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Biomedical subjects

Mitsuo Ochi

Publications and source records attributed to Mitsuo Ochi.

At least 127 records · Page 7Linked to original sources
PubMed2003

Drilling from the intercondylar area for treatment of osteochondritis dissecans of the knee joint.

We demonstrate a new method in which a drilling is made from the intercondylar space, and its efficacy in treating osteochondritis dissecans (OCD) of the knee in skeletally immature patients with relatively stable lesions with an intact articular surface, in cases where there was failure of initial non-operative management. The lesions of 16 knees of 12 patients with OCD of the femoral condyles failed to heal by conservative treatment for more than 3 months (average 5-6 months) and thereafter were arthroscopically treated with drilling from not the transarticular but the intercondylar bare area without damaging the articular surface. Eight lesions involved the medial femoral condyle, and eight involved the lateral femoral condyle. The average follow-up was 16 months. All lesions healed after drilling, and the average time of healing was 4 months by X-ray and 7 months by MRI. The average Lysholm score improved from an average of 70.4 points at preoperation to an average of 97.8 points after operation. The results of the Hughston Rating Scale were similar: 10 of the 12 patients showed excellent results and the remaining two patients good results. We advocate our new and less invasive procedure of drilling from the bare area of the intercondylar space for OCD in the knee joint of skeletally immature patients who have had failure of initial non-operative management.

Adolescent↗
PubMed2003

Effects of cell density on proliferation and matrix synthesis of chondrocytes embedded in atelocollagen gel.

The effects of cell density on the proliferation and chondroitin sulfate synthesis of chondrocytes embedded in Atelocollagen gel were examined. Chondrocytes of 21 10-week-old Japanese white rabbits isolated by collagenase digestion were embedded in Atelocollagen gel and cultured in Dulbecco's modified Eagles medium at cell densities of 2 x 105 cells/ml (105 group), 2 x 106 cells/ml (106 group), and 2 x 107 cells/ml (107 group) for 4 weeks. Chondrocytes in the 105 group gradually proliferated more than the other two groups. In contrast, most chondrocytes in the 107 group showed increased capability to produce chondroitin 6-sulfate. Cartilage-like tissue was produced from high-density cultures (107 cells/ml), although a decrease in cell number was seen. Even in three-dimensional cultures, the proliferation and chondroitin sulfate synthesis of chondrocytes were influenced by the cell density. These results are informative for the clinical application of chondrocyte transplantation in three-dimensional cultures for cartilage repair.

Animals↗
PubMed2003

Cryotherapy influences joint laxity and position sense of the healthy knee joint.

OBJECTIVE: To investigate the influences of cryotherapy on the anteroposterior (AP) laxity and the joint position sense of the knee. DESIGN: Experimental. SETTING: University hospital in Japan. PARTICIPANTS: Twenty healthy volunteers (10 men, 10 women; age range, 21-28y) were analyzed. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: A cooling pad was applied to the knee for 15 minutes under the circulating medium at 4 degrees C. The subject's skin temperature over the anteromedial aspect of the knee was measured during the 15 minutes of cooling and again 15 minutes later. The accuracy of the knee joint position sense was evaluated before and after cooling by using a modified Skinner's method. AP displacement and anterior terminal stiffness (ATS) of the knee were obtained with a KT-2000 trade mark knee arthrometer. RESULTS: Total (AP) laxity and anterior knee laxity decreased by 1.0 and 1.2mm after 15 minutes of cooling (P=.003, P=.017), respectively. ATS and inaccuracy of position sense increased by 21N/mm and 1.7 degrees (P<.001, P=.003), respectively. All parameters had normalized at 15 minutes postcooling. CONCLUSION: Cooling for 15 minutes makes the knee joint stiffer and lessens the sensitivity of the position sense. These findings may be significant and should be taken into account for therapeutic programs that involve exercise immediately after a period of cooling.

