Benchtop mesoSPIM: a next-generation open-source light-sheet microscope for cleared samples.

In 2015, we launched the mesoSPIM initiative, an open-source project for making light-sheet microscopy of large cleared tissues more accessible. Meanwhile, the demand for imaging larger samples at higher speed and resolution has increased, requiring major improvements in the capabilities of such microscopes. Here, we introduce the next-generation mesoSPIM ("Benchtop") with a significantly increased field of view, improved resolution, higher throughput, more affordable cost, and simpler assembly compared to the original version. We develop an optical method for testing detection objectives that enables us to select objectives optimal for light-sheet imaging with large-sensor cameras. The improved mesoSPIM achieves high spatial resolution (1.5 µm laterally, 3.3 µm axially) across the entire field of view, magnification up to 20×, and supports sample sizes ranging from sub-mm up to several centimeters while being compatible with multiple clearing techniques. The microscope serves a broad range of applications in neuroscience, developmental biology, pathology, and even physics.

Removal of extracellular human amyloid beta aggregates by extracellular proteases in C. elegans.

The amyloid beta (Aß) plaques found in Alzheimer's disease (AD) patients' brains contain collagens and are embedded extracellularly. Several collagens have been proposed to influence Aß aggregate formation, yet their role in clearance is unknown. To investigate the potential role of collagens in forming and clearance of extracellular aggregates in vivo, we created a transgenic Caenorhabditis elegans strain that expresses and secretes human Aß1-42. This secreted Aß forms aggregates in two distinct places within the extracellular matrix. In a screen for extracellular human Aß aggregation regulators, we identified different collagens to ameliorate or potentiate Aß aggregation. We show that a disintegrin and metalloprotease a disintegrin and metalloprotease 2 (ADM-2), an ortholog of ADAM9, reduces the load of extracellular Aß aggregates. ADM-2 is required and sufficient to remove the extracellular Aß aggregates. Thus, we provide in vivo evidence of collagens essential for aggregate formation and metalloprotease participating in extracellular Aß aggregate removal.

The Benchtop mesoSPIM: a next-generation open-source light-sheet microscope for large cleared samples.

In 2015, we launched the mesoSPIM initiative (www.mesospim.org), an open-source project for making light-sheet microscopy of large cleared tissues more accessible. Meanwhile, the demand for imaging larger samples at higher speed and resolution has increased, requiring major improvements in the capabilities of light-sheet microscopy. Here, we introduce the next-generation mesoSPIM ("Benchtop") with significantly increased field of view, improved resolution, higher throughput, more affordable cost and simpler assembly compared to the original version. We developed a new method for testing objectives, enabling us to select detection objectives optimal for light-sheet imaging with large-sensor sCMOS cameras. The new mesoSPIM achieves high spatial resolution (1.5 µm laterally, 3.3 µm axially) across the entire field of view, a magnification up to 20x, and supports sample sizes ranging from sub-mm up to several centimetres, while being compatible with multiple clearing techniques. The new microscope serves a broad range of applications in neuroscience, developmental biology, and even physics.

Too bright for 2 dimensions: recent progress in advanced 3-dimensional microscopy of the kidney.

The kidney is a structurally and functionally complex organ responsible for the control of water, ion, and other solute homeostasis. Moreover, the kidneys excrete metabolic waste products and produce hormones, such as renin and erythropoietin. The functional unit of the kidney is the nephron, which is composed by a serial arrangement of a filter unit called the renal corpuscle and several tubular segments that modulate the filtered fluid by reabsorption and secretion. Within each kidney, thousands of nephrons are closely intermingled and surrounded by an intricate network of blood vessels and various interstitial cell types, including fibroblasts and immune cells. This complex tissue architecture is essential for proper kidney function. In fact, kidney disease is often reflected or even caused by a derangement of the histologic structures. Frequently, kidney histology is studied using microscopic analysis of 2-dimensional tissue sections, which, however, misses important 3-dimensional spatial information. Reconstruction of serial sections tries to overcome this limitation, but is technically challenging, time-consuming, and often inherently linked to sectioning artifacts. In recent years, advances in tissue preparation (e.g., optical clearing) and new light- and electron-microscopic methods have provided novel avenues for 3-dimensional kidney imaging. Combined with novel machine-learning algorithms, these approaches offer unprecedented options for large-scale and automated analysis of kidney structure and function. This review provides a brief overview of these emerging imaging technologies and presents key examples of how these approaches are already used to study the normal and the diseased kidney.

ER-misfolded proteins become sequestered with mitochondria and impair mitochondrial function.

