[Effects of intravenous administration of clarithromycin on plasma levels of gastrin and group I pepsinogen]. / Effetti della somministrazione venosa di claritromicina sui livelli plasmatici di gastrina e pepsinogeno del gruppo I.

Erythromycin and some of its derivatives have prokinetic gastrointestinal properties. In addition, erythromycin has been shown to stimulate isolated chief cells of the gastric mucosa, and to activate pepsin secretion. The above study was aimed at ascertaining in a group of dyspeptic patients whether clarithromycin, a structural analogue of erythromycin, is apt to modify certain functional parameters of gastric secretion, above all the patterns of gastrin and PG-I secretion. A 20-minute intravenous clarithromycin infusion (1.5 mg/kg) in fasting subjects has brought about a significant reduction (at 20 and 45 minutes from the start of infusion) of circulating gastrin (about 23%) and, after a meal, a 69% increase. No change of plasma PG-I level was observed either after placebo or after the active substance. These findings suggest that in vivo and at the doses used in our experiment clarithromycin has no influence on plasma PG-I release and is apt to modify the fasting and postprandial gastrin releasing pattern.

Failure to find evidence of immunoglobulin inhibitor(s) of thyroid hormone binding to serum proteins in non-thyroid illnesses.

In order to verify the hypothesis of the presence of IgM (or an IgM-like substance) capable of inhibiting thyroid hormone binding to serum proteins and, therefore, capable of enhancing serum free thyroid fractions in non-thyroid illnesses (NTI), we measured TBG and TBPA maximum binding capacities and TBG concentration by an immunoradiometric system in normal pooled sera (NPS) before and after enrichment with purified immunoglobulins (IgM and IgG) from euthyroid NTI sera (free T4, free T3 and TSH levels were normal). A known amount of TBG was diluted 1:2-1:6 with deionized water or with IgM from NPS or from each of 6 NTI sera; the measured values were not different from these expected on theoretical grounds. Likewise, IgM or IgG from normal or from each of 7 NTI sera failed to modify both TBG and TBPA capacities of different NPS, and NTI immunoglobulins showed no binding activity directed to [125I]T4, [125I]T3 or [125I]TBG. In addition, no inhibitory influence of TBG and TBPA capacities was observed when the whole euglobulin fraction obtained by precipitating the same 7 NTI sera by PEG was mixed with NPS. On the other hand, a significant IgM inhibitory effect on the binding of labelled T4 to TBG was found, only when IgM concentrations were experimentally rendered 41 times greater than that requested in the working mixtures. We conclude that no immunoglobulin inhibitor of thyroid hormone binding to transport proteins was evident in the NTI sera investigated.