Biomedical subjects

Katharine K Grady

Publications and source records attributed to Katharine K Grady.

4 recordsLinked to original sources

PubMed2007

The heat stability of Plasmodium lactate dehydrogenase-based and histidine-rich protein 2-based malaria rapid diagnostic tests.

Malaria rapid diagnostic tests (RDTs) have performed well in a variety of studies, but recent reports have described sensitivity for Plasmodium falciparum as significantly lower than that required for operational deployment. Exposure to high temperature has been suggested as an explanation. This study assessed the temperature stability of two different Plasmodium lactate dehydrogenase (pLDH)- and three histidine-rich protein 2 (HRP2)-detecting RDTs. One HRP2 test proved insufficiently sensitive for assessment. After incubation at 35, 45 and 60 degrees C, two RDTs detecting pLDH showed a substantial fall in percentage test line positivity over time, which was not seen with the remaining two HRP-2-based RDTs. For the particular products studied, variability was high, with the pLDH-based RDTs being less sensitive than HRP2-based RDTs against the sample of P. falciparum used and more susceptible to heat-induced damage, but the reasons for this are unclear. The performance of malaria RDTs can be adversely affected at the temperatures to which they will be exposed when transported to, and used in, the rural tropics.

Animals↗

PubMed2006

Pyrosequencing, a high-throughput method for detecting single nucleotide polymorphisms in the dihydrofolate reductase and dihydropteroate synthetase genes of Plasmodium falciparum.

A pyrosequencing protocol was developed as a rapid and reliable method to identify the mutations of the dhfr and dhps genes of Plasmodium falciparum that are associated with antifolate resistance. The accuracy and specificity of this method were tested using six laboratory-cultured P. falciparum isolates harboring known single nucleotide polymorphisms (SNPs) in the genes dhfr (codons 50, 51, 59, 108, and 164) and dhps (codons 436, 437, 540, 581, and 613). The lowest threshold for detection of all the SNPs tested by pyrosequencing was the equivalent of two to four parasite genomes. Also, this method was highly specific for P. falciparum, as it did not amplify any DNA products from the other species of human malaria parasites. We also mixed wild-type and mutant-type parasite DNAs in various proportions to determine how pyrosequencing, restriction fragment length polymorphism (RFLP), and direct conventional sequencing (for dhfr) compared with each other in detecting different SNPs in the mixture. In general, pyrosequencing and RFLP showed comparable sensitivities in detecting most of the SNPs in dhfr except for the 164L mutation, which required at least twice the amount of DNA for pyroseqencing as for RFLP. For detecting SNPs in dhps, pyrosequencing was slightly more sensitive than RFLP and direct sequencing. Overall, pyrosequencing was faster and less expensive than either RFLP or direct sequencing. Thus, pyrosequencing is a practical alternative method that can be used in a high-throughput format for molecular surveillance of antimalarial-drug resistance.

Animals↗

PubMed2003

Adaptation of a strain of Plasmodium falciparum from Ghana to Aotus lemurinus griseimembra, A. nancymai, and A. vociferans monkeys.

A strain of Plasmodium falciparum from Ghana was adapted to Aotus lemurinus griseimembra, A. nancymai, and A. vociferans monkeys. Gametocytes in splenectomized A. nancymai were infective to Anopheles freeborni mosquitoes. Sporozoite transmission was accomplished in two splenectomized A. nancymai with prepatent periods of 22 and 25 days. The Ghana III/CDC strain of P. falciparum is susceptible to treatment with chloroquine and mefloquine.

Adaptation, Biological↗

PubMed2002

Experimental infection of Anopheles farauti with different species of Plasmodium.

Studies were conducted to determine the susceptibility of Anopheles farauti to different species and strains of Plasmodium. Mosquitoes were infected by feeding on animals or cultures infected with different strains of P. vivax, P. falciparum, P. ovale, P. coatneyi, P. gonderi, P. simiovale, P. knowlesi, and P. brasilianum. Infections of P. vivax and P. coatneyi were transmitted via sporozoites from An. farauti to monkeys. Comparative infection studies indicated that An. farauti was less susceptible to infection than An. stephensi, An. gambiae, An. freeborni, and An. dirus with the Salvador I strain of P. vivax, but more susceptible than An. stephensi and An. gambiae to infection with the coindigenous Indonesian XIX strain.

Animals↗