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Biomedical subjects

E Wang

Publications and source records attributed to E Wang.

At least 199 records · Page 11Linked to original sources
PubMed1997

Body composition and endocrine function in women with acquired immunodeficiency syndrome wasting.

The acquired immunodeficiency syndrome (AIDS) wasting syndrome is a devastating complication of human immunodeficiency virus (HIV) infection characterized by progressive weight loss and severe inanition. In men, the wasting syndrome is characterized by a disproportionate decrease in lean body mass and relative fat sparing. In contrast, relatively little is known about the gender-specific changes in body composition that characterize AIDS wasting in women. Three groups of women were studied to determine body composition and hormonal changes with respect to stage of wasting [nonwasting (NW; weight >90% ideal body weight; weight loss <10% of preillness maximum; n = 12), early wasting (EW; weight >90% ideal body weight; weight loss >10% of preillness maximum; n = 10), and late wasting (LW; weight <90%; n = 9)] and compared with a control group of 12, healthy, age-matched women. Weight loss averaged 6 +/- 6% (NW), 15 +/- 6% (EW), and 20 +/- 8% (LW) in the three groups. Lean, fat, and muscle masses were determined by dual energy x-ray absorptiometry and urinary creatinine excretion. Subjects were 36 +/- 5 yr of age (mean +/- SD) with a CD4 cell count of 379 +/- 239 cells/mm3. The body mass index was 24.4 +/- 2.6 kg/m2 (NW), 22.2 +/- 1.2 kg/m2 (EW), 18.2 +/- 2.0 kg/m2 (LW), and 24.3 +/- 2.6 kg/m2 (controls; P < 0.01, NW vs. EW; P < 0.0001, NW vs. LW). Lean body mass indexed for height was 15.7 +/- 2.4 kg/m2 (NW), 14.8 +/- 2.0 kg/m2 (EW), and 13.7 +/- 1.2 kg/m2 (LW) and was decreased significantly only in the LW group (P < 0.05 vs. NW). Muscle mass was 96% (NW), 94% (EW), and 78% (LW) of that predicted for height (P < 0.05, NW vs. LW). In contrast, fat mass indexed for height was decreased significantly among patients in both the EW and LW groups [8.7 +/- 1.9 kg/m2 (NW), 6.5 +/- 1.9 kg/m2 (EW), and 3.7 +/- 1.4 kg/m2 (LW); P < 0.05, NW vs. EW; P < 0.001, NW vs. LW). Expressed as a percentage of the value in nonwasting HIV-positive controls (NW), the relative loss of fat was greater than the loss of lean mass with progressive degrees of wasting [EW, 25% vs. 6% (fat vs. lean); LW, 58% vs. 13%]. The prevalence of amenorrhea was 20% among study subjects [17% (NW), 10% (EW), and 38% (LW)]. The percent predicted muscle mass was significantly lower in subjects with amenorrhea (74 +/- 8%) compared to that in eumenorrheic HIV-positive subjects (94 +/- 4%; P < 0.05). Estradiol levels were lower among subjects with amenorrhea (17.6 +/- 21.8 pg/mL) compared to eumenorrheic HIV-positive (48.9 +/- 33.6 pg/mL) and control (68.3 +/- 47.6 pg/mL) subjects and did not correlate with body composition. Mean free testosterone, but not total testosterone, levels were decreased in subjects with EW and LW compared to those in age-matched healthy controls, but not compared with those in NW [0.9 +/- 0.6 ng/dL (NW), 0.7 +/- 0.4 ng/dL (EW), 0.6 +/- 0.3 ng/dL (LW), and 2.0 +/- 2.4 ng/dL (controls); P < 0.05, EW vs. controls and LW vs. controls] and correlated with muscle mass (r = 0.37; P < 0.05). The percentages of women with free testosterone levels below the age-adjusted normal range were 33% (NW), 50% (EW), and 66% (LW). Dehydroepiandrosterone sulfate levels were also low in the subjects with LW compared to those in the control group [98 +/- 85 microg/dL (NW), 102 +/- 53 microg/dL (EW), 55 +/- 46 microg/dL (LW), and 132 +/- 68 microg/dL (controls); P < 0.05 LW vs. controls] and were correlated highly with free testosterone levels (r = 0.73; P < 0.00001) and also with muscle mass (r = 0.48; P < 0.01). These data demonstrate that women lose significant lean body and muscle mass in the late stages of wasting. However, in contrast to men, women exhibit a progressive and disproportionate decrease in body fat relative to lean body mass at all stages of wasting, consistent with gender-specific effects in body composition in AIDS wasting. (ABSTRACT TRUNCATED)

