Bisphosphonate Treatment Increases the Size of the Mandibular Condyle and Normalizes Growth of the Mandibular Ramus in Osteoprotegerin-Deficient Mice

Osteoprotegerin (OPG) is a novel secreted member of the tumor necrosis factor receptor family which plays a crucial role in negative regulation of osteoclastic bone resorption. OPG-deficient (OPG–/–) mice develop severe osteoporosis caused by significant enhancement of bone resorption by osteoclasts. We investigated the effect of administering bisphosphonate on mandibular growth and development in OPG–/– mice. Eight-week-old male OPG–/– mice and wild-type (WT) mice were administered bisphosphonate (1.25 mg/kg body weight) intraperitoneally once every 3 days for 30 days. All bone formation-related parameters and bone resorption-related parameters were significantly lower in OPG–/– mice with bisphosphonate than in those without bisphosphonate. The volume of the whole condyle and the mandibular length in OPG–/– mice without bisphosphonate were significantly smaller than in WT mice without bisphosphonate. Bisphosphonate treatment of the OPG–/– mice resulted in an increase in the volume of the mandibular condyle and mandibular ramus length. In fact, the mandibular ramus length in OPG–/– mice with bisphosphonate was similar to the length in WT mice without bisphosphonate. Histologically, the surface irregularity of the mandibular condyle that was observed in the OPG–/– mice without bisphosphonate tended to be less marked in the OPG–/– mice with bisphosphonate, and the proportion of the area of the cartilage layer relative to the whole condyle was significantly larger in OPG–/– mice with bisphosphonate than in those without bisphosphonate. In conclusion, bisphosphonate treatment results in an increase in mandibular condylar dimensions and normalization of mandibular ramus growth.     

Distinct and Overlapping Patterns of Localization of Bone Morphogenetic Protein (BMP) Family Members and a BMP Type II Receptor During Fracture Healing in Rats

Bone morphogenetic proteins (BMPs) and their receptors (BMPRs) are thought to play an important role in bone morphogenesis. The purpose of this study was to determine the locations of BMP-2/-4, osteogenic protein-1 (OP-1, also termed BMP-7), and BMP type II receptor (BMPR-II) during rat fracture healing by immunostaining, and thereby elucidate the possible roles of the BMPs and BMPR-II in intramembranous ossification and endochondral ossification. In the early stage of fracture repair, the expression of BMP-2/-4 and OP-1 was strongly induced in the thickened periosteum near the fracture ends, and coincided with an enhanced expression of BMPR-II. On day 7 after fracture, staining for BMP-2/-4 and OP-1 immunostaining was increased in various types of chondrocytes, and was strong in fibroblast-like spindle cells and proliferating chondrocytes in endochondral bone. On day 14 after fracture, staining with OP-1 antibody disappeared in proliferating and mature chondrocytes, while BMP-2/-4 staining continued in various types of chondrocytes until the late stage. In the newly formed trabecular bone, BMP-2/-4 and OP-1 were present at various levels. BMPR-II was actively expressed in both intramembranous ossification and endochondral ossification. Additionally, immunostaining for BMP-2/-4 and OP-1 was observed in multinucleated osteoclast-like cells on the newly formed trabecular bone, along with BMPR-II. In reference to our previous study of BMP type I receptors (BMPR-IA and BMPR-IB), BMPR-II was found to be co-localized with BMPR-IA and BMPR-IB. BMP-2/-4 and OP-1 antibodies exhibited distinct and overlapping immunostaining patterns during fracture repair. OP-1 may act predominantly in the initial phase of endochondral ossification, while BMP-2/-4 acts throughout this process. Thus, these findings suggested that BMPs acting through their BMP receptors may play major roles in modulating the sequential events leading to bone formation.     

