bluuebunny/crossref_metadata_2025 huggingface dataset:
Theophylline Assay on Kodak Ektachem DTSC—Performance and Interference by Structurally-Related Compounds and Salicylate
Authors: Ayers G J , Baldwin A J , Fowler A M , Goudie J H , Burnett D
Published: February 2014

Theophylline was measured with a Kodak Ektachem DTSC using its property of uncompetitive inhibition of alkaline phosphatase. Within- and between-batch reproducibility was satisfactory. Agreement with consensus mean values on quality assessment samples was good as was agreement on patients' samples with a high performance liquid chromatography reference method and an automated fluorescence polarisation immunoassay. At therapeutic theophylline concentrations, no interference was seen with caffeine, theobromine, 1,7-dimethylxanthine, 1,3-dimethyluric acid or 3-propylxanthine. 3-methylxanthine (a theophylline metabolite) gave a positive bias but the concentrations of this metabolite found in serum are such that the clinical significance of this finding is questionable. Salicylate at concentrations which might be found during therapy for paediatric rheumatoid arthritis also gave a positive bias.
Essential Data Derived from Biological Variation for Establishment and Use of Lipid Analyses
Authors: Ford Robert P
Published: February 2014

The analytical and biological components of variation of total cholesterol, high density lipoprotein (HDL) cholesterol, HDL3 cholesterol, HDL2 cholesterol and apolipoproteins A-I and B in serum were assessed in 12 apparently healthy individuals. All analytes showed marked individuality and therefore conventional population based reference intervals are of little use. The differences required for serial results to have changed significantly for these assays were calculated. The data presented confirm that the assays studied have limited value in screening the general population.
Relative Diagnostic Value of Serum Non-SHBG-Bound Testosterone, Free Androgen Index and Free Testosterone in the Assessment of Mild to Moderate Hirsutism
Authors: Blight Lesley F , Judd Stephen J , White Graham H
Published: February 2014

Recent evidence suggests that steroid hormone loosely bound to albumin is available for target-cell entry. Preliminary studies have suggested that a measure of this fraction, non-sex-hormone-binding globulin-bound testosterone (NSB-T), provides the best in vitro diagnostic test for idiopathic hirsutism. We compared the diagnostic value of NSB-T, total testosterone (T), free testosterone (fT), and the free androgen index (FAI) in supporting the clinical diagnosis in 22 pre-menopausal women with hirsutism. NSB-T supported the diagnosis in 50% of cases, compared with 23% for T, 55% for fT by analogue RIA, and 68% for FAI. We conclude that in mild to moderate hirsutism the measurement of NSB-T does not yield diagnostic information additional to that provided by the FAI.
Glycated Haemoglobin and other Biochemical Parameters in Sudanese Diabetics
Authors: Atabani G S , Saeed B O , El Mahdi E M-A , Adam M E , Hassan D A
Published: February 2014

Fasting levels of glycated haemoglobin, cholesterol and triglycerides were studied in 44 patients with non-insulin-dependent diabetes mellitus (NIDDM), 31 patients with insulin-dependent diabetes mellitus (IDDM) and 28 healthy Sudanese individuals. Results confirmed previous observations showing correlation of glycated haemoglobin with fasting blood glucose in NIDDM ( r=0·634; P < 0·001), and with cholesterol in IDDM ( r=0·355; P < 0·05). No correlation of glycated haemoglobin with triglycerides was observed in either group of diabetics. A negative correlation was demonstrated between glycated haemoglobin and the duration of diabetes ( r= −0·552; P < 0·01) in IDDM. It seemed that control improved in these patients as their diabetes progressed, probably through self-education.
Antibody Interference in a Two-Site Immunometnc Assay for Thyrotrophin
Authors: John Rhys , Henley Robert , Barron Nicola
Published: February 2014

Of 1585 consecutive serum samples referred for thyroid function testing, 14 gave erroneously high values from a two-site immunoenzymometric assay for thyrotrophin. The addition of mouse or newborn calf serum to the assay failed to correct the interference. In serum samples from 11 patients who were available for follow up a higher concentration of mouse, but not of horse, sheep or rabbit scrum reduced the interference. The interference was associated only with assay systems which employed horseradish peroxidase but not 125I as a label. Addition of mouse serum and anti-IgM to the assay reagents successfully removed the interference.
Development of an Assay for Human Growth Hormone in Urine Using Commercially Available Reagents
Authors: Evans A J , Wood P J
Published: February 2014

An assay for the measurement of human growth hormone in urine (u-HGH) has been developed using commercially available reagents and its analytical variables have been investigated. The procedure is sensitive to 0·50 μU/L urine, has an interassay precision of 6·2–7·5 (CV%) over the standard curve, and shows good parallelism and recovery. Urine samples for the assay can be collected in plain plastic bottles, stored at room temperature for up to 24 h and, after adding preservative, at −20°C before assay for three months. There was a good correlation between the responses of HGH in serum and in urine during clonidine and insulin stimulation tests.
Comparison of Some Recent Methods for the Differentiation of Elevated Serum Amylase and the Detection of Macroamylasaemia
Authors: Van Deun Armand , Cobbaert Christa , Van Orshoven Angeline , Claeys Georges , Lissens Willy
Published: February 2014

A pancreatic isoamylase method (Pancreatic Alpha-Amylase EPS, Boehringer) that uses monoclonal antibodies showed almost complete immunoinhibition of salivary (S) amylase activity with only a minor decrease of pancreatic (P) amylase activity. The method displayed good sensitivity and linearity. The correlations of P-amylase activities determined by this technique with a wheat-germ inhibition method and with agarose electrophoresis followed by densitometric scanning were excellent. However, both the wheat-germ and monoclonal inhibition methods failed to detect macroamylasaemia. To recognise macroamylases we used the PEG precipitation method and confirmed the results with agarose electrophoresis. Of 161 serum samples with elevated amylase activities, only four out of five with macroamylasaemia were detected by the PEG precipitation method. No false positives were demonstrated. After PEG precipitation of 28 samples, P-amylase determinations were performed on the supernatants. Again, four out of five with macroamylasaemia were recognised.

