The genome of the black-footed cat: Revealing a rich natural history and urgent conservation priorities for small felids.

Habitat degradation and loss of genetic diversity are common threats faced by almost all of today's wild cats. Big cats, such as tigers and lions, are of great concern and have received considerable conservation attention through policies and international actions. However, knowledge of and conservation actions for small wild cats are lagging considerably behind. The black-footed cat, Felis nigripes, one of the smallest felid species, is experiencing increasing threats with a rapid reduction in population size. However, there is a lack of genetic information to assist in developing effective conservation actions. A de novo assembly of a high-quality chromosome-level reference genome of the black-footed cat was made, and comparative genomics and population genomics analyses were carried out. These analyses revealed that the most significant genetic changes in the evolution of the black-footed cat are the rapid evolution of sensory and metabolic-related genes, reflecting genetic adaptations to its characteristic nocturnal hunting and a high metabolic rate. Genomes of the black-footed cat exhibit a high level of inbreeding, especially for signals of recent inbreeding events, which suggest that they may have experienced severe genetic isolation caused by habitat fragmentation. More importantly, inbreeding associated with two deleterious mutated genes may exacerbate the risk of amyloidosis, the dominant disease that causes mortality of about 70% of captive individuals. Our research provides comprehensive documentation of the evolutionary history of the black-footed cat and suggests that there is an urgent need to investigate genomic variations of small felids worldwide to support effective conservation actions.

N-cadherin cleavage: A critical function that induces diabetic retinopathy fibrosis via regulation of ß-catenin translocation.

Retinal fibrosis is a severe pathological change in the late stage of diabetic retinopathy and is also the leading cause of blindness. We have previously revealed that N-cadherin was significantly increased in type 1 and type 2 diabetic mice retinas and the fibrovascular membranes from proliferative diabetic retinopathy (PDR) patients. However, whether N-cadherin directly induces retinal fibrosis in DR and the related mechanism is unknown. Here, we investigated the pathogenic role of N-cadherin in mediating retinal fibrosis and further explored the relevant therapeutic targets. We found that the level of N-cadherin was significantly increased in PDR patients and STZ-induced diabetic mice and positively correlated with the fibrotic molecules Connective Tissue Growth Factor (CTGF) and fibronectin (FN). Moreover, intravitreal injection of N-cadherin adenovirus significantly increased the expression of FN and CTGF in normal mice retinas. Mechanistically, overexpression of N-cadherin promotes N-cadherin cleavage, and N-cadherin cleavage can further induce translocation of non-p-ß-catenin in the nucleus and upregulation of fibrotic molecules. Furthermore, we found a novel N-cadherin cleavage inhibitor, pigment epithelial-derived factor (PEDF), which ameliorated the N-cadherin cleavage and subsequent retinal fibrosis in diabetic mice. Thus, our findings provide novel evidence that elevated N-cadherin level not only acts as a classic EMT maker but also plays a causative role in diabetic retinal fibrosis, and targeting N-cadherin cleavage may provide a strategy to inhibit retinal fibrosis in DR patients.

Family intimacy and adaptability and non-suicidal self-injury: a mediation analysis.

BACKGROUND: Current research has been focusing on non-suicidal self-injury (NSSI) behaviors among adolescents with depression. Although family intimacy and adaptability are considered protective factors for NSSI, evidence supporting this relationship is lacking. OBJECTIVE: This study aims to examine the mechanisms operating in the relationship between family intimacy and adaptability and NSSI behaviors among adolescents. METHODS: A self-administered general demographic information questionnaire, the Behavioral Functional Assessment Scale for Non-Suicidal Self-Injury, the Family Intimacy and Adaptability Scale, the Connor-Davidson Resilience Scale, and the Self-Assessment of Depression Scale were distributed among adolescents with depression in three tertiary hospitals in Jiangsu Province. RESULTS: The relationship between family intimacy and adaptability and NSSI was assessed among 596 adolescents with depression. The results revealed the following: (1) Family intimacy and adaptability were negatively correlated with NSSI behavior. (2) Psychological resilience and depression levels acted as chain mediators in the relationship between family intimacy and adaptability and NSSI behavior. CONCLUSIONS: Enhancing psychological resilience, controlling depressive symptoms, and reducing depression severity among adolescents by improving their family intimacy and adaptability are conducive to preventing and mitigating their NSSI behaviors.

