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PubMed1999

Bone metabolism and bone mineral density in childhood hypophosphatasia.

Childhood hypophosphatasia (HP) is an inborn error of bone metabolism, characterized by a reduced tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP). Bone mineral density (BMD) in childhood HP has not been reported so far. We measured BMD, in addition to markers of bone metabolism, in 6 boys with childhood HP (age 2-13 years) and in 10 parents and one sibling, each carrying the autosomal-recessive trait. BMD, measured by peripheral quantitative computed tomography (pQCT) and by dual-energy X-ray absorptiometry (DXA), was expressed as standard deviation from the normal mean (Z scores) and compared with bone mineralization by standard X-rays of the same locations. HP was confirmed by low TNSALP and its elevated substrates. In patients, BMD of the total body or spine, measured by DXA, was in the lower normal range. Total BMD of the distal metaphyses of the radius, measured by pQCT, was normal (Z score: mean +1.5). However, trabecular BMD of both radius (Z score: mean +4) and femur was grossly elevated. In parallel, X-rays showed reduced transradiancy of the radial and femoral metaphyses in all patients. In parents of patients with HP, BMD was in the lower normal range. Only one father had a decreased lumbar BMD. The discrepancy in BMD between cortical and trabecular bone of the metaphyses in patients was not present in their relatives. TNSALP levels in all first degree relatives were just below or in the lower normal range. The markers of bone turnover hydroxyproline and free deoxypyridinoline in urine were normal in patients and relatives. Hypermineralization/sclerosis of trabecular bone might serve as a compensation for a mechanically incompetent bony structure due to an impaired mineralization of cartilage caused by the genetic deficiency of alkaline phosphatase.

Absorptiometry, Photon↗
PubMed1999

Three-dimensional microstructural analysis of human trabecular bone in relation to its mechanical properties.

The purpose of this preliminary study is to explore the relationship between elastic modulus, bone mineral density (BMD), and trabecular microstructure in three dimensions. Twenty cubes of trabecular bone were processed from two lumbar vertebrae obtained from one individual. The BMD of each cube was measured by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Each cube was serially scanned by microcomputed tomography to produce three-dimensional data sets. By analyzing these data sets, three-dimensional trabecular microstructural indices of connectivity density and fractal dimension were calculated as well as histomorphometric parameters. The cubes were tested mechanically in a nondestructive manner for measurement of their elastic modulus. This preliminary study showed that: (1) bone mass index is correlated with mechanical properties, with coefficients of correlation ranging from 0.552 to 0.601; and (2) when controlling for BMD, no association could be detected between measures of structural complexity (connectivity density and fractal dimension) and elastic modulus in the craniocaudal direction of human vertebral bodies.

Biomechanical Phenomena↗
PubMed1999

Anabolic effect of aminoterminally truncated fibroblast growth factor 4 (FGF4) on bone.

Fibroblast growth factor 4 (FGF4), a member of the FGF family, plays several important roles in bone development during embryogenesis. Systemic administration of FGF4 increases bone mass in rats, which suggests the potential therapeutic usefulness of this growth factor in treatment for osteopenia and in bone regeneration. We investigated the length of FGF4 required to exert its anabolic effects, because this information may be useful in developing new molecules to mimic the effects of FGF4. Because the active site of FGF family molecules is in the carboxylterminal region, we produced aminoterminally truncated recombinant human FGF4s (rhFGF4s) of different sizes. Human FGF4 cDNA containing almost the full length of the coding region (573 bp, 191 amino acid residues) was inserted into pUC18 vector and then deleted from the 5' end using the ExoIII system. Each of the deleted FGF4 cDNAs was subcloned into a pET29(+) expression vector. Differently sized recombinant proteins were expressed in the BL21(DE3)pLysS Escherichia coli strain and then purified. The growth-stimulative effects on NIH3T3 cells of each recombinant protein were examined by means of MTT colorimetric assay. Full-length and the shortened recombinant proteins, which stimulated NIH3T3 cell growth, were then subcutaneously administered into male ddY mice (6 weeks old) every day for 2 weeks. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry (DEXA) and peripheral quantitative computed tomography (pQCT). The rhFGF4 of 134 amino acid residues, the region homologous to other members of the FGF family, exerted a growth-stimulative effect on NIH3T3 cells comparable to the full-length version of FGF4; however, the shortest version, with 111 amino acid residues, showed a limited growth-stimulative effect. Systemic administration of the rhFGF4 of 134 amino acid residues increased the bone mineral density (BMD) of femurs at a dose of 0.1 mg/kg, which was comparable to that of the full-length rhFGF4. DEXA analysis, pQCT analysis, soft X-ray photos, and contact microradiographs revealed an increase in femoral trabecular bone in FGF4-treated animals; an increase in bone formation was also evident upon histomorphometric analysis. These results indicate that the region of FGF4 that is homologous to other FGF family members provides a sufficient anabolic effect in bone and that this recombinant protein is potentially useful as a therapeutic agent in bone.

