Self-assembled monolayers of new dendron-thiols: manipulation of the patterned surface and wetting properties

SAMs based on a novel dendron-thiol system, which maintain the alkanethiols' active site, but with the -SH group connected to independently variable groups by a dendron-linker, showed a controllable surface pattern and wetting properties. The precisely tailored structure of dendron-thiols with locally controlled hydrophobic and hydrophilic peripheries allows the formation of designed surface structures on a gold surface, e.g. nano-stripes, honeycomb and homogeneous structures.

Interleukin-6 production by endothelial cells via stimulation of protease-activated receptors is amplified by endotoxin and tumor necrosis factor-alpha

Human endothelial cells respond to extracellular proteases, endotoxin (lipopolysaccharide, LPS), and inflammatory cytokines. Endothelial cells express several protease-activated receptors (PAR), including the thrombin-activated receptors PAR-1 and PAR-3 and a thrombin-independent, protease-activated receptor, PAR-2. To examine the potential cooperation between PAR and inflammatory stimuli, we investigated the effects of the PAR-1 agonist peptide Ser-Phe-Leu-Leu-Arg-Asn (SFLLRN) and PAR-2 agonist peptide Ser-Leu-Ile-Gly-Lys-Val (SLIGKV) on endothelial cells. Human umbilical vein endothelial cells (HUVEC) were cultured in vitro with SFLLRN or SLIGKV in the presence and absence of LPS or tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) levels in the culture supernatants were assayed. Both SFLLRN and SLIGKV induced detectable levels of IL-6 production in a dose-dependent fashion, with the PAR-1 receptor agonist being more potent. In the presence of all stimulatory concentrations of LPS or TNF-alpha tested, both peptides were found to further enhance IL-6 production. The effects of SFLLRN and SLIGKV were specific, as related peptides with identical amino acid compositions, but lacking in consensus sequences, were biologically inactive either alone or in the presence of LPS. Both the direct and the amplifying effects of PAR agonist peptides on IL-6 production were pertussis toxin sensitive and caused an increase in the intracellular levels of calcium, implicating G-proteins and calcium mobilization in these pathways. Furthermore, the amplifying effect of LPS or TNF-alpha on PAR-mediated cytokine production was associated with corresponding increases in nuclear NF-kappaB proteins. The results demonstrate significant potentiation of PAR-induced signaling by LPS and TNF-alpha and indicate the potential cooperation of proteases and inflammatory stimuli in amplifying vascular inflammation.

K(2)SrIn(7): an electron-deficient indium network structure that reflects limitations of cation accommodation. synthesis, structure, and bonding

A new phase in the K-Sr-In system was discovered following direct fusion of the neat elements in a niobium tube at 900 degrees C and equilibration at 700 degrees C for 5 days. Single-crystal X-ray diffraction analysis reveals that K(2)SrIn(7) crystallizes in an orthorhombic system, space group Cmcm, Z = 4, a = 5.0455(5) A, b = 11.960(2) A, c = 19.762(4) A. The structure contains a three-dimensional In network built of sheets of condensed pentagonal prismatic columns interbonded along. Two rather different types of channels are separately occupied by K and Sr atoms, the latter centered in 15-atom indium polyhedra. Band structure calculations and resistivity and susceptibility measurements indicate that the compound is metallic and diamagnetic. The one-electron deficiency in the valence band per formula unit brought on by the limited cation count is analyzed in terms of the character of the bonding, some of that from multicenter In bonding falling above E(F).

Histamine-induced production of interleukin-6 and interleukin-8 by human coronary artery endothelial cells is enhanced by endotoxin and tumor necrosis factor-alpha

In this study, we tested the synergy between histamine and LPS, and histamine and TNF-alpha, on endothelial cell production of interleukin-6 (IL-6), interleukin-8 (IL-8), and monocyte chemoattractant protein-1 (MCP-1). Human coronary artery endothelial cells (HCAEC) were cultured in vitro with histamine (0.1 to 1000 microM) in the presence or absence of LPS or TNF-alpha for 24 h, and the secreted IL-6, IL-8 and MCP-1 were quantified. Unactivated HCAEC produced minimal levels of IL-6, IL-8, or MCP-1. The incubation of HCAEC with histamine resulted in low level induction of IL-6 and IL-8 production, which was dose-dependent and attained a plateau at a concentration of 10 microM. On the other hand, histamine failed to induce MCP-1 production. Stimulation of HCAEC with LPS or TNF-alpha caused dose-dependent increase in cytokine production. In the presence of all stimulatory concentrations of LPS and TNF-alpha tested, histamine was shown to further enhance IL-6 and IL-8 production. The effect of histamine on endothelial cell production of cytokines was completely inhibited by the H-1 receptor antagonist, diphenhydramine, and not by the H-2 antagonist, famotidine. Electrophoretic mobility shift assays of nuclear proteins extracted from HCAEC treated with histamine and LPS, or histamine and TNF-alpha, revealed amplified translocation of NF-kappaB proteins to the nuclei. Since both LPS and TNF-alpha potentiated histamine-induced cytokine production, it is possible that these activators stimulate H-1 receptor expression and/or augment the signal transduction pathways leading to the expression of IL-6 and IL-8. These results indicate the importance of synergy between histamine and other inflammatory stimuli on endothelial cell activation and implicate their cooperative participation in vascular leak and inflammation.

Temporal relationships among uterine pituitary adenylate cyclase-activating polypeptide, decidual prolactin-related protein and progesterone receptor mRNAs expressions during decidualization and gestation in rats

Pituitary adenylate cyclase-activating peptide (PACAP), a novel compound with vasoactive intestinal polypeptide-like activity, was recently shown to be localized in the neuronal endings of the human uterus. The purpose of the present study was to assess the functional presence of PACAP mRNA in the decidual endometrium and its relationship to the expression levels of decidual prolactin-related protein (dPRP) and the progesterone receptor mRNAs during decidualization and pregnancy in Sprague-Dawley rats. PACAP was constitutively and temporally expressed in the decidual endometrium and gravid uterus. The time-dependent correlated expression levels of PACAP, dPRP and the progesterone receptor were induced by the neurogenic reproductive signals, i.e. the vagino-cervical/deciduogenic stimuli of decidualization and by the normal equivalent stimuli of mating/blastocyst implantation of gestation. Correlation among the mRNA expression levels of PACAP, dPRP and the progesterone receptor and the coordinated inhibitory actions of the anti-progesterone (RU-486) suggest that there is also correlated time-dependent steroid regulation of the mRNA levels of PACAP, dPRP and the progesterone receptor in the decidual and pregnant uteri. One possible functional meaning for the time-related localization of endometrial/uterine PACAP could be to facilitate endometrial blood flow and increase the availability of metabolic substrates to the developing deciduoma or embryo. The study demonstrates the potential importance of PACAP expression in the regulation of the maternal feto-placental component and suggests a prominent reproductive role for the neuropeptide in mammalian pregnancy.

