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Biomedical subjects

J C Chae

Publications and source records attributed to J C Chae.

8 recordsLinked to original sources
PubMed2000

Genetic structure and functional implication of the fcb gene cluster for hydrolytic dechlorination of 4-chlorobenzoate from Pseudomonas sp. DJ-12.

The fcb gene cluster responsible for the hydrolytic dechlorination of 4-chlorobenzoate (4CBA) was cloned from the chromosomal DNA of Pseudomonas sp. DJ-12, and its nucleotide sequence analyzed. The gene cluster was organized in the order fcbB-fcbA-fcbT1-fcbT2-cbT3-fcbC, which is different from that reported in other bacteria. A promoter-like sequence (-35 and -10 region) is located upstream of the fcbB gene and putative ribosome-binding sequences were found upstream of the respective orfs. A stem-loop transcription terminator structure is found downstream of fcbC. This suggests that the six orfs are transcribed into a polycistronic mRNA. The FcbA, FcbB, and FcbC enzymes for dechlorination of 4CBA have a relationship in common with the enzymes involved in fatty acid metabolism on the basis of their deduced amino acid sequences. The proteins encoded by fcbT1, fcbT2, and fcbT3 show similarity to those encoded by dctP, dctQ, and dctM of Rhodobacter capsulatus respectively, which encode transporter proteins for C4-dicarboxylate. It is likely, therefore, that these proteins of DJ-12 play a role in transport of 4CBA into the cell.

Biological Transport↗
PubMed1999

Cloning and sequencing of the fcbB gene encoding 4-chlorobenzoate-coenzyme A dehalogenase from Pseudomonas sp. DJ-12.

Pseudomonas sp. DJ-12 degrades 4-chlorobenzoate through hydrolytic dechlorination to produce 4-hydroxybenzoate and a chloride ion. The fcbB gene encoding the 4-chlorobenzoate-coenzyme A (4CBA-CoA) dehalogenase which catalyzes the nucleophilic substitution reaction to convert 4CBA-CoA to 4-hydroxybenzoate-coenzyme A (4HBA-CoA) in the consecutive steps of dechlorination was cloned from the chromosome of the organism. A nucleotide sequence analysis of the gene showed an open reading frame consisting of 810 nucleotides, which can encode for a polypeptide of molecular mass 30 kDa, containing 269 amino acid residues. A promoter-like sequence (-35 and -10 region) and a putative ribosome-binding sequence were identified. A deduced amino acid sequence of the 4CBA-CoA dehalogenase showed 86%, 50%, and 50% identity with those of corresponding enzymes in the Pseudomonas sp. CBS3, Arthrobacter sp. SU, and Arthrobacter sp. TM1, respectively.

Amino Acid Sequence↗
PubMed1996

Structure of the pcbC gene encoding 2,3-dihydroxybiphenyl dioxygenase of Pseudomonas sp. P20.

Pseudomonas sp. P20 is a soil bacterium growing in biphenyl or 4-chlorobiphenyl as the sole carbon and energy source, where the initial catabolism of biphenyl to form benzoate is catalyzed by four enzymes encoded in the pcbABCD gene cluster. The nucleotide sequence of the 2,3-dihydroxybiphenyl dioxygenase gene corresponding to the pcbC gene was determined. The pcbC gene was composed of 921 base pairs with an ATG initiation codon and a TGA termination codon, which can encode a polypeptide of molecular mass 34 kDa containing 306 amino acids. A promoter-like sequence and ribosome-binding sequence were identified upstream of the initiation codon. The deduced amino acid sequence of 2,3-dihydroxybiphenyl dioxygenase exhibited 47% identity with that of corresponding enzyme of Pseudomonas sp. DJ-12, and less than 35% identity with those of other extradiol-type dioxygenases.

Amino Acid Sequence↗
PubMed1992

Enhanced ingrowth of porous-coated CoCr implants plasma-sprayed with tricalcium phosphate.

