Biomedical subjects

Jun Shen

Publications and source records attributed to Jun Shen.

71 records · Page 4Linked to original sources

PubMed2004

[Epidemiology and drug resistance of the pathogenic microbes in the complicated infection of hematological malignancies].

OBJECTIVE: To investigate the epidemiological characteristics and drug resistance profile of the infection in patients with hematological malignancies. METHODS: All the microbe strains isolated from the department of hematology in Ruijin hospital between 1998 and 2002 were collected for the assessment of antimicrobial susceptibility and the results were analysed by WHONET5 software. RESULTS: Out of the 536 strains isolated in the department of hematology, 230 (42.9%) were Gram positive and 301 (56.2%) Gram negative organisms. The first 6 strains of Gram (-) microbes in frequent order were Pseudomonas aeruginosa, Klebsiella pneumoniae, Enterobacter cloacae, Escherichia coli, Acinetobacter Baumannii and Stenotrophomonas (xantho) maltophi. The extended spectrum beta-lactamase (ESBLs) producing rates of Escherichia coli and Klebsiella pneumoniae were 27.3% and 33.3%, respectively. Methylcillin resistant coagulase negative staphylococcus (MRCNS) was the most prevalent Gram (+) bacteria in the complicated infection patients with hematological malignancies, which accounted for 88.5%. Carbapenems were most sensitive for all of the gram negative bacteria, with a drug resistance rate of 11.4 (5.0% approximately 15.8%) of imipenem. For ESBLs strains, carbapenems and cefapime were the best choice, with the resistance rate of 46.4% approximately 94.4% and 50.0% approximately 75.9%, respectively. The drug resistance rate of Acinetobacter Baumannii was 25.0% approximately 41.3% for the third generation cephalosporin, 22.7% for the fourth generation cephalosporin and 12.7% for imipenem. Pseudomonas aeruginosa was resistant to carbapenems, with a resistance rate of 12.7% of imipenem; however, it was more sensitive to the third generation cephalosporin. CONCLUSION: Antibiotics should be rationally administrated with more considerations to the characteristics of epidemiology and drug resistance profile of the microbes in the given department of hematology.

Bacterial Infections↗

PubMed2003

Induction of glutathione S-transferase placental form positive foci in liver and epithelial hyperplasia in urinary bladder, but no tumor development in male Fischer 344 rats treated with monomethylarsonic acid for 104 weeks.

The carcinogenicity of monomethylarsonic acid (MMA(V)), a major metabolite of inorganic arsenics in human and experimental animals, was investigated in male Fischer 344 rats. A total of 129 rats at 10 weeks of age were randomly divided into three groups and received drinking water containing MMA(V) at doses of 0 (Control), 50, and 200 ppm ad libitum for 104 weeks. No significant differences were found between the control and the MMA(V)-treated groups regarding clinical signs, mortality, hematological, and serum biochemistry findings. Quantitative analysis of glutathione S-transferase placental form (GST-P) positive foci in liver revealed a significant increase of numbers and areas in the 200 ppm MMA(V)-treated group. In the urinary bladder MMA(V) induced simple hyperplasia and significantly elevated the proliferating cell nuclear antigen (PCNA)-positive index in the urothelium. A variety of tumors developed in rats of all groups, including the controls, but all were histologically similar to those known to occur spontaneously in F344 rats and there were no significant differences among the groups. Thus, it could be concluded that, under the present experimental conditions, MMA(V) induced lesions in the liver and urinary bladder, but did not cause tumor development in male F344 rats even after 2 years exposure.

Administration, Oral↗

PubMed2003

Chemopreventive effect of JTE-522, a selective cyclooxygenase-2 inhibitor, on 1, 2-dimethylhydrazine-induced rat colon carcinogenesis.

