[Bone and metabolism]

Bone is now considered as a particular endocrine organ. Its endocrine function is not yet fully understood and has been the subject of several conferences at the European Society of Endocrinology Congress 2018. Bone regulates phosphate metabolism by secreting fibroblast growth factor 23; it also regulates glucose metabolism via osteocalcin and energy metabolism, thanks to lipocalin 2, a new hormone acting on the brain. In addition, the incidence of diabetes continues to grow, and its impact on bone has been demonstrated, with an increased risk of fractures regardless the type of diabetes. The mechanism of bone fragility in this disease is not fully known but it involves a decrease in bone turnover and bone demineralization. Recent findings on the role of bone on glucose and mineral metabolism could open therapeutic perspectives, especially for the treatment of diabetes or obesity.

[Update 2017 of the KDIGO guidelines on Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD). What are the real changes?]

Guidelines for the assessment, diagnosis and therapy of the alterations that characterize the CKD-MBD are an important support in the clinical practice of the nephrologist. Compared to the KDIGO guidelines published in 2009, the 2017 update made changes on some topics on which there was previously no strong evidence both in terms of diagnosis and therapy. The recommendations include the diagnosis of bone anomalies in CKD-MBD and the treatment of mineral metabolism abnormalities with particular regard to hyperphosphataemia, calcium levels, secondary hyperparathyroidism and anti-resorptive therapies. The Italian Study Group on Mineral Metabolism, in reviewing the 2017 recommendations, aimed to assess the weight of the evidence that led to this update. In fact, on some topics there has not been a substantial difference on the degree of evidence compared to the previous guidelines. The Italian Study Group emphasizes the points that may still reserve critical issues, including interpretation, and invites an evaluation that is articulated and personalized for each patient.

Asfotase alfa treatment for 1 year in a 16 year-old male with severe childhood hypophosphatasia

We describe the clinical outcome of asfotase alfa therapy in a 16-year-old boy with severe childhood hypophosphatasia (HPP), who began therapy at age 15 years. The patient was diagnosed with HPP at age 2 years when he presented with genu varum and premature loss of primary teeth. He had a history of multiple fractures requiring 16 orthopedic surgeries with rod and pin placement in his lower extremities. He had chronic skeletal pain and used cane to ambulate with great difficulty. His height Z score at age 15 years was - 5. He had severe scoliosis and deformity of both legs. Bone radiograph showed hypomineralization and characteristic "tongues" of radiolucency in the distal radius and ulna. His serum alkaline phosphatase level was stable, with elevated serum pyridoxal 5'-phosphate and urine phosphoethanolamine, consistent with HPP. He was started on asfotase alfa 2 mg/kg given subcutaneously thrice weekly. He had marked clinical improvement in mobility with no report of pain after 3 months of treatment. At 6 month, he walked without cane and participated in outdoor activities with peers. Bone radiograph at 6 months showed striking improvement in previous radiolucent areas. At 9 months, his annualized growth velocity was 9.5 cm/year, while growth velocity of arm span was 12 cm/year. However, at 12 months, he was noted to have worsening scoliosis from 60 degrees before therapy to 110 degrees, with a slight decrease in height, necessitating a spinal fusion surgery. In conclusion, treatment with asfotase alfa significantly improved physical function, pain, overall quality of life, and skeletal radiographic findings in this patient. Close monitoring for progression of scoliosis in adolescents with HPP treated with asfotase alfa is recommended.

TDF and quantitative ultrasound bone quality in African patients on second line ART, ANRS 12169 2LADY sub-study

BACKGROUND

Bone demineralization, which leads to osteoporosis and increased fracture risk, is a common metabolic disorder in HIV-infected individuals. In this study, we aimed to assess the change in bone quality using quantitative ultrasound (QUS) over 96 weeks of follow-up after initiation of second-line treatment, and to identify factors associated with change in bone quality.

METHODS AND FINDINGS

In a randomized trial (ANRS 12169), TDF and PI-naïve participants failing standard first-line treatment, from Burkina Faso, Cameroon, and Senegal were randomized to receive either TDF/FTC/LPVr, ABC/ddI/LPVr or TDF/FTC/DRVr. Their bone quality was assessed using calcaneal QUS at baseline and every 24 weeks until week 96. Stiffness index (SI) was used to measure bone quality. Out of 228 participants, 168 (74%) were women. At baseline, median age was 37 years (IQR: 33-46 years) and median T-CD4 count was 199 cells/μl (IQR: 113-319 cells/μl). The median duration of first-line antiretroviral treatment (ART) was 52 months (IQR: 36-72 months) and the median baseline SI was 101 (IQR: 87-116). In multivariable analysis, factors associated with baseline SI were sex (β = -10.8 [-18.1,-3.5] for women), age (β = -8.7 [-12.4,-5.1] per 10 years), body mass index (BMI) (β = +0.8 [0.1,1.5] per unit of BMI), and study site (β = +12.8 [6.5,19.1] for Cameroon). After 96 weeks of second-line therapy, a reduction of 7.1% in mean SI was observed, as compared with baseline. Factors associated with SI during the follow-up were similar to those found at baseline. Exposure to TDF was not associated with a greater loss of bone quality over time.

CONCLUSION

Bone quality decreased after second-line ART initiation in African patients independently of TDF exposure. Factors associated with bone quality include age, sex, baseline BMI, study site, and duration of follow-up.

Osteoporosis: A Future Public Health Problem for Israel? Medical and Legal Obligations

Starvation in early life can lead to premature metabolic syndrome and bone demineralization. Osteoporosis in the Jewish population may not yet be a recognized syndrome, but the harsh conditions to which Holocaust survivors were exposed may have increased the incidence of the condition. Immigrants and refugees who came to Israel from East Africa and Yemen - whether decades ago or more recently - may have been at increased risk of under-nutrition during pregnancy, affecting both the mother and consequently the offspring. This malnutrition may be further exacerbated by rapid overfeeding in the adopted developed country. This problem was also recognized at the turn of the 21st century in poor and underdeveloped countries and is becoming a global public health issue. In this review, the risks for premature metabolic syndrome and bone demineralization are enumerated and preventive measures outlined.

AAV8-mediated expression of N-acetylglucosamine-1-phosphate transferase attenuates bone loss in a mouse model of mucolipidosis II

Mucolipidoses II and III (ML II and ML III) are lysosomal disorders in which the mannose 6-phosphate recognition marker is absent from lysosomal hydrolases and other glycoproteins due to mutations in GNPTAB, which encodes two of three subunits of the heterohexameric enzyme, N-acetylglucosamine-1-phosphotransferase. Both disorders are caused by the same gene, but ML II represents the more severe phenotype. Bone manifestations of ML II include hip dysplasia, scoliosis, rickets and osteogenesis imperfecta. In this study, we sought to determine whether a recombinant adeno-associated viral vector (AAV2/8-GNPTAB) could confer high and prolonged gene expression of GNPTAB and thereby influence the pathology in the cartilage and bone tissue of a GNPTAB knock out (KO) mouse model. The results demonstrated significant increases in bone mineral density and content in AAV2/8-GNPTAB-treated as compared to non-treated KO mice. We also showed that IL-6 (interleukin-6) expression in articular cartilage was reduced in AAV2/8-GNPTAB treated ML II mice. Together, these data suggest that AAV-mediated expression of GNPTAB in ML II mice can attenuate bone loss via inhibition of IL-6 production. This study emphasizes the value of the MLII KO mouse to recapitulate the clinical manifestations of the disease and highlights its amenability to therapy.

