bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability of Parathyroid Hormone-Related Protein and Parathyroid Hormone at Room Temperature
Authors: Levin G E , Nisbet J A
Published: February 2014

The stability of plasma parathyroid hormone-related protein (PTHrP) as measured by the Nichols Institute assay at room temperature was assessed over a period of 72 h in blood samples collected in protease inhibitor tubes and EDTA tubes at 0, 6, 24, 48 and 72 h from 10 patients with hypercalcaemia of malignancy. Mean plasma PTHrP concentrations in blood samples collected in protease inhibitor tubes remained stable for up to 48 h but had decreased by 10% at 72 h. The mean EDTA plasma PTHrP at zero time was 67% of the protease inhibitor tube value and this had fallen to 39% at 72 h. The stability of parathyroid hormone (PTH) in separated blood samples was also assessed by collection into heparin and plain tubes as well as EDTA and protease inhibitor tubes. Serum PTH concentrations progressively declined throughout the 72 h study period although the zero time values were significantly higher than corresponding plasma PTH concentrations. Plasma PTH concentrations appeared to be stable when blood was collected in heparin, EDTA and protease inhibitor tubes during the 72 h period, except in one subject with markedly elevated plasma amylase activity.
Reflotron Cholesterol Measurement in General Practice: Accuracy and Detection of Errors
Authors: Ball M J , Robertson I K , Woods M
Published: February 2014

Comparison of cholesterol determinations by nurses using a Reflotron analyser in a general practice setting showed a good correlation with plasma cholesterol determinations by wet chemistry in a clinical biochemistry laboratory. A limited number of comparisons did, however, give a much lower result on the Reflotron. In an experimental situation, small sample volumes (which could result from poor technique) were shown to produce falsely low readings. A simple method which may immediately detect falsely low Reflotron readings is discussed.
Glycosyl Phosphatidyl Inositol Phospholipase D Activity in Human Serum
Authors: Maguire G A , Gossner A
Published: February 2014

We measured serum glycosyl phosphatidyl inositol phospholipase D (GPI-PLD) by its alkaline phosphatase releasing activity in healthy and diseased individuals. Linearity with respect to serum concentration was obtained only with very low serum volumes (below about 0·2 μL) necessitating a large predilution of serum to avoid potential artefacts. The assay was sufficiently precise for routine use. Patients with liver disease had lower activities and those with renal disease had higher activities than healthy controls. Following liver transplantation there was no correlation between GPI-PLD and conventional markers of liver function but there was a marked correlation with cholesterol concentration. These observations suggest that liver is a major source of GPI-PLD in serum. Its function remains unknown.
High-Performance Liquid Chromatographic Assay of Plasma Thalidomide: Stabilization of Specimens and Determination of a Tentative Therapeutic Range for Chronic Graft-Versus-Host Disease
Authors: Boughton B J , Sheehan T M T , Wood J , O'Brien D , Butler M , Simpson A , Hale K A
Published: February 2014

Thalidomide is now widely used to treat chronic graft-versus-host disease, but its use is associated with non-teratogenic side effects such as peripheral neuropathy. To examine the value of monitoring plasma concentrations of the drug in such patients, we have developed a high-performance liquid chromatographic (HPLC) assay. The method uses 0·5 mL plasma, is linear to 10 mg/L and had a detection limit of 0·2 mg/L. Thalidomide in plasma specimens was unstable at physiological pH but could be stabilized for several weeks by simple acidification. We describe a protocol for monitoring patients treated with thalidomide which permits convenient transportation and storage of specimens and report, provisionally, that plasma concentrations in the range 1–7 mg/L are therapeutically effective in chronic graft-versus-host disease without adverse side effects.
External Quality Assessment of Urinary-Free Cortisol Measurement in the UK against a Gas Chromatography Mass Spectroscopy Reference Method
Authors: Holder Geoffrey
Published: February 2014

The performance of methods used for the measurement of urinary-free cortisol (UFC) has been monitored in the UK by an external quality assessment scheme (EQAS). Bias and variation of the bias (VAR) from the all laboratories trimmed mean (ALTM) show that mean bias ranged from −15·5% to + 83·1% and mean VAR from 9·3% to 53·2%. The dominant kit methods had a bias range of −4·2% and + 56·9% and VAR between 11·4% and 18·4%. Recovery of added cortisol ranged from 74·9% to 207·2%. The precision of the estimate of urinary-free cortisol was different for different methods and changed with concentration.

When methods were compared with a gas chromatography mass spectroscopy (GCMS) target there was a linear correlation between per cent bias from the ALTM and from the GCMS result with the ALTM averaging 63·1% greater than the GCMS value.
An Improved Method for the Quantitation of Apolipoprotein B and Apolipoprotein A-1 in Dried Blood Spots
Authors: Wong N , Beeso J , Sherwood R A , Peters T J
Published: February 2014

An extraction protocol has been developed to elute apolipoprotein B (apo B) and apolipoprotein A-1 (apo A-1) from dried blood spots with assay of the extracted apolipoproteins by automated immunoturbidimetry. Various extraction media were investigated to assess their elution efficiency and the optimum medium was found to be deionized water. Studies on the rate of elution suggested both apolipoproteins were eluted readily in less than an hour with a recovery of 71% for apo B and 65% for apo A-1. Extracted apo B but not apo A-1 was found to be stable for 24 h when kept at 4°C. The within-batch coefficients of variation (CV) for the combined extraction and assay of apo B were found to be 5·9% and 8·5% at 0·6 g/L and 1·2 g/L respectively. The CVs for apo A-1 were found to be 7·4% at 0·7 g/L and 8·9% at 1·5 g/L. Antiserum from three sources (Immuno, Incstar and Bayer) was investigated for immunoreactivity with apo B and apo A-1 and cross-reactivity with red blood cells was also assessed. Although the antisera from the three companies showed similar immunoreactivity towards apo B and apo A-1, antiserum from Bayer was found to cross-react with red cells.
Measurement of Markers of Tobacco Smoking in Patients with Coronary Heart Disease
Authors: Archbold G P R , Cupples Margaret E , McKnight Agnes , Linton T
Published: February 2014

