Recombinant TFPI and variants:potential implications in the treatment of cardiovascular disorders

The Kunitz-type proteinase inhibitor, tissue factor pathway inhibitor (TFPI), is the only endogenous inhibitor of the tissue factor (TF)-mediated coagulation pathway that plays a dominant role in normal haemostasis. TFPI exerts its action by binding to factor Xa (FXa) forming a TFPI-FXa complex that then, in a second step, binds and effectively inhibits the TF-factor VIIa (FVIIa) complex. Both full-length TFPI and chemically modified forms (e.g., truncated, glycosylated or phosphorylated TFPI variants) exert various pharmacological effects. The anticoagulant and antiplatelet actions of TFPI, its potency in inhibiting thrombin and FXa generation, as well as its favourable antithrombotic effectiveness seen in different animal models of venous and arterial thrombosis make this inhibitor a promising agent that could be potentially useful in several clinical indications. The inhibitory action of TFPI is accelerated by heparin. Heparin, as well as low molecular weight heparin (LMWH) derivatives, release TFPI from the vascular endothelium, an effect which seems to contribute mainly to the antithrombotic effectiveness of these drugs. The clinical relevance of TFPI is still undefined. Based on the beneficial actions in animal studies, as well as on the results obtained in first clinical investigations, TFPI is expected to be effective in the treatment of various diseases, such as disseminated intravascular coagulation, sepsis, coronary syndromes, stroke and acute respiratory distress syndrome (ARD). Further clinical trials should clarify the role of TFPI and more importantly define its potential usefulness as a prophylactic and/or therapeutic agent.

Incisional hernia after periacetabular osteotomy

The incidence of incisional abdominal hernias, an unreported complication after a Bernese periacetabular osteotomy, was evaluated. Two cases of an incisional hernia above the iliac crest were detected in a series of 950 cases since 1984. Although the incidence has been small, risk factors may be obesity, weak abdominal muscle strength, or increased abdominal pressure attributable to chronic coughing or obstipation. The surgeon should recognize the importance of restoring continuity of the abdominal fascia in patients with such factors.

Association between a serotonin transporter promoter region polymorphism and mood response during tryptophan depletion

This study investigated the relationship between depressive symptom response during tryptophan (TRP) depletion and a functional polymorphism of the promoter region of the serotonin (5-HT) transporter gene (SLC6A4).(1) Forty-three subjects in remission from a major depressive episode who underwent TRP depletion were genotyped. DNA was extracted from blood lymphocytes or from cheek cells.(2) The two common alleles are designated long (l) and short (s). Depressive symptoms were measured with the 25-item Hamilton Depression Rating Scale (HDRS).(3) There was a significant association between the l homozygous genotype and the depressive response to TRP depletion, with a significant main effect of time (F = 8.763, df = 3, 38, P = <0.001), and time x l homozygous allele interaction (F = 3.676, df = 3, 38, P = 0.02). Individuals whose genotype predicted increased 5-HT transporter activity may be more susceptible to depressive changes in response to transient 5-HT perturbations. The use of endophenotypic markers for affective disorders such as the mood response to TRP depletion may facilitate studies of complex genetic traits such as depression by decreasing its heterogeneity.

Afterload reduction in severe aortic regurgitation

This study was designed to assess the effects of afterload reduction in asymptomatic patients with severe aortic regurgitation (AR) and maintained LV function by cine-MRI. We studied 13 patients at baseline and after 0.2 mg/kg Hydralazine (I.V.). Patients were stratified according to the volumetric LV response to acute afterload reduction: Group I comprised patients with improved LV response; Group II comprised patients with unchanged or deteriorated LV response. Baseline LV function and severity of AR were not significantly different between groups. However, regurgitant fraction decreased (50 +/- 12 vs. 36 +/- 9%; P < 0.03) and cardiac output increased (4.9 +/- 1.4 vs. 7.1 +/- 1.6l/minute; P < 0,001) in Group I and remained unchanged in Group II (54 +/- 10 vs. 55 +/- 10%, P = n.s. and 5.5 +/- 1.4 vs. 6.6 +/- 0.9l/minute; P = n.s.) during maximal vasodilation. Beat-to-beat analysis revealed a decrease of left ventricular endsystolic volume index in group I (48 +/- 13 vs. 37 +/- 9 ml/beat; P < 0.05) and no change in group II (61 +/- 20 vs. 62 +/- 20 ml/beat; P = n.s.). In the natural history of chronic AR, the absence of improved LV performance during acute vasodilation using beat-to-beat analysis by MRI may identify patients with more advanced cardiac adaptation to chronic volume overload.

