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Biomedical subjects

B Su

Publications and source records attributed to B Su.

At least 73 records · Page 4Linked to original sources
PubMed1998

[The effect of removable partial denture on the composition of bacteria on the apt-to-decay site of abutment teeth].

This study was aimed at the composition of plaques which were on the base teeth's carious sensitive sites, just after the insertion of the removable partial denture (RPD). The results showed that the ratios of bacterial detection in different teeth at the same period and those on the different sites of same teeth at different periods were not significantly different. There was a tendency that the detection ratio of the stomatococcus at the early period was higher than that of other bacteria, but at the middle period the ratios declined, and at the late period it was higher again. The detection ratio of the bacillus was on the contrary in the study. At the same time, the composition of the plaques changed significantly after the dentures had been used for 7, 14, and 21 days and 3 months. After 3 months, the ratios of the stomatococcus and the bacillas returned to their normal levels. The 3 main cariogenic bacteria were all detected in this study. The Streptococcus mutant was the dominant bacterium in the plaques and its ratio went up with the time duration. The ratio for the lower second molar was higher than that for the mandibular second premolar (P < 0.05). The detection ratios of the Actinomyces viscosus and lactobacillus were lower. In conclusion, after the insertion of RPD, the oral microbial ecosystem would be changed and the cariogenic bacteria began to implant on the surface of the base teeth. So RPD is a potential factor to cause the caries.

Actinomyces viscosus↗
PubMed1998

[Isolation and identification of N2-fixing strains of Bacillus in rice rhizosphere of the Yangtze River Valley].

Rice rhizosphere soil samples were colected from 10 sites of 7 provinces in the Yangzi River Valley, and from the soil samples 16 endospore-forming strains with ARA (Acetylene Reduction Activity) were isolated, the nitrogen fixing ability was tested by the method of 15N tracer and the atom 15N% excess are ranged from 0.0297% to 0.4714%. The strains were identified as Bacillus licheniformis, B. subtilis, B. azotoformans, B. cereus, B. pumilus, B. brevis, B. megaterium, B. firmu.

Acetylene↗
PubMed1997

Tissue factor positions and maintains the factor VIIa active site far above the membrane surface even in the absence of the factor VIIa Gla domain. A fluorescence resonance energy transfer study.

Coagulation factor VIIa (fVIIa), a soluble serine protease, exhibits full proteolytic activity only when bound to its cofactor, tissue factor (TF). Both proteins interact with membranes; TF is an integral membrane protein, while fVIIa binds reversibly to phospholipid surfaces via its Gla domain. In this study, we examine the extent to which the location of the fVIIa active site in the fVIIa.TF complex is determined by the fVIIa Gla domain. A fluorescein dye was covalently attached to the active site of fVIIa lacking the Gla domain (Gla domainless fVIIa, GD-fVIIa) via a tripeptide tether to yield fluorescein-D-Phe-Pro-Arg-GD-fVIIa (Fl-FPR-GD-fVIIa). The location of the active site of GD-fVIIa relative to the membrane surface was determined using fluorescence resonance energy transfer between the fluorescein dye in the active site of GD-fVIIa and octadecylrhodamine (OR) at the surface of phospholipid vesicles. As expected, no energy transfer was observed between Fl-FPR-GD-fVIIa and OR in vesicles composed of phosphatidylcholine/phosphatidylserine (PC/PS, 4:1) because the Gla domain is required for the binding of fVIIa to phospholipid. However, when Fl-FPR-GD-fVIIa was titrated with PC or PC/PS vesicles into which purified TF had been reconstituted, energy transfer was observed. Based on the dependence of fluorescence resonance energy transfer on OR density, the average distance of closest approach between fluorescein in the active site of Fl-FPR-GD-fVIIa.TF and OR at the vesicle surface was determined to be 78 A (kappa2 = (2)/(3)). Since this value is nearly the same as that obtained with intact Fl-FPR-fVIIa bound to TF, the presence or absence of the fVIIa Gla domain has only a small effect on the location of the active site in the fVIIa.TF complex. The extracellular domain of tissue factor therefore must be fairly rigid and fixed relative to the surface to position and maintain the fVIIa active site far above the membrane even in the absence of the fVIIa Gla domain.

