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Biomedical subjects

Y Shen

Publications and source records attributed to Y Shen.

At least 199 records · Page 11Linked to original sources
PubMed2000

[Initial experience of cardiac multidetector-row CT using a multisector reconstruction algorithm: studies of normal volunteers].

Multisector reconstruction is a newly devised algorithm that realizes cardiac images of high temporal resolution (0.13 msec minimum) at arbitrary phases of the cardiac cycle without degrading the signal-to-noise ratio. In this study, we examined the image quality of volunteers' examinations. Multisector reconstruction was found to be a feasible tool, providing excellent cardiac images almost without motion artifact. In addition to detecting coronary calcium, with the advantage of multidetector-row CT for good z-axis resolution and for volumetric data acquisition of the entire heart within a single breath hold, this technique could provide 3D images beneficial to the analysis of cardiac motion.

Adult↗
PubMed2000

[Analysis of dynamic stress for human skull-brain under impact loading with acceleration and deceleration].

In this paper, we measure and analyze the changes of dynamic stress in human skull-brain under impact loading. By applying the frequency responding function and coherence function produced by the pressure of impact wave at each point on skull, and by use of the viewpoint of biomechanics, we further research into brain injuries and have got some data which cannot be obtained in clinical setting.

Acceleration↗
PubMed2000

[Analysis of wavelet scalogram of blood flow ultrasonic Doppler signal].

OBJECTIVE: To study the power spectrum density of blood flow ultrasonic Doppler signal using wavelet analysis. METHOD: Doppler signal of blood flow in human common carotid artery was studied with wavelet scalogram analysis, an affine smoothing Wigner-Ville transform with a constant "Q" character. RESULT: Wavelet scalogram of blood flow ultrasonic signal had a higher distinguishability than STFT spectrogram in the low frequency portion, but had poorer decussation terms than spectrogram. CONCLUSION: It is practicable to estimate the spectrum of Doppler signals of blood flow by the wavelet analysis method. And this can be used in low speed blood flow for higher resolution of spectrum in the low frequency portion.

Aerospace Medicine↗
PubMed2000

[Comparative study of metastasis-associated characteristics of tumor cells with different metastatic capacities].

OBJECTIVE: To investigate the relationship between metastatic potential and other biological properties of tumor cells. METHODS: Three human colon carcinoma cell lines WiDr, HT-29 and HT-29b with similar genetic background were hetero-transplanted into nude rats by mesenteric intravenous inoculation and their dissemination was observed. Homotypic aggregation, target organ colonization, cell proliferation and apoptosis, expression of c-erbB-2, EGFR, p53 and mucin, CA19-9 and CEA of tumor cells of these 3 cell lines were comparatively studied by using three dimensional spheroid cell culture, TUNEL and immunocytochemistry. RESULTS: The three cell lines differed significantly in their metastatic capacities. HT29b and HT29 cells metastasized to the liver, lungs and other parts of the body but the metastasis was more marked in the former than in the latter. WiDr cells did not metastasize at all. In 50%-60% of nude rats with HT-29 and HT29b xenografts, tumor cells were colonized in the liver while no such colonization was seen in rats with WiDr xenograft. The metastatic potential was found to be negatively correlated with the in vitro homotypic aggregating capacity of the tumor cells. The tumor cells with high metastatic potential were found to have higher cell proliferation index but lower cell apoptosis index as compared to those with low metastatic potential. Higher expression of EGFR and mutant p53 in tumor cells with high than in those with low metastatic potential was also observed. No such difference existed in the expression of mucin, CA19-9 and CEA. CONCLUSION: The metastatic capacity of colon carcinoma is associated with such biological properties of tumor cells as homotypic adhesion, target organ colonization, status of cell proliferation and apoptosis, and expression of EGFR and mutant p53.

Animals↗
PubMed2000

[Retrospective cohort study on the prognosis of chronic myeloid leukemia].

