Obestatin was identified as a gut peptide encoded by the ghrelin gene that interacts with the G protein-coupled receptor, GPR39. In this work, a sequential analysis of its transmembrane signalling ...pathway has been undertaken to characterize the intracellular mechanisms responsible for Akt activation. The results show that Akt activation requires the phosphorylation of T308 in the A-loop by the phosphoinositide-dependent kinase 1 (PDK1) and S473 within the HM by the mammalian target of rapamycin (mTOR) kinase complex 2 (mTORC2: Rictor, mLST8, mSin1, mTOR kinase) with participation neither of G(i)(/o)-protein nor Gbetagamma dimers. Obestatin induces the association of GPR39/beta-arrestin 1/Src signalling complex resulting in the transactivation of the epidermal growth factor receptor (EGFR) and downstream Akt signalling. Upon administration of obestatin, phosphorylation of mTOR (S2448) and p70S6K1 (T389) rise with a time course that parallels that of Akt activation. Based on the experimental data obtained, a signalling pathway involving a beta-arrestin 1 scaffolding complex and EGFR to activate Akt signalling is proposed.
Abstract
Highly nonlinear optical processes require high intensities, typically achieved with ultrashort laser pulses, and hence, they were first observed with the advent of picosecond laser ...technology. An alternative approach for reaching the required field intensities is offered by localized optical resonances in tailored plasmonic nanostructures, enabling the enhancement of a multitude of nonlinear phenomena. However, so far, plasmon-enhanced high-order nonlinear effects have been restricted to experiments involving short-pulsed and ultrafast laser sources. Here, we demonstrate localized three-photon photoemission from chemically synthesized plasmonic gold nanostars under continuous-wave illumination at sub-MWcm
−2
incident intensities. Intensity- and polarization-dependent measurements confirm the nonlinearity of the photoemission process and agree with quantum mechanical calculations of the electron yield from nanostar tips with features smaller than 5 nm, which facilitate local intensity enhancement factors exceeding 1000. Our results open up new avenues for the design of accessible nanoscale coherent electron sources, with potential applications in microscopy, spectroscopy, sensing, and signal processing.
Actinoporins constitute a unique class of pore-forming toxins found in sea anemones that are able to bind and oligomerize in membranes, leading to cell swelling, impairment of ionic gradients and, ...eventually, to cell death. In this review we summarize the knowledge generated from the combination of biochemical and biophysical approaches to the study of sticholysins I and II (Sts, StI/II), two actinoporins largely characterized by the Center of Protein Studies at the University of Havana during the last 20 years. These approaches include strategies for understanding the toxin structure–function relationship, the protein–membrane association process leading to pore formation and the interaction of toxin with cells. The rational combination of experimental and theoretical tools have allowed unraveling, at least partially, of the complex mechanisms involved in toxin–membrane interaction and of the molecular pathways triggered upon this interaction. The study of actinoporins is important not only to gain an understanding of their biological roles in anemone venom but also to investigate basic molecular mechanisms of protein insertion into membranes, protein–lipid interactions and the modulation of protein conformation by lipid binding. A deeper knowledge of the basic molecular mechanisms involved in Sts–cell interaction, as described in this review, will support the current investigations conducted by our group which focus on the design of immunotoxins against tumor cells and antigen-releasing systems to cell cytosol as Sts-based vaccine platforms.
The quest for therapeutic applications of obestatin involves, as a first step, the determination of its 3D solution structure and the relationship between this structure and the biological activity ...of obestatin. On this basis, we have employed a combination of circular dichroism (CD), nuclear magnetic resonance (NMR) spectroscopy, and modeling techniques to determine the solution structure of human obestatin (1). Other analogues, including human non-amidated obestatin (2) and the fragment peptides (6-23)-obestatin (3), (11-23)-obestatin (4), and (16-23)-obestatin (5) have also been scrutinized. These studies have been performed in a micellar environment to mimic the cell membrane (sodium dodecyl sulfate, SDS). Furthermore, structural-activity relationship studies have been performed by assessing the in vitro proliferative capabilities of these peptides in the human retinal pigmented epithelial cell line ARPE-19 (ERK1/2 and Akt phosphorylation, Ki67 expression, and cellular proliferation). Our findings emphasize the importance of both the primary structure (composition and size) and particular segments of the obestatin molecule that posses significant α-helical characteristics. Additionally, details of a species-specific role for obestatin have also been hypothesized by comparing human and mouse obestatins (1 and 6, respectively) at both the structural and bioactivity levels.
Wreckfish (Polyprion americanus) is considered to be a good candidate for European aquaculture. The main biometric parameters were recorded from 86 wild-caught fish (2.6-18 kg of total weight) for 14 ...months and the gonadosomatic index (GSI), hepatosomatic index (HIS) and viscerosomatic index (VSI) were obtained. Biochemical analyses of muscle, liver and gonads from wild wreckfish showed that wreckfish has a high level of protein in muscle, 84% of dry weight (DW), and low level of lipids (7% DW). Capture season, sex, size or weight of the fish did not have a strong effect on the variability observed in the levels of proteins, lipids and fatty acids of the different tissues. Reared wreckfish have more lipids in mature gonads than wild fish, which may be due to a more lipid-rich diet. However, some polyunsaturated fatty acids (PUFA) such as arachidonic acid (ARA) and docosahexaenoic acid (DHA) reached higher values in wild female gonads than in reared gonads, which could indicate the wreckfish has high requirements in these fatty acids. This study obtained valuable data on the biology and biochemical composition of wreckfish to estimate its nutritional requirements, which could be useful for the future of this species in aquaculture.
