Biomedical subjects

H S Cho

Publications and source records attributed to H S Cho.

At least 19 recordsLinked to original sources

PubMed2007

Pharmacokinetics of a new long acting endectocide formulation containing 2.25% ivermectin and 1.25% abamectin in cattle.

The objective of this study was to determine the kinetic parameters of a new formulation that contained 2.25% ivermectin combined with 1.25% abamectin in bovine plasma. The results for 2.25% ivermectin: Cmax (37.11 ng/mL +/- 7.42), Tmax (16 days +/- 5.29), T(1/2) (44.62 days +/- 53.89), AUC (928.2 ng x day/mL +/- 153.83) and MRT (36.73 days +/- 33.64), and for 1.25% abamectin: Cmax (28.70 ng/mL +/- 9.54), Tmax (14 days +/- 4.04), T(1/2) (15.40 days +/- 11.43), AUC (618.05 ng x day/mL +/- 80.27) and MRT (20.79 days +/- 8.43) suggest that this combination of 2.25% ivermectin + 1.25% abamectin possesses properties that give this pharmaceutical formula a longer activity time than two of the commercial products tested (1% ivermectin and 1% abamectin), and showed similarity to 3.15% ivermectin.

Animals↗

PubMed2006

Primary haemangiopericytoma in the pelvic cavity of a dog.

A 9-year-old female Yorkshire terrier with lameness of the hind leg was examined at the local animal hospital in Gwangju, Republic of Korea on March, 2004. The radiological findings revealed a mass between the urinary bladder and cervix of the uterus. The encapsulated pelvic mass, measuring 4.0 x 3.0 x 2.5 cm was surgically removed. Grossly, the mass was white and firm and microscopically showed a perivascular whorled pattern of spindle cells. By immunohistochemistry, tumour cells tested positive for vimentin and alpha-smooth muscle actin, and negative for desmin, S-100, lysozyme and cytokeratin. The tumour was diagnosed both histologically and immunohistochemically as a haemangiopericytoma. There were no signs of recurrence within 12 months after surgery. This is the first case report of a haemangiopericytoma in the pelvic cavity of a dog.

Animals↗

PubMed2006

Malignant schwannoma in an American buffalo (Bison bison bison).

A case of a malignant schwannoma in a 20-year-old male American buffalo (Bison bison bison) from the Grand Park Zoo, Gyeonggi Province, Republic of Korea is reported. The animal showed no apparent clinical signs before death except for wound on the neck. Grossly, neoplastic nodules of various sizes were observed on the skin, lung, heart, liver, stomach, mesentery and kidney. Histologically, the neoplastic nodules were composed of fusiform cells that formed multidirectional bundles. The tumour cells were arranged in interlacing bands and bundles. The nuclei were atypical, hyperchromatic, with blunt or round ends. In addition, few mitotic figures were observed in the skin, lung, heart, liver, stomach, intestine and kidney. Several immunohistochemical stains, e.g. vimentin, cytokeratin (CK), smooth muscle actin (SMA), S-100 and HMB45, were used in an attempt to differentially diagnose the tumour. The neoplastic cells tested positive to S-100, but negative to vimentin, CK, SMA and HMB45. Based on the above findings, this case was diagnosed as a malignant schwannoma. To the best of our knowledge, this is the first report of a schwannoma in an American buffalo (B. b. bison).

Animals↗

PubMed2006

Endometrial polyp in an African wild dog (Lycaon pictus).

An 8-year-old female African wild dog (Lycaon pictus) from a zoo in Gyeonggi province, Republic of Korea presented with a 3.0 x 2.0 x 2.5 cm in size, smooth-surfaced, solitary pedunculated mass protruding into the uterine lumen. Microscopically, the mass was covered with epithelium, contained endometrial gland tissue, and was dilated in the vascularised stroma. Within the mass, there was extensive diffuse haemorrhage with several blood vessels apparently plugged with fibrin. At the base of the mass, the spaces lined with epithelium near the attachment of the stalk were interpreted to be glandular structures. There were segments of cuboidal epithelium found on the surface of the mass, which was similar to the lining the uterus. A diagnosis of an endometrial polyp was made based on the gross and histology findings. This is the first case report of a spontaneous endometrial polyp in an African wild dog.

