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Biomedical subjects

Q Zheng

Publications and source records attributed to Q Zheng.

At least 19 recordsLinked to original sources
PubMed2011

Overexpression of ribosomal RNA in prostate cancer is common but not linked to rDNA promoter hypomethylation.

Alterations in nucleoli, including increased numbers, increased size, altered architecture and increased function are hallmarks of prostate cancer cells. The mechanisms that result in increased nucleolar size, number and function in prostate cancer have not been fully elucidated. The nucleolus is formed around repeats of a transcriptional unit encoding a 45S ribosomal RNA (rRNA) precursor that is then processed to yield the mature 18S, 5.8S and 28S RNA species. Although it has been generally accepted that tumor cells overexpress rRNA species, this has not been examined in clinical prostate cancer. We find that indeed levels of the 45S rRNA, 28S, 18S and 5.8S are overexpressed in the majority of human primary prostate cancer specimens as compared with matched benign tissues. One mechanism that can alter nucleolar function and structure in cancer cells is hypomethylation of CpG dinucleotides of the upstream rDNA promoter region. However, this mechanism has not been examined in prostate cancer. To determine whether rRNA overexpression could be explained by hypomethylation of these CpG sites, we also evaluated the DNA methylation status of the rDNA promoter in prostate cancer cell lines and the clinical specimens. Bisulfite sequencing of genomic DNA revealed two roughly equal populations of loci in cell lines consisting of those that contained densely methylated deoxycytidine residues within CpGs and those that were largely unmethylated. All clinical specimens also contained two populations with no marked changes in methylation of this region in cancer as compared with normal. We recently reported that MYC can regulate rRNA levels in human prostate cancer; here we show that MYC mRNA levels are correlated with 45S, 18S and 5.8S rRNA levels. Further, as a surrogate for nucleolar size and number, we examined the expression of fibrillarin, which did not correlate with rRNA levels. We conclude that rRNA levels are increased in human prostate cancer, but that hypomethylation of the rDNA promoter does not explain this increase, nor does hypomethylation explain alterations in nucleolar number and structure in prostate cancer cells. Rather, rRNA levels and nucleolar size and number relate more closely to MYC overexpression.

Adult↗
PubMed2001

Cell proliferation in cancer prevention; effects of preventive agents on estrogen-related endometrial carcinogenesis model and on an in vitro model in human colorectal cells.

Proto-oncogenes such as c-fos, c-jun and c-myc are known to relate to cell proliferation and differentiation. Some oriental herbal medicines like Glycyrrhizae radix or Juzen-taiho-to were found to suppress estradiol-17 beta (E2)-induced expression of c-fos/jun in uterine corpus and inhibited N-methyl-N-nitrosourea and E2-induced endometrial carcinogenesis in mice. It is suggested that the effects of such oriental drugs are exerted probably through suppression of estrogen-induced c-fos/jun expression and they are promising preventing agents for endometrial cancers. In the combined in vitro assay for cell proliferation (MTS assay) and apoptosis (DNA fragmentation) in human colorectal cancer cells (Colo 320), a number of naturally occurring chemopreventive agents such as curcumin, quercetin, auraptene, 1'-acetoxychavicol acetate (ACA) and indole-3-carbinol were shown to generate apoptosis as well as to inhibit cell proliferation. The results suggest a mode of action of these chemopreventive agents and also imply that such in vitro short term assay is useful for detection of new agents for cancer prevention.

Adenocarcinoma↗
PubMed2001

A double-labeled preparation for simultaneous measurement of [3H]-noradrenaline and [14C]-glutamic acid exocytosis from streptolysin-O (SLO)-perforated synaptosomes.

We have developed a novel method to examine [3H]-noradrenaline and [14C]-glutamate release from the same sample of streptolysin-O (SLO) perforated rat cortical synaptosomes. Ca2+ -dependent [3H]-noradrenaline and [14C]-glutamate release was examined at different temperatures and was found to be greater at 30 degrees C than at 25 degrees C. Ca2+ -dependent release of [3H]-noradrenaline is more ATP dependent than Ca2+ -dependent release of [14C]-glutamate. No significant reuptake of either neurotransmitter by the perforated synaptosomes was detected, indicating all the synaptosomes were indeed perforated. Incubations with 1 mM ouabain, a specific Na+,K+ -ATPase inhibitor, slightly increased Ca2+ -dependent release of both neurotransmitters. [3H]-noradrenaline is released from large dense-core vesicles and [14C]-glutamate is released from small clear synaptic vesicles, so one can directly compare and contrast neurotransmitter release mechanisms between large dense-core vesicles and small clear synaptic vesicles using this preparation.

