Effects of ospemifene on breast tissue morphology and proliferation: a comparative study versus other selective estrogen receptor modulators in ovariectomized rats

Ospemifene is a tissue-selective estrogen agonist/antagonist that was recently approved for the treatment of dyspareunia associated with vulvar and vaginal atrophy, which occurs in up to approximately 50% of postmenopausal women. The current analyses were conducted to determine whether ospemifene exhibits estrogenic activity in the mammary glands of ovariectomized rats and to compare potential estrogenic activity with selective estrogen receptor modulators (tamoxifen, raloxifene, and toremifene). Three separate studies with differing durations (6, 9, and 28 days) were conducted using similar procedures in ovariectomized Sprague-Dawley rats. Estradiol treatment and sham-treated ovariectomized rats were used as positive and negative controls, respectively. Cell proliferation was examined using labeled 5-bromo-2-deoxyuridine; cytoplasmic prolactin was characterized with antibody staining. The morphology of the mammary gland was studied by histological staining of sections from the right fourth mammary glands, and the excised gland from the left side was used for counting the lobulus number. Neither ospemifene nor selective estrogen receptor modulators substantially induced 5-bromo-2-deoxyuridine staining, altered the morphology of the mammary glands, or changed prolactin immunostaining in ovariectomized rats compared with the ovariectomized controls. With the exception of toremifene, the selective estrogen receptor modulators did not cause a substantial induction in mammary gland lobuli. Estradiol had effects opposite to those of the selective estrogen receptor modulators in these studies. Ospemifene exhibited no substantial estrogenic activity in the mammary gland of ovariectomized rats. Activity in the mammary gland of ovariectomized rats with ospemifene was comparable to raloxifene and tamoxifen.

Effects of the selective estrogen receptor modulator ospemifene on bone in rats

Ospemifene is a non-estrogen agent that exerts tissue-specific estrogen agonistic and weak antagonistic effects (i. e., is a selective estrogen receptor modulator [SERM]). The effects of various once-daily oral doses of ospemifene on bone are examined across 3 studies for 4 or 52 weeks after surgery in the ovariectomized (OVX) rat model of postmenopausal bone loss. Ospemifene treatment reduced the loss of bone mineral content and density observed in untreated OVX rats, significantly increased distal femur bone mineral content at 51 weeks at 25 mg/kg dose compared with untreated OVX rats (p<0.01), and significantly increased trabecular bone mineral density of the distal femur and proximal tibia with 1, 5, or 25 mg/kg doses after 52 weeks. Ospemifene 5 and 25 mg/kg preserved distal femur trabecular structure; trabecular number was significantly increased, whereas trabecular separation and eroded surface values were significantly decreased (all p<0.01). Structural changes associated with ospemifene were accompanied by increased mechanical strength of femurs and 4th lumbar vertebra compared with untreated OVX rats. Ospemifene 10 mg/kg prevented OVX-induced bone loss; trabecular bone volume of distal femurs was increased after 4 weeks. Further, histomorphometric measures revealed decreased bone resorption after 4 weeks of ospemifene treatment, with effects similar to other SERMs (raloxifene and droloxifene). Ospemifene 3 and 10 mg/kg significantly inhibited OVX-induced increases in osteoclast number, and doses ≥0.3 mg/kg dose-dependently reversed the OVX-induced increase in the double-labeled volume:bone volume ratio. These results demonstrate antiresorptive, selective agonist effects of ospemifene on bone that appear similar to raloxifene in this in vivo animal model of estrogen deficiency.

Total and carboxylated osteocalcin associate with insulin levels in young adults born with normal or very low birth weight

OBJECTIVE

Osteocalcin (OC), a bone-derived protein, has been implicated in the regulation of glucose and energy metabolism. Young adults born with very low birth weight (VLBW) have altered glucose regulation and lower bone mineral density (BMD) compared with those born at term. The aim of this study was to explore the association between bone and glucose metabolism in healthy young adults born prematurely or at term.

METHODS

The cohort of this cross-sectional study comprised 332 non-diabetic young adults (age 18 to 27 years) born either preterm with VLBW (n = 163) or at term (n = 169). OC, carboxylated osteocalcin (cOC) and markers of glucose metabolism were measured at fasting and after a 75-g oral glucose tolerance test (OGTT).

RESULTS

VLBW adults were shorter, had lower BMD (p<0.001) and higher fasting OC (p = 0.027) and cOC (p = 0.005) than term-born subjects. They also had higher 2-hour insulin (p = 0.001) and glucose (p = 0.037) concentrations. OGTT induced a significant reduction in OC (p<0.001), similar in both groups. OC reduction was not associated with OGTT-induced increases in insulin (p = 0.54). However, fasting total OC and cOC correlated negatively with fasting insulin after adjustment for age, gender, BMD and VLBW status (r = -0.182, p = 0.009 and r = -0.283, p<0.001, respectively).

CONCLUSION

Adults born with VLBW have higher OC and cOC than their peers born at term. This may in part reflect the mechanisms that underlie their lower BMD and decreased insulin sensitivity. Serum OC appears to be negatively associated with long-term glucose regulation whereas acute changes during OGTT may be mediated via other mechanisms.

Neurofibromatosis 1-related osteopenia often progresses to osteoporosis in 12 years

The current study is based on our earlier investigation carried out in 1999, where bone mineral density (BMD) of 35 neurofibromatosis type 1 (NF1) patients was measured and osteoporosis was shown to be common in NF1. The findings have been confirmed by a number of later publications. The purpose of the current longitudinal study was to assess the bone health of these 35 NF1 patients 12 years after the initial study. A total of 28 patients were reached, and BMD of 19 patients was subsequently remeasured. Fracture history of 28/35 NF1 patients who were reached was verified from the medical records. Six NF1 patients had osteoporosis in 1999, and three of them had an osteoporotic fracture between 1999 and 2011, showing an increased fracture risk compared to NF1 patients without osteoporosis. BMD of 19 patients was remeasured in 2011, and four patients who had osteopenia in 1999 had osteoporosis in 2011. The decrease in BMD was not explained by changes in smoking habits, physical activity, sunlight exposure, body mass index, or laboratory parameters, even though secondary hyperparathyroidism was common. Osteoporosis was found in 2011 in patients aged 37 years or older, both men and women. The results showed that NF1-related osteopenia often progresses to osteoporosis since BMD decreases with aging even in young patients. Even though our sample size was 19 patients, we recommend follow-up of NF1 patients with osteopenia and consideration of prophylactic measures to prevent osteoporosis and associated fracture risk.

Osteoclasts derived from patients with neurofibromatosis 1 (NF1) display insensitivity to bisphosphonates in vitro

A total of 20 patients with neurofibromatosis 1 (NF1) were screened for NF1-related osteoporosis, and blood samples were collected for isolation of peripheral blood osteoclast progenitors. Patients with NF1 had higher levels of serum bone turnover markers (CTX and PINP) compared to controls. In addition, persons with high bone resorption in vitro on average had high levels of serum CTX. Of the 20 patients with NF1, 15 had low bone mineral density (osteopenia/osteoporosis), but these 15 patients did not have marked risk factors for low bone mineral density. Thus, we recommend screening for osteoporosis to all adult patients with NF1. Our aim was also to characterize the effects of bisphosphonates on NF1 osteoclasts in vitro. NF1 osteoclasts and osteoclasts from healthy controls in vitro were treated with zoledronic acid, alendronate and clodronate. These bisphosphonates caused a marked reduction in the number of normal control osteoclasts in vitro, while only a slight change was observed in the number of NF1 osteoclasts. Ras-inhibitor FTS counteracted this NF1-related insensitivity to zoledronic acid, suggesting that Ras may play a role in this phenomenon.

Panel discussion does not improve reliability of peer review for medical research grant proposals

OBJECTIVE

Peer review is the gold standard for evaluating scientific quality. Compared with studies on inter-reviewer variability, research on panel evaluation is scarce. To appraise the reliability of panel evaluations in grant review, we compared scores by two expert panels reviewing the same grant proposals. Our main interest was to evaluate whether panel discussion improves reliability.

METHODS

Thirty reviewers were randomly allocated to one of the two panels. Sixty-five grant proposals in the fields of clinical medicine and epidemiology were reviewed by both panels. All reviewers received 5-12 proposals. Each proposal was evaluated by two reviewers, using a six-point scale. The reliability of reviewer and panel scores was evaluated using Cohen's kappa with linear weighting. In addition, reliability was also evaluated for the panel mean scores (mean of reviewer scores was used as panel score).

