Biomedical subjects

S F Yang

Publications and source records attributed to S F Yang.

At least 19 recordsLinked to original sources

PubMed2007

Altered p-JAK1 expression is associated with estrogen receptor status in breast infiltrating ductal carcinoma.

The mammalian Janus kinase (JAK) family consists of four members, namely JAK1, JAK2, JAK3 and TYK2, which play a critical role in cytokine/growth factor signaling and is increasingly associated with human cancers. Aberrant activation of these non-receptor tyrosine kinases may contribute to carcinogenesis. Herein, we focused on exploring the potential role of p-JAK1 in breast cancer. The expression profiles of p-JAK1 were analyzed in 68 pairs of cancer and non-cancer breast tissues from the same infiltrating ductal carcinoma case by using immunoblotting technique. The results obtained were further correlated with clinicopathological characteristics. Intriguingly, p-JAK1 expression was decreased in 55.9% of breast cancer tissues as compared to the matched non-cancer tissues. Further immunohistochemistry study showed an intense p-JAK1 staining predominantly in adjacent normal breast tissues but not the matched cancer lesions. Decreased p-JAK1 expression in breast cancer tissues was significantly correlated with positive estrogen receptor (ER) status and increased tumor size (p=0.010 and 0.009). We also found that p-JAK1 expression was high in ERalpha-negative breast cancer cell lines but was low in ERalpha-positive breast cell lines. Transfection of ERalpha-positive MCF-7 cells with an ERalpha-specific siRNA upregulated the expression of p-JAK1. In summary, our results indicated that an altered p-JAK1 expression might be involved in the development of breast infiltrating ductal carcinoma in an ERalpha-related manner.

Breast Neoplasms↗

PubMed2006

Influence of loosely bound extracellular polymeric substances (EPS) on the flocculation, sedimentation and dewaterability of activated sludge.

Laboratory experiments on the activated sludge (AS) process were carried out to investigate the influence of microbial extracellular polymeric substances (EPS), including loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS), on biomass flocculation, sludge settlement and dewaterability. The heat EPS extraction method was modified to include a mild step and a harsh step for extracting the LB-EPS and TB-EPS, respectively, from the sludge suspension. Six lab-scale AS reactors were used to grow AS with different carbon sources of glucose and sodium acetate, and different sludge retention times (SRTs) of 5, 10 and 20 days. The variation in the bioreactor condition produced sludge with different abundances of EPS and different flocculation and separation characteristics. The sludge that was fed on glucose had more EPS than the sludge that was fed on acetate. For any of the feeding substrates, the sludge had a nearly consistent TB-EPS value regardless of the SRT, and an LB-EPS content that decreased with the SRT. The acetate-fed sludge performed better than the glucose-fed sludge in terms of bioflocculation, sludge sedimentation and compression, and sludge dewaterability. The sludge flocculation and separation improved considerably as the SRT lengthened. The results demonstrate that the LB-EPS had a negative effect on bioflocculation and sludge-water separation. The parameters for the performance of sludge-water separation were much more closely correlated with the amount of LB-EPS than with the amount of TB-EPS. It is argued that although EPS is essential to sludge floc formation, excessive EPS in the form of LB-EPS could weaken cell attachment and the floc structure, resulting in poor bioflocculation, greater cell erosion and retarded sludge-water separation.

Bacteria↗

PubMed2006

Father of 1-MCP.

Explore the source record for details and available documents.

Botany↗

PubMed2004

Removal of dissolved copper(II) and zinc(II) by aerobic granular sludge.

This study investigated the adsorption kinetics of dissolved copper(II) and zinc(II) by aerobic granular sludge. Two series of batch experiments were conducted at different initial copper(II), zinc(II) concentrations (Co) and initial granule concentrations (Xo). Results showed that the biosorption kinetics of individual copper(II) and zinc(II) by aerobic granules were closely related to Co and Xo. The maximum biosorption capacity of individual copper(II) and zinc(II) by aerobic granules was 246.1 mg g(-1) and 180 mg g(-1), respectively. In order to theoretically interpret the results obtained, two kinetic models previously developed for biosorption were employed and compared in this study. It was found that the model proposed by Liu et al. (2003) could fit the experimental data very well, but the second-order model failed to fit the data in some cases. It appears that aerobic granules would be potential biosorbent with high efficiency for the removal of dissolved copper(II) and zinc(II) from wastewater.

