Biomedical subjects

Jun Li

Publications and source records attributed to Jun Li.

At least 559 records · Page 31Linked to original sources

PubMed2002

[Association of 5-HT(2A) receptor polymorphism and attention deficit hyperactivity disorder in children].

OBJECTIVE: To stude the association of 5-HT(2A) receptor polymorphism and attention deficit hyperactivity disorder (ADHD) in children. METHODS: Blood samples were taken from 323 6 approximately 17.5-year-old children with ADHD disgnosed based on the DSM-IV criteria, 182 healthy 18 approximately 49-year-old controls, and 195 pairs of parents of affected children, all of Han nationality. DNA was extracted. PCR was performed to examine the 5-hydroxytryptamine (5-HT)(2A) receptor T102C polymorphism. Transmission disequilibrium test (TDT) was used to test the association of alleles of 5-HT(2A) T102C polymorphic sites and AFDHD. RESULTS: The frequency of T102T in patients with ADHD combined subtype was lower than that in the controls (22.35 vs 33.5%, OR = 0.569, P = 0.028, 95% CI 0.344 - 0.943), and the frequency of T102C in patients with ADHD combined subtype was higher than that in the controls (64.0% vs 47.3%, OR = 1.987, P = 0.003, 95% CI 1.264 approximately 3.124). TDT showed biased transmission of the alleles of T102C polymorphism among families of girl patients with ADHD combined subtype (P = 0.031). CONCLUSION: For the ADHD combined subtype, the T102T genotype is a protective factor and the T102C genotype is a risk factor. For the girl with ADHD combined subtype, the allele C102 is a disease-predisposing gene.

Adolescent↗

PubMed2002

A beta-tubulin-like cDNA expressed specifically in elongating cotton fibers induces longitudinal growth of fission yeast.

Using cDNA Representational Difference Analysis (RDA) techniques, we isolated a cDNA that was expressed specifically in cotton fibers but not in the ovules of a fuzzless-lintless mutant (fl). We designated it as Gh-BTubL for it shares high sequence identity with known plant and yeast beta-tubulins. RT-PCR and robotic cDNA dot blot analyses indicated that the expression of Gh-BTubL was correlated with the elongation pattern of cotton fibers. In situ hybridization results verified that there was no Gh-BTubL mRNA in fl ovules while it was easily detected in the elongating wild type cotton fiber cells. Overexpression of Gh-BTubL in fission yeast induced longitudinal growth of the host cells by 1.74-fold, with no apparent effect on other aspects of the host cells. We suggest that Gh-BTubL plays an important role in cotton fiber elongation and we believe that elucidation of the control mechanisms for expression of tubulin-like proteins may help improve fiber quality and productivity.

Amino Acid Sequence↗

PubMed2002

IKKalpha, IKKbeta, and NEMO/IKKgamma are each required for the NF-kappa B-mediated inflammatory response program.

