Preferences and illusions in quantified spatial relational reasoning

The following presents the results of an investigation of strategies and preferences in human reasoning about quantified spatial relational assertions. An empirical study revealed a clear preference effect for specific models: The initially constructed model depends on the number of mental model operations. The participants' strategies can be classified as follows: (1) Models with grouped elements are preferred; (2) Models are constructed according to a parsimonious representation strategy. Systematic reasoning errors and illusions can be identified with logical connectors (AND: 86 % valid initial models; XOR: 47 %; Wilcoxon z = 4.6; p < .001). Error rates were smallest when using two universal quantifiers (All-All), they increase significantly when using one (Some-All; All-Some) and again using none (Some-Some) (Page's L = 436; z = 3.40 p < .001). Although the different assertions allowed for multiple situations, the difficulty can be traced back to specific quantifiers and logical connectors.

Cross-Cultural Preferences in Spatial Reasoning

Abstract

How do people reason about spatial relations? Do people with different cultural backgrounds differ in how they reason about space? The aim of our cross-cultural study on spatial reasoning is to strengthen this link between spatial cognition and culture. We conducted two reasoning experiments, one in Germany and one in Mongolia. Topological relations, such as “A overlaps B” or “B lies within C”, were presented to the participants as premises and they had to find a conclusion that was consistent with the premises (“What is the relation between A and C?”). The problem description allowed multiple possible “conclusions”. Our results, however, indicate that the participants had strong preferences: They consistently preferred one of the possible conclusions and neglected other conclusions, although they were also logically consistent with the premises. The preferred and neglected conclusions were similar in Germany and Mongolia. We argue that the preferences are caused by universal cognitive principles that work the same way in the western culture and Mongolia.

Virologic and clinical outcomes of hepatitis B virus infection in HIV-HBV coinfected transplant recipients

Liver transplantation (LT) is the treatment of choice for end-stage liver disease, but is controversial in patients with human immunodeficiency virus (HIV) infection. Using a prospective cohort of HIV-hepatitis B virus (HBV) coinfected patients transplanted between 2001-2007; outcomes including survival and HBV clinical recurrence were determined. Twenty-two coinfected patients underwent LT; 45% had detectable HBV DNA pre-LT and 72% were receiving anti-HBV drugs with efficacy against lamivudine-resistant HBV. Post-LT, all patients received hepatitis B immune globulin (HBIG) plus nucleos(t)ide analogues and remained HBsAg negative without clinical evidence of HBV recurrence, with a median follow-up 3.5 years. Low-level HBV viremia (median 108 IU/mL, range 9-789) was intermittently detected in 7/13 but not associated with HBsAg detection or ALT elevation. Compared with 20 HBV monoinfected patients on similar HBV prophylaxis and median follow-up of 4.0 years, patient and graft survival were similar: 100% versus 85% in HBV mono- versus coinfected patients (p = 0.08, log rank test). LT is effective for HIV-HBV coinfected patients with complications of cirrhosis, including those who are HBV DNA positive at the time of LT. Combination HBIG and antivirals is effective as prophylaxis with no clinical evidence of HBV recurrence but low-level HBV DNA is detectable in approximately 50% of recipients.

Orthogonal coordinates and hyperquantization algorithm. The NH3 and H3O+ umbrella inversion levels

In order to describe the umbrella inversion mode, which is characteristic of AB(3)-type molecules, we have introduced an alternative hyperspherical coordinate set based on a parametrization of Radau-Smith orthogonal vectors and have considered constraints which allow us to enforce the C(3v) symmetry. Structural properties and electronic energies at equilibrium and barrier configurations have been obtained at MP2 and CCSD(T) levels of theory. Energy profiles have been calculated using the CCSD(T) method with an aug-cc-pVQZ basis set. The NH(3) and H(3)O(+) umbrella inversion levels are obtained by the hyperquantization algorithm for a one-dimensional calculation, using a specially defined hyperangle as the inversion coordinate. The results are compared with experimental and theoretical energy levels, in particular, with those obtained by calculations based on two-dimensional models. The emerging picture of the umbrella inversion based on this hyperangular coordinate compares favorably with respect to the usual valence-type description.

