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Biomedical subjects

J Cao

Publications and source records attributed to J Cao.

At least 37 records · Page 2Linked to original sources
PubMed2004

Polycyclic aromatic hydrocarbons (PAHs) in agricultural soil and vegetables from Tianjin.

Several types of vegetables were collected from two contaminated sites in Tianjin, China. The bulk soil and the rhizosphere soil samples were also collected from the same plots. Sixteen PAHs in the samples were measured. The total concentrations of PAH16 in the bulk soil from the two sites were 1.08 and 6.25 microg/g, respectively, with similar pattern. The concentrations of PAH16 and individual compounds in the rhizosphere were significantly higher than those in the bulk soil with mean values of 2.25 and 7.82 microg/g for the two sites, respectively. The contents of both total and dissolved organic matter in the rhizosphere were also higher than those in the bulk soil. Almost all PAH compounds studied were detected in both roots and aerial parts of the vegetables studied. Abundance of higher molecular weight PAHs in vegetable, however, was lower than that in soil. Concentrations of PAH16 in vegetable were higher than those reported in the literature for other areas. It appears that agricultural soils and vegetables in Tianjin, especially those from the site located immediately next to an urban district and irrigated with wastewater for several decades, are severely contaminated by PAHs. Among the eight types of vegetable studied, the highest concentration of PAHs was found in cauliflower. By average, the concentration of PAH16 in the aerial part of vegetables was 6.5 times higher as that in vegetable root, suggesting that foliar uptake is the primary transfer pathway of PAHs from environment to vegetables.

China↗
PubMed2004

Residues of hexachlorocyclohexane isomers and their distribution characteristics in soils in the Tianjin area, China.

Hexachlorocyclohexane (HCH) has a history of use in China. This paper presents the results of an investigation of HCH residue isomers and their distribution characteristics in soils near Tianjin, China. One hundred eighty-eight soil samples were collected from the Tianjin area. Four HCH isomers-alpha-HCH, beta-HCH, gamma-HCH, and delta-HCH-were detected using gas chromatography for all samples. Concentrations of the sum HCH ranged from 1.3 to 1095 ng g(-1), among which beta-HCH accounted for 52.5%. In addition, residues of HCH within Tianjin's urban areas were found to be higher. No significant differences were found between the residues of HCH in soils from waste irrigation areas and those in other areas. Total organic carbon content was determined to impact the residue levels of HCH in soils, while pH value and clay content were not related to concentrations of HCH. In general, all HCH isomers in soil samples had abnormally high residue levels, possibly the result of continuous use of HCH in this area.

China↗
PubMed2004

The effect of pH, ion strength and reactant content on the complexation of Cu2+ by various natural organic ligands from water and soil in Hong Kong.

The complexation constants for copper associated with different natural organic ligands, including dissolved organic carbon (DOC) extracted from water, water soluble organic carbon (WSOC), fulvic acid (FA) and humic acid (HA) from soil, were determined and then compared based on discrete single site model. Both ion-selective electrode (ISE) and anodic stripping voltammetry were used to determine the content of free copper ions, while the relative number of complexation sites was estimated using a fluorescence quenching (FQ) at the same time. ISE proved to be the most applicable technique when the concentration of copper was above 10(-7) moll(-1). The logk values for two WSOC sample sites (Song Ziyuan and Xin Niangtan) were 4.64 and 4.66; higher than both the DOC and HA values yet lower than the FA values, which were unusually high due to unavoidable pollution from the cation exchange resin used during the purification process. Binding affinities between the copper ions and the organic ligands obtained from streams in Yong Wei (DOC) and Song Ziyuan (WSOC) were influenced by pH, ion strength, and reactant concentration. Values for logk increased with increases in pH (ion strength of 0.1 N). At pH 4, the logk values decreased with increases in the supporting electrolyte concentration and total copper ion additions.

Benzopyrans↗
PubMed2004

Level and distribution of DDT in surface soils from Tianjin, China.

