Integrated systems research for sustainable smallholder agriculture in the Central Mekong: Achievements and challenges of implementing integrated systems research

Internal Revie

Electrical modulation of the sympathetic nervous system in order to augment cerebral blood flow: a protocol for an experimental study

Introduction: Cerebral blood flow (CBF) is regulated by several mechanisms. Neurogenic control has been a matter of debate, even though several publications reported the effects of changes in sympathetic tone on CBF. Transcutaneous electrical nerve stimulation and spinal-cord stimulation have been shown to influence peripheral and cerebral blood flow through a sympathetic pathway. The authors hypothesise that certain pathological conditions result in a relative increase in the neurogenic regulation of CBF and that this regulation can be modulated electrically. Methods and analysis: Patients with cerebral vasospasm after subarachnoid haemorrhage will be included. The experimental set-up measures several parameters that are involved in cerebral blood flow regulation in patients with cerebral vasospasm after subarachnoid haemorrhage. Measurements are taken at baseline and with stimulation in several frequencies. An ad hoc statistical analysis is used to evaluate different settings of the electrical stimulation. Autoregulation is evaluated with transfer function analysis and autoregulatory index calculations. Ethics and dissemination: Ethical registration was granted by Medical Review Ethics Committee Groningen (ID METc 2010.123). All participants provide written informed consent on participation. Upon finishing a pilot study to investigate feasibility and effect, either future prospective (randomised) studies will be designed, or other modalities of electrical stimulation will be explored using the same set-up

Microscale spatial distributions of microbes and viruses in intertidal photosynthetic microbial mats

Intertidal photosynthetic microbial mats from the Wadden Sea island Schiermonnikoog were examined for microscale (millimetre) spatial distributions of viruses, prokaryotes and oxygenic photoautotrophs (filamentous cyanobacteria and benthic diatoms) at different times of the year. Abundances of viruses and prokaryotes were among the highest found in benthic systems (0.05–5.43 × 1010 viruses g−1 and 0.05–2.14 × 1010 prokaryotes g−1). The spatial distribution of viruses, prokaryotes and oxygenic photoautotrophs were highly heterogeneous at mm scales. The vertical distributions of both prokaryotic and viral abundances were related to the depth of the oxygenic photoautotrophic layer, implying that the photosynthetic mat fuelled the microbial processes in the underlying layer. Our data suggest that viruses could make an important component in these productive environments potentially affecting the biodiversity and nutrient cycling within the mat

The influence of transcutaneous electrical neurostimulation (TENS) on human cerebral blood flow velocities

It has been shown that transcutaneous electrical neurostimulation (TENS) reduces sympathetic tone. Spinal cord stimulation (SCS) has proven qualities to improve coronary, peripheral, and cerebral blood circulation. Therefore, we postulate that TENS and SCS affect the autonomic nervous system in analogous ways. In this line of thought, cervical application of TENS might be a useful and simple adjunct in the treatment of cerebrovascular disease by improving cerebral blood flow. Experiments were performed in order to assess whether cervical TENS is safe and whether an effect on cerebral blood flow velocity (CBFV) can be shown in healthy subjects. A controlled, non-randomized, phase 1 study was performed with 20 healthy volunteers. Cervical TENS was applied in several frequencies, with and without hyperventilation. Continuous registration of blood pressure, pulse, CBFV (estimated by transcranial Doppler sonography) and end-tidal carbon dioxide concentration was performed. Cervical TENS was well-tolerated by all subjects. Despite small effects on heart rate (HR) and mean arterial blood pressure (MAP), a significant effect on middle cerebral artery (MCA) blood flow velocity was not demonstrated. No effect of age, gender, current or session order on MCA, HR, or MAP was found. TENS did not influence the effect of hyperventilation. In these experiments, application of cervical TENS is proven to be a safe procedure. However, no effects on cerebral blood flow velocity could be detected, perhaps due to the intact cerebral autoregulation in the healthy volunteers

Reactive oxygen production induced by near-infrared radiation in three strains of the Chl d-containing cyanobacterium Acaryochloris marina

Cyanobacteria in the genus Acaryochloris have largely exchanged Chl a with Chl d, enabling them to harvest near-infrared radiation (NIR) for oxygenic photosynthesis, a biochemical pathway prone to generate reactive oxygen species (ROS). In this study, ROS production under different light conditions was quantified in three Acaryochloris strains (MBIC11017, HICR111A and the novel strain CRS) using a real-time ethylene detector in conjunction with addition of 2-keto-4-thiomethylbutyric acid, a substrate that is converted to ethylene when reacting with certain types of ROS. In all strains, NIR was found to generate less ROS than visible light (VIS). More ROS was generated if strains MBIC11017 and HICR111A were adapted to NIR and then exposed to VIS, while strain CRS demonstrated the opposite behavior. To our knowledge, this is the first study of ROS generation associated with NIR-driven oxygenic photosynthesis and it suggests that Acaryochloris can avoid a considerable amount of light-induced stress by using NIR instead of VIS for its photosynthesis, adding further evolutionary arguments to their widespread appearance

Reactive oxygen production induced by near-infrared radiation in three strains of the Chl <em>d</em><i>-</i>containing cyanobacterium <i>Acaryochloris marina</i>

Cyanobacteria in the genus Acaryochloris have largely exchanged Chl a with Chl d, enabling them to harvest near-infrared-radiation (NIR) for oxygenic photosynthesis, a biochemical pathway prone to generate reactive oxygen species (ROS). In this study, ROS production under different light conditions was quantified in three Acaryochloris strains (MBIC11017, HICR111A and the novel strain CRS) using a real-time ethylene detector in conjunction with addition of 2-keto-4-thiomethylbutyric acid, a substrate that is converted to ethylene when reacting with certain types of ROS. In all strains, NIR was found to generate less ROS than visible light (VIS). More ROS was generated if strains MBIC11017 and HICR111A were adapted to NIR and then exposed to VIS, while strain CRS demonstrated the opposite behavior. This is the very first study of ROS generation and suggests that Acaryochloris can avoid a considerable amount of light-induced stress by using NIR instead of VIS for its photosynthesis, adding further evolutionary arguments to their widespread appearance

Systems analysis in AIS: potentials and pitfalls

Agricultural innovation systems are complex, multi-layered, and can be difficult to define and analyse. In this paper, we provide examples of ‘systems analysis’: describing the context, what was done, and how the outcomes informed broader research and development activities. The five cases describe analyses of: i) agricultural systems in North-West Vietnam; ii) household food security in Central Vietnam; iii) agricultural innovation systems in Central Africa; iv) wheat commodity systems in Sub-Saharan Africa, and v) the national agricultural research system in Papua New Guinea. These cases show that while there is no single best method to conduct systems analysis within a broader AIS approach, ‘good’ systems analysis demonstrates several common characteristics. Suggestions for system analysis in practice include: clarifying objectives and expectations; balancing breadth and depth; paying attention to power dynamics; avoiding an assumption of predictability; careful mixing of quantitative and qualitative methods; and a keeping a focus on informing action

Clonal selection in xenografted human T cell acute lymphoblastic leukemia recapitulates gain of malignancy at relapse

Compared with T-ALL diagnosis samples, samples obtained at relapse or after xenograft into immunodeficient mice exhibit additional genomic lesions in oncogenes and/or tumor suppressor genes; these lesions contribute to leukemia-initiating activity