Footemineite, the Mn-analog of atencioite, from the Foote mine, Kings Mountain, Cleveland County, North Carolina, USA, and its relationship with other roscherite-group minerals

Footemineite, ideally Ca2Mn2+square Mn22+Be4(PO4)(6)(OH)(4)-6H(2)O, triclinic, is a new member of the roscherite group. It occurs on thin fractures crossing quartz-microcline-spodumene pegmatite at the Foote mine, Kings Mountain, Cleveland County, North Carolina, U.S.A. Associated minerals are albite, analcime, eosphorite, siderite/rhodochrosite, fairfieldite, fluorapatite, quartz, milarite, and pyrite. Footemineite forms prismatic to bladed generally rough to barrel-shaped crystals up to about 1.5 mm long and I mm in diameter. Its color is yellow, the streak is white, and the luster is vitreous to slightly pearly. Footemineite is transparent and non-fluorescent. Twinning is simple, by reflection, with twin boundaries across the length of the crystals. Cleavage is good on {0 (1) over bar1}) and {100}. Density (calc.) is 2.873 g/cm(3). Footemineite is biaxial (-), n(alpha) = 1.620(2), n(beta) = 1.627(2), n(gamma) = 1.634(2) (white light). 2V(obs) = 80 degrees, 2V(calc) = 89.6 degrees. Orientation: X boolean AND b similar to 12 degrees, Y boolean AND c similar to 15 degrees, Z boolean AND a similar to 15 degrees. Elongation direction is c, dispersion: r > v or r < v, weak. Pleochroism: beta (brownish yellow) > alpha = gamma (yellow). Mossbauer and IR spectra are given. The chemical composition is (EDS mode electron microprobe, Li and Be by ICP-OES, Fe3+:Fe2+ y Mossbauer, H2O by TG data, wt%): Li2O 0.23, BeO 9.54, CaO 9.43, SrO 0.23, BaO 0.24, MgO 0.18, MnO 26.16, FeO 2.77, Fe2O3 0.62, Al2O3 0.14, P2O5 36.58, SiO2 0.42, H2O 13.1, total 99.64. The empirical formula is (Ca1.89Sr0.03Ba0.02)Sigma(1.94)(Mn-0.90(2+)square(0.10))Sigma(1.00)(square 0.78Li0.17Mg0.05) Sigma(1.00)(Mn3.252+Fe0.432+ Fe0.093+Al0.03)Sigma(3.80) Be-4.30(P5.81Si0.08O24)[(OH)3.64(H2O)0.36]Sigma(4.00)center dot 6.00H(2)O . The strongest reflection peaks of the powder diffraction pattern [d, angstrom (1, %) (hkl)] are 9.575 (53) (010), 5.998 (100) (0 (1) over bar1), 4.848 (26) (021), 3.192 (44) (210), 3.003 (14) (0 (2) over bar2), 2.803 (38) ((1) over bar 03), 2.650 (29) ((2) over bar 02), 2.424 (14) (231). Single-crystal unit-cell parameters are a = 6.788(2), b = 9.972(3), c = 10.014(2) A, (x = 73.84(2), beta = 85.34(2), gamma = 87.44(2)degrees,V = 648.74 angstrom(3), Z = 1. The space group is P (1) over bar. Crystal structure was refined to R = 0.0347 with 1273 independent reflections (F > 2(5). Footemineite is dimorphous with roscherite, and isostructural with atencioite. It is identical with the mineral from Foote mine described as ""triclinic roscherite."" The name is for the Foote mine, type locality for this and several other minerals.

Cimento ósseo de fosfato tricálcio : síntese e influência de aditivos na sua injetabilidade

