bluuebunny/crossref_metadata_2025 huggingface dataset:
Perceptions of young women using SSRI antidepressants — a reclassification of stigma
Authors: Knudsen Pia , Hansen Ebba Holme , Traulsen Janine M
Published: April 2006

Objective

To contribute to an understanding of young women's perspective on using selective serotonin re-uptake inhibitors (SSRIs).

Method

Eight in-depth interviews and four re-interviews were conducted with young women (aged 21–34) using SSRIs. Informants were recruited through pharmacies in Copenhagen, Denmark. Pharmacy personnel identified potential participants based on dispensed prescriptions and gave them a contact letter with information about the study.

Key findings

When suffering from emotional problems, the women saw themselves as dysfunctional in their daily lives. They felt that they deviated from what is considered “normal” in society and thus felt stigmatised. When the women contacted their physicians they were prescribed SSRIs. After starting the medication, the women felt that they could once again function in everyday life and they felt relieved. However, the women also associated taking SSRIs with Stigmatisation due to the reputation of the medicines as “happiness pills” and the association with mental instability. The women concealed their emotional problems and medication from most people in their social networks. This was the result of the women's own anticipation of being stigmatised and their fear of negative reactions from others if they revealed the truth.

Conclusion

The young women using SSRIs felt stigmatised, initially due to their emotional problems. After the women were diagnosed, the stigma was reclassified and then became associated with taking SSRIs. The women coped primarily by trying to pass for normal. Our findings show that the SSRI users attach psychological and social meanings to their use of the drugs. Pharmacy professionals need to be aware of such meanings if they are to enhance their role in patient care.
Tau protein binds to pericentromeric DNA: a putative role for nuclear tau in nucleolar organization
Authors: Sjöberg Marcela K. , Shestakova Elena , Mansuroglu Zeyni , Maccioni Ricardo B. , Bonnefoy Eliette
Published: April 2006

The microtubule-associated tau protein participates in the organization and integrity of the neuronal cytoskeleton. A nuclear form of tau has been described in neuronal and non-neuronal cells, which displays a nucleolar localization during interphase but is associated with nucleolar-organizing regions in mitotic cells. In the present study, based on immunofluorescence, immuno-FISH and confocal microscopy, we show that nuclear tau is mainly present at the internal periphery of nucleoli, partially colocalizing with the nucleolar protein nucleolin and human AT-rich α-satellite DNA sequences organized as constitutive heterochromatin. By using gel retardation, we demonstrate that tau not only colocalizes with, but also specifically binds to, AT-rich satellite DNA sequences apparently through the recognition of AT-rich DNA stretches. Here we propose a functional role for nuclear tau in relation to the nucleolar organization and/or heterochromatinization of a portion of RNA genes. Since nuclear tau has also been found in neurons from patients with Alzheimer's disease (AD), aberrant nuclear tau could affect the nucleolar organization during the course of AD. We discuss nucleolar tau associated with AT-rich α-satellite DNA sequences as a potential molecular link between trisomy 21 and AD.
Synthesis of Medium-Sized Bicyclic Compounds by Intramolecular Cyclization of Cyclic β-Keto Radicals Generated from Cyclopropanols Using Manganese(III) Tris(2-pyridinecarboxylate)
Authors: Iwasawa Nobuharu , Funahashi Masahiro , Hayakawa Satoshi , Narasaka Koichi
Published: April 2006

Bicyclic cyclopropanols having olefinic side chain are oxidized with Mn(pic)3 to generate cyclic β-keto radicals with ring-expansion, which cyclize intramolecularly affording bicyclic radical intermediates. The cyclized radicals are trapped with various radical-trapping reagents such as electron-rich or -deficient olefins, tributyltin hydride and diphenyl diselenide to give the corresponding functionalized products.
Direct Preparation of Guanidine from Trichloroacetamide. A Potentially Important Method to (−)-Tetrodotoxin
Authors: Yamamoto Noboru , Isobe Minoru
Published: April 2006

Trichloroacetamides obtained via Overman [3,3] sigmatropic rearrangement were converted into dibenzyl guanidines. The key step was conversion of carbodiimide intermediate into guanidine by scandium or ytterbium trifluoromethane-sulfonates. This method was applied to a synthesis of guanidinium ring of (−)-tetrodotoxin.
Enzymatic Bromo-ether Cyclization of Laurediols with Bromoperoxidase
Authors: Fukuzawa Akio , Aye Mya , Takasugi Yasunori , Nakamura Masao , Tamura Mamoru , Murai Akio
Published: April 2006

Natural (3E,6R,7R)- and (3Z,6S,7S)-laurediols were subjected to enzymatic reaction with the partially purified bromoperoxidase from the red alga, Laurencia nipponica, in the presence of H2O2 and NaBr to afford laurencin and prelaureatin, respectively. The further reaction of these products with bromoperoxidase gave rise to the bicyclic bromo-ethers.
Selective Adsorption of Copper(II) over Iron(III) on Chitosan Derivative Introducing Pyridyl Group
Authors: Baba Yoshinari , Masaaki Koichi , Kawano Yoshinobu
Published: April 2006

Crosslinked N-(2-pyridylmethyl)chitosan(=PMC) with lower affinity for iron(III) was synthesized to improve the selectivity of copper(II)/iron(III). Compared with that of the crosslinked copper-complexed chitosan, the order of selectivity of copper(II)/iron(III) was reversed. Copper(II) was selectively adsorbed on PMC at a lower pH by 4 units over iron(III) from 1 mol dm−3 aqueous ammonium nitrate solution.
Quality of Medication Records and Use of Pharmacy Resources in Community Residential Care Facilities
Authors: Gray Shelly L , Odegard Peggy S , Sales Anne EB , Young Heather M , Sullivan Jean H , Hedrick Susan C
Published: April 2006

Background:

In community residential care (CRC) facilities, medication administration is often performed by unlicensed personnel with minimal knowledge in medication use. Medication management is one of the top 3 quality-of-care issues facing these facilities.

