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1.
Clin Chim Acta ; 164(2): 189-200, 1987 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-3496179

RESUMO

Between-laboratory agreement for 6 specific protein assays was better in two surveys (total 8 specimens) in which a calibration material was provided than in the preceding five surveys (20 specimens) in a national external quality assessment scheme. CVs for immunoglobulins G, A and M (200 participants) and alpha 1-antitrypsin and complement components C3 and C4 (70 participants) were reduced from 18.3% (range 11.6-23.8%) to 10.7% (range 7.5-13.6%). This improvement was not due to changes in within-laboratory precision or in the concentrations of protein surveyed. Improvement was maintained in the following four surveys (3 normal and 5 pathological sera) without calibration material for immunoglobulins G and A and for alpha 1-antitrypsin. Agreement for immunoglobulin M, C3 and C4 returned to values close to the original CVs, but subsequently improved. The role of a common calibration material in improving between-laboratory agreement is discussed.


Assuntos
Proteínas Sanguíneas/análise , Laboratórios/normas , Complemento C3/análise , Complemento C4/análise , Humanos , Imunoglobulinas/análise , Controle de Qualidade , Padrões de Referência , alfa 1-Antitripsina/análise
2.
Clin Chim Acta ; 103(2): 219-28, 1980 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-7371200

RESUMO

A high resolution two-dimensional electrophoresis technique (Iso-Dalt) has been employed to characterise the protein components of freshly drawn human serum and various human- and animal-based quality control sera. This technique allows a direct comparison to be made between the protein components of different materials. Similarities have been demonstrated between the protein components (protein matrix) of freshly drawn human serum and human-, equine- and bovine-based control sera, though some differences existed between sera from these three sources, mainly in the acidic high molecular weight quadrant and the lipoprotein and haptoglobin regions. The Iso-Dalt technique also revealed differences in the protein matrices of the various human-based quality control sera tested. Differences attributable to manufacturing technique were also discernible by inspection of the two-dimensional maps of the protein matrices. Although characterisation and comparison of protein components of the matrix of serum is difficult, the Iso-Dalt technique has proved a valuable tool in this characterisation and the subsequent assessment of the similarity of quality control sera to human serum. This type of information is valuable when considering the suitability of human- or animal-based sera for use in internal and external quality control procedures.


Assuntos
Eletroforese das Proteínas Sanguíneas , Sangue , Controle de Qualidade , Animais , Bovinos , Eletroforese em Gel de Poliacrilamida/métodos , Cavalos , Humanos , Peso Molecular
3.
Clin Chim Acta ; 187(1): 21-35, 1990 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-2317926

RESUMO

An external quality assessment survey of immunochemical assays of 9 proteins (immunoglobulins G, A and M, complement components C3 and C4, alpha1-antitrypsin, orosomucoid, haptoglobin and transferrin) in 5 European countries (Austria, France, Hungary, Italy and UK) showed inter-country differences in the mean values obtained. Reprocessing of the results using one of the two specimens distributed as a 'calibrant' effectively eliminated or reduced substantially these differences. Consideration of the methods used by participants confirmed previous indications from national surveys that the differences were due to lack of agreement among commercial calibrants. Such interlaboratory variations were also minimised by the 'calibration' in this survey. The role of European working calibration materials in ensuring interlaboratory agreement on an international basis is discussed.


Assuntos
Proteínas Sanguíneas/análise , Imunoensaio/normas , Calibragem/normas , Europa (Continente) , Humanos , Imunoensaio/estatística & dados numéricos , Variações Dependentes do Observador , Controle de Qualidade , Padrões de Referência
4.
Ann Clin Biochem ; 22 ( Pt 3): 273-82, 1985 May.
Artigo em Inglês | MEDLINE | ID: mdl-4026187

RESUMO

Four years' experience with external quality assessment of urinary pregnancy oestrogen and creatinine assays using a revised scheme design, incorporating frequent distributions, individualised reports and running scores based on variance index scores, is described. During this period there was a rapid and substantial improvement in interlaboratory agreement, which appears attributable in part to these improvements in scheme design. The derivation and use of a new index, the SDBIS (standard deviation of the bias index score), which assesses variability of bias, are described. Investigations showed that urine-based calibration materials could improve between-laboratory agreement; there were only minor differences in performance between method groups.


