Cortical and trabecular bone microarchitecture and turnover in alcohol-induced chronic pancreatitis: a histomorphometric study

Alcohol-induced chronic pancreatitis is associated with bone loss, but bone histomorphometric data describing the mechanism of cortical (Ct) and trabecular (Tb) bone loss are scarce. In this case-control study, we investigated 13 black male patients aged 41.2 ± 8.9 years with alcohol-induced chronic pancreatitis by routine iliac crest cortical and trabecular histomorphometry and by biochemistry relevant to bone, liver function, and iron overload. Patients showed lower values for Ct thickness (P = 0.018), endocortical (Ec) wall thickness (P = 0.0002), Tb bone volume (0.019), Tb thickness (0.001), Tb wall thickness (P < 0.0001), Ec osteoid thickness (P = 0.001), Ec mineral apposition rate (P = 0.011), and Ec bone formation rate (P = 0.035). Ec eroded surface (P = 0.004) was elevated compared to controls. Tb osteoid thickness (P = 0.14) and Tb mineral apposition rate (P = 0.195) tended to be lower than in controls. Levels of 25-hydroxyvitamin D (P < 0.005), serum magnesium (P = 0.02), and ascorbic acid (P = 0.049) were lower and urine calcium/creatinine ratios higher than in controls. Alkaline phosphatase and gamma-glutamyl transpeptidase (GGT) were negatively correlated but iron markers were positively correlated with bone structural and formation variables. The histomorphometric data were found to be consistent with alcohol bone disease. Osteomalacia was not a feature. Secondary pathogenetic factors were liver disease, hypovitaminosis D and C, diabetes mellitus, and possibly chronic pancreatitis.     

Age-related changes in cortical bone in men: metacarpal bone mass measurement study

Metacarpal cortical bone mass was measured in 507 healthy Japanese men aged 40–95 years, using a microdensitometer to determine age-related changes in cortical bone in these middle-aged and elderly men. Total bone mass showed a significant negative correlation with age (r = −0.281; P < 0.0001). While bone width showed no significant correlation with age, bone marrow width showed a significant positive correlation (r = 0.210; P < 0.0001), and cortical bone width and cortical bone density showed a significant negative correlation with age (r = −0.265; P < 0.0001; r = −0.268; P < 0.0001, respectively). On the other hand, cortical bone width and cortical bone density showed a significant positive correlation with total bone mass (r = 0.814; P < 0.0001; r = 0.474, P < 0.0001, respectively). These findings suggest that cortical bone mass decreases significantly with aging in middle-aged and elderly men, perhaps as a result of two factors — decreased cortical bone width, ie, cortical bone thinning due to bone loss at the endosteal side of the cortex, and decreased cortical bone density due to progression of intracortical porosity. Cortical bone thinning may influence age-related cortical bone loss more than decreasing cortical bone density. Received for publication on Feb. 25, 1999; accepted on July 18, 1999     

Age-related changes in cortical bone in women: Metacarpal bone mass measurement study

The mechanism of age-related cortical bone loss was investigated in 229 Japanese women, 41–94 years of age, by metacarpal bone mass measurement. While no significant correlation was found between bone width and age, a significant increase in bone marrow width, and significant decreases in cortical bone density and total bone mass were observed in association with aging (P < 0.0001). There was a significant negative correlation between total bone mass and bone marrow width (r=−0.239; P < 0.0005), and significant positive correlations between both total bone mass and cortical bone density (r= 0.539; P < 0.0001) and cortical bone width (r= 0.839; P < 0.0001). The findings suggested that age-related cortical bone loss in middle-aged and elderly women resulted from two different factors; a decrease in cortical bone density caused by progression of intracortical porosity, and a decrease in cortical bone width as a result of bone loss on the endosteal surface. The latter had a greater influence on an age-related cortical bone loss than the former. Received for publication on May 19, 1997; accepted on Oct. 15, 1997     

Osteocalcin and bone morphometric parameters in adults without bone disease

Summary Serum bone Gla-protein (s-BGP or osteocalcin) and other serum biochemical parameters were measured in 19 subjects (8 women and 11 men, aged 20–82 years) without any bone disease. Each subject simultaneously underwent an iliac crest biopsy; tetracycline double-labeling was performed in 11 subjects, allowing correlations between s-BGP and bone histomorphometric parameters. s-BGP was significantly correlated with static bone parameters: trabecular bone volume (r=0.74;P<0.001), osteoid surfaces (r=0.69;P<0.001), osteoblastic surfaces (r=0.68;P<0.002); dynamic bone formation parameters: total labeled surfaces (r=0.72;P<0.01); and the bone formation rate (r=0.69;P<0.01). We conclude that s-BGP is a valuable marker for evaluating bone formation in healthy adult subjects.     

