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Biomedical subjects

Y J Choi

Publications and source records attributed to Y J Choi.

At least 109 records · Page 6Linked to original sources
PubMed1995

The 3'-untranslated region of rat lysyl oxidase cDNA.

The cloning of the 3'-untranslated region of rat lysyl oxidase cDNA was completed. cDNA clones were generated by reverse transcriptase PCR from neonatal rat aorta smooth muscle cell RNA, and sequenced. Several polyadenylated clones were obtained, providing 2.1 kb of new sequence. Clones were polyadenylated at three different positions. The cDNA clones were verified by PCR-cloning and sequencing of genomic DNA, and by Northern blotting studies. Evidence is presented that the polyadenylation patterns of rat lysyl oxidase mRNAs are similar, but not identical to mouse or human transcripts. Interestingly, the nonconsensus polyadenylations in rat did not occur at the same positions as was found in mouse lysyl oxidase cDNAs. Multiple transcription initiation sites were found by primer extension mapping. Thus, the complex pattern of rat lysyl oxidase mRNAs on Northern blots is principally due to differential use of polyadenylation signals, and to the occurrence of multiple transcription initiation sites. All clones lacked a previously reported 258 bp segment nearly identical to a conserved segment of the 3'-untranslated region of elastin cDNA. We conclude that the elastin-like sequence previously reported in rat lysyl oxidase cDNA is not a species-specific sequence, and most probably resulted from spurious ligation reactions during construction of the cDNA library.

Animals↗
PubMed1995

Effect of intermittent and stepwise administration of a beta-adrenergic agonist, L644,969, on rat growth performance and skeletal muscles.

The effects of intermittent and stepwise administration of a beta-adrenergic agonist, L644,969 on rat growth performance and skeletal muscle growth were investigated in two studies. In experiment 1, 34 juvenile male rats were randomly assigned to two treatment groups: (1) control, 0 ppm L644,969 for 21 days; (2) BL10, 10 ppm of L644,969 for 7 days, then 0 ppm L644,969 for another 7 days, plus 10 ppm of L644,969 for the final 7 days. L644,969 increased (P < 0.05) weight gain during the 7 day initial administration period. When L644,969 was withdrawn, no difference in weight gain was observed between the two groups. Re-administration of L644,969 after the withdrawal period increased (P < 0.01) weight gain up to 3 days of re-administration, but no effect was observed thereafter. In experiment 2, 18 juvenile female rats were divided into three groups: (1) control, 0 ppm L644,969 for 22 days; (2) BL10, 10 ppm L644,969 for 22 days; (3) BL10-60, 10 ppm L644,969 for 11 days, then 60 ppm L644,969 for another 11 days. Feeding 10 ppm L644,969 increased (P < 0.05) the rate of weight gain up to 11 days, but not thereafter. Raising the dose of L644,969 from 10 to 60 ppm increased body weight gain during the initial 8 day period, but no effect was observed thereafter. Weights of skeletal muscles and heart were significantly increased by 10 ppm L644,969. Raising the dose to 60 ppm increased the mean skeletal muscle weights without statistical significance. Muscular concentration of cAMP was significantly decreased by the long-term administration of L644,969.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Agonists↗
PubMed1995

Antihepatotoxic activity of icariin, a major constituent of Epimedium koreanum.

In an attempt to identify compounds with antihepatotoxic activity, carbon tetrachloride-induced cytotoxicity in primary cultured rat hepatocytes has been adopted as a screening system. Using this screening system, an antihepatotoxic compound from the aerial parts of Epimedium koreanum has been isolated. This compound, icariin, is a flavonol glycoside. Its antihepatotoxic activity was first evaluated by measuring the release of glutamic pyruvic transaminase and sorbitol dehydrogenase from CCl4-intoxicated rat hepatocytes into the culture medium. Icariin significantly reduced the level of glutamic pyruvic transaminase and sorbitol dehydrogenase released resulting in a 76% protection from toxicity at concentration ranges from 1 microM to 20 microM. The antihepatotoxic activity of icariin was also estimated by the determination of total cytochrome P-450 content and glutathione-S-transferase activity in the CCl4-intoxicated hepatocytes.

