bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Laboratory Tests in Hospitals
Authors: Stilwell JA , Young D , Cunnington A
Published: February 2014

The use of laboratory tests in the management of 174 randomly selected patients admitted as acute medical emergencies was monitored in detail. The occasions when a test result changed patient management, and the nature of that change, were noted. Tests were classified according to information yielded and the importance of any action taken. For biochemistry alone every test result was costed. A ranking for all tests was produced, in terms of expected actions per test, and for biochemistry a ‘value for money’ table giving actions per pound spent. Every test request was classified as either discretionary or non-discretionary. The discretionary category was further subdivided into diagnostic and monitoring. The values, in terms of action-producing results, of non-discretionary, diagnostic, and monitoring tests were compared, and this comparison showed that the cost per item of helpful information was about £10 for diagnostic, £23 for monitoring, and £20 for non- discretionary tests. In total, £1790 was spent, and 28 items of unique information were yielded, enabling clinicians to discharge five patients, take seven courses of action which would have had serious consequences if omitted, and 16 actions the omission of which would have led to very serious consequences.
Evaluation of the Kodak Ektachem Glucose and Urea Methods
Authors: Clark Penelope M S , Kricka Larry J , Whitehead Thomas P
Published: February 2014

An evaluation of the Kodak Ektachem glucose and urea methods is described. Aspects evaluated included precision, linearity, accuracy, correlation with routine methods, interferences (haemoglobin, bilirubin, protein, dextran, lipaemia, ethylene-diamine tetraacetic acid, fluoride/oxalate, and heparin), and carryover. Stability and batch-to-batch variation in glucose and urea reagents were also investigated.

The performance of the Ektachem glucose and urea methods was shown to be as satisfactory as conventional analytical methods. The requirement to reconstitute control serum samples in a bicarbonate diluent in order to obtain accurate results presents problems for the analysis of lyophilised specimens circulated by external quality assessment schemes. The complex calibration model and the significance of variation in the calibration parameters need further explanation. The Ektachem methods are designed specifically for use with human serum. However, the methods performed satisfactorily with cerebrospinal fluid, pleural effusions, and animal serum but not with urine.
Evaluation of a Commercial Enzymatic Method for the Determination of Total Serum Bile Acids
Authors: Tobiasson Per , Källberg Magnus
Published: February 2014

An enzymatic method (Sterognost-3α® Flu, Nyegaard & Co, Oslo, Norway) for the determination of total serum bile acids has been evaluated, and reference values for fasting and postprandial total serum bile acids have been established. Precision was rather low in the lower normal range but satisfactory in the upper reference range and for elevated values. The upper reference value for fasting total serum bile acids was 5·0 μmol/l. Maximal postprandial elevations occurred at varying intervals after a test meal and the upper postprandial reference value was 12 μmol/l. Certain serum samples were also analysed by radioimmunological methods for conjugates of cholic and chenodeoxycholic acids. The values obtained with the enzymatic method correlated satisfactorily with those of the radioimmunoassay methods for most of the serum samples analysed. However, a number of samples with slightly elevated bile acid concentrations, as measured by the comparison radioimmunoassay methods, were found to have normal total serum bile acids when measured by the enzymatic method.
Comparison of Digoxin Analysis by EMIT with Immophase and Dac-Cel Radioimmunoassay
Authors: Rumley Alan G , Trope Angela , Rowe David J F , Hainsworth Ian R
Published: February 2014

The results obtained by an enzyme multiplied immunoassay kit, EMIT, for the measurement of serum digoxin concentration were compared with those from two radioimmunoassay kit methods, Immophase and Dac-Cel. Patients' sera were used to study the correlation between the methods, and three quality control sera with low, intermediate, and high digoxin concentrations were used to study individual method precision. The coefficients of correlation between the three methods varied between 0·915 and 0·951 for serum drug concentrations up to 4·5 nmol/l. There were statistically significant differences between the means of the patients' samples for each method. Precision was acceptable for each method: within-batch percentage coefficient of variation (%CV) < 8, between-batch % CV < 10, except for Dac-Cel at low concentration % CV = 18·6. The time taken for the analysis of a batch of 10 samples was between 1 • 5 and 2 hours, depending on the method.
Failure to Induce Reactive Hypoglycaemia by Drinking a Starch-Based Alcohol Beverage (Sorghum Beer)
Authors: Joffe B I , Roach L , Baker S , Shires R , Sandler M , Seftel H C
Published: February 2014

Alcohol is a well-recognised cause of fasting hypoglycaemia but may also provoke reactive hypoglycaemia when drunk together with a carbohydrate mixer. In this study the ability of sorghum beer (an ‘in-built’ alocohol-starch beverage widely enjoyed in Southern Africa) to induce reactive hypoglycaemia was compared with ‘gin and tonic’ in eight non-obese healthy African men. After an overnight fast, each subject drank, in random sequence on three different occasions, 2 litres of sorghum beer (carbohydrate content approximately 5% and alcohol concentration 2·24 g/dl–2·8% v/v), the same volume of a control solution providing a similar carbohydrate load, or a gin and standard tonic water mixture. No evidence of reactive hypoglycaemia was apparent during the 5 hours after the beginning of the sorghum beer tolerance tests, despite a mean peak blood alcohol level reaching 80 mg/dl. Both the peak and total plasma insulin responses were significantly reduced (p≤0·05) when compared to the brisk responses elicited by the carbohydrate solution alone and the gin and tonic drinks, with consequent hypoglycaemia. These data suggest that African home-brews are not potent causes of reactive hypoglycaemia, although they may be implicated in the development of ethanol-induced hypoglycaemia in the fasting state.
Analytical Errors in Clinical Laboratories as Assessed by An Interlaboratory Survey
Authors: Lever M , Munster D J , Walmsley T A , Stewart A W
Published: February 2014