High-power diode laser at 980 nm for the treatment of benign prostatic hyperplasia: ex vivo investigations on porcine kidneys and human cadaver prostates

Diode laser systems at 980 nm have been introduced for the treatment of lower-urinary-tract-symptoms (LUTS) suggestive of benign prostatic enlargement (BPE). However, the coagulation and vaporization properties are unknown. We therefore aimed to evaluate these properties in ex vivo models in comparison with the kalium-titanyl-phosphate-(KTP) laser. The diode laser treatment was applied to isolated, blood-perfused porcine kidneys and fresh human cadaver prostates (HCPs) at different generator settings. We performed histological examination to compare the depth of coagulation and vaporization. The diode laser showed larger ablation and coagulation characteristics than the KTP laser did. Ablation of the diode laser was found to be 1.79-times (120 W in porcine kidney, P < 0.0001) and 3.0–5 times (200 W in HCP, P < 0.0005) larger. The diode laser created a nine-times (120 W in porcine kidney, P < 0.0001) and seven-times (200 W in HCP, P < 0.0001) deeper necrosis zone. The diode laser vaporization was highly effective ex vivo. Owing to the laser’s deep coagulation zones, in vivo animal experiments are mandatory before the diode laser (980 nm) is applied in a clinical setting, so that damage to underlying structures is prevented.     

Bone Histomorphometry in Male Idiopathic Osteoporosis

The pathogenesis of male osteoporosis at the cellular level is still elusive. We performed histomorphometric analysis of bone biopsy samples from 51 eugonadal men with idiopathic osteoporosis. Their median age was 54 (range 29–73) years. Eighty-two percent of the patients had a fracture history, and 57% had vertebral fractures. Bone volume, trabecular thickness, wall thickness, and osteoid thickness were significantly reduced in osteoporotic men compared with healthy men. Erosion depth was similar, as were the bone remodeling parameters such as bone formation rate, mineral apposition rate, and activation frequency. In the osteoporotic men, osteoid thickness was correlated to bone mineral density at the lumbar spine (R ² = 0.19, P < 0.01); together with wall thickness, the two parameters could explain 27% of the variation in lumbar spine bone mineral density. The osteoid thickness was correlated to anthropometric variables such as body weight (R ² = 0.24, P < 0.001) and body mass index (R ² = 0.14, P < 0.01), as well as to serum estradiol levels (R ² = 0.14, P < 0.01) and to the ratio insulin-like growth factor-1 (IGF-1) to IGF-binding protein-1 (IGFBP-1) (R ² = 0.12, P < 0.01). Regression analysis showed that 36% of the variation in osteoid thickness could be predicted by body weight and estradiol levels. In conclusion, bone histomorphometry in male idiopathic osteoporosis was characterized by thin bone structural units, which might suggest osteoblast dysfunction. Bone histomorphometry parameters were associated with low body weight, low estradiol levels, and increased levels of IGFBP-1, supporting the notion that estrogens and IGFs play regulatory roles in male bone turnover.     

