A high low-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio as a potential risk factor for corticosteroid-induced osteonecrosis in rabbits

Effects of Thymoquinone on Urotensin-II and TGF-β1 Levels in Model of Osteonecrosis in Rats

Objectives: We aimed to investigate the therapeutic effects of thymoquinone (TMQ) treatment in osteonecrotic rats by evaluating protein levels, osteonecrosis (ON) levels, fatty acid degeneration, oxidative status, and plasma levels of Urotensin-II (U-II) and transforming growth factor-beta (TGF-β1). Materials and Methods: 40 weight-matched adult male Wistar rats were grouped as control (n = 10), methylprednisolone acetate (MPA) (n = 10), thymoquinone (TMQ) (n = 10), and MPA + TMQ (n = 10). To induce ON, 15-week-old animals were subcutaneously injected with MPA at a dose of 15 mg/kg twice weekly for 2 weeks. TMQ was injected into 15-week-old rats via gastric gavage at a dose of 80 mg/kg per day for 4 weeks. The rats in the MPA + TMQ group were administered TMQ 2 weeks before the MPA injection. At the end of the treatments, cardiac blood samples and femur samples were collected for biochemical and histological evaluations. Results: In the control and TMQ groups, no ON pattern was observed. However, in tissues exposed to MPA, TMQ treatment resulted in significantly decreased ON levels compared to the MPA group. The number of cells that were positive for 8-OHdG and 4-HNE was significantly lower in the MPA + TMQ group than in the MPA group (p < 0.05). In terms of TGF-β1 and U-II levels, we observed that both TGF-β1 (367.40 ± 23.01 pg/mL vs. 248.9 ± 20.12 pg/mL) and U-II protein levels (259.5 ± 6.0 ng/mL vs. 168.20 ± 7.90 ng/mL) increased significantly in the MPA group compared to the control group (p < 0.001). Furthermore, TGF-β1 (293.50 ± 14.18 pg/mL) and U-II (174.80 ± 4.2 ng/mL) protein levels were significantly decreased in the MPA + TMQ group compared to the MPA group (p < 0.05 and p < 0.01, respectively). There was a statistically positive correlation (p < 0.05) between the TGF-β1 and U-II protein levels in all groups (p = 0.002, rcontrol = 0.890; p = 0.02, rTMQ = 0.861; p = 0.024, rMPA+TMQ = 0.868) except for the MPA group (p < 0.03, rMedrol = -0.870). Conclusions: As far as we know, this is the first study to demonstrate the curative functions of TMQ on ON by causing a correlated decrease in the expression of U-II and TGF-β1 in the femoral heads of rats.

Relationship of idiopathic femoral head necrosis with blood lipid metabolism and coagulation function: A propensity score-based analysis

Background

Nontraumatic osteonecrosis of the femoral head (ONFH) can be corticosteroid-induced, alcohol-induced, and idiopathic ONFH (IONFH). Although corticosteroid- and alcohol-induced ONFH has been investigated extensively regarding its relationship with blood lipids and coagulation factor levels. However, the effect of blood lipid metabolism and coagulation function on IONFH has rarely been studied. Therefore, this study aimed to analyse the relationship of IONFH with blood lipid and coagulation indicators.

Methods

Total 680 patients diagnosed with IONFH in our institution during January 2011-June 2019 who met the inclusion criteria composed the case group; 613 healthy persons who underwent physical examination at our institution during the same period composed the control group. Propensity scores were used for baseline feature matching, and two matching groups each with 450 patients were established. After the matching, blood lipid and coagulation factor levels of both groups were comparatively analysed.

Results

The case group showed significantly higher total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL) levels, low-density/high-density lipoprotein (LDL/HDL) ratio, and apolipoprotein B (Apo-B) levels than the control group (p < 0.05). Conversely, the HDL and apolipoprotein A (Apo-AI) levels in the case group were significantly lower than those in the control group (p < 0.05). Regarding coagulation indicators, the activated partial thromboplastin time and prothrombin time were lower in the case group than in the control group; however, the differences were insignificant (p > 0.05). Furthermore, fibrinogen (FIB) levels and thrombin time (TT) in the case group were higher than those in the control group. There were significant differences between the two groups only in terms of FIB levels (p < 0.05), while TT was not significantly different (p > 0.05).

Conclusions

IONFH has strong associations with blood lipid metabolism and coagulation function, which provide an avenue for exploring the mechanism of IONFH.

Abnormal Lipid Profiles in Nontraumatic Osteonecrosis of the Femoral Head: A Comparison with Osteoarthritis Using Propensity Score Matching

BACKGROUND

Abnormal lipid metabolism may play an important role in the development of nontraumatic osteonecrosis of the femoral head (ON). By comparing lipid biomarkers in patients with ON and osteoarthritis (OA) after propensity score matching, we sought to reveal (1) common lipid biomarkers that are abnormal in ON regardless of the etiology and (2) specific lipid biomarkers associated with ON according to the etiology.

METHODS

Among 2,268 patients who underwent primary THA, 1,021 patients were eligible for this study. According to the Association Research Circulation Osseous criteria, ON was classified as either idiopathic (n = 230), alcohol-associated (n = 293), or glucocorticoid-associated ON (n = 132). Most common cause of OA was hip dysplasia in 106 patients (47%). We investigated patient lipid profiles by assessing total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides (TGs), apolipoprotein (Apo) A1 and B, lipoprotein (a) levels and ApoB/A1 ratio. Since age and body mass index affect the lipid profile, we performed propensity score matching to select 304 patients for final analysis and compared lipid profiles between the ON and OA groups. We also compared biomarkers between the ON subgroups and the OA group.

RESULTS

Overall, the ON group showed lower HDL-C (p < 0.001), higher TGs (p = 0.001) levels and higher ApoB/A1 ratio (p = 0.003). Idiopathic ON patients demonstrated lower HDL-C (p = 0.032), higher TGs (p = 0.016), ApoB (p = 0.024) levels and ApoB/A1 ratio (p = 0.008). The alcohol-associated ON subgroup showed lower HDL-C (p < 0.001), higher TGs (p = 0.010) levels and ApoB/A1 ratio (p = 0.030). Finally, the steroid-associated ON subgroup demonstrated lower HDL-C (p = 0.003), higher TGs (p = 0.039), lower TC (p = 0.022), LDL-C (p = 0.021), and ApoA1 (p = 0.004) levels.

CONCLUSIONS

Higher TGs and lower HDL-C levels were associated with nontraumatic ON regardless of the etiology. Additionally, idiopathic ON was associated with higher ApoB levels and ApoB/A1 ratio. Alcohol-associated ON was related to higher ApoB/A1 ratio, and steroid-associated ON paired with decreased TC, LDL-C, and ApoA1 levels. Our findings may support future efforts for prevention and management of nontraumatic ON.

