Fine-scale time-lapse analysis of the biphasic, dynamic behaviour of the two Vibrio cholerae chromosomes

Using fluorescent repressor-operator systems in live cells, we investigated the dynamic behaviour of chromosomal origins in Vibrio cholerae, whose genome is divided between two chromosomes. We have developed a method of analysing fine-scale motion in the curved co-ordinate system of vibrioid bacteria. Using this method, we characterized two different modes of chromosome behaviour corresponding to periods between segregation events and periods of segregation. Between segregation events, the origin positions are not fixed but rather maintained within ellipsoidal caged domains, similar to eukaryotic interphase chromosome territories. These domains are approximately 0.4 µm wide and 0.6 µm long, reflecting greater restriction in the short axis of the cell. During segregation, movement is directionally biased, speed is comparable between origins, and cell growth can account for nearly 20% of the motion observed. Furthermore, the home domain of each origin is positioned by a different mechanism. Specifically, the oriCI domain is maintained at a constant actual distance from the pole regardless of cell length, while the oriCII domain is maintained at a constant relative position. Thus the actual position of oriCII varies with cell length. While the gross behaviours of the two origins are distinct, their fine-scale dynamics are remarkably similar, indicating that both experience similar microenvironments

Pengaruh Molar Rasio Tetracalcium Phosphate Dan Dicalcium Phosphate Dan Penambahan Chitosan Sebagai Gelling Agent Dalam Sintesis Pasta Calcium Phosphate Cement

Bone cement berbasis calcium phosaphate banyak digunakan dalam aplikasi kedokteran karena memiliki in-situ-setting ability, osteoconductivity, dan bone-replacement capability yang baik. Akan tetapi, calcium phosphate cement memiliki keterbatasan yaitu setting time yang lama, mudah washout, dan memiliki strength yang rendah. Oleh karena itu, pada studi ini penulis mencoba memodifikasi sifat dari calcium phospate cement tersebut dengan memodifikasi molar rasio tetracalcium phosphate (TTCP) dan dicalcium phosphate (DCPA), dan menambahkan chitosan sebagai gelling agent. Modifikasi molar rasio bertujuan untuk menurunkan setting time, sedangkan penambahan chitosan bertujuan untuk meningkatkan washout resistance, mempercepat pertumbuhan apatit dan mempercepat setting time. Modifikasi molar rasio tetracalcium phosphate (TTCP) dan dicalcium phosphate (DCPA) dari 1:1 menjadi 1:2 menunjukan penurunan setting time yang signifikan dari 30 menit menjadi 12 menit untuk sampel tanpa penambahan chitosan, dan untuk sampel dengan penambahan chitosan terjadi penurunan setting time dari 28 menit menjadi 8 menit. Penambahan chitosan terbukti efektif mempercepat setting time sekitar 2-4 menit, mempercepat pertumbuhan apatit dan dapat meningkatkan washout resistance semua sampel

Updating existing emotional memories involves the frontopolar/orbitofrontal cortex in ways that acquiring new emotional memories does not

In life, we must often learn new associations to people, places, or things we already know. The current fMRI study investigated the neural mechanisms underlying emotional memory updating. Nineteen participants first viewed negative and neutral pictures and learned associations between those pictures and other neutral stimuli, such as neutral objects and encoding tasks. This initial learning phase was followed by a memory updating phase, during which participants learned picture-location associations for old pictures (i.e., pictures previously associated with other neutral stimuli) and new pictures (i.e., pictures not seen in the first phase). There was greater frontopolar/orbito-frontal (OFC) activity when people learned picture–location associations for old negative pictures than for new negative pictures, but frontopolar OFC activity did not significantly differ during learning locations of old versus new neutral pictures. In addition, frontopolar activity was more negatively correlated with the amygdala when participants learned picture–location associations for old negative pictures than for new negative or old neutral pictures. Past studies revealed that the frontopolar OFC allows for updating the affective values of stimuli in reversal learning or extinction of conditioning [e.g., Izquierdo, A., & Murray, E. A. Opposing effects of amygdala and orbital PFC lesions on the extinction of instrumental responding in macaque monkeys. European Journal of Neuroscience, 22, 2341–2346, 2005]; our findings suggest that it plays a more general role in updating associations to emotional stimuli

Cesarean delivery, preterm birth and risk of food allergy : nationwide Swedish cohort study of over 1 million children

Background & Objectives: Little is known about early life risk factors for food allergy in children. We examined the association between perinatal characteristics and future risk of food allergy in offspring. Methods: This nationwide Swedish cohort study of 1,086,378 children born in Sweden in 2001-2012 used prospectively recorded data from health care registers. Using Cox regression, we estimated hazard ratios (HRs) with 95% confidence intervals (CIs) for the association between perinatal characteristics (e.g. caesarean delivery, preterm birth) and food allergy as defined by diagnoses in the National Patient Register, adjusting for infant sex and maternal factors (age at delivery, country of birth, parity, smoking, body mass index and asthma/pulmonary disease). Results: During the 13-year follow-up, 26,732 children (2.5%) were diagnosed with food allergy. Food allergy was positively associated with caesarean delivery (HR=1.21; 95%CI=1.18-1.25), large for gestational age (HR=1.15; 95%CI=1.10-1.19) and low 5-minute Apgar score (HR=1.22, 95CI=1.10-1.36) but negatively associated with very preterm birth (<32 weeks of gestation: HR=0.74; 95%CI=0.56-0.98). No association was found between food allergy and moderately preterm birth, low birth weight or small for gestational age. Risk estimates were similar when the outcome was restricted to two records of diagnosed food allergy. In 1,000 children undergoing caesarean delivery, an extra 5 developed food allergy compared with the reference group, suggesting that 17% of food allergy in children born with caesarean delivery can be explained by this exposure (attributable fraction). Conclusions: Caesarean delivery was associated with increased risk of food allergy, whereas very preterm birth with decreased risk.NoneAccepte

Nanoscale antiadhesion properties of sophorolipid-coated surfaces against pathogenic bacteria

A current challenge in nanomedicine is to develop innovative strategies to fight infections caused by multiresistant bacterial pathogens. A striking example is antiadhesion therapy, which represents an attractive alternative to antibiotics to prevent and treat biofilm-associated infections on medical devices. By means of single-cell force nanoscopy, we demonstrate that sophorolipid (SL) biosurfactants feature unusually strong antiadhesion properties against Staphylococcus aureus and Escherichia coli, two nosocomial pathogens involved in catheter-related infections, which represent a major public health problem worldwide. We find that the nanoscale adhesion forces of single bacteria are much weaker on SL monolayers than on abiotic alkanethiol monolayers. The remarkable antifouling efficacy of SL-surfaces is likely to involve repulsive hydration forces associated with sophorose headgroups. We also show that, owing to their surfactant properties, soluble SLs block bacterial adhesion forces towards abiotic surfaces. Collectively, our single-cell experiments demonstrate that sophorolipids exhibit strong and versatile antiadhesion properties, making them promising candidates to design anti-infective biomaterials