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Biomedical subjects

S N Kim

Publications and source records attributed to S N Kim.

At least 19 recordsLinked to original sources
PubMed2006

Abdominal aortic aneurysm repair in kidney transplant recipients.

Renal transplant recipients currently survive many years with a consequent increase in the risk of presentation with vascular diseases. So aortic reconstruction in transplant patients has been increasingly reported the most common procedures involving abdominal aorta aneurysms (AAAs). The most important problem during the operation is ischemic injury to the transplanted kidney during aortic clamping. Protection for the grafted kidney from ischemic or reperfusion injury may be achieved by permanent or temporary axillo-femoral, femoro-femoral, aorto-iliac bypass, cold perfusion, local cold preservation, or autotransplantation. Some authors have reported protection of the transplanted kidney function without any other procedures. We had experience with four AAA cases in kidney transplant patients, including two cases of direct reconstruction of the AAA without any other surgical protection, one autotransplantation, and one AAA excision with using temporary aortofemoral bypass with good results. Herein, we report two cases of successful AAA excision without a surgical procedure for graft protection.

Aorta, Abdominal↗
PubMed2005

Resonance Raman spectroscopy characterization of single-wall carbon nanotube separation by their metallicity and diameter.

Several techniques were recently reported for the bulk separation of metallic (M) and semiconducting (S) single wall carbon nanotubes (SWNTs), using optical absorption and resonance Raman spectroscopy (RRS) as a proof of the separation. In the present work, we develop a method for the quantitative evaluation of the M to S separation ratio, and also for the SWNT diameter selectivity of the separation process, based on RRS. The relative changes in the integrated intensities of the radial-breathing mode (RBM) features, with respect to the starting material, yield the diameter probability distribution functions for M and S SWNTs in the separated fractions, accounting for the different resonance conditions of individual SWNTs, while the diameter distribution of the starting material is obtained following the fitting procedure developed by Kuzmany and coworkers. Features other than the RBM are generally less effective for characterization of the separation process for SWNTs.

Metals↗
PubMed2001

8-Cl-cAMP induces cell cycle-specific apoptosis in human cancer cells.

8-Cl-cyclic adenosine monophosphate (8-Cl-cAMP) has been known to induce growth inhibition and differentiation in a variety of cancer cells by differential modulation of protein kinase A isozymes. To understand the anticancer activity of 8-Cl-cAMP further, we investigated the effect of 8-Cl-cAMP on apoptosis in human cancer cells. Most of the tested human cancer cells exhibited apoptosis upon treatment with 8-Cl-cAMP, albeit with different sensitivity. Among them, SH-SY5Y neuroblastoma cells and HL60 leukemic cells showed the most extensive apoptosis. The effect of 8-Cl-cAMP was not reproduced by other cAMP analogues or cAMP-elevating agents, showing that the effect of 8-Cl-cAMP was not caused by simple activation of protein kinase A (PKA). However, competition experiments showed that the binding of 8-Cl-cAMP to the cAMP receptor was essential for the induction of apoptosis. After the treatment of 8-Cl-cAMP, cells initially accumulated at the S and G2/M phases of the cell cycle and then apoptosis began to occur among the population of cells at the S/G2/M cell cycle phases, indicating that the 8-Cl-cAMP-induced apoptosis is closely related to cell cycle control. In support of this assumption, 8-Cl-cAMP-induced apoptosis was blocked by concomitant treatment with mimosine, which blocks the cell cycle at early S phase. Interestingly, 8-Cl-cAMP did not induce apoptosis in primary cultured normal cells and non-transformed cell lines, showing that 8-Cl-cAMP-induced apoptosis is specific to transformed cells. Taken together, our results show that the induction of apoptosis is one of the mechanisms through which 8-Cl-cAMP exerts anticancer activity.

3T3 Cells↗
PubMed2001

Molecular cloning and characterization of groESL operon in Streptococcus pneumoniae.

GroEL is a major target of the immune defense in infection and seems to be negatively regulated by HrcA in gram-positive organisms. However, HrcA's mechanism has not been elucidated. To elucidate the role of groEL in Streptococcus pneumoniae, the groESL operon was cloned in Escherichia coli. The promoter region of the pneumococcal groESL operon contained a sigmaA type promoter and an inverted repeat (CIRCE). A Northern blot analysis of the groESL operon demonstrated that the groESL operon is transcribed as a bicistronic mRNA, and reached maximum expression 7.5 to 10 min after heat shock. A primer extension analysis showed a potential transcription start point at 155 bp upstream of the translation start site, preceding the groES gene. The putative negative regulator of the groEL gene, hrcA, of S. pneumoniae was recovered by PCR-based chromosomal walking from grpE locus. A sequence analysis showed a sigmaA type promoter flanked by 2 CIRCE elements. His-tagged HrcA was overexpressed as a soluble form in E. coli and bound to the CIRCE regions in the promoter of both groESL and dnaK operons in vitro. Additionally, a helix-loop helix motif, a putative DNA binding domain, was found at the C-terminal of HrcA. These results will help to determine the nature of HrcA in the groESL repression.