Proteostasis is a challenge for cellular organisms, as all known protein synthesis machineries are error-prone. Here we show by cell fractionation and microscopy studies that misfolded proteins formed in the endoplasmic reticulum can become associated with and partly transported into mitochondria, resulting in impaired mitochondrial function. Blocking the endoplasmic reticulum-mitochondria encounter structure (ERMES), but not the mitochondrial sorting and assembly machinery (SAM) or the mitochondrial surveillance pathway components Msp1 and Vms1, abrogated mitochondrial sequestration of ER-misfolded proteins. We term this mitochondria-associated proteostatic mechanism for ER-misfolded proteins ERAMS (ER-associated mitochondrial sequestration). We testify to the relevance of this pathway by using mutant α-1-antitrypsin as an example of a human disease-related misfolded ER protein, and we hypothesize that ERAMS plays a role in pathological features such as mitochondrial dysfunction.

Characterization of Deposits in Calcific Tendinitis of the Shoulder: Deposits Are Composed of Large Aggregates of Highly Crystalline, Rod-Like Crystals.

BACKGROUND: In the current literature, deposits in calcific tendinitis are described as amorphous masses of hydroxyapatite with a size in the range of 5 to 20 µm. Theoretically, these are too big to be phagocytized by macrophages and induce an inflammatory reaction. PURPOSE: To better characterize the deposits seen in calcific tendinitis. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Included in the study were 6 patients with a history of at least 1 year of shoulder pain (range, 1-14 years). Shoulder arthroscopy was performed under general anesthesia, and calcium deposits from the supraspinatus tendon and biopsies from the adjacent subacromial bursa were taken. Samples were analyzed by light microscopy and immunostained for macrophages. Scanning electron microscopy and energy-dispersive x-ray (EDX) analysis were used to assess the morphology and chemical composition of the calcific deposits. RESULTS: Light microscopy showed round and bulky calcium deposits partially surrounded by activated CD68-positive macrophages within inflammatory tissue. Some hemosiderin positive mononuclear cells, indicative for (micro-) hemorrhage, were seen. Scanning electron microscopy revealed that the large calcific deposits (1-20 µm) were composed of rod-like structures. These highly crystalline rods had a size of approximately 100 nm in length and 20 nm in width. Chemical composition by EDX analysis showed that crystals were composed of mainly calcium, oxygen, and phosphorus, equaling the chemical composition of hydroxyapatite. CONCLUSION: Deposits in calcific tendinitis of the rotator cuff are not amorphous but composed of highly crystalline structures. Fragmentation of these aggregates and subsequent release of the needle-like nanocrystals might initiate the strong inflammatory reaction often seen in patients with calcifying tendinitis of the rotator cuff.

Porcine Circovirus Type 2 Pathogenicity Alters Host's Central Tolerance for Propagation.

Porcine circovirus type 2 (PCV2) infections and resulting diseases are a worldwide threat to pig production. PCV2 bears a uniqueness that allows for us to understand more about chronic infections and the immune system in general. The virus can be phylogenetically subdivided into PCV2a to PCV2h genotypes. Although vaccination against PCV2 has been seen to prevent the manifestation of PCV disease, PCV2 still lingers as subclinical infections in all developmental stages of pigs. The "slow and low" tactic gives PCV2 a particular advantage in a host's immune surveillance. Since the inception of the PCV2 associated panzootic, research scientists have been trying to understand the pathogenicity of PCV2. Different research groups found that one genotype group member was more pathogenic than others. We found, in our weaner infection model with in vivo transfection of different recombinant PCV2 genotype group members that these viruses alter T cell maturation in the thymus, including host's central tolerance. Here, we extend these original observations by showing that PCV2 infected cells were also found in proximity within the female and male reproductive organs of stillborn pig fetuses. These PCV2 pools were sufficient in infecting three and half-day-old embryos in sows. Furthermore, the dominant PCV2 group member was more pathogenic in our weaner infection model. PCV2 pre-immunocompetence infection makes PCV2 recognized by central immune tolerance as belonging to the host. This also explains why pathogenicity is not a genetically intrinsic characteristic of PCV2; however, the dominance of any one PCV2 genotype group member leads to a more efficient deletion of the T cells against that specific genotype group member in the thymus.

Gastric ulcer due to mucormycosis in a critical patient.

We have read the article published by Sánchez-Velázquez P et al., which described a clinical case of gastrointestinal hemorrhage secondary to gastric ulcer due to Mucor. We present a similar clinical case, as an example of one identified by gastroscopy. The case was a 71-year-old female with multiple organ failure secondary to nosocomial pneumonia who required mechanical ventilation, vasoactive drugs, corticosteroids, antibiotherapy and continuous venovenous hemofiltration. Her room was adjacent to a building under construction. The patient had severe upper gastrointestinal bleeding and therefore, an urgent upper gastrointestinal endoscopy was performed. A small amount of blood was identified, as well as a large ulcer without a white base extending from the fundus to the antrum region of the stomach, with bleeding due to rubbing and nodular edges that suggested degeneration.

