Radioimmunoassay Technology Research Articles

Effect of Radioimmunoassay on Accuracy of Thyroid Hormone Detection.

At present, the most important method for the detection of thyroid hormones in hospitals in China is radioimmunoassay. Besides radioimmunoassay, there are blood test and antibody test methods for thyroid hormone detection. However, after long-term clinical investigations, the accuracy of the results of thyroid hormone detection by radioimmunoassay has been affected by many factors. Possible influencing factors include inaccurate thyroid hormone test results due to improper way of blood collection by nurses and improper way of keeping and transporting blood samples by nurses. Therefore, this paper analyzes and discusses the influencing factors of the accuracy of thyroid hormone (T4) detection by radioimmunoassay technology. In this paper, we conducted research using statistical analysis of clinical data, improved separation methods for quality control in the laboratory, and blood specimen collection methods. Radioimmunoassay occurs with antibodies. Of the 10 batches of 964 cases in the improved separation methods for quality control in the laboratory, 154 mismatched items accounted for 16%, and the error of method and operation only accounted for 5.8% of unmatched specimens, most of which were the biochemical characteristics and clinical manifestations of thyroid hormones. The blood sample collection method research found that mild hemolysis had no significant effect on the measurement results, severe hemolysis had a tendency to affect the results, and blood collection tubes had no effect on the test results. Mild hemolysis refers to the increase in the rate of red blood cell destruction due to various internal and external factors in the body. The symptoms when mild hemolysis occurs are generally not obvious. Severe hemolysis refers to a disease caused by blood group incompatibility, mainly referring to immune hemolysis caused by blood group incompatibility between mother and baby, as well as severe jaundice or severe anemia. The statistical analysis of clinical data found that, among 160 patients, the reasons for the inaccuracy of T4 results using radioimmunoassay technology were as follows: 104 patients were inaccurate due to personal factors, and the results were due to hospital factors. A total of 56 patients had inaccurate results. During the measurement of thyroid hormone, it will be affected by many factors. For this reason, the influencing factors of the accuracy of radioimmunoassay should be clarified, and appropriate measures should be taken to deal with it, so as to give full play to the role of radioimmunoassay and improve the detection.

In vitro evaluation of concentration, labeling effectiveness and stability for 131 I-labeled radioimmunoassay ligand using real-time detection technology.

Radioimmunoassay belongs to the analytical method enabling highly specific and sensitive quantification of molecules. The verification of the real-time radioimmunoassay technology usefulness for ligand-quality characteristics evaluation such as concentration, influence of radiolabeling on binding affinity and stability was estimated. The anti-epidermal growth factor receptor antibody 131 I-cetuximab was employed as the ligand antibody. The concentration of 131 I-cetuximab was derived from the shape of binding curves coming from the ligand-receptor interaction. The binding curves also allowed the estimation of 131 I-cetuximab binding affinity for different radiolabeling procedures (incubation times 1, 5, and 10minutes) in stability testing up to 96hours at 4°C. The stability testing also included comparative analysis by size exclusion high-performance liquid chromatography. The assessment of cetuximab concentrations using real-time method showed acceptable accordance between real and calculated values. The real-time method revealed that 1-minute radiolabeling proved to be the optimal incubation time for direct radioiodination of cetuximab. Stability testing showed the significant change in radioligand affinity by one order at the longest incubation times (72 and 96hours). Characterization of stability and binding behavior of radiolabeled monoclonal antibodies by the verified real-time method before use in other assays may be employed to eliminate variability and suboptimal antibody performance.

A 25-Year Experience of Gastroenteropancreatic Neuroendocrine Tumors and Somatostatin (Congeners) Analogs: From Symptom Control to Antineoplastic Therapy.