Adsorption↗

PubMed2001

The catalytic mechanism of 1-aminocyclopropane-1-carboxylic acid oxidase.

It has been proposed that 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase catalyzes the oxidation of ACC to ethylene via N-hydroxyl-ACC as an intermediate. However, due to its chemical instability the putative intermediate has never been isolated. Here, we have shown that a purified recombinant ACC oxidase can utilize alpha-aminoisobutyric acid (AIB), an analog of ACC, as an alternative substrate, converting AIB into CO2, acetone, and ammonia. We chemically synthesized the putative intermediate compound, N-hydroxyl-AIB (HAIB), and tested whether it serves as an intermediate in the oxidation of AIB. When [1-(14)C]AIB was incubated with ACC oxidase in the presence of excess unlabeled HAIB as a trap, no labeled HAIB was detected. By comparing the acetone production rates employing HAIB and AIB as substrates, the conversion of HAIB to acetone was found to be much slower than that of using AIB as substrate. Based on these observations, we conclude that ACC oxidase does not catalyze via the N-hydroxylation of its amino acid substrate. ACC oxidase also catalyzes the oxidation of other amino acids, with preference for the D-enantiomers, indicating a stereoselectivity of the enzyme.

Acetone↗

PubMed2001

Alternations in quantities and activities of erythrocyte cytosolic carbonic anhydrase isoenzymes in glucose-6-phosphate dehydrogenase-deficient individuals.

BACKGROUND: This study was designed to evaluate the quantitative and activity alterations of cytosolic carbonic anhydrase (CA) isoenzymes in the erythrocytes of glucose-6-phosphate dehydrogenase (G6PD)-deficient individuals. METHODS: Western Blot and CA esterase activity analysis were employed to measure cytosolic erythrocyte CA isoenzymes. RESULTS: The total CA activities were analyzed from erythrocytes of 30 healthy and 30 G6PD-deficient individuals. The mean values with standard error (SE) were 22.9+/-1.69 U/gHb and 27.2+/-2.1 U/gHb (P<0.01), respectively. The ratio of CAI/CAII of G6PD-deficient individuals (1.28+/-0.06) was significantly lower than that of the normal subjects (3.79+/-0.18) (P<0.001). Furthermore, the concentration of CAIII in G6PD-deficient individuals was significantly lower than that of the normal subjects (P<0.001) and there were significant correlations between the concentration of CAI, CAII, CAIII, and ratio of CAI/CAII, and the activity concentration of G6PD. CONCLUSIONS: Different carbonic anhydrase isoenzymes may serve different roles in the G6PD-deficient erythrocyte. CAI could be used as an indicator for hemolytic anemia. CAII is able to compensate for the functions of CAI and increased expression of CAII will promote oxidative damage. CAIII can provide the G6PD-deficient persons with some extent of protection against oxidative damage.

Adult↗

PubMed2001

Regulation of matrix metalloproteinase-2 production by cytokines and pharmacological agents in human pulp cell cultures.

Type IV matrix metalloproteinases (MMPs) are members of the family of MMPs and are thought to play an important role in degradation of extracellular components. Human pulp cells can secrete and produce these enzymes. Recent evidence shows that MMPs may play a role in pulpal inflammation. To date little is known regarding the regulation of MMPs in human pulp cell cultures. The purpose of this study was to determine the effects of cytokines (interleukin-1 and transforming growth factor-beta (TGF-beta), protein synthesis inhibitor cycloheximide (CD), and protein kinase C inhibitors (H7 and Go6976) on the secretion and production of MMPs by human pulp cell cultures using gelatin zymography. The main gelatinase secreted by human pulp cells migrated at 72 kDa and represented MMP-2. Minor gelatinolytic bands were also observed at 92 kDa regions that correspond to MMP-9. After an 8-day culture period TGF-beta, CD, H7, and Go6976 were found to depress MMP-2 production. The inhibition decreased in an order of CD > H7 > TGF-beta > Go6976. IL-1 was found to elevate MMP-2 production. Human pulp cells, however treated with either cytokines or pharmacological agents had no effect on the pattern of MMP-9 produced or secreted in either cell extracts or conditioned medium fractions. These observations suggest that the cytokines and pharmacological agents can regulate MMP-2 produced by human pulp cells. Inflammatory cytokines stimulate the production of elevated levels of MMP-2 and MMP-2 might play a role in pulpal inflammation. In addition agents that target protein synthesis or the protein kinase C pathway in human pulp cells inhibit MMP-2 production, and such inhibition may contribute to the pathogenesis of pulpal inflammation. Such inhibition might contribute to therapeutic efficacy.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed2001

