Physico-chemical characterization and synthesis of neuronally active alpha-conotoxins

The high speciFIcity of alpha-conotoxins for different neuronal nicotinic acetylcholine receptors makes them important probes for dissecting receptor subtype selectivity. New sequences continue to expand the diversity and utility of the pool of available alpha-conotoxins. Their identification and characterization depend on a suite of techniques with increasing emphasis on mass spectrometry and microscale chromatography, which have benefited from recent advances in resolution and capability. Rigorous physicochemical analysis together with synthetic peptide chemistry is a prerequisite for detailed conformational analysis and to provide sufficient quantities of alpha-conotoxins for activity assessment and structure-activity relationship studies.

Bioprocess-centered molecular design (BMD) for the efficient production of an interfacially active peptide

The efficient expression and purification of an interfacially active peptide (mLac21) was achieved by using bioprocess-centered molecular design (BMD), wherein key bioprocess considerations are addressed during the initial molecular biology work. The 21 amino acid mLac21 peptide sequence is derived from the lac repressor protein and is shown to have high affinity for the oil-water interface, causing a substantial reduction in interfacial tension following adsorption. The DNA coding for the peptide sequence was cloned into a modified pET-31(b) vector to permit the expression of mLac21 as a fusion to ketosteroid isomerase (KSI). Rational iterative molecular design, taking into account the need for a scaleable bioprocess flowsheet, led to a simple and efficient bioprocess yielding mLac21 at 86% purity following ion exchange chromatography (and >98% following chromatographic polishing). This case study demonstrates that it is possible to produce acceptably pure peptide for potential commodity applications using common scaleable bioprocess unit operations. Moreover, it is shown that BMD is a powerful strategy that can be deployed to reduce bioseparation complexity. (C) 2004 Wiley Periodicals, Inc.

Synthesis of homoallylic oxygenated alpha-methylene-gamma-butyrolactones: a model for preparing biologically active natural lactones

In this Letter we describe a 12% overall yield synthesis of a model for homoallylic oxygenated alpha-methylene-gamma-butyrolactones with relative stereochemistry defined by selective hydrogenation with Rh/Al(2)O(3). The synthesis was realized in 9 steps involving simple reactions. (C) 2008 Elsevier Ltd. All rights reserved.

Mechanical loading modulates glutamate receptor subunit expression in bone

The cellular mechanisms coupling mechanical loading with bone remodeling remain unclear. In the CNS, the excitatory amino acid glutamate (Glu) serves as a potent neurotransmitter exerting its effects via various membrane Glu receptors (GluR). Nerves containing Glu exist close to bone cells expressing functional GluRs. Demonstration of a mechanically sensitive glutamate/aspartate transporter protein and the ability of glutamate to stimulate bone resorption in vitro suggest a role for glutamate linking mechanical load and bone remodeling. We used immunohistochemical techniques to identify the expression of N-methyl-D-aspartate acid (NMDA) and non-NMDA (AMPA or kainate) ionotropic GluR subunits on bone cells in vivo. In bone sections from young adult rats, osteoclasts expressed numerous GluR subunits including AMPA (GluR2/3 and GluR4), kainic acid (GluR567) and NMDA (NMDAR2A, NMDAR2B and NMDAR2C) receptor subtypes. Bone lining cells demonstrated immunoexpression for NMDAR2A, NMDAR2B, NMDAR2C, GluR567, GluR23, GuR2 and GluR4 subunits. Immunoexpression was not evident on osteocytes, chondrocytes or vascular channels. To investigate the effects of mechanical loading on GluR expression, we used a Materials Testing System (MTS) to apply 10 N sinusoidal axial compressive loads percutaneously to the right limbs (radius/ulna, tibia/fibula) of rats. Each limb underwent 300-load cycles/day (cycle rate, 1 Hz) for 4 consecutive days. Contralateral, non-loaded limbs served as controls. Mechanically loaded limbs revealed a load-induced loss of immunoexpression for GluR2/3, GluR4, GluR567 and NMDAR2A on osteoclasts and NMDAR2A, NMDAR2B, GluR2/3 and GluR4 on bone lining cells. Both neonatal rabbit and rat osteoclasts were cultured on bone slices to investigate the effect of the NMDA receptor antagonist, MK801, and the AMPA/kainic acid receptor antagonist, NBQX, on osteoclast resorptive activity in vitro. The inhibition of resorptive function seen suggested that both NMDAR and kainic acid receptor function are required for normal osteoclast function. While the exact role of ionotropic GluRs in skeletal tissue remains unclear, the modulation of GluR subunit expression by mechanical loading lends further support for participation of Glu as a mechanical loading effector. These ionotropic receptors appear to be functionally relevant to normal osteoclast resorptive activity. (C) 2005 Elsevier Inc. All rights reserved.

