Extrinsic primary afferent signalling in the gut

Visceral sensory neurons activate reflex pathways that control gut function and also give rise to important sensations, such as fullness, bloating, nausea, discomfort, urgency and pain. Sensory neurons are organised into three distinct anatomical pathways to the central nervous system (vagal, thoracolumbar and lumbosacral). Although remarkable progress has been made in characterizing the roles of many ion channels, receptors and second messengers in visceral sensory neurons, the basic aim of understanding how many classes there are, and how they differ, has proven difficult to achieve. We suggest that just five structurally distinct types of sensory endings are present in the gut wall that account for essentially all of the primary afferent neurons in the three pathways. Each of these five major structural types of endings seems to show distinctive combinations of physiological responses. These types are: 'intraganglionic laminar' endings in myenteric ganglia; 'mucosal' endings located in the subepithelial layer; 'muscular–mucosal' afferents, with mechanosensitive endings close to the muscularis mucosae; 'intramuscular' endings, with endings within the smooth muscle layers; and 'vascular' afferents, with sensitive endings primarily on blood vessels. 'Silent' afferents might be a subset of inexcitable 'vascular' afferents, which can be switched on by inflammatory mediators. Extrinsic sensory neurons comprise an attractive focus for targeted therapeutic intervention in a range of gastrointestinal disorders.Australian National Health and Medical Research Counci

Remote detection of invasive alien species

The spread of invasive alien species (IAS) is recognized as the most severe threat to biodiversity outside of climate change and anthropogenic habitat destruction. IAS negatively impact ecosystems, local economies, and residents. They are especially problematic because once established, they give rise to positive feedbacks, increasing the likelihood of further invasions and spread. The integration of remote sensing (RS) to the study of invasion, in addition to contributing to our understanding of invasion processes and impacts to biodiversity, has enabled managers to monitor invasions and predict the spread of IAS, thus supporting biodiversity conservation and management action. This chapter focuses on RS capabilities to detect and monitor invasive plant species across terrestrial, riparian, aquatic, and human-modified ecosystems. All of these environments have unique species assemblages and their own optimal methodology for effective detection and mapping, which we discuss in detail

A comparison of micromanometric and standard manometric techniques for recording of oesophageal motility

Perfused micromanometric assemblies with an outer diameter of 2 mm or less have been developed for use in premature infants and small laboratory animals. Such assemblies offer advantages with regard to subject comfort and low perfusion rates that make them attractive for use in adults. The aim of this study was to investigate the recording fidelity of micromanometric assemblies in the measurement of oesophageal peristalsis in adults. Two micromanometric assemblies with an outer diameter of 1.8-2.0 mm and a length suitable for use in adults (165 cm), and containing micromanometric lumina of 0.28-0.35 mm i.d. and a standard lumen of 0.6-0.75 mm i.d. were evaluated. Each assembly was tested by measurement of pressure rise rate in response to sudden occlusion, and in vivo during oesophageal peristalsis by simultaneous comparison with an intraluminal strain gauge. At perfusion rates of 0.01-0.15 mL min-1 microlumina achieved pressure rise rates of 21-430 mmHg sec-1 that were comparable to 37-390 mmHg sec-1 for the standard lumina perfused at 0.15-0.6 mL min-1. During oesophageal peristalsis, micromanometric lumina recorded the occurrence and timing of all pressure waves accurately when compared with standard lumina and the microtransducer. However, microlumina under-recorded pressure wave amplitude to varying degrees dependent upon perfusion rate although the performance of microlumina could be improved to that of the standard lumen by shortening their length to 70 cm. Micromanometric assemblies are suitable for recording oesophageal peristalsis in adults although there is some impairment of absolute manometric fidelity. Fidelity can be improved by minimizing total assembly length