Controlling amyloid growth in multiple dimensions

The great progress made in defining the structure of protein and peptide amyloid assemblies, particularly the arrangement of peptides in β-sheets, is counterbalanced by the still poor understanding of the higher organization of β-sheets within the fibril and overall fibril/fibril associations. The assembly pathway and basis of amyloid toxicity may well depend on these higher-order structural features. For example, significant evidence points to association between sheets as the rate limiting step in fibril assembly, and a critical metal binding site has now been identified that involves residues from different individual sheets. Here we review experiments that are identifying some of the issues associated with sheet–sheet association by investigating simple model peptides derived from the central core of the Aβ peptide implicated in Alzheimer's disease. These peptides transit between fibril/ribbon/nanotube morphologies in response to assembly conditions, laying the foundation for understanding the folding landscape for these higher order assemblies, revealing potential targets for therapeutic intervention, and opening strategies for the design of highly ordered peptide self-assembled microscale morphologies.     

Maternal Adnexal Torsion in Pregnancy Is Associated with Significant Risk of Recurrence

Study ObjectivesTo investigate the phenomenon of recurrent adnexal torsion during the same pregnancy, describe its risk factors, and suggest possible management of this entity.DesignRetrospective case-control study (Canadian Task Force classification II-3).SettingGynecologic endoscopy unit in a university hospital.Patients and interventionsPregnant women with surgically proved adnexal torsion were retrospectively identified from 1993 to 2007. Details of clinical presentation, method of conception, preoperative ultrasound findings, and operative findings were analyzed.InterventionComparison of characteristics of patients with recurrent episodes of adnexal torsion during the same pregnancy vs a single episode of torsion.Measurements and Main ResultsThirty-three pregnant women with 38 episodes of adnexal torsion were included in the study. Seventeen pregnancies (51.5%) were spontaneously conceived. Twenty-eight women had a single episode of torsion, and 5 women (15.1%) had recurrent episodes of torsion during the same pregnancy. No significant differences were found between the 2 groups in age, method of conception, and gestational age at time of torsion. However, ultrasound studies demonstrated that multicystic ovaries were significantly more common in women with recurrent torsion compared with women with a single episode of torsion (80% vs 25%; p = .02). The interval between the first and second episodes of torsion ranged from 1 to 4 weeks.ConclusionPregnant women are at risk for recurrent torsion, especially when the ovaries are enlarged and ultrasound studies demonstrate multiple cysts. Cyst aspiration may prevent recurrent torsion during the same pregnancy.     

A phase I study of bexarotene, a retinoic X receptor agonist, in non-M3 acute myeloid leukemia

PURPOSE: Bexarotene is a retinoic X receptor agonist that has been shown in vitro to inhibit growth and induce differentiation of myeloid leukemic cell lines. We therefore conducted a phase I dose escalation study to assess the maximum tolerated dose, toxicities, and activity of bexarotene in patients with non-M3 acute myeloid leukemia (AML). EXPERIMENTAL DESIGN: We enrolled patients with active non-M3 AML who had either relapsed or refractory disease or were not eligible for standard cytotoxic chemotherapy. Cohorts of three to six patients received escalating doses of daily oral bexarotene ranging from 100 to 400 mg/m(2) until evidence of disease progression or unacceptable adverse events occurred. RESULTS: Twenty-seven patients, with median age of 69 years (range, 51-82 years), were treated. Twenty-four (89%) patients had undergone prior chemotherapy. At the highest dose level tested (400 mg/m(2)), three of six patients had to reduce their dose of bexarotene due to grade 3 adverse events. The maximum tolerable dose of bexarotene was determined to be 300 mg/m(2). Clinical activity was manifested by 4 (15%) patients with reduction in bone marrow blasts to 1 year while taking bexarotene. Leukemic blast differentiation was suggested by the presence of the leukemic cytogenetic abnormality in mature circulating granulocytes and the occurrence of differentiation syndrome. CONCLUSIONS: The recommended dose of bexarotene for future studies is 300 mg/m(2)/d. Bexarotene is well tolerated in patients with non-M3 AML and has evidence of antileukemic activity.     

Recombinant human chymase produced by silkworm-baculovirus expression system: its application for a chymase detection kit

Human chymase is a mast cell-derived serine proteinase, which is a non-angiotensin converting enzyme angiotensin II-generating enzyme. It appears to participate in various diseases, but it is unclear whether chymase plays major roles in physiological and pathophysiological functions in vivo. To obtain information on the physiological and pathophysiological functions of chymase and to search for diseases in which chymase participates, in the present study, we aimed at producing recombinant human chymase in large quantities and at developing an ELISA system using anti-human chymase antibodies. A recombinant human chymase was produced by a silkworm-baculovirus expression system. The recombinant chymase in active form was efficiently purified from larval hemolymph using cation-exchange and heparin column chromatography. This recombinant enzyme was enzymatically identical with native human chymase. On the other hand, the stability of the recombinant enzyme in cultured medium for mammalian cells at 37 degrees C was very high as compared with the stability of the native enzyme; 20% of the activity was maintained 120 h after addition of medium. These results indicated that the recombinant enzyme could also utilize in vitro and in vivo assay systems. We obtained several anti-chymase monoclonal antibodies by using the recombinant human chymase as antigen. These antibodies were used to construct an ELISA system for measuring the chymase concentration in blood. As a result of preliminary examination using this ELISA system, it was shown that the chymase concentration in each serum from hypertensive patients is significantly higher than in normal serum. The ELISA system will be applicable for clinical diagnosis and in vivo evaluation systems for chymase-targeting drugs.     

