Subchronic malathion treatment effects on rat intestinal functions

Effects of exposure to malathion on blood glucose concentration: a meta-analysis

Exposure to malathion (an organophosphate pesticide widely used around the world) has been associated with alterations in blood glucose concentration in animal models. However, the results are inconsistent. The aim of this meta-analysis was to evaluate whether malathion exposure can disturb the concentrations of blood glucose in exposed rats. We performed a literature search of online databases including PubMed, EBSCO, and Google Scholar and reviewed original articles that analyzed the relation between malathion exposure and glucose levels in animal models. The selection of articles was based on inclusion and exclusion criteria. The database search identified thirty-five possible articles, but only eight fulfilled our inclusion criteria, and these studies were included in the meta-analysis. The effect of malathion on blood glucose concentration showed a non-monotonic dose-response curve. In addition, pooled analysis showed that blood glucose concentrations were 3.3-fold higher in exposed rats than in the control group (95% CI, 2-5; Z = 3.9; p < 0.0001) in a random-effect model. This result suggested that alteration of glucose homeostasis is a possible mechanism of toxicity associated with exposure to malathion.

Inclusion effect of alpha-cyclodextrin on chemical degradation of malathion water

Chemical degradation of malathion in water is one of the important environmental processes of malathion, and plays a critical role in detoxification of malathion. Alpha-cyclodextrin (alpha-CD), one of the cyclic oligosaccharides different from beta-cyclodextrin (beta-CD) in glucose units, solubility, and size of cavity, is capable of producing an environmental effect different from those of the latter CD and its derivatives. This work evaluated the effect of alpha-CD on chemical degradation of malathion in water in an attempt to further study the effects of different CDs on hydrolysis of malathion and assess the potential applications of alpha-CD in remediation of malathion contamination. The results showed that alpha-CD had a remarkable facilitative effect on the hydrolysis of malathion in both buffer solutions and natural surface waters. The facilitative effects of alpha-CD were an obverse function of pH value and inverse function of temperature. The rate constant of malathion hydrolysis increased with increasing the concentration of alpha-CD in both types of waters. Urea, a compound widely used in agriculture, decreased the facilitative effect of alpha-CD at 25 degrees C and pH 9.0. The formation of inclusion complexes between alpha-CD and malathion was evidenced by nuclear magnetic resonance studies.

High-dose exposure to systemic phosmet insecticide modifies the phosphatidylinositol anchor on the prion protein: the origins of new variant transmissible spongiform encephalopathies?

Compulsory exposure of the UK bovine to exclusively high biannual doses of a 'systemic' pour-on formulation of an organo-phthalimido-phosphorus warblecide, phosmet, during the 1980s (combined with exposure to the lipid-bound residues of 'bioconcentrated' phosmet recycled back via the intensive feeding of meat and bone meal), initiated the 'new strain' modification of the CNS prion protein (PrP) causing the UK's bovine spongiform encephalopathy (BSE) epidemic. A lipophilic solution of phosmet was poured along the bovine's spinal column, whence it penetrated and concentrated in phospholipids of the CNS membranes, covalently modifying endogenous phosphorylation sites on phosphatidylinositols (PIs) etc., forming a 'toxic membrane bank' of abnormally modified lipids that 'infect' any membrane proteins (such as PrP) that are programmed to conjugate onto them for anchorage to the membrane. Thus, phosmet invokes a primary covalent modification on PrP's PI anchor which, in turn, invokes an overall diverse disturbance upon CNS phosphoinositide second messenger feed back cycle, calcium homeostasis and essential free radicals; thus initiating a self-perpetuating cascade of abnormally phosphorylated PI-PrP that invokes a secondary electrostatic and allosteric disturbance on the main body of PrP impairing tertiary folding. Chaperone stress proteins conjugate onto misfolded PrP blocking its sites of proteolytic cleavage. Fresh epidemiological evidence is presented and experimental evidence referenced that adds support to a multifactorial hypothesis which proposes that BSE is a hitherto unrecognized and previously unmanifested class of subtle chronic phosmet-induced delayed neuro-excitotoxicity in the susceptible bovine.

Proabsorptive properties of forskolin: disposition of glycine, leucine and lysine in rat jejunum

The effects of forskolin on mucosal cyclic AMP levels and active transport of glycine, L-lysine and L-leucine were studied in rat jejunum in vitro. Furthermore, the effects on lysine and glycine incorporation into mucosal protein and on mucosal cell volume were investigated. Elevation of intestinal mucosal cyclic AMP to threefold control levels by 10 mumol 1(-1) forskolin was accompanied by increased absorption of glycine (+33%), L-leucine (+72%) and L-lysine (+188%), as determined in a three compartment model suitable to measure active transport. Increased intracellular accumulation could be demonstrated for lysine as a transport substrate. Accordingly, using a dual label method, calculated values for uphill transport of lysine at the site of the brush border membrane were markedly enhanced. Forskolin up to 10 mumol 1(-1) had no effects on the fraction of lysine or glycine incorporated into TCA-precipitable proteins of jejunal absorptive cells. Serosal to mucosal transfer, as well as basolateral entry into mucosal cells remained unchanged for all three amino acids. Likewise, intracellular fluid space, calculated from distribution spaces for 14C-inulin and 3H2O as well as the response of cellular volume to an osmotic gradient were not affected by forskolin. As comparable stimulatory effects of forskolin on active hexose transport were reported earlier, it is suggested that forskolin - known to inhibit sodium-coupled fluid absorption - may stimulate active transport by enhancing sodium availability for sodium dependent intestinal cotransporters in general.