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Biomedical subjects

M Kim

Publications and source records attributed to M Kim.

At least 253 records · Page 14Linked to original sources
PubMed1997

Identification and expression of uvi31+, a UV-inducible gene from Schizosaccharomyces pombe.

The Schizosaccharomyces pombe uvi31+ gene has been previously isolated as a UV-inducible gene [Lee JK et al. (1994) Biochem Biophys Res Commun 202:1113-1119]. This gene encodes a protein of about 12 kDa with 57% amino acid sequence similarity to Escherichia coli BolA protein which is known to be involved in switching between the cell elongation and septation systems during the cell division cycle. The putative Mlul cell cycle box (MCB), SWI4/6-dependent cell cycle box (SCB), and gear-box elements are found in the upstream region of uvi31+ gene, suggesting that this gene shows the cell cycle-regulated and growth phase-dependent expression. Interestingly, the level of uvi31+ transcript varies throughout the cell cycle, peaking in G1 phase before septation, and also shows the growth phase-dependent pattern during cellular growth, increasing maximally at the diauxic shift phase just before stationary phase. Furthermore, the transcript level of this gene is raised after S phase arrest, and is also increased maximally at 4 hr after UV irradiation of 240 J/m2. These results suggest that the delayed induction of uvi31+ gene after UV irradiation may be caused by cell cycle control of this gene after DNA replication checkpoint arrest. Thus, the uvi31+ gene may play a role in controlling the progress of the cell cycle after DNA damage (UV irradiation).

Amino Acid Sequence↗
PubMed1997

Spin Echoes after Arbitrary N Pulses

Based on the Bloch equations, the general response of a nuclear spin-½ system to multiple RF pulses with arbitrary phases and flip angles is presented. The general solution is expressed in a form including the pathway vectors specifying the magnetization paths generated by a string of pulses. The pathway vectors are useful for predicting the exact positions, magnitudes, and number of echoes. Also, these vectors make it easy to trace the physical origin of an echo formation. It is shown that the maximum number of echoes after N pulses is (3N-1 - 1)/2 using this concept.

Journal Article↗
PubMed1997

A solenoid-like coil producing transverse RF fields for MR imaging.

A solenoidal RF coil is presented that generates an RF field only perpendicular to the long axis, so that it can be used longitudinally in the usual superconducting solenoid magnet for NMR. This new design is superior to the traditional saddle coil or Helmholtz pair. Applications for the coil will include imaging of legs, arms, etc., as well as analytical application in high-resolution NMR. A tilted single-turn-solenoid, which has the plane of each loop tilted with respect to the cylinder axis, is implemented to generate an RF field with a component perpendicular to the coil-cylinder axis. The novel addition of an eddy-current coil eliminates the undesirable longitudinal component of the RF field, leaving an RF field entirely perpendicular to the coil-cylinder axis. By inserting the eddy coil, the spatial homogeneity of the transverse RF field is greatly improved, with significant increases in the H1 field strength and receiving sensitivity. Images with the eddy-coil-modified tilted solenoid are remarkably uniform in intensity over a large useful volume.

Hand↗
PubMed1997

Discoid lupus erythematosus presenting as asymmetric posterior blepharitis.

PURPOSE: To describe the ophthalmic findings of patients with discoid lupus erythematosus. METHOD: We describe two women who originally were thought to have asymmetric posterior blepharitis; however, the involved eyelid also had an erythematous, scaly cutaneous lesion. RESULT: In both patients, histology and immunofluorescence studies performed on cutaneous biopsy specimens established the diagnosis of discoid lupus erythematosus. CONCLUSIONS: It is important to diagnose discoid lupus of the eyelids because misdiagnosis can delay treatment and thus lead to deformities of the eyelid margin. Misdiagnosis can also lead to a complicated full-thickness eyelid biopsy and delay the diagnosis of systemic lupus erythematosus.

Adult↗
PubMed1997

An intracellular anti-erbB-2 single-chain antibody is specifically cytotoxic to human breast carcinoma cells overexpressing erbB-2.

