bluuebunny/crossref_metadata_2025 huggingface dataset:
Retinol Binding Proteinuria and Phosphaturia: Markers of Paracetamol-Induced Nephrotoxicity
Authors: Florkowski C M , Jones A F , Guy J M , Husband D J , Stevens J
Published: February 2014

The occurrence of hypophosphataemia in paracetamol overdose suggests that nephrotoxicity is common, impaired renal tubular reabsorption of phosphate indicating renal damage. To investigate the potential nephrotoxicity of paracetamol, we studied 148 consecutive patients with paracetamol overdose. Serial clinical and biochemical measurements were made, and a fasting overnight urine collection was obtained for creatinine (Cr), phosphate and retinol-binding protein (RBP) determination. Renal threshold phosphate concentration (TmPO4/GFR) was determined from urinary parameters by an established nomogram. The degree of hypophosphataemia correlated with the severity of overdose, and with TmPO4/GFR. The median RBP/Cr ratio was higher in those patients exhibiting biochemical hepatotoxicity compared with those without hepatotoxicity, in whom median RBP/Cr was not significantly higher than controls. Within the group of patients showing biochemical hepatotoxicity, there was a correlation between log RBP/Cr and TmPO4/GFR. RBP/Cr ratio is a less sensitive marker of renal tubular toxicity than phosphaturia in these patients, and may indicate a different mechanism of toxicity.
Establishing Reference Total Serum Cholesterol Values for Saudi Children
Authors: Rafii Ziad S , Al Nasser Abdul Aziz , Budair Afif , Tufail Mohammed
Published: February 2014

Total serum cholesterol was measured in 1320 normal Saudi children aged 0–14 years. The result was 3·88 (0·83) mmol/L [mean (SD)] and there was no statistical difference between girls and boys. Results were lowest in the 0–4 year age group and highest in the 5–9 year age group. Percentile values were established for three age groups and compared with those published for American children; no statistical differences were observed. Unlike other developing countries Saudi children do not have lower serum cholesterol than their western counterparts. We believe that these findings reflect changing dietary habits and increasing affluence in Saudi Arabia.
Re-Evaluation of Conditions Required for Measurement of True Alanine:Glyoxylate Aminotransferase Activity in Human Liver: Implications for the Diagnosis of Hyperoxaluria Type I
Authors: Horváth V Andy P , Wanders Ronald J A
Published: February 2014

In this paper we studied the glyoxylate-dependent transamination of L-alanine and L-glutamate in human liver homogenates in order to develop a reliable method for the determination of true alanine:glyoxylate aminotransferase activity in liver homogenates from patients suspected to suffer from hyperoxaluria type I. Measurements were made according to two protocols described in literature in control human liver homogenates which were either untreated or treated with an antiserum raised against purified alanine:glyoxylate aminotransferase. The results obtained show that enzyme activity can best be determined at pH 8.0 as compared to pH 7.4 since the former leads to a higher sensitivity of the method. Alanine:glyoxylate aminotransferase activities measured at pH 8.0 are approximately 50% higher compared to the enzyme activities measured at pH 7.4. Accordingly, it is proposed to measure alanine:glyoxylate aminotransferase activity at pH 8.0 using the newly determined correction factor as described in this paper.
First Trimester Biochemical Screening for Trisomy 21: The Role of Free Beta hCG, Alpha Fetoprotein and Pregnancy Associated Plasma Protein A
Authors: Spencer K , Aitken D A , Crossley J A , McCaw G , Berry E , Anderson R , Connor J M , Macri J N
Published: February 2014

The potential efficacy of screening for trisomy 21 in the first trimester, using maternal serum markers α fetoprotein, free β human chorionic gonadotropin, unconjugated oestriol and pregnancy associated plasma protein A, was studied in an unselected population of women between the seventh and fourteenth week of gestation. Using a combination of α fetoprotein and free β human chorionic gonadotropin, 53% of affected pregnancies could be identified at a false positive rate of 5%. Unconjugated oestriol and pregnancy associated plasma protein A levels were lower in cases of trisomy 21, but their inclusion with other markers did not significantly improve detection rate. Monitoring the same pregnancies also in the second trimester showed that screening in the first trimester identified the same cases as in the second. We conclude that first trimester screening using free β human chorionic gonadotropin and α fetoprotein, is a viable possibility and will lead to detection rates in excess of 50%. Prospective studies are needed to confirm these observations.
Drugs of Abuse Screening in the West Midlands: A 6 Year Retrospective Survey of Results
Authors: George S , Braithwaite R A
Published: February 2014

We describe the results of urinary drugs of abuse screening performed by the West Midlands Regional Laboratory for Toxicology, Birmingham, UK, on more than 27 800 urine specimens received between January 1988 and December 1993. The number of specimens positive for amphetamine declined from 1988 to 1990, but this was followed by a doubling of specimens testing positive from 5·7% in 1990 to 12·0% in 1993. There is very little evidence of methamphetamine or Ecstasy abuse in the West Midlands. Morphine (assumed to be from heroin abuse) is the most common opiate detected, with 11·7% of all specimens received proving to be positive in 1993. The incidence of cocaine abuse is low, less than 5% when requests are based on clinical judgement, and less than 3% in the overall population monitored.
A Novel Method for Concentrating Urinary Type IV Collagen Based on Precipitation with Polyethylene Glycol: Application to Its Measurement by Enzyme Immunoassay
Authors: Banu Nazifa , Hara Hitoshi , Kataoka Shinkuro , Egusa Genshi , Yamakido Michio
Published: February 2014

