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S T Jeong

Publications and source records attributed to S T Jeong.

15 recordsLinked to original sources
PubMed2001

Crystallization and preliminary X-ray analysis of a thermoalkalophilic lipase from Bacillus stearothermophilus L1.

A thermoalkalophilic lipase from Bacillus stearothermophilus L1 (L1 lipase) was crystallized in two different crystal forms using a low concentration of the enzyme and a calcium-exchange process. The first, needle-like, crystal form, which diffracts to about 3.5 A, belongs to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 67.84, b = 72.96, c = 104.41 A. The second, monoclinic, crystal form, which behaves better than the first form for crystallographic analyses, belongs to the monoclinic space group C2 and has unit-cell parameters a = 119.62, b = 85.05, c = 98.36 A, beta = 99.73 degrees. From the monoclinic crystals, a native data set and a samarium-derivative data set were collected to 2.0 and 2.3 A resolution, respectively. The difference Patterson map between the two data sets shows strong heavy-atom peaks, indicating that the crystals are suitable for a high-resolution structure determination.

Crystallization↗
PubMed2001

Binding and regulation of HIF-1alpha by a subunit of the proteasome complex, PSMA7.

The hypoxia-inducible factor-1alpha (HIF-1alpha) is an important transcription factor for cellular responses to oxygen tension. It is rapidly degraded under normoxic conditions by the ubiquitin-dependent proteasome pathway. Here we report a critical role of the 20S proteasome subunit PSMA7 in HIF-1alpha regulation. PSMA7 was found to interact specifically with two subdomains of HIF-1alpha. PSMA7 inhibited the transactivation function of HIF-1alpha under both normoxic and hypoxia-mimicking conditions. In addition, we show that the PSMA7-mediated regulation of HIF-1alpha activity is associated with the proteasome pathway.

Binding Sites↗
PubMed2001

Iliacus hematoma and femoral nerve palsy after revision hip arthroplasty: a case report.

Femoral nerve palsy occurred in a 65-year-old man after he had undergone a revision total hip arthroplasty using cementless components. The magnetic resonance imaging scan showed a mass in the iliacus muscle. The mass showed increased signal intensity on T1-weighted and T2-weighted spin-echo images and contained linear septa and a nodule. The gadolinium-enhanced T1-weighted image showed a rim of significant enhancement in the nodule. The findings of magnetic resonance images were suggestive of iliacus hematoma and of liposarcoma. The patient underwent surgery, and the mass was identified as an iliacus hematoma. The femoral nerve was stretched by the hematoma. After removal of the hematoma, the nerve palsy was improved completely. Iliacus hematoma may occur after total hip arthroplasty, even without anticoagulant therapy. The hematoma might appear to be a liposarcoma on magnetic resonance imaging scans.

Aged↗
PubMed1999

Recombinant hemoglobin(alpha 29leucine --> phenylalanine, alpha 96valine --> tryptophan, beta 108asparagine --> lysine) exhibits low oxygen affinity and high cooperativity combined with resistance to autoxidation.

Using our hemoglobin expression system in Escherichia coli, we have constructed three recombinant hemoglobins (rHbs) with amino acid substitutions located in the alpha(1)beta(1) and alpha(1)beta(2) subunit interfaces and in the distal heme pocket of the alpha-chain: rHb(alphaV96W, betaN108K), rHb(alphaL29F, alphaV96W, betaN108K), and rHb(alphaL29F). rHb(alphaV96W, betaN108K) exhibits low oxygen affinity and high cooperativity and also ease of autoxidation of the heme iron atoms from the Fe2+ state to the Fe3+ state. It has been reported by Olson and co-workers [Carver et al., (1992) J. Biol. Chem. 267, 14443-14450; Brantley et al. (1993) J. Biol. Chem. 268, 6995-7010] that a mutation at position 29 (B10, helix notation), e.g. , Leu --> Phe, can inhibit the autoxidation of the heme iron of myoglobin. We have introduced such a mutation into our rHb having low oxygen affinity and high cooperativity. This triply mutated rHb(alphaL29F, alphaV96W, betaN108K) is stabilized against autoxidation and azide-induced oxidation compared to the double mutant, rHb(alphaV96W, betaN108K), but still exhibits low oxygen affinity and good cooperativity. According to electron paramagnetic resonance results, the oxidized form of the triple mutant shows a high ratio of an anionic form of bishistidine hemichrome. Previous reports have suggested that this form does not have water present at the distal heme pocket. (1)H nuclear magnetic resonance spectra of the triple mutant in the ferric state also exhibit spectral features characteristic of hemichrome-type signals. We have carried out a series of biochemical measurements to characterize these three interesting rHbs and to compare them to human normal adult hemoglobin. These results provide new insights into the structure-function relationship of hemoglobin with amino acid substitutions in the alpha(1)beta(1) and alpha(1)beta(2) interfaces and in the heme pockets.

Amino Acid Substitution↗
PubMed1999

Bone marrow edema and associated pain in early stage osteonecrosis of the femoral head: prospective study with serial MR images.

