[Nutritional recovery after discharge in hospitalized children with malnutrition].

OBJECTIVE: To investigate the nutritional recovery status of children with moderate or severe malnutrition during hospitalization after discharge. METHODS: The children with moderate or severe malnutrition were given nutrition support during hospitalization. They received a regular follow-up and nutrition guidance after discharge. The weight-for-age and height-for-age Z-scores reaching above -2 SD were considered the nutrition criterion for ending follow-up. RESULTS: Among the 298 children with moderate or severe malnutrition, 174 (58.4%) reached the criterion for ending follow-up, 100 (33.6%) were lost to follow-up, 18 (6.0%) died, and 6 (2.0%) did not reach the criterion for ending follow-up after 18 months of follow-up. The children with malnutrition in the department of surgery had a significantly higher proportion of children reaching the criterion for ending follow-up than those in the department of internal medicine (P<0.05). The children with severe malnutrition had a significantly higher loss to follow-up rate than those with moderate nutrition (P<0.05). The majority of children with emaciation reached the criterion for ending follow-up at month 3 after discharge, while those with growth retardation reached such the criterion at months 3-6 after discharge. Up to 1 year after discharge, more than 80% of the children with different types of malnutrition reached the nutrition criterion for ending follow-up. CONCLUSIONS: Most of the children with malnutrition who adhere to follow-up can reach the expected nutrition criterion within 1 year after discharge. The children with growth retardation have slower nutritional recovery than those with emaciation.

Improved sulfoalkylbetaine-based organic-silica hybrid monolith for high efficient hydrophilic interaction liquid chromatography of polar compounds.

A novel sulfoalkylbetaine-based zwitterionic organic-silica hybrid monolith was synthesized by using 3-dimethyl-(3-(N-methacrylamido) propyl) ammonium propane sulfonate (DMMPPS, neutral sulfoalkyl-betaine monomer). The added amount of zwitterionic monomer was significantly increased when DMMPPS was used instead of the conventionally used acidic sulfoalkyl-betaine monomer, that is, the N,N-dimethyl-N-methacryloxyethyl-N-(3-sulfopropyl) ammonium betaine, and this led to a significantly improved hydrophilicity of the monolith. The DMMPPS-based organic-silica hybridmonolith exhibited good mechanical stability and excellent separation performance. About ∼20 mµ plate height (corresponding to column efficiency of ∼50,000 plates/m) was obtained for nucleoside at the linear velocity of 1 mm/s. The proposed monolithic column was successfully applied to separate purines/pyrimidines, nucleotides, and tryptic digest of bovine hemoglobin in a nano-HILIC mode, and the results demonstrated that such monolith has the potential for separation of a variety of hydrophilic substances.

Graphene oxide-peptide nanocomplex as a versatile fluorescence probe of protein kinase activity based on phosphorylation protection against carboxypeptidase digestion.

The research on complicated kinomics and kinase-target drug discovery requires the development of simple, cost-effective, and multiplex kinase assays. Herein, we propose a novel and versatile biosensing platform for the detection of protein kinase activity based on graphene oxide (GO)-peptide nanocomplex and phosphorylation-induced suppression of carboxypeptidase Y (CPY) cleavage. Kinase-catalyzed phosphorylation protects the fluorophore-labeled peptide probe against CPY digestion and induces the formation of a GO/peptide nanocomplex resulting in fluorescence quenching, while the nonphosphopeptide is degraded by CPY to release free fluorophore as well as restore fluorescence. This GO-based nanosensor has been successfully applied to sensitively detect two model kinases, casein kinase (CKII) and cAMP-dependent protein kinase (PKA) with low detection limits of 0.0833 mU/µL and 0.134 mU/µL, respectively. The feasibility of this GO-based sensor was further demonstrated by the assessment of kinase inhibition by staurosporine and H-89, in vitro kinase assay in cell lysates, and simultaneous detection of CKII and PKA activity. Moreover, the GO-based fluorescence anisotropy (FA) kinase assay has been also developed using GO as a FA signal amplifier. The proposed sensor is homogeneous, facile, universal, label-free, and applicable for multiplexed kinase assay, presenting a promising method for kinase-related biochemical fundamental research and inhibitor screening.