Amino Acid Sequence↗
PubMed2001

Caspase-mediated Cdk2 activation is a critical step to execute transforming growth factor-beta1-induced apoptosis in human gastric cancer cells.

Although TGF-beta1, a growth inhibitor, is known to also induce apoptosis, the molecular mechanism of this apoptosis is largely undefined. Here, we identify the mechanism of TGF-beta1-induced apoptosis in SNU-16 human gastric cancer cells. Cell cycle and TUNEL analysis showed that, upon TGF-beta1 treatment, cells were initially arrested at the G1 phase and then driven into apoptosis. Of note, caspase-3 was activated in accordance with TGF-beta1-induced G1 arrest. Activated caspase-3 is targeted to cleave p21(cip1), p27(kip1), and Rb, which play important roles in TGF-beta-induced G1 arrest, into inactive fragments. Subsequently, Cdk2 was aberrantly activated due to the cleavage of p21 and p27. We found that the inhibition of Cdk2 activity efficiently blocks TGF-beta1-induced apoptosis, whereas it did not prevent caspase-3 activation or the subsequent cleavage of target proteins. In contrast, the suppression of caspase-3 activity inhibited the cleavage of target proteins, the activation of Cdk2, and the induction of apoptosis. Taken together, our results suggest that activation of caspase-3 by TGF-beta1 may initiate the conversion from G1 cell cycle arrest to apoptosis via the cleavage of p21, p27 and Rb, which in turn causes Cdk2 activation and, most significantly, Cdk2 activation as a downstream effector of caspase is a critical step for the execution of TGF-beta1-induced apoptosis.

Annexin A5↗
PubMed2001

Dicaffeoyl- or digalloyl pyrrolidine and furan derivatives as HIV integrase inhibitors.

Human immunodeficiency virus (HIV) integrase (IN) catalyzes the integration of HIV DNA copy into the host cell DNA. Such integration is essential for the production of progeny viruses, and therefore therapeutic agents that can inhibit this process should be effective anti-HIV agents. We have previously reported the inhibitory activity of dicaffeoylglucosides against HIV IN. In the present study, we have synthesized and tested dicaffeoyl or digalloyl compounds joined through a five-membered heterocyclic ring as HIV IN inhibitors to explore the SARs of this family of compounds. The starting heterocyclic diols were prepared from L-tartaric acid, diethyl L-tartarate or D-(+)-ribonic gamma-lactone. We found that the HIV IN inhibitory activities of dicaffeoyl derivatives were comparable to that of L-chicoric acid (IC(50)=24.9 microM). On the other hand, digalloyl derivatives were more potent than L-chicoric acid with IC(50) values of 4.7--15.6 microM.

Caffeic Acids↗
PubMed2001

Disseminated superficial actinic porokeratosis with both typical and prurigo nodularis-like lesions.

We report a 50-year-old Korean patient who developed a disseminated superficial actinic porokeratosis (DSAP) with two types of lesions. One was a typical DSAP lesion clinically and histopathologically. The other was clinically similar to prurigo nodularis, but histologic examination showed the findings of porokeratosis such as cornoid lamellae and loss of the granular layer in addition to those of chronic lichenified dermatitis, so it could be described as prurigo nodularis-like porokeratosis. The nodular lesions seemed to develop on preexisting typical lesions of DSAP mainly during the summer by the aggravation of pruritic symptoms and scratching associated with sun exposure. Although we could not find any published reports describing lesions like those of our case, we think that such prurigo nodularis-like porokeratosis can develop in patients with DSAP in some situations involving pruritus and scratching.

Diagnosis, Differential↗
PubMed2001

Antiepiligrin cicatricial pemphigoid with autoantibodies to the beta subunit of laminin 5 and associated with severe laryngeal involvement necessitating tracheostomy.