Cimentos ósseos são materiais desenvolvidos há aproximadamente uma década para aplicações biomédicas. Um cimento deste tipo pode ser preparado misturando um sal de fosfato de cálcio com uma solução aquosa para que se forme uma pasta que possa reagir à temperatura corporal dando lugar a um precipitado que contenha hidroxiapatita [Ca10(PO4)6(OH)2]. A similaridade química e morfológica entre este biomaterial e a parte mineral dos tecidos ósseos permite a osteocondução, sendo o cimento substituído por tecido ósseo novo com o tempo e com a vantagem de não desencadear rejeição. Estes cimentos são usados principalmente para as operações de preenchimento ósseo, que requer operações cirúrgicas extremamente invasivas. O desafio atual é colocar este biomaterial no local de enxerto pelo método menos agressivo possível. A inovação consiste em formular composição de cimento ósseo injetável pela incorporação de aditivos. No entanto, propriedades como reduzido tempo de cura, limitada dissolução em meio líquido e resistência mecânica adequada ao local do enxerto devem ser preservadas. Neste estudo, foram abordados oito diferentes aditivos que foram incorporados ao fosfato tricálcico [Ca3(PO4)2] sintetizado, juntamente com a solução do acelerador de cura (2,5%massa de Na2HPO4 dissolvido em água destilada): CMC (carboximetilcelulose), polímero de AGAR (polissacarídeo de algas vermelhas), alginato de sódio, quitosana (fibra natural derivada da quitina), pirofosfato de sódio, lignosulfonato de sódio (polissacarídeo de algas marrons), glicerina e ácido láctico nas concentrações 0,4%; 0,8%; 1,6%; 3,2%; 6,4% em massa. Os resultados demonstraram que foi possível obter composições de cimento de fosfato de cálcio injetáveis para uso biomédico. Constatou-se uma relação de proporcionalidade direta entre a injetabilidade do cimento e tempo de injeção, sendo a injetabilidade dependente do comportamento reológico das pastas. Todas formulações testadas seguiram a mesma tendência de redução da resistência mecânica à compressão e aumento da porosidade com o aumento da quantidade de aditivo incorporado. Verificou-se que as formulações com 1,6% de carboxi-metil-celulose, 1,6% de AGAR e 0,8% de alginato de sódio, permitiram a obtenção de uma viscosidade suficiente para uma boa homogeneização e injeção, apresentando ao final da cura resistência mecânica à compressão semelhante ao do osso esponjoso.

Desenvolvimento de biocerâmicas porosas de hidroxiapatita para utilização como scaffolds para regeneração óssea

Biocerâmicas porosas tem aplicações biomédicas importantes como preenchimento de defeitos ósseos e scaffolds na engenharia de tecidos. A hidroxiapatita (HA, Ca10(PO4)6(OH)2) que apresenta semelhança química e estrutural com a fase mineral dos ossos e dos dentes, é biocompatível e osteocondutiva, e tem excelente afinidade química e biológica com os tecidos ósseos. Este trabalho teve como objetivo desenvolver biocerâmicas porosas HA para utilização como scaffold para regeneração óssea empregando-se a técnica de réplica da esponja polimérica. A pasta biocerâmica de HA foi obtida por via úmida utilizando hidróxido de cálcio [Ca(OH)2] e ácido fosfórico (H3PO4) e impregnada em esponjas de poliuretano com diferentes densidades. Tratamento térmico a 600°C por 1h foi realizado para eliminação da esponja seguido da sinterização a 1100°C por 2 horas. Os scaffolds apresentaram a HA como fase majoritária, elevada porosidade (> 70%) e poros com tamanhos variando na ordem de macro (>100μm) e microporosidade (1-20μm), sendo estes fatores adequados para a aplicação como scaffolds para regeneração óssea.

Síntese de hidroxiapatita pelo método sol-gel utilizando precursores alternativos: nitrato de cálcio e ácido fosfórico

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análise peptidômica dos venenos de vespas sociais neotropicais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Expression and activity of the cytochrome P450 2E1 in patients with nonalcoholic steatosis and steatohepatitis

BACKGROUND/AIMS: Nonalcoholic steatohepatitis (NASH) and nonalcoholic fatty liver (NAFL) have a different prognosis and should be dealt with differently. The pathogenesis of NASH implicates the overexpression of cytochrome P450 2E1 (CYP2E1). We investigated whether the noninvasive determination of CYP2E1 activity could replace a liver biopsy in order to differentiate NASH from NAFL. METHOD: Forty patients referred for suspicion of NASH underwent liver biopsy. In these patients, CYP2E1 activity was determined noninvasively by the 6-hydroxychlorzoxazone/chlorzoxazone (CHZ) ratio (CHZ test). Expression of CYP2E1 on liver slides was assessed by immunohistochemistry, and immunostaining for smooth muscle actin was used to assess the activation of hepatic stellate cells (HSC). RESULTS: Thirty patients with NASH were compared with 10 subjects with NAFL. No statistically significant difference could be identified for the clinical and biochemical parameters between the two groups. In the histology, steatosis was more important in NASH than in NAFL (P<0.0001). There was no difference either in the activity (CHZ test) or in the expression of CYP2E1 (immunohistochemistry) between patients with NASH and patients with NAFL. The degree of HSC activation was also comparable between the two groups. A positive and significant correlation was found between the activity of CYP2E1 and body mass index (P<0.001) as well as with the degree of steatosis (P=0.008). CONCLUSION: For patients suspected to have NASH, noninvasive tests including the determination of the CYP2E1 activity are unable to distinguish them from patients with steatosis.

