Evidence for the presence of functional protease activated receptor 4 (PAR4) in the rat colon

BACKGROUND AND AIMS

Protease activated receptors (PARs) have been postulated to play a role during intestinal inflammation. The presence and role played by PAR(4) in gastrointestinal functions have not been fully clarified. The aims of this study were: (i) to examine expression of PAR(4) in rat proximal colon; (ii) to determine the mechanical effects induced by PAR(4) activation in longitudinal muscle; and (iii) to characterise the underlying mechanisms.

METHODS

PAR(4) expression was determined by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. Mechanical activity was recorded as changes in isometric tension.

RESULTS

A PCR product corresponding to the predicted size of the PAR(4) signal was amplified from RNA prepared from the colon of rats, showing the presence of PAR(4) in those tissues. Immunohistochemistry revealed that PAR(4) protein was expressed on epithelial surfaces and submucosa. PAR(4) activating peptides, GYPGKF-NH(2) and AYPGKG-NH(2), produced concentration dependent contractile effects on longitudinal muscle. Tetrodotoxin (TTX) or atropine significantly reduced the contractile responses to AYPGKG-NH(2), and atropine after TTX did not cause any further reduction. NK(1) receptor antagonist, SR140333, or NK(2) receptor antagonist, SR48968, alone or in combination, produced a reduction in PAR(4) induced contractile effect, and when coadministered with TTX abolished it. Capsaicin markedly reduced the contractions evoked by AYPGKG-NH(2).

CONCLUSIONS

The present results suggest that PAR(4) is functionally expressed in rat colon and its activation induces contraction of the longitudinal muscle both through TTX sensitive release of acetylcholine and release of tachykinins, probably from sensory nerves. These actions may contribute to motility disturbances during intestinal trauma and inflammation.

[Use of the economic evaluation in the comparison of different vaccination programs against Haemophilus influenzae type b disease]

Although economic evaluation offers a relevant contribution to the health policy's choices, only few studies appeared so far on its application to the field of vaccinations. The present study compares several hypotheses of vaccination strategies in order to evaluate the opportunity to introduce a vaccination program against Haemophilus influenzae b infection. The vaccination strategies are evaluated in terms of costbenefits, cost-effectiveness and cost-utility. The results show that the highest benefits could be obtained performing mass vaccination in the age-group 0-5 years. Actually this hypothesis, compared to other, offers the best compliance and externalities; furthermore it has the highest ethical value.

[Visceral leishmaniasis in Italy. Its epidemiology, clinical picture and therapy]

Visceral leishmaniasis (VL) is a public health problem in most countries bordering the Mediterranean sea. The disease has been found in central and southern Italy, Sicily, Sardinia; some pockets are present in Liguria. Dogs are the reservoirs and the vectors are some species of sandfly (Phlebotomus species). The incubation period is usually between 2 and 8 months; children and adults may become infected; lethality may be high and depends upon a correct diagnosis and treatment. The diagnosis should be suspected on the basis of the epidemiological data and clinical picture and confirmed by the detection of specific antibodies by appropriate techniques. Leishmaniasis can be detected in splenic or bone marrow aspirates. Patients with HIV infection and VL may lack specific antibodies; parasitological diagnosis is mandatory for these patients. Antimonials are the classic therapeutic agents for VL. Recently liposomal amphotericin B (Ambisome) has been successfully used, with negligible toxicity.

The epidemiology and surveillance of visceral leishmaniasis in the Campania region of Italy. The value of zymodeme typing

Although human visceral leishmaniasis (VL) is a notifiable disease in Italy, there is evidence that the actual number of cases is far higher than that notified. A programme for active surveillance of VL in the 14 Italian endemic regions was launched by the Istituto Superiore di Sanità. We report data collected during a 3-year period of active surveillance in Campania, a south Tyrrhenian region covering 4.5% of the Italian territory. Out of 120 clinically suspected cases referred to medical and diagnostic references centres, there were 52 confirmed VL cases (17.3/year), i.e. 10-fold more than previously notified. Most of the infection sites were in rural areas or peripheral districts of towns in hilly parts of Naples province. An epidemic cluster of 10 cases was identified in a microfocus of Caserta province. The biochemical analysis of 23 Leishmania stocks showed a zymodeme composition indicating Campania as an old and well-established focus of VL. The data obtained emphasize that the present notification system for VL in Italy is inadequate.