BapE DNA endonuclease induces an apoptotic-like response to DNA damage in Caulobacter

In the presence of extensive DNA damage, eukaryotes activate endonucleases to fragment their chromosomes and induce apoptotic cell death. Apoptotic-like responses have recently been described in bacteria, but primarily in specialized mutant backgrounds, and the factors responsible for DNA damage-induced chromosome fragmentation and death have not been identified. Here we find that wild-type Caulobacter cells induce apoptotic-like cell death in response to extensive DNA damage. The bacterial apoptosis endonuclease (BapE) protein is induced by damage but not involved in DNA repair itself, and mediates this cell fate decision. BapE fragments chromosomes by cleaving supercoiled DNA in a sequence-nonspecific manner, thereby perturbing chromosome integrity both in vivo and in vitro. This damage-induced chromosome fragmentation pathway resembles that of eukaryotic apoptosis. We propose that damage-induced programmed cell death can be a primary stress response for some bacterial species, providing isogenic bacterial communities with advantages similar to those that apoptosis provides to multicellular organisms.Cell survival depends on the reliable transmission of intact genomes to daughter cells. When DNA is damaged, broken DNA must be accurately repaired to protect progeny from the aberrant transmission of incorrect genetic information. What do cells do if DNA damage accumulates beyond repair? In animal cells, DNA damage activates a p53-dependent cell cycle checkpoint that stimulates repair in the presence of low levels of damage and induces apoptotic cell death in the presence of high levels of damage (1, 2). By contrast, unicellular organisms such as bacteria were generally thought to simply arrest division upon DNA damage (3). Recent studies have suggested that Escherichia coli can undergo an apoptotic-like response to bactericidal antibiotics, including those that cause DNA damage (4, 5). However, similar effects were also observed with non–DNA-damaging drugs, such that the relatedness of the apoptotic response to DNA damage itself remained unclear (4, 5). Furthermore, the factors that mediate the chromosome fragmentation observed during bacterial apoptosis remained unidentified.Here we focus on the DNA damage response of Caulobacter crescentus because it lacks known lesion bypass pathways for copying extremely damaged DNA (6) and it has a eukaryotic-like cell cycle in which it replicates its DNA once and only once per cell division (7). Although the DNA damage response is less well characterized in Caulobacter than in other bacteria such as E. coli (8), a recent study identified SidA as an early SOS-induced division inhibitor in C. crescentus (9). However, SidA was found to only partially suppress damage-induced division (9), suggesting the existence of additional regulators of the C. crescentus DNA damage response. Here we demonstrate that wild-type Caulobacter cells undergo an apoptotic-like response to extensive DNA damage. We also identify BapE as a unique DNA endonuclease that is induced by the SOS DNA damage response pathway and leads to DNA fragmentation both in vivo and in vitro.     

Distinct and similar patterns of emotional development in adolescents and young adults

Adolescence is a developmental period of increased sensitivity to social emotional cues, but it is less known whether young adults demonstrate similar social emotional sensitivity. The current study tested variation in reaction times to emotional face cues during different phases of emotional development. Ex-Gaussian parameters mu, sigma, and tau were computed, in addition to mean, median and standard deviation (SD) in reaction times (RT) during an emotional go/nogo-paradigm with fearful, happy, and calm facial expressions in 377 participants, 6–30 years of age. Across development, mean RT showed slowing to fearful facial expressions relative to both calm and happy facial cues, but mu revealed that this pattern was specific to adolescence. In young adulthood, increased variability to fearful expressions relative to both happy and calm ones was captured by SD and tau. The findings that adolescents had longer response latencies to fearful faces, whereas young adults demonstrated greater response variability to fearful faces, together reflect how social emotional processing continues to evolve from adolescence into early adulthood. The findings suggest that young adulthood is also a vulnerable period for processing social emotional cues that ultimately may be important to better understand why different psychopathologies emerge in early adulthood.     

