Po-Nien Tsao

Notch signaling controls the balance of ciliated and secretory cell fates in developing airways

Although there is accumulated evidence of a role for Notch in the developing lung, it is still unclear how disruption of Notch signaling affects lung progenitor cell fate and differentiation events in the airway epithelium. To address this issue, we inactivated Notch signaling conditionally in the endoderm using a Shh-Cre deleter mouse line and mice carrying floxed alleles of the Pofut1 gene, which encodes an O-fucosyltransferase essential for Notch-ligand binding. We also took the same conditional approach to inactivate expression of Rbpjk, which encodes the transcriptional effector of canonical Notch signaling. Strikingly, these mutants showed an almost identical lung phenotype characterized by an absence of secretory Clara cells without evidence of cell death, and showed airways populated essentially by ciliated cells, with an increase in neuroendocrine cells. This phenotype could be further replicated in cultured wild-type lungs by disrupting Notch signaling with a gamma-secretase inhibitor. Our data suggest that Notch acts when commitment to a ciliated or non-ciliated cell fate occurs in proximal progenitors, silencing the ciliated program in the cells that will continue to expand and differentiate into secretory cells. This mechanism may be crucial to define the balance of differentiated cell profiles in different generations of the developing airways. It might also be relevant to mediate the metaplastic changes in the respiratory epithelium that occur in pathological conditions, such as asthma and chronic obstructive pulmonary disease.

Handwashing Program for the Prevention of Nosocomial Infections in a Neonatal Intensive Care Unit

OBJECTIVE To evaluate the effects of a hand hygiene program on compliance with hand hygiene and the rate of nosocomial infections in a neonatal intensive care unit (NICU). DESIGN Open trial. SETTING A level-III NICU in a teaching hospital. PARTICIPANTS Nurses, physicians, and other healthcare workers in the NICU. INTERVENTIONS A multimodal campaign for hand hygiene promotion was conducted beginning in September 1998. This program consisted of formal lectures, written instructions and posted reminders regarding hand hygiene and proper handwashing techniques, covert observation, financial incentives, and regular group feedback on compliance. Surveillance of handwashing compliance and nosocomial infections before and during the program was analyzed. RESULTS Overall compliance with hand hygiene improved from 43% at baseline to 80% during the promotion program. The rate of nosocomial infections decreased from 15.13 to 10.69 per 1,000 patient-days (P = .003) with improved handwashing compliance. In particular, respiratory tract infections decreased from 3.35 to 1.06 per 1,000 patient-days during the handwashing campaign (P = .002). Furthermore, the correlation between nosocomial infection of the respiratory tract and handwashing compliance also reached statistical significance (r = -0.385; P = .014). CONCLUSIONS Improved compliance with handwashing was associated with a significant decrease in overall rates of nosocomial infection and respiratory infections in particular. Washing hands is a simple, economical, and effective method for preventing nosocomial infections in the NICU.

Placenta growth factor expression is correlated with survival of patients with colorectal cancer

Background: Overexpression of vascular endothelial growth factor (VEGF) correlates with vascularity, metastasis, and proliferation in colorectal cancer but the role of its homologue, placenta growth factor (PlGF), is unknown. The aim of this study was to evaluate expression and clinical implications of PlGF in colorectal cancer. Methods: We investigated 74 tumour/non-tumour pairs of colorectal cryosections. Clinical staging was based on the UICC-TNM classification. Expression levels of mRNA for PlGF and VEGF were analysed with quantitative real time reverse transcription-polymerase chain reaction. Proteins were analysed by immunohistochemical staining and enzyme linked immunoabsorbant assay. Analysis of the differences in PlGF and VEGF levels between tumour and non-tumour tissues in the same patient were performed by paired t test; differences between localised and advanced disease patients by the Mann-Whitney, χ2, and Fisher’s exact tests and survival curves by the Kaplan-Meier method. Results: Expression levels for both growth factors were significantly higher in tumour than in non-tumour tissues (p⩽0.001). The ratio of PlGF expression in tumour to non-tumour in the advanced disease group was significantly higher than for the localised disease group (p = 0.009). Patients with more tumour PlGF mRNA had shorter survival (p = 0.028). The majority of PlGF was expressed in tumour cells. Conclusions: Our results suggest that PlGF expression correlates with disease progression and patient survival and may be used as a prognostic indicator for colorectal cancer.

γ-Secretase Activation of Notch Signaling Regulates the Balance of Proximal and Distal Fates in Progenitor Cells of the Developing Lung

Little is known about the mechanisms by which the lung epithelial progenitors are initially patterned and how proximal-distal boundaries are established and maintained when the lung primordium forms and starts to branch. Here we identified a number of Notch pathway components in respiratory progenitors of the early lung, and we investigated the role of Notch in lung pattern formation. By preventing γ-secretase cleavage of Notch receptors, we have disrupted global Notch signaling in the foregut and in the lung during the initial stages of murine lung morphogenesis. We demonstrate that Notch signaling is not necessary for lung bud initiation; however, Notch is required to maintain a balance of proximal-distal cell fates at these early stages. Disruption of Notch signaling dramatically expands the population of distal progenitors, altering morphogenetic boundaries and preventing formation of proximal structures. Our data suggest a novel mechanism in which Notch and fibroblast growth factor signaling interact to control the proximal-distal pattern of forming airways in the mammalian lung.

