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Biomedical subjects

W Dong

Publications and source records attributed to W Dong.

At least 109 records · Page 6Linked to original sources
PubMed1996

[Factors influencing long-term survival in patients with nonoperable lung cancer: an analysis by Cox model].

This paper reports a prospective survey of 173 patients with nonoperable lung cancer between January. 1, 1983 to March. 1, 1985. The follow-up rate was 97.7% over five years. Fourteen factors including sex, age, course of disease before treatment, clinical stage, performance status, size of mass, metastatic status, hemoglobin before treatment, short-term response to treatment and so on which might influence long term survival were studied by univariate analysis (Kruskal-Wallis test for Kaplan-Meier survival curve) and by multivariate analysis (Cox's proportional hazad model and audio-visual chart test for goodness of fit). Multivariate analysis using Cox's model revealed 6 significant prognostic factors: performance status, short-term response to treatment, clinical stage, hemoglobin before treatment, smoking index and method of treatment. The survival prediction equation was chi 2 = 72.14, nu = 6, P < 0.0001. The results indicate that the performance status and the CR rate of the initial treatment, among other things, is the major factors affecting prognosis.

Adenocarcinoma↗
PubMed1995

Co-activation of RanGTPase and inhibition of GTP dissociation by Ran-GTP binding protein RanBP1.

RCC1 (the regulator of chromosome condensation) stimulates guanine nucleotide dissociation on the Ras-related nuclear protein Ran. Both polypeptides are components of a regulatory pathway that has been implicated in regulating DNA replication, onset of and exit from mitosis, mRNA processing and transport, and import of proteins into the nucleus. In a search for further members of the RCC1-Ran signal pathway, we have identified proteins of 23, 45 and 300 kDa which tightly bind to Ran-GTP but not Ran-GDP. The purified soluble 23 kDa Ran binding protein RanBP1 does not activate RanGTPase, but increases GTP hydrolysis induced by the RanGTPase-activating protein RanGAP1 by an order of magnitude. In the absence of RanGAP, it strongly inhibits RCC1-induced exchange of Ran-bound GTP. In addition, it forms a stable complex with nucleotide-free RCC1-Ran. With these properties, it differs markedly from guanine diphosphate dissociation inhibitors which preferentially prevent the exchange of protein-bound GDP and in some cases were shown to inhibit GAP-induced GTP hydrolysis. RanBP1 is the first member of a new class of proteins regulating the binding and hydrolysis of GTP by Ras-related proteins.

Amino Acid Sequence↗
PubMed1995

Ubiquitin is attached to membranes of baculovirus particles by a novel type of phospholipid anchor.

Purified budded virions of Autographa californica nuclear polyhedrosis virus (AcNPV) contain abundant amounts of free ubiquitin, which has an altered electrophoretic mobility on SDS gels as compared with standard ubiquitin. Phase extraction of virion proteins with Triton X-114 indicated that the modified form of ubiquitin behaved as an integral membrane protein. The membrane-bound form of ubiquitin was labeled with both phosphate and palmitate, and its electrophoretic mobility was altered by treatment with phospholipase A2 and a phosphatidylcholine-specific phospholipase D. Mild trypsin digestion indicated that the acyl group was not linked to the C-terminus of the protein. Acylated ubiquitin could not be radiolabeled with a membrane-impermeable Bolton-Hunter reagent unless virus was pretreated with detergent. Together, these experiments suggest that ubiquitin is attached to the inner face of the viral membrane by a novel type of phospholipid anchor.

Amino Acid Sequence↗
PubMed1995

Matrix protein synthesis by glomerular mesangial cells in culture: effects of transforming growth factor beta (TGF beta) and platelet-derived growth factor (PDGF) on fibronectin and collagen type IV mRNA.

