Artificial pancreas using a personalized rule-based controller achieves overnight normoglycemia in patients with type 1 diabetes

Objective: This study assessed the efficacy of a closed-loop (CL) system consisting of a predictive rule-based algorithm (pRBA) on achieving nocturnal and postprandial normoglycemia in patients with type 1 diabetes mellitus (T1DM). The algorithm is personalized for each patient’s data using two different strategies to control nocturnal and postprandial periods. Research Design and Methods: We performed a randomized crossover clinical study in which 10 T1DM patients treated with continuous subcutaneous insulin infusion (CSII) spent two nonconsecutive nights in the research facility: one with their usual CSII pattern (open-loop [OL]) and one controlled by the pRBA (CL). The CL period lasted from 10 p.m. to 10 a.m., including overnight control, and control of breakfast. Venous samples for blood glucose (BG) measurement were collected every 20 min. Results: Time spent in normoglycemia (BG, 3.9–8.0 mmol/L) during the nocturnal period (12 a.m.–8 a.m.), expressed as median (interquartile range), increased from 66.6% (8.3–75%) with OL to 95.8% (73–100%) using the CL algorithm (P<0.05). Median time in hypoglycemia (BG, <3.9 mmol/L) was reduced from 4.2% (0–21%) in the OL night to 0.0% (0.0–0.0%) in the CL night (P<0.05). Nine hypoglycemic events (<3.9 mmol/L) were recorded with OL compared with one using CL. The postprandial glycemic excursion was not lower when the CL system was used in comparison with conventional preprandial bolus: time in target (3.9–10.0 mmol/L) 58.3% (29.1–87.5%) versus 50.0% (50–100%). Conclusions: A highly precise personalized pRBA obtains nocturnal normoglycemia, without significant hypoglycemia, in T1DM patients. There appears to be no clear benefit of CL over prandial bolus on the postprandial glycemia

Pituitary adenylyl cyclase-activating peptide: A pivotal modulator of glutamatergic regulation of the suprachiasmatic circadian clock

The circadian clock in the suprachiasmatic nucleus (SCN) of the hypothalamus organizes behavioral rhythms, such as the sleep–wake cycle, on a near 24-h time base and synchronizes them to environmental day and night. Light information is transmitted to the SCN by direct retinal projections via the retinohypothalamic tract (RHT). Both glutamate (Glu) and pituitary adenylyl cyclase-activating peptide (PACAP) are localized within the RHT. Whereas Glu is an established mediator of light entrainment, the role of PACAP is unknown. To understand the functional significance of this colocalization, we assessed the effects of nocturnal Glu and PACAP on phasing of the circadian rhythm of neuronal firing in slices of rat SCN. When coadministered, PACAP blocked the phase advance normally induced by Glu during late night. Surprisingly, blocking PACAP neurotransmission, with either PACAP6–38, a specific PACAP receptor antagonist, or anti-PACAP antibodies, augmented the Glu-induced phase advance. Blocking PACAP in vivo also potentiated the light-induced phase advance of the rhythm of hamster wheel-running activity. Conversely, PACAP enhanced the Glu-induced delay in the early night, whereas PACAP6–38 inhibited it. These results reveal that PACAP is a significant component of the Glu-mediated light-entrainment pathway. When Glu activates the system, PACAP receptor-mediated processes can provide gain control that generates graded phase shifts. The relative strengths of the Glu and PACAP signals together may encode the amplitude of adaptive circadian behavioral responses to the natural range of intensities of nocturnal light.

Effects of Short- and Long-Term Elevated CO2 on the Expression of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Genes and Carbohydrate Accumulation in Leaves of Arabidopsis thaliana (L.) Heynh.1

