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Biomedical subjects

E Wang

Publications and source records attributed to E Wang.

At least 235 records · Page 13Linked to original sources
PubMed1995

Fumonisin B1 alters sphingolipid metabolism and disrupts the barrier function of endothelial cells in culture.

Fumonisins are responsible for at least two diseases of veterinary importance (equine leukoencephalomalacia and porcine pulmonary edema) and are carcinogenic for experimental animals and, perhaps, humans. They have been found to disrupt sphingolipid metabolism in many types of cells, including hepatocytes, neurons, and renal cells. In this study, endothelial cells form porcine pulmonary arteries were cultured on micropore filters as a model for the endothelial barrier, and barrier function was quantitated as the movement of albumin across the endothelial monolayers. Fumonisin B1 increased the amount of free sphinganine by 20- to 30-fold within 3 hr, as expected for inhibition of sphinganine (sphingosine) N-acyltransferase by this mycotoxin. At 30 to 50 microM, fumonisin B1 doubled the rate of albumin transfer across endothelial monolayers; however, there was no loss of cell viability based on morphology or trypan blue exclusion. When 15 microM D-erythro-sphinganine was added to the cells, the rate of albumin transfer also doubled (after 24 hr incubation) without a loss of viability; however, this treatment increased the cellular level of sphinganine by > 100-fold. Addition of 25 microM sphinganine caused even greater albumin transfer, but also resulted in significant cell death. These results establish that fumonisin B1 and D-erythro-sphinganine allow accelerated passage of macromolecules across the endothelium. Fumonisin B1 alters sphingolipid biosynthesis with an elevation of sphinganine in the cells which may, at least in part, explain the observed disruption of endothelial barrier function.

Albumins↗
PubMed1995

Autoregulation of Tcr V region epitopes in autoimmune disease.

Normal individuals possess low levels of autoantibodies specific for certain peptide defined regions of T-cell receptor (Tcr) variable regions, particularly CDR1 and Fr3. These regions are predicted to be exposed on the surface of the native molecule and, by analogy and comparison with immunoglobulins, correspond to public idiotype determinants. The anti-Tcr idiotype antibodies appear to be ubiquitous and we propose that they play a role in the regulation of T-cell function. To delineate the parameters of expression of these antibodies, we characterized anti-Tcr antibody activity in normal individuals, in those suffering from the autoimmune diseases rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), and in patients with non-autoimmune arthritis (osteoarthritis) as a disease control. There were significant increases in autoantibody levels in the autoimmune patients. There was also variation in isotype and the particular variable regions recognized. IgM autoantibodies directed against a few peptide defined determinants were elevated in RA, whereas SLE patient sera showed high levels of IgG binding to a broad spectrum of Tcr peptides.

Arthritis, Rheumatoid↗
PubMed1995

Chronic toxicity of fumonisins from Fusarium moniliforme culture material (M-1325) to mink.

Adult female mink (Mustela vison) were fed a diet that contained Fusarium moniliforme culture material that provided dietary concentrations of 89 ppm fumonisin B1, 21 ppm fumonisin B2, and 8 ppm fumonisin B3 for 87 days. During the trial, there was mild lethargy in the mink fed fumonisins, but no other clinical signs or differences in feed consumption (measured during the first two weeks), body weights, or survivability were observed between the fumonisin-treated and control mink. Several hematologic parameters (mean corpuscular hemoglobin concentration, plasma total solids, and lymphocyte concentration) and serum chemical concentrations (globulin, phosphorus, potassium, blood urea nitrogen, creatinine, bilirubin, and cholesterol) and activities (alkaline phosphatase, alanine aminotransferase, amylase, and aspartate aminotransferase) were greater in the mink fed fumonisins than in the controls. Serum albumin/globulin and sodium/potassium ratios and chloride concentrations were lower in the fumonisin-fed mink than in the controls. The concentrations of free sphinganine and the ratio of free sphinganine to free sphingosine in the liver and kidneys of the fumonisin-treated mink were greater than in the control mink. No histopathologic alterations were associated with fumonisin treatment. These results indicate that long-term dietary exposure to F. moniliforme culture material containing 118 ppm total fumonisins is not lethal to adult mink, but can produce adverse physiological effects in the animals.