Combined errors are the commonest systematic errors in laboratory results and occur with most tests studied. In these errors, results are reduced (or, less commonly, increased) by a factor, and this effect is compensated by the addition (or subtraction) of a constant amount. The effect is that results are in error in opposite directions at high and low levels. Inconsistency is predominant and is due mainly to imprecision, although for some tests (iron, cholesterol, calcium, and triglycerides among those studied) other factors such as non-specificity are significant. An interlaboratory survey based upon external method assessment using linear regression analysis provided objective information about analytical error in laboratories which is not usually obtained, while at the same time meeting the usual functions of surveys in the quality audit of performance.
A Radioimmunoassay for Ethinyl Oestradiol in Plasma Incorporating an Immunosorbent, Pre-assay Purification Procedure
Authors: Dyas J , Turkes A , Read G F , Riad-Fahmy Diana
Published: February 2014

A radioimmunoassay for plasma ethinyl oestradiol, featuring an immunosorbent extraction procedure, is described. Ethinyl oestradiol (EE2) was extracted using a non-specific, anti-oestrogen serum, raised to an oestradiol-17-hemisuccinate conjugate. The antiserum, coupled to microcrystalline cellulose, selectively extracted EE2 but not norethisterone (NE), thus conferring specificity on a radioimmunoassay which has previously exhibited unacceptably high cross-reactivity with the synthetic progestagen, norethisterone, often used concomitantly with ethinyl oestradiol. This radioimmunoassay was shown to fulfil accepted assay validation criteria. Levels in subjects not receiving EE2 were less than 25 pmol/l. Circulating concentrations of EE2 could therefore be accurately determined in patients receiving low-dose combined preparations (EE2 35 μg; NE 500 μg).
Oxidase Determination of Plasma Cholesterol as Cholest-4-En-3-One Using Iso-Octane Extraction
Authors: Trinder Paul
Published: February 2014

Cholesterol esters in 20 μl of plasma are hydrolysed with hot ethanolic KOH. Preformed cholesterol and cholesterol released by hydrolysis is reacted with cholesterol oxidase to form hydrogen peroxide and cholest-4-en-3-one, which is extracted from alkaline 50% v/v ethanolic solution with iso-octane. The absorbance of the ketone in iso-octane at the 232 nm peak is used to measure the cholesterol originally present. Plasma blanks obtained by omitting the cholesterol oxidase from the reagent show negligible absorbance even when the samples are grossly icteric, lipaemic, or haemolysed. The test is carried out in a single glass screw-capped tube, and the absorbance given by a sample containing 6·25 mmol/l cholesterol is ≏ 0·44, corresponding to a molar absorbance of ≏ 17 500. The conversion of cholesterol to cholest-4-en-3-one is stoichiometric, and the absorbance of the iso-octane layer is stable for at least 48 hours. A single determination occupies 30 minutes; 30 samples can be analysed in 1½ hours.
Simple Adaptation of the Technicon SMAC System to Operate 18 Channels with Reduced Volumes of Plasma
Authors: O'Leary Niall , Hurley Tadgh , Stapleton Mary , Scully Barbara , Duggan P Finbarr
Published: February 2014

The Technicon SMAC system was adapted to function with much smaller volumes of plasma than those used in standard procedures. With only minimal operator-entered changes to the 7·6 computer program, and simple modifications of the glucose and alkaline phosphatase channels, the SMAC analyser performed equally well when the plasma volume was decreased from 235 μl sequentially down through 176 μl, 142 μl, and 105 μl. The basic principle employed was to maintain a constant flow rate of diluted sample plus diluent with decreasing sample size. The instrument proved to have the capability of operating successfully on all channels with lower signals than those encountered with the unmodified system.
Partial Characterisation of an Oncofetal Pancreatic Antigen
Authors: Knapp M L
Published: February 2014

An oncofetal pancreatic antigen (OPA) has been identified and purified from the blood of patients with pancreatic cancer. Characterisation studies on OPA have shown that it is a protein of molecular weight 40 000 with α2 electrophoretic mobility. OPA is clearly different from alpha-fetoprotein, carcinoembryonic antigen, ferritin, acute phase reactants, and normal serum proteins.

