bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Chlorpromazine in Serum by Radioreceptor Assay and HPLC
Authors: Krska J , Addison G M , Soni S D
Published: February 2014

A radioreceptor assay for chlorpromazine in serum, which is based on binding to dopamine receptors, is described. This method has been postulated to measure all active metabolites as well as the parent drug. We have compared this method with an HPLC method for chlorpromazine. Dopamine-blocking activity, measured in serum samples from schizophrenic patients receiving chlorpromazine, was 1·85–9·1 times higher than serum chlorpromazine level measured by HPLC. The correlation between the two methods was 0·75. Dopamine-blocking activity was related more closely to dose of drug and to serum prolactin level than was serum chlorpromazine level measured by HPLC.
The Effect of Hydropenia and Oral Water Loading on Renal Lysozyme Handling and N-Acetyl-β-d-Glucosaminidase Excretion in Man
Authors: Houser Mark T
Published: February 2014

To substantiate the effects of urine flow rate on renal lysozyme handling and N-acetyl-β-d-glucosaminidase (NAG) excretion, experiments were performed in normal human subjects. Urine flow rate was varied by overnight fluid deprivation and progressive diuresis induced by oral water loading. Lysozyme measurements were made using an improved turbidimetric method and NAG determinations using a modified fluorometric assay utilising individual recovery techniques. Fractional lysozyme clearance and lysozyme excretion demonstrated a nearly linear relationship with urine flow rate ( r=0·78, r=0·80, P<0·0005), and both were elevated significantly in samples obtained during diuresis. NAG excretion, however, demonstrated a significant but weak correlation ( r=0·47, P<0·005) with fractional urine flow rate. A significant ( P<0·05) difference in NAG activity occurred only during the period of hydropenia, when a decrease in excretion was observed. These findings suggest that the effect of diuresis on lysozyme excretion should be considered in studies utilising this enyzyme as a marker of renal injury.
The Blunder-Rate in a Clinical Biochemistry Service
Authors: Chambers Anne M , Elder Jennifer , O'Reilly D ST J
Published: February 2014

We describe a study undertaken to investigate the frequency and type of mistake detected in a large biochemistry laboratory. Blunders were recorded over three non-consecutive 3-week periods. The returns to the external quality assessment schemes during a 12-month period were also monitored. Despite changes in laboratory practice, the nature of the errors found has not altered substantially from those described by earlier investigators. The detected blunder rate was 0.3%.
Δ-Aminolaevulinic Acid Dehydratase as an Index of the Presence and Severity of Lead Poisoning in Acute and Chronic Lead Exposure
Authors: Lolin Yvette , O'Gorman Patrick
Published: February 2014

The activity of δ-aminolaevulinic acid dehydratase (ALA-D; porphobilinogen synthase) was measured in whole blood from a group of workers with acute exposure to lead and with low blood lead levels, a group of workers with chronic lead exposure and high blood lead levels, and a group of people without undue environmental lead exposure. The activity of ALA-D was reduced significantly at low blood lead levels only if undue exposure to lead had occurred, and was thus a reflection of low level lead poisoning. In chronic lead exposure the enzyme was not invariably reactivated fully with dithiothreitol, indicating more severe enzyme poisoning. The one lead worker with symptomatic lead poisoning had the most marked enzyme suppression. Measurement of both ALA-D activity and blood lead levels was more useful than the measurement of blood lead levels alone in the diagnosis and assessment of the severity of lead poisoning.
The Adjusted Serum Calcium Concept—A Reappraisal
Authors: Ashby J P , Wright D J , Rinsler M G
Published: February 2014

The relationship between serum calcium and albumin was studied using a data base containing biochemical results on approximately 687 000 samples. To exclude patients with established bone, liver and kidney disease, calcium and albumin values had to be accompanied by additional results falling within the laboratory reference range for urea, phosphate, globulin, alkaline phosphatase and aspartate transaminase activities. The regression coefficients of calcium on albumin changed significantly following a change of instrumentation, even though the analytical principles of the methods remained the same. In addition, using standard laboratory methods, the relationship between calcium and albumin deviated from linearity at albumin concentrations less than 30 g/L. Care is needed in the selection and clinical application of factors for the adjustment of serum calcium for changes in the concentration of circulating albumin. Using a large data base, an albumin-related reference range for serum calcium may be calculated, eliminating the need for adjusting calcium values.
Measurement of Erythrocyte Acetylcholinesterase and Plasma Cholinesterase Activity by a Differential pH Technique
Authors: Barenghi L , Ceriotti F , Luzzana M , Ripamonti M , Mosca A , Bonini P A
Published: February 2014

We describe a new electrochemical method for the determination of erythrocyte acetylcholinesterase activity (EC 3.1.1.7) and plasma cholinesterase (EC 3.1.1.8) activity, based on the measurements of pH variation due to release of acetic acid from acetylcholine. The major advantages of the differential pH procedure are simplicity, high reproducibility, no need for pre-treatment of samples, automatic correction of sample blanks, and speed and direct measurement of enzymatic reaction. The proposed methods are linear up to 7400 U/L at 30°C and correlate well with the manual spectrophotometric method of Ellman1 for plasma cholinesterase and for washed erythrocytes. We adapted the same technique for the determination of erythrocyte cholinesterase using whole blood as sample and quinidine sulphate as inhibitor of pseudocholinesterase.
Bence Jones Protein Detection: A Rapid Immunoblotting Technique for Routine Use on Unconcentrated Urine
Authors: Heys Anthony D , Norden Anthony G W , Fulcher Leah M , Flynn Frederick V
Published: February 2014

