The influence of aminoguanidine on borohydride reducible collagen cross-links and wound strength.

The mechanical strength of skin wounds as well as the deposition of hydroxyproline and KB3H4 reducible hydroxylysinonorleucine (HLNL) and dihydroxylysinonorleucine (DHLNL) cross-links in subcutaneously implanted cellulose sponges have been investigated in rats treated with aminoguanidine (AG) or beta-aminopropionitrile (BAPN). Treatment with AG (25 mg/kg BW/day) did not influence the mechanical strength of the wounds, the deposition of hydroxyproline or the pattern of reducible collagen cross-links, whereas AG (125 mg/kg BW/day) reduced the maximum load by 17%, but did not influence the deposition of hydroxyproline or reducible cross-linking pattern. Treatment with BAPN (333 mg/kg BW/day) reduced the strength of the wounds by 59%, the HLNL by 50% and the DHLNL 57%, whereas the deposition of hydroxyproline did not seem to be influenced by BAPN treatment. In conclusion, AG at moderate dosage does not seem to influence the formation of lysyl oxidase dependent reducible cross-links of collagen.     

BAPN dose dependence of mature crosslinking in bone matrix collagen of rabbit compact bone: corresponding variation of sonic velocity and equatorial diffraction spacing

Crosslinking density in demineralized bone matrix collagen was found to depend on the beta-aminopropionitrile (BAPN) dose level for compact bone from rabbit femurs. The dependence was demonstrated for the hydroxypyridinium (HP) concentration, a mature crosslink. A more consistent dependence on BAPN dosage was observed for the fraction of the demineralized bone matrix insoluble in 0.5 M acetic acid (AIF) corresponding to the remaining crosslinked collagen. The average HP concentration in 21 week old controls was 0.24 moles HP/mole collagen which decreased to 0.13 +/- 0.04 for the same age rabbits dosed with 1 gm BAPN/kg/day for 13 wks. The comparable mean AIF values were 0.91 for controls and 0.75 for maximum dose level. Most of the effect of BAPN on crosslinking was observed at the lower dosages below 0.2 g/kg/day. On the other hand, overt osteolathyritic symptoms are seen only for BAPN dosages greater than 0.2 g/kg/day. The mean sonic plesio-velocity was previously found to decrease from 3.4 to 3.03 km/sec as the BAPN dosage was increased. A similar close relationship was discovered for the equatorial diffraction spacing in fully mineralized bone which increased from 1.235 for normal rabbit bone to 1.28 nm for maximum dose. Most of the effect on these physical properties is exhibited at the highest BAPN dosage after much of the decrease in mature crosslinking density has been observed and when the further decrease in mature crosslinking density proceeds very slowly with increased drug dosage. These observations suggest that osteolathyrism does not become manifest until practically all mature crosslinking that can be affected has been inhibited. The mineralization process apparently can be maintained in the newly laid collagen even in the presence of severe osteolathyritic conditions. Intermolecular crosslinking in bone collagen appears to play an important role in the development of bone properties whether by direct or indirect processes. Much of the effects on bone properties occur at the higher BAPN dosages where overt osteolathyrism is observed and where there seem to be only small changes in crosslinking density.     

Effect of cis-hydroxyproline on collagen and other proteins in skin wounds, granuloma tissue, and liver of mice and rats

Acute and chronic pharmacologic effects of cis-hydroxyproline (cis-Hyp) were studied in mice and rats. Given as a single dose intraperitoneally, cis-Hyp is relatively non-toxic and the LD₅₀ approaches that of l-proline.Chronic administration of cis-Hyp (200 mg/kg/day) to mice did not affect breaking strength of dermal wounds or content and specific activity of noncollagenous protein in the liver. Although cis-Hyp produced a significant decrease tn noncollagenous protein content of polyvinyl alcohol sponge induced granuloma tissue, collagen content and rate of synthesis in granuloma tissue and liver were increased significantly.Rats given cis-Hyp (200 mg/kg/day subcutaneously in divided doses every 12 hr) and control animals demonstrated identical hepatic microsomal protein, cytochrome P₄₅₀ and cytochrome b₅ content. Breaking strength of dermal wounds was increased significantly in treated animals. Ultrastructural analysis of rat liver failed to demonstrate any structural alterations of cellular organelles due to cis-hyp treatment.We conclude that chronic in vivo administration of cis-Hyp does not inhibit collagen synthesis or accumulation in normal or repaired tissues and does not decrease the breaking strength of skin wounds. Other effects on protein metabolism could result from nonspecific, chronic toxicity of cis-Hyp.     