RESULTS

The proportion of large differences (at least two points) was 40% for reviewers in panel A, 36% for reviewers in panel B, 26% for the panel discussion scores, and 14% when the means of the two reviewer scores were used. The kappa for panel score after discussion was 0.23 (95% confidence interval: 0.08, 0.39). By using the mean of the reviewer scores, the panel coefficient was similarly 0.23 (0.00, 0.46).

CONCLUSION

The reliability between panel scores was higher than between reviewer scores. The similar interpanel reliability, when using the final panel score or the mean value of reviewer scores, indicates that panel discussions per se did not improve the reliability of the evaluation.

Osteoclasts in neurofibromatosis type 1 display enhanced resorption capacity, aberrant morphology, and resistance to serum deprivation

Neurofibromatosis 1 syndrome (NF1) presents with skeletal involvement suggesting that altered bone dynamics is associated with NF1. Histological analysis of three cases of NF1-related pseudarthrosis revealed numerous osteoclasts in contact with adjacent bone, and within the pseudarthrosis tissue itself. These findings prompted us to evaluate the differentiation and resorption capacity of NF1-osteoclast like cells (OLCs) in vitro. Osteoclast progenitors were isolated from peripheral blood of 17 patients with NF1 and allowed to differentiate into OLCs on bone slices. The following differences were found between NF1 and control samples: samples from NF1 patients resulted in a higher number of resorbing OLCs; NF1 OLCs were larger in size; their nuclei were more numerous; actin rings were more frequent; and the resorption pits in NF1 samples were more numerous and larger. Bone resorption markers revealed that the resorption activity in NF1 OLC cultures was approximately two times higher than in controls. Following deprivation from serum, the number of NF1 OLCs remained essentially the same during 24h, whereas the number of control OLCs was dramatically reduced during the same time. Three patients had NF1-related lytic bone lesions, and their in vitro results differed from those of other patients. Our results demonstrate that OLCs derived from blood of patients with NF1 display elevated resorption activity under conditions isolated from microenvironment operative in vivo. Thus, increased osteoclast activity may be a phenotypic property of the NF1 syndrome, and at least in part explain selected skeletal findings in NF1, such as osteoporosis/osteopenia.

MicroRNAs regulate osteogenesis and chondrogenesis of mouse bone marrow stromal cells

MicroRNAs (miRNAs) are non-coding RNAs that bind to target mRNA leading to translational arrest or mRNA degradation. To study miRNA-mediated regulation of osteogenesis and chondrogenesis, we compared the expression of 35 miRNAs in osteoblasts and chondroblasts derived from mouse marrow stromal cells (MSCs). Differentiation of MSCs resulted in up- or downregulation of several miRNAs, with miR-199a expression being over 10-fold higher in chondroblasts than in undifferentiated MSCs. In addition, miR-124a was strongly upregulated during chondrogenesis while the expression of miR-96 was substantially suppressed. A systems biological analysis of the potential miRNA target genes and their interaction networks was combined with promoter analysis. These studies link the differentially expressed miRNAs to collagen synthesis and hypoxia, key pathways related to bone and cartilage physiology. The global regulatory networks described here suggest for the first time how miRNAs and transcription factors are capable of fine-tuning the osteogenic and chondrogenic differentiation of mouse MSCs.

Alendronate decreases orthotopic PC-3 prostate tumor growth and metastasis to prostate-draining lymph nodes in nude mice

Background

Metastatic prostate cancer is associated with a high morbidity and mortality but the spreading mechanisms are still poorly understood. The aminobisphosphonate alendronate, used to reduce bone loss, has also been shown to inhibit the invasion and migration of prostate cancer cells in vitro. We used a modified orthotopic PC-3 nude mouse tumor model of human prostate cancer to study whether alendronate affects prostate tumor growth and metastasis.

Methods

PC-3 cells (5 × 10⁵) were implanted in the prostates of nude mice and the mice were treated with alendronate (0.5 mg/kg/day in PBS, s.c.) or vehicle for 4 weeks. After sacrifice, the sizes of tumor-bearing prostates were measured and the tumors and prostate-draining regional iliac and sacral lymph nodes were excised for studies on markers of proliferation, apoptosis, angiogenesis and lymphangiogenesis, using histomorphometry and immunohistochemistry.

Results

Tumor occurrence in the prostate was 73% in the alendronate-treated group and 81% in the control group. Mean tumor size (218 mm³, range: 96–485 mm³, n = 11) in the alendronate-treated mice was 41% of that in the control mice (513 mm³, range: 209–1350 mm³, n = 13) (p < 0.05). In the iliac and sacral lymph nodes of alendronate-treated mice, the proportion of metastatic area was only about 10% of that in control mice (p < 0.001). Immunohistochemical staining of tumor sections showed that alendronate treatment caused a marked decrease in the number of CD34-positive endothelial cells in tumors (p < 0.001) and an increase in that of ISEL positive apoptotic cells in tumors as well as in lymph node metastases (p < 0.05) compared with those in the vehicle-treated mice. The density of m-LYVE-1-stained lymphatic capillaries was not changed.

Conclusion

Our results demonstrate that alendronate treatment opposes growth of orthotopic PC-3 tumors and decreases tumor metastasis to prostate-draining lymph nodes. This effect could be at least partly explained by decreased angiogenesis and increased apoptosis. The results suggest that bisphosphonates have anti-tumoral and anti-invasive effects on primary prostate cancer.

Inhibition of cyclooxygenase-2 down-regulates osteoclast and osteoblast differentiation and favours adipocyte formation in vitro

Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenases (COX) and are widely used for post-trauma musculoskeletal analgesia. In animal models, NSAIDs have been reported to delay fracture healing and cause non-union, possibly due to the drug-induced inhibition of osteoblast recruitment and differentiation. To further investigate the cellular effects of these drugs in the context of bone healing, we examined the effects of COX-1 inhibitor indomethacin and COX-2 inhibitors, parecoxib and NS398 on osteoclast and osteoblast differentiation and activity in vitro. We discovered that all tested COX-inhibitors significantly inhibited osteoclast differentiation, by 93%, 94% and 74% of control for 100 microM indomethacin, 100 microM parecoxib and 3 microM NS398, respectively. Furthermore, inhibition of COX-2 reduced also the resorption activity of mature osteoclasts. All tested COX-inhibitors also significantly inhibited osteoblast differentiation from human mesenchymal stem cells. Simultaneously, the number of adipocytes was significantly increased. The adipocyte covered areas in the cultures with 1 microM indomethacin, 1 microM parecoxib and 3 microM NS398 were 9%, 29% and 24%, respectively, as compared with 6% in the control group. This data suggests that COX-2 inhibition disturbs bone remodelling by inhibiting osteoclast differentiation and diverting stem cell differentiation towards adipocyte lineage instead of osteoblast lineage. In conclusion, our results further suggest cautious use of COX-2 inhibitors after osseous trauma.

Interaction of spin-labeled inhibitors of the vacuolar H+-ATPase with the transmembrane Vo-sector

The osteoclast variant of the vacuolar H(+)-ATPase (V-ATPase) is a potential therapeutic target for combating the excessive bone resorption that is involved in osteoporosis. The most potent in a series of synthetic inhibitors based on 5-(5,6-dichloro-2-indolyl)-2-methoxy-2,4-pentadienamide (INDOL0) has demonstrated specificity for the osteoclast enzyme, over other V-ATPases. Interaction of two nitroxide spin-labeled derivatives (INDOL6 and INDOL5) with the V-ATPase is studied here by using the transport-active 16-kDa proteolipid analog of subunit c from the hepatopancreas of Nephrops norvegicus, in conjunction with electron paramagnetic resonance (EPR) spectroscopy. Analogous experiments are also performed with vacuolar membranes from Saccharomyces cerevisiae, in which subunit c of the V-ATPase is replaced functionally by the Nephrops 16-kDa proteolipid. The INDOL5 derivative is designed to optimize detection of interaction with the V-ATPase by EPR. In membranous preparations of the Nephrops 16-kDa proteolipid, the EPR spectra of INDOL5 contain a motionally restricted component that arises from direct association of the indolyl inhibitor with the transmembrane domain of the proteolipid subunit c. A similar, but considerably smaller, motionally restricted population is detected in the EPR spectra of the INDOL6 derivative in vacuolar membranes, in addition to the larger population from INDOL6 in the fluid bilayer regions of the membrane. The potent classical V-ATPase inhibitor concanamycin A at high concentrations induces motional restriction of INDOL5, which masks the spectral effects of displacement at lower concentrations of concanamycin A. The INDOL6 derivative, which is closest to the parent INDOL0 inhibitor, displays limited subtype specificity for the osteoclast V-ATPase, with an IC(50) in the 10-nanomolar range.

