Immunoglobulins in saliva of preterm and full-term infants. A longitudinal study from 0-18 months of age

The aim of this longitudinal study was to determine salivary levels of total IgA, IgG and IgM in 84 preterm and 214 full-term infants, from birth to 18 months of age. Unstimulated whole saliva was collected from each infant at birth, and subsequently at 3-monthly intervals. Immunoglobulin levels were estimated using an ELISA technique. At birth, IgA was detected in 147/214 (69%) full-term infants but only 47/84 (56%) preterm infants (P

The effect of heat transfer mode on heart rate responses and hysteresis during heating and cooling in the estuarine crocodile Crocodylus porosus

The effect of heating and cooling on heart rate in the estuarine crocodile Crocodylus porosus was studied in response to different heat transfer mechanisms and heat loads. Three heating treatments were investigated. C. porosus were: (1) exposed to a radiant heat source under dry conditions; (2) heated via radiant energy while half-submerged in flowing water at 23degreesC and (3) heated via convective transfer by increasing water temperature from 23degreesC to 35degreesC. Cooling was achieved in all treatments by removing the heat source and with C. porosus half-submerged in flowing water at 23degreesC. In all treatments, the heart rate of C. porosus increased markedly in response to heating and decreased rapidly with the removal of the heat source. Heart rate during heating was significantly faster than during cooling at any given body temperature, i.e. there was a significant heart rate hysteresis. There were two identifiable responses to heating and cooling. During the initial stages of applying or removing the heat source, there was a dramatic increase or decrease in heart rate ('rapid response'), respectively, indicating a possible cardiac reflex. This rapid change in heart rate with only a small change or no change in body temperature (

Modeling diffraction in free-space optical interconnects by the mode expansion method

Free-space optical interconnects (FSOIs), made up of dense arrays of vertical-cavity surface-emitting lasers, photodetectors and microlenses can be used for implementing high-speed and high-density communication links, and hence replace the inferior electrical interconnects. A major concern in the design of FSOIs is minimization of the optical channel cross talk arising from laser beam diffraction. In this article we introduce modifications to the mode expansion method of Tanaka et al. [IEEE Trans. Microwave Theory Tech. MTT-20, 749 (1972)] to make it an efficient tool for modelling and design of FSOIs in the presence of diffraction. We demonstrate that our modified mode expansion method has accuracy similar to the exact solution of the Huygens-Kirchhoff diffraction integral in cases of both weak and strong beam clipping, and that it is much more accurate than the existing approximations. The strength of the method is twofold: first, it is applicable in the region of pronounced diffraction (strong beam clipping) where all other approximations fail and, second, unlike the exact-solution method, it can be efficiently used for modelling diffraction on multiple apertures. These features make the mode expansion method useful for design and optimization of free-space architectures containing multiple optical elements inclusive of optical interconnects and optical clock distribution systems. (C) 2003 Optical Society of America.

A longitudinal analysis of sex differences in bone mineral accrual in healthy 8-19-year-old boys and girls

Background: Although early in life there is little discernible difference in bone mass between boys and girls, at puberty sex differences are observed. It is uncertain if these differences represent differences in bone mass or just differences in anthropometric dimensions. Aim: The study aimed to identify whether sex independently affects bone mineral content (BMC) accrual in growing boys and girls. Three sites are investigated: total body (TB), femoral neck (FN) and lumbar spine (LS). Subjects and methods: 85 boys and 67 girls were assessed annually for seven consecutive years. BMC was assessed by dual energy X-ray absorptiometry (DXA). Biological age was defined as years from age at peak height velocity (PHV). Data were analysed using a hierarchical (random effects) modelling approach. Results: When biological age, body size and body composition were controlled, boys had statistically significantly higher TB and FN BMC at all maturity levels (p < 0.05). No independent sex differences were found at the LS (p > 0.05). Conclusion: Although a statistical significant sex effect is observed, it is less than the error of the measurement, and thus sex difference are debatable. In general, sex difference are explained by anthropometric difference

Aboriginal and Torres Strait Islander health research and the conduct of longitudinal studies: issues for debate

The National Health and Medical Research Council, Research Agenda Working Group (RAWG), and the literature on Indigenous health have identified the need to fill gaps in descriptive data on Aboriginal and Torres Strait Islander health and noted both the lack of research with urban populations and the need for longitudinal studies. This paper presents some of the broad ethical and methodological challenges associated with longitudinal research in Indigenous health and focuses particularly on national studies and studies in urban areas. Our goal is to advance debate in the public health arena about the application of ethical guidelines and the conduct of longitudinal studies in Aboriginal and Torres Strait Islander communities. We encourage others to offer their experiences in this field.

