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Biomedical subjects

G Feng

Publications and source records attributed to G Feng.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Effect of VAM fungi on phosphatase activity in maize rhizosphere].

The effect of VAM fungi on phosphatase activity in maize rhizosphere was examined by pot culture experiment, in which, three-compartment-pots were used, the central compartment being separated from the outer two by a nylon net with 30 microns mesh. Plants were harvested 70 days after planting. Soil acid and alkaline phosphatase were measured at different distances from root surface. The results showed that VAM increased the activities of soil acid and alkaline phosphatase in the rhizosphere. It was found that different phosphorous sources had different effects on phosphatase activity.

Ecosystem↗
PubMed2001

[A study on the resistance of Staphylococcus aureus and the mechanisms of its resistance to fluoroquinolone].

OBJECTIVE: To investigate the resistance of Staphylococcus aureus(SA) and the mechanisms of its resistance to fluoroquinolones (FQ). METHODS: The susceptibility of SA (200 strains) to 12 antibiotics was detected by disc diffusion, The minimal inhibitory concentrations (MICs) of 52 strains to three FQ were determined by agar dilution method. 52 strains resistant to ciprofloxacin (MIC> or =4 mg/L) were studied for the presence of point mutations in the gyrA gene and grlA gene by polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) method and for the expression of norA gene by reserpine reverse test respectively. RESULTS: 34% of the strains were resistant to oxacillin(methicillin resistant Staphylococcus aureus, MRSA) and other antimicrobials as well, but no vancomycin resistant strain was found. The resistance rate of MRSA to ciprofloxacin was 79.4% and cross-resistance existed. It was found that 42 strains (80.8%) had a mutation at gyrA codon 84 (TCA-->TTA or GCA). Mutations at grlA codon 80 (TCC-->TAC or TTC) and codon 84 (GAA-->AAA)were observed in 10 (19.2%) and 14 strains(26.9%) respectively.Strains containing mutations in gyrA or both gyrA and grlA gene showed a higher level of ciprofloxacin resistance than those with alternation in grlA gene but with wild type gyrA or non-gyrA mutants (P < 0.01). Decreased MICs to ciprofloxacin, norfloxacin and levofloxacin in reserpine reverse test indicated the presence of norA phenotype. CONCLUSIONS: It is clear that emergence of resistant SA strains will continue to be a problem, especially in MRSA which was resistant to most of the antibiotics. Fluoroquinolones are not the choice for MRSA now. The resistance to fluoroquinolones in clinical isolates of SA are due to the mutations of the gyrA and grlA gene encoding the target enzyme of fluoroquinolones and cell membrane resistance. Mutations of grlA gene may differ in different districts.

Anti-Infective Agents↗
PubMed2001

[Amplifying variable region gene of light chain of monoclonal antibody against human retinoblastoma by PCR].

OBJECTIVE: To acquire the variable region gene of light chain of monoclonal antibody against human retinoblastoma. METHODS: Total RNA were extracted from hybridoma cells secreting specific monoclonal antibody(McAb) against human retinoblastoma(RB), then transcripted reversely into cDNA with random primers. The variable region of the light chain(VL) gene fragments were ampliflied using polymerase chain reaction(PCR) method. Agrose gel electrophoresis was confirmed. RESULTS: 1.5% agrose gel electrophoresis indicated that VL gene was about 340 base pairs. CONCLUSION: The light chain variable region gene of the McAb against human RB was amplified successfully, which lays a good basis for construction of a recombinant antibody.

Antibodies, Monoclonal↗
PubMed2001

Histopathological study of trabeculum after excimer laser trabeculectomy ab interno.