Pathophysiology, risk factors and management of bisphosphonate-associated osteonecrosis of the jaw: Is there a diverse relationship of amino- and non-aminobisphosphonates?

Reports of osteonecrosis of the jaw (ONJ) in patients receiving long-term bisphosphonate therapy have appeared in the literature since 2003. This condition involves avascular necrotic bone in the area of maxilla or mandibula and there may be a secondary infection. Most cases of ONJ have been reported in cancer patients receiving the intravenous aminobisphosphonates zoledronic acid and pamidronate monthly or q 3 week; of note these are also the two most commonly used agents of this class. Risk factors for ONJ include a history of trauma, dental surgery or dental infection and intravenous bisphosphonate administration; in addition, the extent and duration of exposure to bisphosphonates also seem to correlate with the risk. Although a direct causal relationship with bisphosphonates cannot be assumed, these agents may possibly contribute to the development of ONJ by suppression of bone remodeling in the jaw which leads to increased rates of bone mineralisation and accumulation of microfractures. Clodronate, a non-aminobisphosphonate, appears to have a different mechanism of suppressing bone remodeling compared with aminobisphosphonates, and this may explain why few cases of ONJ have been reported with clodronate despite extensive use over the past 20 years; however, the potential of clodronate to reduce the risk of ONJ while providing equivalent clinical benefit to the aminobisphosphonates needs to be substantiated in controlled clinical trials. Use of bisphosphonate therapy should be carefully planned in patients with metastatic bone disease who have risk factors for ONJ, and appropriate preventive measures taken to avoid the development of this condition.

Periapical cemental dysplasia is common in women with NF1

BACKGROUND

Neurofibromatosis type 1 (NF1) is a genetic disorder with skeletal involvement. Periapical cemental dysplasia is a rare finding in the normal population.

METHOD

A total of 55 patients with NF1, 29 female and 26 male patients, were evaluated with orthopantomograms, supplemented with periapical radiographs if necessary. The vitality of the teeth was measured by two different testing methods.

RESULTS

A novel finding was the occurrence of cemental dysplasia affecting the periapical area of vital mandibular teeth in 8 adult women with NF1. Thus, cemental dysplasia was detected in 34.8% of the adult female NF1 patients, while cemental dysplasia was not present in men or children with NF1.

CONCLUSION

Periradicular cemental dysplasia is indeed a new NF1 related bone lesion type. Our finding suggests that this is the first reported sexual dimorphism in the manifestations of NF1. Cemental dysplasia of NF1 patients should not be confused with periapical findings caused by endodontic pathoses. The former do not require active therapy whereas in the latter root canal treatment is necessary.

Effects of Bioactive Peptide, Valyl-Prolyl-Proline (VPP), and Lactobacillus helveticus Fermented Milk Containing VPP on Bone Loss in Ovariectomized Rats

BACKGROUND

Valyl-prolyl-proline (VPP), a bioactive peptide formed during the fermentation with Lactobacillus helveticus LBK-16H (L. helveticus), has been shown to increase bone formation in vitro. The aim of the study was to determine whether VPP and L. helveticus fermented milk prevent bone loss in ovariectomized (OVX) rats.

METHODS

During the 12-week intervention study, the OVX rats received VPP in water or L. helveticus fermented milk, containing VPP. Sham-operated rats receiving water acted as controls. The trabecular and cortical bone mineral density were determined by peripheral quantitative computed tomography before the operation and at 4 and 12 weeks. The mechanical testing and ash weight analysis as well as the static and dynamic histomorphometrical parameters were assessed at the end of the intervention.

RESULTS

VPP given in water showed no clear effect on bone loss. L. helveticus fermented milk prevented bone loss by decreasing bone turnover and increasing the bone mineral density. Ovariectomy caused a 57% loss in the trabecular bone, which was attenuated by 16% in the L. helveticus group.

CONCLUSIONS

VPP peptide did not prevent ovariectomy-induced bone loss, which could be due to the poor bioavailability of VPP from water solution. L. helveticus fermented milk prevented bone loss, whether this is due to the VPP peptide cannot be concluded.

Lifelong risk factors for osteoporosis and fractures in elderly women with low body mass index--a population-based study

Low body weight is associated with an increased risk for osteoporosis and fractures, but the contribution of other lifestyle related factors have not been previously studied within lean elderly women. The present study evaluated the association between lifelong lifestyle factors and bone density, falls and postmenopausal fractures in elderly women with low body mass index (BMI). A population-based sample of 1,222 women aged 70 to 73 years was stratified by BMI tertiles, and all 407 women in the lowest tertile participated. Data on falls and postmenopausal fractures, physical activity, functional capacity, calcium intake, smoking, alcohol intake and medical factors at different ages were obtained by a questionnaire. Calcaneum bone mass as broadband ultrasound attenuation (BUA) was assessed with a quantitative ultrasound (QUS) device, and bone mineral density (BMD) at the distal radius was measured with a dual-energy X-ray absorptiometry (DXA). Low current physical activity was associated with lower calcaneum BUA and factors associated with higher BUA were body weight, low lifetime occupational physical activity, hormone replacement and type 2 diabetes. Weight, type 2 diabetes and thiatzide use were associated with higher radius BMD. The final multivariate model consisted of four independent factors associated with fractures: low lifetime habitual physical activity (OR 3.7, 95% CI 1.9-7.1), diabetes (OR 0.2, 95% CI 0.1-1.0), living alone (OR 1.7, 95% CI 1.0-3.0) and calcaneum BUA (1.8, 95% CI 1.3-2.4). Poor functional ability and symptoms of depression were associated with recent falling. In elderly women with low BMI, lifelong physical activity may protect from fractures, while low calcaneum bone mass and living unpartnered appear to be associated with an increased risk for fractures. Poor functional ability and presence of depression may be associated with risk of falling. Type 2 diabetes may modify the risk of low bone mass and low-trauma postmenopausal fractures. Albeit that the results of this study need to be confirmed in prospective follow-up studies, multifactorial program with the emphasis on physical and social activation in the primary care setting for preventing falls and fractures in lean elderly women is recommended.

Effect of exercise on extraskeletal risk factors for hip fractures in elderly women with low BMD: a population-based randomized controlled trial

We conducted a 30-month population-based, randomized, controlled trial in 160 elderly women at risk for fractures on the basis of a low baseline BMD. Mainly home-based weight-bearing exercise was effective in improving strength, balance, and gait.

INTRODUCTION

Evidence on the effect of exercise on extraskeletal risk factors for hip fractures comes mainly from studies in voluntary low-risk women, and no population-based, long-term interventions have been performed in elderly women with low bone mass. The aim of this study was to determine the effect of long-term weight-bearing exercise on balance, muscle strength, and gait in elderly women at risk for fractures on the basis of a low baseline BMD.

MATERIALS AND METHODS

A birth cohort of 1690 women 70-73 years of age were invited to the radius and hip BMD measurements; 96 women were excluded because of medical reasons; 160 women with radius and hip BMD values of >2 SD below the reference value were included in the trial. The participants were randomly assigned to 30 months of impact, balancing, and strengthening exercises or to no intervention. Main outcome measures were body sway length and leg strength at month 30. Secondary endpoints included gait speed, endurance, and grip strength. Outcomes were assessed at 0, 12, 24, and 30 months using blinded operators. Repeated-measures ANOVA was used to determine statistical significance. The analyses were performed on an intention-to-treat basis.

RESULTS

Body sway increased more in the control group than in the exercise group over time (time-group interaction, p < 0.001). Leg strength improved in the exercise group and decreased in the control group (interaction, p < 0.001). A significant time-group interaction (p < 0.001) in favor of the exercise group was found on the following secondary endpoints: the timed up and go test score, walking speed, and distance walked in 2 minutes.

CONCLUSIONS

Weight-bearing exercise is an effective way of modifying extraskeletal risk factors for fractures in elderly women.