We consider P-amylase measurement and, when macroamylasaemia is suspected, the combined use of the PEG precipitation method and P-amylase or total amylase determination to be the most practical way to differentiate between elevated serum amylase levels.
A Rapid and Sensitive Immunosorbent Assay for Urinary Albumin
Authors: Van Kamp Gerard J , Van Bezu Jan S M , Mulder Cees
Published: February 2014

We describe a fast, simple and sensitive microliter scale competitive ELISA for the determination of urinary albumin. All reagents are commercially available. In the standard procedure, a minimum concentration of 0·8 mg albumin/L can be measured, although, applying another dilution, 0·04 mg/L can be detected. Within-batch coefficient of variation was 6·9% and 5·6% (at 1:20 and 1:50 dilution, respectively); between-batch variation was 8·6% and 5·6% respectively.

The influence of urine pH and other urine components is minimised in the assay diluting with a casein-containing buffer.
Role of the Standard ‘Liver Function Tests’ in Current Clinical Practice
Authors: Johnson P J
Published: February 2014

A prerequisite of current therapy in liver disease is precise diagnosis. The rapid increase in the number of tests available—immunological, virological, histological and radiological—testifies to this, and reflects the inadequacy of the ‘standard’ liver function tests (LFTs). The LFTs are, however, in contrast to these more sophisticated tests, observer independent and despite their lack of specificity, several characteristic patterns of abnormality can be recognised which direct the physician to the most appropriate definitive investigation. The cheapness and non-invasive nature of the LFTs makes them particularly appropriate for monitoring the course of liver diseases once the diagnosis has been established and this, together with screening for hepatotoxicity of newly developed drugs, is now their main role. A second generation of liver function tests based on the capacity of the liver to eliminate various test compounds may come closer to offering a true estimate of liver function. More accurate methods of measuring the various bilirubin fractions, particularly bilirubin conjugates may also become available in the near future and provide more sensitive tests of liver dysfunction.
Influence of Age, Posture and Intra-Individual Variation on Plasma Levels of Atrial Natriuretic Peptide
Authors: Tan A C I T L , Kloppenborg P W C , Benraad T J
Published: February 2014

This paper describes some factors to which attention should be paid when atrial natriuretic peptide (ANP) values are to be interpreted. Changing from the supine to the sitting position decreased ANP levels, while no further decrease was observed when the upright position was assumed. On the other hand, plasma renin activity (PRA) increased only when changing from the sitting to the upright position. Returning to the supine position decreased PRA, while ANP did not change. Under these conditions plasma aldosterone levels did not differ in any of the four positions. No correlation was observed between the percentage changes of ANP, PRA and aldosterone. ANP values measured in 66 healthy subjects positively correlated with age ( r = 0·59, P < 0·01). To study intra-individual variation, ANP was sampled eight times within one hour. The mean, standard deviation and the coefficient of variation (CV) for each subject were calculated. The CV of 9 out of 15 subjects significantly exceeded the intra-assay coefficient of variation (7·0%), thereby indicating that ANP levels, like those of many other hormones, may exhibit endogenous fluctuations.
Proteinuria Selectivity Index in Saudi Children with Nephrotic Syndrome
Authors: Abdurrahman M B , El Sheikh O K , Elidrissy A T H , Al Kahtani W M , Lambourne A
Published: February 2014

Proteinuria selectivity index (PSI) was determined in 54 Saudi children with nephrotic syndrome whose renal biopsy showed minimal change in 13 and non***-minimal histologic changes in 41 patients. The selectivity was determined with two pairs of proteins, IgG/transferrin and IgG/albumin. There was considerable overlap in the values of PSI in patients with minimal and non-minimal histological changes. The clinical utility of PSI in differentiating minimal change nephrotic syndrome and non-minimal change nephrotic syndrome is low.
Effect of Albumin and Detergent on the Reduction of NBT by 1-Deoxy-1-Morpholinofructose
Authors: Podzorski E , Wells F E
Published: February 2014

The effect of matrix albumin concentration on reduction of NBT by DMF has been investigated together with the effect of cationic additives. Decreased albumin concentration and increased cationic detergent concentration both increased the sensitivity of the assay due to kinetic effects, but addition of a low molecular weight cation had no effect. The reduction of NBT by glycated albumin was not increased in sensitivity by a protein matrix of low concentration. Due to the complexity and poorly understood nature of interaction between DMF and albumin in the reduction of NBT, the authors do not consider DMF to be a suitable primary calibrant for the fructosamine assay.
Analytical and Clinical Evaluation of Three Sensitive Thyrotropin Assays
Authors: Bonte H A , Vermes I , Veer G V D Sluijs
Published: February 2014

Three sensitive assays (Behring, Organon and LKB-Pharmacia) for measurement of serum thyrotropin (TSH) were evaluated. All three assays showed good precision, sensitivity, linearity and for practical purposes negligible high dose hook effects. The correlations between the assays were excellent, but due to standardisation and/or matrix effects there were incomplete recoveries in two kits and the kits showed systematic differences of up to 20% in the TSH values obtained.

