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Biomedical subjects

J H Sohn

Publications and source records attributed to J H Sohn.

At least 19 recordsLinked to original sources
PubMed2006

Association of obesity, serum glucose and lipids with the risk of advanced colorectal adenoma and cancer: a case-control study in Korea.

BACKGROUND: Previous studies on colorectal cancer risk suggest that obesity, serum lipids and glucose might be related to colorectal carcinogenesis. This case-control study was conducted to investigate the association between obesity, serum lipids and glucose, and the risk of advanced colorectal adenoma and cancer. METHODS: Patients with histologically confirmed colorectal cancers (n=105), same number of patients with advanced colorectal adenomas matched by age and sex, and the same number of controls matched by age and sex were selected in Hanyang University Guri Hospital between January 2002 and June 2004. RESULTS: Adenoma and cancer group showed significantly higher levels of mean body mass index and serum glucose. Cancer group also showed significantly lower mean serum lipids levels than controls. We used an unordered polytomous logistic model to calculate multivariate odds ratios for advanced adenoma and cancer relative to controls. Higher serum glucose level was more strongly associated with increased risk of cancer relative to controls (odds ratio, 3.0; 95% confidence interval, 0.9-9.8) than with increased risk of advanced adenoma (odds ratio, 2.1; 95% confidence interval, 0.9-5.4). Higher body mass index was strongly associated with increased risk of advanced adenoma (odds ratio, 10.8; 95% confidence interval, 4.6-25.3), but associated with attenuated risk of cancer (odds ratio, 2.3; 95% confidence interval, 0.9-5.8). Serum triglycerides and cholesterol levels were strongly associated with reduced risk of cancer (odds ratio, 0.3; 95% confidence interval, 0.1-0.8 and odds ratio, 0.2; 95% confidence interval, 0.1-0.6, respectively). CONCLUSIONS: Obesity and hyperglycaemia are positively related to advanced colorectal adenoma formation. Furthermore, hyperglycaemia plays an important role in progression to cancer. Findings on an inverse relationship between serum triglyceride and cholesterol levels and the risk of colorectal cancer may be the secondary results from metabolic or nutritional changes in advanced colorectal cancer patients and should be clarified in further studies.

Adenomatous Polyps↗
PubMed2005

Huge gastric diospyrobezoars successfully treated by oral intake and endoscopic injection of Coca-Cola.

A diospyrobezoar is a type of phytobezoar that is considered to be harder than any other types of phytobezoars. Here, we describe a new treatment modality, which effectively and easily disrupted huge gastric diospyrobezoars. A 41-year-old man with a history of diabetes mellitus was admitted with lower abdominal pain and vomiting. Upper gastrointestinal endoscopy revealed three huge, round diospyrobezoars in the stomach. He was made to drink two cans of Coca-Cola every 6 h. At endoscopy the next day, the bezoars were partially dissolved and turned to be softened. We performed direct endoscopic injection of Coca-Cola into each bezoar. At repeated endoscopy the next day, the bezoars were completely dissolved.

Administration, Oral↗
PubMed2005

Phase II study of concurrent chemoradiotherapy with capecitabine and cisplatin in patients with locally advanced squamous cell carcinoma of the head and neck.

We aimed to evaluate the efficacy and safety of concurrent chemoradiotherapy with capecitabine and cisplatin in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN). In total, 37 patients with stage III or IV SCCHN were enrolled on the study. The chemotherapy consisted of two cycles of intravenous cisplatin of 80 mg m(-2) on day 1 and oral capecitabine 825 mg m(-2) twice daily from day 1 to day 14 at 3-week intervals. The radiotherapy (1.8-2.0 Gy 1 fraction day(-1) to a total dose of 70-70.2 Gy) was delivered to the primary tumour site and neck. The primary tumour sites were as follows: oral cavity (n=6), oropharynx (n=11), hypopharynx (n=8), larynx (n=3), nasopharynx (n=6), and paranasal sinus (n=3). After the chemoradiotherapy, 29 complete responses (78.4%) and 6 partial responses (16.2%) were confirmed. Grade 3 or 4 neutropenia occurred only in two patients, plus grade 3 febrile neutropenia was observed only in one patient. At a median follow-up duration of 19.8 months, the estimated overall survival and progression-free survival rate at 2-year was 76.8 and 57.9%, respectively. Concurrent chemoradiotherapy with capecitabine and cisplatin was found to be well tolerated and effective in patients with locally advanced SCCHN.

