Biomedical subjects

Raphael D Isokpehi

Publications and source records attributed to Raphael D Isokpehi.

3 recordsLinked to original sources

PubMed2004

Positive selection scanning of parasite DNA sequences.

Parasites successfully exist within the host as a result of highly specific genetic adaptations. Therefore, detecting genes that contain relevant adaptive mutations can provide a guide to biological processes that are potentially essential to the parasite. Random genetic mutations that confer selective advantage can act to alter amino acids so as to confer gain of function that has positive impact on the survival of the parasite. Directional selection of advantageous mutations results from an elevated rate of nonsynonymous substitutions in rapidly evolving genes. Genes on which this positive selection operates are considered to have an evolutionary characteristic such that the normalized number of nonsynonymous (dn) substitutions is greater than that of synonymous (ds) substitutions. By searching in a statistically robust way for genes that contain this characteristic, it is possible to apply a stringent method to identify genes that may be under positive selection and thus to identify biological processes involving those genes that are essential to the survival of the parasite. Genes detected typically class into those under host immune surveillance and those intrinsic to pathways essential to survival of the parasite within the host. Depending on their function and location of protein expression, such genes have the potential to provide exceptional vaccine and drug candidates.

Amino Acid Sequence↗

PubMed2003

Integrative analysis of intraerythrocytic differentially expressed transcripts yields novel insights into the biology of Plasmodium falciparum.

BACKGROUND: The intraerythrocytic development of Plasmodium falciparum, the most virulent human malaria parasite involves asexual and gametocyte stages. There has been a significant increase in disparate datasets derived from genomic and post-genomic analysis of the parasite that necessitates delivery of integrated analysis from which biological processes important to the survival of the parasite can be determined. METHODS: In order to resolve genes associated with stage differentially expressed transcripts, we have developed and implemented an integrative approach that combines evidence from P. falciparum expressed sequence tags (ESTs), genomic, microarray, proteomic and gene ontology data. RESULTS: A total of 143 gametocyte-overexpressed and 51 asexual-overexpressed transcripts were identified. A subset of 74 genes associated with these transcripts showed evidence of stage-correlated protein expression, of which 53 have not been experimentally characterised. Our study has revealed (1) possible regulatory mechanisms in malaria parasites' gametocyte maturation, (2) correlation between EST and microarray data for a P. falciparum gene family to present unique EST-derived information, (3) candidate drug and antigenic targets on which computational and experimental studies can be performed, and (4) the need for more empirical studies on gene and protein expression in malaria parasites. CONCLUSION: Applying different domains of data to the same underlying gene set has yielded novel insights into the biology of the parasite and presents an approach to appraise critically the data quality of post-genomic datasets from malaria parasites.

Journal Article↗

PubMed2002

Human campylobacteriosis in developing countries.

Campylobacteriosis is a collective description for infectious diseases caused by members of the bacterial genus Campylobacter. The only form of campylobacteriosis of major public health importance is Campylobacter enteritis due to C. jejuni and C. coli. Research and control efforts on the disease have been conducted more often in developed countries than developing countries. However, because of the increasing incidence, expanding spectrum of infections, potential of HIV-related deaths due to Campylobacter, and the availability of the complete genome sequence of C. jejuni NCTC 11168, interest in campylobacteriosis research and control in developing countries is growing. We present the distinguishing epidemiologic and clinical features of Campylobacter enteritis in developing countries relative to developed countries. National surveillance programs and international collaborations are needed to address the substantial gaps in the knowledge about the epidemiology of campylobacteriosis in developing countries.

Campylobacter Infections↗