A rapid micromethod for prenatal diagnosis of Lesch Nyhan syndrome

A method is described which enables prenatal diagnosis of Lesch Nyhan Syndrome (HGPRT deficiency) to be made within 7-10 days. The procedure is based on the direct cultivation of amniotic cells in microtest II plates; the HGPRT reaction is performed in individual wells containing between 500 to 10,000 cells, and is followed by separation of the radioactive reaction products by means of microchromatography on 3 cm x 5 cm PEI plates. This method permits determination of the actual HGPRT enzyme activity of the cell lines.     

脑卒中患者血清心肌酶谱、血糖检测的意义

临床上治疗脑卒中同时应动态观察心肌酶谱及血糖变化,一旦出现心肌损害现象应及时调整治疗方案,保护心脏功能以防止永久性心肌损害的发生.     

A rapid micromethod for measuring theophylline in serum by reverse-phase high-performance liquid chromatography

We describe an assay system for measuring theophylline in 25 microliters of serum. The procedure involves extraction with a 95:5 mixture of chloroform:isopropanol containing beta-hydroxypropyltheophylline as internal standard, and reverse-phase chromatography on a 4 mm x 30 cm column containing "micron Bondapak C18." Theophylline and beta-hydroxypropyltheophylline are eluted with a 90:10 mixture of sodium acetate butter (20 mmoles/litre pH 4.0) and acetonitrile at a flow rate of 1.8 ml/min., are detected by their absorbance at 254 nm, and quantitated by measuring peak areas. Column temperature has not been found to be critical in this analysis. Each analysis requires 9 minutes of chromatography time with a total analysis time of 20 minutes. Analytical recoveries were found to be 71 to 75% for theophylline and 94% for beta-hydroxypropyltheophylline. This difference in recovery is corrected when determining the theophylline concentration in unknown samples. The method has good precision (coefficients of variation between 7.0% and 7.9% for therapeutic and toxic concentrations). The results obtained with this method compare favourably with results obtained by a published cation-exchange high-performance liquid chromatographic method. None of the metabolites of theophylline, common compounds related to theophylline in structure or drugs tested have been found to interfere with the analysis described.     

Phagocytosis of human blood leukocytes: a simple micromethod

A simple micromethod for testing human blood leukocyte phagocytosis employing synthetic hydrophilic particles based on 2-hydroxyethylmethacrylate is described. The normal level of phagocytosing leukocytes in healthy children was 20.1 +/- 2.7%, and in healthy adult donors 34.3 +/- 6.1%. The method was found suitable for routine testing in both clinical and laboratory practice.     

2d-generation Technicon Autoanalyzer: determination of blood sugar without dialysis and predilution of the sample

It's presented a simple modification of the method GOD/PERID in the automatized determination of glycemia. This modification excludes dialysis and introduces the prediluition of the specimen before the reacting mass. Experiments have been carried out with a sperimental manifold and with the reagents Glucosio Test and Glu-cinet Sclavo. From the results it comes out that the essential characteristics of the method are: a) a good precision and ripetition of the results; b) the possibility of using both biological and chemical standards to calibrate the instruments without alterating the results; c) a smaller use of reagents due to the use of small quantities of reagents.     

Separation-free electrochemical immunosensor for rapid determination of atrazine

A separation-free electrochemical immunoassay method for the detection of the pesticide atrazine is described. The method developed is a competitive ELISA incorporating disposable screen printed horseradish peroxidase modified electrodes as the detector element in conjunction with single-use atrazine immuno-membranes. Screen printed carbon electrodes were prepared using carbon ink incorporating horseradish peroxidase. A monoclonal antibody for atrazine was immobilised onto Biodyne C membranes which were, in turn, placed over the electrode surface. The assay was based on competition for available binding sites between free atrazine and an atrazine-glucose oxidase conjugate prepared 'in-house'. In the presence of glucose, H2O2 formed by the conjugate was reduced by enzyme-channelling via the HRP electrode. The HRP was in turn re-reduced by a direct electron transfer mechanism at a potential of +50 mV Vs Ag/AgCl. Any H2O2 formed in the bulk solution by unbound atrazine-GOD conjugate was scavenged by excess catalase thus removing the requirement for a washing step. The performance of the method was compared with a commercial immunoassay kit for atrazine.     

