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Biomedical subjects

S Jin

Publications and source records attributed to S Jin.

At least 37 records · Page 2Linked to original sources
PubMed2005

Strongly nonlinear waves in a chain of Teflon beads.

One-dimensional "sonic vacuum" type phononic crystals were assembled from a chain of polytetrafluoroethylene (PTFE,Teflon) spheres with different diameters in a Teflon holder. It was demonstrated that this polymer-based sonic vacuum, with exceptionally low elastic modulus of particles, supports propagation of strongly nonlinear solitary waves with a very low speed. These solitary waves can be described using the classical nonlinear Hertz law despite the viscoelastic nature of the polymer and high strain rate deformation of the contact area. The experimentally measured speeds of solitary waves at high amplitudes are close to the theoretically estimated values with a Young's modulus of 1.46 GPa obtained from shock wave experiments. This is significantly higher than the Young's modulus of PTFE from ultrasonic measurements. Trains of strongly nonlinear solitary waves excited by an impact were investigated experimentally and were found to be in reasonable agreement with numerical calculations based on Hertz interaction law though exhibiting a significant dissipation.

Journal Article↗
PubMed2005

Identification of one intron loss and phylogenetic evolution of Dfak gene in the Drosophila melanogaster species group.

Intron loss and its evolutionary significance have been noted in Drosophila. The current study provides another example of intron loss within a single-copy Dfak gene in Drosophila. By using polymerase chain reaction (PCR), we amplified about 1.3 kb fragment spanning intron 5-10, located in the position of Tyr kinase (TyK) domain of Dfak gene from Drosophila melanogaster species group, and observed size difference among the amplified DNA fragments from different species. Further sequencing analysis revealed that D. melanogaster and D. simulans deleted an about 60 bp of DNA fragment relative to other 7 Drosophila species, such as D. elegans, D. ficusphila, D. biarmipes, D. takahashii, D. jambulina, D. prostipennis and D. pseudoobscura, and the deleted fragment located precisely in the position of one intron. The data suggested that intron loss might have occurred in the Dfak gene evolutionary process of D. melanogaster and D. simulans of Drosophila melanogaster species group. In addition, the constructed phylogenetic tree based on the Dfak TyK domains clearly revealed the evolutionary relationships between subgroups of Drosophila melanogaster species group, and the intron loss identified from D. melanogaster and D. simulans provides a unique diagnostic tool for taxonomic classification of the melanogaster subgroup from other group of genus Drosophila.

Amino Acid Sequence↗
PubMed2005

Detailed assessment of activities of daily living in moderate to severe Alzheimer's disease.

Patients with Alzheimer's Disease (AD) who have reached a stage of moderate to severe dementia are capable of completing a restricted range of cognitive tests and performing a limited range of activities of daily living (ADL). As part of an initiative to develop instruments to evaluate AD, we analyzed data describing the performance of a large number of ADL and scores on cognitive and global assessment measures in a cohort of patients with AD with moderate to severe cognitive impairment, defined as a Mini-Mental State Examination score ranging from 0-15 (out of 30). From the large pool of ADL, 19 met criteria of applicability, reliability, good scaling, concordant validity, and sensitivity to detect change in performance over 6-12 months. A total score derived from these 19 ADL ratings, comprising a scale termed the Alzheimer Disease Cooperative Study ADL-sev, correlated strongly with measures of cognition and of global dementia severity. Patients with moderate to severe AD showed a decline on the ADL-sev and cognitive measures over 6 and 12 months, consistent with the progression of AD. Detailed evaluation of ADL may provide a useful index to evaluate patients with moderate to severe AD and may complement cognitive assessment, especially for characterizing change in interventional or therapeutic studies.

Activities of Daily Living↗
PubMed2005

Presence of NGF and its receptors in ovaries from human fetuses and adults.