LEVEL OF EVIDENCE

Diagnostic Level III.

The efficacy of core decompression for steroid-associated osteonecrosis of the femoral head in rabbits

Although core decompression (CD) is often performed in the early stage of osteonecrosis of the femoral head (ONFH), the procedure does not always prevent subsequent deterioration and the effects of CD are not fully clarified. The aim of this study is to evaluate the efficacy of CD for steroid-associated ONFH in rabbits. Twelve male and 12 female New Zealand rabbits were injected intramuscularly 20 mg/kg of methylprednisolone once and were divided into the disease control and CD groups. In the disease control group, rabbits had no treatment and were euthanized at 12 weeks postinjection. In the CD group, rabbits underwent left femoral CD at 4 weeks postinjection and were euthanized 8 weeks postoperatively. The left femurs were collected to perform morphological, biomechanical, and histological analysis. Bone mineral density and bone volume fraction in the femoral head in the CD group were significantly higher than in the disease control group. However, no difference in the mechanical strength was observed between the two groups. Histological analysis showed that alkaline phosphatase and CD31 positive cells significantly increased in the males after CD treatment. The number of empty lacunae in the surrounding trabecular bone was significantly higher in the CD group. The current study indicated that CD improved the morphological properties, but did not improve the mechanical strength in the femoral head at early-stage ONFH. These data suggest the need for additional biological, mechanical strategies, and therapeutic windows to improve the outcome of early-stage steroid-associated ONFH.

The relationship between apolipoprotein genes polymorphisms and susceptibility to osteonecrosis of the femoral head: a meta-analysis

Background

The objective of this study was to evaluate whether apolipoprotein gene polymorphisms confer susceptibility to osteonecrosis of the femoral head (ONFH).

Methods

The relevant literature was screened from databases of Pubmed, Embase, Wanfang, Weipu and China National Knowledge Internet (CNKI) until May, 2017. In addition, odds ratio (OR) and its corresponding 95% confidence interval (CI) were used as a measure of effect size for calculating effect size.

Results

Totally, six case-control studies were included in this meta-analysis. It revealed that ApoB-C7623T polymorphism frequency was increased in ONFH group than in control group under three genetic models, including allele model (T vs. C, OR = 4.5149, 95% CI: 1.6968–12.0134); additive model (TC vs. CC, OR = 6.2515, 95% CI: 2.0939–18.6640); and dominant model (TT + TC vs. CC, OR = 5.4998, 95% CI: 1.9246–15.7163). In addition, the increased risk of ONFH were related to ApoA1-rs1799837 polymorphism under additive model (AA vs. GG, OR = 1.4175, 95% CI: 1.0522–1.9096) and recessive model (AA vs. GG + AG, OR = 1.7727, 95% CI: 1.3399–2.3452). However, four ApoB rs1042031, rs693, 3’-VNTR and G12619A polymorphisms under the all genetic models were not associated with susceptibility to ONFH.

Conclusion

The T allele and TC genotype of ApoB-C7623T and AA genotype of ApoA1-rs1799837 may contribute to increase the risk of ONFH.

Genetics of pleiotropic effects of dexamethasone

OBJECTIVES

Glucocorticoids such as dexamethasone have pleiotropic effects, including desired antileukemic, anti-inflammatory, or immunosuppressive effects, and undesired metabolic or toxic effects. The most serious adverse effects of dexamethasone among patients with acute lymphoblastic leukemia are osteonecrosis and thrombosis. To identify inherited genomic variation involved in these severe adverse effects, we carried out genome-wide association studies (GWAS) by analyzing 14 pleiotropic glucocorticoid phenotypes in 391 patients with acute lymphoblastic leukemia.

PATIENTS AND METHODS

We used the Projection Onto the Most Interesting Statistical Evidence integrative analysis technique to identify genetic variants associated with pleiotropic dexamethasone phenotypes, stratifying for age, sex, race, and treatment, and compared the results with conventional single-phenotype GWAS. The phenotypes were osteonecrosis, central nervous system toxicity, hyperglycemia, hypokalemia, thrombosis, dexamethasone exposure, BMI, growth trajectory, and levels of cortisol, albumin, and asparaginase antibodies, and changes in cholesterol, triglycerides, and low-density lipoproteins after dexamethasone.

RESULTS

The integrative analysis identified more pleiotropic single nucleotide polymorphism variants (P=1.46×10(-215), and these variants were more likely to be in gene-regulatory regions (P=1.22×10(-6)) than traditional single-phenotype GWAS. The integrative analysis yielded genomic variants (rs2243057 and rs6453253) in F2RL1, a receptor that functions in hemostasis, thrombosis, and inflammation, which were associated with pleiotropic effects, including osteonecrosis and thrombosis, and were in regulatory gene regions.

CONCLUSION

The integrative pleiotropic analysis identified risk variants for osteonecrosis and thrombosis not identified by single-phenotype analysis that may have importance for patients with underlying sensitivity to multiple dexamethasone adverse effects.

The impact of high total cholesterol and high low-density lipoprotein on avascular necrosis of the femoral head in low-energy femoral neck fractures

Background

Avascular necrosis of the femoral head (AVNFH) typically constitutes 5 to 15% of all complications of low-energy femoral neck fractures, and due to an increasingly ageing population and a rising prevalence of femoral neck fractures, the number of patients who develop AVNFH is increasing. However, there is no consensus regarding the relationship between blood lipid abnormalities and postoperative AVNFH. The purpose of this retrospective study was to investigate the relationship between blood lipid abnormalities and AVNFH following the femoral neck fracture operation among an elderly population.

Methods

A retrospective, comparative study was performed at our institution. Between June 2005 and November 2009, 653 elderly patients (653 hips) with low-energy femoral neck fractures underwent closed reduction and internal fixation with cancellous screws (Smith and Nephew, Memphis, Tennessee). Follow-up occurred at 1, 6, 12, 18, 24, 30, and 36 months after surgery. Logistic multi-factor regression analysis was used to assess the risk factors of AVNFH and to determine the effect of blood lipid levels on AVNFH development. Inclusion and exclusion criteria were predetermined to focus on isolated freshly closed femoral neck fractures in the elderly population. The primary outcome was the blood lipid levels. The secondary outcome was the logistic multi-factor regression analysis.

Results

A total of 325 elderly patients with low-energy femoral neck fractures (AVNFH, n = 160; control, n = 165) were assessed. In the AVNFH group, the average TC, TG, LDL, and Apo-B values were 7.11 ± 3.16 mmol/L, 2.15 ± 0.89 mmol/L, 4.49 ± 1.38 mmol/L, and 79.69 ± 17.29 mg/dL, respectively; all of which were significantly higher than the values in the control group. Logistic multi-factor regression analysis showed that both TC and LDL were the independent factors influencing the postoperative AVNFH within femoral neck fractures.

