bluuebunny/crossref_metadata_2025 huggingface dataset:
Direct Determination of Total Serum Cholesterol by On-Column Gas-Liquid Chromatographic Analysis without Previous Derivatisation Compared with WHO-CDC Reference Method
Authors: Brunnekreeft J W I , Boerma G J M , Leijnse B
Published: February 2014

A method for the direct determination of total serum cholesterol by on-column gas-liquid chromatography is described. The French reference method developed by Gambert et al.1 served as a model for our method, which is fast and less laborious than the well-known CDC reference method of Cooper et al.23 based on the Abell-Kendall technique.4 The accuracy and precision of our on-column gas-liquid chromatographic method and the CDC reference method are comparable. The obvious advantage of this proposed gas-liquid chromatographic reference method is its increased analytical speed. The problem of the specificity of our method in relation to cholestanol is discussed.
Measurement of Osmolality and Sodium Concentration in Heated-Cup Sweat Collections for the Investigation of Cystic Fibrosis
Authors: Kirk Jean M , Adams A , Westwood A , McCrae W M
Published: February 2014

A new system (Wescor) for sweat collection and analysis was examined with respect to its suitability for the investigation of children suspected to have cystic fibrosis. The effects of iontophoresis current, sweat collection time, sweat storage and analysis were examined, and as a result the technique was modified to allow collection and storage of sufficient sweat for sodium and potassium as well as osmolality assays in 10–20 minutes. The small electrodes and speed of the procedure make it practical for use with small children, with a reproducibility of 13–24 % (coefficient of variation for whole procedure).
Human Prostatic Acid Phosphatase: Properties of the Native Enzyme, and the Enzyme-Antibody Complex
Authors: Bais Renze , Huxtable Anne , Edwards John B
Published: February 2014

Acid phosphatase purified from human prostatic tissue was shown to be homogeneous by polyacrylamide gel electrophoresis and N-terminal amino acid analysis. However, isoelectric focusing revealed a large number of isoenzymes which were reduced to four by digestion with neuraminidase. It is suggested that the patterns observed are due to differences in bound carbohydrate attached to the same protein backbone. Antiserum to the purified enzyme was produced in rabbits and reacted with the enzyme to form an enzymatically active complex of large molecular weight. This complex is more stable at high temperatures than the native enzyme. Kinetic analysis of both the enzyme and the enzyme-antibody complex demonstrated that the binding of the antibody caused no significant change to the active site of the enzyme.
Glycosylated Haemoglobins: Biochemical Evaluation and Clinical Utility
Authors: Miedema Kor , Casparie Ton
Published: February 2014

A review is given of the biochemical background of the glycosylated haemoglobins, their methods of determination, and their clinical significance. Special attention is paid to the sample preparation. For all methods except the colorimetric TBA-method, the removal of the labile pre-HbA1c fraction is essential. Under proper conditions, high-performance liquid chromatography, agar-gel electrophoresis and affinity chromatography are suitable methods for use in the clinical laboratory for the estimation of HbA1c and HbA1. However, the colorimetric TBA-method must be considered to be the method of choice. The clinical utility of the test is stressed with special respect to the management of diabetic pregnancies, the control of home-monitoring of blood glucose, and the objective measurement of the effect of changing diabetic therapy.
On the Reliability of the Henderson-Hasselbalch Equation in Routine Clinical Acid-Base Chemistry
Authors: Maas A H J , Rispens P , Siggaard-Andersen O , Zijlstra W G
Published: February 2014

This paper deals with the variability of the practical coefficient of the first ionisation equilibrium of carbonic acid as related to the CO2 in the liquid phase (Henderson-Hasselbalch equation)

[Formula: see text]

and that of the practical coefficient of the first ionisation equilibrium of carbonic acid as related to the CO2 in the gas phase (modified Henderson-Hasselbalch equation)

[Formula: see text]
Serum Pancreatic Enzymes in the Elderly
Authors: Mohiuddin J , Katrak A , Junglee D , Green M F , Dandona P
Published: February 2014

Immunoreactive trypsin (IRT) and pancreatic lipase were measured in serum from 37 geriatric in-patients (median age 77·5 years) without history of diarrhoea, pancreatic disease, diabetes or acute or chronic alcoholic intake. IRT and pancreatic lipase concentrations/activity were strongly correlated and were markedly elevated when compared with a control population of 22 subjects (median age 27 years). Such elevations in pancreatic enzymes indicate a subclinical damage of exocrine pancreatic tissue. Assessment of exocrine pancreatic function in the geriatric age group should not be based on pancreatic enzyme levels in serum.
Analysis of Individual Bile Acids and Their Glycine/Taurine Conjugates by High-Performance Thin-Layer Chromatography and Densitometry
Authors: Robb T A , Davidson G P
Published: February 2014

We have investigated a thin-layer chromatography method1 for the quantitative measurement of free and conjugated bile acids in duodenal juice. Evaluation of solvent systems and colour spray reagents has enabled us to select conditions which improve the resolution, sensitivity and colour stability of the method. The modified method, using high-performance thin-layer chromatography and densitometry, is rapid, accurate, reproducible and practicable. The technique deserves wider routine use.
The Effects of Inheritance on Constituents of Plasma: A Twin Study on Some Biochemical Variables
Authors: Whitfield J B , Martin N G
Published: February 2014

