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Biomedical subjects

K Song

Publications and source records attributed to K Song.

117 records · Page 7Linked to original sources
PubMed1990

Complementary DNA cloning of a receptor for tumor necrosis factor and demonstration of a shed form of the receptor.

Tumor necrosis factor (TNF) receptor (TNFR) was isolated as a 68-kDa glycoprotein from UC/HeLa 2-5 cells developed from a parental B-cell line (UC cells) to overexpress the receptor. Tryptic digests of two separate TNFR preparations provided amino acid sequences of four different peptides. Amino-terminal analysis indicated the presence of the amino-acid sequence Val-Ala-Phe-Thr-Pro, reported to be the amino-terminal sequence of a 30-kDa urinary TNF-binding protein II. Examination of the cultured medium of UC/HeLa 2-5 cells showed an abundance of a 40-kDa TNF-binding protein, indicating that the previously cited 30-kDa TNF-binding protein II is likely to be a shed form of the TNFR. Based on the peptide sequences, oligonucleotides were synthesized, and two of these were used as primers in the polymerase chain reaction to amplify cDNA sequences from poly(A)+ RNA of UC/HeLa 2-5 cells. These PCR fragments were radiolabeled and used to screen a cDNA library made from UC/HeLa 2-5 mRNA. Further analysis identified cDNA sequences that encoded the amino acid sequences of all four TNFR peptides. RNA blot-hybridization analysis of UC/HeLa 2-5 mRNA revealed a 3.8-kilobase transcript of the same size as the mRNA in the parental UC cells. Genomic Southern blots indicated the presence of a single gene in parental cells and a second, amplified gene in TNFR-overexpressing cells, suggesting amplification of the transfected gene as a possible mechanism for the increase in TNFR numbers in UC/HeLa 2-5 cells.

Amino Acid Sequence↗
PubMed1990

[Changes of Ca2(+)-ATPase and calmodulin in erythrocytes and their responses to nifedipine in essential hypertension].

The Ca2(+)-ATPase activity and calmodulin (CaM) of erythrocytes and the effect of nifedipine on them were studied in subjects with essential hypertension (EHT). The results showed that both the basal and maximal Ca2(+)-ATPase activities of erythrocytes were lower in subjects with EHT than those in normal controls, and Ca2+a-ATPase activities were negatively correlated with blood pressure; the content of CaM was also reduced, and it was positively correlated with maximal Ca2(+)-ATPase activity. The basal Ca2(+)-ATPase activity was improved with nifedipine, but the maximal Ca2(+)-ATPase activity and CaM content were both unchanged significantly. Thus, the Ca2(+)-ATPase and CaM of erythrocytes might play an important role in EHT, and nifedipine has a mild effect on cellular calcium transporting.

Adult↗
PubMed1982

Cancer mortality among Koreans in Osaka, Japan.

Using data from the Osaka Cancer Registry, we calculated age-standardized cancer mortality rates among Koreans and Japanese living in Osaka, Japan, during 1968-77. The following points were elucidated: 1) Among Koreans in Osaka, the mortality rate for liver cancer was about twice that among Japanese; 2) Among Koreans in Japan, the mortality rate of stomach cancer has been declining more rapidly than it has among Japanese. The factors involved in the Korean-Japanese difference of liver cancer and those involved in the rapid decrease of stomach cancer among Koreans in Japan are discussed.

Adult↗
PubMedDate not supplied

In vitro autoradiography reveals predominantly AT1 angiotensin II receptors in rat kidney.

