bluuebunny/crossref_metadata_2025 huggingface dataset:
Systemic Availability of Oral Slow-Release Morphine in Man
Authors: Moore R A , McQuay H J , Bullingham R E S , Baldwin D , Allen M C
Published: February 2014

In a within-patient crossover study on twelve patients we investigated plasma morphine concentrations for 48 hours after administration of intravenous morphine sulphate followed 24 hours later by oral MST Continus [MST]. Patients received either 10 mg i.v. morphine followed by 10 mg MST or 20 mg i.v. morphine followed by 2×10 mg MST tablets. Systemic clearance of morphine was low, being about 3 ml/min/kg after both intravenous and oral administration. The ratio of the areas under the concentration–time curve for MST relative to that for i.v. morphine was about 1:1 for 20 mg doses, but was significantly greater than 1:1 for 10 mg doses. The results suggest high oral systemic availability for morphine and low hepatic morphine metabolism.
A Direct Radioimmunoassay for the Determination of Adrenocorticotropic Hormone (ACTH) and a Clinical Evaluation
Authors: Marts C J , Koppeschaar H P F , Veeman W , Thijssen J H H
Published: February 2014

A direct radioimmunoassay for the determination of ACTH in a small volume of serum was developed using a commercially available antiserum and tracer. A single-stage radioimmunoassay with an incubation period of 4 days gave reliable and reproducible ACTH values. In the incubation medium 0·1% 2-mercaptoethanol was used as the antioxidant. During a 15-month period the assay has been used routinely in the laboratory.

The coefficient of variation was less than 10% in the physiological and pathological range. A normal range of 12 to 60 ng/L was found. The reliability of the assay is demonstrated by results obtained in patients with disorders of the pituitary-adrenal axis.
External Quality Assessment of Urinary Pregnancy Oestrogen Assay: Further Experience in the United Kingdom
Authors: Bullock David G , Wilde Colin E
Published: February 2014

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.
A Simple, Optimised and Rapid Assay for Urinary Free Catecholamines by HPLC with Electrochemical Detection
Authors: Davidson D F , Fitzpatrick J
Published: February 2014

A rapid method is described for the determination of urinary free catecholamines by HPLC with electrochemical detection. Optimised and equilibrium assay conditions are assessed for sample preparation, separation and detection. Catecholamine stability is maintained during the assay procedure by the addition of a combined reducing agent. Variability in recovery between aqueous standards and urine samples is minimised by dilution of samples with a concentrated Tris buffer solution. Ethyl acetate washing of an acid eluate is performed after and not before an alumina adsorption step in order to make the procedure as simple and rapid as possible.

The method is evaluated and has thus far identified two cases of phaeochromocytoma and one case of neuroblastoma.
Determination of Aluminium in Serum: Findings of an External Quality Assessment Scheme
Authors: Taylor Andrew , Starkey Bryan J , Walker Arthur W
Published: February 2014

The analytical performance of laboratories participating in the serum aluminium programme of the Guildford Trace Element Quality Assessment Scheme has been evaluated. The considerable disparity between reported results was not attributable to the nature of the samples distributed, nor to the standard aluminium solutions used in different laboratories. All laboratories used electrothermal atomic absorption spectrometry but sample preparation procedures and temperature programmes varied enormously. While some laboratories performed better than others in the scheme, and the standard of analysis appears to be improving with time, no laboratory showed consistent acceptable performance.
Radial Presentation of Results of Blood Acid-Base Analyses
Authors: Baron D N
Published: February 2014

Both students and clinical users find interpretation of blood acid-base numerical values to be difficult. A radial plot provides patterns which are easy to understand, and which can be applied to many groups of laboratory results.
High Electroendosmotic Agarose Electrophoresis and Nitrocellulose Immobilisation for the Detection of Oligoclonal Bands in Unconcentrated Cerebrospinal Fluid
Authors: Keir G , Chowhan M R , Thompson E J
Published: February 2014

A sensitive (1 μL of unconcentrated sample), specific (IgG Fc) and economical (10 p/test) method for the detection of oligoclonal bands in cerebrospinal fluid is presented. Using commonly available technology (agarose gel electrophoresis) and giving results within 6 h, the approach used here is a powerful tool in the investigation of immunoglobulin abnormalities in many biological fluids.
Continuous-Flow Assay for Urinary Oxalate Using Immobilised Oxalate Oxidase
Authors: Kasidas G P , Rose G Alan
Published: February 2014

A continuous-flow assay for measuring oxalate in urine is described. Covalently attached oxalate oxidase (EC 1.2.3.4) is used to oxidise the oxalate anion to carbon dioxide and hydrogen peroxide. The formed hydrogen peroxide is measured colorimetrically (A58n) with an established reaction using horseradish peroxidase (EC 1.11.17), 3-methyl-2-benzothiazolinone hydrazone (MBTH) and 3-dimethylaminobenzoic acid (DMAB). Ascorbate interference is eliminated by treating the urine sample with sodium nitrite prior to assaying. The assay is accurate (mean recovery of added oxalate in spiked urine sample is 93 ± 11%), sensitive (detection limit 1·0 μmol/L), reproducible (within-batch CV 3·5%; between-batch CV 5%) and relatively rapid (15 samples/h). This assay correlates well (R = 0·99) with another established enzymatic method (using oxalate decarboxylase).
The Relationship between Sex Steroids and Sex-Hormone-Binding Globulin in Plasma in Physiological and Pathological Conditions
Authors: Cunningham Sean K , Loughlin Therese , Culliton Marie , McKenna T Joseph
Published: February 2014