Differential expression of 1-aminocyclopropane-1-carboxylate synthase genes during orchid flower senescence induced by the protein phosphatase inhibitor okadaic acid.

Applying 10 pmol of okadaic acid (OA), a specific inhibitor of type 1 or type 2A serine/threonine protein phosphatases, to the orchid (Phalaenopsis species) stigma induced a dramatic increase in ethylene production and an accelerated senescence of the whole flower. Aminoethoxyvinylglycine or silver thiosulfate, inhibitors of ethylene biosynthesis or action, respectively, effectively inhibited the OA-induced ethylene production and retarded flower senescence, suggesting that the protein phosphatase inhibitor induced orchid flower senescence through an ethylene-mediated signaling pathway. OA treatment induced a differential expression pattern for the 1-aminocyclopropane-1-carboxylic acid synthase multigene family. Accumulation of Phal-ACS1 transcript in the stigma, labelum, and ovary induced by OA were higher than those induced by pollination as determined by "semiquantitative" reverse transcriptase-polymerase chain reaction. In contrast, the transcript levels of Phal-ACS2 and Phal-ACS3 induced by OA were much lower than those induced by pollination. Staurosporine, a protein kinase inhibitor, on the other hand, inhibited the OA-induced Phal-ACS1 expression in the stigma and delayed flower senescence. Our results suggest that a hyper-phosphorylation status of an unidentified protein(s) is involved in up-regulating the expression of Phal-ACS1 gene resulting in increased ethylene production and accelerated the senescence process of orchid flower.

Enzyme Inhibitors↗

PubMed2001

Signaling events in the hypoxic induction of alcohol dehydrogenase gene in Arabidopsis.

Expression of the alcohol dehydrogenase gene (ADH) of Arabidopsis is induced during hypoxia. Because many plants increase their ethylene production in response to hypoxic stress, we examined in this report whether ethylene is involved in the hypoxic induction of ADH in Arabidopsis. We found that the hypoxic induction of ADH can be partially inhibited by aminooxy acetic acid, an inhibitor of ethylene biosynthesis. This partial inhibition can be reversed by the addition of 1-aminocyclopropane-1-carboxylic acid, a direct precursor of ethylene. In addition, the hypoxic induction of the ADH gene is also reduced in etr1-1 and ein2-1, two ethylene insensitive mutants in ethylene-signaling pathways, whereas the addition of exogenous ethylene or an increase in cellular ethylene alone does not induce ADH under normoxic conditions. Kinetic analyses of ADH mRNA accumulation indicated that an ethylene signal is required for the induction of ADH during later stages of hypoxia. Therefore, we conclude that ethylene is needed, but not sufficient for, the induction of ADH in Arabidopsis during hypoxia.

Alcohol Dehydrogenase↗

PubMed2001

Central norepinephrine pathways are involved in cardiovascular response to intracerebroventricular substance P.

