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Objective: Expanded potential stem cells (EPSCs) are stem cells that can differentiate into embryonic and extraembryonic lineages, including extraembryonic endoderm and trophoblast lineages. Therefore, EPSCs have great potential in advancing regenerative medicine, elucidating disease mechanisms, and exploring early embryonic development. However, the generation and characterization of EPSCs in pigs have not been thoroughly explored. In this study, we successfully generated porcine EPSCs (pEPSCs)., Methods: We reprogrammed porcine fetal fibroblasts (PFFs) using an integration-free method with Sendai virus vectors., Results: The resulting pEPSCs expressed key pluripotency markers and demonstrated the ability to differentiate between embryonic and extraembryonic lineages. Notably, reprogramming into pEPSCs was associated with a transformation of mitochondrial morphology from the elongated form observed in PFFs to a globular shape, reflecting potential alterations in energy metabolism. We observed significant remodeling of mitochondrial morphology and a subsequent shift towards glycolytic energy dependence during the reprogramming of PFFs into pEPSCs., Conclusion: Our findings provide valuable insights into the characteristics of EPSCs in pigs and highlight their potential applications in regenerative medicine, disease modeling, and emerging fields such as cell-based meat production.

Cultured meat is a meat analogue produced by in vitro cell culture, which can replace the conventional animal production system. Tissue engineering using myogenic cells and biomaterials is a core technology for cultured meat production. In this study, we provide an efficient and economical method to produce skeletal muscle tissue-like structures by culturing chicken myoblasts in a fetal bovine serum (FBS)-free medium and plant-derived scaffolds. An FBS-free medium supplemented with 10% horse serum (HS) and 5% chick embryo extract (CEE) was suitable for the proliferation and differentiation of chicken myoblasts. Decellularized celery scaffolds (Decelery), manufactured using 1% sodium dodecyl sulfate (SDS), were nontoxic to cells and supported myoblast proliferation and differentiation. Decelery could support the 3D culture of chicken myoblasts, which could adhere and coagulate to the surface of the Decelery and form MYH1E + and F-actin + myotubes. After 2 weeks of culture on Decelery, fully grown myoblasts completely covered the surface of the scaffolds and formed fiber-like myotube structures. They further differentiated to form spontaneously contracting myofiber-like myotubes on the scaffold surface, indicating that the Decelery scaffold system could support the formation of a functional mature myofiber structure. In addition, as the spontaneously contracting myofibers did not detach from the surface of the Decelery, the Decelery system is a suitable biomaterial for the long-term culture and maintenance of the myofiber structures.

Mitochondria are crucial for cellular energy metabolism and are involved in signaling, aging, and cell death. They undergo dynamic changes through fusion and fission to adapt to different cellular states. In this study, we investigated the effect of knocking out the dynamin 1-like protein ( Dnm1l ) gene, a key regulator of mitochondrial fission, in neural stem cells (NSCs) differentiated from Dnm1l knockout embryonic stem cells ( Dnm1l -/- ESCs). Dnm1l -/- ESC-derived NSCs ( Dnm1l -/- NSCs) exhibited similar morphology and NSC marker expression (Sox2, Nestin, and Pax6) to brain-derived NSCs, but lower Nestin and Pax6 expression than both wild-type ESC-derived NSCs (WT-NSCs) and brain-derived NSCs. In addition, compared with WT-NSCs, Dnm1l -/- NSCs exhibited distinct mitochondrial morphology and function, contained more elongated mitochondria, showed reduced mitochondrial respiratory capacity, and showed a metabolic shift toward glycolysis for ATP production. Notably, Dnm1l -/- NSCs exhibited impaired self-renewal ability and accelerated cellular aging during prolonged culture, resulting in decreased proliferation and cell death. Furthermore, Dnm1l -/- NSCs showed elevated levels of inflammation and cell stress markers, suggesting a connection between Dnm1l deficiency and premature aging in NSCs. Therefore, the compromised self-renewal ability and accelerated cellular aging of Dnm1l -/- NSCs may be attributed to mitochondrial fission defects.

Background: Bradysia procera, a ginseng stem fungus gnat, is one of the most serious insect pests of Korean ginseng (Panax ginseng), causing significant damage to plant growth. The goal of this study was to determine the toxicity and mechanism of action of phenylpropanoids (trans-anethole and estragole) isolated from the methanol extract and hydrodistillate of Illicium verum fruit against third-instar larvae and eggs of Bradysia procera., Results: The filter-paper mortality bioassay revealed that estragole [median lethal concentration (LC 50 ) = 4.68 g/cm 2 ] has a significant fumigant effect, followed by trans-anethole (LC 50 = 43.92 g/cm 2 ). However, estragole had the lowest toxic effect when compared to commercially available insecticides. After 7 days, estragole and trans-anethole at 75 g/cm 2 inhibited egg hatchability up to 97% and 93%, respectively. At 0.09 g/cm 2 , insecticides had an inhibitory effect on egg-hatching ability ranging from 88% to 94%. Furthermore, in both closed and open containers, these active constituents were able to consistently induce vapor-phased toxicity. Both estragole and trans-anethole have the ability to inhibit acetylcholinesterase (AChE), which is involved in neurotransmitter function. However, the active constituent estragole from I. verum fruit acted as a potent AChE inhibitor and had a slightly lower effect on cyclic adenosine monophosphate (AMP) than octopamine alone., Conclusion: This finding suggests that estragole may influence Bradysia procera neurotransmitter function via both the AChE and octopaminergic receptors. More research is needed to demonstrate the potential applications of I. verum fruit-derived products as potential larvicides and ovicides for Bradysia procera population control. © 2022 Society of Chemical Industry., (© 2022 Society of Chemical Industry.)

Background and Objectives: DNA methyltransferases (Dnmts) play an important role in regulating DNA methylation during early developmental processes and cellular differentiation. In this study, we aimed to investigate the role of Dnmts in neural differentiation of embryonic stem cells (ESCs) and in maintenance of the resulting neural stem cells (NSCs)., Methods and Results: We used three types of Dnmt knockout (KO) ESCs, including Dnmt1 KO, Dnmt3a/3b double KO (Dnmt3 DKO), and Dnmt1/3a/3b triple KO (Dnmt TKO), to investigate the role of Dnmts in neural differentiation of ESCs. All three types of Dnmt KO ESCs could form neural rosette and differentiate into NSCs in vitro . Interestingly, however, after passage three, Dnmt KO ESC-derived NSCs could not maintain their self-renewal and differentiated into neurons and glial cells., Conclusions: Taken together, the data suggested that, although deficiency of Dnmts had no effect on the differentiation of ESCs into NSCs, the latter had defective maintenance, thereby indicating that Dnmts are crucial for self-renewal of NSCs.

