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Biomedical subjects

W Sun

Publications and source records attributed to W Sun.

At least 181 records · Page 10Linked to original sources
PubMed1998

[Decrease of calcitonin gene-related peptide release from mesenteric arterial bed in diabetic rats and effect of nitric oxide].

Our previous work has shown that endotoxin triggers the release of calcitonin gene-related peptide (CGRP) from the mesenteric arterial bed, which is partially mediated by nitric oxide. In the present study, the changes of endotoxin-induced CGRP release from the isolated mesenteric arterial bed and the CGRP mRNA levels in dorsal root ganglia (DRG) of diabetic rats were studied in relation to the effect of nitric oxide. CGRP level in perfusate and the steady-state level of mRNA for CGRP in DRG were determined by RIA and semi-quantitatively by RT-PCR. The results showed that endotoxin (1-25 micrograms/ml) accumulated in perfusate caused concentration-dependent release of CGRP, which was significantly decreased in mesenteric arterial bed of diabetic rats. As compared with age-related control, the endotoxin (10 and 25 micrograms/ml) -induced CGRP release in diabetic rats was attenuated by 27% and 40%, respectively. L-NAME, an inhibitor of nitric oxide synthase, inhibited the effect of endotoxin in dose of 10 and 25 micrograms/ml by 23% and 46%, respectively against the control rats. However, there was no inhibitory effect of L-NAME on endotoxin-induced CGRP release in diabetic rats. The CGRP mRNA level in DRG showed no significant difference between the two groups. These results indicate that the response of the isolated mesenteric arterial bed to endotoxin-induced CGRP release in diabetic rats is significantly lower than that in control. The mechanism, at least in part, is due to a decrease of nitric oxide mediated release of CGRP, rather than a decrease of CGRP gene expression.

Animals↗
PubMed1998

[Modulatory action of alpha 2-adrenoceptor on calcitonin gene-related peptide release from rat mesenteric arterial bed].

The release of calcitonin gene-related peptide (CGRP) from peripheral terminals of sensory nerves was modulated via multiple mechanisms. In the present study, pharmacological agents were used to investigate the modulatory action of alpha 2-adrenoceptor on endotoxin-induced CGRP release from isolated perfused rat mesenteric arterial bed. The results showed that UK14304 (3 x 10(-6) mol/L), a potent alpha 2-adrenoceptor agonist, significantly inhibited both basal and endotoxin-induced CGRP release by 22%-42%, while specific antagonist of alpha 2-adrenoceptor yohimbine (10(-5) mol/L) blocked the effect of UK14304 completely. The data suggest that presynaptic alpha 2-adrenoceptor has an inhibitory effect on basal and endotoxin-induced CGRP release. Dysfunction of alpha 2-adrenoceptor in the late stage of endotoxic shock may be involved in the excess release of CGRP from the peripheral nerves.

Adrenergic alpha-Agonists↗
PubMed1998

[In vitro analysis of cross immunoreaction between CGRP and endotoxin in CGRP radioimmunoassay].

In the present study, the effect of endotoxin on the radioimmunoassay of calcitonin gene-related peptide (CGRP) was investigated by method of radioimmunoassay. The results showed a competitive combination of endotoxin at high-concentrations (higher than 5 micrograms/ml) with multiclonal antibody of CGRP, and the cross immunoreaction ratio between CGRP and endotoxin was 5.6 x 10(-6). The mixed endotoxin in samples was effectively cleared through C18 column purification. The data indicated that endotoxin interfered CGRP radioimmunoassay in vitro at high concentrations. The influence of endotoxin on CGRP radioimmunoassay can be avoided through C18 column purification for the endotoxin-containing samples.

Animals↗
PubMed1998

[Abnormal augmentation of the evoked potential and morphological changes of guinea pig cochlea induced by cisplatin].

