Biomedical subjects

Yong Cai

Publications and source records attributed to Yong Cai.

44 records · Page 3Linked to original sources

PubMed2003

Identification of mammalian Mediator subunits with similarities to yeast Mediator subunits Srb5, Srb6, Med11, and Rox3.

The Mediator is a multiprotein coactivator required for activation of RNA polymerase II transcription by DNA binding transactivators. We recently identified a mammalian homologue of yeast Mediator subunit Med8 and partially purified a Med8-containing Mediator complex from rat liver nuclei (Brower, C. S., Sato, S., Tomomori-Sato, C., Kamura, T., Pause, A., Stearman, R., Klausner, R. D., Malik, S., Lane, W. S., Sorokina, I., Roeder, R. G., Conaway, J. W., and Conaway, R. C. (2002) Proc. Natl. Acad. Sci. U. S. A. 99, 10353-10358). Analysis of proteins present in the most highly purified Med8-containing fractions by tandem mass spectrometry led to the identification of many known mammalian Mediator subunits, as well as four potential Mediator subunits exhibiting sequence similarity to yeast Mediator subunits Srb5, Srb6, Med11, and Rox3. Here we present direct biochemical evidence that these four proteins are bona fide mammalian Mediator subunits. In addition, we identify direct pairwise binding partners of these proteins among the known mammalian Mediator subunits. Taken together, our findings identify a collection of novel mammalian Mediator subunits and shed new light on the underlying architecture of the mammalian Mediator complex.

Animals↗

PubMed2003

Organic compounds and trace metals of anthropogenic origin in sediments from Montego Bay, Jamaica: assessment of sources and distribution pathways.

Surface sediments throughout Montego Bay, Jamaica were collected in 1995 and analyzed for their trace metal and trace organic contaminant content. A variety of trace metals, petroleum hydrocarbons, polycyclic aromatic hydrocarbons, coprostanol as well as chlorinated hydrocarbons such as pesticides and polychlorinated biphenyls were detected and provide evidence for several anthropogenic inputs to the bay. Two main sources of these chemicals are the Montego River and the North Gully, the latter being more significant. Particle-associated pollutants were found to be distributed along the Montego River plume, as well as being transported by the prevailing water currents to the South-Western sections of the bay, probably through re-suspension of enriched fine sediments from the North Gully outfall area.

Environmental Monitoring↗

PubMed2003

Arsenic species and leachability in the fronds of the hyperaccumulator Chinese brake (Pteris vittata L.).

Arsenic speciation is important not only for understanding the mechanisms of arsenic accumulation and detoxification by hyperaccumulators, but also for designing disposal options of arsenic-rich biomass. The primary objective of this research was to understand the speciation and leachability of arsenic in the fronds of Chinese brake (Pteris vittata L.), an arsenic hyperaccumulator, with an emphasis on the implications for arsenic-rich biomass disposal. Chinese brake was grown for 18 weeks in a soil spiked with 50 mg As kg(-1) as arsenate (AsO4(3-)), arsenite (AsO3(3-)), dimethylarsinic acid (DMA), or methylarsonic acid (MMA). Plant samples were extracted with methanol/water (1:1) and arsenic speciation was performed using high performance liquid chromatography coupled with atomic fluorescence spectrometry. The impacts of air-drying on arsenic species and leachability in the fronds were examined in the laboratory. After 18 weeks, water-soluble arsenic in soil was mainly present as arsenate with little detectable organic species or arsenite regardless of arsenic species added to the soil. However, arsenic in the fronds was primarily present as inorganic arsenite with an average of 94%. Arsenite re-oxidation occurred in the old fronds and the excised dried tissues. Arsenic species in the fronds were slightly influenced by arsenic forms added to the soil. Air-drying of the fronds resulted in leaching of substantial amounts of arsenic. These findings can be of significance when looking at disposal options of arsenic-rich biomass from the point of view of secondary contamination.

Arsenates↗

PubMed2002

Arsenic speciation and distribution in an arsenic hyperaccumulating plant.

Arsenic-contaminated soil is one of the major arsenic sources for drinking water. Phytoremediation, an emerging, plant-based technology for the removal of toxic contaminants from soil and water, has been receiving renewed attention. Although a number of plants have been identified as hyperaccumulators for the phytoextraction of a variety of metals, and some have been used in field applications, no hyperaccumulator for arsenic had been previously reported until the recent discovery of Brake fern (Pteris vittata), which can hyperaccumulate arsenic from soils. This finding may open a door for phytoremediation of arsenic-contaminated soils. Speciation and distribution of arsenic in the plant can provide important information helpful to understanding the mechanisms for arsenic accumulation, translocation, and transformation. In this study, plant samples after 20 weeks of growth in an arsenic-contaminated soil were used for arsenic speciation and distribution study. A mixture of methanol/water (1:1) was used to extract arsenic compounds from the plant tissue. Recoveries of 85 to 100% were obtained for most parts of the plant (rhizomes, fiddle heads, young fronds and old fronds) except for roots, for which extraction efficiency was approximately 60%. The results of this study demonstrate the ability of Brake fern as an arsenic hyperaccumulator. It transfers arsenic rapidly from soil to aboveground biomass with only minimal arsenic concentration in the roots. The arsenic is found to be predominantly as inorganic species; and it was hypothesized that the plant uptakes arsenic as arsenate [As(V)I and arsenate was converted to arsenite [As(III)] within the plant. The mechanisms of arsenic uptake, translocation, and transformation by this plant are not known and are the objectives of our on-going research.

Arsenic↗

PubMed2002

Assessment of arsenic mobility in the soils of some golf courses in South Florida.

