Antibodies against calcitonins as a source of analytical errors.
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Animals↗
Biomedical subjects
S Ghielmi
Publications and source records attributed to S Ghielmi.
Effect of congestive heart failure on rate of atrial natriuretic factor release in response to stretch and isoprenaline.
STUDY OBJECTIVE: The aim was to investigate the pattern of release of atrial natriuretic factor induced by mechanical and adrenergic stimulation from atria of rats with or without congestive heart failure. DESIGN: Monocrotaline, a pyrrolizidine alkaloid, was given to rats to cause severe pulmonary hypertension, leading to a marked degree of right ventricular hypertrophy and failure. Measurements of noradrenaline and atrial natriuretic factor were performed in each cardiac chamber and in plasma. Right and left atria of control rats and rats with congestive heart failure were isolated and subjected to mechanical or adrenergic stimulation to study the in vitro release of atrial natriuretic factor. MATERIALS: Studies were performed on plasma, ventricles, and isolated right and left atria of 276 male Wistar rats, 80-100 g weight, with or without congestive heart failure. MEASUREMENTS AND MAIN RESULTS: In monocrotaline rats right and left ventricular concentrations of noradrenaline were significantly reduced. In the same rats concentrations of atrial natriuretic factor fell to 15.2% in the right atria and to 65.5% in the left atria. Whole heart content of atrial natriuretic factor was diminished, while plasma concentrations were increased sevenfold. Isolated hypertrophied right atria of failing hearts did not release atrial natriuretic factor in response to stretch or to isoprenaline (10(-9)M) and they were insensitive to the inotropic action of isoprenaline. On the other hand, non-hypertrophied left atria from the same animals released increased amounts of atrial natriuretic factor under basal conditions and after both stimuli, despite reduced tissue stores of the peptide. CONCLUSIONS: Heart failure may deplete cardiac stores of noradrenaline and atrial natriuretic factor, especially in hypertrophied chambers, and can result in a decrease in the release of atrial natriuretic factor from atrial tissue in response to mechanical and adrenergic stimulation.
Animals↗
Quantitative immunoenzymatic assay of human lutropin, with use of a bi-specific monoclonal antibody.
In this immunoenzymatic assay for human lutropin (hLH) we used bi-specific antibodies (BiAbs) obtained from the fusion of two hybridomas producing antibodies to beta-D-galactosidase and hLh. The BiAb complexed with the enzyme beta-D-galactosidase was used as tracer in a double-determinant assay. We compared the assay involving the BiAb (Bi-EIA) with an immunoenzymatic assay (EIA) in which the same capture antibody was used but the tracer was an enzyme-conjugated hLH-specific monoclonal antibody produced by the same parental cell line used to produce the BiAb. The coefficient of correlation (r) between the two assays was 0.979 but the Bi-EIA was more sensitive (detection limits: 0.8 int. units/L for the Bi-EIA, 2.0 int. units/L for the EIA) and more specific (less than 0.04% vs less than 1.2% cross-reactions with human choriogonadotropin). Mean intra- and interassay CVs for the Bi-EIA were 2.9% and 5.9%, respectively. Correlation (r) with an immunoradiometric assay (IRMA, Serono kit) was 0.960, with radioimmunoassay (RIA, Biodata kit) 0.909, and with an enzyme-linked immunosorbent assay (ELISA kit, Specialty Medical Industries Inc.) 0.888, (n = 25). Evidently, bi-specific antibodies can be used successfully in immunoenzymatic assays, and with potentially greater sensitivity and specificity than assay with a traditional antibody-enzyme conjugate.
Antibodies, Monoclonal↗
Protein A, hydroxyapatite and diethylaminoethyl: evaluation of three procedures for the preparative purification of monoclonal antibodies by high-performance liquid chromatography.
Three rapid, reproducible and feasible monoclonal antibody purification procedures by means of high-performance liquid chromatography have been evaluated. The stationary phases employed were high-performance hydroxyapatite, high-performance Protein A and high-performance anion-exchange resin. The purity of the final immunoglobulin preparations was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions and, subsequently, by high-performance gel permeation chromatography. The immunoreactivity of purified monoclonal antibodies was determined by the radioimmunoassay method.
Animals↗
Prolonged protective effect of the calcium antagonist anipamil on the ischemic reperfused rabbit myocardium: comparison with verapamil.
