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PubMed2007

Differences in 24-hour urine composition between black and white women.

Black women are less likely to develop kidney stones and have greater bone mass than white women. However, little is known about racial differences in urine composition. Urine pH, volume, and 24-h urinary excretion of calcium, citrate, oxalate, uric acid, sodium, potassium, magnesium, phosphate, sulfate, and creatinine of 146 black women were compared with 330 white women in the Nurses' Health Study. All participants were postmenopausal non-stone formers. ANOVA was used to compare mean urinary values. Linear regression models were adjusted for age, body mass index, dietary intake, and urinary factors. On average, black women excreted 65 mg less urinary calcium (P < 0.001), 4 mg more oxalate (P < 0.001), 9 mEq less potassium (P < 0.001), 11 mg less magnesium (P = 0.003), 120 mg less phosphate (P < 0.001), and 3 mmol less sulfate (P < 0.001) per day than did white women. The urine pH of black women was 0.11 units higher (P = 0.03) and urine volume was 0.24 L less (P = 0.001). The urinary relative supersaturations of calcium oxalate (P = 0.03) and brushite (P = 0.002) were lower in black women. No other significant differences were observed. Differences in urinary calcium and pH persisted after multivariate adjustment and after exclusion of participants who were taking thiazide diuretics or those with diabetes. In conclusion, black women excrete less urinary calcium and have a higher urinary pH than do white women. These differences are not explained by differences in age, body mass index, or diet and may account for the lower incidence of both nephrolithiasis and osteoporosis in black women.

Aged↗
PubMed1994

Spinal bone loss in postmenopausal women supplemented with calcium and trace minerals.

The effects of calcium supplementation (as calcium citrate malate, 1000 mg elemental Ca/d) with and without the addition of zinc (15.0 mg/d), manganese (5.0 mg/d) and copper (2.5 mg/d) on spinal bone loss (L2-L4 vertebrae) was evaluated in healthy older postmenopausal women (n = 59, mean age 66 y) in a 2-y, double-blind, placebo-controlled trial. Changes (mean +/- SEM) in bone density were -3.53 +/- 1.24% (placebo), -1.89 +/- 1.40% (trace minerals only), -1.25 +/- 1.46% (calcium only) and 1.48 +/- 1.40% (calcium plus trace minerals). Bone loss relative to base-line value was significant (P = 0.0061) in the placebo group but not in the groups receiving trace minerals alone, calcium alone, or calcium plus trace minerals. The only significant group difference occurred between the placebo group and the group receiving calcium plus trace minerals (P = 0.0099). These data suggest that bone loss in calcium-supplemented, older postmenopausal women can be further arrested by concomitant increases in trace mineral intake.

Aged↗
PubMed2004

Kidney stone inhibitors in patients with renal stones and endemic renal tubular acidosis in northeast Thailand.

Distal renal tubular acidosis (dRTA) is generally associated with hypercalciuria, hypocitraturia, and nephrolithiasis. Our intention was to study glycosaminoglycans (GAGS) and nephrocalcin (NC), two well-known crystal growth inhibitors, in a population with endemic dRTA and nephrolithiasis in northeast (NE) Thailand. We studied 13 patients, six with dRTA and seven with nephrolithiasis with normal or undefined acidification function. Six healthy adults living in the same area as the patients and another six from the Bangkok (BKK) area were used as controls. We measured urinary pH, ammonia, calcium, citrate, magnesium, oxalate, potassium, sodium and uric acid. GAGS were determined by an Alcian blue precipitation method and were qualitated by agarose gel electrophoresis after being isolated using 5% cetyltrimethylammonium bromide at pH 6.0. NC isoforms were isolated as previously described by Nakagawa et al. Citrate was higher in BKK controls ( p<0.04). There was a striking difference among GAGS from BKK when compared with other groups (103.85+/-10.70 vs. 23.52+/-8.11 for dRTA, 22.36+/-14.98 for kidney stone patients and 14.73+/-2.87 mg/ml in controls from the NE region, ( p<0.0001). dRTA and stone-forming patients excrete proportionally more (C+D) than (A+B) NC isoforms ( p<0.05). Also, their NC showed a 100-fold weaker binding capacity of calcium oxalate monohydrate crystals. The ratio of chondroitin sulfate/heparin sulfate in GAGS was approximately 9/1. In addition to the traditional risk factors for nephrolithiasis in dRTA, GAGS and NC might play an important role in the pathogenesis of stone formation in this population.

