Biomedical subjects

M C Kim

Publications and source records attributed to M C Kim.

At least 37 records · Page 2Linked to original sources

PubMed1999

Involvement of specific calmodulin isoforms in salicylic acid-independent activation of plant disease resistance responses.

The Ca2+ signal is essential for the activation of plant defense responses, but downstream components of the signaling pathway are still poorly defined. Here we demonstrate that specific calmodulin (CaM) isoforms are activated by infection or pathogen-derived elicitors and participate in Ca2+-mediated induction of plant disease resistance responses. Soybean CaM (SCaM)-4 and SCaM-5 genes, which encode for divergent CaM isoforms, were induced within 30 min by a fungal elicitor or pathogen, whereas other SCaM genes encoding highly conserved CaM isoforms did not show such response. This pathogen-triggered induction of these genes specifically depended on the increase of intracellular Ca2+ level. Constitutive expression of SCaM-4 and SCaM-5 in transgenic tobacco plants triggered spontaneous induction of lesions and induces an array of systemic acquired resistance (SAR)-associated genes. Surprisingly, these transgenic plants have normal levels of endogenous salicylic acid (SA). Furthermore, coexpression of nahG gene did not block the induction of SAR-associated genes in these transgenic plants, indicating that SA is not involved in the SAR gene induction mediated by SCaM-4 or SCaM-5. The transgenic plants exhibit enhanced resistance to a wide spectrum of virulent and avirulent pathogens, including bacteria, fungi, and virus. These results suggest that specific CaM isoforms are components of a SA-independent signal transduction chain leading to disease resistance.

Calcium↗

PubMed1998

Up-regulation of the expression of major histocompatibility complex class I antigens by plasmid DNA transfection in non-hematopoietic cells.

The effect of DNA on the surface expression of major histocompatibility (MHC) class I antigens was examined in non-hematopoietic tumor cell lines. Transfection with plasmid DNA via liposome or electroporation significantly increased the surface expression of MHC class I molecules in a transient manner. Northern blot analysis showed that levels of MHC class I mRNA were increased by DNA transfection, probably via transcriptional activation. In contrast, the expression of the MHC class II and beta-actin genes was not affected, suggesting that the up-regulation of MHC class I expression by plasmid DNA works in a gene-specific manner.

Actins↗

PubMed1998

Clinical results of 24 pituitary macroadenomas with linac-based stereotactic radiosurgery.

PURPOSE: To determine the impact of stereotactic radiosurgery (SRS) on the clinical course, hormonal status, and follow-up CT/MRI scan of pituitary macroadenomas. METHODS AND MATERIALS: From July 1988 to March 1996, 24 pituitary macroadenomas had been treated using 6 MV linear accelerator based SRS. They consisted of 11 (45.8%) prolactinomas, 2 (8.3%) growth hormone (GH)-secreting tumors, 1 (4.2%) Cushing's disease, 8 (33.3%) nonsecreting (nonfunctioning: NF) tumors, and 2 (8.3%) mixed prolactin-growth hormone (PRL-GH)-secreting tumors (M:F = 12:12; aged 21-61 years). Postoperative irradiation was performed in all cases except for the instance of Cushing's disease. The prescribed dose to tumor center varied from 10 to 27 Gy (mean 21.1 Gy) using a collimator size of 0.5 to 2.5 cm. The follow-up duration ranged from 13 to 89 months (mean 49.2 months). Results from these patients were compared to our results using conventional radiation. RESULTS: Visual acuity and field defect were improved or became normal in 19 (79.2%) cases. Four (16.7%) remained unchanged after the treatment. One (4.1%) progressed 6 years after SRS and subsequently had repeat surgery with conventional boost irradiation. Of the 13 (46.4%) prolactinomas, including two mixed PRL-GH secreting tumors, 11 (84.1%) revealed normal hormonal levels within 1 year after SRS. In contrast, it took 2 years to become normal after conventional radiation therapy. In four GH-secreting tumors including two mixed PRL-GH secreting tumors, SRS and conventional methods showed similar responses. On follow-up imagings of the 21 patients, the mass was completely resolved in 4 (16.7%), including 3 PRLs and one NF, decreased in 11 (45.8%), and unchanged in 5 (16.7%) with central necrosis or cysts. One (4.2%) progressed and was reoperated 6 years after treatment. The complications related to SRS were comparable to those from conventional method. CONCLUSION: Radiosurgery can be used effectively in patients with pituitary adenoma. In this study, a more rapid hormonal and clinical response was achieved with radiosurgery than with conventional pituitary irradiation treatment.