A rocket immunoassay has been developed allowing the quantitation of OPA in serum; it has been applied to samples from over 700 individuals with a variety of conditions. Elevated levels of OPA have been found in 42 of 48 (88%) patients with biopsy-proven pancreatic cancer and in a much smaller percentage of patients with other cancers or with other conditions considered in the differential diagnosis of pancreatic cancer. The studies indicate that serum OPA measurements may be useful as a preliminary screening test for pancreatic cancer and for monitoring the course of the disease.
Evaluation of the Polyethylene Glycol Precipitation Method for the Estimation of High-Density Lipoprotein Cholesterol
Authors: Briggs Catherine J , Anderson Deborah , Johnson P , Deegan T
Published: February 2014

Treatment of fresh sera with polyethylene glycol 6000 at a final concentration of 100 g/l produced selective precipitation of low-density lipoproteins with only traces of contamination with high-density lipoproteins, as determined by electroimmunoassay using antisera to human α1-lipoprotein and human β-lipoprotein. Supernatants collected for high-density lipoprotein-cholesterol estimation were free from low-density lipoproteins. Precipitates sedimented readily from specimens with high triglyceride contents, and secondary precipitation during enzymatic cholesterol determinations was absent. Values obtained by this method correlated well with those obtained by precipitation of low-density lipoproteins with heparin and manganous ions at concentrations optimal for discrete separation of lipoprotein classes (r = 0·975; P<0·001).
A Technique for the Objective Assessment of Routine Analytical Methods in Clinical Laboratories Using Pattern Recognition
Authors: Jansen Rob T P , Pijpers F W , De Valk G A J M
Published: February 2014

A technique is presented to assess objectively the reliability of analytical methods used routinely in clinical laboratories. From the Netherlands National Coupled External/Internal Quality Control Programme information can be gathered about the performance of routine analytical methods. The performance of a method in a trial is described by four ‘features’: the accuracy of a method; its day to-day precision; its susceptibility to give erroneous results (eg, extreme bias, drift, extreme week-to-week variations); and its susceptibility to give systematic errors for different laboratories. These four features obtained in a trial for a given analytical method determine the position of a ‘pattern’ in the four-dimensional space. The results of six trials discussed in this paper provided six ‘patterns' per analytical method. Using pattern recognition techniques, clusters of patterns were detected in the four-dimensional space. A weighting procedure revealed the relative importance of the various features for discrimination between the detected clusters. For various blood components, different features are of importance for this discrimination. Patterns belonging to the same clusters appeared to be patterns of the same (or comparable) analytical methods; thus analytical methods could be distinguished from each other. The means of the feature values of the patterns in a cluster determine the quality of that cluster. Thus the quality of an analytical method can be objectively assessed. Some tentative conclusions on the validity of analytical methods are given.
Sex Hormone Binding Globulin: Effect of Synthetic Steroids on the Assay and Effect of Oral Contraceptives
Authors: Bowles Susan M , Mills Richard J
Published: February 2014

The effect that synthetic steroid components of different oral contraceptives have on the assay system for measurement of sex hormone binding globulin (SHBG)-binding capacity, has been examined. Interference with the assay was not demonstrable at therapeutic levels of the drugs. d-Norgestrel was the only steroid studied which bound to SHBG with an affinity comparable to the endogenous sex hormones; it also tended to decrease SHBG-binding capacity, whereas preparations containing low levels of norethisterone increased the binding capacity. We suggest that measurement of changes in SHBG-binding capacity in subjects taking oral contraceptives may prove useful in indicating changes in sex hormone balance, particularly in view of the well-recognised side-effect of these drugs.
Comparison of Procedures for the Measurement of the Anodal Isoenzymes of Lactate Dehydrogenase in Serum
Authors: Foo A Y , Nemesànszky E , Rosalki S B
Published: February 2014

Lactate dehydrogenase (LD) isoenzyme-1 levels (LD1) determined after immunoprecipitation of M-subunits, LD1 activity by electrophoresis, and the activities of α-hydroxybutyrate dehydrogenase (HBD), urea-stable LD, and heat-stable LD, by Association of Clinical Biochemists Proposed Methods, were examined for their ability to differentiate between serum samples from patients with cardiac or liver disease. Compared with total LD, all methods gave higher serum activity in patients with cardiac disease than in those with liver disease. Differentiation between patient groups was greatest for LD1 by immunoprecipitation, followed by heat-stable LD and LD1 by electrophoresis. HBD and urea-stable LD both gave less discrimination, with negligible difference between these two procedures. LD1 activity by immunoprecipitation correlated well with LD1 activity determined by isoenzyme electrophoresis with densitometric scanning. The advantages and disadvantages of the various procedures are considered.
Limitations concerning the Use in Children of the Relationship between Plasma Creatinine and Body Height to Derive Glomerular Filtration Rate
Authors: Evans G O , Griffiths P D
Published: February 2014

The value of the formula,

[Formula: see text]

was assessed over a two-year period in 314 children aged 1 month to 17 years by comparing simultaneously determined 51Cr EDTA slope clearance and plasma creatinine measurements, and in 225 children aged 1 month to 16 years comparing with duplicate short-term creatinine clearance determinations. The relationship with 51Cr EDTA slope clearance is best in patients over the age of 3 years with clearance rates below 60 ml. min−1/l · 73m2 but even so is subject to doubt over a wide range. The relationship with creatinine clearance shows less scatter at higher levels of clearance but the same doubt exists when it is used as an estimate of glomerular filtration rate.
A Novel Five-Microlitre Capillary System for Home Glucose Monitoring
Authors: Williams C P , Davies G K , Child D F
Published: February 2014

Improvement in the control of diabetic patients is aided by a knowledge of blood glucose levels during a ‘normal’ (non-hospitalised) day. We have devised a 5 μl capillary tube collection system as a ‘kit’ for home use by diabetics. Blood collected into 5 μl capillary tubes is washed into a protein precipitant by the patient. The completed kit is posted to the laboratory for analysis. The technique has achieved a high degree of patient acceptability. Subsequent analysis involves the addition of a single reagent. Reagents, patient samples, and standards are stable, and the precision of the technique compares favourably with our routine glucose procedure.
Monitoring Induction of Ovulation by Rapid Radioimmunoassays of Oestrogen and Pregnanediol Glucuronides
Authors: Maclean A R , Outch K H , Russell J M , Brown J B , Dennis P M
Published: February 2014

To increase the sample-handling capacity for an induction of ovulation programme, direct urinary radioimmunoassays (RIA) for three steroid glucuronides, pregnanediol-3-glucuronide (Pd-3-G), oestrone-3-glucuronide (E1-3-G), and oestriol-16α-glucuronide (E3-16-G), were established. Results obtained for urinary Pd-3-G measured by direct RIA show an excellent correlation (r = 0·98, N = 46) with those for urinary pregnanediol measured by gas-liquid chromatography.

