The objective of this study was to assess whether concentrations of epidermal growth factor (EGF), fibronectin, and alpha(α)-2-macroglobulin in canine serum remain stable under different storage conditions. Serum was obtained from 10 adult dogs and stored for 7 d at room temperature (RT) and at 4°C and for 1, 3, and 6 mo at -20°C. Bacterial cultures of serum were carried out after 7 d at 4°C and at RT. For each dog and time point, EGF, fibronectin, and α-2-macroglobulin were quantified in duplicate by enzyme-linked immunosorbent assay (ELISA). Mean concentrations of each factor at each time point were used for statistical analysis. No bacterial growth was observed in any samples. Compared to baseline (232.24 ± 49.47 pg/mL), EGF concentration was significantly lower after 1 wk of storage at 4°C (135.39 ± 27.12 pg/mL, P = 0.006), but not at RT (315.85 ± 79 pg/mL, P = 0.6) or after 1, 3, or 6 mo of storage at -20°C (220.84 ± 41.07 pg/mL, P = 0.7; 220.98 ± 78.26 pg/mL, P = 0.8; 266.06 ± 20.39 pg/mL, P = 0.4, respectively). Compared to baseline, concentrations of fibronectin after 1 wk of storage at 4°C or at RT and 1, 3, or 6 mo of storage at -20°C were not statistically different. Compared to baseline (186.67 ± 45.20 mg/dL), the concentration of α-2-macroglobulin after 1 wk of storage at 4°C was significantly increased (244.61 ± 58.27 mg/dL, P = 0.002), but not at RT (177.09 ± 26.99 mg/dL, P = 0.2). The differences in concentration after 3 and 6 mo of storage at -20°C were significant compared to baseline (243.32 ± 42.64 mg/dL, P = 0.005 and 56.39 ± 21.78 mg/dL, P < 0.0001, respectively), but not after 1 mo of storage at -20°C (136.79 ± 25.61 mg/dL, P = 0.1). One week of storage at RT has little effect on the stability of EGF, fibronectin, and α-2-macroglobulin in canine serum. Measured factors remain stable for 3 mo of storage at -20°C.

Two experiments were performed to study the relationship between leukotriene B4 (LTB4) synthesis and placental separation and uterine involution in the cow. In experiment I, the concentration and synthesis of LTB4 by caruncular tissue was lower in cows with retained fetal membranes (RFM cows, n = 11) than in cows that expelled the fetal membranes normally (NFM cows, n = 19). The presence of bacterial cell wall, especially of alpha-hemolytic streptococci and coagulase positive staphylococci enhanced LTB4 synthesis by allantochorion only in NFM cows. In the RFM group, Escherichia coli lipopolysaccharide decreased allantochorionic LTB4 synthesis. With caruncle, only epidermal growth factor increased LTB4 production in NFM cows. In experiment II, the caruncular and endometrial secretion of LTB4 was lower in cows with subuterine involution (SUI cows, n = 5) or cows with SUI and RFM (SUI+RFM cows, n = 4) than in cows with normal uterine involution (NUI cows, n = 8). This decrease was especially noticeable in the previously gravid horn. In the three uterine involution groups, there were no differences in LTB4 synthesis by caruncular tissue taken from the previously gravid horn. However, progesterone and a bacterial suspension of E. coli reduced the synthesis of LTB4. Estradiol had no effect on LTB4 synthesis at the end of the postpartum period. These results suggest that LTB4 may play an important role in both placental separation and uterine involution in cattle and LTB4 synthesis may be modulated by endocrine and bacterial factors.

Epidermal growth factor (EGF)-like activity was measured in mares' colostrum and milk by radioreceptor assay. Milk samples were collected from 22 mares 1 or more times during early lactation. Samples of colostrum were taken after parturition and before the foal first suckled (presuckle), within 6 hours after the foal first suckled (postsuckle), and on days 1, 2, 4, and 8 of lactation. In the 5 mares from which milk samples were obtained at each sampling time, presuckle colostral mean EGF-like activity (17.8 ng/ml) was greatest (P < 0.05). The mean values for EGF-like activity at all other sampling times were not significantly different from each other (postsuckle colostrum, 9.7 ng/ml; day 1, 9.6 ng/ml; day 2, 8.5 ng/ ml; day 4, 8.0 ng/ml; day 8, 7.8 ng/ml).