3T3 Cells↗
PubMed2002

Mobile computing in the humanitarian assistance setting: an introduction and some first steps.

We developed a Palm operating system-based handheld computer system for admin istering nutrition questionnaires and used it to gather nutritional information among the Burmese refugees in the Mae La refugee camp on the Thai-Burma border Our experience demonstrated that such technology can be easily adapted for such an austere setting and used to great advantage. Further, the technology showed tremendous potential to reduce both time required and errors commonly encountered when field staff collect information in the humanitarian setting. We also identified several areas needing further development.

Computer Peripherals↗
PubMed2004

Biological laser printing: a novel technique for creating heterogeneous 3-dimensional cell patterns.

We have developed a laser-based printing technique, called biological laser printing (BioLP). BioLP is a non-contact, orifice-free technique that rapidly deposits fL to nL scale volumes of biological material with spatial accuracy better than 5 microm. The printer's orifice-free nature allows for transfer of a wide range of biological material onto a variety of substrates. Control of transfer is performed via a computer-aided design/computer-aided manufacturing (CAD/CAM) system which allows for deposition rates up to 100 pixels of biological material per second using the current laser systems. In this article, we present a description of the apparatus, a model of the transfer process, and a comparison to other biological printing techniques. Further, examples of current system capabilities, such as adjacent deposition of multiple cell types, large-scale cell arrays, and preliminary experiments on creating multi-layer cell constructs are presented. These cell printing experiments not only demonstrate near 100% viability, they also are the first steps toward using BioLP to create heterogeneous 3-dimensional constructs for use in tissue engineering applications.

Animals↗
PubMed1999

Assessing mineral density in small trephined jawbone biopsy specimens.

This study reports the test of the hypothesis that mineral density can be precisely assessed in small trephined jawbone biopsy specimens. Mineral density was measured by dual-energy X-ray absorptiometry (DEXA) and peripheral quantitative computed tomography (pQCT). Ten fresh and ten histologically processed specimens, which were not the same, were measured. The coefficient of variations (CVs) for the alcohol stored and the histologic specimens by DEXA were respectively 1.60 and 1.71%. The CVs by pQCT for the total bone density in the alcohol stored and the histologic specimens were respectively 0.07 and 0.16%, for the trabecular bone density 0.69 and 1.04% and for the cortical bone density 0.07 and 0.12%. It was concluded that DEXA and pQCT are precise for mineral density assessment of small trephined jawbone biopsy specimens both alcohol stored and histologically processed.

Absorptiometry, Photon↗
PubMed2004

Production of complex nucleic acid libraries using highly parallel in situ oligonucleotide synthesis.

Generation of complex libraries of defined nucleic acid sequences can greatly aid the functional analysis of protein and gene function. Previously, such studies relied either on individually synthesized oligonucleotides or on cellular nucleic acids as the starting material. As each method has disadvantages, we have developed a rapid and cost-effective alternative for construction of small-fragment DNA libraries of defined sequences. This approach uses in situ microarray DNA synthesis for generation of complex oligonucleotide populations. These populations can be recovered and either used directly or immortalized by cloning. From a single microarray, a library containing thousands of unique sequences can be generated. As an example of the potential applications of this technology, we have tested the approach for the production of plasmids encoding short hairpin RNAs (shRNAs) targeting numerous human and mouse genes. We achieved high-fidelity clone retrieval with a uniform representation of intended library sequences.

Animals↗
PubMed2004

Effects of grape seed proanthocyanidins extract on mandibles in developing rats.