Bone demineralisation in a large cohort of Wilson disease patients

AIMS AND BACKGROUND

We compared the bone mineral density (BMD) of adult Wilson disease (WD) patients (n = 148), with an age- and gender-matched healthy control population (n = 148). Within the WD cohort, correlations of BMD with WD disease parameters, lab results, type of treatment and known osteoporosis risk factors were analysed.

METHODS

Hip and lumbar spine absolute BMD and T-score were measured by dual-energy X-ray absorptiometry. Osteoporosis and osteopenia were defined as a T-score ≤ -2.5, and between -1 and -2.5, respectively.

RESULTS

There were significantly more subjects with abnormal T-scores in the WD population (58.8%) than in the control population (45.3%) (χ(2) = 6.65, df = 2, p = 0.036), as there were 50.0% osteopenic and 8.8% osteoporotic WD patients, vs. 41.2% and 4.1%, respectively, in the controls. Especially L2-L4 spine BMD measurements (BMD and T-scores) differed significantly between the WD population and matched controls. L2-L4 spine BMD for WD patients was on average 0.054 g/cm(2) (5.1%) lower than in matched normal controls (0.995 ± 0.156 vs 1.050 ± 0.135; p = 0.002). We found no significant correlation between BMD values and any of the WD disease parameters (e.g. the severity of liver disease), lab results, type of treatment or known osteoporosis risk factors. Duration of D-penicillamine treatment was negatively correlated with femoral BMD value, but in a clinically irrelevant manner, compared to age and gender. Importantly, BMD remained significantly lower in WD patients (n = 89) vs. controls after excluding WD patients with cirrhosis (p = 0.009).

CONCLUSIONS

Our study suggests that WD is intrinsically associated with bone demineralisation.

Pulsed focused ultrasound treatment of muscle mitigates paralysis-induced bone loss in the adjacent bone: a study in a mouse model

Bone loss can result from bed rest, space flight, spinal cord injury or age-related hormonal changes. Current bone loss mitigation techniques include pharmaceutical interventions, exercise, pulsed ultrasound targeted to bone and whole body vibration. In this study, we attempted to mitigate paralysis-induced bone loss by applying focused ultrasound to the midbelly of a paralyzed muscle. We employed a mouse model of disuse that uses onabotulinumtoxinA-induced paralysis, which causes rapid bone loss in 5 d. A focused 2 MHz transducer applied pulsed exposures with pulse repetition frequency mimicking that of motor neuron firing during walking (80 Hz), standing (20 Hz), or the standard pulsed ultrasound frequency used in fracture healing (1 kHz). Exposures were applied daily to calf muscle for 4 consecutive d. Trabecular bone changes were characterized using micro-computed tomography. Our results indicated that application of certain focused pulsed ultrasound parameters was able to mitigate some of the paralysis-induced bone loss.

Cortical bone mechanical properties are altered in an animal model of progressive chronic kidney disease

Chronic kidney disease (CKD), which leads tocortical bone loss and increasedporosity,increases therisk of fracture. Animal models have confirmed that these changes compromise whole bone mechanical properties. Estimates from whole bone testing suggest that material properties are negatively affected, though tissue-level assessmentshavenot been conducted. Therefore, the goal of the present study was to examine changes in cortical bone at different length scales using a rat model with theprogressive development of CKD. At 30 weeks of age (∼75% reduction in kidney function), skeletally mature male Cy/+ rats were compared to their normal littermates. Cortical bone material propertieswere assessed with reference point indentation (RPI), atomic force microscopy (AFM), Raman spectroscopy,and high performance liquid chromatography (HPLC). Bones from animals with CKD had higher (+18%) indentation distance increase and first cycle energy dissipation (+8%) as measured by RPI.AFM indentation revealed a broader distribution of elastic modulus values in CKD animals witha greater proportion of both higher and lower modulus values compared to normal controls. Yet, tissue composition, collagen morphology, and collagen cross-linking fail to account for these differences. Though the specific skeletal tissue alterations responsible for these mechanical differences remain unclear, these results indicate that cortical bone material properties are altered in these animals and may contribute to the increased fracture risk associated with CKD.

A study to evaluate the cause of bone demineralization in gynecological cancer survivors

BACKGROUND

An association between treatment for gynecological cancers and risk of osteoporosis has never been formally evaluated. Women treated for these cancers are now living longer than ever before, and prevention of treatment-induced morbidities is important. We aimed to distinguish, in gynecological cancer survivors, whether cancer therapy has additional detrimental effects on bone health above those attributable to hormone withdrawal.

METHODS

We performed a retrospective cross-sectional analysis of dual energy x-ray absorptiometry (DEXA) scan results from 105 women; 64 had undergone bilateral salpingo-oophorectomy (BSO) followed by chemotherapy or radiotherapy for gynecological malignancies, and 41 age-matched women had undergone BSO for benign etiologies. All were premenopausal prior to surgery.

RESULTS

The median age at DEXA scan for the cancer group was 42 years, and 66% had received hormonal replacement therapy (HRT) following their cancer treatment. For the benign group, the median age was 40 years, and 87% had received HRT. Thirty-nine percent of cancer survivors had abnormal DEXA scan results compared to 15% of the control group, with the majority demonstrating osteopenia. The mean lumbar spine and femoral neck bone mineral densities (BMDs) were significantly lower in cancer patients. A history of gynecological cancer treatment was associated with significantly lower BMD in a multivariate logistic regression.

CONCLUSIONS

Women treated for gynecological malignancies with surgery and adjuvant chemotherapy have significantly lower BMDs than age-matched women who have undergone oophorectomy for noncancer indications. Prospective evaluation of BMD in gynecological cancer patients is recommended to facilitate interventions that will reduce the risk of subsequent fragility fractures.

[Mid-term effectiveness of total hip arthroplasty with collum femoris preserving prosthesis]

OBJECTIVE

To discuss the clinical application of total hip arthroplasty (THA) with collum femoris preserving (CFP) prosthesis and to analyze the mid-term effectiveness.

