Thermodynamic pathway for the formation of SnSe and SnSe2 polycrystalline thin films by selenization of metal precursors

In this work, tin selenide thin films (SnSex) were grown on soda lime glass substrates by selenization of dc magnetron sputtered Sn metallic precursors. Selenization was performed at maximum temperatures in the range 300 °C to 570 °C. The thickness and the composition of the films were analysed using step profilometry and energy dispersive spectroscopy, respectively. The films were structurally and optically investigated by X-ray diffraction, Raman spectroscopy and optical transmittance and reflectance measurements. X-Ray diffraction patterns suggest that for temperatures between 300 °C and 470 °C, the films are composed of the hexagonal-SnSe2 phase. By increasing the temperature, the films selenized at maximum temperatures of 530 °C and 570 °C show orthorhombic-SnSe as the dominant phase with a preferential crystal orientation along the (400) crystallographic plane. Raman scattering analysis allowed the assignment of peaks at 119 cm−1 and 185 cm−1 to the hexagonal-SnSe2 phase and those at 108 cm−1, 130 cm−1 and 150 cm−1 to the orthorhombic-SnSe phase. All samples presented traces of condensed amorphous Se with a characteristic Raman peak located at 255 cm−1. From optical measurements, the estimated band gap energies for hexagonal-SnSe2 were close to 0.9 eV and 1.7 eV for indirect forbidden and direct transitions, respectively. The samples with the dominant orthorhombic-SnSe phase presented estimated band gap energies of 0.95 eV and 1.15 eV for indirect allowed and direct allowed transitions, respectively.

A checklist for patient safety rounds at the care pathway level

Objective - To define a checklist that can be used to assess the performance of a department and evaluate the implementation of quality management (QM) activities across departments or pathways in acute care hospitals. Design - We developed and tested a checklist for the assessment of QM activities at department level in a cross-sectional study using on-site visits by trained external auditors. Setting and Participants - A sample of 292 hospital departments of 74 acute care hospitals across seven European countries. In every hospital, four departments for the conditions: acute myocardial infarction (AMI), stroke, hip fracture and deliveries participated. Main outcome measures - Four measures of QM activities were evaluated at care pathway level focusing on specialized expertise and responsibility (SER), evidence-based organization of pathways (EBOP), patient safety strategies and clinical review (CR). Results - Participating departments attained mean values on the various scales between 1.2 and 3.7. The theoretical range was 0-4. Three of the four QM measures are identical for the four conditions, whereas one scale (EBOP) has condition-specific items. Correlations showed that every factor was related, but also distinct, and added to the overall picture of QM at pathway level. Conclusion - The newly developed checklist can be used across various types of departments and pathways in acute care hospitals like AMI, deliveries, stroke and hip fracture. The anticipated users of the checklist are internal (e.g. peers within the hospital and hospital executive board) and external auditors (e.g. healthcare inspectorate, professional or patient organizations).

USE OF MUELLER-HINTON BROTH AND AGAR IN THE GERM TUBE TEST

Candida albicans is often isolated from clinical samples, thus its presumptive differentiation from other species of the same genus can be based on its ability to form the germ tube in human serum. Nevertheless, there are two other species that share this characteristic: C. dubliniensis and C. africana. The aim of this study was to compare four different substrates to perform the germ tube (GT) test. The Candida spp. isolates were identified using a manual system (135 C. albicans, 24 C. tropicalis and one C. dubliniensis). The germ tube test was performed with fresh, previously frozen serum and Mueller-Hinton (MH) broth and agar. GT was observed in 96% (130/136) of the isolates through the fresh serum technique, 94% (128/136) through previously frozen serum, 92% (125/136) in MH agar, and 90% (122/136) in MH broth. The sensitivity of each test was higher than 90%, with 100% specificity. Both the MH agar and broth were able to identify the true positives, and false positives were not found. However, some C. albicans isolates were not identified. MH agar and broth may be used in laboratory for the rapid presumptive identification of C. albicans, as an alternative method for germ tube test.

