The association of Epstein-Barr virus (EBV) with T cell lymphoproliferations and Hodgkin's disease: two new developments in the EBV field.
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Biomarkers↗
Biomedical subjects
X Zhou
Publications and source records attributed to X Zhou.
TFEC, a basic helix-loop-helix protein, forms heterodimers with TFE3 and inhibits TFE3-dependent transcription activation.
We have identified a new basic helix-loop-helix (BHLH) DNA-binding protein, designated TFEC, which is closely related to TFE3 and TFEB. The basic domain of TFEC is identical to the basic DNA-binding domain of TFE3 and TFEB, whereas the helix-loop-helix motif of TFEC shows 88 and 85% identity with the same domains in TFE3 and TFEB, respectively. Like the other two proteins, TFEC contains a leucine zipper motif, which has a lower degree of sequence identity with homologous domains in TFE3 and TFEB than does the BHLH segment. Little sequence identity exists outside these motifs. Unlike the two other proteins, TFEC does not contain an acidic domain, which for TFE3 mediates the ability to activate transcription. Like the in vitro translation product of TFE3, the in vitro-translated TFEC binds to the mu E3 DNA sequence of the immunoglobulin heavy-chain gene enhancer. In addition, the product of cotranslation of TFEC RNA and TFE3 RNA forms a heteromeric protein-DNA complex with mu E3 DNA. In contrast to TFE3, TFEC is unable to transactivate a reporter gene linked to a promoter containing tandem copies of the immunoglobulin mu E3 enhancer motif. Cotransfection of TFEC DNA and TFE3 DNA strongly inhibits the transactivation caused by TFE3. TFEC RNA is found in many tissues of adult rats, but the relative concentrations of TFEC and TFE3 RNAs vary considerably in these different tissues. No TFEC RNA was detectable in several cell lines, including fibroblasts, myoblasts, chondrosarcoma cells, and myeloma cells, indicating that TFEC is not ubiquitously expressed.
Amino Acid Sequence↗
Epicardial mapping of ventricular defibrillation with monophasic and biphasic shocks in dogs.
To study the mechanism of defibrillation and the reason for the increased defibrillation efficacy of biphasic waveforms, the potential gradient in a 32 x 30-mm region of the right ventricle in 15 dogs was progressively lowered in four steps while a strong potential gradient field was maintained throughout the rest of the ventricular myocardium. The volume of right ventricle beneath the plaque was 10 +/- 2% of the total ventricular mass. A 10-msec monophasic (eight dogs) or 5/5-msec biphasic (seven dogs) truncated exponential shock 30% above the defibrillation threshold voltage was given via electrodes on the left ventricular apex and right atrium to create the strong potential gradient field. Simultaneously, a weaker shock with the same waveform but opposite polarity was given via mesh electrodes on either side of the small right ventricular region to cancel part of the potential difference in the region and to create one of the four levels of potential gradient fields. Shock potentials and activations were recorded from 117 epicardial electrodes in the small region, and in one dog global epicardial activations and potentials were recorded from a sock containing 72 electrodes. Each gradient field was tested 10 times for successful defibrillation after 10 seconds of electrically induced fibrillation. For both monophasic and biphasic shocks, the percentage of successful defibrillation attempts decreased (p < 0.05) as the potential gradient decreased in the small region. Defibrillation was successful approximately 80% of the time for a mean +/- SD potential gradient of 5.4 +/- 0.8 V/cm for monophasic shocks and 2.7 +/- 0.3 V/cm for biphasic shocks (p < 0.05). No postshock activation fronts arose from the small region for eight waveform when the gradient was more than 5 V/cm. For both waveforms, the postshock activation fronts after the shocks were markedly different from those just before the shock and exhibited either a focal origin or unidirectional conduction.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Effects of monophasic and biphasic shocks on action potentials during ventricular fibrillation in dogs.