A Study on the Fluorescent Properties of Nanoapatite Particles Under Externally Applied Magnetic Fields

Hydroxyapatite is a naturally occurring mineral found in human bones and teeth. Its chemical formula is: Ca10(PO4)6(OH)2. In this project hydroxyapatite nanoparticles were doped with iron or europium to give the particles magnetic or fluorescent properties, respectively. The magnetic and fluorescent responses of these particles under externally applied magnetic fields has not yet been fully characterized.

Proteomic characterization of the FUS/TLS interactome

FUS/TLS (fused in sarcoma/translocated in liposarcoma) is a ubiquitously expressed RNA-binding protein, that has been discovered as fused to transcription factors in several human sarcomas and found in protein aggregates in neurons of patients with an inherited form of Amyotrophic Lateral Sclerosis [1]. To date, FUS has been implicated in a variety of cellular processes such as gene expression control, transcriptional regulation, pre-mRNA splicing and miRNA processing [2]. In addition, some evidences link FUS to genome stability control and DNA damage response. In fact, mice lacking FUS are hypersensitive to ionizing radiation and show high levels of chromosome instability and in response to double-strand breaks, FUS gets phosphorylated by the protein kinase ATM [3, 4, 5]. Moreover, upon DNA damage stress, FUS mediates Ebp1 (ErbB3 receptor-binding protein) SUMOylation, a post-translational modification that is required for its onco-suppressive activity, by acting as SUMO E3 ligase [6]. The study aims to investigate the role of FUS in DNA damage response and SUMOylation, two cellular pathways tightly interconnected to each other. Moreover, we will exploit biochemical and mass spectrometry-based approaches in order to identify other potential substrates of the E3 SUMO ligase activity of FUS. Preliminary results of mass spectrometric identification of FUS interacting proteins, in HEK293 and SHSY5Y cells, highlighted the interaction of FUS with several proteins involved in DNA damage response and many of those have been described already as target of SUMOylation, such as XRCC5, DDX5, PARP1, Nucleophosmin, and others. These evidences strengthen the hypothesis that FUS might represent a link between these pathways, even thou its exact role still needs to be clearly addressed. [1] Vance C. et al. (2009) Science 323(5918): p. 1208-11 [2] Fiesel FC., Kahle PJ. (2011) FEBS J. 278(19): p. 3550-68 [3] Kuroda M. et al. (2000) Embo J. 19(3): p. 453-62 [4] Hicks GG. et al. (2000) Nat Genet. 24(2):p. 175-9 [5] Gardiner M. et al. (2008) Biochem J. 415(2): p. 297-307 [6] Oh SM. et al. (2010) Oncogene 29(7): p. 1017-30

Chlorophyll Breakdown in Tobacco: On the Structure of Two Nonfluorescent Chlorophyll Catabolites

In extracts of senescent leaves of the tobacco plant Nicotiana rustica, two colorless compounds with UV/VIS characteristics of nonfluorescent chlorophyll catabolites (NCCs) were detected and tentatively identified as Nr-NCCs. These two polar NCCs were found in similar amounts in the fresh extracts, and their constitutions could be determined by spectroscopic analysis. The data showed both of the two Nr-NCCs to have the same tetrapyrrolic core structure, as reported previously for all other NCCs from senescent higher plants. In the less polar catabolite, named Nr-NCC-2, this core structure was conjugated with a glucopyranose unit, as similarly discovered earlier in Bn-NCC-2, an NCC from oilseed rape (Brassica napus). The more polar NCC from tobacco leaves, Nr-NCC-1, carried an additional malonyl substituent at the 6′-OH group of the glucopyranosyl moiety. Partial (enzyme-catalyzed) hydrolysis of Nr-NCC-1 gave Nr-NCC-2, while enzyme-catalyzed malonylation of Nr-NCC-2 gave Nr-NCC-1, establishing the identity of their basic tetrapyrrole structure. In earlier work (on the polar NCCs from oilseed rape), only separate glucopyranosyl and malonyl functionalities were detected. Nr-NCC-1, thus, represents a further variant of the structures of NCCs from senescent higher plants and exhibits an unprecedented peripheral refunctionalization in chlorophyll catabolites.