Adenosine Triphosphate↗
PubMed2001

Effect of a rippling mode on resonances of carbon nanotubes.

A recent study determined the Young's modulus of carbon nanotubes by measuring resonance frequency and using the modulus-frequency relation resulting from the linear vibration theory. It leads to the report that the Young's modulus decreases sharply, from about 1 to 0.1 TPa with the diameter D increasing from 8 to 40 nanometers, and the investigators attributed this decrease to the emergence of an unusual bending mode during the measurement that corresponds to rippling on the inner arc of the bent nanotubes. The nonlinear analysis presented in this paper that captures the rippling mode suggests that the effective Young's modulus can indeed decrease substantially with increasing diameter, and that the results from the classical linear theory may be invalid in such measurements.

Journal Article↗
PubMed2001

Biomarker risk assessment and bladder cancer detection in a cohort exposed to benzidine.

BACKGROUND: Cancer screening with highly sensitive, specific biomarkers that reflect molecular phenotypic alterations is an attractive strategy for cancer control. We examined whether biomarker profiles could be used for risk assessment and cancer detection in a cohort of Chinese workers occupationally exposed to benzidine and at risk for bladder cancer. METHODS: The cohort consisted of 1788 exposed and 373 nonexposed workers, followed from 1991 through 1997. We assayed urothelial cells from voided urine samples for DNA ploidy (expressed as the 5C-exceeding rate [DNA 5CER]), the bladder tumor-associated antigen p300, and a cytoskeletal protein (G-actin). Workers were stratified into different risk groups (high, moderate, and low risk) at each examination based on a predefined biomarker profile. For workers who developed bladder cancer, tumor risk assessment was analyzed from samples collected 6-12 months before the cancer diagnosis. The associations between risk group and subsequent development of bladder cancer were analyzed by Cox proportional hazards regression analysis and logistic analysis, after adjustment. All statistical tests were two-sided. RESULTS: Twenty-eight bladder cancers were diagnosed in exposed workers and two in nonexposed workers. For risk assessment, DNA 5CER had 87.5% sensitivity, 86.5% specificity, an odds ratio (OR) of 46.2 (95% confidence interval [CI] = 8.1 to 867.0), and a risk ratio (RR) of 16.2 (95% CI = 7.1 to 37.0); p300 had 50.0% sensitivity, 97.9% specificity, an OR of 40.0 (95% CI = 9.0 to 177.8), and an RR of 37.9 (95% CI = 16.8 to 85.3). The risk of developing bladder cancer was 19.6 (95% CI = 8.0 to 47.9) times higher in workers positive for either the DNA 5CER or p300 biomarkers than in workers negative for both biomarkers and 81.4 (95% CI = 33.3 to 199.3) times higher in workers positive for both biomarkers. G-actin was a poor marker of individual risk. CONCLUSIONS: Occupationally exposed workers at risk for bladder cancer can be individually stratified, screened, monitored, and diagnosed based on predefined molecular biomarker profiles.

Actins↗
PubMed2001

Osteogenic potential of cultured bone marrow stromal cells transfected with transforming growth factor beta 1 gene in vitro.

To study the osteogenic potential of cultured bone marrow stromal cells (BMSCs) transfected with transforming growth factor beta 1 (TGF-beta 1) gene in vitro, cultured BMSCs were transfected with the complexes of pcDNA3-TGF-beta 1 and Lipofectamine Reagent in vitro. The cell proliferation was detected by MTT method and the morphological features of transfected BMSCs was observed. ALP stains and PNP method were used to measure ALP activity. In addition, the collagen type I propeptides and mineralized matrixes were examined by immunohistochemical staining and tetracycline fluorescence labeling respectively. The morphological and biological characters of the transfected BMSCs were similar to those of osteoblasts and the cell proliferation was promoted. The cell layer displayed strong positive reaction for ALP stains and immunohistochemical staining. ALP activity and collagen type I expression increased remarkably after transfection. Mineralized matrixes formed earlier and more in transfected BMSCs as compared with control group. It is concluded that transfecting with TGF-beta 1 gene could promote the osteogenic potential of cultured BMSCs.