Heritability and within-person repeatability of thirteen constituents of plasma were assessed in a study of 206 pairs of male and female twins. Repeat measurements were available on 44 pairs. For bilirubin, calcium, creatinine, phosphate and potassium, the individuality of these characteristics was genetic in origin. Total protein, albumin and globulin showed significant heritability but considerable variation between occasions, while bicarbonate, chloride, iron, sodium and urea showed mainly environmental effects.
The Effect of Computer Generated Comments on the Distribution of Anticonvulsant Concentrations
Authors: Richardson T
Published: February 2014

Following the introduction of a consistent method of adding informative comments to the laboratory report of the plasma concentrations of the anticonvulsants phenytoin, carbamazepine and phenobarbitone, there was a significant increase in the proportion of results falling within the therapeutic range to 64, 65 and 62% respectively. This increase was mainly at the expense of results which previously fell below this range.
Measurement of Plasma Caffeine Concentrations by Substrate Labelled Fluoroimmunoassay
Authors: Pearson Sheena , Smith Janet M , Marks Vincent
Published: February 2014

Abuse or misuse of caffeine has been implicated in the pathogenesis of a variety of clinical disorders and measurement of its plasma concentration is likely to become important in clinical laboratories in the future. A rapid, sensitive and easily performed method for the measurement of caffeine in biological fluids by the technique of fluoroimmunoassay is described. The results produced are precise and agree well with those obtained by radioimmunoassay or HPLC. Cross-reactivity of the antiserum with other substituted xanthines and uric acids is negligible for the major metabolites of caffeine but there is significant cross-reactivity with theophylline at concentrations likely to be found when this drug is being administered therapeutically. The measurement of caffeine by fluoroimmunoassay has a place in the clinical laboratory particularly where small batches of samples are to be analysed.
External Quality Assessment of Immunoassays for Specific Proteins in Serum; 18 Months' Experience in the United Kingdom
Authors: Chambers R E , Whicher J T , Bullock D G
Published: February 2014

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 α1-antitrypsin (α1-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 α1-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.
Blood Pressure and Chemistry: Some Correlations and Apparent Correlations
Authors: Whitfield J B , Martin N G
Published: February 2014

The reported correlation between plasma calcium and blood pressure has been investigated in 412 young men and women. In this sample, it seemed to be due to a stronger correlation between blood pressure and plasma albumin. Blood pressures were also significantly correlated with plasma high-density lipoprotein in men and with plasma uric acid in women.
Colorimetric Assay for N-Acetyl-β-D-glucosaminidase (NAG) in Pathological Urine Using the ω-Nitrostyryl Substrate: The Development of a Kit and the Comparison of Manual Procedure with the Automated Fluorimetric Method
Authors: Yuen C T , Kind Patricia R N , Price R G , Praill P F G , Richardson A C
Published: February 2014

This paper describes a comparison of the recently developed substrate 2-methoxy-4-(2′-nitrovinyl)-phenyl-2-acetamido-2-deoxy-β-d-glucopyranoside (MNP-GlcNAc) and the corresponding 4-methylumbelliferyl substrate (4-MU-GlcNAc) for the determination of urinary NAG. A good correlation ( r = 0·977) was found between NAG activities in 366 urine samples from renal transplant patients determined by either the fluorimetric method or the colorimetric procedure. The colorimetric method may be used with confidence as an alternative to the fluorimetric assay and does have the advantage that colorimetry is widely used in clinical chemistry laboratories. Sample blanks are not normally required unless there is blood contamination in the urine which can easily be identified visually.

The incorporation of the MNP-GlcNAc substrate into a kit suitable for the assay of urinary NAG using a simple battery-operated miniphotometer is also described. The presence of elevated NAG levels in urine can be detected rapidly and this procedure is suitable for routine monitoring of renal patients in the laboratory and may prove to be suitable for use by non-laboratory personnel in clinics or on the ward.
Free Ionised Calcium—A Critical Survey
Authors: Vanstapel F J , Lissens W D
Published: February 2014

It is our aim to summarise and discuss procedures for the evaluation of the concentration of free ionised calcium in serum or plasma. Stress is laid upon the interrelations and relative validity of the most common algebraic expressions to appraise the calcium status. The multitude of formulae proposed in the literature are, by mathematical discussion, reduced to variations on a single theme. A second topic is the direct potentiometric measurement of free ionised calcium concentration. Finally we review the literature on the clinical utility of measuring or calculating the free ionised calcium concentration.
A New Alkaline Phosphatase Isoenzyme Abnormality
Authors: Mayne P D , Foo A Ying , Michelson Rosalind , Kovar I Z , Rosalki S B
Published: February 2014

We report on a new alkaline phosphatase isoenzyme abnormality occurring as an incidental finding in a male infant aged 4 months. Isoenzyme electrophoresis on cellulose acetate showed a prominent, diffuse alkaline phosphatase staining band in the α1-globulin position together with a second band in the α2/β region and minor ‘trailing’ in the intermediate α2 region. Normal liver and bone alkaline phosphatase were absent and intestinal phosphatase was not detected. On acrylamide gel electrophoresis a marked origin band was detectable suggesting the presence of high molecular weight enzyme. In addition, a series of compact bands in the α2/β position was present cathodal to the usual liver and bone isoenzymes. Total alkaline phosphatase activity was marginally elevated and was heat labile, L-phenylalanine resistant and partially L-homoarginine and L-leucine sensitive.
A Spectrophotometric Assay of Phosphoribosyl Pyrophosphate Synthetase
Authors: Braven J , Hardwell T R , Seddon R , Whittaker Mary
Published: February 2014