•TLR4/MyD88 pathway is relevant for Sts-induced dendritic cells maturation.•The 3D-structure of Sts is important for inducing dendritic cells maturation.•Free Sts mediate Ag cross-presentation in ...dendritic cells with CD8+ T cell priming.•TLR4 is involved in the CD8+ T cell response induced by StII-carrying liposomes.
Sticholysins (Sts) I and II (StI and StII) are pore-forming proteins (PFPs), purified from the Caribbean Sea anemone Stichodactyla helianthus. StII encapsulated into liposomes induces a robust antigen-specific cytotoxic CD8+ T lymphocytes (CTL) response and in its free form the maturation of bone marrow-derived dendritic cells (BM-DCs). It is probable that the latter is partially supporting in part the immunomodulatory effect on the CTL response induced by StII-containing liposomes. In the present work, we demonstrate that the StII’s ability of inducing maturation of BM-DCs is also shared by StI, an isoform of StII. Using heat-denatured Sts we observed a significant reduction in the up-regulation of maturation markers indicating that both PFP’s ability to promote maturation of BM-DCs is dependent on their conformational characteristics. StII-mediated DC maturation was abrogated in BM-DCs from toll-like receptor (TLR) 4 and myeloid differentiation primary response gene 88 (MyD88)-knockout mice but not in cells from TLR2-knockout mice. Furthermore, the antigen-specific CTL response induced by StII-containing liposomes was reduced in TLR4-knockout mice. These results indicate that StII, and probably by extension StI, has the ability to induce maturation of DCs through a TLR4/MyD88-dependent pathway, and that this activation contributes to the CTL response generated by StII-containing liposomes.
The synthesis and pharmacological activity of a new series of bicyclic diazepinones with dual activity toward the α2δ-1 subunit of voltage-gated calcium channels (Cavα2δ-1) and the norepinephrine ...transporter (NET) are reported. Exploration of the positions amenable for substitution on a nonaminoacidic Cavα2δ-1 scaffold allowed the identification of favorable positions for the attachment of NET pharmacophores. Among the patterns explored, attachment of the 2-ethylamino-9-methyl-6-phenyl-6,7,8,9-tetrahydro-5H-pyrimido4,5-e1,4diazepin-5-one framework to the meta-position of the phenyl ring of the 3-methylamino-1-phenylpropoxy and 3-methylamino-1-thiophenylpropoxy moieties provided dual compounds with excellent NET functionality. Alternative bicyclic frameworks were also explored, and some lead molecules were identified, which showed a balanced dual profile and exhibited good ADMET properties.
Male, 36 FINAL DIAGNOSIS: Levamisole-induced vasculopathy Symptoms: Purpuric skin lesions Medication: Levamisole Clinical Procedure: - Specialty: Internal Medicine.
Unusual clinical course.
...Levamisole has been detected in seized cocaine samples and a levamisole-induced vasculopathy (LIV) has been described, mainly focused on skin.
A 36-year-old Caucasian man with history of antibodies to hepatitis C infection (negative hepatitis C virus RNA and negative HIV serology), smoking, and intravenous use of cocaine and brown heroin, presented to the hospital with purpuric skin lesions on extremities and earlobes. One month before the current presentation, a skin punch biopsy of one of these lesions was performed, showing histopathologic findings suggestive of mixed cryoglobulinemia. Laboratory testing revealed leukopenia, renal failure, and nephrotic syndrome. Antimyeloperoxidase antineutrophil cytoplasmic antibodies (MPO-ANCA) were positive. The previous skin punch biopsy was revised and demonstrated pathologic findings consistent with leukocytoclastic vasculitis. An analysis of a cocaine sample for personal use, provided by the patient, was performed using mass spectrometry-gas chromatography and levamisole was detected. Three boluses of intravenous methylprednisolone were administered, followed by oral prednisone 1 mg/Kg per day. Skin lesions and renal function improved.
To our knowledge, this is the first report of nephrotic syndrome induced by levamisole-adulterated cocaine, proven by cocaine sample toxicology. Lack of renal biopsy is a limitation of this report.
Introduction: cerebrovascular disease is one of the main causes of long-term disability, with a high incidence of transient brain ischemic attacks. Objective: to determine the behavior of ...clinical-epidemiological variables in patients admitted with the diagnosis of transient brain ischemic attacks at Roberto Rodriguez Fernandez General Provincial Teaching Hospital from Moron municipality, Ciego de Avila province. Method: an observational, descriptive, cross-sectional study was conducted during the period from September 2019 to January 2020. The target group consisted of 39 patients, working with all of them. Descriptive statistics was used, by distribution of data according to absolute and relative percentage frequency. Results: there was a predominance of patients aged 60 years and over (82,1 %) and male sex (66,7 %); high blood pressure (74,3 %) was the main risk factor for the development of a transient brain ischemia attack; 46,2 % of the patients attended the hospital 24 hours after the onset of symptoms. Of the patients, 46,2 % attended the hospital within 24 hours of the onset of symptoms. Conclusions: patients older than 60 years, as well as male patients, hypertensive and/or smokers were prone to the development of transient brain ischemic attack. Attendance at health services after 24 hours was common.
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