Biomedical subjects

Z Shen

Publications and source records attributed to Z Shen.

At least 199 records · Page 11Linked to original sources

PubMed1997

Rad51 immunocytology in rat and mouse spermatocytes and oocytes.

On the assumption that Rad51 protein plays a role in early meiotic chromosomal events, we examine the location and time of appearance of immuno-reactive Rad51 protein in meiotic prophase chromosomes. The Rad51 foci in mouse spermatocytes appear after the emergence of, and attached to, short chromosomal core segments that we visualize with Cor1-specific antibody. These foci increase in number to about 250 per nucleus at the time when core formation is extensive. The numbers are higher in mouse oocytes and lower in rat spermatocytes, possibly correlating with recombination rates in those cases. In the male mouse, foci decrease in number to approximately 100 while chromosome synapsis is in progress. When synapsis is completed, the numbers of autosomal foci decline to near 0 while the X chromosome retains about 15 foci throughout this time. This stage coincides with the appearance of testis-specific histone H1t at mid- to late pachytene. Electron microscopy reveals that at first Rad51 immunogold-labeled 100 nm nodules are associated with single cores, and that they come to lie between the chromosome cores during synapsis. It appears that these nodules may be the homologs of the Rad51-positive early nodules that are well documented in plants. The reciprocal recombination-correlated late nodules appear after the Rad51 foci are no longer detectable. The absence of Rad51 foci in the chromatin loops suggests that in wild-type mice Rad51/DNA filaments are restricted to DNA at the cores/synaptonemal complexes. The expected association of Rad51 protein with Rad52 could not be verified immunocytologically.

Animals↗

PubMed1997

Freehand three-dimensional echocardiography for measurement of left ventricular mass: in vivo anatomic validation using explanted human hearts.

OBJECTIVES: We sought to validate freehand three-dimensional echocardiography for measuring left ventricular mass and to compare its accuracy and variability with those of conventional echocardiographic methods. BACKGROUND: Accurate measurement of left ventricular mass is clinically important as a predictor of morbidity and mortality. Freehand three-dimensional echocardiography eliminates geometric assumptions used by conventional methods, minimizes image positioning errors using a line of intersection display and increases sampling of the ventricle. Preliminary studies have shown it to have high accuracy and low variability. METHODS: Twenty-eight patients awaiting heart transplantation were examined by conventional and freehand three-dimensional echocardiography. Left ventricular mass was determined by the M-mode ("Penn-cube") method, the two-dimensional truncated ellipsoid method and three-dimensional surface reconstruction. The ventricles of 20 explanted hearts were obtained, trimmed and weighed. Echocardiographic mass by each method was compared with true mass by linear regression. Accuracy, bias and interobserver variability were calculated. RESULTS: For three-dimensional echocardiography, the correlation coefficient, standard error of the estimate, root mean square percent error (accuracy), bias and interobserver variability were 0.992, 11.9 g, 4.8%, -4.9 g and 11.5%, respectively. For the two-dimensional truncated ellipsoid method they were 0.905, 38.5 g, 15.6%, 15.4 g and 23.3%. For the M-mode ("Penn-cube") method they were 0.721, 96.9 g, 53.0%, 109.2 g and 19.5%. CONCLUSIONS: Freehand three-dimensional echocardiography for measurement of left ventricular mass has high accuracy and low variability and is superior to conventional methods in hearts of abnormal size and geometry.

Adult↗

PubMed1997

Freehand three-dimensional echocardiography for determination of left ventricular volume and mass in patients with abnormal ventricles: comparison with magnetic resonance imaging.