The clinical utility of the three assays was investigated in patients with thyroidal and non-thyroidal illnesses and in healthy subjects with thyroxine binding abnormalities.

According to the results of the analytical and clinical evaluation, all three kits are acceptable and reliable as first-line thyroid function tests.
Critical Assessment of the Amerlite Free T4 Assay
Authors: Reilly C P , Adamek K J , Wellby M L
Published: February 2014

The measurement of serum free T4 (FT4) by analogue methods has been severely criticised because the T4 analogue binds to albumin. Amersham have recently introduced a method utilising horseradish peroxidase-labelled-T4 (HRP-T4) designed to overcome this problem and have incorporated it into the Amerlite enhanced luminescence immunoassay system. We have critically evaluated this method for its analytical and clinical validity.

Experiments in which anti-albumin was added to normal serum suggested that the HRP-T4 label did not bind to endogenous albumin while the addition of albumin caused no significant change in FT4 concentration. Adding oleic acid up to 5 mmol/L to simulate increased non-esterified fatty acid concentration did not increase the apparent FT4.

Serum sampled from subjects independently allocated to clinical groups were compared with an euthyroid group. The untreated hyperthyroid group values were distinctly elevated while the untreated hypothyroid group were appropriately low. Oestrogen therapy, low TBG, familial dysalbuminaemic hyperthyroxinaemia and non-thyroidal illness groups all reflected their euthyroid status, as did pregnancy samples which also showed a tendency to lower values in late pregnancy, consistent with previous observations.

In conclusion, the Amerlite FT4 method appears to overcome some of the problems associated with analogue methods. A small survey showed it to be diagnostically valid in a wide variety of clinical states.
Salivary Free Testosterone in Hirsutism
Authors: Osredkar Joško , Vrhovec Ivan , Jesenovec Niko , Kocijančič Andreja , Preželj Janez
Published: February 2014

A sensitive, specific and accurate direct radioimmunoassay of testosterone in human saliva is described. A single salivary testosterone result is shown to be of greater diagnostic use in hirsutism than any of the currently used serum androgen assays. Thus, of 50 hirsute patients, salivary testosterone (Sa-T) was elevated in 34 patients, sex hormone-binding globulin (SHBG) was decreased in 30 women, serum testosterone (S-T) elevated in 13, dehydroepiandrosterone sulphate (DHEA-S) was elevated in 14, and androstenedione in three of the investigated group.
Non-Extraction HPLC Method for the Simultaneous Measurement of Theophylline and Caffeine in Human Serum
Authors: Rainbow Sandra J , Dawson Christine M , Tickner T R
Published: February 2014

A non extraction HPLC method is described for the simultaneous measurement of theophylline and caffeine in human serum using a Pinkerton™ ISRP column and u.v. detection at 275 nm. The method is suitable for therapeutic monitoring of theophylline levels in adults and, in particular, quantitation of both theophylline and caffeine in premature neonates where as little as 10 µL of sample can be used. Comparison of theophylline levels obtained by this method with EMIT analysis show a correlation coefficient of 0·97 ( n = 37) in adults and 0·79 ( n = 16) in premature neonates. There was no correlation between serum theophylline and caffeine levels in premature neonates receiving theophylline therapy. No interference was encountered from endogenous plasma components or other drugs in the 53 patients studied. Precision of the assays compares well with reported values for extraction HPLC and immunochemical analyses.
Investigation of a Persistently Raised Serum AST
Authors: Dawson C M , Connelly M S , Kennedy H J , Howe G D , Tickner T R
Published: February 2014

The AST responsible for a raised enzyme activity, with otherwise normal biochemistry, in a single individual over a 16-month period has been characterized as an IgG (λ)-AST complex by (i) estimation of the molecular size by gel exclusion chromatography on Sephadex G200, (ii) agarose gel electrophoresis, (iii) immunoprecipitation by anti-immunoglobulin antisera and (iv) adsorption on to protein A***-agarose.
Anomalies in pH 7·40 Correction in Ionised Calcium Analysers
Authors: Sachs C , Chaneac M , Rabouine P , Kindermans C , Dechaux M
Published: February 2014

As a preliminary step in a study of the effects of calcium ligands on the pH standardisation of ionised calcium (Ca2+) measurement in blood, the change in Ca2+ induced by Pco2 variation was investigated in 12 serum pools on three different instruments. This type of study should yield a log Ca2+ = f(pH) linear relationship in a pH range around pH 7·40 with a slope characterising the pH-sensitive calcium buffer capacity of the specimen. The pH 7·40 correction line should be horizontal. This was the case for an ICA2 analyser but not for an ICA1 or a Nova 8 analyser. The difference was due to an incorrect setting of the built-in slope correction factor in the ICA2: fortuitously its value was close to the effective slopes of the serum pools used for the test. Thus the anomalous behaviour of the ICA1 and the Nova 8 was due to a discrepancy between the standard built-in algorithm and the characteristics of our serum pools.

