Geobacter sulfurreducens inner membrane cytochrome CbcBA controls electron transfer and growth yield near the energetic limit of respiration.

Geobacter sulfurreducens utilizes extracellular electron acceptors such as Mn(IV), Fe(III), syntrophic partners, and electrodes that vary from +0.4 to -0.3 V versus standard hydrogen electrode (SHE), representing a potential energy span that should require a highly branched electron transfer chain. Here we describe CbcBA, a bc-type cytochrome essential near the thermodynamic limit of respiration when acetate is the electron donor. Mutants-lacking cbcBA ceased Fe(III) reduction at -0.21 V versus SHE, could not transfer electrons to electrodes between -0.21 and -0.28 V, and could not reduce the final 10%-35% of Fe(III) minerals. As redox potential decreased during Fe(III) reduction, cbcBA was induced with the aid of the regulator BccR to become one of the most highly expressed genes in G. sulfurreducens. Growth yield (CFU/mM Fe(II)) was 112% of WT in ∆cbcBA, and deletion of cbcL (an unrelated bc-cytochrome essential near -0.15 V) in ΔcbcBA increased yield to 220%. Together with ImcH, which is required at high redox potentials, CbcBA represents a third cytoplasmic membrane oxidoreductase in G. sulfurreducens. This expanding list shows how metal-reducing bacteria may constantly sense redox potential to adjust growth efficiency in changing environments.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY IN ADULT-ONSET FOVEOMACULAR VITELLIFORM DYSTROPHY.

PURPOSE: To determine the ability of optical coherence tomography angiography (OCTA) to detect choroidal neovascularization (CNV) in the pseudohypopyon stage of adult-onset foveomacular vitelliform dystrophy. METHODS: Prospective case series of eight consecutive patients with adult-onset foveomacular vitelliform dystrophy with at least one eye in the pseudohypopyon stage (a total of 14 eyes). Patients were assessed with spectral domain OCT, flourescein angiography, and OCTA. Main outcome measures were the presence or absence of CNV and any unifying patterns that could be identified on OCTA for adult-onset foveomacular vitelliform dystrophy. RESULTS: One (12.5%) of eight eyes in the pseudohypopyon stage had CNV on OCTA, without definitive evidence of CNV on flourescein angiography. Twelve of 14 eyes (86%) had OCTA segmentation errors, giving the false appearance of deep capillary plexus drop out. All 14 eyes (100%) had blockage of flow signal under the vitelliform lesion on OCTA that presented as artifactual loss of flow in the choriocapillaris. CONCLUSION: Optical coherence tomography angiography may be superior to flourescein angiography in detecting CNV in adult-onset foveomacular vitelliform dystrophy, especially in the pseudohypopyon stage. There are common artifacts that must be considered when analyzing vitelliform lesions with OCTA, including segmentation errors and inability to visualize flow under the vitelliform lesion in the choriocapillaris.

Microplastic contamination in filter-feeding oyster Saccostrea cuccullata: Novel insights in a marine ecosystem.

Microplastic (MP) pollution has become a pressing global concern. Oysters are well-known filter feeders who ingest food by filtering microscopic particles suspended in the surrounding water. Along with organic matter, filter-feeding also causes accidental ingestion of MP by oysters. Hence, the aim of the current investigation is to understand the MP contamination in filter-feeding oysters. A total of 500 specimens of oyster Saccostrea cuccullata collected from the intertidal zone of five sampling locations on the Gujarat coast, India. Specimens underwent analysis following established protocols. Each specimen was found to exhibit MP contamination, showing an abundance of 2.72 ± 1.98 MPs/g. A negative relationship was found between shell length and MP abundance. Predominantly, fibers were documented across all study sites. Black, blue, and red-colored MPs with 1-2 mm sizes were most dominant. MP polymer composition was identified as polyethylene terephthalate and polypropylene. Findings provide baseline information on levels of MPs contamination, which can be used to monitor future effects of MP pollution.

Design of a microbial fuel cell and its transition to microbial electrolytic cell for hydrogen production by electrohydrogenesis.

