65Zinc uptake from blood into brain and other tissues in the rat

Zinc is essential for normal growth, development and brain function although little is known about brain zinc homeostasis. Therefore, in this investigation we have studied⁶⁵Zn uptake from blood into brain and other tissues and have measured the blood-brain barrier permeability to⁶⁵Zn in the anaesthetized rat in vivo. Adult male Wistar within the weight range 500–600 g were used.⁶⁵ZnCl₂ and [¹²⁵I]albumin, the latter serving as a vascular marker, were injected in a bolus of normal saline I.V. Sequential arterial blood samples were taken during experiments that lasted between 5 min and 5 hr. At termination, samples from the liver, spleen, pancreas, lung, heart, muscle, kidney, bone, testis, ileum, blood cells, csf, and whole brain were taken and analysed for radio-isotope activity. Data have been analysed by Graphical Analysis which suggests⁶⁵Zn uptake from blood by all tissues sampled was unidirectional during this experimental period except brain, where at circulation times<30 min,⁶⁵Zn fluxes were bidirectional. In addition to the blood space, the brain appears to contain a rapidly exchanging compartment(s) for⁶⁵Zn of about 4 ml/100g which is not csf.     

Blood-brain exchange routes and distribution of65Zn in rat brain

Zinc is essential for normal development and function of the CNS although much is to be learned about brain Zn homeostasis. In these experiments adult male Wistar rats within the weight range 500–600 g were used. Ventriculo-cisternal perfusion was performed to allow the measurement of⁶⁵Zn fluxes between blood and csf across the choroid plexuses. Blood-brain or blood-cerebrospinal fluid barrier permeability to⁶⁵Zn has been determined by graphical analysis in experiments that lasted between 5 and 180 minutes. Cerebral capillary permeability to⁶⁵Zn was found to be low with a K_in of about 5×10^–4ml/min/g. Choroid plexus permeability to⁶⁵Zn was about 12 fold greater, although Zn influx to brain via this route was <5% that across cerebral capillaries. The autoradiographic distribution of⁶⁵Zn in brain showed regional variation with lowest levels in white matter and high levels in the dentate gyrus and hippocampus.     

Uptake and Distribution of Iron and Transferrin in the Adult Rat Brain

Brain uptake of iron-59 and iodine-125-labelled transferrin from blood in the adult rat has been investigated using graphical analysis to determine the blood-brain barrier permeability to these tracers in experiments that lasted between 5 min and 8 days. The blood-brain barrier permeability (K(in)) to 59Fe was 89 x 10(-5) ml/min/g compared to the value of 7 x 10(-5) ml/min/g for 125I-transferrin, which is similar to that of albumin, a plasma marker. The autoradiographic distribution of these tracers in brain was also studied to determine any regional variation in brain uptake after the tracers had been administered either systemically or applied in vitro. No regional uptake was seen for 125I-transferrin even after 24 h of circulation. In contrast, 59Fe showed selective regional uptake by the choroid plexus and extra-blood-brain barrier structures 4 h after administration. After 24 h of circulation, 59Fe distribution in brain was similar to the transferrin receptor distribution, as determined in vitro, but was unlike the distribution of nonhaem iron determined histochemically. The data suggest that brain iron uptake does not involve any significant transcytotic pathway of transferrin-bound iron into brain. It is proposed that the uptake of iron into brain involves the entry of iron-loaded transferrin to the cerebral capillaries, deposition of iron within the endothelial cells, followed by recycling of apotransferrin to the circulation. The deposited iron is then delivered to brain-derived transferrin for extracellular transport within the brain, and subsequently taken up via transferrin receptors on neurones and glia for usage or storage.     

Restoration of an Ecosystem Function to Revegetation Communities: The Role of Invertebrate Macropores in Enhancing Soil Water Infiltration

Guidelines for revegetation in agricultural landscapes may not address restoration of ecosystem functions because management is focused on the replanting stage, although certain functions are delivered by organisms that colonize revegetation months or years later. We investigated the ecosystem function of water infiltration to tree root zones and channels, delivered by invertebrates that form soil macropores. We measured macropore density and infiltration rates at revegetation sites established on retired grazing land, in relation to site age, tree species composition, and geographical location, compared with adjacent matched pastures. Revegetated sites had significantly more macropores than pastures, and revegetation sites aged 11–20 years had more macropores than sites aged 3–5 and 6–10 years. Tree species had a marginal effect, with more macropores in sites with Acacia spp. and Eucalyptus spp. than those with Eucalyptus spp. only. Besides ants, the main groups of soil burrowers were mygalomorph and lycosid spiders and also ground‐nesting native bees. Infiltration rates in revegetation sites aged 11–20 years were double those of pastures and of 3–5 and 6–10 year sites. This is the first study to quantify the rate of recovery of an invertebrate‐driven soil hydrological ecosystem function following revegetation.     