Analysis of the pathway of developing a national mental health plan for Suriname

ABSTRACT: The aim of this analysis was to analyze and describe the steps that have been taken in the development of the mental health policy in Suriname after the WHO AIMS. The objectives are: 1.To review the steps to be taken in developing a mental health policy and plan for a country 2.To gather information and data concerning mental health policy and plan development in Suriname 3.To draw conclusion from the experience gained that can be applied to other countries. In general, the information that was gathered from the four countries Guyana, Barbados, Trinidad & Tobago and Suriname, was compared with the WHO steps for developing a mental health policy and plan. Were these steps taken into consideration, when developing their mental health policy and plan? If not, what were the reasons why it did not happen? The checklist for evaluating a mental health plan was used in Suriname. This checklist assisted to see if the results of the recommendations given by the WHO AIMS to develop a effective and balanced mental health plan were taken into consideration. The mayor findings of the analysis are that Suriname as well as Guyana used the steps in developing their mental health policy and plan. Barbados and Trinidad & Tobago did not develop a mental health policy and plan. Suriname and Guyana have a mental health coordinating body at the Ministry of Health. Trinidad & Tobago as well as Barbados have a mental health focal person at the Ministry of Health of the respective countries. It can be concluded that successfully improving of health systems and services for mental health is combining theoretical concepts, expert knowledge and cooperation of many stakeholders. The appointment of a mental health coordinating unit at the Ministry of Health is crucial for the development of mental health in a country. Furthermore, mental health is everyone’s business and responsibility. Implementing the steps to be taken when developing a mental health policy and plan as recommended by WHO may be a slow process requiring the mobilization of political will. That’s why it is crucial that persons responsible for this process work close with all stakeholders in relevant sectors, taking their needs into consideration and try to translate that in clear objectives. It is common knowledge that improving the quality of mental health must be accompanied by the availability of financial and human resources. Finally, a mental health policy and plan should be one document tackling all aspects of mental health of a community.

New spectroscopic and electrochemical insights on a class I superoxide reductase: evidence for an intramolecular electron-transfer pathway

