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Biomedical subjects

S Turchi

Publications and source records attributed to S Turchi.

11 recordsLinked to original sources
PubMed2000

Polyfunctionalized cage compounds by pericyclic domino processes of 4,5-dicyanopyridazine with dienes: applications and limits

The title compound 1 was found to behave as an attractive masked bis-diene to give 4-oxatricyclo[4.3.1.0(3,7)]dec-8-ene, 5-aza- and 5-silatricyclo[5.3.1.0(3,8)]undec-9-ene, tricyclo[3.2.1.0(2, 7)]oct-3-ene, and tricyclo[5.3.1.0(3,8)]undec-9-ene derivatives through purely pericyclic, three-step homodomino processes with diverse bis-dienophiles; whereas the reaction with myrcene (21) was characterized by a complete sitoselectivity affording compound 25, treatment of 1 with (R)-(-)-beta-citronellene (26a) gave a 3:1 mixture of the homochiral diastereomers 30a and 31a. Some limits of this methodology, mainly arising from competitive side reactions upon the key cyclohexa-1,3-diene intermediates, are emphasized. The structures of the new compounds were established on the basis of spectral data.

Journal Article↗
PubMed1996

Analytical performance and clinical usefulness of a commercially available IRMA kit for measuring atrial natriuretic peptide in patients with heart failure.

We evaluated the analytical characteristics and clinical usefulness of a commercially available IRMA kit for measuring plasma concentrations of atrial natriuretic peptide (ANP) in healthy subjects and in patients with heart failure. The method uses two monoclonal antibodies prepared against sterically remote epitopes of the ANP molecule; the first antibody is coated on the solid-phase beads, and the second is radiolabeled with 125I. Fifty-nine healthy subjects and 77 patients with heart failure were studied. After subjects had rested 20 min in a recumbent position, blood samples were collected from a brachial vein into ice-chilled disposable polypropylene tubes containing aprotinin and EDTA. Plasma samples were immediately separated by centrifugation and stored at -20 degrees C until assay. The working range (CV <15%) was 10-2000 ng/L. The detection limit (2.13 +/- 0.91 ng/L) was similar to those reported for other IRMAs but was much better than those of RIAs. For healthy subjects, the results of this method (18.0 +/- 10.6 ng/L, range 4.7-63 ng/L, median 16.7 ng/L, n = 59) were similar to those generally reported for the most accurate methods, i.e., those using preliminary extraction and chromatographic purification of plasma samples. Measured plasma ANP was significantly associated with the severity of clinical symptoms, i.e., NYHA class (ANOVA, P <0.0001), and with the left ventricular ejection fraction (n = 62, r = 0.618, P <0.0001). Patients with severe heart failure showed greatly increased values (NYHA III-IV: 257.4 +/- 196.6 ng/L, n = 23).

Adult↗
PubMed1995

Measurement of serum amiodarone and desethylamiodarone by HPLC: its usefulness in the follow-up of arrhythmic patients treated with amiodarone.

Amiodarone is an antiarrhythmic agent used for the treatment of supraventricular and ventricular arrhythmias. Owing to its narrow therapeutical range, monitoring of drug concentration is mandatory. The circulating and tissue levels of amiodarone and of its main endogenous metabolite, N-desethyl-amiodarone, are currently measured by means of HPLC procedures, which are tedious and time-consuming, and often beset with problems and drawbacks. We have developed a new chromatographic assay for the simultaneous measurement of amiodarone and N-desethyl-amiodarone in serum samples, and tested its usefulness in the follow-up of 14 patients (8 men and 6 women, age range 40-65 years) with complex ventricular arrhythmias, treated with amiodarone for at least 5 weeks. This assay uses trifluoperazine dihydrochloride as internal standard and a preliminary extraction of serum samples with isopropyl ether. The assay procedure was the following: 350 microliter patient's serum, to which 1 microgram trifluoperazine was added, were extracted with 280 microliter isopropyl ether. After mixing and centrifugation, 50 microliter of the organic layer were filtered and then injected onto the HPLC system (15 cm x 3.9 mm Resolve 5-micrometer spherical silica column); the elution rate was 1.8 ml/min (mobile phase, 920 ml of methanol and 80 ml of ammonium sulfate buffer) in isocratic condition. The time for a complete assay of each serum sample was less than 20 min, and its working range was 0.1-5.0 microgram/ml of amiodarone. An excellent recovery of the drug from subtherapeutical values up to toxic amiodarone concentration was obtained. The intra-assay precision of amiodarone assay ranged form 5 to 11%, while the between-assay precision administered in all patients, without increasing the amiodarone concentration beyond the toxic threshold level. The plateau of the circulating levels of the drug was generally reached in about 5-12 days, at the acceptable therapeutical range, from 0.5 to 2 microgram/ml. In conclusion, this chromatographic method for the assay of serum amiodarone levels is sufficiently simple, rapid and reliable to be considered a useful tool in the follow-up of arrhythmic patients chronically treated with amiodarone.

