Intrahepatic growth and maturation of Gnathostoma turgidum in the natural definitive opossum host, Didelphis virginiana.

Gnathostoma turgidum is a gastric nematode parasite of opossums found in the Americas. We recently found that G. turgidum juveniles appear in the liver of the opossums where they become mature adults and almost synchronously move to the stomach during certain months of the year, suggesting the importance of the liver for the growth and maturation of this species in the final hosts. In this study we attempted to detect G. turgidum larvae in the liver of opossums, Didelphis virginiana that are the natural final hosts. The results show that tiny (<3mm in length) third stage larvae (L3) appeared in the liver of opossums around November and December. Also in the liver, we found large L3 of up to about 10mm in length together with juveniles and mature adults from February to March. In spite of their length, large L3 have 4 rows of hooklets, and their gonads remained undeveloped. Morphological features of the small and large L3 of G. turgidum are described including scanning electron microscope images. The seasonal switching of the several growth stages of G. turgidum from small L3 to adult worms in the liver and eventual migration to the stomach in opossums suggests the unique feature of G. turgidum utilizing the liver as the maturation site.

Discovery of an endemic area of Gnathostoma turgidum infection among opossums, Didelphis virginiana, in Mexico.

Gnathostomosis, caused by Gnathostoma binucleatum, is a serious public health issue in Mexico. Although 2 other Gnathostoma spp., G. turgidum and G. lamothei, have been found in wild animals, their natural life cycle or their relation to human disease remains unclear. While we were conducting an epidemiological survey on Gnathostoma spp. in Sinaloa State, Mexico, we found an endemic area for G. turgidum in common opossums, Didelphis virginiana, located in Tecualilla, Sinaloa. The species identification was carried out by morphological and molecular biological methods. This is the first record of an endemic area for G. turgidum infection in opossums, D. virginiana, in the Americas.

Effect of the 17beta-aminoestrogen pentolame on bone mineral levels in ovariectomized rats.

Estrogens are fundamental to maintaining bone mineral balance. 17beta-aminoestrogens produce low estrogenic effects through ERalpha and ERbeta receptors, however their effects on bone tissue are unknown. This work evaluates the effects of the 17beta-aminoestrogen pentolame (AEP) and estradiol (E2) on the mineral profile of rat femur. Six months after ovariectomy (Ovx) adult Wistar rats (200-250g) were treated every third day for 30 days with subcutaneous (s.c.) injections of E2 (1, 10, 100 microg/kg), AEP (1, 10, 100, 500 microg/kg) or vehicle (propylenglycol; 1 ml/kg). After treatment, femur samples were prepared and Ca, P, Mg, Si, Fe, S, Na, K, and Cl concentration profiles were estimated using an X-ray analysis system coupled to an scanning electron microscope. Ovariectomy significantly decreased Ca, P, Mg and Si and increased Fe and S. Treatment with E2 restored Ca, P, Mg, and Si to the control values and decreased Fe and S in a dose dependent manner. AEP restored the levels of Ca, P, Mg and Si at all doses administered. AEP increased the levels of Fe and restored S to the basal level. The other minerals showed great variability and no significant differences were detected. Our results indicate differential action of AEP related to E2 in the restitution of bone mineral content.

Ependymal epithelium disruption after vanadium pentoxide inhalation. A mice experimental model.

The blood-brain barrier (BBB) protects the CNS against chemical insults. Regulation of blood-brain tissue exchange is accomplished by ependymal cells, which possess intercellular tight junctions. Loss of BBB function is an etiologic component of many neurological disorders. Vanadium (V) is a metalloid widely distributed in the environment and exerts potent toxic effects on a wide variety of biological systems. The current study examines the effects of Vanadium pentoxide (V2O5) inhalation in mice ependymal epithelium, through the analysis of the brain metal concentrations and the morphological modifications in the ependymal cells identified by scanning and transmission electron microscopy after 8 weeks of inhalation, in order to obtain a possible explanation about the mechanisms that V uses to enter and alter the CNS. Our results showed that V2O5 concentrations increase from the first week of study, stabilizing its values during the rest of the experiment. The morphological effects included cilia loss, cell sloughing and ependymal cell layer detachment. This damage can allow toxicants to modify the permeability of the epithelium and promote access of inflammatory mediators to the underlying neuronal tissue causing injury and neuronal death. Thus, understanding the mechanisms of BBB disruption would allow planning strategies to protect the brain from toxicants such as metals, which have increased in the atmosphere during the last decades and constitute an important health problem.