Bone density and skeletal metabolism are altered in idiopathic hypercalciuria

OBJECTIVE

To study bone density in hypercalciuric patients, when classified according to the main metabolic defect.

METHODS

We studied 49 patients, aged 19-60 years with calcium stones and idiopathic hypercalcuria. All subjects underwent an evaluation of mineral metabolism and a spinal and femoral DEXA measurement. Then, patients were classified as having Fasting (FH, 31 subjects) or Absorptive (AH, 18 patients) Hypercalciuria according to a standard oral calcium load.

RESULTS

Spinal bone density was lower only in FH patients as compared to controls (p <0.001). Bone alkaline phosphatase and urine hydroxyproline were higher with respect to controls only in patients with FH (p <0.005 and p <0.015, respectively). After low calcium diet, hydroxyproline excretion continued to be higher in FH patients (p <0.05). Although in the normal range, serum and urine uric acid were higher in hypercalciuric subjects (p <0.03 and p <0.005, respectively); blood pH was lower in hypercalciuric patients than in controls (p <0.01). In FH patients urine hydroxyproline negatively correlated with spinal and femoral density (p <0.001 and p <0.005, respectively), and blood pH positively correlated with spinal density.

CONCLUSIONS

a disordered bone metabolism and bone loss are present only in patients with fasting hypercalciuria. An excessive acid load, possibly of dietary origin, might be involved as a pathogenetic factor.

Cytokine levels in osteoarthrosis patients undergoing mud bath therapy

Osteoarthritis is an important rheumatic condition characterized by the progressive destruction of cartilage. The pathophysiologic phenomena leading to the pathologic changes in the joint appear to result from biomechanical factors and activation of final common pathways of tissue damage influencing chondrocyte homeostasis and a functional program. Several cytokines and growth factors are reported to be responsible for inflammation and cartilage degradation. Among these, IL-1 and TNF alpha have been suggested as important in promoting cartilage inflammation and tissue destruction, while IGF I has a protective influence on cartilage structure. Chondrocytes and their metabolism have gained interest as targets of drug intervention; the results of this study confirm that mud bath therapy is also able to influence chondrocyte activities. Our data suggest that mud bath therapy influences cytokines related to osteoarthrosis pathomechanism and maintenance, and encourage further investigations to evaluate possible synergism between pharmacological treatment and mud bath therapy.

Bone density and skeletal metabolism in patients with orthotopic ileal neobladder

The interposition of a bowel segment as a bladder substitute into the urinary tract may result in impaired calcium metabolism. We studied 25 male patients (aged 45 to 77 yr) who had undergone a Vescica Ileale Padovana (VIP) reconstruction following cystectomy 29 to 75 mo before. Bone mineral density of the spine and femur was measured by dual x-ray absorptiometry. Blood and 24-h urine samples were analyzed for the main parameters of bone metabolism. Sixteen healthy men were enrolled as a control group. Although blood pH did not differ between patients and control subjects, VIP subjects showed lower levels of plasma HCO3- (P < 0.005) and higher serum chloride (P < 0.001). Bone alkaline phosphatase was higher (P < 0.001), and urine calcium, phosphate, and creatinine levels were lower in VIP patients (P < 0.01, P < 0.01, and P < 0.05, respectively). Bone mineral density at the femoral neck (P < 0.03) and Ward's triangle (P < 0.05) was decreased in VIP patients. When subdivided according to time since operation, patients who had the ileal neobladder implanted for a shorter period of time showed lower blood pH (P < 0.03) and urine calcium (P < 0.05) levels and higher urinary hydroxyproline (P < 0.02). Duration of the ileal neobladder was positively correlated with PTH (r = 0.46, P < 0.03) and blood pH (r = 0.47, P < 0.02). Furthermore, pH values were positively correlated with urine calcium (r = 0.48, P < 0.02). In conclusion, in patients with ileal neobladder, a mild metabolic acidosis is responsible for an increased bone turnover and lower bone mass. Moreover, a decrease over time in the absorption capacity of the ileal pouch might result in calcium malabsorption, which represents an additional risk factor for reduced bone mass in these patients.

Self-report of difficulty in performing functional activities identifies a broad range of disability in old age

OBJECTIVE

To describe a broad range of physical disability by examining the association between a four-level measure of disability, based on self-report of difficulty in performing functional activities, and previously identified risk factors for disability.

DESIGN

Cross-sectional.

SETTING

Community-based.

PARTICIPANTS

A total of 2373 noninstitutionalized men and women aged 65 and older from the Veneto Region of Italy.

