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Biomedical subjects

S R Mack

Publications and source records attributed to S R Mack.

9 recordsLinked to original sources
PubMed1979

Effects of 2,4-dinitrophenol on trichomonads and Entamoeba invadens.

1. 2,4-Dinitrophenol (2,4-DNP) in substrate level concentrations (200 microM-1 mM) temporarily inhibits H2 production by Tritrichomonas foetus and Trichomonas vaginalis as well as the accumulation of metronidazole, dependent on its reduction by the two trichomonad species and by Entamoeba invadens. 2. 2,4-DNP competes for the reducing equivalents which are necessary for H2 production or for the reduction of metronidazole, thereby inhibiting these processes. 2,4-DNP is reduced to 2-amino, 4-nitrophenol. 3. 2,4-DNP in concentrations up to 800 microM has no effect on the uptake of O2 by these organisms. 4. 2,4-DNP has some toxicity for T. foetus.

2,4-Dinitrophenol↗
PubMed1979

Hemolymph of Anopheles stephensi from uninfected and Plasmodium berghei-infected mosquitoes. 2. Free amino acids.

Determinations were made of free amino acids in hemolymph collected from adult female Anopheles stephensi mosquitoes. The hemolymph first was fractionated by extraction and precipitation procedures, after which qualitative determinations of free amino acids were made by high voltage thin layer electrophoresis, and thin layer chromatography. Subsequent quantitative determinations were made with an automatic amino acid analyzer. The concentration of total free amino acids in the hemolymph rose 60--70% after the mosquito took a blood meal, and remained relatively constant thereafter. When mosquitoes took a blood meal infected with the rodent malaria parasite Plasmodium berghei, the rise in total free amino acids was only 15--25%. The chief differences that occurred with individual free amino acids was that infected mosquitoes had greater increases in arginine, greater decreases in valine and histidine, and a total loss of detectable methionine.

Amino Acids↗
PubMed1979

Hemolymph of Anopheles stephensi from noninfected and Plasmodium berghei-infected mosquitoes. 3. Carbohydrates.

Determinations were made of carbohydrates in hemolymph collected from adult female mosquitoes (Anopheles stephensi). First the hemolymph was fractionated by extraction and precipitation procedures, after which qualitative and quantitative determinations of carbohydrates were made by thin layer chromatography. The most abundant sugars found in the hemolymph were glucose and trehalose, though maltose, glucuronic acid, and inositol could be found after the mosquitoes took blood meals. After the mosquitoes ingested a noninfected blood meal, their hemolymph sugar levels rose almost 4-fold. There was less of an increase following a blood meal infected with the rodent malaria parasite, Plasmodium berghei. Depletion of sugars in the hemolymph of infected mosquitoes may result from direct utilization of sugar by the malaria parasite developing within the mosquito.

Animals↗
PubMed1978

Hemolymph of Anopheles stephensi from noninfected and Plasmodium berghei-infected mosquitoes. 1. Collection procedure and physical characteristics.

Hemolymph was collected from adult female Anopheles stephensi by centrifugation of incised mosquitoes. Approximately 0.1 muliter was collected from each recently emerged mosquito, although smaller amounts were recovered with increasing age of the mosquito. Determinations were made of the pH, osmotic pressure, and specific gravity of this hemolymph at various times during the life of the adult mosquito. The values obtained were within the ranges found for other insects. Hemolymph collected from mosquitoes fed on hamsters infected with Plasmodium berghei had different values than hemolymph from mosquitoes fed on noninfected hamsters. This probably was due to differences between the quality of these 2 types of blood meals, rather than to the direct effects of the malaria parasite on the infected mosquito itself.

Aging↗
PubMed1977

In vitro cultivation of the sporogonic stages of Plasmodium: a review.

Complete and continuous in vitro development of the sporogonic stages of the malarial parasite has not yet been accomplished, although success with erythrocytic stages (falciparum malaria) and exoerythrocytic stages (avian malaria) has been achieved. This lag in progress appears to be due to several inherent differences between sporogony and these other sequences of development. The Trager-Jensen system for in vitro development of erythrocytic stages of Plasmodium falciparum results in the formation of gametocytes, although these gametocytes have not yet been shown to be functionally mature. An improvement in culture conditions, leading to the formation of infective gametocytes, would be an important advance. Culture systems for the transformation of gametocytes to ookinetes have been described, but whether this can be easily accomplished for falciparum malaria remains to be determined. The subsequent stages of sporogony, leading from oocyst differentiation to the formation of mature, infective sporozoites, have been successfully grown in short-term in vitro cultures. The entire developmental sequence, however, has been obtained only by overlapping successive stages in different cultures. This has established that all phases of sporogony are inherently capable of being supported in vitro. Further improvements may come through a better understanding of appropriate culture conditions.

Animals↗