Impact of <Emphasis Type="Italic">Plasmodium falciparum</Emphasis> infection on haematological parameters in children living in Western Kenya

Background

Malaria is the commonest cause of childhood morbidity in Western Kenya with varied heamatological consequences. The t study sought to elucidate the haemotological changes in children infected with malaria and their impact on improved diagnosis and therapy of childhood malaria.

Methods

Haematological parameters in 961 children, including 523 malaria-infected and 438 non-malaria infected, living in Kisumu West District, an area of malaria holoendemic transmission in Western Kenya were evaluated.

Results

The following parameters were significantly lower in malaria-infected children; platelets, lymphocytes, eosinophils, red blood cell count and haemoglobin (Hb), while absolute monocyte and neutrophil counts, and mean platelet volume (MPV) were higher in comparison to non-malaria infected children. Children with platelet counts of <150,000/uL were 13.8 times (odds ratio) more likely to have malaria. Thrombocytopaenia was present in 49% of malaria-infected children and was associated with high parasitaemia levels, lower age, low Hb levels, increased MPV and platelet aggregate flag. Platelet aggregates were more frequent in malaria-infected children (25% vs. 4%, p<0.0001) and associated with thrombocytopaenia rather than malaria status.

Conclusion

Children infected with Plasmodium falciparum malaria exhibited important changes in some haematological parameters with low platelet count and haemoglobin concentration being the two most important predictors of malaria infection in children in our study area. When used in combination with other clinical and microscopy, these parameters could improve malaria diagnosis in sub-patent cases.

     

Does surface textural complexity of woody debris in lotic ecosystems influence their colonization by aquatic invertebrates?

Materials retained by river systems are diverse. Woody debris recruited from the riparian vegetation into streams is of variable sizes and varying surface textural complexity. The main aim of this study was to determine experimentally the colonization of wood recruited into a tropical stream by aquatic invertebrates and relate this to the degree of wood surface textural complexity. Wood, being alien to the wholly-aquatic and semi-aquatic invertebrates, provided an attachment substratum and was increasingly colonized by the invertebrates up to the 178th day. There was an initial increase in the taxa diversity up to the 9th day followed by a drastic decrease thereafter. Wood with smaller surface area had the higher invertebrate densities than those with large surface area, thus contrasting the expected trend. Our results show that the colonization by invertebrates of wood was scale-dependent. Invertebrates occupied the cracks, holes, protrusions, crevices and the small depressions found on the wood surface. Chironomidae (Order Diptera) made small tunnels in the more decayed parts of the wood and at the nodal areas. Wood decomposes slowly but it could cumulatively contribute more energy in its lifespan than the short-lived leaf litter which is more abundant in streams. Aquatic invertebrates encountering woody material in nature would make a trade-off between accepting a long-lasting resource and expending energy in continued search for the more palatable short-lived leafy material. The ecological and economic value of wood texture in streams and riparian vegetation management are poorly known and there is need for further research in the tropics.     

Acceptance and suitability of four lepidopteran stemborers for the development of the pupal parasitoid Xanthopimpla stemmator (Hymenoptera: Ichneumonidae)

Xanthopimpla stemmator (Thunberg), a solitary endoparasitoid of lepidopteran stemborer pupae, was recently imported into East Africa as a candidate biological control agent of gramineous stemborers. Suitability of Busseola fusca Fuller, Chilo partellus (Swinhoe), Eldana saccharina (Walker) and Sesamia calamistis Hampson, for the development of X. stemmator was studied in the laboratory. One- to 6-day-old laboratory reared pupae of the four stemborer species were exposed to naïve X. stemmator females. All host pupae and ages were acceptable for oviposition. The parasitoids inflicted multiple probe wounds on 67.8% of pupae exposed. B. fusca, C. partellus and S. calamistis were equally suitable with 56.4, 59.4 and 52.3%, respectively, of probed pupae leading to emergence of adult parasitoids. E. saccharina was less suitable with only 22.6% of probed pupae producing parasitoids. Emergence of parasitoids did not differ significantly across the six pupal ages for B. fusca and S. calamistis, but varied for C. partellus and E. saccharina. No parasitoids emerged from 6-day-old E. saccharina pupae. Realized fecundity of females reared on the four stemborer pupae showed that fewer progeny were produced by females emerging from E. saccharina than females reared on the other three stemborer species. Eldana saccharina may be a poor host for X. stemmator in Kenya, but this parasitoid is a potential candidate for biological control of B. fusca, C. partellus and S. calamistis.     

