Biomedical subjects

Y Takakura

Publications and source records attributed to Y Takakura.

At least 55 records · Page 3Linked to original sources

PubMed2001

In vivo recognition of mannosylated proteins by hepatic mannose receptors and mannan-binding protein.

In vivo recognition of mannosylated proteins by hepatic mannose receptors and serum mannan-binding protein (MBP) was investigated in mice. After intravenous administration, all three different (111)In-mannosylated proteins were taken up mainly by liver, and uptake was saturated with increasing doses. (111)In-Man-superoxide dismutases and (111)In-Man(12)- and (111)In-Man(16)-BSA had simple dose-dependent pharmacokinetic profiles, whereas other derivatives ((111)In-Man(25)-, -Man(35)-, and -Man(46)-BSA and (111)In-Man-IgGs) showed slow hepatic uptake at <1 mg/kg. Purified MBP experiments in vitro indicated that these derivatives bind to MBP in serum after injection, which interferes with their hepatic uptake. To quantitatively evaluate these recognition properties in vivo, a pharmacokinetic model-based analysis was performed for (111)In-Man-BSAs, estimating some parameters, including the Michaelis-Menten constant of the hepatic uptake and the dissociation constant of MBP, which correlate to the affinity of Man-BSAs for mannose receptors and MBP, respectively. The dissociation constant of Man-BSA and MBP decreased dramatically with increasing density of mannose, but the Michaelis-Menten constant of hepatic uptake of Man-BSA was not so sensitive to the change in density. This suggests that the in vivo recognition of MBP has a stronger cluster effect than that of mannose receptors. Differences obtained here are due to the unique arrangement of carbohydrate recognition domains on each mannose-specific lectin available for mannosylated ligand recognition.

Animals↗

PubMed2001

Transport characteristics of ebastine and its metabolites across human intestinal epithelial Caco-2 cell monolayers.

The transport characteristics of a selective peripheral H1 receptor antagonist, ebastine, a substrate for cytochrome P450 3A4, and its three major metabolites, i.e., the hydroxy metabolite of ebastine (M-OH), the pharmacologically active metabolite carebastine (Car), and the desbutyrophenone metabolite (des-BP), were studied in cultured human intestinal Caco-2 cells expressing a drug efflux pump, P-glycoprotein (P-gp), on the apical membrane. The polarized transport of [3H]cyclosporin A (CyA), mediated by P-gp in the basolateral to apical direction across the Caco-2 cell monolayers, was affected by the presence of ebastine in a concentration-dependent manner and significant inhibition was observed at high concentrations (>50 microM). M-OH (300 microM) also significantly inhibited whereas Car and des-BP did not. Although no marked polarized transport of [14C]ebastine in a secretory direction was observed in the Caco-2 systems, the flux in the basolateral to apical direction was slightly higher than that in the opposite direction at concentrations less than 30 microm. [14C]Ebastine (2 microM) uptake from the apical side was significantly increased in the presence of an excess of cold CyA, suggesting that the efflux process mediated by P-gp may be involved in the ebastine uptake by Caco-2 cells. Collectively, these results indicate that ebastine (and presumably M-OH) is transported via P-gp in Caco-2 cells, however, the affinity for P-gp is very low. It is unlikely that the secretory transport of ebastine mediated by P-gp will dramatically affect overall intestinal absorption in vivo because efficient passive diffusion of this drug should occur due to its high lipophilicity. However, it may be advantageous for its efficient first-pass metabolism.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2001

[Beta 3-adrenergic receptor agonists--past, present and future].

beta 3-Adrenergic receptors (beta 3-AR) play an important role in the thermogenesis in brown adipose tissue and lipolysis in white adipose tissue. beta 3-AR agonists developed in the early stages produced marked weight reduction and an anti-diabetic effect in rats and mice, but did not in humans, because of the difference in the chemical structure of the beta 3-AR. In 1995, a naturally occurring variant (Trp64Arg) of the human beta 3-AR gene was shown to be correlated with obesity and insulin resistance in Pima Indians. Moreover, the fact that white adipocytes produce various hormones and cytokines that cause life-style-related disease was recently made clear. Because the reduction of the visceral fat is thought to be important to prevent these diseases, the expectations for the human beta 3-AR agonist having a novel anti-obesity effect are rising. Some interesting findings were recently reported with beta 3-AR agonists: the difference of the lipolysis was dependent on the existence of the Trp64Arg mutation and the up-regulation effect of the UCP1 and beta 3-ARs themselves in the adipose tissue and skeletal muscle. Therefore, we introduce informations (past, present and future) on beta 3-AR agonists in this paper.

