bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of 5-Fluorouracil in Human Plasma by High-Pressure Ion-Exchange Chromatography
Authors: Hsu Lorna S F , Marrs T C
Published: February 2014

A method has been developed for the measurement of 5-fluorouracil by isocratic high-pressure ion-exchange liquid chromatography. Chlorpheniramine was added to the standards and samples before extraction with 16% isopropanol in ethyl acetate. The extracts were then chromatographed using a mobile phase of 0·014 mol/l ammonium dihydrogen phosphate buffer, pH 3·5, at a flow rate of 1 ml/min. Ultraviolet detection at 266 nm was used, and quantitation was by measurement of the peak height ratios of 5-fluorouracil to chlorpheniramine.
Oestrogen Determinations in Urine from Pregnant Women: A Review of Six Years' Quality Assessment in the United Kingdom
Authors: Oakey R E
Published: February 2014

Since 1974 laboratory performance in the estimation of oestrogens in urine from pregnant women has been assessed in about 150 laboratories by analysis, at intervals of three weeks, of samples of freeze-dried urine. An index of discrimination, Δ (= 2·7 SD derived from results reported on six pairs of duplicates), was calculated for each participant laboratory to provide a measure of between-batch precision. There has been a gradual improvement in laboratory performance assessed in this way. Initially, only 45 % of the participants were able to discriminate between two 24-hour urine samples, differing in oestrogen by at least 20 μmol, when analyses were performed on different days. In the final period ending March 1980, 61 % of participants achieved this standard.
Clinical and Laboratory Evaluation of Four Methods of Assessing Free Thyroxine Status in Thyroid Clinic Patients
Authors: Fyffe J A , Ayoub L , Cohen H N , Turner J G , Thomson J A , Ratcliffe J G
Published: February 2014

The clinical value of four laboratory methods of assessing free thyroxine status was compared in 82 consecutive patients newly referred to a thyroid clinic with suspected thyroid dysfunction. The methods of determining free thyroxine used were: (1) free thyroxine index using a thyroid hormone uptake test (FTI (THUT)); (2) a free thyroxine index using thyroxine binding globulin (FTI (TBG)); (3) a kinetic radioimmunoassay (Immophase); and (4) an equilibrium dialysis method. The definitive thyroid status was evaluated by a combination of clinical assessment (including Wayne index), routine tests of thyroid function (total T4, T3, TSH, and TRH tests where appropriate), and by therapeutic trial in one case. The diagnostic efficiency of the tests was markedly dependent upon the method of determining the reference range for euthyroid patients. Best efficiency for each test was achieved using an amended range after excluding outliners. Test efficiency was then 97·6 % for FTI (THUT) and the kinetic RIA and 96·8% for FTI (TBG). Misclassification by one or more of these tests occurred in only four patients (mild hypothyroid, euthyroid on phenytoin, euthyroid on oral contraceptive and valium, T3 hyperthyroid). In contrast, free T4 by equilibrium dialysis was much less efficient (86·6%) and was technically the most complex. Overall the kinetic T4 RIA provided similar diagnostic information to the indirect indices. However, further studies of cost benefit in settings other than a thyroid clinic are required to assess whether this method might replace total T4 and/or FTI as a first-line test of thyroid function.
A Comparison of Some Methods of Phenotyping the Plasma Cholinesterase Variants Using Benzoylcholine as Substrate
Authors: Whittaker Mary , Britten Judith Josephine
Published: February 2014

Five differential inhibitors of plasma cholinesterase have been compared using benzoylcholine as substrate. None of the inhibitors (dibucaine, NaF, NaBr, NaCl, or pancuronium dibutyryloxy bromide) could be used singly to resolve all the variants. Better resolution was obtained when two inhibitors were used in conjunction. Clear differentiation of all six genotypes was obtained only with the combined use of pancuronium dibutyryloxy bromide and sodium fluoride. The limitations of some of the parameters are discussed.
Interference by Polar Metabolites in a Direct Radioimmunoassay for Plasma Aldosterone
Authors: Jones Julia C , Carter Graham D , Macgregor Graham A
Published: February 2014

The CIS Aldoctk-125 kit, a direct radioimmunoassay for plasma aldosterone, has been compared with a conventional technique involving solvent extraction. Results given by these two methods were poorly correlated (r = 0·445, n = 103), the direct assay giving higher values, particularly in patients being dialysed for renal failure. When the kit was modified to include an extraction step, results correlated well with those of the standard method (r = 0·952, n = 60).

These observations suggested interference from polar metabolites. The possibility that glucuronides were responsible was investigated by measuring plasma aldosterone before and after hydrolysis with β-glucuronidase. Higher post-hydrolysis values confirmed the presence of glucuronides in plasma from normal subjects and patients with renal failure. Preliminary chromatographic studies on plasma from nine dialysis patients indicated the presence of tetrahydroaldosterone 3-glucuronide, and it is thought that this metabolite might contribute to the high values obtained with the direct assay.
Ratio of Thyroxine to Thyroxine-Binding Globulin
Authors: Cusick C F
Published: February 2014

The thyroxine:thyroxine-binding globulin ratio in serum (T4:TBG) has been proposed as a measure of thyroid status unaffected by altered binding protein levels. Here 320 apparently euthyroid patients are used to derive euthyroid ranges for serum thyroxine concentrations at specific TBG levels. These ranges are compared with those predicted by a T4:TBG reference range derived from the same patient data. The comparison suggests that the ratio would give false positives for hyperthyroidism at low TBG levels and false negatives at high TBG levels. To overcome this the use of graphical reporting of results or the relation of patient results to empirical reference ranges appropriate to the TBG level is suggested.
Gel Isoelectric Focusing and IgG Index for Demonstration of Intrathecal IgG Synthesis in Neurological Disorders
Authors: Van Bergh Frank A J T M , Roos Raymund A C
Published: February 2014

Cerebrospinal fluid (CSF) and serum were obtained from 37 patients with multiple sclerosis and from 112 patients with various other neurological diseases, and the concentrations of IgG and albumin were quantitated immunochemically. Simultaneously, isoelectric focusing (IF) was carried out for the detection of CSF-specific oligoclonal bands in the alkaline region.