Histamine and collagen levels in the lathyritic chick embryos after administration of 48/80

The studies were undertaken to investigate the influence of compound 48/80 on histamine (Hi) and collagen levels of chick embryos after administration of lathyrogen factor, -aminopropionitrile (BAPN). Hi and soluble collagen levels in bones (tibia and femur) and skin were significantly higher in the embryos treated with BAPN. Compound 48/80 administered together with BAPN lowered Hi and soluble collagen in the bones and skin as compared with the embryos treated with BAPN alone. Both, in the skin and bones, 48/80 was found to be a protective factor against the changes in biosynthesis of collagen.     

Effect of beta-amino-propionitrile on the regenerating newt limb evaluated by uptake of 3H-proline and 3H-lysine

Newt forelimbs were unilaterally amputated and Beta-amino propionitrile (BAPN) was added to the water in which the newts were maintained. Sixty-three days after amputation, animals were injected with either 3H-proline or 3H-lysine. Forelimbs distal to the elbow of both amputated and non-amputated sides were removed 72 hours later. Uptake of 3H-proline and 3H-lysine in whole limbs was assessed by liquid scintillation and in cartilage cells and matrix by autoradiography. Amputation was a potent stimulus to both collagen formation and maturation during regeneration. BAPN reduced the stimulatory effect of amputation on collagen formation but not on its maturation. Collagen synthesis and maturation are independent events and, in intact non-regenerating limbs, BAPN adversely affected collagen maturation while collagen synthesis was unaltered.     

Influence of Arecoline on Immune System: I. Short Term Effects on General Parameters and on the Adrenal and Lymphoid Organs

Abstract

Arecoline, a suspected carcinogenic/cocarcinogenic alkaloid was screened to explore in detail its immunomodulatory influence in murine model system. The oral LD₅₀ value for male mice was 371 mg/kg bw whereas it was 309 mg/kg bw for female mice. The subcutaneous LD₅₀ value for both sexes was 97 mg/kg bw. Only a marginal difference was observed in intraperitoneal LD₅₀ values between male (120 mg/kg bw) and female (109 mg/kg bw) mice. Arecoline was administered subcutaneously to male mice at subtoxic dose levels (5, 10, and 20 mg/kg bw) for 1, 2 and 3 weeks on a daily basis. In groups where significant decreases in body weight were present (at 20 mg/kg bw for both sexes), reductions in thymus weight were also noted. Spleen, mesenteric lymph nodes (MLN), liver, and kidney showed moderate reductions in their weights. Histopathological effects at 20 mg/kg bw included lymphocyte depletion of the thymic cortex, and the B and T lymphocyte areas in spleen and MLN. In concordance with the zona fasciculate hypertrophy of adrenals, corticosterone concentration in serum increased depending on the dose with a significant elevation at 20 mg/kg bw. While total protein, albumin, glucose, acid phosphatase and hemoglobin concentrations were not altered, increases in SG0T and SGPT levels were observed at the high dose. The white and red blood cell counts decreased in a dose-dependent manner. Marked reduction in cell number of thymus, and moderate effect on cellularity of spleen and MLN, were observed at 20 mg/kg bw. In vitro exposure of rat thymocytes to arecoline resulted in a biphasic oxygen consumption response with progressive increase in oxygen consumption, reaching a maximum value at 10^?5 M and decreasing sharply at 10^?3 M, Exogenously added substrates such as glucose, pyruvic acid and lactic acid retarded the fall in the oxygen consumption induced at 10^?3 M arecoline. These observations demonstrate the effects of arecoline on lymphoid organs, which may be due to its direct action or through the elevation of corticosterone.     