Adrenergic beta-Agonists↗

PubMed2001

Relationship between meniscal degeneration and element contents.

The purpose of this study is to investigate the relationship between meniscal degeneration and element contents. The contents of elements (calcium, phosphorus, sulfur, and magnesium) in the menisci from 17 patients with osteoarthritis (OA) of the knee, 6 with rheumatoid arthritis (RA), and 2 who underwent the surgical operation for malignant tumors (control) were analyzed by inductively coupled plasma-atomic emission spectrometry, and the menisci were divided into four stages (Stage 0-3) of histological degeneration. The calcium contents of the menisci were 0.26 +/- 0.16 in Stage 0, 0.50 +/- 0.37 in Stage 1, and 0.69 +/- 0.66 in Stage 2, respectively (the values represent mg elements/g dry tissue). They increased with the progression of the stage. This tendency was found in the menisci with OA, but was not clear in those with RA. The calcium content in the control group was 0.17 +/- 0.09 mg/g. There was no significant relationship between the stage of degeneration and the contents of phosphorus, sulfur, or magnesium. The calcium content of the meniscus might indicate the degree of meniscal degeneration.

Adolescent↗

PubMed2001

Age-related changes of bone mineral density in human calcaneus, talus, and scaphoid bone.

To examine whether the bone mineral density (BMD) decreases uniformly with aging in any spongy bones, the authors investigated age-related changes of BMD in the calcaneus, talus, and scaphoid bone. After the ordinary dissection by medical students was finished, calcanei, tali, and scaphoid bones were resected from the subjects, and BMDs were measured by dual-energy X-ray absorptiometry. Their BMDs seemed to decrease gradually with aging in the calcanei, tali, and scaphoid bones. It was found that there were statistically significant relationships between age and BMD in the men's and women's scaphoid bones, women's tali, and women's calcanei, but not in the men's tali and calcanei. It should be noted that there were significant relationships between age and BMD in both men's and women's scaphoid bones. In regard to relationship in BMD between the bones of the upper and lower limbs in individuals, it was found that the relationship between the calcaneus and talus was higher than that between the calcaneus and scaphoid bone. This suggests that there is a higher relationship in BMD between the two tarsal bones compared with that between the tarsal and carpal bones.

Aged↗

PubMed2001

Pharmacokinetic analysis of lectin-dependent biodistribution of fucosylated bovine serum albumin: a possible carrier for Kupffer cells.

To examine the potential utility of fucosylation of drug carriers for targeted drug delivery to Kupffer cells, the pharmacokinetics of (111)In-labeled fucosylated bovine serum albumin (Fuc-BSA) with different numbers of fucose residues (11, 16, 25, 31 or 41) was studied. After intravenous injection in mice, all (111)In-Fuc-BSAs were mainly delivered to the liver and their hepatic uptake became saturated when the dose was increased. Of these derivatives, only (111)In-Fuc41-BSA showed a slow plasma elimination at low doses, suggesting an interaction with blood components. Examination of binding conditions as well as electrophoretic analysis of the binding components indicated that the serum-type mannan binding protein (MBP) is responsible. Kupffer cells, which possess fucose receptors, showed the highest uptake of (111)In-Fuc41-BSA, followed by endothelial cells and hepatocytes. The hepatic uptake of (111)In-Fuc41-BSA was inhibited by co-injection of Gal42-BSA, but not by Man46-BSA. On the other hand, excess Fuc41-BSA inhibited the hepatic uptake of (111)In-Man46-BSA, while (111)In-Gal42-BSA did not: These findings suggest that not only the fucose receptors on Kupffer cells but also other lectins are involved in the biodistribution of Fuc-BSAs. To understand how the degree of fucose modification affects the binding affinity of Fuc-BSA with hepatic lectins and serum MBP, a pharmacokinetic analysis was performed based on a physiological model. The Michaelis constant of the hepatic uptake of (111)In-Fuc-BSA decreased with an increasing number of fucose units, and the intrinsic hepatic clearance of (111)In-Fuc25-, (111)In-Fuc31- and (111)In-Fuc41-BSAs was close to, or much greater than, the hepatic plasma flow rate, indicating efficient hepatic uptake of these derivatives. These results suggest that fucosylation is a potentially useful method making drug carriers selective for Kupffer cells, although extensive modification might result in retarded delivery due to binding to other lectins like MBP.

