Novel mechanism and factor for regulation by HIV-1 Tat

Tat regulation of human immunodeficiency virus (HIV) transcription is unique because of its specificity for an RNA target, TAR, and its ability to increase the efficiency of elongation by polymerase. A reconstituted reaction that is Tat-specific and TAR-dependent for activation of HIV transcription has been used to identify and partially purify a cellular activity that is required for trans-activation by Tat, but not by other activators. In the reaction, Tat stimulates the efficiency of elongation by polymerase, whereas Sp1 and other DNA sequence-specific transcription factors activate the rate of initiation. Furthermore, while TATA binding protein (TBP)-associated factors (TAFs) in the TFIID complex are required for activation by transcription factors, they are dispensable for Tat function. Thus, Tat acts through a novel mechanism, which is mediated by a specific host cellular factor, to stimulate HIV-1 gene expression.

The yeast TATA-binding protein (TBP) core domain assembles with human TBP-associated factors into a functional TFIID complex

In mammalian and Drosophila cells, the central RNA polymerase II general transcription factor TFIID is a multisubunit complex containing the TATA-binding protein (TBP) and TBP-associated factors (TAFs) bound to the conserved TBP carboxy-terminal core domain. TBP also associates with alternative TAFs in these cells to form general transcription factors required for initiation by RNA polymerases I and III. Although extracts of human HeLa cells contain little TBP that is not associated with TAFs, free TBP is readily isolated from yeast cell extracts. However, recent studies indicate that yeast TBP can also interact with other yeast polypeptides to form multiprotein complexes. We established stable human HeLa cell lines expressing yeast TBP and several yeast-human TBP hybrids to study TBP-TAF interactions. We found that the yeast TBP core domain assembles with a complete set of human TAFs into a stable TFIID complex that can support activated transcription in vitro. The fact that the yeast TBP core, which differs from human TBP core in approximately 20% of its amino acid residues, has the structural features required to form a stable complex with human TAFs implies that Saccharomyces cerevisiae probably contains TAFs that are structurally and functionally analogous to human TAFs. Surprisingly, the non-conserved amino terminus of yeast TBP inhibited association between the yeast core domain and human TAFs.

Nitric oxide release from resting human platelets

In this study, we have investigated the release of nitric oxide from resting human platelets. Nitric oxide was detected and quantitated by either measuring the conversion of oxy-hemoglobin to met-hemoglobin or generation of nitrite and nitrate by the cells. Nitric oxide was released from both intact resting platelets and platelets activated by collagen. Nitric oxide release was proportional to platelet concentration, and was equivalent to approximately 4.5 +/- 0.6 pmol (or 2.8 +/- 0.3 pmol in the presence of prostaglandin I2) and 11.2 +/- 1.3 pmol nitric oxide released per minute per 10(8) cells at 37 degrees C for resting platelets and platelets activated by collagen, respectively. The generation of nitric oxide by resting platelets was linear with respect to time over a two hour period, while the release of nitric oxide from platelets following activation was transient and was linear for only the first 10 min, after which it slowed to completion at approximately 30 min. The release of nitric oxide was it slowed to completion at approximately 30 min. The release of nitric oxide was stimulated by L-arginine, but was inhibited by L-nitro-arginine methyl ester (L-NAME). The inhibitory effect of L-NAME could be reversed by addition of L-arginine. The release of nitric oxide from platelets was also partially inhibited by prostaglandin I2, prostaglandin E1, aspirin and EDTA. The amount of nitric oxide released from resting platelets compared with that released from endothelial cells suggests that platelet-derived nitric oxide may play a significant role in the maintenance of vascular tone and blood flow.

Alcohols potentiate ion current mediated by recombinant 5-HT3RA receptors expressed in a mammalian cell line

The effect of acute exposure to alcohols on ion current mediated by recombinant 5-HT3RA receptors transiently expressed in human embryonic kidney 293 cells was investigated. Cells transfected with 5-HT3RA cDNA expressed receptors with pharmacological and functional properties similar to those of native 5-HT3 receptors. Potentiation of receptor-mediated cation current was observed in the presence of ethanol (10-100 mM), butanol (0.1-20 mM), isopentanol (0.01-25 mM) and trichloroethanol (0.5-25 mM). Potentiation increased in a concentration-dependent manner until saturation was achieved for all alcohols tested. The maximal efficacies of potentiation differed among the alcohols with isopentanol > butanol = trichloroethanol > ethanol. Potentiation by butanol and isopentanol appeared to show acute tolerance such that the percent increase in current amplitude was largest upon the first of a series of alcohol applications and decreased during subsequent applications. The effect of ethanol was variable with potentiation occurring in 74% of cells examined, but not in the remaining cells. These observations indicate that the potentiating action of alcohols is similar in recombinant receptors to that previously observed in neuroblastoma cells and neurons expressing native receptors. These findings indicate that this recombinant system is suitable for studying the molecular basis of alcohol actions on the 5-HT3 receptor.

Cholesterol oxides in plasma and lipoproteins of magnesium-deficient rabbits and effects of their lipoproteins on endothelial barrier function

The cholesterol oxide (ChO) levels in the plasma and low density lipoproteins (LDL and VLDL) in four groups of rabbits fed for seven weeks either normal (NC) or high cholesterol (HC) with low or normal magnesium (Mg) diets were determined and compared with the NC group fed a standard rabbit diet. The plasma from the NC group contained low levels of different cholesterol oxides. These cholesterol oxides were significantly elevated in the plasma of rabbits fed a HC-normal magnesium or a HC-low magnesium diet. In the NC-low Mg group, 7 alpha-hydroxycholesterol, 7 beta-hydroxycholesterol and 7-ketocholesterol were elevated while the other cholesterol oxides remained within the normal range of the NC group. When the cholesterol oxides were assayed in the LDL and VLDL fractions as micrograms/mg protein, the fractions obtained from the groups fed NC-low Mg, HC-normal Mg or HC-low Mg diets showed higher levels of cholesterol oxides than the fractions obtained from the NC group. When LDL and VLDL fractions from the different groups were incubated at equal protein concentration with confluent endothelial cell monolayers, transendothelial albumin transfer was significantly increased by the lipoproteins from the experimental groups as compared to the control group. These results suggest that elevation of cholesterol oxides in magnesium deficiency or hypercholesterolaemia may be related to their atherogenic effects through decreasing the endothelial barrier function which could enhance the deposition of cholesterol rich lipoproteins into the arterial wall.

