Biomedical subjects

X Jin

Publications and source records attributed to X Jin.

At least 109 records · Page 6Linked to original sources

PubMed1999

[Studies on packing bag and technique for storing up Codonopsis in quality guaranteed].

Under different roots water contents and storing temperature degree, vacuum packing, nitrogen gas packing, carbon dioxide packing were used with different packing bag, to select and study the optimum packing bags and techniques for storing up Codonopsis in quality guaranteed. The results showed that, below the 15% water contents for Codonopsis roots, the two ways of vacuum packing bag with nitrogen gas or carbon dioxide packing and vacuum packing are quite efficient for quality guranteed in Codonopsis.

Carbon Dioxide↗

PubMed1998

Laminar shear stress-induced GRO mRNA and protein expression in endothelial cells.

BACKGROUND: The shear stress induced by blood flow may play a pivotal role in the induction or prevention of atherosclerosis by changing endothelial functions. To disclose the mechanisms of this change, we prepared an endothelial cell (EC) cDNA library to select specific clones expressed in response to shear stress. METHODS AND RESULTS: The mRNA of cultured confluent bovine aortic ECs (BAECs) subjected to steady laminar shear stress (30 dyne/cm2) for 4 hours was separated, and a cDNA library was prepared. Nine clones whose expressions were specifically enhanced by the shear stress were selected by use of a differential hybridization method. One clone had 94% homology at the nucleotide sequence level to Oryctolagus cuniculus gro (GRO) mRNA and 79% homology at the amino acid sequence level to human GRO-beta. The GRO mRNA expression was increased in both BAECs and human umbilical vein ECs (HUVECs) after the ECs were subjected to high (30 dyne/cm2) and low (5 dyne/cm2) laminar shear stress. GRO-alpha and/or -beta protein expression also increased after the HUVECs and BAECs were subjected to shear stress. Because GRO protein has been shown to function as an adhesion factor of monocytes on the surface of ECs, we studied whether shear stress-induced monocyte adhesion was caused by GRO protein expression on ECs. The 4-hour shear stress enhanced monocyte adhesion to ECs by 2.5-fold over control levels, and this enhancement was inhibited by 53% by anti-GRO-alpha antibody. CONCLUSIONS: The present study is the first report that shear stress induced the expression of GRO mRNA and protein in ECs and enhanced the monocyte adhesion on ECs via GRO protein. Further investigations of the functions and participation in atherogenesis of this selected clone may clarify the significance of shear stress on atherogenesis.

Animals↗

PubMed1998

The effect of ACPD on the responses to NMDA and AMPA varies with layer in slices of rat visual cortex.

The effect of 1S,3R-aminocyclopentane dicarboxylic acid (ACPD) was measured on cells from various layers in slices of the rat visual cortex using whole-cell recording techniques. The position of the recorded cell was estimated by distance from pia to the layer VI/white matter boundary, and verified in 34/97 cells by staining with biocytin. Potentiation or depression of the responses to NMDA and AMPA by the metabotropic glutamate agonist ACPD was examined by iontophoresis of the drugs close to the cell body. Iontophoresis of ACPD had different effects in different layers. In layer VI, ACPD produced a substantial depolarization, which augmented the responses to NMDA and AMPA. In layer V, ACPD did not produce a significant depolarization, but potentiated the response to NMDA and AMPA. In layer IV, ACPD produced a small hyperpolarization, and depressed the response to NMDA. In layers II and III, the results were small and variable. Most recordings from stained cells were from pyramidal cells. Where recordings from non-pyramidal cells were obtained (3/34), results were the same as from pyramidal cells in the same layer. The same results were obtained when tetrodotoxin was in the bath solution. We conclude that the potentiation or depression of the response to NMDA and AMPA by ACPD varies with layer in rat visual cortex.

Animals↗

PubMed1998

The group III metabotropic glutamate receptor agonist, l-AP4, reduces EPSPs in some layers of rat visual cortex.