We investigated the efficacy of polyethylene glycol (PEG) for effective and reproducible concentration of urinary type IV collagen prior to measurement by enzyme immunoassay (EIA). Human placental type IV collagen at low concentrations (5 and 10μg/L) and urinary type IV collagen were readily precipitated by PEG-4000 added at a concentration of about 150 g/L in the presence of 0·5 g/L γ-globulin. Type IV collagen measurement by EIA from PEG-concentrated urine samples showed complete recovery and good reproducibility. Analysis of size distribution by Sephacryl S-300HR gel chromatography and Western blotting following polyacrylamide gel electrophoresis confirmed that type IV collagen in PEG-concentrated urine samples was of high molecular weight comparable to that of human placental type IV collagen. After PEG concentration, type IV collagen was detectable by EIA even in the urine of healthy subjects. Significantly higher concentrations of urinary type IV collagen were found in 30 diabetic patients with nephropathy than in 20 healthy subjects [99·5 (8·9)μg/L, mean (SEM) versus 21·4 (2·6)μg/L, P<0·0001].

Thus, urinary type IV collagen can be measured effectively by EIA following concentration with PEG. This method has potential for the assessment of the progression of diabetic nephropathy.
Studies on Paracetamol Binding to Serum Proteins
Authors: Milligan T P , Morris H C , Hammond P M , Price C P
Published: February 2014

There is a limited amount of data on the binding of paracetamol to plasma proteins. It has been suggested that binding might influence the ability of some analytical methods to quantify the total amount of drug present in the plasma fraction—the basis of clinical experience in risk assessment and antidote usage. We have investigated the binding of paracetamol to plasma proteins using an ultrafiltration technique. In overdose and spiked uraemic plasma samples the mean percentage of paracetamol bound was 24·1 (1SD = 7·0) with no significant correlation with drug levels or degree of uraemia. There is a small but significant increase in binding with increasing serum albumin concentration both in plasma ( rs = 0·549, P = 0·014) and in pure serum albumin solutions ( rs = 0·848, P < 0·001).
Bisalbumin (Fast and Slow Type) Induced by Human Pancreatic Juice
Authors: Kobayashi Sachiko , Okamura Naotaka , Kamoi Kyuzi , Sugita Osamu
Published: February 2014

To clarify the relationship of pancreatic juice to bisalbumin, we examined the effects of human pancreatic juice and pancreatic proteolytic enzymes on human serum albumin. Electrophoresis showed that a fast-moving band and an increased component of α1-globulin appeared after incubation of serum with pancreatic juice. These components were shown to be albumins by immunofixation and Immunoelectrophoresis. The α1-component increased after incubation of serum with trypsin, and was confirmed as a slow-type albumin by immunoelectrophoresis. Fast-type albumin was observed after incubation of serum with chymotrypsin, and carboxypeptidases A and B. In all patients with pancreatic ascites, the fast- and slow-type albumins were seen in serum and ascitic fluid. Bisalbumins appeared in ascites at higher concentrations than in serum, and disappeared after surgical or conservative treatment. The results demonstrate that human pancreatic juice can produce fast-and slow-type albumins by proteolytic enzymes, and they are seen in patients with pancreatic ascites.
Determination of Aluminium in Serum, Dialysate Fluid and Water by Inductively Coupled Plasma Optical Emission Spectrometry
Authors: Lyon T D B , Cunningham C , Halls D J , Gibbons J , Keating A , Fell G S
Published: February 2014

Methods for the determination of aluminium in serum, dialysate fluid and water by inductively coupled plasma optical emission spectrometry are described and validated. Aluminium was measured at 167 nm using an argon purged monochromator. Matrix effects in serum and dialysate fluid were overcome by using an yttrium internal standard. Serum was found to have a complicated background in the region of 167 nm: Careful selection of the wavelength used for background correction is therefore a pre-requisite for accurate analysis. The method for serum was validated by comparison with electrothermal atomization atomic spectrometry and the limit of agreement determined to be ±0·3 μmol/L. Routine performance in a quality assessment scheme has been highly satisfactory for a period of 1 year. The method is ideal for fast and accurate monitoring of patients potentially at risk from aluminium toxicity.
Evaluation of Human IgG Subclass Assays on Beckman Array
Authors: Pressac M , Allouche F , Circaud R , Aymard P
Published: February 2014

Automated immunonephelometric assays were developed to measure human IgG subclasses in serum, on the Beckman Array Protein System (APSR), with sheep antihuman IgG subclass antisera. The interassay imprecision was judged to be satisfactory in each case (CV: IgG,: 2·3%; IgG2: 2·9%; IgG3: 4·0% and IgG4 5·4%). The standard curves were found to be linear in the ranges 1·5–30·0 g/L for IgG1, 1·5–15·0 g/L for IgG2, 0·1–1·0 g/L for IgG3 and 0·1–1·0 g/L for IgG4. The lower limit for quantification of the immunonephelometric assays was 0·50 g/L for IgG1, 0·04 g/L for IgG2, 0·06 g/L for IgG3 and 0·03 g/L for IgG4. We found no antigen excess to at least 60·0 g/L for IgG, and IgG2, 3·5 g/L for IgG3 and 2·0 g/L for IgG4. Nephelometric results correlated with those of radial immunodiffusion (r = 0·96 for IgG1, r = 0·93 for IgG2, r = 0·90 for IgG3 and r = 0·96 for IgG4).

