PCR-based diagnosis of Naegleria sp. infection in formalin-fixed and paraffin-embedded brain sections

We developed a real-time PCR which allowed the highly sensitive detection of Naegleria fowleri in histological brain tissue sections from experimentally infected mice. This genus-specific small-subunit (18S) rRNA gene-based PCR can complement conventional (immuno-) histology for the diagnosis of primary amoebic meningoencephalitis in paraffin-embedded brain necropsy specimens that had been fixed in formalin buffered with phosphate-buffered saline.     

Protective DNA vaccination against myelin oligodendrocyte glycoprotein is overcome by C3d in experimental autoimmune encephalomyelitis

Complement receptor 2 (CR2) and its physiological ligand, C3d, known for its molecular adjuvant property on the immune response, exhibit opposite effects with regard to autoimmunity. Although CR2 has been implicated in maintaining self-tolerance, recent studies reported a role for C3d signaling to CR2 in tolerance breakdown to self-antigens and the initiation of inflammatory autoimmune pathologies. In the present study, we have investigated the effect of C3d in a model of tolerogenic DNA vaccination encoding the myelin oligodendrocyte glycoprotein (MOG-DNA) which protected mice from the induction of an experimental autoimmune encephalomyelitis (EAE). We show that fusing two or three copies of C3d to MOG overcomes the protective effect of DNA vaccination. Multimeric C3d was able to revert the unresponsiveness state of specific T cells induced by MOG-DNA, independently of a modification in the Th1/Th2 cytokine pattern. Interestingly, the adjuvant effect of C3d was not sufficient to boost the anti-MOG antibody response after DNA vaccination. These findings suggest that C3d might be involved in self-tolerance breakdown and could contribute to the pathogenesis of central nervous system autoimmune disorders.     

Measurement of reaching kinematics and prehensile dexterity in nonhuman primates

A modified "Klüver" or dexterity board was developed to assess fine control of hand and digit movements by nonhuman primates during the acquisition of small food pellets from wells of different diameter. The primary advantages of the new device over those used previously include standardized positioning of target food pellets and controlled testing of each hand without the need for restraints, thereby allowing the monkey to move freely about the cage. Three-dimensional video analysis of hand motion was used to provide measures of reaching accuracy and grip aperture, as well as temporal measures of reach duration and food-pellet manipulation. We also present a validated performance score based on these measures, which serves as an indicator of successful food-pellet retrieval. Tests in three monkeys show that the performance score is an effective measure with which to study fine motor control associated with learning and handedness. We also show that the device and performance scores are effective for differentiating the effects of localized injury to motor areas of the cerebral cortex.     

Streptozotocin-induced diabetes can be reversed by hepatic oval cell activation through hepatic transdifferentiation and pancreatic islet regeneration

Hepatic oval cells have shown the potential to transdifferentiate into insulin-producing cells when cultured with high glucose concentrations. However, it remains unknown whether the oval cells can contribute to insulin production in diabetic mice. In this study, our aim was to investigate the response of activated hepatic oval cells to hyperglycemic conditions. C57BL/6 mice were fed a diet containing 0.1% 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) for 4 weeks to activate the hepatic oval cell population before inducing hyperglycemia with streptozotocin (STZ). Despite the initial hyperglycemia (341+/-15 mg/dl), the blood glucose levels of DDC-STZ-treated mice were significantly improved within 6 weeks (185+/-12 mg/dl). During the initial hyperglycemic stage, DDC-STZ-treated livers expressed pancreatic developmental, endocrine and exocrine genes. Hepatic insulin production was confirmed by immunohistochemistry and ELISA. These results suggested that transdifferentiated hepatic oval cell population contributed to the amelioration of hyperglycemia. We additionally determined that DDC-STZ-treated pancreata played a critical role in complete reversal of hyperglycemia as evidenced by extensive beta-cell regeneration and increase of pancreatic insulin content after STZ treatment, which is rarely observed in other adult STZ models. Reversal of hyperglycemia in this model seems to be accomplished by biphasic insulin augmentation, first by hepatic transdifferentiation, and followed by endogenous beta-cell regeneration in the pancreas. The DDC-STZ treatment provides a novel injury model for better understanding of the functional behavior of hepatic and pancreatic stem/progenitor cell population under hyperglycemic condition, which may yield critical information for developing beta-cell-based therapies to treat diabetes.