Correlation between absence of bone remodeling compartment canopies, reversal phase arrest, and deficient bone formation in post-menopausal osteoporosis.

Bone remodeling compartments (BRCs) were recently recognized to be present in patients with primary hyperparathyroidism and critical for bone reconstruction in multiple myeloma and endogenous Cushing's syndrome. The BRCs are outlined by a cellular canopy separating the bone remodeling events on the bone surface from the marrow cavity. The present study on human iliac crest biopsy specimens reveals that BRC canopies appear frequently absent above both eroded and formative surfaces in post-menopausal osteoporosis patients, and that this absence was associated with bone loss in these patients. The absence of BRC canopies above the eroded surfaces was furthermore associated with the accumulation of arrested reversal surfaces and a reduced extent of formative surfaces, which both reflect an increased incidence of aborted remodeling cycles. Moreover, the absence of BRC canopies above formative surfaces was associated with a shift in the osteoblast morphological characteristics, from cuboidal to flattened. Collectively, this study shows that the BRCs are unique anatomical structures implicated in bone remodeling in a widespread disease, such as post-menopausal osteoporosis. Furthermore, it particularly highlights the role of the BRC canopies to make the reversal phase progressing toward initiation of matrix deposition, thereby preventing bone loss.

Understanding coupling between bone resorption and formation: are reversal cells the missing link?

Bone remodeling requires bone resorption by osteoclasts, bone formation by osteoblasts, and a poorly investigated reversal phase coupling resorption to formation. Likely players of the reversal phase are the cells recruited into the lacunae vacated by the osteoclasts and presumably preparing these lacunae for bone formation. These cells, called herein reversal cells, cover >80% of the eroded surfaces, but their nature is not identified, and it is not known whether malfunction of these cells may contribute to bone loss in diseases such as postmenopausal osteoporosis. Herein, we combined histomorphometry and IHC on human iliac biopsy specimens, and showed that reversal cells are immunoreactive for factors typically expressed by osteoblasts, but not for monocytic markers. Furthermore, a subpopulation of reversal cells showed several distinctive characteristics suggestive of an arrested physiological status. Their prevalence correlated with decreased trabecular bone volume and osteoid and osteoblast surfaces in postmenopausal osteoporosis. They were, however, virtually absent in primary hyperparathyroidism, in which the transition between bone resorption and formation occurs optimally. Collectively, our observations suggest that arrested reversal cells reflect aborted remodeling cycles that did not progress to the bone formation step. We, therefore, propose that bone loss in postmenopausal osteoporosis does not only result from a failure of the bone formation step, as commonly believed, but also from a failure at the reversal step.

Taper versus discontinuation of tocilizumab in patients with giant cell arteritis: Real-world experience from a tertiary center.

INTRODUCTION: Following the approval of tocilizumab (TCZ) for giant cell arteritis (GCA), recent studies have shown a high relapse frequency after abrupt discontinuation of TCZ. However, a thorough exploration of TCZ tapering compared to abrupt discontinuation has never been undertaken. Likewise, adverse events have only been scarcely investigated in routine care. This study aimed to compare the incidence of relapses in GCA patients undergoing TCZ tapering compared to abrupt discontinuation. METHODS: We performed a single-center retrospective cohort study from 2012 to 2022. Data from GCA patients treated with TCZ was obtained from the Electronic Patients Record. Relapse-free survival is reported in Kaplan-Meier plots and tapering versus abrupt discontinuation were compared using a Wilcoxon-Brewlos-Gehan test. RESULTS: We included 155 patients receiving TCZ treatment for GCA, of which 104 discontinued TCZ. Among the 104 patients discontinuing TCZ, 42 (40 %) experienced a relapse within the first year. A total of 57 patients underwent taper with 6/38 (16 %) and 2/19 (11 %) relapsing while receiving TCZ every second or third week, respectively. In comparison, 59 patients underwent abrupt discontinuation with 27 (46 %) relapsing during follow-up. The patients undergoing abrupt TCZ discontinuation demonstrated a significantly shorter time to relapse compared to all tapered patients (p = 0.02) as well as patients tapered from weekly TCZ treatment to every second week (p < 0.01). Furthermore, 15 % of patients discontinued TCZ due to adverse events. CONCLUSION: This is the first study indicating that TCZ taper induced longer relapse-free survival than abrupt discontinuation, implying that taper may be favored over discontinuation in patients with GCA.