Recurrent small-bowel bleeding from a Dieulafoy's lesion after combined endoscopic treatment.

INTRODUCTION: Dieulafoy's lesion of the small bowel is an uncommon cause of gastrointestinal (GI) bleeding that often recurs after endoscopic treatment. MATERIAL AND METHODS: we report an observational, descriptive, retrospective, single-center study in 15 patients with small bowel bleeding who were diagnosed with a Dieulafoy's lesion by capsule endoscopy or double-balloon enteroscopy. RESULTS AND CONCLUSIONS: all patients underwent combined endoscopic treatment. During a median follow-up of 33.5 months (range, 2-145), three of the 12 cases that stayed in follow-up (25 %) recurred, all within 48 hours after treatment. Two were successfully re-treated with a repeat endoscopic procedure.

The rebleeding rate in patients evaluated for obscure gastrointestinal bleeding after negative small bowel findings by device assisted enteroscopy.

BACKGROUND: data on the long-term outcome of patients with obscure gastrointestinal bleeding (OGIB) with positive small bowel findings in capsule endoscopy but negative small bowel findings in device-assisted enteroscopy are scarce. OBJECTIVE: this study aimed to evaluate the rebleeding rate and time to rebleed in patients with no small bowel findings in enteroscopy, after a positive capsule endoscopy in the setting of OGIB. Baseline predictors for rebleeding were assessed. METHODS: a retrospective double-center study was performed, including patients with OGIB with positive findings by capsule endoscopy and negative small bowel findings by enteroscopy. RESULTS: thirty-five patients were included. Rebleeding occurred in 40 % of patients during a median follow-up of 27 months. Further evaluation in patients with a rebleed was performed in 85.7 %, leading to a final diagnosis in 78.6 %. The rebleeding rate increased progressively over time, from 17.2 % at one month to 54.4 % at four years. Overt bleeding at the time of the first episode was a predictor of rebleeding (p = 0.03) according to the multivariate analysis. This was 50 % at one year compared with 21.8 % in patients with occult bleeding on admission. CONCLUSIONS: in obscure gastrointestinal bleeding, long-term follow-up and further evaluation may be considered after a positive capsule endoscopy. Even if there are no small bowel findings by device-assisted enteroscopy. The rebleeding rate in our study was 40 %, mainly in the presence of an overt bleeding on admission.

Rhabdoid cavitated adenocarcinoma in the jejunum, an exceptional case by enteroscopy.

We have read the article published by Abdulkader I et al., which described two cases of a rhabdoid tumor of the small bowel diagnosed by surgery. We present a similar case in the jejunum diagnosed by double balloon enteroscopy (DBE). We present the case of a 64-year-old patient with multifactorial anemia and transfusional requirements and a flat lesion of 2 cm in the colon, which showed undifferentiated adenocarcinoma on histopathological analysis.

Transgenic zebrafish modeling low-molecular-weight proteinuria and lysosomal storage diseases.

Epithelial cells lining the proximal tubule of the kidney reabsorb and metabolize most of the filtered low-molecular-weight proteins through receptor-mediated endocytosis and lysosomal processing. Congenital and acquired dysfunctions of the proximal tubule are consistently reflected by the inappropriate loss of solutes including low-molecular-weight proteins in the urine. The zebrafish pronephros shares individual functional segments with the human nephron, including lrp2a/megalin-dependent endocytic transport processes of the proximal tubule. Although the zebrafish has been used as a model organism for toxicological studies and drug discovery, there is no available assay that allows large-scale assessment of proximal tubule function in larval or adult stages. Here we establish a transgenic Tg(lfabp::½vdbp-mCherry) zebrafish line expressing in the liver the N-terminal region of vitamin D-binding protein coupled to the acid-insensitive, red monomeric fluorescent protein mCherry (½vdbp-mCherry). This low-molecular-weight protein construct is secreted into the bloodstream, filtered through the glomerulus, reabsorbed by receptor-mediated endocytosis and processed in the lysosomes of proximal tubule cells of the fish. Thus, our proof-of-concept studies using zebrafish larvae knockout for lrp2a and clcn7 or exposed to known nephrotoxins (gentamicin and cisplatin) demonstrate that this transgenic line is useful to monitor low-molecular-weight proteinuria and lysosomal processing. This represents a powerful new model organism for drug screening and studies of nephrotoxicity.

A degenerate Todani Ia choledochal cyst in a patient with pancreas divisum.

