Early Childhood Caries and Risk Factors in Vietnam.

OBJECTIVE: To investigate caries prevalence and examine its relationship with socioeconomic status and oral health behavior of Vietnamese kindergarten children. STUDY DESIGN: The study was carried out on 1,028 children aged 2-5 years in six kindergartens in Thua Thien Hue province, Vietnam. Information about socioeconomics and oral health behaviors was collected through a self-administered questionnaire, and oral health status by clinical dental examination. RESULTS: Clinical dental examination found that overall caries prevalence and mean dmft were 89.1% and 9.32. Caries prevalence and mean dmft increased greatly from two years to three years old, and gradually developed from three years to five years old. A logistic regression revealed that caries had an inverse relationship with mothers' educational level and a positive relationship with the habit of retaining food in the mouth for a long time in two-year-old children. Prolonged breastfeeding, more frequent sweets consumption, no thumb sucking habit, and higher modified debris index score were the risk factors for caries among three-to-five-year-old children. CONCLUSIONS: This study indicated a high prevalence of caries and related risk factors such as low mother's educational level and inappropriate oral health behavior among kindergarten children in Vietnam.

[Mechanisms of insulin resistance]. / Insuliiniresistenssin mekanismit.

Insulin resistance refers to an aberrant physiological response to insulin in its target tissues. Several signal transduction mechanisms sensing intracellular stress are activated in situations where energy supply exceeds the cells' energy requirements. This stress interferes with insulin-induced intracellular signal transduction and leads to an inflammatory state. The activation of inflammatory responses in peripheral tissues and central nervous system weakens the body's insulin sensitivity, glucose tolerance and predisposes to obesity. Insulin resistance is thus a crucial metabolic disorder in obesity, type 2 diabetes and cardiovascular diseases.

High Prevalence of Post-Traumatic Stress Disorder and Psychological Distress Among Healthcare Workers in COVID-19 Field Hospitals: A Cross-Sectional Study from Vietnam.

Objective: To evaluate the prevalence of post-traumatic stress disorder (PTSD) and other psychological disturbances in the Vietnamese healthcare workers (HCWs) at COVID-19 field hospitals. Methods: A cross-sectional study was conducted using the Impact of Event Scale-Revised (IES-R) to measure PTSD and the Depression Anxiety Stress scale (DASS) to measure other psychological disturbances. The anxiety about COVID-19 was evaluated by the fear of COVID-19 (FOC) scale. A self-developed questionnaire was used to assess work conditions and HCW's major concerns and preparedness. Ordinal logistic regression was used to identify factors associated with the severity of PTSD. A structural modeling equation (SEM) model was fitted to examine the correlation between PTSD and other psychological disturbances. Results: A total of 542 HCWs participated in this study. The prevalence of PTSD was 21.2%, most cases were mild. In the ordinal logistic regression analysis, a history of mental illness, poor preparedness, working in a condition with poor resources, a greater number of concerns, and greater fear of COVID-19 were independently associated with higher severity of PTSD. The prevalence of depression, anxiety, and stress was 46.8%, 38.3%, and 60.2, respectively. In the SEM model, PTSD and psychological disturbances had a strong correlation (standardized covariance 0.86). Conclusion: The prevalence of PTSD and other psychological disturbances was alarmingly high among HCWs who worked at COVID-19 field hospitals. The reported associated factors can be useful for policymakers and health authorities in the preparation for future pandemics.

Structural and enzyme activity studies demonstrate that aryl substituted 2,3-butadienamine analogs inactivate Arthrobacter globiformis amine oxidase (AGAO) by chemical derivatization of the 2,4,5-trihydroxyphenylalanine quinone (TPQ) cofactor.