The reaction monitored by the Beckman Array Protein System is easy to perform, rapid and precise. The performance makes the immunonephelometric method suitable for the determination of IgG subclass concentrations in routine analysis.
Cerebrospinal Fluid Interleukin-6 and Its Diagnostic Value in the Investigation of Meningitis
Authors: Hashim I A , Walsh A , Hart C A , Shenkin A
Published: February 2014

We examined the measurement and the diagnostic value of cerebrospinal fluid interleukin-6 (CSF IL-6) in meningitis. The cytokine was measured by bioassay (B9 hybridoma cell line) and by immunoassay (in-house radioimmunoassay). We compared the diagnostic value of CSF IL-6 determination with that of other biochemical markers of meningitis.

Although there was significant correlation between bioactive and immunoactive IL-6 ( r = 0·724, P < 0·001), results were frequently different with biological/immunological ratios ranging from 0·2 to 24·3 (mean 4·6). Gel permeation chromatography suggested that the discrepancy in biological and immunological activities was not due to molecular heterogeneity, but may be explained by the presence of a synergistic factor. Interleukin-6 concentration was markedly elevated in CSF from most patients with bacterial meningitis compared to patients with viral meningitis and those without evidence of infection. However, low IL-6 levels by radioimmunoassay did not exclude bacterial meningitis (sensitivity 86%). CSF total protein and CSF glucose were significantly different between all three groups, but there was no significant difference in lactate concentration between virally infected and normal CSF, both of which had lower lactate concentrations than those in bacterial infection.

CSF IL-6 measurement had greater sensitivity, specificity and predictive value than these other biochemical markers, and hence a rapid assay for IL-6 in CSF may contribute to the early diagnosis of bacterial infection.
The Effect of Anticoagulant Choice on Apparent Total Antioxidant Capacity using Three Different Methods
Authors: Goode Helen F , Richardson Norma , Myers David S , Howdle Peter D , Walker Barry E , Webster Nigel R
Published: February 2014

We assessed total antioxidant capacity using three different methods, in plasma samples treated with either EDTA or heparin as anticoagulant, from 26 healthy subjects. Total antioxidant capacity was determined using an oxygen electrode (as the total peroxyl radical-trapping antioxidant parameter), by enhanced chemiluminescence, and by measurement of the antioxidant-mediated quenching of the absorbance of a radical cation. The choice of anticoagulant had a profound effect on antioxidant capacity with heparinized plasma giving consistently higher values than plasma anticoagulated with EDTA. Using the oxygen electrode the mean value was 786·5 ± 171·5 μmol/L (heparin) compared to 681·4 ± 160·4 μmol/L (EDTA, P < 0·01). The chemiluminescence technique gave a mean antioxidant capacity of 915·6 ± 214·1 μmol/L in heparin samples and 714·4 ± 195·4 μmol/L in EDTA samples ( P < 0·0001). The absorbance quenching technique gave a mean value of 867·0 ± 199·2 μmol/L (heparin) and 675·5 ± 245·4 μmol/L (EDTA, P < 0·001). All methods tested showed comparable results for EDTA plasma, but the chemiluminescence technique gave higher apparent antioxidant capacity than either of the other two techniques when heparin plasma was used.

We suggest that either heparin is interacting to enhance antioxidant protection perhaps through release of superoxide dismutase, or the chelation of metal ions by EDTA is limiting the activity of antioxidant metalloenzymes. Consistency in the choice of anticoagulant is clearly extremely important.
Serum Glycated Lipoproteins in Type II Diabetic Patients with and without Complications
Authors: Yeğin Ayşenur , Özben Tomris
Published: February 2014

The extent of lipoprotein glycation was assessed in 82 patients diagnosed as diabetes mellitus type II. Glycated lipoprotein levels in serum were determined by agarose gel film electrophoresis in 48 non-diabetic control subjects, 56 diabetics with complications and 26 diabetics with no complications. All glycated lipoproteins were higher in the patients when the diabetics were compared to the control group, but glycated very low-density lipoprotein (VLDL) was the only glycated lipoprotein fraction that was observed to be higher in the diabetic patients with complications compared to the patients without complications ( P < 0·01). Triglycerides and VLDL-cholesterol were also increased in the diabetics, but there was no significant difference in these variables when the patients without complications were compared to the control subjects. There was no difference in total cholesterol and low-density lipoprotein (LDL)-cholesterol levels of the diabetic patients compared to the controls.
Testing for Haemochromatosis in the Diabetic Clinic
Authors: George D K , Evans R M , Crofton R W , Gunn I R
Published: February 2014

Random serum transferrin saturation (TS) was measured in 1194 patients attending a diabetic clinic. Twenty-one patients had TS > 55,% and in three of these patients repeat random TS was < 55%. Seventeen patients were recalled for fasting serum TS and ferritin measurement. Ten patients had fasting TS > 55%. The diagnosis of haemochromatosis was confirmed by liver biopsy in a total of six patients, three of whom were previously unsuspected. Haemochromatosis was the possible diagnosis in a further four patients. Family studies using HLA typing confirmed haemochromatosis in four family members, three of whom were asymptomatic. We conclude that measurement of TS is a simple and effective method of finding cases of haemochromatosis in the diabetic clinic.
External Quality Assessment of Techniques for Assay of Serum Ethanol
Authors: Wilson J F , Barnett K
Published: February 2014

