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Biomedical subjects

L Zhao

Publications and source records attributed to L Zhao.

479 records · Page 27Linked to original sources
PubMedDate not supplied

Dynamic change of ERPs related to selective attention to signals from left and right visual field during head-down tilt.

To study further the effect of head-down tilt (HDT) on slow positive potential in the event-related potentials (ERPs), the temporal and spatial features of visual ERPs changes during 2 hour HDT (-10 degrees) were compared with that during HUT (+20 degrees) in 15 normal subjects. The stimuli were consisted of two color LED flashes appeared randomly in left or right visual field (LVF or RVF) with same probability. The subjects were asked to make switch response to target signals (T) differentially: switching to left for T in LVF and to right for T in RVF, ignoring non-target signals(N). Five sets of tests were made during HUT and HDT. ERPs were obtained from 9 locations on scalp. The mean value of the ERPs in the period from 0.32-0.55 s was taken as the amplitude of slow positive potential(P400). The main results were as follows. 1) The mean amplitude of P400 decreased during HDT which was more significant at the 2nd, 3rd and 5th set of tests; 2) spatially, the reduction of mean P400 amplitude during HDT was more significant for signals from RVF and was more significant at posterior and central brain regions than that on frontal locations. As that the positive potential probably reflects the active inhibition activity in the brain during attention process, these data provide further evidence showing that the higher brain function was affected by the simulated weightlessness and that this effect was not only transient but also with interesting spatial characteristics.

Adult↗
PubMedDate not supplied

Expression and characterization of bryodin 1 and a bryodin 1-based single-chain immunotoxin from tobacco cell culture.

Bryodin 1 (BD1) is a potent ribosome-inactivating protein (RIP) isolated from the plant Bryonia dioica. It is relatively nontoxic in rodents (LD50 > 40 mg/kg) and represents a potential improvement over other RIPs and bacterial toxins that have been used in immunotoxins. Recombinant BD1, expressed in Escherichia coli, localizes to insoluble inclusion bodies necessitating denaturation and refolding steps to generate active protein. In this report, BD1 was expressed as a soluble recombinant protein in tobacco cell culture (ntBD1) and purified to near homogeneity with yields of up to 30 mg/(L of culture). The protein synthesis inhibition activity of ntBD1 was identical to that of both native BD1 isolated from the roots of B. dioica and recombinant BD1 expressed in E. coli. Toxicology analysis showed that ntBD1 was well tolerated in rats at doses that cannot be achieved with most other toxin components of immunotoxins. Additionally, a single-chain immunotoxin composed of BD1 fused to the single-chain Fv region of the anti-CD40 antibody G28-5 (ntBD1-G28-5 sFv) was expressed in tobacco tissue culture as a soluble protein and was specifically cytotoxic toward CD40 expressing non-Hodgkin's lymphoma cells in vitro. These data indicate that tobacco tissue culture is a viable system for soluble expression of BD1 and BD1-containing immunotoxins.

Animals↗
PubMedDate not supplied

Lateral placental growth occurs by trophoblast cell invasion of decidual veins.

During human pregnancy, growth of the placenta is proportionally greater than the growth of the decidual surface, suggesting that trophoblast cells invade the decidua at the placenta's margin. We hypothesized that a method of lateral placental growth was trophoblast cell invasion of decidual veins. This was investigated in two in situ pregnancies and in tissues from 100 women undergoing elective termination at 8-12 weeks of gestation. Decidua was compared to normal secretory endometrium. Histological sections were stained by immunohistochemistry to identify trophoblast cell and vascular antigens, as well as vascular cell adhesion molecule (VCAM), integrin subunits beta(1)and beta(4), and oncofetal fibronectin. Dilated veins were observed in all decidua but not in the secretory endometrium. Decidual and myometrial veins contained villi, trophoblast cell islands and syncytial elements. Decidual endothelial cells expressed vascular cell adhesion molecule (VCAM). Villous trophoblast cells were integrin subunits beta(4)positive and beta(1)negative. Trophoblast cell islands in the placenta and within decidual veins were integrin subunits beta(1)positive and beta(4)negative. Trophoblast cell islands and villi attached to veins, and mononuclear cells, invaded decidual stroma. Oncofetal fibronectin was present at sites of trophoblast invasion. These findings suggest that a method of lateral placental growth is trophoblast cell invasion of veins.