Acidosis, Renal Tubular↗
PubMed2004

Infrequency of colonization with Oxalobacter formigenes in inflammatory bowel disease: possible role in renal stone formation.

BACKGROUND AND AIM: Calcium oxalate renal stones (RS) and hyperoxaluria are common in patients with inflammatory bowel disease (IBD). The absence of intestinal oxalate degrading bacteria, Oxalobacter formigenes, may cause hyperoxaluria in IBD. The aim of the present study was to examine: (i) the colonization of O. formigenes in patients with IBD and controls and to correlate its presence with urinary oxalate excretion; and (ii) urinary analytes contributing to RS in IBD. METHODS: Stool samples were studied for O. formigenes using polymerase chain reaction and Southern blotting in patients with IBD (n = 48: ulcerative colitis, 37; Crohn's disease, 11), RS (n = 87) and healthy subjects that were used as controls (n = 48). Levels of urinary oxalate, citrate, calcium, magnesium, creatinine and uric acid were estimated spectrophotometrically in each patient and in 13 controls for 24 h. RESULTS: Five of the 48 (10.4%) patients with IBD had RS. Five of the 48 (10.4%) patients with IBD, 25 of the 87 (29%) with RS and 27 of the 48 (56%) controls were colonized with O. formigenes (P < 0.001 for RS vs controls and P = 0.01 for RS vs IBD). Patients without O. formigenes had higher urinary oxalate than those with it (IBD, median 0.48 [range 0.11-2.09]vs 0.43 [range 0.16-1.10] mmol/24 h, P = NS; RS, median 0.59 mmol/24 h, range 0.14-1.90 vs 0.44 mmol/24 h, range 0.23-0.97; P = 0.008, Mann-Whitney U-test). Median excretion of oxalate was higher in IBD and RS than in controls (0.47 [0.11-2.09], 0.56 [0.14-1.9] and 0.41 [0.21-0.62] mmol/24 h; P < 0.01), respectively. Median calcium was also higher in IBD and RS than in controls (6.50 [1.38-21.00], 6.78 [1.55-20.30] and 4.99 [1.47-9.60] mmol/24 h; P < 0.05, Kruskal-Wallis H-test), respectively. Median urinary magnesium was higher in IBD than in RS and controls (4.57 [1.50-12.30], 3.60 [0.90-6.35] and 2.49 [0.74-4.80]; P < 0.001, Kruskal-Wallis H-test), respectively. Urinary citrate excretion was comparable in IBD, RS and controls. CONCLUSIONS: Patients with IBD and RS rarely have O. formigenes in their stools as compared with controls; this may contribute to hyperoxaluria in IBD. Hyperoxaluria and hypercalciuria may contribute to RS in patients with IBD. Hypermagnesuria in patients with IBD may protect them from RS.

Adolescent↗
PubMed1992

Calcium supplementation and increases in bone mineral density in children.