Binding Sites↗
PubMed1997

Dynamic regulation of c-Jun N-terminal kinase activity in mouse brain by environmental stimuli.

Activation of the recently identified c-Jun N-terminal kinases (JNKs) typically results in programmed cell death (apoptosis) in neurons and other cell types grown in culture. However, the effects of JNK activation in the central nervous system in vivo are unknown. At baseline, JNK activity in mice was on average 17-fold higher in brain than in peripheral organs, whereas JNK protein levels were similar. In brain, JNK was expressed primarily in neurons. Restraining mice or allowing them to explore a novel environment rapidly increased JNK activity 3- to 15-fold in various brain regions, but these manipulations did not increase brain activity of the extracellular signal-regulated kinase. Because noninvasive environmental stimuli that do not induce neurodegeneration elicited prominent increases in JNK activity in the brain, we conclude that acute activation of the JNK cascade in central nervous system neurons does not induce neuronal apoptosis in vivo. In contrast, the high baseline activity of JNK in the brain and the activation of the JNK cascade by environmental stimuli suggest that this kinase may play an important physiological role in neuronal function.

Animals↗
PubMed1997

[Extraction and sequencing of trace DNA from cornu Cervi pantotrichum].

The trace DNA extraction method was used to extract DNA from the blood, hair, Cornu cervi pantotrichum, hairy antler of the sika deer, Cervus nippon, and penis of Bulbalus bublis and Asinus vulgaris. A 307 bp fragment of mitochondrial DNA cytochrome b gene was amplified with primers L14841 and H15149 for these extractions. The purified PCR products were sequenced by the dideoxy method. DNA sequence obtained from the Cornu cervi pantotrichum is the same as that obtained from the fresh blood and hair of the sika deer, but the sequence of the so-called hairy antler is quite different, implying that it is not from the sika deer. In addition, the phylogenetic relationships among different species are congruent with the traditional known phylogeny.

Animals↗
PubMed1997

[A survey on mother's nutritional knowledge-attitude on the feeding of young child in Guangdong province].

A survey on mother's nutrition knowledge-attitude on the feeding of young child was conducted in Guangdong province in 1995 among 414 mothers of 0 to 18 months old children. The results showed that the nutritional knowledge-attitude level of the mothers was low in both city and township. Only 51% of them had qualified level. The level of general nutritional concepts and the nutritional knowledge-attitude during weaning period were significantly lower than that of breastfeeding and follow-weaning. It suggests that the promotion of nutritional education in the feeding of young children is urgent in Guangdong province especially in township and rural area. It is necessary to focus on the improvement of nutritional knoweledge in weaning period and general nutrition concepts.

Breast Feeding↗
PubMed1997

Factor VIIa-tissue factor: functional importance of protein-membrane interactions.

The first enzyme in the blood clotting cascade consists of two distinct protein subunits: a catalytic subunit (factor VIIa; FVIIa) and an essential regulatory subunit (tissue factor; TF). FVIIa is a soluble plasma protease, while TF is a cell-surface, integral-membrane protein. The recently reported X-ray crystal structure of the complex of FVIIa and the isolated extracellular domain of TF has provided important insights into the protein-protein interactions that bind these two subunits together (1). Equally important in the functioning of the TF-FVIIa complex, but much less well understood, are a series of protein-phospholipid interactions involving TF, FVIIa, and the natural substrates of this enzyme, as well as protein-protein interactions important in substrate recognition by TF-FVIIa. Here we review recent studies on the membrane organization and role of protein-phospholipid interactions in the function of TF-FVIIa, the enzyme that triggers blood clotting in hemostasis and thrombosis.

Crystallography, X-Ray↗
PubMed1997

[Genetic diversity and phylogenetic relationships among Chinese Macacas based on protein electrophoresis].

