Hematopoietic Stem Cell Niches Produce Lineage-Instructive Signals to Control Multipotent Progenitor Differentiation.

Hematopoietic stem cells (HSCs) self-renew in bone marrow niches formed by mesenchymal progenitors and endothelial cells expressing the chemokine CXCL12, but whether a separate niche instructs multipotent progenitor (MPP) differentiation remains unclear. We show that MPPs resided in HSC niches, where they encountered lineage-instructive differentiation signals. Conditional deletion of the chemokine receptor CXCR4 in MPPs reduced differentiation into common lymphoid progenitors (CLPs), which decreased lymphopoiesis. CXCR4 was required for CLP positioning near Interleukin-7+ (IL-7) cells and for optimal IL-7 receptor signaling. IL-7+ cells expressed CXCL12 and the cytokine SCF, were mesenchymal progenitors capable of differentiation into osteoblasts and adipocytes, and comprised a minor subset of sinusoidal endothelial cells. Conditional Il7 deletion in mesenchymal progenitors reduced B-lineage committed CLPs, while conditional Cxcl12 or Scf deletion from IL-7+ cells reduced HSC and MPP numbers. Thus, HSC maintenance and multilineage differentiation are distinct cell lineage decisions that are both controlled by HSC niches.

Esophagomediastinal fistula: a rare case of gastrointestinal tuberculosis.

A 40-year-old male with history of HIV infection was admitted to the hospital with a one-month history of productive cough, vespertine fever, night sweats, loss of appetite and unintentional 10-Kg weight loss. Physical exam was remarkable for cachexia. Blood tests revealed a CD4+ T lymphocyte count of 23 cells/mm3 and HIV viral load of 837,678 copies/ml. Bacilloscopies were positive. Chest computed thomography (CT) showed multiple mediastinal lymph nodes, signs of esophagomediastinal fistula, pericardial effusion and multiple micronodular pulmonary opacities. Endoscopy (EGD) revealed a 10 mm deep ulcer-like lesion in the middle esophagus with pus overflow, but no bubbles were seen. The diagnosis of stage C3 HIV infection with disseminated tuberculosis was made and the patient underwent standard antituberculosis (RIPE) and antiretroviral therapy. Given the mediastinitis risk a percutaneous endoscopic gastrostomy (PEG) tube was placed for nutritional purposes.

When needles are not enough, forceps delivers!

A 35-year-old male with a history of recurrent pleuritic chest pain was referred for evaluation of a mediastinal mass detected on CT. MRI showed a 10.5 x 7 x 3 cm lesion in the posterior mediastinum. EUS revealed a multicystic lesion with thin septa and clear anechoic content that extended from the lower posterior mediastinum to the upper retroperitoneum. EUS-FNA was performed using a 22-gauge needle with aspiration of a serosanguineous fluid. Fluid analysis showed low values of amylase, triglycerides, CEA, and CA19-9. Cytology tests identified small mature lymphocytes without malignancy.

Topflight endoscopic submucosal dissection: a novel strategy for the resection of gastric fundus tumors.

Video 1Resection of a gastric lesion using Topflight ESD.

Cell circuits between leukemic cells and mesenchymal stem cells block lymphopoiesis by activating lymphotoxin beta receptor signaling.

Acute lymphoblastic and myeloblastic leukemias (ALL and AML) have been known to modify the bone marrow microenvironment and disrupt non-malignant hematopoiesis. However, the molecular mechanisms driving these alterations remain poorly defined. Using mouse models of ALL and AML, here we show that leukemic cells turn off lymphopoiesis and erythropoiesis shortly after colonizing the bone marrow. ALL and AML cells express lymphotoxin α1ß2 and activate lymphotoxin beta receptor (LTßR) signaling in mesenchymal stem cells (MSCs), which turns off IL7 production and prevents non-malignant lymphopoiesis. We show that the DNA damage response pathway and CXCR4 signaling promote lymphotoxin α1ß2 expression in leukemic cells. Genetic or pharmacological disruption of LTßR signaling in MSCs restores lymphopoiesis but not erythropoiesis, reduces leukemic cell growth, and significantly extends the survival of transplant recipients. Similarly, CXCR4 blocking also prevents leukemia-induced IL7 downregulation and inhibits leukemia growth. These studies demonstrate that acute leukemias exploit physiological mechanisms governing hematopoietic output as a strategy for gaining competitive advantage.

