Biomedical subjects

Q Tang

Publications and source records attributed to Q Tang.

At least 37 records · Page 2Linked to original sources

PubMed2001

Elimination of active tad elements during the sexual phase of the Neurospora crassa life cycle.

Tad is an active LINE-like retrotransposon isolated from the Adiopodoumé strain of Neurospora crassa. Extensive analysis of other Neurospora strains has revealed no other strain with active Tad, but all strains tested have multiple copies of defective Tad elements. We have examined the ability of Tad to survive during the sexual cycle of Neurospora and find that active Tad is rapidly eliminated. The characteristics of this elimination suggest that the repeat-induced point mutation (RIP) mechanism was responsible. By the use of transformation to switch the mating type of the Adiopodoumé strain we concluded that this strain is not defective in the RIP process. Analysis of defective Tad elements isolated from a variety of strains indicates that the major difference between these elements and active Tad is due to the presence of a large number of G-C to A-T transition mutations. This would be expected if the changes were due primarily to the RIP process. Mapping of a selection of defective Tad elements reveals that they are present on all of the chromosomes; however, many of the elements are not widely shared among strains. This suggests that repeated introduction and elimination of Tad elements has occurred. Mechanisms that might be responsible for this repeated introduction are discussed.

Blotting, Southern↗

PubMed2001

Vesicle trafficking and cell surface membrane patchiness.

Membrane proteins and lipids often appear to be distributed in patches on the cell surface. These patches are often assumed to be membrane domains, arising from specific molecular associations. However, a computer simulation (Gheber and Edidin, 1999) shows that membrane patchiness may result from a combination of vesicle trafficking and dynamic barriers to lateral mobility. The simulation predicts that the steady-state patches of proteins and lipids seen on the cell surface will decay if vesicle trafficking is inhibited. To test this prediction, we compared the apparent sizes and intensities of patches of class I HLA molecules, integral membrane proteins, before and after inhibiting endocytic vesicle traffic from the cell surface, either by incubation in hypertonic medium or by expression of a dominant-negative mutant dynamin. As predicted by the simulation, the apparent sizes of HLA patches increased, whereas their intensities decreased after endocytosis and vesicle trafficking were inhibited.

Biological Transport↗

PubMed2001

ERM-dependent movement of CD43 defines a novel protein complex distal to the immunological synapse.

The large mucin CD43 is actively excluded from T cell/APC interaction sites, concentrating in a membrane domain distal to the site of TCR engagement. The cytoplasmic region of CD43 was necessary and sufficient for this antipodal movement. ERM cytoskeletal adaptor proteins colocalized with CD43 in this domain. An ERM dominant-negative mutant blocked the distal accumulation of CD43 and another known ERM binding protein, Rho-GDI. Inhibition of ERM function decreased the production of IL-2 and IFNgamma, without affecting PKC(theta) focusing or CD69 upregulation. These results indicate that ERM proteins organize a complex distal to the T cell/APC interaction site and provide evidence that full T cell activation may involve removal of inhibitory proteins from the immunological synapse.

Animals↗

PubMed2001

[Assay of trace elements and heavy metals in different growth stages of Ganoderma lucidum].

The trace elements and heavy metals in the different growth stages of Ganoderma lucidum were analyzed by ICP-MS, AFS and AAS. The fermented mycelia, fruiting bodies and spore contained all kinds of detected trace elements and heavy metals, the contents of which were higher in spore. The content of Se was same in different growth stages. Ganoderma lucidum had the ability of bio-enrichment of Ge.

Fruit↗

PubMed2001

[Maintenance ration and conversion efficiency of Hyporhamphus sajori].