Bone Quality and Bone Strength in BXH Recombinant Inbred Mice

The relationship between bone quality and strength was studied in 11 BXH recombinant inbred (RI) strains of mice. The bone quality parameters studied were bone mineralization, microhardness, architecture, and connectivity. Previous studies have demonstrated considerable variability in bone density, biomechanical properties, and microstructure among inbred strains of mice. In particular, C3H/HeJ (C3H) mice exhibit thicker femoral and vertebral cortices and fewer trabeculae in the vertebral body compared with C57BL/6J (B6) mice, despite having similar vertebral bone strength. A set of RI mouse strains has been generated from B6 and C3H (denoted BXH) in an attempt to isolate genetic regulation of numerous traits, including bone. The objective of this study was to investigate relationships among bone quality and bone strength in femurs and vertebrae among BXH RI mice. The study involved 11 BXH RI strains of female mice (n = 5−7) as well as the B6 and C3H progenitor strains. Parameters contributing to bone quality were evaluated, including BMD, bone mineralization, microhardness, architecture, and connectivity. There was a strong correlation between femoral and vertebral BMD in all strains (P < 0.001) except in BXH-9 and -10 (P < 0.001). Within the vertebrae, cortical bone was more mineralized than trabecular bone, and a strong correlation existed between the two (P < 0.001). However, cortical microhardness did not differ from trabecular microhardness. Cortical bone was more mineralized in the femur than in the vertebrae and significantly harder, by 30%. There was a wide range in trabecular connectivity, architecture, and femur geometry among BXH RI strains. BMD explained 43% of vertebral bone strength but only 11% of femoral bone strength. Trabecular connectivity explained an additional 8% of vertebral strength, while mineralization and femur geometry explained 7% and 50% of femoral strength, respectively. Different bone quality parameters had varying influences on bone mechanical properties, depending on bone site. BMD may play a larger role in explaining bone strength in the vertebrae than in the femur. Moreover, cortical bone in the femur is harder than in vertebrae. The control of cortical bone material properties may be site-dependent.     

Specific Changes of Urinary Excretion of Cross-Linked N-Telopeptides of Type I Collagen in Pre- and Postmenopausal Women: Correlation with Other Markers of Bone Turnover

Urinary excretion of cross-linked N-telopeptide of type I collagen (NTx) has been reported to be a specific marker of bone resorption [18]. We assessed a new immunoassay for NTx as an indicator of changes in bone resorption caused by spontaneous menopause and compared cross-sectionally the levels of urinary NTx, hydroxylysylpyridinoline (HP), lysylpyridinoline (LP), hydroxyproline (OH-Pr), other serum biochemical indices, and lumbar spine and proximal femur bone mineral density (BMD). Eighty-one Japanese women aged 22–77 participated in this study; 36 were premenopausal and 45 were postmenopausal. Urinary HP, LP, and NTx stayed at low levels in the premenopausal period and rose 21%, 30%, and 67% in the postmenopausal period, respectively. The rise in LP and NTx was statistically significant (P < 0.01), suggesting that NTx is mostly released from bone matrix when bone resorption is accelerated. When premenopausal women were divided into two age groups and postmenopausal women were divided into two groups according to years since menopause (YSM) there were significant differences in LP and NTx between women <4 YSM and women aged <40 and those women aged 41+ (P < 0.01 and P < 0.05, respectively). A significant 110% increase in urinary NTx and a 48% increase in urinary LP were observed in postmenopausal women compared with age-matched premenopausal women aged 45–55. All biochemical markers other than serum PTH correlated significantly with each other (r = 0.243–0.858, P < 0.05–0.0001). Urinary NTx inversely correlated with lumbar spine BMD. When postmenopausal women were divided into three groups, the correlation between bone resorption and formation markers in women 0-1 YSM was greater than in women 2–10 YSM and in women 11 + YSM, indicating that resorption and formation are coupled at the early postmenopausal period. We conclude that urinary NTx is responsive to changes in bone metabolism caused by estrogen deficiency and may be a more sensitive and specific marker than HP, LP, or OH-Pr in the early postmenopausal years. Received: 15 February 1995 / Accepted: 18 October 1996     

Association Between Female Sex Hormones and Biochemical Markers of Bone Turnover in Peri- and Postmenopausal Women

