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Biomedical subjects

H J Cho

Publications and source records attributed to H J Cho.

At least 55 records · Page 3Linked to original sources
PubMed1998

Web based 3-D medical image visualization on the PC.

With the recent advance of Web and its associated technologies, information sharing on distribute computing environments has gained a great amount of attention from many researchers in many application areas, such as medicine, engineering, and business. One basic requirement of distributed medical consultation systems is that geographically dispersed, disparate participants are allowed to exchange information readily with each other. Such software also needs to be supported on a broad range of computer platforms to increase the softwares accessibility. In this paper, the development of world-wide-web based medical consultation system for radiology imaging is addressed to provide platform independence and greater accessibility. The system supports sharing of 3-dimensional objects. We use VRML (Virtual Reality Modeling Language), which is the defacto standard in 3-D modeling on the Web. 3-D objects are reconstructed from CT or MRI volume data using a VRML format, which can be viewed and manipulated easily in Web-browsers with a VRML plug-in. A Marching cubes method is used in the transformation of scanned volume data sets to polygonal surfaces of VRML. A decimation algorithm is adopted to reduce the number of meshes in the resulting VRML file. 3-D volume data are often very large in size, hence loading the data on PC level computers requires a significant reduction of the size of the data, while minimizing the loss of the original shape information. This is also important to decrease network delays. A prototype system has been implemented (http://cybernet5.snu.ac.kr/-cyber/mrivrml .html), and several sessions of experiments are carried out.

Algorithms↗
PubMed1997

Changes in the alpha 2-adrenergic receptor subtypes gene expression in rat dorsal root ganglion in an experimental model of neuropathic pain.

We examined changes in expression of genes coding for alpha 2-AR subtypes in the dorsal root ganglion (DRG) in a rat model (spinal nerve ligation) or neuropathic pain. The present study demonstrates that the majority of DRG neurons express alpha 2C-AR mRNA and a small proportion of neurons express alpha 2A-AR mRNA, while few neurons express alpha 2B-AR mRNA in non-operated animals. In addition, alpha 2C- and alpha 2A mRNA levels in the DRG showed a significant decrease and increase, respectively in ligated animals. These findings suggest that alpha 2A- and alpha 2C-ARs in the DRG may play an important role in generating sympathetically maintained neuropathic pain.

Animals↗
PubMed1997

Increased brain-derived neurotrophic factor immunoreactivity in rat dorsal root ganglia and spinal cord following peripheral inflammation.

Our recent study showed that peripheral inflammation induced an increased expression of brain-derived neurotrophic factor (BDNF) mRNA which was mediated by nerve growth factor (NGF) in the dorsal root ganglion (DRG). In the present study, we evaluated the change of BDNF immunoreactivity in the DRG and spinal cord following peripheral inflammation by means of immunohistochemistry. Significant increases in the percentage of BDNF-immunoreactive (IR) neuron profiles in the L5 DRG and marked elevation in the expression of BDNF-IR terminals in the spinal dorsal horn were observed following peripheral tissue inflammation produced by an intraplantar injection of Freund's adjuvant into the rat paws. These findings suggest that peripheral tissue inflammation induces an increased BDNF synthesis in the DRG and an elevated anterograde transport of BDNF to the spinal dorsal horn. The functional role of this increased BDNF was discussed briefly.

Animals↗
PubMed1997

Expression of mRNA for brain-derived neurotrophic factor in the dorsal root ganglion following peripheral inflammation.

It is well known that the nerve growth factor (NGF) may serve as a link between inflammation and hyperalgesia. Recent experiments showed that systemic injection of NGF dramatically stimulated the expression of brain-derived neurotrophic factor (BDNF) mRNA in the dorsal root ganglion (DRG). In the present study, we evaluated the change of BDNF mRNA in the DRG following peripheral inflammation and also observed colocalization of BDNF and trkA mRNAs by means of in situ hybridization histochemistry in rats. Peripheral tissue inflammation produced by an intraplantar injection of Freund's adjuvant into the paws significantly increased BDNF mRNA levels in the DRG and many neurons expressing trkA mRNA showed increased expession of BDNF mRNA. Intraplantar injection of antibody to NGF together with Freund's adjuvant prevented the increase in BDNF mRNA. These findings suggest that peripheral inflammation induces an increased expression of BDNF mRNA which is mediated by NGF in DRG.