As a novel cell type from eight-cell-stage embryos, extended pluripotent stem cells (EPSCs) are known for diverse differentiation potency in both extraembryonic and embryonic lineages, suggesting new possibilities as a developmental research model. Although various features of EPSCs have been defined, their ability to directly transfer extended pluripotency to differentiated somatic cells by cell fusion remains to be elucidated. Here, we derived EPSCs from eight-cell mouse embryos and confirmed their extended pluripotency at the molecular level and extraembryonic differentiation ability. Then, they were fused with OG2 +/- ROSA +/- neural stem cells (NSCs) by the polyethylene-glycol (PEG)-mediated method and further analyzed. The resulting fused hybrid cells exhibited pluripotential markers with upregulated EPSC-specific gene expression. Furthermore, the hybrid cells contributed to the extraembryonic and embryonic lineages in vivo and in vitro. RNA sequencing analysis confirmed that the hybrid cells showed distinct global expression patterns resembling EPSCs without parental expression of NSC markers, indicating the complete acquisition of extended pluripotency and the erasure of the somatic memory of NSCs. Furthermore, ultrastructural observation and metabolic analysis confirmed that the hybrid cells rearranged the mitochondrial morphology and bivalent metabolic profile to those of EPSCs. In conclusion, the extended pluripotency of EPSCs could be transferred to somatic cells through fusion-induced reprogramming.

Background: Cohesin is a chromosome-associated SMC-kleisin complex that mediates sister chromatid cohesion, recombination, and most chromosomal processes during mitosis and meiosis. However, it remains unclear whether meiosis-specific cohesin complexes are functionally active in mitotic chromosomes., Results: Through high-resolution 3D-structured illumination microscopy (3D-SIM) and functional analyses, we report multiple biological processes associated with the meiosis-specific cohesin components, α-kleisin REC8 and STAG3, and the distinct loss of function of meiotic cohesin during the cell cycle of embryonic stem cells (ESCs). First, we show that STAG3 is required for the efficient localization of REC8 to the nucleus by interacting with REC8. REC8-STAG3-containing cohesin regulates topological properties of chromosomes and maintains sister chromatid cohesion. Second, REC8-cohesin has additional sister chromatid cohesion roles in concert with mitotic RAD21-cohesin on ESC chromosomes. SIM imaging of REC8 and RAD21 co-staining revealed that the two types of α-kleisin subunits exhibited distinct loading patterns along ESC chromosomes. Third, knockdown of REC8 or RAD21-cohesin not only leads to higher rates of premature sister chromatid separation and delayed replication fork progression, which can cause proliferation and developmental defects, but also enhances chromosome compaction by hyperloading of retinoblastoma protein-condensin complexes from the prophase onward., Conclusions: Our findings indicate that the delicate balance between mitotic and meiotic cohesins may regulate ESC-specific chromosomal organization and the mitotic program., (© 2022. The Author(s).)

Background: Traditional teaching methods via faculty lectures and text-based materials lack interactivity. Hence, this research aimed to compare the effectiveness of story-based audiovisual mnemonics and the conventional text-reading method on medical students' memory consolidation., Methods: A single-center, systematically randomly sampled, single-blinded, controlled study was conducted among 80 first-year medical students. The students were randomly assigned to the text-reading (control) or story-based audiovisual mnemonics (intervention) group. After completing the learning session, the participants immediately took a test that consisted of ten multiple-choice questions, each of which had one correct single-response answer, and an oral recall test that consisted of ten keywords based on the given topics. The test was repeated at 1 week, 2 weeks, and 4 weeks post intervention. Descriptive and inferential statistics were utilized to assess the participants' responses. The mean score difference between the audiovisual mnemonics and control groups was determined by using a two-tailed unpaired t-test., Results: The participants in the intervention group had statistically significant higher marks in the multiple-choice test as compared to the participants in the control group. The intervention group also spent a statistically significant shorter time to recall keywords in the oral recall test in comparison to the control group., Conclusion: The story-based audiovisual mnemonics method is more effective than the conventional text-reading method in promoting memory retention among medical students., Competing Interests: Declaration of Competing Interests The authors declare that they have no competing interests., (Copyright © 2021 Southern Society for Clinical Investigation. Published by Elsevier Inc. All rights reserved.)

Assisted reproductive technologies (ARTs) have developed considerably in recent years; however, they cannot rectify germ cell aplasia, such as non-obstructive azoospermia (NOA) and oocyte maturation failure syndrome. In vitro gametogenesis is a promising technology to overcome infertility, particularly germ cell aplasia. Early germ cells, such as primordial germ cells, can be relatively easily derived from pluripotent stem cells (PSCs); however, further progression to post-meiotic germ cells usually requires a gonadal niche and signals from gonadal somatic cells. Here, we review the recent advances in in vitro male and female germ cell derivation from PSCs and discuss how this technique is used to understand the biological mechanism of gamete development and gain insight into its application in infertility.

Background: Phenological studies are a prerequisite for accomplishing higher productivity and better crop quality in cultivated plants. However, there are no phenological studies on Panax ginseng that improve its production yield. This study aims to redefine the phenological growth stages of P. ginseng based on the existing Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie (BBCH) scale and proposes a disease control reference., Methods: This study was conducted at the Korea Ginseng Corporation Experiment Station in Gyeonggi province, South Korea. Phenological observations were performed once weekly or twice monthly, based on the developmental stages. The existing BBCH scale with a three-digit code was used to redefine and update P. ginseng 's phenological growth codes., Results: The phenological description is divided into eight principal growth stages: three for vegetative growth (perennating bud, aerial shoot, and root development), four for reproductive growth (reproductive organ development, flowering, fruit development, and fruit maturation), and one for senescence according to the extended BBCH scale. A total of 58 secondary growth stages were described within the eight principal growth stages. Under each secondary growth stage, four mesostages are also taken into account, which contains the distinct patterns of the phenological characteristics in ginseng varieties and the process of transplanting seedlings. A practical management program for disease control was also proposed by using the BBCH code and the phenological data proposed in this work., Conclusion: The study introduces an extended BBCH scale for the phenological research of P. ginseng ., Competing Interests: All authors reported no conflict of interest., (© 2021 The Korean Society of Ginseng. Publishing services by Elsevier B.V.)

As the global population grows, we need a stable protein supply to meet the demands. Although plant-derived protein sources are widely available, animal meat maintains its popularity as a high-quality and savory protein source. Recently, cultured meat, also known as in vitro meat, has been suggested as a meat analog produced through in vitro cell culture technology. Cultured meat has several advantages over conventional meat, such as environmental protection, disease prevention, and animal welfare. However, cultured meat manufacturing is an emerging technology; thus, its further and dynamic development would be pivotal. Commercialization of cultured meat to the public will take a long time but cultured meat undoubtedly will come to our table someday. Here, we discuss the social and economic aspects of cultured meat production as well as the recent technical advances in cultured meat technology., Competing Interests: The authors declare no potential conflicts of interest., (© Korean Society for Food Science of Animal Resources.)