Cage-like silica nanoparticles-functionalized silica hybrid monolith for high performance capillary electrochromatography via "one-pot" process.

A cage-like silica nanoparticles-functionalized silica hybrid monolith for high performance capillary electrochromatography (CEC) has been prepared via "one-pot" process. In this process, the polycondensation of hydrolyzed alkoxysilanes and in situ reaction of mercaptopropyltrimethoxysilane (MPTS) with sodium 3-mercapto-1-propanesulfonate modified octavinyloctasilasesquioxane (MPS-OVS) simultaneously occurred in a pretreated capillary. The characterization and evaluation results indicated that the obtained MPS-OVS hybrid monolithic capillary column has homogeneous macroporous morphology with a permeability of 5.37×10(-13)m(2) and strong electro osmotic flow (EOF) over a wide pH range from 2.7 to 11.2. The EOF on the MPS-OVS hybrid monolithic column reached its maximum of 0.327cm(2)kV(-1)s(-1) at pH 9.7. The best theoretical efficiency of ∼470,000plates/m was obtained for 2-aminophenol in CEC. Anilines and phenols were well separated on the MPS-OVS hybrid monolithic column by CEC, indicating typical reversed-phase and cation-exchange chromatographic retention mechanisms of the column. The monolith was further applied to the separation of bovine serum albumin (BSA) tryptic digests, and the result indicated its potential in the analysis of some complex samples.

One-pot synthesis of (3-sulfopropyl methacrylate potassium)-silica hybrid monolith via thiol-ene click chemistry for CEC.

A novel (3-sulfopropyl methacrylate potassium)-silica hybrid monolithic column for CEC has been prepared by a simple one-pot approach based on efficient thiol-ene click chemistry. In this process, the polycondensation of hydrolyzed alkoxysilanes and in situ click reaction of vinyl groups on 3-sulfopropyl methacrylate potassium and thiol groups on the precondensed siloxanes simultaneously occurred in a pretreated capillary. Homogeneous monolithic matrix with large through-pores tightly bonded to the inner wall of the capillary was shown by optical microscope and SEM. The minimum plate height of this hybrid monolithic column was determined as 3.9 µm for thiourea. Anilines, alkylbenzenes, and phenols were well separated on this hybrid monolithic column by CEC, which indicated typical reversed-phase and cation-exchange chromatographic retention mechanisms of the column.

One-pot synthesis of N-methylimidazolium-based porous polymer monolith for capillary electrochromatography via free radical copolymerization and quaterisation.

One-pot synthesis of porous polymer monolith decorated with N-methylimidazolium in a capillary was described. The polymer matrix was synthesized by in situ copolymerization and quaterization of 3-chloro-2-hydroxylpropyl methacrylate (CHPMA), ethylene dimethacrylate (EDMA), and N-methylimidazole (N-MIz). The influencing factors including amount of cross-linkers, composition of porogenic solvents, and polymerization temperature on the formation of the monolithic column were investigated. The monolithic column exhibited high column efficiency for thiourea, up to 135 000 plates per meter, and phenylmethanol, up to 102 000 plates per meter. Different types of compounds including alkylbenzenes, phenols, and inorganic anions were successfully baseline separated by capillary electrochromatography (CEC). The separation of theses analytes on the column indicated typical reversed-phase and anion-exchange chromatographic retention mechanism.

Synthesis of sulfo/vinyl biphasic silica hybrid monolithic capillary column and its application to on-column preconcentration for capillary electrochromatography.

A novel method to synthesize sulfo/vinyl biphasic silica hybrid monolithic column in one step was developed for on-column preconcentration. In this method, sulfo-based segment is located at the inlet of capillary column, which acts as preconcentration column. It is synthesized by polymerization of 3-sulfopropyl methacrylate potassium salt (SPMA) and vinyltrimethoxysilane (VTMS) with tetramethoxysilane (TOMS). Close to the preconcentration column, a vinyl functionalized segment is formed and serves as separation column. It is synthesized by polymerization of only VTMS with TOMS. Vinyl groups on vinyl functionalized segment are modified with ligand containing sulfhydryl group, such as octadecanethiol (C(18)-SH for short), 6-mercapto-1-hexanol (HO-C(6)-SH for short), via thiol-ene click reaction. The interface between the two segments is seamless and without any dead volume. The applicability of this system is demonstrated by successful separation of closely related amines including p-phenylenediamine, aniline, p-toluidine, N-methyl aniline, N,N'-dimethylaniline, and diphenylamine. Good separation and enrichment are obtained. The proposed system is also successfully applied to complex biological samples, such as peptide, diluted BSA hydrolysate, and the results indicate that the system has a capability for preconcentration of low abundance peptides.

