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Biomedical subjects

J H Jeon

Publications and source records attributed to J H Jeon.

14 recordsLinked to original sources
PubMed2006

Cloning, expression, and characterization of a methionyl aminopeptidase from a hyperthermophilic archaeon Thermococcus sp. NA1.

Genomic analysis of a hyperthermophilic archaeon Thermococcus sp. NA1 revealed the presence of an 885-bp open reading frame encoding a protein of 295 amino acids with a calculated molecular mass of 32,981 Da. Analysis of the deduced amino acid sequence showed that amino acid residues important for catalytic activity and the metal binding ligands conserved in all of methionyl aminopeptidases (MetAP) were also conserved and belonged to type IIa MetAP. The protein, designated TNA1_MetAP (Thermococcus sp. NA1 MetAP), was cloned and expressed in Escherichia coli. The recombinant enzyme was a Mn(2+)-, Ni(2+)-, Fe(2+)-, or Co(2+)-dependent metallopeptidase. Optimal MetAP activity against L: -methionine p-nitroanilide (Met-pNA) (K (m) = 0.68 mM) occurred at pH 7.0 and 80 to 90 degrees C. The MetAP was very unstable compared to Pyrococcus furiosus MetAP, which was completely inactivated by heating at 80 degrees C for 5 min. It seemed likely that the cysteine residue (Cys53) played a critical role in regulating the thermostability of TNA1_MetAP.

Amino Acid Sequence↗
PubMed2006

Evaluation of BASINS/WinHSPF applicability for pollutant loading estimation for a Korean watershed.

Applicability of a widely accepted watershed-based water quality assessment tool (BASINS) and its associated watershed model (WinHSPF) was evaluated on the Seamangeum watershed in Korea. The study site is the largest polder project area in Korea and its environmental quality has been debated for the last five years. BASINS was found to be a convenient and powerful tool for assessment of watershed characteristics, and provided various tools to delineate the watershed into land segments and river reaches, reclassify land use, and parameterize for WinHSPF simulation. Calibration results were satisfactory showing model efficiency over 0.80 for stream flow, temperature, and dissolved oxygen simulation, and model output for water quality constituents also reasonably matched the observed data. It was demonstrated that calibration with dry-day data for a relatively long period might be adequate to simulate hydrologic characteristics and water quality of the watershed with WinHSPF, and using parameters generated with BASINS for nonpoint source pollution simulation is suggested when enough wet-day monitoring data are not available. The unit-area load of biochemical oxygen demand, total nitrogen, and total phosphorus was 27.8, 48.2, and 4.3 kg/ha/yr, respectively. These values are within the expected range but on the high side of the reported values, which implies that effective control measures are required to protect water quality of the downstream reservoir. Overall, BASINS/WinHSPF was applicable and found to be a powerful tool in pollutant loading estimation from the watershed, and its use in Korea is recommended.

Calibration↗
PubMed2006

Water quality modeling to evaluate BMPs in rice paddies.

A water quality model applicable to rice paddies was developed using field data from 1999-2002. Use of the Dirac delta function efficiently explained the nutrient-concentration characteristics of ponded water. The model results agreed reasonably well with the observed data. The ponded-water quality was influenced primarily by fertilization; nutrient concentration was especially high during early cultivation periods. Reducing surface drainage during the fertilization period may substantially reduce nonpoint source loading from paddies. Increased weir heights and shallow irrigation methods were evaluated by the model as practical methods for reducing nutrient loading from paddies. These methods were effective in reducing surface drainage and are suggested as "best management practices" (BMPs) if applied based on site-specific paddy conditions.

Agriculture↗
PubMed2005

Use of a crush-reducing device to decrease crushing of suckling piglets by sows.

Weanling pigs tend to avoid wind, and suckling piglets are thought to be more sensitive to wind than weanlings, owing to their thinner s.c. fat layer. We developed a crush-reducing device based on the anticipated behavior of suckling piglets toward wind and evaluated the performance of the device through field testing. The crush-reducing device consisted of six photo sensors, a controller, six solenoid valves, and an air compressor. In this study, 206 sows and their suckling piglets (Landrace xYorkshire) were investigated to ascertain the individual effects of several factors. Some of the newborn piglets were cross-fostered before the crush-reducing device was implemented. Litter weights were measured on d 0 and 4 to determine the influence of the crush-reducing device on the weights of suckling piglets. The crushing of suckling piglets by sows was affected by season (P < 0.01) and litter size (P < 0.05), but not by the parity of the sows; however, the number of crushed piglets per litter was less (P < 0.01) in the crush-reducing device group (0.05 +/- 0.02 crushed piglets/litter) than in the control group (0.23 +/- 0.04 crushed piglets/litter), regardless of litter size or season. The BW gain of suckling piglets did not differ between the control and the crush-reducing device groups. Based on these results, the crush-reducing device is expected to decrease the number of crushed piglets per litter without influencing the BW gain of suckling piglets, thereby greatly contributing to the productivity of pig breeders.

Animal Husbandry↗
PubMed2005

Mass balance analysis and water quality model development for loading estimates from paddy fields.

