Publications by authors named "Chimeglkham Banzrai"

9 Publications

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Portable HEPA filter air cleaner use during pregnancy and children's behavior problem scores: a secondary analysis of the UGAAR randomized controlled trial.

Environ Health 2021 07 5;20(1):78. Epub 2021 Jul 5.

Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada.

Background: Developmental exposure to particulate matter (PM) air pollution may impair children's behaviors. Our objectives were to quantify the impact of reducing indoor PM using portable HEPA filter air cleaners during pregnancy on behavioral problems in children and to assess associations between indoor fine PM (PM) concentrations during pregnancy and children's behavior.

Methods: This is a secondary analysis of a single-blind parallel-group randomized controlled trial in which we randomly assigned 540 non-smoking pregnant women to receive 1 or 2 HEPA filter air cleaners or no air cleaners. We administered the Behavior Assessment System for Children (BASC-3) to caregivers when children were a mean age of 23 months, and again at a mean age of 48 months. Primary outcomes were the four BASC-3 composite scales: externalizing problems, internalizing problems, adaptive skills, and the behavioral symptoms index. We imputed missing data using multiple imputation with chained equations. The primary analysis was by intention-to-treat. In a secondary analysis, we evaluated associations between BASC-3 composite indices and modeled trimester-specific PM concentrations inside residences.

Results: We enrolled participants at a median of 11 weeks gestation. After excluding miscarriages, still births and neonatal deaths, our analysis included 478 children (233 control and 245 intervention). We observed no differences in the mean BASC-3 scores between treatment groups. An interquartile increase (20.1 µg/m) in first trimester PM concentration was associated with higher externalizing problem scores (2.4 units, 95% CI: 0.7, 4.1), higher internalizing problem scores (2.4 units, 95% CI: 0.7, 4.0), lower adaptive skills scores (-1.5 units, 95% CI: -3.0, 0.0), and higher behavior symptoms index scores (2.3 units, 95% CI: 0.7, 3.9). Third trimester PM concentrations were also associated with some behavioral indices at age 4, but effect estimates were smaller. No significant associations were observed with PM concentrations during the second trimester or for any of the BASC indices when children were 2 years old.

Conclusion: We found no benefit of reducing indoor particulate air pollution during pregnancy on parent-reported behaviors in children. Associations between indoor PM concentrations in the first trimester and behavioral scores among 4-year old children suggest that it may be necessary to intervene early in pregnancy to protect children, but these exploratory findings should be interpreted cautiously.

Trial Registration: ClinicalTrials.gov: NCT01741051.
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http://dx.doi.org/10.1186/s12940-021-00763-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8258951PMC
July 2021

Portable HEPA filter air cleaner use during pregnancy and children's body mass index at two years of age: The UGAAR randomized controlled trial.

Environ Int 2021 11 2;156:106728. Epub 2021 Jul 2.

Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada. Electronic address:

Importance: Gestational exposure to particulate matter (PM) air pollution may increase the risk of childhood obesity, but the impact of reducing air pollution during pregnancy on obesity-related outcomes in childhood has not been examined.

Objective: To assess the impact of reducing gestational PM exposure on body mass index (BMI) at two years of age.

Methods: In this single-blind, parallel group randomized controlled trial in Ulaanbaatar Mongolia, we randomly assigned 540 pregnant women to receive 1-2 portable high efficiency particulate air (HEPA) filter air cleaners or no air cleaners. We measured height and weight when children were a mean age of 23.8 months. Our primary outcome was age- and sex-specific BMI z-score based on the World Health Organization 2007 Growth Charts. Secondary outcomes included age- and sex-specific weight z score, overweight/obesity (defined as BMI z-score > 2.00), and catch-up growth (defined using various cut-offs to identify children with relatively low birth weight for sex and gestational age and relatively high age- and sex-specific weight in childhood). We imputed missing outcome data using multiple imputation with chained equations and our primary analysis was by intention to treat (ITT). We estimated intervention effects on continuous and binary outcomes using linear and logistic regression, respectively.

