Alessandro Turini

Effect of nepadutant at tachykinin NK2 receptors in human intestine and urinary bladder

We have characterized the action of the tachykinin NK(2) receptor antagonist nepadutant (c¿[(beta-D-GlcNAc)Asn-Asp-Trp-Phe-Dpr-Leu]c(2 beta-5 beta)¿) in the human isolated ileum, colon and urinary bladder. Nepadutant (30-1000 nM) competitively antagonized neurokinin A- or [beta Ala(8)]neurokinin A-(4-10)-induced contractions in all tissues, with pK(B)=8.3 (ileum and colon) and pK(B)=8.5 (bladder). In contrast, the nonpeptide tachykinin NK(2) receptor antagonist SR 48968 (or (S)-N-methyl-N [4-acetylamino-4-phenylpiperidino)-2-(3, 4-dichlorophenyl) butyl] benzamide) (30-1000 nM) produced insurmountable antagonism in all preparations. The tachykinin NK(2) receptor blockade produced by nepadutant in the colon was fully reversed by washout, whereas that produced by SR 48968 was not. Nepadutant (1 microM) greatly reduced (by 70-80%) the nonadrenergic noncholinergic (NANC) contractile off-response evoked by electrical field stimulation in the human ileum, and almost abolished it in the presence of the tachykinin NK(1) receptor antagonist GR 82334 (or: [[(S,S) Pro-Leu (spiro-gamma-lactam)](9,10),Trp(11)]Physalaemin (1-11)) (1 microM). The present results show that nepadutant is a potent, competitive and reversible antagonist at human tachykinin NK(2) receptors and provide further evidence that tachykinins act as excitatory NANC neurotransmitters in the human small intestine.

Evidence that PAR-1 and PAR-2 mediate prostanoid-dependent contraction in isolated guinea-pig gallbladder

We have investigated the ability of protease‐activated receptor‐1 (PAR‐1), PAR‐2, PAR‐3 and PAR‐4 agonists to induce contractile responses in isolated guinea‐pig gallbladder. Thrombin, trypsin, mouse PAR‐1 activating (SFLLRN‐NH2) peptide, and mouse PAR‐2 activating (SLIGRL‐NH2) and human PAR‐2 activating (SLIGKV‐NH2) peptides produced a concentration‐dependent contractile response. Mouse PAR‐4 activating (GYPGKF‐NH2) peptide, the mouse PAR‐1 reverse (NRLLFS‐NH2) peptide, the mouse PAR‐2 reverse (LRGILS‐NH2) and human PAR‐2 reverse (VKGILS‐NH2) peptides caused negligible contractile responses at the highest concentrations tested. An additive effect was observed following the contractile response induced by either trypsin or thrombin, with the addition of a different PAR agonist (SFLLRN‐NH2 and SLIGRL‐NH2, respectively). Desensitization to PAR‐2 activating peptide attenuated the response to trypsin but failed to attenuate the response to PAR‐1 agonists, and conversely desensitization to PAR‐1 attenuated the response to thrombin but failed to alter contractile responses to PAR‐2 agonists. The contractile responses produced by thrombin, trypsin, SFLLRN‐NH2 and SLIGRL‐NH2 were markedly reduced in the presence of the cyclo‐oxygenase inhibitor, indomethacin, whilst the small contractile response produced by NRLLFS‐NH2 and LRGILS‐NH2 were insensitive to indomethacin. The contractile responses to thrombin, trypsin, SFLLRN‐NH2 and SLIGRL‐NH2 were unaffected by the presence of: the non‐selective muscarinic antagonist, atropine; the nitric oxide synthase inhibitor, L‐NAME; the sodium channel blocker, tetrodotoxin; the combination of selective tachykinin NK1 and NK2 receptor antagonists, (S)‐1‐[2‐[3‐(3,4‐dichlorphenyl)‐1 (3‐isopropoxyphenylacetyl) piperidin‐3‐yl] ethyl]‐4‐phenyl‐1 azaniabicyclo [2.2.2] octane chloride (SR140333) and (S)‐N‐methyl‐N‐[4‐acetylamino‐4‐phenylpiperidino‐2‐(3,4‐dichlorophenyl)‐butyl] benzamide (SR48968), respectively. The results indicate that PAR‐1 and PAR‐2 activation causes contractile responses in the guinea‐pig gallbladder, an effect that is mediated principally by prostanoid release, and is independent of neural mechanisms.