The maintenance ration and conversion efficiency of Japanese halfbeak, Hyporhamphus sajori were tested with enclosures installed in a shrimp raising pond. The results showed that there existed an evident relationship between daily ration(DR) and growth rate(GR) of the fish, GR = 140.37 DR - 24.03. The conversion efficiency was 13.96% in biomass or 16.12% in energy. The maintenance ration was 17.12% and 20.39% of body weight in terms of growth rate and specific growth rate, respectively, indicating that it could be deduced from growth rate quite differently from that from specific growth rate in the same experiment. The abnormal growth rate appeared when daily ration was below 3.30% of body weight, implied that Japanese halfbeak may get other food resources besides supplied net zooplankton.

Animals↗

PubMed2001

[Analysis on the present situation of human rabies epidemic in China].

OBJECTIVE: To summarize and analyze human rabies epidemic situation in the last five years in China and to explore the possible factors causing the rising of epidemics to provide reference for the prevention and control of rabies in the future. METHODS: Collecting and analyzing data of rabies epidemics in the last five years in whole nation. RESULTS: Human rabies is continuing going up in the last five years in China with an increase of 44.65%, 1.74% and 45.93% in 1997, 1998, 1999. Human rabies incidence was also seen an increase from 0.0134/100,000 in 1996 to 0.02708/100,000 in 1999. The provinces of rabies increase were mainly located in south China. Among them, Jiangsu province reported 40 human cases in 1999, which increased 207.69% than the corresponding period in 1998. The cases in these high epidemic provinces took up 75% of the whole nation's cases. Number of reported rabies case was also rising. CONCLUSION: Facts as increasing number of dog raising, having not been injected with rabies vaccine and antirabies serum timely or full course after exposure, unstrictly controlling the quality of rabies vaccine as well as lacking good cooperation in different official department on rabies control might serve as factors responsible for the recurrent increase of human rabies.

Animals↗

PubMed2001

[Studies on calluses induced from various explants of Cistanche deserticola].

Calluses were induced from various explants (flower, stem, bud and squama) of Cistanche deserticola Y.C.Ma and compared with each other. The result showed that the inducement rate of ovary and stem were higher than that of other explants which the inducement time was short and the characters of calluses were good. The effect of basal culture medium added hormone on callus reproduction was also studied. The result showed that B5 culture medium added 1 mg/L IBA and 2 mg/L 6-BA was optimal.

Cistanche↗

PubMed2000

Capillary electrochromatography using continuous-bed columns of sol-gel bonded silica particles with mixed-mode octadecyl and propylsulfonic acid functional groups.

Continuous-bed columns containing sol-gel bonded 3 microm silica particles with mixed-mode octadecyl and propylsulfonic acid functional groups (ODS/SCX) were prepared by first packing the ODS/SCX particles into a fused-silica capillary, then filling the packed capillary with a siliceous sol-gel, curing the sol-gel, and finally drying the column with supercritical carbon dioxide. The performance of the sol-gel bonded ODS/SCX columns was evaluated for capillary electrochromatography using acetonitrile aqueous mobile phase containing phosphate buffer. The columns were mechanically strong and permeable. Both EOF velocity and current increased linearly with elevation of the applied electric field strength. The EOF velocity was high at low pH and nearly constant over a range of pH 2-9. Higher buffer concentration resulted in higher current and lower EOF velocity. The acetonitrile content had no significant effect on the EOF. Without thermosetting the column, no bubble formation was noticed with currents up to 2.5 microA. The minimum plate height of a 25/34 cm x 75 microm I.D. sol-gel bonded 3 microm ODS/SCX column was 5.7 microm (1.75 x 10(5) plates per meter) at an optimum EOF velocity of 0.92 mm s(-1). Mixtures of test aromatic compounds and aromatic hydrocarbon homologues gave symmetrical peaks when using a low pH mobile phase. The retention and elution order of aromatic compounds represented a typical reversed-phase separation mechanism similar to conventional ODS columns. The run-to-run and column-to-column retention factor reproducibility was better than 2.5% and 8.0% RSD, respectively.

Acetonitriles↗

PubMed2000

Replication but not transcription of simian virus 40 DNA is dependent on nuclear domain 10.

