A reconfigurable arbitrary waveform generator using PWM modulation for ultrasound research

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Background: In ultrasound imaging systems, the digital transmit beamformer is a critical module that generates accurate control over several transmission parameters. However, such transmit front-end module is not typically accessible to ultrasound researchers. To overcome this difficulty, we have been developing a compact and fully programmable digital transmit system using the pulse-width modulation (PWM) technique for generating simultaneous arbitrary waveforms, specifically designed for research purposes. Methods: In this paper we present a reconfigurable arbitrary waveform generator (RAWG) for ultrasound research applications that exploits a high frequency PWM scheme implemented in a low-cost FPGA, taking advantage of its flexibility and parallel processing capability for independent controlling of multiple transmission parameters. The 8-channel platform consists of a FPGA-based development board including an USB 2.0 interface and an arbitrary waveform generator board with eight MD2130 beamformer source drivers for individual control of waveform, amplitude apodization, phase angle and time delay trigger. Results: To evaluate the efficiency of our system, we used equivalent RC loads (1 k Omega and 220 pF) to produce arbitrary excitation waveforms with the Gaussian and Tukey profiles. The PWM carrier frequency was set at 160 MHz featuring high resolution while keeping a minimum time delay of 3.125 ns between pulses to enable the acoustic beam to be focused and/or steered electronically. Preliminary experimental results show that the RAWG can produce complex arbitrary pulses with amplitude over 100 Vpp and central frequency up to 20 MHz with satisfactory linearity of the amplitude apodization, as well as focusing phase adjustment capability with angular resolution of 7.5 degrees. Conclusions: The initial results of this study showed that the proposed research system is suitable for generating simultaneous arbitrary waveforms, providing extensive user control with direct digital access to the various transmission parameters needed to explore alternative ultrasound transmission techniques.12Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FINEPFundacao AraucariaMinistry of HealthConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Effect of esophagogastric devascularization with splenectomy on schistossomal portal hypertension patients' immunity Efeito da cirurgia de desconexão ázigo-portal com esplenectomia na imunidade de doentes com hipertensão portal esquistossomótica

BACKGROUND: Surgical treatment of hemorrhagic complication in schistosomal portal hypertension in our hospital is an esophagogastric devascularization procedure with splenectomy. Infectious risks and immunological alterations imputed to splenectomy may have significant importance. To minimize the consequences of spleen absence, the use of subtotal splenectomy and spleen auto-transplantation were stimulated. AIM: To verify the immunologic alterations imposed by this procedure in our patients. METHOD: Twenty-eight patients with schistosomal portal hypertension and previous history of upper digestive bleeding due to esophagogastric varices rupture underwent elective esophagogastric devascularization and splenectomy. They were prospectively studied before esophagogastric devascularization procedure with splenectomy, 15 and 30 days, 3 and 6 months after the procedure. T and B-lymphocytes, CD4 and CD8 subpopulations were determinated by monoclonal antibodies. Immunoglobulins A, M, G and C3, C4 components of the complement were determinated by radial immunodiffusion. RESULTS: We observed important reduction of all immune cells, increase of IgG and normal levels of IgM, IgA, C3 and C4 at preoperative. CD4/CD8 relation was normal. Six months after esophagogastric devascularization procedure with splenectomy, significant increase in T-lymphocytes, CD4, CD8 and B-lymphocytes were observed. CD4/CD8 relation remained normal. We noted significant increase in C3. IgA, IgM, IgG and C4 had increased, but without significant difference. CONCLUSION: Esophagogastric devascularization procedure with splenectomy determines an increase in T and B-lymphocytes, CD4 and CD8 subpopulations without compromising immunoglobulins and components of complement levels.<br>RACIONAL: A cirurgia de desconexão ázigo-portal com esplenectomia é utilizada no tratamento da complicação hemorrágica varicosa dos esquistossomóticos hepatoesplênicos com hipertensão do sistema portal, no Serviço de Fígado e Hipertensão Portal da Santa Casa de São Paulo. Envolvendo a esplenectomia, os riscos infecciosos e alterações imunológicas imputados a ela têm importância significativa. A esplenectomia subtotal e o auto-implante esplênico foram alternativas descritas para minimizar as conseqüências da esplenectomia nesses doentes. OBJETIVO: Avaliar o estado imunológico dos esquistossomóticos hepatoesplênicos e qual a alteração imunológica imposta pelo procedimento nesses doentes. MÉTODO: Vinte e oito esquistossomóticos com hipertensão portal e episódio hemorrágico varicoso foram estudados prospectivamente antes, 15 e 30 dias e 3 e 6 meses após a desconexão ázigo-portal com esplenectomia. Realizou-se contagem de linfócitos T, B, células CD4+ e CD8+ através de anticorpos monoclonais e dosagem das imunoglobulinas A, M, G e frações C3 e C4 do sistema complemento por imunodifusão radial. RESULTADOS: Obteve-se diminuição importante de todas as células, aumento de IgG e níveis normais de IgM, IgA, C3 e C4 no pré-operatório. A relação CD4+/CD8+ foi normal. Seis meses após a cirurgia, houve aumento significativo do número de linfócitos T, CD4+, CD8+ e linfócitos B. A relação CD4+/CD8+ manteve-se normal, sem variação. Houve aumento significativo nos níveis de C3. IgA, IgM, IgG e C4 também aumentaram, mas sem diferença significativa. CONCLUSÃO: Os linfócitos T, suas subpopulações CD4+ e CD8+, e os linfócitos B estão diminuídos no pré-operatório. Decorridos 6 meses da desconexão ázigo-portal com esplenectomia houve aumento do número de linfócitos T, das subpopulações CD4+ e CD8+, e dos linfócitos B. Após a desconexão ázigo-portal com esplenectomia não houve alteração das dosagens de imunoglobulinas nem diminuição do sistema complemento