Cu(II)-Loaded Polydopamine-Coated Urchin-like Titanate Microspheres as a High-Performance IMAC Adsorbent for Hemoglobin Separation.

Immobilized metal ion affinity chromatography (IMAC) adsorbents generally have excellent affinity for histidine-rich proteins. However, the leaching of metal ions from the adsorbent usually affects its adsorption performance, which greatly affects the reusable performance of the adsorbent, resulting in many limitations in practical applications. Herein, a novel IMAC adsorbent, i.e., Cu(II)-loaded polydopamine-coated urchin-like titanate microspheres (Cu-PDA-UTMS), was prepared via metal coordination to make Cu ions uniformly decorate polydopamine-coated titanate microspheres. The as-synthesized microspheres exhibit an urchin-like structure, providing more binding sites for hemoglobin. Cu-PDA-UTMS exhibit favorable selectivity for hemoglobin adsorption and have a desirable adsorption capacity towards hemoglobin up to 2704.6 mg g-1. Using 0.1% CTAB as eluent, the adsorbed hemoglobin was easily eluted with a recovery rate of 86.8%. In addition, Cu-PDA-UTMS shows good reusability up to six cycles. In the end, the adsorption properties by Cu-PDA-UTMS towards hemoglobin from human blood samples were analyzed by SDS-PAGE. The results showed that Cu-PDA-UTMS are a high-performance IMAC adsorbent for hemoglobin separation, which provides a new method for the effective separation and purification of hemoglobin from complex biological samples.

Evolution and lineage dynamics of a transmissible cancer in Tasmanian devils.

Devil facial tumour 1 (DFT1) is a transmissible cancer clone endangering the Tasmanian devil. The expansion of DFT1 across Tasmania has been documented, but little is known of its evolutionary history. We analysed genomes of 648 DFT1 tumours collected throughout the disease range between 2003 and 2018. DFT1 diverged early into five clades, three spreading widely and two failing to persist. One clade has replaced others at several sites, and rates of DFT1 coinfection are high. DFT1 gradually accumulates copy number variants (CNVs), and its telomere lengths are short but constant. Recurrent CNVs reveal genes under positive selection, sites of genome instability, and repeated loss of a small derived chromosome. Cultured DFT1 cell lines have increased CNV frequency and undergo highly reproducible convergent evolution. Overall, DFT1 is a remarkably stable lineage whose genome illustrates how cancer cells adapt to diverse environments and persist in a parasitic niche.

Characterization and genomic analysis of a novel bacteriophage BUCT_49532 lysing Klebsiella pneumoniae.

Bacteriophages are a type of virus widely distributed in nature that demonstrates a remarkable aptitude for selectively recognizing and infecting bacteria. In particular, Klebsiella pneumoniae is acknowledged as a clinical pathogen responsible for nosocomial infections and frequently develops multidrug resistance. Considering the increasing prevalence of antibiotic-resistant bacteria, bacteriophages have emerged as a compelling alternative therapeutic approach. In this study, a novel phage named BUCT_49532 was isolated from sewage using K. pneumoniae K1119 as the host. Electron microscopy revealed that BUCT_49532 belongs to the Caudoviricetes class. Further analysis through whole genome sequencing demonstrated that BUCT_49532 is a Jedunavirus comprised of linear double-stranded DNA with a length of 49,532 bp. Comparative genomics analysis based on average nucleotide identity (ANI) values revealed that BUCT_49532 should be identified as a novel species. Characterized by a good safety profile, high environmental stability, and strong lytic performance, phage BUCT_49532 presents an interesting case for consideration. Although its host range is relatively narrow, its application potential can be expanded by utilizing phage cocktails, making it a promising candidate for biocontrol approaches.

