bluuebunny/crossref_metadata_2025 huggingface dataset:
Variability of Capillary Plasma Glucose in Healthy Individuals in Repeated 75 g Oral Glucose Tolerance Tests
Authors: Cummings S T , Fraser C G
Published: February 2014

A series of ten 75g oral glucose tolerance tests was carried out on each of 14 apparently healthy subjects. The analytical, intra-individual and inter-individual components of variation were calculated by nested ANOVA following duplicate analyses of capillary plasma glucose under optimal conditions. The analyses met the objectively set analytical goal of CV ≤2·2%. There was considerable intra-individual variation, but no subject was ever classified as diabetic or having impaired glucose tolerance. Recent criteria for interpretation of results must be used since conventional population-based reference values are not adequate. Serial results from an individual must differ by more than 0·7 mmol/L for fasting specimens and at least 1·6 mmol/L for other specimens for a statistically significant ( P ≤ 0·05) change to have occurred.
Measurement of Theophylline in Dried Blood Spots by Spectrophotometric Enzyme Immunoassay
Authors: Rattenbury J M , Taylor Tracy
Published: February 2014

A widely-used enzyme immunoassay for the measurement of theophylline in plasma (EMIT) has been adapted for use with dried blood spots. Potential interference from haemoglobin in eluates of the spots was avoided by autoclaving them prior to analysis. The method was investigated in terms of the recovery of theophylline added to samples, precision, and the correlation of results in DBS with those in plasma samples. The recoveries of some other drugs from eluates of autoclaved DBS were also investigated.
An Intra-Erythrocytic Low Molecular Weight Lead-Binding Protein in Acute and Chronic Lead Exposure and its Possible Protective Role in Lead Toxicity
Authors: Lolin Yvette , O'Gorman Patrick
Published: February 2014

A low-molecular-weight protein was measured in erythrocytes from workers with chronic and recent lead exposure, with and without clinical lead toxicity, and from a group of control subjects not exposed to undue environmental lead. The protein was detected in all the workers, but in significantly smaller amounts in those with symptoms, and was absent from controls. The synthesis of the protein is induced at blood lead concentrations above 1·9 μmol/L, but is reduced in workers susceptible to clinical lead toxicity at blood lead concentrations below 4·0 μmol/L. The activity of the red blood cell dithiothreitol (DTT)—activated 5-aminolaevulinate dehydratase (ALA-D) was correlated with the concentration of the low-molecular-weight protein, with both being particularly low in the symptomatic workers.

Previous studies have shown that the protein binds lead. By sequestrating excess lead into a non-toxic form, the protein may have a protective role in preventing clinical, and reducing biochemical, lead toxicity.
Serum Angiotensin Converting Enzyme in Sarcoidosis—Its Value in Present Clinical Practice
Authors: Studdy P R , Bird R
Published: February 2014

Angiotensin converting enzyme (ACE) has a central role in blood pressure homeostasis. It is present in low and fairly constant concentration in the serum and in high concentration in the pulomonary capillary bed.

Unusually high serum angiotensin converting enzyme (SACE) activity is present in active sarcoidosis, an observation now confirmed by many investigators.

In spite of its lack of specificity as a test for sarcoidoisis, SACE provides a good monitor of disease activity which clinicians find useful in the management of patients with sarcoidosis. There continues to be considerable interest in SACE in sarcoidosis and with the recent development of simpler assays, more centres may be expected to offer SACE measurements as a service.

In this paper we discuss the indications for estimating SACE in sarcoidosis and its relevance to current clinical practice.
Alpha-1-Antitrypsin in Liver Disease
Authors: Deam David , Byron Keith , Ratnaike Sujiva
Published: February 2014

Low alpha-1 -antitrypsin (AAT) levels are known to be associated with liver disease. As AAT is also synthesised in the liver, we investigated whether liver disease itself may result in low AAT levels. AAT was measured in plasma from 100 patients with various liver diseases including hepatitis, cirrhosis, jaundice and liver failure. Twenty-eight patients had increased AAT values (greater than 3·;1 g/L), 70 had normal AAT values (between 1·;5 and 3·;1 g/L) and 2 had decreased AAT levels (< 1·;5 g/L). The 2 patients with low AAT levels were found to be of the PiMZ phenotype. There was no significant correlation between any of the standard ‘liver function tests' and the AAT level. Our findings suggest that in liver disease AAT levels are usually normal or increased. Low levels are uncommon and the possibility of an abnormal AAT phenotype being associated with the liver disease should be examined.
Improved Sample Collection Technique for Capillary Blood on Filter Paper for Determination of Glycated Haemoglobin
Authors: Eckerbom Solveig , Bergqvist Yngve
Published: February 2014

A simple and practical method of sampling capillary blood was tested. This method was used for determination of glycated haemoglobin by ion exchange chromatography. Capillary blood was collected onto filter paper and placed in a small polypropylene tube containing phosphate-buffered sodium chloride with EDTA and p-hydroxybenzoic acid methyl ester. There was good correlation between filter paper sampling and conventional sampling in tubes with EDTA as anticoagulant. With this new sampling technique the glycated haemoglobin value was stable for 7 days at room temperature and for at least 10 days at +4°C. Sampling can be performed by the patient at home and the sample then mailed to the laboratory, thus enabling analysis to be performed prior to the patient's visit to the physician.
Determination of Plasma Pyridoxal Phosphate Levels Using a Modified Apotryptophanase Assay
Authors: Edwards Paul , Liu Peter K S , Rose G Alan
Published: February 2014

