Biomedical subjects

J H Lim

Publications and source records attributed to J H Lim.

At least 19 recordsLinked to original sources

PubMed1999

Characterization of two new channel protein genes in Arabidopsis.

Aquaporins, small channel proteins, found in a variety of organisms are members of the major intrinsic protein (MIP) superfamily and have been shown to facilitate water transport when expressed in Xenopus oocytes. We isolated two Arabidopsis cDNAs, SIMIP and SITIP, that encode protein homologues of the MIP superfamily. SIMIP exhibits a high degree of sequence homology to PIP3 and MIP1, and thus may belong to the plasmamembrane intrinsic protein (PIP) subfamily, whereas salt-stress inducible tonoplast intrinsic protein (SITIP) is highly homologous to VM23 and gamma-TIP, and therefore may belong to the TIP subfamily. Expression studies revealed that the two genes showed a different expression pattern. The SIMIP gene was expressed in a tissue-specific manner, for example, its highest transcript level is found in flowers, relatively low levels in siliques, and very low level in leaves and roots. In contrast, SITIP was expressed in nearly equal amounts in all the tissues we examined. Also, the expression of SIMIP and SITIP showed a temporal regulation pattern. For example, the highest expression level was at 1 week after germination. In addition, the transcript levels of SIMIP and SMTIP were increased upon NaCl and ABA treatments. The biological function of the 2 genes were investigated using two NaCl stress-sensitive yeast mutant strains. The mutant yeast cells expressing these 2 genes were more resistant to high NaCl conditions. The results suggest that the proteins encoded by these genes may be involved in the osmoregulation in plants under high osmotic stress such as under a high salt condition.

Abscisic Acid↗

PubMed1999

Fas ligand and Fas are expressed constitutively in human astrocytes and the expression increases with IL-1, IL-6, TNF-alpha, or IFN-gamma.

Fas ligand (FasL) and Fas are mediators of apoptosis, which are implicated in the peripheral deletion of autoimmune cells, activation-induced T cell death, and cytotoxicity mediated by CD8+ T cells. Fas is also believed to be involved in several central nervous system diseases, but until now, the effector cells expressing FasL in the brain have not been identified. We investigated the expression levels of Fas and FasL with the stimulation of cytokines and the possible effector cells targeting Fas-bearing cells. Our data demonstrated that: 1) FasL is expressed constitutively on astrocytes taken from a fetus or an adult and that its expression increases when these cells are treated with IL-1, IL-6, or TNF-alpha in which the pretreatment of IFN-gamma triggers astrocytes to express more FasL; 2) astrocytes induce apoptosis in MOLT-4 cells through FasL; 3) Fas is also expressed constitutively and is up-regulated by IL-1, IL-6, or TNF-alpha in which the pretreatment of IFN-gamma triggers astrocytes to express more Fas; 4) apoptosis occurs when fetal astrocytes are treated with agonistic anti-Fas IgM Ab after culture with IFN-gamma and TNF-alpha; and 5) TNF-related apoptosis inducing ligand is up-regulated in fetal astrocytes with stimuli of IL-1 or TNF-alpha. These findings suggest a possible role of astrocytes in the induction of apoptosis in central nervous system diseases.

Adult↗

PubMed1999

Enhanced hatching rate of bovine IVM/IVF/IVC blastocysts using a 1.48-micron diode laser beam.

PURPOSE: Our purpose was to test whether zona pellucida (ZP) drilling using a 1.48-micron diode laser beam on bovine IVM/IVF/IVC blastocysts is effective for embryo hatching. METHODS: Blastocysts produced in vitro at day 7 after IVF were divided into control and laser-drilled groups, respectively. RESULTS: When the rates of in vitro development of bovine embryos were examined, the average cleavage rate (> or = two-cell) was 82.3% and the blastocyst rate at day 7 after IVF was 32.5%. Using these blastocysts, when the laser drilling effect was investigated at 48 hr after treatment, the total hatching rate in the laser-drilled group (98.0%) was significantly higher than that in the control group (60.0%) (P < 0.001). Especially, the hatched rate of the laser-drilled group (68.0%) was significantly enhanced compared with that of the control group (30.0%) (P < 0.001). CONCLUSIONS: These results demonstrated that laser ZP drilling on bovine IVM/IVF/IVC blastocysts can significantly increase the hatching rate.