Adult↗
PubMed2003

Attachment of autogenous tendon graft to cortical bone is better than to cancellous bone: a mechanical and histological study of MCL reconstruction in rabbits.

We analyzed the mechanical and histological variables after the attachment of an autogenous tendon graft to cortical or cancellous bone. We reconstructed the medial collateral ligament of the knee in 33 Japanese white rabbits, using a bone socket procedure. The floor of the bone socket was cortical bone in group A and cancellous bone in group B. Mechanically, the pull-out test showed a tendency towards an increase in maximum failure load, with 10.9 N, 35 N and 37 N in group A, and 11 N, 18 N and 36 N in group B at 2, 4 (statistically significant difference) and 8 weeks after surgery, respectively. Histologically, the attachments were immature at 2 weeks. At 4 weeks, granulations had matured and Sharpey's fiber-like structures were seen. These fibers were more abundant in group A than in group B. At 8 weeks, the attachments in both groups were rather like the normal 4-zone structure. With time, tendon attachments matured in both groups. Our study showed that reattachment of tendons to cortical bone may be bettter than to cancellous bone.

Analysis of Variance↗
PubMed2003

Temporal changes in posterior laxity after isolated posterior cruciate ligament injury: 35 patients examined by stress radiography and MRI.

We examined the temporal changes in posterior laxity and MRI findings in acute isolated posterior cruciate ligament (PCL)-injured knees. 35 patients with acute isolated PCL injuries who attended our clinic within 10 weeks of an injury underwent nonoperative treatment, and were chronologically evaluated for posterior laxity and MRI. We divided them in 3 groups, as regards the evolution of laxity and MRI findings. In 20 patients, the degree of posterior laxity was slight throughout the observation periods. In 9 patients, who had severe posterior laxity on their initial visit, the laxity had improved markedly 6 months after injury and did not deteriorate. In 6 patients the severe posterior laxity did not improve during the study. 4 patients whose PCL on MRI was seen as a continuous swollen band having high signal intensity and showed consistently good stability or even an improvement. We conclude that acute isolated PCL injuries with a continuous swollen band on MRI should be treated conservatively for at least 6 months after injury, even if the posterior laxity is severe initially.

Adolescent↗
PubMed2003

Effects of neurotrophic factors on chemokinesis of Schwann cells in culture.

Schwann cells are support cells in the peripheral nervous system and are responsible for migration, adhesion, production of the extracellular matrix, and myelination. Migration is considered to be essential for nerve regeneration after transsection. We have examined the chemokinetic effects of nerve growth factor (NGF), brain derived growth factor (BDNF), and neurotrophin-3 (NT-3) on Schwann cells in vitro using a chemotaxis chamber. The chemokinetic activity of Schwann cells was strongly accelerated by NGF, but was not influenced by BDNF. NT-3 at a concentration of 1 ng/ml had a stimulatory effect on chemokinesis. These data suggest that NGF is a chemoattractant for Schwann cells in vitro. Giving exogenous NGF might stimulate both migration of Schwann cells and the formation of Büngner's bands after peripheral nerve injuries in animal models.

Animals↗
PubMed2003

Optimum combination of monolayer and three-dimensional cultures for cartilage-like tissue engineering.

The autologous chondrocyte transplantation technique has been introduced for the repair of articular cartilage defects. The advantage of transplanting chondrocytes cultured in suspension includes the in vitro expansion of cell numbers. However, the disadvantages include the potential leakage of cells from defects, dedifferentiation of cellular phenotype, and uneven distribution of cells. Transplantation of chondrocytes cultured in collagen gel resolves those problems. However, the expansion of cells in three-dimensional culture is more difficult than in monolayer culture, and for practical reasons only limited numbers of chondrocytes can be obtained from an unloaded area of the knee. To develop a method for the production of high-quality cultured grafts, we investigated the combination of monolayer culture for cell expansion and three-dimensional culture for maintenance of cell phenotype. Articular chondrocytes from rabbits were divided into four groups, exposed to various combinations of culture conditions, and cultured for a total of 3 weeks. Each group was evaluated histologically, biochemically, and biomechanically. Our findings showed that the combination of 2 weeks of monolayer culture followed by 1 week of three-dimensional culture resulted in the highest chondroitin sulfate levels, sufficient cell numbers, and adequate stiffness of the chondrocyte-collagen composites, giving optimal graft preparation.