PURPOSE: To determine whether the marrow edema around focal osteonecrosis on magnetic resonance (MR) images is associated with clinical symptoms. MATERIALS AND METHODS: Thirty-three patients with 37 hips showing early stage osteonecrosis of the femoral head were followed up at 3-month intervals with clinical evaluation, conventional radiography, and serial MR imaging. RESULTS: Seven (50%) of 14 symptomatic hips showed marrow edema around focal osteonecrosis on initial MR images, whereas only one (4%) of 23 asymptomatic hips showed edema (P < .01). Six (86%) of seven hips that were moderately to severely painful were associated with surrounding marrow edema. All eight hips showing osteonecrosis with marrow edema at the initial MR examination had joint effusion and exhibited intense radionuclide uptake in the proximal femur, which corresponded to the extent of edema on MR images. In all eight hips, the marrow edema resolved on follow-up MR images, and the pain subsided with the resolution of edema. CONCLUSION: The results of this study suggest that the combination of marrow edema of the proximal femur and focal osteonecrosis of the femoral head are strongly associated with hip pain in early stage osteonecrosis, even prior to collapse. Pain improvement usually parallels the resolution of edema.

Adolescent↗
PubMed1999

Borderline necrosis of the femoral head.

To determine whether the histologic lesions classified by the system of Arlet et al as Type 2 (granular necrosis of fatty marrow) and Type 3 (complete medullary and trabecular necrosis) always progress to Type 4 (complete necrosis with marginal medullary fibrosis and appositional new bone formation), 10 femoral heads (nine patients) were monitored for 4 years using serial magnetic resonance images. These femoral heads had been diagnosed histologically as having either Type 2 (seven hips) or Type 3 (three hips) necrosis on initial core biopsies. On the initial magnetic resonance image, none of the femoral heads showed any focal lesions indicative of osteonecrosis. In all instances, superselective angiography showed interruption of the superior retinacular artery, and the bone marrow pressure was elevated. During a followup period of 48 to 54 months, no patient had a reactive low signal intensity band develop on T1 weightings, as evidence of a reparative process around the necrotic portion of the lesion, or any other findings of osteonecrosis on magnetic resonance images. These findings suggest that some Type 2 and 3 lesions of Arlet et al may not develop an obvious reactive interface of reparative revascularization and thus may not progress to definite and classic Type 4 osteonecrosis. This study supports the hypothesis that there is an ischemic threshold between reversible intraosseous hypoxia (bone marrow edema syndrome) and irreversible intraosseous anoxia (classic bone infarction or osteonecrosis) and suggests that borderline necrosis occurs in the transition zone of this ischemic threshold and is nonprogressive.

Adult↗
PubMed1998

Tibial bone defects treated by internal bone transport using the Ilizarov method.

We reviewed 27 cases of tibial bone defects treated by internal bone transport using the Ilizarov method. The causes of the bone defects were open fractures in 14 segments and infected non-unions in 13. The average length of the defects was 8.3 cm (range, 3-20 cm). There were 21 one-level tibial transports, 3 two-level tibial transports, 1 one-level tibial transport with fibular transport, and 2 fibular transports. At the docking site, 25 segments underwent bone grafting. Eleven of the 25 were Papineau-type open cancellous bone grafts. Acute shortening or docking was performed in 10 segments. Bone union was obtained in every instance. The average time of external fixation was 8 months and the average time to union was 7.1 months. Bone grafting at the docking site is recommended in order to shorten the duration of treatment and to prevent refracture and non-union.

Adolescent↗
PubMed1997

Identification of the functional importance of valine-19 residue in streptokinase by N-terminal deletion and site-directed mutagenesis.

Streptokinase (SK) is a bacterial plasminogen activator of multi-domain structure. In deletion analysis of the N-terminal region of SK, the deletion of 20 amino acids (SK delta N20) resulted in the dramatic reduction of plasminogen activator activity compared to deletion of 7 (SK delta N7) and 13 amino acids (SK delta N13). The incubation time to reach maximal active site generation in an equimolar mixture of SK delta N20 and plasminogen was the same as that for wild-type SK. To identify the functional residues important in plasminogen activation, several site-directed mutations were introduced at the region spanning Ser16-Val20 of SK. The results showed that Val19 residue is important for the activity of the SK-plasminogen complex.

Amino Acid Sequence↗
PubMed1997

Supracondylar osteotomy with Ilizarov fixation for elbow deformities in adults.

Stable fixation after a corrective supracondylar osteotomy in adults is difficult because of the irregularity of the area of bony contact, displacement of the fragments, the predominance of cortical bone, and the need for early mobilisation. We have used the Ilizarov apparatus for fixation in 15 patients who were treated by complex osteotomies with displacement of fragments for cubitus varus or valgus. Most patients with cubitus varus required medial displacement with rotation of the distal fragment. Those with cubitus valgus required lateral shift of the distal fragment to reduce the medial prominence of the elbow that would otherwise result. All osteotomies united within the expected time without loss of correction, despite early mobilisation. Complications related to the fixation were few and had resolved at the long-term follow-up.