The ability to mature human primordial follicles in vitro would assist fertility restoration. However, the signals initiating growth of primordial follicles are unknown. Growth factors such as nerve growth factor (NGF) may play a role in this process. To investigate the expression of NGF and its receptors, p75 and TrkA, in early developing follicles (mostly primordial, primary and secondary follicles), ten ovarian samples from adolescents/adults aged 13-39 and 33 ovaries from human fetuses aged 19-33 gestational weeks (GW) were obtained and immediately fixed or frozen. The fixed samples were prepared for a study of immunocytochemical staining of NGF and its two receptors. Total RNA was extracted from the frozen ovarian samples, and the expression of NGF, TrkA and p75 was investigated by RT-PCR. Products were resolved by 1% agarose gel electrophoresis and image analysis. Immunocytochemical staining revealed the expression of NGF in granulosa cells (GC) and oocytes; TrkA was mainly in oocytes and in GC in minority of the samples; and p75 was in some of the stroma cells from fetuses aged less than 22 GW. Transcripts of NGF and TrkA were identified by RT-PCR in all samples, while those for p75 were detected only in ovarian samples from fetuses aged less than 22 GW. To elucidate if NGF is indeed involved in growth initiation of human primordial follicles, it should be added to their culture medium. The immunocytochemical detection of p75 in some of the stroma cells and transcripts in ovarian samples of fetuses less than 22 GW may suggest its role in follicular assembly.

Adolescent↗
PubMed2005

Nocardiosis in large yellow croaker, Larimichthys crocea (Richardson).

An epizootic in seawater-cage reared large yellow croaker, Larimichthys crocea, in China was caused by a Nocardia sp. from August to October 2003. The cumulative mortality rate was 15% and the diseased fish were 16 months old with individual length varying from 25 to 30 cm. Multiple, white nodules, 0.1-0.2 cm in diameter, were scattered on the heart, spleen and kidney. The morphology of isolated bacteria from Lowenstein-Jensen medium and tryptic soy agar was bead-like or long, slender, filamentous rods. Experimental infection indicated that the isolated bacterium was the pathogen responsible for the mortalities. A partial sequence of the 16S rRNA gene of the organism and the type strain of Nocardia seriolae JCM 3360T (Z36925) formed a monophyletic clade with a high sequence similarity of 99.9%. Based on the morphological, physiological, biological properties and the phylogenetic analysis, the pathogenic organism was identified as N. seriolae. This is the first report on N. seriolae-infected large yellow croaker in aquaculture.

Animals↗
PubMed2005

A model of cytokine shedding induced by low doses of gamma radiation.

A model for sustained shedding of epidermal growth factor (EGF) in response to low doses of gamma radiation was developed based on a time delay in the feedback from mitogen-activated protein kinase (MAPK) activation to metalloprotease activity in an autocrine signaling process. We determined the kinetic parameters of our model using the data available for MAPK activation by gamma irradiation in the 1-2-Gy dose range and then showed that predictions of the model were consistent with experimental results for the kinetics of EGF shedding into the growth medium after exposure of human mammary epithelial cells to 1-5 cGy of gamma radiation in the presence of antibodies that block ligand binding to EGF receptors. The model allowed us to estimate the rate of radiation-induced cytokine release per cell from measurements of EGF concentration in the growth medium and to assess the effectiveness of EGF shedding and subsequent diffusion through the medium as a mechanism for signal transmission between hit cells and bystanders.

Cell Proliferation↗
PubMed2004

Observation of a threshold enhancement in the plambda invariant-mass spectrum.

An enhancement near the m(p)+M(Lambda) mass threshold is observed in the combined pLambda and pLambda invariant-mass spectrum from J/psi-->pK(-)Lambda;+c.c. decays. It can be fit with an S-wave Breit-Wigner resonance with a mass m=2075+/-12(stat)+/-5(syst) MeV and a width of Gamma=90+/-35(stat)+/-9(syst) MeV; it can also be fit with a P-wave Breit-Wigner resonance. Evidence for a similar enhancement is also observed in psi(')-->pK(-)Lambda;+c.c. decays. The analysis is based on samples of 5.8x10(7)J/psi and 1.4x10(7)psi(') decays accumulated in the BES II detector at the Beijing Electron-Positron Collider.

