Pathology in tropical medicine

The pathology o f a parasitic disease is a major link between the investigating parasitologist and those concerned with its epidemiology, socioeconomic impact, clinical treatment and control. The epidemiologist requires information about the incidence and prevalence of major pathological lesions attributable to on infection, which in turn will determine the social and economic impact of the disease and thus its priority for control. For both diagnosis and treatment, the clinician requires an understanding of the pathological mechanisms, and the potential for new drugs or vaccine development largely depends on such understanding. Recent years have seen remarkable improvements in determining the nature of pathology associated with parasitic infections. and in understanding their causative mechanisms. With this issue, Parasitology Today begins a series of special reviews designed to bring together these insights into parasite pathology (see pages 271-282). In this introductory overview. Charles Mackenzie traces the origins and development of the science.     

Shaping the flavivirus replication complex: It is curvaceous!

Flavivirus replication is intimately involved with remodelled membrane organelles that are compartmentalised for different functions during their life cycle. Recent advances in lipid analyses and gene depletion have identified a number of host components that enable efficient virus replication in infected cells. Here, we describe the current understanding on the role and contribution of host lipids and membrane bending proteins to flavivirus replication, with a particular focus on the components that bend and shape the membrane bilayer to induce the flavivirus‐induced organelles characteristic of infection.     

Morphological changes in melanized and non-melanized Cryptococcus neoformans cells post exposure to sparsely and densely ionizing radiation demonstrate protective effect of melanin

There is a need for novel and effective prophylactic treatments and radioprotective materials to protect civilians and military personnel from ionizing radiation in contaminated environments. Melanin, a naturally occurring, ubiquitous pigment, has been shown to confer radioresistance, acting as a potential radioprotective agent. We have demonstrated that melanized Cryptococcus neoformans (CN) cells had improved survival post ionizing irradiation than non-melanized ones. The goal of this study was to identify morphological changes in melanized and non-melanized CN cells following irradiation with densely-ionizing deuterons and alpha particles relative to sparsely-ionizing gamma radiation. We observed significant differences between the melanized and non-melanized CN cellular ultrastructure following irradiation. Melanized CN cells were relatively resistant to mid and max-dose levels of alpha particles and deuterons irradiation. Following irradiation the capsule was stripped, but the cell wall was intact and structural integrity was maintained. At the maximum dose, cytoplasmic vacuolization, and mitochondrial swelling started to occur. In contrast, the non-melanized CN strain was sensitive to the mid-dose radiation. Non-melanized cells presented two morphologies: small condensed, and swollen, lacking structural integrity. This morphological investigation provides the first direct evidence of the radioprotective properties of melanin in CN cells subjected to high RBE and high LET ionizing radiation.     

Triazole and Imidazole Reversed Nucleosides of L-Idose and D-Glucose

Abstract

6-azido-6-deoxy-gluco-(galacto)pyranose and 5-azido-5-deoxy-glucofuranose derivatives were used to obtain reversed nucleoside analogues with either the 5-aminoimidazole-4-carboxamide or 5-amino-1,2,3-triazol-4-carboxamide groups attached, through the N-1 site, to the C-6′ (C-5′) site of the sugar. When deprotected some of these compounds cyclised spontaneously to form a bond between the exocylic nitrogen and the anomeric carbon of the sugar.     

Parid foraging choices in urban habitat and their consequences for fitness

Urban environments are habitat mosaics, often with an abundance of exotic flora, and represent complex problems for foraging arboreal birds. In this study, we used compositional analysis to assess how Blue Tits Cyanistes caeruleus and Great Tits Parus major use heterogeneous urban habitat, with the aim of establishing whether breeding birds were selective in the habitat they used when foraging and how they responded to non‐native trees and shrubs. We also assessed whether they showed foraging preferences for certain plant taxa, such as oak Quercus, that are important to their breeding performance in native woodland. Additionally, we used mixed models to assess the impact of these different habitat types on breeding success (expressed as mean nestling mass). Blue Tits foraged significantly more in native than non‐native deciduous trees during incubation and when feeding fledglings, and significantly more in deciduous than evergreen plants throughout the breeding season. Great Tits used deciduous trees more than expected by chance when feeding nestlings, and a positive relationship was found between the availability of deciduous trees and mean nestling mass. Overall, the breeding performance of both species was poor and highly variable. Positive relationships were found between mean nestling mass and the abundance of Quercus for Great Tits, but not for Blue Tits. Our study shows the importance of native vegetation in the complex habitat matrix found in urban environments. The capacity of some, but not all, species to locate and benefit from isolated patches of native trees suggests that species vary in their response to urbanization and this has implications for urban ecosystem function.