Absorptiometry, Photon↗
PubMed1997

Activin A and follistatin are dynamically regulated during human pregnancy.

Activin A (beta A-beta A) and activin B (beta B-beta B) are related dimeric proteins that regulate numerous cellular activities. Activin activity is bioneutralized by follistatin, a specific and high-affinity binding protein. Recently, our group developed specific and sensitive enzyme-linked immunosorbent activin assays that do not detect either activin isoform when bound to follistatin, therefore, the assays are specific for biologically relevant ligands. Activin A is measurable in the serum of pregnant women (cross-sectional sample collection), while activin B is not detected in maternal serum. However, activin B is measurable in amniotic fluid and cord blood sera. The purpose of this study was to measure serum activin A, activin B, and follistatin prospectively in longitudinally collected samples during pregnancy. This study design offered observations of relative changes in serum hormone concentration with each person serving as an internal reference. Serum samples were collected bimonthly from seven pregnant women beginning within the second month of gestation, and up to, but not including, the onset of labor. Six of the seven women had normal labor and delivery. One patient required pitocin (an oxytocin agonist) for induction of labor which led to delivery. Activin A, activin B, total follistatin, free follistatin, human chorionic gonadotropin, estradiol, progesterone, FSH, and LH were measured in maternal serum samples using specific assays. Serum activin A levels increased in the final month of pregnancy in the six patients who delivered following normal labor (< 0.78 ng/ml (first trimester) to 1-6 ng/ml (term)). Activin B was not detected in any serum sample (< 0.78 pg/ml). Total serum follistatin (free follistatin, follistatin-activin, and follistatin-inhibin) increased 10- to 45-fold in the final month of pregnancy in four of the women undergoing normal labor (10 ng/ml (first trimester) to 100-450 ng/ml (final month)). Total follistatin was high and variable in two women throughout pregnancy. Total follistatin returned to basal serum concentration in three of the patients during the last 2 weeks of pregnancy. Free follistatin was detected throughout pregnancy (range < 2-35 ng/ml). Free follistatin represented a small percentage of the total follistatin throughout the time of pregnancy and did not rise coincident with the rise in total follistatin. Serum activin A and activin B were not detected during the entire course of pregnancy in the one patient who did not have normal labor and total follistatin did not rise in the last trimester of pregnancy. Gonadotropin and steroid hormones were measured in all patients and were within normative ranges for human pregnancy (inclusive of the non-laboring patient). The results suggest that immunodetectable activin A is present in the third trimester of pregnant women who have normal onset labor. The total follistatin assay results suggest that follistatin-activin (or -inhibin) complexes are upregulated during the third trimester of pregnancy. Importantly, activin A production exceeds the binding capacity of circulating follistatin. Because binding protein free activin A is biologically active we conclude that the activin A detected in late pregnancy is biologically relevant. The findings are consistent with our hypothesis that activin A is an endocrine factor during the last trimester of human pregnancy and may be involved in normal labor.

Activins↗
PubMed1996

Genetic variation in yellow fever virus: duplication in the 3' noncoding region of strains from Africa.