PURPOSE: To study the clinical manifestations and histopathologic changes of trabeculum after excimer laser trabeculectomy ab interno (ELT), and to investigate the mechanisms of ELT in reducing intraocular pressure. METHODS: ELT was performed on ten rabbit eyes and postoperative responses were documented. Corneoscleral tissue samples were harvested consecutively each week until the 5th postoperative week and these samples were examined under light and electrical microscopy. RESULTS: Mild stimulation signs were present postoperatively in nine of ten eyes, but no serious complications were experienced. Obvious inflammation was observed in one rabbit eye as a result of iris damage during the surgical manipulations. Local fractures on the trabecular meshwork and openings into Schlemm's canal were detected in all tissue samples under light microscope. Mitochondria were found to be turgescent and dilated like vacuoles and endoplasmic reticula were found to be dilated under electrical microscope in the early postoperative period. Later, all trabecular cells returned normal and no fibroblast cells were ever detected. CONCLUSIONS: Permanent openings through trabecular meshwork into the inner wall of Schlemm's canal can be created with ELT. The outflow resistance of aqueous humor can be reduced with these openings and intraocular pressure can be controlled thereafter.

Animals↗
PubMed2001

Experiment study of effect of perfluorohexyloctane on corneal endothelial cells.

PURPOSE: To investigate the effect of Perfluorohexyloctane (F6H8) on corneal endothelial cells(CEC) of rabbit eyes. METHODS: Fifteen New Zealand white rabbits were divided into two groups: experimental group(F6H8) and control group(BSS). All rabbits underwent anterior chamber injection of 0.15 ml F6H8 or BSS. Slit-lamp biomicroscopy and corneal endothelium photography were performed pre-operatively and postoperatively. Histopathological examination and Transmission electron microscopy(TEM) were done after the rabbits were sacrificed. RESULTS: All the corneas were clear. Since 4 weeks after operation, the endothelial cells were markedly irregular in size and shape and the number of endothelial cells was markedly decreased. Multilayered retrocorneal membranes(RCM) grew gradually 2 weeks after surgery. Vacuolar degeneration was seen in some endothelial cells. Nuclear degeneration and edema of plasma were seen in TEM. CONCLUSION: Corneal endothelial cell degenerated after contacting with F6H8 for 2-4 weeks. As a silicone solvent, it should be removed completely after injection. We don't recommend it to be used as a new intraocular temponade.

Animals↗
PubMed2001

Pathological, ultrastructural and immunohistochemical observations of adenoma of retinal pigment epithelium.

PURPOSE: To Study the clinical, pathological, ultrastructural and immunohistchemical characters of adenoma of the retinal pigment epithelium in order to offer evidence to diagnose this tumor. METHODS: Routine paraffin slices HE stain, histochemistry PAS and VG stain, transmission electron microscopy, and immunohistochemistry for S-100 and vimentin with LSAB method were used. RESULTS: The tumor cells were oval and cuboidal in shape. Part of the tumor had a tubular arrangement. Around the sheets of tumors cells there was a large amount of uniform red stick-like substances. The above matter represented positive in PAS stain. Most of the above matter was yellow, while less of the matter showed red in VG stain. Transmission electron microscopy showed that there were tight junctions between tumor cells. Immunohistochemistry showed positive for S-100, negative for vimentin. CONCLUSIONS: The ultrastructural and immunohistochemical characters of the adenoma of retinal pigment epithelium are consistent with the retinal pigment epithelium.

Adenoma↗
PubMed2001

[Study on the dynamic changes of retinoblastoma gene of SO-Rb50 cell line].

PURPOSE: To study the dynamic changes of Retinoblastoma Gene of SO-Rb50 cell line. METHODS: 1) Southern blot hybridization was used to analyse the tumor cell DNA of 327th passage of SO-Rb50 cell line. 2) A promoter and 27 exons of Rb gene were screened exon-by-exon by using PCR-SSCP at 415th and 713th passages of SO-Rb50 cell line. 3) Three cell cloning strains named as MC2, MC3 and MC4 were isolated by single cell cloning technique from the SO-Rb50-775, and mutation of Rb gene were also screened exon-by-exon by using PCR-SSCP-HA in MC2-11, MC3-11, MC4-11 and MC3-138. RESULTS: The 3.5 Kb, 2.9 Kb and 1.0 Kb bands were deleted in the DNA of SO-Rb50-327 tumor cells, showing the deletion of Rb gene in SO-Rb50 cell line. Exon23 of 451th passage cells decreased one band; but exon 25 of 713th passage cells decreased two bands, indicating that exon 25 had new mutation. PCR-SSCP-HA analysis of exon24 showed that MC4-11 and MC3-138 had abnormal bands, but MC2-11 and MC3-11 weren't found mutation of Rb gene. This result suggested that new mutation occurred to exon24 of MC3 during a long-term culture in vitro. CONCLUSION: Retinoblastoma gene mutation of SO-Rb50 cell line had dynamic changes during a long-term culture.

