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Biomedical subjects

R Cheng

Publications and source records attributed to R Cheng.

At least 55 records · Page 3Linked to original sources
PubMed1998

[Genotype distribution of hepatitis C virus in hepatocellular carcinoma tissue in Hunan province].

Genotypes of hepatitis C virus(HCV) were detected by PCR using type-specific primer in 50 patients' hepatocellular carcinoma(HCC) tissue. The results showed that in the 50 HCC specimens, 30(60%) and 3(6%) were infected with the HCV type II and III, 5(10%) and 8(16%) with type II + III and type II + IV, 2(4%) with type II + I + III in combination, respectively. 2 cases were negative for HCV. These data suggest that HCV type II may be a predominant genotype related to hepatocarcinogenesis in Hunan Province, some cases of HCC may result from coinfection of HCV type II and other genotypes, and only few HCC be separately caused by infection of HCV type III.

Adult↗
PubMed1998

[The relationship between C-erbB-2 expression with cell proliferative activity and prognosis of nasopharyngeal carcinomas].

UNLABELLED: C-erbB-2 and proliferating cell nuclear antigen (PCNA) were detected by immunohistochemical and in situ hybridization methods in nasopharyngeal carcinomas(NPC) and pericarcinomatous tissues(PCT). Some NPC cases were followed up for more than 5 years. RESULTS: The positive rates of C-erbB-2 protein and C-erbB-2 mRNA expression were 87.8%, and 84.0%, respectively in NPC and 74.6% and 76.5%, respectively in PCT. There was a coexpression of C-erbB-2 protein and mRNA. The significant difference for PCNA staining intensity index(S II) existed in the vesico-nuclear and poorly differentiated types of NPC and in the C-erbB-2 staining cases of NPC. No correlation was found between the expression of C-erbB-2 protein and the clinical stage and metastasis as well as survival rate. CONCLUSION: The C-erbB-2 gene overexpression and cell abnormal proliferation are associated with the carcinogenesis and development of NPC. It is helpful to examine both C-erbB-2 gene expression and PCNA in NPC to evaluate the malignant degree and the effect of radiotherapy.

Carcinoma, Squamous Cell↗
PubMed1997

Myocyte apoptosis during acute myocardial infarction in the mouse localizes to hypoxic regions but occurs independently of p53.

Significant numbers of myocytes die by apoptosis during myocardial infarction. The molecular mechanism of this process, however, remains largely unexplored. To facilitate a molecular genetic analysis, we have developed a model of ischemia-induced cardiac myocyte apoptosis in the mouse. Surgical occlusion of the left coronary artery results in apoptosis, as indicated by the presence of nucleosome ladders and in situ DNA strand breaks. Apoptosis occurs mainly in cardiac myocytes, and is shown for the first time to be limited to hypoxic regions during acute infarction. Since hypoxia-induced apoptosis in other cell types is dependent on p53, and p53 is induced by hypoxia in cardiac myocytes, we investigated the necessity of p53 for myocyte apoptosis during myocardial infarction. Myocyte apoptosis occurs as readily, however, in the hearts of mice nullizygous for p53 as in wild-type littermates. These data demonstrate the existence of a p53-independent pathway that mediates myocyte apoptosis during myocardial infarction.

Animals↗
PubMed1997

Cloning and chromosomal mapping of four putative novel human G-protein-coupled receptor genes.

We report the discovery of four novel human putative G-protein-coupled receptor (GPCR) genes. Gene GPR20 was isolated by amplifying genomic DNA with oligos based on the opioid and somatostatin related receptor genes and subsequent screening of a genomic library. Also, using our customized search procedure of a database of expressed sequence tags (dbEST), cDNA sequences that partially encoded novel GPCRs were identified. These cDNA fragments were obtained and used to screen a genomic library to isolate the full-length coding region of the genes. This resulted in the isolation of genes GPR21, GPR22 and GPR23. The four encoded receptors share significant identity to each other and to other members of the receptor family. Northern blot analysis revealed expression of GPR20 and GPR22 in several human brain regions while GPR20 expression was detected also in liver. Fluorescence in situ hybridization (FISH) was used to map GPR20 to chromosome 8q, region 24.3-24.2, GPR21 to chromosome 9, region q33, GPR22 to chromosome 7, region q22-q31.1, and GPR23 to chromosome X, region q13-q21.1.