Cell Movement↗
PubMedDate not supplied

Uptake of chloroform by skin on brief exposures to the neat liquid.

The uptake of chloroform into hairless rat's stratum corneum after application of the neat solvent directly to the skin has been studied. Tape stripping was used to determine amounts deposited within the stratum corneum and also the clearance of the compound from the skin following varied levels of exposure. Three minutes exposure to neat chloroform was adequate to achieve a limiting accumulation in the stratum corneum and thus it appears to take this long for the gradient of chloroform to be established fully across this structure. There was indication of progressively deeper penetration of chloroform as the exposure time was increased from 1 to 8 minutes. Local irritation and a loosening of the superficial layers of stratum corneum were apparent with as little as 2 minutes of exposure to the solvent and were exacerbated with further increases in exposure duration. Following exposure, clearance of the solvent from the skin surface was rapid. Interestingly, the rate of clearance, as followed by stripping, was comparable on live and freshly euthanized rats. This implies that once the exposure is terminated evaporation from the surface, and not systemic uptake by way of the local vasculature, is the predominant means of clearance at an open surface.

Analysis of Variance↗
PubMedDate not supplied

Systemic uptake and clearance of chloroform by hairless rats following dermal exposure: II. Absorption of the neat solvent.

Blood concentrations of chloroform were monitored after exposing small areas (approximately 5.5 cm2) of the backs of hairless rats to liberal excesses of the solvent for either 1, 3, or 8 min. The amounts absorbed were quantified by comparing areas-under-the-curves (AUCs) of blood concentration versus time plots to the AUC obtained on infusing an aqueous chloroform solution of known concentration for 30 min (positive control). Chloroform penetrated the dermal barrier rapidly, the skin's horny layer and the deeper skin tissues acting as reservoirs for chloroform only for short durations. Evaporative and physiological clearance from these reservoirs was rapid once the chloroform was removed from the surface. Pressure of the template used to confine the exposure affected uptake. For blood levels, the time to reach the maximum blood concentration increased with increased exposure duration. Amounts absorbed also depended on exposure duration. Blood level profiles indicated systemic uptake of chloroform following a 3-min exposure was about 1.3-fold higher than for a 1-min exposure (not significant), while the 8-min exposure produced an AUC roughly 3.8-fold higher than found at 3 min (p = 0.026). Chloroform is rapidly cleared from rat blood (terminal elimination rate constant = 0.009/min). Calculations indicated that its absorption from these area-limited exposures far exceeds that which would be absorbed had the chloroform been presented to the skin as a saturated aqueous solution.

Administration, Cutaneous↗
PubMedDate not supplied

Methylation status of the fragile histidine triad and E-cadherin genes in plasma of cervical cancer patients.

Recent evidence suggests that tumor cells may release DNA into the serum and plasma of afflicted cancer patients. However, no report existed regarding the methylation status of the fragile histidine triad (FHIT) and E-cadherin genes in plasma samples of cervical cancer patients. Methylation-specific PCR (MSP) was employed to examine CpG island methylation of the FHIT and E-cadherin genes in 151 pretreatment plasma samples and 30 tumor tissue samples from cervical cancer patients. MSP products were cloned and sequenced. CpG island methylation of the FHIT and E-cadherin genes was detected in 30.46% and 39.74% of plasma samples, respectively, and in 53.33% and 60.0% of tissue samples, respectively. The total concordance rate of methylation between plasma samples and tissue samples in FHIT gene was 80.00% and that in E-cadherin gene was 76.66%. At least one of the two methylated genes was detected in 56.29% of plasma samples and 76.7% of tissue samples. The presence of both methylated genes was detected in 13.9% of plasma samples and 36.67% of tissue samples. We found that the higher the clinical stage and histologic grade, the higher the rate of methylation in both genes in plasma samples. CpG island methylation of the FHIT and E-cadherin genes is present in plasma of cervical cancer patients. Using the two genes as markers simultaneously may allow clinicians to diagnose and evaluate the effect of treatment earlier and using fewer invasive procedures.