Exons↗
PubMed2001

[Study on the inclusion interaction of beta-cyclodextrin with phosphatidylcholine by UV spectra].

A kind of cyclic oligosaccharides, beta-cyclodextrin (beta-CD) was found to possess inclusion ability with phosphatidylcholine (PC). The inclusion compound of beta-CD with PC was studied by elemental analysis of solid inclusion compound and UV spectra of different mole ratios beta-CD/PC in H2O-MeOH solution. The results indicate that two moles of beta-CD include one mole PC to form inclusion compound by Van Der Waals force, hydrophobic interaction and hydrogen bounds, etc. The selective binding ability of beta-CD with PC has been discussed from the viewpoint of size/shape-fitting and geometry fitting between the host cavity and the gust molecular. The solubility in aqueous solution, the oxidation stability of PC was increased by inclusion with beta-CD.

Chemical Phenomena↗
PubMed2000

Association between angiotensin-converting enzyme gene and late onset Alzheimer's disease in Han chinese.

There is now overwhelming evidence that the varepsilon4 allele of apolipoprotein (APOE) gene is a major risk factor for late-onset Alzheimer's disease (AD). However, the APOE locus only accounts for a proportion of the overall genetic risk for AD. The angiotensin-converting enzyme (ACE) is widely expressed in the brain and may have a role in AD. Recently an insertion/deletion (I/D) DNA polymorphism at the intron 16 of ACE gene has been found associated with late-onset AD, but the results are not consistent. We have examined ACE gene in a cohort of Han Chinese AD cases and controls. We have found the ACE-I allele was enriched in our cases compared to controls (odds ratio (OR)=2.09, P=0.0043). The phenomenon was restricted to cases presenting with AD after the age of 70 years (P<0.0005), and was independent of APOE genotype. We conclude that ACE genotype is a risk factor for late onset AD.

Age Factors↗
PubMed2000

Congenital absence of permanent teeth in a six-generation Chinese kindred.

We report on rare, heritable, permanent tooth agenesis in a large Chinese kindred. The congenital absence of permanent teeth except the first and second accessory teeth was observed in 52 individuals through six successive generations in the kindred comprising 328 members. Clinical assessments were carried out, and inheritance mode and spousal influence of the anomaly on their offspring were analyzed. Consequently, the anomaly was transmitted in an autosomal dominant fashion with incomplete penetrance (P = 0.88), and no significant clinical manifestations other than the oligodontia were found. A geographical or environmental effect on the affected individuals was obviously eliminated, because any who are related to the kindred but live under the same conditions are fully healthy. The disorder we describe, therefore, differs from any previously reported oligodontia/anodontia syndromes. The oligodontia ranged from a few teeth to the whole set of teeth, and usually occurred at a period from age 7 or 8 years, the time when primary teeth are normally replaced by permanent teeth, to the forties. Roentgenography of the affected persons indicated that only the first and/or second accessory teeth with tooth buds developed as permanent teeth. In fact, the diphyodontic germination sometimes occurred in the oral cavity of the affected individuals.

China↗
PubMed2000

[CT virtual endoscopy: A study of the capability to display the structures and abnormalities in nasal cavity].

To evaluate displaying ability of virtual endoscopy and its clinical application in comparison with fiberoptic nasal endoscopy, 11 patients (22 nasal cavities) were examined by virtual endoscopy after axial spiral CT scanning was performed. Virtual endoscopy was performed by Explorer software package in a computer workstation. 9 patients (18 nasal cavities) underwent fiberoptic endoscopy. Results showed virtual endoscopy could clearly demonstrate the anatomical structures in nasal cavity, septal deviation, nasal meatus narrowing and obstruction, turbinate hyperplasia, and pathological masses larger than 3 mm in diameter. However, the "false adhesions" may appear with virtual endoscopy. The main limitation of virtual endoscopy was inability to evaluate mucosa and lack of histological diagnosis. Virtual endoscopy is a new and non-invasive method for demonstrating anatomical structures and diseases in nasal cavity. Its displaying ability is comparable with fiberoptic nasal endoscopy. It can serve as a supplementary method of fiberoptic nasal endoscopy.