Medication is integral in treating alcohol use disorder. However, because of the small to medium effect size, much effort is being exerted to identify predicting factors for effective pharmacological treatment in alcohol abuse disorder. Rather than focusing on abstinence days, alcohol craving, or frequency of drinking, which has been the focus of previous studies. Recently, there have been several studies which focused on follow-up length as an indicator of pharmacological treatment effe ctiveness. The purpose of this study was to investigate the predicting factors of long-term follow-up in treating Korean alcoholics with naltrexone or acamprosate. A retrospective study was conducted. Medical records of all patients diagnosed from November 2008 to May 2017 with alcohol abuse or alcohol dependence at psychiatric clinics at PNUYH were reviewed. We examined total days of which naltrexone or acamprosate were prescribed, and investigated if there were predicting factors maintaining follow-up at least 180 days or more. With these data, logistic regression analysis was conducted. In naltrexone long group compared to naltrexone short group, factors of having medical comorbidities [odds ratio (OR) = 5.477, P = 0.012] showed higher OR. In acamprosate long group, factors of age (OR = 1.083, P = 0.030), and use of more than four psychotropic medications (OR = 7.107, P = 0.030), showed higher OR. In both medications, predicting factors were different from the other. Further study to investigate the reasons would provide us with a new insight.

The North Korean nuclear explosion test site in Punggye-ri is located in a seismically quiescent region on a stable Precambrian basement. The 3 September 2017 M W 5.6 North Korean underground nuclear explosion (UNE) test produced unprecedented strong ground motions. The peak ground accelerations might reach tens to hundreds m/s 2 on the surface of the UNE test site, decaying exponentially with distance. Ten shallow events with magnitudes greater than or equal to M L 2.5 and source depths less than 3 km followed the 2017 UNE for 5 months in an area with a radius of 15 km from the UNE where strong ground shaking was experienced. The largest event with M W 3.7 occurred 20 days after the 2017 UNE test at shallow depths less than 3 km. Its moment tensor solution indicates a combined source behavior with comparable strengths of double-couple and compensated linear vector dipole (CLVD) components, suggesting an unusual event different from typical natural earthquakes in the Korean Peninsula. The clustered shallow seismic events appeared to have occurred in damaged media that were effectively perturbed by the strong ground motions of the UNE.

Introduction: Identification of genetic variation is an essential ability for the long-term success of breeding programs and maximizes the use of germplasm resources. In East Asia, China has a long history of the cultivation of Perilla crop, but there has been little research on the genetic diversity and genetic relationships among accessions of Perilla crop and their weedy types., Objectives: To better understand the genetic variations of the cultivated and weedy types of Perilla crop in China, the 91 accessions were evaluated for genetic diversity by 21 simple sequence repeat (SSR) markers., Methods: SSR amplifications were conducted in a total volume of 20 µL, consisting of 20 ng genomic DNA, 1X PCR buffer, 0.5 µM forward and reverse primers, 0.2 mM dNTPs, and 1 U Taq polymerase. Power Marker version 3.25 was applied to obtain the information on the number of alleles, allele frequency, major allele frequency, gene diversity (GD), and polymorphic information content (PIC). The similarity matrix was used to construct an unweighted pair group method with arithmetic mean dendrogram by the application of SAHN-Clustering from NTSYS-pc.V.2.1., Results: A total of 147 alleles were identified with an average of 7 alleles per locus. The average values of PIC and GD were 0.577 and 0.537, respectively. The genetic diversity level of accessions from Northern China was lower than accessions from Southern China. The genetic diversity level and PIC values for accessions of var. crispa were the highest. For accessions of cultivated var. frutescens, genetic diversity in Southern China was higher than that in Northern China., Conclusion: Most cultivated Perilla accessions were clearly separated from weedy Perilla accessions, but there was no clear geographic structure between cultivated Perilla crop and weedy types based on their regional distribution. This study demonstrated the utility of SSR analysis for performing genetic and population analysis of cultivated and weedy types of Perilla accessions in China.

The distance-dependent coseismic and postseismic displacements produced by the 2011 M W 9.0 Tohoku-Oki megathrust earthquake caused medium weakening and stress perturbation in the crust around the Korean Peninsula, increasing the seismicity with successive M L 5-level earthquakes at the outskirts of high seismicity regions. The average M L 5-level occurrence rate prior to the megathrust earthquake was 0.15 yr -1 (0.05-0.35 yr -1 at a 95% confidence level), and the rate has increased to 0.71 yr -1 (0.23-1.67 yr -1 at a 95% confidence level) since the megathrust earthquake. The 2016 M L 5-level midcrustal earthquakes additionally changed the stress field in adjacent regions, inducing the 15 November 2017 M L 5.4 earthquake. The successive 2016 and 2017 moderate-size earthquakes built complex stress fields in the southeastern Korean Peninsula, increasing the seismic hazard risks in the regions of long-term stress accumulation. The increased seismic risks may continue until the medium properties and stress field are recovered.

Bradysia procera is a serious insect pest of Panax ginseng plants. This study was conducted to determine the toxicity and mechanism of action of three phenylpropanoids, three terpenoids, and a ketone from Syzygium aromaticum bud methanol extract and hydrodistillate against third-instar larvae and eggs of B. procera. In a filter-paper mortality bioassay, methyl salicylate (LC 50 , 5.26μg/cm 2 ) was the most toxic compound, followed by 2-nonanone, eugenol, and eugenyl acetate (8.77-15.40μg/cm 2 ). These compounds were significantly less toxic than either thiamethoxam, clothianidin, or cypermethrin. Egg hatching was inhibited by 97, 85, and 40% at 11.7μg/cm 2 of methyl salicylate, 2-nonanone, and eugenol, respectively. The egg-hatching inhibition of these insecticides was between 90 and 94% at 0.09μg/cm 2 . These constituents were consistently more toxic in closed versus open containers, indicating that toxicity was achieved mainly through the action of vapor. The mechanism of larvicidal action of methyl salicylate, eugenol, and eugenyl acetate might be primarily due to interference with the octopaminergic system. 2-Heptyl acetate and 2-nonanone might act on both acetylcholinesterase and the octopaminergic receptor. 2-Heptanone might act primarily on acetylcholinesterase. Further studies will warrant possible applications of S. aromaticum bud-derived products as potential larvicides and ovicides for the control of B. procera., (Copyright © 2018. Published by Elsevier Inc.)

In this study, 21 simple sequence repeat (SSR) markers were used to evaluate the genetic diversity and population structure among 77 Perilla accessions from high-latitude and middle-latitude areas of China. Ninety-five alleles were identified with an average of 4.52 alleles per locus. The average polymorphic information content (PIC) and genetic diversity values were 0.346 and 0.372, respectively. The level of genetic diversity and PIC value for cultivated accessions of Perilla frutescens var. frutescens from middle-latitude areas were higher than accessions from high-latitude areas. Based on the dendrogram of unweighted pair group method with arithmetic mean (UPGMA), all accessions were classified into four major groups with a genetic similarity of 46%. All accessions of the cultivated var. frutescens were discriminated from the cultivated P. frutescens var. crispa. Furthermore, most accessions of the cultivated var. frutescens collected in high-latitude and middle-latitude areas were distinguished depending on their geographical location. However, the geographical locations of several accessions of the cultivated var. frutescens have no relation with their positions in the UPGMA dendrogram and population structure. This result implies that the diffusion of accessions of the cultivated Perilla crop in the northern areas of China might be through multiple routes. On the population structure analysis, 77 Perilla accessions were divided into Group I, Group II, and an admixed group based on a membership probability threshold of 0.8. Finally, the findings in this study can provide useful theoretical knowledge for further study on the population structure and genetic diversity of Perilla and benefit for Perilla crop breeding and germplasm conservation.

