Dengue infection in children in Ratchaburi, Thailand: a cohort study. II. Clinical manifestations

Background

Dengue infection is one of the most important mosquito-borne diseases. More data regarding the disease burden and the prevalence of each clinical spectrum among symptomatic infections and the clinical manifestations are needed. This study aims to describe the incidence and clinical manifestations of symptomatic dengue infection in Thai children during 2006 through 2008.

Study Design

This study is a school-based prospective open cohort study with a 9,448 person-year follow-up in children aged 3–14 years. Active surveillance for febrile illnesses was done in the studied subjects. Subjects who had febrile illness were asked to visit the study hospital for clinical and laboratory evaluation, treatment, and serological tests for dengue infection. The clinical data from medical records, diary cards, and data collection forms were collected and analyzed.

Results

Dengue infections were the causes of 12.1% of febrile illnesses attending the hospital, including undifferentiated fever (UF) (49.8%), dengue fever (DF) (39.3%) and dengue hemorrhagic fever (DHF) (10.9%). Headache, anorexia, nausea/vomiting and myalgia were common symptoms occurring in more than half of the patients. The more severe dengue spectrum (i.e., DHF) had higher temperature, higher prevalence of nausea/vomiting, abdominal pain, rash, diarrhea, petechiae, hepatomegaly and lower platelet count. DHF cases also had significantly higher prevalence of anorexia, nausea/vomiting and abdominal pain during day 3–6 and diarrhea during day 4–6 of illness. The absence of nausea/vomiting, abdominal pain, diarrhea, petechiae, hepatomegaly and positive tourniquet test may predict non-DHF.

Conclusion

Among symptomatic dengue infection, UF is most common followed by DF and DHF. Some clinical manifestations may be useful to predict the more severe disease (i.e., DHF). This study presents additional information in the clinical spectra of symptomatic dengue infection.     

An ONIOM investigation on anion recognition of alkali–metal complexes with diurea calix[4]arene receptor

The ONIOM(B3LYP/6-31G(d):AM1) optimized structures of complexes of diurea calix[4]arene receptor (L) with alkali metals Li(+), Na(+) and K(+) and their complexes with halide ions F(-), Cl(-), Br(-), oxygen-containing anions HCO(3)(-), HSO(4)(-) and CH(3)COO(-) ions were obtained. Binding energies and thermodynamic properties of complex receptors LiL(+), NaL(+) and KL(+) with these anions were determined. The binding stabilities according to binding energies of LiL(+), NaL(+) and KL(+) associated with anions computed either at the ZPVE-corrected ONIOM(B3LYP/6-31G(d):AM1) or BSSE-corrected B3LYP/6-31 + G(d,p)//ONIOM(B3LYP/6-31G(d):AM1) are in the same order: F(-) > CH(3)COO(-) ≈ HCO(3)(-) > Br(-) ≈ HSO(4)(-) ≈ Cl(-). All the receptors LiL(+), NaL(+) and KL(+) were found to be selective toward fluoride ion.     

Sensitive non-radioactive determination of aminotransferase stereospecificity for C-4' hydrogen transfer on the coenzyme

A sensitive non-radioactive method for determination of the stereospecificity of the C-4′ hydrogen transfer on the coenzymes (pyridoxal phosphate, PLP; and pyridoxamine phosphate, PMP) of aminotransferases has been developed. Aminotransferase of unknown stereospecificity in its PLP form was incubated in ²H₂O with a substrate amino acid resulted in PMP labeled with deuterium at C-4′ in the pro-S or pro-R configuration according to the stereospecificity of the aminotransferase tested. The [4′-²H]PMP was isolated from the enzyme protein and divided into two portions. The first portion was incubated in aqueous buffer with apo-aspartate aminotransferase (a reference si-face specific enzyme), and the other was incubated with apo-branched-chain amino acid aminotransferase (a reference re-face specific enzyme) in the presence of a substrate 2-oxo acid. The ²H at C-4′ is retained with the PLP if the aminotransferase in question transfers C-4′ hydrogen on the opposite face of the coenzyme compared with the reference aminotransferase, but the ²H is removed if the test and reference aminotransferases catalyze hydrogen transfer on the same face. PLP formed in the final reactions was analyzed by LC–MS/MS for the presence or absence of ²H. The method was highly sensitive that for the aminotransferase with ca. 50 kDa subunit molecular weight, only 2 mg of the enzyme was sufficient for the whole test. With this method, the use of radioactive substances could be avoided without compromising the sensitivity of the assay.     