A simple spectrophotometric assay of phosphoribosyl pyrophosphate synthetase from human erythrocytes is described. The kinetic properties of the enzyme have been determined and are in good agreement with published results. Conditions for storing haemolysates at −20°C are described. The method is suitable for semi-automation.
Immunofixation and Immunosubtraction on Agarose Gel: An Aid in the Typing of Monoclonal Gammopathies
Authors: White W A , Attwood E C
Published: February 2014

A simple immunosubtraction technique and its application to a standard immunofixation procedure is described. Examples are presented where monoclonal immunoglobulin bands were successfully classified using immunosubtraction after other techniques had failed.
The Microheterogeneity of Human Liver and Serum Ferritins Measured on Minute Amounts of Ferritin in Crude Samples
Authors: Zuyderhoudt F M J , Linthorst C
Published: February 2014

A method is presented to measure the microheterogeneity of ferritin in μg amounts, without purifying the samples extensively. Ferritin-containing samples such as serum and homogenized liver-biopsy specimens were mixed with Sephadex G-75 and ampholines. Isoelectric focussing was performed and the pH gradient in the Sephadex was measured. The Sephadex was divided into predetermined pH ranges and the ferritin eluted from these fractions. Ferritin concentration was measured by an enzyme-linked immunosorbent assay. The method proved to be reproducible. The isoferritin profiles of different human serum and liver tissue samples were quite variable. In most cases serum ferritins focussed between approximately pH 5·5 and pH 4·9 and liver ferritins between approximately pH 5·8 and pH 5·3.

We examined whether there was a similarity in the isoferritin patterns of serum and liver of distinct patients. We also studied liver tissue and serum from a patient with haemochromatosis and from a child with iron overload of unknown origin. In the serum of our patients the isoferritin pattern had shifted to lower pI when compared with that found in liver tissue. Only in the case of a patient with transfusion iron overload were basic isoferritins measured in the serum. In this case no liver biopsy specimen was available for comparison.
An Inter-Laboratory Quality-Assurance Survey of Emergency Clinical Biochemistry Tests
Authors: Watkinson L R , Fraser C G
Published: February 2014

One hundred and thirteen Australian laboratories participated in a state-of-the-art quality-assurance survey of emergency clinical biochemistry tests. Two liquid-reconstituted lyophilised human-based serum samples, which had previously been analysed in the national general serum chemistry programme, were sent by air cargo, together with their own previously completed request forms, for analysis as emergency tests on a previously nominated date. The standard of performance of ten of the eleven most commonly performed tests was inferior to that obtained on a routine basis, as judged by the number of results outside present limits of total laboratory error from target values which had been previously set by reference laboratories. The standard of analytical performance achieved for emergency tests can and should be improved.
A Simple Method for the Measurement of Arginine in Serum
Authors: Roberts I , Smith I M
Published: February 2014

A simple method for the direct measurement of arginine in 40 μL of serum is described. The technique is rapid (22 samples within 10 minutes), inexpensive (reagent cost: £0–03 per test), accurate and relatively precise. The limit of detection is 1 mmol/L: it is therefore not suitable for normal basal arginine concentrations, but can be used when arginine concentrations are known to be raised.
A Phenytoin Assay Using Dried Blood Spot Samples Suitable for Domiciliary Therapeutic Drug Monitoring
Authors: Coombes E J , Gamlen T R , Batstone G F , Leigh P N
Published: February 2014

SUMMARY. A commercially available substrate-labelled fluorescent immunoassay procedure has been modified to create a simple rapid method for the determination of capillary phenytoin concentration in dried filter paper blood spots of patients on phenytoin therapy. The specimens are collected and despatched to the laboratory by the patient, thus domiciliary monitoring of phenytoin therapy can take place. The technique was validated by comparing the phenytoin results of simultaneously collected capillary dried blood spots and conventional plasma samples. The technique offers a convenient method for overcoming many of the practical problems of monitoring phenytoin therapy in epilepsy.
Serum Theophylline by Fluorescence Polarisation Immunoassay
Authors: Young Russell M , Smith M J , Payne R B
Published: February 2014

The Abbott TDX system utilises the principles of fluorescence polarisation and competitive binding analysis for the quantitation of drug levels in plasma. The system proved easy to use, and produced reliable results rapidly. The high cost of reagents is balanced by the fact that the reagents are stable and therefore the assays can be calibrated infrequently.
Aspirin Metabolites Causing Misinterpretation of Paracetamol Results
Authors: Badcock N R , Penna A C , Everett D S , Sansom L N
Published: February 2014

The inadequacy of single, simple arithmetic corrections for salicylate interference in the widely employed Glynn and Kendal technique for plasma paracetamol assay is highlighted by reference to an actual case of combined salicylate/paracetamol intoxication in an infant. Attention is drawn for the first time to the not insubstantial contribution to such interference made by even the minor metabolites of salicylate. The conclusion is reached that it is necessary, particularly in the assessment of paracetamol toxicity, to determine the presence of salicylate, and when present, to employ a specific method for the estimation of paracetamol.
The Association between Plasma Cholesterol, High-Density-Lipoprotein Cholesterol, Triglycerides and Uric Acid in Ethanol Consumers
Authors: Allen J K , Adena M A
Published: February 2014