Biochem. J. (2011) 438,485–494 doi:10.1042/BJ20110836

O2/CO2-sensitive cyclic AMP-signalling pathway in peripheral chemoreceptors

RESUMO: O corpo carotídeo (CB) é um pequeno órgão sensível a variações na PaO2, PaCO2 e pH. As células tipo I (células glómicas) do corpo carotídeo, as unidades sensoriais deste órgão, libertam neurotransmissores em resposta às variações dos gases arteriais. Estes neurotransmissores atuam quer em recetores pré-sinápticos, localizados nas células tipo I, quer em recetores póssinápticos, localizados nas terminações do nervo do seio carotídeo, ou em ambos. A activação dos recetores pré-sinápticos modula a atividade do corpo carotídeo, enquanto que, a activação dos recetores pós-sinápticos, de carater excitatório, desencadeia um aumento da frequência de descarga das fibras do CSN, com subsequente despolarização dos neurónios do gânglio petroso, e posterior despolarização de um grupo específico de neurónios do centro respiratório central, desencadeando, como resposta final, hiperventilação. Estes recetores pré- e pós-sinápticos podem ser classificados em ionotrópicos ou metabotrópicos, estando os últimos acoplados a adenilatos ciclases transmembranares (tmAC). O mecanismo exato pelo qual as variações dos gases arteriais são detetadas pelo CB não se encontra ainda completamente elucidado, mas tem sido sugerido que alterações nos níveis de cAMP estejam associadas ao mecanismo de deteção de variações de O2 e CO2. Os níveis de cAMP podem ser regulados através da sua via de síntese, mediada por dois tipos de adenilatos ciclases: tmAC sensível aos eurotransmissores e adenilato ciclase solúvel (sAC)sensível a variações de HCO3/CO2, e pela sua via de degradação mediada por fosfodiesterases. A via de degradação do cAMP pode ser manipulada farmacologicamente, funcionando enquanto alvo terapêutico para o tratamento de patologias do foro respiratório (e.g. asma, hipertensão pulmonar, doença pulmonar obstructiva crónica e apneia do sono), que induzem um aumento da actividade do CB.O trabalho descrito nesta dissertação partiu da hipótese de que a actividade do CB é manipulada por fármacos, que interferem com a via de sinalização do cAMP, tendo sido nosso objectivo geral, investigar o papel do cAMP na quimiotransdução do CB de rato, e determinar se a actividade dos enzimas responsáveis pela via de sinalização do cAMP é ou não regulada por variações de O2/CO2. Assim, a relevância deste trabalho é a de estudar e identificar possíveis alvos moleculares (sAC, isoformas de tmAC e PDE) com potencial para serem usados no tratamento de patologias relacionadas com o controlo respiratório. A primeira parte do presente trabalho, centrou-se na caracterização farmacológica da PDE4 no CB e em tecidos não quimiorecetores (e.g. gânglio cervical superior e artérias carótidas), e na observação do efeito de hipóxia aguda na acumulação dos níveis de cAMP, induzidos pelos inibidores de PDE, nestes tecidos. A quantificação de cAMP foi efectuada por técnica imunoenzimática (EIA), tendo sido elaboradas curvas de dose-resposta para os efeitos de inibidores, não específicos (IBMX) e específicos para a PDE2 e PDE4 (EHNA, Rolipram e Ro 20-1724), nos níveis de cAMP acumulados, em situações de normóxia (20%O2/5%CO2) e hipóxia (5%O2/5%CO2). A caracterização das PDE no gânglio cervical superior foi aprofundada, utilizando-se a técnica de transferência de energia de ressonância por fluorescência (FRET) em culturas primárias de neurónios, na presença de inibidores não específicos (IBMX) e específicos para a PDE3 e PDE4 (milrinone e rolipram, respetivamente). Foram igualmente estudadas, através de RT-qPCR, as alterações na expressão de PDE3A-B e PDE4A-D, no gânglio cervical superior, em resposta a diferentes percentagens de oxigénio. Na segunda parte do trabalho investigou-se a via de síntese do cAMP no CB em resposta a variações na concentração de HCO3/CO2. Em concreto, o protocolo experimental centrou-se na caracterização da sAC, dado que a sua actividade é regulada por variações de HCO3/CO2. A caracterização da expressão e regulação da sAC, em resposta a variações de HCO3/CO2 ,foi efectuada no CB e em tecidos não quimioreceptores periféricos (e.g. gânglio cervical superior, petroso e nodoso) por qRT-PCR. A actividade deste enzima foi caracterizada indirectamente através da quantificação dos níveis de cAMP (quantificação por EIA), induzidos por diferentes concentrações de HCO3/CO2, na presença de MDL-12,33-A, um inibidore da tmAC. A expressão das isoformas da tmAC no CB e gânglio petroso foi determinada por RT-qPCR. Adicionalmente, estudámos a contribuição relativa da tmAC e sAC no mecanismo de sensibilidade ao CO2 no CB. Para o efeito foram estudadas as alterações: 1) nos níveis de cAMP (quantificado por EIA) na presença de diferentes concentrações de HCO3/CO2 e ao longo do tempo (5-30 min); 2) na ativação da proteína cinase A (PKA, FRET baseado em sensores) em células tipo I do CB; e 3) na frequência de descarga do CSN (registos) na presença e ausência de ativadores e inibidores da sAC,tmAC e PKA. Por último, foi caracterizada a expressão e actividade da sAC nos quimioreceptors centrais (locus ceruleus, rafe e medula ventro-lateral) através de técnicas de RT-qPCR e EIA. A expressão das isoformas da tmAC foi aprofundada no locus coeruleus através de RT-qPCR. Por fim, comparámos a contribuição da tmAC e sAC nos níveis de cAMP no locus coeruleus em condições de normocapnia