Radioimmunoassay technology was utilized in the discovery of somatostatin and was quickly brought into therapeutics; however, it took the development of somatostatin congeners to solve its limitations of a short half-life. Therapeutic medical control of hyperhormonal states such as acromegaly, carcinoid syndrome and VIPoma significantly advanced from a nonspecific approach to one that specifically and effectively targeted the underlying pathophysiology. Clinical care was transformed from nonspecific symptom control to one of a significant improvement in not only quality of life, but also quantity of life. These data submitted to US and European regulatory authorities for approval included many investigative sites with no uniform protocol and multiple investigational new drugs, and have not been previously published. This review includes the original data demonstrating the transformational impact this class of agents had on specific disease subsets resulting in regulatory approval 25 years ago. Autoradiography techniques using somatostatin resulted in identifying, localizing and characterizing its receptor subtypes. Translating in vitro data to in vivo resulted in scintigraphic whole body and SPECT scans with (111)In-pentetreotide and was incorporated into standard clinical care 20 years ago. (68)Ga-octreotide congeners using PET scanning offers a major imaging advance. Peptide receptor radiotherapy has evolved over the last 2 decades and utilizes several therapeutic isotopes, including (90)Y and (177)Lu.

Melanin concentrating hormone in central hypersomnia

Narcolepsy with cataplexy (NC) is a disabling disorder characterized by excessive daytime sleepiness and abnormal rapid eye movement (REM) sleep manifestations, due to a deficient hypocretin/orexin neurotransmission. Melanin concentrating hormone (MCH) neurons involved in the homeostatic regulation of REM sleep are intact. We hypothesized that an increased release of MCH in NC would be partly responsible for the abnormal REM sleep manifestations. Twenty-two untreated patients affected with central hypersomnia were included: 14 NC, six idiopathic hypersomnia with long sleep time, and two post-traumatic hypersomnia. Fourteen neurological patients without any sleep disorders were included as controls. Using radioimmunoassays, we measured hypocretin-1 and MCH levels in cerebrospinal fluid (CSF). The MCH level was slightly but significantly lower in patients with hypersomnia (98 ± 32 pg/ml) compared to controls (118 ± 20 pg/ml). After exclusion of patients affected with post-traumatic hypersomnia the difference became non-significant. We also failed to find any association between MCH level and hypocretin level, the severity of daytime sleepiness, the number of SOREMPs, the frequency of cataplexy, and the presence of hypnagogic hallucinations or sleep paralysis. This study reports the first measurement of MCH in CSF using radioimmunoassay technology. It appears to be a non-informative tool to differentiate etiologies of central hypersomnia with or without REM sleep dysregulation.

Ameliorative Effect of Captopril and Valsartan on an Animal Model of Diabetic Cardiomyopathy

The objective of this study was to clarify the relationship between angiotensin II and the pathogenesis of diabetic cardiomyopathy by observing the effects of related drugs on diabetic cardiomyopathy in rats. Captopril and Valsartan, an automatic biochemical analyzer, and radioimmunoassay technology were used to an experimental rat model of diabetic cardiomyopathy to dynamically measure the levels of creatine kinase-MB, lactate dehydrogenase-1 in the serum, and angiotensin I and II in the plasma, and to observe changes in the myocardial ultrastructure. The content of angiotensin I and II was increased and the renin-angiotensin system was in a hyperfunctional state in experimental rats with myocardial damage. Angiotensin-converting enzyme inhibitors and angiotensin II receptor 1 antagonists improved the myocardial structure and cardiac function. It is concluded that hyperfunction of the renin-angiotensin system is involved in the pathogenesis of diabetic cardiomyopathy, with an increase in angiotensin being a key factor. Preventing the increase in angiotensin II or the action of angiotensin II on its receptor can prevent the occurrence and development of diabetic cardiomyopathy.

Effects of alcohol consumption on eight circulating markers of liver fibrosis.

