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Biomedical subjects

G Wu

Publications and source records attributed to G Wu.

At least 505 records · Page 28Linked to original sources
PubMed1995

[TLC scanning determination of baicalin content in niuhuang qingxin pills].

Baicalin in the samples was extracted with ultrasonic wave, the extract was spotted on thin-layer plates of gel GF254 and developed with the mobile phase consisting of toluene-ethylacetate-formic acid (2:3:2.2). Determinations were carried out with Shimadzu CS-930 TLC scanner with lambda s = 280 nm and lambda R = 207 nm. The linear range was 0.46-4.6 micrograms/ml. The average recovery of baicalin from the samples was 98.35%, RSD = 2.82%.

Anti-Infective Agents↗
PubMed1995

[Influence of SmI lesion on acupuncture-induced analgesia in thalamic Pf neurons and effects of iontophoretic ACh on their nociceptive responses].

This study aimed to investigate the role of ACh in SmI emanating descending modulation of thalamic Pf neurons in acupuncture analgesia. Multi-micropipettes were used for both extracellularly recording responses of thalamic Pf neurons to noxious stimulation of the plantar area and drug application in rats. It was found that (1) lesion of SmI obviously attenuated the inhibitory effect of EA applied at "Zusanli" and "Huantiao" points on nociceptive responses in Pfneurons; (2) after lesion of SmI iontophoretic application of ACh markedly suppressed the nociceptive responses of Pf neurons, which was significantly different from the effect of iontophoretic NaCl (as the control) showing no influence on them; (3) the inhibition induced by iontophoretic ACh applied in the rats with lesion of SmI was similar to that produced by EA applied in those with SmI intact. It is indicated that EA can activate SmI to release ACh to exert descending modulation, in which ACh is involved in SmI originating descending regulation of Pf neruons in acupuncture analgesia.

Acetylcholine↗
PubMed1995

Induced and spontaneous neuritogenesis are associated with enhanced expression of ganglioside GM1 in the nuclear membrane.

Neuro-2a neuroblastoma cells can be stimulated to extend neurites with a number of agents, one of which, neuraminidase, induces terminal differentiation by a mechanism involving enhanced Ca2+ influx. Permeabilization of such differentiated cells with saponin and treatment with cholera toxin B subunit linked to horseradish peroxidase revealed intense staining of the nuclear membrane, indicating the presence of GM1 ganglioside. Unstimulated cells had barely detectable levels of nuclear GM1. Nuclei isolated by sucrose density gradient centrifugation similarly showed intense staining with fluorescently labeled cholera toxin B subunit, in contrast to nuclei from undifferentiated controls. Treatment with chloroform-methanol removed most of the fluorogenic material. Chemical analysis of such nuclei from neuraminidase-treated cells confirmed significant elevation of GM1 above control levels, along with virtual absence of markers for plasma membrane and Golgi apparatus. Cerebellar granule cells from neonatal rats revealed a similar phenomenon following spontaneous neurite outgrowth in culture.

Animals↗
PubMed1995

[Evaluation of the prognosis of critically ill surgical patients by APACHE II score system].

A prospective trial was conducted in 386 critically ill surgical patients, the APACHE II score was used to quantify the severity of illness and to judge the outcome. Admission APACHE II score of these patients averaged 15.6 +/- 5.4, the mortality rates rose from 1.9% to 100% when the APACHE II score increased from 0 to 38. The score was closely correlated with the subsequent risk of hospital death for these patients (r = 0.75 P < 0.001). Critically ill surgical patients would be well served by APACHE II for quality assurance or outcome.

APACHE↗
PubMed1995

[Detection of hypermethylation in affected males with fragile X syndrome by PCR assay].

PCR technique was applied to detect hypermethylation at BssH II recognition sites within CpG island of FMR-1 gene in normal, affected, and clinically suspected males with fragile X syndrome. Hypermethylation was found to occur in all 7 affected and 5 of 26 suspected, but none of 15 normal males. The results of PCR assay are in good coincidence with those of Southern blot and cytogenetic assays. This PCR assay will be a promising method in the diagnosis of fragile X syndrome in males with mental retardation.

Base Sequence↗
PubMed1995

[Inhalation of platelet-activating factor induced guinea pig airway hyperresponsiveness: role of eosinophils activation].

Exposure of guinea pigs to aerosols of 200 micrograms/ml platelet-activating factor 24 h later, airway hyperresponsiveness to histamine induced and number of eosinophils and hypodense eosinophils in bronchoalveolar lavage fluid (BALF) increased, comparing with the control group. The number of eosinophils in BALF was corelated with PC20 value in PAF-treated group (r = -0.62, P < 0.05). However, the percentage of hypodense eosinophil in BALF had closer relation to airway responsiveness (r = -0.84, P < 0.01). The content of peroxidase in hypodense eosinophils in BALF for guinea pigs treated by inhalation of PAF was lowered markedly than that in normodense eosinophil (P < 0.05). The result suggested that chemotaxis and activation of eosinophils by PAF might play an important role in airway hyperresponsiveness.

