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Biomedical subjects

Q Zhou

Publications and source records attributed to Q Zhou.

At least 289 records · Page 16Linked to original sources
PubMed1996

Two-dimensional crystallization of rabbit C-reactive protein on lipid monolayers.

Two-dimensional (2D) crystals of rabbit C-reactive protein (CRP) have been obtained by protein binding on lipid monolayers at the air/water interface. Two different types of crystalline arrays of CRP were obtained, by specific binding and non-specific adsorption to the lipids. Electron crystallographic analysis of the negatively stained specimens showed that the unit cell parameters of the CRP 2D crystals formed by specific binding were a=81 angstroms, b=78 angstroms, gamma=118.35 degrees, and those formed by nonspecific adsorption were a=74 angstroms, b=67 angstroms, gamma=95.5 degrees, both with the layer group p1. Projection maps were obtained at a resolution of 26 angstroms and 22 angstroms respectively. They showed that only the monomers of the CRP were packed in the 2D arrays and the orientations of the monomers on the lipid monolayers were different in the two types of crystals. By comparing the two projection maps, a preliminary shape of the CRP monomer has been derived. A model of the pentameric structure of the oligomeric CRP has been proposed.

Adsorption↗
PubMed1996

p53 protein accumulation and gene mutations in multifocal esophageal precancerous lesions from symptom free subjects in a high incidence area for esophageal carcinoma in Henan, China.

BACKGROUND: Multifocal occurrence of precancerous lesions of the esophagus has been observed among individuals in a high incidence area for esophageal carcinoma in Henan Province, China. Results from recent studies suggest that p53 protein accumulation and mutation occur early in the pathogenesis of esophageal carcinoma. Discordant p53 gene mutations have been observed in invasive carcinoma and preinvasive lesions from a patient with esophageal carcinoma. The p53 alterations in the multifocal precancerous lesions from symptom-free subjects, however, have not been investigated. METHOD: Two biopsy samples, one each from the middle-third and the lower-third of the esophagus, from each subject, were taken from 55 symptom-free subjects in a high incidence area for esophageal cancer in Huixian, Henan Province, China. p53 protein accumulation and p53 gene mutation were analyzed in the multifocal esophageal precancerous lesions from these subjects. RESULTS: Histopathologic examination showed that among the 110 biopsies, 20 had dysplasia, 72 had basal cell hyperplasia, and 18 had normal epithelia. Concurrent lesions at the middle- and lower-third biopsy occurred in 2 subjects with dysplasia (2 of 55 subjects, 4%) and 26 subjects with basal cell hyperplasia (26 of 55 subjects, 47%). Analysis by immunohistochemistry showed high concurrent rates of p53 protein accumulation (51 of 55 subjects, 93%). p53 sequence analysis of 32 samples from 16 subjects identified missense mutations in 5. In one subject, there were three different mutations in the middle-third biopsy (codon 161, GCC-->GAC) and the lower-third biopsy (codon 159, GCC-->CCC). A single mutation was detected in the other four subjects in either the middle- or lower-third biopsy. CONCLUSIONS: The present findings indicate that p53 protein accumulation and mutations occur in the early stages of human esophageal carcinogenesis. Independent somatic mutations of the p53 tumor suppressor gene and protein accumulation in different regions of the esophageal "field" might be key molecular events in multifocal esophageal carcinogenesis.

Adult↗
PubMed1996

The hemorrhagin catrocollastatin inhibits collagen-induced platelet aggregation by binding to collagen via its disintegrin-like domain.

Catrocollastatin, a 50 kDa snake venom protein purified from Crotalus atrox, specifically inhibits platelet-collagen adhesion and collagen-induced aggregation. Catrocollastatin is composed of an N-terminal domain, a metalloproteinase domain, a disintegrin-like domain and a cysteine-rich C-terminal domain. The present studies show that catrocollastatin exerts its effect by binding to collagen. Based on the amino acid sequence and homology analysis, a cyclic oligopeptide corresponding to a conservative fragment containing the sequence SECD in the disintegrin-like domain has been synthesized. Like its protein parent, the synthetic peptide inhibits collagen-induced aggregation and possesses the ability to bind to collagen. This is the first snake venom protein with a disintegrin-like structure shown to bind to an integrin ligand matrix molecule instead of an integrin.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1996

Cholestane-3 beta, 5 alpha, 6 beta-triol stimulates phospholipid synthesis and CTP-phosphocholine cytidyltransferase in cultured LLC-PK cells.

