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Biomedical subjects

G Feng

Publications and source records attributed to G Feng.

At least 73 records · Page 4Linked to original sources
PubMed2000

Colchicine protects mice from the lethal effect of an agonistic anti-Fas antibody.

The aim of this study was to determine whether colchicine, which has been reported to protect against various hepatotoxic insults, influences the susceptibility of mice to the agonistic anti-Fas antibody, Jo2. All mice that were pretreated with colchicine (2 mg/kg) survived the lethal challenge of intraperitoneal administration of 10 microg of Jo2, whereas all control mice pretreated with gamma-lumicolchicine succumbed to the challenge. Twelve micrograms of Jo2 killed less than half of colchicine-pretreated mice and its lethal effects were delayed relative to control mice, which all died within 8 hours. Other microtubule-disrupting agents such as Taxol, vinblastine, and nocodazole also improved the survival of mice treated with the lethal dose of Jo2. Histologic examination showed that colchicine protected against Jo2-induced fulminant liver injury, and TUNEL assay demonstrated that colchicine protected against massive apoptosis of hepatocytes. Hepatocytes isolated from colchicine-pretreated mice exhibited decreased susceptibility to Jo2-induced apoptosis. In addition, colchicine pretreatment reduced surface expression of Fas and decreased Jo2- and TNF-alpha-induced apoptosis of cultured hepatocytes in the presence of actinomycin D, but did not affect the susceptibility of cultured sinusoidal endothelial cells to Jo2-induced apoptosis. Remarkably, Fas and TNF receptor-1 mRNA and intracellular protein levels increased after colchicine treatment, indicating that colchicine protects against death ligand-induced apoptosis in the liver by decreasing death-receptor targeting to the cell surface.

Animals↗
PubMed2000

Complete genomic sequence of 195 Kb of human DNA containing the gene GABRG2.

GABA (gamma-aminobutyric acid), as the main inhibitory neurotransmitter in the brain, plays an essential role for the overall balance between neuronal excitation and inhibition by acting on GABAA receptors, which are ligand-gated chloride channels. Impaired GABAergic function contributes to certain forms of epilepsy, schizophrenia, Alzheimer's Disease, and other neurological disorders. In order to identify possible genetic features and to further study biological regulation of GABAA receptor genes whose promoter elements and sequence anomalies may contribute to epileptic disorders, as an initial step, we shot-gun sequenced a BAC clone, dj082c10 (195,909-bp in size), encompassing human gamma(2) subunit of GABAA receptor (GABRG2). It is, we believe, the first genomic sequence of the GABA receptor gamma subunit family. Four contigs were assembled from 2950 reads prior to gap in an average redundancy of eight folds over the entire region. The precision of the consensus sequence was predicted to be 99.999% after closing gaps and finishing weak regions. The nine exons of GABRG2 spans an 85-kb region that had 81 SINEs comprising 22.32%, and nine L1 elements comprising 3.40%, respectively. However, the density of L1 in the regions flanking GABRG2 gene (29.45% by 45 elements) is significantly higher than that within the gene. The length of GABRG2 introns varies in the range of 1.5 kb to 38.1 kb.

Amino Acid Sequence↗
PubMed2000

[The role of membrane-type 1 matrix metalloproteinase in the invasion and metastasis of hepatocellular carcinoma].

OBJECTIVE: To study the role of membrane-type 1 matrix metalloproteinase (MT(1)-MMP) in the invasion and metastasis of hepatocellular carcinoma (HCC), and find a method to judge the invasion and metastasis of HCC through MT(1)-MMP. METHODS: RT-PCR was used to study the expression of MT(1)-MMP mRNA in the HCC and in HCC nude mice model with higher metastasis potential (LCI-D20) and lower metastasis potential (LCI-35), and statistical methods were used to analyse the association between the expression of MT(1)-MMP mRNA and the pathological indexes of HCC. RESULTS: MT(1)-MMP mRNA was expressed by all the normal liver tissue (1.12 +/- 0.73), HCC (3.51 +/- 0.97), surrounding liver parenchyma (1.19 +/- 0.57), tumor embolus, and HCC nude mice model with LCI-D20, LCI-D35. The overexpression of MT(1)-MMP mRNA in HCC, embolus, LCI-D20 was related to the invasion and metastasis of HCC. The expression of MT(1)-MMP mRNA in HCC being higher than that in surrounding liver parenchyma was an important index to judge the invasion and metastasis of the HCC. CONCLUSION: MT(1)-MMP is related to the invasion and metastasis of HCC. The expression of MT(1)-MMP mRNA in HCC being higher than that in surrounding liver parenchyma could be acted as an important index to judge the invasion and metastasis of HCC.

