Search

Deep learning (DL) shows notable success in biomedical studies. However, most DL algorithms work as black boxes, exclude biomedical experts, and need extensive data. This is especially problematic for fundamental research in the laboratory, where often only small and sparse data are available and the objective is knowledge discovery rather than automation. Furthermore, basic research is usually hypothesis‐driven and extensive prior knowledge (priors) exists. To address this, the Self‐Enhancing Multi‐Photon Artificial Intelligence (SEMPAI) that is designed for multiphoton microscopy (MPM)‐based laboratory research is presented. It utilizes meta‐learning to optimize prior (and hypothesis) integration, data representation, and neural network architecture simultaneously. By this, the method allows hypothesis testing with DL and provides interpretable feedback about the origin of biological information in 3D images. SEMPAI performs multi‐task learning of several related tasks to enable prediction for small datasets. SEMPAI is applied on an extensive MPM database of single muscle fibers from a decade of experiments, resulting in the largest joint analysis of pathologies and function for single muscle fibers to date. It outperforms state‐of‐the‐art biomarkers in six of seven prediction tasks, including those with scarce data. SEMPAI's DL models with integrated priors are superior to those without priors and to prior‐only approaches. [ABSTRACT FROM AUTHOR]

Optoacoustic imaging (OAI) enables microscale imaging of endogenous chromophores such as hemoglobin at significantly higher penetration depths compared to other optical imaging technologies. Raster‐scanning optoacoustic mesoscopy (RSOM) has recently been shown to identify superficial microvascular changes associated with human skin pathologies. In animal models, the imaging depth afforded by RSOM can enable entirely new capabilities for noninvasive imaging of vascular structures in the gastrointestinal tract, but exact localization of intra‐abdominal organs is still elusive. Herein the development and application of a novel transrectal absorber guide for RSOM (TAG‐RSOM) is presented to enable accurate transabdominal localization and assessment of colonic vascular networks in vivo. The potential of TAG‐RSOM is demonstrated through application during mild and severe acute colitis in mice. TAG‐RSOM enables visualization of transmural vascular networks, with changes in colon wall thickness, blood volume, and OAI signal intensities corresponding to colitis‐associated inflammatory changes. These findings suggest TAG‐RSOM can provide a novel monitoring tool in preclinical IBD models, refining animal procedures and underlines the capabilities of such technologies to address inflammatory bowel diseases in humans. [ABSTRACT FROM AUTHOR]

Background: Closing mucosal defects to reach mucosal healing is an important goal of therapy in inflammatory bowel disease (IBD). Among other cells, monocyte‐derived macrophages are centrally involved in such intestinal wound healing. We had previously demonstrated that the anti‐α4β7 integrin antibody vedolizumab blocks the recruitment of non‐classical monocytes as biased progenitors of wound healing macrophages to the gut and delays wound healing. However, although important for the interpretation of disappointing results in recent phase III trials in IBD, the effects of the anti‐β7 antibody etrolizumab on wound healing are unclear so far. Methods: We analyzed the expression of etrolizumab targets on human and mouse monocyte subsets by flow cytometry and assessed their function in adhesion and homing assays. We explored wound‐associated monocyte recruitment dynamics with multiphoton microscopy and compared the effects of etrolizumab and vedolizumab surrogate (‐s) antibodies on experimental wound healing and wound‐associated macrophage abundance. Finally, we investigated wound healing macrophage signatures in the large intestinal transcriptome of patients with Crohn's disease treated with etrolizumab. Results: Human and mouse non‐classical monocytes expressed more αEβ7 integrin than classical monocytes and were a target of etrolizumab‐s, which blocked non‐classical monocyte adhesion to MAdCAM‐1 and E‐Cadherin as well as gut homing in vivo. Intestinal wound healing was delayed on treatment with etrolizumab‐s along with a reduction of peri‐lesional wound healing macrophages. Wound healing macrophage signatures in the colon of patients with Crohn's disease were substantially down‐regulated on treatment with etrolizumab, but not with placebo. Conclusions: Combined blockade of αEβ7 and α4β7 with etrolizumab seems to exceed the effect of anti‐α4β7 treatment on intestinal wound healing, which might help to inform further investigations to understand the recent observations in the etrolizumab phase III trial program. [ABSTRACT FROM AUTHOR]

Inflammatory fibrotic tissue remodeling can lead to severe morbidity. Histopathology grading requires extraction of biopsies and elaborate tissue processing. Label‐free optical technologies can provide diagnostic readout without preparation and artificial stainings and show potential for in vivo applications. Here, we present an integration of Raman spectroscopy (RS) and multiphoton microscopy for joint investigation of the bio‐chemical composition and morphological features related to cellular components and connective tissue. Both modalities show that collagen signatures were significantly increased in a murine fibrosis model. Furthermore, autofluorescence signatures assigned to immune cells show high correlation with disease severity. RS indicates increased levels of elastin and lipids. Further, we investigated the effect of joint data sets on prediction performance in machine learning models. Although binary classification did not benefit from adding more features, multi‐class classification was improved by integrated data sets. [ABSTRACT FROM AUTHOR]

Aims: Desminopathies comprise hereditary myopathies and cardiomyopathies caused by mutations in the intermediate filament protein desmin that lead to severe and often lethal degeneration of striated muscle tissue. Animal and single cell studies hinted that this degeneration process is associated with massive ultrastructural defects correlating with increased susceptibility of the muscle to acute mechanical stress. The underlying mechanism of mechanical susceptibility, and how muscle degeneration develops over time, however, has remained elusive. Methods: Here, we investigated the effect of a desmin mutation on the formation, differentiation, and contractile function of in vitro‐engineered three‐dimensional micro‐tissues grown from muscle stem cells (satellite cells) isolated from heterozygous R349P desmin knock‐in mice. Results: Micro‐tissues grown from desmin‐mutated cells exhibited spontaneous unsynchronised contractions, higher contractile forces in response to electrical stimulation, and faster force recovery compared with tissues grown from wild‐type cells. Within 1 week of culture, the majority of R349P desmin‐mutated tissues disintegrated, whereas wild‐type tissues remained intact over at least three weeks. Moreover, under tetanic stimulation lasting less than 5 s, desmin‐mutated tissues partially or completely ruptured, whereas wild‐type tissues did not display signs of damage. Conclusions: Our results demonstrate that the progressive degeneration of desmin‐mutated micro‐tissues is closely linked to extracellular matrix fibre breakage associated with increased contractile forces and unevenly distributed tensile stress. This suggests that the age‐related degeneration of skeletal and cardiac muscle in patients suffering from desminopathies may be similarly exacerbated by mechanical damage from high‐intensity muscle contractions. We conclude that micro‐tissues may provide a valuable tool for studying the organization of myocytes and the pathogenic mechanisms of myopathies. [ABSTRACT FROM AUTHOR]