One hundred and eighty eight surface soil samples were collected from the Tianjin area to study the contamination of DDT and its metabolites. Measurements were taken for p,p'-DDE, p,p'-DDD, p,p'-DDT, o,p'-DDE, o,p'-DDD and o,p'-DDT for all samples. The results indicated that p,p'-DDT and p,p'-DDE were the predominant contaminant compounds in the surface soil samples, with mean concentrations of 27.5 and 18.8 ng g(-1) respectively. No significant differences in DDT concentrations were found between the soils from wastewater treated irrigated areas and other areas, suggesting that wastewater irrigation is not an important source of DDT in the area. However, the spatial distribution of soil DDTs levels in the area did correlate well with early direct application rates of pesticides. In addition, both pH level and organic carbon content are also known factors affecting the level of DDT and its metabolites. Although it was assumed that the use of these chemicals was banned in the early 1980s, the current concentration levels appear to be too high to be mere residuals after 20 years degradation.

Agriculture↗
PubMed2004

Evaluation of factors influencing root-induced changes of copper fractionation in rhizosphere of a calcareous soil.

Major factors influencing the root-induced copper fractionation changes within the rhizosphere of maize, wheat, pea, and soybean seedlings were evaluated using a contaminated calcareous soil. The effects of acidification, alkalization, and introduction of root exudates were investigated by addition of acid, alkaline and root exudates from solution cultures, prior to incubation and copper fractionation. Raw and sterilized soils were compared for changes of copper fractionation in the rhizosphere using rhizoboxes with maize, wheat, pea and soybean seedlings. The results indicated that the general trend in considerable changes was similar among the plant species studied. The rhizosphere experienced a depletion of carbonate associated and organic bound copper along with an accumulation of exchangeable and Fe-Mn oxide bound copper. The resulting significant influence of root exudates on copper fractionation appears to have been produced through complexation rather than acidification or alkalization. The increase in exchangeable copper in rhizosphere was strengthened by microorganisms.

Copper↗
PubMed2004

Human papillomavirus type 16 and 18 DNA in oral squamous cell carcinoma and normal mucosa.

The aim of this study was to ascertain the prevalence of HPV 16/18 DNA in oral squamous cell carcinoma (OSCC) vs. normal oral mucosa, and to correlate the virologic data with other factors obtained from the patients' records. One hundred and thirteen paraffin embedded tissue samples (73 OSCC and 40 normal oral mucosa) were studied using HPV type specific primer-mediated polymerase chain reaction (PCR). Seventy-four per cent (54/73) of OSCC and 55% (22/44) of normal oral mucosa were positive for HPV 16/18 DNA. Statistical analysis indicated there was a significant difference between HPV16/18 positive OSCC vs. normal oral mucosa (P=0.040), and that age (<60 years) and gender (male) were correlated with the presence of HPV16/18 in the tumour. No significant association was found between the presence of HPV and other risk factors, including tobacco use, alcohol use, tumour location, histologic grade or TNM staging. We found a significant association of HPV16/18 with oral squamous cell carcinoma. Also, HPV16/18 is a co-factor in oral carcinogenesis, particularly in male patients and patients under the sixth decade. In addition, we found that HPV infection is a common event in the normal oral mucosa.

Adult↗
PubMed2004

Involvement of NF-kappaB and c-myc signaling pathways in the apoptosis of HL-60 cells induced by alkaloids of Tripterygium hypoglaucum (levl.) Hutch.

Tripterygium hypoglaucum (levl.) Hutch (Celastraceae) (THH) root is a Chinese medicinal herb commonly used for treating autoimmune diseases. In the present study, alkaloids of THH were prepared and their cytotoxicity against the HL-60 cell was investigated. THH-induced apoptosis was observed using flow cytometry, confocal fluorescence microscope, and DNA laddering and caspase assays. The molecular mechanism involved in the induction of HL-60 cell apoptosis by THH alkaloids was examined using cDNA microarrays containing 3000 human genes derived from a leukocyte cDNA library. Sixteen genes were identified to be differentially expressed in HL-60 cells upon THH treatment. Several genes related to the NF-kappaB signaling pathway and cell apoptosis (such as NFKBIB, PRG1 and B2M) were up-regulated. In addition, c-myc binding protein and apoptosis-related cysteine proteases caspase-3 and caspase-8 were also regulated. The changes in c-Myc RNA expression and c-myc protein level were further confirmed by RT-PCR and Western blot analysis. The results demonstrated that THH alkaloids induced apoptosis of HL-60 cells though c-myc and NF-kappaB signaling pathways.