To investigate the proposed molecular characteristics of sugar-mediated repression of photosynthetic genes during plant acclimation to elevated CO2, we examined the relationship between the accumulation and metabolism of nonstructural carbohydrates and changes in ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) gene expression in leaves of Arabidopsis thaliana exposed to elevated CO2. Long-term growth of Arabidopsis at high CO2 (1000 μL L−1) resulted in a 2-fold increase in nonstructural carbohydrates, a large decrease in the expression of Rubisco protein and in the transcript of rbcL, the gene encoding the large subunit of Rubisco (approximately 35–40%), and an even greater decline in mRNA of rbcS, the gene encoding the small subunit (approximately 60%). This differential response of protein and mRNAs suggests that transcriptional/posttranscriptional processes and protein turnover may determine the final amount of leaf Rubisco protein at high CO2. Analysis of mRNA levels of individual rbcS genes indicated that reduction in total rbcS transcripts was caused by decreased expression of all four rbcS genes. Short-term transfer of Arabidopsis plants grown at ambient CO2 to high CO2 resulted in a decrease in total rbcS mRNA by d 6, whereas Rubisco content and rbcL mRNA decreased by d 9. Transfer to high CO2 reduced the maximum expression level of the primary rbcS genes (1A and, particularly, 3B) by limiting their normal pattern of accumulation through the night period. The decreased nighttime levels of rbcS mRNA were associated with a nocturnal increase in leaf hexoses. We suggest that prolonged nighttime hexose metabolism resulting from exposure to elevated CO2 affects rbcS transcript accumulation and, ultimately, the level of Rubisco protein.

Cloning of an arylalkylamine N-acetyltransferase (aaNAT1) from Drosophila melanogaster expressed in the nervous system and the gut.

In insects, neurotransmitter catabolism, melatonin precursor formation, and sclerotization involve arylalkylamine N-acetyltransferase (aaNAT, EC 2.3.1.87) activity. It is not known if one or multiple aaNAT enzymes are responsible for these activities. We recently have purified an aaNAT from Drosophila melanogaster. Here, we report the cloning of the corresponding aaNAT cDNA (aaNAT1) that upon COS cell expression acetylates dopamine, tryptamine, and the immediate melatonin precursor serotonin. aaNAT1 represents a novel gene family unrelated to known acetyl-transferases, except in two weakly conserved amino acid motifs. In situ hybridization studies of aaNAT1 mRNA in embryos reveal hybridization signals in the brain, the ventral cord, the gut, and probably in oenocytes, indicating a broad tissue distribution of aaNAT1 transcripts. Moreover, in day/ night studies we demonstrate a diurnal rhythm of melatonin concentration without a clear-cut change in aaNAT1 mRNA levels. The data suggest that tissue-specific regulation of aaNAT1 may be associated with different enzymatic functions and do not exclude the possibility of additional aaNAT genes.

Nocturnality and species survival.

Surveys of butterfly and moth diversity in tropical forest fragments suggest that nocturnality confers a dispersal, and possibly a survival, advantage. The butterfly faunas of smaller fragments were depauperate; in contrast, the species richness of nocturnal moths was similar in all fragments and even in pasture. The lack of correlation between butterfly and moth species richness among fragments (r2 = 0.005) is best explained by movements of moths at night when ambient conditions in forest and pasture are most similar; butterflies face substantial daytime temperature, humidity, and solar radiation barriers. This interpretation is supported by information on birds, beetles, and bats.

Reduced sympathetic innervation after alteration of target cell neurotransmitter phenotype in transgenic mice.

Neurotransmitters play a variety of important roles during nervous system development. In the present study, we hypothesized that neurotransmitter phenotype of both projecting and target cells is an important factor for the final synaptic linkage and its specificity. To test this hypothesis, we used transgenic techniques to convert serotonin/melatonin-producing cells of the pineal gland into cells that also produce dopamine and investigated the innervation of the phenotypically altered target cells. This phenotypic alteration markedly reduced the noradrenergic innervation originating from the superior cervical ganglia. Although the mechanism by which the reduction occurs is presently unknown, quantitative enzyme-linked immunoassay showed the presence of the equivalent amounts of nerve growth factor (NGF) in the control and transgenic pineal glands, suggesting that it occurred in a NGF-independent manner. The results suggest that target neurotransmitter phenotype influences the formation of afferent connections during development.

Primate photopigments and primate color vision.

