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Mortality, hemodynamics, and aortic properties among male and female turkeys fed beta-aminopropionitrile.

Broad-Breasted White turkeys were randomized into four treatment groups at 4 weeks of age in each of three trials. Group 1, males, and Group 2, females, were fed an unsupplemented (control) diet from 4 to 10 weeks of age. Group 3, males, and Group 4, females, were fed the control diet supplemented with 0.07% beta-aminopropionitrile (BAPN). The experiments were terminated at 10 weeks of age. There was no mortality among male and female turkeys fed the control diet or significant differences in blood pressure, heart rate, aortic tensile strength, or aortic hydroxyproline between these males and females. Sixty-five percent of the males and 21% of the females fed BAPN died of dissecting aneurysms; blood pressure, heart rate, and dp/dt max were not altered as a result of feeding BAPN. Aortic tensile strength was higher in control turkeys than those fed BAPN, but males fed BAPN had the lowest value. Males fed BAPN also had the lowest aortic hydroxyproline content. Ultrastructural alterations of aortic elastic and collagen fibers were more severe in males than females fed BAPN. Aortic changes did not occur in control turkeys.

Aminopropionitrile↗

Cartilaginous metaplasia of the thoracic aorta of control turkeys and exacerbation by beta-aminopropionitrile.

Seventeen of sixty distal extremities of the thoracic aortas of 12-week-old control male turkeys and 37 of 40 distal extremities of the aortas of turkeys fed 0.07% beta-aminopropionitrile (BAPN) from 4 to 12 weeks of age contained areas of cartilaginous metaplasia when examined by light microscopy. The cartilaginous areas were generally elongated and located in the subendothelium of control turkeys, but a roundish area of cartilage was occasionally evident in the deep media. The magnitude of chondroplasia was enhanced by feeding BAPN; the extensive lesion usually extended from the subendothelium to deep in the media. Regardless of treatment, chondrocytes were pleomorphic, contained vacuoles, and had cytoplasmic processes. The cells were separated by pools of proteoglycans and connective tissue. The ultrastructure of chondrocytes in the aortas of both treatment groups was typical of this cell type. They had undulations or projections of the cell membranes. The cisternae of endoplasmic reticulum were dilated and contained electron-translucent material which was similar to extracellular proteoglycans. Golgi apparatus, free ribosomes, mitochondria, glycogen granules, filaments, and a centriole also were present in the cytoplasm. The extracellular matrix, which included collagenous and elastic fibers and also delicate fibrils and interconnecting matrix granules, separated adjacent chondrocytes by spaces of varying size.

Aminopropionitrile↗

Effect of beta-aminopropionitrile and ascorbate on fibroblast migration.

Ascorbate and beta-aminopropionitrile (BAPN) have direct, but diverse affects on collagen matrix production. Ascorbate is necessary for the intracellular hydroxylation of prolyl and lysyl residues during collagen biosynthesis whereas BAPN inhibits the enzyme lysyl oxidase in the extracellular space thus preventing collagen crosslink formation. To study the influence of these two agents on fibroplasia, an in vitro model was used to analyze fibroblast migration, proliferation, and collagen synthesis. Biopsies of chicken tendon were covered with a fibrin clot to simulate an in vivo wound environment, and then they were exposed to either ascorbate or BAPN for up to 7 days. Fibroblast migration into the fibrin clot was measured using a Zeiss Mopp II planimeter, DNA synthesis by 125IUDR incorporation, and collagen synthesis by [3H]proline incorporation into collagenase-digestible protein. Tendon biopsies treated daily with fresh ascorbate (0.1 mM) had significantly greater fibroblast migration than controls without ascorbate (P less than 0.05). Cellular proliferation, collagen synthesis, and total protein synthesis were not significantly altered by ascorbate treatment. In contrast, BAPN inhibited fibroblast migration in a dose-dependent fashion without inhibiting proliferation (0.25 and 0.5 mM), collagen, and noncollagen protein synthesis. Therefore, the effect of BAPN on migration does not appear to be due to generalized cytotoxicity. These combined studies suggest that compounds such as ascorbate and BAPN which can modify collagen may also modify fibroblast migration.

Aminopropionitrile↗

Effect of beta-aminopropionitrile on in vitro bone lipid synthesis.

