 3.7) in the visual streak and the highest was 25.9 microm (+/- 7.6) in the ventral region. Cell size spectra were unimodal and positively skewed. It is expected that these analyses will provide an anatomical and physiological background for further study of the visual system in the horse.

Animals↗
PubMed2000

Generalized low areal and volumetric bone mineral density in adolescent idiopathic scoliosis.

Adolescent idiopathic scoliosis (AIS) may be associated with generalized low bone mineral status. The bone mineral density (BMD) of 75 girls of 12-14 years of age and diagnosed as having AIS were compared with 94 age-matched female control subjects. Areal BMD (aBMD) of the lumbar spine (L2-L4) and the bilateral proximal femur were measured using-energy X-ray absorptiometry (DEXA), and volumetric BMD (vBMD) of the nondominant distal radius and bilateral distal tibias was measured with peripheral quantitative computer tomography (pQCT). Relevant anthropometric parameters and the severity of the spinal deformity (Cobb's angle) also were evaluated and correlated with the BMD measurements. Results revealed the presence of a generalized lower bone mineral status in AIS patients. Detailed analysis showed that the aBMD and vBMD measured at the bilateral lower extremities were significantly lower in AIS patients when compared with the same in the normal controls. The most significant effect was seen in the trabecular BMD (tBMD) of the distal tibias. Of all the AIS girls, 38% of the aBMD and 36% of the vBMD were below -1 SD of the normal. BMD was found to correlate better with "years since menarche" (YSM) than with chronological age. When the BMD was evaluated for the 3 YSM groups, aBMD of the proximal femur and tBMD of distal tibias were found to be significantly lower in the AIS patients. Neither the aBMD nor the vBMD of AIS patients was found to be associated with the severity of spinal deformity. In addition, anthropometric measurements showed significantly longer arm span and lower extremities in the AIS girls. We concluded that the AIS girls had generalized lower aBMDs and vBMDs.

Adolescent↗
PubMed2000

[Effect of lipoprotein lipase gene polymorphism on plasma lipid levels,BMI and subcutaneous fat distribution in simple obesity children].

OBJECTIVE: To assess the effect of Hind III DNA polymorphism in the lipoprotein lipase(LPL) gene on plasma lipid levels, body mass index(BMI) and subcutaneous fat distribution in simple obesity children. METHODS: The polymerase chain reaction(PCR) and restriction fragment length polymorphism(RFLP) techniques were used to detect the Hind III-LPL genotypes in 92 children with simple obesity. The levels of the plasma lipid, plasma lipoproteins, BMI and skinfold thickness at three measuring points(biceps, subscapular and abdominal wall) were also measured. RESULTS: The levels of TG, TC, LDL-C, Apo B, BMI, biceps and subscapular skinfold thickness with the average value of three measuring points in the obesity children with H(+) H(+)-LPL genotype were significantly higher than those in the obesity children with H(+) H(-)-LPL genotype. CONCLUSION: LPL-Hind III polymorphism may modify the levels of plasma lipid. plasma lipoproteins and BMI in children with simple obesity, and in the mean while it may affect the distribution of subcutaneous fat.

Body Mass Index↗
PubMed2000

E2F-1: a proliferative marker of breast neoplasia.

E2F-1 is the best known ultimate transcription factor in the cyclin/cyclin-dependent kinase/retinoblastoma gene pathway and is probably involved in carcinogenesis and tumor progression. Because E2F-1 can be detected in paraffin sections using immunohistochemical techniques, it could be a useful tumor/proliferation marker. We studied the expression of this gene product in 130 breast tissue specimens from 100 patients and compared it with the expression of Mib-1, the widely used prognostic/proliferative marker, to assess E2F-1 as a new marker of neoplastic proliferation. The percentage of E2F-1-positive cells increased from 1.9% in the normal breast (NB) to 6.3% in ductal carcinoma in situ (DCIS) and to 15.3% in invasive ductal carcinomas (IDC). In addition, higher-grade tumors as well as advanced-stage disease correlated with higher expression of E2F-1. A similar tendency of Mib-1 expression was observed. There was a positive correlation between the E2F-1 and Mib-1 indices. In an in vitro experiment, we found that a similar difference in the expression of E2F-1 existed between a nontumorigenic breast cell line and two widely used breast carcinoma cell lines. The breast carcinoma cell lines T-47D and MCF-7 had more E2F-1-positive cells than the nontumorigenic cell line MCF-10F by immunohistochemistry and Western blot analysis. Because E2F-1 expression was significantly higher in IDC and DCIS than in NB, this study indicates that deregulation of E2F-1 may be involved in the development of breast IDC. In addition, E2F-1 expression could also be involved in tumor progression because the increased E2F-1 index correlated with the known prognostic predictors of breast cancer, such as histological grade, stage, metastasis status, estrogen receptor/progesterone receptor and Mib-1 expression. Thus, E2F-1 is a promising candidate to become a new prognostic/predictive marker of breast cancer.