We report the case of a 67-year-old Korean woman with antiepiligrin cicatricial pemphigoid. The patient's serum immunoprecipitated polypeptides that comigrated with those identified in serum from a representative patient with antiepiligrin cicatricial pemphigoid, and was reactive with the laminin beta3-subunit on immunoblotting. She presented not only with cutaneous, oral and ocular, but also with laryngeal and esophageal involvement. Because the supraglottic stenosis was severe, she had to undergo tracheostomy to maintain airway patency.

Aged↗
PubMed2000

6-Hydroxy-1,3-dioxin-4-ones as non-peptidic HIV protease inhibitors.

HIV protease inhibitors containing 6-hydroxy-1,3-dioxin-4-one ring system as a new scaffold have been prepared. Among them, compound 4d showed potent HIV protease inhibitory activity (IC50 = 0.01 microM) and antiviral activity in cell culture (EC50 = 0.96 microM, SI = 65.69).

Anti-HIV Agents↗
PubMed2000

Synthesis and HIV-1 integrase inhibitory activities of caffeoylglucosides.

Caffeoylglucosides, which have a glucose ring as a central linker, were synthesized from methyl D-glucosides, and their anti-HIV-1 activities were tested. Among them, four dicaffeoylglucosides (IC50 = 29.1+/-35.1 microM), 6a, 6b, 9b and 10b, showed HIV-1 integrase inhibitory activity as potent as L-chicoric acid.

Anti-HIV Agents↗
PubMed2000

Dual anticancer activity of 8-Cl-cAMP: inhibition of cell proliferation and induction of apoptotic cell death.

8-Cl-cAMP induces apoptotic cell death in human cancer cells. To look at this more closely, we examined the changes in the levels of Bcl-2 family proteins during 8-Cl-cAMP-induced apoptosis of SH-SY5Y human neuroblastoma cells. Following the treatment with 8-Cl-cAMP, Bcl-2 was transiently down-regulated and Bad was increased continuously up to day 5. In addition, overexpression of Bcl-2 efficiently blocked the 8-Cl-cAMP-induced apoptosis, suggesting Bcl-2 family proteins may be involved in the 8-Cl-cAMP-induced apoptosis. The contribution of the apoptotic cell death and the inhibition of cell proliferation in the 8-Cl-cAMP-induced growth inhibition was closely monitored in the Bcl-2-overexpressing cells. Though the apoptosis was reduced significantly, no significant difference was observed in the inhibition of cell proliferation up to day 2 of 8-Cl-cAMP treatment. These results suggest that 8-Cl-cAMP exerts anticancer activity by two distinct mechanisms, i.e. , through the inhibition of cell proliferation as well as the induction of apoptosis. Supporting this notion was the observations that (1) suppression of apoptosis by zVAD did not abrogate 8-Cl-cAMP-induced inhibition of cell proliferation, and (2) 8-Cl-cAMP did not show additive inhibition of cell proliferation in RIIbeta-overexpressing cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2000

Participation of type II protein kinase A in the retinoic acid-induced growth inhibition of SH-SY5Y human neuroblastoma cells.

To examine the role of protein kinase A (EC 2.7.1.37) isozymes in the retinoic acid-induced growth inhibition and neuronal differentiation, we investigated the changes of protein kinase A isozyme patterns in retinoic acid-treated SH-SY5Y human neuroblastoma cells. Retinoic acid induced growth inhibition and neuronal differentiation of SH-SY5Y cells in a dose- and time-dependent manner. Neuronal differentiation was evidenced by extensive neurite outgrowth, decrease of N-Myc oncoprotein, and increase of GAP-43 mRNA. Type II protein kinase A activity increased by 1.5-fold in differentiated SH-SY5Y cells by retinoic acid treatment. The increase of type II protein kinase A was due to the increase of RIIbeta and Calpha subunits. Since type II protein kinase A and RIIbeta have been known to play important role(s) in the growth inhibition and differentiation of cancer cells, we further investigated the role of the increased type II protein kinase A by overexpressing RIIbeta in SH-SY5Y cells. The growth of RIIbeta-overexpressing cells was slower than that of parental cells, being comparable to that of retinoic acid-treated cells. Retinoic acid treatment further increased the RIIbeta level and further inhibited the growth of RIIbeta-overexpressing cells, showing strong correlation between the level of RIIbeta and growth inhibition. However, RIIbeta-overexpressing cells did not show any sign of neuronal differentiation and responded to retinoic acid in the same way as parental cells. These data suggest that protein kinase A participates in the retinoic acid-induced growth inhibition through the up-regulation of RIIbeta/type II protein kinase A.

Antineoplastic Agents↗
PubMed2000

Concurrent chemotherapy and radiotherapy in invasive cervical cancer patients with high risk factors.