High concentrations of arsenic have been detected in soils and underlying groundwater of some South Florida golf courses, indicating the possible impact of the application of arsenic-containing herbicides. The mobility of arsenic in the soils from selected golf courses was studied using a simple two-step sequential extraction procedure. Sodium nitrate (0.1 M), potassium dihydrogen phosphate (0.1 M) and concentrated nitric acid were used to obtain mobile, mobilizable, and pseudo total arsenic fractions. Soils were separated into fine (<0.25 mm) and large (0.25-0.75 mm) particle size fractions. Arsenic contents were correlated with the distribution of iron (R2=0.4827), manganese (R2=0.7674) and aluminum (R2=5459) in the particle size fractions, while such correlation was not observed for soil organic matter, indicating that the oxides/hydroxides of iron, manganese and aluminum control the distribution of arsenic in these soils. Sodium nitrate and potassium dihydrogen phosphate extractants used in this study extracted large portions of arsenic from most soil samples studied. This is especially true for the fine fraction where the extractable arsenic ranged from 9.2 to 51.3% with an average of 28.7 +/- 13.3%, whereas in the large fraction, arsenic ranged from 7.2 to 24.7% with an average of 15.4 +/- 6.4%. These extractants, however, release only small amounts of iron, manganese, and aluminum. It seems likely that arsenic can be released by sodium nitrate and potassium dihydrogen phosphate without significant dissolution of the oxides/hydroxides of iron, manganese, and aluminum in these soil samples.

Aluminum↗

PubMed2002

[Chronobiologic contrast of expression of p53, p16, and cyclin D1 in hepatocarcinoma cells].

OBJECTIVE: To contrast the feature of different periods of p53, p16, and cyclin D1 expression in cells of hepatocarcinoma. METHODS: Sixty hepatocarcinoma specimens were collected and divided into three periods in one yearly cycle with each period of 20 cases. Hepatocellular carcinoma was documented in all cases by pathomorphological classification. Edmondson-Steinet grading belonged to II~III stages. The expression of gene proteins of p53, p16, and cyclin D1 was determined by immunohistochemical assay (S-P method). The expressive intensity was analysed by the rank test. RESULTS: p16 expression showed significant difference of period (H=10.334, P<0. 05). Arpil-July was the high expressive period. CONCLUSIONS: p16 may take an important role in the chronobiologic mechanism of gene control of hepatocyte canceration and hepatocarcinoma cell growth.

Carcinoma, Hepatocellular↗

PubMed2002

[Expression of NF-kappa B in human bladder cancer and its clinical significance].

BACKGROUND & OBJECTIVE: Studies on solid cancer(such as breast cancer, hepatocellular cancer, pancreatic cancer) indicated that the abnormal expression of nuclear transcription factor Kappa B (NF-kappa B) regulates angiogenesis and cyclin-related genes. This study was designed to investigate the expression differences of NF-kappa B and its regulated genes between human primary transitional cell carcinoma(TCCs) of bladder and non-cancer bladder mucosa and its clinical significance. METHODS: Forty-three frozen sections including 30 bladder cancer and 13 non-cancer bladder mucosa were subjected to immunohistochemistry and nucleus staining for determining levels of NF-kappa B family and I kappa B alpha; Five paired cancer and non-cancer specimens were subjected to Western blot for analysis p65, an important subtype of NF-kappa B; Thirteen paired specimens were subjected to RT-PCR for determination mRNA levels of p50, p52, p65, c-Rel, RelB, I kappa B alpha, CyclinD1, IL-8. RESULTS: Expressions of p50, p52, p65, c-Rel, RelB, I kappa B alpha, CyclinD1, IL-8 mRNAs in bladder cancer were higher than that in non-cancer bladder mucosa (P < 0.01, P < 0.05, P < 0.01, P < 0.01, P < 0.05, P < 0.05, P < 0.05 and P < 0.05, respectively). Nucelus stainings of p50, p52, p65, c-Rel, RelB were also stronger in bladder cancer(P < 0.01, P < 0.01, P < 0.01, P < 0.01 and P < 0.01, respectively). Moreover, p65 was expressed more in cancer tissue than that in non-cancer mucosa evidenced by Western blot. In bladder cancer, the ranking score differences of p52, p65, c-Rel protein between lymphatic metastasis group and non-lymphatic metastasis group were statistically significant (P < 0.01, P < 0.01, P < 0.05, respectively). CONCLUSIONS: Compared to noncancer bladder mucosa, expressions of NF-kappa B family and its regulated genes in bladder cancer are markedly higher. NF-kappa B may be related to lymphatic metastasis.

Adult↗

PubMedDate not supplied

Optical detection methods for mass spectrometry of macroions.

Detection of macroions has been a challenge in the field of mass spectrometry. Conventional ionization-based detectors, relying on production and multiplication of secondary electrons, are restricted to detection for charged particles of m/z < 1 x 10(6). While both energy-sensitive and charge-sensitive detectors have been developed recently to overcome the limitation, they are not yet in common use. Photon-sensitive detectors are suggested to be an alternative, with which detection of macroions (or charged particles) by either elastic light scattering (ELS) or laser-induced fluorescence (LIF) has been possible. In this article, we provide a critical review on the developments of novel optical detection methods for mass spectrometry of macroions, including both micron-sized and nano-sized synthetic polymers as well as high-mass biomolecules. Design and development of new spectrometers making possible observations of the mass spectra of macroions with sizes in the range of 10-10(3) nm or masses in the range of 1-10(6) MDa are illustrated. The potential and promise of this optical approach toward macroion detection with high efficiency are discussed in practical aspects.

Equipment Design↗