Bone-lining cells

ParfittAM (2001) The bone remodeling compartment a circulatory function for bone lining cells. J Bone Miner Res 16 1583-1585... 

Figure 1. Diagram of a thin bone trabecula (5) showing the four types of bone cells. Osteoblasts (8) and their precursors (7) are shown on the upper surface over a layer of uncalcified osteoid matrix (9), os-teocytes (6) are shown in their lacunae, an osteoclast (1) and a bone lining cell (3) are shown on the lower surface. Capillaries (4), containing red blood cells in their lu-mina, and a fibroblast (2) are shown near the trabecula. Adapted from Krstic (1978).

Rubinacci, A., Villa, I., et al. (1998) Osteocyte-bone lining cell system at the origin of steady ionic current in damaged amphibian bone. Calcified Tissue International 63 331-339... 

Bone resorption in response to continuous mechanical deformation appears to be regulated by cells of osteoblast lineage such as preosteoblasts, osteoblasts, bone lining cells and osteocytes, and stretch-enhanced, osteoclastlike cell formation involves prostaglandins, but not PGE2 (Soma et al., 1996). Stretch-induced increases in osteopontin and osteonectin were inhibited by addition of the calcium channel antagonist nifedipine suggesting an important role for L-type calcium channels in early mechanical strain transduction pathways in osteoblasts. 

The estimated 50-year dose commitment from plutonium for people in the north temperate zone due to atmospheric tests conducted before 1973 is 0.2 mrad (0.002 mGy) to the bone lining cells (Eisenbud 1987). [The gray is an SI unit of absorbed dose and is equal to 0.01 ram.] The average annual dose equivalent from all background radiation to an individual residing in the United States is estimated to be 360 mrem (3.6 mSv) (NCRP 1987). [The sievert is an SI unit of dose equivalent and is equal to 0.01 rem.]... 

Another dideoxypyrimidine nucleoside active against human immunodeficiency vims is 3 -azido-2/3 -dideoxyuridine [84472-85-5] (AZDU or CS-87, 64) C H N O. Since its synthesis, (167) CS-87 has been identified as a promising antiHIV agent (168) and is currentiy undergoing phase I clinical trials in patients with AIDS and AIDS-related complex. It appears to be less potent than AZT against HIV in a peripheral blood mononuclear (PBM) cell screening system and in MT-4 cell lines. This lower activity in PBM cells appears to be related to a lower affinity of CS-87 for the enzyme responsible for its initial phosphorylation (169). However, CS-87 has significantly lower toxicity on bone marrow cells than AZT (170) and penetration of the CNS as a 5 -dihydropyridine derivative. 

Osteoblasts are the primary cells responsible for bone formation. They are derived from mesenchymal (stromal) cells that first differentiate into pre-osteoblasts and then into mature, bone matrix producing osteoblasts. Inactivated or resting osteoblasts become lining cells and thus a reservoir for bone forming cells to be activated at the next remodelling cycle. Osteoblasts trapped and embedded in the mineralised matrix are called osteocyts, and are important for many properties of living bone. 

Catechol (approx. 10 mol/L) inhibited the growth of bone-marrow cells from female C57BL/6 x DBA/2 mice (Seidel et al., 1991) and from male C57 and SW mice (Neun et al., 1992). Catechol (25, 50, 75 or 100 mg/kg bw, single intraperitoneal administration) decreased the incorporation of Fe to erythrocytes in a dose-dependent fashion in female Swiss mice, when administered with phenol (50 mg/kg bw, single intraperitoneal administration) (Snyder et al., 1989). Catechol induced apoptosis in the human leukaemia cell line HL60 at concentrations (50 pmol/L) at which necrosis was not observed (Moran et al., 1996). On the other hand, catechol (> 0.5 pmol/L) prevented elimination by apoptosis of G418-resistant, transformed Swiss 3T3 M X Cll cells by co-cultured TGF-P-treated C3H I OT A cells (Schaeffer et al., 1995). 

Chlorodifluoromethane is mutagenic to Salmonella typhimurium but it did not induce either mutation or gene conversion in Saccharomyces cerevisiae. Chlorodifluoromethane did not induce mutations at the hprt locus or imscheduled DNA synthesis in mammalian cell lines in the presence or absence of an exogenous metabolic activation system. In vivo, it did not induce chromosomal aberrations in bone-marrow cells or dominant lethal effects (lARC, 1987b). These conclusions are supported by a more recent review (WHO, 1991). 

Chloroethane was mutagenic to bacteria and at the hprt locus in a study with the Chinese hamster ovary cell line, but not did not induce transformation in BALB/c 3T3 cells. In B6C3F] mice exposed by inhalation, it did not induce either unscheduled DNA synthesis in hepatocytes or micronuclei in bone-marrow cells. 

Compound 2 inhibited murine and human bone marrow cell colony formation with and ID50 of 0.1-1 pg/ml, with complete inhibition occurring at 10-100 pg/ml. It was found to be more potent than vinblastine or taxol, with an IC50 of 0.23 nM against human ovarian cancer and colon cancer cell lines. Furthermore, dolastatin 10 was shown to be powerfully effective at binding to tubulin, inhibiting polymerization and it also non-competitively inhibits the binding of vinca alkaloids to tubulin,... 

Green S, Moreland, Sheu C. 1977. Cytogenic effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin on rat bone marrow cells. Washington, DC Food and Drug Administration. FDA by-lines 6 292. 

There is some evidence for the antimuta-genic effects of vanillin for example, in suppressing chromosomal damage induced by methotrexate in the Chinese hamster V79 cell line (Keshava et al, 1998). Inouye et al. (1988) reported the suppression of the induction of micronuclei by mitomycin C (MMC) in mouse bone marrow cells by post-treatment with vanillin. Post-treatment with vanillin at 500mg/kg caused about 50% decrease in the frequency of micronu-cleated polychromatic erythrocytes (MN-PCEs). The suppressant effect was not due to a delay in the formation of MN-PCEs but to the cytotoxic action of vanillin. Vanillin acts as an anticlastogenic factor in vivo. 

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