Factors Affecting the Second Complete Atypical Femoral Fracture after the First Atypical Fracture

OBJECTIVES

Atypical femoral fracture (AFF) is an atypical low-energy subtrochanteric and diaphyseal femoral fracture. Even if bone fusion is achieved in patients with AFF, the risk of AFF in the contralateral femur must be considered. This study aimed to investigate the factors affecting complete AFF in the contralateral femur and conservatively treated incomplete AFF.

SUBJECT AND METHODS

Radiographs of 111 femurs in 104 AFF cases were examined, and the femurs were classified as follows: 85 contralateral femurs with complete AFF; 18 contralateral femurs with incomplete AFF; 8 femurs with incomplete AFF without surgical treatment. Various patients' clinical data were collected, and we investigated the factors affecting the second complete AFF.

RESULTS

Complete fractures occurred in 10 (9.7%) of 103 femurs without incomplete AFF at the first visit and in 3 (37.5%) of 8 femurs with incomplete AFF. The Kaplan-Meier curve revealed that lateral cortical bone thickening and thigh pain were associated with significantly poorer prognoses (p = 0.026 and p = 0.013, respectively). Multivariate analyses revealed that eldecalcitol usage after AFF onset (p = 0.0094) and previous use of bisphosphonate or denosumab (p = 0.0126) were protective factors for second complete AFF and that the presence of thigh pain (p = 0.0134) was a risk factor for second complete AFF.

CONCLUSIONS

Eldecalcitol administration after bone union of first AFF may prevent AFF recurrence. In addition, painful incomplete AFF has a high risk of developing a complete fracture.

Evaluation of Medial Meniscal Extrusion Using Radiography

Recently, there has been increasing interest in medial meniscal extrusion (MME), but few reports have evaluated MME via X-ray. In this study, the amount of MME and meniscal height at the medial border of the tibia were measured via X-ray with gradation processing. The extrusion length divided by the meniscal height yields the meniscal extrusion ratio, which was used as an index. In addition, the medial meniscal length of the part protruding from the medial border of the tibia on MRI was measured as an absolute value. Then, the correlation between the meniscal extrusion ratio and the amount of MME on MRI was examined, and there was a strong correlation between the meniscal extrusion ratio via X-ray and the amount of MME on MRI (correlation coefficient 0.860, p < 0.0001). The cut-off value of the meniscal extrusion ratio via X-ray for positive meniscal extrusion on MRI was 0.50, with an AUC of 0.9825, sensitivity of 0.9063, and specificity of 0.8663. From the present study, it was possible to measure the extrusion length and meniscal height via gradation processing, with X-ray and without MRI, and to calculate the meniscal extrusion ratio, which strongly correlates with the amount of MME on MRI.

A Novel Classification of Coronal Plane Knee Joint Instability Using Nine-Axis Inertial Measurement Units in Patients with Medial Knee Osteoarthritis

The purpose of this study was to propose a novel classification of varus thrust based on gait analysis with inertial motion sensor units (IMUs) in patients with medial knee osteoarthritis (MKOA). We investigated thigh and shank acceleration using a nine-axis IMU in 69 knees with MKOA and 24 (control) knees. We classified varus thrust into four phenotypes according to the relative medial-lateral acceleration vector patterns of the thigh and shank segments: pattern A (thigh medial, shank medial), pattern B (medial, lateral), pattern C (lateral, medial), and pattern D (lateral, lateral). Quantitative varus thrust was calculated using an extended Kalman filter-based algorithm. We compared the differences between our proposed IMU classification and the Kellgren-Lawrence (KL) grades for quantitative varus thrust and visible varus thrust. Most of the varus thrust was not visually perceptible in early-stage OA. In advanced MKOA, increased proportions of patterns C and D with lateral thigh acceleration were observed. Quantitative varus thrust was significantly increased stepwise from patterns A to D. This novel IMU classification has better clinical utility due to its ability to detect subtle kinematic changes that cannot be captured with conventional motion analysis even in the early stage of MKOA.

Successful Treatment of Atypical Femoral Fracture with Bowed Femur Using Contralateral Intramedullary Nail Combined with Early Daily Teriparatide

We report a case of atypical femoral fracture achieving early fracture union with combination therapy comprising contralateral nail and immediate teriparatide injection. Fracture union of atypical fractures is often delayed due to bowing deformity and bone metabolic disorders. Combination treatment that takes both problems into consideration represents a useful treatment option for atypical femoral fracture.