The relationship between the concentrations of plasma cholesterol, high-density-lipoprotein (HDL) cholesterol, triglycerides and uric acid has been studied in relation to alcohol consumption in men attending a health-screening centre. Although it has been suggested that these metabolites are associated with each other by environmental factors, including ethanol consumption, the only correlation we have found between the variables which is statistically significantly related to alcohol consumption is that between total cholesterol and uric acid. A comparison of these correlations with epidemiological data suggests that assessment of cardiovascular risk is best done by using plasma cholesterol and uric acid levels, corrected for alcohol consumption. The correlation between HDL-cholesterol and the remaining fractions of plasma cholesterol is constant over all levels of alcohol consumption, and therefore the division of cholesterol between these fractions is apparently independent of both alcohol consumption and cholesterol synthesis.
Affinity Chromatography: A Precise Method for Glycosylated Albumin Estimation
Authors: John W G , Jones A E
Published: February 2014

A method is described for the estimation, in plasma, of glycosylated albumin, using the commercially available affinity chromatographic material Glycogel B (immobilised m-aminophenylboronic acid on an agarose support) to separate the glycosylated and non-glycosylated albumin, followed by the analysis of albumin concentration using rocket Immunoelectrophoresis.

Glycosylated albumin and glycosylated haemoglobin showed good correlation (r=0·91) when both are estimated by affinity chromatography. The glycosylated albumin method displays good within-batch (2·8–4·4% CV) and between-batch (2·9–5·4% CV) precision, and the method is not affected by haemolysis. Using this method a reference range of 2·0–5·4% was found for glycosylated albumin. Levels of glycosylated albumin in diabetics (10·06±3·23%) were found to be significantly higher ( P<0·001) than those in non-diabetics (3·72±0·85%).

It was found that loading more than 3 mg of albumin on to a 1 mL affinity column must be avoided, as this appears to overload the column.
An ‘In-House’ Method for the Assay of Serum Total Oestriol in Pregnancy Using 125I Label
Authors: Rege Vaijayanti
Published: February 2014

Commercial RIA kits for the assay of serum total oestriol using 125I label are used widely in monitoring fetal well-being in pregnancy; they are, however, very expensive for large-scale routine use. An ‘in-house’ assay using commercially available [125I]oestriol label and antiserum produced by the S.E. and S.W. Thames Regional Antibody Production Unit has been developed. Technical aspects of the method are described. The assay is compared with two commercial kits and correlates very well with one of them. The assay gives good precision and can be used with substantial savings in cost.
Performance of a Quality-Assessment Scheme for Blood Glucose Meters in General Practice
Authors: Burrin J M , Williams D R R , Price C P
Published: February 2014

We describe our experience with a quality-assessment scheme for Glucometer users in General Practice based on simultaneous blood samples taken on filter paper strips and posted to the laboratory. The accuracy of results from these blood glucose meters outside the laboratory was below generally accepted laboratory standards; 30% of results fell outside ± 20% of the laboratory value.

Only 58% of the filter paper strips sent out were returned for analysis, suggesting a lack of awareness of the benefits and importance of such a scheme by the G.P. Glucometer users.
Measurement of Urine Prostaglandin E2 as a Predictor of Acute Renal Transplant Rejection: Preliminary Findings
Authors: Thompson D , Rowe D J F , Briggs J D
Published: February 2014

A radioimmunoassay for prostaglandin E2 (PGE2) in urine was developed and validated. It was used to provide serial measurements in eight renal transplant patients. Urine PGE2 concentration was increased between 1 and 7 days before any changes in the conventional biochemical indicators of acute rejection, serum creatinine and creatinine clearance. The increases in PGE2 concentration varied from 3 to 50 times that of the previous day. These results suggest that measurement of urinary PGE2 may be useful as an early indicator of acute renal transplant rejection.
Application of Stepwise Discriminant Analysis in the Phenotyping of Plasma Cholinesterase Variants
Authors: Turner J M , Hall R A , Whittaker M , Holder R L , Kricka L J
Published: February 2014

Discriminant function analysis has been applied to the results of activity and inhibitor measurements carried out on a series of 229 specimens using benzoylcholine and butyrylthiocholine as substrate. The discriminant function was more effective in differentiating cholinesterase genotypes than either a single test or a combination of two tests.
Comparison of the Analytical Characteristics and Clinical Usefulness in Tumour Monitoring of Fifteen hCG(-β) Immunoassay Kits
Authors: Thomas C M G , Segers M F G , Whoux P C
Published: February 2014

Fifteen immunoassay kits for serum hCG(-β) measurements have been compared for their analytical characteristics and clinical usefulness in tumour monitoring. Three out of 13 radioimmunoassays and two sandwich hCG immunoassays represent the ‘one-component’ techniques for intact hCG detection since they are based on antiserum raised against intact hCG. Within this group, method-comparison slopes ranged between 0·149 and 0·374.