These findings led us to question the use of a constant correction factor to normalise actual ionised calcium values.
Purification and Properties of Human Erythrocyte Arginase
Authors: Ikemoto Masaki , Tabata Masayoshi , Murachi Takashi , Totani Masayuki
Published: February 2014

An efficient method for purification of human erythrocyte arginase was developed. This method included two new procedures, hydrophobic chromatography and immunoaffinity chromatography, and yielded 0·7 mg of homogeneous arginase protein from 2·1 L of haemolysate. The molecular weight of native arginase was estimated to be 105 000 by gel filtration on a Sephadex G-150 column, and that of its subunit 35 000 by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. This indicates that the native enzyme is composed of three homologous subunits. Amino acid composition of human erythrocyte arginase was found to be very similar to that of liver arginase of several other mammals. After dialysis against distilled water, the purified arginase still retained its enzymatic activity which was decreased by EDTA and reversibly restored by Mn(II) ion. A specific polyclonal antibody for use in an immunoassay was also produced. This antibody revealed one single band on immunoelectrophoretic analysis of the acetone powder extract, suggesting absence of arginase isoenzymes in human erythrocytes.
Serum Prolactin Bioactivity and Immunoactivity in Hyperprolactinaemic States
Authors: Smith Caroline R , Butler Joan , Hashim Ibrahim , Norman Michael R
Published: February 2014

Serum prolactin concentrations were measured using a sensitive bioassay (Nb2 assay) and by radioimmunoassay in 11 patients with prolactin-secreting pituitary tumours (median serum immunoactive prolactin 5150 mU/L), and in 58 normal control subjects (median prolactin 190 mU/L). The mean ratio of serum prolactin bioactivity to immunoactivity was significantly lower in patients with prolactinomas than in normoprolactinaemic controls. Ten lactating women in the early post-partum period (median prolactin 3800 mU/L), studied as a model of physiological hyperprolactinaemia, also had reduced bioactivity to immunoactivity ratios. Overall, there was a significant negative correlation between bioactivity : immunoactivity ratio and serum immunoactive prolactin.

The change in relative bioactivity of prolactin in serum samples from patients with prolactinomas and in women with physiological hyperprolactinaemia may reflect changes in the molecular heterogeneity of the hormone. Such changes may affect activity in both bioassays and radioimmunoassays.
Colorimetric Glucose Assay Using Thermostable Glucokinase
Authors: Scott D A , Goward C R , Scawen M D , Atkinson T , Price C P
Published: February 2014

A method for assaying glucose in serum or plasma samples using a thermostable glucokinase was developed. Glucokinase from Bacillus Stearothermophilus was coupled with glucose-6-phosphate dehydrogenase to produce NADPH, which reduced the tetrazolium dye MTT to its formazan. Detection of the product at 660 nm allowed samples containing up to 30 mmol/L glucose to be assayed with an endpoint method. Use of the optimal wavelength for formazan detection, 570 nm, increased sensitivity for NADPH detection by over threefold compared to UV detection. The stability of glucokinase assay mixtures was extensively studied, with variation in buffers, salt and enzyme stabilizers. Maximal half life for reagent stability at room temperature was approximately 30 days, with storage of assay mixtures in two solutions. Various drugs and metabolites were tested for interference in the method and no significant interferences were found.
Combined Single Day 14C-Triolein Breath Test and Paba Test in the Diagnosis of Malabsorption
Authors: Fleming S C , Kapembwa M S , Griffin G E
Published: February 2014

The 14C-triolein breath test, a recognised index of fat absorption, and the p-aminobenzoic acid (PABA) test, a ‘tubeless’ test of exocrine pancreatic function, have both been widely used in the diagnosis of malabsorption and exocrine pancreatic insufficiency. This study evaluates the potential of a combination of both tests in the investigation of fat absorption and exocrine pancreatic function. Combination of the tests has become technically feasible because of the introduction of high pressure liquid chromatography as the preferred method of analysis for PABA, and use of p-aminosalicylic acid (PAS) as the marker for PABA absorption and metabolism

We studied 25 healthy subjects, 11 patients with exocrine pancreatic disease and 12 patients with gastrointestinal disease. The combined test identified subjects with reduced fat absorption and distinguished subjects with exocrine pancreatic insufficiency from those with an intestinal cause of fat malabsorption. The test could be completed in 7 h and had high patient acceptibility. These findings suggest that the combined 14C-triolein breath test and PABA test can be used as a non-invasive, 1-day investigation of fat absorption and exocrine pancreatic function.
Effect on 16 Analytes of Overnight Storage of Specimens Collected into Heparinised Evacuated Tubes with Plasma Separator
Authors: Bailey I R
Published: February 2014

Specimens taken into Becton Dickinson lithium heparin Vacutainers with plasma separator were compared with specimens taken into ordinary Becton Dickinson lithium heparin Vacutainers. After overnight storage, results for sodium, potassium, phosphate, albumin, lactate dehydrogenase, alkaline phosphatase, and urate concentrations showed statistical differences. Only the difference observed in urate concentration is likely to affect clinical interpretation.
Immunoradiometric Assay for Intact Human Parathyroid Hormone: Characteristics, Clinical Application and Comparison with a Radio-Immunoassay
Authors: Frölich M. , Walma S T , Paulson C , Papapoulos S E
Published: February 2014