Design and testing for a nontagged F1-V fusion protein as vaccine antigen against bubonic and pneumonic plague

A two-component recombinant fusion protein antigen was re-engineered and tested as a medical counter measure against the possible biological threat of aerosolized Yersinia pestis. The active component of the proposed subunit vaccine combines the F1 capsular protein and V virulence antigen of Y. pestis and improves upon the design of an earlier histidine-tagged fusion protein. In the current study, different production strains were screened for suitable expression and a purification process was optimized to isolate an F1-V fusion protein absent extraneous coding sequences. Soluble F1-V protein was isolated to 99% purity by sequential liquid chromatography including capture and refolding of urea-denatured protein via anion exchange, followed by hydrophobic interaction, concentration, and then transfer into buffered saline for direct use after frozen storage. Protein identity and primary structure were verified by mass spectrometry and Edman sequencing, confirming a purified product of 477 amino acids and removal of the N-terminal methionine. Purity, quality, and higher-order structure were compared between lots using RP-HPLC, intrinsic fluorescence, CD spectroscopy, and multi-angle light scattering spectroscopy, all of which indicated a consistent and properly folded product. As formulated with aluminum hydroxide adjuvant and administered in a single subcutaneous dose, this new F1-V protein also protected mice from wild-type and non-encapsulated Y. pestis challenge strains, modeling prophylaxis against pneumonic and bubonic plague. These findings confirm that the fusion protein architecture provides superior protection over the former licensed product, establish a foundation from which to create a robust production process, and set forth assays for the development of F1-V as the active pharmaceutical ingredient of the next plague vaccine.     

Grassland area determines beetle assemblage dissimilarity from surrounding floodplain forest

Patch size is known to affect biodiversity in fragmented landscapes, but is usually examined in systems where the surrounding matrix habitat is unfavourable. We examined beetle diversity in a floodplain ecosystem that is characterised by naturally occurring grassland patches within a dominant matrix of contrasting yet habitable forest. We asked whether differences in the beetle assemblage between grassland and forest vegetation depended on the area of the grassland patch, which is a function of its flooding frequency and duration: smaller grasslands tend to be higher on the floodplain and are flooded less often and for shorter periods than larger grasslands. We found a negative relationship between grassland area and beetle abundance and species richness, and a positive relationship between grassland area and compositional dissimilarity from the surrounding forest. As expected, we found an overall difference in composition between forest and grassland assemblages, with five beetle species more common in the grasslands. Our study indicates that floodplain grasslands not only support beetle assemblages that are distinct from the surrounding forest, but that assemblages from the larger grasslands are compositionally more distinct than those from smaller grasslands. A likely cause of this pattern is the reduced edge effects and greater environmental contrast between forest and large grasslands that may be exposed to greater variation in local climate. Ongoing changes to flood regimes and potential encroachment of forest plants may decrease grassland area in the future, which may reduce spatial heterogeneity in the insect community in this unique floodplain ecosystem.     

Risk factors of peripheral arterial disease: a case control study in Sri Lanka

Background

Peripheral artery disease (PAD) is an important global health problem and contributes to notable proportion of morbidity and mortality. This particular manifestation of systemic atherosclerosis is largely under diagnosed and undertreated. For sustainable preventive strategies in a country, it is mandatory to identify country-specific risk factors. We intended to assess the risk factors of PAD among adults aged 40–74 years.

Methods

This case control study was conducted in 2012–2013 in Sri Lanka. Seventy-nine cases and 158 controls in the age group of 40–74 years were selected for the study in order to have case to control ratio 1:2. The criterion for selecting cases and control was based on Ankle brachial pressure index (ABPI). Cases were selected from those who had ABPI 0.85 or less (ABPI ≤0.85) in either lower limb. Controls were selected from those ABPI score between 1.18 and 1.28 in both lower limbs. Only newly identified individuals with PAD were selected as cases. Controls were selected from the same geographical location and within the 5 year age group as cases.

Results

The history of diabetes mellitus more than 10 years (OR 5.8, 95% CI 2.2–14.2), history of dyslipidemia for more than 10 years (OR 4.9, 95% CI 2.1–16.2), history of hypertension for more than 10 years (OR 3.8, 95% CI 1.8–12.7) and smoking (OR 2.9, 95% CI 1.2–6.9), elevated HsCRP (OR 3.7, 95% CI 1.2–12.0) and hyperhomocysteinemia (OR 3.0, 95% CI 1.1–8.1) were revealed as country specific significant risk factor of PAD.

Conclusions

Diabetes mellitus, hypertension, dyslipidemia, smoking as well as elevated homocysteine and HsCRP found as risk factors of PAD. Longer the duration or higher level exposure to these risk factors has increased the risk of PAD. These findings emphasis the need for routine screening of PAD among patients with the identified risk factors.

     

The role of fish-poultry integration on fish growth performance,yields and economic benefits among smallholder farmers in sub-Saharan Africa,Tanzania

Aquaculture practices from sub-Saharan Africa are characterised by low production, owing to improper technology. Production can be increased through integrating fish farming with other existing on-farm activities, particularly livestock husbandry. We assessed the role of fish-poultry integration on all male Nile tilapia, Oreochromis niloticus growth performance, yields and economic benefits among smallholder farmers in sub-Saharan Africa, Tanzania. The study also compared phytoplankton species composition, abundance and biomass between the fish-poultry integration and non-integrated system. After 180 days of the experiment, all male O. niloticus cultured under fish-poultry integration exhibited significantly higher growth rates than those in the non-integrated system (p < 0.05). Gross fish yield (GFY), net fish yield (NFY) and net annual yields (NAY) obtained from fish-poultry integration were significantly higher than those from non-integrated system (p < 0.05). Partial enterprise budget analysis revealed that fish-poultry integration was more profitable than the non-integrated system. Moreover, fish-poultry integrated system produced significantly higher phytoplankton abundance and biomass than those from the non-integrated system. Results demonstrate that rural smallholder farmers can achieve higher growth rate, farm net yields and income by integrating all male O. niloticus with other on-farm activities than practising a stand-alone fish culture system.