Animals↗
PubMed1997

Caffeine- and inositol 1,4,5-trisphosphate-induced 45Ca2+ releases in the microsomes of tracheal epithelial cells.

Major parts of microsomes prepared from the epithelial cells of porcine trachea were tight-sealed vesicles since they showed a saturation of 45Ca2+ uptake and spontaneous releases of stored 45Ca2+ by the treatments of Ca2+-ionophore and Ca2+ channel agonists. In the presence of caffeine (10 mM), the maximal release of microsomal 45Ca2+ was observed at the extramicrosomal Ca2+ concentrations between 0.1 approximately 1 microM and at below or above this range of Ca2+ concentration the releases were decreased, forming a bell-shaped curve. These results indicate that the microsomal 45Ca2+ releases were mediated by ryanodine receptor, a caffeine-sensitive Ca2+ channel. Caffeine (10 mM) released 30.2 +/- 5.9% of microsomal 45Ca2+ while inositol 1,4,5-trisphosphate (InsP3, 10 microM) released 18.4 +/- 3.0% of the stored 45Ca2+. Caffeine-induced and InsP3-induced 45Ca2+ releases were additive, implying that these two types of 45Ca2+ releases are from physically distinct microsomes. Procaine, an antagonist of ryanodine receptor, selectively blocked the effect of caffeine but not the effect of InsP3. The results suggest that the epithelial cells of porcine trachea have caffeine-sensitive Ca2+ store in addition to InsP3-sensitive one.

Animals↗
PubMed1997

Typing of porcine reproductive and respiratory syndrome viruses by a multiplex PCR assay.

A rapid multiplex PCR assay was developed to distinguish between North American and European genotypes of porcine reproductive and respiratory syndrome (PRRS) virus after a portion of the polymerase gene (open reading frame 1b) was sequenced for two North American PRRS virus strains. DNA products with unique sizes characteristic of each genotype were obtained.

Animals↗
PubMed1997

Comparative study of serological methods for the detection of antibodies to porcine reproductive and respiratory syndrome virus.

A comparison was made of serological diagnostic methods used for the detection of antibodies against porcine reproductive and respiratory syndrome (PRRS) virus. In the "phase I" PRRS test panel comparison, a panel of sera collected from 135 pigs of various ages, from North American herds with and without PRRS histories, were sent to 4 different laboratories and tested by an indirect immunofluorescent assay (IFA), an immunoperoxidase monolayer assay (IPMA) and an indirect enzyme-linked immunosorbent assay (iELISA). In the "phase II" PRRS test panel comparison, a panel of 382 sera collected from pigs of various ages, PRRS histories, and from various locations in North America and France, were divided into 2 panels (A & B) and sent to 3 Canadian laboratories and tested by the IFA and iELISA. In the phase I comparison, agreement between the IFA of laboratory 4 and the iELISA and IPMA of laboratory 3 was excellent (kappa values of 95% and 98%, respectively). This contrasted with the poor agreement between these laboratories and the IFA results of laboratories 1 and 2 in the phase I trial. In the phase II comparison, the results demonstrated good agreement between various tests both within and between laboratories. The overall performance of the iELISA was superior in the combination of sensitivity (96.1%) and specificity (100%) relative to the reference classification of the serum samples and repeatability (kappa value 98%). The iELISA is technically superior to IFA and IPMA, time efficient, cost effective and suitable for testing of a large number of samples over a short period of time. Thus, the iELISA may be a better alternative to IFA or IPMA for routine detection of PRRS viral antibodies in swine sera.

Animals↗
PubMed1997

Performance of ELISA antigens prepared from 8 isolates of porcine reproductive and respiratory syndrome virus with homologous and heterologous antisera.

