Synthesis and antitumor activity of 2-deamino- and N2-(gamma-hydroxypropyl)actinomycin D

2-Deamino- and N2-(gamma-hydroxypropyl)actinomycin D were synthesized by modification of the parent actinomycin D molecule at the 2 position of the phenoxazinone moiety. The common intermediate was 2-deamino-2-chloroactinomycin D. Catalytic hydrogenation of this material afforded the 2-deamino derivative while treatment with gamma-hydroxypropylamine yielded the N2-(gamma-hydroxypropyl) derivative. These 2-substituted actinomycin D derivatives were less potent in microbiological assays than the parent compound. Evaluation of activity in vivo against three murine tumor systems indicated that optimal dose levels of 2-deaminoactinomydin D were 50 times greater than toxic dose levels of actinomycin D. N2-(gamma-hydroxyporpyl)actinomycin D exhibited antitumor activity similar to the parent compound.

The immunological integrity of matrix substance A and its possible detection and quantitation in urine

There would seem to be no doubt that most stone-forming patients at some time during the course of their disorder excrete substances not present in normal urine. However, considerable doubt must now exist that "Matrix Substance A" is a single antigenic entity or that its presence is confined to the active formation of renal calculi.

New rapid method for diagnosis of deep venous thrombosis

The plasma concentration of the platelet-specific protein beta-thromboglobulin was measured in fourteen patients who had been investigated for deep venous thrombosis by venography or 125I-fibrinogen scanning. All six patients with a proven thrombus had a raised plasma concentration of beta-thromboglobulin. Eight patients in whom no thrombus could be demonstrated had plasma concentrations of beta-thromboglobulin similar to a control group of thirty-five normal individuals. These results indicate that the measurement of plasma beta-thromboglobulin concentrations may be of use in the diagnosis of deep venous thrombosis.

Endothelial injury induced by thrombin or thrombi

A variety of blood constituents was injected into an isolated segment of rabbit aorta to determine which elements might be involved in early endothelial injury. Test materials consisted of platelet-rich plasma (PRP) alone; PRP plus adenosine diphosphate (ADP); PRP plus tendon extract; PRP plus thrombin; ultrasonicated PRP alone; platelet-poor plasma alone; and thrombin in saline. Each experimental mixture was left in the aorta for 15 minutes, followed by reflow for 20 minutes. The vessel was then fixed by glutaraldehyde perfusion. Thick sections of the entire circumference of the aorta were taken for phase contrast microscopy and representative arease were selected for electron microscopy. In control PRP alone, platelet-poor plasma alone and with PRP plus ADP there were occasional subendothelial vesicles. When PRP plus thrombin and platelet-poor plasma plus thrombin were injected separately to form a thrombus or when thrombin in saline was used, there was extensive subendothelial vesiculation with focal ulceration and adherence of thrombus to endothelium. Severe injury was associated with the presence of thrombin initiating the polymerization of fibrinogen to fibrin. Electron micrographs demonstrate the earliest lesion as a disruption of the superficial fibrilliary elastica with separation of overlying endothelium.

National Conference on Thrombosis and Hemostosis, Dallas, Tesas 20.-22. November 1974. Clinical Correlations

There are two aspects which are clinically relevant in the relationships among thrombosis and arteriosclerosis. First, the relationship of thrombosis to atherogenesis. Thrombosis is closely related to endothelial injury and there is recent evidence that repeated or continuous endothelial damage leads to the development of all the lesions seen in human atherosclerosis. This occurs in the absence of dietary lipid supplement. The relative importance of the parts played by injury and thrombosis in this process need further delineation. Secondly, established arteriosclerotic disease is associated with thrombosis. This thrombosis is us ually mural, seldom occlusive. Embolism by platelet aggregates which has been well described in the retinal and cerebral circulations may affect other vascular territories such as the heart and the kidney. Such a mechanism may explain some cases of otherwise unexplained sudden cardiac death and some cases of hypertension. We need better clinical tool to detect the occurrence of thrombo-embolism and to monitor it's progress. Measures to modify thrombosis and embolism may be as useful or more useful than those wer currently employ in the clinical management of atherosclerotic disease.

