Organoid models of human and mouse ductal pancreatic cancer.

Pancreatic cancer is one of the most lethal malignancies due to its late diagnosis and limited response to treatment. Tractable methods to identify and interrogate pathways involved in pancreatic tumorigenesis are urgently needed. We established organoid models from normal and neoplastic murine and human pancreas tissues. Pancreatic organoids can be rapidly generated from resected tumors and biopsies, survive cryopreservation, and exhibit ductal- and disease-stage-specific characteristics. Orthotopically transplanted neoplastic organoids recapitulate the full spectrum of tumor development by forming early-grade neoplasms that progress to locally invasive and metastatic carcinomas. Due to their ability to be genetically manipulated, organoids are a platform to probe genetic cooperation. Comprehensive transcriptional and proteomic analyses of murine pancreatic organoids revealed genes and pathways altered during disease progression. The confirmation of many of these protein changes in human tissues demonstrates that organoids are a facile model system to discover characteristics of this deadly malignancy.

Diabetes risk gene and Wnt effector Tcf7l2/TCF4 controls hepatic response to perinatal and adult metabolic demand.

Most studies on TCF7L2 SNP variants in the pathogenesis of type 2 diabetes (T2D) focus on a role of the encoded transcription factor TCF4 in ß cells. Here, a mouse genetics approach shows that removal of TCF4 from ß cells does not affect their function, whereas manipulating TCF4 levels in the liver has major effects on metabolism. In Tcf7l2(-/-) mice, the immediate postnatal surge in liver metabolism does not occur. Consequently, pups die due to hypoglycemia. By combining chromatin immunoprecipitation with gene expression profiling, we identify a TCF4-controlled metabolic gene program that is acutely activated in the postnatal liver. In concordance, adult liver-specific Tcf7l2 knockout mice show reduced hepatic glucose production during fasting and display improved glucose homeostasis when maintained on high-fat diet. Furthermore, liver-specific TCF4 overexpression increases hepatic glucose production. These observations imply that TCF4 directly activates metabolic genes and that inhibition of Wnt signaling may be beneficial in metabolic disease.

RNF43 truncations trap CK1 to drive niche-independent self-renewal in cancer.

Wnt/ß-catenin signaling is a primary pathway for stem cell maintenance during tissue renewal and a frequent target for mutations in cancer. Impaired Wnt receptor endocytosis due to loss of the ubiquitin ligase RNF43 gives rise to Wnt-hypersensitive tumors that are susceptible to anti-Wnt-based therapy. Contrary to this paradigm, we identify a class of RNF43 truncating cancer mutations that induce ß-catenin-mediated transcription, despite exhibiting retained Wnt receptor downregulation. These mutations interfere with a ubiquitin-independent suppressor role of the RNF43 cytosolic tail that involves Casein kinase 1 (CK1) binding and phosphorylation. Mechanistically, truncated RNF43 variants trap CK1 at the plasma membrane, thereby preventing ß-catenin turnover and propelling ligand-independent target gene transcription. Gene editing of human colon stem cells shows that RNF43 truncations cooperate with p53 loss to drive a niche-independent program for self-renewal and proliferation. Moreover, these RNF43 variants confer decreased sensitivity to anti-Wnt-based therapy. Our data demonstrate the relevance of studying patient-derived mutations for understanding disease mechanisms and improved applications of precision medicine.

Spatiotemporal dynamics of animal contests arise from effective forces between contestants.

Competition among animals for resources, notably food, territories, and mates, is ubiquitous at all scales of life. This competition is often resolved through contests among individuals, which are commonly understood according to their outcomes and in particular, how these outcomes depend on decision-making by the contestants. Because they are restricted to end-point predictions, these approaches cannot predict real-time or real-space dynamics of animal contest behavior. This limitation can be overcome by studying systems that feature typical contest behavior while being simple enough to track and model. Here, we propose to use such systems to construct a theoretical framework that describes real-time movements and behaviors of animal contestants. We study the spatiotemporal dynamics of contests in an orb-weaving spider, in which all the common elements of animal contests play out. The confined arena of the web, on which interactions are dominated by vibratory cues in a two-dimensional space, simplifies the analysis of interagent interactions. We ask whether these seemingly complex decision-makers can be modeled as interacting active particles responding only to effective forces of attraction and repulsion due to their interactions. By analyzing the emergent dynamics of "contestant particles," we provide mechanistic explanations for real-time dynamical aspects of animal contests, thereby explaining competitive advantages of larger competitors and demonstrating that complex decision-making need not be invoked in animal contests to achieve adaptive outcomes. Our results demonstrate that physics-based classification and modeling, in terms of effective rules of interaction, provide a powerful framework for understanding animal contest behaviors.