Molecular modeling of dissociative and non-dissociative chemisorption of nitrosamine on close-ended and open-ended pristine and Stone-Wales defective (5,5) armchair single-walled carbon nanotubes

The nitrosamine adsorbed on close-ended and open-ended pristine and Stone-Wales defective (5,5) armchair single-walled carbon nanotubes (SWCNTs) was studied using the B3LYP/6-31G(d) method. Structure optimization of all possible adsorption configurations based on the combination of two nitrosamine (amino- and imino-) isomers and four types of nanotubes was carried out. The most stable configuration for the nitrosamine adsorbed on the (5,5) armchair SWCNTs was found to be dissociative chemisorption. The adsorption energies of the most stable structures of the adsorption complexes of close-ended and open-ended pristine SWCNTs with the imino isomer of nitrosamine were −127.15 and −137.14 kcal mol⁻¹, respectively.     

A DFT investigation of conformational geometries and interconversion equilibria of phenylthiosemicarbazone and its complexation with zinc

The geometrical structures of phenylthiosemicarbazone (HAPhTSC) conformers have been obtained by geometry optimizations using density functional theory (DFT) calculations at the B3LYP/6-31G(d) and B3LYP/6-311G(d,p) levels of theory. Six thioamino and 24 thioimino tautomers of HAPhTSC have been found. Six tautomerization reactions between thioamino and thioimino tautomers occurring via transition states and their corresponding activation energies have been obtained. Conformational pathways for tautomerizations and interconversions of HAPhTSC conformers have been presented. Tautomerization between the most stable species of thioamino (Atttcc) and its thioimino (Itttcct) tautomer is an endothermic reaction, H⁰=18.17 kcal mol^–1 and its log K=–13.74, at 298.15 K. Thermodynamic quantities of tautomerizations, interconversions of HAPhTSC conformers and their equilibrium constants are reported. The geometry of the zinc complex with HAPhTSC, found as a Zn(HAPhTSC)₂Cl₂ structure, has been obtained using B3LYP/6-31G(d) calculations. Binding of the Zn(HAPhTSC)₂Cl₂ complex is an exothermic and spontaneous reaction.Figure Conformational notation defined as a name consisting of a letter A for a thioamino tautomer followed by c for cis or t for trans isomerism of five dihedral angles of (C4-C3-C2-N3), (C3-C2-N3-N2), (C2-N3-N2-C1), (N3-N2-C1-N1) and (N2-C1-N1-H2), serially, or a letter I for b thioimino tautomer followed by c for cis or t for trans isomerism of six dihedral angles of (C4-C3-C2-N3), (C3-C2-N3-N2), (C2-N3-N2-C1), (N3-N2-C1-N1), (N2-C1-N1-H2) and (N2-C1-S-H1), serially.Electronic Supplementary Material Supplementary material is available for this article at     

Density functional investigation of CO adsorption on Ni-doped single-walled armchair (5,5) boron nitride nanotubes

The adsorption of CO onto Ni-doped boron nitride nanotubes (BNNTs) was investigated using density functional theory at the B3LYP/LanL2DZ level of theory. The structures of the Ni-doped BNNTs and their CO-adsorbed configurations were obtained. It was found that the strength of adsorption of CO onto Ni-doped perfect BNNTs is higher than that on defective BNNTs. The electronic properties of all of the adsorption configurations of CO on Ni-doped BNNTs are reported.

