Unbalanced Occlusion Modifies the Pattern of Brain Activity During Execution of a Finger to Thumb Motor Task.

In order to assess possible influences of occlusion on motor performance, we studied by functional magnetic resonance imaging (fMRI) the changes in the blood oxygenation level dependent (BOLD) signal induced at brain level by a finger to thumb motor task in a population of subjects characterized by an asymmetric activation of jaw muscles during clenching (malocclusion). In these subjects, appropriate occlusal correction by an oral orthotic (bite) reduced the masticatory asymmetry. The finger to thumb task was performed while the subject's dental arches were touching, in two conditions: (a) with the teeth in direct contact (Bite OFF) and (b) with the bite interposed between the arches (Bite ON). Both conditions required only a very slight activation of masticatory muscles. Maps of the BOLD signal recorded during the movement were contrasted with the resting condition (activation maps). Between conditions comparison of the activation maps (Bite OFF/Bite ON) showed that, in Bite OFF, the BOLD signal was significantly higher in the trigeminal sensorimotor region, the premotor cortex, the cerebellum, the inferior temporal and occipital cortex, the calcarine cortex, the precuneus on both sides, as well as in the right posterior cingulate cortex. These data are consistent with the hypothesis that malocclusion makes movement performance more difficult, leading to a stronger activation of (a) sensorimotor areas not dealing with the control of the involved body part, (b) regions planning the motor sequence, and (c) the cerebellum, which is essential in motor coordination. Moreover, the findings of a higher activation of temporo-occipital cortex and precuneus/cingulus, respectively, suggest that, during malocclusion, the movement occurs with an increased visual imagery activity, and requires a stronger attentive effort.

Parasite prevalence in a village in Burkina Faso: the contribution of new techniques.

INTRODUCTION: Parasites are a major public health problem in developing countries. A coproparasitological and immunoparasitological study was conducted in Burkina Faso, in the rural village of Touguri, in November and December 2011. The coproparasitologic analysis was conducted in the pediatric population and seroprevalence surveys were conducted in the adult population to research intestinal, blood, and helminth parasites. METHODOLOGY: The coproparasitologic study was performed on stool samples using two diagnostic methods - standard microscopy and the FLOTAC technique. The total of 49 stool samples analyzed were obtained from children between two months and eleven years of age. The serology study was carried out to evaluate the prevalence of P. falciparum, Echinococcus spp., Tenia solium, and A. lumbricoides using different immunological techniques such as ELISA and Western Blot techniques. The study population included 85 adult patients between 15 and 70 years of age. RESULTS: Results of coproparasitological analyses showed Hymenolepis nana as the only helminth found, in 28.6% of the total number of patients. Results of serological evaluation revealed a practically null prevalence of Echinococcus, Taenia solium, and Ascaris lumbricoides, and a 77.64% prevalence of Plasmodium falciparum. CONCLUSIONS: Despite the small number (especially in terms of coprological samples) of individuals examined, this study showed that the parasite prevalence in a rural area of Burkina Faso has a significant impact in the general population, particularly in children. Another finding was that FLOTAC had a higher sensitivity than the widely used ethyl ether-based concentration technique for coprological sample analysis.

FLOTAC for the diagnosis of Hymenolepis spp. infection: proof-of-concept and comparing diagnostic accuracy with other methods.

Hymenolepis nana is the most common cestode parasitizing humans, yet it is under-diagnosed. We determined the optimal flotation solution (FS) for the diagnosis of this intestinal parasite with the FLOTAC method, and compared its diagnostic accuracy with an ether-concentration technique and the Kato-Katz method. Zinc sulphate (specific gravity 1.20) proved to be the best-performing FS. Using this FS, we detected 65 H. nana infections among 234 fixed fecal samples from Tajik and Sahrawi children (prevalence 27.8 %). The ether-concentration technique detected 40 infections (prevalence 17.1 %) in the same samples. Considering the combined results as a reference, the sensitivities of FLOTAC and ether-concentration were 95.6 % and 58.8 %, respectively. The Kato-Katz method resulted in a prevalence of only 8.7 %. In terms of eggs per gram of stool, a significantly (P <0.05) higher value was obtained with the FLOTAC and Kato-Katz techniques compared to ether-concentration. In another study carried out in China, the FLOTAC method detected six Hymenolepis diminuta infections in 302 fecal samples, whereas five samples were found positive with the Kato-Katz technique. We conclude that FLOTAC is an accurate coprodiagnostic technique for H. nana and H. diminuta, two species which join a growing list of intestinal parasites that can be reliably diagnosed by this technique.

High genetic polymorphism among Giardia duodenalis isolates from Sahrawi children.

Human giardiasis, the gastrointestinal infection caused by two genetically different groups (or assemblages) of Giardia duodenalis, is very common worldwide, and its prevalence is higher in developing countries. However, few surveys in these regions have been performed to include a genetic characterization of the parasite, which is necessary to unravel the complex epidemiology of the infection. In this work, we screened 120 faecal samples collected from Sahrawi children in 2003-2005, and found 41 (34.2%) of them to be positive, using immunofluorescent microscopy, for the presence of G. duodenalis cysts. Molecular characterization of the isolates was performed by RFLP and/or sequence analysis of the triose phosphate isomerase (tpi) and the glutamate dehydrogenase (gdh) genes. The results disclosed an unexpectedly high genetic polymorphism among isolates of both assemblages A and B, and a large percentage of the sequences (50% for the tpi gene, and 90% for the gdh gene) from assemblage B isolates characterized by the presence of overlapping nucleotide peaks at specific positions in the chromatograms, which can be attributed to mixed infections or to allelic sequence heterozygosity of single cysts. Notably, this phenomenon was not observed in sequences from assemblage A isolates. These results suggest that the genetic structure is different in isolates of assemblages A and B.