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Biomedical subjects

Y Su

Publications and source records attributed to Y Su.

At least 19 recordsLinked to original sources
PubMed2003

Two variants of zebrafish p100 are expressed during embryogenesis and regulated by Nodal signaling.

Human p100 protein was first identified as a transcriptional coactivator of Epstein-Barr virus nuclear antigen 2, and has been shown to be a coactivator of other cellular transactivators. Its roles in development of vertebrate embryos, however, have not been reported. We have identified a zebrafish ortholog of the human p100 coactivator. The zebrafish p100 transcript is processed to two alternative variants, long and short forms, referred to as p100L and p100S, respectively. Both GFP-p100L and GFP-p100S fusion proteins are located in the cytoplasm of transfected culture cells and microinjected embryonic cells. Analysis of transcripts with Northern blots revealed the presence of p100L and lower amounts of p100S mRNAs from the one-cell stage throughout the life cycle. Whole-mount in situ hybridization shows that p100L and p100S share the same spatiotemporal expression pattern. Their zygotic expression is initially restricted to axial mesoderm precursors during gastrulation, and then spreads over other tissues during segmentation, and finally is constrained to some internal organs at day 5. We also find that Nodal signaling is essential for the zygotic expression of p100. These studies pave the way to understanding in depth the role of p100 during vertebrate embryogenesis.

Alternative Splicing↗
PubMed2001

Amphiphysin is necessary for organization of the excitation-contraction coupling machinery of muscles, but not for synaptic vesicle endocytosis in Drosophila.

Amphiphysins 1 and 2 are enriched in the mammalian brain and are proposed to recruit dynamin to sites of endocytosis. Shorter amphiphysin 2 splice variants are also found ubiquitously, with an enrichment in skeletal muscle. At the Drosophila larval neuromuscular junction, amphiphysin is localized postsynaptically and amphiphysin mutants have no major defects in neurotransmission; they are also viable, but flightless. Like mammalian amphiphysin 2 in muscles, Drosophila amphiphysin does not bind clathrin, but can tubulate lipids and is localized on T-tubules. Amphiphysin mutants have a novel phenotype, a severely disorganized T-tubule/sarcoplasmic reticulum system. We therefore propose that muscle amphiphysin is not involved in clathrin-mediated endocytosis, but in the structural organization of the membrane-bound compartments of the excitation-contraction coupling machinery of muscles.

Animals↗
PubMed2001

Molecular cloning and characterization of Atp6n1b: a novel fourth murine vacuolar H+-ATPase a-subunit gene.

The 116-kDa a-subunit of the vacuolar proton pump (H(+)-ATPase) exists as several isoforms encoded by different genes and with different patterns of tissue expression. Its function within the multisubunit pump complex has yet to be elucidated. To date, three isoforms have been identified in mouse (designated a1-a3). We now report the cloning and characterization of Atp6n1b, encoding a novel fourth murine isoform (a4). Murine a4 has 833 residues and shows 85% amino acid identity to the human kidney-specific ATP6N1B protein in which loss-of-function alterations cause autosomal recessive distal renal tubular acidosis. The human and murine genes have similar genomic organization; furthermore, Atp6n1b maps to a region of mouse chromosome 6 that is syntenic with the segment of human 7q33-34 containing ATP6N1B. Together these findings establish the two genes as orthologs. The mouse a4 protein is 61, 52, and 47% identical to a1, a2, and a3, respectively. Phylogenetic analysis confirms that among vertebrates there are four a-subunit families, with a4 most resembling a1. Northern blot analysis of Atp6n1b reveals a 3.7-kilobase a4 transcript in kidney but not other major organs, and a reverse transcription polymerase chain reaction in 12 mouse tissues detects expression in kidney alone. Immunofluorescence studies in murine kidney demonstrate high intensity a4 staining at the surface of intercalated cells, with additional expression in the proximal tubule (not previously reported in human kidney). Similar apical a4 immunostaining is also present in male genital tissue. Identification of this novel murine kidney-enriched 116-kDa a-subunit provides a molecular tool for investigation of the currently unknown role of this protein, which is essential for proper function of the apical renal vacuolar H(+)-ATPase in man.

