The anti-proteolytic behavior of lathyrogens

The lathyrogens, beta-aminopropionitrile and alpha-aminoacetonitrile inhibit both the esterolytic and proteolytic activity of trypsin at a concentration of 100 mM. Lineweaver-Burk plots demonstrate that inhibition is competitive, with alpha-aminoacetonitrile being the more potent inhibitor. The enzyme associated with and capable of digesting tropoelastin is inhibited by both lathyrogens when tested against its natural substrate, tropoelastin. Administration of alpha-aminoacetonitrile-HCl to the diet of young chicks (0.1% w/w) resulted in a 62% increase in the yield of tropoelastin and significant reduction in fatality as compared to beta-aminopropionitrile-fumarate.

Inhibitors for the mutagenicities of colon carcinogens, 1,2-dimethylhydrazine and azoxymethane, in the host-mediated assay

Inhibitory effects of several chemicals on the mutagenicities of 1,2-dimethylhydrazine (DMH) and azoxymethane (AOM) for Salmonella typhimurium G46 in the host-mediated assay were investigated. They were carbon disulfide (CS2), tetraethylthiuram disulfide (disulfiram, DSF), sodium diethyldithiocarbamate (SDDC), ethylene-bis(dithiocarbamato) manganese (Maneb), pyrazole (PZ), aminoacetonitrile hydrogen sulfate (AAN), and sodium selenite (SE). All the compounds, except for SE, inhibited the mutagenicities of DMH and AOM.

Inhibition of the alkylation of nucleic acids and of the metabolism of 1,2-dimethylhydrazine by aminoacetonitrile

Pretreatment of rats with aminoacetonitrile inhibited the metabolism of [14C]1,2-dimethylhydrazine to 14CO2 and increased the expiration of [14C]-azomethane. Alkylation of nucleic acids following administration of 1,2-dimethylhydrazine was reduced by aminoacetonitrile to 5% of control levels in liver, 11% of control levels in kidney and 43% of control levels in colon.

Reversible decrease of collagen crosslinking by protein low diet and aminoacetonitrile--effect of D-penicillamine and prednisolone on the rise of crosslinks

After ending a 4-week period of low-protein diet with or without aminoacetonitrile (AAN), the tail tendons of rats showed an increase of hydroxylysinonorleucine (HLNL) together with other unidentified reducible crosslinks. The binding of dihydroxylysinonorleucine type (DHLNL) was an exception: its content remained unchanged. It may be, assumed, therefore, that the procedures mentioned above act indiscriminately against all reducible crosslinks with the exception of DHLNL. The rise in crosslinks after the 4-week pretreatment was disturbed, when d-penicillamine was given, because it specifically inhibited the formation of HLNL. The content of other crosslink components was slightly increased above that of controls so that the absolute content of total isolated crosslinks increased in the presence of d-penicillamine. No statistically significant differences could be obtained under prednisolone.

Inhibition of dimethylnitrosamine-induced strand breaks in liver DNA and liver cell necrosis by diethyldithiocarbamate

Diethyldithiocarbamate (DEDTC) prevented dimethylnitrosamine (DMN)-induced strand breaks in liver DNA and liver cell necrosis in male Wistar rats. In contrast, DEDTC did not inhibit the fragmentation of liver DNA caused by several other chemical carcinogens (N-hydroxy-2-acetylaminofluorene, 3-hydroxyxanthine, aflatoxin B1, N-acetoxy-2-acetylaminofluorene, methyl methanesulfonate, methylnitrosourea, and methylazoxy-methanol acetate), whether or not they required metabolic activation. Aminoacetonitrile exerted an action similar to that of DEDTC. The inhibitory effect was transitory, lasting at least for 4 hours, and protection for longer than 4 hours required multiple administrations of DEDTC. DEDTC also inhibited the serum clearance of DMN, methylation of liver DNA, and oxidative demethylation of DMN in the in vitro hepatic microsomal system prepared from either male Wistar rats or from hamsters. Interference of the metabolism of DMN appeared to be the mechanism by which DEDTC arrested DMN-induced biochemical and biologic effects.

The effect of aminoacetonitrile on calcium metabolism and bone in the rat

1. The effect of the osteolathyrogen aminoacetonitrile (AAN) on plasma calcium, phosphate and alkaline phosphatase, on bone, on growth rates, on absorption of calcium and phosphate in the gut and on their urinary excretion, has been examined in rats. 2. AAN caused a general deterioration in the health of the rat and reduced its rate of growth. 3. AAN reduced plasma calcium and increased plasma alkaline phosphatase but did not affect plasma phosphate. 4. AAN caused obvious deformity of the long bones with large exostoses. The femurs of the lathyritic rats had an increased fat-free weight and increased fat-free weight to ash weight ratio. 5. AAN increased true and apparent absorption of calcium but did not consistently affect urinary excretion of phosphate or apparent absorption of phosphate. 6. AAN did not produce a significant reduction in the plasma calcium of parathyroidectomized or thyroparathyroidectomized rats. 7. Absorption of calcium from ligated jejunal loops was increased in AAN-treated parathyroidectomized rats. 8. In some experiments parathyroidectomy or thyroparathyroidectomy protected the bones from the effect of AAN.

