Histamine-enhanced contractile responses of gastric smooth muscle via interstitial cells of Cajal in the Syrian hamster

BACKGROUND

Gastric motility is controlled by the autonomic and enteric nervous systems and by interstitial cells of Cajal (ICCs). Although histamine is known to be released from enterochromaffin-like cells in the gastric mucosa, its regulatory roles in gastric motility are still controversial. Therefore, we investigated the functional roles of histamine in gastric motility.

METHODS

Stomach preparations from hamsters were used because the stomach of hamsters can be easily separated into the forestomach and the glandular stomach. A whole preparation of the stomach was mounted in a Magnus tube, and mechanical responses were recorded using a force transducer.

KEY RESULTS

Exogenous application of histamine had little effect on contractile activity of the glandular stomach. In contrast, the monoamine evoked regular, periodic contractions in the forestomach. An H1 receptor agonist reproduced the contractile responses and an H1 receptor antagonist blocked histamine-evoked contractions. Atropine and tetrodotoxin did not affect the histamine-evoked contractions. Pretreatment with drugs that inhibit the activity of ICCs abolished the effects of histamine.

CONCLUSION & INFERENCES

The findings suggest that histamine regulates gastric motility by acting on ICCs via H1 receptors in the hamster. The remarkable ability of histamine to induce rhythmic contractions would be useful for treatment of gastric dysmotility.

Thrombotic risk stratification by platelet count in patients with antiphospholipid antibodies: a longitudinal study

Essentials Thrombotic risk stratification is an unmet need in antiphospholipid antibody carriers. Platelet count and antiphospholipid score (aPL-S) were combined to predict thrombotic events. Patients with high aPL-S are at high thrombotic risk regardless of platelet count. If platelet count is low, patients with low aPL-S are also on high thrombotic risk.

SUMMARY

Background Thrombocytopenia is a non-criteria clinical manifestation of antiphospholipid syndrome. However, it remains to be elucidated whether thrombocytopenia increases thrombotic risk in antiphospholipid antibody (aPL) carriers. Objectives To investigate the impact of platelet count in terms of predicting thrombotic events in aPL carriers, and to stratify the thrombotic risk by combining platelet count and antiphospholipid score (aPL-S), which represents a quantification of aPL varieties and titers. Patients/methods A single-center, retrospective, longitudinal study comprising 953 consecutive patients who were suspected of having autoimmune disease between January 2002 and December 2006 was performed. Low platelet count was defined as a count of < 150 × 103 μL-1 at the time of aPL testing. Results A negative correlation was observed between aPL-S and platelet count (r = - 0.2477). Among aPL-positive patients, those with a low platelet count developed thrombosis more frequently than those without (hazard ratio [HR] 2.95, 95% confidence interval [CI] 1.11-7.88). Among aPL-negative patients, no difference was found in the predictive value of thrombosis regardless of platelet count. Patients with aPLs were further divided into two subgroups according to aPL-S. Among low-aPL-S patients, those with low platelet counts developed thrombosis more frequently than those without (HR 3.44, 95% CI 1.05-11.2). In contrast, high-aPL-S patients developed thrombosis frequently regardless of platelet count. Conclusions aPL carriers with low platelet counts are at high risk of developing thrombosis. In particular, 'low-aPL-S carriers' may be stratified by platelet count in terms of predicting future thrombotic events.