Dyslipidemia in a Cohort of HIV-infected Latin American Children Receiving Highly Active Antiretroviral Therapy*

In order to describe the prevalence of hypercholesterolemia and hypertriglyceridemia in a cohort of HIV-infected children and adolescents in Latin America and to determine associations with highly active antiretroviral therapy (HAART), we performed this cross-sectional analysis within the NICHD International Site Development Initiative pediatric cohort study. Eligible children had to be at least 2 years of age and be on HAART. Among the 477 eligible HIV-infected youth, 98 (20.5%) had hypercholesterolemia and 140 (29.4%) had hypertriglyceridemia. In multivariable analyses, children receiving protease inhibitor (PI)-containing HAART were at increased risk for hypercholesterolemia [adjusted odds ratio (AOR) = 2.7, 95% confidence interval (CI) 1.3-5.6] and hypertriglyceridemia (AOR = 3.5, 95% CI 1.9-6.4) compared with children receiving non-nucleoside reverse transcriptase inhibitor (NNRTI)-containing HAART. In conclusion, HIV-infected youth receiving PI-containing HAART in this Latin American cohort were at increased risk for hypercholesterolemia and hypertriglyceridemia compared with those receiving NNRTI-containing HAART.

Viral Load Predicts New World Health Organization Stage 3 and 4 Events in HIV-Infected Children Receiving Highly Active Antiretroviral Therapy, Independent of CD4 T Lymphocyte Value

Background. Many resource-limited countries rely on clinical and immunological monitoring without routine virological monitoring for human immunodeficiency virus (HIV)-infected children receiving highly active antiretroviral therapy (HAART). We assessed whether HIV load had independent predictive value in the presence of immunological and clinical data for the occurrence of new World Health Organization (WHO) stage 3 or 4 events (hereafter, WHO events) among HIV-infected children receiving HAART in Latin America. Methods. The NISDI (Eunice Kennedy Shriver National Institute of Child Health and Human Development International Site Development Initiative) Pediatric Protocol is an observational cohort study designed to describe HIV-related outcomes among infected children. Eligibility criteria for this analysis included perinatal infection, age ! 15 years, and continuous HAART for >= 6 months. Cox proportional hazards modeling was used to assess time to new WHO events as a function of immunological status, viral load, hemoglobin level, and potential confounding variables; laboratory tests repeated during the study were treated as time-varying predictors. Results. The mean duration of follow-up was 2.5 years; new WHO events occurred in 92 (15.8%) of 584 children. In proportional hazards modeling, most recent viral load 15000 copies/mL was associated with a nearly doubled risk of developing a WHO event (adjusted hazard ratio, 1.81; 95% confidence interval, 1.05-3.11; P = 033), even after adjustment for immunological status defined on the basis of CD4 T lymphocyte value, hemoglobin level, age, and body mass index. Conclusions. Routine virological monitoring using the WHO virological failure threshold of 5000 copies/mL adds independent predictive value to immunological and clinical assessments for identification of children receiving HAART who are at risk for significant HIV-related illness. To provide optimal care, periodic virological monitoring should be considered for all settings that provide HAART to children.