Animals↗
PubMed1994

Isolation and characterization of two beta-tubulin cDNA clones from rice.

Two cDNA clones encoding two different beta-tubulins, RTUB-1 and RTUB-2, were isolated from a rice cDNA library and their nucleotide sequences were analyzed. The deduced amino acid sequences showed amino acid sequence identity between 92% and 97% with other plant beta-tubulins. Southern blot analysis using gene-specific and coding-region probes suggested that beta-tubulins in rice are encoded by multigene families. The two cDNA clones represent two subfamilies of rice tubulins, RTUB-1 and RTUB-2, consisting of 3 to 4 genes and a single gene, respectively. The transcript levels of RTUB-1 and RTUB-2 genes were higher in actively elongating tissues such as etiolated shoot tissues and light-grown root tissues of four-day old seedlings.

Amino Acid Sequence↗
PubMed1994

The effect of lactogenic hormones on protein synthesis and amino acid uptake in rat mammary acinar cell culture at various physiological stages.

1. The activities of protein synthesis and amino acid uptake at various physiological stages were determined by the incorporation of radioactive materials ([3H]-lysine, [14C]-cycloleucine) in rat mammary epithelial cell cultures. The activity of protein synthesis and amino acid uptake was higher in early lactation than in virgin, pregnant and late lactation stages. 2. Lactogenic hormones (prolactin, hydrocortisone and insulin) treatment related with mammary growth and differentiation increased the activities of protein synthesis and amino acid uptake. But increase of these activities was different at each physiological stage. 3. The effect of prolactin and hydrocortisone on the activities were greater in virgin, pregnant and late lactation than in early lactation. And effect of insulin was greater in pregnant and early lactation than in virgin and weanling.

Amino Acids↗
PubMed1994

Epstein-Barr virus associated posttransplant malignant lymphoma in renal allograft recipients.

We report two cases of posttransplant malignant lymphoma(PTML) of B cell origin associated with Epstein-Barr virus(EBV) infection. They were a 52-year-old male and a 37 year-old-female, in whom intermediate-grade diffuse malignant lymphomas of large cell type developed in the submandibular area and jejunum, respectively. DNA and RNA in situ hybridization revealed the presence of EBV-specific DNA and RNA sequences in the tumor cells.

Adult↗
PubMed1994

Five cases of cytomegalovirus infection detected by in situ hybridization and antigenemia assay.

We report five cases of cytomegalovirus infection in immunocompromised patients which were detected by either cytomegalovirus antigenemia assay or in situ hybridization. Four cases had leukemia and the other had chronic renal failure. All the three BMT recipients suffered from GvHD. Interestingly, there was an unique case of CMV disease without a history of BMT, which reminded us that CMV could attack immunocompromised patients who had not undergone transplantation, too. Four out of five cases died. We think that cytomegalovirus infection or disease should not be regarded as a minor problem in post-transplantation infection in Korea.

Adolescent↗
PubMed1994

Malignant fibrous histiocytoma in chordoma--immunohistochemical evidence of transformation from chordoma to malignant fibrous histiocytoma.

Sarcomatous transformation in chordoma (dedifferentiated chordoma) is a very rare condition and has been emphasized as a distinct entity because of its more aggressive clinical course. Here we describe a case of dedifferentiated chordoma (chordoma associated with malignant fibrous histiocytoma) arising from the sacrococcygeal region of a 55-year-old woman. The results of immunohistochemical stain in the chordoma area were strong positive for cytokeratin, epithelial membrane antigen and S-100 protein. The spindle and giant cells in the transitional areas of chordoma and malignant fibrous histiocytoma were positive for cytokeratin and epithelial membrane antigen in addition to vimentin and alpha-1-antichymotrypsin. The spindle and giant cells in the central area of malignant fibrous histiocytoma were negative for cytokeratin and epithelial membrane antigen, but positive for vimentin and alpha-1-antichymotrypsin. This supports the pathogenesis of sarcomatous transformation from chordoma.