Selective COX-2 inhibitors have been suggested to be an effective strategy in the prevention of colon cancer without the adverse side effects of non-selective, nonsteroid anti-inflammatory drugs. The present experiment was designed to assess the potential chemopreventive properties of JTE-522, a new selective cyclooxygenase-2 inhibitor, on the induction of 1,2-dimethylhydrazine (DMH)-induced colonic aberrant crypt foci (ACF), a marker of rat colon carcinogenesis. A total of 80 male F344 rats were treated with 3 or 10 mg/kg of body weight JTE-522 or vehicle by oral gavage five times weekly from the start of the experiment. One week later, rats received s.c. injections of saline or 20 mg/kg of body weight DMH once weekly for four successive weeks. At the end of 12 weeks after the start of experiment, all rats were sacrificed and colons were evaluated for ACF. 10 mg/kg JTE522 significantly suppressed the total ACF/colon. No inhibitory effect was observed in the 3 mg/kg JTE-522 treatment group. This result suggests that JTE-522 possesses chemopreventive activity against colon carcinogenesis.

1,2-Dimethylhydrazine↗

PubMed2003

Liver tumorigenicity of trimethylarsine oxide in male Fischer 344 rats--association with oxidative DNA damage and enhanced cell proliferation.

Arsenic is a notorious environmental toxicant known to be carcinogenic for the skin, lung and urinary bladder in human beings. The carcinogenicity of trimethylarsine oxide (TMAO), one organic metabolite of inorganic arsenics in humans and experimental animals, was investigated here in male Fischer 344 rats in a 2-year carcinogenicity test. TMAO was administered to a total of 129 male rats ad libitum at concentrations of 0 (Control), 50 or 200 p.p.m. in the drinking water. In animals that died or were killed from the 87th week until the end of 104th week, incidences of hepatocellular adenomas were 14.3, 23.8 and 35.6% in the 0, 50 and 200 p.p.m.-treated groups, respectively; the multiplicities were 0.21, 0.33 and 0.53. Both were significantly increased in the 200 p.p.m.-treated group. While a variety of other tumors developed in various organs, they were present in all groups, including the controls, and were histologically diagnosed as those known to occur spontaneously in F344 rats. To test the contribution of reactive oxygen species (ROS) to TMAO tumorigenicity in the liver, 8-hydroxydeoxyguanosine (8-OHdG) formation was assessed by high performance liquid chromatography. The 8-OHdG values for the 200 p.p.m. TMAO group were significantly higher than those for the control group. Furthermore, as assessed by the proliferating cell nuclear antigen index, cell proliferation in the normally appearing parenchyma was elevated by the TMAO treatment. These results indicate that TMAO exerts liver tumorigenicity with possible mechanistic roles for oxidative DNA damage and enhanced cell proliferation.

Animals↗

PubMed2003

Phenobarbital at low dose exerts hormesis in rat hepatocarcinogenesis by reducing oxidative DNA damage, altering cell proliferation, apoptosis and gene expression.

Our recent research indicated that phenobarbital (PB) may inhibit the development of N-diethylnitrosamine (DEN)-initiated pre-neoplastic lesions at low doses in a rat liver medium-term bioassay (Ito test), while high doses exhibit promoting activity. This raises the question of whether treatment with low doses of PB might reduce cancer risk. For clarification, male 6-week-old F344 rats were treated with PB at doses of 0, 2, 15 and 500 p.p.m. in the diet for 10 or 33 weeks after initiation of hepatocarcinogenesis with DEN. In a second, short-term experiment, animals were given PB at doses of 2, 4, 15, 60 and 500 p.p.m. for 8 days. Formation of glutathione S-transferase placental form (GST-P) positive foci and liver tumors was inhibited at 2 p.p.m. Generation of oxidative DNA damage marker, 8-hydroxy-2'-deoxyguanosine (8-OHdG), cellular proliferation within the areas of GST-P positive foci and apoptosis in background liver parenchyma were suppressed. Suppression of 8-OHdG formation by PB at low dose might be related to the enhanced mRNA expression of 8-OHdG repair enzyme, oxoguanine glycosylase 1 (Ogg1). Moreover, as detected by cDNA microarray analysis, PB treatment at low dose enhanced mRNA expression of glutamic acid decarboxylase (GAD65), an enzyme involved in the synthesis of gamma-aminobutyric acid (GABA), and suppressed MAP kinase p38 and other intracellular kinases gene expression. On the contrary, when PB was applied at a high dose, GST-P positive foci numbers and areas, tumor multiplicity, hydroxyl radicals and 8-OHdG levels were greatly elevated with the increase in CYP2B1/2 and CYP3A2 mRNA, protein, activity and gene expression of GST, nuclear tyrosine phosphatase, NADPH- cytochrome P-450 reductase and guanine nucleotide binding protein G(O) alpha subunit. These results indicate that PB exhibits hormetic effect on rat hepatocarcinogenesis initiated with DEN by differentially altering cell proliferation, apoptosis and oxidative DNA damage at high and low doses.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2003

