Molecular characterization of a family of cold-shock proteins of Lactococcus lactis

Lactic acid bacteria (LAB) are widely used as starter cultures in fermentation processes. The stress response of LAB during different industrial processes, and during low-temperature conditions in particular, requires a better understanding. For that reason a research project on the cold adaptation of Lactococcus lactis MG1363, a model LAB strain, was initiated. Research focused on the identification and characterization of a family of five csp genes, named cspA, cspB, cspC, cspD and cspE , encoding highly similar cold-shock proteins (CSPs; 65-85% identity). On the L. lactis MG1363 chromosome two tandem groups of csp genes ( cspA/cspB and cspC/cspD ) were identified, whereas cspE was found as a single gene.Transcription analysis showed that cspE is the only non-cold-induced csp gene, whereas the other csp genes are induced 10- to 40-fold at different times after cold shock. The 7-kDa CSPs, corresponding to the csp genes of L. lactis MG1363, were the highest induced proteins upon cold shock to 10°C as was shown by two-dimensional gel electrophoresis. Using the nisin-inducible expression system CspB, CspD and CspE could be overproduced to high levels. For CspA and CspC limited overproduction was obtained, that could be explained by low stability of cspC mRNA and by low stability of CspA. For L. lactis NZ9000ΔAB (deleted in cspAB ) and NZ9000ΔABE (deleted in cspABE ) no differences in growth at normal and at low temperature were observed, compared to that of the wild-type strain L. lactis NZ9000. The deletion of csp genes was compensated by increased expression of the remaining csp genes. These data indicate that the expression of csp genes in L. lactis is regulated by a tightly controlled transcription network.When L. lactis cells were shocked to 10°C for 4 h the survival to freezing increased approximately 100-fold compared to mid-exponential phase cells grown at 30°C. L. lactis cells overproducing CspB, CspD or CspE at 30°C show a 2-10 fold increased survival after freezing compared to control cells. The adaptive response to freezing conditions by prior exposure to 10°C was significantly delayed in strain NZ9000ΔABE compared to strains NZ9000 and NZ9000ΔAB.In combination, these data indicate that 7-kDa CSPs of L. lactis enhance the survival capacity after freezing. CSPs either have a direct protective effect during freezing, e.g. by RNA stabilization, and/or induce other factors involved in the freeze-adaptive response. A group of strongly cold-induced 7-kDa proteins was also identified for Streptococcus thermophilus and, indeed, enhanced production of these proteins also coincided with increased survival to freezing of this bacterium.Using two-dimensional gel electrophoresis, induction of several (non-7 kDa) cold-induced proteins (CIPs) of L. lactis was observed upon overproduction of CSPs. Furthermore, several CIPs were no longer cold induced in the csp -deleted strains, which indicates that CSPs might activate the expression of certain CIPs. A selection of CIPs of L. lactis was identified and appears to be implicated in a variety of cellular processes, e.g. transcriptional and translational control, sugar metabolism and signal sensing. Furthermore, it was shown that the maximal glycolytic activity measured at 30°C increases (approximately 2.5-fold) upon incubation at 10°C for two to four h, a process for which protein synthesis is required. Based on their cold induction and involvement in cold adaptation of glycolysis, it is proposed that the CcpA/HPr control circuit regulates a (unidentified) factor involved in the increased glycolytic activity.The research described in this thesis contributes to the understanding of the response of lactic acid bacteria to low temperatures and might yield applications for dairy industry, especially with respect to fermentation performance and the survival of starter bacteria during freezing.</p

Maatregelen om vorstschade in grasland te voorkomen

In de nazomer kunnen al maatregelen genomen worden om de vorstschade in grasland te beperken

Variation in Surgical Treatment of Abdominal Aortic Aneurysms With Small Aortic Diameters in the Netherlands