[The frozen bovine RPE cells release a resolvable material which can promote the proliferation of RPE cells]

3H-thymidine incorporation (as a proliferation maker) confirms that the frozen bovine RPE cells release a resolvable material which can promote the proliferation of RPE cells, and the molecular weight of the material is more than 10,000 Daltons. This result provided some new explanations about the effect and complications of ophthalmic cryotherapy related to RPE.

Changes in p53 and cyclin D1 protein levels and cell proliferation in different stages of human esophageal and gastric-cardia carcinogenesis

The objective of this study was to quantify the changes in p53 and cyclin D1 protein levels in different stages of human esophageal and gastric cardia carcinogenesis in a high-risk population in Henan, China. Immunoreactivity of p53, cyclin D1 and proliferating-cell nuclear antigen (PCNA) was observed in the cell nuclei of esophageal and gastric cardia biopsies. The number of p53-immunostaining-positive cells was low in normal epithelia, slightly increased in basal-cell hyperplasia (BCH), markedly increased in dysplasia (DYS) (10-fold), and further increased in squamous-cell carcinoma (SCC) (40-fold). This pattern of change was similar to that of cell proliferation as indicated by PCNA immunostaining. On the other hand, the number of cyclin D1-immunostaining-positive cells did not increase from BCH to DYS, although a slight increase from DYS to SCC was noted. In the gastric cardia, again, the pattern of change of p53-positive cells in different stages of lesions paralleled the pattern of cell proliferation. The number of p53-positive cells was very low, much lower than that of PCNA-positive cells, in normal, chronic superficial gastritis (CSG) and chronic atrophic gastritis (CAG); therefore, the increase of p53-positive cells from CAG to DYS was more dramatic (100-fold). From DYS to adenocarcinoma (AC), the p53-positive and the PCNA-positive cells increased 4-fold. On the other hand, the number of cyclin D1-positive cells did not increase in pre-cancerous lesions, but increased slightly in AC. This study demonstrates that p53 protein accumulation increased with the progression of pre-cancerous lesions, especially in the genesis of dysplasia, both in the esophagus and in the gastric cardia. Our approach of quantitative immunohistochemistry sheds light on the mechanisms of genesis of esophageal and gastric-cardia cancers, which frequently occur together in many high-incidence areas.

Optical sensors for monitoring and control of plant growth systems

Optical chemical sensors have been developed for monitoring several parameters relevant to plant growth systems. These sensors utilize porous polymer and porous glass as the sensing element, and optical fiber input/output lines connected to a custom optoelectronic interface. Present in the sensing element are immobilized colorimetric indicators, which react with the analyte to be sensed. This reaction results in a change in the optical properties of the sensor. These sensors are particularly suited to in-situ monitoring of nutrient solution parameters and atmospheric trace contaminants in life support and plant growth systems. Sensors for monitoring pH, ammonia, and ethylene will be discussed.

Vasoinhibitory effects of NC 1005 and NC 1006, new synthesized antiarrhythmic agents, in isolated rat aorta

1. NC 1005 and NC 1006 (3 x 10(-6) M-10(-4) M) inhibited the contractions induced by phenylephrine (PE) and KCl in isolated rat aortas with or without endothelium. 2. In a Ca(2+)-free medium containing EGTA and nifedipine, NC 1005 and NC 1006 inhibited PE-response and a subsequent response to Ca2+ in the presence of PE. 3. NC 1005 and NC 1006 also caused relaxations of endothelium-removed aortas precontracted with PE. 4. The relaxations induced by NC 1005 and NC 1006 were potentiated by amiloride, zaprinast and theophylline but not by increasing the external Na+ concentration. 5. Methylene blue and ouabain slightly potentiated NC 1005-relaxation, but not NC 1006-relaxation. 6. Glyburide, apamine and nifedipine had no effect on the relaxations. 7. NC 1005 and NC 1006 potentiated the relaxation induced by nitroglycerin (NG) without affecting isoproterenol-relaxation. 8. In the presence of forskolin, NC 1005 and NC 1006 failed to potentiate NG-relaxation. 9. These results suggest that the vasoinhibitory effects of NC 1005 and NC 1006 may be due to an increase in the level of cAMP.

Repeated polyketide synthase modules involved in the biosynthesis of a heptaene macrolide by Streptomyces sp. FR-008

Genes for biosynthesis of a Streptomyces sp. FR-008 heptaene macrolide antibiotic with antifungal and mosquito larvicidal activity were cloned in Escherichia coli using heterologous DNA probes. The cloned genes were implicated in heptaene biosynthesis by gene replacement. The FR-008 antibiotic contains a 38-membered, polyketide-derived macrolide ring. Southern hybridization using probes encoding domains of the type I modular erythromycin polyketide synthase (PKS) showed that the Streptomyces sp. FR-008 PKS gene cluster contains repeated sequences spanning c. 105kb of contiguous DNA; assuming c. 5 kb for each PKS module, this is in striking agreement with the expectation for the 21-step condensation process required for synthesis of the FR-008 carbon chain. The methods developed for transformation and gene replacement in Streptomyces sp. FR-008 make it possible to genetically manipulate polyene macrolide production, and may later lead to the biosynthesis of novel polyene macrolides.