OBJECTIVE: To investigate the characteristic of cochlear microphone(CM), summating potential(SP), compound action potential(CAP) and the morphological changes of hair cells after selective damage to the inner ear by acute cochlear perfusion of cisplatin. METHODS: Dynamic changes of CM, -SP and CAP were recorded by glass electrode from the third turn of the scala media guinea pig's cochlea before and during cisplatin perfusion of the whole cochlea for 2 hours. RESULTS: It indicated that after one hour of the perfusion, the amplitude of CM, -SP and CAP decreased at stimulation intensity < or = 60 dB SPL, while the amplitude increased at stimulation intensity > or = 70 dB SPL, as compared with those before perfusion (the average of CM increased by 3.6 mV at 90 dB SPL, average of -SP increased by 1.6 mV at 120 dB SPL, average of CAP increased by 0.23 mV at 90 dB SPL). After two hours of perfusion, the amplitude of CM, -SP and CAP decreased in all the stimulation intensity. The succinic dehydrgenase (SDH) staining was decreased in OHCs, while that of IHC's remained normal. Transmission electron microscopic examination of organ of Corti showed morphological changes in OHCs, such as disappearance of nuclear chromosome, denature and reduction number, mitochondria while the structure of IHCs remained normal. CONCLUSION: The abnormal augmentation phenomenon of CM and -SP may be due to the abnormal modulation of Ca2+ in IHCs and OHCs. The abnormal augmentation of CAP suggests that the suppression effects of OHCs and efferent neurotransmitter on IHCs and afferent neurotransmitter may be reduced after OHCs damage.

Action Potentials↗
PubMed1998

[Distal spleno-caval shunt in 66 patients with portal hypertension].

OBJECTIVE: To evaluate the long-term results and operative experience of distal splenocaval shunt. METHOD: 66 patients with portal hypertension were treated by distal spleno-caval shunt. Of these patients 57 were males and 9 females with a mean age of 39 years. All the patients were followed up. RESULT: The operative mortality rate was 7.58%. Only 5 patients experienced recurrent bleeding (7.58%). None of the patients had clinical hepatic encephalopathy. Five-year survival rate was 70.45%. CONCLUSION: Distal splenocaval shunt is suitable for portal hypertension patients with hepatopetal portal flow.

Adult↗
PubMed1998

[Expression of nm23 in gastrointestinal smooth muscle tumors and its relation to cell proliferative activity].

OBJECTIVE: To determine the relationship between nm23 expression and benign or malignant degree, metastasis, prognosis and cell proliferative activity of gastrointestinal smooth muscle tumors (GISMT). METHOD: 86 cases of GISMT were studied, and nm23 was detected by the immunohistochemical staining S-P method. The cell proliferative activity was evaluated by the silver colloid method for argyrophilic nucleolar organizer regions proteins (AgNORs) and by the immunohistochemical staining S-P method for proliferating cell nuclear antigen (PCNA). RESULT: The expression of nm23 declined significantly according to the following order: leiomyomas, low malignant leiomyosarcomas, high malignant leiomyosarcomas (P < 0.01). The expression of nm23 was associated with the tumors with or without contiguous organ invasion or distant metastasis, the size of tumors, the tumors with or without center necrosis (P < 0.01 or P < 0.05). The five-year survival rate was significantly higher in patients with nm23 positive expression than that with nm23 negative expression (P < 0.05). The expression of AgNORs and PCNA with nm23 negative cases was obviously higher than that with nm23 positive cases (P < 0.01). CONCLUSION: nm23 is a valuable indicator for the biological characteristics of GISMT. nm23 expression and cell proliferative activity can supply a deficiency each other in distinguishing malignant from benign tumors, judging the malignant degree, and predicting the prognosis of the patients with GISMT.

Adolescent↗
PubMed1998

[Synthesis and evaluation of restricted access stationary phases].

The restricted access stationary phase (RAS) are a new type of chromatographic packing material having a hydrophobic interior covered with a hydrophilic barrier. The RAS is used for direct injection in high-performance liquid chromatography for determination of drugs in biological fluids. These stationary phases include internal surface reverse phase, semipermeable surface, shielded hydrophobic phase and mixed functional phase (MFP). A kind of MFP packing material was synthesized from a porous silica gel-introduction of hydrophobic phenyl phase and introduction of hydrophilic diol phase. The MFP of RAS, on which proteins were eluted in the void volume, while the drugs were retained and separated, can be used for direct injection analysis of hydrophilic and hydrophobic drugs in serum and plasma. The recovery of the drugs in human serum was almost 100% with good reproducibility.

Blood Proteins↗
PubMed1998

[Sequencing and homology analysis of cDNAs encoding FhGST and AsGST].

AIM: To study the homologies between FhGST, AsGST and Sj26GST. METHODS: Total RNAs were extracted from Fasciola hepatica (Fh) and Ascaris suum (As) by guanidine hydrochloride/CsCl ultra-centrifugation. Two pairs of primers were designed according to FhGST and AsGST sequences. RT-PCR was carried out using total RNA as template. PCR products were directly sequenced. Then the homology analysis was made using DNASIS software on nucleotide level. RESULTS: A FhGST403 bp fragment and a AsGST411 bp fragment were obtained and they both located in the open reading frame. CONCLUSION: On nucleotide level, the homologies are 59% and 54% between the two cloned fragments and Schistosoma japonicum 26 kDa GST (Sj26GST) respectively.