Animals↗
PubMed1995

Expression of proliferation-specific genes in the mucosa adjacent to colon carcinoma.

BACKGROUND: One of the main concerns in colon carcinoma therapy is local recurrence of the malignancy at the site of resection. Previous studies have shown that morphologically normal-appearing mucosa adjacent to colon carcinoma is different from mucosa distant from carcinoma. Mucosa adjacent to a carcinoma is characterized by crypt lengthening, cell hypertrophy, and change in production of mucopolysaccharides from sulfomucin in normal mucosa to sialomucins in carcinomas and adjacent mucosa. Recently there have been reports suggesting that there is an upward extension of the proliferative compartment in colonic crypts of this adjacent mucosa. METHODS: Immunoblot analysis using antibodies to retinoblastoma, statin, c-Fos, c-Jun, and Cdc-2 proteins was used for our study on the expression of early cell cycle genes in carcinoma and its adjacent mucosa. In all, 15 tissue samples obtained from patients with colon carcinoma were analyzed. Tissue specimens were collected and immediately dissected as tumor, 0 to 1, 1 to 2, 2 to 3, 3 to 4, and 4 to 5 cm from the primary lesion. Dissected pieces were homogenized separately and subjected to immunoblot analysis. RESULTS: We found upregulation of c-Fos, c-Jun, and Cdc-2 expression in carcinoma and adjacent mucosa up to 4 cm from the edge of the carcinoma. The phosphorylated form of retinoblastoma is present in the carcinoma as well as in adjacent mucosa up to 4 cm from the margin of the carcinoma. Furthermore, we observed that the level of statin, a nonproliferation-specific nuclear protein, is very low in the primary lesion and in adjacent mucosa up to 3 cm. CONCLUSIONS: These results indicate that adjacent tissue up to 3 to 4 cm from the carcinoma has elevated levels of expression for cell cycle traverse-associated genes and down-regulation of nonproliferation-specific gene expressions such as statin. This imbalance indicates that within 3 to 4 cm from the edge of the carcinoma, colonic epithelial cells are already abnormal and may be in the hyperproliferative and preneoplastic state, susceptible to further steps leading to eventual malignant transformation.

Carcinoma↗
PubMed1995

Simultaneous determination of guanine, uric acid, hypoxanthine and xanthine in human plasma by reversed-phase high-performance liquid chromatography with amperometric detection.

A reversed-phase high-performance liquid chromatographic method with amperometric detection is described for the separation and quantification of uric acid, guanine, hypoxanthine and xanthine. The isocratic separation of a standard mixture of the compounds was achieved in 5 min on a Spherisorb 5 C18 reversed-phase column, with a mobile phase of NaH2PO4 (300 mmol dm-3, pH 3.0)-methanol-acetonitrile-tetrahydrofuran (97.8 + 0.5 + 1.5 + 0.2). Uric acid, guanine, hypoxanthine and xanthine were completely separated, with detection limits in the range 2-20 pmol per injection. The effect of pH and the composition of the mobile phase on the separation are described. The hydrodynamic voltammograms of these compounds were recorded at a glassy carbon electrode. The linear range of the calibration graph for each compound was: uric acid, 1-5000 mumol dm-3; guanine, 0.5-2000 mumol dm-3; hypoxanthine, 0.1-500 mumol dm-3 and xanthine, 0.5-5000 mumol dm-3. The within- and between-day precision was good. The uric acid and hypoxanthine content in human plasma was measured using the proposed method. Good recoveries of uric acid (97.9-103%), hypoxanthine (98.0-99.2%), guanine (96.0-98.3%) and xanthine (96.0-102%) were obtained from human plasma. The results of electrochemical detection were in good agreement with those of UV detection.

Calibration↗
PubMed1995

Role of dietary sphingolipids and inhibitors of sphingolipid metabolism in cancer and other diseases.