[Detection of P-glycoprotein expression in patients with acute leukaemia and clinical significance]

Anti-P-glycoprotein monoclonal antibody JSB-1 and alkaline phosphatase-anti-alkaline phosphatase (APAAP) immunocytochemical staining technique were used to study the relation between P-glycoprotein expression and clinical multidrug resistance (MDR) in 42 patients with acute leukaemia (23 ALL and 19 ANLL). 10 of 17 patients who were diagnosed as refractory or relapsed acute leukaemia were positive with P-glycoprotein expression, while only 3 of 14 newly diagnosed and 1 of 11 who were in complete remission were positive. The preliminary results indicated that there was a close association between the P-glycoprotein expression and the clinical resistance to chemotherapy in some patients.

[Experimental study of kangli san in treating viral hyperpyrexia]

The hypothermic effect of Kangli San (KLS) on the model of rabbit viral hyperpyrexia caused by rabbit hemorrhagic fever virus was studied. Intraperitoneal injection of 200% KLS (4g/kg) could inhibit the pyrogenic action of the virus efficiently. The results showed that KLS could decrease the function of pyrogenic transmitters such as PGE2 and cAMP etc. in cerebrospinal fluid.

p53 tumor suppressor gene mutation in early esophageal precancerous lesions and carcinoma among high-risk populations in Henan, China

To understand whether p53 gene mutation is an early or late event in esophageal carcinogenesis, biopsy samples of esophageal epithelium from symptom-free subjects in a high incidence area, Huixian county of Henan Province, China, were analyzed. Mutations in exons 5, 6, 7, and 8 of p53 were analyzed by single-strand conformation polymorphism analysis and DNA sequencing. Among the 37 biopsy samples showing accumulation of p53 protein in immunohistochemical staining, missense mutations of p53 gene were detected in 1 of 3 samples with normal epithelia, 3 of 23 samples with basal cell hyperplasia, and 4 of 11 samples with dysplasia. All mutations occurred at exon 5 with 3 at codon 175, 2 at codon 176, and 1 each at codons 159, 135, and codon 132. Of the 8 mutations, there were 3 G to A transitions and 3 G to T transversions. To understand the mutation spectrum and possible causative factors of esophageal cancer in this area, surgically resected human primary esophageal carcinomas from Linxian county were analyzed for p53 gene mutations in exons 5, 6, 7, and 8. Mutations were detected in 16 of 29 samples (55%). Twelve samples contained different missense point mutations, with 75% transitions (7 G to A and 2 A to G) and 25% transversions (2 G to T and 1 G to C). Most of the mutations were located at either exon 5 or exon 7. A deletion and an insertion of nucleotides leading to frame-shift mutations were detected in each of two other samples. The results demonstrate that p53 protein accumulation and gene mutation may occur at very early stages of esophageal carcinogenesis. In carcinomas, there was a higher frequency of p53 gene mutations, which accounts for most of the cases with p53 protein accumulation.

Inhibitory effect of sodium nitroprusside on the relaxing action of isoproterenol in isolated rat urinary bladder

1. Isoproterenol caused relaxation of rat detrusor muscles contracted by electrical stimulations. Sodium nitroprusside (SNP) and methylene blue inhibited the relaxation induced by isoproterenol without affecting forskolin-induced relaxation. 2. In the presence of theophylline, zaprinast still potentiated isoproterenol-relaxation. In the presence of butoxamine, a selective beta 2-adrenoceptor inhibitor, but not metoprolol, a selective beta 1-adrenoceptor inhibitor, SNP still inhibited isoproterenol-relaxation. 3. SNP inhibited the relaxation to dobutamine, a beta 1-adrenoceptor agonist but not that to terbutaline, a beta 2-adrenoceptor agonist. The relaxation to dobutamine was also inhibited by methylene blue. Further, in the presence of theophylline, zaprinast still potentiated dobutamine-relaxation. 4. Isoproterenol increased tissue level of cGMP, which was inhibited by propranolol. 5. These results suggest a possibility that, in rat detrusor muscles, isoproterenol causes relaxation due to increases in the level of both cAMP and cGMP.

The influence of 25-hydroxycholesterol on phosphatidylinositol content in cultured smooth muscle cells

The effect of 25-hydroxycholesterol on phosphatidylinositol content was studied in subconfluent human arterial smooth muscle cells exposed to myo-[2-3H]inositol for 90 min and then to 25-hydroxycholesterol at different concentrations or for different incubating periods. Ethanol at a concentration of 0.05% in culture medium was used as control. The results demonstrate that an increased incubation time or an increase in the concentration of 25-hydroxycholesterol produced an increase in phosphatidylinositol and its degraded products. The ratio of precursor to product at each stage of phosphatidylinositol turnover in 25-hydroxycholesterol-treated cells, however, was not different from that in control cells. The data indicate that the presence of 25-hydroxycholesterol in the media induced general activation of phosphatidylinositol synthesis and turnover.

Possible mechanisms of vasoinhibitory effects of mequitazine, an antiallergic agent, on the contractions of isolated rat aorta induced by K+, phenylephrine, 5-hydroxytryptamine, and Ca2+

Mequitazine, 10-(3-quinuclidinylmethyl) phenothiazine, inhibited contractile responses to KCl, phenylephrine (PE), 5-hydroxytryptamine (5-HT), and Ca2+ in rat aorta. Indomethacin or removal of endothelium did not affect the inhibitory effect of mequitazine on the responses to PE. In Ca(2+)-free medium containing EGTA and nifedipine, mequitazine inhibited both residual response to PE and subsequent response to Ca2+ in the presence of PE. Mequitazine potentiated the relaxation to nitroglycerin (NTG) and isoproterenol. In the presence of forskolin, mequitazine did not cause further potentiation of NTG relaxation. Mequitazine relaxation was slightly inhibited by nifedipine and was potentiated by theophylline. The relaxation was not affected by zaprinast, methylene blue, W-7, propranolol, cimetidine, glyburide, or tetraethylammonium. Tissue level of cyclic AMP in rat aorta was increased by mequitazine. These results suggests that mequitazine may inhibit voltage-operated Ca2+ channels (VOC) and increases the level of cyclic AMP.