Conclusions

This evidence indicates that AVNFH was significantly associated with blood lipid abnormalities in elderly patients with low-energy femoral neck fractures. The findings of this pilot trial justify a larger study to determine whether the result is more generally applicable to a broader population.

Femoral perfusion after pulsed electromagnetic field stimulation in a steroid-induced osteonecrosis model

This study was designed to evaluate femoral perfusion after pulsed electromagnetic field (PEMF) stimulation in a steroid-induced osteonecrosis rabbit model by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Steroid-induced osteonecrosis was produced by single intramuscular injection of methylprednisolone in 15 rabbits. Eight rabbits underwent PEMF stimulation (PEMF group) and seven did not (control group). DCE-MRI was performed before PEMF stimulation, immediately before steroid administration, and 1, 5, 10, and 14 days after steroid administration. Regions of interest were set in the bilateral proximal femora. Enhancement ratio (ER), initial slope (IS), and area under the curve (AUC) were analyzed. ER, IS, and AUC in the control group significantly decreased after steroid administration compared with before administration (P<0.05). In PEMF group, IS significantly decreased; however, ER and AUC showed no significant differences after steroid administration compared with before. ER and IS in PEMF group were higher than in control group until 10th day, and AUC was higher until 5th day after steroid administration (P<0.05). PEMF stimulation restrains the decrease in blood flow after steroid administration.

Biomarkers and pharmaceutical strategies in steroid-induced osteonecrosis of the femoral head: A literature review

The underlying pathology of steroid-induced osteonecrosis of the femoral head (ONFH) is unclear but is known to be multifactorial. It is therefore difficult to find a single predictive biomarker for this disease, and multiple biomarkers are likely to contribute to ONFH progression. Investigation of protein–protein interactions is vital in order to elucidate fully the pathogenesis of this disease, and provide new treatment strategies. This review article discusses the known biomarkers and current treatment strategies for ONFH.

Cholesterol- and lanolin-rich diets may protect against steroid-induced osteonecrosis in rabbits

BACKGROUND AND PURPOSE

It remains controversial how hypercholesterolemia influences the development of steroid-induced osteonecrosis (ON). We investigated the role of hypercholesterolemia induced by a cholesterol-rich diet on the development of ON in rabbits.

METHODS

40 adult male Japanese white rabbits were randomly divided into 2 groups. 20 rabbits were maintained on a cholesterol-rich diet for 2 weeks before receiving steroid treatment (the CHOL group). The other 20 rabbits were maintained on a standard diet (the control (CTR) group). 2 weeks after the start of the study, all 40 rabbits were injected with methylprednisolone acetate (MPSL) into the right gluteus medius muscle (20 mg/kg body weight). 2 weeks after the steroid injection, both the femora and humeri were examined histopathologically for the presence of ON. Hematological analysis of the serum lipid levels was performed every week. Based on the same protocol, we also investigated the effects of lanolin, a primary component of a cholesterol-rich diet, in another group (the LA group).

RESULTS

The incidence of ON in the CHOL group (3/20) was lower than that observed in the CTR group (15/20) (p < 0.001). During the whole experiment, the levels of total cholesterol and the ratio of low-density lipoprotein to high-density lipoprotein in the CHOL group were higher than those observed in the CTR group (p < 0.001). The LA group also had a lower incidence of ON (2/20), and the lipid levels in the LA group showed similar changes to those observed in the CHOL group.

INTERPRETATION

Our findings suggest that preexisting hypercholesterolemia itself induced by a cholesterol-rich diet does not increase the risk of developing steroid-induced ON, but rather seems to diminish it. Lanolin may be the active anti-ON component of the cholesterol diet.

Cytochrome P4503A activity affects the gender difference in the development of steroid-induced osteonecrosis in rabbits

The aim of this study was to investigate cytochrome P4503A activity and its correlation with the development of osternecrosis (ON) among male and female steroid-treated rabbits. Forty adult rabbits (male, n = 20; female, n = 20) were injected once with 20 mg/kg of methylprednisolone intramuscularly. Haematologically, cytochrome P4503A activity was measured by plasma 1'-hydroxymidazolam-to-midazolam (1'-OH-MDZ/MDZ) ratio just before and 48 h after the steroid injection. We also measured the levels of oestradiol every week. Both femora and humeri were histopathologically examined for the presence of ON. Fifteen of 20 male rabbits (75%) developed ON, while 6 of 20 female rabbits (30%) did so. There was a significant difference in the rate of incidence of ON between male and female rabbits (P = 0.010). The 1'-OH-MDZ/MDZ ratio in female rabbits just before, as well as 48 h after the steroid injection was significantly higher than that in male rabbits (P = 0.039 and P = 0.001 respectively). In addition, 1'-OH-MDZ/MDZ ratio in female rabbits significantly increased in 48 h after the steroid injection (P = 0.044), while that in male rabbits did not so (P = 0.978). The levels of oestradiol in female rabbits were significantly higher than those in male rabbits during the experimental period (P = 0.008). In conclusion, this study indicates that the gender difference in cytochrome P4503A activity may be one of the important factors for the development of steroid-induced ON, possibly due to the effects of oestradiol.

Preventive effects of the anti-vasospasm agent via the regulation of the Rho-kinase pathway on the development of steroid-induced osteonecrosis in rabbits

A number of studies have suggested that ischemia is the principal pathomechanism of osteonecrosis, however, the detailed mechanism responsible for ischemia remains unclear. We examined the effects of fasudil, an anti-vasospasm agent, on the development of steroid-induced osteonecrosis in rabbits. One group of rabbits received 15mg/kg of fasudil intravenously, which were then injected once intramuscularly with 20mg/kg of methylprednisolone (n=33), and one received methylprednisolone alone as a control (n=28). Eight rabbits from each group were sacrificed 24h after methylprednisolone injection to analyze them by the expression of endothelinA-receptor and eNOS. Two weeks after the steroid injection, the femora and humeri were examined histopathologically for the incidence of osteonecrosis. In addition, plasma from each of four osteonecrosis-positive or -negative rabbits was used for the proteomic analysis in the fasudil group. The incidence of osteonecrosis was significantly lower in the fasudil group (32%) than that in the control group (75%) (P<0.01). Immunohistochemically, endothelinA-receptor expressions levels were decreased in the smooth muscle of the bone marrow in the fasudil group in comparison to that in the control group. The eNOS expressions levels in both serum and bone marrow in the MF group were significantly higher than those in the M group (P<0.05). Based on the proteomic analysis, several proteins related to vasospasm, such as fibrinogen, thrombin, and apolipoprotein E, were identified in rabbits with osteonecrosis soon after steroid administration. This study indicates that vasospasm is one of the important factors involved in the pathogenesis of steroid-induced osteonecrosis and that the anti-vasospasm agents seem to decrease the incidence of steroid-induced osteonecrosis.