The aim of this study was to evaluate the survival of 395 previously untreated cervical cancer patients with at least one high risk factor following concurrent chemoradiation and to assess the toxicities. Two different chemotherapy regimens were used for concurrent chemoradiation. In the patients with squamous cell carcinoma, 100 mg/m2 of cisplatin was infused intravenously, followed immediately by five consecutive daily administrations of 5-fluorouracil, 1,000 mg/m2/day, each infused intravenously over 24 hr. As for the patients with adenocarcinoma, 70 mg/m2 of cisplatin, 250 mg/m2 of cytoxan and 45 mg/m2 of adriamycin were administered intravenously on days 1, 2, and 3, respectively. The 5-year survival rate was 54.4% with stage III and IV, 62.6% with lymph node metastasis on computed tomogram or MRI, 77.9% with stage I-II disease with lesion size > or =4 cm, and 50.3% with small cell carcinoma or adenocarcinoma. Side effects from concurrent chemoradiation such as nausea, vomiting, and alopecia were present in all 395 cases. Anemia, leukopenia, thrombocytopenia, hepatotoxicity, and nephrotoxicity were observed to varying degrees, but there was no toxic death. This study suggests that cisplatin-based concurrent chemoradiation in treating cervical cancer patients with high risk factors is effective and relatively well tolerated, with acceptable toxicity.

Adenocarcinoma↗
PubMed2000

Characterization of epidermal growth factor receptor function in lysophosphatidic acid signaling in PC12 cells.

Lysophosphatidic acid (LPA) is a lipid metabolite that induces the activation of mitogen-activated protein kinase (MAPK) through binding to the G protein-coupled receptor in a number of cell lines and cultures. Recent studies have revealed that LPA is able to rapidly induce the phosphorylation of MAPK through an epidermal growth factor (EGF) receptor-dependent pathway. We investigated the role of the EGF receptor in the signaling pathway initiated by LPA stimulation in nerve growth factor (NGF)-responsive PC12 cells well known to transiently retract their own neurites upon LPA stimulation. LPA-stimulated MAPK signaling was suppressed by the selective EGF receptor inhibitor and in the dominant negative mutant EGF receptor cell line. As in the EGF signaling pathway, the complex of EGF receptor with adapter proteins Shc and Sos was formed in response to LPA stimulation, suggesting there is an intracellular mechanism for transactivation. A neurite retraction assay was also performed to examine the role of the EGF receptor in PC12 cell differentiation, which related to the involvement of LPA-induced neurite retraction. These results suggest that the receptor tyrosine kinase can be activated in a ligand-independent manner through intracellular crosstalk between the signaling pathways.

Animals↗
PubMed1999

Identification of the polyamine induced proteins in Escherichia coli.

The polyamine (PA)-induced proteins were identified by SDS-PAGE, and by two dimensional gel analysis in Escherichia coli strains. A large number of the PA-induced proteins were acidic. The molecular weights of the most highly induced proteins were 40 and 82 kDa proteins in the wild type and PA-auxotrophic mutant, respectively. Although a part of the PA-induced proteins were induced both in the wild type and PA auxotrophic mutant, most of them seem to be induced either in the wild type or mutant. These features may provide a foundation for evaluating the role of the PA-induced proteins relative to the physiology and environmental stress of Escherichia coli.

Bacterial Proteins↗
PubMed1999

Ala99ser mutation in RI alpha regulatory subunit of protein kinase A causes reduced kinase activation by cAMP and arrest of hormone-dependent breast cancer cell growth.

Expression of the RIalpha regulatory subunit of protein kinase A type I is increased in human cancer cell lines, in primary tumors, in cells after transformation, and in cells upon stimulation of growth. Ala99 (the pseudophosphorylation site) of human RIalpha was replaced with Ser (RIalpha-p) for the structure-function analysis of RIalpha. MCF-7 hormone-dependent breast cancer cells were transfected with an expression vector for the wild-type RIalpha or mutant RIalpha-p. Overexpression of RIalpha-P resulted in suppression of protein kinase A type II, the isozyme of type I kinase, production of kinase exhibiting reduced cAMP activation, and inhibition of cell growth showing an increase in G0/G1 phase of the cell cycle and apoptosis. The wild-type RIalpha overexpression had no effect on protein kinase A isozyme distribution or cell growth. Overexpression of protein kinase A type II regulatory subunit, RIIbeta, suppressed RIalpha and protein kinase A type I and inhibited cell growth. These results show that the growth of hormone-dependent breast cancer cells is dependent on the functional protein kinase A type I.

Alanine↗