Immune tolerance therapy utilizing factor VIII/von Willebrand factor concentrate in haemophilia A patients with high titre factor VIII inhibitors

Factor VIII (FVIII) inhibitors remain a serious complication of treatment for patients with haemophilia A. Immune tolerance induction (ITI) can eliminate inhibitors in the majority of patients, but there are major concerns related with this therapy. Investigators have raised the possibility that the use of FVIII/von Willebrand factor (FVIII/VWF) concentrates may improve the success rate of ITI and may shorten the duration of therapy necessary to attain tolerance. This retrospective study describes 25 patients at five institutions in the USA, who were treated with FVIII/VWF concentrate as part of their ITI. These were all patients who were considered poor prognosis because of clinical and laboratory characteristics, which made ITI less likely to be successful or because of a poor response to initial ITI with a monoclonal/recombinant FVIII concentrate. Overall success (complete tolerization) was 32% with another 40% attaining partial tolerization, but not complete tolerization. Of those patients attaining only partial tolerization, two patients ultimately discontinued ITI and had return of their high titre inhibitors. Eight percent of patients failed to attain either partial or complete tolerization and discontinued ITI. Another 24% are continuing with ITI but have titres of >10 BU. This study adds further retrospective data to the information regarding the use of FVIII/VWF concentrate in ITI.

Thyroid-hormone effects on putative biochemical pathways involved in UCP3 activation in rat skeletal muscle mitochondria

In vitro, uncoupling protein 3 (UCP3)-mediated uncoupling requires cofactors [e.g., superoxides, coenzyme Q (CoQ) and fatty acids (FA)] or their derivatives, but it is not yet clear whether or how such activators interact with each other under given physiological or pathophysiological conditions. Since triiodothyronine (T3) stimulates lipid metabolism, UCP3 expression and mitochondrial uncoupling, we examined its effects on some biochemical pathways that may underlie UCP3-mediated uncoupling. T3-treated rats (Hyper) showed increased mitochondrial lipid-oxidation rates, increased expression and activity of enzymes involved in lipid handling and increased mitochondrial superoxide production and CoQ levels. Despite the higher mitochondrial superoxide production in Hyper, euthyroid and hyperthyroid mitochondria showed no differences in proton-conductance when FA were chelated by bovine serum albumin. However, mitochondria from Hyper showed a palmitoyl-carnitine-induced and GDP-inhibited increased proton-conductance in the presence of carboxyatractylate. We suggest that T3 stimulates the UCP3 activity in vivo by affecting the complex network of biochemical pathways underlying the UCP3 activation.

Long-lasting antithrombotic effects of a single dose of human recombinant, active site-blocked factor VII: insights into possible mechanism(s) of action

Tissue factor (TF) is important in initiating intravascular thrombosis. We demonstrated that active-site blocked factor VII (FVIIai) inhibits intravascular thrombosis for at least 6 h following a single injection, despite FVIIai plasma half-life was approximately 45 min. The aims of the present study were: (a) to determine the duration of the antithrombotic effects of a single injection of FVIIai; and (b) to assess whether FVIIai prolonged effects can be explained by a slow dissociation rate from TF in the arterial wall. Cyclic flow variations (CFVs), obtained in stenotic rabbit carotid arteries with endothelial injury, were abolished by either FVIIai (100 micro g kg-1 min-1 for 10 min) or hirudin (1 mg kg-1). After CFVs were abolished, carotid blood flow velocity was recorded continuously for 24 h. CFVs restored in all hirudin-treated animals after 2.1 +/- 0.3 h, while they restored in only four of nine FVIIai-treated rabbits in 10.1 +/- 2.2 h. Five animals in this group did not show restoration of CFVs up to 24 h. Immunohistochemistry revealed that FVIIai was still bound to the arterial wall 24 h following its administration, despite at this time FVIIai plasma levels were undetectable. Prothrombin time and partial thromboplastin time did not change significantly. FVIIai exerts potent, long-lasting antithrombotic effects without affecting systemic hemostatic parameters; a possible mechanism is a slow dissociation rate of FVIIai from TF. These proprieties make FVIIai particularly attractive as an antithrombotic intervention.

Expression of exogenous tissue factor pathway inhibitor in vivo suppresses thrombus formation in injured rabbit carotid arteries

OBJECTIVES

The aim of the present study was to test the hypothesis that retrovirus-mediated in vivo tissue factor pathway inhibitor (TFPI) gene transfer to the arterial wall would efficiently inhibit thrombosis without causing significant changes in systemic hemostatic variables.

BACKGROUND

Acute coronary syndromes (unstable angina and acute myocardial infarction) are usually caused by atherosclerotic plaque rupture, with consequent activation of the coagulation cascade and circulating platelets. Tissue factor (TF) exposure represents an early event in this pathophysiologic sequence, leading to activation of the extrinsic coagulation pathway and thrombin formation. Tissue factor pathway inhibitor is a naturally occurring inhibitor of the extrinsic pathway.