Neutrophil side fluorescence: a new indicator for predicting the severity of patients with bronchiectasis.

BACKGROUND: Neutrophilic inflammation in the airway is a hallmark of bronchiectasis. Neutrophil extracellular traps (NETs) have been reported to play an important role in the occurrence and development of bronchiectasis. Neutrophil side fluorescence is one of the characteristics of neutrophils that can reflect the activation of neutrophils and the formation of NETs. OBJECTIVE: To explore the relationship between the values of neutrophil side fluorescence (NEUT-SFL) in the peripheral blood of bronchiectasis patients, and the severity of the disease. METHODS: 82 patients with bronchiectasis from the Department of Respiratory and Critical Medicine, at the Third Affiliated Hospital of Southern Medical University and were scored with Bronchiectasis Severity Index (BSI) (2019-2021). The clinical data such as the value of NEUT-SFL, neutrophil count, C-reactive protein, and procalcitonin levels were collected and retrospectively analyzed. NEUT-SFL values neutrophil count from 28 healthy subjects were also used to ascertain cut-off values. RESULTS: Based on the BSI scores, patients were divided into three categories as mild (32%), moderate (29%), and severe (39%). Our results showed that the values of NEUT-SFL were higher in bronchiectasis patients compared to healthy controls. The levels of NEUT-SFL positively correlated with the high BSI scores in patients (P = 0.037, r = 0.23) and negatively correlated with the lung function in these patients (r = - 0.35, P = 0.001). The area under the ROC curve was 0.813, the best cut-off was 42.145, indicating that NEUT-SFL values > 42.145 can potentially predict the severity of bronchiectasis. CONCLUSIONS: The values of NEUT-SFL in the peripheral blood can be used for predicting the severity of bronchiectasis.

Diagnostic value of susceptibility-weighted imaging for endometrioma: preliminary results from a retrospective analysis.

BACKGROUND: Endometrioma is a common manifestation of endometriosis that can be difficult to diagnose with conventional magnetic resonance imaging (MRI). Susceptibility-weighted imaging (SWI) may be more sensitive than conventional MRI in the detection of chronic, local hemorrhagic disease. PURPOSE: To investigate whether signal voids in SWI sequences could be used in the preoperative diagnosis of endometrioma. MATERIAL AND METHODS: This retrospective study included consecutive female patients with clinically suspected endometrioma. All patients underwent pelvic 3-T MRI (T1- and T2-weighted) and SWI within two weeks before laparoscopy. Two experienced radiologists blinded to the histopathologic/clinical diagnoses interpreted the images together, and any disagreements were resolved by consensus. RESULTS: The final analysis included 73 patients: 46 patients (mean age=37 years; age range=22-68 years) with 85 endometrioma lesions and 27 patients (mean age=34 years; age range=15-68 years) with 34 non-endometrioid cystic lesions (18 hemorrhagic corpus luteal cysts, three simple cysts, three mucinous cystadenomas, two mature teratomas, and one endometrioid cyst with corpus luteum rupture/hemorrhage). The presenting symptoms for patients with endometrioma were chronic pelvic pain (44.6%), dysmenorrhea (31.9%), infertility (12.8%), dyspareunia (6.4%), and menstrual irregularity (4.3%). MRI identified all 119 lesions observed laparoscopically. SWI visualized punctate or curvilinear signal voids along the cyst wall or within the lesion in 67 of 85 endometriomas (78.8%) and only 3 of 31 non-endometrioid cysts (8.8%). CONCLUSION: The use of SWI to look for signal voids in the cyst wall or within the lesion could facilitate the preoperative diagnosis of endometrioma.

Granulocyte colony-stimulating factor directly acts on mouse lymphoid-biased but not myeloid-biased hematopoietic stem cells.

