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Biomedical subjects

S K Rhee

Publications and source records attributed to S K Rhee.

54 records · Page 3Linked to original sources
PubMed1997

Varus and internal rotational deformity of the ankle secondary to distal tibial physeal injury.

Nine children who sustained Lauge-Hansen's supination-inversion injury of distal tibial physeal injury with intact distal fibular physis, were followed until their maturity. The average varus deformity was 39 degrees (maximum, 80 degrees) with 23 degrees of internal rotational deformity. The longitudinal growth of the fibula was retarded compared with opposite normal leg. There was early closure of the medial distal tibial physis, gradual upward migration of medial malleolus, and eventually medial subluxation of the ankle; these resulted in gradual varus and internal rotational deformities of the injured ankle. It is thought that the resultant disabling deformity of ankle should be prevented by any means, though presently there are no available effective methods of treatment. It is suggested that the repeated corrective osteotomy should be carried out before epiphyseal deformity of the distal tibia and subluxation of the ankle joint develop.

Ankle Joint↗
PubMed1997

Valgus ankle secondary to acquired fibular pseudoarthrosis in children. Long-term results of the Langenskiöld operation.

Nine cases of acquired absence of the fibular shaft were studied to determine the growth contribution of the distal fibula; in 6 cases the absence was caused by osteomyelitis and in 3 cases by trauma. The average valgus and external rotational deformities were 15.2 degrees and 10 degrees, respectively. In 3 of 7 cases surgically treated with Langenskiöld operation or supramalleolar corrective osteotomy, the valgus deformity recurred during the postoperative growth period. The speculated causes of gradual valgus deformity are the loss of physiologic thrust from the proximal to distal fibula, the tethering effect of contracted soft tissue on distal fibula and early physeal closure of the lateral part of the distal tibia due to continuous, uneven axial overloading. The Langenskiöld operation was found effective for the stability of ankle joint in the initial period, but could not prevent the postoperative revascularization of the ankle. However, it is strongly recommended that any types of prophylactic surgery should be carried out before the development of an epiphyseal deformity of distal tibia, and to prevent secondary osteoarthritis of the ankle joint.

Adolescent↗
PubMed1996

Channel-forming activity of immunoaffinity-purified connexin32 in single phospholipid membranes.

Connexin32, a member of the family of proteins that forms gap junction channels between cells, was immunoaffinity-purified from rat liver using a monoclonal antibody, under nondenaturing conditions and reconstituted into unilamellar phospholipid liposomes and bilayers. Gel-filtration studies indicate that the connexin32 is purified predominantly in structures of a size consistent with that of single hemichannels and too small to be junctional channels (dimers of hemichannels). Purified connexin formed channels permeable to sucrose and to Lucifer Yellow. The permeability was reversibly reduced by acidic pH and unaffected by several agents that modulate coupling between cells. Modeling of the distribution of the permeability in the liposomes indicates that it is mediated by connexin structures that distribute among the liposomes as single hemichannels. Bilayer recordings of the purified connexin show high conductance channels with asymmetric voltage sensitivity. The results show that immunopurified connexin32 can form channels, in single phospholipid membranes, that have permeability similar to that of gap junction channels and thus can be utilized in studies of permeability and its regulation to investigate its role in normal physiological function, development, and disease.

Animals↗
PubMed1996

Influence of a supplementary carbon source on biodegradation of pyridine by freely suspended and immobilized Pimelobacter sp..

The effect of the presence of supplementary glucose or acetate on the growth and pyridine-degrading activity of freely suspended and calcium-alginate-immobilized Pimelobacter sp. was investigated. Although the supplementary carbon sources could be degraded simultaneously with pyridine, Pimelobacter sp. exhibited a preference for pyridine over supplementary carbon sources. Thus, the pyridine-degrading activity of the freely suspended cells was not decreased significantly by the addition of either glucose (1.5-6 mM) or acetate (6-24 mM) to the pyridine (6-24 mM). In the semi-continuous immobilized cell culture, immobilized cells also exhibited a preference for pyridine over supplementary carbon sources and did not switch their substrate preference throughout the culture. Owing to a high cell concentration, the volumetric pyridine degradation rate at 24 mM pyridine in the immobilized cell culture was approximately six times higher than that in the freely suspended cell culture. Furthermore, the immobilized cells could be reused 16 times without losing their pyridine-degrading activity during the culture period tested. Taken together, the use of immobilized Pimelobacter sp. for the degradation of pyridine is quite feasible because of the preference for pyridine over supplementary carbon sources, the high volumetric pyridine degradation rate, and the reusability of immobilized cells.