Ethanol was assayed by an average of 200 participants in the UK National External Quality Assessment Scheme, in 26 samples of human serum containing 0·1% fluoride/oxalate and added ethanol from 0·2 to 4·5 g/L. Outliers greater than three standard deviations from the consensus mean for any sample were excluded. Data remaining were grouped by technique and the technique mean and standard deviation calculated. Inter-laboratory variation of 13 technique groups was assessed by the coefficient of variation of measurements and bias from the per cent difference of the technique mean from the target value. Gas chromatography (GC) with packed columns and Sigma alcohol dehydrogenase assay protocols that included a sample deproteinization step, showed better between-laboratory agreement but greater bias. The least variable techniques were headspace analysis with GC-packed columns, Kodak Ektachem, bioMérieux and DuPont aca assays. A significant negative bias was produced by Kodak Ektachem and a positive bias by the Lion alcometer which was the most variable technique.
Routine Therapeutic Monitoring of Lamotrigine in Epileptic Patients Using a Simple and Rapid High Performance Liquid Chromatographic Technique
Authors: George S , Wood A J , Braithwaite R A
Published: February 2014

We have developed a simple and rapid high performance liquid chromatographic technique to determine lamotrigine concentrations in epileptic patients and validated it using external quality control material. The method has been used to monitor the lamotrigine concentration in 70 specimens from 61 patients. Only 50% of the specimens had concentrations within the proposed target range of 1 mg/L to 4 mg/L, and there was no relationship between lamotrigine concentration and age, sex, other anti-epileptic treatments, or dose, although this could in part be explained by concomitant anti-epileptic therapy. We suggest that lamotrigine should be monitored therapeutically in order to assess its efficacy and audit its use as an anti-epileptic treatment, especially with the introduction of this relatively new drug as monotherapy.
High-Performance Liquid Chromatographic Determination of Pyridinium Crosslinks in Serum, Urine and Dialysate of Patients in Chronic Renal Failure
Authors: Ibrahim Suhaila , Mojiminiyi Segun , Barron Jeffrey L
Published: February 2014

This study describes an isocratic reversed phase high-performance liquid chromatographic method for the analysis of pyridinium crosslinks in serum, urine and dialysates obtained from patients with chronic renal failure on haemodialysis.

The mean (SD) urine pyridinoline (PYD) and deoxypyridinoline (DPD) to creatinine (Cr) ratio in 19 healthy volunteers was 28 · 9 (6 · 3) and 9 · 1 (3 · 6) μmol/mol, respectively. In the 22 patients the PYD/Cr and DPD/Cr ratio was 244·6 (436·5) and 66·5 (116·8)/μmol/mol, respectively. The mean serum PYD concentration in 29 patients of 268 · 5 (334 · 4) nmol/L was significantly higher than that of 5 · 9 (1 · 5) nmol/L found in normal volunteers: the mean DPD concentration was 82·9 (93·7) nmol/L in the patients but was undetectable in the serum from the normal volunteers. The concentration of crosslinks in pre-dialysis serum samples was higher than those found post-dialysis reflecting a significant removal of the crosslinks during dialysis. The assay of pyridinium crosslinks in serum, urine and dialyses fluid could potentially provide evidence of bone collagen turnover in patients in renal failure. Their measurement in serum and dialysate could be particularly useful in anuric patients.
Adjustment of Serum Total Calcium for Albumin Concentration: Effects of Non-Linearity and of Regression Differences between Laboratories
Authors: Barth J H , Fiddy J B , Payne R B
Published: February 2014

It has been reported that the relationship between serum total calcium and albumin concentrations in hospital patients deviates from linearity at low albumin concentrations. We searched a large laboratory computer data base for adult patients with discretionary requests for serum calcium analysis but with no other data suggestive of disturbances of calcium homeostasis, and collected a minimum of 100 calcium values at each of a wide range of albumin concentrations. We confirmed the earlier observation, but found that the use of a single regression to derive an adjustment of total calcium for albumin gave only small differences of no clinical significance.

To investigate whether equations to adjust total calcium for albumin can be transferred between laboratories, three laboratory computers were searched for calcium requests from patients likely to have a low prevalence of calcium disturbances. The regressions of total calcium on albumin differed significantly between laboratories, but within each laboratory gave adjusted calcium values identical with those in health. Although the errors resulting from applying an equation from one laboratory to another were small and unlikely to be of major clinical significance, we recommend that where possible laboratories should derive adjustment equations from their own data.
The Use of the Short Tetracosactrin Test for the Investigation of Suspected Pituitary Hypofunction
Authors: Wang T W M , Wong M S , Smith J Falconer , Howlett T A
Published: February 2014

The short Synacthen (tetracosactrin) test (SST) is an established method of assessing adrenocortical reserve, and is increasingly replacing the insulin tolerance test (ITT) for the assessment of the hypothalamic-pituitary-adrenal (HPA) axis. However, there is no consensus on how the test is performed, and various time points and routes of administration are used. The present study was done, first, to determine whether there was any difference in cortisol responses when Synacthen was administered intramuscularly compared with intravenously and, secondly, to compare cortisol responses at 30 and 60 min. We found no significant difference between the two routes of administration. However, cortisol responses at 60 min were significantly higher than at 30 min ( P < 0·05). Previous validations for the use of the SST in place of the ITT have used cortisol responses 30 min after Synacthen. We conclude that where the SST is used to assess the HPA axis, cortisol response at 30 min after intravenous Synacthen should be used.
Measurement of Bone-Specific Alkaline Phosphatase by an Immunoselective Enzyme Assay Method
Authors: Hata Keishi , Tokuhiro Hisako , Nakatsuka Kiyoshi , Miki Takami , Nishizawà Yoshiki , Morii Hiroyo , Miura Masakazu
Published: February 2014

