bluuebunny/crossref_metadata_2025 huggingface dataset:
Urinary Growth Hormone Measurements in Children with Renal Insufficiency
Authors: Turner G , Skinner A , Woodhead J S
Published: February 2014

It has been reported that intrinsic renal factors could affect urinary growth hormone (UGH) measurements. We compared UGH excretion in 21 children aged 4–16 years, with various degrees of renal insufficiency, with that in 10 control subjects aged 5–13 years. We found 100- to 1000-fold elevations in UGH in children with plasma creatinine concentrations > 120 μmol/L (Group A) compared with patients with plasma creatinine concentrations < 120 μmol/L (Group B) and control subjects. UGH excretion (μU) in the three groups was as follows: group A 804–8556 (median 2649); group B 1·0–85 (median 7·5); and controls 2·6–7·3 (median 4·0). Elevated urinary β2-microglobulin levels (μg) were also observed in group A patients: 875–15 400 (median 11 637) as compared with group B, 1·0–104 (median 32) and controls, 3–18·7 (median 8·0). There was no significant difference in albumin excretion between groups A and B though six patients in group B with nephrotic syndrome (NS) excreted significantly more albumin (P < 0·05) than the other 15 patients investigated. Our data show that abnormalities of renal function have a profound effect on growth hormone excretion and we suggest proximal tubular dysfunction as the causative factor. We conclude that UGH measurements do not provide a reliable means of assessment of hypothalamo-pituitary function in patients with renal insufficiency.
Clinical Associations of an Increased Transthyretin Band in Routine Serum and Urine Protein Electrophoresis
Authors: Tormey W P , O'Brien P A
Published: February 2014

The 9697 electrophoretograms performed over an 8 year period were reviewed to identify the frequency and clinical associations of the finding of a prominent transthyretin band in serum or urine, the concentration of which was equal to or greater than a 64 mg/dL protein calibrator. All samples were electrophoresed at a constant 90 V using agarose gels with a barbital buffer pH 8·6 and Ponceau S staining. Reference calibrators were used as standards to identify increased transthyretin bands and the patients' clinical records were subsequently reviewed.

High values were found in 46 patients' sera and a further nine patients' urines representing 0·57% of the total workload. Renal impairment was present in 58% of cases including those with chronic renal failure, the nephrotic syndrome and paraproteinaemia. The high levels were not persistent in three myeloma cases where there was a recovery in renal function following chemotherapy. In some nephrotics, a high urine transthyretin may be secondary to a general hepatic albumin and transport protein synthesis response to severe proteinuria. Why the serum transthyretin was elevated in many other cases remains unclear.
Reducing the Cost of Phenytoin Assays with in-House TDx™ Reagents
Authors: Colbert D L , Turner G J , Gooch J C
Published: February 2014

The Abbott TDx™ is frequently used for therapeutic drug monitoring of phenytoin concentrations, but reagent costs are high. In an attempt to reduce these costs, we investigated the preparation of in-house reagents. A commercial antiserum was available at reasonable cost and the fluorescent tracer was easily prepared. We describe the preparation of these reagents and their application to the TDx™ system. Substantially reduced costs were obtained using the in-house reagents.
The Analysis of Metabolites in Human Sweat: Analytical Methods and Potential Application to Investigation of Pressure Ischaemia of Soft Tissues
Authors: Taylor Richard P , Polliack Adrian A , Bader Dan L
Published: February 2014

A straightforward technique was developed for sweat collection applicable to tissues subjected to external load without introducing distortion of underlying tissues, and for analysis of six metabolites in the collected sweat. Chloride was measured colorimetrically and lactate, urea and urate by enzymatic methods on a centrifugal analyser. Sodium and potassium were measured by flame photometry. The methods showed good precision, recovery and linearity.

To assess the technique sweat was collected: (i) from the sacrum, ischium, forearm and calf in healthy individuals at 32°C for 1 h; (ii) from the sacrum of healthy subjects at ambient temperature for 9 h; (iii) at ambient temperature from the sacrum of a patient with a history of pressure sores. Sweat rates were greater at the sacrum and ischium than the calf or forearm. There were differences in the concentrations of lactate and urea between sites but these were smaller when expressed as amount secreted. Sweat rates were significantly lower in groups (ii) and (iii), but sweat could be collected reliably. This technique has potential clinical application to the investigation of susceptibility to pressure sores.
Seasonal Variation in Serum 25-Hydroxy Vitamin D3 Does Not Affect 1,25-Dihydroxy Vitamin D
Authors: Hine T J , Roberts N B
Published: February 2014

The seasonal variation of serum 25-hydroxy vitamin D3 and 1,25-dihydroxyvitamin D has been investigated. Blood was taken from 27 healthy volunteers, aged 21–44 years old at 3 monthly intervals over a period of 1 year. A scrolling monthly programme with 12 quarterly (3 month) time periods was developed. A summer associated increase in 25-hydroxy vitamin D3 was significantly correlated with but lagged behind by 2 months, the increase in recorded sunlight hours. However, four individuals showed no seasonal rise but maintained constant concentrations throughout the year within the established reference range. Serum 1,25-dihydroxy vitamin D showed marked intra-individual variability with no seasonal pattern although the highest concentration (180 pmol/L) was observed in the winter and no concentration greater than 108 pmol/L in the summer.
Serum Insulin-Like Growth Factor Binding Protein-1 in Pregnant Women: Decreased Concentrations following an Oral Glucose Load
Authors: O'Leary P C , Longley M
Published: February 2014