CSF-specific components were found in 51 patients by IF, the estimated number of which correlated significantly (Rs = 0·733, p<0·0001) with the value of the IgG index. In addition, six patients without CSF-specific abnormalities on IF had an increased IgG index (>0·70). In two of them this increase is, in all probability, false-positive; three others showed fully identical IF bands in both CSF and serum. On the other hand, 13 of the same 51 patients showed a normal IgG index (<0·70) although CSF-specific components were detectable on IF.

These results confirm the superiority of IF over the immunochemical quantitation of albumin and total IgG for the evaluation of immune reactivity in the central nervous system.
Drug Analyses in Poisoned Patients—The Need to Be Specific
Authors: Stewart M J
Published: February 2014

Methods for the qualitative determination of drugs in blood and urine which have been used over the past 20 years have on several occasions given rise to incorrect interpretation due to their lack of specificity, which has resulted in falsely high values being reported for commonly requested drugs. Modern methods provide an opportunity to ensure specificity in the future but analysts must continue to be aware of the potential pitfalls. Examples of non-specificity in colorimetric, UV spectrophotometric, and immunological techniques are described and the clinical implications are demonstrated.
Neuropetides and Cerebrospinal Fluid
Authors: Burbach J Peter H
Published: February 2014

Neuropeptides are present in brain tissue as well as in cerebrospinal fluid. Studies from a variety of disciplines have demonstrated that neuropeptides have neuromodulatory activities. Such activities are apparent in the involvement of neuropeptides in the regulation of adaptive, autonomic, and endocrine functions of the brain. Neuropeptides exert their neuromodulating influences by acting as neurotransmitters or as neurohormones. The neurotransmitter function of neuropeptides is associated with their synthesis in situ in brain and anatomical distribution via neuropeptidergic fibre systems. The presence of such neuropeptides in cerebrospinal fluid may be due primarily to drainage into the cerebrospinal fluid compartments, their levels being a reflection of cellular processes such as biosynthesis, release, and metabolism. On the other hand, neuropeptides functioning as neurohormones may be actively delivered into the cerebrospinal fluid from central or peripheral sources. They employ the pathways of cerebrospinal fluid circulation as avenues of transport, and their cerebrospinal fluid levels may be functionally related to neurohormonal activity. In either case the cerebrospinal fluid levels are informative on the neuropeptide climate in brain; thus their determination is meaningful. The methodology for the sensitive and specific determination of neuropeptides is becoming available. Determination of neuropeptides may well be of diagnostic value in clinical practice.
Total, Ultrafiltrable, Dialysable and Ionised Calcium Measurements in Randomly Selected Samples Compared with Clinical Diagnoses
Authors: Toffaletti John
Published: February 2014

Total, ultrafiltrable (Worthington ‘Ultrafree’), dialysable and ionised (Orion SS–20) calcium levels were measured in 110 serum samples selected randomly from patients for whom total calcium was ordered as a routine test. The available medical records were used to categorise most of the 86 patients as a guide to determining if the calcium results were appropriate to the diagnosis. Total calcium measurement was precise and reliable but was affected by the albumin level. Dialysable calcium measurement was good for diagnostic purposes and was not affected by albumin. Of 25 patients with apparently normal calcium metabolism, six had elevated ultrafiltrable calcium results. Ionised calcium measurement required the most time and sample and offered few, if any, clear advantages in diagnosis over the other free calcium tests. Further improvements in ionised calcium measurements appear to be needed.
Influence of Sampling Time on Salivary Oestriol Concentrations in Pregnant Women
Authors: Cusick Paulette E , Truran Peter L , Read Graham F , Alston William C
Published: February 2014

Saliva specimens were collected at weekly intervals during the third trimester of 61 uncomplicated pregnancies. Oestriol concentrations, measured in samples collected in the early morning from fasting, recumbent subjects, were used to construct a provisional normal range. This proved to be higher than the corresponding normal range reported from another laboratory applying the same method to samples obtained at random from a different population of ambulant subjects. Interlaboratory variation in the assay of salivary oestriol was not sufficient to account for the difference in normal range. It is concluded that consideration should be given to the timing of sample collection if salivary oestriol concentration is to be monitored as a possible means of assessing fetoplacental function. A normal range for salivary oestriol concentration versus gestational age obtained from women sampled randomly may not be appropriate for monitoring patients with ‘at-risk’ pregnancies who are normally bed-rested.
A Kinetic Fluorimetric Assay for the Measurement of Angiotensin-Converting Enzyme in Human Serum
Authors: Maguire Gerald A , Price Christopher P
Published: February 2014