Mass balance analysis and water quality model development for paddy field were performed using field experimental data during 2001-2002. About half (47-62%) of the total outflow was lost by surface drainage, with the remainder (490-530 mm) occurring by evapotranspiration. Most of nutrient inflow and outflow were mediated by fertilization and plant uptake, respectively. Nutrient outflow by surface drainage runoff was substantial about 15%-29% for T-N and 6%-13% for T-P. However, the responses of yield and drainage outflow to fertilization were not significant in this study. A water quality model applicable to paddy fields was developed and it demonstrates good agreement with observed data. The nutrient concentration of ponded water was high by fertilization at early culture periods, so reducing surface drainage during fertilization period can reduce nutrient loading from paddy fields. Shallow irrigation, raising the weir height in diked rice fields, and minimizing forced surface drainage are suggested to reduce surface drainage outflow.

Fertilizers↗
PubMed2004

Expression of the hepatitis B surface S and preS2 antigens in tubers of Solanum tuberosum.

In an attempt to develop an edible vaccine, we transformed a recombinant hepatitis B virus (HBV) gene encoding the middle protein of HBV that contains the surface S and preS2 antigen into potato by Agrobacterium-mediated transformation. The HBV gene was under control of either the CaMV 35S promoter, the double 35S promoter with the AlMV 5' non-translated leader sequence, or the tuber-specific patatin promoter. HBV mRNA levels were higher with the 35S promoter than with the double 35S and patatin promoters; however, the levels of the S and preS2 antigen in the transformed tubers were higher with the patatin promoter than with the CaMV 35S and double promoters. The levels of preS2 antigen produced are the highest reported to date. Transgenic potato tubers were fed to mice, and the mice showed an immune response against the HBV S antigen.

Animal Feed↗
PubMed2001

Implication of co-measured platelet factor 4 in the reliability of the results of the plasma transforming growth factor-beta 1 measurement.

We examined the possible alteration of circulating transforming growth factor-beta1 (TGF-beta1) concentrations in a time-dependent fashion in human plasma. Plasma TGF-beta1 was measured three times at 2 week-intervals from each of 12 healthy participants. Platelet factor 4 (PF4) was measured in parallel with TGF-beta1 to estimate the degree of platelet degranulation. TGF-beta1 levels of the second and third plasma samples, in which PF4s were measured as < approximately 1000 IU/ml, were relatively low and fell in a narrow range. However, TGF-beta1 levels of the first samples, in most of which PF4s were > approximately 1000 IU/ml, appeared much higher and more variable than those of the second or third samples. These results indicate that the platelet degranulation accounted for the higher TGF-beta1 levels in the first samples, and thus did not support our initial assumption. We, nevertheless, could propose a useful guidance in the assessment of TGF-beta1 levels in plasma. When the PF4 level is measured as < approximately 1000 IU/ml under our assay conditions, the TGF-beta1 level in a given plasma sample might be accepted as a reliable value considering the effect of platelet degranulation on TGF-beta1 level.

Adult↗
PubMed1998

Platelet adhesion on the gradient surfaces grafted with phospholipid polymer.

We have synthesized omega-methacryloyloxyalkyl phosphorylcholine (MAPC) polymers as new blood-compatible materials, with attention to the surface structure of the biomembrane and investigated their blood compatibility. The blood compatibility observed on the MAPC polymers is due to their strong affinity to phospholipids. When the blood comes in contact with the MAPC polymer, phospholipids in the plasma preferentially adsorb on the surface, compared with the plasma proteins or cells. The adsorbed phospholipids construct a biomembrane-like structure on the MAPC polymer surface. The MAPC polymers then have an excellent blood compatibility. In this study, we prepared a gradient poly(MAPC)-grafted polyethylene (PE) surface using a corona discharge treatment method to clarify the effect of the chemical structure of the MAPC unit on the blood compatibility of the MAPC polymers. The surface composition of MAPC and the hydrophilicity on the poly(MAPC)-grafted PE surface were determined by X-ray photoelectron spectroscopic (XPS) analysis and contact angle measurement with water, respectively. The phosphorus/carbon (P/C) ratio determined by the XPS analysis increased, but the water contact angle decreased with increasing corona irradiation energy. These results indicated that the surface density of the MAPC unit was increased. More than 2.5 cm from the starting point of the corona irradiation, the P/C ratio and water contact angle of the surface achieved a constant level. Thus, the surface was completely covered with the grafted poly(MAPC) chain. The effect of the methylene chain length of the MAPC unit on surface properties was also observed. The phospholipid polar group of the MAPC unit was effectively exposed on the surface as the chain length became longer. Moreover, the hydrophobicity of the surface was increased with the increase in the methylene chain length of the MAPC unit. The number of platelets adhering to the poly(MAPC)-grafted PE surface was reduced from the same point where the P/C ratio became constant.

Animals↗
PubMed1998

Eosinophil-induced chronic hepatitis.