Granulocyte colony-stimulating factor (G-CSF) is widely used in clinical settings to mobilize hematopoietic stem cells (HSCs) into the circulation for HSC harvesting and transplantation. However, whether G-CSF directly stimulates HSCs to change their cell cycle state and fate is controversial. HSCs are a heterogeneous population consisting of different types of HSCs, such as myeloid-biased HSCs and lymphoid-biased HSCs. We hypothesized that G-CSF has different effects on different types of HSCs. To verify this, we performed serum-free single-cell culture and competitive repopulation with cultured cells. Single highly purified HSCs and hematopoietic progenitor cells (HPCs) were cultured with stem cell factor (SCF), SCF + G-CSF, SCF + granulocyte/macrophage (GM)-CSF, or SCF + thrombopoietin (TPO) for 7 days. Compared with SCF alone, SCF + G-CSF increased the number of divisions of cells from the lymphoid-biased HSC-enriched population but not that of cells from the My-bi HSC-enriched population. SCF + G-CSF enhanced the level of reconstitution of lymphoid-biased HSCs but not that of myeloid-biased HSCs. Clonal transplantation assay also showed that SCF + G-CSF did not increase the frequency of myeloid-biased HSCs. These data showed that G-CSF directly acted on lymphoid-biased HSCs but not myeloid-biased HSCs. Our study also revised the cytokine network at early stages of hematopoiesis: SCF directly acted on myeloid-biased HSCs; TPO directly acted on myeloid-biased HSCs and lymphoid-biased HSCs; and GM-CSF acted only on HPCs. Early hematopoiesis is controlled differentially and sequentially by a number of cytokines.

Generation and Evaluation of a Glaesserella (Haemophilus) parasuis Capsular Mutant.

Glaesserella (Haemophilus) parasuis is a commensal bacterium of the upper respiratory tract in pigs and also the causative agent of Glässer's disease, which causes significant morbidity and mortality in pigs worldwide. Isolates are characterized into 15 serovars by their capsular polysaccharide, which has shown a correlation with isolate pathogenicity. To investigate the role the capsule plays in G. parasuis virulence and host interaction, a capsule mutant of the serovar 5 strain HS069 was generated (HS069Δcap) through allelic exchange following natural transformation. HS069Δcap was unable to cause signs of systemic disease during a pig challenge study and had increased sensitivity to complement killing and phagocytosis by alveolar macrophages. Compared with the parent strain, HS069Δcap produced more robust biofilm and adhered equivalently to 3D4/31 cells; however, it was unable to persistently colonize the nasal cavity of inoculated pigs, with all pigs clearing HS069Δcap by 5 days postchallenge. Our results indicate the importance of the capsular polysaccharide to G. parasuis virulence as well as nasal colonization in pigs.

Parietal memory network and default mode network in first-episode drug-naïve schizophrenia: Associations with auditory hallucination.

Atypical spontaneous activities in resting-state networks may play a role in auditory hallucinations (AHs), but networks relevant to AHs are not apparent. Given the debating role of the default mode network (DMN) in AHs, a parietal memory network (PMN) may better echo cognitive theories of AHs in schizophrenia, because PMN is spatially adjacent to the DMN and more relevant to memory processing or information integration. To examine whether PMN is more relevant to AHs than DMN, we characterized these intrinsic networks in AHs with 59 first-episode, drug-naïve schizophrenics (26 AH+ and 33 AH-) and 60 healthy participants in resting-state fMRI. We separated the PMN, DMN, and auditory network (AN) using independent component analysis, and compared their functional connectivity across the three groups. We found that only AH+ patients displayed dysconnectivity in PMN, both AH+ and AH- patients exhibited dysfunctions of AN, but neither patient group showed abnormal connectivity within DMN. The connectivity of PMN significantly correlated with memory performance of the patients. Further region-of-interest analyses confirmed that the connectivity between the core regions of PMN, the left posterior cingulate gyrus and the left precuneus, was significantly lower only in the AH+ group. In exploratory correlation analysis, this functional connectivity metric significantly correlated with the severity of AH symptoms. The results implicate that compared to the DMN, the PMN is more relevant to the AH symptoms in schizophrenia, and further provides a more precise potential brain modulation target for the intervention of AH symptoms.

Annulation reaction enables the identification of an exocyclic amide tricyclic chemotype as retinoic acid Receptor-Related orphan receptor gamma (RORγ/RORc) inverse agonists.

