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Biomedical subjects

C Iacobello

Publications and source records attributed to C Iacobello.

At least 19 recordsLinked to original sources
PubMed1994

Effect of pyridostigmine on the hydrocortisone-mediated decrease of circulating growth hormone levels in acromegaly.

The aims of our study were to investigate the effect of the acetylcholinesterase inhibitor pyridostigmine (PD) administration on growth hormone (GH) secretion in acromegaly and to investigate the effects of PD on GH levels following an i.v. infusion of hydrocortisone in acromegaly. We studied five adult patients with active acromegaly, three men and two women with a mean age of 60 +/- 5 years (range 47-71 years) and a mean BMI of 27 +/- 0.7 kg/m2 (range 24-28 kg/m2). All the patients underwent: 1) placebo, 2 tablets po or 2) PD, 120 mg po, at time -60 plus a bolus i.v. injection of 100 mg hydrocortisone succinate in 2 ml saline at time 0 followed by an i.v. infusion of 250 mg hydrocortisone succinate in 250 ml saline from 0 to 120 min, or 3) PD, po or 4) placebo, po at time -60 plus a bolus i.v. injection of 2 ml saline followed by an i.v. infusion of 250 ml saline from 0 to 120 min. Serum GH values did not significantly change after PD administration compared to those during placebo treatment and with respect to baseline levels. In all of the acromegalic patients during hydrocortisone succinate infusion, GH values clearly decreased with respect to basal levels in varying degrees, with a nadir between 90 and 180 minutes after the beginning of hydrocortisone infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Acromegaly↗
PubMed1993

The effect of the concentration ratio of avidin and biotin on a single step sandwich enzyme immunoassay.

The interaction between biotin and avidin, used in a single-step enzyme-immunoassay for ferritin determination, has been studied. The antigen is simultaneously bound by an antibody coated to a polystyrene bead and by an antibody coupled to biotin which reacts with avidin conjugated to peroxidase. We have assessed the optimal ratio between avidin, conjugated to peroxidase, and biotin, coupled to antibodies, to give rise to the best signal for a quantitative enzyme-immunoassay. We have found that a careful balance between biotinylated antibody and conjugated avidin is necessary for our purpose and a biotinylated antibody excess should be avoided since it causes a signal decrease. This ratio is uninfluenced by both the presence and the absence of the antigen. Thus, an avidin-biotin single-step methodology, which has proved to be reliable for routine use, was developed.

Antigen-Antibody Complex↗
PubMed1993

Comparison of two time-resolved fluoroimmunoassays (TR-FIA), as applied to oestriol in human serum and progesterone in bovine milk.

We compared two time-resolved fluoroimmunoassay systems for measuring free oestriol in human serum and progesterone in bovine milk. By reading the fluorescence of europium complex of 4,7-bis(chlorosulphophenyl)-1,10-phenanthroline-2,9-dicarboxylic acid in solution, the measuring range is increased for both oestriol (10-50,000 ng/l instead of 25-50,000 ng/l) and for progesterone (10-50,000 ng/l instead of 25-10,000 ng/l). In addition, the interassay coefficients of variation were lowered from 9.5 to 5.7% for oestriol and from 7.5 to 5.4% for progesterone, at the smaller hormone concentrations detectable by each method.

Animals↗
PubMed1992

Affinity of europium-labelled proteins A and G for immunoglobulin G from seven mammalian species.

Proteins A and G were each labelled with two different europium chelates (p-isothiocyanatophenyl-ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid). Their affinities for IgG from rabbit, goat, horse, sheep, mouse, pig, and rat were then measured using time-resolved fluorescence. Protein G labelled with the second chelate was found to be especially effective in binding to goat and horse IgG.

Affinity Labels↗
PubMed1990

A mutational analysis of the epitopes of recombinant human H-ferritin.

Murine monoclonal antibodies were elicited by the recombinant human H-ferritin overexpressed in Escherichia coli. They had a specificity analogous to that of the antibodies elicited by natural human H-chain, and all of them showed low additivity in binding the recombinant ferritin. Four antibodies of each group were challenged with four H-ferritin mutants overexpressed in E. coli, altered in different accessible areas of the molecule. They consisted of deletions of the first 13 and last 22 amino acids, a duplication of an 18 amino acid sequence in the loop region, and a substitution of a 5 amino acid stretch in the three-fold symmetry axis region. Double diffusion, immunodot analyses and inhibition plots indicated that: (1) all the mutants were recognized by at least one antibody; (2) the deletion of the N-terminus and the duplication in the loop region had the strongest effect on antibody binding; and (3) epitope boundaries of the various antibodies could not be recognized. The antibodies were tested with H-containing ferritins from rat and hen hearts, and showed low or absent reactivities despite their high structural homology with human ferritin. Comparison of the amino acid sequences of human, mouse, rat and hen H-chains, together with mutational data, suggested that; (i) ferritin epitopes are large, probably encompassing a large portion of the subunit surface and (ii) Thr-5 and Cys-90 have a role in H-ferritin immunogenicity.

Amino Acid Sequence↗
PubMed1986

Immunochemical characterization of human liver and heart ferritins with monoclonal antibodies.