Long-term expanding human airway organoids for disease modeling.

Organoids are self-organizing 3D structures grown from stem cells that recapitulate essential aspects of organ structure and function. Here, we describe a method to establish long-term-expanding human airway organoids from broncho-alveolar resections or lavage material. The pseudostratified airway organoids consist of basal cells, functional multi-ciliated cells, mucus-producing secretory cells, and CC10-secreting club cells. Airway organoids derived from cystic fibrosis (CF) patients allow assessment of CFTR function in an organoid swelling assay. Organoids established from lung cancer resections and metastasis biopsies retain tumor histopathology as well as cancer gene mutations and are amenable to drug screening. Respiratory syncytial virus (RSV) infection recapitulates central disease features, dramatically increases organoid cell motility via the non-structural viral NS2 protein, and preferentially recruits neutrophils upon co-culturing. We conclude that human airway organoids represent versatile models for the in vitro study of hereditary, malignant, and infectious pulmonary disease.

Behavioral traits that define social dominance are the same that reduce social influence in a consensus task.

Dominant individuals are often most influential in their social groups, affecting movement, opinion, and performance across species and contexts. Yet, behavioral traits like aggression, intimidation, and coercion, which are associated with and in many cases define dominance, can be socially aversive. The traits that make dominant individuals influential in one context may therefore reduce their influence in other contexts. Here, we examine this association between dominance and influence using the cichlid fish Astatotilapia burtoni, comparing the influence of dominant and subordinate males during normal social interactions and in a more complex group consensus association task. We find that phenotypically dominant males are aggressive, socially central, and that these males have a strong influence over normal group movement, whereas subordinate males are passive, socially peripheral, and have little influence over normal movement. However, subordinate males have the greatest influence in generating group consensus during the association task. Dominant males are spatially distant and have lower signal-to-noise ratios of informative behavior in the association task, potentially interfering with their ability to generate group consensus. In contrast, subordinate males are physically close to other group members, have a high signal-to-noise ratio of informative behavior, and equivalent visual connectedness to their group as dominant males. The behavioral traits that define effective social influence are thus highly context specific and can be dissociated with social dominance. Thus, processes of hierarchical ascension in which the most aggressive, competitive, or coercive individuals rise to positions of dominance may be counterproductive in contexts where group performance is prioritized.

Integral inequalities for closed linear Weingarten submanifolds in the product spaces.

An integral inequality for closed linear Weingarten 𝑚-submanifolds with parallel normalized mean curvature vector field (pnmc lw-submanifolds) in the product spaces 𝑀𝑛(𝑐) × â„, 𝑛 > 𝑚 ≥ 4, where 𝑀𝑛(𝑐) is a space form of constant sectional curvature 𝑐 ∈ {-1, 1}, is proved. As an application is shown that the sharpness in this inequality is attained in the totally umbilical hypersurfaces, and in a certain family of standard product of the form 𝕊1(√1 - 𝑟2) × ð•Šð‘š-1(𝑟) with 0 < 𝑟 < 1 when 𝑐 = 1. In the case where 𝑐 = -1, is obtained an integral inequality whose sharpness is attained only in the totally umbilical hypersurfaces. When 𝑚 = 2 and 𝑚 = 3, an integral inequality is also obtained with equality happening in the totally umbilical hypersurfaces.

Burden of HIV-related stigma and associated factors among women living with depression accessing PMTCT services in Dar es Salaam, Tanzania.