Chronic hepatitis associated with hypereosinophilia has been very rarely reported worldwide. A 7-month-old male infant presented with a high fever, cough, non-projectile vomiting and hepatomegaly. The eosinophil count of the peripheral blood increased up to 21,500/mm3 (49% of WBC). The infant had a history of frequent contact with a neighbor keeping a pigsty. The pathologic examinations of the liver showed severe porto-periportal necroinflammation with marked eosinophilic infiltration, giant cell transformation and ballooning degeneration of hepatocytes, and degranulation of the eosinophils. Bone marrow showed increased eosinophils and decreased myeloid series. Pericardial effusion and bilateral pulmonary consolidation were noted. Corticosteroid aggravated the clinical symptoms of the infant. Anthelmintic treatment significantly normalized the eosinophil count and liver function tests, but cardiopulmonary manifestations continued.

Eosinophils↗
PubMed1998

Platelet and cell interactions on gold sputter-deposited polymeric surfaces.

Surface treatment as gold sputter-deposited treatment onto various polymeric surfaces has been investigated to improve the cell-, tissue- and blood-compatibility. Surface treated samples were characterized by measurement of contact angle goniometer and electron spectroscopy for chemical analysis (ESCA). The contact angles on the gold-coated polymeric surfaces decreased from 95-65 degrees to around 50 degrees, i.e., increased hydrophilicity due to incorporation of gold thin layer. From the results of ESCA analysis of the modified polymeric surfaces, surface modification by the gold-sputter method was successfully performed. Morphology of the adhered platelets on the gold-coated polymeric surfaces showed lesser activating than control, and the number of adhered platelets surface modified samples decreased with decreasing water contact angle. Fibroblast cell adhesion and growth on the gold-coated polymeric surfaces were more active than those of control. It seems that surface wettability and surface chemistry of gold play important roles for platelet adhesion and cell adhesion, spreading and growth.

3T3 Cells↗
PubMed1997

Cell and platelet adhesions on plasma glow discharge-treated poly(lactide-co-glycolide).

Surface treatment, such as plasma glow discharge treatment, onto poly(lactide-co-glycolide) (PLGA) has been investigated to improve the cell-, tissue- and blood-compatibility. Surface-treated samples were characterized by measurement with a contact angle goniometer and electron spectroscopy for chemical analysis (ESCA). The contact angles on the plasma-treated PLGA surfaces decreased with increasing plasma exposure time from 92 degrees to about 30 degrees, i.e., increased hydrophilicity. From the results of ESCA analysis of plasma-treated films, the incorporation of oxygen molecules into plasma onto the PLGA surface was observed. Cell adhesion and growth on plasma-treated PLGA surfaces were more active than on the control. Furthermore, the maximum adhesion and growth of cells in moderate hydrophilicity were investigated. Morphology of the adhered platelets on the plasma-treated PLGA surface showed less activity than on the control, and the number of adhered platelets on the plasma-exposed PLGA sample decreased with decreasing water contact angle. It seems that surface wettability of PLGA plays an important role in cell adhesion, spreading and growth, and platelet adhesion.

3T3 Cells↗
PubMed1996

Cloning and characterization of one member of the chalcone synthase gene family from Solanum tuberosum L.

We have isolated a chalcone synthase gene 2 (ST-CHS2) from potato by rapid amplification of cDNA ends by PCR. CHS2 cDNA had high homology to tomato LET-CHS2 (98%), petunia PHCHSJ (94%), potato ST-CHS1B (92%), petunia PHCHSA (92%), and LET-CHS1 (90%) at the overall 389-amino acid level. Genomic hybridization analysis indicated that CHS genes of potato comprise a family of at least six individual members.

Acyltransferases↗
PubMed1989

[An investigation on the oral surgery patients and their treatments].

The author has studied on the various diseases occurring in the oral and maxillofacial region for the year of 1987 at the Department of Oral & Maxillofacial Surgery, Seoul National University Hospital. The diseases diagnosed and treated have been analyzed according to each disease such as inflammatory, traumatic, cyst, tumor, neoplastic, deformities and so on, in order to get accurate information on the diseases of the oral & maxillofacial region and the information might be helpful to plan the education programmes for students, and interns and residents. The results obtained are as follows; 1. The sex distinction and the percentage of occurrence rate as follow Male 2090 (49.6%) Female 2127 (50.4%) 2. To study compare with the age, both male and female patients showed the highest ratio at the 20-29 age group, and the percentage of the 20-49 age group is 64.1% and the percentage of geriatric patients over 60 years old is 10.2%. 3. To study compare with the month (the patient came first time), August was most abundant in a year. 4. To study compare with the disease, dental-periodontal disease, impacted tooth and eruption abnormality are the most prevalent (51.2%), and next is odontogenic infection (22.4%), cyst & tumor (7.6%), traumatic injury (7.5%), and anomaly or deformity (3.8%). The number of medically compromised patients with oral surgery problems is 183 (4.3%). 5. Classifying the treatments according to the operator group, 1) For students(senior class), simple extraction showed the highest ratio, next is surgical extraction. 2) For interns, simple extraction showed the highest ratio, next is surgical extraction, pre-prosthetic surgery (alveoloplasty and vestibuloplasty).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