Diffusion-Weighted MR Imaging in a Prospective Cohort of Children with Cerebral Malaria Offers Insights into Pathophysiology and Prognosis

BACKGROUND AND PURPOSE

Validation of diffusion-weighted images obtained on 0.35T MR imaging in Malawi has facilitated meaningful review of previously unreported findings in cerebral malaria. Malawian children with acute cerebral malaria demonstrated restricted diffusion on brain MR imaging, including an unusual pattern of restriction isolated to the subcortical white matter. We describe the patterns of diffusion restriction in cerebral malaria and further evaluate risk factors for and outcomes associated with an isolated subcortical white matter diffusion restriction.

MATERIALS AND METHODS

Between 2009 and 2014, comatose Malawian children admitted to the hospital with cerebral malaria underwent admission brain MR imaging. Imaging data were compiled via NeuroInterp, a RedCap data base. Clinical information obtained included coma score, serum studies, and coma duration. Electroencephalograms were obtained between 2009 and 2011. Outcomes captured included death, neurologic sequelae, or full recovery.

RESULTS

One hundred ninety-four/269 (72.1%) children with cerebral malaria demonstrated at least 1 area of diffusion restriction. The most common pattern was bilateral subcortical white matter involvement (41.6%), followed by corpus callosum (37.5%), deep gray matter (36.8%), cortical gray matter (17.8%), and posterior fossa (8.9%) involvement. Sixty-one (22.7%) demonstrated isolated subcortical white matter diffusion restriction. These children had lower whole-blood lactate levels (OR, 0.9; 95% CI, 0.85-0.98), were less likely to require anticonvulsants (OR, 0.6; 95% CI, 0.30-0.98), had higher average electroencephalogram voltage (OR, 1.01; 95% CI, 1.00-1.02), were less likely to die (OR, 0.09; 95% CI, 0.01-0.67), and were more likely to recover without neurologic sequelae (OR, 3.7; 95% CI, 1.5-9.1).

CONCLUSIONS

Restricted diffusion is common in pediatric cerebral malaria. Isolated subcortical white matter diffusion restriction is a unique imaging pattern associated with less severe disease and a good prognosis for full recovery. The underlying pathophysiology may be related to selective white matter vulnerability.

Demographic factors shaped diversity in the two gene pools of wild common bean Phaseolus vulgaris L

Wild common bean (Phaseolus vulgaris L.) is distributed throughout the Americas from Mexico to northern Argentina. Within this range, the species is divided into two gene pools (Andean and Middle American) along a latitudinal gradient. The diversity of 24 wild common bean genotypes from throughout the geographic range of the species was described by using sequence data from 13 loci. An isolation-migration model was evaluated using a coalescent analysis to estimate multiple demographic parameters. Using a Bayesian approach, Andean and Middle American subpopulations with high percentage of parentages were observed. Over all loci, the Middle American gene pool was more diverse than the Andean gene pool (π(sil)=0.0089 vs 0.0068). The two subpopulations were strongly genetically differentiated over all loci (F(st)=0.29). It is estimated that the two current wild gene pools diverged from a common ancestor ∼111 000 years ago. Subsequently, each gene pool underwent a bottleneck immediately after divergence and lasted ∼40 000 years. The Middle American bottleneck population size was ∼46% of the ancestral population size, whereas the Andean was 26%. Continuous asymmetric gene flow was detected between the two gene pools with a larger number of migrants entering Middle American gene pool from the Andean gene pool. These results suggest that because of the complex population structure associated with the ancestral divergence, subsequent bottlenecks in each gene pool, gene pool-specific domestication and intense selection within each gene pool by breeders; association mapping would best be practised within each common bean gene pool.

The critical role of vascular endothelial growth factor in tumor angiogenesis

Angiogenesis is the formation of new blood vessels from the pre-existing vasculature. Besides its role in normal physiology, angiogenesis is significantly involved in many pathological conditions, including inflammation, cardiovascular diseases and cancer. Numerous studies have been undertaken in the area of tumor angiogenesis. It is known that pathological angiogenesis is necessary for tumors to proceed from avascular, dormant stage to vascular, sprouting stage and also contributes to their later invasion and metastasis. Playing a central role in tumor angiogenesis, vascular endothelial growth factor is considered as a key target in therapeutic approaches. This article aims to review the critical role of VEGF in tumor angiogenesis and the importance of VEGF-targeted strategies in cancer treatment.