OBJECTIVE: To evaluate the prognostic factors of chronic myeloid leukemia (CML). METHODS: Survival curves were plotted according to the Kaplan-Meier method. Variables associated with prognosis were analyzed by Logrank test. A multivariate analysis of prognostic factors was performed using stepwise Cox model. RESULTS: Of the total 158 patients, the median survival time was 1,480 days. 5 years survival rate was 47.1% (95% CI, 36.7% - 56.9%). 10 years was 24.8% (95% CI, 15.0% - 35.8%). The predominant blastic crisis type is myeloblastic, myelomonocytic or monocytic(77.5%). The period from chronic phase to blastic phase was equal in myelosuppressive therapy group, non- myelosuppressive therapy group or altretamine (HMM) group. After evaluated by stepwise Cox's regression model, age>or=50 years, bone marrow blasts>or=0.05, bone marrow basophilic>or=0.05, Ph chromosome negative and HMM treatment were associated with poor prognosis. Hydroxyurea was always associated with longer survival. CONCLUSION: Age, Ph chromosome, bone marrow blasts and basophilic, and various treatment affected the survival of CML.

Adult↗
PubMed2000

[Total meso-rectal excision in low anterior resection with double stapling technique].

OBJECTIVE: To elucidate the value of total meso-rectal excision (TME) in low anterior resection with double stapling technique. METHODS: During January 1993 to October 1998, 306 cases of rectal lesions were treated by total meso-rectal excision in low anterior resection (LAR) with double stapling technique. Among the patients with rectal cancer, 235 (78.86%) were treated by low anterior resection and 97 (41.28%) by ultra-low anterior resection. RESULTS: No operative death was noted, and anastomotic leakage occurred in 9 (2.94%) patients. Ureter injury occurred in 2 (0.65%) patients. 32 (10.46%) patients suffered from anastomotic stenosis, 31 mm diameter of stapler for 27 (12.68%) patients and 33 mm diameter of stapler for 5 patients (5.38%). Local recurrence occurred in 20 (6.71%) patients: Dukes'B 4 (2.33%) patients, Dukes'C 9 (12.5%) patients, and Dukes'D 7 (53.85%) patients. CONCLUSIONS: Total meso-rectal excision can effectively reduce the local recurrence rate after LAR with double stapling technique. Since the recurrence is closely related to the stage of the disease, early detection, early diagnosis and early treatment are extremely important.

Adult↗
PubMed2000

[Laparoscopic gastric resection].

OBJECTIVE: To modify laparoscopic surgery for gastric diseases. METHODS: From December 1992 to January 1999, 61 gastric laparoscopic operations were performed in our hospital. The age of the patients ranged from 29 to 78 years (mean 57.4). 17 patients had Billroth II gastrectomy, 1 Billroth I gastrectomy, 2 proximal subtotal gastrectomy, 5 highly selective vagotomy, 3 gastrostomy, and 33 resection of gastric submucosal benign tumor. 54 patients (88.5%) underwent complete laparoscopy, and 7 (11.5%) an assisted one RESULTS: The mean operative time was (164.2 +/- 93.5) min, the mean estimated blood loss was (218.3 +/- 166.6) ml, and the mean hospital stay was (6.8 +/- 2.1) days. Flatus was present within 48 hours in 86% of the patients. Two patients had laparoscopic surgery for early gastric cancer, and were followed up for more than 55 months. Postoperative complication were noted in 2 patients, who were cured by reoperation and endoscopy therapy respectively. Only 4 patients required postoperative analgesics. CONCLUSION: Although specific indications need to be defined, laparoscopic surgery is feasible. But long-term follow-up should be made to evaluate its efficacy in treatment of gastric cancer.

Adult↗
PubMed2000

[Reducing incidence and mortality from rectal cancer by polypectomy: a prospective cohort study].

OBJECTIVE: To address the hypothesis that colorectal cancers often arise from precursor lesion(s), either adenomas or non-adenomatous polyps. METHODS: A population-based mass screening for rectal cancer using 15cm rigid endoscopy was conducted in Haining County, Zhejiang province, from 1977 to 1980. Of over 230,000 participants, 4,076 of them were diagnosed with precursor lesions, either adenomas or non-adenomatous polyps, which were then removed. All individuals with precursor lesions were followed and re-examined by endoscopy every two to five years through 1998. RESULTS: After the initial screening, 952 metachronous adenomas and 417 non-adenomatous polyps were detected and removed from the cohort. Furthermore, 27 cases of colorectal cancer were detected and treated. Log-rank tests showed that the years of survival significantly increased among those cancer patients who had undergone mass screening compared to other rectal cancer patients (P < 0.001). According to the population-based cancer registry in Haining County, both age-adjusted incidence and mortality rates from rectal cancer decreased from 1977 to 1996. Observed accumulative incidence and mortality rates decreased to 68.6% and 82.4% comparing with expected numbers during the last 20 years. CONCLUSION: Mass rectal cancer screening in the general population followed by routine endoscopy for high-risk patients could decrease both rectal cancer incidence and mortality rates.