Objective:

To examine the type of medication assistance residents received, determine the proportion of facilities that used pharmacy resources, and examine the quality of facility medication records in CRC facilities (eg, adult family homes, adult residential care, assisted living facilities).

Methods:

Baseline in-person interviews were conducted with 349 residents and 299 facility providers in the Puget Sound region of Washington. Information was also obtained from facility medication records at enrollment and state databases. A pharmacist determined quality of the records using a standardized form.

Results:

The average resident was a 78-year-old white female taking 7 drugs. Medication records that were computer generated were significantly less likely to have misspelled names of drugs and errors in or absence of dose, directions for use, and route of administration. Overall, 26.3% of facilities reported that a consultant pharmacist reviewed residents' medication lists, 52.0% reported the use of preprinted lists, and 75.6% received prepackaged medications from the pharmacy. Adult family homes, the smallest facility type, were the least likely to use pharmacy-related services.

Conclusions:

The quality of handwritten medication records was a concern in CRC facilities. These facilities may benefit from services offered by pharmacies that may enhance medication management, many of which were underutilized.
Type of Preexisting Lipid Therapy Predicts LDL-C Response to Ezetimibe
Authors: Meyers Charles D , Moon Yong SK , Ghanem Hoda , Wong Nathan D
Published: April 2006

Background:

Ezetimibe as monotherapy or in combination with statins effectively lowers low-density lipoprotein cholesterol (LDL-C). However, there are few reports of ezetimibe's effect when added to ongoing non-statin lipid-lowering drugs or combination lipid-lowering therapy.

Objective:

To evaluate the impact of preexisting lipid therapy on LDL-C response to ezetimibe.

Methods:

We performed a retrospective review of all patients started on ezetimibe therapy at the Veterans Affairs Long Beach Healthcare System between March 1, 2003, and March 1, 2005. We calculated the ezetimibe-induced percent change in LDL-C in patients without concomitant changes in other lipid-lowering medications. We then stratified the population according to the type and number of preexisting lipid therapies and compared the LDL-C–lowering efficacy of ezetimibe among these groups.

Results:

Overall, ezetimibe was associated with a 23.0% reduction in LDL-C. Patients with preexisting statin monotherapy had significantly greater LDL-C reduction with ezetimibe than did those with preexisting non-statin drugs (–26.1% vs –9.3%; p = 0.0138). In patients with no preexisting lipid therapy (n = 58), monotherapy (n = 115), double therapy (n = 36), or triple therapy (n = 9), ezetimibe decreased LDL-C by 17.3%, 21.4%, 33.5%, and 38.1%, respectively. This stepwise trend in increased ezetimibe efficacy was statistically significant, even with adjustments for baseline LDL-C.

Conclusions:

Ezetimibe's LDL-C–lowering effects are most pronounced when added to preexisting combination lipid therapy. It appears to be more effective when added to statin therapy compared with other lipid-lowering therapies.
Attentional differences between groups of preschool children differentiated by teacher ratings of attention and hyperactivity
Authors: Wilding John , Burke Kate
Published: April 2006

This study aimed to extend earlier work (Wilding, Munir, & Cornish, 2001; Wilding, 2003) which showed that children (aged 6–15) who were rated by their teachers as having poor attentional ability made more errors on a visual search task than children rated as having good attentional ability. The present study used a simpler version of the search task which had previously been used to study attention in children with Fragile X syndrome (Scerif, Cornish, Wilding, Driver, & Karmiloff‐Smith, 2004) and studied performance in normal children from a younger age group. Children aged 3 and 4 were rated by teachers for attention and hyperactivity. Regression analyses, with verbal mental age (VMA), chronological age (CA), and attention rating as independent variables, found that children with higher VMA made fewer false alarms in visual searches, as did children given a better attention rating. However, none of the independent variables was related to time or distance travelled for correct responses. The relation between attention rating and error rate was non‐linear, with the error rate increasing once the attention rating fell below the mean. The results are discussed in relation to explanations of poor attention in terms of weak inhibition.
Real‐world word learning: Exploring children's developing semantic representations of a science term
Authors: Best Rachel M. , Dockrell Julie E. , Braisby Nick R.
Published: April 2006

Assessments of lexical acquisition are often limited to preschool children on forced‐choice comprehension measures. This study assessed the nature of the understandings 30 school‐age children (mean age = 6;7) acquired about the science term eclipse following a naturalistic exposure to a solar eclipse. The knowledge children acquired about eclipses and a control term comet was assessed at three points in time (baseline‐test, 2‐week post‐test and 5‐month post‐test) using a range of assessment tasks (multiple‐choice comprehension, picture‐naming, drawing and a model solar system manipulation task). Children's knowledge at the baseline‐test and 2‐week post‐test was compared with that of 15 adult controls. The analysis focused on the range of knowledge children acquired about eclipses and the relationships between aspects of knowledge they acquired. We found that children acquired extensive knowledge about eclipses, but not comets. At the 2‐week post‐test, the majority of children were able to produce the term eclipse and provided evidence of accurate comprehension and wider conceptual knowledge about solar eclipses, which was retained at the 5‐month post‐test. Further, children's ability to produce the term was related to their acquisition of ‘rich’ semantic and conceptual knowledge.
Delayed Osteotomy but Not Fracture Healing in Pediatric Osteogenesis Imperfecta Patients Receiving Pamidronate
Authors: Munns Craig FJ , Rauch Frank , Zeitlin Leonid , Fassier François , Glorieux Francis H
Published: April 2006

This study evaluated factors influencing fracture (n = 197) and osteotomy (n = 200) healing in children with moderate to severe OI. Pamidronate treatment was associated with delayed healing after osteotomy, but not after fracture. The data suggest that both pamidronate and mechanical factors influence bone healing in this cohort.