We evaluated a new immunoselective enzyme assay of bone-specific alkaline phosphatase (ALP). The monoclonal antibody used in this assay was raised against purified bone-specific ALP obtained from SAOS-2 human osteosarcoma cell line. Calibration was based on the enzyme's own activity. The relative activity of the antibody was 100% with bone ALP, 8·7% with liver ALP, and 0% with placental and intestinal ALPs. Intra- and inter-assay coefficients of variation were less than 4%. The sensitivity of the assay was 0·7 U/L, and the linearity extended from 2 to 140 U/L. The recovery of bone-specific ALP standard added to serum was 94–106%. The correlation coefficient between this method and the polyacrylamide gel (PAG) electrophoretic method was 0·94. The mean value of bone-specific ALP in 89 healthy adults (mean age 29 years, SD 5 years) was 18·5 U/L (SD 4·1 U/L). Interestingly, mean bone-specific ALP activities in 60 premenopausal women (mean age 39 years, SD 8 years) and 70 postmenopausal women (mean age 57 years, SD 5 years) were 20·3 U/L (SD 6·5 U/L) and 31·1 U/L (SD 11·1 U/L), respectively. The age-related increase in bone-specific ALP was significant and more pronounced in women ( P < 0·01). We conclude that this new immunoassay of bone-specific ALP would be useful for clinical investigation of patients with osteoporosis or other metabolic diseases of bone.
Detection of Bence-Jones Protein in Serum by Immunoblotting
Authors: Backer E T , Brand A
Published: February 2014

To detect Bence-Jones protein (BJP) in serum we precipitated intact immunoglobulins (Ig) using polyethylene glycol (PEG) and subjected the BJP in solution to electrophoresis in agarose gel, followed by transfer to a polyvinylidene difluoride membrane, and immunoenzymatic staining (successively using rabbit anti-human light/heavy chain of Ig, biotinylated swine anti-rabbit Ig, and alkaline phosphatase-conjugated streptavidin). Treatment with PEG effectively reduced background staining of polyclonal Ig in the immunoblots, although intact monoclonal Ig was not always completely removed. To compare the present method with immunoelectrophoresis (IEP), we selected samples from patients demonstrating BJP by IEP in both serum and urine ( n = 40), serum only ( n = 18), and urine only ( n = 32); 21 of these patients had BJP alone and 69 had BJP in addition to intact monoclonal Ig. Efficiency of detection of BJP in serum was increased by the present method: Serum BJP was detected in 70 patients by the present method versus 58 by IEP. The present method demonstrated single BJP bands in the samples from 16 patients (κ, n = 7; λ, n = 9) and multiple BJP bands (range: 2–9) in the samples from 54 patients (κ, n = 31; λ, n = 23). This method could be useful for detecting BJP in serum from patients suspected of having light chain gammopathy (without the need for urine testing) and may complement urine testing in patients excreting polyclonal free light chains of Ig.
Early ‘Rule-In’ Diagnosis of Acute Myocardial Infarction 4 h Post Admission for Rapid Risk Stratification by Creatine Kinase Increment (Creatine Kinase Change)
Authors: Collinson P O , Stubbs P J
Published: February 2014

The use of creatine kinase (CK) measurement on admission, CK at 4 h, percentage CK change and electrocardiography (ECG) were compared for early risk stratification in the diagnosis of acute myocardial infarction (AMI). A total of 248 patients (median age 62 years, range 26–84) were studied (187 men, 61 women) of whom 118 had a final diagnosis of AMI. Median time to presentation was 3·92 h (range 0–11·17 h). Overall, the admission ECG had a sensitivity of 72·6% [95% confidence interval (CI) 64·6–80·7] with specificity of 88·9% (CI 83·4–94·4); 4 h CK change had a sensitivity of 100% (CI 96·1–100) with a specificity of 90·4% (CI 83·5–95·1). After excluding those with contraindication to anti-thrombotic therapy there were 109 patients with an uncertain initial diagnosis. In this group, admission CK had a sensitivity of 37·5% (CI 18·8–59·4) with a specificity of 94% (CI 86·8–98·1); 4 h ECG had a sensitivity of 43·8% (CI 19·8–70·1) with specificity of 97·4% (CI 86·5–99·9%); 4 h CK had a sensitivity of 79·2% (CI 57·8–92·9) with a specificity of 96·5% (CI 90–99·3); 4 h CK increment had a sensitivity of 100% (CI 85·8–100) with a specificity of 94% (CI 86·8–98·1). The admission ECG remains the investigation of choice for early ‘rule-in’ diagnosis of AMI for thrombolysis. Admission measurement of CK offers a small advantage in the patient with an uncertain diagnosis but the overall benefit is low. A strategy of admission ECG plus serial testing allows diagnosis to be complete by 4 h for accurate risk stratification. Whether this can be used for selection for therapeutic options (thrombolytic, anti-coagulation, anti-platelet or anti-anginal agents) requires further clinical trials.
Down's Syndrome Screening Using Free βhCG: Instability Can Significantly Increase the Down's Risk Estimate
Authors: Beaman Janine M , Akhtar Naheed , Goldie David J
Published: February 2014

The stability of free βhCG (human chorionic gonadotrophin) was assessed using a dual α-fetoprotein and free βhCG assay. A significant increase in free βhCG concentration was observed in heparinized samples left unseparated for 24 h or more, the mean increase in 21 samples being 10.2% after 24 h ( P = < 0.001), increasing to 45.7% after 96 h. Similar results were also obtained in clotted samples. The effect of the increase in free βhCG on the Down's risk estimate was calculated to assess the impact of delayed sample transport and separation. The Down's risk increased in all samples with increasing separation time, but this was most significant in two samples where, using a cut off of one in 250, the risk classification changed from low risk to high risk. These results suggest that delayed sample separation can have a significant effect on screening programmes using free βhCG, particularly with respect to those patients whose risk classification is changed.
Micro-Extraction of Commonly Abused Benzodiazepines for Urinary Screening by Liquid Chromatography
Authors: Wolff Kim , Garretty Deborah , Hay Alastair W M
Published: February 2014

