Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 34
Filtrar
Más filtros

Banco de datos
Tipo del documento
Intervalo de año de publicación
1.
Bioorg Med Chem Lett ; 98: 129572, 2024 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-38043690

RESUMEN

Several series of diverse pyrazole-3-carboxamides functionalized with 4-methylamides, 4-methylcarboxylic acids and 4-methyltetrazoles were prepared from the corresponding 4-cyanomethylpyrazoles and investigated as Cannabinoid receptor 1 (CB1) antagonists and inverse agonists with the aim of making compounds with less CNS (Central Nervous System) mediated side-effects compared to rimonabant. The compounds were evaluated and optimized with respect to lipophilicity, solubility, CB1 potency, metabolism, distribution to brain and liver, effect on weight loss in diet-induced mice models. A few carboxylic acids and tetrazoles were selected as especially promising with the tetrazole TM38837 subsequently demonstrating impressive efficacy in various animal models of obesity, producing considerable weight loss and improvements on plasma markers of inflammation and glucose homeostasis, at doses apparently producing negligible brain exposure. TM38837 became the first peripherally restricted CB1 antagonist or inverse agonist to enter clinical trials supporting its lack of CNS effects and it is now believed that the non-CNS mediated efficacy is linked to high liver exposure. This opens opportunities to be explored in other indications such as nonalcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH). Note that this is a first-time disclosure of the structure of TM38837 and other structures appearing in literature are not connected with this program.


Asunto(s)
Cannabinoides , Agonismo Inverso de Drogas , Ratones , Animales , Agonistas de Receptores de Cannabinoides , Pirazoles/química , Cannabinoides/farmacología , Pérdida de Peso , Receptor Cannabinoide CB1 , Antagonistas de Receptores de Cannabinoides
2.
J Radiol Prot ; 43(1)2023 01 20.
Artículo en Inglés | MEDLINE | ID: mdl-36603219

RESUMEN

It is a core requirement of UK ionising radiations regulations 2017 (IRR17) compliance for radiation risk assessments and the investigation of accidental exposure scenarios that the magnitude of doses likely to be encountered are evaluated. A novel national audit was undertaken to investigate the variation in dose estimations for a range of foreseeable accidental exposure scenarios in nuclear medicine (NM). Participants were asked to estimate the levels of exposure in 15 foreseeable scenarios; covering whole-body and extremity exposures from external sources, internal exposure and exposures from skin (surface contamination and needle-stick injury) and eye contamination. Questions were intentionally simplified to reduce variation from assumptions made by the participants and to focus more on the underlying gross systematic variation. Twenty-seven centres participated. There was generally a very wide variation in the estimated exposures across all the categories of exposures, apart from internal exposure estimates. Whilst there was no ground truth for each individual question, the variation in results itself often exceeded the relevant threshold for classification and annual dose limits. The majority of variation was due to differences in methods, models and assumptions used by each participant. This audit raises questions around how IRR17 compliance can be universally demonstrated with such wide national variation. It evidences the need for a more standardised practice in NM radionuclide exposure estimates through national consensus guidelines or standards etc.


Asunto(s)
Medicina Nuclear , Exposición Profesional , Humanos , Dosis de Radiación , Exposición Profesional/análisis , Radioisótopos , Reino Unido
3.
Yeast ; 38(1): 117-126, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-33141945

RESUMEN

In many yeast species, the three genes at the centre of the galactose catabolism pathway, GAL1, GAL10 and GAL7, are neighbours in the genome and form a metabolic gene cluster. We report here that some yeast strains in the genus Torulaspora have much larger GAL clusters that include genes for melibiase (MEL1), galactose permease (GAL2), glucose transporter (HGT1), phosphoglucomutase (PGM1) and the transcription factor GAL4, in addition to GAL1, GAL10, and GAL7. Together, these eight genes encode almost all the steps in the pathway for catabolism of extracellular melibiose (a disaccharide of galactose and glucose). We show that a progenitor 5-gene cluster containing GAL 7-1-10-4-2 was likely present in the common ancestor of Torulaspora and Zygotorulaspora. It added PGM1 and MEL1 in the ancestor of most Torulaspora species. It underwent further expansion in the T. pretoriensis clade, involving the fusion of three progenitor clusters in tandem and the gain of HGT1. These giant GAL clusters are highly polymorphic in structure, and subject to horizontal transfers, pseudogenization and gene losses. We identify recent horizontal transfers of complete GAL clusters from T. franciscae into one strain of T. delbrueckii, and from a relative of T. maleeae into one strain of T. globosa. The variability and dynamic evolution of GAL clusters in Torulaspora indicates that there is strong natural selection on the GAL pathway in this genus.