Desenvolvimento de hidroxiapatita contendo prata via precipitação e imersão: avaliação do efeito antimicrobiano

A utilização de substitutos ósseos para recuperação da função perdida é uma constante busca dentro da área médica. Por isso os biomateriais têm recebido uma atenção muito grande por parte da comunidade científica, dentre eles os materiais a base de fosfato de cálcio. A hidroxiapatita, Ca10 (PO4)6 (OH) 2, tem sido muito estudada, pois além de representar a constituição da massa dos ossos naturais e dentes em 30 a 70%, possui propriedades de bioatividade e osteocondutividade, favorecendo e auxiliando o crescimento do tecido ósseo. Em contrapartida, infecções bacterianas podem surgir após o implante ocasionando a perda da funcionalidade a curto e médio prazo. Várias alternativas estão sendo testadas, geralmente associadas ao uso de antibióticos convencionais incorporados aos biomateriais. Uma alternativa a tais antibióticos seria a utilização de metais que possuem propriedades antibacterianas. A prata (Ag) é conhecida como um metal bactericida e por isso ganhou lugar de destaque dentre os estudos como um aliado importante no controle das infecções pós-cirúrgicas. Este trabalho teve como objetivo sintetizar, caracterizar e avaliar o efeito antimicrobiano da adição de íons de prata em hidroxiapatita. Foram obtidos pós de hidroxiapatita contendo prata (HAAg), nas concentrações de 0,1M; 0,01M e 0,001M pelo método de precipitação em temperatura ambiente e por imersão do pó de hidroxiapatita em soluções aquosas. As fases cristalinas e os grupamentos iônicos foram analisados para cada condição por técnicas de difração de raios X (DRX) e espectroscopia no infravermelho (IV) respectivamente. As informações sobre a morfologia e identificação de elementos químicos foi realizado pela técnica de microscopia eletrônica de varredura com espectroscopia de energia dispersiva (MEV EDS). As avaliações antimicrobianas foram realizadas por ensaios qualitativos e quantitativos, o ensaio qualitativo utilizou o teste de halo de difusão em disco para Staphylococcus aureus e Escherichia coli e o ensaio quantitativo utilizou contagem de bactérias para as cepas de Staphylococcus aureus. Os resultados de DRX e IV indicaram que independentemente do método de obtenção da HAAg foi possível observar a presença de prata metálica caracterizada pelos picos em 2θ=38,1º e 44,3º nas amostras HAAg0,1Im, HAAg0,1Pr e HAAg0,01Pr. Observou-se também a presença de AgO, correspondente ao pico em 2θ=37,5º nas amostras de HAAg0,01Pr e HAAg0,001Pr. Nos espectros de IV estão presentes as bandas que caracterizam a fase HA, referentes aos grupamentos PO43-, OH- e CO32-. Analisados em conjunto os ensaios qualitativos e quantitativos, as amostras HAAg0,01Im e HAAg0,001Im sintetizadas por imersão indicaram os melhores resultados para o ensaio de disco difusão, por apresentarem formação de halo inibição do crescimento bacteriano para a bactéria S. aureus. Para os ensaios quantitativos as amostras obtidas por precipitação com concentrações 0,1M e 0,01M de prata apresentaram melhor resultado por inibirem o crescimento bacteriano para as cepas S. aureus.