A mechanistic assessment of 1,3-butadiene diepoxide-induced inhibition of uterine deciduoma proliferation in pseudopregnant rats

Butadiene diepoxide (BDE), a reactive metabolite of 1,3-butadiene that is an important industrial chemical used in synthetic rubber production causes a dose-dependent inhibition of deciduoma development in pseudopregnant Sprague-Dawley rats. This study used 4 daily i.p. BDE doses of 0.20, 0.25, 0.30, 0.35, or 0.40 to characterize mechanisms that may be responsible for the antideciduoma effect. Pseudopregnant rats were treated either before (pseudopregnancy [PPG] days 1-4) or after (PPG days 5-9) deciduoma induction by endometrial trauma with a blunt needle. Animals were killed on PPG day 9 and evaluated for serum progesterone and endometrial protein and DNA. RT-PCR was used to measure message for estrogen receptor (ER) alpha and pituitary adenylate cyclase-activating polypeptide (PACAP). Substrate zymography and Western blotting were used respectively to measure matrix metalloproteinase (MMP)-9 and inducible nitric oxide synthase. The antideciduoma effects of BDE were associated with decreases in endometrial weight, protein, and DNA, with decreases in serum progesterone, and with decreases in PACAP message and MMP-9. A reduction in NOS was identified at the highest dose of BDE. Message for estrogen receptor (ER) alpha was not affected at any dose. We conclude that the reduction in decidual proliferation was direct and appeared to be associated with either 1) a decrease in the effectiveness of the deciduogenic stimulation and/or a weakened endometrial sensitivity to the stimulus; or 2) an effect on deciduoma development. Molecular mechanisms that apparently contributed to BDE inhibition of decidual metabolism included the synthesis of protein and DNA involved in decidual growth, the synthesis and activation of a matrix metalloproteinase for degradation of the extracellular matrix that is essential for tissue remodeling during deciduoma development, and the nitric oxide/nitric oxide synthase and pituitary adenylate cyclase-activating peptide systems that are involved in promoting vasodilation and increased vascular permeability to enhance the availability of substrates for maximal deciduoma growth. The ovotoxicity of BDE, which has previously been established, may indirectly affect decidual proliferation by reducing progesterone, the preeminent endocrine regulator of deciduoma development. The findings also suggest that BDE may possess no estrogenic action since it was associated with endometrial weight loss and unaltered levels of the estrogen receptor alpha mRNA expression.

K6Tl2Sb3, A Zintl Phase with a Novel Heteroatomic [Tl4Sb612-] Chain1

The title compound with heteratomic anionic chains [Tl(4)Sb(6)(12)(-)] has been discovered in the K-Tl-Sb system. The phase is obtained from a range of compositions near K(3)TlSb(1.5) following reaction first at 750-850 degrees C and then at 550 degrees C for one week or more. It crystallizes in the monoclinic system in space group C2/c, Z = 8, a = 9.951(1) A, b = 17.137(3) A, c = 19.640(6) A, and beta = 104.26(3) degrees. Swing-like (Tl(4)Sb(6))(12)(-) units consisting of alternating Sb and Tl atoms in four- and eight-membered rings are linked through Tl-Tl bonds to form infinite one-dimensional chains along a. EHTB calculations and resistivity measurements show that the compound is a semiconductor.

Nucleic acid supercoiling as a means for ionic switching of DNA--nanoparticle networks

Oligomeric nanoparticle networks, generated by the self-assembly of bis-biotinylated double-stranded DNA fragments and streptavidin, have been studied by scanning force microscopy (SFM). SFM imaging revealed the presence within the networks of irregular thick DNA molecules, which were often associated with distinct, Y-shaped structural elements. Closer analysis revealed that the Y structures are formed by condensation (thickening and shortening) of two DNA fragments, most likely through the supercoiling of two DNA molecules bound to adjacent binding sites of the streptavidin particle. The frequency of supercoiling was found to be dependent on the ionic strength applied during the immobilization of the oligomeric networks on mica surfaces. Potential applications of the structural changes as a means for constructing ion-dependent molecular switches in nanomaterials are discussed.

Non-hemostatic activity of coagulation factor Xa: potential implications for various diseases

Because of its unique position at the convergence point of the intrinsic (contact) and extrinsic (tissue factor/factor VIIa) pathways in the coagulation system, coagulation factor Xa (FXa) has been a theoretically interesting therapeutic target for antithrombotic drugs for many years. More recently, the discovery of naturally occurring FXa inhibitors, such as tick anticoagulant peptide and antistasin, has helped substantiate FXa as a desirable target by demonstrating the efficacy and potential safety advantages of FXa inhibition over conventional antithrombotic therapy. These discoveries led to the design and development of many small-molecule inhibitors of FXa, which have provided potent and selective tools for evaluating the potential role of FXa in various diseases. In addition, these advances have been instrumental in defining the biology of FXa and have aided in the discovery of specific receptors and intracellular signaling pathways for FXa that may be important in the progression of, or the response to, various diseases.

Antithrombotic effect of LB-30057 (CI-1028), a new synthetic thrombin inhibitor, in a rabbit model of thrombosis: comparison with inogatran

LB-30057 (CI-1028) is a novel, orally bioavailable, direct thrombin inhibitor with a Ki of 0.38 nM against human thrombin. The effects of LB-30057 on thrombus formation and hemostasis were evaluated in a veno-venous shunt model of thrombosis in rabbits, and compared with inogatran, another direct inhibitor of thrombin. Each compound was studied at 5 or 6 different doses with 5 or 6 rabbits in each group. After administration as a bolus i.v. injection followed by continuous infusion, both LB-30057 and inogatran dose-dependently inhibited thrombus formation, which was measured as an increase in time to occlusion (TTO) and a decrease in thrombus weight. Both compounds also improved vena caval blood flow and reduced the overall incidence of thrombotic occlusion. LB-30057 significantly prolonged TTO from 23 +/- 4 min (before dose) to 110 +/- 10 min at the highest dose (0.7 mg/kg + 47 microg/kg/min) (p < 0.001), and reduced thrombus weight from 57 +/- 2 mg to 15 +/- 5 mg (p < 0.001). Occlusive thrombus formed in only one of six rabbits that received the highest dose of LB-30057 (vs. 13/13 in the control group, p < 0.01). At the dose that produced the maximum antithrombotic effect (0.7 mg/kg + 47 microg/kg/min), LB-30057 increased aPTT and bleeding time approximately 2-and 2.5-fold above baseline, respectively. On a gravimetric basis, LB-30057 and inogatran displayed comparable in vivo antithrombotic efficacy. When compared to equally effective anti thrombotic doses of inogatran, LB-30057 caused less prolongation in aPTT, had no effect on PT, and tended to have less of effect on bleeding time. These results indicate that LB-30057 is an effective antithrombotic compound and it appears to have a better benefit/risk profile than inogatran in this experimental model.

Fast-track cardiac anesthesia: a comparison of remifentanil plus intrathecal morphine with sufentanil in a desflurane-based anesthetic

OBJECTIVE

To compare the effects of an intravenous remifentanil infusion plus intrathecal morphine with intravenous sufentanil infusion with respect to intraoperative hemodynamic variables, extubation times, and recovery profiles when administered as part of a desflurane-based fast-track anesthetic regimen for cardiac surgery.

DESIGN

A prospective, randomized, nonblinded study.

SETTING

University hospital.

PARTICIPANTS

Forty patients undergoing elective primary coronary artery bypass graft, aortic valve replacement, or mitral valve replacement surgery.