Angiotensin II (Ang II) receptor subtypes in the rat kidney were investigated by using type 1 (AT1) and type 2 (AT2) Ang II receptor antagonists to discriminate specific 125I-[Sar1,Ile8] Ang II binding sites with in vitro autoradiography. DuP 753, a nonpeptide Ang II antagonist specific for the AT1 sites, potently displaced binding in glomeruli (Ki = 23.9 +/- 3.3 nM) and proximal tubules (Ki = 43.4 +/- 17 nM). By contrast, the AT2 antagonists, PD 123177 and CGP 42112A, were very weak in competing for specific 125I-[Sar1,Ile8] Ang II binding sites. AT1 receptors, as determined in the presence of an excess concentration (10 microM) of the AT2 antagonist, PD 123177, account for 95% of total renal Ang II receptors, whereas AT2 receptors, as determined in the presence of an excess concentration (10 microM) of the AT1 antagonist, DuP 753, represent approximately 5% of total renal Ang II receptors. In addition, the reducing agent, dithiothreitol, produces a dose-dependent inhibition of Ang II receptor binding with an IC50 of 2 mM, a characteristic of the AT1 receptors. These findings indicate that the AT1 receptor is the predominant subtype at multiple anatomical sites in the rat kidney.

Angiotensin Receptor Antagonists↗
PubMedDate not supplied

Ankle-foot orthoses for preambulatory children with spastic diplegia.

We evaluated the effect of articulating and solid ankle-foot orthoses (AFOs) on the transitional movement of sit-to-stand for 15 children aged 2-5 years with spastic diplegia and dynamic equinus. Kinematic and kinetic data were collected for each child. The time to reach stable standing was determined by using a force plate. Seven children were comparable to age-matched normals while barefoot and were slowed by the use of AFOs. Eight patients were more than 1 standard deviation slower than normals while barefoot. All were significantly (p < 0.003) improved by the use of articulating AFOs. The clinical difference between these groups was the presence of equinus during stable standing while barefoot for patients aided by AFOs, whereas the second group remained plantigrade barefoot. We conclude that children with spastic diplegia with uncontrolled dynamic equinus benefit from the use of articulating AFOs for the movement of sit-to-stand.

Age Factors↗
PubMedDate not supplied

Comparative study of conventional hip-knee-ankle-foot orthoses versus reciprocating-gait orthoses for children with high-level paraparesis.

We evaluated eight children with thoracic or high lumbar-level paraparesis for metabolic performance while ambulating with custom fabricated thermoplastic hip-knee-ankle-foot orthoses (HKAFOs) and reciprocating-gait orthoses (RGOs). Seven of the eight children had myelomeningocele. Each patient was tested in both systems at self-selected speeds in a crossover study design. At self-selected speeds, the level of exercise intensity for both thoracic and high-lumbar patients with either orthosis was lower than that for normal children. The average metabolic cost of walking in the RGO was twice that of normal children, as compared with six times normal in HKAFOs. For the four thoracic-level patients, there was a significantly higher oxygen cost of ambulation in using HKAFOs versus RGOs. No significant difference in metabolic performance was found for the high-lumbar patients. Velocity of ambulation was faster in the RGOs than in the HKAFOs. For thoracic-level patients, our data suggest that an RGO will provide a faster, more energy-efficient gait than a statically locked HKAFO. For high-lumbar patients, no significant difference was found between the two orthoses. Seven of eight children preferred the RGO over the HKAFO.

Biomechanical Phenomena↗
PubMedDate not supplied

Role of wild-type p53 in the enhancement of camptothecin cytotoxicity against human prostate tumor cells.

The role of wild-type human p53 protein in enhancing camptothecin cytotoxicity was examined by infecting human prostate PC3 cells with adenovirus expressing human wild-type p53 gene (Adwtp53). The prostate PC3 cells are null for p53 gene. Infection induced the synthesis of both wtp53, and WAF1 (p21) proteins, resulting in growth arrest of PC3 cells. In the presence of camptothecin, an inhibitor of topoisomerase 1, significant increases in both p53 and p21 proteins were detected in Adwtp53-infected PC3 cells. While Adwtp53 and camptothecin, as single agents, caused apoptosis and cell death, combinations of camptothecin and Adwtp53 were better in inducing apoptosis and cell death in PC3 cells. In contrast, cisplatin neither stabilized p53 and p21 proteins nor enhanced DNA fragmentation when combined with Adwtp53 in PC3 cells, indicating specificity for camptothecin. These observations suggest that introduction of wild-type p53 gene with topoisomerase I inhibitors may offer a clinical advantage for the treatment of prostate tumors containing mut53 or null for p53 gene.

Adenoviridae↗