Brassinosteroids Alleviate Heat-Induced Inhibition of Photosynthesis by Increasing Carboxylation Efficiency and Enhancing Antioxidant Systems in <Emphasis Type="Italic">Lycopersicon esculentum</Emphasis>

To investigate the effects of exogenously applied brassinosteroids on the thermotolerance of plants, leaf CO₂ assimilation, chlorophyll fluorescence parameters, and antioxidant enzyme metabolism were examined in tomato (Lycopersicon esculentum Mill. cv. 9021) plants with or without 24-epibrassinolide (EBR) application. Tomato plants were exposed to 40/30°C for 8 days and then returned to optimal conditions for 4 days. High temperature significantly decreased the net photosynthetic rate (P _n), stomatal conductance (G _s), and maximum carboxylation rate of Rubisco (V _cmax), the maximum potential rate of electron transport contributed to ribulose-1,5-bisphosphate (RuBP), as well as the relative quantum efficiency of PSII photochemistry (Ф_PSII), photochemical quenching (q _P), and increased nonphotochemical quenching (NPQ). However, only slight reversible photoinhibition occurred during heat stress. Interestingly, EBR pretreatment significantly alleviated high-temperature-induced inhibition of photosynthesis. The activities of antioxidant enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPOD), and catalase (CAT) increased during heat treatments, and these increases proved to be more significant in EBR-treated plants. EBR application also reduced total hydrogen peroxide (H₂O₂) and malonaldehyde (MDA) contents, while significantly increasing shoot weight following heat stress. It was concluded that EBR could alleviate the detrimental effects of high temperatures on plant growth by increasing carboxylation efficiency and enhancing antioxidant enzyme systems in leaves.     

Haplotypes of IL-10 promoter variants are associated with susceptibility to severe malarial anemia and functional changes in IL-10 production

Plasmodium falciparum malaria is one of the leading global causes of morbidity and mortality with African children bearing the highest disease burden. Among the various severe disease sequelae common to falciparum malaria, severe malarial anemia (SMA) in pediatric populations accounts for the greatest degree of mortality. Although the patho-physiological basis of SMA remains unclear, dysregulation in inflammatory mediators, such as interleukin (IL)-10, appear to play an important role in determining disease outcomes. Since polymorphic variability in innate immune response genes conditions susceptibility to malaria, the relationship between common IL-10 promoter variants (−1,082A/G, −819T/C, and −592A/C), SMA (Hb < 6.0 g/dL), and circulating inflammatory mediator levels (i.e., IL-10, TNF-α, IL-6 and IL-12) were investigated in parasitemic Kenyan children (n = 375) in a holoendemic P. falciparum transmission area. Multivariate logistic regression analyses demonstrated that the −1,082G/−819C/−592C (GCC) haplotype was associated with protection against SMA (OR; 0.68, 95% CI, 0.43–1.05; P = 0.044) and increased IL-10 production (P = 0.029). Although none of the other haplotypes were significantly associated with susceptibility to SMA, individuals with the −1,082A/−819T/−592A (ATA) haplotype had an increased risk of SMA and reduced circulating IL-10 levels (P = 0.042). Additional results revealed that the IL-10:TNF-α ratio was higher in the GCC group (P = 0.024) and lower in individuals with the ATA haplotype (P = 0.034), while the IL-10:IL-12 ratio was higher in ATA haplotype (P = 0.006). Results presented here demonstrate that common IL-10 promoter haplotypes condition susceptibility to SMA and functional changes in circulating IL-10, TNF-α, and IL-12 levels in children with falciparum malaria. The study was approved by the ethical and scientific review committees at the Kenya Medical Research Institute and the institutional review board at the University of Pittsburgh.     

Adequacy of control of cardiovascular risk factors in ambulatory patients with type 2 diabetes attending diabetes out-patients clinic at a county hospital,Kenya

Background

Type 2 diabetes is associated with substantial cardiovascular morbidity and mortality arising from the high prevalence of cardiovascular risk factors such as hypertension, dyslipidaemia, obesity, poor glycaemic control and albuminuria. Adequacy of control of these risk factors determines the frequency and outcome of cardiovascular events in the patients. Current clinical practice guidelines emphasize primary prevention of cardiovascular disease in type 2 diabetes. There is scarce data from the developing countries, Kenya included, on clinical care of patients with type 2 diabetes in the regions that are far away from tertiary health facilities. So we determined the adequacy of control of the modifiable risk factors: glycaemic control, hypertension, dyslipidemia, obesity and albuminuria in the study patients from rural and peri-urban dwelling.

Methods

This was a cross-sectional study on 385 randomly selected ambulatory patients with type 2 diabetes without overt complications. They were on follow up for at least 6 months at the Out-patient diabetes clinic of Nyeri County Hospital, a public health facility located in the central region of Kenya.

