Ascertainment of risk factors for osteoporosis: comparison of interview data with medical record review.

To determine the accuracy of self-reported risk factors for osteoporosis, an age-stratified random sample of Rochester, MN, women was studied. Results from a structured face-to-face interview were compared with information documented in contemporary inpatient and outpatient health care records in the community. Using the kappa statistic to evaluate concordance of these two data sources, we found substantial agreement for a history of proximal femoral and distal forearm fractures, peptic ulcer disease, estrogen replacement therapy and oral contraceptive use, and cigarette and alcohol exposure.

Effect of age on variables relating to calcium and phosphorus metabolism in women.

Lack of adequate data concerning the effect of age on biochemical variables relating to bone and mineral metabolism hampers research on age-related bone loss in women. Furthermore, to detect disease and to monitor therapy, clinical laboratories require reference values derived from an appropriate population sample. Therefore, we determined the age-specific distribution of values for serum concentrations of calcium, inorganic phosphorus, alkaline phosphatase, bone Gla protein, and parathyroid hormone; for creatinine clearance; for fasting urinary calcium:creatinine ratio; and for 24 h urinary excretion of calcium, hydroxyproline, and cyclic AMP in a population-based sample of 301 white women.

Cancellous bone remodeling in type I (postmenopausal) osteoporosis: quantitative assessment of rates of formation, resorption, and bone loss at tissue and cellular levels.

The cellular mechanisms for bone loss in type I (postmenopausal) osteoporosis are highly controversial. We attempted to resolve this by assessing rates of formation and resorption of iliac cancellous bone by a new histomorphometric method in 89 women with osteoporosis (mean age +/- SD, 66 +/- 6 years) and in 32 carefully selected normal postmenopausal women (64 +/- 6 years). In the osteoporotic women, bone resorption rate was increased by 39% (P less than 0.

Effect of fluoride treatment on the fracture rate in postmenopausal women with osteoporosis.

Although fluoride increases bone mass, the newly formed bone may have reduced strength. To assess the effect of fluoride treatment on the fracture rate in osteoporosis, we conducted a four-year prospective clinical trial in 202 postmenopausal women with osteoporosis and vertebral fractures who were randomly assigned to receive sodium fluoride (75 mg per day) or placebo. All received a calcium supplement (1500 mg per day).

Biochemistry of protein-isocyanate interactions: a comparison of the effects of aryl vs. alkyl isocyanates.

In addition to their use in the polyurethane and pesticide industries, isocyanates have proven to be useful probes for the exploration of protein structure. This paper focuses on three aspects of isocyanates: their broad reactivity, their reversible interaction with cholinesterases, and the relative hydrolysis rates of alkyl and aryl isocyanates. The broad reactivity of isocyanates as well as the demonstrated affinity labeling of serine and sulfhydryl esterases are discussed.

A high-resolution 1H-NMR investigation of the histidine-binding protein J of Salmonella typhimurium. Substrate-induced conformational changes.

High-resolution 1H-NMR spectroscopy at 600 MHz has been used to investigate the conformational transitions of the histidine-binding protein J of Salmonella typhimurium in solution as a function of pH and of L-histidine concentration. The dissociation constant for the binding of L-histidine to histidine-binding protein J increases from 6.0 X 10(-8) to 5.

Proton nuclear magnetic resonance studies of isonitrile-heme protein complexes.

Steric interactions between bound ligand molecules and the valine E11 methyl groups of human hemoglobin and sperm whale myoglobin have been examined directly by high resolution NMR techniques. The methyl proton resonances of this amino acid are shifted markedly upfield and away from the bulk of the protein resonances by the shielding effect of circulating pi electrons in the porphyrin ring. We have monitored the valine resonance in the presence of CO and a series of isonitriles and found considerable shifts in its position, both between the various protein complexes and among the different liganded states.

Phytochrome induces photoreversible calcium fluxes in a purified mitochondrial fraction from oats.

Previous studies have indicated that phytochrome regulates Ca(2+) fluxes across the plasma membrane of plant cells. In this study we investigated whether phytochrome can also regulate such fluxes across mitochondrial membranes, using the Ca(2+)-sensitive dye murexide to monitor the uptake and release of Ca(2+) by mitochondria. The results showed that Ca(2+) fluxes in these organelles could be photoreversibly altered, red light diminishing the net uptake rate and far-red light restoring this rate to its dark control level.

Modulation of a mitochondrial function by oat phytochrome in vitro.

Previous data in the literature have indicated that phytochrome could alter the rate of reduction of exogenously added NADP by a pea mitochondrial preparation in vitro. These results could not be duplicated using a mitochondrial preparation isolated from etiolated oat seedlings. Further experimentation demonstrated that the addition of Pr to the preparation, in combination with a far red light illumination, could significantly reduce the rate of oxidation of NADH by the external dehydrogenases of oat mitochondria.

Further characterization of the in vitro binding of phytochrome to a membrane fraction enriched for mitochondria.

This study employs (125)I-labeled phytochrome ((125)I-P) from oats to quantitate the binding of phytochrome to a membrane fraction from oats that is highly enriched for mitochondria, and it examines several parameters that influence this attachment. The binding of (125)I-Pfr to the mitochondrial fraction of unirradiated oat seedlings is significantly higher than that of (125)I-Pr. However, (125)I-Pfr and (125)I-Pr bind in equal quantities to mitochondrial preparations isolated from light-exposed seedlings.

Use of I-labeled phytochrome to quantitate phytochrome binding to membranes of Avena sativa.

Purified oat phytochrome was labeled with (125)I without altering the photoreversibility or absorbance properties of the pigment. The radiolabeled phytochrome was used in experiments in vitro to quantitate the binding of the pigment to both crude and purified membrane preparations from oat tissue. After the membranes were allowed to react with (125)I-labeled phytochrome, washed free of unbound material, and pelleted, they were found to have significant levels of radioactivity bound to them.