Biomedical subjects

Yong Cai

Publications and source records attributed to Yong Cai.

At least 37 records · Page 2Linked to original sources

PubMed2005

Famine, social disruption, and involuntary fetal loss: evidence from Chinese survey data.

Relying on half a million pregnancy histories collected from Chinese women in the late 1980s, we studied nearly a quarter century of self-reported miscarriages and stillbirths in China. Our results suggest that these two forms of involuntary fetal loss are affected not only by biological and demographic factors, such as the mother's age, pregnancy order, and pregnancy history, but also by the mother's social characteristics and the larger social environment. In this article, we focus on how two social and economic crises--the Great Leap Forward famine and the Cultural Revolution--resulted in elevated risks of miscarriage and stillbirth in the Chinese population.

Abortion, Spontaneous↗

PubMed2005

Chloroquine-mediated radiosensitization is due to the destabilization of the lysosomal membrane and subsequent induction of cell death by necrosis.

The anti-malarial drug chloroquine (CQ) is also thought to be a potential radiation sensitizer. To gain a better understanding of how the lysomotropic CQ can potentiate the effects of ionizing radiation, we investigated the effects of CQ on lysosomal and mitochondrial membrane stability, the subcellular localization of ceramide, plasma membrane permeability, and the mode of cell death in response to irradiation. We found that CQ accumulated in the lysosomes and thus lysosomal volumes increased. As a result, both the lysosomal and plasma membranes were destabilized. After 7 Gy irradiation, most ceramide was associated with the lysosomes in the cells treated with CQ but not in the CQ-untreated control. The elevated levels of ceramide in the lysosomes of the CQ-treated cells appeared to further destabilize the lysosomal and plasma membranes of the cell. Both CQ-treated and -untreated cells had approximately the same rate of cell death by apoptosis after 7 Gy irradiation (P > 0.05, ns). However, in contrast to the CQ-untreated control, the CQ-treated cells underwent massive cell death by necrosis at 24-48 h after irradiation (P < 0.05). Taken together, our data support the idea that the increase in cytotoxic effects by the combination of CQ and radiation is due to radiation-mediated apoptosis and CQ-mediated necrosis.

Apoptosis↗

PubMed2004

Arsenic speciation of solvent-extracted leachate from new and weathered CCA-treated wood.

For the past 60 yr, chromate-copper-arsenate (CCA) has been used to pressure-treat millions of cubic meters of wood in the United States for the construction of many outdoor structures. Leaching of arsenic from these structures is a possible health concern as there exists the potential for soil and groundwater contamination. While previous studies have focused on total arsenic concentrations leaching from CCA-treated wood, information pertaining to the speciation of arsenic leached is limited. Since arsenic toxicity is dependent upon speciation, the objective of this study was to identify and quantify arsenic species leaching from new and weathered CCA-treated wood and CCA-treated wood ash. Solvent-extraction experiments were carried out by subjecting the treated wood and the ash to solvents of varying pH values, solvents defined in the EPA's Synthetic Precipitation Leaching Procedure (SPLP) and Toxicity Characteristic Leaching Procedure (TCLP), rainwater, deionized water, and seawater. The generated leachates were analyzed for inorganic As(III) and As(V) and the organoarsenic species, monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA), using high-performance liquid chromatography followed by hydride generation and atomic fluorescence spectrometry (HPLC-HG-AFS). Only the inorganic species were detected in any of the wood leachates; no organoarsenic species were found. Inorganic As(V) was the major detectable species leaching from both new and weathered wood. The weathered wood leached relatively more overall arsenic and was attributed to increased inorganic As(III) leaching. The greater presence of As(III) in the weathered wood samples as compared to the new wood samples may be due to natural chemical and biological transformations during the weathering process. CCA-treated wood ash leached more arsenic than unburned wood using the SPLP and TCLP, and ash samples leached more inorganic As(III) than the unburned counterparts. Increased leaching was due to higher concentrations of arsenic within the ash and to the conversion of some As(V) to As(III) during combustion.

Arsenates↗

PubMed2004

Identification of Elongin C and Skp1 sequences that determine Cullin selection.