Copper amine oxidases (CAOs) are a family of redox active enzymes containing a 2,4,5-trihydroxyphenylalanine quinone (TPQ) cofactor generated from post translational modification of an active site tyrosine residue. The Arthrobacter globiformis amine oxidase (AGAO) has been widely used as a model to guide the design and development of selective inhibitors of CAOs. In this study, two aryl 2,3-butadienamine analogs, racemic 5-phenoxy-2,3-pentadienylamine (POPDA) and racemic 6-phenyl-2,3-hexadienylamine (PHDA), were synthesized and evaluated as mechanism-based inactivators of AGAO. Crystal structures show that both compounds form a covalent adduct with the amino group of the substrate-reduced TPQ, and that the chemical structures of the rac-PHDA and rac-POPDA modified TPQ differ by the allenic carbon that is attached to the cofactor. A chemical mechanism accounting for the formation of the respective TPQ derivative is proposed. Under steady-state conditions, no recovery of enzyme activity is detected when AGAO pre-treated with rac-PHDA or rac-POPDA is diluted with excess amount of the benzylamine substrate (100-fold K(m)). Comparing the IC(50) values further reveals that the phenoxy substituent in POPDA offers an approximately 4-fold increase in inhibition potency, which can be attributed to a favourable binding interaction between the oxygen atom in the phenoxy group and the active site of AGAO as revealed by crystallographic studies. This hypothesis is corroborated by the observed >3-fold higher partition ratio of PHDA compared to POPDA. Taken together, the results presented in this study reveal the mechanism by which aryl 2,3-butadienamines act as mechanism-based inhibitors of AGAO, and the potency of enzyme inactivation could be fine-tuned by optimizing binding interaction between the aryl substituent and the enzyme active site.

Impact of School-Based Oral Health Education on Vietnamese Adolescents: A 6-Month Study.

We have evaluated the impact of a school-based intervention on oral health knowledge, behaviours, and oral health status of adolescents in Vietnam. This 6-month study included 462 adolescents aged 12 years from four selected schools in Hue City, Vietnam. The intervention group received a 15-min lecture by a dentist and hands-on session on mouth observation and toothbrushing skills. The control group did not engage in any educational activities during the follow-up period. Data were collected at baseline and 6 months through a survey questionnaire and clinical examination. The Debris Index was used for dental plaque; the Papillary, Marginal, Attached gingiva index for gingivitis; and the Decayed, Missing, and Filled Teeth index (World Health Organization modification) for dental caries. Difference-in-difference analysis was used to compare changes between the groups. After 6 months, the control tended to show decreased toothbrushing frequency and increased dental plaque accumulation. The participants in the intervention group showed improved oral health knowledge (p < 0.01), behavior (p < 0.05), and hygiene (p < 0.001) compared to the control group. However, the intervention did not improve dental caries and gingivitis. A single school-based oral health education program can help adolescents improve oral health knowledge and prevent the deterioration of short-term oral health behavior and hygiene.

Identifying Developmental Language Disorder in Vietnamese Children.

Purpose Developmental language disorder (DLD), defined by low language performance despite otherwise normal development, can negatively impact children's social and academic outcomes. This study is the 1st to examine DLD in Vietnamese. To lay the foundation, we identified cases of DLD in Vietnam and explored language-specific characteristics of the disorder. Method Teacher ratings of 1,250 kindergarteners living in Hanoi, Vietnam, were used to recruit children with and without risk for DLD. One hundred four children completed direct measures of vocabulary and language sampling, and their parents completed in-depth surveys. We examined convergence and divergence across tasks to identify measures that could serve as reliable indicators of risk. Then, we compared performance on direct language measures across ability levels. Results There were positive associations between teacher and parent report and between report and direct language measures. Three groups were identified based on convergence across measures: DLD, some risk for DLD, and no risk. The DLD group performed lowest on measures of receptive and expressive vocabulary, mean length of utterance, and grammaticality. Although children with DLD exhibited a greater number of errors, the types of errors found were similar across DLD and No Risk groups. Conclusions Similar to rates found globally, 7% of the kindergarten population in Vietnam exhibited risk for DLD. Results highlight the importance of parent and teacher report and the value of multiple measures to identify DLD. We discuss potential clinical markers for DLD in the Vietnamese language and outline future directions.