Alkaline Phosphatase↗
PubMed2001

On the dispersion index of a Markovian molecular clock.

The number of nucleotide substitutions accumulated in a gene or in a lineage is an important random variable in the study of molecular evolution. Of particular interest is the ratio of the variance to the mean of that random variable, often known as the dispersion index. Because nucleotide substitution is most commonly modeled by a continuous-time four-state Markov chain, this paper provides a systematic method of computing the dispersion indices exhibited by a continuous-time four-state Markov chain. Using this method along with computer algebra and Monte Carlo simulation, this paper offers partially proven conjectures that were supported by thorough computer experiments. It is believed that the Tamura model, the equal-input model and the Takahata-Kimura model always exhibit dispersion indices less than 2. It is also believed that a general four-state model can be chosen to exhibit a dispersion index of any desired magnitude, although the chance of a randomly chosen such model exhibiting a dispersion index greater than 2 is as small as about 2%. Relevance of these findings to the neutral theory is discussed.

Computer Simulation↗
PubMed2001

Age-related effects of chlorpyrifos on acetylcholine release in rat brain.

Chlorpyrifos (CPF) is an organophosphorus insecticide that elicits toxicity through inhibition of acetylcholinesterase (AChE). Young animals are markedly more sensitive than adults to the acute toxicity of CPF. We evaluated acetylcholine (ACh) release and its muscarinic receptor-mediated regulation (i.e. muscarinic autoreceptor function, MAF) during maturation as a possible contributing factor to age-related differences in sensitivity. Cortical and striatal slices were prelabeled with [3H]choline chloride, superfused in the presence or absence of the anticholinesterase physostigmine (PHY, 20 microM) and stimulated twice (S1 and S2) with a high concentration of potassium chloride (20 mM). Depolarization-stimulated ACh release (DSAR) was lowest in neonatal, intermediate in juvenile and markedly higher in adult tissues. MAF was not detectable in tissues from neonatal rats but was present in juvenile and adult tissues. ACh release and MAF were studied at 4, 24 and 96 h following oral exposure to CPF (0, 0.5 or 1 x LD10). In general, 40-60% and 80-90% maximal AChE inhibition followed exposure to the respective 0.5 and 1 x LD10 dosages. DSAR was decreased in neonatal cortex 1 day after LD10 exposure but increased in juvenile striatum 1 day after LD10 treatment. In adults, DSAR was reduced at 4 and 24 h after exposure, but increased 96 h after CPF exposure. In juveniles, MAF was reduced in both brain regions at 24 h after 0.5LD10 exposure and at 24 and 96 h after LD10 exposure in cortex. A later reduction in MAF was noted in adult tissues (i.e. only at 96 h after LD10 treatment). Together, the results suggest that ACh release dynamics in brain vary markedly during postnatal maturation and that acute CPF exposure can alter ACh release in an age-related manner. The functional status of presynaptic processes regulating neurotransmitter release may contribute to age-related neurotoxicity elicited by high-dose exposures to chlorpyrifos.

Acetylcholine↗
PubMed2001

A mechanistic approach to modelling the risk of liver tumours in mice exposed to fumonisin B1 in the diet.

Data from the National Toxicology Program's carcinogenesis study of fumonisin B1 in B6C3F1 mice, conducted at the National Center for Toxicological Research, were used to fit the Moolgavkar-Venzon-Knudson (MVK) two-stage, clonal-expansion model of carcinogenesis. In addition to tumour data from the conventional 2-year bioassay, the study included data on tissue weights, cell proliferation, cell death, and sphingolipid metabolism in primary target organs. The model was used to predict 2-year liver tumour rates in female and male mice based on differences among dose groups in the effect of fumonisin B1 on the growth of normal tissue and on the proliferation of preneoplastic cells as a compensatory response to sphinganine-induced cell death. Fumonisin B1 was assumed to be non-genotoxic, i.e. the model did not include any effect of fumonisin B1 on either of the two mutation rates of the MVK model. The model was able to reproduce reasonably well the observed tumour rates in both female and male mice, predicting substantially increased rates above background only at the highest doses of fumonisin B1 in females.

Animals↗
PubMed2001

Fargosides A-E, triterpenoid saponins from Holboellia fargesii.