INTERVENTIONS

After a standardized anesthetic induction, anesthesia was maintained with a remifentanil infusion, 0.1 microg/kg/min, and desflurane, 3% to 10%, inspired (group I, n = 20) or a sufentanil infusion, 0.3 microg/kg/h, and desflurane, 3% to 10%, inspired (group II, n = 20). Patients receiving remifentanil were administered intrathecal morphine, 8 microg/ kg, for postoperative analgesia.

MEASUREMENTS AND MAIN RESULTS

Both anesthetic regimens provided comparable intraoperative hemodynamic stability and similar recovery profiles, with extubation times of 5.1 +/- 4.3 hours (group I) and 5.8 +/- 6.7 hours (group II).

CONCLUSIONS

Use of remifentanil in combination with intrathecal morphine did not facilitate earlier tracheal extubation or improve intraoperative hemodynamic stability compared with sufentanil alone for fast-track cardiac anesthesia.

Rational design, synthesis, and biological activity of benzoxazinones as novel factor Xa inhibitors

Inappropriate thrombus formation within blood vessels is the leading cause of mortality in the industrialized world. Factor Xa (FXa) is a trypsin-like serine protease that plays a key role in the blood coagulation cascade and represents an attractive target for anticoagulant drug development. From a high-throughput in vitro mass screen of our chemical library, we identified 4-[5-[(2R,6S)-2, 6-dimethyltetrahydro-1(2H)-pyridinyl]pentyl]-2-phenyl-2H-1, 4-benzoxazin-3(4H)-one (1a) as an inhibitor of FXa with an IC(50) of 27 microM. Through a combination of SAR studies and molecular modeling, we synthesized 3-(4-[5-[(2R,6S)-2, 6-dimethyltetrahydro-1(2H)-pyridinyl]pentyl]-3-oxo-3,4-dihydro-2H- 1,4-benzoxazin-2-yl)-1-benzenecarboximidamide (1n) which was a potent FXa inhibitor with an IC(50) of 3 nM. This compound exhibited high selectivity for FXa over other related serine proteases and was efficacious when dosed intravenously in rabbit and dog antithrombotic models.

[The postburn "shock heart"]

OBJECTIVE

To investigate the pathogenesis of postburn "shock heart".

METHODS

A combined serial studies in both animal experiments and prospective clinical investigation were carried out with the determination of indices reflecting myocardial injury, such as cardiac function, myocardial injury parameters, cytoplasmic and cytoskeletal structure injury, myocardial biomechanics and pathomorphological changes. The pathogenesis was also explored by the evaluation of myocardial nutritional blood flow (NBF), cardiac myocytic oxygen consumption, energy metabolism and cytokines released from cardiac myocytes.

RESULTS

Cardiac function, myocardial biomechanics, NBF, the oxygen consumption, energy metabolism and the viscoelastic properties of cardiac myocytes decreased significantly postburn, and myocyte cytoplasm and cytoskeleton were damaged after burn. Furthermore, focal dissolution and fragmentation of myocardiac fibers were observed. In the meantime the plasma levels of CM -- LC, TnT and myocardial tissue cytokines increased markedly.

CONCLUSION

These results suggest that organic damage of cardiac myocytes occurred during postburn shock stage. The principle pathogenesis might be related to ischemic -- reperfusion injury, inability of oxygen utility and energy metabolism in cardiac myocytes, as well as myocardial edema and uncontrolled inflammatory response.

Hydroxyurea inhibition of cellular and developmental activities in the decidualized and pregnant uteri of rats

The cytotoxicity of hydroxyurea (HU), currently used to combat various cancers, sickle cell anemia and human immunodeficiency infection, was assessed by exposing decidualized and pregnant uteri of Sprague-Dawley rats to this drug. Consecutive daily doses of HU (500 mg/kg(-1)) for 4 days were injected subcutaneously during decidualization when proliferation of the deciduoma was biochemically analyzed on pseudopregnancy day 9, or injected intraperitoneally during pregnancy when uterine developmental processes were evaluated on gestation day 16. Hydroxyurea displayed prominent antiproliferative effects on decidual growth. These actions were comparable to significantly impaired (P<0.001) developmental responses (increases in post-implantation losses, in resorbed fetuses and in reduced fetal and placental weights) during pregnancy. The cellular components inhibited by HU were DNA, protein, nitric oxide synthase, a matrix metalloproteinase and decidual prolactin-related protein mRNA (P<0.05). Steroid-related endocrine events (serum progesterone concentrations, estrogen receptor and mRNA levels) were unaffected by HU, implying direct cellular action by the drug. Interestingly, endometrial alkaline phosphatase bioactivity was enhanced by HU (P<0.05). Subsequently, the reproductive toxicity of HU was apparently related to mitogenic and differentiation-induced endometrial cellular activities.

Fast-track cardiac anesthesia: use of remifentanil combined with intrathecal morphine as an alternative to sufentanil during desflurane anesthesia

The purpose of this cardiac fast-track study was to evaluate the use of remifentanil (R) combined with intrathecal (IT) morphine as an alternative to sufentanil (S) during desflurane anesthesia with respect to postoperative pain control. Prior to entering the operating room, patients in the R group (n = 20) received morphine, 8 microg/kg IT. Anesthesia was induced using a standardized anesthetic technique in all patients. In the R group, anesthesia was maintained with R, 0.1 microg. kg(-1). min(-1) in combination with desflurane 3-10%. In the S group (n = 20), patients received S 0.3 microg. kg(-1). h(-1) and desflurane 3-10%. There were no differences between the two groups with respect to time from arrival in the intensive care unit to tracheal extubation (5.1 +/- 4.3 h vs 5.8 +/- 6.7 h for R and S groups, respectively). After extubation, patients in the R group had significantly lower visual analog pain scores, reduced patient-controlled analgesic requirements, and greater satisfaction with their perioperative pain management, compared with patients in the S group. We conclude that R combined with IT morphine provided superior pain control after cardiac surgery compared with a S-based general anesthetic technique.

IMPLICATIONS

As part of a cardiac fast-tracking program involving desflurane anesthesia, the use of intrathecal morphine in combination with a remifentanil infusion provided improved postoperative pain control, compared with IV sufentanil alone.

Multiple interactions of the Asp(2.61(98)) side chain of the gonadotropin-releasing hormone receptor contribute differentially to ligand interaction

Mutation of Asp(2.61(98)) at the extracellular boundary of transmembrane helix 2 of the gonadotropin-releasing hormone (GnRH) receptor decreased the affinity for GnRH. Using site-directed mutagenesis, ligand modification, and computational modeling, different side chain interactions of Asp(2.61(98)) that contribute to high-affinity binding were investigated. The conservative Asp(2. 61(98))Glu mutation markedly decreased the affinity for a series of GnRH analogues containing the native His(2) residue. This mutant showed smaller decreases in affinity for His(2)-substituted ligands. The loss of preference for His(2)-containing ligands in the mutant receptor shows that Asp(2.61(98)) determines the specificity for His(2). Analysis of the affinities of a series of position 2-substituted ligands suggests that a hydrogen bond forms between Asp(2.61(98)) and the delta NH group of His(2) and that Asp(2. 61(98)) forms a second hydrogen bond with the ligand. Substitution of Asp(2.61(98)) with an uncharged residue further decreased the affinity for all ligands and also decreased receptor expression. Computational modeling indicates an intramolecular ionic interaction of Asp(2.61(98)) with Lys(3.32(121)) in transmembrane helix 3. The uncharged, Lys(3.32(121))Gln mutation also markedly decreased agonist affinity. The modeling and the similar phenotypes of mutants with uncharged substitutions for Asp(2.61(98)) or Lys(3.32(121)) are consistent with the presence of this helix 2-helix 3 interaction. These studies support a dual role for Asp(2.61(98)): formation of an interhelical interaction with Lys(3.32(121)) that contributes to the structure of the agonist binding pocket and an interaction with His(2) of GnRH that helps stabilize agonist complexing.