Animals↗

PubMed1999

An Arabidopsis GSK3/shaggy-like gene that complements yeast salt stress-sensitive mutants is induced by NaCl and abscisic acid.

GSK3/shaggy-like genes encode kinases that are involved in a variety of biological processes. By functional complementation of the yeast calcineurin mutant strain DHT22-1a with a NaCl stress-sensitive phenotype, we isolated the Arabidopsis cDNA AtGSK1, which encodes a GSK3/shaggy-like protein kinase. AtGSK1 rescued the yeast calcineurin mutant cells from the effects of high NaCl. Also, the AtGSK1 gene turned on the transcription of the NaCl stress-inducible PMR2A gene in the calcineurin mutant cells under NaCl stress. To further define the role of AtGSK1 in the yeast cells we introduced a deletion mutation at the MCK1 gene, a yeast homolog of GSK3, and examined the phenotype of the mutant. The mck1 mutant exhibited a NaCl stress-sensitive phenotype that was rescued by AtGSK1. Also, constitutive expression of MCK1 complemented the NaCl-sensitive phenotype of the calcineurin mutants. Therefore, these results suggest that Mck1p is involved in the NaCl stress signaling in yeast and that AtGSK1 may functionally replace Mck1p in the NaCl stress response in the calcineurin mutant. To investigate the biological function of AtGSK1 in Arabidopsis we examined the expression of AtGSK1. Northern-blot analysis revealed that the expression is differentially regulated in various tissues with a high level expression in flower tissues. In addition, the AtGSK1 expression was induced by NaCl and exogenously applied ABA but not by KCl. Taken together, these results suggest that AtGSK1 is involved in the osmotic stress response in Arabidopsis.

Abscisic Acid↗

PubMed1999

Regenerative nodules in liver cirrhosis: findings at CT during arterial portography and CT hepatic arteriography with histopathologic correlation.

PURPOSE: To determine the appearance of regenerative nodules in patients with liver cirrhosis at computed tomography (CT) during arterial portography (CTAP) and CT hepatic arteriography (CTHA). MATERIALS AND METHODS: CTAP and CTHA of the liver were performed in 28 consecutive patients with hepatocellular carcinoma (HCC) who were scheduled to undergo partial resection of the liver. Helical CTAP was performed after contrast material injection into the superior mesenteric artery followed by helical CTHA after contrast material injection into the hepatic artery. CT scans were analyzed for the presence of identifiable nodules and their size; results were correlated with gross and microscopic findings. RESULTS: Resected livers showed cirrhosis in 20 patients, chronic hepatitis in four, and normal liver in four. Among the 20 patients with cirrhosis, regenerative nodules were demonstrated as enhancing 3-10 mm nodules surrounded by lower attenuation fibrous septa 0.8-1.5 mm thick at CTAP in seven patients and nonenhancing nodules of the same size surrounded by enhancing fibrous septa at CTHA in 15 patients. The degree of fibrosis determined the conspicuity of nodules. CONCLUSION: Regenerative nodules in cirrhotic liver are visualized as enhancing nodules surrounded by lower attenuation thin septa at CTAP and nonenhancing nodules surrounded by enhancing fibrous septa at CTHA. CTHA is more sensitive than CTAP in depicting regenerative nodules (P < .005).

Carcinoma, Hepatocellular↗

PubMed1999

Assessment of pancreatic invasion in patients with advanced gastric carcinoma: usefulness of the sliding sign on sonograms.