In this study, eight inbred maize lines with high or low tolerance to cold temperature were investigated using bulk segregant analysis (BSA). Genetic diversity and genetic relationships were investigated using 100 simple sequence repeat (SSR) markers linked to cold tolerance in maize. A total of 319 alleles were identified. Among these, 128 were high coldtolerant-specific alleles and 61 were poorly coldtolerant-specific alleles, while the remaining 130 were shared between the two types. The number of alleles per locus ranged from 2 to 5, with an average of 3.19. The major allele frequency varied from 0.39 to 0.53 with an average of 0.47. The average gene diversity and polymorphic information content among all lines were 0.63 and 0.58, respectively. A dendrogram analysis identified three main clusters and most of the high tolerant inbred lines were clearly distinguished from the poorly tolerant inbred lines. In addition to the BSA, a total of 84 SSR markers were identified as high cold tolerance-specific alleles and 52 SSRs were detected as poorly cold tolerance-specific alleles. Of these, bnlg1273, umc1124, dupssr21, mmc0251, mmc0181, and phi041 have great potential for being molecular markers for cold tolerance in maize. Our results were in agreement with results previously reported for SSR markers linked with cold tolerance in maize. The identification and characterization of high and poorly cold tolerant maize lines based on SSR markers will be useful for future maize breeding studies.

Strong ground motions induce large dynamic stress changes that may disturb the magma chamber of a volcano, thus accelerating the volcanic activity. An underground nuclear explosion test near an active volcano constitutes a direct treat to the volcano. This study examined the dynamic stress changes of the magma chamber of Baekdusan (Changbaishan) that can be induced by hypothetical North Korean nuclear explosions. Seismic waveforms for hypothetical underground nuclear explosions at North Korean test site were calculated by using an empirical Green's function approach based on a source-spectral model of a nuclear explosion; such a technique is efficient for regions containing poorly constrained velocity structures. The peak ground motions around the volcano were estimated from empirical strong-motion attenuation curves. A hypothetical M7.0 North Korean underground nuclear explosion may produce peak ground accelerations of 0.1684 m/s(2) in the horizontal direction and 0.0917 m/s(2) in the vertical direction around the volcano, inducing peak dynamic stress change of 67 kPa on the volcano surface and ~120 kPa in the spherical magma chamber. North Korean underground nuclear explosions with magnitudes of 5.0-7.6 may induce overpressure in the magma chamber of several tens to hundreds of kilopascals.

Background and Objectives: Screen time among youth has been increasingly recognized as a public health problem because of its link with obesity. This has been demonstrated in many studies conducted in developed countries but few studies have addressed the problem in developing countries, despite an increase literature about the emergence of obesity and a greater access to screen devices in a country like Vietnam. Our study aimed at assessing screen time and its relationship with BMI in adolescents of Ho Chi Minh City (HCMC), Vietnam., Methods and Study Design: In a cross-sectional study of 2024 junior high school students aged 11-14 of HCMC, students were measured for BMI and questioned on time spent watching television/Video/DVD or using computer for fun. High users were defined as time >=2 h/d. International Obesity Task Force BMI cutoffs were used to define overweight and obesity., Results: Adolescents spent 2.2 h/d in screen time, with higher values for boys than girls (p<0.001). 53.8% of the respondents were high users. Time spent using computers for fun increased with age, and with the household wealthy index. The overall prevalence of overweight and obesity was 21.1%. Using multiple logistic regression, overweight and obesity was higher in boys (adjusted OR=2.66, 95% CI: [2.06; 3.44], p<0.001) and in children aged 11-12 who had a screen time >=2 h/d (adjusted OR=1.48, 95% CI: [1.09; 1.99], p<0.02)., Conclusions: In HCMC, a majority of adolescents spent >=2 h/d on screen time. High screen time is associated with an increased prevalence of overweight and obesity in young adolescents. Public health intervention programs are needed to reduce screen time among youth.

Nanostructured zinc oxide (ZnO) has received much attention due to its biological and medical applications, where detailed knowledge about particle sizing, aggregation propensity and its related hazards are crucial. Herein, the aggregation propensity and dissolution behavior of ZnO nanoparticles in aqueous medium (PBS) were studied as a function of concentration and further correlated with its toxicity in RAW 264.7 murine macrophages. Fast formation of smaller aggregates having high dissolution rate was observed at low concentration ZnO (LC-ZnO). Compared to high concentration ZnO (HC-ZnO) aggregates, the LC-ZnO aggregates were highly pronounced in terms of reactive oxygen species generation and exerting cell apoptosis, ascribed to the secondary size effect, size-dependent cellular uptake and ion solubility. This study outlines the nanoparticle concentration as a key factor in scaling its aggregation, dissolution tendency and also emphasizes the accounting of ingested nanomaterials long-term fate inside the cells., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Objective: The aim of this study was to examine changes over 5 years in body mass index (BMI) and waist circumference (WC) of adolescents from Ho Chi Minh City by age, gender and household economic status., Methods: Anthropometry including height, weight and WC measurements of 759 secondary high school students were collected 1-year apart in a prospective cohort study, between 2004 and 2009. BMI was calculated and overweight/obesity was defined using International Obesity Task Force (IOTF) BMI cutoffs. Abdominal 'overweight' and 'obesity' were defined as WC >91st-97th and 98th centile, respectively. BMI z-scores were also created., Results: Over the 5-year period, the absolute changes in mean BMI and WC were statistically significant (P<0.001). Boys had higher BMI and WC values than girls (P<0.001). The prevalence of overweight and obesity defined by IOTF BMI cutoff values increased gradually from 12.5% and 1.7% in the first year to 16.7% and 5.1% in the last year. Using WC cutoff values, the prevalence of abdominal overweight and obesity increased from 12.9% and 1.8% to 18.5% and 6.6%, respectively. BMI z-score curves shifted towards the right-hand side of the distribution (that is, towards overweight and obesity)., Conclusion: Overweight and obesity, as measured by BMI or WC, continued to increase among adolescents of Ho Chi Minh City over the 5-year period.

