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Biomedical subjects

I F Cook

Publications and source records attributed to I F Cook.

14 recordsLinked to original sources
PubMed1986

Race-linked differences in serum concentrations of dapsone, monoacetyldapsone and pyrimethamine during malaria prophylaxis.

Serum concentrations of dapsone (DDS), monoacetyldapsone (MADDS), the principal acetylated metabolite of DDS, and pyrimethamine (PYR) were measured in 55 Caucasian adults (31 males, 24 females) and 159 Papua New Guinean adults (140 males, 19 females) following the oral administration of Folaprim (100mg DDS; 12.5mg PYR). Blood samples were collected at mean sampling times of eight hours after medication and 18 hours before the next weekly dose for malaria prophylaxis. Clearance of DDS and MADDS from serum were significantly faster (p less than 0.001) in Caucasians than in Papua New Guineans. Significantly lower (p less than greater 0.001) serum concentrations of PYR were found in Papua New Guineans than in Caucasians at both sampling times, an observation which may reflect differences in the bioavailability of PYR between the two racial groups. The theoretical implications of these results are that Caucasians may be more susceptible to PYR-resistant Plasmodium falciparum malaria than Papua New Guineans whilst Papua New Guineans may be more susceptible to P. vivax; malaria than Caucasians.

Adolescent↗
PubMed1985

Haematological safety of long-term malarial prophylaxis with dapsone-pyrimethamine.

There are no published haematological data on the long-term (more than one year) use of dapsone-pyrimethamine (Maloprim, Folaprim; one tablet a week) for malarial prophylaxis. In a study of 373 male Papua New Guinean soldiers who had used this combination for five years, we found no haematological abnormalities attributable to dapsone-pyrimethamine. Furthermore, the haematological parameters of these soldiers were not clinically different from those of Papua New Guinean university students who did not ingest antimalarial drugs prophylactically. In a parallel study, 9 of 159 white persons (6 children and 3 adult females) who had used dapsone-pyrimethamine prophylaxis for more than one year had haematological abnormalities attributable to the drug. Additionally, the mean leucocyte count of children aged 1-9 years who took dapsone-pyrimethamine was markedly lower--although within the normal range--than that of similarly aged children who received chloroquine for malarial prophylaxis. The appreciable incidence of haematological abnormalities observed in children during malarial prophylaxis with dapsone-pyrimethamine demonstrates the need to select a dose for this group on a weight rather than an age basis and to use a liquid formulation to facilitate the administration of the appropriate dose of this combination. Haematological monitoring of the long-term use of dapsone-pyrimethamine is recommended and a suitable monitoring regimen is suggested.

Adolescent↗
PubMed1985

Inadequate prophylaxis of malaria with dapsone-pyrimethamine.

The dapsone-pyrimethamine combination (100 mg of dapsone, 12.5 mg of pyrimethamine [Folaprim; Maloprim, one tablet a week) is considered to provide adequate prophylaxis for Plasmodium falciparum malaria, but to be inadequate for the prevention of P. vivax malaria. Field trials and case reports, however, have shown the comparable efficacy of this combination in the suppression of parasitaemias caused by both parasites. In Lae, Papua New Guinea, 12 patients with clinical signs of malaria had serum concentrations of dapsone-pyrimethamine which were consistent with appropriate weekly use of this combination. The fact that 10 of these patients had P. vivax malaria supports the hitherto unsubstantiated view that dapsone-pyrimethamine can be ineffective in suppressing parasitaemias caused by this parasite. In the two patients with P. falciparum malaria, host factors rather than parasite resistance to dapsone-pyrimethamine were implicated in the development of the parasitaemias.

Adolescent↗
PubMed1985

Herpes zoster in children following malaria.

Herpes zoster is uncommon in normal children in the 0-9 year age group. However, its incidence is markedly increased in those who are immunosuppressed. Six Papua New Guinean children under 9 years of age developed herpes zoster following an episode of malaria, due to Plasmodium falciparum or Plasmodium vivax which was treated with chloroquine. The reactivation of the varicella-zoster virus in these patients may reflect transient depression of cell-mediated immunity by these malaria parasites, possibly augmented by the chloroquine used in their treatment.

Child↗
PubMed1973

The stereochemistry of hydrogen elimination from C-7 during biosynthesis of ecdysones in insects and plants.

1. [7alpha-(3)H(1)]- and [7beta-(3)H(1)]-Cholesterol were synthesized by a modified method. 2. The stereochemistry of Delta(7)-bond formation during ecdysone and ecdysterone biosynthesis in the insect, Calliphora erythrocephala and the plants, Taxus baccata and Polypodium vulgare was investigated by using [4-(14)C,7alpha-(3)H(1)]cholesterol and [4-(14)C,7beta-(3)H(1)]cholesterol. 3. In each case, the 7beta hydrogen was stereospecifically eliminated. 4. The possible significance of the results is discussed in relation to double-bond formation in other systems and the stage at which the Delta(7) bond is introduced during ecdysone biosynthesis.

Animals↗