Acetates↗
PubMed1996

A novel autonomously replicating sequence (ARS) for multiple integration in the yeast Hansenula polymorpha DL-1.

Several autonomously replicating sequences of Hansenula polymorpha DL-1 (HARSs) with the characteristics of tandem integration were cloned by an enrichment procedure and analyzed for their functional elements to elucidate the mechanism of multiple integration in tandem repeats. All plasmids harboring newly cloned HARSs showed a high frequency of transformation and were maintained episomally before stabilization. After stabilization, the transforming DNA was stably integrated into the chromosome. HARS36 was selected for its high efficiency of transformation and tendency for integration. Several tandemly repeated copies of the transforming plasmid containing HARS36 (pCE36) integrated into the vicinity of the chromosomal end. Bal 31 digestion of the total DNA from the integrants followed by Southern blotting generated progressive shortening of the hybridization signal, indicating the telomeric localization of the transforming plasmids on the chromosome. The minimum region of HARS36 required for its HARS activity was analyzed by deletion analyses. Three important regions, A, B, and C, for episomal replication and integration were detected. Analysis of the DNA sequences of regions A and B required for the episomal replication revealed that region A contained several AT-rich sequences that showed sequence homology with the ARS core consensus sequence of Saccharomyces cerevisiae. Region B contained two directly repeated sequences which were predicted to form a bent DNA structure. Deletion of the AT-rich core in region A resulted in a complete loss of ARS activity, and deletion of the repeated sequences in region B greatly reduced the stability of the transforming plasmid and resulted in retarded cell growth. Region C was required for the facilitated chromosomal integration of transforming plasmids.

Base Sequence↗
PubMed1996

A comparative study of the surgical procedures to treat advanced Kienböck's disease.

We have treated a total of 16 cases of advanced Kienböck's disease, stage III and IV by Lichtman's classification, with triscaphe fusion, tendon ball replacement arthroplasty after excision of lunate, proximal row carpectomy as a salvage procedure and limited wrist fusion, since 1985. All cases were followed for minimal 16 months after each operation. Tendon ball replacement arthroplasty after excision of lunate could not prevent further carpal collapse with persistent chronic wrist pain. The triscaphe fusion or radio-lunate fusion induced a marked limited wrist motion later, and the triscaphe fusion alone was not fit for the treatment of advanced one because of progressive proximal migration of capitate and continuous wrist pain due to ligamentous carpal instability in follow-up. So we tried to simultaneously combine tendon ball replacement arthroplasty after excision of lunate with triscaphe fusion in far advanced Kienböck's disease, and their end results was favorable. Proximal row carpectomy could be done in far advanced Kienböck's disease with reasonably painless wrist motions. The overall end results of proximal row carpectomy are much better than any form of carpal arthrodesis. Conclusively the proper way to treat advanced Kienböck's disease seems to depend on the patient's age, their job and sex, and the stage of disease. And the cause of wrist pain in advanced Kienböck's disease seems due to ligamentous carpal instability rather than osteoarthritis on radio-lunate joint.

Adult↗
PubMed1995

In vitro inhibition of gap junctional intercellular communication by chemical carcinogens.

This study was conducted to assess the effects of chemical carcinogens on the gap junction-mediated intercellular communication in cultured mammalian cells. The method of scrape-loading dye transfer of lucifer yellow was adapted as a measure of gap junctional communication. Clone 9 cells derived from rat liver were treated with a model chemical carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and the gap junctional communication was assessed by measuring the transfer of scrape-loaded lucifer yellow dye. When cells were treated with the carcinogen at 0.3 mg/ml, the fluorescent dye transfer was inhibited by 90% in 60 min. Other chemical agents, which include direct or indirect carcinogens and antitumor drugs, were also examined for their effects on the gap junctional communication. Direct carcinogens, such as MNNG, hydroxylamine and ethidium bromide, exhibited strong inhibition of intercellular communication, while indirect carcinogens, such as aflatoxin B1 and ethionine, exerted minor effects. Effects of test chemicals on the cell communication through gap junctions were readily quantitated by counting the number of cells stained with the fluorescent dye.

Animals↗
PubMed1995

A novel aerobic respiratory chain-linked NADH oxidase system in Zymomonas mobilis.

Membrane vesicles prepared from Zymomonas mobilis oxidized NADH exclusively, whereas deamino-NADH was little oxidized. In addition, the respiratory chain-linked NADH oxidase system exhibited only a single apparent Km value of approximately 66 microM for NADH. The NADH oxidase was highly sensitive to the respiratory chain inhibitor 2-heptyl-4-hydroxyquinoline-N-oxide. However, the NADH:quinone oxidoreductase was not sensitive to 2-heptyl-4-hydroxyquinoline-N-oxide and was highly resistant to another respiratory chain inhibitor, rotenone. Electron transfer from NADH to oxygen generated a proton electrochemical gradient (inside positive) in inside-out membrane vesicles. In contrast, electron transfer from NADH to ubiquinone-1 generated no electrochemical gradient. These findings indicate that Z. mobilis possesses only NADH:quinone oxidoreductase lacking the energy coupling site.