The development and assay performance of a direct kinetic fluorimetric assay for angiotensin-converting enzyme is described. It is based on the substrate developed by Carmel et al. ( Clin Chim Acta 1979; 93: 215–20), and applied to a microcentrifugal analyser with fluorescence optics. The method is sufficiently sensitive and precise to detect both normal and pathological activities; the method is linear up to at least three times the upper limit of the reference range. The method correlates well with an established method. Because of interference, the method is unsuitable for use with icteric or haemolysed samples.
Interference in Colorimetric Reactions for Measuring Hydrogen Peroxide
Authors: James D R , Price C P
Published: February 2014

We describe evidence that serum samples from patients with chronic renal failure possess a constituent that interferes with the measurement of uric acid when using a method employing uricase with peroxidase-assisted detection of the hydrogen peroxide generated. The interference is also reflected in reduced recovery of both hydrogen and sarcosine when added to serum from patients with chronic renal failure. The interferent may be protein in nature or protein bound, as the poor recovery of hydrogen peroxide is seen in patients' serum before and after haemodialysis.
Determination of HDL-Cholesterol Using 2,4,6-Tribromo-3-Hydroxybenzoic Acid with a Commercial CHOD—PAP Reagent
Authors: Trinder Paul , Webster David
Published: February 2014

The Boehringer one-component high-performance cholesterol oxidase reagent has been modified by the inclusion of 2,4,6-tribromo-3-hydroxybenzoic acid (TBHBA) to give a fourfold increase in sensitivity to a molar absorbance of ≈ 29 000 with respect to cholesterol. The resulting reagent system is particularly suitable for the determination of plasma HDL-cholesterol for which a reagent of high sensitivity is required. A simple method of bromination avoiding the use of elemental bromine is used to prepare TBHBA. The modified reagent system has been found to have good within- and between-batch precision and has shown itself to be reliable and trouble-free.
The Preparation and Characterization of Alkaline Phosphatase—Thyroxine Conjugates and Their Use in the Enzyme Immunoassay of Thyroxine
Authors: Eruk A A , Washington R J , Laing I
Published: February 2014

Alkaline phosphatase from calf intestine was conjugated to thyroxine using cyanuric chloride, glutaraldehyde and 1-cyclohexyl-3(−2 morphoinoethyl)-carbodiimide as coupling reagents. The conjugates produced were studied for incorporation of thyroxine, retention of enzyme activity and immunoreactivity in a thyroxine radioimmunoassay system against a range of thyroxine antisera. The use of these conjugates in thyroxine enzyme immunoassay was studied using second-antibody separation. Comparison of the results with radioimmunoassay data was satisfactory and indicates the potential of these conjugates for thyroxine immunoassay. The use of cyanuric chloride as a coupling reagent was unsatisfactory, but good results were obtained with glutaraldehyde. Although satisfactory immunoreactivity of carbodiimide conjugates was observed in a radioimmunoassay system, these results were not reflected in the enzyme immunoassay systems studied.
Improved Performance of Plasma Gonadotrophin Assays Using Common Reagents and Assay Protocols: Evidence from the UK External Quality Assessment Scheme
Authors: Hayes Margaret , Ferguson K M , Jeffcoate S L , Bacon R R A , Seth J
Published: February 2014

Radioimmunoassay kits prepared in the Chelsea Hospital for Women for follicle stimulating hormone (FSH) and luteinising hormone (LH) have been used in 26 UK laboratories for over 2 years. Data from the UK External Quality Assessment Schemes for FSH and LH have been used to provide an independent assessment of the performance of these kits over a 12-month period.

For both analytes, users of the kits were found to have:

a low variability of the bias, implying good within-laboratory, between-assay precision; a lower between-laboratory, within-sample geometric coefficient of variation than users of ‘own’ methods, implying better between-laboratory agreement; method bias that did not differ significantly from laboratories using ‘own’ method protocols.

This survey indicates that a non-commercial organisation can produce immunoassay kits that improve the quality of FSH and LH assays generally available.
Albumin Analysis in Serum of Haemodialysis Patients: Discrepancies between Bromocresol Purple, Bromocresol Green and Electroimmunoassay
Authors: Wells F E , Addison G M , Postlethwaite R J
Published: February 2014

The analysis of serum albumin by bromocresol purple (BCP), by bromocresol green (BCG), and by electroimmunoassay (EIA) has been compared in a mixed group of 100 hospital patients. Good agreement between the immunochemical and BCP methods, but a positive bias with the BCG method led to routine use of the BCP method. In a group of 19 paediatric patients on chronic haemodialysis the mean BCP-albumin was found to be lower than the true albumin, as determined by EIA, whereas the positive bias using the BCG method remained. The difference between BCP-albumin and EIA-albumin in the haemodialysis group varied from 0 to −;13 g/L (mean −7·1 g/L) but was effectively constant for most patients over a 3-month period. Possible mechanisms and necessary further investigations are discussed.
Increased Possibilities for Detecting Drugs by the Toxi-Lab Screening Test
Authors: Plavšić F , Barbarić V , Parag M , Arambašin M , Gjerek J , Stavljenić A
Published: February 2014

The authors have investigated the possibility of detection of over 40 drugs and their metabolites, which are not included in the original list of the Toxi-Lab® reagent set. The data on Rf-values of these drugs and the colours in detecting steps are given.
Low Serum Magnesium Concentration in Paget's Disease of Bone (Osteitis Deformans)
Authors: Taylor W H
Published: February 2014