OBJECTIVE: Grape seed proanthocyanidins extract (GSPE), a flavonoid, has a beneficial effect on physical health, which may include the health of bone. The purpose of the present study was to investigate the effects of GSPE on mandibular bone by examining trabecular and cortical bone density, mineral content, and non-invasive bone strength in low-calcium diet rats. MATERIALS AND METHODS: Wistar male rats at 5 weeks old (n = 40) were divided into control (A), low-calcium diet (B), low-calcium diet plus standard diet (C), and low-calcium diet plus standard diet with supplementary GSPE (D) groups. Following 3 weeks of a calcium-restricted diet, group D rats were given 3 mg of GSPE as supplement in 100 g of a standard diet for the next 3 weeks. Following the 6-week experimental period, mandibular bones were examined using peripheral quantitative computed tomography (pQCT). RESULTS: There were no significant differences in body weight or trabecular bone area among the four groups. Trabecular bone density, and trabecular bone mineral content, cortical bone density, cortical bone cross-sectional area, and cortical bone mineral content were significantly higher in group D than in C. Further, Stress-strain index (SSI) values of xSSI and ySSI in group D were significantly higher than in C, although there was no significant difference in pSSI value between those two groups. CONCLUSION: Our results suggest that GSPE treatment caused an increase in both bone formation and bone strength in rat mandibles.

Animals↗
PubMed1996

Bone mass and metabolism in women aged 45-55.

OBJECTIVE: Changes in calcium homeostasis and bone mass around the climacteric are poorly understood. We examined relations between endocrine factors and indices of bone mass and metabolism in healthy women approaching the menopause. DESIGN: Cross-section study. PATIENTS: Sixty-eight spontaneously menstruating women aged 45-55. MEASUREMENTS: Bone density measured at lumbar spine (LS) and femoral neck (FN) using dual energy X-ray absorptiometry and distal non-dominant forearm using peripheral quantitative computed tomography. We recorded menstrual history, physical activity and dietary calcium, and measured serum calcium, phosphate, alkaline phosphatase, osteocalcin, vitamin D, fT3, T4, TSH, PTH, FSH and oestradiol (E2), and urinary pyridinoline (PYD) and deoxypyridinoline (DPD) excretion. RESULTS: Using serum FSH level as a marker of ovarian function, 63 subjects could be classified into one of three groups: group A (serum FSH < 10 U/l, n = 29), group B (10-35 U/l, n = 27) and group C (> 35 U/l, n = 7). Bone density fell with declining ovarian function at the LS, FN and forearm trabecular (but not cortical) sites. Serum PTH was lower in group A vs B (mean (SD) 2.68 (0.97) vs 3.52 (1.17) pmol/l, P < 0.05), but similar to group C (2.90 (1.09) pmol/l, P = NS). Serum phosphate was elevated in group C compared to groups A and B (1.17 (0.15) vs 1.04 (0.11) and 1.05 (0.13) mmol/l, P < 0.05), and urinary PYD (61.1 (8.0) vs 50.4 (11.6) and 43.9 (8.1) mumol/mol creatinine) and DPD (15.9 (3.9) vs 12.0 (3.6) and 11.4 (3.6) mumol/mol creatinine) excretion were also increased. There were no significant differences in vitamin D metabolites or osteocalcin. Multivariate analysis suggested serum osteocalcin was positively related to physical activity and serum 1,25-dihydroxycholecalciferol levels. Serum free T3 was positively correlated with urinary DPD excretion, and inversely related to serum PTH. In all subjects, serum PTH was related to body weight (r = 0.38, P = 0.002). CONCLUSIONS: Declining ovarian function before menopause is accompanied by reductions in bone mass and altered calcium metabolism. Free T3 may regulate bone resorption and indirectly modulate PTH release.

Amino Acids↗
PubMed2002

Decreased trabecular bone biomechanical competence, apparent density, IGF-II and IGFBP-5 content in acromegaly.

BACKGROUND: Earlier studies on the effect of excess growth hormone (GH) on trabecular bone have been conflicting. Since insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) in part mediate the effects of GH, the present study aimed to investigate trabecular bone composition of these growth factors in relation to biomechanical properties in acromegaly. MATERIALS AND METHODS: Trabecular bone biomechanical competence (compression test), apparent density (peripheral quantitative computed tomography, pQCT), and bone matrix contents of calcium (HCl hydrolysis) and IGFs (guanidinium-HCl extraction) were measured in iliac crest biopsies from 13 patients with active acromegaly (two women and 11 men, aged 21-61 years) and 21 age- and sex-matched controls (four women and 17 men, aged 23-64 years). RESULTS: Trabecular bone pQCT was reduced in acromegalic patients compared with controls (P = 0.005), as was biomechanical competence (P < 0.05 for all measures). These parameters were significantly positively correlated in both acromegalic patients and controls. The calcium content of trabecular bone was significantly increased in patients compared with controls. No significant differences were found in trabecular bone content of IGF-I, IGFBP-3, or osteocalcin. However, IGF-II and IGFBP-5 content was decreased (P < 0.001 and P < 0.05, respectively). CONCLUSIONS: The present study demonstrates reduced trabecular biomechanical competence and apparent density in acromegaly, supporting previous observations of an unfavourable effect of chronic excess GH on the axial skeleton. Furthermore, we demonstrate decreased trabecular bone content of IGF-II and IGFBP-5 in these patients. However, we found no direct causal relationship between trabecular bone density and bone content of IGF-system components.