Amino Acid Sequence↗
PubMed2001

Neutralizing monoclonal antibodies to hepatocyte growth factor/scatter factor (HGF/SF) display antitumor activity in animal models.

The hepatocyte growth factor (HGF/SF) receptor, Met, regulates mitogenesis, motility, and morphogenesis in a cell type-dependent fashion. Activation of Met via autocrine, paracrine, or mutational mechanisms can lead to tumorigenesis and metastasis and numerous studies have linked inappropriate expression of this ligand-receptor pair to most types of human solid tumors. To prepare mAbs to human HGF/SF, mice were immunized with native and denatured preparations of the ligand. Recloned mAbs were tested in vitro for blocking activity against scattering and branching morphogenesis. Our results show that no single mAb was capable of neutralizing the in vitro activity of HGF/SF, and that the ligand possesses a minimum of three epitopes that must be blocked to prevent Met tyrosine kinase activation. In vivo, the neutralizing mAb combination inhibited s.c. growth in athymic nu/nu mice of tumors dependent on an autocrine Met-HGF/SF loop. Importantly, growth of human glioblastoma multiforme xenografts expressing Met and HGF/SF were markedly reduced in the presence of HGF/SF-neutralizing mAbs. These results suggest interrupting autocrine and/or paracrine Met-HGF/SF signaling in tumors dependent on this pathway is a possible intervention strategy.

Animals↗
PubMed2001

ADAR1 is involved in the development of microvascular lung injury.

Deamination of adenosine on pre-mRNA to inosine is a recently discovered process of posttranscription modification of pre-mRNA, termed A-to-I RNA editing, which results in the production of proteins not inherent in the genome. The present study aimed to identify a role for A-to-I RNA editing in the development of microvascular lung injury. To that end, the pulmonary expression and activity of the RNA editase ADAR1 were evaluated in a mouse model of endotoxin (15 mg/kg IP)-induced microvascular lung injury (n=5) as well as in cultured alveolar macrophages stimulated with endotoxin, live bacteria, or interferon. ADAR1 expression and activity were identified in sham lungs that were upregulated in lungs from endotoxin-treated mice (at 2 hours). Expression was localized to polymorphonuclear and monocytic cells. These events preceded the development of pulmonary edema and leukocyte accumulation in lung tissue and followed the local production of interferon-gamma, a known inducer of ADAR1 in other cell systems. ADAR1 was found to be upregulated in alveolar macrophages (MH-S cells) stimulated with endotoxin (1 to 100 microg/mL), live Escherichia coli (5x10(7) colony-forming units), or interferon-gamma (1000 U/mL). Taken together, these data suggest that ADAR1 may play a role in the pathogenesis of microvascular lung injury possibly through induction by interferon.

Adenosine↗
PubMed2001

Subsurface dimerization in III-V semiconductor (001) surfaces.

We present the atomic structure of the c(8 x 2) reconstructions of InSb-, InAs-, and GaAs-(001) surfaces as determined by surface x-ray diffraction using direct methods. Contrary to common belief, group III dimers are not prominent on the surface, instead subsurface dimerization of group III atoms takes place in the second bilayer, accompanied by a major rearrangement of the surface atoms above the dimers to form linear arrays. By varying the occupancies of four surface sites the (001)-c(8 x 2) reconstructions of III-V semiconductors can be described in a unified model.

Journal Article↗
PubMed2001

Acidic pH promotes the formation of toxic fibrils from beta-amyloid peptide.

Beta-amyloid (Abeta) peptides, the major component of senile plaques in brains of patients with Alzheimer's disease (AD), were found in the low pH organelles (i.e. endosome/lysosome) of cultured neuronal cells. Since acidic pH values have been shown to promote the self-assembly of Abetas, which seems to be a prerequisite for their neuropathogenicity, elucidating the aggregation behavior of Abetas in acidic environments and their subsequent effects on neuronal cells may be crucial for understanding the neurodegenerative process of AD. In this study, the extent and rate of aggregation of Abeta(1-42) peptides at pH values of 5.8 and 7.4, as well as the structure and neurotoxic effects of these aggregates, were examined. We showed that Abeta(1-42) peptides formed large and complex fibrils much more efficiently at acidic rather than neutral pH. Furthermore, only the pH 5.8 Abeta aggregates induced significant apoptotic death of PC12 cells, as indicated by a decrease in 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide (MTT) reduction and an increase in phosphatidylserine externalization. Taken together, our results suggest that the Abetas present in the acidic organelles may form neurotoxic fibrils more easily than those in the neutral cellular compartments.