To assess whether pretreatment with the calcium antagonist anipamil protects the heart against ischemic and reperfusion damage and to establish how long the protection persists after cessation of the therapy, rabbits were injected subcutaneously twice daily for 5 days with 2 mg/kg body weight of this drug. The heart was then isolated 2, 6, or 12 hours after the last injection and was perfused by the Langendorff technique during a control period and 90 minutes of total ischemia (37 degrees C), followed by 30 minutes of reperfusion. Diastolic and developed pressure was monitored; coronary effluent was collected and assayed for creatine phosphokinase (CPK); mitochondria were harvested and assayed for respiratory activity, ATP production, and calcium content; and tissue concentration of adenosine triphosphate (ATP) and creatine phosphate were determined. The data obtained with anipamil were compared with those obtained with verapamil administered to the rabbit at the same dose and following the same procedure. Pretreatment with anipamil induced a negative inotropic effect under normoxic conditions; reduced the rate and extent of depletion of ATP and creatine phosphate during ischemia, with an incomplete restoration of the nucleotides after reperfusion; maintained mitochondrial function and calcium homeostasis during ischemia and reperfusion; reduced the rate of CPK release; and improved the recovery of ventricular function on reperfusion. The protective effects of anipamil persisted for as long as 12 hours after the last administration. In contrast, the protective and negative inotropic effects of verapamil were no longer apparent in heart isolated 6 or 12 hours after the last dose of the drug.(ABSTRACT TRUNCATED AT 250 WORDS)
Adenosine Triphosphate↗
The antinatriuretic effect of dopaminergic blockade during volume expansion is independent of circulating atrial natriuretic factor.
1. Ten normal subjects were subjected to 2 h water immersion with and without pharmacological dopaminergic blockade with either metoclopramide (group I) or domperidone (group II). 2. In group I, urinary sodium excretion showed a marked increase during water immersion alone, whereas it was blunted during water immersion plus dopaminergic blockade with metoclopramide (P less than 0.05 vs water immersion alone, n = 5). Plasma aldosterone was significantly suppressed by water immersion alone (P less than 0.05), but remained unchanged during water immersion plus metoclopramide. Plasma atrial natriuretic factor showed similar augmentation during water immersion alone and during water immersion plus metoclopramide. 3. Another five subjects (group II) were studied during water immersion alone and during water immersion plus dopaminergic blockade with domperidone. In this group the increase in urinary sodium excretion was similarly blunted by dopaminergic blockade. Plasma atrial natriuretic factor was equally elevated during water immersion alone and during water immersion plus domperidone, but aldosterone was suppressed by both water immersion alone and water immersion plus domperidone. 4. Our findings suggest that water immersion-induced atrial natriuretic factor release is independent of dopaminergic activity. Dopamine blockade is able to blunt significantly both water immersion-induced natriuresis and plasma aldosterone suppression, independently of the marked elevation of circulating atrial natriuretic factor, via a mechanism involving type 2 dopaminergic receptors.
Adult↗
Effect of exogenous prostaglandin E2 on plasma antidiuretic hormone in normal man. Role of angiotension II.
To verify if exogenous prostaglandin E2 (PGE2) is able to release antidiuretic hormone (ADH) and if endogenous angiotensin II plays a role in this eventual PGE2-induced stimulation of vasopressin, increasing doses of PGE2 were infused in 6 normal volunteers before (PGE2 study) and after the administration of 100 mg of captopril (captopril study). PGE2, even at an infusion rate of 40 and 60 ng/kg/min, did not modify blood pressure when it was infused alone; a significant fall of blood pressure was observed, in contrast, in the captopril study. PGE2 alone doubled the plasma levels of ADH. One hour after the subjects had been pre-treated with captopril, plasma levels of ADH fell by about 38%, then they increased by about 60% during the infusion of PGE2. These results suggest that in normal man endogenous angiotensin II is an important non-osmotic regulator of plasma ADH and that exogenous PGE2 can stimulate maximally the release of ADH only when the renin-angiotensin system is not impaired.
Adult↗
Protective effects of gallopamil against ischemia and reperfusion damage.