Paleoclimate records from tropical South America typically show precession‐paced variability in rainfall, caused by insolation‐driven changes in the South American Monsoon System, however this mechanism may not be responsible for hydroclimate change outside of the core monsoon domain, such as in the coastal zone of tropical eastern Brazil. Our findings are based on a ∼850 kyr‐long multiproxy record from a marine sediment core collected from the eastern Brazilian margin that represents the longest continuous record of South American hydroclimate to date. Utilizing the ln (K/Al) chemical weathering proxy from the core, we determine that past hydroclimate change in the coastal zone was primarily modulated by obliquity forcing. We demonstrate that high obliquity is associated with an increase in the boreal summer interhemispheric insolation contrast which decreases the zonality of the southern trade winds and reduces moisture advection to the coastal zone. Based on the long‐term coherence between the ln (K/Al) record and benthic δ13C records from the Atlantic during Marine Isotope Stages 16–13, we infer that an increase in the strength of the overturning circulation, caused by Northern Hemisphere high‐latitude forcing, may have produced surface cooling in the western tropical South Atlantic which led to reduced moisture advection to the coastal zone. We suggest that this mechanism may have also caused the amplification in millennial‐scale variability in the coastal hydroclimate system, which began after the decoupling of the coastal hydroclimate system from obliquity forcing. Key Points: Coastal precipitation in tropical eastern Brazil is dominated by obliquity forcing over most of the past ∼850 kyrMillennial‐scale hydroclimate variability increased during the most recent ∼200 kyr, as modulation by obliquity gradually weakenedNorthern Hemisphere high‐latitude climate fluctuations are linked to hydroclimate variations in the coastal zone of tropical eastern Brazil [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) cancer models have been the standard for drug development over the past few years, but they frequently do not resemble in vivo properties adequately. 3D models are superior in many aspects and are, therefore, more similar to human pathophysiology. Over the past years, the emerging field of biofabrication has made significant advances, resulting in even more sophisticated 3D models. With this study, a hydrogel is created for biofabrication that is suitable for mimicking the tumor microenvironment in vitro and is further tested as a new vascularized melanoma model in vivo. The alginate/hyaluronic acid/gelatin bioink shows good shape‐fidelity, high cell survival rates, and enables successful cultivation of melanoma cells and adipose‐derived stem cells as well as cell differentiation in vitro. In vivo, in the arteriovenous loop model, it proves to be a unique method to study melanoma progression, tumor vascularization, and ultimately and reliably metastases in an isolated and controlled environment. These results show that this 3D model is very application‐oriented for molecular research and therapy development. [ABSTRACT FROM AUTHOR]

The Mid-Pleistocene Transition (MPT, 1,200-600 ka) marks the rapid expansion of Northern Hemisphere (NH) continental ice sheets and stronger precession pacing of glacial/interglacial cyclicity. Here, we investigate the relationship between thermocline depth in the central North Atlantic, subsurface northward heat transport and the initiation of the 100-kyr cyclicity during the MPT. To reconstruct deep-thermocline temperatures, we generated a Mg/Ca-based temperature record of deepdwelling (~800 m) planktonic foraminifera from mid-latitude North Atlantic at Site U1313. This record shows phases of pronounced heat accumulation at subsurface levels during the mid-MPT glacial driven by increased outflow of the Mediterranean Sea. Concurrent warming of the subtropical thermocline and subpolar surface waters indicates enhanced (subsurface) inter-gyre transport of warm water to the subpolar North Atlantic, which provided moisture for ice-sheet growth. Precession-modulated variability in the northward transport of subtropical waters imprinted this orbital cyclicity into NH ice-sheets after Marine Isotope Stage 24. Plain Language Summary Large continental ice-sheets are a key component of the Earth's climate system, yet the factors controlling their build-up and destabilization on geological time-scales are far from understood. One of the remarkable aspects of Pleistocene (2.58 Ma to 11.65 ka) ice-sheets is that they appear to be highly sensitive to low-latitude forcing, a teleconnection that is yet not well-understood. In this study, we investigate if changes in the subsurface transport of heat from the subtropics into the high latitude North Atlantic may have played an overlooked role in controlling ice-sheet size. To address this issue, we obtained a new record of upper ocean temperature distribution in the North Atlantic during the Mid-Pleistocene Transition (MPT, 1200-600 ka), a period when ice-sheets expanded and our climate system shifted to longer glacial cycles. Our data reveal distinct pulses of low-latitude heat that were transported northwards by the ocean, warming the surface of the high-latitude North Atlantic during cold stages of prominent ice-sheet build-up. These anomalously warm surface waters may have provided excess moisture to the adjacent ice-sheets. Thus, we suggest that subsurface transport of warm and salty waters northward imprinted low-latitude variability into high-latitude ice sheets starting during the MPT. [ABSTRACT FROM AUTHOR]

