Synthesis and properties of poly(ethylene glycol) macromer/beta-chitosan hydrogels

Semi-interpenetrating polymer network (semi-IPN) hydrogels composed of beta-chitosan and poly(ethylene glycol) diacrylate macromer (PEGM) were synthesized and characterized for the application as potential biomedical materials. The mixture of PEGM and beta-chitosan, dissolved in water including a small amount of acetic acid, was cast to prepare hydrogel films, followed by a subsequent crosslinking with 2,2-dimethoxy-2-phenylacetophenone as a non-toxic photoinitiator by ultraviolet irradiation. Photocrosslinked hydrogels exhibited relatively high equilibrium water content in the range 77-83% which is mainly attributed to the free water content rather than to the bound water, hydrogen bonded with components in semi-IPN hydrogels. The crystallinity, thermal properties and mechanical properties of semi-IPN hydrogels were studied. All the photocrosslinked hydrogels revealed a remarkable decrease in crystallinity. The glass transition temperatures, Tg, of crosslinked PEGM segment in semi-IPNs increased compared with poly(ethylene glycol) itself. However, with increasing beta-chitosan content their Tg decreased owing to the higher degree of crosslinking. The tensile strengths of semi-IPNs in dry state were rather high, but those of hydrogels in wet state decreased drastically.

Effect of the aqueous extract of Aquilaria agallocha stems on the immediate hypersensitivity reactions

We investigated the effects of the aqueous extract of Aquilaria agallocha Roxb. (Thymelaeaceae) on the immediate hypersensitivity reactions. The aqueous extract of Aquilaria agallocha stems showed inhibitory effects on passive cutaneous anaphylaxis, anaphylaxis induced by compound 48/80, and histamine release from rat peritoneal mast cells (RPMC). The morphological examination also clearly showed that the extract prevented the degranulation of RPMC in rats. The level of compound 48/80-induced intracellular cAMP in RPMC, when the extract was added, significantly increased about 8-fold at 10 s compared with that of basal cells. These results suggest that the aqueous extract of Aquilaria agallocha stems inhibits the immediate hypersensitivity reaction by inhibition of histamine release from mast cells.

In vitro blood compatibility of functional group-grafted and heparin-immobilized polyurethanes prepared by plasma glow discharge

Blood compatibilities of functional group-grafted and heparin-immobilized polyurethanes (PUs) were investigated using in vitro thrombus formation, plasma recalcification time (PRT), activated partial thromboplastin time (APTT), platelet adhesion and activation, and peripheral blood mononuclear cell (PBMC) activation. In the experiment with plasma proteins, PRT was shortened on amine group-grafted PU (PU-NH2) but prolonged on heparin-immobilized polyurethane (PU-Hep) when compared to PU control. APTT was significantly prolonged on PU-Hep, suggesting the binding of immobilized heparin to antithrombin III. The percentage of platelet adhesion was slightly increased by the introduction of functional groups such as carboxylic acid and primary amine on PU surfaces, but significantly decreased by the immobilization of heparin on the same substrate. The percentage of serotonin released from platelets adhered on surface-modified PUs was increased with increase of platelet adhesion. In the PBMC experiment, cells adhered less on heparin-immobilized PUs than on functional group-grafted PUs, and the production levels of tumour necrosis factor mRNAs from the cells stimulated by heparin-immobilized PU (PU-N-Hep) were smaller than those by the other substrates.

Losartan attenuates myocardial ischemia-induced ventricular arrythmias and reperfusion injury in spontaneously hypertensive rats

To assess the efficacy of losartan (2-n-butyl-4-chloro-5-hydroxymethyl-1-[(2'-(1H-tetrazol-5-yl)biphe nyl-4-yl)methyl]imidazole, potassium salt), an angiotensin II receptor antagonist, on acute myocardial ischemia, 36 four-month-old spontaneously hypertensive rats were used. The animals underwent 45 min of left coronary artery occlusion and 1 h of reperfusion and were randomly assigned to control and losartan-treated groups (2, 5, and 10 mg/kg, intravenously). Losartan was administered 15 min before ischemia. Electrocardiograms (lead II) were monitored continuously throughout the experiment. To assess the anti-infarct effect of losartan, the area at risk was determined by methylene blue dye and the infarct size was determined by nitroblue tetrazolium chloride staining. The areas of risk and infarct were measured by computerized planimetry. Results demonstrated that the low and intermediate doses (2 and 5 mg/kg) of losartan significantly decreased the incidence of ventricular fibrillation and mortality during the ischemic period induced by left coronary artery occlusion. However, a significant reduction in infarct size, calculated as a percentage of the area at risk, was noted in all three losartan-treated groups (control: 41.5% +/- 5.2%, losartan, 2 mg/kg: 11.2% +/- 5.8%, 5 mg/kg: 8.5% +/- 2.7% and 10 mg/kg: 13.7% +/- 1.6%). The results suggest that losartan may be useful in the treatment of ventricular arrhythmias induced by acute myocardial infarction and attenuation of reperfusion injury in hypertension.

Twist-mediated activation of the NK-4 homeobox gene in the visceral mesoderm of Drosophila requires two distinct clusters of E-box regulatory elements

NK-4, also called msh2 and tinman, encodes a homeodomain transcription factor that is required for the development of the dorsal mesoderm and its derivatives in the Drosophila embryo. Genetic analyses indicate that NK-4 resides downstream of the mesodermal determinant twist, which encodes a basic helix-loop-helix-type transcription factor. However, the regulation of NK-4 by twist remains poorly understood. Using expression assays in cultured cells and transgenic flies, we show that two distinct clusters of E-box regulatory sequences, present upstream of the NK-4 gene, mediate NK-4 expression in the visceral mesoderm. These elements are conserved between the Drosophila melanogaster and Drosophila virilis NK-4 genes and serve as binding sites for Twist (E1 cluster) and NK-4 (E2 cluster) proteins. In cultured cells, Twist and NK-4 binding results in activation of NK-4 gene expression. In transgenic animals, the E1 and E2 clusters are functionally connected, and both elements are required for NK-4 activation in cells of the visceral mesoderm and also for NK-4 repression in cells of the somatic musculature. These results demonstrate that NK-4 is a direct transcriptional target for Twist and its own gene product in visceral mesodermal cells, supporting the idea that twist and NK-4 function in the subdivision of the mesoderm during Drosophila embryogenesis.

Suxamethonium and cardiac arrest

We report a case of cardiac arrest due to hyperkalaemia following administration of suxamethonium during a procedure to facilitate a change of endotracheal tube in a septic patient. The cause of this rare but fatal complication is briefly described and discussed. In view of this, suxamethonium should be used with great caution in patients with burns and other forms of physical injury, in a number of nervous system disorders, and in critically ill patients requiring prolonged ITU care.

