Search PubMed⌕ Search

Biomedical subjects

R R Recker

Publications and source records attributed to R R Recker.

At least 145 records · Page 8Linked to original sources
PubMed1985

The effect of milk supplements on calcium metabolism, bone metabolism and calcium balance.

Twenty-two healthy postmenopausal women were divided into two groups, one group of 13 received milk supplementation of 24 oz per day and the other group of 9 controls received no intervention during two years of observation. Extensive inpatient metabolic balance and radiocalcium kinetic studies were performed at the beginning and at the end of one year of observation. In the milk supplement group, fractional calcium absorption (x +/- SD) decreased from .243 +/- .058 to .176 +/- .058, absorbed calcium increased from .159 +/- .052 gm/d to .248 +/- .063 gm/d, urine calcium increased from .117 +/- .034 gm/d to .146 +/- .027 gm/d, bone accretion decreased from .385 +/- .079 gm/d to .326 +/- .063 gm/d, bone resorption decreased from .446 +/- .098 gm/d to .342 +/- .106 gm/d and endogenous fecal calcium increased from .105 +/- .023 gm/d to .120 +/- .021 gm/d. All these changes were significant within the group and the mean changes were significantly different from the mean changes observed in the control group. Calcium balance in the milk supplemented group improved from -.061 +/- .056 gm/d to -.017 gm/d +/- .073 gm/d. Predicted changes in calcium and bone metabolism held true except that the suppression of bone remodeling was less than previously found using calcium carbonate supplements. We conclude that milk and milk products can be recommended as sources of calcium, that data on the effects of increasing calcium intake from other sources can be applied to milk and that milk may offer an advantage because it does not suppress bone remodeling as severely as calcium carbonate.

Aged↗
PubMed1985

Bone disease in alcohol abuse.

We evaluated bone disease in eight white men between the ages of 49 and 61 years who had been abusing alcohol for at least 10 years. The mean density of vertebral cancellous bone was 58% of normal, whereas the mean density of appendicular cortical bone was 90% of normal. Marked reduction in active bone resorption and bone formation was seen without evidence of osteomalacia. Serum levels of calcium and magnesium were in the lower range of normal; serum levels of phosphorus, calcifediol, and calcitriol were normal; and serum levels of parathyroid hormone and nephrogenous cyclic adenosine monophosphate were in the higher range of normal. These data suggest that bone disease in these subjects is not due to inhibition of parathyroid hormone secretion or function, or abnormal vitamin D metabolism, but to an inhibition of bone remodeling by a mechanism independent of the calciotropic hormones.

Adult↗
PubMed1985

Estimation of true calcium absorption.

Measurements of true calcium absorption fraction in women were evaluated to see how closely calculations based on a single measurement of serum specific activity after administration of an oral calcium tracer might approximate the absorption value derived from the full, double-isotope absorption procedure. True absorption, body size, and miscible pool turnover could together explain better than 93% of the variance in serum calcium specific activity values 5 hours after a tracer-labeled test meal. Because measurement of pool turnover is not available routinely, it was dropped from the model, and a predictor equation was developed that allowed estimation of true absorption from the 5-hour serum specific activity value, height, and weight. These variables explained 90.8% of the variance in the 5-hour values and gave estimates of true absorption with a 95% confidence interval of +/- 0.055. This small range of uncertainty makes the procedure useful in estimating absorption efficiency for calcium therapy in routine clinical practice.

Administration, Oral↗
PubMed1984

Expansion of the medullary cavity at the expense of cortex in postmenopausal osteoporosis.