In this paper, using protein electrophoresis method, we studied proteinpolymorphism and genetic divergence of 5 species in Genus Macaca: M. mulatta, M. arctoides, M. assamensis, M. thibetana, M. fascicularis. A total of 30 genetic loci were analyzed for 29 individuals, including 4 Nycticebus pygmaeus as outgroup. For the 19 M. mulatta, 9 loci were found to be polymorphic. Accordingly, the percentage of polymorphic loci, P = 0.3; the mean number of alleles, A = 1.4, and the mean heterozygosity, H = 0.1045, indicating a rather high level of genetic diversity in this species. Furthermore, 10 loci showed polymorphic among the 5 species, which can be used as information loci for phylogenetic reconstruction. Three programs (conml, neighbor, fitch) in PHYLIP 3.5 c were chosen to construct phylogenetic trees. All of the three trees show support a close relationship between M. mulatta and M. fascicularis. However, two trees have the same topology, suggesting that M. arctoides belongs to an independent species group, while M. assamensis and M. thibetana are closely related and belong to another species group, and the other tree gives a different topology which implies that M. arctoides, M. assamensis and M. thibetana belong to one species group.

Animals↗
PubMed1997

Differentiation of human gastric adenocarcinoma cell line MGc80-3 induced by verbascoside.

Verbascoside is a natural antioxidant extracted from Pedicularis striata Pall (Jueyehesen). After being treated with 20 mumol/l verbascoside, the growth curve and mitotic index of human gastric adenocarcinoma MGc80-3 cells decreased remarkably, cell doubling time was delayed, the cellular growth inhibitory rate amounted to 53.2%, cell surface charge assayed by cell electrophoresis obviously changed, the electrophoresis rate dropped from 3.51 microns/s/v/cm to 2.74, i.e., the percent of retardation reached 28.4%. There was a 75% decrease of the tumorigenicity for the treated cells compared with the untreated cells inoculated subcutaneously in BALB/C nude mice. Scanning electron microscopy revealed that the microvilli on the surface of treated cells had been reduced obviously. It confirmed that verbascoside, similar to DMSO, could reverse MGc80-3 cells' malignant phenotypic characteristics and induced redifferentiation of MGc80-3 cells.

Adenocarcinoma↗
PubMed1997

[Genetic divergence of Cordyceps sinensis as estimated by random amplified polymorphic DNA analysis].

Random amplified polymorphic DNA(RAPD) has been used in analyzing 13 winter worm, summer grasses (Cordyceps sinensis [Berk.], Sacc.) from 5 areas in Qingzang plateau. For 19 arbitrary primers, each individual showed about 65 RAPD markers. The genetic distances among those 13 winter worm, summer grasses were correlated to their geographic distances. Molecular phylogenetic tree constructed by UPGMA and NJ suggested that 13 winter worm, summer grasses could be divided into 3 clusters: east cluster, north cluster and middle cluster, in consistence with their origins and genetic divergence among different clusters. Furthermore, our results implied that the RAPD markers of winter worm, summer grasses showed a geographic specificity and could be a better genetic marker in studying genetic diversity and phylogeny of winter worm, summer grasses.

Genetic Variation↗
PubMed1996

The tumor promoter arsenite stimulates AP-1 activity by inhibiting a JNK phosphatase.

Trivalent arsenic (As3+) is highly carcinogenic, but devoid of known mutagenic activity. Therefore, it is likely to act as a tumor promoter. To understand the molecular basis for the tumor-promoting activity of As3+, we examined its effect on transcription factor AP-1, whose activity is stimulated by several other tumor promoters. We found that As3+, but not As5+, which is toxic but not carcinogenic, is a potent stimulator of AP-1 transcriptional activity and an efficient inducer of c-fos and c-jun gene expression. Induction of c-jun and c-fos transcription by As3+ correlates with activation of Jun kinases (JNKs) and p38/Mpk2, which phosphorylate transcription factors that activate these immediate early genes. No effect on ERK activity was observed. As5+, on the other hand, had a negligible effect on JNK or p38/Mpk2 activity. Biochemical analysis and co-transfection experiments strongly suggest that the primary mechanism by which As3+ stimulates JNK activity involves the inhibition of a constitutive dual-specificity JNK phosphatase. This phosphatase activity appears to be responsible for maintaining low basal JNK activity in non-stimulated cells and its inhibition may lead to tumor promotion through induction of proto-oncogenes such as c-jun and c-fos, and stimulation of AP-1 activity. The same phosphatase may also regulate p38/Mpk2 activity.

Arsenites↗
PubMed1996

Constitutively activated JNK is associated with HTLV-1 mediated tumorigenesis.

