Biomedical subjects

X Jin

Publications and source records attributed to X Jin.

At least 55 records · Page 3Linked to original sources

PubMed2001

[Analysis of the risk factors and drug resistance of lower respiratory tract infection by Flavobacteria].

OBJECTIVE: To investigate risk factors of 26 cases with lower respiratory tract infection caused by Flavobacteria and its antimicrobial susceptibility in vitro. METHODS: Retrospective study of the clinical materials of 26 cases of lower respiratory tract infection caused by Flavobacteria. Antimicrobial susceptibility (MIC) was determined with the method of agar dilution. RESULTS: All of 26 cases suffered from underlying diseases, among them malignant tumors were most common (31%) illness. 50% of the cases were mixed infections. Risk factors of infections were application of multiple antibiotics (81%), host immune suppression (77%), invasive manasements (31%), and prolonged hospitalization. No specific clinical manifestations and chest X-ray appearance revealed. Isolates were highly resistant to most of antimicrobial agents. Ciprofloxacin, trimethoprim-sulfamethoxazole and piperacillin are the most sensitive agents. CONCLUSIONS: Lower respiratory tract infection caused by Flavobacteria developed most commonly in patients who suffered from various underlying diseases, immunodeficiency, and longtime antibiotic overuse. Clinical isolates were highly resistant to most kinds of antimicrobial agents.

Adolescent↗

PubMed2001

[Detection of serum free insulin-like growth factor 1 in patients with chronic viral hepatitis].

OBJECTIVE: To evaluate the serum free insulin-like growth factor 1 (IGF-1) level and its relation with the severity and prognosis in patients with chronic viral hepatitis, liver cirrhosis and severe chronic hepatitis. METHODS: Serum free IGF-1 was detected by ELISA in 43 patients with chronic viral hepatitis, 20 with liver cirrhosis and 12 with chronic severe hepatitis. RESULTS: Serum free IGF-1 was significantly decreased in patients with liver cirrhosis and severe chronic hepatitis. Five patients with chronic severe hepatitis whose serum free IGF-1 was lower than 0.2 ng/l died during follow-up. Four patients whose serum free IGF-1 above 0.3 ng/l survived. Serum free IGF-1 was significantly reduced in patients with albumin lower than 30 g/l. CONCLUSIONS: Serum free IGF-1 is decreased in patients with liver cirrhosis and severe chronic hepatitis and it can predict the prognosis of patients with severe chronic hepatitis.

Adult↗

PubMed2001

[Hepatocyte targeted DNA carrier L-PEI: the lactosylated polyethyleneimine and transfection in vitro].

BACKGROUND: To develop a hepatocyte targeted DNA carrier for expression of IFN or delivery of antiviral antisense neucleic acid into hapatocytes. METHODS: The hepatocyte targeted lactosylated polyethleneimine (L-PEI) was prepared through reductive amination of PEI with lactose. The in vitro transfection experiment was conducted and the stability of the DNA complex in rat serum was evaluated. RESULTS: L-PEI can effectively deliver luciferase gene into the galactose receptor positive Huh-7 cells. The transfection can be specifically inhibited by the synthesized ligand-lactosaminated BSA. The complex of DNA/L-PEI is stable in rat serum with only little degradation observed after 30 minutes, while free DNA was destroyed completely. CONCLUSIONS: L-PEI can be used as an specific and efficient DNA carrier.

Animals↗

PubMed2001

[Expression of transforming growth factor beta(TGF-beta) subtypes in oral squamous cell carcinoma].