Slice-selective J-coupled coherence transfer using symmetric linear phase pulses: applications to localized GABA spectroscopy.

Symmetric, linear phase, slice-selective RF pulses were analyzed theoretically for performing slice-selective coherence transfer. It was shown using numerical simulations of product operators that, when a prefocusing gradient of the same area as that of the refocusing gradient is added, these pulses become slice-selective universal rotator pulses, therefore, capable of performing slice-selective coherence transfer. As an example, a slice-selective universal rotator pulse based on a seven-lobe hamming-filtered sinc pulse was applied to in vivo single-shot simultaneous spectral editing and spatial localization of neurotransmitter GABA in the human brain.

Algorithms↗

PubMed2003

Effective normalization method for sample-position-dependence effect in photoacoustic spectrometry.

Sample position dependence effect in photoacoustic (PA) spectrometry has been reported by several scientists. This effect must be taken into account in a PA application that requires a quantitative theoretical treatment. In this work, we experimentally investigated PA signal magnitude varying with sample-to-window distance in an MTEC Model 300 Photoacoustic Detector, which has a fixed empty (gas) volume in addition to the sample-to-window-distance-dependent gas volume. An operative method was introduced to obtain the coefficient, which considered the sample-to-window distance and the additional gas volume. With this coefficient, the one-dimensional PA model, developed by Aamodt, Murphy, and Parker, can be employed to quantitatively process PA experimental data, no matter what the sample-to-window distance is. Quantitative measurements of thermal effusivities of two samples were performed to prove this effective normalization method.

Acoustics↗

PubMed2003

[Quantitative magnetic resonance (MR) imaging of bone marrow in leukemia].

BACKGROUND & OBJECTIVE: There were many studies on the relationship between magnetic resonance (MR) imaging of bone marrow and clinical laboratory variables of the patients with leukemia; however, few of them had separated lymphoid leukemia (LL) from myeloid leukemia (ML). The current study was designed to investigate the role of signal intensity ratio (SIR) of MR Imaging in the characteristic diagnosis and tumor burden evaluation in leukemia by separately measurement of spinal marrow SIR in LL and ML. METHODS: Spinal marrow in 20 LL patients and 10 ML patients in initial consultant were examined with MR imaging. The diagnosis of leukemia in all the patients was proved by iliac marrow cytological examination. MR imaging of spinal marrow was performed with 0.5T super-conducting system. T1-weighted imaging with spin-echotechniques and T2-weighted imaging with turbo spin-echo techniques were performed. The SIR of spinal marrow to spinal cord in leukemia was calculated on midline sagittal T1-weighted imaging. Meanwhile,peripheral blood routine examination and bone marrow cytological examination was performed. RESULTS: The SIR of spinal marrow in 20 LL patients and 10 ML patients were 0.72+/-0.11 and 0.73+/-0.11, respectively. There was no statistically significant difference between LL and ML(P=0.836). The SIR of spinal marrow in LL negatively correlated with the percentage of blast lymphocyte in marrow(r =-0.836,P= 0.000),while the SIR of spinal marrow in ML negatively correlated with the percentage of blast myelocyte in marrow (r=-0.673,P= 0.033). CONCLUSION: The SIR of spinal marrow is limited in the characteristic diagnosis of leukemia because of its inability to differential LL from ML. The SIR of spinal marrow can be used to evaluate tumor burden in leukemia.

Adolescent↗

PubMed2003

[Magnetic resonance imaging (MRI) findings of temporal lobe radiation encephalopathy].