Asunto(s)
Galactosa/metabolismo , Genes Fúngicos , Melibiosa/metabolismo , Redes y Vías Metabólicas/genética , Familia de Multigenes , Torulaspora/genética , Torulaspora/metabolismo
4.
J Neuroophthalmol ; 37(4): 414-417, 2017 12.
Artículo en Inglés | MEDLINE | ID: mdl-28742638

RESUMEN

We report the histopathological and ultrastructural tissue analysis of extraocular muscle (EOM) obtained from a patient with seronegative myasthenia gravis (MG) with treatment-resistant ophthalmoplegia for 3.5 years. The EOM demonstrated predominantly myopathic features and ultrastructural evidence of mitochondrial dysfunction, but the most striking features were increased endomysial collagen and adipocyte replacement of muscle fibers. By contrast, control EOM from a patient undergoing strabismus surgery for a sensory exotropia in a nonseeing eye and a similar duration of deviation, showed normal muscle histology. Although the histopathological and ultrastructural findings largely resemble those of limb muscle in MG, the abundant endomysial collagen may be nonspecific and secondary to poor force generation as a result of chronic ophthalmoplegia.


Asunto(s)
Resistencia a Medicamentos , Inmunosupresores/uso terapéutico , Miastenia Gravis/complicaciones , Músculos Oculomotores/ultraestructura , Oftalmoplejía/etiología , Biopsia , Femenino , Humanos , Microscopía Electrónica de Transmisión , Persona de Mediana Edad , Miastenia Gravis/diagnóstico , Miastenia Gravis/tratamiento farmacológico , Oftalmoplejía/diagnóstico , Oftalmoplejía/tratamiento farmacológico
5.
Angew Chem Int Ed Engl ; 54(7): 2174-8, 2015 Feb 09.
Artículo en Inglés | MEDLINE | ID: mdl-25476587

RESUMEN

A single aptamer bioreceptor layer was formed using a common streptavidin-biotin immobilization strategy and employed for 100-365 bind/release cycles. Chemically induced aptamer unfolding and release of its bound target was accomplished using alkaline solutions with high salt concentrations or deionized (DI) water. The use of DI water scavenged from the ambient atmosphere represents a first step towards maintenance-free biosensors that do not require the storage of liquid reagents. The aptamer binding affinity was determined by surface plasmon resonance and found to be almost constant over 100-365 bind/release cycles with a variation of less than 5% relative standard deviation. This reversible operation of biosensors based on immobilized aptamers without storage of liquid reagents introduces a conceptually new perspective in biosensing. Such new biosensing capability will be important for distributed sensor networks, sensors in resource-limited settings, and wearable sensor applications.


Asunto(s)
Aptámeros de Nucleótidos/química , Biotina/química , Estreptavidina/química , Resonancia por Plasmón de Superficie , Trombina/análisis , Ácidos Nucleicos Inmovilizados/química , Resonancia por Plasmón de Superficie/métodos
6.
Bioorg Med Chem Lett ; 20(2): 453-7, 2010 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-20015647

RESUMEN

A series of amides, amidines and amidoximes have been made from the corresponding nitrile compounds, to provide potent antagonists and inverse agonists for the CB1 receptor with considerably lower lipophiliciy, higher polar surface area and improved plasma/brain ratios compared to the centrally acting rimonabant. Extensive investigations of ADME and in vivo pharmacological properties led to selection of the amide series and specifically the 4-(4-fluorophenyl)piperidin-4-ol derivative D4. A clear improvement in the peripheral profile over rimonabant was seen, although some contribution of central effect on the pronounced weight reduction in obese mice cannot be ruled out.