Adenoma↗

PubMed1998

Effects of systemic hypothermia and selective brain cooling on ischemic brain damage and swelling.

The present study investigates the neuroprotective effects of temporary mild systemic hypothermia and selective brain cooling against focal cerebral infarction in the rat and the changes of cortical blood flow, and compares these two treatment modalities. In permanent middle cerebral artery (MCA) model, the treatments were induced 15 min following the artery occlusion. The animals were kept at the desired rectal or brain temperature (about 32 degrees C) for 30 min; (each, n = 6) and for 1 hr (each, n = 6), and then allowed to rewarm spontaneously, whereas control animals were kept at normothermia throughout the experiment. The volumes of brain infarction and edema were assessed 24 hr post-occlusion. The blood flow of the dorsolateral cortex was monitored by Laser-Doppler flowmetry (LDF) in the other experiments. Hemispheric infarct volume was attenuated only in the animals treated for 1 hr with systemic hypothermia (49.2%, P < 0.001) and selective brain cooling (26.7%, P < 0.01). The volume of brain swelling was diminished only in the animals treated with systemic hypothermia for 1 hr (23.6%, P < 0.05). LDF examination revealed a sharp drop in blood flow upon MCA occlusion and maintaining in low blood flow throughout the experiment in the control and systemic hypothermia. However, in the selective brain cooling, the reduced blood flow increased from 40% to 70% of baseline value while the brain was rewarmed. The present study indicates that mild systemic hypothermia has much stronger protective effects against focal cerebral infarction and edema than selective brain cooling. The lack of protective effects of selective brain cooling may be caused by post-cooling cerebral hyperemia in the ischemia area.

Animals↗

PubMed1998

Neuronal laterality in Parkinson's disease with unilateral symptom by in vivo 1H magnetic resonance spectroscopy.

RATIONALE AND OBJECTIVES: The authors investigate whether there is a lateral effect of 1H-magnetic resonance spectroscopy (MRS) observable metabolite ratios between the symptomatic and the asymptomatic side in Parkinson's disease with unilateral symptoms. METHODS: Localized in vivo 1H MRS was used to measure the metabolite levels in the symptomatic and the asymptomatic sides of the substantia nigra (SN) and putamen-globus pallidus (PG) in Parkinson's disease with unilateral symptom (n = 15). The metabolite ratios of N-acetylasparatate (NAA)/creatine (Cr), and choline-containing compounds (Cho)/Cr in the symptomatic side were compared with those in the asymptomatic side. According to the symptomatic duration, the authors evaluated whether there was a specific correlation between laterality and the clinical stage. RESULTS: Significant metabolic lateral effect of NAA/Cr ratio was established between the symptomatic and the asymptomatic sides of SN and PG in Parkinson's disease with unilateral symptoms (P = 0.03). The decreased NAA/Cr ratio was calculated in at least one of the selected regions in SN and PG, indicating neuronal loss. The main observations were that NAA/Cr ratios were reduced in the left symptomatic side (n = 7; P = 0.001) and reduced to a lesser degree in the right symptomatic side (n = 8; P = 0.03 [PG], P = 0.21 [SN]) and that there was no significant laterality of other metabolite ratios. CONCLUSIONS: On the basis of NAA/Cr ratios between the symptomatic and the asymptomatic sides, the present 1H MRS study shows a significant neuronal laterality in Parkinson's disease with unilateral symptoms. In vivo 1H MRS may provide a diagnostic marker for neuronal dysfunction in Parkinson's disease with unilateral symptoms.