OBJECTIVE: The objective of this study was to validate the freehand three-dimensional echocardiographic method in patients with abnormal ventricular geometry compared with two-dimensional echocardiography using magnetic resonance imaging as a standard. BACKGROUND: Two-dimensional echocardiographic methods for estimating left ventricular volume and mass in clinical use today are limited by inaccuracies and variations caused by use of geometric assumptions and errors in image plane positioning. Freehand three-dimensional echocardiography with operator guidance by a "line of intersection" display eliminates these assumptions and errors. This method of volume and mass computation has been validated as highly accurate and reproducible in healthy subjects. METHODS: Left ventricular end-systolic and end-diastolic volumes and myocardial mass were determined by freehand three-dimensional echocardiography, by conventional two-dimensional echocardiography using the apical biplane summation of discs method (volume) and the truncated ellipsoid method (mass), by M-mode echocardiography using the Penn method (mass), and by magnetic resonance imaging in 30 patients selected only for the presence of an abnormal ventricle. Results were compared by means of linear regression and the Bland-Altman method of analysis. RESULTS: There was excellent correlation, low bias, and low variability between three-dimensional echocardiography and magnetic resonance imaging for end-diastolic volume (r = 0.90, standard error of the estimate = 31.8 ml, bias = -28.4 ml), end-systolic volume (r = 0.93, standard error of the estimate = 24.1 ml, bias = -13.1 ml), and mass (r = 0.90, standard error of the estimate = 27.3 gm, bias = -22.6 ml). Two-dimensional echocardiography was less accurate and more variable as follows: end-diastolic volume (r = 0.70, standard error of the estimate = 39.8 ml, bias = -33.5 ml), end-systolic volume (r = 0.78, standard error of the estimate = 31.2 ml, bias = -26.7 ml), and mass (r = 0.80, standard error of the estimate = 37.3 gm, bias = 28.9 ml). M-mode echocardiography mass determination (Penn method) was least accurate and most variable (r = 0.075, standard error of the estimate = 78.3 gm, bias = 78.3 gm). CONCLUSIONS: Freehand three-dimensional echocardiography is a method of high accuracy and low variability for computing left ventricular volume and mass in clinical patients with abnormal ventricles. It is superior to conventional one- and two-dimensional echocardiography. The improvement achieved is attributed to elimination of geometric assumptions and image plane positioning errors and additional sampling of the ventricle.

Adolescent↗

PubMed1997

Cell cycle-dependent protein expression of mammalian homologs of yeast DNA double-strand break repair genes Rad51 and Rad52.

Recently, human and rodent homologs of yeast repair genes Rad51 and Rad52 have been identified and proposed to play roles in DNA double-strand break (DSB) repair. In this study, cell cycle-dependent expression of human and rodent RAD51 and RAD52 proteins was monitored using two approaches. First, flow cytometric measurements of DNA content and immunofluorescence were used to determine the phase-specific levels of RAD51 and RAD52 protein expression in irradiated and control populations. The expression of both proteins was lowest in G0/G1, increased in S and reached a maximum in G2/M. No difference was found in the whole-cell level of RAD51 or RAD52 protein expression between gamma-irradiated and control cell populations. Second, cell cycle-dependent protein expression was confirmed by Western analysis of populations synchronized in G0, G1 and G2 phases. Analysis of V3, a hamster equivalent of SCID, indicates that the protein level increases of RAD51 and RAD52 from G0 to G1/S/G2 do not require DNA-PK.

Amino Acid Sequence↗

PubMed1997

Helicobacter rodentium sp. nov., a urease-negative Helicobacter species isolated from laboratory mice.

A spiral-shaped bacterium with bipolar, single, nonsheathed flagella was isolated from the intestines of laboratory mice. The organism grew at 37 and 42 degrees C under microaerobic and anaerobic conditions, did not hydrolyze urea, was weakly positive for catalase and oxidase, reduced nitrate to nitrite, did not hydrolyze indoxyl acetate or hippurate, and was resistant to cephalothin and nalidixic acid. This is the first urease-negative, murine Helicobacter spp. isolated from intestines. Also, Helicobacter pullorum and this bacterium are unique among the genus Helicobacter in having nonsheathed flagella. The new bacterium appears to be part of the normal intestinal flora; although its pathogenic potential is unknown, this organism was also isolated from scid mice with diarrhea that were co-infected with Helicobacter bilis. On the basis of 16S rRNA gene sequence analysis data and biochemical and phenotypic criteria, the new organism is classified as a novel helicobacter, for which we propose the name Helicobacter rodentium. The type strain is MIT 95-1707 (= ATCC 700285).

Animals↗

PubMed1997

Diagnosis of Helicobacter pylori infection in a colony of rhesus monkeys (Macaca mulatta).