Asunto(s)
Amidas/química , Fármacos Antiobesidad/química , Barrera Hematoencefálica/metabolismo , Piperidinas/química , Pirazoles/química , Receptor Cannabinoide CB1/antagonistas & inhibidores , Amidas/síntesis química , Amidas/farmacología , Animales , Fármacos Antiobesidad/síntesis química , Fármacos Antiobesidad/farmacocinética , Peso Corporal , Agonismo Inverso de Drogas , Ratones , Obesidad/tratamiento farmacológico , Piperidinas/síntesis química , Piperidinas/farmacología , Unión Proteica , Pirazoles/síntesis química , Pirazoles/farmacología , Ratas , Receptor Cannabinoide CB1/metabolismo , Rimonabant , Relación Estructura-Actividad
7.
Anal Chem ; 81(24): 9948-54, 2009 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-19916520

RESUMEN

Enabling trace chemical detection equipment utilized in the field to transduce a biodetection assay would be advantageous from a logistics, training, and maintenance standpoint. Described herein is an assay design that uses an unmodified, commercial off-the-shelf (COTS) ion trap mobility spectrometer to analyze an immunomagnetic enzyme-linked immunosorbant assay (ELISA). The assay, which uses undetectable enzymatic substrates and ELISA-generated detectable products, was optimized to quantitatively report the amount of target in the sample. Optimization of this ELISA design retained the assay specificity and detection limit (approximately 10(3) E. coli per assay) while decreasing the number of user steps and reducing the assay time to 10 min (>9-fold decrease as compared to past studies). Also discussed are previously undescribed, independent substrate/enzyme/product combinations used in the immunomagnetic ELISA. These discoveries allow for the possibility of a quantitative, multiplexed, 10-min assay that is analyzed by the ion trap mobility spectrometer trace chemical detector.


Asunto(s)
Ensayo de Inmunoadsorción Enzimática/métodos , Espectrometría de Masas/métodos , Fosfatasa Alcalina/química , Fosfatasa Alcalina/metabolismo , Galactosidasas/química , Galactosidasas/metabolismo , Galactósidos/química , Glucuronidasa/química , Glucuronidasa/metabolismo , Hidroxiquinolinas/química , Nitrofenoles/química , Fosfato de Piridoxal/química
9.
Nucl Med Commun ; 40(2): 136-144, 2019 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-30650067

RESUMEN

INTRODUCTION: This audit investigated hepatobiliary function imaging in UK hospitals, reviewing protocol differences in acquisition and processing parameters and the effect on calculated gallbladder ejection fraction (GBEF). PARTICIPANTS AND METHODS: Two dynamic data sets were available: one continuous dynamic data set, and the other with a 5-min break to administer the fatty stimulus. Participants used a set of 12 anonymized patient data sets most similar to their standard protocol calculating GBEF using their routine method. RESULTS: Fifty-two UK centres responded. Across all centres for all data sets, there was large variability in GBEF quoted, mostly owing to variations in the calculation method, motion correction and imaging type/times. The largest contributor to GBEF variation was time acquired after stimulus which varied from 20 to 70 min. Only 48.1% centres acquired for 60 min after stimulus, which is the acquisition time stated in normal range references. Overall, 13.5% participating centres administered fatty stimuli that fell below the recommended 10 g. Widespread variations were found in GBEF normal ranges and fatty stimulus administration. Motion correction has a large effect on GBEF; in one data set, motion correction alone changed GBEF from 44 to 9%, but 25% of the participants stated motion correction was not used. CONCLUSION: The authors proposed gold standard is fat content of the stimulus should be at least 10 g; and images should be acquired for 60 min after stimulus. If GBEF is quoted, motion correction should be used, and if compared with a normal range, the stimulus used must fit with the reference.


Asunto(s)
Sistema Biliar/diagnóstico por imagen , Hígado/diagnóstico por imagen , Auditoría Médica , Cintigrafía/normas , Programas Informáticos , Sistema Biliar/fisiología , Humanos , Hígado/fisiología , Reino Unido
10.
J Hand Surg Eur Vol ; 43(8): 832-835, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-29558848

RESUMEN

Nail varnish is commonly removed from fingernails prior to surgical procedures. We report the results of a randomized controlled trial comparing the microbial counts in hands with and without nail varnish applied, following surgical skin preparation. Forty-three patients were randomized; three patients were lost to follow-up. Each patient had one hand painted with nail varnish and had both hands tested 1 week later. There was no significant difference in terms of positive microbial growth between the nail plates or hyponichia with or without nail varnish applied. Our results demonstrate that the presence of nail varnish does not have an effect on the microbial counts of hands following surgical skin preparation. LEVEL OF EVIDENCE: I.