Recent advances in clinical trials of the direct and indirect selective Factor Xa inhibitors

Over the years, pharmacological intervention to prevent undesired intravascular coagulation and the associated detrimental effects has been a clinical challenge. The first generation of anticoagulant agents, warfarin and unfractionated heparin (UFH), involve indirect mechanisms of inhibiting the coagulation cascade. Fractionated, or low-molecular weight, heparins (LMWHs) are more selective for coagulation Factor Xa (FXa) over thrombin (FIIa). LMWHs also utilise an indirect mechanism of inhibition and have improved pharmacokinetic, pharmacodynamic and therapeutic profiles over UFH. The success of LMWHs, along with the pivotal location of FXa in the coagulation cascade, has prompted interest in the discovery and development of selective FXa inhibitors. There are two general classes of FXa inhibitors in development, of which SR90107A/ORG31540, an antithrombin-III-dependent pentasaccharide and DX-9065a, a small molecule direct FXa inhibitor, have published clinical data. SR90107A/ORG31540 and DX-9065a offer safe, predictable pharmacokinetic and pharmacodynamic profiles when administered subcutaneously and intravenously, respectively, to healthy volunteers and appear to be progressing through clinical development. The purpose of this review is to compile and summarise the published Phase I and II clinical data for SR90107A/ORG31540 and DX-9065a.

Contribution of in vivo models of thrombosis to the discovery and development of novel antithrombotic agents

Cardiovascular and cerebrovascular diseases continue to be the leading cause of death throughout the world. Over the past two decades, great advances have been made in the pharmacological treatment and prevention of thrombotic disorders (e.g., tissue plasminogen activators, platelet GPIIb/IIIa antagonists, ADP receptor antagonists such as clopidogrel, low-molecular weight heparins, and direct thrombin inhibitors). New research is leading to the next generation of antithrombotic compounds such as direct coagulation FVIIa inhibitors, tissue factor pathway inhibitors, gene therapy, and orally active direct thrombin inhibitors and coagulation Factor Xa (FXa) inhibitors. Animal models of thrombosis have played a crucial role in discovering and validiting novel drug targets, selecting new agents for clinical evaluation, and providing dosing and safety information for clinical trials. In addition, these models have provided valuable information regarding the mechanisms of these new agents and the interactions between antithrombotic agents that work by different mechanisms. This review briefly presents the pivitol preclinical studies that led to the development of drugs that have proven to be effective clinicallly. The role that animal models of thrombosis are playing in the discovery and development of novel antithrombotic agents is also described, with specific emphasis on FXa inhibitors. The major issues regarding the use of animal models of thrombosis, such as the use of positive controls, appropriate pharmacodynamic markers of activity, safety evaluation, species-specificity, and pharmacokinetics, are highlighted. Finally, the use of genetic models in thrombosis/hemostasis research and pharmacology is presented using gene-therapy for hemophilia as an example of how animal models have aided in the development of these therapies that are now being evaluated clinically. In summary, animal models have contributed greatly to the discovery of currently available antithrombotic agents and will play a primary role in the discovery and characterization of the novel antithrombotic agents that will provide safe and effective pharmacological treatment for life-threatening thrombotic diseases.

Self-assembly of DNA-streptavidin nanostructures and their use as reagents in immuno-PCR

The self-assembly of bis-biotinylated double-stranded DNA and the tetravalent biotin-binding protein streptavidin (STV) have been studied by non-denaturing gel electrophoresis and atomic force microscopy (AFM). The rapid self-assembly reproducibly generated populations of individual oligomeric complexes. Most strikingly, the oligomers predominantly contained bivalent STV molecules bridging two adjacent DNA fragments to form linear nanostructures. Trivalent STV branch points occurred with a lower frequency and the presence of tetravalent STV was scarce. However, valency distribution, size and the exchange dynamics of the supramolecular aggregates were highly sensitive to stoichiometric variations in the relative molar coupling ratio of bis-biotinylated DNA and STV. The largest aggregates were obtained from equimolar amounts while excess STV led to the formation of smaller oligomers appearing as fingerprint-like band patterns in electrophoresis. Excess DNA, however, induces a complete breakdown of the oligomers, likely a consequence of the instability of STV conjugates containing more than two biotinylated DNA fragments. It was demonstrated that the oligomers can further be functionalized, for instance by the coupling of biotinylated immunoglobulins. Both pure and also antibody-modified DNA-STV oligomers were used as reagents in immuno-PCR (IPCR), a highly sensitive detection method for proteins and other antigens. Employment of the supramolecular reagents led to an approximately 100-fold enhanced sensitivity compared to the conventional IPCR procedure.

The functional microdomain in transmembrane helices 2 and 7 regulates expression, activation, and coupling pathways of the gonadotropin-releasing hormone receptor

Structural microdomains of G protein-coupled receptors (GPCRs) consist of spatially related side chains that mediate discrete functions. The conserved helix 2/helix 7 microdomain was identified because the gonadotropin-releasing hormone (GnRH) receptor appears to have interchanged the Asp(2.50) and Asn(7.49) residues which are conserved in transmembrane helices 2 and 7 of rhodopsin-like GPCRs. We now demonstrate that different side chains of this microdomain contribute specifically to receptor expression, heterotrimeric G protein-, and small G protein-mediated signaling. An Asn residue is required in position 2.50(87) for expression of the GnRH receptor at the cell surface, most likely through an interaction with the conserved Asn(1.50(53)) residue, which we also find is required for receptor expression. Most GPCRs require an Asp side chain at either the helix 2 or helix 7 locus of the microdomain for coupling to heterotrimeric G proteins, but the GnRH receptor has transferred the requirement for an acidic residue from helix 2 to 7. However, the presence of Asp at the helix 7 locus precludes small G protein-dependent coupling to phospholipase D. These results implicate specific components of the helix 2/helix 7 microdomain in receptor expression and in determining the ability of the receptor to adopt distinct activated conformations that are optimal for interaction with heterotrimeric and small G proteins.

The Monolayer Behavior of Amphiphilic Polymer and Heterostructure of Polymer LB Film/CdS Clusters

In this paper we report the behavior of an amphiphilic polymer monolayer on pure water and Cd2+ subphase. This polymer was composed of hydrophilic ethylene diamine epichlorohydrin slightly crosslinked microgel and hydrophobic stearic chains, noted as ES-1. The introduction of Cd2+ ions in subphase had a marked effect on the process of the organization of the amphiphilic polymer at the air/water interface due to the association of Cd2+ ions with the hydrophilic network, which could be indicated by the pressure-area isotherms and Brewster Angle Microscopy. Ordered ES-1/Cd2+ LB multilayers were fabricated. After the multilayers reacted with H2S gas, CdS clusters were synthesized within the film, which was characterized by X-ray diffraction and UV-visible spectroscopy. Copyright 1999 Academic Press.