High-carbohydrate/low-protein-induced hyperinsulinemia does not improve protein balance in children after cardiac surgery

ObjectiveIn pediatric cardiac surgery, fluid-restricted low-protein (LoProt) diets account for cumulative protein deficits with increased morbidity. In this setting, we aimed to inhibit proteolysis by a high-carbohydrate (HiCarb)-intake–induced hyperinsulinemia and improve protein balance.MethodsThe effect of a HiCarb/LoProt (glucose 10 mg · kg^?1 · min^?1/protein 0.7 g · kg^?1 · d^?1) versus a normal-carbohydrate (NormCarb)/LoProt (glucose 7.5 mg · kg^?1 · min^?1/protein 0.3 g · kg^?1 · d^?1) enteral diet on whole-body protein breakdown and balance was compared in a prospective, randomized, single-blinded trial in 24 children after cardiac surgery. On the second postoperative day, plasma insulin and amino acid concentrations, protein breakdown (endogenous rate of appearance of valine), protein synthesis (non-oxidative disposal of valine), protein balance, and the rate of appearance of urea were measured by using an isotopic infusion of [1-¹³C]valine and [¹⁵N₂]urea.ResultsThe HiCarb/LoProt diet led to a serum insulin concentration that was three times higher than the NormCarb/LoProt diet (596 pmol/L, 80–1833, and 198 pmol/L, 76–1292, respectively, P = 0.02), without differences in plasma glucose concentrations. There were no differences in plasma amino acid concentrations, non-oxidative disposal of valine, and endogenous rate of appearance of valine between the groups, with a negative valine balance in the two groups (?0.65 μmol · kg^?1 · min^?1, ?1.91 to 0.01, and ?0.58 μmol · kg^?1 · min^?1, ?2.32 to ?0.07, respectively, P = 0.71). The serum cortisol concentration in the HiCarb/LoProt group was lower compared with the NormCarb/LoProt group (204 nmol/L, 50–544, and 532 nmol/L, 108–930, respectively, P = 0.02).ConclusionIn children with fluid restriction after cardiac surgery, a HiCarb/LoProt diet compared with a NormCarb/LoProt diet stimulates insulin secretion but does not inhibit proteolysis further and therefore cannot be advocated for this purpose.     

Coping in adult patients with severe haemophilia

An adequate use of coping strategies could help patients to deal with disease‐related stress. The study aim was to explore coping behaviour in adult patients with severe haemophilia and its possible determinants. Coping was assessed through three basic dimensions (task‐oriented, emotion‐oriented and avoidance coping), using the short version of the Coping Inventory for Stressful Situations (CISS‐21). Patients' scores were compared with Dutch working men (N = 374), according to three categories: low use (<P25 of normal), average use (P25–P75) and high use (>P75). Determinants were measured using questionnaires on activities (Haemophilia Activities List), participation (Impact on Participation and Autonomy Questionnaire), physical functioning [physical component of the Dutch Arthritis Impact Measurement Scales‐2 (D‐AIMS2)] and socio‐psychological health (psychological component of the D‐AIMS2). In total, 86 adults with severe haemophilia (FVIII/IX<1%) were included. The median age was 38 years (range: 18–68) with 85% affected with haemophilia A and 75% using prophylaxis. Patients with haemophilia used task‐oriented coping as frequently as the control group (P = 0.13); but used significantly less emotion‐oriented coping (57% vs. 25%, P < 0.05) and avoidance coping (P < 0.05). Emotion‐oriented coping showed a strong correlation with socio‐psychological health (r = 0.67) and weak correlations with participation (r = 0.32) and social interaction (r = 0.29). Other associations of coping strategies with patient characteristics of health status could not be demonstrated. Overall, patients predominantly used the task‐oriented approach to deal with their disease; the use of this strategy was comparable to the control group. Having a poor psychological health, less social interaction and/or less participation in daily life was associated with an increased use of emotion‐oriented coping.     

Metabolic modulation during intestinal fibrosis

Intestinal fibrosis is one of the biggest challenges in the therapeutic management of inflammatory bowel diseases (IBD). Patients with Crohn's disease, in particular, suffer from fibrotic complications, which are manifested by the clinical stenosis of the bowel. Although fibrosis is caused by recurrent episodes of inflammation and wound healing, current therapies for IBD do not seem to reduce the incidence of stenosis, suggesting that inflammation‐independent mechanisms also contribute to intestinal fibrogenesis. The lack of anti‐fibrotic therapies for IBD and the huge burden this complication places on patients has prompted us to redirect inflammation research toward understanding the mechanisms that drive gut fibrosis. Based on data from other fibroproliferative diseases, metabolic modifications are increasingly recognized as pathogenic processes that may generate new therapeutic opportunities. These metabolic alterations result from a switch in the cellular metabolism of activated fibroblasts, which are the key mediator cells of fibrosis. Here, we review the metabolic changes associated with fibrotic disease and summarize the evidence of a metabolic shift during intestinal fibrosis.     