The nucleotide sequences of three regions of the genomes of 13 yellow fever (YF) virus isolates were determined to define genetic variation and evolution of the virus. Phylogenetic trees generated from sequences of either the 5' terminal 1320 nucleotides of the genome, 754 nucleotides from the NS4A and NS4B genes, or the 3' terminal 511 nucleotides were very similar and contained minor differences. Overall, these results suggested that there were at least four major genotypes of YF virus, including one in Central/East Africa, one in West Africa, and two in South America. Examination of the 3' noncoding region (3'NCR) showed that only West African strains had a 3'NCR of 511 nucleotides while strains from Central/East Africa and South America had shorter 3'NCRs (443-469 nucleotides) due to the absence of YF specific repeat sequences (RYFs). Central/East African strains have two RYFs and West African strains have three RYFs while South American strains only have one copy of the RYF. It is speculated that duplication of the RYF took place in West Africa subsequent to the presumed introduction of YF virus into South America. Thus, both tick-borne (Mandl et al., J. Virol. 65, 4070-4077, 1991 and Wallner et al., Virology 213, 169-178, 1995) and mosquito-borne flaviviruses have variable 3'NCRs.

Africa↗
PubMed1996

There is substantial agreement among interspecies estimates of DNA repair activity.

Faithful maintenance of the genetic material is essential for cellular and organismal function. Thus the activity with which nuclear and mitochondrial DNA is repaired in somatic cells is likely to be an crucial determinant of maximal lifespan (MLS). However there has been controversy over both the actual rates of DNA repair in a variety of species, and the correlation of those rates with maximal lifespan. Five comparative studies of DNA repair have been re-analyzed with reference to an internal repair standard. Although some variance in measurements of DNA repair activity of the same species in different laboratories was observed, overall there is good agreement on the rank order of repair activity once those studies are internally calibrated. A six-fold range of relative DNA repair activity was observed, with mouse, rat and shrew lowest (0.9 to 1.0), and human and gorilla highest (4.5 to 5.3). The correlation between DNA repair activity and MLS was good, but not excellent (r2 = 0.845); a possible explanation is that active DNA repair is a necessary but not sufficient condition for long MLS. We investigated the kinetics of mitochondrial mutagenesis and tumorigenesis in mice and humans, and observed that each proceeds at a rate approximately 40-fold faster in mice than in humans. Thus one likely consequence of the deficiency of DNA repair in small rodents is an increased rate of mutagenesis and tumorigenesis. The large differences in metabolic investment in genomic maintenance in mice versus humans is a prediction of the disposable soma theory of aging, which is discussed.

Aging↗
PubMed1996

Ionophore 4-BrA23187 transports Zn2+ and Mn2+ with high selectivity over Ca2+.

The cation transport selectivities of the Ca2+ ionophores A23187, Ionomycin, and 4-BrA23187 have been determined using a model system comprised of phospholipid vesicles loaded with the chelator/indicator Quin-2. At pH 7.00 and a 100 microM concentration of the cations, A23187 displays the transport selectivity sequence Zn2+ > Mn2+ > Ca2+ > Co2+ > Ni2+ > Sr2+, with the absolute rates of transport spanning approximately 3 orders of magnitude. Similar data are obtained with Ionomycin, although the relative transport rates of Zn2+ and Mn2+ are equivalent, and the range of absolute rates is decreased by a factor of approximately 3. When values are normalized to those of Ca2+, transport selectivity is seen to be only weakly related to complexation or extraction selectivity. It is also seen that, when used to manipulate Ca2+ (or Mg2+), both ionophores can be expected to alter the distribution of additional divalent cations which have known biological activities. 4-BrA23187 is a low-activity ionophore for Ca2+, compared to A23187 and Ionomycin, while retaining comparable activities as an ionophore for the other cations. As a consequence, 4-BrA23187 is highly selective for the transport of Zn2+ and Mn2+, compared to Ca2+, with selectivity ratios approaching that of valinomycin for K+ over Na+ when conditions are optimal. Plots of the log of the rate of cation transport vs the log of the ionophore concentration indicate that Ca2+ is transported primarily as a 2:1 complex by A23187 and 4-BrA23187, but Zn2+ and Mn2+ are transported, in part, as 1:1 complexes. These findings, together with a postulated low stability of 2:1, compared to 1:1 complexes between 4-BrA23187 and divalent cations, partially explain the novel transport selectivity of this compound. Unlike A23187 or Ionomycin, 4-BrA23187 may be useful for investigating cell regulation by Zn2+ and Mn2+, without interference by regulatory mechanisms which respond to Ca2+.