Amino Acid Sequence↗
PubMed1997

Cigarette smoking, sex hormones and bone density in women.

It is known that among women over the age of 65, bone mineral density is lower, and the risk of hip fracture higher, in smokers than non-smokers. We report a study in 1334 health pre- and post-menopausal women aged 35-64 years, to determine whether this effect can be attributed to lower oestrogen levels in smokers. Among 676 premenopausal women forearm bone density was no lower in smokers (95% confidence interval 1% lower, 4% higher). Among 543 postmenopausal women who had not used hormone replacement therapy (HRT) for more than a year there was no statistically significant difference, but the lower confidence interval was consistent with a lower bone density in older smokers (by 8% at age 55-59, 16% at age 60-64). Measurements in 194 postmenopausal women not taking HRT showed that oestrone and oestradiol were similar in smokers and non-smokers, as were cortisol and FSH, LH and prolactin. Meta-analysis of the present study and previous studies confirmed significantly higher levels in smokers of the androgens DHEAS (by 37%) and androstenedione (by 34%). Oestrogens were no lower in smokers, and the lower confidence limit excluded more than a trivial effect of smoking in lowering oestrogen. These results indicate that the recognised lower bone density in elderly smokers cannot be explained by an effect of smoking on oestrogen, since in premenopausal women bone density is no lower in smokers and in postmenopausal women oestrogens are no lower in smokers. The data suggest a balance between higher androgen levels but lower rates of conversion of androgens to oestrogens in smokers. The effect of smoking on bone may be due to impaired response of bone and other target organs to oestrogen, or to actions independent of oestrogen.

Adult↗
PubMed1997

Normal CD5+ B lymphocytes are poor stimulators in the autologous mixed lymphocyte reaction (AMLR).

The AMLR is decreased in chronic lymphocytic leukaemia (CLL), which is characterized by a monoclonal expansion of CD5+ B lymphocytes. Since B cells are used to stimulate the AMLR, we investigated the capacity of normal CD5+ B cells to function as stimulators in the AMLR. We isolated B cells from the peripheral blood of normal individuals and fractionated them into subpopulations enriched for CD5+ and CD5- cells, which were used as stimulators in the AMLR. We found that the CD5- B cells were excellent stimulators, whereas stimulation of AMLR by B cells enriched for CD5+ cells resulted in significantly reduced proliferative responses (P < 0.005). This suggests that the reduced AMLR in CLL is due to the predominance of CD5+ B lymphocytes in the stimulating cell population.

B-Lymphocytes↗
PubMed1997

Cloning, sequencing, and embryonic expression of an N-ras proto-oncogene isolated from an enriched zebrafish (Danio rerio) cDNA library.

An enriched zebrafish (Danio rerio) complementary DNA library was constructed for screening of ras-related genes, and a positive clone was isolated from one plate of 3 x 10(4) plaques. This clone, Zras-B1, carried an insert of 2592 base pairs (bp) with an open reading frame encoding a ras p21 protein of 188 amino acids. The deduced amino-terminal 86 amino acid residues and the carboxy-terminal CAAX binding motif are identical to mammalian ras. The full-length Zras-B1-encoded protein is most closely related to human N-ras (91% identity), with lesser homology to Ha-ras (84%) and Ki-ras (85%). Preliminary screening data also indicate other ras genes in zebrafish, at least one of which is also transcribed in adults. A Zras-B1-related 3.1-kb transcript was found to be abundant in embryos from zygote through gastrulation, and may be maternally derived.

Amino Acid Sequence↗
PubMed1997

Zebrafish (Danio rerio) p53 tumor suppressor gene: cDNA sequence and expression during embryogenesis.