Bile duct cysts represent congenital abnormalities associated with biliopancreatic maljunction that may undergo malignant degeneration. We report herein the case of a 72-year-old male patient with cholangitis. MR-cholangiography and abdominal CT revealed a mass at the biliary-pancreatic-duodenal crossroads, extrahepatic biliary dilation up to 38 mm, and pancreas divisum. Gastroscopy found an infiltrative bulbar mucosa with adenocarcinoma in biopsy samples, and extrinsic bulging of the second duodenal portion. Endoscopic ultrasound showed a choledochal cystic dilation with solid contents, and FNA findings were nonspecific. ERCP confirmed an adenomatous papilla at the lower portion of the extrinsic formation, and a large cystic, saccular dilation of extrahepatic bile ducts (Todani Ia). Fistulotomy was required for deep cannulation of the proximal biliary tract, and attention was drawn to extruding polypoid lesions originating in the biliary epithelium, identified in biopsies as adenoma with dysplasia. Finally, a diagnosis was made of advanced adenocarcinoma in choledochal cyst.

Direct imaging of uncoated biological samples enables correlation of super-resolution and electron microscopy data.

A simple method for imaging biological tissue samples by electron microscopy and its correlation with super-resolution light microscopy is presented. This room temperature protocol, based on protecting thin biological specimens with methylcellulose and imaging with low voltage scanning electron microscopy, circumvents complex classical electron microscopy sample preparation steps requiring dehydration, resin embedding and use of contrast agents. This technique facilitates visualization of subcellular structures e.g. synaptic clefts and synaptic vesicles in mouse brain tissue and the organization of mitochondrial cristae in the zebrafish retina. Application of immunogold protocols to these samples can determine the precise localization of synaptic proteins and, in combination with super-resolution light microscopy methods clearly pinpoints the subcellular distribution of several proteins in the tissue. The simplicity of the method, including section collection on a silicon wafer, reduces artefacts and correlates protein location with sample morphology.

Humanismo y pediatría en el siglo XXI / Humanism and pediatrics in the 21st century

Contenido: Qué es el humanismo. Precursores del humanismo literario. Humanistas célebres del mundo. Elogio de la pediatría y los pediatras. Una opción preventiva preferencial. Ideas para mejorar el bienestar de niños, niñas y adolescentes. Personalidades del humanismo argentino ineludibles. Humanistas platenses destacados. Abuelidad humanizante

Plasticity Related Gene 3 (PRG3) overcomes myelin-associated growth inhibition and promotes functional recovery after spinal cord injury.

The Plasticity Related Gene family covers five, brain-specific, transmembrane proteins (PRG1-5, also termed LPPR1-5) that operate in neuronal plasticity during development, aging and brain trauma. Here we investigated the role of the PRG family on axonal and filopodia outgrowth. Comparative analysis revealed the strongest outgrowth induced by PRG3 (LPPR1). During development, PRG3 is ubiquitously located at the tip of neuronal processes and at the plasma membrane and declines with age. In utero electroporation of PRG3 induced dendritic protrusions and accelerated spine formations in cortical pyramidal neurons. The neurite growth promoting activity of PRG3 requires RasGRF1 (RasGEF1/Cdc25) mediated downstream signaling. Moreover, in axon collapse assays, PRG3-induced neurites resisted growth inhibitors such as myelin, Nogo-A (Reticulon/RTN-4), thrombin and LPA and impeded the RhoA-Rock-PIP5K induced neurite repulsion. Transgenic adult mice with constitutive PRG3 expression displayed strong axonal sprouting distal to a spinal cord lesion. Moreover, fostered PRG3 expression promoted complex motor-behavioral recovery compared to wild type controls as revealed in the Schnell swim test (SST). Thus, PRG3 emerges as a developmental RasGRF1-dependent conductor of filopodia formation and axonal growth enhancer. PRG3-induced neurites resist brain injury-associated outgrowth inhibitors and contribute to functional recovery after spinal cord lesions. Here, we provide evidence that PRG3 operates as an essential neuronal growth promoter in the nervous system. Maintaining PRG3 expression in aging brain may turn back the developmental clock for neuronal regeneration and plasticity.

Topographic contrast of ultrathin cryo-sections for correlative super-resolution light and electron microscopy.

Fluorescence microscopy reveals molecular expression at nanometer resolution but lacks ultrastructural context information. This deficit often hinders a clear interpretation of results. Electron microscopy provides this contextual subcellular detail, but protein identification can often be problematic. Correlative light and electron microscopy produces complimentary information that expands our knowledge of protein expression in cells and tissue. Inherent methodological difficulties are however encountered when combining these two very different microscopy technologies. We present a quick, simple and reproducible method for protein localization by conventional and super-resolution light microscopy combined with platinum shadowing and scanning electron microscopy to obtain topographic contrast from the surface of ultrathin cryo-sections. We demonstrate protein distribution at nuclear pores and at mitochondrial and plasma membranes in the extended topographical landscape of tissue.