Development of a gene cloning system for Streptomyces hygroscopicus subsp. yingchengensis, a producer of three useful antifungal compounds, by elimination of three barriers to DNA transfer

Streptomyces hygroscopicus 10-22 could not be transformed with any of the commonly used Streptomyces plasmid vectors and was resistant to plaque formation by the Streptomyces phages phi C31 and R4. Repeated selection resulted in the isolation of derivatives of S. hygroscopicus 10-22 that could be transformed with pIJ101- and pJV1-derived cloning vectors and of restriction-deficient derivatives that could accept DNA propagated in Streptomyces lividans 66. These new strains, which include three that still produce the original antibiotics, can be used as hosts for gene cloning. Insertion of nonreplicating vectors by homologous recombination and transposition of Tn4560 were demonstrated in S. hygroscopicus 10-22.

Defibrotide stimulates expression of thrombomodulin in human endothelial cells

Cultured human umbilical vein endothelial cells were incubated with defibrotide at concentrations of 0, 5, 50 and 500 micrograms/ml for 4 and 24 h respectively. Thrombomodulin activity and molecules on the surface of the cells were determined by chromogenic assay and radioimmunoassay, thrombomodulin antigen in endothelial cells and in conditioned medium of the cells was measured by immunoradioassay. Thrombomodulin mRNA within the cells was analysed by slot blot. After 24 h of incubation, the activity and molecules of thrombomodulin on the surface of endothelial cells, as well as the antigen and mRNA of thrombomodulin in the cells were significantly increased in a dose dependent manner. However, the level of thrombomodulin antigen in conditioned medium was about equal to that of the control. Our data indicate that defibrotide stimulates expression of thrombomodulin in human endothelial cells. These beneficial effects may play a role in antithrombotic activity of defibrotide.

Effect of dietary magnesium deficiency with/without cholesterol supplementation on phospholipid content in liver, plasma and erythrocytes of rabbits

The effect of magnesium deficiency with/without supplementary cholesterol on phospholipid content in liver, plasma and erythrocytes was investigated in New Zealand White male rabbits. After the rabbits had been fed a low magnesium and/or high cholesterol diet for seven weeks, the phospholipid content in liver, plasma and erythrocytes was measured. Dietary magnesium deficiency produced a marked elevation of total phospholipid and certain individual phospholipids in the rabbit liver. The elevation was accentuated by cholesterol supplementation. In the plasma, a low magnesium intake enhanced plasma phosphatidylcholine, phosphatidic acid, phosphatidylinositol, and sphingomyelin, but an activated conversion from phosphatidylethanolamine to phosphatidylcholine made the increase in phospholipid insignificant. On the other hand, a low magnesium intake restricted the increase in magnitude of phospholipid caused by cholesterol supplementation. In the erythrocytes, total phospholipid, phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine were decreased by a low magnesium and/or a high cholesterol intake. We suggest that the increased contents of total phospholipid and/or certain individual phospholipids in the livers and plasma resulted from the enhanced synthesis of phospholipid in the liver by low magnesium intake. A decreased utilization of food by low magnesium diet limited the magnitude of plasma phospholipid increase produced by cholesterol supplementation.

Effect of octreotide on dynamic excretion of bile in Chinese acromegalic patients assessed by [99mTc]EHIDA hepatobiliary scan

We used [99mTc]EHIDA hepatobiliary scintigraphy to determine whether both hepatic bile secretion and gallbladder contractility are suppressed in acromegalic patients receiving long-term treatment with the somatostatin analogue octreotide. We studied three groups of patients: group 1, untreated patients; group 2, average dose of octreotide 500 +/- 100 micrograms/day for 33 +/- 4 months; and group 3, 1000 +/- 200 micrograms/day for 33 +/- 4 months. Images were taken at specified time intervals during the 120-min period following injection of EHIDA. After a single injection of octreotide, group 1 patients demonstrated delayed visualization of the radioisotope in the liver, gallbladder, and duodenum. At the end of long-term treatment, group 2 patients showed a delay in appearance of maximal radioactivity in the gallbladder. Two weeks following discontinuation of octreotide, this parameter had decreased significantly (P < 0.001). In group 3, visualization of the liver, gallbladder, and duodenum were prolonged, with delayed visualization of the gallbladder persisting two weeks after withdrawal (P < 0.005). These results indicate that gallbladder contractility is decreased after a single injection of octreotide and that during chronic octreotide therapy the rate of bile secretion is reduced. Impaired gallbladder contractility normalizes more rapidly after discontinuation of octreotide in patients receiving low doses of the analog.