Tissue factor pathway inhibitor: an update of potential implications in the treatment of cardiovascular disorders

Tissue factor (TF) plays a crucial role in the pathogenesis of thrombotic, vascular and inflammatory disorders. Thus, the inhibition of this membrane protein provides a unique therapeutic approach for prophylaxis and/or treatment of various diseases. Tissue factor pathway inhibitor (TFPI), the only endogenous inhibitor of the TF/Factor VIIa (FVIIa) complex, has recently been characterised biochemically and pharmacologically. Studies in patients demonstrated that both TF and TFPI may be indicators for the course and the outcome of cardiovascular and other diseases. Based on experimental and clinical data, TFPI might become an important drug for several clinical indications. TFPI is expected to inhibit the development of post-injury intimal hyperplasia and thrombotic occlusion in atherosclerotic vessels as well as to be effective in acute coronary syndromes, such as unstable angina and myocardial infarction. Of special interest is the inhibition of TF-mediated processes in sepsis and disseminated intravascular coagulation (DIC), which are associated with the activation of various inflammatory pathways as well as of the coagulation system. A Phase II trial of the efficacy of TFPI in patients with severe sepsis showed a mortality reduction in TFPI- compared to placebo-treated patients and an improvement of organ dysfunctions. TFPI can be administered exogenously in high doses to suppress TF-mediated effects, alternatively high amounts of TFPI can be released from intravascular stores by other drugs, such as heparin and low molecular weight heparins (LMWH). Using this method high concentrations of the inhibitor are provided at sites of tissue damage and ongoing thrombosis. At present, clinical studies with TFPI are rather limited so that the clinical potential of the drug cannot be assessed properly. However, TFPI and its variants are expected to undergo further development and to find indications in various clinical states.

Localization of injected apolipophorin III in vivo - new insights into the immune activation process directed by this protein

A few years ago, it was shown that intrahemocoelic injection of the insect apolipoprotein apolipophorin III (apoLp-III) stimulates an immune response in larvae of the greater wax moth, Galleria mellonella. Since the mode of action of this activation process is unknown, we followed apoLp-III's pathway in the early phase of the immune-stimulating process, using biotin as a probe. Biotinylated apoLp-III was injected and localized using avidin-coupled horseradish peroxidase. The labeled protein was fully functional; the added amount of biotin per apoLp-III molecule used in this study only slightly decreased its ability to associate with phospholipase C-treated human low-density lipoprotein, as well as the immune-stimulating capability of apoLp-III.Gel electrophoresis with subsequent staining of biotin moieties and lipids revealed that apoLp-III undergoes lipid association in vivo within the first few minutes after injection. After two hours, no biotinylated apoLp-III was detectable in cell-free hemolymph. At this time, a subpopulation of hemocytes showed a distinct peroxidase staining. Control injections of biotinylated bovine serum albumin did not lead to similar results, giving evidence for the specificity of the phenomena observed. The results indicate that lipid association of apoLp-III occurs prior to endocytosis by immune-competent hemocytes, which is followed by the induction of a humoral immune response.

Systemic vascular effects of thrombin and thrombin receptor activating peptide in rats

The proteolytic enzyme thrombin activates its receptor by cleavage of a peptide from the extracellular N-terminus. The newly generated N-terminus acts as a tethered ligand to activate the receptor. Receptor-mediated cellular effects of thrombin can be mimicked by synthetic peptides, which correspond to the amino acid sequence of the newly formed N-terminus. The aim of the present study was to investigate vascular effects of thrombin and the thrombin receptor activating peptide (TRAP: SFLLRN) in vitro and in vivo in rats. In precontracted rat aortic rings, both thrombin (0.3, 1, 3 U/ml) and TRAP (1, 3, 10, 20, 40 microM) induced endothelium-dependent relaxant responses. In anaesthetized rats, the mean arterial blood pressure (MAP) was measured continuously in the carotid artery by a pressure transducer. Thrombin and TRAP were administered as intravenous bolus injection via the femoral vein. Thrombin at doses of 3-100 U/kg, as well as TRAP at doses of 0.1-0.6 mg/kg i.v., caused a reversible decrease in MAP. Administration of TRAP at doses of 0.3 and 0.6 mg/kg led to a triphasic response in most of the animals treated (50% and 75%, respectively), i.e. a short drop of MAP was followed by an increase and finally a longer lasting decrease in MAP. Pretreatment with the nitric oxide (NO)-synthase inhibitor N(G)-nitro-L-arginine-methylester (L-NAME) suppressed the dose-dependent vasodilator effects of thrombin. Heparin and hirudin also inhibited the hypotensive response to thrombin. The TRAP-induced triphasic reaction on MAP was not affected by the serotonin antagonists ketanserin and tropisetron, as well as the aminopeptidase inhibitor amastatin. Pretreatment with L-NAME led to an inhibition of hypotension induced by TRAP at 0.1 mg/kg, as well as of the initial transient fall in blood pressure at doses of 0.3 and 0.6 mg/kg. The studies suggest that the thrombin- and TRAP-induced vasodilation in vitro and in vivo is in part due to the release of endothelial NO. In the blood pressure response to TRAP, additional effects seem to be involved.

