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Biomedical subjects

L Ko

Publications and source records attributed to L Ko.

27 records · Page 2Linked to original sources
PubMed1990

Purification and chemical modification of porcine bone morphogenetic protein.

Implantation of porcine bone morphogenetic protein (pBMP) in the muscle induces differentiation of mesenchymal-type cells and results in endochondral bone formation. pBMP was isolated from porcine demineralized bone matrix and purified by hydroxyapatite chromatography, Sephadex G75 gel filtration, preparative sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), preparative isoelectric focusing (IEF), and chromatofocusing fast protein liquid chromatography (FPLC). Porcine BMP has an MW of 26 K and a range of pI from 4.65 to 4.73 determined by SDS-PAGE and IEF, respectively. Reconstitution with the citrate buffer supernatant fraction enables as little as 50 micrograms of the soluble pBMP fractions to induce osteogenesis in an in vivo assay. Chemical modification studies indicate that the osteoinductive potential of the pBMP molecule depends on tyrosine, carboxyl groups, and disulfide bonds and can be increased by modification of sulfhydryl groups. Modification of arginine and tryptophan has no effect on bioactivity. By pepsin-limited proteolysis, fragments of pBMP with an MW of 6-14 K show definite, although reduced, BMP activity.

Animals↗
PubMed1982

Butyrate-induced increase in neuron-specific enolase and ornithine decarboxylase in anaplastic glioma cells.

Butyrate treatment results in the rapid formation of processes on F98 anaplastic glioma cells. The morphological differentiation occurs more rapidly and to a greater extent than that induced by nerve growth factor (NGF). The incorporation of [3H]thymidine is virtually stopped 1 day after treatment of F98 cells with sodium butyrate. Butyrate also caused a large increase in ornithine decarboxylase activity in F98 cells between 6 and 12 h after treatment. This was inhibited by both cycloheximide and actinomycin-D. NGF did not cause these effects. Butyrate also caused an increase in neuron-specific enolase (NSE) content in F98 cells. This effect appeared to be specific for butyrate. Since NSE induction is characteristic only of neurons and neuroendocrine cells, this finding indicates that butyrate is capable of inducing biochemical differentiation along neuronal lines in undifferentiated glioma cells.

Animals↗
PubMed1980

Characterization of cell cycle and biological parameters of transplantable glioma cell lines and clones.

Aberrant biological characteristics of established cell lines and clones, derived from nitrosourea-induced gliomas in CDF rats were compared with normal rat glial cells. Despite their tumorigenicity and unrestrained proliferation due to inherent cytogenetic anomalies, these neoplastic cells retained certain normal glial attributes to a variable degree. Differentiated glioma cells resembled normal glial cells to a greater extent than they resembled anaplastic glioma cells. They were also less malignant upon implantation. Cell cycle analyses revealed that considerable variations not only for the G1 phase but also for the S period were demonstrated among different tumor cell types. Shortening of the G1 phase may dictate a shorter generation time (shorter doubling time) since a larger potential proliferative pool may overcome the effect of a prolonged generation period may constitute a faster proliferation rate. Although the cell generation period of neoplastic cells is not necessarily shorter than that of normal glial cells, the lower proportion of nonproliferative cells results in a much faster growth rate when compared wo non-neoplastic glial cells in culture.

Animals↗
PubMedDate not supplied

Strategies of information disclosure to Chinese cancer patients in an Asian community.

There is little information available on strategies of information disclosure used by doctors in the care of patients with cancer. This report focuses on the style of disclosure used by doctors when giving diagnostic and prognostic information to patients with cancer. Among 46% of 133 surgeons and radiotherapists interviewed, disclosure of diagnosis involved a sudden approach (information given outright at one sitting). Less commonly used (19%) was a gradual disclosure style. Of the remainder who disclosed, more than half did so through the family or left it to the family to tell the patient. Doctors' specialty and patients' requests for prognostic information dictated disclosure style most frequently. Single people were more likely to have information disclosed to their families than were married people. While anecdotal accounts indicate negative reactions on the part of patients are a major reason for withholding such information, different disclosure style had little effect on doctors' reports of patient reactions to the bad news. Doctors perceived 25% of patients appeared to react 'with depression' but the remaining 75% appeared 'calm'. These results suggest patients are more likely to be told bad news suddenly, and that doctors do not perceive that this impacts too negatively on patients. The high levels of reported preference for information about cancer in Hong Kong (Fielding and Hung, 1996) conflict with actual prevalence patterns. It seems that commonly cited anecdotal reasons for withholding information from cancer patients in Hong Kong are not sustained by the data produced in these studies.

Adolescent↗
PubMedDate not supplied

Synovial T cell receptor heterogeneity in early arthritis.

Rheumatoid arthritis (RA) has been postulated to result from a synovial immune response to an unidentified antigen(s), which should be mirrored by the T cell response. Here we investigate the T cell receptor (TCR) repertoire in the synovial tissue of patients with arthritis of early to moderate duration. We developed a nested polymerase chain reaction (PCR) technique to examine the TCR repertoire of small biopsy specimens, and show that the method is highly sensitive. We apply this technique to synovial biopsies obtained from the knee joints of patients with early to moderate duration arthritis (average duration of arthritis 1 year, range 0. 02-2.75 years). We examined biopsies from 5 normal individuals, 32 RA patients, 7 patients with seronegative spondyloarthropathy (Sp), and 12 patients with undifferentiated arthritis (UA). TCR message was detectable in 4/5 normals, 15/32 RA, 5/7 Sp, and 8/11 UA biopsies, with sampling error likely accounting for most negative biopsies. The average numbers of TCR Vbetas detected per TCR-positive biopsy were 5.0 +/- 3.7 for normals, 12.7 +/- 8.4 for RA, 18.0 +/- 7.4 for Sp patients, and 14.4 +/- 10.2 for UA. Examination of TCR messages by single-stranded conformational polymorphism analysis showed similar proportions of dominant clones in the normals compared with the patients with inflammatory arthritis. Sequence analysis was performed on 33 dominant clones from 16 patients. Sequence alignment of the third hypervariable regions showed some evidence of disease-specific sequence clustering for Sp, while some RA sequences showed similarity to previously described motifs. These data indicate greater TCR heterogeneity in early Sp and UA compared with normal synovium. Disease-specific TCR sequences may occur in early RA and Sp.

Adult↗