Chronic lathyrism. Protective effect of pyridinol carbamate on connective tissue lesions in the rat (author's transl)]

The use of lathyric toxins (BAPN) in low dosage (1 g/kg/day) for a period of 8 weeks caused in the rat simultaneous changes in the skin and aortic connective tissues. In the skin. collagen tissue was dislocated and broken in fragments, the elastic tissue disappeared, the fibroblasts were vacuolized and presented evidence of injury. These lesions were comparable to those observed in human skin during ageing. The addition of pyridinol carbamate (PDC) to BAPN prevents the formation of lesions of the elastic tissue and of fibroblasts. When given after the cessation of the lathyrogen treatment PDC arrested the formation of the lesions and accelerated their regression.     

Enhanced Toxicity for Mice of Combinations of Antibiotics with Escherichia coli Cells or Salmonella typhosa Endotoxin

Enhanced lethality for BALB/c mice has been observed after the administration of Salmonella typhosa endotoxin with either actinomycin D, cycloheximide, or nogalamycin. The dose of actinomycin D required to kill half of the mice (LD₅₀) was 0.8 mg/kg in normal animals, 0.35 mg/kg in mice administered 0.08 mg of endotoxin per kg, and 0.28 mg/kg in mice administered 0.2 mg of endotoxin per kg. The LD₅₀ of endotoxin in normal mice was 12 mg/kg and in mice given 0.4 mg of actinomycin D per kg was 0.067 mg/kg. The LD₅₀ of actinomycin D in mice administered 1.8 × 10⁸ live Escherichia coli cells per kg or 1.8 × 10⁹ heat-killed E. coli cells per kg was reduced to 0.4 mg/kg. The LD₅₀ of cycloheximide was 181 mg/kg in normal animals and 28 mg/kg in mice administered 4 mg of endotoxin per kg. The LD₅₀ of endotoxin in mice given 120 mg of cycloheximide per kg was 0.02 mg/kg. Enhanced lethality due to various combinations of cycloheximide and endotoxin was abolished by pretreatment of mice with endotoxin. The LD₅₀ of nogalamycin was 21 mg/kg in normal mice and 13 mg/kg in mice receiving 1 mg of endotoxin per kg.     

Effects of Hydrocortisone and β-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 &#103 -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.     

No release of histamine and substance P in capsaicin-induced neurogenic inflammation in intact human skin in vivo: a microdialysis study

Background Studies in rodents ‘skin have indicated substance P to be the main inflammatory mediator involved in neurogenic inflammation, acting partly by release of histamine from skin mast cells. The mediators released in neurogenic inflammation in human skin remain to be determined. Objectives To determine the effects of intradermally injected and topically applied capsaicin on the release of histamine and substance P and skin responses in intact human skin in vivo. Methods Extracellular skin levels of histamine and substance P were measured by microdialysis technique and assayed by enzyme and radio immunoassays. Two kinds of dialysis fibres (210μm, 2 kDa, and 500 μm, 20 kDa) were inserted intradermally into forearm skin for studies of histamine release to topically administered capsaicin and intradermally injected capsaicin and substance P. Results Baseline histamine skin levels were 8.0 ± 0.7 nM. Intradermally injected capsaicin (0.3–30μM, 7.5–750 pmol) caused significantly and dose-related flare and pain reactions, but no significant histamine release or weals. Intradermally injected substance P (1 and 3 μM, 25 and 75 pmol) released significant amounts of histamine (peak levels being 90 and 475 nM), evoked weal-and-flare reactions, but did not cause pain. Capsaicin 2% ointment, applied on the skin for 2.5 h, increased skin blood flow by 300–400% as measured by laser Doppler flowmetry, elicited a longstanding burning sensation, but did not release histamine. Substance P-like immunoreactivity (SP-LI) was below the 1.8 pM detection limit following insertion of 20 kDa dialysis fibre and after intradermal injection of capsaicin 3μM. Intradermal injection of injection of 1 μM of substance P increased SP-LI levels to values greater than 4500 pM, confirming the ability of the dialysis fibre to recover this peptide. Conclusions Capsaicin-induced neurogenic activation does not involve the release of histamine from mast cells or detectable amounts of substance P release from sensory nerves in normal human skin in vivo.     