Effects of physical activity on emotional well-being among older Australian women - Cross-sectional and longitudinal analyses

Objective: To explore relationships between physical activity and mental health cross-sectionally and longitudinally in a large cohort of older Australian women. Method: Women in their 70s participating in the Australian Longitudinal Study on Women's Health responded in 1996 (aged 70-75) and in 1999 (aged 73-78). Cross-sectional data were analyzed for 10,063 women and longitudinal data for 6472. Self-reports were used to categorize women into four categories of physical activity at each time point as well as to define four physical activity transition categories across the 3-year period. Outcome variables for the cross-sectional analyses were the mental health component score (MCS) and mental health subscales of the Medical Outcomes Study Short Form (SF-36). The longitudinal analyses focused on changes in these variables. Confounders included the physical health component scale (PCS) of the SF-36, marital status, body mass index (BMI) and life events. Adjustment for baseline scores was included for the longitudinal analyses. Results: Cross-sectionally, higher levels of physical activity were associated with higher scores on all dependent variables, both with and without adjustment for confounders. Longitudinally, the effects were weaker, but women who had made a transition from some physical activity to none generally showed more negative changes in emotional well-being than those who had always been sedentary, while those who maintained or adopted physical activity had better outcomes. Conclusion: Physical activity is associated with emotional well-being among a population cohort of older women both cross-sectionally and longitudinally, supporting the need for the promotion of appropriate physical activity in this age group. (C) 2003 Elsevier Science Inc. All rights reserved.

Relationship of ventricular longitudinal function to contractile reserve in patients with mitral regurgitation

Background Latent left ventricular (LV) dysfunction in patients with valvular or myocardial disease may be identified by loss of contractile reserve (CR) at exercise echocardiography. Contraction in the LV longitudinal axis may be more sensitive than radial contraction to minor disturbances of LV function. We sought to determine whether tissue Doppler measurement of longitudinal function could be used to identify CR. Methods Exercise echocardiography was performed in 86 patients (20 women, age 53 +/- 18 years), 72 with asymptomatic or minimally symptomatic mitral regurgitation, and 14 normal controls. Pulsed-wave tissue Doppler imaging (DTI) was used to measure maximum annular systolic velocity at rest and stress. Inducible ischemia was excluded by analysis of wall motion by an experienced observer. CR was defined by greater than or equal to5% improvement of stress compared with rest ejection fraction (EF). Exercise capacity was assessed from expired gas analysis. Results CR was present in 34 patients with mitral regurgitation (47%); peak EF in patients with and without CR was 74% +/- 11% versus 54% +/- 15% (P

A class B switch-mode assisted linear amplifier

A switch-mode assisted linear amplifier (SMALA) combining a linear (Class B) and a switch-mode (Class D) amplifier is presented. The usual single hysteretic controlled half-bridge current dumping stage is replaced by two parallel buck converter stages, in a parallel voltage controlled topology. These operate independently: one buck converter sources current to assist the upper Class B output device, and a complementary converter sinks current to assist the lower device. This topology lends itself to a novel control approach of a dead-band at low power levels where neither class D amplifier assists, allowing the class B amplifier to supply the load without interference, ensuring high fidelity. A 20 W implementation demonstrates 85% efficiency, with distortion below 0.08% measured across the full audio bandwidth at 15 W. The class D amplifier begins assisting at 2 W, and below this value, the distortion was below 0.03%. Complete circuitry is given, showing the simplicity of the additional class D amplifier and its corresponding control circuitry.