Studies were undertaken to assess the chicken embryo and newly hatched chicken as models for studying the effects of bone-active agents. Initially, 1,25-dihydroxycholecaliferol (1,25[OH]2D3), sodium fluoride (NaF), parathyroid extract, epidermal growth factor, and prostaglandin E2, were tested for lethality over a broad dose range. One or 3 injections of 1,25(OH)2D3 into the yolk sac of chicken embryos resulted in death of embryos given greater than 0.1 ng/injection, whereas 0.01 ng was tolerated by the embryos. Administering 1,25(OH)2D3 intraperitoneally to newly hatched chickens as a single injection or weekly for 3 weeks resulted in no deaths at doses up to 50 ng. One or 3 IV injections of less than 400 micrograms were tolerated by the embryo. Giving chickens feed and water containing 2.4 g of NaF/kg was lethal but no deaths occurred when chickens were given feed containing less than 1.2 g of NaF/kg. Mortality associated with the administration of epidermal growth factor to embryos was inconsistent, in that death occurred in embryos given a single injection of greater than 250 ng, but no deaths occurred in embryos given 3 injections at similar doses. Parathyroid extract and prostaglandin F2 were not lethal when administered to embryos and chickens in a single-injection or multiple-injection regimen. Overall, lethality in chicken embryos given a particular agent reflected the dose of bone-active agent injected, rather than the number of injections. Three of the bone-active agents were selected to characterize their microscopic bone effects in chicken embryos and chickens. Administration of 1,25(OH)2D3 to embryos on day 14 at doses of 100, 10, 1, and 0.1 ng led to subperiosteal hyperosteoidosis in all 5 of the tibiotarsi examined from the high-dose (100 ng) group necropsied on day 18 of incubation. Three of 5 of the tibiotarsi from the 10-ng treatment group were similarly affected. Bone effects were noticed in chickens hatched from the aforementioned treatment groups or in chickens given 1,25(OH)2D3 intraperitoneally and examined at 3 and 6 weeks of age. Administration of NaF to chicken embryos on the 10, 12th, and 14th days of incubation via the IV route at doses of 160, 80, 40 and 20 micrograms/embryo led to subperiosteal hyperosteoidosis in tibiotarsi from 3 of 10 embryos (examined at 18 days of incubation) from the 2 high-dose groups. Tibiotarsi of chickens from this treatment group were microscopically normal at 3 weeks after hatching. When newly hatched chickens were given a diet containing NaF at dosages of 1.2 g/kg, 0.6 g/kg, and 0.3 g/kg, a dose-dependent increase in osteoid was seen at 3 and 6 weeks. In addition, cortical thinning and expansion of the medullary canal were observed only at 3 weeks. In contrast to the effects observed with 1,25(OH)2D3 and NaF, parathyroid extract caused no microscopic bone alterations when given to embryos or chickens. Overall, the bone alterations in the embryo were attributed to increased subperiosteal osteoid formation and defective mineralization. These findings were consistent with known effects of NaF and 1,25(OH)2D3 on bone, and they establish the chicken embryo as a sensitive model for studying bone-active agents.

The effect of ingested epidermal growth factor (EGF) on the small intestinal mucosa of conventionally weaned pigs was determined. At 21 days of age, 39 pigs were randomly distributed into suckling and weaned treatment groups that were administered 124 micrograms of EGF, 372 micrograms of EGF, or the dosing compound daily. Fecal water content was determined daily. On postweaning days 0, 3, 6, and 9, representative pigs from each group were euthanatized, and jejunal mucosa samples were collected for determination of villus-to-crypt ratio, total protein content, disaccharidase activities, and microbiological populations. At postweaning day 3, the 372-micrograms dose of EGF significantly (P less than or equal to 0.05) increased jejunal lactase and sucrase activities in the weaned pigs. Increased lactase activity was not greater than that of the suckling pig controls, whereas sucrase activity was significantly (P less than or equal to 0.05) higher than that of the suckling pig controls. Significant changes were not observed in villus-to-crypt ratio, mucosal protein content, or disaccharidase activities on other collection days.

Epidermal growth factor was injected intracamerally into the anterior chamber of the right eye of 9 cats. The central portion of the cornea in 8 of the 9 cats that had been cryoinjured. Effect of epidermal growth factor on the repair of endothelial cells in cats was evaluated by endothelial specular microscopy. Endothelial cell density and corneal thickness were studied quantitatively, as a measure of endothelial cell function. The repair process also was evaluated qualitatively by studying morphologic changes, developing as a result of reendothelialization and return to normal function. Seemingly, differences between rate of healing of cryoinjured eyes injected with epidermal growth factor and that in nontreated eyes were not significant (P = 0.86). The endothelial repair process was characterized by enlargement and migration of adjacent noninjured cells.