Asunto(s)
Recuento de Colonia Microbiana , Cosméticos , Desinfección de las Manos , Mano/microbiología , Uñas/microbiología , Adulto , Anciano , Anciano de 80 o más Años , Bacterias/aislamiento & purificación , Humanos , Persona de Mediana Edad , Cuidados Preoperatorios , Infección de la Herida Quirúrgica/prevención & control
11.
Genome Announc ; 6(25)2018 Jun 21.
Artículo en Inglés | MEDLINE | ID: mdl-29930059

RESUMEN

Metschnikowia strain UCD127 was isolated from soil in Ireland and sequenced. It is a highly heterozygous diploid strain with 385,000 single nucleotide polymorphisms (SNPs). Its ribosomal DNA has the highest similarity to that of M. chrysoperlae, but its ACT1 and TEF1 loci and mitochondrial genome show affinity to those of M. fructicola, whose genome is significantly larger.

12.
J AAPOS ; 11(2): 125-30, 2007 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-17306996

RESUMEN

BACKGROUND: Most studies of infantile esotropia concern patients diagnosed in infancy and treated throughout childhood. This prospective study addresses changes in the functional binocular status of older children and adults with previously untreated infantile esotropia, following late surgical realignment. SUBJECTS AND METHODS: Seventeen patients aged 8 years or more with a history of untreated esotropia occurring within the first 6 months of life were included in this study. All had monocular optokinetic asymmetry, a visual acuity of 20/30 or better in the worse eye, and binocular function assesment preoperatively and postoperatively. All were surgically aligned within 8(Delta) of orthotropia. None had neurologic disease. RESULTS: Preoperatively, all 17 patients demonstrated a monocular response to Bagolini lenses, while postoperatively 15 (88%) of the 17 demonstrated binocular function with Bagolini lenses (in that they could constantly perceive the major part of both arms of the X generated by the Bagolini lenses) and 13/17 (76%) demonstrated an increase in the binocular field. All 17 had no sensory fusion, either preoperatively or postoperatively, when tested with the Worth 4-Dot test or synoptophore, and no stereopsis with the Titmus stereo test. CONCLUSIONS: Older children and adults with previously untreated infantile esotropia derive some functional benefits following late surgical realignment. The degree of binocular function may be lower than that achieved in patients aligned before 24 months of age.


Asunto(s)
Esotropía/cirugía , Visión Binocular/fisiología , Adolescente , Adulto , Esotropía/fisiopatología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Músculos Oculomotores/fisiopatología , Músculos Oculomotores/cirugía , Procedimientos Quirúrgicos Oftalmológicos , Estudios Prospectivos , Agudeza Visual
13.
Nucl Med Commun ; 38(7): 608-616, 2017 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-28452796

RESUMEN

AIM: A national audit of quantitative thyroid uptake imaging was conducted by the Nuclear Medicine Software Quality Group of the Institute of Physics and Engineering in Medicine in 2014/2015. The aims of the audit were to measure and assess the variability in thyroid uptake results across the UK and to compare local protocols with British Nuclear Medicine Society (BNMS) guidelines. PARTICIPANTS AND METHODS: Participants were invited through a combination of emails on a public mailbase and targeted invitations from regional co-ordinators. All participants were given a set of images from which to calculate quantitative measures and a spreadsheet for capturing results. The image data consisted of two sets of 10 anterior thyroid images, half of which were acquired after administration of Tc-pertechnetate and the other half after administration of I-iodide. Images of the administration syringes or thyroid phantoms were also included. RESULTS: In total, 54 participants responded to the audit. The median number of scans conducted per year was 50. A majority of centres had at least one noncompliance in comparison with BNMS guidelines. Of most concern was the widespread lack of injection-site imaging. Quantitative results showed that both intersite and intrasite variability were low for the Tc dataset. The coefficient of quartile deviation was between 0.03 and 0.13 for measurements of overall percentage uptake. Although the number of returns for the I dataset was smaller, the level of variability between participants was greater (the coefficient of quartile deviation was between 0.17 and 0.25). CONCLUSION: A UK-wide audit showed that thyroid uptake imaging is still a common test in the UK. It was found that most centres do not adhere to all aspects of the BNMS practice guidelines but that quantitative results are reasonably consistent for Tc-based scans.