The action of the specific Group III metabotropic glutamate receptor, l-2-amino-4-phosphonobutanoic acid (l-AP4) was tested in slices of rat visual cortex. When the predominant input to the cell was stimulated, l-AP4 generally reduced the EPSP that was produced. This result was specific to the layer: it was found when recording cells in layers II/III, V and VI, but not when recording cells in layer IV. The effect was the same when G-proteins in the cell recorded were inactivated. Also, l-AP4 had little effect on membrane potential and input impedance of the cell recorded, and little effect on the response to NMDA in that cell. Thus, Group III metabotropic glutamate receptors act presynaptically to reduce the release of glutamate onto cells in layers II/III, V and VI in visual cortex, but not cells in layer IV.

Alanine↗

PubMed1998

Isolation of two functional retinoid X receptor subtypes from the Ixodid tick, Amblyomma americanum (L.).

Retinoid X receptors (RXR) play a central role in a variety of nuclear signaling pathways in both vertebrates and invertebrates. Vertebrate RXRs are encoded by a multigene family whereas the insect RXR homologue, ultraspiracle (USP), is encoded by a single gene. To determine if acarines possess an RXR homologue similar to insect USPs, we isolated cDNAs encoding two distinct RXR genes, AamRXR1 and AamRXR2, from the ixodid tick, Amblyomma americanum (L.). The DNA binding domains share 95 and 87% identity, respectively, with DNA binding domains from insect USP and vertebrate RXR proteins. However, the ligand binding domains of the AamRXRs are more similar to vertebrate RXRs than to insect USP ligand binding domains (approximately 71 vs approximately 52%). Northern blot and RT-PCR analysis reveal both unique and overlapping patterns of AamRXR1 and AamRXR2 expression. Transactivation analysis show that both AamRXRs encode proteins which can form functional ecdysteroid receptors but are unlikely to bind retinoic acids.

Alternative Splicing↗

PubMed1998

Quantitation of HIV-1-specific cytotoxic T lymphocytes and plasma load of viral RNA.

Although cytotoxic T lymphocytes (CTLs) are thought to be involved in the control of human immunodeficiency virus-type 1 (HIV-1) infection, it has not been possible to demonstrate a direct relation between CTL activity and plasma RNA viral load. Human leukocyte antigen-peptide tetrameric complexes offer a specific means to directly quantitate circulating CTLs ex vivo. With the use of the tetrameric complexes, a significant inverse correlation was observed between HIV-specific CTL frequency and plasma RNA viral load. In contrast, no significant association was detected between the clearance rate of productively infected cells and frequency of HIV-specific CTLs. These data are consistent with a significant role for HIV-specific CTLs in the control of HIV infection and suggest a considerable cytopathic effect of the virus in vivo.

Anti-HIV Agents↗

PubMed1998

Determination of the sites of posttranslational modifications in the charge isomers of bovine myelin basic protein by capillary electrophoresis-mass spectroscopy.

The posttranslational modifications in each of the 18.5 kDa bovine myelin basic protein charge isomers C-1 to C-6 have been determined by the use of capillary electrophoresis-mass spectroscopy. The pattern of modifications is viewed as being unique to each charge isomer and is thought to reflect a specific placement and function for each isomer in the myelin membrane. Several of the sites of posttranslational phosphorylation were found to differ from a number of the reported sites that were phosphorylated in vitro by various kinases. These differences suggest that an extremely cautious approach be taken in identifying in vivo posttranslationally modified amino acid residues from residues that have been modified in vitro by various kinases. We have identified the following posttranslationally phosphorylated and deamidated, modified sites in the bovine MBP components C1-C6. C1 has no modification; C2 represents a deamidation of Gln 146; in C3, Thr 97 and Ser 164 are phosphorylated; in C4, Ser 54, Thr 97, and Ser 160 are phosphorylated; in C5 Ser 7, Ser 54, Thr 97, and Ser 164 are phosphorylated; and in C6, Ser 7, Ser 54, Thr 97, Ser 160, and Ser 164 are phosphorylated.

Amino Acid Sequence↗

PubMed1998

Expression of p16 induces transcriptional downregulation of the RB gene.