TRP-independent inhibition of the phospholipase C pathway by natural sensory ligands.

Menthol, cinnamaldehyde, and camphor are activators for temperature-sensitive transient receptor potential ion channels (thermoTRPs). Here we found that these three compounds inhibit the phospholipase C (PLC) signaling. P2Y purinoceptor-mediated or histamine receptor-mediated cytosolic calcium mobilization through the PLC pathway was significantly suppressed by menthol, cinnamaldehyde, and camphor. Experiments using a fluorescent pleckstrin homology domain of PLCdelta1 and IP1 accumulation assays demonstrated that direct inhibition of PLC activity occurred upon the addition of the sensory compounds. P2Y receptor-mediated PLC activation is part of the mechanism of platelet aggregation. The three compounds inhibited ADP-induced platelet aggregation. Calcium influx studies showed that thermoTRPs do not function in platelets, suggesting that the anti-aggregation effect is independent of thermoTRP activity. These results suggest that menthol, cinnamaldehyde, and camphor are able to modify PLC signaling and that those effects may lead to changes in cellular functions. This study also identifies new types of compounds that could potentially modulate platelet-related pathological events.

Probing heme coordination states of inducible nitric oxide synthase with a ReI(imidazole-alkyl-nitroarginine) sensitizer-wire.

Mammalian inducible nitric oxide synthase (iNOS) catalyzes the production of l-citrulline and nitric oxide (NO) from L-arginine and O2. The Soret peak in the spectrum of the iNOS heme domain (iNOSoxy) shifts from 423 to 390 nm upon addition of a sensitizer-wire, [ReI-imidazole-(CH2)8-nitroarginine]+, or [ReC8argNO2]+, owing to partial displacement of the water ligand in the active site. From analysis of competitive binding experiments with imidazole, the dissociation constant (Kd) for [ReC8argNO2]+-iNOSoxy was determined to be 3.0+/-0.1 microM, confirming that the sensitizer-wire binds with higher affinity than both L-arginine (Kd=22+/-5 microM) and imidazole (Kd=14+/-3 microM). Laser excitation (355 nm) of [ReC8argNO2]+-iNOSoxy triggers electron transfer to the active site of the enzyme, producing a ferroheme in less than approximately 1 micros.

The transcription factor Prox1 is essential for satellite cell differentiation and muscle fibre-type regulation.

The remarkable adaptive and regenerative capacity of skeletal muscle is regulated by several transcription factors and pathways. Here we show that the transcription factor Prox1 is an important regulator of myoblast differentiation and of slow muscle fibre type. In both rodent and human skeletal muscles Prox1 is specifically expressed in slow muscle fibres and in muscle stem cells called satellite cells. Prox1 activates the NFAT signalling pathway and is necessary and sufficient for the maintenance of the gene program of slow muscle fibre type. Using lineage-tracing we show that Prox1-positive satellite cells differentiate into muscle fibres. Furthermore, we provide evidence that Prox1 is a critical transcription factor for the differentiation of myoblasts via bi-directional crosstalk with Notch1. These results identify Prox1 as an essential transcription factor that regulates skeletal muscle phenotype and myoblast differentiation by interacting with the NFAT and Notch pathways.

CD40 Co-stimulation Inhibits Sustained BCR-induced Ca Signaling in Response to Long-term Antigenic Stimulation of Immature B Cells.