MEASUREMENTS

Odds ratios for the association of the four levels of disability (none, mild, moderate, and ADL disability) differentiated by this new measure with known risk factors for physical disability.

MAIN RESULTS

This summary measure of physical disability distinguished older persons with disability from the population typically classified as nondisabled. Twenty-one percent of study participants were identified as having Activities of Daily Living (ADL) disability (defined as self-report of difficulty in one or more ADLs), and an additional 40% had mild or moderate disability based on degree of difficulty in Instrumental Activities of Daily Living (IADLs) and physical functional activities. Hip fracture and lower extremity performance were strongly independently associated with each level of disability. The association of a range of established risk factors for disability and health care utilization measures with the levels of disability identified in our study, and the trend toward increasing odds with increasing disability, provide evidence of the construct validity of this measure.

CONCLUSIONS

Self-report of difficulty in performing functional activities identifies older persons with physical disability not ascertained by self-report of the need for help, the measure typically used to identify disability in older populations. Further studies should evaluate the potential for self-reported difficulty in functional activities to predict important disability-related outcomes.

Continuous and cyclical clodronate therapies and bone density in postmenopausal bone loss

OBJECTIVE

To evaluate the effectiveness of different clodronate regimens in postmenopausal osteoporosis.

METHODS

In groups of 20, 60 women were randomly assigned to one of three treatments: oral calcium, 1000 mg/day; oral calcium plus oral clodronate, 400 mg/day; oral calcium plus oral clodronate, 400 mg/day for 30 days, followed by a 60-day period of calcium supplement alone. This last regimen was repeated four times in the 12-month study period.

RESULTS

Patients who received calcium alone showed a decline in spinal bone mass, both after 6 and 12 months (P < .03 and P < .005, respectively); femoral density in this group also decreased after 6 and 12 months (P < .002 and P < .05, respectively). On the other hand, both clodronate-treated groups had increased levels of lumbar bone mass compared with controls, both after 6 and 12 months of therapy. However, at the end of the study, patients treated with cyclical clodronate had higher spinal bone mass compared with those treated continuously (3.32 +/- 0.71 versus 0.43 +/- 0.89%, P < .02). After 6 months, femoral bone density was significantly higher both in subjects treated with clodronate, both cyclically and continuously (P < .01), compared with controls. Continuous clodronate treatment resulted in a clear fall in biochemical indices of bone resorption, together with a consequent decrease in osteocalcin at 6 (P < .02) and 12 months (P < .003) and a significant increase in parathyroid hormone after 12 months (P < .001) of therapy.

CONCLUSION

One-year treatment with clodronate induces a gain in bone mass, especially in the spine. The continuous regimen does not result in any further benefit in lumbar bone density over the cyclical one, probably because of a greater suppression of bone turnover.

[The epidemiology of osteoporotic fractures]

Fractures represent the most important consequence of osteoporosis, as well as the major determinant of the socio-economic costs of the disease. Distal forearm, vertebrae and proximal femur fractures are frequently associated with the disease. Colles' fractures generally occur in women, showing a progressive increase in incidence after the onset of menopause, and reaching a plateau at the age of 65 years. Vertebral fractures are often painless and fortuitously diagnosed so that there are not many epidemiological data available. However, incidence rates appear to increase steadily with aging in women, while accelerating only in later life in men. In the elderly population, spine deformities due to vertebral fractures can contribute to the worsening of concurrent diseases. Fractures of the proximal femur represent the gold standard for epidemiological studies on osteoporosis. Their incidence increases exponentially in women 70 years old and over, and in men aged 80 or older. Moreover, that, femoral fractures are associated with a substantial risk of nonself sufficiency and mortality. Osteoporosis-related costs vary greatly among countries, not only because of a different incidence of the disease, but also due to the different emphasis on prevention, hospitalization, and treatment. The current dramatic increase of the elderly population exhorts against the postponing of a global strategy for preventing and treating the disease.

Heart rate and metabolic response to burn injury in humans

BACKGROUND

Although frequently done, estimating the energy requirements of individual burn patients without measuring their resting metabolic rate is a less than satisfactory method of evaluation.

METHODS

We tested whether heart rate, which relates to the energy expenditure during physical activity, is also associated with postburn hypermetabolism (calculated as percentage increase of resting metabolic rate above the predicted normal fasting resting metabolic rate). Twenty-three patients [12 men and 11 women, aged 38 +/- 13 years (mean +/- SD); weight, 71.6 +/- 14.8 kg; body mass index, 25.4 +/- 3.6; total burn surface area, 35.3 +/- 17.8% (percentage of body surface)] were studied weekly for 3 weeks after an overnight fast.