Acid Anhydride Hydrolases↗
PubMedDate not supplied

Evaluation of the European Spondyloarthropathy Study Group (ESSG) classification criteria in a Chinese population.

OBJECTIVE: To evaluate for thefirst time in a Chinese population, the usefulness of the European Spondyloarthropathy Study Group (ESSG) criteria. METHODS: A total of 193 clinically diagnosed SpA patients were compared to 166 patients with other types of arthritis, using the parameters listed in the ESSG criteria. RESULTS: The sensitivity and specificity of the ESSG criteria in this Chinese population were high at 85.4% and 96.4% respectively. CONCLUSION: The use of ESSG criteria for classifying SpA in Chinese will not lead to significant omission of SpA patients or inclusion of patients who do not have SpA.

China↗
PubMedDate not supplied

Serum pepsinogens in relation to precancerous gastric lesions in a population at high risk for gastric cancer.

Concentrations of serum pepsinogens (PG) I and II were determined for 3252 randomly selected adults who participated in a population-based gastroscopic screening in an area of China with one of the world's highest rates of gastric cancer. PG I and II concentrations in both sexes tended to be higher than reported in other countries, with levels generally higher among males than females. PG I tended to decrease and PG II to increase with age, but the most pronounced associations were between PG I:II ratios and gastric histology. Median PG I:II ratios monotonically declined from 9.1 to 7.2 to 5.7 to 5.4 to 3.8 among those with superficial gastritis, chronic atrophic gastritis, intestinal metaplasia, dysplasia, and stomach cancer, respectively. The prevalence of dysplasia was nearly 3 times greater among those with PG I:II ratios less than 3 compared with those whose PG I:II ratios were greater than 10. While average levels differed significantly among the histologic groups, the PG I:II ratios were neither sensitive nor specific markers of an individual's likelihood of advanced gastric lesions in this population.

Adult↗
PubMedDate not supplied

Gas chromatographic determination of chlorothalonil in leaves and roots of Scrophularia and in soil.

A gas chromatographic method is described for determination of chlorothalonil residues in leaves and roots of Scrophularia and in soil. Samples were extracted with acetone and cleaned up on a Florisil column. Chlorothalonil residues are chromatographed directly on a glass column of 1.5% OV-17 and 2% QF-1 coated on 80-100 mesh Chromosorb W (HP) support and measured with a 63Ni electron capture detector. Detection limits are 0.001 ppm for leaf, 0.005 ppm for root, and 0.001 ppm for soil.

Chromatography, Gas↗
PubMedDate not supplied

Interphase fluorescence in situ hybridization analysis: a study using centromeric probes 7, 8, and 12.

Interphase fluorescence in situ hybridization (I-FISH) is a useful technique for detecting chromosomal numerical abnormalities in tumors and is gaining acceptance as a tool in cytogenetics and clinical diagnoses. Performance and quality control information about commercial products are necessary in order to implement an individual FISH probe as a routine clinical laboratory test. Interphase FISH analysis was performed with three commercially available alpha-satellite chromosome-specific DNA centromeric probes (D7Z1/D7Z2; D8Z2; and D12Z3) on bone marrow material prepared for conventional cytogenetic analysis. The results were interpreted following enumeration of the signals in 500 interphase nuclei each by two different observers. A mean of 93.92 percent (+/- 1.3 percent, 1 SD) was found for chromosome 7; a mean of 93.91 percent (+/- 1.5 percent, 1 SD) was found for chromosome 8, and a mean of 92.85 percent (+/- 1.4 percent, 1 SD) was found for chromosome 12. The results of the study demonstrated that I-FISH using chromosome centromeric probe(s) is a reliable, reproducible, and accurate technique. This technique can be integrated into routine clinical practice with proper quality control protocols.

Bone Marrow↗