The development of a simple non-isotopic enzymatic assay for plasma pyridoxal phosphate (PLP) using a modified apotryptophanase procedure is reported. Recovery of added PLP from plasma was 86% and the within-run precision of the assay was 6·;5%. Between-run precision was 7·;5%. Concentrations of cupric ions as low as 20 μmol/L severely inhibited apotryptophanase activity and this effect of copper was almost completely prevented by the addition of EDTA. The reference plasma PLP range obtained by the apotryptophanase method was found to be between 5 and 50 μg/L plasma, with a mean of 17 ± 10 μg/L plasma. The assay requires minimum technical skill and, with the aid of a multisample reaction rate analyser, more than 50 samples could easily be handled within a working day.
Assessment of the Bioactivity of Human and Bovine Thyrotrophin Preparations Using a Porcine Thyroid Cell Bioassay
Authors: Reader S C J , Davison B , Robertson W R , Lambert A
Published: February 2014

The biopotency of six preparations of thyrotrophin (TSH) has been compared in a highly sensitive in vitro porcine thyroid cell bioassay using iodide uptake as an endpoint. Three of these preparations were of human origin and three derived from bovine pituitary tissue. One human TSH preparation, the 2nd International Reference Preparation, 80/558, was used to calibrate the other five. The log dose—log response curves for all preparations were sigmoidal in shape. For the purpose of evaluation the central linear portions of the curves were compared. With all preparations the slopes in this region were very similar. The relative biopotencies of the bovine preparations (unit : unit) were at least five times those of the human standards when measured using the porcine thyroid cell bioassay. These findings emphasise the need to control the TSH standards employed in a variety of bioassays, particularly those used for between-laboratory comparison.
Feasibility of a Short Term Severely Restricted Sodium Diet with Counselling Support
Authors: Panos M Z , Williams Roger
Published: February 2014

For the purpose of short term clinical trials previous studies have made use of metabolic kitchens to provide severely restricted sodium diets. We evaluated the feasibility of administering a 5-day severely restricted (22 mmol) sodium diet on an outpatient basis with counselling support, outside a metabolic unit. In 13 highly-motivated volunteers, 24-h urinary sodium excretion fell from 128·5 ± 11·9 on a normal diet to 19·2 ± 2·88 mmol per day and plasma sodium dropped from 140 ± 0·41 to 137 ± 0·78 mmol/L, showing that such an approach is effective.
An Automated Method for the Analysis of Urinary Free Catecholamines Using Asted and High-Pressure Liquid Chromatography
Authors: Green B , Cooper J D H , Turnell D C
Published: February 2014

A high-pressure liquid chromatography procedure for the measurement of free catecholamines in urine is described. ‘On-line’ sample preparation using a cartesian robot combined with the ASTED™ process ensures minimal operator intervention and reduced costs.
Interference of Plasma Fluorophores on the Red Blood Cell Zinc Protoporphyrin : Haemoglobin Ratio as Determined on a Haematofluorimeter
Authors: Bartels P C , Helleman P W , Soons J B J
Published: February 2014

Direct measurement of the zinc protoporphyrin:haemoglobin ratio (ZPP: Hb ratio) in blood samples is performed by using a haematofluorimeter. Interference by non-specific fluorophores can be eliminated by removing the plasma and making the measurement on washed red blood cells (RBCs). After re-suspending RBCs in isotonic saline, haematofluorimeter readings for the ZPP: Hb ratios revealed higher stability in the course of time whereas a good relationship was found with results obtained by application of an extraction method.

Separate reference ranges were established for adult male and female subjects. After washing, the mean values calculated for ZPP: Hb ratios of subjects belonging to the reference groups demonstrated a reduction of 0·04 μmol ZPP mol Hb, corresponding with approximately 30%. In the patients' group, application of washing resulted in a variable decrease of ZPP: Hb ratios.
New Cancer Markers
Authors: Duffy M J
Published: February 2014

In recent years many new and improved cancer markers have become available. From a clinical point of view, the most useful of the new markers include CA 19–9 for pancreatic adenocarcinoma, CA 125 for epithelial ovarian cancer, CA 15–3 for breast cancer, prostate specific antigen for prostatic adenocarcinoma, placental alkaline phosphatase for testicular seminomas and neuron-specific enolase for small cell carcinoma of lung. None of these new markers are specific for cancer. Furthermore, none are organ specific, except prostate specific antigen for prostatic tissue. The main application of these markers is in monitoring patients with the specific malignancies indicated. Whether routine use of any of these new markers leads to higher quality of life or enhanced survival remains to be determined.
Serum Thyroglobulin—Its Measurement and Clinical Use
Authors: Wilson R , McKillop J H , Jenkins C , Beastall G H , Thomson J A
Published: February 2014

Radioimmunoassays (RIA) have been shown to be unreliable in measuring serum thyroglobulin levels in patients with antithyroglobulin antibodies. The aim of this study was twofold. Firstly to compare the abilities of two immunoradiometric assays (IRMA), one commercially available, the other an ‘in house’ assay, with a conventional RIA. In addition the prognostic value of serum thyroglobulin levels in patients likely to relapse following a course of antithyroid drugs for Graves' disease was examined.