The remaining 10 radioimmunoassays all apply antiserum against hCG-β and are designated ‘two (or more)–component’ assays since they detect both intact hCG and the free β-subunit (‘total hCG’). For this reason these assays are of potential value for tumour monitoring. Additional criteria for this are: (1) the expression of assay results in terms of 1st IRP-hCG instead of the unstructured use of the 2nd IS or the 1st IRP-hCG-β; (2) documentation of cross-reactivities especially for the free β-subunits of hCG and hLH which are almost completely lacking; (3) establishment of the minimum detectable dose in the presence of normo-to-hypergonadotrophic hLH levels in serum (the ‘clinical sensitivity’) to allow the follow-up of tumour regression especially in the low-dose region. Method-comparison analysis for these assays revealed regression slopes between 0·001 and 0·873.
Immunoturbidimetry of Serum C-Reactive Protein in Low Concentration of Polyethylene Glycol
Authors: Byrjalsen I , Ingwersen S H
Published: February 2014

A simple, rapid immunoturbidimetric assay for determination of serum C-reactive protein is presented. In order to obtain constant sample blank values within a few minutes we found it necessary to use a low concentration (10 g/L) of polyethylene glycol 6000 in contrast to the commonly used 40 g/L PEG solution. The sensitivity of the assay presented is 7 mg/L; within-run and between-run CVs ranged respectively from 1·4% to 2·4% and from 2·1% to 5·5%. Results obtained with the proposed method correlate well with radial immunodiffusion.
The Stability of Creatine Kinase Isoenzymes Studied with Two-Site Monoclonal Antibody Assays
Authors: Jackson A P , Thompson R J
Published: February 2014

The stability of human creatine kinase isoenzymes was investigated under different storage conditions using specific two-site monoclonal antibody assays. In Tris-HCl buffer pH 7·5 or barbitone buffer pH 8·1 containing 5 g/L bovine serum albumin, the isoenzymes appeared to be stable for up to 3 weeks at 4°C but suffered a partial subunit dissociation and random reassociation after freeze–thawing; this dissociation was more pronounced as a result of freezing at −20°C rather than at −70°C. In contrast, creatine kinase isoenzymes stored in serum were stable at both 4°C and following freeze-thawing. High levels of heart type creatine kinase in serum showed only minor subunit hybridisation even after 12 h at room temperature. We conclude that in practical clinical situations, subunit hybridisation in serum samples is negligible. We recommend however, that isoenzyme standards for use in either two-site assays or radioimmunoassays should be stored frozen in normal serum from which endogenous creatine kinase isoenzymes have been previously removed.
Studies on the Nature of Prolactin-Like Immunoreactivity in Bromelin-Treated Cervical Mucus
Authors: Wang Han-Zheng , Donaldson A , Sufi SB , Jeffcoate SL
Published: February 2014

Prolactin has been reported to be present in cervical mucus at concentrations higher than those found in blood. Our initial findings appeared to confirm this and the material fulfilled criteria of validity generally applied when an immunoassay is employed on a new biological matrix, i.e. parallelism and chromatographic identity. Further experiments demonstrated that prolactin concentrations in cervical mucus were less than 40 mU/L and the prolactin-like immunoreactivity originally detected was due to the action of the enzyme bromelin which was used to liquefy the mucus. Bromelin has a similar molecular weight to prolactin and appeared to digest prolactin tracer and reduce its ability to bind antiserum in a manner paralleling the effect of adding pituitary prolactin.
The Fluorimetric Determination of the Lecithin/Sphingomyelin Ratio of Amniotic Fluid after HPLC
Authors: Gebhardt D O E , Soederhuizen W , Feyen J H M
Published: February 2014

We have investigated whether fluorimetric determination of the lecithin/sphingomyelin ratio is feasible after HPLC. We found that the saturated phospholipid, dipalmitoyl lecithin, which is secreted by the fetal lung, and which cannot be detected by ultraviolet spectrophotometry, can be determined fluorimetrically. For this purpose we have added the fluorescence-enhancing substance, 1,6-diphenyl-1,3,5-hexatriene to the effluent. With the aid of a continuous-flow system we showed that the method can be used for a rapid assay of the ratio of these phospholipids in amniotic fluid.
Evaluation of TBII Activity in Untreated Graves' Disease Using Solubilised Thyroid Membranes
Authors: Taylor J J , Young Et , Holcombe M , Kendall-Taylor P
Published: February 2014

The development and evaluation of a TSH radioligand receptor assay for TSH-binding-inhibiting immunoglobulins and its application to the study of patients with Graves' disease are described. Optimal conditions for the binding of 125I-TSH to solubilised thyroid membranes are defined. Polyethylene glycol precipitation was employed to prepare immunoglobulins from serum for assay and gave results comparable to ammonium sulphate precipitation. Immunoglobulins from normal serum did not interfere in the assay; preparations from patients with untreated Graves' disease gave positive results in 44 out of 56 cases. Coefficients of intra- and inter-assay variation were 7·0% and 9·8% respectively. The method is therefore not only sensitive and reproducible but is sufficiently simple and rapid for routine application.
Electrophoretic Studies of Serum γ-Glutamyl Transferase from Patients with Hepatoma
Authors: Hammond K D , Gravenor M J , Piesas D
Published: February 2014