Bone lengthening osteogenesis,a combination of intramembranous and endochondral ossification: an experimental study in sheep

We evaluated the morphological features of the newly formed tissue in an experimental model of tibial callotasis lengthening on 24 lambs, aged from 2 to 3 months at the time of operation. A unilateral external fixator prototype Monotube Triax^® (Stryker Howmedica Osteonics, New Jersey) was applied to the left tibia. A percutaneous osteotomy was performed in a minimally traumatic manner using a chisel. Lengthening was started 7 days after surgery and was continued to 30 mm. The 24 animals were randomly divided into three groups of 8 animals each: in Group 1, lengthening took place at a rate of 1 mm/day for 30 days; in Group 2, at a rate of 2 mm/day for 15 days; in Group 3, at a rate of 3 mm/day for 10 days. In each group, 4 animals were killed 2 weeks after end of lengthening, and the other 4 animals at 4 weeks after end of lengthening. To assess bony formation in the distraction area, radiographs were taken every 2 weeks from the day of surgery. To study the process of vascularization, we used Spalteholz’s technique. After killing, the tibia of each animal was harvested, and sections were stained with hematoxylin and eosin, Masson’s trichrome, and Safranin-O. Immunohistochemistry was performed, using specific antibodies to detect collagens I and II, S100 protein, and fibronectin. A combination of intramembranous and endochondral ossification occurred together at the site of distraction. Our study provides a detailed structural characterization of the newly formed tissue in an experimental model of tibial lengthening in sheep and may be useful for further investigations on callotasis.     

The Effect of Prior Bisphosphonate Exposure on the Treatment Response to Teriparatide in Clinical Practice

Our objective was to determine the effect of prior bisphosphonate exposure on the treatment response to teriparatide. All patients started on teriparatide in our hospital are entered into a database. All patients who had at least 12 months’ treatment were identified. Patients were divided into two groups depending on whether or not they had prior bisphosphonate exposure, and the response to teriparatide was compared using procollagen of type 1 N-terminal propeptide (P1NP) and bone mineral density (BMD). Fifty-two patients had been treated for at least 12 months, 38 with prior bisphosphonate exposure and 14 without. The mean duration of bisphosphonate treatment was 67 months, discontinued a mean of 1 month previously. P1NP increased significantly at 3 and 6 months in both groups. However, those without previous bisphosphonate treatment had a higher baseline P1NP (49 vs. 30 μg/L, P < 0.01), and this remained higher at 3 months (109 vs. 71 μg/L, P = 0.10) and 6 months (183 vs. 126 μg/L, P = 0.06), although the difference was not significant. In the prior bisphosphonate and bisphosphonate naive groups, respectively, the change in spinal BMD was 9.0% and 7.8% (P = 0.54) at 12 months and 9.8% and 6.1% (P = 0.30) at 18 months. The respective change in hip BMD was 1.0% and −0.3% (P = 0.36) at 12 months and 2.8% and 1.3% (P = 0.44) at 18 months. There was a trend toward a smaller but still significant increase in P1NP in response to teriparatide in bisphosphonate-treated patients. Although this suggests a blunting of the anabolic effects, in our clinic population this did not result in a reduction in BMD gain.     

Localization of Pigment Epithelium-Derived Factor in Growing Mouse Bone

Pigment epithelium-derived factor (PEDF) is a potent anti-angiogenic factor found in a wide range of fetal and adult tissues, where it is thought to play a role in the regulation of angiogenesis during development. The temporal expression of PEDF during endochondral bone formation has not previously been reported. In this study, we analysed the expression pattern of PEDF in growing mouse hindlimbs from newborn day one through to maturation at week 9, using immunohistochemistry and in situ hybridization. PEDF expression was demonstrated in chondrocytes within the resting, proliferative and upper hypertrophic zones of the epiphyseal growth plate. The pattern of expression was consistent throughout the developmental stages of the mouse. In addition, PEDF was expressed by osteoblasts lining the bone spicules in the ossification zone of metaphyseal bone, as well as by osteoblasts lining cortical periosteum. These novel results demonstrate that PEDF is developmentally expressed in both cartilage and bone cells during endochondral bone formation, and strongly suggest that it may play a regulatory role in the processes of chondrocyte and osteoblast differentiation, endochondral ossification, and bone remodelling during growth and development of long bones.     