The results obtained showed both of the IRMA methods to be unaffected by the presence of antithyroglobulin antibodies. Serum thyroglobulin levels were found to be poor predictors of relapse or remission following a 12 month course of antithyroid drugs.
Enzyme Immunoassay of Lactoferrin in Newborn Term Infants: Reference Values and Influence of Diet
Authors: Scott P H
Published: February 2014

Plasma lactoferrin is an acute phase protein which may have a variety of roles in the anti-infective process. As the diagnosis of infection in infants is particularly difficult, measurement of this protein could make a useful contribution, however previous reference values for infants were unsatisfactory.

A solid phase enzyme immunoassay for plasma lactoferrin which required only a small specimen of blood was established. It was linear up to 800 μg/L, with a recovery of between 96 and 99%, and had a between batch precision of between 10 and 15%. Using this method we have determined the level of circulating lactoferrin in term infants during the first three weeks of life to be (mean ± SD) 385 ± 113 μg/L which is significantly (P < 0·005) higher than that found in adults (venous plasma 122± 40 μg/ L; capillary plasma 107± 73 Jμg/L). Plasma lactoferrin levels were still significantly higher than those in adults at weeks 7 and 11 (267 ± 176 μg/L and 269±163 μg/L respectively) but not at week 15 (176± 165 μg/L). There were no differences between infants fed breastmilk and those fed on infant formulas. These findings are discussed in terms of the possible origin and role of lactoferrin in the newborn.
Plasma Lactoferrin Levels in Newborn Preterm Infants: Effect of Infection
Authors: Scott P H
Published: February 2014

Plasma lactoferrin was measured within 24h of birth in 23 preterm infants of between 24 and 36 weeks gestation. Lactoferrin concentrations fell with decreasing gestational age whilst the incidence of subsequent infection rose. Sequential measurements on a subgroup of 10 preterm infants showed that even when initial lactoferrin concentrations were within the range for term infants, they fell during the first week. Lactoferrin concentrations in preterm babies may rise transiently, such increases often being associated with clinical signs of infection. A rise in plasma lactoferrin of 200μg/L or more over a period of less than 48 h is suggestive of infection. These findings are discussed in terms of both the possible role oflactoferrin, and the clinical usefulness of the measurement.
Radioimmunoassay of Human Pancreatic Amylase with Monoclonal Antibody
Authors: Fujita Chiyo , Kasai Chihiro , Kosuge Hiromi , Ogata Kenji , Oshima Ichiyo , Shima Kenji
Published: February 2014

A monoclonal antibody (E-21) was obtained that specifically binds to human pancreatic amylase and shows negligible cross-reaction with human salivary amylase. Using this antibody a radioimmunoassay was developed for pancreatic amylase in human serum. The assay was shown to be sensitive (detectable up to 7 mg/L), reproducible, and specific for pancreatic amylase. In normal subjects, the mean concentration of serum pancreatic amylase determined by this method was 36·3 mg/L with a 95% confidence range of 16·5 to 79·2 mg/L. A good correlation was observed between the concentrations of immunoreactive pancreatic amylase (IR-PA) and enzymatic activities in 20 serum samples ( r = 0·97). The concentration of serum IR-PA was below the detectable limit in pancreatectomised patients, and was greatly increased in patients with acute pancreatitis; the latter was accompanied by parallel changes in total enzymic activity. In patients with mumps, the serum IR-PA level was within the normal range whereas the total enzymic activity was elevated.
Unsuitability of the Human Erythrocyte as a Model for in Vivo Sodium Transport Activation by Beta2 Adrenergic Agonists
Authors: Siebers Robert W L , Burgess Carl D , Flatt Amber , Beasley Richard , Crane Julian
Published: February 2014

Administration of the beta2 adrenergic agonists fenoterol, salbutamol and terbutaline to volunteers significantly reduced plasma potassium concentration in a double-blind crossover study. There was no consistent effect of the three active compounds on erythrocyte sodium concentration. Storage of whole blood at 4°C increased erythrocyte sodium concentration by 33% after 2 h; this could explain the differences between this and another study of the effects of beta2 adrenergic agonists on erythrocyte sodium concentration. We conclude that the human erythrocyte is unsuitable as an indirect in vivo model to demonstrate stimulation of cellular sodium potassium transport mediated by beta2 adrenergic agonists.
Effects of Glucose-6-Phosphate Dehydrogenase Deficiency upon Sickle Cell Anaemia
Authors: Al-Ali A K , Ahmed M A M , Al-Idrissi H , Al-Sibai M H , Al-Mutairy A R , Al-Awami M
Published: February 2014

The levels of glycated haemoglobin, fetal haemoglobin and methaemoglobin in 618 Saudi subjects were determined. A statistically significant decrease in the percentage of glycated haemoglobin was observed in all haemoglobinopathic groups studied in comparison to normal controls. However, there was no significant difference in the percentage of glycated haemoglobin in patients with sickle cell anaemia when compared with those sickle cell subjects who were also glucose-6-phosphate dehydrogenase deficient. This suggests that there is little survival advantage or disadvantage in the combination of glucose-6-phosphate dehydrogenase deficiency and sickle cell anaemia.
Variation in Plasma Apolipoprotein A-1 and B Concentrations following Myocardial Infarction
Authors: Shephard M D S , Hester J , Walmsley R N , White G H
Published: February 2014

