Biomedical subjects

X Zhou

Publications and source records attributed to X Zhou.

At least 649 records · Page 36Linked to original sources

PubMed1995

Characterization of TAP-independent and brefeldin A-resistant presentation of Sendai virus antigen to CD8+ cytotoxic T lymphocytes.

H-2Kb-transfected T2 cells, which lack both TAP1/2 and LMP2/7 genes, are able to efficiently process and present Sendai virus Antigen to Kb-restricted Sendai virus-specific CTL. This presentation is not inhibited by Brefeldin A (BFA). Here we extend our analysis of this novel antigen presentation pathway. We show that presentation of Sendai virus antigen was not due to sensitization of T2Kb cells by peptides in the virus preparation or peptides released from virus infected cells. Also, the ability to present Sendai virus in a BFA resistant fashion was specific for cells of the T2 lineage. Re-expression of TAP1/2 genes in T2Kb cells did not alter the capability to present antigen in a BFA resistant fashion, i.e. the presence of a functional TAP transporter complex did not relocate (all) peptides to the classical pathway for antigen processing and presentation. We found that co-infection of T2Kb cells with either Sendai virus plus influenza virus or Sendai virus plus VSV did not relocate presentation of influenza or VSV antigen to the TAP independent BFA resistant antigen presentation pathway. Peptide elution experiments and studies with peptide-specific CTL firmly demonstrated that the antigen presented by T2Kb cells after infection with Sendai virus was the natural Sendai virus epitope NP324-332. The same epitope, when expressed as a minigene in vaccinia virus, could be presented also by T2Kb cells but this presentation could be blocked by BFA. Thus, the TAP independent BFA resistant presentation of antigen seem cell (T2 lineage) and virus (Sendai virus) specific, but not epitope specific. The ability of T2Kb cells to present Sendai virus antigen in a TAP independent BFA resistant fashion was only partially blocked by lysosomal inhibitors such as methylamine, ammonium chloride and chloroquine. These findings demonstrate that TAP1/2-independent and BFA-resistant class I processing is only expressed in certain cell types, in parallel with classical MHC class I processing, and that Sendai virus selectively can enter this pathway. Hypothetical models for the TAP-independent class I processing are discussed.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1995

Correlation among fibrillation, defibrillation, and cardiac pacing.

An electrical stimulus must create an electric field of approximately 1 V/cm in the extracellular space to stimulate myocardium during diastole. To initiate fibrillation by premature stimulation during the vulnerable period or to defibrillate, an extracellular electric field of approximately 6 V/cm is required, a value approximately six times greater than that necessary for diastolic pacing. Yet, the current strength of the pulse given to the stimulating electrode to initiate fibrillation or to defibrillate is much greater than six times the diastolic pacing threshold. The ventricular fibrillation threshold is typically 40 times greater than the diastolic pacing threshold expressed in terms of current. The defibrillation threshold in terms of current is typically thousands of times greater than the diastolic pacing threshold. The reason that these thresholds vary so much more in terms of stimulus current than in terms of extracellular potential gradient is that each of the three thresholds requires creation of the required potential gradient at different distances from the stimulating electrode. Pacing requires a potential gradient of approximately 1 V/cm only in a small liminal volume of tissue immediately adjacent to the electrode. Initiation of ventricular fibrillation by premature stimulation during the vulnerable period requires a potential gradient of approximately 6 V/cm about 1 cm away from the stimulating electrode to allow sufficient space for the central common pathway of a figure-eight reentrant circuit to form. Since the potential gradient falls off rapidly with distance from the stimulating electrode, a stimulating current about 40 times greater than the diastolic pacing threshold is required to generate an electric field of 6 V/cm approximately 1 cm away from the stimulating electrode. Defibrillation requires an electric field of approximately 6 V/cm throughout all or almost all of the ventricular myocardium. Since some portions of the ventricles can be more than 10 cm away from the defibrillation electrodes, a shock of several amps is required to create this field, a current thousands of times greater than the pacing threshold.