Asunto(s)
Auditoría Médica , Cintigrafía , Glándula Tiroides/diagnóstico por imagen , Glándula Tiroides/metabolismo , Transporte Biológico , Humanos , Cintigrafía/normas , Reino Unido
14.
Org Lett ; 8(10): 2103-6, 2006 May 11.
Artículo en Inglés | MEDLINE | ID: mdl-16671792

RESUMEN

[reaction: see text] Pyrrolidine-2,4-diones (1) are naturally occurring analogues of amino acids. We herein present a facile synthesis of N-acylated, O-alkylated pyrrolin-2-ones (2) in high yield and excellent enantiopurity. Molecular mechanics calculations suggest that the resulting dipeptide analogues adopt a linear, extended conformation.


Asunto(s)
Dipéptidos/síntesis química , Pirroles/química , Pirroles/síntesis química , Pirrolidinonas/síntesis química , Aminoácidos/química , Dipéptidos/química , Conformación Molecular , Estructura Molecular , Pirrolidinonas/química , Termodinámica
15.
Nucl Med Commun ; 37(1): 79-86, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-26465802

RESUMEN

OBJECTIVES: Glomerular filtration rate can be measured as the plasma clearance (CL) of a glomerular filtration rate marker despite body fluid disturbances using numerous, prolonged time samples. We desire a simplified technique without compromised accuracy and precision. MATERIALS AND METHODS: We compared CL values derived from two plasma concentration curve area methods - (a) biexponential fitting [CL (E2)] and (b) Tikhonov adaptively regularized gamma variate fitting [CL (Tk-GV)] - for 4 versus 8 h time samplings from 412 Tc-DTPA studies in 142 patients, mostly paediatric patients, with suspected fluid disturbances. RESULTS: CL (Tk-GV) from four samples/4 h and from nine samples/8 h, both accurately and precisely agreed with the standard, which was taken to be nine samples/8 h CL from (noncompartmental) numerical integration [CL (NI)]. The E2 method, four samples/4 h, and nine samples/8 h median CL values significantly overestimated the CL (NI) values by 4.9 and 3.8%, respectively. CONCLUSION: Compared with the standard, CL (E2) from four samples/4 h and from nine samples/8 h proved to be the most inaccurate and imprecise method examined, and can be replaced by better methods for calculating CL. The CL (Tk-GV) can be used to reduce sampling time in half from 8 to 4 h and from nine to four samples for a precise and accurate, yet more easily tolerated and simplified test.


Asunto(s)
Pentetato de Tecnecio Tc 99m/sangre , Pentetato de Tecnecio Tc 99m/farmacocinética , Adolescente , Adulto , Niño , Preescolar , Femenino , Tasa de Filtración Glomerular , Humanos , Lactante , Masculino , Tasa de Depuración Metabólica , Persona de Mediana Edad , Estudios Retrospectivos , Factores de Tiempo , Adulto Joven
16.
Dis Aquat Organ ; 63(2-3): 151-60, 2005 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-15819430

RESUMEN

The relative efficacies of 1 commercial and 5 experimental vaccines for bacterial kidney disease (BKD) were compared through a cohabitation waterborne challenge. Groups of juvenile chinook salmon Oncorhynchus tshawytscha were vaccinated with one of the following: (1) killed Renibacterium salmoninarum ATCC 33209 (Rs 33209) cells; (2) killed Rs 33209 cells which had been heated to 37 degrees C for 48 h, a process that destroys the p57 protein; (3) killed R. salmoninarum MT239 (Rs MT239) cells; (4) heated Rs MT239 cells; (5) a recombinant version of the p57 protein (r-p57) emulsified in Freund's incomplete adjuvant (FIA); (6) the commercial BKD vaccine Renogen; (7) phosphate-buffered saline (PBS) emulsified with an equal volume of FIA; or (8) PBS alone. Following injection, each fish was marked with a subcutaneous fluorescent latex tag denoting its treatment group and the vaccinated fish were combined into sham and disease challenge tanks. Two weeks after these fish were vaccinated, separate groups of fish were injected with either PBS or live R. salmoninarum GL64 and were placed inside coated-wire mesh cylinders (liveboxes) in the sham and disease challenge tanks, respectively. Mortalities in both tanks were recorded for 285 d. Any mortalities among the livebox fish were replaced with an appropriate cohort (infected with R. salmoninarum or healthy) fish. None of the bacterins evaluated in this study induced protective immunity against the R. salmoninarum shed from the infected livebox fish. The percentage survival within the test groups in the R. salmoninarum challenge tank ranged from 59% (heated Rs MT239 bacterin) to 81% (PBS emulsified with FIA). There were no differences in the percentage survival among the PBS-, PBS/FIA-, r-p57- and Renogen-injected groups. There also were no differences in survival among the bacterin groups, regardless of whether the bacterial cells had been heated or left untreated prior to injection.