The pathogenesis of glomerular scarring is multifactional; recent evidence suggests that transforming growth factor beta (TGF beta), a pleiotropic cicatricial mediator, may promote mesangial sclerosis by enhancing the production of extracellular matrix proteins. We studied the effect of TGF beta 1 and TFG beta 2 on collagen type IV and fibronectin (FN) synthesis in human glomerular mesangial cells in culture (GMC). Two hours after addition of TGF beta, an up to twofold increase in abundance of collagen type IV mRNA was found, which further increased up to fivefold within 24 h. Addition of cycloheximide did not inhibit the TGF beta effect, but caused by itself an up to twofold increase in the abundance of collagen type IV mRNA after 2 h. Together with collagen mRNA, the mRNA for FN and for platelet-derived growth factor (PDGF) was also enhanced. PDGF was found to enhance abundance of the collagen type IV and fibronectin mRNA in GMC. A neutralizing antibody to PDGF or a PDGF-antisense oligonucleotide partly inhibited the TGF beta-induced increase of collagen type IV mRNA, suggesting that TGF beta can affect the collagen type IV synthesis not only directly but also indirectly via the synthesis of PDGF.

Base Sequence↗
PubMed1995

The distinct gene expression of the pro-hormone convertases in the rat heart suggests potential substrates.

The present study examined the distribution of the pro-hormone convertases PC1, PC2, furin, PACE4 and PC5 in the rat heart. Northern blot analysis of RNA extracted from cardiac tissues showed high levels of furin and PACE4 mRNA in the atria and ventricles, while PC5 mRNA was found to be expressed at high levels in the dorsal aorta. Although undetectable by Northern blot analysis, both PC1 and PC2 mRNA were detected by in situ hybridization and immunohistochemistry in discrete regions of the intracardiac para-aortic ganglia. In situ hybridization studies also showed that furin mRNA was observed in all cardiac tissues and cells, consistent with the previously reported ubiquitous expression of this gene. PACE4 mRNA was highly abundant in both the atria and ventricular cardiomyocytes, with low to undetectable levels observed in blood vessels. Finally, PC5 transcripts were expressed in the endothelial cells lining coronary vessels and the valve leaflets of the heart. The present localization studies in the heart and cardiac blood vessels suggests potential roles for each convertase in the processing of various neuropeptides, hormones and growth factors.

Amino Acid Sequence↗
PubMed1995

Changes in the serum concentrations of gonadotrophins and oestradiol in peripubertal Chinese Beijing black gilts.

Four gifts of the Chinese Beijing Black breed, all from the same litter, had their blood serum concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH) and oestrogens (E2) measured by radioimmunoassay at intervals of 20 days between the ages of 5 and 185 days. The concentrations of LH declined sharply between days 5 to 25 and remained low until rising again from day 85 and reaching a peak at day 105 before declining again and remaining constant. The concentrations of FSH increased from day 85, peaking at day 105, followed by a slow decline to day 185. Serum E2 concentrations were high at day 5 then decreased dramatically, but increased considerably at 185 days. These results are similar to those reported from European breeds.

Animals↗
PubMed1995

Failure to demonstrate a protein coat on enamel crystallites by morphological means.

Phosphotungstic acid (PTA) treatment of section of Epon-embedded enamel dissolves the crystallites and stains material postulated to be crystal-bound proteins. Alternative, capillarity forces within the channels left after crystallite removal may draw in PTA. This prediction was tested on three systems. (1) Protein free synthetic hydroxyapatite was embedded in Epon; treatment of thin sections with PTA removed most crystals, leaving empty holes outlined by stain that could not represent protein. (2) Sections of rat incisor enamel were treated with PTA and then re-embedded in Epon and sectioned at 90 degrees to the original plane. In these sections-of-section the cut ends of dissolved crystallite profiles were coated with stain. To determine if stained protein coats can be detected in the absence of the crystallite profiles, Epon sections were partially demineralized with formic acid, re-embedded in Epon and sections-of section were PTA treated. Previously extracted crystallites left no stained coats, and only the crystallites that were not removed by formic acid left PTA-stained outlines. (3) PTA-treated sections of dogfish shark enameloid were flooded with 5-nm colloidal gold particles and sections-of-section were prepared. The presence of gold particles on the section surface and in holes previously occupied by crystallites suggested that PTA solution could also be sucked into similar holes. It is concluded that PTA outlines are not crystal-bound proteins but artefacts caused by stain lining holes left in the section when the crystallites have been extracted.

Animals↗
PubMed1995

Mortality study of construction workers in the UK.