Approximately 25% of patients presenting with Paget's disease of bone have a low serum magnesium concentration (below 0·74 mmol/L). Metabolic balance studies of 12 normomagnesaemic and seven hypomagnesaemic subjects show that the latter have a significantly more positive balance and a significantly higher net absorption of magnesium than have the former. The urinary output of the two groups did not differ significantly. The serum magnesium and alkaline phosphatase (log) concentrations were significantly negatively correlated, as were the serum magnesium and the daily urinary hydroxyproline (log) output. Low serum magnesium concentrations are thus associated with highly active Paget's disease; they do not arise from increased urinary loss nor from a lowered net absorption of magnesium, but probably from increased uptake by bone. The balance data show that to avoid a negative magnesium balance, the magnesium intake in Paget's disease should be at least 8·0 mmol/day.
Effect of Ethanol on Erythrocyte Acetylcholinesterase Activity
Authors: Haboubi Nuha A , Thurnham D I
Published: February 2014

Erythrocyte acetylcholinesterase (AchE) activity was measured in the blood of 36 alcoholic subjects and 41 healthy volunteers. The mean activity in the alcoholics was significantly lower than that in the control subjects. In vitro experiments showed that ethanol inhibited the AchE activity immediately and in proportion to the concentration of ethanol used. Incubation times up to 6 h did not increase the inhibition significantly. Incubation of normal red cells with ethanol for 15 h, followed by washing, showed also that AchE activity was inhibited by the previous exposure to ethanol and that washing did not reduce the inhibitory effect. The possibility is considered that depressed erythrocyte AchE activity may be an early indication of potential disturbances of the autonomic nervous system. The importance of reporting ethanol intake in patients with organophosphorus poisoning is stressed.
Purple Urine Bag Syndrome
Authors: Stott A , Khan M , Roberts C , Galpin I J
Published: February 2014

Purple pigment extracted from the urinary catheters and collecting bags of two elderly female patients was analysed by a variety of chemical techniques, including mass spectroscopy and nuclear magnetic resonance. Although previous studies identified the pigment as indigo, we failed to confirm this. Our analysis also demonstrated that indicanuria is not a requirement for the production of the pigment and furthermore indicates that the molecular structure of the pigment is either a steroidal or bile acid conjugate.
Thyroid Stimulating Hormone Measurement by an Ultrasensitive Assay during Thyroxine Replacement: Comparison with other Tests of Thyroid Function
Authors: Wheatley T , Clark P M S , Clark J D A , Raggatt P R , Edwards O M
Published: February 2014

Serum thyroid stimulating hormone (TSH) was measured using a highly sensitive enzyme-amplified immunoassay in 37 clinically euthyroid patients receiving thyroxine replacement therapy and compared with other biochemical tests of thyroid function.

A highly significant correlation ( P<0·001) was found between the basal serum TSH and the increase in serum TSH concentration 20 min after the administration of thyrotropin releasing hormone (TRH). The basal serum TSH was negatively correlated with the serum total thyroxine ( P=0·05). When patients results were classified as abnormal or normal many discrepancies were noted between the various thyroid tests. A suppressed serum TSH was found in 65% of patients with a normal serum total thyroxine. However, in patients on thyroxine replacement therapy a basal TSH measured by enzyme-amplified immunoassay provides the same information as a TRH test.
Serum Thyrotrophin in Patients with Destructive Pituitary Lesions Assessed by a Sensitive Immunoradiometric Assay
Authors: Butler J , Cundy T
Published: February 2014

Using a sensitive immunoradiometric assay, serum concentrations of thyrotrophin (TSH) were measured both basally and after intravenous thyrotrophin releasing hormone (TRH) in two groups of patients with destructive pituitary lesions. Group A patients, who had more extensive pituitary hormone deficiencies and biochemical evidence of hypothyroidism at the time of study, had significantly lower mean serum TSH concentrations than the group B patients who were biochemically euthyroid. Basal TSH was below the lowest value seen in a control group of normal subjects in 5 of the 8 group A patients. In all patients TSH increased significantly after injection of TRH; the peak values being significantly correlated with the basal. In contrast to recent studies, which have emphasised other mechanisms in the production of secondary hypothyroidism, our data suggest that inadequate production of immunoassayable TSH is a common cause of secondary hypothyroidism in patients with destructive pituitary disease. Little, if any, additional clinical information is to be gained by measurement of TSH after TRH stimulation in this circumstance.
Burn and Trauma Associated Proteinuria: The Role of Lipid Peroxidation, Renin and Myoglobin
Authors: Gosling Peter , Sutcliffe Anne J , Cooper Mark A C S , Jones Alan F
Published: February 2014

Ten trauma patients and 13 burns patients were studied intensively for the first 36 h and subsequent 6 days post injury in order to investigate the mechanism of trauma and burn associated proteinuria. Burns patient's initial maximum proteinuria occurred between 4 and 8 h post injury, whilst trauma patients showed greatest proteinuria within 4 h. In both groups coexisting myoglobinuria or marked elevation of serum renin activity was not found during the first 36 h. Following admission serum lipid peroxides rose in burns patients reaching a maximum between 2 and 8 h following injury, after which levels fell rapidly; in contrast trauma patient's values were initially within normal limits, but rose sharply after 12 h with peaks occurring between 16 h and 7 days post injury. Some patients within both groups showed a recurrent protein leak 2 to 5 days post injury. The data suggest that myoglobinuria or raised renin levels do not play an important role in trauma associated proteinuria.
A Practical Approach to the Investigation of Amino Acid Disorders
Authors: Edwards M A , Grant S , Green A
Published: February 2014

