Woody plant diversity,composition and structure in relation to environmental variables and land-cover types in Lake Wanchi watershed,central highlands of Ethiopia

Knowledge of vegetation dynamics associated with human land-use change and environmental variables is crucial for sustainable watershed management. The objective of this study was to analyse woody plant diversity in response to the effects of anthropogenic disturbances, and topographic variables in different land-cover types. Woody plants ≥5 cm diameter at breast height (DBH) were recorded from 20-by-20 m plots, those <5 cm DBH were recorded from 10-by-10 m plots, and tree seedlings were recorded in 3-by-3 m plots. Nonmetric multidimensional scaling with Bray–Curtis distance was employed to analyse woody species composition. Woody species richness was analysed using generalised linear modelling. Tree diameter-class distributions were examined for population structure. The study identified 104 woody plants belonging to 52 families, where 74.5% were indigenous and 16.7% were endemic to Ethiopia. Asteraceae, Fabaceae and Rosaceae were the most species-rich families. There was evidence for the effect of anthropogenic disturbance and elevation on woody species composition. Wetlands contained the highest woody species richness, while woody species richness declined with increasing elevation and disturbance. Evidence of good regeneration was observed in wetlands. To sustain the ecological functions and services provided by the watershed, rehabilitation of the forest and shrub-cover should be a high priority for local management authorities.     

Identification of Potential Vectors and Alternative Plant Hosts for the Phytoplasma Associated with Napier Grass Stunt Disease in Ethiopia

Napier grass ( Pennisetum purpureum ), the most important forage crop in East Africa, has recently been affected by a devastating disease named Napier Grass Stunt (NGS). A phytoplasma of group 16SrI has been associated with NGS in Kenya and Uganda, whereas in Ethiopia, group 16SrIII was previously identified in NGS affected fields. However, no insect vectors or alternative hosts have been recorded for NGS in East Africa. During 2005, surveys were conducted at NGS-affected plantations of Debre-Zeit and Zwai field stations in Addis Ababa. Leaf samples were collected from weeds located in and surrounding the NGS-affected areas. Leafhopper species were also surveyed by vacuum sampling in a search for natural phytoplasma vectors. Total DNA was extracted from plants and insects, and used as a template in nested polymerase chain reaction (nPCR) with universal 16S rRNA phytoplasma primers. Restriction fragment length polymorphism (RFLP), sequencing of PCR products and phylogenetic analysis were conducted for a finer identification and characterization of the phytoplasma associated with NGS. A 16SrIII-A phytoplasma with 100% of identity in the 16S rRNA sequence with that of the previously identified one in Napier Grass (accession no. DQ305977 ) was identified from alfalfa, Medicago sativa (accession no. DQ305982 ), Cynodon dactylon (accession no. DQ3058983 ), Exitianus sp. ( DQ305980 ) and Leptodelphax dymas collected in Debre Zeit (accession no. DQ305979 ) and Zwai (accession no. DQ305978 ). These findings suggest that M. sativa and Cy. dactylon are alternative reservoirs, and Exitianus sp. and L. dymas , potential vectors of the 16SrIII-A phytoplasma, which may have epidemiological implications in spreading NGS in Ethiopia.     

Evaluation of the Performance Characteristics of Bilayer Tablets: Part II. Impact of Environmental Conditions on the Strength of Bilayer Tablets

Ambient air humidity and temperature are known to influence the mechanical strength of tablets. The objective of this work is to understand the influence of processing parameters and environmental conditions (humidity and temperature) on the strength of bilayer tablets. As part of this study, bilayer tablets were compressed with different layer ratios, dwell times, layer sequences, material properties (plastic and brittle), first and second layer forces, and lubricant concentrations. Compressed tablets were stored in stability chambers controlled at predetermined conditions (40C/45%RH, 40C/75%RH) for 1, 3, and 5 days. The axial strength of the stored tablets was measured and a statistical model was developed to determine the effects of the aforementioned factors on the strength of bilayer tablets. As part of this endeavor, a full 3 × 2⁴ factorial design was executed. Responses of the experiments were analyzed using PROC GLM of SAS (SAS Institute Inc, Cary, North Carolina, USA). A model was fit using all the responses to determine the significant interactions (p < 0.05). Results of this study indicated that storage conditions and storage time have significant impact on the strength of bilayer tablets. For Avicel–lactose and lactose–Avicel tablets, tablet strength decreased with the increasing humidity and storage time. But for lactose–lactose tablets, due to the formation of solid bridges upon storage, an increase in tablet strength was observed. Significant interactions were observed between processing parameters and storage conditions on the strength of bilayer tablets.