GM3 directly inhibits tyrosine phosphorylation and de-N-acetyl-GM3 directly enhances serine phosphorylation of epidermal growth factor receptor, independently of receptor-receptor interaction

GM3 ganglioside (II3NeuAcLacCer) inhibits epidermal growth factor (EGF)-dependent receptor autophosphorylation and cell growth (Bremer, E.G., Schlessinger, J., and Hakomori, S. (1986) J. Biol. Chem. 261, 2434-2440), whereas de-N-acetyl-GM3 (deNAcGM3; II3NeuNH2Lac-Cer) promotes these processes (Hanai, N., Dohi, T., Nores, G. A., and Hakomori, S. (1988) J. Biol. Chem. 263, 6296-6301). Receptor-receptor interaction has been proposed as an essential initial mechanism for EGF-dependent activation of EGF receptor kinase (EGF-RK) (Schlessinger, J. (1988) Trends Biochem. Sci. 13, 443-447). We studied the effects of GM3 and deNAcGM3 on EGF-RK function and EGF-R dimerization, and observed that (i) EGF-dependent in vitro and in vivo (in situ) phosphorylation of A431 cells at both monomeric and dimeric forms of EGF-R was inhibited in a dose-dependent manner by GM3, but unaffected by GM1. (ii) Quantities of both forms of EGF-R remained constant regardless of addition of various quantities of GM3 or GM1, as revealed by blotting with antibodies directed to the C-terminal region of EGF-R, or by cell surface 125I-labeling followed by immunoprecipitation. (iii) DeNacGM3 in the absence as well as in the presence of a minimal quantity of detergent significantly enhanced EGF-R phosphorylation, particularly Ser phosphorylation. (iv) DeNAcGM3 was detected in a large variety of actively growing tumor cells. Findings i and ii above indicate that GM3 directly inhibits EGF-dependent Tyr phosphorylation but does not affect receptor-receptor interaction. Findings iii and iv suggest that deNAcGM3 strongly promotes serine phosphorylation (in addition to Tyr phosphorylation) of EGF-R and may function as a second messenger in the process of cell growth stimulation.

Vasoinhibitory action of KT2-734, an antihypertensive agent, in isolated rat aorta

In rat aorta, KT2-734 inhibited contractile responses to 5-hydroxytryptamine (5-HT) and KCl. KT2-734 inhibited the relaxing effect of verapamil, but not nifedipine. Similarly, verapamil, but not nifedipine, inhibited the vasorelaxing effect of KT2-734. KT2-734 relaxation was inhibited by endothelium removal but not by atropine and propranolol. Methylene blue, a guanylyl cyclase inhibitor, and NG-monomethyl arginine also inhibited the relaxation both in the presence and absence of endothelium. In the absence of endothelium, KT2-734 potentiated the relaxation induced by L-arginine, nitroglycerin and isoproterenol. In addition, M & B 22,948, a cGMP phosphodiesterase inhibitor, and theophylline inhibited and potentiated, respectively, KT2-734-induced relaxation. However, methylene blue inhibited the potentiation of isoproterenol relaxation by KT2-734 and that of KT2-734-relaxation by theophylline. KT2-734 caused increases in the level of cGMP without significantly affecting the cAMP level. These results suggest that KT2-734 may cause endothelium-independent relaxation mainly due to inhibition of cGMP-phosphodiesterase.

IR circular dichroism of turns in small peptides

The observation of circular dichroism (CD) in vibrational transitions in the infrared spectral region offers new possibilities for the determination of peptide solution conformation. Infrared or vibrational CD (VCD) is a particularly sensitive probe for the conformation of various peptide turns. Results of small linear and cyclic peptides containing beta- or gamma-turns are reported.

Possible involvement of NMDA receptor-mediated transmission in barbiturate physical dependence

1. The competitive antagonists at the N-methyl-D-aspartate (NMDA) receptor, CGP39551 and CGP37849, protected against the barbiturate withdrawal syndrome in mice, as measured by ratings of convulsive behaviour on handling. 2. The effective doses of these compounds were lower than those required to prevent seizures due to NMDA in naive animals; these were in turn lower than those needed to prevent the convulsive effects of the alpha-aminobutyric acid (GABA) antagonist, bicuculline. 3. The NMDA-receptor antagonists did not alter the increase in the incidence of convulsions due to the GABAA antagonist, bicuculline, that is seen during barbiturate withdrawal, although the latencies to these convulsions during barbital withdrawal were significantly increased after CGP39551. 4. Barbiturate withdrawal did not affect the convulsive actions of NMDA, whether measured by the incidence of convulsions or by intravenous infusion. 5. The Bmax for [3H]-dizocilpine ([3H]-MK801) binding was significantly increased by chronic barbital treatment in cerebrocortical but not in hippocampal tissues, while the Kd remained unaltered in either case. 6. At 1 h and 24 h after administration of a single dose of barbitone, the Bmax for [3H]-dizocilpine binding was unaltered in cerebrocortical tissue. Acute addition of barbitone in vitro did not alter [3H]-dizocilpine binding or the displacement of binding of thienylcyclohexylpyridine.

Factors affecting electrofusion of 2-cell mouse embryos

Parameters of electrofusion of 2-cell mouse embryos were optimized for application as a model for nuclear transplantation. There was considerable lysis of embryos with M(2) as the medium for fusion; however, 100% fusion (n = 58) was obtained with a single 0.31-kv / cm, 1280-musec pulse. With mannitol and sucrose solutions as the medium, a wide range of field strengths (0.31-1.41 kv / cm for 0.26 M sucrose solution and 0.31 to 2.04 kv / cm for 0.3 M mannitol solution) and durations of the electrical pulse (10-1280 musec) resulted in high rates of fusion (often 100%). Likewise, osmolarity of sucrose and mannitol solutions did not affect the rate of fusion using a 0.47-kv / cm pulse. With a field strength of 2.04 kv / cm, the proportion of embryos that fused in mannitol solution increased (P<0.05) and the proportion that were lysed decreased (P<0.05) as osmolarity increased. Both fused (162 642 , 25%) and control embryos (32 72 , 44%) continued to develop in culture for 48 h, after which they began to compact. Fused embryos were only at the 4-cell stage by this time, while control embryos were at the 8-cell stage. Optimal pulse durations are plotted for field strengths between 0.31 and 1.41 kv / cm with 0.26 M sucrose as fusion medium.

