Effects of Particulate Matter Exposure on the Eustachian Tube and Middle Ear Mucosa of Rats

OBJECTIVES

Particulate matter (PM) is a risk factor for various diseases. Recent studies have established an association between otitis media (OM) and PM exposure. To confirm this relationship, we developed a novel exposure model designed to control the concentration of PM, and we observed the effects of PM exposure on the Eustachian tube (ET) and middle ear mucosa of rats.

METHODS

Forty healthy, 10-week-old, male Sprague-Dawley rats were divided into 3-day, 7-day, 14-day exposure, and control groups (each, n=10). The rats were exposed to incense smoke as the PM source for 3 hours per day. After exposure, bilateral ETs and mastoid bullae were harvested, and histopathological findings were compared using microscopy and transmission electron microscopy (TEM). The expression levels of interleukin (IL)-1β, IL-6, tumor necrosis factor-α, and vascular endothelial growth factor (VEGF) in the middle ear mucosa of each group were compared using real-time reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

In the ET mucosa of the exposure group, the goblet cell count significantly increased after PM exposure (P=0.032). In the middle ear mucosa, subepithelial space thickening, increased angio-capillary tissue, and inflammatory cell infiltration were observed. Moreover, the thickness of the middle ear mucosa in the exposure groups increased compared to the control group (P<0.01). The TEM findings showed PM particles on the surface of the ET and middle ear mucosa, and RT-PCR revealed that messenger RNA (mRNA) expression of IL-1β significantly increased in the 3-day and 7-day exposure groups compared to the control group (P=0.035). VEGF expression significantly increased in the 7-day exposure group compared to the control and 3-day exposure groups (P<0.01).

CONCLUSION

The ET and middle ear mucosa of rats showed histopathologic changes after acute exposure to PM that directly reached the ET and middle ear mucosa. Therefore, acute exposure to PM may play a role in the development of OM.

Preliminary study on the effect of using heat-not-burn tobacco products on indoor air quality

In this study, the effect of the use of heat-not-burn (HnB) products on indoor air quality (IAQ) was evaluated. To do this, the concentrations of nicotine, propylene glycol (PG), and vegetable glycerin (VG) directly emitted when using HnB products were analyzed and compared to those from conventional cigarettes. Furthermore, the levels of VOCs, aldehydes, nanoparticle, and particulate matter (PM) detected when subjects used HnB products in the exposure chamber were evaluated the effect on IAQ. As a result, the range of nicotine levels transferred by HnB products (0.8-1.2 mg cigarette^-1) is lower than that by conventional cigarettes (2.4-3.6 mg cigarette^-1). On the other hand, the range of VG levels emitted from HnB products (3.1-5.9 mg cigarette^-1) were higher than that emitted from conventional cigarettes (0.6-3.0 mg cigarette^-1). In addition, although the amount generated from HnB products was small compared to those from conventional cigarettes, various kinds of VOCs, aldehydes, nanoparticle and PM were produced, and these were confirmed to affect IAQ.

Volatile organic compounds released in the mainstream smoke of flavor capsule cigarettes

In this study, the composition of mainstream smoke was investigated with an emphasis on a list of volatile organic compounds (VOCs: e.g., isoprene, acrylonitrile, methyl ethyl ketone, benzene, toluene, m-xylene and styrene) using the two types of flavor capsule cigarettes (FCCs, here coded as F1 and F2) in reference to one commercial, non-flavored (NF) and 3R4F cigarette. The concentrations of all the target compounds from FCCs were quantified under two contrasting conditions (i.e., with and without breaking the capsules). The effect of breaking the capsule was apparent in the FCC products with the enhancement of VOC levels, specifically between after and before breaking the capsules (e.g., 1.10-1.58 folds (benzene) and 1.30-1.53 folds (acetonitrile)). Such increases were apparent in both FCC samples if assessed in terms of the total amount of VOCs (TVOC): (1) F1 (from 2159 to 2530 μg cig-1 (p = 9.42 × 10-6)) and (2) F2 (from 1470 to 2014 μg cig-1 (p = 0.05)). In addition, these TVOC levels determined from the FCCs were 1.62- to 1.83- and 1.29- to 1.46-fold higher than those of the NF cigarette and the 3R4F cigarette, respectively. Thus, these FCC products are suspected to play a role as stronger sources of VOCs than the general cigarette products.

Decomposition of n-hexane using a dielectric barrier discharge plasma

In this study, we investigated the decomposition characteristics of n-hexane by a dielectric barrier discharge (DBD) plasma. In order to accomplish this, the factors influencing these decomposition characteristics such as background gases (air, N₂, and He), residence time (1-10 s), initial n-hexane concentration (10-50 ppm), relative humidity (2.5%, 40%, and 70%), and power (50-80 W) were evaluated. As a result, the decomposition efficiency of n-hexane at N₂ atmosphere was found to be lower than those at air and He atmosphere. The removal efficiency of n-hexane was increased when the residence time, relative humidity, and power increased, and when the initial concentration decreased. The concentrations of CO, CO₂, and aerosol increased as the specific energy density increased. However, the O₃ level increased up to a certain point, then decreased. Various hydrocarbons such as acetone, pentanal, nonanal, etc. were also detected as by-products and their decomposition and recombination pathways were suggested.

A Potential Approach to Compensate the Gas Interference for the Analysis of NO by a Non-dispersive Infrared Technique

Interference is a pivotal issue of a non-dispersive infrared (NDIR) sensor and analyzer. Therefore, the main contribution of this study is to introduce a potential method to compensate for the interference of the NDIR analysis. A potential method to compensate for the interference of a nitric oxide (NO) NDIR analyzer was developed. Double bandpass filters (BPFs) with HITRAN (high-resolution transmission molecular absorption database)-based wavelengths were used to create an ultranarrow bandwidth, where there were least-interfering effects with respect to the coal-fired power plant emission gas compositions. Key emission gases from a coal-fired power plant, comprising carbon monoxide (CO), NO, sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon dioxide (CO₂), and water (H₂O) (in the form of vapor), were used to investigate the gas interference. The mixtures of those gases were also used to investigate the performance of the double BPFs. We found that CO, CO₂, SO₂, and H₂O significantly affected the detection of NO when a commercial, single narrow BPF was used. In contrast, the double BPFs could remove the interference of CO, NO₂, SO₂, and CO₂ in terms of their concentrations. In the case of H₂O, the filter performed well until a level of 50% relative humidity at 25 °C. Moreover, the signal-to-noise ratio of the analyzer was approximately 10 when the double BPFs were applied. In addition, the limit of detection of the analyzer with the double BPFs was approximately 4 ppm, whereas that with the commercial one was 1.3 ppm. Therefore, double BPFs could be used for an NO NDIR analyzer instead of a gas filter correlation to improve the selectivity of the analyzer under the condition of a known gas composition, such as a coal-fired power plant. However, the sensitivity of the analyzer would be decreased.

