bluuebunny/crossref_metadata_2025 huggingface dataset:
Serum Albumin by Dye-Binding: Bromocresol Green or Bromocresol Purple? The Case for Conservatism
Authors: McGinlay Jean M , Payne R B
Published: February 2014

Pooled patient's serum selected to have a wide range of albumin concentrations was analysed for albumin by bromocresol green with both long and short incubation times and also by bromocresol purple. Total protein, colloid osmotic pressure, calcium and magnesium were also measured. There were strong linear correlations between albumin measured by the three methods. Albumin values by bromocresol green with a short incubation time (1·5 min) averaged 5 g/L higher than those by bromocresol purple at all albumin concentrations. Colloid osmotic pressure correlated less strongly with total protein and with albumin by bromocresol purple than with albumin by the two bromocresol green methods. There were no significant differences between the correlation coefficients of calcium or magnesium with total protein and with albumin measured by the three methods. Bromocresol purple has no advantage over bromocresol green with a short incubation time for the clinical purposes for which albumin is measured: to detect abnormality, monitor change, predict colloid osmotic pressure and adjust calcium and magnesium for abnormal protein concentrations.
A Simple Method for Determination of Plasma Thiocyanate
Authors: Falkensson M , Lundquist P , Rosling H , Söurbo B
Published: February 2014

We describe a method for the determination of thiocyanate in plasma from blood collected under field conditions in heparinised glass capillary tubes. After deproteinisation of plasma with perchloric acid, thiocyanate is directly determined colorimetrically by the König reaction with sodium hypochlorite as the chlorinating reagent and barbituric acid as the coupling agent. This simple method cannot be applied to urine as the latter contains interfering compounds.
Correlates of Diabetes Markers with Erythrocytic Enzymes Decomposing Reactive Oxygen Species
Authors: Tho L L , Candlish J K , Thai A C
Published: February 2014

Superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase were assayed in the erythrocytes of a diabetic population on various treatment regimens (diet, oral therapy, and insulin), to investigate any relationships between their activities and diabetes markers (serum glucose, lipids, and fructosamine, as well as glycated haemoglobin). In the group of patients as a whole, there was significant negative correlation of SOD, but not of the other two enzymes with glycated haemoglobin and fructosamine. Specifically, there was a lower activity of the enzyme in the poorly-controlled patients. It is concluded that SOD in particular is potentially an additional marker for long-term diabetic pathophysiology.
Reference Values for Analytes of 24-H Urine Collections Known to Be Complete
Authors: Bingham Sheila A , Williams RHYS , Cole Timothy J , Price Christopher P , Cummings John H
Published: February 2014

One hundred and twenty two 24-h urine collections were obtained from a representative sample of men and women in the general population aged 25–44 years. The collections were verified for their completeness by urine recovery of oral doses of para-amino benzoic acid. Means (with 0·95 reference intervals) for both sexes for 24-h urinary output were determined for nitrogen, urea, creatinine, urate, ammonia, sodium, potassium, volume, and pH. Within person variation in nitrogen, urea, creatinine, ammonia, sodium and potassium was estimated for a consecutive 28-day series of 24-h urine collections for eight individuals. Within person variation was greatest for sodium and least for creatinine. These differences when compared with the between person variation in the analytes studied have implications for the precision with which a result from a single specimen can be used to place an individual within a distribution of values for epidemiological purposes. In clinical biochemistry, the population results reported here should be appropriate as a reference base for comparison with individual patient results.
Interpretation of Sweat Sodium Results—The Effect of Patient Age
Authors: Kirk J M , Westwood A
Published: February 2014

In a retrospective study of sweat tests performed on 650 patients, sweat sodium was shown to increase with age in children without cystic fibrosis. The clearest separation of children with and without cystic fibrosis was in the youngest infants, while the highest proportion of repeatedly equivocal results was in the older children. Applying age-related reference ranges did not resolve the equivocal cases without also missing some cases of cystic fibrosis.
Erythrocyte and Plasma Magnesium Status in Nigerians with Diabetes Mellitus
Authors: Olukoga A O , Erasmus R T , Adewoye H O
Published: February 2014

Erythrocyte and fasting plasma magnesium were assayed by a dyebinding colorimetric method using the metallochromic dye, Calmagite, in 51 diabetic Nigerians and 25 controls. Erythrocyte magnesium concentrations were similar in the diabetics and the controls. Fasting plasma magnesium concentrations were significantly lower only in insulin-treated diabetics as compared to controls. No significant correlations were observed between fasting plasma glucose concentrations and either plasma or erythrocyte magnesium concentrations in the diabetic groups. Also, no significant correlation was found between erythrocyte magnesium and plasma magnesium concentrations. However, erythrocyte magnesium concentrations were directly related to age while plasma magnesium concentrations were directly related to duration of diabetes in all diabetics. Erythrocyte and plasma magnesium concentrations were not significantly affected by sex and degree of plasma glucose control.