In an epidemiological study, markers of bone formation (serum osteocalcin and C-terminal propeptide of type I collagen) and bone resorption [urinary type I collagen peptides (Crosslaps), urinary total pyridinoline (TPYRI), urinary deoxypyridinoline (DPYRI) as well as female sex hormones (serum estradiol)], follicle-stimulating hormone (FSH) and luteinizing hormone were measured in 237 women. This cohort aged 44–66 years, came for their first medical examination since menopause to the outpatient menopause clinic at the Kaiser-Franz-Josef-Hospital, Vienna. The women were all 0.5–5.0 years since cessation of menses and were not taking medications other than hormone replacement therapy [52 cases, 21.9%)] and had no diseases known to affect bone and mineral metabolism. The best correlation was found between urinary DPYRI and urinary TPYRI (r = 0.63, P= 0.0001), followed by urinary Crosslaps and urinary DPYRI (r = 0.47, p = 0.0001). Only weak but significant correlations between E₂ and urinary Crosslaps (r =−0.21, P < 0.0001) as well as serum E₂ and serum osteocalcin (r =−0.16, P= 0.0007), were observed. Of the 237 women 53% suffered from a severe E₂ deficiency (E₂ < 10.0 ng/liter). In these patients, urinary Crosslaps (+48%) and serum osteocalcin (+22%) were significantly higher (P < 0.0001) compared with those patients with E₂ levels > 10 ng/liter. Women with E₂ levels >10 ng/liter were further subdivided into those with and without sex hormone replacement therapy, whereby no statistical differences in any of the biochemical markers could be observed between these groups. We could clearly demonstrate that in postmenopausal women suffering from severe E₂ deficiency (E₂ < 10 ng/liter), urinary Crosslaps and serum osteocalcin are significantly increased, indicating in principle a clear correlation between E₂ deficiency and these markers of bone turnover. Received: 3 February 1997 / Accepted: 15 October 1997     

Chronology of renal scarring in males with Alport syndrome

We investigated the onset of renal scarring in 62 males (aged 4 – 26 years) with Alport syndrome by measuring cortical interstitial volume fraction [Vv (interstitium/cortex)] and percentage global glomerular sclerosis in kidney biopsies. Male pediatric (n = 9) and adult (n = 7) donor kidneys served as controls. Creatinine clearance at the time of biopsy was available for 43 Alport patients. A statistically insignificant correlation between age and Vv (interstitium/cortex) was observed in normal subjects (r = +0.47, slope = 0.0009, P = 0.07). In the Alport patients, age was significantly correlated with Vv (interstitium/cortex (r = +0.49, slope = 0.01, P = 0.001) and global glomerular sclerosis (r = +0.41, P = 0.01), and inversely correlated with creatinine clearance (r = –0.33, P = 0.04). Creatinine clearance was inversely correlated with Vv (interstitium/cortex) (r = –0.78, P = 0.001) and global glomerular sclerosis (r = –0.74, P = 0.001). The correlation with creatinine clearance was especially strong for Vv (interstitium/cortex) values above the normal range, i. e., >0.2 (r = –0.82, P = 0.001), and was absent for Vv (interstitium/cortex) <0.2 (r = –0.119, P = 0.55). Creatinine clearance values less than 80 ml/min per 1.73 m² occurred more frequently in patients with Vv (interstitium/cortex) values >0.2 (P <0.0001) and in patients with >10% globally sclerosed glomeruli (P <0.001). Patients ≤ or >10 years of age differed in Vv (interstitium/cortex) [0.13±0.09 (mean ±SD) vs. 0.24±0.026, P <0.001], the frequency of Vv (interstitium/cortex) >0.2 (3/32 vs. 15/31, P <0.0001), the frequency of >10% globally sclerosed glomeruli (3/33 vs. 11/30, P <0.05), mean creatinine clearance (113±7 vs. 84±10 ml/min per 1.73 m², P = 0.057), and the frequency of creatinine clearance <80 ml/min per 1.73 m² (1/20 vs. 11/23, P <0.01). Thus, reduced creatinine clearance in males with Alport syndrome is associated with Vv (interstitium/cortex) >0.2 and >10% globally sclerosed glomeruli. These are frequently detectable in the 2nd decade. We hypothesize that most Alport males will require intervention during the 1st decade for optimal preservation of kidney function. Received July 7, 1997; received in revised form October 23, 1997; accepted October 26, 1997     

The influence of ghrelin, adiponectin, and leptin on bone mineral density in healthy postmenopausal women