An efficient tool for the continuous monitoring on adsorption of sub-ppm level gaseous benzene using an automated analytical system based on thermal desorption-gas chromatography/mass spectrometry approach

It became an important task to effectively adsorb volatile organic compounds (VOCs) at or near real-world levels for efficient control of airborne pollution in ambient environments. Nonetheless, most studies carried out previously for the control of VOCs are confined to significantly polluted conditions (e.g., >100 ppm) that are far different from real-world or ambient conditions. To help acquire the meaningful data for the adsorptive removal of VOCs at near real-world levels, a new approach was designed and implemented to measure adsorption of gaseous benzene (as a representative or model VOC) at trace-level quantities (as low as 0.14 ng (0.43 ppb) for a 100 mL sample) using activated carbon (sieved to 212 μm mesh size) as a model sorbent. With the aid of a thermal desorption-gas chromatography/mass spectrometry system, the key adsorption performance metrics (such as 10% breakthrough volume (10% BTV) points: 10% as the key reference) were determined: 1018 L atm g^-1 at 0.1 ppm benzene with the corresponding partition coefficient of 3.85 mol kg^-1 Pa^-1. If the adsorption capacity values (at 10% BTV) are compared across the varying concentration levels of benzene, the maximum value of 1.07 mg g^-1 was observed at 1 ppm benzene (within the concentration range selected in this work). As such, it was possible to quantitatively assess the sorbate-sorbent interactions at significantly low concentrations of VOCs that actually prevail under the near real-world conditions.

The effects of continuous- and stop-flow gas streams on adsorptive removal of benzene vapor using type - II covalent organic polymers

Various materials have been investigated for the adsorptive removal of volatile organic compounds (VOCs, such as benzene). However, most materials proposed for the adsorptive removal of gaseous benzene (and other VOCs) perform relatively poorly (e.g., an impractically low-service 10% breakthrough volume [BTV10] at < 100 ppm). The adsorbent uptake rate (mg g^-1 min^-1) can also be assessed as a function of the gas-stream flow rate (or space velocity). The main aim of this study is to explore the effect of two different gas-stream supply modes - stopped flow (at a fixed stream flow rate of 330 mL atm min^-1) vs. continuous flow (a variable-stream flow rate of 100, 200, or 330 mL atm min^-1) on the adsorption metrics of gaseous benzene on 5 mg of two types of - II covalent organic polymers (COPs: CBAP-1 [DETA], CD; or CBAP-1 [EDA], CE). The sorbent tube outlet stream was sampled by two respective sampling methods (i.e., a large-volume injector [LVI] for stopped flow vs. syringe injection [SI] for continuous flow) for sample quantitation by gas chromatography flame-ionization detection (GC-FID). The observed BTV10 values in the two sampling modes were similar when tested using 10 ppm benzene, irrespective of sorbents: 56/60 (CD) vs. 620/624 L atm g^-1 (CE). BTV10 values increased systematically with decreasing stream-flow rates to reflect the importance of space velocity in adsorptive removal of benzene. The overall assessment of adsorption performance between stopped flow (LVI) and continuous flow (SI) revealed that the performance of the adsorbent is independent of flow mode (e.g., when performance was compared at flow rate of 330 mL min^-1).

Quantitative insights into major constituents contained in or released by electronic cigarettes: Propylene glycol, vegetable glycerin, and nicotine

Generally, the liquid used in electronic cigarettes (E-cigarettes), which is also called E-liquid, is composed of propylene glycol (PG), vegetable glycerin (VG), and nicotine, with many other miscellaneous ingredients. E-liquid is consumed mainly in the form of aerosol via inhalation by the e-cigarette user. The amount and composition of the aerosol generated during its consumption depend on various factors. In this study, the three major constituents (PG, VG, and nicotine) of E-cigarettes were analyzed in both liquid and aerosol samples from 50 commercial products. Their concentrations in the liquid (and aerosol at 3.4 V) samples were 538 (4 6 7), 482 (4 4 9), and 8.75 mg g^-1 (7.91 mg g^-1), respectively. The nicotine levels in the E-liquids measured in this study were normally 1.2 times greater than those specified by the manufacturers. Furthermore, the amount of liquid consumed increased proportionally as the voltage of the E- cigarette increased. The consumption rate of VG increased as the voltage of the E-cigarette increased, whereas that of PG and nicotine decreased. The results of our study confirm that the amounts of PG and VG generated through the use of E-cigarettes are noticeably larger than those from other tobacco products (such as traditional tobaccos and heat-not-burn products), although no such trend was evident in case of nicotine.

The transfer characteristics of heavy metals in electronic cigarette liquid

In this research, the concentrations of six heavy metals (Zn, Pb, Ni, Fe, Cd, and Cr) in electronic cigarette (EC) solutions were determined to assess their association with EC use patterns. To this end, their contents were analyzed under three conditions: (1) ECL I: EC liquid was directly taken from EC liquid bottles as purchased from retail, (2) ECL II: EC liquid simply stored in the EC clearomizer for a certain period was collected without any puffing, and (3) ECL III: EC liquid remaining in the EC clearomizer after puffing. Each of all three types of electronic cigarette liquid (ECL) samples selected in this study was analyzed after being stored for up to seven days (at elapsed intervals of 1, 3, and 7 days). Zn and Pb were detected in all types of samples while Cd was all below method detection limit (MDL). Fe, Ni, and Cr were generally below MDL in ECL I, while it was not the case for ECL II and III samples. Especially, Zn, Pb, and Ni levels increased significantly with the use of EC. If the consumption of EC causes alterations in elemental content, such changes can be assessed in terms of ratio values such as "after/before use". The maximum ratio values for each target, when assessed using ECL III samples, were seen in the following order: 463 (Zn) > 315 (Ni) > 131 (Fe) > 47.9 (Cr) > 36.0 (Pb). As such, EC use is clearly demonstrated as the transfer route of heavy metals.