Fibrin monomer complex on postoperative day 1 is correlated with the volume of deep vein thrombosis after knee surgery

PURPOSE

Patients undergoing knee surgery are at high risk for deep vein thrombosis (DVT), which is infrequent but potentially life-threatening. It has not been identified how to efficiently detect high-risk DVT while minimizing bleeding complications from anticoagulation. We hypothesized that the degree of activation of thrombotic markers may correlate with the size of the thrombus. Therefore, we investigated the correlation between thrombotic markers and DVT thrombus volume in patients after knee surgery.

METHODS

This retrospective study involved 29 patients who underwent around knee osteotomy or total / unicompartmental knee arthroplasty from 2018 to 2020. Fibrin monomer complex (FMC) at 1, and 7 days after surgery, and D-dimer at 4, and 7 days after surgery were investigated. In addition, the volume of DVT was estimated with ultrasonography at the 7 days after surgery. Body mass index, surgical time, and total volume of blood loss were also evaluated. Factors related to thrombus volume were examined statistically.

RESULTS

Nine patients (31.0%) exhibited asymptomatic distal DVT, whereas 1 patient (3.4%) experienced asymptomatic proximal DVT. No patients had pulmonary embolism. Statistical analysis showed that only FMC concentration on postoperative day 1 was significantly correlated with thrombus volume (p <  0.001, 95% confidence interval 0.41 to 0.839, r = 0.679).

CONCLUSIONS

The FMC concentration was a useful early indicator of deep vein thrombosis after knee surgery. Monitoring the FMC concentration could enable selective identification of patients with a high thrombus volume, which is associated with a high risk for pulmonary embolism.

Diagnostic Accuracy of the Mobile Assessment of Varus Thrust Using Nine-axis Inertial Measurement Units

Objectives:

The purpose of this study was to clarify the diagnostic accuracy of the mobile assessment of varus thrust using inertial measurement units (IMUs).

Methods:

A total of 80 knees in 49 patients were enrolled in this study. On visual analysis of gait to determine the presence or absence of varus thrust, 23 knees were assigned to the Present group, 17 to the Ambiguous group, and 40 to the Absent group. The peak knee varus angular velocities (PVVs), measured by quantitative gait analysis using nine-axis IMUs, were compared between these three groups. A receiver operating characteristic curve for the relationship between the visual assessment of varus thrust (Present and Ambiguous) and the measured PVV was created, and the cut-off PVV for visualized varus thrust was determined as the highest point for both sensitivity and specificity.

Results:

The mean PVVs were significantly different between the three groups (Present, 47.7 ± 8.2 degree/s, Ambiguous, 34.1 ± 10.5 degree/s, and Absent, 28.1 ± 8.3 degree/s, respectively, ANOVA P=0.000). The PVV cut-off value for visualized varus thrust was 28.1 degree/s, yielding a sensitivity of 0.957 and a specificity of 0.579.

Conclusions:

A PVV <28.1 degree/s is useful for ruling out varus thrust during gait. This quantitative varus thrust assessment method using IMUs has clinical utility as a screening test.

Evaluation of factors affecting the occurrence of second atypical fracture after bone union of the first atypical fracture

PURPOSE

Teriparatide is sometimes used in the treatment of atypical femoral fracture (AFF). Even if bone union is achieved, orthopedic physicians must consider the risk of relapse. This study aimed to investigate the factors affecting AFF recurrence, and to determine the appropriate treatment for osteoporosis after bone union.

METHODS

One hundred thirty-one consecutive AFFs in 113 Japanese patients were included. Eleven patients had AFF in the unaffected limb (9 patients) after the first AFF or re-fracture at the original fracture site (2 patients) after bone union of the first AFF was confirmed. We divided all patients into two groups: the second fracture group (22 AFFs in 11 patients) and non-second fracture group (109 AFFs in 102 patients). We compared clinical information between the 2 groups and investigated the factors affecting AFF recurrence using the Student t-, Welch t-, and chi-square tests.