Chordoma↗
PubMed1994

Clear cell sarcoma of the kidney--immunohistochemical study and flow cytometric DNA analysis of 7 cases.

Immunohistochemical study and flow cytometric DNA analysis were done on seven cases of clear cell sarcoma of the kidney (CCSK) to speculate its histogenesis and to access the diagnostic usefulness of these methods in the differential diagnosis of Wilm's tumor. Clinically, CCSK is a rare malignant renal tumor of children with a propensity to metastasize to bone. Arborizing vascular pattern surrounding the tumor cells which have clear cytoplasm is characteristic histologic finding. Immunohistochemically, only vimentin was diffusely demonstrated in the tumor cell membrane and cytoplasm. In flow cytometric DNA analysis, four cases showed diploidy and two cases near diploidy. CCSK is a separate disease entity with characteristic clinicopathologic, immunohistochemical and flow cytometric findings in distinction from Wilms' tumor. Considering the histologic and immunohistochemical findings, the possible histogenetic mechanism of CCSK seems to be in common with congenital mesoblastic nephroma (CMN), that is primitive mesenchymal cells which committed early stromagenic activity.

Child, Preschool↗
PubMed1994

Intraocular hemocoagulase in human vitrectomy.

A prospective study was performed to establish the effects on the bleeding time and the ocular toxicity of the use of intravitreal hemocoagulase (1 NIH thrombin unit/100 ml in BSS Plus) in patients undergoing vitrectomy. Sixty patients with diabetic retinopathy, penetrating ocular injury or non-diabetic retinal vascular disorder, in whom electroretinograms were recordable, were assigned to a study of Hemocoagulase-BSS Plus versus BSS Plus. The bleeding time was measured after cutting the proliferative attachments to the underlying retina. Intravitreal hemocoagulase significantly reduced the bleeding time, and this reduction of bleeding facilitated the surgery. A washout of hemocoagulase at the completion of the vitrectomy was not carried out. Hemocoagulase in the vitreous cavity assisted in maintaining hemostasis during the first week after diabetic vitrectomy. Postoperative electroretinography data did not show any disadvantage for the hemocoagulase infusate. Clinical study showed no adverse effect on the cornea, lens or visual acuity.

Adolescent↗
PubMed1993

Effect of long-term administration of somatostatin analogue on renal enlargement in uninephrectomized-diabetic rats.

Recent study has demonstrated that the long-acting somatostatin analogue administration effectively prevented initial renal growth in diabetic and uninephrectomized rats. In the present study we examined long-term effect of somatostatin analogue (Sandostatin) on renal enlargement in uninephrectomized-diabetic rat5. Animals were divided into 4 groups: (1) normal control rats (C) (n = 7), (2) uninephrectomized rats (NPX) (n = 7), (3) uninephrectomized-diabetic rats (NPX + DM) (n = 7) and (4) NPX + DM rats treated with Sandostatin (NPX + DM + Tx) (n = 9). All animals had free access to diet (50% protein) and water during the experimental period. To the NPX + DM + Tx rats, 2.5 micrograms of Sandostatin was given subcutaneously twice a day for 8 weeks. Periodic observations were done at 0, 4 and 8 weeks. After 8 weeks. NPX rats (0.540 +/- 0.017 (SEM)) had higher fractional kidney weights (FKW) (wet kidney wt/body wt) compared to C rats (0.410 +/- 0.014) (p < 0.0005), and both NPX + DM rats (0.983 +/- 0.098) and NPX + DM + Tx rats (1.091 +/- 0.042) had higher FKW compared to C rats (p < 0.0001) and NPX rats (p < 0.005), respectively. But no significant change of FKW was observed between NPX + DM rats and NPX + DM + Tx rats. Systolic blood pressure, BUN, serum creatinine, glomerular filtration rate and 24 hour urine protein excretion in NPX + DM rats were not different from those in NPX + DM + Tx rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Overproduction of indole acetic acid in Azospirillum lipoferum using the Escherichia coli trp operon.

