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Biomedical subjects

J Yoo

Publications and source records attributed to J Yoo.

At least 73 records · Page 4Linked to original sources
PubMed1997

p53 gene mutations and p53 protein expression in human soft tissue sarcomas.

OBJECTIVE: To determine the frequency of mutation and overexpression of the p53 tumor suppressor gene in human soft tissue sarcomas. DESIGN: A total of 31 soft tissue sarcomas were analyzed by immunohistochemistry for the expression of p53 protein and were subsequently investigated by the polymerase chain reaction technique and direct sequence analysis of exons 5 through 8 in the p53 gene. SETTING: The specimens were collected over a 3-year period in the laboratories at our large teaching hospital in Seoul, Republic of Korea. PATIENTS: Thirty-one patients with soft tissue tumor were surgically treated and diagnosed as having either malignant fibrous histiocytoma, rhabdomyosarcoma, or leiomyosarcoma. RESULTS: Overexpression of p53 was seen in 17 (55%) of 31 sarcomas, including 9 (64%) of 14 malignant fibrous histiocytomas, 4 (44%) of 9 rhabdomyosarcomas, and 4 (50%) of 8 leiomyosarcomas. Seven cases (23%) demonstrated mutations in the p53 gene. Six had a single mutation, whereas one showed triple mutations. There were seven mutations in exon 5, one in exon 6, and one in exon 7. All of the mutations were missense mutations, resulting in changes in the predicted amino acid sequence. Among the nine mutations, seven (78%) were transversions and two (22%) were transitions. CONCLUSIONS: Mutation of the p53 tumor suppressor gene, with resultant overexpression of p53 protein, frequently occurs in human soft tissue sarcomas, supporting the role of p53 mutations in the pathogenesis of soft tissue sarcoma and the possible usefulness of p53 immunolocalization as a screening method for p53 mutations.

Cell Nucleus↗
PubMed1996

Altered cytokine production and accessory cell function after HIV-1 infection.

We investigated cytokine production and accessory cell function in human macrophage hybridoma cell lines and primary monocytes after infection with HIV-1. HIV-1 infection induced IL-10 production in the macrophage hybridoma cell line with loss of IL-12 1 wk after infection. There were also significant increases in production of IL-10 (537 +/- 521 vs 687 +/- 625 pg/ml) while there was a reduction in IL-12 (6.3 +/- 3.1 vs 1.2 +/- 1.0 pg/ml, p = 0.021) in the primary monocytes 5 days after HIV-1 infection. In addition, the hybridoma cell lines and primary monocytes failed to support PHA, Con A, PWM, or anti-CD3- induced T cell proliferation 1 wk after infection. The viability of the T cells cocultured with the HIV-1-infected macrophage cell lines or the primary monocytes as determined by propidium iodide staining was unaltered and there was no increase in apoptosis-specific DNA strand breaks or increased expression of Bcl-2 in the T cells. No soluble suppressor factor was present, since UV-inactivated supernatants from the hybridoma cell line and primary monocytes failed to inhibit mitogen- and anti-CD3-induced T cell proliferation. Early events in T cell activation, including calcium flux and phosphotyrosine kinase activity, were intact in the T cells cocultured with the HIV-1- infected hybridomas and monocytes but there was reduced IL-2 production. Addition of exogenous IL-2 restored the proliferative responses. Taken together, these data suggest that alteration of cytokine production and accessory cell function for mitogens and anti-CD3-induced T cell proliferation independent of induction of apoptosis, suppressor factor production, or inhibition of T cell signaling occurs very early after HIV-1 infection and may contribute to the global immunosuppression observed in AIDS.

Apoptosis↗
PubMed1996

Dynamic changes in the locus control region of erythroid progenitor cells demonstrated by polymerase chain reaction.

The locus control region (LCR) far upstream of the human beta-like globin genes is defined by the preferential chromatin accessibility/DNase I hypersensitivity of four constituent DNA sites HS4, 3, 2, and 1. In an attempt to understand the mechanism of LCR function during early stages of erythropoiesis, a new polymerase chain reaction (PCR) method has been developed to examine the chromatin structure/DNase I hypersensitivity of the LCR in progenitor cells logistically available in limited cell numbers. In erythroid progenitors as well as in multipotent cells with erythroid potential, hypersensitive sites HS4, 3, 2, and 1 were present and the chromatin structure of the LCR was accessible. Moreover, the chromatin structure of the LCR underwent dynamic changes during erythropoiesis. In early erythroid progenitors, the HS2 site was more accessible than the HS3 site. In more mature erythroid progenitors, HS2 became less accessible than HS3 and the other sites. The results indicate that the transcriptional program of the globin genes is encoded, at least in part, in the chromatin accessibility of the LCR. This globin program was apparently initiated in multipotent cells and maintained in erythroid progenitors. Furthermore, the program could be modulated in response to cellular changes accompanying differentiation of the progenitor cells.