Estrone-3-glucuronide (E1-3-G) and estriol-16α-glucuronide (E3-16-G) values, measured by direct RIA, closely paralleled the total urinary oestrogen measured fluorimetrically.

Ovarian response to ovulation induction therapy can be monitored by observing the changes in the levels of E1-3-G in urine. Pre-ovulatory levels of urinary E3-16-G were found to be too low for use in this regard.

Direct RIA for E1-3-G and Pd-3-G are recommended as reliable indices of ovarian function in the monitoring of patients receiving treatment for the induction of ovulation.
Affinity Chromatography of Amniotic Fluid Alphafetoprotein Using Concanavalin A-Sepharose
Authors: Noyes Jennifer A , Wood P J
Published: February 2014

We measured Concanavalin A (Con A) non-binding alphafetoprotein in amniotic fluid from 21 normal pregnancies and 20 abnormal pregnancies (complicated by anencephaly, spina bifida, or exomphalos) using small Con A-sepharose chromatography columns. There was a highly significant difference between percentage non-binding alphafetoprotein levels for pregnancies with a normal outcome (mean result 32%; range 18–47%) and pregnancies complicated by a neural tube defect or exomphalos (mean 14%; range 7–20%). The test is therefore of potential value in cases where there is uncertainty over the interpretation of total amniotic fluid alphafetoprotein levels.
Thyroxine Radioimmunoassay for Population Surveys Using Dried Blood: Modifications of a Highly Sensitive Method
Authors: Obregón María Jesús
Published: February 2014

A highly sensitive radioimmunoassay for the determination of thyroxine in blood spotted on filter paper is described. The radioimmunoassay developed by Weeke and Ørskov for determination of serum thyroxine was simplified and shortened, and its cost was decreased, for use in programmes for mass screening of thyroid function.

The method permits the use of small (2 mm diameter) dried blood dots, thus avoiding interference by binding proteins. Polyethylene glycol 6000 is used for the final separation of antibody bound labelled thyroxine, instead of the expensive and time-consuming wick chromatography used in the reference method. Serum thyroxine concentrations obtained using dried blood by the modified procedure correlate well with those obtained using serum by the reference method. The distribution of serum thyroxine concentration for a population of 2134 babies is given.
Heat Inactivation of Gamma-Glutamyltransferase in Homogenates of Human Kidney
Authors: Shakespeare Peter G , Stokes Susan H , Futerman Anthony H
Published: February 2014

The properties of γ-glutamyltransferase in homogenates of human kidney were investigated by measuring its susceptibility to inactivation by heating at 56°C. In freshly prepared homogenates, or after short storage at −20°C, the enzyme was observed to be relatively heat-stable. However, it could be transformed into a heat-labile form by treatment with thiol compounds or the proteolytic enzymes trypsin and papain. This process was not necessarily accompanied by solubilisation of the enzyme from the particulate fraction of the homogenate. The addition of 1 mmol/l glutathione during the heating step completely protected the enzyme against heat inactivation in either the relatively heat-stable form or the heat-labile form produced as a result of prior treatment with enzymes or thiol reagent. The observation that glutathione concentrations lower than the apparent Km for glutathione as a substrate fully protect the enzyme against heat inactivation suggests that the enzyme contains a second binding site for glutathione. This second site would be of higher affinity for glutathione than the substrate-binding site but would not itself participate in the enzyme reaction.
Enzyme-Linked Immunoadsorbent Assay for Serum IgE: Evaluation in Four Centres
Authors: Bienvenu J , Bienvenu F , Michaud-Caudie C , Quincy C , Nicolas J P , Phang Pho Phou , Mandrand B , Trabuc-Jaubert M
Published: February 2014

We report an evaluation of a commercially available kit, the Biomérieux IgE-kit, for determination of total IgE in serum by the EIA double antibody sandwich method. Results by this procedure and PRIST (Pharmacia) show a degree of association (r) of 0·98 and a regression equation of log y = 0·79 log PRIST+log 3·31. Correlation between the IgE kit and RIST shows a degree of association of 1·00 and a regression equation of log y = 1·01 log RIST—log 1·05. Between-laboratory standard deviations are 3%, 3%, and 15% for IgE concentrations of, respectively, 83, 285, and 900 IU/ml. Similarly, intra- and inter-assay correlations were performed on 60 lyophilised serum samples tested in the four centres. No protein interference was found except for cryoprecipitates. The favourable correlation with existing procedures and the feasibility of this kit offer a new way of measuring IgE levels.
Blood Dehydroascorbic Acid and Diabetes Mellitus in Human Beings
Authors: Banerjee Atasi
Published: February 2014