A number of circulating breakdown products of collagen or other components of extracellular matrix, matrix degrading metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) have been proposed as markers of hepatic fibrosis. However, the published results lack consistency. Since many of the patients with fibrosis studied were alcoholics, the question was raised whether recent alcohol consumption may affect the results obtained. Using sandwich-type assays of radioimmunoassay technology with corresponding antibodies, we studied eight markers of liver fibrosis: laminin, tenascin, undulin, TIMP-1, collagen VI, procollagen type III (PIIINP), hyaluronic acid (HA) and MMP-2. A group of 10 alcoholics was studied after significant alcohol consumption and following 2 weeks of abstinence, verified with repeated breath alcohol measurement. Laminin was significantly reduced at 1 week (22%) and at 2 weeks (30%). Similarly, tenascin and undulin were also significantly decreased. By contrast, TIMP-1, collagen VI, PIIINP, HA and MMP-2 did not significantly change. The mode of action of alcohol on these tests is unknown. These differences must be considered when using those measurements to assess liver fibrosis.

Development and Proliferation of Radioimmunoassay Technology

Radioimmunoassay (RIA) developed as a fallout from investigations concerning the nature of maturity-onset diabetes. We studied the metabolism of 131I-labeled insulin in nondiabetic and diabetic subjects to determine whether rapid insulin metabolism was responsible for Type 2 diabetes. Unexpectedly, we observed that radioactive insulin disappeared more slowly from the plasma of patients who had received insulin than from the plasma of subjects never treated with insulin. While immunologists of the mid-1950s did not believe that a 6,000-dalton peptide could be immunogenic, we found that the retarded rate of insulin disappearance was due to binding of labeled insulin to insulin-binding antibodies. This first use of radioisotopic methods for detection of soluble antigen-antibody complexes introduced a revolution in theoretical immunology. It is now appreciated that very small peptides can be antigenic and that the equilibrium constants for antigen-antibody reactions can be as great as 1014 liters per mole, a value up to 108 times greater than predicted by Pauling's theory of 1940. The RIA for insulin was developed when we realized that the concentration of insulin in a solution could be determined by comparing its inhibitory effect on the binding of radioactive insulin to antibody with the inhibitory effect of known insulin standards. Our initial observations with insulin suggested that antigenicity was a more general property than had been appreciated, and since non-antibody materials with specific binding characteristics were also available, RIA and related techniques quickly proliferated for the detection and measurement of a vast array of substances in our own laboratory and around the world.

15] Assay of 1,25-dihydroxyvitamin D3 from serum samples: Use of receptor-binding or enzyme-coupled reporter analysis

The measurement of 1,25-dihydroxyvitamin D 3 [1,25-(OH) 2 D 3 ] in biological samples is of great importance from a medical point of view and as a research tool. An assessment of serum 1,25-(OH) 2 D 3 concentration can be helpful in the diagnosis and treatment of a variety of bone diseases—parathyroid gland dysfunction, malignancies, renal failure, end-organ resistance diseases, and metabolic disorders. It is useful as a research tool in medicine, physiology, and metabolism. Traditional methodologies for 1,25-(OH) 2 D 3 measurement include bioassay, radioimmunoassay, cytoreceptor assay, or radioreceptor assay. Methods for serum metabolite isolation and preparation of stable 1,25-(OH) 2 D 3 receptor (VDR) have greatly improved the use of radioreceptor technology. Also, there have been improvements in radioimmunoassay technology for 1,25-(OH) 2 D 3 . Each of these methods has played a valuable role in the characterization of the disorders, however, they rely on complicated preassay strategies to isolate and purify 1,25-(OH) 2 D 3 . Advances in the development of monoclonal antibodies (mAb) to VDR and gene reporter systems for the assessment of 1,25-(OH) 2 D 3 action can be utilized as powerful tools for rapid, accurate, and sensitive measurements of 1,25-(OH) 2 D 3 . This chapter describes two of the newer approaches for determining 1,25-(OH) 2 D 3 concentrations from small volumes of serum. Neither of these assays requires extensive extraction, bound/free protein separation, or high-performance liquid chromatography because of the highly specific nature of each assay.