The IKKbeta and NEMO/IKKgamma subunits of the NF-kappaB-activating signalsome complex are known to be essential for activating NF-kappaB by inflammatory and other stress-like stimuli. However, the IKKalpha subunit is believed to be dispensable for the latter responses and instead functions as an in vivo mediator of other novel NF-kappaB-dependent and -independent functions. In contrast to this generally accepted view of IKKalpha's physiological functions, we demonstrate in mouse embryonic fibroblasts (MEFs) that, akin to IKKbeta and NEMO/IKKgamma, IKKalpha is also a global regulator of tumor necrosis factor alpha- and IL-1-responsive IKK signalsome-dependent target genes including many known NF-kappaB targets such as serum amyloid A3, C3, interleukin (IL)-6, IL-11, IL-1 receptor antagonist, vascular endothelial growth factor, Ptx3, beta(2)-microglobulin, IL-1alpha, Mcp-1 and -3, RANTES (regulated on activation normal T cell expressed and secreted), Fas antigen, Jun-B, c-Fos, macrophage colony-stimulating factor, and granulocyte-macrophage colony-stimulating factor. Only a small number of NF-kappaB-dependent target genes were preferentially dependent on IKKalpha or IKKbeta. Constitutive expression of a trans-dominant IkappaBalpha superrepressor (IkappaBalphaSR) in wild type MEFs confirmed that these signalsome-dependent target genes were also dependent on NF-kappaB. A subset of NF-kappaB target genes were IKK-dependent in the absence of exogenous stimuli, suggesting that the signalsome was also required to regulate basal levels of activated NF-kappaB in established MEFs. Overall, a sizable number of novel NF-kappaB/IKK-dependent genes were identified including Secreted Frizzled, cadherin 13, protocadherin 7, CCAAT/enhancer-binding protein-beta and -delta, osteoprotegerin, FOXC2 and FOXF2, BMP-2, p75 neurotrophin receptor, caspase-11, guanylate-binding proteins 1 and 2, ApoJ/clusterin, interferon (alpha and beta) receptor 2, decorin, osteoglycin, epiregulin, proliferins 2 and 3, stromal cell-derived factor, and cathepsins B, F, and Z. SOCS-3, a negative effector of STAT3 signaling, was found to be an NF-kappaB/IKK-induced gene, suggesting that IKK-mediated NF-kappaB activation can coordinately illicit negative effects on STAT signaling.

Animals↗

PubMed2002

A new model of hepatitis B virus reinfection: liver transplantation in the woodchuck1.

BACKGROUND: Reinfection of liver grafts with hepatitis B virus (HBV) is a pertinent problem in clinical liver transplantation, requiring the development of new treatment strategies. However, no animal model is currently available to study the course and mechanism of hepatitis B reinfection. This was the reason to establish the technique of liver transplantation in the woodchuck, which is a widely used animal model for HBV infection. MATERIAL AND METHODS: For the reinfection study, woodchuck hepatitis virus (WHV)-negative animals were selected as donors, whereas chronic carriers served as recipients (n=3). Immunosuppression consisted of cyclosporine in a daily dose of 5 mg/kg. Blood and liver samples were obtained before and 8 hr, 3 weeks, and 10 weeks after transplantation. Virological markers included serological testing for WHV DNA, WHV surface antigen (WHsAg), core antigen (WHcAg), and their antibodies (anti-WHs and anti-WHc). WHV DNA replication intermediates and viral RNA were detected by Southern blot hybridization and Northern blot, respectively. Viral proteins in the liver were visualized by immunohistochemistry for WHsAg and WHcAg. RESULTS: Early after transplantation membranous but no intracytoplasmic staining for WHsAg was detected in the liver graft, which was negative for WHcAg as well as WHV-DNA and RNA. Nearly all hepatocytes in the liver grafts of animals killed at 3 weeks and 10 weeks posttransplant showed strong membranous (WHsAg) and intracytoplasmic (WHsAg and WHcAg) staining, which was higher in frequency and intensity than in carriers before transplantation. The apparently reduced level of WHV replication intermediates and viral RNA in the reinfected liver grafts compared with the carrier animals was caused by the severe morphological changes leading to a replacement of hepatocytes by extended portal infiltrates. CONCLUSION: The woodchuck proved to be a suitable model to study WHV reinfection after liver transplantation, because the operative procedure was well tolerated. The first sign of viral presence in the graft was WHsAg detected exclusively in the sinusoids. Reinfection was proven by heavy intracytoplasmic staining for WHsAg and WHcAg in the majority of hepatocytes and detection of viral DNA and RNA in the graft.

Animals↗

PubMed2002

A unique glutamic acid-lysine (EK) domain acts as a splicing inhibitor.