Introduction: Intravenous pamidronate is widely used to treat children with moderate to severe osteogenesis imperfecta (OI). However, the effect of this treatment on bone healing is not well characterized. We therefore retrospectively analyzed the healing of lower limb fractures and osteotomies in children with moderate to severe OI, both before and after the start of pamidronate treatment.

Materials and Methods: Bone healing was evaluated on standard radiographs after 197 lower limb fractures (132 femur and 65 tibia) in 82 patients (age at fracture, 0.0–19.9 years) and 200 intramedullary rodding procedures in 79 patients (age at surgery, 1.2–19.8 years). Delayed healing was diagnosed when a fracture or osteotomy line was at least partially visible 12 months after the event.

Results: Delayed fracture healing was observed more frequently during than before pamidronate treatment. However, the effect of pamidronate was no longer significant when age differences were taken into account (odds ratio [OR], 1.76; 95% CI, 0.61–5.10). Better mobility status was a strong independent predictor of delayed healing after fractures that occurred during pamidronate treatment. After osteotomies, delayed healing was more frequent when pamidronate had been started before surgery (OR, 7.29; 95% CI, 2.62–20.3), and this effect persisted after adjustment for multiple confounders. During pamidronate treatment, older age (OR per year of age, 1.25; 95% CI, 1.06–1.47) and osteotomy of the tibia (OR, 3.51; 95% CI, 1.57–7.82) were independent predictors of delayed healing.

Conclusions: This study suggests that pamidronate therapy is associated with delayed healing of osteotomy sites after intramedullary rodding procedures. Better mobility status, but not pamidronate treatment, seems to be predictive of delayed healing after fractures.
Common Genetic Variation of the Low-Density Lipoprotein Receptor-Related Protein 5 and 6 Genes Determines Fracture Risk in Elderly White Men
Authors: van Meurs Joyce BJ , Rivadeneira Fernando , Jhamai Mila , Hugens Wendy , Hofman Albert , van Leeuwen Johannes PTM , Pols Huibert AP , Uitterlinden André G
Published: April 2006

Both LRP5 and LRP6 genes have been implicated to play a role in bone metabolism. In a large population-based study, we related common variation in both genes to bone parameters and fractures. LRP5 variation was associated to both BMD and frame size, whereas both LRP5 and 6 variations were associated with an increased fracture risk in males.

Introduction: The low-density lipoprotein receptor-related protein 5 (LRP5) gene has a clear role in rare BMD traits and also in normal variation in peak BMD. We examined whether common variation in LRP5 and its close homolog, LRP6, plays a role in BMD in old age and fractures, the main clinical endpoint of osteoporosis.

Materials and Methods: We analyzed four variants of LRP5 and one amino acid variant of the LRP6 gene in a large prospective population-based cohort study of elderly subjects.

Results and Conclusions: In men, the LRP5 1330-valine variant was associated with decreased BMD at the lumbar spine and the femoral neck with evidence for an allele-dose effect (p = 0.001 and 0.01, respectively). The Val allele was also associated with decreased vertebral body size and femoral neck width. Haplotype analysis of studied polymorphisms did not improve the association found and suggested that the 1330 variant was driving the association. We observed a borderline significant association of the LRP6Ile1062Val polymorphism with height and vertebral body size in males. Male carriers of the LRP5 1330-valine variant had a 60% increased risk for fragility fractures, and the LRP61062-valine allele also conferred a 60% higher risk. Carriers of both the risk alleles of LRP5 and 6 had a 140% (p = 0.004) higher risk compared with noncarriers of both risk alleles and accounted for 10% of the fractures in males. The fracture risks were independent of age, height, weight, and BMD. In women, all of these associations were weaker and less consistent compared with men. The polymorphisms that were found associated were both situated in potentially important domains of the receptor and show considerable evolutionary conservation, which is evidence for functional importance of these residues.
Large-Scale Population-Based Study Shows No Evidence of Association Between Common Polymorphism of the VDR Gene and BMD in British Women
Authors: Macdonald Helen M , McGuigan Fiona E , Stewart Alison , Black Alison J , Fraser William D , Ralston Stuart , Reid David M
Published: April 2006

The VDR is a candidate gene for osteoporosis. Here we studied five common polymorphisms of VDR in relation to calcium intake and vitamin D status in a population-based cohort of 3100 British women, but found no significant association with bone mass, bone loss, or fracture.

Introduction: Population studies of vitamin D receptor (VDR) polymorphisms have produced conflicting results. We performed a comprehensive study dealing with all potential confounders in a large population to determine whether polymorphisms in the VDR gene influence bone health.

Materials and Methods: We studied 3100 women (50-63 years old) with bone markers, 25-hydroxyvitamin D, calcium, PTH, diet, and physical activity collected in 1998–2000. BMD was measured in 1990–1994 and 1998–2000. Fracture prevalence was assessed in 2002. Women were genotyped for five polymorphisms in the VDR gene: Cdx-2, Fok1, Bsm1, Apa1, and Taq1. The relationship between VDR and BMD, and interactions between VDR genotype, dietary calcium, and 25-hydroxyvitamin D, were examined using analysis of covariance.

