Effects of different corticosteroids on the development of osteonecrosis in rabbits.

OBJECTIVES: Osteonecrosis (ON) of the femoral head is a devastating complication occurring in patients receiving corticosteroid treatment. This study examined the effect of three corticosteroids on the development of ON in rabbits. METHODS: Thirty-nine rabbits were injected once intramuscularly with either 25 mg/kg prednisolone sodium succinate (PSL; 13 rabbits), 20 mg/kg methylprednisolone acetate (MPSL; 13 rabbits) or 20 mg/kg triamcinolone acetonide (TR; 13 rabbits). Four weeks after corticosteroid injection, the bilateral femora and humeri were examined histopathologically for the presence of ON. Haematological examinations were performed before and after corticosteroid injection. RESULTS: MPSL treatment (17/26 proximal femora, 65%) significantly increased ON incidence in the proximal femora compared with the levels seen after TR (4/26, 15%) or PSL (3/26, 12%) treatment (P < 0.01). Although not significantly increased in comparison with rabbits receiving PSL treatment (1/26 proximal humeri, 4%), ON incidence within the proximal humeri was significantly increased in MPSL-treated rabbits (6/26, 23%) in comparison with those seen in rabbits receiving TR (0/26, 0%) treatment (P < 0.05). Serum levels of cholesterol, triglyceride and free fatty acid were significantly higher 1, 2 and 4 weeks after corticosteroid treatment in rabbits treated with MPSL relative to rabbits receiving TR and rabbits with PSL treatment (P < 0.05). CONCLUSIONS: MPSL treatment significantly increased ON incidence in rabbits over levels seen after TR or PSL treatment.

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.

Osteonecrosis induced by a single administration of low-dose lipopolysaccharide in rabbits.

We succeeded in developing a novel rabbit model of nonsteroid and nontraumatic osteonecrosis (ON) by use of a single- and low-dose lipopolysaccharide (LPS) injection. This model is simple and highly reproducible for the frequent development of multifocal and widespread ON lesions. Male adult Japanese white rabbits intravenously injected with a single injection of 10 microg/kg body weight of LPS were histopathologically examined in the early phase (3 [n = 3], 5 [n = 3], and 24 h [n = 3]) and at 4 weeks (n = 22). Seventy-seven percent of the rabbits developed multifocal ON 4 weeks after LPS injection. ON was also observed in the femoral and humeral condyle. The average percentage of necrotic area/total area examined was 86.7 +/- 29.1% and 78.8 +/- 16.7% in the proximal one third of both the femoral and humeral bones, respectively. Organized thrombi in the intraosseous small-sized arteries and arterioles were frequently seen in and around the necrotic tissues. In the early phase, LPS treatment prominently induced thrombocytopenia, hyperlipidemia, and increased plasma levels of plasminogen activator inhibitor-1 (PAI-1). The plasma level of PAI-1 was significantly higher in the rabbits with ON than in those without ON (p < 0.01). The immunohistochemical expression of tissue factor was exaggerated in monocytes/macrophages and adipocytes in both the femoral and humeral bones of the LPS-treated rabbits. Histologically, marrow necrosis and fibrin thrombi could be observed at 24 h. In addition, pretreatment with an anticoagulant, warfarin potassium, significantly decreased the incidence of LPS-induced ON (33%, n = 9, p < 0.05) associated with elongation of prothrombin time. The results of our study show that a single administration of low-dose lipopolysaccharide induces multifocal and widespread ON characterized by the pathophysiological participation of hypercoagulability in ON development. Therefore, this model would be useful for elucidating the pathogenesis of nonsteroid ON in humans especially inflammatory hypercoagulability-induced as well as for developing preventive and therapeutic strategies.

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

OBJECTIVE: This study was designed to determine the potential risk factors for corticosteroid-induced osteonecrosis (ON) based on lipid metabolism, using a rabbit ON model. METHODS: Blood samples were obtained from 38 rabbits, which then received a single intramuscular injection of 20 mg/kg methylprednisolone acetate. Four weeks after the injection, the femora and humeri were examined histopathologically for the presence of ON, and the sizes of the bone marrow fat cells were also measured. RESULTS: Rabbits with and without ON differed significantly in the ratio of low-density lipoprotein cholesterol to high-density lipoprotein cholesterol (LDL/HDL cholesterol ratio), which is considered to be a serological marker of lipid transport (P=0.026). The marrow fat cells were significantly larger in the rabbits with ON than in those without ON (P<0.0001). CONCLUSION: A higher LDL/HDL cholesterol ratio was significantly associated with the development of ON, and such an elevated ratio may partly contribute to the increased size of marrow fat cells.