Adult↗
PubMed2004

Evaluation of a novel wind tunnel for the measurement of the kinetics of odour emissions from piggery effluent.

A novel laboratory wind tunnel, with the capability to control factors such as air flow-rate, was developed to measure the kinetics of odour emissions from liquid effluent. The tunnel allows the emission of odours and other volatiles under an atmospheric transport system similar to ambient conditions. Sensors for wind speed, temperature and humidity were installed and calibrated. To calibrate the wind tunnel, trials were performed to determine the gas recovery efficiency under different air flow-rates (ranging from 0.001 to 0.028m3/s) and gas supply rates (ranging from 2.5 to 10.0 L/min) using a standard CO gas mixture. The results have shown gas recovery efficiencies ranging from 61.7 to 106.8%, while the average result from the trials was 81.14%. From statistical analysis, it was observed that the highest, most reliable gas recovery efficiency of the tunnel was 88.9%. The values of air flow-rate and gas supply rate corresponding to the highest gas recovery efficiency were 0.028 m3/s and 10.0 L/min respectively. This study suggested that the wind tunnel would provide precise estimates of odour emission rate. However, the wind tunnel needs to be calibrated to compensate for errors caused by different air flow-rates.

Air Pollutants↗
PubMed2003

Association of maspin expression with the high histological grade and lymphocyte-rich stroma in early-stage breast cancer.

AIMS: Maspin is a recently described member of the serpin family or protease inhibitors that is known to be a tumour suppressor gene product. Loss of maspin expression has been found in most breast cancer cases and is correlated with cell motility and tumour invasiveness. However, its precise role in human breast cancer remains to be discovered. We aimed to evaluate the role of maspin in early-stage breast cancer. METHODS AND RESULTS: We analysed the expression of maspin in 192 stage I and II primary breast cancers by immunohistochemistry. Of these cases, 34.4% showed maspin expression. Maspin expression was more frequently found in invasive ductal carcinoma (36.4%) than in invasive lobular carcinoma (7.1%). High maspin expression was demonstrated in breast cancers showing high histological grade or lymphocyte-rich stroma (P < 0.05). Maspin expression was not associated with overall and disease-free survival rate of breast cancer. CONCLUSIONS: The results indicate that different biological mechanisms may be responsible for maspin expression in histologically distinct types of breast cancer. Our survey suggests that maspin expression in breast cancer might have a compensatory role rather than prognostic one.

Adenocarcinoma↗
PubMed2001

Cloning and characterization of the Hansenula polymorpha homologue of the Saccharomyces cerevisiae MNN9 gene.

A gene homologous to Saccharomyces cerevisiae MNN9 has been cloned and characterized in the methylotrophic yeast Hansenula polymorpha. This gene was cloned from a H. polymorpha genomic DNA library using the S. cerevisiae MNN9 gene as a probe. The H. polymorpha MNN9 homologue (HpMNN9) contained a 1062 bp open reading frame encoding a predicted protein of 354 amino acids. The deduced amino acid sequence showed 58% and 51% identity, respectively, with the S. cerevisiae and Candida albicans Mnn9 proteins. Disruption of HpMNN9 leads to phenotypic effects suggestive of cell wall defects, including detergent sensitivity and hygromycin B sensitivity. The hygromycin B sensitivity of S. cerevisiae mnn9 null mutant was complemented in the presence of the HpMNN9 gene. The DNA sequence of the H. polymorpha homologue has been submitted to GenBank with the Accession No. AF264786.

Amino Acid Sequence↗
PubMed2001

Development of expression systems for the production of recombinant human serum albumin using the MOX promoter in Hansenula polymorpha DL-1.