Animals↗

PubMed1995

Responses of the transmembrane potential of myocardial cells during a shock.

INTRODUCTION: The purpose of this investigation was to study the transmembrane potential changes (delta Vm) during extracellular electrical field stimulation. METHODS AND RESULTS: Vm was recorded in seven guinea pig papillary muscles in a tissue bath by a double-barrel microelectrode with one barrel in and the other just outside a cell while shocks were given across the bath. The short distance (15 to 30 microns) between the two microelectrode tips and alignment of the tips parallel to the shock electrodes eliminated the shock artifact. Following ten S1 stimuli, an S2 shock field created by a 10-msec square wave was delivered during the action potential plateau or during diastole through shock electrodes 1 cm on either side of the tissue. Four shock strengths creating field strengths of 1.7 +/- 0.1, 2.9 +/- 0.2, 6.1 +/- 0.6, and 8.8 +/- 0.9 V/cm were given for the same impalement. Both shock polarities were given at each shock strength. For shocks delivered during the action potential plateau, the magnitudes of the peak delta Vm caused by the above four potential gradients were 21.1 +/- 8.2, 33.6 +/- 13.6, 49.9 +/- 24.2, and 52.3 +/- 28.0 mV (P < 0.05 among the four groups) for the shocks causing depolarization and 37.9 +/- 14.2, 56.6 +/- 16.4, 83.1 +/- 19.4, and 92.9 +/- 29.1 mV (P < 0.05 among the four groups) for the shocks causing hyperpolarization. Though delta Vm increased as potential gradients increased, the relationship was not linear. The magnitude of hyperpolarization was 1.9 +/- 0.5 times that of depolarization when the shock polarity was reversed (P < 0.05). As potential gradients increased from 1.7 +/- 0.1 to 8.8 +/- 0.9 V/cm, the time constant of the membrane response decreased significantly from 3.5 +/- 1.8 to 1.6 +/- 0.7 msec for depolarizing shocks and from 6.0 +/- 3.1 to 3.4 +/- 1.9 msec for hyperpolarizing shocks (P < 0.01 vs depolarizing shocks). For shocks delivered during diastole, hyperpolarizing shocks induced triphasic changes in Vm during the shock, i.e., initial hyperpolarization, than depolarization, followed again by hyperpolarization. CONCLUSION: During the action potential plateau, the membrane response cannot be represented by a classic passive RC membrane model. During diastole, activation upstrokes occur even during hyperpolarization caused by shocks creating potential gradients between approximately 2 and 9 V/cm.

Animals↗

PubMed1995

Optical transmembrane potential measurements during defibrillation-strength shocks in perfused rabbit hearts.