Aminoquinolines↗
PubMed1996

Bcl-2 potentiates the maximal calcium uptake capacity of neural cell mitochondria.

Expression of the human protooncogene bcl-2 protects neural cells from death induced by many forms of stress, including conditions that greatly elevate intracellular Ca2+. Considering that Bcl-2 is partially localized to mitochondrial membranes and that excessive mitochondrial Ca2+ uptake can impair electron transport and oxidative phosphorylation, the present study tested the hypothesis that mitochondria from Bcl-2-expressing cells have a higher capacity for energy-dependent Ca2+ uptake and a greater resistance to Ca(2+)-induced respiratory injury than mitochondria from cells that do not express this protein. The overexpression of bcl-2 enhanced the mitochondrial Ca2+ uptake capacity using either digitonin-permeabilized GT1-7 neural cells or isolated GT1-7 mitochondria by 1.7 and 3.9 fold, respectively, when glutamate and malate were used as respiratory substrates. This difference was less apparent when respiration was driven by the oxidation of succinate in the presence of the respiratory complex I inhibitor rotenone. Mitochondria from Bcl-2 expressors were also much more resistant to inhibition of NADH-dependent respiration caused by sequestration of large Ca2+ loads. The enhanced ability of mitochondria within Bcl-2-expressing cells to sequester large quantities of Ca2+ without undergoing profound respiratory impairment provides a plausible mechanism by which Bcl-2 inhibits certain forms of delayed cell death, including neuronal death associated with ischemia and excitotoxicity.

Apoptosis↗
PubMed1996

(i, i + 4) Ion pairs stabilize helical peptides derived from smooth muscle caldesmon.

The central region of smooth muscle caldesmon contains 10 repeats of a 13-amino-acid residue motif that is rich in charged side chains. This region has been predicted to have a strong alpha-helical propensity, and the helical structure was thought to be stabilized by the interactions between oppositely charged side chains of residues at positions i and i + 4 (Wang, C.-L. A., Chalovich, J.M., Graceffa, P., Lu, R.C., Mabuchi, K, and Stafford, W.F., J.Biol. Chem. 266, 13958-13963, 1991). Two synthetic peptides corresponding to these repeats, each containing 25 and 60 amino acid residues, indeed assume an alpha-helical conformation that is stable over a wide range of salt concentration and pH, and exhibit a typical helix-coil transition upon heating. Most significantly, when the amino acid sequence of the 25-mer is randomized without losing the i-to-i + 4 ion pairs, the peptide maintains a helical content comparable to that of the wild-type peptide, whereas another peptide variant with a sequence rearranged to eliminate all i-to-(i + 4) ion pairs has much less helicity, suggesting that specific interactions between residues with (i,i + 4) spacings are important determinants for the maintenance of secondary structure in this region of caldesmon.

Amino Acid Sequence↗
PubMed1996

Solution structure of a pyrimidine-purine-pyrimidine triplex containing the sequence-specific intercalating non-natural base D3.

We have used NMR spectroscopy to study a pyrimidine-purine-pyrimidine DNA triplex containing a non-natural base, 1-(2-deoxy-beta-D-ribofuranosyl)-4-(3-benzamido)phenylimidazole (D3), in the third strand. The D3 base has been previously shown to specifically recognize T-A and C-G base-pairs via intercalation on the 3' side (with respect to the purine strand) of the target base pair, instead of forming sequence-specific hydrogen bonds. 1H resonance assignments have been made for the D3 base and most of the non-loop portion of the triplex. The solution structure of the triplex was calculated using restrained molecular dynamics and complete relaxation matrix refinement. The duplex portion of the triplex has an over-all helical structure that is more similar to B-DNA than to A-DNA. The three aromatic rings of the D3 base stack on the bases of all three strands and mimic a triplet. The conformation of the D3 base and its sequence specificity are discussed.

