RESUMEN
BACKGROUND/OBJECTIVES: Traditional tetrapolar bioimpedance spectroscopy (BIS) is performed with the participant supine for 10 min. New vertical analyzers are penetrating clinical, home and fitness markets, but have body water values that differ from supine reference measures. The minimum time standing prior to assessment does not appear in the literature. We investigated the time course of body water shifts in healthy adults undergoing 30-min assessments in supine and vertical positions. SUBJECTS/METHODS: While seated, participants were prepped for standard tetrapolar electrode placement. Starting position was counterbalanced and body water measurements were taken every 5 min for 30 min in both positions. Participants sat for 2 min prior to switching positions. Of the 64 participants, three were unable to stand for 30 min; their data were excluded. Body size differences were minimized via computation of relative (%) change between time intervals for total body water (TBW), extracellular water (ECW) and intracellular water (ICW). RESULTS: ECW and ICW shifted in opposite directions while participants were supine; as ECW decreased at each time point, ICW increased (P<0.0125). Likewise, when participants stood, ECW increased incrementally (P<0.0125), but the decreases in ICW were not significant. At each time interval, the changes in supine ECW and ICW differed from the standing values (P<0.05). No postural or time differences were found for %change TBW. CONCLUSIONS: For TBW, 5 min appears sufficient for fluid stabilization in either position. Supine ECW and ICW stabilization require more than 30 min as does standing ECW.
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Agua Corporal , Líquido Extracelular/fisiología , Líquido Intracelular/fisiología , Postura/fisiología , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Posición Supina/fisiología , Factores de TiempoRESUMEN
The present study investigated the prevalence and diagnostic potential of the most commonly reported mutations associated with isoniazid resistance, katG 315Thr, katG 315Asn, inhA -15T, inhA -8A, and the oxyR-ahpC intergenic region, in a population sample of 202 isoniazid-resistant Mycobacterium tuberculosis isolates and 176 randomly selected fully sensitive isolates from England and Wales identified by using a directed oligonucleotide array and limited DNA sequencing. The strains were recovered from patients originating from 29 countries; 41 isolates were multidrug resistant. Mutations affecting katG 315, the inhA promoter, and the oxyR-ahpC intergenic region were found in 62.7, 21.9, and 30% of 169 genotypically distinct isoniazid-resistant isolates, respectively, whereas they were found in 0, 0, and 8% of susceptible strains, respectively. The frequency of mutation at each locus was unrelated to the resistance profile or previous antituberculous drug therapy. The commonest mutation in the oxyR-ahpC intergenic region, ahpC -46A, was present in 23.7% of isoniazid-resistant isolates and 7.5% of susceptible isolates. This proved to be a phylogenetic marker for a subgroup of M. tuberculosis strains originating on the Indian subcontinent, which shared IS6110-based restriction fragment length polymorphism and spoligotype features with the Delhi strain and Central Asian strain CAS1; and this marker is strongly associated with isoniazid resistance and the katG 315Thr mutation. In total, 82.8% of unrelated isoniazid-resistant isolates could be identified by analysis of just two loci: katG 315 and the inhA promoter. Analysis of the oxyR-ahpC intergenic region, although phylogenetically interesting, does not contribute significantly to further identification of isoniazid-resistant isolates.
Asunto(s)
Antituberculosos/farmacología , Farmacorresistencia Bacteriana/genética , Isoniazida/farmacología , Mycobacterium tuberculosis/efectos de los fármacos , Peroxidasas/genética , Filogenia , Polimorfismo Genético , Proteínas Bacterianas/genética , Inglaterra , Humanos , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/aislamiento & purificación , Hibridación de Ácido Nucleico , Análisis de Secuencia por Matrices de Oligonucleótidos , Peroxirredoxinas , Análisis de Secuencia de ADN , GalesRESUMEN
PURPOSE: The purpose of this study was to verify the validity of an air displacement plethysmography device (Bod Pod) for estimating body density (Db). METHODS: The Db from the Bod Pod (DbBP) was compared with the Db from hydrostatic weighing (DbHW) at residual lung volume in a heterogeneous sample of 30 black men who varied in age (32.0 +/- 7.7 yr), height (180.3 +/- 7.5 cm), body mass (84.2 +/- 15.0 kg), body fatness (16.1 +/- 7.5%), and self-reported physical activity level and socioeconomic status. The Db for each method was converted to relative body fat (%BF) using race-specific conversion formulas and subsequently compared with %BF obtained from dual-energy x-ray absorptiometry (%BFDXA). RESULTS: Linear regression, using DbHW as the dependent variable and DbBP as the predictor, produced an R2 = 0.84 and SEE = 0.00721 g x cc(-1). However, the mean difference between the two methods (0.00450 +/- 0.00718 g x cc(-1) was significant (P < 0.01). The Bod Pod underestimated the Db of 73% of the sample. The %BF estimates from the Bod Pod, HW, and DXA differed significantly (P < 0.01). The average %BFBP (17.7 +/- 7.4%) was significantly greater than %BFHW (15.8 +/- 7.5%) and %BFDXA (16.1 +/- 7.5%); however, there was no significant difference between %BFHW and %BFDXA. CONCLUSION: The Bod Pod significantly and systematically underestimated Db, resulting in an overestimation of %BF. More cross-validation research is needed before recommending the Bod Pod as a reference method.