Twenty-three young adult rhesus monkeys from China were evaluated for the presence of Helicobacter pylori. Gastric body and antral biopsy samples were tested for H. pylori by PCR analysis, culture, rapid urease testing, and histologic evaluation. Serologic testing to detect H. pylori immunoglobulin G (IgG) antibodies was performed by using a commercially available human-based enzyme-linked immunosorbent assay (ELISA) test and an ELISA test which utilized homologous H. pylori antigens and an anti-rhesus IgG conjugate. PCR analysis with H. pylori-specific 26-kDa protein primers detected H. pylori in 21 of the 23 rhesus monkeys (91%). Culture testing identified the organism in 12 of the 23 animals (52%). Rapid urease tests were positive for all animals. H. pylori was diagnosed by histological examination in 11 of 23 monkeys (48%). Of the 21 monkeys positive for H. pylori by PCR, only 3 (14%) had positive results by the commercial ELISA test, yielding a sensitivity of 14%, a specificity of 100%, and an accuracy of 22%. However, 19 of the 21 PCR-positive animals (90%) had positive results by the ELISA test with homologous rhesus H. pylori antigen and anti-monkey conjugate, with predicted index values greater than or equal to 0.7 considered positive and values between 0.5 and 0.7 considered equivocal. This test had a sensitivity of 90%, a specificity of 100%, and an accuracy of 91%. Therefore, the ELISA test with rhesus monkey origin components was more accurate for detecting infected animals than the human-based ELISA.

Animals↗

PubMed1997

P2U purinergic receptor inhibits apical IsK/KvLQT1 channel via protein kinase C in vestibular dark cells.

Vestibular dark cells (VDC) are known to electrogenically secrete K+ via slowly activating K+ (IsK) channels, consisting of IsK regulatory and KvLQT1 channel subunits, and the associated short-circuit current (Isc) is inhibited by agonists of the apical P2U (P2Y2) receptor (J. Liu, K. Kozakura, and D. C. Marcus. Audit. Neurosci. 2: 331-340, 1995). Measurements of relative K+ flux (JK) with a self-referencing K(+)-selective probe demonstrated a decrease in JK after apical perfusion of 100 microM ATP. On-cell macropatch recordings from gerbil VDC showed a decrease of the IsK channel current (IIsK) by 83 +/- 7% during pipette perfusion of 10 microM ATP. The magnitude of the decrease of Isc by ATP was diminished in the presence of inhibitors of phospholipase C (PLC) and protein kinase C (PKC), U-73122 and GF109203X. Activation of PKC by phorbol 12-myristate 13-acetate (PMA, 20 nM) decreased IIsK by 79 +/- 3% in perforated-patch whole cell recordings, whereas the inactive analog, 4 alpha-PMA, had no effect. In contrast, elevation of cytosolic Ca2+ concentration by A-23187 increased the whole cell IIsK. The expression of the isk gene transcript was confirmed, and the serine responsible for the species-specific response to PKC was found to be present in the gerbil IsK sequence. These data provide evidence consistent with a direct effect of the PKC branch of the PLC pathway on the IsK channel of VDC in response to activation of the apical P2U receptor and predict that the secretion of endolymph in the human vestibular system may be controlled by PKC in the same way as in our animal model.

Adenosine Triphosphate↗

PubMed1997

[Microsatellite instability in nephroblastoma and its relationship to clinicopathological variables].

OBJECTIVE: To study the relationship between microsatellite instability (MSI) and clinicopathological variables in nephroblastoma. METHODS: 2 microsatellite repeat sequences AR (chromosome X), UT762(chromosome 21) were examined in normal and tumor pairs from 50 nephroblastoma patients by PCR and denatured polyacrylamide gel electrophoresis. RESULTS: The MSI positive for AR and UT loci were 14/50 and 10/50 respectively in nephroblastoma. MSI positive for both AR and UT occurred in 2 cases. According to NTWS-III categorization, stage I & II belong to early stage and stage III & IV belong to late stage, the MSI for this series were 16/38 and 6/12 for early and late stages. According to the NWTI-II categorization, the MSI of this series for favorable and non-favorable histology were 71% and 33% respectively. CONCLUSIONS: Analysis of MSI may have some significance in discriminating the malignant status of nephroblastoma.

Chromosomes, Human, Pair 21↗

PubMed1997

[Dermatomyositis and malignancy of the pharynx (report of 3 cases)].