The RB and p16(INK4A) tumor suppressor genes function in the same pathway of cell cycle control. Previous evidence indicates that the p16(INK4A) gene is transcriptionally repressed by the RB gene product, pRB. In this study using human ovarian cancer cell lines, we found that RB protein and mRNA were expressed at higher levels in cell lines lacking p16 than in those with normal p16. Since this suggests a potential role of p16 in regulating the cellular level of pRB, we studied the effect of wild-type p16(INK4A) on expression of the RB gene. Introduction of p16(INK4A), carried by an adenovirus vector, into p16-negative cell lines dramatically decreased expression of RB protein and mRNA. Nuclei run-off assays demonstrated that p16 expression induced transcriptional downregulation of the RB gene. These results indicate that expression of RB is inversely regulated by p16. The findings reveal a new dimension of pRB-p16 interaction and should have implications for p16(INK4A)-mediated gene therapy.

Adenoviridae↗

PubMed1998

Progressive loss of IL-2-expandable HIV-1-specific cytotoxic T lymphocytes during asymptomatic HIV infection.

In HIV-1 infection, circulating HIV-1-specific cytotoxic T lymphocytes (CTL) exist in different states of activation, including activated cytotoxic cells and memory cells. We report that a subpopulation of HIV-1-specific CTL is capable of clonal expansion upon culture with IL-2 without exogenous antigen. The IL-2-expandable HIV-1-specific CTL precursor frequency was reduced in patients with advancing infection, although HIV-1-specific memory CTL could still be detected by stimulation in vitro with allele-specific HIV-1 peptide. Longitudinal analysis during advancing infection showed a progressive decline in the IL-2-expandable HIV-1-specific CTL precursor (CTLp) frequency without a decline in Epstein-Barr virus (EBV)-specific or allo-specific CTLp frequencies. To address mechanisms that may contribute to the decline in the IL-2-expandable HIV-specific CTL response, the requirements for in vitro generation of HIV-1-specific and EBV-specific effector CTL were examined. In the absence of exogenous IL-2 in limiting dilution, generation of EBV-specific CD8+ effector CTL was dependent upon help from CD4+ cells. CD4+ help for EBV-specific CD8+ CTL was observed in asymptomatic HIV infection but not in advanced infection. In the presence of exogenous IL-2, CD4+ cells could also provide help for the optimal generation of HIV-1 peptide-specific CD8+ CTL, because in vitro depletion of CD4+ cells prior to culture using stimulation with an MHC class I-restricted HIV-1 peptide reduced the peptide-specific CD8+ CTL response. We conclude that there is a decline in the IL-2-expandable HIV-1-specific CTL response during advancing infection. There are a number of possible mechanisms for this decline, including a reduction in CD4+ T cell help for in vivo antigen-activated CD8+ T cells.

Acquired Immunodeficiency Syndrome↗

PubMed1998

The structure and function of A1 and A2B adenosine receptors.

Of the four G protein coupled adenosine receptor (AR) subtypes, the A1 is best suited for studies of reconstitution with G proteins. Recombinant A1 receptors extended with hexahistidine and FLAG have been purified to near homogeneity. In reconstitution assays using pure recombinant G protein subunits, the composition of the gamma subunit influences coupling to purified A1ARs. The least well characterized AR is the A2B. New data indicate that A(2B)ARs can trigger the degranulation of canine and human mast cell lines. Recombinant human A(2B)ARs are blocked by the anti-asthma drugs theophylline and enprofylline at concentrations that are used therapeutically to treat asthma. Although A(2B)ARs have long been known to stimulate adenylyl cyclase, they also can activate phospholipase C and mobilize Ca2+ by signaling through Gq/11. There is great potential for new therapies based on compounds that selectively target individual AR subtypes.

Animals↗

PubMed1998

Molecular analysis of mammalian timeless.

