Biodynamics of mercury in mussel tissues as a function of exposure pathway: natural vs microplastic routes

In the marine environment, metals can be present dissolved or adsorbed to suspended particles. In the last decades a new type of particle has been introduced, microplastics (MPs). The exposure route of pollutants influences their accumulation and distribution into tissues. A pulse-chase experiment was conducted in which mussels were exposed to Hg: adsorbed onto MPs and microalgae (MA) and dissolved (WB). Mussels accumulated the same amount of Hg independently of particle, due to the Hg loading in both particles and their acceptability were similar. The highest Hg accumulation occurred in gill when the Hg exposure was through water and in digestive gland when Hg was adsorbed to particles. More than 70% of the Hg uptake through MPs was quickly eliminated due to: i) part of the cleared MPs might not really be ingested but adhered to body surfaces of mussels, ii) MPs ingested were eliminated through faeces as they are non-nutritive particles which may be rejected in stomach preventing their entry into digestive gland and iii) high affinity of Hg on surface of MPs which meant that Hg was mainly eliminated jointly to MPs. The organic nature of MA facilitates the entry of Hg into digestive gland where MA are intracellularly digested releasing the Hg adsorbed onto their surfaces. In this case, Hg may reach deeper levels by translocation of the Hg incorporated into gland towards foot and remaining tissues, a process that might occur through haemolymph. All of the Hg accumulated in WB during the exposure was internally absorbed into tissues, and later translocated from gill to gland. Although Hg elimination rate in MPs mussels was greater than in the other exposure pathways, an important amount of Hg was maintained through the depuration period, thus we cannot and should not neglect the risk of MPs as vectors for mercury.

[Pharmaceutical intervention in duration of antimicrobial treatment at hospital ambit]

OBJECTIVE

To estimate the acceptance of the pharmaceutical intervention in controlling duration of antimicrobial therapy and to evaluate their impact on optimizing the treatment.

METHODS

Prospective observational study for two years in a General University Hospital. For the patients record, we followed non critical adult patients with antibiotic treatment. When the duration of antimicrobial treatment not complied with established criteria for each antibiotic and pathology, there was a communication with the physician, at which is recommended to assess the need for continue treatment. The acceptance of pharmaceutical intervention was collected and afterwards we analyzed the impact of this work by antimicrobial consumption and incidence of Clostridium difficile.

RESULTS

. In 122 patients the pharmacist made a pharmaceutical intervention due to prolonged antibiotic treatment. The most prevalent antibiotics were β-lactams, specifically meropenem. The intravenous administration was more frequent. In 77 cases it was decided to recommend the suspension of treatment, we conducted an orally prospective intervention at 70.15 % and the rest of interventions were written. Acceptance was 65.95 % and 65.00%, respectively. During the study period, the DDD of the antimicrobials decreased by 8.89% and expenditure on antimicrobials one 40.12%. The incidence of C. difficile was stable.

CONCLUSIONS

. In a hospital, a pharmaceutical counselling program on the duration of antimicrobial therapy is well accepted by the prescriber physician, but it must be improved. The route of information does not affect the degree of acceptance. These actions could involve a reduction of antimicrobial consumption.

Vitamin E deficiency induces liver nuclear factor-κB DNA-binding activity and changes in related genes

The biological functions of vitamin E have been classically attributed to its property as a potent inhibitor of lipid peroxidation in cellular membranes. However, in 1991, Azzi's group first described that alpha-tocopherol inhibits smooth muscle cell proliferation in a protein kinase C (PKC)-dependent way, demonstrating a non-antioxidant cell signalling function for vitamin E. More recently, the capacity of alpha-tocopherol to modulate gene expression with the implication of different transcription factors, beyond its antioxidant properties, has also been established. This study was to determine the effect of vitamin E-deficiency on liver nuclear factor-kappa B (NF-kappaB) DNA-binding activity and the response of target antioxidant-defense genes and cell cycle modulators. Rats were fed either control diet or vitamin-E free diet until 60 or 90 days after birth. Vitamin E-deficiency enhanced liver DNA-binding activity of NF-kappaB [electrophoretic mobility-shift assay, (EMSA)] and up-regulated transcription of gamma-glutamylcysteine synthetase (gamma-GCSM; gamma-GCSC), cyclin D1 and cyclin E. We also showed down-regulation of p21(Waf1/Cip1) transcription. Western-blot analysis demonstrated that gamma-glutamylcysteine synthetase catalytic subunit (gamma-GCSC) and cyclin D1 showed a similar pattern to that found in the RT-PCR analysis. Moreover, chromatin immunoprecipitation (ChIP) assay demonstrated that NF-kappaB directly regulates transcription of gamma-GCS (both subunits) and cyclin D1 through the binding of NF-kappaB to the corresponding gene promoters, which was enhanced in vitamin E-deficiency. These findings show that vitamin E-deficiency induces significant molecular regulatory properties in liver cells with an altered expression of both antioxidant-defense genes and genes that control the cell cycle and demonstrate that liver NF-kappaB activation is involved in this response. Our results emphasize the importance of maintaining an adequate vitamin E consumption not only to prevent liver oxidative damage but also in modulating signal transduction.