Three patients with dermatomyositis are reported, two of them had suffered from carcinoma of the nasopharynx and the last one suffered tonsillar carcinoma. The diagnosis the therapy, the prognosis and the relationship between dermatomyositis and malignancy were discussed in detail in this paper. The author emphasised that careful examination of the nose and pharynx would be very important for the patient with dermatomyositis.

Carcinoma, Squamous Cell↗

PubMed1997

[Investigation on nitrosamines in the diets of the inhabitants of high-risk area for esophageal cancer in the southern China and analysis of the correlation factors].

Nan'ao County in Guangdong Province was an esophageal cancer high-risk area in the southern China. Of the suspected etiological factors in the environment, N-nitrosamines and their precursors have been received the most attention. 55 samples of the diets ingested by the inhabitants were collected and tested for volatile N-nitroso compounds and for their precursors by GC-TEA. Five kinds of N-nitrosamines (NDMA, NDEA, NPYR, NPIP and NMBzA) were detected in the samples. The average level of them was 312.0 micrograms/kg(median). The day intake of the nitrosamines was 286.5 micrograms/head/day. By the computerized stepwise regression analysis and curve fitting, we studied the correlation among the nitrosamines, the precursors and the major food items. It demonstrated that a relatively high content of volatile N-nitrosamines was present in the diets collected in the area.

Carcinogens↗

PubMed1997

[Pharmacokinetics and efficacy of low-dose all-trans retinoic acid in the treatment of acute promyelocytic leukemia].

A clinical trial was conducted in order to evaluate the therapeutic effect and side effects of low-dose all-trans retinoic acid (ATRA) in the treatment of acute promyelocytic leukemia (APL). First of all, we compared the pharmacokinetic features in normal individuals with a single oral dose of ATRA at 15 mg/m2 and 45 mg/m2, respectively. The results showed that maximal plasma concentration with oral ATRA at 15 mg/m2 was high enough (10(-6) mol/L) to induce APL cell differentiation. Based on these results, 27 cases of de novo APL patients were treated with oral ATRA at a dose of 15-20 mg/m2/day and 24 of the 26 (92%) evaluable cases achieved clinical complete remission (CR) after 13 to 67 dyas of ATRA treatment. No patient experienced retinoic acid syndrome (RAS) and DIC. The Cmax with a single dose of ATRA on day 1 of treatment and immediately after obtaining of CR with ATRA in three cases demonstrated similar values in one patient and an about 2 fold decrease in two patients. Moreover comparison with a relatively well-matched previous group of 20 APL patients treated with high-dose ATRA showed that low-dose ATRA is as effective as high-dose in treating APL patients and may provide the advantages of decrease of the degree of hyperleukocytosis and side effects.

Adolescent↗

PubMed1997

[Expression of p53 in nephroblastoma and neuroblastoma].

We studed on the expression of p53 in 48 nephroblastomas and 32 neuroblastomas wit, immunohistochemical method of avidinbiotinperoxidase complex. 11 of the nephroblastomas were positive and all neuroblastomas were negative. Statistical analysis revealed that abnormal expression of p53 was significantly correlated with NWTS--II classification, NWTS--III clinical pathology stages and metastasis of nephroblastoma. The results indicate that abnormal expression of p53 is not only involved in the development, but also in the differentiation and metastasis of nephroblastoma. Therefore, detection of p53 expression may have significant clinical importance in the evaluation of prognosis of nephroblastoma. However, the absence of expression of p53 in neuroblastomas suggests that the inactivation of this gene does not play a significant role in the tumor's occurring and progression.

Child↗

PubMed1997

[Prognosis and adjuvant chemotherapy of axillary node-negative breast cancer patients].

The significance of postoperative chemotherapy was studied in 439 cases of unilateral primary breast cancer which were proved histologically with no axillary lymph node metastasis. The survival rate was analyzed by life table method. The prognosis of node negative breast cancer patients was mainly associated with tumor size. 10 year survival rate of patients with tumor less than 3 cm treated operativel and by operation combined with chemotherapy was 92.60% and 94.13% respectively. If tumor size was larger than 3 cm, the ten year survival rate of the patients treated operatived was 79.89%, and that of the patients with combined theropy 96.02%. The prognosis was statistically different between the two groups. As to age, status of menopause, pathologral type, kind of surgery and status of ER, the prognosis of patients treated by combined therapy was better than that of patients treated by operation alone. The postoperative chemotherapy was not significantly beneficial to breast cancer patients with tumor less than 3 cm.