Bradykinin B2 receptors mediate contraction in the normal and inflamed human gallbladder in vitro

BACKGROUND & AIMS The components of the kinin system, including kinongens, kininogenases, and B(2) and B(1) receptors, are expressed and activated during inflammation. Here, we investigated the expression of the kinin B(2) receptor messenger RNA, kininogen and kallikrein immunoreactivity, and the ability of kinins to contract control and inflamed gallbladders in vitro. METHODS Human gallbladders, obtained from patients undergoing cholecystectomy either for acute cholecystitis secondary to gallstone disease or during elective gastro-entero-pancreatic surgery (controls), were processed for reverse-transcription polymerase chain reaction analysis, kallikrein and kininogen immunohistochemistry, binding studies, and in vitro contractility studies. RESULTS Tissue expression of B(2) receptor messenger RNA and specific binding of [(3)H]-bradykinin increased significantly in acute cholecystitis compared to controls. Kallikrein immunoreactivity was detected in the epithelium and infiltrating leukocytes, whereas kininogen immunoreactivity in the lumen of blood vessels and interstitial space. Bradykinin contracted isolated strips of control and acute cholecystitis gallbladders. In acute cholecystitis tissue, efficacy of bradykinin was higher than that of control gallbladders and similar to that of cholecystokinin. The contraction induced by bradykinin was significantly attenuated by B(2) receptor antagonism but not by cyclooxygenase inhibition and B(1), muscarinic, or tachykinin receptor antagonism. CONCLUSIONS All the components of the kinin system are expressed in the human gallbladder. Bradykinin is a powerful spasmogen via B(2) receptor activation in the normal and, especially, in the inflamed human gallbladder.

Primary rectal lymphoma as a cause of bowel obstruction. Report of a case.

Background Malignant lymphoma involving the rectum either as a localized process or as a manifestation of disseminated disease is rare. Several treatments have been proposed and reported, including surgical resection alone or associated with adjuvant chemoradiation, chemotherapy alone, and radiotherapy alone. Methods A case of bowel obstruction caused by a primary rectal MALT lymphoma is reported. Following emergency loop sigmoid colostomy the patient was started on multiple specific cycles of chemotherapy according to the MACOP-B protocol. Results At the end of chemotherapy a remarkable reduction in the size of the tumor was noted. Subsequently the patient underwent an ultralow anterior resection followed by a straight coloanal anastomosis. At 36 months of follow-up the patient is alive with no tumor recurrence. Conclusions The present report describes the unique case of a patient with primary obstructing rectal lymphoma treated with neoadjuvant chemotherapy and sphincter-saving curative surgery.

Effect of several bicyclic peptide and cyclic pseudopeptide tachykinin NK2 receptor antagonists in the human isolated ileum and colon

The affinities of the monocyclic pseudopeptides MEN10,508, MEN10,573, MEN10,581, MEN10,612, MEN10,619 and MEN10,677, and the bicyclic peptides MEN10,627, MEN10,692, MEN10,771, MEN10,882 and MEN10,993 were evaluated at the tachykinin NK2 receptors of the human isolated ileum and colon circular muscle preparations, by using [betaAla8]neurokinin A(4-10) as an agonist. All of the antagonists tested produced a concentration-dependent and competitive antagonism of [betaAla8]neurokinin A(4-10)-mediated contractions in both preparations. MEN10,612 (pKB = 8.1) and MEN10,627 (pKB = 8.4-8.8) were among the most potent analogs within their chemical classes. In general, the bicyclic peptide antagonists were more potent than the monocyclic peptide compounds, showing a nanomolar affinity for the human NK2 receptor. By comparing the affinities shown by the antagonists under study at NK2 receptors of the human gut with the affinities measured at NK2 receptors of the rabbit isolated pulmonary artery and hamster isolated trachea, a high degree of pharmacological homology was found between human and rabbit NK2 receptors. The present results point out the class of NK2 receptor antagonists bearing a bicyclic peptide structure, like MEN10,627, as candidates for testing in pathological conditions characterized by exaggerated gut motility, in which tachykinins might play a role as non-cholinergic excitatory neurotransmitters.

Radio-guided surgery in recurrent renal hyperparathyroidism: Report of a case

It has been demonstrated that radio‐guided surgery offers several advantages in treating primary hyperparathyroidism. Even if it is considered less helpful in renal hyperparathyroidism, it could be of tremendous advantage in the treatment of persistent or recurrent secondary hyperparathyroidism.