Adult↗
PubMed1996

Cloning and characterization of the bovine Fas.

Fas (APO-1, CD95), a member of the tumor necrosis factor (TNF) receptor superfamily, is a cell membrane protein that mediates programmed cell death (apoptosis). In an effort to characterize the possible role of Fas-mediated apoptosis in some important physiological processes in livestock, bovine Fas (bFas) cDNA was isolated and its nucleotide sequence determined. The predicted amino acid sequence encodes a 323-amino-acid protein that contains a leader peptide, a transmembrane domain, and three domains of cysteine-rich motif within the extracellular region. At the amino acid level, bFas is 57% and 50% identical to human (hFas) and mouse (mFas), respectively. Its expression is abundant in peripheral blood lymphocytes, lung, spleen, thymus, and ovary, but minimal in heart, liver, and brain. A polyclonal anti-bFas serum raised against the carboxy-terminal half of cysteine-rich motif I recognized a single 46-kD protein in bovine MDBK cells by Western blot analysis. To investigate the apoptotic activity of bFas, MDBK and bFas-transfected L929 cells were exposed to a monoclonal anti-hFas IgM. Unlike other cell culture systems, the antibody failed to trigger cell death in MDBK and bFas transfected L929 cells.

Amino Acid Sequence↗
PubMed1996

Genomic organization and chromosomal mapping of the bovine Fas/APO-1 gene.

The cell-surface protein Fas (APO-1) is a member of the tumor necrosis factor receptor (TNFR) superfamily and transduces apoptosis following binding of Fas ligand or exposure to certain anti-Fas antibodies. We have isolated the bovine Fas (bFas) gene and determined its genomic organization and chromosomal location. Our data indicate that bFas is a single-copy gene that contains 9 exons and spans approximately 31.5 kb. The 5'-flanking region lacks conventional TATA and CCAAT elements, but contains several putative regulatory elements, including multiple copies of Sp1, AP-2, E-box, and N-box consensus sites. Linkage analysis of two (CA) dinucleotide repeat microsatellites within intron 1 and physical assignment by fluorescence in situ hybridization (FISH) placed the bFas gene on bovine chromosome 26. Collectively, these data provide a basis for understanding the regulatory mechanisms that control bFas gene expression.

Animals↗
PubMed1996

Cloning and chromosomal mapping of bovine interleukin-2 receptor gamma gene.

Interleukin-2 receptor (IL-2R) gamma chain, a member of the cytokine receptor superfamily, forms a high-affinity receptor with IL-2R alpha and beta chains that plays an important role in interleukin-2 (IL-2) signal transduction. We have cloned and characterized the bovine IL-2Rgamma gene and corresponding cDNA. Bovine IL-2Rgamma is a single-copy gene that contains 8 exons and spans approximately 3.8 kb. The promoter region lacks conventional TATA and CCAAT consensus sites, but contains several regulatory elements that are recognition sites for the GATA binding proteins, AP-1 and AP-2. Physical assignment by fluorescence in situ hybridization (FISH) placed the bovine IL-2Rgamma gene on chromosome Xq23.

Amino Acid Sequence↗
PubMed1996

Characterization of a single-locus minisatellite DNA in Xenopus laevis.

We have cloned a minisatellite tandem array (XTA) from Xenopus laevis that contains approximately 200 copies of the 20-bp repeat 5'-CCAACAGCCTGCCCATCCAT-3'. The XTA sequence is present only once per haploid genome and is polymorphic with respect to repeat number and location of flanking restriction endonuclease sites. Although the 20-bp repeat has not previously been described, flanking sequences suggest that it lies proximal to coding regions in the Xenopus genome.

Animals↗
PubMed1996

Acute pancreatitis in chronic renal failure.