Results: After excluding known miscarriages, still births, and neonatal deaths our analysis included 480 children (235 control and 245 intervention). The mean (SD) child BMI z score was 0.79 (1.0); 9.8% of children were overweight or obese. The mean BMI z score of children who were randomly assigned to the intervention group was 0.16-units lower (95% CI: -0.35, 0.04) than children in the control group. The intervention was also associated with reductions in overweight/obesity (odds ratio = 0.59; 95% CI: 0.31, 1.12). Catch-up growth occurred less frequently in the intervention group, but effect estimates varied depending on the specific definition of catch-up growth and confidence intervals consistently spanned no effect.

Conclusions: We found that the use of portable air cleaners during pregnancy was associated with improvements in obesity-related outcomes, although some effect estimates lacked precision. Reducing PM exposure during pregnancy may lead to improvements in cardiometabolic health in childhood.
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http://dx.doi.org/10.1016/j.envint.2021.106728DOI Listing
November 2021

Modification of multiple ion channel functions in vivo by pharmacological inhibition: observation by threshold tracking and modeling.

J Med Invest 2017 ;64(1.2):30-38

Department of Neurology, Tokushima University.

Maintenance of axonal excitability relies on complex balance by multiple ion currents, but its evaluation is limited by in vitro single channel neurophysiological study on overall behavior. We sought to evaluate behaviors of multiple ion currents by pharmacological blockade. The threshold tracking technique was used to measure multiple excitability indices on tail sensory nerve of normal male mice before and after administration of either BaCl or ivabradine. Mathematical modeling was used to identify the interval changes of the channel parameters. After administration of BaCl and ivabradine, the following changes were present: greater threshold changes of both depolarizing and hyperpolarizing threshold electrotonus by both; additionally, reduced S2 accommodation, reduced late subexcitability and increased superexcitability by BaCl, increased S3 accommodation by ivabradine. Mathematical modelling implied reduction of slow K conductance, along with reduction of H conductance (Ih) by BaCl; and reduction of Ih while augmentation of K conductances by ivabradine. Pharmacological blockade of a selective ion channel may be compensated by other ion channels. Unintended effects by ion channel modification could be caused by secondary current alteration by multiple ion channels. J. Med. Invest. 64: 30-38, February, 2017.
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http://dx.doi.org/10.2152/jmi.64.30DOI Listing
October 2017

Impaired Axonal Na(+) Current by Hindlimb Unloading: Implication for Disuse Neuromuscular Atrophy.

Front Physiol 2016 16;7:36. Epub 2016 Feb 16.

Department of Neurology, Tokushima University Tokushima, Japan.

This study aimed to characterize the excitability changes in peripheral motor axons caused by hindlimb unloading (HLU), which is a model of disuse neuromuscular atrophy. HLU was performed in normal 8-week-old male mice by fixing the proximal tail by a clip connected to the top of the animal's cage for 3 weeks. Axonal excitability studies were performed by stimulating the sciatic nerve at the ankle and recording the compound muscle action potential (CMAP) from the foot. The amplitudes of the motor responses of the unloading group were 51% of the control amplitudes [2.2 ± 1.3 mV (HLU) vs. 4.3 ± 1.2 mV (Control), P = 0.03]. Multiple axonal excitability analysis showed that the unloading group had a smaller strength-duration time constant (SDTC) and late subexcitability (recovery cycle) than the controls [0.075 ± 0.01 (HLU) vs. 0.12 ± 0.01 (Control), P < 0.01; 5.4 ± 1.0 (HLU) vs. 10.0 ± 1.3 % (Control), P = 0.01, respectively]. Three weeks after releasing from HLU, the SDTC became comparable to the control range. Using a modeling study, the observed differences in the waveforms could be explained by reduced persistent Na(+) currents along with parameters related to current leakage. Quantification of RNA of a SCA1A gene coding a voltage-gated Na(+) channel tended to be decreased in the sciatic nerve in HLU. The present study suggested that axonal ion currents are altered in vivo by HLU. It is still undetermined whether the dysfunctional axonal ion currents have any pathogenicity on neuromuscular atrophy or are the results of neural plasticity by atrophy.
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http://dx.doi.org/10.3389/fphys.2016.00036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4754663PMC
February 2016

Age-dependent effects on sensory axonal excitability in normal mice.