RESULTS

Measured resting metabolic rates and heart rates were 2016 +/- 497 kcal/d, 101 +/- 13 bpm (n = 19); 2231 +/- 485 kcal/d, 107 +/- 13 bpm (n = 18); and 1903 +/- 598 kcal/d, 99 +/- 14 bpm (n = 11) for weeks 1, 2, and 3, respectively. Postburn hypermetabolism was +36% +/- 19%, +55% +/- 27%, and +36% +/- 35% in the first, second, and third week, respectively. In each week postburn hypermetabolism correlated with heart rate (r = 0.65, p = .003; r = 0.69, p = .001; and r = 0.80, p = .002, respectively). Only in the second week did postburn hypermetabolism correlate with total burn surface area (r = 0.52, p = .02); there was no correlation with body temperature. In a multiple regression analysis, predicted resting metabolic rate, heart rate, and total burn surface area together explained 77% of all of the variance observed in the 48 fasting resting metabolic rates that were measured in the study (r2 = 0.77, p < .0001), and each of these variables also had a significant partial correlation with fasting resting metabolic rates (r2 = 0.45, p < .0001; r2 = 0.29, p < .0001; and r2 = 0.03, p < .03, respectively).

CONCLUSIONS

In burn patients, variability in heart rate is associated with a significant part of postburn hypermetabolism variability. Therefore, heart rate may be considered a useful variable to be used for the evaluation of the energy requirements of severely burned patients.

Bone density and mineral metabolism in thyroidectomized patients treated with long-term L-thyroxine

1. A decreased bone mass has been reported in patients with endogenous hyperthyroidism, but the effect on bone density and mineral metabolism of thyroxine administration in thyroidectomized patients is still controversial. To further contribute to this debate, we studied 25 women thyroidectomized for thyroid cancer on long-term treatment with thyroid-stimulating hormone-suppressive doses of L-thyroxine. Twenty-one sex- and age-matched normal subjects were also studied as a control group. 2. The bone density of the spine and serum calcitonin, calcitriol and parathyroid hormone concentrations were not different when the whole patient group was compared with the control subjects, nor when the patients and control subjects were compared according to their menopausal status. However, post-menopausal thyroidectomized patients showed significantly lower bone mass (P < 0.001) than premenopausal patients. 3. L-Thyroxine-treated patients showed significantly higher levels of bone alkaline phosphatase and urine hydroxyproline excretion than control subjects (P < 0.003 and P < 0.001, respectively). These differences were still present when patients and control subjects were analysed according to their menopausal status. However, bone alkaline phosphatase was significantly higher in postmenopausal than in premenopausal women only in L-thyroxine-treated patients (P < 0.05). In postmenopausal L-thyroxine-treated patients a negative correlation between time since menopause and bone mass (P < 0.05) and a positive correlation between bone alkaline phosphatase and hydroxyproline excretion (P < 0.03) were also found.(ABSTRACT TRUNCATED AT 250 WORDS)

SP-A, SP-B, and SP-C in surfactant subtypes around birth: reexamination of alveolar life cycle of surfactant

Transformations of surfactant after secretion are incompletely understood. To clarify them, we lavaged lungs in fetuses and in newborn rabbits, fractionated the lavage fluid by differential and density gradient centrifugation, and analyzed the distribution of surfactant protein (SP) phospholipids, SP-A, SP-B, and SP-C. Furthermore, we administered into trachea of newborn rabbits labeled surfactant and compared the alveolar clearance of SP-A, SP-B, SP-C and saturated phosphatidylcholine. We found that, in the fetus, secreted lamellar bodies contain all components of surfactant, except a small amount of SP-A. As breathing starts and new surfactant subtypes are generated, the proteins are mostly associated with dense subtypes, but SP-B and SP-C are especially concentrated in dense materials that contain minor amounts of phospholipids and SP-A. Furthermore, we found that, during breathing, alveolar surfactant is degraded into more than one type of remnant, that the lavage fluid contains a pool of SP-A not associated with membranes, and that SP-A, SP-B, and SP-C are all turned over at a faster rate than saturated phosphatidylcholine.