Electronic supplementary material

The online version of this article (doi:10.1208/s12249-012-9846-8) contains supplementary material, which is available to authorized users.KEY WORDS: axial tester, bilayer tablet, design of experiments, storage conditions, tablet strength     

Extent and consistency of linkage disequilibrium and identification of DNA markers for production and egg quality traits in commercial layer chicken populations

Background

The genome sequence and a high-density SNP map are now available for the chicken and can be used to identify genetic markers for use in marker-assisted selection (MAS). Effective MAS requires high linkage disequilibrium (LD) between markers and quantitative trait loci (QTL), and sustained marker-QTL LD over generations. This study used data from a 3,000 SNP panel to assess the level and consistency of LD between single nucleotide polymorphisms (SNPs) over consecutive years in two egg-layer chicken lines, and analyzed one line by two methods (SNP-wise association and genome-wise Bayesian analysis) to identify markers associated with egg-quality and egg-production phenotypes.

Results

The LD between markers pairs was high at short distances (r² > 0.2 at < 2 Mb) and remained high after one generation (correlations of 0.80 to 0.92 at < 5 Mb) in both lines. Single- and 3-SNP regression analyses using a mixed model with SNP as fixed effect resulted in 159 and 76 significant tests (P < 0.01), respectively, across 12 traits. A Bayesian analysis called BayesB, that fits all SNPs simultaneously as random effects and uses model averaging procedures, identified 33 SNPs that were included in the model >20% of the time (φ > 0.2) and an additional ten 3-SNP windows that had a sum of φ greater than 0.35. Generally, SNPs included in the Bayesian model also had a small P-value in the 1-SNP analyses.

Conclusion

High LD correlations between markers at short distances across two generations indicate that such markers will retain high LD with linked QTL and be effective for MAS. The different association analysis methods used provided consistent results. Multiple single SNPs and 3-SNP windows were significantly associated with egg-related traits, providing genomic positions of QTL that can be useful for both MAS and to identify causal mutations.

     

Simple Chromatographic Method for Simultaneous Analyses of Phosphatidylcholine, Lysophosphatidylcholine, and Free Fatty Acids

This study describes a simple chromatographic method for the simultaneous analyses of phosphatidylcholine (PC) and its hydrolytic degradation products: lysophosphatidylcholine (LPC) and free fatty acids (FFA). Quantitative determination of PC, LPC, and FFA is essential in order to assure safety and to accurately assess the shelf life of phospholipid-containing products. A single-run normal-phase high-performance liquid chromatography (HPLC) with evaporative light scattering detector has been developed. The method utilizes an Allsphere silica analytical column and a gradient elution with mobile phases consisting of chloroform: chloroform–methanol (70:30%, v/v) and chloroform–methanol–water–ammonia (45:45:9.5:0.5%, v/v/v/v). The method adequately resolves PC, LPC, and FFA within a run time of 25 min. The quantitative analysis of PC and LPC has been achieved with external standard method. The free fatty acids were analyzed as a group using linoleic acid as representative standard. Linear calibration curves were obtained for PC (1.64–16.3 μg, r² = 0.9991) and LPC (0.6–5.0 μg, r² = 0.9966), while a logarithmic calibration curve was obtained for linoleic acid (1.1–5.8 μg, r² = 0.9967). The detection and quantification limits of LPC and FFA were 0.04 and 0.1 μg, respectively. As a means of validating the applicability of the assay to pharmaceutical products, PC liposome was subjected to alkaline hydrolytic degradation. Quantitative HPLC analysis showed that 97% of the total mass balance for PC could be accounted for in liposome formulation. The overall results show that the HPLC method could be a useful tool for chromatographic analysis, stability studies, and formulation characterization of phospholipid-based pharmaceuticals.KEY WORDS: evaporative light scattering detection, free fatty acid, lysophosphatidylcholine, phosphatidylcholine     

