Structural studies on minor components of saframycin group antibiotics saframycins F, G and H

Three minor components of saframycin group antibiotics, saframycins F, G and H were isolated and their structures were determined by comparison with the spectral data of UV, IR, and 1H and 13C NMR of already reported saframycins A and D. Saframycins F, G and H were 21-cyanosaframycin D, 14-hydroxysaframycin A and 25-dihydro-25-beta-ketopropyl-saframycin A, respectively.     

Absorbed dose comparison among commercial ionization chambers in polystyrene and acrylic phantoms

Using the AAPM Task Group 21 protocol, photon and electron doses were compared in polystyrene and acrylic phantoms. The ionization chambers used were a Farmer graphite chamber, a PTW acrylic chamber, a homemade polystyrene chamber, and an Exradin air-equivalent chamber, all being of cylindrical type. A Memorial parallel-plate polystyrene chamber was also included. 60Co, 4-, 6-, and 18-MV x rays as well as 9- and 20-MeV electron beams were investigated.     

Inhibition of thromboxane A2-induced vasocontraction by KF4939, a new anti-platelet agent, in rabbit mesenteric and dog coronary arteries

The effect of a new anti-platelet agent, KF4939, on thromboxane A2 (TXA2)-induced vasocontraction was studied in superfused rabbit mesenteric and dog coronary arteries, in comparison with the effects on the contractions evoked by KCl, noradrenaline, serotonin, angiotensin II and histamine. The calcium sources involved in the TXA2-induced vasocontraction were also examined. The TXA2-induced contraction of the rabbit mesenteric artery was partly attenuated after exposure to the calcium-free medium, but was not attenuated by nifedipine. The TXA2-induced contraction of the dog coronary artery was markedly attenuated by nifedipine. These results indicate that TXA2 utilizes both intracellularly stored calcium and an extracellular source of calcium for its vasocontraction, and the voltage-dependent calcium channel plays an important role in the dog coronary artery, but in the rabbit mesenteric artery. KF4939 inhibited the TXA2-induced contraction in both arteries. In the rabbit mesenteric artery, three times and more higher concentration than that to inhibit TXA2-induced one were required to inhibit other agonist induced contractions, KF4939 caused no alteration in the KCl-induced contraction of both arteries. Thus, KF4939 seems to be a selective inhibitor of TXA2-induced vasocontraction, and the receptor-linked mechanism may be a possible site of the TXA2 antagonistic action of KF4939.     

A method for production of antibodies to human T-cell receptor beta-chain variable regions.

Mouse T-cell hybridomas bearing human V beta elements were produced by transfection of human/mouse hybrid T-cell receptor beta-chain genes into a mouse T-cell hybridoma lacking an endogenous beta-chain gene. These hybridomas were entirely mouse in origin except for the human V beta region. These cells were used to immunize mice against human V beta elements. Mouse monoclonal antibodies have thus been generated against human V beta 13.1 and -13.2. We expect that the method outlined in this paper will be useful in the production of monoclonal antibodies specific for other human V beta or V alpha elements.     

Wall reinforcement with highly porous Dacron mesh in aortic surgery.

Wall reinforcement with highly porous synthetic Dacron mesh was devised and evaluated in various aortic operations. Excellent attachment of the mesh to the aortic wall, good preservation of pliability of the aorta, and efficient pressure resistance with minimal scar tissue formation were the usual findings. This type fo wall reinforcement was employed in 60 patients for the following indications: 1) prevention of suture line complications; 2) wall reinforcement of aortic aneurysm without resection; 3) reinforcement of adventitia or autogenous vein following thromboendarterectomy. It is concluded that reinforcement with highly porous synthetic Dacron mesh should be superior to reinforcement with conventional prosthetic Dacron graft.