Modification of VTMS hybrid monolith via thiol-ene click chemistry for capillary electrochromatography.

An n-octadecanethiol (C(18))/3-mercapto-1-propane-sulfonate (MPS) modified organic-inorganic hybrid silica monolithic column possessing vinyl ligands through thiol-ene click chemistry for capillary electrochromatography (CEC) is described. The proposed column is prepared via the sol-gel process by in situ co-condensation using vinyltrimethoxysilane (VTMS) and tetra-methoxysilane (TMOS) as precursors. Examination by SEM shows that the capillary has homogenous macroporous morphology and is well attached to the inner wall of the capillary. The obtained C(18)-MPS-VTMS silica hybrid monolithic column demonstrated an enhanced hydrophilic property and could be applied as a reversed-phase stationary phase in CEC directly. Compared with unmodified VTMS silica hybrid monolithic column, stronger EOF was observed using this monolithic column. VTMS/TOMS ratios in the reaction mixture were varied and 1:3 was found to be optimum. Good separations of benzenes, aromatic amines, acids and peptides were achieved, the lowest plate height of ≈ 3µm was obtained, the peak symmetry range from 0.98 to 1.29. The resulting C(18)-MPS-VTMS silica hybrid monolithic column can be used in different separation modes, including reversed phase mode and ion exchange mode.

Enzyme-regulated activation of DNAzyme: a novel strategy for a label-free colorimetric DNA ligase assay and ligase-based biosensing.

The DNA nick repair catalyzed by DNA ligase is significant for fundamental life processes, such as the replication, repair, and recombination of nucleic acids. Here, we have employed ligase to regulate DNAzyme activity and developed a homogeneous, colorimetric, label-free and DNAzyme-based strategy to detect DNA ligase activity. This novel strategy relies on the ligation-trigged activation or production of horseradish peroxidase mimicking DNAzyme that catalyzes the generation of a color change signal; this results in a colorimetric assay of DNA ligase activity. Using T4 DNA ligase as a model, we have proposed two approaches to demonstrate the validity of the DNAzyme strategy. The first approach utilizes an allosteric hairpin-DNAzyme probe specifically responsive to DNA ligation; this approach has a wide detection range from 0.2 to 40 U mL(-1) and a detection limit of 0.2 U mL(-1). Furthermore, the approach was adapted to probe nucleic acid phosphorylation and single nucleotide mismatch. The second approach employs a "split DNA machine" to produce numerous DNAzymes after being reassembled by DNA ligase; this greatly enhances the detection sensitivity by a signal amplification cascade to achieve a detection limit of 0.01 U mL(-1).

Vinyl functionalized silica hybrid monolith-based trypsin microreactor for on line digestion and separation via thiol-ene "click" strategy.

A novel thiol-ene "click" strategy for the preparation of monolithic trypsin microreactor was proposed. The hybrid organic-inorganic monolithic capillary column with ene-functionality was fabricated by sol-gel process using tetramethoxysilane (TMOS) and γ-methacryloxypropyltrimethoxysilane (γ-MAPS) as precursors. The disulfide bonds of trypsin were reduced to form free thiol groups. Then the trypsin containing free thiol groups was attached on the γ-MAPS hybrid monolithic column with ene-functionality via thiol-ene click chemistry to form a trypsin microreactor. The activity of the trypsin microreactor was characterized by detecting the substrate (Nα-p-tosyl-L-arginine methyl ester hydrochloride, TAME) and the product (Nα-p-tosyl-L-arginine, TA) with on-line capillary zone electrophoresis. After investigating various synthesizing conditions, it was found that the microreactor with poly(N,N'-methylenebisacrylamide) as spacer can deliver the highest activity, yielding a rapid reaction rate. After repeatedly sampling and analyzing for 100 times, the monolithic trypsin microreactor still remained 87.5% of its initial activity. It was demonstrated that thiol-ene "click" strategy for the construction of enzyme microreactor is a promising method for the highly selective immobilization of proteins under mild conditions, especially enzymes with free thiol radicals.

