Dose–response and histopathological study,with special attention to the hypophysis,of the differential effects of domoic acid on rats and mice

The effects of the neurotoxin domoic acid (DA) in the central nervous system of rodents (essentially rats and mice) after intraperitoneal administration have been profusely studied in the past. These observations have shown that the toxin induces similar symptoms and pathology in both species, but the lethality varies greatly. This article addresses the common and specific histopathological effects in rats and mice and the difference in sensitivity of these species to DA. Various sublethal and lethal doses were employed in mice (from 3 mg/kg to 8 mg/kg) to observe their neurotoxicity by using different histological techniques, and these results were compared with the pathological effects after the administration of LD50 in rats (2.5 mg/kg). Additionally we also detected the presence of this toxin in various tissues by means of immunohistochemistry. Our results showed that rats are more vulnerable than mice to the neurotoxic effects of DA after intraperitoneal inoculation: lethality was extremely high in rats and the toxin produced hippocampal damage in rats surviving the intoxication, while lesions were not observed in DA‐inoculated mice. As for similarities between rats and mice, both displayed similar clinical signs and in both the toxin was detected in the hypophysis by immunohistochemistry, a brain region not reported to date as target of the toxin. Microsc. Res. Tech. 78:396–403, 2015. © 2015 Wiley Periodicals, Inc.     

Proliferation study and microscopy evaluation on the effects of tannic acid in human fetal osteoblast cell line (hFOB 1.19)

Tannic acid (TA) is a phenolic compound that might act directly on osteoblast metabolism. The study was performed to investigate the effects of TA on the proliferation, mineralization, and morphology of human fetal osteoblast cells (hFOB 1.19). The cells were divided into TA‐treated, untreated, and pamidronate‐treated (control drug) groups. Half maximal effective concentration (EC₅₀) values for TA and pamidronate were measured using MTT assay. The EC₅₀ of hFOB 1.19 cells treated with TA was 2.94 M. This concentration was more effective compared to the pamidronate (15.27 M). Cell proliferation assay was performed to compare cell viability from Day 1 until Day 14. The morphology of hFOB 1.19 was observed via inverted microscope and scanning electron microscope. Calcium (Ca) and phosphate (P) were assessed using energy‐dispersive X‐ray (EDX) analysis. Furthermore, the mineralization of hFOB 1.19 was determined by von Kossa staining (P depositions) and Alizarin Red S staining (Ca depositions). The number of cells treated with TA was significantly higher than the two control groups at Day 10 and Day 14. The morphology of cells treated with TA was uniformly fusiform‐shaped with filopodia extensions. Besides, globular‐like structures of deposited minerals were observed in the TA‐treated group. In line with other findings, EDX spectrum analysis confirmed the presence of Ca and P. The cells treated with TA had significantly higher percentage of both minerals at Day 3 and Day 10 compared to the two control groups. In conclusion, TA enhances cell proliferation and causes cell morphology changes, as well as improved mineralization.     

Centrifugation of bacterial cells on slide surface improves the spatial distribution, cell recovery and reduces the time of enumeration for fluorescence in situ hybridization

Fluorescence in situ hybridization (FISH), which is used for the enumeration of bacteria in various ecosystems including the human intestinal tract, has several limitations. One of the major problems encountered is the uneven distribution of bacterial cells on the slide surface, which increases the coefficient of variation between repetitions and thereby increase the time required for enumeration. In order to improve the spatial distribution, we designed a centrifugation device, which allows the direct centrifugation of bacterial cells onto the slide surface. Another problem is the loss of bacterial cells during the hybridization procedure. This leads to an underestimation of the true cell numbers in the sample. To overcome this problem we tested the use of silanized or chrome gelatine coated slides. Our study indicates that the use of the centrifugation device in conjunction with chrome gelatine coated slides highly improves the quality of enumeration data obtained by manual and automated microscopic counting and shortens the time of analysis.