Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:APRD00369 (ROS)
 19,271 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Disks from bovine ROS undergo a rapid shrinkage when flash illuminated with green light (Uhl, R., et al. (1977) Biochim. Biophys. Acta 469. 113-122). This can be monitored as a light scattering transient, referred to as the P signal. In this paper the P signal is studied at various temperatures and pH. The temperature dependence of the kinetics reveals that "P" consists of two sequential reaction steps. Both appear to occur within the receptor molecule rhodopsin. The actually observed event, the shrinkage of the disk, is therefore not rate limiting under the tested conditions. Both steps of "P" take place while there is only one spectroscopically detectable reaction of the rhodopsin molecule, the metarhodopsin I-metarhodopsin II transition. This implies that there are intermediates of the rhodopsin photolytic cycle which are not evident as spectroscopically separate species. The amplitude of "P", i.e., the extent of the disk shrinkage, is independent of the state of the equilibrium between the two photoproducts absorbing at 478 and 380 nm respectively and called MI and MII. A scheme is suggested in which the irreversible decay of MI (478) triggers the disk shrinkage (and maybe transduction), and in which there is an equilibrium between MII (380) and a proposed isochromic photoproduct MI' (478).
Biochemistry 1978 Dec 12
PMID:On the light-stimulated coupling between rhodopsin and its disk membrane environment. 72 4

Experiments with 73 GrCh rabbits showed, that both homologous and heterologous (bovine) photoreceptor outer segments (ROS) induce chorioretinitic diseases of the same kind. The findings refer to questions of localization and efficiency of homologous and heterologous (bovine) pathogenic ROS antigens.
Albrecht Von Graefes Arch Klin Exp Ophthalmol 1975 Dec 04
PMID:[Experimental chorioretinitis in rabbits induced by homologous and heterologous photoreceptor outer segments (author's transl)]. 108 73

In vitro studies were carried out to determine if reactive oxygen species modified DNA molecules are the preferred antigen for anti-DNA antibodies found in SLE sera. Reactive oxygen species were generated by 254 nm irradiation of hydrogen peroxide. Single stranded breaks, decrease in Tm and modification of adenine (21.7%) and thymine (48%) were the major effects observed on native DNA fragments of 300 bp in length. The ROS-modified DNA showed increased binding with naturally occurring anti-DNA autoantibodies as compared to unmodified DNA fragments. These results were substantiated by competition ELISA. Measurement of binding with DNA fragments of varying size revealed considerably increased binding as the fragment size increased from 50 bp to 800 bp. The relative affinity of anti-DNA IgG for ROS-modified and native DNA fragments of 300 bp were in the order of 6.26 x 10(-8) M and 4.07 x 10(-8) M, respectively.
Immunol Lett 1992 Dec
PMID:Reactive oxygen species modified DNA fragments of varying size are the preferred antigen for human anti-DNA autoantibodies. 128 55

Bone is a tissue that responds to mechanical load by changing its internal architecture. However, the mode of transmission of mechanical stimuli into biological signals and the effect of load at the cellular level are still not clear. An in vitro system, a Flexercell Strain Unit, was used to apply cyclic load to osteoblast-like cells in culture. In the first series of experiments, ROS 17/2.8 rat osteosarcoma cells, cultured on Flex I, flexible bottomed culture plates, were subjected to a 0.05 Hz, 0.24 STRAIN cyclic load regime for 3 and 7 days, in vitro. One group subjected to load received verapamil, a calcium channel blocker, throughout the experimental period. A second group was exposed to load but received no verapamil. A third group had no drug or load and a fourth group had no load but received verapamil. Cultures were incubated for 24 hours prior to collection with 10 microCi of 45CaCl in the medium, then well bottoms were divided to yield outer (maximum) and inner (minimum) load zones for assay of radioactivity. The effect of verapamil during a 7-day loading period was studied by adding the drug to individual cultures at daily intervals. Results indicated that mechanical loading stimulates calcium incorporation in ROS 17/2.8 cell cultures by day 7 but not by day 3. Only early verapamil addition decreased load-induced calcium incorporation when drug was added prior to day 4. If verapamil was added after 4 days, the channel blocker did not diminish load-induced calcium incorporation.
Matrix 1992 Dec
PMID:Verapamil decreases cyclic load-induced calcium incorporation in ROS 17/2.8 osteosarcoma cell cultures. 128 12