OBJECTIVE: The objective of this study was to determine the expression of transforming growth factor beta (TGF-beta) subtypes and their relationship with the mechanisms of squamous cell carcinoma (OSCC) growth. METHODS: Totally 40 cases of surgical specimens of OSCC resected between 1998 and 2000 and 20 cases of normal human oral mucosa were investigated. Strepto-adridinibiotin complex (SABC) immunohistochemical staining was used to analyze the expression of TGF-beta protein subtypes and their relations with clinical prognosis of OSCC. RESULTS: Semi-quantitative analysis revealed that the subtypes 1, 2 and 3 of TGF-beta protein could be found in OSCC cells and normal oral epithelial cells, however the intensity of protein expression was different. Comparing with those in normal oral mucosa epithelial cells, the subtypes 1 and 2 of TGF-beta were over-expressed in OSCC cells. The over-expression of subtypes 1 and 2 of TGF-beta protein were associated with their pathological grades, clinical stages and neck lymph node metastasis (P < 0.05), whilst the subtype 3 protein of TGF-beta was not. CONCLUSION: It will be useful to detect the expression of TGF-beta subtypes in OSCC, as the subtypes 1 and 2 of TGF-beta may play an important role in OSCC growth and metastasis.

Adult↗

PubMed2001

[Production and detection of monoclonal anti-idiotype antibodies against Vibrio anguillarum].

Vibrio anguillarum is the pathogenic bacteria of Vibriosis, which is an infectious disease found in various fish species. Seven monoclonal anti-idiotype antibodies(mAb2) were raised against mAb1 4A6. Identification of subgroup showed that 1H5, 1D1, 2B12 and 2F12 belonged to IgG2b, 2H12 and 1H12 to IgG2a and 1E10 to IgG3. The titers of these mAb2 ascites were 1 x 10(-4)-1 x 10(-6). The capacity of the mAb2 to inhibit the binding between mAb1 and antigen was investigated with the competitive inhibition ELISA. The results showed that 1D1, 1E10 1H5 and 2H12 mAb2 were able to inhibit this binding. Another experiment demonstrated that four mAb2(1D1, 1E10, 1H5 and 2H12) might induce Balb/c mice to produce Ab3 and these Ab3 competed the same antigen epitopes with Ab1. These results indicate that mAb2(1D1, 1E10, 1H5 and 2H12) are likely to represent internal image of antigen and belong to Ab2 beta. They might be employed to induce antibodies against pathogenic epitopes of V. anguillarum in vivo so as to gave the safe and effective vaccine.

Animals↗

PubMed2001

[Study on voltage-sensitive current of spiral ganglion cells in mice organ of Corti culture].

OBJECTIVE: To investigate the property of voltage-sensitive current in cochlear spiral ganglion cells of the C57BL/10J mice, an inbred strain which develops early onset hearing loss. METHODS: Organotypic cultures of organ of Corti were prepared from neonatal mice 0-5 days of age. Whole-cell current and voltage clamp techniques were used to study Na+, K+ and Ca2+ currents of the spiral ganglion cells in culture. RESULTS: Cultures were maintained for 8-48 hours before use. Ganglion cells were identified first through their anatomical positions and finally through fast negative Na+ current. Spontaneous action potentials were recorded from some ganglion cells (4 out of 39). When present, spontaneous rates were around 20 spikes/sec, and might be as high as 135 spikes/sec. The mean resting potential was (-55 +/- 5) mV (n = 39). Under voltage clamp conditions, transient inward currents (negative) and outward (positive), steady-state voltage-dependent currents were recorded in normal HBSS. Rapid inward currents were totally blocked by 300 nM TTX applied locally to the culture. Inward currents recovered quickly after TTX wash out suggesting that the transient inward current was carried by Na+. The mean maximum amplitude of Na+ current was (-2.0 +/- 1.1) nA (n = 39) recorded in HBSS. Adding TEA (10 mmol/L) and 4-AP (0.15 mmol/L) to the bath solution or replacing K+ with Ca+ in the pipette solution partly blocked the sustained outward current. This suggests that the outward current was carried by K+. The mean maximum amplitude of K+ was (3.0 +/- 1.3) nA (n = 39) with 140 mM K+ in the pipette. Inward Ca2+ current was recorded in Ba2+ solution which mean peak amplitude was (-1.0 +/- 0.7) nA (n = 20). Ca2+ currents were reversibly blocked by 100 microM Cd2+. CONCLUSION: Whole cell recordings from spiral ganglion neurons can be obtained from organotypic cultures of the organ of Corti. Fast Na+ current, sustained K+ current and L-type Ca2+ current were recorded in the spiral ganglion cells cultured for 1-2 days. Whole cell recording showed that cochlea spiral ganglion cells can generate spontaneous action potential one day after birth and the firing rates could reach levels equal to those recorded in vivo.