Assuntos
Estrogênios/urina , Análise de Variância , Creatinina/urina , Feminino , Humanos , Gravidez , Controle de Qualidade , Padrões de Referência , Reino Unido
5.
Ann Clin Biochem ; 23 ( Pt 1): 92-6, 1986 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-3767257

RESUMO

Hexokinase methods for serum glucose assay appeared to give slightly but consistently higher inter-laboratory coefficients of variation than all methods combined in the UK External Quality Assessment Scheme; their performance over a two-year period was therefore compared with that for three groups of glucose oxidase methods. This assessment showed no intrinsic inferiority in the hexokinase method. The greater variation may be due to the more heterogeneous group of instruments, particularly discrete analysers, on which the method is used. The Beckman Glucose Analyzer and Astra group (using a glucose oxidase method) showed the least inter-laboratory variability but also the lowest mean value. No comment is offered on the absolute accuracy of any of the methods.


Assuntos
Glicemia/análise , Hexoquinase , Autoanálise/instrumentação , Glucose Oxidase , Humanos , Especificidade por Substrato
6.
Ann Clin Biochem ; 16(5): 249-53, 1979 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-42341

RESUMO

A survey of [H+], Pco2, and Po2 analyses in 360 laboratories was conducted using three commercial control materials: two aqueous gas-equilibrated buffer solutions (General Diagnostics and IL) and one whole blood material (DADE). There was little difference in precision or accuracy between instruments, classified according to manufacturer into four groups, and materials for [H+] and Pco2, or in precision for Po2. There were, however, differences in accuracy between instrument groups for Po2 analysis on the aqueous materials, and in some cases the mean values lay outside the range assigned by the material manufacturers. The 35 instruments outside clinical chemistry departments yielded results similar to those of all participants. The relation between inter- and intra-laboratory precision was similar to that for many analytes, suggesting that neither these materials nor the state of these analyses is unsatisfactory. Aqueous materials should, however, be used with caution as accuracy controls for Po2.


Assuntos
Gasometria/instrumentação , Sangue , Concentração de Íons de Hidrogênio , Dióxido de Carbono/sangue , Química Clínica , Humanos , Oxigênio/sangue , Pressão Parcial , Controle de Qualidade
7.
Ann Clin Biochem ; 28 ( Pt 5): 467-73, 1991 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-1958049

RESUMO

Three surveys of total urinary protein quantitation have been carried out in 350 UK laboratories. The seven specimens comprised buffered saline or normal human urine with added human serum albumin or human serum, or urine from individuals with nephrotic syndrome. Principal method groups were: turbidimetry (57%), dye binding (25%) and biuret (15%). For all surveys, overall between-laboratory agreement was poor (CV 22.8% to 57.1%), with ranges of results from 24-fold (0.83-20 g/L) to 366-fold (0.05-18.3 g/L); there was no improvement with time. The most popular method (sulphosalicylic acid turbidimetry) consistently performed the worst, and performance of the direct biuret procedure was also unacceptable; both methods should be discontinued. There were no significant differences in performance between the other major method groups, and none can be specifically recommended. Within the individual calibrant groups, least variation was observed with human serum. A common calibrant for all participants yielded significantly better between-laboratory agreement for all methods except sulphosalicylic acid turbidimetry.


Assuntos
Proteinúria/urina , Reação de Biureto , Química Clínica/normas , Corantes , Humanos , Nefelometria e Turbidimetria , Síndrome Nefrótica/urina , Controle de Qualidade , Padrões de Referência , Reprodutibilidade dos Testes , Reino Unido
8.
Ann Clin Biochem ; 21 ( Pt 4): 246-53, 1984 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-6333201

RESUMO

Five surveys of immunoglobulin A, G and M assay have been carried out in 200 UK laboratories; assays of complement components C3 and C4 and alpha 1-antitrypsin (alpha 1-AT) by 70 laboratories were also included in the fourth and fifth surveys. Clarified liquid human serum was used for specimens, two pairs of specimens related by dilution being used in each survey. For immunoglobulins, no inter-method bias was noted although one calibrant gave significantly different mean values; nephelometry, as used by one method group (largely comprising Beckman ICS users), and radial immunodiffusion gave the best inter-laboratory agreement for IgA and IgM, while IgG showed little method dependence. Inter-laboratory precision was better for C4 than for C3 and alpha 1-AT, which indicates the importance of calibrant differences for the latter two; there were too few participants to allow reliable conclusions about methods to be drawn.


Assuntos
Proteínas Sanguíneas/análise , Coleta de Amostras Sanguíneas , Complemento C3/análise , Complemento C4/análise , Humanos , Imunoensaio/normas , Imunoglobulinas/análise , Controle de Qualidade , Reino Unido , alfa 1-Antitripsina/análise
9.
Ann Clin Biochem ; 23 ( Pt 5): 577-84, 1986 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-3767296

RESUMO

The design and results of a UK external quality assessment scheme for six enzymes are described, from 21 surveys over a period of 7 years. Improvements in interlaboratory agreement and the adoption of reliable methods are documented. The potential of enzyme calibration materials in further improving numerical concordance between laboratories using different assay conditions, including temperature, is demonstrated and discussed.