Nowadays, the exploration of zinc oxide nanoparticles (ZnO NPs) based products is booming in the various directions of bio-nanomedicine and other consumer products, but the comprehensive toxicological impact posed by ZnO NPs still remains unclear. The present study systematically investigates and correlates the toxicity evaluation of ZnO NPs in RAW 264.7 murine macrophages (in vitro) and male ICR mice (in vivo) by two different administration routes, i.e. g.i. and i.p. at different doses. The in vitro studies showed a slight rise in intracellular reactive oxygen species level (ROS), NF-κB transcription factor expression (TF) and NPs uptake at higher dose, indicating the non-toxic nature of ZnO NPs below 100 μg mL -1 doses. The in vivo results demonstrate a slight gain in body weight (BW), reduction in the organ weight, mild to severe pathological alteration in the organs depending upon NP dosage and mode of administration routes. The histopathological investigation suggests that the liver, kidney, lung, spleen, and pancreas may be the target organs for ZnO NPs according to the administration routes. Serum biochemistry assay shows an elevation in the GPT and ALP level, suggesting liver dysfunction. To our knowledge, this is the first study to report the toxic effects of ZnO NPs through i.p. administration. Further, the present work will offer a deeper understanding regarding the toxicology and in vivo behaviours of ZnO NPs in mice depending upon the various administration routes.

Background: Sedentary behavior is associated with increased risk of chronic disease and sedentary behavior is increasing among adolescents. Data on changes in sedentary behavior in developing countries are limited., Purpose: To describe 5-year longitudinal changes in nonschool sedentary hours among urban adolescents in Ho Chi Minh City, and to identify correlates with this change., Methods: This is a 5-year longitudinal cohort with systematic random sampling of 759 students from 18 junior high schools. All measures were taken annually between 2004 and 2009. Sedentary behavior was assessed by self-report and accelerometry. Generalized linear latent and mixed models were used to analyze the data in 2011., Results: Between 2004 and 2009, self-reported time spent in nonschool sedentary behavior increased from 498 to 603 minutes/day. In the 5th survey year, boys and girls (aged 16 years) were, respectively, 3.6 times (95% CI=2.3, 6.0) and 3.1 times (95% CI= 1.8, 5.0) more likely to spend ≥2 hours/day on screen time compared with baseline (aged 12 years). Accelerometer data adjusted for wearing time revealed that boys and girls aged 16 years had, respectively, 78 minutes/day (95% CI=48, 104) and 69 minutes/day (95% CI=34, 95) more nonschool sedentary time than those at the first accelerometer assessment (at age 13 years). Girls in the highest socioeconomic quartile spent an additional 90 minutes/day in sedentary behavior compared with girls in the lowest quartile (95% CI=52, 128)., Conclusions: Nonschool sedentary behavior increased among Vietnamese adolescents with age. The largest increase was in recreational screen time (28%), which would be the most obvious target for preventive health strategies., (Copyright © 2013 American Journal of Preventive Medicine. All rights reserved.)

Background: Two previous surveys conducted in Ho Chi Minh City revealed an increasing prevalence of overweight and obese adolescents, from 5.9% in 2002 to 11.7% in 2004. From 2004 to 2010, the government set up and implemented health promotion programs to promote physical activity and good nutritional habits in order to prevent overweight and obesity in children and adolescents. Our study aimed to estimate the prevalence of overweight and obesity among adolescents in urban areas of Ho Chi Minh City in 2010., Methods: A representative sample of 1,989 students aged 11-14 years was selected using a multistage cluster sampling method. 23 schools were randomly selected from the full list of all public junior high schools. In each selected school, 2 classes were chosen at random and all students from the class were examined. Age- and sex-adjusted overweight and obesity were defined using International Obesity Taskforce cut-offs., Results: The prevalences of overweight and obesity were 17.8% and 3.2%, respectively. Prevalences of overweight and obesity were significantly higher in boys (22%, 5.4% ) than in girls (13.3%, 1.3%, p<0.001) and higher in children from districts with a high economic level (20.5% , 3.8% ) than in those from districts with a low economic level (12.1%, 3.8%, p<0.001). Additionally, children living in wealthier families were more overweight and obese than those living in less wealthy families. When using WHO cutoffs, the overall prevalences of overweight and obesity reached 19.6% and 7.9%, respectively., Conclusion: Our study's findings suggest that the prevalence of overweight and obesity among secondary school students remains high, especially among boys living in wealthier families. Public health programs should therefore be developed or improved in order to promote good eating habits and physical activity among youth in HCMC.

Objective: This study aimed to describe the prevalence of metabolic syndrome (MetS) in adolescents of Ho Chi Minh City (HCMC) and to identify components of cardiovascular risk clusters., Methods: A cross-sectional study was conducted on a representative sample of 693 high-school students 13 to 16 years old in 2007. MetS was defined according to five different definitions: the Pediatric International Diabetes Federation, the Adult Treatment Panel III, and the modified definitions by Cook, Weiss, and De Ferranti. Principal components analysis (PCA) was carried out to cluster risk factors., Results: The prevalence of MetS was high and varied from 3.9% to 12.5%, depending on the criteria used. High levels of triglycerides (or low High Density Lipoprotein Cholesterol) and high blood pressure were the most prevalent components of MetS, while impaired glucose tolerance was the least prevalent. PCA showed three factors in boys (obesity, hypertension, dyslipidemia) that cumulatively explained 64.3%, and four factors in females (obesity, hypertension, dyslipidemia, and hyperglycemia) that accounted for 73.6% of the observed variance of MetS., Conclusions: The prevalence of MetS in HCMC adolescents was high. Obesity accounts for the maximum variance in clustering and appears to be a more powerful correlate of cardiovascular risk than other variables., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Objectives: The purpose of this study is to examine whether Hominis Placental pharmacopuncture solution (HPPS) combined with zinc-oxide nanoparticles (ZnO NP) activates RAW 264.7 cells., Methods: We soaked ZnO nanoparticles in the Hominis Placenta pharmacopuncture solution, thereby making a combined form (ZnO NP HPPS). The effect of ZnO NP HPPS on the intracellular reactive oxygen species (ROS) production was measured by 2', 7'-dichlorofluorescin diacetate (DCFH-DA) assay. The effect of ZnO NP HPPS on NF-κ B was measured by using a luciferase assay. The effect of ZnO NP HPPS on the cytokine expression was assessed by semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR). The cellular uptake of ZnO NP HPPS was measured by using a flow cytometric analysis, and cellular structural alterations were analyzed by using transmission electron microscopy (TEM)., Results: Neither the HPPS nor the ZnO NPs induced intracellular ROS production in RAW 264.7 cells. Neither of the materials activated NF-κ B or it's dependent genes, such as TNF-α, IL-1, and MCP-1. However, ZnO NP HPPS, the combined form of ZnO NPs and HPPS, did induce the intracellular ROS production, as well as prominently activating NF-κ B and it's dependent genes. Also, compared to ZnO NPs, it effectively increased the uptake by RAW 264.7 cells. In addition, cellular structural alterations were observed in groups treated with ZnO NP HPPS., Conclusions: Neither ZnO NP nor HPPS activated RAW 264.7 cells, which is likely due to a low cellular uptake. The ZnO NP HPPS, however, significantly activated NF-κ B and up-regulated its dependent genes such as TNF-α, IL-1, and MCP-1. ZnO NP HPPS was also more easily taken into the RAW 264.7 cells than either ZnO NP or HPPS.