Synthetic approach to stop-codon scanning mutagenesis.

A general combinatorial mutagenesis strategy using common dimethoxytrityl-protected mononucleotide phosphoramidites and a single orthogonally protected trinucleotide phosphoramidite (Fmoc-TAG; Fmoc = 9-fluorenylmethoxycarbonyl) was developed to scan a gene with the TAG amber stop codon with complete synthetic control. In combination with stop-codon suppressors that insert natural (e.g., alanine) or unnatural (e.g., p-benzoylphenylalanine, Bpa) amino acids, a single DNA library can be used to incorporate different amino acids for diverse purposes. Here, we scanned TAG codons through part of the gene for a model four-helix bundle protein, Rop, which regulates the copy number of ColE1 plasmids. Alanine was incorporated into Rop for mapping its binding site using an in vivo activity screen, and subtle but important differences from in vitro gel-shift studies of Rop function are evident. As a test, Bpa was incorporated using a Phe14 amber mutant isolated from the scanning library. Surprisingly, Phe14Bpa-Rop is weakly active, despite the critical role of Phe14 in Rop activity. Bpa is a photoaffinity label unnatural amino acid that can form covalent bonds with adjacent molecules upon UV irradiation. Irradiation of Phe14Bpa-Rop, which is a dimer in solution like wild-type Rop, results in covalent dimers, trimers, and tetramers. This suggests that Phe14Bpa-Rop weakly associates as a tetramer in solution and highlights the use of Bpa cross-linking as a means of trapping weak and transient interactions.

Sensitive bifunctional aptamer-based electrochemical biosensor for small molecules and protein.

In this paper, a bifunctional electrochemical biosensor for highly sensitive detection of small molecule (adenosine) or protein (lysozyme) was developed. Two aptamer units for adenosine and lysozyme were immobilized on the gold electrode by the formation of DNA/DNA duplex. The detection of adenosine or lysozyme could be carried out by virtue of switching structures of aptamers from DNA/DNA duplex to DNA/target complex. The change of the interfacial feature of the electrode was characterized by cyclic voltammertic (CV) response of surface-bound [Ru(NH(3))(6)](3+). On the other hand, DNA functionalized Au nanoparticles (DNA-AuNPs) were used to enhance the sensitivity of the aptasensor because DNA-AuNPs modified interface could load more [Ru(NH(3))(6)](3+) cations. Thus, the assembly of two aptamer-contained DNA strands integrated with the DNA-AuNPs amplification not only improves the sensitivity of the electrochemical aptasensor but also presents a simple and general model for bifunctional aptasensor. The proposed aptasensor has low detection limit (0.02 nM for adenosine and 0.01 microg mL(-1) for lysozyme) and exhibits several advantages such as high sensitivity and bifunctional recognition.

De novo biosynthesis versus sequestration: a network of transport systems supports in iridoid producing leaf beetle larvae both modes of defense.

In the larval chrysomelines the de novo synthesis of monoterpenoids (iridoids) is believed to represent the ancestral state in the evolution of chemical defenses. Here we demonstrate that the iridoid producing larvae of Plagiodera versicolora and Phratora laticollis have the potential to sequester precursors from food. In nature, iridoids may even have a dual origin, namely plant-derived and de novo produced. The ability to sequester plant-derived precursors was proved by (i) (13)C-labelling of the terpenoids in the food plant, (ii) by larval feeding on leaves impregnated with analogs and labelled putative precursors for iridoid biosynthesis; and (iii) by injection of the precursors into the hemolymph followed by mass spectroscopic analysis of their distribution in the hemolymph, defensive secretion, and faeces. The experimental findings support a network of transport systems which allows a broader range of glucosides to enter and to leave the hemocoel, while only the appropriate precursor, 8-hydroxygeraniol-8-O-beta-d-glucoside, is channelled to the reservoir and processed to iridoids. The dual system of de novo biosynthesis and sequestration of phytogenic precursors may have favoured the larvae to shift from one host plant to another without losing their defense.