Biologically active conformer of the effector region of human C5a and modulatory effects of N-terminal receptor binding determinants on activity

A conformationally biased decapeptide agonist of human C5a (C5a(65-74)Y65,F67,P69,P71,D-Ala73 or YSFKPMPLaR) was used as a functional probe of the C5a receptor (C5aR) in order to understand the conformational features in the C-terminal effector region of C5a that are important for C5aR binding and signal transduction. YSFKPMPLaR was a potent, full agonist of C5a, but at higher concentrations had a superefficacious effect compared to the natural factor. The maximal efficacy of this analogue was 216 +/- 56% that of C5a in stimulating the release of beta-glucuronidase from human neutrophils. C5aR activation and binding curves both occurred in the same concentration range with YSFKPMPLaR, characteristics not observed with natural C5a or more conformationally flexible C-terminal agonists. YSFKPMPLaR was then used as a C-terminal effector template onto which was synthesized various C5aR binding determinants from the N-terminal core domain of the natural factor. In general, the presence of N-terminal binding determinants had little effect on either potency or binding affinity when the C-terminal effector region was presented to the C5aR in this biologically active conformation. However, one peptide, C5a(12-20)-Ahx-YSFKPMPLaR, expressed a 100-fold increase in affinity for the neutrophil C5aR and a 6-fold increase in potency relative to YSFKPMPLaR. These analyses showed that the peptides used in this study have up to 25% of the potency of C5a in human fetal artery and up to 5% of the activity of C5a in the PMN enzyme release assay.

Osteoprotegerin/RANKL system imbalance in active polyarticularonset juvenile idiopathic arthritis: a bone damage biomarker?

Objective: To evaluate the importance of receptor activator of nuclear factor kappa B (RANK)/receptor activator of nuclear factor kappa B ligand (RANKL)/osteoprotegerin (OPG) modulation in active polyarticular juvenile idiopathic arthritis (pJIA) patients with and without bone erosions. Methods: Thirty female patients (mean age 11.07 +/- 3.77 years, range 4-17 years) with active pJIA and 30 healthy gender-and age-matched controls were consecutively selected for this study. All involved articulations were assessed by X-ray and examined for the presence of bone erosions. The serum levels of RANKL and OPG were measured using an enzyme-linked immunosorbent assay (ELISA). Results: Patients with active pJIA had higher levels of serum RANKL than controls [2.90 (0.1-37.4) vs. 0.25 (0.1-5.7) pg/mL, p=0.007] and a lower OPG/RANKL ratio [21.25 (1.8-897.6) vs. 347.5 (9-947.8), p=0.005]. However, levels of OPG were comparable in both groups [55.24 (28.34-89.76) vs. 64.42 (30.68-111.28) pg/mL, p=0.255]. Higher levels of serum RANKL and a lower OPG/RANKL ratio were also observed in active pJIA patients with bone erosions compared to controls [3.49 (0.1-37.4) vs. 0.25 (0.1-5.7) pg/mL, p=0.0115 and 14.3 (1.8-897.6) vs. 347.5 (9-947.8), p=0.016]. However, RANKL levels and OPG/RANKL ratio were similar in pJIA patients without bone erosion and controls [1.75 (0.1-10.9) vs. 0.25 (0.1-5.7) pg/mL, p=0.055 and 29.2 (3.3-756.8) vs. 347.5 (9-947.8), p=0.281]. Conclusion: These data suggest that active pJIA with bone erosions is associated with high serum levels of RANKL and a low OPG/RANKL ratio, indicating that these alterations may reflect bone damage in this disease.

The uncharged surface features surrounding the active site of Escherichia coli DsbA are conserved and are implicated in peptide binding

DsbA is a protein-folding catalyst from the periplasm of Escherichia coli that interacts with newly translocated polypeptide substrate and catalyzes the formation of disulfide bonds in these secreted proteins. The precise nature of the interaction between DsbA and unfolded substrate is not known. Here, we give a detailed analysis of the DsbA crystal structure, now refined to 1.7 Angstrom, and present a proposal for its interaction with peptide. The crystal structure of DsbA implies flexibility between the thioredoxin and helical domains that may be an important feature for the disulfide transfer reaction. A hinge point for domain motion is identified-the typo IV beta-turn Phe 63-Met 64-Gly 65-Gly 66, which connects the two domains. Three unique features on the active site surface of the DsbA molecule-a groove, hydrophobic pocket, and hydrophobic patch-form an extensive uncharged surface surrounding the active-sits disulfide. Residues that contribute to these surface features are shown to be generally conserved in eight DsbA homologues. Furthermore, the residues immediately surrounding the active-site disulfide are uncharged in all nine DsbA proteins. A model for DsbA-peptide interaction has been derived from the structure of a human thioredoxin:peptide complex. This shows that peptide could interact with DsbA in a manner similar to that with thioredoxin. The active-site disulfide and all three surrounding uncharged surface features of DsbA could, in principle, participate in the binding or stabilization of peptide.