Adult↗

PubMed1997

Compatibility of remifentanil hydrochloride with selected drugs during simulated Y-site administration.

The compatibility of remifentanil hydrochloride with 90 other drugs during simulated Y-site administration was studied. Five milliliters of remifentanil 25 and 250 micrograms/mL (as hydrochloride) in 0.9% sodium chloride injection or 5% dextrose injection was combined with 5 mL of each of 90 other drugs in 5% dextrose injection of 0.9% sodium chloride injection. Each combination was prepared in duplicate. The combinations were stored at approximately 23 degrees C under fluorescent light and examined with the unaided eye and in high-intensity monodirectional light during the first 15 minutes after preparation and at one and four hours. The turbidity of each combination was measured as well. Particle sizing and counting were performed for selected combinations. Most of the combinations exhibited no haze, turbidity, or color change throughout the study period. Remifentanil 25 micrograms/mL combined with chlorpromazine hydrochloride showed a small increase in haze within four hours. One of the combinations of remifentanil 250 micrograms/mL with cefoperazone sodium was unacceptably hazy within one hour. The combination of remifentanil 250 micrograms/mL with amphotericin B formed a gross precipitate upon mixing. Remifentanil 25 and 250 microgram/mL (as hydrochloride) in 0.9% sodium chloride injection was compatible for four hours at approximately 23 degrees C with all the drugs studied except chlorpromazine hydrochloride (with remifentanil 25 micrograms/mL), cefoperazone sodium (with remifentanil 250 micrograms/mL), and amphotericin B (with remifentanil 250 micrograms/mL in 5% dextrose injection).

Amphotericin B↗

PubMed1997

Differential activation of NAD kinase by plant calmodulin isoforms. The critical role of domain I.

NAD kinase is a Ca2+/calmodulin (CaM)-dependent enzyme capable of converting cellular NAD to NADP. The enzyme purified from pea seedlings can be activated by highly conserved soybean CaM, SCaM-1, but not by the divergent soybean CaM isoform, SCaM-4 (Lee, S. H., Kim, J. C., Lee, M. S., Heo, W. D., Seo, H. Y., Yoon, H. W., Hong, J. C., Lee, S. Y., Bahk, J. D., Hwang, I., and Cho, M. J. (1995) J. Biol. Chem. 270, 21806-21812). To determine which domains were responsible for this differential activation of NAD kinase, a series of chimeric SCaMs were generated by exchanging functional domains between SCaM-4 and SCaM-1. SCaM-4111, a chimeric SCaM-1 that contains the first domain of SCaM-4, was severely impaired (only 40% of maximal) in its ability to activate NAD kinase. SCaM-1444, a chimeric SCaM-4 that contains the first domain of SCaM-1 exhibited nearly full ( approximately 70%) activation of NAD kinase. Only chimeras containing domain I of SCaM-1 produced greater than half-maximal activation of NAD kinase. To define the amino acid residue(s) in domain I that were responsible for this differential activation, seven single residue substitution mutants of SCaM-1 were generated and tested for NAD kinase activation. Among these mutants, only K30E and G40D showed greatly reduced NAD kinase activation. Also a double residue substitution mutant, K30E/G40D, containing these two mutations in combination was severely impaired in its NAD kinase-activating potential, reaching only 20% of maximal activation. Furthermore, a triple mutation, K30E/M36I/G40D, completely abolished NAD kinase activation. Thus, our data suggest that domain I of CaM plays a key role in the differential activation of NAD kinase exhibited by SCaM-1 and SCaM-4. Further, the residues Lys30 and Glu40 of SCaM-1 are critical for this function.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1997

Colonization rates and serotypes of group B streptococci isolated from pregnant women in a Korean tertiary hospital.