Results: Compared with carriers of the G allele, homozygotes for the rare Cdx-2A polymorphism (n = 136) had less bone loss (−0.5 ± 1.2 versus −0.7 ± 1.0%/year {SD}; p = 0.01) and lower PTH (3.0 ± 1.6 versus 3.4 ± 2.0 pM; p = 0.03) despite similar vitamin D status. The association was not significant after correction for multiple testing or adjustment for confounders. At low calcium intakes, AA homozygotes had greater femoral neck (FN) BMD compared with carriers of the G allele, but at higher calcium intakes, the association was reversed. At low calcium intake, homozygotes for the b allele of Bsm1 had greater BMD compared with carriers of the B allele, but at higher calcium intakes, there was no difference. Similar results were seen for the Taq1 polymorphism. There was no evidence of gene-nutrient interaction when adjusted for body weight. No interactions between genotypes and vitamin D status on BMD were observed.

Conclusions: VDR does not seem to influence BMD or bone turnover in early postmenopausal white women with adequate calcium intake. Gene-nutrient interactions on BMD may be an indirect consequence of interactions between genotype and calcium intake on weight.
Low Protein Intake Is Associated With Impaired Titanium Implant Osseointegration
Authors: Dayer Romain , Rizzoli René , Kaelin André , Ammann Patrick
Published: April 2006

Low protein intake is highly prevalent among orthopaedic elderly patients. We studied the effects of an isocaloric low protein diet on the resistance to pull-out of titanium rods implanted into rats proximal tibia. Isocaloric low protein intake impairs titanium implant osseointegration, with a decreased strength needed to completely loose the implant and altered bone microarchitecture in its vicinity.

Introduction: Low protein intake is highly prevalent among elderly patients in orthopaedic wards and could retard fracture healing. It was previously shown that reduced protein intake decreases bone strength. Whether dietary protein intake could influence titanium implant osseointegration is unknown. We studied the effects of an isocaloric low protein diet on the resistance to pull-out of titanium rods implanted into rats proximal tibia.

Materials and Methods: Forty-eight 11-month-old female rats were fed isocaloric diets containing 2.5% (low protein) or 15% (normal protein) casein from 2 weeks before the implantation of a 1-mm-diameter cylindrical titanium rod in the proximal metaphysis of each tibia. Four, 6, and 8 weeks after implantation, the tibias were removed for μCT histomorphometry to quantify bone-to-implant contact and bone trabecular microarchitecture around the implant. Resistance to implant pull-out was tested by recording the maximal force necessary to completely loosen the implant.

Results: Pull-out strength was significantly lower in rats fed an isocaloric low protein diet by 6 and 8 weeks after implantation (−43%, p < 0.001 and −42%, p < 0.001, respectively) compared with rats fed a normal protein diet. Bone-to-implant contact was significantly lower in the low protein group 8 weeks after implantation (p < 0.05). Bone-to-implant contact and pull-out strength were correlated (r2 = 0.57, p < 0.0001). BV/TV around the implant was 19.9 ± 2.2% (SE) versus 31.8 ± 3.3% (p < 0.05) at 6 weeks and 20.1 ± 1.9% versus 29.8 ± 3.2% (p < 0.05) at 8 weeks after implantation in the low protein and normal protein intake groups, respectively. Trabecular thickness was 96.2 ± 3.7 versus 113.0 ± 3.6 μm (p < 0.01) at 6 weeks and 101.4 ± 2.7 versus 116.2 ± 3.3 μm (p < 0.01) at 8 weeks in the corresponding groups. In a structure model index analysis, there was a significant shift to a more rod-like pattern in the low protein diet groups. All these changes were associated with lower plasma IGF-I levels.

Conclusions: Isocaloric low protein intake impairs titanium implant osseointegration, with decreased strength needed to completely loosen the implant and altered bone microarchitecture in the vicinity of the implant.
Deletion of Aspartate 182 in OPG Causes Juvenile Paget' Disease by Impairing Both Protein Secretion and Binding to RANKL
Authors: Middleton-Hardie Catherine , Zhu Qing , Cundy Harry , Lin Jian-ming , Callon Karen , Tong Pak Cheung , Xu Jiake , Grey Andrew , Cornish Jill , Naot Dorit
Published: April 2006

Mutations in the OPG gene cause idiopathic hyperphosphatasia. We characterized the effects of one such mutation and found that the mutant OPG is poorly secreted and has reduced biological activity compared with the wildtype protein. Therefore, correct structure and cellular processing of OPG is essential for normal bone remodeling.

Introduction: Inactivating mutations in osteoprotegerin (OPG) cause juvenile Paget' disease (JPD). We recently reported a family with JPD in which affected members were homozygous for an in-frame mutation resulting in the deletion of aspartate 182 in OPG. Here we report the structural and functional characterization of the OPGΔD182 mutant protein.

Materials and Methods: Inhibition of osteoclastogenesis by the recombinant OPG proteins was studied in a murine bone marrow culture. Binding of wildtype and mutant OPG to RANKL was measured in two experimental systems: glutathione-S-transferase (GST) pull-down assay and surface plasmon resonance. Site-directed mutagenesis was used to study the glycosylation of OPGΔD182 in two potential glycosylation sites adjacent to the deleted aspartate residue at position 182. ELISA and Western blots were used to determine OPG concentrations in cell lysates and conditioned media from transiently transfected cells.