Neurosci Lett 2016 Jan 25;611:81-7. Epub 2015 Nov 25.

Department of Neurology, Tokushima University, Tokushima, Japan.

Serial recordings were performed to measure sensory excitability in peripheral nerves and elucidate age-dependent changes in neuronal ion currents in the peripheral sensory nervous system. The threshold tracking technique was used to measure multiple excitability indices in the tail sensory nerves of five normal male mice at four time points (6, 10, 14, and 19 weeks of age). A separate group of four mice was also measured at 43 weeks and at 60 weeks of age. Maturation was accompanied by an increase in early hyperpolarization and superexcitability at 10 weeks. At 60 weeks, the hyperpolarizing electrotonus shifted downward, while superexcitability became greater and subexcitability (double stimuli) decreased. Computer modeling showed that the most notable age-related interval changes in excitability parameters were Barrett-Barrett, H, and slow K(+) conductances. Understanding age-related changes in the excitability of sensory axons may provide a platform for understanding age-dependent sensory symptoms and developing age-specific channel-targeting therapies.
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http://dx.doi.org/10.1016/j.neulet.2015.11.032DOI Listing
January 2016

Upregulation of axonal HCN current by methylglyoxal: Potential association with diabetic polyneuropathy.

Clin Neurophysiol 2015 Nov 14;126(11):2226-32. Epub 2015 Mar 14.

Department of Neurology, Tokushima University, Tokushima, Japan.

Objective: To describe functional changes of axonal ion channels by a metabolic derivative of glucose, methylglyoxal (MGO), and its potential contribution to diabetic neuropathy.

Methods: (1) In wild-type male mice, multiple excitability measurements of sensory nerves were performed at baseline and 1week after serial administration of MGO (50mg/kg). (2) Excitability testing in patients with diabetic neuropathy (N=17) and healthy controls (N=12) were also conducted, and data were interpreted using mathematical modeling.

Results: In the animal study, there was a decrease in threshold changes by long hyperpolarization and in superexcitability after administration of MGO. In the preliminary human study, the threshold changes by long hyperpolarizing current were decreased in patients with diabetes. Mathematical modeling showed increased hyperpolarization-activated cation current (Ih) in the MGO-treated mice and in patients with diabetes.

Conclusion: Ih was upregulated after MGO administration in normal mice.

Significance: MGO is associated with abnormal axonal excitability. Hyperexcitability in diabetic polyneuropathy may, at least in part, be caused by dysfunctional axonal hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. A future study with a large sample size of the diabetic patients would clarify this hypothesis.
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http://dx.doi.org/10.1016/j.clinph.2015.02.058DOI Listing
November 2015

Effects of anesthetic agents on in vivo axonal HCN current in normal mice.

Clin Neurophysiol 2015 Oct 19;126(10):2033-9. Epub 2015 Jan 19.

Department of Neurology, Tokushima University, Tokushima, Japan.

Objective: The objective was to study the in vivo effects of anesthetic agents on peripheral nerve excitability.

Methods: Normal male mice were anesthetized by either isoflurane inhalation or a combination of medetomidine, midazolam, and butorphanol intraperitoneal injection ("triple agents"). Immediately after induction, the tail sensory nerve action potential was recorded and its excitability was monitored.

Results: Under both anesthetic protocols, there was an interval excitability change by long hyperpolarizing currents. There was greater threshold reduction approximately 30min post induction, in comparison to immediately post induction. Other excitability parameters were stable over time. Modeling suggested interval suppression of internodal H conductance or leak current.

Conclusions: Anesthetic agents affected responses to long hyperpolarizing currents.

Significance: Axonal excitability during intraoperative monitoring may be affected by anesthetic agents. Interpretation of interval excitability changes under anesthesia requires caution, especially with long hyperpolarizing currents.
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http://dx.doi.org/10.1016/j.clinph.2014.12.025DOI Listing
October 2015
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