OBJECTIVE: The purpose of our study was to determine the value of the sliding sign on sonograms in evaluating direct pancreatic invasion of advanced gastric carcinoma. SUBJECTS AND METHODS: Sonography was performed prospectively on 70 patients with pathologically proven advanced gastric carcinoma. Sonography was directed at the detection of motion between the gastric mass and the pancreas. When the gastric mass showed complete sliding motion against the pancreas or partial sliding motion with a preserved echogenic fat plane between the two organs on respiration or on extrinsic compression with a transducer (positive sliding sign), patients were considered to have no pancreatic invasion. When the gastric mass had no sliding motion against the pancreas or partial sliding motion with a disrupted echogenic fat plane between the two organs (negative sliding sign), patients were considered to have pancreatic invasion. After sonography, all patients underwent surgery and the results of sonography were compared with the findings at surgery and pathology. RESULTS: Of the 70 patients, 17 had pancreatic invasion and 53 had no evidence of pancreatic invasion at surgery and pathology. The sliding sign on sonography yielded an 80% sensitivity, 96% specificity, and 90% accuracy for the diagnosis of pancreatic invasion. CONCLUSION: Application of the sliding sign on sonography was simple and highly accurate in the diagnosis of pancreatic invasion by advanced gastric carcinoma. The sliding sign may prove useful in the preoperative detection of pancreatic invasion by gastric carcinoma when CT has been inconclusive.

Carcinoma↗

PubMed1998

Induction of late activation events by Igbeta signaling subunit of B-cell receptor in Jurkat T-cell without tyrosine phosphorylation.

T-lymphocyte activation consists of multiple intracellular signaling events, eventually leading to cellular proliferation by the control of cytokine gene expression and the acquisition of diverse effector function. To investigate the functional specificity of ITAM (Immunoreceptor Tyrosine-based Activation Motif), chimeric molecules CD8-zeta, CD8-Igalpha, CD8-Igbeta, which contain the extracellular and transmembrane domains of the human CD8alpha molecule and the cytoplasmic tail of T-cell receptor (TcR) chain, Igalpha or Igbeta subunit of B-cell receptor, respectively, were stably expressed in a Jurkat cell line. Upon stimulation with anti-CD8 mAb OKT8, CD8-zeta and CD8-Igalpha chimeric proteins induced tyrosine phosphorylation of various cytoplasmic substrates as seen in TcR stimulation. They were also capable of stimulating IL-2 gene expression in a NF-AT dependent manner and inducing CD69 expression on the surface. However, stimulation of CD8-Igbeta can induce activation of CD69 surface expression and IL-2 gene expression equivalent to the level by CD8-Igalpha and CD8-zeta without induction of the tyrosine phosphorylation of intracellular signaling molecules. These results suggested that some of signaling chains containing ITAM may utilize a signal pathway without substrate tyrosine phosphorylation during T-cell activation leading to the IL-2 secretion.

Antigens, CD↗

PubMed1998

A new splicing variant of a type III POU gene from zebrafish encodes a POU protein with a distinct C-terminal.

A zebrafish POU protein cDNA clone was isolated and sequenced. It appears to be a novel splicing variant of the previously reported zebrafish POU gene zp-12. There are four splicing variants and at least three of them lead to different C-terminal amino acid sequences. The four splicing variants are differentially regulated during development, indicating that they may be functionally diversified.

Alternative Splicing↗

PubMed1998

Molecular cloning of a novel Ca2+-binding protein that is induced by NaCl stress.

Plant responses to high salt stress have been studied for several decades. However, the molecular mechanisms underlying these responses still elude us. In order to understand better the molecular mechanism related to NaCl stress in plants, we initiated the cloning of a large number of NaCl-induced genes in Arabidopsis. Here, we report the cloning of a cDNA encoding a novel Ca2+-binding protein, named AtCP1, which shares sequence similarities with calmodulins. AtCP1 exhibits, in particular, a high degree of amino acid sequence homology to the Ca2+-binding loops of the EF hands of calmodulin. However, unlike calmodulin, AtCP1 appears to have only three Ca2+-binding loops. We examined Ca2+ binding of the protein by a Ca2+-dependent electrophoretic mobility shift assay. A recombinant AtCP1 protein that was expressed in Escherichia coli did show a Ca2+-dependent electrophoretic mobility shift. To gain insight into the expression of the AtCP1 gene, northern blot analysis was carried out. The AtCP1 gene had a tissue-specific expression pattern: high levels of expression in flower and root tissues and nearly undetectable levels in leaves and siliques. Also, the expression of the AtCP1 gene was induced by NaCl treatment but not by ABA treatment. Finally, subcellular localization experiments using an AtCP1:smGFP fusion gene in soybean suspension culture cells and tobacco leaf protoplasts indicate that AtCP1 is most likely a cytosolic protein.

Amino Acid Sequence↗

PubMed1998

Molecular cloning of an Arabidopsis cDNA encoding a dynamin-like protein that is localized to plastids.