In a study designed to provide data on the rates of maternal carriage of group B streptococci (GBS) in Korean women, vaginal, anorectal, and urethral swab specimens from 459 pregnant women and ear canal and umbilicus swabs from their 288 neonates were cultured with new Granada medium and selective Todd-Hewitt broth. Additionally, the serotypes of 64 isolates of GBS and the minimal inhibitory concentrations of seven antimicrobial agents for these isolates were determined. The rate of colonization by GBS in pregnant women and in their babies was 5.9% (27/459) and 0.7% (2/288), respectively. The rates of resistance of GBS isolated from pregnant women were 13.3% to clindamycin, 5% to erythromycin, and 98.3% to tetracycline. The majority of GBS isolates from pregnant women belonged to serotypes Ib (48.3%), Ia (24.1%), and III (20.7%).

Adolescent↗

PubMed1997

Differential expression of two functional serine/threonine protein kinases from soybean that have an unusual acidic domain at the carboxy terminus.

Two soybean cDNA clones, SPK-3 and SPK-4, encoding putative protein kinases were isolated and characterized. Both cDNAs encoded approximately 40-kDa serine/threonine kinases with unusual stretches of acidic amino acids in their carboxy-terminal regions, which are highly homologous to PKABA1 from wheat and ASKs from Arabidopsis. These kinases are encoded by one- or two-copy genes in the soybean genome. Notably, SPK-3 and -4 showed different patterns of expression in various soybean tissues. SPK-3 is highly expressed in dividing and elongating tissues of young seedlings but relatively weakly in tissues of mature plants. In contrast, SPK-4 showed relatively high and constitutive expression in all the tissues examined except for leaf tissues of mature plants. Although various stressors, such as dehydration and high salinity, increased the expression of both genes, the induction kinetics were different. The two genes also differed in their response to abscisic acid (ABA). SPK-3 was induced but SPK-4 was not affected by exogenously supplied abscisic acid. In accordance with these expression data analysis of the activity of a chimeric SPK-3 promoter::beta-glucuronidase (GUS) reporter gene by transient expression in tobacco leaves confirmed the inducibility of SPK-3 by salt and ABA. Polyclonal antibodies raised against a recombinant SPK-4 protein produced in Escherichia coli specifically recognized both recombinant SPK-3 and -4 proteins. Kinase assays using affinity-purified SPK-4/ antibody complexes with crude soybean extracts as substrate identified specific phosphorylation of two 41 and 170 kDa soybean proteins that were phosphorylated on serine residues. Taken together, our results suggest that SPK-3, and/or SPK-4 are functional serine protein kinase(s). Furthermore, SPK-3 and -4 may play different roles in the transduction of various environmental stresses.

Amino Acid Sequence↗

PubMed1996

Computer-aided design optimization with the use of a fast dose model for linear-accelerator-based stereotactic radiosurgery.

In order to efficiently plan non-spherical radiosurgical targets we have used computer-aided design optimization techniques with a fast dose model. A study of the spatial dose distribution for single or multiple non-coplanar arcs was carried out using a 18 cm diameter spherical head model. The dose distribution generated from the 3D dose computation algorithm can be represented by a simple analytic form. Two analytic dose models were developed to represent the dose for preset multiple non-coplanar arcs or a single arc: spherical and cylindrical. The spherical and cylindrical dose models compute dose quickly for each isocentre and single arc. Our approach then utilizes a computer-aided design optimization (CAD) with the use of two fast approximate dose models to determine the positions of isocentres and arcs. The implementation of CAD with fast dose models was demonstrated. While the fast dose models are only approximations of the true dose distribution, it is shown that this approximate model is sufficient to optimize isocentric position, collimator size and arc positions with CAD.

Computer-Aided Design↗

PubMed1995

Molecular cloning and functional characterization of a cDNA encoding nucleosome assembly protein 1 (NAP-1) from soybean.