Characterization,gene cloning,and heterologous expression of β-mannanase from a thermophilic <Emphasis Type="Italic">Bacillus subtilis</Emphasis>

Bacillus subtilis BCC41051 producing a thermostable β-mannanase was isolated from soybean meal-enriched soil and was unexpectedly found to be thermophilic in nature. The extracellular β-mannanase (ManA) produced was hydrophilic, as it was not precipitated even with ammonium sulfate at 80% saturation. The estimated molecular weight of ManA was 38.0 kDa by SDS-PAGE with a pi value of 5.3. Optimal pH and temperature for mannan-hydrolyzing activity was 7.0 and 60°C, respectively. The enzyme was stable over a pH range of 5.0–11.5, and at temperatures of up to 60°C for 30 min, with more than 80% of its activity retained. ManA was strongly inhibited by Hg²⁺ (1 mM), but was sensitive to other divalent ions to a lesser degree. The gene of ManA encoded a protein of 362 amino acid residues, with the first 26 residues identified as a signal peptide. High expression of recombinant ManA was achieved in both Escherichia coli BL21 (DE3) (415.18 U/ml) and B. megaterium UNcat (359 U/ml).     

First principles investigation of oxygen adsorptions on hydrogen–terminated ZnO graphene-like nanosheets

The structures of ZnO graphene–like nanosheets (ZnOGLNS), i.e., ZnO aromatic–like (AL–ZnONS), naphthalene–like (NLL–ZnONS), pyrene–like (PRL–ZnONS), coronene–like (CNL–ZnONS) and circumcoronene–like (CCL–ZnONS) and their oxygen adsorptions were obtained using the B3LYP/LanL2DZ method. Adsorption energies of O₂ on AL–ZnONS, NLL–ZnONS, PRL–ZnONS, CNL–ZnONS and CCL–ZnONS are reported. The bond strengths of the most inner Zn–O bonds of ZnOGLNSs are in order: CCL–ZnONS > CNL–ZnONS > PRL–ZnONS. It was found that chemisorptions of O₂ occur on the hydride atoms of zinc–hydride in the ZnOGLNSs. Physisorptions of O₂ only occurring over the plane of ZnOGLNS were found. All the ZnOGLNSs are oxygen sensitive materials and would be developed to be oxygen sensor based on electrical conductivity.     

Gas adsorption on the Zn-, Pd- and Os-doped armchair (5,5) single-walled carbon nanotubes

The adsorption of NO₂, NH₃, H₂O, CO₂ and H₂ gases on the undoped, Zn–, Pd– and Os–doped armchair (5,5) single–walled carbon nanotubes (SWCNTs) were studied using density functional method. The adsorptions of these five gases on the Zn–, Pd– and Os–doped SWCNTs are obviously stronger than on the undoped SWCNT and their adsorption abilities are in the same order: NO₂ > NH₃ > H₂O > CO₂ > H₂. Adsorption energies for all the studied gases on the undoped, Zn–, Pd– and Os–doped SWCNTs computed at the B3LYP/LanL2DZ level are reported.     

A density functional theory study on peptide bond cleavage at aspartic residues: direct vs cyclic intermediate hydrolysis

In this work, peptide bond cleavages at carboxy- and amino-sides of the aspartic residue in a peptide model via direct (concerted and step-wise) and cyclic intermediate hydrolysis reaction pathways were explored computationally. The energetics, thermodynamic properties, rate constants, and equilibrium constants of all hydrolysis reactions, as well as their energy profiles were computed at the B3LYP/6-311++G(d,p) level of theory. The result indicated that peptide bond cleavage of the Asp residue occurred most preferentially via the cyclic intermediate hydrolysis pathway. In all reaction pathways, cleavage of the peptide bond at the amino-side occurred less preferentially than at the carboxy-side. The overall reaction rate constants of peptide bond cleavage of the Asp residue at the carboxy-side for the assisted system were, in increasing order: concerted < step-wise < cyclic intermediate.