Measurements of plasma apolipoprotein A-1 and B concentrations are increasingly used for the laboratory assessment of risk of coronary artery disease (CAD). This study of 22 patients investigated the response of plasma apolipoprotein A-1 and B levels for up to 20 days following a myocardial infarction. Seven of these patients participated in a clinical trial using the drug Tissue Plasminogen Activator (TPA). We established that, unlike many other plasma proteins, apolipoproteins do not display a classic acute phase response following myocardial infarction, although large variations in plasma apolipoprotein levels were observed in the patients investigated. Our studies also show that the measurement of plasma apolipoproteins A-1 and B to assess future CAD risk in myocardial infarction patients should be deferred for a minimum of at least 14 days post-infarction. No significant difference was observed in the pattern of apolipoprotein response between patients receiving TPA and those not given this drug.
Morphine Increases Plasma Immunoreactive Atrial Natriuretic Peptide Levels in Humans
Authors: Öğütman Ç , Özben T , Şadan G , Trakya A , İsbir M
Published: February 2014

Plasma immunoreactive α-atrial natriuretic peptide (IR α-ANP) levels were determined before, and at 5 and 10 min after bolus intravenous administration of morphine (0·15 or 0·30 mg/kg) in 21 otherwise healthy human subjects who underwent elective surgery. Five min after injection IR α-ANP levels had nearly doubled in response to both doses of morphine. At 10 min, plasma IR α-ANP concentrations were lower than at 5 min in the 0·15 mg/kg group suggesting that IR α-ANP levels peak shortly after morphine administration. Morphine has been widely used in the treatment of acute left ventricular failure and ANP is a recently discovered hormone which possesses unique favourable effects in patients with congestive heart failure when administered exogenously. The combination of these data suggests an important potential role for ANP in the mechanism of action of morphine in the treatment of acute left ventricular failure.
Urinary Aluminium Excretion following Renal Transplantation and the Effect of Pulse Steroid Therapy
Authors: Davenport A , Davison A M , Newton K E , Will E J , Gilest G R , Toothill C
Published: February 2014

Urinary aluminium was measured in 48 patients with primary graft function for 14 days following renal transplantation. The plasma aluminium prior to transplantation was greater in those prescribed aluminium-containing phosphate binders (1·7 ± 0·2 vs 0·6 ± 0·2 μmol/L, P < 0·05) and correlated with the duration of dialysis therapy ( r = 0·42, P < 0·008). After an initial reduction the plasma aluminium returned to pre-transplant values by the fifth day. The 24h urinary aluminium excretion, aluminium clearance and fractional aluminium excretion all increased during the first week to a maximum around the sixth postoperative day, thereafter returning to values obtained during the first postoperative days, suggesting an early ‘wash-out’ of a readily accessible aluminium pool followed by a lower steady state determined by the rate of release of aluminium from tissue stores. For the whole group, aluminium excretion, at this steady state, was five times that of urinary aluminium excretion in normal subjects.

Acute allograft rejection was diagnosed in 25 patients, who were treated with pulsed methyl prednisolone. Apart from improving graft function, no additional effect was observed on aluminium excretion, suggesting that the readily accessible aluminium pool does not come from lysosomal release, but probably from aluminium bound to small molecular weight protein.
Modification to a Commercial Immunoradiometric Assay Permitting Intraoperative Monitoring of Parathyroid Hormone Levels
Authors: Ryan M F , Jones S R , Barnes A D
Published: February 2014

We describe a modification to a commercially available immunoradiometric assay which reduces the turnaround time for parathyroid hormone (PTH) measurement to 1 h and permits intraoperative monitoring during parathyroidectomy. Alterations in PTH concentrations following removal of parathyroid tissue are compared with those of calcium, ionised calcium and phosphate. PTH measurements obtained intraoperatively permit definitive conclusions about the success of the operation within 1 h of sampling, allowing re-exploitation of the gland to take place immediately if necessary
Immunoglobulin—AST Complex
Authors: O'Kane M J , Telford Margaret E , Bell P M
Published: February 2014

A case of AST—IgG complex presenting as an isolated AST elevation is described. Measurement of elevated serum AST activity is dependent upon the inclusion of pyridoxal 5-phosphate in the substrate.
Insulin-Like Growth Factor 1 in Patients with Hypoglycaemia
Authors: Labib M , Teale D , Marks V
Published: February 2014

Plasma insulin-like growth factor 1 (IGF-1) concentrations were measured in a group of patients with hypoglycaemia due to endogenous hyperinsulinism, and compared with those in a group of patients matched for age and sex with hypoglycaemia and appropriately suppressed insulin levels. Insulin-like growth factor I concentrations were significantly higher in the hyperinsulinaemic hypoglycaemic group than in either the hypoinsulinaemic hypoglycaemia group or a group of euglycaemic control subjects. These data provide further evidence that insulin promotes IGF-1 production and release from the liver.
Results of a Quality Assurance Exercise for Urinary Glycosaminoglycan Excretion
Authors: Brimble Angela , Pennock Charles , Stone Janet
Published: February 2014

Urine samples collected from four patients with a mucopolysaccharide storage disease (MPS) and two non-MPS patients were distributed to up to 33 laboratories as a test of their ability to detect abnormal glycosaminoglycan excretion. Seven national reference laboratories made a correct diagnostic assignment to all samples analysed. Qualitative turbidity and spot tests were shown to be unreliable. Failure to identify the excretion pattern occurred when reliance was placed on one-dimensional electrophoresis or thin layer chromatography as the sole method for glycosaminoglycan identification. Two-dimensional electrophoresis appeared to be the method of choice provided that staff had adequate experience in interpretation. Clinically unacceptable delays in analysis were common, with 80% of laboratories taking longer than 10 days to issue a report.
A Theoretical Study of Carryover in Selective Access Analysers
Authors: Dixon K
Published: February 2014