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.     

The concentration-dependent effect of anethole on collagen,MMP-2 and GAG in human skin fibroblast cultures

PurposeIn aging skin and some skin disorders, components of skin extracellular matrix (ECM) are disturbed and therefore research to find skin drugs is important. Evaluation of anethole impact on collagen, GAGs and MMP-2 in human skin fibroblasts was the aim of this study.Materials and methodsFor collagen assay the Sircol dye, 5-[³H]proline and real time-PCR were used. MMP-2 activity was detected by zymography. GAG concentration was determined using 1,9-dimethylmethylene blue (DMMB). Cell viability was assayed with MTT.ResultsIn cells treated with 1 and 10 μM anethole, a significant increase in collagen synthesis was demonstrated. In contrast, collagen synthesis was significantly decreased in cells exposed to 100 μM anethole. Similar alterations were found in collagen type I expression. The concentration of collagen secreted into the medium was higher only in cells exposed to 1 μM anethole, while it was lower under the influence of higher compound concentrations. It may be due to the lack of pro-MMP-2 activation at 1 μM and a significant increase in the level of MMP-2 at 10 and 100 μM anethole. GAG concentration was reduced under the influence of 100 μM anethole, whereas anethole at lower concentrations revealed the ability to prevent H₂O₂-induced GAG increase. No significant cytotoxicity of anethole to fibroblasts was noted.ConclusionsOur findings demonstrate the concentration-dependent action of anethole on the crucial components of ECM in cultured skin fibroblasts, which may be somewhat beneficial and may possibly be developed towards a therapeutic use in some skin disorders.     

Growth of a plasma cell myeloma in lathyritic mice.

Growth of a plasma cell myeloma (Adj PC-5) was studied in mice made lathyritic by the administration of beta-amino-proprionitrile (BAPN). The number of bones that had their medually cavities filled with tumor cells was notably decreased compared with tumor-bearing mice not treated with BAPN. Other aspects of tumor growth were the same. BAPN caused some retardation of tumor growth in the medullary cavity, but also caused osteoporosis and decreased tensile strength of collagen that allowed expansion of tumor growth outside the bones to proceed as usual. Additionally, the tumor-bearing mice showed some inhibition in their response to BAPN. This agrees with previous work that has shown that the response to BAPN treatment is greatest in animals that otherwise are healthiest.     

Homocysteine-induced convulsions in the rat: Protection by homoserine,serine, betaine,glycine and glucose

Intraperitoneal injection into rats of 5.5 mM/kg ofdl-homocysteine (free base) ordl-homocysteine thiolactone · HCl resulted in violent convulsions (approx. 50%) and some fatalities (approx. 15%), following a short, initial period of depressant activity. Metabolically related metabolites (viz. methionine, serine, homoserine, cysteine and homocystine) showed no convulsant activity and virtually no lethal effects at doses as high as 7.4 mM/kg. At 7.4 mM/kg, homocysteine and its lactone resulted in 95% convulsions and 90% fatalities. These obervations point to a structural factor for convulsant activity indl-homocysteine not found in the related methionine metabolites tested. The half-maximal convulsant dose (CD₅₀) was 750 (698–806) mg/kg and the half-maximal lethal dose (LD₅₀) was 840 (794–889) mg/kg, both values having Litchfield-Wilcoxon confidence limits of 19/20. Prior intraperitineal injection of large doses (14.8 mM/kg) of homoserine, serine, betaine, glycine and glucose protected against convulsions and death induced by the CD₅₀ dose (i.e. 750 mg/kg) ofdl-homocysteine. Our findings indicate that, of all the major metabolites of methionine tested, homocysteine would seem to be the only one which is epileptogenic and the most toxic (to the point of lethality).     

