Growth hormone receptor and insulin-like growth factor-I immunoreactivity in osteoclast-like cells during tooth eruption in the toothless (Osteopetrotic) rat following treatment with colony-stimulating factor-1

In the toothless (tl/tl) osteopetrotic rat, teeth form but fail to erupt. Treatment of tl/tl rats with colony-stimulating factor-1 (CSF-1) activates bone resorption by osteoclasts, permits tooth eruption, and up-regulates the immunoreactivity of bone marrow mononuclear cells to growth hormone receptor (GHr) and insulin-like growth factor (IGF)-I. This study examined the distribution of tartrate-resistant acid phosphatase (TRAP) and immunoreactivity for GHr and IGF-I in osteoclast-like cells located on the alveolar bone margin, adjacent to the lower first molar crown, in 14-day-old normal and tl/tl rats, following treatment with CSF-1. Osteoclast-like cells demonstrated a positive reaction for TRAP, GHr, and IGF-I in all groups. However, in tl/tl tissue, osteoclast-like cells were generally negative for GHr. There was no significant difference in the total number of TRAP, GHr, and IGF-I-positive osteoclast-like cells on the adjacent bone margin in normal, normal treated with CSF-1, and tl/tl rats. CSF-1 treatment of the tl/tl rat significantly increased the total number of osteoclast-like cells, which were positive for TRAP (p < 0.001), GHr (p < 0.05) and IGF-I (P < 0.01).

Carboxy-fluorescein diacetate, succinimidyl ester labeled papillomavirus virus-like particles fluoresce after internalization and interact with heparan sulfate for binding and entry

Human papillomaviruses (HPVs) infect epithelial cells and are associated with genital carcinoma. Most epithelial cell lines express cell-surface glycosaminoglycans (GAGs) usually found attached to the protein core of proteoglycans. Our aim was to study how GAGs influenced HPV entry. Using a human keratinocyte cell line (HaCaT), preincubation of HPV virus-like particles (VLPs) with GAGs showed a dose-dependent inhibition of binding. The IC50 (50% inhibition) was only 0.5 mug/ml for heparin, 1 mug/ml for dextran sulfate, and 5-10 mug/ml for heparan sulfate from mucosal origin. Mutated chinese hamster ovary (CHO) cell lines lacking heparan sulfate or all GAGs were unable to bind HPV VLPs. Here we also report a method to study internalization by using VLPs labeled with carboxy-fluorescein diacetate, succinimidyl ester, a fluorochrome that is only activated after cell entry. Pretreatment of labeled HPV VLPs with heparin inhibited uptake, suggesting a primary interaction between HPV and cell-surface heparan sulfate. (C) 2003 Elsevier Science (USA). All rights reserved.

Characterization of Treponema phagedenis-like spirochetes isolated from papillomatous digital dermatitis lesions in dairy cattle

Four spirochete strains were isolated from papillomatous digital dermatitis (PDD) lesions in Iowa dairy cattle and compared with two previously described spirochete strains isolated from dairy cattle in California. These six strains shared an identical 16S ribosomal DNA sequence that was 98% similar to Treponema phagedenis and 99% similar to the uncultivated PDD spirochete sequence DDLK-4. The whole-cell protein profiles resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of these six strains were similar. However, these strains showed differences in the antigenic diversity of lipopolysaccharide (LPS). Genetic diversity was also detected by pulsed-field gel electrophoresis of genomic DNA digests, revealing differences among five of the six strains. Serum immunoglobulin G antibodies from dairy cattle with active PDD lesions reacted with the LPS of all but one PDD spirochete strain. Likewise, peripheral blood mononuclear cells from cattle with active PDD lesions produced blastogenic responses to one of the two California isolates. Both antibody and lymphocyte blastogenic responses were reduced in convalescent dairy cattle, suggesting the immune response to these spirochetes has short duration. These results demonstrate genetic and antigenic diversity among T. phagedenis-like treponemes and provide further evidence for the involvement of these spirochetes in the pathogenesis of PDD.