Physiological and many pathological changes in plasma sex-hormone-binding globulin (SHBG) levels have been attributed to the opposing effects of androgens which lower, and oestrogens which elevate, levels. We examined four clinical situations in which changes in SHBG levels may not be explained by sex steroid alterations. (1) Dexamethasone caused an increase in SHBG levels in hyperandrogenaemic hirsute women whether or not androgens were suppressed. (2) In male patients with untreated isolated gonadotrophin deficiency there was a highly significant correlation between SHBG levels and age, but there was no relationship between the levels of SHBG and those of plasma testosterone, androstenedione or DHEAS. (3) Two 46-XY siblings, phenotypic female subjects with complete androgen insensitivity, demonstrated a marked decline in SHBG levels between the ages of 9–13 and 12–16 years. (4) SHBG was suppressed in obese oligomenorrhoeic women while plasma concentrations of testosterone, androstenedione and oestradiol were normal and that of oestrone was elevated; however, the testosterone: SHBG ratio, an index of free testosterone, was elevated. These observations indicate that the decline in SHBG levels which normally occurs in men during the second decade of life is independent of androgen activity and is under the influence of as yet unidentified factors. Glucocorticoids in small doses increase SHBG levels independently of sex steroid alterations while elevated free testosterone concentration may contribute to suppression of SHBG in obesity.
Hormone Studies in a Case of Virilisation Due to Ovarian Tumour
Authors: Fleetwood J A , Watson M J , Wastell Hilary J , Weddell Ann
Published: February 2014

The investigation is described of a 62-year-old female patient who presented with severe virilisation; her plasma testosterone concentration was grossly elevated at 37–9 nmol/L. Measurement of plasma androstenedione, dehydroepiandrosterone (DHEA) and DHEA-sulphate, urinary 17-oxosteroids and urinary ‘free’ Cortisol suggested an ovarian source of androgens. An ultrasound scan indicated the presence of an ovarian mass which was removed and classified as a Sertoli—Leydig cell tumour (arrhenoblastoma) combined with a mucinous cystadenoma. Following operation plasma testosterone levels returned to normal.

The excessive pre-operative testosterone production appeared to have had little effect on the plasma level of SHBG, since levels remained similar before and after removal of the tumour. Serum LH and FSH levels were higher post-operatively.
An Extremely Simple and Fast Microlitre Method for the Determination of Total Carbon Dioxide in Biological Samples
Authors: Van Stekelenburg G J , Valk C , Van Wijngaarden-Penterman M J G
Published: February 2014

For those clinical laboratories equipped with a microprocessor-controlled gas analyser, an extremely simple method is described for the determination of the total carbon dioxide content in various biological fluids. Since this method needs only 20 μL of blood plasma or is less dependent on the original total carbon dioxide content, it is especially suited for paediatric purposes. With our procedure the time necessary for one determination equals the time for one capillary blood gas analysis.
A Simple and Rapid Nephelometric Procedure for Fibronectin
Authors: Cuigniez P H , Biesbrouck M , Van Hooren J
Published: February 2014

A nephelometric assay (Beckman ICS) for the measurement of plasma fibronectin using commercially available reagents (Boehringer) is described. The assay is simple, rapid and cheap and has a high degree of specificity. The within-run variation was between 4·3 and 7·8%. Only 30 μL of antiserum is used for one measurement, instead of 100 μL used with the turbidimetric method.
Direct Determination of Theophylline in Serum by Fluoroimmunoassay Using Highly Specific Antibodies
Authors: Hodgkinson A J , Sidki A M , Landon J , Rowell F J , Mahmod S M
Published: February 2014

Described is the development of a fluoroimmunoassay for theophylline using a fluorescein labelled derivative of theophylline as tracer and antibodies coupled to magnetisable solid-phase particles. Three approaches are described for the preparation of antibodies for theophylline, of which one produced highly specific, high titre antibodies. The fluoroimmunoassay using these antibodies required a 10 μL sample, reached equilibrium within 5 min, and the results correlated closely with those of an established enzymoimmunoassay method. Potentially interfering endogenous fluorophores from the serum sample were reliably removed at the separation step of the bound and free fractions. There was no significant cross-reactivity with all other structurally related compounds.
Direct Assay for Progesterone in Saliva: Comparison with a Direct Serum Assay
Authors: Webley G E , Edwards R
Published: February 2014

Direct assays have been described for the estimation of progesterone in serum and saliva. Both methods showed good inter-assay precision over a year, and the serum assay is now being used routinely in clinical laboratories. A highly significant correlation was obtained for progesterone concentrations in matched serum and saliva samples over a wide range of concentrations. The concentrations of progesterone in daily samples taken through the menstrual cycle fell within the range quoted in previous studies. The benefits of direct saliva measurement are described with reference to the long-term assessment of irregular cycles. Care in sample collection is necessary since contamination with agents such as oral cosmetics may result in overestimation of progesterone concentrations.
Evaluation of the Diagnostic Value of Serum Bile Acid in the Detection and Functional Assessment of Liver Diseases
Authors: Cravetto C , Molino G , Biondi A M , Cavanna A , Avagnina P , Frediani S
Published: February 2014

The diagnostic usefulness of fasting total serum bile acids (SBA/F) in the detection of liver diseases and assessment of different aspects of hepatic function alteration was evaluated in 61 healthy subjects and 186 patients with liver disease. The value of SBA/F was compared with other routine tests. In 49 healthy subjects and 92 patients, serum bile acids were also measured after the im administration of Ceruletide as a cholecystokinetic agent (SBA/C).