METHODS

Between January 2004 and February 2007, 45 patients (48 hips) underwent THA with CFP prosthesis. There were 29 males (31 hips) and 16 females (17 hips) with an average age of 48.8 years (range, 38-60 years), including 20 left hips, 22 right hips, and 3 bilateral hips. The causes of hip replacement were osteoarthritis (20 cases), avascular necrosis of femoral head (13 cases), dysplasia (4 cases), rheumatoid arthritis (3 cases), posttraumatic osteoarthritis (2 cases), ankylosing spondylitis (2 cases), and Perths disease (1 case). The average disease duration was 6.1 years (range, 2-13 years). Harris scores, visual analogue scale (VAS) score, and the hip range of motion (ROM) were recorded at pre- and post-operation. The X-ray films were taken at pre- and post-operation to observe the position, loosening of the prosthesis, and ectopic ossification. The gait of patients were also evaluated during follow-up. Short-form 36 health survey scale (SF-36) was used to evaluate the life quality of patients.

RESULTS

All 45 patients were followed up 5-8 years with an average of 6.4 years. All the incisions healed by first intention. No infection, hip dislocation, nerve injury, or deep vein thrombosis occurred. Six cleavage fractures (13.3%) of the lateral femoral diaphysis at the distal prosthesis occurred during operation, which healed at 8 months postoperatively without any treatment. Mild ectopic ossification occurred in 4 patients (8.9%) who had no discomfort. Five patients (11.1%) had bone mineral density loss in the region of the proximal femur. The survival rates of the cups and stems were all 100% at last follow-up. The results of Harris score, VAS score, and ROM of the hip joint at 1 year postoperatively and last follow-up were significantly better than preoperative ones (P < 0.05). No significant difference was found in VAS score and ROM of the hip joint between at 1 year postoperatively and at last follow-up (P > 0.05) except the Harris score (P < 0.05). According to Harris functional assessment at last follow-up, the results were excellent in 31 hips, good in 11 hips, and fair in 6 hips with an excellent and good rate of 87.5%. The physiological role, body pain, and total health scores were significantly lower than the reference value of urban men from Sichuan province (P < 0.05), but no significant difference was found in the other scores of the SF-36 when compared with the reference value (P > 0.05).

CONCLUSION

THA with CFP prosthesis is a good option for the young patient with complete collum femoris and without osteoporosis, and can achieve good mid-term effectiveness.

Vitamin D, parathyroid hormone, and bone mineral density status in kidney transplant recipients

INTRODUCTION

Bone disease and bone fractures are common among kidney transplant recipients. The aim of this study was to investigate the prevalence of vitamin D deficiency, hyperparathyroidism, and osteoporosis kidney transplant patients.

MATERIALS AND METHODS

A total of 113 kidney transplant recipients (58 women and 55 men) were selected consecutively from the transplant clinic between January and April 2010. A serum sample from each patient was analyzed for creatinine, calcium, phosphorus, 25-hydroxyvitamin D, and intact parathyroid hormone levels. Bone mineral density was measured by the dual energy x-ray absorptiometry method and classified according to the classification of the World Health Organization. Risk factors of bone mineral density outcomes were evaluated in univariable and multivariable analyses.

RESULTS

Forty-five percent of the patients had vitamin D deficiency and 76.2% had hyperparathyroidism. There was a significant correlation between vitamin D deficiency and high serum parathyroid hormone (P = .04) and serum creatinine levels (P = .001). However, there were no significant associations of serum calcium and phosphorus with vitamin D or parathyroid hormone levels. The osteoporosis and osteopenia were reported in 12.4% and 52.2% of the recipients in the lumbar spine and 45.1% and 36.3% of the patients in the femoral neck, respectively. Multivariable analyses showed that there were significant correlations between patients' age and body mass index and femoral neck osteoporosis. Risk factors for lumbar spine osteoporosis were end-stage renal disease duration, serum calcium, and body mass index.

CONCLUSIONS

Vitamin D deficiency, hyperparathyroidism, and osteoporosis are very common in our kidney transplant recipients. Early diagnosis and treatment of these abnormalities should be included in the posttransplant follow-up of patients in order to prevent severe bone diseases and bone fractures.

Bone density and cortical structure after pediatric renal transplantation

The impact of renal transplantation on trabecular and cortical bone mineral density (BMD) and cortical structure is unknown. We obtained quantitative computed tomography scans of the tibia in pediatric renal transplant recipients at transplantation and 3, 6, and 12 months; 58 recipients completed at least two visits. We used more than 700 reference participants to generate Z-scores for trabecular BMD, cortical BMD, section modulus (a summary measure of cortical dimensions and strength), and muscle and fat area. At baseline, compared with reference participants, renal transplant recipients had significantly lower mean section modulus and muscle area; trabecular BMD was significantly greater than reference participants only in transplant recipients younger than 13 years. After transplantation, trabecular BMD decreased significantly in association with greater glucocorticoid exposure. Cortical BMD increased significantly in association with greater glucocorticoid exposure and greater decreases in parathyroid hormone levels. Muscle and fat area both increased significantly, but section modulus did not improve. At 12 months, transplantation associated with significantly lower section modulus and greater fat area compared with reference participants. Muscle area and cortical BMD did not differ significantly between transplant recipients and reference participants. Trabecular BMD was no longer significantly elevated in younger recipients and was low in older recipients. Pediatric renal transplant associated with persistent deficits in section modulus, despite recovery of muscle, and low trabecular BMD in older recipients. Future studies should determine the implications of these data on fracture risk and identify strategies to improve bone density and structure.

[Hepatic osteodystrophy in patients with liver cirrhosis]

The article presents research data of BMD in 106 patients with liver cirrhosis. The core group of examined patients presented with LC patients the etiology of alcohol--37.7% and primary biliary cirrhosis--35.8%. In 68.9% of patients with established deficits of bone mineral density, by 24.6%--at the level of osteoporosis. Was detected influence of the etiology of the disease on the frequency of osteopenia and osteoporosis containment. Was made analysis of dependence of the frequency of osteopenia, and/or osteoporosis of population risk factors, duration of disease, grade of liver failure on the Child-Pugh. A comparative assessment of the effectiveness treatment of disorders of BMD active metabolite of vitamin D3--alpha caltsidol and drugs from the group of bisphosphonates.

Low bone density is not always bisphosphonate deficiency

Low bone density is not a one-size-fits-all disorder. We need to carefully consider the diagnostic and therapeutic options before assuming that low bone density is osteoporosis.

Severe bone demineralisation is associated with higher mortality in children with cystic fibrosis

Decreased bone mineral density (BMD) is an emerging problem for clinicians who care for children with Cystic fibrosis (CF). The aim of this study was to determine prevalence and assess risk factors for reduced BMD in our adolescent population with CF. All bone densitometry scans (n=99) performed on children (n=79) with a mean age 13.6 (10-19.2) years over a 7 year period (2000-2007) were reviewed. Patient records were reviewed for correlating clinical data. Low BMD is frequently present in adults and children with variable reports (36-66%). In our study, BMD expressed as z score of L2-L4 spine was reduced in a total of 50% children with a preponderance of males. Bone demineralization was strongly associated with increasing age (p=0.03), diminished lung function (p=0.027), reduced body mass index (p=0.001) and treatment with oral corticosteroids (p=0.02).