During the last deglaciation abrupt millennial‐scale perturbations of the Atlantic Meridional Overturning Circulation massively altered the interhemispheric heat distribution affecting, for example, continental ice volume and hydroclimate. If and how the related cross‐equatorial heat transport was controlled by the interplay between the southward‐flowing Brazil Current (BC) and northward‐flowing North Brazil Current (NBC) remains controversial. To assess the role of tropical heat transport during the last deglaciation, we obtained a high‐resolution foraminiferal Mg/Ca‐based sea surface temperature (SST) record from the BC domain at 21.5°S. The data reveal a yet undocumented warming of at least 4.6°C of the BC during Heinrich Stadial 1 at ∼16 ka indicating massive oceanic heat accumulation in the tropical South Atlantic. Simultaneously, a strongly diminished NBC prevented the release of this excess heat into the northern tropics. The observed magnitude of heat accumulation substantially exceeds numerical model simulations, stressing the need to further scrutinize atmospheric and oceanic heat transport during extreme climatic events. Plain Language Summary: The Atlantic overturning circulation underwent abrupt millennial‐scale perturbations. Such phases of sluggish oceanic circulation resulted in a substantial reduction of northward heat transport. As a consequence, substantial cooling occurred in the Northern Hemisphere and warming occurred in the Southern Hemisphere with severe effects on tropical precipitation. The distribution of heat within the western tropical Atlantic is accomplished by the southward‐flowing BC and the northward‐flowing NBC. By reconstructing SSTs for the interval between 20,000 and 10,000 yr before present, we assess the role of both currents in the interhemispheric heat transport during weak Atlantic overturning. We found that a sluggish overturning circulation resulted in anomalous southward heat transport by the BC in concert with a weak NBC, which lead to a yet undocumented warming of at least 4.6°C in the western tropical South Atlantic. This warming significantly exceeds reconstructions based on numerical simulations. This points to the need to further improve our understanding of changes in the cross‐equatorial oceanic and atmospheric heat transport in response to rapid changes in ocean circulation, in particular as a significant weakening of the Atlantic overturning circulation is predicted in the wake of anthropogenic climate change. Key Points: Brazil Current heat transport coupled to changes in strength of the Atlantic Meridional Overturning Circulation during the last deglacialAntiphased heat transport by the Brazil and North Brazil Currents during Heinrich Event 1Warming of western tropical South Atlantic sea surface based on foraminiferal Mg/Ca exceeds numerical model results for Heinrich Event 1 [ABSTRACT FROM AUTHOR]

Upwelling within the Eastern Equatorial Pacific (EEP) Ocean is a key factor for the Earth's climate because it supports >10% of the present‐day biological production. The dynamics of upwelling in the EEP across the Plio‐Pleistocene transition—an interval particularly relevant for understanding near‐future warming due to Anthropocene‐like atmospheric carbon‐dioxide levels—have been intensively studied for the region east of the East Pacific Rise. In contrast, changes of the equatorial upwelling regime in the open Pacific Ocean west of this oceanographic barrier have received markedly less attention. We therefore provide new proxy records from Ocean Drilling Program Site 849 located within the EEP open‐ocean upwelling regime. Our target interval (∼3.35–2.0 Ma) covers the Plio‐Pleistocene transition characterized by the intensification of Northern Hemisphere Glaciation (iNHG). We use benthic δ18O values to generate a new, high‐resolution age model for Site 849, and sand‐accumulation rates together with benthic δ13C values to evaluate net export production. Although showing temporary substantial glacial‐interglacial variations, our records indicate stability in net export production on secular timescales across the iNHG. We suggest the following processes to have controlled the long‐term evolution of primary productivity at Site 849. First, nutrient export from the high latitudes to the EEP; second, a successive shoaling of the Pacific nutricline during the studied interval; and third, a simultaneous reduction in dust‐borne iron input. Key Points: Glacial‐interglacial change in net export production at East Pacific Site 849 from ∼3.35 to 2.0 MaNo secular change in net export production in the East Pacific across the Plio‐Pleistocene transitionNet export production on secular timescales regulated by nutrient content of upwelled waters, nutricline dynamics, and iron fertilization [ABSTRACT FROM AUTHOR]

Background: Prolonged critically ill patients frequently develop debilitating muscle weakness that can affect both peripheral nerves and skeletal muscle. In‐depth knowledge on the temporal contribution of neural and muscular components to muscle weakness is currently incomplete. Methods: We used a fluid‐resuscitated, antibiotic‐treated, parenterally fed murine model of prolonged (5 days) sepsis‐induced muscle weakness (caecal ligation and puncture; n = 148). Electromyography (EMG) measurements were performed in two nerve–muscle complexes, combined with histological analysis of neuromuscular junction denervation, axonal degeneration, and demyelination. In situ muscle force measurements distinguished neural from muscular contribution to reduced muscle force generation. In myofibres, imaging and biomechanics were combined to evaluate myofibrillar contractile calcium sensitivity, sarcomere organization, and fibre structural properties. Myosin and actin protein content and titin gene expression were measured on the whole muscle. Results: Five days of sepsis resulted in increased EMG latency (P = 0.006) and decreased EMG amplitude (P < 0.0001) in the dorsal caudal tail nerve–tail complex, whereas only EMG amplitude was affected in the sciatic nerve–gastrocnemius muscle complex (P < 0.0001). Myelin sheath abnormalities (P = 0.2), axonal degeneration (number of axons; P = 0.4), and neuromuscular junction denervation (P = 0.09) were largely absent in response to sepsis, but signs of axonal swelling [higher axon area (P < 0.0001) and g‐ratio (P = 0.03)] were observed. A reduction in maximal muscle force was present after indirect nerve stimulation (P = 0.007) and after direct muscle stimulation (P = 0.03). The degree of force reduction was similar with both stimulations (P = 0.2), identifying skeletal muscle, but not peripheral nerves, as the main contributor to muscle weakness. Myofibrillar calcium sensitivity of the contractile apparatus was unaffected by sepsis (P ≥ 0.6), whereas septic myofibres displayed disorganized sarcomeres (P < 0.0001) and altered myofibre axial elasticity (P < 0.0001). Septic myofibres suffered from increased rupturing in a passive stretching protocol (25% more than control myofibres; P = 0.04), which was associated with impaired myofibre active force generation (P = 0.04), linking altered myofibre integrity to function. Sepsis also caused a reduction in muscle titin gene expression (P = 0.04) and myosin and actin protein content (P = 0.05), but not the myosin‐to‐actin ratio (P = 0.7). Conclusions: Prolonged sepsis‐induced muscle weakness may predominantly be related to a disruption in myofibrillar cytoarchitectural structure, rather than to neural abnormalities. [ABSTRACT FROM AUTHOR]