SRrp86 is a unique member of the SR protein superfamily of splicing factors containing one RNA recognition motif and two serine-arginine (SR)-rich domains separated by an unusual glutamic acid-lysine (EK) rich region. Previously, we showed that SRrp86 could regulate alternative splicing by both positively and negatively modulating the activity of other SR proteins as long as the entire region encompassing the RS-EK-RS domains was intact. To further investigate the function and domains of SRrp86, we generated a series of chimeric proteins by swapping the RNA recognition motif and RS domains between SRrp86 and two canonical members of the SR superfamily, ASF/SF2 and SRp75. Although domain swaps between SRrp86 and ASF/SF2 showed that the RRMs primarily determined splicing activity, swaps between SRrp86 and SRp75 demonstrated that the RS domains could also determine activity. Because SRp75 also has two RS domains but lacks the EK domain, we further investigated the role of the EK domain and found that it acts to repress splicing and splice-site selection, both in vitro and in vivo. Incubation of extracts with peptides encompassing the EK-rich region inactivated splicing and insertion of the EK region into SRp75 abolished its ability to activate splicing. Thus, the unique EK domain of SRrp86 plays a modulatory role controlling RS domain function.

Amino Acid Sequence↗

PubMed2002

Noble gas-actinide compounds: evidence for the formation of distinct CUO(Ar)(4-n)(Xe)(n) and CUO(Ar)(4-n)(Kr)(n) (n = 1, 2, 3, 4) complexes.

Laser-ablated U atoms react with CO in excess argon to produce CUO, which gives rise to 852.5 and 804.3 cm-1 infrared absorptions for the triplet state CUO(Ar)n complex in solid argon at 7 K. Relativistic density functional calculations show that the CUO(Ar) complex is stable and that up to four or five argon atoms can complex to CUO. When 1-3% Xe is added to the argon/CO reagent mixture, strong absorptions appear at 848.0 and 801.3 cm-1 and dominate new four-band progressions, which increase on annealing to 35-50 K as Xe replaces Ar in the intimate coordination sphere. Analogous spectra are obtained with 1-2% Kr added. This work provides evidence for eight distinct CUO(Ng)n(Ar)4-n (Ng = Kr, Xe, n = 1, 2, 3, 4) complexes and the first characterization of neutral complexes involving four noble-gas atoms on one metal center.

Journal Article↗

PubMed2002

Simulation of rice biomass accumulation by an extended logistic model including influence of meteorological factors.

The biomass (X) of a biological population, described by growth models, depends only on time (t), i.e., X = f(t). Some parameters in these models are frequently taken as constants, but they may vary with growth processes under different ecological conditions. An extended logistic model including changes in the influence of meteorological factors is developed to simulate biomass accumulation processes of rice sown on different dates. The model may be generally described as X = f (p, t), in which p stands for meteorological factors. The model can be used to generalize population growth processes in experiments carried out under different environments. It is shown that the model may account for 96.6% of the variance of rice biomass on the basis of sowing dates, developmental stage, solar radiation and temperature in the Yangtze River valley in China.

Biomass↗

PubMed2002

The role of high-potential iron protein and cytochrome c(8) as alternative electron donors to the reaction center of Chromatium vinosum.

Under anaerobic conditions, intact cells of the purple sulfur bacterium Chromatium vinosum exhibit rapid photooxidation of the two low-potential hemes of the c-type cytochrome associated with the reaction center, after exposure to two short light flashes separated by a dark interval. Reduction of the photooxidized low-potential hemes is very slow under these conditions. On subsequent flashes, rapid photooxidation of a high-potential reaction center heme occurs and is followed by its rereduction on the millisecond time scale. Cells maintained under aerobic conditions exhibit the millisecond time scale reduction of the photooxidized high-potential heme after each flash. Cells grown autotrophically in the presence of Na(2)S and Na(2)S(2)O(3) appear to use the soluble [4Fe-4S]-containing protein, HiPIP, as the only direct electron donor to the reaction center heme under aerobic conditions. In contrast, cells grown in the presence of organic compounds, but in the absence of Na(2)S and Na(2)S(2)O(3), appear to use a soluble c-type cytochrome (most likely cytochrome c(8)) as the only electron donor to the reaction center heme under aerobic conditions. Cells grown autotrophically, in the presence of Na(2)S and Na(2)S(2)O(3), have a slightly higher ratio of HiPIP to cytochrome c(8) and a ratio of Rieske iron-sulfur protein to reaction center that is approximately one-half that of cells grown in the absence of Na(2)S and Na(2)S(2)O(3) but in the presence of organic compounds.