Results: OPGΔD182 inhibited the generation of osteoclasts less effectively than the wildtype protein and had a reduced ability to bind to RANKL. The apparent higher molecular weight of OPGΔD182 compared with the wildtype is a result of hyperglycosylation of asparagine residues at positions 178 and 183. Glycosylation at N183 has the potential to disrupt OPG structure by interfering with disulphide bond formation and correct protein folding. Transient transfection experiments in SaOS2 cells suggest that OPGΔD182 is retained within the cell, a typical response to unstable or incorrect protein folding.

Conclusions: Taken together, these data suggest that the deletion of aspartate 182 impairs both the secretion and activity of OPG, which in turn provides an explanation for the increased osteoclastogenesis and high bone turnover observed in JPD patients with this mutation.
Genome-Wide Scan Identified QTLs Underlying Femoral Neck Cross-Sectional Geometry That Are Novel Studied Risk Factors of Osteoporosis
Authors: Xiong Dong-Hai , Shen Hui , Xiao Peng , Guo Yan-Fang , Long Ji-Rong , Zhao Lan-Juan , Liu Yao-Zhong , Deng Hong-Yi , Li Jin-Long , Recker Robert R , Deng Hong-Wen
Published: April 2006

A genome-wide screen was conducted using a large white sample to identify QTLs for FNCS geometry. We found significant linkage of FNCS parameters to 20q12 and Xq25, plus significant epistatic interactions and sex-specific QTLs influencing FNCS geometry variation.

Introduction: Bone geometry, a highly heritable trait, is a critical component of bone strength that significantly determines osteoporotic fracture risk. Specifically, femoral neck cross-sectional (FNCS) geometry is significantly associated with hip fracture risk as well as genetic factors. However, genetic research in this respect is still in its infancy.

Materials and Methods: To identify the underlying genomic regions influencing FNCS variables, we performed a remarkably large-scale whole genome linkage scan involving 3998 individuals from 434 pedigrees for four FNCS geometry parameters, namely buckling ratio (BR), cross-sectional area (CSA), cortical thickness (CT), and section modulus (Z). The major statistical approach adopted is the variance component method implemented in SOLAR.

Results: Significant linkage evidence (threshold LOD = 3.72 after correction for tests of multiple phenotypes) was found in the regions of 20q12 and Xq25 for CT (LOD = 4.28 and 3.90, respectively). We also identified eight suggestive linkage signals (threshold LOD = 2.31 after correction for multiple tests) for the respective geometry traits. The above findings were supported by principal component linkage analysis. Of them, 20q12 was of particular interest because it was linked to multiple FNCS geometry traits and significantly interacted with five other genomic loci to influence CSA variation. The effects of 20q12 on FNCS geometry were present in both male and female subgroups. Subgroup analysis also revealed the presence of sex-specific quantitative trait loci (QTLs) for FNCS traits in the regions such as 2p14, 3q26, 7q21 and 15q21.

Conclusions: Our findings laid a foundation for further replication and fine-mapping studies as well as for positional and functional candidate gene studies, aiming at eventually finding the causal genetic variants and hidden mechanisms concerning FNCS geometry variation and the associated hip fractures.
Calcium- and Vitamin D3-Fortified Milk Reduces Bone Loss at Clinically Relevant Skeletal Sites in Older Men: A 2-Year Randomized Controlled Trial
Authors: Daly Robin M , Brown Melanie , Bass Shona , Kukuljan Sonja , Nowson Caryl
Published: April 2006

In this 2-year randomized controlled study of 167 men >50 years of age, supplementation with calcium-vitamin D3-fortified milk providing an additional 1000 mg of calcium and 800 IU of vitamin D3 per day was effective for suppressing PTH and stopping or slowing bone loss at several clinically important skeletal sites at risk for fracture.

Introduction: Low dietary calcium and inadequate vitamin D stores have long been implicated in age-related bone loss and osteoporosis. The aim of this study was to assess the effects of calcium and vitamin D3 fortified milk on BMD in community living men >50 years of age.

Materials and Methods: This was a 2-year randomized controlled study in which 167 men (mean age ± SD, 61.9 ± 7.7 years) were assigned to receive either 400 ml/day of reduced fat (∼1%) ultra-high temperature (UHT) milk containing 1000 mg of calcium plus 800 IU of vitamin D3 or to a control group receiving no additional milk. Primary endpoints were changes in BMD, serum 25(OH)D, and PTH.

Results: One hundred forty-nine men completed the study. Baseline characteristics between the groups were not different; mean dietary calcium and serum 25(OH)D levels were 941 ± 387 mg/day and 77 ± 23 nM, respectively. After 2 years, the mean percent change in BMD was 0.9-1.6% less in the milk supplementation compared with control group at the femoral neck, total hip, and ultradistal radius (range, p < 0.08 to p < 0.001 after adjusting for covariates). There was a greater increase in lumbar spine BMD in the milk supplementation group after 12 and 18 months (0.8-1.0%, p ≤ 0.05), but the between-group difference was not significant after 2 years (0.7%; 95% CI, −0.3, 1.7). Serum 25(OH)D increased and PTH decreased in the milk supplementation relative to control group after the first year (31% and −18%, respectively; both p < 0.001), and these differences remained after 2 years. Body weight remained unchanged in both groups at the completion of the study.