Effect of impact exercise on bone mineral density in elderly women with low BMD: a population-based randomized controlled 30-month intervention

Evidence of the effect of exercise on bone loss comes mainly from studies in voluntary postmenopausal women, and no population-based, long-term interventions have been performed. The purpose of this population-based, randomized, controlled trial was to determine the effect of long-term impact exercise on bone mass at various skeletal sites in elderly women with low bone mineral density (BMD) at the radius and hip. Participants (n=160) were randomly assigned to 30 months either of supervised and home-based impact exercise training or of no intervention. The primary outcome measures were femoral neck, trochanter and total hip BMD, and the secondary outcomes were bone density measures at the radius and calcaneum. Outcomes were assessed at baseline, 12 months and 30 months using blinded operators. The analyses were performed on an intention-to-treat analysis. Mean femoral neck and trochanter BMD decreased in the control group [-1.1%, 95% confidence interval (CI) -0.1% to -2.1% and -1.6%, 95% CI -0.4% to -2.7%], while no change occurred in the exercise group. Mean trochanter BMC decreased more in the control group (-7.7%, 95% CI -9.7% to -5.6% vs. -2.9%, 95% CI -5.3 to -0.9). There were six falls that resulted in fractures in the exercise group and 16 in the control group during the 30-month intervention (P=0.019). A significant bone loss occurred in both groups at the radius and calcaneum. In multivariate analysis, weight gain was associated with increased BMD and BMC at all femur sites both in the exercise group and in the pooled groups. In conclusion, impact exercise had no effect on BMD, while there was a positive effect on BMC at the trochanter. Exercise may prevent fall-related fractures in elderly women with low bone mass.

Effects of ospemifene and raloxifene on biochemical markers of bone turnover in postmenopausal women

Ospemifene is a novel selective estrogen receptor modulator (SERM) that is initially being developed for the treatment of vaginal atrophy in postmenopausal women. However, it also shows promise in the prevention and treatment of osteoporosis. As a part of a phase II trial, we compared the effects of ospemifene and raloxifene on bone turnover in postmenopausal women. The study was conducted as a randomized, double-blind study in which 118 healthy postmenopausal women received 30 (n = 29), 60 (n = 30), or 90 mg (n = 30) ospemifene or 60 mg (n = 29) raloxifene for 3 months. Bone resorption was assessed by measuring the urinary outputs of N- and C-terminal cross-linking telopeptides of type I collagen (NTX and CTX, respectively). Bone formation was assessed by measuring bone-specific alkaline phosphatase (bone ALP), osteocalcin (OC), procollagen type I N propeptide (PINP), and procollagen type I C propeptide (PICP) in serum. All markers were studied before and at 3 months and 2-4 weeks after cessation of the medication. Urine NTX outputs decreased in all study groups, and the only statistically significant difference in NTX was observed between raloxifene and 30 mg ospemifene, which was reduced more in the raloxifene group. The output of CTX decreased most clearly in 60- and 90-mg ospemifene groups, but no significant differences between study groups emerged. A significant difference was found between the 90-mg ospemifene group and raloxifene in PINP in favor of ospemifene. No other differences in bone formation markers emerged between ospemifene and raloxifene. The study confirms the bone-restoring activity of ospemifene, which is comparable to that of raloxifene.

Decreased bone mineral density and content in neurofibromatosis type 1: lowest local values are located in the load-carrying parts of the body

Neurofibromatosis type 1 (NF1) is a dominantly inherited disease. Skeletal ailments such as short stature, kyphoscoliosis, tibial bowing and pseudarthrosis are common osseous manifestations of NF1. Previously, a correlation with scoliosis and decreased bone mineral density (BMD) of the lumbar spine has been reported in 12 NF1 patients. A total of 35 NF1 patients and 26 healthy controls were included in the present study. Of the participants over 20 years of age (26 NF1 patients and all controls) 14 were male and 12 were female, seven of whom were premenopausal. The controls were matched for age, sex and body mass index (BMI). Physical activity and medical history of NF1 patients were evaluated to screen the fractures and osseous manifestations of the disease and to rule out the factors that effect BMD. BMD and bone mineral content (BMC) were measured with DXA, using a total body program. The present study detected a lowered bone mineral density (p =0.028) and content (p <0.001) in NF1 patients of both sexes. The results of the present study also show that NF1 patients have an increased risk for osteoporosis. Among NF1 patients seven cases of osteoporosis and 13 cases of osteopenia were detected. In controls, one case of osteoporosis and 13 cases of osteopenia were detected. The location of the lowest local BMD was clustered to the load-carrying parts of the body in NF1 patients. Physical activity and the medical history of the NF1 patients did not explain the decreased BMD and BMC. The findings of the present and previous studies suggest that the pathogenesis of the osseous manifestations in NF1 may involve impaired development of the skeletal system and impaired maintenance of bone structure.

Mechanism of osteoclast mediated bone resorption--rationale for the design of new therapeutics

Bone resorption is an important cellular function in the development and physiology of the skeleton. Pathophysiology of several skeletal diseases includes either increased (for instance osteoporosis, metastatic bone disease and Paget's disease of bone) or decreased (various syndromes of osteopetrosis) bone resorption rate. Thus there is a genuine need to regulate, especially inhibit, bone resorption rate in several diseases. Bone resorption can be inhibited by several strategies. One can prevent osteoclast formation, inhibit their action or induce premature cell death. All these strategies have been used in pharmacology to inhibit bone resorption and there are also physiological regulators for each of these three different phases of in osteoclast life. Many present resorption inhibitors inhibit osteoclast formation via osteoblastic cells since they are producing a number of factors that are essential for osteoclast differentiation. Best characterized of these factors are macrophage colony stimulating factor (M-CSF) and receptor activator of NFêB ligand (RANKL). For instance sex steroids, parathyroid hormone and some interleukins are known to exert their positive or negative effects on osteoclast differentiation via the RANK/RANKL/osteoprotegrin pathway. It is not yet clear enough how specific intervention to osteoclast formation is since also other cell lineages derived from hematopoetic precursors use similar signalling pathways. An effective inhibition of bone resorption can also be achieved by inhibiting osteoclast activity to resorb bone. Examples of this category of physiological and pharmacological inhibitors are calcitonin and aminobisphosphonates, respectively. Finally one can reduce bone resorption by shortening osteoclast lifespan with substances that induce apoptosis in osteoclasts. A good example of these substances is a first generation bisphosphonate, clodronate. Several new potential molecular targets have been revealed during recent years since many individual molecules in osteoclast differentiation, function and apoptosis have been identified and their physiological functions revealed. Thus we are expecting several new bone inhibitors to be developed in following years both for experimental studies and finally also for clinical use.

α-Trinositol inhibits FGF-stimulated growth of smooth muscle and breast cancer cells

alpha-Trinositol (d-myo-inositol-1,2,6-trisphosphate), an isomer of the intracellular messenger IP(3), has been studied for its anti-inflammatory and other effects in animal experiments and in human. The mechanisms of action remain unknown. Several human pathologies are associated with uncontrolled production of fibroblast growth factors (FGFs). FGF-2 induces vascular smooth muscle cell proliferation, which contributes to restenosis after coronary balloon angioplasty. The expression of several FGFs is also increased in tumors. We studied the effects of the water- and lipid-soluble derivatives of alpha-trinositol on the FGF-2- and/or FGF-8-induced proliferation of human pulmonary artery smooth muscle cells (HPASMC) and S115 mouse breast cancer cells. alpha-Trinositol decreased the FGF-mediated proliferation of HPASMC and S115 cells. Membrane permeability did not seem obligatory since the lipid-soluble form of alpha-trinositol was less effective than the water-soluble derivative. These results suggest a new biological function for certain phosphoinositides in the modulation of FGF-regulated processes.

Effects of Lactobacillus helveticus fermented milk on bone cells in vitro

Milk fermented with Lactobacillus helveticus (L. helveticus) contains small peptides such as isoleucyl-prolyl-proline (IPP) and valyl-prolyl-proline (VPP), which inhibit the angiotensin converting enzyme (ACE). We investigated the effects of L. helveticus fermented milk whey (Lh-whey) and its components, sour milk whey, calcium and IPP and VPP peptides, on bone cells in vitro. An osteoblast assay was performed by determining the amount of deposited calcium as an index of bone formation in cultures of mouse osteoblasts formed from bone marrow-derived osteoblast precursor cells. An osteoclast assay was performed by determining the activity of tartrate-resistant acid phosphatase released into the culture medium in cultures of mouse osteoclasts formed from bone marrow-derived osteoclast precursor cells. The Lh-whey increased bone formation 1.3-1.4 times with the 1 x 10(-5), 1 x 10(-4) and 1 x 10(-3) solutions. The IPP and VPP peptides also demonstrated a significant 5-fold activation of bone formation in in vitro osteoblast cultures, whereas the sour milk whey and calcium had no effect. No significant effects were observed on osteoclasts in vitro with any of the study products. L. helveticus fermented milk whey contains bioactive components that increase osteoblastic bone formation in vitro. The effect may be due to the ACE-inhibitory IPP and VPP peptides, which showed a similar effect to that of the L. helveticus fermented milk whey.