Development of a magnetic hybrid filter to reduce PM10 in a subway platform

This study investigated the reduction of particulate matter (PM) in a subway platform using self-developed magnetic hybrid filters (magnet-magnet (MM) and magnet-cascade (MC) filter). The magnetic hybrid filter systems were installed and operated in Jegi-dong subway station (J station) platform. The removal efficiency of PM₁₀ (particular matter with aerodynamic diameter less than 10 μm) was evaluated according to various influencing factors such as the combination of filters, linear velocity, and operating conditions of trains. As a result, the average removal efficiency of the MC filter (40.5%) was higher than that of the MM one (27.0%). The maximum PM₁₀ removal efficiencies by MM (34.1%) and MC (47.2%) filters were observed at 20 (linear velocity: 2.41 m/s) and 30 jog (8 m/s) dials, respectively. We additionally found that the removal efficiency of PM₁₀ using MM and MC filters suddenly decreased when the concentration of background PM₁₀ in the platform increased. Based on the results of this study, hybrid technology using two or more capture principles can remove PM more efficiently than technology using a single such principle.

A review of traditional and advanced technologies for the removal of particulate matter in subway systems

The pollution status of particulate matter (PM) in a subway system and technological trends in their reduction were discussed in this study. The levels of PM_2.5 and PM₁₀ are generally found to be higher in the underground platforms and tunnels than those in the outdoor air. It has also been reported that the composition of fine dust in the subway consists of various substances including heavy metals (like Fe), carbonaceous matter, and solvent extractable organic matter (SEOM). It was confirmed that subway dust was created mainly by wearing on wheels, rails, and brakes. In addition, the concentration of PM in such environment was influenced not only by internal factors (eg, operating conditions of trains and ventilation systems, number of passengers, and the structure of subway stations) but also by outside factors (eg, ambient air concentration). Up to now, various techniques (ventilation fans, platform screen doors (PSDs), magnetic filters, small jet fans, artificial intelligent ventilation systems, hybrid filters, etc) have been studied to reduce PM in underground subway systems. In this study, we reviewed the air quality of major subway stations with the focus on PM and relevant technologies for its reduction.

Nicotine, aerosol particles, carbonyls and volatile organic compounds in tobacco- and menthol-flavored e-cigarettes

BACKGROUND

We aimed to assess the content of electronic cigarette (EC) emissions for five groups of potentially toxic compounds that are known to be present in tobacco smoke: nicotine, particles, carbonyls, volatile organic compounds (VOCs), and trace elements by flavor and puffing time.

METHODS

We used ECs containing a common nicotine strength (1.8%) and the most popular flavors, tobacco and menthol. An automatic multiple smoking machine was used to generate EC aerosols under controlled conditions. Using a dilution chamber, we targeted nicotine concentrations similar to that of exposure in a general indoor environment. The selected toxic compounds were extracted from EC aerosols into a solid or liquid phase and analyzed with chromatographic and spectroscopic methods.

RESULTS

We found that EC aerosols contained toxic compounds including nicotine, fine and nanoparticles, carbonyls, and some toxic VOCs such as benzene and toluene. Higher mass and number concentrations of aerosol particles were generated from tobacco-flavored ECs than from menthol-flavored ECs.

CONCLUSION

We found that diluted machine-generated EC aerosols contain some pollutants. These findings are limited by the small number of ECs tested and the conditions of testing. More comprehensive research on EC exposure extending to more brands and flavor compounds is warranted.

Distinctive genomic signature of neural and intestinal organoids from familial Parkinson's disease patient-derived induced pluripotent stem cells

AIMS

The leucine-rich repeat kinase 2 (LRRK2) G2019S mutation is the most common genetic cause of Parkinson's disease (PD). There is compelling evidence that PD is not only a brain disease but also a gastrointestinal disorder; nonetheless, its pathogenesis remains unclear. We aimed to develop human neural and intestinal tissue models of PD patients harbouring an LRRK2 mutation to understand the link between LRRK2 and PD pathology by investigating the gene expression signature.

METHODS

We generated PD patient-specific induced pluripotent stem cells (iPSCs) carrying an LRRK2 G2019S mutation (LK2GS) and then differentiated into three-dimensional (3D) human neuroectodermal spheres (hNESs) and human intestinal organoids (hIOs). To unravel the gene and signalling networks associated with LK2GS, we analysed differentially expressed genes in the microarray data by functional clustering, gene ontology (GO) and pathway analyses.

RESULTS

The expression profiles of LK2GS were distinct from those of wild-type controls in hNESs and hIOs. The most represented GO biological process in hNESs and hIOs was synaptic transmission, specifically synaptic vesicle trafficking, some defects of which are known to be related to PD. The results were further validated in four independent PD-specific hNESs and hIOs by microarray and qRT-PCR analysis.

CONCLUSION

We provide the first evidence that LK2GS also causes significant changes in gene expression in the intestinal cells. These hNES and hIO models from the same genetic background of PD patients could be invaluable resources for understanding PD pathophysiology and for advancing the complexity of in vitro models with 3D expandable organoids.

Spatial Variability of AERONET Aerosol Optical Properties and Satellite Data in South Korea during NASA DRAGON-Asia Campaign

We investigated spatial variability in aerosol optical properties, including aerosol optical depth (AOD), fine-mode fraction (FMF), and single scattering albedo (SSA), observed at 21 Aerosol Robotic Network (AERONET) sites and satellite remote sensing data in South Korea during the spring of 2012. These dense AERONET networks established in a National Aeronautics and Space Administration (NASA) field campaign enabled us to examine the spatially detailed aerosol size distribution and composition as well as aerosol levels. The springtime particle air quality was characterized by high background aerosol levels and high contributions of coarse-mode aerosols to total aerosols. We found that between-site correlations and coefficient of divergence for AOD and FMF strongly relied on the distance between sites, particularly in the south-north direction. Higher AOD was related to higher population density and lower distance from highways, and the aerosol size distribution and composition reflected source-specific characteristics. The ratios of satellite NO2 to AOD, which indicate the relative contributions of local combustion sources to aerosol levels, represented higher local contributions in metropolitan Seoul and Pusan. Our study demonstrates that the aerosol levels were determined by both local and regional pollution and that the relative contributions of these pollutions to aerosols generated spatial heterogeneity in the particle air quality.