The present study was conducted to examine the effect, if any, of triol on the rate of total or individual phospholipid synthesis by LLC-PK cells in culture. LLC-PK cells were incubated in medium with or without 10 micrograms/ml of 5 alpha-cholestane-3 beta, 5 alpha,6 beta-triol (triol) for 24 h. Triol-treated and control cells were then incubated with medium containing either [14C]glycerol or [32P]phosphate for 1, 6 or 12 hr. In triol-treated cells, the amount of labeled glycerol and [32P]phosphate incorporated into glycerophospholipids and phospholipids (PL), respectively, were higher in triol-treated cells than in control cells, indicating a higher rate of PL synthesis in triol-treated cells. The results also showed that the increase in PL synthesis was higher in magnitude for some PL than others, thus disturbing the ratios among the PL fractions in the cell membrane. CTP-phosphocholine cytidyltransferase activity was greatly enhanced in the cytosolic as well as the particulate fractions of the triol-treated cells, which explains the increase of PC synthesis under triol effect. The rate of [3H]acetate incorporation into the total and free fatty acid fractions was significantly increased in triol-treated cells. The activation of the cytidyl transferase enzyme was related to the enhanced de novo synthesis and cellular uptake of fatty acids in triol-treated cells, which make fatty acids more available in these cells and can upregulate the enzyme. The increased synthesis of phospholipids in the triol cells and the increased level of phospholipid in these cells (as micrograms lipid phosphorus/mg cell protein) observed in our previous study indicate changes in the phospholipid head group composition of the triol cells. These changes can affect several membrane properties and membrane bound enzymes.

Acetates↗
PubMed1996

Expression of recombinant CD59 with an N-terminal peptide epitope facilitates analysis of residues contributing to its complement-inhibitory function.

CD59 is a plasma membrane-anchored glycoprotein that serves to protect human cells from lysis by the C5b-9 complex of complement. The immunodominant epitopes of CD59 are known to be sensitive to disruption of native tertiary structure, complicating immunological measurement of expressed mutant constructs for structure function analysis. In order to quantify cell-surface expression of wild-type and mutant forms of this complement inhibitor, independent of CD59 antigen, an 11-residue peptide (TAG) recognized by monoclonal antibody (mAb) 9E10 was inserted before the N-terminal codon (L1) of mature CD59, in a pcDNA3 expression plasmid. SV-T2 cells were transfected with this plasmid, yielding cell lines expressing 0 to > 10(5) CD59/cell. The TAG-CD59 fusion protein was confirmed to be GPI-anchored, N-glycosylated and showed identical complement-inhibitory function to wild-type CD59, lacking the TAG peptide sequence. Using this construct, the contribution of each of four surface-localized aromatic residues (4Y, 47F, 61Y, and 62Y) to CD59's complement-inhibitory function was examined. These assays revealed normal surface expression with complete loss of complement-inhibitory function in the 4Y --> S, 47F --> G and 61Y --> S mutants. By contrast, 62Y --> S mutants retained approximately 40% of function of wild-type CD59. These studies confirmed the utility of the TAG-CD59 construct for quantifying CD59 surface expression and activity, and implicate surface aromatic residues 4Y, 47F, 61Y and 62Y as essential to maintenance of CD59's normal complement-regulatory function.

Antibodies, Monoclonal↗
PubMed1996

Inhibiting effects of spermidine derivatives on Trypanosoma cruzi trypanothione reductase.

Trypanothione reductase is a vital component of the antioxidant defenses of trypanosomes. This enzyme reduces trypanothione, a spermidine-glutathione conjugate. The inhibitory effects of several spermidine derivatives on the reduction of trypanothione by Trypanosoma cruzi trypanothione reductase were assessed. Spermidine derivatives containing hydrophobic aromatic substituents were found to be competitive inhibitors of trypanothione reductase. N4-acylated spermidine derivatives were less effective inhibitors than the corresponding N4-alkylated derivatives. The most effective compounds studied were N1, N8-bis(2-naphthylmethyl)spermidine and N4-(2-naphthylmethyl)spermidine, with Ki values of 9.5 and 108 microM, respectively.