Porcine reproductive and respiratory syndrome virus (PRRSV) ELISA antigens of high quality were produced using 8 different isolates of PRRSV: the European Lelystad virus (LV), the U.S. MN-1b, 89-46448, 93-44927, and 93-24025B, and the Canadian LHVA-93-3, PA-8 and GH-6 virus isolates. The performance of each of these 8 antigens and a commercial PRRSV antibody test kit (Idexx's HerdChek) were measured against antisera raised in 5 groups of 6 piglets inoculated with either LV, MN-1b, 89-46448, 93-44927, or 93-24025B. Among the 8 isolates, the 89-46448 isolate produced the broadest spectrum of antigen and resulted in earlier detection of antibodies to various North American PRRSV isolates, followed by MN-1b as the 2nd best ELISA antigen for the detection of North American PRRSV antibodies. The GH-6 and PA-8 viral antigens exhibited restricted detection of PRRSV antibodies. The LV and 89-46448 combined antigens produced the best performance for the detection of antibodies against both European and North American antigenic types of PRRSV. Using 173 panel samples collected at 11 to 60 d after intranasal inoculation with 1 of the 5 PRRSV isolates, the sensitivities of the indirect ELISA used were 73.4%, 98.3%, 90.8%, 98.3%, 83.2%, 93.1%, 77.1%, 64.2%, 98.8% and 95.9% for LV, MN-1b, LHVA-93-3, 89-46448, 93-44927, 93-24025B, PA-8, GH-6 antigens, 89-46448-LV combined antigens and Idexx's PRRSV antibody test kit, respectively. All 8 antigens gave negative results with preinfection porcine sera (n = 30); high background or nonspecific reactions were not observed with the antigens.

Animals↗
PubMed1996

Expression of mRNAs for preprotachykinin and nerve growth factor receptors in the dorsal root-ganglion following peripheral inflammation.

Nerve growth factor (NGF) plays a dynamic role in the control of substance P (SP) levels and synthesis in the dorsal root ganglion (DRG). In the present study, in situ hybridization was used to examine the change of preprotachykinin (PTT), trkA and p75 mRNAs levels in the DRG after the injection of complete Freund's adjuvant into the hindpaws of rats. Peripheral tissue inflammation increased PTT and p75 mRNAs levels in the DRG, while trkA mRNA levels showed no change. These findings suggest that p75, in addition to trkA, also may be important in mediating the action of NGF on the synthesis of SP in the DRG following peripheral inflammation.

Animals↗
PubMed1996

Inhibition of noxious stimulus-evoked pain behaviors and neuronal fos-like immunoreactivity in the spinal cord of the rat by supraspinal morphine.

In previous studies, we reported that supraspinally administered DAMGO, a mu-opioid agonist, produces a dose-related, naloxone-reversible inhibition of formalin-evoked pain behaviors and spinal cord Fos-like immunoreactivity (FLI) in the rat spinal cord. Although these results support the hypothesis that activation of supraspinal mu-opioid receptors produces antinociception by increasing the activity of bulbospinal inhibitory pathways, other studies suggest that supraspinal morphine decreases rather than increases descending inhibitory control. In the present study, we specifically examined the effect of intracerebroventricular (i.c.v.) injection of morphine in the rat. Supraspinal morphine produced a dose-related, naloxone-reversible inhibition of both formalin-evoked behaviors nd spinal cord FLI. Although the magnitude of the antinociception produced by i.c.v. morphine in the formalin test was significantly correlated with the numbers of FLI neurons in the spinal cord, the lowest dose of i.c.v. morphine tested (0.70 nmol) produced a significant reduction of FLI in the superficial laminae without producing behavioral antinociception, which is consistent with our hypothesis that noxious stimulus-evoked Fos expression in the superficial laminae is a poor predictor of the magnitude of pain behavior. These data support the hypothesis that the antinociceptive effects of supraspinally administered morphine result from an increase in descending inhibitory control.

Analgesics↗
PubMed1996

An ELISA for porcine reproductive and respiratory syndrome: production of antigen of high quality.