BACKGROUND & OBJECTIVE: The imaging appearance of radiation encephalopathy (REP) was widely reported. However, there were few researches on imaging multiplicity of REP. The current study was designed to observe the morphological features of REP on magnetic resonance imaging(MRI) and to investigate its diagnostic value. METHODS: The MRI of 160 lesions with the diagnosis of temporal lobe REP on MRI was retrospectively analyzed in 104 patients with nasopharyngeal carcinoma (NPC). The MRI was performed after radiation therapy of NPC with an interval ranged from 8 months to 13 years. The imaging sequences included T1-weighted imaging and T2-weighted imaging additionally. T1-weighted imaging with injection of the contrast agent of Gd-DTPA was performed in 111 lesions and fluid attenuated inversion recovery (FLAIR) was obtained in 37 lesions, MR perfusion weighted imaging (PWI) was performed in 2 of them. RESULTS: Unilateral temporal lobe was involved in 48 cases of REP, bilateral temporal lobe in 56 cases of REP respectively, with totally 160 lesions founded. The REP in the white matter displayed hyper-intensity signal on T2-weighted imaging which could be homogenous, whereas area with heterogeneous hypo-intensity signal could be seen in 59 of them otherwise with hyper-intensity signal, and 91 lesions of white matter were associated with gray matter lesions with an appearance of hypo-intensity signal on T1-weighted imaging and hyper-intensity signal on T2-weighted imaging. In 111 lesions with the Gd-DTPA enhanced T1-weigthed imaging, 91 showed the enhancement of brain parencyma. Hemorrhage and hemosiderosis were found in 5 lesions of REP. CONCLUSION: REP in NPC has a multiplicity of the imaging features on MRI, in addition to the common involvement of white matter, including other relatively frequent findings, such as the involvement of gray matter, hemorrhage, hemosiderosis and blood-brain barrier destruction, those could be clearly revealed on MRI.

Adult↗

PubMed2002

Magnetic resonance spectroscopic approaches to studying neuronal: glial interactions.

In vivo magnetic resonance spectroscopy (MRS) is a noninvasive technique for the measurement of the concentration and synthesis of metabolites in the brain. Application of the state-of-the-art in vivo (13)C and (15)N MRS techniques to studying the synthesis of glutamate and glutamine has revealed that the glutamate-glutamine cycle between neurons and glia is a major metabolic flux, with a flux rate of 60%-80% relative to neuronal oxidative glucose metabolism in the resting human cerebral cortex. The MRS studies leading to the quantification of the glutamate-glutamine cycling flux are reviewed here. The advantages and limitations of different strategies are also discussed.

Animals↗

PubMed2002

Astroglial contribution to brain energy metabolism in humans revealed by 13C nuclear magnetic resonance spectroscopy: elucidation of the dominant pathway for neurotransmitter glutamate repletion and measurement of astrocytic oxidative metabolism.

Increasing evidence supports a crucial role for glial metabolism in maintaining proper synaptic function and in the etiology of neurological disease. However, the study of glial metabolism in humans has been hampered by the lack of noninvasive methods. To specifically measure the contribution of astroglia to brain energy metabolism in humans, we used a novel noninvasive nuclear magnetic resonance spectroscopic approach. We measured carbon 13 incorporation into brain glutamate and glutamine in eight volunteers during an intravenous infusion of [2-13C] acetate, which has been shown in animal models to be metabolized specifically in astroglia. Mathematical modeling of the three established pathways for neurotransmitter glutamate repletion indicates that the glutamate/glutamine neurotransmitter cycle between astroglia and neurons (0.32 +/- 0.07 micromol x gm(-1) x min(-1)) is the major pathway for neuronal glutamate repletion and that the astroglial TCA cycle flux (0.14 +/- 0.06 micromol x gm(-1) x min(-1)) accounts for approximately 14% of brain oxygen consumption. Up to 30% of the glutamine transferred to the neurons by the cycle may derive from replacement of oxidized glutamate by anaplerosis. The further application of this approach could potentially enlighten the role of astroglia in supporting brain glutamatergic activity and in neurological and psychiatric disease.