A new immunoblotting method is described for the detection of Bence Jones proteinuria by the routine laboratory. Unconcentrated urine specimens are subjected to electrophoresis on agarose gels. Separated proteins are transferred to a nitrocellulose membrane and the immunoglobulins located and identified by horseradish-peroxidase double-antibody staining. The new method has been compared with that used routinely, and an improved rate of detection of both Bence Jones protein and intact urinary monoclonal immunoglobulin has been obtained. Among urine specimens received for routine testing for Bence Jones protein from 83 patients, 64 monoclonal components were found by the new technique compared with 45 by the method used routinely. Other advantages of the new procedure include: no need to concentrate urine specimens before electrophoresis; unlike immunofixation, the proteins may be detected successfully over a wide concentration range without using several specimen or antibody dilutions; and interpretation is easier.
External Quality Assessment of Serum Enzyme Activity Assays and the Effect of Calibration on Interlaboratory Concordance
Authors: Bullock David G , Moss Donald W , Whitehead Thomas P
Published: February 2014

The design and results of a UK external quality assessment scheme for six enzymes are described, from 21 surveys over a period of 7 years. Improvements in interlaboratory agreement and the adoption of reliable methods are documented. The potential of enzyme calibration materials in further improving numerical concordance between laboratories using different assay conditions, including temperature, is demonstrated and discussed.
Micro-Scale Ultracentrifugation as an Alternative to Ultrafiltration for the Determination of the Unbound Fraction of Phenytoin in Human Serum
Authors: Jack L , Cunningham C , Watson I D , Stewart M J
Published: February 2014

Free phenytoin has been determined using micro-scale ultracentrifugation followed by analysis by EMIT. The effect of temperature on the determined free fraction was investigated and the ultracentrifugation procedure validated against ultrafiltration. Ultracentrifugation gave free fractions which were on average 16% lower than those obtained using ultrafiltration, but correlation was good, as was the correlation with measurements of total phenytoin ( r=0·90). Micro-scale ultracentrifugation is a simple procedure which can be of great utility in the measurement and investigation of free drug levels.
Glycosylated Serum Proteins and Glycosylated Haemoglobin in Normal Pregnancy
Authors: Van Dieijen-Visser M P , Salemans T , Van Wersch J W J , Schellekens L A , Brombacher P J
Published: February 2014

Glycosylated haemoglobin (HbA1) and glycosylated serum protein concentrations (fructosamine) were monitored in 162 normal pregnancies. The response to the standard 75 g oral glucose tolerance test (OGTT) was used to exclude gestational diabetes. A significant increase in glucose intolerance, measured from the area under the OGTT-curve ( r=0.29, P<0.0005) and a highly significant decrease in serum albumin concentration ( r=−0.79, P<0.0005) due to the redistribution of body water, as occurs during pregnancy, resulted in a statistically significant decrease in serum fructosamine concentration ( r=- 0.23, P<0.01) when related to gestational age in weeks.
Proteinuria following Trauma
Authors: Gosling Peter , Sutcliffe Anne J
Published: February 2014

Thirteen trauma patients admitted to a major injuries unit were classified according to their injury severity. Urinary excretion of total protein, albumin and gamma glutamyl transpeptidase (GGT) activity were assessed over the following 6 days. All patients showed an initial glomerular and tubular proteinuria during the first 24 h which subsided by the second post-trauma day. The excretion of total protein and albumin was positively correlated with injury severity. Those patients with the severest injuries showed a marked recurrent total proteinuria around days 3 to 4 post-trauma which exhibited features of a tubular lesion. The recurrent proteinuria peak coincided with peak levels of serum c-reactive protein (CRP).
Biochemical Abnormalities in Anorexia Nervosa and Bulimia
Authors: Mira Michael , Stewart Peter M , Vizzard Jeanette , Abraham Suzanne
Published: February 2014

We report the biochemical results in 90 women presenting to an eating disorders clinic: 61 who had bulimia, 22 with anorexia nervosa and seven unclassified. The results were compared with 30 control women. The group of women with an eating disorder had significantly higher concentrations of total CO2, calcium, AST, ALT, ALP, albumin and cholesterol and significantly lower concentrations of potassium, chloride and phosphate in the plasma. The elevated calcium could be accounted for in part by an increase in total CO2 and an increase in albumin. Hypokalemia was strongly associated with self-induced vomiting and laxative abuse. Biochemical abnormalities occurred in both forms of eating disorders; however, hypercholesterolaemia was more common in anorexia nervosa and abnormal liver enzymes were more common in bulimia.
Radioimmunoassay of Blood-Spot 17α-Hydroxyprogesterone in the Management of Congenital Adrenal Hyperplasia
Authors: Robinson Janet A , Dyas J , Hughes I A , Riad-Fahmy Diana
Published: February 2014

