Influence of hydrogen on the reductive dechlorination of tetrachloroethene to ethene in a biofilm reactor: role of mass transport phenomena

This study investigated the influence of H2 bulk liquid concentration in the range 2-120 μmol L-1 on the kinetics of vinyl chloride (VC) formation from tetrachloroethene (PCE) and VC dechlorination to ethene in a methanogenic biofilm reactor containing Dehalococcoides spp. as the putative dechlorinating microorganism. Both VC formation and dechlorination showed a definite increase in rate with increasing H2 bulk liquid concentration, following a pattern typical of Michaelis-Menten kinetics. The estimated maximum VC formation rate (81.7 ± 9.4 μmol L-1 h-1 mean value ± 90% confidence interval) was about ten times higher than the estimated maximum VC dechlorination rate (8.2 ± 1.0 μmol L-1 h-1), while the estimated apparent half-velocity coefficient for H2 for VC formation (1.5 ± 1.4 μmol H2 L-1) was more than six times lower than that for VC dechlorination (9.1 ± 5.1 μmol H2 L-1), confirming that the last step of PCE dechlorination (i.e. conversion of VC to ethene) was much more H2-sensitive than the previous ones. The estimated maximum methane formation rate was 462.1 ± 213.5 μmol L-1 h-1 and the estimated apparent half-velocity coefficient was 104.7 ± 89.4 μmol H2 L-1. Experiments at different temperatures indicated the presence of severe internal (diffusional) mass transfer limitations and, in turn, of steep H2 concentration gradients through the biofilm, which strongly influenced the estimated apparent half-velocity coefficients for H2 use. The results of this study emphasise the importance of considering mass transfer phenomena when predicting the rate of PCE dechlorination and the outcome of competition for H2 in natural or engineered bioremediation systems

MACULAR PUCKER: To Peel or Not to Peel the Internal Limiting Membrane? A Microperimetric Response

To compare functional and anatomical outcomes after idiopathic macular pucker removal between eyes that underwent internal limiting membrane (ILM) peeling and eyes that did not.In this multicentric, randomized clinical trial, 60 eyes of 60 patients affected with idiopathic macular pucker were enrolled. Thirty eyes underwent 23-gauge pars plana vitrectomy associated with ILM peeling ("ILM peeling group"), whereas 30 eyes did not undergo ILM peeling ("ILM not peeling group"). Retinal sensitivity, frequency of microscotomas, and all the other microperimetric parameters were tested by MP1 microperimetry. Best-corrected visual acuity was investigated with the Early Treatment Diabetic Retinopathy Study chart. Anatomical outcomes were analyzed with spectral domain optical coherence tomography.After a 12-month follow-up, the mean retinal sensitivity in the 4° central area showed a greater and faster recovery in the ILM not peeling group than in the ILM peeling group (P = 0.041). The number of absolute microscotomas (0 dB) within the 12° central retinal area was significantly higher in the ILM peeling group than in the ILM not peeling group (P = 0.044).The ILM not peeling group seems to show better outcomes than the ILM peeling group as measured by mean retinal sensitivity and number of microscotomas after a 12-month follow-up

Acid-free glyoxal as a substitute of formalin for structural and molecular preservation in tissue samples

<div><p>Tissue fixation in phosphate buffered formalin (PBF) remains the standard procedure in histopathology, since it results in an optimal structural, antigenic and molecular preservation that justifies the pivotal role presently played by diagnoses on PBF-fixed tissues in precision medicine. However, toxicity of formaldehyde causes an environmental concern and may demand substitution of this reagent. Having observed that the reported drawbacks of commercially available glyoxal substitutes of PBF (Prefer, Glyo-fix, Histo-Fix, Histo-CHOICE, and Safe-Fix II) are likely related to their acidity, we have devised a neutral fixative, obtained by removing acids from the dialdehyde glyoxal with an ion-exchange resin. The resulting glyoxal acid-free (GAF) fixative has been tested in a cohort of 30 specimens including colon (N = 25) and stomach (N = 5) cancers. Our results show that GAF fixation produces a tissue and cellular preservation similar to that produced by PBF. Comparable immuno-histochemical and molecular (DNA and RNA) analytical data were obtained. We observed a significant enrichment of longer DNA fragment size in GAF-fixed compared to PBF-fixed samples. Adoption of GAF as a non-toxic histological fixative of choice would require a process of validation, but the present data suggest that it represents a reliable candidate.</p></div

