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Biomedical subjects

W Shen

Publications and source records attributed to W Shen.

At least 127 records · Page 7Linked to original sources
PubMed1999

[Lymphoscintigraphy: evaluating lymphatic spread of rectal cancer].

OBJECTIVE: To investigate lymphatic drainage of rectal and lymphatic spread of rectal cancer. METHODS: Rectal endoscopic lymphoscintigraphy was performed in 37 volunteers and 16 patients. One millilitre dextran marked with (99m)Tc was injected bilaterally into submucosa of the rectum through rectal endoscopy. 1, 2, 3 hours after the injection, rectal lymphoscintigraphy was registered with a computerized gamma camera (TOSHIBA GCA901A). RESULTS: Lymphoscintigraphy in control subjects showed upward epirectal and pararectal nodes. The average number of the nodes was 12 three hours after the injection. Compared with histological node examination in all patients operated upon for rectal cancer, rectal endoscopic lymphoscintigraphy showed a sensitivity of 97.1%, a specificity of 75.0%, an overall accuracy of 87.5%, a false positivity of 25.0%, and false negativity of 8.3%. CONCLUSION: The method is better for evaluating lymphatic spread of rectal cancer before operation.

Adult↗
PubMed1999

[A study on digestion of Gal alpha (1,3) Gal on porcine vascular endothelial cells by alpha-galactosidase].

This study was designed to explore ways to prevent immune rejection in xenotransplantation. Porcine vein endothelial cells treated by alpha-Galactosidase were used to investigate the expression of Gal alpha(1,3) Gal on porcine vascular endothelial cells, and the morphology of vascular endothelial cells. The results showed that Gal alpha (1,3) Gal (alpha-Gal) on porcine vascular endothelial cells, which is the major epitome of xenoantigen, could be digested by alpha-Galactosidase within 30 minutes. No morphological changes were observed in the porcine vascular endothelial cells within a period of one hour after the treatment. This suggested that the treatment of porcine tissues with alpha-Galactosidase could be a new and effective way to prevent hyperacute rejection after xenotransplantation.

Animals↗
PubMed1999

[Expression of Schistosoma japonicun fatty acid binding protein gene in silkworm cells and larvae].

AIM: To express the fatty acid binding protein (Sj14FABP) gene of Schistosoma japonicun in the silkworm cells and larvae. METHODS: A 600 bp DNA fragment containing Sj14FABP gene was cloned into baculovirus transfer vector of pBacPAK His1 to construct recombinant transfer vector Sj14-pBac PAK His1. Coinfection was accomplished with this vector and Bombyx mori nuclear polyhedrosis virus (BmNPV) DNA in BmN cells. The recombinant virus of Bm-Sj14 was screened using dot-blotting. The BmN cells and silkworm larvae were infected with Bm-Sj14 to express Sj14FABF gene. Western blotting and ELISA were used to identify the antigenicity of the recombinant protein. RESULTS: Sj14FABP gene was successfully expressed in the BmN cells and silkworm larvae infected with Bm-Sj14. The product was a 18 kDa fusion protein. The yield in BmN cells was about 100 micrograms/1 x 10(6) cells and 33 micrograms/ml cell supernatant. In silkworm larvae, the product yield was 4 mg/ml haemolymph as well as 4.6 mg/g silkworm tissue. The recombinant protein could be recognized by Western blotting and ELISA using the sera from mice immunized with SWAP. CONCLUSION: Sj14FABP gene has been successfully expressed in BmNPV system and the product has high antigenicity.

Animals↗
PubMed1999

[Supracricoid partial laryngectomy for laryngeal cancer].

OBJECTIVE: To analyze the key points, especially the indications and contraindications of supracricoid partial laryngectomy (SCPL). METHODS: During the years 1995 to 1996, 18 patients with laryngeal cancer underwent supracricoid partial laryngectomy. Ten of them (55.56%) were classified as T1b and T2 glottic cancers, 8 of them (44.44%) as T3 and T4 glottic cancer or transglottic carcinomas. Three types of supracircoid partial laryngectomy (CHP, CHEP and TCHEP) were employed accordingly. RESULTS: Overall three-year survival rate was 94.40%. All patients were decannulated from 14 to 42 days and all resumed normal oral feeding from 14 to 30 days. Speech was good in all patients. CONCLUSION: The SCPL procedure not only increases local control rate, but also maintains physiologic speech and swallowing.

Adult↗
PubMed1999

Expression of ICAM-1 and LFA-1 molecules in relation to renal allograft rejection in rats.