Bone demineralization in adult thalassaemic patients: contribution of GH and IGF-I at different skeletal sites

BACKGROUND AND OBJECTIVE

GH and IGF-I exert an important role in the control of bone formation, as shown by decreased bone mineral density and increased fracture risk in adult hypopituitary patients untreated for GH deficiency (GHD). Different degrees of bone demineralization are frequently reported in patients affected by beta-thalassaemia. Considering the high prevalence of GHD recently observed by our group among adult thalassaemic patients, we elected to study the possible role of GH-IGF-I abnormalities in the pathogenesis of the osteopenia/osteoporosis of this disease.

DESIGN

Sixty-four adult thalassaemic patients (49 with thalassaemia major and 15 with thalassaemia intermedia, 23 men and 41 women, aged 31.4 +/- 6.8 years) were studied.

METHODS

Bone mineral density was assessed by dual energy X-ray absorptiometry at lumbar spine in 62 patients and at proximal femur in 58. All patients underwent GHRH (1 microg/kg as an i.v. bolus) plus arginine (0.5 g/kg as a 30-min i.v. infusion) testing. Severe GHD was defined by GH peaks < 9 microg/l, whereas partial GHD was defined by GH peaks ranging from 9 to 16.5 microg/l. Blood samples for IGF-I measurement were collected.

RESULTS

Lumbar osteoporosis and osteopenia were demonstrated in 46/62 (74.1%) and 14/62 (22.5%) patients, respectively. Femoral osteoporosis and osteopenia were documented in 22/58 (37.9%) and 32/58 (55.1%) patients, respectively. Severe GHD was demonstrated in 16/64 patients (25%), while 11 additional patients (17.1%) displayed partial GHD. IGF-I standard deviation score (SDS) was low, that is, below -1.88, in the majority (54.6%) of patients. Lumbar T-score values were not correlated with either GH peaks or IGF-I SDS values. Femoral T-score values were positively correlated with GH peaks (r = 0.38, P < 0.005) and IGF-I SDS values (r = 0.39, P < 0.005). Multiple regression analysis pointed to both GH peak and IGF-I SDS as predictors of femoral T-score. Furthermore, mean femoral T-score was significantly lower in patients with severe GHD than in those with normal GH secretion (-2.94 +/- 0.25 vs.-2.15 +/- 0.12, P < 0.01).

CONCLUSION

This study, while confirming the high prevalence of both osteopenia/osteoporosis and somatotropin-somatomedin deficiency in adult thalassaemic patients, indicates that defective GH secretion and diminished serum IGF-I levels may contribute to femoral demineralization in these patients. Further studies are worth carrying out to evaluate the efficacy of biosynthetic GH administration on bone abnormalities of GH-deficient thalassaemic adults.

[Fractures and chronic renal insufficiency]

Chronic renal insufficiency (CRI) causes important modifications in the metabolism of phosphorus and calcium, to which frequently resulting in serious disorders of the skeleton, including demineralization, reduction of the bone resistance and a higher risk of fractures. Renal osteodystrophy is the term used to describe these disorders; they are generally heterogeneous and are classified according to the state of bone turnover into secondary hyperparathyroidism, adynamic bone, and osteomalacia. The incidence of hip fractures in the patients with CRI is higher than in the general population. Hip fractures are an important cause of morbidity and mortality. The evaluation of the fracture risk in the patients with different degrees of CRI is problematic, in particular because of the difficulty in identifying fractures, especially vertebral ones. The instrumental index that best expresses the fracture risk in the general population is bone mineral density (BMD); however, the relationship between low BMD and CRI is disputed. Bone disorders in patients with CRI have in fact a multifactorial pathogenesis and low BMD is not the only risk factor for fractures. Besides densitometric evaluation, also that vertebral morphometric evaluation would be desirable in patients with CRI. The fracture risk increases progressively with the severity of chronic renal disease and it is especially high in patients with renal insufficiency in more advanced-stages CRI (creatinine clearance<15-20 mL/min). However, not only in patients with severe CRI undergoing dialysis, but also in those with milder renal disease is the risk of bone fractures high.

[Anorexia nervosa and its consequences on bone: a therapeutic challenge]

It has been estimated that osteoporosis is present in 20 to 50% of women with anorexia nervosa, with an increased fracture risk particularly at non vertebral sites. Thus, bone loss is a major clinical concern in anorexia nervosa patients, justifying systematic evaluation. However, evidence-based therapeutic options are limited.

Assessment of bone and mineral metabolism in inflammatory bowel disease: case series and review

OBJECTIVE

To determine the prevalence of low bone mass, fractures, and vitamin D deficiency and the levels of biochemical markers of mineral metabolism in patients with inflammatory bowel disease (IBD).

METHODS

Our retrospective study consisted of 30 patients with Crohn's disease (CD) and 18 patients with ulcerative colitis (UC). Dual-energy x-ray absorptiometry was performed to determine bone mineral density at the lumbar spine and hip. Serum calcium, phosphorus, parathyroid hormone, 25-hydroxyvitamin D (25-OHD), and 1,25-dihydroxyvitamin D, urinary N-telopeptide cross-linked collagen type I, and 24-hour urinary calcium levels were evaluated.

RESULTS

On the basis of Z-score definitions of low bone mass in the IBD group as a whole, 13 patients (27%) had low bone mass at the lumbar spine. Similarly, at the femoral neck, 13 patients (27%) had low bone mass. There was a higher prevalence of low bone mass in the UC group than in the CD group, consistent with a high prevalence of fractures in that group. Of all patients with IBD, 65% had a history of fractures, of which 23% were atraumatic. Deficiency of 25-OHD was high, with a prevalence of 55% in patients with UC and 83% in patients with CD. Secondary hyperparathyroidism, defined as a parathyroid hormone level >55 pg/mL in conjunction with a low or normal serum calcium and a low 25-OHD level, was present in 50% of patients with CD and only 7% of patients with UC.

CONCLUSION

Metabolic bone disease and fractures are common in IBD. The mean bone mineral density of the spine or femoral neck did not differ significantly between patients with CD and those with UC. Patients with UC had a higher prevalence of low bone mass, as defined by a Z-score of less than -2, than did patients with CD, consistent with a high prevalence of fractures in the UC group. In contrast, hyperparathyroidism attributable to vitamin D deficiency was more prevalent in patients with CD than in those with UC. This finding suggests a different etiologic mechanism of low bone mass in patients with CD.

Cancer-treatment-induced bone loss, part 1

PURPOSE

The pathophysiology, frequency, sequelae, diagnosis, and treatment of cancer-treatment-induced bone loss (CTIBL) are discussed.