Analysis of Functional Dissociations between Best Corrected Visual Acuity and Microperimetric Parameters in Neovascular Age-Related Macular Degeneration Patients Underwent to Three Monthly Ranibizumab Injections

Background: To analyze the sensitivity of best corrected visual acuity and microperimetry to detect significant visual changes after 3 intravitreal ranibizumab in exudative age-related macular degeneration. Design: Prospective, open-label study. Participants: 50 eyes of 50 naïve patients affected by neovascular age-related macular degeneration were enrolled. Methods: Enrolled patients underwent to a loading phase of 3 monthly intravitreal injections of ranibizumab. Best-corrected visual acuity was investigated with the ETDRS chart at 4 m. Central retinal sensitivity was tested with microperimetry using a Goldmann III stimulus to 33 points over the 12° central of the macula with a 4-2 double staircase strategy. Main outcome measures: Comparison of changes in mean 4° central retinal sensitivity and best-corrected visual acuity in “BCVA relatively stable patients” (defined as change ≤ ± 4 ETDRS letters after treatment). Analysis of a possible relationship between changes in best-corrected visual acuity and 4° central retinal sensitivity in “mean 4° central retinal sensitivity relatively stable patients” (defined as change in mean retinal sensitivity ≤ ± 2dB) Results: Mean best-corrected visual acuity improved of 5.90 ± 11.29 ETDRS letters (P=0.0006). Total mean retinal sensitivity improved +1.59 ± 2.12 dB (P<0.0001), while in the 4° central retinal area the increase was +1.36 ± 3.45 dB (P=0.0078). 38% of patients (19 eyes) were considered as “BCVA relatively stable patients”. In this subgroup, Pearson’s correlation analysis showed a direct correlation between changes observed with both methods (r = 0.71; P = 0.002). 48% of patients (24 eyes) were considered as “Mean 4° central retinal sensitivity relatively stable patients”. In this subgroup, Pearson’s correlation analysis didn’t show a relationship between changes observed with both methods (r = 0.11; P = 0.56). Conclusions: Microperimetry central retinal sensitivity seems to be an important to complete the functional evaluation in patients with wet age-related macular degeneration after 3 intravitreal ranibizumab

Intravitreal ranibizumab for predominantly hemorrhagic choroidal neovascularization in age-related macular degeneration

Purpose: To evaluate the effects of intravitreal ranibizumab monotherapy on predominantly hemorrhagic choroidal neovascularization with foveal involvement associated with age-related macular degeneration. Materials and Methods: Twenty-two consecutive eyes with hemorrhagic neovascularization were treated with 3 monthly intravitreal ranibizumab injections. Additional injections were administered according to retreatment criteria during 12 months of follow-up. Results: A mean of 6.64 ± 1.36 injections was administered. Overall, the mean visual acuity increased from 10.90 ± 6.02 to 12.81 ± 8.34 ETDRS letters (p > 0.05) at 12 months. The 'early treatment group' gained a mean of 2.83 ± 2.24 ETDRS letters (p 0.05) with significant differences between the groups (p < 0.05). A progressive resolution of macular bleeding was registered in 20 patients (mean time: 5.3 ± 1.6 months). Conclusions: Ranibizumab injections can be considered a beneficial approach for the management of predominantly hemorrhagic choroidal neovascularization with foveal involvement associated with age-related macular degeneration. Furthermore, the time interval between hemorrhage and the first injection seems to be an important predicting factor of final visual acuity