Animals↗
PubMed2000

[Effect of AM fungi on water and nutrition status of corn plants under salt stress].

Under NaCl stress, the dry matter production of corn plants inoculated with or without arbuscular mycorrhizal (AM) fungus (Glomus mosseae) was decreased, but the decrement for non-mycorrhizal plants was 10% higher than that for mycorrhizal ones. Under salt stress condition, the dry weights of root system and aboveground part of mycorrhizal corn and its leaf water potential were higher than those of non-mycorrhizal corn, while the proline content of mycorrhizal corn was less than that of non-mycorrhizal corn. The contribution of hypha to P uptake of plants decreased from 45.3% to 42.6%, while the effect of AM fungi on plant growth increased from 30.9% to 63.5% under salt stress condition. The above-mentioned results indicated that the mechanism that AM fungi enhance the salt-resistance of corn is related with the improvements of water and P nutrition conditions. Meanwhile, it was found whether under salt stress or not, the ratio of P accumulation of root system to aboveground part of mycorrhizal corn was higher than that of non-mycorrhizal corn, indicating that the infection of AM fungi changed the P distribution pattern in plant bodies, which is beneficial to increase the salt-resistance of plants.

Ecosystem↗
PubMed2000

[Expression and significance of MMP2 and type IV collagen in gastric cancer].

OBJECTIVE: To evaluate the relationship between the expression of MMP(2), type IV collagen, and invasion and metastasis of gastric cancer. METHODS: The expression of MMP(2) and Type IV collagen was observed by using immunohistochemistry technique. RESULTS: The MMP(2) expression clearly appeared in the poor-differentiated adenocarcinoma and tubular adenocarcinoma (85.7%, 77.7%). Type IV collagen destruction was observed simultaneously. MMP(2) was highly expressed in patients with cancer embolus in blood vessel and lymphatic vessel or with lymph node metastasis (83.3%, 86.7%). CONCLUSIONS: The high expression of MMP(2) was significantly associated with infiltration and metastasis of gastric cancer. The extracellular matrix, especially type IV collagen was destroyed in the cases of high expression of MMP(2). These results suggest that monitoring the level of MMP(2) expression may be an index for evaluation of prognosis.

Adenocarcinoma↗
PubMed2000

[Application of cellulose acetate membrane with the technique of impression cytology combined with immunohistochemical staining for detection of dry eye].

PURPOSE: To evaluate the conjunctival cells by impression cytology with cellulose acetate membrane. METHODS: The expression of the TGF-beta 1 in conjunctival epithelium of 24 patients with dry eye were studied by impression cytology combined with immunohistochemical staining and observed by microscope. RESULT: The cellulose acetate membrane is very transparent under the microscope. Cell's membrane by TGF-beta 1 staining is clear, cytoplasm brown and nuclei blue. CONCLUSION: The method of impression cytology with cellulose acetate membrane is simple and has no injury to the ocular surface. Combined with immunohistochemistry staining, it is suitable to observe the conjunctival cells by this technique which has an important value for the examination of the ocular surface disease.

Aged↗
PubMed1999

[Virus interaction in HBV and HCV super infection].

OBJECTIVE: To investigate virus interaction in HBV and HCV superinfection. METHODS: The changes of serum markers of 30 patients with HBV and HCV superinfetion were observed. Meanwhile, mutation of HBV precore region at nt 1,896 and the amount of TNF alpha and IL-6 in sera were also investigated. RESULTS: Compared with HBV or HCV single infection, positive rates of HBeAg, HBV DNA and HCV RNA in superinfectim were lower, positive rates of anti-HBe was higher, the average titers of HBsAg, anti-HBcIgG and anti-HCV were significantly lower, too. In some patients, HBsAg were seronegatively convested. Occurrence rate of HBV precore region mutation at nt1896 and levels of TNF alpha and IL-6 in sera were higher in super infection than those in single infection. CONCLUSION: Interference existed between HBV and HCV superinfection, conversion from HBeAg to anti-HBe was not only due to the suppression by HCV but also to the mutation of HBV precore region, and HCV may be a reason causing HBV precore region mutation through increasing the pressure of the body's immunosystem.