Acids↗
PubMed2001

Local structure of NiTi nanocrystals studied by EXAFS and XRD.

A series of NiTi nanocrystals with different annealing temperatures, prepared by sputtering method, were investigated by extended x-ray absorption fine structure (EXAFS) and x-ray diffraction. It was found that the structure of nano-phase powder is different from bulk NiTi alloy with bcc structure as target materials. When increasing the annealing temperature, a small fraction of the (Ni,Ti) type nanocrystal with the hexagonal structure was presented except target materials and Ni, and it is atomic occupation in random. Finally there were four Ti and two Ni atoms around central Ni atoms, and the bond length of Ni-Ti and Ni-Ni were 0.2462nm and 0.2585nm at 800 degrees C annealed.

Journal Article↗
PubMed2001

A low-power, atmospheric pressure, pulsed plasma source for molecular emission spectrometry.

A low-power, plasma source-based, portable molecular emission detector is described in this paper. The detector employs a pulsed-plasma source operated at atmospheric pressure for molecular fragmentation and excitation. The plasma was generated with a home-built high-voltage pulsed power supply. The average operational power of the detector was less than 0.2 W. The effects of operational parameters such as plasma gas, voltage, and plasma gas flow rate were investigated. Molecular emission spectra of a variety of organic compounds were studied. The features of the emission spectra obtained with the pulsed plasma source were significantly different from those obtained with direct current (dc) discharge at a power higher than 10 W. The spectra obtained in this work showed strong CH emission at 431.2 nm; however, the typical CN emission observed with a conventional dc plasma source at 383-388 nm was very weak in most cases. The strong CN emission was only obtained for compounds containing nitrogen, such as aniline. Dimethyl sulfoxide can be detected at a limit of 200 ppb using helium plasma by observing the emission band of the CH radical. The detector was very stable and did not experience electrode fouling even with the introduction of organic vapors. Such a detector is very promising for organic vapor detection.

Journal Article↗
PubMed2001

Mapping the ion kinetic energy in a helium microwave plasma orthogonal acceleration time-of-flight mass spectrometer.

The ion kinetic energy of a helium microwave plasma is studied using an orthogonal acceleration time-of-flight mass spectrometer. The ions produced in the plasma are extracted into the mass spectrometer in an 'off-cone' mode (i.e. the helium plasma plume is off the sampler cone), and enter the repelling zone in the x-direction, which is perpendicular to the flight tube. The information of ion initial kinetic energy was obtained from both theoretical calculations and experimental results. The potential influence of two x-direction steering plates (X-steering plates) on the ion energy and signal intensity was examined. The influence of gas composition on the ion kinetic energy was also investigated. The calculated results show that ions with different m/z have different velocity and kinetic energy when they enter the ion modulation zone, and lighter ions have higher velocity and lower kinetic energy. The experimental results obtained demonstrate that the ion signals of different m/z produced with an 'off-cone' sampling helium microwave plasma show similar trends as calculated with the potential difference of the X-steering plates, revealing their narrow kinetic energy distribution in the x-direction. Under typical operating conditions, the x-direction kinetic energy of ions detected mostly range from about 14.9 eV for (7)Li(+) to 16.8 eV for (208)Pb(+).

Journal Article↗
PubMed2001

The cross-sectional study of the health effects of occupational exposure to carbon disulfide in a Chinese viscose plant.