Lipid metabolism abnormalities in alcohol-treated rabbits: a morphometric and haematologic study comparing high and low alcohol doses

The pathogenesis of alcohol-induced osteonecrosis remains unclear. The purpose of the present study was to evaluate the morphological changes in bone marrow fat cells and the changes in the serum lipid levels in alcohol-treated rabbits. Fifteen rabbits were randomly assigned into three groups: Four rabbits intragastrically received low-dose alcohol (LDA) (15 ml/kg per day) containing 15% ethanol for 4 weeks, five rabbits received high-dose alcohol (HDA) (30 ml/kg per day) for 4 weeks and six rabbits received physiologic saline for 4 weeks as a control group. Six weeks after the initial alcohol administration, all rabbits were sacrificed. The mean size of the bone marrow fat cells in rabbits treated with HDA was significantly larger than that in the control group (P = 0.0001). Haematologically, the levels of triglycerides and free fatty acids in the rabbits treated with both low-dose and HDA were significantly higher than those in the control group (P = 0.001 for both comparisons). The results of this study are that there are lipid metabolism abnormalities, both morphologically and haematologically, after alcohol administration. Also these findings were more apparent in rabbits treated with HDA than those treated with LDA.

Low Plasma Adiponectin as a Potential Biomarker for Osteonecrosis of the Femoral Head

Objective.

To examine whether plasma adiponectin level is correlated with osteonecrosis of the femoral head (ONFH).

Methods.

Blood adiponectin level in patients with nontraumatic ONFH (n = 120) was compared with a group of healthy subjects (n = 120). Patients with hip osteoarthritis (OA; n = 30) and traumatic ONFH (n = 45) were included as controls. Potential compounding factors, such as plasma low-density lipoprotein (LDL), high-density lipoprotein (HDL), apolipoprotein A1 (apo A1), apolipoprotein B (apo B), total cholesterol (TC), triglycerides (TG), and C-reactive protein (CRP) were also examined.

Results.

Patients with nontraumatic ONFH had significantly lower plasma levels of adiponectin than the healthy controls (7.14 ± 3.53 vs 10.93 ± 3.41 μg/ml, respectively; p < 0.001). Adiponectin level was positively correlated with HDL (r = 0.282, p < 0.001) and age (r = 0.145, p = 0.01), yet negatively correlated with body mass index (r = −0.70, p < 0.001), TG (r = −0.55, p<0.001), LDL/HDL ratio (r = −0.173, p = 0.002), and CRP (r = −0.634, p < 0.001). No correlation was seen with LDL (r = −0.017, p = 0.762). A multiple logistic regression analysis revealed that adiponectin level is an independent predictor of the presence of nontraumatic ONFH (p < 0.001, OR 0.676, 95% CI 0.546 to 0.845).

Conclusion.

Low adiponectin level is significantly associated with the presence of nontraumatic ONFH. This biomarker may be useful in assessing the potential presence of nontraumatic ONFH.

Low levels of steroid-metabolizing hepatic enzyme (cytochrome P450 3A) activity may elevate responsiveness to steroids and may increase risk of steroid-induced osteonecrosis even with low glucocorticoid dose

BACKGROUND

The main purpose of this study was to examine the relationships among osteonecrosis, steroid-metabolizing hepatic enzyme (cytochrome P450 3A; CYP3A) activity, and steroid dose to determine whether it is possible to prevent osteonecrosis in animals with low hepatic CYP3A activity by reducing exogenous steroid doses.

METHODS

Japanese white rabbits (n = 103) were divided into three groups: a group with CYP3A activity induction (by intramuscular phenobarbital injection, n = 31), a group with CYP3A activity inhibition (by oral itraconazole administration, n = 30), and a control group (n = 42). Three weeks later, all rabbits received a methylprednisolone injection. Each group was divided into two subgroups by dosage of methylprednisolone (5 or 10 mg/kg body weight). Three weeks after methylprednisolone injections, the animals were killed and histological examination was performed to determine the incidences of osteonecrosis in the six subgroups.

RESULTS

Incidence in the inhibition subgroup with 5 mg/kg steroid was higher than that in the induction subgroup receiving 10 mg/kg steroid. Thus, suppression of CYP3A activity significantly increased vulnerability to steroid-induced osteonecrosis, while increased CYP3A activity reduced this vulnerability.

CONCLUSIONS

These findings suggest that low CYP3A activity may be vulnerable to the effect of steroids and increase risk of osteonecrosis, even with a low dose of steroid.

Investigation of occurrence of osteonecrosis of the femoral head after increasing corticosteroids in patients with recurring systemic lupus erythematosus

Osteonecrosis (ON) of the femoral head is known to occur commonly in cases with systemic lupus erythematosus (SLE) that received corticosteroid (CS) treatment. However, there have been no detailed reports about the onset of ON in cases with recurrence of SLE. Using MRI, we followed up 17 patients who experienced recurrence of SLE for at least 1 year at our hospital and in whom the CS dose was increased from a maintenance dose to middle to high dose to see if ON would occur. We then compared the group that developed ON and the group that did not with respect to patient characteristics, blood test results, changes in serum lipid levels, and CS dose. ON occurred in five subjects (29.4%), revealing that osteonecrosis occurs not only when CS are first administered but also in cases which the CS dose is increased for recurrence of SLE. Especially, serum cholesterol levels and its rate of increase soared rapidly soon after increasing the CS dose in the ON group as compared with the non-ON group (P < 0.05). This suggests that increased serum lipid levels might be a contributing factor to onset of ON. Moreover, SLE disease activity index 2000 (SLEDAI-2K) scores when the CS dose was increased were significantly (P < 0.05) higher in the ON group, suggesting that SLE disease activity itself is a risk factor for onset of ON.

Effects of topiramate on weight and metabolism in children with epilepsy

AIM

To explore the mechanism of topiramate-induced weight loss in epilepsy children by monitoring metabolism indices.

METHODS

Children with epilepsy were treated with topiramate at their first clinical visit. Metabolism indices including body mass index (BMI) and its SD scores, leptin, adiponectin, leptin/adiponectin (L/A), lipid profile-insulin and Homeostasis Model Assessments (HOMA) index were collected before and after treatment.

RESULTS

Topiramate treatment significantly reduced L/A (t = 2.156, p = 0.031), and markedly increased the serum level of adiponectin (t = 3.124, p = 0.002). Moreover, there were no relationships between the metabolism indices and dosages of topiramate (p > 0.05).