Key points: Physical activity is known to protect against cancer.The resistance exercise method whole‐body electromyostimulation (WB‐EMS) has a significant anti‐cancer effect.WB‐EMS‐conditioned serum from advanced prostate cancer patients decreased human prostate carcinoma cell growth and viability in vitro.Multiplex analysis revealed that genes associated with human prostate cancer cell proliferation and apoptosis are sensitive for exercise.Feasible exercise should be part of multimodal anti‐cancer therapies, also for physically weakened patients. Regular physical activity is known to protect against cancer development. In cancer survivors, exercise reduces the risk of cancer recurrence and mortality. However, the link between exercise and decreased cancer risk and improved survival is still not well understood. Serum from exercising healthy individuals inhibits proliferation and activates apoptosis in various cancer cells, suggesting that mechanisms regulating cancer cell growth are affected by exercise. For the first time, we analysed serum from advanced‐stage cancer patients with prostate (exercise group n = 8; control group n = 10) or colorectal (exercise n = 6; control n = 6) cancer, after a 12‐week whole‐body electromyostimulation training (20 min/session, 2×/week; frequency 85 Hz; pulse width 350 µs; 6 s stimulation, 4 s rest), a tolerable, yet effective, resistance exercise for physically weakened patients. We report that serum from these advanced cancer patients inhibits proliferation and enhances apoptosis of human prostate and colon cancer cells in vitro using cell growth and death assays (5‐bromo‐2′‐deoxyuridine incorporation, cell counting, DNA fragmentation). Exercise‐mimicking electric pulse stimulation of human primary myotubes showed that electric pulse stimulation‐conditioned myotube medium also impairs human cancer cell viability. Gene expression analysis using a multiplex array of cancer‐associated genes and subsequent quantitative RT‐PCR revealed the presence of exercise‐sensitive genes in human prostate cancer cells that potentially participate in the exercise‐mediated regulation of malignant cell growth and apoptosis. Our data document the strong efficiency of the anti‐oncogenic effects of physical activity and will further support the application of regular therapeutic exercise during cancer disease. Key points: Physical activity is known to protect against cancer.The resistance exercise method whole‐body electromyostimulation (WB‐EMS) has a significant anti‐cancer effect.WB‐EMS‐conditioned serum from advanced prostate cancer patients decreased human prostate carcinoma cell growth and viability in vitro.Multiplex analysis revealed that genes associated with human prostate cancer cell proliferation and apoptosis are sensitive for exercise.Feasible exercise should be part of multimodal anti‐cancer therapies, also for physically weakened patients. [ABSTRACT FROM AUTHOR]

Precipitation extremes with devastating socioeconomic consequences within the South American Monsoon System (SAMS) are expected to become more frequent in the near future. The complexity in SAMS behavior, however, poses severe challenges for reliable future projections. Thus, robust paleomonsoon records are needed to constrain the high spatiotemporal variability in the response of SAMS rainfall to different climatic drivers. This study uses Ti/Ca ratios from X‐ray fluorescence scanning of a sediment core retrieved off eastern Brazilian to trace precipitation changes over the past 322 Kyr. The results indicate that despite the spatiotemporal complexity of the SAMS, insolation forcing is the primary pacemaker of variations in the monsoonal system. Additional modulation by atmospheric pCO2 suggests that SAMS intensity over eastern Brazil will be suppressed by rising CO2 emissions in the future. Lastly, our record reveals an unprecedented strong and persistent wet period during Marine Isotope Stage 6 driven by anomalously strong trade winds. Key Points: Insolation is the main driver of orbital‐scale South American Monsoon System rainfall variability in eastern Brazil over the past 322 kyrMonsoonal rainfall intensity is indirectly modulated by greenhouse gas forcing through changes to the latitudinal temperature gradientsDuring MIS 6, precipitation in eastern Brazil remained anomalously strong and deviated from the regular orbitally paced insolation forcing [ABSTRACT FROM AUTHOR]

The intensification of Northern Hemisphere glaciation (iNHG) and uplift of the Tibetan Plateau have been argued to be among the main drivers of climate change in midlatitude Central Asia during the Pliocene/Pleistocene. While most proxy records that support this hypothesis are from regions outside the Tibetan Plateau (such as from the Chinese Loess Plateau), detailed paleoclimatic information for the plateau itself during that time has yet remained elusive. Here we present a temporally highly resolved (~500 years) sedimentological record from the Qaidam Basin situated on the northeastern Tibetan Plateau that shows pronounced glacial‐interglacial climate variability during the interval from 2.7 to 2.1 Ma. Glacial (interglacial) intervals are generally characterized by coarser (finer) grain size, minima (maxima) in organic matter content, and maxima (minima) in carbonate content. Comparison of our results with Earth's orbital parameters and proxy records from the Chinese Loess Plateau suggests that the observed climate fluctuations were mainly driven by changes in the Siberian High/East Asian winter monsoon system as a response to the iNHG. They are further proposed to be enhanced by the topography of the Tibetan Plateau and its impact on the position and intensity of the westerlies. Key Points: Pronounced glacial‐interglacial climate fluctuations on the NE Tibetan Plateau during the latest Pliocene and early PleistoceneChanges in East Asian Winter Monsoon and the position of the westerlies influenced sediment transport on the NE Tibetan PlateauIntensification of Northern Hemisphere glaciation amplified climate fluctuations on the NE Tibetan Plateau [ABSTRACT FROM AUTHOR]

The formation of the supercontinent Pangaea during the Permo–Triassic gave rise to an extreme monsoonal climate (often termed 'mega‐monsoon') that has been documented by numerous palaeo‐records. However, considerable debate exists about the role of orbital forcing in causing humid intervals in an otherwise arid climate. To shed new light on the forcing of monsoonal variability in subtropical Pangaea, this study focuses on sediment facies and colour variability of playa and alluvial fan deposits in an outcrop from the late Carnian (ca 225 Ma) in the southern Germanic Basin, south‐western Germany. The sediments were deposited against a background of increasingly arid conditions following the humid Carnian Pluvial Event (ca 234 to 232 Ma). The ca 2·4 Myr long sedimentary succession studied shows a tripartite long‐term evolution, starting with a distal mud‐flat facies deposited under arid conditions. This phase was followed by a highly variable playa‐lake environment that documents more humid conditions and finally a regression of the playa‐lake due to a return of arid conditions. The red–green (a*) and lightness (L*) records show that this long‐term variability was overprinted by alternating wet/dry cycles driven by orbital precession and ca 405 kyr eccentricity, without significant influence of obliquity. The absence of obliquity in this record indicates that high‐latitude forcing played only a minor role in the southern Germanic Basin during the late Carnian. This is different from the subsequent Norian when high‐latitude signals became more pronounced, potentially related to the northward drift of the Germanic Basin. The recurring pattern of pluvial events during the late Triassic demonstrates that orbital forcing, in particular eccentricity, stimulated the occurrence and intensity of wet phases. It also highlights the possibility that the Carnian Pluvial Event, although most likely triggered by enhanced volcanic activity, may also have been modified by an orbital stimulus. [ABSTRACT FROM AUTHOR]