OBJECTIVE: To estimate the frequency and severity of acute pancreatitis (AP) associated with chronic renal failure (CRF) and to find out whether CRF causes AP. METHODS: We studied 532 patients with a first episode of AP during the period of 1982-1994. Twenty-one patients had CRF (endogenous creatinine clearance <15 ml/min); 511 patients without CRF served as controls (non-CRF). AP was diagnosed clinically and by elevation of amylase and lipase (3 times above upper limit of normal). CT or sonographic confirmation of diagnosis was made in all CRF patients. RESULTS: Cause of AP in the non-CRF group (ETOH 48.5%, biliary 32.9%, miscellaneous 18.5%) was significantly different (p < 0.001) from that seen in the CRF group (ETOH 33%, biliary 14.2%, and miscellaneous 52.3%). Incidence of severe AP in the two groups as assessed by >3 Ranson's criteria was 47.6% in the CRF group versus 21% in the non-CRF group (p < 0.005) and by simplified prognostic criteria it was 38 versus 10.3% (p < 0.005), respectively. Overall, CRF patients had more complications compared with non-CRF (66.6 vs. 26.8%, p < 0.005). CRF patients with severe AP had high mortality when stratified by either Ranson's >3 (70 vs. 11.1% p < 0.000) or simplified prognostic criteria >2 (87.5 vs. 20.8%, p < 0.0001). CONCLUSIONS: AP in CRF is frequently of unknown cause, suggesting the role of either CRF or other factors. Irrespective of cause, AP in CRF is a serious disease, associated with a high morbidity and mortality.

Acute Disease↗
PubMed1995

Oxidation of N-hydroxyguanidine by nitric oxide and the possible generation of vasoactive species.

It has been reported previously that the N-hydroxyguanidine function of N-hydroxy-L-arginine can react with nitric oxide (NO) to generate other species that can act as potent vasodilators with different biological lifetimes than NO. The identities of these species have yet to be determined. Therefore, we have studied the reaction between NO and N-hydroxyguanidine and determined that N-hydroxyguanidine is capable of reducing NO to yield nitrous oxide (N2O) and possibly other nitroso species. It is likely that at least some of the N2O formation in these reactions is due to the initial generation of nitroxyl (HNO). Since HNO has been shown to be a potent vasorelaxant, it is possible that some of the non-NO-mediated biological activity alluded to in previous studies was due to HNO and that other nitroso-species generated in the reaction may also contribute to the overall pharmacological activity by release of either NO or HNO.

Aerobiosis↗
PubMed1995

Impairment of monocytic function after influenza virus infection.

In order to analyze the immunosuppression associated with influenza virus infection, we investigated monocytic function in macrophage hybridoma cell lines 5 weeks after infection with two strains of influenza virus. Clones 30 and 63, chosen for stability in long-term culture, were infected with two strains of influenza virus, X-31 and PR-8. Uniform infection of both cell lines was confirmed by intracytoplasmic staining with the antihemagglutinin strain-specific monoclonal antibodies PY 102 and PY 206. One week after infection, clones 30 and 63 lost their ability to stimulate tetanus toxoid-specific major histocompatibility complex (MHC)-matched responder T cells. Coincident with the inability to stimulate MHC-matched T cells, there was diminished surface expression of class II MHC antigens and LFA-1-alpha and LFA-3 compared with that in uninfected cells: DR, 2.5 versus 10.6% (mean channel 0.3 versus 1.5); DQ, 1.6 versus 15.6% (mean channel 0.3 versus 3.0); DP, 5.0 versus 30.9% (mean channel 0.3 versus 2.0). LFA-1-alpha expression was reduced (13.1 versus 20.0%; mean channel 1.5 versus 2.0) while LFA-3 expression remained the same (22.2 versus 324%; mean channel 3.0 versus 3.3). Class I MHC surface antigen expression was unaltered. Cytokine secretion was also perturbed, as interleukin 1-alpha (IL-1-alpha) and IL-1-beta production was lost 1 week after infection. Production of IL-12 and IL-10 was unchanged, while IL-6 production was increased. The viability of the T cells cocultured with 63Flu was unaltered, demonstrating that the inability of the MHC-restricted T cells to proliferate in response to tetanus toxoid was not due to a toxic effect of 63Flu. Interestingly, other accessory functions, including the ability to support mitogen- and anti-CD3-mediated T-cell proliferation, remained intact. These data suggest that alteration of macrophage function relating to viral infection occurs at multiple levels and may contribute to the immunosuppression observed following influenza virus infection.

Antigen-Presenting Cells↗
PubMed1994

A genetic linkage map for cattle.

We report the most extensive physically anchored linkage map for cattle produced to date. Three-hundred thirteen genetic markers ordered in 30 linkage groups, anchored to 24 autosomal chromosomes (n = 29), the X and Y chromosomes, four unanchored syntenic groups and two unassigned linkage groups spanning 2464 cM of the bovine genome are summarized. The map also assigns 19 type I loci to specific chromosomes and/or syntenic groups and four cosmid clones containing informative microsatellites to chromosomes 13, 25 and 29 anchoring syntenic groups U11, U7 and U8, respectively. This map provides the skeletal framework prerequisite to development of a comprehensive genetic map for cattle and analysis of economic trait loci (ETL).

Animals↗
PubMed1994

Mechanosensitive modulation of myosin phosphorylation and phosphatidylinositol turnover in smooth muscle.