CONCLUSION

Our studies find that topiramate treatment in epilepsy children increases energy metabolism, resulting in weight loss. It has been demonstrated that adiponectin play a significant role in metabolic regulations.

A novel semisynthesized small molecule icaritin reduces incidence of steroid-associated osteonecrosis with inhibition of both thrombosis and lipid-deposition in a dose-dependent manner

BACKGROUND

Intravascular-thrombosis and extravascular-lipid-deposition are the two key pathogenic events considered to interrupt intraosseous blood supply during steroid-associated osteonecrosis (ON) development. However, there are no reported candidate agents capable of simultaneously targeting these two key pathogenic events. The authors' published experimental studies have shown that Epimedium-derived flavonoids possess an anti-ON effect. Further, the authors have recently identified a small molecule Icaritin as an intestinal metabolite of Epimedium-derived flavonoids.

OBJECTIVE

The present study was to evaluate the prevention effect of the available semisynthesized small molecule Icaritin on steroid-associated ON development in a rabbit model.

METHODS

After receiving an established inductive protocol for inducing steroid-associated ON, eighty-four male 28-week-old New-Zealand white rabbits were divided into the following three daily oral administration groups, including low dose Icaritin group (L-ICT; n=28; 5 mg x kg(-1) x day(-1)), high dose Icaritin group (H-ICT; n=28; 10 mg x kg(-1) x day(-1)), and control vehicle group (CON; n=28). Before and after induction, dynamic contrast-enhanced MRI was performed on proximal femur for intra-osseous perfusion function index. Meanwhile, blood samples were examined for coagulation, fibrinolysis, lipid-transportation, endothelium injury, oxidative stress, and hepatocyte injury index, while marrow samples were quantified for adipogenic potential index of mesenchymal stem cell by in vitro culture and proliferator-activated receptor-gamma (PPARgamma) protein expression by western blot. At baseline, week 1 and 2 post-induction, 4, 8 and 16 rabbits in each group were sacrificed, respectively. After sacrifice, femora were dissected for micro-CT-based micro-angiography, followed by histological examination of ON lesion, intravascular thrombosis, extravascular fat-cell and vascular endothelial growth factor (VEGF) localized expression.

RESULTS

The ON incidence in the L-ICT and H-ICT groups was both significantly lower than that in the CON group (p<0.05 for both). The ON incidence in the H-ICT group was significantly lower than that in the L-ICT group (p<0.05). A significant decrease in the vascularization index and a significant increase in the permeability index seen in the CON group was attenuated in the L-ICT group and almost prevented in the H-ICT group at week 1 post-induction. Reduced perfusion to vessel-like structural units was more rarely found in the H-ICT group than in the L-ICT group. Regarding intravascular thrombosis, a significant increase in the thrombotic vessel count, endothelium injury index, coagulation index, and a significant decrease in both the fibrinolysis and oxidative stress index in the CON group were attenuated in the L-ICT group and prevented in the H-ICT group. For extravascular lipid-deposition, a significant increase in the fat cell area fraction, adipogenic potential index, PPARgamma expression and lipid-transportation index in the CON group was attenuated in the L-ICT group and prevented in the H-ICT group. Increased immunoreactivity of VEGF in the CON group was attenuated in the L-ICT group and prevented in the H-ICT group. Regarding safety, the hepatocyte injury index did not show significant change from baseline in any group.

CONCLUSION

Icaritin, a novel semisynthesized small molecule with osteoprotective potential, exerts dose-dependent effect on reducing incidence of steroid-associated ON with inhibition of both intravascular thrombosis and extravascular lipid-deposition. Suppression of the up-regulated PPARgamma expression for extravascular adipogenesis of mesenchymal stem cells and protection from activated oxidative stress for intravascular endothelium injury were found to be involved in the underlying mechanisms.

A mouse model for glucocorticoid-induced osteonecrosis: effect of a steroid holiday

Glucocorticoid-induced osteonecrosis is a common and dose-limiting adverse event. The goal of this study was to establish a mouse model of glucocorticoid-induced osteonecrosis suitable for testing the effects of different treatment strategies on its frequency. Fourteen murine strains were screened using various glucocorticoids, routes of administration, and diets. Four-week-old male BALB/cJ mice were treated with oral dexamethasone for up to 12 weeks either by continuous dosing or by discontinuous dosing, with or without asparaginase. Histopathological features of the distal femurs were examined by light microscopy. Osteonecrotic lesions were characterized by empty lacunae and osteocyte ghosts in trabecular bone surrounded by necrotic marrow and edema. The incidence of dexamethasone induced osteonecrosis in BALB/cJ mice was 40-45% (4/10 or 5/11) at 12 weeks. The frequency of osteonecrosis trended lower after discontinuous compared to continuous dosing for 12 weeks (8 vs. 45%) (p = 0.06) despite comparable cumulative plasma exposure. Asparaginase hastened the occurrence of osteonecrosis, which was observed as early as 4 weeks and the incidence was 50% after 6 weeks. A mouse model of glucocorticoid-induced osteonecrosis was established. Discontinuous was less osteonecrotic than continuous dexamethasone treatment, consistent with the possible benefits of a "steroid holiday" seen in clinical settings. Moreover, asparaginase hastened osteonecrosis, indicating that drugs may interact with glucocorticoids to affect osteonecrosis risk.

Relationships among magnetic resonance imaging, histological findings, and IGF-I in steroid-induced osteonecrosis of the femoral head in rabbits

OBJECTIVE

To study the relationships among magnetic resonance imaging (MRI), histological findings, and insulin-like growth factor-I (IGF-I) in steroid-induced osteonecrosis of the femoral head in rabbits.

METHODS

Thirty rabbits were randomly divided into experimental Group A (n=15) and control Group B (n=15). The 7.5 mg/kg (2 ml) of dexamethasone (DEX) and physiological saline (2 ml) were injected into the right gluteus medius muscle twice at one-week intervals in animals of Groups A and B, respectively. At 4, 8 and 16 weeks after obtaining an MRI, the rabbits were sacrificed and the femoral head from one side was removed for histological study of lacunae empty of osteocytes, subchondral vessels, and size of fat cells under microscopy, and the femoral head from the other side was removed for enzyme-linked immunoadsorbent assay (ELISA) for IGF-I.

RESULTS

At 4, 8 and 16 weeks after treatment, no necrotic lesions were detected in Group B, while they were detected in Group A. Light microscopy revealed that the fat cells of the marrow cavity were enlarged, subchondral vessels were evidently decreased, and empty bone lacunae were clearly increased. The IGF-I levels in Group A were significantly higher than those in Group B. At 8 weeks after the DEX injection, the MRI of all 20 femora showed an inhomogeneous, low signal intensity area in the femoral head, and at 16 weeks, the findings of all 10 femora showed a specific "line-like sign". The MRI findings of all femora in Group B were normal.