Atherosclerotic Cardiovascular Risk Stratification in the Rheumatic Diseases:: An Integrative, Multiparametric Approach.

Cardiovascular disease (CVD) risk is increased in most inflammatory rheumatic diseases (IRDs), reiterating the role of inflammation in the initiation and progression of atherosclerosis. An inverse association of CVD risk with body weight and lipid levels has been described in IRDs. Coronary artery calcium scores, plaque burden and characteristics, and carotid plaques on ultrasound optimize CVD risk estimate in IRDs. Biomarkers of cardiac injury, autoantibodies, lipid biomarkers, and cytokines also improve risk assessment in IRDs. Machine learning and deep learning algorithms for phenotype and image analysis hold promise to improve CVD risk stratification in IRDs.

Disturbed bone marrow adiposity in patients with Cushing's syndrome and glucocorticoid- and postmenopausal- induced osteoporosis.

Background: Skeletal stem/progenitor cells (SSPCs) in the bone marrow can differentiate into osteoblasts or adipocytes in response to microenvironmental signalling input, including hormonal signalling. Glucocorticoids (GC) are corticosteroid hormones that promote adipogenic differentiation and are endogenously increased in patients with Cushing´s syndrome (CS). Here, we investigate bone marrow adiposity changes in response to endogenous or exogenous GC increases. For that, we characterize bone biopsies from patients with CS and post-menopausal women with glucocorticoid-induced osteoporosis (GC-O), compared to age-matched controls, including postmenopausal osteoporotic patients (PM-O). Methods: Transiliac crest bone biopsies from CS patients and healthy controls, and from postmenopausal women with GC-O and matched controls were analysed; an additional cohort included biopsies from women with PM-O. Plastic-embedded biopsies were sectioned for histomorphometric characterization and quantification of adipocytes. The fraction of adipocyte area per tissue (Ad.Ar/T.Ar) and marrow area (Ad.Ar/Ma.Ar), mean adipocyte profile area (Ad.Pf.Ar) and adipocyte profile density (N.Ad.Pf/Ma.Ar) were determined and correlated to steroid levels. Furthermore, the spatial distribution of adipocytes in relation to trabecular bone was characterized and correlations between bone marrow adiposity and bone remodeling parameters investigated. Results: Biopsies from patients with CS and GC-O presented increased Ad.Ar/Ma.Ar, along with adipocyte hypertrophy and hyperplasia. In patients with CS, both Ad.Ar/Ma.Ar and Ad.Pf.Ar significantly correlated with serum cortisol levels. Spatial distribution analyses revealed that, in CS, the increase in Ad.Ar/Ma.Ar near to trabecular bone (<100 µm) was mediated by both adipocyte hypertrophy and hyperplasia, while N.Ad.Pf/Ma.Ar further into the marrow (>100 µm) remained unchanged. In contrast, patients with GC-O only presented increased Ad.Ar/Ma.Ar and mean Ad.Pf.Ar>100 µm from trabecular bone surface, highlighting the differential effect of increased endogenous steroid accumulation. Finally, the Ad.Ar/Ma.Ar and Ad.Ar/T.Ar correlated with the canopy coverage above remodeling events. Conclusion: Increased cortisol production in patients with CS induces increased bone marrow adiposity, primarily mediated by adipocyte hypertrophy. This adiposity is particularly evident near trabecular bone surfaces, where hyperplasia also occurs. The differential pattern of adiposity in patients with CS and GC-O highlights that bone marrow adipocytes and their progenitors may respond differently in these two GC-mediated bone diseases.

The combination of structural parameters and areal bone mineral density improves relation to proximal femur strength: an in vitro study with high-resolution peripheral quantitative computed tomography.