The association of body fat mass (FM) with bone mineral mass (BMC) and bone mineral density (BMD) has been attributed to a mechanical load exerted on the skeleton by FM and by the effect of different hormones. The aim of the present study was to determine whether there is a relationship between ghrelin, adiponectin, and leptin with BMC and BMD in healthy postmenopausal women (n = 88; age, 68.9 ± 6.8 years; body mass index, 27.4 ± 3.6 kg/m²). Body composition, BMC, and BMD were derived by dualenergy X-ray absorptiometry. Waist-to-hip (WHR) and waist-to-thigh (WTR) ratios were also obtained. Ghrelin was associated with total BMC (β = −0.945; P = 0.0001), total BMD (β = −0.959; P = 0.0001), lumbar spine BMD (β = −0.945; P = 0.0001), and femoral neck BMD (β = −0.957; P = 0.0001), and remained associated (P < 0.041) in different analyses that controlled for measured body composition and hormonal and insulin resistance values. However, the associations between ghrelin and measured bone mineral values were no longer significant (P > 0.149) when adjusted for body fat distribution values (WHR, WTR). Adiponectin was significantly related to total BMC (β = −0.931; P = 0.0001), total BMD (β = −0.940; P = 0.0001), lumbar spine BMD (β = −0.937; P = 0.0001), and femoral neck BMD (β = −0.940; P = 0.0001) values, and these relationships remained significant (P < 0.019) after adjusting for measured body fat, hormonal, and insulin resistance values but not when adjusted for fat-free mass (FFM; P > 0.106). In addition, significant associations of leptin with total BMC (β = 0.912; P = 0.0001), total BMD (β = 0.907; P = 0.0001), lumbar spine BMD (β = 0.899; P = 0.0001), and femoral neck BMD (β = 0.906; P = 0.0001) were found. These associations remained significant (P < 0.010) in different analyses that controlled for hormonal and insulin resistance values, but the associations between leptin and bone mineral values were no longer significant (P > 0.145) when adjusted for specific body composition values (WHR, WTR, FM, and FFM). In conclusion, it appears that the influence of plasma ghrelin, adiponectin, and leptin levels on BMC and BMD values is mediated or confounded by the specific body composition parameters in healthy postmenopausal women.     

Effects of sodium bicarbonate supplementation on axial and peripheral bone mass in rats on strenuous treadmill training exercise

We observed the effects of sodium bicarbonate supplement on bone mass in rats on strenuous treadmill training. Sixty female Wistar rats (93-days-old; mean initial weight 261 ± 16 g) were studied. One group of 15 rats was killed at the beginning of the experiments (basal control group), while another group of 15 rats was not manipulated (Exer−NaB−). Another group of 15 rats was exercised but did not receive sodium bicarbonate (Exer+NaB−), while the final group of 15 rats exercised and received sodium bicarbonate (Exer+NaB+) at a dose of 0.05 mg/kg/day, administered by esophageal catheter on exercise days. These rats were killed at the end of 11 weeks. Femoral and vertebral length, weight, and bone mineral content (BMC) and density (BMD) were measured. According to anova with the Tukey–Kramer test, femur length and weight, vertebral weight, femur BMC and BMD, vertebral BMC and BMD and the ratio between femur and vertebral BMC and final body weight, and plasma bicarbonate were lower in the basal control and Exer+NaB− groups than in the two other groups (P < 0.005–0.0001). Overall, there was a positive correlation between femur and vertebral BMC and femur BMC and length (P < 0.0001 for all). Only in the Exer+NaB− group was there a positive association between plasma bicarbonate levels and femur length (r = 0.78; P < 0.0005). Our study demonstrates the adverse effects of strenuous exercise on bone, and the usefulness of sodium bicarbonate supplements in preventing and minimized these effects. Received: May 1, 2000 / Accepted: August 11, 2000     

Ascorbic Acid Deficiency, Iron Overload and Alcohol Abuse Underlie the Severe Osteoporosis in Black African Patients with Hip Fractures — A Bone Histomorphometric Study