RESULTS

Although there was no significant difference in clinical characteristics between the 2 groups, multivariate analysis of factors associated with AFF recurrence identified short duration of treatment with teriparatide and active vitamin D₃ (p = 0.0408 and 0.0366, respectively) as risk factors. Even in the analysis excluding subtrochanteric AFF, short periods of teriparatide and active vitamin D₃ administration were observed as risk factors (p = 0.0484 and 0.0346, respectively).

CONCLUSION

The administration of teriparatide for as long as possible after occurrence first AFF and the use of active vitamin D₃ after completion of teriparatide therapy may be the most effective strategy to prevent the recurrence of AFF.

Evaluation of the Nature and Etiologies of Risk Factors for Diaphyseal Atypical Femoral Fractures

OBJECTIVES

Differences in mechanisms of subtrochanteric and diaphyseal atypical femoral fractures (AFFs) are speculated in studies that analyzed differences in the patients' background. However, the etiologies of each type of AFF have not been studied in detail. This study aimed to investigate the nature and etiologies of the risk factors for diaphyseal AFFs.

MATERIALS AND METHODS

Eighty consecutive Japanese patients with 91 diaphyseal AFFs (AFF group) and 110 age-matched women with osteoporosis (non-AFF control group) were included. Their clinical data were compared; factors affecting AFFs were investigated, and the etiologies of the risk factors for diaphyseal AFFs were examined.

RESULTS

Multivariate analysis revealed that femoral serrated changes, bisphosphonate or denosumab usage, and lateral and anterior femoral curvatures were risk factors for diaphyseal AFFs (p < 0.0011, p = 0.0137, and p < 0.0001, respectively). Multivariate analyses revealed that serrated changes and low serum 25(OH)D levels affected the lateral curvature (p = 0.0088 and 0.0205, respectively), while serrated changes affected the anterior curvature (p = 0.0006), each significantly affected the femoral curvature. High serum calcium (Ca) levels, lateral femoral curvature, and anterior femoral curvature were predictors of serrated changes (p = 0.0146, 0.0002, and 0.0098, respectively).

CONCLUSION

Risk factors for diaphyseal AFFs were bone resorption inhibitor usage, a strong femoral curvature, and serrated changes. Low serum 25(OH)D levels and serrated changes are risk factors for lateral curvature, while a high serum Ca level is a risk factor for serrated changes.

Radiographic deformities of the lower extremity in patients with spontaneous osteonecrosis of the knee

BACKGROUND

Spontaneous osteonecrosis of the knee (SONK) is one of the acute knee pain disorders arising in elderly patients. The presence of knee varus alignment and the size of necrotic area have been reported as the negative prognostic factors in prior studies. However, no previous study has yet clarified the radiological analysis of the lower extremity in SONK compared with that in osteoarthritis. The purpose of this study was therefore to identify the radiographic findings of the lower extremity in SONK.

METHODS

Sixty-three knees of Kellgren-Lawrence classification grade 1 or 2 without any trauma treated between April 2012 and March 2014 were enrolled in this study. These knees were divided into two groups according to their magnetic resonance imaging (MRI) findings: SONK group (31 knees) and OA group (32 knees). Using a long leg standing X-ray, femorotibial angle (FTA), mechanical axis deviation (MAD), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA) and joint line convergent angle (JLCA) were compared between groups. Correlation between each parameter and the width ratio (WR) of the necrotic lesion were analyzed.

RESULTS

FTA, MAD, MPTA and JLCA showed significant differences between the SONK and OA groups. In the SONK group, FTA was positively correlated with WR, and, MAD and MPTA was negatively correlated with WR.

CONCLUSIONS

Compared with OA, SONK is associated with a significantly larger varus deformity at the proximal tibia, and larger joint play in the coronal plane.

Diagnosis of Presarcopenia Using Body Height and Arm Span for Postmenopausal Osteoporosis

Purpose

Sarcopenia and osteoporosis are both serious health problems in postmenopausal women. The Asia Working Group for Sarcopenia recommends using the skeletal muscle index (SMI), which is height-adjusted appendicular skeletal muscle mass (ASMM). However, loss of height has been shown to be a common clinical finding in patients with osteoporosis. This study examined the prevalence of presarcopenia using height and arm span, which is a predictor of height, and investigated the diagnostic accuracy for presarcopenia.

