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Biomedical subjects

I H Lee

Publications and source records attributed to I H Lee.

At least 37 records · Page 2Linked to original sources
PubMed2001

Isolation and characterization of a Bacillus thuringiensis ssp. kurstaki strain toxic to Spodoptera exigua and Culex pipiens.

A strain of Bacillus thuringiensis with dual toxicity was isolated from Korean soil samples and named K2. K2 was determined as ssp. kurstaki (H3a3b3c) by serological test and produced bipyramidal-shaped parasporal inclusions. The plasmid and protein profiles of B. thuringiensis K2 were different from those of the reference strain, ssp. kurstaki HD-1. To verify gene type of B. thuringiensis K2, PCR analysis with specific cry gene primers was performed. The result showed that B. thuringiensis K2 had cry1Aa, cry1Ab, cry1C, and cry1D type genes, whereas ssp. kurstaki HD-1 had cry1Aa, cry1Ab, cry1Ac, and cry2 type genes. In addition, B. thuringiensis K2 had high toxicity against Spodoptera exigua and Culex pipiens, whereas B. thuringiensis ssp. kurstaki HD-1 does not have high toxicity against these two insect species.

Animals↗
PubMed2001

Induction of remission with intravenous immunoglobulin and cyclophosphamide in steroid-resistant Evans' syndrome associated with dermatomyositis.

Evans' syndrome is characterised by the simultaneous or sequential occurrence of Coombs'-positive haemolytic anaemia (AIHA) and immune thrombocytopenia without underlying aetiology. It has been found to be associated with collagen vascular diseases, especially systemic lupus erythematosus (SLE) and scleroderma. However, Evans' syndrome with dermatomyositis is very rare. A 59-year-old woman, who had been taking high-dose prednisolone for a month and cyclosporin for 10 days for dermatomyositis, developed purpura on the left popliteal fossa. The platelet and haemoglobin levels decreased to 77,000/mm3 and 9.8 g/dl, respectively. Antiplatelet antibody was positive. Thrombocytopenia responded to intravenous immunoglobulin (IVIG) for a short time, but further decreased in a week. Her blood film showed features of haemolytic anaemia. Laboratory findings showed reticulocytosis and a positive direct Coombs' test. Bone marrow examination showed a mild hyperplasia of erythroid precursors and megakaryocytes. The patient was successfully treated with cyclophosphamide in addition to oral prednisolone. AIHA in connective tissue disease may develop gradually and show a benign clinical course in most patients. Therefore, we suggest that patients with dermatomyositis and anaemia should always be checked for haemolysis if there is no other explanation.

Anemia, Hemolytic, Autoimmune↗
PubMed2001

Optical organophosphorus biosensor consisting of acetylcholinesterase/viologen hetero Langmuir-Blodgett film.

The fiber-optic biosensor consisting of an acetylcholinesterase (AChE)-immobilized Langmuir-Blodgett (LB) film was developed to detect organophosphorus compounds in contaminated water. The sensing scheme was based on the decrease of yellow product, o-nitrophenol, from a colorless substrate, o-nitrophenyl acetate, due to the inhibition by organophosphorus compounds on AChE. Absorbance change of the product as the output of enzyme reaction was detected and the light was guided through the optical fibers. The enzyme portion of the sensor system was fabricated by the LB technique for formation of the enzyme film. AChE-immobilized LB film was formed by adsorbing the enzyme molecules onto a viologen monolayer using the electrostatic force. The proposed kinetics for irreversible inhibition of organophosphorus compounds on AChE agreed well with the experimental data. The surface topography of AChE-immobilized LB film was investigated by atomic force microscope (AFM). The immobilized AChE had the maximum activity at pH 7. The proposed biosensor could successfully detect the organophosphorus compounds up to 2 ppm and the response time to steady signal of the sensor was about 10 min.

Acetylcholinesterase↗
PubMed2001

Null mutants of the neurospora actin-related protein 1 pointed-end complex show distinct phenotypes.