Asunto(s)
Infecciones por Actinomycetales/veterinaria , Vacunas Bacterianas/inmunología , Enfermedades de los Peces/microbiología , Enfermedades de los Peces/prevención & control , Enfermedades Renales/veterinaria , Micrococcaceae/inmunología , Salmón , Infecciones por Actinomycetales/prevención & control , Animales , Acuicultura , Proteínas Bacterianas/genética , Proteínas Bacterianas/inmunología , Técnicas de Transferencia de Gen/veterinaria , Calor , Enfermedades Renales/microbiología , Enfermedades Renales/prevención & control , Plásmidos/genética , Wisconsin
17.
Middle East Afr J Ophthalmol ; 22(3): 312-9, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26180469

RESUMEN

Strabismus caused by ocular or orbital trauma can be the result of localized acute soft tissue swelling or may follow orbital fractures, partial or complete loss of extraocular muscle (EOM) and/or cranial nerve function, or damage to surrounding tissues causing mechanical restriction. The strabismus is frequently incomitant and can be difficult, if not impossible to completely correct. The resulting diplopia can affect the individual's ability to function at work, in sports and in common tasks of daily living like driving. The preoperative evaluation should include an assessment of the degree of limitation, muscle function and the condition of the surrounding tissue. In most cases, high resolution computed tomography and/or surface coil dynamic magnetic resonance imaging are required to determine the extent and nature of suspected bony or EOM injury, as well as muscle contractility. If the scan reveals an intact but paretic muscle or only minor muscle injury, surgical intervention is based on the degree of muscle recovery 6 months after the initial insult. If a rectus muscle has been lacerated, and the proximal stump is functional, retrieval should be attempted, either by a direct conjunctival approach if located anteriorly, or by an anterior medial orbitotomy if located deep in the orbit. If a damaged muscle cannot be found, recovered or repaired at any time, then muscle transposition should be considered. If multiple muscles are damaged or scar tissue is excessive, a tether procedure may be indicated. This paper will present an approach to some aspects of strabismus in this setting.


Asunto(s)
Lesiones Oculares/complicaciones , Músculos Oculomotores/lesiones , Órbita/lesiones , Fracturas Orbitales/complicaciones , Estrabismo/etiología , Diplopía/etiología , Diplopía/cirugía , Humanos , Imagen por Resonancia Magnética , Músculos Oculomotores/fisiopatología , Procedimientos Quirúrgicos Oftalmológicos , Fracturas Orbitales/cirugía , Estrabismo/fisiopatología , Estrabismo/cirugía , Tomografía Computarizada por Rayos X
18.
Nucl Med Commun ; 35(10): 1011-7, 2014 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-25029245

RESUMEN

INTRODUCTION: The purpose of this study was to investigate the optimized use of common uniformity indices [National Electrical Manufacturers' Association (NEMA) indices (differential and integral), Cox-Diffey and the coefficient of variation (CoV)]. METHODS: The indices were calculated for induced [localized two-dimensional (2D) Gaussian and gradient] artefacts added to three image sets (5, 10 and 15 million counts), each containing 25 extrinsic images, using Matlab. The intensity of the induced artefacts was varied between a 1 and 10% drop in pixel counts. The induced artefacts simulated photomultiplier tube [10 cm full width at half maximum (FWHM)], smaller focused artefacts (2.5 cm FWHM) and gradients artefacts. RESULTS: For five million count acquisitions, the Cox-Diffey, CoV and NEMA integral indices detected the 6% 2D Gaussian artefacts [10 cm full-width at half-maximum (FWHM)], whereas the NEMA differential index performed relatively poorly. NEMA differential and integral indices performed equally well at detecting smaller 2D Guassian (2.5 cm FWHM) artefacts. The 10% artefact was the minimum artefact detected by both indices for five million count acquisitions. The Cox-Diffey and CoV indices did not detect any artefacts for five million acquired counts. The CoV index performed best at detecting gradient artefacts at five million acquired counts. CONCLUSION: This work provides evidence that daily quality control can be acquired with as few as five million counts while maintaining the same ability to detect both chronic and acute nonuniformities compared with higher count acquisitions. A combination of the NEMA integral and the CoV indices gives the optimal selection of uniformity indices for detecting a range of artefact forms and intensities.


