bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development and Evaluation of an Enzyme Inhibition Assay for Methotrexate
Authors: Kelly Michael G 
Published: February 2014

A method for the measurement of methotrexate based on its inhibition of dihydrofolate reductase (EC 1.5.1.3) is described. The performance of the method is evaluated and a brief assessment of its clinical usefulness made. Reaction time, pH, and the relative concentration of enzyme and inhibitor all have a significant effect on the shape of the standard curve. Pre-incubation of enzyme with methotrexate resulted in increased inhibition, but did not improve the sensitivity or linearity of the assay. Data are presented on the imprecision, specificity and accuracy of the method. The method is simple to perform, rapid and inexpensive. The sensitivity and specificity of the method are such as to allow for effective monitoring of patients on methotrexate therapy.
Detection of Antibodies to the Human Immunodeficiency Virus by a Rapid Fluorescence-Labelled Immunosorbent Assay
Authors: Rocks Bernard F , Bertram Vanessa M R , Bailey M Philip , Riley Clifford , Thom Barry T 
Published: February 2014

The development and assessment of a fluorescence-labelled immunosorbent assay for the detection of antibodies to the human immunodeficiency virus is described. Test serum is incubated in microtitre wells on which antigens have been coated. If present in the test serum, antibodies to the human immunodeficiency virus bind to the solid-phase antigens. In turn the antibodies are quantified with anti-human immunoglobulin labelled with fluorescein. Positive samples produce an intense fluorescence which is measured in a spectrofluorimeter. When used to test a panel consisting of normal serum and antibody-positive serum from infected patients the assay proved to be 100% specific and to have a sensitivity of 100%. 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.
A Study of the Hypouricaemic Effect of Tiaprofenic Acid
Authors: Lyfar Vivienne , Fernandes L , Thornton Elizabeth , Cook J G H 
Published: February 2014

Tiaprofenic acid is a non-steroidal anti-inflammatory drug which also has hypouriceamic effect. Studies involving 10 healthy volunteers were designed to investigate the mode of this effect. We postulate that the site of action of tiaprofenic acid is at the cell membrane, the mechanism being an interference with the transport of uric acid from intra- to extra-cellular fluid thus limiting its passage into the plasma. The same mechanism acting on renal tubular cells impedes reabsorption thereby increasing uric acid clearance.
Long-Term Performance of the Fructosamine Assay
Authors: Dominiczak M H , Macrury S M , Orrell J M , Paterson K R 
Published: February 2014

We have investigated the long-term performance of the fructosamine assay based on secondary glycated protein standards and attempted to define the interpretation of varying degrees of increase in fructosamine concentration in comparison to haemoglobin A1 (HbA1) values both in insulin dependent (IDDM) and non-insulin dependent (NIDDM) diabetic patients. Between-batch imprecision of fructosamine over 5 months was (CV) 2·5% at 2·09 mmol/L, 2·8% at 3·52 mmol/L and 3·6% at 4·14 mmol/L. Variation of fructosamine concentration in vivo in stable diabetic patients monitored over 8–18 weeks was 2·3% to 7·1%. Fructosamine correlated with HbA1 both in IDDM ( n = 110, r = 0·701, P < 0·001) and NIDDM ( n = 71, r = 0·764, P < 0·001). Specificity and sensitivity of fructosamine for the prediction of degree of control assessed on the basis of HbA1 level (cut-off point for good vs. poor control, HbA1 = 10%) was determined. In NIDDM, specificity above 90% was achieved at a fructosamine concentration of 3·4 mmol/L with a corresponding sensitivity of 64·1%. 22·5% of patients were classified differently on the basis of fructosamine as compared to HbA1. In IDDM, specificity over 90% was achieved at 3·8% mmol/L fructosamine with a sensitivity of 35%. Discordancy rate between HbA1 and fructosamine based assessment of control was 31·8%. The assessment of diabetic control based on fructosamine may be different from that based on HbA1, particularly in IDDM. Fructosamine and HbA1 should be used as complementary rather than alternative tests.
Evaluation of Red Blood Cell Size Distribution Histograms: The Fraction of Microcytes
Authors: Bartels P C , Helleman P W , Soons J B J 
Published: February 2014

A method is described for the assessment of the fraction of microcytes from the red blood cell (RBC) size distribution histogram. For quantification of the fraction of microcytes an upper threshold corresponding with a RBC volume of 70 fL is established. The reference interval for the fraction of microcytes covers a range from 0·01 to 0·09. In order to examine the relationship between the fraction of microcytes and the mean cell volume (MCV) values computer simulation studies were performed. The computer simulations are based on a Gaussian distributed reference RBC histogram as generated on a Technicon H 6000/H 601 Hematology Analyser. From our studies it is shown that determination of the fraction of microcytes yields a higher sensitivity than MCV values for detecting small populations of microcytes. In particular, measurement of the fraction of microcytes is very sensitive to minor changes in the MCV values if a normocytic RBC population combined with a microcytic RBC fraction shows a wide dispersion in their cell volumes.
The Evaluation of Erythrocyte Thiamin Diphosphate as an Indicator of Thiamin Status in Man, and its Comparison with Erythrocyte Transketolase Activity Measurements
Authors: Baines M , Davies G 
Published: February 2014