HIV-related stigma represents a potent risk factor for a range of poor health outcomes, including mental health symptoms, treatment non-adherence, and substance use. Understanding the role of HIV-related stigma in promoting healthcare outcomes is critical for vulnerable populations, such as pregnant women living with HIV, in contexts with continued high rates of HIV and associated stigma, such as sub-Saharan Africa. The current study examined a range of risk and protective factors for HIV-related stigma with 742 pregnant women (M age = 29.6 years) living with depression and HIV accessing prevention of mother-to-child transmission of HIV (PMTCT) services in Dar es Salaam, Tanzania. Risk factors included depressive symptoms, ART non-adherence, intimate partner violence, food insecurity, and alcohol problems. Protective factors included disclosure of HIV status, social support, an appreciative relationship with their partner, hope, and self-efficacy. Findings highlight key psychosocial and behavioral determinants of HIV-related stigma for pregnant women living with HIV in Tanzania, and can inform perinatal care programming and interventions to optimize mental health and adherence outcomes.

Diabetic ketoacidosis: a canary in the mine for mental health disorders?

BACKGROUND: Recurrent diabetic ketoacidosis (DKA) has been linked to mental health disorders, but less is known about single DKA episodes. Most studies are retrospective, lacking control groups. AIMS: To prospectively examine psychosocial factors in patients presenting with recurrent or single episode DKA and compare with people who have not had DKA. METHODS: Case-controlled study (consecutive adult DKA admissions April 2015 to December 2016) at Western Health, Melbourne. Data were prospectively collected regarding diagnosed mental health disorders, likely depression (Patient Health Questionnaire (PHQ-9)), diabetes distress (Problem Areas in Diabetes (PAID) questionnaire) and presence of adverse social factors. A control group without a history of DKA was also recruited. RESULTS: Of 123 patients admitted with DKA (164 consecutive episodes), 70 consented to participate and 73 age-matched Type 1 diabetes controls were recruited. Eleven (61%) of 18 with recurrent DKA had a diagnosed mental health disorder versus 8 (19%) of 42 in the single episode group (P = 0.016). The prevalence of likely depression using PHQ-9 was: recurrent 50%; single 40%; and controls 22% (recurrent vs controls, P = 0.036; single vs controls, P = 0.053). Severe diabetes distress (PAID) was present in 47% of recurrent and 34% of single episode DKA (P = 0.387). As a group, DKA patients had significantly more unemployment, illicit drug use and tobacco smoking, a lower level of formal education and less regular medical contact compared with controls. CONCLUSIONS: Mental health disorders and adverse socioeconomic factors appear to be common in patients with DKA. The diagnosis of DKA presents an excellent opportunity to screen for depression and offer appropriate intervention.

Optimal Oxygen Targets in Term Lambs with Meconium Aspiration Syndrome and Pulmonary Hypertension.

Optimal oxygen saturation as measured by pulse oximetry (SpO2) in neonatal lung injury, such as meconium aspiration syndrome (MAS) and persistent pulmonary hypertension of newborn (PPHN), is not known. Our goal was to determine the SpO2 range in lambs with MAS and PPHN that results in the highest brain oxygen delivery (bDO2) and pulmonary blood flow (Qp) and the lowest pulmonary vascular resistance and oxidative stress. Meconium was instilled into endotracheal tubes in 25 near-term gestation lambs, and the umbilical cord was occluded to induce asphyxia and gasping, causing MAS and PPHN. Lambs were randomized into four groups and ventilated for 6 hours with fixed fraction of inspired oxygen (FiO2) = 1.0 irrespective of SpO2, and three groups had FiO2 titrated to keep preductal SpO2 between 85% and 89%, 90% and 94%, and 95% and 99%, respectively. Tissues were collected to measure nitric oxide synthase activity, 3-nitrotyrosine, and 8-isoprostanes. Throughout the 6-hour exposure period, lambs in the 95-99% SpO2 target group had the highest Qp, lowest pulmonary vascular resistance, and highest bDO2 but were exposed to higher FiO2 (0.5 ± 0.21 vs. 0.29 ± 0.17) with higher lung 3-nitrotyrosine (0.67 [interquartile range (IQR), 0.43-0.73] ng/mcg protein vs. 0.1 [IQR, 0.09-0.2] ng/mcg protein) and lower lung nitric oxide synthase activity (196 [IQR, 192-201] mMol nitrite/mg protein vs. 270 [IQR, 227-280] mMol nitrite/mg protein) compared with the 90-94% target group. Brain 3-nitrotyrosine was lower in the 85-89% target group, and brain/lung 8-isoprostane levels were not significantly different. In term lambs with MAS and PPHN, Qp and bDO2 through the first 6 hours are higher with target SpO2 in the 95-99% range. However, the 90-94% target range is associated with significantly lower FiO2 and lung oxidative stress. Clinical trials comparing the 90-94% versus the 95-99% SpO2 target range in term infants with PPHN are warranted.