Biochemical characterization of benomyl inhibition on endometrial growth during decidualization in rats

The antimitotic action of the systemic benzimidazole carbamate compound, benomyl, the basis for its fungitoxicity, was assessed in a mammalian system by selected biochemical endpoints of endometrial proliferation during decidualization in rats. The deciduoma, artificially induced on Day 4 of pseudopregnancy (PG), represents the maternal portion of the placenta that attains maximal growth between Days 9-11 PG. Deciduoma induction by surgical uterine trauma normally prolongs PG into the decidualization process. Measured endometrial parameters were the wet weight, protein for hypertrophy, DNA indicative of hyperplasia; enzymatic biomarkers- isocitrate dehydrogenase (ICDH) and the matrix metalloproteinases (MMPs); and serum progesterone which hormonally maintains decidual growth. Benomyl was administered by oral gavage in daily doses (500 mg/kg/rat in corn oil for 5 days, PG Days 5-9) and animals were sacrificed on PG Day 10. Benomyl caused significant reduction (P < 0.001) in endometrial wet weight, protein and DNA concentrations. ICDH activity was also significantly reduced (P < 0.01) following benomyl treatment. Of the two MMP species (72 and 92 kDa), whereas the 72 kDa was only slightly affected, the 92 kDa MMP was suppressed 2-3 fold by benomyl. Benomyl was without effect on the progesterone concentration. The findings suggest that during decidualization in rats, the anti-deciduogenic, antimitotic action of post-traumal benomyl treatment which occurred via the biochemical molecules (protein, DNA, ICDH and the MMPs) apparently was not mediated by progesterone.

Effects of a factor Xa inhibitor, DX-9065a, in a novel rabbit model of venous thrombosis

The objective of this study was to evaluate the effects of DX-9065a, a nonpeptide, direct inhibitor of factor Xa (FXa), in a novel experimental model of venous thrombosis. The experiments were conducted on anesthetized rabbits in which a veno-venous shunt with cotton threads was inserted into the vena cava. DX-9065a was administered intravenously to the rabbits as an initial bolus followed by a maintenance infusion using the following dosing schedules: DX-I: 0.25 mg/kg + 3 micrograms/kg/min.; DX-II: 0.75 mg/kg + 9 micrograms/kg/min.; DX-III: 1.5 mg/kg + 18 micrograms/kg/min.; DX-IV: 3.0 mg/kg + 36 micrograms/kg/min.; DX-V: 6.0 mg/kg + 72 micrograms/kg/min. DX-9065a induced a dose-dependent increase in the time to occlusion and a dose-dependent decrease in thrombus weight. Because of the unique character of the model, we were also able to show a dose-dependent increase in blood flow through the shunt. In addition, there were dose-dependent increases in prothrombin time (PT) and activated coagulation time (ACT) with more variable responses in the activated partial thromboplastin time (APTT). DX-9065a had little effect on thrombin time (TT) or bleeding time at all doses tested. In conclusion, dose-dependent antithrombotic efficacy was documented with DX-9065a in this new model of venous thrombosis. Although the in vivo potency of the compound was not striking, the results support the utility of FXa inhibition in venous thrombosis and demonstrate the utility of this experimental model for evaluating the efficacy of novel anticoagulants.

[Investigation of factors affecting the development of COPD]

OBJECTIVE

To investigate the factors which affect the development of COPD.

METHODS

88 patients with mPAP less than 20 mm Hg were followed up by 5 - 20 years. Pulmonary ventilation, blood gas analysis, ECG, pulmonary hemodynamic parameters and oxygen saturation at night were performed one time every 5 years.

RESULTS

The results showed that: 5 year, 10 year and 20 year's mortality is 6%, 25% and 43% respectively; MVV%, FEV(1)% and PaO(2) declined accompanied by the increase of PaCO(2); among 41 patients with mPAP 16 - 20 mm Hg, 20 patients' mPAP were more than 20 mm Hg and 15 patients died after 10 years' follow up. Among 16 patients with the declination of oxygen saturation, 8 patients' mPAP were more than 20 mm Hg and 6 patients died. 57 strains of infectious bacteria were found in 88 patients' sputum with 43 strains in the death group.

CONCLUSIONS

These results demonstrated that COPD is a kind of chronic diseases with high death rate; infection, decline of oxygen saturation at night and mPAP more than 16 mm Hg were high risk factors in COPD.

Sutural mineralization of rat calvaria characterized by atomic-force microscopy and transmission electron microscopy

The application of transmission electron microscopy (TEM) and atomic-force microscopy (AFM) aid the acquisition of detailed structural information on the process of hard tissue formation. The sutural mineralization of rat calvaria is taken as a model for a collagen-related mineralization system. After cryofixation or chemical fixation an anhydrous tissue preparation technique with no staining procedures is used. The atomic-force microscope and the transmission electron microscope are used for structural analysis of the mineralizing region of the sutural tissue. With the application of AFM the collagen macroperiod is shown to be well represented in the unmineralized sutural tissue. At the mineralization front the collagen fibrils are found to be thickened and to change to a characteristic stacked platelet structure. Using TEM the macroperiod is faintly visible before mineral crystallites have formed and is more prominent after the apatite crystallization has started in the fibrils. In this step a needle-like structure of the newly formed apatitic crystals is visible.

Time-dependent relationship between the estrogen receptors and the matrix metalloproteinases following deciduoma induction in rats

The purpose of this study was to investigate time-related interactions between the estrogen receptors, mediators of steroidal regulation of uterine growth, and an extracellular regulatory enzyme, the matrix metalloproteinases (MMPs) engaged in connective tissue degradation and remodeling that are fundamental to implantation and placentation. Pseudopregnant rats, in which the decidual response, the basis for decidualization, was surgically induced on day 4 of pseudopregnancy (PG), were sacrificed on PG days 3, 6, 9, and 15 for retrieval of uterine tissues for assays: the radioligand binding assay for the estrogen receptors and substrate zymography for the MMPs. Following increases on PG day 3, there were time-dependent decreases in the cytosolic low and high capacity estrogen receptors during deciduoma development (PG days 6-9) and regression (PG day 15) in both the endometrium and myometrium. Moreover, whereas the low capacity estrogen receptor levels were only slightly decreased (PG days 6-15), the high capacity receptors were reduced on day 6 (P < 0.001) and were completely diminished during PG days 9 and 15. In contrast, the MMPs (92 and 72 kDa) activities were increased from PG days 6-15 (P < 0.05) over the pre-decidual induction values on PG day 3 in both uterine compartments. The results suggest that deciduoma induction can modulate the concentration of cytosolic estrogen receptor subtypes and MMP activities in rats. The inverse time-dependent interrelationship between these cellular and extracellular components during deciduoma development and regression imply that the remodeling role of the MMPs may be enhanced by the reduced cytosolic estrogen receptor/estrogen action.

