RESUMEN
BACKGROUND: Cost-effectiveness of calcium supplementation depends not only on the cost of the product but on the efficiency of its absorption. Published cost-benefit analyses assume equal bioavailability for all calcium sources. Some published studies have suggested that there are differences in both the bioavailability and cost of the major calcium supplements. DESIGN: Randomized four period, three-way cross-over comparing single doses of off-the-shelf commercial calcium supplements containing either calcium carbonate or calcium citrate compared with a no-load blank and with encapsulated calcium carbonate devoid of other ingredients; subjects rendered fully vitamin D-replete with 10 microg/day 25(OH)D by mouth, starting one week prior to the first test. SUBJECTS: 24 postmenopausal women METHODS: Pharmacokinetic analysis of the increment in serum total and ionized calcium and the decrement in serum iPTH induced by an oral calcium load, based upon multiple blood samples over a 24-hour period; measurement of the rise in urine calcium excretion. Data analyzed by repeated measures ANOVA. Cost calculations based on average retail prices of marketed products used in this study from April through October, 2000. RESULTS: All three calcium sources (marketed calcium carbonate, encapsulated calcium carbonate and marketed calcium citrate) produced identical 24-hour time courses for the increment in total serum calcium. Thus, these were equally absorbed and had equivalent bioavailability. Urine calcium rose slightly more with the citrate than with the carbonate preparations. but the difference was not significant. Serum iPTH showed the expected depression accompanying the rise in serum calcium, and there were no significant differences between products. CONCLUSION: Given the equivalent bioavailability of the two marketed products, the cost benefit analysis favors the less expensive carbonate product.
Asunto(s)
Calcio de la Dieta/economía , Calcio de la Dieta/farmacocinética , Calcio/análisis , Suplementos Dietéticos/economía , Área Bajo la Curva , Disponibilidad Biológica , Carbonato de Calcio/administración & dosificación , Carbonato de Calcio/economía , Carbonato de Calcio/farmacocinética , Citrato de Calcio/administración & dosificación , Citrato de Calcio/economía , Citrato de Calcio/farmacocinética , Calcio de la Dieta/administración & dosificación , Análisis Costo-Beneficio , Estudios Cruzados , Femenino , Fracturas Óseas/prevención & control , Humanos , Absorción Intestinal , Persona de Mediana Edad , Osteoporosis Posmenopáusica/prevención & control , PosmenopausiaRESUMEN
The MinC protein directs placement of the division septum to the middle of Escherichia coli cells by blocking assembly of the division apparatus at other sites. MinD and MinE regulate MinC activity by modulating its cellular location in a unique fashion. MinD recruits MinC to the membrane, and MinE induces MinC/MinD to oscillate rapidly between the membrane of opposite cell halves. Using fixed cells, we previously found that a MinE-green fluorescent protein fusion accumulated in an annular structure at or near the midcell, as well as along the membrane on only one side of the ring. Here we show that in living cells, MinE undergoes a rapid localization cycle that appears coupled to MinD oscillation. The results show that MinE is not a fixed marker for septal ring assembly. Rather, they support a model in which MinE stimulates the removal of MinD from the membrane in a wave-like fashion. These waves run from a midcell position towards the poles in an alternating sequence such that the time-averaged concentration of division inhibitor is lowest at midcell.
Asunto(s)
Adenosina Trifosfatasas/metabolismo , Proteínas Bacterianas/metabolismo , Proteínas del Citoesqueleto , Proteínas de Escherichia coli , Adenosina Trifosfatasas/genética , Proteínas Bacterianas/genética , Proteínas Bacterianas/fisiología , Ciclo Celular , Proteínas de Ciclo Celular , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas Fluorescentes Verdes , Proteínas Luminiscentes/genética , Modelos Biológicos , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismoRESUMEN
FtsZ and ZipA are essential components of the septal ring apparatus, which mediates cell division in Escherichia coli. FtsZ is a cytoplasmic tubulin-like GTPase that forms protofilament-like homopolymers in vitro. In the cell, the protein assembles into a ring structure at the prospective division site early in the division cycle, and this marks the first recognized event in the assembly of the septal ring. ZipA is an inner membrane protein which is recruited to the nascent septal ring at a very early stage through a direct interaction with FtsZ. Using affinity blotting and protein localization techniques, we have determined which domain on each protein is both sufficient and required for the interaction between the two proteins in vitro as well as in vivo. The results show that ZipA binds to residues confined to the 20 C-terminal amino acids of FtsZ. The FtsZ binding (FZB) domain of ZipA is significantly larger and encompasses the C-terminal 143 residues of ZipA. Significantly, we find that the FZB domain of ZipA is also required and sufficient to induce dramatic bundling of FtsZ protofilaments in vitro. Consistent with the notion that the ability to bind and bundle FtsZ polymers is essential to the function of ZipA, we find that ZipA derivatives lacking an intact FZB domain fail to support cell division in cells depleted for the native protein. Interestingly, ZipA derivatives which do contain an intact FZB domain but which lack the N-terminal membrane anchor or in which this anchor is replaced with the heterologous anchor of the DjlA protein also fail to rescue ZipA(-) cells. Thus, in addition to the C-terminal FZB domain, the N-terminal domain of ZipA is required for ZipA function. Furthermore, the essential properties of the N domain may be more specific than merely acting as a membrane anchor.