Adult↗
PubMed1999

Genetic analysis of collagen Q: roles in acetylcholinesterase and butyrylcholinesterase assembly and in synaptic structure and function.

Acetylcholinesterase (AChE) occurs in both asymmetric forms, covalently associated with a collagenous subunit called Q (ColQ), and globular forms that may be either soluble or membrane associated. At the skeletal neuromuscular junction, asymmetric AChE is anchored to the basal lamina of the synaptic cleft, where it hydrolyzes acetylcholine to terminate synaptic transmission. AChE has also been hypothesized to play developmental roles in the nervous system, and ColQ is also expressed in some AChE-poor tissues. To seek roles of ColQ and AChE at synapses and elsewhere, we generated ColQ-deficient mutant mice. ColQ-/- mice completely lacked asymmetric AChE in skeletal and cardiac muscles and brain; they also lacked asymmetric forms of the AChE homologue, butyrylcholinesterase. Thus, products of the ColQ gene are required for assembly of all detectable asymmetric AChE and butyrylcholinesterase. Surprisingly, globular AChE tetramers were also absent from neonatal ColQ-/- muscles, suggesting a role for the ColQ gene in assembly or stabilization of AChE forms that do not themselves contain a collagenous subunit. Histochemical, immunohistochemical, toxicological, and electrophysiological assays all indicated absence of AChE at ColQ-/- neuromuscular junctions. Nonetheless, neuromuscular function was initially robust, demonstrating that AChE and ColQ do not play obligatory roles in early phases of synaptogenesis. Moreover, because acute inhibition of synaptic AChE is fatal to normal animals, there must be compensatory mechanisms in the mutant that allow the synapse to function in the chronic absence of AChE. One structural mechanism appears to be a partial ensheathment of nerve terminals by Schwann cells. Compensation was incomplete, however, as animals lacking ColQ and synaptic AChE failed to thrive and most died before they reached maturity.

Acetylcholinesterase↗
PubMed1999

No association between the intronic presenilin 1 polymorphism and Alzheimer's disease in the Chinese population.

Wragg et al. [1996: Lancet 347:509-512] recorded an association between the intron-based presenilin 1 (PS1) genotype 1/1 and late-onset Alzheimer's disease (AD). This study was performed to determine if there is a similar association in the Chinese population. Ninety-one AD cases, 50 multiinfarct dementia (MID) patients, and 73 age-matched normal controls were recruited. Genotyping of PS1 and apolipoprotein E (APOE) was performed by the methods of polymerase chain reaction and restriction fragment length polymorphism. In AD, MID, and normal controls PS1 allele 1 frequency was 0.6703, 0.5600, and 0.6301, respectively; PS1 allele 2 frequency was 0.3297, 0.4400, and 0.3699, respectively. No association was detected between these diseases and any PS1 allele or genotype. There was only a nearly significant negative association between MID and PS1 genotype 1/1 in the subgroup population bearing APOE allele E4 (odds ratio = 0.2753, P = 0.0776). Our results do not support the conclusion that the intronic PS1 polymorphism is associated with Alzheimer's disease.

Aged↗
PubMed1999

Synapse formation by hippocampal neurons from agrin-deficient mice.

Agrin, a proteoglycan secreted by motoneurons, is a critical organizer of synaptic differentiation at skeletal neuromuscular junctions. Agrin is widely expressed in the nervous system so other functions seem likely, but none have been demonstrated. To test roles for agrin in interneuronal synapse formation, we studied hippocampi from mutant mice that completely lack the z+ splice form of agrin essential for neuromuscular differentiation and also exhibit severely ( approximately 90%) reduced levels of all agrin isoforms (M. Gautam et al., 1996, Cell 85, 525-535). The brains of neonatal homozygous agrin mutants were often smaller than those of heterozygous and wild-type littermates, but were morphologically and histologically indistinguishable. In particular, antibodies to pre- and postsynaptic components of glutamatergic synapses were similarly coaggregated at synaptic sites in both mutants and controls. Because mutants die at birth due to neuromuscular defects, we cultured neurons to assess later stages of synaptic maturation. In primary cultures, the agrin-deficient neurons formed MAP2-positive dendrites and tau-1-positive axons. Synaptic vesicle proteins, AMPA- and NMDA-type glutamate receptors, GABAA receptors, and the putative synapse-organizing proteins PSD-95, GKAP, and gephyrin formed numerous clusters at synaptic sites. Quantitatively, the number of SV2-labeled contacts per neuron at day 5 and the number of PSD-95 clusters per dendrite length at day 18 in culture showed no significant differences between genotypes. Furthermore, exogenous z+ agrin was unable to induce ectopic accumulation of components of central glutamatergic or GABAergic synapses as it does for neuromuscular cholinergic synapses. These results indicate that the z+ forms of agrin are dispensable for glutamatergic and GABAergic synaptic differentiation in the central nervous system.

