Bone histology in young adult osteoporosis

Hyaluronan in immune dysregulation and autoimmune diseases

The tissue microenvironment contributes to local immunity and to the pathogenesis of autoimmune diseases - a diverse set of conditions characterized by sterile inflammation, immunity against self-antigens, and destruction of tissues. However, the specific factors within the tissue microenvironment that contribute to local immune dysregulation in autoimmunity are poorly understood. One particular tissue component implicated in multiple autoimmune diseases is hyaluronan (HA), an extracellular matrix (ECM) polymer. HA is abundant in settings of chronic inflammation and contributes to lymphocyte activation, polarization, and migration. Here, we first describe what is known about the size, amount, and distribution of HA at sites of autoimmunity and in associated lymphoid structures in type 1 diabetes, multiple sclerosis, and rheumatoid arthritis. Next, we examine the recent literature on HA and its impact on adaptive immunity, particularly in regards to the biology of lymphocytes and Foxp3+ regulatory T-cells (Treg), a T-cell subset that maintains immune tolerance in healthy individuals. We propose that HA accumulation at sites of chronic inflammation creates a permissive environment for autoimmunity, characterized by CD44-mediated inhibition of Treg expansion. Finally, we address potential tools and strategies for targeting HA and its receptor CD44 in chronic inflammation and autoimmunity.

In vivo loading model to examine bone adaptation in humans: a pilot study

Bone is typically well suited for its habitual loading environment because of its ability to adapt. Although characteristics of the mechanical loading environment predict the bone adaptive response in animals, this has not been prospectively validated in humans. Here, we describe an in vivo loading model in which women apply forces to the radius by leaning onto their hand. We characterized the strain environment imposed on the radius using cadaveric experimentation and conducted a prospective study in which 19 adult women loaded their distal radii 50 cycles/day, 3 days/week, for 28 weeks and seven additional adult women served as controls. In four cadaveric specimens, loading caused compressive principal strains of -1,695 ± 396 με with radial bending dorsally and towards the ulna. Prospective in vivo loading produced measurable improvements to bone and appeared to protect against bone loss associated with seasonal fluctuations in physical activity and sun exposure. Experimental subjects had significant gains to bone volume (BV) and moments of inertia, while, control subjects had significant losses in BMC and moments of inertia. The loading model is thus suitable as a model system for exploring bone adaptation in humans, and may eventually be clinically useful for strengthening the radius of women.

Effects of physical training on bone mineral density in fertile women with idiopathic osteoporosis

The aim of this study was to investigate whether moderate physical training can improve the bone mineral density (BMD) in women with idiopathic osteoporosis. Ten pre-menopausal women aged 24-44 years diagnosed with idiopathic osteoporosis were included in the study. The physical training program consisted of three fast 30-min walks plus one or two sessions of 1-h training per week during 1 year at a training centre separate from the hospital. All patients were given supplements of vitamin D and calcium. Bone mineral density was measured in the femoral neck area and the lumbar spine by dual energy X-ray absorptiometry. The measurements were performed at baseline and after 12 months of training and compared with the measurements at the time of diagnosis, 1-3 years before the study. Eight women fulfilled the 12-month training period, and their mean (SD) BMD at start was 0.88 (0.08) g/cm(2) in the spine and 0.76 (0.13) g/cm(2) in the femoral neck. The mean spine BMD increase was 0.031 g/cm(2) (3.5%) after 1 year of training, which was significant (Wilcoxon's non-parametric test, p = 0.018). The mean increment in BMD in the femoral neck was insignificant, 0.007 g/cm(2) (0.9%) after the intervention (p = 0.74). However, the bone loss during the 1- to 3-year period from diagnosis to study start was, on average, 0.045 g/cm(2) or 5.0% in the femoral neck (p = 0.042), thus indicating a positive indirect effect of the intervention. There is no evidence-based therapy for women with idiopathic osteoporosis. It is therefore of importance to elucidate the impact of moderate physical activity in this group of patients. A 1-year training program was sufficient to induce a small but significant change in the spine BMD.

Bone turnover markers and sex hormones in men with idiopathic osteoporosis

BACKGROUND

In contrast to osteoporosis in postmenopausal women, osteoporosis in men has received much less attention.

PATIENTS AND METHODS

We determined various biochemical parameters of bone metabolism and sex hormones in 31 men with idiopathic osteoporosis and 35 age matched control subjects.