Adult↗
PubMed2000

Study on DNA polymorphism at D1S8 locus in Hebei Han population.

OBJECTIVE: To study the polymorphism at D1S8 locus and to provide basic information for the construction of DNA fingerprint database and the application in forensic medicine. METHODS: Minisatellite variant repeat-polymerase chain reaction (MVR-PCR) and polyacrylamide gradient gel electrophoresis followed by silver staining were used to detect the variant repeat sequences at D1S8 locus of 240 unrelated individuals in Hebei Han population, and digital codes were obtained. RESULTS: Each individual obtained about 30 digital codes, in which none of two unrelated individuals had the same code. The probability of identity of 30 digital codes was 3.55x10(-11). The percentages of three repeat units, a-type, t-type and o-type were 54.77%, 42.54% and 2.69% respectively. The heterozygosity (H) was 0.9837. The excluding probability of paternity(EPP) and polymorphism information content(PIC) were 0.9669 and 0.9833 respectively. CONCLUSION: Because of its high polymorphic nature, D1S8 locus is a valuable marker for forensic identification and paternity testing.

Chromosome Mapping↗
PubMed2000

The effect of burn injury on suppressors of cytokine signalling.

The newly identified suppressors of cytokine signaling (SOCS) family of proteins act as intracellular inhibitors of several cytokine signal transduction pathways. Their expression is induced by cytokine activation of the Janus kinase/signal transducer and activator of transcription (Jak/STAT) pathway, and they act as a negative feedback loop by subsequently inhibiting the Jak/STAT pathway either by direct interaction with activated Jaks or with the receptors. In this study we investigated the expression and translation of SOCS proteins after burn injury. Thermal injury increased the expression of SOCS3 compared with sham at 4 h, 24 h, and 10 days after thermal injury in the liver. SOCS3 protein was increased at 4 and 24 h after thermal injury in the liver. Expression of SOCS1 mRNA was not detected in sham or burn liver. SOCS2 mRNA and cytokine-inducible SH2-containing protein (CIS) mRNA were detected at the same levels for both sham and burn at all time points in the liver. In the spleen there was a trend towards an increase in SOCS1 mRNA at all time points; thermal injury significantly decreased SOCS2 mRNA compared with sham at 4 h, SOCS3 mRNA was significantly increased at 24 h compared with 10 days, and CIS mRNA was detected at the same levels for both sham and burn at all time points. In conclusion, thermal injury causes elevations in SOCS3 within 4 h after a burn, reaching a maximum at 24 h post injury. Levels continue to be elevated for up to 10 days post injury. SOCS3 may be very important in regulating the balance between immunosuppression and inflammation after thermal injury.

Animals↗
PubMed2000

High glucose enhances H2O2-induced apoptosis in bovine aortic endothelial cells.

AIM: To investigate the effect of high glucose on hydroperoxide (H2O2)-induced apoptosis in cultured bovine aortic endothelial cells (BAEC). METHODS: BAEC were cultured and passaged in normal glucose (5.5 mmol.L-1, NG) and high glucose (25 mmol.L-1, HG). Morphologic changes and quantification of apoptotic cells were determined under fluorescence microscope after H2O2-treated BAEC for 24 h with Hoechst 33258 staining. DNA fragmentation was visualized by agarose gel electrophoresis. The expression of phospho-p38 Ca(2+)-calmodulin dependent protein kinase (CCDPK, formerly called MAPK) was measured by Western blotting. RESULTS: H2O2 elicited typical apoptotic morphologic changes (chromatic condensation, nucleus fragmentation). At 100 -300 mumol.L-1, both NG- and HG-BAEC incubated with H2O2 for 24 h increased cell apoptosis and phospho-p38 CCDPK expression in a concentration-dependent manner. In HG-BAEC, H2O2 induced DNA fragmentation at a lower concentration than that in NG-BAEC, and the apoptotic cell count in HG-BAEC was also higher than that of NG-BAEC (P < 0.05). Similarly, the expression of phospho-p38 CCDPK induced by H2O2 was up-regulated in HG-BAEC (P < 0.05). CONCLUSION: High glucose enhances H2O2-induced apoptosis in BAEC, which is related to high expression of phospho-p38 CCDPK.

Animals↗
PubMed2000

High glucose impairs endothelium-dependent relaxation in rabbit aorta.