Conclusions: Supplementing the diet of men >50 years of age with reduced-fat calcium- and vitamin D3-enriched milk may represent a simple, nutritionally sound and cost-effective strategy to reduce age-related bone loss at several skeletal sites at risk for fracture in the elderly.
Dissimilar PTH, Gastrin, and Calcitonin Responses to Oral Calcium and Peptones in Hypocalciuric Hypercalcemia, Primary Hyperparathyroidism, and Normal Subjects: A Useful Tool for Differential Diagnosis
Authors: Bevilacqua Maurizio , Dominguez Ligia J , Righini Velella , Valdes Valeria , Vago Tarcisio , Leopaldi Ennio , Baldi Gabriella , Barrella Massimo , Barbagallo Mario
Published: April 2006

We analyzed gastrin, PTH, and calcitonin responses to oral calcium and peptones in hypocalciuric hypercalcemia, mild primary hyperparathyroidism, and normal controls. We observed diverse hormonal responses that may help in the differential diagnosis of these conditions.

Introduction: Hypocalciuric hypercalcemia (HH) is consequent to calcium-sensing receptor (CaSR) genetic mutations or anti-CaSR antibodies. CaSR is expressed in parathyroid tissue, thyroid C cells, and gastrin-secreting cells, where it has been suggested that on calcium and/or amino acid allosteric activation, promotes gastrin secretion.

Materials and Methods: We evaluated gastrin, PTH, and calcitonin responses to oral calcium (1 g) and peptones (10 g) in 10 patients with HH (mean age, 58.5 ± 10.3 years; F/M = 9/1), 15 patients with primary hyperparathyroidism (PH; mean age, 60.4 ± 8.3 years; F/M = 11/4), and 30 healthy controls (mean age, 60.3 ± 8.1 years). Statistical analyses for differences during oral loading tests were calculated with ANOVA for repeated measurements and comparisons between two groups were performed with Student's t-test.

Results: PTH response to peptones was markedly increased in patients with PH compared with flat responses in controls and HH patients (p < 0.05). Gastrin increase after oral calcium was absent in HH and PH subjects (p < 0.05 versus controls), and gastrin responses to peptones were blunted in HH and PH subjects compared with controls (p < 0.05). PTH drop and calcitonin increase after calcium load observed in controls were absent in HH and PH subjects (p < 0.05).

Conclusions: The marked difference in PTH response elicited by peptones observed in PH compared with subjects with HH may help in the differential diagnosis of these conditions without genetic studies. Peptones may stimulate CaSR-controlled hormones as an allosteric regulatory pathway. CaSR abnormalities may help to explain the different calcium- and peptones-induced hormonal responses observed in PH and HH compared with normal subjects.
Platelet-Derived Growth Factor Stimlates Sodium-Dependent Pi Transport in Osteoblastic Cells via Phospholipase Cγ and Phosphatidylinositol 3′-Kinase
Authors: Zhen Xuechu , Bonjour Jean-Philippe , Caverzasio Joseph
Published: April 2006

Inorganic phosphate (Pi) is a major regulator of cell metabolism. The Pi transport activity in the plasma membrane is a main determinant of the intracellular level of this ion. In bone-forming cells, Pi transport is important for the calcification of the bone matrix. In this study, the effect of platelet-derived growth factor (PDGF) on Pi transport activity and the signaling mechanism involved in this cellular response were analyzed. The results indicate that PDGF is a potent and selective stimulator of sodium-dependent Pi transport in the mouse calvaria-derived MC3T3-E1 osteoblast-like cells. The change in Pi transport induced by PDGF-BB was dependent on translational processes and affected the Vmax of the Pi transport system. These observations suggested that enhanced Pi transport activity in response to PDGF resulted from insertion of newly synthesized Pi transporters in the plasma membrane. The role of activation of mitogen activated protein (MAP) kinase, phospholipase C (PLC)γ or phosphatidylinositol 3-kinase (PI-3–kinase), in mediating this effect of PDGF, was investigated. A selective inhibitor of the PDGF receptor tyrosine kinase activity (CGP 53716) completely blocked PDGF-induced protein tyrosine phosphorylation of several proteins including the PDGF receptor, PLCγ, MAP kinase, and association of the p85 subunit of PI-3′-kinase. Associated with this effect, the increase in Pi transport induced by PDGF was completely blunted by 5 μM CGP 53716. Inhibition of MAP kinase activity by cAMP agonists did not influence Pi transport stimulation induced by PDGF. However, inhibitors of protein kinase C completely blocked this response. A selective inhibitor of PI-3-kinase, LY294002, also significantly reduced this effect of PDGF. In summary, these results indicate that PDGF is a potent and selective stimulator of Pi transport in osteoblastic cells. The mechanism responsible for this effect is not mediated by MAP kinase but involves tyrosine phosphorylation-dependent activation of PLCγ and PI-3-kinase.
Expression of Tenascin-C in Bones Responding to Mechanical Load
Authors: Webb Chloë M. B. , Zaman Gul , Mosley John R. , Tucker Richard P. , Lanyon Lance E. , Dr. Mackie Eleanor J.
Published: April 2006