A novel model of venous thrombosis in the vena cava of rabbits

The objective of this study was to develop and validate a new experimental model of venous thrombosis in the rabbit. A 3-cm length of siliconized PE tubing was used as a veno-venous shunt inserted into the abdominal vena cava of anesthetized rabbits. The PE tubing contained six cotton threads which helped to restrict blood flow through the tubing and served as a foreign, thrombogenic surface upon which a thrombus could develop. By continuously measuring blood flow through the vena cava, the rate of thrombus development can be monitored until zero flow is achieved indicating that a completely occlusive thrombus is present. The shunt can be removed making it possible to weigh the thrombus and/or determine its composition. A second shunt can be placed in the vena cava to make a second determination of time to occlusion and thrombus weight, using the data from the first shunt as an internal control standard for comparison. Reproducibility of the technique was demonstrated in a control group (n = 7) in which two successive shunts were used without an antithrombotic intervention. In studies with the first and second shunts, time to occlusion averaged 20.6+/-5.2 min and 20.2+/-5.7 min (pNS), respectively. The net thrombus weights (less the wet weight of the cotton threads) were 49.0+/-3.5 mg and 47.0+/-3.3 mg (pNS). Histologic examination of the thrombi indicated that they were largely composed of fibrin and red blood cells, consistent with the characteristics of venous thrombi. The low molecular weight heparin (LMWH) enoxaparin was used as an antithrombotic intervention to validate the model. Dose-dependent changes in time to occlusion and thrombus weight were achieved which paralleled alterations in coagulation parameters (thrombin time and activated partial thromboplastin time) and bleeding time determined with an ear bleeding technique. The veno-venous shunt model is easy to use, reproducible, and responds appropriately to an antithrombotic intervention, indicating that it should be useful for experimental evaluation of antithrombotic agents designed for venous thromboembolic disorders.

[Change of pulmonary diffusing capacity, membrane diffusing capacity and pulmonary capillary blood volume in patients with COPD and connective tissue disease at rest and post-exercise]

OBJECTIVE

Studying the changes of pulmonary diffusing capacity (DL), alveolar capillary membrane diffusing capacity (Dm) and pulmonary capillary blood volume (Vc) in patients with COPD and connective tissue disease (CTD) at rest and post-exercise; evaluating the diagnostic values of DL, Dm and Vc in early stage of pulmonary involvement of CTD.

METHOD

Spirometry was performed in the sit position. Several measurements of diffusing capacity of the lung for carbon monoxide (DLCO) were measured by single-breath method at increasing alveolar oxygen tension. The estimations of Dm and Vc were done by the method of Roughton and Forster.

RESULT

(1) In COPD group, the values of DL were lower than that of the control group at rest. The decreases were due to the reduction of Dm, but Vc were normal. In CTD group, all the value of DL, Dm and Vc were lower than that of its control group at rest. (2) COPD patients had the higher DL, Dm and Vc after the end of exercise than that of at rest. But the changes of DL Dm and Vc in COPD patients were lower compared with the control group. In contrast to the control group, DL, Dm and Vc did not increase or even decreased after the end of exercise in CTD group. (3) There was no significant differences of DL, Dm and Vc between the 7 CTD patients with normal pulmonary volume and DLCO and the control subjects at rest. But after the end of exercise, DL, Dm and Vc of CTD patients kept unchanging or even decreasing. The difference between CTD patients and its control group was found significant.

CONCLUSION

The measurements of post-exercise Dm and Vc are sensitive tests for pulmonary involvement in of CTD patients. The results are abmormal much earlier in subject with minimal dyspnea and roentgenologic change. They are useful tests for early stage CTD.

Antiproliferative effects of inducible nitric oxide synthase inhibition on decidualization in pseudopregnant rats

The aim of this study was to assess the involvement in decidual proliferation of nitric oxide (NO), a regulator of many cellular processes, that is synthesized from L-arginine by NO synthase. The investigation was conducted on pseudopregnant (PG) rats in which the decidual cell reaction, the basis for the decidualization process, was surgically induced by uterine trauma on PG Day 4. Groups of animals (n = 5) were pretreated with either 2 doses/day of N(G)-nitro-L-arginine methyl ester (L-NAME) that inhibits NO synthase, or twice daily doses of L-NAME plus L-arginine combined. Drug application times coincided with 3 hr after lights on or 3 hr before lights off. The two treatment regimens (PG Days 1-4 or 5-8) respectively preceded or followed decidual induction. Animals were sacrificed at mid-light on PG Day 9, the day of maximal growth response to the deciduogenic stimulus. Parallel, time-dependent increases in both NO synthase activity and decidual growth occurred mainly in the endometrium. L-NAME produced reductions in endometrial and myometrial growth that were reversed by the combined L-NAME plus L-arginine treatments. These inhibitory effects by L-NAME were caused by only the pretraumal (PG Days 1-4) administration. Hormonally, circulating progesterone levels were similarly affected by this early treatment and may also contribute to the reduced decidual sensitivity. In contrast, serum estradiol, along with the zinc metalloenzymes, alkaline phosphatase and the matrix metalloproteinases--prominent decidualization biomarkers--were all unaffected by either the pre- or post-decidual induction dosings. The study demonstrates that inducible NO synthase/endogenous NO may physiologically participate in uterine metabolism during the decidual cell reaction. Moreover, by virtue of L-NAME inhibition of the decidual response, it appears that NO synthase/NO may influence decidual growth either by directly increasing uterine sensitivity to the deciduogenic stimulus or by indirectly affecting endometrial vascularity and subsequent availability of decidual metabolites.

Functional microdomains in G-protein-coupled receptors. The conserved arginine-cage motif in the gonadotropin-releasing hormone receptor

An Arg present in the third transmembrane domain of all rhodopsin-like G-protein-coupled receptors is required for efficient signal transduction. Mutation of this Arg in the gonadotropin-releasing hormone receptor to Gln, His, or Lys abolished or severely impaired agonist-stimulated inositol phosphate generation, consistent with Arg having a role in receptor activation. To investigate the contribution of the surrounding structural domain in the actions of the conserved Arg, an integrated microdomain modeling and mutagenesis approach has been utilized. Two conserved residues that constrain the Arg side chain to a limited number of conformations have been identified. In the inactive wild-type receptor, the Arg side chain is proposed to form an ionic interaction with Asp3.49(138). Experimental results for the Asp3. 49(138) --> Asn mutant receptor show a modestly enhanced receptor efficiency, consistent with the hypothesis that weakening the Asp3. 49(138)-Arg3.50(139) interaction by protonation of the Asp or by the mutation to Asn favors activation. With activation, the Asp3. 49(138)-Arg3.50(139) ionic bond would break, and the unrestrained Arg would be prevented from orienting itself toward the water phase by a steric clash with Ile3.54(143). The mutation Ile3.54(143) --> Ala, which eliminates this clash in simulations, causes a marked reduction in measured receptor signaling efficiency, implying that solvation of Arg3.50(139) prevents it from functioning in the activation of the receptor. These data are consistent with residues Asp3.49(138) and Ile3.54(143) forming a structural motif, which helps position Arg in its appropriate inactive and active receptor conformations.