We have developed a micro-extraction procedure for the analysis of seven commonly prescribed benzodiazepines (chlordiazepoxide, diazepam, lorazepam, nitrazepam, nordiazepam, oxazepam, and temazepam) in urine using liquid chromatography. The method is reliable and sensitive, uses small volumes (100μL) of urine and is suitable for the detection and quantification of low concentrations of benzodiazepines. The micro-extraction procedure allowed rapid sample processing, which is important for routine sample handling. The limit of detection for the seven benzodiazepines ranged from 0·10–0·71 mg/L and recovery of the different benzodiazepines was good, ranging from 70–105%. Between-and within-assay coefficients of variation ranged from 6·3% to 13·8%, and 2% to 3·5%, respectively. Chlordiazepoxide chromatographed poorly (between assay coefficient of variation 35·4%, within-assay 7%), and we set the cut-off value for this compound at 5·0 mg/L.
Evaluation of Bionike One-Step Tests for the Detection of Drugs of Abuse in Urine
Authors: Brown E R S , Jarvie D R , Simpson D
Published: February 2014

Bionike one-step tests were used to screen urine samples for amphetamines, methamphetamines, benzodiazepines, cannabinoids, methadone and opiates, and results were compared with those obtained using enzyme multiplied immunoassay technique d.a.u. assays. Taking into consideration different threshold levels and possible differences in cross-reactivities, there was good agreement between the methods. Results of Bionike tests correlated well with amphetamines, methadone and opiates detected in urine using gas chromatography—mass spectrometry. Bionike methods are rapid, simple to use, and relatively inexpensive for on-site testing of individual drugs or groups of drugs in urine.
Evaluation of a New, Rapid and Automated Immunochemiluminometric Assay for the Measurement of Serum Intact Parathyroid Hormone
Authors: Michelangeli Valdo P , Heyma Paula , Colman Peter G , Ebeling Peter R
Published: February 2014

The Immulite parathyroid hormone (PTH) immunochemiluminometric assay (ICMA) was evaluated by measuring serum PTH concentrations in 134 volunteers and 251 patients with various diseases affecting bone and mineral metabolism and comparing with those measured by the Nichols Allegro immunoradiometric (IRMA) assay.

Although the assays were highly correlated ( r=0·99, P<0·0001), there were discrepancies at lower PTH concentrations which may be explained by the lower limit of detection of the ICMA assay. The anti-coagulants EDTA and heparin appeared to have significant effects on PTH measurement particularly at lower concentrations. Sera assayed by ICMA diluted out more uniformly than in the IRMA and there was no cross reactivity with parathyroid hormone-related peptide in either the IRMA or ICMA. Delays of up to 8 h in specimen handling did not appear to affect PTH measurements.

The enhanced sensitivity of the Immulite ICMA intact PTH assay confers an advantage in the diagnosis of both hyper- and hypocalcaemia, while the shorter incubation times, automation and lack of radioactivity are important practical advantages.
Interassay Differences in Growth Hormone Measurement in Acromegaly
Authors: Barth J H , Smith J H , Clarkson P
Published: February 2014

We measured plasma growth hormone concentrations by three different two-site immunometric assays (Pharmacia hGH RIA, IDS Gamma-BCT and Delfia 22 kDa hGH) to determine whether there are GH isoforms secreted by acromegalic patients that are under-recognized by some assays. There was a fairly good agreement between assays with the IDS Gamma-BCT and Delfia 22 kDa assays giving lower results than the Pharmacia IRMA. GH was measured on stored plasma samples from 24 patients with proven acromegaly. There was a consistent difference between the three assays of approximately 20% of the mean value for each patient.
Interleukin 6 in Cerebrospinal Fluid of Patients with Meningitis is not a Useful Diagnostic Marker in the Differential Diagnosis of Meningitis
Authors: López-Cortés L F , Cruz-Ruiz M , Gómez-Mateos J , Jiménez-Hernández D , Viciana-Fernández P , Jiménez-Mejías E
Published: February 2014

We assayed interleukin 6 (IL-6) concentrations in cerebrospinal fluid (CSF) from patients affected by meningitis of different aetiologies, and verified whether IL-6 can be used as a diagnostic marker in the differential diagnosis of meningitis. We used a monoclonal antibody enzyme immunoassay to test 98 CSF samples classified as pyogenic (15), viral (15), self-resolving aseptic meningitis (20), other infectious meningitis (9), neoplastic (4) and normal CSF from patients with (20) and without (15) non-infectious neurological diseases. CSF IL-6 concentrations were increased in pyogenic meningitis (100%) and in more than 50% of viral and other subarachnoid space infections, and rarely in patients without central nervous system infections. Though patients affected by pyogenic meningitis showed the highest levels of CSF IL-6, only a cut-off point ≥10000 pg/mL was able to discriminate pyogenic meningitis from those of other aetiologies with a specificity ≥94% and a positive predictive value of ≥0·75 but the sensitivity was ≤60%. Therefore, CSF IL-6 concentration is not a good diagnostic marker in the differential diagnosis of meningitis.
Improving the Quality of Near-Patient Blood Glucose Measurement
Authors: Rumley A G
Published: February 2014