Solutions to health care waste: life-cycle thinking and "green" purchasing

Health care waste treatment is linked to bioaccumulative toxic substances, such as mercury and dioxins, which suggests the need for a new approach to product selection. To address environmental issues proactively, all stages of the product life cycle should be considered during material selection. The purchasing mechanism is a promising channel for action that can be used to promote the use of environmentally preferable products in the health care industry; health care facilities can improve environmental performance and still decrease costs. Tools that focus on environmentally preferable purchasing are now emerging for the health care industry. These tools can help hospitals select products that create the least amount of environmental pollution. Environmental performance should be incorporated into the evolving definition of quality for health care.

The configurational stability of an enantioenriched alpha-thiobenzyllithium derivative and the stereochemical course of its electrophilic substitution reactions; synthesis of enantiomerically pure, tertiary benzylic thiols

The lithium compound (S)-7, formed by deprotonation of the (S)-S-1-phenylethyl thiocarbamate (S)-10, is configurationally stable at -70 degrees C. Even at elevated temperatures it racemizes only very slowly. It represents the first essentially enantiopure alpha-thiocarbanion derivative and can be utilized in asymmetric synthesis. Most electrophiles (except proton acids) add to (S)-7 with complete stereoinversion. Cleavage of the substitution products leads to practically enantiopure, tertiary 1-phenylalkanethiols.

Pharmaka mit Wirkung auf das kardiovaskuläre System

Neben ihren Wirkungen auf das Herz-Kreislauf-System beeinflussen kardiovaskuläre Pharmaka zahlreiche andere Strukturen des menschlichen Organismus, was sowohl in erwünschten als auch unerwünschten Nebenwirkungen, unter anderem auf die Hämostase, resultieren kann. So können, aufgrund der Interaktionen des Renin-Angiotensin-Systems mit dem Kallikrein-Kinin- und dem Fibrinolysesystem, Inhibitoren des Angiotensin-Converting-Enzyms (ACE) bzw. Angiotensin-II-Rezeptor-Antagonisten profibrinolytische und antithrombotische Effekte hervorrufen. Unter den Pharmaka, die zur Therapie der koronaren Herzkrankheit eingesetzt werden, sind vor allem vasoaktive Substanzen wie Nitroverbindungen von Interesse, da sie die Plättchenaggregation hemmen. Die zur Senkung des Lipidspiegels verwendeten HMG-CoA-Reduktase-Inhibitoren oder Statine haben antithrombotische Eigenschaften, die auf spezifischen, nicht mit der Lipidsenkung verbundenen Wirkungsmechanismen beruhen. Hinsichtlich unerwünschter Nebenwirkungen kardiovaskulärer Pharmaka auf die Hämostase ist nur wenig bekannt. Bei Anwendung von ACE-Inhibitoren und vasoaktiven Substanzen wurden vereinzelt Blutungen, insbesondere im Bereich des Magen-Darm-Traktes, beobachtet. Einige Diuretika und β-Blocker können den Fettstoffwechsel mit Auftreten einer Hyperlipidämie beeinflussen.