This study determined the response of action potentials during ventricular fibrillation (VF) to timed monophasic and biphasic shocks. A floating glass microelectrode was used to record intracellularly from the anterior right ventricle in 10 open-chest dogs. After 10 seconds of electrically induced VF, 5-millisecond monophasic and 2.5/2.5-millisecond biphasic shocks or 16-millisecond monophasic and 8/8-millisecond biphasic shocks were given via mesh electrodes on either side of the microelectrode. Monophasic and biphasic truncated exponential shocks of 5 V/cm were given with coupling intervals timed from the beginning of a VF action potential to the shock ranging from 50 to 70 milliseconds in 5-millisecond increments. Each coupling interval for each waveform was tested during a different VF episode. The interval between successive activations during VF was 86 +/- 15 milliseconds (mean +/- SD). The refractory period during VF was 61 +/- 5 milliseconds for 5-millisecond monophasic shocks and 66 +/- 6 milliseconds for 2.5/2.5-millisecond biphasic shocks (P < .05). At each coupling interval, action potential duration at 50% repolarization (APD50) was significantly prolonged by the shocks compared with the mean preshock APD50 (P < .05). ADP50 duration increased significantly with increases in the coupling interval (P < .05) for both monophasic and biphasic waveforms. For all coupling intervals together, APD50 prolongation as a percent of the mean preshock APD50 was 170 +/- 55%, 192 +/- 45%, 151 +/- 44%, and 175 +/- 45% for 5- and 16-millisecond monophasic and 2.5/2.5- and 8/8-millisecond biphasic waveforms, respectively. This APD50 prolongation was greater for monophasic than biphasic shocks and was greater for longer than shorter waveforms (P < .05). Thus, during VF, (1) the refractory period for 5-V/cm truncated exponential waveforms lasting 5 milliseconds is approximately 75% of the VF activation interval; (2) the refractory period is shorter for monophasic than for comparable biphasic waveforms; (3) both monophasic and biphasic 5-V/cm shock fields cause prolongation of action potential duration; (4) prolongation of action potential duration increases as the coupling interval increases; and (5) prolongation of action potential duration is greater for monophasic shocks and for longer shock waveforms.
Action Potentials↗
MMPs and proteinase inhibitors in the human aqueous humor.
PURPOSE: This study was performed to examine the gelatinolytic and caseinolytic activities and the levels of two proteinase inhibitors, alpha 1-proteinase inhibitor (alpha 1-antitrypsin) and alpha 2-macroglobulin, in the human aqueous humor. METHODS: Aqueous humor samples were collected during elective surgery in patients with cataracts. Zymography with gelatin- and casein-containing gels was performed. The inhibitors were examined by Western blot analyses, enzyme-linked immunosorbent assay, and dot blot assays. RESULTS: The aqueous humor contained a major band of gelatinolytic activity at a molecular weight of 66 kD and minor bands at 125, 95, and 62 kD. These gelatinases were inhibited by 10 mM ethylenediaminetetraacetic acid (EDTA) or 1,10-phenanthroline. After extended incubation (48 hours), zymography on casein-containing gels showed proteinase bands with molecular weights in the 80- to 84-kD range. Additional bands at 68 and 48 kD also were observed. All the caseinase activities were inhibited by 10 mM phenylmethylsulfonyl fluoride and 1 microgram/ml aprotinin. No inhibition was observed with 5 mM EDTA, 5 microM E-64, or 1 microM pepstatin. These results indicated that the caseinases are serine proteinases. Western blot analysis showed a 53-kD alpha 1-proteinase inhibitor band in the aqueous humor. The concentration was 32.2 +/- 9.9 micrograms/ml, constituting approximately 15% of the total protein. A 360-kD protein band immunoreactive to anti-alpha 2-macroglobulin also was detected. Its level in the aqueous humor was 3.2 +/- 1.3 micrograms/ml. CONCLUSIONS: The gelatinases, serine-like proteinases, and proteinase inhibitors found in the aqueous humor may participate in the remodeling of extracellular matrices in the trabecular meshwork and other tissues bordering the anterior chamber.
Aged↗
Parkinsonism induced with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in cats: behavioral, biochemical and pathological studies.
Intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in four cats produced akinesia, bradykinesia, crouched posture, feeding difficulty, and so on, lasting for two weeks. Madopar therapy ameliorated these motor impairments. Reduction of the concentration of dopamine and its metabolites was determined in the substantia nigra and putamen by high performance liquid chromatography (HPLC). Depletion of noradrenaline, serotonin and their metabolites was also seen. Loss of nerve cells and proliferation of glial cells in the substantia nigra were observed under the light microscope. The results indicate that MPTP-induced Parkinsonism in the cat provides an animal model that can be used for basic and therapeutic research on Parkinson's disease.
1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
The hypoxic moderation of systemic hypertension in spontaneously hypertensive rats.
The mechanism of hypoxic moderation of systemic systolic blood pressure was investigated in spontaneously hypertensive rats (SHR). Male SHR rats were divided into hypoxic (H, 5000 m for 15 d) and normoxic (N) groups. The systemic blood pressure of SHR-H (24.9 +/- 1.2 kPa) was found to be 3 kPa lower than that in SHR-N (27.0 +/- 1.3 kPa) (P < 0.05). This protective effect may have been related to the adaptive changes in vascular reactivity which manifested as an increase in the relaxation response of the aorta to ACh (P < 0.01) and a drop in its contraction in response to 5-HT (P < 0.05) following hypoxic exposure. The hypoxic moderating effect against the development of systemic hypertension may have also been related to the increased plasma levels of ANP observed.
Altitude↗
Effects of acupuncture on myoelectric activity of Oddi's sphincter in humans.
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Acupuncture Therapy↗
In vivo primary induction of virus-specific CTL by immunization with 9-mer synthetic peptides.
A primary cytotoxic T lymphocyte (CTL) response in vivo requires antigen presentation by cytosolic processing and can not in general be obtained by vaccination with soluble proteins. In the present work we have found that vaccination of mice with pre-processed synthetic peptides, corresponding to endogenous 9-mers produced in influenza A virus-infected cells, resulted in strong primary CTL responses. The generated CTL efficiently killed virus-infected target cells with preference for viral strains having the identical amino acid sequences to the peptides used for immunization. The optimal conditions for a primary in vivo CTL response was obtained with 100 micrograms peptide dissolved in incomplete Freund's adjuvant and injected s.c. at the base of tail. Spleen cells which had been primed 7-10 days earlier were restimulated for 5 days in vitro, using an optimal low peptide concentration (0.05 microM) and tested against virus-infected and peptide-treated target cells. The peptide-induced CTL were major histocompatibility complex class I restricted and CD8 positive.
Amino Acid Sequence↗
Class I restricted CTL recognition of a soluble protein delivered by liposomes containing lipophilic polylysines.
CD8+ cytotoxic lymphocytes recognize peptides derived from endogenous antigens complexed with class I major histocompatibility complex while CD4+ helper cells recognize peptides from exogenous antigens bound to class II MHC molecules. A soluble protein can be introduced into the class I pathway of antigen processing and presentation using an appropriate vehicle to deliver the antigen into the cytosol. Cationic liposomes containing lipophilic polylysine readily form complexes with an anionic, soluble protein ovalbumin. Mouse thymoma EL4 cells incubated with such complexes can be sensitized for killing by OVA-specific CTL effector cells. This method of target sensitization by a soluble antigen is more sensitive than the osmotic loading method previously reported.
Animals↗
Nonoxidative ethanol metabolism: expression of fatty acid ethyl ester synthase-III in cultured neural cells.
Alcohol metabolism in the human brain has been characterized as essentially nonoxidative in nature, with the esterification of ethanol with fatty acids via fatty acid ethyl ester synthase. This pathway of ethanol metabolism is related to end organ damage in the brain but the neural cell type expressing FAEES has not been identified. In this study human and rodent neuroblastoma and glioma cell lines are assayed for fatty acid ethyl ester synthase activity. Cells with neuronal properties demonstrated higher activity than glioma cell lines. We confirmed the presence of the mRNA for one type of synthase, fatty acid ethyl ester synthase-III in three neuronal cell lines--N1E115 cells, PC12 cells, and SK-N-MC cells. These results support the hypothesis that FAEES activity is expressed chiefly in cells with neuronal properties and suggest that non-oxidative ethanol metabolism is potentially related to the toxic effect of ethanol on the human brain.