Background: Accurate assessment of physical activity in adolescents at population level is necessary. In Vietnam, the International Physical Activity Questionnaire (IPAQ) and Physical Activity Questionnaire for Adolescents (PAQA) have been validated against accelerometers for use in adolescents. However, these questionnaires were originally designed for adults and showed poor validity. This study aims to assess the reliability and validity of the Vietnamese Adolescent Physical Activity Recall Questionnaire (V-APARQ)., Methods: One hundred and sixty five students were recruited from four junior high schools in Ho Chi Minh City Vietnam in 2004. V-APARQ asked students to report their usual organised and non-organised physical activity during a normal week and moderate- (MPA), vigorous- (VPA and moderate-to-vigorous- (MVPA) physical activity were calculated. Reliability was assessed by test-retest (2 weeks apart). Construct validity was assess by 7-day accelerometry, following the completion of the first V-APARQ., Results: The construct validity of the V-APARQ showed Spearman correlation of 0.25 and 0.22 for the assessment of the questionnaire when compared to the accelerometer. Test-retest reliability showed a weighted Kappa of 0.75 and the intra-class correlation coefficient for MVPA was 0.57 for the whole group (MPA =0.37 and VPA = 0.62), and were higher in boys than girls. The Bland-Altman plots for reliability show a mean difference of 0.4 minutes (95 % CI = -3.2, 4.0) for daily MVPA (n = 146) and the limits of agreement were -42.6 to 43.4 mins/day. In boys MVPA was lower on the first, compared with second administration of V-APARQ while the reverse was observed among girls., Conclusion: The reliability and validity of the V-APARQ were low to fair, but are comparable to other self-report physical activity questionnaires used among adolescents. V-APARQ will be useful for population monitoring of change in physical activity among urban Vietnamese adolescents.

Purpose: This study aimed to describe the 5-yr longitudinal change in moderate-to-vigorous physical activity (MVPA) among urban adolescents in Ho Chi Minh City, Vietnam, and to identify individual, family, and environmental factors associated with changes in MVPA., Methods: The Ho Chi Minh City Youth Cohort is a 5-yr longitudinal cohort with systematic random sampling of 759 students (48% boys) from 18 junior high schools in Ho Chi Minh City, conducted from 2004 to 2009. All measures were taken on five separate occassions. MVPA was assessed by self-report and accelerometry. Data were analyzed using multilevel linear regression models with estimation by generalized linear latent and mixed models., Results: Overall, after adjusting for covariates, students' accelerometer-based MVPA reduced 38% per annum (rate ratio = 0.62, 95% confidence interval (CI) = 0.59-0.64). Boys spent 2.9 times more in MVPA (rate ratio = 2.94, 95% CI = 2.63-3.22) than their female peers. Compared with normal-weight adolescents, overweight and obese adolescents were doing 40% (rate ratio = 0.60, 95% CI = 0.53, 0.67) less MVPA., Conclusions: MVPA significantly declined among Vietnamese adolescents with age. This finding is similar to those reported among Western adolescents and suggests that strategies to promote physical activity in adolescents are a priority in Vietnam because economic transitioning potentially increases the risk of adopting unhealthy lifestyle behaviors associated with obesity and chronic diseases.

Objectives: The Ho Chi Minh Youth cohort study aimed to assess the change in nutritional status; indicators of adiposity; diet; physical activity and sedentary behaviours; home, neighbourhood and school microenvironments and their complex relationships in adolescents in urban areas of Ho Chi Minh City., Design: Prospective 5-year cohort., Setting: Systematic random sampling was used to select 18 schools in urban districts., Participants: Children were followed up over 5 years with an assessment in each year. Consent, from both adolescents and their parents, was required. At baseline, 759 students were recruited into the cohort, and of these students, 740 remained in the cohort for the first round, 712 for the second round, 630 for the third round and 585 for the last round of follow-up., Primary and Secondary Outcome Measures: Anthropometric measurements were taken using established guidelines. Six main groups of exposure factors including dietary intake and behaviours, physical activity and sedentary behaviours, family social and physical environment, school environment, socioeconomic status and parental characteristics were measured., Results: Retention rate was high (77%). Within 5-year period, the prevalence of combined overweight and obesity using International Obesity Task Force cut-off values increased from 14.2% to 21.8%. Time spent on physical activity decreased significantly in the 5-year period from 87 to 50 min/day. Time spent on sedentary behaviours increased in the 5-year period from 512 to 600 min/day., Conclusions: The complete data analysis of this cohort study will allow a full exploration of the role of environmental and lifestyle behaviours on adolescent overweight and obesity and also identify the factors most strongly associated with excess weight gain and the appearance of overweight and obesity in different age groups of adolescents from this large city in Vietnam.

We developed a simple, versatile method of integrating hybrid thin films of reduced graphene oxide (RGO) nanosheets with multiwalled carbon nanotubes (MWNTs) via LbL assembly. This approach involves the electrostatic interactions of two oppositely charged suspensions of the RGO nanosheet with MWNTs. This method affords a hybrid multilayer of graphenes with excellent control over the optical and electrical properties. Moreover, the hybrid multilayer exhibits a significant increase of electronic conductivity after the thermal treatment, producing transparent and conducting thin films possessing a sheet resistance of 8 kOmega/sq with a transmittance of 81%. By taking advantage of the conducting network structure of MWNTs, which provides an additional flexibility and mechanical stability of RGO nanosheets, we demonstrate the potential application of hybrid graphene multilayer as a highly flexible and transparent electrode. Because of the highly versatile and tunable properties of LbL-assembled thin films, we anticipate that the general concept presented here offers a unique potential platform for integrating active carbon nanomaterials for advanced electronic, energy, and sensor applications.

Objective: The present study evaluates the reliability and validity of an FFQ designed for use with adolescents in urban Vietnam., Design: A cohort study was conducted between December 2003 and June 2004. The FFQ was administered three times over a 6-month period (FFQ 1-3) and nutrient intakes were compared to those obtained from four 24 h recalls collected over the same period (24 h recalls 1-4) using crude, energy-adjusted and de-attenuated correlation coefficients. The level of agreement between the two measurements was also evaluated with Bland-Altman analysis. The percentage of nutrient intakes classified within one quintile, as well as quadratic-weighted kappa statistics, were calculated., Setting: Ho Chi Minh City, Vietnam., Subjects: A total of 180 students were recruited in three junior high schools., Results: Coefficients ranged from 0.22 for retinol to 0.78 for fibre for short-term reliability, and from 0.30 for retinol to 0.81 for zinc for long-term reliability. Coefficients for nutrient intakes between the mean of the three FFQ and mean of four 24 h recalls were mostly around 0.40, but higher for energy-adjusted nutrients. After allowing for within-person variation, the mean coefficient was 0.52 for macronutrients and 0.46 for micronutrients. There were a relatively high proportion of nutrient intakes classified within one quintile and a small number grossly misclassified. Kappa values shows 'fair' to 'good' agreement for all food/nutrient categories, while the Bland-Altman plots indicated that the FFQ is accurate in assessing nutrient intake at a group level., Conclusions: This newly developed FFQ is a valid tool for measuring nutrient intake in adolescents in urban Vietnam.

