Cyclic 100-ka (glacial-interglacial) migration of subseafloor redox zonation on the Peruvian shelf

The coupling of subseafloor microbial life to oceanographic and atmospheric conditions is poorly understood. We examined diagenetic imprints and lipid biomarkers of past subseafloor microbial activity to evaluate its response to glacial-interglacial cycles in a sedimentary section drilled on the Peruvian shelf (Ocean Drilling Program Leg 201, Site 1229). Multiple and distinct layers of diagenetic barite and dolomite, i.e., minerals that typically form at the sulfate−methane transition (SMT), occur at much shallower burial depth than the present SMT around 30 meters below seafloor. These shallow layers co-occur with peaks of ¹³C-depleted archaeol, a molecular fossil of anaerobic methane-oxidizing Archaea. Present-day, non-steady state distributions of dissolved sulfate also suggest that the SMT is highly sensitive to variations in organic carbon flux to the surface shelf sediments that may lead to shoaling of the SMT. Reaction-transport modeling substantiates our hypothesis that shallow SMTs occur in response to cyclic sediment deposition with a high organic carbon flux during interglacials and a low organic carbon flux during glacial stages. Long diffusion distances expectedly dampen the response of deeply buried microbial communities to changes in sediment deposition and other oceanographic drivers over relatively short geological time scales, e.g., glacial-interglacial periods. However, our study demonstrates how dynamically sediment biogeochemistry of the Peru Margin has responded to glacial-interglacial change and how these changes are now preserved in the geological record. Such changes in subsurface biogeochemical zonation need to be taken into account to assess the role of the subseafloor biosphere in global element and redox cycling.Microbial life beneath the ocean reacts to and alters the organic matter and sediment deposited on the seafloor and buried over geological time scales of millennia or more. This subseafloor biosphere mineralizes buried organic matter, changes the geochemical gradients, and affects the precipitation or dissolution of minerals (1–3). Discrete zones of microbial abundance and activity develop (4–7) where sulfate (SO₄²⁻) diffusing downward from the overlying seawater intersects with upward diffusing methane (CH₄). Here the anaerobic oxidation of methane (AOM) is coupled to sulfate reduction (5, 8), and both compounds become depleted in this sulfate methane transition (SMT). The SMT is typically located within the top few meters to tens of meters below seafloor in continental shelf and slope sediments. Under steady state conditions, i.e., when the rates of both organic and bulk sedimentation remain constant and the quality of the deposited organic matter is uniform over time, no significant change occurs in the fluxes of dissolved methane and sulfate, and the SMT remains at a constant depth beneath the seafloor (8, 9). Sedimentation and organic carbon flux, however, are seldom constant over time. Especially at ocean margins where the organic matter flux to the seafloor is large and variable, oceanographic changes may result in a strong response of subseafloor methane and sulfate gradients. For example, high sedimentation rates and high organic carbon fluxes lead to high microbial activity and, over time, to a shallow SMT (10). A lowered deposition rate of organic matter will reduce microbial activity and cause a downward migration of the SMT.The SMT depth is therefore controlled by past environmental changes that affect the rate of sediment deposition and burial and, thus, affect the amount and quality of organic matter that today serves as substrate for microbial processes in the subsurface (11). Pore water analyses and microbiological studies provide information on the current metabolic processes (5–7), but the factors controlling the SMT depth over geological time are not well constrained.Changes in the depth of the SMT as a result of variations in the flux of methane and sulfate leave diagenetic imprints, such as iron sulfides, barium sulfate (barite) or calcium carbonates (3, 9, 12, 13), and anomalous, non-steady state distributions in pore water chemistry (3, 9, 14). Carbon isotope signatures in diagenetic dolomites from a sedimentary sequence recovered from the Peru Margin suggested that biogeochemical conditions at the SMT are subject to strong variations over time (15). Regularly spaced diagenetic dolomite layers were interpreted as a consequence of periodic upward and downward migration of the SMT triggered by glacial-interglacial variation in sediment deposition (16). However, the mechanisms that drive the upward or downward shifts of the SMT and lead to episodic precipitation of diagenetic minerals remained unclear.We present here a high-resolution record of geochemical signatures indicative of the past location of the SMT from a sedimentary sequence drilled at Ocean Drilling Program (ODP) Site 1229 at 150 m water depth on the Peruvian continental shelf (10°59′ S, 77°57′ W; Fig. S1). We scanned entire core sections at high resolution (1 cm) using an X-ray fluorescence (XRF) scanner to screen for focused element enrichments indicative of diagenetic mineral phases, such as barite and authigenic carbonates. Total organic carbon (TOC) and lipid biomarkers indicative of microbial communities at the SMT were analyzed with a depth resolution of 20 cm (5 cm in the uppermost 5 m) and compound-specific isotopic compositions of the lipids were measured at selected depths. Based on the diagenetic and molecular fossil imprints, we identify past locations of the SMT in the subseafloor and reconstruct its migration history. To test the feasibility and to understand potential geochemical controls on an upward or downward migrating SMT, the SMT depth was simulated as a function of variable sedimentation rate and organic matter influx using a transient reactive transport model. Our results reveal how dynamically the deep biosphere reacts to changes in sediment input at the seafloor and, hence, how changes in oceanographic conditions at geological timescales may influence microbial life below the seafloor.     