A reliable method was developed to produce a viral antigen preparation from porcine reproductive and respiratory syndrome virus (PRRSV) infected MARC-145 cells by solubilizing the virus with Triton X-100. This method eliminated problems previously encountered with high background reactions associated with PRRSV antigen or cell control antigen. With this new antigen, an indirect enzyme-linked immunosorbent assay (ELISA) was adapted to detect swine serum anti-body against PRRSV. In the ELISA, non-specific reactions associated with test serum samples have been eliminated by utilizing an effective blocking serum diluent. The ELISA is more sensitive than an indirect immunofluorescent assay (IFA), particularly with late-infection sera, while maintaining a high diagnostic specificity. In a comparison of IFA and ELISA using sera collected from 250 pigs of various ages from 5 herds that had PRRS histories, IFA revealed 178 positive samples and 72 negative samples. All of the IFA-positive sera were proven to be ELISA reactors. However, nearly one-half (34/72) of the IFA-negative samples were also ELISA reactors. The diagnostic specificity and sensitivity of the ELISA were 100% and 96.6% with 257 serum samples collected from known healthy PRRS-negative swine herds and 57 sera collected from infected swine at 6 to 56 days after infection, respectively. The ELISA is technically superior to IFA, time-efficient and cost-effective, and suitable for testing of a large number of samples over a short period of time.

Animals↗
PubMed1995

Inducible nitric oxide synthase: identification of amino acid residues essential for dimerization and binding of tetrahydrobiopterin.

Nitric oxide synthases (NOSs) require tetrahydrobiopterin (BH4) for dimerization and NO production. Mutation analysis of mouse inducible NOS (iNOS; NOS2) identified Gly-450 and Ala-453 as critical for NO production, dimer formation, and BH4 binding. Substitutions at five neighboring positions were tolerated, and normal binding of heme, calmodulin, and NADPH militated against major distortions affecting the NH2-terminal portion, midzone, or COOH terminus of the inactive mutants. Direct involvement of residues 450 and 453 in the binding of BH4 is supported by the striking homology of residues 448-480 to a region extensively shared by the three BH4-utilizing aromatic amino acid hydroxylases and is consistent with the conservation of these residues among all 10 reported NOS sequences, including mammalian NOSs 1, 2, and 3, as well as avian and insect NOSs. Altered binding of BH4 and/or L-arginine may explain how the addition of a single methyl group to the side chain of residue 450 or the addition of three methylenes to residue 453 can each abolish an enzymatic activity that reflects the concerted function of 1143 other residues.

Amino Acid Sequence↗
PubMed1995

Chronic arthritis increases tyrosine hydroxylase mRNA levels in the pontine noradrenergic cell groups.

In situ hybridization was used to examine the change of tyrosine hydroxylase(TH) mRNA levels in the pontine noradrenergic cell groups of chronic monoarthritic rats induced by adjuvant inoculation. The number of TH mRNA-expressing neurons and grains per labeled neuron in the A5,A6 and A7 cell groups on the ipsilateral and contralateral sides significantly increased 2 weeks after adjuvant inoculation into the left tibio-tarsal joint, compared to controls. These results suggest that noradrenalin in the pontine region may play a role in modulating chronic nociceptive stimuli.

Adrenergic Fibers↗
PubMed1995

Nitric oxide suppression of human hematopoiesis in vitro. Contribution to inhibitory action of interferon-gamma and tumor necrosis factor-alpha.