Five new triterpenoid saponins, fargosides A, B, C, D, and E, were isolated from the roots of Holboellia fargesii. The structures of fargosides A-E were elucidated on the basis of chemical and physicochemical evidence and found to be 3beta,20alpha-dihydroxy-29-norolean-12-en-28-oic acid 3-O-beta-D-xylopyranosyl-(1-->2)-beta-D-glucopyranoside (1), 3beta,20alpha,24-trihydroxy-29-norolean-12-en-28-oic acid 23-O-beta-D-fucopyranosyl-(1-->2)-[alpha-L-arabinopyranosyl-(1-->3)]-beta-D-glucopyranoside (2), 3beta,23-dihydroxy-30-norolean-2,20(29)-dien-28-oic acid 3-O-alpha-L-arabinopyranosyl-(1-->2)-[beta-D-glucopyranosyluronic acid-(1-->3)]-alpha-L-arabinopyranoside (3), 3beta,23-dihydroxy-30-norolean-12,20(29)-dien-28-oic acid 3-O-methyl beta-D-glucopyranosyluronate-(1-->3)-alpha-L-arabinopyranoside (4), and 3beta,23-dihydroxy-olean-12-en-28-oic acid 3-O-methyl beta-D-glucopyranosyluronate-(1-->3)-alpha-L-arabinopyranoside (5), respectively.

Drugs, Chinese Herbal↗
PubMed2001

Robust structure from motion estimation using inertial data.

The utility of using inertial data for the structure-from-motion (SfM) problem is addressed. We show how inertial data can be used for improved noise resistance, reduction of inherent ambiguities, and handling of mixed-domain sequences. We also show that the number of feature points needed for accurate and robust SfM estimation can be significantly reduced when inertial data are employed. Cramér-Rao lower bounds are computed to quantify the improvements in estimating motion parameters. A robust extended-Kalman-filter-based SfM algorithm using inertial data is then developed to fully exploit the inertial information. This algorithm has been tested by using synthetic and real image sequences, and the results show the efficacy of using inertial data for the SfM problem.

Journal Article↗
PubMed2001

[Immunohistochemical and clinical studies on sub-corneal flap epithelial implantation accompanied by flap melting after excimer laser in situ keratomileusis].

OBJECTIVE: To study the immunohistochemical and clinical characteristics of the corneal epithelial cells implanted under the flap accompanied by the flap melting after excimer laser in situ keratomileusis (LASIK) and the method of management. METHODS: In eight eyes (In 4 eyes a part of the flap melted.) with corneal epithelial cells implanted under the flap after LASIK, the corneal flap was torn again. The implanted tissue was removed. After washing between the interfaces, the flap was repositioned. The implanted tissue was immunohistochemically stained by using four kinds of monoclonal antibodies and using terminal deoxyribonucleotide transferase-mediated dUTP nick end labeling (TUNEL) method. RESULTS: Early in the course, the disorder appeared on the temporal side, expanded and thickened. The defective periphery of the corneal flap presented as a partial lunar eclipse. The melting process was self-limited in 3 months. The result was good after the implanted tissue was removed. The implanted material was stained by using HE, immunohistochemical and TUNEL methods. Some vesicle-like degeneration in the implanted layer was found. There was lysozyme in the vesicles, and the cells of implanted layer possessed a trend of apoptosis. All the cells were dead in the vesicles. CONCLUSIONS: The progress of corneal epithelial implantation under corneal flap after LASIK may include 3 periods: epithelial implantation, corneal flap melting and self-limitation. Early in the course, the implanted material presented as a thin film. Afterwards, it becomes a non-structural material. Possibly the melting of the corneal flap is caused by apoptosis. Therefore, the implanted epithelium should be removed early.

Adult↗
PubMed2001

[The management of bony burn with skin flap transplant with preservation of sequestrum].

OBJECTIVE: To study the management of bony burn, so as to improve the quality of bony burn treatment, to decrease the complications and to shorten the course. METHODS: Retrospective review of 36 cases with bony burn cured since 1992 was done in terms of treatment strategy before skin flap transplant to cover the burn wound, i e sequestrum preserved or partial removal. RESULTS: There exhibited no complications, such as infection, osteomyelitis and pathologic bone fracture in all these cases. CONCLUSION: The treatment strategy described here could be advocated in view of its reliable coverage of the wound, shortening of the bony burn course and reduction of complication.

Adolescent↗
PubMed2000

Altered patterns of gene expression in response to myocardial infarction.