Volatile organic compounds (VOCs) in surface coating materials: Their compositions and potential as an alternative fuel

A sampling system was designed to determine the composition ratios of VOCs emitted from 31 surface coating materials (SCMs). Representative architectural, automotive, and marine SCMs in Korea were investigated. Toluene, ethylbenzene, and xylene were the predominant VOCs. The VOC levels (wt%) from automotive SCMs were significantly higher than those from architectural and marine paints. It was found that target SCMs comprised mainly VOCs with 6-10 carbon atoms in molecules, which could be adsorbed by activated carbon. The saturated activated carbon which had already adsorbed toluene, ethylbenzene, and m-xylene was combusted. The saturated activated carbon was more combustible than new activated carbon because it comprised inflammable VOCs. Therefore, it could be an alternative fuel when using in a "fuelization system". To use the activated carbon as a fuel, a control technology of VOCs from a coating process was also designed and introduced.

Emission characteristics of VOCs emitted from consumer and commercial products and their ozone formation potential

The characteristics of volatile organic compounds (VOCs) emitted from several consumer and commercial products (body wash, dishwashing detergent, air freshener, windshield washer fluid, lubricant, hair spray, and insecticide) were studied and compared. The spray products were found to emit the highest amount of VOCs (~96 wt%). In contrast, the body wash products showed the lowest VOC contents (~1.6 wt%). In the spray products, 21.6-96.4 % of the VOCs were propane, iso-butane, and n-butane, which are the components of liquefied petroleum gas. Monoterpene (C10H16) was the dominant component of the VOCs in the non-spray products (e.g., body wash, 53-88 %). In particular, methanol was present with the highest amount of VOCs in windshield washer fluid products. In terms of the number of carbon, the windshield washer fluids, lubricants, insecticides, and hair sprays comprised >95 % of the VOCs in the range C2-C5. The VOCs in the range C6-C10 were predominantly found in the body wash products. The dishwashing detergents and air fresheners contained diverse VOCs from C2 to C11. Besides comprising hazardous VOCs, VOCs from consumer products were also ozone precursors. The ozone formation potential of the consumer and commercial spray products was estimated to be higher than those of liquid and gel materials. In particular, the hair sprays showed the highest ozone formation potential.

Development of an activated carbon filter to remove NO2 and HONO in indoor air

To obtain the optimum removal efficiency of NO2 and HONO by coated activated carbon (ACs), the influencing factors, including the loading rate, metal and non-metal precursors, and mixture ratios, were investigated. The NOx removal efficiency (RE) for K, with the same loading (1.0 wt.%), was generally higher than for those loaded with Cu or Mn. The RE of NO2 was also higher when KOH was used as the K precursor, compared to other K precursors (KI, KNO3, and KMnO4). In addition, the REs by the ACs loaded with K were approximately 38-55% higher than those by uncoated ACs. Overall, the REs (above 95%) of HONO and NOx with 3% KOH were the highest of the coated AC filters that were tested. Additionally, the REs of NOx and HONO using a mixing ratio of 6 (2.5% PABA (p-aminobenzoic acid)+6% H3PO4):4 (3% KOH) were the highest of all the coatings tested (both metal and non-metal). The results of this study show that AC loaded with various coatings has the potential to effectively reduce NO2 and HONO levels in indoor air.

Installation of platform screen doors and their impact on indoor air quality: Seoul subway trains

In this study, variations of particulate matter (PM) concentrations in subway trains following installation of platform screen doors (PSDs) in the Seoul subway system were investigated. PM samples were collected in the trains on subway lines 1-8 before and after installation of PSDs. It was found that the mean PM10 concentration in the trains after PSDs installation increased significantly by 29.9% compared to that before installation. In particular, the increase of PM10 in line 6 was the highest at 103%. When the relationship between PM10 and PM2.5 was compared, coefficients of determination (r2) before and after PSDs installations were 0.696 and 0.169, respectively. This suggests that air mixing between the platform and the tunnel after PSDs installation was extremely restricted. In addition, the indoor/outdoor PM10 ratio following PSDs installation increased from 1.32 to 2.97 relative to the period with no installed PSDs. Furthermore, this study revealed that PM levels in subway trains increased significantly after all underground PSDs were put in use. Several potential factors were examined that could result in this PM increase, such as train ventilation systems, operational conditions, passenger volume, subway depth, and the length of underground segments. Implications: PM10 concentrations inside the subway trains increased after PSDs installation. This indicates that air quality in trains was very seriously impacted by PSDs. PM10 levels were also influenced by the tunnel depth and length of the underground segments. To prevent the adverse effect on human health by PM10 emitted from the tunnel, an applicable ventilation system to reduce PM10 is required inside trains and tunnels.

Effects of dietary levels of glycine, threonine and protein on threonine efficiency and threonine dehydrogenase activity in hepatic mitochondria of chicks

This study was carried out to evaluate the relationship between threonine (Thr) efficiency and Thr dehydrogenase (TDG) activity as an indicator of Thr oxidation on chicks fed with levels of diets (CP [17.5% and 21.5%] and Thr [3.8 and 4.7 g/100 g CP]; glycine [Gly][0.64% and 0.98%] and true digestible Thr [dThr] [0.45% and 0.60%]). Calculation of the Thr efficiency was based on N-balance data and an exponential N-utilization model, and TDG activity was determined as accumulation of aminoacetone and Gly during incubation of hepatic mitochondria. This study found that in the liver of chicks who received a diet containing up to 0.79% Thr (4.7 g Thr/100 g of CP) in the 17.5% CP diet, no significant (p>0.05) effect on TDG activity was observed. However, significantly (p = 0.014) increased TDG activity was observed with a diet containing 21.5% CP (4.7 g Thr/100 g of CP) and the efficiency of Thr utilization showed a significant (p = 0.001) decrease, indicating the end of the Thr limiting range. No significant (p>0.05) effect on the total TDG activity and accumulation of Gly was observed with addition of Gly to a diet containing 0.45% dThr. In addition, addition of Gly to a diet containing 0.60% dThr also did not result in a change in accumulation of Gly. Due to an increase in accumulation of aminoacetone, an elevated effect on total TDG activity was also observed. No significant (p>0.05) reduction in the efficiency of Thr utilization was observed after addition of Gly at the level of 0.45% dThr. However, significantly (p<0.001) reduced efficiency of Thr utilization was observed after addition of Gly at the level of 0.60% dThr. Collectively, we found that TDG was stimulated not only by addition of Thr and protein to the diet, but also by addition of Gly, and efficiency of Thr utilization was favorably affected by addition of Gly at the level near to the optimal Thr concentration. In addition, no metabolic requirement of Gly through the TDG pathway was observed with almost the same accumulation of Gly and a slight increase in TDG activity by addition of Gly. Thus, our findings suggest that determination of TDG activity and parameter of efficiency of Thr utilization may be useful for evaluation of dietary Thr level.