To study the optical transmembrane potential change (delta F) induced during shocks, optical recordings were obtained in 15 isolated perfused rabbit hearts treated with the potentiometric dye di-4-ANEPPS and diacetyl monoxime. Shock electrodes were sutured on the right and left ventricles. A laser beam 30 microns in diameter was used to optically excite di-4-ANEPPS. Fluorescence from a region 150 microns in diameter was recorded during a shock. In the macroscopic study (six animals), there were nine recording spots that were 3 mm apart between the two shock electrodes. In the microscopic study, there were three recording regions that were 3 mm away from either shock electrode and midway between them, with nine recording spots that were 30 microns (three animals), 100 microns (three animals), and 300 microns (three animals) apart in each region. After 20 S1 stimuli, a 10-ms truncated exponential S2 shock of defibrillation-threshold strength was given during the plateau of the last S1 action potential. In the microscopic study, shocks were also given during diastole, with delta F recordings at the three recording regions. Shocks of both polarities were tested. delta F during the shock was expressed as a percentage of the fluorescence change during the S1 upstroke action potential amplitude (the S1 Fapa), ie, delta F/Fapa%. In the macroscopic study, the magnitudes of delta F/Fapa% from recording spots 1 to 9, numbered from the left to the right ventricular electrodes, were 77 +/- 41%, 46 +/- 32%, 32 +/- 27%, 28 +/- 20%, 37 +/- 25%, 24 +/- 20%, 33 +/- 22%, 37 +/- 25%, and 59 +/- 29%, respectively (P < .05 among the nine spots). Depolarization or hyperpolarization could occur near either shock electrode with both shock polarities, but the magnitude of hyperpolarization was 1.8 +/- 0.9 times that of depolarization at the same recording spot when the shock polarity was reversed (P < .01). In the microscopic study, the change in delta F/Fapa% varied significantly over the microscopic regions examined. The maximum values of delta F/Fapa% for hyperpolarizing shocks during diastole reached only 7 +/- 10% of those for shocks during the plateau (P < .01). During diastole, the time until a new action potential occurred after the beginning of the shock was shorter when the membrane was depolarized (1.1 +/- 0.5 ms) than when it was hyperpolarized (12.8 +/- 9.1 ms, P < .01). Conclusions are as follows: (1) A shock can induce either hyperpolarization or depolarization. (2) Hyperpolarization or depolarization during a shock can occur near either the anodal or cathodal shock electrode. (3) Variation of delta F/Fapa% exists within a microscopic region.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗

PubMed1995

Glomerular mesangial cell altered contractility in high glucose is Ca2+ independent.

In diabetes, loss of renal arteriolar smooth-muscle cell contractility leads to intraglomerular hypertension. In glomeruli isolated from streptozotocin (STZ)-induced diabetic rats, the mesangial cells (smooth muscle-like) display loss of contractile responsiveness to angiotensin II. This study examines the mechanistic relationship between altered mesangial cell contractility and vasopressor hormone-stimulated Ca2+ signaling in high glucose. Glomeruli were isolated from normal or STZ-induced diabetic rats to observe ex vivo mesangial cell contractile function. Also, rat mesangial cells were cultured (10-20 passages) in normal (5.6 mmol/l) or high (10-25.6 mmol/l) glucose for 1-5 days. Reduction of glomerular volume and decreased planar surface area of cultured mesangial cells in response to vasoconstrictor stimulation over 60 min were measured by videomicroscopy and personal computer-based morphometry. Contraction of glomeruli isolated from STZ-administered rat in response to endothelin (ET)-1 (0.1 mumol/l) or the Ca2+ ionophore A23187 (5 mumol/l) was impaired significantly compared with that in normal glucose. In the presence of arginine vasopressin (AVP) (1.0 mumol/l) or ET-1 (0.1 mumol/l), mesangial cells demonstrated a dose-dependent loss of contractile response to increasing glucose concentrations (5.6-25.6 mmol/l) within 24 h of high-glucose exposure, which was sustained for 5 days. Mesangial cells in high glucose were consistently smaller in size compared with those in normal glucose. Mesangial cells were preloaded with myo-[2-3H]inositol and intracellular [3H] inositol phosphate release in response to AVP (1.0 mumol/l) was analyzed by Dowex chromatography. Comparing cells in normal (5.6 mmol/l) verus high (25.6 mmol/l) glucose, we observed no significant difference in stimulated inositol phosphate levels from 10 to 60 s.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

[Interference of selenium germanium and calcium in carcinogenesis of colon cancer].

We studied DMH induced colon cancer in 120 wistar rats, which were divided into 8 groups based on different diets. They were killed and autopsied on 4 weeks after the last injection of DMH. The tumors in various organs including its characteristics, number, site, histological types and ultrastructural changes were observed. The results showed that high fat diet has a significant effect on DMH induced colon cancer. Selenium and calcium can inhibit the effect of DMH and decrease the incidence of colon cancer. Selenium can also interfere the effect of high fat diet but germanium has no effect on colon carcinogenesis.

