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Biomedical subjects

M G Del Chicca

Publications and source records attributed to M G Del Chicca.

At least 55 records · Page 3Linked to original sources
PubMedDate not supplied

Progressively elevated levels of biologically active (free) cortisol during pregnancy by a direct radioimmunological assay of diffusible cortisol in an equilibrium dialysis system.

The measurement of free cortisol would be preferable with respect to the total hormone content, since it yields more reliable information about the plasma levels of the biologically active cortisol. We have developed a new method for the determination of the apparent free plasma cortisol concentration (AFCC) by means of direct radioimmunological measurement of dialyzed cortisol. The AFCC was measured in 23 plasma pools obtained from normal pregnant women at various gestational times and in 18 nonpregnant women. The mean AFCC was 19.5 +/- 7.1 ng/ml in pregnant women and 9.0 +/- 6.2 ng/ml in nonpregnant women (p less than 0.005). The percent of free cortisol (%FC) showed a progressive increase during pregnancy reaching the lower limits of the normal range at the third trimester. However, the mean of %FC was significantly lower (p less than 0.005) in pregnant women than in nonpregnant women. Our data show a progressive increase of biologically active cortisol during pregnancy.

Dialysis↗
PubMedDate not supplied

Endogenous digitalis-like factors (EDLF) in obese individuals: preliminary results.

We measured by RIA the serum and urinary digoxin-like immunoreactivity (EDLF) in 8 subjects with severe obesity and in 10 healthy, non-obese individuals (as a control group), to evidentiate whether circulating and urinary levels of EDLF are increased in obesity. For each individual, we measured the mean EDLF on two sera collected consecutively on two successive mornings, between 8-9 a.m. and the daily urinary EDLF excretion. Every subject collected his/her 24 hour urine in 5 different timed fractions. For each urine fraction, we measured the excretion of EDLF, electrolytes (Na and K), and creatinine. In obese people, the mean serum digoxin-like immunoreactivity (no. 8, 27.3 +/- 8.7 ng/L de) was significantly higher (unpaired t test, p = 0.0002) than in the controls (no. 10, 12.0 +/- 7.3 ng/L de), whereas control and obese subjects had superimposable 24 hour EDLF urinary excretion. Urinary excretion of EDLF significantly changed throughout the day in normals, but not in obese people. In a multiple stepwise regression analysis, urinary K+ and Na+ significantly (p less than 0.01) contributed to the regression with urinary EDLF (EDLF = 76.9 + 0.67 K+ - 0.24 Na+; R = 0.601, no. 40) in obese individuals. The in vivo kinetic and metabolic pathways of EDLF are conceivably different in obese and normal subjects. A difference in the production rate, binding to plasma proteins and/or removal mechanisms could explain the findings of higher circulating levels with normal EDLF urinary excretion in obese persons.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Evaluation and comparison of the analytical performances of two RIA kits for the assay of atrial natriuretic peptides (ANP).

We evaluated the analytical performance of two commercial RIA kits for the assay of plasma atrial natriuretic peptide (ANP), which use different antisera and tracers, in order to verify the most suitable RIA procedure for the assay of ANP in plasma samples. In particular, two different procedures for the purification of plasma were evaluated. The first one uses the extraction of plasma samples with Sep-Pack C18 cartridges and the second immunoextraction (C-terminal ANP-specific antibody bound to solid phase of Sepharose). The sensitivity and precision of the two RIA kits proved inadequate, being unable to provide an acceptably precise measurement of the plasma ANP concentrations in normal subjects. An improvement in precision and sensitivity was obtained by using "fresh" (or purified) preparations of the tracer and standard solutions, and by adding PEG to the B/F separation step. The direct assay (without preliminary purification) was not possible due to a serious overestimation of plasma levels due to the presence of interferences; on the other hand, the extraction step increased the imprecision and the complexity of the assay. Moreover, the extraction recovery of ANP added to plasma samples in the procedure using Sep-Pak cartridges is about 50-60%, while it was found to be almost complete (about 90%) in the immunoextraction procedure. Moreover, a comparison of the results obtained with the two RIA systems indicated that the antisera have comparable sensitivities, but quite different specificities; however, neither of the two RIA kits showed a completely satisfactory degree of sensitivity, precision and practicability.

Atrial Natriuretic Factor↗
PubMedDate not supplied

Radioreceptor assay for the measurement of endogenous digitalis-like factors using membrane particulate fraction of human placenta and 125I-digoxin: comparison with RIA method.

We measured purified extracts of serum (plasma) or urine samples of newborns, pregnant women, normal adults, and uremic patients by a radioreceptor assay (RRA), which uses particulate membrane fractions from human placenta as a binding system, and 125I-digoxin as a tracer. We also measured the digoxin-like immunoreactivity by a sensitive RIA, and results were compared with those found by the RRA. Specific 125I-digoxin binding to placental receptors was competitively inhibited by purified plasma and/or urine extracts of newborns, adult subjects, pregnant women and uremic patients. A linear relationship was found between inhibition of binding and volume of plasma and urine assayed. Moreover, a significant correlation was found between the values obtained by RRA and those found by RIA (n = 17, r = 0.699, p = 0.0012). Our data confirm that increased circulating and/or urinary levels of substances with biological and immunological activity similar to cardiac glycoside drugs are present in newborns, pregnant women and uremic patients compared to healthy adult subjects. In addition, our preliminary study indicates that these endogenous factors are able to bind to the specific receptor of digitalis drugs on the placental membranes.

Adult↗