CONCLUSION

MRI is a highly sensitive means of diagnosing early experimental osteonecrosis of the femoral head. However, the abnormal marrow tissues appeared later than 4 weeks when the expression of IGF-I increased. This reparative factor has an early and important role in response to steroid-induced osteonecrosis of the femoral head, and provides a theoretical foundation for understanding the pathology and designing new therapies.

Comparative serum proteome expression of osteonecrosis of the femoral head in adults

Osteonecrosis of the femoral head (ONFH) is a skeletal disorder characterized by ischemic deterioration, bone marrow edema and eventually femoral head collapse. The systemic regulation of ONFH in adult patients has not been examined. Serum proteomic is an innovative tool that potentially detects simultaneous expressions of serum proteins in pathological contexts. We compared the serum proteome profiles of 11 adult patients with ONFH (3 females and 8 males) and 11 healthy volunteers (3 females and 8 males). The proteins in the aliquots of sera were subjected to isoelectric focusing, two-dimensional gel electrophoresis and silver staining. The protein spots were matched and quantified using an imaging analysis system. The differentially expressed protein spots were subjected to in-gel trypsin digestion. The peptide mass fingerprints were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/TOF) and a bioinformation search. We found that ONFH patients showed significantly higher abundances of kininogen 1 variant, complement factor C3 precursor, and complement factor H and lower levels of antithrombin III chain B, apolipoprotein A--IV precursor, and gelsolin isoform alpha precursor. These proteins of interest were reported to modulate thrombotic/fibrinolytic reactions, oxidative stress, vessel injury, tissue necrosis or cell apoptosis in several tissue types under pathological contexts. Taken together, the occurrence of ONFH was associated with various serum protein expressions. Our high--throughput serum proteomic findings indicated that multiple pathological reactions presumably occurred in ONFH.

Effect of simvastatin on steroid-induced osteonecrosis evidenced by the serum lipid level and hepatic cytochrome P4503A in a rabbit model

OBJECTIVE

This study was designed to investigate the efficacy of lipid-lowering agents in preventing steroid-induced osteonecrosis and the mechanism by which they do so in a rabbit model.

METHODS

Female Japanese white rabbits were randomly allocated to receive probucol (group P), pravastatin (group PS), simvastatin (group SS), or saline (group C) for 6 weeks (n = 15 in groups P, PS, and SS; n = 30 in group C). Methylprednisolone (20 mg/kg) was injected at 3 weeks after starting treatment, and the femurs were histologically examined bilaterally 3 weeks after methylprednisolone injection. Midazolam clearance was measured before treatment and before methylprednisolone injection to determine hepatic cytochrome P4503A (CYP3A) levels.

RESULTS

The incidence of osteonecrosis in the proximal metaphysis of the femurs in groups PS and SS was significantly lower than in group C (P < 0.05 and P < 0.0001, respectively), whereas it did not differ between groups P and C. It was significantly lower in group SS than in group PS (P < 0.05). Plasma concentrations of lipids (low-density lipoprotein, triglyceride, free fatty acid, and total cholesterol) in groups P, PS, and SS were significantly lower than in group C; and hepatic CYP3A levels were significantly higher in group SS than in groups P or PS after treatment (P < 0.005 for both).

CONCLUSIONS

Simvastatin and pravastatin significantly reduced the incidence of steroid-induced osteonecrosis in rabbits. Simvastatin was more effective in reducing the incidence of the disease, and increased CYP3A activity is a possible mechanism for this effect.

Different magnetic resonance imaging features in two types of nontraumatic rabbit osteonecrosis models

A single injection of high-dose steroid (20 mg/kg) has been reported to induce necrotic lesions in the proximal metaphysis and diaphysis of the rabbit femur. In the rabbit osteonecrosis (ON) model induced by two-dose horse serum injections, contrast-enhanced magnetic resonance imaging (MRI) and T2*-weighted dynamic MRI have been reported to detect necrotic lesions at 3 days after the second serum injection sensitively. The purpose of the present study was to determine whether contrast-enhanced MRI and T2*-weighted dynamic MRI could detect early development of necrotic lesions in the rabbit proximal femora after a single high-dose steroid injection and compare MRI features of the two types of nontraumatic rabbit ON models. We performed nonenhanced MRI, contrast-enhanced MRI and T2*-weighted dynamic MRI of bilateral proximal femora 3 days (10 femora), 1 week (10 femora), 3 weeks (10 femora), 6 weeks (18 femora) and 9 weeks (18 femora) after a single 20 mg/kg steroid injection. Femoral signal intensity of each T2*-weighted dynamic MRI was measured from a 1-cm(2) region of interest in the proximal metaphysis and diaphysis. As a control, MRI was performed in untreated animals (six femora). Histologically, no necrotic lesions were observed in the proximal femora at 3 days and 1 week. Bone marrow necrosis was observed in four (40%) femora at 3 weeks, two (11.1%) femora at 6 weeks and six (33.3%) femora at 9 weeks. Bone marrow lesion completely replaced by granulation tissue was observed in one femur at 6 weeks and one femur at 9 weeks. Histologic evidence of repair tissue surrounding bone marrow necrosis was seen after 6 weeks. Average lesion area including repair tissue was 4.40 mm(2) (range, 0.32 to 20.2 mm(2)). At 9 weeks, contrast-enhanced MRI could detect four (66.7%) femora with bone marrow necrosis of more than 4 mm(2) in the lesion area, while T2*-weighted dynamic images showed a finding of complete ischemia in only one of these four femora. In conclusion, neither contrast-enhanced MRI nor T2*-weighted dynamic MRI could detect early development of necrotic lesions in the single-dose steroid ON model. These results indicated that development of necrotic lesions in the single-dose steroid ON model was not accompanied by as diffuse a femoral hemodynamic change as the two-dose horse serum ON model.

Pitavastatin may reduce risk of steroid-induced osteonecrosis in rabbits: a preliminary histological study

Several animal and human studies suggest pharmacological approaches may prevent steroid-induced osteonecrosis (ON). We asked whether the newly developed 3-hydroxymethyl-3-glutaryl-CoA (HMG-CoA) reductase inhibitor, pitavastatin, could prevent steroid-induced ON in rabbits. We injected 65 adult male Japanese white rabbits once with 20 mg/kg of methylprednisolone acetate into the right gluteus medius muscle. The rabbits were divided into two groups; one group of 35 rabbits received pitavastatins (PS), and the other group of 30 rabbits received no prophylaxis (CTR). Hematological examinations were performed just before the steroid injection (0 weeks) and at 1 and 2 weeks after steroid injection; both the femora and the humeri were histologically examined 2 weeks postinjection. The incidence of histologic changes consistent with early ON in the PS group (13 of 35; 37%) was lower in comparison to the CTR group (21 of 30; 70%). The size of the bone marrow fat cells in the PS group (56.6 +/- 10 microm) was smaller than those in the CTR group (60 +/- 4 microm). The data suggest pitavastatin has the potential to lower the incidence of steroid-induced ON in rabbits.