591 patients with a history of coronary heart disease had one or more biochemical markers of tobacco smoking measured. 26% were self reported smokers and a further 4% were apparent ‘smoking deceivers’. The urinary nicotine metabolite concentration is an excellent marker for tobacco smoking; breath CO would be a suitable alternative for busy clinics. Half the patients were subjected to regular advice on risk factor management but there was no evidence that this contributed effectively to smoking cessation. Overall smoking cessation rate was poor.
Lower Values for Immunoglobulin M in Cerebrospinal Fluid When Sampled with an Atraumatic Sprotte Needle Compared with Conventional Lumbar Puncture
Authors: Öhman Sten , Ernerudh Jan , Forsberg Pia , Roberg Magnus , Vrethem Magnus
Published: February 2014

Immunoglobulin M (IgM) has a very low concentration in cerebrospinal fluid (CSF) compared with serum, and therefore determinations of IgM in CSF are highly sensitive to pre-analytical errors caused by contamination with serum or interstitial fluid. Capillary attraction causes a thin layer of liquid containing serum proteins to be formed inside a conventional (Quincke) needle during penetration of tissue. To investigate this source of pre-analytical error, 35 patients had lumbar punctures using a 22 G atraumatic (Sprotte) or 25 G conventional (Quincke) needle according to a randomized scheme, and the IgM concentrations in CSF and serum were determined.

The CSF IgM concentrations for samples taken with a Sprotte needle were significantly lower than those taken with a Quincke needle ( P < 0·05), whereas the corresponding serum IgM concentrations and CSF erythrocyte counts did not differ significantly. The difference indicates that CSF IgM concentrations determined after conventional sampling may be falsely increased by contamination. We conclude that IgM concentrations in CSF samples taken with the atraumatic technique are more accurate, and recommend the use of this technique when CSF IgM is to be determined.
Thyroid Stimulating Hormone Measurement Using a Third Generation Immunometric Assay
Authors: Squire Christine R , Fraser William D
Published: February 2014

After an initial evaluation of the standard procedure for performance of a third generation TSH (thyroid stimulating hormone) assay (Amerlite TSH-30) modifications were made to standardize the timing of measurement of light emission following signal reagent addition. By adopting this optimized procedure, a significant improvement in assay sensitivity was achieved when compared to a second generation TSH assay (DAKO). Using the optimized assay the sensitivity was 0·003 mU/L (20 replicates of zero) or 0·009 mU/L [22% CV (coefficient of variation) from the precision profile]. Recovery of added TSH and parallelism of the assay were good. A significant negative bias was detected for the Amerlite TSH-30 assay when compared to the DAKO assay (log y = 0·92 log x − 0·33, n = 210). Excellent discrimination was achieved between euthyroid, hypothyroid and thyrotoxic subjects. A high percentage of thyrotoxic patients had undetectable TSH and the spread of values between thyrotoxic and euthyroid was greater with the third generation assay. In patients receiving thyroxine therapy a higher percentage had detectable TSH values. The optimized Amerlite TSH 30 assay offers improved assay performance when compared to a second generation assay.
Measured versus Calculated Latent Iron Binding Capacity in Plasma of Newborns
Authors: Lentjes Eef G W M , Lindeman Jan H N , van de Bent Wil , Berger Howard M
Published: February 2014

Iron overload as well as iron deficiency may play a role in the pathogenesis of diseases in the newborn and infant and therefore knowledge of the iron status is essential. Using an automated method for the determination of plasma latent iron-binding capacity (LIBC) we measured the LIBC in 20 full term and 20 preterm babies and 20 adults. LIBC was also calculated from transferrin and iron concentration.

The measured LIBC strongly deviated from calculated LIBC in some samples and in seven of 20 preterm babies no LIBC could be detected, suggesting the presence of non-protein-bound iron fraction. The results suggest that in the neonate calculated LIBC overestimate the ability of the plasma to bind excessive iron.
Quantification of Serum Proteins Using Capillary Electrophoresis
Authors: Jenkins M A , Guerin M D
Published: February 2014

Capillary electrophoresis is a technique that can be automated for the separation of charged particles. By investigating suitable sample dilution and injection time and adhering to a strict washing procedure we have been able to quantify paraproteins in serum samples. This has enabled us to use the technique of capillary electrophoresis for the provision of serum protein electrophoresis in a routine clinical laboratory.