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Composición Corporal , Pletismografía/métodos , Absorciometría de Fotón , Adulto , Humanos , Masculino , Sensibilidad y EspecificidadRESUMEN
LIV-I, a high-affinity system that transports neutral, branched-chain amino acids into Escherichia coli, has two components, LivG and LivF, that are homologous to the cystic fibrosis (CF) transmembrane conductance regulator (CFTR). CF-associated mutations of human CFTR were introduced into corresponding regions of LivG, and their effects on leucine transport could be grouped into three classes. Mutations were found that (i) abolished LIV-I--directed transport, (ii) retained about a quarter of wild-type activity at the Michaelis-Menten constant (KM), and (iii) had minimal activity at the KM. A mutation equivalent to a benign polymorphism had no effect on transport. The correlation of these mutational phenotypes in LivG and CFTR suggests that the LIV-I prokaryotic transporter is functionally similar to the CF protein and that this similarity can be exploited to clarify the properties of the nucleotide-binding fold in this superfamily of proteins.
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Proteínas Bacterianas/genética , Fibrosis Quística/genética , Proteínas de Escherichia coli , Proteínas de la Membrana/genética , Proteínas de Transporte de Membrana , Transportadoras de Casetes de Unión a ATP , Secuencia de Aminoácidos , Transporte Biológico Activo , Clonación Molecular , Regulador de Conductancia de Transmembrana de Fibrosis Quística , Análisis Mutacional de ADN , Escherichia coli/genética , Humanos , Cinética , Leucina/metabolismo , Datos de Secuencia Molecular , Unión Proteica , Mapeo Restrictivo , Alineación de Secuencia , Relación Estructura-ActividadAsunto(s)
Proteínas Bacterianas , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , ADN/metabolismo , Escherichia coli/metabolismo , Mutagénesis , Mutación , Proteínas Represoras/metabolismo , Triptófano Sintasa/metabolismo , Secuencia de Aminoácidos , Escherichia coli/genética , Genes Bacterianos , Genes Sintéticos , Indicadores y Reactivos , Datos de Secuencia Molecular , Mutagénesis Sitio-Dirigida , Proteínas Represoras/genética , Triptófano Sintasa/genéticaRESUMEN
The nucleotide sequence of the genes encoding the high affinity, branched-chain amino acid transport systems LIV-I and LS has been determined. Seven genes are present on a 7568-base pair DNA fragment, six of which participate directly in branched-chain amino acid transport. Two periplasmic amino acid-binding proteins are encoded by the livJ (LIV-BP) and livK (LS-BP) genes. These two proteins confer specificity on the LIV-I and LS transport systems. livK is the first gene in a polycistronic message that includes four genes encoding membrane components, livHMGF. The protein products of the livHMGF genes are shared by the two systems. An analysis of the livH and livM DNA sequences suggests that they encode hydrophobic proteins capable of spanning the membrane several times. The LivG and LivF proteins are less hydrophobic, but are also tightly associated with the membrane. Both LivG and LivF contain the consensus sequence for adenine nucleotide binding observed in many other transport proteins. A deletion strain that does not express any of the liv genes was constructed. This strain was used to show that each of the membrane component genes is required for high affinity leucine transport, including two genes, livM and livF, for which no previous genetic evidence had been obtained.
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Aminoácidos de Cadena Ramificada/metabolismo , Escherichia coli/genética , Genes Bacterianos , Secuencia de Aminoácidos , Secuencia de Bases , Transporte Biológico , Clonación Molecular/métodos , Genotipo , Datos de Secuencia Molecular , Plásmidos , Conformación Proteica , Mapeo Restrictivo , Homología de Secuencia de Ácido NucleicoRESUMEN
An antigen-binding fragment (Fab) from a murine monoclonal antibody (4-4-20) with high affinity for fluorescein was cocrystallized with ligand in polyethylene glycol (PEG) and 2-methyl-2,4-pentanediol (MPD) in forms suitable for X-ray analyses. In MPD the affinity of the intact antibody for fluorescein was 300 times lower than the value (3.4 x 10(10) M-1) obtained in aqueous buffers. This decreased affinity was manifested by the partial release of bound fluorescein when MPD was added to solutions of liganded Fab during crystallization trials. In PEG, the ligand remained firmly bound to the protein. The liganded Fab crystallized in the monoclinic space group P2(1) in PEG, with a = 58.6, b = 97.2, c = 44.5 A and beta = 95.2 degrees. In MPD the space group was triclinic P1, with a = 58.3, b = 43.4, c = 42.3 A, alpha = 83.9 degrees, beta = 87.6 degrees, and gamma = 84.5 degrees. X-ray diffraction data were collected for both forms to 2.5-A resolution. Surprisingly, the triclinic form of the liganed antifluorescyl Fab had the same space group, closely similar cell dimensions, and practically the same orientation in the unit cell as an unliganded Fab (BV04-01) with activity against single-stranded DNA.
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Anticuerpos Monoclonales/análisis , Glicoles , Fragmentos Fab de Inmunoglobulinas/análisis , Polietilenglicoles , Animales , Cristalografía , Fluoresceína , Fluoresceínas , Polarización de Fluorescencia , Hidrólisis , Ligandos , Ratones , Ratones Endogámicos BALB C , SolventesRESUMEN
Twenty-nine patients with gynaecological cancers who received over 400 mg of doxorubicin were monitored electrocardiographically to determine whether cardiac glycosides countered the adverse effects of high total doses of doxorubicin. Minor electrocardiographical changes were noted in five out of six patients who were not receiving a cardiac glycoside and four out of six who were receiving ouabain, and none of the 16 who were receiving digoxin. One other patient on digoxin stopped taking it and developed cardiomyopathy. One patient on ouabain also developed cardiomyopathy. So far nine patients on digoxin have received between 550 and 1000 mg/m2 of doxorubicin without ill effect. Cardiac glycosides are thought to prevent doxorubicin cardiomyopathy by competitively inhibiting doxorubicin at its receptor sites, but ouabain has a much shorter half life than doxorubicin and its metabolites and so is less effective than digoxin.