AIM: To study the effects of high glucose on endothelium-dependent relaxation (EDR) and the action of L-arginine, superoxide dismutase (SOD), or glucose re-normalization in aorta. METHODS: Measurement of EDR of the isolated rabbit thoracic aortic rings. RESULTS: Elevated glucose (25 mmol.L-1) caused profound impairment of acetylcholine (ACh)-induced relaxation, EC50: 1.6 mumol.L-1 (95% CL: 7.9 nmol.L(-1)-6.3 mumol.L-1) vs normal glucose (5.5 mmol.L-1) EC50: 0.08 mumol.L-1 (95% CL: 0.02 mumol.L(-1)-0.3 mumol.L-1) (P < 0.01), which not reversed followed by a further 24 h incubation in normal glucose M199, EC50: 2.0 mumol.L-1 (95% CL: 0.2 pmol.L(-1)-12.5 mumol.L-1). However, aortic rings incubated with mannitol (19.5 mmol.L-1) relaxed to ACh normally. L-arginine 1 mmol.L-1 or SOD 150 U.L-1 restored ACh relaxation in elevated glucose to normal, EC50: 0.16 mumol.L-1 (95% CL: 0.04 mumol.L(-1)-0.8 mumol.L-1) and 0.16 mumol.L-1 (95% CL: 0.03-0.63 mumol.L-1). The relaxation in response to sodium nitroprusside was not different between rings exposed to normal or elevated glucose. CONCLUSION: Hyperglycemia impaired EDR, which was not reversible by glucose re-normalization, increased free radical production and altered L-arginine metabolism were involved in this endothelium dysfunction.

Acetylcholine↗
PubMed2000

[A study of sleep apnea monitoring method and instrument].

In this paper the fundamental principle and great significance of sleep apnea monitoring are introduced, and the status quo of this field at home and abroad is described. Several kinds of methods for sleep apnea monitorin are analyzed, and on this basis the authors have developed a cheap and portable sleep apnea monitoring instrument. Experiment results demonstrate that the instrument is of convenience, high accuracy and good performance.

Adult↗
PubMed2000

Detection of interleukin-8 in exudates from normal and inflamed human dental pulp tissues.

OBJECTIVE: The purpose of this study was to investigate the level of IL-8 in exudates clinically obtained from normal and inflamed human dental pulp tissues so as to reveal the possible relationship between IL-8 and pulpitis. METHODS: Samples of 2 microliters of pulpal exudate from each normal or clinically diagnosed as acute or chronic pulpitis teeth was obtained by filter paper strips and IL-8 level was measured by ELISA method. RESULTS: No IL-8 was detected in the samples from normal pulp, but significant amount of IL-8 appeared in inflamed pulp tissues, and the level of IL-8 in exudates of acute stage of pulpitis was higher than that of chronic stage (P < 0.01). CONCLUSIONS: This study demonstrates that IL-8 is produced and accumulated in pulp inflammation and may play a role in the occurrence and development of human pulpitis.

Acute Disease↗
PubMed2000

High glucose inhibits expression of inducible and constitutive nitric oxide synthase in bovine aortic endothelial cells.

AIM: To investigate the effects of high glucose on the expression of nitric-oxide synthase (NOS) in cultured bovine aortic endothelial cells (BAEC). METHODS: BAEC were cultured and passaged in normal glucose (NG) 5.5 mmol.L-1, high glucose (HG) 25 mmol.L-1, or high osmolarity (glucose 5.5 mmol.L-1 + mannitol 19.5 mmol.L-1, Mann-BAEC), lipopolysaccharides (LPS)-induced nitric oxide (NO) production was assessed by Griess reaction. The expression of inducible NOS (iNOS) and constitutive NOS (ecNOS) was determined by Western blot. RESULTS: At a concentration range from 0.5 to 2 mg.L-1, LPS stimulated NO production in NG-BAEC in a concentration-dependent manner. NO production reached the peak level at LPS 1 mg.L-1. HG inhibited NO production, when compared with NG- and Mann-BAEC (nitrite mumol.L-1: HG-BAEC 43 +/- 8, vs NG-BAEC 71 +/- 11, Mann-BAEC 70 +/- 9, n = 4 experiments, P < 0.01). iNOS expression was decreased by 39.9% and 39.3%, and ecNOS by 28% and 24% respectively in HG-BAEC, when compared with NG- or Mann-BAEC. However, no marked difference was observed in the LPS-induced NO production and the expression of iNOS and ecNOS between NG- and Mann-BAEC. CONCLUSIONS: Inhibition of BAEC NO production by HG was mainly due to a decreased expression of NOS protein.

Animals↗
PubMed2000

Effects of p38 and p42/p44 CCDPK signaling on H2O2-induced apoptosis in bovine aortic endothelial cells.