Antineoplastic Agents, Phytogenic↗
PubMed2004

Sample purification for analysis of organochlorine pesticides in sediment and fish muscle.

The methods of sample purification for determinations of organochlorine pesticides (OCPs) in sediment and fish muscle were investigated in this study. A two-step procedure with preliminary cleanup and florisil column fraction was adopted. The working conditions of florisil column were firstly optimized. As to preliminary cleanup, liquid-liquid extraction by mixture of dimethyl formamide (DMF) and hexane and sulphonation by concentrated sulfuric acid were applied respectively and compared for the studied samples. The results indicated that liquid-liquid distribution could effectively separate lipids from fish muscle extracts, while failed in elimination of chlorophyll extracted from the relicts of hydrophytes in the sediment sample. In view of the sample appearance and clarity of gas chromatogram, sulphonation was more suitable to purify the sediment sample, however, the recoveries of the spiked standards were poor. The use of eluting solvent with stronger polarity could improve the corresponding recoveries significantly. Due to complete loss of Dieldrin, Endrin, and Endrin aldehyde after sulphonation, this pretreatment was improper to the three components. Sulfur, as the particular disturbing element in sediment, could be removed sufficiently by addition of activated copper powder. The relevant detection limits of the selected methods for OCPs in the studied substrates were also provided.

Animals↗
PubMed2003

Transgene expression in broccoli (Brassica oleracea var. italica) clones propagated in vitro via leaf explants.

We have developed an efficient protocol for the in vitro propagation of transgenic broccoli plants using leaf explants as starting material. A high frequency of shoot formation from leaf explants was obtained on Murashige and Skoog medium containing benzyladenine (BA, 5 mg/l) and naphthaleneacetic acid (0.5 mg/l). Frequent subcultures of existing shoots and shoot clusters to medium containing only BA (2 mg/l) promoted rapid shoot multiplication. The use of a 1:1 mixture of Agargel and Gelrite in the rooting medium increased the number of healthy roots per rooted plant. Applying this protocol, we obtained thousands of clonal rooted plantlets within 6 months from a transgenic broccoli plant carrying the cry1Ac and cry1C genes from Bacillus thuringiensis associated with kanamycin and hygromycin selectable markers, respectively. Thirty randomly selected clones that had been propagated for 1 year on medium containing kanamycin (50 mg/l) all showed resistance to both kanamycin and hygromycin. Genomic DNA and total soluble proteins were isolated from 16 of these clones. Polymerase chain reaction analysis indicated that the cry1Ac and cry1C genes were both maintained. ELISA assays showed that all of the clones produced a high level of Cry1Ac protein similar to the original transgenic plant; however, most clones had significantly lower levels of Cry1C protein than the original plant. This variation indicates that it is important to evaluate transgene expression in transgenic clones propagated long-term in vitro. In vitro propagation starting from leaf explants was also successful with other transgenic and non-transgenic Brassica oleracea materials, including broccoli, cauliflower, and collard.

Adenine↗
PubMed2003

Identification and expression of human CD81 gene on murine NIH/3T3 cell membrane.