Anaerobic bacteria were isolated from industrial wastewater and soil samples and tested for exoelectrogenic activity by current production in double chambered microbial fuel cell (MFC), which was further transitioned into a single chambered microbial electrolytic cell to test hydrogen production by electrohydrogenesis. Of all the cultures, the isolate from industrial water sample showed the maximum values for current = 0.161 mA, current density = 108.57 mA/m2 and power density = 48.85 mW/m2 with graphite electrode. Maximum voltage across the cell, however, was reported by the isolate from sewage water sample (506 mv) with copper as electrode. Tap water with KMnO4 was the best cathodic electrolyte as the highest values for all the measured MFC parameters were reported with it. Once the exoelectrogenic activity of the isolates was confirmed by current production, these were tested for hydrogen production in a single chambered microbial electrolytic cell (MEC) modified from the MFC. Hydrogen production was reported positive from co-culture of isolates of both the water samples and co-culture of one soil and one water sample. The maximum rate and yield of hydrogen production was 0.18 m3H2/m3/d and 3.2 mol H2/mol glucose respectively with total hydrogen production of 42.4 mL and energy recovery of 57.4%. Cumulative hydrogen production for a five day cycle of MEC operation was 0.16 m3H2/m3/d.

Cryo-EM structure of an extracellular Geobacter OmcE cytochrome filament reveals tetrahaem packing.

Electrically conductive appendages from the anaerobic bacterium Geobacter sulfurreducens were first observed two decades ago, with genetic and biochemical data suggesting that conductive fibres were type IV pili. Recently, an extracellular conductive filament of G. sulfurreducens was found to contain polymerized c-type cytochrome OmcS subunits, not pilin subunits. Here we report that G. sulfurreducens also produces a second, thinner appendage comprised of cytochrome OmcE subunits and solve its structure using cryo-electron microscopy at ~4.3 Å resolution. Although OmcE and OmcS subunits have no overall sequence or structural similarities, upon polymerization both form filaments that share a conserved haem packing arrangement in which haems are coordinated by histidines in adjacent subunits. Unlike OmcS filaments, OmcE filaments are highly glycosylated. In extracellular fractions from G. sulfurreducens, we detected type IV pili comprising PilA-N and -C chains, along with abundant B-DNA. OmcE is the second cytochrome filament to be characterized using structural and biophysical methods. We propose that there is a broad class of conductive bacterial appendages with conserved haem packing (rather than sequence homology) that enable long-distance electron transport to chemicals or other microbial cells.

Melanoma knowledge, perception, and awareness in ethnic minorities in Chicago: recommendations regarding education.

OBJECTIVES: To assess the level of melanoma awareness and risk perception among ethnic minorities and to identify ways to enhance the relevance of melanoma educational materials for ethnic minorities. METHODS: Twelve focus groups composed of participants from a single ethnicity [African-American (n=40), Hispanic (n=40), and Asian (n=40)], participated in a 2 h discussion on melanoma and skin cancer and commented on an educational brochure by the American Cancer Society and reacted to photographs of melanoma on ethnic skin. Participants also evaluated the ability to sunburn and tan and the skin cancer risk of images of celebrities before and after the discussion. Additionally, participants assessed the skin tone of celebrities as very fair, fair, olive, light brown, dark brown, and very dark. The audiotape recordings of the 12 focus groups were transcribed and analyzed with the Non-numerical Unstructured Data Indexing Searching and Theorizing software for common themes. RESULTS: The common themes were (1) lack of relevance of skin cancer to ethnic people, (2) understanding of skin cancer risk terminology is based on personal experience and what is acquired from the media, and (3) sources of health information for ethnic minorities are fragmented and physicians are not the primary source of information. Celebrity images representing the six skin tones were selected. CONCLUSIONS: Relevance of melanoma education to ethnic people may be improved by using 'melanoma skin cancer', photographs of early melanoma in people with dark skin, and providing guidance on how to inspect hands and feet for suspicious moles.

Prophylactic antibiotic use after intravitreal injection: effect on endophthalmitis rate.