Alkaline Phosphatases in Endochondral Ossification of Rats Low in Calcium and Vitamin D Deficient

Young rats fed a low calcium and vitamin D deficient diet for 2 weeks developed hypocalcemia and increased alkaline phosphatase activity in serum. The serum alkaline phosphatase activity (pNPPase) was found to be of skeletal origin. In accordance, the total non-specific alkaline phosphatase (pNNPase) activity in the microsomal fraction of tibial epiphyseal cartilage and metaphysis increased in the deficiently fed group when compared to the normal group. An increased activity in the microsomal fraction of tibial epiphyseal cartilage and metaphysis was shown both for inorganic pyrophosphatase and total ATP-degrading enzyme activity in the deficient group. This was also found in the presence of R 8231, indicating an increased activity of Ca²⁺-ATPase, shown to be present in both the epiphyseal plate and the metaphysis. These increased enzyme activities were consistent with the known effects of hypocalcemia and/or parathyroid hormone (PTH) on bone alkaline phosphatase activity. The increase in Ca²⁺-ATPase might, however, be a direct response to the hypocalcemia present in the deficient animals. Furthermore, the findings in the present study support the view that the same alkaline phosphatase iso-enzyme is present at different calcification loci.     

四种载体吸附自体骨髓细胞移植成骨作用的实验研究

目的　比较骨基质海绵 ,羟基磷灰石 ,明胶海绵及海螵蛸结合自体骨髓细胞在兔肌肉中的成骨作用。方法　应用骨基质海绵 ,羟基磷灰石 ,明胶海绵及海螵蛸结合自体骨髓细胞经过孵育后 ,植入兔股部肌肉内 ,分别于不同时间通过X线及组织学观察 ,计算机图像分析 ,评价各不同组织的成骨情况。结果　 12周时 ,骨基质海绵组成骨能力最强 ,羟基磷灰石组次之 ,海螵蛸组成骨能力最弱 ,明胶海绵组无成骨能力。结论　骨基质海绵吸附自体骨髓是修复骨折及骨缺损的较好材料。     

The Efficacy of Bone Morphogenetic Protein‐2 Depends on Its Mode of Delivery

Bone morphogenetic protein‐2 (BMP‐2) induces bone regeneration in a dose‐dependent manner, with higher doses of BMP‐2 inducing greater bone formation. Previously, we showed that long‐term delivery of BMP‐2 provides better ectopic bone formation than short‐term delivery of an equivalent dose. In the present study, we investigated the efficacy of orthotopic bone formation over a range of BMP‐2 doses, using different delivery modes. Heparin‐conjugated poly(lactic‐co‐glycolic acid) nanospheres suspended in fibrin gel were used as a long‐term delivery system, and fibrin gel was used as a short‐term delivery system. Different doses of BMP‐2 were delivered to mouse calvarial defects using either long‐term or short‐term delivery systems. Eight weeks after treatment, bone regeneration was evaluated by histomorphometry. For both delivery systems, bone regeneration increased as the BMP‐2 dose increased up to 1 µg and did not increase beyond this dose. Importantly, at BMP‐2 doses higher than 1 µg, long‐term delivery resulted in much greater bone formation than short‐term delivery. This study shows that long‐term delivery of BMP‐2 is more effective at enhancing orthotopic bone formation than short‐term delivery over a range of doses.     

BMP-2基因转染对人成纤维细胞生长和增殖的影响

目的：研究人骨形态发生蛋白-2(BMP-2)基因转染对人成纤维细胞株KMB-17生长及增殖的影响。方法：将hBMP-2基因导入KMB-17细胞，检测其表达情况及对KMB-17细胞生长和增殖的影响。结果：KMB-17细胞至少可以表达BMP-2基因3周左右；并且增殖指数上升，细胞增殖加剧。结论：人成纤维细胞株KMB-17可以作为靶细胞用于BMP-2基因疗法研究。     

Geranylgeranylacetone Inhibits Formation and Function of Human Osteoclasts and Prevents Bone Loss in Tail-Suspended Rats and Ovariectomized Rats

Vitamin K is used for protecting against osteoporosis. Recently, it has been reported that the inhibitory effect of vitamin K₂ (menatetrenone) on bone resorption may be related to its side chain. Geranylgeranylacetone (GGA), known as teprenone, an antiulcer drug, has almost the same chemical structure as that of the side chain of menatetrenone. We hypothesized that GGA also has an inhibitory effect on osteoclastogenesis both in vitro and in vivo. GGA in pharmacological concentrations directly inhibited osteoclastogenesis from human monocytes induced by soluble receptor activator of nuclear factor-κB ligand. In addition, GGA induced degradation of actin rings in mature osteoclasts, which was reversed by adding geranylgeranylpyrophosphatase. Moreover, GGA increased the bone mineral density of total femur, proximal metaphysis, and diaphysis of femur in ovariectomized rats. GGA also prevented bone loss induced by hindlimb unloading in tail-suspended rats. These results indicate that GGA prevents bone loss by maintaining a positive balance of bone turnover through suppression of both the formation and the activity of osteoclasts. Thus, GGA could be used to prevent and improve osteoporosis.     