AIM: To study the role of norepinephrine system in the cardiovascular response to intracerebroventricular substance P (SP) in rabbit. METHODS: SP was given intracerebroventricularly in anesthetized rabbits pretreated with the catecholaminergic neurotoxin, 6-hydroxydopamine (6-OHDA). The density and affinity of SP receptors on synaptosomal membranes of the hypothalamus and the ventral medulla of rabbits were determined by [125I]SP receptor assay. Arterial blood pressure and heart rate were recorded. RESULTS: Intracerebroventricular (icv) pretreatment of rabbits with 6-OHDA, reduced norepinephrine in the hypothalamus (by 86.7 %) and in the ventral medulla (by 77.0 %) respectively. The pressor response and tachycardia of these rabbits to icv SP (3.55 nmol . kg-1) were attenuated. The density and the affinity of SP receptors in the hypothalamus and the ventral medulla of 6-OHDA-lesioned rabbits were decreased. The Bmax (pmol . g-1 protein) of SP receptors in hypothalamus and the ventral medulla are 108 +/- 5, 35.9 +/- 2.2 in control group, and 42 +/- 18, 20 +/- 5 in 6-OHDA-lesioned rabbits, respectively. Kd (nmol . L-1) of SP receptors in the two regions are 0.015 +/- 0.004, 0.014 +/- 0.006 in control group and 0.029 +/- 0.001, 0.015 +/- 0.003 in 6-OHDA group. There is a significant difference of Bmax (P < 0.01) and Kd (P < 0.01, P < 0.05) in both regions between 6-OHDA groups and control groups. CONCLUSION: The results suggested that central norepinephrine pathways are involved in the cardiovascular response to icv SP.

Animals↗

PubMed2001

Protective effect and mechanism of Ginkgo biloba leaf extracts for Parkinson disease induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.

AIM: To observe the effects of extracts of Ginkgo biloba leaves (EGb) on the Parkinson disease (PD) models induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and its ion 1-methyl-4-phenylpyridinium (MPP+). METHODS: MPTP was microinjected into substantia nigra of rats to induce a behavior change of rotation. EGb (ip, 50 or 100 mg.kg(1 . d-1) was pretreated consecutively for 19 d before MPTP administered and 1 d after MPTP administered. The contents of malondialdehyde (MDA), superoxide dismutase (SOD), and dopamine (DA) in substantia nigra of model rats were determined. Apoptosis of PC12 cells was induced by MPP+, and the protective effect of EGb (25, 50, and 100 mg/L) was also observed. The cells of apoptosis were observed under a microscope and counted under a fluoroscope after stained with AO/EB. RESULTS: EGb (100 mg . kg-1 . d-1) decreased the duration and frequency of the rotation of rats (P < 0.05, n = 10 ) while EGb (50 or 100 mg/L)inhibited the decreases of DA and SOD and the increase of MDA induced by MPTP, (P < 0.05 or P < 0.01, n = 10). MPP+ (10 micromol/L) induced the apoptosis of PC12 cells, and EGb (50 or 100 mg/L) prevented cells from apoptosis at 6 h, 12 h, and 24 h (P < 0.05 or P < 0.01, n = 3). CONCLUSION: EGb possesses protective effect on the PD models in vivo and in vitro. The anti-oxidation and anti-apoptosis may be one of the mechanisms underlying the neuroprotective effect of EGb.

Animals↗

PubMed2000

An accident with a Gates Glidden drill in endodontic practice.

An unusual accident in clinical endodontic practice is described. The Gates Glidden drill is currently being used for establishing straight-line access in endodontic practice (1). One potential hazard in using the Gates Glidden drill is that it can separate within the canal (2). This article reports an accident involving a Gates Glidden drill separating in the elbow of a dentist during endodontic practice and to discuss the safety of using a Gates Glidden drill.

Accidents, Occupational↗

PubMed1999

Microleakage between endodontic temporary restorative materials placed at different times.

Occlusal endodontic access preparations are occasionally made in teeth without removing the original restoration. However, microleakage between restorative materials that are placed at different times has not been extensively studied. Therefore, our objective was to compare microleakage at three areas: between an access opening restorative material and the cavity wall; between an additional material placed later to patch a secondary opening in the first restorative material and the original restorative material itself; and between the secondarily placed material and the cavity wall. Standard endodontic access preparations were made in 120 noncarious, nonrestored crowns of extracted human molars. These teeth were divided into six experimental groups. Another four molars were controls. The endodontic access cavities were restored with either IRM or amalgam as the primary restorative material. After 14 days, half of the primary restorations was removed, and this defect was filled with a secondary restorative material: IRM, Caviton, or a double seal of Caviton and IRM. Microleakage was measured linearly as the extent of basic fuchsin dye penetration under a stereomicroscope after thermal cycling (5 degrees and 55 degrees C for 100 cycles) and tooth sectioning. Wilcoxon signed-rank test was used for statistical analysis. Results indicated significantly less microleakage between primary and secondary restorative materials placed at different times than microleakage between primary temporary restorative materials and the access cavity wall, regardless of the type of primary restorative material used (IRM or amalgam).