Id2 leaves the chromatin of the E2F4-p130-controlled c-myc promoter during hepatocyte priming for liver regeneration

The Id (inhibitor of DNA binding or inhibitor of differentiation) helix-loop-helix proteins are involved in the regulation of cell growth, differentiation and cancer. The fact that the molecular mechanisms of liver regeneration are not completely understood prompted us to study the fate of Id2 in proliferating liver. Id2 increases in liver regeneration after partial hepatectomy, following the early induction of its gene. Co-immunoprecipitation shows that Id2 forms a complex with E2F4, p130 and mSin3A in quiescent liver and all these components are present at the c-myc promoter as shown using ChIP (chromatin immunoprecipitation). Activation of c-myc during hepatocyte priming (G0-G1 transition) correlates with the dissociation of Id2 and HDAC (histone deacetylase), albeit p130 remains bound at least until 6 h. Moreover, as the G0-G1 transition progresses, Id2 and HDAC again bind the c-myc promoter concomitantly with the repression of this gene. The time course of c-myc binding to the Id2 promoter, as determined by ChIP assays is compatible with a role of the oncoprotein as a transcriptional inducer of Id2 in liver regeneration. Immunohistochemical analysis shows that Id2 also increases in proliferating hepatocytes after bile duct ligation. In this case, the pattern of Id2 presence in the c-myc promoter parallels that found in regenerating liver. Our results may suggest a control role for Id2 in hepatocyte priming, through a p130 dissociation-independent regulation of c-myc.

In vivo studies of altered expression patterns of p53 and proliferative control genes in chronic vitamin A deficiency and hypervitaminosis

Several clinical trials have revealed that individuals who were given beta-carotene and vitamin A did not have a reduced risk of cancer compared to those given placebo; rather, vitamin A could actually have caused an adverse effect in the lungs of smokers [Omenn, G.S., Goodman, G.E., Thornquist, M.D., Balmes, J., Cullen, M.R., Glass, A., Keogh, J.P., Meyskens, F.L., Valanis, B., Williams, J.H., Barnhart, S. & Hammar, S. N. Engl. J. Med (1996) 334, 1150-1155; Hennekens, C.H., Buring, J.E., Manson, J.E., Stampfer, M., Rosner, B., Cook, N.R., Belanger, C., LaMotte, F., Gaziano, J.M., Ridker, P.M., Willet, W. & Peto, R. (1996) N. Engl. J. Med. 334, 1145-1149]. Using differential display techniques, an initial survey using rats showed that liver RNA expression of c-H-Ras was decreased and p53 increased in rats with chronic vitamin A deficiency. These findings prompted us to evaluate the expression of c-Jun, p53 and p21WAF1/CIF1 (by RT-PCR) in liver and lung of rats. This study showed that c-Jun levels were lower and that p53 and p21WAF1/CIF1 levels were higher in chronic vitamin A deficiency. Vitamin A supplementation increased expression of c-Jun, while decreasing the expression of p53 and p21WAF1/CIF1. Western-blot analysis demonstrated that c-Jun and p53 showed a similar pattern to that found in the RT-PCR analyses. Binding of retinoic acid receptors (RAR) to the c-Jun promoter was decreased in chronic vitamin A deficiency when compared to control hepatocytes, but contrasting results were found with acute vitamin A supplementated cells. DNA fragmentation and cytochrome c release from mitochondria were analyzed and no changes were found. In lung, an increase in the expression of c-Jun produced a significant increase in cyclin D1 expression. These results may explain, at least in part, the conflicting results found in patients supplemented with vitamin A and illustrate that the changes are not restricted to lung. Furthermore, these results suggest that pharmacological vitamin A supplementation may increase the risk of adverse effects including the risk of oncogenesis.

On the rate of tubal pregnancy contralateral to the corpus luteum

Ectopic implantation of the embryo in the tube opposite to the ovary containing the corpus luteum constitutes evidence of peritoneal or uterine transmigration of the egg. The frequency of this phenomenon was reinvestigated utilizing histopathologic confirmation of the side of the corpus luteum. A tubal pregnancy contralateral to the ovulating ovary was found in 28% of 67 cases, indicating that either the oocyte, the zygote or the embryo had entered the tube in which implantation took place from a medial site such as the peritoneal or the uterine cavity rather than directly from the ovulating ovary. Assuming that once in the medial site there is equal chance of entering either tube, it follows that in 56% of tubal pregnancies the egg has entered the tube from a midline location. Attempts to recover the oocyte from the tubes in normal women were successful in fewer than 5% of cases contralateral to the corpus luteum. It is concluded that tubal pregnancy is associated with a significant increase in the occurrence of transmigration of the egg.