RESULTS

In the men with osteoporosis, a significantly increased urinary excretion of deoxypyridinoline (5.3 +/- 0.2 vs. 4.6 +/- 0.2 nmol mmol-1 creatinine; P = 0.033) in addition to increased serum levels of the c-terminal telopeptide of type I collagen (2677 +/- 230 vs. 2058 +/- 153 pmol; P = 0.037) were found. While parameters of bone formation were not significantly different in the patients and controls, serum bone sialoprotein levels were significantly decreased in the patients (3.7 +/- 0.8 vs. 12.4 +/- 4.0 ng mL-1; P = 0.021). Moreover, in men with idiopathic osteoporosis, lower levels of estradiol (91.3 +/- 5.8 vs. 114.6 +/- 7.8 pmol L-1; P = 0.044), higher levels of sex hormone binding globulin (31.5 +/- 3.1 vs. 24.2 +/- 1.4 nmol L-1; P = 0.034) and a decreased free androgen index (42.6 +/- 5.2 vs. 56.4 +/- 5.9; P = 0.016) were seen. Serum estradiol levels correlated negatively with several parameters of bone resorption.

CONCLUSIONS

In men with idiopathic osteoporosis, bone resorption is increased and exceeds bone formation. The excessive bone resorption seen in idiopathic male osteoporosis may be due to decreased estradiol levels and low levels of bioavailable testosterone.

Age-related changes in bone density among healthy Greek males

Osteoporosis in men is increasingly recognized as a problem in clinical medicine, but it has received much less attention than its counterpart in women. It is termed idiopathic if no known cause of bone disease can be identified clinically or in the laboratory. The true incidence of idiopathic osteoporosis (IO) in males is difficult to estimate because population characteristics and referral patterns differ so widely. The aim of this study was to investigate the incidence of IO in healthy Greek male volunteers by measuring bone mineral density (BMD) at four skeletal sites and examining the relations among age, BMI, and bone status. This type of information has not yet been published. We considered osteoporosis to be present when the BMD was less than or equal to -2.5 SD from the average value for healthy young men. Three hundred and sixty-three normal male volunteers were investigated. The mean age was 51.3+/-8.7 yr, and BMI was 27.5+/-3.7 kg/m2. In all subjects BMD at four skeletal sites - lumbar spine (LS), femoral neck (FN), Ward's triangle (WT), and finally trochanter (T) - was measured using dual-energy X-ray absorptiometry (DEXA). T-score, Z-score and g/cm2 values were estimated. Forty-four subjects (11%) had BMD< or =-2.5 SD (T-score). The mean age and BMI for the men with decreased BMD was 54.8+/-6.4 yr and 26.3+/-3.3 kg/m2, whereas mean age and BMI for those with normal BMD was 51.0+/-8.9 yr and 27.6+/-3.6 kg/m2, respectively. These differences were statistically significant (p<0.001 and p<0.05, respectively). A positive correlation was found between BMI and bone density (g/cm2) at three skeletal sites: LS (r=0.235, p<0.001), WT (r=0.126, p<0.001) and FN (r=0.260, p<0.001). A positive correlation was also found between BMI and T-score at all skeletal sites studied: LS (r=0.276, p<0.001), WT (r=0.133, p<0.05), FN (r=0.233, p<0.001), and T (r=0.305, p<0.001). Finally, a positive correlation was also found between BMI and Z-score: LS (r=0.256, p<0.001), WT (r=0.117, p<0.005), FN (r=0.240, p<0.001), and T (r=0.187, p<0.001). A negative correlation was found between age and bone density (g/cm2) at FN (r=-0.157, p<0.01) and WT (r=-0.183, p<0.001). The same was true between age and T-score at FN only (r=0.137, p<0.05). Furthermore, a similar correlation was found between age and Z-score at LS (r=0.174, p<0.001). When ANOVA one-way analysis was used, a significant difference was found between the different age groups and BMD (g/cm2) at FN, T, and WT (p<0.001 for all sites). For T-score, a significant difference between age groups was found only at FN (p<0.005). Finally, a significant difference in Z-score was found at FN (p<0.001) and LS (p<0.005). When multiple regression analysis was applied, it was found that BMD (g/cm2) at two sites, FN and WT, independently correlated with age and BMI (FN: p<0.001 for both, WT: p<0.01 and p<0.05, respectively). Finally, we found an accelerated trend toward decreased BMD (g/cm2), when the odds ratio was applied. In conclusion, this study demonstrated that 11% of otherwise healthy Greek men had BMD less than or equal to -2.5 SD. A strong association was found between BMD (g/cm2) and age at three skeletal sites when ANOVA one-way analysis was applied. Moreover, BMD was positively correlated with BMI and negatively correlated with age. Currently available data are sparse and much more research is needed to increase our understanding concerning the etiology of this condition as well as illuminating the relationship between bone density and fracture.