Electromagnetic fields: a novel prophylaxis for steroid-induced osteonecrosis

Establishing a means to prevent osteonecrosis after corticosteroid administration is an important theme. We asked whether pulsed electromagnetic field stimulation, a noninvasive treatment, could prevent osteonecrosis. Ninety rabbits were divided into four treatment groups: (1) exposure of 10 hours per day to electromagnetic stimulation for 1 week, followed by injection of methylprednisolone (20 mg/kg), and exposure of 10 hours per day to electromagnetism for a further 4 weeks (n = 40); (2) methylprednisolone injection only (n = 40); (3) no treatment (n = 5); and (4) exposure of 10 hours per day to electromagnetism for 5 weeks (n = 5). After 5 weeks, we harvested and histologically examined femurs bilaterally. The frequency of osteonecrosis was lower in the steroid-electromagnetism group (15/40) than in the steroid-only group (26/40). No necrotic lesions were found in the two control groups. We observed no clear effects of electromagnetism on the number, location, extent, and repair of necrotic lesions and intramedullary fat cell size in affected rabbits. Pulsed electromagnetic field stimulation reportedly augments angiogenesis factors and dilates blood vessels; these effects may lower the frequency of osteonecrosis. Exposure to pulsed electromagnetic field stimulation before corticosteroid administration could be an effective means to reduce the risk of osteonecrosis.

Increased hepatic cytochrome P4503A activity decreases the risk of developing steroid-induced osteonecrosis in a rabbit model

Low hepatic cytochrome P4503A (CYP3A) activities might play an important role for inducing osteonecrosis of the femoral head (ONFH) by corticosteroids. However, the relationship between hepatic CYP3A activity and steroid-induced ONFH is unknown. We have examined the relationship between hepatic CYP3A activity and the inducibility of ONFH in a rabbit model. Sixty rabbits were divided into three groups. Hepatic CYP3A inducer (phenobarbital, group P; n = 15), inhibitor (itraconazole, group I; n = 15), or saline (group C, n = 30) was administrated for 3 weeks before intramuscular methylprednisolone. In groups P and I, hepatic CYP3A levels were measured by midazolam clearance before treatment (baseline) and before methylprednisolone injection. All animals were sacrificed 3 weeks after methylprednisolone injection and both femurs were harvested and examined histologically for osteonecrosis. Midazolam clearance was significantly increased and decreased, compared with baseline in groups P and I respectively (p < 0.0005, p < 0.002). The incidence of osteonecrosis in group P (33%) was significantly lower than in group I (100%) and group C (83%; p < 0.001 for both). The percentage necrotic area to whole bone marrow area on cross sections in group P (8.2 +/- 5.9%) was significantly lower than in group I (69.8 +/- 20.8%) and group C (51.5 +/- 30.7%; p < 0.005 for both). Hepatic CYP3A activity inversely correlated with the incidence of osteonecrosis and extent of the necrotic area caused by the same dose of corticosteroids, suggesting possible prevention of the steroid-induced osteonecrosis by reducing steroid dose in poor corticosteroid metabolizers.

ApoB C7623T polymorphism predicts risk for steroid-induced osteonecrosis of the femoral head after renal transplantation

BACKGROUND

Nontraumatic osteonecrosis of the femoral head (ONFH) is caused by disruption of blood flow. This disease often occurs in association with steroid treatment. The pathology of steroid-induced ONFH remains unclear, although abnormalities in lipid metabolism have been reported to be involved. In this study, we examined the differences of gene polymorphism frequencies of apolipoprotein B (ApoB) and apolipoprotein A1 (ApoA1), which are important proteins for lipid transport, as well as of lipid parameters, between ONFH cases and referent patients among those who were subjected to renal transplantation.

METHODS

Subjects were 158 cases who had undergone renal transplant, including 34 cases that were diagnosed as ONFH after renal transplantation and 124 cases that were not. Four single nucleotide polymorphisms including C7623T and G12619A for the ApoB gene and G75A and C83T for the ApoA1 gene were analyzed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and Taqman real-time PCR chemistry. Also, serum levels of low-density lipoprotein (LDL), high-density lipoprotein (HDL), ApoB, and ApoA1 were measured. Their relationship to ONFH was statistically evaluated.

RESULTS

A higher frequency of 7623TT or CT of the ApoB gene was observed in ONFH cases than in referent patients (P = 0.033), resulting in an elevated odds ratio that was statistically significant (adjusted odds ratio = 6.37, 95% CI = 1.53-26.5, P = 0.011). No significant relationship was observed between other genes and ONFH. Regarding lipid parameters, a higher value of ApoB/ApoA1 ratio was observed in cases (P = 0.045).

CONCLUSION

For the prediction of ONFH, it is useful to analyze ApoB C7623T and plasma ApoB/ApoA1 ratio before the administration of steroids.

Epimedium-derived phytoestrogen exert beneficial effect on preventing steroid-associated osteonecrosis in rabbits with inhibition of both thrombosis and lipid-deposition

OBJECTIVES

This study tested the effect of Epimedium-derived phytoestrogen (PE) on preventing steroid-associated osteonecrosis (ON) in rabbit model.

METHODS

Thirty 28-week-old male New-Zealand white rabbits were divided into control group (CON; n=14) and PE group (PE; n=16; 5 mg/kg body weight/day) after receiving an established inductive protocol for inducing steroid-associated ON. Before and after inductive protocol, Dynamic-MRI was employed on bilateral femora for local intra-osseous perfusion, blood samples were examined for coagulation, fibrinolysis and lipid-transportation, and marrow samples were quantified for adipogenesis-gene mRNA expression. Six weeks later, bilateral femora were dissected for Micro-CT-based micro-angiography, and then ON lesion, intravascular thrombosis and extravascular fat-cell-size were examined histopathologically.

RESULTS

The incidence of ON in the PE group (31%) was significantly lower than that in the CON group (93%). Compared to the CON group, local intra-osseous perfusion was maintained in the PE group. Blocked trunk vessels were seldom found in micro-angiography of the PE-treated rabbits. Thrombosis incidence and fat-cell-size were both significantly lower in the PE group than those in the CON group. During the early period after induction, indicator of coagulation, fibrinolysis, lipid-transportation and adipogenesis-gene expression were found with significantly changing pattern in the PE group compared to the CON group.

CONCLUSION

PE was able to exert beneficial effect on preventing steroid-associated ON in rabbits with inhibition of both thrombosis and lipid deposition.