Association between proto-oncoprotein Rel and TATA-binding protein mediates transcriptional activation by NF-kappa B

The c-Rel protein is able to associate in vitro and in vivo with the TATA-binding protein (TBP) of the TFIID complex. Coexpression of TBP with c-Rel augments transactivation from the kappa B site in Drosophila Schneider cells. DNA-binding mutants of TBP not only fail to cooperate, but they repress transactivation by c-Rel. There may be a direct communication between kappa B enhancer binding proteins and basal transcription factors which leads to enhanced transcription.

Conversion of a dorsal-dependent silencer into an enhancer: evidence for dorsal corepressors

In Drosophila, the dorsal (dl) morphogen gradient initiates the differentiation of the embryonic mesoderm and neuroectoderm by activating the expression of regulatory genes (e.g. twist and snail) in a concentration-dependent manner. dl also functions as a repressor that establishes the dorsal epidermis and amnioserosa by restricting regulatory genes such as dpp and zen to dorsal regions of the embryo. The ability of dl to function as both an activator and repressor distinguishes it from the bicoid morphogen, which appears to function solely as an activator. In an effort to determine how dl functions as a repressor we have performed a detailed characterization of a zen silencer element, called the VRE, which mediates ventral repression in response to the dl gradient. A minimal 110 bp VRE sequence is identified, which is able to silence the ventral expression of a heterologous promoter. This sequence contains two dl binding sites as well as binding sites for additional nuclear factors present in early embryos. Mutations in the latter binding sites convert the minimal VRE into an enhancer, which mediates transcriptional activation in ventral regions in response to dl. These results suggest that dl is intrinsically an activator, but is converted into a potent silencer when it interacts with neighboring corepressors.

Modifying effect of 26-hydroxycholesterol on low-magnesium-induced atherosclerotic changes in the cultured human arterial smooth muscle cell

This study investigated the modifying effect of 26-hydroxycholesterol (26-OHC) on low-Mg(2+)-induced atherosclerotic changes in human arterial smooth muscle cells. Cells were exposed to a medium containing a concentration of 142, 332, 665 and 949 microM Mg2+ (as control) for the designed periods. Half the cells were simultaneously exposed to 10 micrograms/ml of 26-OHC. The results showed that the cytotoxicity of low Mg2+ and the stimulating effect of low Mg2+ on cytosolic free Ca2+ level and 45Ca2+ uptake were accentuated by 26 microns OHC. The significant increase of [3H]thymidine incorporation by Mg2+ level at and lower than 332 was, however, counteracted by 26-OHC. While an increased [3H]leucine incorporation occurred only at a level of 665 microM Mg2+, an additional increase of [3H]leucine incorporation also occurred at a level of 142 microM Mg2+ in the presence of 26-OHC. We suggest that 26-OHC could modify the atherogenic effect of low Mg2+.

Trichloroethanol potentiation of 5-hydroxytryptamine3 receptor-mediated ion current in nodose ganglion neurons from the adult rat

Trichloroethanol (TCEt) potentiated ion current mediated by 5-hydroxytryptamine (5-HT)3 receptors in isolated adult rat nodose ganglion neurons. The magnitude of potentiation of peak current amplitude increased with increasing TCEt concentrations from 0.5 to 5 mM. The rate of decay of current also increased as a function of TCEt concentration. Steady-state current was unaffected by TCEt at concentrations up to 10 mM. A high concentration of TCEt (25 mM) potentiated peak current but inhibited steady-state current. Potentiation appeared to involve an increase in agonist potency as the magnitude of potentiation of peak current decreased with increasing agonist concentration. Agonist application before TCEt treatment decreased the magnitude of potentiation elicited by 5 mM TCEt. These observations indicate that the potentiating action of TCEt arises from an increase in the efficacy with which 5-HT activates current. TCEt appears to facilitate transitions from closed to open states more readily than transitions from desensitized to open states. These observations are consistent with the hypothesis that 5-HT3 receptor function may contribute to the behavioral pharmacology of alcohols and related sedative/hypnotic agents.

Pharmacologic properties of KT2-962 (6-isopropyl-3-[4-(p- chlorobenzenesulfonylamino)-butyl]-azulene-1-sulfonic acid sodium salt); a new TXA2/prostaglandin endoperoxide receptor antagonist

Pharmacologic properties of KT2-962 (6-isopropyl-3-[4-(p-chlorobenzenesulfonylamino)butyl]-azulene+ ++-1-sulfonic acid sodium salt, KT) were studied in isolated rat aorta, rat tail artery, rabbit aorta, rabbit renal artery, and pig coronary artery. KT competitively inhibited the contractions induced by thromboxane A2 (TXA2) mimetic, U46619 (pA2 values 9.95, 8.85, 7.87, 8.49, and 9.12, respectively). KT also inhibited the contraction of rabbit aorta induced by prostaglandin2 alpha (PGF2 alpha, pA2 value 7.85) and the contraction of guinea pig ileum induced by LTD4 (pA2 value 5.48) but did not alter the contractions induced by norepinephrine (NE), Ca2+, serotonin, and histamine. KT did not alter the contractions of guinea pig ileum, which did not contract with U46619, induced by PGE2 and PGF2 alpha. KT inhibited the aggregations of rabbit platelets induced by U46619, arachidonic acid, and collagen (IC50 values 7.9, 140, and 16 microM, respectively) but not those induced by ADP. It also inhibited the specific binding of TXA2/PGH2 receptor antagonist, [3H]SQ29,548, to rabbit gel-filtered platelets with an IC50 value of 1.5 x 10(-8) M. In in vivo experiments with mice, oral administration of KT protected the U46619-induced sudden death with the minimum effective dose of 0.3 mg/kg and provided such protection for > 8 h at 1.0 mg/kg. These results indicate that KT is a new nonprostanoid type TXA2/PGH2 receptor antagonist that is orally effective and long acting.