Recent advances in radioimmunoassay technology for the juvenile hormones.

Recent refinements in juvenile hormone radioimmunoassay technology now make this method significantly more sensitive and easier to use. Rabbit polyclonal antisera against (10R) JH III and racemic JH II have been developed to determine hemolymph hormone titers in the low picogram range. The antisera display minimal cross-reactivity with JH metabolites, JH analogs, and hemolymph lipids. One antiserum recognizes racemic JH I, II, and (10R) III almost equivalently, exhibiting 50% displacement between 100 and 130 pg per tube. Another antiserum is JH II-specific and exhibits 50% displacement at 35 pg per tube. Assay sensitivity has been enhanced by using (10R,11S) [methyl-3H]-JH II of very high specific activity (> 80 Ci/mmol) generated with Hyalophora cecropia accessory gland S-adenosylmethionine transferase and S-[methyl-3H]-adenosyl-L-methionine. Preparation of biological samples has been simplified with overall recoveries of JH from hemolymph ranging between 60 and 75%.

431 ELEVATED TESTOSTERONE (T) LEVELS IN A NEWBORN WITH 3-BETA-HYDROXYSTEROID DEHYDROGENASE (3 β-HSD) DEFICIENCY

The lack of virilization in newborn males with 3β -HSD deficiency has been attributed to their inability to synthesize Δ 4 steroids, particularly T. However, no steroidal studies using radioimmunoassay technology have been performed in the newborn with this disorder. A newborn male with pseudovaginal perineoscrotal hypospadias was found to have a serum 17 hydroxyprogesterone (17 OH P) level of 11,000 ng/dl and a T concentration of 1,095 ng/dl. The serum 17-hydroxypregnenolone concentration was 21,200 ng/dl and urine steroid determinations revealed a predominance of 16-alpha- Δ5-hydroxysteroids, with a Δ5 to Δ4 steroid ratio of greater than 1, confirming the presence of 3 β-HSD deficiency. Tetrahydro-E, the major urinary cortisol metabolite, was virtually absent. Although the initial serum T concentration was markedly elevated, HCG stimulation revealed a blunted T response with a stimulated Δ5-androstenediol to T ratio of 5 to 1. The markedly elevated Δ 4 steroids, including T, probably resulted from in utero conversion of Δ5 steroids by hepatic 3β -HSD activity. Although hepatic T production resulted in elevated serum T concentrations, the lack of urethral fold fusion in this infant can be explained by the relatively late onset of hepatic enzyme activity when urethral fold fusion can no longer be induced. These findings suggest that Δ4 steroids, particularly T and 17 OH P, are elevated in infants with 3 β-HSD deficiency. Although 17 OH P determinations may serve as a screening test for congenital adrenal hyperplasia, further evaluation is needed to confirm the specific enzyme defect.

Distribution of Cyclic Nucleotides in the Organ of Corti

Recent developments in radioimmunoassay technology have made possible measurements of cyclic nucleotides in individual specimens of the organ of Corti and its subdivisions. Steep longitudinal and transverse gradients of glycogen are known to exist in the organ of Corti of the guinea pig, with preferential accumulation in the outer hair cells of the apical turns. However, no significant longitudinal gradient of cyclic AMP was detectable in the organ of Corti, and the concentration of the compound was found to be nearly equal in the inner and outer hair cell layers. This is indirect evidence against the concept that cyclic AMP plays a role as "second messenger" in the control of glycogen metabolism of the organ of Corti. By contrast, the concentration of cyclic GMP was found to be consistently higher in the inner layer than in the outer layer of the organ of Corti, and to increase significantly in basal direction. This trend is remarkably similar to the distribution patterns of acetylcholinesterase, which may be considered as indirect evidence in favor of a possible role of cyclic GMP in the mediation of cholinergic effects.