Human T cell leukemia virus type I (HTLV-1) is the etiologic agent of adult T-cell leukemia (ATL) and HTLV-1 associated myelopathy, also called tropical spastic paraparesis (HAM/TSP). Both clinical and in vitro evidence have demonstrated that the virus or its transactivator Tax, are transforming. However, transformation appears to require additional, as yet poorly characterized, genetic changes in infected cells. JNK is a recently characterized member of the MAP kinase family. Its signaling cascade is distinct from other members and has been demonstrated to play an important role in T-cell activation, at least partially through its downstream targets, c-jun and ATF-2. Here we demonstrate constitutive activation of the JNK cascade in human lymphocytes transformed in vitro by HTLV-1 and also in Tax transformed murine fibroblasts. Such activation is not induced by Tax expression alone, and occurs only when infected lymphocytes become IL-2 independent or immortalized. Constitutive JNK activation was also found in leukocytes isolated from ATL patients. The acquisition of constitutive JNK activation may represent an important later event in HTLV-1 tumorigenesis.

Animals↗
PubMed1996

Mitogen-activated protein kinase cascades and regulation of gene expression.

Mitogen-activated protein kinases (MAPKs) are a group of serine/threonine specific, proline directed, protein kinases which are activated by a wide spectrum of extracellular stimuli. MAPK activation is achieved through kinase cascades, which include a MAPK kinase (MAPKK or MEK) and a MAPKK/MEK kinase (MAPKKK/MEKK). These cascades serve as information relays, connecting cell-surface receptors to specific transcription factors and other regulatory proteins, thus allowing extracellular signals to regulate the expression of specific genes. Genetic and biochemical analyses have revealed many tiers in the regulation of the activities of MAPKs, as well as different routes that lead to the activation of an individual MAPK. An emerging topic of great interest is the basis for specificity in the activation of individual MAPKs and their ability to recognize their substrates.

Animals↗
PubMed1996

Repair of dGMP hydroxyl radical adducts by verbascoside via electron transfer: a pulse radiolysis study.

The repair activity of verbascoside (VER), isolated from Pedicularis spicata, towards the oxidizing hydroxyl radical adduct of dGMP and its reaction mechanism were studied using pulse radiolysis. Upon pulse radiolysis of nitrous oxide saturated aqueous solution of 2'-deoxyguanosine-5'-monophosphate (dGMP) and VER, it was found that the transient absorption spectrum of the hydroxyl adduct of dGMP decays with the formation of that of the phenoxyl radical of VER, several tens of microseconds after the electron pulse. From the formation kinetics of the phenoxyl radical of VER, the rate constant of the repair reaction was determined to be 1.12 x 10(9) dm(3) mol(-1) s(-1).

Antioxidants↗
PubMed1996

The Ras-JNK pathway is involved in shear-induced gene expression.

Hemodynamic forces play a key role in inducing atherosclerosis-implicated gene expression in vascular endothelial cells. To elucidate the signal transduction pathway leading to such gene expression, we studied the effects of fluid shearing on the activities of upstream signaling molecules. Fluid shearing (shear stress, 12 dynes/cm2 [1 dyne = 10(-5)N]) induced a transient and rapid activation of p21ras and preferentially activated c-Jun NH2 terminal kinases (JNK1 and JNK2) over extracellular signal-regulated kinases (ERK-1 and ERK-2). Cotransfection of RasN17, a dominant negative mutant of Ha-Ras, attenuated the shear-activated JNK and luciferase reporters driven by 12-O-tetradecanoylphorbol-13-acetate-responsive elements. JNK(K-R) and MEKK(K-M), the respective catalytically inactive mutants of JNK1 and MEKK, also partially inhibited the shear-induced luciferase reporters. In contrast, Raf301, ERK(K71R), and ERK(K52R), the dominant negative mutants of Raf-1, ERK-1, and ERK-2, respectively, had little effect on the activities of these reporters. The activation of JNK was also correlated with increased c-Jun transcriptional activity, which was attenuated by a negative mutant of Son of sevenless. Thus, mechanical stimulation exerted by fluid shearing activates primarily the Ras-MEKK-JNK pathway in inducing endothelial gene expression.

Animals↗