The diagnostic efficacy for the detection of disease states was better with aspartate-aminotransferase (EC 2.6.1.1) and alanine-aminotransferase (EC 2.6.1.2) than with SBA/F. When SBA/C was also determined the diagnostic efficacy was not substantially better than the SBA/F test.

In the assessment of hepatocellular necrosis SBA/F showed a higher rate of misclassification errors compared to alanine-aminotransferase (mean error 45% vs 17%), whereas SBA/F gave similar results with direct bilirubin and pseudocholinesterase (EC 3.1.1.8) in the evaluation of cholestasis (mean error 40% vs 41%) and impaired biosynthesis (mean error 39% vs 40%), respectively.

Serum bile acid determination did not show any significant diagnostic advantage with respect to the other routine liver tests.
Evaluation of a Time-Resolved Immunofluorometric Assay for Serum Thyroid Stimulating Hormone
Authors: Paterson N , Biggart E M , Chapman R S , Beastall G H
Published: February 2014

The LKB ‘Delfia™’ immunofluorometric assay for serum TSH has been evaluated. The assay is simple and rapid to perform and is capable of processing in excess of 100 specimens within a working day. The sensitivity of the assay is 0·05 mU/L, with a working range extending beyond 324 mU/L. The change in signal at each point over the standard curve approaches 1000-fold, significantly greater than that of a typical immunoradiometric assay.

Mean figures for intra-assay and inter-assay precision were 4·7% and 8·6% CV, respectively. Mean recovery of added TSH was 98·3%, and samples containing high levels of endogenous TSH diluted parallel to the standard curve. The method showed good correlation with an immunoradiometric assay for TSH. The reference ranges for clinically defined groups of subjects were euthyroid 0·47–3·84 mU/L ( n = 83); primary hypothyroidism 15 — >324 mU/L ( n = 28); thyrotoxicosis <0·05 mU/L ( n = 46).

It is concluded that the ‘Delfia’ assay offers the clinical biochemistry laboratory an attractive and reliable alternative to a sensitive immunoradiometric assay for serum TSH.
Regional Quality Assessment of pH and Blood Gas Analysers
Authors: Burnett David , Henfrey Richard D , Woods T F , Fyffe John A
Published: February 2014

The performance of 41 pH and blood gas analysers in 20 hospitals was assessed using commercially available blood gas ampoules provided by seven manufacturers. The stability of the material and the effect of ambient temperature on PO2 was assessed. The overall mean values were outside the manufacturers' assigned values on eight out of 64 values. Using IL413 analysers as a basis for comparison, significant differences were found for PCo2 on ABL1, Corning 168 and 178 analysers and for PO2 on ABL1 and 2 and Corning 178. No significant differences were found for pH. Poor performers were identified in terms of imprecision. Analysers within or associated with clinical biochemistry departments gave better performance than those outside the laboratory. The five analysers that provided insufficient data for inclusion in the study were all situated outside the laboratory. Analysers from different manufacturers performed equally well provided they were used regularly and in accordance with manufacturers' instructions.
Enhanced Luminescent Quantitation of Horseradish Peroxidase Conjugates: Application in an Enzyme Immunoassay for Digoxin
Authors: Coyle P M , Thorpe G H G , Kricka L J , Whitehead T P
Published: February 2014

A p-iodophenol-enhanced luminescent end-point has been incorporated into a commercially available heterogeneous competitive enzyme immunoassay for digoxin based on a horseradish peroxidase-digoxin conjugate. The luminescent end-point could be completed in less than 1 min and significantly reduced overall assay time. Results for the assay obtained using enhanced luminescence showed good agreement with those obtained using a colorimetric end-point (correlation coefficient 0·98). Both assays gave acceptable precision within the therapeutic range. The incubation time for the luminescent immunoassay was reduced to 15 min and still gave differentiation between sub-therapeutic, therapeutic and toxic levels of digoxin.
A More Sensitive and Less Time-Consuming Sandwich Enzyme Immunoassay for Insulin in Human Serum with Less Serum Interference
Authors: Ruan Ke-He , Hashida Seiichi , Yoshitake Shinji , Ishikawa Eiji , Wakisaka Osamu , Yamamoto Yoshitaka , Ichioka Takafumi , Nakajima Katsuyuki
Published: February 2014