Journal Article↗
PubMed2004

Immunocytochemical detection and RT-PCR expression of leukaemia inhibitory factor and its receptor in human fetal and adult ovaries.

The ability to mature human primordial follicles in vitro would assist fertility restoration. However, the signals initiating growth of primordial follicles are unknown. Growth factors such as leukaemia inhibitory factor (LIF) may play a role in this process. To investigate the expression of LIF and its receptor in early developing follicles, nine ovarian samples from adolescents/adults aged 13-43 years and 23 ovaries from human fetuses aged 19-33 gestational weeks were immediately fixed or frozen. The fixed samples were prepared for a study of immunocytochemical staining of LIF and its two receptor units (LIF-R and gp 130). mRNA was extracted from the frozen ovarian samples, and the expression of LIF, LIF-R and gp 130 was investigated by RT-PCR. Products were resolved by 10% polyacrylamide gel electrophoresis and image analysis. There was strong to moderate immunocytochemical staining for LIF and LIF-R in oocytes from the primordial follicular stages onwards, and very weak to moderate staining for gp 130. LIF-R was also detected in granulosa cells of primary and secondary follicles from adolescents/adults. Transcripts of LIF, LIF-R and gp 130 RNA were identified by RT-PCR in all samples. The immunocytochemical staining and mRNA expression of LIF and its receptor are consistent with the concept that LIF might be involved in growth initiation of human primordial follicles through its receptor.

Adolescent↗
PubMed2004

Observation of the decay psi(2S)-->K0SK0L.

The decay psi(2S)-->K(0)(S)K(0)(L) is observed using psi(2S) data collected with the Beijing Spectrometer at the Beijing Electron-Positron Collider; the branching fraction is determined to be B(psi(2S)-->K(0)(S)K(0)(L))=(5.24+/-0.47+/-0.48)x10(-5). Compared with J/psi-->K(0)(S)K(0)(L), the psi(2S) branching fraction is enhanced relative to the prediction of the perturbative QCD "12%" rule. The result, together with the branching fractions of psi(2S) decays to other pseudoscalar meson pairs (pi(+)pi(-) and K+K-), is used to investigate the relative phase between the three-gluon and the one-photon annihilation amplitudes of psi(2S) decays.

Journal Article↗
PubMed2004

FlaC, a protein of Campylobacter jejuni TGH9011 (ATCC43431) secreted through the flagellar apparatus, binds epithelial cells and influences cell invasion.

Type III secretion systems identified in bacterial pathogens of animals and plants transpose effectors and toxins directly into the cytosol of host cells or into the extracellular milieu. Proteins of the type III secretion apparatus are conserved among diverse and distantly related bacteria. Many type III apparatus proteins have homologues in the flagellar export apparatus, supporting the notion that type III secretion systems evolved from the flagellar export apparatus. No type III secretion apparatus genes have been found in the complete genomic sequence of Campylobacter jejuni NCTC11168. In this study, we report the characterization of a protein designated FlaC of C. jejuni TGH9011. FlaC is homologous to the N- and C-terminus of the C. jejuni flagellin proteins, FlaA and FlaB, but lacks the central portion of these proteins. flaC null mutants form a morphologically normal flagellum and are highly motile. In wild-type C. jejuni cultures, FlaC is found predominantly in the extracellular milieu as a secreted protein. Null mutants of the flagellar basal rod gene (flgF) and hook gene (flgE) do not secrete FlaC, suggesting that a functional flagellar export apparatus is required for FlaC secretion. During C. jejuni infection in vitro, secreted FlaC and purified recombinant FlaC bind to HEp-2 cells. Invasion of HEp-2 cells by flaC null mutants was reduced to a level of 14% compared with wild type, suggesting that FlaC plays an important role in cell invasion.

