Effective critical micellar concentration of a zwitterionic detergent: A fluorimetric study on n-dodecyl phosphocholine

We have investigated the effect of ionic strength on the aggregation behavior of n-dodecyl phosphocholine. On the basis of the classical Corrin-Harkins relation, the critical micellar concentration of this detergent decreases with a biphasic trend on lithium chloride addition. It is nearly constant below 150 mM salt, with a mean value of 0.91 mM, whereas it undergoes a dramatic 80-fold decrease in 7 M LiCl. Such a drop in the critical micellar concentration could be explained by the effect of salting out and the implication of phosphocholine head groups on the organization of surrounding water. Knowledge of the effective critical micellar concentration of n-dodecyl phosphocholine could be useful in the purification of membrane proteins in non-denaturing conditions

NMR Structure and CD Titration with Metal Cations of Human Prion α2-Helix-Related Peptides

The 173–195 segment corresponding to the helix 2 of the C-globular prion protein domain could be one of several “spots” of intrinsic conformational flexibility. In fact, it possesses chameleon conformational behaviour and gathers several disease-associated point mutations. We have performed spectroscopic studies on the wild-type fragment 173–195 and on its D178N mutant dissolved in trifluoroethanol to mimic the in vivo system, both in the presence and in the absence of metal cations. NMR data showed that the structure of the D178N mutant is characterized by two short helices separated by a kink, whereas the wild-type peptide is fully helical. Both peptides retained these structural organizations, as monitored by CD, in the presence of metal cations. NMR spectra were however not in favour of the formation of definite ion-peptide complexes. This agrees with previous evidence that other regions of the prion protein are likely the natural target of metal cation binding

AAV-mediated transcription factor EB (TFEB) gene delivery ameliorates muscle pathology and function in the murine model of Pompe Disease

Pompe disease (PD) is a metabolic myopathy due to acid alpha-glucosidase deficiency and characterized by extensive glycogen storage and impaired autophagy. We previously showed that modulation of autophagy and lysosomal exocytosis by overexpression of the transcription factor EB (TFEB) gene was effective in improving muscle pathology in PD mice injected intramuscularly with an AAV-TFEB vector. Here we have evaluated the effects of TFEB systemic delivery on muscle pathology and on functional performance, a primary measure of efficacy in a disorder like PD. We treated 1-month-old PD mice with an AAV2.9-MCK-TFEB vector. An animal cohort was analyzed at 3 months for muscle and heart pathology. A second cohort was followed at different timepoints for functional analysis. In muscles from TFEB-treated mice we observed reduced PAS staining and improved ultrastructure, with reduced number and increased translucency of lysosomes, while total glycogen content remained unchanged. We also observed statistically significant improvements in rotarod performance in treated animals compared to AAV2.9-MCK-eGFP-treated mice at 5 and 8 months. Cardiac echography showed significant reduction in left-ventricular diameters. These results show that TFEB overexpression and modulation of autophagy result in improvements of muscle pathology and of functional performance in the PD murine model, with delayed disease progression

Distribuzione e abbondanza della stigofauna nell\'habitat ipogeo di natura fratturato,nella zona di Nardò (Puglia)

ItLa falda sotterranea nei pressi di Nardò (LE)è stata costantemente monitorata dal CNR-IRSA di Bari a partire dal 1997 e,dal 2001 sono state effettuate le ricerche dei parametri microbiologici di contaminazione fecale.Il Laboratorio Ipogeo Salentino di Biospeleologia “Sandro Ruffo ”ha campionato la fauna sotterranea nelle stesse aree esaminando tre categorie ecologiche:stigosseni,stigo fili e stigobionti. Gli autori hanno voluto veri ficare la sensibilità della stigofauna alle variazioni delle qualità ambientali dell’habitat ipogeo quali cambi di temperatura dell’acqua,di salinità,pH o composizione chimica,tenuto conto che questi organismi partecipano attivamente ai processi degradativi.Dalla ricerca emerge che il misidaceo Spelaeomysis bottazzii non può essere utilizzato come indicatore biologico in quanto è stato ritrovato sia in siti contaminati che in zone non contaminate.EnThe ground water quality at the Nardò (LE)site has been continuously monitored by CNR-IRSA since 1997,and after 2001 also by considering pathogenic indicators due to fecal ground water pollution.In the same area,the Laboratorio Ipogeo Salentino di Biospeleologia “Sandro Ruffo ” sampled the underground fauna and three ecological categories were examined:stygoxenes,stygophiles and stygobi- onts.The authors aimed to check the stygofauna sensitivity to hypogeous habitat changes due to environmental stresses such as water temperature,water salinity, pH or chemical constituents,though they are active organisms which contribute to the biodegradation.Here the possible relationship between sampled aquatic organ- isms and ground water pollution has been focused.The results showed that Spe- laeomysis bottazzii cannot be useful as biological indicator,because the species lives in both contaminated and non-contaminated ground waters

