Search PubMed⌕ Search

Biomedical subjects

Q Shen

Publications and source records attributed to Q Shen.

At least 145 records · Page 8Linked to original sources
PubMed1994

Cloning of polygalacturonase (PG) cDNA and inhibition effects of its antisense RNA on the expression of PG gene in transgenic tomato plants.

We have amplified a 1.5-kb PG cDNA including its complete open reading frame, using two primers specific to PG gene and PCR technique. Its fidelity and correctness were confirmed by restriction mapping and partial DNA sequencing. The PG gene was then inserted into a binary vector, pBin437, in an inverted orientation between the 35S promoter with duplicated enhancers and the Nos3' transcriptional termination sequence, and the resulting plasmid pBPG was introduced into LBA 4404. The A. tumefaciens harboring pBPG was used to transform tomato plants. Sixty kanamycin-resistant transformants were selected. PCR detection showed two-third of the transformed plants tested (30 plants) contain the exogenous PG gene. The PG activity assay and SDS-PAGE analysis of proteins from ripening fruit cell wall showed that the PG activity in transgenic tomato plants were inhibited in different extent. One of them, plant 3, gave only 7% PG activity compared with the control (100%). These results suggest that the expression of the anti-PG gene has effectively inhibited the expression of endogenous PG gene. The effect of low-level PG activity on tomato fruit ripening and storage is being investigated.

Base Sequence↗
PubMed1994

[Culture of cartilaginoid tissue reconstituted by chondrocytes embedded within collagen gels].

Chondrocytes from the sterna of embryonal chicken were dissociated by enzymatic digestion. Dissociated cells were cultured within collagen gels for 8 days. The cells increased 3 fold in 8 days. The gels gradually became white cartilaginoid tissue in appearance. Morphologic study showed that cells lied in lacunae and maintained the differentiated characteristics of cartilage. Extracellular matrix produced by cells deposited on exogenous collagen. Biochemical analysis showed that the collagen newly synthesised by the cells was type II collagen. This experiment demonstrates that collagen gels provide a suitable environment for chondrocyte growth, proliferation and differentiation, and chondrocytes embedded within collagen gels reconstitute cartilaginoid tissue.

Animals↗
PubMed1994

[Expression and significance of immunosuppressive acidic protein (IAP) in human esophageal squamous cell carcinoma].

The expression of IAP in the esophageal tissues of 74 patients with esophageal squamous cell carcinoma and 12 normal controls were determined by using MI2, and anti-IAP monoclonal antibody, and ABC immunohistochemical staining. The results showed that there was no expression of IAP in normal esophageal epithelium of all control subjects, and the positive rate in specimens of the esophageal carcinomas was 90.3% (P < 0.001). The staining intensity of IAP was increasing with the decrease in degrees of cell differentiation of the tumors (P < 0.05). The expression of IAP in long survivors without lymph node metastasis were lower than that in cases with metastasis (P < 0.005) and short survivors (P < 0.001). The results suggest that IAP may play an important role in tumor cell differentiation, clinical course and prognosis of esophageal carcinoma, and may be used as a tumor marker for the diagnosis of this malignancy.

Antibodies, Monoclonal↗
PubMed1994

[Nucleic acid hybridization technique detection of enterovirus RNA in myocarditis].

Forty five specimens from human myocarditic or myopathic tissues were examined for enteroviruses by in situ hybridization with 2 biotin labelled generic enterovirus probes pCBIII/35 and pCBIII/51. Positive hybridization signals were obtained in 12 samples (26.6%). Enterovirus RNA were obtained in 5 out of these 12 samples (41.7%) by the presence of positive hybridization signals with a coxsackie B3 virus type-specific probe pCBIII/29. The positive hybridization signals were primarily localized within the cytoplasm of single or several myocytes and the myocardial interstitial tissues, and were also occasionally seen within the cytoplasm of endotheliocytes of blood vessels in the myocardium.

Cardiomyopathy, Dilated↗
PubMed1994

Regulatory action of Astragalus saponins and buzhong yiqi compound on synthesis of nicotinic acetylcholine receptor antibody in vitro for myasthenia gravis.

With overall analysis of symptoms and signs of myasthenia gravis (MG) basing on "Pi (Spleen) Deficiency" [symbol: see text] theory and with years of our clinical experience in treating MG, we performed a pharmacological study of Astragalus saponins and Buzhong Yiqi Compound (Tonic granulae invigorating vital energy) in 14 peripheral blood mononuclear cell (PBMNC) cultures from 10 MG patients. PBMNG from two groups of patients given dexamethasone (Dxm) and cobalt 60 (60Co) treatment were used as controls. The results showed that water soluble Astragalus saponins significantly reduced the titer of nicotinic acetylcholine receptor antibodies (nAchR-Ab) in the cell culture supernatants, from 418.8-2328 to nil in 6 cases, and from 1143-1235 to 43-157 fmol/ml in 2 cases, and that Buzhong Yiqi compound also had inhibitory immunoregulatory action.

