BSD extent, an index for metal pollution screening based on the metal content within digestive cell lysosomes of mussels as determined by autometallography

The extent of autometallographical black silver deposits (BSD) has been semiquantified at the light microscope in the gills and digestive gland of either control mussels or Zn-polluted mussels after depuration and on exposure to sublethal concentrations of Cu, Zn, and Cd. The BSD extent in the gills and digestive gland of control mussels was much reduced compared to that in other experimental mussels. The extent of BSD in the gills of depurating mussels was reduced at short depuration times due to decreased levels in the abfrontal cells while in the digestive gland it did not change with the depuration period. The extent of BSD in digestive lysosomes of Cu- and Zn-exposed mussels followed a logarithmic pattern in relation to metal concentration increasing with metal concentrations in the digestive gland. However, a reduced extent of BSD was related to the presence of high metal concentrations under Cd-exposure conditions. This is because the great extent of BSD present in the lumen of the digestive tubules was not taken into account to carry out semiquantification, but, however, the chemical analysis measured the Cd content of these BSD. As such, the extent of BSD in digestive lysosomes followed a logarithmic pattern with total metal concentrations in the digestive gland of Cd-exposed mussels. Therefore, the semiquantitative estimation of BSD in the digestive lysosomes could be considered a reliable index to reflect changes in metal bioavailability in sea water.     

A review of methodologies for assessing drug effectiveness and a new proposal: randomized database studies

The need to evaluate the effects of health technologies in clinical practice is increasingly important. In this article, we review the advantages and limitations of naturalistic randomized clinical trials (RCTs) and database analyses, the two primary methods for evaluating treatment effectiveness. Also, we comment on a newer research strategy, cross-design synthesis, which proposes the complementary use of both experimental RCTs and observational database methodologies to avoid the main weaknesses of each: respectively, the lack of external and internal validity. Finally, we propose a new strategy--randomized database studies--capable of generating results with an acceptable balance between internal and external validity. This strategy consists of the simultaneous use of both experimental and observational tools in the assessment of drugs' effectiveness. Randomization is essential to minimize comparison bias, and one possibility for such studies is that randomization modules could be included in computer-based patient records. Although we identify some of the difficulties in implementing the process, the progressive standardization of clinical practice and the development and widespread adoption of improved computer-based patient records could facilitate the use of randomized database studies as a new method of research.     

Expression of novel genes linked to the androgen-induced, proliferative shutoff in prostate cancer cells

Androgens control cell numbers in the prostate through three separate pathways: (a) inhibition of cell death, (b) induction of cell proliferation (Step-1) and (c) inhibition of cell proliferation (Step-2, proliferative shutoff). The mechanisms underlying these phenomena are incompletely understood. The human prostate carcinoma LNCaP variants express these pathways as follows: LNCaP-FGC express both steps, LNCaP-LNO expresses Step-2, LNCaP-TAC expresses Step-1, and LNCaP-TJA cells express neither step. These cells facilitated the search for mediators of the androgen-induced proliferative shutoff pathway. Androgen exposure for 24 h or longer induced an irreversible proliferative shutoff in LNCaP-FGC cells. The Wang and Brown approach for identifying differentially expressed mRNAs was used to search for mediators of Step-2. Ten unique inserts were identified and from those ten, three genes were further studied. The basal expression of these genes in shutoff-negative variants was not affected by androgen exposure. They were induced by androgens in shutoff-positive LNCaP variants and the androgen receptor-transfected, shutoff-positive, MCF7-AR1 cells. These genes were induced only in the range of androgen concentrations that elicited the shutoff response. Time course analysis showed that their induction precedes the commitment point by 12-18 h. In addition, they were expressed in the normal prostate during proliferative shutoff. These features suggest that the candidate genes have a role in the regulation cascade for proliferative shutoff.     

A comparative study on solvents for separation of tert-amyl ethyl ether and ethanol mixtures. New experimental data for 1-ethyl-3-methyl imidazolium ethyl sulfate ionic liquid

Ionic liquids have potential applications on separation technologies, as solvents for liquid extraction, gas absorbers and others. In this work, the ability of 1-ethyl-3-methyl imidazolium ethyl sulfate, [emim][EtSO₄], to carry out the separation of tert-amyl ethyl ether and ethanol mixtures has been studied. New experimental LLE data for the ternary system are reported. Data correlation was done by means of the NRTL equation with satisfactory results (rmsd=0.429%). Extraction process was studied by means of solute distribution ratio and selectivity of the ionic liquid. Results were compared to other solvents from the literature. Solute distribution ratio for [emim][EtSO₄] was acceptable (higher than 1) and selectivity was better than for other solvents. Then, extraction processes were also simulated using conventional software and obtained results are shown for comparison. Best TAEE recovery was obtained with [emim][EtSO₄] and water.     

Solution properties of poly(thiocarbonates)

Poly(thiocarbonates) with alkyl side chains have been prepared, and the solution properties of these polymers were studied in different solvents. Comparison with other poly(thiocarbonate) analogues and poly(carbonates) shows that the conformational parameter (K_θ) and rigidity factor increase as the volume of the side chain increases. The effect of the side-chain structure on the solution properties is analyzed.     

The effect of a vacancy on the STM image of graphite

Theoretical studies have been done on graphite with a vacancy using the extended Huckel tight-binding (EHTB) method. The results of the singly- and doubly-layered samples show that there is an unexpected distance dependence of the charge density directly over the vacancy. Furthermore, the vacancy acts as a perturbation to distinguish two sublattices which exist in pristine graphite and it creates a charge enhancement in the atoms directly surrounding it.     

X-ray and transmission electron microscopy investigation of strain in a nitrided steel: No evidence of plastic deformation

In order to characterize the nitrided layers of steels, the X-ray diffraction (XRD) technique has been used coupled with transmission electron microscopy (TEM) observations. The TEM observations of the nitrided layers were made using a cross-sectional specimen preparation technique. Using the Warren-Averbach approach to the analysis of the diffraction peak broadening and TEM investigations, the existence of several precipitates of nitrides was brought to the fore, but no evidence for dislocations was found. To improve the calculation of the Fourier coefficient, the diffraction peaks were described in reciprocal lattice by a mixed Cauchy-Gauss curve. In fact, our investigations show that the broadening of the diffraction peaks of nitrided layers is strongly dependent on the size of the coherently diffracting domains. For nitriding, this result confirms that the residual stresses are only attributable to the precipitation of nitrides. In contrast, the microstructural state obtained after mechanical surface treatments, such as shot peening, is very different; the incompatibility of the plastic strains is the origin of the stress field.