A recombinant plasmid carrying the trp operon from Escherichia coli, which synthesizes tryptophan from chorismate, was constructed by using a broad host range plasmid vector pRK290; a mutant trp plasmid for tryptophan overproduction was then selected. The physiological, biochemical, and genetic properties of the Azospirillum lipoferum KY6, a potential nitrogen fixer of rice, harbouring the recombinant trp plasmid pMJC1 and its mutant pMJC101, were compared with those of the wild-type bacteria. Anthranilate synthetase is known to be the trpE gene product which plays a key role in the regulatory step in the feedback control of tryptophan biosynthesis. The enzyme activity of the Azospirillum lipoferum KY6 carrying pMJC1 or pMJC101 was respectively 7- and 30-fold higher than that of the wild type in the presence of 10(-4)M tryptophan. As expected, the amount of tryptophan biosynthesis in A. lipoferum KY6 (pMJC101) was increased approximately 100-fold as compared with the wild type, which led to overproduction of indole acetic acid even without addition of exogenous tryptophan. Moreover, the recombinant trp plasmid was fairly stable in A. lipoferum KY6 host, showing only 25% loss of the plasmid itself or the trp insert after 40 generations.

Azospirillum↗
PubMed1991

Detection of human papillomavirus DNA on routine Papanicolaou's smears by in situ hybridization with the use of biotinylated probes.

Specific human papillomavirus (HPV) types have been implicated as playing a major role in the development of cervical neoplasias. HPV DNA types usually have been identified by nucleic acid hybridization assays with the use of radiolabeled probes. These techniques are sensitive and specific but are not suitable for large-scale clinical use. To detect specific HPV DNAs simply and rapidly, in situ hybridization (ISH) with the use of biotinylated HPV DNA 6/11 and 16/18 probes was done on destained Papanicolaou's (Pap) smears from 545 patients. All smears showed koilocytotic changes. HPV DNAs were demonstrated not only in cervical intraepithelial neoplasia (CIN) and atypia, but also in squamous cells with minimal nuclear changes (karyomegaly) and perinuclear halos. HPV DNA 16/18 was detected in 52% of the smears with CIN I, 44% of those with CIN II and III, 19% of those with atypia, and 4% of the minimal changes. HPV DNA 6/11 was detected in 27% of the smears with CIN I, 27% of those with atypia, and 6% of the minimal changes. HPV DNAs were also detected in smears without koilocytotic changes. Thus, ISH with the use of biotinylated probes can serve as an adjunct to Pap smears in detecting HPV infection.

DNA Probes↗
PubMed1991

Malignant glomus tumor originating in the superior mediastinum--an immunohistochemical and ultrastructural study.

An extremely rare case of malignant glomus tumor originating in the superior mediastinum was evaluated immunohistochemically and ultrastructurally. A 78-year-old woman who had been suffering from dysphagia and dyspnea had poorly-defined soft tissue mass, 4.5 x 2.5cm, in the superior mediastinum with direct invasion into the esophagus, trachea, and bilateral thyroid glands. This case is believed to be unique in several respects. There were neither recognizable findings of benign glomus tumor nor sarcomatous areas, in contrast to the previously reported cases. A definite direct invasion into the surrounding organs was identified. We therefore interpreted this case as primary malignant glomus tumor, not as glomangiosarcoma arising in a benign glomus tumor.

Actins↗
PubMed1990

In situ hybridization using a biotinylated DNA probe on formalin-fixed liver biopsies with hepatitis B virus infections: in situ hybridization superior to immunochemistry.

In situ hybridization (ISH) using a biotinylated hepatitis B virus (HBV) DNA probe was compared with immunohistochemistry (IHC) using antibody to HBsAg in liver biopsies of 98 patients with HBV-related hepatitis. The positive reaction for ISH and/or IHC was demonstrated in 83 cases from 98 cases studied. In 60 cases, the findings of ISH and IHC were concordant, and in 20 cases, ISH showed evidence of HBV infection by detecting HBV DNA, but IHC did not. The study here confirms the advantages of ISH detecting HBV-DNA over IHC detecting HBsAg. Since ISH using biotinylated probe is simple and rapid, it may be used as a routine diagnostic procedure.

Biopsy↗