Prediction of the outcome of transtrochanteric rotational osteotomy for osteonecrosis of the femoral head.

We have studied the correlation between the prevention of progressive collapse and the ratio of the intact articular surface of the femoral head, after transtrochanteric rotational osteotomy for osteonecrosis. We used probit analysis on 125 hips in order to assess the ratio necessary to prevent progressive radiological collapse over a ten-year period. The results show that a minimum postoperative intact ratio of 34% was required. This critical ratio may be useful for surgical planning and in assessing the natural history of the condition.

Increased level of apolipoprotein B/apolipoprotein A1 ratio as a potential risk for osteonecrosis.

OBJECTIVE: This study was performed to investigate whether a high ratio of apolipoprotein B to apolipoprotein A1 (apo B/apo A1 ratio) is significantly associated with the risk of developing non-traumatic osteonecrosis of the femoral head (ON). METHODS: Fifty consecutive non-traumatic ON cases were compared with 50 age and sex matched controls, using both univariate and stepwise discriminant analyses, regarding the factors of corticosteroid, alcohol, cigarettes, cholesterol, triglyceride, and apo B/apo A1 ratio. To eliminate the possibility that ON or osteoarthritic change itself can increase the apo B/apo A1 ratio, a further 32 consecutive cases comprising nine traumatic ON and 23 osteoarthritis (OA) patients were analysed using Scheffe's test. RESULTS: There was a significant association between a high apo B/apo A1 ratio and the development of non-traumatic ON with both univariate (p=0.0001) and stepwise discriminant analyses (partial r(2)=0.1239, p=0.0004). The apo B/apo A1 ratio in the non-traumatic ON group was significantly higher than that in the traumatic ON (p<0.01), control (p<0.001), or the OA groups (p<0.001). CONCLUSION: A high apo B/apo A1 ratio is significantly associated with the risk of developing ON. This ratio may be useful for assessing the potential risk of developing osteonecrosis.

Effects of pulse methylprednisolone on bone and marrow tissues: corticosteroid-induced osteonecrosis in rabbits.

OBJECTIVE: To investigate the effects of pulse methylprednisolone acetate on bone and bone marrow tissues and to clarify the causal factors of corticosteroid-induced osteonecrosis (ON) by using an experimental animal model. METHODS: Male adult Japanese white rabbits were injected once with 20 mg/kg of methylprednisolone into the right gluteus medius muscle. Seven rabbits were killed at 4 weeks, 4 at 6 weeks, 4 at 8 weeks, and 6 at 10 weeks. Both histopathologic and hematologic studies were performed every week. RESULTS: By 4 weeks after the steroid injection, 43% of the rabbits studied had developed multifocal ON lesions in the femur and/or humerus. In 1 rabbit, a thrombus was detected in an arteriole adjacent to the necrotic area at 4 weeks. After 6 weeks, there was also progressive histologic evidence of revascularization, with granulation tissue, and osteoblastic repair, with appositional bone formation. Hyperlipemia, fatty liver, and intraosseous fat embolism were observed in conjunction with thrombocytopenia and hypofibrinogenemia. CONCLUSION: A single injection of high-dose corticosteroids was found to be capable of inducing thrombocytopenia, hypofibrinogenemia, and hyperlipemia with multifocal ON in several bones.

Extraskeletal chondroma with chondroblastic and granuloma-like elements.

A unique case of extraskeletal chondroma occurring in the right ring finger of a 51-year-old man is reported. The tumor, measuring 4.0 x 2.2 x 1.5 cm, consisted of chondroid, granuloma-like, and chondroblastic cell zones associated with fine calcification. Immunohistochemically, most of the tumor cells except for multinucleated giant cells were positive for vimentin. Cells positive for S-100 protein were scattered throughout the tumor, and cells positive for alpha-1 antichymotrypsin were observed in the chondroblastic cell zone and in the granuloma-like area. Ultrastructurally, the chondroblastic cells had a characteristic microvillous cell border.

Dye clearance studies in Rotor's syndrome.