Removal of particulate matter emitted from a subway tunnel using magnetic filters

We removed particulate matter (PM) emitted from a subway tunnel using magnetic filters. A magnetic filter system was installed on the top of a ventilation opening. Magnetic field density was increased by increasing the number of permanent magnet layers to determine PM removal characteristics. Moreover, the fan's frequency was adjusted from 30 to 60 Hz to investigate the effect of wind velocity on PM removal efficiency. As a result, PM removal efficiency increased as the number of magnetic filters or fan frequency increased. We obtained maximum removal efficiency of PM10 (52%), PM2.5 (46%), and PM1 (38%) at a 60 Hz fan frequency using double magnetic filters. We also found that the stability of the PM removal efficiency by the double filter (RSD, 3.2-5.8%) was higher than that by a single filter (10.9-24.5%) at all fan operating conditions.

Chemical speciation of size-segregated floor dusts and airborne magnetic particles collected at underground subway stations in Seoul, Korea

Previous studies have reported the major chemical species of underground subway particles to be Fe-containing species that are generated from wear and friction processes at rail-wheel-brake and catenaries-pantographs interfaces. To examine chemical composition of Fe-containing particles in more details, floor dusts were collected at five sampling locations of an underground subway station. Size-segregated floor dusts were separated into magnetic and non-magnetic fractions using a permanent magnet. Using X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDX), iron metal, which is relatively harmless, was found to be the dominating chemical species in the floor dusts of the <25 μm size fractions with minor fractions of Mg, Al, Si, Ca, S, and C. From SEM analysis, the floor dusts of the <25 μm size fractions collected on railroad ties appeared to be smaller than 10 μm, indicating that their characteristics should somewhat reflect the characteristics of airborne particles in the tunnel and the platform. As most floor dusts are magnetic, PM levels at underground subway stations can be controlled by removing magnetic indoor particles using magnets. In addition, airborne subway particles, most of which were smaller than 10 μm, were collected using permanent magnets at two underground subway stations, namely Jegi and Yangjae stations, in Seoul, Korea. XRD and SEM/EDX analyses showed that most of the magnetic aerosol particles collected at Jegi station was iron metal, whereas those at Yangjae station contained a small amount of Fe mixed with Na, Mg, Al, Si, S, Ca, and C. The difference in composition of the Fe-containing particles between the two subway stations was attributed to the different ballast tracks used.

Seasonal variations of monoterpene emissions from Pinus densiflora in East Asia

The emission rates and compositions of monoterpene from Pinus densiflora were investigated in the Gumsung (GM) and Worak (WM) mountains. The standard emission rates (ERs: ERs is the monoterpene emission rate at standard temperature, 30 degrees C) from P. densiflora ranged from 0.817 to 1.704 (microgC/gdw-h). The ERs and beta-values of total monoterpene were measured at the two study sites (GM and WM). In the spring and summer, the ERs were the highest, while relatively low values (<0.058microgC/gdw-h) were measured in the autumn and winter. In GM and WM sites the beta-value obtained for the different seasons ranged from 0.047 to 0.179, with an average of 0.09. The major monoterpene compounds from P. densiflora were alpha-pinene, myrcene, beta-phellandrene, d-limonene and alpha-terpinene. The fractional compositions of individual monoterpene compounds were significantly different between the two test sites in the summer and winter. The ERs of the older group (31-40 years) were higher than those in the younger group (21-30 years). However, the monoterpene compositions were similar between the two age groups.

Perifusion model for detoxification of drugs in a bioartificial liver

Detoxification of a drug in a bioartificial liver (BAL) during an in vitro experiment was theoretically carried out based on a perifusion model. The detoxification capacity assay, the rates of disappearance of the chemicals such as flow-limited and enzyme-limited drugs in the BAL system could be defined from models of hepatic perfusion-elimination relationships. When the flow-limited drug administrated under a quasi-equilibrium condition, a two-compartment model for the concentration behavior of the drug was introduced and compared with a one-compartment model. For both models, equations involving hepatic drug clearance and various pharmacokinetic parameters were derived under initial bolus loading and constant-rate infusion plus bolus loading conditions. The concentration of enzyme-limited drug in the BAL decreased linearly with time in contrast with the concentration profile of the flow-limited drug followed by exponential functions. The perifusion model offers a quantitative understanding of the elimination kinetics of chemicals such as flow-limited and enzyme-limited drugs in a bioartificial liver and a comparison between the BAL and human liver.

The wound-healing effect of a glycoprotein fraction isolated from aloe vera

BACKGROUND

Aloe vera has been used as a family medicine for promoting wound healing, but it is not known which component of the plant is effective for this purpose.

OBJECTIVES

To isolate and characterize the component effective in wound healing.

METHODS

Chromatography, electrophoresis and spectroscopic methods were used. The cell-proliferation activity of each component isolated was measured by a [3H]thymidine uptake assay. The cell-proliferation activity of the effective component was tested on a three-dimensional raft culture (cell culture technique by which artificial epidermis is made from keratinocytes). The effect of the active component on cell migration and wound healing was observed on a monolayer of human keratinocytes and in hairless mice.

RESULTS

A glycoprotein fraction was isolated and named G1G1M1DI2. It showed a single band on sodium dodecyl sulphate-polyacrylamide gel electrophoresis, with an apparent molecular weight of about 5.5 kDa. It exhibited significant [3H]thymidine uptake in squamous cell carcinoma cells. The effect of G1G1M1DI2 on cell migration was confirmed by accelerated wound healing on a monolayer of human keratinocytes. When this fraction was tested on a raft culture, it stimulated the formation of epidermal tissue. Furthermore, proliferation markers (epidermal growth factor receptor, fibronectin receptor, fibronectin, keratin 5/14 and keratin 1/10) were markedly expressed at the immunohistochemical level. The glycoprotein fraction enhanced wound healing in hairless mice by day 8 after injury, with significant cell proliferation.