Acromegaly↗
PubMed2001

Effects of long-term testosterone substitutive therapy on bone mineral content in men with hypergonadotrophic hypogonadism.

Hypogonadism is one of the crucial risk factors for male osteopenia and osteoporosis. There are few studies on the effects of long-term and consistently administered testosterone substitutive therapy on bone mineral density in men with gonadal androgen deficiency, and their results have been susceptible to various interpretations. The aim of our study was an evaluation of bone mineral content in 26 men, aged 18-57 years, with hypergonadotrophic hypogonadism who underwent long-lasting androgen re-placement therapy with testosterone esters (Omnadren 250), which conditioned proper psychosomatic androgenization. The control group comprised 405 healthy men, aged 20-60 years, a representative sample of the local male population. Among all examined men and in the control group, trabecular, cortical and total bone mineral content at the distal radius of the nondominant hand were assessed by peripheral quantitative computed tomography using the Stratec 960 apparatus. In 11 hypogonadal men (42.3%), the trabecular bone mineral content was found to be within normal ranges; in 15 patients (57.7%) its values were below -1 standard deviation (SD) (osteopenia). In six patients (23.1%), the cortical bone mineral content was between +1 SD and the arithmetic mean, X; in 13 examined men (50%), the cortical bone mineral content was below X and above -1 SD. Osteopenia was diagnosed in six hypogonadal males, whereas osteoporosis was found in one man (cortical bone mineral content below -2.5 SD). Only in seven of the examined men (26.9%) was the total bone mineral content found within normal ranges, whereas in 19 men (73.1%) the total bone mineral content was below -1 SD (osteopenia). Despite the testosterone replacement in hypogonadal men, the greatest reduction of bone mineral content was found in its trabecular and total values. Among all the men examined, the trabecular and total bone mineral contents were below the mean of our own reference values. The results show that long-term and consecutively administered testosterone replacement in conventional doses, despite the normalization of serum androgen levels and the promotion of proper somatic development, does not simultaneously eliminate hypogonadal osteopenia in every case. The individually differentiated response to exogenous androgens is a characteristic feature of male hypogonadism. This study emphasizes the necessity of regular measurements of bone mineral density in hypogonadal men, as the densitometric parameters should be accepted as an osteologic (and very important) marker of androgenization of the male organism.

Adolescent↗
PubMed2002

Influence of dietary phosphorus deficiency with or without addition of fumaric acid to a diet in pigs on bone parameters.

The purpose of this study was to examine if substantial bone loss occurs in weaned pigs by feeding a phosphorus-deficient diet with or without fumaric acid. Eighteen weaned pigs were used. The animals were assigned to three groups: group C (control; 0.65% P on DM basis), group LP (low phosphorus; 0.37% P on DM basis) and group LPF (low phosphorus plus fumaric acid; 0.35% P on DM basis plus 2% fumaric acid). These three diets were fed to the groups for a period of four weeks after a two-week adaptation period. Blood samples were collected once a week. Carboxyterminal telopeptide of type I collagen (ICTP) in serum was used as a bone resorption marker. Osteocalcin (OC) and bone-specific alkaline phosphatase (bAP) were used as bone formation markers. Bone mineral density (BMD) and content (BMC) were determined by peripheral quantitative computer tomography. BAP activities significantly increased (24%) in group LPF, and at the last sampling day group LPF had significantly increased activities in comparison to group C. In contrast, ICTP concentrations significantly increased with time in group LP and LPF, and at the last sampling day group LPF had significantly increased activities in comparison to group C. BMD and BMC in femur and tibia significantly decreased in group LP and LPF. The results show that P-deficient diets induce a bone loss. Fumaric acid did not influence the degree of bone loss. With a better understanding of its effect on bone, dietary phosphorus requirements in pigs could be more precisely defined.

Adaptation, Physiological↗
PubMed2002

Influence of a vegetarian diet versus a diet with fishmeal on bone in growing pigs.