The multiprotein von Hippel-Lindau (VHL) tumor suppressor and Skp1-Cul1-F-box protein (SCF) complexes belong to families of structurally related E3 ubiquitin ligases. In the VHL ubiquitin ligase, the VHL protein serves as the substrate recognition subunit, which is linked by the adaptor protein Elongin C to a heterodimeric Cul2/Rbx1 module that activates ubiquitylation of target proteins by the E2 ubiquitin-conjugating enzyme Ubc5. In SCF ubiquitin ligases, F-box proteins serve as substrate recognition subunits, which are linked by the Elongin C-like adaptor protein Skp1 to a Cul1/Rbx1 module that activates ubiquitylation of target proteins, in most cases by the E2 Cdc34. In this report, we investigate the functions of the Elongin C and Skp1 proteins in reconstitution of VHL and SCF ubiquitin ligases. We identify Elongin C and Skp1 structural elements responsible for selective interaction with their cognate Cullin/Rbx1 modules. In addition, using altered specificity Elongin C and F-box protein mutants, we investigate models for the mechanism underlying E2 selection by VHL and SCF ubiquitin ligases. Our findings provide evidence that E2 selection by VHL and SCF ubiquitin ligases is determined not solely by the Cullin/Rbx1 module, the target protein, or the integrity of the substrate recognition subunit but by yet to be elucidated features of these macromolecular complexes.

Amino Acid Sequence↗

PubMed2004

Arsenic complexes in the arsenic hyperaccumulator Pteris vittata (Chinese brake fern).

Pteris vittata (Chinese brake fern), the first reported arsenic (As) hyperaccumulating plant, can be potentially applied in the phytoremediation As-contaminated sites. Understanding the mechanisms of As tolerance and detoxification in this plant is critical to further enhance its capability of As hyperaccumulation. In this study, an unknown As species, other than arsenite (AsIII) or arsenate (AsV) was found in leaflets by using anion-exchange chromatography-hydride generation-atomic fluorescence spectroscopy and size-exclusion chromatography-atomic fluorescence spectrometry. The chromatographic behavior of this unknown As species and its stability suggest that it is likely an As complex. Although phytochelatin with two subunits (PC2) was the only major thiol in P. vittata under As exposure, this unknown As complex was unlikely to be an AsIII-PC2 complex by comparison of their chromatographic behaviors, stability at different pHs and charge states. The complex is sensitive to temperature and metal ions, but relatively insensitive to pH. In buffer solution of pH 5.9, it is present in a neutral form.

Arsenicals↗

PubMed2004

A set of consensus mammalian mediator subunits identified by multidimensional protein identification technology.

The Mediator is a multiprotein transcriptional coactivator that is expressed ubiquitously in eukaryotes from yeast to mammals and is required for induction of RNA polymerase II (pol II) transcription by DNA binding transcription factors. In the work described here, we exploit multidimensional protein identification technology (MudPIT) to carry out a proteomic analysis of the subunit composition of the mammalian Mediator complex. By comparing MudPIT data sets obtained from six independent Mediator preparations immunoaffinity purified through their Nut2 (MED10), Med25 (MED9), Intersex (MED29), LCMR1 (MED19), AK007855 (MED28), or CRSP70 (MED26) subunits, we identify a set of consensus mammalian Mediator subunits. In addition, we identify as Mediator-associated proteins the CDK8-like cyclin-dependent kinase CDK11 and the TRAP240-like KIAA1025 protein (MED13L), which is mutated in patients with the congenital heart defect transposition of the great arteries (TGA).

Adaptor Proteins, Signal Transducing↗

PubMed2004

Low molecular weight thiols in arsenic hyperaccumulator Pteris vittata upon exposure to arsenic and other trace elements.

