RESUMO
HYPOTHESIS: The electrical charges that develop on the surface of the ceramic particles upon contact with water, due to the interaction with ions in solution, result in a liquid-solid interface, which utterly modifies the properties of individual particles and the way they interact with each other to form a structure. This work explores a new approach to the relationships between structure and stability of suspensions. EXPERIMENTS: For this purpose, suspensions with a constant 0.35 volume fraction of α-alumina particles, neither spherical nor smooth, and controlled ionic strength (0-90 mM KCl) were prepared and characterized in terms of flow behaviour, electrical conductivity and particle's electrokinetic mobility. FINDINGS: Electrical conductivity (132 µS/cm < conductivity < 5730 µS/cm) and rheology measurements (10-2 Pa s < viscosity < 104 Pa s) were found to complement each other to produce a more accurate picture of the suspension's structure. Deviations of experimental data from well-accepted behavioural models were elucidated when the surface area equivalent particle size was used. With the electrical double layer thickness obtained from electrical conductivity measurements, this enabled the interpretation of the relationship between the suspension's viscosity and the particles electrical conductivity, which provides a criterion for the stability of concentrated colloidal suspensions.
Assuntos
Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/patologia , Proliferação de Células/fisiologia , Antígeno Ki-67/metabolismo , Neoplasias da Mama/metabolismo , Carcinoma Ductal de Mama/metabolismo , Feminino , Humanos , Imuno-Histoquímica , Prognóstico , Sensibilidade e EspecificidadeRESUMO
BACKGROUND: Vitamin D deficiency may be associated with an increased risk of asthma. OBJECTIVE: We studied the association between 25-hydroxy (25-OH) vitamin D deficiency and asthma prevalence in two Peruvian populations close to the equator but with disparate degrees of urbanization. METHODS: We conducted a population-based study in 1441 children in two communities in Peru, of which 1134 (79%) provided a blood sample for 25-OH vitamin D analysis. RESULTS: In these 1134 children, mean age was 14.8 years; 52% were boys; asthma and atopy prevalence was 12% in Lima vs. 3% in Tumbes (P < 0.001) and 59% in Lima vs. 41% in Tumbes (P < 0.001), respectively; and, mean 25-OH vitamin D level was 20.8 ng/mL in Lima vs. 30.1 ng/mL in Tumbes (P < 0.001). Prevalence of 25-OH vitamin D deficiency (< 20 ng/mL) was 47% in Lima vs. 7% in Tumbes (P < 0.001). In multi-variable logistic regression, we found that lower 25-OH vitamin D levels were associated with an increased odds of asthma (OR = 1.7 per each 10 ng/mL decrease in 25-OH vitamin D levels, 95% CI 1.2-2.6; P < 0.01). In stratified analyses, the association between lower 25-OH vitamin D levels and asthma was limited to children with atopy (OR = 2.2, 95% CI 1.3-3.6) and not in those without atopy (OR = 0.9, 95% CI 0.5-2.0). We did not find associations between 25-OH vitamin D levels and other clinical biomarkers for asthma, including exhaled nitric oxide, total serum IgE and pulmonary function. CONCLUSION AND CLINICAL RELEVANCE: Both asthma and 25-OH vitamin D deficiency were common among children living in Lima (latitude = 12.0 °S) but not among those in Tumbes (3.6 °S). The relationship between 25-OH vitamin D deficiency and asthma was similar in both sites and was limited among children with atopy. Future supplementation trials may need to consider stratification by atopy at the time of design.
