Biomedical subjects

J I Ahn

Publications and source records attributed to J I Ahn.

9 recordsLinked to original sources

PubMed2001

Effect of N-glycosylation on ligand binding affinity of rat V1a vasopressin receptor.

A rat Vla vasopressin (rVla) receptor has two putative N-glycosylation sites at 14th and 27th amino acid asparagine in the extracellular N-terminus. In the present study, we examined the possible roles of N-glycosylation of the N-terminus in the receptor function. Three point mutants for deglycosylated rVla receptor were generated in which the 14th and/or the 27th asparagine was replaced with glutamine, namely N14Q, N27Q, and N14:27Q, each tagged with an enhanced green fluorescent protein (EGFP) at their C-termini, and transfected to COS-7 or HEK292 cells. The two single mutants and a double mutant have progressively smaller molecular mass compared to the wild-type receptor as determined by immunoblot analysis, indicating that the two sites are effectively glycosylated in vivo. The maximal ligand binding capacities of three mutant receptors were comparable to that of wild-type (17.02 +/- 1.32 pmol/g protein) with modest changes in ligand binding affinities: N27Q and N14:27Q had decreased binding affinities compared to N14Q and wild-type receptors. The reduced binding affinities of the deglycosylated mutants are not likely due to the impaired intracellular transport since their traffickings were indistinguishable from one another. Taken together, these results suggest that the N-glycosylation at the two sites of the N-terminus of rV1a receptor minimally affects the surface expression and trafficking of the receptor.

Animals↗

PubMed1995

The effect of chondroitinase ABC on rabbit intervertebral disc. Radiological, histological and electron microscopic findings.

Seventy-eight rabbit lumbar discs were evaluated by radiographs and histology after the injection of chondroitinase ABC (40 U/ml for each disc) and compared with injection with phosphate buffer, and also with a control group who were not injected. There was considerable narrowing of the disc space after chondroitinase ABC injection. Safranin-0 depletion was present in the anterior part of the annulus fibrosus near to the nucleus pulposus in all the treated discs, indicating loss of proteoglycan. Electron microscopy showed collapse of the chondrocytes and notochordal cells. These findings suggest that chondroitinase ABC may be another chemonucleolytic agent which decreases disc volume and consequently decompresses the spinal cord or nerve roots; its effects were confined to the tissues within the intervertebral disc.

Animals↗

PubMed1994

Pathological fractures secondary to unicameral bone cysts.

We carried out a retrospective review of 75 children with unicameral bone cysts, who had sustained 52 pathological fractures, to determine which cysts were likely to be at risk and whether healing was accelerated after a fracture. Most lesions were in the metaphysis of a tubular bone, the commonest sites being the the upper part of the humerus and femur. The percentage of bone occupied by the cyst in the transverse plane was more than 85% in both anteroposterior and lateral radiographs in every case of pathological fracture. In most cases, the cyst recurred and sometimes became large without any acceleration of healing.

Adolescent↗

PubMed1994

Chondrocyte allograft transplantation for damaged growth plate reconstruction.

The growth plate is responsible for longitudinal bone growth. The problem of repair of damaged growth plate in children has never been adequately solved. The purpose of this study is to investigate the ability of the cultured chondrocyte for the prevention of bony bridge and repairment of damaged growth plate. Chondrocytes were obtained from the new born canine epiphyseal plate and was cultured in high density. Fourteen days later they formed micromass easily removable from the culture flask. Twenty dogs were divided into two groups; in group I, the medial proximal tibial growth plate was destroyed and then cultured chondrocytes were transplanted into the defect, and in group II, the medial proximal tibial growth plate was left in destroyed state. Each left leg was remained as a control. The growth pattern was observed radiographically and histologically until 16 weeks after graft. 4 weeks after the operation, the angular deformity had been observed, and 31 degrees of angulation was noted at the 16th week in group II, while there was less than 8 degrees of angulation and nearly normal growth in most of dogs of group I (8 of 10 dogs). The other 2 dogs had shown 20 degrees angulation. In group II, there was definite bony bridge on the medical proximal growth plate. In group I, initially, the cultured chondrocyte remained as a amorphous cartilagenous mass, but as time progressed, amorphous cartilagenous mass had formed cartilagenous matrix which was proved by Safranin-O staining. Although this study showed the role of cultured chondrocyte as a method of preventation of bony bridge formation and possibility to repair of growth plate, further studies should be done to prove the reconstruction of the growth plate.

Animals↗

PubMed1993

Intraosseous ganglion. Report of a case.

We report a case of an intraosseous ganglion of the lateral malleolus of the ankle. The lesion was accompanied by a cystic bursa overlying the lateral malleolus. There were connections between the ankle joint, the intraosseous ganglion, and the overlying cyst. Radiographs of the lesion showed the cystic defect in the lateral malleolus surrounded by a sclerotic rim, suggesting that the lesion had progressed very slowly.

Ankle↗

PubMed1991

Cementless total hip arthroplasty with PCA prosthesis.

Eighty-one cases of cementless porous-coated total hip arthroplasties in 74 patients were analyzed. Hip rating scores as described by Harris were used, and AP and lateral radiographs were made serially: preoperatively, 3 months, 6 months, 1 year, and 2 years postoperatively. The average postoperative hip rating score was 91 points (range: 76 to 100 points) at 1 year and 93 points (range: 74 to 100 points) at 2 years. The overall clinical results were satisfactory in these patients at both 2 and 4 years. However, slight to mild thigh pain was observed in 16 (19.8%) of 81 hips at 2 years, and 10 (21.3%) of 47 hips at 4 years postoperatively. Moderate to severe limp was seen in 11 (13.6%) of 81 hips at 2 years and seven (14.9%) of 47 hips at 4 years postoperatively.

Adult↗

PubMed1991

Bilateral fracture-dislocation of the sacroiliac joint: a case report.

Bilateral fracture-dislocation of the sacroiliac joint with intrapelvic displacement of the sacrum is a rare and extremely severe injury. We treated a patient with bilateral fracture-dislocation of the sacroiliac joint using a nonoperative method and obtained an excellent functional result.

Adult↗

PubMed1990

Cerebrotendinous xanthomatosis.

A case report on a 23-year-old female patient with cerebrotendinous xanthomatosis (CTX) is presented. From 8 years of age, the patient clinically showed multiple xanthoma masses on both knees, both heels, and the nasal bridge, juvenile cataracts, multiple abnormal neurologic dysfunctions, and dementia. The level of cholestanol in urine, serum, and xanthoma mass tissues was increased, as determined by capillary gas chromatography.

Adult↗

PubMedDate not supplied

Congenital absence of the lung.

Four cases of congenital absence/aplasia of the lung associated with congenital vertebral anomalies are reported. Although alteration in arterial blood gas determinations and vital capacities occurred, the patients tolerated general anesthesia well.

Abnormalities, Multiple↗