Animals↗

PubMed2006

Serodiagnostic comparison between two methods, ELISA and surface plasmon resonance for the detection of antibody titres of Mycoplasma hyopneumoniae.

A protein chip based on surface plasmon resonance (SPR) was developed for measuring the Mycoplasma hyopneumoniae antibody titres using a recombinant 30-kDa fragment of P97 adhesin as an antigen. The diagnostic potential of this SPR assay, for detecting the antibody titres to the M. hyopneumoniae 30-kDa protein, was compared with that of conventional ELISA using 70 pig serum samples taken from six pig farms. The SPR assay was found to be highly specific and sensitive. Moreover, there was a strong positive correlation between the SPR and ELISA titres (n = 70, r = 0.898, P < 0.01). Therefore, this recombinant 30-kDa protein can be used as an antigen for serological studies, and the SPR, which is a label-free method, is expected to be a valuable and reproducible tool in the serodiagnosis of M. hyopneumoniae infection.

Animals↗

PubMed2006

Detection and molecular characterization of porcine enteric calicivirus in Korea, genetically related to sapoviruses.

Porcine enteric calicivirus (PECV) shares morphological and genetical similarities with Sapoviruses (SVs), which are the leading cause of epidemic, non-bacterial gastroenteritis in children worldwide. The aim of this study was to identify the prevalence of PECV infection in pig farms in Korea, and to compare the evolutionary inter-relationships between Korean PECVs and other caliciviruses. Among 102 diarrhoeic faecal samples of sucking (n = 50) and weaned (n = 52) piglets from 31 different farms in Korea, five samples (4.9%) were detected positive by reverse-transcriptase polymerase chain reaction (PCR), but nine (8.8%) by nested-PCR. Furthermore, we found that Korean PECVs are closely related to SVs.

Animals↗

PubMed2005

Development and characterization of human constitutive proteasome and immunoproteasome subunit-specific monoclonal antibodies.

Delta (Y), MB1 (X), and Z are the three catalytic beta-subunits located in the inner rings of the constitutive proteasome, an intracellular multicatalytic complex responsible for the generation of peptides presented by human leukocyte antigen (HLA) class I antigens to T cells. When cells are incubated with interferon-gamma, delta (Y), MB1 (X), and Z are replaced by LMP2, LMP7, and LMP10, respectively, leading to the expression of immunoproteasome which generates peptides with increased affinity for HLA class I antigens. The characterization of the expression of constitutive proteasome and immunoproteasome subunits in cells, normal tissues, and malignant lesions has been hampered by the lack or limited availability of constitutive proteasome and immunoproteasome subunit-specific monoclonal antibodies (mAbs), which are suitable for immunohistochemical staining. To overcome this limitation, we generated human delta (Y), MB1 (X), Z, LMP2, LMP7, and LMP10-specific mAb-secreting hybridomas from BALB/c mice immunized with peptides and recombinant fusion proteins. The mAbs SY-5, SJJ-3, NB-1, SY-1, HB-2, and TO-7 were shown to be specific for delta (Y), MB1 (X), Z, LMP2, LMP7, and LMP10, respectively, as they react specifically with the corresponding molecules when tested with a human B lymphoid LG2 cell lysate in Western blotting and with the peptide derived from each molecule in enzyme-linked immunosorbent assay. The reactivity of the six mAbs with the corresponding intracellular antigens resulted in intracellular staining when the mAbs were tested with microwave-treated and saponin-permeabilized cells in indirect immunofluorescence and with formalin-fixed, paraffin-embedded tissue sections in immunohistochemical reactions. These results suggest that the constitutive proteasome and immunoproteasome subunit-specific mAbs we have developed are useful probes to characterize the expression of proteasome subunits in normal tissues and in pathological lesions.

