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CTLA4 protein is a receptor molecule that plays a critical role as a negative regulator of the immune response. Therefore, genetic variations in CTLA4 may confer susceptibility to autoimmune diseases such as multiple sclerosis (MS). In order to investigate the association of two CTLA4 polymorphisms (+49 A/G and -318 C/T) with multiple sclerosis, sporadic MS patients and healthy controls from Italy were genotyped through direct DNA sequencing. Considering single-loci variations, no differences in the allelic and genotypic frequencies between patients and controls were found. However, considering a putative interaction at the two loci, the T/G combination was more frequently observed in patients than in controls. This result suggests that this allelic combination of the CTLA4 polymorphisms may be involved in the susceptibility to MS in the Italian population.

For a reappraisal of the current perplexing notion that the small intestine of the rat lacks in vitro opiate receptor binding, crude microsomal fractions were prepared from longitudinal muscle with attached myenteric plexus, isolated from rat small intestine, carefully dissected free from the mesentery. These preparations, when incubated with the potent opiate etorphine, tritium labelled at high specific activity (31 Ci/mmole), exhibited high affinity (K D = 1.2 nM) saturable binding. This in vitro binding of 3 H-etorphine (2×10 −9 M) was stereospecific, since it was completely prevented by 1×10 −6 M levorphanol and unaffected by the same concentration of dextrorphan. When 10 mM NaCl was added, considerably less naloxone was required than in control medium for inhibiting the binding of tritiated etorphine to the rat small intestine longitudinal muscle microsomal preparation. Our present evidence for substantial in vitro opiate receptor binding in the rat small intestine agrees with previous results of pharmacological and in vivo binding studies supporting the existence of specific sites of action for narcotics therein.

Scatchard analysis of 3H-dihydromorphine (3H-DHM) binding to rat brain subcellular fractions gave a curvilinear plot in the microsomal (P3) and a linear plot in the mitochondrial (P2) fraction, respectively. In contrast, plots of 3H-ethylketocyclazocine (3H-EK) binding were linear in the P3 and curvilinear in the P2 fraction. No differences were seen in the potency of morphine and ketazocine in displacing either 3H-DHM or 3H-EK in the P2 fraction. In the P3 fraction, however, morphine was more potent than ketazocine in displacing 3H-DHM, but the reverse was true when 3H-EK was used as the ligand. Isolation of the P3 fraction may facilitate the demonstration of a kappa receptor in the rat brain.