Programmable DNA-Based Boolean Logic Microfluidic Processing Unit.

As molecular computing materials, information-encoded deoxyribonucleic acid (DNA) strands provide a logical computing process by cascaded and parallel chain reactions. However, the reactions in DNA-based combinational logic computing are mostly achieved through a manual process by adding desired DNA molecules in a single microtube or a substrate. For DNA-based Boolean logic, using microfluidic chips can afford automated operation, programmable control, and seamless combinational logic operation, similar to electronic microprocessors. In this paper, we present a programmable DNA-based microfluidic processing unit (MPU) chip that can be controlled via a personal computer for performing DNA calculations. To fabricate this DNA-based MPU, polydimethylsiloxane was cast using double-sided molding techniques for alignment between the microfluidics and valve switch. For a uniform surface, molds fabricated using a three-dimensional printer were spin-coated by a polymer. For programming control, the valve switch arms were operated by servo motors. In the MPU controlled via a personal computer or smartphone application, the molecules with two input DNAs and a logic template DNA were reacted for the basic AND and OR operations. Furthermore, the DNA molecules reacted in a cascading manner for combinational AND and OR operations. Finally, we demonstrated a 2-to-1 multiplexer and the XOR operation with a three-step cascade reaction using the simple DNA-based MPU, which can perform Boolean logic operations (AND, OR, and NOT). Through logic combination, this DNA-based Boolean logic MPU, which can be operated using programming language, is expected to facilitate the development of complex functional circuits such as arithmetic logical units and neuromorphic circuits.

Assessment of the dietary intake of propylene glycol in the Korean population.

An improved method for the analysis of propylene glycol (PG) in foods using a gas chromatography-flame ionisation detector (GC-FID), with confirmation by GC-MS, was validated by measuring several analytical parameters. The PG concentrations in 1073 products available in Korean markets were determined. PG was detected in 74.1% of the samples, in a concentration range from the limit of detection (n.d., 0.39 µg ml(-1)) to 12,819.9 mg kg(-1). The Korea National Health and Nutrition Examination Survey (KNHANES) 2011-2013 reported the mean intake levels of PG from all sources by the general population and consumers were 26.3 mg day(-1) (0.52 mg kg(-1) day(-1)) and 34.3 mg day(-1) (0.67 mg kg(-1) day(-1)), respectively. The 95th percentile intake levels of the general population and consumers were 123.6 mg day(-1) (2.39 mg kg(-1) day(-1)) and 146.3 mg day(-1) (2.86 mg kg(-1) day(-1)), respectively. In all groups of the general population, breads were the main contributors to the total PG intake. These reports provide a current perspective on the daily intake of PG in the Korean population.

Comparison of dietary food and nutrient intakes by supplement use in pregnant and lactating women in Seoul.

This study was performed to compare the dietary food and nutrient intakes according to supplement use in pregnant and lactating women in Seoul. The subjects were composed of 201 pregnant and 104 lactating women, and their dietary food intake was assessed using the 24-h recall method. General information on demographic and socioeconomic factors, as well as health-related behaviors, including the use of dietary supplements, were collected. About 88% and 60% of the pregnant and lactating women took dietary supplements, respectively. The proportion of dietary supplements used was higher in pregnant women with a higher level of education. After adjusting for potential confounders, among the pregnant women, supplement users were found to consume 45% more vegetables, and those among the lactating women were found to consume 96% more beans and 58% more vegetables. The intakes of dietary fiber and ß-carotene among supplement users were higher than those of non-users, by 23% and 39%, respectively. Among pregnant women, the proportion of women with an intake of vitamin C (from diet alone) below the estimated average requirements (EAR) was lower among supplement users [users (44%) vs. non-users (68%)], and the proportion of lactating women with intakes of iron (from diet alone) below the EAR was lower among supplement users [usesr (17%) vs. non-users (38%)]. These results suggest that among pregnant and lactating women, those who do not use dietary supplements tend to have a lower intake of healthy foods, such as beans and vegetables, as well as a lower intake of dietary fiber and ß-carotene, which are abundant in these foods, and non-users are more likely than users to have inadequate intake of micro-nutrient such as vitamin C and iron.

Effects of repeated seafood consumption on urinary excretion of arsenic species by volunteers.

Arsenic (As) is a known human carcinogen and widely distributed in the environment. The main route of As exposure in the general population is through food and drinking water. Seafood harvested in Korea contains high-level organoarsenics such as arsenobetaine, arsenocholine, and arsenosugars, which are much less harmful than inorganic arsenics. However, for those who eat large amounts of seafood it is important to understand whether seafood consumption affects urinary levels of inorganic As metabolites such as arsenite, arsenate, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA). In this study we investigated urinary As metabolites (inorganic As, MMA[V], DMA[V]) and some biological indexes such as AST, GSH, GPX, lipid peroxidation, and uric acid in volunteer study subjects (seven males and nine females). Total urinary As metabolites were analyzed by the hydride generation method, followed by arsenic speciation using HPLC with ICP-mass spectrometry. Study subjects refrained from eating seafood for 3 days prior to the first urine collection and then ingested seafood daily for 6 consecutive days. The first voided urine of the morning was collected from each subject the first day of the consecutive 6 days of seafood ingestion but prior to the first seafood meal. The first voided urine of the morning was also collected on days 1, 2, 3, 4, 5, 6, 7, 10, and 14 after seafood ingestion. The daily mean intake of total As was 6.98 mg, comprised of 4.71 mg of seaweed (67%), 1.74 mg of flat fish (25%), and 0.53 mg of conch (8%). We observed a substantial increase in total urinary As metabolites for subjects consuming seafood from day 1, which recovered to control level at day 10. The increase in total urinary As metabolites was attributed to the increase in DMA, which is a more harmful metabolite than organoarsenics. However, no significant changes in response biological indexes were observed. These results suggest that it is necessary to evaluate As metabolism when assessing the exposure to inorganic As and potential chronic health effects of seafood consumption in Korea.

Physiological difference between dietary obesity-susceptible and obesity-resistant Sprague Dawley rats in response to moderate high fat diet.

The primary aim of the present study was to define central and peripheral physiological differences between dietary obesity-susceptible (DOS) and obesity-resistant (DOR) outbred Sprague Dawley (SD) rats when given a moderate high fat diet containing 32.34% of energy as a fat. After a 9-week feeding period, the DOS-SD rats consumed significantly more feed (11.1%) and had higher abdominal (39.9%) and epididymal (27.5%) fat pads than the DOR-SD rats. In addition, serum leptin and insulin levels were significantly increased in the DOS-SD rats compared with those in the DOR-SD rats. However, we did not observe significant differences in serum triglyceride, cholesterol and glucose. No differences in hypothalamic OB-Ra and Rb mRNA expressions were found between the two groups. In contrast, arcuate NPY immunohistochemical expression was much higher in the DOS-SD rats than in the DOR-SD rats, though NPY expression in the supraoptic and paraventricular nuclei was not different between the two phenotypes. In peripheral tissues, the DOS-SD rats showed noticeably increased acetyl CoA carboxylase (ACC) mRNA expression in the liver, not epididymal fat. However, Western blot of peroxisomal proliferator activated factor gamma (PPAR gamma) in the liver and epididymal fat was not different between the two phenotypes of SD rats. It was concluded that different body weight phenotypes within outbred SD population responded differently to the development of dietary induced obesity via altered anabolic features in the hypothalamus and liver.