Animals↗

PubMed2005

Detection of canine distemper virus in blood samples by reverse transcription loop-mediated isothermal amplification.

Reverse transcription loop-mediated isothermal amplification (RT-LAMP) was used to detect canine distemper virus (CDV) genomic RNA. A set of four primers, two outer and two inner, were designed from CDV genomic RNA targeting the nucleocapsid protein gene. The optimal reaction time and temperature for LAMP were determined to be 60 min at 65 degrees C. The relative sensitivity and specificity of RT-LAMP was found to be 100% and 93.3%, respectively, based on 50 canine blood samples and using RT-PCR as the gold standard. The detection limit of the RT-LAMP method was 100 times lower than with RT-PCR (10-1TCID50 ml(-1) versus 10TCID50 ml(-1)). In addition to the advantage resulting from the visual detection of the end-product, the LAMP method is fast, requiring only 1 h to complete the assay. The LAMP method is a viable alternative to RT-PCR for diagnosing CDV infection in dogs. The LAMP method might be useful as an on site diagnostic assay for detecting CDV.

Animals↗

PubMed2003

Expression of an artificial polypeptide with a repeated tripeptide glutamyl-tryptophanyl-lysine in Saccharomyces cerevisiae.

AIMS: Artificial genes, which encode 48 or 64 repeats of a tripeptide, glutamyl-tryptophanyl-lysine have been cloned to the yeast expression vector pAM82 containing the PHO5 promoter and expressed in Saccharomyces cerevisiae AH22. METHODS AND RESULTS: When the yeast cells harbouring recombinant plasmids pALTG6-2 and pALTG4-4 were derepressed in Burkholder minimal medium (Toh-e, A., Ueda, Y., Kakimoto, S.I. and Oshima, Y. (1973) Journal of Bacteriology113, 727-738) containing low phosphate (0.03 g l-1 KH2PO4 and 1.5 g l-1 KCl), the expression was the highest after 24 h induction and the artificial polypeptides were synthesized to about 10% (pALTG6-2) and 14% (pALTG4-4) of the total cell protein. CONCLUSIONS: The artificial polypeptides produced in yeast were made to react with the rabbit antiserum against the polypeptide purified from Escherichia coli and found only in the pellet fraction of cell lysates, indicating the formation of inclusion body. Artificial polypeptide consisting of Glu-Trp-Lys may be useful as partial supplement in food and feeds. SIGNIFICANCE AND IMPACT OF THE STUDY: The production of single cell enriched with homopolymers of an essential amino acid in yeast might be an important tool of supplementing cereal diets and feed grain rations and could be used as means for improvement of the amino acid profile of single cell protein and production of pharmaceutical peptides.

Amino Acids, Essential↗

PubMed2002

Offspring resulting from direct transfer of cryopreserved bovine embryos produced in vitro in chemically defined media.

The present work was designed to study the in vitro and in vivo viability, as assessed by blastocyst formation, pregnancy rate and term delivery of bovine embryos produced under completely defined conditions with or without insulin-like growth factor I (IGF-I) following direct transfer after cryopreservation. Slaughterhouse-derived bovine oocytes were matured for 24h, fertilized with frozen-thawed spermatozoa and cultured in vitro under completely defined conditions with or without exposure to IGF-I (5 ng/ml). Only those embryos classified as excellent or good quality blastocysts were frozen. Each blastocyst was individually loaded into a straw, seeded and pre-cooled to -7 degrees C. After 10 min at -7 degrees C straws were frozen further to -30 degrees C at a rate of 0.3 degrees C/min and then plunged into liquid nitrogen. Synchronized recipient cows received one embryo in the horn ipsilateral to the corpus luteum (CL). Pregnancies were diagnosed by ultrasonography 35-45 days after embryo transfer (ET). IGF-I failed to improve cleavage rate, as well as blastocyst production, when added during in vitro culture (IVC). Pregnancy outcome was not significantly improved in cows that received an IGF-I-treated embryo compared with controls (4/10 versus 3/10, respectively). Five out of six calves delivered to date were born alive and healthy. We have shown that it is possible to obtain healthy live offspring from frozen-thawed embryos produced under chemically defined conditions after direct transfer.

