Terahertz photometer to observe solar flares in continuum

Solar observations at sub-THz frequencies detected a new flare spectral component peaking in the THz range, simultaneously with the well known microwaves component, bringing challenging constraints for interpretation. Higher THz frequencies observations are needed to understand the nature of the mechanisms occurring in flares. A THz photometer system was developed to observe outside the terrestrial atmosphere on stratospheric balloons or satellites, or at exceptionally transparent ground stations. The telescope was designed to observe the whole solar disk detecting small relative changes in input temperature caused by flares at localized positions. A Golay cell detector is preceded by low-pass filters to suppress visible and near IR radiation, a band-pass filter, and a chopper. A prototype was assembled to demonstrate the new concept and the system performance. It can detect temperature variations smaller than 1 K for data sampled at a rate of 10/second, smoothed for intervals larger than 4 seconds. For a 76 mm aperture, this corresponds to small solar burst intensities at THz frequencies. A system with 3 and 7 THz photometers is being built for solar flare observations on board of stratospheric balloon missions.Comment: 11 pages, 8 figures, accepted by Journal of Infrared, Millimeter, and Terahertz Waves, 9 December 201

Novel insights into the mechanisms mediating the local antihypertrophic effects of cardiac atrial natriuretic peptide: role of cGMP-dependent protein kinase and RGS2

Cardiac atrial natriuretic peptide (ANP) locally counteracts cardiac hypertrophy via the guanylyl cyclase-A (GC-A) receptor and cGMP production, but the downstream signalling pathways are unknown. Here, we examined the influence of ANP on β-adrenergic versus Angiotensin II (Ang II)-dependent (Gs vs. Gαq mediated) modulation of Ca2+i-handling in cardiomyocytes and of hypertrophy in intact hearts. L-type Ca2+ currents and Ca2+i transients in adult isolated murine ventricular myocytes were studied by voltage-clamp recordings and fluorescence microscopy. ANP suppressed Ang II-stimulated Ca2+ currents and transients, but had no effect on isoproterenol stimulation. Ang II suppression by ANP was abolished in cardiomyocytes of mice deficient in GC-A, in cyclic GMP-dependent protein kinase I (PKG I) or in the regulator of G protein signalling (RGS) 2, a target of PKG I. Cardiac hypertrophy in response to exogenous Ang II was significantly exacerbated in mice with conditional, cardiomyocyte-restricted GC-A deletion (CM GC-A KO). This was concomitant to increased activation of the Ca2+/calmodulin-dependent prohypertrophic signal transducer CaMKII. In contrast, β-adrenoreceptor-induced hypertrophy was not enhanced in CM GC-A KO mice. Lastly, while the stimulatory effects of Ang II on Ca2+-handling were absent in myocytes of mice deficient in TRPC3/TRPC6, the effects of isoproterenol were unchanged. Our data demonstrate a direct myocardial role for ANP/GC-A/cGMP to antagonize the Ca2+i-dependent hypertrophic growth response to Ang II, but not to β-adrenergic stimulation. The selectivity of this interaction is determined by PKG I and RGS2-dependent modulation of Ang II/AT1 signalling. Furthermore, they strengthen published observations in neonatal cardiomyocytes showing that TRPC3/TRPC6 channels are essential for Ang II, but not for β-adrenergic Ca2+i-stimulation in adult myocytes

Molecular detection of Ehrlichia canisand Anaplasma platys in dogs in Southern Brazil

The aims of this study were to determine the occurrence of Anaplasma platys and Ehrlichia canis infection in dogs in Porto Alegre, Southern Brazil; and to investigate their association with hematological abnormalities. Serum samples from 196 dogs were first tested using dot-ELISA for antibodies against Anaplasma spp. and Ehrlichia canis. Peripheral blood samples from 199 dogs were subjected to 16S rRNA nested PCR (nPCR) for A. platys and E. canis, followed by DNA sequencing to ensure pathogen identity. A total of 19/196 samples (9.69%) were positive for Anaplasma spp. using ELISA and 28/199 (14.07%) samples were positive for A. platys by nested PCR. All the dog samples were negative for E. canis, both in anti-E. canis antibody tests and in nested PCR. There were no significant differences in hematological parameters between A. platys-PCR positive and negative dogs and Anaplasma spp. serologically positive dogs, except for basophil counts, which were higher in nPCR-positive dogs. This is the first report showing A. platys presence in dogs in Southern Brazil. In conclusion, hematological parameters may not be sufficient to diagnose A. platys infection in dogs in Southern Brazil, probably due either to low pathogenicity or to chronic infection. On the other hand, E. canis may either have very low occurrence or be absent in dogs in Porto Alegre.O objetivo deste estudo foi determinar a ocorrência de Anaplasma platys e Ehrlichia canis em cães de Porto Alegre, sul do Brasil, sua detecção molecular e associação com anormalidades hematológicas. Amostras séricas de 196 cães foram inicialmente triadas por dot-ELISA para a presença de anticorpos contra Anaplasma spp. e Ehrlichia canis. Amostras de sangue periférico de 199 cães foram submetidas à nested PCR (16S rRNA) para A. platys e E. canis, seguido de sequenciamento do DNA para confirmar a identidade do agente. Do total, 19/196 (9,69%) amostras foram positivas para Anaplasma spp. por dot-ELISA e 28/199 (14,07%) por nPCR. Todas as amostras dos cães foram negativas para E. canis no teste sorológico anti-E. canis e também na nPCR. Não houve diferença significativa nos parâmetros hematológicos, exceto a contagem de basófilos, que apresentou valores mais altos em cães positivos na nPCR para A. platys. Este é o primeiro relato da presença de A. platys no Rio Grande do Sul, e a primeira detecção molecular do agente no sul do Brasil. Em conclusão, parâmetros hematológicos não são suficientes para diagnosticar a infecção por A. platys em cães, provavelmente devido sua baixa patogenicidade ou infecção crônica. Por outro lado, E. canis parece ter ocorrência baixa ou mesmo nula em cães de Porto Alegre