BACKGROUND: Increased dietary intake of calcium during childhood, usually as calcium in milk, is associated with increased bone mass in adulthood; the increase in mass is important in modifying the later risk of fracture. Whether the increase is due to the calcium content of milk, however, is not certain. METHODS: We conducted a three-year, double-blind, placebo-controlled trial of the effect of calcium supplementation (1000 mg of calcium citrate malate per day) on bone mineral density in 70 pairs of identical twins (mean [+/- SD] age, 10 +/- 2 years; range, 6 to 14). In each pair, one twin served as a control for the other; 45 pairs completed the study. Bone mineral density was measured by photon absorptiometry at two sites in the radius (at base line, six months, and one, two, and three years) and at three sites in the hip and in the spine (at base line and three years). RESULTS: The mean daily calcium intake of the twins given placebo was 908 mg, and that of the twins given calcium supplements was 1612 mg (894 mg from the diet and 718 mg from the supplement). Among the 22 twin pairs who were prepubertal throughout the study, the twins given supplements had significantly greater increases in bone mineral density at both radial sites (mean difference in the increase in bone mineral density: midshaft radius, 5.1 percent [95 percent confidence interval, 1.5 to 8.7 percent]; distal radius, 3.8 percent [95 percent confidence interval, 1.4 to 6.2 percent]) and in the lumbar spine (increase, 2.8 percent [95 percent confidence interval, 1.1 to 4.5 percent]) after three years; the differences in the increases at two of three femoral sites approached significance (Ward's triangle in the femoral neck, 2.9 percent; greater trochanter, 3.5 percent). Among the 23 pairs who went through puberty or were postpubertal, the twins given supplements received no benefit. CONCLUSIONS: In prepubertal children whose average dietary intake of calcium approximated the recommended dietary allowance, calcium supplementation increased the rate of increase in bone mineral density. If the gain persists, peak bone density should be increased and the risk of fracture reduced.

Absorptiometry, Photon↗
PubMed2000

The effects of age and gender on parathyroid hormone dynamics.

BACKGROUND AND AIMS: Hyperparathyroidism is a risk factor for bone loss. An age-related increase in parathyroid hormone (PTH) level has been demonstrated in several studies. It has been suggested that the type II osteoporotic syndrome, a condition of increased prevalence among elderly women, may be at least partially caused by elevations in intact parathyroid hormone (iPTH) levels. To date, however, the effects of age and gender per se on PTH dynamics in healthy subjects independent of other risk factors such as vitamin D deficiency and/or impaired renal function that can impact on parathyroid function, remain unknown. In this study, we used citrate and calcium (Ca) infusions to characterize the impact of age and gender on PTH dynamics in normal subjects. SUBJECTS AND METHODS: Twelve young women with mean age +/- SD of 26.4 +/- 1.6 years, 12 young men with mean age of 26.6 +/- 1.3 years, 12 older women with mean age of 68.6 +/- 1.3 years and 12 older men with mean age of 67.2 +/- 1.6 years were studied. The sigmoidal curves relating serum iPTH to serum levels of ionized Ca (Cai) were characterized by maximal and minimal iPTH levels, the set-points (levels of Cai causing half-maximal suppression of iPTH), and the slopes of the curves at the set-points. RESULTS: Baseline serum Ca, Cai, 25 hydroxyvitamin D [25(OH)D] and 1,25 dihydroxyvitamin D [1,25(OH)2D3] levels, as well as the set-points, slopes and minimal values of the sigmoidal curves relating Cai to iPTH, did not differ among the four groups. iPTH levels at baseline were slightly but not significantly higher in the older age groups (P = 0.18). The maximal iPTH level was 25% higher in the older women than in the younger women, although this difference was not significant (P = 0.29). However, the integrated iPTH responses calculated from the areas under the curves (AUC) of iPTH levels vs. time during the calcium and citrate infusions were significantly higher in postmenopausal women than in young women during both infusions and in older men than in young men during the calcium infusion. There was no effect of gender on serum iPTH levels. CONCLUSIONS: In both women and men, ageing per se, independent of changes in vitamin D economy or renal function, is associated with an increase in integrated PTH secretory response to changes in serum calcium. No alterations in the Cai/iPTH set-point were present. The biological relevance of these modest increments in integrated iPTH levels during dynamic testing in older healthy men and women remain uncertain.

Adult↗
PubMed2002

Selenium intakes, absorption, retention, and status in adolescent girls.