Animals↗

PubMed2001

[The relationship between beta 3-adrenoceptor and regulation of body fat mass, and food intake].

beta 3-adrenoceptor(beta 3-AR) plays important roles in thermogenesis of brown adipose tissue(BAT) and lypolysis of white adipose tissue(WAT). Anti-obesity effect of beta 3-agonists is reported, and the Trp64Arg point mutation of the human beta 3-AR gene is associated with abdominal obesity. beta 3-agonist decreases food intake in rat and mice, and its effect is confirmed by both direct infusions to the brain and peripheral injections. Stimulated thermogenesis of BAT increases glucose utilization, then 'glucose dip' signals meal initiation. Risen core temperature leads to meal termination. But, because of decreased ability for thermogenesis, meal size increases in many obese animal models. Further investigations are being carried out to make these problems clear.

Adipose Tissue↗

PubMed2001

Hepatic uptake and gene expression mechanisms following intravenous administration of plasmid DNA by conventional and hydrodynamics-based procedures.

Hepatic uptake and gene expression mechanisms following intravenous administration of naked plasmid DNA (pDNA) by conventional and hydrodynamics-based procedures were studied in mice. After conventional (normal) intravenous injection, (32)P-labeled pDNA was rapidly eliminated from the circulation and predominantly taken up by the liver nonparenchymal cells while no significant gene expression was observed in this organ. The hepatic uptake process was saturable. Involvement of a specific mechanism was demonstrated since the hepatic uptake of [(32)P]pDNA was dramatically inhibited by cold pDNA, calf thymus DNA, and some polyanions [polyinosinic acid (poly I), dextran sulfate], but not by others (polycytidylic acid, chondroitin sulfate). The liver endothelial cells appeared to be a major contributor because gadolinium chloride (GdCl(3))-induced Kupffer cell blockade did not affect the hepatic uptake. After intravenous injection of naked pDNA with a large volume of saline at a high velocity (hydrodynamics-based procedure), the apparent hepatic uptake profile was similar to that after normal injection. The hepatic uptake was not inhibited by prior administration of polyanions, including poly I, dextran sulfate, and heparin. The hydrodynamics-based procedure resulted in marked gene expression in the liver, which was not inhibited by prior administration of polyanions or GdCl(3) treatment. These results indicate that pDNA uptake is a nonspecific process. This hypothesis was supported by the finding that significant hepatic uptake of bovine serum albumin and immunoglobulin G was observed after the hydrodynamics-based procedure.

Animals↗

PubMed2001

Prevention of neutrophil-mediated hepatic ischemia/reperfusion injury by superoxide dismutase and catalase derivatives.

Our previous study demonstrated that the combination of mannosylated superoxide dismutase (Man-SOD) and succinylated catalase (Suc-CAT), both of which are designed to be targeted to liver nonparenchymal cells, is a promising approach to prevent the initial phase of hepatic ischemia/reperfusion injury induced by occlusion of the portal vein for 30 min followed by a 1-h reperfusion in mice. In this study, the preventive effects of these agents were examined on late-phase injury mediated by infiltrating neutrophils, a more severe condition than the initial one. Administration of Suc-CAT alone or with Man-SOD to mice undergoing hepatic ischemia/reperfusion significantly suppressed the expression of intercellular adhesion molecule-1 along the hepatic sinusoid and prevented neutrophil infiltration in the liver. Man-SOD and Suc-CAT also prevented the increase in plasma glutamic pyruvic transaminase and glutamic oxaloacetic transaminase activities after reperfusion lasting 3 and 6 h. Histological evaluation of liver tissues confirmed the efficacy of this treatment, suggesting that these SOD and catalase derivatives have the ability to suppress neutrophil-induced hepatic injury. These results demonstrate that targeted delivery of antioxidant enzymes to liver nonparenchymal cells is a promising approach to reducing the reactive oxygen species produced by Kupffer cells and neutrophils infiltrating into the tissue. Since Suc-CAT is partially taken up by hepatocytes via a catalase-specific uptake mechanism, such a fraction could also be involved in its preventive effect against the injury.