Serum concentrations of insulin-like growth factor binding protein-1 (IGFBP-1) were measured in men and in non-pregnant and pregnant women. Peak serum IGFBP-1 levels occurred mid-gestation followed by a slight decline towards term. Women with gestational diabetes had higher serum IGFBP-1 concentrations than apparently healthy women at comparable gestation. Following administration of an oral glucose load, serum IGFBP-1 concentrations were decreased within 2 h in men and in pregnant women while IGF-I levels remained constant. These results suggested that IGFBP-1 regulates IGF-I activity in pregnancy in a similar manner to that in the non-pregnant state.
Studies on Red Cell Glucose-6-Phosphate Dehydrogenase: Evaluation of Reference Values
Authors: Yüregir Günes T , Aksoy Kiymet , Arpaci Abdullah , Ünlükurt Isa , Tuli Abdullah
Published: February 2014

The analytical, intra-individual, inter-individual variation and reference values were determined for red cell glucose-6-phosphate dehydrogenase (G6PD). Different procedures for the conditions for storage of red blood cells and the preparation of haemolysates were investigated.

A total of 2170 samples of blood were taken from apparently healthy persons—1212 males and 958 females—from randomly selected villages and city centres in the southern part of Turkey. Analytical variation, intra-individual variation and inter-individual variation were 8·67%, 32·8% and 31·8%, respectively. The mean (SD) for G6PD was 8·6 (3·3) IU/gHb. The index of individuality, 1·03, showed that the reference intervals could be used for diagnostic purposes.

Whole blood or a red cell pellet could be stored in physiological saline for one week at 4°C or −20° with little loss of activity. Two of three different procedures for the preparation of haemolysate gave data that showed no statistical difference and were equally satisfactory.
The Application of a New Highly-Sensitive Radioimmunoassay for Plasma 21-Deoxycortisol to the Detection of Steroid-21-Hydroxylase Deficiency
Authors: Fiet Jean , Villette Jean-Marie , Galons Hervé , Boudou Philippe , Burthier Jean-Michel , Hardy Noah , Soliman Hany , Julien René , Vexiau Patrick , Gourmelen Micheline , Kuttenn Frédérique
Published: February 2014

21-deoxycortisol (21-DF) is a steroid of strictly adrenal origin formed by the 11-hydroxylation of 17-hydroxyprogesterone. This metabolic pathway is minor in normal subjects, in whom basal plasma concentrations range from 0·03 to 0·63 nmol/L and from 0·865 to 1·50 nmol/L after adrenocorticotropic hormone (ACTH; Synacthène Immédiat, Ciba/Geigy, France). However, this metabolic pathway becomes major in 21-hydroxylase-deficient patients: in those who have the classical form of congenital adrenal hyperplasia (CAH) basal plasma 21-DF levels can attain more than 144 nmol/L. The synthesis of two isomers, E and Z, of the 21-deoxycortisol-3-carboxymethyloxime (CMO) hapten enabled us to prepare the corresponding E and Z immunogens by coupling them to bovine serum albumin (BSA), as well as the corresponding iodinated E and Z 21-DF-3-CMO-histamine tracers. We developed a very sensitive radioimmunoassay for 21-DF in plasma by associating an anti-21-DF-3-CMO-BSA-E isomer antibody to an iodinated 21-DF histamine-Z isomer (standard curve IC 50 = 8 pg/tube). This plasma 21-DF radioimmunoassay allowed diagnosis of the classical form of CAH in untreated newborn (basal 21-DF levels greater than 144 nmol/L), as well as the late-onset form (post-ACTH 21-DF levels greater than 11 · 54 nmol/L), and also permitted detection of 21-hydroxylase-deficient heterozygotes of both forms of CAH among the general population (post-ACTH 21-DF levels between 2·02 and 9·52 nmol/L).
Population Screening for Medium-Chain Acyl-CoA Dehydrogenase Deficiency: Analysis of Medium-Chain Fatty Acids and Acylglyeines in Blood Spots
Authors: Bennett Michael J , Ragni Marie C , Ostfeld Robert J , Santer Rene , Schmidt-Sommerfeld Eberhard
Published: February 2014

We have developed methods for the measurement of the medium-chain fatty acids octanoate, decanoate and cis-4-decenoate and the acylglycines n-hexanoylglycine (HG) and 3-phenylpropionylglycine (PPG) in blood spots using gas chromatography and mass spectrometry. Normal ranges were obtained for octanoate and decanoate. HG, PPG and cis-4-decenoic acid were not detected in control blood spots. In blood spots from nine patients (including two newborn) with medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, all metabolites were present in elevated concentrations although PPG was close to the detection limits and there was overlap for octanoate and decanoate. The lack of detection of cis-4-decenoic acid and HG in controls suggests that these are the metabolites of choice for blood spot identification of infants with MCAD deficiency.
Laboratory Blunders Revisited
Authors: Lapworth Ruth , Teal Teresa K
Published: February 2014

Blunders which occurred over a 1 year period in the clinical chemistry departments of two health districts were recorded and categorized according to type and detection stage. A blunder was defined as an incident leading to an incorrect result/set of results either being reported or detected at the final checking-out stage in the laboratory. Of the total of 120 blunders—which is a blunder rate of less than 0·1% of requests—53 (44%) were detected at the final checking-out stage. Blunders detected after the report had left the laboratory were divided into those subsequently picked up by laboratory personnel (23); those detected by clinicians (19); and those by external quality assessment schemes (21). The types of blunder were fairly equally distributed between the booking-in (36), analysis (38), and reporting (35) stages of the laboratory process. A formal review of blunders detected in laboratories is a valuable aid to overall performance.
Calcium Metabolism following Renal Transplantation
Authors: Straffen Anne M , Carmichael DJS , Fairney Angela , Hulme B , Snell M
Published: February 2014

Abnormalities of calcium homeostasis are a recognized feature of end-stage renal disease. The treatment of choice is renal transplantation, but this does not always result in normalization of the biochemical profile. Persistent hypercalcaemia is well documented and our study was undertaken to investigate the status of the calcium regulating hormones in renal patients post-transplantation.

