Bioanalytical methods applied to endocrine disrupting polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans. A review

The usual methods for determining polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF) and polychlorinated biphenyls (PCB) are generally expensive and time consuming. This fact has favored the development of faster and cheaper techniques, based on immunoassays and bioassays. This paper reviews these bioanalytical methods and their analytical importance at the present moment.     

Octapeptide-Specific and Sensitive Assay for Angiotensin II in Plasma

Abstract

Angiotensin-(1–8)octapeptide (angiotensin II) is the active principle of the reninangiotensin system. Crossreaction of angiotensin II-antisera with inactive precursors and metabolic fragments prevented the specific quantitation of this hormone in biological fluids. Peptide-extraction on bonded-phase silica followed by peptide-separation using isocratic reverse-phase high performance liquid chromatography and subsequent radioimmunoassay rendered possible the octapeptide-specific measurement of angiotensin II in 2 ml plasma with a detection limit of 0.4fmol/ml. The coefficient of variation for intra-assay precision was 0.06 and for inter-assay precision 0.13. ¹²⁵Iangiotensin II was recovered from plasma by solid-phase extraction to 99±2% (mean ± S.D.). The overall recovery of 5, 10 and 20 fmol unlabeled angiotensin II added to plasma was 80±10%. Plasma concentrations in supine normal humans averaged 4.1 ± 1.6 fmol/ml and were suppressed below the detection limit by angiotensin I converting enzyme inhibition.     

Radioimmunologische Bestimmung von Pflanzenhormonen

In vorliegender Arbeit wird eine kurze Darstellung der Grundlagen, Erfordernisse, Vor- und Nachteile des Radioimmunoassay für Pflanzenhormone gegeben.

The purpose of this paper is to discuss briefly the basis, requirements, advantages, and disadvantages of radioimmunoassay with respect to plant hormones.     

An overview of analytical methodologies for the determination of antibiotics in environmental waters

The widespread occurrence of antibiotics as contaminants in the aquatic environment has increased attention in the last years. The concern over the release of antibiotics into the environment is related primarily to the potential for the development of antimicrobial resistance among microorganisms. This article presents an overview of analytical methodologies for the determination of quinolone (Qs) and fluoroquinolone (FQs), macrolide (MLs), tetracycline (TCs), sulfonamide (SAs) antibiotics and trimethoprim (TMP) in different environmental waters. The analysis of these antibiotics has usually been carried out by high-performance liquid chromatography (HPLC) coupled to mass spectrometry (MS) or tandem mass spectrometry (MS/MS) and to a lesser extent by ultraviolet (UV) or fluorescence detection (FD). A very important step before LC analysis is sample preparation and extraction leading to elimination of interferences and prevention of matrix effect and preconcentration of target analytes.     

CORRELATION OF ANNUAL CHANGE OF LUTEINIZING HORMONE-RELEASING HORMONE (LH-RH) WITH GONADAL DEVELOPMENT IN AMPHIOXUS

The present study demonstrates for the first time by RIA that LH-RH is present in the heads as well as the bodies of the amphioxuses of both sexes. Gonadoliberin increases gradually during the course of gonadal development. At the time of gonadal maturity, LH-RH content reaches a maximum. The annual change of LH-RH correlates well with gonadal development and the gonadosomatic index (GSI). The reproductive season of the amphioxus covers about three months from May to July, and LH-RH content starts to increase in May (66.89±5.26 ng) and reaches the peak in June (158.57±3.17 ng), indicating that LH-RH is likely also to be involved in the reproductive activity of the chordate. This finding is of significance in understanding the evolutionary process of the reproductive endocrine in the vertebrate.     

Direct Radioimmunoassay of Proinsulin and Insulin in Human Plasma by Chromatographic Technique

Specific method for direct radioimmunoassay of IRP and IRI separately in human plasma has been described. The method is used for extraction of total insulin and separation of IRP from IRI by paper chromatography to be assayed separately. The separation of the two components are indentified and confirmed by column chromatography, paper chromatography and U.V. spectral analysis in comparison with the standard compounds.

