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Biomedical subjects

Jun Cao

Publications and source records attributed to Jun Cao.

At least 73 records · Page 4Linked to original sources
PubMed2003

The stress experience dependent long-term depression disassociated with stress effect on spatial memory task.

Behavioral stress can either block or facilitate memory and affect the induction of long-term potentiation (LTP) and long-term depression (LTD). However, the relevance of the stress experience-dependent long-term depression (SLTD) to spatial memory task is unknown. Here we have investigated the effects of acute and sub-acute elevated platform (EP) and foot shock (FS) stress on LTD induction in CA1 region of the hippocampus of anesthetized rats and spatial memory in Morris water maze. We found that LTD was facilitated by acute EP stress, but not by sub-acute EP stress that may be due to the fast adaptation of the animals to this naturalistic mild stress. However, FS stress, an inadaptable strong stress, facilitated LTD induction both in acute and sub-acute treatment. In addition, with the same stress protocols, acute EP stress impaired spatial memory but the sub-acute EP stressed animals performed the spatial memory task as well as the controls, may due to the same reason of adaptation. However, acute FS stress slightly impaired learning but sub-acute FS even enhanced memory retrieval. Our results showed that SLTD was disassociated with the effect of stress on memory task but might be related to stress experience-dependent form of aberrant memory.

Adaptation, Biological↗
PubMed2003

Effect of complex amino acid imbalance on growth of tumor in tumor-bearing rats.

AIM: To investigate the effect of complex amino acid imbalance on the growth of tumor in tumor-bearing (TB) rats. METHODS: Sprague-Dawley (SD) rats underwent jejunostomy for nutritional support. A suspension of Walker-256 carcinosarcoma cells was subcutaneously inoculated. TB rats were randomly divided into groups A, B, C and D according to the formula of amino acids in enteral nutritional solutions, respectively. TB rats received jejunal feedings supplemented with balanced amino acids (group A), methionine-depleted amino acids (group B), valine-depleted amino acids (group C) and methionine- and valine-depleted complex amino acid imbalance (group D) for 10 days. Tumor volume, inhibitory rates of tumor, cell cycle and life span of TB rats were investigated. RESULTS: The G0/G1 ratio of tumor cells in group D (80.5 +/- 9.0)% was higher than that in groups A, B and C which was 67.0 +/- 5.1%, 78.9 +/- 8.5%, 69.2 +/- 6.2%, respectively (P<0.05). The ratio of S/G2M and PI in group D were lower than those in groups A, B and C. The inhibitory rate of tumor in groups B, C and D was 37.2%, 33.3% and 43.9%, respectively (P<0.05). The life span of TB rats in group D was significantly longer than that in groups B, C, and A. CONCLUSION: Methionine/valine-depleted amino acid imbalance can inhibit tumor growth. Complex amino acids of methionine and valine depleted imbalance have stronger inhibitory effects on tumor growth.

Amino Acids↗
PubMed2003

Influence of methionine/valine-depleted enteral nutrition on nucleic acid and protein metabolism in tumor-bearing rats.

AIM: To investigate the effects of methionine/valine-depleted enteral nutrition (EN) on RNA, DNA and protein metabolism in tumor-bearing (TB) rats. METHODS: Sprague-Dawlley (SD) rats underwent jejunostomy for nutritional support. A suspension of Walker-256 carcinosarcoma cells was subcutaneously inoculated. 48 TB rats were randomly divided in 4 groups: A, B, C and D. The TB rats had respectively received jejunal feedings supplemented with balanced amino acids, methionine-depleted, balanced amino acids and valine-depleted for 6 days before injection of 740 KBq (3)H- methionine/valine via jejunum. The (3)H incorporation rate of the radioactivity into RNA, DNA and proteins in tumor tissues at 0.5, 1, 2, 4 h postinjection of tracers was assessed with liquid scintillation counter. RESULTS: Incorporation of (3)H into proteins in groups B and D was (0.500+/-0.020) % to (3.670+/-0.110) % and (0.708+/-0.019) % to (3.813+/-0.076) % respectively, lower than in groups A ((0.659+/-0.055) % to (4.492+/-0.108) %) and C ((0.805+/-0.098) % to (4.180+/-0.018) %). Incorporation of (3)H into RNA, DNA in group B was (0.237+/-0.075) % and (0.231+/-0.052) % respectively, lower than in group A (P<0.01). There was no significant difference in uptake of (3)H by RNA and DNA between group C and D (P>0.05). CONCLUSION: Protein synthesis was inhibited by methionine/valine starvation in TB rats and nucleic acid synthesis was reduced after methionine depletion, thus resulting in suppression of tumor growth.