A new method for determining chlorinity of water was developed in order to improve the old method by alleviating the environmental problems associated with the toxic chromate. The method utilizes a mediator, a weak acid that can form an insoluble salt with the titrant. The mediator triggers a sudden change in pH at an equivalence point in a titration. Thus, the equivalence point can be determined either potentiometrically (using a pH meter) or simply with an acid-base indicator. Three nontoxic mediators (phosphate, EDTA, and sulfite) were tested, and optimal conditions for the sharpest pH changes were sought. A combination of phosphate (a mediator) and phenolphthalein (an indicator) was found to be the most successful. The choices of the initial pH and the concentration of the mediator are critical in this approach. The optimum concentration of the mediator is ca. 1~2 mM, and the optimum value of the initial pH is ca. 9 for phosphate/phenolphthalein system. The method was applied to a sample of sea water, and the results are compared with those from the conventional Mohr-Knudsen method. The new method yielded chlorinity of a sample of sea water of (17.58 ± 0.22) g/kg, which is about 2.5% higher than the value (17.12 ± 0.22) g/kg from the old method.

Background/aims: Hepatoblastoma (HB) and hepatocellular carcinoma (HCC) are the two most common primary malignant liver tumours in children. Hepatic progenitor cells have been described and can be stained with K19, EpCAM and CD117. We investigated the morphology and staining patterns of primary liver tumours in Asian children., Methods: Four pathologists studied slides from 39 paediatric patients from Vietnam and Korea aged 8 months to 16 years. We performed immunohistochemical stains for K19, EpCAM and CD117, and polymerase chain reaction for tissue hepatitis B virus (HBV) DNA and hepatitis C virus (HCV) RNA., Results: There was agreement on the diagnosis of 24 cases of HCC and 10 cases of HB (one recurrent case). The diagnosis was split for six cases (HCC/HB). All 20 cases of HCC tested were HBV DNA+ and HCV RNA-. All nine cases of HB tested were HBV DNA-, while one was HCV RNA+. Of four HCC/HB cases tested, three were HBV DNA+ and all were HCV RNA-. By immunohistochemistry, 8/24 (33%) cases of HCC were K19+ and 18/24 (75%) were EpCAM+, 5/10 (50%) cases of HB were K19+ and 7/10 (70%) were EpCAM+ and 3/6 (50%) cases of HCC/HB were K19+ and 5/6 (83%) were EpCAM+. CD117 was negative in all 38 cases tested. Paediatric HCC has a morphology different from adult HCC, sometimes resembling HB, and a larger proportion of paediatric tumours have progenitor cell features., Conclusions: HB and HCC in children may represent malignant transformation at an early stage in the cellular lineage and often arise from hepatic progenitor cells.

Purposes: To identify factors associated with physical inactivity among adolescents in Ho Chi Minh City (HCMC)., Methods: A cross-sectional survey was conducted in 2004 among 2684 junior high school students using multistage cluster sampling. Time spent for physical and sedentary activities was collected with a validated questionnaire. Anthropometry, parental/family characteristics, neighborhood, and school environments were also measured. Level of activity was classified as physically active or inactive using standard criteria. Potential risk factors for physical inactivity were identified with hierarchical multivariate logistic regression, stratified by gender., Results: Physical inactivity was positively associated with child's overweight status (odds ratio [OR] = 2.5, 95% confidence interval [CI] = 1.9, 3.2), passive transportation (OR = 4.2, 95% CI = 3.3-5.2), not having recess exercises (OR = 1.3, 95% CI = 1.1-5.6), availability of a nearby game shop (OR = 1.8, 95% CI = 1.5-2.2), more time spent playing video games, watching television, and studying after class (OR = 2.3, 95% CI = 1.7-3.1; OR = 1.5, 95% CI = 1.2-1.9; and OR = 1.8, 95% CI = 1.3-2.4, respectively). The following factors decreased the odds of inactivity: schools having one to two sport meetings per year (OR = 0.7, 95% CI = 0.5-1.0), availability of a play yard (OR = 0.7, 95% CI = 0.6-0.9), older age group (OR = 0.2, 95% CI = 0.1-0.2), and male gender (OR = 0.6, 95% CI = 0.5-0.7). In boys, transportation, school sport meeting, availability of game shop near by, family's economic status, parental body mass index status, and time spent watching television were strongly associated with physical inactivity. In girls, time spent for study after class was one of the most important factors related to students' physical inactivity., Conclusions: Physical activity among adolescents in HCMC is related to household, school, and community factors. These factors and gender differences should be taken into account when promoting physical activity in adolescents.

Retinoic acids (RAs) modulate growth, differentiation, and apoptosis in normal, pre-malignant & malignant cells. In the present study, the effects of RA isomers (all-trans RA, 13-cis RA, and 9-cis RA) on the cell signal transduction of human breast cancer cells have been studied. The relationship between RAs and an enzymatic antioxidant system was also determined. Estrogen-receptor (ER) positive MCF-7 and ER-negative MDA-MB-231 human breast cancer cells were treated with different doses of each RA isomers, all-trans RA, 13-cis RA, or 9-cis RA. Treatment of RA isomers inhibited cell viability and induced apoptosis of MCF-7 cells as a result of increased caspase activity in cytoplasm and cytochrome C released from mitochondria. All-trans RA was the most effective RA isomer in both cell growth inhibition and induction of apoptosis in MCF-7 cells. However, no significant effect of RA isomers was observed on the cell growth or apoptosis in ER-negative MDA-MB-231 cells. In addition, activities of antioxidant enzymes such as catalase and glutathione peroxidase were decreased effectively after treatment of RA in MCF-7 cells, whereas SOD activity was rarely affected. Thus, the present data suggest that all-trans RA is the most potential inducer of apoptosis and modulator of antioxidant enzymes among RA isomers in MCF-7 human breast cancer cells.

Objective: To assess changes in the prevalence of overweight and obesity among adolescents in urban districts of Ho Chi Minh City between 2002 and 2004., Methods: Two surveys were conducted among high school students (11-16 years) in 2002 (n = 1003 students) and 2004 (n = 2684). International Obesity Taskforce (IOTF) sex and age specific BMI cut-offs were used to define overweight and obesity. Underweight was defined as a BMI-for-age z-score <-2, based on the US Centers for Disease Control and Prevention (CDC) 2000 growth reference. In 2002, students completed a questionnaire about household assets. In 2004, parents answered questions about their weight, height, education, occupation, and ownership of 14 household assets., Results: The prevalence of overweight and obesity increased from 5.0% and 0.6% in 2002, to 11.7% and 2.0% in 2004, respectively (p<0.001), while the prevalence of underweight decreased from 13.1% to 6.7%. There was a significant increase in prevalence of overweight and obesity by gender over the two years: the 113% increase in prevalence of overweight and obesity in boys was significantly greater than the 39% increase in girls (p<0.001). The percentage increase in overweight and obesity was considerably lower in adolescents from the poorest households (33%), than from the other quintiles of wealthier households (ranging from 77% to 124%) (p<0.001)., Conclusions: The prevalence of overweight and obesity among adolescents in Ho Chi Minh City is increasing rapidly. There is an urgent need to implement strategies for prevention and control amongst the adolescents of Ho Chi Minh City and other urban areas in Vietnam.

