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Biomedical subjects

Y Wan

Publications and source records attributed to Y Wan.

At least 127 records · Page 7Linked to original sources
PubMed1996

An improved green fluorescent protein gene as a vital marker in plants.

A synthetic green fluorescent protein (GFP) gene (pgfp) was constructed to improve GFP expression in plants. Corn and tobacco protoplast transient assays showed that pgfp gave about 20-fold brighter fluorescence than the wild-type gene (gfp). Replacement of the serine at position 65 with a threonine (S65Tpgfp) or a cysteine (S65Cpgfp) yielded 100- to 120-fold brighter fluorescence than wild-type gfp upon excitation with 490-nm light. Incorporation of a plant intron into the coding region yielded an additional 1.4-fold improvement, for a cumulative improvement of about 150-fold in fluorescence at 490-nm excitation. Various versions of pgfp were also stably introduced into corn, wheat, tobacco, and Arabidopsis plants. Bright-green fluorescence was observed with a fluorescence microscope in virtually all examined tissues of transgenic monocots and dicots. In the case of Arabidopsis, expression of the pgfp gene under the enhanced 355 promoter of the cauliflower mosaic virus produced green fluorescence that was readily detectable by eye using a hand-held, long-wave ultraviolet lamp and/or a black-light source.

Amino Acid Sequence↗
PubMed1996

Adenoviral gene transfer of macrophage inflammatory protein-2 in rat lung.

Replication-defective adenoviral vectors are capable of localized transfer and expression of incorporated gene product in lung tissue. We have constructed an adenoviral vector that expresses rat macrophage inflammatory protein (MIP)-2, a C-X-C chemokine specifically chemotactic for neutrophils, Supernatants from 293 cells, infected with the adenoviral MIP-2 (ADMIP-2) construct, showed potent chemotactic activity and the ability of the ADMIP-2 vector to transcribe and make functional protein was confirmed. In vivo analysis of bronchoalveolar lavage fluid from rats after intratracheal instillation of ADMIP-2 (10(9) plaque-forming units) showed a 10-fold increase in the absolute number of neutrophils in bronchoalveolar lavage fluid as opposed to rats treated with an equal titer of an E1-disabled control virus expressing firefly luciferase (ADCA-18). Neutrophils constituted 65% of total BAL cells with alveolar macrophages being the other major cell type recovered. Rat MIP-2 protein was increased (nanograms per milliliter) in bronchoalveolar lavage fluid over a period of 7 days in ADMIP-2-treated animals. MIP-2 mRNA was demonstrated by Northern blot analysis in lung tissue, and histological analysis confirmed the presence of massive localized tissue neutrophilia. Evidence of chronic tissue injury and repair (ie, fibrosis) was not detected up to 2 weeks after the neutrophil infiltrate had resolved, subsequent to decreased chemokine presence. Adenoviral gene transfer proved an effective tool for the assessment of lung tissue expression of this chemokine in vivo and is useful in developing rodent models of tissue neutrophilia.

Adenoviridae↗
PubMed1996

Inhibitory effect of cholesterol oxides on low density lipoprotein receptor gene expression.

The effects of the cholesterol oxides on low density lipoprotein receptor (LDLR) gene expression were investigated. Cultured rabbit aortic smooth muscle cells were incubated with 1, 2, and 5 micrograms/ml culture medium concentrations of pure cholesterol, 25-hydroxycholesterol (25-OH), 7-ketocholesterol (7-keto), cholestane-3 beta, 5 alpha, 6 beta-triol (triol) and cholesterol-5 alpha, 6 alpha-epoxide (epoxide) for 12 hours and with vehicle only as control. Total mRNAs were extracted and electrophoresed. Northern blot hybridization analyses were performed. The results showed mRNA expressions of LDLR gene were inhibited to 16.1 +/- 4.4%, 33.8 +/- 0.6%, 42.8 +/- 1.8% and 46.9 +/- 3.9% of control by 25-OH, 7-keto, epoxide and triol respectively. Pure cholesterol showed only minimal inhibition. The inhibitions were time dependent. Although cholesterol oxides have been shown to alter many membrane-related functions and the LDLR domain are located in the cell membrane. The findings of this study suggested that the cholesterol oxides exerted their repressive actions on LDLR function primarily by down-regulating LDLR gene expression rather than directly upon cell membrane.