DNA viruses from several families including herpes simplex virus type 1, adenovirus type 5, and simian virus 40 (SV40), start their transcription and replication adjacent to a specific nuclear domain, ND10. We asked whether a specific viral DNA sequence determines the location of these synthetic activities at such restricted nuclear sites. Partial and overlapping SV40 sequences were introduced into a beta-galactosidase expression vector, and the beta-galactosidase transcripts were localized by in situ hybridization. Transcripts derived from control plasmids were found throughout the nucleus and at highly concentrated sites but not at ND10. SV40 genomic segments supported ND10-associated transcription only when the origin and the coding sequence for the large T antigen were present. When the large T-antigen coding sequence was eliminated but the T antigen was constitutively expressed in COS-7 cells, the viral origin was sufficient to localize transcription and replication to ND10. Deletion analysis showed that only the large T-antigen binding site II (the core origin) was required but the T antigen was needed for detectable transcription at ND10. Large T antigen expressed from plasmids without the viral core origin did not bind or localize to ND10. Blocking of DNA replication prevented the accumulation of transcripts at ND10, indicating that only sites with replicating templates accumulated transcripts. Transcription at ND10 did not enhance total protein synthesis of plasmid transcripts. These findings suggest that viral transcription at ND10 may only be a consequence of viral genomes directed to ND10 for replication. Although plasmid transcription can take place anywhere in the nucleus, T-antigen-directed replication is apparently restricted to ND10.

Animals↗

PubMed2000

Dynorphin A elicits an increase in intracellular calcium in cultured neurons via a non-opioid, non-NMDA mechanism.

The opioid peptide dynorphin A is known to elicit a number of pathological effects that may result from neuronal excitotoxicity. An up-regulation of this peptide has also been causally related to the dysesthesia associated with inflammation and nerve injury. These effects of dynorphin A are not mediated through opioid receptor activation but can be effectively blocked by pretreatment with N-methyl-D-aspartate (NMDA) receptor antagonists, thus implicating the excitatory amino acid system as a mediator of the actions of dynorphin A and/or its fragments. A direct interaction between dynorphin A and the NMDA receptors has been well established; however the physiological relevance of this interaction remains equivocal. This study examined whether dynorphin A elicits a neuronal excitatory effect that may underlie its activation of the NMDA receptors. Calcium imaging of individual cultured cortical neurons showed that the nonopioid peptide dynorphin A(2-17) induced a time- and dose-dependent increase in intracellular calcium. This excitatory effect of dynorphin A(2-17) was insensitive to (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]-cyclohepten-5,10-imine (MK-801) pretreatment in NMDA-responsive cells. Thus dynorphin A stimulates neuronal cells via a nonopioid, non-NMDA mechanism. This excitatory action of dynorphin A could modulate NMDA receptor activity in vivo by enhancing excitatory neurotransmitter release or by potentiating NMDA receptor function in a calcium-dependent manner. Further characterization of this novel site of action of dynorphin A may provide new insight into the underlying mechanisms of dynorphin excitotoxicity and its pathological role in neuropathy.

Animals↗

PubMed2000

[Clinical study on morphological characteristics of placenta in severe pregnancy induced hypertension].

OBJECTIVE: To study morphological characteristics of placenta in severe pregnancy induced hypertension (SPIH) and its relationship to pregnant outcome. METHODS: Morphological changes were observed by light microscopy; Blood biochemical analyses were used to predispose pregnant outcome. RESULTS: Difference in pathological changes of placental bed between normal term pregnancy (NTP) and SPIH groups was significant: the placental weight, proliferation of cytotrophoblasts, numbers of the placental villi with syncytial knots, thickness of basal lamina, fibrinoid necrosis and deposition of matrix, stromal edema and fibrosis of villi, the vascular numbers of villi, stasis; lack of physiologic changes in decidual spiral arteries. Clinical examination showed that the rate of anemia, thrombocytopenia, blood concentration, hypoproteinemia, ascites, eye ground artery spasm in SPIH were higher in NIT. CONCLUSIONS: Pathological changes of placenta play important roles in development of SPIH, and the pathological changes are paralleled with the severity of the disease.