This paper describes an improved sandwich enzyme immunoassay for insulin in human serum. The detection limit was significantly improved from 0·1 mU/L to 0·02 mU/L, by incubation with guinea-pig anti-insulin Fab′-peroxidase conjugate in the presence of normal guinea-pig F(ab′)2 to reduce the non-specific binding of the conjugate. The degree of serum interference was considerably reduced by coating polystyrene balls with acid-treated anti-insulin IgG and by incubating the polystyrene balls with serum samples at a lower temperature for a shorter time. The time for incubation with anti-insulin Fab′-peroxidase conjugate was also shortened. As a result, the volume of serum that could be used increased from 10 μl to 50 μl, and the time for immuno-reactions was reduced from 8 h to 4 h. Applicability of the present improvement to enzyme immunoassay of other antigens in human serum is discussed.
Thyroid Function Tests in Patients with Familial Dysalbuminaemic Hyperthyroxinaemia (FDH)
Authors: Stewart M Felicity , Ratcliffe Wendy A , Roberts Ian
Published: February 2014

Two patients with familial dysalbuminaemic hyperthyroxinaemia (FDH) are described in whom the albumin variant resulted in raised total T4 levels, and artefactually raised free T4 using a ‘single-step’ technique employing an analogue of T4 as tracer. The first patient was clinically euthyroid and presented with relapse of schizophrenia and abnormal thyroid function tests (total T4 336 nmol/L, total T3 4·2 nmol/L, TSH 1·8 mU/L, free T4 73 pmol/L). These results led to diagnostic confusion and the patient was treated with a short course of anti-thyroid drugs. The second patient had signs and symptoms of thyrotoxicosis at her first visit but was clinically euthyroid 5 months later when she was 10 weeks pregnant. Thyroid function tests were total T4 259 nmol/L, total T3 3·6 nmol/L, TSH 3·8 mU/L, free T4 46 pmol/L. Further studies showed both patients to be biochemically euthyroid. A variant albumin was confirmed in both patients by a screening test for FDH and by reverse-flow electrophoresis. Family studies on 10 relatives of the first patient identified eight with FDH. A simple screening procedure for the indentification of FDH is described and the use of laboratory tests in suspected cases is discussed.
Glycosylated Haemoglobin: Comparison of Five Different Methods, Including Measurement on Capillary Blood Samples
Authors: Moore J C , Bown E , Outlaw M C , Jelfs R , Holman R R , Turner R C
Published: February 2014

Glycosylated haemoglobin was measured in venous blood samples and in blood collected in ‘Unistep’ bottles by isoelectric focusing (IEF), as the reference method, and by electroendosmosis (EEO), the thiobarbituric acid method (TBA), ion-exchange chromatography (IEC) and affinity chromatography (AC). Isoelectric focusing, electroendosmosis and thiobarbituric acid gave similar results. Affinity chromatography gave lower results than isoelectric focusing for normal values but similar results for diabetics. Ion-exchange chromatography gave 24% lower results than isoelectric focusing across the range. Using Unistep collected blood samples and comparing multiple samples from the same patient, electroendosmosis gave the best results (coefficient of variation 4%) and thiobarbituric acid gave slightly less good precision that other methods. Re-use of affinity chromatography columns gave less good precision. Collection of blood samples into a Unistep bottle gave similar results to venous sample results. Storage of venous capillary blood samples in Unistep bottles over 1 week at 21°C gave similar results to immediate assay. Electroendosmosis of blood samples in Unistep bottles gave stable results over 2 weeks. Home collection by a patient of a capillary blood sample into a Unistep bottle allows glycosylated haemoglobin results to be available when seen in the clinic.
Acceptance of Values Assigned to Serum-Based Calibration Materials
Authors: Burnett D , Woods T F , Jennings R D
Published: February 2014

A questionnaire sent to laboratories in the UK and Ireland elicited information on acceptance or otherwise of values assigned to serum-based calibration materials for 14 analytes. Overall, 33% of assigned values were changed by users. The reasons for change, together with the degree of magnitude and direction of change, were studied for each analyte. Unidirectional changes made to assigned values were related to particular batches and manufacturers. Detailed information is presented for protein (Beckman RIIC Ltd.) on Astras, and sodium, bicarbonate and bilirubin on SMACs and SMAs (Technicon Instrument Co. Ltd.)
Changes in Sample Isoferritin Composition as a Possible Cause of Dilutional Discrepancies in Ferritin 2-Site Immunoradiometric Assay Results
Authors: Ryall Richard G , Rumpff John
Published: February 2014

The effect of changes in sample isoferritin composition on the behaviour of ferritin 2-site immunoradiometric assays was investigated using a computer model and experimental studies. Modelling studies predicted that under conditions where a sample has a different isoferritin composition from the assay standards, progressively higher values will be generated for the apparent ferritin content of the sample when it is analysed at increasing dilutions. In addition, the assay results will underestimate the actual ferritin content of such samples at all dilutions. Dilutional discrepancies in assay results and underestimation of sample ferritin concentrations were found in practical assays when synthetic samples with demonstrably different isoferritin profiles were analysed. Differences in isoferritin composition between assay standards and assayed samples may therefore be a cause of dilutional discrepancies in some results from ferritin 2-site immunoradiometric assays.
Glycosylated Plasma Protein Measurement by a Semi-Automated Method
Authors: Moore J C , Outlaw M C , Barnes A J , Turner R C
Published: February 2014

