Nong-Hoon Choe

Protective effects of ascorbic acid against lead-induced apoptotic neurodegeneration in the developing rat hippocampus in vivo

Lead is a neurotoxin that affects the developing central nervous system and may potentially induce apoptotic cell death. We investigated the effect of ascorbic acid against lead-induced neurotoxicity in the developing rat hippocampus. Female Sprague-Dawley rats were divided into three groups: control group, lead-treated group and lead plus ascorbic acid-treated group. Lead (0.2% lead acetate) was administered to female rats during pregnancy and lactation, in their drinking water. During this period, rats in the lead plus ascorbic acid-treated group received 100 mg/kg/day ascorbic acid, orally. At the end of the treatment, neuronal damage, apoptosis and blood lead levels were determined and the levels of Bax and Bcl-2 were immunodetected in the hippocampus of 21-day-old male pups. Histopathological evaluation demonstrated that ascorbic acid significantly attenuates apoptosis in the developing hippocampus and also spares hippocampal CA1, CA3 and dentate gyrus (DG) neurons. Simultaneous administration of ascorbic acid and lead lowered the level of Bax protein and increased Bcl-2 in pup hippocampus and reduced lead level in blood of dams compared with lead-treated only. Based on these results, it seems that ascorbic acid may potentially be beneficial in treating lead-induced brain injury in the developing rat brain.

Ascorbic acid ameliorates oxidative damage induced by maternal low-level lead exposure in the hippocampus of rat pups during gestation and lactation.

This study was to investigate the effects of ascorbic acid on the hippocampus of suckling rats in the presence of lead (Pb)-induced oxidative stress. Pregnant Sprague-Dawley rats received treatment with drinking water, divided into three groups, as follows: (1) distilled water; (2) 0.2% Pb; (3) 0.2% Pb+ascorbic acid (100mg/kg/day). Rat pups were euthanized at the age of 21days and their brain tissue was examined using light microscopy. Protein levels of Cu/Zn superoxide dismutase (Cu/Zn SOD), manganese superoxide dismutase (Mn SOD), and catalase (CAT) in the hippocampus were determined by Western blotting. We found a significant decrease in levels of Cu/Zn SOD and Mn SOD among Pb-exposed pups. Ascorbic acid supplementation appeared to negate the decrease in protein levels for Cu/Zn SOD and Mn SOD. In the case of CAT, there was no effect from Pb administration alone and Pb plus ascorbic acid appeared to increase the levels. In histopathology, ascorbic acid decreased the number of damaged cells in cornu ammonis areas CA1, CA3, and the dentate gyrus (DG) in hippocampus. Our results showed that administration of ascorbic acid during pregnancy and lactation could ameliorate some of the oxidative damage induced by Pb exposure in the developing rat hippocampus.

Evaluation of changes induced by temperature, contact time, and surface in the efficacies of disinfectants against avian influenza virus

Avian influenza viruses (AIV) are highly susceptible to all disinfectants because they are enveloped viruses. Disinfectants effective against AIV have optimum efficacies at temperatures above 20°C. Very few studies on effective disinfectants at low temperatures have been done. Disinfectants were investigated at 4 different temperatures (25, 4, 0, and -10°C) and 2 contact times (1 and 5 min) with suspension tests. Virucidal activity of the disinfectants was evaluated by carrier tests (wood and stainless steel) at 25 and -10°C. The concentration of each disinfectant for efficient disinfection within a short time (<1 min) at 25 and -10°C was also reestablished. The results from the suspension test indicated that low temperatures inhibited the virucidal efficacy of citric acid (CA) and CA + quaternary ammonium compounds (CA+ QAC) for 1 and 5 min, whereas the remaining disinfectants were effective, regardless of the short contact times and low temperatures. The carrier test results suggested that dried virus on wood was more difficult to inactivate compared with that on stainless steel. However, sodium dichloroisocyanurate and glutaraldehyde could inactivate AIV on both wood and stainless steel at -10°C. Citric acid-based agents could not sufficiently inactivate AIV at -10°C; however, the limitation due to low temperatures was overcome by adjusting disinfectant concentration. For a successful disinfection during winter, the disinfectants that could have short contact times with optimum efficacy against the target organism should be selected.

The rate of Salmonella spp. infection in zoo animals at Seoul Grand Park, Korea

Salmonellosis is an important zoonotic disease that affects both people and animals. The incidence of reptile-associated salmonellosis has increased in Western countries due to the increasing popularity of reptiles as pets. In Korea, where reptiles are not popular as pets, many zoos offer programs in which people have contact with animals, including reptiles. So, we determined the rate of Salmonella spp. infection in animals by taking anal swabs from 294 animals at Seoul Grand Park. Salmonella spp. were isolated from 14 of 46 reptiles (30.4%), 1 of 15 birds (6.7%) and 2 of 233 mammals (0.9%). These findings indicate that vigilance is required for determining the presence of zoonotic pathogen infections in zoo animals and contamination of animal facilities to prevent human infection with zoonotic diseases from zoo facilities and animal exhibitions. In addition, prevention of human infection requires proper education about personal hygiene.

Radiographic and computed tomographic evaluation of experimentally induced lung aspiration sites in dogs.