The aim of this study was to assess structural indices from high-resolution peripheral quantitative computed tomography (HR-pQCT) images of the human proximal femur along with areal bone mineral density (aBMD) and compare the relationship of these parameters to bone strength in vitro. Thirty-one human proximal femur specimens (8 men and 23 women, median age 74 years, range 50-89) were examined with HR-pQCT at four regions of interest (femoral head, neck, major and minor trochanter) with 82 µm and in a subgroup (n = 17) with 41 µm resolution. Separate analyses of cortical and trabecular geometry, volumetric BMD (vBMD), and microarchitectural parameters were obtained. In addition, aBMD by dual-energy X-ray absorptiometry (DXA) was performed at conventional hip regions and maximal compressive strength (MCS) was determined in a side-impact biomechanical test. Twelve cervical and 19 trochanteric fractures were confirmed. Geometry, vBMD, microarchitecture, and aBMD correlated significantly with MCS, with Spearman's correlation coefficients up to 0.77, 0.89, 0.90, and 0.85 (P < 0.001), respectively. No differences in these correlations were found using 41 µm compared to 82 µm resolution. In multiple regression analysis of MCS, a combined model (age- and sex-adjusted) with aBMD and structural parameters significantly increased R (2) values (up to 0.90) compared to a model holding aBMD alone (R (2) up to 0.78) (P < 0.05). Structural parameters and aBMD are equally related to MCS, and both cortical and trabecular structural parameters obtained from HR-pQCT images hold information on bone strength complementary to that of aBMD.

Association between condylar morphology and changes in bony microstructure and sub-synovial inflammation in experimental temporomandibular joint arthritis.

BACKGROUND: In juvenile idiopathic arthritis involvement of the temporomandibular joints (TMJs) is often associated with mandibular growth deviations. The relation between the growth deviations and severity of the inflammation, condylar shape, the micro-architecture, and the quality of the bone has not previously been investigated. This paper studies the effect on the bony structures in mandibular condylar development in rabbits with antigen-induced arthritis. METHODS: Included were 42 juvenile rabbits with ovalbumin-induced arthritis of the TMJs treated with intraarticular saline, intraarticular etanercept or subcutaneous etanercept. A TMJ from each animal was scanned using micro-computed tomography and structural parameters were calculated. Three-dimensional reconstructions of the mandibular condyle were scored blindly as normal or abnormal. TMJs were stratified for condylar morphology and were evaluated against data on trabecular structural parameters, inflammation, degree of mineralization, overall mandibular growth, and mineral apposition rate. RESULTS: Abnormal morphology were seen in 15/32 animals available for data analysis. Erosions were an uncommon finding. Abnormal morphology was strongly related to the degree of inflammation. The trabecular separation was larger in group with abnormal morphology than in the group with normal morphology. Abnormal condylar morphology was not associated with overall mandibular growth. No differences were observed in mineral apposition rate. No differences in structural parameters were seen according to treatment modality. CONCLUSION: We showed that severe inflammation in the TMJs during mandibular development was associated with morphological changes in the mandibular condyle. These changes were predominantly seen at the macro-morphological level and only very few differences were structural.

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.

The influence of hemostatic agents on bone healing after sternotomy in a porcine model.

BACKGROUND: Sternotomy is the preferred access to the mediastinum. During sternotomy, trabecular bone is exposed, often resulting in bleeding, which can be treated with mechanical hemostatic agents; however, their influence on the healing process is relatively unexplored. The aim of this study was to investigate the influence of two hemostatic agents: bone wax (BW) and a water-soluble polymer wax, Ostene (WSW), on the mechanical and histologic characteristics of healing sternal bone. METHODS: Twenty-four pigs underwent sternotomy and were randomized into three groups: WSW, BW, or no hemostatic treatment (control). Bone samples were obtained 6 weeks postoperatively. RESULTS: Fracture strength (Fmax) and maximum stiffness (dF/dx) was lower in the BW group than in controls (Fmax: 175.2 vs. 255.8 N, dF/dx: 165.2 vs. 375.4 N/mm,) (p < 0.05). The stiffness did not differ statistically between the WSW and BW groups (298.4 vs 165.2 N/mm) nor did the fracture strength (211.4 vs 175.2 N). The fraction of granulomatous tissue was higher in the BW group compared with both the WSW group (79.1 vs. 16.52%) (p < 0.001) and controls (79.1 vs. 11.2%) (p < 0.001). There was more calcified tissue in controls than in the BW group (23.4 vs. 10.8%) (p < 0.05). CONCLUSIONS: In a porcine model, BW significantly inhibited sternal healing and was associated with chronic inflammation and reduced mechanical integrity. The WSW did not, to the same degree as BW, inhibit bone healing and thus presents an alternative treatment option for sternal bleeding.

The effect of haemostatic devices on bone healing 6 months postoperatively in sternotomized pigs.