[A comparative study of "angioblastic meningioma", hemangiopericytoma and cerebellar hemangioblastoma]

Forty-nine cases of the so-called "angioblastic meningioma", six cases of cerebellar hemangioblastoma, and four cases of soft tissue hemangiopericytoma were studied with HE, reticulin stainings, and immunohistochemical reaction with Vimentin, EMA, GFAP, S-100, and UEA-1 antibodies. The results showed that among the three subtypes of "angioblastic meningioma", namely, the hemangiomatous (H), the hemangioblastic (AB), and the hemangiopericytic (P) types, (1) type H belongs to true meningioma; (2) most of type P are almost identical with soft tissue hemangiopericytoma and different from true meningiomas, therefore belong to hemangiopericytoma arising from pericytes; however (3) some true meningiomas may appear as hemangiopericytoma histologically; (4) a few of AB are very similar to cerebellar hemangioblastoma and thus should be considered as supratentorial hemangioblastoma, while most of AB are still true meningiomas.

Factors (TAFs) required for activated transcription interact with TATA box-binding protein conserved core domain

TFIID is a multisubunit protein containing the TATA box-binding polypeptide (TBP) and associated factors (TFIID-TAFs) required for activated transcription by RNA polymerase II. TBPs from different eukaryotes contain a highly conserved carboxy-terminal domain and very divergent amino-terminal domains. Earlier studies proposed that the amino-terminal domains of metazoan TBPs are required for activated transcription. However, we report that a human TFIID complex containing an amino-terminal truncated TBP contains all the major TFIID-TAFs and supports in vitro transcriptional stimulation by different classes of activation domains and from a TATA-less promoter. Protein blotting experiments revealed direct interactions between the conserved domain of TBP and the two largest TAFs. The results suggest a model for the interaction of TFIID-TAFs with TBP.

Cytotoxicity of oxysterols on cultured smooth muscle cells from human umbilical arteries

The lethal effect of 25- and 26-hydroxycholesterol on smooth muscle cells derived from human umbilical arteries was investigated. The extent of cellular death corresponded with increasing oxysterol concentrations and incubation times. Incubation of the cells with 0.5, 2.5, or 10 micrograms/ml of 25- or 26-hydroxycholesterol revealed a proportionality between the degree of cellular death and oxysterol concentration over the 5 days of the experiment. Correlation coefficients among the degree of cellular death, the exposing period, and oxysterol concentration were significantly different (P < 0.05). However, none of these changes were noted in the smooth muscle cells cultured for 5 days in a medium containing the same concentration of cholesterol or 0.5% ethanol. An increase in the concentration of either serum or cholesterol in the culture medium did not significantly reduce the cytotoxicity of 2.5 micrograms/ml of 26-hydroxycholesterol. The results of this study suggest that oxysterols have an injurious effect on arterial cells, and that the injurious effect could not be altered by cholesterol, which was present at a serum concentration 12 times higher than that of oxysterols.

L-14 lectin recognition of laminin and its promotion of in vitro cell adhesion

The S-type lactose-binding lectins are found in a variety of animal tissues and their primary sequences are highly conserved between species. Little is known, however, about their functions and endogenous ligands. We report here our studies on the carbohydrate binding specificity of one S-type lectin designated L-14, using glycopeptides and glycoproteins from Chinese hamster ovary cells and mouse teratocarcinoma F9 cells. Our studies demonstrate that L-14 binds with high affinity to oligosaccharides containing multiple repeating units (approximately 4) of the disaccharide [3Gal beta 1-4GlcNAc beta 1]n or poly-N-acetyllactosamine (PL) sequence. Interestingly, terminal beta-galactosyl residues are not necessary for high affinity binding of long PL-containing oligosaccharides to L-14. To characterize the glycoprotein ligands for L-14, we applied total [3H]galactose-labeled glycoproteins from differentiated F9 cells to L-14-Sepharose. Laminin was one of the major glycoproteins in both the cells and the media bound by the lectin. The possible functional significance of this interaction is suggested by the fact that in the absence of Ca2+ L-14 can mediate the binding in vitro of both CHO and F9 cells to immobilized laminin. Taken together, these studies demonstrate that L-14 binds with high affinity to laminin and to relatively long PL chains and indicate that L-14 can promote cell adhesion to laminin.

Digital subtraction angiography in the diagnosis of congenital heart diseases: analysis of 60 cases

Ninety-one IVDSA and/or IADSA examinations with 192 injections were performed in 60 patients with congenital heart disease (CHD), including 31 anatomic anomalies. Axial projection was used in 23 patients. Analysis of the results of this series showed that accurate diagnosis by DSA confirmed by cardiac surgery together with definite diagnosis by DSA were obtained in 54 cases (90%). Two cases of nondiagnosis by DSA resulted from a suboptimal DSA method; four cases of partially accurate or mistaken diagnosis determined by cardiac surgery occurred because the axial view was not used and/or the anomalies were too small to be visualized by DSA. To increase the diagnostic accuracy of DSA in CHD, an optimal method of DSA must be selected according to the position of the anomaly and the hemodynamic data, and the axial view should be used to visualize the anomaly clearly in complex cases. In addition, DSA may fail to define a mild anomaly because of its lower spatial resolution.