OBJECTIVE: The purpose of this study was to assess the renal graft expression of ICAM-1 (intercellular adhesion molecule-1) and LFA-1 (lymphocyte function-associated antigen-1) molecule with relation to graft rejection. METHODS: Rat kidney transplantation was performed according to the procedure of Kamada with some modification. Experimental rats were divided into 5 groups. The survival time of recipient rats and function of grafts after renal transplantation were observed. The sections of renal graft were stained for monoclonal antibody ICAM-1 and LFA-1, and then quantification of ICAM-1 and LFA-1 expression was accomplished by computer image analysis. RESULTS: ICAM-1 and LFA-1 increased significantly in the renal allograft rejection group as compared with the non-rejection groups (P<0.05). CONCLUSION: Both biopsy of renal graft and monitoring of ICAM-1 and LFA-1 are useful tools in diagnosing and treating acute rejection.

Animals↗
PubMed1998

Effect of nitrous oxide on excitatory and inhibitory synaptic transmission in hippocampal cultures.

Nitrous oxide (N2O; laughing gas) has been a widely used anesthetic/analgesic since the 19th century, although its cellular mechanism of action is not understood. Here we characterize the effects of N2O on excitatory and inhibitory synaptic transmission in microcultures of rat hippocampal neurons, a preparation in which anesthetic effects on monosynaptic communication can be examined in a setting free of polysynaptic network variables. Eighty percent N2O occludes peak NMDA receptor-mediated (NMDAR) excitatory autaptic currents (EACs) with no effect on the NMDAR EAC decay time course. N2O also mildly depresses AMPA receptor-mediated (AMPAR) EACs. We find that N2O inhibits both NMDA and non-NMDA receptor-mediated responses to exogenous agonist. The postsynaptic blockade of NMDA receptors exhibits slight apparent voltage dependence, whereas the blockade of AMPA receptors is not voltage dependent. Although the degree of ketamine and Mg2+ blockade of NMDA-induced responses is dependent on permeant ion concentration, the degree of N2O blockade is not. We also observe a slight and variable prolongation of GABAA receptor-mediated (GABAR) postsynaptic currents likely caused by previously reported effects of N2O on GABAA receptors. Despite the effects of N2O on both NMDA and non-NMDA ionotropic receptors, glial glutamate transporter currents and metabotropic glutamate receptor-mediated synaptic depression are not affected. Paired-pulse depression, the frequency of spontaneous miniature excitatory synaptic currents, and high-voltage-activated calcium currents are not affected by N2O. Our results suggest that the effects of N2O on synaptic transmission are confined to postsynaptic targets.

Animals↗
PubMed1998

Metabotropic and ionotropic glutamate receptors regulate calcium channel currents in salamander retinal ganglion cells.

1. Glutamate suppressed high-voltage-activated barium currents (IBa, HVA) in tiger salamander retinal ganglion cells. Both ionotropic (iGluR) and metabotropic (mGluR) receptors contributed to this calcium channel inhibition. 2. Trans-ACPD (1-aminocyclopentane-trans-1S,3R-dicarboxylic acid), a broad-spectrum metabotropic glutamate receptor agonist, suppressed a dihydropyridine-sensitive barium current. Kainate, an ionotropic glutamate receptor agonist, reduced an omega-conotoxin GVIA-sensitive current. 3. The relative effectiveness of selective agonists indicated that the predominant metabotropic receptor was the L-2-amino-4-phosphonobutyrate (L-AP4)-sensitive, group III receptor. This receptor reversed the action of forskolin, but this was not responsible for calcium channel suppression. l-AP4 raised internal calcium concentration. Antagonists of phospholipase C, inositol trisphosphate (IP3) receptors and ryanodine receptors inhibited the action of metabotropic agonists, indicating that group III receptor transduction was linked to this pathway. 4. The action of kainate was partially suppressed by BAPTA, by calmodulin antagonists and by blockers of calmodulin-dependent phosphatase. Suppression by kainate of the calcium channel current was more rapid when calcium was the charge carrier, instead of barium. The results indicate that calcium influx through kainate-sensitive glutamate receptors can activate calmodulin, which stimulates phosphatases that may directly suppress voltage-sensitive calcium channels. 5. Thus, ionotropic and metabotropic glutamate receptors inhibit distinct calcium channels. They could act synergistically, since both increase internal calcium. These pathways provide negative feedback that can reduce calcium influx when ganglion cells are depolarized.

Ambystoma↗
PubMed1998

Amino acid residues in Std1 protein required for induction of SUC2 transcription are also required for suppression of TBPDelta57 growth defect in Saccharomyces cerevisiae.