A number of early biochemical responses of bone cells to mechanical loading have been identified, but the full sequence of events from the sensing of strain to the formation of new bone is poorly characterized. Extracellular matrix proteins can modulate cell behavior and would be ideal molecules to amplify the early response to loading. The extracellular matrix protein, tenascin-C, supports differentiation of cultured osteoblast-like cells. The current study was carried out to investigate whether expression patterns of tenascin-C in loaded bones support a role for this protein as a mediator of the osteoregulatory response to loading. Tenascin-C expression was investigated by Northern blot analysis in rat ulnae subjected to an established noninvasive loading regimen engendering physiological strain levels. RNA extracted from loaded compared with contralateral control bones 6 h after loading showed a significant increase in tenascin-C transcript expression. The presence of tenascin-C was investigated by immunohistochemistry in bones of animals killed 3, 5, or 15 days after the initiation of daily loading. In animals killed at 3 or 5 days, periosteal surfaces undergoing load-induced reversal from resorption to formation showed enhanced tenascin-C staining. In animals killed at 15 days, the bone formed in response to loading was clearly demarcated from old bone by strong tenascin-C staining of reversal lines. Within this new bone, tenascin-C staining was seen in the lacunae of older but not more recently embedded osteocytes. The results presented here indicate that tenascin-C expression by bone cells is enhanced in the early osteogenic response to loading. This may indicate that tenascin-C acts as a mediator of the mechanically adaptiveresponse.
Pooling of Clodronate Urinary Excretion Data: A New Pharmacokinetic Method to Study Drugs with Highly Variable Gastrointestinal Absorption
Authors: Castrén-Kortekangas Päivi , Löyttyniemi Eliisa , Liukko-Sipi Sirpa , Juhakoski Auni , Smal Jaana , Dr. Laitinen Kalevi
Published: April 2006

Gastrointestinal absorption of bisphosphonates is highly variable from individual to individual (between-subject variation) and from day to day (within-subject variation), a fact that creates problems both in research and in clinical use of these drugs. We conducted a randomized, two-period cross-over pharmacokinetic (phase I) study to assess the relative bioavailability of two different clodronate preparations: an 800 mg tablet and a 400 mg capsule. Urinary excretion of clodronate correlates with gastrointestinal absorption. To minimize the confounding effect of the high variability of gastrointestinal absorption, we chose as the primary parameter the cumulative amount of clodronate excreted into urine (Ae0-t) during 9 days (7 days of treatment, 2 days of follow-up). The 90% confidence interval calculated for the population medians of Ae0-t was 0.83–1.09, well within the 90% confidence interval stipulated for bioequivalence for the area under the curve values (0.80–1.25). This new procedure for pooling urinary excretion data offered a clear advantage over previous methods, and thus could presumably be used to study other drugs as well that are not metabolized and may show highly variable gastrointestinal absorption.
Is Skeletal Responsiveness to Thyroid Hormone Altered in Primary Osteoporosis or Following Estrogen Replacement Therapy?
Authors: Langdahl Bente L. , Loft Anne Gitte , Møller Niels , Weeke Jørgen , Eriksen Erik F. , Mosekilde Leif , Charles Peder
Published: April 2006

Hyperthyroidism is characterized by increased bone turnover and resorptive activity. Similar changes in remodeling are seen in osteoporosis. To study the pathogenetic role of thyroid hormone in osteoporosis, we measured concentrations of free and total thyroid hormones and investigated the sensitivity of the skeleton toward thyroid hormones in 14 osteoporotic, 16 estrogen-treated, and 15 normal postmenopausal women with comparable thyroid status. Triiodothyronine (T3, 60 μg/day for 7 days) was administered to the three groups. The skeletal response was assessed by monitoring bone alkaline phosphatase (BAP), osteocalcin (BGP), and pyridinium cross-linked telopeptide domain of type I collagen (ICTP) in serum and urinary excretion of hydroxyproline (OHP), pyridinoline (PYR), and deoxypyridinoline (DPR) at days 0, 8, 15, and 57. Women on estrogen replacement therapy exhibited lower bone turnover than the normal postmenopausal women. Markers of bone formation were reduced by 19–43% and markers of resorption by 22–48%. The osteoporotic women displayed lower bone mass at the lumbar spine and the distal forearm (p < 0.01–0.001), but the levels of biochemical markers of bone formation and resorption were comparable to values obtained in the normal postmenopausal women. T3 stimulation caused significant increases (p values ranging between 0.05–0.001) in all three groups of the resorptive markers: ICTP (47%, 47%, 45%), OHP (29%, 30%, 33%), PYR (43%, 27%, 51%), and DPR (42%, 24%, 59%). Of the formative markers, only BGP increased significantly (32%, 40%, 47%) (p < 0.001). At day 57, however, all three formative markers increased compared with day 15 (p < 0.05–0.001). No significant differences in bone markers were demonstrated between groups. In the osteoporotic group, as the only group, serum calcium increased (p < 0.05) and serum PTH fell (p < 0.05). In conclusion, osteoporosis and estrogen substitution are not characterized by altered concentrations of thyroid hormones or responsiveness to thyroid hormones at the level of individual bone cells; however, altered responses pertaining to PTH and calcium were detected.
Recombinant Transforming Growth Factor-β1 Induces Endochondral Bone in the Baboon and Synergizes with Recombinant Osteogenic Protein-1 (Bone Morphogenetic Protein-7) to Initiate Rapid Bone Formation
Authors: Ripamonti U. , Duneas N. , van Den Heever B. , Bosch C. , Crooks J.
Published: April 2006

