Pseudo-static pile load test: expirience on pre-bored and large diameter piles

Pseudostatic load test is usually employed as an alternative to the conventional static load test for piles. Recent developments showed that the well developed Statnamic tests can be substantially simplified by using a hanging weight falling over a cushion system that allows increasing the time length of the generated stress pulse. This work describes the design of the test method and a recently experience related to the application of the pseudostatic load test used to evaluate the bearing capacity of large diameter piles. The performed test showed that using moderate loads from 10 to 20 tons falling from 10 cm to 120 cm and cushions prepared at varied stiffness allowed to reach more than 800 tons of loading and the fully mobilization of the pile ultimate capacity. The main advantages of the proposed pseudostatic tests respect to the conventional Statnamic tests is the possibility to apply load increments by steps, the repeatability of each loading step and the simpler test setup required by the former.Fil: Rinaldi, V. A. Universidad Nacional de Córdoba; Argentina.Fil: Viguera, R. CIM SRL consultants; Argentina.Ingeniería de la Construcció

Sequencing of folding events in Go-like proteins

We have studied folding mechanisms of three small globular proteins: crambin (CRN), chymotrypsin inhibitor 2 (CI2) and the fyn Src Homology 3 domain (SH3) which are modelled by a Go-like Hamiltonian with the Lennard-Jones interactions. It is shown that folding is dominated by a well-defined sequencing of events as determined by establishment of particular contacts. The order of events depends primarily on the geometry of the native state. Variations in temperature, coupling strengths and viscosity affect the sequencing scenarios to a rather small extent. The sequencing is strongly correlated with the distance of the contacting aminoacids along the sequence. Thus $\alpha$-helices get established first. Crambin is found to behave like a single-route folder, whereas in CI2 and SH3 the folding trajectories are more diversified. The folding scenarios for CI2 and SH3 are consistent with experimental studies of their transition states.Comment: REVTeX, 12 pages, 11 EPS figures, J. Chem. Phys (in press

Nuclear localization of the CK2a-subunit correlates with poor prognosis in clear cell renal cell carcinoma

Protein kinase CK2a, one of the two catalytic isoforms of the protein kinase CK2 has been shown to contribute to tumor development, tumor proliferation and suppression of apoptosis in various malignancies. We conducted this study to investigate CK2 expression in different subtypes of Renal Cell Carcinoma (RCC) and in the benign oncocytoma. qRT-PCR, immunohistochemistry and Western blot analyses revealed that CK2a expression was significantly increased at the mRNA and protein levels in clear cell RCC (ccRCC). Also the kinase activity of CK2 was significantly increased in ccRCC compared to normal renal cortex. Nuclear protein expression of CK2a correlated in univariate analysis with poor Progression Free Survival (HR = 8.11, p = 0.016). Functional analyses (cell proliferation assay) revealed an inhibitory effect of Caki-2 cell growth following CK2 inhibition with CX-4945. Our results suggest that CK2a promotes migration and invasion of ccRCC and therefore could serve as a novel prognostic biomarker and molecular therapeutic target in this type of cancer

Conformations of Proteins in Equilibrium

We introduce a simple theoretical approach for an equilibrium study of proteins with known native state structures. We test our approach with results on well-studied globular proteins, Chymotrypsin Inhibitor (2ci2), Barnase and the alpha spectrin SH3 domain and present evidence for a hierarchical onset of order on lowering the temperature with significant organization at the local level even at high temperatures. A further application to the folding process of HIV-1 protease shows that the model can be reliably used to identify key folding sites that are responsible for the development of drug resistance .Comment: 6 pages, 3 eps figure

Sphingosine induces the aggregation of imine-containing peroxidized vesicles

AbstractLipid peroxidation plays a central role in the pathogenesis of many diseases like atherosclerosis and multiple sclerosis. We have analyzed the interaction of sphingosine with peroxidized bilayers in model membranes. Cu2+ induced peroxidation was checked following UV absorbance at 245nm, and also using the novel Avanti snoopers®. Mass spectrometry confirms the oxidation of phospholipid unsaturated chains. Our results show that sphingosine causes aggregation of Cu2+-peroxidized vesicles. We observed that aggregation is facilitated by the presence of negatively-charged phospholipids in the membrane, and inhibited by anti-oxidants e.g. BHT. Interestingly, long-chain alkylamines (C18, C16) but not their short-chain analogues (C10, C6, C1) can substitute sphingosine as promoters of vesicle aggregation. Furthermore, sphinganine but not sphingosine-1-phosphate can mimic this effect. Formation of imines in the membrane upon peroxidation was detected by 1H-NMR and it appeared to be necessary for the aggregation effect. 31P-NMR spectroscopy reveals that sphingosine facilitates formation of non-lamellar phase in parallel with vesicle aggregation. The data might suggest a role for sphingosine in the pathogenesis of atherosclerosis