HPLC measurement of the major physiological form of thiamin, thiamin diphosphate, in erythrocytes (ETDP) has been assessed as an indicator of thiamin status and compared with erythrocyte transketolase activity (ETKA) before and after activation with exogenous thiamin diphosphate (TDP effect). The comparison was made by following the response of the parameters to incubation of erythrocytes with thiamin and by measurements in alcoholic, elderly and student groups. All parameters were responsive to the thiamin content of their environment, but ETDP was at least as sensitive as TDP effect and more sensitive than ETKA in reflecting thiamin uptake and utilisation by erythrocytes. There was a better correlation between ETDP and ETKA than between ETDP and TDP effect. All the groups showed a significant positive correlation between ETDP and ETKA, but only the elderly and the alcoholic groups showed a significant negative correlation between ETDP and TDP effect. The lack of correlation between ETDP and TDP effect in the student group may be due to the relative imprecision of TDP effect measurements at the lower end of the reference range. ETDP is more stable than ETKA in frozen erythrocytes, is easier to standardise and is not affected by various factors which can influence the enzyme assay. Measurement of ETDP is, therefore, recommended for first line assessment of thiamin status.
Serum Fructosamine in Uraemia, Myeloma and Acute Inflammatory Disorders—Relationship to Serum Glucose and Albumin Levels
Authors: McCance D R , Clarke K C , Kennedy L 
Published: February 2014

There has been considerable interest in the serum fructosamine assay as a measure of glycated serum proteins. We have measured serum fructosamine in three groups of patients—those with uraemia; those with multiple myeloma; and those with acute inflammatory conditions—none of whom were known to have diabetes. Serum fructosamine was significantly higher in the uraemic group than in the other two, and also than in a control group. When allowance was made for prevailing serum albumin levels fructosamine was shown to be increased in the acute inflammatory group also. There was a significant correlation between random plasma glucose and serum fructosamine only when fructosamine was adjusted for prevailing albumin levels. In control and uraemic subjects there was a significant positive correlation between serum fructosamine and albumin levels, whereas in the myeloma group there was a negative correlation with serum protein. These data would suggest the need to take into account serum albumin levels and protein composition if serum fructosamine is accurately to reflect short-term integrated glycaemia.
The Effect of Supplementation with Selenium and Vitamin E in Psoriasis
Authors: Fairris G M , Lloyd Barbara , Hinks Lesley , Perkins Pauline J , Clayton Barbara E 
Published: February 2014

Since reduced concentrations of selenium in whole blood, plasma and white cells had previously been observed in psoriasis, 69 patients were supplemented daily with either 600 μg of selenium-enriched yeast, 600 μg of selenium-enriched yeast plus 600 IU of vitamin E or a placebo for 12 weeks. Before supplementation, the patients' mean concentrations of selenium in whole blood and plasma were reduced compared with those of matched healthy controls but their red cell glutathione peroxidase (GSH-Px) activity was normal. After 12 weeks supplementation the patients' mean whole blood, plasma and platelet selenium concentrations, platelet GSH-Px activity and plasma vitamin E concentration had risen significantly from the baseline values but their mean skin selenium concentration and red cell GSH-Px activity remained unchanged. The mean white cell selenium concentration rose only in the group receiving selenium alone. Neither supplementation regimen reduced the severity of psoriasis or produced side-effects. The increase in platelet GSH-Px activity suggests that the supplements were bioavailable and that the patients' selenium status may have been reduced prior to supplementation. The failure of the selenium content of the skin to increase may explain why the patients' psoriasis remained unchanged during supplementation.
Serum Protein Electrophoresis: Italian Survey 1986
Authors: Aguzzi F , Petrini C , Gasparro C 
Published: February 2014

In 1986 the Protein Commission of the Italian Society of Clinical Biochemistry (SIBIOC) carried out its second survey on the use of serum protein electrophoresis in Italian laboratories. Three serum samples plus a questionnaire were sent to the 253 laboratories which agreed to take part. The three samples had the following characteristics: Serum 1: a 60 g/L IgM-lambda monoclonal component (MC); Serum 2: an artificially split alpha-2 zone; Serum 3: a very faint lambda chain MC. These features were chosen to assess (a) the type of report; (b) the resolution quality of the electrophoretic technique; and (c) the laboratory capacity to detect a small MC. The most significant features revealed by the survey were: (a) the poor capacity of assessment of the small MC in Serum 3 (only detected by 23·1% of laboratories); (b) the discouraging tendency to delegate electrophoretic diagnostic interpretation to ward physicians (44·4% of participating laboratories provided only densitometric values and graphs).
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.
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.
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.
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.
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.
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.
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.
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.