PURPOSE: Endophthalmitis after intravitreal injection is a serious complication. There are limited data to support the use of postinjection antibiotics to prevent endophthalmitis. Current endophthalmitis rates after intravitreal injection in the literature are based on studies where patients routinely received postinjection antibiotics. This study retrospectively compares the rate of endophthalmitis in a cohort of patients receiving postinjection antibiotics with that in a group that does not. METHODS: A retrospective chart review was performed comparing a 12-month period where patients received postinjection topical antibiotics for several days after intravitreal injection with the next 12-month period where no postinjection topical antibiotics were used. Cases of suspected endophthalmitis after intravitreal injection during this period were identified and reviewed. RESULTS: The rate of clinically suspected endophthalmitis in the cohort of patients receiving postinjection antibiotics after intravitreal injection and that in the cohort that did not was 0.22% and 0.20%, respectively. One culture-positive case was found overall. The difference between the 2 groups is not statistically significant (P = 0.75). CONCLUSION: The rate of endophthalmitis after intravitreal injections administered in a clinical practice setting when aseptic technique is used is similar with or without the use of postinjection antibiotics.

Gnidia glauca- and Plumbago zeylanica-Mediated Synthesis of Novel Copper Nanoparticles as Promising Antidiabetic Agents.

Rapid, eco-friendly, and cost-effective one-pot synthesis of copper nanoparticles is reported here using medicinal plants like Gnidia glauca and Plumbago zeylanica. Aqueous extracts of flower, leaf, and stem of G. glauca and leaves of P. zeylanica were prepared which could effectively reduce Cu2+ ions to CuNPs within 5 h at 100°C which were further characterized using UV-visible spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive spectroscopy, dynamic light scattering, X-ray diffraction, and Fourier-transform infrared spectroscopy. Further, the CuNPs were checked for antidiabetic activity using porcine pancreatic α-amylase and α-glucosidase inhibition followed by evaluation of mechanism using circular dichroism spectroscopy. CuNPs were found to be predominantly spherical in nature with a diameter ranging from 1 to 5 nm. The phenolics and flavonoids in the extracts might play a critical role in the synthesis and stabilization process. Significant change in the peak at ∼1095 cm-1 corresponding to C-O-C bond in ether was observed. CuNPs could inhibit porcine pancreatic α-amylase up to 30% to 50%, while they exhibited a more significant inhibition of α-glucosidase from 70% to 88%. The mechanism of enzyme inhibition was attributed due to the conformational change owing to drastic alteration of secondary structure by CuNPs. This is the first study of its kind that provides a strong scientific rationale that phytogenic CuNPs synthesized using G. glauca and P. zeylanica can be considered to develop candidate antidiabetic nanomedicine.

Role of the antioxidant system in the regulation of the chlorophyll biosynthesis pathway in the vascular plant Cucumis sativus.

In this study, the role of the antioxidant system has been examined in the regulation of the chlorophyll biosynthesis pathway in the vascular plant Cucumis sativus L. To generate reactive oxygen species (ROS), etiolated (E) and green (G) cucumber cotyledons were treated with methyl viologen (MV) or were exposed to high light (HL, 400-500µEm-2s-1). ROS generation was confirmed by measuring proline and H2O2 concentrations. With the effects of the MV- and HL-induced oxidative stress, it was observed that the chlorophyll biosynthesis pathway was severely affected in the HL-treated etiolated cotyledons (E-HL), MV-treated etiolated cotyledons (E-MV) and in MV-treated green cotyledons (G-MV) at 5-amino levulinic acid (ALA) as well as at protoporphyrin IX and Mg-protoporphyrin IX monomethyl ester levels. The antioxidant assays conducted showed that the ascorbate peroxidase (APX) activity had decreased in the E-HL, E-MV and G-MV cotyledons along with the levels of ascorbate and lutein. A decrease in the NADPH-dependent thioredoxin reductase (NTRC) was also observed in the MV-treated cotyledons with a significant impairment of the catalase activity in the E-HL cotyledons. Conversely, in the HL-treated green i.e. G-HL cotyledons, where the accumulation of H2O2 and the inhibition of chlorophyll biosynthesis were not observed, an increase in the levels of APX, NTRC, peroxiredoxin, ascorbate, glutathione and lutein was noted. Thus, the results obtained suggested that the antioxidant system could influence the flow of the chlorophyll biosynthesis pathway through maintaining the levels of H2O2.

Gloriosa superba Mediated Synthesis of Platinum and Palladium Nanoparticles for Induction of Apoptosis in Breast Cancer.