Relationships and estimates of longitudinal growth stress in Eucalyptus dunnii at different ages

O objetivo desse trabalho foi obter estimativas da tensão de crescimento longitudinal em árvores vivas e verificar a sua relação com algumas características da madeira de Eucalyptus dunnii Maiden aos oito, treze, quinze e dezenove anos de idade. O material foi proveniente da Empresa Procopiak Compensados e Embalagens S.A., localizada no Município de Canoinhas, Santa Catarina. Os níveis de tensão longitudinal de crescimento foram mensurados indiretamente pelo método do "CIRAD-Forêt", na árvore viva, e estimados a partir do módulo de elasticidade dinâmico e do módulo de elasticidade obtido no ensaio de tração paralela à grã. A deformação residual longitudinal (DRL) e as estimativas das tensões de crescimento longitudinais apresentaram tendência de aumento, na média, com a idade do material. A DRL apresentou correlação, positiva e significativa, com todas as estimativas das tensões de crescimento longitudinais, sendo de maior magnitude aos 13, 15 e 19 anos de idade. A densidade básica apresentou maiores correlações, positivas e significativas, com o módulo de elasticidade dinâmico, estimado no sentido longitudinal, para a madeira na condição de saturação e a 12% de umidade, em todas as idades avaliadas. Todas as estimativas das tensões de crescimento longitudinais apresentam elevadas correlações, positivas e significativas, entre si.

Consumo de álcool e adiposidade abdominal : resultados do estudo longitudinal de saúde do adulto – ELSA Brasil

A acumulação de tecido adiposo abdominal apresenta associação positiva com eventos cardiovasculares, pressão arterial e alterações metabólicas. Dentre os fatores de risco para o aumento da obesidade abdominal está o alto consumo de bebidas alcoólicas, particularmente a cerveja. O objetivo deste estudo foi identificar associação entre consumo de bebidas alcoólicas (CBA) e adiposidade abdominal. Trata-se de uma investigação de corte transversal conduzida a partir da linha de base do Estudo Longitudinal de Saúde do Adulto – ELSA-Brasil, composta por 15.105 indivíduos (35 a 74 anos). Foram analisadas variáveis antropométricas, socioeconômicas e consumo de bebidas alcoólicas e utilizados, para diagnóstico de obesidade abdominal, os pontos de corte da circunferência da cintura (CC) e relação cintura/quadril (RCQ) preconizados pela Organização Mundial de Saúde. O CBA foi categorizado em quintis. Teste de Kolmogorov-Smirnov foi utilizado para avaliar a normalidade das variáveis. A associação entre variáveis antropométricas e o CBA foi avaliada utilizando-se teste Mann-Whitney, Kruskal-Wallis e teste qui-quadrado. Foram testados modelos de regressão linear e Poisson, ajustados por idade, sexo, IMC, tabagismo, atividade física, renda e escolaridade. A CC inadequada foi associada a maior CBA em toda amostra (1,03, IC95% 1,01-1,05) e em homens (1,05, IC95% 1,03-1,08). A RCQ inadequada foi associada a maior CBA tanto para o total da amostra (1,04, IC95% 1,01-1,06) como para mulheres (1,07, IC95% 1,03-1,12). Homens no quinto quintil de consumo de cerveja apresentaram chance 1,05 maior (IC95% 1,02-1,08) de ter a CC inadequada quando comparados aos que se encontravam no primeiro quintil. Já entre as mulheres a chance foi 1,16 (IC95% 1,13-1,20). Homens e mulheres no quinto quintil de consumo de cerveja tinham, respectivamente, 1,03 (IC95% 1,00-1,07) e 1,10 (IC95%1,04-1,15) vezes mais chance de apresentar RCQ inadequada. O consumo de vinho só foi associado a maior chance de ter CC aumentada entre mulheres (β=0,026, p<0,027). Neste estudo, o consumo de álcool foi associado positivamente com obesidade abdominal, sendo mais importante a contribuição da cerveja para aumento da CC e da RCQ.