Cutting to the chase: Participation factors,behavioral effects,and cultural perspectives of participants in an adult circumcision campaign

Following the adoption of key national policy, several campaigns aimed at increasing the number of adult males receiving circumcisions have been implemented across South Africa. Evidence as to the likely effectiveness of such interventions comes predominantly from three large randomized-controlled trials. However, little has been written about how these campaigns are perceived by the participants. This is significant given the importance of the social issues that are implicit in determining both the ethical acceptability, and effectiveness of these campaigns. We report on a study aimed at identifying and exploring motivating factors for participation, behavioral effects, and cultural attitudes of participants towards a circumcision campaign undertaken in the Northern Cape Province. For this interpretive sociological research project, semi-structured interviews were conducted with 29 participants. These were recorded, transcribed, and qualitatively analyzed. The main reasons given for participation included that of reducing the risk of acquiring HIV and other sexually transmitted infections (STIs), as well as the enhancement of sexual experience. Participants insisted that they would continue to use condoms after the circumcision, although felt that other community members receiving circumcisions would not do so. Several advantages were described when receiving a circumcision at a public health facility, as opposed to the manner more traditional to the participant's culture. Whilst they did not report intentions for risk compensation, the reasons given for participation and their willingness to attribute this problem to other community members casts doubt on the veracity of their reported intentions. Furthermore, participants did not appear to have a complete understanding as to how circumcision is protective. Participants shared the belief that circumcisions as performed in the context of this campaign were safer than the traditional circumcision occurring in the area, which represents an important area for further research.     

Current Advances,Research Needs and Gaps in Mycotoxins Biomonitoring under the HBM4EU—Lessons Learned and Future Trends

Mycotoxins are natural metabolites produced by fungi that contaminate food and feed worldwide. They can pose a threat to human and animal health, mainly causing chronic effects, e.g., immunotoxic and carcinogenic. Due to climate change, an increase in European population exposure to mycotoxins is expected to occur, raising public health concerns. This urges us to assess the current human exposure to mycotoxins in Europe to allow monitoring exposure and prevent future health impacts. The mycotoxins deoxynivalenol (DON) and fumonisin B₁ (FB₁) were considered as priority substances to be studied within the European Human Biomonitoring Initiative (HBM4EU) to generate knowledge on internal exposure and their potential health impacts. Several policy questions were addressed concerning hazard characterization, exposure and risk assessment. The present article presents the current advances attained under the HBM4EU, research needs and gaps. Overall, the knowledge on the European population risk from exposure to DON was improved by using new harmonised data and a newly derived reference value. In addition, mechanistic information on FB₁ was, for the first time, organized into an adverse outcome pathway for a congenital anomaly. It is expected that this knowledge will support policy making and contribute to driving new Human Biomonitoring (HBM) studies on mycotoxin exposure in Europe.     

Correction to: Diagnostic performance of four SARS-CoV-2 antibody assays in patients with COVID-19 or with bacterial and non-SARS-CoV-2 viral respiratory infections

European Journal of Clinical Microbiology & Infectious Diseases -     

Gel Point Determination in Resin Transfer Molding Process with Fiber Bragg Grating Inscribed in Side-Hole Elliptical Core Optical Fiber

Material as well as process variations in the composites industry are reasons to develop methods for in-line monitoring, which would increase reproducibility of the manufacturing process and the final composite products. Fiber Bragg Gratings (FBGs) have shown to be useful for monitoring liquid-composite molding processes, e.g., in terms of online gel point detection. Existing works however, focus on in-plane strain measurements while out-of-plane residual strain prevails. In order to measure out-of-plane strain, FBG inscribed in highly birefringent fiber (HB FBG) can be used. The purpose of this research is the cure stage detection with (a) FBG inscribed in single mode and (b) FBG inscribed in highly-birefringent side-hole fiber in comparison to the reference gel point detected with an in-mold DC sensor. Results reveal that the curing process is better traceable with HB FBG than with regular FBG. Thus, the use of HB FBG can be a good method for the gel point estimation in the RTM process.     

Successful rescue with leucovorin and thymidine in a patient with high-dose methotrexate induced acute renal failure

A 54-year-old patient with primary cerebral lymphoma was treated with two 4-weekly cycles of high-dose intravenous cytarabine (12 g/m2) and methotrexate (3 g/m2). The administration of the first course proceeded without notable complications. Before the administration of methotrexate in the second cycle blood cell counts and chemistry showed no abnormalities except for slightly increased alkaline phosphatase and gamma-glutamyl-transpeptidase levels which was attributed to diphantoin comedication. The patient developed symptoms of acute renal failure 7 h after methotrexate infusion which resulted in a very high serum methotrexate level (39.84 micromol/l) at 20 h after infusion. Rescue therapy was intensified: the leucovorin dosage was increased (1,200 mg continuous i.v. infusion every 24 h) and combined with thymidine rescue therapy (8 g/m2 per day continuous i.v. infusion every 24 h). Urine alkalinization was increased and diphantoin therapy was stopped. Leucovorin eye drops and mouth washes were started 5 days after methotrexate administration to prevent conjunctivitis and mucositis as a result of high methotrexate levels (>2.4 micromol/l). In spite of the fact that serum methotrexate levels remained persistently higher than 0.1 micromol/l for 12 days, the patient experienced no further short-term systemic toxicity except for anaemia (grade 3 according to NCI Common Toxicity Criteria). After day 12 intensified rescue therapy and the frequency of alkalinization were decreased to standard procedures and stopped on day 19. It is concluded that i.v. administration with high-dose methotrexate can result in unpredictable acute toxicity. In our patient, acute methotrexate toxicity was treated successfully by intensification of classical leucovorin rescue therapy in combination with thymidine infusion. In addition, leucovorin mouth washes and eye drops may have prevented mucositis and conjunctivitis, respectively.