Impact of Daily Thermocycles on Hatching Rhythms, Larval Performance and Sex Differentiation of Zebrafish

In the wild, water temperature cycles daily: it warms up after sunrise, and cools rapidly after sunset. Surprisingly, the impact of such daily thermocycles during the early development of fish remains neglected. We investigated the influence of constant vs daily thermocycles in zebrafish, from embryo development to sexual differentiation, by applying four temperature regimens: two constant (24°C and 28°C) and two daily thermocycles: 28:24°C, TC (thermophase coinciding with daytime, and cryophase coinciding with night-time) and 24:28°C, CT (opposite to TC) in a 12:12 h light:dark cycle (LD). Embryo development was temperature-dependent but enhanced at 28°C and TC. Hatching rhythms were diurnal (around 4 h after lights on), but temperature- and cycle-sensitive, since hatching occurred sooner at 28°C (48 hours post fertilization; hpf) while it was delayed at 24°C (96 hpf). Under TC, hatching occurred at 72 hpf, while under CT hatching displayed two peaks (at 70 hpf and 94 hpf). In constant light (LL) or darkness (DD), hatching rhythms persisted with tau close to 24 h, suggesting a clock-controlled "gating" mechanism. Under 28°C or TC, larvae showed the best performance (high growth and survival, and low malformations). The sex ratio was strongly influenced by temperature, as the proportion of females was higher in CT and TC (79 and 83% respectively), contrasting with 28°C and 24°C, which led to more males (83 and 76%). Ovarian aromatase (cyp19a) expression in females was highest in TC and CT (6.5 and 4.6 fold higher than at 28°C, respectively); while anti-müllerian hormone (amh) expression in males increased in testis at 24°C (3.6 fold higher compared to TC) and particularly at 28°C (14.3 fold increase). Taken together, these findings highlight the key role of environmental cycles during early development, which shaped the daily rhythms in fish embryo and larvae, and ultimately influenced sex differentiation

The histone deacetylase inhibitor Trichostatin A modulates CD4+ T cell responses

BACKGROUND: Histone deacetylase inhibitors (HDACIs) induce hyperacetylation of core histones modulating chromatin structure and affecting gene expression. These compounds are also able to induce growth arrest, cell differentiation, and apoptotic cell death of tumor cells in vitro as well as in vivo. Even though several genes modulated by HDAC inhibition have been identified, those genes clearly responsible for the biological effects of these drugs have remained elusive. We investigated the pharmacological effect of the HDACI and potential anti-cancer agent Trichostatin A (TSA) on primary T cells. METHODS: To ascertain the effect of TSA on resting and activated T cells we used a model system where an enriched cell population consisting of primary T-cells was stimulated in vitro with immobilized anti-CD3/anti-CD28 antibodies whilst exposed to pharmacological concentrations of Trichostatin A. RESULTS: We found that this drug causes a rapid decline in cytokine expression, accumulation of cells in the G(1 )phase of the cell cycle, and induces apoptotic cell death. The mitochondrial respiratory chain (MRC) plays a critical role in the apoptotic response to TSA, as dissipation of mitochondrial membrane potential and reactive oxygen species (ROS) scavengers block TSA-induced T-cell death. Treatment of T cells with TSA results in the altered expression of a subset of genes involved in T cell responses, as assessed by microarray gene expression profiling. We also observed up- as well as down-regulation of various costimulatory/adhesion molecules, such as CD28 and CD154, important for T-cell function. CONCLUSIONS: Taken together, our findings indicate that HDAC inhibitors have an immunomodulatory potential that may contribute to the potency and specificity of these antineoplastic compounds and might be useful in the treatment of autoimmune disorders

Prognosis of neonatal tetanus in the modern management era: an observational study in 107 Vietnamese infants.

OBJECTIVES: Most data regarding prognosis in neonatal tetanus originates from regions where limited resources have historically impeded management. It is not known whether recent improvements in critical care facilities in many low and middle income countries have affected indicators of poor prognosis in neonatal tetanus. We aimed to determine the factors associated with worse outcome in a Vietnamese hospital with neonatal intensive care facilities. METHODS: Data was collected from 107 cases of neonatal tetanus. Clinical features on admission were analyzed against mortality and a combined endpoint of 'death or prolonged hospital stay'. RESULTS: Multivariable analysis showed that only younger age (OR for mortality 0.69, 95% CI 0.48 to 0.98) and lower weight (OR for mortality 0.06, 95% CI 0.01 to 0.54) were significantly associated with both the combined end point and death. Shorter period of onset (OR 0.94 95% CI 0.9 to 0.97), raised white cell count (OR 1.17, 95% CI 1.02 to 1.35), and time between first symptom and admission (OR 3.77, 95% CI 1.14 to1 2.51) were also indicators of mortality. CONCLUSIONS: Risk factors for poor outcome in neonatal tetanus in a setting with critical care facilities include younger age, lower weight, delay in admission and leukocytosis

Prognosis of neonatal tetanus in the modern management era: an observational study in 107 Vietnamese infants.