Dynamin-related proteins are high molecular weight GTPase proteins found in a variety of eukaryotic cells from yeast to human. They are involved in diverse biological processes that include endocytosis in animal cells and vacuolar protein sorting in yeast. We isolated a new gene, ADL2, that encodes a dynamin-like protein in Arabidopsis. The ADL2 cDNA is 2.68 kb in size and has an open reading frame for 809 amino acid residues with a calculated molecular mass of 90 kDa. Sequence analysis of ADL2 revealed a high degree of amino acid sequence similarity to other members of the dynamin superfamily. Among those members ADL2 was most closely related to Dnm1p of yeast and thus appears to be a member of the Vps1p subfamily. Expression studies showed that the ADL2 gene is widely expressed in various tissues with highest expression in flower tissues. In vivo targeting experiments showed that ADL2:smGFP fusion protein is localized to chloroplasts in soybean photoautroph cells. In addition experiments with deletion constructs revealed that the N-terminal 35 amino acid residues were sufficient to direct the smGFP into chloroplasts in tobacco protoplasts when expressed as a fusion protein.

Amino Acid Sequence↗

PubMed1998

Anatomical communications of the perirenal space.

There are controversies over the anatomical communications between the perirenal space and the adjacent extraperitoneal spaces. Clinical studies, mainly based on CT, show fluid collections extending into the adjacent space; into the bare area of the liver on the right, into the superior extraperitoneal space on the left, towards the midline from each perirenal space, and into the lower retroperitoneal space of the abdomen and pelvis. There are certain constant anatomical barriers limiting free extension of fluid or pathology. The pattern of fluid collection in the perirenal space and extension into the adjacent extraperitoneal space is relatively consistent although it varies with the amount and nature of the pathological fluid collection. This pictorial review illustrates anatomical barriers and CT findings of perirenal fluid collections and their extension into adjacent extraperitoneal spaces.

Adult↗

PubMed1998

Computed radiography of the chest in patients with paraesophageal varices: diagnostic accuracy and characteristic findings.

OBJECTIVE: The purpose of our study was to determine the diagnostic accuracy of computed radiography of the chest in the detection of paraesophageal varices and to describe the characteristic radiographic findings. SUBJECTS AND METHODS: From June 1995 through May 1997, in 100 consecutive patients, portal hypertension was diagnosed through both clinical and radiologic evidence. Computed radiographs of the chest and hepatic helical CT scans of these 100 patients with portal hypertension and 20 control subjects were analyzed by two chest radiologists and one abdominal radiologist, who were not aware of the results of the other study. RESULTS: On CT, paraesophageal varices were seen in 38 (38%) of 100 patients with portal hypertension. Overall, the sensitivity, specificity, and accuracy of chest computed radiography in the detection of paraesophageal varices were 53% (20/38), 90% (74/82), and 78% (94/120), respectively. In the patients with paraesophageal varices, splenomegaly (29/38, 76%), lateral displacement or obliteration of the inferior portion of the azygoesophageal interface (18/38, 47%), obliteration or nodularity of the inferior portion of the descending thoracic aorta interface (9/38, 24%), lateral displacement of the right inferior paraspinal interface (6/38, 16%), lateral displacement of the left inferior paraspinal interface (4/38, 11%), and varices in the left inferior pulmonary ligament (1/38, 3%) were seen on chest computed radiographs. Paraesophageal varices smaller than the diameter of the descending thoracic aorta (usually <2.5 cm) were not detected. CONCLUSION: Although chest computed radiography is only moderately sensitive for paraesophageal varices, the findings are characteristic when well developed, with a limited differential diagnosis. Splenomegaly, whether detected clinically or radiographically, eliminates most other diagnostic possibilities.

Adult↗

PubMed1998

The electroretinogram in chronic renal failure.