Methods

A total of 55 post-menopausal osteoporotic patients aged 62-95 years underwent bioelectrical impedance analysis (BIA) for ASMM measurement and dual-energy X-ray absorptiometry (DXA) scan for bone mineral density (BMD). Anthropometric measurements, including height, weight, and arm span were taken, and body mass index (BMI), SMI, and arm span-adjusted SMI (Arm span SMI) were calculated. Presarcopenia was defined as SMI or Arm span SMI <5.7 kg/m² in this study.

Results

The prevalence of presarcopenia was 27.3% and 38.2% evaluated by SMI and Arm span SMI, respectively. The prevalence of presarcopenia was higher when evaluated by Arm span SMI than by SMI. In the presarcopenia group diagnosed only by Arm span SMI (n=11), the arm span-height difference was significantly higher (p<0.001) and the percentage of young adult mean (YAM) femoral neck-BMD was significantly lower (p=0.013) compared to the normal group diagnosed by both SMI and Arm span-SMI (n=29).

Conclusion

These results indicated that Arm span SMI might be useful for the diagnosis of sarcopenia in patients with severe osteoporosis and kyphosis.

Effects of bazedoxifene and low-intensity aerobic exercise on bone and fat parameters in ovariectomized rats

INTRODUCTION

Postmenopausal osteoporosis and dyslipidemia are well-known skeletal and metabolic changes in middle-aged women. We investigated the effects of combined treatments with a selective estrogen receptor modulator (SERM) and exercise on bone and fat parameters in ovariectomized (OVX) rats.

MATERIALS AND METHODS

Sixteen-week-old female Sprague-Dawley rats underwent bilateral ovariectomy, and rats were randomized to BZA (bazedoxifene at 0.3 mg/kg/day), Exe (treadmill exercise at 12-15 m/min, 60 min/day, 5 days/week), Comb (BZA and Exe), and Cont (control treated with vehicle and no exercise) groups 8 weeks after ovariectomy. After 4 or 8 weeks of treatment, bone mineral density (BMD) of the total femur and lumbar spine and whole-body percentage fat mass were determined by dual-energy X-ray absorptiometry, and mechanical testing of the femoral shaft, and bone and fat histomorphometric analyses of the proximal tibia were performed.

RESULTS

Treadmill exercise had decreased bone marrow adipocytes from 4 weeks of treatment and whole-body percentage fat mass at 8 weeks. BZA increased BMD at the lumbar spine and decreased the whole-body percentage fat mass from 4 weeks and bone marrow adipocytes at 8 weeks. Combination therapy increased BMD for the lumbar spine and decreased bone marrow adipocytes and whole-body percentage fat mass from 4 weeks.

CONCLUSION

Combination therapy with BZA and exercise appears effective to improve bone and fat parameters in OVX rats.

Micro-CT imaging analysis for the effects of ibandronate and eldecalcitol on secondary osteoporosis and arthritis in adjuvant-induced arthritis rats

We investigated the effects of ibandronate, a bisphosphonate; eldecalcitol, an active vitamin D3 analogue; and combination treatment with both agents on secondary osteoporosis and arthritis using rats with adjuvant-induced arthritis. Arthritis was induced in 8-week-old male Lewis rats. Rats were randomized into four treatment groups and an untreated normal control group: ibandronate, eldecalcitol, ibandronate + eldecalcitol, vehicle, and control. Paw thickness was measured to evaluate arthritis. Joint destruction was evaluated histomorphometrically by the ankle joint stained with Fast Green and safranin O. The femur and lumbar spine were scanned using dual-energy X-ray absorptiometry, and the distal femur was scanned using micro-computed tomography for bone mineral density (BMD) and trabecular microstructural evaluations. Ibandronate and/or eldecalcitol increased BMD in both the lumbar vertebrae and femur and improved several microstructural parameters (bone volume/total volume, structure model index, trabecular number, and trabecular separation of the distal femur). In addition, there was an additive effect of combination treatment compared with single treatments for most trabecular parameters, including BMD and bone volume. However, ibandronate and/or eldecalcitol did not inhibit arthritis and joint destruction. Combination treatment with ibandronate and eldecalcitol may be effective for secondary osteoporosis associated with arthritis.