Dynactin is a multisubunit complex that regulates the activities of cytoplasmic dynein, a microtubule-associated motor. Actin-related protein 1 (Arp1) is the most abundant subunit of dynactin, and it forms a short filament to which additional subunits associate. An Arp1 filament pointed-end--binding subcomplex has been identified that consists of p62, p25, p27, and Arp11 subunits. The functional roles of these subunits have not been determined. Recently, we reported the cloning of an apparent homologue of mammalian Arp11 from the filamentous fungus Neurospora crassa. Here, we report that N. crassa ro-2 and ro-12 genes encode the respective p62 and p25 subunits of the pointed-end complex. Characterization of Delta ro-2, Delta ro-7, and Delta ro-12 mutants reveals that each has a distinct phenotype. All three mutants have reduced in vivo vesicle trafficking and have defects in vacuole distribution. We showed previously that in vivo dynactin function is required for high-level dynein ATPase activity, and we find that all three mutants have low dynein ATPase activity. Surprisingly, Delta ro-12 differs from Delta ro-2 and Delta ro-7 and other previously characterized dynein/dynactin mutants in that it has normal nuclear distribution. Each of the mutants shows a distinct dynein/dynactin localization pattern. All three mutants also show stronger dynein/dynactin-membrane interaction relative to wild type, suggesting that the Arp1 pointed-end complex may regulate interaction of dynactin with membranous cargoes.

Adenosine Triphosphatases↗
PubMed2001

Moyamoya disease initially presenting visual field defect.

Progressive narrowing of distal carotid arteries and the development of compensatory fine networks are the characteristic findings of moyamoya disease. Cerebral infarction in moyamoya disease is due to a decreased blood flow and shows an uneven distribution in the distal bed of the anterior and middle cerebral arteries. The progression of disease in the posterior circulation follows that in the anterior circulation. Posterior circulation symptoms due to cerebral infarction usually occur in the advanced stage of the disease and follow the anterior circulation symptoms. We encountered an unusual case of moyamoya disease which initially presented with a transient visual field defect. One month later our patient developed blindness and her cerebral angiography showed advanced moyamoya disease.

Adult↗
PubMed2001

Depletion of plasma factor XIII prevents disseminated intravascular coagulation-induced organ damage.

The impact of clot stability affecting the vasculopathy and tissue necrosis in Shwartzman reaction was investigated using plasma Factor XIII A2-depleted rabbit (FXIII-DR). Plasma Factor XIIIA2 (FXIIIA2) was depleted by infusion of the mono-specific goat anti-rabbit FXIIIA2 IgG. Generalized Shwartzman reaction (GSR) was induced by priming and challenged by i.v. injection of LPS and local Shwartzman reaction (LSR) was primed by intradermal injection of LPS and challenged by i.v. injection of LPS. Histological examination of the GSR animals showed, extensive thrombi accumulation in renal tubules and bilateral cortical necrosis of kidney in 8 out of 10 rabbits but none in the FXIII-DR. Fibrinogen levels were elevated to 3 approximately 4 fold at 24 h and lowered at 48 h whereas a steady rise was seen in the FXIII-DR. FDP levels in GSR animals were significantly elevated at 24 h and further increased at 48 h but only slightly elevated in the FXIII-DR. Examination of the LSR tissues after 48 h showed an acute onset of progressive cutaneous vascular thrombosis, purpura, and secondary hemorrhagic necrosis whereas neither fibrin deposit nor necrosis of tissue were detected in FXIII-DR despite of an early edema formation. Fibrinogen levels were also increased two fold at 24 h but returned to basal levels at 48 h in control LSR animals but not affected at all in FXIII-DR. These results suggest that during the severe inflammatory conditions such as sepsis, the fibrinolytic system is functionally sufficient to dissipate the pathogenic accumulation of disseminated intravascular clots and exudated fibrin clots if those clots were prevented from getting crosslinked in plasma.

Animals↗
PubMed2001

Systemic, but not intrathecal, ketamine produces preemptive analgesia in the rat formalin model.

BACKGROUND: We investigated the antinociceptive effects of pre- or posttreatment of intrathecal or intravenous ketamine on formalin-induced pain behaviors. METHODS: Rats were divided into 4 groups of 7 rats each and 2 control groups (saline). Rats received ketamine 1 mg/kg intrathecally (i.t.) through a catheter either 15 min before or 5 min after formalin. In the other groups, they received ketamine 1 mg/kg intravenously (i.v.) through a catheter either 1 min before or 5 min after the formalin. Pain related behavior was quantified by counting the incidence of flinching of the injected paw for 60 min. Formalin induced a biphasic fliching (phase 1, 0-5 min; phase 2, 10-60 min after formalin injection) of injected paw. The inter-group (control, pre, and posttreatment groups) comparisons were performed separately for route of administration (i.t. or i.v.) and phase 1 and 2 using one-way ANOVA and Tukey test. RESULTS: Flinches of phase 1 were not different among the three i.t. groups. The total flinches of phase 2 were reduced by posttreatment with i.t. ketamine (P < 0.05); In contrast, i.v. ketamine was effective only when given as a pretreatment. Flinches of phase 1 and 2 were reduced by pretreatment with i.v. ketamine (P < 0.05). CONCLUSIONS: Intrathecal ketamine was an analgesic even when administered as a posttreatment, whereas intravenous ketamine produced effective preemption only when given as a pretreatment.