Direct electrochemistry of glucose oxidase and biosensing for glucose based on boron-doped carbon nanotubes modified electrode.

Due to their unique physicochemical properties, doped carbon nanotubes are now extremely attractive and important nanomaterials in bioanalytical applications. In this work, selecting glucose oxidase (GOD) as a model enzyme, we investigated the direct electrochemistry of GOD based on the B-doped carbon nanotubes/glassy carbon (BCNTs/GC) electrode with cyclic voltammetry. A pair of well-defined, quasi-reversible redox peaks of the immobilized GOD was observed at the BCNTs based enzyme electrode in 0.1M phosphate buffer solution (pH 6.98) by direct electron transfer between the protein and the electrode. As a new platform in glucose analysis, the new glucose biosensor based on the BCNTs/GC electrode has a sensitivity of 111.57 microA mM(-1)cm(-2), a linear range from 0.05 to 0.3mM and a detection limit of 0.01mM (S/N=3). Furthermore, the BCNTs modified electrode exhibits good stability and excellent anti-interferent ability to the commonly co-existed uric acid and ascorbic acid. These indicate that boron-doped carbon nanotubes are the good candidate material for the direct electrochemistry of the redox-active enzyme and the construction of the related enzyme biosensors.

Thermal decomposition and kinetics studies on 1,4-dinitropiperazine (DNP).

DNP, a nitramine, has been studied with regard to the kinetics and mechanism of thermal decomposition, using thermogravimetry (TG), differential thermal analysis (DTA), infrared (IR) spectroscopy, and differential scanning calorimetry (DSC). The IR spectra of DNP have also been recorded and the kinetics of thermolysis has been followed by non-isothermal TG. The activation energy of the solid-state process was determined using Flynn-Wall-Ozawa method. The actual reaction mechanism obeyed nucleation and growth model, Avramie Erofeev function (n=1) with integral form Galpha=-ln(1-alpha) (alpha=0.10-0.65). Ea and A were determined to be 116.51 kJ/mol and 10(10.52) s(-1). The T/Jump FT-IR analysis showed that CH2O, NO2, and NO are produced in larger amounts than CO2 and HCN. The cleavage of the N-N and C-N bond appears to be the primary step in the thermolysis of DNP.

Improved determination of 5-fluorouracil and its prodrug tegafur in pharmaceuticals by large-volume sample stacking in CE.

On-line determination of the anti-tumor drug 5-fluorouracil (5-FU) and its prodrug, tegafur (TF) was achieved for the first time by capillary electrophoresis with large-volume sample stacking (CE-LVSS). The optimal electrophoretic buffer consisted of 30 mM phosphate buffer at pH 8.0. Without the LVSS procedure, the limits of detection (LOD) were 600.5 ng/mL and 771.4 ng/mL for 5-FU and TF, respectively. With the LVSS procedure, the sensitivity was significantly improved by about two orders of magnitude (the LODs of 5-FU and TF were decreased to 7.9 ng/mL and 6.5 ng/mL, respectively). The %RSD was less than 5%. This method compared favorably with other reported techniques and was applied successfully to the quantitative analysis of anti-tumor drugs in commercial injection preparations. The results show that the method is simple, fast (less than 3 min), highly selective, and sensitive.

To improve the quantification sensitivity of large molecular weight compounds--with ginsenosides as example.

High cone voltage was used to improve the quantification sensitivity of large molecular weight compounds in high-performance liquid chromatography electrospray ionization mass spectrometry (HPLC/ESI-MS), with ginsenosides as example. Investigations on the effect of cone voltage showed that within a voltage range of 30-130 V, for all the ginsenosides tested, i.e., Rb(1), Rb(2), Rc, Rd, Re, R(f) and R(g1), an increase in the applied cone voltage can significantly increase the sensitivity of the method. The maximum sensitivity in the determination decreases with the decreasing molecular weight of the ginsenosides in the order of Rb(1) > Rb(2) > Rc > Re > Rd > R(g1) > R(f). At the high cone voltage of 130 V, both molecular weight and structural information was obtained from a single mass spectrum. It can also be used for isomer differentiation and determination of O-glycosidic linkages in ginsenosides. Linear relationships between the peak area response and concentration were observed in the range of 50-2 x 10(5) ng/mL, with the correlation coefficients >0.99. The limits of detection reached down to pg for ginsenosides. The method was successfully applied to the determination of ginsenosides in commercial ginseng samples.