We present our findings of 260 serum samples, which included 76 samples with paraproteins analysed by both capillary electrophoresis (EC) and high resolution agarose gel electrophoresis (HRAGE). CE was able to detect all the monoclonal bands detected by HRAGE, and, in particular, better able to detect IgA monoclonal bands occurring in the beta region. The major advantages of CE over HRAGE relate to the automated nature of CE with the elimination of the need for a densitometer.
Paraprotein Interference Causing Pseudohyperphosphataemia: Evaluation of an Improved Methodology
Authors: Savory D J , Pearce C J
Published: February 2014

The measurement of serum inorganic phosphorus by direct acid/molybdate assay is known to be subject to interference by some serum paraproteins. Serum samples from 45 paraproteinaemic patients were used for the measurement of inorganic phosphorus using a manufacturer's kit reagent and a detergent-modified reagent from the same manufacturer. In addition, the same samples were analysed with both reagents following precipitation of serum protein with trichloroacetic acid. Using the original reagent pseudohyperphosphataemia was found in 27% (12/45) of the samples. The modified reagent was free from interference with no significant difference between results from serum and protein-free supernatants.
Analysis of Sweat Chloride by Reversed Phase High-Performance Liquid Chromatography
Authors: Keevil B G , Wong W K
Published: February 2014

A high-performance liquid chromatography (HPLC) method for the determination of sweat chloride was developed and evaluated. This method is capable of measuring chloride ion in sweat eluates with an analytical working range from 0·5 mmol/L to 6 mmol/L (15 to 180 mmol/L in undiluted sweat samples). Precision studies showed that at the levels of 1 mmol/L, 2·5 mmol/L and 3·5 mmol/L, the within batch coefficients of variation were 1·26%, 0·88% and 0·43%, respectively, and the between batch coefficients of variation were 1·31%, 1·75% and 1·07%, respectively. The minimum detection limit was 0·5 mmol/L. This method correlated well with the ion-selective electrode (ISE) method currently in use.
Assessment of Iron Status in Association with Excess Alcohol Consumption
Authors: Ford C , Wells F E , Rogers J N
Published: February 2014

Biochemical evidence of iron overload (transferrin saturation greater than 60% and/or serum ferritin concentration greater than 1000 μg/L) was observed in 16% of patients admitted to an alcohol withdrawal unit. No subjects in an age and sex matched control group showed such biochemical changes.

Whilst changes in serum ferritin concentration closely correlated with aspartate aminotransferase activity and could be explained by alcohol induced liver damage, the increased transferrin saturation was not similarly explained.

In nine patients withdrawal of alcohol resulted in a decrease in transferrin saturation and serum ferritin, the former due to a reduction in serum iron concentration. In patients with high alcohol intake biochemical measures of iron status may be misleading and a decrease in both transferrin saturation and serum ferritin concentration after withdrawal of alcohol may help to rule out the possible diagnosis of hereditary haemochromatosis.
Rapid Determination of Amphetamine Stereoisomer Ratios in Urine by Gas Chromatography—Mass Spectroscopy
Authors: Tetlow V A , Merrill J
Published: February 2014

We describe a method for the determination of amphetamine optical isomer ratios. A simple basic extraction of amphetamine from urine is followed by on-column derivatization with (S)–(−)-N-(trifluoroacetyl)-L-prolyl chloride and analysis by gas chromatography—mass spectroscopy. This approach has been shown to be satisfactory for the separation of d- and l-amphetamine isomers and precision data shows the method to be reproducible. Patient data is presented to demonstrate the ability to differentiate between patients taking d-amphetamine and those using illicit (racemic) amphetamine by their l/d amphetamine ratio.
Indirect Sandwich Enzyme-Linked Immunosorbent Assay (ELISA) for Plasma Apolipoprotein E
Authors: Kee Patrick , Bais Renze , Sobecki Stan K , Branford Susan , Rye Kerry-Anne , Barter Philip J
Published: February 2014

We have developed an indirect sandwich ELISA for measuring plasma apolipoprotein E (apo-E), using commercially available antibodies. A monoclonal anti-apo-E was used as the capture antibody and the captured apo-E detected with polyclonal anti-apo-E antiserum (goat). The detecting antibody was quantitated using horseradish peroxidase-conjugated rabbit immunoglobulin to goat immunoglobulins. There was no detectable cross-reactivity between the three antisera. Interference with the assay by apolipoprotein A-1, bilirubin and haemoglobin was not significant up to 1·7 g/L, 1250 μmol/L and 13·0 g/dL, respectively. The ELISA method showed high correlation with an established immunonephelometric method (ELISA apo-E=104 Immunonephelometric apo-E+16; r2 = 0·954, P < 0·0001, n = 39). The assay has a measuring range between 5 and 560 mg/L. The coefficient of duplicates was 20%, within-run coefficients of variation (CV) ranged from 3·7 to 6·0% and between-run CV from 6·1 to 15·1%. The reference range determined for 168 normotriglyceridaemic subjects was 20 to 130 mg/L. In an analysis of the lipoprotein subfractions isolated by ultracentrifugation as the fraction of density less than 1·25 g/mL and separated by gel permeation chromatography, apo-E was found to be associated with very low-density lipoprotein and large high-density lipoprotein.
Cushing's Syndrome and Hypothalamic-Pituitary Adrenal Axis Suppression Induced by Medroxyprogesterone Acetate
Authors: Malik K J , Wakelin K , Dean S , Cove D H , Wood P J
Published: February 2014

The referral of a patient with features of Cushing's syndrome but with suppressed plasma cortisol and adrenocorticotrophic hormone concentrations prompted us to study the effect of medroxyprogesterone acetate (MPA) therapy on the adrenal axis. 11 women (aged 54–82 years) who were receiving 200–400 mg/day MPA were studied. Of these, four had subnormal plasma cortisol responses to a short synacthen test, and two more had borderline responses (30 min post-synacthen plasma cortisol results of 411 and 511 nmol/L). We conclude that suppression of the adrenal axis occurs relatively frequently in patients on MPA and that such patients should be checked for evidence of suppression before MPA therapy is withdrawn.
Comparison between Equimolar- and Skewed-Response Assays of Prostate Specific Antigen: Is There an Influence on the Clinical Significance When Measuring Total Serum Prostate Specific Antigen?
Authors: Jung Klaus , Lein Michael , Schnorr Dietmar , Brux Brigitte , Henke Wolfgang , Loening Stefan
Published: February 2014