Animals↗

PubMed1995

High glucose alters actin assembly in glomerular mesangial and epithelial cells.

BACKGROUND: Glomerular mesangial and epithelial cell structure and function are maintained by cytoskeletal protein organization and function. To determine whether the diabetic milieu alters filamentous (F-) actin assembly, the spatial distributions and content of F- and monomeric (G-) actin were analyzed in rat mesangial and glomerular epithelial cells (10 to 15 passages) cultured for 5 days in high (22.4 mM) or normal (5.2 mM) glucose and in cells of whole glomeruli isolated from streptozotocin-treated diabetic or normal rats. EXPERIMENTAL DESIGN: Cells were labeled with the fluorescent probes rhodamine-phalloidin and FITC-DNase-1 specific for F- and G-actin, respectively. The average pixel intensities per cell were measured using dual channel confocal laser scanning microscopy (N = 60 cells per group). Total and G-actin were measured in mesangial cells by a spectrophotometric-based DNase-1 inhibition assay. RESULTS: In response to endothelin-1, 0.1 microM, vasopressin 1.0 microM, or angiotensin II 1.0 microM, mesangial cells cultured in normal glucose displayed partial disassembly of F-actin characterized by decreased fluorescence intensity (microfilament bundle pattern changed to network) with no change in G-actin fluorescence. In high glucose, but not mannitol (22.4 mM), partial disassembly of F-actin and loss of response to the agonists were observed. In high glucose, the F-actin content (micrograms/mg cellular protein) was reduced significantly with no change in absolute G-actin compared with normal glucose exposure. The effect of high glucose on mesangial cell actin was reversed by returning the cells to normal glucose for 2 days, stimulation with insulin 2 micrograms/ml, or with a protein kinase C inhibitor. Mesangial cells in high glucose were smaller in planar area and exhibited loss of contractile response to endothelin-1 (0.1 microM) or vasopressin (1.0 microM) measured by videomicroscopy. High glucose-induced F-actin disassembly, possibly due to activated protein kinase C, could account for smaller cell size and lack of response to vasopressor agents. Glomerular epithelial cells cultured in normal glucose demonstrated F-actin disassembly and increased G-actin fluorescence intensity in response to A23187 (5 microM) or bradykinin (10 nM). When cultured in high glucose, but not mannitol, increased epithelial G-actin fluorescence and loss of F- and G-actin response to agonists were observed. Although stimulation with insulin reversed the high glucose effect on epithelial G-actin, F-actin remained unresponsive to agonists. The cells of glomeruli isolated from the diabetic rat displayed the same increase in G-actin, no change in F-actin fluorescence, and loss of response to agonist stimulation as observed in cultured epithelial cells. CONCLUSIONS: These findings suggest that high glucose alters actin assembly in both glomerular mesangial and epithelial cells in vitro and in vivo, possibly contributing to cellular dysfunction in early diabetes.

Actins↗

PubMed1995

[A study on the relationship between in-door air pollution and chronic obstructive pulmonary disease in Xuanwei County].

A cross-sectional study was conducted to explore the relationship between in-door air pollution caused by different fuels for domestic use and chronic obstructive pulmonary disease (COPD) in local population. A total population of 10892 were sampled and analyzed. Results showed in-door air pollution caused by coal-burning was the major risk factor for COPD in Xuanwei County. The risk of residents using soft coal and anthracite to suffer from COPD was 4.36 and 1.55 times, respectively, higher than in those using fire wood.

Air Pollution, Indoor↗

PubMed1995

[Changes in serum IL-2 and sIL-2R levels in patients with primary hepatic carcinoma before and after treatment and their clinical significance].

Serum IL-2 and sIL-2R levels were measured with sandwith ELISA assay before and after surgery or transarterial embolization in 19 cases of primary hepatic carcinoma. The results show that pretreatment IL-2 levels of patients were significantly lower and sIL-2R expression was higher than those of normal control. IL-2 levels of patient were increased and sIL-2R expression was decreased after treatment. The results suggest that the changes of IL-2 level and sIL-2R expression may be closely related to treatment, recurrence and prognosis of patients with primary hepatic carcinoma.