Serum calcium, parathyroid hormone, 1,25-dihydroxyvitamin D (1,25(OH)2D) and osteocalcin concentrations were measured in post-transplant patients. Twenty per cent of the patients had subnormal 1,25(OH)2D concentrations while 55% had biochemical evidence of hyperparathyroidism but only 5% were hypercalcaemic. Time elapsed since transplantation was not correlated with any of the analytes investigated and there was no relationship between persistent impairment of renal function and abnormalities of calcium homeostasis.
Quality Assessment of Urinary Organic Acid Analysis
Authors: Bonham J R , Downing M , Pollitt R J , Manning N J , Carpenter K H , Olpin S E , Allen J C , Worthy E
Published: February 2014

The number of known inherited metabolic disorders resulting in an organic aciduria has increased steadily over the past two decades. Prompt and reliable detection is both clinically and technically demanding but is essential if appropriate treatment is to be undertaken.

This is the first study of laboratory performance in the detection of these disorders to be undertaken in the UK. Some conditions were accurately identified by most laboratories: for example for maple syrup urine disease, 12 of 14 laboratories provided an appropriate response and medium chain acyl-CoA dehydrogenase deficiency was correctly identified by 15 of 17 laboratories. However, accuracy of detection was poorer for other conditions: for example, only eight of 17 laboratories detected tyrosinaemia type 1 and nine of 18 laboratories detected 4-hydroxybutyric aciduria.

The strongest correlation with good performance was obtained by comparison with the extent of peak identification: r=0·62, P=0·002. The need for regular attendance at scientific symposia was also supported by a weaker positive correlation with the average score achieved, P=0·08. Evidence also suggested that some of the laboratories with a low workload performed less well. No significant difference in performance could be demonstrated between the 17 laboratories who used gas chromatography -mass spectrometry and the six participants who used gas chromatography alone.
Low-Density Lipoprotein Particle Size in Type 2 Diabetic Patients and Age Matched Controls
Authors: Stewart Jennifer M , Kilpatrick Eric S , Cathcart Sylvia , Small Michael , Dominiczak Marek H
Published: February 2014

Non-enzymatic glycation of low-density lipoprotein (LDL), and the predominance of small dense LDL particles may together contribute to the increased risk of atherosclerosis in diabetes. We aimed to establish whether the size of LDL particles is related to plasma triglyceride concentration, and to the extent of LDL glycation in type 2 diabetic patients. Sixteen men with type 2 diabetes and 16 age matched non-diabetic controls were studied. LDL size was measured by rapid density gradient ultracentrifugation, and LDL glycation by affinity chromatography. Modal LDL density correlated with plasma triglyceride concentrations in both diabetic and control groups ( r = 0·86, P<0·000, and r=0·76, P<0·0008, respectively). There was no significant difference in these variables between the groups. LDL modal density showed no correlation with HbA1, serum fructosamine or plasma glucose in either group. In the diabetic group the degree of LDL glycation correlated with serum fructosamine ( r = 0·74, P<0·001), HbA1 ( r=0·65, P<0·008), and with plasma glucose ( r=0·64, P<0·008). Our results suggest that, in well controlled type 2 diabetic patients LDL size is independent of short-term glycaemic control but can be predicted by plasma triglyceride concentrations.
Microalbuminuria in Type 2 Diabetic Patients: A Cross-Sectional Study of Frequency, Sex Distribution and Relation to Hypertension
Authors: Friis Thorkild , Pedersen Laurids R , Arnold-Larsen Susanne , Nielsen Dorthe B
Published: February 2014

We studied 112 type 2 diabetic patients. Fourteen patients had frank proteinuria, and 37 of the remaining 98 had microalbuminuria which was more frequent in men than in women ( P<0·02). Hypertension was found in 47 of the patients, equally distributed between sexes. Male diabetics with microalbuminuria had higher systolic blood pressure than diabetics without microalbuminuria ( P<0·02). Body mass index was higher in both sexes with hypertension compared to patients without hypertension. In the hypertensive men plasma C-peptide values were higher compared to patients without hypertension ( P<0·01) irrespective of the presence of microalbuminuria. A positive correlation between blood pressure and C-peptide was found ( P<0·01) in the men. We suggest that gender should be taken into account in the analysis and interpretation of microalbuminuria in type 2 diabetes.
An Improved Method for the Determination of Islet Amyloid Polypeptide Levels in Plasma
Authors: van Hulst K L , Hackeng W H L , Höppener J W M , van Jaarsveld B C , Nieuwenhuis M G , Blankenstein M A , Lips C J M
Published: February 2014

We describe an improved method for the determination of islet amyloid polypeptide (IAPP) levels in plasma. Plasma is first extracted with acid-acetone, followed by a specific and sensitive radioimmunoassay (RIA) for IAPP using rabbit-anti-human-IAPP serum. Recovery of synthetic IAPP from plasma was 82±6% ( n = 16). Standard samples, prepared in ‘hormone-free’ serum, were also extracted with acid-acetone. Displacement curves of serially diluted acid-acetone extracted plasma samples were parallel to the standard curve. The lower detection limit of the RIA was 2·3 ± 0·1 fmol/sample ( n = 5). Intra-assay variations for IAPP concentrations of 4, 17 and 32 pM were 16·3% ( n = 10), 9·2% ( n = 10) and 6·2% ( n = 10); inter-assay variations were 35·9% ( n = 14), 19·9% ( n = 15) and 15·4% ( n = 15), respectively.