Osteoporosis and femoral neck fractures (FNF) are uncommon in black Africans although osteoporosis accompanying iron overload (from traditional beer brewed in iron containers) associated with ascorbic acid deficiency (oxidative catabolism by iron) has been described from sub-Saharan Africa. This study describes histomorphometric findings of iliac crest bone biopsies and serum biochemical markers of iron overload and of alcohol abuse and ascorbic acid levels in 50 black patients with FNFs (29 M, 21 F), age 62 years (40–95) years (median [min-max]), and in age- and gender-matched black controls. We found evidence of iron overload in 88% of patients and elevated markers of alcohol abuse in 72%. Significant correlations between markers of iron overload and of alcohol abuse reflect a close association between the two toxins. Patients had higher levels of iron markers, i.e., siderin deposits in bone marrow (P < 0.0001), chemical non-heme bone iron (P = 0.012), and serum ferritin (P = 0.017) than controls did. Leukocyte ascorbic acid levels were lower (P = 0.0008) than in controls. The alcohol marker mean red blood cell volume was elevated (P = 0.002) but not liver enzymes or uric acid. Bone volume, trabecular thickness, and trabecular number were lower, and trabecular separation was greater in patients than in controls, all at P < 0.0005; volume, surface, and thickness of osteoid were lower and eroded surface was greater, all at P < 0.0001. There was no osteomalacia. Ascorbic acid deficiency accounted significantly for decrease in bone volume and trabecular number, and increase in trabecular separation, osteoid surface, and eroded surface; iron overload accounted for a reduction in mineral apposition rate. Alcohol markers correlated negatively with osteoblast surface and positively with eroded surface. Relative to reported data in white FNF patients, the osteoporosis was more severe, showed lower osteoid variables and greater eroded surface; FNFs occurred 12 years earlier and were more common among men. We conclude that the osteoporosis underlying FNFs in black Africans is severe, with marked uncoupling of resorption and formation in favor of resorption. All three factors—ascorbic acid deficiency, iron overload, and alcohol abuse—contributed to the osteoporosis, in that order.     

Measurement of bone mineral density of lumbar spine and whole body in low-birth-weight infants: comparison of two methods

In the present study, we compared lumbar spinal and whole-body bone mineral density (BMD) measurements to determine which is more suitable for evaluating the bone mineral status of low-birth-weight (LBW) infants. Lumbar spinal and whole-body BMD were assessed simultaneously in a prospective series including 152 Japanese LBW infants (birth weight 453–2400 g, gestational age 24–38 weeks) from the age of 40 weeks post-conception to 2 years of age. Lumbar spinal BMD at 40 weeks post-conception was significantly correlated with birth weight (r = 0.74; P < 0.0001), but whole-body BMD was not correlated with birth weight. No correlation was found between lumbar spinal and whole-body BMD at 40 weeks post-conception. However, after 40 weeks post-conception, a significant correlation was found between lumbar spinal and whole-body BMD (r = 0.65; P < 0.0001). For infants with a body weight of 4 kg or less at the time of measurement, no correlation was found between lumbar spinal and whole-body BMD. However, for infants with a body weight above 4 kg, a significant correlation was found between lumbar spinal and whole-body BMD (r = 0.65; P < 0.0001). Thus, lumbar spinal BMD is more suitable than whole-body BMD for evaluation of the bone mineral status of LBW in early infancy. Therefore, lumbar spinal BMD should be used for serial evaluation of changes in the bone mineral status of LBW infants. Received: April 6, 2000 / Accepted: June 16, 2000     

A quantitative study of iliac bone histopathology on 62 cases with itai-itai disease

Summary Sixty-two autopsy cases with “itai-itai” or “ouch-ouch” (in English) disease and 50 control subjects were examined by static quantitative bone histopathology. Decalcified sections after cyanuric chloride treatment (Yoshiki's method) [5–7] were used. The small observer variances of the decalcified sections guaranteed the accuracy and precision of this method. In the static measurement analyses, significant increases in formation parameters and decreases in structural parameters were observed (P<0.05–0.000001), suggesting the presence of a marked osteoid accumulation accompanied by a bone mass reduction. Discriminant analysis clearly separated the patients from the control subjects. Two-thirds of the patients showed an increase in resorption surface prior to osteoid deposition and a decrease in osteoblast surface. Double tetracycline labeling in 4 patients showed an impaired osteoid maturation and mineralization. An impaired osteoblastic function was suggested by the results of the static and dynamic histomorphometry. The bone cadmium contents were measured in 46 patients by an atomic absorption spectrophotometer and found to be increased significantly (P<0.01). In Aluminon (an ammonium salt of aurine tricarboxytic acid) staining, a clear, reddish line was located in an osteoid-bone interface, suggesting a reaction of Aluminon with tissue aluminium and/or cadmium. These results suggested that an impairment of osteoblastic function and mineralization occurred in itai-itai disease and that cadmium is a possible etiological factor.     