Adult↗

PubMed1995

[Establishment of three-dimensional finite element models by using a series of plane section images processed with an image analysis system].

The geometric similarity and mesh dividing of finite element models directly create an effect on the results of analysis when a theoretical stress analysis is performed by the use of finite element method. The model is routinely established by means of sectioning the specimen. In this paper, a series of plane section CT images of the teeth and mandible, an image analysis system and a specially designed software for modeling three-dimensional finite element were used to establish a three-dimensional finite element model. It is a new preprocessing method for finite element applications in the field of oral biomechanism. The technique is characterized by the advantages of high similarity of the model to specimens and no damage to specimens; it is simple and easy. The images and figures can be repetitively used.

Biomechanical Phenomena↗

PubMed1995

[The cytopathologic diagnosis of cervical lesions and uterocervical carcinomas].

Fifty one cases of Papanicolaou grade, I, II, III and 49 of IV, V were studied for cytopathologic diagnosis in cervical and uterine curet smears. The cervical glandular erosion, metaplasia and cervical intraepithelial neoplasia, as well as histologic types of carcinomas, which were not distinguished by diagnosis of Papanicolaou grades, were determined by cytopathologic diagnosis. Therefore, the papanicolaou method of cytologic diagnosis should be gradually replaced by cytopathologic diagnosis.

Carcinoma, Squamous Cell↗

PubMed1995

[Clinicopathologic characteristics of primary liver cancer in patients younger than 35 years].

To investigate clinicopathologic characteristics of primary liver cancer (PLC) in young adults, 77 patients younger than 35 years were compared with 603 patients older than 35 years during the same period. In the young patients, PLC showed a low incidence of PLC detected at mass survey (young 15.6% versus older 28.7%, P < 0.05); a low incidence of hepatitis history (young 36.8% versus older 66.3%, P < 0.01); a high incidence of positive hepatitis B virus surface antigen (HBsAg) (young 79.2% versus older 67.6%, P < 0.05); a low incidence of associated cirrhosis (young 64.9% versus older 90.7%, P < 0.01); larger tumor size (PLC > 5cm; young 87.0% versus older 73.0%, P < 0.01); a more advanced stage of the disease in TNM classification (stage III; young 29.9% versus older 18.2%, P < 0.05). It is suggested that hepatitis B virus (HBV) may play an important role in the development of PLC without associated liver cirrhosis in the young patients. A close periodic surveillance of young adults with a positive HBsAg is important to detect PLC at an early stage.

Adolescent↗

PubMed1995

[Expression of Epstein-Barr virus encoded small RNA-1 and latent membrane protein-1 in midline T-cell lymphomas].

Nine cases of midline T-cell lymphoma (MTL) were studied for expression of Epstein-Barr virus (EBV) encoded small RNA-1 (EBER-1) and EBV latent membrane protein-1 (LMP-1) using in situ hybridization and immunohistochemistry respectively. EBER-1 was detected in nuclei of tumor cells in 8/9 cases of MTL and LMP-1 was found on membrane and in cytoplasm of tumor cells in 7/9 cases of MTL. The results show: (1) There is a strong association between EBV and MTL. EBV may play an important role in the pathogenesis of MTL. (2) The detection frequency of EBV in MTL is higher than peripheral T-cell lymphoma from other sites of the body. (3) EBER-1 in situ hybridization and LMP-1 immunohistochemistry are sensitive and reliable in detection of EBV in MTL and the latter is more economic and convenient.

Herpesvirus 4, Human↗

PubMed1995

[The course of malaria control and present status in Zhejiang Province].

