Quinolinic acid lesions of the pedunculopontine nucleus impair sleep architecture, but not locomotion, exploration, emotionality or working memory in the rat.

Anatomical and functional studies have shown that the NADPH-diaphorase-positive cholinergic neurons of the pedunculopontine nucleus (PPN) send projections to several areas in the brain. The purpose of this work was to investigate whether bilateral lesions with quinolinic acid, a neurotoxin with greater selectivity for NADPH-diaphorase-positive neurons, aimed at the compact portion of the PPN would affect the performance of adaptive behaviors, such as sleep, locomotion, and spontaneous alternation. Lesioned animals were divided in a low lesion group (LL, <50% neuron loss) and a high lesion group (HL, ≥50% neuron loss). The LL animals did not show any significant changes in sleep patterns, as compared to controls. In contrast, the HL group showed a significant increase in the number of REM sleep periods, and a reduction of REM sleep average duration, but did not differ in the total time spent in REM sleep. HL animals also showed an increase in the number of SWS periods, though wakefulness parameters did not show significant alterations. The duration and number of both REM and SWS sleep episodes were significantly correlated with the number of NADPH-diaphorase-positive neurons in the PPN. The short-term habituation pattern of locomotion, the vertical exploratory activity, as well as the thigmotaxis (an index of emotionality), displayed by LL and HL rats in a novel environment were similar to those of control animals. Likewise, there were no significant differences in spontaneous alternation among the groups. Our results indicate that quinolinic acid lesions of NADPH-diaphorase-positive cholinergic neurons localized in the posterior region of the PPN disrupt normal sleep structure, while motor activity and spontaneous alternation remain unaffected.

Folate, homocysteine, interleukin-6, and tumor necrosis factor alfa levels, but not the methylenetetrahydrofolate reductase C677T polymorphism, are risk factors for schizophrenia.

The methylenetetrahydrofolate reductase (MTHFR) C677T mutation has been associated to high homocysteine levels and schizophrenia. Since cytokines are altered in schizophrenia and increments of homocysteine could promote an inflammatory response, it was investigated whether interleukin-6 (IL-6) and tumor necrosis factor alfa (TNFalpha) levels are modulated by the MTHFR genotype. Serum levels of TNFalpha, IL-6, B(12), homocysteine, folate and red blood cell (RBC) folate as well as the MTHFR genotype were determined in a group of schizophrenic patients and compared to those of a control group. RBC folate levels were reduced and homocysteine and the two cytokines' concentrations were elevated in all patients as compared to controls. RBC folate in both heterozygous (CT) and homozygous (TT) patients was significantly different to that of their respective control groups. Homocysteine levels found in patients were significantly higher than those found in controls, only in individuals carrying the TT genotype. Cytokine levels were augmented in the group of patients irrespective of the genotype, and significant differences were found in all cases, except for TNFalpha levels in those subjects carrying the CC genotype. After adjusting for sex, low levels of RBC folate, high levels of homocysteine, both medium and high levels of TNFalpha and high IL-6 levels were associated with schizophrenia. MTHFR genotype was not a risk factor for developing the disease, although a larger sample is required to confirm this finding.

Evaluation of depressive symptoms and sleep alterations in college students.

BACKGROUND: Increasing evidence suggests that sleep alterations could favor subsequent depression development. In order to identify the simultaneous occurrence of these parameters in young people, in this work we evaluated the prevalence of depressive symptoms, sleep habits, and possible sleep disturbances in college students. METHODS: Beck Depression Inventory (BDI), Epworth Sleepiness Scale (ESS), and a Sleep Habits Questionnaire were applied to students registered at the Autonomous University of Yucatan, Merida (mean age 20.2 +/- 2.6 years). The final sample was composed of 340 (53%) women and 298 (47%) men. Reliability of the BDI and ESS was assessed by Cronbach's alpha method. RESULTS: Taking 10 as ESS cut-off point, it was found that 31.6% of the students had a high level of sleepiness. Students with depressive symptoms had a greater number of days with somnolence during class (p <0.05) and perceived that this affected their academic performance at a higher level (p <0.001) than the students without symptoms. In comparison to subjects without depressive symptoms, students with those symptoms rated their sleep quality as poor (p <0.001), perceived a greater latency to initiate sleep after going to bed (p <0.03), and experienced a greater number of awakenings (p <0.04). CONCLUSIONS: We found diverse sleep alterations in a large proportion of the studied subjects, which were more severe in those who showed depressive symptoms. Educating students for appropriate sleep hygiene and encouraging them to seek professional advice to treat sleep disturbances may be useful to prevent depression.

Prevalencia de Dirofilaria immitis en perros callejeros de la ciudad de Mérida, Yucatán, México / Prevalence of Dirofilaria immitis in stray dogs in the city of Merida, Yucatan, Mexico

Se estudió la dirofilariasis canina en la ciudad de Mérida Yucatán, en el sureste de México, con el objetivo de determinar su prevalencia y comparar la efectividad de la prueba de gota gruesa y Knott modificada , con la presencia de parásitos adultos en la necropsia. prevaleció Dirofilaria immitis en 6.54 por ciento y Dipetalonema reconditum en 7.47 por ciento. La prueba de Knott modificada detectó 11 casos positivos a microfiliarias circulantes y la prueba de gota gruesa solamente detectó 3 casos. Se encontraron 2 casos de filariasis mixta. Cinco animales fueron positivos a parásitos adultos en la necropsia y 7 positivos a microfiliarias circulantes; sin embargo, 2 casos con parásitos adultos en la necropsia no pudieron ser detectados por la técnica de knott modificada, y 2 casos positivos a Knott modificada no presentaron parásitos adultos a la necropsia. Se presentó un promedio de 6 parásitos adultos por cada positivos; los parásitos fueron localizados en distintas partes del corazón. Se hallaron 3 casos positivos a larvas de Dipetalonema reconditum en la orina, lo que representa 5.54 por ciento de positividad. Se concluye que para el diagnóstico de la dirofilariasis canina es necesario la detección de microfilarias en sangre y acompañarse de pruebas complementarias