Hydrogen-ion selective solid contact electrodes based on tribenzylamine, dibenzylnaphthalenemethylamine, and dibenzylpyrenemethylamine ionophores were prepared. With these electrodes, we showed that the response ranges were influenced by the number of phenyl rings in the ionophores. The lower limits for a linear pH response in acidic solutions were pH 2.50, 0.65, and 0.50, respectively. As the number of phenyl rings in the ionophores increased, the slopes of the EMF responses of these electrodes did not change significantly, but their response extended toward an acidic range (shifted to pH 0.50). Thus, their dynamic response range became wider. A solid contact electrode with dibenzylpyrenemethylamine ionophore, in particular, showed the best selectivity, from the interference of cations and anions, and the best reproducibility of the EMF. This electrode was stored in Tris buffer solutions, artificial serum, and hydrofluoric acid solutions for one month without any loss of performance. Their response time was 8 s. Satisfactory results were obtained when it was tested directly with artificial serum (in pH range 6.0 - 8.5) and hydrofluoric acid.

To examine the use of health services for the treatment of childhood diarrhea in three southern provinces of Vietnam, and identified household, maternal, child and health service characteristics associated with this use, a cross-sectional household survey was conducted between November 1998 and January 1999. Women with a pre-school aged child living at home were the primary respondents for the survey questionnaires. Respondents were asked to recall diarrheal disease events experienced by their child during the two weeks prior to interview, and their responses to these events. Prevalence ratios (PR) were used to identify associations between maternal age, education, occupation, ethnicity, knowledge about diarrhea, feeding practises during diarrhea, household residence and economic status, disease severity, use of oral rehydration solution (ORS), time to nearest health care facility and overall satisfaction with local medical services, and the use of health care services for children ill with diarrhea. The two-week period prevalence of childhood diarrhea was 10% and varied by the province and ethnicity of the child's mother. Forty-three percent of mothers reported using ORS during diarrheal episodes. Seventy percent of mothers sought advice or treatment when their child became ill with diarrhea. After controlling for potential confounders in regression models, maternal ethnicity, maternal high school education (in comparison to no education or incomplete primary education), more severe disease and the use of ORS were factors associated with increased utilization of health care services. There was a low level of the utilization of ORS to treat children with diarrhea, especially by ethnic minority mothers. A high percentage of mothers reported low levels of satisfaction with medical services, especially those from ethnic minorities. Mothers from ethnic minorities and those with lower levels of education were less likely to seek advice or treatment. These findings suggest the need for programs to promote the use of ORS and use of appropriate services for the treatment of childhood diarrheal disease. Interventions are needed to improve the access of ethnic minority children to child health care services for the treatment of diarrhea.

We compared the slopes of the EMF responses and the response range of a solid contact electrode based on a tribenzylamine ionophore with those based on a tris(2-phenylethyl)amine ionophore and a tris(3-phenylpropyl)amine ionophore. Their slopes of the EMF responses showed, respectively, 57.7, 58.1, 59.0 mV pH(-1) (at 20 +/- 0.2 degrees C). Also, the linear pH response dynamic ranges were 2.74-10.63 for tribenzylamine-based SCEs, pH 4.47-12.59 for tris(2-phenylethyl)amine, and pH 4.60-13.24 for tris(3-phenylpropyl)amine. When the slopes of the EMF responses and the response range were considered, as the length of the replaced alkyl chain increased between the nitrogen atom and the phenyl group in the ionophore, though the dynamic range and the slopes of the EMF responses of these electrodes did not show any particularly different results, their response ranges moved toward the alkali range (shifted to pH 14). When it was directly applied to cow's milk (in pH range of 6.0-8.5), we could obtain the same satisfying results. This electrode continuously contacted a Tris 7.50 buffered solution as well as cow's milk for one month without any loss of performance. Also, especially, these electrodes showed very good results, such as stabilization of the base potential as well as the best reproducibility and response time (< 10 s).

A hydrogen ion-selective solid-contact electrode based on N,N,N',N'-tetrabenzylethanediamine has shown the best Nernstian slope and selectivity and the widest response range in a Tris buffered pH sample solution. Its linear dynamic range was pH 3.50-11.94, and the Nernstian slope showed 52.1 mV/pH (at 20 +/- 0.2 degrees C). When it was directly applied to human whole blood (in pH range 6.0-8.5) we could obtain the same satisfying results. This electrode continuously contacted a Tris 7.47 buffered solution, human whole blood and a hydrofluoric acid solution for one month without any loss of performance. Also, hydrofluoric acid did not influence the surface of this electrode, and thus it was maintained without showing any changes in potentials after being used in a hydrofluoric acid solution. The standard deviation in the determined e.m.f. differences was 1.5 mV (N = 5) for Tris buffer solutions of pH 6.5 and 1.1 mV at a Tris buffer solutions of pH 8.5. The 90% response time of the electrodes obtained by injecting of hydrochloric acid into the Tris buffer sample solution was less than 10 s. Especially, in the this paper, with these potential response characteristics of hydrogen ion selective poly(aniline) solid contact electrode, we have also presented the pH response mechanism of this electrode and the role of poly(aniline) and a doped anion in a poly(aniline) layer.

Hydrogen ion selective solid contact electrodes based on N,N'-dialkylbenzylethylenediamine (alkyl=butyl, hexyl, octy, decyl) are prepared. Solid contact electrodes and coated wire electrodes have been fabricated from polymer cocktail solutions based on N,N'-dialkylbenzylethylenediamine (alkyl=butyl, hexyl, octy, decyl). We showed that the response range and slopes are influenced by the alkyl chain length. Response ranges and Nernstian slops for solid contact electrodes were slightly better than for coated wire electrodes. Solid contact electrodes were shown linear selective to hydrogen ion in the pH ranges pH 4.5-13.0, 4.2-13.1, 3.4-13.0 and 3.0-13.2. and their Nernstian slopes were 49.7, 50.8, 51.5 and 53.7 mV pH(-1) at 20+/-0.2 degrees C, respectively. Stability is also improved especially when compared with coated wire electrodes. The 90% response time was <2 s and their electrical resistance varied in the range 2.37-2.76 MOmega. Especially solid contact electrodes with N,N'-didecylbenzylethylenediamine have shown the best selectivity and reproducibility of e.m.f..