Sensitivity To Dihydrofolate Reductase Inhibitors And Molecular Karyotypes In Some Plasmodium Falciparum Isolates In Kenya
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Date
1995Author
Nyalwidhe, Julius O.
Type
ThesisLanguage
enMetadata
Show full item recordAbstract
Ten Kenyan isolates of Plasmodium [alcip arum were characterized by their
molecular karyotype and antimalarial drug sensitivity. For chromosomal analysis pulse
field gradient gel electrophoresis was used. Plasmodium jalciparum isolates from
malarious areas in Nyanza. Rift Valley and Coast provinces were cultivated ill vitro and
used for the karyotype study. The sensitivities of cultured isolates to three antifolate
malarial drugs (pyrimethamine, cycloguanil and chlorcycloguanil) and sulphadoxine
which is a sulphonamide were examined by the ill vitro radioisotopic methods of
Desjardins et al. (1979) with minor modifications.
Considerable variation was found in the antimalarial drug response of the 10
parasite isolates. Among the four antimalarial drugs examined, chlorcycloguanil and
cycloguanil had similar potencies. They were more potent than pyrimethamine and
sulphadoxine. Sulphadoxine and pyrimethamine had similar potencies. Cycloguanil and
chlorcycloguanil, which are closely related biguanides were highly correlated in their
antimalarial activities. There was no correlation between the activity of the three
antifolates and sulphadoxine.
The isolates from the Rift Valley province showed significantly lower
susceptibility to the four antimalarial drugs tested than those from the Coast and Nyanza
provinces. The isolates from Coast province showed the highest susceptibility.
The chromosomal bands were found to range- in number from 14 to 16 and in size
from 600 to 4300 kilobase pairs, and there was extensive variation in chromosome size.
Two isolates had more than the constant number of chromosomes, suggesting a mixed
population of parasite strains in natural malarial infections.There were inter and intraregional
differences in the sizes of the chromosomes. However. there was no correlation
between band size and drug sensitivity. The degree of polymorphism shown by the
chromosomes was such that each isolate could be individually characterised by its
chromosomal pattern.
Citation
Master of Science (Parasitology)Publisher
University of Nairobi School of Biological Sciences