These results suggest that insulin-treated black African diabetics may develop hypomagnesaemia which is not associated with depletion of the erythrocyte content of magnesium.
Plasma Albumin and Haemodilution: The Problem of Interpretation in Sequential Studies
Authors: Taggart D P , Fraser W D , Fell G S , Wheatley D J , Shenkin A
Published: February 2014

The ability of four formulae (3 based on packed cell volume and one on alpha-2 macroglobulin) to correct for postoperative dilutional changes in plasma albumin was assessed in 4 patients undergoing coronary artery surgery. Cardiopulmonary bypass is a stringent test of the efficacy of the formulae to correct for haemodilution as a large volume of fluid is added to the circulation in a relatively short period of time. Plasma albumin was measured 8 times in the perioperative period in the 4 patients and the clinical situation was mimicked in vitro by adding various volumes of diluent to whole blood. None of the formulae consistently corrected for predicted changes in plasma albumin concentration in vivo; two of the formulae corrected for in vitro changes in plasma albumin but the same formulae produced considerable over-correction when applied in vivo. The problem of correcting for perioperative dilutional changes in plasma albumin is discussed.
Simultaneous Assay for Urinary 4-Hydroxy-3-Methoxymandelic Acid, 5-Hydroxyindoleacetic Acid and Homovanillic Acid by Isocratic HPLC with Electrochemical Detection
Authors: Davidson D F
Published: February 2014

A method is described for the simultaneous determination of urinary HMMA, 5-HIAA and HVA by HPLC with electrochemical detection. The method was evaluated over an 8-month period and has thus far identified 2 cases of phaeochromocytoma, 1 case of neuroblastoma and 2 of carcinoid tumour.
An Evaluation of Six Methods for the Detection of Drugs of Abuse in Urine
Authors: Simpson D , Jarvie D R , Heyworth R
Published: February 2014

The detection of drugs of abuse in urine by four commercial immunoassay systems (TDx, BCL and PFI-20 opiates, and PFI-20 morphine) and one commercial TLC system (Toxi-Lab) was investigated and results compared with those obtained by a dual-column capillary GC system. The TDx system was the most reliable method for preliminary screening of urines for opiates; all the commercial immunoassay systems gave some results which were at variance with those of the GC. The GC method proved to be more reliable than the commercial TLC system in discriminating between the different opiates and is recommended for identification of drugs of abuse in urine specimens in which positive results have been obtained with preliminary screening procedures.
Serum Albumin and the Specificity of Free Tri-Iodothyronine as a Test for Hypothyroidism
Authors: Wright D J , Biddulph L , Rinsler M G
Published: February 2014

Serum free tri-iodothyronine (FT3), using two different radioimmunoassays, and serum albumin, using bromocresol green dye-binding method, were measured prospectively in 1374 adults investigated for thyroid disease. The results of similar pairs of measurements in 6608 serum specimens obtained from adults, but using one of the radioimmunoassays for FT3, were examined retrospectively. A close correlation was observed between the FT3 values and serum albumin concentration. Normalisation of the FT3 level using a standard albumin value of 43 g/L in the absence of chemical evidence of hypothyroidism (serum thyrotrophin <6·5 mIU/L) gave a distribution of FT3 values which closely resembled that from a normal population. The effects of acute illness and old age, which may lower the FT3 value, can be corrected by this transformation.
Comparison of Two Latex Agglutination Test Kits for Serum Myoglobin in the Exclusion of Acute Myocardial Infarction
Authors: Konings C H , Küpper A J Funke , Verheugt F W A
Published: February 2014

The Myolex (Orion) and the RapiTex (Behringwerke) latex agglutination tests for the rapid detection of elevated levels of serum myoglobin were studied prospectively in patients suspected of acute myocardial infarction, who were admitted to hospital within 8 h of pain onset. Using admission blood samples drawn 3·4 ± 2·0 h (mean ± SD) after onset of symptoms, the negative predictive values of both tests were too low to use these assays in the early exclusion of myocardial infarction in the emergency department. However, the negative predictive values obtained with the second blood samples, drawn 4 h later, indicated that the myoglobin agglutination test could be of value in the exclusion of myocardial infarction.
Oligoclonal Bands and the IgG Index in Multiple Sclerosis: Uses and Limitations
Authors: Giles P D , Heath J P , Wroe S J
Published: February 2014

The relationship between two tests commonly used in the investigation of multiple sclerosis (MS), the IgG index and oligoclonal bands, has been assessed. Using an immunoblotting technique specific for IgG, analysis of cerebrospinal fluid for oligoclonal bands was found to provide greater diagnostic sensitivity than the IgG index without any loss of specificity. In patients without oligoclonal bands the IgG index had no diagnostic value for MS and in the presence of bands the magnitude of the index was unrelated to the clinical certainty of the diagnosis. High values of the IgGindex were invariably associated with the presence of oligoclonal bands and the IgG index appeared to have no clinical significance independent of this relationship. Even as a screening test the IgG index has serious limitations.
Effect of Body Mass and other Factors on Serum Liver Enzyme Levels in Men Attending for Well Population Screening
Authors: Robinson D , Whitehead T P
Published: February 2014

Alcohol abuse is usually regarded as the most likely cause of elevated serum liver enzyme values in those attending for well population screening, but we have found increased body weight to be an important contributing factor. We have measured serum levels of alanine amino-transferase (ALT), aspartate aminotransferase (AST) and γ-glutamyl transferase (GGT) in approximately 21 000 men attending for routine health screening, and related these to behavioural factors such as alcohol consumption, cigarette smoking, exercise level and obesity.

The levels of all three enzymes were positively correlated with levels of alcohol consumption. Decreasing levels of physical activity were associated with increases in mean ALT and GGT levels. Cigarette smoking showed only a weak effect on ALT and AST, which became non-significant after multivariate statistical analysis, but increasing consumption of cigarettes was associated with increased mean levels of GGT.