This study was conducted to examine if substantial bone loss occurs in growing pigs fed a vegetarian diet in comparison with a diet containing fishmeal. Twelve 6-week-old weaned pigs were assigned to two groups: group V [vegetarian diet; 0.61% phosphorus (P) in dry matter until 25 kg and 0.46% P until the end of the experiment] and group F (fishmeal diet; 0.61% P in dry matter until 25 kg and 0.46% P until the end of the experiment). Phytase was added to both diets. These two diets were fed to the two groups for a period of 6 weeks. Blood samples were collected weekly, faeces were collected three times a week. Concentrations of osteocalcin (OC) and carboxyterminal telopeptide of type I collagen (ICTP) were measured in serum, using a radioimmunoassay, and bone-specific alkaline phosphatase (bAP) was measured using an enzyme immunoassay. Bone mineral density (BMD) and content (BMC) were determined by peripheral quantitative computer tomography (pQCT) in the tibia and phalanx. In addition, 1,25-dihydroxyvitamin D (VitD) and parathyroid hormone (PTH) were measured in serum. The digestibility of P was significantly decreased in group V. Significant changes in bAP activities and OC concentrations occurred with time during the 6 weeks. ICTP concentrations were significantly higher in group V. Total BMC and BMD in the tibia and BMD in the phalanx significantly decreased in group V. The results show that a vegetarian diet induces a significant loss of bone and a higher bone formation in group V compared with group F, although phytase was added to both diets. The dietary requirements for P in pigs, especially in the context of feeding vegetarian diets and adding an appropriate amount of phytase, should be investigated further.

6-Phytase↗
PubMed2003

Skeletal growth and long-term bone turnover after enterocystoplasty in a chronic rat model.

OBJECTIVE: To investigate skeletal growth and bone metabolism in a chronic animal model of urinary diversion. MATERIALS AND METHODS: Young male Wistar rats (120) were allocated randomly to four groups undergoing: ileocystoplasty, ileocystoplasty and resection of the ileocaecal segment, colocystoplasty, and controls. All animals received antibiotics for 1 week after surgery; half of each group remained on oral antibiotics. Bone-related biochemistry was measured in serum and urine. Dual-energy X-ray absorptiometry and peripheral quantitative computed tomography (pQCT) were used to determine bone mass ex vivo. RESULTS: Most (90%) of the rats survived the study period (8 months); six rats died from bowel obstruction at the level of the entero-anastomosis and four had to be killed because of persistent severe diarrhoea. Vital intestinal mucosa was found in all augmented bladders. There were no differences in bone length and volume. Loss of bone mass was almost exclusively in rats with ileocystoplasty and resection of the ileocaecal segment (-37.5%, pQCT, P < 0.01). There was no hyperchloraemic metabolic acidosis or gross impairment of renal function. Hypomagnesaemia, hypocalcaemia and decreased insulin-like growth factor-binding protein 3 were the only significant findings on blood analysis. Deoxypyridinoline crosslinks in urine were higher in rats with an enterocystoplasty than in controls. CONCLUSIONS: Enterocystoplasty in rats neither impairs skeletal growth nor bone quantity, but leads to significant loss of bone mass when combined with resection of the ileocaecal segment. Rarefaction of the trabecular network is confined to the metabolically highly active cancellous compartment, most likely as a consequence of intestinal malabsorption.

Absorptiometry, Photon↗
PubMed2000

Intermittent administration of parathyroid hormone (1-37) improves growth and bone mineral density in uremic rats.

