Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Diphosphonates”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 703 records · Page 39Linked to original sources
PubMed1978

Resorption of bone implants. The effect of in vivo incorporation of a diphosphonate and fluoride on resorption.

Weanling isogenously related rats were divided into one control group, one group given a fluoride supplement of 100 parts/10(6) of F- in the drinking water, and a third group given 0.5 mg per kg body weight of phosphorus as dichloromethylene diphosphanic acid (Cl2MDP). The rats were labeled with 1 muCi per g body weight of 3H proline and 40 muCi of 45Ca. Four weeks after labeling, the animals were sacrificed and one scapula was implanted subcutaneously in the back of an isogenously related rat of the same age. The other scapula was stored in a freezer pending analysis. After another 4 weeks the implants were recovered and the radioactivity of each isotope was compared with that of the initially stored scapulae. A 30-40% loss of activity was found, reflecting a considerable loss of bone. However, this loss was significantly lower (P less than 0.01) when Cl2MDP was given to the donor animals, whereas fluoride treatment did not affect the resorption.

Animals↗
PubMed1985

Initial Tc-99m diphosphonate uptake in mineralized and demineralized bone implants in rats.

Radionuclide imaging has been suggested as a means to assess healing and viability of bone grafts and implants. This study deals with the in vivo uptake of 99mTc-MDP in the initial postoperative period in rats. Isogeneic or xenogeneic bone was implanted in subcutaneous pouches. The isogeneic grafts and implants were treated with saline or freeze-treated or demineralized. The xenogeneic implants consisted of Kiel bone or collagen sponge. One day after surgery, the accumulation of 99mTc after an intraperitoneal injection of 99mTc-MDP was seen in all grafts and implants containing bone mineral independent of prior treatment of the graft and implant. In implants composed of only the organic part of bone, no accumulation was observed. One prerequisite for accumulation of 99mTc-MDP is the presence of the inorganic phase. Thus, the interpretation of the initial postoperative scan is based on whether or not the graft or implant initially contained mineral.

Animals↗
PubMed2001

Quantitative studies of bone with the use of 18F-fluoride and 99mTc-methylene diphosphonate.

This article discusses methods for quantifying bone turnover based on tracer kinetic studies of the short-lived radiopharmaceuticals 99mTc-MDP and 18F-fluoride. Measurements of skeletal clearance obtained by using these tracers reflect the combined effects of skeletal blood flow and osteoblastic activity. The pharmacokinetics of each tracer is described, together with some of the quantitative tests of skeletal function that have been described in the literature. The physiologic interpretation of quantitative measurements of bone obtained with the use of short half-life radionuclides is discussed, and the advantages and limitations of 99mTc-MDP and 18F-fluoride are compared and contrasted. Currently, 18F-fluoride dynamic positron emission tomography (PET) is the technique of choice for physiologically precise quantitative studies of bone. However, comparable data could probably be obtained by using 99mTc-MDP if methods for single photon emission computed tomography (SPECT) quantitation were improved.

Bone Diseases, Metabolic↗
PubMed1980

[The kidneys and urinary tracts, as demonstrated by skeletal scintigraphy with 99m technetium-methyl diphosphonate (author's transl)].

The kidneys and urinary tracts were evaluated in 465 patients during the course of skeletal scintigraphy. In 45 cases suspicion was aroused and in 35 abnormalities were demonstrated in the kidneys, ureters or bladder. In six patients the suspicion of an abnormality could not be confirmed on pathologic, urologic or radiologic examinations. In four patients absence of activity in the kidneys was due to disseminated osteoblastic metastases. In half these cases (17 patients) these findings had not been suspected. The appearances of various renal and urinary tract abnormalities, as seen on a bone scintigram, have been classified into five categories. The most common appearance is that of obstruction. The value of paying attention to the kidneys and urinary tract in the course of bone scintigrams is stressed.

Bone and Bones↗
PubMed2002

Isolation and characterization of TgVP1, a type I vacuolar H+-translocating pyrophosphatase from Toxoplasma gondii. The dynamics of its subcellular localization and the cellular effects of a diphosphonate inhibitor.

Here we report the isolation and characterization of a type I vacuolar-type H(+)-pyrophosphatase (V-PPase), TgVP1, from an apicomplexan, Toxoplasma gondii, a parasitic protist that is particularly amenable to molecular and genetic manipulation. The 816-amino acid TgVP1 polypeptide is 50% sequence-identical (65% similar) to the prototypical type I V-PPase from Arabidopsis thaliana, AVP1, and contains all the sequence motifs characteristic of this pump category. Unlike AVP1 and other known type I enzymes, however, TgVP1 contains a 74-residue N-terminal extension encompassing a 42-residue N-terminal signal peptide sequence, sufficient for targeting proteins to the secretory pathway of T. gondii. Providing that the coding sequence for the entire N-terminal extension is omitted from the plasmid, transformation of Saccharomyces cerevisiae with plasmid-borne TgVP1 yields a stable and functional translation product that is competent in aminomethylenediphosphonate (AMDP)-inhibitable K(+)-activated pyrophosphate (PP(i)) hydrolysis and PP(i)-energized H(+) translocation. Immunofluorescence microscopy of both free and intracellular T. gondii tachyzoites using purified universal V-PPase polyclonal antibodies reveals a punctate apical distribution for the enzyme. Equivalent studies of the tachyzoites during host cell invasion, by contrast, disclose a transverse radial distribution in which the V-PPase is associated with a collar-like structure that migrates along the length of the parasite in synchrony with and in close apposition to the penetration furrow. Although treatment of T. gondii with AMDP concentrations as high as 100 microm had no discernible effect on the efficiency of host cell invasion and integration, concentrations commensurate with the I(50) for the inhibition of TgVP1 activity in vitro (0.9 microm) do inhibit cell division and elicit nuclear enlargement concomitant with the inflation and eventual disintegration of acidocalcisome-like vesicular structures. A dynamic association of TgVP1 with the host cell invasion apparatus is invoked, one in which the effects of inhibitory V-PPase substrate analogs are exerted after rather than during host cell invasion.

Amino Acid Sequence↗
PubMed1998

Influence of the phosphate balance on the activity distribution of 99mTc-hydroxy-methylene diphosphonate. Experimental studies in the mouse.

OBJECTIVE: The purpose was to determine whether changes in the phosphate balance have an influence on the distribution of bone-seeking radiopharmaceuticals. MATERIAL AND METHODS: The biodistribution of 99mTc-HDP in mice, intravenously administered under varying conditions, was assessed by removing different organs and estimating their activity in a scintillation counter. Some experiments were also performed with 99mTc-MDP and 99mTc-DPD. RESULTS: After 1 h and 18 h on phosphate-enriched drinking water, the mice showed a strongly increased uptake in all organs/tissues representing background activity and a decrease in the bone uptake. This pattern changed with time. After 6-8 days of phosphate load, we saw a more favourable distribution with a reduction of the background and whole-body activity. Administration of hPTH 1-34 gave rise to an activity distribution similar to that after 6-8 days on phosphate-enriched water. Changing the phosphate balance had less obvious effects on the distribution of 99mTc-MDP and 99mTc-DPD. CONCLUSION: The activity distribution of bone-seeking radiopharmaceuticals in the mouse is affected by the phosphate balance. The mechanism behind this finding is unknown but it may be partially mediated by PTH. It is possible that changes in the phosphate balance, induced by pharmaceuticals or by dietary changes, may affect the image quality at bone scintigraphy.

Animals↗