Non-peptide GPIIb/IIIa inhibitors. 20. Centrally constrained thienothiophene alpha-sulfonamides are potent, long acting in vivo inhibitors of platelet aggregation.

The synthesis and pharmacology of 4, a potent thienothiophene non-peptide fibrinogen receptor antagonist, are reported. Compound 4 inhibited the aggregation of human gel-filtered platelets with an IC50 of 8 nM and demonstrated an 8-fold improvement in affinity for isolated GPIIb/IIIa receptors over analogues possessing an isoindolinone backbone. Flow cytometry studies revealed that the binding of 4 to resting platelets is a diffusion-controlled process (kon = 3.3 x 10(6) M-1 s-1) and that 4 binds to dog and human platelets with comparable affinity (Kd = 0.04 and 0.07 nM, respectively). Ex vivo platelet aggregation in dogs was completely inhibited by an iv dose of 5 microg/kg [corrected], and an oral dose of 50-90 microg/kg [corrected] followed by low daily doses of 10 microg/kg [corrected] was sufficient to maintain approximately 80% inhibition of ex vivo platelet aggregation over several days. Inhibition of ADP-induced platelet aggregation in anesthetized dogs at 77 +/- 7% resulted in a moderate 2.5-fold increase in bleeding time, while complete inhibition (100%) resulted in an approximately 10-min bleeding time. Additional doses were required to increase the bleeding time to the maximum time allowed in the protocol (15 min), thus indicating a potentially useful and safe separation of efficacy and bleeding time.

A service manager model: instituting case management.

Using a service manager model as opposed to a traditional nurse case manager archetype fosters multidisciplinary team interaction. Benefits of this approach to the hospital, the staff and the patients are identified.

Role of hyaluronic acid in the in vivo aggregation of cartilage proteoglycans.

From studies of isolated cartilage proteoglycans in solution it has been inferred that they occur in the tissue as aggregates of high molecular weight which consist of proteoglycan monomers, hyaluronic acid and specific link proteins. The present investigation provides direct evidence for the existence of hyaluronic acid-containing aggregates in vivo, as indicated by the following observations: Treatment of sections of coastal cartilage from newborn rabbits with Streptomyces hyaluronidase led to complete disappearance of the electron dense granules, which have been previously identified as chondroitin sulfate proteglycans, from the extracellular matrix. Similar results were obtained on digestion with leech hyaluronidase which, like the Streptomyces enzyme, specifically degrades hyaluronic acid. Proteoglycan aggregation occurs not only in the extracellular compartment but intracellularly as well, since a portion of the hyaluronidase-senstive, electron dense proteoglycan granules are found in intracellular vesicles. It is concluded that the ability of proteoglycan monomers to form aggregates is a true reflection of the in vivo organization of these molecules and that aggregate formation is an important factor in the maintenance of the normal physiological function of cartilage tissue.