Serum myoglobin/carbonic anhydrase III ratio as a marker of reperfusion after myocardial infarction

BACKGROUND

Coronary patency is important for short- and long-term outcome after myocardial infarction. Serum myoglobin concentration is a sensitive marker of myocardial damage and its specificity can be improved by simultaneous measurement of carbonic anhydrase III, a skeletal muscle marker. In the present study we evaluated the role of myoglobin/carbonic anhydrase III ratio as a non-invasive marker of reperfusion.

METHODS

We measured myoglobin, carbonic anhydrase III and creatine kinase MB-fraction release serially in 29 patients with acute myocardial infarction treated with thrombolysis and in 28 patients treated with primary coronary angioplasty.

RESULTS

Thrombolytic therapy was followed by a 9.1+/-2.2-fold increase in myoglobin and 10.8+/-3.3-fold increase in creatine kinase MB-fraction during the first hour of treatment, while carbonic anhydrase III remained unchanged. The peak value of myoglobin/carbonic anhydrase III ratio was found at 2 h and that of creatine kinase MB-fraction at 8 h after thrombolysis. Knowledge of the reperfusion time point during primary angioplasty and follow-up of cardiac markers revealed that cut-off points of 3 and 10 h for the peak values of myoglobin/carbonic anhydrase III ratio and creatine kinase MB-fraction can be used as indicators for reperfusion, respectively. Myoglobin/carbonic anhydrase III ratio measured before treatment and at 2 and 4 h after the onset of treatment screened 23 of those 25 patients with probable reperfusion after thrombolysis.

CONCLUSIONS

We conclude that measuring myoglobin/carbonic anhydrase III ratio during the first hours after initiation of thrombolysis may be useful in evaluating the success of reperfusion after acute myocardial infarction.

Serum myoglobin/carbonic anhydrase III ratio in the diagnosis of perioperative myocardial infarction during coronary bypass surgery

OBJECTIVE

The purpose of the present study was to evaluate the usefulness of the myoglobin/carboanhydrase III (Myo/CAIII) ratio in the diagnosis of perioperative myocardial infarction during coronary artery bypass surgery.

DESIGN

Thirty patients undergoing elective coronary artery bypass grafting (CABG) were included in the series. The patients were randomized in two groups: one received conventional normothermic retrograde blood cardioplegia, while the other was subjected to a 5-min period of ischemic preconditioning before cardioplegia. Biochemical markers for myocardial and skeletal muscle injury were measured in serial blood samples taken postoperatively from 4 h after aortic declamp.

RESULTS

Three patients were diagnosed to have suffered from perioperative myocardial infarction on the basis of significant elevations of troponin T and creatine kinase MB-isoenzyme (CK-MB) concentrations. In these particular patients the Myo/CAIII ratio increased rapidly after aortic declamping. In uncomplicated patients, the median value of the Myo/CAIII ratio remained within normal limits. There was a positive correlation between the net output of lactate during the aortic cross-clamping period and postoperative Myo/CAIII ratio. The Myo/CAIII ratio proved to be a more specific indicator for myocardial damage than myoglobin alone. The Myo/CAIII ratio was higher in the preconditioning group than in the control group.

CONCLUSION

Myo/CAIII ratio is a sensitive and specific marker for perioperative myocardial infarction increasing rapidly after aortic declamping. This ratio could also be used when assessing the extent of ischemic myocardial injury and comparing different surgical and cardioprotective techniques.

Association of low 25-hydroxyvitamin D concentrations with elevated parathyroid hormone concentrations and low cortical bone density in early pubertal and prepubertal Finnish girls

BACKGROUND

Very few studies have evaluated both parathyroid hormone (PTH) and 25-hydroxyvitamin D [25(OH)D] and their effects on bone mass in children.

OBJECTIVE

We studied the associations of serum 25(OH)D and intact PTH (iPTH) with bone mineral content (BMC) and bone mineral density (BMD) at different bone sites and the relation between serum 25(OH)D and iPTH in early pubertal and prepubertal Finnish girls.

DESIGN

The subjects were 10-12-y-old girls (n = 193) at Tanner stage 1 or 2, who reported a mean (+/- SD) dietary calcium intake of 733 +/- 288 mg/d. 25(OH)D, iPTH, tartrate-resistant acid phosphatase 5b (TRAP 5b), urinary calcium excretion, BMC, areal BMD, and volumetric BMD were assessed by using different methods.

RESULTS

Thirty-two percent of the girls were vitamin D deficient [serum 25(OH)D < or = 25 nmol/L], and 46% of the girls had an insufficient concentration (26-40 nmol/L). iPTH and TRAP 5b concentrations were significantly higher in the deficient group than in the insufficient and sufficient groups [iPTH: 43.9 +/- 15.7 compared with 38.6 +/- 11.2 pg/L (P = 0.049) and 32.7 +/- 12.1 pg/L (P < 0.001), respectively; TRAP 5b: 12.2 +/- 2.9 compared with 11.0 +/- 2.8 U/L (P = 0.009) and 10.9 +/- 1.9 U/L (P = 0.006), respectively]. The girls in the deficient group also had significantly lower cortical volumetric BMD of the distal radius (P < 0.001) and tibia shaft (P = 0.002). High iPTH concentrations were also associated with low total-body apparent mineral density and urinary calcium excretion (P < 0.007).

CONCLUSIONS

Vitamin D-deficient girls have low cortical BMD and high iPTH concentrations, which are consistent with secondary hyperparathyroidism. A low vitamin D concentration accompanied by high bone resorption (TRAP 5b) may limit the accretion of bone mass in young girls.

Long-term administration of clodronate does not prevent fracture healing in rats

Clinicians have been concerned that fractures do not heal properly in individuals exposed to bisphosphonate treatment, a treatment that strongly affects bone metabolism. The current study attempted to clarify the long-term effects of clodronate (dichloromethylene bisphosphonate) treatment on fracture healing in growing rats. Clodronate was administered subcutaneously twice a week in a dose of 2 mg/kg or 10 mg/kg. Physiologic saline served as a control. After 24 weeks of treatment, the tibiae were fractured, and the treatment was continued for another 4 weeks and 8 weeks. At both end points the cross-sectional areas of the callus, measured by peripheral quantitative computed tomography, were greater in the clodronate-treated rats than in controls, but there were no significant differences in bone mineral density. There were no significant differences between treatments in radiologic healing, histomorphometry, or in mechanical failure load of the callus with the exception of increased tensile stiffness at a dose of 2 mg/kg at 4 weeks. Clodronate treatment does not seem to prolong the fracture healing process, even when administered on a long-term basis before the fracture. Clodronate increases the size of the callus, but has only a minor effect on its biomechanical properties. The current results suggest that long-term clodronate treatment does not inhibit fracture healing.

Lifestyle factors are associated with osteoporosis in lean women but not in normal and overweight women: a population-based cohort study of 1222 women

The aim of the present population-based cohort study was to evaluate the contribution of lifelong lifestyle factors to calcaneal and distal forearm bone mass in elderly women. We studied 1222 of the 1689 eligible home-dwelling women aged 70-73 years. Lifelong occupational and leisure time physical activity, calcium intake, smoking, alcohol intake and medical history were obtained by a self-completed questionnaire. Main outcome measures were broadband ultrasound attenuation (BUA) of the calcaneus and bone mineral density (BMD) of the radius measured once in 1997-1998. The women with BMI < or = 25.1 kg m(2) had lower BUA (p < 0.0001) and radial BMD values (p < 0.0001) than women with higher BMI. Lifestyle factors associated with BUA in the leanest women were: low physical activity at work (RR 0.4; 95% confidence interval 0.2 to 0.8), low habitual exercise at the ages 30 years, 50 years and currently (RR 1.5; 1.0 to 2.4; RR 1.5; 1.1 to 2.6; RR 1.7; 1.1 to 2.7), poor mobility (RR 1.9; 1.2 to 3.0), coffee intake > or = 5 cups/day (RR 1.7; 1.1 to 2.7), type 2 diabetes (RR 0.3; 0.1 to 0.9) and hypertension (RR 0.5; 0.3 to 0.8). Type 2 diabetes protected lean women from lower distal and ultradistal radial bone density (RR 0.3; 0.1 to 0.8; RR 0.1; 0.1 to 0.5). The selected lifestyle factors were not associated with lowered calcaneal or radial bone density in the higher categories of BMI. In conclusion, risk factors for lower calcaneal and radial bone density appear to be different among lean and normal/obese women. Lifelong recreational physical activity, low physical activity at work, type 2 diabetes and hypertension seem to be associated with increased bone density, while high coffee intake may increase the risk of lower bone density in lean elderly women. These factors are potentially modifiable, and intervention studies targeted at this risk category of women are needed.

