Effects of Fe2+/Fe3+ Binding to Human Frataxin and Its D122Y Variant,as Revealed by Site-Directed Spin Labeling (SDSL) EPR Complemented by Fluorescence and Circular Dichroism Spectroscopies

Frataxin is a highly conserved protein whose deficiency results in the neurodegenerative disease Friederich’s ataxia. Frataxin’s actual physiological function has been debated for a long time without reaching a general agreement; however, it is commonly accepted that the protein is involved in the biosynthetic iron-sulphur cluster (ISC) machinery, and several authors have pointed out that it also participates in iron homeostasis. In this work, we use site-directed spin labeling coupled to electron paramagnetic resonance (SDSL EPR) to add new information on the effects of ferric and ferrous iron binding on the properties of human frataxin in vitro. Using SDSL EPR and relating the results to fluorescence experiments commonly performed to study iron binding to FXN, we produced evidence that ferric iron causes reversible aggregation without preferred interfaces in a concentration-dependent fashion, starting at relatively low concentrations (micromolar range), whereas ferrous iron binds without inducing aggregation. Moreover, our experiments show that the ferrous binding does not lead to changes of protein conformation. The data reported in this study reveal that the currently reported binding stoichiometries should be taken with caution. The use of a spin label resistant to reduction, as well as the comparison of the binding effect of Fe²⁺ in wild type and in the pathological D122Y variant of frataxin, allowed us to characterize the Fe²⁺ binding properties of different protein sites and highlight the effect of the D122Y substitution on the surrounding residues. We suggest that both Fe²⁺ and Fe³⁺ might play a relevant role in the context of the proposed FXN physiological functions.     

Silicon-Boron Alloys as New Ultra-High Temperature Phase-Change Materials: Solid/Liquid State Interaction with the h-BN Composite

Silicon-boron alloys have been recently pointed out as novel ultra-high temperature phase change materials for applications in Latent Heat Thermal Energy S     

Water Values: Participatory Water Ecosystem Services Assessment in the Arno River Basin,Italy

Water Resources Management - Water-related Ecosystem Services (WES), namely the multiple benefits that humans can obtain from water or water-related functions of an ecosystem, constitute a useful...     

Isolation, characterization and comparison of antipeptide and antiprotein rabbit antibodies to the pi-isoform of glutathione S-transferase

The main linear epitopes of pi-glutathione transferase (pi-GST, EC 2.5.1.18), an enzyme related to cancer progression in a restricted number of tumours, were identified by testing in ELISA the reactivities of polyclonal anti-pi-GST rabbit sera against a panel of 51 overlapping decapeptides, covering the whole 216-residue sequence of the protein. Several major reactivity peaks were detected, each covering two or three adjacent peptides. The most active fragments were then reconstructed by conventional solid-phase synthesis, linked to Sepharose, and used as affinity ligands for isolating specific anti-pi-GST antibody subsets. A second group of antisera was then prepared in rabbits by using as immunogens some of the above described synthetic fragments, linked to a carrier protein, and antipeptide antibodies purified by affinity chromatography. An ELISA test was then performed, using as antigens a panel of peptides and different isoforms of GST, in order to establish whether antibodies isolated from total anti-pi-GST sera would display higher reactivity and specificity, as compared to traditional antipeptide antibodies. Binding data clearly confirm that the formers might be indeed better reagents for the detection and possibly quantitation of pi-GST.     

Restriction endonuclease mapping and molecular cloning of the human herpesvirus 6 variant B strain Z29 genome

Human herpesvirus 6(HHV-6) variants A and B differ in cell tropism, reactivity with monoclonal antibodies, restriction endonuclease profiles, and epidemiology. Nonetheless, comparative nucleotide and amino acid sequences from several genes indicate that the viruses are very highly conserved genetically, The B variant is the major etiologic agent of exanthem subitum and is frequently isolated from children with febrile illness; no disease has been etiologically associated with HHV-6A. One HHV-6A strain has been cloned and sequenced, but similar information and reagents are not available for HHV-6B. We report here the determination of maps of the restriction endonuclease cleavage sites for BamHI, C1aI, HindIII, KpnI, and Sa1I, and the cloning in plasmids and bacteriophages of fragments representing over 95% of the HHV-6B strain Z29 [HHV-6B(Z29)] genome. Hybridization experiments and orientation of several blocks of nucleotide sequence information onto the genomic map indicate that HHV-6A and HHV-6B genomes are colinear.     

Epidemiology of acute promyelocytic leukemia

BACKGROUND: The estimated incidence of acute promyelocytic leukemia (APL) is approximately 6 cases per 10 million people per year with no apparent differences between sexes. The age of APL cases is younger than that of other acute myeloid leukemias (AML). Spatial and temporal clusters of APL have been reported. These observations suggest a possible selective role for environmental and/or occupational factors in APL development. METHODS: A multicenter case-control study was carried out on risk factors for acute leukemias and preleukemias. In this report data related to APL are selectively analyzed from the larger study to identify specific risk factors. RESULTS: The case-control study on 38 cases of APL showed a strong association with shoemaking (odds ration 6.3, 95% confidence interval 1.3-31.1). A moderate leukemogenic effect from living in houses built with tuff, a polous building material containing gamma-emitting radionuclides and having a high radon concentration, and from using hair dyes was also suggested. CONCLUSIONS: These data, together with the reported spatial and temporal clustering of APL, support the hypothesis of specific environmental and/or occupational risk factors for APL among other AML subtypes and indicate the need for additional ad hoc multicenter studies.     