Effects of eldecalcitol and ibandronate on secondary osteoporosis and muscle wasting in rats with adjuvant-induced arthritis

Objectives

Rheumatoid arthritis (RA) is characterized by chronic inflammation of the synovium, progressive erosion of the articular cartilage, and joint destruction. RA also causes secondary osteoporosis and muscle wasting. We investigated the effects of ibandronate (IBN), a bisphosphonate; eldecalcitol (ELD), an active vitamin D3 derivative; and combination treatment with both agents on secondary osteoporosis and muscle wasting using adjuvant-induced arthritis rats.

Methods

Arthritis was induced in 8-week-old male Lewis rats. Rats were randomized into 4 treatment groups and an untreated normal control group: IBN (subcutaneously, once every 2 weeks, 10 μg/kg), ELD (orally, once daily, 30 ng/kg/day), IBN + ELD, vehicle, and control. Paw thickness measurements were performed for evaluation of arthritis. The femur was scanned using dual-energy X-ray absorptiometry. Cross-sectional areas of left tibialis and anterior muscle fibers and the expression of MuRF1, atrogin-1, MyoD, and myogenin in the gastrocnemius muscle were measured to evaluate muscle wasting.

Results

IBN and/or ELD increased bone mineral density (BMD) in the femur. In addition, there was an additive effect of combination treatment compared with single treatments for BMD. However, IBN and/or ELD did not inhibit muscle wasting in adjuvant-induced arthritis rats.

Conclusions

Combination treatment with IBN and ELD may be effective for secondary osteoporosis associated with RA. Other treatments are necessary for muscle wasting associated with RA. Studies in humans are needed to confirm these findings.

Effects of activated vitamin D, alfacalcidol, and low-intensity aerobic exercise on osteopenia and muscle atrophy in type 2 diabetes mellitus model rats

Diabetes mellitus causes secondary osteoporosis and muscle atrophy. The ability of alfacalcidol (ALF) and exercise (Exe) to inhibit osteoporosis and muscle atrophy in type 2 diabetes mellitus (T2DM) model rats was examined. Twenty-week-old Otsuka Long-Evans Tokushima Fatty rats were randomized to ALF (orally 0.1 μg/kg/day), Exe (treadmill exercise at 10 m/min, 60 min/day, 5 days/week), Comb (ALF and Exe), and Cont (T2DM control treated with vehicle and no exercise) groups (n = 8–10 per group). Sedentary Long-Evans Tokushima Otsuka rats were used as a non-hyperphagic control. After treatment for 2 or 6 weeks, blood glucose (BG) levels, cross-sectional area (CSA) of tibialis anterior muscle fibers, femoral bone mineral density (BMD), and relative quantities of muscle anabolic markers (Pax7, MyoD, and myogenin) and catabolic markers (Atrogin-1, MuRF1, and REDD1) of the soleus muscle assessed by real-time polymerase chain reaction assays were measured. Exe and Comb treatments for 6 weeks decreased BG levels compared with those of the Cont group. ALF, Exe, and Comb treatments for 2 and 6 weeks recovered the CSA compared with that of the Cont group. ALF and Comb treatments for 6 weeks increased femoral BMDs compared with those of the Cont group. After 2 weeks of treatment, Comb treatment increased MyoD expression and decreased MuRF1 expression. ALF or Exe monotherapy significantly decreased Atrogin-1 or MuRF1 expression after 2 weeks of treatment, respectively. After 6 weeks of treatment, ALF and Comb treatments decreased Atrogin-1 and REDD1. These results demonstrate that a combination of ALF and Exe improved CSA from the early phase of treatment by stimulating skeletal muscle differentiation and suppressing muscle catabolic genes. Improvements in BG, BMD, and CSA were observed as long-term effects of the combination therapy. Continued suppression of muscle catabolic genes was observed as a background to these effects.

Effects of combined therapy of alendronate and low-intensity pulsed ultrasound on metaphyseal bone repair after osteotomy in the proximal tibia of glucocorticoid-induced osteopenia rats

Objectives

Glucocorticoid (GC) treatment inhibits activation of runt-related transcription factor 2 (Runx2), which is essential for osteoblast differentiation from stem cells. As a result, GC treatment results in bone loss, GC-induced osteoporosis (GIO), elevated fracture risk, and delayed bone healing. Bisphosphonates such as alendronate (ALN) are recommended for treating or preventing GIO, and low-intensity pulsed ultrasound (LIPUS) facilitates fracture healing and maturation of regenerated bone. Combined therapy with ALN and LIPUS may stimulate cancellous bone healing in GIO rats. Here, we examined the effect of ALN and LIPUS on cancellous bone osteotomy repair in the proximal tibia of GIO rats.