Assuntos
Enzimas/sangue , Laboratórios/normas , Humanos , Controle de Qualidade
10.
Ann Clin Biochem ; 16(5): 271-4, 1979 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-517986

RESUMO

The rise in alkaline phosphatase activity has been studied after reconstitution of 16 commercial preparations of lyophilised quality control material. The effects of storage temperature and analytical method on the rise in activity have also been studied, with a view to producing a reconstitution protocol suitable for recommendation to participants in external quality control surveys. Great differences were found in the magnitude of this rise in activity; these differences can be reduced to negligible levels if the material is mixed for 30 minutes at ambient temperature after reconstitution and then stored for not more than 4 hours at 4 degrees C before assay.


Assuntos
Fosfatase Alcalina/sangue , Preservação de Sangue , Liofilização , Humanos , Controle de Qualidade
11.
Ann Clin Biochem ; 25 ( Pt 5): 560-8, 1988 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-3232958

RESUMO

The establishment and first 7 years' operation of an external quality assessment scheme for clinical chemistry in the Middle East region are described. The scheme utilises specimens distributed previously in the UK, and the performance of participating laboratories is assessed relative to the UK consensus values, taking account of method. Variance Index scoring has been used to quantitate performance, and there has been an improvement in average scores during the operation of the scheme. There are currently 88 participants, though some laboratories which failed to return results regularly were removed from the scheme. The consensus values from the scheme itself have now been validated, and in future the scheme should operate independently.


Assuntos
Química Clínica , Laboratórios/normas , Análise Química do Sangue/métodos , Humanos , Oriente Médio , Controle de Qualidade , Arábia Saudita , Reino Unido
12.
Ann Clin Biochem ; 17(3): 148-52, 1980 May.
Artigo em Inglês | MEDLINE | ID: mdl-7406438

RESUMO

The electrophoretic procedure for high density lipoprotein cholesterol determination recently introduced by Corning Medical has been assessed. The results corrrelated well with those obtained by phosphotungstate/Mg precipitation and ultracentrifuge procedures, but the between-batch CV was 6% in the clinically important range below 1 mmol/l. The densitometer, which must be carefully aligned before use for this analysis, seemed sensitive to variations in the plates and patterns produced. The technique required that great care, especially with timing, and appeared expensive.


Assuntos
Colesterol/sangue , Lipoproteínas HDL/sangue , Precipitação Química , Densitometria , Eletroforese em Gel de Ágar/métodos , Humanos , Kit de Reagentes para Diagnóstico/normas , Ultracentrifugação
13.
Ann Clin Biochem ; 29 ( Pt 2): 176-83, 1992 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-1626922

RESUMO

Acid phosphatase has been prepared in an apparently pure state by affinity chromatography from human prostatic tissue. When dissolved in an acidic albumin solution, lyophilized and stored at -20 degrees C for up to 2 years, no time-dependent loss of catalytic activity was detectable in the reconstituted material. Accelerated degradation tests also predicted complete stability. A preliminary distribution of the lyophilized preparation to 143 laboratories confirmed its robustness and demonstrated its potential usefulness as a calibrant to unify the results of different methods of measuring acid phosphatase activity.


Assuntos
Fosfatase Ácida/isolamento & purificação , Próstata/enzimologia , Fosfatase Ácida/normas , Cromatografia de Afinidade/métodos , Humanos , Masculino , Proteínas/análise , Valores de Referência
14.
Ann Clin Biochem ; 30 ( Pt 3): 304-14, 1993 May.
Artigo em Inglês | MEDLINE | ID: mdl-8517614

RESUMO

Two lyophilized control sera were distributed through seven national external quality assessment schemes in six European countries--Belgium, Switzerland, France, The Netherlands, Sweden and the United Kingdom--participated in the study. The results for 17 routine analytes were obtained from almost 5000 laboratories for the two sera. The organizers of the schemes were asked to process the results according to a common outlier removal procedure, and submit method-related data if available. The two sera were also distributed through the external/internal scheme of The Netherlands, and the within-laboratory standard deviations calculated in this scheme have been used in a scaling procedure for the external mean values and between-laboratory standard deviations of the participating countries. The results show remarkable agreement in the national mean values for practically all analytes, but considerable differences in the between-laboratory variation. Data from comparable method groups was obtained for 12 analytes from Belgium, France, The Netherlands and the UK. Though revealing some specific differences between methods and countries, the method-related data are generally in agreement with the all-method data. In this study reference method values were only available for cholesterol. The high degree of agreement found suggests, however, that mutual recognition of all-method mean values in national schemes could be acceptable, especially for analytes for which reliable reference methods are not available. The major element of variation is between-laboratory rather than between-country.