Animals↗
PubMed1996

Molecular biomarkers of occupational lung cancer.

Occupational exposures to certain metals, hydrocarbons and ionizing radiation are associated with increased lung cancer in workers; because these exposures continue, lung cancer remains an important problem in industrialized nations. The gravity of the lung cancer, specifically the low cure rate associated with the disease, has forced researchers to focus efforts at developing biological indicators (biomarkers) of carcinogen exposure and early, reversible effects. This review examines critically the development of these biomarkers for occupational and environmental exposures to polycyclic aromatic hydrocarbons (PAH), a ubiquitous class of lung carcinogens. Biomarkers of several different stages of the carcinogenic process have been proposed. Industrial hygiene and occupational health emphasize exposure and disease prevention. For this reason, biomarkers useful in industrial hygiene practice are those which measure events prior to the initiation phase of carcinogenesis; markers of later events which have a greater positive predictive value may measure irreversible effects and are more appropriate for disease screening and epidemiology. One of the strengths of biological monitoring is that exposures and effects can be measured regardless of route. Data indicates that the dermal route may be a significant pathway for delivery of PAH to the lung. This finding has important ramifications because as airborne exposure limits decrease the relative impact of dermal absorption is increased.

Carcinogens↗
PubMed1996

Inhibition by aminoguanidine of glucose-derived collagen cross-linking in skeletal muscle of broiler breeder hens.

Aminoguanidine (AG) is a nucleophilic compound that inhibits nonenzymatic, glucose-derived collagen cross-linking in animal tissues. Whether AG can attenuate the accumulation of collagen cross-links in the Biceps femoris muscle of 64-wk-old broiler breeder hens as well as improve meat quality, was investigated. Eighty-four broiler breeder hens (30-wk-old) were divided into four equal groups. Each group was assigned randomly to diets supplemented with 0. 200, 400, or 800 ppm AG, respectively. Birds were fed individually, 150 g diet/d. After feeding AG for 34 wk, six birds from each group were killed and samples from the leg muscle were analyzed for changes in collagen content. Aminoguanidine decreased (P < 0.05) glucose-derived collagen cross-links in skeletal muscle as measured by fluorescence and collagen solubility. Insoluble collagen fraction decreased with increasing AG dosage, whereas acid-soluble and pepsin-soluble fractions increased with increasing AG dosage. Aminoguanidine did not affect shear force. In agreement with studies on animals with diabetes, AG is a potent inhibitor of glucose-derived cross-linking in chickens although the results from the measurements of shear force do not support its used for improving carcass quality in spent hens.

Animals↗
PubMed1996

The Short Inflammatory Bowel Disease Questionnaire: a quality of life instrument for community physicians managing inflammatory bowel disease. CCRPT Investigators. Canadian Crohn's Relapse Prevention Trial.

OBJECTIVE: Health-related quality of life (HRQOL) affects outcome in chronic diseases such as inflammatory bowel disease (IBD). The inflammatory bowel disease questionnaire (IBDQ), a disease-specific HRQOL questionnaire, can define changes in health status in IBD, but simple instruments are needed for daily application. The present study proposed to develop a short version of the IBDQ, the SIBDQ, for community physicians. METHODS: Using data from a clinical trial in 149 patients with Crohn's disease, 10 items were selected (by forward stepwise regression) that best explained the variance of the IBDQ or dimensional scores (bowel, systemic, social, emotional). The validity, reliability, and responsiveness of the SIBDQ were then assessed in 150 different patients with Crohn's disease and 45 with ulcerative colitis. All scores were reported with a 7-point scale (1 = poor HRQOL, 7 = optimum HRQOL). RESULTS: Mean SIBDQ scores were similar (p = 0.22) in Crohn's patients among 14 participating centers at study entry. Mean scores were lower in active Crohn's disease (range 4.00-4.92) than inactive disease (range 4.67-5.83; p = 0.0015). In active ulcerative colitis, the mean SIBDQ was 4.79 +/- 1.17 compared to 5.90 +/- 0.80 (p = 0.0006) in inactive disease. The SIBDQ explained 92% and 90% of the IBDQ variance in Crohn's disease and ulcerative colitis, respectively. In patients with stable Crohn's disease, the test-retest reliability coefficient was 0.65 and Crohnbach's alpha was 0.78, indicating good reliability. In patients with Crohn's disease who relapsed during follow-up, the mean SIBDQ decreased by -0.93 + 0.55 (p = 0.001). CONCLUSION: The SIBDQ is valid, reliable, and able to detect meaningful clinical changes in HRQOL that might occur in the office setting.