Methods

Prednisolone (10 mg/kg body weight/day) was administered for 4 weeks to induce GIO in 6-month-old female Sprague-Dawley rats. Tibial osteotomy was then performed and daily subcutaneous injection of ALN (1-μg/kg body weight) was subsequently administered alone or in combination with LIPUS (20 min/day) for 2 or 4 weeks.

Results

ALN significantly increased bone mineral density (BMD) at 2 and 4 weeks, and ALN + LIPUS significantly increased BMD at 4 weeks. Bone union rates were significantly increased after 2 and 4 weeks ALN and ALN + LIPUS treatment. Lastly, ALN and ALN + LIPUS significantly increased the proportion of Runx2 positive cells at 4 weeks.

Conclusions

ALN monotherapy and combined ALN and LUPUS treatment augmented BMD and stimulated cancellous bone repair with increased Runx2 expression at the osteotomy site in GIO rats. However, the combined treatment had no additional effect on cancellous bone healing compared to ALN monotherapy.

Vertebral osteomyelitis and epidural abscess caused by gas gangrene presenting with complete paraplegia: a case report

Introduction

Gas gangrene is most often caused by Clostridium perfringens infection. Gas gangrene is a medical emergency that develops suddenly. The mortality rate is higher with trunk involvement than with involvement of the extremities, which carries a better prognosis. With respect to vertebral involvement, there are few reports in the literature. The purpose of this paper is to report a very rare case of vertebral osteomyelitis caused by gas gangrene.

Case presentation

A 78-year-old Japanese woman with diabetes mellitus was admitted to our hospital with the chief complaints of back pain, dysuria, and complete paralysis of both legs. A computed tomography scan showed soft tissue swelling anterolaterally at intervertebral disc level T11/12 and a gas-containing epidural abscess that compressed her spinal cord. Cultures later grew Clostridium perfringens and Escherichia coli. Hemilaminectomy was done from T10 to T12, and an epidural abscess was removed. She went on to have fusion surgery 6 weeks after the initial operation and subsequently experienced complete pain relief. She was discharged 2 months later, at which time she was able to walk with a cane. Examination 18 months after surgery showed normal gait without a cane.

Conclusions

Discitis caused by gas gangrene infection was successfully treated by immediate debridement and subsequent fusion surgery.

Mechanism of formation of elastin crosslinks

We examined the formation of quaternary pyridinium crosslinks of elastin formed by condensation of lysine and allysine residues using the model compounds propanal (allysine) and n-butylamine (lysine) under quasi-physiological conditions. The resulting pyridinium compounds were characterized and the structure compared with the known pyridinium crosslinks. Three pyridinium compounds were identified and the structures were identical with the skeleton of the crosslinking amino acids, desmosine (DES), isodesmosine (IDE), and pentasine. We concluded that a non-enzymatic pathway is available for the spontaneous generation of pyridinium crosslinks. To elucidate the intermediates and the mechanism of the formation of DES and IDE, we synthesized model intermediates from propanal and n-butylamine, and they were allowed to react in three kinds of solvents. Then, the products were analyzed by an ion-pair reverse-phase HPLC. The results of this model system indicated that DES and IDE can be formed by condensation of dehydromerodesmosine with dehydrolysinonorleucine and by condensation of allysine with dehydrolysinonorleucine, respectively. We also describe the mechanism of DES and IDE crosslinking.