A semi-automated method for determination of glycosylation of plasma proteins using the thiobarbituric acid method is described. Plasma samples (100 μL) and a plasma pool used as a secondary standard were incubated in 0·3 M oxalic acid at 100°C for exactly 2 h. The hydroxymethyl furfural released and the total protein were measured concurrently on a Technicon AAII Autoanalyzer. Addition of 10 or 20 mmol glucose to plasma samples caused a minimal increase in the measured glycosylated protein. Within-batch and between-batch coefficients of variation were 3·1% and 4·9% respectively. The mean glycosylated protein levels for 52 normals and 48 maturity-onset diabetics were (±1SD) 0·96±0·13 and 1·75±0·32 nmol HMF/mg protein/2 h incubation.
Comparison of the Analytical Characteristics of Ten Urinary hCG Tests for Early Pregnancy Diagnosis
Authors: Thomas C M G , Segers M F G , Leloux A M , Houx P C W
Published: February 2014

A comparison of assay design, sensitivity and specificity is given for 10 urinary human chorionic gonadotrophin (hCG) test kits for early pregnancy diagnosis. One slide test applies a polyclonal anti-hCG serum, while nine, more recently developed, tube and slide tests use one or more monoclonal antibodies toward intact hCG or its free subunits. Colour development for five immunoenzymetric (IEMA) ‘sandwich’ assays, or (haem/latex) agglutination (HA, LA)-inhibition (HAI, LAI) for the other systems provide assay sensitivities from 1000–50 IU/L within 3–120 min. The ‘best’ slide-(i.e., LA, LAI), haem-(i.e., HA, HAI) and IEMA-tests detect respectively 500, 75 and 50 IU/L within 2·5, 120 and 3 min. Assay specificities (i.e., as false-positive and false-negative test results) are studied using intact hCG, hLH and their free α- and β-subunits. The presented assays are improved, perform more sensitively at shorter reaction times with increased specificity, and may, therefore, establish pregnancy at an earlier stage with greater reliability.
On the Assessment of the in Vitro Biopotency and Site(s) of Action of Drugs Affecting Adrenal Steroidogenesis
Authors: Lambert A , Frost J , Mitchell R , Robertson W R
Published: February 2014

Dispersed guinea-pig adrenal cells have been employed in the in vitro estimation of the biological potency and sites of action of drugs acting against the adrenal. The effect of 12 drugs on cortisol secretion from cells stimulated with adrenocorticotrophin (ACTH, 50 ng/L, a 95% saturating dose) has been tested. All the drugs depressed cortisol output in a dose-related fashion. The concentration of drug which inhibited secretion by 50% was (μmol/L, mean±SEM): etomidate 0·1±0·002; epostane 0·44±0·02: 17-ketotrilostane 0·55±0·04: trilostane 1·3±0·1: metyrapone 3·5±0·6: cyproterone acetate 4·6±0·2: megestrol acetate 11±2: danazol 22±2: aminoglutethimide 41±5: stanozolol 50±4: thiopentone 160±18: propofol 170±18.

The sites of the anti-steroidogenic effect of seven of these drugs have also been established using a method based upon the sequential stimulation by the exogenous precursor steroids of the various steps leading to the biosynthesis of cortisol by adrenal cells. Propofol acts between ACTH binding and pregnenolone production, trilostane, megestrol acetate and cyproterone acetate are 3β-hydroxysteroid dehydrogenase inhibitors whereas metyrapone, etomidate and thiopentone act at 11β-hydroxylase.
The Effects of Age and Urine Concentration on Lysozyme and N-acetyl-β-d-Glucosaminidase (NAG) Content in Urine
Authors: Houser Mark T
Published: February 2014

Random urine samples were obtained to evaluate potential age- or urine concentration-related differences in lysozyme or NAG content. The concentration and excretion of both enzymes was widely variable although no age-related differences were seen. Urine concentration, however, was an important variable as NAG concentration (per mL urine) and lysozyme excretion (per μmol creatinine) were significantly elevated and reduced, respectively, in samples with a higher specific gravity. The correlation coefficient between urine specific gravity and both parameters was significant. Lysozyme excretion is elevated in subjects undergoing a modest diuresis although NAG excretion is unaffected. These data may prove to be useful in the evaluation of renal dysfunction.
An Evaluation of 13 Commercial Kits for the Measurement of Testosterone in Serum and Plasma
Authors: Wheeler M J , Shaikh Munira , Jennings R D
Published: February 2014

An evaluation has been carried out of 13 commercial testosterone kits. The within- and between-assay imprecision was found to be unsatisfactory for some kits. Sensitivity and linearity were acceptable for all the kits but several showed concentration-dependent biases to the ALTM or GCMS values. The occurrence of anomalous results and changing performance characteristics of some of the direct kits is also presented.
A Modified Method for the Estimation of Galactose-1-Phosphate
Authors: Dobbie J A , Holton J B
Published: February 2014

The measurement of galactose-1-phosphate has been advocated for monitoring galactosaemia. A radioenzymatic method is described in which red-cell haemolysates are incubated with radiolabelled uridine diphospho-glucose and exogenous galactose-1-phosphate uridyl transferase. Labelled glucose-1-phosphate is formed in proportion to the amount of galactose-1-phosphate present and is separated from the labelled uridine diphospho-glucose by affinity chromatography. The method is reproducible and has a low limit of detection. This allows it to be carried out on 100 μL of packed red cells.
Sampling Errors in pH and Blood Gas Analysis—An Evaluation of Three New Arterial Blood Samplers
Authors: Hutchison A S , Dryburgh F J , Ralston S H
Published: February 2014