Base Sequence↗
PubMed1996

Characterization of senescence- and apoptosis-dependent forms of terminin as derived from a precursor found in replicating and nonreplicating cells.

Previously we have reported the production of a monoclonal antibody (Mab 1.2) which recognizes a cytoplasmic protein, terminin, in three different molecular weights: 90 (Tp90), 60 (Tp60), and 30 kDa (Tp30) forms. Further characterization shows that Tp90 is found in young growing and nongrowing quiescent fibroblasts, while Tp60 is found in permanently growth-arrested senescent fibroblasts and Tp30 in cells committed to undergo programmed cell death (apoptosis). In tissue, Tp90 is found in embryonic brain; later, in neonatal brain after terminal differentiation is completed, only Tp60 is found. Tp30 is found in crude liver fractions extracted without the protective action of protease inhibitors. In all these circumstances, Tp90 is mostly seen in the detergent-soluble fraction, while Tp60 and Tp30 are detergent-insoluble. We now report that in cultured fibroblasts, as well as in tissues such as brain and liver, Tp60 and Tp30 are derived from the Tp90 polypeptide, indicated by the fact that only the Tp90 species is identified by both immunoblotting and immunoprecipitation assays, when the cell or tissue extracts are prepared in the presence of protease inhibitors. Further evidence shows that immunoprecipitation of in vitro translation products from brain, liver, and cultured fibroblasts also present a single band of Tp90 polypeptide. Pulse-chase experiments show that during apoptosis, Tp90 is processed to Tp60, and eventually to Tp30. However, when the total protein extracts are fractionated, only Tp90 is found in the detergent-soluble fraction, with diminishing quantities during the time course of apoptosis, and Tp30, in contrast, is found as the only protein species in the insoluble fraction, with increasing quantity during the same time course. Newly processed Tp60 is not found in either of the fractions, reflecting its loss during the fractionation procedure. Limited one-dimensional peptide mapping of Tp90 yields three different bands at 30, 28, and 25 kDa, but only the one at 30 kDa is recognized by Mab 1.2. These results lead us to suggest that terminin protein is synthesized in the Tp90 form, and cleaved to lower molecular weight forms depends upon different physiologic conditions, with Tp60 processed in the terminally differentiated or senescent state and rapidly to Tp30 in apoptosis. Our findings further suggest that Tp90's processing to either Tp60 or Tp30 produces insoluble protein forms. Furthermore, the presence of Tp90 in nonapoptotic (either replicating or nonreplicating) cells may reflect the absence of necessary proteolytic action required for the execution of apoptosis. Future experiments will allow us to determine the nature of this proteolytic action, as well as whether this action is due to the autocatalytic action of Tp90 or by other endogenous proteases, and then to determine the significance of this biochemical action in cells.

3T3 Cells↗
PubMed1996

Evidence for disruption of sphingolipid metabolism as a contributing factor in the toxicity and carcinogenicity of fumonisins.

Fumonisins are inhibitors of the biosynthesis of sphingosine and more complex sphingolipids. In eucaryotic cells, fumonisin inhibition of sphingolipid biosynthesis is a result of inhibition of the enzyme ceramide synthase. Large increase in free sphinganine concentration in plant and animal cells are observed within a few hours after exposure to fumonisins and/or Alternaria toxins (AAL-toxins). Some of the sphinganine is metabolized to other bioactive intermediates, and some is released from cells. In animals, free sphinganine accumulates in tissues and quickly appears in blood and urine. Free sphingoid bases are toxic to most cells, and complex sphingolipids are essential for normal cell growth. Fumonisin B1 stimulates sphinganine-dependent DNA synthesis in Swiss 3T3 cells, but is mitoinhibitory in other cell types. In cultured cells the accumulation of bioactive long-chain sphingoid bases and depletion of complex sphingolipids are clearly contributing factors in growth inhibition, increased cell death, and (in Swiss 3T3 cells) mitogenicity of fumonisins. While disruption of sphingolipid metabolism directly affects cells, it may indirectly affect some tissues. For example, fumonisin B1 impairs the barrier function of endothelial cells in vitro. Adverse effects on endothelial cells could indirectly contribute to the neurotoxicity and pulmonary edema caused by fumonisins. It is hypothesized that fumonisin-induced changes in the sphingolipid composition of target tissues could directly or indirectly contribute to all Fusarium moniliforme-associated diseases.