Occurrence of papillary carcinoma in a hyperfunctioning thyroid nodule: report of a case and diagnostic considerations

HIV-infected patients commonly experience haematological disturbances including anemia, neutropenia or thrombocytopenia. Bone marrow failure may be caused by HIV itself, or by secondary involvement by opportunistic pathogens and malignancy. The need for multiple concomitant suppressive treatments may increase the risk of cytopenias. Strategy to reduce both anemia and neutropenia as well as to improve the haematological tolerance to myelotoxic agents have been developed by using haematological growth factors. So far, erythropoietin and granulocyte(macrophage) colony-stimulating factors have been successfully used in clinical trials including HIV-patients with either zidovudine-associated anemia or severe HIV or drug-induced neutropenia. However, according to the cost of these palliative approaches, there is a need for more reliable data showing that these growth factors could really have a major impact on the patient's compliance to therapy, reduction of hospitalization and infection rate and improvement of the overall survival.     

Treatment of agitation in dementia

Agitation occurs commonly in patients with dementia. Before symptomatic pharmacotherapy is undertaken, it is imperative to perform a sequence of evaluations and interventions to establish whether simpler and safer, nonpharmacologic approaches will be beneficial. When psychotropic medications are used they should be used judiciously, in the lowest effective doses and for the shortest period of time necessary. Ineffective medications should be stopped, and even effective medications should be empirically tapered in most patients to learn whether treatment is still necessary. Antipsychotics probably show the greatest benefit for agitation associated with psychotic features; they have less demonstrated efficacy for agitation not associated with psychotic features. The side effects of typical agents are legion; data are pending regarding atypical agents. The available evidence regarding nonneuroleptic medications ranges from case reports to well-designed, double-blind, placebo-controlled, randomized, parallel group studies. Literature exists describing the use of anticonvulsants, anxiolytics, serotonergic antidepressants, and other agents to manage agitation. Carbamazepine and divalproex sodium (valproate) have demonstrated efficacy in uncontrolled studies, whereas the use of carbamazepine has produced negative results in one small controlled study and positive results in two larger controlled studies. Buspirone has shown benefit in some open trials. Encouraging early findings have been reported for trazodone, including from one controlled trial. Varying results have been obtained using selective serotonin reuptake inhibitors, but with consistently encouraging anecdotes. In the aggregate, the evidence suggests but does not prove that alternatives to traditional antipsychotics exist. Again, none of these agents has yet been approved for this purpose by the FDA. As more studies become available we will have a better idea about which classes of agents are most efficacious. It is likely that there may be a role for "rational" polypharmacy in the management of this distressing complication of dementia. However, no studies that we know of address combination therapy, so the clinician must contemplate this option on a case-by-case basis. Clinical trials data are pending from studies with divalproex sodium, carbamazepine, haloperidol versus trazodone versus placebo, risperidone, olanzapine, quetiapine, donepezil, xanomeline, tacrine, buspirone, and sertraline, at the very least. These data will undoubtedly have a major impact on how we care for our patients and lead to revisions of current practice guidelines.     

Cubature formulae for nearly singular and highly oscillating integrals

The paper deals with the approximation of integrals of the type

$$\begin{aligned} I(f;{\mathbf {t}})=\int _{{\mathrm {D}}} f({\mathbf {x}}) {\mathbf {K}}({\mathbf {x}},{\mathbf {t}}) {\mathbf {w}}({\mathbf {x}}) d{\mathbf {x}},\quad \quad {\mathbf {x}}=(x_1,x_2),\quad {\mathbf {t}}\in \mathrm {T}\subseteq \mathbb {R}^p, \ p\in \{1,2\} \end{aligned}$$

where \({\mathrm {D}}=[-\,1,1]^2\), f is a function defined on \({\mathrm {D}}\) with possible algebraic singularities on \(\partial {\mathrm {D}}\), \({\mathbf {w}}\) is the product of two Jacobi weight functions, and the kernel \({\mathbf {K}}\) can be of different kinds. We propose two cubature rules determining conditions under which the rules are stable and convergent. Along the paper we diffusely treat the numerical approximation for kernels which can be nearly singular and/or highly oscillating, by using a bivariate dilation technique. Some numerical examples which confirm the theoretical estimates are also proposed.

     

Reactive mixing of PET and PET/PP blends with glycidyl methacrylate–modified styrene‐b‐(ethylene‐co‐olefin) block copolymers

Styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene (SEBS) and styrene‐b‐(ethylene‐co‐propylene) (SEP, SEPSEP) block copolymers with different styrene contents and different numbers of blocks in the copolymer chain were functionalized by melt radical grafting with glycidyl methacrylate (GMA) and employed as compatibilizers for PET‐based blends. Binary blends of PET with both functionalized (SEBS‐g‐GMA, SEP‐g‐GMA, SEPSEP‐g‐GMA) and neat (SEBS, SEP, SEPSEP) copolymers (75 : 25 w/w) and ternary blends of PET and PP (75 : 25 w/w) with various amounts (2.5–10 phr) of both modified and unmodified copolymers were prepared in an internal mixer, and their properties were evaluated by SEM, DSC, melt viscosimetry, and tensile and impact tests. The roles of the chemical structure, grafting degree, and concentration of the various copolymers on blend compatibilization was investigated. The blends with the grafted copolymers showed a neat improvement of phase dispersion and interfacial adhesion compared to the blends with nonfunctionalized copolymers. The addition of grafted copolymers resulted in a marked increase in melt viscosity, which was accounted for by the occurrence of chemical reactions between the epoxide groups of GMA and the carboxyl/hydroxyl end groups of PET during melt mixing. Blends with SEPSEP‐g‐GMA and SEBS‐g‐GMA, at concentrations of 5–10 phr, showed a higher compatibilizing effect with enhanced elongation at break and impact resistance. The effectiveness of GMA‐functionalized SEBS was then compared to that of maleic anhydride–grafted SEBS. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2201–2211, 2005