Objective: To evaluate reasons to deviate from aneurysm diameter thresholds, and focus on the difference in how Dutch vascular surgical units (VSUs) perceive their deviation and their actual deviation. Background: Guidelines recommend surgical treatment for asymptomatic abdominal aortic aneurysms (AAAs) with a diameter of at least 55 mm for men and 50 mm for women. We evaluate reasons to deviate from these guidelines, and focus on the difference in how Dutch vascular surgical units (VSUs) perceive their deviation and their actual deviation. Methods: All patients undergoing elective AAA repair between 2013 and 2016 registered in the Dutch Surgical Aneurysm Audit (DSAA) were included. Surgery at diameters of <55 mm for men and <50 mm for women were considered guideline deviations. National deviation and hospital variation in deviation were evaluated over time. Questionnaires were distributed among all Dutch VSUs, inquiring for acceptable reasons for guideline deviation. VSUs were asked to estimate the guideline deviation percentage in their hospital which was then compared with their DSAA percentage. Results: In all, 9039 patients were included. In 15%, we found guideline deviation, varying from 2% to 40% between VSUs. Over time, 21 VSUs were identified with a lower percentage of deviation than the national mean each year and 8 VSUs with a higher percentage. 44/60 VSUs completed the questionnaire. Most commonly reported reasons to deviate were concomitant large iliac diameter (91%) and saccular aneurysm (82%). The majority of the VSUs (77%) estimated their guideline deviation to be <5%. Eleven VSUs (25%) estimated their deviation concordant with their DSAA percentage, but 75% of VSUs underestimated their deviation. Conclusions: Dutch VSUs regularly deviate from the guidelines regarding aneurysm diameter, with variation between VSUs. Consensus exists amongst VSUs on acceptable reasons for guideline deviations; however, the majority underestimates their actual deviation percentage

Clustering of 27,525,663 death records from the United States based on health conditions associated with death: an example of big health data exploration

Background: Insight into health conditions associated with death can inform healthcare policy. We aimed to cluster 27,525,663 deceased people based on the health conditions associated with death to study the associations between the health condition clusters, demographics, the recorded underlying cause and place of death. Methods: Data from all deaths in the United States registered between 2006 and 2016 from the National Vital Statistics System of the National Center for Health Statistics were analyzed. A self-organizing map (SOM) was used to create an ordered representation of the mortality data. Results: 16 clusters based on the health conditions associated with death were found showing significant differences in socio-demographics, place, and cause of death. Most people died at old age (73.1 (18.0) years) and had multiple health conditions. Chronic ischemic heart disease was the main cause of death. Most people died in the hospital or at home. Conclusions: The prevalence of multiple health conditions at death requires a shift from disease-oriented towards person-centred palliative care at the end of life, including timely advance care planning. Understanding differences in population-based patterns and clusters of end-of-life experiences is an important step toward developing a strategy for implementing population-based palliative care

Changes in glycolytic activity of Lactococcus lactis induced by low temperature

The effects of low-temperature stress on the glycolytic activity of the lactic acid bacterium Lactococcus lactis were studied. The maximal glycolytic activity measured at 30°C increased approximately 2.5-fold following a shift from 30 to 10°C for 4 h in a process that required protein synthesis. Analysis of cold adaptation of strains with genes involved in sugar metabolism disrupted showed that both the phosphoenolpyruvate-dependent sugar phosphotransferase system (PTS) subunit HPr and catabolite control protein A (CcpA) are involved in the increased acidification at low temperatures. In contrast, a strain with the PTS subunit enzyme I disrupted showed increased acidification similar to that in the wild-type strain. This indicates that the PTS is not involved in this response whereas the regulatory function of 46-seryl phosphorylated HPr [HPr(Ser-P)] probably is involved. Protein analysis showed that the production of both HPr and CcpA was induced severalfold (up to two- to threefold) upon exposure to low temperatures. The las operon, which is subject to catabolite activation by the CcpA-HPr(Ser-P) complex, was not induced upon cold shock, and no increased lactate dehydrogenase (LDH) activity was observed. Similarly, the rate-limiting enzyme of the glycolytic pathway under starvation conditions, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), was not induced upon cold shock. This indicates that a factor other than LDH or GAPDH is rate determining for the increased glycolytic activity upon exposure to low temperatures. Based on their cold induction and involvement in cold adaptation of glycolysis, it is proposed that the CcpA-HPr(Ser-P) control circuit regulates this factor(s) and hence couples catabolite repression and cold shock response in a functional and mechanistic way