Myosin light chain phosphorylation and phosphatidylinositol turnover were measured at different muscle lengths in bovine tracheal smooth muscle. The relationship between myosin phosphorylation and muscle length was linear between optimal length (Lo) and 0.1 Lo in both unstimulated and carbachol-activated tissues. However, myosin phosphorylation in carbachol-activated tissues was more sensitive to changes in muscle length. As a result, suprabasal myosin phosphorylation induced by carbachol was significant at Lo but became insignificant at 0.1 Lo. Phosphatidylinositol turnover was assayed by measuring the formation of myo-[3H]inositol phosphates in unstimulated and carbachol-activated tissues using the Li+ method. Pairs of time-matched and length-matched muscle strips were used for control (unstimulated) and activation by carbachol. Phosphatidylinositol turnover in carbachol-activated tissues was more sensitive than that in unstimulated tissues to changing length. As a result, suprabasal phosphatidylinositol turnover induced by carbachol was significant at Lo but became insignificant at 0.1 Lo. These results indicated that myosin phosphorylation and phosphatidylinositol turnover mediated by muscarinic receptor activation were modulated by the mechanical state of smooth muscle.

Animals↗
PubMed1993

COOH-terminal amino acids of the alpha subunit play common and different roles in human choriogonadotropin and follitropin.

Human choriogonadotropin (hCG) and follitropin (FSH) belong to the glycoprotein hormone family. These hormones are heterodimers and composed of a common alpha subunit and a distinct beta subunit which confers receptor-binding specificities. In addition to this structural similarity, they share a similar signal pathway involving G protein, adenylyl-cyclase and induction of cAMP synthesis. Therefore, a presumptive relationship of these common structure and function has been the subject of extensive past investigations, but a definitive clue has been elusive. As a step to address this important issue, a series of recombinant mutants of hCG and human FSH were generated in which the COOH-terminal amino acids of the alpha subunit were successively removed or substituted. Furthermore, a set of peptides were synthesized with sequences corresponding to different regions of the alpha subunit. Deletion of the alpha COOH-terminal Ser92 had no effect on receptor-binding or cAMP induction by FSH and hCG. Truncation of alpha Lys91-Ser92 or alpha His90-Lys91-Ser92 abolished the ability of both hormones to induce cAMP synthesis. It significantly reduced receptor binding of FSH but not hCG. The different functions of the alpha COOH-terminal region are further noticed with a peptide corresponding to the last 10 amino acids of alpha. It failed to bind to the FSH receptor but was capable of binding to the LH/CG receptor and stimulating cAMP synthesis. These results are the first conclusive evidence that alpha His90-Lys91 play an essential role in cAMP induction of both hormones. In contrast to this common role, they are necessary for FSH binding to the FSH receptor but not for hCG binding to the LH/CG receptor. The hCG alpha COOH-terminal region makes direct contact with the LH/CG receptor, and this low affinity contact is necessary and sufficient to activate the receptor for signal generation. This conclusion is supported by the study using mutant hCGs in which either alpha His90 or Lys91 was substituted.

Amino Acid Sequence↗
PubMed1993

Interference screw fixation of cervical grafts. A combined in vitro biomechanical and in vivo animal study.

The dislodgement of an anterior bone graft in the cervical spine is a frequent complication of attempted fusion following discectomy or corpectomy. It has been hypothesized that fixation augmented with interference screws may increase the pullout strength of the construct and decrease the rate of these complications. In vitro mechanical tests and in vivo sheep studies were conducted to compare interference screw fixation methods for enhancing the fixation between the bone graft and the adjacent vertebra. Using human cadaver cervical spines, the anterior pullout strengths of cervical bone grafts were compared using fixation with and without the addition of interference screws for the in vitro mechanical testing. The mean pullout forces for a Smith-Robinson type bone graft alone was 58.1 N (SD 11.4 N); for the graft augmented with two 3.5 mm cancellous bone screws, 153.9 N (58.9 N); and for the graft with four 3.5 mm screws, 217.1 N (SD 69.9 N). The pullout strengths of the two- and four-3.5 mm screw constructs were significantly greater than the strength of the graft alone (P < 0.05). Similarly placed 2.7 mm cortical screws of the same length provided increased pullout strength (123.7 N 38.6 N and 142.5 N 38.2 N for two- and four-screw constructs, respectively); however, in comparison to the graft alone, these differences were not statistically significant. For both screw types, the four-screw fixations were stronger than the two-screw fixations, although these differences were not statistically significant. For the in vivo portion of the study, a single-level anterior cervical discectomy and fusion were performed on 20 sheep.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