The quality of near-patient blood glucose measurement was audited in our hospitals in 1990, when a diversity of glucose meters were in use, by sending three samples of unknown (to the meter user) concentration to each user and collecting and analysing the results produced. The overall performance was unsatisfactory with a mean coefficient of variation (CV) of 23·5%. A scheme involving training, quality control and external quality assurance was introduced in 1993 based on the Bayer Glucometer II meter. This meter was used exclusively throughout our hospitals. Data from the quality assurance scheme showed that the overall CV fell initially to 14–16% and then settled at about 10–12% for the following 2 years. Unacceptable results (those more than two standard deviations from the mean) were 8–12% of the total. A new meter was introduced in 1995 (the Bayer Glucometer 4) which had the advantages of ‘no-wipe’ and automatic timing technology and in the subsequent year overall CV fell to 5–6% and has remained at this level. The frequency of unacceptable results fell to 5–7%. The improved precision figures encouraged us to change criteria for acceptability to mean ±15%. Using these criteria the level of unacceptable results is now 1–2%. This study shows that introducing training, quality control procedures, a quality assurance scheme and improved meter technology all backed by laboratory expertise can produce significant improvement in the quality of near patient blood glucose measurement.
Atypicality or Specific Screen: Which is Better at Detecting Non-Down's Chromosomal Anomalies?
Authors: Reynolds T M
Published: February 2014

I evaluated the value of adding a trisomy 18 screen to routine Down's screening and compared it with the benefits of atypicality screening. I studied 5080 unaffected pregnancies, 144 Down's syndrome and 190 non-Down's syndrome chromosome abnormalities (20 trisomy 13; 79 trisomy 18; 20 Turner's syndrome; 29 other sex chromosome abnormalities; 8 triploidy; and 34 miscellaneous). Using a one in 250 cut off, the Down's screen gave a screen positive rate of 4·07%; addition of atypicality without a trisomy 18 screen gave an extra 0·9% screen positives; trisomy 18 screening without atypicality gave an extra 0·51% screen positives; and atypicality screening after trisomy 18 screening gave 0·52% screen positives. Total screen positive rates were: Down's screening only, 4·07%; Down's screening + atypicality, 4·97%; Down's screening + trisomy 18 screen, 4·58%; Down's screening + trisomy 18 screen + atypicality, 5·09%. The detection rate for Down's syndrome using a one in 250 cut off was 58·9% and with addition of trisomy 18 and atypicality screening this increased to 59·3%, indicating that the extra screens add little to detection of Down's syndrome. For the other chromosomal abnormalities, Down's screening alone detected 22·6% of cases overall and addition of trisomy 18 and atypicality screening increased this to 49%. Examination of the marginal benefits of the extra screening tests revealed that the trisomy 18 screen was better at detecting chromosomal abnormalities than the Down's screen and that it would, therefore, be worthwhile adding this to all screening programs. Atypicality proved to be much less effective and it is suggested that this screen should only be applied in the early days of a screening program until sufficient data is available to design specific screens.
Biological Variation of Cardiac Markers: Analytical and Clinical Considerations
Authors: Ross S M , Fraser C G
Published: February 2014

The analytical, within-subject and between-subject components of variation were estimated for serum total creatine kinase (TCK) activity, CK-MB (creatine kinase-MB) activity, CK-MB mass, ratios of CK-MB activity and CK-MB mass to TCK activity and myoglobin concentration in a cohort of 16 apparently healthy subjects over 5 days. Analytical goals based on biological variation showed that, for all quantities except CK-MB mass, methodological improvement is warranted. All cardiac markers showed marked individuality which casts doubt on the utility of conventional population-based reference values as interpretative criteria. The critical differences required for significance of changes in serial results differ markedly from marker to marker and the data allow generation of objective criteria for monitoring individuals.
The Assessment of Platelet Derived Growth Factor Concentration in Post Myocardial Infarction and Stable Angina Patients
Authors: Wallace J M W , Freeburn J C , Gilmore W S , Sinnamon D G , Craig B M , McNally R J , Strain J J
Published: February 2014

Platelet derived growth factor (PDGF) has been implicated in the pathogenesis of atherosclerosis. PDGF is released by aggregating platelets and monocytes which gather around sites of arterial injury. In the study reported here the concentration of plasma PDGF was measured in post myocardial infarction (MI) patients ( n = 28), angina patients ( n = 25), and control subjects ( n = 27). Venous blood samples were taken and the concentration of PDGF determined by an enzyme linked immunosorbent assay (ELISA). Plasma PDGF concentrations were significantly higher in the post MI group compared to both the control and angina groups ( P ≤ 0.05). The increase in PDGF concentration may be due to increased activation of platelets or monocytes since these two cells are major sources of plasma PDGF. High concentrations of PDGF in the circulation could further accelerate the progression of the disease.
Oxidative Stress of Vanadium-Mediated Oxygen Free Radical Generation Stimulated by Aluminium on Human Erythrocytes
Authors: Abou-Seif M A M
Published: February 2014

It has been suggested that aluminium stimulates vanadium-mediated superoxide radical generation. The oxidative stress of generated superoxide radicals on antioxidant enzyme activity, oxidation of NADH and NADPH, membrane lipid peroxidation and osmotic fragility in human red blood cells (RBC) was investigated. RBC were incubated with varying concentrations of vanadium and aluminium ions at 37°C for 2 h. RBC incubated with vanadium ions showed significantly increased superoxide dismutase and catalase activities, and oxidized NADH and NADPH concentrations compared with control RBC preparations. Erythrocyte lipid peroxidation was assessed by measuring thiobarbituric acid reactivity. RBC incubated with elevated levels of vanadium showed significantly increased membrane lipid peroxidation when compared with control RBC; it increased further on addition of aluminium. A significant positive correlation was observed between the extent of vanadium induced membrane lipid peroxidation and the osmotic fragility of treated RBC.