OBJECTIVES: To assess selenium intakes, absorption, retention, and status in healthy adolescent girls and the effect of calcium supplementation on selenium parameters. DESIGN: Annual 2-week study conducted each year for 3 consecutive years in which yearly selenium intakes, absorption, and retention and blood selenium status were measured. SETTING: A metabolic unit in a large metropolitan hospital located in Columbus, Ohio--a low selenium region of the United States. SUBJECTS: Healthy white girls aged 11 to 14 years (n=16) enrolled in a calcium balance study and randomly assigned to receive a placebo of methylcellulose (n=9) or a calcium supplement containing 1,000 mg supplemental calcium as calcium citrate malate (n=7). INTERVENTIONS: Each subject consumed a diet with approximately 100 microg selenium/day during the yearly 2-week balance studies. RESULTS: Selenium status measurements (serum and erythrocyte selenium and glutathione peroxidase activity) were all within normal ranges for adults during the study. Apparent selenium absorption averaged 71%, 76%, and 74% for years 1, 2, and 3 of the study, respectively, and did not vary significantly (P>.05). Average daily selenium retention did not differ among the years of the study (P>.05) and indicated that the usual selenium intake was approximately 100 microg daily. Measurements of selenium status and retention did not differ between calcium-supplemented and placebo groups. CONCLUSIONS: An intake of approximately 100 microg selenium/day is the typical intake of the mineral among the subjects and appeared adequate to maintain selenium status in these healthy adolescent girls; in addition, calcium supplementation of 1,000 mg daily does not have a negative impact on selenium parameters.

Adolescent↗
PubMed1990

Effect of intermittent therapy with a slow-release fluoride preparation.

Long-term clinical effects of intermittent sodium fluoride (slow-release) therapy were assessed in 71 patients with primary osteoporosis. In Group I (receiving 1,25-(OH)2D3 2 micrograms/day for 2 weeks before 3 months of sodium fluoride treatment 25 mg twice a day, in each 5-month cycle), vertebral (L2-L4) bone mineral content did not change significantly. However, the L2-L4 bone mineral content significantly increased by 3.1% in Group II (those who did not receive 1,25-(OH)2D3 during 5-month cycle), 3.5% per patient year in Group III (combined NaF 25 mg twice a day with 1,25-(OH)2D3 0.5 micrograms/day for 12 months in each 13-month cycle), and by 7.8% per patient year in Group IV (combined NaF with calcium citrate for 12 months in each 13-month cycle). The rise in vertebral bone mineral content was sustained, with an annual increment of 4.2% during the third year compared with 4.4% during the first year. The vertebral fracture rate declined significantly from the pretreatment value in all groups, but comparison with a placebo control group was not available. There was no significant change in the bone density of the radial shaft or of the proximal femur. The rate of hip fracture (nontraumatic) during treatment was 1.8% per patient year, the same as before treatment. The drug was well tolerated with only minor infrequent gastrointestinal and rheumatic side effects. Thus, intermittent slow-release sodium fluoride treatment with adequate calcium supplementation augments spinal bone mass and apparently inhibits vertebral fractures, with a satisfactory safety of usage; however, it has no effect on appendicular bone mass or on hip fracture rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Density↗
PubMed2000

High sodium chloride intake is associated with low bone density in calcium stone-forming patients.