Animals↗

PubMed2002

A simplified cardiopulmonary bypass technique for animal experiments on implantable ventricular assist devices.

We have developed and report on a simplified cardiopulmonary bypass technique for experiments on implantable ventricular assist devices in calves. We used an electromechanical implantable ventricular assist device with a double cylindrical cam in three calves. Cannulas for the ventricular assist system were designed to be inserted between the left atrium and the descending aorta. We used the outflow cannula of the ventricular assist device, anastomosed to the descending aorta, as a temporary arterial return route for the cardiopulmonary bypass. A cannula for venous drainage was iserted into the right ventricle through the pulmonary artery. There were no problems related to the procedure and the cardiopulmonary bypass was succesful. In conclusion, this simplified cardiopulmonary bypass technique without neck incision in calves, as used in developmental work involving implantable ventricular assist devices, can be reliably performed.

Animals↗

PubMed2001

A novel class of highly potent, selective, and non-peptidic inhibitor of Ras farnesyltransferase (FTase).

Design, synthesis and structure-activity relationship of a class of aryl pyrroles as farnesyltransferase inhibitors are described. In vitro and in vivo evaluation of a panel of these inhibitors led to identification of 2 (LB42908) as a highly potent (IC(50)=0.9 nM against H-Ras and 2.4 nM against K-Ras) antitumor agent that is currently undergoing preclinical studies.

Alkyl and Aryl Transferases↗

PubMed2001

Non-apoptotic signaling pathways activated by soluble Fas ligand in serum-starved human fibroblasts. Mitogen-activated protein kinases and NF-kappaB-dependent gene expression.

Many Fas-expressing cells do not undergo cell death upon Fas stimulation. In the normal human diploid cell line GM6112, the addition of soluble Fas ligand (sFasL) leads to morphological signs of cell death in less than 1% of cells. Treatment of serum-starved GM6112 fibroblasts with sFasL resulted in a rapid and transient phosphorylation of ERK1/2 without a significant increase in JNK and p38 activities. Unless co-treated with the protein synthesis inhibitor anisomycin, sFasL did not show gene-inducing activity in cells maintained in complete medium. However, when cells were serum-starved for 4 days, treatment with sFasL alone induced interleukin-6 gene expression and, less strongly, interleukin-8 gene expression. Sensitization of the gene-inducing activity by serum starvation correlated with NF-kappaB activation by sFasL. Furthermore, we found that the expression of FADD and caspase-8 was significantly reduced in serum-starved cells, whereas the level of cFLIP remained unchanged. Transfection of GM6112 cells with the antisense caspase-8 expression construct sensitized cells toward sFasL-induced NF-kappaB-dependent reporter activation. Our results support the notion that a change in the ratio of cFLIP and caspase-8 may be responsible for turning on the Fas-activated NF-kappaB pathway, which otherwise is supplanted by the death-inducing pathway.

Animals↗

PubMed2001

Pathogenic effects of D23N Iowa mutant amyloid beta -protein.