In the presence of vanadium, aluminium stimulates superoxide dismutase and catalase activities, NADH and NADPH oxidation and membrane lipid peroxidation, as well as increasing osmotic fragility of human erythrocytes. The stimulatory effect of aluminium was dependent on concentration. These results may have implications for the mechanism of toxicity of aluminium and vanadium in haemodialysis patients.
Glucose Interference in the Pancreolauryl Test
Authors: Trewick A L
Published: February 2014

The influence of the glucose concentration in urines being assayed as part of a pancreolauryl test was investigated. Paired patient urines ( n = 5) were assayed at 60° and 70°C, before and after spiking to 5% glucose. The influence of assay temperature alone was assessed using glucose-free paired patient urines ( n = 10). Aqueous glucose solutions and spiked (5% glucose) normal random urines ( n = 5) were assayed to assess the effect of glucose concentration alone.

There was no difference in T/K ratios for glucose-free patient samples at 60°, 70° and 80°C. After spiking with glucose T/K ratios were significantly different when assayed at 70°C, but not when assayed at 60°C. Aqueous glucose solutions ≥ 0.6% produced a pigment at temperatures ≥ 65°C which absorbed at the λmax of fluorescein.

Glucose was found to interfere in the pancreolauryl test. Caution should be exercised when interpreting results from glucosuric samples.
A Comparison of Automated Fructosamine and HbA1c Methods for Monitoring Diabetes in Pregnancy
Authors: Kennedy David M , Johnson Andrew B , Hill Peter G
Published: February 2014

Two automated methods for measuring fructosamine (Test Plus and the original fructosamine assay) and glycated haemoglobin (Tina-quant immunoassay) were compared to determine which is the best index of blood glucose control during pregnancy. Thirteen women with type 1 diabetes were studied, with four-weekly measurements of HbA1c and fructosamine Test Plus using a Hitachi 911 analyser and fructosamine measured using an Olympus AU800 analyser. HbA1c correlated better ( r = 0.573) with mean blood glucose (MBG) concentration than did fructosamine Test Plus ( r = 0.347), even after correction for total protein concentration ( r = 0.463), while there was no significant correlation with the original fructosamine method ( r = 0.201). HbA1c correlated better with fasting/pre-prandial MBG concentrations, whereas fructosamine Test Plus correlated better with post-prandial MBG concentrations. Fructosamine Test Plus decreased with gestational age, and correlated with albumin and total protein concentrations, whereas HbA1c did not change with gestational age. Thus, HbA1c and fructosamine Test Plus were found to be useful in verifying home blood glucose measurements in diabetic pregnancy, with HbA1c being the best predictor of MBG concentration.
Isolation and Properties of a Novel Phospholipase a from Rat Brain That Hydrolyses Fatty Acids at sn-1 and sn-2 Positions
Authors: Yoshida Hiroshi , Tsujishita Yosuke , Hullin Françoise , Yoshida Kimihisa , Nakamura Shun-Ichi , Kikkawa Ushio , Asaoka Yoshinori
Published: February 2014

A Ca2+-independent phospholipase A that releases various fatty acids from sn-1 and sn-2 positions was partially purified from rat brain soluble fraction. The enzyme showed an approximate molecular mass of 300 kDa on gel filtration column chromatography. Its enzymatic properties are distinct from those of well characterized phospholipase A2 enzymes; by using a series of synthetic phosphatidylcholines, the enzyme cleaved oleic, linoleic, and arachidonic acids like phospholipase A2, and released palmitic and stearic acids like phospholipase A1.

Phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidic acid were hydrolysed with almost equal efficiencies by this enzyme. These results indicate that the enzyme isolated is a novel Ca2+ -independent intracellular phospholipase A that might be responsible for production of various fatty acids from membrane phospholipids.
Cardiac Troponins in Patients with Renal Dysfunction
Authors: Collinson P O , Hadcocks L , Foo Y , Rosalki S B , Stubbs P J , Morgan S H , O'Donnell J
Published: February 2014

Cardiac troponin T (cTnT) and cardiac troponin I (cTnI) were measured in 198 patients with renal dysfunction [132 men: median (range) age 66·1 (8·2-90·3) years]. cTnT was measured by two methods: ELISA and Enzymun (Boehringer Mannheim UK, Lewes, UK), both with a detection limit of 0·05 μg/L in 179 and 78 patients, respectively. cTnI was measured in 80 patients by the OPUS plus and OPUS Magnum systems (Dade-Behring, Milton Keynes, UK) with a detection limit of 0·5 μg/L.

Patients were classified as having chronic renal impairment (CRI), chronic renal failure (CRF), acute renal failure including those with multiple organ failure on renal replacement therapy (ARF), and patients with chronic renal failure treated with haemodialysis (HD). Cardiac troponins were detectable in the serum of patients with renal dysfunction. cTnT was detectable in 113/179 (63·1%) and 33/78 (42·3%) by the ELISA and Enzymun methods respectively. cTnI was detectable in 17/80 (21·3%). cTnT (ELISA and Enzymun methods) and cTnI were detectable with increased frequency in the CRF, HD and ARF patient groups compared with the CRI group. Cardiac troponin concentrations did not correlate with serum creatine kinase (CK) activity, CK-MB, or urea or creatinine levels. Serial cardiac troponin measurements may be required to confirm or exclude a diagnosis of acute coronary syndromes in patients with renal dysfunction.