Nieuwe inzichten in de interactie tussen sorghum en het parasitaire onkruid Striga hermontica

Striga hermonthica (Del.) Benth. is een parasitaire plant uit de Orobanchaceae familie. De soort komt van oorsprong voor in Afrika en hecht zich aan de wortels van belangrijke voedselgewassen als maïs, sorghum, gierst en rijst. In grote delen van Afrika heeft Striga zich ontwikkeld tot de belangrijkste groeireducerende factor. Veelvuldig is waargenomen dat de problemen met Striga toenemen wanneer de bodemvruchbaarheid afneem

The 'Adat' institutionand the Management of Grand Forest 'Herman Yohannes' in Indonesian Timor: The Role of Design Principles for Sustainable Management of Common Pool Resources

__Abstract__ Local success stories of sustainable forest management can inspire scientists and decision-makers. This article analyses the traditional ‘Adat’ institution that plays a role in the management of Grand Forest Park ‘Herman Yohannes’, in the Western part of Timor where the Adat forest management regulation has been formally restored. The original set of design principles for sustainable management of common pool resources of Elinor Ostrom (1990) has been used in this study as an analytical framework for understanding the role of the Adat institution in respect to the forest. In the park, the local community applies Adat for protection and management of the forest that has been its home for centuries. It appears that Ostrom’s design principles can be identified in the current Adat institution and play a role in the sustainable management of the forest. Although many other variables can lead to success or failure of institutions, the original (internal) design principles are still valuable as a practical tool for building institutions that are – under certain conditions – able to sustain common pool resources. The findings confirm the importance of traditional institutions in successful forest management. The study recommends that decision-makers take into account existing traditional management systems that have shown long term functionality

Diagnostic reference frames for seizures: a validation study

Introduction We developed structured descriptions of signs and symptoms for specific seizure types (called Diagnostic Reference Frames—DRFs—by us) that can serve as a frame of reference in the process of classifying patients with epileptic seizures. In this study the validity of the DRFs for clinical use is evaluated and described. Material and methods In this study we use a decision support system based on the DRFs and using Bayes's rule for the validation of the DRFs. Patient's manifestations are entered in the decision support system and by successively applying Bayes's rule posterior probabilities are calculated. The DRFs with the highest posterior probability gives an indication of the classification of the seizure. The validation of the DRFs was performed by comparing the seizure type with the highest posterior probability with the classification of experienced epileptologists on a series of test cases with known epileptic seizures. In this way we assessed the accuracy of the DRFs in classifying patients with epileptic seizures. Results We included sixty–six patients in this efficacy study. The patients and/or their relatives described the manifestations occurring during a seizure. Sixty cases (91%) were correctly classified using the decision support system. Discussion The accuracy of 91 % indicates that the knowledge encoded in the DRFs for the included seizure types is valid. The next step is to test the DRFs in a clinical setting to evaluate the applicability in daily practice

Adaptive intrapatient dose escalation of cisplatin in combination with low-dose vp16 in patients with nonsmall cell lung cancer

The objective of this phase II and pharmacologic study was to explore the feasibility toxicity and activity of adaptive intrapatient dose escalation of cisplatin in a dose-intensive weekly schedule using predefined levels of exposure, with the ultimate aim to improve the antitumour activity of the therapy in patients with nonsmall cell lung cancer (NSCLC). Platinum DNA-adduct levels in peripheral white blood cells during treatment were used as the primary parameter for adaptive dosing. If DNA-adduct levels were not available, the area under the concentration-time curve (AUC) of unbound platinum in plasma was used for dose adaptation. Target levels for DNA-adducts and AUC have been defined in a previously performed pharmacologic study. The feasibility of adaptive dosing was tested in 76 patients with stage IIIB and IV NSCLC, who were planned to receive 6 weekly courses of cisplatin at a starting dose of 70 mg m-2, together with daily low oral dose of 50 mg VP16. In total, 37 patients (49%) who were given more than one course received a dose increase varying from 10 to 55%. The majority of patients reached the defined target levels by a dose increase during course two. Relevant grade 2 neurotoxicity was observed in eight (10%) patients and reversible ototoxicity grade 2 in 14 (18%) patients. The strategy of adaptive intrapatient dose adjustment of cisplatin is practically feasible in a research setting even when results for dose adaptation have to be reported within a short time-period of I week. The toxicity appeared to be manageable in this cohort of patients. In some patients, exposure after the standard dose was substantially lower than the defined target level and significant dose escalations of more than 50% had to be applied. The response rate (RR) was relatively high: overall 40% (29 out of 72 patients) partial remission (PR), in patients with stage IIIB the RR was 60% (15 out of 25 patients) and with stage IV 30% (14 out of 47 patients). Randomised studies are needed to determine whether the adaptive dosing strategy results in better efficacy than standard dosing