Cartilage↗
PubMed2003

Articular cartilage restoration with costal cartilage previously fused with bone.

A novel procedure was developed for restoration of an articular cartilage defect using an autologous costal cartilage prepared with iliac bone, and the durability in vivo of this biologic construct was examined. First, an osteochondral complex was prepared (successful preparation, 67 of 80). Cancellous bone blocks isolated from the ilium of male Japanese White rabbits aged 5 months were implanted onto the surface of the costal cartilage before being tied by a pair of 3-0 silk thread sutures that were looped around the costal cartilage from behind. Second, 3 months later, the bone-attached costal cartilage was harvested and implanted into a full-thickness cartilage defect induced in a trochlear groove of the femur. All of the grafts were fixed to the recipient, maintaining its cartilage structure until 6 months (n = 28) and 12 months (n = 12) after implantation. However, when the costal cartilage without any bony portion was implanted into a similarly induced defect, 42% (10 of 24) were detached from the recipient before 12 months after implantation. The nontreated defect did not heal spontaneously to a satisfactory level (n = 12). These findings suggest that an osteochondral fragment, prepared by grafting cancellous bone onto costal cartilage, can be used for articular cartilage restoration.

Animals↗
PubMed2003

Targeted gene delivery to human osteosarcoma cells with magnetic cationic liposomes under a magnetic field.

Gene delivery using cationic liposomes results in relatively low transfection, especially under in vivo conditions. This system, however, can overcome some of the problems associated with viral delivery systems. The present study was carried out in order to improve the transfection efficiency of cationic liposomes by preparing magnetic cationic liposomes (MCL). Small MCL approximately 40 nm in diameter and incorporating one or two magnetite particles were prepared with phosphatidylethanolamine and 3beta-[N-(N', N'-dimethylaminoethane)-carbamoyl] cholesterol. The efficiency of MCL in gene delivery was evaluated by using plasmid DNA containing a luciferase reporter gene and human osteosarcoma Saos-2 cells. Without a magnetic field, maximum luciferase activity was observed when DNA was mixed with MCL at a 1:5 ratio and incubated with cells for 6 h. Under a magnetic field, maximum luciferase activity was achieved by 30-min magnetic induction. This improvement in transfection efficiency by magnetic induction was approximately 3.5-fold. The feasibility of this active transgenic system was further shown by measuring apoptosis rates after transfection of the p53 gene to Saos-2 cells. Apoptosis rates increased to 18.9% from 2.4% by magnetic induction. In conclusion, a gene delivery system including MCL and magnetic induction was found to achieve rapid and enhanced gene delivery in vitro. Such a gene delivery system may be applicable under in vivo conditions, and is expected to offer numerous clinical advantages.

Bone Neoplasms↗
PubMed2002

AG-041R, a cholecystokinin-B/gastrin receptor antagonist, stimulates the repair of osteochondral defect in rabbit model.

A newly synthesized compound (AG-041R), 3R-1-(2,2Diethoxyethyl)-((4methylphenyl) amino-carbonyl methyl)-3-((4methylphenyl) ureido-indoline-2-one), is a cholecystokinin-B/gastrin receptor antagonist which has stimulatory effects on the matrix synthesis of chondrocytes in vitro. In this study, we examined the effect of AG-041R on the repair of osteochondral defects (cylindrical, 4 mm diameter) in the patellar groove of the rabbit knee joint. At the time of operation, 100 microl of 1 microM of AG-041R was administered, followed by 200 microl with an osmotic pump for 14 days. Histological and biochemical evaluations were performed at 12 and 24 weeks after surgery. The histological score of the AG-041R-treated group, the quantity of glycosaminoglycan and the ratio of chondroitin sulfate in the AG-041R-treated tissue were significantly higher than in the untreated group. Moreover, the degeneration of cartilage around the defect was suppressed in the AG-041R-treated group. These findings suggest that AG-041R is effective for the repair of osteochondral defects.