Animals↗
PubMed1998

[Purification and identification of the bovine rotavirus receptor on MA104 cells].

In this research the bovine rotavirus(BRV) receptor on MA104 cells was purified and identified. The monoclonal antibody(McAb) against BRV receptor was coupled with the CNBr-activited sepharose 4B. BRV receptor was purified from the MA104 cell extracts by the method of the immunoaffinity chromatography. The results of the indirect ELISA ard the dot immunobinding assay showed that the BRV receptor antigenicity of the purified compound was positive. On SDS-polyacrylamide gel electrophoresis (SDS-PAGE) the eluate from the column with the McAb coupled showed a single band, corresponding to the elution peak. The eluate from the column without antibody showed no such a band on SDS-PAGE. The result of Western blot showed the purified compound could be distinguished by the McAb against BRV receptor. Solid-phase assay showed the purified compound had the ability to bind BRV. The mouse immunoserum against the purified compound could block the BRV infection to its host cells. The experimental results above showed that the purified compound was the receptor for BRV.

Animals↗
PubMed1998

[Collagen sponge and its hemostatic properties].

Soluble collagen was extracted from bovine tendon in acid solution. Collagen sponge hemostatics were prepared by means of lyophibization. The amino acid and UV spectrum analyses were made to confirm the composition of the soluble collagen. The results of experiments on rabbits indicated the collagen sponge prepared in the authors' lab had excellent hemostatic and adhesive properties in vivo surgical tests.

Amino Acids↗
PubMed1998

[Hyaluronic acid and laminin in patients with ischemic necrosis of femoral head].

To study the course and clinical significance of hyaluronic acid (HA) and laminin(LN), the main components of extracellular matrix in ischemic necrosis of femoral head(INFH), the quantities of HA and LN were measured by radioimmunoassay in 45 patients suffering from INFH with different pathogenesis, and in 30 normal subjects(NS). The results showed that the level of HA in patients with INFH was markedly higher than that of NS group(t = 3.29, P < 0.01). The patients with hormone type INFH had the highest level of HA(t = 3.62, P < 0.01). The level of LN in patient with INFH was significantly higher than that of NS group(t = 2.84, P < 0.01). The increased levels of HA and LN were positively correlated with the development of the disease. These suggest that quantity analysis of HA and LN may be used as a good indicator in early diagnosis and prognosis of INFH.

Adolescent↗
PubMed1998

[A new approach to correction method for matrix effect in X-ray fluorescence spectroscopy analysis].

With the help of fundamental parameter program developed by the authors, the matrix effect of multicomponent complex sample and the composition of each element's X-ray fluorescence intensity are calculated. A new mathematical model for correcting multicomponent matrix effect is deduced theoretically. This model provides a new method to calculate influence coefficients alpha and beta. The correction model and the influence coefficients introduced by this paper have clear and definite physical meaning, which give satisfactory result when utilized in analyzing stainless steel sample. The paper also indicates that the effect of tertiary fluorescence can not be neglected in some cases. From the result of comparison experiments, we draw a conclusion that the tertiary fluorescence effect must be considered while analyzing Cr in a steel sample with high concentration of Ni.

English Abstract↗
PubMed1998

Involvement of tyrosine phosphorylation of p185(c-erbB2/neu) in tumorigenicity induced by X-rays and the neu oncogene in human breast epithelial cells.

Ionizing radiation is the exogenous agent best proven to induce breast cancer. c-erbB2/neu amplification and overexpression are known to occur in breast cancer and are correlated with aggressive tumor growth and poor prognosis. We have developed simian virus 40-immortalized cell lines from normal human breast epithelial cells (HBECs) with luminal and stem-cell characteristics. In this study, we examined whether x-rays and a mutated neu oncogene are capable of inducing tumorigenicity in these cells. The results indicated that x-rays were effective in converting immortal non-tumorigenic HBECs to weakly tumorigenic cells that then could be transformed to highly tumorigenic cells by the neu oncogene. The in vitro growth of these tumorigenic cells was significantly faster than that of the parental non-tumorigenic cells in growth factor- and hormone-supplemented or -depleted media. The neu oncogene, however, had no tumorigenic effect on immortal non-tumorigenic cells. The expression of p185(c-erb82/neu) was elevated in neu-transduced immortal or weakly tumorigenic cell lines. However, only in the latter was p185(c-erbB2/neu) found to be phosphorylated at tyrosine residues. Thus, x-rays appear to induce a genetic alteration that confers weak tumorigenicity on immortal HBECs and interacts with p185(c-erbB2/neu) directly or indirectly to give rise to fast-growing tumors.