Parental Smoking During Pregnancy and Its Association with Low Birth Weight, Small for Gestational Age, and Preterm Birth Offspring: A Birth Cohort Study

BACKGROUND Intrauterine exposure to tobacco smoke has been discerned as an important risk factor for low birth weight (LBW), small for gestational age (SGA), and preterm birth infants. In this cohort study, we investigated the association of the amount of parental smoking during the different pregnancy stages with birth weight and the incidence of preterm delivery. METHODS Our study population was acquired from the Taiwan Birth Cohort Study. Between June 2005 and July 2006, 21,248 postpartum women were interviewed 6 months after their deliveries by a structured questionnaire. The parents were divided into four groups according to the amount of smoking during preconception, the first trimester, and the second and third trimesters. The relationships of parental smoking with gestational age and birth weight during the different pregnancy stages were assessed using multivariate linear regression. Multiple logistic regression analyses were performed to estimate the odds ratios and 95% confidence intervals of preterm delivery, LBW, and SGA infants during the different parental smoking status and the different pregnancy stages. RESULTS After adjusting for the physical and socioeconomic status of the parents and for paternal smoking during the same period, we found that maternal smoking decreased birth weight. Compared with the nonsmoking groups, all the maternal smoking groups had higher incidences of LBW, SGA, and preterm birth infants, especially when the mothers smoked >20 cigarettes/day. The association of paternal smoking with LBW, SGA, and preterm birth infants was insignificant. CONCLUSION Maternal smoking is responsible for increased incidences of LBW and preterm delivery of babies, and therefore, smoking cessation/reduction should be advised to pregnant women to reduce morbidities in their neonates. Further studies are needed to clarify the correlation of fetal health with passive smoking, including exposure to environmental tobacco smoke and to other smokers in the family.

Notch signaling prevents mucous metaplasia in mouse conducting airways during postnatal development

Goblet cell metaplasia and mucus overproduction contribute to the pathogenesis of chronic lung diseases, including asthma and chronic obstructive pulmonary disease (COPD). Notch signaling regulates cell fate decisions and is crucial in controlling goblet cell differentiation in the gut epithelium. Little is known, however, about how endogenous Notch signaling influences the goblet cell differentiation program that takes place in the postnatal lung. Using a combination of genetic and in vitro approaches here we provide evidence of a novel role for Notch in restricting goblet cell differentiation in the airway epithelium during the postnatal period. Conditional inactivation of the essential Notch pathway component Pofut1 (protein O-fucosyltransferase1) in Tgfb3-Cre-expressing mice resulted in an aberrant postnatal airway phenotype characterized by marked goblet cell metaplasia, decreased Clara cell number and increase in ciliated cells. The presence of the same phenotype in mice in which the Notch transcriptional effector Rbpjk was deleted indicated the involvement of the canonical Notch pathway. Lineage study in vivo suggested that goblet cells originated from a subpopulation of Clara cells largely present in proximal airways in which Notch was disrupted. The phenotype was confirmed by a panel of goblet cell markers, showed no changes in cell proliferation or altered expression of proinflammatory cytokines and was associated with significant downregulation of the bHLH transcriptional repressor Hes5. Luciferase reporter analysis suggested that Notch directly repressed MUC5AC transcription in lung epithelial cells. The data suggested that during postnatal life Notch is required to prevent Clara cells from differentiating into goblet cells.

Serum vascular endothelial growth factor/soluble vascular endothelial growth factor receptor 1 ratio is an independent prognostic marker in pancreatic cancer.

Objectives: Tumor angiogenesis is the consequence of an imbalance between positive and negative angiogenic regulatory factors. We sought to determine the role of pretreated serum angiogenic factors, including vascular endothelial growth factor (VEGF), placental growth factor (PlGF), and soluble vascular endothelial growth factor receptor 1 (sVEGFR-1), in predicting clinical outcome in patients with pancreatic cancer. Methods: We assessed pretreated serum VEGF, PlGF, and sVEGFR-1 levels in 92 patients with pancreatic adenocarcinoma and 60 healthy control subjects using an enzyme-linked immunosorbent assay. The correlation between these angiogenesis-related factors and clinicopathologic factors, including staging and overall survival, was analyzed. Results: Serum levels of VEGF, PlGF, and sVEGFR-1 were significantly higher in patients with pancreatic cancer compared with those in controls (583.8 ± 559.5 vs 187.63 ± 393.32, 17.65 ± 7.34 vs 10.93 ± 1.21, and 50.94 ± 51.17 vs 15.55 ± 1.98 pg/mL, respectively; P < 0.0001). A reverse correlation was observed between sVEGFR-1 level and the advance of tumor stage. Cox regression analysis showed that the VEGF/sVEGFR-1 ratio was an independent predictor for pancreatic cancer survival. Higher VEGF/sVEGFR-1 ratio was significantly correlated with poor outcome in patents with pancreatic cancer. Conclusions: Vascular endothelial growth factor/sVEGF-1 ratio is an independent prognostic factor for survival in pancreatic cancer. Its significance should be assessed when considering antiangiogenic therapy in treating pancreatic cancer patients.