Animals↗
PubMed1995

A simple method for the transformation of Agrobacterium tumefaciens by foreign DNA.

A method for successful introduction of Ti plasmid vector ( > 10 kb) into Agrobacterium tumefaciens is described. Competent A.tumefaciens cells were prepared with 50 mmol/L CaC1(2) at room temperature and introduction was done on ice followed by a 28 degrees C heat pulse. The efficiency of transformation was 10(-4)-10(-5) transformants per total recipient population or 10(6) transformants per microgram DNA. The effects of growth phase of A. tumefaciens cells, concentration of CaC1(2) solution, temperature, liquid N2, heat pulse, recovery time, and storage time of competent cells at 4 degrees C or -20 degrees C (in 15% glycerin) on transformation were studied.

Agrobacterium tumefaciens↗
PubMed1995

Membrane formation on the surface of implanted posterior chamber intraocular lenses.

PURPOSE: To study the prevention and treatment of the membrane formation on the lens surface after extracapsular cataract extraction (ECCE) with posterior chamber intraocular lens (PCIOL) implantation. METHODS: We reviewed the records of 312 cataractous patients that had undergone ECCE with PCIOL implantation between 1989 and 1993. Postoperatively all patients were examined under slit-lamp microscopy. The membrane formation on the surface of PCIOL in pupilar area was divided into four grades. Two membranes of surgical removal were observed under a transmission electron microscopy. One PCIOL of surgical removal was observed under a scanning electron microscopy. RESULTS: Of 312 patients, 21 had the membrane formation on the surface of the PCIOL postoperatively. The incidence of the membrane formation was 6.7%. Comparisons with cases of senile cataract showed the incidence to be significantly the highest among: 1. patients who had traumatic cataract (P < 0.05); 2. patients with complicated cataract (P < 0.05). Intraoperatively residual lens cortex and rupture of posterior capsule, interval time between the first and second eye operations less than 1 month are the main factors of membrane formation. The ultrastructure in membrane and cytology on the lens surface showed that the membrane on the surface of PCIOLs is usually composed of a cellular protein film and cellular elements, including macrophages, fibroblast-like cells, epithelioid cells, giant cells, fibroblasts and collagen fibrils, etc. CONCLUSIONS: The cellular response on the surface of an implanted PCIOL is a chronic foreign-body inflammatory reaction and the membrane of the surface of implanted PCIOL is a reactive membrane of the foreign-body.

Eye↗
PubMed1995

[Detection of FMR-1 gene expression by RT-PCR].

Fragile X syndrome [FRA(X)] as the most common form of inherited mental retardation in man has an incidence of one per 1250 and is associated with a fragile site at Xq27.3. A gene was identified at the fragile X locus and was designated Fragile X Mental Retardation-1 (FMR-1). FRA(X) resulted from expansion of (CGG)n trinucleotide repeat in 5' untranslated region of the human FMR-1 gene, and was associated with abnormal methylation of a CpG island 250 bp proximal to this (CGG)n repeat. Males with typical FRA(X) showed repression of FMR-1 transcription and absence of FMR-1 protein, which was believed to contribute to the fragile X phenotype. FMR-1 mRNA extracted from leukocytes in normal and clinically suspected males were detected by RT-PCR. The methylation status and CGG expansion were also studied by PCR and Southern blot. Two of 10 clinically suspected males were found devoid of FMR-1 expression and accompanied with hypermethylation of the CpG island and CGG trinucleotide repeat expansion.

CpG Islands↗
PubMed1994

A hydrophobic inhibitor of the nicotinic acetylcholine receptor acts on the resting state.

3-(Trifluoromethyl)-3-(m-iodophenyl)diazirine (TID) has recently been found to be a noncompetitive inhibitor of the nicotinic acetylcholine receptor (nAcChoR) by both photolabeling and flux assays (White et al., 1991). However, these experiments were done when TID was in equilibrium with the nAcChoR, and thus only its interactions with the resting and the desensitized states of the nAcChoR were studied. In this work we characterized the interaction between TID and nAcChoR in the open and resting states using a flux assay. When TID and acetylcholine were simultaneously mixed with the nAcChoR in native Torpedo vesicles, TID did not inhibit agonist-induced 86Rb+ flux. However, following prolonged preincubation (4 min) of TID with nAcChoR, complete inhibition was observed with a half-inhibition constant of 0.4 microM TID and a Hill coefficient of 0.9. This suggested that TID might act either on the resting or the desensitized state in preference to the open state of the nAcChoR. Preincubation of nAcChoR with TID, followed by a 7 ms agonist-induced flux assay, showed that the flux response declined exponentially with preincubation time. Assuming a pseudo-first-order process, analysis revealed the rate constant for the onset of inhibition of nAcChoR in the resting state to be in the range of (1.2-3.4) x 10(6) M-1 s-1. To test if fast desensitization was enhanced by TID under these conditions, we used a fluorescent analog of acetylcholine. Stopped-flow fluorimetry showed that the fraction of nAcChoR in the predesensitized state did not increase during preincubation with TID.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1994