Analgesia↗
PubMed2001

Congenital generalized lipodystrophy in a 4-month-old infant.

Congenital generalized lipodystrophy (CGL, Berardinelli-Seip syndrome) is a rare autosomal recessive disorder with a clinical presentation of paucity of adipose tissue, muscular hypertrophy, organomegaly, and insulin-resistant diabetes. A 4-month-old Taiwanese female infant had hepatosplenomegaly and low body weight gain despite a voracious appetite. Hypermetabolism, hyperhidrosis, loss of subcutaneous fat, muscular hypertrophy, acanthosis nigricans, hypertrichosis, and marked hypertriglyceridemia were also noted. Liver histology revealed fatty change and portal-to-portal bridging fibrosis. Clinical features, serum biochemistry, and liver histology were compatible with the diagnosis of CGL. She was given a special diet characterized by calorie restriction and partial substitution of long-chain triglycerides with medium-chain triglycerides. The serum triglyceride concentration subsequently decreased. This present case suggests that extensive fatty infiltration and subsequent cirrhosis of the liver may be the earliest complication of CGL.

Female↗
PubMed2001

Superior mesenteric artery syndrome associated with hereditary motor and sensory neuropathy type II--a case report.

A 14-year-old girl with superior mesenteric artery (SMA) syndrome associated with hereditary motor and sensory neuropathy (HMSN) type II is reported. The initial presentations of HMSN type II were developmental delay and gait disturbance at 2 years of age. All deep tendon reflexes were absent. Nerve conduction velocities and left sural nerve biopsy all revealed axonal changes. Recently, she suffered from intermittent bilious vomiting and epigastralgia for 6 months. That caused body weight loss from 40 kg to 28 kg. Abdominal echography showed narrowed superior mesenteric artery angle. Upper gastrointestinal series revealed obstruction of third portion of duodenum. Accordingly, SMA syndrome was diagnosed. To the best of our knowledge, this case is the first report of SMA with HMSN type II in the world. When a child with chronic neurological disease presents with intermittent vomiting, SMA should be considered as a disease entity of differential diagnosis.

Adolescent↗
PubMed2001

Clavaspirin, an antibacterial and haemolytic peptide from Styela clava.

We cloned the precursor of a novel peptide from a cDNA library prepared from pharyngeal tissues of the tunicate, Styela clava. Its sequence predicted a histidine-rich, amidated 23-residue peptide (FLRF(IG)SVIHGIGHLVHHIGVAL-NH2) that we named clavaspirin. A synthetic clavaspirin was prepared and it was found that it killed Gram-positive and Gram-negative bacteria, permeabilized the outer and inner membranes of Escherichia coli, lysed phosphatidylglycerol (POPG) liposomes, and was potently haemolytic towards human and bovine erythrocytes. Each of these activities was performed more effectively at an acidic pH. Circular dichroism measurements of synthetic clavaspirin revealed a largely alpha-helical structure and polarized and residue-specific FTIR spectrometry showed that its association with phospholipid membranes was influenced by pH. Peptides such as clavaspirin may equip tunicate haemocytes to mediate cytotoxicity and participate in antimicrobial defence.

Amino Acid Sequence↗
PubMed2000

Cytoplasmic dynein ATPase activity is regulated by dynactin-dependent phosphorylation.