In contrast, all three enzymes showed marked increases in mean levels with increasing body mass index (BMI). The effect of obesity was particularly important in the case of ALT: the prevalence of increased ALT values in obese subjects (BMI ≥ 31 kg/m2) was more than eight times that in those with normal weight (BMI ≤ 25 kg/m2), even after allowing for the confounding effect of alcohol consumption.

This study is concerned solely with male subjects, but we hope to extend the analysis to females in the near future.
A Capillary Column Gas-Chromatographic Method for the Identification of Drugs of Abuse in Urine Samples
Authors: Caldwell R , Challenger H
Published: February 2014

This paper describes the application of capillary column gas liquid chromatography (GLC) to the analysis of urine samples for drugs of abuse.

A simple basic extraction into butylacetate is followed by temperature programmed analysis from 90°C to 310°C to provide a comprehensive screen for basic drugs, Retention data are presented for approximately 300 compounds.

The use of capillary column GLC is compared with packed column methods used previously in this laboratory. The reproducibility of retention data and sensitivity of this analysis for several commonly encountered drugs are presented.
Changes in Osteocalcin after Femoral Neck Fracture
Authors: Thompson S P , White D A , Hosking D J , Wilton T J , Pawley E
Published: February 2014

In a group of elderly patients with osteoporosis and femoral neck fracture, osteocalcin concentrations rose significantly in the first week after fracture fixation. The changes in osteocalcin correlated well with the changes in plasma 1,25***-dihydroxycholecalciferol ( P < 0·001).
Advantages of IRMA over RIA in the Measurement of ACTH
Authors: Gibson S , Pollock A , Littley M , Shalet S , White A
Published: February 2014

A technically simple and rapid two-site immunoradiometric assay (IRMA) for human ACTH, based on monoclonal antibodies (MAbs), was compared with a clinically validated ACTH radioimmunoassay (RIA). Both methods measure ACTH 1–39 in unextracted plasma and cross-react <0·5% with ACTH fragments. ACTH levels were assessed in 103 patient samples: for concentrations in the range 5·3–1000 ng/L, results by the two methods were significantly correlated ( r = 0.82, n = 86, P < 0·001). The IRMA was more sensitive and had a wider working range than the RIA (detection limits 5·3 ng/L (IRMA) vs 11 ng/L (RIA); CV < 10% between 19 and 1000 ng/L (IRMA) and CV < 15% between 30 and 400 ng/L (RIA)). In two patients for whom discrepant results were obtained, measurement of ACTH by bioassay and ACTH precursors by direct IRMA demonstrated the greater accuracy of the ACTH IRMA result. The improved performance of the IRMA combined with its many practical advantages compared to RIA, make it ideal for use in detailed clinical and physiological studies which have previously been hampered by the poor reliability of ACTH measurement.
Distribution of Haemoglobin in Patients Presenting to Their General Practitioner, and its Correlation with Serum Ferritin
Authors: Challand G S , Michaeloudis Androulla , Watfa Rodeina R , Coles S J , Macklin J L
Published: February 2014

We have conducted a survey in the United Kingdom in order to evaluate the prevalence of anaemia and of iron deficiency in elderly male and female patients and in female patients of child-bearing age presenting to their general practitioner. Although haemoglobin values were approximately normally distributed, there was evidence of a bimodal distribution of serum ferritin values, particularly in elderly men. A correlation between serum ferritin and haemoglobin values was found to exist, both in the elderly and in younger women.

The overall prevalence of anaemia in the study population was 14·3%, although it was higher for elderly men (20·1%) than either elderly women (13·7%) or women of child-bearing age (11·9%). Iron deficiency associated with anaemia was more common in elderly men (45·2% of those anaemic) than elderly women (28·6%) or women of child-bearing age (25·6%).

This survey indicates that the prevalence of anaemia among certain groups of high risk patients presenting for consultation to their general practitioner is about 1 in 7, although the prevalence is as high as 1 in 5 in elderly men.
Laboratory Investigation of Cerebrospinal Fluid Proteins
Authors: Thompson E J , Keir G
Published: February 2014

Analysis of CSF proteins is useful in the diagnosis and management of neurological diseases in the following situations:

In inflammatory conditions when there is breakdown of blood-CSF barrier integrity. Meningitis is a medical emergency, with CSF total protein measurement being only a screening test. In the detection of immune responses within the CNS. This is by far the most important application in a routine clinical setting, as it is now a firmly established criterion in the diagnosis of multiple sclerosis. Oligoclonal bands restricted to the CSF are the only reliable indicators of intrathecal immunoglobulin G synthesis and are practically always associated with inflammatory disease of the CNS. The method of choice for detecting oligoclonal bands is isoelectric focusing with immunofixation. Quantitative measurement of IgG in the CSF is of no value in diagnostic pathology. In destructive brain diseases when brain-specific proteins are released into the CSF, measurement of these proteins can give prognostic information.
Gas Chromatographic Measurement of Cocaine in Serum, Plasma and Whole Blood
Authors: Dawling Sheila , Essex Edward G , Ward Neil , Widdop Brian
Published: February 2014

A gas chromatographic method is presented to measure cocaine in serum, plasma or blood. To reduce the in-vitro chemical and enzymic hydrolysis of cocaine, samples should be collected into fluoride oxalate tubes, frozen immediately and stored at — 20°C until analysis. Extractions are carried out in disposable glass tubes immersed in an ice-bath. The method uses a single step extraction from a mildly basic solution into n-butyl acetate containing maprotiline internal standard. A portion of the upper organic layer is chromatographed for 5 min isothermally on a packed column (3% SP2250) with nitrogen-phosphorus detection. The coefficient of variation (CV) of the assay is below 6% at 0·1 mg/L and the limit of accurate measurement is 0·02 mg/L. A case of acute cocaine intoxication is described to illustrate the application of the method.
The Role of Magnesium in Clinical Biochemistry: An Overview
Authors: Ryan Michael F
Published: February 2014

Magnesium is the second most abundant intracellular cation. It is essential for a wide variety of metabolically important reactions, in particular those involving ATP. Hypomagnesaemia is surprisingly common in hospital populations but is sometimes either undetected or overlooked.