We have tested the accuracy, acceptability and general performance of three recently-marketed samplers for arterial blood gas measurement (the Corning Arterial Blood Sampler, the Concord ‘Pulsator’ and the Sarstedt ‘Monovette’™). All three greatly reduce or eliminate the error of venous sampling, and the Corning and Sarstedt samplers eliminate the risk of dilution of the sample by excess heparin solution. A positive bias in pO2 measurement, more marked at higher levels, was demonstrated with the Concord and Sarstedt samplers, and the latter carry a slightly increased risk of cross-infection. None of the samplers completely overcame potential sampling errors.
Comparison of an ELISA with a RIA Method for Serum Alpha-Fetoprotein Determination in Screening for Fetal Neural Tube Defects
Authors: Barlow R D , Thompson S G , Cuckle H S , Wald N J , Voller A
Published: February 2014

An enzyme-linked immunosorbent assay (ELISA) was evaluated for serum alpha-fetoprotein determination in the antenatal screening for fetal open neural tube defects. The ELISA was used concurrently with an existing radioimmunoassay (RIA) method until serum specimens from 5000 pregnant women, between 15 and 20 weeks gestation, had been tested. The accuracy of the ELISA was similar to that of the RIA; the median AFP values by gestational week obtained with the ELISA were, on average, 2 KIU/L higher than the corresponding RIA values; the 10th and 90th percentiles, in terms of multiples of the median (MoM), were very similar. The precision of the two methods was also similar. The ELISA method yielded 1·8% results from unaffected pregnancies above 2·5 MoM compared with 1·4% by RIA, a small but statistically significant difference ( P=0·03). Both methods detected the same affected pregnancies identified during this period; five open neural tube defects, three with exomphalos and three intra-uterine deaths. The ELISA method was simple, required about one quarter less operator time than the RIA and enabled results to be generated in one day rather than the two days required by RIA. The ELISA method is a suitable alternative to RIA for routine use in screening for fetal neural tube defects.
Analytical Goals for Glucose Analyses
Authors: Fraser Callum G
Published: February 2014

Analytical goals may be defined as those standards of performance required to facilitate optimal patient care. Review of the considerable amount of published work on glucose analyses allows delineation of the following current goals:

For plasma glucose: within-laboratory between-batch imprecision — CV≤2·2%; inaccuracy — no bias; linearity − 1 to 28 mmol/L; detection limit − 1 mmol/L; turnaround time − 30 min (in emergency situations). For urine glucose (quantitative): within-laboratory between-batch imprecision — SD ≤0·1 mmol/L; inaccuracy — no bias. for urine glucose (qualitative or semi-quantitative): negative — should be negative; positive — should be positive ± one positive colour block; detection limit − 2·8 mmol/L.

Moreover, each laboratory should develop goals for the many pre-analytical factors affecting glucose analyses. While the above goals are not always achieved in current practice, they are attainable and are worthy targets to strive to reach. The general principles discussed here for glucose analyses are applicable to other analytes of interest to the clinical biochemist.
Basic Principles and Problems of Haemocytometry
Authors: Lombarts A J P F , Koevoet A L , Leijnse B
Published: February 2014

After some brief remarks on counting chambers, references to the ICSH-recommended haemoglobin-determination are given. The microhaematocrit of normal blood is advocated as a potential routine calibration method. Comments are given on discrepancies between centrifugal and flow haemocytometry haematocrits of abnormal and artificial bloods. Flow haemocytometry instruments are classified into analogue and digital instruments or into electrical and optical instruments. Their hydrodynamic properties are discussed. The principles and problems of electrical and optical cell counting and sizing are dealt with. The importance of the refractive index and of flow-induced cell shape changes for the MCV determinations is stressed. It is argued that MCV and haematocrit values are exaggerated at both low and high values and consequently MCHC is erroneously constant. Various prevailing red cell distribution width (RDW) and platelet distribution width (PDW) definitions bring about considerable confusion. The major features of the counting and sizing of white blood cells and platelets are described.
The Measurement of Insulin-Like Growth Factor I: Clinical Applications and Significance
Authors: Teale J D , Marks V
Published: February 2014

Of the somatomedins so far measured, the selective quantitation of insulin-like growth factor I (IGF-I) appears to have the greatest potential in clinical diagnosis. There have been two approaches to the development of immunoassay systems. One type uses antibodies raised against synthetic fragments of IGF-I which exhibit cross-reactivity with the whole hormone. Such assay systems may be adequate for measuring normal adult plasma IGF-I levels, but the potential for the higher sensitivity required for detecting sub-normal plasma levels in young children is apparent only in methods using antibodies raised against the complete hormone.

IGF-I in plasma exists as part of a high molecular weight complex in which it is bound to carrier proteins. The binding proteins may interfere with plasma IGF-I measurements by radioligand assays. Direct analysis of untreated plasma samples is claimed to be possible using disequilibrium assay conditions but in order to maximise assay sensitivity it is necessary to employ an initial extraction stage in order to eliminate binding protein interference.