Cytoplasmic dynein is a microtubule-associated motor that utilizes ATP hydrolysis to conduct minus-end directed transport of various organelles. Dynactin is a multisubunit complex that has been proposed to both link dynein with cargo and activate dynein motor function. The mechanisms by which dynactin regulates dynein activity are not clear. In this study, we examine the role of dynactin in regulating dynein ATPase activity. We show that dynein-microtubule binding and ATP-dependent release of dynein from microtubules are reduced in dynactin null mutants, Deltaro-3 (p150(Glued)) and Deltaro-4 (Arp1), relative to wild-type. The dynein-microtubule binding activity, but not the ATP-dependent release of dynein from microtubules, is restored by in vitro mixing of extracts from dynein and dynactin mutants. Dynein produced in a Deltaro-3 mutant has approximately 8-fold reduced ATPase activity relative to dynein isolated from wild-type. However, dynein ATPase activity from wild-type is not reduced when dynactin is separated from dynein, suggesting that dynein produced in a dynactin mutant is inactivated. Treatment of dynein isolated from the Deltaro-3 mutant with lambda protein phosphatase restores the ATPase activity to near wild-type levels. The reduced dynein ATPase activity observed in dynactin null mutants is mainly due to altered affinity for ATP. Radiolabeling experiments revealed that low molecular mass proteins, particularly 20- and 8-kDa proteins, that immunoprecipitate with dynein heavy chain are hyperphosphorylated in the dynactin mutant and dephosphorylated upon lambda protein phosphatase treatment. The results suggest that cytoplasmic dynein ATPase activity is regulated by dynactin-dependent phosphorylation of dynein light chains.

Adenosine Triphosphate↗
PubMed2000

Gene expression of flap endonuclease-1 during cell proliferation and differentiation.

It has been shown that flap endonuclease-1 (FEN-1), a structure-specific nuclease, acts on the removal of RNA primers during Okazaki fragment maturation in DNA synthesis. To study whether the gene expression of FEN-1 is inducible during cell proliferation, we analyzed the FEN-1 mRNA levels in actively growing cells and non-growing cells. The gene expression of FEN-1 was higher in mitotic cells than in resting cells, and was markedly decreased, especially, when terminal differentiation was induced in promyelocytic leukemia cells (HL-60 cells). The decline correlated substantially with the ceasing of DNA synthesis. In the examination of tissue-specific gene expression, the human testis, spleen, thymus and mucosal lining of colon tissues expressed this gene actively, whereas the prostate, ovary, small intestine and peripheral blood leukocyte hardly expressed it. In addition, FEN-1 was co-localized with the proliferating cell nuclear antigen (PCNA) in young rat kidney according to immunohistochemistry. These findings suggest that FEN-1 gene expression is inducible during cell proliferation for DNA synthesis, and is down-regulated during cell differentiation.

Animals↗
PubMed2000

cDNA cloning and antibacterial activities of cecropin D-like peptides from Agrius convolvuli.

We have characterized full-length cDNAs encoding two isoforms of agriusin, cecropin D-like antibacterial peptide, present in the hemolymph of the immunized Agrius convolvuli larvae. The cloned cDNAs of agriusins 1 and 2 contain 331 and 329 bp, respectively. The nucleotide sequencing of cDNAs showed that they encode 62 amino acids, whose mature portion was deduced to consist of 38 amino acid residues with over 94% sequence identity. In the sequence homology search, mature agriusin 1 showed over 86 and 71% amino acid sequence homology with bactericidin 4 from Manduca sexta and cecropin D from Hyalophora cecropia, respectively. Since it was demonstrated from the deduced amino acid sequences that the C-terminal residues of agriusins are followed by a Gly residue, two types of synthetic agriusin 1 (syn-agriusin 1 amide and acid) were prepared to verify if natural agriusin 1 is C-terminally amidated. From acid-urea PAGE and reversed phase HPLC profiles to compare two synthetic peptides, we could confirm that the C-terminal amino acid residue of natural agriusin 1, like several cecropins so far identified, is amidated. Finally, our antibacterial assay performed with two syn-agriusins 1 revealed that there is little difference between antibacterial activities of both peptides against Gram-positive and Gram-negative bacteria.

Amino Acid Sequence↗
PubMed2000

A Neurospora crassa Arp1 mutation affecting cytoplasmic dynein and dynactin localization.