Serum magnesium concentrations provide a guide to magnesium status but while hypomagnesaemia is a reliable indicator of magnesium deficiency, normomagnesaemia does not exclude magnesium depletion. A wide variety of conditions predispose to magnesium depiction. Clinical magnesium deficiency has potentially fatal consequences in vulnerable groups of patients and should be excluded in all such cases. Magnesium deficiency may result in hypokalemia, hypocalcaemia or other disturbances of electrolyte homeostasis, refractory cardiac arrhythmias, or increased sensitivity to digoxin.

The capacity to measure serum and urine magnesium concentrations rapidly, regularly and reliably should be part of the repertoire of all clinical chemistry laboratories involved in the care of critically ill patients.
Assessment of Theophylline Compliance in General Practice Using a ‘Compliance Index’ Based on Apparent Drug Clearance
Authors: Watson I D , Langan C E , Stewart M J
Published: February 2014

The monitoring of compliance in outpatients using serum drug levels suffers from the difficulty of relating concentrations to changes in dosage. Clearance is independent of dose for most drugs, and may be predicted using a Bayesian based forecasting program. This paper describes how the apparent clearance obtained following a single drug analysis can be compared with the Bayesian population value to derive a Compliance Index. In compliant individuals with stable hepatic and renal function this index should remain constant. We evaluated the usefulness of the Compliance Index in general practice with patients prescribed theophylline. Of 54 patients examined on up to five occasions, only 12% were deemed to be fully compliant at all times. Compliance improved during the study, but worsened again once regular consultation ceased. The results indicate that such a Compliance Index is a viable method of assessing compliance with the aid of concentration measurements.
Multicentre Comparison of the Novo Biolabs Immunometric CK-MB Assay with Four Established Methods
Authors: Wulkan R W , van Loon J , Sturk A , Boerma G J M , Verdegaal M C J M , van den Berg B , Souverijn J H M , Sanders G T B
Published: February 2014

The analytical performance of a new immunometric CK-MB assay from Novo Biolabs was evaluated in three hospitals. Comparisons were made with another immunometric assay, an immune inhibition/precipitation technique, an immune inhibition method, and a column separation method. The Novo assay exhibited good precision (CV 3–7%) at all concentration levels tested (6–150 μg/L) and was found to be linear over the range 0–200 μg/L. Comparison of the Novo kit with the other methods using patients' sera showed acceptable correlation between the methods over a wide concentration range ( r = 0·96–0·99). We conclude that the assay is a useful adjunct to the specific measurement of CK-MB, particularly in routine laboratories with a high throughput of such determinations.
Transferrinuria in Type 2 Diabetes: The Effect of Glycaemic Control
Authors: O'Donnell M J , Watson J , Martin P , Chapman C , Barnett A H
Published: February 2014

Urinary excretion rates of transferrin, albumin, N-acetyl-β-D-glucosaminidase (NAG) and α-1-microglobulin (A1M) were measured in type 2 (non-insulin-dependent) diabetic patients at diagnosis and after 6 and 12 weeks treatment. Initially 21 (53%) patients had elevated transferrin excretion rates. The proportion of patients with raised transferrin excretion rates fell to 30% at 6 weeks and 20% at 12 weeks with treatment of diabetes. At diagnosis 11 (28%) patients had elevated albumin excretion rates and 10 of these had elevated transferrin excretion rates. After 6 weeks treatment only six (15%) had elevated albumin excretion rates and by 12 weeks this number had fallen to four (10%). NAG and A1M levels also fell with treatment of diabetes. There were correlations between the transferrin excretion rate and albumin excretion rate ( r = 0·86, P < 0·0001), transferrin excretion rate and NAG ( r = 0·46, P < 0·0001), and transferrin excretion rate and A1M ( r = 0·55, P < 0·0001) at each visit. There were weaker correlations between the albumin excretion rate and A1M and NAG at each visit. The correlations between the transferrin excretion rate and markers of tubular function (NAG and A1M) suggest that tubular dysfunction may play a part in renal loss of transferrin in diabetes mellitus. There were no differences in transferrin excretion rales between patients with and without evidence of complications.
Primary Hyperaldosteronism in England and Wales: A Review of the Use of a Supraregional Assay Service Laboratory for the Measurement of Aldosterone and Plasma Renin Activity
Authors: Short Frances , James V H T
Published: February 2014