We previously demonstrated that delivery of a gene encoding an anti-erbB-2 intracellular single-chain antibody (sFv) resulted in down-regulation of cell surface erbB-2 levels and induction of apoptosis in erbB-2 overexpressing ovarian cancer cells. Based upon these findings, we hypothesized that human breast carcinomas overexpressing erbB-2 would be similarly affected by this genetic intervention. We evaluated the phenotypic effects resulting from intracellular expression of the anti-erbB-2 sFv on the human breast cancer cell lines MDA-MB-361, SK-BR-3, BT-474, MCF-7 and MDA-MB-231. Recombinant adenoviruses encoding either a reporter gene (AdCMVLacZ) or the endoplasmic reticulum (ER) directed anti-erbB-2 sFv (Ad21) were delivered to various breast cancer cell lines. Cell viability was determined by a proliferation assay and fluorescent microscopy allowed visualization of apoptotic cells. An erbB-2 ELISA quantified the endogenous erbB-2 levels of each cell line. The anti-erbB-2 sFv-encoding-adenovirus, Ad21, but not the beta-galactosidase encoding adenovirus, AdCMVLacZ, was cytotoxic to > 95% of the tumor cells in the MDA-MB-361 and SK-BR-3 lines, and > 60% of the tumor cells in the BT-474 line. In marked contrast, the MCF-7 and MDA-MB-231 cell lines showed no change in the rate of cell proliferation following this treatment. The cytotoxic effects generated in the first three lines were a consequence of the induction of apoptosis by the anti-erbB-2 sFv. An ELISA specific for erbB-2 showed that the breast cancer cell lines most susceptible to the anti-erbB-2 sFv, MDA-MB-361, SK-BR-3 and BT-474, overexpressed the erbB-2 protein while the cell lines demonstrating no response to the anti-erbB-2 sFv, MCF-7 and MDA-MB-231, expressed the lowest levels of erbB-2. These results demonstrate that targeted killing of erbB-2 overexpressing cells via intracellular knockout can be accomplished in the context of breast carcinoma. Furthermore, erbB-2 levels in breast tumor cells may be predictive of their sensitivity to sFv-mediated killing. The ability to accomplish selective cytotoxicity of breast cancer cell lines overexpressing the erbB-2 tumor marker should allow for derivation of clinical gene therapy strategies for breast cancer utilizing this approach.

Adenoviridae↗
PubMed1997

Oral administration of antibodies as prophylaxis and therapy in Campylobacter jejuni-infected chickens.

Passive immunity against gastrointestinal infections has recently been successfully applied as prophylaxis and therapy in patients in a variety of virally and bacterially induced infections. Campylobacter jejuni is frequently associated with acute diarrhoea in humans, and several species of animals have been shown to transmit the disease, although birds have been implicated as the main source of infection. We used bovine and chicken immunoglobulin preparations from the milk and eggs, respectively, of immunized animals for prophylactic and therapeutic treatment of chickens infected with C. jejuni. A marked prophylactic effect (a >99% decrease in the number of bacteria) was noted using either antibody preparation, whereas the therapeutic efficacy, i.e. when antibodies were given after the infection was established, was distinctly lower (80-95%) as judged by faecal bacterial counts. These observations may serve as a starting point for experiments aimed at elimination of the infection in an industrial or farm setting. It may also encourage future attempts to treat, prophylactically or therapeutically, patients with Campylobacter-induced diarrhoea.

Administration, Oral↗
PubMed1997

Role of extracellular signal-regulated protein kinases 1 and 2 in oligodendroglial process extension.

The relationship between extracellular signal-regulated protein kinase (ERK) activation and process extension in cultured bovine oligodendrocytes (OLGs) was investigated. Process extension was induced through the exposure of cultured OLGs to phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C (PKC), for various intervals. During the isolation of these OLGs from bovine brain, the original processes were lost. Therefore, any reinitiation of process extension via PMA stimulation was easily discemible through morphological monitoring. It was found that exposure of OLGs to PMA for 10 min was enough to induce OLG process extension 24-72 h later. Furthermore, this extension was still evident at least 1 week after the initial PMA stimulation, indicating that OLGs do not need continuous PKC activation to sustain process extension. Control and PMA-stimulated OLGs were also subjected to immunocytochemistry using an anti-ERK antibody selective for the mitogen-activated protein kinases p42 Erk2 (ERK2) and p44 Erk1 (ERK1) isoforms. ERK immunoreactivity in the nucleus was evident after PMA stimulation of OLGs but not in control OLGs. In parallel experiments, the control and PMA-stimulated OLGs were purified by Mono Q fractionation and subjected to ERK phosphotransferase assays using [gamma-32P]ATP and either myelin basic protein (MBP) or a synthetic peptide substrate based on the Thr97 phosphorylation site in MBP. These assays indicated that in PMA-treated OLGs, ERK activation was at least 12-fold higher than in control OLGs. Anti-ERK and anti-phosphotyrosine western blots of the assay fractions verified an enhanced phosphorylation of ERK1 and ERK2 in PMA-treated fractions relative to control fractions. When OLGs were pretreated for 15 min with the ERK kinase (MEK) inhibitor PD 098059 before PMA stimulation, they exhibited a 67% decrease in ERK activation as compared with cells treated with PMA alone. Furthermore, these MEK inhibitor-pretreated cells were still viable but showed no process extensions up to 1 week later. Therefore, we propose that a threshold level of ERK activity is required for the initiation of OLG process extension.