To evaluate functional changes of the retina in patients with chronic renal failure (CRF), we analyzed maximal combined response according to the recommendations of the International Society of Clinical Electrophysiology of Vision. Oscillatory potentials were extracted from maximal combined response by high pass filtering. Because most CRF patients suffer from hypertension, hypertensive patients were selected for the control group. Values recorded in CRF patients were compared with those recorded in hypertensive patients and in the normal control group. CRF patients underwent laboratory tests which included complete blood cell count and the determination of blood urea nitrogen, creatinine, natrium, and potassium levels. The parameters of electroretinograms obtained from CRF patients were compared with those obtained from the normal control group, in the former group all amplitudes were significantly lower and all implicit times except those of b-wave were significantly delayed (P < 0.05). In CRF patients, decreased b-amplitude of maximal combined response and delayed implicit time of oscillatory potentials 1, and 2 were significantly different from those in hypertensive patients (P < 0.05). CRF patients had anemia, and their blood urea nitrogen and creatinine levels appeared abnormal. There was, however, no clinical correlation between biochemical data and electroretinograms. Consequently, retinal function in CRF patients was severely damaged compared with control groups (i.e., normal and hypertensive patients). We suggest that these findings are result of anemia and uremia in addition to hypertensive retinal damage.

Adult↗

PubMed1997

Experience-dependent modifications in MAP2 phosphorylation in rat olfactory bulb.

Microtubule-associated protein 2 (MAP2) is a neuron-specific cytoskeletal protein, enriched in dendrites and cell bodies, that helps determine dendritic shape. MAP2 regulates microtubule stability in a phosphorylation-dependent manner. The present study used immunocytochemistry with phosphoepitope-specific and phosphorylation state-independent antibodies to examine experience-dependent changes in MAP2 expression during postnatal development of the olfactory bulb. Our results demonstrate that immunoreactivity reflecting total MAP2 expression reaches a maximal level by postnatal day 20 (P20). The degree of staining for phosphoindependent forms of MAP2 is relatively unaffected by blocking odorant passage to one half the nasal epithelium via unilateral naris closure, a manipulation that attenuates physiological activity in the bulb. However, olfactory restriction from P1 dramatically reduces immunoreactivity for antibody AP18, which recognizes MAP2 only when phosphorylated on Ser136. Quantification of staining in the granule cell layer indicates that the greatest difference (64%) between control and experimental bulbs occurs after occlusion from P1 to P30 compared with animals deprived from P1 to P10 or P1 to P20. The shift in MAP2 phosphorylation occurs even when deprivation is delayed until P30, after the sensitive period for experience-dependent changes in bulb volume. Thus, the degree of the phosphorylation shift depends on the duration but not the time of onset of naris closure. Because staining for phosphorylation-independent forms of MAP2 is unchanged by naris closure, the total amount of the protein per unit area is probably not significantly altered. However, the large reductions of AP18-immunoreactivity in the bulb after olfactory restriction suggest that there is an activity-dependent stimulation of MAP2 phosphorylation.

Animals↗

PubMed1997

Activity-dependent regulation of calcium-binding proteins in the developing rat olfactory bulb.

Intracellular calcium, important in a variety of second messenger cascades, is regulated in part by calcium-binding proteins such as calretinin, parvalbumin, and calbindin. These proteins are highly concentrated in the rat main olfactory bulb and are localized in distinct neuronal populations. In the present study, postnatal expression was characterized immunohistochemically in normal rats and in rats with functional olfactory deprivation caused by unilateral naris closure, a manipulation that attenuates electrical activity in the bulb. Bulbs were examined from rats that had undergone naris closure or sham surgery on either postnatal day 1 (P1) or P30 and were allowed varying subsequent survival times. Each of the calcium-binding proteins showed both distinct patterns of early expression and differential susceptibility to olfactory restriction. For example, at P10, the densest immunoreactivity was observed for calretinin, a protein whose expression was the least affected by naris closure. After occlusion from P1-P30, there was a 30% reduction in the density of calbindin-immunoreactive profiles in the glomerular layer, and parvalbumin-immunoreactive profiles were reduced by 64% in the external plexiform layer. Unlike many other changes induced by deprivation, the effects of olfactory restriction on calbindin and parvalbumin expression were not age dependent: naris closure from P30-P60 caused similar substantial decreases in calbindin and parvalbumin immunoreactivities. These data demonstrate that the expression of calbindin and parvalbumin in rat bulb is regulated, in part, by afferent activity that is associated with full sensory experiences. The reductions of these calcium-binding proteins following olfactory deprivation are likely to be commensurate with altered control of intracellular calcium.