Non-stimulated IAPP levels ranged from 2·4 to 12 pM (mean 6±4pM, n = 10) in healthy control subjects. IAPP was not detectable in type 1 (insulin-dependent) diabetic patients before and after glucagon administration. In type 2 (non-insulin-dependent) diabetic patients basal levels ranged from 2·2 to 14·5 pM and glucagon-stimulated levels ranged from 2·2 to 38·9 pM. The increase in IAPP varied from 0 to 24·4 pM.

The anti-human-IAPP serum had full cross-reactivity with rat IAPP (= mouse IAPP). Transgenic mice overexpressing the human IAPP gene showed elevated plasma IAPP levels as compared to (non-transgenic) control mice.

It is concluded that the method presented for the determination of IAPP in plasma is reliable and easy to perform, yielding reproducible results. The ability to measure plasma IAPP levels will help to elucidate the physiological function of IAPP as well as its pathophysiological role in type 2 diabetes mellitus.
Assay of the c-erbB-2 Oncogene Encoded Protein by ELISA and Immunocytochemistry in Human Breast Cancer
Authors: Nugent A , Gallagher J , Dolan J , O'Higgins N , Duffy M J
Published: February 2014

The c-erbB-2 gene is amplified in a wide variety of different adenocarcinomas. Generally, gene amplification correlates with increased expression of the c-erbB-2 oncoprotein. Previous assays for the c-erbB-2 oncoprotein have been qualitative or semi-quantitative. In this investigation using human breast cancers, c-erbB-2 oncoprotein levels as measured by enzyme-linked immunosorbent assay (ELISA) correlated significantly with semi-quantitation by immunocytochemistry ( r = 0·843, P<0·0001, n = 97). The cut-off point for the ELISA which gave the strongest agreement with immunocytochemistry was 15 units/μg protein. It is concluded that detection of c-erbB-2 oncoprotein by ELISA is quantitative and objective.
Inhibition of IMP Dehydrogenase by Mycophenolic Acid in Molt F4 Human Malignant Lymphoblasts
Authors: Stet Elisabet H , De Abreu Ronney A , Bökkerink Jos P M , Lambooy Lambert H J , Vogels-Mentink Trade M , Keizer-Garritsen Jenneke J , Trijbels Frans J M
Published: February 2014

The effects of inhibition of inosine monophosphate dehydrogenase (IMPDH), the rate-limiting enzyme in guanine nucleotide de novo synthesis, on cell growth, cell viability, endogenous nucleotide concentrations and concentrations of extracellular nucleosides and bases were studied in Molt F4 human malignant lymphoblasts. Mycophenolic acid (MPA) was used as a specific inhibitor of the enzyme activity. IMPDH activity was maximally inhibited with 0–5 μM MPA. After a 2 h exposure of the cells to 0–5 μM MPA, guanine nucleotides were depleted to approximately 50% of control values, whereas 5-phosphoribosyl-1-pyrophosphate levels increased to approximately 200%. Under these conditions, cytotoxicity became obvious after 24 h. Depletion of guanine nucleotides and cytotoxicity were prevented by addition of guanosine to MPA treatment. Daily supplements of guanosine were required to prevent MPA cytotoxicity during the entire incubation period of 72 h. We conclude that depletion of guanine nucleotides, induced by treatment with MPA, induces a severe and rapid cytotoxicity in Molt F4 cells.
On-Call Duties in Chemical Pathology: A Survey of Junior Medical Staff in the UK
Authors: Murphy M J , Paterson JR , Neithercut W D
Published: February 2014

To ascertain the extent of variation in out-of-hours duties among trainees in chemical pathology in the UK questionnaires were sent to 81 junior medical staff in 1992. Replies were received from 63 (78%). Although most had participated in an advisory rota, only 41 (65%) had participated in an analytical rota. Nine (14%) had participated in specialist analytical rotas, while 13 (21%) had experience of multidisciplinary rotas and only eight (13%) had experience of rotas involving clinical responsibility. Only 10 (16%) regularly reviewed their work on call with their senior medical staff. There was no single method of requesting tests out of hours in the trainees' laboratories and there was also considerable variation with respect to the tests available out of hours.

It is concluded that sufficient variation exists in the on-call experience gained by junior medical staff in chemical pathology to raise concern about the quality of training in out-of-hours work.
Lipid Levels in Schoolchildren in North East England: Effects of Feeding and Age
Authors: Azad K , Court S , Parkin J M , Laker M F , Alberti K G M M
Published: February 2014

Serum total cholesterol, high-density lipoprotein (HDL) cholesterol, triglyceride, apolipoprotein (apo) A-I and apoB concentrations were estimated and low-density lipoprotein (LDL) cholesterol levels were calculated in 132 children aged 11·4–17·3 years. The effect of feeding was investigated by estimating postprandial values and also by studying the effects of a test meal. The distribution of all data was consistent with Gaussian apart from triglycerides which was log normal. Overall fasting values were [mean (standard deviation; SD)] cholesterol 4·5 (0·8) mmol/L, HDL cholesterol 1·5 (0·4) mmol/L, LDL cholesterol 2·6 (0·8) mmol/L, apoA-I 1·5 (0·3) g/L, apoB 1·0 (0·4) g/L and triglycerides 0·76 (0·38–1·51) mmol/L, the values for triglycerides being mean (95% confidence intervals). Girls had higher triglycerides than boys [0·82 (0·43–1·54) versus 0·70 (0·36–1·33)] and different effects of age on lipids were found, HDL cholesterol being negatively correlated with age in boys ( r= −0·37; P<0·001), but not in girls, and apoA-I being negatively correlated with age in boys ( r= −0·31; P=0·006), but positively correlated with age in girls ( r = 0·32; P = 0·008). Triglycerides rose and HDL cholesterol fell following feeding and inconsistent effects were seen on apoA-I and apoB.
Relationships between Serum Saturated Fatty Acids and Serum Total Cholesterol and HDL-Cholesterol in Humans
Authors: Nagaya Teruo , Nakaya Ken-Ichi , Takahashi Akemi , Yoshida Izumi , Okamoto Yoshinari
Published: February 2014

