Effects of a controlled freeze-thaw event on dissolved and colloidal soil organic matter.

This study investigated the effects of the freezing and thawing that accompany the warming process on the composition of the soil organic matter in the dissolved and colloidal fractions. Temperate soil samples were incubated in a refrigerator at 2 °C for 4 weeks and compared with those frozen at -20 °C in the second week followed by thawing at 2 °C to study a freeze-thaw effect with minimal effect from the thawing temperature. The freeze-thaw group was compared with those incubated at 25 °C in the last week to investigate a warming effect after thawing. Thawing at 2 °C after freezing at -20 °C increased the dissolved organic carbon (DOC), but decreased colloidal Ca. The subsequent warming condition greatly increased both DOC and colloidal Ca. The colloidal organic carbon (COC) and dissolved Ca showed rather subtle changes in response to the freeze-thaw and warming treatments compared to the changes in DOC and colloidal Ca. The fluorescence excitation-emission matrix (EEM) and Fourier transformation-infrared spectrometry (FT-IR) results showed that the freeze-thaw and warming treatments gave the opposite effects on the compositions of dissolved humic-like substances, polysaccharides or silicates, and aliphatic alcohols. A principal component analysis (PCA) with the DOC, fluorescence EEM, and FT-IR spectra produced two principal components that successfully distinguished the effects of the freeze-thaw and warming treatments. Due to the contrasting effects of the freeze-thaw and warming treatments, the overall effects of freeze-thaw events in nature on the dissolved and colloidal soil organic matter could vary depending on the thawing temperature.

Diversity of bacteriophages infecting Xanthomonas oryzae pv. oryzae in paddy fields and its potential to control bacterial leaf blight of rice.

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a very serious disease in rice-growing regions of the world. In spite of their economic importance, there are no effective ways of protecting rice plants from this disease. Bacteriophages infecting Xoo affect the population dynamics of the pathogen and consequently the occurrence of the disease. In this study, we investigated the diversity, host range, and infectivity of Xoo phages, and their use as a bicontrol agent on BLB was tested. Among the 34 phages that were isolated from floodwater in paddy fields, 29 belonged to the Myoviridae family, which suggests that the dominant phage in the ecosystem was Myoviridae. The isolated phages were classified into two groups based on plaque size produced on the lawn of Xoo. In general, there was a negative relationship between plaque size and host range, and interestingly the phages having a narrow host range had low efficiency of infectivity. The deduced protein sequence analysis of htf genes indicated that the gene was not a determinant of host specificity. Although the difference in host range and infectivity depending on morphotype needs to be addressed, the results revealed deeper understanding of the interaction between the phages and Xoo strains in floodwater and damp soil environments. The phage mixtures reduced the occurrence of BLB when they were treated with skim milk. The results indicate that the Xoo phages could be used as an alternative control method to increase the control efficacy and reduce the use of agrochemicals.

Analysis of the Prevalence and Risk Factors of Malnutrition among Hospitalized Patients in Busan.

This study investigated the prevalence of and risk factors for malnutrition in hospitalized patients in Busan, Republic of Korea. 944 patients (440 men and 504 women) were hospitalized in four Busan general hospitals from March through April, 2011. Nutritional status was assessed on admission by the Nutritional Risk Screening 2002. Data were collected from the electronic medical records system for the characteristics of the subjects, clinical outcomes, biochemical laboratory data, and nutrition support states. Clinical dietitians interviewed the patients using structured questionnaires involving data on weight loss and problems related to oral intakes. Malnourished patients were significantly older (P<0.001) than well-nourished patients, but the values for BMI, serum albumin, total cholesterol, TLC, hemoglobin, and hematocrit were significantly lower (P<0.001) for malnourished than for well-nourished patients. Logistic regression indicated that the main determinant factors for nutritional status were the age, length of stay, BMI, serum albumin, and total cholesterol. In order to increase therapeutic effects of hospitalized patients, clinical dietitians need to offer proper nutritional intervention based on the results of nutrition assessment and identification of malnutrition.

Neuroprotective effects of Eucommia ulmoides Oliv. Bark on amyloid beta(25-35)-induced learning and memory impairments in mice.

In the present study, we examined whether aqueous extract of Eucommia ulmoides Oliv. Bark (EUE) with graded doses exerted its neuroprotective effects on amyloid beta(25-35) (Aß(25-35))-induced learning and memory impairments in mice. Mice received a single intracerebroventricular (i.c.v.) injection of Aß(25-35) 6 nmol as the critical factor in Alzheimer's disease (AD), cognition was evaluated using Y-maze, passive avoidance, and Morris water maze tests. EUE significantly improved the Aß(25-35)-induced memory deficit in the Y-maze test. Also, EUE increased step-through latency time with Aß(25-35)-induced learning and memory deficits in the passive avoidance test. In addition, EUE decreased the escape latencies with Aß(25-35)-induced cognitive impairments in the Morris water maze test. In the probe trial session, EUE increased time spent in the target quadrant. In the in vitro study, EUE was found to inhibit acetylcholinesterase (AChE) activity in a dose-dependent manner (IC50 value; 172 µg/ml). Ex vivo study, EUE significantly inhibited AChE activity in the hippocampus and frontal cortex. These results demonstrate that EUE possesses potent neuroprotective effects and that its beneficial effects are mediated, in part, by AChE inhibition, and therefore, might be a potential candidate in neurodegenerative diseases such as AD.

