The goal of the study was to perform a detailed anatomical description of the retrocalcaneal bursa (RB). Its morphological arrangement was studied on 10 fresh and 30 embalmed lower extremities by microdissection and light microscopy. The RB was present constantly and in all the cases contained 1-2 cm long synovial fold, beginning on the upper wall of RB and distally interposed between the anterior surface of the Achilles tendon and the posterior surface of the calcaneal tuberosity. The volume of RB was 1-1.5 ml. The histological analysis confirmed that the inner surface of the superior and posterior wall of RB have been covered by unilayered synovial membrane, projecting into synovial villi of different shapes and sizes. In the ceiling of RB, delicate fascicle of skeletal muscle fibers was discovered, radiating distally into the regularly present synovial fold. The whole bottom of RB has been covered by 200-500 microm layer of fibrous cartilage into which the calcaneal tendon attached. The cartilagineous layer continued anteroproximally to cover the whole bursal surface of the calcaneal tuberosity, where the thickness of the cortical bone was reduced on mere 50 microm. The obtained results can be used in the improvement of the differential diagnostics and therapy of diagnostics and therapy of the retrocalcaneal bursitis as well as of other kinds of achillar enthesopathies and heel pain.
The kinetics and mechanism of the acid-catalysed hydrolysis of substituted 4-alkyl-4-methyl-2-aryl-4,5-dihydro-1,3-oxazol-5-ones to the corresponding 2-alkyl-2-benzoylaminopropanoic acids were studied. The Taft correlation of rate constants of the acid-catalysed hydrolysis with alkyl substitution at the 4-position of the 1,3-oxazol-5-one ring is non-linear. In the Hammett correlation, the value of decreases with increasing steric demand of the alkyl substituent. With the 4-isopropyl and tert-butyl derivatives, ¼ À0.63 and À0.32, respectively. The protonated 4-isopropyl and tert-butyl derivatives undergo nucleophilic attack by water at the carbonyl carbon atom at the 5position of the 1,3-oxazol-5-one ring to the extents of ca 70% and 60%, respectively. Another reaction path consists in nucleophilic attack by water at the 2-position of the 1,3-oxazol-5-one ring. The reaction kinetics of aminolyses of substituted 4-isopropyl-4-methyl-2-phenyl-1,3-oxazol-5(4H)-ones (1a, 1b, 1f) giving substituted N-{1,2-dimethyl-1-[(propylamino)carbonyl]-propyl}benzamides (3a, 3b, 3f, 4a) was studied in aqueous propylamine buffers. In the case of the aminolysis of 1a and 1b with propylamine, the rate-limiting step consists in the decomposition of the intermediate In AE catalysed by both the acidic and the basic buffer components. The base-catalysed route is four times faster in both cases. In the case of the aminolysis of 1f with propylamine and that of 1a with ethylenediamine, the ratelimiting step is the formation of the intermediate In AE , the subsequent reaction step being accelerated by substitution and/or intramolecular catalysis.
EXPERIMENTAL MaterialsThe new dialkyl-2-aryl-4,5-dihydro-1,3-oxazol-5-ones were prepared by a known method 11 of ring closure and
A series of substituted 5-, 6-, 7-, and 8-hydroxy-3-phenyl-2H-1,3-benzoxazine-2,4(3H)-diones (5-8) was synthesized by cyclization of corresponding dihydroxy-N-phenylbenzamides (1-4) with methyl chloroformate. The starting compounds 1-4 were prepared by the reaction of the respective dihydroxybenzoic acid, aniline and phosphorus trichloride via microwave irradiation. Thionation of compounds 8a-d employing Lawesson's reagent was used to prepare 5-hydroxy-3-phenyl-4-thioxo-3,4-dihydro-2H-1,3-benzoxazin-2-ones (10a-d) and 5-hydroxy-3-phenyl-2H-1,3-benzoxazine-2,4(3H)-dithiones (11a-d). The position of sulfur in monothionated derivatives 9c and 10a-d was confirmed by 2D NMR methods. Attempts to prepare dithionated derivatives from the isomeric 6-, 7-or 8-hydroxy compounds 5-7 failed. All compounds were tested for their in vitro antifungal activity against eight test strains. Compounds 1-4 showed moderate activity and the cyclization to corresponding hydroxy-3-phenyl-2H-1,3-benzoxazine-2,4(3H)-diones (5-8) resulted in a decrease in antifungal activity. No antifungal activity was observed in thionated compounds 9c and 10-11.
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