Calcium Sulfate↗

PubMed1999

Identification of two chilling-regulated 1-aminocyclopropane-1-carboxylate synthase genes from citrus (Citrus sinensis Osbeck) fruit.

Diurnal change in the temperature below or above 12.5 degrees C hastens the degreening of citrus peel and elicits the phytohormone ethylene production in citrus fruit. Ethylene triggers the degradation of chlorophyll and synthesis of carotenoids in citrus peel. To investigate if ethylene is required for the degreening of citrus peel elicited by low temperatures, we studied the chilling-regulated gene expression of ACC synthase, one of the key enzymes catalyzing ethylene biosynthesis. We isolated and characterized a chilling-inducible 1-aminocyclopropane-1-carboxylate synthase (ACC synthase) gene, CS-ACS1, and a chilling-repressible gene, CS-ACS2, from citrus peel. The CS-ACS1 transcript 1.7 kb in length encodes a polypeptide of 483 amino acids (Mr 54,115, pI 6.63), whereas the CS-ACS2 transcript of 1.8 kb encodes a polypeptide of 477 amino acids (Mr 53,291, pI 6.72). Both genes showed a rapid but transient induction (within 2.4 h) of transcripts upon rewarming after the chilling (4 degrees C) treatment. After 24 h of incubation at room temperature, CS-ACS1 mRNA diminished to an undetectable level, whereas the CS-ACS2 mRNA regained its basal level of expression attained prior to the chilling treatment. Chilling-induced ethylene production and ACC accumulation were also observed upon rewarming. Both genes were also induced by the wound stress (excision). The protein synthesis inhibitor cycloheximide super-enhances the accumulation of both ACS transcripts at room temperature. Molecular analysis of the 3.3 kb genomic DNA of CS-ACS1 revealed that this gene consists of three introns and four exons. The intron 3 is exceptionally large ( 1.2 kb) and shares significant homology with mitochondrial DNA, supporting the intron-late theory.

Amino Acid Sequence↗

PubMed1999

A UV-light activated cinnamic acid isomer regulates plant growth and gravitropism via an ethylene receptor-independent pathway.

Naturally occurring cinnamic acids (CA) exist in both trans- and cis-isoforms. UV-light irradiation of trans-CA is able to produce cis-CA. cis-CA was found to possess auxin-like activity before. In contrast, the vapor of cis-CA induced an epinastic response in tomato plants just as ethylene does. Given the existence of a double bond in and the gaseous nature of cis-CA, we suspected that cis-CA might also function as an ethylene-like compound. To distinguish between these possibilities, we selected an ethylene perception-deficient tomato plant, Never-ripe (Nr), and an ethylene biosynthesis-deficient tomato plant, A11. Not only did the vapor of cis-CA fail to trigger A11 tomato fruit ripening but it also delayed the ripening of banana fruit. Moreover, the vapor of cis-CA induced epinasty and the 'triple response' in both the wild type and Nr tomato plants, indicating that the vapor of cis-CA does not act via an ethylene receptor-dependent pathway. Furthermore, the vapor of cis-CA inhibited the negative gravitropic response of stems of both etiolated Nr seedlings and young plants, whereas ethylene had little effect on the negative gravitropism of the Nr plants. These results support the conclusion that the action sites of the vapor of cis-CA and ethylene are fundamentally different.

Arabidopsis↗

PubMed1999

The multiple roles of conserved arginine 286 of 1-aminocyclopropane-1-carboxylate synthase. Coenzyme binding, substrate binding, and beyond.