Factors associated with depressive symptoms and suicidal ideation and behaviours amongst sub-Saharan African adolescents aged 10-19 years: cross-sectional study.

OBJECTIVE: This study aimed to determine the burden of depression, suicidal ideation and suicidal behaviour amongst adolescents at sites in six sub-Saharan African countries and examine associated risk and protective factors. METHODS: Household-based cross-sectional study involving male and female adolescents ages 10-19 years. A total of 7,662 adolescents from eight sites in six countries participated in the survey. Three sites were urban: Dar es Salaam (Tanzania), Harar (Ethiopia) and Ibadan (Nigeria); five were rural: Dodoma (Tanzania), Iganga/Mayuge (Uganda), Kersa (Ethiopia), Ningo Prampram (Ghana) and Nouna (Burkina Faso). Log-binomials models were used to estimate relative risks and confidence intervals for factors associated with depression and suicidal behaviour. This was supplemented using log-Poisson models as needed. RESULTS: The prevalence of suicidal behaviour over the last 12 months ranged between 1.2% and 12.4% in the eight sites. Depressive symptoms and suicidal ideation/behaviours were associated with older age, female sex, food insecurity, poor access to health care and substance use. Depression was strongly associated with increased risk of suicidal behaviour at two sites where the multivariate model converged: Harar, Ethiopia (RR = 3.5, 95% CI 1.8, 7.0, P < 0.05) and Ibadan, Nigeria (RR = 3.7, 95% CI 2.2, 6.3, P < 0.0001). CONCLUSIONS: Depressive symptoms and suicidal behaviour are common amongst sub-Saharan African adolescents at these 8 sites. Most factors associated with depressive symptoms are modifiable and preventable. Routine screening for depressive symptoms in services frequented by adolescents in these and similar communities would be crucial in early detection and prompt intervention.

OBJECTIF: Cette étude visait à déterminer la charge de morbidité de la dépression, des idées suicidaires et du comportement suicidaire chez les adolescents sur des sites dans six pays d'Afrique subsaharienne et examiner les facteurs de risque et de protection associés. MÉTHODES: Etude transversale réalisée auprès des ménages sur des adolescents masculins et féminins âgés de 10 à 19 ans. 7.662 adolescents de huit sites dans six pays ont participé à l'enquête. Trois sites étaient en zones urbaines: Dar es Salaam (Tanzanie), Harar (Ethiopie) et Ibadan (Nigéria); cinq étaient en zones rurales: Dodoma (Tanzanie), Iganga/Mayuge (Ouganda), Kersa (Ethiopie), Ningo Prampram (Ghana) et Nouna (Burkina Faso). Des modèles de logarithme binomial ont été utilisés pour estimer les risques relatifs et les intervalles de confiance pour les facteurs associés à la dépression et au comportement suicidaire. Cela a été complété à l'aide de modèles log-Poisson lorsque nécessaire. RÉSULTATS: La prévalence des comportements suicidaires au cours des 12 derniers mois variait entre 1,2% et 12,4% dans les huit sites. Les symptômes dépressifs et les idées/comportements suicidaires étaient associés à l'âge plus avancé, au sexe féminin, à l'insécurité alimentaire, au faible accès aux soins de santé et à la toxicomanie. La dépression était fortement associée à un risque accru de comportement suicidaire sur deux sites où il y avait une convergence dans le modèle multivarié: Harar, en Ethiopie (RR = 3,5; IC95%: 1,8-7,0; P < 0,05) et Ibadan, au Nigéria (RR = 3,7; IC95%: 2,2-6,3; P < 0,0001). CONCLUSIONS: Les symptômes dépressifs et les comportements suicidaires sont fréquents chez les adolescents africains subsahariens de ces 8 sites. La plupart des facteurs associés aux symptômes dépressifs sont modifiables et évitables. Le dépistage de routine des symptômes dépressifs dans les services fréquentés par les adolescents dans ces communautés et dans des communautés similaires serait crucial pour la détection précoce et une intervention rapide.