The STD1 gene of Saccharomyces cerevisiae was isolated independently as a multicopy suppressor of a dominant negative mutation in the TATA-binding protein and of a mutation in the Snf1/Snf4 kinase complex, suggesting that Std1 might couple the Snf1 kinase signaling pathway to the transcriptional machinery. In order to identify the protein domains that specify these activities of the Std1 protein, a plasmid library of randomly mutagenized STD1 genes was screened for loss of function alleles using complementation of the raffinose growth defect of a std1-, mth1- strain as an assay. One missense allele (P236S) with complete loss of function at 30 degreesC and four missense alleles (L173F, E225K, S269L and E274K) that conferred a temperature sensitive phenotype were identified. The C-terminal 20 residues of Std1 were essential for SUC2 derepression, whereas the deletion of the N-terminal 96 residues did not affect SUC2 gene induction. Std1 mutants that lost the ability to induce SUC2, were also unable to suppress the growth defect caused by the expression of the dominant negative TBPDelta57 protein, suggesting that these two genetic screens may be detecting the same biological activity.

Alleles↗
PubMed1998

Biodegradation in vitro and retention in the rabbit eye of crosslinked poly(1-vinyl-2-pyrrolidinone) hydrogel as a vitreous substitute.

To elucidate the relatively short retention of crosslinked poly(1-vinyl-2-pyrrolidinone) hydrogels in the eye when used as potential vitreous substitutes, a 14C-labeled hydrogel was produced and subjected to both in vitro biodegradation assays and in vivo experiments. The polymer was synthesized by the free-radical copolymerization of 99% 1-vinyl-2-pyrrolidinone with 1% 14C-methyl methacrylate in the presence of ethylene glycol dimethacrylate (0.1%) as crosslinking agent. The in vitro protocol for assessing the biodegradation included the incubation of hydrogel with hydrolases (trypsin or collagenase), followed by examination of changes in its physical characteristics and by monitoring its residual radioactivity, as well as by detection of possible degradation products. Within the maximum duration of experiments (4 weeks), none of the procedures indicated biodegradation of polymer. The hydrogel was also injected into the vitreous humor of rabbits and followed up to 4 weeks. Residual radioactivity measurements of the vitreous contents indicated that 50% of the polymer was removed by the end of this period. Histopathologic examination revealed cell infiltrates of the mononuclear phagocyte system in both vitreous and retinal tissue. A possible phagocyte-mediated mechanism for the dissipation of hydrogel is discussed.

Animals↗
PubMed1998

Preface.

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Journal Article↗
PubMed1998

Production and testing of Schistosoma japonicum candidate vaccine antigens in the natural ovine host.

The objectives of this work were to clone and express Chinese strain Schistosoma japonicum antigens and evaluate their immunogenicity and protective efficacy in the natural ovine host in China. Recombinant antigens selected for testing were: isoforms of glutathione S-transferase Sj28GST and Sj26GST; the large hydrophilic domain of Sj23, the homologue of the protective S. mansoni membrane antigen Sm23; and a 3' fragment of S. japonicum paramyosin. In addition, Chinese strain S. japonicum native paramyosin and GST were purified and used for vaccination. Antigens were co-administered with Freund's adjuvants or BCG. We also examined the effects of co-administration of native unfractionated GSTs with keyhole limpet haemocyanin (KLH), which shares a cross-reactive protective epitope with schistosomes. These are the first side-by-side comparisons of candidate defined-antigen schistosomiasis vaccines in a natural host. Significant partial protection was obtained with each of the antigens tested. Less protection was obtained with a recombinant fragment of S. japonicum paramyosin compared with native paramyosin. Co-administration of native GST and KLH was no more effective than vaccination with either antigen alone. Although encouraging levels of protection against S. japonicum were demonstrated using each of these antigens, further work is needed to optimise vaccine delivery and vaccination schedules.

Adjuvants, Immunologic↗
PubMed1998

Lack of desensitization and enhanced efficiency of calcium channel promoter in conscious dogs with heart failure.

The goal of this study was to compare responses to a calcium promoter, BAY y 5959, and dobutamine (Dob) in heart failure (HF). Dogs (n = 9) were chronically instrumented and studied in the conscious state before and after pacing-induced HF. In the control state, BAY y 5959 (20 microgram. kg-1. min-1) increased the first derivative of left ventricular (LV) pressure (dP/dt) by 83 +/- 8% and mean arterial pressure (MAP) by 8 +/- 2% and decreased heart rate (HR) by 30 +/- 3%. With Dob (10 microgram. kg-1. min-1) LV dP/dt rose similarly (+80 +/- 6%), but HR also rose (+25 +/- 4%) (P < 0.05 vs. BAY y 5959). After HF developed, BAY y 5959 still increased LV dP/dt by 108 +/- 8% and MAP by 21 +/- 2% and decreased HR by 28 +/- 4%, whereas Dob increased LV dP/dt by only 50 +/- 7% (P < 0.05 vs. BAY y 5959) and MAP by 7 +/- 3%, and HR did not change (+3 +/- 3%) (P < 0.05 vs. BAY y 5959). In HF, cardiac work increased more (P < 0. 05) with BAY y 5959 (+105 +/- 13%) compared with Dob (+47 +/- 11%), yet myocardial oxygen consumption increased similarly with the two drugs. Accordingly, mechanical efficiency increased more (P < 0.05) with BAY y 5959 (+73 +/- 14%) than with Dob (+17 +/- 12%). These data indicate that 1) increases in contractility mediated directly by Ca2+ are relatively resistant to desensitization in HF; and 2) the calcium-channel promoter can produce increases in myocardial contractility and cardiac work similar to those of Dob at a significantly lower oxygen cost, thereby enhancing mechanical efficiency in HF.