A robust assay for routine measurement of blood-spot 17α-hydroxyprogesterone (17-OHP) concentrations has been developed using a magnetisable, solid-phase antiserum and an 125I-radioligand. The working range of this assay (13.5–500 nmol/L) is well suited for the initial diagnosis of congenital adrenal hyperplasia (CAH) and for monitoring replacement therapy in CAH patients. Data derived from multiple blood-spot samples, collected on two consecutive days, provide 17-OHP profiles. These profiles have been used to construct a chart allowing a rapid visual assessment of the efficacy of replacement therapy in CAH patients. Measurement of 17-OHP in the blood-spots of over-treated patients and accurate determination of normal range values in healthy infants relied on development of a sensitive assay (range 1.7–34 nmol/L). In the blood-spots of normal male ( n=50) and female ( n=50) infants collected 5–7 days after birth, 17-OHP concentrations were 7.62±2.55 nmol/L and 7.32±2.87 nmol/L respectively. Retrospective measurement of this steroid in samples from known CAH patients ( n=4), which had values ranging from 224 to 2145 nmol/L, support a role for measurement of blood-spot 17-OHP in high-risk screening programmes.
Analysis of Morphine and its Major Metabolites by Differential Radioimmunoassay
Authors: Hand C W , Moore R A , McQuay H J , Allen M C , Sear J W
Published: February 2014

The analysis of morphine, morphine-3-glucuronide (M-3-G) morphine-6-glucuronide (M-6-G) by differential radioimmunoassay using idodinated label and three different antisera is described. These methods were used to measure concentrations of morphine and its conjugated metabolites in human plasma, over a 3-h period, following a single 10 mg intravenous dose. In 13 patients peak concentrations of M-3-G (739 nmol/L±73.7 SEM) were approximately 10 times greater than those of M-6-G (71-3 nmol/L±8-6 SEM). Times to reach these peaks were similar for both metabolites. Decay of morphine from plasma followed a biexponential pattern with a mean terminal half-life of 59.3 min (±81 SEM, n=11). Accurate determination of the half-lives of the glucuronides was not possible due to the short sampling period, but M-6-G seemed to have a similar half-life to morphine, while M-3-G was eliminated more slowly.
Determination of 4-Hydroxy-3-Methoxymandelic Acid in Urine using HPLC with Electrochemical Detection
Authors: Palfrey S M
Published: February 2014

A method is described for the assay of 4-hydroxy-3-mcthoxymandelic acid (HMMA) in urine using IIPLC coupled with electrochemical detection. In this method acidified urine is extracted with ethyl acetate which is then washed with the chromatography solvent to back extract HMMA. The solvent is a pH 50 citrate buffer. At this pH, HMMA separates clearly from all other electroactive compounds present in urine.
Quantitative Measurement of Blood Pigments in Cerebrospinal Fluid by Derivative Spectrophotometry
Authors: Stroes J W , Van Rijn H J M
Published: February 2014

A spectrophotometric method for the simultaneous calculation of the concentrations of oxyhaemoglobin, methaemoglobin and bilirubin in cerebrospinal fluid is described, based on the first and second derivative spectrum between 350 and 650 nm. Specificity compares favourably with other methods currently in use. The proposed method minimises the effect of turbidity and permits the measurement of concentrations below 0–3 μmol/L.
Oestrogen and Progesterone Receptor Concentrations in Leiomyoma and Normal Myometrium
Authors: Sadan O , Van Iddekinge B , Van Gelderen C J , Savage N , Becker P J , Van Der Walt L A , Robinson M
Published: February 2014

The content of cytoplasmic 17β oestradiol and progesterone receptors in human uterine leiomyoma and normal myometrium in the Negroid population was determined. Eighteen women of reproductive age, at various stages of the menstrual cycle, were included in the study. The serum oestrogen and progesterone concentrations were also measured. This is the first report in the literature in which oestrogen and progesterone receptors in leiomyoma are significantly higher than in normal myometrium ( P=0·0002). The steroid dependence of the growth of leiomyomas may be related to the steroid receptor level. The presence of persistently high concentrations of oestrogen and progesterone receptors in leiomyoma should be helpful in the treatment of this benign tumour.
The Production and Use of Monoclonal Antibodies to Measure Apolipoprotein B by a Competitive Enzyme-Linked Immunoassay
Authors: Waterson M , Samuel L , Norman M
Published: February 2014

The production of monoclonal antibodies to human lipoproteins is described. One of these antibodies, which was shown to be specific to apolipoprotein B, was used to develop a competitive enzyme-linked immunoassay for apolipoprotein B in serum samples. The antibody selected recognises apolipoprotein B in both low density and very low density lipoprotein particles, but there is no cross-reactivity with high density lipoprotein. There is no requirement for labelling of antigen or antibody used in the assay, and results obtained correlate well ( r=0·88) with measurements on serum samples using a radial immunodiffusion assay for apolipoprotein B.
Total Parenteral Nutrition and the Clinical Chemistry Laboratory
Authors: Marshall William J , Mitchell Peter E G
Published: February 2014

Parenteral nutrition is a well-established technique for feeding patients with intestinal failure and other conditions which render enteral feeding impossible. Biochemical tests are required in the initial assessment of these patients, for monitoring their response to treatment and for the detection and management of complications. The use of these tests is discussed critically and guidelines are provided for the frequency with which they should be performed. Chemical pathologists and clinical biochemists have an important role in the provision of parenteral nutrition as members of multi-disciplinary nutrition teams.
Factors That Affect the Induction of Gamma Glutamyltransferase in Epileptic Patients Receiving Anti-Convulsant Drugs
Authors: Braide Solomon A , Davies T J
Published: February 2014

Serum samples from 335 epileptic patients receiving one or more anticonvulsant drugs, phenobarbitone, primidone and phenytoin, have been analysed for biochemical liver profile (BLP) and serum drug concentration.