Asunto(s)
Cámaras gamma/normas , Algoritmos , Artefactos , Humanos , Distribución Normal , Control de Calidad , Reproducibilidad de los Resultados
19.
Nucl Med Commun ; 35(5): 511-21, 2014 May.
Artículo en Inglés | MEDLINE | ID: mdl-24448215

RESUMEN

INTRODUCTION: The Nuclear Medicine Software Quality Group of the Institute of Physics and Engineering in Medicine has conducted a multicentre, multivendor audit to evaluate the use of resolution recovery software from several manufacturers when applied to myocardial perfusion data with half the normal counts acquired under a variety of clinical protocols in a range of departments. The objective was to determine whether centres could obtain clinical results with half-count data processed with resolution recovery software that were equivalent to those obtained using their normal protocols. MATERIALS AND METHODS: Sixteen centres selected 50 routine myocardial perfusion studies each, from which the Nuclear Medicine Software Quality Group generated simulated half-count studies using Poisson resampling. These half-count studies were reconstructed using resolution recovery and the clinical reports compared with the original reports from the full-count data. A total of 769 patient studies were processed and compared. RESULTS: Eight centres found only a small number of clinically relevant discrepancies between the two reports, whereas eight had an unacceptably high number of discrepancies. There were no significant differences in acquisition parameters between the two groups, although centres finding a high number of discrepancies were more likely to perform both rest and stress scans on normal studies. CONCLUSION: Half of the participating centres could potentially make use of resolution recovery to reduce the administered activity for myocardial perfusion scans without changing their routine acquisition protocols. The other half could consider adjusting the reconstruction parameters used with their resolution recovery software if they wish to use reduced activity successfully.


Asunto(s)
Procesamiento de Imagen Asistido por Computador , Auditoría Médica , Imagen de Perfusión Miocárdica , Programas Informáticos , Humanos , Volumen Sistólico
20.
Nucl Med Commun ; 35(11): 1096-106, 2014 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-25144565

RESUMEN

INTRODUCTION: An audit was carried out into UK glomerular filtration rate (GFR) calculation. The results were compared with an identical 2001 audit. METHODS: Participants used their routine method to calculate GFR for 20 data sets (four plasma samples) in millilitres per minute and also the GFR normalized for body surface area. Some unsound data sets were included to analyse the applied quality control (QC) methods. Variability between centres was assessed for each data set, compared with the national median and a reference value calculated using the method recommended in the British Nuclear Medicine Society guidelines. The influence of the number of samples on variability was studied. Supplementary data were requested on workload and methodology. RESULTS: The 59 returns showed widespread standardization. The applied early exponential clearance correction was the main contributor to the observed variability. These corrections were applied by 97% of centres (50% - 2001) with 80% using the recommended averaged Brochner-Mortenson correction. Approximately 75% applied the recommended Haycock body surface area formula for adults (78% for children). The effect of the number of samples used was not significant. There was wide variability in the applied QC techniques, especially in terms of the use of the volume of distribution. CONCLUSION: The widespread adoption of the guidelines has harmonized national GFR calculation compared with the previous audit. Further standardization could further reduce variability. This audit has highlighted the need to address the national standardization of QC methods. Radionuclide techniques are confirmed as the preferred method for GFR measurement when an unequivocal result is required.


Asunto(s)
Auditoría Clínica , Tasa de Filtración Glomerular , Pruebas de Función Renal/métodos , Plasma/metabolismo , Adulto , Niño , Femenino , Humanos , Masculino , Persona de Mediana Edad , Guías de Práctica Clínica como Asunto , Control de Calidad , Reino Unido
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA