Efficacy of bezlotoxumab in participants receiving metronidazole, vancomycin, or fidaxomicin for treatment of Clostridioides (Clostridium) difficile infection

Background: In phase 3 MODIFY I/II trials, bezlotoxumab significantly reduced recurrence of Methods: In MODIFY I/II (NCT01241552/NCT01513239), participants received a single infusion of bezlotoxumab (10 mg/kg) or placebo during anti-CDI treatment. Using pooled data from MODIFY I/II, initial clinical cure (ICC) and rCDI were assessed in metronidazole-, vancomycin-, and fidaxomicin-treated subgroups. Results: Of 1554 participants in MODIFY I/II, 753 (48.5%) received metronidazole, 745 (47.9%) vancomycin, and 56 (3.6%) fidaxomicin. Fewer participants receiving metronidazole had a prior CDI episode in the previous 6 months (12.9%) or ≥1 risk factor for rCDI (66.0%) vs participants receiving vancomycin (41.2% and 83.6%, respectively) and fidaxomicin (55.4% and 89.3%, respectively). ICC rates were similar in the bezlotoxumab (metronidazole, 81.0%; vancomycin, 78.5%; fidaxomicin, 86.7%) and placebo groups (metronidazole, 81.3%; vancomycin, 79.6%; fidaxomicin, 76.9%). In placebo-treated participants, the rCDI was lower in the metronidazole subgroup vs the vancomycin and fidaxomicin subgroups (metronidazole, 28.0%; vancomycin, 38.4%; fidaxomicin, 35.0%). When analyzed by subsets based on history of CDI, rCDI rates were similar in the metronidazole and vancomycin groups. rCDI rates were lower in all antibiotic subgroups for bezlotoxumab vs placebo (metronidazole: rate difference [RD], -9.7%; 95% confidence interval [CI], -16.4% to -3.1%; vancomycin: RD, -15.4%; 95% CI, -22.7% to -8.0%; fidaxomicin: RD, -11.9%; 95% CI, -38.1% to 14.3%). Conclusion: Bezlotoxumab reduces rCDI vs placebo in participants receiving metronidazole and vancomycin, with a similar effect size in participants receiving fidaxomicin

?2-Microglobulin Amyloid Fibril-Induced Membrane Disruption Is Enhanced by Endosomal Lipids and Acidic pH

Although the molecular mechanisms underlying the pathology of amyloidoses are not well understood, the interaction between amyloid proteins and cell membranes is thought to play a role in several amyloid diseases. Amyloid fibrils of ?2-microglobulin (?2m), associated with dialysis-related amyloidosis (DRA), have been shown to cause disruption of anionic lipid bilayers in vitro. However, the effect of lipid composition and the chemical environment in which ?2m-lipid interactions occur have not been investigated previously. Here we examine membrane damage resulting from the interaction of ?2m monomers and fibrils with lipid bilayers. Using dye release, tryptophan fluorescence quenching and fluorescence confocal microscopy assays we investigate the effect of anionic lipid composition and pH on the susceptibility of liposomes to fibril-induced membrane damage. We show that ?2m fibril-induced membrane disruption is modulated by anionic lipid composition and is enhanced by acidic pH. Most strikingly, the greatest degree of membrane disruption is observed for liposomes containing bis(monoacylglycero)phosphate (BMP) at acidic pH, conditions likely to reflect those encountered in the endocytic pathway. The results suggest that the interaction between ?2m fibrils and membranes of endosomal origin may play a role in the molecular mechanism of ?2m amyloid-associated osteoarticular tissue destruction in DRA

Amyloid fibres: inert end-stage aggregates or key players in disease?

The formation of amyloid fibres is a hallmark of amyloid disorders. Nevertheless, the lack of correlation between fibre load and disease as observed, for example, in Alzheimer's disease, means that fibres are considered secondary contributors to the onset of cellular dysfunction. Instead, soluble intermediates of amyloid assembly are often described as the agents of toxicity. Here, we discuss recent experimental discoveries which suggest that amyloid fibres should be considered as disease-relevant species that can mediate a range of pathological processes. These include disruption of biological membranes, secondary nucleation, amyloid aggregate transmission, and the disruption of protein homeostasis (proteostasis). Thus, a greater understanding of amyloid fibre biology could enhance prospects of developing therapeutic interventions against this devastating class of protein-misfolding disorders

Volcanic impacts on the Holocene vegetation history of Britain and Ireland? A review and meta-analysis of the pollen evidence

Volcanic ash layers show that the products of Icelandic volcanism reached Britain and Ireland many times during the Holocene. Historical records suggest that at least one eruption, that of Laki in a.d. 1783, was associated with impacts on vegetation. These results raise the question: did Icelandic volcanism affect the Holocene vegetation history of Britain and Ireland? Several studies have used pollen data to address this issue but no clear consensus has been reached. We re-analyse the palynological data using constrained ordination with various representations of potential volcanic impacts. We find that the palynological evidence for volcanic impacts on vegetation is weak but suggest that this is a case of absence of evidence and is not necessarily evidence of absence of impact. To increase the chances of identifying volcanic impacts, future studies need to maximise temporal resolution, replicate results, and investigate a greater number of tephras in a broader range of locations, including more studies from lake sediments

Aggregation modulators interfere with membrane interactions of beta2-microglobulin fibrils.

Amyloid fibril accumulation is a pathological hallmark of several devastating disorders, including Alzheimer's disease, prion diseases, type II diabetes, and others. Although the molecular factors responsible for amyloid pathologies have not been deciphered, interactions of misfolded proteins with cell membranes appear to play important roles in these disorders. Despite increasing evidence for the involvement of membranes in amyloid-mediated cytotoxicity, the pursuit for therapeutic strategies has focused on preventing self-assembly of the proteins comprising the amyloid plaques. Here we present an investigation of the impact of fibrillation modulators upon membrane interactions of ?2-microglobulin (?2m) fibrils. The experiments reveal that polyphenols (epigallocatechin gallate, bromophenol blue, and resveratrol) and glycosaminoglycans (heparin and heparin disaccharide) differentially affect membrane interactions of ?2m fibrils measured by dye-release experiments, fluorescence anisotropy of labeled lipid, and confocal and cryo-electron microscopies. Interestingly, whereas epigallocatechin gallate and heparin prevent membrane damage as judged by these assays, the other compounds tested had little, or no, effect. The results suggest a new dimension to the biological impact of fibrillation modulators that involves interference with membrane interactions of amyloid species, adding to contemporary strategies for combating amyloid diseases that focus on disruption or remodeling of amyloid aggregates

Confocal fluorescence microscopy of GUVs upon addition of fragmented β₂m fibrils.

<p>(<i>A</i>) Confocal images were collected in two different focal planes. The upper plane contains mainly non-vesicular lipid while dense, intact sucrose-loaded GUVs are observed mostly in the lower focal plane. Confocal images of TMR-labeled β₂m fragmented fibrils incubated with DiD-labeled GUVs for 15 min at ambient temperature in (<i>B</i>) <i>Assay Buffer</i> at pH 7.4 or (<i>C</i>) <i>Assay Buffer</i> at pH 6.5. <i>(L</i>-<i>R)</i> TMR-labeled β₂m fibrils (<i>red</i>), DiD-labeled GUVs (<i>green</i>), superimposition of the TMR and DiD channels. Soluble CF added to the vesicle exterior is shown in blue <i>(lower focal plane only</i>). Representative images when viewed in the upper focal plane and lower focal plane are shown for GUVs comprised of (<i>i</i>) 100 mol % DOPC or (ii) 80 mol % DOPC plus 20 mol % BMP. White arrows highlight areas of lipids bound to fibril aggregates. Scale bar 10 µm.</p

Variability of groundwater levels and total organic carbon in the riparian zone of a boreal catchment

The riparian zone is a narrow corridor where hillslopes (and their associated hydrobiogeochemical processes) interface with the river system. As such, the riparian zone serves as the last piece of landscape with which water interacts as it transitions from being water flowing primarily through the landscape (i.e., shallow groundwater) to water flowing primarily on the landscape (i.e., stream water). This study investigates the spatiotemporal variability in riparian-zone soil water total organic carbon (TOC) and its relation to the shallow groundwater table using observations from the recently instrumented riparian observatory in the Krycklan catchment study area located in boreal northern Sweden. In general, there is a decrease in TOC concentration with depth down through the soil profile. The rate of this decrease was variable among the six monthly samplings used in this study. The spatial variability of soil water TOC in the riparian zone was connected to the spatial variability of the shallow groundwater levels. This demonstrated the importance of the temporal variation of flow pathways and the mixing of waters from different sources of TOC moving into and through the riparian zone. The coupled variation of the hydrologic and biogeochemical systems raised questions about the ability of simple lumped approaches to accurately predict how in-stream TOC concentrations will change with climate and/or land use. The integrated sampling approach in the riparian observatory covers both hydrologic and biogeochemical aspects of soil water TOC and provides a basis for development and testing of distributed, physically based transport models

Dye release normalized to the change in tryptophan fluorescence quenching measured for β₂m with BMP-containing LUVs at pH 4.5.

<p>The ratio of % dye release per membrane interaction detected via a change in tryptophan quenching observed in the absence or presence of lipid. β₂m monomers, fragmented and unfragmented fibrils (6 µM monomer equivalent concentration) were incubated in <i>Assay Buffer</i> pH 4.5 with LUVs (5 µM lipid) comprising 36 POPC: 20 POPE: 7 SM: 25 cholesterol (mol/mol) plus 0 mol % (<i>blue</i>), 12 mol % (<i>red</i>) or 50 mol % (<i>green</i>) BMP for 10 min at 37°C. Error bar represent 1 S.E.</p

Change in tryptophan fluorescence quenching for β₂m in the presence of LUVs. Δ

<p><i>K_SV</i> for 6 µM monomer equivalent concentration β₂m monomer, fragmented or unfragmented fibrils 10 min after addition of LUVs (5 µM lipid) at 37°C in (<i>A</i>) <i>Assay buffer</i> at pH 7.4 or (<i>B</i>) <i>Assay buffer</i> at pH 4.5. Lipid mixes comprise 36 POPC: 20 POPE: 7 SM: 25 cholesterol (mol/mol) doped with 0 mol % (<i>blue</i>), 12 mol % (<i>red</i>) or 50 mol % (<i>green</i>) BMP. Error bars represent 1 S.E. from linear regression.</p

Lipid structures and characterization of β₂m fibrils using AFM.

<p>(<i>A</i>) Structure of anionic lipids, POPS, POPG and BMP. (<i>B</i>) Fibril length distributions and representative AFM images of (<i>i</i>) unfragmented (1.30±0.05 µm) and (<i>ii</i>) fragmented (0.30±0.01 µm) β₂m fibrils. Scale bar 1 µm.</p