The effect of beta-aminopropionitrile (BAPN) on lipid synthesis and 14CO2 production from 14C-acetate by rat calvariae in vitro was investigated by biochemical, histochemical, and autoradiographic techniques. Exposure of bones to 5 mM BAPN throughout a 5-hour incubation period resulted in little effect on lipid synthesis when compared with control bones. Higher BAPN concentrations, up to 100 mM, during this short incubation period resulted in enhanced lipid radioactivity for most of the identified lipid classes. Longer preincubation periods of 20 hours and low BAPN (20 mM) concentrations resulted in enhanced lipogenesis. As BAPN concentrations above 20 mM were employed, lipogenesis decreased to such a level that some lipid classes failed to become labeled with 14C-acetate. 14CO2 production from 14C-acetate by a rat calvariae was affected by BAPN concentration and incubation time in a pattern similar to that of lipid synthesis. Histochemistry demonstrated neutral fat in the osteogenic cells and phospholipids in osteoblasts and the osteoid matrix. Autoradiographic localization of 14C-acetate revealed that the radioactivity was in the osteogenic cells and that this activity was markedly increased after pretreatment of the calvariae with BAPN. This study shows that some concentrations of BAPN enhance lipogenesis by rat calvariae and supports the earlier suggestion that lipids play a role in biologic calcification.

Acetates↗

An angiotensin-converting enzyme inhibitor, not an angiotensin II type-1 receptor blocker, prevents beta-aminopropionitrile monofumarate-induced aortic dissection in rats.

OBJECTIVE: Cystic medial degeneration (CMD) is a histologic abnormality that is common in aortic diseases such as aortic dilation, aneurysm, or dissection. Although little is known about the mechanism underlying CMD, we have previously demonstrated that angiotensin II signaling via angiotensin II type 2 receptor (AT2R) plays a central role in apoptosis of vascular smooth muscle cells (VSMCs) occurring in CMD associated with Marfan syndrome. The aim of this study is to elucidate the role of angiotensin II signaling in THE pathogenesis of aortic diseases associated with CMD. METHOD: We investigated the effects of angiotensin-converting enzyme inhibitor (ACEI), temocapril (n = 15), angiotensin II receptor type-1 (AT1R) blocker, CS-866 (n = 15), and vehicle control (n = 17) on 0.25% beta-aminopropionitrile monofumarate (BAPN)-induced aortic dissection and histopathologic findings in a rat model. RESULTS: Temocapril significantly prevented aortic dissection (P <.05), CMD (P <.01), and VSMC apoptosis (P <.01) compared with vehicle control in BAPN-fed rats. However, CS-866 did not show any preventive effect. Reversed transcriptase-polymerase chain reaction demonstrated that expression of both AT1R and AT2R was detected in control rat aortas, and that AT2R expression was significantly upregulated in the aortas of BAPN-fed rats (P <.01). Blood pressure was significantly and equally lowered in both temocapril and CS-866 groups compared with control. CONCLUSIONS: Differential expression of angiotensin II receptors and AT2R signaling are involved in the pathogenesis of CMD and aortic dissection in BAPN-fed rats. ACEIs might be of clinical value for the prevention and treatment of aortic diseases related to CMD.

Aminopropionitrile↗

Effects of hydrocortisone and beta-aminopropionitrile on stress-strain and stress-relaxation behaviors, and birefringent retardation of collagen fibers in the rat incisor periodontal ligament.

Three groups of male Wistar rats received daily subcutaneous injections of 10 mg/kg of hydrocortisone (HC group), 300 mg/kg of beta-aminopropionitrile (BAPN group), or saline (control group), for 10 days. The shear stress-strain and stress-relaxation properties of the incisor periodontal ligament were examined in transverse sections from dissected mandibles. Both the maximum shear stress and failure strain energy density increased significantly following the administration of hydrocortisone. The maximum shear stress decreased following the administration of BAPN. However, the stress-relaxations in the initial 10 min did not show significant differences among the three groups. Polarized light microscopic analysis revealed that the retardation value of the collagen fibers was highest in the HC group and lowest in the BAPN group for the bone-related area, but not for the tooth-related and middle areas of the ligament. It is suggested that the changes induced by hydrocortisone or BAPN occurred mainly in the elastic components and to a minor extent in the viscous components although the physical and biomechanical properties are determined by the interaction of all the various components. We also suggest that the main response to the drugs occurred in the collagen fibers in the bone-related area of the ligament.