PERK eIF2alpha kinase regulates neonatal growth by controlling the expression of circulating insulin-like growth factor-I derived from the liver

Humans afflicted with the Wolcott-Rallison syndrome and mice deficient for PERK (pancreatic endoplasmic reticulum eIF2alpha kinase) show severe postnatal growth retardation. In mice, growth retardation in Perk-/- mutants is manifested within the first few days of neonatal development. Growth parameters of Perk-/- mice, including comparison of body weight to length and organ weights, are consistent with proportional dwarfism. Tibia growth plates exhibited a reduction in proliferative and hypertrophic chondrocytes underlying the longitudinal growth retardation. Neonatal Perk-/- deficient mice show a 75% reduction in liver IGF-I mRNA and serum IGF-I within the first week, whereas the expression of IGF-I mRNA in most other tissues is normal. Injections of IGF-I partially reversed the growth retardation of the Perk-/- mice, whereas GH had no effect. Transgenic rescue of PERK activity in the insulin- secreting beta-cells of the Perk-/- mice reversed the juvenile but not the neonatal growth retardation. We provide evidence that circulating IGF-I is derived from neonatal liver but is independent of GH at this stage. We propose that PERK is required to regulate the expression of IGF-I in the liver during the neonatal period, when IGF-I expression is GH-independent, and that the lack of this regulation results in severe neonatal growth retardation.     

Concurrent validity and classification accuracy of the Leiter and Leiter-R in low-functioning children with autism

The concurrent validity of the Leiter International Performance Scale (Leiter) and Leiter International Performance Scale–Revised (Leiter-R) was examined in a sample of children with autism who could not be assessed with more traditional measures of intelligence (e.g., the Wechsler scales). The sample consisted of 26 children ranging in age from 4 to 16 years. The correlation between the Leiter scales was high (r = .87), and there was a difference of 3.7 points between the two mean scores, nonsignificant at both statistical and clinical levels. However, significant intraindividual discrepancies were present in 10 cases, 2 of which were both large (24 and 36 points) and clinically meaningful. The mean profile of performance on Leiter-R subtests is also presented for this sample of children with autism, to allow for comparison with other groups. Based on the results of this initial evaluation, together with the current normative data, good psychometric properties, and availability of global and subtest scores with the Leiter-R, the instrument is generally recommended for use with children with autism. However, because of changes in the design of the Leiter-R, there may be greater clinical success with the original Leiter for those children who are very low functioning and severely affected, particularly younger children.     

Identification of a claims data "signature" and economic consequences for treatment-resistant depression

BACKGROUND: Major depressive disorder (MDD) is a debilitating condition with significant economic consequences. Conservative estimates indicate that between 10% and 20% of all individuals with MDD are treatment resistant. The objectives for this study were (1) to use current treatment strategies identified in the literature to evaluate the validity of studying treatment-resistant depression (TRD) using claims data and (2) to estimate cost differences between TRD-likely and TRD-unlikely patients identified by use of treatment patterns. METHOD: The data source consisted of medical, pharmaceutical, and disability claims from a Fortune 100 manufacturer for 1996 through 1998 (N = 125,242 continuously enrolled beneficiaries between the ages of 18 and 64 years). The sample included individuals with medical or disability claims for MDD (NMDD = 4186). A treatment pattern algorithm was applied to classify adult MDD patients into TRD-likely (NTRD = 487) and TRD-unlikely groups. Resource utilization and costs were compared among TRD-likely and TRD-unlikely patients and a random sample of average beneficiaries (i.e., 10% of all beneficiaries) for 1998. RESULTS: Consistent with the epidemiologic literature, the algorithm classified 12% of the MDD sample as TRD-likely. Mean annual costs were $10,954 for TRD-likely patients, $5025 for TRD-unlikely patients, and $3006 for average beneficiaries. TRD-likely patients used almost twice as many medical services as did TRD-unlikely patients and incurred significantly greater indirect costs (p < .0001). CONCLUSION: It is feasible to use an administrative dataset to develop a claim-based treatment algorithm to identify TRD-likely patients. Resource utilization by TRD-likely patients was substantial, not only for direct treatment of depression but also for treatment of comorbid medical conditions. Additionally, TRD imposed on employers substantial indirect costs resulting from high rates of depression-associated disability.