Double-blind, Randomized placebo controlled trial of fulvestrant compared with exemestane after prior nonsteroidal aromatase inhibitor therapy in postmenopausal women with hormone receptor-positive, advanced breast cancer: Results from EFECT

Purpose The third-generation nonsteroidal aromatase inhibitors (AIs) are increasingly used as adjuvant and first-line advanced therapy for postmenopausal, hormone receptor-positive (HR +) breast cancer. Because many patients subsequently experience progression or relapse, it is important to identify agents with efficacy after AI failure. Materials and Methods Evaluation of Faslodex versus Exemestane Clinical Trial (EFECT) is a randomized, double-blind, placebo controlled, multicenter phase III trial of fulvestrant versus exemestane in postmenopausal women with HR + advanced breast cancer (ABC) progressing or recurring after nonsteroidal AI. The primary end point was time to progression (TTP). A fulvestrant loading-dose (LD) regimen was used: 500 mg intramuscularly on day 0, 250 mg on days 14, 28, and 250 mg every 28 days thereafter. Exemestane 25 mg orally was administered once daily. Results A total of 693 women were randomly assigned to fulvestrant (n = 351) or exemestane ( n = 342). Approximately 60% of patients had received at least two prior endocrine therapies. Median TTP was 3.7 months in both groups ( hazard ratio = 0.963; 95% CI, 0.819 to 1.133; P = .6531). The overall response rate ( 7.4% v 6.7%; P = .736) and clinical benefit rate ( 32.2% v 31.5%; P = .853) were similar between fulvestrant and exemestane respectively. Median duration of clinical benefit was 9.3 and 8.3 months, respectively. Both treatments were well tolerated, with no significant differences in the incidence of adverse events or quality of life. Pharmacokinetic data confirm that steady-state was reached within 1 month with the LD schedule of fulvestrant. Conclusion Fulvestrant LD and exemestane are equally active and well-tolerated in a meaningful proportion of postmenopausal women with ABC who have experienced progression or recurrence during treatment with a nonsteroidal AI.

Oral budesonide is as effective as oral prednisolone in active Crohn's disease

Background-The use of corticosteroids in active Crohn's disease often becomes limited by side effects. Budesonide is a potent corticosteroid with low systemic bioavailability due to an extensive first pass liver metabolism. Aims-To compare the efficacy and safety of two dosage regimens of budesonide and prednisolone in patients with active Crohn's disease affecting the ileum and/or the ascending colon. Patients and methods-One hundred and seventy eight patients were randomised to receive budesonide controlled ileal release (CIR) capsules 9 mg once daily or 4.5 mg twice daily, or prednisolone tablets 40 mg once daily. The treatment period was 12 weeks. The primary efficacy variable was clinical remission, defined as a Crohn's Disease Activity Index (CDAI) of 150 or less. Results-After eight weeks of treatment, remission occurred in 60% of patients receiving budesonide once daily or prednisolone and in 42% of those receiving budesonide twice daily (p=0.062). The presence of glucocorticoid associated side effects was similar in all groups; however, moon face was more common in the prednisolone group (p=0.0005). The highest frequency of impaired adrenal function, as measured by a short ACTH test, was found in the prednisolone group (p=0.0023). Conclusions-Budesonide CIR, administered at 9 mg once daily or 4.5 mg twice daily, is comparable to prednisolone in inducing remission in active Crohn's disease. The single dose administration is as promptly effective as prednisolone and represents a simpler and safer therapeutic approach, with a considerable reduction in side effects.