Animals↗
PubMed1996

[Loss of heterozygosity involving DCC gene in human colorectal cancers is correlated with the metastatic potential].

DCC gene located at chromosome 18q21.3 is an important tumor-supressor gene associated with tumorigenesis and progression, especially in colorectal carcinomas. Adopting Southern blot technique and RFLP analysis, 33 primary Chinese colorectal cancer patients were examined for loss of heterozygosity (LOH) of DCC gene. Among 16 informative cases, 6 (38%) showed allelic deletion. 18q LOH was correlated with lymph node and hepatic metastases (P < 0.05). The results indicate that application of molecular genetics is of value in ascertaining the metastatic potential of colorectal carcinomas.

Adult↗
PubMed1996

[Renin-angiotension system--stress hormone response system].

Angiotensin II (A II) was significantly increased in both acutely and chronically stressed animals as found in brain, heart, blood vessels and adrenal glands. After running a race, the plasma A II contents of sportsmen similar to cortisol increased markedly too. In the chronical stress-hypertensive animals, the contents of circulating A II and tissue A II were increased quite lastingly. It was also found that the high concentration of A II may stimulate the adrenal gland secreting glucosteroid, and increase of tissue A II may be faciliated by the activation of beta adrenergic receptors. On basis of the above finding, we tend to assume that A II is a stress hormone and the renin angiotension system (RAS) is a stress hormone responses system. Morever there exists a close relation between RAS and two classic stress hormone response systems, i.e. the hypothalamus-pituitary-adrenal cortex system and the sympathetic-adrenal medulla system.

Angiotensin II↗
PubMed1996

[Research progress on the glia cell line-derived neurotrophic factor].

Glia cell line-derived neurotrophic factor (GDNF) is a novel type of neurotrophic factor cloned in 1993. Recent research revealed that it may have potential application in the treatment of Parkinson's disease and motor neuron diseases. This short review summarized the character of the protein, gene structure, tissue distribution, and its physiological functions and pathological implications.

Animals↗
PubMed1995

Identification of donor-derived dendritic cell progenitors in bone marrow of spontaneously tolerant liver allograft recipients.

Multilineage donor-derived hematopoietic cell chimerism is a persistent feature of spontaneously tolerant mouse liver allograft recipients. We have shown previously that normal liver-derived precursors of "chimeric" dendritic cells (DC) propagated in vitro migrate in vivo to T-dependent areas of allogeneic lymphoid tissue, where they or their progeny appear to persist indefinitely. In this study, granulocyte-macrophage colony-stimulating factor (GM-CSF)+interleukin-4 (IL-4) were used to propagate DC progenitors from freshly isolated mouse bone marrow. The progenitor cells gave rise in 7-10 days to potent antigen-presenting cells (APC) that stimulated naive allogeneic T cells in primary mixed leukocyte cultures (MLC). The culture method, together with the reverse transcriptase-polymerase chain reaction (RT-PCR) for the detection of donor and recipient strain major histocompatibility complex (MHC) class II mRNA was used to test whether donor-derived DC could be propagated from the bone marrow of unmodified, orthotopic liver allograft recipients. Freshly isolated bone marrow from these transplanted animals contained small numbers of donor cells and responded to GM-CSF+IL-4 stimulation. In addition to cells expressing recipient (B10) phenotype (H-2Kb+; Iab+), a minor population of donor (B10.BR)-derived cells (H-2Kk+; Iak) were also propagated from liver graft recipients euthanized two weeks posttransplant. DC sorted from these cultures exhibited stimulatory activity for recipient strain T cells consistent with a low level (< 1%) of donor DC propagation. The immunologic role of donor-derived DC progenitors in liver allograft recipients and its relation to the induction and maintenance of donor-specific unresponsiveness remains to be determined.

Animals↗
PubMed1995

Activation of Tsk and Btk tyrosine kinases by G protein beta gamma subunits.

Tsk/Itk and Btk are members of the pleckstrin-homology (PH) domain-containing tyrosine kinase family. The PH domain has been demonstrated to be able to interact with beta gamma subunits of heterotrimeric guanine nucleotide-binding proteins (G proteins) (G beta gamma) and phospholipids. Using cotransfection assays, we show here that the kinase activities of Tsk and Btk are stimulated by certain G beta gamma subunits. Furthermore, using an in vitro reconstitution assay with purified bovine brain G beta gamma subunits and the immunoprecipitated Tsk, we find that Tsk kinase activity is increased by G beta gamma subunits and another membrane factor(s). These results indicate that this family of tyrosine kinases could be an effector of heterotrimeric G proteins.