Using the Tandem®-E, Axsym® and LIA-mat® assays, prostate specific antigen (PSA) was measured in pure PSA solutions of known concentrations of free and complexed PSA and in serum of patients with prostate cancer ( n = 31), benign prostate hyperplasia ( n = 32) and in healthy controls ( n = 27). Measurements of pure PSA solutions showed that the AxSym® assay exemplified typical properties of the skewed-response assay reacting more to free PSA than to the complexed PSA forms whereas the other two assays showed an equimolar-response. When PSA was measured in the serum of the three groups, the AxSym® test and Tandem®-E gave similar PSA values whereas the LIA-mat test yielded significantly lower values. These results were not related to the amount of free PSA in the samples and proved that discordant PSA values between PSA assays were not mainly caused by the use of skewed- or equimolar assays. Despite these differences, receiver-operation characteristic analysis confirmed that the clinical validity of all three PSA tests did not differ.
A Rapid Anion Exchange High-Performance Liquid Chromatography Method for the Measurement of HbA2 in Whole Blood
Authors: Keevil B G , Maylor P W , Rowlands D
Published: February 2014

We developed a binary gradient high-performance liquid chromatography (HPLC) method for measuring HbA2 in whole blood samples using a Pharmacia Mono Q column (1 mL) and measurement at 415 nm. The assay requires a simple lysis and centrifugation step before injection onto the column. We found good agreement of results between the HPLC method and the Helena column chromatography method. The within batch precision was 2·6% and between batch precision was 4·6%. We found that using 30 mM Tris buffers (pH 7·8) with a sodium chloride gradient resulted in short analysis times and good chromatographic separation of HbA2, HbS and HbA. We conclude that this is a robust assay for the diagnosis of β-thalassaemia.
Comparison of Biochemical Markers of Bone Resorption in Patients with Metabolic and Malignant Bone Diseases
Authors: Withold W , Friedrich W , Reinauer H
Published: February 2014

The clinical usefulness of the urinary excretion of three bone resorption markers is compared in patients after renal transplantation and in tumour patients with and without bone metastases. The markers were the 3-hydroxypyridinium derivatives pyridinoline and deoxypyridinoline (pyridinium cross-links; measured by a polyclonal enzyme immunoassay), the cross-linked N-telopeptid-to-helix domain of type I collagen and the destruction products of type I collagen metabolism cross-reacting with a peptide sequence of the α1-chain of the C-terminal telopeptide region of type I collagen (CrossLaps™).

In patients receiving renal transplantation the discriminating power of N-telopeptides was superior to that of pyridinium cross-links and CrossLaps™, with Z scores (number of SDs from apparently healthy controls) of 6·61, 2·17 and 1·35, respectively. However, the pyridinium cross-links were the only markers for bone resorption which showed a significant increase with time ( P < 0·001).

Receiver operating-characteristic analysis for discriminating patients with bone metastases from those without revealed that the accuracy was 0·81 for pyridinium cross-links, 0·76 for the N-telopeptides and 0·61 for CrossLaps™. The discriminating power for patients with bone metastases was higher for pyridinium cross-links and N-telopeptides than for CrossLaps™, with Z scores (number of SDs from patients without bone metastases) of 4·38, 3·00 and 1·24, respectively. Linear correlation coefficients for the different markers were between + 0·35 and + 0·65 in patients receiving renal transplants, and between + 0·58 and + 0·84 in patients with bone metastases.

In conclusion, in patients with metabolic and malignant bone diseases there are marked differences in the diagnostic performance of different biochemical markers of bone resorption. It is suggested that this may reflect the different facets of bone resorption or the different metabolic fates of the marker substances examined.
Salivary Creatinine Assays as a Potential Screen for Renal Disease
Authors: Lloyd Jonathon E , Broughton Arthur , Selby Colin
Published: February 2014

Salivary creatinine concentrations are 10–15% of serum creatinine concentrations in healthy populations but have not previously been measured in patients with renal disease. The Cobas Mira automated Jaffe method was adapted to measure salivary creatinine concentration. The method was linear to 1200 μmol/L, had a mean recovery of 78% and a detection limit of 6 μmol/L. Intra-assay variability was 13·5, 5·5 and 1·4% at 10·6, 17·8 and 128·4 μmol/L, respectively. Inter-assay variability was 35·0 and 4·8% at 6·2 and 130·4 μmol/L, respectively. The median salivary creatinine concentrations was 8·5 μmol/L (range 6–18 μmol/L) in healthy subjects ( n = 23), and 84 μmol/L (range 18–591 μmol/L) in patients with renal disease ( n = 25). Salivary and serum creatinine concentrations were not related in healthy subjects, however, a significant relationship was found in the patients ( r = 0·784, P < 0·001). Using salivary creatinine concentration of 16·8 μmol/L as a cut off value, all patients would have been detected with one false positive result (sensitivity 100%, specificity 95·7%, efficiency 97·7%). Thus, salivary creatinine estimations may be used to identify subjects with serum creatinine concentrations above 120 μmol/L.
Lipoprotein(a) in Korean Children and a History of Coronary or Cerebral Vascular Events in Their Older Family Members
Authors: Choe Yon H , Choi Yong , Kim Jin Q
Published: February 2014