Animals↗
PubMed1998

Cardiac protection by long-term treatment with captopril in patients with acute myocardial infarction.

OBJECTIVES: To assess the effects of long-term angiotensin-converting enzyme (ACE) inhibitor treatment with captopril on cardiac function in acute myocardial infarction (AMI). METHODS: One hundred and one patients with AMI who were admitted to hospital within 72 hours of the onset of symptoms with no cardiogenic shock were randomly allocated to captopril (n = 52; group I) and conventional treatment (n = 49; group II). Left ventricular (LV) systolic performance and diastolic transmitral flow velocity profiles were assessed by Doppler echocardiography at admission (1.2 +/- 1.1 days), before discharge (27 +/- 10 days) and during follow-up (363 +/- 31 days). RESULTS: At one year follow-up, in group I LV end-diastolic volume decreased, and ejection fraction increased due to a disproportionate decrease in end-systolic volume. The incidence of cardiac dilatation was reduced. LV early diastolic filling velocity (E) increased and late atrial filling velocity (A) decreased, resulting in an elevation of E/A ratio. However, the mean values of LV systolic and diastolic functional parameters were unchanged in group II. CONCLUSIONS: Long-term treatment with captopril exerts a beneficial effect on cardiac protection for patients with AMI.

Aged↗
PubMed1998

[The changes of maternal and umbilical serum nitric oxide in patients with pregnancy induced hypertension].

OBJECTIVE: To determine whether levels of maternal and umbilical serum nitric oxide (NO) were changed in patients with pregnancy induced hypertension (PIH). METHODS: 40 women with PIH, 40 normal late trimester pregnant women and 20 nonpregnant women were studied. Maternal venous blood were collected from all the cases and umbilical venous blood were collected from 28 of the first two groups respectively. Serum NO2-/NO3-, the endproducts of NO, were measured with the Griess reaction after reduction with nitrate reductase. RESULTS: The mean NO2-/NO3- in maternal venous serum were 23.30 +/- 5.60 mumol/L in nonpregnant group, 26.42 +/- 4.54 mumol/L in normal pregnant group and 32.58 +/- 5.06 mumol/L in PIH group. Umbilical serum NO2-/NO3- were 12.26 +/- 4.91 mumol/L in normotensive groups and 14.64 +/- 3.90 mumol/L in PIH group. Maternal serum NO2-/NO3- in nonpregnant group were lower than that both in normal pregnant group (P < 0.05) and in PIH group (P < 0.01). Compared with the normotensive group, maternal serum NO2-/NO3- in PIH group was significantly higher (P < 0.01), while significantly higher serum NO2-/NO3- were also found in umbilical venous blood in PIH group (P < 0.05). There were no correlations between serum NO2-/NO3- level and blood pressure or birth weight. The total nitrite levels in fetal circulation was lower than that in maternal circulation in both pregnant groups (P < 0.01). CONCLUSION: Total nitrites are increased both in maternal and fetal circulation in PIH. The result indicates that the increase of NO may be secondary compensative reaction in PIH.

Female↗
PubMed1998

[Clinical analysis of postoperative radiotherapy for stage I endometrial cancer].

OBJECTIVE: To evaluate the role and complications of adjuvant radiotherapy for stage I endometrial cancer after surgery. METHODS: From May, 1986 to December, 1995, 20 patients with stage I endometrial cancer received total abdominal hysterectomy with bilateral salpingo-oophorectomy(TAH/BSO), and additional pelvic lymph node dissection in 5 cases. Most of the patients received radio therapy in 2-4 weeks after surgery. The radiation fields included pelvic lymph nodes with a total dose of 40-50 Gy. RESULTS: All the patients had survived for 10 years. Only one patient developed distant metastases. Acute radiation reaction was observed in all patients. Late radiation-induced damage occured in six patients and was severe in two. CONCLUSION: Postoperative radiotherapy in the management of stage I endometrial cancer is beneficial for the controal of local recurrence but has relatively high frequency of late radiation injury.

Adenocarcinoma↗