Asunto(s)
Proteínas Bacterianas/metabolismo , Proteínas Portadoras/metabolismo , Proteínas de Ciclo Celular/metabolismo , Proteínas del Citoesqueleto , Proteínas de Escherichia coli , Escherichia coli/fisiología , Secuencia de Aminoácidos , Proteínas Bacterianas/genética , Proteínas Bacterianas/ultraestructura , Sitios de Unión , Proteínas Portadoras/química , Proteínas Portadoras/genética , Proteínas de Ciclo Celular/química , Proteínas de Ciclo Celular/genética , División Celular , Clonación Molecular , Escherichia coli/citología , Escherichia coli/genética , GTP Fosfohidrolasas/química , GTP Fosfohidrolasas/metabolismo , Sustancias Macromoleculares , Datos de Secuencia Molecular , Mutagénesis Sitio-Dirigida , Fragmentos de Péptidos/química , Fragmentos de Péptidos/metabolismo , Reacción en Cadena de la Polimerasa , Proteínas Recombinantes/química , Proteínas Recombinantes/aislamiento & purificación , Proteínas Recombinantes/metabolismoRESUMEN
Cell division in prokaryotes is mediated by the septal ring. In Escherichia coli, this organelle consists of several essential division proteins, including FtsZ, FtsA, and ZipA. To gain more insight into how the structure is assembled, we studied the interdependence of FtsZ, FtsA, and ZipA localization using both immunofluorescence and Gfp tagging techniques. To this end, we constructed a set of strains allowing us to determine the cellular location of each of these three proteins in cells from which one of the other two had been specifically depleted. Our results show that ZipA fails to accumulate in a ring shape in the absence of FtsZ. Conversely, depletion of ZipA does not abolish formation of FtsZ rings but leads to a significant reduction in the number of rings per unit of cell mass. In addition, ZipA does not appear to require FtsA for assembly into the septal ring and vice versa. It is suggested that septal ring formation starts by assembly of the FtsZ ring, after which ZipA and FtsA join this structure in a mutually independent fashion through direct interactions with the FtsZ protein.
Asunto(s)
Proteínas Bacterianas/metabolismo , Proteínas Portadoras/metabolismo , Proteínas de Ciclo Celular/metabolismo , Proteínas del Citoesqueleto , Proteínas de Escherichia coli , Escherichia coli/citología , Escherichia coli/metabolismo , Secuencia de Aminoácidos , Proteínas Bacterianas/genética , Proteínas Portadoras/genética , Proteínas de Ciclo Celular/genética , División Celular , Escherichia coli/genética , Inmunohistoquímica , Microscopía Fluorescente , Microscopía de Interferencia , Orgánulos/metabolismoRESUMEN
This paper describes a new classification of ward organizational practice in nursing. Data related to aspects of ward nursing practice were collected by postal survey from a nationally representative sample of 74 acute hospital wards, and subjected to hierarchical cluster analysis. The model which was deemed to best 'fit' the data, provided three types of ward practices, which have been named: 'devolved', 'two tier' and 'centralized' nursing. The distinguishing features of the three classifications are similar but not identical to accepted 'ideal types' of primary, team and functional systems. The relationships between wards in each of the three identified categories and other ward organizational practice processes of nursing care and job satisfaction are described.