The purpose of this study was to determine the relationships between serum apolipoprotein concentration and family history of coronary or cerebral events in schoolchildren. In 269 primary schoolchildren aged 6–11 years (145 boys and 124 girls) we measured the blood concentrations of total cholesterol, apolipoproteins B and A-1, and lipoprotein(a), and questioned their parents about coronary or cerebral vascular events. Serum concentrations of apo B, A-1 and Lp(a) significantly increased with age. In children with serum cholesterol concentration > 5·18 mmol/L the concentrations of apo B, A-1, Lp(a) and apo B/apo A-1 ratio were significantly higher. The concentrations of total cholesterol, apo B, Lp(a), and apo B/apo A-1 ratio in the obese group (body weight 20% above the median body weight for age and height) differed significantly from those in the non-obese group. Serum concentrations of Lp(a) in the children who had positive family histories of coronary or cerebral events (geometric mean = 0·174 × / ÷ 0·036g/L) and was significantly higher than that in the children with negative history (geometric mean = 0·086 × / ÷ 0·36g/L). Family history was an independent and major contributor to high Lp(a). In evaluating children's lipid profiles, measurement of Lp(a) may help to identify children and their families at increased risk and this may facilitate the targeting of preventive measures.
Cardiac Troponin I Should Replace CKMB for the Diagnosis of Acute Myocardial Infarction
Authors: Bhagat Chotoo I , Langton Paul , Lewer Michelle , Ching Simon , Beilby John P
Published: February 2014

Cardiac troponin I (cTnI) has been reported to be a highly specific marker for cardiac injury. We investigated the performance of this assay in patients admitted to a coronary care unit for suspected acute myocardial infarction (AMI), patients with extensive skeletal muscle damage, marathon runners and as a routine diagnostic test over a four week period. cTnI proved to be as sensitive a marker for AMI as creatine kinase/MB isoenzyme (CKMB) in patients admitted to the coronary care unit. In 10 patients with a proven AMI, the cTnI remained elevated from 69 to 183 h with a median time of 127 h. Cardiac troponin I had superior specificity to CKMB in patients with skeletal muscle damage. It was very useful in these patients to confirm or exclude concurrent myocardial damage. In routine diagnostic use, cTnI had greater efficiency than CKMB to classify patients as having an AMI. Consequently cTnI should replace CKMB as a marker for AMI.
Vanadium-Mediated Oxidation of NADH is Enhanced by Aluminium and Inhibited by Vitamin E and Some Copper (II) Complexes
Authors: Abou-Seif Mosaad A M
Published: February 2014

The effect of aluminium on vanadium-mediated oxidation of NADH was examined. The oxidation of NADH was enhanced in the presence of aluminium. The effect was concentration dependent. Vitamin E and copper (II) complexes with superoxide dismutase (SOD)-like activities containing isobutyric acid hydrazine were tested for their effect on the vanadium-mediated oxidation of NADH. The stimulatory effect of aluminium was decreased upon addition of different concentrations of vitamin E and copper (II) complexes. These results indicate that the biological toxicity of aluminium may be attributed to its enhancement of the production of superoxide radicals (O2−) in association with the accumulation of other trace elements such as vanadium.
Urinary Excretion of Albumin and Retinol Binding Protein in Systemic Lupus Erythematosus
Authors: Guy J M , Brammah T B , Holt L , Bernstein R M , McMurray J R , Tieszen K , Cooper R G
Published: February 2014

We have measured the urinary excretion of total protein, albumin and retinol binding protein (RBP) in random urine specimens obtained from 40 female patients with systemic lupus erythematosus (SLE). Thirty-three of these patients had no clinical evidence of any renal impairment (non-renal SLE); seven had overt renal disease (renal SLE). RBP: creatinine ratios were significantly higher in non-renal SLE patients compared with female controls ( P = 0·002). There was no significant difference between urine total protein concentrations, albumin: creatinine or total protein: creatinine ratios in non-renal SLE patients when compared with controls, despite approximately 20% of these patients having elevated excretion of total protein or albumin. All seven renal SLE patients had elevated albumin: creatinine ratios but only four of them had an increased RBP: creatinine ratio. Of 29 non-renal SLE patients who had urinary total protein concentrations below 0·2 g/L, (i.e. approximating to a negative protein dipstick), 14 had increases in either albumin : or RPB: creatinine ratios. Only two patients had increases in both. In the absence of clinical evidence of renal disease, increases in urinary albumin or RBP excretion could indicate subclinical nephropathy and measurements may have a role in the early diagnosis and subsequent monitoring of renal disease in SLE.
A Simple Bacterial Bioassay for the Measurement of L-Glutamine
Authors: Keast D , Harper W , Rowbottom D G , Greig J E , Kargotich S , McBride S
Published: February 2014

The amino acid L-glutamine has been shown to be important to numerous cells in the body. However, the routine measurement of glutamine in biological solutions is complicated by its relative instability, particularly at extremes of pH. We report a simple bacterial bioassay method for the estimation of glutamine, carried out at neutral pH, using an Escherichia coli that is specifically dependent on the presence of glutamine for replication. The assay is simple to perform and we have shown it to be highly reproducible. Furthermore, we observed significant correlation between the estimations of glutamine by the bioassay system and current methodologies. The levels of glutamine recorded were higher than by other methods. We also found that deproteinization and neutralization of samples allowed them to be stored at − 70°C for up to 24 weeks without deterioration.
Interference Due to Haemolysis in Routine Photometric Analysis—A Survey
Authors: Brady John , O'Leary Niall
Published: February 2014