RORγt is the master regulator of the IL-23/IL-17 axis, a pathway that is clinically validated for the treatment of various immunological disorders. Over the last few years, our group has reported different chemotypes that potently act as inverse agonists of RORγt. One of them, the tricyclic pyrrolidine chemotype, has demonstrated biologic-like preclinical efficacy and has led to our clinical candidate BMS-986251. In this letter, we discuss the invention of an annulation reaction which enabled the synthesis of a tricyclic exocyclic amide chemotype and the identification of compounds with RORγt inverse agonist activity. Preliminary structure activity relationships are disclosed.

Tricyclic sulfones as potent, selective and efficacious RORγt inverse agonists - Exploring C6 and C8 SAR using late-stage functionalization.

In order to rapidly develop C6 and C8 SAR of our reported tricyclic sulfone series of RORγt inverse agonists, a late-stage bromination was employed. Although not regioselective, the bromination protocol allowed us to explore new substitution patterns/vectors that otherwise would have to be incorporated at the very beginning of the synthesis. Based on the SAR obtained from this exercise, compound 15 bearing a C8 fluorine was developed as a very potent and selective RORγt inverse agonist. This analog's in vitro profile, pharmacokinetic (PK) data and efficacy in an IL-23 induced mouse acanthosis model will be discussed.

Evaluation of the recombinant proteins RlpB and VacJ as a vaccine for protection against Glaesserella parasuis in pigs.

BACKGROUND: Glaesserella parasuis, the causative agent of Glӓsser's disease, is widespread in swine globally resulting in significant economic losses to the swine industry. Prevention of Glӓsser's disease in pigs has been plagued with an inability to design broadly protective vaccines, as many bacterin based platforms generate serovar or strain specific immunity. Subunit vaccines are of interest to provide protective immunity to multiple strains of G. parasuis. Selected proteins for subunit vaccination should be widespread, highly conserved, and surface exposed. RESULTS: Two candidate proteins for subunit vaccination (RlpB and VacJ) against G. parasuis were identified using random mutagenesis and an in vitro organ culture system. Pigs were vaccinated with recombinant RlpB and VacJ, outer membrane proteins with important contributions to cellular function and viability. Though high antibody titers to the recombinant proteins and increased interferon-γ producing cells were found in subunit vaccinated animals, the pigs were not protected from developing systemic disease. CONCLUSIONS: It appears there may be insufficient RlpB and VacJ exposed on the bacterial surface for antibody to bind, preventing high RlpB and VacJ specific antibody titers from protecting animals from G. parasuis. Additionally, this work confirms the importance of utilizing the natural host species when assessing the efficacy of vaccine candidates.

Neurochemical and brain functional changes in the ventromedial prefrontal cortex of first-episode psychosis patients: A combined functional magnetic resonance imaging-proton magnetic resonance spectroscopy study.

OBJECTIVE: Previous studies showed alterations of brain function in the ventromedial prefrontal cortex of schizophrenia patients. Also, neurochemical changes, especially GABA level alteration, have been found in the medial prefrontal cortex of schizophrenia patients. However, the relationship between GABA level in the ventromedial prefrontal cortex and brain functional activity in schizophrenia patients remains unexplored. METHODS: In total, 23 drug-naïve, first-episode psychosis patients and 26 matched healthy controls completed the study. The single voxel proton magnetic resonance spectroscopy data were acquired in ventromedial prefrontal cortex region, which was used as the seed region for resting-state functional connectivity analysis. The proton magnetic resonance spectroscopy data were processed to quantify the concentrations of GABA+, glutamine and glutamate, and N-acetylaspartate in ventromedial prefrontal cortex. Spearman correlation analysis was used to examine the relationship between metabolite concentration, functional connectivity and clinical variables. Pearson correlation analysis was used to examine the relationship between GABA+ concentration and functional connectivity value. RESULTS: In first-episode psychosis patients, GABA+ level in ventromedial prefrontal cortex was higher and was positively correlated with ventromedial prefrontal cortex-left middle orbital frontal cortex functional connectivity. N-acetylaspartate level was positively correlated with positive symptoms, and the functional connectivity between ventromedial prefrontal cortex and left precuneus was negatively associated with negative symptoms of first-episode psychosis patients. CONCLUSION: Our results indicated that ventromedial prefrontal cortex functional connectivity changes were positively correlated with higher local GABA+ level in first-episode psychosis patients. The altered neurochemical concentration and functional connectivity provide insights into the pathology of schizophrenia.