Low molecular weight thiol-containing compounds have been reported to play an important role in metal detoxification and accumulation in some higher plants. The formation of these low molecular weight thiols in the recently discovered arsenic hyperaccumulator, Chinese Brake fern (Pteris vittata) upon exposure to arsenic and other trace metals was investigated. In addition to cysteine and glutathione, an unidentified thiol was observed in the plants exposed to arsenic, which was not found in the control. The concentration of the unidentified thiol showed a very strong and positive correlation with arsenic concentration in the leaflets. The unidentified thiol was low in rachises and undetectable in the roots for As-treated plants. Total and acid-soluble thiols were also measured and the results indicated that arsenic mainly stimulated the synthesis of acid-soluble thiol in Chinese Brake. The investigations of other trace elements (Cd, Cu, Cr, Zn, Pb, Hg, and Se) showed that these elements were not accumulated in Chinese Brake to high levels and the synthesis of the unidentified thiol in the plant was not observed. Our study suggests that the unidentified thiol was induced specifically by arsenic and the distribution patterns of the unidentified thiol and arsenic in the plant were consistent, indicating that the synthesis of this compound was related to As exposure.

Arsenic↗

PubMed2004

Thiol synthesis and arsenic hyperaccumulation in Pteris vittata (Chinese brake fern).

Pteris vittata (Chinese brake fern) has potential for phytoremediation of As-contaminated sites. In this study, the synthesis of total thiols and acid-soluble thiols in P. vittata was investigated under arsenic exposure. The strong and positive correlation between As concentration and acid-soluble thiols in plant leaflets suggests that acid-soluble thiols may play a role in As detoxification. A major As-induced thiol was purified and characterized. A molecular ion (M + 1) of 540 m/z suggests that the thiol was a phytochelatin (PC) with two base units (PC(2)). However, the ratios of acid-soluble thiols to As in leaflets exposed to As ranged from 0.012 to 0.026, suggesting that only a very small part of As is complexed by PC(2). PCs could play a minor detoxification role in this hyperaccumulator. A PC-independent mechanism appears to be mainly involved in As tolerance, while PC-dependent detoxification seems to be a supplement.

Arsenic↗

PubMed2004

[A review of basic statistics concepts,research design and statistical analysis methods].

Statistics is a methodology involving a great number of statistical methods. It results in confusion of many clinicians and researchers while they are meditating on how to analyze the collected data in their studies, selecting an appropriate statistical method from all. In fact, the statistical methods are closely correlated to the research design and the data types. Therefore only with a full comprehension of the design methods and the data types can we figure out a simple and practical means from diverse statistical analysis methods. Through the systematic illustration in this review, several statistical concepts, data types, design methods, and the proper way of explaining results with statistical tables and graphs will be demonstrated elaborately. It intends to help the clinicians and researchers select appropriate statistical methods and furthermore, interpret the statistical outcomes accurately in their research.

Humans↗

PubMed2004

[A review of statistical analysis methods in measurement data].

Measurement data, which is obtained by measuring the size of numeric value, is consisted of numerical variables. In clinic research, the collected data covers quite of numerical variables. Composed of those numerical variables, the measurement data has to be correspondingly analyzed in the special statistical methods in the light of their design methods. The statistical methods of measurement data include descriptive statistics and inferential statistics. Descriptive statistics is mainly used to describe the distribution laws and the characters/features of the data. For instance, when measuring the central tendency and dispersion tendency of the data, methods such as calculating the mean and the standard deviation can be considered. Inferential statistics is mainly employed to estimate the confidence limit such as estimating the 95% confidence interval and to have the hypothesis testing in the example of having t test and analysis of variance. By highlighting the specific statistical methods of measurement data, this review intends to help the clinicians and researchers select correct statistical methods in accordance with measurement data.

Data Interpretation, Statistical↗

PubMed2004

[A review of statistical analysis methods in measurement data].

Enumeration data is consisted of categorical variable. It is obtained by counting the frequency of the inhomogeneous data. In clinical research, the collected data cover quite of categorical variables. Composed of those categorical variables, the enumeration data had to be correspondingly analyzed with special statistical methods on the ground of their design methods. The statistical methods of measurement data include descriptive statistics and inferential statistics. Descriptive statistics is mainly used to measure the relative number such as rate, proportion and ratio. Inferential statistics is mainly employed to estimate the confidence limit such as estimating the 95% confidence interval of rate and to have the hypothesis testing in the example of having chi-square test etc. By highlighting the specific statistical methods of enumeration data, this review intends to help the clinicians and researchers select correct statistical methods in accordance with enumeration data.

Data Interpretation, Statistical↗

PubMed2004

[Survival analysis--the method used to analyze the follow-up data].