Osteoblasts play a pivotal role during the bioresponse of bone to agents that stimulate bone resorption and/or inhibit bone formation including hormones, polypeptide growth factors, and cytokines. We examined the cytokines interleukin-1-beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) for their effects on osteoblastic proliferation and development and expression of alkaline phosphate and the osteoblast-specific protein osteocalcin in a mineralizing environment. Primary rat osteoblast-like cells (ROB) and osteoblastic cell lines derived from rat (ROS 17/2.8) and human (MG-63) osteosarcomas were studied. IL-1 beta and TNF-alpha were chosen because of their critical importance during the host response to local inflammatory stimuli. Qualitatively similar two- to threefold inhibition of osteocalcin synthesis by IL-1 beta and TNF-alpha were observed in all three postconfluent bone-forming model systems. Because of the readily measurable concentrations of osteocalcin produced in our culture protocol, it was not necessary to enhance osteoblastic synthesis of osteocalcin by supplementation with 1,25(OH)2-vitamin D3, a treatment which exerts pleiotropic effects on osteoblasts. Under the constraints of our protocol, where alkaline phosphatase and mineralization were already elevated at the 14-day onset of treatment, neither of these phenotypic properties was sensitive to a three-day cytokine exposure. Differences were noted in proliferation, where only TNF-alpha stimulated DNA synthesis in ROB cells, while both cytokines stimulated MG-63 cells. IL-1 beta and TNF-alpha failed to alter ROS 17/2.8 DNA synthesis except at the highest doses (25 pM IL-1 beta and 1 nM TNF-alpha) where inhibition was observed. These results further support the view that cytokine-mediated osteoblastic regulation can be relatively selective.
Inflammation 1992 Dec
PMID:Effects of interleukin-1 beta and tumor necrosis factor-alpha on osteoblastic expression of osteocalcin and mineralized extracellular matrix in vitro. 145 94

We have determined the dose-response of 1,25-dihydroxyvitamin D-3 (1,25-(OH)2D3) on the intracellular free calcium-ion concentration ([Ca2+]i) in the osteoblastic osteosarcoma cells, ROS 17/2.8, using 19F-NMR and the intracellular divalent cation indicator, 1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetraacetic acid (5F-BAPTA). The dose-response demonstrated an inverted U-shaped relationship with maximal elevation of [Ca2+]i at doses of 1 to 10 nM 1,25-(OH)2D3. At 10 nM, 1,25-(OH)2D3 elevated the [Ca2+]i from a control level of 118 +/- 4 nM to a peak value of 237 +/- 8 nM within 40 min. 1,25-(OH)2D3 also increased the initial rate of Ca2+ influx into ROS 17/2.8 cells, measured by 45Ca uptake, with a dose-response relationship which paralleled its effect on [Ca2+]i. Treatment of ROS 17/2.8 cells with Pb2+ at 1 and 5 microM significantly increased [Ca2+]i but significantly reduced the 1,25-(OH)2D3-induced elevation of [Ca2+]i. Simultaneous treatment of naive cells with 1,25-(OH)2D3 and Pb2+ produce little reduction of 1,25-(OH)2D3-induced 45Ca uptake while 40 min treatment with Pb2+ before addition of 1,25-(OH)2D3 significantly reduced the 1,25-(OH)2D3-induced increase in 45Ca influx. These findings suggest that Pb2+ acts by inhibiting 1,25-(OH)2D3-activation of Ca2+ channels and interferes with 1,25-(OH)2D3 regulation of Ca2+ metabolism in osteoblastic bone cells.
Biochim Biophys Acta 1992 Dec 10
PMID:Lead inhibits 1,25-dihydroxyvitamin D-3 regulation of calcium metabolism in osteoblastic osteosarcoma cells (ROS 17/2.8). 146 69

PTH-related peptide (PTH-rP) has recently been discovered to exist in high concentrations in milk. The development of a commercial RIA for PTH-rP has allowed us to extend these studies. We measured the PTH-rP content of milk from 42 Jersey cows from a single farm in various stages of lactation. Colostrum (first milk) contained 56 +/- 12 ng/ml immunoreactive PTH-rP (iPTH-rP). The iPTH-rP contents of milk 1, 2, 3, 5, 7, and 9 months into lactation were 77 +/- 19, 59 +/- 14, 57 +/- 10, 106 +/- 11, 119 +/- 16, and 168 +/- 17 ng/ml, respectively. Plasma was obtained from 7 Jersey calves at birth and at intervals after the ingestion of colostrum. No iPTH-rP was detected in the plasma at birth. Two hours after the ingestion of colostrum, the iPTH-rP content of plasma was 81 +/- 25 pg/ml. The plasma iPTH-rP concentration continued to increase to 384 +/- 84 pg/ml at 7 h and peaked at 444 +/- 84 pg/ml 12 h after birth. Two calves were sampled through the 60th hour after birth, at which time plasma iPTH-rP was 483 +/- 36 pg/ml. The biological activity of the PTH-rP in milk and plasma was assessed by its ability to stimulate cAMP accumulation in ROS 17/2.8 cells. The specificity of this response was determined by the ability of antiserum to PTH-rP to block the activity. The biological activity of the milk samples was between 31-95% of the activity suggested by immunoassay. Biologically active PTH-rP could not be detected in any of the calf plasma samples. These results confirm the presence of biologically active PTH-rP in milk and suggest that the iPTH-rP is capable of being absorbed. However, our results indicate that the biological activity of the PTH-rP is nearly completely absent once in the systemic circulation.
Endocrinology 1991 Dec
PMID:Parathyroid hormone-related peptide content of bovine milk and calf blood assessed by radioimmunoassay and bioassay. 165 14