Plasma clearances of sulfobromophthalein sodium (BSP), indocyanine green (ICG) and unconjugated bilirubin were studied in six patients with Rotor's syndrome. A marked retention of these three substances in the plasma was observed. At 60 minutes after injection, serum BSP consisted almost entirely of the unconjugated form. In three patients, BSP Tm and BSP S were significantly reduced. Clearance of unconjugated bilirubin was markedly impaired. This, together with the conjugated hyperbilirubinemia may be interpreted to reflect reduced storage. These results indicate that Rotor's syndrome is marked by reduced hepatic storage capacity and excretory function of BSP, ICG and bilirubin.

Serum cholesterol and squalene in hepatocellular carcinoma.

In 15 patients with hepatocellular carcinoma, the serum squalene level is raised significantly in parallel with the serum cholesterol level, though significantly decreased in patients with cholestatic hepatobiliary disease. Serum levels of cholesterol and/or squalene, therefore, could be regarded as a laboratory index reflecting a peculiar sterol metabolism in hepatocellular carcinoma.

Value of B-scan ultrasonography in the diagnosis of liver cancer. Accuracy compared to scintigraphy and angiography.

Seventy-one patients with liver cancer were examined by B-scan ultrasonography. The presence of liver cancer was assumed through the irregularity and increased intensity of echos. The accuracy of ultrasonography in the diagnosis of liver cancer was 72%, while the diagnostic accuracy of scintigraphy was 85% and angiography 93%. No obvious correlation could be demonstrated between the ultrasonographic patterns and serum alpha-fetoprotein (AFP) levels. Ultrasonography is a useful method of detecting liver cancer.

Effect of corticosteroid treatment on bilirubin metabolism in chronic aggressive hepatitis.

The metabolism of unconjugated bilirubin from the plasma was studied in 17 patients with chronic hepatitis and 7 normal subjects following a single injection of bilirubin of 2 mg per kg body weight. From the plasma disappearance curves of unconjugated bilirubin, hepatic uptake, reflux from the liver to the plasma and hepatic conjugation were calculated by 2 compartmental analysis. The clearance remained within normal range in 5 patients with chronic persistent hepatitis but was significantly impaired in 12 patients with chronic aggressive hepatitis, in which corticosteroid treatment improved the clearance significantly (p less than 0.01). Since urinary excretion of d-glucaric acid remained unchanged by corticosteroid treatment, the improved clearance may be attributable to increased hepatic parenchymal function.

Diagnostic significance of fasting serum bile acid in liver disease.

Serum bile acid was extracted with Amberlite XAD-2 followed by determination with an enzymatic and fluorimetric technique. Normal value for fasting serum bile acid was found to be 3 +/- 2 muM. Serum bile acid level was raised markedly early in the course of acute viral hepatitis, subsequently fell rapidly before resolution of biochemical tests, and was elevated again in relapse. In chronic liver disease serum bile acid was elevated moderately and correlated roughly with disease severity. In comparison with routine biochemical tests, serum bile acid correlated significantly with serum bilirubin, BSP retention and other hepatic tests, except serum cholesterol. Thus fasting serum bile acid level is a reliable screening test for a variety of liver disease to assess functional and morphological impairment of the liver.

Serum cholesterol and bile acid in primary hepatoma.

The close relationship between serum levels of cholesterol and bile acid has been confirmed in 46 patients with primary hepatoma. Serum levels of cholesterol and bile acid are roughly correlated with serum alpha-fetoprotein concentration. Because the relationship between serum cholesterol and bile acid did not exist in common hepatocellular diseases, the results suggest a peculiar sterol metabolism occurring in human hepatoma.

Studies on the relationship of hepatic anion-binding proteins and sulfobromophthalein-glutathione conjugation in normal and phenobarbital-treated rats.

The enzyme activity which conjugates sulfobromophthalein with glutathione was separated from rat liver supernate by Sephadex G-75 gel filtration, and assayed by two different methods; paper electrophoresis and spectrophotometry. The enzyme activity was found mainly in the second protein fraction, and less than 5% of the activity in the first or third protein fractions. In vitro mixtures of sulfobromophthalein, [3-H]glutathione and rat liver supernate showed that the major part of [3-H]glutathione was detected in the first and second protein fractions, and the remainder in the third protein fraction. Phenobarbital treatment caused an increase of the enzyme activity, sulfobromophthalein and [3-H]glutathione, in the second protein fraction.