IFN-gamma and TNF-alpha, potent inhibitors of hematopoiesis, induce nitric oxide synthase (NOS) in various cell types. When normal human bone marrow (BM) or CD34+ cells were exposed to NO, inhibition of colony formation was dose dependent and direct. NO induced apoptosis in BM progenitors, as shown by electrophoretic detection of DNA degradation and deoxynucleotidyl transferase assay. Using PCR and immunoprecipitation, we found inducible NOS (iNOS) mRNA and iNOS protein in BM after stimulation with IFN-gamma or TNF-alpha. iNOS mRNA was also detected by PCR in highly purified CD34+ cells; TNF-alpha or IFN-gamma increased iNOS expression. The presence of iNOS in CD34+ cells was confirmed in single cells by immunochemical staining. NG-Monomethyl-L-arginine (MM-Arg), an NOS inhibitor, partially reversed the effects of TNF-alpha and, to a lesser extent, IFN-gamma in methylcellulose culture of total BM and CD34+ cells, and inhibited apoptosis of BM cells induced by these cytokines. When the effects of competitive iNOS inhibition were tested on more immature progenitors, MM-Arg increased the number of long-term BM culture-initiating cells in control cultures but failed to protect these cells from the inhibitory action of IFN-gamma and TNF-alpha. Our results suggest that NO may be one mediator of cytokine-induced hematopoietic suppression.

Amino Acid Oxidoreductases↗
PubMed1994

Splenic lymphoid change in abdominal neoplasmic patients--analysis of 121 cases.

Because the spleen is likely to play a specific role in immunity, we have tried to observe the influence of the abdominal neoplasms on splenic lymphoid tissue as well as the distribution and localization of immunoregulatory cells with a special attention to the marginal zone, using splenectomy specimens in the various kinds of 121 abdominal neoplasm patients. As a control group, twenty-six splenectomy specimens from patients with traumatic rupture were used. In splenic size and weight, there was a statistically meaningful increase in the patients with abdominal neoplasms. Among those patients, the evolving activated immune reaction (EVA) was 60.2%, the early activated immune-reaction (EAA) 39.0%, the mixed evolving activated and granulomatous reaction (MIX) 0.8%, unlike EVA 30.8%, EAA 69.2%, and MIX 0% in the normal control group. The reason for this change may be explained by activated lymphoid tissue in the form of EVA type. In conclusion, the splenic lymphoid tissue in the various kinds of abdominal neoplasms, mostly malignant, revealed the chronic immune activated state characterized by the increased number of prominent germinal centers and distinct marginal zones, the latter of which revealed the positive reaction for L26, IgM and IgG, and negative for IgD, as well as showing increased natural killer and dentritic reticulum cells identified by Leu7 and S-100 protein respectively. Therefore, we could at least find the significance of the immunologic role of the spleen in the case of abdominal neoplasms, mostly from malignancy.

Abdominal Neoplasms↗
PubMed1994

Interphase cytogenetics of lung tumors using in situ hybridization: numerical aberrations.

OBJECTIVES: Since conventional cytogenetic analysis for bronchogenic carcinogenesis is limited by the difficulty to get enough number of high quality metaphase spreads, the development of new method to overcome above problems is strongly needed. Therefore, the introduction of non-radioactive in situ hybridization (ISH) with pericentromeric chromosome probes gave us the way to investigate the genetic events during carcinogenic process. We applied this method on lung cancer tissue to validate the possibility of this method for general usage and to analyze numerical chromosome aberration status and their clinical correlations. METHODS: A set of satellite DNA probes specific for chromosome 3, 7, 9, 11, and 17 was hybridized directly to paraffin-embedded tissue section of 30 non-small cell lung cancers. Mean chromosome index of each chromosome and frequency of polysomy for each chromosome were calculated. RESULTS: Mean chromosome indices for chromosome 3, 7, 9, 11, and 17 were 1.10, 1.13, 1.17, 1.12, and 1.17, respectively. Polysomy for a set of chromosomes was detected in all 30 cases except 4 cases which showed hypoploidy only for chromosome 3 or 7 in 2 cases and diploidy only for chromosome 3 or 11 in 2 cases. Among the set of chromosomes, mean chromosome index and polysomy frequency for chromosome 9 & 17 were significantly higher than that for others. Mean chromosome index or polysomy pattern for each chromosome was not much different among cell types or clinical stages. CONCLUSIONS: Our results show that chromosome ISH can be used to screen for numerical chromosome aberrations on paraffin tissue sections and further studies for ISH analysis with different probes on same tumor area or double-target ISH in large scale are needed to confirm above results and to elucidate the specific meanings.

Carcinoma, Non-Small-Cell Lung↗