Alanine Transaminase↗

PubMed2000

The 4F2hc/LAT1 complex transports L-DOPA across the blood-brain barrier.

L-DOPA is transported across the blood-brain barrier (BBB) by an amino acid transporter, system L. Recently, it has been demonstrated that system L consists of two subunits, 4F2hc and either LAT1 or LAT2. 4F2hc/LAT1 and 4F2hc/LAT2 show different transport characteristics, while their distribution in the brain has not been determined. To clarify whether 4F2hc/LAT1 participates in L-DOPA transport across the BBB, we first examined the expression of 4F2hc/LAT1 in the mouse brain capillary endothelial cell line, MBEC4, as an in vitro BBB model. Northern hybridization and immunoblotting revealed that both 4F2hc and LAT1 are expressed and form a heterodimer in MBEC4 cells. To confirm whether 4F2hc/LAT1 acts as system L to transport L-DOPA, we characterized L-DOPA uptake into the cells. The uptake process was time-dependent, temperature-sensitive, and Na(+)-independent. Neutral amino acids with bulky side chains and a bicyclic amino acid, 2-aminobicyclo-[2, 2,1]-heptane-2-carboxylic acid (BCH), inhibited L-DOPA uptake into MBEC4 cells to a great extent, while an acidic amino acid, basic amino acids, and glycine had no effect. Other neutral amino acids, such as alanine, asparagine, glutamine, serine, and threonine inhibited L-DOPA uptake by 40-70% at most. These characteristics are more compatible with those of 4F2hc/LAT1, rather than those of 4F2hc/LAT2. Finally, immunohistochemistry with anti-LAT1 antibody demonstrated that LAT1 is predominantly expressed in the microvessels of the central nervous system. This is the first report showing that the 4F2hc/LAT1 complex participates in L-DOPA transport across the BBB.

Amino Acid Transport Systems↗

PubMed2000

Effect of DNA/liposome mixing ratio on the physicochemical characteristics, cellular uptake and intracellular trafficking of plasmid DNA/cationic liposome complexes and subsequent gene expression.

In order to identify the important factors involved in cationic liposome-mediated gene transfer, in vitro transfection efficiencies by plasmid DNA complexed with DOTMA/DOPE liposomes at different DNA/liposome mixing ratios were evaluated using four types of cultured cells with respect to their physicochemical properties. Significant changes were observed in the particle size and zeta potential of the complexes as well as in their structures, assessed by atomic force microscopy, which depended on the mixing ratio. In transfection experiments, except for RAW 264.7 cells (mouse macrophages), efficient gene expression was obtained in MBT-2 cells (mouse bladder tumor), NLH3T3 cells (mouse fibroblasts) and HUVEC (human umbilical vein endothelial cells) at an optimal ratio of 1:5, 1:7.5 or 1:5, respectively. On the other hand, cellular uptake of the [32P]DNA/liposome complexes increased in all cell types with an increase in the mixing ratio, which was not reflected by the transfection efficiency. The cellular damage determined by MTT assay was minimal even at the highest DNA/liposome ratio (1:10), indicating that the lower gene expression level at the higher ratio was not due to cytotoxicity induced by the complex. An ethidium bromide intercalation assay showed that the release of plasmid DNA from the complex, following the addition of negatively charged liposomes, was restricted as the mixing ratio increased. Furthermore, confocal microscopic studies using HUVEC showed that the 1:5 complexes exhibited a dispersed distribution in the cytoplasm whereas a punctuate intracellular distribution was observed for the 1:10 complexes. This suggests that there was a significant difference in intracellular trafficking, probably release from the endosomes or lysosomes, of the plasmid DNA/cationic liposome complexes between these mixing ratios. Taken together, these findings suggest that the DNA/liposome mixing ratio significantly affects the intracellular trafficking of plasmid DNA complexed with the cationic liposomes, which is an important determinant of the optimal mixing ratio in cationic liposome-mediated transfection.

Animals↗

PubMed2000

Morphologic changes of the ankle in children as assessed by radiography and arthrography.