Aerobiosis↗

PubMed2002

Hereditary neuropathy with liability to pressure palsy: the electrophysiology fits the name.

BACKGROUND: Studies of patients with hereditary neuropathy with liability to pressure palsies (HNPP) have shown accentuated distal slowing along with nonuniform conduction abnormalities at segments liable to compression, suggesting a distal myelinopathy as an underlying pathophysiological mechanism. METHODS: We evaluated 12 patients with HNPP by standard nerve conduction studies and by conduction to more proximal muscles in the arm and leg. Three CMT1A patients and six healthy subjects also were evaluated as controls. RESULTS: Median and peroneal motor nerves in all HNPP patients showed prolonged distal motor latencies (DML) (mean +/- SE, 5.9 +/- 0.41 and 8.63 +/- 0.58 milliseconds), but the ulnar and tibial DML were minimally prolonged or normal (mean +/- SE, 3.87 +/- 0.16 and 5.66 +/- 0.24 milliseconds). DML to forearm flexor (median and ulnar nerves) or anterior tibial muscles (peroneal nerve) were also normal. CONCLUSION: Accentuated distal slowing is found primarily in median and peroneal nerve segments liable to pressure palsies or repetitive trauma. However, the ulnar and tibial nerves, which are less liable to compression, have minimal changes. In addition, distal latencies to more proximal muscles in the arm and leg do not have distal slowing. These findings do not support a distal myelinopathy as a determinant of the conduction abnormalities in HNPP.

Adolescent↗

PubMed2002

Immunochemical characterization and measurement of neuronal type nitric oxide synthase in human neuroblastoma NB-OK-1 cell using novel anti-synthetic peptide antibody and specific immunoassay system.

We developed a sensitive and specific immunoassay system for human neuronal nitric oxide synthase (hnNOS) using synthetic hnNOS(998-1024) peptide and anti-hnNOS(998-1024) antibody. The novel antibody and radioimmunoassay system revealed a typical nNOS protein in human neuroblastoma NB-OK-1 cell (160 kDa, 180 fmol/10(6) cells). The kinetic parameters of the enzyme were K(m)=4.88 microM and V(max)=4.34 pmol/min/mg protein for L-arginine. On incubation of NB-OK-1 cell for 24 h, betamethasone phosphate decreased both nNOS-immunoreactivity (nNOS-IR) and enzymatic activity in the cell dose-dependently. On the other hand, pituitary adenylate cyclase activating polypeptide(1-38) (PACAP38) increased both nNOS-IR and enzymatic activity at concentrations of 10(-10) and 10(-9) M, but inversely decreased both at 10(-7) M. These suggest the positive and negative implications of endogenous NO in proliferation and differentiation of the cell, which support mitogenic activity of NO generated by nNOS in the cell. The present findings also provided evidence that the quantitative change of nNOS protein controls the integrated activity of the enzyme in the cell and, in turn, substantiate the validity and reliability of the present immunoassay system for hnNOS and its practical usefulness.

Amino Acid Sequence↗

PubMed2002

Effect of tail suspension (or simulated weightlessness) on the lumbar intervertebral disc: study of proteoglycans and collagen.