Acetates↗

PubMed2002

In vivo GABA editing using a novel doubly selective multiple quantum filter.

A novel multiple quantum filtering method is proposed that uses a doubly selective pulse termed Delays Alternating with Nutations for Tailored Excitation (DANTE) for multiple quantum preparation. This method selectively prepares GABA-3 and GABA-4 into a multiple quantum state and suppresses all other resonances at 3.0 ppm in each single scan. Phantom tests demonstrated excellent GABA signal retention and complete suppression of overlapping metabolites. It is shown using numerical simulations that overlapping macromolecules are suppressed because the frequency of the first upfield 2pi rotation of the doubly selective DANTE pulse coincides with that of the macromolecules at 1.72 ppm. Excellent suppression of overlapping macromolecules was demonstrated in vivo. Using this method the concentration of GABA in the occipital lobe of healthy volunteers was measured to be 1.21 +/- 0.28 micromol/mL (mean +/-SD, N = 9).

Adult↗

PubMed2002

Dynamic determination and possible mechanism of amino acid transmitter release from rat spinal dorsal horn induced by the venom and a neurotoxin (BmK I) of scorpion Buthus martensi Karsch.

In the present communication, we determined the dynamic release of amino acid transmitters from spinal dorsal horn induced by scorpion Buthus martensi Karsch (BmK) venom and a neurotoxin (BmK I). The results found that glutamate and aspartate release could be evoked significantly within the initial 30 min with the applied doses of either 0.05 and 0.01 mg BmK venom or 0.01 and 0.002 mg BmK I. However, gamma-aminobutyric acid (GABA) release could be largely evoked during the second 30 min by the venom, but not by BmK I. The result suggested that nociceptive afferent fibers could be activated to induce excitatory amino acid release from spinal dorsal horn by nociceptive factors such as BmK I, but the delayed release of GABA might be attributed to the modulating role of some antinociceptive components in the venom.

Animals↗

PubMed2002

[Magnetic resonance imaging manifestation of 500 patients with primary hepatic cell carcinoma].

BACKGROUND & OBJECTIVE: Magnetic resonance imaging (MRI) is one of the main imaging diagnostic methods for primary hepatic cell carcinoma. This study was designed to summarize the MRI manifestation and to evaluate Gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) and super paramagnetic iron oxide particles(SPIO) enhanced MRI in diagnosis of small hepatic carcinoma. MATERIALS & METHODS: Five hundreds patients diagnosed as primary hepatic cell carcinoma histologically were examined by MRI plain scan, plain scan + Gd-DTPA enhanced T1 weighted imaging, and plain scan + Gd-DTPA T1 weighted imaging + SPIO-enhanced heavy T2 weighted imaging was performed, respectively. RESULTS: In 500 patients, there were 65 (13.0%) small hepatic cell carcinoma, 81(16.2%) nodular lesions, 325 (65.0%) lump lesions; 29(5.8%) diffused lesions. 310(62%) patients were single lesion and the rest were multiple lesions. Twelve percent of the cases was associated with lymph nodes metastases, and 31.4% were complicated with vascular invasion. Diameter of the lesion was correlated positively to intro-hepatic metastases of the same or different lobe, the lymph nodes metastases and vascular invasion (P < 0.05). Totally 71 lesions were detected in the 65 cases with small hepatic carcinoma. Enhanced scan detected more lesions than plain scan (P < 0.05), and the lesions detected by Gd-DTPA + SPIO-enhanced scan were more than that by Gd-DTPA alone (P < 0.05). CONCLUSION: With the diameter of the lesion increase, the possibility of intro-hepatic metastases, lymph node metastases, and vascular invasion increased. For the MRI diagnosis of small HCC, enhanced scan especially Gd-DTPA + SPIO enhanced scan could detect more lesions than plain scan.

Adolescent↗

PubMed2002

[MRI diagnosis of tumor involving brachial plexus].