Age-related alteration of arginase activity impacts on severity of leishmaniasis

Background

The leishmaniases are a group of vector-borne parasitic diseases that represent a major international public health problem; they belong to the most neglected tropical diseases and have one of the highest rates of morbidity and mortality. The clinical outcome of infection with Leishmania parasites depends on a variety of factors such as parasite species, vector-derived products, genetics, behaviour, and nutrition. The age of the infected individuals also appears to be critical, as a significant proportion of clinical cases occur in children; this age-related higher prevalence of disease is most remarkable in visceral leishmaniasis. The mechanisms resulting in this higher incidence of clinical disease in children are poorly understood. We have recently revealed that sustained arginase activity promotes uncontrolled parasite growth and pathology in vivo. Here, we tested the hypothesis that arginase-mediated L-arginine metabolism differs with age.

Methodology

The age distribution of patients with visceral or cutaneous leishmaniasis was determined in cohorts of patients in our clinics in endemic areas in Ethiopia. To exclude factors that are difficult to control in patients, we assessed the impact of ageing on the manifestations of experimental leishmaniasis. We determined parasite burden, T cell responses, and macrophage effector functions in young and aged mice during the course of infection.

Results

Our results show that younger mice develop exacerbated lesion pathology and higher parasite burdens than aged mice. This aggravated disease development in younger individuals does not correlate with a change in T helper cytokine profile. To address the underlying mechanisms responsible for the more severe infections in younger mice, we investigated macrophage effector functions. Our results show that macrophages from younger mice do not have an impaired capacity to kill parasites; however, they express significantly higher levels of arginase 1 than aged mice and promote parasite growth more efficiently. Thus, our results demonstrate that ageing differentially impacts on L-arginine metabolism and subsequent effector functions of physiologically distinct macrophage subsets.

Conclusions

Here, we show that arginase-mediated L-arginine metabolism is modulated with age and affects the capacity of macrophages to express arginase; the increased capacity to upregulate this enzyme in younger individuals results in a more permissive environment for parasite growth, increased disease severity and pathology. These results suggest that the difference in arginase-mediated L-arginine catabolism is likely to be an important factor contributing to the increased incidence of clinical cases in children. Thus, targeting L-arginine metabolism might be a promising therapeutic strategy against leishmaniasis, especially in children and young adults.     

Immunity against HIV/AIDS, malaria, and tuberculosis during co-infections with neglected infectious diseases: recommendations for the European Union research priorities

Infectious diseases remain a major health and socioeconomic problem in many low-income countries, particularly in sub-Saharan Africa. For many years, the three most devastating diseases, HIV/AIDS, malaria, and tuberculosis (TB) have received most of the world's attention. However, in rural and impoverished urban areas, a number of infectious diseases remain neglected and cause massive suffering. It has been calculated that a group of 13 neglected infectious diseases affects over one billion people, corresponding to a sixth of the world's population. These diseases include infections with different types of worms and parasites, cholera, and sleeping sickness, and can cause significant mortality and severe disabilities in low-income countries. For most of these diseases, vaccines are either not available, poorly effective, or too expensive. Moreover, these neglected diseases often occur in individuals who are also affected by HIV/AIDS, malaria, or TB, making the problem even more serious and indicating that co-infections are the rule rather than the exception in many geographical areas. To address the importance of combating co-infections, scientists from 14 different countries in Africa and Europe met in Addis Ababa, Ethiopia, on September 9-11, 2007. The message coming from these scientists is that the only possibility for winning the fight against infections in low-income countries is by studying, in the most global way possible, the complex interaction between different infections and conditions of malnourishment. The new scientific and technical tools of the post-genomic era can allow us to reach this goal. However, a concomitant effort in improving education and social conditions will be needed to make the scientific findings effective.     