Sphingolipids are found in all eukaryotic and some prokaryotic organisms and participate in the regulation of cell growth, differentiation, and diverse cell functions including cell-cell communication, cell-substratum interactions and intracellular signal transduction. Nonetheless, the field of nutrition has given scant attention to these compounds so that little is known about the following fundamental questions: What is the fate of sphingolipids that are consumed in food? Does consumption of dietary sphingolipids affect the behavior of cells in the gastrointestinal tract or other organs? How do other factors in the diet affect sphingolipid metabolism? Several recent findings underscore the importance of these questions, for examples: 1) Sphingolipids are digested throughout the GI tract to ceramide and sphingosine, which are highly bioactive compounds that affect cellular regulatory pathways; 2) addition of sphingomyelin to a standard AIN diet (which is essentially devoid of sphingolipids) reduces the appearance of aberrant colonic crypts, and perhaps the number of tumors, in mice treated with a colon carcinogen; and 3) an enzyme of sphingolipid metabolism has been discovered to be the target of a class of toxic and carcinogenic mycotoxins called fumonisins. Given these recent findings, it is possible that some of the confusion that has arisen regarding the relationships between dietary fat and disease might be due to the lack of consideration of the sphingolipids that are also present.

Animals↗
PubMed1995

Characteristics of Rhizobium tianshanense sp. nov., a moderately and slowly growing root nodule bacterium isolated from an arid saline environment in Xinjiang, People's Republic of China.

We performed a numerical analysis of 148 phenotypic characteristics of 20 strains of root nodule bacteria isolated from an arid saline desert soil in the Xinjiang region of northwestern People's Republic of China and compared these organisms with 28 Rhizobium and Bradyrhizobium strains obtained from different regions of the People's Republic of China and from other countries, including nine type strains of different species. All of the strains examined clustered into two groups at a similarity level of more than 63%. Group I included all of the previously described Rhizobium species and was divided into eight subgroups, which corresponded to previously described Rhizobium species, at a similarity level of more than 82%. Group II was divided into the following three subgroups at a similarity level of more than 80% Bradyrhizobium japonicum, a cluster containing 17 moderately and slowly growing strains isolated in the Xinjiang region, and a small subgroup containing three fast-growing strains. The generation times of the moderately and slowly growing strains were 5 to 15 h, and these organisms produced acid in medium containing mannitol. The DNA G+C contents of the members of this group ranged from 59 to 63 mol%. DNA-DNA hybridization experiments revealed that the levels of DNA homology among all of the moderately and slowly growing strains obtained from Xinjiang were more than 70% and that the levels of DNA homology between representative strains of this group and the type strains of all previously described species of root- and stem-nodulating bacteria were low.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Composition↗
PubMed1995

Phylogenetic evidence for the transfer of Pseudomonas cocovenenans (van Damme et al. 1960) to the genus Burkholderia as Burkholderia cocovenenans (van Damme et al. 1960) comb. nov.

Pseudomonas cocovenenans, the producer of bongkrekic acid and toxoflavin, has been described previously by us (N.-X. Zhao, M.-S. Ma, Y.-P. Zhang, and D.-C. Xu, Int. J. Syst. Bacteriol. 40:452-455, 1990) in terms of more than 180 phenotypic traits, G+C content, and DNA relatedness. The bacterium conformed to section II of the genus Pseudomonas. Here, its partial 16S rRNA gene sequence was compared with those of Burkholderia spp., and the results verified that P. cocovenenans is a Burkholderia species. On the basis of the phenotype and genetic characteristics, P. cocovenenans is transferred to the genus Burkholderia as Burkholderia cocovenenans comb. nov.

Amino Acids↗
PubMed1995

Comparison of the genomes of the wild-type French viscerotropic strain of yellow fever virus with its vaccine derivative French neurotropic vaccine.

The French neurotropic vaccine, or FNV, was used extensively in Africa to control yellow fever (YF). Although efficacious, the vaccine caused an unacceptable rate of post-vaccinal complications in children and was subsequently replaced by the 17D vaccine. Here we report that the genomes of the wild-type YF virus French viscerotropic virus and its attenuated vaccine derivative, FNV virus from the Institut Pasteur, Paris, (FNV-IP) differ by 77 nucleotides encoding 35 amino acid substitutions. Comparison of FNV-IP and three other isolates of FNV with other YF vaccine strains (17D-204 and 17DD derived from wild-type strain Asibi) revealed that during the two attenuation processes two common nucleotide changes arose that encode two amino acid substitutions: one is in the membrane protein at amino acid 35 (M-35), the other in non-structural (NS) protein 4B at NS4B-95. These common substitutions may be important in the process of attenuation of viscerotropic disease for humans and monkeys, and/or may be involved in loss of mosquito competence of the vaccine viruses.