There is a converging body of evidence supporting a measurable slowdown of the Atlantic Meridional Overturning Circulation (AMOC) as climate warms and Northern Hemisphere ice sheets inexorably shrink. Within this context, we assess the variability of the AMOC during the Holocene based on a marine sediment core retrieved from the deep northwest Atlantic, which sensitively recorded large‐scale deglacial transitions in deep water circulation. While there is a diffuse notion of Holocene variability in Labrador and Nordic Seas overturning, we report a largely invariable deep water circulation for the last ~11,000 years, even during the meltwater pulse associated with the 8.2‐ka event. Sensitivity tests along with high‐resolution 231Pa/230Th data constrain the duration and the magnitude of possible Holocene AMOC variations. The generally constant baseline during the Holocene suggests attenuated natural variability of the large‐scale AMOC on submillennial timescales and calls for compensating effects involving the upstream components of North Atlantic Deep Water. Key Points: High‐resolution 231Pa/230Th record from the Bermuda Rise for the past 11,000 years presentedLow variability of Holocene AMOC derived from 231Pa/230Th, εNd and δ13CDuration and magnitude of the 8.2‐ka event constrained by sensitivity tests [ABSTRACT FROM AUTHOR]

A substantial challenge worldwide is emergent drug resistance in malaria parasites against approved drugs, such as chloroquine (CQ). To address these unsolved CQ resistance issues, only rare examples of artemisinin (ART)‐based hybrids have been reported. Moreover, protein targets of such hybrids have not been identified yet, and the reason for the superior efficacy of these hybrids is still not known. Herein, we report the synthesis of novel ART–isoquinoline and ART–quinoline hybrids showing highly improved potencies against CQ‐resistant and multidrug‐resistant P. falciparum strains (EC50 (Dd2) down to 1.0 nm; EC50 (K1) down to 0.78 nm) compared to CQ (EC50 (Dd2)=165.3 nm; EC50 (K1)=302.8 nm) and strongly suppressing parasitemia in experimental malaria. These new compounds are easily accessible by step‐economic C−H activation and copper(I)‐catalyzed azide–alkyne cycloaddition (CuAAC) click reactions. Through chemical proteomics, putatively hybrid‐binding protein targets of the ART‐quinolines were successfully identified in addition to known targets of quinoline and artemisinin alone, suggesting that the hybrids act through multiple modes of action to overcome resistance. [ABSTRACT FROM AUTHOR]

The North Atlantic Current (NAC) transports warm salty water to high northern latitudes, with important repercussions for ocean circulation and global climate. A southward displacement of the NAC and Subarctic Front, which separate subpolar and subtropical water masses, is widely suggested for the Last Glacial Maximum (LGM) and may have acted as a positive feedback in glacial expansion at this time. However, the role of the NAC during the intensification of Northern Hemisphere glaciation (iNHG) at ~3.5 to 2.5 Ma is less clear. Here we present new records from Integrated Ocean Drilling Program Site U1313 (41°N) spanning ~2.8–2.4 Ma to trace the influence of Subarctic Front waters above this mid‐latitude site. We reconstruct surface and permanent pycnocline temperatures and seawater δ18O using paired Mg/Ca‐δ18O measurements on the planktic foraminifers Globigerinoides ruber and Globorotalia crassaformis and determine abundances of the subpolar foraminifer Neogloboquadrina atlantica. We find that the first significant glacial incursions of Subarctic Front surface waters above Site U1313 did not occur until ~2.6 Ma. At no time during our study interval was (sub)surface reorganization in the midlatitude North Atlantic analogous to the LGM. Our findings suggest that LGM‐like processes sensu stricto cannot be invoked to explain interglacial‐glacial cycle amplification during iNHG. They also imply that increased glacial productivity at Site U1313 during iNHG was not only driven by southward deflections of the Subarctic Front. We suggest that nutrient injection from cold‐core eddies and enhanced glacial dust delivery may have played additional roles in increasing export productivity in the midlatitude North Atlantic from 2.7 Ma. Key Points: North Atlantic (sub)surface temperature and seawater δ18O reconstructions during the intensification of Northern Hemisphere glaciationSouthward shifts of Subarctic Front during the intensification of Northern Hemisphere glaciation not analogous to the Last Glacial MaximumDust and/or eddies are important drivers of glacial export productivity at 41°N from 2.7 Ma [ABSTRACT FROM AUTHOR]

Abstract: The dynamics of Northern Hemisphere ice sheets during Late Quaternary glacials have yet been dominantly examined from a Laurentide Ice Sheet perspective, which helped shaping the idea of moisture‐starved glacials and small‐scale ice volume variability. However, the waxing and waning of the European Ice Sheet (EIS) casts doubt on this perception. Understanding EIS dynamics under glacial boundary conditions is crucial because its meltwater pulses influence global climate by weakening deepwater formation in the North Atlantic Ocean. Here we show that the advection of subtropical water toward the continental margin of western Europe lead to enhanced moisture availability on the continent and fueled the growth of EIS lobes during glacials. This warm‐water pooling was caused by monsoonally paced enhanced Mediterranean Outflow Water (MOW) entrainment that dragged subtropical surface waters toward the European margin. This mechanism presents a yet unrecognized marine‐terrestrial pathway that allows low‐latitude forcing to shape high‐latitude glaciations. [ABSTRACT FROM AUTHOR]