To ascertain the use being made of a Supraregional Assay Service laboratory in the diagnosis of primary hyperaldosteronism, follow-up data were obtained on 60 patients in whom the diagnosis was suggested by the biochemical results. In 36 patients an adrenal adenoma had been removed; 14 patients had evidence of an adenoma on CT scan; 10 patients were presumed to have bilateral adrenal hyperplasia. The data used to make the diagnosis of primary hyperaldosteronism and to assess the likelihood of the presence of an adenoma indicate that patients studied at 40 centres in the UK show results very similar to those of North American series where large numbers of patients have been described but all have been studied in the same centre. The majority of patients in our series were treated at the hospital at which the diagnosis was made, thus avoiding referral to a centre distant from the patient's home and indicating that the service was being used as originally intended when the Supraregional Assay Service was set up.
In vitro Evaluation of a Heparinized Blood Sampler for Ionized Calcium Measurement
Authors: Sachs Ch , Rabouine Ph , Chaneac M , Kindermans C , Dechaux M
Published: February 2014

When ionized calcium measurements are needed urgently blood has to be sampled with an anticoagulant to allow rapid specimen processing. Heparinate salts cause a decrease in ionized calcium by binding which is clinically significant when the concentration exceeds 15 IU/mL of whole blood. The use of an anticoagulant in an aqueous state induces ‘solution-dilution’ errors. To avoid these two types of error the use of calcium-titrated sodium heparinate in a dry state has been proposed. However, in this situation the actual calcium concentration could be modified if its value were different from the titration level. This possibility has been studied using a commercially available sampler (Radiometer B-129). When the sampler was used as recommended, errors were non-significant around 1 · 25 mmol/L. There was a + 3% increase for low (0 · 75 mmol/L) values and a −2% decrease for high (2 · 50 mmol/L) values. Incomplete syringe filling increased these errors.
The Effect of Weight Correction on Risk Calculations for Down's Syndrome Screening
Authors: Reynolds T M , Penney M D , Hughes H , John R
Published: February 2014

Recent advances in prenatal screening have led to the possibility that the risk of Down's syndrome associated pregnancy may be assessed by blood tests for maternal serum alphafetoprotein, human chorionic gonadotrophin (and possibly unconjugated oestriol) taken at 15–18 weeks of gestation.

In neural tube defect screening correction of maternal serum alphafetoprotein for maternal weight has been recommended, although the precise method for weight correction is still under debate. We report an assessment of weight correction for maternal serum alphafetoprotein and human chorionic gonadotrophin based on 1408 singleton pregnancies and for unconjugated oestriol based on 197 singleton pregnancies. We demonstrate that weight correction of maternal serum alphafetoprotein and human chorionic gonadotrophin is statistically valid but that correction of unconjugated oestriol is not.
Influence of Sex and Age in the Risk of Urolithiasis—A Biochemical Evaluation in Indian Subjects
Authors: Sarada B , Satyanarayana U
Published: February 2014

Urinary lithogenic promoters and inhibitors were estimated in normal Indian men and women of young and old ages to understand the sex difference in the risk of stone disease. Young men displayed increased phosphate excretion and a higher mean calcium (both lithogenic promoters) and lower excretion of citrate (lithogenic inhibitor) compared to women of the same age indicating that young men are more at risk for calculous disease than women. In the older postmenopausal women, there was increased excretion of calcium and magnesium and a lower mean citrate than in the younger women suggesting that oestrogenic activity during reproductive years appears to offer protection against calculogenesis. This study indicates that sex differences exist in the excretion of lithogenic promoters and inhibitors which partly explain the difference in the incidence of urolithiasis between men and women.
Rapid Enzymatic Method for the Measurement of Mannitol in Urine
Authors: Blood Jane , Ingle A R , Allison N , Davies G R , Hill P G
Published: February 2014

A previously described method for mannitol in urine has been modified and improved. End product inhibition by fructose in the mannitol dehydrogenase method for mannitol has been minimized; the assay is linear over a sample mannitol concentration range of 0–12 mmol/L; no significant interference from other sugars or sugar alcohols could be demonstrated. The method is precise (within-batch CV < 1%), rapid and shows excellent recovery of mannitol in spiked samples. Comparison with gas liquid chromatography shows excellent correlation ( r = 0 · 994) between the two methods.
Development and Validation of a Fluoroimmunoassay for Urinary Normetanephrine
Authors: Gallacher Gerard , Mellor Geoffrey W , Landon John , Sjostrom Lena
Published: February 2014

The development of a separation fluoriommunoassay for urinary normetanephrine is described. Antiserum specific to normetanephrine was coupled, using cyanogen bromide, to magnetizable cellulose; and fluorescein labelled normetanephrine was synthesized from fluoresceinthiocarbamylethylene diamine and a previously described normetanephrine derivative. Using these reagents it was possible to construct a reproducible standard curve, covering a wide range of concentrations, and to accurately measure the concentration of this metabolite in acid-hydrolysed urine samples. Cross-reactivities of structurally similar compounds were low and the fluoroimmunoassay showed good correlation with an established gas-chromatographic assay. The procedure is rapid; it is possible to accurately determine the normetanephrine concentration of urine samples approximately 2 h after hydrolysis, resulting in an overall assay time of approximately 4 h. This is the first report of a non-isotopic immunoassay for normetanephrine.
A Broad Spectrum Immunoassay Using Fluorescence Polarization for the Detection of Amphetamines in Urine
Authors: Turner G J , Colbert D L , Chowdry B Z
Published: February 2014