Transilial biopsies from postmenopausal osteoporotic patients showed that static features and remodeling activity tended to form a pattern, with the area midway between the cortices having less bone and lower remodeling activity than the area closer to the inner boundary of the cortex. The appearance, enlargement, and coalescence of the resorption cavities within the subendosteal area of the cortex lead to negative bone balance and a progressive trabeculation of the cortex, resulting in the formation of a transitional zone. Therefore, in most cases we can distinguish two different zones, transitional and trabecular zones, within the area usually known as the trabecular bone area. The transitional zone undergoes more active remodeling than the trabecular zone and has an important role in evaluation of the traditional trabecular bone volume and remodeling dynamics depending on the field selection for this evaluation, i.e., the proportion between transitional and trabecular zones within the selected fields. We postulate that the appearance of resorption cavities in the subendosteal area of the cortex depends on excessive osteoclast work, and bone loss in the resulting transitional zone depends on a combination of excessive osteoclast work and defective osteoblast work, with the osteoclast excessive work predominating.

Biopsy↗
PubMed1983

Osteoporosis.

Explore the source record for details and available documents.

Adult↗
PubMed1982

The label escape error: determination of the active bone-forming surface in histologic sections of bone measured by tetracycline double labels.

Twenty healthy female beagles, all postbreeding age, were given two bone-labeling agents. Transilial bone biopsies were obtained and embedded undecalcified. Double-labeled, single-labeled, and unlabeled surfaces were determined along with the interlabel width on unstained sections under fluorescent light. Mean osteon thickness was determined on toluidine blue-stained sections. A mathematical model for predicting the amount of singly labeled surface was tested and compared to the amount of surface actually found occupied by single labels of either color. We found that the model accurately predicted the amount of singly labeled surface and that the amount of singly labeled surface labeled by one agent was equal to that labeled by the other (r = 0.977, P less than .001). We conclude that singly labeled surfaces in these animals were so labeled because bone formation either began or ended in the interval between administration of the two labels and that the proposed model accurately predicts this quantity of singly labeled surface without the need to measure any singly labeled surface. This label escape phenomenon must be taken into account when measuring bone formation rates by tetracycline labeling, and the model should be used whenever it is suspected that single labels appear that are not due to label escape.

Animals↗
PubMed1982

Bone disease in primary biliary cirrhosis: histologic features and response to 25-hydroxyvitamin D.

Fifteen female patients with primary biliary cirrhosis were evaluated for vitamin D status and evidence of metabolic bone disease. Full-thickness iliac crest bone biopsy specimens with histomorphometric analysis after double tetracycline labeling were performed before and after 1 yr of treatment with oral 25-hydroxyvitamin D (100 micrograms/day). Initially, serum 25-hydroxyvitamin D levels were low (less than 15 ng/ml) in 11 of the 15 patients and were increased to normal (greater than 25 ng/ml) in all patients within 3 mo. Serum parathyroid hormone levels were low normal or not detectable in all patients and did not change with therapy. No patient had a fracture during the treatment. No evidence of osteomalacia was found initially or in follow-up study in any patient. Follow-up histomorphometric analysis at the end of the 1-yr treatment showed that bone volume decreased during the study interval despite therapy (p less than 0.001). Photon beam densitometry confirmed the loss in trabecular density of the radius over the study interval (p less than 0.03). The mean fractional osteoid surface was not increased initially and did not change with therapy. The mean linear bone appositional rate as measured by double tetracycline labeling was not decreased initially and did not change with therapy. It was concluded that in moderate to severe primary ciliary cirrhosis, initial 25-hydroxyvitamin D levels are low and are rapidly corrected by oral 25-hydroxyvitamin D. These patients have significant osteoporosis which progresses despite 25-hydroxyvitamin D.

25-Hydroxyvitamin D 2↗
PubMed1982

Effects of nitrogen, phosphorus, and caffeine on calcium balance in women.

