Characterisation of thickness changes in the peripapillary retinal nerve fibre layer in patients with Leber's hereditary optic neuropathy.

BACKGROUND: Limited studies have identified the changes in peripapillary retinal nerve fibre layer (pRNFL) thickness in patients with chronic Leber's hereditary optic neuropathy (LHON) at different stages of the disease. We aimed to characterise the pRNFL thickness changes in patients with LHON having m.11778G>A (MT-ND4) mutation. METHODS: This retrospective cross-sectional study included 221 eyes from patients with LHON (n=145)-classified into seven groups according to disease duration-and 52 eyes from healthy controls (n=26). All subjects underwent pRNFL examinations. pRNFL thickness of the superior, nasal and inferior, and temporal quadrants, and the 360° average were measured. RESULTS: Within 3 months of onset, the temporal pRNFL thickness decreased significantly, whereas the remaining quadrants and the average pRNFL thickness initially increased. The temporal quadrant (p<0.01) and average pRNFL thickness (p=0.02) significantly decreased at 3-6 months. Excluding that in the nasal quadrant (p=0.93), pRNFL thickness significantly decreased in all other quadrants at 6-9 months. At 9-12 months, the average and individual quadrant pRNFL thicknesses continued to decrease. Compared with 12-24 months, the pRNFL thickness was thinner at 24-60 months and >60 months. CONCLUSIONS: The papillomacular bundle was affected first and preferentially in LHON. pRNFL thickness initially increased and then decreased, corresponding to the retinal ganglion cell swelling and apoptosis. pRNFL thinning first occurred in the temporal quadrant, followed by the inferior and superior quadrants, and finally, the nasal quadrant. pRNFL continued to thin slowly in some quadrants even after 60 months.

UV and Resonance Raman Spectroscopic and Theoretical Studies on the Solvent-Dependent Ground and Excited-State Thione → Thiol Tautomerization of 4,6-Dimethyl-2-mercaptopyrimidine (DMMP).

The vibrational spectra of 4,6-dimethyl-2-mercaptopyrimidine (DMMP) in acetonitrile, methanol, and water were assigned by resonance Raman spectroscopy through a combination of Fourier-transform infrared spectroscopy (FT-IR), FT-Raman UV-vis spectroscopy, and density functional theoretical (DFT) calculations. The FT-Raman spectra show that the neat solid DMMP is formed as a dimer due to intermolecular hydrogen bonding. In methanol and water, however, the majority of the Raman spectra were assigned to the vibrational modes of DMMP(solvent) n ( n = 1-4) clusters containing NH···O hydrogen bonds. The intermolecular NH···O hydrogen bond interactions, which are key constituents of the stable DMMP thione structure, revealed significant structural differences in acetonitrile, methanol, and water. In addition, UV-induced hydrogen transfer isomeric reactions between the thione and thiol forms of DMMP were detected in water and acetonitrile. DFT calculations indicate that the observed thione → thiol tautomerization should occur easily in lower excited states in acetonitrile and water.

Experimental Investigation of the Acoustic Nonlinear Behavior in Granular Polymer Bonded Explosives with Progressive Fatigue Damage.

The measurement of acoustic nonlinear response is known as a promising technique to characterize material micro-damages. In this paper, nonlinear ultrasonic approach is used to characterize the evolution of fatigue induced micro-cracks in polymer bonded explosives. The variations of acoustic nonlinearity with respect to fatigue cycles in the specimens are obtained in this investigation. The present results show a significant increase of acoustic nonlinearity with respect to fatigue cycles. The experimental observation of the correlation between the acoustic nonlinearity and fatigue cycles in carbon/epoxy laminates, verifies that an acoustic nonlinear response can be used to evaluate the progressive fatigue damage in the granular polymer bonded explosives. The sensitivity comparison of nonlinear and linear parameters of ultrasonic waves in the specimens shows that nonlinear acoustic parameters are more promising indicators to fatigue induced micro-damage than linear ones. The feasibility study of the micro-damage assessment of polymer bonded explosives by nonlinear ultrasonic technique in this work can be applied to damage identification, material degradation monitoring, and lifetime prediction of the explosive parts.

Paeoniflorin protects against lipopolysaccharide-induced acute lung injury in mice by alleviating inflammatory cell infiltration and microvascular permeability.

OBJECTIVE: The present study aims to explore the effects of paeoniflorin (PF), a monoterpene glycoside isolated from the roots of Paeonia lactiflora Pallas, on acute lung injury (ALI) and the possible mechanisms. MATERIALS AND METHOD: ALI was induced in mice by an intratracheal instillation of lipopolysaccharide (LPS, 1 mg/kg), and PF was injected intraperitoneally 30 min prior to LPS administration. After 24 h, lung water content, histology, microvascular permeability and proinflammatory cytokines in the bronchoaveolar lavage fluid were evaluated. RESULTS: It was shown that PF (50, 100 mg/kg) could alleviate LPS-induced ALI, evidenced by reduced pulmonary edema, improved histological changes, and attenuated inflammatory cell accumulation in the interstitium and alveolar space as well as microvascular permeability. It also markedly down-regulated the expressions of proinflammatory cytokines interleukin (IL)-1ß and tumor necrosis factor (TNF)-α at both transcription and protein levels. Additionally, PF inhibited the phosphorylations of p38 MAP kinase (p38) and c-Jun NH2-terminal kinase (JNK) but not extracellular signal-regulated kinase (ERK), and prevented the activation of nuclear factor-kappa B (NF-κB) in the lung tissues. CONCLUSION: The findings suggest that PF is able to alleviate ALI, and the underlying mechanisms are probably attributed to decreasing the production of proinflammatory cytokines through down-regulation of the activation of p38, JNK and NF-κB pathways in lung tissues.