Animals↗
PubMed1997

Cavernous malformation presenting as an extra-axial cerebellopontine angle mass: case report.

OBJECTIVE AND IMPORTANCE: We describe a rare case of an extra-axial cavernoma of the cerebellopontine angle without internal auditory canal involvement and with an unusual appearance on preoperative magnetic resonance imaging (MRI). Only three cases of cerebellopontine angle cavernomas have been previously reported, and none of these reports included preoperative MRI. CLINICAL PRESENTATION: A young man presented with subacute left facial hypesthesia and chronic asymmetrical sensorineural hearing loss. MRI revealed a mass, which was isointense on T1- and T2-weighted images, with evidence of hemorrhage (methemoglobin and hemosiderin). The lesion did not enhance after the injection of gadolinium. INTERVENTION: The lesion was removed without difficulty by a suboccipital approach, with intraoperative electrophysiological monitoring of facial and cochlear nerves. Facial paresis cleared postoperatively. CONCLUSION: The present case suggests that the appearance of cerebelopontine angle cavernomas as revealed by MRI may be similar to that of intraparenchymal cavernomas. This is in contrast to previously reported cases of extra-axial cavernomas at other sites. Evidence of hemorrhage in an extra-axial lesion revealed by MRI suggests a possible diagnosis of cavernoma.

Adult↗
PubMed1997

Involvement of protein kinase and extraplastidic serine/threonine protein phosphatases in signaling pathways regulating plastid transcription and the psbD blue light-responsive promoter in barley.

We investigated the signaling pathways that control changes in plastid transcription in response to development and light. Plastid gene expression was analyzed in dark-grown barley (Hordeum vulgare L.) seedlings treated in vivo with an inhibitor of protein phosphatases 1 and 2A, okadaic acid (OA), or an inhibitor of protein kinases (K252a), followed by exposure of the seedlings to either red, blue, or white light. OA prevented blue light from activating the plastid pshD blue-light-responsive promoter (BLRP) and prevented red and blue light from activating the expression of the plastid-encoded rbcl and psbA and the nuclear-encoded RbcS and Lhcb genes. OA reduced total plastid transcription activity in dark- and light-grown seedlings by 77 to 80%, indicating that OA prevented light-responsive transcription by reducing total plastid transcription. In contrast, K252a activated the accumulation of mRNAs arising from the BLRP. Blue light in combination with K252a increased psbD mRNA levels in an additive manner. The results indicate that protein phosphatases 1 and/or 2A, which reside external to the organelle, are required for proper function of plastid transcription and chloroplast development, whereas a protein kinase represses the BLRP in plants grown in the dark.

Carbazoles↗
PubMed1997

Host cell-dependent alterations in envelope components of human immunodeficiency virus type 1 virions.

In addition to gp41 and gp120, an array of cell adhesion molecules is present on the envelope of human immunodeficiency virus type 1 (HIV-1). To examine the role of the host cell in the acquisition of these molecules by virions, both laboratory-adapted and primary isolates were sequentially passaged into different host cells. Viruses obtained from the various host cells were examined for the presence of 10 different cell-derived molecules by a virus binding enzyme-linked immunosorbent assay. Virus progeny raised in peripheral blood mononuclear cells expressed most of the adhesion molecules tested, with the level of LFA-1 being the highest. When viruses were passaged into CEM-SS or SupT1 cells, the expression of most of the adhesion molecules on the virus envelope was lost. In contrast, when viruses were passaged into MT2 cells, the virus progeny bore high levels of LFA-3, ICAM-1, and major histocompatibility complex classes I and II. These studies demonstrate for the first time the host cell dependence of the adhesion molecule profile present on the envelope of primary isolates of HIV-1. The presence of several adhesion molecules that have not previously been identified as components of the envelope of either laboratory or primary isolates is also described. In addition, we show that the adhesion molecule profile of the virions is acquired, or lost, within one passage and is maintained with subsequent passages in the same cell type.

Cell Adhesion Molecules↗
PubMed1997

Passive immunization against dental plaque formation in humans: effect of a mouth rinse containing egg yolk antibodies (IgY) specific to Streptococcus mutans.

