Diagnosis of external ventricular catheter-associated infections

External ventricular drains are used to temporarily divert cerebrospinal fluid (CSF) from an obstructed ventricular system. External catheter-associated bacterial infection is a common complication in patients with ventricular drains. Diagnosing ventricular catheter-associated infection can be difficult because of the primary neurological condition of the patient and the occurrence of an inflammatory response in the CSF without infection. In this thesis we described the diagnostic accuracy of different tests for diagnosing external catheter-associated infection, identified the current diagnostic dilemmas and knowledge gaps and identified new, potentially sensitive and fast biomarkers for diagnosing CSF catheter-associated infection. We demonstrated that no single CSF, blood or microbiological measure can be used on its own to differentiate between an infection or sterile inflammation. CSF leukocyte count, percentage of polymorphonuclear cells and positive culture results are the most reliable parameters. A positive Gram stain is highly indicative for drain-associated infections but false negative results frequently occur. There is no incremental value of determining CSF and CSF to blood ratios of procalcitonin and lactate for diagnosing CSF catheter-associated infection.We demonstrated that there is no additional value of daily sampling for diagnosing catheter-associated infection and since it increases the risk of infection, daily sampling should not be performed. By daily sampling we obtained a time line which gave us an understanding on the progression of the researched parameters over time. CSF first showed signs of bacterial invasion prior to the occurrence of an infectious response. This observation can be a starting point for future research on earlier sensitive detection of catheter-associated infection

Maternal inheritance of twist and analysis of MAPK activation in embryos of the polychaete Annelid Platynereis dumerilii

In this study, we aimed to identify molecular mechanisms involved in the specification of the 4d (mesentoblast) lineage in Platynereis dumerilii. We employ RT-PCR and in situ hybridization against the Platynereis dumerilii twist homolog (Pdu-twist) to reveal mesodermal specification within this lineage. We show that Pdu-twist mRNA is already maternally distributed. After fertilization, ooplasmatic segregation leads to relocation of Pdu-twist transcripts into the somatoblast (2d) lineage and 4d, indicating that the maternal component of Pdu-twist might be an important prerequisite for further mesoderm specification but does not represent a defining characteristic of the mesentoblast. However, after the primordial germ cells have separated from the 4d lineage, zygotic transcription of Pdu-twist is exclusively observed in the myogenic progenitors, suggesting that mesodermal specification occurs after the 4d stage. Previous studies on spiral cleaving embryos revealed a spatio-temporal correlation between the 4d lineage and the activity of an embryonic organizer that is capable to induce the developmental fates of certain micromeres. This has raised the question if specification of the 4d lineage could be connected to the organizer activity. Therefore, we aimed to reveal the existence of such a proposed conserved organizer in Platynereis employing antibody staining against dpERK. In contrast to former observations in other spiralian embryos, activation of MAPK signaling during 2d and 4d formation cannot be detected which questions the existence of a conserved connection between organizer function and specification of the 4d lineage. However, our experiments unveil robust MAPK activation in the prospective nephroblasts as well as in the macromeres and some micromeres at the blastopore in gastrulating embryos. Inhibition of MAPK activation leads to larvae with a shortened body axis, defects in trunk muscle spreading and improper nervous system condensation, indicating a critical function for MAPK signaling for the reorganization of embryonic tissues during the gastrulation process

Veel boomkwekers schaffen driftarme spuitdoppen aan

In de boomkwekerij sector werkt Telen met toekomst samen met verschillende stakeholders aan acht Best Practices. Eén van die Best Practices is driftbeperking en het gebruik van effectieve spuittechnieken. Het gaat er daarbij vooral om telers te stimuleren driftarme spuitdoppen en nieuwe emissie-arme technieken in te zetten