The effects of different levels of nitrogen, phosphorus, and caffeine intake on calcium balance and on certain of its components were assessed in 170 studies in normal middle-aged, but still premenopausal women. Statistically significant negative associations with calcium balance were found for nitrogen and for caffeine, but no effect could be found for phosphorus. Higher nitrogen intakes were associated with proportionately higher levels of urinary calcium; higher phosphorus intake was associated with slightly lower levels of urinary calcium but also with slightly more intestinal secretion of calcium. Since these two effects were opposite in direction, there was no net association of different phosphorus intakes with calcium balance. Caffeine intake was associated with higher levels of both urinary calcium and intestinal calcium secretion. None of the three intake variables was associated with differences in calcium absorption efficiency. Both the nitrogen and the caffeine effects were proportional to intake. The magnitude of the effects observed was such that a 50% increase in intake of nitrogen above the group mean intake value would be predicted to result in calcium balance shift of -0.032 gm/day. For caffeine, the corresponding calcium balance shift would be predicted to be -0.006 gm/day.

Adult↗
PubMed1978

Menopausal changes in calcium balance performance.

Calcium balance as a function of both intake and absorption of calcium fromthe diet was measured 274 times in 168 normal perimenopausal women, and comparisons made between groups of women segregated according to menopausal and estrogen therapy status. As previously reported, there is a statistically significant positive correlation between calcium balance and both calcium intake and calcium absorption. In 207 studies in premenopausal women calcium balance averaged -0.0199 gm/day, whereas in 41 studies in postmenopausal women untreated with estrogen, calcium balance averaged -0.043 gm/day (p less than 0.02). The balance difference was due approximately equally to decreased absorption from the diet and to increased urinary excretion. Twenty-six estrogen-treated postmenopausal women exhibited balance performance indistinguishable from that of the premenopausal group. In 16 women who were studied twice, 5 years apart, and who went through menopause between studies, calcium balance shifted by -0.0307 gm/day (p less than 0.05) as compared with 72 women also studied twice, but without change in menstrual status, in whom mean balance did not change significantly. Calcium intake requirement for zero balance was calculated for both the estrogen-replete and estrogen-deprived groups. Premenopausal and treated postmenopausal women exhibited an intake requirement of 0.990 gm/day Ca, whereas the untreated postmenopausal women had an apparent requirement of 1.504 gm/day (p less than 0.01). We conclude that there is a specific, estrogen-related shift in calcium performance across menopause and that the reason for the positive effect of estrogen on balance and intake requirement is a combination of enhancement of intestinal absorption efficiency and improved renal calcium conservation.

Absorption↗
PubMed1978

Menopausal changes in bone remodeling.

Bone remodeling was measured by a calcium-kinetic method in 151 normal perimenopausal women, and the effect of estrogen status on remodeling level and skeletal balance was determined. Premenopausal women exhibited remodeling rates of 0.337 gm/day Ca for mineral accretion and 0.358 gm/day Ca for mineral resorption. The difference between the two rates (computed skeletal balance) was -0.021 gm/day Ca. Postmenopausal women treated with estrogen in a mean dose of 0.0188 mg equivalents of ethinyl estradiol exhibited values for accretion and resorption (0.332 and 0.351 gm/day Ca), essentially identical with those of the premenopausal group. However, untreated postmenopausal women exhibited remodeling rates of 0.387 gm/day Ca for accretion and 0.425 gm/day Ca for resorption, with a computed skeletal balance of -0.038 gm/day Ca. These values were significantly higher than those of either the premenopausal or treated postmenopausal groups. Paired studies across menopause in 15 of the women demonstrated a rise in remodeling rates virtually identical to that estimated from the differences between groups. Estrogen loss at menopause is thus associated with an apparent partial release from an inhibition of skeletal resorption, and this release is, in whole or part, responsible for the negative skeletal balance shift associated with the postmenopausal years.

Adult↗
PubMed1977

Calcium balance and calcium requirements in middle-aged women.

