Testing for rational bubbles in a coexplosive vector autoregression

Summary Asset bubbles can be described through the rational bubble solution of the standard stock price model linking stock prices and dividends. We show how the hypothesis of a rational bubble can be tested in the context of a bivariate coexplosive vector autoregression. The methodology is illustrated using US stock prices and dividends for the period 1974–2000.     

Improving Outpatient Alcohol Treatment Systems: Integrating Focus on Motivation and Actuarial Matching

This study investigates the benefit of adding a data-driven actuarial matching system and focus on motivation to routine outpatient alcoholism treatment. The study is a two-cohort quasi-experimental study. One cohort (188 clients) were assigned to treatment based on clinician judgment. Cohort 2 (175 clients) were assigned to treatment based on actuarial matching procedures. Both cohorts were followed for 12 months. A total of 37% of Cohort 2 dropped out of treatment, compared to 52% of Cohort 1. Cohort 2 also showed greater reduction in alcohol consumption and greater improvement. Actuarial matching procedures appear to have improved treatment retention and outcome.     

Electroanatomic mapping and ablation of ventricular tachycardia associated with systemic sclerosis.

Two cases of systemic sclerosis with sustained ventricular tachycardia (VT) are presented. The first patient received hydroxychloroquine for skeletal muscle disease coexisting with cardiac involvement. In both cases, 3D-electroanatomic mapping showed low-voltage areas in the right ventricle. In the first patient the tachycardia was mapped and a protected isthmus suggesting reentry was delineated and ablated. Other substrate locations were indirectly identified by pacemapping on the right and left ventricular endocardium in the second patient. VT did not reoccur during follow-up. Radiofrequency catheter ablation is safe and effective and electroanatomic mapping may be helpful in patients with systemic sclerosis.     

Percutaneous endovascular occlusion of symptomatic coronary arteriovenous fistulas with cyanoacrylate

We describe four cases with symptomatic coronary artery fistulas that were treated primarily with endovascular cyanoacrylate embolization. Coils were also used as adjunctive embolic agents in two of these cases. All four cases showed symptomatic improvement after closure of the fistulas. Complications occurred in three cases including transient ST-segment elevation in one, symptomatic pulmonary embolization in a second, and transient pleuritic chest pain, pericarditis and acute renal failure in a third. The technical aspects of all four cases are given together with a review of the use of cyanoacrylate as an embolic material. We conclude that cyanoacrylate embolization could be considered as an alternative technique for the endovascular closure of coronary artery fistulas but must also caution that the use of this embolic agent is hazardous and should be restricted to practitioners experienced in its usage.     

A multimer model for P680, the primary electron donor of photosystem II

We consider a model of the photosystem II (PS II) reaction center in which its spectral properties result from weak (approximately 100 cm-1) excitonic interactions between the majority of reaction center chlorins. Such a model is consistent with a structure similar to that of the reaction center of purple bacteria but with a reduced coupling of the chlorophyll special pair. We find that this model is consistent with many experimental studies of PS II. The similarity in magnitude of the exciton coupling and energetic disorder in PS II results in the exciton states being structurally highly heterogeneous. This model suggests that P680, the primary electron donor of PS II, should not be considered a dimer but a multimer of several weakly coupled pigments, including the pheophytin electron acceptor. We thus conclude that even if the reaction center of PS II is structurally similar to that of purple bacteria, its spectroscopy and primary photochemistry may be very different.     

The ETO domain is necessary for the developmental abnormalities associated with AML1-ETO expression in the hematopoietic stem cell compartment in vivo

Translocation of the ETO gene on human chromosome 8 with the AML1 gene on chromosome 21 (AML1-ETO) is a recurrent cytogenetic abnormality associated with approximately 12% of acute myelogenous leukemia (AML) cases. To understand the contribution of the t(8;21) to AML, we transduced purified hematopoietic stem cells (HSC) with a retroviral vector that coexpressed AML1-ETO or just the AML1 portion (AML1d) of the translocation along with a green fluorescent protein reporter gene. Animals reconstituted with AML1-ETO-expressing cells exhibited many of the hematopoietic developmental abnormalities seen in the bone marrow of human patients with the t(8;21), although the animals did not develop acute leukemia. We noted a gradual increase in primitive myeloblasts that accounted for approximately 10% of bone marrow by 10 months posttransplant. Consistent with this observation was a 50-fold increase in myeloid colony-forming cells in vitro. In addition, accumulation of late stage metamyelocytes was observed in bone marrow along with an increase in immature eosinophil myelocytes that showed abnormal basophilic granulation. There was also a gradual increase in both the frequency and absolute number of AML1-ETO-expressing HSC so that by 10 months posttransplant, there were 29-fold greater HSC numbers than in transplant-matched control mice. These phenotypes were not observed in animals reconstituted with cells expressing only the DNA-binding domain of AML1, suggesting that the ETO domain is necessary to establish the developmental abnormalities associated with AML1-ETO expression in HSC.