Lessons from case studies of metals: investigating exposure,bioavailability, and risk

Since metals are widely distributed in environmental matrices, humans are exposed to them by either anthropogenic activities or inadvertently by necessity. Selected metals: arsenic, mercury, iron, tin, lead and chromium were chosen on the basis of their economic and public health importance to illustrate the diversity of exposure pathways and differences in factors governing bioavailability. Bioavailability is central to the toxicity of metals and this is discussed from the health risk paradigm standpoint of risk assessment and risk management and the impacts of including or excluding bioavailability in such assessment. The lessons from the case studies of arsenic, mercury, tin and chromium provide a unified concept of methods that can be used in investigating and controlling outbreaks due to metal poisoning in other similar situations.     

Thermal Properties and Flammability Characteristics of a Series of DGEBA-Based Thermosets Loaded with a Novel Bisphenol Containing DOPO and Phenylphosphonate Units

Despite a recent sustained preoccupation for developing biobased epoxies with enhanced applicability, such products have not been widely accepted for industry because of their inferior characteristics compared to classic petroleum-based epoxy thermosets. Therefore, significant effort is being made to improve the flame retardance of the most commonly used epoxies, such as diglycidyl ether-based bisphenol A (DGEBA), bisphenol F (DGEBF), novalac epoxy, and others, while continuously avoiding the use of hazardous halogen-containing flame retardants. Herein, a phosphorus-containing bisphenol, bis(4-(((4-hydroxyphenyl)amino)(6-oxido-6H-dibenzo[c,e][1,2]oxaphosphinin-6-yl)methyl)phenyl) phenylphosphonate (BPH), was synthesized by reacting bis(4-formylphenyl)phenylphosphonate with 4-hydroxybenzaldehyde followed by the addition of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) to the resulting azomethine groups. Environmentally friendly epoxy-based polymer thermosets were prepared by using epoxy resin as polymer matrix and a mixture of BPH and 4,4′-diaminodiphenylsulfone (DDS) as hardeners. A hyperbranched phthalocyanine polymer (HPc) and BaTiO₃ nanoparticles were incorporated into epoxy resin to improve the characteristics of the final products. The structure and morphology of epoxy thermosets were evaluated by infrared spectroscopy and scanning electron microscopy (SEM), while the flammability characteristics were evaluated by microscale combustion calorimetry. Thermal properties were determined by thermogravimetric analysis and differential scanning calorimetry. The surface morphology of the char residues obtained by pyrolysis was studied by SEM analysis.     

Multi‐modality cardiac imaging in advanced chronic kidney disease

Cardiovascular disease (CVD) is the leading cause of death worldwide and is particularly frequent among those with severe renal impairment. Early diagnosis and therapeutic intervention may help alleviate the burden of cardiovascular complication within this population. In the last years, advances have been made toward developing noninvasive imaging techniques that could offer better insight into the cardiac involvement in end‐stage renal disease (ESRD). Conventional transthoracic echocardiography remains the first‐line investigation used to assess cardiac function, but encompassing in our daily practice, the newer approaches such as speckle‐tracking imaging, cardiac computed tomography, or cardiac magnetic resonance can guide us to a more comprehensive understanding of CVD in ESRD. Given that patients with chronic kidney disease may not present with typical CVD symptoms, the amount of information brought by newer imaging techniques is crucial for an accurate diagnosis, risk stratification, and further management. The purpose of this review is to briefly summarize the specific applications of standard cardiac imaging techniques in patients with ESRD and to offer insight into the novel imaging modalities, highlighting the newest research in this field. By doing so, we aim to identify the most important imaging predictors of clinical outcomes in this population.     

Prevention of “learned helplessness” in the rat by hydroxyzine

The effects of hydroxyzine (8, 16, and 32 mg/kg i.p.), administered either 30 min before exposing rats to a series of inescapable shocks (preventive treatment) or during the subsequent acquisition of a shuttle box avoidance response (curative treatment), wereinvestigated. In these conditions untreated rats, previously exposed to inescapable shocks (“stress” ), show a marked increase in escape failures in the shuttle box when compared with nonshocked control animals (“ learned helplessness” ). Control experiments examined the effects of hydroxyzine on memory (passive avoidance test) and on electric shock sensitivity. Diazepam (2 mg/kg i.p.) was used as a reference compound. Hydroxyzine, when administered before “ stress,” clearly decreased at 8 and 32 mg/kg the number of escape failures observed but was without effect when administered after “stress” during the subsequent shuttle box avoidance learning. Similar results were observed with diazepam. Unlike diazepam, hydroxyzine at 32 mg/kg^?1 induced no amnesia in the passive avoidance test, whereas clear amnesia was observed with diazepam. Neither compound altered the rats' sensitivity to shock. These results suggest that hydroxyzine decreases the effects of “ stress” and that these effects cannot be attributed either to impaired memory for the aversive stimulation or to diminished shock sensitivity.     