To assess the affect of haemolysis on routine photometric methods used by participants in the Irish External Quality Assessment Scheme for Clinical Biochemistry (1EQAS) a sample was distributed with a supplied diluent containing haemoglobin. A sample of the same batch had previously been circulated as a normal distribution. Many analytes/methods were affected by the haemolysis. The range of values reported for each analyte was as follows. Albumin 34–48 g/L (baseline 37 g/L). Calcium 2.16–2.68 mmol/L (baseline 2.34 mmol/L). Urate 90–470 μmol/L (baseline 195 μmol/L). Creatinine 55–161 μmol/L (baseline 140 μmol/L). Glucose 4.1–5.6 mmol/L (baseline 4.8 mmol/L). Bilirubin 14–60 μmol/L (baseline 36 μmol/L). Urea 3.4–7.3 mmol/L (baseline 3.8 mmol/L). Iron 17.9–55.0 μmol/L (baseline 26.8 μmol/L). Inorganic phosphorus 0.22–2.41 mmol/L (baseline 1.59 mmol/L). Cholesterol 3.0–5.9 mmol/L (baseline 4.1 mmol/L). In some situations the use of an appropriate blank may solve the problem, but it must be remembered that interference caused by haemoglobin may be more complex than merely spectral.
Simplified Detection of a Mutation Causing Familial Hypercholesterolaemia Throughout Britain: Evidence for an Origin in a Common Distant Ancestor
Authors: Wenham Philip R , Haddad Lema , Panarelli Maurizio , Ashby J Peter , Day Ian N M , Giles Paul D , Humphries Steve E , Penney Michael D , Rae Peter W H , Walker Simon W
Published: February 2014

Familial hypercholesterolaemia (FH) is an inherited autosomal codominant disorder caused by many different mutations in the low-density lipoprotein receptor (LDLR) gene. The one described most frequently in patients with FH from England, arises from a G→A transition at the first nucleotide of codon 80, resulting in the substitution of lysine for glutamic acid at residue 80 of the mature protein, FH E80K.

We describe a simple method to detect this mutation in genomic DNA using the polymerase chain reaction (PCR). A 69 base pair (bp) fragment of exon 3 of the LDLR gene is amplified using a mutagenic upstream PCR primer. This substitutes a T for an A residue in the amplified product, 2 bp upstream from the mutant site, generating a restriction site for the endonuclease Taq I, in normal, but not in mutant DNA. Following digestion of amplified DNA with Taq I, normal but not mutant DNA is cut into two fragments of 29 and 40 bp, which are readily identified by polyacrylamide gel electrophoresis.

Using this method, 410 patients with clinically diagnosed FH, attending lipid clinics in Edinburgh (72), Newport (158), Walsall (30) and Southampton (150), were screened for the mutation. Five individuals tested positive as heterozygotes, one from Edinburgh, three from Newport and one from Southampton. This finding was confirmed by DNA sequence analysis. We conclude that FH due to this mutation occurs in individuals throughout Great Britain and that it can be detected acccurately using this simple technique.

DNA from these and other individuals previously identified to be heterozygous for FH E80K, was then studied using PCR of highly informative microsatellite markers flanking the LDLR gene. Sixteen of 17 apparently unrelated individuals heterozygous for FH E80K also were heterozygous for an identical size (239 nucleotide) allele, of polymorphic microsatellite D19S394, located approximately 250 kb away from the LDLR gene. This supports the hypothesis that FH E80K in these 16 individuals arose from a single ancestor less than 1000 years ago.
Butyrylcholinesterase Genes in Individuals with Abnormal Inhibition Numbers and with Trace Activity: One Common Mutation and Two Novel Silent Genes
Authors: Dey Dilip Chandra , Maekawa Masato , Sudo Kayoko , Kanno Takashi
Published: February 2014

A random population was screened for abnormal dibucaine and fluoride numbers (DN & FN) to find some common mutations in butyrylcholinesterase ( BCHE) gene. Of 2375 unrelated individuals, 10 were found to have low DN and FN and were selected for further studies. DNA analysis of these hypocholinesterasemics revealed that seven patients were heterozygous for missense mutation at codon 330 (TTA to ATA; BCHE*330I). The frequency of BCHE*330I mutation was calculated to be at least 0.29% among the Japanese. On the other hand, two novel mutations were found in three families and two individuals including probands whose enzyme activity was very low (silent gene). Polymerase chain reaction and single stranded conformation polymorphism (PCR-SSCP) and restriction fragment length polymorphism (PCR-RFLP) were used for identification of the common and known mutation types such as BCHE*250P (ACT to CCT), BCHE*365R (GGA to CGA), and BCHE*539T (GCA to ACA; K-polymorphism), whereas PCR-SSCP was used in combination with direct DNA sequencing for new mutations like BCHE*446V (TTT to GTT) and BCHE*451X (GAA to TAA).
Biochemical Markers of Acute Myocardial Infarction: Strategies for Improving Their Clinical Usefulness
Authors: Katz Ian A , Irwig Les , Vinen John D , March Lyn , Wyndham Lindsay E , Luu Tuan , Nelson Greg I C
Published: February 2014

We investigated the early diagnostic utility, including incremental value, of the serum cardiac markers creatine kinase (CK), CK-MB (mass and activity measurements), cardiac troponin T, and myoglobin in the diagnosis of acute myocardial infarction (AMI) in patients presenting to a major teaching hospital with chest pain and non-diagnostic electrocardiographs (ECG). The reference diagnosis of acute myocardial infarction was made by a single, independent cardiologist using World Health Organization criteria. CK and CK-MB mass were the only significant predictors of AMI at presentation to the Emergency Department. Logistic regression analysis revealed that CK did not significantly predict ( P = 0·23) myocardial infarction once CK-MB mass was in the model. Using test results on follow up, in addition to presentation CK-MB mass, change in CK-MB mass was the only other significant independent predictor of AMI. Likelihood ratios for various levels of the significant markers in the logistic regression are given. In conclusion, CK-MB mass measurement was the only useful serum cardiac marker for the diagnosis of AMI in patients presenting with chest pain with non-diagnostic ECGs.
Dissociation of Bone Turnover in Anorexia Nervosa
Authors: Stefanis Nicholas , Mackintosh Christine , Abraha Hagosa D , Treasure Janet , Moniz Caje
Published: February 2014