Amino Acids↗
PubMed2003

Toxicities and therapeutic effect of 5-fluorouracil controlled release implant on tumor-bearing rats.

AIM: To investigate the toxicities, biodistribution and anticancer effect of 5-fluorouracil controlled release implant (5-FUCI) on Walker 256 carcinosarcoma cells in Wistar rats. METHODS: Experiment 1: Wistar rats were randomly divided into three groups (27 rats per group). Blank implant was implanted in left lobe of the liver, and rats were treated with saline solution (in group A) or 5-fluorouracil (subcutaneous injection, group B). 5-FUCI was inserted in left lobe of the liver (group C). The gastrointestinal and hematological toxicities were observed and contents of element F in group C were assayed. Experiment 2: on day 6 after Walker-256 carcinosarcoma transplantation in left lobe of the liver, 5-FUCI was implanted in right lobe of the liver (group E) or left lobe (group F), and rats in control group (group D) were inserted blank implant. Tumor inhibition rate and survival time were investigated. RESULTS: 5-FUCI showed no obvious toxic effect, extraction of Evan's blue from gastrointestinal tissue was normal, the peripheral white blood cells and bone marrow nucleated cells were not reduced, compared with control group (P>0.05). Histological examination revealed that there were no visible changes in small intestinal mucosa, The concentration of 5-fluorouracil in left lobe of the liver was 9.84, 28, 34 times as much as those of right lobe of the liver, heart and kidney respectively after the implantation in group C. They kept a high level of fluorouracil in left lobe of the liver, ranging from (4.414+/-0.482) % to (7.800+/-0.804) %, for eight weeks. Survival days were 28.0+/-2.2, 30.0+/-3.2 and 38.7+/-6.7 d in group D, E and F, respectively. CONCLUSION: 5-FUCI shows no obvious toxicities to gastrointestinal tract and myelotoxicity. After implantation, it kept a high level of 5- fluorouracil in surrounding tissues of the implant for eight weeks. Its antitumor effect on Walker-256 carcinosarcoma is demonstrated.

Animals↗
PubMed2003

Relationship between nuclear morphometry, DNA content and resectability of pancreatic cancer.

AIM: To investigate the association of nuclear morphometry and DNA content with resectability of pancreatic cancer. METHODS: A total of 36 patients with pancreatic adenocarcinoma were divided into resectable group and unresectable group. The nuclear morphometry and DNA contents of tumor cells were analyzed by IBAS autoimagine analyzer from paraffin-embedded materials. Localization size, histological type and grade, and clinical stage of the tumor were evaluated. Factors influencing resectability of pancreatic cancer were investigated using stepwise regression analysis. RESULTS: Statistical significance was found in nuclear DNA content (integrated optical density, IOD) of tumor cells (1.64+/-0.41 vs 2.96+/-0.55), DNA ploidy, ages (46.5+/-5.3 years vs 58.6+/-0.7 years) and tumor volumes (298.1+/-101.5 cm(3) vs 634.7+/-512.5 cm(3)) in both groups (P<0.05), and no difference was found in the nuclear morphometry (P>0.05). The rates of diploid/tetraploid and aneuploid were 66.7 % and 33.3 % in resectable group respectively, and 38.9 % and 62.1 % in unresectable group, respectively (P<0.05). IOD (X(12)), ploidy status (X(12)) and clinical stage (X(3)) were radical resectable indicators with statistical significance. The regression equation for resectability was Y=-9.2053+3.5428X(12)+2.5390X(13)-2.3001X(3) (RR=0.8780, P<0.01). CONCLUSION: There is a high correlation between resectability of pancreatic cancers and their DNA contents, DNA ploidy status and clinical stage.

