Ramatroban (BAY u 3405): A Novel Dual Antagonist of TXA2 Receptor and CRTh2, a Newly Identified Prostaglandin D2 Receptor

It is known that thromboxane A₂ (TXA₂) contributes to various diseases such as bronchial asthma, ischemic heart disease, cerebrovascular disorders and allergic rhinitis. A number of TXA₂ synthase inhibitors and TXA₂ receptor (TP receptor) antagonists have been developed to treat these diseases. Ramatroban (BAY u 3405) was developed as a potent TP receptor antagonist with excellent efficacy against allergic rhinitis in many animal models and patients. Recent studies also revealed that ramatroban can block the newly identified PGD₂ receptor, chemoattractant receptor‐homologous molecule expressed on Th2 cells (CRTh2). PGD₂ induces migration and degranulation of eosinophils through CRTh2 and contributes to late‐phase inflammation and cell damage. Accordingly, it was considered that ramatroban suppresses the late‐phase inflammation via TP receptor and CRTh2 blockade. In terms of the efficacy on vascular systems, it was revealed that ramatroban can suppress the expression of monocyte chemoattractant protein‐1 (MCP‐1) and adhesion molecules in endothelial cells and prevent exacerbation of inflammation by blocking these responses. According to our recent studies in hypercholesterolemic rabbits ramatroban prevents macrophage infiltration through MCP‐1 downregulation and neointimal formation after balloon injury and attenuates vascular response to acetylcholine. Therefore, ramatroban may be beneficial in the treatment of atherosclerosis.     

Pharyngeal Patency in Response to Advancement of the Mandible in Obese Anesthetized Persons

Background: During anesthesia in humans, anterior displacement of the mandible is often helpful to relieve airway obstruction. However, it appears to be less useful in obese patients. The authors tested the possibility that obesity limits the effectiveness of the maneuver.

Methods: Total muscle paralysis was induced under general anesthesia in a group of obese persons (n = 9; body mass index, 32 +/- 3 kg sup -2) and in a group of nonobese persons (n = 9; body mas index, 21 +/- 2 kg sup -2). Nocturnal oximetry confirmed that none of them had sleep-disordered breathing. The cross-sectional area of the pharynx was measured endoscopically at different static airway pressures. A static pressure-area plot allowed assessment of the mechanical properties of the pharynx. The influence of mandibular advancement on airway patency was assessed by comparing the static pressure-area relation with and without the maneuver in obese and nonobese persons.

Results: Mandibular advancement increased the retroglossal area at a given pharyngeal pressure, and mandibular advancement increased the retropalatal area in nonobese but not in obese persons at a given pharyngeal pressure.     

Avidity of technetium 99m glucarate for the necrotic myocardium: In vivo and in vitro assessment

Background  Similar to other^99mTc-based infarct-avid agents,^99mTc-glucarate localizes in myocardial infarcts. Whether severely ischemic viable myocytes sequester^99mTc-glucarate is uncertain. To assess the infarct specificity, in vitro and in vivo studies were performed. Methods and Results  H9C2 embryonic rat cardiocytes cultured under normoxia (N) or hypoxia (H) for 24 hours in 7.5 μCi^99mTc-glucarate were compared with necrotic cardiocytes. Mean H/N ratio (3.0±0.004, mean±SD) was significantly less than that of the necrotic/N ratio (39.9±6.5,p<0.01). Reperfused myocardial infarction (MI) in 4 dogs confirmed by²⁰¹Tl, (0.5 to 1.0 mCi) scintigraphy were imaged serially, with simultaneously injected mixture of^99mTc-glucarate and¹¹¹In-antimyosin Fab. Infarcts were detected scintigraphically within 4 to 10 minutes with^99mTc-glucarate.¹¹¹In-antimyosin required more than 1 hour. Myocardial distribution at 5 hours showed a direct correlation between^99mTc-glucarate and¹¹¹In-antimyosin uptake (r=0.99,p<0.0001). Both^99mTc-glucarate (r=−0.777,p<0.0001) and¹¹¹In-antimyosin (r=−0.775,p<0.0001) were inversely related to²⁰¹Tl distribution. Conclusions  The near perfect correlation between^99mTc-glucarate and¹¹¹In-antimyosin uptake (r=0.99) in reperfused canine MI and the insignificant glucarate uptake by viable cardiocytes in vitro attest to the avidity of^99mTc-glucarate for the necrotic myocardium and favor its use as a specific early marker of myocyte necrosis in acute MI. Supported in part by SBIR grant 1R43-HL54410-01 and Molecular Targeting Technology, Inc.