Adenocarcinoma↗

PubMed1997

[Male breast cancer: experience with 42 cases].

Data were collected on 42 men with breast cancer treated at department of surgery, cancer hospital in Shanghai between 1960 to 1996. We studied several clinical features and the importance of established prognostic factors. Observation for 76 months showed the 5 year survival rate was 57.1%, and the total survival was 64.3%. Prognostic indicator analysis showed that only axillary lymph node status proved to have a prognostic impact. Tumor size, age did not show any prognostic influence. Because of less cases, we can not use Cox's regression model to do multivariate analysis.

Adult↗

PubMed1997

[Immunohistochemical and quantitative analysis of expression of basement membrane in squamous cell carcinoma of the oral cavity].

Fifty seven cases of oral squamous cell carcinoma (OSCC) were studied by immunohistochemical ABC method using type IV collagen and laminin antibodies and computer image analysis system to investigate the expression of basement membrane and its relation to clinicopathologic characteristics of the OSCC. The results demonstrated that: 1. in OSCC there were defects basement membrane in continuity of varying extents to complete loss of; 2. there was no correlation between the loss of basement membrane and tumor clinical stage (P > 0.05) by computer image analysis, while there was a highly significant correlation between the loss of basement membrane and histologic grading (P > 0.05). The well-differentiated tumor was associated with a low frequency of basement membrane loss. Therefore, the expression of basement membrane may be a useful parameter to evaluate tumor histologic differentiation.

Basement Membrane↗

PubMed1997

[Cox proportion hazard model multivariate analysis of prognosis of 1,484 axillary node-negative breast cancer patients].

OBJECTIVE: To study the prognosis of axillary node-negative breast cancer patients. METHODS: The data were analyzed in 1,484 consecutive axillary node-negative breast cancer patients. Twenty-two individual variables were evaluated statistically using the cumulative survival rate by the computer's Cox multivariate analysis model. RESULTS: Menopausal status, times of pregnancy, duration before diagnosis, pregnancy-associated, tumor size, intramammary lymph node, postoperative radiotherapy and postoperative adjuvant tamoxifen therapy were independent predictors of prognosis. CONCLUSION: Parts of high risk group among axillary node-negative breast cancer patients could be identified by clinical parameters. Postoperative radiotherapy or ovarian ablation was not indicated for axillary node-negative breast cancer patients. Tamoxifen as postoperative adjuvant therapy should not be restricted to postmenopausal or ER-positive patients. The selection of high risk patients with axillary node-negative breast cancer who should receive adjuvant chemotherapy remains to be investigated at present.

Adult↗

PubMed1997

[The development of ECG trans-telephone popular monitoring system].

In this essay a new kind of ECG telemetry and monitoring system based on public telephone network is presented, which is able to transfer four channels of ECG of two patients to monitoring center sited at hospital synchronizingly. At the same time doctors may make diagnosis and give instruction for treatment. The system has the functions of real time sample, reviewing, freezing, store, windows, and printing, etc.

Electrocardiography↗

PubMed1997

Estrogen receptor-negative breast cancer cells transfected with estrogen receptor exhibit decreased tumour progression and sensitivity to growth inhibition by estrogen.

Breast cancer containing estrogen receptors (ER) are responsive to antiestrogen treatment and have a better prognosis compared with ER-negative tumors. The loss of estrogen receptors appears to be associated with a progression to less-differentiated cells. We transfected the human ER into the ER-negative breast cancer cell line MDA-MB-231 cells. We found that expression of adequate ER is strong associated with the ability of human breast cancer cell growth inhibition and progression. Compared with nontransfected or mock-transfected cells, ER-transfected cells exhibited growth slower, forming smaller colonies in soft agar and growth inhibited by estrogen and tamoxifen. Therefore reactivation or transfection of the estrogen receptor gene can be considered as therapeutic approaches to hormone-independent breast cancer.

Breast Neoplasms↗