Carryover in selective access analysers is of two types: physical (specimen) and chemical (reagent) carryover. There are four constants describing carryover of each analysis: s, the batch carryover constant; k, the interaction constant; m, the slope constant for reagent carryover; and C, the intercept constant for reagent carryover. Procedures to measure these constants are described, and equations to allow correction of results for specimen and reagent carryovers in computer supported instruments are developed.
Syringe Injection Pressure: A Neglected Factor in Blood Po2 Determination
Authors: Gosling P , Dickson G
Published: February 2014

The mean arterial blood Po2 values of 20 patients' samples taken into Sarstedt 2 mL Monovette™ syringes were found to be initially 0·43 kPa higher and after 15 min storage 0–93 kPa higher than the mean values using Corning 3 mL Blood Gas Kit™ syringes. The Sarstedt syringe allowed entry of small air bubbles and the plunger was noted to be stiff. We speculated that high injection pressures might increase measured Po2

Using each type of syringe, 20 ITU staff injected saline into a Corning 178 pH/blood analyser linked to a pressure transducer via a three-way connector. Mean injection pressures for Sarstedt and Corning syringes were 17·15 and 6·42 kPa, respectively ( P < 0·005). Following injection at pressures between 2·8 and 26·6 kPa, the mean Po2 of equilibrated saline containing an air bubble was 0·80 kPa higher than the mean value obtained at injection pressures of < 2·8 kPa. However, with no air bubble the mean Po2 of equilibrated saline was still 0·45 kPa higher when injected at pressures between 2·8 and 26·6 kPa than the mean value obtained with injection pressures of 2·8 kPa. We suggest that for optimal Po2 determinations syringes should not only allow minimal air contamination but also have plungers that reduce injection pressure to a minimum.
Interference by Haemoglobin with the Cresolphthalein Complexone Method for Serum Calcium Measurement
Authors: Corns Cathryn M
Published: February 2014

The spectral interference caused by haemoglobin in the calcium-cresolphthalein complexone reaction was investigated. The results show that the nature of the haemoglobin derivative in the reaction mixture influences the degree of interference; in turn, the derivative formed depends on the order in which the sample and reagents are added. Methods using a single, alkaline cresolphthalein complexone reagent are most seriously affected by haemolysis due to persistence of oxyhaemoglobin. If the sample is added to an acid cresolphthalein complexone reagent then acid haematin is formed, this being converted to a different derivative on the addition of alkali, producing less pronounced interference. The addition of the sample to a buffer, followed by addition of complexone, appears to offer a means to correct for moderate haemolysis in the sample.
Cerebrospinal Fluid Oligoclonal IgM in Multiple Sclerosis: Analytical Problems and Clinical Limitations
Authors: Giles P D , Wroe S J
Published: February 2014

A method for detecting cerebrospinal fluid (CSF) oligoclonal IgM is described. Concentrated CSF was separated by agarose isoelectric-focusing and blotted with poly(vinyldifluoride). A double-antibody immunoperoxidase technique with avidin-biotin amplification was used to stain IgM. Special conditions were required to avoid cross-reaction with IgG.

The method was applied to 99 patients on whom oligoclonal IgG analysis was performed. Positive IgM results occurred in 17 of the 27 patients positive for oligoclonal IgG, and in two patients negative for oligoclonal IgG, neither of whom had multiple sclerosis (MS). Fifteen of the patients positive for oligoclonal IgM had some IgM bands in their sera. Oligoclonal IgM was not found in the CSF of suspected MS patients without oligoclonal IgG, but occurred in several patients with oligoclonal IgG due to other diseases. ***As a test for MS, oligoclonal IgM was less sensitive than oligoclonal IgG and did not improve specificity.
Ultrasensitive Time-Resolved Immunofluorometry of Human Albumin in Urine Using Monoclonal Antibodies—A New Assay for Microalbuminuria
Authors: Diamandis Eleftherios P , Ogilvie Raymond R
Published: February 2014

We describe a two-site, sandwich methodology for human albumin in urine. In the assay, albumin binds to a solid-phase monoclonal antibody and to another monoclonal that is biotinylated. The immunocomplex is then quantified by adding streptavidin which is labelled with an europium chelator, using time-resolved fluorometry. The assay is extremely sensitive (< 1 µg/L) and specific. A sample predilution of 251-fold or more is needed before analysis. The analytical parameters studied (precision, recovery, linearity, comparisons) were found to be satisfactory. The assay is simple to perform and is proposed as a non-isotopic alternative to radioimmunoassay for the quantification of small amounts of albumin in urine for the purpose of assessing microalbuminuria.
The Development of Computer Programs to Predict and Minimise the Effect of Sample Pyruvate on Aspartate Aminotransferase Assays
Authors: Davidson D F
Published: February 2014

Some NADH-linked aspartate aminotransferase (AST) assay systems may produce significant errors due to endogenous pyruvate because the pre-incubation time employed is too short and/or because the reagent lactate dehydrogenase (LD) activity is inadequate. Such errors in patient specimens may go unnoticed if quality control materials themselves contain a low pyruvate concentration.

A theory of pyruvate interference in AST assay is formulated and calculation programs are described which will allow a laboratory to assess whether their particular AST methods are likely to be subject to such interference and also to predict a way of removing any error thus identified.
Measurement of Conjugated Diene Lipids by Derivative Spectroscopy in Heptane Extracts of Plasma
Authors: Situnayake R D , Crump B J , Zezulka A V , Davis M , McConkey B , Thurnham D I
Published: February 2014

A series of experiments are described which show that second derivative spectroscopy can be used to quantify conjugated lipid dienes as markers of lipid peroxidation in heptane extracts of plasma from patients with rheumatoid arthritis, osteoarthritis, and healthy controls. Results obtained by this method gave reasonable agreement with those derived from the measurement of simple absorbance in chloroform/methanol extracts.