Urea utilization in the phototrophic bacterium Rhodobacter capsulatus is regulated by the transcriptional activator NtrC

The phototrophic nonsulfur purple bacterium Rhodobacter capsulatus can use urea as a sole source of nitrogen. Three transposon Tn5-induced mutations (Xan-9, Xan-10, and Xan-19), which led to a Ure(-) phenotype, were mapped to the ureF and ureC genes, whereas two other Tn5 insertions (Xan-20 and Xan-22) were located within the ntrC and ntrB genes, respectively. As in Klebsiella aerogenes and other bacteria, the genes encoding urease (ureABC) and the genes required for assembly of the nickel metallocenter (ureD and ureEFG) are clustered in R. capsulatus (ureDABC-orf136-ureEFG). No homologues of Orf136 were found in the databases, and mutational analysis demonstrated that orf136 is not essential for urease activity or growth on urea. Analysis of a ureDA-lacZ fusion showed that maximum expression of the ure genes occurred under nitrogen-limiting conditions (e.g., serine or urea as the sole nitrogen source), but ure gene expression was not substrate (urea) inducible. Expression of the ure genes was strictly dependent on NtrC, whereas sigma(54) was not essential for urease activity. Expression of the ure genes was lower (by a factor of 3.5) in the presence of ammonium than under nitrogen-limiting conditions, but significant transcription was also observed in the presence of ammonium, approximately 10-fold higher than in an ntrC mutant background. Thus, ure gene expression in the presence of ammonium also requires NtrC. Footprint analyses demonstrated binding of NtrC to tandem binding sites upstream of the ureD promoter. Phosphorylation of NtrC increased DNA binding by at least eightfold. Although urea is effectively used as a nitrogen source in an NtrC-dependent manner, nitrogenase activity was not repressed by urea.

A synthetic inhibitor of factor Xa, DX-9065a, reduces proliferation of vascular smooth muscle cells in vivo in rats

The effect of factor Xa inactivation on the proliferation of vascular smooth muscle cells in vivo was investigated in an experimental restenosis model in rats by using the direct factor Xa inhibitor DX-9065a. In the left common carotid artery, an injury of the vascular endothelium was produced by four external vessel clamps for 60 minutes. After 14 days, 3H-labeled methyl thymidine and 5-bromo-2'-deoxyuridine, respectively, were injected intraperitoneally. After 24 hours, both the left (damaged) and right (nondamaged) carotid arteries were removed, and the incorporation of 3H-methyl thymidine/microg protein was determined. For morphological analysis, the cells were labeled with hematoxylin as well as 5-bromo-2'-deoxyuridine. Stained vascular smooth muscle cell nuclei were counted, and the proliferation index (percentage of 5-bromo-2'-deoxyuridine-positive nuclei to total nuclei stained with hematoxylin) was determined. An external damage of the carotid artery induced proliferation of vascular smooth muscle cells and formation of a neointima within 2 weeks after vessel injury. As compared with control animals, single subcutaneous injection of DX-9065a (2.5, 5, and 10 mg/kg) given 30 minutes before vessel injury significantly reduced the incorporation of 3H-methyl thymidine/microg protein and the total cell number, as well as the proliferation index. The antiproliferative action of DX-9065a was not dose dependent in the range from 2.5 to 10 mg/kg s.c. A combination of bolus injection (5 mg/kg s.c.) with continuous administration (5 mg/kg/d s.c. for 7 and 14 days, respectively) did not increase the antiproliferative effect of DX-9065a. The results indicate a role of factor Xa in the complex pathogenesis of restenosis and the usefulness of a highly effective and selective inhibitor of factor Xa to inhibit proliferative processes.

Inactivation of factor Xa by the synthetic inhibitor DX-9065a causes strong anticoagulant and antiplatelet actions in human blood

In an in vitro study, anticoagulant and antiplatelet effects of the synthetic, direct factor Xa inhibitor DX-9065a, (+)-2S-2-[4-[[(3S)-1-acetimidoyl-3-pyrrolidinyl]oxy]phenyl]-3-[7-a midino-2-naphthyl]propanoic acid hydrochloride pentahydrate, which shows a high affinity and selectivity towards the enzyme, were investigated. Anticoagulant actions of DX-9065a were studied in human plasma using global clotting assays [prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT) and Heptest]. The effect on thrombin generation was measured in whole blood by determining the plasma concentration of prothrombin fragment F1.2. The influence on agonist-induced platelet activation in whole blood was studied using flow cytometric analysis. DX-9065a caused a concentration-dependent prolongation of clotting times in the PT and APTT assay, whereas Heptest was less affected and TT was not influenced. Furthermore, DX-9065a strongly inhibited the generation of thrombin without and after coagulation activation. The factor Xa inhibitor did not affect platelet activation mediated by either thrombin receptor activating peptide, arachidonic acid or y-thrombin, but prevented tissue factor- and factor Xa-induced activation of platelets in a concentration-dependent manner. Inactivation of factor Xa by a highly effective and selective inhibitor, and the resulting inhibition of thrombin generation leads to strong anticoagulant and antiplatelet actions. The interference with the coagulation system at the early level of factor Xa is expected to be an effective approach for a successful anticoagulant/antithrombotic therapy.