Of the actin-related proteins, Arp1 is the most similar to conventional actin, and functions solely as a component of the multisubunit complex dynactin. Dynactin has been identified as an activator of the microtubule-associated motor cytoplasmic dynein. The role of Arp1 within dynactin is two-fold: (1) it serves as a structural scaffold protein for other dynactin subunits; and (2) it has been proposed to link dynactin, and thereby dynein, with membranous cargo via interaction with spectrin. Using the filamentous fungus Neurospora crassa, we have identified genes encoding subunits of cytoplasmic dynein and dynactin. In this study, we describe a genetic screen for N. crassa Arp1 (ro-4) mutants that are defective for dynactin function. We report that the ro-4(E8) mutant is unusual in that it shows alterations in the localization of cytoplasmic dynein and dynactin and in microtubule organization. In the mutant, dynein/dynactin complexes co-localize with bundled microtubules at hyphal tips. Given that dynein transports membranous cargo from hyphal tips to distal regions, the cytoplasmic dynein and dynactin complexes that accumulate along microtubule tracts at hyphal tips in the ro-4(E8) mutant may have either reduced motor activity or be delayed for activation of motor activity following cargo binding.

Actins↗
PubMed2000

Wegener's granulomatosis presenting as mediastinal soft tissue mass invading the tracheal wall.

Wegener's granulomatosis (WG) is a clinicopathologic entity of unknown cause characterised by a necrotising granulomatous vasculitis affecting multiple organs, especially the upper and lower respiratory tracts, lung and kidney. The lung is the most frequently, and sometimes the only involved organ. Single or multiple nodules, with or without cavitation, are the most common pulmonary manifestations in WG, but mediastinal involvement is atypical. The sole tracheal involvement is rare and hilar and mediastinal involvement has been thought not to be part of the clinical feature. We experienced a rare case of WG presenting as paratracheal mediastinal lesions with tracheal wall invasion, which responded dramatically to corticosteroid treatment. We present this case with a review of the literature.

Adult↗
PubMed2000

Two approaches to isolate cytoplasmic dynein ATPase from Neurospora crassa.

Cytoplasmic dynein is a force-producing enzyme that, in association with dynactin, conducts minus-end directed transport of various organelles along microtubules. Biochemical analyses of cytoplasmic dynein and dynactin have been conducted primarily in vertebrate systems, whereas genetic analyses have been explored mainly in yeast and the filamentous fungi. To provide a complementary biochemical approach for the study of fungal dynein, we isolated/partially purified cytoplasmic dynein ATPase from the filamentous fungus Neurospora crassa. N. crassa dynein was partially purified by slightly modifying the existing procedures, described for mammalian cytoplasmic dynein that uses dynein-microtubule binding, followed by release with ATP and sucrose gradient fractionation. A novel approach was also used to isolate dynein-specific ATPase by gel filtration (Sepharose CL-4B). The K(m), ATP obtained by isolating dynein ATPase using gel filtration was similar to that obtained by using conventional method, suggests that contaminant proteins do not interfere with the dynein ATPase activity. Like vertebrate dynein, N. crassa dynein is a general NTPase with highest activity toward ATP, and only the ATPase activity is stimulated by microtubules. The K(m), ATP for N. crassa cytoplasmic dynein is 10- to 15-fold higher than that of the vertebrate enzyme.

Adenosine Triphosphate↗
PubMed2000

Antibacterial properties and partial cDNA sequences of cecropin-like antibacterial peptides from the common cutworm, Spodoptera litura.

The antibacterial properties and cDNA sequences of two types of antibacterial peptides from the haemolymph of immunized common cutworm, Spodoptera litura larvae, were determined. Since the primary structures of peptides deduced from cDNA sequences showed significant homologies to cecropins A and B, they were named as Spodoptera cecropins A and B. Spodoptera cecropins were broadly effective against Gram-positive and negative bacteria. They also retained antibacterial activities in all conditions tested (at pH 5.6-8.0 and in the presence of 50-150 mM NaCl) that was adapted to confirm the antibacterial properties of Spodoptera cecropins. These results indicate that the change of pH and the increase of salt concentration in the media do not influence the activities of Spodoptera cecropins. For the reverse transcription (RT)-polymerase chain reaction (PCR) to obtain the complete primary sequence, the primer designed according to the conserved region of the cecropin leader sequences was used, which was determined by the comparison of the cDNA sequences of known cecropins. The results from RT-PCR presented that the partial cDNAs of Spodoptera cecropins A and B encode 57 and 58 amino acids, including the sequences of mature peptides, respectively. In addition, Northern blot analysis with (32)P-labeled PCR product coding for Spodoptera cecropin A revealed that Spodoptera cecropin genes are expressed in immunized fat body, but not in normal fat body.

Amino Acid Sequence↗