BACKGROUND: Construction is one of the most dangerous industries in the world. However, there has been little literature on occupational epidemiology in this field. A study of the mortality experience over a 13-year period among construction workers in the UK was carried out. METHOD: This was based on 15,007 death certificates of members of the Building and Civil Engineering Holiday and Benefit Scheme, who had died during 1975 to 1987 aged 20-64 years. Proportional mortality ratio (PMR) and mortality odds ratio techniques were used. RESULTS: Significantly elevated PMR were found for deaths from all cancers, including cancer of the lung and stomach, and for accidental deaths. Associations were demonstrated between several job categories and an increased risk of cancer mortality. Occupational exposures to hazardous substances may have contributed to the elevated cancer mortality, although the study findings should be interpreted with caution. Inadequate supervision of safety procedures, together with a high proportion of young and inexperienced workers, may be associated with the high number of accidental deaths. CONCLUSIONS: The results support the hypothesis that working in the construction industry is associated with a high risk for accidental death and probably also for malignant diseases including lung, mesothelium and stomach cancers. Further epidemiological studies among construction workers are needed to support policies aimed at improving occupational health, including the prevention of accidents.

Accidents, Occupational↗
PubMed1995

The lef-3 gene of Autographa californica nuclear polyhedrosis virus encodes a single-stranded DNA-binding protein.

The Autographa californica nuclear polyhedrosis virus (AcNPV) replicates in the nuclei of infected cells and encodes several proteins required for viral DNA replication. As a first step in the functional characterization of viral replication proteins, we purified a single-stranded DNA-binding protein (SSB) from AcNPV-infected insect cells. Nuclear extracts were chromatographed on single-stranded DNA agarose columns. An abundant protein with an apparent molecular weight of 43,000 was eluted from the columns at 0.9 to 1.0 M NaCl. This protein was not evident in extracts prepared from control cells, suggesting that the SSB was encoded by the virus. SSB bound to single-stranded DNA in solution, and binding was nonspecific with respect to base sequence, as single-stranded vector DNA competed as efficiently as single-stranded DNA containing the AcNPV origin of DNA replication. Competition binding experiments indicated that SSB showed a preference for single-stranded DNA over double-stranded DNA. To determine whether SSB was encoded by the lef-3 gene of AcNPV, the lef-3 open reading frame was cloned under the control of the bacteriophage T7 promoter. Immunochemical analyses indicated that LEF-3 produced in bacteria or in rabbit reticulocyte lysates specifically reacted with antiserum produced by immunization with purified SSB. Immunoblot analyses of infected cell extracts revealed that SSB/LEF-3 was detected by 4 h postinfection and accumulated through 48 h postinfection.

Animals↗
PubMed1995

c-KIT expression enhances the leukemogenic potential of 32D cells.

The growth of human leukemic cells in culture and in vivo is dependent upon the presence of hematopoietic growth factors. Most populations of human leukemic acute myeloblastic leukemia (AML) cells express c-Kit on their surface and respond to Kit ligand (KL) in culture. To determine if this interaction was of potential significance in vivo we used a mouse model system. 32D cells, a murine IL-3-dependent myeloid cell line, were rendered KL responsive by transfection of the murine c-Kit. After injection of 32D or 32D-Kit cells into syngeneic hosts, animals bearing 32D-Kit cells, but not 32D cells, became moribund and were killed. These animals had circulating leukemic blast cells, infiltration of bone marrow, spleen, brain, liver, lung, and kidney. Cells recovered from some of the animals continued to be dependent upon IL-3 or KL for growth while in other cases the cells were factor independent. This model illustrates that the constitutive expression of c-Kit enhances the leukemic potential of 32D cells. The model will be useful for studying the progression of leukemia in vivo and testing whether interruption of the interaction of Kit and KL can affect the growth of leukemic cells.

Amino Acid Sequence↗
PubMed1995

Expression of mRNA for somatostatin receptor (sstr) types 2 and 5 in individual rat pituitary cells. A double labeling in situ hybridization analysis.