Lymphocyte predominance Hodgkin's disease: lineage and clonality determination using a single-cell assay.

Lymphocyte predominance Hodgkin's disease (LPHD) is a clinically indolent condition. Although there is evidence that the putative neoplastic cell in this disease, the "L&H" cell, is of B-cell lineage, there is conflicting data concerning the clonality of these cells. Our study was aimed at clarifying the issue of lineage and clonality of the L&H cells of LPHD using a single-cell assay. Four cases of LPHD were studied. To circumvent the difficulties of obtaining fresh tissue and to be able to study representative cases, a new method was developed to obtain single-cell suspensions of L&H cells from archival formalin-fixed paraffin-embedded tissue. Single L&H cells were identified by morphology and immunostaining for epithelial membrane antigen, isolated using a micropipette, and subjected to polymerase chain reaction (PCR) amplification of the complematarity determining region 3 (CDR3) of the Ig heavy chain (IgH) gene, which is B-cell clone-specific. The PCR products were size-fractionated by polyacrylamide gel electrophoresis and representative products were directly sequenced. Single T cells and small B cells were also isolated from the tissues and used as negative and positive controls, respectively. In all four cases of LPHD, the IgH CDR3 of single L&H cells could be amplified. Within each case, the IgH CDR3 of single L&H cells was found to be of different length or of different sequence. Therefore, our results provide strong evidence for the B-cell origin of the L&H cells and the polyclonal nature of LPHD.

Antigens, CD↗
PubMed1994

The actions of 5-HT1 agonists and antagonists on nociceptive processing in the rat spinal cord: results from behavioural and electrophysiological studies.

We have developed a technique which allows drugs to be microinjected intrathecally intrathecally in anaesthetised rats whilst single unit recordings are made from dorsal horn neurones. Using this technique together with recordings of tail flick latency (TFL) elicited from lightly anaesthetised rats we have found that the specific 5-HT1a agonist 8-OH DPAT (15, 150, 300 nmol) increases nociceptive responses recorded from single dorsal horn neurones and decreases TFL. The non-specific 5-HT1b agonist TFMPP (300 nmol) and the general 5-HT1 agonist 5-CT (0.3, 3.0, 30 nmol) both decreased nociceptive responses and has inconsistent effects on TFL. Intrathecally applied 5-HT (130, 260 nmol) generally reduced nociceptive neuronal responses and increased TFL. In a minority of experiments, however, 5-HT increased nociceptive responses and it is suggested that this effect is associated with activation of 5-HT1a receptors. Activity at 5-HT1b receptors has the effect of suppressing or reducing responsiveness. The increased responsiveness of dorsal horn neurones to noxious stimulation associated with activity at 5-HT1a receptors may be associated either with increases in receptive field size, promotion of spinal nocifensive reflexes or the facilitation of the rostral transmission to specific brainstem sites.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1994

Expression of transforming growth factor beta type II receptor leads to reduced malignancy in human breast cancer MCF-7 cells.

The role of transforming growth factor (TGF) beta type II receptor in reversing the malignant phenotype of human breast cancer MCF-7 cells was examined. MCF-7 cells were insensitive to TGF beta 1 and expressed undetectable levels of cell surface TGF beta type I receptor (RI) and type II receptor (RII) by cross-linking with 125I-TGF beta 1. Stable transfection of a RII expression vector yielded 3 transfectants with varying levels of exogenous RII mRNA and protein levels. Expression of RII also increased TGF beta 1 binding to RI in all 3 clones. Proliferation of RII-positive clones was inhibited by exogenous TGF beta 1 in a dose-dependent manner, whereas the control clones remained TGF beta-insensitive. The RII transfectants were growth arrested in monolayer culture at saturation densities which were 41-66% of that of the Neo controls. They also showed reduced clonogenicity in soft-agarose. Tumorigenicity in ovariectomized, estrogen-supplemented nude mice was delayed in transfectants with low RII levels. Transfectants expressing high levels of RII showed a large reduction in tumorigenicity as well as a longer delay in tumor formation. Tumor growth was associated with loss of exogenous RII expression in transfectants. The results indicate that when systems for TGF beta signal transduction are intact, reconstitution of the TGF beta receptor system can lead to reversion of malignancy in cells lacking RII.