SUMMARY

CTIBL is a long-term complication associated with cancer therapies that can directly or indirectly affect bone metabolism. Although CTIBL can occur in any patient receiving a cancer therapy known to cause bone loss, CTIBL is most common in patients with breast or prostate cancer who receive chemotherapy, hormone therapy, or surgical castration, as these can cause hypogonadism and induce bone loss. CTIBL causes bone fragility and an increased susceptibility to fractures; therefore, prevention, early diagnosis, and treatment of CTIBL are essential to decrease the risk of fracture. Bone loss occurs more rapidly and tends to be more severe in patients with CTIBL compared with those with normal age-related bone loss. Fractures of the hip, vertebra, and wrist are the fractures most commonly associated with bone loss. CTIBL is diagnosed by measuring bone mass using bone densitometry. Treatment of CTIBL consists of changing diet and lifestyle such as optimizing calcium and vitamin D intake, exercising, modifying behaviors known to increase the risk of CTIBL and pharmacologic therapy with hormone replacement therapy (HRT), selective estrogen-receptor modifiers (SERMs), calcitonin, or a bisphosphonate.

CONCLUSION

Early identification and treatment of CTIBL are essential to prevent fractures. Patients should be instructed to optimize calcium and vitamin D intake, exercise regularly, and modify lifestyle behaviors known to cause bone loss. Patients with CTIBL should be treated with an oral or i.v. bisphosphonate; SERMs or HRT may be an option in some patients if contraindications do not exist.

New patients: should children be treated differently?

Inflammatory bowel disease (IBD) in childhood is often diagnosed at a vulnerable time of growth and development, and is recognized as one of the most significant chronic gastrointestinal diseases to affect children. Children and adolescents with IBD are at increased risk of complications as a result of malnutrition secondary to reduced appetite, increased metabolism and decreased absorptive capacity. The most common and serious complications are growth failure, bone demineralization and impaired psychosocial development. These issues add to the complexity of childhood IBD management and it is essential that adequate medical management is in place to prevent these long-term complications. Current treatment options include 5-aminosalicylic acid, antibiotics, corticosteroids, nutritional therapy and immunomodulators used to induce and maintain remission; some are specifically employed to maintain a steroid free long-term remission. As a general rule, long-term corticosteroid use should be avoided to reduce the risk of bone demineralization and growth failure. Newer treatment options such as infliximab have been shown to be effective for inducing and prolonging remission of Crohn's disease in children and paediatric use of infliximab is likely to increase in the near future. A recent case report, involving a 15-year old boy presenting with abdominal pain and bloody diarrhoea, illustrates the difficulty in correctly diagnosing IBD in children and the need for optimizing therapy to achieve treatment success.

Bone demineralization and vertebral fractures in endogenous cortisol excess: role of disease etiology and gonadal status

INTRODUCTION

The effects of endogenous cortisol (F) excess on bone mass and vertebral fractures have still not been thoroughly investigated. The aim of this cross-sectional case-control study was to investigate factors influencing bone demineralization and vertebral fractures in different conditions of F excess, i.e. Cushing's disease and adrenal and ectopic Cushing's syndrome.

MATERIALS AND METHODS

Eighty consecutive patients and 80 controls were prospectively enrolled: 37 patients (21 females) with pituitary ACTH-secreting adenoma, 18 (14 females) with adrenocortical adenoma, 15 (11 females) with adrenal carcinoma of mixed secretion, and 10 (three females) with ectopic ACTH secretion. The groups had similar age. At diagnosis, bone mineral density (BMD) was determined by the dual-energy x-ray absorptiometry technique at the lumbar spine (L1-L4) and femoral neck; vertebral fractures were investigated by standard spinal radiographs.

RESULTS

When comparing the groups with different etiology of F excess, the patients with ectopic ACTH secretion had higher F and lower BMD values than the other subgroups. Morning F (P = 0.03) and testosterone levels (P = 0.04) correlated with lumbar BMD. Vertebral fractures were found in 61 (76%) of the patients, were multiple in 52 (85%) of the cases, and clinically evident in 32 (52%). Only multiple fractures were more frequent in patients with ectopic ACTH hypersecretion (P < 0.05). Lumbar spine BMD was the best predictor of vertebral fractures (P < 0.01). Surprisingly, amenorrheic and eumenorrheic women had similar BMD values and fracture prevalence.

CONCLUSION

A high prevalence (76%) of vertebral fracture was revealed, regardless of the etiology of the patients' hypercortisolism. The harmful effects of F excess at the spine were partly counterbalanced by the increased androgen production but were not affected by gonadal status in women.

Association between phosphate removal and markers of bone turnover in haemodialysis patients

BACKGROUND

As the main mineral reservoir, bone acts as a calcium (Ca) and phosphate buffering system. Accordingly, phosphate removal by haemodialysis (HD) might be theoretically influenced by bone turnover, as well as by the interaction of regulatory molecules, such as PTH and osteoprotegerin (OPG). The present study investigated the relationship between these variables and phosphate removal by HD.

METHODS

Blood samples for serum Ca, phosphate, bicarbonate, intact PTH, PTH (1-84), bone alkaline phosphatase, tartrate-resistant acid phosphatase 5b, OPG and receptor activator of nuclear factor-kappaB ligand (RANKL) were obtained in 28 HD patients. Phosphate removal was measured by a continuous collection of the dialysate.

RESULTS

Pre-dialysis serum phosphate concentration is the critical factor in determining dialytic phosphate removal. However, multiple regression analysis reveals that phosphate removal is better explained by a combination of factors than by phosphate concentration alone. In this model, the PTH/OPG ratio is an additional positive factor, whereas age and vitamin D treatment are negative factors. Patients with pre-HD bicarbonate higher than 20 mEq/l had higher serum phosphate and, accordingly, higher phosphate removal; of interest, these individuals also have significant differences in RANKL/OPG. Mean (SD) OPG levels were significantly higher than that in the healthy population (16.2 (12.5) pmol/l; these values correlated with age (r = 0.4, P<0.04). Mean serum RANKL (1.03 (1.02) pmol/l) was within the range of normal individuals.

CONCLUSIONS

Dialytic phosphate removal has a crucial, direct relationship with pre-HD plasma phosphate levels. However, the phenomenon of phosphate removal is more precisely explained using a more complex relationship, defined by the interaction between serum phosphate, PTH/OPG, age and vitamin D administration. Serum RANKL levels are first reported in HD patients, and are not different from the normal population.

Muscle strength is a determinant of bone mineral content in the hemiparetic upper extremity: implications for stroke rehabilitation

Individuals with stroke have a high incidence of bone fractures and approximately 30% of these fractures occur in the upper extremity. The high risk of falls and the decline in bone and muscle health make the chronic stroke population particularly prone to upper extremity fractures. This was the first study to investigate the bone mineral content (BMC), bone mineral density (BMD), and soft tissue composition of the upper extremities and their relationship to stroke-related impairments in ambulatory individuals with chronic stroke (onset >1 year). Dual-energy X-ray absorptiometry (DXA) was used to acquire total body scans on 56 (22 women) community-dwelling individuals (>or=50 years of age) with chronic stroke. BMC (g) and BMD (g/cm2), lean mass (g), and fat mass (g) for each arm were derived from the total body scans. The paretic upper extremity was evaluated for muscle strength (hand-held dynamometry), impairment of motor function (Fugl-Meyer motor assessment), spasticity (Modified Ashworth Scale), and amount of use of the paretic arm in daily activities (Motor Activity Log). Results showed that the paretic arm had significantly lower BMC (13.8%, P<0.001), BMD (4.5%, P<0.001), and lean mass (9.0%, P<0.001) but higher fat mass (6.3%, P=0.028) than the non-paretic arm. Multiple regression analysis showed that lean mass in the paretic arm, height, and muscle strength were significant predictors (R2=0.810, P<0.001) of the paretic arm BMC. Height, muscle strength, and gender were significant predictors (R2=0.822, P<0.001) of lean mass in the paretic arm. These results highlight the potential of muscle strengthening to promote bone health of the paretic arm in individuals with chronic stroke.