Aminopropionitrile↗

Electron microscopic observations of elastic fibres in the lung and aorta of tight-skin and beta-aminopropionitrile-fed mice.

The lung of the tight-skin (TSK) mouse was characterized by enlargement of the air spaces. Elastin in the alveolar walls of the TSK mouse exhibited fragmentation. The aorta of the TSK mouse was characterized by marked hyperplasia of loose connective tissue in the adventitia. Collagen fibres and ruthenium red-positive materials were markedly increased. Microfibrils surrounding elastin in the adventitia of the aorta were not clear in the TSK mouse. In the lung of the beta-aminopropionitrile (BAPN)-fed mouse, enlargement of the alveolar air spaces was not prominent compared with the TSK mouse. Elastic fibres in the alveolar walls did not show the fragmentation observed in the TSK mouse, and microfibrils surrounding elastin were clearly observed. However, elastic laminae in the media of the BAPN-fed mouse aorta were swollen and fragmented. Elastic fibres in the adventitia exhibited a normal appearance and microfibrils surrounding elastin in the adventitia were clearly observed. The results suggest that the mechanism of the connective tissue abnormality in the TSK mouse is different from that of BAPN, which inhibits the activity of lysyl oxidase. The abnormality of elastin and microfibrils surrounding elastin in the TSK mouse probably plays a role in the deformity or degradation of elastic fibres and the structural changes of the lung.

Aminopropionitrile↗

Influence of beta-aminopropionitril on media hypertrophy and baroreceptor reflex in normotensive and hypertensive rats.

Experiments were performed to investigate the antihypertensive action of beta-aminopropionitril (BAPN) in normotensive and hypertensive rats and to elucidate the role of media hypertrophy and arterial wall distensibility on baroreceptor reflex and blood pressure (BP) regulation. Normotensive Wistar-Kyoto rats (WKY), DOCA-salt hypertensive WKY, and stroke-prone spontaneously hypertensive rats (SHRSP) were treated with BAPN (100 mg/kg per day, intraperitoneally) for 10 weeks. The respective control groups (n = 10 per group) received 0.9% NaC1 instead of BAPN. In BAPN-treated groups the BP of DOCA-salt WKY (145 versus 170 mmHg) and SHRSP (170 versus 208 mmHg) was lower than that of controls at the end of the treatment period. In BAPN-treated rats, the medial cross-sectional area was reduced, postmortem distensibility of vascular wall was greater, and baroreceptor reflex, estimated from heart rate responses to BP changes, showed steeper regression curves. The BAPN-induced BP decrease in the hypertensive rats demonstrates that the level of sensitivity of the baroreceptor reflex is related to the mechanical properties of the arterial wall.

Aminopropionitrile↗

Effects of beta-aminopropionitrile after glaucoma filtration surgery: pilot human trial.

Beta-aminopropionitrile fumarate, an inhibitor of collagen cross-linking, was used topically in patients after filtration surgery for difficult cases of glaucoma (aphakic, repeat surgery, neovascular). Twenty-three patients received the drug for a total treatment period of three months following surgery. The mean preoperative intraocular pressure was 40.0 +/- 14.1 mm Hg (mean +/- standard deviation). The mean postoperative pressure was 19.0 +/- 8.9 mm Hg, with the mean follow-up at 26.4 +/- 11 weeks. The overall success rate was 74%, with success being defined as an intraocular pressure of 22 mm Hg or less at the last visit. Side effects consisted primarily of stinging immediately after the medication was applied. Inhibition of collagen cross-linking may represent an alternative method to the use of injectable 5-fluorouracil to maintain patency of filtration blebs.

Administration, Topical↗

D-penicillamine and beta-aminopropionitrile effects on experimental filtering surgery.

We studied the effect of two compounds, beta-aminopropionitrile (BAPN) and D-penicillamine on the success of experimental glaucoma filtering surgery in cynomolgus monkeys. All animals had laser-induced glaucoma and underwent punch sclerectomy operations. Eyes treated with BAPN or D-penicillamine maintained successful filtration for at least 3 days longer than nondrug-treated controls. This effect, while statistically significant (P less than 0.05), was temporary. The lack of more substantial improvement in prolonging filtering patency may have resulted from an inadequate effective drug concentration. Alternatively, these drugs may have limited potency because their action on new collagen synthesis affects only a minor component of the healing process that causes filter failure.