Efficacy of cecropin A-melittin peptides on a sepsis model of infection by pan-resistant <Emphasis Type="Italic">Acinetobacter baumannii</Emphasis>

Pan-resistant Acinetobacter baumannii have prompted the search for therapeutic alternatives. We evaluate the efficacy of four cecropin A-melittin hybrid peptides (CA-M) in vivo. Toxicity was determined in mouse erythrocytes and in mice (lethal dose parameters were LD₀, LD₅₀, LD₁₀₀). Protective dose 50 (PD₅₀) was determined by inoculating groups of ten mice with the minimal lethal dose of A. baumannii (BMLD) and treating with doses of each CA-M from 0.5 mg/kg to LD₀. The activity of CA-Ms against A. baumannii was assessed in a peritoneal sepsis model. Mice were sacrificed at 0 and 1, 3, 5, and 7-h post-treatment. Spleen and peritoneal fluid bacterial concentrations were measured. CA(1–8)M(1–18) was the less haemolytic on mouse erythrocytes. LD₀ (mg/kg) was 32 for CA(1–8)M(1–18), CA(1–7)M(2–9), and Oct-CA(1–7)M(2–9), and 16 for CA(1–7)M(5–9). PD₅₀ was not achieved with non-toxic doses (≤LD₀). In the sepsis model, all CA-Ms were bacteriostatic in spleen, and decreased bacterial concentration (p < 0.05) in peritoneal fluid, at 1-h post-treatment; at later times, bacterial regrowth was observed in peritoneal fluid. CA-Ms showed local short-term efficacy in the peritoneal sepsis model caused by pan-resistant Acinetobacter baumannii.     

α1-Adrenoceptors antagonize activated chloride conductance of amphibian skin epithelium

 The effects of adrenoceptor agonists on the transepithelial Cl^– conductance (G ^Cl) in the skin of several amphibian species, both toads and frogs, were studied. Epinephrine (Epi) from the serosal side selectively and reversibly inhibited the voltage-activated G ^Cl in toad skin and the short-circuit G ^Cl in frog skin. The main effects of activation of the adrenoceptors must reside in the skin epithelium and not in the glands, since measurements were made both from intact skins and split epithelia with essentially the same results. Effective concentrations of Epi were variable among individual tissues. G ^Cl was reduced to 34±17% (n=46) with 1 μmol/l Epi, but in some tissues 0.1 μmol/l inhibited more than 80% of G ^Cl, whereas some preparations were little influenced at >3 μmol/l Epi. The affected receptor type was identified by the use of the α₁-agonist phenylephrine, which mimicked the response of Epi at concentrations above 30 μmol/l, whereas the α₂-agonists xylazine and iodoclonidine had no effect at supramaximal concentrations. Prazosin, a specific α₁-antagonist, reduced or eliminated the inhibition by Epi, but the response pattern suggests a low affinity. The α₂-antagonist yohimbine, at concentrations ≤0.3 μmol/l, had a minimal effect, but reduced the inhibition by Epi at concentrations of 1–10 μmol/l. This might indicate affinity to α₁-adrenoceptors in amphibian skin. Activation of β-adrenoceptors by isoproterenol (0.1–5 μmol/l) led to a transient increase of the baseline inactivated component of G ^Cl with a slight reduction of the voltage-activated G ^Cl at the higher concentrations, but the inhibitory effect of Epi was not altered. Epi, on the other hand, neither prevented nor reversed the induction of a voltage-insensitive G ^Cl in toad skin caused by application of cAMP at supramaximal concentrations (>100 μmol/l CPT-cAMP). Preincubation of the serosal medium with Ca²⁺-free solution (in the presence of 2 mmol/l EGTA) for extended periods of time (>30 min) eliminated the response to Epi. It is concluded that α₁-adrenoceptors participate in the physiological control of voltage-activated Cl^– conductance in amphibian skin epithelium via modulation of intracellular Ca²⁺, presumably by efflux from intracellular stores. Received: 11 March 1998 / Received after revision: 2 June 1998 / Accepted: 8 June 1998     