Action Potentials↗

PubMed2001

[Study on the determination of iodine by inductively coupled plasma atomic emission spectrometry].

A new method for determining iodine had been developed in ICP-AES. An oxidant, NaNO2 and a sample containing iodine ion were mixed in the PHD hydroid generation device, the producing iodine molecules were nebulized in nebulizer and then the iodine gas came into troch directly. The problem that the intensity of iodine decreases with the increase of time was solved. It was found that NaNO2 decreased the effect of Cl- in the low acidity. A detection limit of 14 ng.mL-1 was obtained and the RSD of the measurement for 2 micrograms.mL-1 of iodine was 1.2% (n = 10). The average recoveries of iodine were 99.44%. The method was applied to the determination of salt and seawater.

Iodides↗

PubMed2000

A modified p53 overcomes mdm2-mediated oncogenic transformation: a potential cancer therapeutic agent.

The antiproliferative activities of wild-type (wt) p53 are inhibited by mdm2 (murine double minute2) oncogene product. We tested growth suppression activity of p53 14/19, an engineered p53 variant, which does not bind mdm2 and is completely resistant to the inhibition by mdm2. p53 14/19, unlike wt p53, suppressed the growth of cancer cells that contain amplified mdm2 oncogene efficiently by direct DNA transfection or adenovirus-mediated gene transfer. In addition, p53 14/19 also inhibited the growth of several different cancer cell lines expressing low levels of mdm2 oncogene product as efficiently as wt p53. We further examined the antioncogenic potencies of p53 14/19 in the rat embryo fibroblast cotransformation assay. Addition of wt p53 failed to cause any significant decrease in ras plus mdm2 foci counts. In contrast, cotransfection of p53 14/19 with ras and mdm2 significantly reduced foci number. In similar experiments, cotransfection of wt p53 or 14/19 p53 resulted in significant inhibition of oncogenic transformation in rat embryo fibroblast mediated by an activated ras plus c-myc, adenovirus E1A, or human papillomavirus E7 oncogenes. Therefore, these results suggest that p53 14/19 modified tumor suppressor gene may be a promising therapeutic agent for human cancers that express abnormally high levels of mdm2 oncogene product.

Adenoviridae↗

PubMed2000

Brownian Dynamics Simulation of Film Formation of Mixed Polymer Latex in the Water Evaporation Stage.

Brownian dynamics simulations of the filming process of a mixed polymer latex in the water evaporation stage were performed in order to explore the effect of surface potential on latex particle packing and distribution at a temperature far below the glass transitions of polymers in bulk. Polymer latex particles are modeled as spheres that interact via DLVO potential with various surface charge densities for emulsifier-free emulsion polymerized particles and dispersion polymerized particles. It is found that the distribution of modeled poly(methyl methacrylate) and polystyrene latex particles in the finally formed film exhibits a noticeable dependence of surface potentials of latex particles. When the difference of the surface potentials between binary mixed latex particles is small, the particles distribute randomly. In contrast, when the difference of the surface potentials between binary mixed latex particles is large, heterocoagulation occurs and the polymer latex in which the repulsive electrostatic potential is weak will form clusters in the film. The results are in agreement with laser confocal fluorescence microscopy observations of fluorescent dye labeled poly(methyl methacrylate) and polystyrene mixed latex films. The correlation between latex particles increases with increasing repulsive electrostatic potential, and the spatial order can be obtained at the end of the water evaporation stage. Copyright 2000 Academic Press.

Journal Article↗

PubMed2000

Effects of in vivo CD8(+) T cell depletion on virus replication in rhesus macaques immunized with a live, attenuated simian immunodeficiency virus vaccine.