Biochemical markers were measured to assess bone turnover in a cross-sectional study of 43 patients with anorexia nervosa; 28 were at their first assessment (untreated) with a body mass index (BMI) (median interquartile range) of 13·3 (2) kg/m2. A second group of 15 patients undergoing treatment (treated) had a median BMI of 17·6 (2·8) kg/m2. The median, interquartile range of urinary deoxypyridinoline (DPyd), a bone resorption marker, was raised in both groups compared with an age-matched control population [DPyd = 17·8 (15·2), 17·5 (16·4) and 9·2 (4·0) nmol/mmol creatinine, respectively]. Serum type 1 collagen carboxyterminal propeptide (P1CP), a marker of bone formation, was similar to controls in the untreated patients [112 (29) and 112 (78·5)ng/ml, respectively], but was significantly raised in the treated patients [163 (219)ng/ml, P < 0·05]. A second group of 21 patients was followed prospectively, on admission and during 8 weeks of intensive inpatient care (BMI on admission and after 8 weeks was 13·0 (2) and 16·7 (3) kg/m2, respectively). The resorption marker, serum type 1 collagen carboxyterminal telopeptide (1CTP) was raised on admission and remained high during treatment. P1CP and osteocalcin levels were similar to control levels on admission but increased with treatment, and after 8 weeks were 40% and 63% higher respectively than on admission. These findings suggest that in untreated anorexia nervosa there was uncoupling of bone turnover as bone resorption markers were raised without a concomitant increase in bone formation markers. As the condition was treated and patients gained weight, the formation markers also increased, leading to a more balanced, although higher, bone turnover.
Amperometric Determination of High-Density Lipoprotein Cholesterol Using Polyethylene Glycol-Modified Enzymes and a Peroxidase-Entrapped Electrode
Authors: Kinoshita Hideaki , Torimura Masaki , Kano Kenji , Ikeda Tokuji
Published: February 2014

A peroxidase-entrapped and ferrocene-embedded carbon paste (POD-Fc-CP) electrode allows a highly sensitive detection of H2O2 at levels as low as 10 nmol/L with practically no interference by coexisting substances, turbidity or coloration of samples. The electrode was applied to the amperometric determination of high-density lipoprotein (HDL)-cholesterol in a very small volume (1–2 μL) using polyethylene glycol (PEG)-modified cholesterol esterase and cholesterol oxidase without prior precipitation or separation of HDL. PEG-modified enzymes exhibit a selective activity toward HDL-cholesterol in the presence of dextran sulphate and MgCl2 to generate H2O2. The HDL-cholesterol concentrations of human serum samples determined by this method showed a good correlation with those determined by an ordinary spectrophotometric method using PEG-modified enzymes and peroxidase or by a conventional precipitation method.
Levels of 24,25-Dihydroxyvitamin D3, 25-Hydroxyvitamin D3 and 25-Hydroxyvitamin D3 3-Sulphate in Human Plasma
Authors: Higashi T , Mitamura K , Ohmi H , Yamada N , Shimada K , Tanaka K , Honjo H
Published: February 2014

The concentrations of (24 R)-24,25-dihydroxyvitamin D3 [24,25(OH)2D3], 25-hydroxyvitamin D3 [25(OH)D3] and its 3-sulphate [25(OH)D33S] in the plasma of healthy subjects, patients with chronic renal failure, patients with climacteric syndrome, pregnant women and foetuses were determined using the enzyme-linked immunosorbent assay and high-performance liquid chromatography. 25(OH)D33S was not detected in about one-third of the plasma samples from patients with chronic renal failure ( n = 26). The three metabolites in maternal plasma reached the highest levels in the second trimester of pregnancy followed by a decrease to the values obtained in the first trimester. Older healthy women (age range 44–71 years) showed higher levels of 24,25(OH)2D3 and 25(OH)D3 in the plasma than did young healthy women (age range 21–29 years), whereas no clear difference was observed between the older healthy women and patients with climacteric syndrome. The level of 25(OH)D33S in the plasma was higher in the latter patients than in healthy women.
The Portable Laboratory: An Evaluation of the Accuracy and Reproducibility of i-STAT©
Authors: Bingham D , Kendall J , Clancy M
Published: February 2014

The i-STAT© point-of-care testing analyser, which utilizes single-use multisensor cartridges, was evaluated. Two cartridges were assessed: the 6+ and the G3 +, which provide results for urea, glucose, sodium, potassium, chloride, haematocrit, pH, PCO2, PO2 and various calculated parameters. The results for all analytes agreed well with the analysers in routine use in the laboratory. The reproducibility was comparable even when analysis was carried out by a nurse with only 5 min training. The system was found to be reliable, easy to use and required no maintenance (only a 2-min daily check of the electronics). These features, together with portability and the storage capacity for results, make the i-STAT suitable for point-of-care use, particularly in critical care units.
Measurement of Urinary Amino Acids Using High-Performance Liquid Chromatography Equipped with a Strong Cation Exchange Resin Pre-Column
Authors: Hara Katsuko , Hijikata Yasuyo , Hiraoka Etsuko , Ogawa Noboru , Takahashi Hakuo
Published: February 2014