OBJECTIVES: Bone wax is frequently used to diminish bleeding after sternotomy. Water-soluble polymer wax has been shown to diminish postoperative bleeding and, unlike traditional bone wax, to be absorbed and removed by the organism in an unchanged state. We have previously shown that bone wax impairs early bone healing after sternotomy, whereas polymer wax does not. This difference was observed 6 weeks postoperatively and questions arose as to whether these effects were long term. Therefore, we hypothesized that bone wax impairs bone healing in sternotomized pigs 6 months postoperatively, whereas polymer wax does not. METHODS: Fourteen Landrace/Yorkshire pigs were sternotomized and then randomly assigned to haemostasis by either bone wax (WAX-group) or water-soluble polymer wax (POL-group). After 6 months, the pigs were euthanized and the sternum was removed and prepared for further assessment. Bone fracture strength and bone stiffness were determined using a modified three-point bending test, whereas bone healing was examined by means of quantitative histology. Six pigs died before the end of the study due to failure to thrive, valve prosthesis endocarditis and coronary artery occlusion. RESULTS: The mechanical testing showed no difference between groups with regard to fracture strength [WAX-group versus POL-group; 214.8 (85.5-478.5) vs 203.8 (90.4-478.5) N, P = 0.986] or maximum stiffness [213.0 (81.5-409.5) vs 348.5 (23.3-689.5) N/mm, P = 0.128]. Histology showed predominance of fibroblast-covered surfaces [10.6% (1.8-23.3%) vs 4.1% (0.0-13.0%), P < 0.001] and fibrous tissue volume [45.4% (6.9-82.0%) vs 17.4% (2.9-55.0%), P < 0.001] in animals treated with bone wax. The volume fraction of calcified bone tended to be higher in the POL-group [26.8% (4.3-35.8%) vs 16.7% (1.5-35.8%), P = 0.065]. Granulomas comprised 12.5% (0.0-78.9%) of the volume fraction in the WAX-group compared with 0.0% (0.0-0.0%) in the POL-group (P < 0.001). CONCLUSION: Bone wax and water-soluble polymer wax had similar long-term effects on bone mechanical properties. Histology confirmed our hypothesis and showed a more extensive foreign body reaction in animals treated with bone wax than in those treated with water-soluble polymer wax.

The effect of long-term methylprednisolone treatment on the femoral head in growing pigs.

The effect of long term steroid treatment on coagulation, intraosseous pressure (IOP), femoral head (FH) blood flow, and histology in the normal organism was investigated in this study in growing pigs. From 24 growing female Danish Landrace pigs from 12 litters, 12 animals daily received 100 mg methylprednisolone orally for three months. Their 12 sister pigs served as controls without steroid treatment. Prothrombin time, activated partial thromboplastin time (aPTT), fibrinogen, and antithrombin III levels were recorded in jugular venous blood. Blood flow of the hip regions was measured by means of the radioactive microsphere technique. Metaphyseal and epiphyseal IOP of the left or right proximal femur were measured. Histomorphometry of the left or right FH epiphysis was performed. Major growth inhibition was found in the corticosteroid (CS) treated group. In CS pigs, aPTT was shortened to 50% compared to control pigs. Plasma fibrinogen was higher in the CS animals. Total FH blood flow was not different while regional blood flow in the cranial subregion of the FH epiphysis was higher in the CS group. Metaphyseal and epiphyseal IOP of the proximal femur were not different in the CS animals. Histomorphometrically, cancellous bone volume (23 +/- 1% vs. 34 +/- 2%; p < 0.001) and bone turnover (10 +/- 2% vs. 55 +/- 8%; p < 0.001) of the FH epiphysis was lowerin the CS than in the control group. The FH epiphysis of the CS animals invariably showed an irregular cartilage-bone interface with cartilaginous projections into the subchondral bone mainly in its cranial part. In normal growing pigs, long term high dose CS treatment has induced a hypercoagulable state of plasma via the intrinsic pathway of coagulation, cartilaginous projections into FH subchondral bone, FH osteopenia, and reduced bone turnover. Long-term steroid treatment did not produce FH necrosis or FH IOP alterations in the immature pig model.

Gentamicin-enriched, water-soluble polymer wax reduces the burden of infection after sternotomy in pigs.