Three methods were used in succession to screen a whole adult zebrafish cDNA library for expressed p53-like genes. The sequences of the resultant clones describe an open reading frame 1122 nucleotides in length, with another 43 and 940 bases of 5' and 3' untranslated sequence, respectively. The deduced amino acid sequence of the zebrafish p53 protein is 63% identical to that of trout and 48% identical to that of human p53. Two of the three zebrafish clones overlap to span the entire reported cDNA sequence and are identical in their deduced amino acid sequence over their coincident length. The third clone contains a conservative amino acid change, as well as an inserted amino acid subsequently found to be at the junction of exons 2 and 3, suggestive of alternative splicing in the p53 mRNA for this species. Northern analysis demonstrated a zebrafish p53-related transcript to be present and most abundant in zygotes and early-cleavage embryos less than 1 hour after fertilization, thereafter declining to barely detectable levels at 48 hours. A similar temporal expression was detected for the zebrafish L-myc, known to be present in maternally derived RNA, whereas zebrafish N-myc and the zebrafish homologue of the murine T gene were not detectable prior to the onset of zygotic transcription.

Alternative Splicing↗
PubMed1997

[The study of enhancement effect on wound healing from acid/heat stable peptides derived from pig serum].

It was reported in this article that a preparation of acid/heat-stable peptides (AHSP) from pig serum with a molecular-weight less than 18 ku a without antigenity and toxicity could exert enhancement effect on wound healing. Two pieces of polyvinyl alcohol (PVA) sponge implanted in rat dorsal subcutaneous pouchs of 20 mice were selected as the wound model. The subcutaneous pouch having one piece of sponge was taken as the experimental group and the other as the control. Injection of 50 microliters of such peptide preparation into the test sponge was performed once a day from the time of injury on for 5 consecutive times, while 50 microliters of BSA (5 mg/ml) into the control sponge in the same way. The levels of total DNA, protein and hydroproline in AHSP-treated sponge were observed significantly higher than those in the control sponge on the 7th and 10th days after wounding (P < 0.05). No significant difference was seen on the 14th postinjury day (P > 0.05). The effect of AHSP on proliferation of wound fibroblast cultured in vitro was also detected. In conclusion, such peptides derived from pig serum had the activity to accelerate wound healing without resultant excessive healing and its direct stimulation of the proliferation of wound fibroblast was probably one of the way which AHSP exerted its action.

Animals↗
PubMed1997

[Comparative study of expression of p21 and c-myc protein in hepatocellular carcinoma with pericarcinomatous liver tissue].

Expression of p21 and c-myc protein in hepatocellular carcinomas and their surrounding liver tissue was detected on serial sections by immunohistochemical method. The results showed that the positive rates of p21 expression were 53.3% (16/30) and 96.7% (29/30) in hepatocellular carcinomas and pericarcinomatous liver tissue, and 40% (12/30) and 86.7% (26/30) and 86.7% (26/30) for c-myc protein expression respectively. Their incidences in pericarcinomatous liver tissue were higher than that in cancer tissue (P < 0.01). The patterns of p21 and c-myc protein in cells were cytoplasm, membrane and/or nuclear types. Their expression was more intensive in pericarcinomatous hepatocytes, especially in liver cirrhosis nodes. The results indicate that abnormal activiation and expression of oncogene ras and c-myc may be related to hepatocellular carcinogenesis.

Adult↗
PubMed1996

Characterization of a human gene related to genes encoding somatostatin receptors.

We report the identification of a gene, named SLC-1(1), encoding a novel G protein-coupled receptor (GPCR). A customized search procedure of a database of expressed sequence tags (dbEST) retrieved a human cDNA sequence that partially encoded a GPCR. A genomic DNA fragment identical to the cDNA was obtained and used to screen a library to isolate the full-length coding region of the gene. This gene was intronless in its open reading frame, and encoded a receptor of 402 amino acids, and shared -40% amino acid identity in the transmembrane (TM) regions to the five known human somatostatin receptors. Northern blot analysis revealed that SLC-1 is expressed in human brain regions, including the forebrain and hypothalamus. Expression in the rat was highest in brain, followed by heart, kidney, and ovary. Expression of SLC-1 in COS-7 cells failed to show specific binding to radiolabelled Tyr1-somatostatin-14, naloxone, bremazocine, 1,3-di(2-tolyl)-guanidine (DTG), or haloperidol. A repeat polymorphism of the form (CA)n was discovered in the 5'-untranslated region (UTR) of the gene and SLC-1 was mapped to chromosome 22, q13.3.