In-vitro study of the spontaneous calcification of PHEMA-based hydrogels in simulated body fluid

In-vitro calcification of poly(2-hydroxyethyl methacrylate) (PHEMA)-based hydrogels in simulated body fluid (SBF) under a steady/batch system without agitation or stirring the solutions has been investigated. It was noted that the formation of calcium phosphate (CaP) deposits primarily proceeded through spontaneous precipitation. The CaP deposits were found both on the surface and inside the hydrogels. It appears that the effect of chemical structure or reducing the relative number of oxygen atoms in the copolymers on the degree of calcification was only important at the early stage of calcification. The morphology of the CaP deposits was observed to be spherical aggregates with a thickness of the CaP layer less than 0.5 mu m. Additionally, the CaP deposits were found to be poorly crystalline or to have nano-size crystals, or to exist mostly as an amorphous phase. Characterization of the CaP phases in the deposits revealed that the deposits were comprised mainly of whitlockite [Ca9MgH(PO4)(7)] type apatite and DCPD (CaHPO4 center dot 2H(2)O) as the precursors of hydroxyapatite [Ca-10(PO4)(6)(OH)(2)]. The presence of carbonate in the deposits was also detected during the calcification of PHEMA based hydrogels in SBF solution.

Síntese e caracterização estrutural, magnética e térmica da hidroxiapatita dopada com ferro

In this work, composites were prepared using high energy mechanical milling from the precursors hydroxyapatite - HAp (Ca10(PO4)6(OH)2) and metallic iron ( -Fe ). The main goal here is to study composites in order to employ them in magnetic hyperthermia for cancer therapy. The produced samples were characterized by X-ray di raction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), magnetization curves as a function of applied eld (MxH), and nally measurements of magnetic hyperthermia. The XRD patterns of the milled samples HAp/Fe revealed only the presence of precursor materials. The SEM showed clusters with irregular shapes. The magnetization curves indicated typical cases of weak ferromagnetic behavior. For samples submitted to grinding and annealing, the identi ed phases were: HAp (Ca10(PO4)6(OH)2), hematite (Fe2O3) and Calcium Iron Phosphate (Ca9Fe(PO4)7). Analyzing the results of MxH, there was a reduction of the saturation magnetization, given that the Fe was incorporated into HAp. Hysteresis curves obtained at 300 K are characteristics of samples possessing over a phase. At 77 K, the behavior of the hysteresis curve is in uenced by the presence of hematite, which is antiferromagnetic. Already at T = 4.2 K, it is observed a weak ferromagnetic behavior. Furthermore, there is the e ect of exchange bias. Regarding the magnetic hyperthermia, the results of temperature measurements as a function of the alternating eld are promising for applications in magnetic hyperthermia and other biomedical applications.

The Effects of Brominated Flame Retardants on Thyroid Hormone Homeostasis in Human Placenta Tissues and Cell Culture

Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants (BFRs) that have been heavily used in consumer products such as furniture foams, plastics, and textiles since the mid-1970’s. BFRs are added to products in order to meet state flammability standards intended to increase indoor safety in the event of a fire. The three commercial PBDE mixtures, Penta-, Octa-, and DecaBDE, have all been banned in the United States, however, limited use of DecaBDE is still permitted. PBDEs were phased out of production and added to the Stockholm Convention due to concerns over their environmental persistence and toxicity. Human exposure to PBDEs occurs primarily through the inadvertent ingestion of contaminated house dust, as well as though dietary sources. Despite the phase-out and discontinued use of PBDEs, human exposure to this class of chemicals is likely to continue for decades due to the continued use of treated products and existing environmental reservoirs of PBDEs. Extensive research over the years has shown that PBDEs disrupt thyroid hormone (TH) levels and neurodevelopmental endpoints in rodent and fish models. Additionally, there is growing epidemiological evidence linking PBDE exposure in humans to altered TH homeostasis and neurodevelopmental impairments in children. Due to the importance of THs throughout gestation, there is a great need to understand the effects of BFRs on the developing fetus. Specifically, the placenta plays a critical role in the transport, metabolism, and delivery of THs to the fetal compartment during pregnancy and is a likely target for BFR bioaccumulation and endocrine disruption. The central hypothesis of this dissertation research is that BFRs disrupt the activity of TH sulfotransferase (SULT) enzymes, thereby altering TH concentrations in the placenta.

In the first aim of this dissertation research, the concentrations of PBDEs and 2,4,6-TBP were measured in a cohort of 102 placenta tissue samples from an ongoing pregnancy cohort in Durham, NC. Methods were developed for the extraction and analysis of the BFR analytes. It was found that 2,4,6-TBP was significantly correlated with all PBDE analytes, indicating that 2,4,6-TBP may share common product applications with PBDEs or that 2,4,6-TBP is a metabolite of PBDE compounds. Additionally, this was the first study to measure 2,4,6-TBP in human placenta tissues.