Cerebral amyloid beta-protein angiopathy (CAA) is a key pathological feature of patients with Alzheimer's disease and certain related disorders. In these conditions the CAA is characterized by the deposition of Abeta within the cerebral vessel wall and, in severe cases, hemorrhagic stroke. Several mutations have been identified within the Abeta region of the Abeta protein precursor (AbetaPP) gene that appear to enhance the severity of CAA. We recently described a new mutation within the Abeta region (D23N) of AbetaPP that is associated with severe CAA in an Iowa kindred (Grabowski, T. J., Cho, H. S., Vonsattel, J. P. G., Rebeck, G. W., and Greenberg, S. M. (2001) Ann. Neurol. 49, 697-705). In the present study, we investigated the effect of this new D23N mutation on the processing of AbetaPP and the pathogenic properties of Abeta. Neither the D23N Iowa mutation nor the E22Q Dutch mutation affected the amyloidogenic processing of AbetaPP expressed in H4 cells. The A21G Flemish mutation, in contrast, resulted in a 2.3-fold increase in secreted Abeta peptide. We also tested synthetic wild-type and mutant Abeta40 peptides for fibrillogenesis and toxicity toward cultured human cerebrovascular smooth muscle (HCSM) cells. The E22Q Dutch, D23N Iowa, and E22Q,D23N Dutch/Iowa double mutant Abeta40 peptides rapidly assembled in solution to form fibrils, whereas wild-type and A21G Flemish Abeta40 peptides exhibited little fibril formation. Similarly, the E22Q Dutch and D23N Iowa Abeta40 peptides were found to induce robust pathologic responses in cultured HCSM cells, including elevated levels of cell-associated AbetaPP, proteolytic breakdown of smooth muscle cell alpha-actin, and cell death. Double mutant E22Q,D23N Dutch/Iowa Abeta40 was more potent than either single mutant form of Abeta in causing pathologic responses in HCSM cells. These data suggest that the different CAA mutations in AbetaPP may exert their pathogenic effects through different mechanisms. Whereas the A21G Flemish mutation appears to enhance Abeta production, the E22Q Dutch and D23N Iowa mutations enhance fibrillogenesis and the pathogenicity of Abeta toward HCSM cells.

Amino Acid Sequence↗

PubMed2001

A novel dual-specificity protein kinase targeted to the chloroplast in tobacco.

The NtDSK1 cDNA encoding a novel chloroplast-targeted protein kinase was identified in Nicotiana tabacum. It contains the kinase domain at the C-terminus and a putative regulatory domain at the N-terminus. The recombinant NtDSK1 underwent autophosphorylation of serine, threonine, and tyrosine residues, indicating that NtDSK1 encodes a functional dual-specificity protein kinase. The NtDSK1-green fluorescent protein fusion protein was targeted to chloroplasts. Furthermore, the NtDSK1 protein was immunodetected in chloroplast fractions isolated from tobacco seedlings. The NtDSK1 mRNA expression was developmentally regulated in different tissues, including anthers and germinating seeds, and strongly stimulated by gibberellin. The mRNA was rapidly light responsive during seedling growth. NtDSK1 may play a role in a light-regulated signaling process in tobacco.

Chloroplasts↗

PubMed2001

Molecular characterization of the NeIF2Bbeta gene encoding a putative eIF2B beta-subunit in Nicotiana tabacum.

The NeIF2Bbeta cDNA encoding beta-subunit of the translation initiation factor 2B (eIF2B-beta) was identified from Nicotiana tabacum through protein interaction with PRK1, a reproductive-organ-specific receptor-like kinase (Park et al., 2000). The eIF2B is a guanine nucleotide-exchange protein that consists of five subunits, which function in the regulation of translation in eukaryotic cells. The NeIF2Bbeta that shows a high homology in the amino acid sequence with other beta-subunits also exhibits sequence similarity to a and delta subunits of eIF2B from yeast and animals. The NeIF2Bbeta gene was expressed in all of the tissues examined, but the mRNA level was higher in reproductive tissues than in vegetative tissues. During anther development, the NeIF2Bbeta mRNA was detected in all stages with a slightly higher level in the earliest stage. The NeIF2Bbeta-GFP fusion protein was mainly localized in the cytosol.

Cytosol↗

PubMed2001

Crystal structure of activated CheY. Comparison with other activated receiver domains.