OBJECTIVES: Most data regarding prognosis in neonatal tetanus originates from regions where limited resources have historically impeded management. It is not known whether recent improvements in critical care facilities in many low and middle income countries have affected indicators of poor prognosis in neonatal tetanus. We aimed to determine the factors associated with worse outcome in a Vietnamese hospital with neonatal intensive care facilities. METHODS: Data was collected from 107 cases of neonatal tetanus. Clinical features on admission were analyzed against mortality and a combined endpoint of 'death or prolonged hospital stay'. RESULTS: Multivariable analysis showed that only younger age (OR for mortality 0.69, 95% CI 0.48 to 0.98) and lower weight (OR for mortality 0.06, 95% CI 0.01 to 0.54) were significantly associated with both the combined end point and death. Shorter period of onset (OR 0.94 95% CI 0.9 to 0.97), raised white cell count (OR 1.17, 95% CI 1.02 to 1.35), and time between first symptom and admission (OR 3.77, 95% CI 1.14 to1 2.51) were also indicators of mortality. CONCLUSIONS: Risk factors for poor outcome in neonatal tetanus in a setting with critical care facilities include younger age, lower weight, delay in admission and leukocytosis

Long-term outcome in survivors of neonatal tetanus following specialist intensive care in Vietnam

Background: Neonatal tetanus continues to occur in many resource-limited settings but there are few data regarding long-term neurological outcome from the disease, especially in settings with critical care facilities. Methods: We assessed long-term outcome following neonatal tetanus in infants treated in a pediatric intensive care unit in southern Vietnam. Neurological and neurodevelopmental testing was performed in 17 survivors of neonatal tetanus and 18 control children from the same communities using tools previously validated in Vietnamese children. Results: The median age of children assessed was 36 months. Eight neonatal tetanus survivors and 9 community control cases aged p = 0.05) with a significantly lower cognitive domain score (3 (IQR 2–6) severe disease vs 7 (IQR 7–8) mild disease, p = 0.02). Conclusions: Neonatal tetanus is associated with long-term sequelae in those with severe disease. In view of these findings, prevention of neonatal tetanus should remain a priority.</p

Antibiotic use and prescription and its effects on Enterobacteriaceae in the gut in children with mild respiratory infections in Ho Chi Minh City, Vietnam. A prospective observational outpatient study

Background and objectives Treatment guidelines do not recommend antibiotic use for acute respiratory infections (ARI), except for streptococcal pharyngitis/tonsillitis and pneumonia. However, antibiotics are prescribed frequently for children with ARI, often in absence of evidence for bacterial infection. The objectives of this study were 1) to assess the appropriateness of antibiotic prescriptions for mild ARI in paediatric outpatients in relation to available guidelines and detected pathogens, 2) to assess antibiotic use on presentation using questionnaires and detection in urine 3) to assess the carriage rates and proportions of resistant intestinal Enterobacteriaceae before, during and after consultation. Materials and methods Patients were prospectively enrolled in Children’s Hospital 1, Ho Chi Minh City, Vietnam and diagnoses, prescribed therapy and outcome were recorded on first visit and on follow-up after 7 days. Respiratory bacterial and viral pathogens were detected using molecular assays. Antibiotic use before presentation was assessed using questionnaires and urine HPLC. The impact of antibiotic usage on intestinal Enterobacteriaceae was assessed with semi-quantitative culture on agar with and without antibiotics on presentation and after 7 and 28 days. Results A total of 563 patients were enrolled between February 2009 and February 2010. Antibiotics were prescribed for all except 2 of 563 patients. The majority were 2nd and 3rd generation oral cephalosporins and amoxicillin with or without clavulanic acid. Respiratory viruses were detected in respiratory specimens of 72.5% of patients. Antibiotic use was considered inappropriate in 90.1% and 67.5%, based on guidelines and detected pathogens, respectively. On presentation parents reported antibiotic use for 22% of patients, 41% of parents did not know and 37% denied antibiotic use. Among these three groups, six commonly used antibiotics were detected with HPLC in patients’ urine in 49%, 40% and 14%, respectively. Temporary selection of 3rd generation cephalosporin resistant intestinal Enterobacteriaceae during antibiotic use was observed, with co-selection of resistance to aminoglycosides and fluoroquinolones. Conclusions We report overuse and overprescription of antibiotics for uncomplicated ARI with selection of resistant intestinal Enterobacteriaceae, posing a risk for community transmission and persistence in a setting of a highly granular healthcare system and unrestricted access to antibiotics through private pharmacies. Registration This study was registered at the International Standard Randomised Controlled Trials Number registry under number ISRCTN32862422: http://www.isrctn.com/ISRCTN3286242