Regulation of B cell receptor (BCR)-induced Ca(2+) signaling by CD40 co-stimulation was compared in long-term BCR-stimulated immature (WEHI-231) and mature (Bal-17) B cells. In response to long-term pre-stimulation of immature WEHI-231 cells to α-IgM antibody (0.5~48 hr), the initial transient decrease in BCR-induced [Ca(2+)](i) was followed by spontaneous recovery to control level within 24 hr. The recovery of Ca(2+) signaling in WEHI-231 cells was not due to restoration of internalized receptor but instead to an increase in the levels of PLCγ2 and IP(3)R-3. CD40 co-stimulation of WEHI-231 cells prevented BCR-induced cell cycle arrest and apoptosis, and it strongly inhibited the recovery of BCR-induced Ca(2+) signaling. CD40 co-stimulation also enhanced BCR internalization and reduced expression of PLCγ2 and IP(3)R-3. Pre-treatment of WEHI-231 cells with the antioxidant N-acetyl-L-cysteine (NAC) strongly inhibited CD40-mediated prevention of the recovery of Ca(2+) signaling. In contrast to immature WEHI-231 cells, identical long-term α-IgM pre-stimulation of mature Bal-17 cells abolished the increase in BCR-induced [Ca(2+)](i), regardless of CD40 co-stimulation. These results suggest that CD40-mediated signaling prevents antigen-induced cell cycle arrest and apoptosis of immature B cells through inhibition of sustained BCR-induced Ca(2+) signaling.

Facilitation of Ca2+-activated K+ channels (IKCa1) by mibefradil in B lymphocytes.

K+ channels play critical roles in the proliferation and activation of lymphocytes. Mouse B cells express large-conductance background K+ channel (LK bg) in addition to the voltage-gated K+ channel (Kv) and Ca2+-activated K+ channel current (IKCa1). Mibefradil, a blocker of T-type Ca2+ channels, has been reported to affect the proliferation of immune cells. In this study, we investigated the effects of mibefradil on the membrane potential and ion channels in murine B cell lines, WEHI-231 and Bal-17. In the whole-cell patch clamp experiments, mibefradil blocked Kv and LK bg current with half inhibitory concentration (IC50), 1.9 and 2.3 microM, respectively. Interestingly, IKCa1 current was increased by mibefradil. In the inside-out patch clamp study with cloned murine IKCa1 (mIKCa1) in HEK-293, mibefradil increased both Ca2+ sensitivity and maximum activity of mIKCa1. At high concentrations (>10 microM), mibefradil inhibited mIKCa1 in a voltage-dependent manner. Application of anti-IgM antibody to stimulate B cell receptors (BCR-ligation) induced transient hyperpolarization of Bal-17 and WEHI-231 cells, which became persistent with 1 microM mibefradil. The hyperpolarizing response was abolished by charybdotoxin, a selective blocker for SK4/IKCa1. In summary, our study firstly reports the ion channel-activating effects of mibefradil. The selective potent activation of IKCa1 suggests that mibefradil-derived drugs might be useful in the control of cell responses related with IKCa1.

Loss of autophagy diminishes pancreatic beta cell mass and function with resultant hyperglycemia.

Autophagy is a cellular degradation-recycling system for aggregated proteins and damaged organelles. Although dysregulated autophagy is implicated in various diseases including neurodegeneration, its role in pancreatic beta cells and glucose homeostasis has not been described. We produced mice with beta cell-specific deletion of Atg7 (autophagy-related 7). Atg7 mutant mice showed impaired glucose tolerance and decreased serum insulin level. beta cell mass and pancreatic insulin content were reduced because of increased apoptosis and decreased proliferation of beta cells. Physiological studies showed reduced basal and glucose-stimulated insulin secretion and impaired glucose-induced cytosolic Ca2+ transients in autophagy-deficient beta cells. Morphologic analysis revealed accumulation of ubiquitinated protein aggregates colocalized with p62, which was accompanied by mitochondrial swelling, endoplasmic reticulum distension, and vacuolar changes in beta cells. These results suggest that autophagy is necessary to maintain structure, mass and function of pancreatic beta cells, and its impairment causes insulin deficiency and hyperglycemia because of abnormal turnover and function of cellular organelles.

Mechanosensitive activation of K+ channel via phospholipase C-induced depletion of phosphatidylinositol 4,5-bisphosphate in B lymphocytes.