Effect of ursodeoxycholic acid on intracellular pH in a bile duct epithelium-like cell line

Recent studies in perfused livers and isolated hepatocytes indicate that ursodeoxycholic acid-induced HCO3-rich hypercholeresis originates at the ductule/duct level. The bile duct epithelium may be involved in bile alkalinization by passively reabsorbing the protonated unconjugated ursodeoxycholic acid, by directly secreting in response to an ursodeoxycholic acid-induced increase in acid/base transporter activity or by taking up UDCA- in exchange for a base equivalent. To investigate these processes in more detail, we studied the effects of ursodeoxycholic acid on intracellular pH in SK-ChA-1, a well-differentiated human cholangiocarcinoma cell line similar to bile duct epithelium in terms of intracellular pH regulatory mechanisms and morphological markers. Intracellular pH changes were monitored with a microfluorimetric setup using the fluorescent indicator 2'-7'-bis(2-carboxyethyl)-5,6,carboxy fluorescein. Administration of 50 to 1,000 mumol/L UDCA in the absence of HCO3 caused dose-dependent intracellular acidification (intracellular pH = -0.13 +/- 0.03 pH/U after 500 mumol/L ursodeoxycholic acid). Acidification was not prevented by preincubation of cells with 0.5 mmol/L 4,4-diisothiocyanatostilbene-2,2,-disulfonic acid (DIDS) for 30 min or by furosemide administration (1 mmol/L), thus ruling out the stimulation of Cl/HCO3 exchange or the presence of an ursodeoxycholic acid/base exchange. Ursodeoxycholic acid also acidified human fibroblasts, a cell type with no transport capability for ursodeoxycholic acid. In addition, direct measurement of the activities of the three major acid/base transporters in Sk-ChA-1 cells (Na+/H+ exchange, sodium-dependent and sodium-independent Cl/HCO3 exchange) failed to show significative differences between cells treated with 500 mumol/L UDCA and controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Synthetic parathyroid hormone-like protein (1-74) is anabolic for bone in vivo

Parathyroid hormone-related protein (PTHRP) has recently been purified from human tumors associated with the syndrome of humoral hypercalcemia of malignancy. The gene encoding PTHRP has been cloned, and based on predicted amino acid sequence, polypeptides comprising the first 36 [36Tyr(1-36) PTHRP amide] and 74 [(1-74)PTHRP] amino acids have been synthesized. Human (h) PTHRP (1-36) and (1-74) are potent bone-resorbing agents, and are catabolic for bone in vivo when given continuously at high doses. Bovine parathyroid hormone (bPTH) (1-34) is also catabolic for bone at high dose levels, but when given in low doses for weeks to months, it is anabolic. Although PTHRP possess several PTH-like properties in bone, hPTHRP (1-34) is reported to be only weakly anabolic in vivo. As polypeptide length influences PTHRP action, we evaluated hPTHRP(1-74) as an anabolic agent for bone in vivo. Twenty-four 4-week-old male Sprague-Dawley rats were given daily subcutaneous injections of hPTHRP(1-74) (1 and 2 nmol/100 g body weight, bw), bPTH(1-34) (4 nmol/100 g bw) or vehicle. Rats were sacrificed on day 12, and serum calcium, phosphorus, and 1,25 dihydroxyvitamin D and femoral bone dry weight, calcium content, and hydroxyproline content were measured. Serum calcium and phosphorus were equivalent in all groups. A significant increase in dry bone weight was observed in both PTHRP-treated groups compared with controls. PTHRP also caused a significant, dose-dependent increase in bone calcium and hydroxyproline content. Results of these studies indicate that PTHRP (1-74) is anabolic for bone in vivo when administered at low-dosage levels for a prolonged period.

Trichlormethiazide and oral phosphate therapy in patients with absorptive hypercalciuria

In a short-term prospective study 36 patients with absorptive hypercalciuria were initially treated with diet alone followed by either trichlormethiazide (4 mg. per day) or oral neutral phosphate (1,500 mg. of elemental phosphorus per day) for 6 weeks. Study subjects were then crossed over to the second drug for an additional 6 weeks. In response to dietary treatment urinary calcium decreased from a pre-treatment value of 346 +/- 63 mg. per 24 hours to 308 +/- 90 mg. per 24 hours. Oral phosphate therapy caused a further decrease in urinary calcium to 218 +/- 85 mg. per 24 hours, an over-all decrease of 37 per cent. Parathyroid function did not change significantly with phosphate administration but circulating levels of 1,25-dihydroxyvitamin D decreased by 22 per cent (73 +/- 12 to 57 +/- 16 pg. per ml., p less than 0.001). Pre-treatment renal phosphate threshold did not correlate with the response to oral phosphate administration. Trichlormethiazide treatment led to a 34 per cent decrease in urinary calcium with a mean value on treatment of 228 +/- 80 mg. per 24 hours. 1,25-Dihydroxyvitamin D levels decreased by 10 per cent. Pre-treatment fasting calcium excretion, parathyroid function and 1,25-dihydroxyvitamin D levels did not correlate with the response to trichlormethiazide. We conclude that both drugs by pharmacological means improve the biochemical abnormalities in absorptive hypercalciuria and should be efficacious in its treatment.