The human CD81 (hCD81) molecule has been identified as a putative receptor for hepatitis C virus (HCV). In this study, eukaryotic expression vector pCDM8-hCD81 containing hCD81 cDNA and pSV2neo helper plasmid was used to cotransfect with lipofectamine into murine fibroblast cell line NIH/3T3 to establish an hCD81-expressing cell line. Resistant cell clones were obtained 20 days after the selection with neomycin (600 micro/ml) and then cultured as monoclones. The expression of the transfected hCD81 gene in the cells was verified by RT-PCR and flow cytometry analyses. One of the selected cell clones showed obvious expression of hCD81 and was named NIH/3T3-hCD81. Competitive inhibition tests indicated that the binding of monoclonal anti-hCD81 (JS-81) to NIH/3T3-hCD81 cells was inhibited by recombinant HCV E2 protein, suggesting that the expressed hCD81 molecules on NIH/3T3-hCD81 cells maintain natural conformation of binding to HCV E2. The transfected NIH/3T3-hCD81 cells should be of great potential value in studies on HCV attachment and onset of infection.

3T3 Cells↗
PubMed2003

Changes of copper speciation in maize rhizosphere soil.

Chemical forms of copper in the rhizosphere and bulk soil of maize were investigated using rhizobox cultivation and sequential extraction techniques. The copper accumulations were also determined. The results demonstrated that there were continuous changes in copper fractionation within the maize rhizosphere. Initially, the amount of exchangeable copper increased before dropping below the initial level after 40 days or so. Carbonate associated copper followed a similar trend of change, but with a slower pace than the exchangeable copper. The increase in carbonate associated copper only become evident after 30 days, with the net loss occurring after 60 days. There were also initial increases in oxide bound copper as well as decreases in the organic matter associated copper, both followed by a turnover after 40-50 days. The accumulation of copper in the maize plant was found to be biomass dependent. The amount of accumulated copper absorbed in the plant material exceeded the initial quantity of the exchangeable copper in the soil, revealing a transformation from less bioavailable to more bioavailable fractions. During cultivation, decreases in redox potential and increases in pH, dissolved organic carbon (DOC), and microbial activity in the maize rhizosphere were observed. The change in copper speciation may result from root-induced changes in DOC, redox potential, and microbial activity in the rhizosphere.

Agriculture↗
PubMed2003

The tree shrews: adjuncts and alternatives to primates as models for biomedical research.

The tree shrews are non-rodent, primate-like, small animals. There is increasing interest in using them to establish animal models for medical and biological research. This review focuses on the use of the tree shrews in in vivo studies on viral hepatitis, hepatocellular carcinoma (HCC), myopia, and psychosocial stress. Because of the susceptibility of the tree shrews (Tupaia belangeri) and their hepatocytes to infection with human hepatitis B virus (HBV) in vivo and in vitro, these animals have been used to establish human hepatitis virus-induced hepatitis and human HBV- and aflatoxin B1-associated HCC models. As these animals are phylogenetically close to primates in evolution and have a well-developed visual system and color vision in some species, they have been utilized to establish myopia models. Because dramatic behavioral, physiological, and neuroendocrine changes in subordinate male tree shrews are similar to those observed in depressed human patients, the tree shrews have been successfully employed to experimentally study psychosocial stress. However, the tree shrews holds significant promise as research models and great use could be made of these animals in biomedical research.

Animals↗
PubMed2003

Medium scale spatial structures of Polycyclic Aromatic Hydrocarbons in the topsoil of Tianjin area.

The spatial distribution patterns of Polycyclic Aromatic Hydrocarbons (PAHs) in soil are important to regional environmental assessment. In this paper, the spatial structural features of sixteen prior PAH compounds in the topsoil of Tianjin area, as well as soil properties, were studied. Results shown that medium scale spatial autocorrelations were well revealed. Spherical models with sills could be used to fit all experimental variograms. The spatial structures of PAHs contents demonstrated significant anisotropy. Air precipitation caused by the combustion of coal was the key factor in the formation of the spatial structural patterns of PAHs in the topsoil of Tianjin area.

China↗
PubMed2003

Ontogeny and specificities of mucosal and blood human immunodeficiency virus type 1-specific CD8(+) cytotoxic T lymphocytes.

