Bonnie C. Ford

Effect of fibroblast growth factors 1, 2, 4, 5, 6, 7, 8, 9, and 10 on avian chondrocyte proliferation

It has been demonstrated that fibroblast growth factor receptors are key regulators of endochondral bone growth. However, it has not been determined what fibroblast growth factor ligand(s) (FGFs) are important in this process. This study sought to determine whether FGFs 1, 2, 4, 5, 6, 7, 8, 9, and 10 were capable of stimulating avian chondrocyte proliferation in vitro. We have found that FGFs 2, 4, and 9 strongly stimulate avian chondrocyte proliferation while FGFs 6 and 8 stimulate proliferation to a lesser extent. RT‐PCR indicates that FGF‐2 and FGF‐4 are expressed in the postnatal avian epiphyseal growth plate (EGP) while FGF‐8 and FGF‐9 are not. Thus, FGF‐2 and FGF‐4 stimulate chondrocyte proliferation and are both present in the EGP. This suggests that FGF‐2 and FGF‐4 may be important ligands, in vivo, for the regulation of endochondral bone growth. These observations coupled with our observation that multiple avian FGF receptors (Cek1, Cek2, Cek3, and FREK) are expressed in proliferative chondrocytes highlights the complexity of FGF signaling pathways in postnatal endochondral bone growth. J. Cell. Biochem. 84: 359–366, 2002.

Parathyroid hormone‐related peptide expression in the epiphyseal growth plate of the juvenile chicken: Evidence for the origin of the parathyroid hormone‐related peptide found in the epiphyseal growth plate

Parathyroid hormone‐related peptide (PTHrP) has been shown to be essential for normal endochondral bone formation. Along with Indian hedgehog (Ihh), it forms a paracrine regulatory loop that governs the pace of chondrocyte differentiation. However, the source of PTHrP for this regulatory loop is not clear. While one hypothesis has suggested the periarticular perichondrium as the source of PTHrP for growth plate regulation, other data utilizing immunohistochemistry and in situ hybridization would indicate that growth plate chondrocytes themselves are the source of this peptide. The data described in this report supports the view that postnatal growth plate chondrocytes have the ability to synthesize this important regulatory peptide. Immunohistochemistry of tissue sections showed that PTHrP protein was evident throughout the chick epiphysis. PTHrP was seen in chondrocytes in the periarticular perichondrium, the perichondrium adjacent to the growth plate, the prehypertrophic zone of the growth plate, and the hypertrophic zone of the growth plate. However, cells in the proliferative zone, as well as some chondrocytes in the deeper layers of articular cartilage were predominantly negative for PTHrP. PTHrP was detected by Western blotting as a band of 16,400 Da in extracts from hypertrophic chondrocytes, but not from proliferative cells. RT‐PCR detected PTHrP mRNA in both proliferative and hypertrophic growth plate chondrocytes, as well as in articular chondrocytes. PTH/PTHrP receptor mRNA was detected by Northern blotting in growth plate, but not articular chondrocytes. Thus, we conclude that most of the PTHrP present in the epiphyseal growth plate of the juvenile chick originates in the growth plate itself. Furthermore, the presence of large amounts of PTHrP protein in the hypertrophic zone supports the concept that PTHrP has other functions in addition to regulating chondrocyte differentiation. J. Cell. Biochem. 80:504–511, 2001.

Comparative assessment of bone among wild-type, restricted ovulator and out-of-production hens

1. The aim of this study was to assess bone characteristics in restricted ovulator (RO) hens. These hens generally are unable to ovulate due to a point mutation in the oocyte VLDL receptor gene whose protein product mediates the uptake of yolk precursors. Because these hens do not have the cyclic calcium (Ca) metabolism associated with egg formation, they could be a useful model for studying bone metabolism. 2. RO hens had greater humerus, femur and tibia ash concentrations than wild-type (WT) and out-of-production (OP) hens. Bone mineral content and density obtained with dual-energy X-ray absorptiometry (DXA) were highly correlated with the results of conventional bone assays. 3. Gross and histological examination of the femurs confirmed the presence of extremely dense medullary bone deposition in the RO hens. However, the composition of non-collagenous protein extracts of medullary bone was similar for the two genotypes. 4. Analysis of medullary bone extracts for glycosaminoglycans (GAG) confirmed the presence of large amounts of keratan sulphate (KS) in the matrix of medullary bone. 5. Plasma Ca, total GAG and KS concentrations of RO hens were markedly higher than WT and OP hens. The changes in plasma calcium and keratan sulphate are probably a reflection of elevated Ca-binding yolk precursor molecules and intensive medullary bone formation in response to increased plasma oestrogen observed by others in RO hens.

The use of growth factors in the proliferation of avian articular chondrocytes in a serum-free culture system.

The purpose of this research was to develop a serum-free culture system for the proliferation of articular chondrocytes. Various growth factors and hormones were tested for their ability to stimulate avian articular chondrocyte proliferation in a defined, serum-free media. Multiple members of the fibroblast growth factor (FGF) family (FGFs: 2, 4, and 9), insulin-like growth factor-1 (IGF-1) and transforming growth factor β (TGF-β) significantly stimulated 3H-thymidine uptake by chondrocytes grown in an adherent serum-free, culture system. Double or triple combinations of these mitogenic growth factors further stimulated cell proliferation to levels that were equivalent to, or surpassed those of cells grown in serum. Although proliferation was maximally stimulated, chondrocytes grown in the presence of FGF-2, IGF-1, and TGF-β, began to exhibit changes in morphology and collagen II expression declined. This culture system could be used to rapidly expand a population of articular chondrocytes prior to transferring these cells to a non-adherent culture system, which could then stabilize the chondrocyte phenotype and maximize matrix synthesis and integrity.

Cesium-134 and Cesium-137 in Honey Bees and Cheese Samples Collected in the U.S. After the Chernobyl Accident

Abstract As a result of the Chernobyl accident on April 25, 1986, possible radioactive contamination of honey bees and cheese sampled in several areas of the United States were measured. Of bees collected in May and June of 1986 in both Oregon and New York, only those from Oregon showed detectable levels of cesium-134 ( T 1 2 = 2.05 years ), a radionuclide which would have originated from the Chernobyl incident. Cheese produced in Oregon and New York before the accident showed only cesium-137 ( T 1 2 = 30.23 years ) but cheese produced afterwards (May and September, 1986) in Oregon contained cesium-134. Cheese produced in Ohio and California at the time of the accident and thereafter contained only cesium-137. In general, the levels of radioactivity were higher in the West coast samples as compared to those taken in the East. The levels of radioactivity detected were considered to be toxicologically of no consequence.