We cloned the mouse cDNA of a mammalian homolog of the Drosophila timeless (tim) gene and designated it mTim. The mTim protein shows five homologous regions with Drosophila TIM. mTim is weakly expressed in the suprachiasmatic nuclei (SCN) but exhibits robust expression in the hypophyseal pars tuberalis (PT). mTim RNA levels do not oscillate in the SCN nor are they acutely altered by light exposure during subjective night. mTim RNA is expressed at low levels in several peripheral tissues, including eyes, and is heavily expressed in spleen and testis. Yeast two-hybrid assays revealed an array of interactions between the various mPER proteins but no mPER-mTIM interactions. The data suggest that PER-PER interactions have replaced the function of PER-TIM dimers in the molecular workings of the mammalian circadian clock.

Amino Acid Sequence↗

PubMed1998

Longitudinal and cross-sectional analysis of cytotoxic T lymphocyte responses and their relationship to vertical human immunodeficiency virus transmission. ARIEL Project Investigators.

The ARIEL Project for the Prevention of HIV Transmission from Mother to Infant was established to evaluate virologic and immunologic parameters during vertical transmission. To determine the strength and breadth of the cytotoxic T lymphocyte (CTL) response and its correlation with human immunodeficiency virus (HIV) transmission, a cross-sectional study was done of 31 HIV-infected pregnant women, of whom 15 transmitted and 16 did not transmit HIV to their infants. The precursor frequencies of CTL specific for HIV-1 gag, pol, nef, and env from 5 different isolates of the clade B of HIV-1 were determined by limiting dilution analysis. Results showed that variable levels of HIV-specific CTL response were present in HIV-infected pregnant women during and after pregnancy. In addition, CTL precursor frequencies specific for pol and nef were higher during pregnancy in nontransmitters than in transmitters. Thus, CTL responding to different HIV antigens may not be contributing equally to the prevention of vertical transmission.

Adult↗

PubMed1998

Description of Saccharomonospora xinjiangensis sp. nov. based on chemical and molecular classification.

Comparative studies of morphology, physiology, biochemistry and chemical composition of cells, and phylogenetic analysis based on 16S rRNA gene sequences were carried out with strains XJ-54T and XJ-58 of the genus Saccharomonospora and type strains of related genera. The results indicated that the two strains are different from known members of the genus Saccharomonospora. A new species with the name Saccharomonospora xinjiangensis sp. nov. is proposed. The new species is characterized by the presence of longitudinal pairs of spores on both the aerial and the vegetative hyphae and contains phosphatidyl ethanolamine, phosphatidyl choline and unknown glucosamine-containing phospholipids, and the major menaquinones MK-9(H2), MK-9(H4) and MK-7(H4).

Actinomycetales↗

PubMed1998

Persistent antibody responses but declining cytotoxic T-lymphocyte responses to multiple human immunodeficiency virus type 1 antigens in a long-term nonprogressing individual with a defective p17 proviral sequence and no detectable viral RNA expression.

Long-term nonprogressor AD-18 has been infected with human immunodeficiency virus type 1 (HIV-1) for at least 16 years. During the past 5 years, he has had undetectable levels of plasma viremia, and HIV-1 cannot be isolated from him. Sequencing of proviral DNA indicates that the only HIV-1 sequences that can be identified in AD-18 have gross defects in the p17-encoding regions of the gag gene (Y. Huang, L. Zhang, and D. D. Ho, Virology 240:36-49, 1998). However, AD-18 has strong, sustained antibody responses to several HIV-1 antigens, including p17. Cytotoxic T-lymphocyte responses to Env and Gag antigens have gradually diminished over the past 4 years, at a time when the titers of antibodies to the same proteins have remained stable. We discuss what these observations might mean for the generation and maintenance of immunological memory.

Dendritic Cells↗

PubMed1998

Decreases in organ blood flows associated with increases in sublingual PCO2 during hemorrhagic shock.