Loss of Bone Mineral Density in Women Athletes During Aging

Total and regional bone mineral density (BMD) by dual-energy-X-ray absorptiometry (DXA) and bone turnover were tested in 50 highly trained women athletes and 21 sedentary control women (18–69 years; BMI < 25 kg/m²). VO_2max (ml · kg⁻¹· min⁻¹) and lean tissue mass (DXA) were significantly higher in the athletes versus controls (both P < 0.0001). Total body BMD did not decline significantly with age in the athletes whereas lumbar spine (L₂–L₄) BMD approached statistical significance (r =−0.26; P= 0.07). Significant losses of the femoral neck (r =− 0.42), Ward's triangle (r =−0.53), and greater trochanter BMD (r =−0.33; all P < 0.05) occurred with age in the athletes. In the athletes, total body BMD, L₂–L₄ BMD, and BMD of all sites of the femur were associated with lean tissue mass (r = 0.32 to r = 0.57, all P < 0.05) and VO_2max (r = 0.29 to r = 0.48, all P < 0.05). Femoral neck and greater trochanter BMD were higher in the athletes than in controls (both P < 0.05) and lumbar spine and Ward's triangle BMD approached statistical significance (both P= 0.07). Bone turnover was assessed by serum bone-specific alkaline phosphatase (B-ALP), urinary deoxypyridinoline cross-links (Dpd), and urinary aminoterminal cross-linked telopeptides (NTX). There were no relationships between B-ALP or Dpd with age whereas NTX increased with age (r = 0.46, P < 0.05) in the entire group. Levels of B-ALP and NTX were negatively associated with total body, L₂–L₄, femoral neck, Ward's triangle, and greater trochanter BMD (P < 0.05). B-ALP and Dpd were not significantly different between athletes and controls whereas NTX was lower in the athletes than in controls (P < 0.001). The high levels of physical activity observed in women athletes increase aerobic capacity and improve muscle mass but are not sufficient to prevent the loss of bone with aging. Received: 28 November 1997 / Accepted: 8 April 1998     

Adaptations in the Mandible and Appendicular Skeleton of High and Low Bone Density Inbred Mice

The appendicular skeletons of high [C3H/HeJ (C3H)] and low [C57BL/6J (B6)] density inbred mice have been shown to differ in morphology, mechanical properties, and cellular activity. The focus of the current study was to (1) characterize the mandibular bone formation rate (BFR/BS), bone mass, indentation modulus (IM), and hardness of C3H and B6 mice and (2) investigate the relationship of the mechanical properties in three skeletal sites: mandible, femur, and tibia. Specimens from 17-week-old female C3H and B6 (n = 15/group) mice were obtained. Mandibular bone mass was estimated from the lateral-view area (LVA) and transverse cross sections. BFR/BS was measured in the mandibular section distal to the third molar. In addition, bone blocks from the distal surface of the third molar and the femoral and tibial midshaft were obtained for mechanical testing. BFR/BS, cortical area, and LVA were greater (P < 0.001) in C3H mandibles. IM was approximately 2 GPa higher in the C3H mandible (P > 0.05), femur (P < 0.001), and tibia (P < 0.01). Mandibular IM was lower (P < 0.05) than the femoral and tibial IM within each inbred mouse. IM was not significant between C3H and B6 mandibles. However, the magnitude of the difference (∼12%) in the mandible was similar to the difference in the appendicular skeleton. This mandibular bone phenotype is similar to that observed in the appendicular skeleton of these distinct inbred mice.     

Ultrasonographic, Axial, and Peripheral Measurements in Female Patients with Benign Hypermobility Syndrome

Twenty-five female Caucasians, aged 19–57 years, with the hypermobility syndrome had bone density measurements using established noninvasive techniques such as dual X-ray absorptiometry (DXA), single photon absorptiometry (SPA), heel ultrasound (US), and peripheral computed tomography (pQCT) acquisitions of the radius. As a group, comparisons of the different bone indices with the corresponding age-matched reference population resulted in normal z-scores for the arial densities, however, values for the volumetric total and cortical bone at the radius measured by pQCT were significantly lower than expected (P < 0.0001). Spinal and femoral bone density results were significant after correction for body mass index (BMI). This cross-sectional study shows that the benign hypermobility syndrome patients have lowered t-scores for data reflecting bone structure and bone strength as measured with US and the tomographic technique. Received: 8 May 1999 / Accepted: 21 January 2000     

