Plant community distribution and variation along the Awash river corridor in the main Ethiopian rift

The vegetation along the Awash River (1200-km long) in the main Ethiopian Rift, and its relationship with environmental factors was studied. Seven plant communities were described from the study area: (1) Acacia nilotica subsp . leiocarpa. – Carissa edulis type; (2) Acacia robusta subsp . usambarensis – Acokanthera schimperi type; (3) Celtis africana – Mimusops laurifolia type; (4) Acacia senegal – Acacia mellifera – Dobera glabra type; (5) Acacia nilotica subsp. indica – Ficus capreaefolia type; (6) Lannea schimperi – Glycine wightii type; and (7) Tamarix nilotica – Acacia hocki community type. It has been shown that the plant communities along the river follow an altitudinal gradient. The vegetation of the Awash River is mainly the result of the interactions between edaphic factors, the hydrology, altitude, slope and climate.     

Short- and long-term outcomes in infective endocarditis patients: a systematic review and meta-analysis

Background

Despite advances in medical knowledge, technology and antimicrobial therapy, infective endocarditis (IE) is still associated with devastating outcomes. No reviews have yet assessed the outcomes of IE patients undergoing short- and long-term outcome evaluation, such as all-cause mortality and IE-related complications. We conducted a systematic review and meta-analysis to examine the short- and long-term mortality, as well as IE-related complications in patients with definite IE.

Methods

A computerized systematic literature search was carried out in PubMed, Scopus and Google Scholar from 2000 to August, 2016. Included studies were published studies in English that assessed short-and long-term mortality for adult IE patients. Pooled estimations with 95% confidence interval (CI) were calculated with DerSimonian-Laird (DL) random-effects model. Sensitivity and subgroup analyses were also performed. Publication bias was evaluated using inspection of funnel plots and statistical tests.

Results

Twenty five observational studies (retrospective, 14; prospective, 11) including 22,382 patients were identified. The overall pooled mortality estimates for IE patients who underwent short- and long-term follow-up were 20% (95% CI: 18.0–23.0, P?<?0.01) and 37% (95% CI: 27.0–48.0, P?<?0.01), respectively. The pooled prevalence of cardiac complications in patients with IE was found to be 39% (95%CI: 32.0–46.0) while septic embolism and renal complications accounted for 25% (95% CI: 20.0–31) and 19% (95% CI: 14.0–25.0) (all P?<?0.01), respectively.

Conclusion

Irrespective of the follow-up period, a significantly higher mortality rate was reported in IE patients, and the burden of IE-related complications were immense. Further research is needed to assess the determinants of overall mortality in IE patients, as well as well-designed observational studies to conform our results.

     

Ecosystem responses to woody plant encroachment in a semiarid savanna rangeland

Woody plant encroachment alters the structure and function of rangeland ecosystems. The objective of this study was to explore the association between woody plant encroachment and various ecosystem properties (i.e. vascular plant species diversity, richness, evenness, soil organic matter, herbaceous biomass, leaf litter and bare ground cover) in a semiarid savanna rangeland, and also to test whether the relationships were influenced by woody species composition, elevation and site. We carried out a vegetation survey in four rangeland sites in the lower Omo region of southwestern Ethiopia, and regressed each one of the ecosystem properties, separately, against woody plant density, elevation and site using multiple linear regressions. We found that vascular plant species diversity, richness and evenness increased with woody plant density, most likely due to increased spatial heterogeneity and soil microclimate improvement. Bare ground cover increased significantly, whereas herbaceous biomass and soil organic matter did not respond to woody encroachment. In a subsequent investigation, we used a redundancy analysis to assess whether ecosystem properties were influenced by the identity of encroaching woody plant species. Species diversity and richness responded positively to Lannea triphylla, whereas leaf litter responded positively to Grewia tenax and G. villosa. Our findings suggest that woody plant encroachment in a semiarid rangeland does alter ecosystem properties. However, its impact is highly variable, influenced by a set of factors including the level of encroachment and identity of encroaching woody species.     

High-Altitude Rock Shelters and Settlements in an African Alpine Ecosystem: The Bale Mountains National Park,Ethiopia

This first survey of rock shelters and settlements in the Bale Mountains in Ethiopia is a baseline assessment for further research into the settlement history of Africa’s largest alpine highlands. Extensive GPS-based mapping and interviews resulted in two detailed maps, a catalogue of profiles, and complete photographic documentation. In total, 331 rock shelters (four permanently inhabited, 51 seasonally inhabited, and 276 currently uninhabited) and 870 settlements (207 permanently inhabited, 449 seasonally inhabited, 214 uninhabited) were recorded together with information about the activities and livelihoods of the inhabitants of the current settlements. This 2015 study was part of the Ethiopian-European research project “The mountain exile hypothesis – how humans benefited from and re-shaped African high-altitude ecosystems during Quaternary climate changes” (DFG FOR 2358). It was designed to support future management plans in this internationally important conservation area that has recently faced increasing land-use pressure and the threat of degradation.     