This study was performed to radiographically examine the prevalence of aspiration sites and to evaluate their atomical correlation with the bronchial pattens. Ten healthy beagle dogs were repeatedly radiographed, at weekly intervals, in the left and right lateral, ventrodorsal (VD) and dorsoventral (DV) positions. Three mililiters of iohexol distilled with same volume of saline was infused into the tracheal inlet. Which lung lobe was aspirated was decided upon by the presence of a significant alveolar pattern due to the contrast medium. Alveolar patterns were identified at the left (100%) and right cranial lung lobes (77%) with the dogs in dependant lateral recumbency, at the right caudal lung lobe (71%) with the dogs in VD recumbency and at the right middle lung lobe (59%) with the dogs in DV recumbency, respectively. The anatomical correlation was evaluated by performing computed tomography. The right principal bronchus (165.8 ± 1.6°) was more straightly bifurcated than was the left principal bronchus (142.7 ± 1.8°, p < 0.01). In VD position, the right side lung had a greater opertunity to become aspirated. The ventrally positioned right middle lobar bronchial origin was more easily to be aspirated the other laterally positioned ones. We think that these anatomical characteristics can be one of the causes for aspiration pneumonia to occur more frequently in the right side lung.

Prevalence of yeast-like fungi and evaluation of several virulence factors from feral pigeons in Seoul, Korea.

Aims:  Studies of pigeon‐borne yeasts have tended to focus on species, such as Cryptococcus neoformans and Candida albicans, with scant attention to feral pigeons in Korea. We studied the prevalence of yeasts from faecal samples of feral pigeons obtained in various public places in Seoul, Korea, and assessed their potential capacity as human pathogens.

Molecular identification of duck and quail common cytokine receptor γ chain genes

Common cytokine receptor γ chain (γ(c)) family cytokines play crucial roles in the regulation of innate and adaptive immune responses. Unlike mammals, chickens possess two different γ(c) transcripts. To determine if this difference is present in other avian species, γ(c) cDNA and genomic clones from ducks and quails were investigated. Two different γ(c) transcripts were identified in both species and designated as duck γ(c)-a (duγ(c)-a), duγ(c)-b, quail γ(c)-a (quγ(c)-a), and quγ(c)-b. Comparisons between the duck and quail γ(c) cDNA and genomic sequences indicated that the two transcripts were produced by alternative splicing. Unexpectedly, the duγ(c)-b contained the fifth intron, a frame-switching 88-bp insertion, resulting in a receptor molecule lacking a transmembrane region. These findings indicate a possibility that avian species, unlike mammals, express two different γ(c) transcripts due to alternative splicing. This study is the first demonstration of an alternatively spliced γ(c) isoform that lacks a transmembrane domain.

Silk fibroin has a protective effect against high glucose induced apoptosis in HIT‐T15 cells

High glucose levels induce cell death in many cell types, including pancreatic β‐cells. Although protective agents against glucotoxicity have been searched for extensively, so far none have been found. In this report, we tested silk fibroin (SF) as a candidate material for antiglucotoxicity in the pancreatic β‐cell (HIT‐T15 cell) line. Approximately 50% of cells were killed after treatment with 80 mg/mL glucose. This reduction of cell number was recovered by the addition of SF at 50 mg/mL. SF treatment also decreased cellular reactive oxygen species (ROS) and increased proliferating cellular nuclear antigen (PCNA) immunoreactivity. In addition, TUNEL assays demonstrated that SF protects against glucose‐induced apoptosis of HIT‐T15 cells, suggesting that SF might protect cells from cell death by lowering cellular ROS levels. SF also induced expression of the insulin‐like growth factor‐1 (IGF‐1) gene, and IGF‐1 expression may be the cause of SF‐induced protection against glucose toxicity. Taken together, these results suggest that SF could serve as a potential therapeutic agent to treat the hyperglycemia‐induced death of pancreatic β‐cells.

Seroprevalence of Coxiella burnetii in cattle and farm- raised deer in Korea

Q fever, caused by Coxiella burnetii, is a worldwide zoonosis that affects not wild animals but domestic animals throughout the world, except in New Zealand. Domestic ruminants are considered to be a major infection source of Q fever in humans. However, few studies on the prevalence of Q fever in humans or animals in Korea have been conducted. Thus, the aim of this study was to investigate the seroprevalence of Q fever in meat cattle and deer. Blood samples were collected from 1634 ruminants: 1000 cattle, 604 wapiti, and 30 sika deer. The blood samples were analyzed with CHEKIT Q fever ELISA kits. Thirteen of 1000 (1.3%) cattle, 10 of 604 (about 1.7%) wapiti, and 0 of 30 (0%) sika deer had antibodies against C. burnetii. The prevalence of Q fever in this study was quite low. However, the public health implications of these findings are important, because they indicate that seropositive animals that are asymptomatic may be shedding C. burnetii consistently. This condition could increase the risk of Q fever infection in Korea, especially because many Koreans habitually consume raw meat and drink deer blood.

Inactivation of Salmonella on Eggshells by Chlorine Dioxide Gas

Microbiological contamination of eggs should be prevented in the poultry industry, as poultry is one of the major reservoirs of human Salmonella. ClO2 gas has been reported to be an effective disinfectant in various industry fields, particularly the food industry. The aims of this study were to evaluate the antimicrobial effect of chlorine dioxide gas on two strains of Salmonella inoculated onto eggshells under various experimental conditions including concentrations, contact time, humidity, and percentage organic matter. As a result, it was shown that chlorine dioxide gas under wet conditions was more effective in inactivating Salmonella Enteritidis and Salmonella Gallinarum compared to that under dry conditions independently of the presence of organic matter (yeast extract). Under wet conditions, a greater than 4 log reduction in bacterial populations was achieved after 30 min of exposure to ClO2 each at 20 ppm, 40 ppm, and 80 ppm against S. Enteritidis; 40 ppm and 80 ppm against S. Gallinarum. These results suggest that chlorine dioxide gas is an effective agent for controlling Salmonella, the most prevalent contaminant in the egg industry.