Goede hygiëne bij tomaat : voorkom verspreiding van ziekteverwekkers

verspreiden van de belangrijkste ziekteverwekkers (pathogenen) van tomaat tegen gaan. Denk aan: pepinomozaïekvirus (PepMV), Verticillium spp. en Clavibacter michiganensis subsp. michiganensis. Het is belangrijk dat u een goed plan van aanpak opstelt en de juiste maatregelen uitvoert om problemen te voorkomen

Goed klimaat tegen Japanse roest : juiste klimaatregeling in chrysant geeft beste bestrijding

Japanse roest (Puccinia horiana) is een constant loerend gevaar op ieder chrysantenbedrijf. Vaak wordt de schimmel preventief chemisch bestreden. Maar als uw klimaatregeling niet goed is, dan helpt dit onvoldoende. Er zullen toch sporen tot kieming komen. Daarom moet voor de bestrijding van Japanse roest alles gericht zijn op een goede klimaatstrategi

Cybraries in paradise: new technologies and ethnographic repositories.

Digital technologies are altering research practices surrounding creation and use of ethnographic field recordings, and the methodologies and paradigms of the disciplines centered around their interpretation. In this chapter we discuss some examples of our current research practices as fieldworkers in active engagement with cultural heritage communities documenting music and language in the Asia- Pacific region, and as developers and curators of the digital repository PARADISEC (the Pacific and Regional Archive for Digital Sources in Endangered Cultures: ). We suggest a number of benefits that the use of digital technologies can bring to the recording of material from small and endangered cultures, and to its re-use by communities and researchers. We believe it is a matter of social justice as well as scientific interest that ethnographic recordings held in higher education institutions should be preserved and made accessible to future generations. We argue that, with appropriate planning and care by researchers, digitization of research recordings in audiovisual media can facilitate access by remote communities to records of their cultural heritage held in higher education institutions to a far greater extent than was possible in the analog age.Australian Research Counci

Absence of evidence is not evidence of absence:On the limited use of regression discontinuity analysis in higher education

When higher education students are assessed multiple times, teachers need to consider how these assessments can be combined into a single pass or fail decision. A common question that arises is whether students should be allowed to take a resit. Previous research has found little to no clear learning benefits of resits and therefore suggested they might not be advantangeous as they are costly for both students and institutions. However, we conducted a simulation study that shows such a conclusion to be presumptuous. Absence of evidence is not evidence of absence; our results illustrate that if a resit effect were to exist, the analysis used in these studies (i.e. regression discontinuity analysis; RDA) lacked the power to detect such an effect. Power of RDA was only sufficient under extremely implausible conditions (i.e. large sample, large effect size, high correlation between examinations). To adequately compare the effect of assessment policies, researchers are recommended to use other methods than RDA