BACKGROUND: Although renal stone disease has been associated with reduced bone mass, the impact of nutrient intake on bone loss is unknown. SUBJECTS AND METHODS: The present study was undertaken to investigate the influence of nutrient intake on bone density of 85 calcium stone-forming (CSF) patients (47 male and 38 premenopausal females) aged 41+/-11 years (X+/-SD). Bone mineral density (BMD) was measured using dual energy X-ray absorptiometry at the lumbar spine (L2-L4) and femoral neck sites, and low BMD was defined as a T score < -1 (WHO criteria). A 4-day dietary record and a 24-hour urine sample were obtained from each patient for the assessment of nutrient intake and urinary calcium (U(Ca)), sodium (U(Na)), phosphate and creatinine excretion. RESULTS: Forty-eight patients (56%) presented normal BMD and 37 (44%) low BMD. There were no statistical differences regarding age, weight, height, body mass index, protein, calcium and phosphorus intakes between both groups. The mean U(Ca), phosphorus and nitrogen appearance also did not differ between groups. However, there was a higher percentage of hypercalciuria among low vs normal BMD patients (62 vs 33%, p < 0.05). Low BMD patients presented a higher mean sodium chloride (NaCl) intake and excretion (UNa) than normal BMD (14+/-5 vs 12+/-4 g/day and 246+/-85 vs 204+/-68 mEq/day, respectively p < 0.05). The percentage of patients presenting NaCl intake > or = 16 g/day was also higher among low vs normal BMD patients (35 vs 12%, p < 0.05). After adjustment for calcium and protein intakes, age, weight, body mass index, urinary calcium, citrate and uric acid excretion, and duration of stone disease, multiple-regression analysis showed that a high NaCl intake (> or = 16 g/day) was the single variable that was predictive of risk of low bone density in CSF patients (odds ratio = 3.8). CONCLUSION: These data suggest that reducing salt intake should be recommended for CSF patients presenting hypercalciuria and osteopenia.

Absorptiometry, Photon↗
PubMed2002

Risk of calcium oxalate nephrolithiasis in postmenopausal women supplemented with calcium or combined calcium and estrogen.

BACKGROUND: Recent studies showed that postmenopausal women lost less bone mass when supplemented with calcium or estrogen therapy. However, the safety of the treatments in terms of the risk of calcium oxalate stone formation is unknown. We therefore conducted this study to determine the alteration in calcium oxalate supersaturation after calcium supplement or after combined calcium and estrogen therapy in postmenopausal osteoporotic women. METHODS: Fifty-six postmenopausal women were enrolled in this study. All subjects were more than 10 years postmenopausal with vertebral or femoral osteoporosis by bone mineral density criteria. They were randomly allocated to receive either 625 mg of calcium carbonate (250 mg of elemental calcium) at the end of a meal three times a day (group A, n=26) or calcium carbonate in the same manner plus 0.625 mg/day of conjugated equine estrogen and 5 mg medrogestone acetate from day 1-12 each month (group B, n=30). The age (mean +/- S.E.M.) was 66.3 +/- 1.2 and 65.1 +/- 1.1 years, weight 54.1 +/- 1.2 and 55.3 +/- 2.1 kg, in group A and group B, respectively. Urine specimens (24-h) were collected at baseline and 3 months after treatment for the determination of calcium oxalate saturation by using Tiselius's index (AP(CaOx)) and calcium/citrate ratio. RESULTS: After 3 months of treatment, there was no significant alteration from baseline for urinary excretion of calcium, citrate and oxalate. Urinary phosphate excretion was significantly reduced (6.3 +/- 0.7 vs. 5.1 +/- 0.7 mmol/day for group A and 8.2 +/- 0.9 vs. 5.8 +/- 0.7 mmol/day for group B, P<0.05), whereas net alkaline absorption was significantly elevated (10.1 +/- 3.6 vs. 20.1 +/- 4.4 meq/day for group A and 4.8 +/- 3.2 vs. 19.9 +/- 3.6 meq/day for group B, P<0.05). Calcium/citrate ratio and AP(CaOx) determined at baseline were not different from the corresponding values after treatment in both groups; calcium/citrate: 10.1 +/- 3.1 vs. 10.1 +/- 2.5 for group A and 9.3 +/- 1.8 vs. 11.9 +/- 2.5 for group B and AP(CaOx): 1.1 +/- 0.1 vs. 1.3 +/- 0.2 for group A and 1.2 +/- 0.2 vs. 1.1 +/- 0.1 for group B. There were eight and nine patients with high AP(CaOx), or >2, at baseline and after treatment, respectively. CONCLUSIONS: Calcium supplement with a meal or combined calcium supplement and estrogen therapy is not associated with a significant increased risk of calcium oxalate stone formation in the majority of postmenopausal osteoporotic patients. Determination of urinary saturation for calcium oxalate after calcium and estrogen supplements, especially at the initial phase of treatment, may be helpful in the avoidance of nephrolithiasis.