Abstract: Generation of dimers, trimers and dendrimers of bioactive compounds is an approach that has recently been developed for the discovery of new potent drug candidates. Herein, we present the synthesis of new artemisinin‐derived dimers and dendrimers and investigate their action against malaria parasite Plasmodium falciparum 3D7 strain and human cytomegalovirus (HCMV). Dimer 7 was the most active compound (EC50 1.4 n m) in terms of antimalarial efficacy and was even more effective than the standard drugs dihydroartemisinin (EC50 2.4 n m), artesunic acid (EC50 8.9 n m) and chloroquine (EC50 9.8 n m). Trimer 4 stood out as the most active agent against HCMV in vitro replication and exerted an EC50 value of 0.026 μ m, representing an even higher activity than the two reference drugs ganciclovir (EC50 2.60 μ m) and artesunic acid (EC50 5.41 μ m). In addition, artemisinin‐derived dimer 13 and trimer 15 were for the first time both immobilized on TOYOPEARL AF‐Amino‐650M beads and used for mass spectrometry‐based target identification experiments using total lysates of HCMV‐infected primary human fibroblasts. Two major groups of novel target candidates, namely cytoskeletal and mitochondrial proteins were obtained. Two putatively compound‐binding viral proteins, namely major capsid protein (MCP) and envelope glycoprotein pUL132, which are both essential for HCMV replication, were identified. [ABSTRACT FROM AUTHOR]

The straightforward and efficient synthesis of complex aza- and carbobicyclic compounds, which are of importance for medicinal chemistry, is a challenge for modern chemical methodology. An unprecedented metal-free six-step domino reaction of aldehydes with malononitrile was presented in our previous study to provide, in a single operation, these bicyclic nitrogen-containing molecules. Presented here is a deeper investigation of this atom-economical domino process by extending the scope of aldehydes, performing post-modifications of domino products, applying bifunctional organocatalysts and comprehensive NMR studies of selected domino products. The thermodynamic aspects of the overall reaction are also demonstrated using DFT methods in conjunction with a semi-empirical treatment of van der Waals interactions. Furthermore, biological studies of seven highly functionalized and artemisinin-containing domino products against human cytomegalovirus (HCMV) and Plasmodium falciparum 3D7 are presented. Remarkably, in vitro tests against HCMV revealed five domino products to be highly active compounds (EC50 0.071-1.8 μ m), outperforming the clinical reference drug ganciclovir (EC50 2.6 μ m). Against P. falciparum 3D7, three of the investigated artemisinin-derived domino products (EC50 0.72-1.8 n m) were more potent than the clinical drug chloroquine (EC50 9.1 n m). [ABSTRACT FROM AUTHOR]

Passive mechanics plays an important role during the electromechanically coupled cardiac cycle and its behaviour strongly changes after myocardial infarction. In the present work, the cardiac tissue is modelled as a mixture of an active orthotropic intact myocardium and a passive transversely isotropic fibrotic scar structure. We apply the constitutive model on the fully electromechanically coupled simulation of a cardiac cycle using a generic geometry of a rat left ventricle. Finally, the ejection fractions for various parameter sets based on the fitting to experimental data in different animal species as well as for a varying amount of fibrosis are compared. We show that both, the choice of species‐specific passive material parameters and the amount of fibrosis, have a significant influence on the cardiac performance measured by the ejection fraction of the left ventricle. [ABSTRACT FROM AUTHOR]

Key points Marijuana was found to cause muscle weakness, although the exact regulatory role of its receptors (CB1 cannabinoid receptor; CB1R) in the excitation-contraction coupling (ECC) of mammalian skeletal muscle remains unknown., We found that CB1R activation or its knockout did not affect muscle force directly, whereas its activation decreased the Ca2+-sensitivity of the contractile apparatus and made the muscle fibres more prone to fatigue., We demonstrate that CB1Rs are not connected to the inositol 1,4,5-trisphosphate pathway either in myotubes or in adult muscle fibres., By contrast, CB1Rs constitutively inhibit sarcoplasmic Ca2+ release and sarcoplasmic reticulum Ca2+ ATPase during ECC in a Gi/o protein-mediated way in adult skeletal muscle fibres but not in myotubes., These results help with our understanding of the physiological effects and pathological consequences of CB1R activation in skeletal muscle and may be useful in the development of new cannabinoid drugs., Abstract Marijuana was found to cause muscle weakness, although it is unknown whether it affects the muscles directly or modulates only the motor control of the central nervous system. Although the presence of CB1 cannabinoid receptors (CB1R), which are responsible for the psychoactive effects of the drug in the brain, have recently been demonstrated in skeletal muscle, it is unclear how CB1R-mediated signalling affects the contraction and Ca²⁺ homeostasis of mammalian skeletal muscle. In the present study, we demonstrate that in vitro CB1R activation increased muscle fatigability and decreased the Ca2+-sensitivity of the contractile apparatus, whereas it did not alter the amplitude of single twitch contractions. In myotubes, CB1R agonists neither evoked, nor influenced inositol 1,4,5-trisphosphate (IP3)-mediated Ca2+ transients, nor did they alter excitation-contraction coupling. By contrast, in isolated muscle fibres of wild-type mice, although CB1R agonists did not evoke IP3-mediated Ca2+ transients too, they significantly reduced the amplitude of the depolarization-evoked transients in a pertussis-toxin sensitive manner, indicating a Gi/o protein-dependent mechanism. Concurrently, on skeletal muscle fibres isolated from CB1R-knockout animals, depolarization-evoked Ca2+ transients, as well qas Ca2+ release flux via ryanodine receptors (RyRs), and the total amount of released Ca2+ was significantly greater than that from wild-type mice. Our results show that CB1R-mediated signalling exerts both a constitutive and an agonist-mediated inhibition on the Ca2+ transients via RyR, regulates the activity of the sarcoplasmic reticulum Ca2+ ATPase and enhances muscle fatigability, which might decrease exercise performance, thus playing a role in myopathies, and therefore should be considered during the development of new cannabinoid drugs. [ABSTRACT FROM AUTHOR]

Human pluripotent embryonal carcinoma ( NT2) cells are increasingly considered as a suitable model for in vitro developmental toxicity and neurotoxicity ( DT/ DNT) studies as they undergo neuronal differentiation upon stimulation with retinoic acid ( RA) and allow toxicity testing at different stages of maturation. However, differentiation of NT2 cells is not straightforward. There are different protocols available in the literature reporting varying results with regard to differentiation efficiency, expression of neuronal markers and morphological characteristics of differentiated cells. Yet, the efficiency of available protocols has not been systematically compared. To address this question, we quantified the number and size of cell cluster formed during differentiation using published and modified protocols and analyzed the abundance of neuronal and non-neuronal expression markers using immunocytochemistry. In the course of the experiments we observed that differentiation results strongly depend on the cell density at differentiation-initiation as well as on the type of used cell culture plastic ware. Based on those observations and the results from our comparative analysis, we created our own optimized and robust protocol that reproducibly reveals differentiated cells with high yield. We conclude that our method may be superior to differentiation of NT2 cells for systematic in vitro-based primary screening for developmental toxicants and neurotoxicants at different stages of maturation over previous protocols used. Our approach will also contribute to reduce animal testing in the context of the 3Rs. [ABSTRACT FROM AUTHOR]