Spatiotemporal dynamics of cytokines expression dictate fetal liver hematopoiesis.

During embryogenesis, yolk-sac and intra-embryonic-derived hematopoietic progenitors, comprising the precursors of adult hematopoietic stem cells, converge into the fetal liver. With a new staining strategy, we defined all non-hematopoietic components of the fetal liver and found that hepatoblasts are the major producers of hematopoietic growth factors. We identified mesothelial cells, a novel component of the stromal compartment, producing Kit ligand, a major hematopoietic cytokine. A high-definition imaging dataset analyzed using a deep-learning based pipeline allowed the unambiguous identification of hematopoietic and stromal populations, and enabled determining a neighboring network composition, at the single cell resolution. Throughout active hematopoiesis, progenitors preferentially associate with hepatoblasts, but not with stellate or endothelial cells. We found that, unlike yolk sac-derived progenitors, intra-embryonic progenitors respond to a chemokine gradient created by CXCL12-producing stellate cells. These results revealed that FL hematopoiesis is a spatiotemporal dynamic process, defined by an environment characterized by low cytokine concentrations.

CpG inhibits pro-B cell expansion through a cathepsin B-dependent mechanism.

TLR9 is expressed in cells of the innate immune system, as well as in B lymphocytes and their progenitors. We investigated the effect of the TLR9 ligand CpG DNA on the proliferation of pro-B cells. CpG DNA inhibits the proliferation of pro-B, but not pre-B, cells by inducing caspase-independent cell death through a pathway that requires the expression of cathepsin B. This pathway is operative in Rag-deficient mice carrying an SP6 transgene, in which B lymphopoiesis is compromised, to reduce the size of the B lymphocyte precursor compartments in the bone marrow. Thus, TLR9 signals can regulate B lymphopoiesis in vivo.

Endometriosis-Related Spontaneous Hemoperitoneum in the Third Trimester: A Case Report.

Spontaneous hemoperitoneum in pregnancy (SHiP) is a rare but significant condition in pregnancy and is linked to high rates of morbidity and mortality. Endometriosis increases the risk of SHiP, particularly during the third trimester of pregnancy. We report a case of a 45-year-old woman in the third trimester of a pregnancy complicated by SHiP due to the rupture of a uterine artery by an endometriosis implant, which is a particularly rare cause.

Fetal Deaths in SARS-CoV-2-Infected Pregnant Women: A Portuguese Case Series.

Introduction: Stillbirth has been documented as an outcome of SARS-CoV-2 infection in pregnancy. Placental hypoperfusion and inflammation secondary to maternal immune response seem to play a role in the cascade of events that contribute to fetal death. The aim of our study is to report a perinatal outcome of SARS-CoV-2 infection in pregnancy adding information to the pool of data on COVID-19 pregnancy outcomes. Case Presentation. This is the first stillbirth case series occurring in pregnant women infected with SARS-CoV-2 in a Portuguese cohort. Between April 2020 and March 2021, we had 2680 births in our centre, of which 130 (4.95%) involved mothers infected with SARS-CoV-2. Of total births, there were 14 stillbirths (0.52%), accounting for the highest stillbirth rate we have had in the last 5 years. Among these 14 stillbirths, 5 (35.71%) occurred in SARS-CoV-2-infected mothers. We report the clinical features and placental histopathologic findings of 4 stillbirth cases that occurred in our hospital. Discussion. The stillbirth rate among SARS-CoV-2-infected pregnant women (5/130; 3.84%) was significantly increased compared to noninfected patients (9/2550; 0.35%). Most women (3/4) were asymptomatic for COVID-19, a surprising outcome, given the current literature. All cases had histologic exams showing placental signs of vascular malperfusion, although we acknowledge that 3/5 had obstetric conditions related to placental vascular impairment such as preeclampsia and HELLP syndrome. Conclusion: Stillbirth can be a perinatal consequence of SARS-CoV-2 infection in pregnancy, even in asymptomatic patients. We urge more studies to explore the association between SARS-CoV-2 infection and the risk of stillbirth.

Bioinformatic analyses to uncover genes involved in trehalose metabolism in the polyploid sugarcane.