CONCLUSIONS

It is considered that this glycoprotein fraction is involved in the wound-healing effect of aloe vera via cell proliferation and migration.

Reconstruction of basement membrane in skin equivalent; role of laminin-1

To reconstruct the basement membrane in a skin equivalent, the epidermodermal interface was coated with porcine type IV collagen and mouse laminin-1 at various ratios before keratinocyte seeding. Laminin-1, a component of the basement membrane, induced massive infiltration of keratinocytes into the dermal equivalent, while type IV collagen induced discrete demarcation between dermal and epidermal compartments without any infiltrating cells. Immunohistochemical staining indicated that the laminin-induced infiltrating cells expressed endogenous type IV collagens at the cell periphery, which were not incorporated into the basement membrane structure. The infiltrating cells did not express fibronectin receptor alpha5beta1 integrin but showed MMP-9 secretion and cell surface associated MMP-2. However, when laminin-1 was preincubated with type IV collagen, laminin-1-induced keratinocyte infiltration as well as MMP-9 induction were almost completely suppressed to basal levels. Therefore, replenishment of the type IV collagen lattice seemed to cause laminin-stimulated cells to anchor to the lattice, in a similar manner to the basal cells on the basement membrane of normal skin. Our study suggests that the molar ratio of basement membrane components may determine the behavior of basal cells within the wound healing microenvironment, which is probably regulated either by extracellular matrix deposition or degradation.

Calcipotriol inhibits autocrine phosphorylation of EGF receptor in a calcium-dependent manner, a possible mechanism for its inhibition of cell proliferation and stimulation of cell differentiation

We report in this study that proliferation inhibition of SCC13 cells by calcipotriol was possibly mediated by its inhibitory effect on autocrine activation of EGF receptor. Based on MTT assay, PCNA staining, DAPI staining, and involucrin immunocytochemical staining, we showed that calcipotriol inhibited cell growth and stimulated differentiation but did not induce apoptosis. Western blot analysis of concanavalin-A-bound fraction demonstrated that calcipotriol specifically dephosphorylated 170- and 66-kDa polypeptides from 8 h posttreatment and complete dephosphorylation was observed at 12 h posttreatment. The 170- and 66-kDa polypeptides were confirmed as EGF receptor and Shc, respectively. Calcipotriol-mediated EGF receptor dephosphorylation required the presence of extracellular calcium. Similar kinetics of the dephosphorylation was also observed in HaCaT cells cultured in medium of high calcium concentration. By BrdU labeling, we also showed calcium dependency of calcipotriol for the inhibition of cell proliferation. Therefore, EGF receptor deactivation by calcipotriol might be a mechanism of action for the inhibition of cell proliferation and the stimulation of differentiation in SCC13 cell and HaCaT cells.

Reduced activity of topoisomerase II in an Adriamycin-resistant human stomach-adenocarcinoma cell line

A human stomach-adenocarcinoma cell line (MKN-45) was selected for resistance to Adriamycin by stepwise exposure to increasing concentrations of this agent. The resulting cell line (MKN/ADR) exhibited a high level of cross-resistance to topoisomerase II (topo II)-targeted drugs such as Adriamycin, mitoxantrone, and etoposide but showed no cross-resistance to other chemotherapeutic agents such as cisplatin, carboplatin, 5-fluorouracil, or mitomycin-C. P-glycoprotein encoded by the mdr-1 gene was not overexpressed in the MKN/ADR cell line. The doubling time of the MKN/ADR cell line (2.1 days) increased only slightly as compared with that of the MKN cell line (1.7 days). The patterns of cross-resistance to various chemotherapeutic agents led us to examine the cellular contents of topo II in both the drug-sensitive and the drug-resistant cells. Extractable topo II enzyme activity was 3-fold lower in MKN/ADR cells as compared with the parental MKN cells. Levels of topoisomerase I (topo I) catalytic activity were similar in both wild-type MKN and drug-resistant MKN/ADR cells. Southern-blot analysis of genomic DNA probed with topo IIalpha or IIbeta showed no sign of either gene rearrangement or hypermethylation. Northern-blot analysis revealed that both topo IIalpha and topo IIbeta mRNA transcripts were essentially identical in the MKN and MKN/ADR cells. In contrast, Western-blot analysis revealed an approximately 20-fold lower level of topo IIalpha in drug-resistant cells as compared with drug-sensitive cells, whereas topo IIbeta levels were similar in both lines. Moreover, the amount of in vivo topo IIalpha-DNA covalent complexes formed in the presence of etoposide was also approximately 20-fold lower in drug-resistant cells. No mutation was detected in the promoter region of the topo IIalpha gene in resistant cells as compared with sensitive cells. Thus, low levels of topo IIalpha polypeptide cannot be ascribed to changes in the mRNA levels. Collectively, the data suggest that a quantitative reduction in topo IIalpha may contribute to the resistance of MKN cells to Adriamycin and other topo II-targeted drugs.

Overexpression of tissue inhibitors of metalloproteinase-1 and -2 in the stroma of gastric cancer

The fundamental event of cancer invasion and metastasis is the complicated interaction of cancer cells with host cells, in which event, a number of proteases and their inhibitors are involved. Matrix metalloproteinases are the potent proteases in degrading the basement membrane and extra cellular matrix and are inhibited by specific endogeneous inhibitors, tissue inhibitors of metalloproteinases-1(TIMP-1) and TIMP-2. The expression of mRNA for TIMP-1 and -2 was investigated by Northern blot analysis in specimens taken from 27 patients with primary gastric adenocarcinoma; 25 samples from the primary site, six from the metastatic lymph nodes and two from the peritoneal fluids. The expression for TIMP-1 and -2 was compared in primary gastric cancer tissues, metastatic lymph nodes and normal gastric mucosae. TIMP-1 mRNA was overexpressed in 24 (96%) out of 25 primary cancer tissues compared with the paired normal mucosae, while TIMP-2 was in 10 (40%). In six specimens of metastatic lymph nodes, TIMP-1 and -2 were overexpressed in 6 (100%) and 4 (67%) specimens, respectively. Of two specimens prepared from the peritoneal fluids, all specimens overexpressed TIMP-1 compared with the those of primary cancer tissues, while one (50%) specimen overexpressed TIMP-2. Immunohistochemical staining was done to investigate the localization of TIMP-1 and -2, demonstrating that the immunoreactivity for TIMP-1 and -2 was clearly detected in the cytoplasm of the stromal cells. These results suggest that both TIMP-1 and -2 are overexpressed by stromal cells in most of primary and some metastatic gastric cancer tissues and that TIMP-1 and TIMP-2, produced by stromal cells, may play an important role in inhibiting the proteolytic activity of matrix metalloproteinases originated from cancer cells, in gastric cancer.