To investigate the effects of serum saturated fatty acids (FAs) on human cholesterol metabolism, total-cholesterol (T-C), HDL-cholesterol (HDL-C), T-C/HDL-C ratio, and FA composition [myristic acid (MA, 14:0), palmitic acid (PA, 16:0) and stearic acid (SA, 18:0)] were determined in serum from 115 men and 120 women (20–70 years old). MA, PA and SA were expressed as percentages of serum total FAs. Using multivariate analysis to account for the confounding effects of age, body mass index, drinking, and smoking it was found that SA was negatively correlated with T-C and T-C/HDL-C ratio in both men and women. In men MA was negatively correlated with HDL-C, and in women SA was positively correlated with HDL-C. Although PA was the major component of serum saturated FAs, PA had no significant relation to any cholesterol indices in either sex. These results suggest that serum MA may aggravate and serum SA may improve cholesterol metabolism, thereby influencing the risk for ischaemic heart disease.
The Determination of IgG Subclass Concentrations in Serum by Enzyme-Linked Immunosorbent Assay: Establishment of Age-Related Reference Ranges for Cord Blood Samples, Children Aged 5–13 Years and Adults
Authors: Miles Judith , Riches Pamela
Published: February 2014

We describe a simple enzyme-linked immunosorbent assay for the measurement of immunoglobulin G (IgG) subclasses in serum. The microtitre plate is coated directly with diluted samples, standards or controls, blocked with phosphate-buffered saline containing 1% Tween to prevent non-specific protein binding to the plate, and each subclass assigned with specific mouse monoclonal antibody. The specific antibody is detected with alkaline-phosphatase linked anti-globulin and the colour development of the paranitrophenyl phosphate indicator reagent is measured at 405 nm until the highest concentration of standard gives an absorbance in excess of 1·4. Coefficients of variation measured at three concentration levels were less than 7% for within-assay variation and less than 10% for between-assay variation. Regression analysis of total IgG with the sum of the measured IgG subclasses gave a correlation coefficient of 0·932 ( P < 0·001). The assay has been used to establish age-related reference ranges for serum IgG subclasses; these are found to be slightly different from those established for radioimmunodiffusion methods. Our study does not confirm the previously reported absence of IgG4 in normal individuals.
Interference Due to Lipaemia in Routine Photometric Analysis—Survey of an Underrated Problem
Authors: Brady J , O'Leary N
Published: February 2014

Traditionally external quality assessment schemes (EQAS) distribute samples spectrally similar to a normal serum. This does not allow laboratories to assess the performance of their methods at measuring lipaemic samples. The Irish EQAS distributed a sample with a supplied lipid diluent. A sample of the same batch had previously been circulated as a normal distribution to obtain baseline values.

Most analytes were affected by the lipaemia. The degree of interference was instrument/method dependent and a wide range of values was reported for each analyte: total protein 51–134 g/L (baseline 65 g/L); albumin 33–56 g/L (baseline 42 g/L); calcium 2·12–6·10 mmol/L (baseline 2·34 mmol/L); urate 38–1100μmol/L (baseline 195μmol/L); creatinine 6–199μmol/L (baseline 140μmol/L); glucose 4·2–9·5 mmol/L (baseline 4·8 mmol/L); total bilirubin 1–192μmol/L (baseline 36μmol/L); urea 1·1–8·1 mmol/L (baseline 3·8 mmol/L); aspartate aminotransferase (AST) 12–105 iu/L (baseline 44 iu/L); iron 4·3–107μmol/L (baseline 26·8μmol/L); inorganic phosphorus 1·12–4·96 mmol/L (baseline 1·59 mmol/L); and cholesterol 2·5–17·1 mmol/L (baseline 4·1 mmol/L).

In situations where no clearing of the lipid occurs in the reagent, interference can be minimized by taking a sample blank reading or using a kinetic procedure. If clearing of the lipid does occur, time must be allowed for this to be completed before analytical readings are taken.
Laboratory Evaluation of the DCA 2000 Clinic HbA1c Immunoassay Analyser
Authors: John W G , Edwards R , Price C P
Published: February 2014

The DCA 2000™ clinical analyser for the measurement of haemoglobin A1c was evaluated for analytical quality. The analyser, which utilises inhibition of latex agglutination immunoassay, demonstrated good within-batch (1 · 9–3 · 1% CV) and between-batch (2·2% CV) imprecision, and was not affected by haemoglobin concentration. The analyser was linear throughout the analytical range, and was found to correlate well with agar electroendosmosis ( r = 0·93), affinity chromatography ( r=0·97), HPLC ( r=0 · 90) and EIA ( r=0·98). The analyser was found to give reliable analytical results, and with its ease of use, will provide the diabetologist with HbA1c results in the clinic; although an analysis time of 9 min will limit sample throughput.
Urine-Free Cortisol Excretion: Evidence of Sex-Dependence
Authors: Lamb Edmund J , Noonan Khatoon A , Burrin Jacky M
Published: February 2014