METHODS

In the present study, the gene coding for rabbit TFPI was inserted in a retroviral vector under control of a tetracycline-inducible promoter. Replication-defective, infectious, recombinant retroviruses were used to transfect rabbit carotid arteries with either TFPI or a reporter gene--green fluorescent protein (GFP).

RESULTS

Retroviral-mediated arterial gene transfer of TFPI resulted in potent inhibition of intravascular thrombus formation in stenotic and injured rabbit carotid arteries, whereas transfection of the contralateral carotid artery with GFP had no effect on thrombosis. No significant changes in systemic hemostatic variables (prothrombin time and partial thromboplastin time) were observed when thrombosis was inhibited.

CONCLUSIONS

These data suggest that retroviral-mediated transfection of the arterial wall with TFPI might represent an attractive approach for the treatment of thrombotic disorders.

Fatty acid chain elongation synthesis in eel (Anguilla anguilla) liver mitochondria

The properties of fatty acid chain elongation synthesis have been investigated in liver mitochondria of the European eel (Anguilla anguilla). The incorporation of [1-(14)C]acetyl-CoA into fatty acids shows a specific activity of 0.43+/-0.05 nmol/min x mg protein (n=6), which is more than twice higher than that previously reported in rat liver mitochondria. Label incorporation into fatty acids was, in mitochondria disrupted by freezing and thawing, much higher than in intact organelles thus suggesting a probable localization of this pathway inside mitochondria. Only a negligible acetyl-CoA incorporation into fatty acids occurs in the absence of ATP, Mg2+ or reduced pyridine nucleotides; NADH alone seems to be as effective as NADH + NADPH as a hydrogen donor for the reducing steps. CoASH, without effect up to 10 microM, showed a strong inhibition at higher concentrations. From the ratio of total radioactivity and radioactivity in carboxyl carbon it can be inferred that in eel-liver mitochondria only chain elongation of preexisting fatty acids occurs. A significant fatty acid chain elongation activity is also present when, instead of acetyl-CoA, [2-(14)C]malonyl-CoA is used as a carbon unit donor. Moreover, the synthesized fatty acids were actively incorporated into phopholipids, mainly phosphatidylcholine, phosphatidylethanolamine and sphyngomyelin.

Efficacy of a sucrose-formulated recombinant factor VIII used for 22 surgical procedures in patients with severe haemophilia A

A sucrose-formulated recombinant FVIII (rFVIII-SF) was investigated under clinical trial conditions during surgical procedures in previously treated patients (PTPs). Fifteen PTPs with severe haemophilia A (FVIII < or = 1%) underwent 22 surgical procedures. The procedures performed cover a spectrum from minor to major surgery. Haemostatic outcome was assessed by the investigators to be excellent in 16 procedures and good in the remaining six procedures. It is concluded that rFVIII-SF is efficacious and safe in severe haemophilia A patients undergoing minor or major surgery.

Endogenous tissue factor pathway inhibitor modulates thrombus formation in an in vivo model of rabbit carotid artery stenosis and endothelial injury

BACKGROUND

Tissue factor pathway inhibitor (TFPI) is the sole known inhibitor of the extrinsic coagulation pathway of physiological importance; however, its role in modulating thrombosis in vivo is still unclear.

METHODS AND RESULTS

Intravascular thrombosis was initiated by placing an external constrictor around endothelially injured rabbit carotid arteries (n=10). Carotid blood flow velocity was measured by a Doppler flow probe. After placement of the constrictor, cyclic flow reductions (CFRs), due to recurrent thrombosis, developed at the site of stenosis. Transstenotic TFPI plasma activity was measured in blood samples before induction of CFRs and after 30, 60, and 180 minutes of CFRs. TFPI plasma activity distal to the site of thrombosis was significantly lower than the corresponding proximal values at 30, 60, and 180 minutes of CFRs. In addition, a progressive decrease in TFPI plasma activity was observed in both the proximal and the distal samples, indicating consumption of TFPI during thrombus formation. In 10 additional rabbits, CFRs were abolished by administration of aspirin (10 mg/kg). In the animals in which aspirin abolished CFRs, endogenous TFPI was depleted by a bolus of a polyclonal antibody against rabbit TFPI, and the effects on restoration of CFRs were monitored. In 5 of 6 animals in which aspirin abolished CFRs, depletion of endogenous TFPI activity caused full restoration of CFRs.

CONCLUSIONS

The data of the present study support the involvement of endogenous TFPI in the process of thrombus formation in vivo and its active role in modulating arterial thrombosis.