STUDY DESIGN: An experiment to measure the proteoglycan and collagen content of the lumbar intervertebral discs of rats that had been tail-suspended for up to 4 weeks. OBJECTIVES: To determine the effect of tensile force (or simulated weightlessness) on the intervertebral disc. SUMMARY OF BACKGROUND DATA: During space flight the intervertebral disc experiences low compressive force (because of so-called "weightlessness"), which, in turn, produces, among other things, low hydrostatic pressure acting on the disc cells. Although disc cells respond (in vitro) to changes in hydrostatic pressure, it is unclear what effect low levels of hydrostatic pressure have in vivo and whether they lead to a degenerative catabolic process. The rat tail-suspension model is appropriate for studying the effects of tensile force on the disc. The disc (especially the anulus) is subjected to tension during various body movements (e.g., bending stretches the posterior anulus, and twisting tensions the whole anulus). METHODS: Thirty-two Sprague-Dawley rats were tail-suspended for either 2 weeks (16 rats) or 4 weeks (16 rats). Sixteen other rats were left unsuspended for 4 weeks; these were used as controls. At the end of 2 or 4 weeks, as appropriate, the rats were killed and their lumbar spines were removed. In each rat the six lumbar discs were bisected and the discs (anulus and nucleus together) were carefully removed. The six lumbar discs from one rat were pooled with the six lumbar discs of a second matching rat (i.e., from the same group) to give one sample. The disc samples were then assessed using enzyme-linked immunosorbent assays. RESULTS: There was a 35% statistically significant decrease in proteoglycan content going from the control group down to the 4-week group, but no significant differences between the control group and the 2-week group or between the 2-week group and the 4-week group. There were no statistically significant differences between the three groups for collagen I or collagen II. CONCLUSIONS: These findings clearly establish a link between decreased proteoglycan content and tension on the disc, as modeled by the tail-suspended rat.

Animals↗

PubMed2002

Experimental and theoretical studies of the products of laser-ablated thorium atom reactions with H2O in excess argon.

Reactions of laser-ablated Th atoms with H2O during condensation in excess argon have formed a variety of intriguing new Th, H, O species. Infrared absorptions at 1406.0 and 842.6 cm-1 are assigned to the H-Th and Th=O stretching vibrations of HThO. Absorptions at 1397.2, 1352.4, and 822.8 cm-1 are assigned to symmetric H-Th-H, antisymmetric H-Th-H, and Th=O stretching vibrations of the major primary reaction product H2ThO. Thorium monoxide (ThO) produced in the reaction inserts into H2O to form HThO(OH), which absorbs at 1341.0, 804.0, and 542.6 cm-1. Both HThO(OH) and ThO2 add another H2O molecule to give HTh(OH)3 and OTh(OH)2, respectively. Weaker thorium hydride (ThH1(-4)) absorptions were also observed. Relativistic DFT and ab initio calculations were performed on all proposed molecules and other possible isomers. The good agreement between experimental and calculated vibrational frequencies, relative absorption intensities, and isotopic shifts provides support for these first identifications of Th, H, O molecular species.

Journal Article↗

PubMed2002

Methods for parallel-detection-based ultrasound-modulated optical tomography.

The research reported here focuses on ultrasound-modulated optical tomography based on parallel speckle detection. Four methods were investigated for signal acquisition and analysis, in which laser speckle statistics was applied. The methods were compared with the previously used four-phase method in the imaging of all-biological-tissue samples, in which the buried objects were also biological tissues. The image quality obtained with these methods was comparable with that obtained with the four-phase method; in addition, these methods have advantages in reducing acquisition time and improving the signal-to-noise ratio.

Animals↗

PubMed2002

Comparative gene expression profile analysis of neurofibromatosis 1-associated and sporadic pilocytic astrocytomas.

Pilocytic astrocytomas (PAs) are WHO grade I brain tumors that do not typically progress to more malignant grades of astrocytoma. Whereas there have been significant advances in the molecular genetics of high-grade astrocytomas, relatively little is known about the genetic changes associated with PA formation. In an effort to better characterize these low-grade neoplasms, we compared the gene expression profiles of six sporadic and two neurofibromatosis 1-associated PAs with other tissues and cell lines of both astrocytic and oligodendroglial origin. Hierarchical cluster analysis of gene expression data clearly delineated PAs from low-grade oligodendrogliomas and normal white matter. The two NF1-associated tumors and one of the sporadic PAs displayed expression profiles that were more closely related to those of cultured normal human fetal astrocytes. However, PAs also expressed individual genes typically associated with oligodendroglial lineage (e.g., proteolipid protein and PMP-22). The expression patterns of specific genes (e.g., ApoD) were unique to PA tumors, whereas genetic changes characteristic of high-grade astrocytomas were not encountered. Differential expression of two transcripts, neural cellular adhesion molecule and connexin-43, was confirmed at the protein level, suggesting that these cell adhesion molecules might be particularly important in the molecular pathogenesis of these tumors. We conclude that PAs are genetically unique gliomas with gene expression profiles that resemble those of fetal astrocytes and, to a lesser extent, oligodendroglial precursors.