This article presents results of carbon disulfide exposure assessment in a Chinese viscose rayon factory and represents the cross-sectional study beginning phase of the occupational epidemiological project. The authors measured external exposure levels to carbon disulfide at a Chinese viscose rayon factory and monitored results as internal exposure indexes by testing urine samples of workers exposed to carbon disulfide levels. The rate at which carbon disulfide is metabolized by exposed subjects was demonstrated by 2-thio-thiazolidine-4-carboxylic acid (TTCA) concentrations in urine of exposed subjects, which was studied to determine best time points for internal exposure sampling. Carbon disulfide concentrations in the air of the workplace were analyzed with gas chromatography with flame photometric detector (GC-FPD); presence of TTCA in urine samples of subjects was determined using a modified high-performance liquid chromatography method. Kinetics of TTCA excretion was studied by analysis at different time points during and after exposure of workers to carbon disulfide. A total of 155 personal samples were obtained. Carbon disulfide concentration at staple viscose hall was found to be 13.72 +/- 1.12 mg/m3 in terms of geometric mean and geometric standard deviation. Carbon disulfide concentration at filament spinning hall was found to be 20.05 +/- 1.33 mg/m3. TTCA values of subjects at staple spinning hall were 1.18 +/- 0.43 and 1.07 +/- 0.38 mg/g creatinine for subjects working at filament spinning hall. The best time for TTCA sampling is at the end of the exposure-working shift.

Adult↗
PubMed2001

Prokaryotically expressed Buthus martensii Karsch insect depressant toxin has insecticidal effects.

An insect depressant toxin Buthus martensii Karsch insect toxin 4 (BmK IT(4)) cDNA was cloned into the prokaryotic expression vector pSW202 and expressed in HB101 host cells. The authenticity of this in vitro expressed peptide was confirmed by Western blotting, mass spectrometry and N-terminal peptide sequencing. Bioassays using growth media supplemented with BmK IT(4) demonstrated that, at the end of the 5-day experimental period, about 77% of the testing cotton bollworm larvae were killed. Furthermore, the average weight picked up by larvae grown on BmK IT(4) containing media amounts only to 0.7% of that of control group. Our results indicate that BmK IT(4) may be used for biological control of insect damages in place of other traditional insecticides.

Amino Acid Sequence↗
PubMed2001

Four new triterpenoid saponins from Conyza blinii.

Three new bisdesmosidic saponins named conyzasaponins A, B, and C (1-3) and one new monodesmosidic saponin, conyzasaponin G (4), were isolated from the aerial parts of Conyza blinii. Their structures were elucidated on the basis of extensive NMR (DEPT, DQF-COSY, HOHAHA, HMQC, HMBC, and NOESY) and MS studies. Compounds 1-3 share a common prosapogenin, bayogenin 3-O-beta-D-xylopyranosyl-(1-->3)-beta-D-glucopyranoside, which is identical with conyzasaponin G (4), and differ in the structures of the ester-linked sugar moieties at C-28. Conyzasaponin A (1) is the 28-O-beta-D-apiofuranosyl-(1-->3)-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl ester, conyzasaponin B (2), the 28-O-beta-D-apiofurano- syl-(1-->3)-beta-D-xylopyranosyl-(1-->4)-[alpha-L-arabinopyranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl ester, and conyzasaponin C (3), the 28-O-alpha-L-rhamnopyranosyl-(1-->3)-beta-D-xylopyranosyl-(1-->4)-[beta-D-apiofuranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl ester of the prosapogenin, respectively.

Carbohydrate Sequence↗
PubMed2001

Actions of the soy phytoestrogen genistein in models of human chronic disease: potential involvement of transforming growth factor beta.

The structural similarity, but non-identity, between 17beta-oestradiol and the soy phytoestrogen genistein suggests that the two compounds will have actions that may be identical in some target biological systems, but different in others. Epidermal growth factor (EGF)-stimulated proliferation of human mammary epithelial cells (that do not express the oestrogen receptor) was significantly suppressed at genistein concentrations (5-10 microM) that are attainable physiologically. Others have shown previously that transforming growth factor beta (TGFbeta) has similar growth-inhibitory effects on human cells. Analysis of the conditioned medium of human mammary epithelial cells exposed to genistein plus EGF showed increased levels of TGFbeta relative to those in the medium of cells exposed to EGF or genistein alone. Related experiments in a primate model of menopause demonstrated that ingestion of soy containing isoflavones was correlated with the suppression of neurodegeneration-relevant phosphorylation of the microtubule-associated protein tau, while intake of Premarin (a hormone replacement therapy that is commonly prescribed for women) was not correlated. The results discussed here indicate that genistein, and probably other related phytoestrogens, have pleiotropic actions, some of which may involve TGFbeta activity.

Animals↗
PubMed2001

Growth of infants during the first 18 months of life in urban and rural areas of southern China.