High Osteoblastic Activity In C3H/HeJ Mice Compared to C57BL/6J Mice Is Associated with Low Apoptosis in C3H/HeJ Osteoblasts

This study sought to confirm that osteoblasts of C3H/HeJ (C3H) mice, which have higher differentiation status and bone-forming ability compared to C57BL/6J (B6) osteoblasts, also have a lower apoptosis level and to test whether the higher differentiation status and bone-forming ability of C3H osteoblasts were related to the lower apoptosis. C3H mice had 50% fewer (P < 0.01) apoptotic osteoblasts on the endocortical bone surface than B6 mice as determined by the TUNEL assay. Primary C3H osteoblasts in cultures also showed a 50% (P < 0.05) lower apoptosis level than B6 osteoblasts assayed by acridine orange/ethidium bromide staining of apoptotic osteoblasts. The lower apoptosis in C3H osteoblasts was accompanied by 22% (P < 0.05) and 56% (P < 0.001) reduction in the activity of total caspases and caspases 3/7, respectively. C3H osteoblasts also displayed greater alkaline phosphatase (ALP) activity (P < 0.001) and higher expression of Cbfa1, type-1 collagen, osteopontin, and osteocalcin genes (P < 0.05 for each). To assess if an association existed between population apoptosis and the differentiation status (ALP-specific activity) and/or bone-forming activity (insoluble collagen synthesis), C3H and B6 osteoblasts were treated with several apoptosis enhancers (tumor necrosis factor-α, dexamethasone, lipopolysaccharide, etoposide) and inhibitors (parathyroid hormone, insulin-like growth factor I, transforming growth factor β1, estradiol). Both ALP (r = −0.61, P < 0.001) and insoluble collagen synthesis (r = −0.61, P < 0.001) were inversely correlated with apoptosis, suggesting that differentiation (maturation) and/or bone-forming activity of these mouse osteoblasts were inversely associated with apoptosis. In conclusion, these studies support the premise that higher bone density and bone formation rate in C3H mice could be due in part to lower apoptosis in C3H osteoblasts.     

Aged mice have enhanced endocortical response and normal periosteal response compared with young‐adult mice following 1 week of axial tibial compression

With aging, the skeleton may lose its ability to respond to positive mechanical stimuli. We hypothesized that aged mice are less responsive to loading than young‐adult mice. We subjected aged (22 months) and young‐adult (7 months) BALB/c male mice to daily bouts of axial tibial compression for 1 week and evaluated cortical and trabecular responses using micro–computed tomography (µCT) and dynamic histomorphometry. The right legs of 95 mice were loaded for 60 rest‐inserted cycles per day to 8, 10, or 12 N peak force (generating mid‐diaphyseal strains of 900 to 1900 µε endocortically and 1400 to 3100 µε periosteally). At the mid‐diaphysis, mice from both age groups showed a strong anabolic response on the endocortex (Ec) and periosteum (Ps) [Ec.MS/BS and Ps.MS/BS: loaded (right) versus control (left), p < .05]. Generally, bone formation increased with increasing peak force. At the endocortical surface, contrary to our hypothesis, aged mice had a significantly greater response to loading than young‐adult mice (Ec.MS/BS and Ec.BFR/BS: 22 months versus 7 months, p < .001). Responses at the periosteal surface did not differ between age groups (p > .05). The loading‐induced increase in bone formation resulted in increased cortical area in both age groups (loaded versus control, p < .05). In contrast to the strong cortical response, loading only weakly stimulated trabecular bone formation. Serial (in vivo) µCT examinations at the proximal metaphysis revealed that loading caused a loss of trabecular bone in 7‐month‐old mice, whereas it appeared to prevent bone loss in 22‐month‐old mice. In summary, 1 week of daily tibial compression stimulated a robust endocortical and periosteal bone‐formation response at the mid‐diaphysis in both young‐adult and aged male BALB/c mice. We conclude that aging does not limit the short‐term anabolic response of cortical bone to mechanical stimulation in our animal model. © 2010 American Society for Bone and Mineral Research