Activities and isoenzyme patterns of γ-glutamyl transferase (GGT) were studied in serum samples from fifteen Bantu males suffering from primary hepatoma; the results were compared with those obtained from normal samples. Enzyme activities were significantly higher in hepatoma patients than in controls. Results with Cellogel electrophoresis and the fluorescent substrate γ-l-glutamine-7-amido-4-methylcoumarin were reproducible; two major bands of activity were observed in normal serum and three bands in hepatoma serum. The additional band seen in hepatoma serum was also detected in serum from patients with certain other disorders. With polyacrylamide gel electrophoresis using either γ-l-glutamyl-α-naphthylamide or γ-l-glutamyl- p-nitroanilide as substrates, results were inconsistent and difficult to interpret since there was a lack of specificity for GGT.
Plasma Free Testosterone—is An Index Sufficient?
Authors: Nanjee M N , Wheeler M J
Published: February 2014

Only about 50% of women who are clinically hirsute have a raised total plasma testosterone concentration; in those cases where the total testosterone is normal the free testosterone may, in fact, be raised. Since the measurement of free testosterone is tedious, workers have used an androgen index or a calculated free testosterone concentration from the measurements of total testosterone and sex-hormone-binding globulin. We have examined the correlation between measured free testosterone, a derived free testosterone and an androgen index in hirsute women, normally menstruating women and non-hirsute women on oral contraceptive therapy. These three measures of the free testosterone concentration in blood gave similar results in all cases.
The Effects of Septic Complications upon the Serum Protein Changes Associated with Thermal Injury
Authors: Moody B J , Shakespeare P G , Batstone G F
Published: February 2014

The levels of 12 serum proteins including ‘acute-phase reactants’, immunoglobulins and albumin were measured in 20 patients suffering from thermal burns. The acute-phase reactants: C-reactive protein, α-1 antitrypsin, α-1 antichymotrypsin, haptoglobin and orosomucoid, all increased in concentration. Highest levels, which showed significant correlations with injury severity, occurred at 6–8 days post-burn. The levels of albumin, α-1 lipoprotein and transferrin were decreased. The immunoglobulins IgG, IgA and IgM showed an initial decrease followed by a steady return to normal levels.

Four patients, of whom three died, developed serious sepsis. The levels of α-1 antichymotrypsin and C-reactive protein were much higher in patients with sepsis than in those without sepsis. The highest levels occurred during and often before the episode of sepsis was clinically evident. The immunoglobulins especially IgG and IgA were lower in those patients who developed sepsis than in those who did not.

The results suggest that the serum levels of either C-reactive protein or α-1 antichymotrypsin could be used both as an aid to diagnosis of sepsis and also to monitor the effect of therapy.
Cytidine Deaminase—A Marker for Pre-Eclampsia?
Authors: Baines T J , Clark A
Published: February 2014

Cytidine deaminase (cytidine aminohydrolase, EC 3.5.4.5) was measured in blood collected for routine antenatal monitoring from 590 unselected pregnant women. The enzyme measurements were made without prior knowledge of the clinical condition of the patients. Increased activity of cytidine deaminase was found in 42·9% of patients with severe pre-eclampsia, 9·1% of patients with mild pre-eclampsia and in 8·6% of normal pregnancies. These results show a poor correlation of elevated cytidine deaminase activity with pre-eclampsia and a significant false positive elevation of the enzyme activity in normal pregnancies.
The Influence of Age and Sex on Tests of Thyroid Function
Authors: Franklyn J A , Ramsden D B , Sheppard M C
Published: February 2014

Serum concentrations of total thyroid hormones, thyroid hormone binding proteins, free thyroid hormones and thyroid stimulating hormone (TSH) were measured in a large group of healthy normal subjects ( n = 218) to determine the influence of age and sex on tests of thyroid function.

No effect of age on measurements of total thyroxine (T4), total triiodothyronine (T3) or reverse T3 was evident. Concentrations of free T4, free T3 and TSH were similarly unaffected, suggesting that increasing age alone does not significantly influence thyroid hormone measurements. There was, however, a rise in thyroxine-binding globulin (TBG) concentration with increasing age and a fall in thyroxine-binding prealbumin (TBPA).

An influence of sex on tests of thyroid function was clearly evident. Levels of total T4, total T3, free T4 and the T4: TBG ratio were lower in women between 16 and 49 years than in men, despite an increase in TBG. Lower levels of free T3 were confined to the group of women aged 16–29 years. TSH values were unaffected by sex. These results suggest that sex hormone status in the pre-menopausal female subject may result in an increase in TBG concentration, and in addition may have an opposing effect on circulating thyroid hormone concentrations.
Clinical Value of a Sensitive Immunoradiometric Assay for TSH
Authors: Allen K R , Scott R D M , Hewitt J V , Watson D
Published: February 2014

We have investigated a sensitive immunoradiometric assay for serum thyroid-stimulating hormone (TSH) in 45 thyrotoxic patients not on treatment, 464 euthyroid patients and 111 hypothyroid patients on replacement therapy. Forty-three thyrotoxic and seven euthyroid patients were found to have an undetectable TSH (less than 0·2 mlU/L). Previous work has shown a very clear separation of thyrotoxic and euthyroid patients using sensitive TSH assays. However, our extended study here has revealed that a significant number of euthyroid patients with undetectable TSH (1·5% in our study) are likely to be found if TSH becomes the initial test for thyroid function.