Asunto(s)
Satisfacción en el Trabajo , Servicio de Enfermería en Hospital/organización & administración , Personal de Enfermería en Hospital/organización & administración , Análisis de Varianza , Análisis por Conglomerados , Análisis Discriminante , Inglaterra , Humanos , Relaciones Interprofesionales , Modelos Organizacionales , Práctica ProfesionalRESUMEN
This paper describes a study which was designed to test the feasibility of using retrospective case note abstraction of data from nursing records to identify the nursing interventions given to two groups of patients: those who had suffered a myocardial infarction and those who had sustained a fractured neck of femur. The aim of the study was to assess whether the data obtained from the records were an accurate reflection of the nursing care given to patients. This was done by comparing what was recorded in the notes for specific areas of care with what the nursing staff said they did. The specific areas of care for patients suffering a myocardial infarction were: pain, mobility, anxiety, patient education. The specific areas of care for patients sustaining a fractured femur were: pressure areas, pain, nutrition, mobility and rehabilitation, information and teaching. Data were collected in three ways: using a retrospective data abstraction tool to examine the case notes of a particular patient; interviewing a nurse who had looked after the same patient; interviewing a senior ward nurse to obtain information about ward policies and practices to obtain a profile of the care usually given to these groups of patients. In this paper we present some of our findings and discuss the methodological and logistical problems of using this method.
Asunto(s)
Auditoría de Enfermería/métodos , Investigación en Evaluación de Enfermería/métodos , Registros de Enfermería , Estudios de Factibilidad , Fracturas del Cuello Femoral/enfermería , Humanos , Infarto del Miocardio/enfermería , Auditoría de Enfermería/normas , Investigación en Evaluación de Enfermería/normas , Reproducibilidad de los Resultados , Estudios RetrospectivosRESUMEN
FtsZ is a soluble, tubulin-like GTPase that forms a membrane-associated ring at the division site of bacterial cells. While this ring is thought to drive cell constriction, it is not well understood how it is assembled or how it affects cell wall invagination. Here we report that FtsZ binds directly to a novel integral inner membrane protein in E. coli that we call ZipA. We present genetic and morphological evidence indicating that this interaction is required for cell division, and show that a fluorescent ZipA-Gfp fusion protein is located in a ring structure at the division site, both before and during cell wall invagination. ZipA is an essential component of the division machinery, and, by binding to both FtsZ and the cytoplasmic membrane, is likely to be directly involved in the assembly and/or function of the FtsZ ring.
Asunto(s)
Proteínas Bacterianas/metabolismo , División Celular , Proteínas del Citoesqueleto , Escherichia coli/citología , Proteínas de Unión al GTP/metabolismo , Proteínas de la Membrana/metabolismo , Secuencia de Aminoácidos , Secuencia de Bases , Membrana Celular/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Expresión Génica , Genes Bacterianos , Lisogenia , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Datos de Secuencia Molecular , Fenotipo , Proteínas Recombinantes de Fusión/metabolismoRESUMEN
The sequences of a 1.8-kbp macronuclear DNA molecule (V3), and the majority of its micronuclear counterpart, are reported. The macronuclear V3 DNA molecule contains an open reading frame that is interrupted by a single intron, while the micronuclear copy is interrupted by four internal eliminated sequences, one of which is located within the intron. The predicted protein product of the macronuclear V3 gene is a 471-amino acid polypeptide that is very similar to a group of protein-serine/threonine kinases from both plant and animal species, some of whose members appear to be involved in cell cycle or growth control.
Asunto(s)
Euplotes/enzimología , Proteínas Serina-Treonina Quinasas/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Núcleo Celular/genética , ADN Protozoario/análisis , Euplotes/genética , Genes Protozoarios , Humanos , Micronúcleo Germinal/genética , Datos de Secuencia Molecular , Homología de Secuencia de AminoácidoRESUMEN
The development of memory strategy use in children with and without mental retardation was investigated. Strategy use, recall, metamemory, and attributional beliefs were assessed over a 3-year period beginning at 10 years of age. Although both groups employed effective strategies and increased their use of these strategies across years, students without mental retardation were more strategic. Although strategy use was a significant predictor of recall for both groups, attributional beliefs and metamemory predicted recall only for the students without retardation in Years 2 and 3, respectively. Slight differences emerged as a function of intelligence in the types of strategies used as well as the ways in which strategy knowledge and beliefs were associated with memory performance.
Asunto(s)
Inteligencia , Trastornos de la Memoria/diagnóstico , Memoria , Niño , Desarrollo Infantil , Humanos , Discapacidad Intelectual/complicaciones , Trastornos de la Memoria/complicaciones , Recuerdo MentalRESUMEN
The first part of this article described some of the tools of a managed care system. This article suggests ways in which the nursing role can be developed to take forward the opportunities offered by managed care.
