Daily Archives: November 8, 2014

Immunotoxic Effects of Fluoride on Hemocytes of Venerupis philippinarum

Ballarin L, Masiero L, Casellato S. Immunotoxic effects of fluoride on the hemocytes of Venerupis philippinarum. Invertebrate Survival Journal. 2014, Vol. 11 Issue 1, p22-29.

The increasing levels of fluoride in the aquatic environments is a matter of concern for freshwater and marine ecosystems. Although data on fluoride toxicity to aquatic organisms are increasing in the scientific literature, few data are available regarding the effects, at cellular level, on freshwater or marine invertebrates. In the present paper, we present data on the effects of in vitro exposure to sodium fluoride (NaF) on the hemocytes of the Manila clam Venerupis philippinarum. Results indicate that NaF reduces cell spreading and phagocytosis in a dose-dependent way, through the alteration of the actin cytoskeleton. In addition, the compound decreases the stability of the lysosomal membranes, as revealed by the Neutral Red assay. In addition, the observed increase in hemocyte mortality and the parallel rise in DNA fragmentation inside their nuclei, as revealed by the TUNEL assay, suggest a NaF-dependent induction of apoptosis, in accordance with the capability of NaF to induce oxidative stress, a known cause of apoptosis, As hemocytes represent the major defence weapon against foreign, potentially pathogenic microbes, the above results indicate a negative effect of NaF on the immune status of V. philippinarum.

Gravity-Driven Membrane Ultrafiltration

Kohler E, Villiger J, Posch T, Derlon N, Shabarova T, Morgenroth E, Pernthaler J, Blom JF. Biodegradation of Microcystins during Gravity-Driven Membrane (GDM) Ultrafiltration.PLoS One. 2014 Nov 4;9(11):e111794. doi: 10.1371/journal.pone.0111794.

Gravity-driven membrane (GDM) ultrafiltration systems require little maintenance: they operate without electricity at ultra-low pressure in dead-end mode and without control of the biofilm formation. These systems are already in use for water purification in some regions of the world where adequate treatment and distribution of drinking water is not readily available. However, many water bodies worldwide exhibit harmful blooms of cyanobacteria that severely lower the water quality due to the production of toxic microcystins (MCs). We studied the performance of a GDM system during an artificial Microcystis aeruginosa bloom in lake water and its simulated collapse (i.e., the massive release of microcystins) over a period of 21 days. Presence of live or destroyed cyanobacterial cells in the feed water decreased the permeate flux in the Microcystis treatments considerably. At the same time, the microbial biofilms on the filter membranes could successfully reduce the amount of microcystins in the filtrate below the critical threshold concentration of 1 µg L-1 MC for human consumption in three out of four replicates after 15 days. We found pronounced differences in the composition of bacterial communities of the biofilms on the filter membranes. Bacterial genera that could be related to microcystin degradation substantially enriched in the biofilms amended with microcystin-containing cyanobacteria. In addition to bacteria previously characterized as microcystin degraders, members of other bacterial clades potentially involved in MC degradation could be identified.

Click here for paper (Open Access).

Fluoride Toxicity and New-Onset Diabetes, Finland

Irmak MK, Ozcelik IS, Kaya A. Fluoride toxicity and new-onset diabetes in Finland: a hypothesis.Journal of Experimental and Integrative Medicine; 2014, Vol. 4 Issue 1, p3-8

The incidence of type 1 diabetes (T1D) has increased substantially in Finland, but the exact trigger for the onset of T1D is still unknown. We know that use of amoxicillin and anti-cariogenic fluoride tablets is a common practice for children in Finland. It seems that beta-cell destruction is initiated by modification of the proinsulin by combined effects of fluoride (F2) and amoxicillin. Amoxicillin especially when used together with clavulanic acid results in an acid environment around the beta-cells that promotes the conversion of F2 to hydrogen fluoride (HF). Unlike F2, HF can diffuse easily into the beta-cell cytosol. Because the cytosol has a neutral pH, virtually all HF reverts to F2 in the cytosol and F2 cannot easily diffuse out of the cell. Exposure to excess F2 promotes proinsulin covalent dimerization and simultaneously hyperexpression of MHC Class I molecules. Proinsulin dimers then migrate to the cell membrane with MHC class I molecules, accumulate at the beta-cell membrane and produces a powerful immunogenic stimulus for the cytotoxic T-cells. Production of cytotoxic cytokines from the infiltrating T-cells initiates the destruction of beta-cells. In Finnish children, this might be helped along by a higher beta-cell activity and by a reactive thymus-dependent immune system induced by higher levels of thyroid hormones and calcitonin respectively. After repeated similar attacks, more and more effector T-cells are raised and more and more beta-cells are destroyed, and clinical diabetes occurs.

Polyacrylonitrile-Based Fibrous Sorbents for Arsenic Removal

At first glance this looks promising. But the laboratory is not the real world. Some additional feasibility work is needed to assess the practicality of this technique.

Chaudhary BK, Farrell J. Preparation and Characterization of Homopolymer Polyacrylonitrile-Based Fibrous Sorbents for Arsenic Removal. Environmental Engineering Science. 2014 Nov 1;31(11):593-601.

This research investigated the modification of homopolymer polyacrylonitrile (PAN) fibers for use as an adsorbent for removing arsenic from drinking water. Fibers were chemically modified and cross-linked using combinations of hydrazine hydrate and sodium hydroxide (NaOH) before being loaded with ferric hydroxide using two different iron loading procedures. Effects of reagent concentrations and reaction times on degree of chemical modification and fiber properties were investigated using Fourier transform infrared spectroscopy and ion-exchange measurements. Arsenate adsorption was a function of both the iron loading and the properties of the underlying fiber. For fibers treated with only a single reagent, both Fe3+ and arsenate adsorption could be understood in terms of ion-exchange properties of the fiber surfaces. However, for fibers treated with both hydrazine and NaOH, the ion-exchange properties of the surface could not explain the Fe3+ and arsenate adsorption behavior. The best arsenate removal performance was obtained using the simplest pretreatment procedure of soaking in 10% NaOH at 95°C for 90 min, followed by precipitation coating of ferric hydroxide. This simple preparation procedure involves only two commonly available and inexpensive reagents and can be carried out without any specialized equipment. This suggests that adsorbents based on inexpensive homopolymer PAN fabric may be produced in developing areas of the world where commercial products may not be available.