Chronological changes in the morphology of the ankle, a joint that consists primarily of chondral components in children, were investigated by arthrography and plain radiography. Arthrography was performed in 57 ankles of 40 patients with normal ankles (aged from 2 months to 3 years, 4 months; mean, 1 year, 7 months), and plain radiography was performed on 183 joints of 126 patients with normal ankles (aged from 3 years, 6 months to 14 years, 5 months (mean, 7 years, 8 months). The angle of the distal tibial joint surface was then measured on each radiograph. Despite being evident at birth, valgus inclination in the ankle rapidly changed during the first and second years of life. Thereafter, change continued gradually and spontaneously, and the ankles were in the neutral position by 3 years of age. However, the morphology of the ankles did not change much after that time. Normal ankles show valgus inclination at birth, but this configuration is changed naturally over time, and the ankles are in the neutral or slightly varus position by the age of bone maturity.

Adolescent↗

PubMed2000

Collateral sprouting mechanism after end-to-side nerve repair in the rat.

The collateral sprouting mechanisms of axons from an uninjured donor nerve after end-to-side nerve repair was investigated in motor nerves of rats, with special reference to the neurotrophins related to nerve regeneration. In addition, growth cone formation at the tip of the regenerating nerve was examined. A transected medial gastrocnemius nerve (MGN) was transferred to the side of an intact lateral gastrocnemius nerve (LGN) using a Y-shaped silicone tube. At 3, 7, or 14 days later, the MGN with the LGN was transected and was stained immunohistologically. Expression of neurotrophin-3 (NT-3) and Trk C (receptor of NT-3) was most significantly observed 3 days postoperatively around the site of coaptation. Brain-derived neurotrophic factor (BDNF) and Trk B (receptor of BDNF) was weakly detected at the coaptation site 3 days after-operation. Growth-associated protein 43 (GAP-43), which is a marker of growth cone formation, was observed at the site of coaptation in the LGN 7 days postoperatively and in the MGN at the site of coaptation at 14 days. We concluded that motor nerve regeneration due to collateral sprouting of axons after end-to-side nerve repair is possible. We thus demonstrated the involvement of at least one neurotrophin, NT-3, in the process of collateral sprouting of motor nerves.

Animals↗

PubMed2000

Flower-predominant expression of a gene encoding a novel class I chitinase in rice (Oryza sativa L.).

A flower-predominant cDNA for a gene, termed OsChia 1;175, was isolated from a cDNA library of rice pistils. Northern blot and RT-PCR analyses revealed that the OsChia 1;175 gene is highly expressed in floral organs (pistils, stamens and lodicules at the heading stage) but not or at an extremely low level in vegetative organs. OsChia 1;175 encodes a protein that consists of 340 amino acid residues, and the putative mature protein shows 52% to 63% amino acid identity to class I chitinases of rice or other plants. The phylogenetic tree shows that the OsChia 1;175 protein is a new type of plant class I chitinase in rice. The expression of OsChia 1;175 in vegetative organs is not induced by several chemicals, UV, and wounding. The soluble putative mature OsChia 1;175 protein expressed in Escherichia coli exhibited chitinase activity in the assay with colloidal chitin as a substrate. Genomic Southern analysis revealed that the OsChia 1;175 gene was organized as a low-copy gene family. The rice genomic library was screened and a genome clone corresponding to OsChia 1;175 was isolated. The transcription start sites of the OsChia 1;175 gene were mapped by primer extension analysis. The 1.2 kb putative promoter region of the OsChia 1;175 gene was fused to the GUS (beta-glucuronidase) gene, and this chimeric gene was introduced to rice by Agrobacterium-mediated transformation. The flower-predominant gene expression was identified also in the transgenic rice plants. The high promoter activity was detected in the stigmas, styles, stamens and lodicules in transgenic plants. The possible functions of OsChia 1;175 are discussed.

Amino Acid Sequence↗

PubMed2000

Hepatocyte-targeted in vivo gene expression by intravenous injection of plasmid DNA complexed with synthetic multi-functional gene delivery system.