Tricalcium phosphate (TCP) is an osteo-conductive bioceramic which, when applied to a porous-coated prosthesis, may enhance osseous ingrowth and mechanical stability. TCP plasma-sprayed and unsprayed porous-coated tibial intramedullary rods were bilaterally implanted in seven adult rabbits. All rabbits were killed at 12 weeks. Pull-out tests were performed on 4 rabbits while all were evaluated histologically for osseous response and adverse tissue reaction. TCP-sprayed implants showed significantly greater osseous ingrowth in comparison to unsprayed implants. Neither implant type exhibited adverse tissue reactions. Average pull-out strengths were 69 lb for treated rods and 72 lb for controls (p greater than 0.05); quality of fit for all pull-out specimens except one was deemed poor. We conclude that plasma-sprayed TCP enhances osseous ingrowth into porous-coated devices. However, our data further suggest that enhanced ingrowth may not always lead to enhanced fixation.

Alloys↗
PubMed1988

Efficacy of plasma-sprayed tricalcium phosphate in enhancing the fixation of smooth titanium intramedullary rods.

The osseous tissue response to intramedullary rods plasma-sprayed with TCP was investigated. TCP-sprayed smooth titanium rods and unsprayed controls were bilaterally implanted into the medullary canals of rabbit tibiae. Rabbits in the short-term study were sacrificed at 3 weeks; rabbits in the long-term study were sacrificed at 12 weeks. Pull-out tests were performed and histological sections prepared. The TCP-sprayed titanium rods exhibited significantly higher pull-out strengths than unsprayed contralateral rods at both 3 and 12 weeks, suggesting the bonding of bone to the TCP layer. The TCP-sprayed titanium rods at 3 weeks showed significantly greater osseous tissue response than unsprayed contralateral controls. At 12 weeks, the osseous tissue response was greater than at 3 weeks, and, surprisingly, the response to TCP-sprayed and unsprayed titanium rods was comparable.

Animals↗
PubMed1988

Macroscopic and microscopic evidence of prosthetic fixation with porous-coated materials.

The host response to porous-coated prostheses appears favorable; there is little evidence of any adverse tissue response or significant osteoclastic activity except in grossly loose specimens. While the nature of retrieval specimens makes any statistical correlation problematic, some generalizations can be made. Femoral hip prostheses are most likely to present bone ingrowth along the lateral quadrant of their porous coating. The frequency of bone ingrowth of femoral components was nearly twice that of acetabular devices. Pore size, geometry, and porous-coating composition did not appear to influence the appearance of bone and fibrous tissue ingrowth. Direct bonding of bone to the uncoated portion of the prosthesis was rarely seen and occurred only in closest proximity to the porous-coated regions. Indications of pain and looseness are evidence that fibrous tissue ingrowth alone is not always sufficient to ensure stability. Additionally, some bone-ingrown prostheses were retrieved because of pain, which leads to the conclusion that local bone ingrowth cannot ensure a general freedom from pain, especially with partially coated prostheses. Bone and fibrous tissue response to the porous coatings generally consists of interdigitation, while the response to uncoated regions is fibrous tissue encapsulation. Burnishing the distal tips of many of the partially coated femoral prostheses is an indication of relative motion in that region, which may be a potential source of pain.

Acetabulum↗
PubMedDate not supplied

Physiatry as a primary care specialty.

The ongoing changes in health care seek to create an affordable, accessible, and high-quality health care delivery system for all Americans. In response to this, Physical Medicine and Rehabilitation (PM&R) is re-examining its role in the provision of health care to the disabled, particularly the severely affected. We surveyed 100 physiatrists and 100 PM&R residents across the country regarding their opinions on the competence, qualifications, and desire of physiatrists to provide primary care for the disabled. Fifty-five physiatrists and 51 residents responded (55% overall). Thirty-nine percent of all respondents agreed that PM&R should be designated as a primary care specialty, and 53% believed that physiatrists should provide primary care to the severely disabled (e.g., spinal cord and head injury). Overall, 53% felt that physiatrists are competent in general medical care, but 38% are convinced that the current 4-yr PM&R residency training sufficiently prepares physiatrists to assume the role of a primary care provider. Of the patient populations considered, the respondents thought that physiatrists should manage the care of spinal cord injury (60%) and head injury (51%), but only 40% were willing to assume primary care responsibilities.

Health Care Reform↗