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Foal heat diarrhea (FHD) is a major factor in the management of foals between 2 and 3 wk of age. The objective of this on-farm study was to determine the efficacy of postpartum anthelmintic treatment of mares for reducing the incidence and/or the severity of FHD in foals caused by parasitic infestation. Twenty-four Quarter Horse mares and their foals were alternately assigned to a treated or non-treated group according to expected foaling date. Treatment consisted of oral administration of Zimectrin® (Farnam Companies, Inc., Phoenix, AZ) to the dam within 12h post-foaling. From d l through 25, foals were weighed, and vital signs and severity or absence of diarrhea were recorded. Incidence scores of 0 to 3 were assigned to each foal based on severity of diarrhea: 0 = no affliction and 3 = severe, watery diarrhea. There was no difference in incidence scores because of treatment; however, there was a trend for foals from treated mares to experience more severe diarrhea with a shorter duration. There was no difference in BW gain related to treatment or nontreatment of mares. Postpartum administration of Zimectrin to mares did not significantly decrease the incidence or severity of diarrhea in foals. Additionally, it did not affect growth rate of foals. The trend for foals from treated mares to have a shorter duration of FHD may be beneficial to farm managers who spend time and money treating and cleaning foals.

Background:Because of the wide variation in the ability of human demineralized freeze‐dried bone allograft (DFDBA) to reproducibly induce new bone formation, there is a need for a reliable measure of bone induction activity. In this study we examined an immature osteoprogenitor cell line for its potential utility in measuring the activity of DFDBA in vitro. Methods:We characterized the response of 2T9 cells, an immature osteoprogenitor cell line derived from the calvariae of transgenic mice containing the SV40 T‐antigen driven by the mouse bone morphogenetic protein (BMP)‐2 promoter, to recombinant human BMP‐2 by measuring alkaline phosphatase specific activity, osteocalcin production, and matrix mineralization. Responses were compared to those obtained with 1,25‐(OH)2D3. In addition, 2T9 cells were cultured with active or inactive human DFDBA in the presence or absence of BMP‐2. We also tested the hypothesis that radio‐opacity of tissue following implantation of DFDBA in vivo correlates with the ability of human DFDBA to induce new bone. DFDBA from 9 different donors, stratified by age, were implanted subcutaneously in the thorax of 18 nude (nu/nu) mice. Tissue was harvested at 36 days postoperatively and examined histologically and biochemically for calcium and phosphorus uptake. Results:2T9 cells exhibited a dose‐ and time‐dependent response to soluble BMP‐2. Proliferation was decreased and alkaline phosphatase activity, osteocalcin production, and mineralized nodule formation were increased. The effects were dose‐ and time‐dependent. Peak effects on alkaline phosphatase and osteocalcin were noted on day 8, whereas mineral deposition did not begin to occur until day 12. 1,25‐(OH)2D3did not regulate these effects unless used with BMP‐2. When the cells were exposed to active or inactive DFDBA in the presence or absence of BMP‐2, no effect on 2T9 cell differentiation was observed. This indicated that DFDBA released no soluble factors with bone inductive ability and that if any active factors were adsorbed to the DFDBA, they were inactivated. When DFDBA was implanted subcutaneously in the thorax of nude mice, there was no histologic evidence of new bone formation. However, there was a donor age‐dependent decrease in Ca and P uptake of the implanted tissue, reflecting a donor age‐dependent decrease in remineralization of DFDBA. Conclusions:These data indicate that cell culture assays like the one used in this study may not be appropriate indicators of bone induction ability by DFDBA since soluble factors may not be responsible for bone induction in vivo. Nonetheless, in vitro assays are still needed. While Ca and P uptake by DFDBA‐implanted tissue in the present study correlated with the age‐dependent decrease in bone induction at intramuscular sites in a previously reported study, these data show that early x‐rays may actually detect remineralization and not new bone formation. Thus, assessment of bone induction ability may still depend on histologic analysis of animal models. J Periodontol 1999;70:353‐363.