The past 15 years have brought much progress in our understanding of several basic features of primate color vision. There has been particular success in cataloging the spectral properties of the cone photopigments found in retinas of a number of primate species and in elucidating the relationship between cone opsin genes and their photopigment products. Direct studies of color vision show that there are several modal patterns of color vision among groupings of primates: (i) Old World monkeys, apes, and humans all enjoy trichromatic color vision, although the former two groups do not seem prone to the polymorphic variations in color vision that are characteristic of people; (ii) most species of New World monkeys are highly polymorphic, with individual animals having any of several types of dichromatic or trichromatic color vision; (iii) less is known about color vision in prosimians, but evidence suggests that at least some diurnal species have dichromatic color vision; and (iv) some nocturnal primates may lack color vision completely. In many cases the photopigments and photopigment gene arrangements underlying these patterns have been revealed and, as a result, hints are emerging about the evolution of color vision among the primates.

Sleep electroencephalogram delta-frequency amplitude, night plasma levels of tumor necrosis factor alpha, and human immunodeficiency virus infection.

We tested the hypothesis that increases in tumor necrosis factor alpha (TNF-alpha) induced by human immunodeficiency virus (HIV) are associated with the increases in slow-wave sleep seen in early HIV infection and the decrease with sleep fragmentation seen in advanced HIV infection. Nocturnal sleep disturbances and associated fatigue contribute to the disability of HIV infection. TNF-alpha causes fatigue in clinical use and promotes slow-wave sleep in animal models. With slow progress toward a vaccine and weak effects from current therapies, efforts are directed toward extending productive life of HIV-infected individuals and shortening the duration of disability in terminal illness. We describe previously unrecognized nocturnal cyclic variations in plasma levels of TNF-alpha in all subjects. In 6 of 10 subjects (1 control subject, 3 HIV-seropositive patients with CD4+ cell number > 400 cells per microliters, and 2 HIV-positive patients with CD4+ cell number < 400 cells per microliters), these fluctuations in TNF-alpha were coupled to the known rhythm of electroencephalogram delta amplitude (square root of power) during sleep. This coupling was not present in 3 HIV-positive subjects with CD4+ cell number < 400 cells per microliters and 1 control subject. In 5 HIV subjects with abnormally low CD4+ cell counts ( < 400 cells per microliters), the number of days since seroconversion correlated significantly with low correlation between TNF-alpha and delta amplitude. We conclude that a previously unrecognized normal, physiological coupling exists between TNF-alpha and delta amplitude during sleep and that the lessened likelihood of this coupling in progressive HIV infection may be important in understanding fatigue-related symptoms and disabilities.

Efeito da estimulação purinérgica sobre a produção de melatonina em macrófagos da linhagem RAW 264.7

A melatonina é um hormônio produzido de forma rítmica e no período de escuro pela glândula pineal bem como de forma não rítmica por diversos tecidos e células imunocompetentes. É sintetizada pela acetilação e metilação da serotonina pela ação das enzimas arilalquilamina N-acetiltransferase (AA-NAT) e acetilserotonina -O-metiltransferase (ASMT) que levam à formação de N-acetilserotonina (NAS) e melatonina (MEL), respectivamente. Nos últimos anos temos demonstrado que síntese de melatonina pela pineal pode ser negativamente modulada por mediadores inflamatórios e pelo ATP que atua como co-transmissor juntamente com a noradrenalina liberada no terminal nervoso simpático que a inerva. Perifericamente, contudo, estes mediadores inflamatórios apresentam um efeito contrário induzindo a produção de melatonina em células imunocompetentes. Estas observações levaram à criação da hipótese de um eixo imune-pineal. Esse trabalho teve como objetivo verificar o efeito do ATP sobre produção de melatonina em macrófagos da linhagem RAW 264.7 Os dados desse trabalho mostram que o ATP é capaz de induzir de maneira dose dependente a produção de melatonina em macrófagos através da modulação das enzimas AA-NAT e ASMT. Foi demostrado também que esse efeito é mediado pelo receptor P2X7 e que a melatonina produzida age autocrina e paracrinamente aumentando a fagocitose de particulas de zimosan. Com isso, podemos concluir que o ATP é um ativador endógeno do eixo imune-pineal

Desenvolvimento e validação de métodos bioanalíticos para o monitoramento dos produtos das vias metabólicas do triptofano em linhagem celular de glioma humano