e hipercapnia.O nosso trabalho teve os seguintes resultados principais: 1) PDE4 está funcional no corpo carotídeo, artérias carótidas e gânglio cervical superior de rato, embora a PDE2 só se encontre funcional neste último; 2) Os efeitos dos inibidores de PDE nos níveis de acumulação de cAMP foram exacerbados em situações de hipóxia aguda no CB e artérias carótidas, mas foram atenuados no gânglio cervical superior; 3) No gânglio cervical superior, diferentes tipos de células apresentaram uma caracterização específica de PDEs, sugerindo uma subpopulação de células neste gânglio com funções fisiológicas distintas; 4) Embora todas as isoformas de PDE4 e PDE3 estivessem presentes no gânglio, a PDE3a, PDE4b e a PDE4d foram as isoformas mais expressas. Por outro lado, incubações de gânglio cervical superior, em diferentes percentagens de oxigénio, não alteraram (não regularam) significativamente a expressão das diferentes isoformas de PDE neste órgão; 5) a sAC encontra-se expressa e funcional no CB e nos quimiorecetores centrais estudados (locus coeruleus, rafe e medula ventrolateral). A sAC apresenta maior expressão no CB comparativamente aos restantes orgãos estudados, exceptuando os testículos, orgão controlo. Variações de HCO3/CO2 de 0/0 para 24/5 aumentaram os níveis de cAMP no CB e quimiorecetores centrais, tendo sido o aumento mais significativo observado no CB. Concentrações acima dos 24mM HCO3/5%CO2 não induziram alterações nos níveis de cAMP, sugerindo que a actividade da sAC se encontra saturada em condições fisiológicas (normocapnia) e que este enzima não desempenha qualquer papel na deteção de situações de hipercapnia; 6) No CB, a expressão das isoformas tmAC1, tmAC4, tmAC6 e tmAC9 é mais elevada comparativamente à expressão da sAC; 7) Utilizamos diferentes inibidores da tmAC (MDL 12-330A, 500μM, 2’5’-ddADO, 30-300μM, SQ 22536, 200μM) e da sAC (KH7, 10-100μM) para estudar a contribuição relativa destes enzimas na acumulação do cAMP no CB. Tanto a tmAC como a sAC contribuem para a acumulação dos níveis de cAMP em condições de hipercapnia. Contudo, existe um maior efeito destes inibidores nas condições de 12 mM HCO3/2.5%CO2 do que em condições de normocapnia e hipercapnia, sugerindo um papel relevante destes enzimas na atividade do CB em situações de hipocapnia; 8) Não se observaram variações nos níveis de cAMP em resposta a diferentes concentrações de HCO3/CO2 ao longo do tempo (5-30 min). O efeito inibitório induzido por ddADO e KH7 foi sobreponível após 5 ou 30 minutos de incubação em todas as concentrações de HCO3/CO2 estudadas; 9) Por último, verificou-se um aumento na frequência da descarga do nervo do seio carotídeo entre as condições de normocapnia e hipercapnia acídica. Ao contrário do KH7 (10μM), o 2’5’-ddADO reduziu significativamente a frequência de descarga do nervo, quer em condições de normocapnia quer de hipercapnia acídica. Contudo, não se verificou aumento na frequência de descarga do nervo entre normocapnia e hipercapnia isohídrica, sugerindo que a sensibilidade à hipercapnia no CB é mediada por variações de pH. Em conclusão, os resultados decorrentes deste trabalho permitiram demonstrar que, embora os enzimas que medeiam a via de sinalização do cAMP possam ser bons alvos terapêuticos em condições particulares, a sua actividade não é específica para o CB. Os resultados sugerem ainda que o cAMP não é um mediador específico da transdução à hipercapnia neste orgão. Contudo, os nossos resultados demonstraram que os níveis de cAMP são mais elevados em condições fisiológicas, o que sugere que o cAMP possa ter uma função homeostática neste orgão. Por último, o presente trabalho demonstrou que os aumentos de cAMP descritos por outros em condições de hipercapnia, não são observáveis quando o pH se encontra controlado. ------------------ ABSTRACT: The work presented in this dissertation was aimed to establish how specific is cAMP-signaling pathways in the CB mainly in different CO2 conditions and how O2 concentrations alter/drives the manipulation of cAMP signaling in the CB. The experimental studies included in this thesis sought to investigate the role of cAMP in the rat CB chemotransduction mechanisms and to determine whether the enzymes that participate in cAMP signal transduction in the CB are regulated by O2/CO2. We characterized the enzymes involved in the cAMP-signaling pathway in the CB (sAC, tmAC, PDE) under different O2/CO2 conditions. Our results demonstrated that many of these enzymes are involved in CO2/O2 sensing and while they may be useful in treating conditions with alterations in CO2/O2 sensing,they will not be specific to chemoreception within the CB: 1) PDE4 is ubiquitously expressed in CB and non-chemoreceptor related tissues and their affinity to inhibitors change with O2 tensions in both CB and carotid arteries, and 2) sAC and tmAC are expressed in peripheral and central chemo- and non-chemoreceptor tissues and their effect on cAMP levels do not change between normocapnic and isohydric hypercapnic conditions. Our results provide evidence against a specific role of cAMP as a mediator for O2 and CO2 chemotransduction in the rat CB and emphasized the role of pH in CO2 sensitivity of the CB. Furthermore, our results demonstrate that cAMP levels are maintained higher under physiological conditions, supporting recent finding from our lab, which all together suggests that cAMP has a homeostatic function in this organ.