Reduced Loss of Hand Bone Density With Prednisolone in Early Rheumatoid Arthritis

BACKGROUND

Bone damage in rheumatoid arthritis presents as osteoporosis and joint erosions. Prednisolone has been shown to reduce the rate of hand joint destruction as seen on radiography but has not been shown to reduce the rate of hand bone loss.

METHODS

In a double-blind study comparing oral prednisolone (7.5 mg/d for 2 years) with placebo, hand bone density assessed with digital x-ray radiogrammetry was examined in 95 patients with rheumatoid arthritis with disease duration of less than 2 years.

RESULTS

The mean loss of hand bone density was less in prednisolone-treated patients compared with placebo-treated patients at the 1-year follow-up (-0.011 vs -0.022 g/cm(2)) (P = .005) and at the 2-year follow-up (-0.026 vs -0.039 g/cm(2)) (P = .03). The mean percentage group difference in loss of hand bone density was 2.8% (P = .004) at the 1-year follow-up and 3.5% (P = .01) at the 2-year follow-up. In the first year, C-reactive protein, a marker of inflammation, was strongly correlated with hand bone loss in placebo-treated patients but not in prednisolone-treated patients, suggesting that prednisolone breaks the link between bone loss and inflammation.

CONCLUSIONS

To our knowledge, this is the first double-blind randomized study to show that disease-related loss of hand bone density in rheumatoid arthritis can be decelerated by prednisolone. This finding suggests that the deleterious effect of prednisolone on bone may be counteracted by its anti-inflammatory effect.

Vitamin E provides protection for bone in mature hindlimb unloaded male rats

The deleterious effects of skeletal unloading on bone mass and strength may, in part, result from increased production of oxygen-derived free radicals and proinflammatory cytokines. This study was designed to evaluate the ability of vitamin E (alpha-tocopherol), a free-radical scavenger with antiinflammatory properties, to protect against bone loss caused by skeletal unloading in mature male Sprague-Dawley rats. A 2 x 3 factorial design was used with either hindlimb unloading (HU) or normal loading (ambulatory; AMB), and low-dose (LD; 15 IU/kg diet), adequate-dose (AD; 75 IU/kg diet), or high-dose (HD; 500 IU/kg diet) vitamin E (DL-alpha-tocopherol acetate). To optimize the effects of vitamin E on bone, dietary treatments were initiated 9 weeks prior to unloading and continued during the 4-week unloading period, at which time animals were euthanized and blood and tissue samples were collected. Serum vitamin E was dose-dependently increased, confirming the vitamin E status of animals. The HD treatment improved oxidation parameters, as indicated by elevated serum ferric-reducing ability and a trend toward reducing tissue lipid peroxidation. Histomorphometric analysis of the distal femur revealed significant reductions in trabecular thickness (TbTh), double-labeled surface (dLS/BS), and rate of bone formation to bone volume (BFR/BV) due by HU. AMB animals on the HD diet and HU animals on the LD diet had reduced bone surface normalized to tissue volume (BS/TV) and trabecular number (TbN); however, the HD vitamin E protected against these changes in the HU animals. Our findings suggest that vitamin E supplementation provides modest bone protective effects during skeletal unloading.

The next small step

The microgravity experienced in space missions has serious effects on human physiology. How to get a crew to Mars in an optimal state for landing and exploration remains a matter of some debate

Modern analysis of bone loss mechanisms in microgravity

A summary of results of investigations by the author and a brief review of some literature data on human bone tissue deprived of mechanical loading (spaceflight, hypokinesia) is given. The direction and markedness of changes in bone mass--the bone mineral density and the bone mineral content--in different skeletal segments depend on their position relative to the gravity vector. A theoretically expected bone mass reduction was revealed in the trabecular structures of the bones of the lower part of the skeleton (local osteopenia). In the upper part of the skeleton, an increase in the bone mineral content is observed, which is considered as a secondary response and is due to redistribution of body fluids cephalad. The main cause of osteopenia is mechanical unloading. Arguments are presented that osteocyte osteolysis, delayed osteoblast histogenesis, and osteoclast resorption provoked by rearrangement in the hierarchy of the systems of fluid volume and ion regulation, and the endocrine control of calcium homeostasis are the main mechanisms of osteopenia.

[Current views on the etiopathogenesis of idiopathic osteoporosis and osteopenia in the developmental period]

The paper presents current literature review on the clinical features and possible etiopathogenetic factors in idiopathic osteoporosis and osteopenia in children and adolescents. Genetic and environmental factors determining bone mass growth are included. The effect of cytokines and hormones in the regulation of bone remodelling has been discussed in detail. Most recent studies have demonstrated that cytokines are involved in bone formation and resorption by their direct influence on the activity of osteoclasts and osteoblasts. In this way they affect the state of dynamic balance between the process of bone formation and resorption, and thus the mineralization of the skeleton.

Bone density loss after spinal cord injury: elite paraplegic basketball players vs. paraplegic sedentary persons

OBJECTIVE

To compare the bone mineral density of elite paraplegic basketball players with the values obtained from their paraplegic sedentary counterparts.

DESIGN

A total of 17 male paraplegic basketball players and 17 male paraplegic sedentary persons were included in the study. Bone mineral densities of the distal third of radius of the dominant arm, L2-L4 spine, and trochanters, Ward's triangles, and the femoral necks of both hips were measured.

RESULTS

The densities of trochanters, Ward's triangles, and the femoral necks were found to be decreased in both groups, with no significant difference between them. The densities of lumbar and radial regions were found to be increased in both groups. Radial density was significantly higher in paraplegic basketball players than in paraplegic sedentary patients, whereas the groups were not significantly different for lumbar density.

CONCLUSIONS

Wheelchair basketball in spinal cord-injured patients was associated with greater bone density in distal radius compared with sedentary paraplegics. However, it was not associated with greater density below the injury level.