The results show that the induction of serum gamma glutamyltransferase (GGT) is affected by the sex and age of the patient, type of anti-convulsant drug prescribed and duration of treatment. It is less affected by serum drug concentration.

It is suggested that these factors must be considered when interpreting results involving serum GGT activity as the index of microsomal enzyme induction.
Serum Digoxin Assays: Investigation of Use and Abuse
Authors: O'donnell J G , Paterson N C , Pledger D R , Stewart M J
Published: February 2014

Digoxin requesting patterns were studied prospectively over a 6-month period. Clinicians were not forewarned that the study was being undertaken. Many samples received in the laboratory were taken at incorrect times after the drug had been given. This led to inappropriate action being taken in some cases. Appropriate action was taken on most patients who had toxic serum digoxin levels together with clinical signs. The role of subtherapeutic digoxin levels seems unclear as these elicit a wide variety of responses.
Evaluation and Clinical Application of a Two-Site Immunoradiometric Assay for Alpha-1-Foetoprotein Using Readily Available Reagents
Authors: Stevenson J D , Chapman R S , Perry B , Logue F C
Published: February 2014

The development and evaluation in routine clinical practice of a simple, rapid, high-throughput, immunoradiometric assay (IRMA) for alpha-foetoprotein (AFP) in serum and amniotic fluid is described. The assay uses readily available reagents; a radioiodinated mouse monoclonal antibody produced by the authors and the immunoglobulin G (IgG) fraction of a polyclonal sheep anti-human-AFP serum covalently linked to Sepharose CL-4B. Both antibodies are distributed by the Scottish Antibody Production Unit (Law Hospital, Carluke).

The results of an extensive comparative trial between the IRMA and a radioimmunoassay (RIA) are presented. A high-dose ‘hook’ effect is not a problem in this system. Quantitative recovery was obtained, independent of the assay diluent. The IRMA has high sensitivity and a wide working range. Improved assay precision allowed a clinically significant change in the intervention limits.
The Effect of Long-Term Metabolic Control on Free Thyroid Hormone Levels in Diabetics during Insulin Treatment
Authors: Parr J H
Published: February 2014

Serum concentration of free T3 and, in female patients, FT4, were found to be lower in 20 asymptomatic, moderately-poor or well controlled, diabetics treated with insulin than in a group of non-diabetic subjects. Over a mean 3-month period of the study a significant fall occurred in HbA1 concentration in both groups of diabetics without change in free thyroid hormone levels. The mean capillary blood glucose, fasting free insulin and fasting lipid concentrations, other than high density lipoprotein (HDL) cholesterol, did not change. No correlations were found between the changes in HbA1 and free thyroid hormone concentrations. Improvement in long term metabolic control did not influence free thyroid hormone levels in well controlled and moderately-poor controlled diabetics, taking insulin.
Determination of Iron in Cardiac and Liver Tissues by Plasma Emission Spectroscopy
Authors: Collins W , Taylor W H
Published: February 2014

A simple plasma emission spectroscopic method for the determination of iron in liver and cardiac tissue is described. Using this technique, iron was extracted quantitatively from liver tissue of mass 14·2 to 65·4 mg wet weight, and heart tissue of mass 5·9 to 27·4 mg wet weight. Iron added to liver as aqueous ferric nitrate was recovered in the range 93 to 108%. Reference ranges for liver and myocardial iron on post mortem tissue gave respectively mean values of 0·841 mg/g dry weight (Range 0·310 to 1·600, n = 37) and 0·340 mg/g dry weight (Range 0·290 to 0·470, n = 8). Data on patients with haemochromatosis and transfusion siderosis are also presented.
Atrial Natriuretic Peptide—The Influence of Various Physiological and Sampling Conditions
Authors: Tan A C I T L , Rosmalen F M A , Theelen B G A , Kloppenborg P W C , Benraad H B , Benraad Th J
Published: February 2014

A study of various physiological conditions, possibly influencing levels of atrial natriuretic peptide (ANP), is described. Atrial natriuretic peptide was determined by a radioimmunoassay, suitable for routine measurements, using 1 mL of human plasma. Atrial naturetic peptide was adsorbed onto Sep-pak C-18 cartridges, eluted with acidified ethanol and subsequently radioimmunoassayed. The detection limit was slightly less than 2 pg/tube (∼5 pg/mL plasma). Intra- and interassay coefficients of variation were 7 and 10%, respectively. Study of various sampling conditions revealed that blood sampling in EDTA-tubes kept on ice, and centrifuged within 1 h, gives the most reliable results. Reference values in 74 individuals ranged between 10 to 69 pg/mL (mean ± SD = 30± 11 pg/mL). We observed no difference in reference values when the blood sampling procedure was in the sitting (29 ± 11 pg/mL, n = 43) or supine (31 ± 12 pg/mL, n = 31) position. Venepuncture stress did not consistently change ANP-levels. No difference was observed in ANP between the follicular and the luteal phase of the menstrual cycle. ANP levels of 7 ambulant female subjects declined significantly during the study period from 7 a.m. to 3 p.m.
Radial Diffusion as a Simple and Rapid Method for Screening Superoxide Dismutase Activity
Authors: Hunaiti A
Published: February 2014