Biochemical characterization of cisplatin-resistance in MKN-45 human stomach adenocarcinoma cell line

We have established a cisplatin resistant subline, MKN/CDDP, from the MKN-45 human stomach adenocarcinoma cell line. MKN/CDDP was 10.7 fold more resistant to cisplatin, 5.4 fold resistant to carboplatin, 2.7 fold resistant to 5-fluorouracil and only 1.4 fold resistant to adriamycin. To investigate the mechanism of the cisplatin resistance in the MKN/CDDP subline, we performed the biochemical characterization of MKN-45 and MKN/CDDP. MKN/CDDP cells showed no induction in p-glycoprotein and topoisomerase II. The level of glutathione S-transferase-pi was higher in MKN/CDDP than the parent line, but a similar level of glutathione S-transferase-L isoform was observed. Superoxide dismutase activity was 1.67 fold higher in the MKN/CDDP subline than the parent line, but 60 kDa catalase was much lower in the MKN/CDDP subline. In addition to those changes. MKN/CDDP was not able to attach to the culture dish, which is probably due to the lack of fibronectin association on the cell surface. The MKN/CDDP subline revealed a variety of biochemical changes which are related to drug inactivation and to cell substratum adhesion. The significance of each modification in the development of the cisplatin resistance will be evaluated in future studies.

Expression of urokinase-type plasminogen activator, its receptor, and its inhibitor in gastric adenocarcinoma tissues

The plasminogen and plasmin system, which is mainly regulated by urokinase-type plasminogen activator (uPA), its receptor (uPAR) and its inhibitor (PAI-1), is generally believed to play a role in cancer invasion and metastasis. This study was conducted to investigate the role of uPA, uPAR and PAI-1 in the invasion and metastasis of gastric adenocarcinoma. The expression of mRNAs for uPA and PAI-1 was determined by Northern blot analysis in nine primary gastric cancer tissues, nine paired metastatic lymph nodes and normal gastric mucosa. The mRNA of uPA was not or faintly detected in normal mucosa, while the expression was increased in both primary gastric cancer tissues and metastatic lymph nodes to a similar degree. The mRNA expression for PAI-1 in the gastric cancer tissues was not different from that in the paired metastatic lymph nodes and normal mucosae. uPAR was determined by immunohistochemical staining, demonstrating that five (56%) and six (67%) out of nine primary gastric cancer tissues and nine paired metastatic lymph nodes were positive, respectively and the intensity was stronger in metastatic lymph nodes. The results support the concept that most gastric cancer cells may have an innately moderate level of uPA and uPAR, and that increase of uPAR expression can be considered to be closely associated with cancer invasion and metastasis.

Calcipotriol (MC 903), a synthetic derivative of vitamin D3 stimulates differentiation of squamous carcinoma cell line in the raft culture

We investigated whether calcipotriol, a synthetic derivative of vitamin D3 has the ability to correct defects in the control of proliferation and differentiation of human squamous carcinoma cells using the raft culture of SCC 13 cell line. Calcipotriol treatment at concentrations of 10(-8)-10(-6) M considerably enhanced terminal differentiation of SCC 13 cells, as shown by the appearance of enucleated-eosinophilic cells as well as granular cells in their upper cell layers. Immunohistochemical staining showed marked increases in the differentiation of marker proteins such as keratin 1, involucrin, or filaggrin expressing cells in their upper layers. The elevated expression at protein level was confirmed by immunoblotting analysis. Furthermore, calcipotriol also stimulated basal cell marker proteins such as keratin 14 and EGF receptor. However, the numbers of basal marker expressing cells within the architecture of SCC 13 raft culture were markedly reduced upon calcipotriol treatment, and their localization was mainly restricted in the innermost cell layer. In addition, calcipotriol stimulated EGF receptor biosynthesis for the first 16 hours post treatment and subsequently inhibited [3H]-thymidine incorporation of SCC 13 cells at 24 hours. In this study, we have clearly demonstrated that the long term application of calcipotriol considerably improves the complex defects in the regulation of proliferation and differentiation of SCC 13 cells, as supported by morphological and biochemical observations. This provides an evidence that calcipotriol can be applied clinically as a potent differentiation inducer in the treatment of human squamous cell carcinoma.

Mycobacterium tuberculosis infection in an orangutan (Pongo pygmaeus)

A respiratory disorder was noted in a 5-year-old female orangutan kept in the Yongin Farmland. Radiographically, multiple radiodense foci ranging from 2 to 6 mm diameter were seen throughout the lung lobes. Grossly, the thoracic cavity revealed a firm texture and grayish-pink discoloration of the left apical lung lobe. Histopathologically, multifocal areas of granulomatous pneumonia present the right and left apical lung lobes. Both primers from IS1081 and IS6110 targeting 196 bp and 245 bp respectively were used in polymerase chain reaction, Mycobacterium tuberculosis was isolated from liver and confirmed by polymerase chain reaction.

Peripheral blood lymphocyte subsets in patients with stomach cancer

The present study was conducted in order to investigate the immunologic alterations alongside the numerical changes in peripheral blood lymphocytes(PBL) and their subsets in stomach cancer patients. Lymphocyte surface markers were determined in 85 stomach cancer patients and 49 controls by indirect immunofluorescence technique using monoclonal antibodies. Monoclonal antibodies used were Leu 2a(CD8, suppressor/cytotoxic T cells), Leu 3a(CD4, inducer/helper T cells), Leu 4(CD3, pan T reagent), Leu 11(CD16, natural killer cells) and Leu 12(CD19, B cells). The numbers of PBL, CD3+, CD4+, CD8+, CD16+ and CD19+ cells significantly decreased and the CD4: CD8 value increased in 85 patients with stomach cancer compared to those in controls(p < 0.01). In stage I(n = 17), neither PBL, their subsets nor the CD4: CD8 value were significantly different from those of the controls. In stage II(n = 17), the numbers of PBL, CD3+, CD4+ and CD8+ cells decreased(p < 0.01). In stage III(n = 24) and IV(n = 27), PBL and all subsets measured decreased(p < 0.01). The CD4: CD8 value showed significant increases in stages III and IV(p < 0.01), because the CD8+ cells decreased to a greater extent than did the CD4+ cells. The results demonstrating that the lymphocyte subsets are depressed differentially with the stage suggest that host immunity is impaired with the progression of stomach cancer.