Circulating immunoreactive intact human parathyroid hormone (PTH) was measured by a direct immunoradiometric assay (IRMA) and the results compared with a radio-immunoassay (RIA) which required extraction and concentration prior to assay. The sensitivity of the IRMA was better than that of the RIA (0·6 vs 2·0 pmol/L). In control subjects the hPTH concentrations ranged between 0·6 and 6·7 pmol/L and in patients with hypercalcaemia due to malignant diseases, sarcoidosis and hypoparathyroidism none could be detected. In patients with primary hyperparathyroidism the concentrations ranged from 5·2 to 27·0 pmol/L. In patients with renal osteodystrophy serum human PTH concentrations ranged from 7·6 to 285 and in those with chronic renal failure but without evidence of renal osteodystrophy from 0·5 to 5·2 pmol/L. The major advantages of the IRMA are its much simpler performance and its higher sensitivity which makes studies of the physiology of PTH secretion in humans possible.
Reference Ranges for Serum Creatinine in Infants, Children and Adolescents
Authors: Savory D J
Published: February 2014

Reference ranges for serum creatinine, derived from 2110 cases aged between 1 day and 20 years, are presented. Levels fall during the neonatal period and then increase with age in both sexes. Levels fall more rapidly in full term infants than in premature infants and are significantly higher in males than in females aged 15 years and above.
The Relationship between Serum Cholesterol and Serum Thyrotropin, Thyroxine and Tri-Iodothyronine Concentrations in Suspected Hypothyroidism
Authors: Elder J , McLelland A , O'Reilly D StJ , Packard C J , Series J J , Shepherd J
Published: February 2014

The relationship between serum cholesterol, thyrotropin, thyroxine and tri-iodothyronine was investigated in 1018 female patients over 40 years of age with suspected hypothyroidism. The correlation between serum thyrotropin and cholesterol ( r = 0.398) and between thyroxine and cholesterol ( r = — 0·217) were both highly significant ( P < 0·001), but the correlation between tri-iodothyronine and cholesterol ( r = −0·011) was not significant. Only in patients with a serum thyrotropin in excess of 40 mU/L was there a clinically appreciable increase in the serum cholesterol. In 139 patients treated for hypothyroidism by thyroxine replacement there was a highly significant correlation ( P < 0·001) between the decrease in serum thyrotropin and cholesterol ( r = 0·593). The correlation between increase in serum thyroxine and decrease in cholesterol ( r = — 0·401) was also highly significant (P < 0·001), but there was an even stronger correlation between the increase in serum tri-iodothyronine and the decrease in serum cholesterol ( r = — 0·529).
Detection of Antibodies to the Human Immunodeficiency Virus by a Silver-Enhanced Gold-Labelled Immunosorbent Assay
Authors: Rocks Bernard F , Bertram Vanessa M R , Bailey M Philip
Published: February 2014

We describe a new immunoassay for the detection of antibodies to the human immunodeficiency virus. The method is based on a silver enhanced gold-labelled immunosorbent assay (SEGLISA).

Test sera are incubated in microtitre wells on which antigens have been coated. If present in the test sera, antibodies to the human immunodeficiency virus bind to the solid-phase antigens. Bound antibodies are quantitated with anti-human immunoglobulin labelled with gold. Positive specimens produce a faint pink deposit which is better visualised by silver enhancement which gives an intense black colour. The intensity of the colour is proportional to the bound antibody concentration. All the reagents are stable and the silver enhancement takes place under ambient light conditions.

The assay has many of the advantages of micro enzyme-linked immunosorbent assays but does not suffer from the drawbacks associated with the use of an enzyme label. It requires fewer manipulations and is quicker to carry out than an equivalent enzyme-linked test. As the silver layer is permanent dried wells may be stored for future reading or checking.
A Lectin-Based Monoclonal Enzyme Immunoassay to Distinguish Fucosylated and Non-Fucosylated α-Fetoprotein Molecular Variants
Authors: Suzuki Yasufumi , Aoyagi Yutaka , Muramatsu Minoru , Igarashi Kentarou , Saito Atsuchi , Oguro Makoto , Isemura Mamoru , Asakura Hitoshi
Published: February 2014

Purified α-fetoprotein (AFP), fucosylated AFP mixtures, and 40 sera from patients with AFP-producing hepatocellular carcinoma were analysed by monoclonal enzyme immunoassay (EIA) to distinguish fucosylated and non-fucosylated AFP molecular variants. FUC—AFP–25 was discriminated from FUCAFP-75 by the EIA using monoclonal antibody 18H4 in the range of total AFP concentrations from 100 to 800 ng/mL. In addition, sera from 40 patients with hepatocellular carcinoma, with AFP concentrations from 100 to 1270 ng/mL and with fucosylated AFP from 0 to 100% by conventional cross immunoaffinoelectrophoresis, were also analysed by the present EIA. A statistically significant correlation was obtained between the data from the present EIA and from the conventional crossed immuno-affinoelectrophoresis in the range of fucosylated AFP more than 20% and the serum concentration of AFP more than 100 ng/mL. These results indicate that the present EIA is useful for clinical detection of hepatocellular carcinoma during the follow-up of patients with chronic liver diseases.
Cerebrospinal Fluid Biochemistry in the Diagnosis of Multiple Sclerosis
Authors: Ratnaike Sujiva , Kilpatrick Trevor , Tress Brian , Davis Stephen , Kilpatrick Christine , Byron Keith , Deam David
Published: February 2014

The Poser criteria for diagnosing multiple sclerosis (MS) includes clinical, paraclinical and laboratory information.1 We studied the influence of cerebrospinal fluid (CSF) biochemistry results on the categorisation of patients with suspected MS.