Neuroprotective effects of chlorogenic acid on scopolamine-induced amnesia via anti-acetylcholinesterase and anti-oxidative activities in mice.

Chlorogenic acid is a major polyphenolic component of many plants and beverages, and is particularly abundant in coffee. We evaluated the neuroprotective effects of chlorogenic acid on learning and memory impairment induced by scopolamine (0.5 mg/kg, i.p.), a muscarinic antagonist, using the Y-maze, passive avoidance, and Morris water maze tests. The chlorogenic acid significantly improved the impairment of short-term or working memory induced by scopolamine in the Y-maze test, and significantly reversed cognitive impairments in mice as measured by the passive avoidance test. In addition, chlorogenic acid decreased escape latencies in the Morris water maze test. In a probe trial session, chlorogenic acid increased the latency time in the target quadrant in a dose-dependent manner. Ex vivo, chlorogenic acid inhibited acetylcholinesterase activity in the hippocampus and frontal cortex. Chlorogenic acid also decreased malondialdehyde levels in the hippocampus and frontal cortex. In vitro, chlorogenic acid was found to inhibit acetylcholinesterase activity (IC50=98.17 µg/ml) and free radical scavenging activity (IC50=3.09 µg/ml) in a dose-dependent manner. These results indicate that chlorogenic acid may exert anti-amnesic activity via inhibition of acetylcholinesterase and malondialdehyde in the hippocampus and frontal cortex.

GABA(A) receptors mediate the attenuating effects of a 5-HT(3) receptor antagonist on methamphetamine-induced behavioral sensitization in mice.

We previously showed that 5-HT(3) receptors are involved in the development and expression of methamphetamine (MAP)-induced locomotor sensitization in mice. Here, we examined whether the dopaminergic or the GABAergic systems are involved in the attenuating effects of the 5-HT(3) receptor antagonist MDL72222 on MAP-induced locomotor sensitization. Quantitative autoradiography of D1 ([(3)H]SCH23390), D2 ([(3)H]raclopride) receptor, and GABA(A) receptor benzodiazepine ([(3)H]flunitrazepam) binding was carried out in the brains of mice treated with chronic MAP and pretreatment with MDL72222. No significant differences were found in D(1) and D(2) binding between the two groups, suggesting that the attenuating effects of MDL72222 on MAP-induced locomotor sensitization is not medicated by D1 and D2 receptors. Postsynaptic dopamine (DA) receptor supersensitivity was measured by challenge with apomorphine, a dopamine D(1) and D(2) receptor agonist, after repeated MAP treatment or pretreatment with MDL72222 before MAP. Apomorphine induced an enhanced locomotor activity in both chronic MAP-treated mice and mice pretreated with MDL 72222, with no significant differences between the two groups. The binding of [(3)H]flunitrazepam was significantly decreased in the motor and cingulate cortex, caudate putamen, and nucleus accumbens of mice in the repeated MAP treatment group compared with the control group, and this effect was reversed by pretreatment with MDL72222. This suggested that GABA(A) benzodiazepine binding sites are involved in the attenuating effects of a 5-HT(3) receptor antagonist on MAP-induced locomotor sensitization.

Epidemiological and genetic analysis of a sustained community-wide outbreak of hepatitis A in the Republic of Korea, 2008: a hospital-based case-control study.

BACKGROUND: The epidemiological shift of hepatitis A has contributed to a sustained community-wide outbreak in Korea during 2008. OBJECTIVES: To assess the risk factors associated with hepatitis A virus (HAV) propagation, and to analyze the circulating genotype in the sustained community-wide outbreak. STUDY DESIGN: The hospital-based case-control study was conducted in an 850-bed university hospital in Seoul from April to August, 2008. For molecular analysis of HAV isolates, a 488-bp gene fragment of the VP1 region was amplified and sequenced. RESULTS: In the multivariated logistic regression model, the risk factors of HAV infection adjusted by age were contacts with hepatitis A case (OR 3.98, 95% CI: 1.36-11.66), residence with child aged

Cancer mortality and farming in South Korea: an ecologic study.

OBJECTIVE: The aim of this study was to examine the geographical difference of cancer mortality to determine any potential associations between cancer mortality and farming in South Korea. METHODS: We calculated standardized mortality ratios (SMRs) based on age- and gender-specific cancer mortality rates for 245 geographic areas, using the registered death data from 2000 to 2004 that were obtained from the Korea National Statistical Office. Using the data from the Agriculture Census in 1995, we obtained the farming index. Poisson regression analysis was used to evaluate the associations between cancer mortality and farming after adjustment for socioeconomic factors. RESULTS: The SMR analyses based on 62,403 annual average cancer deaths yielded regional variations for all cancers combined in men (SMR = 70-192) and women (SMR = 80-132). With increasing farming index we found significantly elevated cancer mortality of esophagus, stomach, brain, and leukemia for men, and of esophagus and stomach for women, whereas the SMR for colorectal and gall bladder cancers were inversely associated with farming. The results were similar when the analyses were repeated after the exclusion of metropolitan areas. CONCLUSIONS: Our findings suggest a possible association between farming and mortality from a few cancer sites in South Korea.