Functional Modulation by Lactate of Myoglobin A MONOMERIC ALLOSTERIC HEMOPROTEIN

The effect of lactate on O2 binding properties of sperm whale and horse heart myoglobins (Mb) has been investigated at moderately acid pH (i.e. pH 6.5, a condition which may be achieved in vivo under a physical effort). Addition of lactate brings about a decrease of O2 affinity (i.e. an increase of P50) in sperm whale and horse heart myoglobins. Accordingly, lactate shows a different affinity for the deoxygenated and oxygenated form, behaving as a heterotropic modulator. The lactate effect on O2 affinity appears to differ for sperm whale and horse heart Mb, δlogP50 being ≈1.0 and ≈0.4, respectively. From the kinetic viewpoint, the variation of O2 affinity for both myoglobins can be attributed mainly to a decrease of the kinetic association rate constant for ligand binding

Microstructural changes induced by ultrashort pulsed lasers in microdrilling of fuel nozzles

Microholes for gasoline direct injection (GDI) nozzles were obtained in martensitic stainless steel AISI 440C with conventional micro-EDM and two laser based processes: water-jet guided s-laser and fs-laser. Since the analyzed drilling methods heavily differ for their thermal input on materials, the three processes were compared from the perspective of the microstructural changes induced in the bulk material after drilling. Moreover, the sharpness of the edges was taken into account as distinctive feature for a comparison among the three processes, being the spray atomization maximized by a cavitation process inside the microhole. A tailored procedure was optimised to prepare the samples for Scanning Electron Microscopy (SEM) and metallographic analyses. The cross sections of micro-EDM drilled samples revealed the presence of a recast (white) layer of 1-2 µm in thickness even using the lowest spark energy in the tested range. Samples drilled by water-jet guided s-laser are affected by the same phenomenon, with an even more pronounced effect. Moreover, they showed the extrusion of the melt material along the hole axis under the action of the water-jet conveying the beam. The extremely fast cooling of this layer also makes the machined surfaces prone to cracking. Conversely, metallographic analysis of cross sections of ultrashort pulsed laser drilled samples, showed no modification of the base metal microstructure in the sub-surface regions, thus testifying that the fs-pulsed laser drilling was an almost pure ablation process and not affected by a remarkable liquid phase as for the other two thermal processes. Periodicity and dimensions of laser induced periodic surface structures (LIPSS) generated by ultrashort pulsed laser were characterized by means of Scanning Electron Microscopy. SEM analysis of the microhole edges revealed burrs for the water-jet guided s-laser while radii of 3-4 µm for micro-EDM and less than 1µm for fs-lasers were measured

pH dependence of structural and functional properties of oxidized cytochrome c" from Methylophilus methylotrophus.

Cytochrome c" from Methylophilus methylotrophus is an unusual monoheme protein that undergoes a major redox-linked change in the heme arrangement: one of the two axial histidines bound to the iron in the oxidized form is detached upon reduction and a proton is taken up. The kinetics of reduction by sodium dithionite and the spectroscopic properties of the oxidized cytochrome c" have been investigated over the pH range between 1.4 and 10.0. The rate of reduction displays proton-linked transitions of pKa congruent with 5.5 and 2.4, and a spectroscopic transition with a pKa congruent with 2.4 is also observed. The protein displays a complete reversibility after exposure to low pH, and both electronic absorption and resonance Raman spectroscopic properties suggest that the transition at lower pH brings about a drastic change in the heme coordination geometry. Circular dichroism spectra indicate that over the same proton-linked transition, the protein undergoes a marked decrease (approximately 60%) of the alpha-helical content toward a random coil arrangement, which is recovered upon increasing the ionic strength. The structural change at low pH is linked to a concerted two-proton transition, suggesting the detachment and protonation of axial histidine(s). Such kinetic and spectroscopic features along with the remarkable capacity of this protein to recover its native structure after exposure to extremely low pH values makes it a promising model for studying folding processes and stability in heme proteins

Maternal Phylogenetic Relationships and Genetic Variation among Rare, Phenotypically Similar Donkey Breeds