O metabolismo do triptofano (Trp) se dá pela via das quinureninas (QUIN), pela via serotoninérgica (SER) e pela via das aminas traço. A primeira gera QUIN e uma variedade de outros metabólitos secundários. Quando conduzida pela enzima indolamina 2,3 dioxigenase (IDO) contribui para os fenômenos de tolerância e imune escape de células tumorais; e quando conduzida pela triptofano 2,3 dioxigenase (TDO) no fígado, participa na síntese da niacina e NAD. A via SER leva à formação do neurotransmissor serotonina (SER), que pode gerar o hormônio melatonina (MEL), respectivamente e outros metabólitos biologicamente ativos. Outra via menos estudada, a via das aminas traço, produz produtos neuroativos. Dada a abrangência e importância das rotas metabólicas do Trp, nós desenvolvemos e validamos uma metodologia bioanalítica robusta, seletiva e sensível por cromatografia líquida de alta eficiência (HPLC), acoplado espectrometria de massas (MS) para a determinação simultânea do Trp e seus 15 metabólitos. Para tanto, escolhemos para a avaliação das três vias, linhagens de glioma humano. A escolha por este tipo celular deveu-se ao grande interesse de estudos de metabolismo de Trp em células tumorais, no qual células de glioma tem sido modelo. Nos ensaios com as células de glioma acompanhamos os efeitos de um indutor e inibidores da primeira etapa de metabolização do Trp pela via das quinureninas, ou seja, IFN-γ (indutor da IDO), 1-metiltriptofano (1-MT; inibidor competitivo da IDO) e 680C91 (inibidor seletivo da TDO). Pudemos observar o impacto que a indução ou a inibição do primeiro passo teve sobre os metabólitos subsequentes e as diferenças no metabolismo das duas linhagens estudadas, A172 e T98G. A linhagem T98G só tem atividade de IDO, enquanto que a A172 tem tanto atividade IDO quanto TDO. A indução por IFN-γ mostrou que essa citocina não só atua na formação da via QUIN, mas possui um impacto modesto nas demais rotas. Observamos também que a inibição do 1-MT mostrou seu impacto nos metabólitos invdividualmente, do que a simples relação Trp-QUIN. Contudo, nosso resultados nos permitiu mostrar pela primeira vez a descrição completa dessas vias, em especial nessas linhagens celulares, podendo supor estratégias terapêuticas nessas rotas que estão relacionadas a progressão ou não tumoral.

Mosquitos da Caatinga: biodiversidade, aspectos ecológicos e importância epidemiológica da fauna Culicidae do semiárido brasileiro

Em relação à fauna Culicidae, a Caatinga é um dos biomas mais desconhecidos do Brasil. Há carência de registro de ocorrência de culicídeos, bem como de estudos sobre as interações deles com o ambiente silvestre. Assim, o objetivo deste estudo foi investigar biodiversidade e aspectos ecológicos e epidemiológicos da fauna Culicidae em áreas de conservação do bioma Caatinga. Para isso foram consideradas duas unidades de conservação da Caatinga e realizados 19 levantamentos entomológicos mensais e consecutivos. Foram realizadas coletas de formas imaturas de mosquitos em bromélias, ocos de árvore e criadouros de solo, além da coleta de mosquitos adultos de hábitos diurno, crepuscular e noturno. Ao todo, entre mosquitos adultos e imaturos associados a habitats fitotelmatas, foram coletados 11.456 culicídeos distribuídos em 28 espécies, das quais 11 eram desconhecidas para a ciência. A fauna de imaturos coletados em bromélias e ocos de árvore interferiu na composição da fauna de mosquitos adultos e houve variações na abundância e nos padrões de diversidade de acordo com fitofisionomia do ambiente. Temperatura e umidade foram os parâmetros ambientais mais fortemente associados à abundância de culicídeos. Foram registradas novas ocorrências de anofelinos, coletados em criadouros de solo, ampliando a distribuição das espécies para o semiárido brasileiro. Este é um estudo pioneiro acerca da biodiversidade da fauna Culicidae em áreas de conservação da Caatinga que apresenta uma rica e desconhecida fauna de culicídeos, inédita para a ciência.