Preoperative intra-aortic balloon pump inserted in acute myocardial infarction patients without cardiogenic shock undergoing surgical coronary revascularization.

OBJECTIVES: The benefit of preoperative intra-aortic balloon pump implantation in high-risk cardiac surgery patients is still debated. The role of preoperative intra-aortic balloon pump insertion in acute myocardial infarction patients without cardiogenic shock undergoing off-pump coronary artery bypass grafting remains unknown. This study aimed to determine the efficacy and safety of the preoperative intra-aortic balloon pump insertion in those patients undergoing off-pump coronary artery bypass grafting. METHODS: A total of 421 consecutive acute myocardial infarction patients without cardiogenic shock who underwent isolated off-pump coronary artery bypass grafting were enrolled in this retrospective observational propensity score-matched analysis study. Patients who received intra-aortic balloon pump before off-pump coronary artery bypass grafting (the intra-aortic balloon pump group, n = 157) were compared with those who had not (control group, n = 264). The 30-day postoperative survival, postoperative complications, and postoperative hospital length of stay were compared between the two groups. RESULTS: A total of 99 pairs of patients were matched. The preoperative intra-aortic balloon pump did not show a 30-day postoperative survival benefit compared with the control group (hazard ratio, 0.9; 95% confidence interval, 0.2-4.2; p = 0.92). Patients with preoperative intra-aortic balloon pump were more likely to have shorter postoperative lengths of stay (8 (6-11) days vs. 10 (6-15) days, p = 0.02) and decreased total days in the hospital (median days: 18.2 vs. 21.8, p = 0.02) compared to patients without balloon pumps. CONCLUSION: Preoperative intra-aortic balloon pump insertion in acute myocardial infarction patients without cardiogenic shock undergoing off-pump coronary artery bypass grafting improved convalescence as shown by significantly shorter postoperative lengths of hospital stay.

Exosomes derived from human umbilical cord mesenchymal stem cells alleviate acute liver failure by reducing the activity of the NLRP3 inflammasome in macrophages.

Human umbilical cord mesenchymal stem cell-derived exosomes (hUCMSC-EXOs) play an important role in the regulation of the immune system and inflammatory responses; however, their role in acute liver failure (ALF) and related pathological conditions is unclear. In this study, we found that hUCMSC-EXOs can reduce the expression of the NLRP3 inflammasome and downstream inflammatory factors in acute liver failure. Western blot and ELISA results showed that hUCMSC-EXOs decreased the expression of NLRP3, caspase-1, IL-1ß and IL-6 in LPS-stimulated RAW 264.7 macrophages. In vivo, the hUCMSC-EXOs repaired damaged liver tissue and decreased the expression of the NLRP3 inflammasome and the levels of ALT and AST in a mouse ALF model. The results of this study provide a new strategy for the application of human umbilical cord mesenchymal stem cell-derived exosomes in the treatment of ALF.

Pathotyping the Zoonotic Pathogen Streptococcus suis: Novel Genetic Markers To Differentiate Invasive Disease-Associated Isolates from Non-Disease-Associated Isolates from England and Wales.