A retrospective study was made of 138 patients who had CSF samples sent over a 1 year period to the laboratory for examination for oligoclonal bands. Using the Poser criteria, 23 patients were diagnosed as having definite MS and one patient as probable MS. Cerebrospinal fluid biochemistry upgraded the categorisation from probable to definite MS in 16 of these 24 patients (66%).

In this study, we found oligoclonal bands to be more sensitive in the diagnosis of MS (96%) than either the concentration of IgG in the CSF (43·5%) or the IgG expressed as a percentage of the total protein in the CSF (71%). We conclude that CSF biochemistry is a valuable investigation in the evaluation of patients with suspected MS.
A Survey of Drugs of Abuse Testing by Clinical Laboratories in the United Kingdom
Authors: Burnett D , Lader S , Richens A , Smith B L , Toseland P A , Walker G , Williams J , Wilson J F
Published: February 2014

An external quality assessment survey of testing facilities in UK clinical laboratories for the detection of drugs of abuse was made with nine freeze-dried samples of urine containing representative drugs with their metabolites from the following seven classes; amphetamines and stimulants, barbiturates, cannabinoids, cocaine, minor tranquillisers, opiates and non-opiate narcotics. Reports were received from 120 laboratories. Thirty six per cent of laboratories reported on all seven drug classes and 71% on the five classes excluding cannabinoids and cocaine. A single drug screening technique was used by 32% of laboratories whilst 46% were able to perform tests by both immunological and chromatographic techniques. There was a mean level of false positive reporting of 4·3% and an observed level of false negative reports of 8·4%, the latter underestimating the true frequency. The minor tranquillisers, cocaine and benzoyl ecgonine were the most frequently missed analytes. Several false reports had important potential implications for patient care.
An Improved Cation Exchange HPLC Method for the Measurement of Serum Creatinine
Authors: Guy J M , Legg E F
Published: February 2014

An improved HPLC method for the measurement of serum creatinine is described. Separation is effected using a strong cation exchange column at pH 4·7. Analytical recovery, precision and linearity are satisfactory, and the method correlates well with a kinetic Jaffé procedure. The method provides a means of accurately measuring creatinine and may be of use in the investigation of interference in creatinine assays.
Influence of Monoclonal Immunoglobulins in Three Different Methods for Inorganic Phosphorus
Authors: Bakker Andries J , Bosma Hilly , Christen Pieter J
Published: February 2014

Three methods for the determination of inorganic phosphorus were compared in order to evaluate the frequency of falsely high concentrations of inorganic phosphorus in 102 sera containing monoclonal immunoglobulins. The results for the three methods using neat sera were compared with those obtained from protein-free filtrates of the same sera. For the neat sera erroneously high results were encountered with the molybdate method in about 10% (11/102) of the cases. In contrast neither the enzymatic method nor the modified molybdate method gave erroneous results. The presence and magnitude of error of the molybdate method bore no relationship to the type or the concentration of the monoclonal immunoglobulins. The precipitation of monoclonal immunoglobulins by the strongly acidic molybdate reagent, leading to erroneous results, can not always be prevented by the addition of a detergent. Nor can the problem be solved by a simple two- or threefold dilution.
Platelet and Plasma Vasoactive Amines in Type 1 (Insulin-Dependent) Diabetes Mellitus with and without Vascular Disease
Authors: Winocour P H , Klimiuk P. , Grennan A , Baker R D , Weinkove C
Published: February 2014

Platelet and plasma vasoactive amine concentrations were measured in healthy controls and in type 1 (insulin-dependent) diabetic patients with or without vascular disease. Platelet concentrations of serotonin and noradrenaline were similar in all groups and were unrelated to age or gender, or to duration of diabetes, blood pressure, glycaemia or renal function in the diabetic subjects. Plasma concentrations of serotonin in the diabetic groups were comparable (118 ± 16 (mean ± SEM) and 127 ± 21 pmol/mL), and were significantly higher in comparison to the healthy controls (66 ± 12 pmol/mL, P = 0·002).
Pseudohypophosphataemia as a Result of Bilirubin Interference
Authors: Duncanson G O , Worth H G J
Published: February 2014

During the routine use of a discrete analyser it was noted that, when the serum bilirubin concentration was greater than 50 µmol/L, there was interference with serum phosphate determination measured by the formation of unreduced phosphomolybdate using a bichromatic system of measurement. The degree of interference was assessed by comparison with a reduced phosphomolybdate method (molybdenum blue). The interference cannot be removed by changing the secondary wavelength or by the use of a sample blank. It is proportional to the serum bilirubin concentration, but is not significant when this is less than 50 µmol/L. The monochromatic non-reduced phosphomolybdate method compares well with the reduced method.
Biochemical Investigation of Hypertension
Authors: Harvey J M , Beevers D G
Published: February 2014

Underlying causes of hypertension are found in less than 5% of cases but they are frequently surgically remediable. Elementary biochemical tests are usually sufficient to exclude most renal and endocrine causes of hypertension. However, young patients with very high blood pressures merit more detailed investigation in specialized centres.

