Diphenyl diselenide and diphenyl ditelluride increase the latency for 4-aminopyridine-induced chemical seizure and prevent death in mice.

In this work was investigated the effect of pre-treatment with (PhSe)(2) and (PhTe)(2) on chemical seizure and 4-aminopyridine-induced lethality in mice. Additionally, lipid peroxidation levels of whole brain after treatment with 4-aminopyridine and effect of pre-treatment with (PhSe)(2) and (PhTe)(2) on these levels were investigated. Mice were pre-treated with (PhSe)(2) or (PhTe)(2) (50, 100, or 150 micromol/kg) 30 min before 4-aminopyridine (12 mg/kg) administration. The treatment with 4-aminopyridine caused a significant incidence of seizures (clonic, tonic) and death. Pre-treatment with (PhSe)(2) and (PhTe)(2) significantly increased the latency for clonic and tonic seizures, and prevented 4-aminopyridine-induced death. Significantly, the pre-treatment with (PhSe)(2) or (PhTe)(2) increased the latency for clonic seizures in a dose-dependent manner. Additionally, a significant increase was observed in the brain lipid peroxidation level after treatment with 4-aminopyridine, which was significantly inhibited by pre-treatment with 150 micromol/kg (PhSe)(2) or (PhTe)(2). These results demonstrate that (PhSe)(2) and (PhTe)(2) counteract the harmful effects of 4-aminopyridine. It is possible that this effect results from modulation of the redox state of N-methyl-d-aspartate receptors and/or of Ca(2+) channel activity with subsequent alteration in neurotransmitter release. Importantly, this study provides evidence for anticonvulsant and antioxidant properties of (PhSe)(2) and (PhTe)(2), which indicates a neuroprotective activity of these compounds.

What determines sclerobiont colonization on marine mollusk shells?

Empty mollusk shells may act as colonization surfaces for sclerobionts depending on the physical, chemical, and biological attributes of the shells. However, the main factors that can affect the establishment of an organism on hard substrates and the colonization patterns on modern and time-averaged shells remain unclear. Using experimental and field approaches, we compared sclerobiont (i.e., bacteria and invertebrate) colonization patterns on the exposed shells (internal and external sides) of three bivalve species (Anadara brasiliana, Mactra isabelleana, and Amarilladesma mactroides) with different external shell textures. In addition, we evaluated the influence of the host characteristics (mode of life, body size, color alteration, external and internal ornamentation and mineralogy) of sclerobionts on dead mollusk shells (bivalve and gastropod) collected from the Southern Brazilian coast. Finally, we compared field observations with experiments to evaluate how the biological signs of the present-day invertebrate settlements are preserved in molluscan death assemblages (incipient fossil record) in a subtropical shallow coastal setting. The results enhance our understanding of sclerobiont colonization over modern and paleoecology perspectives. The data suggest that sclerobiont settlement is enhanced by (i) high(er) biofilm bacteria density, which is more attracted to surfaces with high ornamentation; (ii) heterogeneous internal and external shell surface; (iii) shallow infaunal or attached epifaunal life modes; (iv) colorful or post-mortem oxidized shell surfaces; (v) shell size (<50 mm2 or >1,351 mm2); and (vi) calcitic mineralogy. Although the biofilm bacteria density, shell size, and texture are considered the most important factors, the effects of other covarying attributes should also be considered. We observed a similar pattern of sclerobiont colonization frequency over modern and paleoecology perspectives, with an increase of invertebrates occurring on textured bivalve shells. This study demonstrates how bacterial biofilms may influence sclerobiont colonization on biological hosts (mollusks), and shows how ecological relationships in marine organisms may be relevant for interpreting the fossil record of sclerobionts.

Involvement of oxidative stress in the pre-malignant and malignant states of cervical cancer in women.

OBJECTIVES: To evaluate the potential role of oxidative stress in the evolution of cervical cancer, including its pre-malignant states. DESIGN AND METHODS: Erythrocytes thiobarbituric acid reactive substances (TBARS) levels, plasma vitamin C and thiol content and total blood delta-ALA-D levels were estimated in 46 untreated cervical cancer and pre-malignant patients and in 46 age-sex-matched controls. RESULTS: Erythrocytes from patients, regardless of disease state, pre-malignant (low squamous intraepithelial lesion--LSIL and high squamous intraepithelial lesion--HSIL) or cancer, showed a significant 2-3 times increase in TBARS levels (P<0.01). Plasma vitamin C was lower in the carcinoma group (P<0.01). The reactivation index of delta-aminolevulinate dehydratase (delta-ALA-D) was higher in the patient group, when compared to control (P<0.01). CONCLUSION: LSIL, HSIL or cervical cancer can be associated with changes in 3 indicators of oxidative stress: increase in erythrocyte TBARS, ALA-D reactivation index and a decrease in vitamin C content, that may play an important role in carcinogenesis.