Several members of the bone morphogenetic protein (BMP) and transforming growth factor-β (TGF-β) families are molecular regulators of cartilage and bone regeneration, although their actual roles and combined interactions in skeletal repair are poorly understood. The presence of several molecular forms suggests multiple functions in vivo as well as synergistic interactions during both embryonic bone development and regeneration of cartilage and bone in postfetal life. Here we show for the first time that recombinant human transforming growth factor-β1 (TGF-β1) induces endochondral bone formation in extraskeletal sites of adult baboons. We also show that TGF-β1 and recombinant human osteogenic protein-1 (OP-1, bone morphogenetic protein-7) synergize in inducing large ossicles in extraskeletal sites of the primate as early as 15 days after implantation. A single application of OP-1, in conjunction with an insoluble collagenous matrix as carrier (5, 25, and 125 μg/100 mg of carrier matrix) induced bone differentiation in the rectus abdominis of the baboon. This level of tissue induction was raised several-fold by the simultaneous addition of comparatively low doses of TGF-β1 (0.5, 1.5, and 5 μg), which by itself induces bone formation in the rectus abdominis at doses of 5 μg/100 mg of carrier matrix. Combinations of OP-1 and TGF-β1 yielded a 2- to 3-fold increase in cross-sectional area of the newly generated ossicles, with markedly elevated key parameters of bone formation, and corticalization of the newly formed bone by day 15, culminating in bone marrow generation by day 30. The tissue generated by the combined application of OP-1 and TGF-β1 showed distinct morphological differences when compared with OP-1–treated specimens, with large zones of endochondral development and extensive bone marrow formation. At the doses tested, synergy was optimal at a ratio of 1:20 by weight of TGF-β1 and OP-1, respectively. These results provide evidence for a novel function of TGF-β1 in the primate and the scientific basis for synergistic molecular therapeutics for the rapid regeneration of cartilage and bone.
Stimulatory Effects of Basic Fibroblast Growth Factor and Bone Morphogenetic Protein-2 on Osteogenic Differentiation of Rat Bone Marrow-Derived Mesenchymal Stem Cells
Authors: Hanada Keigo , Dennis James E. , Caplan Arnold I.
Published: April 2006

Bone marrow stroma contains multipotential mesenchymal progenitor cells which can differentiate into osteoblastic cells; we refer to these cells as mesenchymal stem cells (MSCs). Basic fibroblast growth factor (bFGF) and bone morphogenetic protein-2 (BMP-2) have been implicated in the osteogenic regulatory process by virtue of their mitogenic and differentiation activities, respectively. This study examines and compares the effects of bFGF and BMP-2 on dexamethasone (Dex)-dependent in vitro osteogenic differentiation of rat marrow–derived MSCs. A 6-day exposure to bFGF markedly stimulated cell growth and induced osteoblastic differentiation as shown by osteocalcin mRNA expression (day 14), bone nodule formation (day 18), and calcium deposition (day 18). These results indicate that bFGF enhances both mitogenic activity and osteogenic development of Dex-treated marrow MSCs. In contrast, BMP-2 did not induce osteogenesis as strongly as bFGF. Thus, exposure to BMP-2 slightly increased bone nodule number and calcium content compared with the control. Exposure of MSCs to both BMP-2 and bFGF induced expression of osteocalcin mRNA and mineralizing bone-like nodules as early as day 11 and resulted in enhancement of bone formation more markedly than either factor alone. Consistent with these results, porous calcium phosphate ceramic cubes implanted in vivo, which were loaded with MSCs pre-exposed to both bFGF and BMP-2, showed higher histologic score for bone formation than those with MSCs pre-exposed to either bFGF or BMP-2 alone. These data indicate that combined treatment with bFGF and BMP-2 synergistically enhances the osteogenic potency of bFGF in rat marrow MSC culture.
Prediction of Vertebral Strength In Vitro by Spinal Bone Densitometry and Calcaneal Ultrasound
Authors: Cheng Xiao G. , Nicholson Patrick H. F. , Boonen Steven , Lowet Geert , Brys Peter , Aerssens Jeroen , van der Perre Georges , Dequeker Jan
Published: April 2006

Spinal bone mineral density (BMD) measurements and calcaneal ultrasound were compared in terms of their ability to predict the strength of the third lumbar vertebral body using specimens from 62 adult cadavers (28 females, 34 males). BMD was measured using dual X-ray absorptiometry (DXA) in both vertebra and calcaneus. Quantitative computed tomography (QCT) was used to determine trabecular BMD, cortical BMD, cortical area, and total cross-sectional area (CSA) of the vertebral body. Bone velocity (BV) and broadband ultrasonic attenuation (BUA) were measured in the right calcaneus. Vertebral strength was determined by uniaxial compressive testing. Vertebral ultimate load was best correlated with DXA-determined vertebral BMD (r2 = 0.64). Of the QCT parameters, the best correlation with strength was obtained using the product of trabecular BMD and CSA (r2 = 0.61). For vertebral ultimate stress, however, the best correlation was observed with QCT-measured trabecular BMD (r2 = 0.51); the correlation with DXA-determined BMD was slightly poorer (r2 = 0.44). Calcaneal ultrasound correlated only weakly with both ultimate load and stress with correlation coefficients (r2) of 0.10–0.17, as did calcaneal BMD (r2 = 0.18). Both spinal DXA and spinal QCT were significantly (p < 0.001) better predictors of L3 ultimate load and stress than were either calcaneal ultrasound or calcaneal DXA. Multiple regression analysis revealed that calcaneal ultrasound did not significantly improve the predictive ability of either DXA or QCT for L3 ultimate load or stress. Calcaneal DXA BMD, bone velocity, and BUA correlated well with each other (r2 = 0.67–0.76), but were only modestly correlated with the DXA and QCT measurements of the vertebra. These data indicate that spinal DXA and spinal QCT provide comparable prediction of vertebral strength, but that a substantial proportion (typically 40%) of the variability in vertebral strength is unaccounted for by BMD measurements. Ultrasonic measurements at the calcaneus are poor predictors of vertebral strength in vitro, and ultrasound does not add predictive information independently of BMD. These findings contrast with emerging clinical data, suggesting that calcaneal ultrasound may be a valuable predictor of vertebral fracture risk in vivo. A possible explanation for this apparent discrepancy between in vivo and in vitro findings could be that current clinical ultrasound measurements at the calcaneus reflect factors that are related to fracture risk but not associated with bone fragility.