Alternaria↗
PubMed1996

Fumonisin toxicity and sphingolipid biosynthesis.

Fumonisins are inhibitors of sphinganine (sphingosine) N-acyltransferase (ceramide synthase) in vitro, and exhibit competitive-type inhibition with respect to both substrates of this enzyme (sphinganine and fatty acyl-CoA). Removal of the tricarballylic acids from fumonisin B1 reduces the potency by at least 10 fold; and fumonisin A1 (which is acetylated on the amino group) is essentially inactive. Studies with diverse types of cells (hepatocytes, neurons, kidney cells, fibroblasts, macrophages, and plant cells) have established that fumonisin B1 not only blocks the biosynthesis of complex sphingolipids; but also, causes sphinganine to accumulate. Some of the sphinganine is metabolized to the 1-phosphate and degraded to hexadecanal and ethanolamine phosphate, which is incorporated into phosphatidylethanolamine. Sphinganine is also released from cells and, because it appears in blood and urine, can be used as a biomarker for exposure. The accumulation of these bioactive compounds, as well as the depletion of complex sphingolipids, may account for the toxicity, and perhaps the carcinogenicity, of fumonisins.

Amidohydrolases↗
PubMed1996

The effect of fumonisin B1 on developing chick embryos: correlation between de novo sphingolipid biosynthesis and gross morphological changes.

Fumonisins, mycotoxins produced by Fusarium moniliforme and a number of other fungi, are potent inhibitors of the sphinganine-N-acyltransferase, a key enzyme of sphingolipid biosynthesis, and cause neuronal degeneration, liver and renal toxicity, cancer and other injury to animals. In this study we investigated the effect of fumonisin B1 on the sphingolipids of developing chick embryos. After yolk sac injection of fumonisin B1 a concentration and time dependent increase of the sphinganine-over-sphingosine ratio of the embryos could be demonstrated. Studies were done to evaluate the effect of fumonisin B1 on the glycophingolipid pattern of the chick embryos. In the presence of 72 micrograms fumonisin B1 per egg the incorporation of [14C]galactose and of [14C]serine into embryonic glycosphingolipids was reduced by about 70%, although the mass of glycosphingolipids was not affected by the toxin. However, a reduction of the wet weight of the treated embryos was observed. Additionally, histological examinations of whole embryo sections of control and fumonisin B1 treated embryos are presented. Fumonisin B1 caused haemorrhages under the skin as well as in the liver of treated embryos. A close correlation between disruption of sphingoid metabolism and light microscopic detectable tissue lesions could be observed.

Animals↗
PubMed1996

Immunohistochemical analysis of statin in colorectal adenocarcinoma, polyps, and normal mucosa.

PURPOSE: The search for an understanding of the kinetics of the malignant cell is an ongoing focus of research. The aim of the present study was to determine whether there were any differences in the expression of statin, a nonproliferation-specific nuclear protein, among different colorectal tissues and whether there is any relationship between statin presence and neoplastic aggressivity. METHODS: The study population consisted of specimens from 19 patients who underwent resection for carcinoma, one for villous adenoma, and seven for colonoscopic polypectomies. Tissue samples were taken from the center of the specimen and from mucosa 10 cm from the lesion. RESULTS: Statin immunoreactivity was evaluated by counting stained nuclei in ten randomly chosen fields, and percent of positive cells was calculated. Average percentage of statin-positive cells was 34.33 +/- 6.81 in the normal crypt, 44.42 +/- 7.28 for polyps, and 7.74 +/- 5.67 for carcinomas (significantly lower than normal mucosa and polyps; P < 0.001). CONCLUSION: Statin expression is dramatically diminished in invasive carcinoma tissue, but it did not help determine aggressivity with respect to Dukes stage.