Trehalose-6-phosphate (T6P) is an intermediate of trehalose biosynthesis that plays an essential role in plant metabolism and development. Here, we comprehensively analyzed sequences from enzymes of trehalose metabolism in sugarcane, one of the main crops used for bioenergy production. We identified protein domains, phylogeny, and in silico expression levels for all classes of enzymes. However, post-translational modifications and residues involved in catalysis and substrate binding were analyzed only in trehalose-6-phosphate synthase (TPS) sequences. We retrieved 71 putative full-length TPS, 93 trehalose-6-phosphate phosphatase (TPP), and 3 trehalase (TRE) of sugarcane, showing all their conserved domains, respectively. Putative TPS (Classes I and II) and TPP sugarcane sequences were categorized into well-known groups reported in the literature. We measured the expression levels of the sequences from one sugarcane leaf transcriptomic dataset. Furthermore, TPS Class I has specific N-glycosylation sites inserted in conserved motifs and carries catalytic and binding residues in its TPS domain. Some of these residues are mutated in TPS Class II members, which implies loss of enzyme activity. Our approach retrieved many homo(eo)logous sequences for genes involved in trehalose metabolism, paving the way to discover the role of T6P signaling in sugarcane.

Finding the right niche: B-cell migration in the early phases of T-dependent antibody responses.

Humoral immune responses depend on B cells encountering antigen, interacting with helper T cells, proliferating and differentiating into low-affinity plasma cells or, after organizing into a germinal center (GC), high-affinity plasma cells and memory B cells. Remarkably, each of these events occurs in association with distinct stromal cells in separate subcompartments of the lymphoid tissue. B cells must migrate from niche to niche in a rapid and highly regulated manner to successfully mount a response. The chemokine, CXCL13, plays a central role in guiding B cells to follicles whereas T-zone chemokines guide activated B cells to the T zone. Sphingosine-1-phosphate (S1P) promotes cell egress from the tissue, as well as marginal-zone B-cell positioning in the spleen. Recent studies have identified a role for the orphan receptor, EBV-induced molecule 2 (EBI2; GPR183), in guiding activated B cells to inter and outer follicular niche(s) and down-regulation of this receptor is essential for organizing cells into GCs. In this review, we discuss current understanding of the roles played by chemokines, S1P and EBI2 in the migration events that underlie humoral immune responses.

Factors associated with mental health and quality of life during the COVID-19 pandemic in Brazil.

BACKGROUND: Although mental distress and quality of life (QoL) impairments because of the pandemic have increased worldwide, the way that each community has been affected has varied. AIMS: This study evaluated the impact of social distancing imposed by coronavirus disease-2019 (COVID-19) on Brazilians' mental health and QoL. METHOD: In this cross-sectional community-based online survey, data from 1156 community-dwelling adults were gathered between 11 May and 3 June 2020. We examined independent correlates of depression, anxiety and QoL, including sociodemographic and clinical characteristics, optimism/pessimism and spiritual/religious coping. Dependent variables were assessed using the 9-item Patient Health Questionnaire for depressive symptoms, the 7-item Generalized Anxiety Disorder Scale for anxiety symptoms, and the World Health Organization Quality of Life-BREF for QoL. Correlates of depressive and anxiety disorder were estimated using logistic regression. RESULTS: There were high levels of depressive symptoms (41.9%) and anxiety symptoms (29.0%) in participants. Negative spiritual/religious coping was positively correlated with depressive disorder (odds ratio (OR) = 2.14 95% CI 1.63-2.80; P < 0.001) and with anxiety disorder (OR = 2.46 95% CI 1.90-3.18; P < 0.001), and associated with worse social and environmental QoL (P < 0.001). Healthcare professionals were less likely to have depressive symptoms (OR = 0.71, 95% CI 0.55-0.93; P < 0.001). Participants with friend/family with COVID-19 scored lower on psychological and environmental QoL (P < 0.05). Participants with a longer duration of social isolation were less likely to experience anxiety disorder (OR = 0.99, 95% CI 0.98-0.99; P = 0.004). CONCLUSIONS: We found high levels of depressive and anxiety symptoms and low levels of QoL in Brazil, which has become a pandemic epicentre. Several characteristics were associated with negative mental health symptoms in this study. This information may contribute to local health policies in dealing with the mental health consequences of COVID-19.