Induction of adaptive immunity to human immunodeficiency virus type 1 (HIV-1) at the mucosal site of transmission is poorly understood but crucial in devising strategies to control and prevent infection. To gain further understanding of HIV-1-specific T-cell mucosal immunity, we established HIV-1-specific CD8(+) cytotoxic T-lymphocyte (CTL) cell lines and clones from the blood, cervix, rectum, and semen of 12 HIV-1-infected individuals and compared their specificities, cytolytic function, and T-cell receptor (TCR) clonotypes. Blood and mucosal CD8(+) CTL had common HIV-1 epitope specificities and major histocompatibility complex restriction patterns. Moreover, both systemic and mucosal CTL lysed targets with similar efficiency, primarily through the perforin-dependent pathway in in vitro studies. Sequence analysis of the TCRbeta VDJ region revealed in some cases identical HIV-1-specific CTL clones in different compartments in the same HIV-1-infected individual. These results clearly establish that a subset of blood and mucosal HIV-1-specific CTL can have a common origin and can traffic between anatomically distinct compartments. Thus, these effectors can provide immune surveillance at the mucosa, where rapid responses are needed to contain HIV-1 infection.

Cervix Uteri↗
PubMed2003

Both stress experience and age determine the impairment or enhancement effect of stress on spatial memory retrieval.

It has been documented that stress or glucocorticoids have conflicting effects on memory under different conditions. However, it is not fully understood why stress can either impair or enhance memory. Here, we have examined the performance of six age groups of Wistar rats in a water maze spatial task to evaluate the effects of stress under different conditions. We found that the impairment or enhancement effect of an 'elevated platform' (EP) stress on memory was dependent on previous stress experience and on age. EP stress impaired memory retrieval in water maze naive animals, but enhanced rather than impaired memory retrieval in young water maze stress-experienced animals. Furthermore, exogenously applied corticosterone or foot shock stress before water maze training prevented the impairment of memory retrieval that should be induced by treatment with corticosterone or foot shock before the 'probe trial'. Again, memory retrieval was enhanced in young animals under these conditions, and this enhancement can be prevented by the glucocorticoid receptor antagonist RU 38486. Thus, glucocorticoid receptor activation not only induced impairment of memory but also increased the capacity of young animals to overcome a later stress. The present findings suggest that the effect of stress on memory can be switched from impairment to enhancement dependent on both stress experience and age.

Aging↗
PubMed2002

Copper speciation and accumulation in the gill microenvironment of carp ( Cyprinus carpio) in the presence of kaolin particles.

Carp were exposed to copper adsorbed on kaolin particles at various concentrations (0-2.4 mg/L), and net accumulation due to elevated adsorbed copper in the surrounding water was observed. Copper speciation in the water and fish gill microenvironment was modeled in the presence and absence of kaolin using a chemical speciation program (MINTEQA2). The adsorption affinity constants of kaolin for copper at various pH values used in the speciation calculations were experimentally determined, and the quantitative relationship between the affinity constant and pH was modeled. Copper accumulations in fish gills exposed to kaolin-adsorbed copper was then observed. The results indicate that desorption occurred in the fish gill microenvironment due to both mucus competition of copper and slight increase in water pH. Furthermore, the available copper species increased as a result of desorption, causing a net accumulation of Cu by the gills.

Adsorption↗
PubMed2002

Determination of PAHs in wastewater irrigated agricultural soil using accelerated solvent extraction.

A procedure was developed for determination of 16 polycyclic aromatic hydrocarbons (PAHs) in heavily contaminated paddy soil from wastewater irrigated farmland near Tianjin. The sample was distilled with accelerated solvent extraction (ASE), purified by a silica gel column, and measured with GC/MS. The optimal conditions for the distillation were at 140 degrees C (1500 psi) with a 1:1 mixture of dichloromethane and acetone for 5 min. Application of cyclohexane for extract transfer improved the recovery when the ASE extraction was followed by a silica gel cleanup procedure. Recoveries from the method for 16 PAHs ranged from 57-140% with the coefficients of variation of the results ranging from 0.35% to 5.75%. The total 16 PAHs in a composite sample collected from a wastewater irrigated paddy field near Tianjin was 3.90 mg/kg.

China↗