骨形态形成蛋白复合纤维蛋白载体修复全厚关节软骨缺损的实验研究

目的：用骨形态形成蛋白（BMP）复合纤维蛋白载体修复创伤性全厚关节软骨缺损,方法：60只新西兰家兔,体重2．5－3kg,雌雄不限,随机分为5组,每侧股骨髌髁关节面低速电钻钻一直径为4mm全厚关节软骨缺损,一侧缺损填充BMP／FS,对照侧缺损填充单纯FS,单纯BMP和空白组,膝关节不做固定,允许笼中自由活动,术后2,4,8,12周空气栓塞分批处死动物,大体观,组织学切片HE染色,S－100蛋白免疫组化染色和透射电镜观察实验结果,结果：术后4周,BMP／HF填充的部分关节软骨缺损由类透明软骨修复,术后8周,实验组缺损大部分由类透明软骨修复,而对照组则由纤维软骨或纤维组织修复,术后12周,实验组修复组织主要是透明软骨或类透明软骨,修复面较平整光滑,与周围组织愈合良好,但部分修复软骨面变薄,纤维化。结论：BMP／FS复合物促进了关节软骨的早期修复,并且最终的修复组织更接受正常的关节软骨,但术后12周修复的关节软骨出现退行性改变。     

Evaluation of Activity of Epiphyseal Plates in Growing Males and Females

To investigate the age-related activity of the epiphyseal plates, a retrospective study of ^99mTc-methylene diphosphonate bone scans was undertaken. The study comprised 81 males and 46 females aged 2 weeks to 24 years. The total percentage (%) whole-body (ratio of total physis activity to whole-body activity) and the regional % whole-body (ratio of physis activity of one region to whole-body activity) were derived. The ratio of physis activity of one region to the total physis activity was defined as % physis. Before age 12, total physis activity was found to contribute about 10% to whole-body activity. All total and regional % whole-body activities followed sigmoid curves with age. The differences of the parameters (transition centers and widths) suggested that there might be a later and longer period for the disappearance of physis activity in males than in females. For all the regions, % physis changed little with age until after puberty. At age <1, the proportion of bone activity in the body was about 30–35% for skull, 20–25% for lower limbs, and 5–15% for the rest of the regions. The maximal changes during growth occurred in the skull and the lower limbs. The age-related changes of physis activity during growth reflect a combination of the potential of bone to grow and the processes of bone growth and bone turnover. Bone scintigraphy is useful in understanding the changes of physis activity during growth.     

Stimulation of Bone Formation by Recombinant Fibroblast Growth Factor-2 in Callotasis Bone Lengthening of Rabbits

Bone lengthening by callotasis is one of the most useful methods not only for the treatment of short extremities but also for extensive bone defects; however, the procedure takes a long time especially for the consolidation of the distracted callus. In this study, effects of a single local injection of recombinant human fibroblast growth factor-2 (FGF-2 or basic FGF) on callotasis bone lengthening were examined in rabbits. Ten days after the osteotomy at the middle of the tibia and the installment of an external fixator, the osteotomized site was distracted at a rate of 1.4 mm/day for 7 days, resulting in 9.8 mm lengthening. On the final day of distraction, 200 μg of FGF-2 in 150 μl of saline solution or vehicle alone was injected into the center of the distracted callus. Injection of FGF-2 increased bone formation at the distracted callus radiologically and histologically. A significant effect on bone mineral content (BMC) at the callus was observed as early as 2 weeks, and FGF-2 increased the BMC about twofold at 5 weeks after a normal remodeling process. We conclude that the callotasis method in combination with FGF-2 injection at the consolidation step could be clinically beneficial to shorten the bone lengthening period. Received: 6 May 1997 / Accepted: 1 November 1998     