Agrin↗
PubMed1999

When days are numbered: calendar structure and the development of calendar processing in English and Chinese.

Unlike English, Chinese uses a numerical system for naming months and days. This study explored whether this difference in naming affects the development of simple calendar calculation. Eight- and 10-year-old children as well as undergraduates in China and the United States were asked to name the day or month that comes a specified time before or after a given day or month. In each age group Chinese speakers primarily used calculation based on calendar names to solve these tasks, while English speakers primarily resorted to reciting the names. The magnitude of these differences was substantial; on difficult tasks Chinese fourth graders performed at speeds comparable to those of English-speaking adults. Implications for models of how linguistic structure affects cognition are discussed.

Child↗
PubMed1999

Preliminary clinical application of contrast-enhanced MR portography.

The clinical application of contrast enhanced (CE) MR was evaluated. A total of 66 CE MR portograms were obtained by performing fast imaging with steady procession (FISP) technique on a 1.5-T Siemens magnetom vision. A maximum intensity projection algorithm was also employed to include all vessels in a single image. The patency of portal venous system, the presence and extent of varices were also evaluated. The results showed that all images had diagnostic quality. Main portal vein (MPV) and its 4th-6th level intrahepatic branches were visualized in 10 normal persons serving as control. The diameter of MPV, splenic vein and superior mesenteric vein was 1.02 +/- 0.21, 0.8 +/- 0.15, 0.8 +/- 0.26 cm respectively, which were significantly lower than that in portal hypertension patients (1.38 +/- 0.27, 1.26 +/- 0.18, 1.24 +/- 0.18 cm, respectively). In 23 preoperative cases of portal hypertension, dilated portal vein and tortuous enlarged splenic vein were found in 23 cases; esophageal and coronary varices in 12 and 19 cases, respectively. In 7 postoperative re-examined cases with portal hypertension, the flow velocity and flow of MPV were decreased in all cases and esophageal varices could still be observed in 3 cases. New vessels appeared in the great curvature of stomach in 2 cases. In 20 cases of liver carcinoma, occlusion of MPV or its intrahepatic branches were showed in 14, compression and dislocation of intrahepatic portal vein were found in 6. In other 6 cases, 2 were splenic venous thrombosis and 4 were tumors in the intestine or retro-peritoneum. It is concluded that three-dimensional CE MR portography is an accurate technique for evaluating the portal venous system. It is a reliable and noninvasive technique that can provide important information for the evaluation of patients' condition before TIPSS and liver transplantation.

Contrast Media↗
PubMed1999

Endovascular irradiation prevents smooth muscle cell proliferation and neointimal hyperplasia in rabbits.

The present study examined the temporal responses and the efficacy of 192Ir-HDR endovascular irradiation for preventing smooth muscle cell proliferation of rabbit iliac arteries after PTA with a cutting balloon catheter. Endovascular irradiation with 12 Gy was randomly performed on the one side of iliac arterial segment with the unirradiated side serving as a control. Animals were euthanatized 1, 2, 3, 4, 8 and 12 week(s) after angioplasty. Histopathological and immunohistochemical studies were carried out. Histopathology showed repair of the dissection by cellular accumulation and a striking reduction in the amount of neointimal hyperplasia in the irradiated arteries as compared with control vessels. A peak of PCNA-positive ratio was in neointima of the control arterial segments at a week. 2-4 weeks after irradiation, the neointimal PCNA-positive ratio was still significantly increased in the control arterial segments compared with the irradiated arterial segments. After 8 weeks, PCNA-positive ratio was below 1% in both irradiated arterial segments and the control. Our results showed that the 192Ir-HDR afterloading irradiation with a dose of 12 Gy can be considered sufficient for inhibiting neointimal hyperplasia in angioplastized rabbit iliac arteries with cutting balloon catheter.