Agammaglobulinaemia Tyrosine Kinase↗
PubMed1995

Linear aggregations of stomata and epidermal cells in Tradescantia leaves: evidence for their group patterning as a function of the cell cycle.

We tested Charlton's hypothesis (1990) that stomata are present and patterned in linear cell aggregations using the monocot Tradescantia. We examined the following features of the leaf epidermis in support of this theory: linear groups (strings) of stomatal complexes and of epidermal cells were sought in immature and mature regions of entire leaves; the lengths (in cell number) and incidences (numerical occurrence) of both string types were determined; the uniformity and progression of stomatal differentiation within strings were studied; physical characteristics of differentiating strings within cell files were measured. Undifferentiated epidermal cells from the leaf base were stained with DAPI to reveal precursors of stomatal strings immediately proximal to the stomatal initial region. The results indicated that the Tradescantia epidermis in the leaf blade consists of linear groups of stomata and epidermal cells, which did not change in cell number nor incidence during development. The incidence of stomata by length was nonrandom. Although incidence decreased with string length, the decline was not linear nor exponential. Stomatal strings show cell cycle synchrony in DAPI staining of stomatal precursors and synchrony of stomatal differentiation within a string. The irregularity in the length of the stomatal development region, and each differentiation stage in it, by cell file was consistent with the variation in string length and unity in string development. The evidence supports Charlton's hypothesis that cells are patterned based on their position in the cell cycle and that linear groups of stomata reflect cell lineages, which maintain a degree of cell cycle synchrony.

Cell Aggregation↗
PubMed1995

Differences in colorectal cancer between China and Japan: a clinical and histological study of two groups of cases.

It is well known that most tumours are attributed to life style, especially the tumours of the digestive system. Clinical and histopathological investigation of tumours in different human groups and societies, and analysis of the variations will provide evidence for this, and is one of the approaches to study carcinogens. Clinical data obtained from 391 patients with colorectal cancer at the Sakai Municipal Hospital, Japan, and Shanghai Jinshan Hospital and Cancer Hospital, China, from 1987 to 1992, included the sex, age and tumour subsite. Sections of histological specimens were also retrieved. The results were compared between two countries. The average age of patients with colorectal cancer in Shanghai was 8.5 years less than in the Sakai group. The age peak of the former was 51-60, and in the latter, 61-70 years. The most frequent site of the cancer in the Shanghai group was the rectum, contrasting with the higher percentage of sigmoid colon cancer in Sakai group. There was also a significant difference in histological subtype of the cancer between the two groups. Mucinous adenocarcinoma was notably more common in the Shanghai group than in the Sakai group, and the high frequency was mainly in the colon. All of the variations were suggested to be attributable to differing socioeconomic circumstances and lifestyle, especially the dietary habits of the countries.

Adult↗
PubMed1995

Role of lipopolysaccharide (LPS), interleukin-1, interleukin-6, tumor necrosis factor, and dexamethasone in regulation of LPS-binding protein expression in normal hepatocytes and hepatocytes from LPS-treated rats.

Lipopolysaccharide (LPS)-binding protein (LBP) has been reported to be an acute-phase protein. LBP binds to LPS with a high affinity; LPS-LBP complexes then interact with the receptor CD14, resulting in increased expression of LPS-inducible genes. Hepatocytes represent a major source of LBP, but little is known about the regulation of rodent hepatocyte LBP synthesis. In these studies, undertaken to characterize hepatocyte LBP expression, we show that greater-than-20-fold increases in LBP mRNA levels in hepatocytes occurred following injection of LPS or turpentine in rats. In primary cultures of rat hepatocytes, the addition of interleukin-6 (IL-6) and LPS led to 4.5- and 3.2-fold stimulation in LBP mRNA levels, respectively. The induction of LBP by IL-6 or LPS was attenuated by dexamethasone. In contrast to IL-6 and LPS, in the presence of 10(-6) M dexamethasone, IL-1 and tumor necrosis factor (TNF) led to maximal LBP mRNA induction levels, 4.7- and 3.8-fold, respectively, suggesting that IL-6 and LPS stimulate LBP expression by mechanisms different from those of IL-1 and TNF. Similar induction levels of LBP mRNA were seen in rat H35 hepatoma cells for all four stimuli, and dexamethasone inhibited these responses. Dexamethasone alone increased the spontaneous induction in primary hepatocytes at early time points but suppressed induction at later time points. Furthermore, hepatocytes from rats treated with LPS in vivo exhibited a > 10-fold increase in mRNA expression in response to LPS and enhanced responses to TNF and IL-1. As with the normal hepatocytes, dexamethasone inhibited the LPS-dependent induction in the LPS-treated rat hepatocytes. These data suggest that LBP synthesis by hepatocytes is under the control of LPS, IL-1, TNF, IL-6, and glucocorticoids and that the LPS treatment primes hepatocytes for subsequent responses to LPS, TNF, and IL-1 for LBP synthesis.