We have, in this paper, highlighted some of the common problems in amino acid analysis in our experience and listed the possible causes for increases in specific amino acids in urine—together with guidance on appropriate follow-up investigations.
The Measurement of Serum Unsaturated Iron-Binding Capacity in the Presence of Iron-Dextran
Authors: Kind Clive N
Published: February 2014

The standard colorimetric methods most often used for the measurement of serum unsaturated iron binding capacity (UIBC) are subject to gross interference by iron dextran. This paper describes a brief evaluation of an alternative radiometric assay for serum UIBC, based on a commercially available kit method, but incorporating a modification to the manufacturer's protocol. The effects of iron dextran on the assay were determined.
The Middle East External Quality Assessment Scheme for Clinical Chemistry
Authors: Bacchus Robby A , Bullock David G , Noy George A , Whitehead Thomas P
Published: February 2014

The establishment and first 7 years' operation of an external quality assessment scheme for clinical chemistry in the Middle East region are described. The scheme utilises specimens distributed previously in the UK, and the performance of participating laboratories is assessed relative to the UK consensus values, taking account of method. Variance Index scoring has been used to quantitate performance, and there has been an improvement in average scores during the operation of the scheme. There are currently 88 participants, though some laboratories which failed to return results regularly were removed from the scheme. The consensus values from the scheme itself have now been validated, and in future the scheme should operate independently.
Interference by Pro-Apolipoprotein A-I in Apolipoprotein E Phenotyping Using Chemical Precipitation Procedures
Authors: Rawlings A V , Deegan T
Published: February 2014

Lipoproteins of density, d < 1·063, isolated by polyanion-cation precipitation methods, gave isoelectric focussing patterns of apolipoprotein E isoforms by rod-gel electrophoresis which differed from the corresponding patterns obtained from ultracentrifugally-derived very low density lipoproteins. The differences were sporadic and variable but the most common effect was an increased frequency of the E3 isoform. Two-dimensional analyses involving sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Immunoelectrophoresis against anti-apolipoprotein A-I indicated that contamination of precipitated lipoproteins with pro-apolipoprotein A-I was responsible for this phenomenon. It is suggested that two-dimensional techniques should be applied for definitive phenotyping if precipitated lipoproteins are used as source material.
Tea Consumption and Serum Lipids in a Libyan Population in Benghazi
Authors: Sheriff D S , El Fakhri M
Published: February 2014

Libyan subjects are known to consume large amounts of tea. There are reports that consumption of tea is associated with a reduction in serum total cholesterol and LDL-cholesterol. In the present study an attempt has been made to study the effects of tea consumption on 604 local Libyan subjects at Benghazi. The study groups were divided into younger (20–40 years) and older age (41–65 years) groups. It was observed that there was a negative association between tea consumption and serum total cholesterol and LDL-cholesterol concentrations. It appears that tea consumption may be an independent factor influencing serum lipid levels.
Laboratories Respond Differently to the Same Clinical Request
Authors: Broughton P M G , Worthington D J
Published: February 2014

A survey of 19 clinical chemistry laboratories, undertaken to determine what tests would normally be done in response to a number of common clinical requests (e.g. ‘plasma electrolytes please’), revealed wide variations in test patterns. It is suggested that laboratories must bear some of the responsibility for unnecessary testing, and that new strategies are needed to persuade laboratories to adopt more cost-effective test patterns.
Measurement of Human Chorionic Gonadotrophin (hCG): Indications and Techniques for the Clinical Laboratory
Authors: Norman R J , Buck R H , De Medeiros S F
Published: February 2014

The structure of human chorionic gonadotrophin (hCG) is so similar to that of luteinizing hormone (LH) that a variety of assay techniques have been devised to differentiate between these two hormones. The principal indications for measurement of hCG using these methods have not changed greatly over the past decade but the improvements in the sensitivity, specificity and the development of assays for free subunits and metabolic fragments have expanded the use of hCG assays. The review discusses the use of hCG measurement in a routine clinical immunoassay laboratory and emphasizes different requirements for clinical situations.
Gas Chromatography of C19 and 17-Oxogenic Steroids in Urine
Authors: Honour J W , Tsang W M , Patel H
Published: February 2014

17-oxogenic steroids have been analysed by gas chromatography (GC) with capillary column and flame ionization detector. The best separation of steroid products was gained after ethyloxime-trimethylsilyl ether formation. The value of the GC method as a screening procedure for patients with suspected adrenal disease is illustrated in selected cases where the diagnosis was equivocal from data derived by RIA analysis of plasma steroids.
A Multilayer Membrane System for Blood Plasma Isolation for Use in Primary Health Care
Authors: van Oudheusden A P M , Roesink H D W
Published: February 2014

A new membrane–based device is described for the quantitative separation of plasma from blood cells using neither centrifugation nor pipetting. The concentration of cholesterol in the isolated plasma was determined using a newly developed instrument, the Primetest. The results were in good agreement with those obtained in the hospital laboratory.
A Comparison of Analytical Goals for Haemoglobin A1c Assays Derived Using Different Strategies
Authors: Larsen Mogens Lytken , Fraser Callum G , Petersen Per Hyltoft
Published: February 2014