Aladdin's Magic Lamp: Developing Methods for Calibration and Geolocation Accuracy Assessment of the DMSP OLS

Nighttime satellite imagery from the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) has a unique capability to observe nocturnal light emissions from sources including cities, wild fires, and gas flares. Data from the DMSP OLS is used in a wide range of studies including mapping urban areas, estimating informal economies, and estimating urban populations. Given the extensive and increasing list of applications a repeatable method for assessing geolocation accuracy, performing inter-calibration, and defining the minimum detectable brightness would be beneficial. An array of portable lights was designed and taken to multiple field sites known to have no other light sources. The lights were operated during nighttime overpasses by the DMSP OLS and observed in the imagery. A first estimate of the minimum detectable brightness is presented based on the field experiments conducted. An assessment of the geolocation accuracy was performed by measuring the distance between the GPS measured location of the lights and the observed location in the imagery. A systematic shift was observed and the mean distance was measured at 2.9km. A method for in situ radiance calibration of the DMSP OLS using a ground based light source as an active target is presented. The wattage of light used by the active target strongly correlates with the signal measured by the DMSP OLS. This approach can be used to enhance our ability to make inter-temporal and inter-satellite comparisons of DMSP OLS imagery. Exploring the possibility of establishing a permanent active target for the calibration of nocturnal imaging systems is recommended. The methods used to assess the minimum detectable brightness, assess the geolocation accuracy, and build inter-calibration models lay the ground work for assessing the energy expended on light emitted into the sky at night. An estimate of the total energy consumed to light the night sky globally is presented.

Characterization of a new murine retinal cell line (MU-PH1) with glial, progenitor and photoreceptor characteristics

Unlike fish and amphibians, mammals do not regenerate retinal neurons throughout life. However, neurogenic potential may be conserved in adult mammal retina and it is necessary to identify the factors that regulate retinal progenitor cells (RPC) proliferative capacity to scope their therapeutic potential. Müller cells can be progenitors for retinal neuronal cells and can play an essential role in the restoration of visual function after retinal injury. Some members of the Toll-like receptor (TLR) family, TLR2, TLR3 and TLR4, are related to progenitor cells proliferation. Müller cells are important in retinal regeneration and stable cell lines are useful for the study of retinal stem cell biology. Our purpose was to obtain a Müller-derived cell line with progenitor characteristics and potential interest in regeneration processes. We obtained and characterized a murine Müller-derived cell line (MU-PH1), which proliferates indefinitely in vitro. Our results show that (i) MU-PH1 cells expresses the Müller cell markers Vimentin, S-100, glutamine synthetase and the progenitor and stem cell markers Nestin, Abcg2, Ascl1, α-tubulin and β-III-tubulin, whereas lacks the expression of CRALBP, GFAP, Chx10, Pax6 and Notch1 markers; (ii) MU-PH1 cell line stably express the photoreceptor markers recoverin, transducin, rhodopsin, blue and red/green opsins and also melanopsin; (iii) the presence of opsins was confirmed by the recording of intracellular free calcium levels during light stimulation; (iv) MU-PH1 cell line also expresses the melatonin MT1 and MT2 receptors; (v) MU-PH1 cells express TLR1, 2, 4 and 6 mRNA; (vi) MU-PH1 express TLR2 at cell surface level; (vii) Candida albicans increases TLR2 and TLR6 mRNA expression; (viii) C. albicans or TLR selective agonists (Pam(3)CysSK(4), LPS) did not elicit morphological changes nor TNF-α secretion; (ix) C. albicans and Pam(3)CysSK(4) augmented MU-PH1 neurospheres formation in a statistically significant manner. Our results indicate that MU-PH1 cell line could be of great interest both as a photoreceptor model and in retinal regeneration approaches and that TLR2 may also play a role in retinal cell proliferation.

Physiological and Morphological Similarities between the Octodon Degus Retina and the Human Retina

Octodon degus is a rodent with diurnal crepuscular activity. Here we compare the function and morphology of the retina of this diurnal rodent with the retinas of nocturnal rodents and humans.