We determined the urinary amino acid concentrations by high-performance liquid chromatography (HPLC) using an eluent buffer which had been processed through a column packed with strong cation-exchange resin. With this column, ghost peaks resolved or much reduced in size and shifted to a post-arginine position. A clearer separation of peaks of urinary amino acids and ammonia was obtained. This could be due to the elimination of O-phthalaldehyde reactive substances in the eluent by the resin column. This method does not require a separate step to remove ammonia, unlike most of the methods currently used, and thus saves time.
Behaviour of Urinary Dipeptidase in Patients with Chronic Renal Failure
Authors: Fukumura Yukihito , Kera Yoshio , Oshitani Setsuko , Ushijima Yoshio , Kobayashi Isao , Liu Zhen , Watanabe Takashi , Yamada Ryo-Hei , Kikuchi Hideya , Kawazu Shouji , Yabuuchi Masahiko
Published: February 2014

Renal dipeptidase (EC 3.4.13.19) activity in serum and urine from healthy volunteers ( n = 20), patients with diabetes ( n = 18) and patients with chronic renal failure ( n = 5) was measured using glycyl-d-alanine as substrate. The assay was highly specific for the enzyme and was not affected by the various aminopeptidases present in serum and urine. No difference in serum renal dipeptidase activity was observed between the groups. The enzyme activity (U/L) in urine was higher than that in serum, irrespective of the group, suggesting the urine concentration was not affected by the serum concentration. The mean renal dipeptidase activities in urine were 2·56, 2·46 and 0·78 U/mol creatinine for healthy subjects, patients with diabetes and patients with chronic renal failure, respectively. The renal dipeptidase activity was significantly lower in the chronic renal failure group. The urinary excretion of dipeptidase (U/mmol creatinine) showed significant inverse correlations with that of β2-microglobulin, albumin and α1-microglobulin, and with serum concentrations of creatinine, β2-microglobulin and α1-microglobulin. We suggest that urine dipeptidase may be a useful marker of renal diseases.
Evaluation of Six Erythropoietin Kits
Authors: Marsden J T , Sherwood R A , Peters T J
Published: February 2014

Six erythropoietin (EPO) measurement kits from different manufacturers were evaluated for ease of use and performance. Reference values were compared from patient samples with normal and abnormal circulating serum EPO. The kits evaluated were EPO- Trac RIA, EPORIA, DSL RIA, EPO EIA, IBL ELISA and Medac ELISA (see below for manufacturers' details).

The radioimmunoassay (RIA) methods were simple to perform with little preliminary preparation of reagents but the non-isotopic methods were of varying degrees of complexity. Imprecision data showed that performance of the RIA methods was acceptable across the range 40–150 mU/mL [within-assay coefficient of variation (CV) = 2–5%, between-assay CV = 3–7%] but poor (CV > 10%) at the lower end of the range (10–15 mU/mL). The IBL enzyme-linked immunosorbent assay (ELISA) kit showed good precision across the range 10–54 mU/mL (within-assay CV = 5–7%, between-assay CV = 8–12%). The performance of the EPO enzyme immunoassay (EIA) and Medac ELISA were acceptable although precision was poor at the lower end of the range (< 10 mU/mL; within-assay CV 10% and 17% and between-assay CV 13% and 18%, respectively).

The ELISA and EIA methods had lower limits of detection (0·4–0·8 mU/mL) than the RIA methods (2·3–3·6 mU/mL).

Analysis of serum EPO measurement variation between methods showed evidence of significant negative bias with DSL RIA and Medac ELISA when compared with EPO- Trac RIA. Conversely, EPORIA showed significant positive bias and the two remaining methods, EPO EIA and IBL ELISA, showed no evidence of systematic bias when compared with EPO- Trac RIA. Patients with normal circulating concentration of serum EPO gave values that were within the reference range of the kits.
Monitoring of Cardiac Troponin I in Patients with Acute Heart Failure
Authors: Chen Yi Ni , Wei Jian Rui , Zeng Li Jian , Wu Min Yi
Published: February 2014

Cardiac troponin I (cTnI) and creatine kinase MB isoenzyme (CK-MB) were measured in the plasma of 37 patients with acute heart failure. Elevated plasma cTnI concentrations were found in 89% of acute heart failure patients ( P < 0·001) compared with a normal population), while plasma CK-MB showed no significant difference ( P = 0·09). During follow-up, serial measurements of cTnI and CK-MB were performed. In acute heart failure patients, improvement of the clinical profile was associated with declining cTnI concentrations, while deterioration of heart function was closely related to increasing cTnI. Plasma CK-MB activities remained within the normal range throughout the observation period. This preliminary study provides evidence of cardiac damage to functionally overloaded myocytes. cTnI may be a sensitive marker both for early detection of myocyte damage and for monitoring of function in patients with acute heart failure.
Correlation of Marker Values in Down's Syndrome Screening: The Effect of Dating Error
Authors: Dunstan F D J , Iies T C , Nix A B J , Williams K
Published: February 2014

Central to any screening algorithm for Down's syndrome are the values used for the parameters in the multivariate Gaussian statistical model that is used to describe the joint distribution of the marker values. There has been much discussion about the values of the means and standard deviations which are appropriate but little interest has been shown in the values of the correlation coefficients between markers. There has been some speculation that the range of parameter values quoted in the literature arises from factors such as storage of samples, between-assay effects and differences in assay methodologies. We show that gestational dating error, among other factors, could be responsible for much of the variation that is present in quoted parameter values, though the factors mentioned above clearly have an effect.