Bleeding Disorders in Bothrops atrox Envenomations in the Brazilian Amazon: Participation of Hemostatic Factors and the Impact of Tissue Factor.

Bleeding is a common hemostatic disorder that occurs in Bothrops envenomations. We evaluated the changes in coagulation, fibrinolysis components, and platelets in Bothrops atrox envenomations with bleeding. This is an observational study with B. atrox snakebite patients (n = 100) treated in Manaus, Brazilian Amazon. Bleeding was recorded on admission and during hospitalization. We found that the platelet count in our patients presented a weak correlation to tissue factor, factor II, and plasminogen. Tissue factor presented weak correlation to factor V, II, D-dimer, plasminogen, alpha 2-antiplasmin, and moderate correlation to fibrinogen and fibrin/fibrinogen degradation product (FDP). Patients with systemic bleeding (n = 20) presented low levels of factor V, II, fibrinogen, plasminogen, and alpha 2-antiplasmin, and high levels of tissue factor and FDP compared to those without bleeding. Patients with only local bleeding (n = 41) and without bleeding showed similar levels of hemostatic factors. Thrombocytopenia was observed mainly in patients with systemic bleeding and increased levels of serum venom. No association was found between venom levels and systemic bleeding, or between venom levels and clinical severity of envenomation. This is the first report that shows the participation of the extrinsic coagulation pathway in the consumption coagulopathy of B. atrox envenomations with systemic bleeding due to tissue factor release.

Bothrops snakebites in the Amazon: recovery from hemostatic disorders after Brazilian antivenom therapy.

Introduction:Bothrops atrox snakebites are a major public health problem in the Amazon region and also cause hemostatic disorders. In this study, we assessed the recovery from hemostatic disorders in Bothrops snakebite patients after being given antivenom therapy.Methods: This is a prospective study of Bothrops snakebite patients (n = 100) treated at the Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazilian Amazon, between January 2016 and December 2017. Blood samples were taken for the measurement of venom concentrations, platelets, clotting time and factors of patients on admission, 12, 24 and 48 h after antivenom therapy, and taken again on discharge. The presence of systemic bleeding was recorded during the follow-up.Results: On admission, systemic bleeding was observed in 14% of the patients. Thrombocytopenia was noted in 10% of the patients. A total of 54% of the patients presented unclottable blood with low levels of fibrinogen and alpha 2-antiplasmin, and high levels of fibrin/fibrinogen degradation product (FDP) and D-dimers. Unclottable blood and systemic bleeding were overcome in most patients 12 h after the antivenom therapy. Three patients developed systemic bleeding 48 h after antivenom therapy. Levels of fibrinogen and alpha 2-antiplasmin, FDP and D-dimer returned to normal around 48 h after the treatment or on discharge. The frequency of thrombocytopenia with high mean platelet volume increased in the first 24 h after antivenom therapy, and decreased on discharge. Bothrops venom levels in patients decreased 12 h after antivenom therapy and were not correlated with coagulation and fibrinolytic parameters. There were no deaths.Conclusion: Laboratorial parameters of coagulopathy returned to normal values within 48 h after the antivenom therapy until discharge. A few patients still presented bleeding signs within 48 h after beginning antivenom therapy. However, the Brazilian antivenom was able to overcome the hemostatic disorders in these cases of envenomation.

"Bad things come in small packages": predicting venom-induced coagulopathy in Bothrops atrox bites using snake ontogenetic parameters.