Rapid immunoassays are widely used to screen for amphetamine abuse. Broad spectrum immunoassays are the most useful for this purpose followed by physicochemical techniques for verification and identification of particular drugs. We describe the production of an antiserum with a broad specificity for the amphetamine group of drugs. The antiserum was produced in a sheep using an immunogen linking amphetamine to keyhole limpet haemocyanin via an N-aminobutyl bridge. This antiserum was used to develop a fluorescence polarization immunoassay for application to urine samples. A limited investigation into the use of saliva as an alternative sample was also performed. The effects of chemical modifications to the basic amphetamine structure on antibody binding are discussed.
Plasma C1 Inhibitor in Malignant Diseases: Functional Activity versus Concentration
Authors: Starčević D , Jelić-Ivanović Z , Kalimanovska V
Published: February 2014

Plasma C1 inhibitor (C1-INH) was determined in 64 patients with different malignant diseases and in 58 healthy persons. C1-INH antigen concentration was measured by radial immunodiffusion (RID), whereas its functional activity was assayed with chromogenic substrate. Within-run and day-to-day precision of both methods were good, with CVs ranging from 3·6 to 5·4%. Plasma C1-INH antigen concentrations were significantly higher in the patients than in healthy controls ( P = 4·0 × 10−3), as were their C1-INH functional activities ( P = 3·5 × 10−3). C1-INH activities obtained in the patient plasma samples were in correlation with their antigen concentrations ( r = 0·914), showing that C1-INH synthesized in malignant disease was functional. However, the specific activity of the C1-INH (functional activity/antigen concentration ratio) was significantly lower in the patient group as compared with the controls ( P = 2·1 × 10−6), indicating partial inactivation of plasma C1-INH in malignant diseases. The C1-INH specific activity in patients was inversely proportional to its antigen concentration.
Pulse Polarographic Trace Determination of Bismuth in Natural Waters and Biological Materials
Authors: Namdeo Rajendra P , Pitre K S
Published: February 2014

A convenient and accurate analytical procedure has been developed for the trace determination of bismuth(III) in natural waters and biological fluids. Bismuth gives a well-defined, diffusion-controlled cathodic wave in 1 M HCl with a half wave potential of −0·21 V with reference to a saturated calomel electrode. Trace amounts of Bi(III) have been determined by normal pulse and differential pulse polarographic techniques in a 1 M HCl supporting electrolyte with linear calibration plots. The determination of Bi(III) has been achieved in the presence of metals with which it is commonly associated. This is illustrated with bismuth measurements in the presence of copper and zinc. Suitable methods of preparing the samples for analysis have also been suggested. The method may also be used for the determination of Bi(III) in different natural water samples and biological materials such as blood and urine samples with lowest detection limit of 0·02 μg/L.
Insulin-Like Growth Factor 1: A Valid Nutritional Indicator during Parenteral Feeding of Patients Suffering an Acute Phase Response
Authors: Burgess E J
Published: February 2014

Insulin-like growth factor 1 (IGF-1) is regulated by nutritional intake independently of growth hormone and may be a better nutritional indicator than the plasma proteins. This possibility was investigated in six malnourished inpatients, who suffered sepsis, surgical trauma, or both and who received total parenteral nutrition (TPN) for 10−35 days. Both plasma IGF-1 and pre-albumin showed ( P < 0·05) increases during TPN from baseline values of 0·042−0·42 U/mL (median, 0·11) and 59−156 mg/L (median, 108), respectively, to maxima of 0·19–1·12 U/mL (median, 0·63) and 140–363 mg/L (median, 203). Statistically significant ( P < 0·05) positive correlation occurred between nitrogen balance (range, −7·5 to + 11·0 g/day) and IGF-1 or pre-albumin. Correlation between nitrogen balance and IGF-1 is preserved during the acute phase response to tissue injury when C-reactive protein (CRP) varies in the range 40–248 mg/L. Under these circumstances, the correlation between nitrogen balance and pre-albumin is, in contrast, abolished. These results suggest that IGF-1 behaves as a valid index of nutritional adequacy during parenteral feeding whereas pre-albumin reflects mainly the acute phase response.
Triglyceride Fatty Acid Chain Length Influences the Post Prandial Rise in Serum Intestinal Alkaline Phosphatase Activity
Authors: Day A P , Feher M D , Chopra R , Mayne P D
Published: February 2014

Intestinal alkaline phosphatase (IALP) activity rises following the ingestion of a fat-containing meal. Previous studies on intestinal fluid and lymph have shown that the magnitude of this response is dependent upon fatty acid chain length. To examine this relation in the serum of healthy humans, 10 subjects consumed two standardized fat meals. One meal contained predominantly long chain fatty acid triglycerides, the other contained predominantly medium chain fatty acid triglycerides. Serum IALP activity was measured in serial blood samples using a sensitive immunological assay.