Analytical goals for the performance characteristics of assays of haemaoglobin A1c (HbA1c) have been investigated using different assumptions for generation of estimates, these being based on strategies using data on biological variation and on the clinical use of results. The derived goals are highly dependent on the assumptions made. In general, in monitoring of patients (using results from the same laboratory), the analytical imprecision is the most demanding, whereas bias (inaccuracy) is the most important characteristic when strategies for several centres (laboratories) to achieve similar results are invoked. Goals for analytical quality should be given in a form in which both analytical imprecision and bias (or systematic error) are specified. When several goals are to be considered (for different relevant assumptions), the most demanding should be used.
Renal Insufficiency and Secondary Hyperparathyroidism in Elderly Patients
Authors: Turner Geeta , Brown Richard C , Silver Anne , Seymour Gwyn , Woodhead J Stuart
Published: February 2014

Glomerular filtration rate (GFR) is frequently reduced in elderly people. However, the effect of this on mineral metabolism in this population has received little attention. GFR, serum intact parathyroid hormone (PTH) and vitamin D metabolites were measured in 37 patients admitted to hospital for various reasons. In 20 patients with GFR > 50 mL/min, an elevated serum intact PTH concentration (> 5 · 4 pmol/L) was found in two, while in 17 patients with GFR < 50 mL/min PTH was elevated in 13. One of this group was hypercalcaemic and presumed to have primary hyperparathyroidism. Adjusted calcium was normal in all other patients. Two patients had a low serum 25-hydroxyvitamin D concentration (<9 nmol/L) suggesting vitamin D insufficiency while a further five had a reduced 1,25-dihydroxyvitamin D concentration, four of these having a GFR < 50 mL/min. We conclude that hyperparathyroidism is common in hospitalized elderly patients, particularly in those with mild to moderate renal insufficiency. This may contribute to bone mineral loss in such patients.
Clinical Significance of Phosphate in Calcium Oxalate Renal Stones
Authors: Öhman Sten , Larsson Lasse , Tiselius Hans-Göran
Published: February 2014

We analysed calcium, magnesium, oxalate, citrate, urate and creatinine in urine and calculated risk factors in patients who had formed stones composed of calcium oxalate, and calcium phosphate, alone or as a mixture. Patients producing pure calcium oxalate stones (< 0·1% phosphate) had a higher oxalate, and lower calcium excretion than stone-free subjects and patients forming other stone types. In contrast, patients producing calcium oxalate stones containing phosphate, even in trace amounts (> 0·1%) had no increase in oxalate excretion, but a higher calcium excretion than stone-free subjects. We could not correlate any computed variable (e.g. AP(CaOx) index) to stone composition.

We conclude that pure CaOx stones may be the result of a high oxalate excretion, and that other calcium containing stones may have another and probably more complex aetiology, including primary precipitation of calcium phosphates.
Fractionation of Urine to Allow Desmosine Analysis by Radioimmunoassay
Authors: Starcher Barry , Scott Marti
Published: February 2014

The present study was designed to re-evaluate the radioimmunoassay for desmosine in urine, which is currently used as a measure of elastin metabolism. Using ion exchange chromatography, gel filtration and affinity chromatography it was shown that at least five other compounds in hydrolysates of human urine competed for desmosine in the RIA. Fractionating the urine prior to hydrolysis with acetone removed one of the major contaminants. The other contaminants could subsequently be removed by extracting the urine hydrolysate with a mixture of chloroform/ethanol (60:40). Samples from nine normal adult urines showed that an average of 45% of the RIA competing material in unfractionated urine was not desmosine. The final extracted residue retained all of the desmosine and only 16% of the original solids. The average adult urine contains approximately 50 pmol desmosine/mg creatinine, reflecting a daily turnover of between 3 and 4 mg of elastin per day.
External Quality Assessment of Jordanian Clinical Chemistry Laboratories
Authors: Bilto Yousif Y
Published: February 2014

A two-year study using inter-laboratory surveys has been carried out to assess the analytical quality of Jordanian clinical chemistry laboratories. The study surveyed > 65% (60 laboratories) of Jordanian laboratories using 18 control specimens and covering a total of 15 analytes. Close agreement was obtained between the consensus values and the designated values for analytes which had mean values within the normal range, whereas significantly lower consensus values were obtained for glucose, creatinine, bilirubin and urea in the pathological range. Considerable inter-laboratory variation was observed in Jordan relative to EQA schemes in other countries. This study highlighted several problems in Jordanian laboratories, and stressed the need for a national EQA scheme with an effective means of providing continuous advice, education and training in clinical chemistry.
Nephelometric Determination of Total Protein in Cerebrospinal Fluid and Urine Using Benzalkonium Chloride as Precipitation Reagent
Authors: Shephard Mark D S , Whiting Malcolm J
Published: February 2014

Four different protein precipitants, namely trichloroacetic acid, sulphosalicylic acid, benzethonium chloride and benzalkonium chloride, were used to estimate the total protein concentration in cerebrospinal fluid and urine by nephelometry. Protein determinations for 50 cerebrospinal fluid samples and 100 urine samples were compared with values obtained by a trichloroacetic acid-Ponceau S spectrophotometric method. All methods were correlated well, but total protein results using acid precipitants were usually lower, while results obtained using benzethonium chloride were generally higher, than results obtained by the trichloroacetic acid-Ponceau S method. Anomalous results were obtained for some urine samples with benzethonium chloride, but not with benzalkonium chloride. Assays using benzalkonium chloride as precipitating reagent showed good precision and closest agreement with the trichloroacetic acid-Ponceau S dye-binding method. The use of benzalkonium chloride as precipitant is recommended for automated cerebrospinal fluid and urine protein estimations by nephelometry.
Characteristics of Monoclonal Immunoglobulins That Interfere with Serum Inorganic Phosphate Measurement
Authors: Bowles Shirley A , Tait R Campbell , Jefferson Stephen G , Gilleece Maria H , Haeney Mansel R
Published: February 2014