Acyltransferases↗
Molecular cloning and characterization of a novel rat activin receptor.
We report the isolation of a full-length rat cDNA for a new activin receptor. The deduced amino acid sequence of this receptor shows 67 percent overall identity with that of a previously identified mouse activin receptor. As predicted for the mouse activin receptor, the amino acid sequence of the rat receptor is consistent with a polypeptide containing an extracellular ligand binding domain, a hydrophobic transmembrane domain, and a serine/threonine kinase intracellular domain. In an expression assay, this new receptor was found to bind I125 radiolabeled activin.
Activin Receptors↗
Insertional mutation of a gene involved in growth regulation of the early mouse embryo.
A transgenic mouse strain derived from embryonic stem (ES) cells infected with multiple copies of a retroviral vector carries a recessive insertional mutation resulting in prenatal lethality. A detailed histological analysis of developing embryos has shown that the mutation results in hyperplasia of both embryonic and extraembryonic ectoderm and failure of mesoderm formation in the egg cylinder stage embryo. The number of cells in each lineage of normal and mutant embryos was estimated using stereological analysis of serial sections taken from implantation sites. We observed a 2-fold increase in the number of embryonic ectoderm cells in mutant embryos at 7.5 days postcoitum (dpc). In addition, we found that mutant embryonic ectoderm cells are only 0.6 times as large as normal cells. The number of extraembryonic ectoderm cells in mutant embryos at 7.5 dpc is also increased, by almost 4-fold. Mutant extraembryonic ectoderm cells are also smaller than normal, being only two-thirds the size of wild-type cells. The mutant phenotype suggests that the gene identified by this insertional mutation plays an important role in the growth control of early embryonic lineages.
Animals↗
In vivo priming of cytotoxic T lymphocyte responses in relation to in vitro up-regulation of major histocompatibility complex class I molecules by short synthetic peptides.
Cytotoxic T lymphocytes (CTL) recognize target antigens as short peptides presented by major histocompatibility complex class I molecules (MHC-I). Externally added peptides can sensitize target cells by binding directly to MHC-I without any need for internal processing. Those which are similar in length to endogenously processed peptides are more potent in this respect than slightly longer peptides. Peptide MHC-I interactions can also be reflected as up-regulation of MHC-I in vitro on certain cells. We have compared the capacity of Db, Kb- and Ld-binding peptides, which are slightly different in length, to up-regulate MHC-I in vitro with their immunogenicity in vivo, in relation to generation of CTL responses. A clear correlation between these two different functions was found. We have also modified a 9-mer Db-binding peptide by adding cystein to the amino terminus and lysine to the amino- or carboxy terminus and studied the effects on MHC-I up-regulation and in vivo immunogenicity. Cystein and lysine contain reactive groups which are likely to influence the binding of modified peptides into the antigen-binding groove of Db. These small modifications of the optimal 9-mer peptide strongly influenced their functions but still there was a correlation between MHC-I up-regulation and CTL responses. Up-regulation of MHC-I in vitro may reflect a capacity of peptides to accumulate on the surface of particular antigen-presenting cells in vivo.
Amino Acid Sequence↗
Sexuality in a natural population of bacteria--Bacillus subtilis challenges the clonal paradigm.
Reproduction by binary fission necessarily establishes a clonal genotypic structure in bacterial populations unless a high rate of genetic recombination opposes it. Several genetic properties were examined for a wild population of Bacillus subtilis in the Sonoran Desert of Arizona to assess the extent of recombination in a natural population. These properties included allozyme variation revealed by multilocus enzyme electrophoresis, phage and antibiotic resistance, and restriction fragment length polymorphism with Southern hybridization. Evidence of extensive genetic recombination was found along with evidence of modest clonal structure. Recombination must be frequent relative to binary fission in this population. This mixed population structure provides broader options for bacterial evolution than would a purely clonal structure.