As coexistent hyperlipidaemia or glucose intolerance substantially worsen the prognosis for a given level of blood pressure, these two risk factors are worth assessing in all hypertensive patients. Their presence may also alter the choice of antihypertensive drug therapy. About 25% of the population have raised blood pressure at first screening and about 10% are in need of drug therapy, so this represents an appreciable load on biochemical laboratories. Most patients, however, need only a single biochemical profile on one occasion, and should be exclusively managed in general practice.
Atrial Natriuretic Factor in Untreated Hyperthyroidism
Authors: Widecka Krystyna , Gozdzik Jolanta , Dutkiewicz Tomasz , Majewska Urszula , Czekalski Stanislaw
Published: February 2014

Increased plasma concentration of atrial natriuretic factor (ANF) in untreated hyperthyroid patients is reported. A significant positive correlation between the concentration of ANF and serum thyroid hormones (T4 and T3) has been found when hyperthyroid patients and healthy controls were pooled together. The mechanism by which thyroid hormones raise plasma ANF concentration and its relevance to the symptomatology of hyperthyroidism is discussed.
An Immunochemical Evaluation for the Identification and Typing of Monoclonal Proteins
Authors: Fifield Richard , Keller Ivan
Published: February 2014

Using automated measurements of kappa (κ) and lambda (λ) light chain and IgG, IgA and IgM concentrations we assessed the ability of the κ/λ ratio and the heavy/light chain ratio to identify and type monoclonal components which had been previously identified by serum protein electrophoresis and immunoelectrophoresis. We examined 1151 samples, of which 277 contained monoclonal components; 90% of the monoclonal proteins could be identified by this approach, of which 95% were correctly typed. In addition 19 of 874 samples without monoclonal components showed an abnormal κ/λ ratio. We assessed the ability of the immunochemical evaluation to calculate monoclonal component concentration and then compared the results to the scanning densitometry of serum protein electrophoresis.
Estimation of Paraproteins by Immunoturbidimetry and Electrophoresis Followed by Scanning Densitometry
Authors: Sinclair David , Ballantyne Fiona , Shanley Susan , Caine Eleanor , O'Reilly Denis , Shenkin Alan
Published: February 2014

A comparison of paraprotein estimation by immunoturbidimetry (IT) and electrophoresis followed by scanning densitometry (EFD) showed significant differences in concentration for IgG, IgA, and IgM paraproteins. Overestimation of IgM paraproteins by IT was particularly marked. Our data suggest that both techniques should be used for IgG and IgA paraproteins but for IgM paraproteins IT was found to be unsuitable and EFD is the method of choice.
Stability of Plasma Glucose during Storage
Authors: Clark M L , Humphreys S M , Frayn K N
Published: February 2014

Plasma glucose concentrations were found to decrease during storage. This phenomenon was not method-dependent; it was demonstrated using both a Beckman Glucose Analyser 2 (based on glucose oxidase) and a hexokinase-based technique on a centrifugal analyser. The loss of glucose was typically of the order of 10% in plasma frozen for periods from 24h to 14 months. Repeated freezing and thawing (weekly for 1 month) did not produce additional loss of glucose compared with aliquots thawed for the first time at 1 month. Fluoride did not reduce the loss of glucose. Glucose was also lost from frozen neutralized perchloric acid extracts of blood (mean ± SD: 7 ± 2 per cent over 1 year). We conclude that this variable loss of glucose on storage may complicate the interpretation of metabolic research procedures.
Delayed Diagnosis of Addison's Disease
Authors: Paterson J R , Neithercut W D , Spooner R J
Published: February 2014

Addison's disease may be difficult to diagnose because of the nonspecificity of the most frequently occurring symptoms. Hyponatraemia, hyperkalaemia, and uraemia are commonly detected in sera from patients with Addison's disease. We report two patients in whom the diagnosis was delayed, despite typical biochemical abnormalities in their sera during initial presentation. A computer search of 4 weeks of biochemical data (9862 requests for electrolytes) indicated that these typical biochemical abnormalities occurred commonly in other patients, increasing the difficulty of the clinical biochemist in detecting Addison's disease. Awareness of this problem, in combination with adequate clinical information, should enable the clinical biochemist to assist in the earlier diagnosis of Addison's disease.
Isoelectric Focusing of Cerebrospinal Fluid Immunoglobulin G: An Annotated Update
Authors: Keir G , Luxton R W , Thompson E J
Published: February 2014

A revised agarose isoelectric focusing method for detecting oligoclonal IgG in unconcentrated cerebrospinal fluid is presented. The technique is shown to be robust and reproducible and suitable for the detection of intrathecal IgG synthesis.
Clinical Significance of the Immunometric Measurements of Hyaluronic Acid
Authors: Cooper E H , Rathbone B J
Published: February 2014

Hyaluronic acid (HA), an unbranched high molecular weight polysaccharide can now be measured by several immunometric assays. The connective tissues are the main source of HA and it is destroyed mainly in the liver. Very high levels of HA occur in mesothelioma, Wilms' tumour and acute liver failure, and moderate increases in rheumatoid diseases, renal failure and cirrhosis. Local increased production of HA is a feature of several forms of lung disease. HA is an indicator of connective tissue turnover, of the function of the receptor mechanisms for its capture and destruction by the liver, and of the removal of low molecular weight fragments by the kidney.
The Measurement of Lipoprotein Subfractions in Plasma Using a Tabletop Ultracentrifuge
Authors: Cathcart S , Dominiczak M H
Published: February 2014