Amino Acids↗
PubMed1995

Sequences flanking the pentanucleotide T-antigen binding sites in the polyomavirus core origin help determine selectivity of DNA replication.

Replication of the genomes of the polyomaviruses requires two virus-specified elements, the cis-acting origin of DNA replication, with its auxiliary DNA elements, and the trans-acting viral large tumor antigen (T antigen). Appropriate interactions between them initiate the assembly of a replication complex which, together with cellular proteins, is responsible for primer synthesis and DNA chain elongation. The organization of cis-acting elements within the origins of the polyomaviruses which replicate in mammalian cells is conserved; however, these origins are sufficiently distinct that the T antigen of one virus may function inefficiently or not at all to initiate replication at the origin of another virus. We have studied the basis for such replication selectivity between the murine polyomavirus T antigen and the primate lymphotropic polyomavirus origin. The murine polyomavirus T antigen is capable of carrying out the early steps of the assembly of an initiation complex at the lymphotropic papovavirus origin, including binding to and deformation of origin sequences in vitro. However, the T antigen inefficiently unwinds the origin, and unwinding is influenced by sequences flanking the T antigen pentanucleotide binding sites on the late side of the viral core origin. These same sequences contribute to the replication selectivity observed in vivo and in vitro, suggesting that the inefficient unwinding is the cause of the replication defect. These observations suggest a mechanism by which origins of DNA replication can evolve replication selectivity and by which the function of diverse cellular origins might be temporally activated during the S phase of the eukaryotic cell cycle.

Animals↗
PubMed1995

Cellular patterns of insulin-like growth factor system gene expression in murine chondrogenesis and osteogenesis.

In situ hybridization histochemistry was used to map cellular patterns of gene expression for the insulin-like growth factor (IGF) system in developing murine skeleton from embryonic day 15 (E15) through postnatal day 25 (P25). IGF-I receptor and IGF-II receptor messenger RNAs (mRNAs) are both selectively concentrated in developing chondrocytes and osteoblasts. IGF-II and IGF-binding protein-5 and -6(IGFBP-5 and -6) mRNAs are abundant in mesenchymal condensations and chondroblasts on E15. Chondrocyte IGF-II mRNA levels remain high, but IGFBP-5 and -6 mRNAs decline significantly as cartilage matures. Low levels of IGFBP-6 mRNA are detected in postnatal chondrocytes up to at least P25, but IGFBP-5 mRNA is no longer detected in chondrocytes after E18. IGF-I and IGFBP-2, -3, and -4 mRNAs are detected in surrounding mesenchymal tissue, but are not detected in mesenchymal condensations or chondrocytes at any stage of development. IGFBP-3 mRNA is localized in sprouting capillaries invading the perichondrium and periosteum throughout development. IGF-I, IGF-II, and IGFBP-2, -4, -5, and -6 mRNAs are detected in osteoblasts localized in zones of endochondral ossification from E18 to at least P25. IGFBP-1 mRNA is not detected in cartilage or bone cells at any stage of development. These data confirm the recent report by Shinar et al. that IGF-II, but not IGF-I, mRNA is detected in rat chondrocytes in vivo and show that this pattern also applies to the mouse. The present study demonstrates, for the first time, the cell-specific patterns of IGF-I and -II receptor and IGFBP-2 to -6 gene expression during the processes of chondro- and osteogenesis in vivo. Interestingly, IGF-II, both IGF receptors, and IGFBP-5 and -6 are simultaneously coexpressed in chondrocyte precursors early in skeletal development, suggesting functional interactions between these specific factors in chondrogenesis. Both IGFs, both IGF receptors, and IGFBP-2, -4, -5, and -6 are all expressed in osteoblasts, providing evidence for potential local interactions between these IGF system components in osteogenesis. Thus, 9 of 10 known components of the IGF system demonstrate dynamic cell-specific patterns of gene expression during chondro- and osteogenesis, supporting the view that the IGF system has a complex and integral role within the developing skeleton.

Animals↗
PubMed1995

Angiotensinogen synthesis in the liver is independent of physiological estrogen levels.