纤维蛋白凝胶复合骨形态发生蛋白和庆大霉素缓释药物治疗感染性骨缺损的实验研究

目的 探讨将纤维蛋白凝胶(FG)作为骨形态发生蛋白(BMP)及庆大霉素的共同载体,一期治疗感染性骨缺损。方法 48只青紫兰兔,制作慢性骨髓炎模型,清创后造成胫骨干骺端内侧1.5 cm长半环形骨缺损,采用三种方法进行处理:A组,植入FG、BMP和庆大霉素复合物;B组植入FG/BMP复合物;C组作为空白对照。术后观察动物一般情况,作骨细菌培养及其计数,X线摄片及组织学检查。结果 A组感染控制及骨修复均良好,感染控制率、再生骨量明显优于B组;B、C两组在感染控制率上无显著差异;C组动物骨修复差。结论 FG、BMP及庆大霉素复合物具有抗感染及促进成骨的双重作用,可用于感染性骨缺损的治疗,也可用于污染严重的开放性损伤造成的骨缺损的治疗,方法简便、易行。     

Effect of Zoledronate on Bone Quality in the Treatment of Aseptic Loosening of Hip Arthroplasty in the Dog

Periprosthetic bone loss, which is a direct cause of aseptic loosening in total hip arthroplasty (THA), can be suppressed by bisphosphonates. It is unknown how the quality of this bone is affected in the presence of both wear debris (from implant) and bisphosphonates. The objective of this study was to evaluate the effect of zoledronate (ZLN) on bone quality in the presence of wear debris [polyethylene (PE) particles] in a canine model of uncemented THA. Thirty dogs underwent THA, and aseptic loosening was induced via implantation of PE particles packed into the femoral component. For 26 weeks until sacrifice, two groups (each n = 10) received weekly injections of ZLN (low dose 2 μg/kg, high dose 10 μg/kg) and the third group (control) received saline. Histological and radiographic examinations were performed to evaluate the degree of implant reaction. Histomorphometry (static/dynamic) was performed to evaluate bone turnover. Back-scattered electron imaging was used to quantify the newly formed bone and to evaluate the mineralization distribution. Density fractionation and X-ray diffraction were used to evaluate mineral properties, while four-point bending was used to determine mechanical properties. A dose-dependent presence of newly formed subperiosteal bone was found, which appeared to be less mineralized than the adjacent cortical bone. The high-dose ZLN group showed decreased cortical porosity and turnover and increased mineralization profile, failure strength, and modulus. We conclude that ZLN affects some of the material properties of cortical bone and allows the newly formed subperiosteal bone to remain and therefore affect the overall quality of the bone.     

Sequential Treatment with Intermittent Low-Dose Human Parathyroid Hormone (1-34) and Bisphosphonate Enhances Large-Size Skeletal Reconstruction by Vascularized Bone Transplantation

Vascularized bone transplantation enables reconstruction of large skeletal defects, but this process needs a long time. Since short-term intermittent parathyroid hormone (PTH) enhances rat fracture healing, we investigated the effects of 4-week intermittent low-dose (10 μg/kg/day) or high-dose (100 μg/kg/day) PTH followed by 4-week vehicle, low-dose or high-dose intermittent PTH, or zoledronic acid (ZOL, 2 μg/kg/week), a potent bisphosphonate, on large skeletal reconstruction by vascularized tibial grafting in rats. Compared to 8-week vehicle, 8-week low-dose PTH did not significantly increase the serum osteocalcin level as well as the urinary deoxypyridinoline level, while 4-week low-dose or high-dose PTH followed by 4-week ZOL decreased both of these levels. Eight-week PTH increased the bone mass of the graft and strength of the reconstructed skeleton in a dose-dependent manner; notably, the reconstructed skeleton showed an obviously higher response to PTH compared to the contralateral nonoperated femur. In contrast, 4-week PTH followed by 4-week vehicle reduced these effects and caused local bone loss at the host-graft junctions. Four-week PTH followed by 4-week ZOL did not induce such bone loss; however, 4-week high-dose PTH followed by 4-week ZOL caused a large callus in the distal cortical junction. Four-week PTH followed by 4-week ZOL increased the bone mass and strength similarly to 8-week PTH. These preliminary findings suggest, for the first time, that sequential treatment with short-term intermittent low-dose PTH and bisphosphonate as well as long-term intermittent low-dose PTH treatment enhance large skeletal reconstruction by vascularized bone transplantation, though early timing of sequential antiresorptive treatment could result in delay of bone repair.     