Adenocarcinoma↗
PubMed2003

[Evaluating the fate of gamma-HCH using fugacity model in Tianjin environment].

This study taking Tianjin as the study area calculated the concentration and transfer flux of gamma-HCH in all bulks using Matlab based on the assumption of steady state fugacity model. The calculated values agree well with the observed values, the concentrations of gamma-HCH in air, water, soil, sediment, fish, crop, and vegetable were 1.57 x 10(-11), 7.95 x 10(-7), 1.17 x 10(-4), 4.58 x 10(-4), 6.03 x 10(-4), 1.60 x 10(-4), 6.42 x 10(-5) mol/m3 respectively. The result indicated that the main source of gamma-HCH was agricultural application and wastewater from pesticide industries, the biggest bulk sinks were soil and sediment (accounting for 99% of total amount in the environment). Among all transfer processes deposition and diffusion on the water-sediment and air-soil interface were the primary, and mineralization was the key route for gamma-HCH to disappear in the environment.

China↗
PubMed2003

Set-up and preliminary performance of a digital radiology conference system.

OBJECTIVE: To investigate the set-up and preliminary performance of a digital radiology conference system and its characteristics. METHODS: The imaging system included a dual-screen image-text workstation with a Matrox G450 demonstration dual-head card, two multimedia projectors, a large screen, and a line-pair and grey scale test card. Patient information on radiology information system (RIS) and images on picture archiving and communication system (PACS) were fetched with GE Radworks software based on Intranet and PACS. The fetching velocity and resolution and grey scale of the images were measured. RESULTS: Patient information in the form of texts and images were demonstrated successfully on two screens with Matrox G450 demonstration dual-head card and switched rapidly between text-image two-screen and image two-screen. The image fetching velocity was fast, the resolution was high, and the grey scale was good. CONCLUSION: The digital conference radiology system is good, and should be popularized.

Audiovisual Aids↗
PubMed2003

[Multimedia fate modeling with spatial resolution for phenanthrene in Tianjin].

Behavior and fate of phenanthrene in various phases in Tianjin were calculated using a multimedia model with spatial resolution under steady-state assumption. Spatial variation of two parameters, namely soil organic carbon content and emission from fossil fuel combustion, were taken into consideration. Both soil and air phases were further divided into 3113 sub-compartments and 6226 equations in total were solved simultaneously under mass-balance assumption. A number of output parameters, therefore, were generated and were used for mapping of phenanthrene concentrations in soil and air, as well as transfer fluxes between compartments. The model was evaluated in two ways. 1. Comparison between the calculated and the observed average concentrations in bulk compartments, and 2. Comparison of spatial distribution of the calculated and the observed phenanthrene concentrations in surface soil. In both cases, the predicted results are in fair agreement with the independently measured values. As the results of the modeling, it was demonstrated that soil and sediment, especially the later, is the primary sink of phenanthrene in the area over 70% of the chemical accumulated in sediment. The spatial distribution pattern of phenanthrene in surface soil depends on content of soil organic matter which prevent the degradation of the material by bacteria. For distribution in ambient air, the dominant controlling factor is the emission.

Air↗
PubMed2003

[Response of an Arabidopsis mutant to elevated CO2 concentration].

The study on the response of a mutant and a wild-type of Arabidopsis to 660 microliters.L-1 CO2 and ambient CO2 showed that under elevated CO2, the stomatal numbers of the mutant increased, while those of the wild-type decreased. The chlorophyll content and NR (nitrate reductase) activity of the mutant increased, but those of the wild-type had no obvious response. The mutant was not reproductively mature after the continuous exposure to increased CO2 for five months. The results provided evidence of plant response to the changes of atmospheric CO2 concentration, and the clues to related studies on other plants.

Air↗
PubMed2002

[Comparison of ISE, ASV and FQ for complexation characterization of river water DOC with copper].