Anti-insect toxin 5 (AaIT5) from Androctonus australis

An insect-selective scorpion toxin (AaIT5) was purified from the venom of the North African scorpion Androctonus australis, and its amino acid sequence was determined by a combination of automated Edman degradation, electrospray-ionization mass spectrometry, and sequence alignment. This insect toxin is very potent against the tobacco budworm, Heliothis virescens (100% lethal dose < 1.8 microg/100 mg body mass) and shows a distinct insect specificity and various symptoms. It is not toxic to mice after subcutaneous injection. The molecular mass of this toxin is 6882 Da and the amino acid sequence is similar to those of Androctonus australis anti-insect toxin 4 (AaIT4), Leiurus quinquestriatus depressant anti-insect toxins (LqhIT2, LqqIT2), and Buthotus judaicus depressant anti-insect toxin (BjIT2).

TNF mediates lung leak, but not neutrophil accumulation, in lungs of rats given IL-1 intratracheally

Interleukin-1 (IL-1) is increased in lung lavages obtained from patients with acute respiratory distress syndrome, and administering IL-1 intratracheally to rats causes an acute, neutrophil-dependent, oxidative lung leak. We found that rats given IL-1 intratracheally had increased lung lavage fluid tumor necrosis factor (TNF) levels, and that rats treated with TNF binding protein (TNFbp) intravenously did not develop the increased lung leak that occurs after administration of IL-1 intratracheally. In contrast, rats given IL-1 intratracheally and TNFbp intravenously had the same elevations in lung lavage neutrophil accumulation and lung lavage cytokine-induced neutrophil chemoattractant levels as rats given IL-1 intratracheally. Our results show that TNFbp decreases neutrophil-mediated lung leak, but not lung neutrophil accumulation, after administration of IL-1 intratracheally in rats.

Synergistic transactivation of HNF-1alpha, HNF-3, and NF-I contributes to the activation of the liver-specific protein C gene

We have previously characterized the functional cis elements of the protein C promoter. One hepatocyte nuclear factor-1 (HNF-1) site, three HNF-3 sites, and at least two NF-I sites have been identified within the 140-bp basal transcriptional unit of this promoter. Here we present evidence that either HNF-1alpha or HNF-3 can cooperate with each other in binding to their cis elements. The results from the co-transfection assays in HeLa cells showed a novel synergistic transactivation between HNF-1alpha and HNF-3. Our data further indicate that the unique overlapping of the HNF-3 sites, the specific spatial relationship of the sites, and the co-activator C/EBP all contributed to the synergistic interaction. Although NF-I itself has a weak transactivating effect, it apparently coordinates the transactivation complex formation. NF-I can synergistically enhance the transactivation of HNF-1alpha or HNF-3. Taken together, the combinatorial interplay of HNF-1alpha, HNF-3, and NF-I make a significant contribution to the activation of the liver-specific protein C gene.

Mepacrine decreases lung leak in rats given interleukin-1 intratracheally

We hypothesized that phospholipase A2 (PLA2) metabolites contribute to the acute, neutrophil-dependent, edematous lung leak that develops after administration of interleukin-1 (IL-1) intratracheally to rats and tested this premise by using mepacrine to inhibit PLA2 activity in vivo. We found that lung PLA2 activity, lung lavage phospholipid content, lung leak index, lung weight gain, and lung lavage protein concentrations were increased in rats given IL-1 intratracheally compared with sham-treated control rats. By comparison, lungs of mecaprine and IL-1-treated rats had decreased PLA2 activity, lavage phospholipid content, leak, weight gain, and lavage protein increases compared with rats given IL-1 intratracheally. Mepacrine treatment also decreased lung neutrophil accumulation, but not lung lavage cytokine-induced neutrophil chemoattractant (CINC) levels, in rats given IL-1 intratracheally. In parallel experiments, mepacrine treatment reduced the adhesion of human neutrophils to IL-1-treated human umbilical vein endothelial cells in vitro. Our results indicate that PLA2 activity participates in the lung neutrophil retention and pulmonary vascular leak that develops in rats given IL-1 intratracheally.

The Brevibacterium albidum gene encoding the arginine tRNACCG complements the growth defect of an Escherichia coli strain carrying a thermosensitive mutation in the rnpA gene at the nonpermissive temperature

The Escherichia coli rnpA gene encodes C5 protein, the protein component of RNase P. The rnpA49 mutation renders the C5 protein thermosensitive, which results in thermosensitivity of RNase P function. The chromosomal DNA region from Brevibacterium albidum that complements the rnpA49 mutation was analysed. The gene capable of complementing the growth defect of an rnpA49 mutant strain at nonpermissive temperature was identified as the gene for an arginine tRNA with anticodon CCG by a deletion analysis combined with complementation assays. Transcription of the arginine tRNA gene carried on a multicopy plasmid was correlated with the complementation of the rnpA49 mutation, indicating that the gene product is indeed responsible for complementation of the rnpA49 mutation.

FMR1 enhancer is regulated by cAMP through a cAMP-responsive element

FMR1 (Fra X Mental Retardation 1), a gene of unknown function, is responsible for an important hereditary mental retardation, the fragile X syndrome. In this study, a 22-bp enhancer (methylation sensitive element, MSE) in the FMR1 promoter was defined by DNase I footprinting assay, and the binding of this element by nuclear factor was prevented by DNA CpG methylation. A cAMP-responsive element (CRE)-like sequence and a myc-binding sequence in MSE were identified. In the transfection assay, MSE demonstrated a strong, methylation-sensitive enhancer activity. MSE could be bound by recombinant CRE-binding protein (CREB), and its activity was stimulated by CREB in a co-transfection assay. In PC12 cells, forskolin elevated MSE activity several fold, and this induction was abolished in CRE mutants. The involvement of cAMP in the expression of FMR1 should be a clue to both the function of FMR1 and the pathogenesis of fragile X syndrome.

Expression of mast-cell-specific proteases in tissues of mice studied by in situ hybridization

The protease mRNA expression phenotype of individual mast cells was studied by in situ hybridization. Mouse mast cell protease (MMCP)-2 mRNA was expressed by mast cells located in the mucosa of the stomach of WB(-)+/+ and (WB x C57BL/6)F1(-)+/+ (hereafter WBB6F1(-)+/+) mice but not by mast cells in the same tissue of C57BL/ 6(-)+/+ mice. Even in the stomach of WBB6F1(-)+/+ mice, mast cells located in the muscularis propria did not express MMCP-2 mRNA. The mRNAs of MMCP-4 and mouse mast cell carboxypeptidase A were not expressed by mast cells in the stomach mucosa of untreated WBB6F1(-)+/+ mice but were expressed after the infection of Strongyloides venezuelensis. We examined whether MMCP-2 mRNA expression varied by changing environments of mast cells. Cultured mast cells of WBB6F1(-)+/+ mice that expressed MMCP-2 mRNA were transplanted into the stomach wall of genetically mast-cell-deficient WBB6F1(-)W/Wv mice. Mast cells that appeared in the mucosa expressed the MMCP-2 mRNA, but mast cells that appeared in the muscularis propria did not, indicating the adaptation of cultured mast cells into a new environment. In contrast to cultured mast cells, peritoneal mast cells of WBB6F1(-)+/+ mice that expressed MMCP-2 mRNA as well did not adapt to the muscularis propria of WBB6F(1)-W/Wv mice. The MMCP-2 mRNA remained to be expressed after the settlement in either the mucosa or the muscularis propria. Furthermore, the peritoneal mast cells did not change the MMCP-4 and MMCP-6 mRNA expression phenotype after the settlement in either the mucosa or the muscularis propria of WBB6F(1)-W/Wv mice. The present result indicated that both intracellular factors such as strain specificity and source of mast cells and extracellular factors such as tissue specificity and helminth infection influenced the protease expression phenotypes.