Validation of an automated microplate enzyme immunoassay for screening of postmortem blood for drugs of abuse

The objective of this study was to compare the sensitivity and specificity of an enzyme immunoassay employing antibodies bound to a microtiter plate (MPEIA) with those of two radioimmunoassays for screening postmortem blood from selected coroner's cases for drugs of abuse. The radioimmunoassays were a coated-tube radioimmunoassay (CTRIA) and a double antibody radioimmunoassay (DARIA). Specimens consisted of 260 postmortem blood specimens from coroner's cases. Immunoassay results (positive or negative) were compared with confirmed results on those cases by gas chromatography-mass spectrometry, alone or in combination with gas-liquid chromatography using either a nitrogen-phosphorus or flame-ionization detector. Sensitivity was calculated as the true-positive rate using chromatographic confirmation as the reference standard. Specificity was calculated as the true-negative rate. Sensitivity and specificity were calculated for 5-7 potential cutoff concentrations for the drug classes opiates, amphetamines, cocaine and metabolites, and barbiturates. For opiates, the sensitivity and specificity were 99% and 93%, respectively, for the MPEIA at a cutoff of 20-ng/mL morphine, compared with 94% and 96% for the CTRIA at a cutoff of 5-ng/mL morphine and > 99% and 96% for the DARIA at 20-ng/mL morphine. For cocaine and metabolites, the sensitivity and specificity were 96% and 93%, respectively, for the MPEIA at 50-ng/mL benzoylecgonine, compared with 93% and 96% for CTRIA at 50-ng/mL benzoylecgonine and 98% and 97% for the DARIA at 50-ng/mL benzoylecgonine. For amphetamines, the sensitivity and specificity were >99% and 91%, respectively, for the MPEIA at 25-ng/mL methamphetamine, compared with 93% and 86% for the CTRIA at 25-ng/mL methamphetamine and 83% and 89% for the DARIA at 50-ng/mL methamphetamine. For barbiturates, the sensitivity and specificity were > 99% and 92%, respectively, for the MPEIA at 50-ng/mL secobarbital, compared with 91% and 87% for the CTRIA at 500-ng/mL secobarbital and 79% and 95% for the DARIA at a cutoff of 1000-ng/mL phenobarbital.     

A rapid method for dry weight determination of proteins on a micro scale with an electrobalance

A method to determine the dry weight (0.25-2 mg) of aqueous protein solutions within 1 h, using an electrobalance, is described. The drying of 50-200 mul solution pipetted onto a glass fiber disc is carried out in vacuo at 70 degrees C until the recorded dry weight becomes constant (within 25-40 min). It has been shown that the dried residue can subsequently be used for other purposes, such as quantitative amino acid analyses. The method is also suitable for the determination of moisture content in lyophilized protein samples.     

Evaluation of an enzyme linked immunosorbent assay (ELISA) for determination of insulin in dogs

Between 1970 and 1983, 345 patients with ovarian cancer clinical stage I, II, and III were irradiated postoperatively. Five-year NED survival was achieved in 41.7% of patients. The most important prognostic factors were histological grade and clinical stage of cancer. Postoperative external beam radiotherapy appeared to be highly efficient for the patients with microscopic residual disease, giving 70% 5-year survival, and moderately efficient for patients with small, i.e. < or = 3 cm in diameter residual disease, giving 40% 5-year survival. The optimal technique of irradiation appeared to be the irradiation given to the entire abdominal cavity with additional irradiation coned down to the pelvis. External beam radiotherapy was ineffective in patients with gross residual disease, i.e. > 3 cm in diameter, and useless as palliative treatment given to patients with inoperable cancer of the ovary.     

An enzyme reactor electrode for determination of amino acids

Globin biosynthesis was studied in both erythroid precursors and reticulocytes of three individuals with heterozygous alpha-thalassaemia. In contrast to the finding of equal or nearly equal alpha and beta chain synthesis in the marrow of patients with heterozygous beta-thalassaemia previously examined, our studies showed equal degrees of unbalanced globin synthesis in both reticulocytes and nucleated-erythroid cells of alpha-thalassaemia heterozygotes. Greater stability and less susceptibility to proteolysis of the excess beta-chain formed in alpha-thalassaemia may explain our findings.