Congenital intracranial teratoma

Congenital intracranial teratoma is a rare disease. A fetus with a congenital intracranial teratoma presenting with a disproportionately enlarged head at 27 weeks gestation is presented. Prenatal ultrasonography and fetal magnetic resonance imaging demonstrate a huge, heterogenous intracranial mass in the left supratentorial region, with the left cerebral hemisphere being compressed and flattened. The infant died of respiratory failure within 24 hours of birth at 28 weeks gestation. On postmortem examination the histologic report revealed an immature teratoma. Fetal MRI is helpful in the prenatal diagnosis and evaluation of intracranial tumor.

Excess Soluble fms-Like Tyrosine Kinase 1 and Low Platelet Counts in Premature Neonates of Preeclamptic Mothers

Objective. To investigate the relationship of neonatal platelet count and preeclampsia to levels of soluble fms-like tyrosine kinase 1 (sFlt-1), placental growth factor (PlGF), and vascular endothelial growth factor (VEGF) in the cord blood of preterm infants. Methods. Sixty-nine preterm infants with a gestational age between 26 and 37 weeks at birth were enrolled. sFlt-1, PlGF, and VEGF levels in the cord blood of preterm neonates, with or without maternal preeclampsia, were measured using a standardized sandwich enzyme-linked immunosorbent assay method. Results. Infants with maternal preeclampsia had higher cord blood sFlt-1 but lower PlGF and VEGF levels. There was a significantly positive relationship between neonatal platelet count and birth weight and a significantly negative relationship between neonatal platelet count and cord blood sFlt-1 levels. Multiple regression analysis revealed that only birth weight and cord blood sFlt-1 levels were independently related to neonatal platelet count, whereas maternal preeclampsia, gestational age (GA), and small for GA (SGA) were not related. Neonates with thrombocytopenia had higher cord blood sFlt-1 levels but lower birth weight. A significant correlation was also found between birth weight and cord blood sFlt-1 levels. Multiple regression with birth weight as the dependent variable found that only GA and cord blood sFlt-1 levels were independently related. Furthermore, infants with high cord blood sFlt-1 were more likely to have lower platelet count and maternal preeclampsia, be SGA, and have a trend toward lower birth weight. Conclusion. Excess sFlt-1 may play an important role in the development of maternal preeclampsia- induced neonatal thrombocytopenia, and SGA.

Neonatal Sepsis: A 6-Year Analysis in a Neonatal Care Unit in Taiwan

BACKGROUND Neonatal sepsis is the most serious problem in neonatal intensive care, resulting in significant morbidity and mortality. We evaluated the causative pathogen, drug sensitivity, hematological parameters, clinical course and mortality rate of neonatal sepsis in a Taiwanese medical center and compared our results to those of previous studies conducted in Taiwan. METHODS Neonates admitted to the neonatal intensive care unit (NICU) at National Taiwan University Hospital (NTUH) between January 2001 and December 2006 were included in this study. Patients were divided into early-onset sepsis and late-onset sepsis groups if their culture tested positive within the first 7 days of life or later, respectively. RESULTS A total of 109 episodes of sepsis were identified in 100 neonates. The incidence of sepsis was 4.06% among all NICU admissions. Most neonates with early-onset sepsis were term infants, while very low birth weight (VLBW) and preterm infants accounted for the majority of cases of late-onset sepsis. In early-onset sepsis, the most common pathogens responsible included group B streptococci (GBS) (36%) and Escherichia coli (E. coli) (26%). GBS was associated with more meningitis involvement but lower incidence of mortality compared with E. coli. The most common causative microorganisms in late-onset sepsis were coagulase-negative staphylococci (CONS) (40%) and Candida (15%). The sepsis-related mortality rates were higher in early-onset sepsis (10%) than in late-onset sepsis (7%). CONCLUSION Unlike previous reports from Taiwan, in the present study, GBS was found to be the leading pathogen in early-onset sepsis. GBS screening and intrapartum antibiotic prophylaxis guidelines should be used in Taiwan to prevent early neonatal sepsis. The most common causative microorganisms of late-onset sepsis were CONS and Candida species. Candida parapsilosis was associated with a high mortality rate.