The crystal structure of BeF(3)(-)-activated CheY, with manganese in the magnesium binding site, was determined at 2.4-A resolution. BeF(3)(-) bonds to Asp(57), the normal site of phosphorylation, forming a hydrogen bond and salt bridge with Thr(87) and Lys(109), respectively. The six coordination sites for manganese are satisfied by a fluorine of BeF(3)(-), the side chain oxygens of Asp(13) and Asp(57), the carbonyl oxygen of Asn(59), and two water molecules. All of the active site interactions seen for BeF(3)(-)-CheY are also observed in P-Spo0A(r). Thus, BeF(3)(-) activates CheY as well as other receiver domains by mimicking both the tetrahedral geometry and electrostatic potential of a phosphoryl group. The aromatic ring of Tyr(106) is found buried within a hydrophobic pocket formed by beta-strand beta4 and helix H4. The tyrosine side chain is stabilized in this conformation by a hydrogen bond between the hydroxyl group and the backbone carbonyl oxygen of Glu(89). This hydrogen bond appears to stabilize the active conformation of the beta4/H4 loop. Comparison of the backbone coordinates for the active and inactive states of CheY reveals that only modest changes occur upon activation, except in the loops, with the largest changes occurring in the beta4/H4 loop. This region is known to be conformationally flexible in inactive CheY and is part of the surface used by activated CheY for binding its target, FliM. The pattern of activation-induced backbone coordinate changes is similar to that seen in FixJ(r). A common feature in the active sites of BeF(3)(-)-CheY, P-Spo0A(r), P-FixJ(r), and phosphono-CheY is a salt bridge between Lys(109) Nzeta and the phosphate or its equivalent, beryllofluoride. This suggests that, in addition to the concerted movements of Thr(87) and Tyr(106) (Thr-Tyr coupling), formation of the Lys(109)-PO(3)(-) salt bridge is directly involved in the activation of receiver domains generally.

Bacterial Proteins↗

PubMed2001

Photophysical properties of long rodlike meso-meso-linked zinc(II) porphyrins investigated by time-resolved laser spectroscopic methods.

The molecular design of directly meso-meso-linked porphyrin arrays as a new model of light-harvesting antenna as well as a molecular photonic wire was envisaged to bring the porphyrin units closer for rapid energy transfer. For this purpose, zinc(II) 5,15-bis(3,5-bis(octyloxy)phenyl)porphyrin (Z1) and its directly meso-meso-linked porphyrin arrays up to Z128 (Zn, n represents the number of porphyrins) were synthesized. The absorption spectra of these porphyrin arrays change in a systematic manner with an increase in the number of porphyrins; the high-energy Soret bands remain at nearly the same wavelength (413-414 nm), while the low-energy exciton split Soret bands are gradually red-shifted, resulting in a progressive increase in the exciton splitting energy. The exciton splitting is nicely correlated with the values of cos[pi/(N + 1)] according to Kasha's exciton coupling theory, providing a value of 4250 cm(-1) for the exciton coupling energy in the S(2) state. The increasing red-shifts for the Q-bands are rather modest. The fluorescence excitation anisotropy spectra of the porphyrin arrays show that the photoexcitation of the high-energy Soret bands exhibits a large angle difference between absorption and emission dipoles in contrast with the photoexcitation of the low-energy exciton split Soret and Q-bands. This result indicates that the high-energy Soret bands are characteristic of the summation of the individual monomeric transitions with its overall dipole moment deviated from the array chain direction, while the low-energy Soret bands result from the exciton splitting between the monomeric transition dipoles in line with the array chain direction. From the fluorescence quantum yields and fluorescence lifetime measurements, the radiative coherent length was estimated to be 6-8 porphyrin units in the porphyrin arrays. Ultrafast fluorescence decay measurements show that the S(2) --> S(1) internal conversion process occurs in less than 1 ps in the porphyrin arrays due to the existence of exciton split band as a ladder-type deactivation channel, while this process is relatively slow in Z1 (approximately 1.6 ps). The rate of this process seems to follow the energy gap law, which is mainly determined by the energy gap between the two Soret bands of the porphyrin arrays.

Journal Article↗