Adolescent↗
PubMed1997

Antibiotic-impregnated cement beads in the treatment of chronic osteomyelitis.

Fifty-four patients with chronic osteomyelitis of the long bones were treated at Gyeong-Sang National University Hospital between 1985 and 1993 using the cement bead technique. We studied the results of thirty-one patients who were followed up for 3 years or more. The average duration of follow-up was 4 years and 2 months (range: 3 to 7 years). All of the patients were treated by a two-stage operation; primary saucerization with implantation of antibiotic-impregnated polymethylmethacrylate beads and secondary bone grafts. The most recent follow-up examinations and analyses revealed that 17 patients (55%) were completely free of infection. Ten patients (32%) required repeated procedures of curettage and/or bone grafting. Amputations were performed on 4 patients.

Adolescent↗
PubMed1996

Decreased agglutinability of methoxy-polyethylene glycol attached red blood cells: significance as a blood substitute.

Human Rb(+) AB type red blood cells were modified with methoxy-polyethylene glycol (mPEG) in order to decrease agglutinabilities toward clinically important anti-A, anti-B and anti-D reagents. Attachment of mPEG to membrane proteins of the red blood cell was identified by the shift of well-known blood group active glycoprotein bands such as band 3, 4.5 and PAS-1 on the SDS-polyacrylamide gel electrophoresis. When 4mM concentration of mPEG was added to red blood cells, agglutination was minimum by a blood group typing and microwell agglutination tests. Antibody binding tests showed decreased antibody binding to blood group antigens after mPEG attachment. The decrease of both agglutinability and antibody binding was the result of mPEG attachment to blood group active glycoprotein of the cell membrane. The morphology of red blood cells after mPEG attachment was the usual discocytic cell. Oxygen equilibrium curves of the mPEG-attached red blood cells were similar to unmodified red blood cells. This approach to decrease agglutinability of the red blood cells toward blood group antibodies may be used to develop a universally transfusible blood substitute.

Blood Substitutes↗
PubMed1995

Preventing collapse in early osteonecrosis of the femoral head. A randomised clinical trial of core decompression.

We performed a randomised trial on 37 hips (33 patients) with early-stage osteonecrosis (ON). After the initial clinical evaluation, including plain radiography and MRI, 18 hips were randomly assigned to a core-decompression group and 19 to a conservatively-treated group. All the patients were regularly followed up by clinical evaluation, plain radiography and MRI at intervals of three months. Hip pain was relieved in nine out of ten initially symptomatic hips in the core-decompression group but persisted in three out of four initially painful hips in the conservatively-treated group at the second assessment (p < 0.05). At a minimum follow-up of 24 months, 14 of the 18 core-decompressed hips (78%) and 15 of the 19 non-operated hips (79%) developed collapse of the femoral head. By survival analysis, there was no significant difference in the time to collapse between the two groups (log-rank test p = 0.79). Core decompression may be effective tin symptomatic relief, but is of no greater value than conservative management in preventing collapse in early osteonecrosis of the femoral head.

Adolescent↗
PubMed1991

Molecular cloning and nucleotide sequence of Streptomyces griseus trypsin gene.

Streptomyces griseus trypsin (E.C. 3.4.21.4) is one of the major extracellular proteinase, which is secreted by S. griseus. The gene encoding S. griseus trypsin was isolated from a S. griseus genomic library by using a synthetic oligonucleotide probe. Fragments containing the gene for S. griseus trypsin were characterized by hybridization and demonstration of proteolytic activity in S. lividans. Deduced amino acid sequence from the nucleotide sequence suggests that S. griseus trypsin is produced as a precursor, consisting of three portions; an amino-terminal pre sequence (32 amino acid residues), a pro sequence (4 residues), and the mature trypsin. The S. griseus trypsin consists of 223 amino acids with a computed molecular weight of 23,112. The existence of proline at the pro and mature junction suggests that the processing of S. griseus trypsin is non-autocatalytic.

Amino Acid Sequence↗
PubMedDate not supplied

Comparison of MRI with subchondral fracture in the evaluation of extent of epiphyseal necrosis in the early stage of Legg-Calvé-Perthes disease.

We reviewed 20 patients in the early stage of Legg-Calvé-Perthes disease who showed a subchondral fracture line in radiographs. All 20 patients underwent magnetic resonance imaging (MRI) within 2 months after the first symptoms. Follow-up MRI after treatment was performed in 10 patients. The subchondral fracture line in radiographs and serial T1-weighted image was used to measure the extent of the epiphyseal necrosis volumetrically. These extents in the early stage were compared with those in the late stage for determination of prognostic significance. The intensities of coronal MRIs under the subchondral fracture were not homogeneous. The uninvolved epiphysis also showed nonhomogeneous intensities because the posterior column revealed higher intensity compared with the anterior column. The extent of the subchondral fracture line is more accurate in predicting the amount of eventual necrosis than is the extent of necrosis in MRI, which does not have a consistent correlation.

Child↗