Acute-Phase Proteins↗
PubMed1995

[The diagnosis and treatment of focalized pancreatitis: report of 16 cases].

We report 16 patients of focalized pancreatitis. All patients presented mass in the head of pancreas and obstructive jaundice (13 patients), characterized by spontaneous mass shrinkage and jaundice subsidence within two weeks after admission without any surgical intervention. Sonography, ERCP, exploration and intraoperative biopsy are of value in differentiating FP from carcinoma. Six patients received conservative therapy. Operations aimed to drain the commonbile duct and pancreatic duct (T tube drainage of commonbile duct, choledochojejunostomy, pancretojejunostomy) were performed in 7 patients. Pancretoduodenectomy were performed in 3 patients on tentative diagnosis of carcinoma in the head of the pancreas. Follow-up in 12 patients showed satisfactory results.

Choledochostomy↗
PubMed1995

[p53 gene point mutation in human colorectal carcinoma].

We introduced two modified assay systems, PCR-SSCP and PCR-direct sequencing for the identification of structure aberration at p53 exon 7 in 22 colorectal carcinomas and 1 metastatic lymph node. The data indicated that 27.2% (6/22) colorectal carcinomas and one metastatic lymph node were shown to contain the point mutations in codons 245, 251, 259 and 260 of exon 7. One half of all the mutations was G:c to A:T transition in codon 245. Other mutation patterns were base insertion and deletion. All positive point mutations of p53 exon 7 existed in colon carcinomas in this study. The point mutation in p53 exon 7 was usually associated with poorly differentiated primary carcinomas (P = 0.0178) and the mutation rate of was higher in Duckes C stage of the disease than in stage Duckes A and B (P = 0.0361). Thus p53 exon 7 point mutation in primary colorectal tumors and regional lymph nodes may identity a subgroup of colorectal cancer patients with more aggressive disease and may be as a new tumor markers for assessing the prognosis of colorectal carcinomas.

Adult↗
PubMed1995

[Total pelvic exenteration for local advanced rectal carcinoma: analysis of 20 patients].

20 patients of total pelvic extenteration (TPE) were performed from 1989 to 1995 for local advanced rectal carcinoma. The incidence of operative complications was 65% with a mortality of 5%. 19 patients were followed up for 3-42 months, 7 patients died with an average life-span of 14.1 months. It seemed to us that the results of conservative therapy was usually disappointing for local advanced rectal carcinoma and and TPE is the better management of choice for relieving patient's symptoms and improving their survival rates.

Adenocarcinoma↗
PubMed1995

[Significance of diagnosis and prognosis for breast carcinoma with examination of Ag-NORs].

The argyrophilic nucleolar organizer regions (Ag-NORs) was measured in the tissue sample aspirated with fine needle for 17 cases of breast benign lesion and 46 cases of breast cancer, by analysis of their micro-image with light microscope and computed. The results indicated that the amount of Ag-NORs in the nuclei of breast cancer was increased while the percentage of average areas occupied by Ag-NORs was decreased. It was significant statistically in comparing with benign lesion (P < 0.05). In addition, the amount of Ag-NORs in the nuclei of breast cancer with and that without metastasis was not different markedly (P > 0.05). However the percentage of average areas occupied by Ag-NORs was different statistically (P < 0.05). The conclusion of Ag-NORs is of benefit to distinguish from benign and malignant tumours of breast as well as significant for evaluating the prognosis for breast cancer.

Adenoma↗