To characterize cell specific expression of sstr subtypes in the pituitary we have analyzed mRNA for sstr1-5 in rat pituitary somatotrophs by reverse transcriptase polymerase chain reaction and determined the pattern and level of expression of mRNA for sstr subtypes 2 and 5 in individual pituitary cell subpopulations by double label in situ hybridization. Purified somatotrophs expressed mRNA for all 5 sstrs. In situ hybridization analysis revealed sstr5 mRNA in 70% of somatotrophs, 57% of thyrotrophs, 38% of corticotrophs, 33% of lactotrophs, and 21% of gonadotrophs. mRNA for sstr2 occurred in 40% of somatotrophs, 36% of thyrotrophs, 26% of lactotrophs, 3% of corticotrophs, and 8% of gonadotrophs. Not only were more cells positive for sstr5 mRNA but the average number of autoradiographic grains/cell was also higher for sstr5 than sstr2. These results show expression of multiple sstr genes in individual pituitary cells. mRNA for sstr2 and 5 occur in each of the 5 major pituitary cell subsets, sstr5 mRNA being more widely and more abundantly expressed than sstr2.

Animals↗
PubMed1995

[Motoneuronal death following prevention of reinnervation during postnatal development].

The hypothesis that survival of motoneurons depends on targets postnatally was tested in Wistar rats of known age. Under ether anesthesia, the cut distal end of a medial gastrocnemius (MG) nerve was anchored to the lateral gastrocnemius (LG) muscle to prevent reinnervation. The compound action potential (CAP) in response to stimulation of the MG nerve was recorded from L4 and L5 ventral roots to evaluate the degree of motoneuronal death in the nerve. CAPs of MG nerves were greatly reduced 1 to 8 months after the operation in the rats operated on at 6 or 9 days of age, which indicates that the majority of MG motoneurons died after the operation. In contrast, the CAPs in the animals which were operated on at older than 12 days were similar to normal animals. However, the number of motor units that remained in the implanted MG nerve was 1.3 on the average in the rats operated on at 12-days-old. In normal rats, it was 87. Thus, the results indicate that in the rats operated on at 12 days of age, a majority of MG motoneurons survived without making functional synapses. We conclude that there is a sharp critical period, between 9 and 12 days after birth, during which motoneuronal target dependency changes.

Animals↗
PubMed1995

Distinct mRNA expression of the highly homologous convertases PC5 and PACE4 in the rat brain and pituitary.

Posttranslational endoproteolysis is essential for the production of biologically active peptides from inactive precursors. Six kexin/substilisin-like endoproteases have been characterized in mammalian species. To understand the complex physiological functions of each convertase within a cellular context it is necessary to comprehensively define its tissue distribution and cohabitation with other members of the family. Previous studies demonstrated the distinct distribution of PC1, PC2, and furin mRNAs in the pituitary and brain, suggesting a unique function for each enzyme. In the present study, the mRNA tissue distributions of the two most recent and homologous members, PC5 and PACE4, were analyzed in rat pituitary and brain using in situ hybridization histochemistry. In the pituitary, the anterior lobe exhibited moderate levels of PC5 and high levels of PACE4 mRNAs. The intermediate lobe showed low levels of PC5 expression, while PACE4 mRNA levels were undetectable. PACE4 transcripts were detected throughout cells of the neural lobe suggesting expression in pituicytes. In the brain, PC5 expression was more restricted than PACE4. PC5 mRNA was detected only in neuronal cells, whereas PACE4 mRNA was expressed in both neuronal and glial cells. In areas that are rich in neuropeptides such as cortex, hippocampus, and hypothalamus, mRNA levels of PC5 were high but PACE4 were low or undetectable. In regions, such as the amygdaloid body and thalamus, distinct but complementary distributions of PC5 and PACE4 mRNAs were observed. The medial habenular and cerebellar Purkinje cells expressed very high levels of PACE4 mRNA. The present data strongly suggest unique tissue-specific functions of PC5 and PACE4.

Animals↗
PubMed1994

Functional dissection of the Autographa california nuclear polyhedrosis virus enhancer element hr5.