A systems biology framework for pathway level culture media engineering: pplication to Pichia pastoris cultures

Dissertação para obtenção do Grau de Doutor em Engenharia Química e Bioquímica

Gene Expression Profiling and Association Studies Implicate the Neuregulin Signaling Pathway in Behçet's Disease Susceptibility

Behçet's disease (BD) is a complex disease with genetic and environmental risk factors implicated in its etiology; however, its pathophysiology is poorly understood. To decipher BD's genetic underpinnings, we combined gene expression profiling with pathway analysis and association studies. We compared the gene expression profiles in peripheral blood mononuclear cells (PBMCs) of 15 patients and 14 matched controls using Affymetrix microarrays and found that the neuregulin signaling pathway was over-represented among the differentially expressed genes. The Epiregulin (EREG), Amphiregulin (AREG), and Neuregulin-1 (NRG1) genes of this pathway stand out as they are also among the top differentially expressed genes. Twelve haplotype tagging SNPs at the EREG-AREG locus and 15 SNPs in NRG1 found associated in at least one published BD genome-wide association study were tested for association with BD in a dataset of 976 Iranian patients and 839 controls. We found a novel association with BD for the rs6845297 SNP located downstream of EREG, and replicated three associations at NRG1 (rs4489285, rs383632, and rs1462891). Multifactor dimensionality reduction analysis indicated the existence of epistatic interactions between EREG and NRG1 variants. EREG-AREG and NRG1, which are members of the epidermal growth factor (EGF) family, seem to modulate BD susceptibility through main effects and gene–gene interactions. These association findings support a role for the EGF/ErbB signaling pathway inBD pathogenesis that warrants further investigation and highlight the importance of combining genetic and genomic approaches to dissect the genetic architecture of complex diseases.

Transthyretin Amyloidosis: Chaperone Concentration Changes and Increased Proteolysis in the Pathway to Disease

Transthyretin amyloidosis is a conformational pathology characterized by the extracellular formation of amyloid deposits and the progressive impairment of the peripheral nervous system. Point mutations in this tetrameric plasma protein decrease its stability and are linked to disease onset and progression. Since non-mutated transthyretin also forms amyloid in systemic senile amyloidosis and some mutation bearers are asymptomatic throughout their lives, non-genetic factors must also be involved in transthyretin amyloidosis. We discovered, using a differential proteomics approach, that extracellular chaperones such as fibrinogen, clusterin, haptoglobin, alpha-1-anti-trypsin and 2-macroglobulin are overrepresented in transthyretin amyloidosis. Our data shows that a complex network of extracellular chaperones are over represented in human plasma and we speculate that they act synergistically to cope with amyloid prone proteins. Proteostasis may thus be as important as point mutations in transthyretin amyloidosis.