The role of CD8(+) T lymphocytes in controlling replication of live, attenuated simian immunodeficiency virus (SIV) was investigated as part of a vaccine study to examine the correlates of protection in the SIV/rhesus macaque model. Rhesus macaques immunized for >2 yr with nef-deleted SIV (SIVmac239Deltanef) and protected from challenge with pathogenic SIVmac251 were treated with anti-CD8 antibody (OKT8F) to deplete CD8(+) T cells in vivo. The effects of CD8 depletion on viral load were measured using a novel quantitative assay based on real-time polymerase chain reaction using molecular beacons. This assay allows simultaneous detection of both the vaccine strain and the challenge virus in the same sample, enabling direct quantification of changes in each viral population. Our results show that CD8(+) T cells were depleted within 1 h after administration of OKT8F, and were reduced by as much as 99% in the peripheral blood. CD8(+) T cell depletion was associated with a 1-2 log increase in SIVmac239Deltanef plasma viremia. Control of SIVmac239Deltanef replication was temporally associated with the recovery of CD8(+) T cells between days 8 and 10. The challenge virus, SIVmac251, was not detectable in either the plasma or lymph nodes after depletion of CD8(+) T cells. Overall, our results indicate that CD8(+) T cells play an important role in controlling replication of live, attenuated SIV in vivo.

Animals↗

PubMed2000

Identification of subdominant cytotoxic T lymphocyte epitopes encoded by autologous HIV type 1 sequences, using dendritic cell stimulation and computer-driven algorithm.

Conventional analysis of the cytotoxic T lymphocyte (CTL) response to HIV-1 may underestimate the true breadth of CTL epitopes recognized. This underestimation could be due to several reasons, including (1) the use of laboratory-adapted stains of HIV or consensus sequences, which would lead to the identification of only highly conserved epitopes, (2) the use of EBV-transformed B cells (B-LCLs) and vaccinia virus constructs in standard assays that may obscure low level CTL responses due to high EBV or vaccinia reactivity, and (3) relatively insensitive assays wherein PBMCs instead of professional APCs are used to stimulate CTL responses. To address these problems, we first identified an immunodominant HLA-B7-restricted CTL epitope, by standard cloning methods, in a long-term nonprogressor (LTNP). To determine whether the patient had CTLs specific for autologous viral sequences other than the dominant epitope, proviral DNA was cloned and sequenced. A matrix-based epitope algorithm (EpiMatrix) was used to identify the top 2% of peptides from the viral sequences with the highest likelihood of binding to HLA-B7. These 55 peptides were synthesized and tested for HLA-B7 binding in a T2/B7 cell line; 10 peptides were able to stabilize HLA-B7 on the cell surface. By using peptide-pulsed autologous dendritic cells as a more sensitive method of CTL stimulation, we found three additional subdominant CTL epitopes.

Algorithms↗

PubMed2000

Validation of biomarkers in humans exposed to benzene: urine metabolites.

BACKGROUND: The present study was conducted among Chinese workers employed in glue- and shoe-making factories who had an average daily personal benzene exposure of 31+/-26 ppm (mean+/-SD). The metabolites monitored were S-phenylmercapturic acid (S-PMA), trans, trans-muconic acid (t,t-MA), hydroquinone (HQ), catechol (CAT), 1,2, 4-trihydroxybenzene (benzene triol, BT), and phenol. METHODS: S-PMA, t,t-MA, HQ, CAT, and BT were quantified by HPLC-tandem mass spectrometry. Phenol was measured by GC-MS. RESULTS: Levels of benzene metabolites (except BT) measured in urine samples collected from exposed workers at the end of workshift were significantly higher than those measured in unexposed subjects (P < 0.0001). The large increases in urinary metabolites from before to after work strongly correlated with benzene exposure. Concentrations of these metabolites in urine samples collected from exposed workers before work were also significantly higher than those from unexposed subjects. The half-lives of S-PMA, t,t-MA, HQ, CAT, and phenol were estimated from a time course study to be 12.8, 13.7, 12.7, 15.0, and 16.3 h, respectively. CONCLUSIONS: All metabolites, except BT, are good markers for benzene exposure at the observed levels; however, due to their high background, HQ, CAT, and phenol may not distinguish unexposed subjects from workers exposed to benzene at low ambient levels. S-PMA and t,t-MA are the most sensitive markers for low level benzene exposure.