OBJECTIVES: One of the most frequent complications in cardiac surgery is postoperative bleeding from the sternum. To diminish the risk of bleeding, bone wax is frequently used for haemostasis. However, we have previously shown that bone wax impairs bone healing and induces inflammation in the sternum. A new, water-soluble polymer wax enriched with gentamicin has haemostatic properties similar to bone wax and may diminish the risk of infection. The purpose of this study was to determine whether the gentamicin-enriched, water-soluble polymer wax could reduce infection rates when compared with bone wax in a porcine model. METHODS: Thirty-two Landrace/Yorkshire pigs were sternotomized and randomized to haemostasis by gentamicin-enriched, water-soluble polymer wax (Gen group) or bone wax (Wax group). After 4 weeks the pigs were euthanized. Blood samples were analysed for the fraction and concentration of neutrophil granulocytes and C-reactive protein and the surgical site was biopsied. Stereology was performed on histological samples, and the magnitude of infection was quantified as the areas of microabscesses, granulomas and tissue with acute inflammation compared with the total tissue area. RESULTS: The temperature was 38.2 °C in the Gen group vs 38.6 °C in the Wax group, P < 0.05. No animals in the Gen group and three in the Wax group showed a temperature >39.3 °C. Neutrophil granulocyte concentration was 5.00 × 10(9)/l in the Gen group and 6.92 × 10(9)/l in the Wax group, P = 0.277, with a leucocyte fraction of 20.9% vs 29.3%, P = 0.119. C-reactive protein (CRP) was 142 mg/l in the Gen group compared with 318 mg/l in the Wax group, P = 0.106. Histological samples showed acute inflammatory changes in 5.0% of the tissue in the Gen group vs 18.3% in the Wax group, P < 0.001. Microabscesses were present in 0.3% of the sample tissue in the Gen group vs 2.2% in the Wax group, P < 0.001. Concentrations of gentamicin were >100 mg/l in mediastinal fluid and <2 mg/l in venous blood. CONCLUSIONS: When used for haemostasis after sternotomy in a porcine model, gentamicin-enriched, water-soluble polymer wax reduces sign of infection when compared with bone wax and therefore appears to be a more suitable choice for preventing postoperative, sternal osteomyelitis.

Differing effects of PTH 1-34, PTH 1-84, and zoledronic acid on bone microarchitecture and estimated strength in postmenopausal women with osteoporosis: an 18-month open-labeled observational study using HR-pQCT.

Whereas the beneficial effects of intermittent treatment with parathyroid hormone (PTH) (intact PTH 1-84 or fragment PTH 1-34, teriparatide) on vertebral strength is well documented, treatment may not be equally effective in the peripheral skeleton. We used high-resolution peripheral quantitative computed tomography (HR-pQCT) to detail effects on compartmental geometry, density, and microarchitecture as well as finite element (FE) estimated integral strength at the distal radius and tibia in postmenopausal osteoporotic women treated with PTH 1-34 (20 µg sc daily, n = 18) or PTH 1-84 (100 µg sc daily, n = 20) for 18 months in an open-label, nonrandomized study. A group of postmenopausal osteoporotic women receiving zoledronic acid (5 mg infusion once yearly, n = 33) was also included. Anabolic therapy increased cortical porosity in radius (PTH 1-34 32 ± 37%, PTH 1-84 39 ± 32%, both p < 0.001) and tibia (PTH 1-34 13 ± 27%, PTH 1-84 15 ± 22%, both p < 0.001) with corresponding declines in cortical density. With PTH 1-34, increases in cortical thickness in radius (2.0 ± 3.8%, p < 0.05) and tibia (3.8 ± 10.4%, p < 0.01) were found. Trabecular number increased in tibia with both PTH 1-34 (4.2 ± 7.1%, p < 0.05) and PTH 1-84 (5.3 ± 8.3%, p < 0.01). Zoledronic acid did not impact cortical porosity at either site but increased cortical thickness (3.0 ± 3.5%, p < 0.01), total (2.7 ± 2.5%, p < 0.001) and cortical density (1.5 ± 2.0%, p < 0.01) in tibia as well as trabecular volume fraction in radius (2.5 ± 5.1%, p < 0.05) and tibia (2.2 ± 2.2%, p < 0.01). FE estimated bone strength was preserved, but not increased, with PTH 1-34 and zoledronic acid at both sites, whereas it decreased with PTH 1-84 in radius (-2.8 ± 5.8%, p < 0.05) and tibia (-3.9 ± 4.8%, p < 0.001). Conclusively, divergent treatment-specific effects in cortical and trabecular bone were observed with anabolic and zoledronic acid therapy. The finding of decreased estimated strength with PTH 1-84 treatment was surprising and warrants confirmation.