Bacterial Adhesion↗
PubMed2003

Observation of a near-threshold enhancement in the pp mass spectrum from radiative J/psi-->gammapp decays.

We observe a narrow enhancement near 2m(p) in the invariant mass spectrum of pp pairs from radiative J/psi-->gammapp decays. No similar structure is seen in J/psi-->pi(0)pp decays. The results are based on an analysis of a 58 x 10(6) event sample of J/psi decays accumulated with the BESII detector at the Beijing electron-positron collider. The enhancement can be fit with either an S- or P-wave Breit-Wigner resonance function. In the case of the S-wave fit, the peak mass is below 2m(p) at M=1859(+3)(-10) (stat)+5-25(syst) MeV/c(2) and the total width is Gamma<30 MeV/c(2) at the 90% confidence level. These mass and width values are not consistent with the properties of any known particle.

Journal Article↗
PubMed2002

The p53MH algorithm and its application in detecting p53-responsive genes.

A computer algorithm, p53MH, was developed, which identifies putative p53 transcription factor DNA-binding sites on a genomewide scale with high power and versatility. With the sequences from the human and mouse genomes, putative p53 DNA-binding elements were identified in a scan of 2,583 human genes and 1,713 mouse orthologs based on the experimental data of el-Deiry et al. [el-Deiry, W. S., Kern, S. E., Pietenpol, J. A., Kinzler, K. W. & Vogelstein, B. (1992) Nat. Genet. 1, 45-49] and Funk et al. [Funk, W. D., Pak, D. T., Karas, R. H., Wright, W. E. & Shay, J. W. (1992) Mol. Cell. Biol. 12, 2866-2871] (http://linkage.rockefeller.edu/p53). The p53 DNA-binding motif consists of a 10-bp palindrome and most commonly a second related palindrome linked by a spacer region. By scanning from the 5' to 3' end of each gene with an additional 10-kb nucleotide sequence appended at each end (most regulatory DNA elements characterized in the literature are in these regions), p53MH computes the binding likelihood for each site under a discrete discriminant model and then outputs ordered scores, corresponding site positions, sequences, and related information. About 300 genes receiving scores greater than a theoretical cut-off value were identified as potential p53 targets. Semiquantitative reverse transcription-PCR experiments were performed in 2 cell lines on 16 genes that were previously unknown regarding their functional relationship to p53 and were found to have high scores in either proximal promoter or possible distal enhancer regions. Ten (approximately 63%) of these genes responded to the presence of p53.

Algorithms↗
PubMed2001

Positive and negative modulation by AMPA- and kainate-receptors of striatal kainate injection-induced neuronal loss in rat forebrain.

We investigated the roles of ionotropic glutamate receptor subtypes in mediating striatal kainate injection-induced neuronal loss in rat forebrain, using subtype-specific antagonists and histochemical staining. Our study demonstrates that kainate injected unilaterally into the striatum induces a massive neuronal loss in the rat ipsilateral forebrain through activation of kainate receptors and, to a limited extent, a consequent involvement of M-methyl-D-aspartate (NMDA) receptors, whereas activation of alpha-amino-3-hydroxy-5-methylisoxazol-4-propionate (AMPA) receptors shows a neuroprotective effect. These and previous results suggest that three subtypes of ionotropic glutamate receptors play differential roles in mediating excitatory amino acid (EAA)-induced neurodegeneration.

Animals↗
PubMed2001

Uncoating of clathrin-coated vesicles in presynaptic terminals: roles for Hsc70 and auxilin.