We adapted the ultracentrifugation method of the Lipid Research Clinics Program for the separation of lipid subfractions (LDL, VLDL and HDL cholesterol) to a tabletop ultracentrifuge (Beckman TL-100). Centrifugation time was reduced from 18 h to 2·5 h and the sample volume from 5 mL to 2 mL plasma. The imprecision of the LDL-cholesterol estimation (coefficient of variation = CV) was 2·9–7·4% and that of HDL-cholesterol measurement was 1·4–3·9%. Imprecision of the VLDL-C measurement was high (CV = 15·6–29·8%). The results correlated with those obtained by the Lipid Research Clinics method ( P < 0·001). Our method could be conveniently adapted by clinical laboratories serving specialist lipid clinics.
Sex Hormone Binding Globulin: Origin, Function and Clinical Significance
Authors: Selby Colin
Published: February 2014

Sex hormone binding globulin (SHBG) is a glycoprotein possessing high affinity binding for 17 β-hydroxysteriod hormones such as testosterone and oestradiol. It is probably synthesized in the liver, plasma concentrations being regulated by, amongst other things, androgen/oestrogen balance, thyroid hormones, isulin and dietary factors. it is involved in transport of sex steroids in plasma and its concentration is a major factor regulating their distribution between the protein-bound and free states. Its detailed role in the delivery of hormones to target tissues is not yet clear.

Plasma SHBG concentrations are affected by a number of different diseases, high values being found in hyperthyroidism, hypogonadism, androgen insensitivity and hepatic cirrhosis in men. Low concentrations are found in myxoedema, hyperprolactinaemia and syndromes of excessive androgen activity. Concentrations are also affected by drugs such as androgens, oestrogens, thyroid hormones and anti-convulsants.

Measurement of SHBG is useful in the evaluation of mild disorders of androgen metabolism and enables identification of those women with hirsutism who are more likely to respond to oestrogen therapy. Testosterone: SHBG ratios correlate well with both measured and calculated values of free testosterone and help to discriminate subjects with excessive androgen activity from normal individuals.
Non-Isotopic, Two-Step Free Thyroxine Immunoassay: A Better Measure of Free Thyroxine than Analogue Radioimmunoassay
Authors: Beckett G J , Ratcliffe W A , Chapman B , Wu P , Rae P W H , Gow S M , Toft A D
Published: February 2014

Plasma or serum free thyroxine (T4) was measured by a novel non-isotopic, two-step immunossay in 373 consecutive patients attending a thyroid clinic, in whom thyroid status was categorized according to clinical findings, supported by routine thyroid function tests. The 95% confidence limit of free T4 in the euthyroid patients ( n = 112) was 7–20 pmol/L. Free T4 concentrations within the reference range were found in six of 40 patients with primary hypothyroidism and nine of 182 patients with overt thyrotoxicosis, six of whom had T3 toxicosis. Serum or plasma free T4 measured by the two-step method showed improved diagnostic specificity over an analogue RIA in selected groups of euthyroid patients in whom abnormal binding of analogue T4 can affect the validity of the result. Free T4 results found by analogue RIA and the two-step method in 58 patients who were receiving thyroxine replacement therapy were similar. The between-assay precision of the two-step method was poor ranging from a coefficient of variation of 9·7% to 19·3% over a free T4 concentration range of 5·0 to 46·0 pmol/L. We conclude that the two-step methodology offers diagnostic advantages for a laboratory which receives specimens from such patients for exclusion of thyroid disease but that improved assay precision is required before it could be used in a routine situation.
Hepatic Changes and Serum Ferritin in Pancreatic Cancer and other Gastrointestinal Diseases: The Role of Cholestasis
Authors: Basso Daniela , Fabris Carlo , Del Favero Giuseppe , Meggiato Tamara , Panozzo Maria Piera , Vianello Daniela , Plebani Mario , Naccarato Remo
Published: February 2014

Serum ferritin, prealbumin, pseudocholinesterase, α-1-antitrypsin and caeruloplasmin were determined in control subjects and patients with pancreatic cancer, chronic pancreatitis or extra-pancreatic disease mainly of gastrointestinal origin, in order to investigate the different hepatic changes which influence serum ferritin in chronic pancreatic and other digestive diseases. Increased circulating ferritin was found in pancreatic cancer and extra-pancreatic disease when compared to controls.

Correlations were detected between ferritin and the other proteins investigated and between ferritin and total bilirubin, alkaline phosphatase and alanine aminotransferase. Multiple regression analysis demonstrated that cholestasis accounts for 45% of circulating ferritin, the acute-phase response accounted for 18% and decreased liver function accounted for 11%. We conclude that the increase in serum ferritin in chronic pancreatic and other gastrointestinal diseases largely depends on liver changes, with cholestasis probably playing a primary role.
Protein Interference with Ion-Selective Electrode Measurement Depends on Reference Electrode Composition and Design
Authors: Payne R B , Buckley B M , Rawson K M
Published: February 2014

There is controversy about whether protein interferes with ion measurements using ion-selective electrodes. We have investigated the effects of changes in the salt-bridge composition of five commercially available analysers with open, membrane-restricted or porous frit-restricted reference electrode junctions on measurements of an albumin solution prepared by gel filtration. When the manufacturers' salt bridges were used, instruments with open or membrane-restricted junctions showed apparent increases in the activity of ionized calcium, sodium and potassium in the presence of protein. When the hypertonic bridge solutions were replaced with 150 mmol/L potassium chloride this increase disappeared. The instrument with a porous frit-restricted junction showed no protein effect, but its response to changes in sample sodium chloride concentration in protein-free solution suggested that its junction was functionally equivalent to that formed with an isotonic sodium chloride bridge. Our results emphasize that liquid junction design and composition affect ion measurements in protein-containing solutions and suggest that the use of hypertonic bridge solutions for biological samples needs to be re-examined.