Passive immunization involving the delivery of antibodies specific to pathogens of infectious diseases to the host has been an attractive approach to establish protective immunity against a variety of microbial pathogens, including Streptococcus mutans, which is the principal etiologic agent of dental caries in humans. The overall purpose of the present study was to determine the effectiveness of a mouth rinse containing antibodies to S. mutans in preventing the establishment of this bacterium in dental plaque of humans. The antibodies were derived from egg yolks obtained from hens immunized with whole cells of S. mutans grown in sucrose-containing medium. The immunoglobulin derived from the yolks (IgY) of immunized hens was characterized in vitro and in vivo in human volunteers. Cross-reactivity tests showed that immune IgY reacted with every serotype, except serotype b, which had lost its GTase activity, when the bacteria were cultured in sucrose-containing medium. Immune IgY inhibited S. mutans adherence to saliva-coated hydroxyapatite discs by 59.2%, while control IgY caused an inhibition of only 8.2%. In the short-term (4-hour) test using a mouth rinse containing 10% sucrose, immune IgY decreased the ratio of the percentage of S. mutans per total streptococci in saliva. In the long-term (7-day) test using a mouth rinse without sucrose, the ratio in saliva was not significantly reduced in the volunteers using the immune IgY due to the large standard deviation. However, comparing the ratios of the percentage of S. mutans per total streptococci in plaque of individual subjects, there was a tendency for a reduction of the ratios in the volunteers receiving the mouth rinse containing immune IgY. These results support the effectiveness of IgY with specificity to S. mutans grown in the presence of sucrose as an efficient method to control the colonization of mutans streptococci in the oral cavity of humans.

Antibodies, Bacterial↗
PubMed1997

Search patterns using the line bisection test for neglect.

BACKGROUND/OBJECTIVE: Neglect has been attributed to sensory-attentional, motor-intentional, and representational disorders. Although patients with neglect may have defective visual exploration, the nature of this exploration deficit has not been entirely elucidated. The purpose of this study is to learn how, compared with control subjects, a patient with neglect performs visual exploration. METHODS: The line bisection test is commonly used to detect and evaluate the performance of patients with unilateral or hemispatial spatial neglect. We tested an experimental subject with left premotor-intentional neglect using an infrared eye monitoring instrument. Thirteen right-handed healthy volunteers served as control subjects. From different starting ocular positions, we assessed the direction of eye movements when the subjects initially oriented to the line, scanned the line, and then attempted to look at the center of the line. RESULTS: Independent of starting ocular position, normal subjects most often initially orient to the left end of the line, scan rightward, then look leftward to the center. However, the eye movements in our experimental subject with neglect were directed to the right end of the line without any scanning or leftward eye movement back to the center of the line. CONCLUSION: Our subject with neglect had defective line exploration that may be attributed to a directional ocular motor intentional deficit.

Adult↗
PubMed1997

Protective effect of green tea extract and tea polyphenols against the cytotoxicity of 1,4-naphthoquinone in isolated rat hepatocytes.

The cytoprotective effect of green tea extract and its phenolic compounds against 1,4-naphthoquinone-induced hepatotoxicity was evaluated in primary cultured rat hepatocytes. After exposure to 1,4-naphthoquinone, lactate dehydrogenase (LDH) leakage and cell viability were both improved by the presence of the tea extract and tea polyphenols. This cytoprotective effect was related to the structure of tea polyphenols, the galloyl group of (-)-epigallocatechin-3-gallate and (-)-epicatechin-3-gallate being particularly effective. The production of liquid peroxidation by 1,4-naphthoquinone was not inhibited by the tea extract nor by tea polyphenol addition. After 2 h of incubation, the protein thiol concentration was reduced by 1,4-naphthoquinone, but this reduction was prevented by the tea extract and tea polyphenols. The reduction in protein thiol content of the cells closely paralleled the LDH leakage and loss of cell viability. These results suggest that the mechanism of protection by tea polyphenols against 1,4-naphthoquinone-induced toxicity to rat hepatocytes was due to the maintenance of protein thiol levels.

Animals↗
PubMed1997

Blood flow limitations of solute transport across the visceral peritoneum.