1 alpha,25-Dihydroxyvitamin D3 [1 alpha,25-(OH)2D3] rapidly increases cytosolic calcium in a variety of cell types. Although these rapid effects do not appear to directly involve genome activation, the requirement for the classic vitamin D receptor is unclear. Clonal rat osteosarcoma cells, ROS 17/2.8, respond to 1 alpha,25-(OH)2D3 with an increase in osteocalcin message but ROS 24/1 cells do not. The lack of the receptor for vitamin D in the ROS 24/1 cells has been confirmed by the absence of any detectable vitamin D-receptor complex binding to the vitamin D-responsive element (VDRE) of the osteocalcin gene and the absence of vitamin D receptor mRNA in the cells. Quin-2-loaded ROS 17/2.8 and ROS 24/1 cells were treated with 1 alpha,25-(OH)2D3 in the presence and absence of extracellular calcium and with the inactive epimer, 1 beta,25-dihydroxyvitamin D3 [1 beta,25-(OH)2D3]. The 1 alpha,25-(OH)2D3 increased cytosolic calcium in the ROS 17/2.8 and 24/1 cells after 5 minutes in a dose-responsive manner and in the presence and absence of extracellular calcium. Pretreatment of both cell lines with 1 beta,25-(OH)2D3 for 30 s blocked the hormone-induced rise in cytosolic calcium. The rapid effects of 1 alpha,25-(OH)2D3 on ROS cells with and without the vitamin D receptor and the ability of the inactive epimer to inhibit these effects indicate that the signaling system mediating the hormone's rapid actions is not the classic vitamin D receptor.
J Bone Miner Res 1991 Dec
PMID:1 Alpha,25-dihydroxyvitamin D3 rapidly increases cytosolic calcium in clonal rat osteosarcoma cells lacking the vitamin D receptor. 166 80

ROS 17/2.8 cells, a cloned rat osteoblastic osteosarcoma cell line, were found to be extremely sensitive to the lethal effects of cadmium and to synthesize little, if any, metallothionein in response to cadmium exposure. Culture of cells for 24 h in the presence of 1 microM 5-azacytidine, a cytidine analog, increased the inducibility of metallothionein by cadmium and significantly reduced (P less than 0.001) cytotoxicity. Anion exchange chromatographic analysis of cadmium binding to low molecular mass cytotoxicity. Anion exchange chromatographic analysis of cadmium binding to low molecular mass cytosolic proteins showed that cells treated with cadmium and 5-azacytidine expressed at least 2 isoforms of metallothionein. One isoform of metallothionein with a low affinity for cadmium was constitutively expressed by these cells. The association of poor inducibility of metallothionein by cadmium with extreme sensitivity of cells to cadmium emphasizes the role of this protein in the cellular response to this toxic metal. The modulation of metallothionein inducibility and sensitivity to cadmium by 5-azacytidine treatment suggest that metallothionein gene structure and regulation are altered in ROS 17/2.8 cells.
Toxicology 1990 Dec 17
PMID:Effect of 5-azacytidine on metallothionein inducibility and sensitivity to lethality of cadmium in rat osteosarcoma (ROS 17/2.8) cells. 170 34

Demineralized bone powder (DBP) has been shown to induce osteogenesis in a variety of bone defects and extra-osseous sites. Previous investigations have been carried out in animal models which are time-consuming and expensive. We studied the effect of DBP on well-established populations of osteoblast and non-osteoblast-like cells in culture to establish an inexpensive, efficient and reliable assay for bone induction. DBP and BP (non-demineralized powder), of particle size 38-53 microns, were prepared from rat long bones. ROS (rat osteosarcoma) 17/2.8 and ROS 24/1 cell lines were subcultured weekly. For both 17/2.8 (well differentiated) and 24/1 (poorly differentiated) cells, proliferation, i.e. cell count, was significantly greater in DBP enriched medium when compared with control or medium with BP. Cell counts for wells with BP were no different from controls. The increased cell count in DBP-enriched medium was significant on days 2-5 (peak effect 2-3 days). Alkaline phosphatase production reached peak levels after day 3 when proliferation was beginning to taper off. In this study a consistent increase in osteoblast proliferation and alkaline phosphatase production under the influence of DBP was demonstrated. The tissue culture assay for proliferation must now be correlated with bone induction in vivo. In future, the method may be useful for investigating the mechanism of bone induction.
Int J Oral Maxillofac Surg 1990 Dec
PMID:Effect of demineralized bone powder on osteoblast-like cells in culture. A potential rapid quality control assay. 170 40


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