Introduction: Snake venom composition shows significant inter- and intra-species variation. In the case of the viperid species Bothrops atrox, responsible for the majority of snakebites in the Amazon region, geographical and ontogenetic variables affect venom composition, with ecological and medical implications. Previous studies had shown that venom from neonate and juvenile Bothrops specimens have a higher in vitro coagulant activity. The aim of this investigation was to assess the association of clinical outcomes, such as venom-induced coagulopathy and local complications, with B. atrox ontogenetic variables.Methods: This study explored the relationship between some clinical parameters in patients suffering envenomations by B. atrox in the Amazon and several morphometric parameters of the snake specimens causing the bites.Results: There were 248 specimens confirmed as agents of envenomation, mostly female snakes (70.5%) and classified as juveniles (62.7%). Patients bitten by neonates compared to adult snakes [OR = 2.70 (95%CI 1.15-6.37); p = .021] and by snakes with white tail tip [OR = 1.98 (95%CI 1.15-3.41); p = .013] were more likely to develop coagulopathy. Time from patient admission to the unclottable blood reversion was not affected by the snake gender (p = .214) or age (p = .254). Patients bitten by neonate (p = .024) or juvenile snakes (p < .0001) presented a lower frequency of moderate to severe edema, as compared to those bitten by adult snakes. In agreement with experimental observations, patients bitten by neonates and by snakes with a white tail tip were more likely to develop coagulopathy than those bitten by adult snakes. In contrast, envenomations by adult snakes were associated with a higher incidence of severe local edema.Conclusion: Despite these variations, no difference was observed in the time needed to recover blood clotting in these patients after Bothrops antivenom administration.

Factors Associated with Systemic Bleeding in Bothrops Envenomation in a Tertiary Hospital in the Brazilian Amazon.

Bothrops snakebites usually present systemic bleeding, and the clinical⁻epidemiological and laboratorial factors associated with the development of this manifestation are not well established. In this study, we assessed the prevalence of Bothrops snakebites with systemic bleeding reported at the Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, in Manaus, Amazonas State, Brazil, and the clinical⁻epidemiological and laboratorial factors associated with systemic bleeding. This is an observational, cross-sectional study carried out between August, 2013 and July, 2016. Patients who developed systemic bleeding on admission or during hospitalization were considered cases, and those with non-systemic bleeding were included in the control group. Systemic bleeding was observed in 63 (15.3%) of the 442 Bothrops snakebites evaluated. Bothrops snakebites mostly occurred in males (78.2%), in rural areas (89.0%) and in the age group of 11 to 30 years old (40.4%). It took most of the patients (59.8%) less than 3 h to receive medical assistance. Unclottable blood (AOR = 3.11 (95% CI = 1.53 to 6.31; p = 0.002)) and thrombocytopenia (AOR = 4.52 (95% CI = 2.03 to 10.09; p < 0.001)) on admission were independently associated with systemic bleeding during hospitalization. These hemostatic disorders on admission increase the chances of systemic bleeding during hospitalization. Prospective studies are needed to clarify the pathophysiology of systemic bleeding in Bothrops snakebites in the Amazon region.

Autologous transplantation of bone marrow mononuclear stem cells by mini-thoracotomy in dilated cardiomyopathy: technique and early results.

CONTEXT AND OBJECTIVES: There are few studies concerning bone marrow mononuclear cell (BMMC) transplantation in cases of nonischemic dilated cardiomyopathy. This study describes a novel technique of BMMC transplantation and the results up to one year after the procedure. DESIGN AND SETTING: This was a case series to evaluate the safety and viability of the procedure, at Instituto de Cardiologia do Rio Grande do Sul. METHODS: Nine patients with symptomatic dilated cardiomyopathy, functional class III/IV and left ventricular ejection fraction (LVEF) < 35% received BMMC (9.6 +/- 2.6 x 107 cells) at 20 sites in the ventricular wall, by means of thoracotomy of length 5 cm in the fifth left intercostal space. Echocardiograms and nuclear magnetic resonance (NMR) were performed. RESULTS: There were no major complications. The functional class results for the first six patients (preoperatively and at two, four, eight and twelve-month follow-ups, respectively) were: [IV-2, III-4] to [I-5, II-1] to [I-3, II-3] to [I-2, II-3] and [I-2, II-3]. Echocardiograms showed LVEF: 25.9 +/- 8.2; 32.9 +/- 10.4; 29.4 +/- 7.2; 25.1 +/- 7.9; 25.4 +/- 6.8% (p = 0.023); and % left ventricular (LV) fiber shortening: 12.6 +/- 4.4; 16.4 +/- 5.4; 14.3 +/- 3.7; 12.1 +/- 4.0; 12.2 +/- 3.4% (p = 0.021). LV performance variation seen on NMR was non-significant. CONCLUSION: Intramyocardial transplantation of BMMC in dilated cardiomyopathy cases is feasible and safe. There were early improvements in symptoms and LV performance. Medium-term evaluation revealed regression of LV function, although maintaining improved functional class.