Dexamethasone-induced changes in endometrial growth and inducible nitric oxide synthase during decidualization in rats

1. The present study investigated the time-dependent inhibitory responses of endometrial growth and inducible nitric oxide synthase (iNOS) to dexamethasone during deciduoma development that was surgically induced on day 4 of pseudopregnancy (PG). 2. Groups of rats (n = 6) were subcutaneously injected with dexamethasone (1.5 mg/rat per day) for 3 days (PG days 1-3, 4-6, 7-9, 10-12 and 12-15). Rats in each group were killed on the last injection day. 3. Dexamethasone produced comparable temporal inhibitory changes in endometrial growth (wet weight, protein and DNA concentrations; P<0.0001) and in iNOS activity (130 kDa protein band), which peaked after PG days 4-6 and 7-9 pretreatments. 4. Endometrial matrix metalloproteinases (72 and 92 kDa) activity profiles displayed maximal reductions (36 and 53%, respectively) following PG days 4-6 pretreatment. Serum progesterone levels were equally (P<0.0001) but asynchronously inhibited by dexamethasone on PG days 9 and 12. 5. Dexamethasone inhibition of endometrial growth and in situ iNOS was most pronounced during decidual development (PG days 4-9). Minor reductions in these endometrial parameters occurred before deciduoma induction (PG days 1-3) and during deciduoma regression (PG days 10-15). 6. These results indicate that, in the endometrium, the iNOS/endogenous nitric oxide system may be linked to the biochemical and metabolic mechanisms responsible for the developmental responsiveness of the deciduoma to dexamethasone exposure. These time-dependent changes in endometrial growth and iNOS apparently were not mediated by progesterone.

[Effects of abnormal distribution of calcium on impairment of myocardial mechanics in the early stage of thermal injury]

OBJECTIVE

To investigate the effect of abnormal Ca2+ distribution on impairment of myocardial mechanics in the early stage of thermal injury.

METHODS

Calcium (Ca2+) changes were observed within subcellular distribution in situ in rat heart with calcium cytochemical probe and electron probe microanalysic technique. Meanwhile, myocardial mechanics and energy metabolic changes were investigated after thermal injury.

RESULTS

The results demonstrated that levels of cytoplasmic Ca2+ in cardiomyocytes increased at 1 hour, followed by enhanced mitochondrial Ca2+ at 3 hour after burn injury. Parallel to the changes in Ca2+, there were decrease of myocardial contraction, relaxation capacity and increase of ventricular wall stiffness in burned rats. A lower level of heart energy changes was observed from 6 to 12 hours, compared with control group.

CONCLUSION

The results indicate that subcellular Ca2+ abnormal distribution in myocardium caused by burn injury may be associated with rigor contraction and decreased relaxation of myocardium.

Adrenergic-dependent Effect of Adenosine-induced Ventricular Fibrillation in the Isolated Rabbit Heart

BACKGROUND: The present study examined the contributory role of endogenous catecholamines in adenosine-induced ventricular fibrillation in isolation rabbit hearts. METHODS AND RESULTS: Cardiac catecholamine depletion was induced in eleven rabbits by the administration of 6-hydroxydopamine (2 x 30 mg/kg, every 12 hours intramuscularly). Hearts were removed 24 hours later, and subjected to 12 minutes of hypoxic perfusion followed by 40 minutes of reoxygenation while heart rate was maintained with atrial pacing. One of six, and one of five hearts from 6-hydroxydopamine treated rabbits developed ventricular fibrillation during hypoxia-reoxygenation when exposed to 3,7-dimethyl-1-propargylzanthine (DMPX) (10 µM) + adenosine (ADO) (1 µM) and DMPX (10 µM) + ADO (10 µM), respectively. In hearts from a control group, not exposed to 6-hydroxydopamine, ventricular fibrillation developed in each of five (100% incidence) hearts when perfused in the presence of DMPX (10 µM) + ADO (10 µM) (P <.05). Nadolol (1 µM), a beta-adrenoceptor DMPX (10 µM) + ADO (10 µM) treated hearts (n = 6, P <.05 vs DMPX + ADO treated hearts). To ensure catecholamine depletion, spontaneously beating isolated hearts from vehicle and 6-hydroxydopamine treated rabbits were perfused under normoxic conditions while exposed to increasing concentrations of tyramine (1, 3, 10 mM) and the change in heart rate was determined. A concentration-related, positive chronotorpic response to tyramine was obtained in hearts from the vehicle treated group that was absent in hearts from 6-hydroxy-dopamine treated rabbits or hearts perfused in the presence of nadolol. CONCLUSIONS: The results demonstrate that inhibition of the cardiac adenosine A(2) receptor, unmasks an adenosine A(1) receptor profibrillatory effect that is dependent upon endogenous cardiac catecholamines and beta-adrenoreceptor activation during myocardial hypoxia-reoxygenation.

Temporal glucocorticoid treatment: modulation of periodic endometrial responses during decidualization and pregnancy in rats

The synthetic glucocorticoid, dexamethasone (Dex) was administered subcutaneously (1.5 mg/day/rat) in 3-days pretreatment regimens (Days 2-4, 4-6, 6-8, 8-10 and 10-12) to pseudopregnant rats in which decidualization was surgically induced and to pregnant rats. Variability in endometrial growth during decidualization and in the fetoplacental homeostasis of pregnancy was assessed at the end of each treatment period (Days 4, 6, 8, 10 and 12). During decidualization, endometrial growth (wet weight, protein and DNA) displayed significant (p < 0.05) time-dependent inhibitory profiles which rose steeply from Day 4 to Day 6 and declined thereafter to Day 10 in fairly well defined linear patterns. For the endometrial enzymes (isocitrate dehydrogenase, alkaline phosphatase and the matrix metalloproteinases--72 and 92 kDa), although the inhibitory patterns were inconsistent, a Days 6-8 treatment regimen seemed to be critical. By contrast Dex treatment induced progressive inhibition in serum progesterone concentrations from Day 2, to peak levels by Day 12. This indicates that time-related Dex inhibition of endometrial growth appeared not to be progesterone-mediated since the endometrial and progesterone inhibitory profiles were not in synchrony. The inhibitory effect of Dex under the pregnancy status demonstrated that birth potentials, fetal and placental weights, all had similar response patterns which rose from Day 4 to Day 8 and then underwent reductions to Day 12. Collectively, the results indicate that there was time dependency in growth inhibition by Dex at the endometrial and fetoplacental levels. Maximal sensitivity to drug exposure essentially coincided with the immediate post-traumal (decidualization) and postimplantation (pregnancy) periods.

Electrical injuries from graphite fishing rods

High tension electrical injuries have a high morbidity and mortality. Carbon fibre and graphite used in the manufacture of fishing rods gives them superconductor qualities. The resistance of a fishing rod with a carbon content of more than 70 per cent is very low, ranging from 0.9 to 10.5 k omega. Nine cases are reported, which teach an important lesson not only in the management of those severe injuries, but also in their prevention.