Acetylcysteine↗

PubMed2000

Global stability analysis in delayed Hopfield neural network models.

In this paper, without assuming the boundedness, monotonicity and differentiability of the activation functions, we present new conditions ensuring existence, uniqueness, and global asymptotical stability of the equilibrium point of Hopfield neural network models with fixed time delays or distributed time delays. The results are applicable to both symmetric and nonsymmetric interconnection matrices, and all continuous nonmonotonic neuron activation functions.

Algorithms↗

PubMed2000

Nitric oxide: a physiological mediator of the type 2 (AT2) angiotensin receptor.

Virtually all of the biological actions of angiotensin II (ANG II) have been thought to be mediated by the type 1 (AT1) angiotensin receptor and the function of the type 2 (AT2) receptor is unknown. We now describe a novel physiological action of ANG II to release nitric oxide (NO) mediated by the AT2 receptor in both the kidney and gastrointestinal tract. We present an integrated model for a counter-regulatory protective action of the AT2 receptor mediated by nitric oxide. In the kidney, ANG II at the AT2 receptor stimulates a vasodilator cascade of bradykinin (BK), NO and cyclic GMP which is tonically activated only during conditions of increased ANG II, such as sodium depletion. In the absence of the AT2 receptor, pressor and antinatriuretic hypersensitivity to ANG II is associated with BK and NO deficiency. In angiotensin-dependent hypertension, the hypotensive effect at AT1 receptor blockade is due at least in part to AT2 receptor stimulation and consequent increased activity of the vasodilator cascade. In the gastrointestinal tract, physiological quantities of ANG II stimulate the AT2 receptor releasing NO and cGMP leading to increased sodium and water absorption. In conclusion, NO is an important physiological mediator of ANG II at the AT2 receptor.

Absorption↗

PubMed2000

High frequency of cytomegalovirus-specific cytotoxic T-effector cells in HLA-A*0201-positive subjects during multiple viral coinfections.

How the cellular immune response copes with diverse antigenic competition is poorly understood. Responses of virus-specific cytotoxic T lymphocytes (CTL) were examined longitudinally in an individual coinfected with human immunodeficiency virus type 1 (HIV-1), Epstein-Barr virus (EBV), and cytomegalovirus (CMV). CTL responses to all 3 viruses were quantified by limiting dilution analysis and staining with HLA-A*0201 tetrameric complexes folded with HIV-1, EBV, and CMV peptides. A predominance of CMV-pp65-specific CTL was found, with a much lower frequency of CTL to HIV-1 Gag and Pol and to EBV-BMLF1 and LMP2. The high frequency of CMV-specific CTL, compared with HIV-1- and EBV-specific CTL, was confirmed in an additional 16 HLA-A*0201-positive virus-coinfected subjects. Therefore, the human immune system can mount CTL responses to multiple viral antigens simultaneously, albeit with different strengths.

Adult↗

PubMed2000

End-tidal carbon dioxide as a noninvasive indicator of cardiac index during circulatory shock.