Aspecten van bedrijfshygiene in de pootaardappelteelt

Na de inleiding volgt in hoofdstuk 2 van deze publikatie een overzicht van de ziekten die onze pootaardappelteelt bedreigen, de wijze van besmetting met deze ziekten en de mogelijkheden van voorkomen of bestrijden. In hoofdstuk 3 worden de economische aspecten van het al dan niet in voldoende mate toepassen van bedrijfshygiene in de pootaardappelteelt zoveel mogelijk gekwantificeerd. In hoofdstuk 4 wordt tenslotte een aantal bedrijfshygienische maatregelen besproken, die voor de individuele producent en collecteur in aanmerking komen om te worden getroffe

Vertraging van het tijdstip van Striga hermonthica-aanhechting: Een optie voor opbrengstverhoging van sorghum?

In de semi-aride tropen van Afrika vormt het parasitaire onkruid Striga-hermonthica een ware plaag bij de teelt van sorghum. In onderzoek is het dynamisch karakter van de waard-parasiet interactie centraal gesteld. Hieruit komt het belang van het aanhechtingstijdstip van de parasiet aan de wortels van de waardplant naar voren: hoe ouder de gewasplant bij eerste aanhechting, des te kleiner de schade. Perspectieven van deze waarneming voor de beheersing van Striga worden besproke

No Time-Dependent Effects of Psychosocial Stress on Fear Contextualization and Generalization:A Randomized-Controlled Study With Healthy Participants

The formation of context-dependent fear memories (fear contextualization) can aid the recognition of danger in new, similar, situations. Overgeneralization of fear is often seen as hallmark of anxiety and trauma-related disorders. In this randomized-controlled study, we investigated whether exposure to a psychosocial stressor influences retention of fear contextualization and generalization in a time-dependent manner. The Trier Social Stress Test was used to induce psychosocial stress. Healthy male participants (n = 117) were randomly divided into three experimental groups that were subjected to the acquisition phase of the Fear Generalization Task: (1) without stress, (2) immediately after acute stress, or (3) 2 h after acute stress. In this task, a male with neutral facial expression (conditioned stimuli) was depicted in two different contexts that modulated the conditioned stimuli–unconditioned stimuli (=shock) association (threat, safe). Salivary alpha-amylase and cortisol levels were measured throughout the experiment. After a 24-h delay, context-dependency of fear memory was investigated with an unannounced memory test consisting of the threat and safe contexts alternated with a novel context (the generalization context). Multilevel analyses revealed that participants showed increased fear-potentiated startle responses to the conditioned stimuli in the threat compared to the safe context, at the end of the acquisition phase, indicating adequate fear contextualization. Directly after acquisition, there were no time-dependent effects of psychosocial stress on fear contextualization. Context-dependency of fear memories was retained 24 h later, as fear-potentiated startle responding was modulated by context (threat > safe or novel). At that time, the context-dependency of fear memories was also not influenced by the early or late effects of the endogenous stress response during acquisition. These results with experimental stress deviate in some aspects from those earlier obtained with exogenous hydrocortisone administration, suggesting a distinct role for stress mediators other than cortisol

Time-dependent effects of psychosocial stress on the contextualization of neutral memories

Memories about stressful experiences need to be both specific and generalizable to adequately guide future behavior. Memory strength is influenced by emotional significance, and contextualization (i.e., encoding experiences with their contextual details) enables selective context-dependent retrieval and protects against overgeneralization. The current randomized-controlled study investigated how the early and late phase of the endogenous stress response affects the contextualization of neutral and negative information. One hundred healthy male participants were randomly divided into three experimental groups that performed encoding either 1) without stress (control), 2) immediately after acute stress (early) or 3) two hours after acute stress (late). Stress was induced via the Trier Social Stress Test and salivary alpha-amylase and cortisol levels were measured throughout the experiment. In the Memory Contextualization Task, neutral and angry faces (items) were depicted against unique context pictures during encoding. During testing 24 h later, context-dependent recognition memory of the items was assessed by presenting these in either congruent or incongruent contexts (relative to encoding). Multilevel analyses revealed that neutral information was more contextualized when encoding took place two hours after psychosocial stress, than immediately after the stressor. Results suggest that the late effects in the unique, time-dependent sequence of a healthy endogenous stress response, could complement reduced contextualization immediately after stress. The contextualization of negative information was not influenced by psychosocial stress, as opposed to earlier reported effects of exogenous hydrocortisone administration. An imbalance between the early and late effects of the endogenous stress response could increase vulnerability for stress-related psychopathology.</p