Parathyroidectomy improves bone geometry and microarchitecture in female patients with primary hyperparathyroidism: a one-year prospective controlled study using high-resolution peripheral quantitative computed tomography.

Following parathyroidectomy (PTX), bone mineral density (BMD) increases in patients with primary hyperparathyroidism (PHPT), yet information is scarce concerning changes in bone structure and strength following normalization of parathyroid hormone levels postsurgery. In this 1-year prospective controlled study, high-resolution peripheral quantitative computed tomography (HR-pQCT) was used to evaluate changes in bone geometry, volumetric BMD (vBMD), microarchitecture, and estimated strength in female patients with PHPT before and 1 year after PTX, compared to healthy controls. Twenty-seven women successfully treated with PTX (median age 62 years; range, 44-75 years) and 31 controls (median age 63 years; range, 40-76 years) recruited by random sampling from the general population were studied using HR-pQCT of the distal radius and tibia as well as with dual-energy X-ray absorptiometry (DXA) of the forearm, spine, and hip. The two groups were comparable with respect to age, height, weight, and menopausal status. In both radius and tibia, cortical (Ct.) vBMD and Ct. thickness increased or were maintained in patients and decreased in controls (p < 0.01). Radius cancellous bone architecture was improved in patients through increased trabecular number and decreased trabecular spacing compared with changes in controls (p < 0.05). No significant cancellous bone changes were observed in tibia. Estimated bone failure load by finite element modeling increased in patients in radius but declined in controls (p < 0.001). Similar, albeit borderline significant changes in estimated failure load were found in tibia (p = 0.06). This study showed that females with PHPT had improvements in cortical bone geometry and increases in cortical and trabecular vBMD in both radius and tibia along with improvements in cancellous bone architecture and estimated strength in radius 1 year after PTX, reversing or attenuating age-related changes observed in controls.

Effects on bone geometry, density, and microarchitecture in the distal radius but not the tibia in women with primary hyperparathyroidism: A case-control study using HR-pQCT.

Patients with primary hyperparathyroidism (PHPT) have continuously elevated parathyroid hormone (PTH) and consequently increased bone turnover with negative effects on cortical (Ct) bone with preservation of trabecular (Tb) bone. High-resolution peripheral quantitative computed tomography (HR-pQCT) is a new technique for in vivo assessment of geometry, volumetric density, and microarchitecture at the radius and tibia. In this study we aimed to evaluate bone status in women with PHPT compared with controls using HR-pQCT. The distal radius and tibia of 54 women--27 patients with PHPT (median age 60, range 44-75 years) and 27 randomly recruited age-matched healthy controls (median age 60, range 44-76 years)--were imaged using HR-pQCT along with areal bone mineral density (aBMD) by dual-energy X-ray absorptiomentry (DXA) of the ultradistal forearm, femoral neck, and spine (L1-L4). Groups were comparable regarding age, height, and weight. In the radius, patients had reduced Ct area (Ct.Ar) (p = .008), Ct thickness (Ct.th) (p = .01) along with reduced total (p = .002), Ct (p = .02), and Tb (p = .02) volumetric density and reduced Tb number (Tb.N) (p = .04) and increased Tb spacing (Tb.sp) (p = .05). Ct porosity did not differ. In the tibia, no differences in HR-pQCT parameters were found. Moreover, patients had lower ultradistal forearm (p = .005), spine (p = .04), and femoral neck (p = 0.04) aBMD compared with controls. In conclusion, a negative bone effect of continuously elevated PTH with alteration of HR-pQCT assessed geometry, volumetric density, and both trabecular and cortical microarchitecture in radius but not tibia was found along with reduced aBMD by DXA at all sites in female patients with PHPT. © 2010 American Society for Bone and Mineral Research.

Associations between amino acids and bone mineral density in men with idiopathic osteoporosis.