Two minima were observed in the derivative spectrum of plasma lipid extracts. These minima occurred at 233 and 241 nm and corresponded to absorbance maxima in the conventional UV spectrum. Using a combination of phospholipase hydrolysis, reverse phase high performance liquid chromatography (HPLC) and second derivative spectroscopy we confirmed that these two minima can be attributed to a single fatty acid (9 cis-, 11 trans-linoleic acid) shown previously to account for greater than 90% of diene conjugation in human plasma samples. When the biological isomer 9 cis-, 11 trans-linoleic acid was separated by reverse phase HPLC from the mixture of other plasma phospholipid-2-esterified fatty acids we observed a change in derivative spectroscopy minima from 233 and 241 nm to 228 and 237 nm. Minima at the latter two wavelengths were also seen with pure preparations of the Paint Research Isomer (9 trans-, 11 trans-linoleic acid) which eluted later than biological 9 cis-, 11 trans-linoleic acid using reverse phase HPLC, suggesting that the absorbtion spectra of these pure cis-, trans and trans, trans dienes are similar but can be altered by the presence of other fatty acids in the extract.
Sweat Sodium and Chloride Concentrations—Essential Criteria for the Diagnosis of Cystic Fibrosis in Adults
Authors: Hall S K , Stableforth D E , Green A
Published: February 2014

Criteria for a positive sweat test in children (sweat sodium greater than 60 mmol/L and sweat chloride greater than 70 mmol/L) were investigated in a series of adults aged between 18 and 40 years using the standard Gibson and Cooke technique of pilocarpine iontophoresis. A significant number of non-cystic fibrosis adults had sweat sodium values greater than 60 mmol/L whereas a concentration of chloride greater than 70 mmol/L always discriminated adults with cystic fibrosis from normal adults and those with chest disease not due to cystic fibrosis. In all cases of adult cystic fibrosis the sweat sodium concentration was greater than 80 mmol/L. The Na:CI ratio and sum of Na and Cl provided additional helpful criteria in distinguishing between adults with and without cystic fibrosis.
Plasma and Serum G4 Isoenzyme of Acetylcholinesterase in Patients with Alzheimer-Type Dementia and Vascular Dementia
Authors: Yamamoto Yasumasa , Nakanot Satoshi , Kawashima Shingo , Nakamura Shigenobu , Urakami Katsuya , Kato Tomonobu , Kameyam Masakuni
Published: February 2014

We developed a new assay for plasma or serum G4 acetylcholinesterase (AChE) activity. There was no difference in G4 AChE activity between serum and plasma. Plasma AChE activity in control subjects (8–92 years) was independent of age. Serum G4 AChE activity was significantly increased in patients with vascular dementia (P < 0·01), compared with age-matched control, and significantly decreased in those with probable Alzheimer-type dementia (P < 0·02). The difference between VD and ATD was significant (P < 0·001), and thus the measurement of plasma or serum G4 AChE activity would be helpful in the differential diagnosis of dementia.
Interference by Haemolysis, Icterus and Lipaemia in Assays on the Beckman Synchron CX5 and Methods for Correction
Authors: Randall A G , Garcia-Webb P , Beilby J P
Published: February 2014

As part of an evaluation of a Synchron CX5 analyser (Beckman Instruments Inc, Brea, USA) we examined a range of tests for interference from haemolysis, bilirubin and lipaemia. Tests investigated were urea, creatinine, urate, total protein, albumin, calcium, total bilirubin, alkaline phosphatase (ALP), aspartate transaminase (AST), γ-glutamyl transferase (GGT) and inorganic phosphate. Two types of interferences were found. One type is found on other analysers and represents analytical difficulties with the measurement of that particular analyte. The other type of interference was a consequence of the bichromatic optical system used on the CX-5. This latter group includes haemoglobin interference in the measurement of total protein and inorganic phosphate, and bilirubin interference with the measurement of total protein, glucose and inorganic phosphate. Lipaemia interfered with total protein, total bilirubin, inorganic phosphate, urate and glucose. Alternative and modified methods are proposed to improve the measurement of total protein, glucose, total bilirubin and inorganic phosphate. The use of the modified methods for glucose, inorganic phosphate and total bilirubin are limited, at this time, by an error in the calculation algorithm used by the analyser for two step or triggered chemistries, and to a lesser extent, by a reduction in sample throughput.
Reference Values: Bhattacharya or the Method Proposed by the Ifcc?
Authors: Oosterhuis W P , Modderman Th A , Pronk C
Published: February 2014

The Bhattacharya method was used to calculate reference values from unselected patient data. These values were compared with reference values obtained from data from a blood donor population group following the recommendations of the IFCC. Differences between the results could be attributed in part to different statistical methods, and in part to differences between populations. With some limitations, the Bhattacharya method can be of help in the determination of reference values and quality control.
The Mathematical Basis of Multivariate Risk Screening: With Special Reference to Screening for Down's Syndrome Associated Pregnancy
Authors: Reynolds T M , Penney M D
Published: February 2014