Label‐free optical technologies provide tissue features without tissue preparation and artificial stainings that are typically used in conventional pathology. Here, Raman spectroscopy is integrated to multiphoton microscopy for joint investigation of the bio‐chemistry and morphology in murine lung fibrosis, revealing molecular fingerprints, cellular components and connective tissue. Machine learning models can then use these label‐free features for automated prediction of conventional pathological scores. Further details can be found in the article by Lucas Kreiss, Ingo Ganzleben, Alexander Mühlberg, Paul Ritter, Dominik Schneidereit, Christoph Becker, Markus F. Neurath, Oliver Friedrich, Sebastian Schürmann, and Maximilian Waldner (e202200073) [ABSTRACT FROM AUTHOR]

Cachexia presents with ongoing muscle wasting, altering quality of life in cancer patients. Cachexia is a limiting prognostic factor for patient survival and health care costs. Although animal models and human trials have shown mechanisms of motorprotein proteolysis, not much is known about intrinsic changes of muscle functionality in cancer patients suffering from muscle cachexia, and deeper insights into cachexia pathology in humans are needed. To address this question, rectus abdominis muscle samples were collected from several surgical control, non-cachectic and cachectic cancer patients and processed for skinned fibre biomechanics, molecular in vitro motility assays, myosin isoform protein compositions and quantitative ubiquitin polymer protein analysis. In pre-cachectic and cachectic cancer patient samples, maximum force was significantly compromised compared with controls, but showed an unexpected increase in myofibrillar Ca2+ sensitivity consistent with a shift from slow to fast myosin isoform expression seen in SDS- PAGE analysis and in vitro motility assays. Force deficit was specific for 'cancer', but not linked to presence of cachexia. Interestingly, quantitative ubiquitin immunoassays revealed no major changes in static ubiquitin polymer protein profiles, whether cachexia was present or not and were shown to mirror profiles in control patients. Our study on muscle function in cachectic patients shows that abdominal wall skeletal muscle in cancer cachexia shows signs of weakness that can be partially attributed to intrinsic changes to contractile motorprotein function. On protein levels, static ubiquitin polymeric distributions were unaltered, pointing towards evenly up-regulated ubiquitin protein turnover with respect to ubiquitin conjugation, proteasome degradation and de-ubiquitination. [ABSTRACT FROM AUTHOR]

ABSTRACT The plethora of available scientific cameras of different types challenges the biologically oriented experimenter when picking the appropriate camera for his experiment. In this study, we chose to investigate camera performances in a typical nonsingle molecule situation in life sciences, that is, quantitative measurements of fluorescence intensity changes from video data with typically skewed intensity distributions. Here, intensity profile dynamics of pH-sensors upon triggered changes of pH-environments in living cells served as a model system. The following camera types were tested: sCMOS, CCD (scientific and nonscientific) and EM-CCD (back- and front-illuminated). We found that although the EM-CCD cameras achieved the best absolute spatial SNR (signal-to-noise ratio) values, the sCMOS was at least of equal performance when the spatial SNR was related to the effective dynamic range, and it was superior in terms of temporal SNR. In the measurements of triggered intensity changes, the sCMOS camera had the advantage that it used the smallest fraction of its dynamic range when depicting intensity changes, and thus featured the best SNR at full usage of its dynamic range. Microsc. Res. Tech. 76:835-843, 2013. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Duchenne muscular dystrophy ( DMD) is a common inherited muscle disease showing chronic inflammation and progressive muscle weakness. Absent dystrophin renders sarcolemma more Ca2+-permeable, disturbs signalling and triggers inflammation. Sustained degeneration/regeneration cycles render muscle cytoarchitecture susceptible to remodelling. Quantitative morphometry was introduced in living cells using second-harmonic generation ( SHG) microscopy of myosin. As the time course of cellular remodelling is not known, we used SHG microscopy in mdx muscle fibres over a wide age range for three-dimensional ( 3D) rendering and detection of verniers and cosine angle sums ( CASs). Wild-type (wt) and transgenic mini-dystrophin mice ( MinD) were also studied. Vernier densities ( VDs) declined in wt and MinD fibres until adulthood, while in mdx fibres, VDs remained significantly elevated during the life span. CAS values were close to unity in adult wt and MinD fibres, in agreement with tight regular myofibril orientation, while always smaller in mdx fibres. Using SHG 3D morphometry, we identified two types of altered ultrastructure: branched fibres and a novel, previously undetected 'chaotic' fibre type, both of which can be classified by distinct CAS and VD combinations. We present a novel model of tissue remodelling in dystrophic progression with age that involves the transition from normal to chaotic to branched fibres. Our model predicts a ∼50% contribution of altered cytoarchitecture to progressive force loss with age. We also provide an improved automated image algorithm that is suitable for future ageing studies in human myopathies. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Progressive cardiomyopathy is a major cause of death in Duchenne muscular dystrophy ( DMD) patients. Coupling between Ca2+ handling and contractile properties in dystrophic hearts is poorly understood. It is also not clear whether developing cardiac failure is dominated by alterations in Ca2+ pathways or more related to the contractile apparatus. We simultaneously recorded force and Ca2+ transients in field-stimulated papillary muscles from young (10-14 weeks) wild-type (wt) and dystrophic mdx mice. Force amplitudes were fivefold reduced in mdx muscles despite only 30 % reduction in fura-2 ratio amplitudes. This indicated mechanisms other than systolic Ca2+ to additionally account for force decrements in mdx muscles. p Ca-force relations revealed decreased mdx myofibrillar Ca2+ sensitivity. ' In vitro' motility assays, studied in mdx hearts here for the first time, showed significantly slower sliding velocities. mdx MLC/ MHC isoforms were not grossly altered. Dystrophic hearts showed echocardiography signs of early ventricular wall hypertrophy with a significantly enlarged end-diastolic diameter ' in vivo'. However, fractional shortening was still comparable to wt mice. Changes in the contractile apparatus satisfactorily explained force drop in mdx hearts. We give first evidence of early hypertrophy in mdx mice and possible mechanisms for already functional impairment of cardiac muscle in DMD. [ABSTRACT FROM AUTHOR]