Amino Acid Sequence↗
PubMed1996

A novel gene codes for a putative G protein-coupled receptor with an abundant expression in brain.

Following the cloning of the dopamine receptors we continued a search of the human genome for related genes. We searched an EST data base and discovered cDNA fragments encoding novel G protein-coupled receptor genes. The available GenBank sequence of one of these EST fragments showed that it encoded a receptor with closest similarity to the D2 dopamine and adrenergic receptors. This cDNA was used to isolate the gene (GPR19), and the encoded receptor also demonstrated similarity with the neuropeptide Y receptor. The gene was mapped to chromosome 12, in region p13.2-12.3. Northern blot analysis revealed expression of GPR19 in peripheral regions, and brain regions significantly overlapping with the D2 receptor gene expression. A sequence of the rat orthologue of GPR19 was obtained and in situ hybridization analysis demonstrated a very abundant expression in rat brain.

Amino Acid Sequence↗
PubMed1996

Screening of differentially amplified cDNA products from RNA arbitrarily primed PCR fingerprints using single strand conformation polymorphism (SSCP) gels.

Arbitrarily primed PCR fingerprinting of RNA and differential display resolved on an acrylamide gel has been extensively used to detect differentially expressed RNAs. However, after a differentially amplified product is detected the next steps are labor-intensive: a small portion of the fingerprinting gel that contains the differentially amplified product is cut out, reamplified and the correct product is determined, typically by cloning and sequencing what is often a mixture of products of similar size. Here we use a native acrylamide gel to separate DNAs in the reamplified mixture based on single-stranded conformation polymorphisms. Reamplifications are performed for the region carrying the differentially amplified product and a corresponding region from an adjacent lane where the product is less prominent or not visible. Denaturation of the reamplified DNA followed by side-by-side comparison on an SSCP gel allows the classification of reamplified material into (i) those that can be directly cloned because the differentially amplified product is relatively pure, (ii) those that need to be reamplified from the SSCP gel before cloning and (iii) those that are too complex for further study. This screen should save considerable effort now wasted on directly cloning unsuitable products from RNA fingerprinting experiments. An example is presented of cloning a gene differentially expressed in Trypanosoma brucei life cycle.

Acrylic Resins↗
PubMed1996

[CuZn-SOD determination of sera in patients with rheumatic diseases].

Superoxide anion (O2.-) plays an important part in reactive oxygen species (ROS). In order to explore its effect on the pathogenesis of rheumatic diseases, authors had determined CuZn-SOD contents of sera in 132 subjects involving the patients of rheumatic diseases (SLE, RA, etc), non-rheumatic diseases and normal controls by using enzyme linked immunosorbent assay (ELISA). The results showed the followings: CuZn-SOD contents of 27 normal subjects: 98.80 +/- 20.74 ng/ml (x +/- s); that of 27 non-rheumatic diseases cases: 72.24 +/- 16.60 ng/ml (x +/- s); of 22 SLE cases: 56.56 +/- 19.27 ng/ml (x +/- s); of 27 RA cases: 61.56 +/- 20.53 ng/ml (x +/- s); of 29 other rheumatic diseases cases: 68.97 +/- 17.79 ng/ml (x +/- s). Statistical test was made: both CuZn-SOD contents of rheumatic disease and non-rheumatic disease were lower than that of normal subjects with more significant difference (P < 0.001); compared with that of non-rheumatic diseases patients, SLE cases had significant difference (P < 0.01); RA cases had significant difference (P < 0.05); other cases of rheumatic diseases had no statistical differrence (P > 0.05). Above results suggest that superoxide anion is a non-specific inflammatory mediator which contributes to disorders with inflammatory damages (rheumatic or non-rheumatic diseases), where CuZn-SOD content tested was obviously lower than normal subjects; among the rheumatic disease patients, CuZn-SOD contents of the sera of SLE patients were the lowest because of its more autoimmune antibody, more severe inflammatory and immunological reaction. This work laid the theoretical and experimental foundation for the clinical application of exogenous CuZn-SOD in the treatment of rheumatic diseases. Combined use of CuZn-SOD scavengers may get better result because of the complexibility of ROS inflammatory mechanism.