Condition stabilization constants of complexation between naturally occurring organic ligand in river water and copper were measured lgk and compared by using ISE, ASV and FQ methods. The measured lgk results were 2.29-6.47 by ISE, 2.61-6.91 by ASV, and 3.52-4.71 by FQ, respectively. The constants went up with the raise of pH, the decrease of copper content, and the increase of ligand concentration.

Copper↗
PubMed2002

Effect of chronic hypoxia on contents of urotensin II and its functional receptors in rat myocardium.

The cyclic peptide urotensin II (UII) has recently been cloned in mammals and reported to constrict rat pulmonary arteries potently. An enhanced maximal response was shown in rats exposed to chronic hypoxia. The aim of this study was to investigate changes in plasma and myocardial UII levels and its receptor sites in crude sarcolemma of ventricles from chronic hypoxic rats. We observed that rats exposed to chronic hypoxia for 4 weeks developed pulmonary hypertension and right ventricular hypertrophy. Compared with controls, the UII content in hypoxic rats was increased by 97.5% (45.24 +/- 7.1 vs. 22.9 +/- 3.24pg/mg protein, P < 0.01) in the right ventricle and 33.2% (24.89 +/- 0.99 vs. 18.68 +/- 2.04pg/mg protein, P < 0.01) in the left ventricle, respectively. However, there was no significant difference in plasma (27.44 +/- 3.11 vs. 27.82 +/- 5.57pg/ml, P > 0.05) and lung tissue levels (34.03 +/- 4.63 vs. 33.74 +/- 4.06 pg/ mg protein, P > 0.05) between the control and hypoxic groups. The time course of the binding of [125I]UII to crude ventricular sarcolemma was specific and time dependent. Scatchard plot analysis of the data demonstrated that the maximal number of specific binding sites (Bmax) in both the right and left ventricles was upregulated in the hypoxic group. Moreover, Bmax in the right ventricular specimens was upregulated to a greater extent than in the left ventricle (increased by 114% and 25% in the right and left ventricles, respectively, compared with control group, P < 0.01). In contrast, the UII binding affinity in right and left ventricular membranes from hypoxic rats was decreased (the dissociation constant Kd) increased by 20% and 33%, respectively compared with controls, P < 0.01). These results indicate that UII may act as an autocrine and/or paracrine hormone rather than as a circulating hormone, playing important roles in the development of ventricular hypertrophy induced by chronic hypoxia, and that the pathophysiological significance of UII in pulmonary and cardiovascular alteration induced by chronic hypoxia deserves further investigation.

Animals↗
PubMed2002

System-level responses of lake ecosystems to chemical stresses using exergy and structural exergy as ecological indicators.

This paper presents the system-level responses of experimental lake ecosystems to three chemical stresses (acidification, copper and pesticide contamination) using exergy and structural exergy as ecological indicators. The results indicate that the doses or toxicity of the three chemical stressors contributed to changes in both exergy and structural exergy. Remarkable changes in exergy and structural exergy occurred under acidic conditions and in the presence of Dursban, 24D-DMA, permethrin, bifenthrin, Carbaryl, TCP, PCP, trichlorethylene, benzene, and high doses of Cu, oil, and hexazinone. This seemed to indicate that the subject ecosystems were seriously contaminated by these chemical stressors. For low doses of Cu, oil, atrazine, HCBP, and hexazinone, exergy and structural exergy were either unchanged or only slightly changed, suggesting that the lake ecosystems were not significantly impacted by these chemical stressors. Discussion of the relationships between ecosystem-level changes and structural and functional changes in stressed lake ecosystems indicates that the above-mentioned ecosystem-level changes were in accordance with the changes in structure and function. The observed changes in exergy and structural exergy were also consistent with Odum's predictions of shortened food chains, reduced resource use efficiency, poor stability, low information, and high entropy in stressed aquatic ecosystems. The findings lead the authors to conclude that it is feasible for exergy and structural exergy to serve as ecological indicators when characterizing the system-level responses of experimental lake ecosystems to chemical stress. These results for experimental lake ecosystems would be extrapolated to actual lakes.

Animals↗
PubMed2002

A fragment constant QSAR model for evaluating the EC50 values of organic chemicals to Daphnia magna.