IALP activity was ABO blood group and secretor status dependent. The post-prandial rise in serum IALP activity was significantly greater following the long chain fatty acid meal than following the medium chain fatty acid meal. Previous observations of the fatty acid chain length dependency of the IALP response to fat ingestion, therefore, also apply in the serum of healthy humans under normal physiological conditions. Standardized fat meals provide the basis of a useful method for the investigation of the role of IALP in fat absorption.
Assay of N-Acetyl-β-D-Glucosaminidase in Urine from Neonates: Comparison of Two New Colorimetric Methods Using MNP-GlcNAc and VRA-GlcNAc as Substrates
Authors: Pócsi István , Csáthy László , Oláh V Anna , Price Robert G
Published: February 2014

The NAG activity present in urine from newborn babies was assayed using two colorimetric procedures with either MNP-GlcNAc or VRA-GlcNAc as substrate and compared with data obtained with the well established PNP-GlcNAc procedure. Both new assays were easy to perform and reproducible. The MNP-GlcNAc method has the advantage that it is now available as a kit; however, the VRA-GlcNAc procedure is more sensitive. NAG activity, creatinine concentration and NAG-index values were determined in normal neonates and within-run imprecision calculated. Excellent correlations were found between MNP-GlcNAc-ase and VRA-GlcNAc-ase indices ( r = 0·984) and between PNP-GlcNAc-ase and VRA-GlcNAc-ase indices ( r = 0.952). When low molecular weight urinary components were removed by gel filtration no significant change in VRA-GlcNAc-ase activity was observed.
Maturation of Mitochondrial and other Isoenzymes of Creatine Kinase in Skeletal Muscle of Preterm Born Infants
Authors: Smeitink J , Ruitenbeek W , Lith T v , Sengers R , Trijbels F , Wevers R , Sperl W , de Graaf R
Published: February 2014

We studied pre- and postnatal changes in total creatine kinase (CK) activity, mitochondrial creatine kinase (Mi-CK) activity and immunochemical reactivity with anti-Mi-CK antibodies in skeletal muscle specimens from 12 infants, 10 of them preterm born, after a pregnancy varying between 28 and 40 weeks. Our results demonstrate that Mi-CK is present in fetal human quadriceps muscle and that the specific activity of Mi-CK increases during prenatal development from week 28 to 40 by a factor about two. Generally, adult levels have not been reached at birth, indicating a further postnatal increase of the activity of the enzyme. The Mi-CK protein content also increases during prenatal development. These results suggest that in human skeletal muscle the expression and accumulation of Mi-CK starts at mid-gestation, later than is known to occur for cytosolic CK.
Glycated Haemoglobin: An Assessment of High Capacity Liquid Chromatographic and Immunoassay Methods
Authors: Standing Susan J , Taylor Richard P
Published: February 2014

We have assessed five high-throughput systems for the measurement of glycated haemoglobin and have reviewed published evaluations of individual analysers. All systems offered better precision than a widely used electroendosmosis method. The low pressure chromatography and immunoassay systems demonstrated greater between-batch imprecision than the high performance liquid chromatography analysers, the latter achieving the proposed analytical goal of between-batch coefficients of variation less than 5%. Agreement between all systems measuring HbA1 was good but there was variability amongst observed HbA1c values. The systems were also assessed for their quality of chromatographic separation, simplicity of operation, flexibility, cost and potential for interference by other haemoglobins.
Free Beta Human Choriogonadotropin in Down's Syndrome Screening: A Multicentre Study of its Role Compared with other Biochemical Markers
Authors: Spencer Kevin , Coombes Ed J , Mallard Angela S , Ward A Milford
Published: February 2014

To ascertain the value of maternal serum free β-human choriogonadotropin subunit measurement in Down's syndrome screening and to compare its effectiveness when screening with a variety of biochemical markers, we have evaluated maternal serum free β-human choriogonadotropin, total human choriogonadotropin, α-fetoprotein and unconjugated oestriol in a large multicentre study of over 2800 unaffected cases and 90 affected cases, the largest collection of Down's cases ever reported.

Of all the markers identified to date, free β-human choriogonadotropin is the marker of choice for use in Down's syndrome screening. When used in early gestation (14–16 weeks) in combination with α-fetoprotein and maternal age, it will allow the detection of 77% of Down's cases. A side-by-side comparison with the performance of total human choriogonadotropin shows the superior detection efficiency of free β-human choriogonadotropin. Unconjugated oestriol adds nothing further to the detection rate compared with the use of α-fetoprotein and free β-human choriogonadotropin alone, and its use results in a 1% increase in false positive rate. We conclude that unconjugated oestriol has no value in Down's screening.

The superior detection rate obtained using free β-human choriogonadotropin is a result of superior detection of Down's cases in women under 30 years old, where the free β-human choriogonadotropin combination detects 100% more cases than does the total human choriogonadotropin combination.
Protein Measurement of Particulate and Solubilized Ovine Liver Membranes
Authors: Hatzoglou Anastassia , Prekezes John , Tsami Marie , Castanas Elias
Published: February 2014

Protein concentration measurements are critical in biochemical work with cellular membranes, including the determination of cell surface receptor concentration in human malignant tissues obtained at surgery or after biopsy. In this study we compared the results of protein concentration measurements in ovine liver cellular membranes using either particulate preparations or membranes solubilized with four different detergents. In all cases protein was determined by two different indirect methods (Lowry's Folin phenol method and Bradford's Coomassie Brilliant Blue dye binding method) and compared to the direct biuret method. Our results indicate that the direct biuret method gives the highest protein concentrations followed by the method of Lowry. Maximal concentrations (approaching those obtained by the direct biuret method) were obtained after membrane solubilization with Triton X-100 (3–5%). It is suggested that either the direct biuret method (whenever protein concentrations permit it) or the method of Lowry after solubilization of membranes with Triton X-100 (3–5%) should be used preferentially for the determination of membrane protein samples.
Mononuclear Blood Cell Magnesium in Older Subjects: Evaluation of its Use in Clinical Practice
Authors: Martin B J , Lyon T D B , Walker W , Fell G S
Published: February 2014