Ascorbic acid and dehydroascorbic acid were estimated in the blood of normal healthy subjects and diabetic patients. In normal subjects, blood contained only ascorbic acid while dehydroascorbic acid was practically absent. The ascorbic acid level was low in the blood of diabetic patients but the dehydroascorbic acid content was remarkably high, irrespective of age, sex, history of diabetes, or treatment. About 75% of blood dehydroascorbic acid was present in the erythrocytes: the rest was in plasma. High blood dehydroascorbic acid levels were also found in 90% of the non-diabetic offspring with both parents diabetic, in 24% of the non-diabetic offspring with one parent diabetic, and in 75% of the non-diabetic siblings of diabetic patients. It appears that, in persons having an hereditary predisposition to diabetes, high blood dehydroascorbic acid levels may be used as a marker for early detection of the disease.
Stability of Pancreatic Enzyme Activities in Duodenal Juice after Pancreatic Stimulation by a Test Meal or Exogenous Hormones
Authors: Muller D P R , Ghale G K
Published: February 2014

The activities of pancreatic lipase, pancreatic amylase, and trypsin were followed after storage at −20°C in duodenal juices collected after pancreatic stimulation by either a test meal or exogenous hormones. The activities of all three enzymes were stable for up to one year in juices collected after a test meal. However, in nine out of 10 hormonally stimulated juices, lipase activities fell to less than 50% of the initial activity within three weeks of storage, and in a third, trypsin activities fell to less than 60% over a similar period. Amylase activities remained relatively unchanged. The in-vitro addition of the test meal, its separate components, or glycerol (50%, v/v) stabilised lipase and trypsin activities in hormonally stimulated juices stored at −20°C for at least one month.
Paracetamol Estimation: A New Approach to Reducing Salicylate Interference
Authors: Barker Deirdre E , Jacobs Anthony G
Published: February 2014

It is now well established that although acetylsalicylate does not interfere with the commonly used nitration method for measuring paracetamol, salicylate does interfere. Several methods have been used to remove this interference, by solvent extraction, or to make allowance for the interference, for example, by arithmetical correction. We describe a new approach to the problem by modifying the reaction conditions in an attempt to find the optimum conditions for the nitration of paracetamol while at the same time minimising salicylate interference. A method is proposed in which the concentration of nitrite is reduced and a time delay is introduced after the addition of sulphamic acid. This method is shown to be accurate, precise, and linear and exhibits minimal interference from salicylate.
A Rapid High-Performance Liquid Chromatographic Method for Quantitation of 5-Fluorouracil in Plasma after Continuous Intravenous Infusion
Authors: Sampson D C , Fox R M , Tattersall M H N , Hensley W J
Published: February 2014

A fast, simple, precise, high-performance liquid chromatographic method for the assay of 5-fluorouracil in plasma from humans receiving continuous intravenous infusion is described. After a single extraction, underivatised 5-fluorouracil is assayed by high-performance liquid chromatography using a variable-wavelength ultraviolet detector. After extraction of 1 ml plasma, 0·3 μmol/l can be assayed. The assay is reproducible and linear up to at least 40 μmol/l. A single determination takes 3 hours and a batch of 40 specimens can be extracted and assayed in 4 working hours if automated equipment is used, enabling injections and calculations to be done overnight.
Salivary Cortisol Determination: Adaptation of a Commercial Serum Cortisol Kit
Authors: Al-Ansari A A K , Perry L A , Smith D S , Landon J
Published: February 2014

The determination of Cortisol levels in saliva offers a number of significant advantages as compared with plasma or serum measurements, and radioimmunoassay is the technique of choice because of the greater sensitivity required. To date, the assay of salivary Cortisol has been limited to only a few centres employing ‘in-house’ reagents. We describe some simple modifications of a commercial kit, designed for the assay of Cortisol in serum and urine, which allow direct and rapid determination of the steroid in saliva. These modifications enable any laboratory with access to a gamma counter to perform large numbers of salivary Cortisol assays at relatively low cost.
Effect of Recent Food on Estimation of High-Density Lipoprotein and Total Cholesterol in Normal Subjects
Authors: Booth S , Lacey R W
Published: February 2014

Magnesium/phosphotungstic acid was confirmed as specific for precipitation of chylomicrons, low-density and very low density lipoprotein particles in serum from healthy volunteers who were either fasting or who had eaten egg yolks or a salmon sandwich containing Flora margarine 2 hours previously.

In eight subjects who ate salmon sandwiches that contained butter or Flora margarine, neither the total cholesterol nor the high-density lipoprotein (HDL) cholesterol differed significantly from the fasting level over 7 hours. In eight subjects, egg yolks also did not alter significantly either the total serum cholesterol or the HDL cholesterol at ½, 1, 1½, 2, 5, and 7 hours after eating. Patients may be screened for HDL cholesterol and total cholesterol estimation when not fasting.