In clinical research, the collected data covers a kind of special data that named follow-up data. However, long time's follow-up is necessary when to evaluate the effect of certain drugs or operations on the patients. During this process, various kinds of outcome and different follow-up times will be found among patients. Survival analysis is a kind of statistical methods that connect outcome with survival time and co-analyze them. This statistical method is used to analyze completed data and uncompleted data at the same time, which can make the best use of the information in medical research to evaluate and compare the follow-up data more exactly. This review introduces the basic principle and method of survival analysis.

Data Interpretation, Statistical↗

PubMed2004

Anergic cells induced by the blockade of CD40-CD154 and CD28-B7 costimulatory pathways act as potent immunoregulatory cells in vitro and vivo.

BACKGROUND: This study was to evaluate whether anergic cells induced by the blockade of CD40-CD154 and CD28-B7 costimulatory pathways can act as potent immunoregulatory cells in vitro and prolong cardiac allograft survival after adoptive transfer. METHODS: Anergic cells were induced in vitro by the addition of anti-CD154 and anti-CD80 monoclonal antibodies (mAbs) to primary MLR (mixed lymphocyte reaction) consisting of BALB/c as responder and C3H as stimulator. Anergic cells were added to a newly formed MLR in assessing the regulatory capacity and antigen specificity of anergic cells. The ability of anergic cells to respond to antigen and/or exogenous recombinant mouse interleukin-2 (rmIL-2) was tested. For in vivo studies, anergic cells were intravenously injected into 3.0-Gy gamma-irradiated BALB/c mice immediately after heterotopic abdominal cardiac transplantation. To prolong allograft survival, recipient mice injected with anergic cells received rapamycin therapy [1 mg.day(-1).kg(-1)]. RESULTS: Anergic cells strongly suppressed the proliferation of naicaron;ve BALB/c splenocytes against the original (C3H) stimulator in a dose-dependent manner, but they failed to suppress the proliferation of naicaron;ve BALB/c splenocytes against the third-party (C57BL/6J) stimulator. The anergic state was reversed by both original (C3H) stimulator and additional exogenous IL-2. In in vivo studies, untreated irradiated BALB/c mice rejected C3H cardiac allografts with a mean survival time of (8.6 +/- 1.1) days, whereas those injected with the anergic cells rejected the allografts with a mean survival time of (11.8 +/- 1.9) days, which was slightly longer than that of the untreated mice. The protocol based on anergic cells injection plus rapamycin therapy could prolong allograft survival significantly [(29.6 +/- 4.4) days]. CONCLUSIONS: Anergic cells induced by the blockade of CD40-CD154 and CD28-B7 costimulatory pathways can act as potent immunoregulatory cells in vitro, and prolong cardiac allograft survival after adoptive transfer in the presence of rapamycin therapy. This procedure might be clinically useful for prolonging allograft survival if optimal protocols are developed.

Animals↗

PubMed2004

[A review of correlation, regression and multiple factors analysis methods.].

In clinical research, the relationships between two factors or among multiple factors are frequently explored. Dependence and covariation are two kinds of relationships between two factors. Regression and correlation analysis are the appropriate methods in measuring and evaluating those factors. Multiple analysis methods are widely used in the studies of risk factors among diseases, data analyses of diagnostic tests, effects evaluation of a prevention and treatment, analyses of prognosis, etc. Multiple analysis methods could interpret the influences of each factor more specifically than single factor analysis, and provide more possibilities to improve the quality of a research. In this review, the fundamental principle and utilities on clinical research of several statistical methods are introduced in this paper, such as linear correlation, linear regression, rank regression, rank correlation, multiple linear regression and logistic regression. It intends to help the clinicians and researchers to select the appropriate statistical methods to collect and analyze the data.

Epidemiologic Studies↗

PubMed2004

[A review of nonparametric test].

For some data which have skewness distribution or unknown distribution, it is impossible to apply parametric test. Nonparametric test will be a good choice for this kind of data in testing the distribution of the population. The nonparametric test is widely used in clinical research by its goodness of stability and adaptiveness. However, the effectiveness is cutting down by losing some essential information. So, parametric test will be recommended when the data meet the requirements. This paper introduces the basic concepts and methods of nonparametric test for the physicians to understand this important tool.