Superoxide dismutases are of great interest due to their increasing medical applications in therapy and diagnosis of some diseases. The radial diffusion assay was evaluated for its usefulness as a simple, cheap and accurate assay for screening superoxide dismutase activity. In this assay O2− radicals were generated from the interaction of reduced riboflavin with molecular oxygen upon exposure of agar gel containing riboflavin and N,N,N̄,N̄-tetramethylethylene diamine (TEMED) to light. If nitrotctrazolium dye is also present, it will be reduced to the blue insoluble formazan, whilst if superoxide dismutase is present it will prevent this blueing.1 The developed assay was found to give reproducible estimates of pure samples of superoxide dismutase with a lower limit of measurements of about 10 mg. It can be adapted to measure the levels of superoxide dismutase in various crude biological samples.
When is Serum Albumin Worth Measuring?
Authors: Whicher J , Spence C
Published: February 2014

This paper critically examines the usefulness of serum albumin measurement in the light of current laboratory practice and knowledge of the pathophysiology of albumin metabolism.

The main conclusions and recommendations are as follows:

Albumin measurement forms a limited, but useful part of the investigation of liver disease; a normal serum albumin concentration makes the diagnosis of cirrhosis unlikely, while a low level in viral hepatitis suggests either severe hepatocellular damage or other complications. Albumin measurement is essential in selecting patients for, and in determining the amount and frequency of, albumin replacement. Serum albumin concentration provides a useful indication of prognosis in myeloma. In the long-term management of patients undergoing enteral or parenteral nutrition, serum albumin concentration is one of several parameters which, together, are useful in predicting the outcome of treatment. (v) The serum albumin concentration may provide a clue to the aetiology of unexplained oedema. Serum albumin measurement is useful in indicating the level of ionised calcium and of unbound unconjugated bilirubin.
Blood Serotonin Levels in Adults, Autistic and Non-Autistic Children—With a Comparison of Different Methodologies
Authors: Badcock N R , Spence J G , Stern L M
Published: February 2014

Recent interest in conditions associated with increased blood serotonin level has highlighted the need for consistency between assay methods to allow for more accurate delineation of serotinin variables. To this end, comparison was made between a spectrofluorimetric technique frequently used in the past and two potentially more specific high performance liquid chromatographic procedures. Normal ranges and diurnal variations for blood serotonin in adults, normal, autistic children and children with developmental dysphasia were also determined. No significant difference was found between serotonin level in blood drawn by simultaneous venepuncture and capillary (fingerprick) collection. Whilst there was no evidence of circadian rhythm, seasonal variation with mean blood serotonin levels significantly lower in summer than in two successive winters was suggested. Blood serotonin values in normal children tended to decline with increasing age. No similar maturational effect was apparent in autistic children. The mean level for autistic children in winter was significantly higher than that for normal children in the same season; despite this there was considerable overlap of blood serotonin levels between normal and autistic groups. Serotonin levels determined by the three different methodologies showed a high correlation but differed significantly: caution should be exercised when comparing blood serotonin results where different methods are employed.
The Clinical Use and Measurement of Theophylline
Authors: Rowe David J F , Watson Ian D , Williams John , Berry David J
Published: February 2014

This report reviews the clinical use, metabolism and toxicity of theophylline (Section 1). Current chromatographic and immunoassay methods for theophylline measurement are discussed and practical methods using high-performance liquid chromatography are described (Section 2). Results from the UK National scheme for theophylline quality control and from an experiment to investigate the degree of interference by 1,7-dimethylxanthine in routine assays for theophylline are discussed in Section 3.
Investigation of the Use of Bilirubin Oxidase to Measure the Apparent Unbound Bilirubin Concentration in Human Plasma
Authors: Goldfinch Monica E , Maguire Gerald A
Published: February 2014

An investigation into the use of bilirubin oxidase to measure the apparent concentration of unbound bilirubin in solutions of bilirubin or bilirubin/human serum albumin demonstrated (1) near linearity of oxidation rate with bilirubin concentration up to 16 μmol/L, (2) linearity with respect to enzyme concentration up to 75 mg/L, (3) specificity of the enzyme for unbound bilirubin, as opposed to bound bilirubin, (4) poor precision. Very small absorbance changes leading to poor precision and the potential for interference by conjugated bilirubin meant that the method was unsuitable for patient samples.
An External Quality Assessment Scheme for Total Bilirubin
Authors: Johnson Keith R
Published: February 2014

A regional quality assessment scheme for total bilirubin methods is described. The scheme provides liquid sera at three concentrations and allows method linearity to be assessed. The sera were shown to be adequately stable over the periods of assessment.

An integral part of the scheme is quick feedback of comparative performance between and within participant laboratories.

Data presentation has some novel aspects to it (a) the weekly report shows deviation from the weighed-in value and intra- and inter-laboratory variation (b) the 6-monthly summary gives the average performance of the best three laboratories as achievable precision. There is also dialogue with participants on all aspects of the scheme including the material provided.
Serum Aluminium Measurement by DC Plasma Emission Spectrometry
Authors: Roberts N B , Williams P
Published: February 2014

A serum aluminium assay has been established using a DC plasma emission spectrometer and calibration with serum based standards.

The assay is linear between 0·20 and 18·0 μmol/L aluminium. The procedure gives good analytical recovery and precision. The assay was validated by comparison(s) with an electrothermal atomic absorption (ETAAS) procedure which showed good agreement.