To achieve hepatocyte-targeted in vivo gene expression, a carrier that controls both the tissue and intracellular distribution of DNA was designed and synthesized. A cationic polymer, poly(L-ornithine) (pOrn), was modified first with galactose, then with a fusigenic peptide (mHA2) to obtain Gal-pOrn-mHA2. When applied with Gal-pOrn-mHA2 to asialoglycoprotein receptor-positive cells, fluorescein-labeled DNA showed a diffuse profile, suggesting the release of DNA from endosomes and/or lysosomes by the carrier. Then the biodistribution and gene expression after intravenous injection of DNA complexes (10 microg DNA per mouse) were examined. After injection of [32P]DNA/Gal-pOrn-mHA2, about 60% of the radioactivity was recovered in the liver, mostly in parenchymal cells. A large amount (81 ng/g tissue) of transgene product (luciferase) was detected in the liver of mice injected with DNA/Gal-pOm-mHA2, which was 280-fold greater than that obtained with DNA/DOTMA:Chol liposomes (50 microg DNA). Prior administration of galactosylated albumin reduced the gene expression to 1/100, indicating the asialoglycoprotein receptor-mediated gene transfer in liver parenchymal cells, ie hepatocytes. The luciferase activity in hepatocytes contributed more than 95% of the total activity in all the tissues examined. Thus, hepatocyte-targeted in vivo gene expression was achieved by the intravenous injection of DNA complex with the multifunctional gene carrier.

Animals↗

PubMed2000

Intratumoral pharmacokinetics of oligonucleotides in a tissue-isolated tumor perfusion system.

The intratumoral pharmacokinetics of model oligonucleotides were studied in Walker 256 tissue-isolated tumor preparations using an in situ single-pass vascular perfusion technique. A 20-mer phosphodiester (PO) oligonucleotide, its fully phosphorothioated (PS) oligonucleotide counterpart, and an 18-mer phosphorothioated oligonucleotide containing four 2'-O-methylribonucleosides at both the 3'-end and 5'-end (PS-OMe) were used. These oligonucleotides were administered to the tumor in two ways, by constant arterial infusion and by direct intratumoral injection. In the case of constant arterial infusion, the experiments were carried out using perfusate with or without 4.7% bovine serum albumin (BSA). The protein binding of PO, PS, and PS-OMe to BSA was 46%, 87%, and 94%, respectively. No marked difference was observed between the degree of accumulation of the three types of oligonucleotides in the tumor when BSA was present in the perfusate. PS and PS-OMe showed higher degrees of accumulation in tumors compared with PO when no BSA was present. These results indicate that free (i.e., protein unbound) PS-OMe and PS have superior tumor accumulation characteristics. In the intratumoral injection experiments, PS-OMe was retained longer in tumor tissue compared with PS, suggesting that it might be useful for direct local injection into solid tumors. Thus, the present study provides useful information about the basic disposition characteristics of oligonucleotides in solid tumors.

Animals↗

PubMed2000

Integral method to study transition radiation from surfaces with arbitrary profile

Transition radiation is produced when an electron moving at constant speed crosses the boundary separating two media with different optical properties. We propose an alternative description of this phenomenon, based on an integral representation of the electromagnetic field and show that the approach gives known results for a flat surface. Compared to previously published methods, based either on the reciprocity theorem in electromagnetism or on a four-dimensional Fourier representation of the field generated by the moving electron, this method has the advantage that it can be applied to general boundary geometries.

Journal Article↗

PubMed2000

Follow-up study of MRI for osteochondral lesion of the talus.

Characteristic MRI findings of osteochondral lesions of the talus have been reported. We examined how they change before and after treatment and discussed their significance. Twenty two ankles in 21 patients had MRI examination before and after treatment of the talar lesion. We evaluated the changes in the low intensity areas in T1-weighted image and the signal rims behind osteochondral fragment in T2-weighted image which have been reported as characteristic findings. Clinical symptoms were improved postoperatively in all subjects. The low intensity areas in T1-weighted image seen before the surgical treatment tended to decrease in size postoperatively. The low intensity area in T1-weighted image was reduced in 15 of the 22 ankles (68.2%). Low signal rim in T2-weighted image was seen in three cases before the treatment. All disappeared completely after arthroscopic drilling. Similarly, high signal rim in T2-weighted image seen in 13 cases before the treatment disappeared in 10 postoperatively. These findings were considered indicative that surgical treatments reduced abnormal stress of the underlying bone element due to unstable osteochondral fragment, leading to reduction of the low intensity area. The disappearance of signal rims in T2-weighted images was considered to indicate obliteration of the interface between the osteochondral fragment and the talar bed with bone union. We believe that MRI of the osteochondral lesion of the talus will be useful for postoperative evaluation allowing assessment of the need for further treatment. The decreasing size of low intensity areas in T1-weighted images and disappearance of signal rims behind the osteochondral fragment in T2-weighted images suggested healing of the osteochondral lesions.

Adolescent↗