Measurement of urine-free (unconjugated) cortisol (UFC) excretion is widely used in the investigation of hypercortisolaemia. We have measured 24 h UFC excretion in normal healthy individuals using a radioimmunoassay (RIA) method claimed to be suitable for unextracted urine. Significantly higher rates of excretion were found in a group of 15 men compared with a group of 18 women, with median values of 230 (range 145–334) and 149 (range 67–315) nmol/24 h, respectively ( P<0·005). This method was used to reanalyse the urine samples after extraction with dichloromethane. Although values were significantly lower than those found with unextracted urine ( P<0·001), the male : female difference remained with median values of 140 (range 96–295) and 112 (range 29–196) nmol/24 h, respectively ( P<0·02). Rates of UFC excretion were measured on the same dichloromethane-extracted urine samples using a second, different RIA, which again demonstrated the male : female difference with median values of 151 (range 116–302) and 109 (range 36–205) nmol/24 h, respectively ( P<0·001). There was no significant difference between these values and those obtained with extracted urine in the first assay. The higher rates of UFC excretion in men compared to women does not appear to be due to the presence of interfering compounds since the difference is also present using extracted urine samples and with two methods using different antibodies. These results should be borne in mind by laboratories when interpreting UFC results.
A Characterization of the Blood Lead Concentrations in Saudi Arabian Children
Authors: Al-Saleh Iman A , De Vol Edward , Taylor Andrew
Published: February 2014

The results presented in this paper are those derived from an extensive analysis of lead in 1047 children aged 2 months to 16 years attending as outpatients at a reference hospital, taking cases from all parts of the Kingdom of Saudi Arabia. Since the distribution of blood lead data in the sample suggested the existence of two mixed sub groups among the studied children, a non-linear mathematical model was used fit to the data. More than 20% of the children had blood lead concentrations above 0·608μmol/L (12·59μg/dL).
Determination of Conjugated and Unconjugated Serum 3α-OH Bile Acids by High-Performance Liquid Chromatography
Authors: Goldsmith R F , Gruca M , O'Halloran M T , Earl J W , Gaskin K
Published: February 2014

A simple reverse-phase liquid chromatographic method has been developed for the quantitative measurement of 11 3α-OH bile acids in paediatric serum samples. Bile acids are enzymatically reduced to the corresponding 3-keto compound and then derivatized with the fluorophore dansyl hydrazine. Preliminary fractionation of bile acids is not required. The limit of detection is 0·1μmol/L using a sample size of 200μL. One hundred and twenty-three serum samples were analysed by the high-performance liquid chromatography (HPLC) method and the results compared with a commercial kit method (Enzabile) presently used in many laboratories for the measurement of total bile acids. There was a good correlation between the two methods ( r = 0·96). The method is suitable for use in a clinical laboratory for the further investigation of those patients with abnormally high total bile acid levels where quantification of bile acid fractions is required.
Determination of Glycated Apolipoprotein B in Serum by a Combination of Affinity Chromatography and Immunonephelometry
Authors: Panteghini M , Bonora R , Pagani F
Published: February 2014

We have developed and optimized a procedure for the quantitation of non-enzymatically glycated apolipoprotein B (apo B). Glycated and non-glycated apo B were separated from serum using m-aminophenylboronate affinity chromatography, determined by immunophelometry and the percentage of glycated apo B was calculated. The measuring range of the assay was 2·9–185 mg/dL apo B. The within- and between-run coefficients of variation were <7·4% and 14·6%, respectively, and recovery was >98%. Free glucose in serum did not affect the results at concentrations below 25 mmol/L. In 45 non-diabetic subjects the mean concentration of glycated apo B was 4.3% (SD 1%). In type 1 ( n = 17) and Type 2 ( n = 60) diabetic patients the mean glycated apo B concentrations were 5·3% (SD 0·7%) and 5·9% (SD 1·1%), respectively, significantly higher than in controls ( P<0·001).
Urinary N-Acetyl-β-Glucosaminidase Activity in Type I Diabetes Mellitus
Authors: Jones A P , Lock S , Griffiths K D
Published: February 2014

A commercial method for N-acetyl-β-glucosaminidase (NAG) is described for use on a discrete analyser. Timed overnight urine was obtained from 20 healthy volunteers and 60 Type I diabetic patients for estimation of NAG (expressed in relation to creatinine) and albumin excretion rate (AER). The upper reference limit for NAG excretion in the control patients was found to be 0·25 U/mmol creatinine but was abnormally raised in 60% of Type I diabetic patients before any increase in AER (greater than 20 μg/min), and in 82% of patients with AER greater than 200 μg/min. A positive correlation was found between NAG excretion and AER in Type I diabetes ( r = 0·61, p < 0·01), but not with glycaemic control as measured by serum fructosamine levels. We conclude that measurement of NAG excretion in diabetes indicates renal tubular dysfunction or damage before any significant change in albumin excretion rate.
Extraction and Purification of Gangliosides from Plasma and Fibroblasts before Analysis by Thin Layer Chromatography
Authors: Leenders R G G , de Jong J G N , Wevers R A
Published: February 2014

A procedure to extract and purify gangliosides from small volumes of plasma (0·6 mL), cerebrospinal fluid (1 mL) and fibroblasts is described. Gangliosides were extracted with chloroform/methanol and purified by means of reversed phase chromatography and gel filtration before analysis by thin layer chromatography. The procedure proved to be useful in confirming deficiency of lysosomal enzyme activity affecting ganglioside breakdown. The new procedure also appeared to be useful to monitor ganglioside catabolism in cultured fibroblasts loaded with ganglioside.
Rapid Diagnosis of Long Chain and Medium Chain Fatty Acid Oxidation Disorders Using Lymphocytes
Authors: Brivet Michèle , Slama Abdelhamid , Saudubray Jean-Marie , Legrand Alain , Lemonnier Alain
Published: February 2014