Human rotavirus vaccine RotarixTM provides protection against diverse circulating rotavirus strains in African infants: a randomized controlled trial

ABSTRACT: BACKGROUND: Rotaviruses are the most important cause of severe acute gastroenteritis worldwide in children <5 years of age. The human, G1P[8] rotavirus vaccine RotarixTM significantly reduced severe rotavirus gastroenteritis episodes in a Phase III clinical trial conducted in infants in South Africa and Malawi. This paper examines rotavirus vaccine efficacy in preventing severe rotavirus gastroenteritis, during infancy, caused by the various G and P rotavirus types encountered during the first rotavirus-season. METHODS: Healthy infants aged 5-10 weeks were enrolled and randomized into three groups to receive either two (10 and 14 weeks) or three doses of RotarixTM (together forming the pooled RotarixTM group) or three doses of placebo at a 6,10,14-week schedule. Weekly home visits were conducted to identify gastroenteritis episodes. Rotaviruses were detected by ELISA and genotyped by RT-PCR and nucleotide sequencing. The percentage of infants with severe rotavirus gastroenteritis caused by the circulating G and P types from 2 weeks post-last dose until one year of age and the corresponding vaccine efficacy was calculated with 95 % CI. RESULTS: Overall, 4939 infants were vaccinated and 4417 (pooled RotarixTM = 2974; placebo = 1443) were included in the per protocol efficacy cohort. G1 wild-type was detected in 23 (1.6 %) severe rotavirus gastroenteritis episodes from the placebo group. This was followed in order of detection by G12 (15 [1 %] in placebo) and G8 types (15 [1 %] in placebo). Vaccine efficacy against G1 wild-type, G12 and G8 types were 64.1 % (95 % CI: 29.9 %; 82 %), 51.5 % (95 % CI:-6.5 %; 77.9 %) and 64.4 % (95 % CI: 17.1 %; 85.2 %), respectively. Genotype P[8] was the predominant circulating P type and was detected in 38 (2.6 %) severe rotavirus gastroenteritis cases in placebo group. The remaining circulating P types comprised of P[4] (20 [1.4 %] in placebo) and P[6] (13 [0.9 %] in placebo). Vaccine efficacy against P[8] was 59.1 % (95 % CI: 32.8 %; 75.3 %), P[4] was 70.9 % (95 % CI: 37.5 %; 87.0 %) and P[6] was 55.2 % (95 % CI: -6.5 %; 81.3 %) CONCLUSIONS: RotarixTM vaccine demonstrated efficacy against severe gastroenteritis caused by diverse circulating rotavirus types. These data add to a growing body of evidence supporting heterotypic protection provided by RotarixTM. Trial registration number NCT00241644.     

1Long-term renal outcome in patients with malignant hypertension: a retrospective cohort study

ABSTRACT: BACKGROUND: Malignant hypertension is frequently complicated by renal insufficiency. Although the survival of this hypertensive emergency has improved, recent data on renal outcome and its predictors are lacking. We assessed renal outcome and its predictors in patients with malignant hypertension. METHODS: Retrospective analysis of patients admitted with malignant hypertension in Amsterdam, the Netherlands between August 1992-January 2010. Follow-up data on vital status, renal function and blood pressure (BP) were obtained from the outpatient department and from general practitioners. The primary composite endpoint was end-stage renal disease (ESRD) defined as the start of kidney replacement therapy (KRT) or [greater than or equal to] 50 % decline of estimated glomerular filtration rate (eGFR). The secondary endpoint was all cause mortality. RESULTS: A total of 120 patients admitted with malignant hypertension were included. After a median follow-up period of 67 months (IQR 28 to 108 months) the primary endpoint was reached by 37 (31 %) patients, whereas 18 patients (15 %) reached the secondary endpoint. Twenty-nine (24 %) patients started KRT and 8 patients (7 %) had an eGFR decline [greater than or equal to] 50 %. After the acute phase (> 3 months after admission), initial serum creatinine and follow-up BP were the main predictors of future ESRD with hazard ratios of 6.1 (95 % CI, 2.2-17) for patients with initial serum creatinine [greater than or equal to] 175 mumol /L and 4.3 (95 % CI, 1.4-14) for patients with uncontrolled hypertension. CONCLUSIONS: Progressive renal function decline leading to ESRD remains a major threat to patients with malignant hypertension. BP control during follow-up was an important modifiable predictor of renal outcome.