However, individual subjects showed variation in their total cholesterol and, particularly, HDL cholesterol over a three-month period. Replicate analysis of HDL cholesterol may be required for its complete assessment.
Automated and Manual Use of a Sensitive Reagent for the Determination of Chloride in Biological Fluids
Authors: Holder Peter E
Published: February 2014

An automated method is described for the determination of chloride in biological fluids using a mercuric 2,4,6-tri-(2-pyridyl)-1,3,5-triazine reagent. Results obtained by this method compared favourably with those obtained by coulometric titration. The same reagent was used manually to measure the small amounts of chloride in sweat. The results obtained agreed well with the direct measurement of chloride using an ion-specific electrode.
Biochemical Markers in Ovarian Cancer: Possibilities and Limitations
Authors: Haije W G
Published: February 2014

Cancer of the ovary is the commonest cause of death from gynaecological neoplasms. As ovarian tumours are relatively inaccessible, there is a great need for methods to improve early diagnosis and to assist with the management of patients with this disease. In this presentation the state of the art is discussed with regard to the usefulness of the presently recognised ‘tumour antigens’ and other biochemical markers in ovarian cancer.

Of the oncodevelopmental antigens, only alpha fetoprotein and chorionic gonadotropin are well established as good markers in tumours with, respectively, yolk sac and trophoblastic elements. Carcinoembryonic antigen seems from our own experience to be an unreliable marker in cancer of the ovary. In epithelial tumours, which constitute the majority of ovarian malignancies, mostly serous and mucinous cystadenocarcinomas, some tumour products have been described, which may have potential as a marker, for example, ovarian cancer associated antigens, some glycoprotein glycosyltransferases, and also carcinoplacental alkaline phosphatases (CPAP).

Recently, in patients with epithelial ovarian tumours attending our institute, multiple biochemical markers have been studied, including CPAP, phosphohexose isomerase, and some acute phase reactant proteins. The preliminary results, which will be discussed, show that longitudinal studies of some of these markers could have clinical application in follow-up.

It must be concluded that, in spite of all efforts so far, and although some markers may become useful, early detection of ovarian cancer is a goal still to be reached by clinical chemistry in the field of oncology.
Evaluation of Four Methods for the Direct Assay of Progesterone in Unextracted Serum
Authors: Ratcliffe Wendy A
Published: February 2014

The analytical performance of four radioimmunoassays for the determination of progesterone in unextracted serum is evaluated. The methods include kits from Radioassay Systems Laboratories (RSL), Nordiclab, Behringwerke, and an in-house assay. Extraction of progesterone from serum is avoided in these methods by employing various agents to displace progesterone from binding proteins. The radioimmunoassays employ 125I-labelled progesterone derivatives, and bound and free fractions are separated by double antibody, polyethylene glycol or charcoal methods. The in-house method gives essentially quantitative recovery of progesterone, and results of patients' specimens correlate well with those obtained by a reference method involving extraction of serum. The Nordiclab kit gives progressive under-recovery of progesterone with increasing progesterone concentration, and results of patients' specimens correlate poorly with those obtained by other methods. Gross over-recovery of progesterone is obtained with the RSL kit, and results of patients' specimens are approximately three-fold higher than those of the reference method. The Behringwerke kit is precise but biased, progesterone levels being over-estimated in both recovery pools and patients' specimens. The performance of these methods and their suitability for the assessment of luteal function are discussed.
Screening of Bacteria in Urine Using Luciferin-Luciferase Assay of Microbial ATP: A Comparative Study
Authors: Ruokonen Aimo , Koskinen Matti , Leinonen Maija , Tiilikainen Anja , Vihko Reijo
Published: February 2014

A total of 3227 urine specimens were analysed to investigate the applicability of a firefly luciferase assay of microbial adenosine triphosphate (ATP) for the rapid screening of bacteriuria in clinical specimens. Urine sediment, dipslide culture, and three plate cultures were also investigated in the majority of the urine specimens, the plate cultures serving as the reference. Of the specimens with positive plate culture (≥105 colony forming units (CFU)), leucocyte content of the spun urine sediment was negative (≤4 cells per high-power field) in 34% and bacterial content was negative in 14% (no bacteria seen microscopically); the dipslide test was negative (<105 CFU) in 16%, and the luminescence assay of ATP in 7% (≥ 500 relative light units). Of the urine specimens forming less than 105 CFU on plate cultures, leucocytes were positive in 15%, spun sediment bacteria in 21%, the dipslide test in 0 · 5%, and the luminescence assay of ATP in 11%. When used as a screening test for further studies by complete culture techniques, the luminescence assay of microbial ATP can improve the rapid diagnosis of urinary tract infections.
Use of Youden Plot for Internal Quality Control in the Immunoassay Laboratory
Authors: Jeffcoate S L
Published: February 2014

The Youden two-sample plot has been adapted for use in internal quality control in the immunoassay laboratory. It can be designed to show within-batch imprecision and drift as well as long-term between-batch reproducibility and is proposed as a method that is more economical and easily understood than other current plotting procedures.
A Rapid Procedure for the Simultaneous Estimation of the Anticonvulsant Drugs, Ethosuximide, Phenobarbitone, Phenytoin, and Carbamazepine in Serum Using High-Pressure Liquid Chromatography
Authors: Turnell David C , Trevor Susan C , Cooper John D H
Published: February 2014

A rapid isocratic high-pressure liquid chromatography procedure for the analysis of ethosuximide, phenobarbitone, phenytoin, and carbamazepine in serum is described. The method employs a single extraction from serum; alumina treatment of this extract eliminates interference from fast-eluting compounds, allowing rapid chromatography. A linear response is obtained for drug concentrations up to three times the upper limit of the therapeutic ranges. Within-batch and between-batch precisions for the means of these ranges varied from 2·2 to 5·5% and from 3·1 to 7·5%, respectively.
Comparison of Routine Analytical Methods in the Netherlands for Seven Serum Constituents Using Pattern Recognition
Authors: Jansen Rob T P
Published: February 2014

Routine analytical methods for seven serum analytes (calcium, chloride, cholesterol, glucose, inorganic phosphate, urate, and urea) are assessed using data from the Netherlands coupled external/internal quality control program. From the results of a trial each method can be described by four features: measures of bias, between-day precision, tendency to give erroneous results, interlaboratory variance. These four features of each trial determine a vectorpoint in the four-dimensional space for a particular method. From 12 trials a maximum of 12 vectorpoints per analytical method was obtained.