Correction: The Leukemia-Associated Mllt10/Af10-Dot1l Are Tcf4/ß-Catenin Coactivators Essential for Intestinal Homeostasis.

[This corrects the article DOI: 10.1371/journal.pbio.1000539.].

Healthy Options: study protocol and baseline characteristics for a cluster randomized controlled trial of group psychotherapy for perinatal women living with HIV and depression in Tanzania.

BACKGROUND: Perinatal women accessing prevention of mother-to-child transmission of HIV (PMTCT) services are at an increased risk of depression; however, in Tanzania there is limited access to services provided by mental health professionals. This paper presents a protocol and baseline characteristics for a study evaluating a psychosocial support group intervention facilitated by lay community-based health workers (CBHWs) for perinatal women living with HIV and depression in Dar es Salaam. METHODS: A cluster randomized controlled trial (RCT) is conducted comparing: 1) a psychosocial support group intervention; and 2) improved standard of mental health care. The study is implemented in reproductive and child health (RCH) centers providing PMTCT services. Baseline characteristics are presented by comparing sociodemographic characteristics and primary as well as secondary outcomes for the trial for intervention and control groups. The trial is registered under clinicaltrials.gov (NCT02039973). RESULTS: Among 742 women enrolled, baseline characteristics were comparable for intervention and control groups, although more women in the control group had completed secondary school (25.2% versus 18.2%). Overall, findings suggest that the population is highly vulnerable with over 45% demonstrating food insecurity and 17% reporting intimate partner violence in the past 6 months. CONCLUSIONS: Baseline characteristics for the cluster RCT were comparable for intervention and control groups. The trial will examine the effectiveness of a psychosocial support group intervention for the treatment of depression among women living with HIV accessing PMTCT services. A reduction in the burden of depression in this vulnerable population has implications in the short-term for improved HIV-related outcomes and for potential long-term effects on child growth and development. TRIAL REGISTRATION: The trial is registered under clinicaltrials.gov (NCT02039973). Retrospectively registered on January 20, 2014.

Prevalence of rotavirus and human bocavirus in immunosuppressed individuals after renal transplantation in the Northern Region of Brazil.

Immunosuppressive therapy causes severe impairment of host defense and diarrhea is a frequent complication in renal transplant recipients. This study aimed to describe the occurrence of Rotavirus A (RVA) and Human Bocavirus (HBoV) in fecal samples of immunosuppressed patients submitted to renal transplantation during posttransplant follow-up. A longitudinal study was carried out involving a 25-patient cohort, selected for kidney transplantation. A total of 126 fecal samples were collected between May 2014 and May 2016. Molecular techniques were used to detect and characterize circulating RVA and HBoV genotypes and statistical analysis were applied to verify the association between epidemiological and clinical characteristics. The prevalence of RVA and HBoV was 24% (6/25) and 40% (10/25), respectively. Among RVA and HBoV positive cases, the majority was female; did not conduct water treatment nor had adequate sewage facilities. The most detected genotypes were RVA G3 (62.5%) and HBoV-3 (95%). Phylogenetic analysis of HBoV strains indicated that studied samples were similar to those found in Asian and American countries. The present study point out the circulation of these viral agents among immunosuppressed individuals and these findings will enable the construction of new knowledge and care perspectives on the cause of diarrhea in this population.

Emergence of G12P[6] rotavirus strains among hospitalised children with acute gastroenteritis in Belém, Northern Brazil, following introduction of a rotavirus vaccine.