Serum osteocalcin in relation to calcaneal bone mineral density in elderly men and women: a 5-year follow-up

A 5-year follow-up study investigated serum concentrations of total (tOC) and intact (iOC) osteocalcin in relation to calcaneal bone mineral density (BMD). The study comprised two cohorts, 75- and 80-year-olds, both resident in the city of Jyväskylä, Finland. Baseline OC and BMD were obtained for 161 men and 233 women, of whom 83 men and 189 women participated in follow-up bone measurements. The mean concentration of tOC increased from 9.6 +/- 4.3 to 13.2 +/- 8.5 microg/l (P = 0.001) in men and from 11.2 +/- 4.9 to 14.0 +/- 6.1 microg/l (P < 0.001) in women, whereas mean iOC decreased from 6.4 +/- 3.0 to 5.9 +/- 3.0 microg/l (P = 0.273) and from 7.7 +/- 3.7 to 6.9 +/- 3.4 microg/l (P = 0.021) in men and women, respectively. TOC and iOC levels correlated inversely with BMD and change in BMD in both sexes (r ranged from -0.223 to -0.422 and P = 0.048 < or = 0.001). When we divided the baseline tOC and iOC values into four quartiles, the decrease in BMD was significantly greater in the third tOC quartiles in women and in the fourth tOC and iOC quartiles in men when compared with the lower quartiles. During the 5-year period, 19 men and 59 women sustained at least one fracture. These individuals with fractures had significantly higher iOC values and tended to have higher tOC values compared with the nonfracture group at baseline (P = 0.038 and 0.087, respectively). Our results indicate that baseline serum tOC and iOC were associated with bone loss and predicted fracture in the two cohorts of independently living elderly men and women.

Alendronate disturbs vesicular trafficking in osteoclasts

The nitrogen-containing bisphosphonate alendronate inhibits osteoclast-mediated bone resorption through inhibition of the mevalonate pathway. This results in impaired protein prenylation and may affect the function of small GTPases in osteoclasts. Since these proteins are important regulators of vesicle transport in cells, we investigated the possible interference of alendronate with these processes in isolated rat osteoclasts. We show here that alendronate-induced inhibition of bone resorption coincides with accumulation of tartrate-resistant acid phosphatase- and electron dense material-containing tubular vesicles in osteoclasts. Alendronate-induced changes in osteoclasts also included widening of the sealing zone areas and incomplete organization of tight attachments and ruffled borders. Osteoclasts also appeared partially detached from the bone surface, and organic matrix was typically dissolved only at the edges of the resorption pits on alendronate-coated bone slices. In contrast, resorption pits on the control and clodronate-coated bone slices were thoroughly resorbed. Inhibition of bone resorption by alendronate was not, however, related to a decrease in osteoclast number. In conclusion, our findings suggest that alendronate inactivates osteoclasts by mechanisms that impair their intracellular vesicle transport, apoptosis being only a secondary phenomenon to this.

Does combined gastrectomy and ovariectomy induce greater osteopenia in young female rats than gastrectomy alone?

Osteopenia develops in experimental animals following surgical removal of the ovaries (ovariectomy. Ovx) or the stomach (gastrectomy, Gx). Though the effect of Ovx has been ascribed to estrogen deficiency, the mechanism behind the Gx-evoked osteopenia remains unknown. In order to compare Gx- and Ovx-evoked osteopenia, young female rats were subjected to Ovx, gx, the combination of ovx and Gx, or sham operation (SHAM). Serum osteoclast-derived tartrate-resistant acid phosphatase 5b was measured as an index of bone resorption, and serum osteocalcin as an index of bone formation/turnover. Bone resorption predominated over bone formation during the first 4 days after Ovx but not later. Bone resorption predominated over bone formation throughout the first 4-week period after Gx. the changes were not additive in the ovx+Gx group. Transillumination and histomorphometry of the calvariae revealed extensive osteopenia in the Gx and the Ovx+Gx groups but not in the Ovx group. Peripheral quantitative computerized tomography of the femur metaphysis showed a decrease in the trabecular bone mineral density (BMD) in all three groups although Ovx+Gx seemed to induce greater trabecular bone loss than Gx alone. However, dual energy X-ray absorptiometry (DXA) of the intact femurs revealed reduced bone mineral content (BMC) in the Gx and Ovx+Gx groups but not in the Ovx group. Indeed, cortical bone was impaired by Gx and Ovx+Gx but not by Ovx. Hence, it seems clear that the Gx-evoked osteopenia differs from that induced by Ovx but that the osteopenia induced by Ovx+Gx is only marginally greater than that induced by Gx alone.

Bone-resorbing osteoclasts contain gap-junctional connexin-43

Intercellular gap junctions have been previously described at contact sites between surface osteoblasts, between osteoblasts and underlying osteocytes, and between osteocyte cell processes in the canaliculi. The subunits of gap junction channels are assembled from a family of proteins called connexins. In the present work, we show that rat osteoclasts cultured on bovine bone slices show connexin-43 (Cx43) staining localizing in the plasma membrane of the cells in cell-cell contacts and over the basolateral membrane of osteoclasts. The effect of heptanol, a known gap-junctional inhibitor, was studied using the well-characterized pit formation assay. Heptanol decreased the number and activity of osteoclasts. The proportion of mononuclear tartrate-resistant acid phosphatase (TRAP)-positive cells out of all TRAP-positive cells increased on heptanol treatment, suggesting a defect in the fusion of mononuclear osteoclast precursors to multinucleated mature osteoclasts. Furthermore, the total resorbed area and the number of resorption pits also decreased in the heptanol-treated cultures. These results suggest that gap-junctional Cx43 plays a functional role in osteoclasts and that the blocking of gap junctions decreases both the number and the activity of osteoclasts. This can indicate both a direct communication between multinucleated osteoclasts and mononuclear cells through gap junctions or an indirect effect through gap junctions between osteoblasts.

Determinants of bone mass and bone geometry in adolescent and young adult women

Bone mass and bone geometry are considered to have independent effects on bone strength. The purpose of this study was to obtain data on bone mass and geometry in young female populations and how they are influenced by body size and lifestyle factors. In a cross-sectional, observational study in six European countries, 1116 healthy Caucasian girls aged 11-15 and 526 women aged 20-23 participated. Their radius was scanned at the ultradistal site and at a site approximately 30% of the radius length from the distal end with dual energy X-ray absorptiometry (DXA). The following parameters were assessed from the scans: bone mineral content (BMC), bone mineral density (BMD), cortical wall thickness (CWT), middistal diameter (D), cortical index (CI = 2CWT/D), and the Breaking Bending Resistance Index (BBRI = (D4 - [D-CWT]4)/D). Calcium intake was assessed by 3-day food records and physical activity by questionnaire. Body size parameters were measured by anthropometry. All parameters showed an increasing trend with pubertal stage and age, except for physical activity and calcium intake. BMC and BMD were relatively more dependent on body weight and age at menarche, whereas variation in D and the mechanical index BBRI was better explained by differences in height and grip strength. CI and CWT were relatively independent of variation in body size, whereas BMC and BBRI especially were explained for a substantial proportion (25-33% in the young adults) by body size parameters. Dietary intake of calcium and level of physical activity seem to contribute little to variation in bone parameters.