Aminopropionitrile↗

Potentiating effect of beta-aminopropionitrile on the DNA synthesis induced by isoproterenol.

Young mice chronically treated with beta-aminopropionitrile (BAPN) were subsequently given injections of graded doses of isoproterenol, and the response of various tissues to IPR in synthesizing DNA was analyzed. The results indicate that chronic administration of BAPN potentiates the effect of IPR for inducing DNA synthesis in the parotid, submandibular gland, kidney, and urinary bladder. The effect of BAPN was most pronounced in the submandibular gland. Namely, acinar cells in the submandibular gland normally respond less to IPR than do those in the parotid but respond more when mice have been treated with BAPN. It was suggested that the structural modification of collagen may counteract the blockage of events leading to DNA synthesis in epithelial cells in vivo.

Aminopropionitrile↗

The basement membrane of bovine corneal endothelial cells in culture with beta-aminopropionitrile: biosynthesis of hexagonal lattices composed of a 160 nm dumbbell-shaped structure.

Bovine corneal endothelial cells maintained in culture produced an extracellular matrix on their basal surface. In the presence of beta-aminopropionitrile (beta-APN) (100-500 micrograms/ml), an inhibitor of cross-linking, this extracellular matrix contained hexagonal lattices of 150 nm periodicity. The lattice was composed of round densities 60 nm in diameter comprising the nodes of the lattice and rod-like structures 40 nm in thickness comprising its sides. This structure is almost identical to that of bovine Descemet's membrane in situ. The lattice was produced only in the presence of beta-APN. By freeze-etch replica and negative staining of 1 day cultures, the unit component of the lattice appeared to be a novel 160 nm long dumbbell-shaped symmetrical structure. The central rod of the dumbbell-shaped structure was 80 nm long and 20 to 50 nm in diameter with round ends (40-50 nm). In the rod 2 nm fibrillar substructures were discerned by negative staining. The rod-like central portion was resistant to trypsin digestion whereas the round ends were digested by it. Both structures disappeared after bacterial collagenase digestion. By immunoblotting the extracellular matrix contained 160kd and 180kd bands which bound anti-type IV collagen antibodies and a 140kd band which bound anti-type III collagen antibodies. The lattice area was also positively stained with these antibodies by immunoperoxidase. The findings strongly suggest that the hexagonal lattice of bovine Descemet's membranes in situ is composed of this collagenous structure.

Aminopropionitrile↗

Reaction of aortic lysyl oxidase with beta-aminopropionitrile.

beta-Aminopropionitrile (BAPN) is a potent irreversible inhibitor of lysyl oxidase, the enzyme which initiates cross-linkage formation in elastin and collagen. The initial interaction of BAPN with aortic lysyl oxidase is competitive with elastin or alkyl amine substrates. Irreversible inhibition develops in a time- and temperature-dependent fashion upon incubation of enzyme with BAPN in the absence of substrate with a limiting inactivation rate constant of 0.16 min-1 and a KI of 6 microM at 37 degrees C. The labeled carbons of [1,2-14C]BAPN and [3-14C]BAPN covalently bind to the enzyme to equivalent extents and in parallel with the development of inactivation, negating the possibility that the nitrile moiety is eliminated from BAPN by enzymatic action. The copper content of the enzyme is not significantly altered upon interaction with BAPN. The extent of labeling by [14C]BAPN is reduced by prior treatment of the enzyme with carbonyl-modifying reagents, suggesting the possibility of enzyme-inhibitor Schiff base formation. However, BAPN is not processed to a free aldehyde product upon incubation with lysyl oxidase. A mechanism of inhibition is postulated which involves the formation of a covalent bond between an enzyme nucleophile and a ketenimine formed from BAPN by enzyme-assisted beta-proton abstraction.

Amino Acid Oxidoreductases↗

Effect of beta-aminopropionitrile (BAPN) on corneal wound strength.