Adult↗

PubMed2000

[Environmental characteristic of walleye pollock fishing ground in high seas of the Okhotsk Sea in summer].

Based on the acoustic survey on the resource of walleye pollock (Theragra chalcogramma) in the high seas of the Okhotsk Sea, the distribution of walleye pollock and the environmental characteristics of its fishing ground were studied, and the relationship between them were analyzed. In August, the high schooling area of walleye pollock was situated in the waters with a depth of less than 500 meters and to the north of 55 degrees N. Walleye pollock mainly distributed in 150-300 m depth, and lived in groups. The main food was Euphausia pacifica, and the densely populated area of wall-eye pollock was roughly consistent with that of Euphausia pacifica. The thermocline was observed at 0-50 m depth, the temperature changed at a rate of 0.25 degree C per meter, and the cold water mass was roughly located in 50-150 m layer. The fish was mainly distributed in the layer below the cold water mass, because of the impeding effect of thermocline and the limiting action of fish food. It seldom inhabited the water below 400 m depth, partly because the dissolved oxygen there was rather low.

Animals↗

PubMed2000

[Gastric evacuation rate of black sea bream(Sparus macrocephalus)].

The gastric evacuation rate of black sea bream(Sparus macrocephalus) weighing 20-40 g was determined at 18 degrees C in laboratory. Three mathematical models were applied to simulate it. The result indicated that all of these three kinds of models fitted to the experiment data, while statistical analysis showed that the linear model was the best, whether the remained food in stomach was expressed by wet weight or dry weight. When the remained food in stomach was expressed by wet weight, the model was Y = 1.14 - 0.06 t(r2 = 0.82, p < 0.001), and by dry weight, it was Y = 1.36 - 0.07 t(r2 = 0.62, p < 0.001). The gastric evacuation rate of black sea bream was 6-7% of consumed food per hour at 18 degrees C.

Animals↗

PubMed2000

A preliminary approach on mass-balance ecopath model of the Bohai Sea.

A Bohai Sea mass-balance ecopath model is constructed on the basis of fisheries resources data from the ecosystem survey conducted from April 1982 to May 1983. It is the first ecopath model which consists of 13 function groups (boxes), and only covers the main trophic flow in the Bohai Sea ecosystem. P/B and Q/B parameters (P: production, B: biomass, Q: consumption) for most groups were estimated from similar function groups in other ecopath models of the same latitude regions around. The value of EE (Ecotrophic Efficiency) is the main parameter to check the equilibration of the model. The EE parameters in the model are of high value (> 0.808) for most groups, because the fishing pressure was very high and small living organisms were being heavily preyed upon in the ecosystem. The biomass density of the species commercially utilized estimated by the model is 12.33 ton.km-2. Even though the value is low compared with the density in other ecosystems, such as Caribbean coral reef ecosystem and the Southern B.C. shelf model, it is higher than the value published by some papers on the Bohai Sea using other methods. Considering the lower value estimated by the stock assessment using bottom trawl survey data, the output here is reasonable. It is concluded that the biomass of commercial fishing species in the sea is 950 thousand metric tons, and 338 thousand tons are fish species in the value.

Animals↗

PubMed2000

[Assimilation efficiency of pacific oyster Crassortrea gigas].

The effects of body size, food density and its quality on assimilation efficiency of pacific oyster (Crassostrea gigas) were studied under artificial conditions in laboratory. The experimental results show that the filtration and ingestion rates of pacific oyster increased with its body size, which tallied with power function. The assimilation efficiency of pacific oyster was not significantly correlated with its body size, but correlated positively with the organic matter content of food and negatively with food density.

Animal Nutritional Physiological Phenomena↗

PubMed2000

[Effect of gandou decoction on copper metabolism of skin fibroblast of hepatolenticular degeneration model].