Avaliação longitudinal do ECAP registrado em crianças usuárias de implante coclear

Em crianças usuárias de Implante Coclear (IC), o registro do potencial de ação composto do nervo auditivo evocado eletricamente (ECAP) representa uma maneira de avaliar as modificações nas respostas neurais e entre o feixe de eletrodos e o tecido neural ao longo do tempo. OBJETIVO: Estudar o ECAP em crianças ao longo do primeiro ano de uso do IC. MATERIAL E MÉTODO: As características do ECAP foram analisadas em 13 crianças, implantadas com idades inferiores a três anos de idade. Estudo de série. RESULTADOS: Houve aumento estatisticamente significante na amplitude do pico N1, nos eletrodos basais, entre o segundo e o terceiro retorno. Não foram obtidas diferenças significantes para: a latência do pico N1, o slope, o p-NRT e o período de recuperação entre os retornos. Nos três retornos, a maioria dos sujeitos apresentou tempo de recuperação entre 1000 e 2000µs. CONCLUSÃO: Ao longo do primeiro ano de uso do IC, a estimulação elétrica liberada pelos eletrodos intracocleares não causou alterações significativas às características do ECAP, exceto pelo aumento da amplitude do pico N1.

Morbidade em creche de Brasília: estudo longitudinal de incidência de enfermidades no ano de 1977

Foi feito estudo longitudinal de morbidade em creche de Brasília (Brasil) freqüentada por crianças com bom estado nutricional. Foram admitidas na creche durante o ano de 1977 o total de 67 crianças (34 do sexo masculino e 33 do sexo feminino), com idade entre 3 e 21 meses. Infecções de vias aéreas superiores (25,4%), diarréia (23,6%) e febre não esclarecida (18,4%) representaram dois terços dos diagnósticos. A seguir, em ordem de freqüência, apareceram conjuntivite (15,5%), viroses da infância (7,9%), doenças de pele (3,8%), pequenos acidentes (2,6%), hepatite (2,6%) e meningococcemia (0,3%). Houve um total de 343 episódios agudos, dando uma taxa de incidência de 14 enfermidades por criança por ano, independente de sexo e idade.

Estudo longitudinal das crianças nascidas em 1982 em Pelotas, RS, Brasil: metodologia e resultados preliminares

Tentou-se acompanhar a morbi-mortalidade e o crescimento de uma coorte de 6.011 crianças urbanas nascidas em 1982 nos hospitais de Pelotas, RS, através de visitas domiciliares aos 12 meses (para uma amostra de 30% das crianças) e aos 20 meses (para toda a população). Estas crianças representaram mais de 99% de todos os nascimentos urbanos naquele ano. Foi possível localizar 81% das crianças aos 12 meses e 86% aos 20 meses, devido a uma mudança na estratégia de trabalho de campo. A metodologia empregada e as principais dificuldades encontradas são descritas e as características ao nascer das crianças localizadas no acompanhamento são comparadas com as características das crianças não localizadas. A potencialidade de uso dos dados coletados é exemplificada através de alguns resultados preliminares mostrando as associações entre o peso ao nascer, a renda familiar e o estado nutricional aos 12 meses. O estudo mostra que é possível acompanhar, com uma perda relativamente pequena, uma coorte de crianças com base populacional em uma cidade brasileira de tamanho médio.

A importância da actividade física em pacientes submetidos a transplante hepático: estudo longitudinal

Prémio da Sociedade Portuguesa de Hepatologia para melhor comunicação oral.

n-Hexane hydroisomerisation over bifunctional Pt/MCM-22 catalysts. Influence of the mode of Pt introduction

Three different methods were used to introduce 1.0 wt.% of Pt in bifunctional Pt/MCM-22 zeolite catalysts: ion exchange with Pt(NH3)(4)(2+), incipient wetness impregnation with PtCl6H2 and mechanical mixture with Pt/Al2O3. The Pt dispersion was estimated by transmission electron microscopy and the hydrogenating activity with toluene hydrogenation at 110 degrees C. From these experiments, it can be concluded that with the ion exchanged sample, platinum was located within the inner micropores and on the outer surface, whereas with the impregnated one, platinum was essentially on the outer surface under the form of large particles. With all the samples there is a fast initial decrease in the activity for n-hexane hydroisomerisation at 250 degrees C. With exchanged and impregnated samples, this decrease is followed by a plateau, the activity value being then higher with impregnated sample. For the sample prepared by mechanical mixture a continuous decrease in activity can be observed. All these differences can be related with the distinct locations of Pt.