Aerobiosis↗
PubMed1994

Nucleotide and derived amino acid sequences of an extracellular sucrase gene (invB) of Zymomonas mobilis ZM1 (ATCC10988).

DNA sequence analysis of a previously cloned 4.5 kb DNA fragment showed that the extracellular sucrase gene (invB) of Zymomonas mobilis was located in the 155 bp downstream of levansucrase gene (levU). The invB gene had an open reading frame of 1242 bp and the deduced amino acid sequence was 413 residues with a molecular weight of 46,107. The translated sequence of Z. mobilis invB was in good agreement with the 10 N-terminal amino acid residues determined by amino acid sequencing. The amino acid sequence of sucrase showed low similarity with that of other sucrases, but higher similarity with that of levansucrases.

Amino Acid Sequence↗
PubMed1994

Cyclic AMP-dependent phosphorylation of an immunoaffinity-purified homotetrameric inositol 1,4,5-trisphosphate receptor (type I) increases Ca2+ flux in reconstituted lipid vesicles.

We established a novel method to isolate a single type of inositol 1,4,5-trisphosphate receptor (IP3R) among the heterogeneous population of receptors to study the regulatory mechanism of Ca2+ release. We raised in the rabbit a polyclonal antibody against synthetic peptide corresponding to amino acids 2736-2747 (pep 6) of type I IP3R (IP3-R-I) that is most abundant in cerebellum. We purified IP3R-I from a 1% 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid solubilized mouse cerebellar microsomal fraction by immunoaffinity chromatography on an anti-pep 6 antibody-Sepharose 4B column with specific elution by the pep 6 peptide (GHPPHMNVNPQQ) of the IP3R-I C terminus. Immunoaffinity-purified IP3R reconstituted into lipid vesicles formed a homotetramer structure. Monoclonal antibody 18A10, which partially blocks the Ca2+ release from cerebellar microsome, almost completely inhibited IP3-induced 45Ca2+ influx into proteoliposomes, whereas monoclonal antibody that recognizes other regions did not inhibit Ca2+ influx. Both the rate and extent of 45Ca2+ influx into proteoliposomes increased 20% after incubation with the catalytic subunit of cyclic AMP-dependent protein kinase, accompanied by stoichiometric phosphorylation of IP3R protein.

Amino Acid Sequence↗
PubMed1994

Optimization of the expression system using galactose-inducible promoter for the production of anticoagulant hirudin in Saccharomyces cerevisiae.

We have tried to optimize the galactose-inducible gene expression system for the overproduction of the potent thrombin-specific inhibitor, hirudin, in a genetically engineered yeast, Saccharomyces cerevisiae. The expression and secretion of hirudin were directed by the galactose-inducible promoter, GAL10, and the mating factor alpha pre-pro leader sequence. The initial hirudin expression level in shake-flask culture was 2.3 mg 1-1. Modification of the expression vector and optimization of culture conditions, including the induction conditions, improved the level of hirudin gene expression and secretion into the culture supernatant more than 20-fold (50 mg 1-1) in a 4-1 scale batch cultivation. The expression and secretion level of hirudin seemed to be partially dependent on cell growth when galactose was used as a carbon source. Overexpression of the transcriptional activator, GAL4, appeared to have only negative effects on the expression of the hirudin gene and lacZ directed by the GAL10 promoter in the strain used in this study, unlike the previously reported examples. The complex medium containing yeast extract used for the increase of the cell mass and hirudin level did not show any detrimental effect on plasmid stability and did not complicate the downstream purification of hirudin from the culture supernatant. Moreover, the complex medium could greatly improve the hirudin productivity and reduce the degradation of hirudin produced in the culture supernatants.

Animals↗
PubMed1993

Nucleotide sequence of levansucrase gene (levU) of Zymomonas mobilis ZM1 (ATCC10988).

The extracellular levansucrase gene (levU) was cloned from the genomic DNA of Zymomonas mobilis ZM1 and the nucleotide sequence of the levU structural gene was determined. The 3.1 kb EcoRV-polylinker fusion DNA fragment containing the levU gene had an open reading frame of 1272 bps and the deduced amino acid sequence was 423 residues long with a molecular weight of 46,725. Although this protein exhibited little similarity with other known levansucrases, several well-conserved regions were observed (1-5 regions).