Periods of low frequency stimulation are known to increase the net Ca2+ uptake in skeletal muscle but the mechanism responsible for this Ca2+ entry is not known. In this study a novel high-resolution fluorescence microscopy approach allowed the detection of an action potential-induced Ca2+ flux across the tubular (t-) system of rat extensor digitorum longus muscle fibres that appears to be responsible for the net uptake of Ca2+ in working muscle. Action potentials were triggered in the t-system of mechanically skinned fibres from rat by brief field stimulation and t-system [Ca2+] ([Ca2+]t-sys) and cytoplasmic [Ca2+] ([Ca2+]cyto) were simultaneously resolved on a confocal microscope. When initial [Ca2+]t-sys was ≥ 0.2 mm a Ca2+ flux from t-system to the cytoplasm was observed following a single action potential. The action potential-induced Ca2+ flux and associated t-system Ca2+ permeability decayed exponentially and displayed inactivation characteristics such that further Ca2+ entry across the t-system could not be observed after 2–3 action potentials at 10 Hz stimulation rate. When [Ca2+]t-sys was closer to 0.1 mm, a transient rise in [Ca2+]t-sys was observed almost concurrently with the increase in [Ca2+]cyto following the action potential. The change in direction of Ca2+ flux was consistent with changes in the direction of the driving force for Ca2+. This is the first demonstration of a rapid t-system Ca2+ flux associated with a single action potential in mammalian skeletal muscle. The properties of this channel are inconsistent with a flux through the L-type Ca2+ channel suggesting that an as yet unidentified t-system protein is conducting this current. This action potential-activated Ca2+ flux provides an explanation for the previously described Ca2+ entry and accumulation observed with prolonged, intermittent muscle activity. [ABSTRACT FROM AUTHOR]

The P-glycoprotein homolog of the human malaria parasite Plasmodium falciparum (Pgh-1) has been implicated in decreased susceptibility to several antimalarial drugs, including quinine, mefloquine and artemisinin. Pgh-1 mainly resides within the parasite's food vacuolar membrane. Here, we describe a surrogate assay for Pgh-1 function based on the subcellular distribution of Fluo-4 acetoxymethylester and its free fluorochrome. We identified two distinct Fluo-4 staining phenotypes: preferential staining of the food vacuole versus a more diffuse staining of the entire parasite. Genetic, positional cloning and pharmacological data causatively link the food vacuolar Fluo-4 phenotype to those Pgh-1 variants that are associated with altered drug responses. On the basis of our data, we propose that Pgh-1 imports solutes, including certain antimalarial drugs, into the parasite's food vacuole. The implications of our findings for drug resistance mechanisms and testing are discussed. [ABSTRACT FROM AUTHOR]

Depolarisation of the plasma membrane has been shown to be actively regulated during lymphocyte-apoptosis. Here, we present data about anti-Fas and As2O3 induced depolarisation of myeloid U-937 cells. Anti-Fas but not As2O3-induced depolarisation was significantly dependent on caspase-activation. Na+-fluxes contributed to the depolarisation in early stages of As2O3-induced apoptosis, whereas the membrane potential in late stages depended on Cl--fluxes. Cl--channels also played an important role in the induction of cell shrinkage in As2O3-induced apoptosis. However, none of these ions contributed significantly to anti-Fas induced depolarisation. This indicates the existence of different mechanisms for apoptotic plasma membrane depolarisation within one cell type. [Copyright &y& Elsevier]

Innenrücktitelbild: Artemisinin-(Iso)quinoline Hybrids by C-H Activation and Click Chemistry: Combating Multidrug-Resistant Malaria (Angew. Keywords: Antimalaria-Wirkstoffe; Artemisinin; Proteomik; Wirkstoff-Konjugate; Wirkstoff-Resistenz Antimalaria-Wirkstoffe, Artemisinin, Proteomik, Wirkstoff-Konjugate, Wirkstoff-Resistenz. [Extracted from the article]

Multiphoton microscopy of cellular autofluorescence and second harmonic generation from collagen facilitates imaging of living cells and tissues without the need for additional fluorescent labels. Here, a compact multiphoton endomicroscope for label‐free in vivo imaging in small animals via side‐viewing needle objectives is presented. Minimal invasive imaging at cellular resolution is performed in colonoscopy of mice without surgical measures and without fluorescent dyes as a contrast agent. The colon mucosa is imaged repeatedly in the same animal in a mouse model of acute intestinal inflammation to study the process of inflammation at the tissue level within a time period of ten days, demonstrating the capabilities of label‐free endomicroscopy for longitudinal studies for the first time. [ABSTRACT FROM AUTHOR]

A high‐pressure optical chamber, PiezoGRIN, that facilitates label‐free 3D high‐resolution live‐cell multiphoton microscopy in thick tissue samples is presented. A set of two Gradient Index (GRIN) rod lenses is integrated into the chamber as an optical guide and allows for the adjustment of the focal plane through the sample providing a field of view volume of 450 × 450 × 500 µm (x, y, z). An optical lateral resolution of 0.8 µm is achieved by using two‐photon excitation with 150 fs pulses of a 810 nm titanium–sapphire laser at hydrostatic pressures up to 200 MPa. With the PiezoGRIN setup, it is possible to follow pressure‐induced changes in subcellular structure of unstained vital mouse skeletal muscle tissue up to 200 µm below the tissue surface. A high‐pressure chamber for high‐resolution microscopic observation of biological samples is developed (PiezoGRIN). Applying gradient index rod lenses as pressure windows enables the PiezoGRIN to perform 3D‐multiphoton microscopy (e.g., label‐free second harmonic generation imaging) on living tissue under high hydrostatic pressure up to 200 MPa while keeping chamber construction costs low and applicability highly versatile. [ABSTRACT FROM AUTHOR]