Lipid peroxidation and 8-hydroxydeoxyguanosine formation in rats fed fish oil with different levels of vitamin E

This study was conducted to investigate the protective role of vitamin E against the formations of lipid peroxides in plasma and tissues and of 8-hydroxydeoxyguanosine (8-OHdG) in livers of rats fed fish oil. Six-week-old male Sprague-Dawley rats were divided into four groups and fed experimental diets for 8 weeks. Three fish oil (F) groups were fed a menhaden fish oil and soybean oil (9:1) mixture as 10% (wt/wt) of their diet. These three groups (F0, FI, and FII) were provided with < or = 3, 45, and 209 IU of vitamin E/kg diet, respectively. The SI group was fed soybean oil with < or = 45 IU of vitamin E/kg diet. The F0 group had the highest levels of thiobarbituric acid-reactive substances (TBARS) in plasma (per milligram lipid), and liver, lung, heart, and kidney. The FI group had higher levels of TBARS than the SI group in plasma and tissues except the lung. In liver, the TBARS levels of the FII group were also higher than those of SI group, but in other tissues, similar levels were observed in the FII and SI groups. Plasma level of vitamin E was lowest in F0 group and vitamin E levels were generally lower in F groups than in SI group. These levels were expressed as vitamin E per milliliter of plasma. However, plasma E levels were similar when expressed per milligram plasma lipid. The liver 8-OHdG concentration tended to decrease as dietary vitamin E increased in the F groups, but there was no difference in the level of 8-OHdG between the FI and SI groups. These results suggest that vitamin E should be supplemented in fish oil feeding to prevent the enhanced lipid peroxidation and the formation of 8-OHdG in the body.

Chemical, in vitro, and in vivo evaluation of soybeans heat-treated by various processing methods

In trial 1, eight Holstein heifers weighing 410 kg were used in an 8 x 8 Latin square and fed TMR containing 79.3% alfalfa silage and 20% soybeans. The first four treatments were raw soybeans, soybeans roasted and held for 3 h at the roasting temperature, extruded soybeans, and soybeans roasted in a California Pellet Mill Jet-Sploder. The remaining four treatments were obtained by altering the residence time of soybeans in the Jet Sploder. The temperatures of soybeans exiting the roaster were 117, 126, 138, and 154 degrees C for the last four treatments. The soybeans held 3 h postroasting and the extruded soybeans resulted in the highest estimate of postruminal available lysine. Blood plasma concentrations of essential and branched-chain AA were highest in heifers fed soybeans held 3 h postroasting. In trial 2, 44 Holstein heifers weighing 150 to 250 kg were assigned randomly to one of four TMR. Diets consisted of 91.8% alfalfa silage and 7.5% of one of four soybean treatments. Treatments were raw soybeans, soybeans roasted in a drum roaster with an exit temperature of 146 degrees C, and those roasted with exit temperatures of 141 or 146 degrees C and held for .5 h. Estimated postruminal available lysine was higher for soybeans roasted and held versus roasted or raw soybeans. However, BW gain for heifers was similar across diets, averaging .90 kg/d for 12 wk. Concentrations of AA in plasma were not affected by diet. Overall, results support the recommendation of holding soybeans for at least .5 h following roasting.

Increased lipid transfer activities in hyperlipidemic rabbit plasma

Three models of hypercholesterolemia in rabbits were positively associated with plasma cholesteryl ester and triglyceride transfer activities. In cholesterol-fed rabbits, the transfer activities increased two- to three-fold when plasma cholesterol concentration reached about 1500 mg/dl. In hypercholesterolemia induced by feeding a cholesterol-free semisynthetic casein-sucrose diet, plasma cholesterol increased up to three-fold and the increase in cholesteryl ester and triglyceride transfer activities per unit of plasma cholesterol increment was similar to that in cholesterol-fed rabbits. Watanabe heritable hyperlipidemic rabbits, in which hypercholesterolemia is induced by a genetic defect of the LDL receptor, had significantly higher transfer activities than normolipidemic rabbits. However, fasting, which also induced hypercholesterolemia, lowered transfer activities, whereas refeeding returned them to prefasting levels. In rats, hypercholesterolemia induced by a high cholesterol diet did not increase cholesteryl ester and triglyceride transfer activities. Although hypercholesterolemia in rabbits may not be the primary cause of increased lipid transfer activities, some mechanism related to hypercholesterolemia appears to be associated with increased cholesteryl ester and triglyceride transfer activities.

Increased lipid transfer activities in hyperlipidemic rabbit plasma

Three models of hypercholesterolemia in rabbits were positively associated with plasma cholesteryl ester and triglyceride transfer activities. In cholesterol-fed rabbits, the transfer activities increased two- to three-fold when plasma cholesterol concentration reached about 1500 mg/dl. In hypercholesterolemia induced by feeding a cholesterol-free semisynthetic casein-sucrose diet, plasma cholesterol increased up to three-fold and the increase in cholesteryl ester and triglyceride transfer activities per unit of plasma cholesterol increment was similar to that in cholesterol-fed rabbits. Watanabe heritable hyperlipidemic rabbits, in which hypercholesterolemia is induced by a genetic defect of the LDL receptor, had significantly higher transfer activities than normolipidemic rabbits. However, fasting, which also induced hypercholesterolemia, lowered transfer activities, whereas refeeding returned them to prefasting levels. In rats, hypercholesterolemia induced by a high cholesterol diet did not increase cholesteryl ester and triglyceride transfer activities. Although hypercholesterolemia in rabbits may not be the primary cause of increased lipid transfer activities, some mechanism related to hypercholesterolemia appears to be associated with increased cholesteryl ester and triglyceride transfer activities.