OBJECTIVE: To document the relationships between cardiac index and end-tidal carbon dioxide tension (PetCO2 during diverse low-flow states of circulatory shock. DESIGN: Randomized, prospective, controlled studies on animal models of hemorrhagic, septic, and cardiogenic shock. SETTING: University-affiliated research laboratory. SUBJECTS: Sixteen anesthetized domestic pigs weighing 35-45 kg. INTERVENTIONS: Hemorrhagic shock was induced in five pigs by bleeding followed by reinfusion of shed blood. Septic shock was induced in five pigs by infusion of live Escherichia coli. Cardiogenic shock followed an interval of global myocardial ischemia after inducing and reversing ventricular fibrillation in six pigs. MEASUREMENTS AND MAIN RESULTS: PetCO2 was continuously measured. Cardiac index was measured intermittently by using conventional thermodilution techniques. Cardiac index was correlated with PetCO2 by polynomial regression and Bland-Altman analyses. PetCO2 was highly correlated with cardiac index during hemorrhagic shock (r2 = .69, p < .01), septic shock (r2 = .65, p < .01), and cardiogenic shock (r2 = .81, p < .01). PetCO2 predicted thermodilution cardiac index with bias of -11+/-27 (+/-2 SD) mL/min/kg during hemorrhagic shock, 1.3+/-20.4 (+/- 2 SD) mL/min/kg during septic shock, and -1+/-12 (+/-2 SD) mL/min/kg during cardiogenic shock. CONCLUSIONS: Cardiac output and PetCO2 were highly related in diverse experimental models of circulatory shock in which cardiac output was reduced by >40% of baseline values. Therefore, measurement of PetCO2 is a noninvasive alternative for continuous assessment of cardiac output during low-flow circulatory shock states of diverse causes.

Animals↗

PubMed2000

Targeted disruption of the mPer3 gene: subtle effects on circadian clock function.

Neurons in the mammalian suprachiasmatic nucleus (SCN) contain a cell-autonomous circadian clock that is based on a transcriptional-translational feedback loop. The basic helix-loop-helix-PAS proteins CLOCK and BMAL1 are positive regulators and drive the expression of the negative regulators CRY1 and CRY2, as well as PER1, PER2, and PER3. To assess the role of mouse PER3 (mPER3) in the circadian timing system, we generated mice with a targeted disruption of the mPer3 gene. Western blot analysis confirmed the absence of mPER3-immunoreactive proteins in mice homozygous for the targeted allele. mPer1, mPer2, mCry1, and Bmal1 RNA rhythms in the SCN did not differ between mPER3-deficient and wild-type mice. Rhythmic expression of mPer1 and mPer2 RNAs in skeletal muscle also did not differ between mPER3-deficient and wild-type mice. mPer3 transcripts were rhythmically expressed in the SCN and skeletal muscle of mice homozygous for the targeted allele, but the level of expression of the mutant transcript was lower than that in wild-type controls. Locomotor activity rhythms in mPER3-deficient mice were grossly normal, but the circadian cycle length was significantly (0.5 h) shorter than that in controls. The results demonstrate that mPer3 is not necessary for circadian rhythms in mice.

ARNTL Transcription Factors↗

PubMed2000

Genetic characterization of rebounding HIV-1 after cessation of highly active antiretroviral therapy.

Despite prolonged treatment with highly active antiretroviral therapy (HAART), infectious HIV-1 continues to replicate and to reside latently in resting memory CD4(+) T lymphocytes, creating a major obstacle to HIV-1 eradication. It is therefore not surprising to observe a prompt viral rebound after discontinuation of HAART. The nature of the rebounding virus, however, remains undefined. We now report on the genetic characterization of rebounding viruses in eight patients in whom plasma viremia was undetectable throughout about 3 years of HAART. Taking advantage of the extensive length polymorphism in HIV-1 env, we found that in five patients who did not show HIV-1 replication during treatment, the rebound virus was identical to those isolated from the latent reservoir. In three other patients, two of whom had been free of plasma viremia but had showed some residual viral replication, the rebound virus was genetically different from the latent reservoir virus, corresponding instead to minor viral variants detected during the course of treatment in lymphoid tissues. We conclude that in cases with apparent complete HIV-1 suppression by HAART, viral rebound after cessation of therapy could have originated from the activation of virus from the latent reservoir. In patients with incomplete suppression by chemotherapy, however, the viral rebound is likely triggered by ongoing, low-level replication of HIV-1, perhaps occurring in lymphoid tissues.

Adult↗