Adenoma↗
PubMed2000

[Drinking water types, microcystins and colorectal cancer].

OBJECTIVE: To assess the relationship between microcystins (a blue-green algal toxin) in drinking water and colorectal cancer. METHODS: Eight townships were randomly selected as study sites in Haining city of Zhejiang province, China. Four hundred and eight colon and rectum carcinoma cases diagnosed from 1977 to 1996 were identified from cancer registry in the study sites. A retrospective survey on types of drinking water of all 408 cases was conducted. Population data and drinking water sources data were provided by local household registration and local health institution, respectively. Water samples from different sources (well, tap-water, river and pond) were collected and microcystins concentrations were measured by an indirect competitive ELISA method. RESULTS: The incidence rates of colorectal cancer were significantly higher among people drinking river or pond water than those who drank well water or tap-water in both males and females. And comparing with other sources to well water, the relative risks (RR) were much higher for people using river water (7.94) and pond water (7.70). The positive detection rates (> 50 pg/ml) of microcystin in well, tap-water, river and pond water were 0.00%, 0.00%, 36.23% and 17.14% respectively. The highest concentrations of microcystins were 1 083.43 pg/ml (river) and 1 937.94 pg/ml (pond) in the positive samples. Microcystins concentrations in river and pond were significantly higher than the concentrations in well and tap water (P < 0.01). The Spearman rank correlation analysis showed that in the study sites, the microcystins concentrations of river and pond water were positively correlated with the incidence of colorectal cancer (r = 0.881, P < 0.01). CONCLUSION: Drinking surface water (river or pond) is one of the risk factors for colorectal cancer. Microcystins may be associated with incidence of colorectal cancer. It is suggested that further study should be carried out to clarify the relationship between colorectal cancer and microcystin in drinking water.

Bacterial Toxins↗
PubMed2000

[Exploration of gene expression profiles of CD(34)(+) hematopoietic stem/progenitor cells based on large scale sequencing].

OBJECTIVE: To set up a large scale sequencing system and explore the gene expression profiles of CD(34)(+) hematopoietic stem/progenitor cells (HSPCs). METHODS: CD(34)(+) cells were isolated from umbilical cord blood and subjected to cDNA library construction. A primary profile of gene expression in HSPCs was emerged by EST sequencing and bioinformatics analyzing. RESULTS: Among 9,866 ESTs thus obtained, 7 476 meaningful ESTs were clustered into 2,060 unique sequence species (USSs), representing 1,054 known gene species and 1,006 unknown gene fragments. The 1054 known genes were divided into 8 categories: (1) hematopoiesis associated: 73, (2) chromatin structure and cell division/apoptosis: 91, (3) signal transduction and receptors: 111, (4) cell structure/mobility: 48, (5) cell/organism defense/homeostasis: 41; (6) Gene expression (transcription, translation and modification): 265, (7) metabolism: 192; and (8) unclassified: 233. CONCLUSION: A gene expression profile including 1,054 known genes and 1006 new gene fragments of HSPCs was primarily obtained, which may lay a basis for the further study on the molecular mechanism of hematopoiesis regulation and provide candidates for new gene cloning.

Antigens, CD34↗
PubMed2000

[The effect of injuries on Fn synthesized by FBs and its implication in wound timing].

cFn synthesized by FBs around the wound was detected by immunochemistry in vitro. Using the method of ELISA, The concentration of cFn in the culture media was observed. The concentration of cFn had no change within 30 minutes after injury, but started to increase after 1 hour of the injury and kept this trend within next five hours after injury. By static analysis, it can be obtained that the concentration of cFn in culture media is time-dependent after injury.

Cells, Cultured↗
PubMed2000

[Motor evoked potentials of upper limbs].