Species A rotavirus still remains a major cause of acute gastroenteritis in infants and young children. Globally, six genotypes (G1P[8], G2P[4], G3P[8], G4P[8], G9P[8] and G12P[8]) account for >90% of circulating strains; however, genotype G12 in combination with P[6] or P[9] has been detected at increasing rates. We sought to broaden our knowledge about the rotavirus strains circulating during the early post-vaccine-introduction period. Stool samples were obtained from children hospitalised for acute gastroenteritis in Belém, Northern Brazil, from May 2008 to May 2011 and examined by reverse transcription polymerase chain reaction and nucleotide sequencing. A total of 122 out of the original 1076 rotavirus strains were judged to be non-typeable in the first analysis and were therefore re-examined. G2P[4] was the most prevalent genotype (58.0%), followed by G1P[8] (16.9%), and G12P[6] (7.5%). G12P[6] strains were identified at similar rates during the first (2.5%) and second (3.9%) years, and the rate jumped to 15.6% in the third year. Analysis of VP7 sequences of the G12P[6] strains showed that they belonged to lineage III. In addition, co-circulating G12P[6] strains displaying long and short RNA patterns were found to belong to the Wa-like and DS-1-like constellation, respectively. Additional unusual circulating strains G12P[9] and G3P[9] were also identified. This hospital-based study showed a high prevalence of G12P[6] strains in the third year of surveillance. Our results highlight the need for continuous longitudinal monitoring of circulating rotavirus strains after introduction of rotavirus vaccines in Brazil and elsewhere.

In vitro expansion of single Lgr5+ liver stem cells induced by Wnt-driven regeneration.

The Wnt target gene Lgr5 (leucine-rich-repeat-containing G-protein-coupled receptor 5) marks actively dividing stem cells in Wnt-driven, self-renewing tissues such as small intestine and colon, stomach and hair follicles. A three-dimensional culture system allows long-term clonal expansion of single Lgr5(+) stem cells into transplantable organoids (budding cysts) that retain many characteristics of the original epithelial architecture. A crucial component of the culture medium is the Wnt agonist RSPO1, the recently discovered ligand of LGR5. Here we show that Lgr5-lacZ is not expressed in healthy adult liver, however, small Lgr5-LacZ(+) cells appear near bile ducts upon damage, coinciding with robust activation of Wnt signalling. As shown by mouse lineage tracing using a new Lgr5-IRES-creERT2 knock-in allele, damage-induced Lgr5(+) cells generate hepatocytes and bile ducts in vivo. Single Lgr5(+) cells from damaged mouse liver can be clonally expanded as organoids in Rspo1-based culture medium over several months. Such clonal organoids can be induced to differentiate in vitro and to generate functional hepatocytes upon transplantation into Fah(-/-) mice. These findings indicate that previous observations concerning Lgr5(+) stem cells in actively self-renewing tissues can also be extended to damage-induced stem cells in a tissue with a low rate of spontaneous proliferation.

Validating the Patient Health Questionnaire-9 (PHQ-9) for screening of depression in Tanzania.

BACKGROUND: Major depression has a significant impact on years lived with disability (YLD) globally. In resource-limited countries, depression may accompany daily challenges of economic security that people face, hence there is a critical need to develop depression screening tools at primary levels of health care. The overall goal of the study is to validate the PHQ-9 in Tanzania. METHODS: A validation study was conducted from August to October 2014 among adults accessing primary health care at public clinics in Dar es Salaam. The Mini-International Neuropsychiatric Interview (MINI) was used as the gold standard for current major depressive episode. RESULTS: Among 180 patients recruited, six were not included in the analysis since the PHQ-9 and MINI assessments were conducted more than two weeks apart (n=174). The PHQ-9 demonstrated reasonable reliability in this setting (α=0.83). Evidence for construct validity was observed through expected associations with female gender (r=0.16, p=0.04) and food insecurity (r=0.30, p<0.0001). Receiver Operating Characteristic analysis demonstrated good overall accuracy of the PHQ-9 (AOC=0.87, 95%CI: 0.77, 0.96). The optimal cut-off score in this population was 9, with a sensitivity of 78% and specificity of 87%. LIMITATIONS: The study sample is from a primary health care setting, hence the findings may have some limited generalizability at the community level. CONCLUSIONS: The PHQ-9 demonstrated reliability and validity among adults accessing primary health care in Dar es Salaam, indicating that it can serve as a useful tool in identifying patients with depression in primary care clinics in Tanzania and similar settings.