Whether the measurement of plasma IGF-I can or should be used in addition to, or as a replacement for, plasma growth hormone (GH) measurement in the clinical assessment of growth disorders remains a controversial issue. Available evidence indicates that a single, random plasma IGF-I level provides an accurate reflection of GH secretion. Adequate discrimination between the elevated levels in acromegaly and normal reference values has been demonstrated. However, in the investigation of growth-retarded children available radioimmunoassay (RIA) methods have proved only partially successful because of the age-related nature of normal plasma IGF-I concentrations. Existing assays appear capable of identifying sub-normal plasma levels after the age of approximately 4 years. In younger subjects an improvement in assay sensitivity is required in order to establish with greater accuracy the relevant normal ranges.

Improvements in the identification of the particular lesion responsible for retarded growth in a child can be achieved by measurement of both plasma GH and IGF-I concentrations. The predictive value of the acute plasma IGF-I response to single-dose GH therapy may identify patients who will respond to long-term GH therapy. Better, more informed decisions on subsequent treatment may therefore be made.

Apart from GH control, several other factors influence circulating IGF-I levels. Nutritional status can be assessed through reference to IGF-I analysis, overall catabolic or anabolic processes being associated with decreasing or increasing plasma IGF-I levels respectively.
Comparison of Three Parathyroid Hormone Assays
Authors: Nisbet Jennifer A
Published: February 2014

The efficiency of three parathyroid hormone (PTH) assays in the diagnosis of primary hyperparathyroidism has been investigated. Two assays used commercial reagents and measured the intact hormone and middle region of parathyroid hormone and the third assay employed the antiserum AS 211/32.

Although the intact and mid-molecule assays showed a greater increase in PTH above normal than the laboratory PTH assay, patients with proven primary hyperparathyroidism were not distinguished from healthy subjects in every case. The intact and in house assays gave elevated values in seven out of nine patients with proven hyperparathyroidism and the mid-molecule assay in eight out of nine assays. The intact PTH and in-house assays were more successful than the mid-molecule method in separating patients with primary hyperparathyroidism from those with hypercalcaemia due to malignancy.
Clinical and Analytical Validation of an Enzymometric Assay for Creatine Kinase-Mb isoenzyme
Authors: Youens J E B , Calvin J , Price C P
Published: February 2014

The analytical validation of an immunoenzymometric technique for the specific measurement of the creatine kinase-MB isoenzyme is described. Its application is shown in the diagnosis of myocardial infarction. A difference in the correlation of the mass and catalytic activity of the CK-MB isoenzyme is shown between patients suffering myocardial infarction and those with skeletal muscle damage.
Long-Term Trends in Biochemical Data Obtained from Two Population Surveys
Authors: Broughton P M G , Holder Roger , Ashby Deborah
Published: February 2014

A study has been made of the variations in monthly mean values of 10 serum constituents in subjects participating in two partly-concurrent long-term epidemiological surveys. Closely similar patterns of variation were found in men in both surveys and in men and women in one survey. During the 6 years of the study, four types of variation of the monthly mean concentrations were identified in varying combinations: (i) abrupt changes of less than 2% not detected by quality control procedures; (ii) a gradual drift in mean value; (iii) haphazard variations in mean values; and (iv) seasonal variations in bilirubin and urea, identical in men and women. The implications of these findings for the design of long-term epidemiological surveys, and the criteria for designating variations as seasonal, are discussed.
A Simple Method for the Measurement of Glycerol in Serum
Authors: Roberts Ian , Smith Iain M
Published: February 2014

An automated enzymic assay for the measurement of glycerol in serum is described. As it uses a centrifugal analyser, this method does not require prior extraction. It is precise, sensitive, and can be performed rapidly at low cost.
HDL-Cholesterol Subfractions in Healthy Males: Relation to Serum Triglyceride Levels and Age
Authors: Ferns G A A , Robinson D , Stocks J , Bevan E , Williams P , Galton D J
Published: February 2014

The relationship between plasma HDL-cholesterol subfractions (HDL2 and HDL3), measured using a differential precipitation method, and serum triglycerides, was studied in 402 healthy Caucasion males attending a health screening centre in London. Mean values for HDL2 and HDL3 were 0·42± 0·24 mmol/L and 0·81±0·15 mmol/L respectively. HDL2 was found to show a stronger negative correlation with serum triglyceride and a stronger positive correlation with total HDL than HDL3. HDL2 also showed a stronger correlation with age than either total HDL or HDL3. Mean levels of HDL2 were 20% higher in subjects over 55 years of age compared with those who were less than 55 years of age. Reference values of HDL2 and HDL3 are presented for different age ranges.
A Method for the Identification of Apolipoprotein E Isoforms Employing Chemical Precipitation and Flat Bed Isoelectric Focusing in Agarose
Authors: Kane J W , Gowland E
Published: February 2014

A method is described for the identification of apolipoprotein E phenotypes. Lipoproteins were precipitated by magnesium chloride/phosphotungstate reagent and isoelectric focusing performed on flat-bed agarose. Sensitivity was enhanced by blotting with nitrocellulose prior to staining. The system described requires no ultracentrifugation step and allows up to 20 samples to be processed in each run. Agarose has some advantages over the more commonly used polyacrylamide gels for isoelectric focusing.
Simple Screening Methods for Hypoxanthine-Guanine Phosphoribosyltransferase and Adenine Phosphoribosyltransferase Deficiencies Using Dried Blood Spots on Filter Paper
Authors: Nishida Y , Miyamoto T
Published: February 2014