BACKGROUND: Parathyroid hormone (PTH) is secreted in a pulsatile fashion. Continuous infusion of PTH(1-84) resulted in a net decrease in trabecular bone volume. Differential effects have been reported following an intermittent application of PTH. We investigated the effects of a continuous infusion and of an intermittent (2 times daily subcutaneously) administration of PTH(1-37) on growth and bone mineral density (BMD) in healthy and uremic rats. METHODS: Two-stage subtotal nephrectomy was performed on 130 g female Sprague-Dawley rats. PTH(1-37) or solvent was administered through minipumps in sham-operated and uremic rats (60 microg/kg x day for 2 weeks). The effect of intermittent administration was tested with a subcutaneous injection of solvent: 30 microg/kg PTH(1-37) two times per day, 100 pmol calcitriol (C)/kg two times per day, or both. The length (snout-tailtip) and BMD were measured at the start of uremia and at sacrifice. BMD was measured by peripheral quantitative computer tomography at the proximal tibia, 6 and 12 mm distal of the kneejoint space. Femur bone morphology was assessed by x-rays, and calcium content was measured by atomic absorption spectrophotometry. RESULTS: Length gain was not altered by the continuous infusion of PTH. In contrast, it was significantly increased by intermittent PTH (control solvent 5.35 +/- 0.37 cm vs. control PTH 6.19 +/- 0.47 cm; uremia solvent 4.78 +/- 0.20 cm vs. uremia PTH 6.17 +/- 0.36 cm; P < 0.05). Intermittent PTH but not C increased BMD in uremic rats (Delta total BMD 134 + 13.3 vs. 76.3 +/- 11.5 mg/mL; P < 0.05). X-rays revealed increased bone mass following treatment with PTH but not with C. Uremia decreased bone calcium content (64 +/- 0.3 vs. 73. 3 +/- 2.5 mg/mL), which was normalized by PTH (80 +/- 3.6 mg/mL, P < 0.05) but not by C (69 +/- 1.9 mg/mL). CONCLUSION: Pulsatile administration of PTH does not adversely affect, but improves longitudinal growth independent of concomitant treatment with C. At the same time PTH increases BMD and the calcium content of bone.

Animals↗
PubMed2002

Regular Tai Chi Chuan exercise may retard bone loss in postmenopausal women: A case-control study.

OBJECTIVE: To evaluate the potential benefits of regular Tai Chi Chuan exercise on the weight-bearing bones of postmenopausal women. DESIGN: Case-control study. SETTING: University medical school in Hong Kong. PARTICIPANTS: Postmenopausal women (age range, 50-59y), including 17 self-selected regular Tai Chi Chuan exercisers (TCE) with over 4 years of regular exercise, and 17 age- and gender-matched nonexercising controls (CON). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Bone mineral density (BMD) in the lumbar spine and proximal femur was measured at baseline and at follow-up 12 months later by using dual-energy x-ray absorptiometry (DXA) and in the distal tibia using multislice peripheral quantitative computed tomography (pQCT). RESULTS: Baseline results showed that the TCE group had significantly higher BMD (10.1%-14.8%, all P<.05) than the CON group in the lumbar spine, proximal femur, and the ultradistal tibia. The follow-up measurements showed generalized bone loss in both groups. Although both DXA and pQCT measurements revealed decelerated rates of bone loss in the TCE group, only the more sensitive pQCT showed significantly reduced rate of bone loss in trabecular BMD of the ultradistal tibia (TCE vs CON: -1.10%+/-1.26% vs -2.18%+/-1.60%, P<.05) and of cortical BMD of the distal tibial diaphysis (TCE vs CON: -0.90%+/-1.36% vs -1.86%+/-0.93%, P<.05). CONCLUSION: This is the first case-control study to show that regular Tai Chi Chuan exercise may help retard bone loss in the weight-bearing bones of postmenopausal women.

Bone Density↗
PubMed2002

Improved bone biomechanical properties in xylitol-fed aged rats.

Our previous studies have shown that dietary xylitol protects against weakening of bone biomechanical properties in experimental postmenopausal osteoporosis. To study whether xylitol preserves bone biomechanics also during aging, a long-term experimental study was performed with rats. Twenty-four male Sprague-Dawley rats were divided into 2 groups. The rats in the control group (NON-XYL group) were fed a basal rat and mouse no. 1 maintenance (RM1) diet, while the rats in the experimental group (XYL group) were continuously fed the same diet supplemented with 10% xylitol (wt/wt). The rats were killed after 20 months. Their femurs were prepared for biomechanical analyses and scanning analyses with peripheral quantitative computed tomography (pQCT). In 3-point bending of the femoral diaphysis, maximum load, maximum elastic load, stiffness, energy absorption, elastic energy absorption, ultimate stress, and yield stress were significantly greater in the XYL group than in the NON-XYL group. This indicates a xylitol-induced improvement of both structural and material strength properties of cortical bone. Accordingly, the maximum load of femoral neck was significantly greater in the XYL group. In the pQCT analysis of femoral diaphysis, cortical bone area, cortical thickness (CtTh) periosteal circumference, and cross-sectional moment of inertia were greater in the XYL group. The endosteal circumference was smaller in the XYL group. In the pQCT analysis of the femoral neck cortical area of the midneck was significantly greater in the XYL group. This data indicates that xylitol exerted beneficial effects on the cross-sectional architecture of the bones. In conclusion, continuous moderate dietary xylitol supplementation leads to improved bone biomechanical properties in aged rats concerning both bone structural and material strength properties.

Aging↗