Pattern recognition techniques allowed the detection of clusters of vectorpoints.

Analytical methods having vectorpoints classified in different clusters perform differently. The mean feature values of the vectorpoints forming a cluster determine the quality of that cluster. A weighting procedure reveals the importance of the respective features for discriminating the clusters. For all of the seven analytes, clusters of vectorpoints were found. Different features appeared to contain discriminatory power for different analytes.

For six analytes (calcium, chloride, cholesterol, glucose, inorganic phosphate, and urea) an analytical method was found to classify predominantly in the qualitative best cluster.

One analytical method for the determination of chloride and one for glucose, inorganic phosphate, and urea did not cluster at all.
Diagnostic Value of Three Methods for Assessing Free Thyroxine in Pregnancy
Authors: Wilke T J
Published: February 2014

The clinical value of free thyroxine index, thyroxine/thyroxine binding globulin ratio, and free thyroxine concentration were compared in 46 pregnant patients. Overall the free thyroxine index was the best diagnostic index. Pregnancy induced changes in levels of free thyroxine and the thyroxine/thyroxine binding globulin ratio, which gave rise to interpretative problems in some pregnant subjects.
Three Families with Fast Bisalbuminaemia
Authors: Yakata Minoru , Sugita Osamu , Tomiyama Yae , Odani Shoji
Published: February 2014

We describe three cases of familial (SH, AY, and TM) fast-type bisalbuminaemia identified from 300 000 electrophoretic strips screened during the past six years. The immunological antigenicity and chemical composition of the isolated fast and normal albumins were essentially indistinguishable in all three cases. Detailed analyses on one of them (TM) by circular dichroism and fluorescent spectra measurements indicated that there was a marked change in the environment of the single tryptophan residue of the fast albumin, suggesting an alteration in the tertiary structure of the molecule. It is likely that this abnormality of the tertiary structure modulated (perturbed) the distribution of electric charges on the protein surface and thus changed its electrophoretic mobility.
Measurement of Serum Thyroxine by Solid-Phase Chemiluminescence Immunoassay
Authors: Weerasekera D A , Kim J B , Barnard G J , Collins W P
Published: February 2014

Descriptions are given of two solid-phase chemiluminescence immunoassays for the measurement of total thyroxine in serum. The antibodies were either attached to small uniform plastic microspheres (method 1) or passively adsorbed to antibody-coated tubes (method 2). The labelled antigen was thyroxine-aminobutyl ethyl isoluminol. After the antibody-binding reaction the antibody-bound fraction was washed, sodium hydroxide was added, and the mixture was incubated. Luminescence was initiated by oxidation of the label with microperoxidase/hydrogen peroxide and the signal integrated for 10 seconds. The light yield is inversely proportional to the concentration of thyroxine in the standard or sample. Both methods have similar sensitivity and precision to that obtained by a conventional radioimmunoassay.
Comparison of Bolton-Hunter and Chloramine-T Techniques for the Radioiodination of Prostatic Acid Phosphatase
Authors: Sturgeon C M , Beynon L , Seth J , Chisholm G D
Published: February 2014

A double antibody, semi-automated radioimmunoassay for serum prostatic acid phosphatase (PAP) is described, which uses the 125I-labelled N-succinimidyl-3-(4-hydroxyphenyl) propionate ester of PAP. This type of label has substantially higher immunoreactivity than that prepared using the chloramine-T method of radioiodination. Chromatographic purification of either label on Ultrogel ACA44 further improved immunoreactivity. The lowest detection limit (0·35 μg/l) was achieved with the chromatographically purified ester label.
A Potential Systematic Error in Using Lysivane as Inhibitor in the Measurement of Amniotic Fluid Acetylcholinesterase by the Ellman Method
Authors: Webb B A , Richardson S J , Garry R , Atkins J
Published: February 2014

The measurement of low levels of cholinesterase or acetylcholinesterase by the Ellman method requires correction for a non-enzymatic increase in absorption at 412 mμ that is due both to non-enzymatic hydrolysis of the acetylthiocholine substrate and to modification of the colour reagent. The rate of increase in absorption is dependent on temperature and pH. Addition of an acidic solution of lysivane to the assay solution for selective measurement of amniotic fluid acetylcholinesterase gives rise to a shift in pH; the use of methanol is suggested as an easier method of dissolving the inhibitor and does not affect the pH of the assay, obviating any need to redetermine the background absorption. There is, however, no improvement in ability of the method to predict pregnancies associated with neural-tube defects.
Use of a Recommended Evaluation Scheme in the Assessment of a New Digoxin Radioimmunoassay Kit
Authors: Gibb Ian
Published: February 2014