Assuntos
Asma/sangue , Asma/epidemiologia , Calcifediol/sangue , Deficiência de Vitamina D/sangue , Deficiência de Vitamina D/epidemiologia , Adolescente , Asma/complicações , Feminino , Humanos , Masculino , Peru/epidemiologia , Deficiência de Vitamina D/complicaçõesRESUMO
BACKGROUND: Allergic rhinitis is a disease with a high global disease burden, but risk factors that contribute to this condition are not well understood. OBJECTIVE: To assess the prevalence and risk factors of allergic rhinitis in two Peruvian populations with disparate degrees of urbanization. METHODS: We conducted a population-based, cross-sectional study on 1441 children aged 13-15 years at enrollment (mean age 14.9 years, 51% boys) to investigate the prevalence of allergic disease. We used a standardized, Spanish validated questionnaire to determine the prevalence of allergic rhinitis and asked about sociodemographics and family history of allergies. Children also underwent spirometry, exhaled nitric oxide, allergy skin testing to 10 common household allergens and provided a blood sample for measurement of 25OH vitamin D and total serum IgE. RESULTS: Overall prevalence of allergic rhinitis was 18% (95% CI 16% to 20%). When stratified by site, the prevalence of allergic rhinitis was 23% Lima vs. 13% in Tumbes (P < 0.001); however, this difference was no longer significant after controlling for subject-specific factors (P = 0.95). There was a strong association with other allergic diseases: 53% of children with asthma had allergic rhinitis vs. 15% in those without asthma (P < 0.001) and 42% of children with eczema vs. 17% of those without eczema (P < 0.001). Important risk factors for allergic rhinitis were parental rhinitis (adjusted OR = 3.0, 95% CI 1.9-4.7 for 1 parent and adjusted OR = 4.4, 95% CI 1.5-13.7 for 2 parents); allergic sensitization to common household aeroallergens (1.6, 1.1-2.3); being overweight (1.5, 1.0-2.3); exhaled nitric oxide ≥ 20 ppb (1.9, 1.3-2.7); and total serum IgE ≥ 95th percentile (2.4, 1.2-4.8). Population attributable risk of important factors for allergic rhinitis were 25% for high exhaled nitric oxide, 22% for allergic sensitization to common household aeroallergens, 22% for paternal rhinitis, 10% for being overweight and 7% for an elevated total serum IgE. CONCLUSION AND CLINICAL RELEVANCE: Allergic rhinitis was prevalent in both settings, and important risk factors include elevated exhaled nitric oxide, allergic sensitization to common household aeroallergens, parental rhinitis, being overweight and high total serum IgE. When considering subject-specific factors, the difference in prevalence between the urban and rural settings became non-important.
Assuntos
Exposição Ambiental/efeitos adversos , Rinite Alérgica/epidemiologia , População Rural , Inquéritos e Questionários , População Urbana , Adolescente , Estudos Transversais , Feminino , Humanos , Masculino , Peru/epidemiologia , Prevalência , Rinite Alérgica/etiologia , Fatores de RiscoRESUMO
A novel parasitoid ciliate, Pseudocollinia brintoni gen. nov., sp. nov. was discovered infecting the subtropical sac-spawning euphausiid Nyctiphanes simplex off both coasts of the Baja California peninsula, Mexico. We used microscopic, and genetic information to describe this species throughout most of its life cycle. Pseudocollinia is distinguished from other Colliniidae genera because it exclusively infects euphausiids, has a polymorphic life cycle, and has a small cone-shaped oral cavity whose left wall has a field of ciliated kinetosomes and whose opening is surrounded on the left and right by 2 'oral' kineties (or ciliary rows) that terminate at its anterior border. Two related species that infect different euphausiid species from higher latitudes in the northeastern Pacific Ocean, Collinia beringensis Capriulo and Small, 1986, briefly redescribed herein, and Collinia oregonensis Gómez-Gutiérrez, Peterson, and Morado, 2006, are transferred to the genus Pseudocollinia. P. brintoni has between 12 and 18 somatic kineties, and its oral cavity has only 2 oral kineties, while P. beringensis comb. nov. has more somatic kineties, including 3 oral kineties. P. oregonensis comb. nov. has an intermediate number of somatic kineties. P. beringensis comb. nov. also infects Thysanoessa raschi (a new host species). SSU rRNA and cox1 gene sequences demonstrated that Pseudocollinia ciliates are apostome ciliates and that P. brintoni is different from P. beringensis comb. nov. High densities of rod-shaped bacteria (1.7 µm length, 0.2 to 0.5 µm diameter) were associated with P. brintoni. After euphausiid rupture, high concentrations of P. brintoni and bacteria cluster to form 3 to 6 cm long filaments where tomites encyst and transform to the phoront stage; this is a novel place for encystation. P. brintoni may complete its life cycle when the euphausiids feed on these filaments.