Animals↗
PubMed2002

Spontaneous healing of acute anterior cruciate ligament (ACL) injuries - conservative treatment using an extension block soft brace without anterior stabilization.

To evaluate the spontaneous healing capability of acute anterior cruciate ligament (ACL) injuries, conservative treatment was applied in a selected group of 31 patients, who had low athletic demands. Each patient demonstrated a continuous ACL on magnetic resonance imaging (MRI), from the original femoral attachment through the tibial attachment, and an area of high intensity was detected in the substance of the ACL. The injured knees were treated using an extension block soft brace without anterior stabilization for 2-3 months. KT-2000 and MRI examinations were carried out regularly during the follow-up. Twenty-three knees (74%) were revealed to be stable in the follow-up examination, with an average of 16.1 months elapsing since the initial injuries. The KT-2000 side-to-side differences of 20 knees were less than 3 mm, and those of the other 3 knees were more than 3 mm but less than 5 mm. MRI confirmed that 21 injured ACL out of 23 knees maintained a femoral to tibial attachment and showed gradual reductions in image intensity. The positions of the other 2 injured ACL femoral attachments were different from the original femoral attachment: one was attached to the posterior cruciate ligament, and the other was located at the lateral femoral condyle anterior to the original femoral attachment. Eight knees (26%) subsequently required ACL reconstructions due to instability. This study indicates that an acutely injured ACL has healing capability. It also suggests that conservative management of the acute ACL injury can yield satisfactory results in a group of individuals who have low athletic demands and continuous ACL on MRI, provided the patients are willing to accept the slight risk of late ACL reconstruction and meniscal injury.

Adolescent↗
PubMed2002

Mechanical properties of newly developed loop ligament for connection between the EndoButton and hamstring tendons: comparison with Ethibond sutures and Endobutton tape.

A new artificial loop ligament (LL) without mechanical weak points, such as a knot, has been developed to connect the EndoButton and hamstring tendons for anterior or posterior cruciate ligament (CL) reconstruction. This study assessed the mechanical properties of the LL and sutures (No. 5 Ethibond thread, EndoButton tape) and those of the different CL constructs with these materials and fixation devices commonly used in CL reconstruction. The LL had a significantly higher ultimate tensile load (UTL) and stiffness value (p < 0.001) than No. 5 Ethibond thread or EndoButton tape in static and fatigue tests (50--500 N, 1.08 million cycles). The LL-tendons-Leeds-Keio artificial ligament-staple construct complex also had significantly higher UTL and stiffness value than the Ethibond loops or EndoButton tape loop-tendons-Ethibond sutures-postscrew-fixed construct complex. Furthermore, the LL construct complex elongated the least after cyclic loading (50--150 N, 90,000 cycles). These findings suggested that using the LL construct complex might avoid a bungee cord effect and elongation before biological healing between the construct and bony socket. The LL construct complex could be a safe substitute for use during the postoperative period.

Elasticity↗
PubMed2002

Anterior cruciate ligament injury in recreational alpine skiers: analysis of mechanisms and strategy for prevention.

Between 1995 and 1997, a retrospective survey was conducted in Japan to classify the types of injuries sustained by recreational alpine skiers. The purpose of this study was to investigate the causes and mechanisms of lower-extremity equipment-related (LEER) anterior cruciate ligament (ACL) injury in this population. Seventy-seven (96%) of the 80 respondents reported that their ski bindings did not release their ski boots at the time of their accident, and 30 respondents (38%) reported functional failure of their ski bindings, or that the ski boots came off. By presenting this investigation, we hope to give sports medicine clinicians a better understanding of LEER injuries and insights into how to prevent such injuries.