Adult B-Cell Acute Lymphoblastic Leukemia Cells Display Decreased PTEN Activity and Constitutive Hyperactivation of PI3K/Akt Pathway Despite High PTEN Protein Levels

Adult B-cell acute lymphoblastic leukemia remains a major therapeutic challenge, requiring a better characterization of the molecular determinants underlying disease progression and resistance to treatment. Here, using a phospho-flow cytometry approach we show that adult diagnostic B-cell acute lymphoblastic leukemia specimens display PI3K/Akt pathway hyperactivation, irrespective of their BCR-ABL status and despite paradoxically high basal expression of PTEN, the major negative regulator of the pathway. Protein kinase CK2 is known to phosphorylate PTEN thereby driving PTEN protein stabilization and concomitant PTEN functional inactivation. In agreement, we found that adult B-cell acute lymphoblastic leukemia samples show significantly higher CK2 kinase activity and lower PTEN lipid phosphatase activity than healthy controls. Moreover, the clinical-grade CK2 inhibitor CX-4945 (Silmitasertib) reversed PTEN levels in leukemia cells to those observed in healthy controls, and promoted leukemia cell death without significantly affecting normal bone marrow cells. Our studies indicate that CK2-mediated PTEN posttranslational inactivation, associated with PI3K/Akt pathway hyperactivation, are a common event in adult B-cell acute lymphoblastic leukemia and suggest that CK2 inhibition may constitute a valid, novel therapeutic tool in this malignancy.

Determination of germ tube, phospholipase, and proteinase production by bloodstream isolates of Candida albicans

Introduction Candida albicans is a commensal and opportunistic agent that causes infection in immunocompromised individuals. Several attributes contribute to the virulence and pathogenicity of this yeast, including the production of germ tubes (GTs) and extracellular hydrolytic enzymes, particularly phospholipase and proteinase. This study aimed to investigate GT production and phospholipase and proteinase activities in bloodstream isolates of C. albicans. Methods One hundred fifty-three C. albicans isolates were obtained from blood samples and analyzed for GT, phospholipase, and proteinase production. The assays were performed in duplicate in egg yolk medium containing bovine serum albumin and human serum. Results Detectable amounts of proteinase were produced by 97% of the isolates, and 78% of the isolates produced phospholipase. GTs were produced by 95% of the isolates. A majority of the isolates exhibited low levels of phospholipase production and high levels of proteinase production. Conclusions Bloodstream isolates of C. albicans produce virulence factors such as GT and hydrolytic enzymes that enable them to cause infection under favorable conditions.

An optimized one-tube, semi-nested PCR assay for Paracoccidioides brasiliensis detection

Introduction Herein, we report a one-tube, semi-nested-polymerase chain reaction (OTsn-PCR) assay for the detection of Paracoccidioides brasiliensis. Methods We developed the OTsn-PCR assay for the detection of P. brasiliensis in clinical specimens and compared it with other PCR methods. Results The OTsn-PCR assay was positive for all clinical samples, and the detection limit was better or equivalent to the other nested or semi-nested PCR methods for P. brasiliensis detection. Conclusions The OTsn-PCR assay described in this paper has a detection limit similar to other reactions for the molecular detection of P. brasiliensis, but this approach is faster and less prone to contamination than other conventional nested or semi-nested PCR assays.

Effects of Rosmarinus officinalis essential oil on germ tube formation by Candida albicans isolated from denture wearers

Introduction The aim of this study was to investigate the effects of Rosmarinus officinalis essential oil on germ tube formation by Candida albicans isolated from denture wearers. Methods Ten C. albicans isolates recovered from denture wearers were tested using 10% fetal bovine serum with or without 4% R. officinalis essential oil. Results The essential oil from R. officinalis completely inhibited germ tube formation in the investigated C. albicans isolates. Conclusions The results demonstrate that the essential oil of R. officinalis modulates C. albicans pathogenicity through its primary virulence factor (i.e., germ tube formation was suppressed).