Tedisamil Attenuates Ventricular Fibrillation in a Conscious Canine Model of Sudden Cardiac Death

BACKGROUND: The electrophysiologic and antifibrillatory properties of tedisamil (KC-8857;3,7-di-(cyclopropylmethyl)-9,9-tetramethylene-3,7-diazabicyclo[3.3.1]-nonane dihydrochloride) were studied in a conscious canine model of sudden cardiac death. METHODS AND RESULTS: Three to five days after surgically induced myocardial infarction (2-hour occlusion of the left anterior descending coronary artery), animals were subjected to programmed electrical stimulation to identify those at risk for ischemia-induced ventricular fibrillation. Sixty minutes after tedisamil (10 mg/kg, administered orally) PES was repeated. Tedisamil increased the ventricular effective refractory period from 106 +/- 6 to 134 +/- 7 ms (P <.05) compared to placebo treatment, which did not alter the ERP (123 +/- 6 to 116 +/- 5 ms). Tedisamil prolonged the QTc interval, from a predrug value of 308 +/- 14 to 327 +/- 14 ms, postdrug. The extent of the surgically induced anterior wall myocardial infarct did not differ between groups, tedisamil, 29 +/- 2%, and placebo, 28 +/- 2% of the left ventricle. CONCLUSIONS: Tedisamil conferred protection against ischemia induced ventricular fibrillation; 7 of 10 tedisamil-treated dogs survived, compared to 4 of 14 surviving in the vehicle treated group (P <.05). Although we observed instances of vomiting and/or diarrhea in several dogs after a single oral administration of tedisamil, the data indicate that oral administration of tedisamil provides protection from ischemia-induced ventricular fibrillation in the postinfarcted conscious canine. The mechanism by which tedisamil achieves its antifibrillatory effect may be related to its ability to prolong the ERP of the ventricular myocardium without altering ventricular conduction velocity.

5-hydroxydecanoate fails to attenuate ventricular fibrillation in a conscious canine model of sudden cardiac death

The electrophysiologic and antifibrillatory properties of 5-hydroxydecanoate, a KATP channel antagonist, were studied in a conscious canine model of sudden cardiac death. After a surgically induced myocardial infarction, animals were subjected to programmed electrical stimulation to identify those at risk for sudden cardiac death. 5-Hydroxydecanoate was administered as a bolus (10 mg/kg i.v.) followed by an infusion, 10 mg/kg/h (group 1, n = 12) or 30 mg/kg bolus followed by an infusion, 30 mg/kg/h (group 2, n = 8) i.v., while vehicle treated animals received a 0.9% sodium chloride solution (group 3, n = 11). The administration of 5-hydroxydecanoate did not alter the ventricular effective refractory period or the QTc interval. Anterior wall myocardial infarcts, expressed as a percentage of the left ventricle, did not differ among groups. Infusions of 5-hydroxydecanoate did not confer significant protection from sudden cardiac death (death within 60 min of posterolateral ischemia) due to ventricular fibrillation: group 1, 50%; group 2, 38%; and group 3, 18%. The data demonstrate that a continuous infusion of 5-hydroxydecanoate (10 and 30 mg/kg/h, i.v.) does not provide protection from ischemia-induced ventricular fibrillation in the postinfarcted conscious canine.

Effect of benomyl and carbendazim on steroid and molecular mechanisms in uterine decidual growth in rats

The present study examined the influence of two benzimidazole fungicides benomyl and carbendazim (MCB), in dosages of 500 and 1000 mg kg-1 for 5 days, on the capacity of decidual growth in pseudopregnant rats. The aim of the research was to determine whether the antimitotic activity of both chemicals was being mediated by way of hormonal and molecular mechanisms at the uterine level. The results show that both fungicides produced reductions in uterine decidual weight (P < 0.01) and uterine protein content (P < 0.05). However, levels of serum estradiol and progesterone and the binding capacities of cytosol estrogen and progesterone receptors remained essentially unchanged. Subsequently, the antigrowth-antimitotic activity of benomyl and MCB, at 500 and 1000 mg kg-1 dosages, on the decidual uterus is direct, and apparently does not involve steroidal or receptor mechanisms.

Protective Effects of Ranolazine on Ventricular Fibrillation Induced by Activation of the ATP-Dependent Potassium Channel in the Rabbit Heart

BACKGROUND: The authors studied the antifibrillatory effects of the adenosine-triphosphate (ATP)-sparing metabolic modulator ranolazine in a rabbit isolated heart model in which ventricular fibrillation occurs under conditions of hypoxia/reoxygenation in the presence of the ATP-dependent potassium channel opener pinacidil. METHODS AND RESULTS: Ten minutes after ranolazine or vehicle administration, addition of pinacidil (1.25 µM) to the buffer was followed by a 12-minute hypoxic period and 40 minutes of reoxygenation. At a reduced concentration of ranolazine (10 µM), ventricular fibrillation occurred in 60% of the hearts, compared to 89% in the control group (P = NS). In contrast, only three of nine hearts (33%) treated with 20 µM ranolazine developed ventricular fibrillation (P <.05 vs vehicle). Hemodynamic parameters including coronary perfusion pressure, left ventricular developed pressure, and +/-dP/dt were not affected by the presence of ranolazine in the perfusion medium. Ranolazine did not prevent or modify the negative inotropic or coronary vasodilator actions of pinacidil, suggesting a mechanism of action independent of potassium channel antagonism. CONCLUSIONS: Ranolazine significantly reduced the incidence of ventricular fibrillation in the hypoxic/reoxygenated heart exposed to the ATP-dependent potassium channel opener, pinacidil. The reported ability of ranolazine to prevent the decrease in cellular ATP during periods of a reduced oxygen supply may account for its observed antifibrillatory action. By maintaining intracellular ATP, ranolazine may modulate or prevent further opening of the ATP-dependent potassium channel in response to hypoxia and/or pinacidil.

Effects of tedisamil (KC-8857) on cardiac electrophysiology and ventricular fibrillation in the rabbit isolated heart

1. The direct cardiac electrophysiological and antifibrillatory actions of tedisamil (KC-8857) were studied in rabbit isolated hearts. 2. Tedisamil (1, 3, and 10 microM), prolonged the ventricular effective refractory period (VRP) from 120 +/- 18 ms (baseline) to 155 +/- 19, 171 +/- 20, and 205 +/- 14 ms, respectively. Three groups of isolated hearts (n = 6 each) were used to test the antifibrillatory action of tedisamil. Hearts were perfused with 1.25 microM pinacidil, a KATP channel activator. Hearts were subjected to hypoxia for 12 min followed by 40 min of reoxygenation. Ventricular fibrillation (VF) developed during hypoxia and reoxygenation in both the control and 1 microM tedisamil-treated groups (5/6 and 4/6, respectively). Tedisamil (3 microM) reduced the incidence of VF (0/6, P = 0.007 vs. control). 3. In a separate group of hearts, VF was initiated by electrical stimulation. The administration of 0.3 ml of 10 mM tedisamil, via the aortic cannula, terminated VF in all hearts, converting them to normal sinus rhythm. 4. Tedisamil (3 microM) reversed pinacidil-induced negative inotropic effects in rabbit isolated atrial muscle which were equilibrated under normoxia, as well as in atrial muscle subjected to hypoxia and reoxygenation. 5. The results demonstrate a direct antifibrillatory action of tedisamil in vitro. The mechanism responsible for the observed effects may involve modulation by tedisamil of the cardiac ATP-regulated potassium channel, in addition to its antagonism of IK and Ito.