To optimize the secretory expression of recombinant human serum albumin (HSA) under the control of methanol oxidase (MOX) promoter in the methylotrophic yeast Hansenula polymorpha DL-1, we analyzed several parameters affecting the expression of HSA from the MOX promoter. Removal of the 5'-untranslated region derived from HSA cDNA in the expression cassette led to at least a fivefold improvement of HSA expression efficiency at the translational level. With the optimized expression cassette, the gene dosage effect on HSA expression was abolished and thus, a single copy of the expression vector integrated into the MOX locus became sufficient for the maximal expression of HSA. Northern blot analysis revealed that the levels of HSA transcript did not increase any further upon increasing copy number. The mox-disrupted (mox Delta) transformant was constructed, in which the genomic MOX gene was transplaced with the HSA expression cassette, to examine the effect of the methanol oxidase-deficient phenotype of the host on HSA expression. The mox Delta transformant showed higher levels of HSA production in shake-flask cultures than the MOX wild-type transformant, especially at low concentrations of methanol and a twofold higher specific HSA production rate in fed-batch fermentation with an abrupt induction mode. The native prepro signal sequence of HSA secreted in H. polymorpha was correctly processed and the mature recombinant protein had a pI value identical to that of the authentic HSA. Our results suggest that the H. polymorpha expression systems developed in this study are suitable for large-scale production of recombinant albumin.

5' Untranslated Regions↗
PubMed2001

Current status of the anticoagulant hirudin: its biotechnological production and clinical practice.

Hirudin is a potent thrombin inhibitor originally derived from the medicinal leech, Hirudo medicinalis. Owing to its high affinity and specificity for thrombin, hirudin has been intensively investigated for research and therapeutic purposes. The investigation of hirudin has contributed greatly to the understanding of the mode of action of thrombin and the clotting system. Hirudin and several hirudin analogues have also been demonstrated to have several advantages as a highly specific anticoagulant over the most widely used drug, heparin. Due to the great demand for hirudin in physicochemical and clinical studies, various recombinant systems have been developed, using bacteria, yeasts, and higher eukaryotes, to obtain the biologically active hirudin in significant quantities. After 10 years of clinical applications, two recombinant hirudins and a hirudin analogue have gained marketing approval from the United States Food and Drug Administration, for several applications. Clinical trials are currently ongoing for other treatments for thrombotic disease. As a consequence, it is conceivable that hirudin may expand its therapeutic utility over heparin in the near future.

Amino Acid Sequence↗
PubMed2001

Molecular characterization of the actin-encoding gene and the use of its promoter for a dominant selection system in the methylotrophic yeast Hansenula polymorpha.

The actin gene (ACT) from the methylotrophic yeast Hansenula polymorpha was cloned and its structural feature was characterized. In contrast to the actin genes of other ascomycetous yeasts, which have only one large intron, the H. polymorpha ACT gene was found to be split by two introns. The H. polymorpha ACT introns were correctly processed in the heterologous host Saccharomyces cerevisiae despite appreciable differences in the splice site sequences. The promoter region of H. polymorpha ACT displayed two CCAAT motifs and two TATA-like sequences in a configuration similar to that observed in the S. cerevisiae actin promoter. A set of deleted H. polymorpha ACT promoters was exploited to direct expression of the bacterial hygromycin B resistance (hph) gene as a dominant selectable marker in the transformation of H. polymorpha. The resistance level of H. polymorpha transformants to the antibiotic was shown to be dependent on the integration copy number of the hph cassette. The selectivity of the hygromycin B resistance marker for transformants of higher copy number was remarkably increased with the deletion of the upstream TATA-like sequence, but not with the removal of either CCAAT motif, from the H. polymorpha promoter. The dosage-dependent selection system developed in this study should be useful for genetic manipulation of H. polymorpha as an industrial strain to produce recombinant proteins.

Actins↗
PubMed2001

Electrodermal and cardiovascular manifestations of emotions in children.

The purpose of this paper is to analyze the current state of developmental researches in the area of psychophysiology of emotions in preschool and elementary school children. Electrodermal and cardiovascular activity measures are considered as the sources of indices of the autonomic nervous system activation during emotion-eliciting stimulation in children. We discuss the question of sensitivity of phasic and tonic autonomic measures for the identification of occurrence of emotion, mapping it along with valence and arousal dimensions in affective space, and to further differentiate emotions by their physiological manifestations. Considered are the conceptual and methodological issues related to psychophysiological measurements and developmental factors affecting the emotional reactivity in children. Special attention is devoted to the developmental aspects of psychophysiological studies on emotion such as the maturation of organs, integration of the autonomic and central nervous systems, age and gender-related changes in autonomic reactivity, and development of inhibitory control. Summarized are main findings relevant to psychophysiology of emotions in preschool and early school-age children and suggested are most perspective directions of their integration in the framework of modern theories of emotion.