Action of diethixime,a new cholinesterase reactivator,on the central nervous system

A new cholinesterase reactivator, p-bromobenzoylthiohydroximic acid S-diethylaminoethyl ester hydrochloride (diethixime, containing a tertiary nitrogen atom in its molecule), in a dose of 20 mg/kg (0.02 LD₅₀), unlike dipyroxime (containing a quaternary nitrogen atom), in a dose of 3 mg/kg (0.02 LD₅₀), was shown to have a central action on rats and rabbits poisoned with dimethyldichlorovinyl phosphate. This was shown by restoration of acetylcholinesterase activity in various parts of the rabbits' brains and normalization of the electroencephalogram and of the functional state of the spinal motoneurons of the rats.Laboratory of General Toxicology and Laboratory of Experimental Therapy, All-Union Scientific-Research Institute of Hygiene and Toxicology of Pesticides, Polymers, and Plastics, Kiev. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Zakusov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 1, pp. 29–32, January, 1977.     

Force deficits after stretches of activated rat muscle-tendon complex with reduced collagen cross-linking

The forces produced during stretches of passive and activated muscles, and isometric force deficits after stretching of activated muscles were examined in rat plantor flexor muscle-tendon complexes with reduced collagen cross-links (pyridinoline). Female Sprague-Dawley rats (n=6, age 87 days) were injected twice daily for 43 days with β-aminopropionitrile (BAPN, 333 mg/kg/day i.p.), an inhibitor of lysyl oxidase, which is responsible for the production of collagen cross-links. The relative weights of the plantar flexor muscles were similar for BAPN and saline-injected (control, C) rats (n=6). Pyridinoline was lower in the tendon (22.9%), and in the plantaris (17.1%), and soleus (7.4%) muscles (P<0.05), with no changes observed in collagen content (hydroxyproline), as determined by high-pressure liquid chromatography. At an ankle position of 90°, groups had similar forces at 5, 10, 20, 40, 60 and 80 Hz before stretching. Forces at 40° with stretches of the passive muscles (five times from 90° to 40°) were lower for all stretches in BAPN-injected rats (P<0.05). Isometric force deficits resulting from stretches of activated muscles (80 Hz, 20 times from 90° to 40°, rest intervals 3 min) followed similar courses for BAPN-injected and C rats, and were 51.1 (2.4)% (C) and 54.7 (4.6)% (BAPN) before the last stretch. After 1 h of rest, isometric force deficits were 26% and 29% larger at 10 Hz and 5 Hz, respectively, in BAPN-treated rats (P<0.05). The reduction in BAPN-injected collagen cross-linking of the skeletal muscle-tendon complex reduced the forces produced during stretches without muscle stimulation (i.e. passive stretch), and stretching of activated muscles produced larger isometric force deficits only at low stimulation frequencies. Electronic Publication     

Phenytoin inhibition: failure to inhibit periosteal responses to lathyrogen

beta-Aminopropionitrile (BAPN) administered to rats has caused exostosis formation at sites of muscle attachment and also caused delay in the healing of soft tissue wounds and of bone fractures. Since phenytoin sodium has an opposite effect on wound healing, bone fractures, and the tensile strength of connective tissues, an experiment was performed to determine whether or not BAPN could produce periosteal exostoses in the presence of phenytoin. Rats that were given both BAPN and phenytoin produced similar exostoses as rats that were given BAPN alone. This indicates that phenytoin does not prevent inhibition of lysyl oxidase by BAPN, does not promote increased tensile strength of connective tissues in the presence of BAPN, and does not facilitate the detoxification of BAPN. Further, no evidence for an increased cellular response with phenytoin was observed. The mechanism by which phenytoin promotes wound healing is still unknown.