A label-free electrochemical immunoassay for carcinoembryonic antigen (CEA) based on gold nanoparticles (AuNPs) and nonconductive polymer film.

A simple and sensitive label-free electrochemical immunoassay electrode for detection of carcinoembryonic antigen (CEA) has been developed. CEA antibody (CEAAb) was covalently attached on glutathione (GSH) monolayer-modified gold nanoparticle (AuNP) and the resulting CEAAb-AuNP bioconjugates were immobilized on Au electrode by electro-copolymerization with o-aminophenol (OAP). Electrochemical impedance spectroscopy and cyclic voltammetry studies demonstrate that the formation of CEA antibody-antigen complexes increases the electron transfer resistance of [Fe(CN)(6)](3-/4-) redox pair at the poly-OAP/CEAAb-AuNP/Au electrode. The use of CEA antibody-AuNP bioconjugates and poly-OAP film could enhance the sensitivity and anti-nonspecific binding of the resulting immunoassay electrode. The preliminary application of poly-OAP/CEAAb-AuNP/Au electrode for detection of CEA was also evaluated.

Sequestration of plant-derived phenolglucosides by larvae of the leaf beetle Chrysomela lapponica: thioglucosides as mechanistic probes.

Feeding larvae of Chrysomela lapponica (Coleoptera: Chrysomelidae) acquire characteristic O-glucosides from the leaves of their food plants. The glucosides are selectively channeled from the gut to the defensive gland. Subsequent enzymatic transformations generate a blend of different defensive compounds, e.g., salicylaldehyde and two series of 2-methylbutyl and isobutyryl esters. By using systematically modified and hydrolysis-resistant thioglucosides as structural mimics of the plant-derived glucosides, e.g., salicin and its o-, m-, and p-isomers 1, 2, and 3; o-, m-, and p-cresols 5, 6, 7; along with thioglucosides of 2-phenylethanol 9 and (3Z)-hexenol 10, we demonstrated that the larvae of C. lapponica are able to sequester a broad range of structurally different thioglucosides with comparable efficiency. This sharply contrasts with the sequestration habitus previously observed in Chrysomela populi and Phratora vitellinae, which secrete almost pure salicylaldehyde and posses a highly specific transport mechanism for salicin (Kuhn et al., Proc. Natl. Acad. Sci. USA 101:13808-13813, 2004). Also, neither C. lapponica nor C. populi sequester in their gland the thioglucoside of 8-hydroxygeraniol, the mimic of the glucoside specifically transported by larvae secreting iridoid monoterpenes (Phaedon cochleariae, Gastrophysa viridula). Accordingly, leaf beetle larvae possess selective membrane carriers in their gut and their defensive systems that match the orientation of the functional groups of glucosides from their food plants probably by embedding the substrate in a network of hydrogen bonds inside the membrane carriers. The synthesis and the spectroscopic properties of the test compounds along with a comparative evaluation of the transport capabilities of larvae of C. populi and C. lapponica are described.

Simultaneous determination of nine aristolochic acid analogues in medicinal plants and preparations by high-performance liquid chromatography.

By optimizing the extraction, separation and analytical conditions, a simple, reliable and effective high-performance liquid chromatography method coupled with photodiode array detector (HPLC-DAD) is presented for simultaneous determination of nine aristolochic acid (AA) analogues, i.e., AA I, AA II, AA C, AA D, 7-OH AA I, aristolic acid, AL II, AL III and AL IV, in twelve medicinal herbs and two preparations. The separation was completed on a C18 column with aqueous methanol containing 0.2% (V/V) acetic acid as mobile phase. Linearities of around two orders of magnitude were obtained with correlation coefficients exceeding 0.9950. Satisfactory intra-day and inter-day precisions were achieved with R.S.D.s less than 4.35%, and the average recovery factors obtained were in the range of 88.4-98.8%. The proposed method appears to be suitable for use as a tool for safety assurance and quality control for commercially available suspect samples containing aristolochic acid analogues.