Asunto(s)
Programas Controlados de Atención en Salud/organización & administración , Planificación de Atención al Paciente , HumanosRESUMEN
Managed care is a clinical system that is currently gaining popularity in the UK. The emphasis is on quality patient care and containment of costs by reducing fragmentation of care delivery. This article describes some of the tools of a managed care system and will focus on a description of a care map and the background to the development of the concept.
RESUMEN
Cornfield's test-based method of setting a confidence interval on a parameter associated with a two-by-two contingency table is adapted for use with the measure of agreement kappa. One-sided confidence intervals derived in this way are compared to other intervals proposed for kappa under two study designs. Both designs involve two ratings per subject on a dichotomous scale. In one design the same two raters make all evaluations; in the other, possibly different pairs of raters evaluate different subjects, or the same rater carries out a pair of independent assessments for each subject. It is shown through simulation that lower bounds based on Cornfield's test-based method attain the nominal coverage probability more often than other intervals proposed in the literature.
Asunto(s)
Seropositividad para VIH/epidemiología , Modelos Estadísticos , Humanos , Masculino , Matemática , Núcleo Familiar , Probabilidad , Proyectos de InvestigaciónRESUMEN
Chimpanzee secretory immunoglobulin A (SIgA) was separated into two fractions by chromatography using the terminal galactose-binding lectin Jacalin. The SIgA fraction bound by Jacalin was cleaved by Haemophilus influenzae IgA1 protease, whereas the SIgA nonbinding fraction was not cleaved. It is proposed that these fractions represent IgA1 and IgA2 subclasses because the presence or absence of galactose-terminal oligosaccharides (Jacalin binding) and susceptibility or resistance to IgA1 protease are properties that define human IgA1 and IgA2 subclasses.
Asunto(s)
Inmunoglobulina A Secretora/análisis , Leche/inmunología , Pan troglodytes/inmunología , Animales , Femenino , Inmunoglobulina A Secretora/clasificaciónRESUMEN
Immunoglobulin (Ig)A proteases synthesized by human mucosal pathogens have a unique specificity for human IgA and will not cleave IgA from other species. In contrast, animal pathogens have not reliably been shown to cleave IgA of the animals they infect. This lack of an animal model has prevented an understanding of the importance of IgA1 proteases as virulence factors. One strategy to develop an animal model would be to identify a species capable of infection by a human IgA-producing pathogen whose IgA was susceptible to cleavage by IgA1 protease of that bacterium. The chimpanzee can be infected with Haemophilus influenzae and is closely related immunologically to man. For these reasons it was sought to determine whether chimpanzee secretory IgA (SIgA) is susceptible to cleavage by IgA1 protease of H. influenzae. This report shows that chimpanzee SIgA can indeed be cleaved at the hinge region by H. influenzae IgA1 protease into Fab alpha and (Fc alpha)2.SC fragments. The susceptibility of chimpanzee SIgA to IgA1 protease of a human pathogen could serve as the basis of an animal model to determine the importance of IgA1 protease in pathogenesis.
Asunto(s)
Haemophilus influenzae/enzimología , Inmunoglobulina A Secretora/metabolismo , Péptido Hidrolasas/metabolismo , Serina Endopeptidasas , Animales , Western Blotting , Cromatografía de Afinidad , Electroforesis en Gel de Poliacrilamida , Femenino , Haemophilus influenzae/patogenicidad , Fragmentos Fab de Inmunoglobulinas/metabolismo , Fragmentos Fc de Inmunoglobulinas/metabolismo , Pan troglodytes , VirulenciaRESUMEN
A picture-naming task was used to examine word-finding problems in language-impaired children. The subjects included 20 language-impaired children, 20 normal children matched to the language-impaired children for chronological age, and 20 normal children matched to the language-impaired children on a composite index of language age. Children were shown 64 pictures of objects and asked to name each as rapidly as possible. The principal findings were that (a) pictures of objects with more frequently occurring names were named more rapidly than pictures of objects with less frequently occurring names; (b) language-imparied children named pictures less rapidly than their chronological-age peers but more rapidly than their language-age peers; and (c) the effects of frequency of occurrence on naming time were comparable for all three groups of children. Factors that may have accounted for the findings are discussed.