NAP-1, a protein first isolated from mammalian cells, can introduce supercoils into relaxed circular DNA in the presence of purified core histones. Based on its in vitro activity, it has been suggested that NAP-1 may be involved in nucleosome assembly in vivo. We isolated a cDNA clone encoding a soybean NAP-1 homolog, SNAP-1. The SNAP-1 cDNA contains an open reading frame of 358 amino acids residues with a calculated molecular weight of 41 kDa. The deduced amino acid sequence of SNAP-1 shares sequence similarity with yeast NAP-1 (38%) and human hNRP (32%). Notable features of the deduced sequence are two extended acidic regions thought to be involved in histone binding. SNAP-1 expressed in Escherichia coli induces supercoiling in relaxed circular DNA, suggesting that SNAP-1 may have nucleosome assembly activity. The specific activity of SNAP-1 is comparable to that of HeLa NAP-1 in an in vitro assay. Western analysis reveals that SNAP-1 is expressed in the immature and young tissues that were examined, while mature tissues such as old leaves and roots, show very little or no expression. NAP-1 homologs also appear to be present in other plant species.

Amino Acid Sequence↗

PubMed1995

Immunohistochemical studies on melanin associated antigen (MAA) induced experimental autoimmune anterior uveitis (EAAU).

Experimental autoimmune anterior uveitis (EAAU), a model of uveitis induced by sensitization to melanin associated antigen (MAA) derived from the iris and ciliary body, closely resembles human acute anterior uveitis. The immunopathogenesis of EAAU was studied by immunohistochemical detection of immune cells and the expression of Ia, ICAM-1 and LFA-1 antigens. Male Lewis rats were immunized with bovine MAA, mixed with CFA and pertussis toxin in the hind foot pad. Animals were examined daily by slit-lamp biomicroscopy and serially sacrificed up to 30 days. Immunohistology of the enucleated eyes was performed with monoclonal antibodies W3/25 (CD4), OX-8 (CD8), ED2 (macrophage), OX-33 (B cell), OX-6 (Ia), IA29 (ICAM-1) and WT.1 (LFA-1). During each stage of EAAU, CD4+ T cells predominated over both CD8+ T cells and macrophages in the uvea. Very few B cells were detected during each stage of EAAU. EAAU could not be induced by the adoptive transfer of sera obtained from immunized animals. Low levels of constitutive ICAM-1 and Ia were observed. An increase in ICAM-1 expression was first noted on the epithelial cells of the uveal tract and RPE on day 9 post immunization and preceded LFA-1 and Ia upregulation by approximately 2 days. The immunopathogenesis of EAAU appears to be linked to the presence of the CD4+ T cells.

Animals↗

PubMed1995

Experimental autoimmune anterior uveitis. Induction with melanin-associated antigen from the iris and ciliary body.

PURPOSE: This study was designed to investigate an animal model of uveitis that resembles anterior uveitis in humans after immunization with iris-ciliary body antigen. METHODS: Male Lewis rats 6 to 8 weeks of age were immunized with the buffer- and detergent-insoluble bovine iris-ciliary body antigen mixed with complete Freund's adjuvant and pertussis toxin. Antigen was digested with various proteolytic enzymes and tested in different rodent strains for a uveitogenic response. RESULTS: Acute iridocyclitis developed in both eyes of the Lewis rat during the second week after immunization, and the pattern of inflammation was similar to acute anterior uveitis in humans, with sudden onset, localization to the anterior uvea, and spontaneous resolution. Among the strains tested, F344 rats were susceptible to experimental autoimmune anterior uveitis but Long-Evans rats were not. Experimental autoimmune anterior uveitis did not develop in any of the mice studied, nor was it induced by immunization with synthetic melanin, amelanotic bovine tissues, pigmented bovine skin, or pigmented rat and rabbit iris-ciliary body. A soluble fraction derived from bovine melanin-associated antigen (BMAA) after digestion with the proteolytic enzyme V8 protease resulted in a disease similar to that observed with intact BMAA. CONCLUSIONS: A model of anterior uveitis has been induced in the Lewis rat after immunization with bovine uveal antigen, and it resembles the acute iridocyclitis observed in humans. These results suggest that the pathogenic antigen is a melanin-associated protein(s) present within the iris-ciliary body.

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

Spontaneous evolution of posttraumatic subdural hygroma into chronic subdural haematoma.