Assuntos
Análise Química do Sangue/normas , Química Clínica/normas , Animais , Glicemia/análise , Proteínas Sanguíneas/análise , Bovinos , Colesterol/sangue , Eletrólitos/sangue , Europa (Continente) , Controle de Qualidade
15.
Br J Gen Pract ; 43(366): 10-4, 1993 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-8457356

RESUMO

The results of a quality assessment survey of the most commonly used dry chemistry instrument in primary care in Norway and the United Kingdom, the Reflotron (Boehringer), are reported including an evaluation of some of the operational characteristics of the Reflotron users. The primary care users in Norway taking part in the study comprised 95 occupational health care departments and 89 general practices. In the UK, primary care users taking part were 95 occupational health care departments and 37 general practices. In terms of both accuracy and precision evaluation of concentrations of bilirubin, cholesterol, gamma-glutamyl transferase, glucose, triglycerides, urea and uric acid by primary care users was similar in the two countries, and to that of 60 Norwegian laboratories. Examination of operational characteristics revealed a lack of effective quality control measures in both countries, and some differences in the pattern of usage between primary care users in Norway and the UK, especially in general practice. The result of Reflotron tests were ready before the patient left in a considerably higher proportion of general practices in the UK than in Norway. It is concluded that the Reflotron is suitable for primary care use, but good, routine quality of analysis must be ensured through collaboration between primary care users and clinical chemists.


Assuntos
Análise Química do Sangue/instrumentação , Kit de Reagentes para Diagnóstico , Estudos de Avaliação como Assunto , Medicina de Família e Comunidade , Humanos , Noruega , Serviços de Saúde do Trabalhador , Controle de Qualidade , Reino Unido
16.
J Environ Qual ; 32(4): 1436-44, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-12931900

RESUMO

Continued inputs of fertilizer and manure in excess of crop requirements have led to a build-up of soil phosphorus (P) levels and increased P runoff from agricultural soils. The objectives of this study were to determine the effects of two tillage practices (no-till and chisel plow) and a range of soil P levels on the concentration and loads of dissolved reactive phosphorus (DRP), algal-available phosphorus (AAP), and total phosphorus (TP) losses in runoff, and to evaluate the P loss immediately following tillage in the fall, and after six months, in the spring. Rain simulations were conducted on a Typic Argiudoll under a corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation. Elapsed time after tillage (fall vs. spring) was not related to any form of P in runoff. No-till runoff averaged 0.40 mg L(-1) and 0.05 kg ha(-1) DRP and chisel-plow plots averaged 0.24 mg L(-1) and 0.02 kg ha(-1) DRP concentration and loads, respectively. The relationship between DRP and Bray P1 extraction values was approximated by a logistic function (S-shaped curve) for no-till plots and by a linear function for tilled plots. No significant differences were observed between tillage systems for TP and AAP in runoff. Bray P1 soil extraction values and sediment concentration in runoff were significantly related to the concentrations and amounts of AAP and TP in runoff. These results suggest that soil Bray P1 extraction values and runoff sediment concentration are two easily measured variables for adequate prediction of P runoff from agricultural fields.


Assuntos
Agricultura , Eutrofização , Fósforo/análise , Poluentes do Solo/análise , Movimentos da Água , Poluentes da Água/análise , Monitoramento Ambiental , Eucariotos , Fertilizantes , Esterco , Chuva , Estações do Ano , Glycine max , Zea mays
17.
J Environ Qual ; 33(4): 1535-44, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15254136

RESUMO

Excessive fertilization with organic and/or inorganic P amendments to cropland increases the potential risk of P loss to surface waters. The objective of this study was to evaluate the effects of soil test P level, source, and application method of P amendments on P in runoff following soybean [Glycine max (L.) Merr.]. The treatments consisted of two rates of swine (Sus scrofa domestica) liquid manure surface-applied and injected, 54 kg P ha(-1) triple superphosphate (TSP) surface-applied and incorporated, and a control with and without chisel-plowing. Rainfall simulations were conducted one month (1MO) and six months (6MO) after P amendment application for 2 yr. Soil injection of swine manure compared with surface application resulted in runoff P concentration decreases of 93, 82, and 94%, and P load decreases of 99, 94, and 99% for dissolved reactive phosphorus (DRP), total phosphorus (TP), and algal-available phosphorus (AAP), respectively. Incorporation of TSP also reduced P concentration in runoff significantly. Runoff P concentration and load from incorporated amendments did not differ from the control. Factors most strongly related to P in runoff from the incorporated treatments included Bray P1 soil extraction value for DRP concentration, and Bray P1 and sediment content in runoff for AAP and TP concentration and load. Injecting manure and chisel-plowing inorganic fertilizer reduced runoff P losses, decreased runoff volumes, and increased the time to runoff, thus minimizing the potential risk of surface water contamination. After incorporating the P amendments, controlling erosion is the main target to minimize TP losses from agricultural soils.