The underlying mathematical techniques behind the multivariate normal distribution are explained in principle and expanded in detail for up to three variables. The application of multivariate distributions to screening programs is described with particular reference to the calculation of risk ratios for the detection of Down's syndrome between 15 and 19 weeks of gestation.
A Robust Assay for Dexamethasone in Plasma Using a Heterologous 125I Radioligand and a Magnetizable Solid-Phase Antiserum
Authors: Cook N J , Read G F , Lejeune-Lenain C , Riad-Fahmy D
Published: February 2014

An assay using an antiserum raised against a dexamethasone 21-hemisuccinate conjugate and the heterologous radioligand dexamethasone 21-(carboxymethyl) ether was developed, validated, and used to study the pharmacokinetics of this steroid for 12 h following administration to patients with congenital adrenal hyperplasia. Coupling the antiserum to magnetizable cellulose allowed rapid separation of bound/free steroid. A C-21 rather than a C-3 antiserum was used to minimize interference with a main metabolite, 6β-hydroxydexamethasone. Close correspondence of assay (0·35 nmol/L) and curve (0·25 nmol/L) sensitivities suggests that interference by matrix effects is minimal. This was confirmed by good agreement in data from the in-house assay and that of a reference procedure. Good precision was demonstrated by the precision profile and Shewhart chart quality control data. The latter also demonstrated the assay was robust and reliable in routine practice.
Postprandial Effect of a High Fat Meal on Plasma Lipid, Lipoprotein Cholesterol and Apolipoprotein Measurements
Authors: Rifai Nader , Merrill Jeffrey R , Holly Robert G
Published: February 2014

We investigated the effect of a fatty meal on plasma concentrations of lipids, apolipoproteins, and the cholesterol component of lipoproteins. Sixteen nonobese, healthy, asymptomatic males, 22–34 years of age, served as subjects for this study. None smoked, consumed more than two alcoholic drinks per day, or took any medication known to alter plasma lipids. After a 12 h fast, baseline plasma samples were obtained just before subjects consumed a high fat meal. The meal, standardized to a 70 kg individual, contained approximately 70 g fat, 580 mg cholesterol, and 1100 cal, with 56% of the calories coming from fat. During the 8 h following consumption of the meal, subjects rested quietly and consumed no food or beverages except water. Blood specimens were obtained hourly. There was a significant increase in plasma triglyceride (150% from baseline at 3 h, P < 0·0005). Very low density lipoprotein cholesterol (VLDL-C) concentrations increased 150% at 3 h ( P < 0·0005) while low density lipoprotein cholesterol (LDL-C) concentration decreased 37% at 3 h ( P < 0·005) when estimated by Friedewald's formula. No statistically significant differences were observed between fasting total cholesterol, high density lipoprotein cholesterol (HDL-C), HDL2-C, and HDL3-C, apolipoprotein AI (apo AI, AII), and B-100 concentrations and non-fasting samples. We conclude that plasma triglyceride concentration is significantly affected in the post-prandial state. As a result, VLDL-C and LDL-C when assessed by the Friedewald formula are also altered. A minimum of 8 h fasting is required to assess these concentrations accurately in this population. The concentrations of total cholesterol, HDL-C, HDL2-C, HDL3-C, apo AI, apo AII, and apo B-100 can be determined adequately using a non-fasting specimen.
Prolactin and Growth Hormone: Molecular Heterogeneity and Measurement in Serum
Authors: Smith Caroline R , Norman M R
Published: February 2014

The pituitary hormones prolactin and growth hormone are related single-chain polypeptides. Both hormones exist in the circulation in several molecular forms, and this heterogeneity may account for some of the complex and sometimes contradictory actions, in vivo and in vitro, of both hormones. It may also lead to problems with quantitation by immunoassays and discrepancies between the results given by assays using different antibodies. Modified forms of the hormones may have markedly different activity in bioassays from that of the parent hormone, but the clinical significance of this is unclear. In this review we summarize what is known about the molecular heterogeneity of the hormones and briefly discuss the implications for clinical biochemists.
Breast Cancer-Associated Hypercalcaemia: A Reassessment of Renal Calcium and Phosphate Handling
Authors: Gallacher Stephen J , Fraser William D , Patel Uday , Logue Fraser C , Soukop Michael , Boyle Iain T , Ralston Stuart H
Published: February 2014

The mechanisms of hypercalcaemia were assessed in 20 hypercalcaemic patients with breast cancer. Abnormalities suggestive of a PTH-related peptide (PTHrP) mechanism were observed in up to 60% of cases; urinary cyclic adenosine monophosphate (UcAMP) was elevated in nine patients (45%), renal tubular reabsorption of calcium (RTRCa) was elevated in nine (45%) and the renal tubular threshold for phosphate reabsorption (TmPO4) depressed in 12 (60%). While TmPO4 was lower in patients with high UcAMP, there was no consistent relationship between RTRCa and UcAMP or UcAMP and the extent of bone metastases.

In a control group of nine normocalcaemic breast cancer patients, bone resorption as assessed by urinary calcium/creatinine ratio was slightly increased but UcAMP, RTRCa and TmPO4 were generally normal.