OBJECTIVE: To explore the cytological mechanism of Gandou Decoction (GDD) in treating hepatolenticular degeneration (HLD). METHODS: Twenty-three in vitro models of cultured skin fibroblast of HLD were established to observe the intracellular change of microelements (Cu2+, Zn2+, etc.) content before and after adding rabbit's serum containing GDD. RESULTS: After being treated with GDD contained serum for 24 hours, the intracellular content of Cu2+ decreased from (80.94 +/- 34.76) ng/mg to (46.90 +/- 22.14) ng/mg, P < 0.01, while that of Zn2+ increased from (140.43 +/- 33.81) ng/mg to (151.43 +/- 37.83) ng/mg, P < 0.01. CONCLUSION: GDD is quite effective in removing the intracellular copper and increasing the intracellular zinc.

Adolescent↗

PubMed2000

[An electron microscopic histochemical study on the fibrous formation in pleomorphic adenoma of the salivary gland].

OBJECTIVE: To study the kinds of fibers and mechanism of fibrous formation in myxochondroid tissue of pleomorphic adenoma. METHODS: Eight cases of pleomorphic adenomas of salivary gland were studied by histological and electron microscopic histochemical techniques. RESULTS: The histological study showed that collagenous fibers and elastic fibers which constituted the trestle were distributed in myxochondroid areas of pleomorphic adenoma. The electron microscopic histochemical study showed that the myxochondroid tissue contained slender collagen fibrils measuring 50 nm in diameter and heavily stained elastic fibers. In cytoplasm of the myxochondroid cells two types of the Golgi-derived vesicles were seen: one was small round vesicles with a uniform electron dense core of amorphous material and heavily stained; another type was small round vesicles with a non-uniform electron dense core of filamentous material and stained grey. These materials were released into the extracellular space by cytoplasmic exocytosis. CONCLUSIONS: Neoplastic myoepithelial cells have the ability to synthesize and secrete procollagen and precursor of elastin, thus forming collagenous fibers and elastic fibers in myxochondroid areas.

Adenoma, Pleomorphic↗

PubMed2000

[Studies on schedules for human rabies immunization].

OBJECTIVES: To study the feasibility of interferon (INF) plus an immunization schedule of two dose-two dose-one dose (2 - 2 - 1) of rabies vaccine and a simple 2 - 2 - 1 schedule, and to explore immune regulation mechanism of INF. METHODS: For an IFN plus 2 - 2 - 1 schedule, 5.0, 5.0 and 2.5 I.U. of primary hamster kidney cell rabies vaccine (PHKCV) were injected on the 1st, 7th and 14th day, respectively, and 0.2 million I.U. of IFN-alpha on the 1st day simultaneously. For a simple 2 - 2 - 1 schedule, only 5.0, 5.0 and 2.5 I.U. PHKCV were injected on the 1st, 7th and 14th day, respectively. And, for controls, a routine schedule recommended by WHO was used. RESULTS: On the 7th day after immunization, their geometric mean titer (GMT) of antibody was 1.71, 1.57 and 1.21 for the above three schedule groups, respectively; on the 14th day, 62.77, 58.79 and 28.96; on the 45th day, 76.64, 72.90 and 62.22. Conversion rate of antibody was 85.00%, 61.11% and 65.00%, respectively on the 7th day, and was 100.00% for all on the 14th day. Proportion of those with protective antibody level was 10.00%, 0.00% and 0.00%, respectively for the three schedule groups, on the 7th day; 100.00%, 100.00% and 95.00%, on the 14th day; and was 100.00% for all on the 45th day. Proportion of those with antibody titer more than 1:1 was 55.00%, 33.33% and 20.00%, respectively, on the 7th day. Adverse reaction rate was 0.00% - 55.00%, without significant difference between three schedule groups. CONCLUSIONS: Lower dose of IFN could enhance the effect of immune response to rabies vaccine. IFN plus 2 - 2 - 1 rabies vaccine schedule was better than that of simple 2 - 2 - 1 schedule, while the later was better than the routine schedule.

Adolescent↗