Software sensors as a tool for optimization of animal-cell cultures

In this thesis software sensors are introduced that predict the biomass activity and the concentrations of glucose, glutamine, lactic acid, and ammonium on line, The software sensors for biomass activity, glucose and lactic acid can be applied for any type of animal cell that is grown in a bioreactor system. The glutamine and ammonium software sensors are determined experimentally by correlating them to the acid-production rate. Therefore, they can only be used for Vero cells.In the development of these software sensors, much attention is paid to the verification of their basic elements, i.e. the oxygen uptake rate (OUR) and the acid production rate (APR). For the estimation of the OUR, information about the course of the oxygen solubility and the oxygen transfer coefficient during cultivation is considered very important, since fluctuations in one of these parameters will introduce a systematic error in the OUR. Experiments have shown that the oxygen solubility remains approximately constant throughout the cultivation, However, the oxygen transfer coefficient can vary significantly during cultivation. Because of this, a method for on-line determination of the oxygen transfer coefficient is developed. Application of this method results in an estimation of the OUR that is more reliable and contains less noise than the determination of the OUR using an off-gas mass spectrometer.The lactic-acid production rate (LPR) is estimated from the APR, which in turn is determined from the amount of base utilized to control the pH at a fixed level. The estimated LPR provides reliable results, until nutrient limitation occurs. After that, the predicted LPR is higher than the measured LPR. Since at the end of the cultivation the lactic-acid concentration starts to drop, the cells are likely to take up lactic acid as an energy source. This uptake is supposed to be at least partially responsible for the discrepancy between estimated and measured LPR. However, since the estimation of the LPR is accurate up to the moment that nutrient limitation occurs and since the aim of control is to prevent nutrient limitation, the estimated LPR can still be used for control purposes.After evaluation of the two basic elements of the software sensors, the sensors themselves are tested. Two software sensors use both the OUR and the LPR. These sensors, the glucose sensor and the biomass activity sensor, defined as the total energy requirement of the cultivated cells, both provide reliable signals. It is shown that the maximum error in the biomass activity signal, caused by the error in the LPR, is 4.6%. This error is small enough to be neglected. Also the estimation of the glucose concentration is accurate throughout the culture. The overall error in the estimation of the glucose uptake rate is found to be 6%.The software sensors for lactic acid, glutamine and ammonium are solely based on the APR. Since the APR only provides reliable values until nutrient limitation occurs, these software sensors can only be used up to that point too. However, in the range at which the software sensors are valid, they are accurate.Applying the software sensors, the effect of controlled addition of glucose and glutamine is studied. For hybridoma cells a significant reduction of the lacticacid production rate is described in literature when the glucose concentration is controlled at a fixed low level. Contradictory to this, the specific lactic-acid production rate for Vero cells is found not to change when glucose is controlled at different levels from 10 down to 0.25 mol.m -3. In fact, no significant changes in the cultivation conditions are observed at all. Reducing the glutamine concentration from 4 down to 0.5 mol.m -3yields in a significant reduction (38%) of the specific ammonium production rate. This reduction is corrected for the ammonium that is formed during the spontaneous decomposition of glutamine. Lowering the glutamine concentration in the culture also results in a reduced decomposition of glutamine. The total reduction in ammonium formation caused by these two effects is 62%. Although a significant reduction of the ammonium formation is achieved, no effect is observed on the growth rate and the maximum cell density of Vero cells.Analysis of the cultivation medium using off-line HPLC has shown that after approximately 100 hours of cultivation, two amino acids are depleted. To find out whether or not these amino acids, methionine and serine, are responsible for the limitations in growth rate and cell density, they are added sequentially at the end of a culture. At that point the biomass activity is already dropping. Adding first methionine results in a stabilization of the biomass activity, whereas first addition of serine does not seem to have any effect. Further addition of the second amino acid instantaneously results in an increase of the biomass activity, the growth rate and the cell density in both cases. This indicates that even serine, which is a nonessential amino acid, is essential to maintain cell growth. At the moment serine is depleted, the cells have to make serine themselves, which causes the growth rate to drop. When methionine, an essential amino acid, is depleted the cell growth stops completely.In an attempt to increase the maximum cell density, additional amounts of both amino acids are added to the cultivation medium prior to the start of the culture. Unexpectedly, serine again is depleted after 100 hours of cultivation, in spite of an initial serine concentration of 0.4 instead of 0.1 mol-m -3. The biomass activity drops instantaneously at the moment serine is depleted. After the serine concentration in the cultivation medium is restored, the biomass activity only partially recovers. Despite the short serine limitation, the cell density doubles compared to the reference culture that is executed without glucose and glutamine control and without supplementing limiting amino acids.If this kind of control systems are to be implemented into production systems, some kind of plant automation is required. This can vary from computer-controlled measurement- and control systems up to fully automized manufacturing execution systems (MES) that control all parts of the production process. These processes can vary from stock management and generation of reports, to manmachine interfaces that operate the measurement- and control systems. An MES becomes important when the production facility has to produce according to governmental regulations such as current good manufacturing practice (cGMP). The system ensures that all parts of the production process are executed according to these rules. Additional features are process- dependent control, the use of software sensors and predictive models, the use of historical data and on-line statistical techniques for trend analysis and detection of instrumentation failures