Assuntos
Fertilizantes , Esterco , Fósforo/análise , Poluentes do Solo/análise , Poluentes da Água/análise , Animais , Conservação dos Recursos Naturais , Monitoramento Ambiental , Chuva , Solo , Glycine max/crescimento & desenvolvimento , Suínos , Movimentos da Água
18.
Artigo em Inglês | MEDLINE | ID: mdl-2189209

RESUMO

During the last 2 years an external quality assessment (EQA) scheme has been developed for plasma cholesterol measurements made in primary care. The scheme, which is supported by the UK Department of Health and by the instrument manufacturers, now has over 300 participants, most of whom use the Boehringer Reflotron. Operators are mostly nurses, with little or no laboratory experience. To avoid matrix effects, fresh plasma specimens collected from normal volunteers and those attending a hospital lipid clinic are used. Three specimens, mostly with cholesterol concentrations in the range 5-9 mmol/L, are distributed every 2 months. The mean plasma cholesterol results show good agreement with those from 'reference' laboratories, and efforts are now being made to link these laboratories with the CDC-based reference system. The scheme uses a predominantly graphical presentation of results, with a greater element of interpretation by the organisers than is usually provided for laboratory-based participants. The distribution of results shows a higher proportion of outliers than in the UK national EQA scheme for laboratory cholesterol measurements. At present about 10% of participants in primary care obtain results which could be clinically misleading, and new approaches are needed in dealing with these 'poor performers'. This scheme could serve as a model for other assays in primary care. It illustrates the importance of training, quality assurance and education, and the need for laboratory staff to become more involved in this growing and important area of laboratory medicine.


Assuntos
Colesterol/sangue , Atenção Primária à Saúde , Controle de Qualidade , Química Clínica/educação , Química Clínica/instrumentação , Química Clínica/normas , Humanos , Laboratórios/normas
19.
Cent Afr J Med ; 40(12): 345-8, 1994 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-7882415

RESUMO

A pilot programme for assessing laboratory performance in clinical chemistry laboratories in Zimbabwe is described (ZEQAS). Twenty four laboratories providing patient care services participated. Eight lyphilised bovine sera were distributed over one year. Consensus values and the spread of interlaboratory agreement were calculated for each of 12 analytes and compared with results previously obtained in a large mature national EQA scheme in the UK (UK NEQAS). For all analytes except phosphate, the mean consensus value obtained in ZEQAS was between 94 and 108 pc of the UK target, although the spread of results in ZEQAS was generally two to threefold greater for individual analytes than in UK NEQAS. It is concluded the ZEQAS consensus values for the analytes surveyed provide a valid target against which individual laboratory performance can be assessed. The wide spread of results from individual laboratories suggests there is considerable scope for improving interlaboratory agreement. This is being addressed by the continuing programme, with increased interaction and production of local specimens.


Assuntos
Química Clínica , Laboratórios/normas , Garantia da Qualidade dos Cuidados de Saúde , Projetos Piloto , Zimbábue
20.
Ann Ist Super Sanita ; 31(1): 61-9, 1995.
Artigo em Inglês | MEDLINE | ID: mdl-8546376

RESUMO

The system of UK national external quality assessment schemes (NEQASs) has been developed over more than 20 years, using logical criteria for scheme design and operation, and their usefulness is supported by evidence of continuing improved performance. The UK approach has built on the enthusiasm and knowledge of individual experts working to provide a fully integrated system of EQASs to facilitate the provision of reliable patient care.


Assuntos
Química Clínica/normas , Garantia da Qualidade dos Cuidados de Saúde/organização & administração , Química Clínica/estatística & dados numéricos , Humanos , Avaliação de Programas e Projetos de Saúde , Garantia da Qualidade dos Cuidados de Saúde/normas , Garantia da Qualidade dos Cuidados de Saúde/estatística & dados numéricos , Controle de Qualidade , Reino Unido
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