Hyperactivation of the silencing proteins, Sir2p and Sir3p, causes chromosome loss

The SIRgene products maintain transcriptional repression at the silent mating type loci and telomeres in Saccharomyces cerevisiae, although no enzymatic or structural activity has been assigned to any of the Sir proteins nor has the role of any of these proteins in transcriptional silencing been clearly defined. We have investigated the functions and interactions of the Sir2, Sir3, and Sir4 proteins by overexpressing them in yeast cells. We find that Sir2p and Sir3p are toxic when overexpressed, while high Sir4p levels have no toxic effect. Epistasis experiments indicate that Sir2p-induced toxicity is diminished in strains lacking the SIR3 gene, while both Sir2p and Sir4p are required for Sir3p to manifest its full toxic effect. In addition, the effects of Sir2 or Sir3 overexpression are exacerbated by specific mutations in the N-terminus of the histone H4 gene. These results are consistent with a model in which Sir2p, Sir3p and Sir4p function as a complex and interact with histones to modify chromatin structure. We find no evidence that toxicity from high levels of the Sir proteins results from widespread repression of transcription. Instead, we find that high levels of Sir2p and/or Sir3p cause a profound decrease in chromosome stability. These results can be appreciated in the context of the effects of Sir2p in histone acetylation and of chromatin structure on chromosome stability.

D-mef2 is a target for Tinman activation during Drosophila heart development

The NK-type homeobox gene tinman and the MADS box gene D-mef2 encode transcription factors required for the development and differentiation of the Drosophila heart, and closely related genes regulate cardiogenesis in vertebrates. Genetic analyses indicate that tinman and D-mef2 act at early and late steps, respectively, in the cardiogenic lineage. However, it is unknown whether regulatory interactions exist between these developmental control genes. We show that D-mef2 expression in the developing Drosophila heart requires a novel upstream enhancer containing two Tinman binding sites, both of which are essential for enhancer function in cardiac muscle cells. Transcriptional activity of this cardiac enhancer is dependent on tinman function, and ectopic Tinman expression activates the enhancer outside the cardiac lineage. These results define the only known in vivo target for transcriptional activation by Tinman and demonstrate that D-mef2 lies directly downstream of tinman in the genetic cascade controlling heart formation in Drosophila.

Mutations in the matrix protein of human immunodeficiency virus type 1 inhibit surface expression and virion incorporation of viral envelope glycoproteins in CD4+ T lymphocytes

Highly conserved amino acids in the second helix structure of the human immunodeficiency virus type 1 (HIV-1) MA protein were identified to be critical for the incorporation of viral Env proteins into HIV-1 virions from transfected COS-7 cells. The effects of these MA mutations on viral replication in the HIV-1 natural target cells, CD4+ T lymphocytes, were evaluated by using a newly developed system. In CD4+ T lymphocytes, mutations in the MA domain of HIV-1 Gag also inhibited the incorporation of viral Env proteins into mature HIV-1 virions. Furthermore, mutations in the MA domain of HIV-1 Gag reduced surface expression of viral Env proteins in CD4+ T lymphocytes. The synthesis of gp160 and cleavage of gp160 to gp120 were not significantly affected by MA mutations. On the other hand, the stability of gp120 in MA mutant-infected cells was significantly reduced compared to that in the parental wild-type virus-infected cells. These results suggest that functional interaction between HIV-1 Gag and Env proteins is not only critical for efficient incorporation of Env proteins into mature virions but also important for proper intracellular transport and stable surface expression of viral Env proteins in infected CD4+ T lymphocytes. A single amino acid substitution in MA abolished virus infectivity in dividing CD4+ T lymphocytes without significantly affecting virus assembly, virus release, or incorporation of Gag-Pol and Env proteins, suggesting that in addition to its functional role in virus assembly, the MA protein of HIV-1 also plays an important role in other steps of virus replication.

Treatment of chronic hepatitis C with interferon alfa-n3: a multicenter, randomized, open-label trial

We studied the antiviral effectiveness and safety of interferon alfa-n3, a natural alpha interferon which contains multiple interferon species, in the treatment of previously untreated patients with chronic hepatitis C. Seventy-seven patients were randomized to receive either 1.0, 2.5, 5.0, or 10.0 million units (MU) of interferon alfa-n3 three times a week for 24 weeks and were then followed for an additional 24 weeks. At the end of therapy, 67% of patients in the 10 MU group normalized serum alanine transaminase (ALT) levels and 59% had no hepatitis C virus (HCV) RNA detected by polymerase chain reaction. At the end of the follow-up period, 44% of patients in the 10 MU group maintained normal ALT, and 24% had nondetectable HCV RNA. Lower doses were much less effective. Interferon alfa-n3 was well tolerated and no patient developed neutralizing anti-interferon antibodies during or after the treatment period. Interferon alfa-n3 appears to be effective against hepatitis C virus and deserves further study in larger randomized controlled trials.

Purification, characterization, gene cloning, and expression of Saccharomyces cerevisiae redoxyendonuclease, a homolog of Escherichia coli endonuclease III

Saccharomyces cerevisiae redoxyendonuclease (Scr), a homolog of Escherichia coli endonuclease III, was purified from yeast deficient in the major apurinic/apyrimidinic endonuclease, Apnl. Studies of this highly purified preparation of Scr have revealed a number of similarities between this protein and endonuclease III as well as provided further evidence for a common mechanism of action for this class of DNA glycosylase/AP lyases. We have employed a sensitive and specific assay for Scr which utilizes oligonucleotide substrates containing a single 5,6-dihydrouracil base lesion or an abasic site. These substrates were utilized to investigate the mode of action of Scr on damaged DNA and to compare the kinetic properties of the yeast enzyme with its E. coli counterpart. Furthermore, we have identified two distinct genes, SCR1 and SCR2, which encode highly homologous proteins with similar activities in yeast. Analysis of the deduced amino acid sequences of SCR1 and SCR2 suggests that S. cerevisiae possesses two similar enzymes encoded on separate chromosomes: one which bears an Fe-S binding motif, while the other does not. The potential biological roles of these two forms of Scr are discussed.

Lisofylline prevents leak, but not neutrophil accumulation, in lungs of rats given IL-1 intratracheally

Interleukin-1 (IL-1) is increased in lung lavages from patients with the acute respiratory distress syndrome, and administering IL-1 intratracheally causes neutrophil accumulation and a neutrophil-dependent oxidative leak in lungs of rats. In the present study, we found that rats pretreated intraperitoneally with lisofylline [(R)-1-(5-hydroxyhexyl)-3, 7-dimethylxanthine (LSF)], an inhibitor of lysophosphatidic acid acyl transferase, which reduces the production of unsaturated phosphatidic acid species, did not develop the lung leak or the related ultrastructural abnormalities that occur after intratracheal administration of IL-1. However, rats pretreated with LSF and then given IL-1 intratracheally did develop the same elevations of lung lavage cytokine-induced neutrophil chemoattractant (CINC) levels and the same increased numbers of lung lavage neutrophils as rats given IL-1 intratracheally. Lungs of rats given IL-1 intratracheally also had increased unsaturated phosphatidic acid and free acyl (linoleate, linolenate) concentrations compared with untreated rats, and these lipid responses were prevented by pretreatment of LSF. Our results reveal that LSF decreases lung leak and lung lipid alterations without decreasing neutrophil accumulation or lung lavage CINC increases in rats given IL-1 intratracheally.

Effects of Poncirus trifoliata on type I hypersensitivity reaction

A study was carried out to examine the effect of an aqueous extract from immature fruit of Poncirus trifoliata L. (Rutaceae) (PTIFE) on the type I hypersensitivity reaction. Forty-eight hour PCA (passive cutaneous anaphylaxis) in rats was significantly inhibited by the oral administration of PTIFE (200 mg/kg). It also inhibited histamine release from rat peritoneal mast cells (RPMC) induced by mouse anti-dinitrophenyl (DNP)-IgE and dinitrophenyl-human serum albumin (DNP-HSA). These results suggest that PTIFE has anti-allergic action against the type I hypersensitivity reaction.

Mechanism of inhibition of platelet aggregation by rutaecarpine, an alkaloid isolated from Evodia rutaecarpa

In this study, rutaecarpine was tested for its antiplatelet activities in human platelet-rich plasma. In human platelet-rich plasma, rutaecarpine (40-200 microM) inhibited aggregation stimulated by a variety of agonists (i.e., collagen, ADP, adrenaline and arachidonic acid). The antiplatelet activity of rutaecarpine (120 microM) was not significantly attenuated by pretreatment with the nitric oxide synthase inhibitor N(G)-mono-methyl-L-arginine (L-NMMA) (100 microM) or N(G)-nitro-L-arginine methyl ester (L-NAME) (200 microM) and with the guanylyl cyclase inhibitor methylene blue (100 microM). In addition, rutaecarpine (40-200 microM) did not significantly affect cyclic AMP and cyclic GMP levels in human washed platelets, whereas it significantly inhibited thromboxane B2 formation stimulated by collagen (10 microg/ml) and thrombin (0.1 U/ml). Furthermore, rutaecarpine (40-200 microM) inhibited [3H]inositol monophosphate formation stimulated by collagen and thrombin in [3H]myoinositol-loaded platelets. It is concluded that the antiplatelet effects of rutaecarpine are due to inhibition of thromboxane formation and phosphoinositide breakdown.

Identification of phosphorylation sites in keratinocyte transglutaminase

Phosphorylation of keratinocyte transglutaminase occurs in its N-terminal extension and is stimulated several-fold by the protein kinase C agonist phorbol myristate acetate. In the present work, this stimulation was prevented by simultaneous treatment of the cells with the protein kinase C-selective inhibitor GF109203X. In contrast, phosphorylation occurring in the absence of phorbol ester was essentially unaffected by GF109203X, although it was decreased dramatically by the non-selective kinase inhibitor staurosporine. Four serine residues that are subject to phosphorylation have been identified by sequencing of radioactive tryptic peptides. Serines at positions 24 and 92, each containing 2-8% of the total radioactivity with or without phorbol ester stimulation, were minor sites of phosphorylation. Serine-82 was by far the dominant site of phosphorylation in the absence of phorbol ester treatment, and was also the major site in its presence. Serine-85 was phosphorylated to a high degree in the presence but not in the absence of phorbol ester stimulation. Thus the data indicate the influence of at least two different kinase activities in transglutaminase phosphorylation.

Antianaphylactic activity of Poncirus trifoliata fruit extract

The effect of an aqueous extract of Poncirus trifoliata (L.) Raf. (Rutaceae) fruits (PTFE) on compound 48/80-induced mortality associated with anaphylaxis was studied in rats. PTFE inhibited compound 48/80-induced anaphylaxis 100% with a dose of 1.6 mg/g body weight (BW) 1 h before or 5 min after injection of compound 48/80. PTFE inhibited compound 48/80-induced anaphylaxis almost 100% with doses above 0.4 mg/g BW intraperitoneally administered. PTFE (1-1000 micrograms/ml) also dose-dependently inhibited the histamine release induced by compound 48/80 (5 micrograms/ml) in rat peritoneal mast cells. The level of cAMP in peritoneal mast cells, when PTFE was added, increased transiently, and significantly increased 53-fold at 10 s compared with that of basal cells. Moreover, PTFE inhibited intracellular calcium release induced by compound 48/80. These results suggest that PTFE has antianaphylactic activity by stabilizing the peritoneal mast cell membrane.

Characterization of human protein C gene promoter: insights from natural human mutants

Human protein C is a liver-produced plasma anticoagulant. Four heterozygous point mutations located in the promoter region have been identified in families with type I protein C deficiency and recurrent venous thrombosis. However, detailed analysis of regulatory elements and their interacting factors remains to be undertaken. This report presents results of biochemical and functional characterizations of several cis-elements located in the 5'-upstream regulatory region and the trans-acting factors that interact with them. A cloned DNA fragment from nucleotides (nt) -418 to +45 could confer tissue specificity, whereas nt -88 to +45 was sufficient for basal promoter activity of protein C gene. Five cis-elements corresponding to HNF-1, HNF-3, and NF-I/CTF binding sites have been identified. Four heterozygous mutations have been shown to disrupt HNF-3 [mutants of A(-32)G and T(-27)A] and HNF-1 [T(-14)C and C(-10)T] binding. Mutation in the NF-I-binding site also significantly impairs the promoter activity. Viewed as a whole, these results indicate that HNF-1, HNF-3, and NF-I/CTF play critical roles in transcriptional regulation of the protein C gene.

Spontaneous duodenal perforation in neonates: a case report and review of literature

Although duodenal perforation in neonates is an extremely rare entity, it should be suspected in any case with signs of viscus perforation. If found in the absence of possible causes, duodenal perforation is considered to be spontaneous. It is believed to be of multifactorial origin. Once found primary closure with or without omental patching is the treatment of choice. In this article we describe one case of spontaneous perforation and analyze the possible causes.

Transcriptional induction of the alpha-1 acid glycoprotein (AGP) gene by synergistic interaction of two alternative activator forms of AGP/enhancer-binding protein (C/EBP beta) and NF-kappaB or Nopp140

Alpha-1 acid glycoprotein/enhancer-binding protein (AGP/EBP) (C/EBPbeta), a member of the C/EBP family, is one of the key transcription factors responsible for the induction of a wide array of genes, some of which are expressed during the acute-phase response. Both activator and repressor were shown to be encoded by the intronless agp/ebp or its rat and human homologs, which contain a common bZIP domain at their C-terminal regions. Expression of the AGP gene (agp) is regulated by AGP/EBP in liver during the acute-phase response. However, the molecular mechanism for this regulation is poorly understood. The experiments reported here demonstrate that two activator forms of AGP/EBP, one of which has an additional 21 amino acids at its N-terminal region, are expressed in liver as well as in a number of cell lines. We have also demonstrated that NF-kappaB and a phosphoprotein of 140 kDa, Nopp140, interact with different AGP/EBP activators synergistically, which results in induction of the agp gene in an AGP/EBP-binding-motif-dependent manner. Furthermore, extracellular stimuli that are known to be NF-kappaB inducers can selectively activate the agp gene by cooperating with one of the two activator forms of AGP/EBP. The physiological significance of differential regulation for the function of two activator forms of AGP/EBP through selective interaction with different transcription factors is discussed.

Inhibition of histamine synthesis by glycyrrhetinic acid in mast cells cocultured with Swiss 3T3 fibroblasts

The effect of glycyrrhetinic acid (18-O-beta-glycyrrhetinic acid, GA) on histamine metabolism was investigated in cultured mast cells (CMCs) cocultured with Swiss 3T3 fibroblasts. GA strongly inhibited histamine synthesis in the cocultured CMCs. Since 50 microM GA inhibited about 80% of histidine decarboxylase (HDC) activity, the inhibitory activity of GA for histamine synthesis was considered to be derived from the inhibition of HDC activity. The number of berberine-sulfate-positive cells also decreased in the presence of GA, which indicated that maturation of CMCs was inhibited by GA. Furthermore, we examined the effect of GA on the mRNA expression of novel protein kinase C delta (nPKC delta), a major isoform of CMCs, by northern blot analysis. The expression of nPKC delta mRNA in the presence of GA was significantly lower than in the absence of GA. These results suggest the possibility that the inhibition of histamine synthesis by GA is regulated by nPKC delta.

Hyperplasia of thymic gland

Hyperplasia of the thymus is the most common anterior mediastinal mass in infants. It is however exceedingly difficult to evaluate by the weight of the gland as it continues to grow after birth until puberty and thereafter undergoes progressive atrophy. It normally maintains most of the radiographic characteristics of the normal thymus. Massive thymic hyperplasia, a rare variant of true thymic hyperplasia is extremely rare during the first two decades of life and clinically can cause mediastinal compression or acute and recurrent pulmonary infection. Two such cases are reported and the clinico-pathology is briefly described and discussed.

Preparation and surface characterization of functional group-grafted and heparin-immobilized polyurethanes by plasma glow discharge

Functional group-grafted polyurethanes were prepared by oxygen plasma discharge treatment, followed by graft polymerization of 1-acryloylbenzotriazole (AB) and a subsequent substitution reaction of AB with sodium hydroxide and ethylene diamine. The primary amine or carboxylic acid groups grafted on the surfaces were coupled with heparin using water-soluble carbodiimide. The modified surfaces were characterized by measuring the water contact angle, electron spectroscopy for chemical analysis and attenuated total reflection Fourier-transform infrared spectroscopy. The amount of heparin covalently immobilized on the primary amine- and carboxylic acid group-grafted polyurethanes were 2.0 and 1.4 micrograms cm-2, respectively, as determined by the toluidine blue method. The water contact angle of the polyurethanes was decreased by AB grafting, and further decreased by the introduction of functional groups such as carboxylic acid and primary amine and immobilization of heparin, showing increased hydrophilicity of the modified surfaces. Heparin was almost not released from the immobilized surfaces in the physiological solution for 100 h, indicating good stability of immobilized heparin.

Major causes of diabetic death at one hospital

Death certificates filed between 1987 and 1990 at the Kaohsiung Medical College Hospital (KMCH) were reviewed to investigate causes of diabetic death. During this period, 1,383 patients expired at KMCH, of which 151 had diabetes mellitus. The major causes of death in these 151 diabetic patients were infection in 25.8%, cardiovascular disease in 18.5%, cerebrovascular disease in 11.3%, uremia in 8.6% and diabetic ketoacidosis in 1.3%, while diabetes was reported as the contributory or underlying cause of death. Malignancy in 12.0%, liver disease in 5.3%, trauma in 1.3% and upper gastroenteral bleeding in 0.7%, likewise, were among the leading causes of death irrespective of underlying diabetes. However, cause of death in 15.2% of these diabetic patients was undetermined. Our analysis revealed that infection and cardiocerebrovascular disease were the leading problems contributing to diabetic death. Therefore, reducing the risk of infection by strict glycemic control, intensive medical intervention in infection and the proper prevention of diabetic angiopathy-related risk factors and complications are imperative for the reduction of diabetic mortality in our patients.

Early experience of video-assisted thoracoscopic surgery

Consecutive 25 patients (M/F:18/7) underwent video-assisted thoracoscopic surgery (VATS) for various chest illnesses. These included nine cases of pneumothorax, three cases of pericardial effusion, three cases of pleural effusion, four cases of lung lesion requiring either incisional or excisional biopsy, two cases of empyema, one case of traumatic haemothorax, and three cases of mediastinal lesion. The mean age was 36.2 years (range 19-78 years). A total of forty-three procedures were performed. The mean durations of intrapleural chest-tube requirement and hospitalisation following VATS alone were 4.5 days (range: 0-13 days) and 8.3 days (range: 2-25 days) respectively. No intraoperative complication and VATS procedure-related mortality reported. Apart from simple analgesics such as paracetamol or tramadolol, no opiate analgesia was given to patients undergoing only VATS. The results support that VATS is a safe and effective procedure in the management of pulmonary, mediastinal, pericardial and pleural diseases and the treatment of persistent and recurrent spontaneous pneumothorax.

Effects of DC-015, a novel potent and selective alpha 1-adrenoceptor antagonist on plasma lipid and vascular reactivity in hyperlipidaemic rats

1. The effects of DC-015, a newly synthesized quinazoline derivative, on plasma lipids, lipoprotein levels and vascular reactivity were investigated in Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). 2. The hypotensive effect of DC-015 was compared with prazosin in SHR. Intravenous administration of DC-015 and prazosin (both at 0.01, 0.05 and 0.1 mg/kg) induced dose-dependent reductions in mean arterial pressure (MAP) which reached a maximal effect 5 min after injection and persisted over 2 h in SHR. DC-015 decreased MAP with equal efficiency compared with prazosin. 3. The plasma levels of total cholesterol (CE), low-density lipoprotein (LDL)-CE and total triglyceride (TG) were markedly increased and the levels of high-density lipoprotein (HDL)-CE were markedly decreased in both high fat-high cholesterol (HF-HC) diet fed WKY and SHR. 4. In HF-HC diet fed WKY and SHR, the total plasma CE, LDL-CE and total plasma TG were significantly reduced after oral administration of DC-015 (1 mg/kg, twice a day) for 4 weeks. Furthermore, DC-015 therapy was associated with increased HDL-CE levels and thus the ratio of total CE to HDL-CE was improved. The antihyperlipidaemic effect of prazosin was less than that of DC-015. 5. Significantly attenuated median effective concentration (EC50) values and augmented maximal responses for phenylephrine-induced contraction of aortic rings were observed in HF-HC diet fed WKY and SHR. Endothelium-dependent relaxation to acetylcholine was impaired while endothelium-independent relaxation to nitroglycerin was well preserved. 6. Oral administration of DC-015 (1 mg/kg, twice a day) for 4 weeks significantly augmented EC50 values and attenuated maximal responses for phenylephrine-induced contraction of aortic rings in HF-HC diet fed WKY and SHR. Prazosin (1 mg/kg, twice a day) showed a lesser extent of efficiency than DC-015 at normalization of vasorelaxation in HF-HC diet fed WKY and SHR. 7. It is concluded that DC-015, a potent antihypertensive agent, may have additional advantage in also reducing hyperlipidaemia.

Serum hepatitis C RNA titers after liver transplantation are not correlated with immunosuppression or hepatitis

The degree to which immunosuppression and/or rejection influences recurrent hepatitis C (HCV) after liver transplantation (LT) for end-stage HCV cirrhosis remains poorly defined. We quantified serum HCV-RNA in 84 serum samples from 28 anti-HCV-positive patients taken 223 days prior to and up to 1719 days after liver transplantation to determine if cumulative immunosuppression, rejection, or histologic recurrence correlated with HCV-RNA levels. Histologic, serum chemistry, cumulative steroid, and OKT3 and alpha-interferon (INF) dose data were collected at the time of HCV-RNA sampling. Eighteen of 24 evaluable patients (75%) had HCV-RNA detected in their sera after transplant. Eight patients had 14 rejection episodes, 9 patients received OKT3, and 5 were given INF for histologically moderate hepatitis. Five patients died - two of recurrent hepatitis C - and no retransplants were performed for recurrent hepatitis. Of the 23 survivors, 7 have histologic hepatitis - 2 with persistent ascites, and 2 with mild fibrosis. We could show no correlation between HCV-RNA levels and any of the variables examined although a trend toward increasing HCV-RNA levels with increasing numbers of rejection episodes was observed. In addition, histologic recurrence occurred more frequently for patients treated with OKT3. We conclude that the quantity of circulating viral genome is not influenced by immunosuppressive load and does not correlate with laboratory or histologic signs of recurrence. The roles that rejection, and possibly OKT3, play in the recurrence of HCV after liver transplant need further study.

Pharmacological activity of DC-015, a novel potent and selective alpha 1-adrenoceptor antagonist

The pharmacological activity of 3-((4-(2-methoxyphenyl)piperazin-1-yl)methyl)-2,3-dihydroimidaz o(1,2 -c)quinazolin-5(6H)-one (DC-015), a newly synthesized quinazoline derivative, was determined in rat isolated thoracic aorta and pressor responses were determined in spontaneously hypertensive rats (SHR). Experimental results indicated that DC-015 is an alpha 1-adrenoceptor-blocking agent in rat thoracic aorta as revealed by its competitive antagonism of phenylephrine-induced vasocontraction (pA2 = 10.54 +/- 0.55). These effects still persisted in denuded aorta. It was as potent as prazosin (pA2 = 10.04 +/- 0.63). At higher concentration (1.0 microM), DC-015 also expressed 5-hydroxytryptamine (5-HT) receptor competitive antagonism, but this 5-HT blocking effect was not found in the prazosin-administration group. [3H]Inositol monophosphate formation stimulated by phenylephrine (30 microM) in rat thoracic aorta was diminished by DC-015 (3 and 10 nM) and prazosin (10nM); whereas the cAMP content of rat thoracic aorta was not altered by DC-015 and prazosin. Furthermore, intravenous administration of DC-015 and prazosin (both at 0.01, 0.05 and 0.1 mg/kg-1) induced a dose-dependent reduction of mean arterial pressure which reached a maximal effect at 5 mm after injection and persisted over 2 h in SHR. A higher dose of DC-015 (0.1 mg/kg-1, i.v.) did not cause any significant changes in heart rate, whereas, the same dose of prazosin (0.1 mg/kg-1, i.v.) produced a decrease which seems to parallel the time course of the hypotensive response. We can conclude that the DC-015 is a potent, highly selective alpha 1-adrenoceptor antagonist in vascular smooth muscle.

Video-assisted thoracoscopic surgery for pneumothorax

Five cases of spontaneous pneumothorax were treated with video-assisted thoracoscopic surgery (VATS). These included four cases of recurrent pneumothorax and one case of persistent pneumothorax. The mean age was 33 years. The identified bullae were eliminated with either endoloop ligation (in one patient) or stapled excision (in four patients). There were no recurrences reported in a mean follow-up of 9.4 months. In conclusion, VATS offers an equally effective and less morbid alternative to open thoracotomy in the management of primary spontaneous pneumothorax.

Receptor binding dependent structural changes in human choriogonadotropin: photochemical inter-subunit crosslinking

Activation of surface receptors is thought to occur in multiple transient steps with conformational adjustments of hormones and receptors beginning from the initial hormone-receptor contact. In this study, we have established a sensitive photochemical crosslinking method to detect structural change of hCG upon receptor binding. hCG consists of an α subunit and a β subunit. Free α subunit was derivatized with photosensitive reagents and reassociated with unmodified β subunit. Reassociated hCG αβ dimer was capable of high affinity receptor binding and activation. The reagents attached to the α subunit were capable of crosslinking the α subunit to the β subunit. However, the extent of inter-subunit cross-linking in solution was two-three fold greater than inter-subunit crosslinking after hCG bound to the receptor. This difference indicates a novel structural change at the subunit interface in response to hCG binding to the receptor. Although highly unlikely, other microenvironmental factors might have interfered with the crosslinking efficiency without impacting the structure of hCG. This study lays the ground work to precisely define the location and nature of the change. Such information will be crucial for the understanding of the molecular mechanism of the hormone-receptor interaction and receptor activation.

Chronic exercise enhances endothelium-mediated dilation in spontaneously hypertensive rats

This study investigated the effect of physical training on endothelial function in spontaneously hypertensive rats (SHR). After 3 months, in conscious trained- and untrained-SHR body weight, systolic blood pressure and heart rate were 220 +/- 6 g vs 271 +/- 9 g, 172 +/- 7 mmHg vs 210 +/- 8 mmHg and 314 +/- 10 vs. 348 +/- 12 beats/min, respectively. In vitro, the dose-response curves of norepinephrine in isolated intact aortic and mesenteric rings form the exercise trained-SHR were significantly lower than those from the untrained-SHR. With denuded preparations, norepinephrine concentration-response curves were shifted to the left both in the trained- and untrained-SHR. This shift in the trained-SHR exceeded that in the untrained-SHR. The vasodilator response to acetylcholine in the trained-SHR was significantly greater than that in the untrained-SHR. Either N omega-nitro-L-arginine (100 mumol/l) or methylene blue (10 mumol/l) inhibited acetylcholine-induced vasodilator effect in aorta of trained- and untrained-SHR, but not in mesenteric artery of trained-SHR. Tetraethylammonium (10 mmol/l) inhibited significantly the N omega-nitro-L-arginine and methylene blue-resistant relaxation in mesenteric artery of trained-SHR, but not only by indomethacin (10 mumol/l). Collectively, these data demonstrate that chronic exercise increases EDRF/EDHF production (presumably by increasing endothelial shear stress), and may contribute to the enhanced effects of post-exercise hypotension.

Cilazapril reverses endothelium-dependent vasodilator response to acetylcholine in mesenteric artery from spontaneously hypertensive rats

This study was designed to evaluate the effect of chronic treatment with cilazapril on vascular reactivity of aorta and mesenteric artery from Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR). Cilazapril (5 mg/kg), an angiotensin converting enzyme inhibitor, was injected intraperitoneally twice a day for 4 weeks. Results demonstrated that acetylcholine (ACh)-induced relaxation in aorta and mesenteric artery from SHR was significantly less than that from WKY, cilazapril-treated WKY, and SHR. The impairment of ACh-induced relaxation in SHR was significantly reversed after cilazapril treatment and there were no significant differences among WKY, cilazapril-treated WKY, and SHR. Meanwhile, both N omega-nitro-L-arginine (LNNA; 10(-4) mol/L) and methylene blue (MB; 10(-5) mol/L) completely blocked the vasodilator response to ACh in aorta but only partly inhibited in mesenteric artery from WKY, cilazapril-treated WKY, and SHR. These LNNA- and MB-resistant vasodilator responses to ACh in mesenteric artery were only slightly inhibited by TEA (10(-3) mol/L) but not by indomethacin (5 x 10(-6) mol/L). These findings suggest that there may be an unidentified endothelium-dependent relaxing factor(s) (EDRF), which exists in the endothelium and may participate in the modulation of blood pressure in SHR. Results further demonstrate that the antihypertensive effect of cilazapril may be partly mediated by the reversing function of endothelium to release EDRF and LNNA-resistant, unidentified relaxing factor(s).

BN-063, a newly synthesized adenosine A1 receptor agonist, attenuates myocardial reperfusion injury in rats

To assess the efficacy of the newly synthesized selective adenosine A1 receptor agonist, BN-063 (1-cyclopropylisoguanosine), against myocardial reperfusion injury, 31 rats underwent 45 min of left coronary artery occlusion and 1 h of reperfusion. Animals were randomly assigned to four groups: control, I0.5-R0.5, in which BN-063 (0.5 mg/kg i.v. bolus) was administered during both ischemia and reperfusion, R-0.5 and R-1.0, in which BN-063 was administered only during reperfusion at 0.5 and 1.0 mg/kg, respectively. The area at risk was determined by intravascular injection of blue dye during coronary artery occlusion, which was performed by retightening the ligature at the end of reperfusion, and infarct size was determined by incubation of heart slices in nitro blue tetrazolium chloride. A significant reduction in infarct size, as a percentage of the area at risk, was noted with all three BN-063 treatment groups (control: 63.5 +/- 4.0%, I0.5-R0.5: 39.6 +/- 3.7%, R-0.5: 37.5 +/- 3.5%, R-1.0: 38.1 +/- 5.2%). However, the I0.5-R0.5 group did not shown a more beneficial effect than the other two BN-063-treated groups. In addition, BN-063 exerted a protective effect on the number of ventricular premature contractions associated with reperfusion (control: 906 +/- 52, I0.5-R0.5: 325 +/- 61, R-0.5: 321 +/- 95, R-1.0: 340 +/- 46). The results of this study demonstrate that BN-063, through activation of adenosine A1 receptors, exerts antiarrhythmic and anti-infarct effects during myocardial ischemia-reperfusion. Therefore, BN-063 would be useful clinically in the treatment and prevention of acute myocardial infarction.

Cyproheptadine augmentation of haloperidol in chronic schizophrenic patients: a double-blind placebo-controlled study

A 6 week double-blind placebo-controlled trial of cyproheptadine augmentation of ongoing haloperidol treatment was conducted in 40 chronic schizophrenic in-patients. Cyproheptadine augmentation, compared to administration of haloperidol with placebo, did not produce a statistically significant improvement in psychotic symptoms. Cyproheptadine augmentation caused significant reduction in the extrapyramidal symptoms, which supports the atypical profile of antipsychotics. As to the neuroendocrinological effect, cyproheptadine augmentation did not reduce the plasma prolactin level but did induce a decrease in the plasma cortisol level. Although long-term follow-up studies are needed to confirm the results, this study suggests that cyproheptadine augmentation may be effective in treating chronic schizophrenic patients who are intolerant of extrapyramidal side effects of conventional antipsychotics.

Retinoic acid stage-dependently alters the migration pattern and identity of hindbrain neural crest cells

This study investigates the migration patterns of cranial neural crest cells in retinoic acid (RA)-treated rat embryos using DiI labeling. Wistar-Imamichi rat embryos were treated at the early (9.0 days post coitum, d.p.c.) and late (9.5 d.p.c.) neural plate stages with all-trans RA (2 × 10(−7) M) for 6 hours and further cultured in an RA-free medium. RA exposure stage dependently induced two typical craniofacial abnormalities; that is, at 9.0 d.p.c. it reduced the size and shape of the first branchial arch to those of the second arch, whereas, in contrast, at 9.5 d.p.c. it induced fusion of the first and second branchial arches. Early-stage treatment induced an ectopic migration of the anterior hindbrain (rhombomeres (r) 1 and 2) crest cells; they ectopically distributed in the second branchial arch and acousticofacial ganglion, as well as in their original destination, i.e., the first arch and trigeminal ganglion. In contrast, late-stage treatment did not disturb the segmental migration pattern of hindbrain crest cells even though it induced the fused branchial arch (FBA); labeled crest cells from the anterior hindbrain populated the anterior half of the FBA and those from the preotic hindbrain (r3 and r4) occupied its posterior half. In control embryos, cellular retinoic acid binding protein I (CRABP I) was strongly expressed in the second branchial arch, r4 and r6, while weakly in the first arch and r1-3. CRABP I was upregulated by the early-stage treatment in the first branchial arch and related rhombomeres, while its expression was not correspondingly changed by the late-stage treatment. Moreover, whole-mount neurofilament staining showed that, in early-RA-treated embryos, the typical structure of the trigeminal ganglion vanished, whereas the late-stage-treated embryos showed the feature of the trigeminal ganglion to be conserved, although it fused with the acousticofacial ganglion. Thus, from the standpoints of morphology, cell lineages and molecular markers, it seems likely that RA alters the regional identity of the hindbrain crest cells, which may correspond to the transformation of the hindbrain identity in RA-treated mouse embryos (Marshall et al., Nature 360, 737–741, 1992).

Transcriptional activation of the alpha-1 acid glycoprotein gene by YY1 is mediated by its functional interaction with a negative transcription factor

Regulation of alpha-1 acid glycoprotein (AGP) gene expression involves both positive and negative transcription factors. We have previously identified two dominant factors: positive and negative transcription factors, AGP/EBP and factor B, respectively, involved in the transcription of AGP and other acute-phase response genes. In this report, we present evidence showing that the transcription of the AGP gene is positively regulated by a transcription factor, YY1. The activation of AGP gene by YY1 is mediated by a negative element B in the AGP promoter region. YY1 can also activate the B motif linked to a heterologous promoter. However, YY1 does not bind directly to the B motif per se. Rather, our data suggest that the activation of AGP gene by YY1 may be mediated by its functional interaction with factor B, which recognizes the B motif.

Purification and characterization of nucleolin and its identification as a transcription repressor

Expression of the acute-phase response genes, such as that for alpha-1 acid glycoprotein (AGP), involves both positive and negative transcription factors. A positive transcription factor, AGP/EBP, and a negative transcription factor, factor B, have been identified as the two most important factors responsible for the induction of the AGP gene. In this paper we report the purification, characterization, and identification of a B-motif-binding factor from the mouse hepatoma cell line 129p. The purified factor has been identified as nucleolin by amino acid sequence analysis. Biochemical and functional studies further established that nucleolin is a transcription repressor for regulation of AGP and possibly other acute-phase response genes. Thus, in addition to the many known functions of nucleolin, such as rRNA transcription, processing, ribosome biogenesis, and the shuttling of proteins between the cytoplasmic and nuclear compartments, it may also function as a transcriptional repressor.

Antiarrhythmic effects of BN-063, a newly synthesized adenosine A1 agonist, on myocardial ischaemia in rats

1. It has been shown that adenosine is able to reduce the severity of arrhythmias induced by myocardial ischaemia. In isolated preparations, the antiarrhythmic effect of adenosine on ventricular myocardium is known to antagonize the catecholamine-induced stimulation of intracellular cyclic AMP production, an effect mediated via adenosine A1 receptors. 2. The aim of this study was to evaluate the antiarrhythmic effect of BN-063 (1-cyclopropylisoguanosine), a newly synthesized selective adenosine A1 agonist, on ventricular arrhythmias in rats. 3. Arrhythmias were induced by left coronary artery ligation or by administration of isoprenaline (7 mg kg-1) subcutaneously. Pretreatment with BN-063 (0.25, 0.5 and 1.0 mg kg-1) 10 min prior to occlusion significantly delayed the onset of ventricular arrhythmias, reduced the total number of ventricular premature contraction (VPC) and ventricular tachycardia (VT), decreased the incidence of VT and ventricular fibrillation (VF) and mortality during the first 30 min following left coronary artery ligation. In contrast, pretreatment with 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), an adenosine A1 antagonist, was arrhythmogenic during the ischaemic period. The rate-pressure product, an index for indirect measurement of myocardial oxygen consumption, was also significantly reduced by BN-063 during ligation time. 4. The incidence of VT, VF and mortality was also significantly reduced when BN-063 was administered after left coronary artery ligation. 5. BN-063 converted the VF induced by isoprenaline to normal sinus rhythm and improved the survival rate. 6. It is concluded that, through activation of adenosine A1 receptors, BN-063 can suppress ventricular arrhythmias induced by myocardial ischaemia and catecholamines. The antiarrhythmic actions of BN-063 may be mediated by reducing heart rate and antagonizing the stimulatory effects of catecholamine in myocardial ischaemia.

Bovine conglutinin gene exon structure reveals its evolutionary relationship to surfactant protein-D

Bovine conglutinin (BC), a member of the mammalian C-type collectin subfamily, is a serum protein synthesized in liver that is believed to play a role in natural host defense. Previously, we have characterized a full length BC cDNA and we now describe the partial characterization of a genomic clone that encodes for the BC gene (CGN1). BC is encoded by nine exons spanning &gt; 11 kb and has been localized previously to band 18 of bovine (Bos taurus) chromosome 28. Genomic sequencing demonstrated that the signal peptide/amino-terminal domain, the carbohydrate recognition domain, and the linking peptide, a domain between the collagenous region and the carbohydrate recognition domain, are each encoded by a single exon. The collagenous domain is split into five exons, with the 5' most region being located within the exon that also encodes the signal peptide/amino terminus. The remaining four collagenous domain exons are tandemly arranged with lengths of 117, 108, 108, and 117 bp, respectively. Overall, the BC genomic organization is very similar to that of the human surfactant protein-D gene, SFTP4. On the basis of identical collagen domain structures, we suggest that conglutinin and bovine surfactant protein-D evolved from a gene duplication event occurring in Bovidae after divergence from other mammals.

Bovine conglutinin gene exon structure reveals its evolutionary relationship to surfactant protein-D

Bovine conglutinin (BC), a member of the mammalian C-type collectin subfamily, is a serum protein synthesized in liver that is believed to play a role in natural host defense. Previously, we have characterized a full length BC cDNA and we now describe the partial characterization of a genomic clone that encodes for the BC gene (CGN1). BC is encoded by nine exons spanning > 11 kb and has been localized previously to band 18 of bovine (Bos taurus) chromosome 28. Genomic sequencing demonstrated that the signal peptide/amino-terminal domain, the carbohydrate recognition domain, and the linking peptide, a domain between the collagenous region and the carbohydrate recognition domain, are each encoded by a single exon. The collagenous domain is split into five exons, with the 5' most region being located within the exon that also encodes the signal peptide/amino terminus. The remaining four collagenous domain exons are tandemly arranged with lengths of 117, 108, 108, and 117 bp, respectively. Overall, the BC genomic organization is very similar to that of the human surfactant protein-D gene, SFTP4. On the basis of identical collagen domain structures, we suggest that conglutinin and bovine surfactant protein-D evolved from a gene duplication event occurring in Bovidae after divergence from other mammals.