Earlier studies demonstrated that not only the stomach but also the esophageal wall served as an appropriate site for estimating the severity of circulatory shock by using tonometric methods. We then conceived of the option of sublingual tonometry. In the present study, we tested the hypothesis that the changes in sublingual PCO2 serve as indicators of decreases in blood flow to sublingual and visceral tissue. In Sprague-Dawley rats, sublingual PCO2 increased from 50 to 127 Torr and arterial blood lactate increased from 0.9 to 11.2 mmol/l during bleeding. Sublingual blood flow simultaneously decreased to approximately 32% of preshock values. After reinfusion of shed blood, organ blood flows and sublingual PCO2 were promptly restored to near-baseline values. There were corresponding decreases in blood flows in the tongue, stomach, jejunum, colon, and kidneys during hemorrhagic shock. Increases in sublingual PCO2 were highly correlated with decreases in sublingual blood flow (r = 0.80), tongue blood flow (r = 0.81), gastric blood flow (r = 0.74), jejunal blood flow (r = 0.65), colon blood flow (r = 0.80), and renal blood flow (r = 0.75). Unbled control animals demonstrated no significant changes. Therefore, we anticipate that sublingual tonometry will provide a useful, noninvasive alternative for monitoring visceral PCO2.

Animals↗

PubMed1998

Sublingual capnometry for diagnosis and quantitation of circulatory shock.

We investigated sublingual tissue PCO2 during hemorrhagic and septic shock. Hemorrhagic shock was induced in 10 rats. Sublingual PCO2 increased from 45 to 125 mm Hg and arterial pressure declined from 138 to 49 mm Hg, end-tidal PCO2 decreased from 35 to 13 mm Hg, and cardiac index fell from 290 to 77 ml/min/kg. Arterial blood lactate increased from 0.9 to 15.8 mmol/L. Gastric PCO2 was measured in five animals and it increased from 46 to 87 mm Hg. No significant changes were observed in eight "sham" bled animals including the five animals in which gastric PCO2 was measured. Highly significant linear correlations (p < 0.001) between sublingual PCO2 and gastric PCO2 (r = 0.71), cardiac index (r = -0.74), and arterial lactate (r = 0.59) were documented. We subsequently investigated sublingual PCO2 in five animals in which sepsis was induced by intravenous infusion of live Staphylococcus aureus. Like hemorrhagic shock, highly significant linear correlations were observed between end-tidal PCO2 and cardiac index and between sublingual PCO2 and arterial blood lactate. Sublingual PCO2 promises to serve as a technically simple, noninvasive, and rapid response quantitator of severity of circulatory shock states.

Animals↗

PubMed1998

[VP-16 and VM-26 plus platinum drugs combined with radiotherapy in the treatment of small cell lung cancer].

OBJECTIVE: To compare the clinical efficacy of VP-16(etoposide) with VM-26(teniposide) both plus platinum drugs combined with radiotherapy in the treatment of patients with small cell lung cancer(SCLC). METHODS: Seventy-four cases of SCLC were studied retrospectively. Forty-three patients were treated with VP-16 + DDP + CTX or VP-16 + DDP, the other 31 patients were treated with VM-26 + DDP or VM-26 + Carboplatin. The treatment of both groups was combined with radiotherapy. RESULTS: There was no significant difference between VP-16 and VM-26 groups in response rate, 2-year-survival rate, and brain metastasis rate. But the blood toxicity was more serious in VM-26 group than in VP-16 group; 3-4 stage toxicity rate was 58.06% versus 27.91%. CONCLUSION: The results indicate that both VP-16 and VM-26 combined with platinum drugs were effective chemotherapy protocols. The authors suggest choosing VP-16 protocols as the first choice for previously untreated SCLC patients.

Adult↗

PubMed1998

[Cholesterol granuloma of the maxillary sinus: 2 cases report].

The paper firstly represents two cases of cholesterol granuloma of the maxillary sinus in China. The common symptoms of the disease include nasal obstruction and bone erosion in severe case. The disease is related to obstruction of the antral ostia, hemorrhage into polypoidal mucosal disease or cholesterol precipitation in the walls of antral cyst. A review of the literature on cholesterol granuloma suggests that poor ventilation in a closed space and long-standing inflammation with effusion or hemorrhage contribute to the formation of cholesterol granuloma. Long-lasting cure is achieved by radical maxillary sinusotomy which is the main therapeutic means.

Adult↗