SK channels contribution to ventricular electrophysiology in heart failure patients

Heart failure (HF) is characterized by deterioration of the electrical and contractile function of the heart due to structural and functional remodelling, leading to development of arrhythmias and increased sudden cardiac death risk. SK channels are a type of calcium-activated potassium channels that do not play a relevant role in normal ventricular electrophysiology. However, it has been hypothesized that these channels become more relevant in pathologies such as HF. Nontheless, their role in human ventricular electrophysiology is not fully characterized

Inhibition of intermediate-conductance calcium-activated K channel (KCa3.1) and fibroblast mitogenesis by a-linolenic acid and alterations of channel expression in the lysosomal storage disorders, fabry disease, and niemann pick C

The calcium/calmodulin-gated KCa3.1 channel regulates normal and abnormal mitogenesis by controlling K+-efflux, cell volume, and membrane hyperpolarization-driven calcium-entry. Recent studies suggest modulation of KCa3.1 by omega-3 fatty acids as negative modulators and impaired KCa3.1 functions in the inherited lysosomal storage disorder (LSD), Fabry disease (FD). In the first part of present study, we characterize KCa3.1 in murine and human fibroblasts and test the impact of omega-3 fatty acids on fibroblast proliferation. In the second, we study whether KCa3.1 is altered in the LSDs, FD, and Niemann-Pick disease type C (NPC). Our patch-clamp and mRNA-expression studies on murine and human fibroblasts show functional expression of KCa3.1. KCa currents display the typical pharmacological fingerprint of KCa3.1: Ca2+-activation, potentiation by the positive-gating modulators, SKA-31 and SKA-121, and inhibition by TRAM-34, Senicapoc (ICA-17043), and the negative-gating modulator, 13b. Considering modulation by omega-3 fatty acids we found that a-linolenic acid (a-LA) and docosahexanenoic acid (DHA) inhibit KCa3.1 currents and strongly reduce fibroblast growth. The a-LA-rich linseed oil and ¿-LA-rich borage oil at 0.5% produce channel inhibition while a-LA/¿-LA-low oils has no anti-proliferative effect. Concerning KCa3.1 in LSD, mRNA expression studies, and patch-clamp on primary fibroblasts from FD and NPC patients reveal lower KCa3.1-gene expression and membrane expression than in control fibroblasts. In conclusion, the omega-3 fatty acid, a-LA, and a-LA/¿-LA-rich plant oils, inhibit fibroblast KCa3.1 channels and mitogenesis. Reduced fibroblast KCa3.1 functions are a feature and possible biomarker of cell dysfunction in FD and NPC and supports the concept that biased lipid metabolism is capable of negatively modulating KCa3.1 expression

Conditional KCa3.1-transgene induction in murine skin produces pruritic eczematous dermatitis with severe epidermal hyperplasia and hyperkeratosis

Ion channels have recently attracted attention as potential mediators of skin disease. Here, we explored the consequences of genetically encoded induction of the cell volume-regulating Ca2+-activated KCa3.1 channel (Kcnn4) for murine epidermal homeostasis. Doxycycline-treated mice harboring the KCa3.1+-transgene under the control of the reverse tetracycline-sensitive transactivator (rtTA) showed 800-fold channel overexpression above basal levels in the skin and solid KCa3.1-currents in keratinocytes. This overexpression resulted in epidermal spongiosis, progressive epidermal hyperplasia and hyperkeratosis, itch and ulcers. The condition was accompanied by production of the pro-proliferative and pro-inflammatory cytokines, IL-ß1 (60-fold), IL-6 (33-fold), and TNFa (26-fold) in the skin. Treatment of mice with the KCa3.1-selective blocker, Senicapoc, significantly suppressed spongiosis and hyperplasia, as well as induction of IL-ß1 (-88%) and IL-6 (-90%). In conclusion, KCa3.1-induction in the epidermis caused expression of pro-proliferative cytokines leading to spongiosis, hyperplasia and hyperkeratosis. This skin condition resembles pathological features of eczematous dermatitis and identifies KCa3.1 as a regulator of epidermal homeostasis and spongiosis, and as a potential therapeutic target