Adolescent↗
PubMed1995

Cloning and chromosomal mapping of three novel genes, GPR9, GPR10, and GPR14, encoding receptors related to interleukin 8, neuropeptide Y, and somatostatin receptors.

We employed the polymerase chain reaction and genomic DNA library screening to clone novel human genes, GPR9 and GPR10, and a rat gene, GPR14. GPR9, GPR10, and GPR14 each encode G protein-coupled receptors. GPR10 and GPR14 are intronless within their coding regions, while GPR9 contains at least one intron. The receptor encoded by GPR9 shares the highest identity with human IL-8 receptor type B (38% overall and 53% in the transmembrane regions), followed by IL-8 receptor type A (36% overall and 51% in the transmembrane domains). GPR10 encodes a receptor that shares highest identity with the neuropeptide Y receptor (31% overall and 46% in the transmembrane domains). The receptor encoded by GPR14 shares highest identity with the somatostatin receptor SSTR 4 (27% overall and 41% in the transmembrane domains). Fluorescence in situ hybridization analysis localized GPR9 to chromosome 8p11.2-p12 and GPR10 to chromosome 10q25.3-q26.

Amino Acid Sequence↗
PubMed1995

The cloning and chromosomal mapping of two novel human opioid-somatostatin-like receptor genes, GPR7 and GPR8, expressed in discrete areas of the brain.

Following the cloning of the opioid receptors mu, kappa, and delta, we conducted a search for related receptors. Using oligonucleotides based on the opioid and also the structurally related somatostatin receptors, we amplified genomic DNA using the polymerase chain reaction and isolated fragments of novel G protein-coupled receptor genes. Two of these gene fragments designated clones 12 and 11 were used to isolate the full-length genes. The intronless coding sequences of these genes, named GPR7 and GPR8, shared 70% identity with each other, and each shared significant similarity with the sequences encoding transmembrane regions of the opioid and somatostatin receptors. GPR7 was mapped to chromosome 10q11.2-q21.1 and GPR8 to chromosome 20q13.3. Northern blot analysis using human mRNA demonstrated expression of GPR7 mainly in cerebellum and frontal cortex, while GPR8 was located mainly in the frontal cortex. In situ hybridization revealed expression of GPR7 in the human pituitary. A partial sequence of the mouse orthologue of GPR7 was obtained, and in situ hybridization demonstrated expression in discrete nuclei of brain, namely suprachiasmatic, arcuate, and ventromedial nuclei of hypothalamus. A stable cell line expressing the GPR7 gene was created, but expression levels of the receptor were low. The available pharmacology indicated binding to several opioid drugs such as bremazocine, levorphanol, and beta-FNA, but not to the opioid receptor subtype-selective mu, delta, or kappa agonists.

Amino Acid Sequence↗
PubMed1995

Isolation of three novel human genes encoding G protein-coupled receptors.

We have cloned and mapped the chromosomal location of three novel human genes encoding G protein-coupled receptors that we have named GPR6, GPR5, and GPR4. The entire coding region for each of these genes was contained on single exons. Gene GPR6 encoded a receptor that shared closest identity (71% in the transmembrane regions) with the human orphan receptor GPR3 and was localized to chromosome 6 (q21-q22.1). Northern blot analysis revealed that GPR6 transcripts were abundant in the human putamen and to a lesser extent in the frontal cortex, hippocampus, and hypothalamus. Gene GPR5 encoded a receptor that most closely resembled the orphan receptor RBS11 (48% in the transmembrane regions) and the MIP 1 alpha/RANTES receptor (45% in the transmembrane regions) and was localized to chromosome 3 (p21.3-p21.1). Gene GPR4 shared identity (40% in the transmembrane regions) with the human platelet-activating factor receptor and was localized to chromosome 19 (q13.2-q13.3).

Amino Acid Sequence↗