Core excitation in Coulomb breakup reactions

Within the pure Coulomb breakup mechanism, we investigate the one-neutron removal reaction of the type A(a,b$\gamma$)X with $^{11}$Be and $^{19}$C projectiles on a heavy target nucleus $^{208}$Pb at the beam energy of 60 MeV/nucleon. Our intention is to examine the prospective of using these reactions to study the structure of neutron rich nuclei. Integrated partial cross sections and momentum distributions for the ground as well as excited bound states of core nuclei are calculated within the finite range distorted wave Born approximation as well as within the adiabatic model of the Coulomb breakup. Our results are compared with those obtained in the studies of the reactions on a light target where the breakup proceeds via the pure nuclear mechanism. We find that the transitions to excited states of the core are quite weak in the Coulomb dominated process as compared to the pure nuclear breakup.Comment: Revtex format, five postscript figures included, to appear in Phys. Rev.

Health-related quality of life of children and their parents 2 years after critical illness

Background: Pediatric intensive care unit (PICU) survivors are at risk for prolonged morbidities interfering with daily life. The current study examined parent-reported health-related quality of life (HRQoL) in former critically ill children and parents themselves and aimed to determine whether withholding parenteral nutrition (PN) in the first week of critical illness affected children’s and parents’ HRQoL 2 years later. Methods: Children who participated in the pediatric early versus late parenteral nutrition in critical illness (PEPaNIC) trial and who were testable 2 years later (n = 1158) were included. Their HRQoL outcomes were compared with 405 matched healthy controls. At PICU admission, childre

Respiratory adverse effects of opioids for breathlessness: a systematic review and meta-analysis

Background: Previous studies have shown that opioids can reduce chronic breathlessness in advanced disease. However, physicians remain reluctant to prescribe opioids for these patients, commonly due to fear of respiratory adverse effects. Aim: To systematically review reported respiratory adverse effects of opioids in patients with advanced disease and chronic breathlessness. Methods: Pubmed, Embase, Cochrane central register of controlled trials, CINAHL, ClinicalTrials.gov and the reference lists of relevant systematic reviews were searched. Two independent researchers screened against predefined inclusion criteria and extracted data. Meta-analysis was conducted where possible. Results: We included 63 out of 1990 articles, describing 67 studies. Meta-analysis showed an increase in partial pressure of carbon dioxide (0.27 kPa; 95% CI 0.08 to 0.45) and no significant change in partial pressure of oxygen and oxygen saturation (both p>0.05). Non-serious respiratory depression (definition variable/not stated) was described in 4/1064 patients. One cancer patient pre-treated with morphine for pain needed temporary respiratory support following nebulized morphine for breathlessness (single case study). Conclusions: We found no evidence of significant or clinically relevant respiratory adverse effects of opioids for chronic breathlessness. Heterogeneity of design and study population, and low study quality are limitations. Larger studies designed to detect respiratory adverse effects are needed

Dynamical description of the breakup of one-neutron halo nuclei 11Be and 19C

We investigate the breakup of the one-neutron halo nuclei 11Be and 19C within a dynamical model of the continuum excitation of the projectile. The time evolution of the projectile in coordinate space is described by solving the three-dimensional time dependent Schroedinger equation, treating the projectile-target (both Coulomb and nuclear) interaction as a time dependent external perturbation. The pure Coulomb breakup dominates the relative energy spectra of the fragments in the peak region, while the nuclear breakup is important at higher relative energies. The coherent sum of the two contributions provides a good overall description of the experimental spectra. Cross sections of the first order perturbation theory are derived as a limit of our dynamical model. The dynamical effects are found to be of the order of 10-15% for the beam energies in the range of 60 - 80 MeV/nucleon. A comparison of our results with those of a post form distorted wave Born approximation shows that the magnitudes of the higher order effects are dependent on the theoretical model.Comment: 15 pages, ReVTeX, 5 figures, typos corrected, accepted for publication in Physical Review