Green chemistry approaches for designing therapeutically significant nanomedicine have gained considerable attention in the past decade. Herein, we report for the first time on anticancer potential of phytogenic platinum nanoparticles (PtNPs) and palladium nanoparticles (PdNPs) using a medicinal plant Gloriosa superba tuber extract (GSTE). The synthesis of the nanoparticles was completed within 5 hours at 100°C which was confirmed by development of dark brown and black colour for PtNPs and PdNPs, respectively, along with enhancement of the peak intensity in the UV-visible spectra. High-resolution transmission electron microscopy (HRTEM) showed that the monodispersed spherical nanoparticles were within a size range below 10 nm. Energy dispersive spectra (EDS) confirmed the elemental composition, while dynamic light scattering (DLS) helped to evaluate the hydrodynamic size of the particles. Anticancer activity against MCF-7 (human breast adenocarcinoma) cell lines was evaluated using MTT assay, flow cytometry, and confocal microscopy. PtNPs and PdNPs showed 49.65 ± 1.99% and 36.26 ± 0.91% of anticancer activity. Induction of apoptosis was most predominant in the underlying mechanism which was rationalized by externalization of phosphatidyl serine and membrane blebbing. These findings support the efficiency of phytogenic fabrication of nanoscale platinum and palladium drugs for management and therapy against breast cancer.

Amiodarone: A potential risk factor for retinal phototoxicity.

PURPOSE: To report the only known case, to our knowledge, of amiodarone induced retinal phototoxicity following vitrectomy surgery. OBSERVATIONS: A 66-year-old male presented with visual acuity of 20/150 OS secondary to an epiretinal membrane (ERM). Patient was on oral amiodarone for atrial fibrillation. Baseline spectral domain optical coherence tomography (SD-OCT) revealed an ERM with retinal thickening and schisis. The patient underwent an uncomplicated pars plana vitrectomy and membrane peel using standard vitrectomy settings and illumination. Triamcinolone was used to stain the ERM intraoperatively. ICG was not used. On post-operative day one, vision was count finger (CF) at 1'. At post-operative week one, vision was unchanged and SD-OCT showed macular edema. At post-operative month one, vision remained CF at 1' and macular edema resolved with residual pigmentary changes and subretinal fibrosis resembling phototoxic damage. SD-OCT at one month showed resolution of macular edema, retinal pigment epithelium hyperplasia and an indistinct ellipsoid layer. Fluorescein angiography did not show any neovascularization. At three month follow-up, patient's vision, exam and OCT findings remained unchanged. CONCLUSIONS AND IMPORTANCE: Many pharmacologic agents have the ability to alter a patient's sensitivity to solar or artificial radiation. Drugs act as photosensitizers that lead to photochemical damage. Amiodarone has been reported to have such photosensitizing properties in humans. This report describes a case of retinal phototoxicity from intraoperative light exposure photosensitized by systemic amiodarone use.

Chorioretinal Lesions in a Case of Melanoma-Associated Retinopathy Treated With Pembrolizumab.

IMPORTANCE: In recent years, the treatment of patients with advanced cutaneous melanoma has undergone substantial changes. Patients can now be offered treatment with immune checkpoint inhibitors, which are capable of increasing patient survival. However, these new treatments are associated with immune-related adverse effects that can involve different organ systems, including the eye. OBSERVATIONS: We describe the case of a patient who received a diagnosis of metastatic cutaneous melanoma and developed melanoma-associated retinopathy with unanticipated fundus findings while receiving treatment with the immune checkpoint inhibitor pembrolizumab. Chorioretinal scars with pigment accumulations developed in the retinal periphery in both eyes. CONCLUSIONS AND RELEVANCE: Immune checkpoint inhibitors, which are now being used more commonly for patients with advanced stages of melanoma, can exacerbate autoimmune diseases in patients with underlying clinical or latent autoimmunity. Clinicians should be aware of atypical eye findings, including chorioretinal scars.

Symmetrical peripheral gangrene with Plasmodium falciparum malaria.

Symmetric peripheral gangrene is rare and relatively uncommon complication of malaria. We report a case of a 50-year-old male who survived Plasmodium falciparum infection with disseminated intravascular coagulation. Symmetric peripheral gangrene in our case, which ultimately required amputation of the toes, was most likely due to interaction between parasitic factors and host factors.