Effect of a lathyrogen (aminoacetonitrile hydrochloride) on aortic physiosclerosis and skeletal mineralization in growing rats of different age

In one experiment, four groups of six-week-old-male PVG rats were, respectively, given tap water ('control group'), 0.00125M, 0.0025M, and 0.005M lathyrogen (aminoacetonitrile hydrochloride: AAN) solutions ad libitum for a period of 20 weeks. In a second experiment, 12-week-old male rats were similarly treated. It was found that the younger rats were far more susceptible to lathyrogenic influences than the older rats. For example, the rate of aortic physiosclerosis was significantly retarded in the six-week-old rats at dosages of 0.00125M and 0.0025M (the six-week-old rats exposed to 0.005M AAN were eliminated from the experiment before its completion), whilst physiosclerosis was unaffected even in those 12-week-old rats exposed to 0.005M AAN. The degree of mineralization of the femur (as reflected by its ash, Ca, Mg, Na, and K content) was retarded in approximately dose-dependent fashion in the rats of both ages, the effect being somewhat more pronounced in the younger animals. These results were discussed in the context of the known effects of lathyrogenic compounds on the biochemical maturation of connective tissue components, and also in the context of previous attempts to modify the lifespan of laboratory animals by lathyrogen administration.

Increased alpha1-fetoprotein production in rat liver injuries induced by various hepatotoxins

Serum alpha1-fetoprotein (AFP) concentration in 5-week-old rats was measured by the radioimmunoassay technique after a single administration of various hepatotoxins. Marked elevation of serum AFP concentrations occurred in rats treated with carbon tetrachloride, thioacetamide, D-galactosamine, allyl alcohol, allyl formate, and ethionine in 4 days of these treatments. The increased production of AFP appeared to be correlated with the induction of liver glucose-6-phosphate dehydrogenase (G-6-PD) among biochemical parameters studied for hepatocellular injuries. However, the difference in time courses of the increase in liver G-6-PD activity and serum AFP level following CC14 treatment suggested that the increased production of serum AFP and the induction of G-6-PD in injured liver were caused by closely related but different mechanisms. Pretreatment of CC14-injured rats with N,N'-diphenyl-p-phenylenediamine or aminoacetonitrile was effective not only in lowering the increased level of serum AFP and liver G-6-PD but also in preventing liver cell necrosis and steatosis induced by CC14. Treatment with a lower dose of thioacetamide resulted in littel elevation of serum AFP and liver G-6-PD with a markedly increased incorporation of 3H-thymidine into liver DNA without any evidence of liver injury. On the other hand, the administration of ethionine, which caused little necrosis of liver cells, produced increase in both serum AFP and liver G-6-PD levels with an only small increase of hepatic DNA synthesis compared to those following thioacetamide as well as CC14. These results suggest that the elevation of serum AFP is not directly related to the stimulation of hepatic DNA synthesis. Some additional mechanisms of specific gene amplification for AFP, which is geared to hepatic injury per se, appear to play a major role in the increased AFP production in injured liver.

[Comparative pharmacological effects of dl-amphetaminil and dl-amphetamine in the rat]

The present investigation shows that amphetamine and amphetaminil produce identical pharmacological effects (increase in motility and body temperature, anorexia, stereotypic behaviour). There was neither a qualitative difference under "open field" conditions nor a difference in the capacity of modifying the reserpine induced syndrome. In isomolar doses amphetamine was somewhat more effective. Almost the same amounts of amphetamine were found in blood and brain following amphetamine or amphetaminil administration, with exception of somewhat higher peak levels after amphetamine. These results favor the hypothesis that amphetaminil effects are produced by the amphetamine molecule.

Collagen and mechanical strength in various organs of rats treated with D-penicillamine or amino-acetonitrile

After oral treatment with D-penicillamine (D-Pc) or with aminoacetonitrile (AAn) for 10 days, mechanical and chemical parameters were studied simultaneously in various organs of Sprague Dawley rats. Tensile strength of skin strips and of tail tendons, breaking strength of femur bones and tensile strength of granuloma tissue (induced by implanted glass rods) were measured and calculated. In the same tissue the soluble collagen fractions and the insoluble collagen were determined. Total collagen and the ratio insoluble vs. soluble collagen were calculated. Tensile strength of skin, tendon and granuloma tissue were greatly reduced by D-Pc treatment but only minimally influenced by AAN treatment. On the other hand only AAN significantly reduced the breaking strength of bone. All these changes were closely correlated with the content of insoluble collagen in the respective tissues. The correlation coefficients to total collagen were similar but lower. The correlation coefficients between strength and the ratio insoluble vs. soluble collagen were generally still lower. Earlier findings in aged and corticoid treated rats, proving that insoluble collagen content determines mechanical strength of connnective and supporting tissue thus could be confirmed.