Serum and mononuclear blood cell (MBC) magnesium were measured in 24 healthy community subjects, average age 76 years (67–93), and in 21 ill hospitalized subjects, average age 79 years (65–90). MBC magnesium, expressed asμmol/mg protein, was significantly lower in the in-patient group ( P<0·001), but tended to be higher in the same group when expressed as fmol/cell (not significant). Further samples from community subjects on the same day, and again at 7 days, revealed coefficients of variation for intrasubject analysis of 12% and 22%, respectively (fmol/cell). The equivalent intrasubject values for serum were 2·8% on the same day and 4% at 1 week. MBC magnesium values for inpatients were probably distorted by changes in cell size and cell protein content caused by illness. Biological variability and the effects of illness on the composition and size of cells seem to limit the usefulness of MBC magnesium measurement as a clinical tool for assessment of body magnesium status.
Free β-Chorionic Gonadotropin: A Cross-Reactivity Study of Two Immunometric Assays Used in Prenatal Maternal Serum Screening for Down's Syndrome
Authors: Macri James N , Spencer Kevin , Anderson Robert W , Cook Edward J
Published: February 2014

We have evaluated the cross-reactivity characteristics of two distinct immunometric assays for the measurement of free β-human chorionic gonadotropin (free β). These maternal serum assays have been used in the initial studies which evaluated free β as a marker in the prenatal detection of Down's syndrome. It has been suggested that free β assays are subject to substantial potential for cross-reactivity. To confirm that free β was the analyte responsible for enhanced detection efficiency both non-competitive and competitive cross-reactivity evaluations were undertaken. These studies demonstrated acceptably small cross-reactivity to other glycoprotein hormones or their β components. We conclude that properly designed free β assays will provide specific analyte measurement and improved detection efficiency in Down's syndrome screening.
Predicting the Probability of Helper T Cell Immunodominant Sites through Discriminant Analysis
Authors: Mallios Ronna R
Published: February 2014

Bayesian discriminant analysis is used to predict whether or not a given protein segment will activate helper T cells. The predictor variables are drawn from the products of frequencies of amino acid residues. The model's predictive validity compares favourably with that of alternative modelling strategies, suggesting that this approach merits further investigation.
Audit of Automated Requesting of Serum Magnesium Measurement in Patients with Hypocalcaemia
Authors: Masters P W
Published: February 2014

Laboratory computer records for 71 consecutive hypocalcaemic patients (albumin-adjusted calcium < 2 · 00 mmol/L) without chronic renal failure revealed that 50 (70%) did not have serum magnesium measured. A second review of computer records was carried out 6 months after the initiation of an automated requesting program. This identified 14 patients with hypomagnesaemia (serum magnesium < 0·70 mmol/L) who may otherwise have been undiagnosed. The direct cost to the laboratory was an additional 19 magnesium analyses per month.

It is concluded that hypomagnesaemia is commonly associated with hypocalcaemia but is under-diagnosed. Automated requesting of serum magnesium measurement is a cost-effective way of identifying these patients. However, the fact that only half of these patients had follow-up magnesium requests suggests that there may be a need for further education of clinicians in the significance of hypomagnesaemia.
A Survey of Diagnoses in Patients with a Low Intact Parathyroid Hormone Concentration
Authors: Manning E M C , Fraser W D
Published: February 2014

Intact parathyroid hormone (PTH) was analysed in 1107 samples over a 13 month period. Of these, 181 samples (16%) gave results of ≤ 1 pmol/L and the case notes of 169 of these 181 patients were examined.

Eighty-two patients (48%) were hypercalcaemic at the time of the PTH assay. As expected, the most common diagnosis in this group was hypercalcaemia of malignancy but surprisingly this accounted for only 42 of the hypercalcaemic patients; an unexpectedly high proportion (20 patients) had chronic renal failure with hypercalcaemia due to excessive treatment with 1α-hydroxycholecalciferol; eight patients had transient unexplained hypercalcaemia and the remaining 12 patients were hypercalcaemic for a variety of causes including immobilization, bendrofluazide treatment and Paget's disease.

Fifty-nine patients (35%) were normocalcaemic: 26 had osteoporosis, 10 had chronic renal failure and the remainder had a wide range of diagnoses. It is possible that the low intact PTH result in a proportion of the normocalcaemic group was caused by ingestion of calcium tablets prior to blood sampling for PTH.

Twenty-eight patients (17%) were hypocalcaemic: 24 of these had hypoparathyroidism, two had chronic renal failure and two had transient unexplained hypocalcaemia.
A Rapid Enzyme-Linked Immunosorbent Assay for Serum Amyloid a Using Sequence-Specific Antibodies
Authors: Časl Martin-Tino , Grubb Anders
Published: February 2014

A microtitre plate based enzyme-linked immunosorbent assay for determining the concentration of serum amyloid A (SAA) is described. The method employs easily produced sequence-specific rabbit antibodies and the preferential absorption of SAA to polystyrene, which obviates the use of capture antibodies and allows an assay time of only 3 · 5 h, so that the diagnostic potential of the SAA level as a rapid and reliable marker for inflammation can be fully exploited. The assay has a working concentration range of 0·1–2500 mg/L, which embraces the known biological variation of the SAA concentration. The intra-assay coefficient of variation (CV) for SAA concentrations above 10 mg/L is between 1 · 6 and 3·3% and the inter-assay CV between 3·0 and 4·2%. Recovery of SAA added to serum is from 96 to 102%.