Experimental determination of blood permittivity and conductivity in simple shear flow

The paper is concerned with the determination of blood permittivity and conductivity in Poiseuille and Couette simple shear flows. The experimental procedure, based on dielectric spectroscopy, evidences the sensitivity of blood electric properties to the applied frequency and local shear rate magnitude. The method evidences the possibility to correlate (for well-defined flow geometry) magnitude of shear rate, and consequently the shear stress level, with spectra permittivity of blood.     

Dynamic Relations Between Sedentary Behavior, Physical Activity, and Body Composition After Bariatric Surgery

Background

Physical activity has been shown to increase following obesity surgery; however, changes in sedentary behavior in this setting are not known. Our aim was to describe changes in both physical activity and sedentary behavior of obese patients after gastric bypass (GBP) and their relationships with changes in body composition.

Methods

Physical activity, time spent watching TV as typical sedentary behavior (self-report), and body composition (DXA) were assessed before and 6 and 12?months after GBP in 86 obese patients (67 women, 24?C66?years old, BMI 41.3?C53.5?kg/m²).

Results

One year after GBP (mean loss of weight ?37.1?kg, fat mass ?25.7?kg, lean body mass ?9.4?kg), leisure-time physical activity (LTPA) significantly increased from 2.0 (SD 3.7) to 3.8 (5.4) h/week and from 7.2 (12.5) to 14.1 (20.1) MET-h/week (MET: metabolic equivalent task), the number of LTPA performed increased from 1.3 (1.3) to 1.8 (1.4), and TV time decreased from 3.0 (1.6) to 2.4 (1.4) h/day (all p?Conclusions Together with increased LTPA, this study shows a decrease in sedentary behavior after GBP, which appears related to favorable changes in body composition. These observations are important to design future intervention studies, including physical activity and sedentary occupations aiming to optimize the care of patients after bariatric surgery.     

Tailoring a Low Young Modulus for a Beta Titanium Alloy by Combining Severe Plastic Deformation with Solution Treatment

The present paper analyzed the microstructural characteristics and the mechanical properties of a Ti–Nb–Zr–Fe–O alloy of β-Ti type obtained by combining severe plastic deformation (SPD), for which the total reduction was of ε_tot = 90%, with two variants of super-transus solution treatment (ST). The objective was to obtain a low Young’s modulus with sufficient high strength in purpose to use the alloy as a biomaterial for orthopedic implants. The microstructure analysis was conducted through X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) investigations. The analyzed mechanical properties reveal promising values for yield strength (YS) and ultimate tensile strength (UTS) of about 770 and 1100 MPa, respectively, with a low value of Young’s modulus of about 48–49 GPa. The conclusion is that satisfactory mechanical properties for this type of alloy can be obtained if considering a proper combination of SPD + ST parameters and a suitable content of β-stabilizing alloying elements, especially the Zr/Nb ratio.     

Synchronous gastric adenocarcinoma and carcinoid

We report the rare case of a 68-year-old man who had two separate and histologically dissimilar gastric tumors: a poorly differentiated adenocarcinoma and a carcinoid. The latter tumor showed argyrophilic granules (Grimelius technique) and positivity for chromogranin A and neuron-specific enolase stains, confirming the neuroendocrine nature of the neoplasia. The literature concerning this subject is reviewed.     

Comparative studies of rat IgG to further delineate the Fc : FcRn interaction site

Recent data have indicated that the MHC class I-related receptor, FcRn, regulates the half-lives of serum IgG in addition to its known role in transferring IgG from mother to young. In the current study, the activity of rat IgG (rIgG) isotypes in FcRn-mediated functions has been analyzed. The serum half-life and maternofetal transfer in mice decreased in the order rIgG2a > rIgG1 > rIgG2c > rIgG2b. This decrease in activity correlates well with reduced binding affinity for soluble mouse FcRn, and site-directed mutagenesis of a recombinant Fc-hinge fragment has been used to investigate the molecular basis for the differences in activities of the rIgG. Analysis of the serum half-lives of the mutated Fc-hinge fragments demonstrated that, in addition to Ile253, His310, His435 and His436 that were identified in earlier studies, amino acids at positions 257, 307 and 309 play a role in building the FcRn interaction site of IgG. The study also excludes the involvement of amino acids in a fourth loop located at the CH2-CH3 domain interface that encompasses residues 386 – 387 in FcRn binding. Sequence differences at positions 257, 307 and 309 between rIgG most likely account for the reduced affinity of rIgG2b and IgG2c relative to rIgG1 and rIgG2a for binding to FcRn.