A pyridoxal 5'-phosphate (PLP)-dependent enzyme, 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (S-adenosyl-L-Met methylthioadenosine-lyase, EC 4.4.1.14), catalyzes the conversion of S-adenosyl-L-methionine (AdoMet) to ACC. A tomato ACC synthase isozyme (LE-ACS2) with a deletion of 46 amino acids at the C terminus was chosen as the control enzyme for the study of the function of R286 in ACC synthase. R286 of the tomato ACC synthase was mutated to a leucine via site-directed mutagenesis. The ACC synthase mutant R286L was purified using a simplified two-step purification protocol. Circular dichroism (CD) analysis indicated that the overall three-dimensional structure of the mutant was indistinguishable from that of the control enzyme. Fluorescence spectroscopy revealed that the binding affinity of R286L ACC synthase for its cofactor PLP was reduced 20- to 25-fold compared with control. Kinetic analysis of R286L showed that this mutant ACC synthase had a significantly reduced turnover number (k(cat)) of 8.2 x 10(-3) s(-1) and an increased K(m) of 730 microM for AdoMet, leading to an 8,000-fold decrease in overall catalytic efficiency compared with the control enzyme. Thus, R286 of tomato ACC synthase is involved in binding both PLP and AdoMet.

Amino Acid Sequence↗

PubMed1998

The promoter of LE-ACS7, an early flooding-induced 1-aminocyclopropane-1-carboxylate synthase gene of the tomato, is tagged by a Sol3 transposon.

Many terrestrial plants respond to flooding with enhanced ethylene production. The roots of flooded plants produce 1-aminocyclopropane-1-carboxylic acid (ACC), which is transported from the root to the shoot, where it is converted to ethylene. In the roots, ACC is synthesized by ACC synthase, which is encoded by a multigene family. Previously, we identified two ACC synthase genes of tomato that are involved in flooding-induced ethylene production. Here, we report the cloning of LE-ACS7, a new tomato ACC synthase with a role early during flooding but also in the early wound response of leaves. The promoter of LE-ACS7 is tagged by a Sol3 transposon. A Sol3 transposon is also present in the tomato polygalacturonase promoter to which it conferred regulatory elements. Thus, Sol3 transposons may affect the regulation of LE-ACS7 and may be involved in the communication between the root and the shoot of waterlogged tomato plants.

Amino Acid Sequence↗

PubMed1998

Comparison of hemodynamics and recovery of sevoflurane and isoflurane anesthesia in Chinese adult patients.

BACKGROUND: The new inhalational anesthetic sevoflurane would be expected to provide a rapid emergence from anesthesia due to its low blood/gas partition coefficient. In this study, we compared the hemodynamic effects, speed and quality of emergence, in ASA class I-II Chinese adult surgical patients receiving either sevoflurane or isoflurane anesthesia. METHODS: Eighty adult Chinese patients, ASA class I-II, scheduled for elective gynecological or general surgical procedures, were randomized to receive sevoflurane (n = 40) or isoflurane (n = 40) anesthesia. Ventilation is controlled via endotracheal intubation with anesthesia facilitated by either agent at anesthetic concentration of 1-1.5 MAC under the fresh gas flow 2 L/min. Heart rate, arterial blood pressure, temperature, SpO2 and end-tidal CO2 were continuously monitored. Any adverse effect such as airway irritation, nausea or vomiting was recorded during induction and emergence from anesthesia. The emergence time was assessed by various questionales for orientation during recovery. In the post-anesthetic recovery period, pain was monitored and managed by objective pain discomfort scale for analgesic supplements. Complaints of nausea and vomiting were recorded and followed up by a research nurse who visited the patient within 24 h following surgery. RESULTS: The extent of exposure to anesthetic (MAC x hours) was similar in both groups. Sevoflurane and isoflurane caused similar alterations in systolic and diastolic arterial pressure during maintenance. After surgical incision, the heart rate accelerated more in patients receiving isoflurane (p < 0.05). During emergence, time of response to command was significantly shorter in patients receiving sevoflurane than patients receiving isoflurane (5.6 +/- 0.4 min versus 15.2 +/- 3.0 min, p < 0.001). Side effects such as nausea and vomiting were comparable in both groups. CONCLUSIONS: Compared with isoflurane, sevoflurane anesthesia had the clinical advantages of maintaining stable hemodynamics and rapid recovery in Chinese adult patients.

Adult↗