Thirty of the hypothyroid patients on thyroxine were found to have undetectable TSH, but only one showed clinical signs of thyrotoxicosis. Most of the patients, although having raised serum free T4, had serum free T3 levels within the euthyroid range or just slightly elevated.
Non-Electrode Biosensors in Clinical Biochemistry
Authors: Owen Valerie M
Published: February 2014

This review covers biosensors based on piezoelectric crystals, optical systems, field effect transistors and thermistors. Piezoelectric crystal or microgravimetric biosensors have been used for immunoassay. Optical biosensors are described in which waveguides are used to transmit changes in optical characteristics or, in an innovative mode, the evanescent wave component of a completely internally-reflected light beam is used to study optical changes. Optical biosensors have been used in immuno and in enzyme-based assays. Field effect transistors detect changes in ion concentrations and have been applied to the detection of biochemical reactions which involve a change in concentration of a specific ion. Thermistors are used to monitor the heat produced as the result of an exothermic enzymatic reaction and this has been applied to the assay of compounds or enzymes of interest. Biosensors may find a role in clinical biochemistry in low volume testing, patient self-testing and in vivo monitoring.
The Measurement of Albumin in Serum and Plasma
Authors: Hill P G
Published: February 2014

This publication was prepared at the invitation of the Analytical Methods Working Party of the Scientific Committee of the Association of Clinical Biochemists, but does not necessarily reflect the views of the Scientific Committee.
Practical Assessment of the NBT-PABA Pancreatic Function Test Using High Performance Liquid Chromatography Determination of P-Aminobenzoic Acid in Urine
Authors: Berg J D , Chesner I , Lawson N
Published: February 2014

A practical method for determining p-aminobenzoic acid in urine by high-performance liquid chromatography has been assessed. The technique is quick, requires no extraction steps and has good precision. Using this method, healthy individuals had a p-aminobenzoic acid excretion index of 94% ±18 (mean±1 SD). Patients with proven, severe chronic exocrine pancreatic dysfunction had index values of <5–25%. Unlike chemical methods available, there were no interferences in any of the urines tested, nor did 12 compounds tested interfere with the analysis.
Intra-Individual Variation: Significant Changes in Parameters of Lipid and Carbohydrate Metabolism in the Individual and Intra-Individual Variation in Different Test Populations
Authors: Godsland IF
Published: February 2014

Fasting serum triglyceride, cholesterol, HDL cholesterol, HDL2&3 cholesterol, fasting plasma glucose and insulin and haemoglobin A1 were measured under standardised conditions in a group of laboratory volunteers. Intra-individual variation was calculated for each parameter from weekly measurements on at least eleven successive occassions, and the minimum change in each parameter that would be significant at the level P < 0·05 was calculated.

A further study compared intra-individual variation in different test populations. Data from the group of laboratory volunteers were taken to represent intra-individual variation under standard test conditions with an informed test population and data from a group of regularly monitored out-patients undergoing drug therapy for hypercholesterolaemia were taken to represent intra-individual variation under standard conditions in a typical test population. A group of inpatients under strict dietary control provided information on variation under extreme standardisation of test conditions. Intra-individual variation was greatest for all parameters in the outpatient population. Extreme standardisation of test condition reduced intra-individual variation beyond that of the laboratory volunteers only in the case of serum triglyceride.
Methods of Assigning Accurate Values to Reference Serum. Part 2. The Use of Definitive Methods, Reference Laboratories, Transferred Values and Consensus Values
Authors: Eldjarn L , Broughton P M G
Published: February 2014

Eight analytes (Ca, Cl, cholesterol, glucose, Mg, K, Na and urate) have been determined in one horse serum masterlot by up to six different procedures: (i) by so-called definitive methods; (ii) by a group of reference laboratories using a variety of analytical methods; (iii) using the results of two independent external quality assessment schemes; (iv) by transferring values from a human serum standard reference material analysed by definitive methods; (v) by similar transfer of values from several batches of horse reference serum previously analysed by definitive methods; and (vi) as in (v) but using a group of reference laboratories. The results have confirmed the validity and usefulness of the transfer process in value assignment and in identifying outliers due to inaccurate methods. Definitive methods are shown to be subject to error, and although they appear to be the most accurate single techniques currently available, they are not definitive in the sense of being without bias and having no known source of inaccuracy.
Single-Reagent Polarisation Fluoroimmunoassay for the Cocaine Metabolite, Benzoylecgonine, in Urine
Authors: Colbert D L , Smith D S , Landon J , Sidki A M
Published: February 2014

A polarisation fluoroimmunoassay is described for the detection in urine of benzoylecgonine, the major metabolite of cocaine. The method uses a single reagent comprising sheep anti-benzoylecgonine serum pre-mixed with a fluorescein-labelled benzoylecgonine derivative as tracer. Under the assay conditions the antiserum has equal cross-reactivity with cocaine and the metabolite. The test is performed by the addition of 10 μL of urine to an aliquot of the single reagent, incubation for a few minutes and measurement of fluorescence polarisation. The assay has a positive/negative cut-off level of 1 mg/L benzoylecgonine and results compare favourably with the EMIT-d.a.u.™ (Syva) system.
Radioimmunoassay of Buprenorphine with Iodine Label: Analysis of Buprenorphine and Metabolites in Human Plasma
Authors: Hand C W , Baldwin D , Moore R A , Allen M C , McQuay H J
Published: February 2014