Adolescent↗
PubMed1993

Hormone response complex in a novel abscisic acid and cycloheximide-inducible barley gene.

The phytohormone, abscisic acid (ABA), plays a variety of roles during seed development and in the plant's response to environmental stresses. To study the molecular action of ABA, we have isolated a single copy ABA-induced gene, HVA22, which is mapped to barley chromosome 1. The HVA22 gene can be induced by either ABA or the protein synthesis inhibitor, cycloheximide, and addition of both inducers to barley aleurone layers has a synergistic effect on the expression of this gene. Sequence comparison indicates that the HVA22 gene product is highly homologous to the product of human DP1 gene, which is likely to contribute to colorectal tumorigenesis. The hormonal regulation of HVA22 expression has been studied, and there appear to be at least three elements, two located in the promoter and one in the first intron, which are essential for the high level of ABA induction of HVA22 expression. Among the promoter elements is a homolog of ABA response element, which has been shown to be important in the expression of other ABA-induced genes in plants. We suggest that the barley HVA22 gene product is likely a regulatory protein, and the ABA induction of this gene requires the action of a complex set of hormone response elements.

Abscisic Acid↗
PubMed1993

Screening for human papillomavirus infections in esophageal squamous cell carcinomas by in situ hybridization.

BACKGROUND: Infections with specific types of human papillomavirus (HPV) have been closely linked with human squamous cell carcinomas, those of the anogenital tract in particular. Increasing number of reports also suggest that HPV infection could be a risk factor for esophageal cancer. However, most of the previous studies on HPV involvement in esophageal carcinomas have included only small numbers of biopsy specimens, thus necessitating additional studies based on extensive series of esophageal samples. METHODS: A series of 776 biopsy specimens derived from 363 patients who had undergone esophagectomy for squamous cell carcinoma in the high-incidence area of China were analyzed for the presence of HPV DNA by screening and specific typing in situ hybridization with biotinylated HPV DNA probes. RESULTS: Under low-stringency conditions, 85 (23.4%) tumors were demonstrated to contain HPV DNA: Positive signals were found on the nuclei of cancer cells in 71 (19.6%), in the surrounding epithelial cells with hyperplastic or dysplastic changes in 13 (3.6%), in the cancer cells and the surrounding epithelial cells in 10 (2.8%), and in the resected margins in 1 (0.3%). Thirty-four (40%) of the 85 HPV-positive tumors were shown to contain at least one type of HPV 6, 11, 16, 18, or 30 DNA sequences. HPV 16 was the type found most frequently, occurring in 18.8% of the 85 HPV-positive specimens. In addition to the primary tumors, HPV DNA sequences were found in 12.3% (7 of 57) of the lymph node metastases. CONCLUSION: The results confirm the previously reported HPV involvement in esophageal squamous cell lesions and implicate HPV as a potential etiologic agent in the multifactorial pathogenesis of esophageal carcinoma.

Adult↗
PubMed1993

Nutrition intervention trials in Linxian, China: multiple vitamin/mineral supplementation, cancer incidence, and disease-specific mortality among adults with esophageal dysplasia.

BACKGROUND: A number of vitamins and minerals have been shown to influence carcinogenesis in experimental animals. In humans, epidemiologic evidence suggests that intake of fruits and vegetables may reduce risk of esophageal and other cancers. Vitamins and minerals in these foods may contribute to the reduced cancer risk. The people of Linxian, China, have persistently low intake of multiple nutrients and exhibit one of the world's highest rates of esophageal/gastric cardia cancer, with an exceptionally high risk of esophageal dysplasia. PURPOSE: To determine whether supplementation with multiple vitamins and minerals may reduce esophageal/gastric cardia cancer among persons with esophageal dysplasia, we conducted a 6-year prospective intervention trial in Linxian. METHODS: Mortality and cancer incidence were ascertained from May 1985 through May 1991 for 3318 persons with cytologic evidence of esophageal dysplasia who were randomly assigned to receive, throughout that period, daily supplementation with 14 vitamins and 12 minerals or placebo. Doses were typically two to three times U.S. Recommended Daily Allowances. Compliance was assessed by counting unused pills monthly for all trial participants and by assaying nutrient levels in blood collected from samples of individuals randomly selected without replacement every 3 months throughout the trial. Cancers were identified through routine surveillance and by special cytology and endoscopy screenings after 2 1/2 years and 6 years. RESULTS: A total of 324 deaths occurred during the 6-year intervention period; 167 occurred in the control (placebo) group and 157 occurred in the supplement group. Cancer was the leading cause of death (54% of all deaths); 18% were due to cerebrovascular diseases and 29% to other causes. Cumulative esophageal/gastric cardia death rates were 8% lower (relative risk [RR] = 0.92; 95% confidence interval [CI] = 0.67-1.28) among individuals receiving supplements rather than placebo, a nonsignificant (P > .10) difference. Risk of total mortality was 7% lower (RR = 0.93; 95% CI = 0.75-1.16; P > .10), total cancer 4% lower (RR = 0.96; 95% CI = 0.71-1.29; P > .10), cerebrovascular disease 38% lower (RR = 0.62; 95% CI = 0.37-1.06; P = .08), and other diseases 12% higher (RR = 1.12; 95% CI = 0.74-1.69; P > .10) among the treated group. Cumulative cancer incidence rates were nearly the same in the two groups. CONCLUSIONS: No substantial short-term beneficial effect on incidence or mortality for this type of cancer occurred following daily supplementation with multiple vitamins and minerals among adults with precancerous lesions of the esophagus. IMPLICATIONS: Although no statistically significant short-term benefits were observed, longer follow-up should be more informative about the effectiveness of this 6-year supplementation on cancer and other diseases among individuals with esophageal dysplasia.