Animals↗
PubMed1997

Immunization against the agent of human granulocytic ehrlichiosis in a murine model.

The agent of human granulocytic ehrlichiosis (HGE) is a newly recognized tick-borne pathogen that resides within polymorphonuclear leukocytes. C3H/HeN mice can become infected with the agent of HGE (designated aoHGE) by syringe inoculation or tick-borne infection and develop transient neutropenia. They thereby partially mimic human disease and provide a model in which to study immunity to this microorganism. Mice vaccinated with lysates of purified aoHGE, or administered aoHGE antisera, were partially protected from both syringe- and tick-transmitted challenge with aoHGE. These data suggest that antibodies are sufficient to provide substantial, but not complete, immunity against aoHGE.

Animals↗
PubMed1997

A mutation in the aryl hydrocarbon receptor (AHR) in a cultured mammalian cell line identifies a novel region of AHR that affects DNA binding.

Introduction of a retroviral expression vector for the aryl hydrocarbon receptor (AHR) restores CYP1A1 inducibility to a mutant derivative of the Hepa-1 cell line that is defective in induction of CYP1A1 by ligands for the receptor. An AHR protein with normal ligand binding activity is expressed in the mutant but ligand treatment of mutant cell extract fails to induce binding of the AHR. ARNT (aryl hydrocarbon receptor nuclear translocator) dimer to the xenobiotic responsive element (XRE). AHR cDNAs derived from the mutant encode a protein that is unimpaired in ligand-dependent dimerization with ARNT, but the AHR.ARNT dimer so formed is severely impaired in XRE binding activity. The mutant cDNAs contain a C to G mutation at base 648, causing a cysteine to tryptophan alteration at amino acid 216, located between the PER-ARNT-SIM homology region (PAS) A and PAS B repeats. Introduction of the same mutation in the wild-type AHR sequence by site-directed mutagenesis similarity impaired XRE binding activity. Substitution with the conservative amino acid, serine, had no effect on XRE binding. The tryptophan mutation, but not the wild-type allele, was detectable in genomic DNA of the mutant. The implication that an amino acid within the PAS region may be involved in DNA binding indicates that the DNA binding behavior of AHR may be more anomalous than previously suspected.

Alleles↗
PubMed1997

Impaired motor coordination and persistent multiple climbing fiber innervation of cerebellar Purkinje cells in mice lacking Galphaq.

Mice lacking the alpha-subunit of the heterotrimeric guanine nucleotide binding protein Gq (Galphaq) are viable but suffer from ataxia with typical signs of motor discoordination. The anatomy of the cerebellum is not overtly disturbed, and excitatory synaptic transmission from parallel fibers to cerebellar Purkinje cells (PCs) and from climbing fibers (CFs) to PCs is functional. However, about 40% of adult Galphaq mutant PCs remain multiply innervated by CFs because of a defect in regression of supernumerary CFs in the third postnatal week. Evidence is provided suggesting that Galphaq is part of a signaling pathway that is involved in the elimination of multiple CF innervation during this period.

Age Factors↗
PubMed1997

Suppression of GnRH gene expression in GT1-1 hypothalamic neuronal cells: action of protein kinase C.

We attempted to elucidate molecular mechanisms of gonadotropin-releasing hormone (GnRH) gene regulation by the protein kinase C (PKC) pathway in GT1-1 cells. Activation of PKC with 12-tetra-decanoylphorbol-13-acetate (TPA) or inhibition with staurosporine or calphostin C down-regulated GnRH mRNA levels. A serial deletion mutant analysis revealed that this suppression was mediated by the proximal region (-187/-69) of the mouse GnRH promoter. TPA transiently induced c-fos mRNA, whereas staurosporine or calphostin C failed to do so. However, PKC inhibitors blocked the TPA-evoked c-fos induction. Over-expression of PKC alpha down-regulated GnRH promoter activity, indicating that PKC activation was sufficient to inhibit GnRH gene expression. These results suggest that both activation and inhibition of PKC decrease the GnRH gene expression in the GT1-1 cells probably through different signal cascade mechanisms.

Animals↗