We determined the physiological importance of endogenous estrogen in the regulation of angiotensinogen synthesis in the liver. The plasma levels of angiotensinogen and hepatic levels of angiotensinogen mRNA were studied in the rat in comparison to those of T-kininogen, a plasma protein whose synthesis in the liver is primarily estrogen-dependent. Plasma levels of T-kininogen and hepatic levels of T-kininogen mRNA were 3- and 2-fold higher in adult females, respectively, than in adult males, whereas there were no sex differences in levels of either plasma angiotensinogen or hepatic angiotensinogen mRNA. Ovariectomy in female rats abolished the sex differences in the levels of plasma T-kininogen and hepatic T-kininogen mRNA, but it did not affect those of plasma angiotensinogen and hepatic angiotensinogen mRNA. These results suggest that, in contrast to T-kininogen, angiotensinogen synthesis in the liver is unlikely to be controlled by endogenous levels of estrogen.

Aging↗
PubMed1995

Fluoresein diacetate uptake to determine the viability of human fetal cerebral cortical cells.

We investigated the accuracy of fluorescein diacetate uptake as an indicator of the viability of human fetal cerebral cortical cells. Cortical cells from 16-26-week-old normal fetuses were studied. The cortices were dissociated mechanically with normal saline to make a suspension. Fluorescein diacetate uptake and trypan blue exclusion were compared as methods for examining cell viability. Our results show that fluorescein diacetate uptake is a simple and sensitive method for examining human fetal cortical cell viability.

Cell Survival↗
PubMed1995

Characterization of the tissue regression process in the uterus of older mice as apoptotic by the presence of Tp30, an isoform of terminin.

Whether old uteri that have undergone involution do so by an apoptotic mechanism was examined by the presence of known biochemical and morphological markers for programmed cell death. Terminin, a protein identified by an unique monoclonal antibody, has three forms, Tp-90, Tp-60, and Tp-30: Tp-90 (the 90 kDa form) is only present in growing and quiescent non-growing cells; Tp-60 (the 60 kDa form) is found in senescent cells; and finally, Tp-30 (the 30 kDa form) is found in cells committed to apoptotic death. Biochemical analysis of a protein, Tp30, previously identified as a marker for the commitment to programmed cell death, was performed with both young (5-month-old) and old (24-month-old) C57BL/6J mouse uteri. In addition to biochemical analysis of Tp30 presence in uterine tissue, propidium iodide (PI) staining and DNA framentation by nick-end labelling with fluorescence-conjugated UTP were used to characterize apoptosis-related changes in the chromatin organization of the nucleus. Results indicate that within the old uterus Tp-30 is indeed detected in the tissue extracts and was the major terminin band, while Tp-90 and Tp-60 were the major bands observed in extracts of the younger mouse uterus. The presence of Tp30 in the older uterine tissue suggests that the tissue regression which has occurred in the uterus of older mice may be apoptotic in nature. This suggestion is further supported by the demonstration of increases in the number of cells showing apoptotic morphology, i.e. positive staining with UTP reflecting the presence of nuclei with nicked DNA, localized exclusively in the uterine stroma of older females. The presence of DNA fragmentation, as reflected by UTP staining, was virtually absent from the young uteri. These data suggest that apoptosis may be a part of the cellular mechanism contributing to the regression of uterine tissue in the older female during involution, appearing as an age-dependent event.

Aging↗
PubMed1995

Preliminary study on controlled hypotension induced by nimodipine in craniocerebral surgery.

Nimodipine, produced in China, was applied to lower the blood pressure (BP) in 20 cases in craniocerebral operation. 0.02% solution of Nimodipine was dripped intravenously (by 0.02% of density), at a preliminary speed of 600-800 micrograms/min, and 4-12 mg of total dose. Mean arterial pressure (MAP) decreased and maintained at 7.3-8.0 kPa, and lasted 30-60 minutes. The scopes of decreasing pressure were 33.0%-37.7% of MAP, 31.6%-35.6% of systolic pressure (SP), and 36.1%-41.9% of diastolic pressure (DP). The results of lowering pressure which reduced the intraoperative bleeding were significant. After withdrawal of drug supply for 15-30 minutes, the BP raised up to the normal level. No "rebounding BP rise" occurred.

Adolescent↗