Adult↗
PubMed1993

Sequences in the 3'-untranslated region of the human cellular glutathione peroxidase gene are necessary and sufficient for selenocysteine incorporation at the UGA codon.

Glutathione peroxidase (EC 1.11.1.9) is one of a unique group of prokaryotic and eukaryotic enzymes that contain the unusual amino acid selenocysteine. The genes for these selenoproteins encode for the atypical amino acid at a TGA codon (UGA in the mRNA transcripts), which normally functions as a termination signal. The present studies analyzed the functional importance of sequences in the coding and 3'-untranslated regions of transcripts of the primary human cellular glutathione peroxidase gene (GPX1) to the insertion of selenocysteine at this UGA codon. Deletions in potential stem-loop or hairpin structures in the coding region did not substantially diminish incorporation of selenocysteine into glutathione peroxidase transiently expressed by the pCMV4 vector in COS-1 cells. However, selenocysteine insertion was completely abolished by deletion of four-nucleotide sequences in the 3'-untranslated region from within a conserved "selenocysteine insertion sequence" motif also found in the 3'-untranslated region of mammalian genes for other selenoproteins. Moreover, in constructs fusing the glutathione peroxidase 3'-untranslated region to the coding region of rab5b (an unrelated protein normally without any selenium moiety), the glutathione peroxidase 3'-untranslated region was sufficient to direct the translation of an opal (UGA) mutation as selenocysteine. Thus, our data directly demonstrate the importance of the selenocysteine insertion motif in the glutathione peroxidase gene and specifically show that sequence elements in the 3'-untranslated region are both necessary and sufficient for translational insertion of selenocysteine at a UGA codon in eukaryotic mRNA.

Animals↗
PubMed1993

Retrospective cohort study of risk-factors for esophageal cancer in Linxian, People's Republic of China.

A retrospective cohort study of esophageal (including gastric cardia) cancer was conducted to examine dietary and other potential risk factors in Linxian, a high-risk area in P.R. China. Study subjects were identified based on participation in a cytology examination conducted in 1974. They were interviewed in 1989 to obtain information on esophageal cancer risk-factors and identify new cases and deaths. A total of 1,162 subjects from the analytic cohort of 12,693 were determined to have developed esophageal cancer over the 15-year follow-up period. Results indicate that increased age, male gender, a positive family history, low education level, surface-water use, and pork consumption were the strongest risk factors for esophageal cancer identified in this cohort, while use of corn as a primary staple and infrequent consumption of fresh vegetables also were possible risk factors. Traditional or suspected risk factors for esophageal cancer in this and other populations--smoking and alcohol use, and pickled vegetable and moldy food consumption--were not risk factors in this study. Some variation in risk was seen based on the subject's cytology result from 1974. We conclude that dietary factors appear to play a role in the etiology of esophageal cancer in this high-risk population, but are less important than other constitutional factors such as age, gender, and family history.

Adult↗
PubMed1993

[Effect of photosensitized oxidation auto-hemotherapy with buyang huanwu tang on sequela of apoplexy].

An effective therapy in treating sequela of apoplexy (SA) was reported, 115 patients were divided semi-randomly into three groups: group T for treatment, both group A and B for control. Patients in group T received Photosensitized Oxidation Auto-Hemotherapy (POAH) with Buyang Huanwu Tang therapy, group A received POAH only, while in group B, conventional treatment were conducted. Clinical data were collected based on pre- and post-treatment qualified procedures according to "The Advice For Clinical Study on Apoplexy", complemented by hemorheologic findings and examination of nail fold microcirculation. The results showed that there was significant difference between group T and group A or B (P < 0.05), among them, the effective rate in group T was 78.5%. Differences in hemorheology findings and examination of nail fold microcirculation were similar (P < 0.01).

Adult↗