Thrombomodulin as a marker of radiation-induced endothelial cell injury

Cultured confluent human umbilical vein endothelial cells were irradiated in vitro with 60Co gamma rays at doses from 0 to 50 Gy. After irradiation thrombomodulin was measured at different times over 6 days in the supernatants of endothelial cell culture medium, on the surface of the cells, and within the cells. At 24 h after irradiation, an increase in the release of thrombomodulin from irradiated endothelial cells and an increase in the number of molecules and the activity of thrombomodulin on the surface of the cells were observed; these reactions were dependent on radiation dose. The capacity of the cells to produce and release thrombomodulin was decreased from 2 to 6 days after exposure to 60Co gamma rays. Our data indicate that radiation can injure endothelial cells, and that thrombomodulin may be used as a marker of radiation-induced injury in endothelial cells. The interrelationship between the dysfunction of irradiated endothelial cells and the pathological mechanisms of acute radiation disease is also discussed.

Holo-TFIID supports transcriptional stimulation by diverse activators and from a TATA-less promoter

Transcription factor IID (TFIID) binds to TATA boxes, nucleating the assembly of initiation complexes containing several general transcription factors and RNA polymerase II. Recently, TFIID was shown to be a multisubunit complex containing a TATA box-binding polypeptide (TBP) and several tightly associated polypeptides (TAFs), which are required for transcriptional stimulation by activator proteins. Here, we report the development of a human cell line expressing an epitope-tagged TBP and the immunopurification of a native, high-molecular-weight form of TFIID that supports transcriptional stimulation by several different classes of activation domains. Recovery of basal and activated TFIID transcriptional specific activity was close to approximately 100%. Electrophoretic mobility-shift analysis demonstrated a single major DNA-protein complex. This holo-TFIID contains TAFs of approximately 250, 125, 95, 78, and 50 kD and sediments at 17S. Holo-TFIID produced an extended footprint over the adenovirus major late promoter TATA box and initiator sequence and supported transcriptional activation from a promoter lacking a TATA box. These results lead us to hypothesize that a single multisubunit TFIID protein supports transcriptional stimulation by diverse activation domains and from a TATA-less promoter.

Pre- and postoperative sequential study on the serum gastrin level in patients with lung cancer

Serial changes in serum gastrin level were detected by radioimmunoassay in 58 lung cancer patients before and after operation. In comparing these tests with those of 40 cases of noncancerous thoracic lesions and 151 normal adults, the serum gastrin from lung cancer patients is significantly higher than that of noncancerous thoracic lesions and normal individuals (P less than 0.01). The gastrin level is closely related to stage of cancer, size of primary tumor, presence of lymph node metastasis, and type of histological classification. The serum gastrin was found to decrease gradually after the removal of the tumor and to return to normal on the 14th postoperative day. Those patients whose serum gastrin level can return to normal on the 14th postoperative day will have a good prognosis; if not, their prognosis will be very poor. These results suggest that serum from patients with lung cancer contains a high concentration of gastrin that can help differentiate benign from malignant thoracic lesions and evaluate prognosis of patients with lung cancer. Therefore, the cause of high serum gastrin in patients with lung cancer is likely due to the gastrin-producing property of the lung cancer cells.

Individual dorsal morphogen binding sites mediate activation and repression in the Drosophila embryo

The dorsal (dl) morphogen gradient is responsible for initiating the differentiation of the mesoderm, neuroectoderm and dorsal ectoderm in the Drosophila embryo. dl encodes a sequence-specific DNA binding protein that belongs to the Rel family of transcription factors. Previous studies have shown that dl activates the mesoderm determinant twist (twi); here we use a combination of site-directed mutagenesis and P-transformation assays to demonstrate that it also functions as a direct transcriptional repressor of a second target gene, zerknüllt (zen). By exchanging dl binding sites between the promoters we show that activator sites from twi can mediate repression when placed in the context of the zen promoter, and that repressor sites from zen can mediate activation in the context of the twi promoter. This represents the first demonstration that common binding sites for any DNA binding protein can mediate both activation and repression in a developing embryo. Evidence is also presented that the affinities of dl binding sites are important for the efficiency of repression, but are not the sole determinants of the threshold response to the dl gradient.

[Experimental study of atherosclerosis and cholelithiasis with the same treatment. I. Effects of yiqi huoxue and shugan liqi agents in atherosclerosis of rabbit]

This paper reports the treatment with Yiqi Huoxue and Shugan Liqi agents in atherosclerosis of rabbit. The results suggested: 1. Both decoctions could reduce the cholesterol of hypercholesterolemia and improve the atherosclerosis, but the former was better than the latter. 2. Both decoctions could alter the components of bile lipids, but on the contrary, the latter was better than the former in reducing the formation of gallstones. 3. Both decoctions could decrease the plasma concentration of LPO and ratio of TXB2/6-K-PGF1 alpha, while increase the ratio of cAMP/cGMP in plasma. So, the different prescriptions of TCM affecting the same link of pathogenesis might play the role of "Different Treatments in Same Disease".

The diagnostic significance of gastrin measurement of bronchoalveolar lavage fluid for lung cancer

In this study, determination of gastrin concentration in bronchoalveolar lavage fluid and serum has been detected by radioimmunoassay in 30 cases of lung cancer and 24 cases of non-cancer pulmonary diseases. The results show that the gastrin concentration and its positive rate of lavage fluids from cancer lung are much higher than those from healthy lung and serum in lung cancer patients, and those from serum and both disease and healthy lung in non-cancer pulmonary disease patients (P less than 0.01). The gastrin ratio of lavage fluids from cancer lung to serum is also significantly higher than the ratio of lavage fluid from healthy lung to serum and all the ratios in the non-cancer pulmonary disease group. These results suggest that there is a high gastrin concentration in local tissue of lung cancer, which is signified by the high concentration of gastrin and its high positive rate in lavage fluids from the lung with cancer. Therefore, the gastrin determination in lavage fluids and gastrin ratio of lavage fluids to serum are more reliable in the differential diagnosis of benign from malignant pulmonary diseases than gastrin determination of serum alone.