A library of 27 murine monoclonal antibodies was obtained by using human liver and heart ferritins as immunogens. The specificity of the antibodies for the two ferritins and their subunits was studied with five different methods. The antibodies elicited by the liver ferritin bound preferentially the immunogen and were specific for the L subunit. Some antibodies elicited by the heart ferritin had characteristics similar to the anti-liver antibodies, other ones bound preferentially the heart over the liver ferritin and were specific for the H subunit. Only two antibodies were able to bind both ferritins and subunits. Some anti-H and anti-L chain antibodies were used to develop and compare four types of immunoassay to quantitate isoferritins. The results indicate that heart ferritin is immunologically more heterogeneous than liver, the H and L subunits having large immunological differences with few, if any, identical epitopes; and that that the architecture of the immunoassays have a strong influence on the crossreactivity of the antibodies with the two isoferritins, probably because H and L chains are not arranged randomly in the assembled protein.

Animals↗
PubMed1985

Immunological reactivity of serum ferritin in patients with malignancy.

Serum ferritin has been suggested as a tumor marker in the diagnosis of certain malignancies and for following the activity or dissemination of the malignant process. Since neoplastic tissues generally contain more acidic isoferritins than their normal tissue counterparts, it has also been suggested that the specific assay of such isoferritins in serum may be of particular value in the diagnosis of malignancy. In this work, we have evaluated ferritin concentration in the serum of normal subjects and patients with acute nonlymphocytic leukemia, Hodgkin's disease, breast cancer and lung cancer by simultaneously using three different immunoassays: an immunoradiometric assay based on polyclonal antibodies against human liver (basic, L-subunit rich) ferritin, a radioimmunoassay based on polyclonad antibodies against HeLa cell (acidic, H-subunit rich) ferritin, and an immunoradiometric assay based on the monoclonal antibody 2A4 raised against human heart (acidic, H-subunit rich) ferritin. Most of the patients studied had increased values for liver-type ferritin in the absence of increased iron stores. Binding of serum ferritin to concanavalin A did not prove to be useful in distinguishing a tumor-specific basic isoferritin. The HeLa ferritin assay was found to be less specific than the heart ferritin assay in the detection of acidic isoferritins, and did not provide any advantage over the liver assay in detecting the increased levels of serum ferritin associated with malignant disease. Heart-type ferritin was found in one-fifth of normal sera and 64% of sera from patients with malignancy. Values were very low compared with those for basic ferritin, ranging from less than 0.1 to 17% of total serum ferritin (geometric mean value 1.3%) in patients with malignancy. These findings indicate that at present there is little application for serum ferritin immunoassays based on antibodies to HeLa cell or heart ferritin in the diagnosis or monitoring of malignant disease. This seems to be due to the presence in human serum of biding factors which are responsible for the rapid clearance of acidic isoferritins from the circulation. The serum concentration of basic ferritin, however, can be useful in the diagnosis and management of some malignancies, and it is possible that studies on cell isoferritins can be important in biologic monitoring of neoplastic disorders. It should also be noted that the increased levels of serum ferritin found in patients with malignancy can exert adverse effects on the host immune response and perhaps an inhibitory effect on hematopoiesis.

Antibodies, Monoclonal↗
PubMed1985

Use of a monoclonal antibody against human heart ferritin for evaluating acidic ferritin concentration in human serum.

Immunoassays for acidic ferritins rich in H subunits have shown that these isoferritins are predominant in some cells such as monocytes and red blood cells but have provided conflicting results about their presence in human serum. We have used an immunoradiometric assay based on a monoclonal antibody against human heart ferritin (monoclonal 2A4) for evaluating acidic ferritin concentration in human serum. This assay proved to be highly specific for acidic isoferritins having more than 60% H subunits. Heart-type ferritin was detected in only one fifth of normal sera and sera from patients with iron overload; values were very low compared with those for basic ferritin. Acidic ferritin was found in relatively high concentrations in most patients with iron deficiency anaemia. In other disease states characterized by increased serum concentrations of basic ferritin, acidic ferritin was always less than 21% of the total ferritin. Dialysis in low-ionic-strength buffer showed that both normal and pathological sera had binding factors for human heart ferritin. We conclude that: (i) human serum contains low concentrations of acidic isoferritins which, at variance with basic ferritin, do not appear to be directly related to the amount of storage iron; (ii) the findings of the present study reinforce the opinion that basic and acidic ferritins have different functional behaviours.

Anemia, Hypochromic↗
PubMed1984

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↗
PubMed1983

Basic and acidic isoferritins in the serum of patients with Hodgkin's disease.

Ferritin concentration has been measured in the serum of patients with Hodgkin's disease (HD) by radioimmunoassays with monospecific antibodies to liver (basic) and HeLa (acidic) ferritin. Elevated levels of serum ferritin with the liver ferritin assay were found only in patients with systemic disease, and were associated with low serum iron. Basic ferritin levels returned promptly to normal when complete remission was achieved. High levels of serum ferritin with the HeLa ferritin assay were found in 94% of all untreated patients. Acidic ferritin concentration was not related to systemic symptoms or alterations of iron metabolism, and returned to within the normal range only 1-2 yr after complete remission. These findings suggest that basic and acidic isoferritins can be distinguished in terms of biological and clinical significance. Basic ferritin is synthesized by the reticuloendothelial cells and the high values found in patients with systemic symptoms are compatible with the non-specific changes known to occur in the reticuloendothelial system during inflammation. In patients with untreated HD an elevated serum concentration of basic ferritin can be considered a marker of systemic symptoms and, therefore, an unfavourable prognostic factor. Acidic ferritin may be derived from abnormal lymphocytes and/or monocytes, including malignant cells, and its serum concentration may be of value in following the course of remission.

Adolescent↗
PubMed1982

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↗