Bacillus subtilis↗
Ethanol inhibits C6 cell growth: fetal alcohol syndrome model.
Maternal consumption of ethanol produces a pattern of malformations, including nervous system abnormalities, in the developing fetus, a state called Fetal Alcohol Syndrome. We report the dose-dependent inhibition by ethanol of the growth of a glioma derived cell line, C6 cells; the effects occur at ethanol concentrations commonly encountered in the blood during human intoxication. The effects occur with different morphological subtypes of the cell line and do not occur when the cells are exposed to iso-osmolar concentrations of other chemicals. The results demonstrate that C6 cells are a model for the study of the effects of ethanol on nervous system cell growth.
Astrocytes↗
H-K-ATPase enhancement of Rb efflux by cortical collecting duct.
Previous studies suggest that enhancement of rubidium tracer (86Rb) lumen-to-bath efflux following removal of luminal Na is mediated in part by a Ba-insensitive pathway. To determine the role of a primary active K pump in this response, we examined the action of known inhibitors of H-K-ATPase (Sch 28080) and Na-K-ATPase (ouabain) on the 86Rb lumen-to-bath efflux coefficient (KRb). Luminal Sch 28080 (10 microM) significantly reduced KRb by 39 +/- 8.0% (P less than 0.05), whereas luminal ouabain (0.1 mM) reduced KRb by 10 +/- 14% (P = not significant), suggesting that a luminal H-K-ATPase mediates Rb efflux. To examine whether H-K-ATPase mediates Rb in KRb following removal of luminal Na, additional experiments were conducted to examine the effect of Sch 28080 on KRb in the presence and the absence of luminal Na. In the presence of luminal Na, 10 microM Sch 28080 reduced KRb by 15 +/- 5.0%. However, in the absence of luminal Na, 10 microM Sch 28080 decreased KRb by 48 +/- 8.2%. The percentage inhibition of KRb by Sch 28080 was significantly greater in the absence of luminal Na than in its presence (P less than 0.01), suggesting that the enhancement of KRb following removal of luminal Na is mediated in part by an H-K-ATPase pathway. In either case transepithelial voltage was not significantly altered. In contrast to the lack of effect of luminal ouabain, addition of 0.1 mM ouabain to the bath increased KRb (69.8 +/- 11.1 vs. 95.9 +/- 18.7 nm/s, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Adenosine Triphosphatases↗
Mechanisms of rubidium permeation by rabbit cortical collecting duct during potassium restriction.
To examine the pathways of K permeation in the cortical collecting duct (CCD) from K-restricted rabbits, we studied the effects of the following three maneuvers: 1) luminal amiloride addition; 2) luminal Ba addition; and 3) luminal Na removal. Luminal addition of amiloride (1 mM) significantly increased the 86Rb lumen-to-bath efflux coefficient (KRb), and this effect was fully blocked by the presence of 2 mM luminal Ba. Addition of 2 mM luminal Ba reduced KRb both in the absence of luminal Na and in the presence of luminal Na. In contrast to the effect of amiloride addition, removal of luminal Na significantly increased KRb, but neither 2 mM luminal Ba nor 4 mM luminal Ba totally abolished this effect. However, simultaneous addition of luminal Ba and Sch 28080 (10 microM) fully inhibited the increase in KRb upon luminal Na removal, indicating that luminal Na removal enhances Rb efflux in part via H-K-adenosinetriphosphatase (H-K-ATPase). To test whether Na acts as a partial agonist for cation efflux via the H-K-ATPase we examined the effect of Sch 28080 on the 22Na lumen-to-bath efflux coefficient (KNa). These studies were conducted in the presence of 0.1 mM luminal amiloride to block fully apical conductive Na efflux, and the effect of Sch 28080 on KNa was examined at two different ambient K concentrations. In the presence of 0.5 mM K, Sch 28080 (10 microM) significantly inhibited KNa from 47.6 +/- 4.8 to 35.0 +/- 6.8 nm/s (P < 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