Through forty years' sustained efforts in the prevention and treatment of malaria in Zhejiang Province, the malaria incidence dropped from 76.650/000 in the Fifties to 0.910/000 in the Eighties. Three malaria epidemics emerged in 1954, 1962 and 1973, respectively, among them the epidemic in 1962 was the most serious one with 0.88 million cases reported and an incidence of 3300/000. The annual incidence of the overall counties/cities was below 10/000 after 1988. Only 172 malaria cases were found in 1992, the incidence being 0.040/000. No indigenous malaria case was found in 38 counties in 1992, accounting to 43.7% of the total malaria endemic counties. The number of imported malara cases was 3,829, amounting to 89.2% of the total number of cases. Through the spot-check of the Ministry of Public Health in 1993, it was confirmed that the criteria of basic elimination of malaria in the province was attained.

Animals↗

PubMed1995

[An analysis of pathologic features and prognostic factors of 10 cases with pseudomyxoma peritonei].

OBJECTIVE: To investigate the histogenesis and the pathological features of pseudomyxoma peritonei and to analysis its prognostic factors. METHODS: Ten cases with pseudomyxoma peritonei were clinicopathologically studies, with follown-up at least 24 monthes. All histopathological sections and clinical data were reviewed. RESULTS: Seven out of 10 patients had the ovarian mucinous tumors which were bilateral in 5 cases (71.4%). Histopathologically, 4 of 7 cases with ovarian tumor were characterized by the presence of the multifocal bleeding, fragmental necrosis, and occasionally, the striated border on the glandular lumens. The mucinous epithelial cells and mucin invased into the peritonei, destroyed normal structure, and formed the desmoplasia. Four patients died of pseudomyxoma peritonei, all with extensive lesions, invasions in the peritonei, and a short recurrent time (mean, 12.0 monthes) after presentation. CONCLUSIONS: The histogenesis of pseudomyxoma peritonei is heterogenous, the presence of possible metastases including from the appendix, the colon and other organs. The most important factors of the prognosis should include the extent of initial lesions, the presence of invasion in the peritonei and a rapid recurrence.

Adult↗

PubMed1995

[Genetic epidemiological studies on male lung cancer].

Data of nuclear families of 194 male proband with lung cancer and 176 controls were analyzed to study its genetic etiology in Xuanwei County of Yunnan Province. Results showed risk of lung cancer in the relatives (parents and siblings) of the proband was 1.78 times as of controls, with a statistically significant difference, and risks in parents and female relatives of the proband were 2.90 and 2.43 times as in controls, respectively, both with a statistically significant difference. Heritability of male lung cancer was 24.68%. It indicated genetic susceptibility to lung cancer in females was higher than that in males and played an important role in the etiology of lung cancer.

Adult↗

PubMed1995

[cDNA clones of differential expression between human normal liver tissue and hepatocarcinoma].

Using mRNA differential display technique, we studied the interesting cDNA clones of differential expression between human normal liver and hepatocarcinoma. mRNA extracted from normal liver tissue and hepatocarcinoma cell line Hep3B were subjected to RT-PCR reaction with ten combinations of two 3' primers and five 5' primers. After subjecting these PCR products to labelling with 35S(a)-dATP, PAGE and autoradiography, we obtained a lot of cDNA clones of differential expression. Thirty-one of these clones were partially sequenced. It was shown that 30 clones had no sequences matched with GenBank except one. Dot hybridization showed that 2 cDNA clones were overexpressed in liver cancer tissue and 1 cDNA clone was overexpressed in normal liver tissue. The further characterization of these cDNA clones is in progress.

Carcinoma, Hepatocellular↗

PubMed1995

[A clinicopathological analysis of 11 patients with pulmonary sclerosing hemangioma].

Eleven cases of pulmonary sclerosing hemangioma proved by operation and pathological examination were reported. All patients showed at least 3 different typical pathological features and infiltration of the histocytes and dilated blood vessels with papillary projections were the commonest manifestations. The clinical manifestations, pathology and histogenesis were discussed and related literature reviewed.

Adult↗