demeclocycline and Osteoporosis

We measured the individual lengths of fluorescent labels on the three subdivisions of the endosteal envelope in iliac bone biopsy specimens produced by the administration of both oxytetracycline and demethylchlortetracycline. Fifty-one healthy subjects and 53 patients with postmenopausal osteoporosis were labeled in the stated order, and 8 osteopenic patients were labeled in the reverse order. Whatever the order of administration, the demethylchlortetracycline label was longer than the oxytetracycline label. We conclude: (1) the difference in label lengths reflects a difference between the two compounds in some intrinsic property, whether physical, chemical, or pharmacokinetic. (2) If the calculation of extent of mineralizing surface is based on the mean length of the two labels, a suitable correction should be applied to the shorter label; alternatively, the length of the longer label alone should be used. (3) Unlabeled osteoid not due to label escape probably results from slow terminal mineralization after cessation of matrix synthesis during which too few tetracycline molecules are incorporated to exceed the threshold for visible fluorescence, rather than from the temporary interruption of mineralization followed by its resumption.

Topics: Adult; Aged; Bone and Bones; Bone Density; Demeclocycline; Female; Fluorescent Dyes; Humans; Microscopy, Fluorescence; Middle Aged; Minerals; Osteogenesis; Osteoporosis; Oxytetracycline

Thirty-four normal Caucasian women and 69 patients with osteoporosis were given two bone-labeling agents. Transilial biopsies were obtained and embedded undecalcified. Fractional surfaces covered by double label and single label were determined, along with total surface and double label width by fluorescent microscopy. Mean wall thickness was measured on toluidine blue-stained sections. The mathematical model for predicting the amount of single-labeled surface was compared to the actual amount of surface covered by single label. We found an excess of single labels compared to the model in both groups, more so in the normals, and suggest the explanation is that bone-formation pauses at formation sites in both groups but tends not to resume in the patients. This results in a shortened functional life span of the osteoblast and bone loss. Further, the data suggest that for accurate expression of bone formation rates in trabecular bone using a volume referent, one should use the whole bone tissue including bone and marrow and should express the bone-forming surface as the double-labeled surface plus one-half the measured single-labeled surface.

Topics: Aged; Biopsy, Needle; Bone and Bones; Demeclocycline; Female; Humans; Middle Aged; Models, Biological; Osteoporosis; Tetracycline

The acute effects of immobilization on cortical and trabecular bone formation were studied in juvenile male rhesus monkeys (Macaca mulatta). Four animals were immobilized for two weeks by application of total body casts. Two control monkeys were housed in separate metabolic cages under similar environmental and dietary conditions. Tetracycline derivatives were administered on three separate occasions to label sites of bone formation. The tetracycline-labeling frequency and mineral apposition rate of osteons and trabecular bone surfaces in the humerus and femur were determined. The inhibition of bone formation induced by immobilization was more pronounced in trabecular bone. Immobilized monkeys exhibited a moderate, but statistically nonsignificant, reduction in the percentage of osteons forming bone. Conversely, the dramatic decline in the percentage of trabecular surfaces undergoing bone formation in immobilized monkeys was found to be highly significant. The diminished rate of mineral apposition in osteons suggested that osteoblastic activity was impaired in cortical bone during immobilization. The mineral apposition rate in trabecular bone could not be determined reliably due to minimal tetracycline deposition, which indicated that osteoblastic activity and/or recruitment almost ceased in the metaphyseal tissue of immobilized monkeys.

Topics: Animals; Bone and Bones; Bone Regeneration; Bone Resorption; Demeclocycline; Femur; Humerus; Immobilization; Macaca mulatta; Male; Minerals; Osteoblasts; Osteoporosis; Oxytetracycline; Tetracycline

Studies of flexible plates made of plastic have shown that less osteoporosis develops beneath them than beneath rigid metal plates. However, to date plastic plates of appropriate physical properties and biocompatibility are not available for use in humans. To determine if a similar beneficial effect could be obtained using metal plates, the effects of thick chromium cobalt plates were contrasted in experiments in dogs with the effects of thinner plates of similar design made of titanium, 6-aluminum, 4-vandium. A significant reduction in the osteoporosis was obtained by use of the more flexible plates. Following plate application a delayed, massive, transient stimulus to bone formation occurred endosteally, periosteally, and intracortically. Despite this, a substantial decrease in bone mass occurred, primarily mediated by endosteal bone resorption. Intracortical porosity played little or no role in net bone loss. The major effects subsided by six months. Recovery after plate removal was predominantly the result of endosteal new-bone formation.

Topics: Aluminum; Animals; Biocompatible Materials; Bone Development; Bone Plates; Bone Resorption; Chromium Alloys; Demeclocycline; Dogs; Doxycycline; Elasticity; Evaluation Studies as Topic; Femur; Male; Methacycline; Osteoporosis; Titanium; Vanadium

Topics: Adult; Aged; Bone Diseases; Calcium; Calcium Isotopes; Calcium Metabolism Disorders; Child, Preschool; Demeclocycline; Diet Therapy; Dietary Proteins; Female; Glutens; Humans; Hydrochlorothiazide; Infant; Kinetics; Male; Methandrostenolone; Middle Aged; Osteoporosis; Rickets; Tetracycline; Vitamin D

Topics: Blindness; Cathartics; Chlordiazepoxide; Corneal Ulcer; Cushing Syndrome; Demeclocycline; Drug Therapy; Eye Manifestations; Glycosuria; Humans; Keratoconjunctivitis; Osteoporosis; Phenacetin; Phenolphthaleins; Pyelonephritis; Stevens-Johnson Syndrome; Toxicology; Triamcinolone