Effect of various inspired oxygen concentrations on pulmonary and systemic hemodynamics and oxygenation during resuscitation in a transitioning preterm model.

BACKGROUND: The Neonatal Resuscitation Program recommends initial resuscitation of preterm infants with low oxygen (O2) followed by titration to target preductal saturations (SpO2). We studied the effect of resuscitation with titrated O2 on gas exchange, pulmonary, and systemic hemodynamics. METHODOLOGY: Twenty-nine preterm lambs (127 d gestation) were randomized to resuscitation with 21% O2 (n = 7), 100% O2 (n = 6), or initiation at 21% and titrated to target SpO2 (n = 16). Seven healthy term control lambs were ventilated with 21% O2. RESULTS: Preductal SpO2 achieved by titrating O2 was within the desired range similar to term lambs in 21% O2. Resuscitation of preterm lambs with 21% and 100% O2 resulted in SpO2 below and above the target, respectively. Ventilation of preterm lambs with 100% O2 and term lambs with 21% O2 effectively decreased pulmonary vascular resistance (PVR). In contrast, preterm lambs with 21% O2 and titrated O2 demonstrated significantly higher PVR than term lambs on 21% O2. CONCLUSION(S): Initial resuscitation with 21% O2 followed by titration of O2 led to suboptimal pulmonary vascular transition at birth in preterm lambs. Ventilation with 100% O2 in preterm lambs caused hyperoxia but reduced PVR similar to term lambs on 21% O2. Studies evaluating the initiation of resuscitation at a higher O2 concentration followed by titration based on SpO2 in preterm neonates are needed.

Proteolytic cleavage of ataxin-7 promotes SCA7 retinal degeneration and neurological dysfunction.

The neurodegenerative disorder spinocerebellar ataxia type 7 (SCA7) is caused by a polyglutamine (polyQ) expansion in the ataxin-7 protein, categorizing SCA7 as one member of a large class of heritable neurodegenerative proteinopathies. Cleavage of ataxin-7 by the protease caspase-7 has been demonstrated in vitro, and the accumulation of proteolytic cleavage products in SCA7 patients and mouse models has been identified as an early pathological change. However, it remains unknown whether a causal relationship exists between ataxin-7 proteolysis and in vivo SCA7 disease progression. To determine whether caspase cleavage is a critical event in SCA7 disease pathogenesis, we generated transgenic mice expressing polyQ-expanded ataxin-7 with a second-site mutation (D266N) to prevent caspase-7 proteolysis. When we compared SCA7-D266N mice with SCA7 mice lacking the D266N mutation, we found that SCA7-D266N mice exhibited improved motor performance, reduced neurodegeneration and substantial lifespan extension. Our findings indicate that proteolysis at the D266 caspase-7 cleavage site is an important mediator of ataxin-7 neurotoxicity, suggesting that inhibition of caspase-7 cleavage of polyQ-ataxin-7 may be a promising therapeutic strategy for this untreatable disorder.

Unlimited in vitro expansion of adult bi-potent pancreas progenitors through the Lgr5/R-spondin axis.

Lgr5 marks adult stem cells in multiple adult organs and is a receptor for the Wnt-agonistic R-spondins (RSPOs). Intestinal, stomach and liver Lgr5(+) stem cells grow in 3D cultures to form ever-expanding organoids, which resemble the tissues of origin. Wnt signalling is inactive and Lgr5 is not expressed under physiological conditions in the adult pancreas. However, we now report that the Wnt pathway is robustly activated upon injury by partial duct ligation (PDL), concomitant with the appearance of Lgr5 expression in regenerating pancreatic ducts. In vitro, duct fragments from mouse pancreas initiate Lgr5 expression in RSPO1-based cultures, and develop into budding cyst-like structures (organoids) that expand five-fold weekly for >40 weeks. Single isolated duct cells can also be cultured into pancreatic organoids, containing Lgr5 stem/progenitor cells that can be clonally expanded. Clonal pancreas organoids can be induced to differentiate into duct as well as endocrine cells upon transplantation, thus proving their bi-potentiality.