Adult↗
PubMed1996

Pharmacologic characteristics of potentiation of 5-HT3 receptors by alcohols and diethyl ether in NCB-20 neuroblastoma cells.

We have examined the actions of alkanols, halogenated ethanol derivatives and diethyl ether on ion current mediated by 5-HT3 receptors in NCB-20 neuroblastoma cells. The alcohols and diethyl ether potentiated 5-HT3 receptor-mediated ion current at concentrations that had no effect on membrane current when applied in the absence of agonist. The potency of alcohols increased with increasing hydrophobicity. However, the maximal efficacy of alcohols was unrelated to hydrophobicity. Interactions between different drugs applied simultaneously to cells were examined to determine whether these compounds compete for a distinct modulatory site associated with the 5-HT3 receptor. Analysis of interactions observed at different drug concentrations indicated a variety of interactions between different compounds, ranging from negative to positive allosteric interactions. Interactions between trichloroethanol (TCEt) and isopentanol exhibited characteristics that might indicate competition for a single site of action. However, further examination of interactions between these two drugs indicated that although isopentanol altered the efficacy of co-applied TCEt, TCEt did not have a similar effect with respect to isopentanol. Furthermore, isopentanol did not alter the potency of TCEt for potentiation of receptor function. The absence of competitive interactions among alcohols indicates that a single "alcohol receptor" cannot be defined using established pharmacologic approaches. Our findings are most consistent with the idea that alcohols interact with several hydrophobic sites associated with the 5-HT3 receptor.

Animals↗
PubMed1996

Reproducibility of an esophageal biopsy sampling procedure in a high-incidence area for esophageal cancer in northern China.

The objective of this study was to evaluate the reproducibility of the biopsy sampling procedure in research on esophageal lesions. Biopsies were taken from the middle and lower thirds of the esophagus, one from each site, from 25 subjects in a high-incidence area for esophageal cancer in Xinye County of Henan Province, China. The biopsy sampling procedure was repeated on the same subjects 10 days later. When the biopsies were analyzed together and those with worse pathologies were used for diagnosis, 52% of the subjects had the same grade of lesions in the second biopsy examination, 32% had lower-grade lesions, and 16% had higher-grade lesions.

Adult↗
PubMed1996

Cholesterol metabolism in human umbilical arterial endothelial cells cultured in low magnesium media.

To study the time- and dose-dependent effects of low magnesium on free [H3]cholesterol uptake, [H3]mevalonolactone incorporation into cholesterol, and both of which labelled precursors and [H3]oleic acid incorporations into cholesteryl esters, cultured human umbilical arterial endothelial cells were exposed to experimental media containing decreasing magnesium concentrations at 94, 188, 376 and 564 microM until 48 h. A level of magnesium at 949 microM was used as a control. The results showed that reduced magnesium in the cultured medium led to a decrease in [H3]cholesterol, uptake, an inhibition of the incorporation of [H3]mevalonolactone into cholesterol and a stimulation of the incorporation of [H3]cholesterol, [H3]mevalonolactone and [H3]oleic acid into cholesteryl esters, but the time- and dose-dependent effects of magnesium deficiency were not significant. We suggest that reduced cholesterol uptake and synthesis might contribute to hypercholesterolaemia under a condition of magnesium deficiency, and that enhanced cholesterol esterification might be explained by a stimulated activity of acyl-Coenzyme A: cholesterol O-acyltransferase (ACAT).

Cells, Cultured↗
PubMed1996

[The clinical value of fetal congenital heart disease diagnosed by color Doppler echocardiography].