We have examined the roles of Hsc70 and auxilin in the uncoating of clathrin-coated vesicles (CCVs) during neuronal endocytosis. We identified two peptides that inhibit the ability of Hsc70 and auxilin to uncoat CCVs in vitro. When injected into nerve terminals, these peptides inhibited both synaptic transmission and CCV uncoating. Mutation of a conserved HPD motif within the J domain of auxilin prevented binding to Hsc70 in vitro and injecting this mutant protein inhibited CCV uncoating in vivo, demonstrating that the interaction of auxilin with Hsc70 is critical for CCV uncoating. These studies establish that auxilin and Hsc70 participate in synaptic vesicle recycling in neurons and that an interaction between these proteins is required for CCV uncoating.

Adaptor Proteins, Vesicular Transport↗
PubMed2001

Involvement of the MAP kinase pathways in induction of GADD45 following UV radiation.

The p53-regulated stress-inducible gene GADD45 has been shown to participate in cellular response to DNA damage, including cell cycle checkpoint, apoptosis, and DNA repair. However, the regulation of GADD45 expression is complex and may involve both p53-dependent and -independent pathways. Recent findings have demonstrated that the p53-independent induction of GADD45 is mainly regulated by the transcription factors Oct-1 and NF-YA, which directly bind to their consensus motifs located at the GADD45 promoter region. Here, we report that mitogen-activated protein (MAP) kinases are involved in the induction of the GADD45 promoter after DNA damage. Inhibition of JNK1 and ERK kinase activities either by expression of the dominant negative mutant JNK1 or by treatment with a selective chemical inhibitor of ERK (PD098059) substantially abrogates the UV induction of the GADD45 promoter. In contrast, a p38 kinase inhibitor (SB203580) has little effect on GADD45 induction by UV. In addition, the GADD45 promoter is strongly activated following expression of JNK1; Raf-1, which is an upstream activator of the ERK pathway; or MEK1, an upstream activator of both the ERK and the JNK pathways. Activation of the GADD45 promoter by MAP kinases does not require normal p53 function. Interestingly, the MAP kinase-regulatory effect appears to be mediated via OCT-1 and CAAT motifs since disruption of these sites abrogates activation of the GADD45 promoter by MAP kinases. Therefore, these findings indicate that the MAP kinase pathways are involved in the regulation of the p53-independent induction of the GADD45 promoter, probably via interaction with transcription factors that directly bind to OCT-1 and CAAT motifs.

Amino Acid Motifs↗
PubMed2001

A catalase gene of Colletotrichum gloeosporioides f. sp. malvae is highly expressed during the necrotrophic phase of infection of round-leaved mallow, Malva pusilla.

A small-subunit peroxisomal catalase gene, cgcat1, was cloned from Colletotrichum gloeosporioides f. sp. malvae, a hemibiotrophic pathogen of round-leaved mallow (Malva pusilla). When compared to the expression of an actin gene of the fungus, a much lower level of expression of cgcat1 was detected in the biotrophic phase than in the subsequent necrotrophic phase of infection. In culture, cgcat1was expressed at higher levels when exposed to hydrogen peroxide. Changes in cgcat1 expression during infection may have related to an attempt to prevent damage from hydrogen peroxide from degenerating host cells, and/or resulted from changes in fungal nutrition and development during invasion of the host.

Actins↗
PubMed2001

Synthesis and characterization of oxidized W(6)S(8)L(6) clusters.

Cationic [W(6)S(8)L(6)]PF(6) (L = PEt(3) (3), 4-tert-butylpyridine (4)) clusters were successfully synthesized and isolated for the first time by reacting the corresponding neutral W(6)S(8)L(6) (L = PEt(3) (1), 4-tert-butylpyridine (2)) clusters with [Cp(2)Fe]PF(6) as the oxidant. The products 3 and 4 were characterized by NMR spectroscopy, mass spectroscopy, and X-ray crystallography (only for 3) and shown to be the desired oxidized W(6)S(8) clusters with a metal electron count of 19. Magnetic property studies showed that they are paramagnetic compounds with S = (1)/(2). Their chemical properties and stability are also reported. Crystal data for 3.2 THF: space group, R3 (No. 148); a = 13.91170(10) A; c = 32.4106(2) A; Z = 3.

Journal Article↗