The hr5 enhancer element of Autographa californica nuclear polyhedrosis virus stimulates transcription from baculovirus-delayed early promoters in the presence of the viral transactivator, IE1. Gel retardation analyses of interactions between a fragment of hr5 and extracts prepared from cells transfected with an IE1-encoding plasmid revealed the presence of three DNA-protein complexes. In order to better define the functional domains of the hr5 enhancer, we constructed a set of plasmids containing partial deletions in the enhancer element. These constructs were tested for both in vitro DNA binding activity and enhancer function in transient assays. The results indicated that the minimum sequence required for DNA-protein interactions was half of the conserved 24-bp palindrome that is contained within a 60-bp direct repeat (DR60). However, the minimum sequence required for enhancer function was a complete copy of DR60. Template challenge experiments indicated that IE1 bound with equal affinity with a complete or a half copy of DR60. The deletion analyses were confirmed by in vitro binding and transient expression assays with synthetic oligonucleotides.

Animals↗
PubMed1994

Progressive serum IgE elevation in the B6C3F1 mouse following withdrawal of dietary vomitoxin (deoxynivalenol).

Vomitoxin (deoxynivalenol) is a fungal toxin that induces serum IgA hyperelevation, IgA autoantibodies, mesangial IgA deposition in mice upon dietary exposure. The capacity of dietary vomitoxin to similarly alter serum IgE was assessed in female B6C3F1 mice. Ingestion of 25 ppm vomitoxin in AIN-76A semipurified diet resulted in 2.7-, 4-, 5- and 2.3-fold increases in serum IgE relative to controls after 12, 16, 20, and 24 weeks of toxin feeding, respectively. When mice were fed 25 ppm vomitoxin for 8 weeks and continued on toxin-free diet, serum IgE levels were 2.4, 4, 4.9, and 2-fold that of controls at 12, 16, 20, and 24 weeks, respectively. IgE levels were not significantly different between treatment and withdrawal groups at Weeks 12-24. These results differed from those of serum IgA, which increased much earlier and only during toxin administration, and those of IgG, which was largely unaffected compared to controls. The results indicate that a defined period of vomitoxin ingestion can subsequently induce progressive dysregulation of IgE production in addition to previously described IgA-related pathologic effects.

Animals↗
PubMed1994

Elevated gene expression and production of interleukins 2, 4, 5, and 6 during exposure to vomitoxin (deoxynivalenol) and cycloheximide in the EL-4 thymoma.

Aberrant elevation of serum IgA and induction of murine IgA nephropathy following dietary exposure to the naturally occurring trichothecene vomitoxin (VT or deoxynivalenol) may involve dysregulation of cytokine production at the T cell level. EL4.IL-2 (EL-4), a cloned thymoma that produces interleukins (IL)-2, 4, 5, and 6, was used as a T cell model to investigate the in vitro effects of VT on interleukin production and gene expression. When supernatants of cells stimulated with phorbol 12-myristate 13-acetate (PMA) were assessed by enzyme-linked immunosorbent assay, IL-2, 4, and 5 were increased in the presence of 50 and/or 100 ng/ml VT for 2 and/or 8 days of culture. IL-2, 5, and 6 were also significantly elevated in the presence of 10-100 ng/ml of cycloheximide (CHX), another protein synthesis inhibitor, after 8 days of culture. As demonstrated by Northern analysis, VT at the levels between 50 and 100 ng/ml superinduced IL-2, 4, 5, and 6 mRNAs in PMA-stimulated EL-4 cells during a 24 hr culture period. Similar effects in PMA-treated samples were observed for CHX at 50, 100, 250, 1000, and 10000 ng/ml. mRNA levels for both IL-4 and IL-5, but not IL-2 and IL-6, were increased in unstimulated EL-4 cultures exposed to 50 and 100 ng/ml VT for 48 hr when analyzed by reverse transcriptase-polymerase chain reaction. Using [3H]leucine incorporation as a measurement of protein synthesis, IC50s for VT and CHX were estimated to be 280 and 55 ng/ml, respectively. This study indicates that VT as well as CHX could increase production of several interleukins in the EL-4 model even when present at concentrations that partially inhibited protein synthesis, whereas IL mRNA superinduction occurred across a broader range of concentrations that included maximal protein synthesis inhibition.

Clone Cells↗