Ex vivo cytokine mRNA levels correlate with changing clinical status of ethiopian TB patients and their contacts over time

There is an increasing body of evidence which suggests that IL-4 plays a role in the pathogenesis of TB, but a general consensus on its role remains elusive. We have previously published data from a cohort of Ethiopian TB patients, their contacts, and community controls suggesting that enhanced IL-4 production is associated with infection with M. tuberculosis, rather than overt disease and that long-term protection in infected community controls is associated with co-production of the IL-4 antagonist IL-4d2, alongside elevated IL-4. Here, for the first time, we compare data on expression of IFN-gamma, IL-4 and IL-4delta2 over time in TB patients and their household contacts. During the follow-up period, the TB patients completed therapy and ceased to display TB-like symptoms. This correlated with a decrease in the relative amount of IL-4 expressed. Over the same period, the clinical status of some of their contacts also changed, with a number developing TB-like symptoms or clinically apparent TB. IL-4 expression was disproportionately increased in this group. The findings support the hypothesis that elevated IL-4 production is generally associated with infection, but that TB disease is associated with a relatively increased expression of IL-4 compared to IFN-gamma and IL-4delta2. However, the data also suggest that there are no clear-cut differences between groups: the immune response over time appears to include changes in the expression of IFN-gamma, IL-4 and IL-4delta2, and it is the relative, not absolute levels of cytokine expression that are characteristic of clinical status.     

长毛速掘鼠的生态学以及对埃塞俄比亚中部Angacha地区农田的影响

于2005年8月-2006年4月研究了埃塞俄比亚Angacha地区农田中的长毛速掘鼠的分布、多度以及影响.通过直接计数地面的新隆起来估计速掘鼠的分布和多度,通过分析胃容物确定了四个地区(分别代表了"凉爽"和"温暖"的温带气候区)速掘鼠的食物成分.通过挖洞和鼠夹捕捉发现,两个凉爽区域内速掘鼠的数量分别为12只/ha和15只/ha,而温暖区域内的数量分别为7只/ha和10只/ha.捕捉到31只活体,其中包括22只成体和9只幼体.性比为2.1∶1.0(雄性∶雌性).与农田相比,长毛速掘更喜爱开阔的草地以延长其采食隧道.水沟、土地肥力和食物资源的可得性是减少洞穴系统长度(11.3-18.6 m)的主要因素.雌、雄鼠隐蔽洞(Bolthole)、卧室、采食隧道的长度和深度无显著差异.速掘鼠取食人类种植的埃塞俄比亚蕉和马铃薯所造成的损失占本地经济损失的12%,控制鼠害的关键是发展合适的控制方法以将对埃塞俄比亚蕉种植的影响减少到最低程度.     

Granulation by Roller Compaction and Enteric Coated Tablet Formulation of the Extract of the Seeds of <Emphasis Type="BoldItalic">Glinus Lotoides</Emphasis> Loaded on Aeroperl® 300 Pharma

The purpose of this research was to improve the hygroscopicity and poor flow properties of the crude dry extract of the seeds of Glinus lotoides and improve the disintegration time of the core-tablets for enteric coated formulation thereof. The liquid crude extract of the plant was adsorbed on granulated colloidal silicon dioxide (Aeroperl 300 Pharma) at 30% w/w and the dry extract preparation (DEP) was dry-granulated with roller-compaction using Micro-Pactor. Hygroscopicity, flow property and disintegration time were improved significantly due to the adsorption and granulation processes. Moreover, the DEP does not become mucilaginous even at higher relative humidity levels (above 65%). Oblong tablets (20 x 8.25 mm) containing 947 mg of the granulated DEP (equivalent to the traditional dose), 363 mg of Avicel PH101 and 90 mg of Ac-di-Sol as disintegrant were formulated using an instrumented eccentric tablet machine at 20 kN. The tablets showed a crushing strength of 195 N, a friability of 0.4% and disintegrated within 9 min. The tablets were then enteric coated using polymethacrylate co-polymers (Eudragit L 100-55 and Kollicoat MAE 100P). The coated tablets resisted disintegration or softening in simulated gastric fluid for a minimum of 2 h and disintegrated within 15 min in intestine simulated fluid at pH 6.8. In addition to controlling the release of the active agents, the enteric coating improved the strength and decreased friability of the core-tablets.