The measurement of inorganic phosphate using an unmodified acid/molybdate assay is known to be subject to interference when paraproteinaemia exists. This phenomenon, due to precipitation in the reaction mixture, is not common to all paraproteins. We studied sera from 35 patients to determine whether interference in the assay was related to particular electrophysical characteristics of the paraproteins. There were spuriously elevated phosphate concentrations in 48·6% of the sera assayed. This could not be related to a direct effect of light chain type, electrical charge or IgG subclass. No IgA paraproteins were found to cause interference but there were immunoglobulin G (IgG) and immunoglobulin M (IgM) paraproteins in both the ‘interfering’ and ‘non-interfering’ groups. The median paraprotein concentration was similar in both groups but, where interference occurred, the degree increased in line with the paraprotein concentration. Although it does not seem possible to predict which samples will cause interference, it is important that the clinical implications of this problem are appreciated.
Improved Method for Analysis of Glycated Haemoglobin by Ion Exchange Chromatography
Authors: Eckerbom Solveig , Bergqvist Yngve , Jeppsson Jan-Olof
Published: February 2014

The Pharmacia Mono S column for glycated haemoglobin (HbA1c) was compared with Mono S HR 5/5 and three other cation exchange columns to optimize analysis of HbA1c. This column allows a significant decrease in separation time, resulting in a sample throughput of 12 samples per hour.

The choice of parameters for integration of peak areas in the chromatograms is very important for reproducible results. Since pure calibrators of HbA1c are not available, the relative contribution of HbA1c to the total amount of haemoglobin is calculated. We have compared valley-to-valley integration with baseline integration to assess reproducibility. Valley-to-valley integration significantly enhances the reproducibility of the method and is therefore preferable for routine analyses of HbA1c.
Disagreement between the Roche Cobas® Core and Hybritech TANDEM®-E PSA Assays When Measuring Free, Complexed and Total Serum Prostate Specific Antigen
Authors: Tillyer Colin R , Konings Monique , Gobin Philip T , Iqbal Jahangir
Published: February 2014

A comparison of the Roche Cobas® Core and Hybritech TANDEM®-E PSA (prostate specific antigen) assays revealed a large difference in the reactivity of each assay to the separated free and complexed forms of serum PSA in patients with prostatic carcinoma. The Roche assay was relatively much more responsive to the free form, but the Hybritech assay was relatively more responsive to the complexed form and total serum PSA. It is possible that the adoption of a universal standard for PSA will not completely resolve the disagreement between PSA assay on individual patient samples, and the use of separate assays for the free and complexed forms may be necessary for the further clinical development of PSA as a tumour marker.
Measurement of Serum Troponin T, Creatine Kinase MB Isoenzyme, and Total Creatine Kinase following Arduous Physical Training
Authors: Collinson Paul O , Chandler Henry A , Stubbs Peter J , Moseley David S , Lewis David , Simmons Michael D
Published: February 2014

We have compared measurement of cardiac troponin T by enzyme linked immunosorbent assay with creatine kinase MB isoenzyme (CK-MB) concentration measurement in 219 Royal Marine commandos with no evidence of cardiovascular disease who have elevated creatine kinase (CK) produced by arduous physical training. CK was elevated up to 22.6 times and CK-MB mass up to 6.6 times the upper reference limit. Only two commandos had detectable cardiac troponin T, with neither exceeding the upper reference limit of 0.2 μg/L. At decision thresholds optimized for diagnosis of acute myocardial infarction in previous published work, 58.3% of the total CK activity, 13.8% of the CK-MB concentration/CK activity ratio and 1.6% of CK-MB concentration measurements showed elevated values but no elevations in cardiac troponin T occurred. Cardiac troponin T is currently the investigation of choice for the differential diagnosis of patients with an elevated CK due to skeletal muscle trauma to exclude myocardial damage.
A Frame-Shift Mutation of the Androgen Receptor Gene in a Patient with Receptor-Negative Complete Testicular Feminization: Comparison with a Single Base Substitution in a Receptor-Reduced Incomplete Form
Authors: Imai Atsushi , Ohno Tsukasa , Iida Koji , Ohsuye Kazuhiro , Okano Yukio , Tamaya Teruhiko
Published: February 2014

Mutations of the androgen receptor that impair the action of androgens result in abnormal male sexual development. We studied the structure of the androgen receptor gene in a patient with the receptor-negative form of complete testicular feminization and another patient with a receptor-reduced form of incomplete testicular feminization. In the subject with complete testicular feminization, the deletion of a single nucleotide occurred at nucleotide number 1893 at exon 2. The subsequent frame-shift mutation changes the sense of codon 622 from cysteine to a translational stop signal. Codon 622 is in exon 3, so the mutation predicts the synthesis of a truncated receptor that lacks the entire androgen-binding domain. Analysis of a subject with incomplete testicular feminization revealed a single substitution (CGT → CAT) at nucleotide 2675 of exon 7, resulting in the conversion of an arginine at amino acid 840 to a histidine. This mutation in the androgen-binding domain may impair, but not remove, the androgen binding to its receptor. These results suggest that the phenotypes in our subjects are due to the mutations, and that single amino acid substitution and premature termination codon can cause variably severe functional abnormalities.
Increased Serum Lipoprotein(a) Concentrations after Growth Hormone (GH) Treatment in Patients with Isolated GH Deficiency
Authors: O'Halloran Domhnall J , Wieringa Gilbert , Tsatsoulis Agathocles , Shalet Stephen M
Published: February 2014