The quantitative relationship between the median effective concentration (EC50) of organic chemicals to Daphnia magna and the number of molecular fragments was investigated based on experimental EC50 values for 217 chemicals derived from the literature. A fragment constant model was developed based on a multivariate linear regression between the number of fragments and the logarithmically transformed reciprocal values of EC50. Functional correction factors were introduced into the model. The model was verified using an independent set of randomly selected data. The mean residual of the final model was 0.4 log-units. The robustness of the model was discussed based on the results of three jackknife tests.

Animals↗
PubMed2002

[Establishment of human immortalized oral epithelial cell line HIO615 induced by HPV16 E6 and E7].

OBJECTIVE: To establish an immortalized oral epithelial cell line. METHODS: Normal human oral epithelial cells were transfected with HPV16E6/E7 open reading frames using recombinant retroviral system pLXSN. Expression of HPV16E6 and E7 protein were tested by Western blot in three kinds of cells. To define cellular biological characterization of HPV16E6/E7 transfected cells, a series analysis were performed, including protraction of growth curve, HE staining, immunocytochemical staining and scanning electron microscope observation. The tumorigenicity was assessed by colony formation and transplanting the cells into nude mice. RESULTS: Human oral epithelial cells transfected with HPVE6/E7 has been in culture for over 18 months. The cell line was named HIO615. Western blot analysis showed HIO615 expressed HPV16 E6 and E7 protein. HIOC were positive for cytokeratin, tonofibril and desmosome as observed by scanning electron microscope. The number of large colonies of dense multilayer cells was low (0.77%). No tumor developed in nude mice injected subcutaneously with HIOEC. CONCLUSION: A human immortalized oral epithelial cell line induced by HPV16E6 and E7 has been successfully established.

Animals↗
PubMed2002

[Desorption of kaolin adsorbed copper in the fish gill microenvironment].

In order to investigate the bioavailability of kaolin adsorbed copper on gills of carpio, and to explain its possible mechanism in terms of speciation, exposure experiments with constant concentration of water soluble copper and increased concentration of kaolin adsorbed copper was carried on, and the speciation analyses was developed using MINTEQA2. The results of the exposure experiment indicated that expose to kaolin adsorbed copper would increase the metal accumulation in the fish gills. The shift of the copper speciation was demonstrated via chemical equilibrium calculation. To be specific, the kaolin adsorbed copper would be partially desorbed in the fish gill microenvironment in the alkaline water environment.

Adsorption↗
PubMed2002

Study on the correlation between tongue size and openbite.

OBJECTIVE: To investigate the correlation between tongue size and openbite. METHODS: The tongue size of the openbite patients and the subjects with normal occlusion was measured by B-type ultrasonic imaging respectively. The tongue size of the openbite patients and the subjects with normal occlusion was compared. RESULTS: The tongue size in openbite group was larger than in normal occlusion group. The difference was statistically significant. CONCLUSIONS: Tongue size was related to the openbite.

Adolescent↗
PubMed2002

[Influence of HPV16 on expression of Rb, p16 and cyclin D1 in oral epithelial cell].

OBJECTIVE: To investigate the role of HPV16E6 and E7 during the transformation of oral epithelial cells. METHODS: An human immortalized oral epithelial cell line (HIOEC) was established by transfecting HPV16E6, E7 open reading frames using recombinant retroviral system plxsn to human normal oral epithelial cells. Expression of HPV16E6, E7, Rb, P16 and Cycin D1 were analyzed by Western blot in HIOEC and human normal oral epithelial cells. Formation of complex of HPV16E7 and Rb were analyzed by Immunoprecipitation-western blot. Human normal oral epithelial cells and the oral epithelial cells transfected with plxsn were used as control groups. RESULTS: HIOEC expressed HPV16 E6 and E7; HIOEC expressed both hyperphosphorylated and underphosphorylated Rb while oral epithelial cells in two control groups only expressed hyperphosphorylated Rb. HPV16 E7 formed complex with underphosphorylated Rb; the level of P16 and Cyclin D1 had no remarkable change. CONCLUSIONS: HPV16E7 plays an important role in the immortalization of oral epithelial cells induced by HPV16.

Blotting, Western↗