A new digoxin radioimmunoassay kit with a magnetisable solid-phase antibody was assessed using a recommended evaluation scheme. The kit was found to have acceptable performance characteristics, and the results are presented in the format recommended in the evaluation scheme to maximise comparability with data from other such studies. While the evaluation protocol was found to be generally workable and valid, modifications are suggested to enhance its applicability to an immunoassay system.
Variance Reduction in Analytical Processes in the Clinical Laboratory by Digital Filtering
Authors: Jansen R T P , Bonants P J M
Published: February 2014

A model is postulated describing the fluctuations in analytical chemical processes in the clinical laboratory. In this model the process variations are described by a non-stationary stochastic process with a significant time-varying mean value. Experiments demonstrate a short-term variance within a run and a long-term variance between runs determined by the time-varying mean value. For four different analytical systems used for determining six serum analytes between-run variance was demonstrated to be significantly greater than within-run variance. Based on the model a digital filtering procedure is presented which in each run estimates the process mean and subsequently corrects serum samples for its deviation. Thus significant variance reductions are obtained. The filtering procedure was tested for the determination in inorganic phosphate with a continuous-flow system in an experimental environment.
Analysis of External Quality Assessment Results in Three Dimensions
Authors: Karjalainen Erkki J , Karjalainen Ulla
Published: February 2014

During the last six years there has been a marked change in the nature of interlaboratory variance in enzyme determinations in Finland. With ordinary two-dimensional plotting methods the change is difficult to see, because enzyme activities are different for each control serum. The decrease in the coefficient of variation (CV) is best seen when the CV is displayed as a trend surface as a function of time and enzyme activity. While the overall variance has decreased, the shape of the curve relating CV to enzyme activity has also changed. The dependence of CV on the enzyme activity level has decreased slightly. The use of trend surfaces to describe three-dimensional functions in external quality assessment is described.
Potential Applications and Pitfalls of Dry Reagent Tests
Authors: Clark Penelope M S , Broughton P M G
Published: February 2014

In recent years, the development of dry reagent tests has made it possible for many clinical laboratory tests to be performed not only in the laboratory but also elsewhere. Some of the factors influencing the applications and use of one such system, the Ames Seralyzer, have been studied. Sample volume and the timing of analysis were critical, and poor precision was obtained by an inexperienced operator. The calibrators and reagent strips were stable when stored as recommended by the manufacturer, and calibration was stable for 24 hours. The implications of these findings as well as the problems of method comparison and quality control are discussed, particularly in relation to the use of the instrument outside the laboratory. More generally, this study illustrates several problems with the use of dry reagent, thin films and associated instrumentation that must be considered during evaluations.
A Simple and Economical Method for the Preparation of Adsorbents for the Thyroid Hormone Uptake Test
Authors: Al-Awqati M A , Al-Oneizi O S M , Nasralla M , Sinlao Digna , Al-Ansari A K , Hassan Mithal
Published: February 2014

A low-cost and simple method has been developed for the preparation of human or animal protein-based adsorbents for use in the thyroid hormone uptake test. A combination of sodium sulphate precipitation and glutaraldehyde polymerisation of pooled whole serum or purified albumin preparations was employed to yield a fine solid-phase suspension which eliminates the need for capping and rotating assay tubes. Results for 107 samples obtained by this method correlated well with those obtained by use of a commercial kit.
An ELISA for Pregnancy-Associated Plasma Protein A
Authors: Pledger D R , Belfield A
Published: February 2014

An enzyme-linked immunoassay for pregnancy-associated plasma protein A is described. The assay is sensitive (7·6 IU/1) and precise (overall CV varied between 8·9% and 10·8%). Recovery was 100% over the working range. Parallel behaviour was observed between the International Reference Preparation 78/610 and pregnancy serum, thus allowing calibration of a laboratory standard pool against IRP 78/610.
A Reappraisal of the γ-Glutamylcysteine Synthetase Activity in Haemolysates from Normal Erythrocytes by Two Different Methods
Authors: Lestas A N , White J M
Published: February 2014

γ-Glutamylcysteine synthetase catalyses the combination of l-glutamate and l-cysteine to form γ-glutamylcysteine with a stoichiometric conversion of ATP to ADP and inorganic phosphate (Pi). During the estimation of this enzyme in haemolysates from normal erythrocytes it was found that the Pi released was more than the amount of γ-glutamylcysteine synthesised. Furthermore, the activity estimated by analysing either product was higher than the corresponding values reported in the literature. An investigation into these discrepancies resulted in improvements of the assay methods which produced two substantially different normal ranges for the γ-glutamylcysteine synthetase activity in haemolysates: one derived from the Pi released and the other from the γ-glutamylcysteine synthesised during the enzymatic reaction.
A Comparison of Two Methods for the Determination of Thallium in Urine
Authors: Bessems G J H , Westerhuis L W , Baadenhuijsen H
Published: February 2014

Two analytical procedures for the determination of thallium in urine are evaluated and compared. The two methods consist of differential pulse anodic stripping voltammetry and flameless atomic absorption spectrophotometry. Both procedures correlated well and were found to be acceptable in terms of precision and analytical recovery. However, a solvent extraction step proved to be necessary for the AAS procedure, and the linearity with respect to the concentration range was rather limited. The method based on DPASV is simple, accurate, precise, and sensitive and does not require any pretreatment of the sample. We therefore recommend the voltammetric procedure for the determination of thallium in urine, as described in this paper.