A method based on the release of tritiated water from [9,10(n)-3H] palmitic and myristic acids previously described for fibroblasts, was adapted for lymphocytes for the rapid diagnosis of fatty acid oxidation disorders. Optimal concentrations for both substrates and linearity of the assay were established. Normal values were established in control subjects of different age groups (58 children and 117 adults) and 16 patients with known fatty acid oxidation disorders were tested. Tritiated water production from patients' lymphocytes was expressed as a ratio between residual oxidations of palmitate and myristate and the results show that this method allows good differentiation between long chain and medium chain fatty acid oxidation defects.
A Rapid Method for Measurement of the Susceptibility to Oxidation of Low-Density Lipoprotein
Authors: McDowell Ian F W , McEneny Jane , Trimble Elisabeth R
Published: February 2014

Oxidation of low-density lipoprotein (LDL) may be important in the pathogenesis of atherosclerosis. We describe a method which measures the oxidation resistance of LDL isolated by a rapid procedure without added antioxidants. LDL was isolated from heparinized plasma by density gradient ultracentrifugation and desalted by gel filtration. The protein concentration was standardized to 50 mg/L and oxidation was promoted by copper (2 μmol/L) at 37°C. The total sample preparation time was 2·5 h. Conjugated diene production was monitored at λ = 234 nm with computation of the lag time. LDL oxidation was inhibited by EDTA but not heparin. Albumin inhibited LDL oxidation but only in concentrations greater than 50 mg/L. LDL was stable in frozen plasma (–70°C) for 10 weeks, but unstable in the isolated and desalted state. The lag time for LDL from patients treated with the antioxidant probucol was markedly prolonged compared to normal subjects.
Long-Term Physical Exercise and Lipoprotein(a) Levels in a Previously Sedentary Male and Female Population
Authors: Ponjee Gabriëlle A E , Janssen Eugene M E , van Wersch Jan W J
Published: February 2014

We investigated the effect of long-term physical exercise on serum lipoprotein(a) levels. 21 sedentary men and 15 sedentary women were trained three to four times a week with increasing intensity during 9 months. After 24 weeks all subjects ran a 15 km race and after 36 weeks a half marathon run (21 km). Blood samples were drawn before the training programme, 5 days before both races and 5 days after the half marathon run. Median (interquartile range) pre-training values in the male group were 32 (11–63) mg/L and in the female group 65 (23–199) mg/L. After 24 weeks of training, serum lipoprotein(a) concentrations had risen significantly in both male and female groups. Moreover, after 36 weeks of training, in preparation for the half marathon competition, median serum lipoprotein(a) rose almost twofold in both groups and was still elevated 5 days later. This study demonstrates that an exercise programme which includes running of increasing distances significantly increases serum lipoprotein(a) concentration.
Evaluation of a First-Line Spectrophotometric Screening Test for Increased Urine Porphyrin Excretion
Authors: Zuijderhoudt F M J , Bok J Dorresteijn-De , Te Velde K
Published: February 2014

We compared a spectrophotometric screening test for urine porphyrin concentration with a high performance liquid chromatography (HPLC) method. The screening test gave lower values than those obtained by HPLC, but the overall correlation was good. Occasionally, spectrophotometry failed to detect porphyrins in the urine which were detected by HPLC. The type of porphyria had no influence on the efficacy of the screening method. Receiver operating characteristic plot analysis of the screening test led to a cut-off value of 110 nmol/24 h with a sensitivity of 96% and a specificity of 86%. We conclude that the spectrophotometric screening method is useful for detection of increased total urine porphyrin concentration.
The Cryopreservation of Skin Biopsies—A Technique for Reducing Workload in a Cell Culture Laboratory
Authors: Gray R G F , Ryan D , Green A
Published: February 2014

A method is described for the cryopreservation of skin biopsies at −70°C for subsequent possible reculture. Biopsies stored up to 1 year could be successfully recultured without affecting the time to achieve confluence or the culture failure rate. This technique has been in operation in our department for over 3 years and has resulted in a demonstrable reduction in cell culture costs and a greater flexibility in the acceptance of skin biopsies for culture.
Serum Amyloid a Protein in Patients with Acute Myocardial Infarction
Authors: Časl Martin T , Šurina Branka , Glojnarić-Spasić Ines , Pape Ervin , Jagarinec Nada , Kranjčević Stjepan
Published: February 2014

The concentrations of four acute phase proteins were measured in sera of 40 patients with acute myocardial infarction (AMI) to evaluate their behaviour from day-to-day and to find out if they can serve for early prediction of postinfarction complications and mortality rate. Peak levels of serum amyloid A protein (SAA) were increased up to 5000-fold above the normal value and those of C-reactive protein (CRP) about 100-fold, 3 days after AMI. α 1-antichymotrypsin (ACT) and α 1-acid glycoprotein (AGP) peak levels were increased up to eightfold above their normal values. Patients who developed postinfarction complications had significantly higher SAA values on admission than those without complications (mean values of 379 and 45 mg/L, respectively; P < 0·0001). Using a level of 100 mg/L on admission as a reference value gave a reasonable sensitivity and predictive value for complications (73%) and a very good sensitivity (80%) for early prediction of fatal outcome. Patients with SAA values above this limit had double the risk of complications and four times the risk of a fatal outcome. The correlation with CRP values was lower than it was with SAA values ( P = 0·028) using a level of 15 mg/L on admission as reference value gave low sensitivity (55%) and predictive value (60%) for complications as well as low sensitivity for early prediction of fatal outcome (60%). The present study did not allow prediction of complications or mortality based on ACT or AGP values.
A Specific Radioimmunoassay for the Determination of Morphine-6-Glucuronide in Human Plasma
Authors: Chapman D J , Cross M J , Joel S P , Aherne G W
Published: February 2014