Preclinical biochemistry and pharmacology of low molecular weight heparins in vivo--studies of venous and arterial thrombosis

Low molecular weight heparins (LMWHs) are effective agents in both venous and arterial thrombosis. Extensive preclinical studies in various animal models show that there are substantial differences in antithrombotic efficacy between LMWHs, and that the relative efficacy of individual agents depends on the thrombogenic stimulus used. Relative efficacy cannot be predicted on the basis of molecular weight, nor on the basis of anti-factor Xa or anti-factor IIa potency. This suggests that other mechanisms of action, e.g., the release of tissue factor pathway inhibitor (which differs among the LMWHs), are important. Data obtained with a specific LMWH cannot be extrapolated to other compounds within the same class and their substitution in the clinical setting is, therefore, inappropriate.

Ultrasonography in the diagnosis of transient synovitis of the hip and Legg-Calvé-Perthes disease

Ultrasonography was used to establish the diagnosis of transient hip synovitis and the onset of Legg-Calvé-Perthes disease. A total of 115 patients presenting with 119 painful hips and the preliminary diagnosis of transient hip synovitis were reviewed. Hip effusion, resulting in capsular distension, was documented accurately with ultrasound. In nine patients, capsular distension persisted longer than 6 weeks and was associated with the onset of Legg-Calvé-Perthes disease.

Identification of a gene encoding the pyruvate decarboxylase gene regulator CaPdc2p from Candida albicans

In a screen for Candida albicans genes encoding transactivating proteins, a pyruvate decarboxylase (EC 4.1.1.1.) regulator gene was isolated. An open reading frame (ORF) of 2511 bp was identified encoding a predicted protein of 836 amino acids with a molecular weight of 94.4 kDa. The protein showed glutamine- and proline-rich stretches typical for transcriptional activators. The amino acid sequence comparisons between CaPdc2p of C. albicans and both Pdc2p of Saccharomyces cerevisiae and Rag3p of Kluyveromyces lactis, revealed similarities of 40% and 39%, respectively. The CaPDC2 gene was localized on chromosome 1. Southern blot analysis indicated that CaPDC2 might be a single copy gene. The growth defect of a S. cerevisiae pdc2 delta mutant on glucose was compensated by transformation of the C. albicans CaPDC2 gene.

[Diagnosis, therapy and endocrinologic parameters of persistent follicles in mares in comparison with preovulatory follicles]

During the 1997 breeding season persistent follicles were diagnosed in 17 mares. In 16 of these mares a total of 17 follicles were transabdominally punctured and the steroids oestradiol, progesterone and testosterone were measured in the follicular fluid and in blood serum. In ten mares serving as a control group preovulatory follicles were punctured. The follicular fluid of the persistent follicles revealed a very high variability of the steroid concentrations. Depending on the steroid ratio within the follicles, eight follicles were rated as being intact, three follicles were undergoing atresia and five follicles were luteinized. Because of the high oestradiol levels of the follicular fluid within the control group, all of these follicles were considered to be intact. In both groups, no correlation of the steroid concentration between serum and follicular fluid was detectable. This fact argues against a passive diffusion of the steroids through the follicular wall. By puncturing the persistent follicles it was possible to bring the affected mares back into a physiological oestrus cycle within a normal dioestrus period.

[Ischemic complications in aortic dissection--percutaneous treatment with balloon fenestration and stent implantation]

PURPOSE

To describe principles and results of percutaneous treatment of ischemic complications of aortic dissection.

MATERIALS AND METHODS

In five cases (four patients) aortic dissection was clinically complicated by renal (n = 4), iliofemoral (n = 2) or mesenterial ischemia (n = 1). After evaluation by means of computed tomography, angiography, and manometry, treatment consisted of balloon fenestration of the intimal flap, stent placement or both.

RESULTS

Eleven of 25 vascular beds were classified as ischemic. Treatment consisted of 11 balloon fenestration procedures in 3 patients, in one case supported by stent placement across the dissection membrane. Stents were placed in five renal arteries, one stent was placed in the true lumen of the aorta. One iliac artery was treated with balloon dilatation. One renal artery dissection became symptomatic after balloon fenestration and was treated successfully by stent placement. In all cases ischemia was resolved by endovascular treatment. All patients had persistent relief of symptoms. Mean follow-up time is 5.8 months.

CONCLUSION

Ischemic complications of aortic dissection can be effectively and safely treated with stent placement and balloon fenestration.