Risk factors for dysbaric osteonecrosis

OBJECTIVES

Dysbaric osteonecrosis (DON) is a complication of ineffective decompression following exposure to high-pressure environments. This study was designed to determine risk factors for the occurrence of DON in divers.

METHODS

Fifty-six male divers received skeletal examinations by radiography to assess the occurrence of DON. A questionnaire was used to obtain clinical and diving information, including diving experience and maximum diving depth. Blood samples were collected to analyse the levels of plasminogen activator inhibitor (PAI)-1, cholesterol, triglyceride, low-density lipoprotein, very low-density lipoprotein, high-density lipoprotein, apolipoprotein A1 and apolipoprotein B.

RESULTS

Lesions of DON were detected in 31 of the 56 (55%) divers. Multivariate logistic regression analysis showed that high levels of PAI-1, a coagulation marker (odds ratio 4.281; P=0.0296) and great maximum diving depth (odds ratio 5.627; P=0.0231) were independent predictors of DON.

CONCLUSIONS

This study has shown the presence of coagulation abnormality in divers with DON. This result suggests that a pharmacological approach incorporating the use of an anticoagulant may represent a potential strategy for the prevention of DON.

Preventing organ-specific chemotherapy toxicity

Recent advances in treatment for pediatric cancers has increased overall survival rates. As more and more survive pediatric cancer, we continue to see the emergence of late effects of treatment within pediatric and the growing adult survivor population. The evaluation of late effects was initiated approximately two decades ago, and has become an extremely important facet of pediatric oncology. This review delves into several of the most serious organ-specific late effects of pediatric cancer treatment, outline what we know and what we do not currently understand about preventing or reducing them. Clinical and bench research are necessary to develop interventions that will avoid or mitigate late effects and improve the health of pediatric cancer survivors.

Low Pretransplant Bone-Mineral Density and Rapid Bone Loss Do Not Increase Risk for Avascular Osteonecrosis after Allogeneic Hematopoietic Stem Cell Transplantation

BACKGROUND

Avascular osteonecrosis (AVN) is a serious complication of allogeneic stem cell transplantation (SCT). Graft-versus-host disease and its treatment with steroids are the main risk factors; underlying diagnosis, age and gender are further risk factors. It has been speculated that low baseline bone mineral density (BMD) is associated with AVN posttransplant. Furthermore, rapid bone loss with consecutive microarchitectural changes might prone patients to AVN.

METHODS

In a single-center prospective cohort study, 255 patients undergoing allogeneic SCT for CML, AML, MDS, and ALL were followed for at least 5 years. We measured BMD (spine, femoral neck, total body) and body indices (body weight, body mass index, body composition determined by dual-energy x-ray absorptiometry) at baseline. Annual changes of BMD and body indices were prospectively observed for 5 years. Incidence of hip AVN necessitating total arthroplasty (severe adverse event) was determined. Univariate and multifactorial nominal logistic as well as Cox proportional hazard analysis were performed.

RESULTS

Severe adverse events occurred in nine patients (5-year cumulative incidence rate 6.9%). Baseline BMD and body indices were within normal limits. Rapid and intense bone loss occurred, especially during the first year, accompanied by loss of body and especially muscle mass. AVN occurrence was not associated with BMD or body indices at baseline neither with prospectively observed changes of BMD or body indices.

CONCLUSIONS

AVN is a devastating frequent complication of allogeneous SCT. Allogeneous SCT is followed by dramatic changes in BMD and body composition. However, low BMD and rapid bone loss per se do not dispose patients to AVN occurrence.

Combined effects of an anticoagulant and a lipid-lowering agent on the prevention of steroid-induced osteonecrosis in rabbits

OBJECTIVE

To investigate the effects of combination treatment with an anticoagulant (warfarin) plus a lipid-lowering agent (probucol) on the prevention of steroid-induced osteonecrosis (ON) in rabbits.

METHODS

Adult male Japanese white rabbits were injected once intramuscularly with 20 mg/kg of methylprednisolone acetate into the right gluteus medius muscle. The rabbits were then divided into 4 groups and treated as follows: one group received warfarin plus probucol (WP; n = 25), one received probucol alone (PA; n = 30), one received warfarin alone (WA; n = 26), and one received no treatment (nonprophylactic [NP]; n = 20). Two weeks after the steroid injection, the femora and humeri were examined histopathologically for the presence of ON. The sizes of the bone marrow fat cells were examined morphologically. Hematologic examinations were performed before and after the steroid injection.

RESULTS

The incidence of ON in the WP group (5%) was significantly lower than that observed in the NP group (70%). While the incidence rates of ON in the PA (38%) and WA (33%) groups were also significantly lower than that in the NP group, they were significantly higher than that observed in the WP group. The sizes of the bone marrow fat cells in both the WP (53.5 +/- 4.1 microm) and the PA (52.0 +/- 5.0 microm) groups were significantly smaller than those in the NP group (60.0 +/- 4.0 microm). We also observed a prolongation of the prothrombin time and a reduction in the plasma lipid levels in the WP group during the study.

CONCLUSION

This study experimentally confirmed that the combined use of an anticoagulant and a lipid-lowering agent helps prevent steroid-induced ON in rabbits.

Bone marrow fat cell enlargement and a rise in intraosseous pressure in steroid-treated rabbits with osteonecrosis

The etiology of steroid-induced osteonecrosis (ON) is unclear. This study was designed to determine whether bone marrow fat cell size, intraosseous pressure, and blood flow rate differed between steroid-treated rabbits with ON and those without. Twenty-nine rabbits were intramuscularly injected once with 20 mg/kg of methylprednisolone acetate (MPSL), and five rabbits were injected once with physiologic saline (PS) as a control. Intraosseous pressure and blood flow rate in the proximal femur were determined before and at 2 weeks after the injection. After these measurements, both femora and humeri were histopathologically examined for the presence of ON, and size of bone marrow fat cells were morphologically examined. At 2 weeks after steroid injection, the intraosseous pressure was significantly higher in rabbits with ON than in those without (p = 0.0251), and the blood flow rate had decreased significantly more in rabbits with ON than in those without (p = 0.0051). The size of the bone marrow fat cells was significantly (p = 0.0004) larger in rabbits with ON (diameter, 63.5 +/- 5.8 microm) than in those without (diameter, 53.3 +/- 6.9 microm). Injection of PS (5 rabbits), 1 (10 rabbits), 5 (10 rabbits), and 20 (10 rabbits) mg/kg of body weight of MPSL showed that a larger dose of steroid increased both fat cell size and prevalence of ON. These results suggest that bone marrow fat cell enlargement and a rise in intraosseous pressure may be important when considering the pathophysiology of steroid-induced ON in rabbits.