Selective estrogenic effects of a novel triphenylethylene compound, FC1271a, on bone, cholesterol level, and reproductive tissues in intact and ovariectomized rats

FC1271a is a novel triphenylethylene compound with a tissue-selective profile of estrogen agonistic and weak antagonistic effects. It specifically binds to the estrogen receptor alpha and beta with affinity closely similar to that of toremifene and tamoxifen. To study the in vivo effects of the compound, 4-month-old rats were sham operated (sham) or ovariectomized (OVX) and treated daily for 4 weeks with various doses of FC1271a or vehicle (orally). FC1271a was able to oppose OVX-induced bone loss by maintaining the trabecular bone volume of the distal femur. Accordingly, the OVX-induced loss of bone strength was prevented at doses of 1 and 10 mg/kg. FC1271a also prevented the OVX-induced increase in serum cholesterol in a dose-dependent manner. No significant changes in uterine wet weight or morphology were observed in the OVX-rats treated with 0.1 or 1 mg/kg FC1271a, but at a dose of 10 mg/kg it had a slightly estrogenic effect. In immature rats the effect of FC1271a on uterine wet weight was less stimulatory than that of toremifene or tamoxifen, but more stimulatory than that of raloxifene or droloxifene. The appearance of the dimethylbenzanthracene (DMBA)-induced mammary tumors was inhibited by treatment of DMBA-treated rats with FC1271a in a dose-dependent manner. In human MCF-7 breast cancer cell tumors raised in nude mice in the presence of estrogen, the growth and expression of pS2 marker gene could not be maintained after estrogen withdrawal by treatment with FC1271a. No formation of DNA adducts was observed in the liver of the FC1271a-treated rats. In conclusion, the bone-sparing, antitumor, and cholesterol-lowering effects of FC1271a combined with a low uterotropic activity and lack of liver toxicity indicate that FC1271a could be an important alternative in planning antiosteoporosis therapy for estrogen deficiency.

Polarity of osteoblasts and osteoblast-like UMR-108 cells

Enveloped viruses, such as vesicular stomatitis virus (VSV) and Influenza virus, have been widely used in studying epithelial cell polarity. Viral particles of VSV-infected epithelial cells bud from the basolateral membrane, which is in contact with the internal milieu and the blood supply. Influenza-infected cells bud viral particles from the apical surface facing the external milieu. This feature can be utilized in labeling polarized membrane domains. We studied the polarity of mesenchymal osteoblasts using osteosarcoma cell line UMR-108 and endosteal osteoblasts in situ in bone tissue cultures. Immunofluorescence confocal microscopy revealed that the VSV glycoprotein (VSV G) was targeted to the culture medium-facing surface. In endosteal osteoblasts, VSV G protein was found in the surface facing bone marrow and circulation. On the contrary, Influenza virus hemagglutinin (HA) was localized to the bone substrate-facing surface of the UMR-108 cells. Electron microscopy showed that in the cases where the cells were growing as a single layer, VSV particles were budding from the culture medium-facing surface, whereas Influenza viruses budded from the bone substrate-facing surface. When the cells overlapped, this polarity was lost. Cell surface biotinylation revealed that 55% of VSV G protein was biotinylated, whereas Influenza virus HA was only 22% biotinylated. These findings suggest that osteoblasts are polarized at some point of their life cycle. The bone-attaching plasma membrane of osteoblasts is apical, and the circulation or bone marrow-facing plasma membrane is basolateral in nature.

Calcium intake is weakly but consistently negatively associated with iron status in girls and women in six European countries

Several studies indicate that intake of calcium can inhibit iron absorption especially when taken simultaneously. In the CALEUR study, a cross-sectional study among girls (mean 13.5 y) and young women (mean 22.0 y) in six European countries, the association between calcium intake and iron status was studied. In 1,080 girls and 524 women, detailed information on calcium intake was collected by means of a 3-d food record, and serum ferritin, serum iron, serum transferrin and transferrin saturation were measured as indicators of iron status. The mean levels of serum iron, ferritin and transferrin were 15.8 +/- 6.1 mmol/L, 34.5 +/- 19.1 microg/L and 3. 47 +/- 0.47 g/L, respectively, in girls and 16.9 +/- 7.5 mmol/L, 40. 2 +/- 30.5 and microg/L, 3.59 +/- 0.60 g/L, respectively, in women. A consistent inverse association between calcium intake and serum ferritin was found, after adjusting the linear regression model for iron intake, age, menarche, protein, tea and vitamin C intake and country, irrespective of whether calcium was ingested simultaneously with iron. The adjusted overall regression coefficients for girls and women were -0.57 +/- 0.20 and -1.36 +/- 0.46 per 100 mg/d increase in calcium intake, respectively. Only in girls, transferrin saturation as a measure for short-term iron status was inversely associated with calcium intake (adjusted overall coefficient -0.18 +/- 0.08). However, analysis per country separately showed no consistency. We conclude that dietary calcium intake is weakly inversely associated with blood iron status, irrespective of whether calcium was ingested simultaneously with iron.

Dietary calcium and bone density in adolescent girls and young women in Europe

The objective of this study was to investigate the association between dietary calcium intake and radial bone density among young women, over the whole range of intake and at different levels of calcium intake. The study design was a cross-sectional, observational multicenter investigation in six European countries. One thousand one hundred and sixteen healthy Caucasian girls aged 11-15 years and 526 women aged 20-23 years participated, after having been selected from larger population samples to represent a large range in calcium intake. Bone mineral density (BMD) was measured with dual-energy X-ray absorptiometry at the ultradistal and middistal radius. Calcium intake was assessed with 3-day food records. Other potential determinants of BMD were measured by anthropometry or questionnaires. Mean calcium intake among the girls varied between 609 mg/day in Italy and 1267 mg/day in Finland; intakes for women were in a similar range. After adjustment for height, weight, and age at menarche for the women, and adjustment for age, height, weight, Tanner stage, and bone area for the girls, radial BMD at both sites did not significantly vary among quartiles of calcium intakes for both age groups. In multivariate linear regression, calcium was weakly positively associated with BMD at both sites in the girls (per 100 mg of calcium: beta = 0.57 mg/cm2, p = 0.03 for middistal BMD and beta = 0.56 mg/cm2, p = 0.01 for ultradistal BMD). For middistal BMD, the association was observed predominantly in pre-menarcheal girls. The associations were no longer statistically significant after full adjustment for all determinants of BMD, except again in pre-menarcheal girls. Radial BMD in the women was not associated with calcium intake, except after full adjustment for determinants of BMD, when ultradistal BMD became inversely associated with calcium intake (per 100 mg beta = -1.02, p = 0.03); this finding was due to results in one of the countries and not found in other countries. There was no evidence for a different relation between calcium and BMD at different levels of intake; although there was a positive association at calcium intake levels < 600 mg/day, the interaction was not significant and there was no consistent trend over intake categories. These results do not support the hypothesis that dietary calcium is a determinant of peak BMD in European women, for a wide range of intake. This study does not provide evidence that Recommended Dietary Allowances for calcium should be increased.

Retrograde transport from the pre-Golgi intermediate compartment and the Golgi complex is affected by the vacuolar H+-ATPase inhibitor bafilomycin A1

The effect of the vacuolar H+-ATPase inhibitor bafilomycin A1 (Baf A1) on the localization of pre-Golgi intermediate compartment (IC) and Golgi marker proteins was used to study the role of acidification in the function of early secretory compartments. Baf A1 inhibited both brefeldin A- and nocodazole-induced retrograde transport of Golgi proteins to the endoplasmic reticulum (ER), whereas anterograde ER-to-Golgi transport remained largely unaffected. Furthermore, p58/ERGIC-53, which normally cycles between the ER, IC, and cis-Golgi, was arrested in pre-Golgi tubules and vacuoles, and the number of p58-positive approximately 80-nm Golgi (coatomer protein I) vesicles was reduced, suggesting that the drug inhibits the retrieval of the protein from post-ER compartments. In parallel, redistribution of beta-coatomer protein from the Golgi to peripheral pre-Golgi structures took place. The small GTPase rab1p was detected in short pre-Golgi tubules in control cells and was efficiently recruited to the tubules accumulating in the presence of Baf A1. In contrast, these tubules showed no enrichment of newly synthesized, anterogradely transported proteins, indicating that they participate in retrograde transport. These results suggest that the pre-Golgi structures contain an active H+-ATPase that regulates retrograde transport at the ER-Golgi boundary. Interestingly, although Baf A1 had distinct effects on peripheral pre-Golgi structures, only more central, p58-containing elements accumulated detectable amounts of 3-(2, 4-dinitroanilino)-3'-amino-N-methyldipropylamine (DAMP), a marker for acidic compartments, raising the possibility that the lumenal pH of the pre-Golgi structures gradually changes in parallel with their translocation to the Golgi region.