Serum aluminium concentrations have been compared in normal individuals, in undialysed chronic renal failure patients with or without aluminium hydroxide treatment, and in dialysed patients treated with oral aluminium hydroxide. Non-dialysed patients had higher serum aluminium concentrations if treated with aluminium hydroxide. Haemodialysis patients had the highest serum aluminium concentrations whilst those on peritoneal dialysis had levels similar to those of the non-dialysed chronic renal failure group.
Essential Considerations in the Provision of Near-Patient Testing Facilities
Authors: Marks Vincent
Published: February 2014

(1) Near-patient testing (NPT) is both practicable and in some situations desirable.

(2) Like all new technologies its apparent simplicity often belies its complexity and masks the need for attention to detail in order to achieve optimum effects and avoid disasters.

(3) Though technically unskilled individuals are capable of using it, they must undergo training in the elements of safety, sample collection, quality control, quantitation and documentation before being authorised to provide analytical services for patients.

(4) Health Authorities should be encouraged to adopt a policy of integration of NPT and clinical laboratory services in order to reduce unplanned use and abuse of NPT facilities which is not only wasteful and divisive, but also dangerous. This has recently been emphasised in the United Kingdom by the release of a Hazard Notice (HN (Hazard) (87) 13) by the Department of Health and Social Security.

The experienced clinical biochemist will, by virtue of training and experience, usually be the most suitable person in a Health District to advise on many of the issues involved in NPT. It should therefore, be the responsibility of laboratory staff to work with management, clinical, and nursing staff to: choose appropriate sites for the various levels of service to be provided to meet a clinical need; select the equipment and reagents to be employed; provide training in the use of the apparatus, quality control and safety; authorise accredited users and oversee the quality assurance programme.

(5) Laboratory staff will need to involve themselves closely in the financial implications of NPT both for the laboratory's benefit and that of clinical practice within the hospital and/or community as a whole.
An Isotonic Potassium Chloride Liquid Junction Minimises the Effects of Ionic Strength, Protein and Haematocrit on Ionised Calcium Measurement
Authors: Payne R B
Published: February 2014

When the reference electrode liquid junction of a Nova 2 analyser was changed to isotonic potassium chloride, increasing the ionic strength of aqueous solutions containing a constant total calcium concentration had a negligible effect on measured ionised calcium. In contrast, measurements using hypertonic potassium chloride, hypertonic sodium formate and isotonic sodium chloride liquid junctions showed significant sample ionic strength effects. Interferences by sample protein concentration and haematocrit were marked with hypertonic, but negligible with isotonic junctions. Ionised calcium values in samples containing 25 mmol/L acetate, bicarbonate, β-hydroxybutyrate, lactate or pyruvate were all lower by 6–7% with an isotonic than a hypertonic potassium chloride junction. Thus, anions that replace bicarbonate during metabolic acidosis have a similar effect on residual liquid junction potential. The clinical usefulness of an isotonic potassium chloride liquid junction needs to be evaluated.
Biological Variation of Serum and Urine Creatinine and Creatinine Clearance: Ramifications for Interpretation of Results and Patient Care
Authors: Gowans Elizabeth M S , Fraser Callum G
Published: February 2014

Analytical and intra- and inter-individual components of variation were assessed over a 40-week period in 15 apparently healthy subjects, seven men and eight women, for serum creatinine, urine creatinine expressed in both concentration and output terms, and creatinine clearance, both uncorrected and corrected to standard surface area of 1·73 m2. Serum creatinine, even when considered separately for men and women, has marked individuality, and conventional population-based reference ranges are consequently of limited value. In contrast, urinary creatinine and creatinine clearance have less individuality, and reference ranges are more useful. Desirable analytical standards are not attained for serum creatinine assays, but are achieved for urine creatinine and clearance determinations. Creatinine clearance is, therefore, the favoured first-line test for initial assessment of patients. However, the small critical difference required for two serum creatinine results to be significantly different, and the comparatively large critical difference for clearance, make serial serum creatinine assays more useful for monitoring individuals.
An Assessment of the Value of Biochemical Fetoplacental Function Tests in Detecting Intrauterine Growth Retardation
Authors: McDowell B , Evans S E , Weaver J B , Little D
Published: February 2014

Four serum biochemical fetoplacental function tests (HPL, unconjugated and total oestriol and AFP) were used to screen for intrauterine growth retardation in 793 patients attending an antenatal clinic. The birthweight corrected for sex, birth ranking and maternal size was used as an index of growth. The sensitivity and specificity of each test was calculated at varying cut-off points and plotted as ‘Receiver Operator Curves’. HPL is clearly better than the oestriols or AFP with 80% sensitivity in detecting birth weights of less than the 5th centile when the 25th HPL centile is used as the cut-off point. However, the sensitivity of HPL is sufficiently low to make the value of screening questionable, particularly since 40% of all growth retarded infants were in mothers who did not attend antenatal clinic for screening and 25% of all growth retarded infants were detected by clinical examination.
A Sensitive Direct Radioimmunoassay for Assessing D-Norgestrel Levels in Human Plasma
Authors: Watson T G , Stewart B J
Published: February 2014