Assuntos
Cilióforos/isolamento & purificação , Euphausiacea/parasitologia , Animais , Cilióforos/classificação , Ciclo-Oxigenase 1/genética , Ciclo-Oxigenase 1/metabolismo , DNA Ribossômico/genética , Feminino , Interações Hospedeiro-Parasita , México , FilogeniaRESUMO
In March 1996, a survey of hydrothermal sites on the island of Montserrat was carried out. Six sites (Galway's Soufrière. Gages Upper and Lower Soufrières, Hot Water Pond, Hot River, and Tar River Soufrière) were mapped and sampled for chemical, ATP, and microbial analyses. The hydrothermal Soufrière sites on the slopes of the active Chances Peak volcano exhibited temperatures up to almost 100 degrees C and were generally either mildly acidic at pH 5-7 or strongly acidic at pH 1.5-3, but with some hot streams and pools of low redox potential at pH 7-8. Hot Water Pond sites, comprising a series of heated pools near the western shoreline of the island. were neutral and saline, consistent with subsurface heating of entrained seawater. Biological activity shown by ATP analyses was greatest in near-neutral pH samples and generally decreased as acidity increased. A variety of heterotrophic and chemolithotrophic thermophilic organisms were isolated or observed in enrichment cultures. Most of the bacteria that were obtained in pure culture were familiar acidophiles and neutrophiles, but novel, iron-oxidizing species of Sulfobacillus were revealed. These species included the first mesophilic iron-oxidizing Sulfobacillus strains to be isolated and a strain with a higher maximum growth temperature (65 degrees C) than the previously described moderately thermophilic Sulfobacillus species.
Assuntos
Água Doce/microbiologia , Água do Mar/microbiologia , Trifosfato de Adenosina/análise , Bacillus/classificação , Bacillus/genética , Bacillus/isolamento & purificação , Técnicas de Tipagem Bacteriana , DNA Arqueal/análise , DNA Bacteriano/análise , DNA Ribossômico/análise , Ecologia , Água Doce/química , Geografia , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiologia , Temperatura Alta , Concentração de Íons de Hidrogênio , RNA Ribossômico 16S/análise , Água do Mar/química , Sulfolobus/classificação , Sulfolobus/genética , Sulfolobus/isolamento & purificação , Índias OcidentaisRESUMO
Misfolding and misassembly of proteins are major problems in the biotechnology industry, in biochemical research, and in human disease. Here we describe a novel approach for reversing aggregation and increasing refolding by application of hydrostatic pressure. Using P22 tailspike protein as a model system, intermediates along the aggregation pathway were identified and quantitated by size-exclusion high-performance liquid chromatography (HPLC). Tailspike aggregates were subjected to hydrostatic pressures of 2.4 kbar (35,000 psi). This treatment dissociated the tailspike aggregates and resulted in increased formation of native trimers once pressure was released. Tailspike trimers refolded at these pressures were fully active for formation of infectious viral particles. This technique can facilitate conversion of aggregates to native proteins without addition of chaotropic agents, changes in buffer, or large-scale dilution of reagents required for traditional refolding methods. Our results also indicate that one or more intermediates at the junction between the folding and aggregation pathways is pressure sensitive. This finding supports the hypothesis that specific determinants of recognition exist for protein aggregation, and that these determinants are similar to those involved in folding to the native state. An increased understanding of this specificity should lead to improved refolding methods.
Assuntos
Glicosídeo Hidrolases/química , Proteínas da Cauda Viral/química , Cromatografia em Gel , Cromatografia Líquida de Alta Pressão , Eletroforese em Gel de Poliacrilamida , Pressão Hidrostática , Conformação Proteica , Dobramento de Proteína , Espectrometria de FluorescênciaRESUMO
Sixty-eight patients had Norplant inserted between May 1992 and November 1993 as part of a pre-introductory study. The main side effect was weight change which occurred in 85.3% (58 patients); weight loss occurred in 25.0% (17 patients, one patient voiced a complaint) and weight gain occurred in 60.3% (41 patients, 10 of whom voiced a complaint). Menstrual problems were the next most frequent side effect occurring in 70.4% (48 patients); spotting occurring in 22% (15 patients, none of whom complained) and heavy bleeding in 7.3% (five patients, all of whom complained). Amenorrhoea occurred in 41.1% (28 patients). Other complaints were minor. No pregnancies have been recorded to date. There were no procedural complications and all patients were satisfied with the cosmetic appearance. To date there have been 36 removals, the majority for menstrual complications. Norplant is a safe, effective means of 'reversible sterilisation' which should be utilised in family planning programmes throughout the country.