Aged↗
PubMed1993

Bioavailability and pharmacokinetics of fluoride from two glutamine monofluorophosphate preparations.

A two-way cross-over study was conducted on 12 Caucasian male healthy volunteers aged between 25 and 38 years in order to determine the bioavailability and pharmacokinetics of fluoride after single oral administration in fasting conditions of two products (tablets and powder for oral use) of L-glutamine monofluorophosphate (G-MFP, CAS 116420-36-1). The two products contained the equivalent of 10 mg F and the equivalent of 300 mg CA as calcium gluconate and calcium citrate. The two products were found bioequivalent with regard to the release of fluoride, both on the basis of the AUC and Cmax of fluoride in plasma and of the urinary excretion of fluoride during the 48 h following the administration. The pharmacokinetics of fluoride in plasma is characterized by a short lag time (< 6 min), a rapid absorption, a peak which is reached 0.5-1.0 h after administration, followed by a biphasic elimination. The first phase with a k alpha of 1.8 h-1 is followed by a slower phase with a K beta of 0.14 h-1. Probably the terminal elimination rate is slower, about 0.05 h-1. The urinary excretion of fluoride during the 48 h after administration accounted for 40-50% of the administered dose of fluoride. The results are consistent with those found in previous studies after administration in fasting conditions of sodium fluoride or sodium monofluorophosphate alone or in combination with calcium salts.

Adult↗
PubMed2003

Therapy of osteoporosis in patients with Crohn's disease: a randomized study comparing sodium fluoride and ibandronate.

BACKGROUND: Osteoporosis is a frequent complication in Crohn's disease. Although the efficacy of both sodium fluoride and aminobisphosphonates in postmenopausal osteoporosis has been investigated in long-term therapy studies, no long-term results are available regarding the effect of these agents in the management of osteoporosis in patients with Crohn's disease. METHODS: Eighty-four patients with Crohn's disease and pathological bone mineral density findings were randomized to receive either vitamin D3 (1000 IU) and calcium citrate (800 mg) daily (group A) or sodium fluoride (25 mg b.d., group B) or intravenous ibandronate (1 mg every 3 months, group C) in addition to daily calcium/vitamin D substitution. On admission to the study and after 12 and 27 months, patients underwent dual-energy X-ray absorptiometry and radiological examination of the spine. RESULTS: Sixty-eight patients completed the 1-year observation period and were available for the intention-to-treat analysis. No new vertebral fractures were diagnosed. In group A, lumbar bone density increased by 2.6% (P = 0.066, N.S.), in group B by 5.7% (P = 0.003) and in group C by 5.4% (P = 0.003). Therapy with sodium fluoride was associated with an increase in osteocalcin (N.S.), whereas administration of ibandronate was associated with a decrease in the resorption parameter, carboxy-terminal cross-linked type-I collagen telopeptide (P < 0.05). Both sodium fluoride and ibandronate resulted in significant decreases in the serum concentration of osteoprotegerin after 9 months (P < 0.001). CONCLUSIONS: The findings of the present study show that both sodium fluoride and ibandronate are effective in combination with calcium and vitamin D substitution in the management of osteopenia and osteoporosis in patients with Crohn's disease. Both agents are safe and well tolerated, and induce continuous increases in lumbar bone density.

Bone Density↗
PubMedDate not supplied

Single-monthly-dose vitamin D supplementation in elderly patients.

