Positioning of Subject and of Nasogastric Tube during a Gastric Secretion Study

The histamine-infusion test was conducted in 50 subjects with a modification that allowed the completeness of recovery of the maximal gastric secretion to be assessed. The effects of the exact position of the tube and the position of the subject on the completeness of recovery were investigated. A simple water-recovery test was found to be as reliable as fluoroscopy for showing that the tip of the tube was within the stomach. Provided that the tip was within the stomach, the exact position of the tube did not affect recovery. Furthermore, recovery in 19 subjects was not appreciably affected by changing the person from the left lateral to the supine semirecumbent position.     

Measurement of Leaf Water Potential Using the J14 Press

The diurnal variation in leaf water potential of wheat underfield conditions is determined by means of the Scholander pressurechamber and the J14 press. Experimental work was carried outon several days during both the vegetative and reproductivegrowth stages. An exponential relationship (v = 4.09 e^0.05x),with coefficient of determination r² = 0.81, is found to existbetween the J14 press and Scholander pressure chamber measurements.Both the Scholander pressure chamber and J14 press appear capableof following hourly variations in leaf water potential provided8 and 16 leaves per sample are used for the two instrumentsrespectively.     

Surface Potential Measurement of Bacteria Using Kelvin Probe Force Microscopy

Surface potential is a commonly overlooked physical characteristic that plays a dominant role in the adhesion of microorganisms to substrate surfaces. Kelvin probe force microscopy (KPFM) is a module of atomic force microscopy (AFM) that measures the contact potential difference between surfaces at the nano-scale. The combination of KPFM with AFM allows for the simultaneous generation of surface potential and topographical maps of biological samples such as bacterial cells. Here, we employ KPFM to examine the effects of surface potential on microbial adhesion to medically relevant surfaces such as stainless steel and gold. Surface potential maps revealed differences in surface potential for microbial membranes on different material substrates. A step-height graph was generated to show the difference in surface potential at a boundary area between the substrate surface and microorganisms. Changes in cellular membrane surface potential have been linked with changes in cellular metabolism and motility. Therefore, KPFM represents a powerful tool that can be utilized to examine the changes of microbial membrane surface potential upon adhesion to various substrate surfaces. In this study, we demonstrate the procedure to characterize the surface potential of individual methicillin-resistant Staphylococcus aureus USA100 cells on stainless steel and gold using KPFM.     

Potential Importance of Inhalation Exposures for Wildlife Using Screening-Level Ecological Risk Assessment

Ecological risk assessments (ERAs) have largely ignored exposure to wildlife via inhalation on the assumption that it is negligible compared to the ingestion route of exposure. The assessment of inhalation risk also has been limited due to a paucity of relevant ecotoxicity data. This article presents toxicity reference values (TRVs) for small mammals based on chronic or subchronic exposure studies for a range of organic and trace metal contaminants and ecologically relevant inhalation endpoints. Potential risk to small mammals due to ingestion and inhalation exposure were compared in two hypothetical air emission scenarios for a point source (incinerator) and non-point source emissions (vehicular emissions). Using two screening-level ERAs, we conclude that it may now be time to reconsider inhalation risk to wildlife in the case of atmospheric emissions of some metals and volatile organic compounds (VOCs). In the case of birds, the toxicological database remains too small to assess risks via this pathway. However, for mammals, we suggest that inhalation exposures to contaminants such as cadmium, benzene, and other VOCs could be important.     

Comparative Evaluation of Water Recovery Test and Fluoroscopic Screening in Positioning a Nasogastric Tube during Gastric Secretory Studies

Acid secretion studies were carried out in 50 patients. Fluoroscopy or a modified water recovery test was used to position the nasogastric tube. For every patient each positioning procedure was used on one of two consecutive days, and acid output studies were performed. The tests were assessed by two observers and accepted or rejected. Analysis revealed no significant differences between the acid studies irrespective of the method used for positioning the nasogastric tube. Rejection rates by either procedure showed no significant difference. Practical considerations favour the continued use of water recovery as a means of positioning the nasogastric tube for gastric secretion studies.     

Measurement of Stem Water Potential of Young Plants Using a Hygrometer Attached to the Stem

A simple method was developed for the continuous non-destructivemeasurement of plant stem water potential. It consists of exposinga small section of stem vascular tissue and attaching to ita standard commercially available dewpoint hygrometer. Excellentagreement was found between water potential determined by thismethod, and that measured with a pressure-chamber on leavescovered with aluminium foil. Stem water potentials respondedwithin minutes to changes in radiation and transpiration. Resistanceto water uptake was found to be independent of the rate of transpiration.     

Mapping the Potential Risk of Mycetoma Infection in Sudan and South Sudan Using Ecological Niche Modeling

In 2013, the World Health Organization (WHO) recognized mycetoma as one of the neglected tropical conditions due to the efforts of the mycetoma consortium. This same consortium formulated knowledge gaps that require further research. One of these gaps was that very few data are available on the epidemiology and transmission cycle of the causative agents. Previous work suggested a soil-borne or Acacia thorn-prick-mediated origin of mycetoma infections, but no studies have investigated effects of soil type and Acacia geographic distribution on mycetoma case distributions. Here, we map risk of mycetoma infection across Sudan and South Sudan using ecological niche modeling (ENM). For this study, records of mycetoma cases were obtained from the scientific literature and GIDEON; Acacia records were obtained from the Global Biodiversity Information Facility. We developed ENMs based on digital GIS data layers summarizing soil characteristics, land-surface temperature, and greenness indices to provide a rich picture of environmental variation across Sudan and South Sudan. ENMs were calibrated in known endemic districts and transferred countrywide; model results suggested that risk is greatest in an east-west belt across central Sudan. Visualizing ENMs in environmental dimensions, mycetoma occurs under diverse environmental conditions. We compared niches of mycetoma and Acacia trees, and could not reject the null hypothesis of niche similarity. This study revealed contributions of different environmental factors to mycetoma infection risk, identified suitable environments and regions for transmission, signaled a potential mycetoma-Acacia association, and provided steps towards a robust risk map for the disease.     

植物基因工程的应用与研究进展及潜在风险性分析

简要综述近年来植物基因工程在改善植物性状,提高植物抗性等遗传育种方面的应用与研究进展。重点介绍了植物基因工程的应用,如改良农产品品质,提高农作物抗病虫毒、抗除草剂、抗自然灾害的能力,开发疫苗等。分析了植物基因工程在农作物育种方面的应用前景及其潜在的风险性。