To establish if the administration of gallopamil, a derivative of verapamil, protects heart muscle against the deleterious effect of ischemia and subsequent reperfusion, rabbits were injected subcutaneously twice daily with 2 mg/kg of Gallopamil for 5-6 days. The hearts were isolated and perfused with aerobic Krebs-Henseleit buffer solution by the Langendorff method. The hearts were paced (180 b/min) and wall temperature was controlled. Ischemia was induced by reducing coronary flow from 25 ml/min to 1 ml/min for 90 min and then the hearts were reperfused for 30 min. At the end of either the ischemic period or reperfusion, the hearts were assayed for ATP, CP, and calcium. Others were homogenized, their mitochondria harvested and monitored for oxidative phosphorylating and ATP generating activity as well as calcium content and uptake. The mechanical function of the hearts and noradrenaline release was also measured. Hearts that were made ischemic gained calcium, their endogenous stores of ATP and CP were depleted, their mitochondria had reduced RCI and state 3 respiration and increased calcium concentrations. During reperfusion tissue and mitochondrial calcium was significantly increased, the capacity of mitochondria to use oxygen for state 3 respiration was further impaired and their ATP generating capacity reduced. Diastolic pressure increased and there was no recovery of developed pressure and important noradrenaline release. Pretreatment with gallopamil protected the mitochondria against the ischemically induced changes in RCI, state 3 respiration. There was also a less marked rise in tissue and mitochondrial calcium and a reduced increase of diastolic pressure. Gallopamil also diminished the effect of reperfusion on the calcium accumulating activity of mitochondria and on the decline in the ATP generating and oxygen utilizing capacity of the mitochondria. The tissue levels of ATP and CP were better maintained, and noradrenaline release was reduced, the systolic pressure generating capacity was enhanced by the treatment with gallopamil. These results are discussed in accordance with the hypothesis that this drug protects heart muscle against the deleterious effects of ischemia and reperfusion by ensuring that sufficient ATP remains available to maintain homeostasis with respect to calcium.
Adenosine Triphosphate↗
Effect of reduction of blood volume on plasma immunoreactive atrial natriuretic factor concentrations in normal man.
Plasma immunoreactive atrial natriuretic factor (i-ANF) concentrations were measured in ten voluntary blood donors before and after acute blood loss induced after they had been supine for 20 min. Lying down caused i-ANF to increase significantly in all subjects. Bleeding (400 ml in 5 min) caused i-ANF to decrease to values significantly lower than either those observed before haemorrhage or those recorded in the upright position. These results provide evidence that in normal man acute changes in the intravascular volume, although limited within physiological limits, are able to induce opposite changes in i-ANF release.
Adult↗
Effects of changes in intravascular volume on atrial size and plasma levels of immunoreactive atrial natriuretic peptide in uremic man.
To study the trigger for the release of atrial natriuretic peptide (ANP) in man, we measured the atrial areas (AA) by 2-D echocardiography, the total blood volume (TBV) by 131I-serum albumin and plasma immunoreactive ANP (i-ANP) concentrations by radioimmunoassay, after prior plasma extraction, for 10 dialyzed uremic patients. Measurements were made when the patients were volume-loaded or volume-depleted by isoosmotic ultrafiltration and again 48 h later, when they were again volume-loaded. Analysis of plasma extracts by high-performance gel permeation chromatography revealed that the greatest amount of the i-ANP fraction was a peptide eluting like human synthetic alpha-ANP. Ultrafiltration consistently decreased the TBV, while spontaneous regain of body-fluids caused TBV to rise to pre-ultrafiltration levels. Changes in TBV were closely related in time to changes in both right (RAA) and left (LAA) atrial area and in plasma i-ANP concentrations. Significant direct relationships were found between TBV and RAA, TBV and i-ANP and between both LAA and RAA and i-ANP. Furthermore, the decreases and the increases in TBV, RAA and LAA were closely correlated with changes in i-ANP. Multiple regression analysis, however, revealed that the changes in plasma i-ANP were mainly related to the changes in RAA, with little or no relationship to the changes in TBV or LAA. These findings are evidence for a positive feed-back between the level of intravascular filing volume, extent of atrial distention and amount of i-ANP released into the blood stream.
Adult↗
Monoclonals and allergy. A review, with experimental contribution.
The role of monoclonal antibodies in allergy has been explored. First the status of art of monoclonal research in general is reviewed, by outlining a monoclonals identikit and the relevant technologies employed for their development. The attention is then focused on the present impact of monoclonals in the allergological field, first considering a general outline, and then the important steps of standardization of monoclonal antibodies. A comprehensive hint is made concerning the monitoring of immunotherapy, with future extrapolations on developing anti-idiotype vaccines, of which same examples can already be found in the infectious field, thus leaving the way open in allergy as well. A second section deals with the experimental contribution of the Authors, with the description of the preparation of the allergenic extracts of D.F., with details of the relevant steps (rabbit immunization; extract characterization; techniques used for monoclonal screening and characterization). The results obtained are discussed in relation to the techniques employed, weighing the reciprocal advantages and drawbacks.