Convergent evidences from human and animal studies implicate angiotensin I-converting enzyme activity in cognitive performance in schizophrenia

In schizophrenia (SCZ), higher angiotensin I-converting enzyme (ACE) levels have been reported in patient's blood and cerebrospinal fluid (CSF). Hereby, we propose to explore whether the ACE activity levels are associated to cognitive performance in SCZ. Seventy-two patients with SCZ or schizoaffective disorder diagnosis, and 69 healthy controls (HCs) underwent a cognitive battery with parallel collection of peripheral blood samples to measure ACE activity. Significant higher ACE activity levels were confirmed in the plasma of SCZ patients compared with HCs (Student's t=−5.216; P<0.001). ACE activity significantly correlated to Hopkins delayed recall measures (r=−0.247; P=0.004) and Hopkins total (r=−0.214; P=0.012). Subjects grouped as high ACE activity (above average) had worse performance compared with low ACE activity level group for Hopkins delayed recall measure, even after correction for clinical condition, age, gender and years of education (P=0.029). The adjusted R squared for this final model was 0.343. This result was evident only comparing extreme groups for ACE activity, when splitting the sample in three groups with similar number of subjects. To clarify this finding, we performed an evaluation of the cognitive performance of transgenic mice with three copies of ACE gene in novel object recognition (NOR) test, which showed that such animals presented impairment in NOR (P<0.05) compared with two copies of wild-type animals. The results observed in SCZ patients and animal model suggest both the association of ACE to cognitive deficits in SCZ. This finding may support the evaluation of novel treatment protocols and/or of innovative drugs for specific intervention of cognitive deficits in SCZ envisioning concomitant ACE activity and behavior evaluations

Active galactic nuclei: what’s in a name?

Active Galactic Nuclei (AGN) are energetic astrophysical sources powered by accretion onto supermassive black holes in galaxies, and present unique observational signatures that cover the full electromagnetic spectrum over more than twenty orders of magnitude in frequency. The rich phenomenology of AGN has resulted in a large number of different "flavours" in the literature that now comprise a complex and confusing AGN "zoo". It is increasingly clear that these classifications are only partially related to intrinsic differences between AGN, and primarily reflect variations in a relatively small number of astrophysical parameters as well the method by which each class of AGN is selected. Taken together, observations in different electromagnetic bands as well as variations over time provide complementary windows on the physics of different sub-structures in the AGN. In this review, we present an overview of AGN multi-wavelength properties with the aim of painting their "big picture" through observations in each electromagnetic band from radio to gamma-rays as well as AGN variability. We address what we can learn from each observational method, the impact of selection effects, the physics behind the emission at each wavelength, and the potential for future studies. To conclude we use these observations to piece together the basic architecture of AGN, discuss our current understanding of unification models, and highlight some open questions that present opportunities for future observational and theoretical progress.Comment: Accepted for publication in Astronomy & Astrophysics Review, 56 pages, 25 figure