Renal phosphate transport in humoral hypercalcemia of malignancy

Fisher rats bearing the H-500 Leydig cell tumor (LCT) develop humoral hypercalcemia of malignancy (HHM), which is accompanied by hypophosphatemia and hyperphosphaturia. To better define the mechanisms underlying the changes in phosphate metabolism, the activity of sodium-dependent phosphate uptake (Na+-Pi) in microvillus membrane vesicles (MMV) isolated from the renal cortex of LCT-bearing rats was studied. Ten days after tumor transplantation the animals became hypercalcemic, hypophosphatemic, and hyperphosphaturic, and LCT-MMV showed a specific decrease in Na+-Pi. A kinetic analysis revealed evidence for both a high- and a low-affinity system of Na+-Pi. The Vmax of both the low-affinity system and the high-affinity system were significantly reduced in LCT-MMV. These changes in Na+-Pi transport were similar to those induced by parathyroid hormone. In day-10 tumor-bearing animals, daily injections of dichloromethylene diphosphonate (2.5 mg.kg-1.day-1) prevented the onset of hypercalcemia but not the reduction in Na+-Pi in LCT-MMV. Our data suggest that in this animal model of HHM there is a specific and persistent impairment of Na+-Pi uptake at the level of the renal cortical brush-border membrane, which contributes to the derangement in phosphate metabolism.

Synthetic and partially-purified adenylate cyclase-stimulating proteins from tumors associated with humoral hypercalcemia of malignancy inhibit phosphate transport in a PTH-responsive renal cell line

Hypophosphatemia and hyperphosphaturia characteristically occur in patients with humoral hypercalcemia of malignancy (HHM). To determine if a tumor product causes these abnormalities in phosphate metabolism, rather than, for example, hypercalcemia, we investigated the effect of partially-purified adenylate cyclase-stimulating activity (ACSA) from human and animal HHM-associated tumors on sodium-dependent phosphate transport (Na PiT) in a PTH-responsive renal epithelial cell line. Thirty minute exposure to 7 X 10(-10) MbPTH (1-34) equivalents of ACSA from the human and animal tumors, reduced NaPiT by 20% and 14%, respectively. We also recently isolated an adenylate cyclase-stimulating protein (hACSP) from two human tumors associated with HHM and identified a cDNA clone for this protein which encodes a 141 amino-acid peptide. Based on the deduced amino-acid sequence, we synthesized tyr36 (1-36) hACSP. This synthetic peptide induced a 22% decrease in the initial rate of NaPiT by the epithelial monolayer. Its inhibitory activity was roughly equipotent to that of bPTH (1-34). We conclude that the ACSP derived from HHM-associated tumors decreases phosphate transport in renal epithelial cells. This peptide appears to play a key role in mediating the changes in phosphate metabolism in this syndrome.

Captopril in the treatment of hypertension in type I and type II diabetic patients

Ten type I and 10 type II hypertensive diabetic patients were treated for 12 weeks with captopril (50 mg twice daily). Good control of blood pressure was achieved without any significant adverse effect on carbohydrate metabolism or renal haemodynamics and without evidence of glomerular or tubular damage.

Mineral metabolism and bone mineral content in rheumatoid arthritis. Effect of corticosteroids

An evaluation of mineral metabolism was performed in 41 patients with RA and the pertinent data were compared to bone mineral content in patients either untreated or treated with different doses of corticosteroids. Our study confirms that osteoporosis is a common finding even in rheumatoid patients never treated with corticosteroids. Moreover, in patients treated with such drug the loss of bone mineral content was related to the dosage rather than to the length of treatment. In all cases no overt biochemical derangement was observed. According to our study, parathyroid hormone does not seem to influence the development of osteoporosis in rheumatoid arthritis, while a relative deficiency of calcitonin along with an inadequate vitamin D metabolism could play some role.

Rapidly Changing Radio Images

Differences in total transit time can give rise to images that expand at arbitrarily high speed. Two versions of a model based on this idea can account for the varying microwave structure reported for the quasar 3C 279. Other possible examples are suggested.