Adult↗
PubMed1993

Disposal and distribution of rT3 in humans: a new double-tracer kinetic study.

A satisfactory definition of reverse 3,3',5'-triiodothyronine (rT3) kinetics in humans cannot be obtained if the plasma disappearance curve of the injected labeled hormone is the only experimental data available; most of the kinetic parameters can only be bounded within ranges showing unacceptable variabilities. To gain additional experimental data a double-tracer approach is proposed. After simultaneous injection of [125I]rT3 and 131I the following three experimental curves were determined in plasma: 1) the disappearance of [125I]rT3, 2) the disappearance of 131I, and 3) the appearance of 125I generated in vivo from labeled rT3 degradation. Combined analysis of these three curves, based on a complex six-compartment model, was developed and applied to data obtained in a group of normal subjects. Through this new analysis, fractional disposal rates and fractional exchange rates between the plasma compartment and the periphery are uniquely determined. The main physiologically interesting information on the degradation of the hormone that emerges from these studies are 1) all degradative pathways of rT3 generate iodide, being in all cases the [125I]rT3 dose completely recovered as 125I in plasma; and 2) most rT3 is degraded (65-90%) in peripheral tissues rapidly exchanging with the plasma pool. The extended experimental base is not yet sufficient to compute unique values for production rate (PR) and body mass (Qt); the validity of estimates of PR and Qt is based on the assumption that injected [125I]rT3 is able to trace all rT3 peripherally produced (from thyroxine). The new approach yields ranges for PR and Qt (1.12-2.15 micrograms/h and 2.88-8.24 micrograms) much narrower than those computable from the [125I]rT3 disappearance curve only (1.12-5.07 micrograms/h for PR and 2.88-23.7 micrograms for Qt).

Adult↗
PubMed1993

Chromatographic identification in serum of endogenously radioiodinated thyroid hormones after iodine-131 whole-body scintigraphy in the follow-up of patients with differentiated thyroid carcinoma.

Patients with differentiated thyroid cancer (DTC) are conventionally followed with serial 131I whole-body scintigraphy (WBS) and serum thyroglobulin (hTg) assay. Given the 15%-20% incidence of discordant results, we developed a sensitive and specific procedure for monitoring such patients, based on the assumption that 131I uptake, even if too low to be detected by 131I WBS, could be assayed in serum as thyroid products (hTg, T3 and T4) endogenously labeled with 131I. Our study included 125 patients routinely monitored for tumor recurrence or for the persistence of functioning thyroid tissue after complete primary treatment for DTC (surgery and 131I ablation of remnants). A plasma sample, taken 72 hr after administering 131I for WBS was fractionated on a Sephadex-G25 superfine column by first eluting all of the radioactive species except the thyroid hormones and then the radioiodothyronines. The sensitivity and specificity of chromatography in detecting functioning thyroid tissue after primary treatment for DTC were 98.4% and 100% (accuracy 99.2%), respectively, versus 90.6% and 95.1% for 131I WBS (accuracy 92.8%) and 60.9% and 100% for hTg (accuracy 80%). Combining chromatography with serum hTg gave the highest gains in diagnostic performance (100% for all parameters). This chromatographic method can be used in addition to conventional procedures in the follow-up of patients with DTC and represents a highly sensitive test for assessing the results of 131I ablation of postsurgical remnants.

Adolescent↗
PubMed1978

Hypophyso-gonadal function in the diabetic child.

14 diabetic boys (five with a family history of diabetes and nine without) and 29 "short normal" boys were studied. A gonadal function test (2.000 IU of hCG i.m. for 3 days and plasma testosterone assay before and after the hCG administration) as well as an LH-RH test (50 microgram i.v.) were carried out. While basal testosterone level turned out to be similar in the two groups of children, it was significantly lower (p less than 0.01) after hCG than the mean value of the control group. This difference was mainly observed in those patients with a family history of diabetes. In the diabetic children, basal LH level was normal and the pituitary LH reserve was lower than in the control group. Both basal FSH level and FSH pituitary reserve were lower than in normal children. These data show that an alteration in the hypothalamus-pituitary-gonadal function is already evident in the diabetic child.

Adolescent↗