Adaptive changes in trabecular architecture in relation to functional strain patterns and disuse

Principal strains and their orientation, determined from in vivo and in situ strains recorded from the lateral cortical surface of the calcaneus of potoroos (a small marsupial) during treadmill exercise and tension applied via the Achilles tendon, were compared with the underlying trabecular architecture and its alignment to test Wolff's "trajectorial theory" of trabecular alignment. In vivo and in situ principal compressive strains (-800 to -2000 mu e) were found to be aligned (mean 161 +/- 7 degrees) close to the preferred alignment (160 degrees) of underlying trabeculae within the calcaneal metaphysis [a second trabecular arcade was closely aligned (70 degrees) with the direction (71 degrees) of principal tensile strain]. This finding represents quantitative verification of Wolff's trajectorial theory of trabecular alignment. These trabecular alignments, as measured by trabecular anisotropy (TbAn, the ratio of horizontal: vertical intercepts), remained unchanged (p > 0.05) after 8 weeks of disuse. However, trabecular bone volume fraction (BV/TV, -35%), trabecular thickness (TbTh, -25%), and trabecular number (TbN, -16%) were reduced for the tenotomized calcaneii relative to their contralateral controls (p < 0.001 to < 0.003). The reduction in trabecular number was associated with a corresponding increase in trabecular spacing (TbSp, +30%). Together, these results suggest that once trabecular alignment is established during growth (along the directions of principal strain during locomotion), it is not altered when functional strains are removed.

Statistical analysis of compositional data in anatomy

BACKGROUND

Variables which describe the composition, or relative size of components, of an organism need to be analysed in an appropriate manner.

METHODS

A few of the appropriate descriptive and inferential techniques have been described and applied to a number of anatomical data sets.

RESULTS

When applied to data on the composition of the vastus medialis in adults, a small but significant difference in average muscle fibre type distribution was demonstrated between males and females. There was little evidence for a relationship between fibre type distribution and age over the range considered.

CONCLUSIONS

Graphical displays via ternary diagrams are a simple way of illustrating compositional data simultaneously between and within groups. Numerical analysis is likely to involve transformation of original variables before standard univariate or multivariate statistical techniques can be used.

Epidemiology and clinical features of osteoporosis in young individuals

Due to the lack of epidemiologic data on osteoporosis in the young, we identified all 22 Olmsted County, MN, residents aged 20-44 years when first diagnosed with established osteoporosis in 1976-1990. The overall age- and sex-adjusted incidence rate was 4.1 per 100,000 person-years (95% CI 2.4-5.9) with a female to male ratio of age-adjusted rates of 1.2:1. The majority represented secondary osteoporosis (12 steroid-induced, 3 postmenopausal, 2 delayed puberty, 2 anticonvulsant-induced, 2 gastrointestinal disease, 2 alcoholism, 1 anorexia nervosa, and 7 other etiologies; some individuals had more than one factor present) but two had idiopathic osteoporosis (incidence 0.4 per 100,000 person-years, 95% CI 0-0.9). To further characterize the patients with idiopathic osteoporosis, we also reviewed the entire Mayo Clinic experience with such patients from 1976 to 1990, regardless of residency. A total of 56 patients (30 female/26 male) were identified with a median age at diagnosis of 34 years. Only 8% were hypercalciuric at presentation. There was a preponderance of cancellous bone fractures (vertebral 81%, rib 37%, wrist 13%), although 13% did have hip fractures. Transiliac bone biopsies were available in 18 patients. As compared to age- and sex-matched controls, the osteoporotic subjects had a significant reduction in trabecular bone volume, cortical thickness, and mean wall thickness, the latter suggesting an abnormality in osteoblast function in these individuals.(ABSTRACT TRUNCATED AT 250 WORDS)

Aetiologies of male osteoporosis: identification procedures

Secondary causes and risk factors assume far greater importance in male osteoporosis than in female osteoporosis. The principal problem in dealing with male osteoporosis, above all in young men, is the difficulty to find a curable aetiology. Six groups of aetiologies can be drawn up: toxic causes or causes due to a change in the general state of health, drug-induced causes, renal causes, hormonal causes, exceptional causes and lastly the idiopathic form. The minimum number of investigations necessary so as to be quite sure not to overlook these various aetiologies is proposed.

Osteoporosis in longstanding acromegaly: characteristic changes of vertebral trabecular architecture and bone matrix composition

Although it is now 60 years after Erdheim's (1931) detailed description of vertebral alterations in severe acromegaly, it is still unclear whether osteoporosis is a consistent feature of acromegalic bone disease or not. We studied the vertebral trabecular bone of a 44-year-old woman who had suffered active acromegaly for more than 20 years, and compared it with 17 normal as well as 2 osteoporotic controls. Histomorphometry revealed a very low trabecular bone volume and thus documented the presence of osteoporosis. The mean trabecular plate thickness was strikingly increased in acromegaly (possibly caused in part by a low-dose fluoride treatment), whereas it was normal or reduced in the osteoporotic controls. The meticulous analysis showed islands of cartilaginous tissue in the core of the acromegalic trabeculae which were not present in any other sample. In these areas collagen II was detected by immunohistochemistry. Biochemical analysis revealed that collagen II accounted for 7% of the total collagenous matrix. The degree of hydroxylation of lysyl residues of collagen I was close to the average value of all control samples studied. Our data show that osteoporosis can occur in acromegaly and that it is characterized by unusual architectural and compositional features. These findings challenge the prevailing view that the matrix of osteoporotic bone always shows a normal composition.