These observations indicate that a PTHrP-mediated mechanism of hypercalcaemia may be operative in up to 60% of patients with breast cancer, irrespective of the presence or extent of bone metastases.
Determination of Creatine Kinase in the Sera of Patients with Myocardial Infarction by a ρ-Nitrophenylglyoxal Method
Authors: Aminlari Mahmoud , Rezaian Gholam Reza
Published: February 2014

We have developed a new colorimetric method for the determination of creatine kinase (CK). This method is based on the reaction of creatine, formed enzymatically from creatine phosphate and ADP, with ρ-nitrophenylglyoxal (PNPG) under mild alkaline conditions to produce a coloured complex which absorbs maximally at 480 nm. This method was applied to the sera of patients with myocardial infarction. The results obtained by the PNPG method agreed well with the results obtained by other available methods for CK. However, the PNPG method was more convenient and less expensive than other methods and required a single chromogenic reagent. The PNPG method might be easily adapted to routine clinical application.
Cytochemical Determination of Intracellular Polymorphonuclear Leukocyte Elastase Content in Patients with Severe Bacterial Infection and Septicaemia Correlated with Coagulation Parameters
Authors: Eldanasouri N , Seitz R , Wolf M , Egbring R , Elden A Shams , Havemann K
Published: February 2014

Haemorrhagic disorders are known to occur during septicaemia. We studied the role of elastase-like protease (ELP) of human granulocytes in the activation and consumption of clotting factors and their specific inhibitors. Patients with septicaemia and severe bacterial infection were examined for ELP content in polymorphonuclear leukocytes (PNL), as well as plasma levels of ELP complexed to α-1 protease inhibitor, total α-1 protease inhibitor (α-1 PI), clotting factor VII and partial thromboplastin time (PTT). In all patients, a decrease in ELP content of PNL was accompanied by an increase in plasma ELP complexes. The degree to which ELP content of PNL was lowered was related both to the clinical diagnosis and the course of illness. The ELP content of PNL showed a significant positive correlation with plasma factor VII and significant negative correlations with PTT and α-1 PI. These data suggest that ELP release is accompanied by stimulation of the production of α-1 PI, and may contribute in vivo to the consumption of coagulation factors.

The correlation with PTT might point to an activation of Hageman factor, which may activate both intrinsic coagulation and ELP release. The estimation of ELP content in PNL in patients with septicaemia is likely to represent intravascular ELP release during the inflammatory process. It appears to be useful in combination with the assay of ELP complex in plasma the level of which is influenced by the capacity of the reticuloendothelial system for clearance.
Effect of Heat Inactivation of HIV on Specific Serum Proteins and Tumour Markers
Authors: Gleeson Maree , Herd Lynn , Burns Christine
Published: February 2014

The effect on the concentrations of specific serum proteins and tumour markers, of heat-treating samples at 56°C for 30 min to inactivate HIV, was investigated. Statistically significant decreases, that may affect clinical decisions, were observed for α-1-antitrypsin, β-2-microglobulin, IgE, fibrinogen, C***1-esterase inhibitor and CA125. Statistical, but not clinically significant, changes were observed for α-1-acid glycoprotein, C3, haptoglobin, IgA, IgG, IgM and transferrin. A significant decrease in the α-1 band was observed on protein electrophoresis.
Assessment of Oxygenation in the Critically Ill
Authors: Clapham M C C
Published: February 2014

This paper reviews the physiology and pathology of oxygen transport from the atmosphere to the cells in critically ill patients. A thorough understanding of this allows a rational approach to monitoring and managing an hypoxic patient in the intensive care setting.
The Short-Term Effect of Nicotinic Acid on Intermediary Metabolism in Insulin-Dependent Diabetes Mellitus
Authors: Hale P J , Nattrass M
Published: February 2014

The short-term effect of the lipid lowering agent nicotinic acid on circulating concentrations of insulin, glucose, lactate, pyruvate, non-esterified fatty acids (NEFA), glycerol, total ketone bodies and triglycerides was examined in six insulin-dependent diabetic patients. On two occasions a week apart 24 h metabolic profiles were performed. Three patients received nicotinic acid (800 mg/day) for 1 week prior to the first study and three patients between studies. Using this dose of nicotinic acid in patients with insulin-dependent diabetes no lipid lowering effect was demonstrated, nor did we observe an impairment of glycaemic control. During treatment with nicotinic acid circulating free insulin concentrations were higher and blood glucose concentrations were lower. Despite the higher insulin concentrations, circulating levels of NEFA, ketone bodies, and glycerol were all significantly elevated during treatment with nicotinic acid. These results suggest that any extrapolation of findings with regard to the use of nicotinic acid and its derivatives in non-insulin-dependent diabetes to insulin-dependent diabetes should be considered with caution.
A Semi-Automated Micromethod for the Determination of Calcium and Phosphorus in Human Milk
Authors: Laskey M Ann , Dibba Bakary , Prentice Ann
Published: February 2014

A simple, semi-automated method for the analysis of calcium and phosphorus in small volumes of human milk is described. Samples are ashed, digested with dilute hydrochloric acid and assayed with commercially available kits on a centrifugal analyser. The precision and accuracy of the method are similar to those of standard manual methods using larger volumes of milk. Analysis of human milk for phosphorus without prior ashing and digestion gives observed concentrations only 30–40% of their true value.
Effect of Bilirubin on Uricase-Peroxidase Coupled Reactions. Implications for Urate Measurement in Clinical Samples and External Quality Assessment Schemes
Authors: Hullin D A , McGrane M T G
Published: February 2014

Methods for the determination of serum urate which employ the uricase-peroxidase reaction may suffer interference from concentrations of bilirubin which can be found in relatively mild jaundice. Such concentrations of bilirubin are also frequently present in sera distributed as part of an external quality assessment scheme and, for this reason, laboratories should be particularly careful not to recalibrate their urate assays to attempt to achieve results closer to the consensus mean.