Adenocarcinoma↗
PubMed1996

Interferon gamma (IFNgamma) gene transfer of an EMT6 tumor that is poorly responsive to IFNgamma stimulation: increase in tumor immunogenicity is accompanied by induction of a mouse class II transactivator and class II MHC.

Abstract Interferon gamma (IFNgamma) is an important cytokine with immunomodulatory properties that include activation of immune cells and induction of class I and class II major histocompatibility complex antigens. In this study a retroviral vector was used to introduce the IFNgamma gene into EMT6 tumor cells to assess the effect of IFNgamma gene expression on tumor immunogenicity. Transfectants were selected in G418-containing tissue-culture medium and were determined to express the inserted IFNgamma gene by reverse transcriptase/polymerase chain reaction. Flow-cytometric analysis revealed that parental unmodified EMT6 cells constitutively expressed only class I MHC and were poorly responsive to exogenous IFNgamma stimulation, whereas class II MHC was induced in IFNgamma-transfected cells. The induction of class II MHC in IFNgamma-transfected cells correlated with the expression of a mouse class II transactivator gene that was dormant in unmodified or mock-transfected cells. In addition, IFNgamma-gene-transfected tumor cells were found to secrete up to 17 ng IFN (equivalent to 75 units/10(6) cells) by enzyme-linked immunosorbent assay (ELISA). Whereas parental EMT6 cells grew unchecked, the growth of genetically modified tumor cells was significantly inhibited in immunocompetent mice. Rechallenge of animals that rejected an IFNgamma-transfected EMT6 clone (EMT6-B17) with parental EMT6 cells resulted in tumor rejection, suggesting that IFNgamma-transfected EMT6 cells were able to induce long-term immunity. Mixing experiments using gene-transfected and unmodified tumor cells demonstrated that 10% of IFNgamma-transfected cells in the population was sufficient to protect mice against subsequent challenge with tumorigenic EMT6 cells. These studies demonstrate that the immunogenicity of tumor cells that are poorly responsive to exogenous IFNgamma can be enhanced by inserting and expressing the IFNgamma transgene. These findings also suggest a role for class II MHC in reducing tumorigenicity of the EMT6 tumor and inducing long-term tumor immunity.

Animals↗
PubMed1996

Endothelin-1 induces an increase in total protein synthesis and expression of the smooth muscle alpha-actin gene in vascular smooth muscle cells.

The growth response of aortic vascular smooth muscle cells (VSMCs) to chronic hypertension includes vascular hypertrophy. We have shown previously that angiotensin II positively regulates the expression of the human vascular smooth muscle (SM) alpha-actin gene. To further expand our understanding of vasoactive peptide-induced vascular hypertrophy, we studied endothelin-1 (ET-1) regulation of total protein synthesis and cytoskeletal gene expression in VSMCs. In a concentration-dependent manner ET-1 increased [3H] leucine incorporation by VSMCs (122.4 +/- 5.5%, mean +/- SEM, n = 5). ET-1 (0.1 microM) induced expression of SM alpha-actin mRNA as detected by Northern blot analysis. Also, ET-1 in a concentration-dependent manner (0.1 nM-0.1 microM) induced expression of the chloramphenicol acetyl transferase gene driven by 896 bp of the human SM alpha-actin promoter when transiently transfected into rat aortic VSMCs by the calcium phosphate method (141.2 +/- 9.8%, mean +/- SEM, n = 10). These data suggest that part of ET-1-induced increase in protein synthesis is achieved through transcriptional regulation of the SM alpha-actin gene via activation of cis-acting element(s) in the promoter. Such findings help elucidate the role of ET-1 in regulation of vascular growth.

Actins↗