Humans↗

PubMed2003

Purification and characterization of thiols in an arsenic hyperaccumulator under arsenic exposure.

Pteris vittata (Chinese brake fern) is the first reported arsenic hyperaccumulator. To investigate the arsenic tolerance mechanism in this plant, reversed-phase HPLC with postcolumn derivatization was used to analyze the thiols induced under arsenic exposure. A major thiol in the plant leaflets was found to be responsive to arsenic exposure. The arsenic-induced compound was purified on a large scale by combining covalent chromatography and preparative reversed-phase HPLC. About 2 mg of this compound was isolated from 1 kg of fresh leaflets. The purified arsenic-induced compound was characterized using electrospray ionization mass spectrometry. A molecular ion (M + 1) of 540 and fragments were obtained, which indicated that the arsenic-induced thiol was a phytochelatin with two subunits (PC(2)). Compared to the classical methods for purification of phytochelatins, this new method is more specific, simple, and rapid and is suitable for purification of PCs in a large scale as well as sample preparation for mass spectrometry analysis.

Journal Article↗

PubMed2003

[Treatment of head and neck squamous cell carcinoma by recombinant adenovirus-p53 combined with radiotherapy: a phase II clinical trial of 42 cases].

OBJECTIVE: To evaluate the efficacy and safety of recombinant adenovirus-p53 (Adp53, SBN-1) combined with radiotherapy in treatment of head and neck squamous cell carcinoma (HNSCC). METHODS: Forty-two patients with HNSCC were randomly divided into 2 groups: gene therapy + radiotherapy group (GTRT group. n = 20, SBN-1 solution 1 x 10(12) VP was injected intratumorally once a week for 8 weeks and radiotherapy was begun since the 3rd day of gene therapy 5 fractions a week with the with the fraction dosage of 2 Gy and total dosage of 70 GY) and radiotherapy group (RT group. n = 22, the above regimen of radiotherapy was conducted). CT was conducted 5 weeks and 8 weeks after the beginning of treatment and 2 months after the finish of treatment (validation point) to calculate the size of tumor. Patients were monitored for adverse event and serum level of anti-adenoviral antibody. A comparative study was also performed on the immediate response rate by CT at the times when the dosages of 40 Gy and 70 Gy had been given. RESULTS: The average tumor reduction rates were (63 +/- 17)%, (82 +/- 18)%, and (90 +/- 16)% at the 40 Gy time point, 70 Gy time point, and validation point respectively in the GTRT group, all higher than those in the RT group (37 +/- 26)%, (62 +/- 39)%, and (70 +/- 34)% respectively, all P < 0.05. Random control study showed that the radio-sensitized enhancement rate was 1.72 at 40 Gy time point and the CR rate of the GRTR group at the validation point was 1.68 times higher than that of the RT group. Self-controlled study showed that the SBN-1 radio-sensitized enhancement ratio in the 4 GTRT group was 1.69 at 40 Gy time point and the CR rate of the GTRT group at validation point was 253% that of the RT group (P < 0.01). No dose-limiting toxicity and adverse events were noted, except transient fever after SBN-1 administration. CONCLUSION: A potentially effective gene therapeutic agent for HNSCC treatment, intratumoral injection of SBN-1 is safe.

Adenoviridae↗

PubMed2003

Identification of new subunits of the multiprotein mammalian TRRAP/TIP60-containing histone acetyltransferase complex.

The mammalian ATM/PI 3-kinase-related TRRAP protein was previously found to be a component of a multi-protein histone acetyltransferase (HAT) complex containing the HAT TIP60. In this report, we identify a previously uncharacterized protein encoded by the FLJ10914 ORF, which we designate MRGBP, as a new component of the TRRAP/TIP60 HAT complex. In addition, through purification of MRGBP and its associated proteins from HeLa cell nuclear extracts, we identify the thyroid receptor coactivating protein (TRCp120), DMAP1, and the related MRG15 and MRGX proteins as MRGBP-associating proteins, and we present biochemical evidence that they are previously unrecognized components of the TRRAP/TIP60 HAT complex. Taken together, our findings shed new light on the structure and function of the mammalian TRRAP/TIP60 histone acetyltransferase complex.

Acetyltransferases↗