Thirteen of 145 patients with post-traumatic subdural hygroma (SDHy) developed chronic subdural haematoma (CSDH) at the involved site over a period of 6 years. CSDHs were found at the site of SDHys with no history of further head injury at a mean interval of 56 days. It appeared that these 13 patients did not have any distinguishing clinical features early on. Old age and brain atrophy on CT scans do not seem to be reasonable causative factors in the evolution of SDHy into CSDH. Initial enlargement of subdural accumulations at an early stage of SDHy and a subsequent increase in density at a later stage may point to the development of CSDH from SDHy in some instances. Ten of these 13 CSDH cases underwent surgical drainage, and the remaining 3 cases received no specific management. All resolved completely. The prognosis was good in all patients. The possible mechanism for the evolution of SDHy into CSDH is discussed.

Adult↗

PubMed1991

Fertilization and culture of rabbit oocytes in hydrogel chambers implanted in the peritoneal cavity of mouse recipients.

The purpose of this study was to determine whether in vivo fertilization and culture using a hydrogel chamber was possible. Hydrogel chambers were made from the mixture of low-acid hema, as a monomer, and tetraethylene glycol dimethacrylate (TGD) and ethylene glycol (EG), as the cross-linkers. Rabbit oocytes and spermatozoa were transferred into the lumen of the hydrogel chambers which were filled with chemically-defined culture medium containing no protein. The chambers containing the rabbit oocytes and spermatozoa were implanted within the mouse peritoneal cavity, and were examined after recovery from the chambers following 84 hours of preservation. A total of 88 oocytes preserved after 84 hours in pHema hydrogel chambers implanted in the peritoneal cavity of female mice resulted in 29 morulae and 46 blastocysts. Thus, demonstrating that fertilization and culture can occur inside of the hydrogel chamber.

Journal Article↗

PubMed1990

Ubiquinol-10 is an effective lipid-soluble antioxidant at physiological concentrations.

It is well known that ubiquinone-10 (coenzyme Q10, ubiquinone 50) acts as an electron carrier of the respiratory chain in mitochondria. In this paper we show that ubiquinol-10, the reduced form of ubiquinone-10, also efficiently scavenges free radicals generated chemically within liposomal membranes. Ubiquinol-10 is about as effective in preventing peroxidative damage to lipids as alpha-tocopherol, which is considered the best lipid-soluble antioxidant in humans. The number of radicals scavenged by each molecule of ubiquinol-10 is 1.1 under our experimental conditions. In contrast to alpha-tocopherol, ubiquinol-10 is not recycled by ascorbate. However, it is known that ubiquinol-10 can be recycled by electron transport carriers present in various biomembranes and possibly by some enzymes. We also show that ubiquinol-10 spares alpha-tocopherol when both antioxidants are present in the same liposomal membranes and that ubiquinol-10, like alpha-tocopherol, does not interact with reduced glutathione. Our data together with previous work on the antioxidant function of ubiquinol reported in the literature strongly suggest that ubiquinol-10 is an important physiological lipid-soluble antioxidant.

Kinetics↗

PubMed1990

Toxic acute renal failure and hepatitis after ingestion of raw carp bile.

The raw carp bile has both nephrotoxic and hepatotoxic effects which are not well known. Recently, we studied 13 patients who had toxic acute renal failure and toxic hepatitis after ingestion of raw bile of carp in 3, grass carp in 8 and silver carp in 2 cases. The purpose of this report is to alert physicians to this very rare cause of toxic acute renal failure and hepatitis. All patients presented initially with gastrointestinal upset after eating. These symptoms were followed by oliguria in 7 patients (54%), hematuria was noted in 10 (77%) and jaundice in 8 patients (62%). Elevation of blood urea nitrogen, creatinine and transaminases lasted for about 3 weeks. The severity of the symptoms depended on the amount of bile ingested. All the patients recovered with conservative therapy and hemodialysis. Biopsy of the kidney revealed findings compatible with acute tubular necrosis similar to that produced by other nephrotoxins. Biopsy of the liver revealed findings consistent with acute toxic hepatitis. Both suggest toxic effects of carp bile as a cause of toxic acute renal failure and hepatitis.

Acute Kidney Injury↗