Cardiovascular Physiological Phenomena↗
PubMed2001

Squamous cell carcinoma of the cornea.

In this paper, a case of corneal squamous cell carcinoma is reported. Invasive squamous cell carcinoma of the cornea is a rare disorder and has not been previously described in the Korean literature. In this case, the invasive squamous cell carcinoma of the cornea was treated by complete excision and cryotherapy. No evidence of metastasis or recurrence has been found since the procedure. Complete excision and adjunctive cryotherapy has become the treatment of choice because of the higher recurrence rate following a simple excision.

Aged↗
PubMed2001

Depletion of intracellular zinc and copper with TPEN results in apoptosis of cultured human retinal pigment epithelial cells.

PURPOSE: Although zinc deficiency may contribute to the pathogenesis of age-related macular degeneration, how it leads to retinal pigment epithelium (RPE) degeneration is unknown. To investigate this, cultured human RPE cells were rendered zinc depleted with a membrane-permeant metal chelator, N,N,N',N-tetrakis(2-pyridylmethyl) ethylenediamine (TPEN), and the resultant cytopathic changes were examined. METHODS: RPE cell degeneration was examined with light microscopy, TdT-mediated dUTP nick end labeling (TUNEL) staining, Hoechst dye staining, and electron microscopy and quantified with cell counting or lactate dehydrogenase release assay. The effect of sublethal zinc depletion on the vulnerability of RPE cells to UV irradiation or hydrogen peroxide (H(2)O(2)) exposure, was studied in cultures without or with pretreatment with low-concentration TPEN. RESULTS: Exposure to 1 to 4 microM TPEN for 48 hours induced RPE cell death in a concentration-dependent manner. Features of apoptosis such as membrane blebbing, chromatin condensation, nuclear fragmentation, and caspase-3 activation, accompanied the TPEN-induced cell death. Addition of equimolar zinc or copper completely reversed TPEN-induced apoptosis, whereas addition of iron had no effect. As in apoptosis of several other cell types including neurons, a protein synthesis inhibitor as well as caspase inhibitors blocked TPEN-induced apoptosis. On the contrary, at sublethal concentrations, TPEN increased the vulnerability of RPE cells to subsequent UV irradiation but not to H(2)O(2) exposure. CONCLUSIONS: The present results suggest that depletion of intracellular zinc and copper, but not copper alone, may be harmful to RPE cells, directly inducing apoptosis or indirectly increasing vulnerability of RPE cells to UV injury. The present culture model may be useful for gaining insights into the mechanisms of zinc depletion-associated RPE cell degeneration.

Apoptosis↗
PubMed2001

Requirement of B7-mediated costimulation in the induction of experimental autoimmune anterior uveitis.

PURPOSE: To study the role of costimulatory signaling through the CD28-B7 interaction in experimental autoimmune anterior uveitis (EAAU). METHODS: Naive Lewis rats were immunized with insoluble melanin-associated antigen (MAA) derived from bovine iris and ciliary body. CTLA4-Fc, a recombinant protein comprised of the extracellular domain of human CTLA4 bound to mouse IgG2a Fc, was used to block the CD28-B7 interaction. A mutant version (CTLA4-Fc-mutant) was used as a control. The effect of CTLA4-Fc on the in vivo induction of disease with MAA was studied. Subsequently, the mechanism by which CTLA4-Fc blocked the interaction of CD28 and B7 was investigated in vivo, using the adoptive transfer of T cells derived from CTLA4-Fc-treated rats, and in vitro, using the proliferative response and cytokine production of MAA-T cells in the presence of CTLA4-Fc. RESULTS: CTLA4-Fc markedly reduced the incidence and severity of EAAU in Lewis rats after sensitization with MAA. The adoptive transfer of sensitized T cells from CTLA4-Fc-treated donors did not induce EAAU in naive recipients. CTLA4-Fc inhibited the expansion of antigen-specific MAA-T cells and the production of TNF-alpha. CONCLUSIONS: The costimulatory signal delivered through CD28-B7 is required for the induction and pathogenesis of EAAU. In the absence of this signal, antigen-specific expansion of MAA reactive T cells as well as production of TNF-alpha is inhibited. Abrogation of this costimulatory signal may be an important therapeutic option for EAAU.