In the second aim of this dissertation research, the placenta tissue concentrations of THs, as well as the endogenous activity of deiodinase (DI) and TH SULT enzymes were quantified using the same cohort of 102 placenta tissue samples. Enzyme activity was detected in all samples and this was the first study to measure TH DI and SULT activity in human placenta tissues. Enzyme activities and TH concentrations were compared with BFR concentrations measured in Aim 1. There were few statistically significant associations observed for the combined data, however, upon stratifying the data set based on infant sex, additional significant associations were observed. For example, among males, those with the highest concentrations of BDE-99 in placenta had T3 levels 0.80 times those with the lowest concentration of BDE-99 (95% confidence interval (CI): 0.59, 1.07). Whereas females with the highest concentrations of BDE-99 in placenta had T3 levels 1.50 times those with the lowest concentration of BDE-99 (95% CI: 1.10, 2.04). Additionally, all BFR analyte concentrations were higher in the placenta of males versus females and they were significantly higher for 2,4,6-TBP and BDE-209. 3,3’-T2 SULT activity was significantly higher in female placenta tissues, while type 3 DI activity was significantly higher in male placenta tissues. This research is the first to show sex-specific differences in the bioaccumulation of BFRs in human placenta tissue, as well as differences in TH concentrations and endogenous DI and SULT activity. The underlying mechanisms of these observed sex differences warrant further investigation.

In the third aim of this dissertation research, the effects of BFRs were examined in a human choriocarcinoma placenta cell line, BeWo. Michaelis-Menten parameters and inhibition curves were calculated for 2,4,6-TBP, 3-OH BDE-47, and 6-OH BDE-47. 2,4,6-TBP was shown to be the most potent inhibitor of 3,3’-T2 SULT activity with a calculated IC50 value of 11.6 nM. It was also shown that 2,4,6-TBP and 3-OH BDE-47 exhibit mixed inhibition of 3,3’-T2 sulfation in BeWo cell homogenates. Next, a series of cell culture exposure experiments were performed using 1, 6, 12, and 24 hour exposure durations. Once again, 2,4,6-TBP was shown to be the most potent inhibitor of basal 3,3’-T2 SULT activity by significantly decreasing activity at the high and medium dose (1 M and 0.5 M, respectively) at all measured time points. Interestingly, BDE-99 was also shown to inhibit basal 3,3’-T2 SULT activity in BeWo cells following the 24 hour exposure, despite exhibiting no inhibitory effects in the BeWo cell homogenate experiments. This indicates that BDE-99 must act through a pathway other than direct enzyme inhibition. Following exposures, the TH concentrations in the cell culture growth media and mRNA expression of TH-related genes were also examined. There was no observed effect of BFR treatment on these endpoints. Future work should focus on determining the downstream biological effects of TH SULT disruption in placental cells, as well as the underlying mechanisms of action responsible for reductions in basal TH SULT activity following BFR exposure.

This was one of the first studies to measure BFRs in a cohort of placenta tissue samples from the United States and the first study to measure THs, DI activity, and SULT activity in human placenta tissues. This research provides a novel contribution to our growing understanding of the effects of BFRs on TH homeostasis within the human placenta, and provides further evidence for sex-specific differences within this important organ. Future research should continue to investigate the effects of environmental contaminants on TH homeostasis within the placenta, as this represents the most critical and vulnerable stage of human development.

Famílias Unipessoais Idosas: um estudo das redes sociais pessoais de idosos que vivem sós