Amine oxidase-like activity of polyphenols. Mechanism and properties

Polyphenols in several oxidation systems gained amine oxidase-like activity, probably due to the formation of the corresponding quinones. In the presence of Cu(II), o- and p-phenolic compounds exhibited amine oxidase-like activity, whereas only the o-phenolic compounds showed the activity in the presence of 1,1-diphenyl-2-picrylhydrazyl radical. The activity was determined by measuring the conversion of benzylamine to benzaldehyde by HPLC. Moreover, gallic acid, chlorogenic acid, and caffeic acid, which are plant polyphenols, converted the lysine residue of bovine serum albumin to alpha-amino-adipic semialdehyde residue, indicating lysyl oxidase-like activity. We also characterized the activity of pyrocatechol, hydroquinone, and pyrogallol in the presence of Cu(II). The oxidative deamination was accelerated at a higher pH, and required O2 and transition metal ions. Furthermore, EDTA markedly inhibited the reaction but not beta-aminopropionitrile, which is a specific inhibitor of lysyl oxidase. Catalase significantly inhibited the oxidation, implying the participation of hydroxyl radical in the reaction, but superoxide dismutase stimulated the oxidation, probably due to its radical formation activity. We discussed the mechanism of the oxidative deamination by polyphenols and the possible significance of the activity for biological systems.

Characterization of a model compound for the lysine tyrosylquinone cofactor of lysyl oxidase

We characterized a model compound for the lysine tyrosylquinone (LTQ) cofactor of lysyl oxidase which is one of the mammalian copper-dependent amine oxidases. The model compound, 4-butylamino-5-methyl-o-quinone, was prepared from n-butylamine and 4-methylcatechol by the oxidation with sodium iodate and characterized by spectroscopic analyses. The absorption maximum at 494 nm is consistent with that of lysyl oxidase. The model compound was capable of deaminating benzylamine to benzaldehyde at 37 degrees C in buffered aqueous acetonitrile. The aldehyde production was markedly elevated in the presence of the Cu(II)-EDTA complex but inhibited by free Cu(II). The catalytic cycle was observed at pH 10 in the presence of Cu(II), and the pH activity profile showed a broad optimum at about pH 9.0. In the presence of beta-aminopropionitrile and upon deoxygenation with N2 aldelyde, production was decreased. The important features of the reaction were consistent with the enzymatic reaction.

Cyclopentenosine, major trifunctional crosslinking amino acid isolated from acid hydrolysate of elastin

A trifunctional crosslinking amino acid named cyclopentenosine (CP) was isolated from the hydrolysate of bovine nuchal ligament elastin. CP and its derivatives were identified by spectroscopic methods. CP was found to consist of a 2-cyclopenten-1-one structure and its imine-enamine tautomers with enantiomers in H(2)O. A model reaction for the formation of the CP crosslink using model compounds for allysine (propanal) and lysine (n-butylamine) demonstrated that CP is composed of 2-cyclopenten-1-one and alpha, beta, gamma, delta-unsaturated aldehyde derived from three allysine residues. An ion-paired high-performance liquid chromatographic method for the determination of CP was developed. Among various bovine tissues the nuchal ligament had the highest concentration of CP. The age-related changes in the concentration of CP were examined in the aorta from rat (short-lived species) and bovine (long-lived species). The CP content was very low in the newborn rat but increased markedly with growth. After maturity, the CP content remained nearly the same or slightly decreased. In bovine aorta, the CP content scarcely changed from 7 months to 16 years.

Lysyl oxidase coupled with catalase in egg shell membrane

The activity of lysyl oxidase was found in egg shell membrane (ESM) of hens. The activity was determined by measuring the enzymatic conversion of n-butylamine and Nalpha-acetyl-L-lysine to n-butyraldehyde and Nalpha-acetyl-L-allysine, respectively. ESM lysyl oxidase was significantly inhibited by beta-aminopropionitrile, chelating agents, and deoxygenation, consistent with the known properties of lysyl oxidase. Nevertheless, ESM lysyl oxidase was insoluble in urea solution, suggesting that it complexes with ESM. These findings support previous reports indicating the presence of lysine-derived cross-links in ESM and the necessity of lysyl oxidase located in the isthmus of the hen oviduct for the biosynthesis of ESM. Lysyl oxidase secreted around the egg white from the isthmus may initiate the cross-linking reaction of ESM protein, and remain as the constituent of ESM. Moreover, the H(2)O(2) released by lysyl oxidase in ESM was completely decomposed by coexisting catalase activity. ESM lysyl oxidase activity was greatly elevated in the presence of H(2)O(2), probably due to the O(2) produced by catalase. These findings indicate that lysyl oxidase is coupled with catalase in ESM. This coupling enzyme system was considered to be involved in the biosynthesis of ESM and to protect the embryo against H(2)O(2).