复合骨形态发生蛋白胎儿骨修复长骨缺损的实验研究

寻找满意的骨形态发生蛋白（ＢＭＰ）的载体一直是应用ＢＭＰ修复骨缺损研究中的一个重要课题，为探讨胎儿骨（ＦＢ）能否成为ＢＭＰ载体，制备了复合ＢＭＰ胎儿骨（ＢＭＰ／ＦＢ），将其植入兔桡骨中段１５ｍｍ人工缺损处，以单纯ＦＢ植入、异体骨（ＡＬＢ）植入、空白作为对照，通过Ｘ线摄片，光镜观察，电子探针钙磷元素测定等方法了解各组骨缺损修复速度和愈合程度。结果发现ＢＭＰ／ＦＢ植入侧４周时骨缺损处有大量间充质细胞聚集，８周形成骨小梁，ＦＢ基本被吸收，１２周出现部分板层骨，钙磷值达到正常桡骨皮质骨水平，１６周骨细胞成熟，髓腔再通，外观塑形较好，在不同时间点骨缺损修复程度，ＢＭＰ／ＦＢ组明显优于ＦＢ组，ＦＢ组优于ＡＬＢ组，空白组骨缺损则被纤维组织，脂肪组织等填充。实验证明ＦＢ是一种良好的ＢＭＰ载体。     

Exercise and Mechanical Loading Increase Periosteal Bone Formation and Whole Bone Strength in C57BL/6J Mice but Not in C3H/Hej Mice

To identify the genes, and the mechanisms that account for the 53% higher peak bone density in C3H/HeJ (C3H) mice compared with C57BL/6J (B6) mice, we are performing quantitative trait locus and phenotypic analyses. The phenotypic studies revealed differences in bone formation and resorption, and showed that hindlimb immobilization (by sciatic neurectomy) caused a greater increase in endosteal resorption in the tibiae of B6 compared with C3H mice. The current studies were intended to examine the hypothesis that the bones of C3H mice are less sensitive to mechanical loading than the bones of B6 mice. To increase mechanical loading, 9-week-old female B6 and C3H mice (n = 10–13 mice/group) were subjected to a jumping exercise (20 jumps/day, 5 days/week, to heights of 20–30 cm) for a total of 4 weeks. Control mice did not jump. Osteocalcin, alkaline phosphatase (ALP) activity, and IGF-I were measured in serum. The left tibiae were used for histomorphometry (ground cross-sections prepared at the tibio-fibular junction) and the right tibiae and femora were used for determinations of bone breaking strength (3-point bending). The results of these studies revealed (1) significant effects of both mouse strain (B6 and C3H) and the jumping exercise on tibial strength; (2) an exercise-dependent increase in serum IGF-I in C3H, but not B6 mice; and (3) no effects on serum ALP or osteocalcin. The histomorphometric analyses showed no effect of exercise on C3H tibiae, but significant exercise-dependent increases in total bone area, periosteal perimeter, periosteal mineral apposition rate (MAR), and periosteal bone formation (P < 0.02 for each) in B6 tibiae. There were no effects of exercise on periosteal resorption or any endosteal measurement in either C3H or B6 mice. Since the jumping exercise was designed to cause a two–three fold increase in muscular-skeletal loading at the tibio-fibular junction, and the calculated stress (g/mm²) at this sampling site was only 16% greater for B6 compared with C3H mice, we had anticipated that both strains of mice would show exercise-dependent increases in periosteal bone formation, with a greater response in the B6 mice. The lack of a response in the C3H tibiae demonstrates that the bones of C3H mice are less sensitive to mechanical loading (and unloading) than the bones of B6 mice. Received: 21 July 1999 / Accepted: 2 November 1999     

Stimulation of Bone Formation In Vivo by Insulin-Like Growth Factor-II in Rats

Insulin-like growth factor-II (IGF-II) plays an important role in skeletal remodeling, however, little is known about its effect on bone formation in vivo. In our study of the stimulation of bone formation in vivo by IGF II we injected recombinant human IGF-II into the parietal bones of neonatal rats once a day for 12 days. The bone mineral density measured by dual energy X-ray absorptiometry and the thickness of IGF-II-injected parietal bones increased in a dose-dependent manner. The layers of osteoblasts were observed along the IGF-II-injected side. Received: 12 June 1997 / Accepted: 8 January 1998