Angioplasty, Balloon, Coronary↗
PubMed1999

Mismatch repair is diminished during stationary-phase mutation.

This paper is an invited Response to a recent Commentary [P.L. Foster, Rev. Mut. Res. 436 (1999) 179-184] entitled "Are adaptive mutations due to a decline in mismatch repair? The evidence is lacking". The Commentary argues that no evidence exists supporting the idea that mismatch repair is limiting specifically during stationary-phase mutation. A primary concern of the author is to question the method that we used previously to measure growth-dependent mutation. In this method, mutation rates are calculated using counts of mutant colonies taken at times when those colonies arise, rather than at a predetermined, fixed time. Here we show further data that illustrate why this must be done to ensure accurate mutation measurements. Such accuracy was necessary for our published determination that mismatch repair proteins are not limiting during growth-dependent mutation, but become so during stationary-phase mutation. We review the evidence supporting the idea that stationary-phase reversion of a lac frameshift mutation occurs in an environment of decreased mismatch repair capacity. Those data are substantial. The data presented in the Commentary, in apparent contradiction to this idea, do not justify the conclusion presented there.

Adenosine Triphosphatases↗
PubMed1999

Tentative association of the serotonin transporter with schizophrenia and unipolar depression but not with bipolar disorder in Han Chinese.

The serotonin transporter gene (SERT) plays an important role in the serotonin uptake into neurons. Recently, several polymorphisms including a variable-number-tandem-repeat (VNTR) in the second intron and an insertion/deletion polymorphism (5-HTT linked polymorphic region, 5-HTTLPR) were identified and reported to be associated with a variety of mental illnesses, including major depression, bipolar disorder, anxiety-related traits, and autism. In our study, we performed an association study between the SERT VNTR polymorphism and schizophrenia (n = 260), bipolar disorder (n = 137), and unipolar depression (n = 33) in the Han Chinese. A large group of ethnically matched control individuals (n = 362) were also genotyped. Allele 12 of the VNTR polymorphism was associated with schizophrenia (P = 0.007) and unipolar depression (P = 0.011). Bipolar disorder was not associated with the VNTR (P = 0.93). Thus, we conclude that the SERT VNTR polymorphism may be a risk factor for both schizophrenia and unipolar depression, but not for bipolar disorder, in the Han Chinese.

Alleles↗
PubMed1999

[Study of the local anatomy and clinical practice about rhytidectomy of nasolabial fold].

OBJECTIVE: A technique is introduced to improve the operative result of rhytidectomy of the nasolabial fold. METHODS: Regional anatomy was studied on 10 adult cadavers together with histological examinations of tissue sections to investigate the formation mechanism of the nasolabial fold. 13 patients were operated on using a new technique of nasolabial fold rhytidectomy. RESULTS: Prolonged and repeated movements of the facial mimetic muscles produce a shearing force between the skin-subcutaneous tissue and the SMAS-mimetic muscles, causing relative motion of adjacent tissues with different structure at the site of the nasolabial fold, thus producing the nasolabial fold. In clinical application of the finding, the nasolabial folds of 13 patients were corrected with remarkable early and long-term results postoperatively. CONCLUSION: The operation should be performed between SMAS and the subcutaneous tissue. SMAS should be incised along the zygomatic major muscle. The fibro-fatty zygomatic pad should be replaced anatomically and the zygomatic ligament be reconstructed.

Adult↗
PubMed1999

[Analysis of 2-acrylamido-2-methyl propane sulfonic acid by thin layer chromatography].

A method for the analysis of 2-acrylamido-2-methyl propane sulfonic acid(AMPS) by TLC is described. The plate was Silica GF254. We selected benzene/methanol as developing agent from several developing systems and fixed the best ratio: V(benzene):V(methanol) = 2:1. The experiment indicated that the Rf value of AMPS was 0.36 while that of AM(acrylamide), the main impurity in crude AMPS sample, was 0.64. The minimum detectable limit of AMPS was 5 micrograms and the developing time was about 25 minutes. Compared with ether/methanol and chloroform/methanol, benzene/methanol system has the advantages of more easily controlling its ratio, better repeatability and much rapid developing rate. This method may be helpful in the control of AMPS in quality.

Acrylamides↗