Specific measurement of a major mite allergen, Der f II, by an enzyme-linked immunosorbent assay system using monoclonal anti-Der f II antibodies

An enzyme linked immunosorbent assay system using a monoclonal antibody, 15E11, specific for a major allergen Der f II in house dust mite, was developed. This system detected only Der f II in the presence of Der p II and other allergens. The Der f II contents in several house dust samples significantly correlated with the numbers of the mites in the same house dust samples (n = 14, r = 0.88, p < 0.001). These data showed that this system was useful for specific measurement of Der f II in house dusts.

Preparation of specific monoclonal antibodies against Der f II one of the major allergens of Dermatophagoides farinae

Five monoclonal antibodies (Mabs) against Der f II, one of the major allergens of Dermatophagoides farinae, were obtained from mice immunized with the allergen. Western blotting analysis revealed that only one Mab, named 15E11, was specific for Der f II, whereas the other Mabs crossreacted with Der p II, one of the major allergens of Dermatophagoides pteronyssinus. These results indicate the possibility that the Der f II-specific Mab, 15E11, is a useful reagent for specific determination of Der f II.

Purification and properties of restriction endonuclease from Deleya marina IAM 14114, a marine bacterium (DmaI)

A restriction endonuclease, designated as DmaI, was purified from cell-free extracts of Deleya marina IAM 14114 by streptomycin treatment, ammonium sulfate fractionation and two steps of chromatographies on heparin-Sepharose CL-6B and Mono Q (HR 5/5, FPLC). The purified enzyme was homogeneous on SDS-polyacrylamide gel disk electrophoresis and a ligation-recutting test. The relative molecular mass measurements of the purified enzyme gave 28,000 daltons by SDS-polyacrylamide gel disk electrophoresis and 56,000 daltons by gel filtration. These data indicated that the purified enzyme (56,000 daltons) has a dimeric structure composed of two 28,000-dalton subunits. The isoelectric point was 5.5. The purified enzyme worked best at 37 degrees C in a reaction mixture (50 microliters) containing 1.0 micrograms lambda DNA, 10 mM Tris-HCl, 7 mM 2-mercaptoethanol, 7 mM MgCl2 and 100 mM NaCl (pH 7.5). The enzyme was stable up to 55 degrees C and between pH 7.0 and 9.0. The purified enzyme recognizes the palindromic hexanucleotide DNA sequence 5'-CAGCTG-3', cuts between G and C and produces a flush end (isoschizomer of PvuII).

Purification, properties and determinations of recognition sequence and cleavage site of restriction endonuclease from "Agrobacterium gelatinovorum" IAM 12617, a marine bacterium (AgeI)

A new restriction endonuclease, designated as AgeI, was purified from cell-free extracts of a marine bacterium, "Agrobacterium gelatinovorum" IAM 12617 by streptomycin treatment, ammonium sulfate fractionation, combined column chromatographies on heparin-Sepharose CL-6B and DEAE-Sepharose CL-6B and FPLC on Mono Q (HR 5/5) and Superose 12 (HR 10/30). The purified enzyme was homogeneous on SDS-polyacrylamide gel disc electrophoresis and free from other phosphatase and exonuclease activities on ligation-recutting test. The relative molecular mass of the enzyme was 24,000 daltons by SDS-polyacrylamide gel disc electrophoresis. The gel filtration using Superose 12 (HR 10/30) gave the same calculation (23,000 daltons). These data indicated that the enzyme is a monomer. The isoelectric point of the enzyme was 6.5. The purified enzyme cleaved lambda and Ad2 DNAs at 10 or more and 5 sites, respectively. However, the purified enzyme did not cleave SV40, phi X174 RF I, M13mp 18 RF I or pBR322 DNAs. pBR328 DNA was cleaved at 1 site by the purified enzyme. The purified enzyme worked best at 37 degrees C and pH 7.5 in a reaction mixture (50 microliters) containing 1.0 micrograms lambda DNA, 10 mM Tris-HCl, 7 mM 2-mercaptoethanol, 7 mM MgCl2 and 50 mM NaCl. The purified enzyme did not require monovalent cations necessarily for the enzyme reaction. The enzyme recognized the palindromic hexanucleotide DNA sequence 5'-ACCGGT-3' and cut between A and C, producing a 5'-cohesive tetranucleotide extension.