Adult↗
PubMed2002

Effects of different embedding gels on periostealchondrogenesis in vitro.

To develop a more useful organ culture model for periosteal chondrogenesis in vitro, we compared the effects of the embedding of explants in agarose versus collagen gels. Chondrogenic differentiation was examined by means of histological observation and in terms of the expression of mRNA encoding two cartilage markers, Type II collagen and Aggrecan. Periosteal explants were derived from the tibiae of rabbits. These explants were embedded in either agarose gel or collagen gel and cultured for 6 weeks. Histological examinations revealed that in the agarose gel, cells were neither present in the explants nor in the gel. In the collagen gel, cells migrated from the explanted tissues into the gel, and some cells were round. However, no explants showed safranin-O staining. Only 10% of 10 surviving explants in the agarose gel expressed the Type II collagen gene and the Aggrecan gene. On the other hand, of 25 surviving explants in the collagen gel, the expression of the Type II collagen gene was detected in 18 explants (72%) and that of the Aggrecan gene was detected in 21 explants (84%). In conclusion, we demonstrated that the periosteum exerts chondrogenesis in certain circumstances and its chondrogenesis is closely related to the culture material.

Aggrecans↗
PubMed2002

Vastus lateralis release for painful bipartite patella.

PURPOSE: The purpose of this study was to evaluate the efficacy of vastus lateralis release for painful bipartite patella. We have also compared the results of open method versus arthroscopic method using a holmium:YAG laser system (OmniPulse Holmium Laser System; Trimedyne Inc, Irvine, CA). TYPE OF STUDY: This study was a nonrandomized control and cross-over trial. METHODS: Fifteen patients with 17 painful bipartite patella who underwent vastus lateralis release were included in this study. The average age of patients was 14.3 +/- 2.2 years. In 7 knees of 6 patients, vastus lateralis release was performed through a skin incision over the bipartite fragment, and in 10 knees of 9 patients, we performed the procedure arthroscopically with the holmium:YAG laser. We assessed clinical and radiographic data of the patients chronologically in both groups. RESULTS: In all patients, pain over the fragment disappeared within 4 weeks after the operation, and all returned to their previous sports activities at an average of 3.1 +/- 0.9 months postoperatively. Clinical assessment was classified as excellent in 13 knees and good in 4 knees. Bone union at 6 months after the operation was complete in 11 knees (64.7%) and incomplete in 6 knees (35.3%), and none of the knees was graded as not healed. Bone union in patients with an age of 15 or younger was significantly better than that in patients over 15 years of age (P <.05). Release under arthroscopy showed statistically better results in duration of knee effusion (P <.05), return of circumference of thigh (P <.05), and return of muscle strength (P <.05). CONCLUSIONS: Because vastus lateralis release is less invasive surgery with good results, we conclude that this procedure can be a first choice of operative treatment for painful bipartite patella.

Adolescent↗
PubMed2002

Mechanoreceptors in the anterior cruciate ligament contribute to the joint position sense.

We have investigated the correlation between the number of mechanoreceptors in anterior cruciate ligament (ACL) remnants and the joint position sense just before an ACL reconstruction in 29 patients. The number of mechanoreceptors was evaluated histologically, using the Gairns gold chloride method. Mechanoreceptors were also found in patients who had a long interval between injury and the operation. A joint position sense test was done within 3 days before surgery. We found a positive correlation between the number of mechanoreceptors and accuracy of the joint position sense, suggesting that proprioceptive function of the ACL is related to the number of mechanoreceptors. Therefore, we should consider preserving ACL remnants during ACL reconstruction.

Adolescent↗