A Comparative Study of the Distribution and Density of Retinal Ganglion Cells and Visual Acuity in Bothrops Snakes with Differences in the Habitat Use

Purpose: The density and distribution of neurons in retinas of vertebrates are associated with specific behaviors and species ecology. The visual system of snakes has adaptations to the species’ habitats, circadian rhythm, and foraging strategies. A previous study revealed a ventral area centralis in a terrestrial snake and a visual streak in a close related arboreal species. In this study, we compared the distribution of ganglion cell layer (GCL) cells in retinas of Viperidae snakes from the genus Bothrops, with differences in the habitat use, namely the arboreal B. insularis, and the semi-arboreal species B. jararaca and B. sazimai. Methods: Three individuals of each species were euthanized with Thionembutal (100 mg/kg). The eyes were enucleated and retinas were dissected and fixed in 4% paraformaldehyde. Retinas were wholemounted and Nissl stained. The density of GCL cells was estimated using a stereological approach with the Stereo Investigator software (MicroBrightField), and isodensity maps were obtained using OriginPro 8.5.1. Visual acuity values were estimated based on the peak density of GCL cells and the eyes focal length. Results: We observed a poorly defined horizontal streak in retinas of the arboreal B. insularis, with higher density in the central retina, while in the semi-arboreal B. jararaca and B. sazimai there were no defined retinal specializations, and the peak cell densities were located in the temporal region. The mean cell density was 4,405 ± 735 cells/mm2 in B. insularis, 4,606 ± 335 cells/mm2 in B. sazimai, and 4,881 ± 746cells/mm2 in B. jararaca. The estimated spatial resolutions were similar among the species and varied from 2.0 to 2.2 cycles per degree. Conclusions: These findings reinforce the hypothesis that retinal specializations are associated with habitat use in snakes. A visual streak may assist in locomotion and hunting among branches, as indicated by the distribution of cells in B. insularis. On the other hand, peak GCL cell density in the temporal retina may facilitate striking behavior in the species that forage on the ground

Schistosoma mansoni Eggs in Spleen and Lungs, Mimicking Other Diseases

In the global village, clinicians should open their “clinical landscape” to a number of diseases they have little, if any, familiarity with. Moreover, some of them may present with uncommon, atypical presentations that may be mistaken for other disease

Caco-2 cell acquisition of dietary iron(III) invokes a nanoparticulate endocytic pathway

Dietary non-heme iron contains ferrous [Fe(II)] and ferric [Fe(III)] iron fractions and the latter should hydrolyze, forming Fe(III) oxo-hydroxide particles, on passing from the acidic stomach to less acidic duodenum. Using conditions to mimic the in vivo hydrolytic environment we confirmed the formation of nanodisperse fine ferrihydrite- like particles. Synthetic analogues of these (~ 10 nm hydrodynamic diameter) were readily adherent to the cell membrane of differentiated Caco-2 cells and internalization was visualized using transmission electron microscopy. Moreover, Caco-2 exposure to these nanoparticles led to ferritin formation (i.e., iron utilization) by the cells, which, unlike for soluble forms of iron, was reduced ( p =0.02) by inhibition of clathrin-mediated endocytosis. Simulated lysosomal digestion indicated that the nanoparticles are readily dissolved under mildly acidic conditions with the lysosomal ligand, citrate. This was confirmed in cell culture as monensin inhibited Caco-2 utilization of iron from this source in a dose dependent fashion ( p <0.05) whilet soluble iron was again unaffected. Our findings reveal the possibility of an endocytic pathway for acquisition of dietary Fe(III) by the small intestinal epithelium, which would complement the established DMT-1 pathway for soluble Fe(II

Failure of malaria chemoprophylaxis with mefloquine in an oversize traveller to Mozambique

A case of failure of mefloquine prophylaxis in an oversize traveller, who correctly took the drug. This case seems to be attributed to mefloquine resistance, however it is suggested that mefloquine dosage should be modulated by body weight, as is already indicated by some authorities

Factors associated with cesarean sections in a public hospital in Rio de Janeiro, Brazil Fatores associados à realização de cesáreas em uma maternidade pública do Município do Rio de Janeiro, Brasil

Brazil has one of the world's highest cesarean section rates. Contributing factors include the organization of obstetric practice, physicians' attitudes, and women's preferences and decisions. This study aimed to identify factors associated with cesarean sections in a public maternity hospital in Rio de Janeiro. A case-control study was conducted with 231 cesarean sections (cases) and 230 vaginal deliveries (controls). Hierarchical logistic regression analysis was performed, based on a conceptual model. Factors associated with increased odds of cesarean section were: primiparity; mother's age 20-34; last birth by cesarean; cervical dilatation < 3cm at admission; patient request; daytime birth; male attending obstetrician; obstetrician on duty for more than 24 hours a week; obstetrician with private practice; gestational hypertension; non-cephalic presentation; and gestational age > 41 weeks. Factors associated with lower odds of cesarean were: gestational age < 37 weeks; leaving home with signs of labor, use of oxytocin; and amniotomy. In this hospital, interventions aimed to modify the above-mentioned factors can help lower the cesarean rate.<br>O Brasil apresenta uma das maiores proporções de cesáreas do mundo. Fatores contribuintes para este fenômeno incluem organização da prática obstétrica, atitudes dos obstetras, preferências e decisões das mulheres. Com o objetivo de identificar fatores associados à realização de cesáreas, foi realizado estudo de caso-controle em uma maternidade pública do Município do Rio de Janeiro. Incluíram-se 231 partos por cesárea (casos) e 230 partos vaginais (controles). Utilizou-se análise multivariada com regressão logística, as variáveis foram incluídas no modelo obedecendo à ordem hierárquica definida em modelo conceitual. Fatores associados à maior chance de cesárea: primiparidade; idade 20-34 anos; último parto por cesárea; dilatação cervical < 3cm na admissão; preferência da mulher por cesárea; horário diurno; parto realizado por obstetra do sexo masculino; obstetra que trabalha mais de 24 horas semanais de plantão; obstetra com consultório particular; hipertensão; apresentação fetal não-cefálica; e idade gestacional > 41 semanas. Fatores associados à menor chance de cesárea: prematuridade; sinais de trabalho de parto ao sair de casa; uso de ocitocina e amniotomia. Propostas de modificação nos fatores estudados podem contribuir para redução da proporção de cesáreas