Bone loss in the contralateral asymptomatic hand in patients with complex regional pain syndrome type 1

Regional osteoporosis was seen radiographically in clinically affected areas in patients with complex regional pain syndrome type 1 (CRPS1). The aim of the this study was to investigate whether bone loss developed in the contralateral hand in patients with unilateral CRPS1 of the hand. Thirty-two patients with CRPS1 of the hand were included in this study. Bone mineral density was measured in the left proximal femur and both ultradistal radiuses, using dual-energy X-ray absorptiometry. The subjects were classified as grades 1 to 3 according to the T-score of both ultradistal radiuses (densitometric grades): grade 1, both radiuses were normal; grade 2, bone loss was determined only in the affected radius; and grade 3, there was bone loss in both radiuses. Twenty (62.5%) patients had bone loss in the affected hand; 11 patients (34.4%) had bone loss only on the affected side and 9 patients (28.1%) had bone loss on both sides. The mean duration of the period between the diagnosis of the injury and the measurement of bone density was 1.9 +/- 0.6 months in patients with grade 1, 3.1 +/- 1.0 months in patients with grade 2, and 5.5 +/- 2.2 months in patients with grade 3. The Spearman test showed a significant correlation between the period of injury and the densitometric grade ( R = 0.774; P = 0.0001). In conclusion, the current study of patients with CRPS1, showed that the bone loss in the asymptomatic contralateral hand developed at a later stage than that in the affected hand. This bone loss was less frequent and of a lower degree in the asymptomatic contralateral hand than in the affected hand. The bone loss in the asymptomatic contralateral hand could be explained by the loss of sympathetic tone in CRPS1 and contralateral sympathetic innervation.

A randomized controlled trial of calcium with vitamin D, alone or in combination with intravenous pamidronate, for the treatment of low bone mineral density associated with Crohn's disease

BACKGROUND

Osteoporosis is a common complication of Crohn's disease.

AIM

To study the effect on the bone mineral density of a bisphosphonate (pamidronate) given intravenously, in combination with oral calcium and vitamin D supplements, compared with oral calcium and vitamin D supplements alone.

METHODS

Seventy-four patients with Crohn's disease and low bone mineral density at the lumbar spine and/or hip were randomized to receive either a daily dose of 500 mg of calcium with 400 IU of vitamin D alone or in combination with four three-monthly infusions of 30 mg of intravenous pamidronate over the course of 12 months. The main outcome measure was the change in bone mineral density at the lumbar spine and hip, measured by dual X-ray absorptiometry, at baseline and 12 months.

RESULTS

Both groups gained bone mineral density at the lumbar spine and hip after 12 months. There were significant (P < 0.05) changes in the pamidronate group, with gains of + 2.6%[95% confidence interval (CI), 1.4-3.0] at the spine and + 1.6% (95% CI, 0.6-2.5) at the hip, compared with gains of + 1.6% (95% CI, - 0.1-3.2) and + 0.9% (95% CI, - 0.4-2.1) at the spine and hip, respectively, in the group taking vitamin D and calcium supplements alone.

CONCLUSIONS

In patients with Crohn's disease and low bone mineral density, intravenous pamidronate significantly increases the bone mineral density at the lumbar spine and hip.

[Changes in bone density in hemodialysed women treated with transdermal hormone replacement therapy]

OBJECTIVES

Renal insufficiency in women can cause menstrual disturbances and changes of hormonal profile leading to the decrease of bone mass density. Drug administration during dialysis also influences the bone density and increases the risk of osteoporosis. The aim of the study is to assess the effect of transdermal hormonal replacement therapy (HRT) in hemodialysed patients with secondary amenorrhea on bone density.

MATERIAL AND METHODS

10 women aged from 22 to 45 years old were enrolled in the study. They received 17 beta-estradiol and norethisterone acetate in patches during 12 cycles. Densitometer of lumbar spine and serum estradiol concentration were measured before and after 12 cycles of therapy.

RESULTS

The recurrence of regular vaginal bleeding, the increase of estradiol levels and bone mass density rate about 6% were observed.

CONCLUSIONS

Transdermal hormonal replacement therapy in hemodialysed women with secondary amenorrhea revealed the efficacy of the treatment and prevention from osteoporosis.

Periimplant Bone Healing under Experimental Hepatic Osteodystrophy Induced by a Choline-Deficient Diet: A Histomorphometric Study in Rats

BACKGROUND

Osseointegration and success of an implant involve the interaction of local and systemic factors such as bone metabolic diseases.

PURPOSE

The purpose of this study was to evaluate the effect of experimental hepatic osteodystrophy induced by a choline-deficient diet on periimplant bone healing.

MATERIALS AND METHODS

Laminar titanium implants were placed in the tibias of five groups of Wistar rats: those with a (1). controlled diet for 15 days; (2). choline-deficient diet for 15 days; (3). controlled diet for 30 days; (4). choline-deficient diet for 30 days; (5). choline-deficient diet for 15 days and a controlled diet for 15 days (refeeding). Body weight and food intake, hematocrit, and hemoglobinemia were evaluated. The animals were killed at 15 or 30 days post implantation. The liver, kidneys, and tibias were resected and fixed in 20% formalin solution. The tibias were radiographed and processed for histomorphometric evaluation of the periimplant bone area.

RESULTS

Histologic studies revealed steatosis in the liver but no alterations in the kidneys. Rats fed a choline-deficient diet showed periimplant bone healing with marked qualitative and quantitative alterations. The periimplant bone area was 28% and 75% lower in experimental animals than in controls at 15 and 30 days, respectively.

CONCLUSIONS

Liver alterations caused by a choline-deficient diet alter periimplant osteogenesis qualitatively and quantitatively.

[Changes of osteocalcin in bone and bone marrow in tail suspended rats]

OBJECTIVE

To study osteocalcin [correction of osteocakin] (OC) changes in bone and marrow and calcium deposition in bone and cartilage under simulated weightlessness.

METHOD

Twenty SD rats were randomly divided into 14 d and 28 d tail suspension group and 2 corresponding control groups. Histological samples were in situ hybridized and trichrome stained.

RESULT

OC expression of bone and marrow of rats were lower in tail suspended rats than that in the control (P<0.05). OC expression in 14 d tail suspended rats were higher than that in 28 d tail suspended group (P<0.05). Mineralization was inhibited, and demineralization of femur [correction of furmer] and cartilage mineralized matrix was prominent. Demineralization was more prominent in 28 d group.

CONCLUSION

OC levels in bone and marrow of rats were lower after tail suspension. Calcium deposition was inhibited in bone and cartilage. Demineralization was prominent after long term hindlimb unloading.

Model of the mechanism of Ca loss by bones under microgravity and earth conditions

A comparative characterization of crystal structure, morphology, sizes, and orientation in Ca phosphate precipitation from aqueous solutions, the mineral phase in bones, and mineral deposits on cardiac valves has been performed by high-resolution transmission electron microscopy to model possible mechanisms of Ca loss by bones. Physiological changes occurring in organisms can lead to deep perturbations of the natural calcium phosphate supersaturation and its local distribution, which in turn influences the phase composition, morphology, and organization of the mineral phase. Formation of crystals with larger size or of two distinct phases instead of the single hydroxyapatite one can result in the deterioration of the Ca balance in bone and tissue destruction as well as the possible misorientation (or spread of orientation) between HAP crystals newly formed in the bone.