The mitochondrial DNA (mtDNA) D-loop of endangered and critically endangered breeds has been studied to identify maternal lineages, characterize genetic inheritance, reconstruct phylogenetic relations among breeds, and develop biodiversity conservation and breeding programs. The aim of the study was to determine the variability remaining and the phylogenetic relationship of Martina Franca (MF, with total population of 160 females and 36 males), Ragusano (RG, 344 females and 30 males), Pantesco (PT, 47 females and 15 males), and Catalonian (CT) donkeys by collecting genetic data from maternal lineages. Genetic material was collected from saliva, and a 350 bp fragment of D-loop mtDNA was amplified and sequenced. Sequences were aligned and evaluated using standard bioinformatics software. A total of 56 haplotypes including 33 polymorphic sites were found in 77 samples (27 MF, 22 RG, 8 PT, 19 CT, 1 crossbred). The breed nucleotide diversity value (π) for all the breeds was 0.128 (MF: 0.162, RG: 0.132, PT: 0.025, CT: 0.038). Principal components analysis grouped most of the haplogroups into two different clusters, I (including all haplotypes from PT and CT, together with haplotypes from MF and RG) and II (including haplotypes from MF and RG only). In conclusion, we found that the primeval haplotypes, haplogroup variability, and a large number of maternal lineages were preserved in MF and RG; thus, these breeds play putative pivotal roles in the phyletic relationships of donkey breeds. Maternal inheritance is indispensable genetic information required to evaluate inheritance, variability, and breeding programs

Coupling of the oxygen-linked interaction energy for inositol hexakisphosphate and bezafibrate binding to human HbA0.

The energetics of signal propagation between different functional domains (i.e. the binding sites for O2, inositol hexakisphospate (IHP), and bezafibrate (BZF)) of human HbA0 was analyzed at different heme ligation states and through the use of a stable, partially heme ligated intermediate. Present data allow three main conclusions to be drawn, and namely: (i) IHP and BZF enhance each others binding as the oxygenation proceeds, the coupling free energy going from close to zero in the deoxy state to -3.4 kJ/mol in the oxygenated form; (ii) the simultaneous presence of IHP and BZF stabilizes the hemoglobin T quaternary structure at very low O2 pressures, but as oxygenation proceeds it does not impair the transition toward the R structure, which indeed occurs also under these conditions; (iii) under room air pressure (i.e. pO2 = 150 torr), IHP and BZF together induce the formation of an asymmetric dioxygenated hemoglobin tetramer, whose features appear reminiscent of those suggested for transition state species (i.e. T- and R-like tertiary conformation(s) within a quaternary R-like structure)

Maternal Phylogenetic Relationships and Genetic Variation among Rare, Phenotypically Similar Donkey Breeds

The mitochondrial DNA (mtDNA) D-loop of endangered and critically endangered breeds has been studied to identify maternal lineages, characterize genetic inheritance, reconstruct phylogenetic relations among breeds, and develop biodiversity conservation and breeding programs. The aim of the study was to determine the variability remaining and the phylogenetic relationship of Martina Franca (MF, with total population of 160 females and 36 males), Ragusano (RG, 344 females and 30 males), Pantesco (PT, 47 females and 15 males), and Catalonian (CT) donkeys by collecting genetic data from maternal lineages. Genetic material was collected from saliva, and a 350 bp fragment of D-loop mtDNA was amplified and sequenced. Sequences were aligned and evaluated using standard bioinformatics software. A total of 56 haplotypes including 33 polymorphic sites were found in 77 samples (27 MF, 22 RG, 8 PT, 19 CT, 1 crossbred). The breed nucleotide diversity value (π) for all the breeds was 0.128 (MF: 0.162, RG: 0.132, PT: 0.025, CT: 0.038). Principal components analysis grouped most of the haplogroups into two different clusters, I (including all haplotypes from PT and CT, together with haplotypes from MF and RG) and II (including haplotypes from MF and RG only). In conclusion, we found that the primeval haplotypes, haplogroup variability, and a large number of maternal lineages were preserved in MF and RG; thus, these breeds play putative pivotal roles in the phyletic relationships of donkey breeds. Maternal inheritance is indispensable genetic information required to evaluate inheritance, variability, and breeding programs

HDV can constrain HBV genetic evolution in hbsag: Implications for the identification of innovative pharmacological targets