OBJECTIVE: To determine the serum levels of calcidiol and calcitriol in 2 men and in 21 postmenopausal, primarily elderly women receiving hormone replacement therapy, orally administered calcium citrate, and an additional supplement of 50,000 IU of vitamin D (1.25 mg of cholecalciferol) once monthly for various periods. METHODS: We determined plasma calcidiol and calcitriol levels at various times, ranging from -1 to +60 days after intake of a single dose of 1.25 mg of vitamin D in 10 initial or short-term users (1 to 6 months) and in 13 women who had been using this monthly regimen for several years. The primary concerns were the safety and adequacy of the blood levels achieved with a regimen that encouraged compliance. RESULTS: In long-term users of monthly vitamin D regimens, calcidiol levels were usually slightly in excess of the upper limit of normal (that is, >52 ng/mL [>130 nmol/L]) at all times throughout the month; in contrast, calcitriol levels exceeded the normal range (8 to 52 pg/mL [19 to 125 pmol/L]) only once in 18 samplings. In short-term users, calcidiol levels exceeded the normal range only once shortly after intake, and no calcitriol level exceeded the normal range. CONCLUSION: Once-a-month dosage of 50,000 IU (1.25 mg) of vitamin D in elderly women receiving hormone replacement therapy plus supplemental calcium and uncontrolled generic multivitamin intake yields calcitriol levels within the normal range, even after years of use of this regimen. Calcidiol levels exceeded the normal range at all times in long-term users but only once in short-term users. Calcidiol concentrations, however, were found to be far below levels (>150 ng/mL [>375 nmol/L]) that might produce hypercalciuria or hypercalcemia.

Journal Article↗
PubMed1998

Iron status, menarche, and calcium supplementation in adolescent girls.

The effects of growth, menstrual status, and calcium supplementation on iron status were studied over 4 y in 354 girls in pubertal stage 2 who were premenarcheal at baseline (x+/-SD age: 10.8+/-0.8 y). Girls were randomly assigned to placebo or treatment with 1000 mg Ca/d as calcium citrate malate. Anthropometric characteristics, bone mass, and nutritional status were measured biannually; ferritin was measured annually; and red blood cell indexes were determined at 4 y. The simultaneous effects of iron intake and menstrual status on serum ferritin, after change in lean body mass (LBM) was controlled for, were evaluated in subjects in the upper and lower quartiles of cumulative iron intake. The average maximal accumulation of LBM (386 g/mo; 95% CI: 372, 399) occurred 0.5 y before the onset of menarche. Change in LBM was a significant predictor of serum ferritin (P < 0.0001), with a negative influence on iron status (t ratio=-4.12). The 2 fitted mathematical models representing ferritin concentrations of subjects in the upper and lower quartiles of cumulative iron intake were significantly different (P < 0.018). The regression line of the ferritin concentration in menstruating girls with high iron intakes had a less negative slope than the line fit to serum ferritin concentrations in girls with low iron intakes (NS). Serum ferritin concentrations at 0, 1, 2, 3, and 4 y were not significantly different between groups. In addition, there was no significant difference between groups in any of the red blood cell indexes. In summary, growth spurt and menstrual status had adverse effects on iron stores in adolescent girls with low iron intakes (<9 mg/d), whereas long-term supplementation with calcium (total intake: approximately 1500 mg/d) did not affect iron status.

Adolescent↗
PubMed1998

Comparison of erosion of dental enamel by four drinks using an intra-oral applicance.

There are several causes of erosion - acidic foods and drinks have been implicated and reducing their erosive potential would seem an important area of research. Calcium-citrate-malate (CCM) appeared to have potentially useful properties as an anti-erosion additive. The study aims were to test the ability of an intra-oral enamel slab system to measure erosion and to compare the erosive potential of a citric acid-based orange juice drink either with or without added CCM and a positive and negative control. Eleven adults wore an upper removable appliance for four periods each of 6 days. Each appliance held two enamel slabs which were inserted into the test drinks for 15 min 4 times a day for 6 days. Loss of enamel was quantified by profiling casts of the enamel slabs taken before and after the test period. Loss of enamal was greatest during exposure to a diet phosphoric acid-based cola drink (p < 0.001) but was similar during exposure to the two citric acid-based orange drinks, with or without CCM, and distilled water. The loss of surface enamel measured from a scanning electron micrograph agreed well with the measurement obtained by profilometry. It can be concluded that (a) the intra-oral enamel slab system was able to discriminate between drinks in their erosive potential, and (b) it was not possible to determine if CCM had any potential for reduction in erosion in an acid beverage as the level of erosion observed for both the critic acid-based orange drinks was not statistically significantly different from that observed with distilled water.