Animals↗

PubMed1997

The crystal structure of an Fe-superoxide dismutase from the hyperthermophile Aquifex pyrophilus at 1.9 A resolution: structural basis for thermostability.

Superoxide dismutase (SOD) from Aquifex pyrophilus, a hyperthermophilic bacterium, is an extremely heat-stable enzyme that maintains about 70% of its activity after heat treatment for 60 minutes at 100 degrees C. To understand the molecular basis of thermostability of this enzyme, we have determined the crystal structure of A. pyrophilus superoxide dismutase (Ap SOD), an Fe containing homotetrameric enzyme, at 1.9 A resolution, and compared it with SOD structures from a mesophile and a thermophile, and other enzyme structures from other hyperthermophiles. The structure has been refined to a crystallographic R-factor (I > 2sigma) of 17.0% and R-free (I > 2sigma) of 19.9%. While the overall structure of the Ap SOD monomer is similar to the other SODs, significant conformational differences are observed in a highly variable loop region and the C-terminal helix. The conformational differences in these regions alter the subunit arrangement of this enzyme and generate a very compact tetramer. Structural comparisons of three SODs have revealed that Ap SOD has some stabilizing features at both the tertiary and the quaternary structural level: The Ap SOD monomer contains a large number of ion-pairs and the Ap SOD tetramer has a dramatically increased buried surface area per monomer. Comparisons of the Ap SOD structure with that of other known enzymes from hyperthermophiles reveal that the increased number of intrasubunit ion-pairs is a common feature.

Amino Acid Sequence↗

PubMed1997

Cloning and expression of superoxide dismutase from Aquifex pyrophilus, a hyperthermophilic bacterium.

A superoxide dismutase (SOD) gene of Aquifex pyrophilus, a marine hyperthermophilic bacterium, was cloned, sequenced, expressed in Escherichia coli, and its gene product characterized. This is the first SOD from a hyperthermophilic bacterium that has been cloned. It is an iron-containing homo-oligomeric protein with a monomeric molecular mass of 24.2 kDa. The DNA-derived amino acid sequence is more similar to those of known Mn- and Fe-SODs from thermophilic archaea than of Cu, Zn-SODs. The metal binding residues found in all SOD sequences from different species are also conserved in A. pyrophilus SOD. The protein is biochemically active only as an oligomer and is resistant to thermal denaturation.

Amino Acid Sequence↗

PubMed1997

Protection of ischemic hippocampal neurons by ginsenoside Rb1, a main ingredient of ginseng root.

Our previous study showed that the oral administration of red ginseng powder before but not after transient forebrain ischemia prevented delayed neuronal death in gerbils, and that a neuroprotective molecule within red ginseng powder was ginsenoside Rb1. However, it remains to be clarified whether or not ginsenoside Rb1 acts directly on the ischemic brain, and the mechanism by which ginsenoside Rb1 protects the ischemic CA1 neurons is not determined. Without elucidation of the pharmacological property of ginsenoside Rb1, the drug would not be accepted as a neuroprotective agent. The present study demonstrated that the intracerebroventricular infusion of ginsenoside Rb1 after 3.5 min or 3 min forebrain ischemia, precluded significantly the ischemia-induced shortening of response latency in a step-down passive avoidance task and rescued a significant number of hippocampal CA1 neurons from lethal ischemic damage. The intracerebroventricular infusion of ginsenoside Rb1 did not affect hippocampal blood flow or hippocampal temperature except that it caused a slight increase in hippocampal blood flow at 5 min after transient forebrain ischemia. Furthermore, ginsenoside Rb1 at concentrations of 0.1-100 fg/ml (0.09-90 fM) rescued hippocampal neurons from lethal damage caused by the hydroxyl radical-promoting agent FeSO4 in vitro, and the Fenton reaction system containing p-nitrosodimethylaniline confirmed the hydroxyl radical-scavenging activity of ginsenoside Rb1. These findings suggest that the central infusion of ginsenoside Rb1 after forebrain ischemia protects hippocampal CA1 neurons against lethal ischemic damage possibly by scavenging free radicals which are overproduced in situ after brain ischemia and reperfusion. The present study may validate the empirical usage of ginseng root over thousands of years for the prevention of cerebrovascular diseases.

Animals↗