Animals↗
[Release of atrial natriuretic factor following the stretching of the atrium of rats in vitro].
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Animals↗
[Neuropeptides in human carotid gliomas].
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Aged↗
Use of a reference standard to improve the accuracy and precision of seven kits for determination of ferritin in serum.
We assessed the accuracy and precision of seven commercial kits for serum ferritin. The concentration of ferritin as determined by these assays for a liver ferritin reference standard, a human heart ferritin standard, and normal sera correlated highly, but the absolute values varied widely. Use of an international reference standard for ferritin to prepare the standard curve greatly diminished the variability, but did not eliminate it. Although the seven kits differed in specificity for various human isoferritins, this did not appear substantially to affect accuracy. Six of the seven kits appeared sufficiently precise for clinical use over a wide range of ferritin concentrations.
Ferritins↗
Methodological effects on the quantitation of serum ferritin by radio- and enzymoimmunoassays.
Serum ferritin is normally quantitated by sensitive radio- or enzymoimmunoassays, which are based either on a competitive reaction between the unlabelled and labelled antigen (RIA), or on a non-competitive reaction between the sample and the labelled antibody (IRMA and ELISA). Both methods appear to be satisfactory for the clinical evaluation of serum ferritin. However, the effect of these methods on the quantitation of serum ferritin has never been carefully studied. This paper describes and compares five different immunoassays for the evaluation of serum ferritin: two competitive RIAs, one non-competitive IRMA and two non-competitive ELISAs. The same anti-ferritin antibody and ferritin standards were used for all the assays. The RIAs were found to be less sensitive than either the ELISAs or the IRMA, and all showed a similar degree of cross-reactivity with ferritin extracted from spleen and HeLa cells. A significant difference between the assays was found in the determination of serum ferritin: in fact the RIAs over-estimated serum ferritin by about 50% more than the IRMA, whereas the ELISAs under-estimated serum ferritin by about 15% less than the IRMA.
Antibody Specificity↗
[Radioimmunological determination of circulating thyroid hormones].
In our study of the thyroid function, the methodological aspects and clinical significance of TSH, T4, T3 and their respective free fractions (FT4 and FT3), are examined. The RIA of TSH is the best for the diagnosis of hypothyroidism and also for the evaluation of the effect of thyroid hormone substitution therapy. This, united with T4 and T3 assay, allows a total evaluation of the thyroid state. The new method, recently introduced, for direct assay of free fractions, using a chromatographic separation of Sephadex LH 20, is extremely useful for follow-up of patients with thyroid disfunction.
Humans↗
[Human chorionic somatommamotropins (HCS or HPL) : radioimmunologic determination and clinical significance].
The AA. have studied a new standardized radioimmunologic method for the routine determination of HCS. All the steps of the analysis have been studied, in particular those concerning the reability test and the precipitation of the complex with PEG. The best conditions were found when PEG 6000 is used at a concentration between 14-16 g in 100 ml (v/w), dissolved in veronal buffer, pH 7.4--9.4, with a dilution of protein (bovine serum) 1:4 in the incubation mixture. The reability test have given very good results. The c.p.m. of the analysis are plotted with a logit plot by computer which directly gives the values in ng/ml of the hormone in the plasma sample. The results obtained with this method are compared with those of the literature; the most striking difference in the present method appears in the last trimester of pregnancy in which the result have a low S.D. and can give a good help in clinical management of pregnant patients.
Abortion, Threatened↗
[Diazoxide test in the diagnosis of arterial hypertension: modifications in the levels of renin and aldosterone in blood of patients with various restrains of the renal function].
The AA. have applied the diazoxide test for the screening of primary hiperaldosteronism to 22 nephropatic patients suffering from hypertension and with different degrees of renal function. In 22 patients an increase in PRA and aldosterone values always followed the diazoxide infusion. Only one patient, likely suffering from primary aldosteronism, showed no increase in PRA and aldosterone values. The diazoxide infusion had no influence on renal, pancreatic and cardiovascular function. Therefore, this can be considered as a valid test easy to be performed in a short time, also in nephropatic patients who are very sensitive to pharmacological noxae.
Adolescent↗