A specific antiserum for morphine-6-glucuronide (M6G) has been raised in a rabbit in response to immunization with a novel hapten: Protein conjugate (N-aminobutylnormorphine-6-glucuronide-thyroglobulin). Cross-reactivity with morphine and structurally related compounds was found to be negligible as expected from the nature of this immunogen. Using this antiserum, a simple, rapid and robust radioimmunoassay (RIA) has been developed for determination of M6G in samples of human plasma. The assay has a sensitivity of 0·05 ng/mL using 100 μL sample volumes and affords complete recovery of M6G over the range 2–200 ng/mL. The presence of morphine or morphine-3-glucuronide at concentrations up to 100 times the levels of M6G did not result in any measurable interference. Close agreement was obtained between M6G results obtained using the RIA and a specific high-performance liquid chromatography assay. This RIA offers an attractive alternative to existing methods for the determination of M6G in human plasma and will facilitate further metabolic and pharmacokinetic studies of morphine and M6G in the clinical setting.
Plasma and Urine Sialic Acid in Non-Insulin Dependent Diabetes Mellitus
Authors: Ozben Tomris , Nacitarhan Sabahat , Tuncer Nese
Published: February 2014

Urinary excretions of albumin, glycosaminoglycans (GAGS), total sialic acid (TSA), and lipid associated sialic acid (LASA) were measured in 78 non-insulin dependent diabetic patients (NIDDM) and 28 healthy subjects. TSA excretion was significantly higher in normoalbuminuric and microalbuminuric diabetic subjects than the control subjects and TSA excretion was correlated with urinary albumin excretion rate (AER). In normoalbuminuric diabetics, the duration of diabetes correlated significantly with both sialicaciduria and albuminuria. Although serum TSA levels were significantly higher in both diabetic groups than the control subjects, there was no correlation between serum and urinary TSA levels.
Determination of Free Triiodothyronine by Six Different Methods in Patients with Non-Thyroidal Illness and in Patients Treated with Amiodarone
Authors: Sapin Rémy , Schlienger Jean-Louis , Kaltenbach Georges , Gasser Françoise , Christofides Nicos , Roul Gérald , Gervais Anne , Petitjean Philippe , Chambron Jacques
Published: February 2014

We performed a methodological comparison of free triiodothyronine (FT3) estimates in patients with liver cirrhosis and renal failure. Patients were classified in terms of severity of illness on the basis of their total triiodothyronine, total thyroxine and reverse triiodothyronine profiles. FT3 levels, measured in direct dialysis, microchromatography, labelled analogue and two-step immunoextraction assays were significantly ( P < 0·01) lower than the control group in all patient categories. However, FT3 measured by a labelled antibody radioimmunoassay was significantly reduced only in the most severely ill sub-group of patients. In a further group of patients on long-term amiodarone therapy for cardiac disease all FT3 methods, with the exception of the labelled antibody radioimmunoassay and an analogue method, yielded significantly ( P < 0·01) reduced levels. A significant negative association between FT3 and subject age was demonstrated for all methods except the labelled antibody radioimmunoassay, and a weak but significant negative correlation between log thyrotropin and FT3 was only seen with this assay. Three methods demonstrated a correlation ( P < 0·02) with albumin levels in patients with the ‘low T3 syndrome’. In this group, albumin had a predictive value ( P ≤ 0·02) for four out of six assays as determined by stepwise variable selection. Our findings suggest that users of FT3 assays should exercise caution in interpreting results in non-thyroidal illness and amiodarone treated patients, as there are method-related differences in the profiles obtained.
Wide Diversity in Measurements of Growth Hormone after Stimulation Tests in Short Children are Due to Assay Variability
Authors: Barth J H , Smith J H , Clarkson P
Published: February 2014

A comparison of three commercially available assays for growth hormone (Pharmacia hGH RIA, IDS Gamma-BCT GH and Delfia 22 kDa hGH) were used to measure growth hormone (GH) secretion in 26 short children after pharmacological stimulation. The IDS Gamma-BCT assay was compared with Pharmacia assay in 15 provocative tests (13 children; n = 94). The Pharmacia assay showed a strong positive proportional bias and this was particularly marked at GH > 20 mU/L; the mean difference between the assays at GH < 10 mU/L was 12%. The IDS Gamma-BCT assay was also compared with the Delfia 22 kDa assay in 18 provocative tests (13 children; n = 100). Results from the IDS assay was higher throughout the range 0−90mU/L with a mean difference of 11·4% in the range 10−90 mU/L; the mean difference between the assays at GH< 10 mU/L was −39%.
Bone Alkaline Phosphatase in Rheumatic Diseases
Authors: Beyeler Christine , Banks Rosamonde E , Thompson Douglas , Forbes Mary A , Cooper Edward H , Bird Howard
Published: February 2014

A double monoclonal immunoradiometric assay specific for bone alkaline phosphatase (BAP) was used to determine whether the raised total alkaline phosphatase (TAP) often found in patients with active rheumatoid arthritis (RA) and ankylosing spondylitis (AS) is derived from bone or liver. Fifty-eight patients with RA were compared to 14 with AS and 14 with non-inflammatory rheumatic diseases (NI). None had clinical liver disease and only one had a slightly elevated aspartate transaminase activity. Elevated BAP concentrations were found in seven patients (5 RA, 1 AS, 1 NI), only two of whom also had abnormal TAP. Abnormal TAP activities were found in only three patients (all RA). BAP did not correlate with disease activity in RA or AS. In contrast, TAP correlated with disease activity (assessed by plasma viscosity) in RA ( P < 0·02) and AS ( P < 0·002) and γ-glutamyl transferase (GGT) also correlated with plasma viscosity in RA ( P < 0·01). Both TAP and BAP were significantly correlated with GGT in RA ( P < 0·001 and P < 0·02, respectively). These findings are discussed, together with possible reasons for the conflicting nature of some of the observations.