Streptococcus suis is one of the most important zoonotic bacterial pathogens of pigs, causing significant economic losses to the global swine industry. S. suis is also a very successful colonizer of mucosal surfaces, and commensal strains can be found in almost all pig populations worldwide, making detection of the S. suis species in asymptomatic carrier herds of little practical value in predicting the likelihood of future clinical relevance. The value of future molecular tools for surveillance and preventative health management lies in the detection of strains that genetically have increased potential to cause disease in presently healthy animals. Here we describe the use of genome-wide association studies to identify genetic markers associated with the observed clinical phenotypes (i) invasive disease and (ii) asymptomatic carriage on the palatine tonsils of pigs on UK farms. Subsequently, we designed a multiplex PCR to target three genetic markers that differentiated 115 S. suis isolates into disease-associated and non-disease-associated groups, that performed with a sensitivity of 0.91, a specificity of 0.79, a negative predictive value of 0.91, and a positive predictive value of 0.79 in comparison to observed clinical phenotypes. We describe evaluation of our pathotyping tool, using an out-of-sample collection of 50 previously uncharacterized S. suis isolates, in comparison to existing methods used to characterize and subtype S. suis isolates. In doing so, we show our pathotyping approach to be a competitive method to characterize S. suis isolates recovered from pigs on UK farms and one that can easily be updated to incorporate global strain collections.

Mapping hepatic blood oxygenation by quantitative BOLD (qBOLD) MRI.

PURPOSE: Abnormalities in hepatic oxygen delivery and oxygen consumption may serve as a significant indicator of hepatic cellular dysfunction and may predict treatment response. However, conventional and oxygen-enhanced hepatic BOLD MRI can only provide semiquantitative assessment of hepatic oxygenation. METHODS: A hepatic quantitative BOLD (qBOLD) model was proposed for noninvasive mapping of hepatic venous blood oxygen saturation (Yv ) and deoxygenated blood volume (DBV) in human subjects. The validity and the estimation bias of the proposed model were evaluated by Monte Carlo simulations. Eight healthy subjects were scanned after written consent with institutional review board approval. RESULTS: Monte Carlo simulations demonstrated that the proposed single-compartment hepatic qBOLD model leads to significant deviation of the predicted T2* decay profile from the simulated signal due to high hepatic blood volume fraction. Small relative estimation bias for hepatic Yv and significant overestimation for hepatic DBV were observed, which can be corrected by applying the calibration curves established from simulations. After correction, the mean hepatic Yv in human subjects was 56.8 ± 6.8%, and the mean hepatic DBV was 0.190 ± 0.035, consistent with measurements from other invasive approaches. Except in regions with significant vascular contamination, the maps for hepatic Yv and DBV were relatively homogenous. CONCLUSIONS: With estimation bias correction, the hepatic qBOLD approach enables noninvasive mapping of hepatic blood volume and oxygenation in human subjects. The established protocol may be used to quantitatively assess hepatic tissue hypoxia in multiple liver diseases.

Rheb1 loss leads to increased hematopoietic stem cell proliferation and myeloid-biased differentiation in vivo.

Hematopoietic stem cells constitute a unique subpopulation of blood cells that can give rise to all types of mature cells in response to physiological demands. However, the intrinsic molecular machinery that regulates this transformative property remains elusive. In this paper, we demonstrate that small GTPase Rheb1 is a critical regulator of proliferation and differentiation of hematopoietic stem cells in vivo Rheb1 deletion led to increased phenotypic hematopoietic stem cell/hematopoietic progenitor cell proliferation under a steady state condition. Over-proliferating Rheb1-deficient hematopoietic stem cells were severely impaired in functional repopulation assays, and they failed to regenerate the blood system when challenged with hematopoietic ablation by sublethal irradiation. In addition, it was discovered that Rheb1 loss resulted in a lack of maturation of neutrophils / caused neutrophil immaturation by reducing mTORC1 activity, and that activation of the mTORC1 signaling pathway by mTOR activator 3BDO partially restored the maturation of Rheb1-deficient neutrophils. Rheb1 deficiency led to a progressive enlargement of the hematopoietic stem cell population and an eventual excessive myeloproliferation in vivo, including an overproduction of peripheral neutrophils and an excessive expansion of extramedullary hematopoiesis. Moreover, low RHEB expression was correlated with poor survival in acute myeloid leukemia patients with normal karyotype. Our results, therefore, demonstrate a critical and unique role for Rheb1 in maintaining proper hematopoiesis and myeloid differentiation.