OBJECTIVE: Observe the growth pattern of infants from birth to 18 months. METHODOLOGY: A prospective study was conducted from 1994 to 1996 in urban and township-rural areas of Guangdong Province, southern China, recruiting 568 and 257 newborn infants, respectively. Anthropometric data was collected at birth, 1.5, 4, 5, 6, 8, 10, 12, 15, and 18 months. RESULTS: The urban infants at birth had Z-scores of weight for age (WAZ), height for age (HAZ) and weight for height (WHZ) below the National Center for Health Statistics (NCHS) median (P < 0.01). However, from 1.5 to 4 months, the WAZ and WHZ scores were above (P < 0.01), but by 7 months fell and remained at - 0.7 to - 0.8 SD below the NCHS median (P < 0.01). HAZ scores improved after birth, were at the NCHS median to 8 months (P = NS), and then decreased to 0.2-0.4 SD below the NCHS median (P < 0.01). Compared with the urban infants, the township-rural infants were lighter and shorter throughout the first 18 months of life, and from 8 months of age, were - 1 SD or more below the NCHS median. CONCLUSIONS: Growth retardation was found in this sample of Chinese infants. The magnitude of growth retardation was greater for infants in the township-rural area compared with those in the urban area.

Age Distribution↗
PubMed2001

Carbon disulfide exposure assessment in a Chinese viscose filament plant.

UNLABELLED: Carbon disulfide is a well-known occupational hazard in the viscose industry, and studies have shown considerable health effects when workers are exposed to high concentrations of this reagent. At exposure levels below the TLV-TWA(31 mg/m3), findings remain contradictory, probably due to deficient exposure data. The present study tries to identify the occupational hazards and thoroughly assess the exposure levels in a Chinese viscose rayon plant. METHODS: An industrial hygienic field survey and a sampling campaign were carried out, including multi-gas monitoring, on-line measurements, and stationary assessment in the spinning hall as well as personal exposure sampling for spinners (by charcoal tube absorbing and GC-FPD analysis). All data was introduced into Foxpro database, and analyzed by Epi info (6.04) and SPSS. RESULTS: On-line measurement showed that the geometric mean (GM) of carbon disulfide exposure amounted to 12.73 mg/m3 in 'exposure' and 0.08 mg/m3 in 'non-exposure' worksites. These concentrations in the air were related to the subject's activities showing the highest levels when they had to open the shield windows of the spinning machines. Stationary exposure measurements of carbon disulfide in the spinning hall amounted to 23.29 mg/m3 GM (range 5.8-97.94 mg/m3). Personal exposure of spinners was about 17.3 mg/m3 GM. Comparing these methods, the personal exposure sampling could exactly express the exposure levels of the worker's contacting situation. The on-line measurement by multi-gas monitor might also be recommended to the factory as it has its own advantages of rapid and independent assessment, but it under-estimates the exposure level.

Air Pollution, Indoor↗
PubMed2001

Theaflavins in black tea and catechins in green tea are equally effective antioxidants.

Green tea catechins, including (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin (EGC) and (-)-epigallocatechin gallate (EGCG), are oxidized and dimerized during the manufacture of black tea and oolong tea to form orange-red pigments, theaflavins (TF), a mixture of theaflavin (TF1), theaflavin-3-gallate (TF2A), theaflavin-3'-gallate (TF2B) and theaflavin-3,3'-digallate (TF3). The present study was designed to compare the antioxidant activities of individual TF with that of each catechin using human LDL oxidation as a model. All catechins and TF tested inhibited Cu(+2)-mediated LDL oxidation. Analysis of the thiobarbituric acid-reactive substances (TBARS) and conjugated dienes produced during LDL oxidation revealed that the antioxidant activity was in the order: TF3 > ECG > EGCG > or = TF2B > or = TF2A > TF1 > or = EC > EGC. Four TF derivatives also demonstrated a dose-dependent antioxidant activity in Cu(+2)-mediated LDL oxidation at concentrations of 5-40 micromol/L. These results demonstrate that the TF present in black tea possess at least the same antioxidant potency as catechins present in green tea, and that the conversion of catechins to TF during fermentation in making black tea does not alter significantly their free radical-scavenging activity.

Antioxidants↗