Solubilization of 2',3'-cyclic nucleotide 3'-phosphohydrolase from bovine brain without detergents

The enzyme in brain that hydrolyzes 2',3'-cyclic nucleotides to the 2'-mononucleotides has been found by several authors to be concentrated in the myelin fraction. To facilitate further study of the enzyme, one of our objectives has been to develop a method of solubilizing the enzyme without the use of detergents. When an acetone powder from brain white matter is homogenized with 1 M guanidinium chloride in 0.2 M buffer at pH 6, 10(-3) M in EDTA and in dithiothreitol, the enzyme is solubilized. If the guanidinium chloride is removed by dialysis in a single step, the enzyme reprecipitates, but if a fractional precipitation is performed by reducing the guanidinium chloride concentration by dilution, the enzyme remains in solution at 0.2 M guanidinium chloride. The precipitates obtained in this fractionation probably contain constituents which, at low salt concentration, formed a part of an insoluble aggregate, since after removal of the pellet the supernatant solution can be dialyzed free of guanidinium chloride without precipitating the enzymic activity. The enzyme thus prepared remains in the supernatant when centrifuged at 108,000 X g for 3 h and can be submitted to (NH4)2SO4 fractionation and chromatography on carboxymethyl-Sephadex and on hydroxylapatite. The enzyme has thereby been purified 200-fold in about 20% yield.

Repeated endothelial injury and induction of atherosclerosis in normolipemic rabbits by human serum

Since Duguid suggested that atherosclerosis represents essentially the organization of mural thrombi, there have been many attempts to produce the disease experimentally by damaging the arterial wall. A single injury to the inner lining of an artery causes lipid-free lesions, composed of smooth muscle cells and collagen, covered by endothelium. Previously, we reported the development of atherosclerotic lesions in normolipemic rabbits as a result of repeated or continuous intimal injury by an indwelling aortic polyethylene catheter. However, it was difficult to control the location or duration of the intimal injury. The present investigation was designed to produce repeated endothelial injury in a defined segment of rabbit carotid artery. Sixty-two rabbits received injections of either lymphocytotoxic-positive (LP) or lymphocytotoxic-negative (LN) human serum into a segment of left carotid artery. Autologous rabbit serum was injected into the right carotid artery as a control. Eight rabbits received a single injection of LP and were killed 4 weeks latermforty-two rabbits received injections of human serum at weekly intervals, for a maximum of four injections, and were killed 1 week after the last injectionmthirty-two of 42 rabbits received repeated injections of LP; 10 received repeated injections of LN. Raised, lipid-containing lesions were present in 21 of 26 rabbits receiving four repeated injections of LP. No, or very minimal (fewer than three cells thick), intimal thickening was found in the 10 LN rabbits and in all control right carotid arteries. In eight rabbits receiving one injection of LP, fibrous intimal thickening without lipid accumulation, fatty streaks, and edematous plaques were found. Electron microscopy of arteries from 12 rabbits sampled at 1,5, and 60 minutes after exposure to LP indicated that the initial damage was loss of endotheliummthe results consistently showed lipid in raised, thrombus-covered (non-reendothelialized) lesions. Nonraised, endothelialized lesions did not show lipid. These findings support the belief that atherosclerosis occurs in response to repeated endothelial injury.

The isolation and characterisation of a platelet-specific beta-globulin (beta-thromboglobulin) and the detection of antiurokinase and antiplasmin released from thrombin-aggregated washed human platelets

A protein fraction was isolated from the supernatant of thrombin-aggregated washed human platelets and was shown, by immunodiffusion techniques, to contain a platelet-specific beta-globulin (beta-thromboglobulin) as the major component. A molecular weight of 35 800 was determined for beta-thromboglobin from the measured sedimentation coefficient of3.0 S and Stokes radius of 2.85 nm. Beta-Thromboglobin was detected in the serum from whole blood and the supernatant of 48-h-old platelet-rich plasma and 28-day-old citrated whole blood, but not in platelet-poor plasma. The fraction containing beta-thromboglobulin was shown to possess an antiurokinase activity but was devoid of antiplasmin activity. A further fraction of approximate molecular weight 70 000 was also isolated which contained an antiplasmin but was devoid of antiurokinase activity.