Arginase Activity in the Blood of Patients with Visceral Leishmaniasis and HIV Infection

Background

Visceral leishmaniasis is a parasitic disease associated with high mortality. The most important foci of visceral leishmaniasis in Ethiopia are in the Northwest and are predominantly associated with high rates of HIV co-infection. Co-infection of visceral leishmaniasis patients with HIV results in higher mortality, treatment failure and relapse. We have previously shown that arginase, an enzyme associated with immunosuppression, was increased in patients with visceral leishmaniasis and in HIV seropositive patients; further our results showed that high arginase activity is a marker of disease severity. Here, we tested the hypothesis that increased arginase activities associated with visceral leishmaniasis and HIV infections synergize in patients co-infected with both pathogens.

Methodology/Principal Findings

We recruited a cohort of patients with visceral leishmaniasis and a cohort of patients with visceral leishmaniasis and HIV infection from Gondar, Northwest Ethiopia, and recorded and compared their clinical data. Further, we measured the levels of arginase activity in the blood of these patients and identified the phenotype of arginase-expressing cells. Our results show that CD4⁺ T cell counts were significantly lower and the parasite load in the spleen was significantly higher in co-infected patients. Moreover, our results demonstrate that arginase activity was significantly higher in peripheral blood mononuclear cells and plasma of co-infected patients. Finally, we identified the cells-expressing arginase in the PBMCs as low-density granulocytes.

Conclusion

Our results suggest that increased arginase might contribute to the poor disease outcome characteristic of patients with visceral leishmaniasis and HIV co-infection.     

Impact of the Genetic Background on the Composition of the Chicken Plasma MiRNome in Response to a Stress

Circulating extra-cellular microRNAs (miRNAs) have emerged as promising minimally invasive markers in human medicine. We evaluated miRNAs isolated from total plasma as biomarker candidates of a response to an abiotic stress (feed deprivation) in a livestock species. Two chicken lines selected for high (R+) and low (R−) residual feed intake were chosen as an experimental model because of their extreme divergence in feed intake and energy metabolism. Adult R+ and R− cocks were sampled after 16 hours of feed deprivation and again four hours after re-feeding. More than 292 million sequence reads were generated by small RNA-seq of total plasma RNA. A total of 649 mature miRNAs were identified; after quality filtering, 148 miRNAs were retained for further analyses. We identified 23 and 19 differentially abundant miRNAs between feeding conditions and between lines respectively, with only two miRNAs identified in both comparisons. We validated a panel of six differentially abundant miRNAs by RT-qPCR on a larger number of plasma samples and checked their response to feed deprivation in liver. Finally, we evaluated the conservation and tissue distribution of differentially abundant miRNAs in plasma across a variety of red jungle fowl tissues. We show that the chicken plasma miRNome reacts promptly to the alteration of the animal physiological condition driven by a feed deprivation stress. The plasma content of stress-responsive miRNAs is strongly influenced by the genetic background, with differences reflecting the phenotypic divergence acquired through long-term selection, as evidenced by the profiles of conserved miRNAs with a regulatory role in energy metabolism (gga-miR-204, gga-miR-let-7f-5p and gga-miR-122-5p). These results reinforce the emerging view in human medicine that even small genetic differences can have a considerable impact on the resolution of biomarker studies, and provide support for the emerging interest in miRNAs as potential novel and minimally invasive biomarkers for livestock species.     

Arginase Activity - A Marker of Disease Status in Patients with Visceral Leishmaniasis in Ethiopia

The underlying mechanisms resulting in the profound immune suppression characteristic of human visceral leishmaniasis (VL) are not fully understood.Here, we tested the hypothesis that arginase, an enzyme associated with immunosuppression, is higher in patients with VL and contributes to impaired T cell responses. We recruited patients with VL before and after treatment and healthy controls and measured the arginase metabolism in the blood of these individuals. Our results show that arginase activity is significantly higher in the blood of patients with active VL as compared to controls. These high levels of arginase decline considerably once the patients are successfully treated. We identified the phenotype of arginase-expressing cells among PBMCs as neutrophils and show that their frequency was increased in PBMCs of patients before treatment; this coincides with reduced levels of L-arginine in the plasma and decreased expression levels of CD3ζ in T cells.