This study aims to explore a method to record and analyze motor evoked potentials (MEP) of upper limbs. Compound muscle action potentials (CMAP) are recorded from abductor digiti minimi (ADM) and abductor pollicis brevis (APB) by magnetic stimulation of human brain and peripheral nervous. Results show that the latency of left and right Cz-APB is 25.23 ms and 25.19 ms respectively. The difference of the bilateral latencies is 2.24 ms. The rate of amplitude, the rate of area for bilateral sides is 0.45 and 0.37. The left and right central conduction time (CCT) of Cz-APB is 11.79 ms and 11.75 ms. The bilateral difference is 2.00 ms. The latency of left and right Cz-ADM is 25.23 ms and 25.19 ms respectively. The difference of bilateral latencies is 2.24 ms. The rate of amplitude, the rate of area for bilateral sides is 0.45 and 0.37. The left and right CCT of Cz-ADM is 11.79 ms and 11.75 ms. The bilateral difference is 1.86 ms.

Action Potentials↗
PubMed2000

[Study on chemical constituents of essential oil of Biota orientalis by GC-MS].

The essential oil was extracted from Biota orientalis (L) Endl by using steam distillery, analyzed with SE-54(30 m x 0.25 mm I.d) fused silica capillary column. The optimum separate and analytical conditions were researched. The amount of the components from the essential oil was determinated by monoliration method. The separated components were identified by GC-MS. There are 33 components which are make up 80% of the total essential oil were separated and identified.

Alkenes↗
PubMed2000

[Interactions between domains within the NH2- and COOH-terminal fragments of presenilins].

OBJECTIVE: To analyze the interactions between domains within the NH2- and COOH-terminal regions of presenilins. METHODS: The various constructions corresponding to NH2-terminal fragment (NTF) and COOH-terminal fragment (CTF) derivatives of presenilin 1 (PS1) and presenilin 2 (PS2) were generated by RT-PCR, and their interactions were assayed by yeast two-hybrid system. RESULTS: Domains within the NH- and COOH-terminal fragments of presenilins could directly interact with each other, and therefore form high molecular weight complex. The interaction site between domains within PS1 located at amino acid 361-447 of PS1 CTF, without the involvement of other partners. Similar interaction was not observed between PS11-360 and PS2341-448, PS2(1)-340 and PS1(361)-467. CONCLUSIONS: Intramolecular interaction between domains within the NH2- and COOH-terminal regions of presenilins may be critical to the folding and assembly of mature PS molecules.

Binding Sites↗
PubMed2000

[Chromatin structure and gene activation].

Nucleosome is the basic unit of chromatin. Nucleosome repression on gene transcription is a dominant factor in the tissue or cell type specific expression on a gene from the whole genome of an eukaryote. Derepression of chromatin to an open conformation may lead to the promotion of gene transcription. The nature of chromatin remodeling, the role of histone acetyltransferase and deacetylase, the repression mechanisms of chromatin induced by the methylated CpG binding proteins are discussed in this paper. The role of chromatin in the pathogenesis of diseases has attracted broad interests from the clinicians. Cis-elements of chromatin DNA helps defining the functional segments within the genome, which provide indispensable evidences to bio-informatics, and to the linkage between genomics and proteomics. Additionally, in vitro assembly of chromatin from multiple bio-active molecules to display new functions on gene activity indicates the growing importance of integrating studies in life sciences in the coming century.

Acetyltransferases↗
PubMed2000

[Alternative splicing of de novo methyltransferase gene 3b in adult and newborn mice].

OBJECTIVE: To unravel the biological significance of the alternative splicing of de novo methyltransferase 3b, expression of the Dnmt3b gene in various tissues and developmental stages was investigated in postnatal mice. METHODS: RT-PCR and capillary electrophoresis were employed to analyze the alternative splicing pattern of Dnmt3b in tissues of newborn and adult mice. The results had been further reaffirmed by repeating and statistics analysis. Bioinformatics tools were used to predict the structure and hydrophobicity of the Dnmt3b exon10 coding sequence. RESULTS: Isoform with Dnmt3b exon10 was the abundant form in lung of newborn mice and in liver of both newborn and adult mice, while in other tissues of newborn and adult mice, the spliced isoform was presented as the predominant one. Peptide encoded by Dnmt3b exon10 was mainly random coil on the surface of Dnmt3b protein. CONCLUSIONS: The data demonstrate that the specific expression of Dnmt3b exists in tissues and developmental stages of postnatal mice. The alternative splicing of the exon 10 of Dnmt3b is possibly involved in the regulation of Dnmt3b's catalytic function. These results provide an insight into the developmental regulation and physiological function of the alternative splicing of the Dnmt3b gene.

Alternative Splicing↗