Results

Females were 65.5%. The study subjects had a mean duration of diabetes of 9.4 years, IQR of 3.0–14 years. Their mean age was 63.3 years, IQR of 56-71 years.Only 20.3% of our subjects had simultaneous optimal control of the three (3) main cardiovascular risk factors of hypertension, high LDL-C and hyperglycaemia at the time of the study. The prevalence of cardiovascular risk factors were as follows: HbA1c above 7% was 60.5% (95% CI, 55.6–65.5), hypertension, 49.6% of whom 76.6% (95% CI, 72.5–80.8) were poorly controlled. High LDL-Cholesterol above 2.0 mmol/L was found in 77.1% (95% CI 73.0–81.3) and Albuminuria occurred in 32.7% (95% CI 27.8–37.4). The prevalence of the other habits with cardiovascular disease risk were: excess alcohol intake at 26.5% (95% CI 27.8–37.4) and cigarette-smoking at 23.6%.A modest 23.4% of the treated patients with hypertension attained target blood pressure of <140/90 mmHg. Out of a paltry 12.5% of the statin-treated patients and others not actively treated, only 22.9% had LDL-Cholesterol of target <2.0 mmol/L.There were no obvious socio-demographic and clinical determinants of poor glycaemic control. However, old age above 50 yrs., longer duration with diabetes above 5 yrs. and advanced stages of CKD were significantly associated with hypertension. Female gender and age, statin non-use and socio-economic factor of employment were the significant determinants of high levels of serum LDL-cholesterol.

Conclusion

The majority of the study patients attending this government-funded health facility had high prevalence of cardiovascular risk factors that were inadequately controlled. Therefore patients with type 2 diabetes should be risk-stratified by their age, duration of diabetes and cardiovascular risk factor loading. Consequently, composite risk factor reduction strategies are needed in management of these patients to achieve the desired targets safely. This would be achieved through innovative care systems and modes of delivery which would translate into maximum benefit of primary cardiovascular disease prevention in those at high risk. It is a desirable quality objective to have a higher proportion of the patients who access care benefiting maximally more than the numbers we are achieving now.

     

Timing and location of reproduction in African waterfowl: an overview of >100 years of nest records

The timing and location of reproduction are fundamental elements of reproductive success for all organisms. Understanding why animals choose to reproduce at particular times and in particular places is also important for our understanding of other aspects of organismal ecology, such as their habitat requirements, movement strategies, and biogeography. Although breeding patterns in waterfowl are relatively well documented, most studies are from northern temperate regions and the influences of location and time of year on breeding in Afrotropical ducks (Anatidae) are poorly understood. We outline six alternative (but not mutually exclusive) hypotheses that might explain where and when Afrotropical ducks choose to breed. To explore these hypotheses, we assembled and analyzed a new database of c. 22,000 breeding records for 16 Afrotropical ducks and one introduced Palearctic species (the Mallard Anas platyrhynchos). The full database is available on line as an appendix to this article. We identified five distinct breeding strategies as well as two outliers. Peak breeding for 9 of 16 indigenous duck species occurs during the dry season. We found no evidence for spatial synchrony or spatial autocorrelation in breeding, suggesting a high level of flexibility in waterfowl responses to prevailing conditions in any given year. More intensive analyses of alternative hypotheses are needed, but our initial analysis suggests that the timing of breeding for the majority of Afrotropical ducks is driven by a combination of resource availability and predation risk.     

Discovery of a novel potent GPR40 full agonist

Compound 12 is a GPR40 agonist that realizes the full magnitude of efficacy possible via GPR40 receptor agonism. In vitro and in vivo studies demonstrated superior glucose lowering by 12 compared to fasiglifam (TAK-875), in a glucose dependent manner. The enhanced efficacy observed with the full agonist 12 was associated with both direct and indirect stimulation of insulin secretion.     

Combining evidence of natural selection with association analysis increases power to detect malaria-resistance variants

Statistical power to detect disease variants can be increased by weighting candidates by their evidence of natural selection. To demonstrate that this theoretical idea works in practice, we performed an association study of 10 putative resistance variants in 471 severe malaria cases and 474 controls from the Luo in Kenya. We replicated associations at HBB (P=.0008) and CD36 (P=.03) but also showed that the same variants are unusually differentiated in frequency between the Luo and Yoruba (who historically have been exposed to malaria) and the Masai and Kikuyu (who have not been exposed). This empirically demonstrates that combining association analysis with evidence of natural selection can increase power to detect risk variants by orders of magnitude--up to P=.000018 for HBB and P=.00043 for CD36.     

Quantitative variation in seeds,seedling growth and biomass among Acacia senegal (L) Willd. provenances in Kenya

Conventionally, local seed sources are normally believed to perform better than introduced materials. However, studies show possibility of contrary results with many species such as Acacia senegal. The species is an economically and ecologically important tree of arid and semi‐arid lands of sub‐Saharan Africa. It produces gum arabic, used in land reclamation and agroforestry production. The species is however underutilized in Kenya due to lack of information on growth performance of different seed sources. Glasshouse provenance trial using seeds and soils from seven provenances in Kenya were used to evaluate interactions between seed sources and soils on growth and biomass. Seedling growth was assessed for 12 weeks in a randomized complete block design. Seed length, width, thickness and weight were measured. Seedlings height, root collar diameter, root dry weight, shoot dry weight and biomass were assessed and data subjected to univariate and multivariate analyses. No significant interaction between seed provenance and soils were evident; however, some provenances performed better across all the soils. Significant heritability and relationship between growth and environmental factors are reported. Overall, Ntumburi and Ngarendare provenances showed superior growth and plasticity. These provenances can be used tentatively as seed sources; however, field trials are recommended.