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Background: Malaria is still one of the serious public health problems in Grande Comore Island, although the number of annual cases has been greatly reduced in recent years. A better understanding of malaria parasite population diversity and transmission dynamics is critical for assessing the effectiveness of malaria control measures. The objective of this study is to investigate temporal changes in genetic diversity of Plasmodium falciparum populations and multiplicity of infection (MOI) in Grande Comore 10 years after introduction of ACT. Methods: A total of 232 P. falciparum clinical isolates were collected from the Grande Comore Island during two sampling periods (118 for 2006‒2007 group, and 114 for 2013‒2016 group). Parasite isolates were characterized for genetic diversity and complexity of infection by genotyping polymorphic regions in merozoite surface protein gene 1 (msp-1), msp-2, and msp-3 using nested PCR and DNA sequencing. Results: Three msp-1 alleles (K1, MAD20, and RO33), two msp-2 alleles (FC27 and 3D7), and two msp-3 alleles (K1 and 3D7) were detected in parasites of both sampling periods. The RO33 allele of msp-1 (84.8%), 3D7 allele of msp-2 (90.8%), and K1 allele of msp-3 (66.7%) were the predominant allelic types in isolates from 2006–2007 group. In contrast, the RO33 allele of msp-1 (63.4%), FC27 allele of msp-2 (91.1%), and 3D7 allele of msp-3 (53.5%) were the most prevalent among isolates from the 2013–2016 group. Compared with the 2006‒2007 group, polyclonal infection rates of msp-1 (from 76.7 to 29.1%, P < 0.01) and msp-2 (from 62.4 to 28.3%, P < 0.01) allelic types were significantly decreased in those from 2013‒2016 group. Similarly, the MOIs for both msp-1 and msp-2 were higher in P. falciparum isolates in the 2006–2007 group than those in 2013–2016 group (MOI = 3.11 vs 1.63 for msp-1; MOI = 2.75 vs 1.35 for msp-2). DNA sequencing analyses also revealed reduced numbers of distinct sequence variants in the three genes from 2006‒2007 to 2013‒2016: msp-1, from 32 to 23 (about 28% decline); msp-2 from 29 to 21 (about 28% decline), and msp-3 from 11 to 3 (about 72% decline). Conclusions: The present data showed dramatic reduction in genetic diversity and MOI among Grande Comore P. falciparum populations over the course of the study, suggesting a trend of decreasing malaria transmission intensity and genetic diversity in Grande Comore Island. These data provide valuable information for surveillance of P. falciparum infection and for assessing the appropriateness of the current malarial control strategies in the endemic area. [ABSTRACT FROM AUTHOR]

Objective To investigate the expression of semaphorin 6D (SEMA6D) and Snail and their clinicopathological implications in gastric cancer. Methods 54 cases of gastric cancer tissues and 26 paracancerous gastric mucosa were collected for detecting the expression of SEMA6D and Snail by immunohistochemistry and Western blot analysis. The co-localization of SEMA6D and Snail was observed by immunofluorescence double staining and laser scanning confocal microscopy. The correlation between SEMA6D and Snail and their relationships with the clinicopathological features of the patients were analyzed. Results Compared with the paracancerous gastric mucosa, the protein expression of SEMA6D and Snail in the gastric cancer significantly increased, and there was a significant co-localization of SEMA6D and Snail in gastric cancer. Further statistical analysis showed that the expression of SEMA6D and Snail in gastric cancer was positively correlated with the degree of differentiation, invasion, lymph node metastasis and TNM stage. Conclusion The high expression of SEMA6D and Snail in gastric cancer are related to the malignant clinicopathological indexes of gastric cancer.