134 plasma samples of different cases were, investigated for determination of IRI, IRP and IRT, of which 39 normals, 16 normal obes, 21 juvinil diabetes, 18 adult oncet diabetes, 10 recent adult diabetes, 12 hypothroid and 18 bilharzial hepatosplenomegaly to evaluate the levels of the test in comparison with blood sugar concentration.     

Study of blood collection and sample preparation for analysis of vitamin D and its metabolites by liquid chromatography–tandem mass spectrometry

The analysis of vitamin D status, with special emphasis on 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D, is gaining interest in clinical studies due to the classical and non-classical effects attributed to this prohormone. In this research, the influence of the two steps preceding determination (viz. sample collection and preparation) on the quantitative analysis of vitamin D and its more important metabolites has been studied. Two preparation approaches, deproteination and solid-phase extraction (SPE), have been evaluated in terms of sensitivity to delimit their application, thus establishing that detection of 1,25-dihydroxyvitamin D cannot be addressed by protein precipitation. Concerning sample collection, serum and plasma reported high accuracy (above 83.3%) for vitamin D and metabolites, while precision, expressed as relative standard deviation, was below 12.9% for all analytes in both samples. Statistical analysis revealed that serum and plasma provided similar physiological levels for vitamin D₃, 24,25-dihydroxyvitamin D₃ and 25-hydroxyvitamin D₃, while significantly different levels were obtained for 1,25-dihydroxyvitamin D₃, always higher in plasma than in serum. Sample collection and treatment have proved to be significant in the analysis of vitamin D and its relevant metabolites.     

Chromatographic Purification of Tritiated Steroids Prior to Use in Radioimmunoassay

Abstract

The purity of tritiated steroids used as reagents in radio immunoassay plays an important role in the reliability of the assay. These radioactive reagents should be assessed for purity upon receipt and the purity should be checked periodically afterward. For such purposes, we have used chromatographic purification on Celite microcolumns. By charging the polarity of the stationary and mobile phases, 20 different tritiated steroids with a wide range of polarity could be purified on these microcolumns. This approach is easy, rapid, economical, and reliable.     

A Method to Assess Radiochemical Purity of Compounds Measured by Radioimmunoassay

Abstract

A method is described for assessing radiochemical purity of compounds measured by radioimmunoassay. This method is applicable in cases when chromatography is used prior to the radioimmunoassay proper. In individual fractions of the chromatographic zone containing the compound assayed, both radioactivity (e. g. in DPM) and mass (e. g. in pg) are measured. The measurement of mass is performed using radioimmunoassay. Radiochemical purity is assumed, if the radioactivity/mass ratio (specific activity) in individual fractions of the zone is constant. The constancy of specific activity is tested statistically using a regression analysis. A radioimmunoassay of progesterone in a blood plasma pool collected during the follicular phase of the menstrual cycle was used to demonstrate the practical features of the assessment of radiochemical purity. Radiochemical pure progesterone could be obtained only after repeated chromatography. Purification to radiochemical purity resulted in a significantly decreased estimate of progesterone contents in the plasma pool investigated. A value of 344 pg/ml was obtained, in contrast to the value of 422 pg/ml found prior to the repeated chromatography. The former value can be considered an accurate and valid estimate.     

活性小分子的辐射效应

研究结果表明:1.600R 注 X 线照射后,小白鼠肝中谷胱甘肽(GSH)浓度下降50％(P<0.01)、脾中增高36％(P<0.05)、肾中下降15.9％(P<0.05).2.当小白鼠照射前注射 GSH 或半胱氨酸(CySH)能稳定 SH 基水平.3.采用放射免疫技术(RIA)测定小白鼠血清胰岛素浓度,照射后16小时降低22.5％.血糖浓度照射后18小时下降9％.血清环化腺苷单磷酸(cAMP)浓度照后16小时下降31％.4.不同剂量γ线照射后,鼠脑含磷化合物的合成受到强烈抑制.5.6000R γ线照射后兔的通透屏障受到明显影响.