Animals↗
PubMed1994

Ethanol enhances agonist-induced fast desensitization in nicotinic acetylcholine receptors.

The reversible decline of the nicotinic acetylcholine receptor's response to acetylcholine during prolonged exposure to acetylcholine is known as desensitization. Here, we studied ethanol's modulation of fast agonist-induced desensitization of the nicotinic acetylcholine receptor in postsynaptic membrane vesicles from Torpedo using a fast kinetic technique: pulsed quenched flow. Preincubation of the vesicles with various concentrations of acetylcholine at 4 degrees C for times ranging from 80 ms to 1.5 s caused fast desensitization, which was revealed as a decreased 86Rb+ influx when the vesicles were subsequently briefly exposed to a saturating concentration of acetylcholine in 86RbCl. Acetylcholine-induced fast desensitization had a maximum observed rate, kdmax, of 6.8 s-1, a half-effect concentration, KD, of 157 microM, and a Hill coefficient of 1.4. Increasing the ethanol concentration up to 1.0 M causes a linear increase in kdmax, such that 1.0 M ethanol doubles the rate. Ethanol (1 M) also decreased KD 10-fold without changing the Hill coefficient. We consider a modified sequential model to interpret our data. Two acetylcholine molecules bind sequentially to the receptor's resting state to form a pre-open (closed) state, which then opens and, at very high acetylcholine concentrations, is inhibited. A priori fast desensitization might occur from any of these acetylcholine-occupied states. If we assume fast desensitization to occur solely from the pre-open state, our data predict an excessively large action of ethanol on the fast desensitization rate constant (> 200-fold increase in the desensitization rate constant at 1 M ethanol). When we assume fast desensitization to occur from all states, ethanol is seen to have two actions.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1994

Requirement of 3'-terminal guanosine in (-)-stranded RNA for in vitro replication of cucumber mosaic virus satellite RNA by viral RNA-dependent RNA polymerase.

The 3' terminus of the (-) RNA strand in the replicative forms of several (+)-stranded RNA viruses possesses an unpaired guanosine with unknown function. This unpaired guanosine is also found at the 3' terminus of the (-) strand in the double-stranded form of two cucumoviral satellite RNAs. Using a cucumber mosaic virus (CMV) RNA-dependent RNA polymerase capable of replicating the satellite RNA in vitro, the 3'-terminal guanosine of the satellite (-) strand was shown to be an absolute requirement for satellite (+) strand synthesis. If genomic RNA synthesis of CMV and other members of the alphavirus-like superfamily that produce (-) strands terminating in an unpaired 3' guanosine follows a similar strategy, the work reported here would represent the first experimental support for the notion of 3'-terminal guanosine functioning as an essential recognition signal for viral replicases, enabling (+) strand RNA synthesis to be initiated internally from a (-) strand template.

Base Sequence↗
PubMed1994

Synthesis of citrulline from glutamine in pig enterocytes.

The synthesis of citrulline from glutamine was quantified in enterocytes from pre-weaning (14-21 days old) and post-weaning (29-58 days old) pigs. The cells were incubated at 37 degrees C for 30 min in Krebs-Henseleit bicarbonate buffer (pH 7.4) containing 0, 0.5, 2 and 5 mM glutamine. Oxygen consumption was linear during the 30 min incubation period. The rates of citrulline synthesis were low or negligible in enterocytes from 14-21-day-old pigs, but increased 10-20-fold in the cells from 29-58-day-old pigs. This marked elevation of citrulline synthesis coincided with an increase in the activity of pyrroline-5-carboxylate synthase with the animal's post-weaning growth. In contrast, decreases in the activities of phosphate-dependent glutaminase, ornithine aminotransferase, ornithine carbamoyltransferase and carbamoyl-phosphate synthase were observed as the age of the pigs increased. The concentrations of carbamoyl phosphate in enterocytes from pre-weaning pigs were higher than, or similar to, those in the cells from post-weaning pigs. It is possible that the low rate of citrulline synthesis from glutamine in enterocytes from pre-weaning pigs was due to a limited availability of ornithine, rather than that of carbamoyl phosphate. We suggest that this limited availability of ornithine in pre-weaning-pig enterocytes results from (i) the low rate of pyrroline-5-carboxylate synthesis from glutamate, due to the low activity of pyrroline-5-carboxylate synthase, and (ii) the competitive conversion of pyrroline-5-carboxylate into proline. Our present findings on the developmental aspect of citrulline synthesis in pig enterocytes may offer a biochemical mechanism for the previous observations that arginine is a nutritionally essential amino acid for suckling piglets, but not for adult pigs.

Ammonia↗