Idiopathic osteoporosis in middle-aged men is characterized by low-level bone formation. Inhibited anabolism may be involved in the pathogenesis of the disease and amino acids may be of importance. In the present study fasting amino acid profiles in plasma and erythrocytes were determined in 22 male idiopathic osteoporosis (MIO) patients and in 20 age-matched healthy men and associated with bone mineral density, bone histomorphometry and hormones. The osteoporotic patients had normal plasma essential amino acids but increased non-essential amino acids (p=0.001), particularly glutamine and glycine. The ratio essential/non-essential amino acids, an index of protein nutritional status, was decreased in the MIO patients (0.59 (0.04) µmol/l, mean (SD)), compared to controls (0.66 (0.05), p=0.001). In the MIO patients, the ratio essential/non-essential plasma amino acids (r=0.60, p=0.003) was positively correlated with lumbar spine bone mineral density. The erythrocyte amino acids represent a large proportion of the free amino acids in blood. A novel finding was the lower levels of erythrocyte tryptophan in MIO (12 (2) µmol/l) compared to controls (16 (3), p=0.001) and decreased erythrocyte/plasma ratio (0.28 (0.07) vs. 0.33, (0.06), p<0.01), suggesting an altered amino acid transport of tryptophan between plasma and erythrocytes. In the combined group of MIO and control men (n=42), bone mineral density was positively correlated with erythrocyte tryptophan in both the lumbar spine (r=0.45, p=0.003) and femoral neck (r=0.56, p<0.001). The bone histomorphometric variables wall thickness, trabecular thickness and mineral apposition rate were all positively associated with erythrocyte tryptophan levels in the MIO patients. In the combined group of MIO and controls, a multiple regression analysis showed that erythrocyte tryptophan could explain 22% of the variation of lumbar spine and 30% of the variation in femoral neck bone mineral density. We conclude that men with idiopathic osteoporosis have changes in free amino acid profiles which indicate their altered utilization. The correlations between tryptophan and bone mineral density and bone histomorphometry suggest a link between tryptophan and osteoblast function which may be important for bone health.

[Steady production of scientific papers from medical and pharmaceutical Ph.D. graduates from 1993 to 2000]. / Stabil produktion af publikationer for ph.d.-årgangene 1993-2000.

INTRODUCTION: According to international standards, Denmark's production of scientific papers is high, but is slowly losing ground. The reformed research education was intended to strengthen Denmark's position, but some fear that it will have the opposite effect. MATERIAL AND METHODS: Based on the Registry of Ph.D. students and data from the Central Office of Civil Registration, we conducted a survey among 1170 persons previously enrolled in a Ph.D. program. Data on published papers were stratified according to gender, age, master degree, institution, year and length of enrolment. The response rate was 46%. RESULTS: A total of 6-7 papers, including 3 first authorships, were published during the Ph.D. study and the first three years thereafter. Only about 10% did not publish in these periods. Over a 10-year time span, the number of publications before, during and three years after the Ph.D. degree was stable. Women and men published the same number of papers based on the Ph.D. project; however the total number of research publications was higher for men. CONCLUSION: As measured by the number of publications, the Danish Ph.D. education is solid and independent of gender, age, and time. However, in order to strengthen the overall Danish biomedical research production additional public funding and time allocated to clinical research is necessary.

[Key issues for the number of publications by Ph.D. graduates in medicine and pharmaceutical sciences]. / Faktorer af betydning for antallet af publikationer fra ph.d.-graduerede i perioden 1993-2000.

INTRODUCTION: Scientific production by Ph.D. students is a matter of ongoing debate. The key issues for the number of publications during and after the Ph.D. study are not sufficiently described. MATERIAL AND METHODS: Based on the Registry of Ph.D. students and data from the Central Office of Civil Registration, we conducted a survey among 1170 persons previously enrolled in a Ph.D. programme in medicine or pharmaceutical sciences. Data on activities such as supervision and teaching, social issues and economy in the research team were stratified according to sex, age, master degree, institution, year and length of enrolment. The data were modelled in multiple linear regression using the number of peer-reviewed publications as the outcome. The response rate was 60%. RESULTS: The number of publications based on the Ph.D. project was only marginally influenced by the investigated variables. A high total number of publications was associated with men, with having been a Ph.D. supervisor, with research groups described as having a good atmosphere and sufficient financial funding. CONCLUSION: The medical and pharmaceutical Ph.D. programmes display an inherent strength concerning the process. Although our study supplies confirmatory data, it also shows that the team spirit is important to scientific productivity.