The use of cDNA microarrays has made it possible to simultaneously analyze gene expression for thousands of genes. Microarray technology was used to evaluate the expression of >4000 genes in a rat model of myocardial infarction. More than 200 genes were identified that showed differential expression in response to myocardial infarction. Gene expression changes were monitored from 2 to 16 weeks after infarction in 2 regions of the heart, the left ventricle free wall and interventricular septum. A novel clustering program was used to identify patterns of expression within this large set of data. Unique patterns were revealed within the transcriptional responses that illuminate changes in biological processes associated with myocardial infarction.

Animals↗
PubMed2000

[Investigation of the effects of biotic field of plant seedling on human body].

In this paper we investigated the effects on human bodies after being placed in the Jiang's guideti cabin with biotic field to receive the plant seedlings' irradiating biological electromagnetic waves. The results found that the erythrocyte membrane permeability and fragidity were decreased, its tenacity increased, the secretion of thyroid and sexual hormones increased, the immune function enhanced and there was no significant alteration of the adrenal cortical hormone secretion. It is suggested that the electromagnetic wave from the plant seedlings is beneficial to the erythrocyte function, improves the metabolism, enhances the adolescent activities, improves sexual activity and enhances immune function, thus it is effective to health care and rejuvenation.

Adult↗
PubMed2000

Clonality analysis of defined cell populations in paraffin-embedded tissue sections by RT-PCR amplification of X-linked G6PD gene.

This paper establishes a method of clonality analysis using the reverse transcription-polymerase chain reaction (RT-PCR) to amplify X-linked G6PD transcripts on defined cell populations microdissected from archival, paraffin-embedded tissue sections. Four known monoclonal low-grade B-cell lymphomas from females who were heterozygous (informative) at the 1131 exonic polymorphic locus of the G6PD gene were used to validate the method. Lymphoma and reactive lesions in each case were separated by microdissection. In order to preserve the intact RNA species in the lesion, sections were digested on the slides before microdissection. A one-step RT-PCR was performed with a single pair of primers, one of which contained a mismatched base adjacent to the polymorphic site, to generate a PvuI cutting site. Successful amplification and allele identification by PvuI digestion were achieved from all RNA samples studied. Three of four samples from non-neoplastic reactive lesions showed two bands with equal intensity, representing transcription of the two alleles of the G6PD gene, while the corresponding tumour samples demonstrated a biased intensity in one allele, indicating monoclonality. To assess the method further, the clonal nature of in situ and invasive breast cancers was examined, along with adjacent normal breast tissue and hyperplastic lesions from three informative females from our archives. Apart from the clusters of normal terminal duct-lobular units, all lesions were monoclonal. This result is in agreement with data derived from other X-linked gene studies and loss of heterozygosity (LOH) analyses of pre-invasive breast disease. The results suggest that the clonality analysis method presented here is simple and reliable, and is therefore potentially applicable in a wide range of pathological conditions.

Breast↗
PubMed2000

Isolated pelvic hyperthermochemotherapeutic perfusion--an experimental study on isolating efficacy.

Hyperthermochemotherapeutic perfusion model through isolated pelvic vessels was developed to evaluate the leakage of hyperthermia and drugs (such as adriamycin) from the isolated pelvic circulation to systemic circulation and its associated side/toxic effects. The isolated pelvic circulation was perfused through a femoral artery catheter with hyperthermic (48 degrees C to 55 degrees C) adriamycin solution (50 micrograms/ml) for 30 min. The efflux was drained through a femoral vein catheter. And the pelvic temperature was kept at the level of 43 +/- 0.5 degrees C. The temperature of pelvic circulation was kept at 4 degrees C to 5 degrees C greater than the systemic/core temperature. The adriamycin concentration of pelvic efflux was 12 to 46 folds of that of systemic serum. The difference between them was very significant (P < 0.001). As the perfusion pressure was increased, which kept lower than the mean systemic artery pressure, the leakage of the adriamycin from the isolated pelvic circulation to systemic circulation was increased, but there was no significant difference between them (P > 0.05). During isolated perfusion, the systemic blood dynamics remained stable and there were no organic injuries on the important organs. It was suggested that the isolating efficacy of the modality of isolated pelvic hyperthermochemotherapeutic perfusion through vessels was rather high. The hyperthermia and drugs could be effectively limited in the isolated pelvic region with minor side effects on the systemic circulation and important organs.

Animals↗