AIM: To investigate the effects of p38 and p42/p44 Ca(2+)-calmodulin dependent protein kinases (CCDPK) signaling on hydroperoxide (H2O2)-induced apoptosis in cultured bovine aortic endothelial cells (BAEC). METHODS: Morphologic changes and quantification of apoptotic cells were determined under fluorescence microscope after a 24-h treatment of BAEC by H2O2. Cell viability was determined with MTT method. DNA fragmentation was visualized by agarose gel electrophoresis. The expression of phospho-p38 and phospho-p42/p44 CCDPK was measured by Western blotting. RESULTS: H2O2 elicited typical apoptotic morphologic changes (chromatic condensation, nucleus fragmentation) and DNA fragmentation. At 100-500 mumol.L-1, incubation of BAEC with H2O2 for 24 h also induced phospho-p38 and phospho-p42/p44 CCDPK expression in a concentration-dependent manner. Interestingly, H2O2-induced apoptosis was markedly increased by preincubation with U0126, a specific p42/p44 CCDPK inhibitor. However, SB203580, a specific p38 CCDPK inhibitor, enhanced the expression of phospho-p42/p44 CCDPK induced by H2O2, but had no effect on BAEC survival. CONCLUSION: p42/p44 CCDPK signaling appears to play protective roles in H2O2-induced apoptosis in BAEC, whereas p38 CCDPK is not the main signaling pathway mediating H2O2-induced cellular apoptosis.

Animals↗
PubMed2000

[Spatial variability of soil nutrients based on geostatistics combined with GIS--a case study in Zunghua City of Hebei Province].

Geostatistics combined with GIS was applied to analyze the spatial variability of soil nutrients in topsoil (0-20 cm) in Zunghua City of Hebei Province. GIS can integrate attribute data with geographical data of system variables, which makes the application of geostatistics technique for large spatial scale more convenient. Soil nutrient data in this study included available N (alkaline hydrolyzing nitrogen), total N, available K, available P and organic matter. The results showed that the semivariograms of soil nutrients were best described by spherical model, except for that of available K, which was best fitted by complex structure of exponential model and linear with sill model. The spatial variability of available K was mainly produced by structural factor, while that of available N, total N, available P and organic matter was primarily caused by random factor. However, their spatial heterogeneity degree was different: the degree of total N and organic matter was higher, and that of available P and available N was lower. The results also indicated that the spatial correlation of the five tested soil nutrients at this large scale was moderately dependent. The ranges of available N and available P were almost same, which were 5 km and 5.5 km, respectively. The range of total N was up to 18 km, and that of organic matter was 8.5 km. For available K, the spatial variability scale primarily expressed exponential model between 0-3.5 km, but linear with sill model between 3.5-25.5 km. In addition, five soil nutrients exhibited different isotropic ranges. Available N and available P were isotropic through the whole research range (0-28 km). The isotropic range of available K was 0-8 km, and that of total N and organic matter was 0-10 km.

China↗
PubMed2000

Effect of 8-bromo-cyclic AMP on neuron specific enolase, heat shock protein, nitric oxide, nitric oxide synthase and nitric oxide synthase mRNA in human retinoblastoma HXO-Rb44 cells and cell differentiation.

OBJECTIVE: To study the effect of 8-bromo-cyclic AMP (8-Br-cAMP) on nitric oxide synthase (NOS) mRNA, NOS and nitric oxide (NO) product, heat shock protein (hsp) 70 and neuron specific enolase (NSE) in human retinoblastoma HXO-Rb44 cells and the effect related to cell differentiation. METHODS: Cultured human retinoblastoma HXO-Rb44 cells were divided into two aliquots. One was cultured with 2 x 10(-5) mol/L of 8-Br-cAMP for 24 hours as the experiment group; the other was treated with no 8-Br-cAMP as the control group. The cell suspensions in concentration of 1 x 10(7)/ml in both groups were dropped onto the nitrocellulose membrane (NCM). The NOS mRNA was detected with the biotin-labeled NOS cDNA probe by RNA dot blot. The NOS activity was detected by protein dot blot. The immunoreactivity (IR) of hsp70 and NSE was detected by protein dot blot. The NO was detected by nitrate reductase method. NCM specimens were analyzed by a TLC scanner for detection of the dot blot signal intensity. RESULTS: The signals of NOS mRNA, NOS activity, hsp70-IR, NSE-IR, and NO content in the experiment group were higher than those in the control group (P < 0.05-0.01). CONCLUSIONS: 8-Br-cAMP could increase NO product and the expression of NOS mRNA, NOS, NSE and hsp70. The results indicate that 8-Br-cAMP could facilitate synthesis of NO in the neuroblastoma HXO-Rb44 cells, which could have tendency toward neuron development, suggesting that the increased hsp70, NO and NOS may involve cell differentiation of the retinoblastoma HXO-Rb44.

8-Bromo Cyclic Adenosine Monophosphate↗