Altered loading patterns and femoral bone mineral density in children with unilateral Legg-Calve-Perthes disease

Maximization of bone accrual during the growing years is thought to be an important factor in minimizing fracture risk in old age. Mechanical loading through physical activity has been recommended as a modality for the conservation of bone mineral in adults; however, few studies have evaluated the impact of different loading regimes in growing children. The purpose of this study was to compare bone mineral density (BMD) in weight-bearing and non-weight-bearing limbs in 17 children with unilateral Legg Calve Perthes Disease (LCPD). Children with this condition have an altered weight-bearing pattern whereby there is increased mechanical loading on the noninvolved normal hip and reduced loading on the involved painful hip. Thus, these children provide a unique opportunity to study the impact of differential mechanical loading on BMD during the growing years while controlling for genetic disposition. BMD at four regions of the proximal femur (trochanter, intertrochanter, femoral neck, total of the regions) was measured using dual energy x-ray absorptiometry (DXA), and the values were compared between the involved and noninvolved sides of the children with LCPD. The BMD of both sides also were compared with normative values based on both chronological and skeletal age data. A significantly higher BMD was found on the noninvolved side over the involved side for all regions (P

Gastroduodenal opportunistic infections and dyspepsia in HIV-infected patients in the era of Highly Active Antiretroviral Therapy

Background and Aim: Dyspeptic symptoms are frequently reported by human immuno-defficiency virus (HIV)-infected patients under highly active antiretroviral therapy. Whether opportunistic infections are a cause of dyspepsia is still unknown. In this study we prospectively compare the prevalence of gastrointestinal opportunistic infections in dyspeptic versus non-dyspeptic HIV-infected patients with advanced immunodeficiency. Patients and Methods: Six hundred and ninety HIV-infected patients under highly active antiretroviral therapy underwent esophagogastroduodenoscopy with mucosal biopsies from the stomach and duodenum. Group 1: 500 patients (161 women, 339 men; mean age 38.8 years; mean CD4 count 154.3 cells/mm(3) with dyspeptic symptoms such as epigastric pain, nausea, vomiting and fullness. Group 2: 190 patients (169 men, 21 women; mean age 40.7 years; mean CD4 count 171.6 cell/mm(3)) with no dyspeptic symptoms. Results: Group 1: Gastrointestinal opportunistic infections were observed in eight (1.6%), and non-opportunistic parasites in two (0.4%), patients. They were: Cytomegalovirus (four patients), Cryptosporidium sp. (two patients), Schistosoma mansoni sp. (one patient), Strongyloides stercoralis (one patient) and Giardia sp. (two patients). In five patients esophagogastroduodenoscopy showed no mucosal lesions. Group 2: Giardia sp. was detected in two patients (1.1%: P = 0.07947). Conclusion: Gastrointestinal opportunistic infections were shown in a small number of HIV-infected patients under highly active antiretroviral therapy with advanced immunodeficiency. Although gastrointestinal opportunistic infections were detected exclusively in the dyspeptic patient group, they could not be related to these symptoms, since the number of infected patients was not statistically significant. To correctly diagnose opportunistic infections, multiple biopsy specimens may be necessary even from normal-appearing mucosa.

CHRONIC ACTIVE EPSTEIN-BARR VIRUS INFECTION MIMICKING HENOCH-SCHONLEIN PURPURA

Introduction: Chronic active Epstein-Barr virus (CAEBV) infection is characterized by chronic or recurrent symptoms for at least 3 months, such as fever, hepatosplenomegaly and lymphadenopathy. The diagnosis is established due to the presence of anti-EBV antibodies or isolation of this infectious agent in affected tissues. Three cases of CAEBV infection mimicking Henoch-Schonlein purpura (HSP) were described. Case 1: Female 3-year old patient with cervical adenomegaly, anemia and fever developed palpable purpura, haematuria and arthritis. CAEBV infection was established by serology test. She received methylprednisolone and acyclovir. She had generalized lymphadenopathy, hepatomegaly, splenomegaly, disseminated intravascular coagulation and deceased. Case 2: Male 12-year old patient with persistent anemia, lymphadenopathy, hepatomegaly and splenomegaly had CAEBV infection diagnosis by serology test. He developed purpura and arthritis and received methylprednisolone. Case 3: Male 13-year old patient had purpura, abdominal pain, haematuria, hepatomegaly, splenomegaly, lymphadenopathy, anemia and elevated liver enzymes. The cervical lymph node biopsy was positive to EBV infection. He received methylprednisolone and acyclovir, developing acute fulminant hepatitis and death. Discussion: CAEBV infection mimicking HSP was rarely observed in our population