[Effects of eye exercises on axial eye elongation in junior students]

Objective: To evaluate the association between the eye exercises and one-year axial eye elongation in grade 7 students in Beijing. Methods: Sampling was performed using a multistage random cluster approach, and 1 443 students of grade 7 were selected from 9 middle schools in 6 districts for the baseline survey. Data were collected by questionnaires and axial length measurement. Multiple linear regression analysis was used to evaluate the association between eye exercises and excessive axial eye elongation. Results: Among 1 197 (82.95%) students with complete information, the median (Q_R) age was 12.00 (1.00) years old, girls accounted for 44.28%, and the median (Q_R) axial eye elongation was 0.22 (0.18) mm. In the multiple linear regression analysis, the frequency of eye exercises was significantly correlated with excessive axial eye elongation in boys (β=-0.135, 95%CI:-0.253--0.018) but not in girls (β=-0.075, 95%CI:-0.207- 0.058) after adjusting for sex, age, body height, the number of myopic parents, time spent outdoors and time spent on reading and writing outside class; while the seriousness of eye exercises was not significantly associated with axial eye elongation in boys (β=-0.028, 95%CI: -0.114-0.058) and girls (β=-0.035, 95%CI: -0.134-0.064). Conclusion: The increased frequency of eye exercises is beneficial to control the axial eye elongation in boys in Beijing.

Comprehensive study of the adsorption of an acylhydrazone derivative by serum albumin: unclassical static quenching

NCH binds to both HSA and BSA in site I and causes unclassical static quenching.

Concurrent obtaining of aromatic (R)-2-hydroxyacids and aromatic 2-ketoacids by asymmetric oxidation with a newly isolated Pseudomonas aeruginosa ZJB1125

Pseudomonas aeruginosa ZJB1125 harboring a stereoselective 2-hydroxyacid dehydrogenase (2-HADH) can catalyze asymmetric oxidation of mandelic acid and 2-chloromandelic acid into (R)-isomers and corresponding 2-ketoacids with high activity and enantioselectivity, while no consecutive oxidation of 2-ketoacids was observed during whole-cell catalysis. The 2-HADH in P. aeruginosa ZJB1125 is a FMN-dependent flavoprotein and did not require NAD(P)⁺ as cofactors to catalyze the oxidation reaction. Enzyme activity staining identified 2-HADH as the key enzyme that enantioselectively oxidized (S)-hydroxyacid to 2-ketoacid. The 2-HADH in P. aeruginosa ZJB1125 is inducible and 2-chloromandelic acid was found to induce its synthesis efficiently. The bacterium displayed pretty high activity and enantioselectivity for most of the aromatic 2-hydroxyacids examined, and have a potential for the concurrent obtaining of aromatic (R)-2-hydroxyacids and aromatic 2-ketoacids in near theoretical conversions. Using a simple organic extract process, aromatic (R)-2-hydroxyacids and aromatic 2-ketoacids can be effectively separated from the biocatalytic reaction mixture with high yield (>95%). This work provided a novel method for the concurrent obtaining of aromatic (R)-2-hydroxyacids and aromatic 2-ketoacids by oxidation of aromatic 2-hydroxyacids in one-step biotransformation, which would be a valuable process due to its high atom economy.

Spectroscopic studies on the interactions between CdTe quantum dots coated with different ligands and human serum albumin

This paper investigates the interactions between human serum albumin (HSA) and CdTe quantum dots (QDs) with nearly identical hydrodynamic size, but capped with four different ligands (MPA, NAC, and GSH are negatively charged; CA is positively charged) under physiological conditions. The investigation was carried out using fluorescence spectroscopy, circular dichroism (CD) spectra, UV-vis spectroscopy, and dynamic light scattering (DLS). The results of fluorescence quenching and UV-vis absorption spectra experiments indicated the formation of the complex of HSA and negatively charged QDs (MPA-CdTe, NAC-CdTe, and GSH-CdTe), which was also reconfirmed by the increasing of the hydrodynamic radius of QDs. The K(a) values of the three negatively charged QDs are of the same order of magnitude, indicating that the interactions are related to the nanoparticle itself rather than the ligands. ΔH<0 and ΔS>0 implied that the electrostatic interactions play predominant roles in the adsorption process. Furthermore, it was also proven that QDs can induce the conformational changes of HSA from the CD spectra and the three-dimensional fluorescence spectra of HSA. However, our results demonstrate that the interaction mechanism between the positively charged QDs (CA-CdTe) and HSA is significantly different from negatively charged QDs. For CA-CdTe QDs, both the static and dynamic quenching occur within the investigated range of concentrations. According to the DLS results, some large-size agglomeration also emerged.

Synthesis of three novel anionic gemini surfactants and comparative studies of their assemble behavior in the presence of bovine serum albumin

Three novel anionic sulfonate gemini surfactants, sodium 4,4'-(10,19-dioxo-9,11,18,20-tetraazaoctacosane-9,20-diyl) dibenzenesulfonate (Surfactant I), sodium 4,4'-(12,21-dioxo-11,13,20,22-tetraazadotriacontane-11,22-diyl) dibenzenesulfonate (Surfactant II), and sodium 4,4'-(14,23-dioxo-13,15,22,24-tetraazahezatriacontane-13,24-diyl) dibenzenesulfonate (Surfactant III), with different lengths of hydrophobic tail have been synthesized, and their assembly behavior in the presence of bovine serum albumin (BSA) has been studied using spectral methods and molecular modeling methods at physiological pH and 298 K. Critical micelle concentrations (CMCs) of the three surfactants have been determined by surface tension measurements. Despite the obvious decrease of CMC with the increase of tail length, fluorescence spectra have shown much closer CAC in the presence of BSA. Surfactant II shows the highest CAC of 3.19 × 10(-5) mol L(-1) compared with the other two. The polarity of the microenvironment in BSA-surfactant systems has been investigated using pyrene as the probe. In addition, far-UV CD spectra studied the change of the secondary structure content of BSA caused by the three surfactants. The features of the assembly behavior were discussed by three concentration regions. Surfactant II could unfold the protein much more efficiently than the other two surfactants at low concentration, but at high concentration, the change of the secondary structure and the formation of hydrophobic microenvironment show a direct relationship to the length of the hydrophobic tail with the increase of the surfactant concentration.

[Kindling model of SD rats induced by injection of PTX intraperitoneally]

OBJECTIVE

To observe the kindling model of Sprague-Dawley (SD) rats induced by injection of different doses of picrotoxin (PTX) intraperitoneally, and to evaluate the effect of the drug on the model.

METHODS

SD rats were devided randomly into four groups: control group, epilepsy Group I (PTX, 1.5 mg.kg-1.d-1), epilepsy Group II (PTX, 2 mg.kg-1.d-1) and the phenobarbital group. The kindling model of rats was induced by daily injection of PTX intraperitoneally. The seizures in the rats were observed, and the results of electroencephalography (EEG) were recorded.

RESULTS

On the 20th day after injection of PTX, 71% SD rats were kindled in epilepsy Group I; 4 rats were dead, 2 rats were at stage IV of convulsions, and 2 rats were at stage V of convulsions in epilepsy Group II; 17% rats were kindled in the phenobarbital group. The EEG demonstrated spike discharges in the kindled rats.

CONCLUSIONS

In this models, the better dose of PTX is 1.5 mg.kg-1.d-1, and phenobarbital sodium can protect SD rats injected PTX intraperitoneally from seizure.