Amino Acid Sequence↗
PubMed1984

A natural course of a dislocated healed tuberculous hip in a child. A case report.

Subluxation was once a common complication of the tuberculous hip, even when properly treated. A review of the English literature failed to disclose the corrective process of development of the hip joint following a debridement operation. A three-year-old boy having a proven tuberculous hip had his hip dislocated after joint debridement. In the ensuing ten years, the luxated head spontaneously reduced to nearly normal position. Transitory capsular laxity was believed to cause the dislocation in this case, while growth and development led to spontaneous reduction. A decade may elapse before relocation is complete.

Child, Preschool↗
PubMed1980

Effect of environmental pH on fermentation balance of Lactobacillus bulgaricus.

When Lactobacillus bulgaricus NLS-4 was grown anaerobically in continuous culture with limiting glucose, a shift in the pH of the medium from the acidic to the alkaline range caused this normally homofermentative bacterium to catabolize glucose in a heterofermentative fashion. The change in the nature of the fermentation was accompanied by a decrease in lactate dehydrogenase biosynthesis in alkaline conditions. The lactate dehydrogenase from this organism did not require fructose 1,6-diphosphate or manganese ions (Mn2+) for catalytic activity. Involvement of the phosphoroclastic split in the pyruvate conversion in an alkaline environment was also confirmed. The high lactate dehydrogenase synthesis in acidic medium together with the participation of the phosphoroclastic split under alkaline conditions may explain the shift from homolactic to heterolactic fermentation of L. bulgaricus NLS-4 with the change of environmental pH.

Adenosine Triphosphate↗
PubMed1980

Effect of environmental pH on chain length of lactobacillus bulgaricus.

Culture medium pH was found to affect strongly the chain length of lactobacillus bulgaricus NLS-4 cells. The organism was cultured continuously in glucose-limited complex medium of different pH's with constant agitation at 250 rpm under anaerobic headspace. The cell chains increased their lengths with an increase in pH and yielded clumps of folded filaments at pH above 8.0. Involvement of an autolytic enzyme(s) in the separation of L. bulgaricus cells was confirmed, and the poor synthesis of this enzyme(s) under alkaline culture conditions could explain the pH-related filamentous growth of this organism.

Culture Media↗
PubMedDate not supplied

Structure and nuclear localization signal of the SKI3 antiviral protein of Saccharomyces cerevisiae.

The yeast chromosomal genes SKI2, SKI3, SKI4, SKI6, SKI7 and SKI8 repress the replication of double-stranded RNA viruses, protecting the host from the otherwise lethal effects of the virus. We cloned and sequenced the SKI3 gene and found that it encodes a 163 kDa protein including a typical nuclear localization signal. Cell fractionation experiments show that the SKI3 gene product is indeed tightly associated with nuclei and that the putative nuclear localization sequence directs beta-galactosidase into the nucleus. However, fusion of a part of the SKI3 protein lacking this signal with beta-galactosidase also directs beta-galactosidase into the nucleus, suggesting the presence of a second nuclear localization signal. The SKI3 gene is only essential in the presence of an M double-stranded RNA virus.

Amino Acid Sequence↗
PubMedDate not supplied

Desulfurization of diesel oils by a newly isolated dibenzothiophene-degrading Nocardia sp. strain CYKS2.

A dibenzothiophene (DBT)-degrading bacterial strain was isolated from dyeing industry wastewater and identified as Nocardia sp. CYKS2. The newly isolated bacterial strain Nocardia sp. CYKS2 was able to convert DBT to 2-hydroxybiphenyl (2-HBP) as the dead-end metabolite through a sulfur-specific pathway. Other organic sulfur compounds, such as thiophene derivatives, thiazole derivatives, sulfides, and disulfides were also desulfurized by Nocardia sp. CYKS2. In batch culture, 0.2 mM DBT was completely desulfurized in 60 h. After DBT was depleted, neither cell growth nor 2-HBP production was observed. When a model oil which DBT was dissolved in hexadecane was treated with growing cells, DBT was desulfurized from 10 mM to about 2 mM in 80 h. In this case, desulfurization rate was 0.279 mg-sulfur/(L-dispersion.h), which was about 2.5 times higher than that in the previous case of batch culture. When diesel oil was treated, the sulfur content decreased from 0.3 to 0.24 wt % in 48 h. A volumetric phase ratio of oil to water was 1/10 in this case. The sulfur decreased from 0.3 to 0.2 wt % in 48 h, when the volumetric phase ratio was 1/20. The desulfurization rates were 0.909 and 0.992 mg-sulfur/(L-dispersion.h), respectively.

Biodegradation, Environmental↗