Objetivos: O presente estudo tem como objetivo analisar as características estruturais, funcionais e relacionais-contextuais das redes sociais pessoais de famílias unipessoais idosas. Metodologia: Utilizámos para recolha de dados um questionário para caracterizar sociodemograficamente a amostra, o Instrumento de Análise da Rede Social Pessoal (versão para idosos) (IARSP-Idosos) (Guadalupe, 2010; Guadalupe e Vicente 2012) e a escala de solidão UCLA (Neto, 1989). Participantes: A amostra é constituída por 567 indivíduos com média de idades de 75,53 anos, maioritariamente do sexo feminino (63,0%; n = 357). Predominam os sujeitos casados (53,7%; n = 304), com filhos (87,8%; n = 498) e em situação de coabitação (n = 450; 79,4%). Contudo, 20,6% (n = 117) vivem sós, constituindo as famílias unipessoais. Resultados: As redes sociais dos idosos têm em média 7,99 elementos, predominantemente familiares (M = 76,89%). Os participantes percecionam um nível elevado de apoio por parte das suas redes. São redes coesas, pouco dispersas e os contactos entre os elementos são frequentes. As mulheres, os indivíduos solteiros, viúvos ou divorciados e os idosos sem filhos têm uma maior probabilidade de viverem sós (p < 0,05) e estes apresentam uma maior probabilidade de necessitar de apoio social formal (p < 0,05). As famílias unipessoais, quando comparadas com os que não vivem sós, apresentam um maior número de campos relacionais e maior proporção de relações de amizade e de vizinhança (p < 0,05). Têm menor perceção de apoio material e instrumental, informativo, companhia social, acesso a novos vínculos e reciprocidade de apoio (p < 0,05). Além disso, referem menor frequência de contactos e uma maior dispersão geográfica (p < 0,05). Nas famílias unipessoais, observou-se a existência de correlações negativas significativas (p < 0,05) entre a percepção de solidão e o tamanho da rede, a proporção das relações familiares na rede, o apoio emocional e informativo e a reciprocidade de apoio. CONCLUSÃO: Os idosos com famílias unipessoais percecionam menor apoio por parte das suas redes, tendo uma maior propensão à solidão. É fundamental, ao longo do ciclo vital, promover a quantidade e qualidade dos vínculos, no sentido de manter a efetividade do suporte das redes mesmo quando se vive só. / Objectives: The present study aims to analyze the structural, functional and relational-contextual characteristics of older single-person households. Methodology: We used as instruments a questionnaire to evaluate sociodemographic data, the Instrumento de Análise da Rede Social Pessoal (version for elderly people: IARSP-Idosos) (Guadalupe, 2010; Guadalupe e Vicente 2012) and the UCLA Loneliness Scale (Neto, 1989). Participants: The sample consists of 567 individuals with an average age of 75.53 years, mostly females (63.0%; n = 357). There is a predominance of married individuals (53.7%; n = 304) with children (87.8%; n = 498). Older people live mainly in cohabitation (n = 450; 79.4%), however 20.6% oh them live alone, constituting one-person households. Results: The elderly personal social networks have 8 elements, on average, with a predominance of family relationships (M = 76.89%). The participants perceived a high level of support from their networks. In general the networks are cohesive, with low dispersion and have frequent contacts. The women, single, widowed or divorced and childless elderly are more likely to live alone (p < 0.05) and to need social services support (p < 0.05). The single-person households, compared with those who do not live alone, have a greater number of relational fields and a higher proportion of friendships and neighborhood relations (p < 0.05). They have a lower perception of material and informative support, social company and acess to new ties and reciprocal support (p < 0.05). They also refer lowest frequency of contacts and a wider geographical dispersion (p < 0.05). In single-person households there was a negative significant correlation between the perception of loneliness and the social network size, the proportion of family relationships in the network, emotional and informational support and reciprocal support. Conclusions: The elderly single-person households perceived less support from their networks and a greater propensity to loneliness. It is critical to promot the quality of ties, rather then their quantity, throughout the life cycle, in order to maintain the network effectiveness even when the person lives alone.

Determination of chlorzoxazone and 6-hydroxychlorzoxazone in plasma by gas chromatography--mass spectrometry.

A gas chromatographic-mass spectrometric method is presented which allows the determination of chlorzoxazone and 6-hydroxychlorzoxazone after derivatization with the reagent N-tert.-butyldimethylsilyl-N-methyltrifluoroacetamide. No interference was observed from endogenous compounds following the extraction of plasma samples from six different human subjects. The standard curves were linear over a working range of 20 to 4000 ng/ml and of 20 to 1000 ng/ml for chlorzoxazone and 6-hydroxychlorzoxazone, respectively. Recoveries ranged from 65 to 97% for the two compounds and intra- and inter-day coefficients of variation were always less than 9%. The limit of quantitation of the method was found to be 5 ng/ml for the two compounds, hence allowing its use for single low dose pharmacokinetics.