Abatacept↗
PubMed2000

Antiallodynic effects produced by stimulation of the periaqueductal gray matter in a rat model of neuropathic pain.

It has been well documented that there is opioid resistance in neuropathic pain. This indicates that the endogenous opioid system may not be involved effectively in modulating neuropathic pain. The present study sought to determine if activation of the descending pain inhibition system might produce analgesia in the animal neuropathic model we developed. Under ketamine anesthesia, male Sprague-Dawley rats were chronically implanted with stimulating electrodes in the ventral periaqueductal gray matter (PAG) and both the tibial and sural nerves of the sciatic nerve branches were severed. Pain sensitivity was measured with a von Frey filament and acetone applied to the sensitive area for 1 week postoperatively. Rats with neuropathic pain syndrome after transection of the tibial and sural nerves were tested as to the analgesic effects of ventral PAG stimulation for an additional two weeks. Electrical stimulation of the ventral PAG turned out to be highly effective in alleviating neuropathic pain. Mechanical allodynia and cold allodynia were reduced by PAG stimulation. Naloxone reversed the antiallodynic effects of ventral PAG stimulation. These results suggest that activation of the descending pain inhibition system including the ventral PAG reduces neuropathic pain syndrome and that opiates are involved in this system.

Analgesia↗
PubMed2000

Microinjection of opiates into the periaqueductal gray matter attenuates neuropathic pain symptoms in rats.

We have previously demonstrated that electrical stimulation of the ventral periaqueductal gray matter (PAG) produced analgesia in neuropathic pain in rats. Opioids were also shown to be involved in analgesic effects. This study sought to determine whether opiates microinjected into the ventral PAG produce analgesia. Male Sprague-Dawley rats were chronically implanted with a guide cannula in the PAG under pentobarbital anesthesia and both the tibial and sural nerves were completely cut. Pain sensitivity was postoperatively measured with a von Frey filament and acetone applied to the sensitive area for 1 week. Opioids such as [D-Ala2,N-MePhe4,Gly(ol)5]-enkephalin (DAMGO) and [D-Pen ,D-Pen5]-enkephalin (DPDPE) were injected into the PAG. DAMGO, a mu-opioid agonist, and DPDPE, a delta-opioid agonist, were highly effective in reducing neuropathic pain. These effects were reversed by naloxone. These results suggest that the neurons in the ventral PAG are activated by opioids to produce analgesia and that specific opioid receptors are involved in the descending pain inhibition system from the PAG.

Analgesics, Opioid↗
PubMed2000

The new genotypic human calicivirus isolated in Seoul.

A new type of human calicivirus (HuCV) showing the classic cup-shaped surface morphology was identified in the stool sample from a child with symptoms of acute gastroenteritis in Seoul, Korea (SK virus). Genomic RNA was extracted directly from the stool sample, and the nucleotide sequence of 3.2 kb of the 3' end of SK virus was determined from cDNA. This region spanned sequences from the RNA-dependent RNA polymerase (RDRP) region in the open reading frame 1 (ORF1) to the 3' poly A tail. The non-structural and capsid protein coding sequences were fused in a single ORF as observed in Manchester type (Genogroup III). However, ORF2 of Manchester virus was missing in SK virus. In RDRP region, SK virus showed amino acid and nucleotide identities of 74-75% and 68-69% respectively, with those of Manchester virus, while showed 34-46% and 55-60% identities respectively with those of other human caliciviruses. However, capsid protein of SK virus showed a partial (29-46%) amino acid identity with those of other caliciviruses including Manchester type. The closest resemblance in amino acid (97-99%) and nucleotide sequence (85-86%) identities were found in RDRP region with Vanderbijlpark and Pretoria isolates recently found in South Africa. These results suggest that SK virus together with Vanderbijlpark and Pretoria isolates belong to a new type different from Manchester virus.

Amino Acid Sequence↗