Quantitative analysis of potent opiate drugs in plasma by radioimmunoassay is potentially inaccurate because of the occurence of cross-reacting metabolites. This paper describes the chemical synthesis of buprenorphine-3- O-glucuronide, a metabolite of buprenorphine, and an extraction procedure coupled with radioimmunoassay which allows the sensitive and specific measurement of buprenorphine using an iodinated buprenorphine derivative. The measurement of extracted and unextracted samples using two different antisera allowed investigation of the metabolism of buprenorphine. In four patients who had taken sublingual buprenorphine for at least one month, N-dealkyl buprenorphine was present in similar concentrations to those of buprenorphine, while buprenorphine-3- O-glucuronide was present in two to three times those concentrations.
Evaluation of an Aldosterone Radioimmunoassay: The Renin—Angiotensin—Aldosterone Axis as a Function of Sex and Age
Authors: Sequeira S J , Loughlin T , Cunningham S , Culliton M T , Hannon S , Heffernan A , McKenna T J
Published: February 2014

A highly specific radioimmunoassay for aldosterone in plasma has been developed utilising extraction from plasma into dichloromethane, an antiserum raised to aldosterone-3-carboxy-methyloxime-BSA and a radio-iodinated derivative of aldosterone. The plasma values obtained after only extraction correlated very well with the results following chromatography over celite. The within- and between-batch variations for plasma pools ranged between 5 and 15%. The range obtained, 100–1806 pmol/L for 96 random upright subjects, was comparable to others reported. Measurement of plasma aldosterone and plasma renin activity in these subjects showed that both these parameters are higher in subjects under 40 years of age than in those over 40. In addition, plasma aldosterone levels are higher in women than in men even though their plasma renin activity levels are similar. The plasma aldosterone/renin activity ratios which provide an index of adrenal sensitivity to stimulation, are lower in men than in women. The findings in this study suggest that higher aldosterone levels in younger subjects are associated with greater stimulation of the adrenals than in older subjects and that the adrenal is more sensitive in women than in men.
Testosterone Assays: Guidelines for the Provision of a Clinical Biochemistry Service
Authors: Ismail A A A , Astley P , Cawood M , Short F , Wakelin K , Wheeler M
Published: February 2014

Approximately one year after the devolution of testosterone assays from the SAS, the Analytical Methods Working Party of the Association of Clinical Biochemists set up a working party to investigate the performance of the assays, to survey the available methodology and to give guidance on the factors that influence the assay. This document represents a summary of the deliberations of the group and forms one of a series of similar reports.
A Fluorimetric Method for Measurement of Erythrocyte Transketolase Activity
Authors: Anderson Stuart H , Nicol Andrew D
Published: February 2014

A method for measuring erythrocyte transketolase activity (ETKA) is described that is precise, economical of reagents and capable of high throughput with partial or full automation. The transketolase-dependent transformation of ribose-5-phosphate, yielding glyceraldehyde-3-phosphate, is linked via ‘indicator enzymes’ to glycerol production and NADH consumption, the latter being followed fluorimetrically. Conditions under which ETKA and ‘TPP Effect’ are derived have been examined and optimised. Values are comparable with those obtained by other methods but a relatively narrow adult reference range for ETKA is observed. Data are presented for optimal preparation and storage of samples.
The Measurement of Plasma Acetate by a Manual or Automated Technique in Diabetic and Non-Diabetic Subjects
Authors: Smith R F , Humphreys S , Hockaday T D R
Published: February 2014

A method is described for the measurement of acetate in plasma by an enzymatic technique using acetate kinase, either manually or with the Multistat centrifugal analyser. The technique was used to compare concentrations in diabetic and non-diabetic subjects and to determine correlates with other intermediary metabolites.
Evaluation of an Immunoradiometric Assay for the Detection of an Ovarian Tumour Marker, CA125, in Serum
Authors: Shelley M D , Fish R G
Published: February 2014

An immunoradiometric assay, that uses a monoclonal antibody attached to a solid support and developed for the detection of the ovarian tumour antigen, CA125, in serum, has been evaluated. The method was simple to perform, with reagents having a shelf-life of approximately 4 weeks. The potentials and limitations of this test are discussed.
A Direct Assay for Pyridoxal 5′-Phosphate Using Pig Heart Apo-Aspartate Transaminase
Authors: Singkamani Ratree , Worthington D J , Thurnham D I , Whitehead T P
Published: February 2014

The development of a simple enzymatic method for the determination of blood and plasma pyridoxal 5′-phosphate (PLP) using pig heart apo-aspartate transaminase (apo-AST) is described. The technique requires three steps: (1) sample extraction using perchloric acid, (2) a binding step in which PLP in the sample extract is attached to the apo-AST and (3) the enzymatic assay of the reconstituted holo-AST. PLP extracts were analysed with and without a known concentration of added PLP to correct for variation in recovery between different specimens. Procedures are outlined for manual and automatic analysis of the PLP extracts. Using the KONE Clinical Analyser after the extraction step, it is possible to measure enzyme activity in 100 specimens (i.e. 400 tubes) in a 5 h period. Results are shown from 185 healthy women aged 20–45 years, in which plasma PLP concentrations ranged from 5 to 165 nmol/L, and 142 men and 56 women in Government service aged 17–64 years, whose plasma PLP ranged from 8 to 169 nmol/L. Values less than 20 nmol/L are believed to indicate vitamin B6 deficiency and the method is able to measure 5 nmol/L.