Reactivity of S- or Se- containing model peptides with environmental relevant Hg ions: LC-MS/MS study

Selenium (Se) is an essential element being present in the form of the naturally occurring amino acid selenocysteine (Sec), 25 human proteins involved in different cellular pathways contain Sec. As the most potent intracellular soft Lewis base, selenocysteine (SeCys) is able to bind electron poor soft acids as heavy metals, of awareness for environmental and human toxicology, Hg ions bind Se by means of higher equilibrium constants than sulfur (ca. 106 times), therefore these values compensate the lower cellular abundance (105 times) of selenols compared to thiols[2]. In this communication we present a comparative reactivity study of Hg(I) and Hg(II) compounds with model peptides: vasopressin (AVP) hormone with antidiuretic and vasopressor actions and its Sec containing analogs. These peptides were synthesized either by standard solid phase peptide Fmoc or Boc protocols. The metal ion interaction with these peptides was investigated by RP- LC coupled with electrospray MS/MS detection (LC-MS/MS). We observed mono, bis and bridged peptide metallations as detailed in the Scheme. Taking into consideration the stability of Se-Hg bonds, our results support the hypothesis of a binding preference of Hg to Sec residues in selenoproteins

Structural determinants of unexpected agonist activity in a retro‐peptide analogue of the SDF‐1α N‐terminus

We have synthesised two retro‐peptide analogues of the stromal cell derived growth factor 1 (SDF‐1α) segment known to be critical for CXCR4 receptor binding, corresponding to the sequences HSEFFRCPCRFFESH and HSEFFRGGGRFFESH. We have assayed the ability of these peptides to activate extracellular signal‐regulated kinase 1/2 phosphorylation in cells over expressing the SDF‐1α receptor, finding that the first variant was able to serve as an agonist of CXCR4, whereas the second one was inactive. Finally, by comparing representative solution structures of the two peptides, we have found that the biological response of HSEFFRCPCRFFESH may be ascribed to a β‐β‐type turn motif centred on Phe4–Phe5

Conformational disorder in phosphopeptides: solution studies by CD and NMR techniques

In the last few years intrinsically disordered proteins (IDPs) have received great attention from the scientific community as they participate in several important biological processes and diseases. The intrinsic disorder and flexibility of IDPs grant them a number of advantages with respect to ordered proteins, such as conformational plasticity to bind several targets, a large interaction surface, involvement in high specificity/low affinity interactions, enhanced binding kinetics. It is assumed that post-translational modifications such as phosphorylation can stimulate structural rearrangement in IDPs and facilitate their binding to partners. To better understand at a structural level the multifaceted mechanisms that govern molecular recognition processes involving IDPs, we designed, synthesized by solid phase methods, and structurally characterized unstructured peptides. These molecules contain a putative disordered module, flanked at either the N- or C-terminal ends by a different phosphorylated amino acid (serine or threonine) to mimick the effects of phosphorylation. The absence of an ordered state in the designed peptides was proved experimentally by CD and NMR conformational studies that were carried out under different solution conditions

Treatment of Small Cell Lung Cancer in the Elderly

Abstract Small cell lung cancer (SCLC) accounts for approximately 20% of lung carcinomas. Chemotherapy is the cornerstone of treatment for SCLC. In limited disease, the median survival time is about 12–16 months, with a 4%–5% long-term survival rate; in extensive disease the median survival time is 7–11 months. More than 50% of lung cancer patients are diagnosed when they are over the age of 65, and about 30% are over 70. Elderly patients tolerate chemotherapy poorly compared with their younger counterparts, because of age-related progressive reductions in organ function and comorbidities. The standard therapy for limited disease is combined chemoradiotherapy, followed by prophylactic brain irradiation for patients achieving complete responses. In the elderly, the addition of radiotherapy to chemotherapy must be carefully evaluated, considering the slight survival benefit and potential for substantial toxicity incurred with this treatment. The best approach is to design clinical trials that specifically include geriatric assessment to develop active and well-tolerated chemotherapy regimens for elderly SCLC patients. Survival improvement for SCLC patients requires a better understanding of tumor biology and the subsequent development of novel therapeutic strategies. Several targeted agents have been introduced into clinical trials in SCLC, but a minority of these new agents offers a promise of improved outcomes, and negative results are reported more commonly than positive ones. This review focuses on the main issues in the treatment of elderly SCLC patients