Adult↗
PubMed2000

Imaging neuronal subsets in transgenic mice expressing multiple spectral variants of GFP.

We generated transgenic mice in which red, green, yellow, or cyan fluorescent proteins (together termed XFPs) were selectively expressed in neurons. All four XFPs labeled neurons in their entirety, including axons, nerve terminals, dendrites, and dendritic spines. Remarkably, each of 25 independently generated transgenic lines expressed XFP in a unique pattern, even though all incorporated identical regulatory elements (from the thyl gene). For example, all retinal ganglion cells or many cortical neurons were XFP positive in some lines, whereas only a few ganglion cells or only layer 5 cortical pyramids were labeled in others. In some lines, intense labeling of small neuronal subsets provided a Golgi-like vital stain. In double transgenic mice expressing two different XFPs, it was possible to differentially label 3 neuronal subsets in a single animal.

Animals↗
PubMed2000

Roles for ephrins in positionally selective synaptogenesis between motor neurons and muscle fibers.

Motor axons form topographic maps on muscles: rostral motor pools innervate rostral muscles, and rostral portions of motor pools innervate rostral fibers within their targets. Here, we implicate A subfamily ephrins in this topographic mapping. First, developing muscles express all five of the ephrin-A genes. Second, rostrally and caudally derived motor axons differ in sensitivity to outgrowth inhibition by ephrin-A5. Third, the topographic map of motor axons on the gluteus muscle is degraded in transgenic mice that overexpress ephrin-A5 in muscles. Fourth, topographic mapping is impaired in muscles of mutant mice lacking ephrin-A2 plus ephrin-A5. Thus, ephrins mediate or modulate positionally selective synapse formation. In addition, the rostrocaudal position of at least one motor pool is altered in ephrin-A5 mutant mice, indicating that ephrins affect nerve-muscle matching by intraspinal as well as intramuscular mechanisms.

Animals↗
PubMed2000

Autoimmunity to gephyrin in Stiff-Man syndrome.

Stiff-Man syndrome (SMS) is a rare disease of the central nervous system (CNS) characterized by chronic rigidity, spasms, and autoimmunity directed against synaptic antigens, most often the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD). In a subset of cases, SMS has an autoimmune paraneoplastic origin. We report here the identification of high-titer autoantibodies directed against gephyrin in a patient with clinical features of SMS and mediastinal cancer. Gephyrin is a cytosolic protein selectively concentrated at the postsynaptic membrane of inhibitory synapses, where it is associated with GABA(A) and glycine receptors. Our findings provide new evidence for a close link between autoimmunity directed against components of inhibitory synapses and neurological conditions characterized by chronic rigidity and spasms.

Animals↗
PubMed2000

A locus for brachydactyly type A-1 maps to chromosome 2q35-q36.

Brachydactyly type A-1 (BDA1) was, in 1903, the first recorded example of a human anomaly with Mendelian autosomal dominant inheritance. Two large families, the affected members of which were radiographed, were recruited in the study we describe here. Two-point linkage analysis for pedigree 1 (maximum LOD score [Zmax] 6.59 at recombination fraction [theta] 0.00) and for pedigree 2 (Zmax=5.53 at straight theta=0.00) mapped the locus for BDA1 in the two families to chromosome 2q. Haplotype analysis of pedigree 1 confined the locus for family 1 within an interval of <8.1 cM flanked by markers D2S2248 and D2S360, which was mapped to chromosome 2q35-q36 on the cytogenetic map. Haplotype analysis of pedigree 2 confined the locus for family 2 within an interval of <28. 8 cM flanked by markers GATA30E06 and D2S427, which was localized to chromosome 2q35-q37. The two families had no identical haplotype within the defined region, which suggests that the two families were not related.

Adolescent↗
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↗