Platelet antiheparin activity. The isolation and characterisation of platelet factor 4 released from thrombin-aggregated washed human platelets and its dissociation into subunits and the isolation of membrane-bound antiheparin activity

Platelet factor 4 was isolated by gel filtration from the soluble release products of thrombin-aggregated washed human platelets as a proteoglycan-platelet factor 4 complex of molecular weight 358 000, Stokes radius (r-s) of 14.0 nm, sedimentation coefficient (s) of 7.1 S and frictional ratio (f/f-o) of 3.04. The complex was dissociated at high ionic strength (I equals 0.75) and the proteoglycan separated from platelet factor 4 by gel filtration. Platelet factor 4 had a molecular weight of 27 100, r-s of 2.52 nm, s of 2.4 S and f/f-o of 1.26, was insoluble under physiological conditions but readily soluble at pH 3. Under these conditions platelet factor 4 dissociated into four subunits with a molecular weight of 6900, r-s of 1.92 nm, s of 0.8 S, and f/f-o of 1.52. Qualitative N-terminal amino acid analysis showed the presence of glutamic acid or glutamine as the major end group. Platelet factor 4 was compared with protamine sulphate, which has similar biological properties, by electrophoresis at pH 2.2, in which both migrated as single bands but with differing mobility, and by amino acid analysis which showed a more normal distribution of residues than occurred in protamine sulphate. Of the basic amino acids platelet factor 4 (molecular weight 27 100) contained 5.97% arginine, 3.18% histidine, and 12.31% lysine compared to protamine sulphate with 64.2% arginine, 0.6% lysine and no histidine. A partial specific volume (v) of 0.747 was calculated for platelet factor 4 from its amino acid analysis. A membrane fraction with antiheparin activity, an isopycnic density of 1.090-1.110 and r-s of 15-35 nm, was also isolated by sucrose density gradient centrifugation from the ultrasonicated insoluble platelet residue remaining after thrombin-induced aggregation of washed human platelets. Trypsin treatment of the membrane fraction neither solubilised nor destroyed the activity.

Social position and competition in laboratory rats

Two experiments with rats as subjects are described, which control for social position, i.e., relative dominance/submission, in an appetitive social learning-performance setting. The results indicate that animals that perform quite effectively when alone exhibit significantly reduced levels of responding when placed into a social environment. The severity of the response decrement is, at least in part, a function of the relative social position of the subjects involved. A dominant male made few responses when paired with another dominant male. Yet, a dominant subject made even fewer responses when paired with a submissive subject, which bar pressed at approximately half the individual level. These findings are interpreted as suggesting that social position, with its accompanying characteristic form of aggression, is an important determinant of performance in a social learning environment.

Pancreatic ribonuclease: enzymic and physiological properties of a cross-linked dimer

Monomeric ribonuclease A has very low activity toward typically double-stranded RNA's; the dimeric form of ribonuclease A obtained by cross linking the enzyme by dimethyl suberimidate has more than 78 times the activity of the monomer toward polyadenylate . polyuridylate and 440 times the activity of the monomer toward the double-stranded RNA of a virus from Penicillium chrysogenum. The half-life of the dimer in the bloodstream of the rat is 12 times that of the mononmer.

Lipid composition and metabolism of thromboatherosclerotic lesions produced by continued endothelial damage in normal rabbits

Thromboatherosclerotic and fibrous lesions were produced by endothelial damage with polyethylene catheters inserted into the aortas in rabbits on a normal diet. Two weeks after insertion of the catheters, the concentration of both free cholesterol and cholesteryl ester in the thromboatherosclerotic lesions was significantly greater than that in the adjacent normal intima. A further increase in the concentration of free cholesterol and particularly of cholesteryl ester occurred during the remainder of the 4-month study period. Gas-liquid chromatography indicated that the raised thromboatherosclerotic lesions contained more cholesteryl oleate and less cholesteryl linoleate than did either the normal intima or the fibrous lesions. The incorporation of [1 -14 C] oleic acid into combined lipid in the aortas incubated in vitro showed that, by 2 weeks, two to three times more oleic acid had been incorporated into cholesteryl ester in the thromboatherosclerotic raised lesions than in the normal intima. A similar increase was demonstrated at 2 and 4 months. When [ 32 P] phosphate was used as a precursor, incorporation into lecithin was higher and incorporation into phosphatidyl inositol was lower in the raised lesions than they were in the normal intima. Fibrous lesions did not differ significantly from the adjacent normal intima in their incorporation of either of these precursors into lipid. Therefore, the accumulation of cholesteryl ester in the thromboatherosclerotic lesions resulted in part from synthesis in the arterial wall, which was stimulated by the prominent platelet components of the lesions.