Acids↗
PubMed1998

Agglomeration inhibition reflected stone-forming activity during long-term potassium citrate therapy in calcium stone formers.

OBJECTIVES: The agglomeration of preformed crystals of calcium oxalate has been hypothesized to be the rate-limiting step in renal stone-forming activity (SFA). The effect of urine on the in vitro inhibition of agglomeration of seed crystals of calcium oxalate monohydrate, designated [tm], has been used to monitor SFA in calcium oxalate stone formers (CaOxSF). The objective of the present study was to determine whether [tm] could be used to help monitor the long-term effectiveness of oral potassium citrate therapy (K-Cit-Rx) in CaOxSF. METHODS: Clinic and radiographic (or ultrasound) reports were evaluated for 80 patients, aged 20 to 72 years, 55 men and 25 women, who were treated with oral K-Cit for recurrent calcium oxalate urolithiasis at the Ochsner Stone Clinic between January 1992 and July 1996. Seventy-five of these patients had at least one 24-hour citrate excretion rate of less than 3.0 mm/day before or after K-Cit-Rx. SFA graded on a scale of -2 to +2 by radiographic criteria was combined with information on stone passage to evaluate clinical stone status, and 24-hour urine collections were evaluated for volume, pH, calcium, citrate, uric acid, oxalate, creatinine, and [tm] on free diet before and after 6 to 53 months of K-Cit-Rx. Historical information on procedures performed for urolithiasis before and on K-Cit-Rx was also reviewed. RESULTS: K-Cit-Rx resulted in increased urine pH (P <0.0001) and decreased calcium (P=0.0475), [tm] (P=0.0045), number of stones passed per year (P=0.0016), and remedial procedures per year (P <0.0001). Patients taking allopurinol in addition to K-Cit required higher doses (P <0.0001) of K-Cit to control their disease, had lower pretreatment urine pH (P=0.0493), and showed greater increase in urine citrate (P=0.0092) than those on K-Cit alone. Those taking high-dose K-Cit were younger (P=0.0363) and showed greater decrease in SFA (P=0.0005) than those taking lower doses. A small group of 10 medication refractory patients, who retained (n=9) or increased (n=1) their stone burden during K-Cit-Rx, was identified. Compared with the medication-responsive group, the refractory patients were older (P=0.0124), and had greatly increased SFA (P <0.0001) and higher (P=0.0347) urine pH before and during (P=0.0173) treatment (data not shown). CONCLUSIONS: The data confirm that [tm] can be used not only to verify previously documented stone formation rate but also to help evaluate the long-term effectiveness of therapy. In this report, changes in [tm] after K-Cit-Rx reflected decreased stone formation rate and decreased remedial procedures.

Adult↗
PubMed1978

Purification and properties of porcine platelet aggregating factor.

Porcine platelet aggregating factor was purified from porcine plasma by a rapid batch procedure which included polyethylene glycol precipitation and adsorption on calcium citrate. The aggregating factor was separated from antihemophilic factor by gel chromatography in the presence of 1 M MgCl2. It appeared homogenous when examined by immuno- or SDS-gel electrophoresis. The molecular weight was estimated to be 10 million by exclusion chromatography. After reduction, subunit molecular weight, by sodium dodecyl sulfate (SDS)-gel electrophoresis, was 225 000. Amino acid and carbohydrate composition were similar to those reported for the bovine material. The porcine platelet aggregating factor was found to have no free sulfhydryl groups or exposed disulfide bonds. Binding of formalin-fixed washed human platelets to the aggregating factor linked to Sepharose was inhibited in 0.5 M NaCl or 2.7 M urea and reversed by the presence of free aggregating factor in a concentration-dependent manner. Ristocetin had little or no discernible effect on binding.

Amino Acids↗