Transforming growth factor ß (TGF ß) is one of the most abundant of the known growth regulatory factors stored within the bone matrix. When bone is resorbed, TGF ß is released in an active form and is a powerful bone growth stimulant. When injected into the subcutaneous tissue over the calvarial surface of rodents, it rapidly causes proliferation of the periosteal layer and accumulation of new woven bone. In this report, we describe the effects of TGF ß1on first subcultures of fetal rat osteoblasts obtained from calvarial bones and cultured from confluence with ascorbic acid and ß glycerophosphate. Under these conditions, nodules with characteristics of normal bone appear by day 8. Similar to experiments described by Antosz et al., TGF ß added to confluent cultures inhibited the formation of bone nodules. Both the number and total area of the nodules were quantitated and shown to be completely inhibited by 2 ng/ml of TGF ß1. TGF ß also impaired the expression of genes associated with bone formation, including type I collagen, alkaline phosphatase, osteopontin, and osteocalcin. TGF ß also inhibited the expression of mRNA for the bone morphogenetic protein 2 (BMP 2). These results, showing suppression of markers representative of osteoblast differentiation, suggest that the effects of TGF ß to stimulate bone formation in vivo are not likely a result of effects on differentiated mineralizing osteoblasts but, as suggested by previous studies, more likely are caused by effects on osteoblast precursors. These results also suggest that endogenous BMP 2 expression in fetal rat calvaria cells is important for bone cell differentiation.

Periodontal ligament(pdl) cells are thoughtto be important for establishing and maintaining a stable interface between bone and teeth. In addition, PDL cells are thought to play critical roles in both the pathogenesis of periodontal disease and the regeneration of periodontal ligament tissues. The purpose of this study was to develop a continuous or stable human PDL cell line as an in vitro model for the investigation of cellular mechanisms involved in periodontal regeneration and destruction. Human PDL cells, derived from a primary cell culture, were transfected with simian virus 40 (SV40) T antigen‐containing virus with a neomycin resistance gene. The transformed cells expressed the SV40 T antigen mRNA as assayed by reverse transcription polymerase chain reaction (RT‐PCR). This cell line was also characterized for morphological changes and growth characteristics compared to primary PDL cell cultures. The transformed cells were shown to form a multilayer pattern and distinct colonies on tissue culture surfaces. However, no colony formation was found in soft agar. The transformed PDL cell line was found to have a greater rate of proliferation in 10% fetal bovine serum than primary culture, and continued to proliferate in low serum concentrations capable of producing quiescence in primary cells. Interleukin‐1β (IL1β) was shown to produce a 7‐fold elevation in collagenase (MMP‐1) mRNA levels, consistent with primary PDL cells. In addition, IL‐1β was shown to produce a decrease in alkaline Phosphatase activity in a concentration‐dependent manner. The transformed cell line has been maintained for over 30 generations of cell culture. In conclusion, a stable human PDL cell line has been established to serve as a model for future in vitro investigations into periodontal pathogenic mechanisms and to evaluate therapies directed at the regeneration of periodontal ligament. J Periodontol 1997;68:1054–1062.

In addition to structural proteins of bone, such as type I collagen, bone cells synthesize a number of growth regulatory peptides that are also stored in the bone matrix, presumably as a consequence of local production by osteoblasts. Among the bone growth regulatory peptides found in the bone matrix are the recently described bone morphogenetic proteins (BMPs). These factors were purified from bone matrix by their capacity to stimulate ectopic bone formation, but it is not known whether they are produced by normal bone cells and influence normal bone formation. To determine whether they are expressed by normal osteoblasts during differentiation, we used the technique of prolonged primary culture of fetal rat calvarial osteoblasts. These cultures have been shown to be an informative model for studying expression of bone‐related genes by cultured osteoblasts, since specific genes are expressed as the cells undergo proliferation and differentiation. We found that the bone morphogenetic proteins 1, 2, 4, and 6 are expressed by cultures of fetal rat calvarial osteoblasts before they form mineralized bone nodules and as they express alkaline phosphatase, osteocalcin, and osteopontin. This model can be used for study of regulation of expression of bone morphogenetic proteins by osteoblasts.