Calcium balance performance was evaluated in 130 normal perimenopausal women ages 35 to 50, studied on their usual, self-selected dietary calcium intakes. Two distinct balance methods were used, one based on customary intake and output measurements, and the other based on absorption and clearance of two simultaneously administered calcium isotopes. Both methods yielded essentially identical results. Under study conditions as closely approximating normal living as possible, these women averaged -24 and -31 mg Ca/day by the two balance methods (exclusive of unmeasured dermal losses). More significantly, there was a positive correlation between intake and balance, with women on higher self-selected intakes exhibiting more positive balance than women selecting lower intakes. The calcium intake predicted from our data which would be required to produce an average balance of zero was 1.241 g/day. This is significantly in excess of the current recommended dietary allowance for calcium. The implications and significance of this discrepancy are explored in detail.

Absorption↗
PubMed1977

Effect of estrogens and calcium carbonate on bone loss in postmenopausal women.

Sixty postmenopausal women were placed in three groups--control, sex hormone-treated, and CaCO3-treated--and followed for 2 years. Skeletal mass decreased by 1.18%/year in the control group, 0.15%/year in the hormone group, and 0.22%/year in the CaCO3 group by radiogrammetry; and 2.88%/year in the control group, 0.73%/year in the hormone group, and 1.83%/year in the CaCO3 group by photon absorptiometry. The treatment groups differed significantly from the control group except for photon absorptiometry in the CaCO3 group. Bone accretion and resorption decreased in the treatment groups as measured by calcium tracer kinetics, resorption more so than accretion. We conclude that [1] these techniques are sufficiently sensitive to detect age-related bone loss; [2] postmenopausal sex-hormone replacement measurably decreases age-related bone loss by suppressing bone turnover, resorption more than accretion; and [3] calcium supplements produce the same effect but at the dose we used were slightly less effective.

Absorptiometry, Photon↗
PubMed1977

Evidence of aluminum absorption from the gastrointestinal tract and bone deposition by aluminum carbonate ingestion with normal renal function.

The question of whether aluminum is toxic in patients ingesting large oral loads, either for phosphate binding in renal dialysis or as an antacid for peptic ulcer, has been raised. The permeability of the gut barrier for aluminum has not been established because of the lack of precise analytical techniques. Urine aluminum was measured in this study before and during oral aluminum carbonate loading in six subjects with normal renal function, one of which had peptic ulcer disease and a 25-year history of high oral aluminum ingestion. The analytical procedure involved destructive neutron activation analysis. Aluminum was present in the urine in all instances before loading and rose in every case from 4-fold to 10-fold. Bone aluminum was measured in six autopsy specimens, three dialysis patients, three nondialysis patients, and in an iliac crest biopsy from the peptic ulcer patient who had osteoporosis. The bone biopsy aluminum level in the ulcer patient was intermediate between those of "normal subjects" and patients on dialysis. These results show that the gut barrier is permeable to heavy aluminum load and suggest that bone aluminum deposition occurs in humans with normal renal function.

Adult↗
PubMed1975

Effect of hydrochlorothiazide on phosphorus during treatment with diphosphonate.

The effects of probenecid and hydrochlorothiazide on renal handling of phosphorus during hyperphosphatemia induced by diphosphonate (ethane-1-hydroxy-1, 1-diphosphonate, EHDP) was studied. Measurements of calcium, phosphorus, and creatinine clearance were performed in 2 sessions on each of 3 consecutive days in 10 normal fasting volunteers during the morning hours from 8 A.M. to 12 noon. During 2 to 3 wk thereafter, each subject was treated with EHDP, 30 mg/kg/day. The second group of studies were performed in the same manner as the first except the EHDP administration was continued throughout. EHDP caused elevation of serum phosphorus in all cases. Probenecid did not affect urine phosphorus. Hydrochlorothiazide caused a transient phosphaturia of similar magnitude in the EHDP treated and untreated states. Creatinine clearance was not affected by any of the treatments and urine calcium was decreased by EHDP. It was concluded that hydrochlorothiazide inhibits tubular reabsorption of phosphorus but that it does not affect the mechanism whereby EHDP causes increased tubular reabsorption of phosphorus. Chronic administration of hydrochlorothiazide along with EHDP may inhibit hyperphosphatemia and may change the bone effects of EHDP.

Adult↗