A direct radioimmunoassay was developed for assessing the levonorgestrel levels in human plasma without the need for heat, chromatographic or extraction pretreatment. D-norgestrel-3 (0-carboxymethyl)-oximino-BSA conjugate was used to raise antibodies having a low binding affinity towards other endogenous steroids. The rivanol-purified antiserum after dilution was used as the binding protein. The direct assay of levonorgestrel in human plasma was then compared to an extraction procedure. Lower intra-assay variability was shown by the direct assay when compared to the extraction method used at a sensitivity level of 0·15 nmol/L. The performance of the direct assay in quality control tests was more than favourable when compared with the extraction procedure. An examination of the effects of protein concentration on extraction efficiency was carried out together with an assessment of levonorgestrel levels in plasma in eight normal healthy women currently taking oral contraceptives and eight women who were not, at 0–24 h after the ingestion of 150 μg of D-NG and 30 μg of ethynyl oestradiol.
An Automated Solid-Phase 17α-Hydroxyprogesterone ELISA Method Using a Microtitre Plate
Authors: Yeo K H James , Elder Peter A , Lewis John G
Published: February 2014

We report an automated ELISA method for the measurement of 17α-hydroxyprogesterone in plasma samples. A rabbit antiserum raised against 17α-hydroxyprogesterone-3-(O-carboxymethyl)oxime-bovine serum albumin is used for the assay and a homologous competitor 17α-hydroxyprogesterone-3-(O-carboxymethyl)oxime-bovine thyroglobulin is coated onto a microtitre plate. A goat anti-rabbit IgG-horse radish peroxidase is used as a probe for this solid-phase assay. The assay exhibits good sensitivity, precision and accuracy. The method is used routinely for the management of patients with congenital adrenal hyperplasia.
Quality of Performance of Assays for Maternal Serum Alphafetoprotein in the United Kingdom: Evidence from the UK External Quality Assessment Scheme 1980–87
Authors: Seth J , Hanning I , Bacon R R A , Hunter W M
Published: February 2014

Between-laboratory agreement in the UK EQAS for maternal serum alphafetoprotein has improved steadily since 1976 and the geometric coefficient of variation is now 8 to 9% at levels of 50 to 150 kU/L. The use of a common standard and commercial assay kits appear to have contributed to this trend. Within-laboratory performance is also generally good, about 50% of participants maintain a bias of less than 5%, together with a scatter of the bias of less than 10%. These data indicate that the quality of assay performance is adequate for the requirements of screening programmes for open neural tube effects. The improvement in laboratory performance is such that between-laboratory agreement is better expressed in kU/L than as multiples of the median. Errors in interpretation of clearly normal or abnormal results appear to be rare (0·4%), and contribute little to overall false positive and negative rates. However. they assume significance as most arc due to avoidable errors.
Early Diagnosis of Myocardial Infarction by Timed Sequential Enzyme Measurements
Authors: Collinson P O , Rosalki S B , Flather M , Wolman R , Evans T
Published: February 2014

Serum samples from patients admitted to a coronary care unit with a history of acute chest pain suggestive of myocardial infarction in the previous 12 h were obtained on admission and at 6 and 12 h, thereafter. Creatine kinase (CK), CK-MB isoenzyme, CK-MM sub-bands, myoglobin, and lactate dehydrogenase (LD) isoenzymes were examined. Changes were evaluated in relation to the diagnosis obtained from clinical examination, serial electrocardiography and ‘routine’ cardiac enzymes (CK, aspartate transaminase and alpha-hydroxy butyrate dehydrogenase daily for 3 days following admission). The slope of the logarithms of CK, CK-MB activity and CK-MB concentration in the early post infarct period fully distinguished between infarct and non-infarct patients. Measurement of myoglobin and lactate dehydrogenase isoenzymes was less sensitive. Serial estimation of CK-MM sub-band patterns allowed the time from infarction to be estimated. Serial estimation of CK in the 12 h following admission can be substituted for conventional daily enzyme estimations for the diagnosis of acute myocardial infarction in patients with onset of chest pain within the previous 12 h. This could reduce laboratory and in-patient costs.
The Acidification Response of Normal Subjects to Ammonium Chloride Using a 3-Day Loading Test
Authors: Fry Ian D R , Cusick Paulette E , Alston William C , Montgomery Bruce , Tovey John E
Published: February 2014

The acidification response to NH4 Cl loading (0·1 g/kg bw/day) was tested in 16 normal healthy subjects in the basal fasting state on Day 4, the subjects having taken the salt daily for the 3 previous days. The response was measured in terms of blood pH and in urine, creatinine, phosphate, pH, titratable acidity, ammonium, net acidity and creatinine clearance. To minimise inter-subject variation the urine values were adjusted to a standard body surface area of 1·73 m2. A normal range for the blood pH of the mean value ±2 SD, encompassed the observed range of values. However, to fit the observed range of acid-base values in urine into the 2 SD range required a logarithmic transformation of the data. Statistical analysis confirmed a significant correlation between blood [H+] net acid secretion, urine titratable acidity and ammonium. Urine net acid secretion was positively correlated with urinary phosphate, titratable acidity and ammonium.
Serum Fructosamine Does Reflect Levels of Glycated Serum Albumin in Insulin-Dependent Diabetics
Authors: Lloyd D R , Marples J
Published: February 2014

Fructosamine was measured in the serum of 62 patients with insulin-dependent diabetes (IDD) and 32 non-diabetics and the results compared with glycated albumin levels (GSA) measured using the affinity medium Cibarcron blue F3GA.