Astrocytoma↗

PubMed2002

Noble gas-actinide compounds: complexation of the CUO molecule by Ar, Kr, and Xe atoms in noble gas matrices.

The CUO molecule, formed from the reaction of laser-ablated U atoms with CO in a noble gas, exhibits very different stretching frequencies in a solid argon matrix [804.3 and 852.5 wave numbers (cm(-1))] than in a solid neon matrix (872.2 and 1047.3 cm(-1)). Related experiments in a matrix consisting of 1% argon in neon suggest that the argon atoms are interacting directly with the CUO molecule. Relativistic density functional calculations predict that CUO can bind directly to one argon atom (U-Ar = 3.16 angstroms; binding energy = 3.2 kilocalories per mole), accompanied by a change in the ground state from a singlet to a triplet. Our experimental and theoretical results also suggest that multiple argon atoms can bind to a single CUO molecule.

Journal Article↗

PubMed2002

[Clinical analysis of 228 patients treated with penctoneal dialysis].

OBJECTIVE: To summarize the treatment with peritoneal dialysis with the "O" set peritoneal dialysis catheter. METHODS: Reviewing the 228 cases of chronic renal failure patients, we compared their blood pressure and hemoglobin before peritoneal dialysis with those after peritoneal dialysis, observed the morbidity of peritonitis and drainage block, and analyzed reasons that the patients withdrew from peritoneal dialysis. RESULTS: The patients' blood pressures were controlled very well after peritoneal dialysis. Hemoglobin increased significantly, compared with that before peritoneal dialysis. Death caused by complications of peritoneal dialysis was the primary reason that the patients withdrew from peritoneal dialysis. CONCLUSION: Peritoneal dialysis is simple, convenient, safe and efficient.

Adolescent↗

PubMed2002

Electronic structure of glassy chalcogenides As4Se4 and As2Se3: a joint theoretical and experimental study.

We present an interpretation of the x-ray absorption spectra of arsenic chalcogenide glasses, As4Se4 and As2Se3, from a first-principles calculation. Our calculation identifies the atomistic origins of the observed photoemission data. The importance of structural "building blocks" present in a particular glass to the electron states is emphasized. The effects of disorder on the electronic spectra are clearly demonstrated by a significant change in the electronic density of states, originating in the breakdown of long-range order coherence in the bonding states of the building blocks. We discuss the relation between observed in situ light-induced changes and the electronic structure.

Journal Article↗

PubMed2002

Lack of association between HoxA1 and HoxB1 gene variants and autism in 110 multiplex families.

A recent report suggested that the HoxA1 and/or HoxB1 genes play a role in susceptibility to autism. To determine whether these findings could be confirmed, we screened these genes for DNA polymorphisms by sequencing all exons in 24 individuals with autism. We identified the same sequence variants in the genes that appeared in this report, which include one single-base substitution variant in HoxA1 and a common haplotype in HoxB1. We performed an association study by applying the transmission disequilibrium test to detect possible association of these variants to autism in 110 multiplex families. Our results demonstrated no deviation from the null hypothesis of no association. We have also separately examined transmissions within individual mating types, for paternal versus maternal alleles, to affected versus unaffected children, and for transmission to affected boys versus girls. None of these subsets revealed significant deviation from the null expectation. Our interpretation of these findings is that it is unlikely that HoxA1 and HoxB1 play a significant role in the genetic predisposition to autism.

Autistic Disorder↗