In various types of cells mechanical stimulation of the plasma membrane activates phospholipase C (PLC). However, the regulation of ion channels via mechanosensitive degradation of phosphatidylinositol 4,5-bisphosphate (PIP(2)) is not known yet. The mouse B cells express large conductance background K(+) channels (LK(bg)) that are inhibited by PIP(2). In inside-out patch clamp studies, the application of MgATP (1 mm) also inhibited LK(bg) due to the generation of PIP(2) by phosphoinositide (PI)-kinases. In the presence of MgATP, membrane stretch induced by negative pipette pressure activated LK(bg), which was antagonized by PIP(2) (> 1 microm) or higher concentration of MgATP (5 mm). The inhibition by PIP(2) was partially reversible. However, the application of methyl-beta-cyclodextrin, a cholesterol scavenger disrupting lipid rafts, induced the full recovery of LK(bg) activity and facilitated the activation by stretch. In cell-attached patches, LK(bg) were activated by hypotonic swelling of B cells as well as by negative pressure. The mechano-activation of LK(bg) was blocked by U73122, a PLC inhibitor. Neither actin depolymerization nor the inhibition of lipid phosphatase blocked the mechanical effects. Direct stimulation of PLC by m-3M3FBS or by cross-linking IgM-type B cell receptors activated LK(bg). Western blot analysis and confocal microscopy showed that the hypotonic swelling of WEHI-231 induces tyrosine phosphorylation of PLCgamma2 and PIP(2) hydrolysis of plasma membrane. The time dependence of PIP(2) hydrolysis and LK(bg) activation were similar. The presence of LK(bg) and their stretch sensitivity were also proven in fresh isolated mice splenic B cells. From the above results, we propose a novel mechanism of stretch-dependent ion channel activation, namely, that the degradation of PIP(2) caused by stretch-activated PLC releases LK(bg) from the tonic inhibition by PIP(2).

Picosecond photoreduction of inducible nitric oxide synthase by rhenium(I)-diimine wires.

In a continuing effort to unravel mechanistic questions associated with metalloenzymes, we are developing methods for rapid delivery of electrons to deeply buried active sites. Herein, we report picosecond reduction of the heme active site of inducible nitric oxide synthase bound to a series of rhenium-diimine electron-tunneling wires, [Re(CO)3LL']+, where L is 4,7-dimethylphenanthroline and L' is a perfluorinated biphenyl bridge connecting a rhenium-ligated imidazole or aminopropylimidazole to a distal imidazole (F8bp-im (1) and C3-F8bp-im (2)) or F (F9bp (3) and C3-F9bp (4)). All four wires bind tightly (Kd in the micromolar to nanomolar range) to the tetrahydrobiopterin-free oxidase domain of inducible nitric oxide synthase (iNOSoxy). The two fluorine-terminated wires displace water from the active site, and the two imidazole-terminated wires ligate the heme iron. Upon 355-nm excitation of iNOSoxy conjugates with 1 and 2, the active site Fe(III) is reduced to Fe(II) within 300 ps, almost 10 orders of magnitude faster than the naturally occurring reduction.

Redox couples of inducible nitric oxide synthase.

We report direct electrochemistry of the iNOS heme domain in a DDAB film on the surface of a basal plane graphite electrode. Cyclic voltammetry reveals FeIII/II and FeII/I couples at -191 and -1049 mV (vs Ag/AgCl). Imidazole and carbon monoxide in solution shift the FeIII/II potential by +20 and +62 mV, while the addition of dioxygen results in large catalytic waves at the onset of FeIII reduction. Voltammetry at higher scan rates (with pH variations) reveals that the FeIII/II cathodic peak can be resolved into two components, which are attributable to FeIII/II couples of five- and six-coordinate hemes. Digital simulation of our experimental data implicates water dissociation from the heme as a gating mechanism for ET in iNOS.