Good correlations were found both for the IDD patients ( r=0·93) and the combined group of IDD plus non-diabetics ( r=0·95). We conclude, that fructosamine measurements accurately reflect GSA concentrations, and, therefore, provide a practical method for assessing intermediate term glycaemia in IDD.
HPLC Analysis of 6-Mercaptopurine and Metabolites in Extracellular Body Fluids
Authors: Rudy J L , Argyle J C , Winick N , Van Dreal P
Published: February 2014

A convenient HPLC assay, which allows for the simultaneous measurement in extracellular fluids of 6-mercaptopurine and four of its metabolites, 6-thioguanine, 6-mercaptopurine riboside, 6-thioxanthine and 6-thiouric acid is described. Solid phase extraction allows for the clean isolation of analytes from plasma, urine or cerebrospinal fluid. The simultaneous determination of 6-mercaptopurine and some of its major metabolites in extracellular fluids may contribute to the monitoring of patient compliance, bioavailability, and individual variation in metabolism and absorption.
Serum Free Thyroxine and Free Tri-Iodothyronine in Normal Children
Authors: Butler J , Moore P , Mieli-Vergani G , Moniz C
Published: February 2014

Serum free thyroxine (fT4) and free tri-iodothyronine (fT3) were measured in 138 normal school children, adolescents and their younger siblings, whose ages ranged from 3 months to 18 years. Mean fT4 concentration (16·8 pmol/L) was similar to the adult mean concentration of 17 pmol/L and all the values were within the adult reference range. At all ages the fT3 range was considerably higher than the adult reference range and the overall mean fT3 concentration (8·3 pmol/L) was at the upper limit of normal in adults. In subjects aged 13–18 years the mean fT4 concentration was higher and the mean fT3 concentration lower than in children aged 0–12 years. The reasons for these differences are not known, but the data obtained provide a useful guide to the interpretation of serum free thyroid hormone measurements in children.
Urinary C-Peptide: A Useful Tool for Evaluating the Endogenous Insulin Reserve in Cohort and Longitudinal Studies of Diabetes in Childhood
Authors: de Beaufort C E , den Boer N C , Bruining G J , Eilers G A M , van Strik R , Weterings T
Published: February 2014

Increasing research into the remission phase of type I diabetes mellitus stresses the importance of a non-traumatic and reliable method for the evaluation of endogenous insulin production. We compared 24-h urinary C-peptide excretion (UCE) with plasma C-peptide values before and after stimulation with 1 mg glucagon in 24 type I diabetic children. Fasting plasma C-peptide values and stimulated plasma C-peptide values showed a linear correlation with 24 h UCE. Mean plasma C-peptide levels correlated inversely with the exogenous insulin dose. A slightly better correlation was found between the exogenous insulin dose and 24 h UCE. Control data of 24 h UCE were obtained from healthy siblings. A linear correlation with age was found up to 10 years of age above which UCE values seem to reach a plateau. This effect of age, as well as the frequency of sampling was taken into account in the derivation of 95% reference intervals for UCE. The measurement of 24 h UCE appears to be a useful parameter to assess endogenous insulin production in diabetic children, provided that age is taken into account.
Antenatal Diagnosis of Neural Tube Defects Using a Coated Bead Immunoassay for Acetylcholinesterase in Amniotic Fluid
Authors: Mehta Shobhna , Spencer Kevin
Published: February 2014

The development and validation of a coated bead immunoassay for amniotic fluid acetylcholinesterase is outlined. The assay has good precision (between assay CV of 6·8% within the normal range), and is linear up to 250 arbitrary units/L. The clinical validity of this assay has been assessed using a panel of amniotic fluid samples from normal and abnormal pregnancies. At an assay cut off level of 200 arbitrary units/L, all cases of neural tube defect-affected pregnancies were identified and the number of false positives was very small. False positives resulted from severe blood staining of the amniotic fluid. Since the monoclonal antibody used recognises red cell membrane acetylcholinesterase and the stored amniotic fluids had been frozen and thawed a number of times, the extent of this problem needs to be further assessed using freshly collected samples. The performance of this assay was found to be superior to the differential inhibitor colorimetric method and close to that of the electrophoretic procedure. The quantitative nature of the assay and the independence from operator technique makes it a useful adjunct to the measurement of amniotic fluid AFP in the prenatal diagnosis of neural tube defects.
Neuroblastoma—When are Urinary Catecholamines and Their Metabolites ‘Normal’?
Authors: Worthington D J , Hammond E M , Eldeeb B B , Green A , Addison G M , Jones P H Morris , Mann J R
Published: February 2014

The overproduction of catecholamines and their metabolites is a well recognised feature of neuroblastoma. Published data are scarce for their urinary excretion in children with neuroblastoma and in ill children in whom this diagnosis may be considered. We have determined a graphical upper reference limit for total catecholamines, total metadrenalines and HMMA in urine, expressed as a ratio to the creatinine concentration, for a group of 174 children with neuroblastoma and 704 hospitalised children with other disorders. This graph has been determined by examining the overlap region between the results for the two groups of children and avoids the irregularities caused by statistical outliers. The sensitivity and specificity of the individual tests indicate that total catecholamines is marginally the best single test to perform when trying to diagnose neuroblastoma, with the best clinical sensitivity being achieved by examining both total catecholamines and HMMA. Only two of the 174 children with neuroblastoma would not have been detected using these two tests. Total metadrenalines did not appear to add any further information and could be dropped from the repertoire in favour of the other two measurements.