Simple methods for the detection of hypoxanthine-guanine phosphoribosyltransferase and/or adenine phosphoribosyltransferase deficiencies using dried filter paper blood spots were studied. Enzyme activities in the eluate from dried filter paper blood spots stored for 4 weeks at room conditions were shown to be quite stable. Autoradiographs prepared from dried filter paper blood spots and DE-81 papers soaked with enzyme reaction mixtures containing 14C-hypoxanthine and/or 14C-adenine showed sharp radioactive spots in normal subjects. No activity was evident in the cases of the Lesch-Nyhan syndrome and/or adenine phosphoribosyltransferase deficiency. The methods seem to be suitable for screening.
The Interpretation of Bloodspot 17α-Hydroxyprogesterone Levels in Term and Pre-Term Neonates
Authors: Berry Janet , Betts P , Wood P J
Published: February 2014

Bloodspot 17α-hydroxyprogesterone, plasma cortisol, plasma sodium and urinary 17α-hydroxyprogesterone, cortisol, sodium and creatinine levels were determined in 24 term and 32 pre-term infants on the third, eighth and fourteenth days of life. Pre-term infants, whether ‘well’ or ‘sick’, had significantly raised bloodspot 17α-hydroxyprogesterone levels (up to 158 nmol/L) compared with those found in term infants (up to 18·8 nmol/L). Urinary 17α-hydroxyprogesterone/creatinine ratios were also higher in pre-term infants. Plasma cortisol results showed similar ranges for term and pre-term infants, and bloodspot 17α-hydroxyprogesterone/plasma cortisol ratios for day 3 specimens correlated with the degree of prematurity. These results may be due either to immature enzyme systems in the pre-term baby or to an excess of related steroids cross-reacting in the 17α-hydroxyprogesterone assay.

We propose the use of two distinct upper limits of normal of 20 nmol/L (term infants) and 200 nmol/L (pre-term infants), for the interpretation of bloodspot 17α-hydroxyprogesterone levels at the end of the first week of life.
Changes in Plasma and Buffy Layer Vitamin C Concentrations following Major Surgery: What Do They Reflect?
Authors: Schorah C J , Habibzadeh N , Hancock M , King R F G J
Published: February 2014

Plasma and buffy layer vitamin C concentrations have been measured in 19 patients before and following major surgery, and falls of 36% and 43% respectively were recorded on the first post-operative day. However, the change in the buffy layer could not be accounted for by a change in the concentration of vitamin C in platelets, mononuclear cells or polymorphonuclear leucocytes, the cell types which form the buffy layer. The buffy layer change could be explained by a post-surgical increase in the number of polymorphonuclear leucocytes which, when the buffy layer vitamin C is expressed per 108 white cells, dilutes the platelet and mononuclear cell contribution to the buffy layer vitamin C concentration. The fall in buffy layer vitamin C does not, therefore, reflect any increased demand for white cell vitamin C in the immediate post-operative period, although the decrease in plasma vitamin C could imply some increased utilisation or redistribution of the non-cellular compartment.
Evaluation of the Computing Aspects of Automatic Analysers
Authors: Clark I , Peters Margaret , Broughton P M G
Published: February 2014

Modern automatic analysers are making increasing use of microprocessor technology, which is difficult for the user, or even computer scientists, to evaluate. This paper offers some practical advice for the prospective purchaser on how to assess the capabilities and limitations of the computer hardware and software provided in such instruments, and considers some of the problems of interfacing an analyser to a laboratory computer system.
Salivary Androgens in Hirsutism: Are They of Use in Routine Evaluation?
Authors: Wang C , Wakelin K , White J , Wood P J
Published: February 2014

In the biochemical evaluation of hirsutism, 50% or less of patients have an elevated total serum testosterone. Recent work has suggested that measuring salivary testosterone or a derived serum ‘free testosterone index’ may be of use in the evaluation of hyperandrogenism. We have measured serum total, derived serum free indices and salivary concentrations of testosterone and 5α-dihydro-testosterone in an unselected group of hirsute patients in order to assess their value in the routine evaluation of hirsutism. The assays were performed using a novel oxidation procedure to overcome the need for chromatographic separation. The ‘free testosterone index’ gave the best discrimination. Salivary androgen concentrations were comparatively poor and cannot be recommended for routine use.
Single-Reagent Polarisation Fluoroimmunoassay for Cotinine (a Nicotine Metabolite) in Urine
Authors: Hansel M C , Rowell F J , Landon J , Sidki A M
Published: February 2014

A rapid, single-reagent, non-separation, non-isotopic immunoassay was developed for determining levels of the nicotine metabolite, cotinine, in urine.

The single reagent was prepared by pre-mixing an appropriate dilution of sheep anti-cotinine serum with a fluorescein-labelled cotinine tracer.

All normal reliability criteria were satisfied. The assay was found to be specific for cotinine and there was no cross reactivity with other available nicotine metabolites and structurally-related compounds. The results obtained correlated closely with those of an established radioimmunoassay. The assay was well-suited to application in the discrimination of active smokers from non-smokers (and passive smokers).