BAPN (beta-aminopropionitrile), a known inhibitor of collagen cross-linking, was instilled topically three times a day for 11 to 14 days in the eyes of rabbits after they had sustained central corneal wounds. In eight of nine rabbits, corneal wound tensile strength was significantly less in BAPN-treated eyes as compared to controls. This finding has important implications in all areas of ocular surgery and injury for control of collagen maturation and its complications in healing.

Aminopropionitrile↗

Chronic lathyrism. Plasma, aorta and rat skin treated for five months with beta-aminopropionitrile with or without high fat diet.

Previous experiments proved that white Wistar rats, resistant to spontaneous or experimental atheroma, present arteriosclerosis (parietal aorta lesions) and atheroma lesions (fat deposits) after a 9 week-treatment by Beta-aminopropionitrile (BAPN) followed by a high fat diet. The present work shows that BAPN alone, administered for 5 months, does not induced atheroma; its formation needs both lipid humoral disorders and parietal aortic lesions. It confirms certain facts noted in the aging of man and in the formation of atheroma.

Aminopropionitrile↗

The effects of beta-aminopropionitrile on the growing rat lung.

beta-Aminopropionitrile (beta APN), 500 ng/g body weight was injected intraperitoneally into male rats every 2 days between 2 and 28 days after birth. The lungs were examined structurally and functionally and compared with the lungs of control animals given injections of saline and 28-day-old normal male rats which were not given injections. Lungs volumes, both distended with air at 30 cm H2O and with formalin at 25 cm H2O, were increased in beta APN-treated animals. The architecture of the lung was altered so that there was a large increase in the "core," or air internal to the alveoli of the walls of alveolar ducts and sacs. Animals given injections of beta APN had 40--56% fewer alveoli than those given saline injections and normal animals. Experimental animals had larger alveoli. The lungs or beta APN- treated animals were hypercompliant, and their pressure-volume curves were shifted upward and to the left. There were morphologic changes in collagen and elastic tissue, which were more apparent in the elastic tissue. Since beta APN interferes with the synthesis of elastin and collagen, it appears that alterations in the collagen--elastin network reduces alveolar multiplication in the postnatal period. Control animals given saline had abnormal lungs when compared with normal animals. Their alveoli were larger, and they had fewer alveoli per unit volume. Thus the lung may be sensitive to relatively minor insults in the postnatal period.

Aminopropionitrile↗

The effect of beta-aminopropionitrile on lung development in the rat.

beta-Aminopropionitrile (beta APN) was administered intraperitoneally to rats on postnatal days 1, 3, and 5. Body weight, lung volume, lung weight, number of alveoli per unit area and volume, total number of alveoli in the lung, and the total length of elastic fibers in the lung decreased, and the average alveolar volume increased in comparison with control animals similarly treated with saline. From Day 2 of age to Day 6 the total length of elastic fibers increased in control lungs but remained almost the same following beta APN treatment. Ultrastructurally, both the quality and quantity of elastin in lung alveolar wall were affected. beta APN also inhibited the synthesis of deoxyribonucleic acid in interstitial, endothelial, and Type II epithelial cells of the lung alveolar wall. The diminished number of alveoli gives support to the hypothesis that the elastin-collagen network may play a key role in postnatal alveolar multiplication.

Aminopropionitrile↗

In vitro neuronal changes induced by beta-aminopropionitrile.

beta-Aminopropionitrile (beta APN), a peptide found in leguminous plants, is a multifunctional aminonitrile because it has some action on collagen, elastin, and nervous cells. Due to its action on the nervous system, it is very interesting to show its inhibitory effect on cultures of neurons. In the present study, we have demonstrated that beta APN can produce progressive degeneration of neurons and that this effect is dose-dependant. Neuronal cultures were prepared from 14-day-old rat embryos with a cell density of 10(4) cells/cm2 in the control plates. Progressive concentrations of beta APN (from 10(-7) M to 10(-3) M) were added and a 50 Inhibitory Dose (ID50) of 10(-5) M was found. At concentrations of 10(-5) M of beta APN, the neurons showed a loss of synapsis and thinning of neuronal prolongations. Based on the morphological changes observed, we think that beta APN may be used as a neurodegeneration model similar to that obtained with acrylamide, carbon disulfide, beta-beta'-iminodipropionitrile, or aluminum salts.

Aminopropionitrile↗