Differential targeting of vesicular stomatitis virus G protein and influenza virus hemagglutinin appears during myogenesis of L6 muscle cells

Exocytic organelles undergo profound reorganization during myoblast differentiation and fusion. Here, we analyzed whether glycoprotein processing and targeting changed during this process by using vesicular stomatitis virus (VSV) G protein and influenza virus hemagglutinin (HA) as models. After the induction of differentiation, the maturation and transport of the VSV G protein changed dramatically. Thus, only half of the G protein was processed and traveled through the Golgi, whereas the other half remained unprocessed. Experiments with the VSV tsO45 mutant indicated that the unprocessed form folded and trimerized normally and then exited the ER. It did not, however, travel through the Golgi since brefeldin A recalled it back to the ER. Influenza virus HA glycoprotein, on the contrary, acquired resistance to endoglycosidase H and insolubility in Triton X-100, indicating passage through the Golgi. Biochemical and morphological assays indicated that the HA appeared at the myotube surface. A major fraction of the Golgi-processed VSV G protein, however, did not appear at the myotube surface, but was found in intracellular vesicles that partially colocalized with the regulatable glucose transporter. Taken together, the results suggest that, during early myogenic differentiation, the VSV G protein was rerouted into developing, muscle-specific membrane compartments. Influenza virus HA, on the contrary, was targeted to the myotube surface.

Endoplasmic reticulum to Golgi trafficking in multinucleated skeletal muscle fibers

The organization of membrane trafficking between endoplasmic reticulum and Golgi within multinucleated muscle fibers was analyzed. We found that markers for the compartment involved in endoplasmic reticulum to Golgi trafficking exhibited perinuclear as well as interfibrillar localization. Furthermore, these markers showed prominent colocalization with microtubules. To analyze membrane trafficking, we followed the temperature-controlled transport of the G protein of the mutant vesicular stomatitis virus, tsO45, in isolated myofibers. Perinuclear and cross-striated staining were seen at 39 degrees C, while at 15 degrees C a diffuse staining component appeared along a subset of interfibrillar microtubules. At 20 degrees C, bright Golgi spots were seen to be associated with microtubules that appeared as circumnuclear rings and longitudinal bundles. Beneath the motor end plate, however, the organization of the Golgi elements and microtubules was found to be distinctive. Retrograde trafficking induced by brefeldin A resulted in the disappearance of the Golgi spots throughout the myofibers and the appearance of staining along microtubules. Thus, interfibrillar membranes seem to be active in protein export, and trafficking between endoplasmic reticulum and Golgi elements occurred throughout the myofibers. The results suggest that microtubules served as tracks for the two-way trafficking between the endoplasmic reticulum and the Golgi compartment.

Slow-release clodronate in prevention of inflammation and bone loss associated with adjuvant arthritis

The effects of slow-release calcium clodronate on rat adjuvant arthritis were investigated using two different dosing schedules. In prophylactic treatment, calcium clodronate was given on the same day as the adjuvant injection, and in therapeutic treatment, calcium clodronate administration was delayed until the animals had active disease, to day 14 postadjuvant. Calcium clodronate was given as single i.m. injections into the thigh muscles. Arthritis index, histopathology of hindpaw, quantitative histomorphometry, bone mineral density and serum osteocalcin, alkaline phosphatase and calcium were studied. Calcium clodronate given therapeutically decreased the severity of paw swelling slightly more than prophylactic treatment, a result seen as lower scores of arthritis index. Histopathological evaluation of hindpaws showed that calcium clodronate protected against inflammation-induced bone loss and reactive bone formation in the hindpaw, but not against inflammatory changes involving articular cartilage. Quantitative histomorphometric analysis of the distal femur indicated that trabecular bone area was decreased by 86% in arthritic rats compared with normal untreated controls. Both the prophylactic and the therapeutic treatment with calcium clodronate prevented this osteopenia (P < .001). Bone mineral density measured by computed tomography was also significantly reduced in distal femoral metaphysis in adjuvant arthritic rats, but restoration to virtually normal values occurred with calcium clodronate (P < .001). In both dosing schedules, we observed a suppression of arthritis, which was associated with a decrease in paw swelling and an inhibition of the severe osteopenia in the distal femoral metaphysis. The long duration of action after a single injection of calcium clodronate indicates that the insoluble salt remains at the injection site and is released slowly into the bloodstream.

Transport pathway, maturation, and targetting of the vesicular stomatitis virus glycoprotein in skeletal muscle fibers

We have infected isolated skeletal muscle fibers with the vesicular stomatitis virus or the mutant tsO45, whose glycoprotein is blocked in the endoplasmic reticulum at 39 degrees C. Immunofluorescence analysis for the viral glycoprotein indicated that the fibers were infected over their entire length at a virus dose of 10(9)/ml. When we infected the myofibers with the tsO45 mutant at 39 degrees C, the viral glycoprotein appeared to be localised to the terminal cisternae of the sarcoplasmic reticulum. Upon shifting the cultures to the permissive temperature, 32 degrees C, in the presence of dinitrophenol, which blocks vesicular transport, the viral glycoprotein proceeded to completely fill the sarcoplasmic reticulum. Thus, both the endoplasmic reticulum located at the terminal cisternae of the sarcoplasmic reticulum, and the entire endoplasmic and sarcoplasmic reticulum appeared to be continuous. Shifting the culture temperature from 39 degrees C to 20 degrees C, resulted in prominent perinuclear staining throughout the fibers, accompanied by the appearance of distinct bright dots between the nuclei. Electron microscopic immunoperoxidase labeling indicated that these bright structures represented the Golgi apparatus. When either the tsO45-infected or wild-type virus-infected fibers were incubated at 32 degrees C, the viral glycoprotein showed a staining pattern that consisted of double rows of punctate fluorescence. Immunogold labeling showed that the viral glycoprotein was present in both the transverse tubules as well as the endoplasmic/sarcoplasmic reticulum endomembranes. In addition, extensive viral budding was observed in the transverse tubules. Metabolic labeling experiments revealed that only half of the glycoprotein was processed in the Golgi, and this processed form had become incorporated into the budding viral particles. Thus, the processed viral glycoprotein was targeted to the transverse tubules. The other half of the glycoprotein remained endoglycosidase H-sensitive, suggesting its retention in the endoplasmic/sarcoplasmic reticulum endomembranes.

On the cellular localization and distribution of carbonic anhydrase II immunoreactivity in the rat brain

Evidence is provided that carbonic anhydrase-II is localized in the central nervous system to wide spread systems of oligodendrocytes and restricted astroglia populations, involving both fiber bundles and neuropil. It is suggested that CO2 formed in activated axons may, via carbonic anhydrase-II, give rise to protons controlling the excitability of surrounding neuropil. Thus, CO2 may represent an important, highly diffusible, signal in brain, involved in the tonic control of neuronal activity.

Active vacuolar H+ATPase is required for both endocytic and exocytic processes during viral infection of BHK-21 cells

Bafilomycin A1 (Baf), a specific inhibitor of the vacuolar-type proton pump, inhibited the entry of Semliki Forest virus and vesicular stomatitis virus into BHK-21 cells. The inhibition occurred at concentrations that dissipated intracellular acidic compartments. Viral infection was totally inhibited by 30 nM Baf while endocytosis of the virus or fluorescein isothiocyanate-dextran was not affected. Thus, a vacuolar-type proton pump was responsible for acidification of the endosomes needed for virus entry. When the cells were exposed to 100 nM Baf after virus entry, viral glycoprotein synthesis continued normally. The viral glycoproteins acquired resistance to endoglycosidase H, indicating arrival in the medial Golgi apparatus. However, maturation processes occurring in the trans-Golgi compartment were inhibited, and the amounts of viral glycoproteins appearing at the cell surface were reduced. Double immunofluorescence studies showed that in the presence of Baf the viral glycoproteins were found in and around mannosidase II-positive Golgi structures. To analyze whether Baf blocked transport from the trans-Golgi compartment to the cell surface, the viral glycoproteins were allowed to accumulate in the trans-Golgi network by utilizing a 20 degrees C block. Subsequent incubation at 37 degrees C in the presence of Baf did not inhibit the terminal maturation processes or transport to the cell surface, suggesting that the block was before the trans-Golgi network. These results indicate that an active vacuolar-type proton pump in the Golgi apparatus is essential for protein transport in BHK-21 cells.