BACKGROUND & OBJECTIVE: The incidence rate of tumor involving brachial plexus was rare and its clinical diagnosis is difficult. Several foreign authors have reported that magnetic resonance imaging (MRI) is the best imaging diagnosis method. Howev, there was little report about this in China. This study was designed to investigate the diagnostic value of MRI in tumor involving brachial plexus. METHODS: The MRI manifestations in 13 patients with tumor involving brachial plexus (including 3 neurofibromatosis, 4 Pancoast's tumor, 6 metastatic tumor; 8 confirmed pathologically, 2 confirmed by biopsy, 3 neurofibromatosis confirmed clinically) were analyzed retrospectively. RESULTS: In 3 patients with neurofibromatosis, 2 cases showed growing along brachial plexus and represented spindle-shape; 1 cases showed growing crushing and encircling brachial plexus and represented ball-shape. There were middle or poor even signals on T1WI, and overt high and high-low mixed signals on T2WI (intense with even or uneven after enhancement). All 4 cases of Pancoast's tumor infiltrated brachial plexus. In 6 cases of metastatic tumor, 5 cases represented that localized bump encircled and infiltrated brachial plexus. 1 case represented that the tumor tissue effusively infiltrate brachial plexus. No special manifestation was shown on MRI of Pancoast's tumor and metastatic tumor. There were the similar or lower signals on T1WI, and high signals on T2WI (intense with even or uneven after enhancement). CONCLUSION: The coronal position of T1WI could clearly represent the relationship between brachial plexus and tumor, the involving extent of brachial plexus. Therefore, MRI is a effective imaging method for diagnosis of primary or secondary tumor involving brachial plexus.

Adolescent↗

PubMedDate not supplied

Lack of preventive efficacy of FK228, a histone deacetylase inhibitor, against N-butyl-N-(4-hydroxybutyl) nitrosamine-induced urinary bladder carcinogenesis in p53+/- and p53+/+ mice.

BACKGROUND: The efficacy of FK228, a histone deacetylase inhibitor that is currently under early clinical trials for cancer therapy, against N-butyl-N-(4-hydroxybutyl)- nitrosamine (BBN) -induced mouse urinary bladder carcinogenesis was examined. MATERIALS AND METHODS: Heterozygous p53-deficient (p53+/-) and wild-type (p53+/+) mice were given FK228 (0, 0.01 and 0.1 mg/kg i.p., 3 times/week, respectively) after 10 weeks of 0.05% BBN treatment, and were sacrificed at 22 and 24 weeks after the start, respectively. RESULTS: There was no significant difference in the incidence of urinary bladder tumors among groups in the p53+/- or p53+/+ mice, although the high dose of FK228 increased the p21WAF1 mRNA expression in urinary bladder cancers in animals of both genotypes. CONCLUSION: The present data indicate a lack of any inhibitory effects of FK228 on BBN-induced mouse urinary bladder carcinogenesis under the present conditions.

Animals↗

PubMedDate not supplied

Inhibition of azoxymethane-induced colon carcinogenesis in rats due to JTE-522, a selective cyclooxygenase-2 inhibitor.

Prostaglandin E2, which is produced by cyclooxygenase (COX) during arachidonic acid metabolism, is considered to be related to colon carcinogenesis and selective COX-2 inhibitors may be effective for chemoprevention without the adverse side effects of non-selective, nonsteroid anti-inflammatory drugs. Therefore, the influence of JTE-522 (4-(4-cyclohexyl-2-methyloxazol-5-yl)-2-fluorobenzensulfonamide), a selective COX-2 inhibitor, was examined in azoxymethane(AOM)-induced rat colon carcinogenesis. A total of 40 male F344 rats were randomly divided into two groups. Group 1 received diet containing 0.015% JTE-522 and group 2 the normal diet without supplement as a control group; one week later, all rats were administered axozymethane (AOM) s.c. at a dose of 15 mg/kg body weight once a week for 3 successive weeks. At the termination of the experiment (30 weeks after the start), the multiplicity of colon cancer in group 1 was significantly less than that of group 2. The proliferating cell nuclear antigen (PCNA) indices for non-neoplastic cells of the colon mucosa in group 1 were also lower. These data thus suggest that JTE-522 has chemopreventive potential against colon carcinogenesis with decrease of mucosal cell proliferation in rats.

Administration, Oral↗