In a previous study, no limitations to urea transfer across the parietal peritoneum were demonstrated with decreases in local blood flow of 70%. It was hypothesized that the visceral peritoneum would have similar characteristics. To address this problem at the tissue level, diffusion chambers were affixed to the serosal side of the stomach, cecum, or liver of anesthetized rats (n = 6 each tissue), and solutions containing 14C urea were placed in the chamber. During each experiment, the local chamber blood flow was measured with laser Doppler flowmetry, and, simultaneously, the disappearance of the tracer versus time was determined under three conditions: control, after 60 to 70% blood flow reduction, and postmortem (flow = 0). The results showed no difference in the urea mass transfer coefficient (MTC; mean +/- SEM; cm/min x 10[3]) between control and blood flow reduction for the stomach (4.0 +/- 0.4 versus 3.6 +/- 0.3) or for the cecum (4.6 +/- 0.3 versus 4.0 +/- 0.3). However, the MTC was significantly decreased by local blood flow reduction in the liver (5.4 +/- 0.2 versus 2.6 +/- 0.2). Postmortem data demonstrated significant reductions in the MTC with blood flow equal to zero. It is concluded that a 60 to 70% blood flow reduction from control values does not limit solute transperitoneal transfer in the hollow viscera but causes significant changes in the mass transfer across the liver surface. Because the liver makes up only a small portion of the effective exchange area, overall transperitoneal solute transfer should not be greatly affected by significant decreases in blood flow.

Animals↗
PubMed1997

A method to test blood flow limitation of peritoneal-blood solute transport.

Current transperitoneal transport models assume that effective blood flow to the microcirculation does not limit solute exchange with dialysate in the cavity. Despite evidence that gas transfer across the peritoneum (assumed to equal the effective blood flow) occurs at rates that exceed maximum urea transfer rates by a factor of two to three, the assumption has been strongly challenged. To address this problem at the tissue level, a technique to determine the effect of local blood flow on small-solute transport was developed in this study. Diffusion chambers were affixed to the serosal side of the anterior abdominal wall of rats, and solutions containing radiolabeled urea or mannitol were placed in the chambers. During each experiment, the local blood flow beneath the chamber was monitored with laser Doppler flowmetry and the disappearance of the tracer versus time was simultaneously measured under three conditions of blood flow: control, 30% of control, and zero blood flow. The results demonstrated no significant differences for either solute between control and the condition in which blood flow was reduced by 70%. However, there was a significant reduction in the rate of mass transfer with no blood flow. It was concluded that blood flow at > or = 30% of control values does not limit solute transfer across the abdominal wall peritoneum during dialysis.

Abdominal Muscles↗
PubMed1997

Aspergillus nidulans infection in a patient with chronic granulomatous disease.

Aspergillus nidulans is one of the several species of Aspergillus with low pathogenicity. The significant infections of A. nidulans in human have rarely been reported, almost exclusively in patients with chronic granulomatous disease (CGD). CGD is a primary immunodeficiency disease which results from the absence of the NADPH oxidase in the phagocytic cells, leading to recurrent pyogenic infection and granuloma and abscess formation. Here we report a fatal case A. nidulans infection in a six-year-old boy with chronic granulomatous disease. A. nidulans was isolated from the culture of a paraspinal abscess and Aspergillus was detected in the surgical tissue by in situ hybridization. The patient succumbed despite prolonged treatment with high-dose amphotericin B, itraconazole and interferon-alpha. To our knowledge, this is the first report of A. nidulans infection in Korea.

Aspergillosis↗
PubMed1997

Changes of the plasma endothelin in adaptation to increased salt intake in rats.

OBJECTIVES: Roles for vascular endothelial hormones in body fluid balance have been variously suggested. The present study was aimed at investigating whether the plasma endothelin is altered in responses to acute and chronic perturbations in body fluid balance. METHODS: Effects of intravenous infusion of MG-nitro-L-arginine methyl ester (L-NAME), a competitive inhibitor of endothelium-derived nitric oxide (NO) synthesis, on urinary excretion, blood pressure and plasma levels of endothelin were examined in rats kept on either normal or high-salt diet for two weeks. The plasma endothelin levels in response to an acute extracellular volume expansion (VE) were also determined in normal and 2-kidney, 1 clip (2K1C) hypertensive rats. RESULTS: L-NAME (20 and 200 micrograms.kg(-1) per min) elicited diuretic and natriuretic effects in association with increased blood pressure both in normal and high-salt rats. In high-salt rats, however, the urinary response to L-NAME was attenuated and the pressor response was augmented compared with the control. High-salt intake per se caused a small, but significant, increase of the plasma endothelin. L-NAME (200 micrograms(-1) per min) markedly increased the plasma endothelin was also marginally increased following VE, the magnitude of which did not differ between the normal and 2K1C rats. CONCLUSION: These results suggest that the endothelin system takes part in adaptation to increased salt-intake. Another evidence indicating a negative modulation of NO on the release of endothelin is also provided.

Adaptation, Physiological↗