Changes in serum 1,25-dihydroxyvitamin D3 and mRNAs for osteocalcin and alkaline phosphatase in femur unloaded by tail suspension in rats

To elucidate the mechanism involved in the development of disuse atrophy of bone by skeletal unloading, changes in osteocalcin and alkaline phosphatase mRNAs, markers for bone formation, were studied in the hind limb bones of tail-suspended rats. Tail suspension for 8 and 14 days resulted in a significant decrease in osteocalcin mRNA in the femur when compared with age-matched non-suspended controls. Serum 1,25-dihydroxyvitamin D3 decreased to 60% of the control level after 8 days of skeletal unloading but regained almost normal levels over the next 7 days. Since it is known that vitamin D3 up regulates and glucocorticoid down regulates transcription of the osteocalcin gene, the endocrine response evoked by tail suspension may have aggravated the disuse atrophy caused by skeletal unloading in this study.

Loss of bone mineral of the hip and proximal tibia following rupture of the Achilles tendon

In a prospective uncontrolled study 12 patients suffering from a rupture of the Achilles tendon treated operatively with surgical repair and post-operative immobilization in a short plaster cast for 6 weeks had bilateral measurements of bone mineral content (BMC) of the proximal tibia and bone mineral density (BMD) of the femoral neck and greater trochanter. The measurements were performed by dual energy X-ray absorptiometry (DEXA) and scans were performed post-operatively within 7 days after the operation and with follow up after 6 weeks, 3, 6, and 12 months. In the operated legs, BMC of the proximal tibia showed a progressive decrease reaching a total bone loss of 6.4% (95%-CL: -10.6%; -2.3%) 1 year after the injury. Bone mineral density at the hip of the operated legs also decreased significantly and 1 year after the injury BMD was 2.5% (95%-CL: -5.5%; 0.5%) and 6.8% (95%-CL: -9.8%; -3.7%) below the initial value in, respectively, the femoral neck and greater trochanter. Patients with a previous Achilles tendon rupture must be considered to be some years ahead in their natural osteoporotic process of the bones of the affected legs, and an increased risk of osteoporotic fractures must be considered not to be only theoretical.

The physical price of a ticket into space

As a direct consequence of exposure to microgravity astronauts experience a number of physiological changes, which can have serious medical implications when they return to Earth. Most immediate and significant are the head-ward shift of body fluids and the removal of gravitational loading from bone and muscles, which lead to progressive changes in the cardiovascular and musculoskeletal systems. Cardiovascular adaptations result in an increased incidence of orthostatic intolerance (fainting) post-flight, decreased cardiac output and reduced exercise capacity. Changes in the musculoskeletal system contribute significantly to the impaired functions experienced in the post-flight period. The underlying factor producing these changes is the absence of gravity. Countermeasures, therefore, are designed primarily to simulate Earth-like movements, stresses and system interactions. Exercise is one approach that has received wide operational use and acceptance in both the US and Russian space programmes, and has enabled humans to stay relatively healthy in space for well over a year. Although it remains the most effective countermeasure currently available, significant physiological degradation still occurs. The development of other countermeasures will therefore be necessary for longer duration missions, such as the human exploration of Mars.

Calcium metabolism under stress and in repose

Derangement of calcium metabolism, although perhaps not as dramatic as that of the cardiovascular or vestibular systems, constitutes one of the major threats to the health of participants in exploration of space. On the basis of studies in immobilized subjects, the clinical disorders most likely to be encountered during prolonged space flight are primarily the consequence of an imbalance between bone formation and resorption (favoring the latter): (1) loss of skeletal mass, leading to osteoporosis; (ii) hypercalcemia; and (iii) hyper-calciuria, with the attendant risk of nephrolithiasis. By itself, loss of skeletal mass would not be expected to pose an in-flight hazard, but hypercalcemia or nephrolithiasis could jeopardize lives or mission success. Such data as are available from in-flight studies tend to support the use of immobilization as a terrestrial model for alterations in calcium metabolism during space flight. A variety of prophylactic measures have been attempted with this model in an effort to modify the observed disorders. Although there is some evidence that hypercalcemia and hypercalciuria can be reduced or prevented, negative calcium balance has not been completely reversed. Perhaps the most successful prophylactic measure utilized to date has been dietary supplementation of both calcium and inorganic phosphate. With the wide variety of excellent study tools which are currently available for application to this field, significantly increased efforts are clearly required both to define the basic mechanism of immobilization-induced skeletal losses and to devise new prophylactic or therapeutic approaches.

[Bone metabolism in adolescent girls with short course of anorexia nervosa]

OBJECTIVE

The objective of this study was to determine the prevalence of bone mass reduction and determine its causes in young girls with short course of anorexia nervosa (AN).

METHOD

Bone mineral density (BMD)of lumber spine by dual energy x-ray absorptiometry, total alkaline phosphatase (TAP), bone-Gla protein (BGP), urine deoxypyridinoline (DPYR), DPYR, urine calcium, sex hormones were measured in 24 in-patient girls with diagnosed AN and 20 healthy volunteers.

RESULTS

Girls with AN had a significantly lower BMD than their age-matched controls. Osteopenia and osteoporosis were present even in the group with AN diagnosed within the previous 12 months. BMD correlated negatively with minimal BMI and positively with the duration of regular menses before AN onset. BGP and DPYR were significantly lower in AN patient than in the control group. Values of urine calcium of AN patients were comparable with control group, but showed a positive correlation with disease duration.

DISCUSSION

Reduction of bone mineral density is present in girls with short course of AN. Nutritional status is the most important predictor of BMD. Bone metabolism is decreased in the early stages of the disease.

[Osteoporosis and demineralization: a semantic confusion]

Osteoporosis is the most frequent demineralizing disease. However, when a demineralized vertebra is identified, other diseases must be ruled out in the course of diagnosis. Through three clinical cases, we analyze pitfalls that have delayed the diagnosis of one rare, but unfortunately lethal, aetiology: multiple myeloma.

Bone mineral density in adolescent girls with anorexia nervosa--a cross-sectional study

The total body and lumbar spine bone mineral density (BMD) were measured in order to determine the prevalence and possible risk factors of decreased BMD in anorexia nervosa (AN).

SUBJECTS

Sixty-one in-patient girls with DSM III-R AN: age 14.7+/-2.16 years; duration of AN 12.9+/-15.1 months; percentage of ideal body weight 70+/-8.7%; body mass index score -1.62+/-0.79.

METHOD

Total body (in 61 patients) and lumbar spine BMD (in 43 patients), content of lean and fat tissue mass were measured by DXA during the first month of treatment.

RESULTS

Low total body BMD was found in 23.7% and low lumbar spine BMD in 36.6% of patients. There was a negative correlation between BMD and age, age of menarche, degree of undernourishment, duration of AN and amenorrhea. A step-wise linear regression analysis revealed that age of menarche was the most important factor related to BMD in this group.