Design of an Automatically Controlled Multi-Axis Stretching Device for Mechanical Evaluations of the Anterior Eye Segment.

The young eye has an accommodative ability involving lens shape changes to focus over different distances. This function gradually decreases with age, resulting in presbyopia. Greater insights into the mechanical properties of anterior eye structures can improve understanding of the causes of presbyopia. The present study aims to develop a multi-axis stretching device for evaluating the mechanical properties of the intact eye lens. A stretching device integrating the mechanical stretcher, motor, torque sensor and data transmission mechanism was designed and developed by 3D printing. The mechanical stretcher can convert rotation into radial movement, both at constant speeds, according to the spiral of Archimedes. The loading unit equipped with eight jaws can hold the eye sample tightly. The developed device was validated with a spring of known constant and was further tested with anterior porcine eye segments. The validation experiment using the spring resulted in stiffness values close to the theoretical spring constant. Findings from measurements with porcine eye samples indicated that the measured forces are within the ranges reported in the literature. The developed multi-axis stretching device has good repeatability during experiments with similar settings and can be reliably used for mechanical evaluations of the intact eye lens.

Cytotoxic compounds from marine actinomycetes: Sources, Structures and Bioactivity.

Marine actinomycetes produce a substantial number of natural products with cytotoxic activity. The strains of actinomycetes were isolated from different sources like fishes, coral, sponges, seaweeds, mangroves, sediments etc. These cytotoxic compounds can be categorized briefly into four classes: polyketides, non-ribosomal peptides and hybrids, isoprenoids and hybrids, and others, among which majority are polyketides (146). Twenty two out of the 254 compounds showed potent cytotoxicity with IC50 values at ng/mL or nM level. This review highlights the sources, structures and antitumor activity of 254 natural products isolated from marine actinomycetes, which were new when they were reported from 1989 to 2020.

Reduced mother-to-child transmission of hepatitis B after implementation of completely charge-free active-passive immunoprophylaxis: an observational cohort study.

Objectives: China has implemented universal hepatitis B vaccination since 2002 and provided charge-free hepatitis B immunoglobulin (HBIG) to infants of HBV-infected mothers since July 2011. We aimed to compare mother-to-child transmission (MTCT) in children born before and since July 2011.Methods: In total, 5,149 children of HBV-infected mothers were tested for HBV markers. Group one contained 1,160 children born during August 2002-June 2011 and group two contained 3,989 children born during July 2011-June 2016.Results: In total, 92 (1.8%, 95% confidence interval [95%CI] 1.4-2.2) children were infected with HBV. None (0%, 95%CI 0.0-0.1) of 3,716 children of mothers with negative hepatitis B e antigen (HBeAg) was infected, whereas 92 (6.4%, 95%CI 5.2-7.8) of 1,433 children of HBeAg-positive mothers were infected (p < 0.0001). Among children of HBeAg-positive mothers, MTCT occurred in 10.3% (19/185) (95%CI 6.3-15.6) in group one and 5.8% (73/1,248) (95%CI 4.6-7.3) in group two (p = 0.02).Conclusions: Implementing charge-free active-passive immunoprophylaxis greatly reduces MTCT of HBV in children of HBeAg-positive mothers, highlighting the importance of timely administration of both hepatitis B vaccine and HBIG to prevent MTCT. The still remaining MTCT suggests that reducing maternal virus load before delivery is an additional important measure.

[A new polyketide from marine-derived Streptomyces sp.MDW-06].

To isolate and identify secondary metabolites of marine-derived Streptomyces sp.MDW-06,the isolations and purifications of compounds were performed by means of column chromatography over silica gel. And their structures were elucidated through the spectroscopic analysis of MS,NMR and specific rotations. The bioactivities were assayed by paper diffusion and DPPH method. From the fermentation broth of marine-derived Streptomyces sp.MDW-06,five compounds( 1-5) were isolated and identified as streptopentanoic acid( 1),germicidin A( 2),germicidin B( 3),isogermicidin A( 4),isogermicidin B( 5) and oxohygrolidin( 6),respectively. Compound 1 is a new compound. Compound 1 shows DPPH radical scavenging activity with 36. 4% at 100 mg·L~(-1).