Chronic HBV + HDV infection is associated with greater risk of liver fibrosis, earlier hepatic decompensation, and liver cirrhosis hepatocellular carcinoma compared to HBV mono-infection. However, to-date no direct anti-HDV drugs are available in clinical practice. Here, we identified conserved and variable regions in HBsAg and HDAg domains in HBV + HDV infection, a critical finding for the design of innovative therapeutic agents. The extent of amino-acid variability was measured by Shannon-Entropy (Sn) in HBsAg genotype-D sequences from 31 HBV + HDV infected and 62 HBV mono-infected patients (comparable for demographics and virological-parameters), and in 47 HDAg genotype-1 sequences. Positions with Sn = 0 were defined as conserved. The percentage of conserved HBsAg-positions was significantly higher in HBV + HDV infection than HBV mono-infection (p = 0.001). Results were confirmed after stratification for HBeAg-status and patients’ age. A Sn = 0 at specific positions in the C-terminus HBsAg were correlated with higher HDV-RNA, suggesting that conservation of these positions can preserve HDV-fitness. Conversely, HDAg was characterized by a lower percentage of conserved-residues than HBsAg (p < 0.001), indicating higher functional plasticity. Furthermore, specific HDAg-mutations were significantly correlated with higher HDV-RNA, suggesting a role in conferring HDV replicative-advantage. Among HDAg-domains, only the virus-assembly signal exhibited a high genetic conservation (75% of conserved-residues). In conclusion, HDV can constrain HBsAg genetic evolution to preserve its fitness. The identification of conserved regions in HDAg poses the basis for designing innovative targets against HDV-infection

Prevalence of major cardiovascular risk factors among oil and gas and energy company workers

Introduction. Cardiovascular diseases (CVD) remain the biggest cause of disability and premature death throughout the world. Aim. The aim of this study was to describe and determine the prevalence of major cardiovascular risk factors emerged at the first medical examination carried out by a group of an oil and gas contractor company workers in the observation period 2000-2010. Methods. An observational cross-sectional study was conducted on 1073 workers (mean age 41 years, SD = 9.5) presenting overweight BMI (body mass index) values, hypertension and cholesterol problems. Results. In particular, we found that workers > 45 years had significant higher risk to have obesity (OR = 3.8, CI 95% = 2.5-5.7), hypertension (OR = 2.7, CI 95% = 2.1-3.6), high blood fasting glucose (OR = 2.6, CI 95% = 1.2-5.5), high cholesterol (OR = 2.7, CI 95% = 2.0-3.6), high triglycerides (OR = 1.8, CI 95% = 1.4-2.4) compared to younger (< 45 years)

Secondary malignant neoplasms, progression-free survival and overall survival in patients treated for Hodgkin lymphoma: A systematic review and meta-analysis of randomized clinical trials

Treatment intensification to maximize disease control and reduced intensity approaches to minimize the risk of late sequelae have been evaluated in newly diagnosed Hodgkin lymphoma. The influence of these interventions on the risk of secondary malignant neoplasms, progression-free survival and overall survival is reported in the meta-analysis herein, based on individual patient data from 9498 patients treated within 16 randomized controlled trials for newly diagnosed Hodgkin lymphoma between 1984 and 2007. Secondary malignant neoplasms were meta-analyzed using Peto\ue2\u80\u99s method as time-to-event outcomes. For progression-free and overall survival, hazard ratios derived from each trial using Cox regression were combined by inverse-variance weighting. Five study questions (combined-modality treatment vs. chemotherapy alone; more extended vs. involved-field radiotherapy; radiation at higher doses vs. radiation at 20 Gy; more vs. fewer cycles of the same chemotherapy protocol; standard-dose chemotherapy vs. intensified chemotherapy) were investigated. After a median follow-up of 7.4 years, dose-intensified chemotherapy resulted in better progression-free survival rates (P=0.007) as compared with standard-dose chemotherapy, but was associated with an increased risk of therapy-related acute myeloid leukemia/myelodysplastic syndromes (P=0.0028). No progression-free or overall survival differences were observed between combined-modality treatment and chemotherapy alone, but more secondary malignant neoplasms were seen after combined-modality treatment (P=0.010). For the remaining three study questions, outcomes and secondary malignancy rates did not differ significantly between treatment strategies. The results of this meta-analysis help to weigh up efficacy and secondary malignancy risk for the choice of first-line treatment for Hodgkin lymphoma patients. However, final conclusions regarding secondary solid tumors require longer follow-up