OBJECTIVE: To investigate the clinical value of color Doppler echocardiography for the diagnosis of fetal congenital heart disease (CHD). METHODS: 368 cases of high risk fetuses of CHD, aged from 20-40 gestational weeks, were examined by color Doppler echocardiography with Acuson 128 x P/10 color Doppler flow imaging system. The prenatal echocardiographic diagnosis were confirmed by fetal autopsy and echocardiographic examine after birth as well as follow-up. RESULTS: 11 cases of fetal CHD were detected by prenatal echocardiography, of those, 5 cases of CHD were confirmed by fetal autopsy after induction of labor and 5 cases of CHD were confirmed by color Doppler echocardiography after birth, 1 case of false-positive and 1 case of false-negative. CONCLUSIONS: The study suggests that four-chamber view is an important view for detecting fetal CHD by echocardiography, but multiple views are necessary for diagnosis of fetal complex CHD. Color Doppler echocardiography lists as the first choice for prenatal diagnosis of fetal CHD.

Adult↗
PubMed1996

[Acupuncture and cortical evoked potentials].

Research works for the effects of acupuncture on cortical evoked potentials were reviewed since 1970 in this article. As a result of the acupuncture anesthesia being applied widely in clinical operation, most of the studies were focused on the evoked potential of somatosensory cortex for elucidating the principle of the analgesic effect of acupuncture, while less observations were reported on the aspects of auditory and visual cortex. The amplitude of the evoked potential was often used as an index in assessing the excitability of the cerebral cortex in the studies of the effect of acupuncture in the past. An increase in the amplitude of evoked potential means an excitory process of the cortex and a decrease means depression. Based on their work, the authors consider that whether the change in the amplitude of cortical evoked potential could be served as an optional index in reflecting the excitability of the cortex is still a problem in neurophysiology remained for further investigation.

Acupuncture Therapy↗
PubMed1996

[Observation on TXB2 and 6-keto-PGF1 alpha in serum of patients with cor pulmonale].

To know the changes of TXA2 and PGI2 in serum of patients with cor pulmonale, the levels of their stable metabolites TXB2 and 6-keto-PGF1 alpha in serum were examined in 28 patients with cor pulmonale during alleviation, 29 patients with cor pulmonale during exacerbation before and after treatment and 10 healthy subjects. TXB2 and 6-keto-PGF1 alpha were 109.74 +/- 56.14 ng/L and 54.76 +/- 35.62 ng/L respectively in healthy subjects; TXB2/6-keto-PGF1 alpha = 2.004. The TXB2 level of patients with cor pulmonale at every stage was higher than that of healthy subjects (P < 0.05-0.01). Patients with cor pulmonale during exacerbation had the highest TXB2 level of 709.22 +/- 354.49 ng/L, which decreased to 408.24 +/- 289.41 ng/L (P < 0.05) after treatment with traditional Chinese medicine combined with western medicine and the decreased level as such was not significantly different from that during alleviation (333.14 +/- 324.14 ng/L). The 6-keto-PGF1 alpha level in patients with cor pulmonale at every stage was not significantly different from that of healthy subjects. Since TXB2 increased, the value TXB2/6-keto-PGF1 alpha of patients with cor pulmonale was greater than that of healthy subjects. It is most likely that chronic hypoxia and hypercapnia lead to prostaglandin release in the lung of patients with cor pulmonale; hypoxia and hypercapnia become more severe during exacerbation resulting from infection; which lead to increased prostaglandin release, then high TXB2 level ensue as the result. TXB2 decreases after amelioration of hypoxia during treatment. But the change of 6-keto-PGF1 alpha is not obvious.

6-Ketoprostaglandin F1 alpha↗
PubMed1996

[Clinical application of spleno-renal shunt].

The results of splenorenal shunt (SRS) in 405 patients were compared with those of simple splenectomy (SS) in 376 cirrhotic patients in the treatment of portal hypertension. The recurrent bleeding rate was 10.12% in SRS group and 21.2% in SS group, respectively (P < 0.001). The mortality of rebleeding was 2.96% in SRS group and 10.6% in SS group, respectively (P < 0.01). Death from hepatic failure developed at 16.5% of SRS patients and at 9.8% of SS patients, respectively (P < 0.01). The rate of postoperative variceal bleeding and mortality in prophylactic SRS group were 4.9% and 6.2%, and 15.1% and 26.4% in prophylactic SS group, respectively (P < 0.01). The authors are in favor of prophylactic SRS and modified side-to-side SRS for its simplicity and good results.

Adult↗