RESUMO
A 10-day-old infant with stridor was found to have herpes simplex virus type 2 infection of the larynx. The infant's poor clinical response to both acyclovir and foscarnet prompted extensive clinical and virologic evaluations, which revealed acyclovir-resistant herpes simplex virus.
Assuntos
Aciclovir/uso terapêutico , Herpes Simples/tratamento farmacológico , Herpesvirus Humano 2/efeitos dos fármacos , Doenças da Laringe/tratamento farmacológico , Aciclovir/farmacologia , Resistência Microbiana a Medicamentos , Feminino , Foscarnet/uso terapêutico , Herpesvirus Humano 2/isolamento & purificação , Humanos , Recém-Nascido , Doenças da Laringe/microbiologiaAssuntos
Aqueduto do Mesencéfalo/patologia , Encefalite/complicações , Hidrocefalia/etiologia , Mononucleose Infecciosa/complicações , Criança , Constrição Patológica , Encefalite/patologia , Herpesvirus Humano 4/isolamento & purificação , Humanos , Hidrocefalia/cirurgia , Mononucleose Infecciosa/patologia , Masculino , Sinusite/etiologia , Derivação VentriculoperitonealRESUMO
É descrita a experiência inicial do Instituto do Coraçäo de Pernambuco, na unidade de terapia intensiva neonatal, com realizaçäo de septostomia Rashkind, sob monitorizaçäo ecocardiográfica, através de acesso percutâneo (punçäo da veia femoral), sob anestesia local, constando dos três primeiros casos, sendo dois neonatos com transposiçäo das grandes artérias e um com atresia tricúspide. Em dois pacientes, obteve-se sucesso tanto na técnica quanto na melhora hemodinâmica após o procedimento. No 3§ paciente com 36 dias de vida, o septo atrial encontrava-se rijo näo permitindo ampliaçäo satisfatória. Nenhum dos procedimentos apresentou complicaçöes significantes durante a sua realizaçäo. Apesar da pequena amostragem, nossa experiência demonstrou que esta nova abordagem para a realizaçäo da atrioseptostomia Rashkind é exeqüível, sem maiores complicaçöes para o neonato, e com benefícios sobre a técnica convencional
Assuntos
Humanos , Masculino , Feminino , Recém-Nascido , Lactente , Veia Femoral/cirurgia , Cateterismo Periférico/métodos , Cateterismo , Unidades de Terapia Intensiva Neonatal , Veia Femoral , Átrios do Coração/cirurgia , Átrios do Coração , Cardiopatias Congênitas/terapia , Septos Cardíacos/cirurgia , Septos CardíacosRESUMO
PIP: For the past 25 years the Albert Schweitzer Hospital in Deschapelles, Haiti has been providing a wide range of maternal and child health services to the people of its rural district. Numerous special services for mothers and children have been added over the years, but these began to realize considerably greater potential with the creation of the hospital's Community Health Department in 1967. This department has carried out numerous preventive health programs and services designed to accommodate these groups' special health needs. Attention is directed to neonatal tetanus control; surveillance, treatment, and prevention of malnutrition; and other maternal and child health services (school programs, immunization activities, prenatal and postnatal care, family planning, the midwives' program, the "cord-cut" unit, the low birth weight project, and dispensaries and health agents). In 1967 the hospital began to develop programs especially designed to control neonatal tetanus. Communities were immunized systematically. By establishing outdoor immunization clinics at the hospital and at major marketplaces in the district and by working with traditional midwives, these programs were responsible for a sharp decline in the incidence of neonatal tetanus. Malnutrition has remained the most frequently occurring health problem among children in the hospital district. Several services and programs have been established throughout the years to meet the identified needs. These include the following which are described: the nutrition clinic; courtyard education; "weigh-ins;" nutrition recovery centers; the 3-day center at Deschapelles; nutrition intervention and case follow-up program; and malnutrition treatment. The hospital's family planning program has gradually increased its use of community education to reach the population and to try to gain acceptance of the need to space and limit births. This community education has been disseminated by dispensaries, mobile health team workers, public health nurses, and physicians. Implementation of immunization, health surveillance, health education, and improved tuberculosis control activities have produced gratifying reductions in overall maternal and child morbidity and mortality in the Schweitzer hospital district.^ieng