Fourteen post-pubertal subjects (11 male, 3 female) with isolated growth hormone (GH) deficiency were treated with a low dose (0·125 U/kg for the first 4 weeks and thereafter 0·025 U/kg/week) daily sc GH injection for 1 year. Fasting blood samples were collected at entry into the study and subsequently at 3 monthly intervals for estimation of serum cholesterol, high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol and lipoprotein(a) [Lp(a)]. Serum Lp(a) increased progressively during the treatment period (by analysis of variance) and was 41% higher at 12 months ( P < 0·02) despite the fact that five patients showed little or no change. There was no significant change in any of the other lipid fractions. These observations are of concern as Lp(a) is an independent risk factor for cardiovascular disease and should introduce a cautionary note into the enthusiastic efforts to offer GH replacement to all GH deficient adults.
Rheumatoid Factor in the Serum of Hepatitis C Virus-Infected Patients: An Increase in the Titre during Cold Storage
Authors: Ueda Kazuhito , Nakagawa Toshimasa , Shimizu Akira , Nakajima Hideto , Fukuda Akira , Ohsawa Nakaaki
Published: February 2014

Storage of serum at 4°C elevated the titre of rheumatoid factor (RF) as measured by nephelometry with IgG-coated latex in 12 of 38 specimens positive for hepatitis C virus. Increased RF following cold storage was not detected in HCV-negative sera. Most of the sera showing the cold-dependent elevation of RF had decreased complement hemolytic activity (CH50) after the cold storage. The RF titre elevated by cold storage decreased to the level of fresh serum by the addition of guinea pig serum as a complement supplement in a dose-dependent fashion. Thus, in the serum of some HCV-infected patients, the affinity of RF appears to be weak, and the binding between the RF and IgG coated on latex may be inhibited by the complement components of fresh serum.
Serial Measurements of Serum Creatine Kinase are of Most use in the Exclusion of Acute Myocardial Infarction in Patients with a History of Heart Disease
Authors: Johnston John D , Harvey Christopher J
Published: February 2014

Rapid sequential measurements of serum CK were assessed in the diagnosis and exclusion of acute myocardial infarction (MI) in 94 patients presenting to St Thomas' Hospital, London, with acute chest pain of less than 12 h duration. A blood sample was taken from patients on admission to hospital and then a second sample was taken within 12 h of admission. Serum CK activity was assayed on both samples and Δlog10 (serum CK) per hour calculated to distinguish infarct from non-infarct using a discriminant value of 0.015. Ninety-six per cent of patients with acute MI were diagnosed on the basis of clinical history and electrocardiographic evidence alone, and did not require biochemical confirmation. Serial estimation of serum CK contributed positively towards the exclusion of acute MI in 77% of patients who presented with chest pain and who had a previous history of heart disease, but towards only 11% of cases in the absence of a history of heart disease.
Neopterin Levels in Alcohol-Dependent Patients
Authors: O'Hanlon M , Salter S , Scull D , Labib M
Published: February 2014

Chronic alcohol exposure appears to suppress cell-mediated immunity which may contribute to the high incidence of infections among alcohol-dependent patients. We measured serum neopterin, as a marker of macrophage function and T-lymphocyte activation, in 26 alcohol-dependent patients. The mean serum neopterin in these patients was significantly lower than the mean serum neopterin in matched controls. In those who abstained, the mean serum neopterin at 3 weeks rose and was no longer significantly different from controls. Our findings suggest that alcohol-dependent patients have suppressed macrophage function which may be reversible within 3 weeks of abstention.
Assessment of an Automated Immunoassay Based on Kinetic Interaction of Microparticles in Solution for Determination of Opiates and Cocaine Metabolite in Urine
Authors: Smith F P , Lora-Tamayo C , Carvajal R , Caddy B , Tagliaro F
Published: February 2014

A recently introduced automated immunoassay which is based on kinetic interaction of microparticles in solution (Roche ONLINE), was evaluated for the detection of cocaine metabolite benzoylecgonine (BE) and opiates in human urine. Cross-reactivity for the opiates morphine (100%), codeine (88%), 6-monoacetylmorphine (88%), and morphine 3-glucuronide (72%) was assessed. Analytical recovery evaluated on blank urines spiked with 0, 250, 300, 350, and 500μg/L of morphine and BE ( n = 10), varied from 85·2 to 100·2% for opiates and from 81·4 to 93·1% for the cocaine metabolite. The within-day precision ranged from 1·4 to 4·7% for morphine and from 4·2 to 4·8% for BE. The repeatability of the standards over 1 month was 1·0–3·3% for opiates and 1·7–5·1% for BE, and thus allowing measurements to continue over 30 days without re-calibration. This method compared favourably with the SYVA EMIT d.a.u™ system and gas chromatography/mass spectroscopy (GC/MS) methods.