R. Knight

Fine structural changes at Entamoeba histolytica rabbit kidney cell (RK 13) interface.

When bacteria-free trophozoites of Entamoeba histolytica were added to a monolayer of rabbit kidney cells, cellular injury occurred at the sites of contact. Changes appeared within the cell cytoplasm before there was any generalized cell membrane damage. At some points of contact there was apparent fusion of amoebic and cell cytoplasm. Electron-dense bodies, here interpreted as liposomes, were present in the amoebic cytoplasm and beneath the surface membrane. No surface lysosomes were seen. Various modes of cell damage and enzyme transfer from amoeba to cell are suggested, together with the possibility that cytopathic amoebae are infected with virus particles.

Dietary factors affecting the pathogenicity of Entamoeba histolytica in rats.

Abstract Weanling rats given protein deficient diets for 2 to 4 weeks and then infected intracaecally with Entamoeba histolytica trophozoites showed a greater susceptibility to infection compared with controls. The proportion of infected animals that developed caecal ulceration was also increased. Supplementation of the low protein diet with extra carbohydrate produced an even greater infection rate but the likelihood of caecal ulceration was lower. No relationship between amoebic infection and the bacterial flora or pH of the caecum was noted, however the redox potential was lower in those animals that developed ulceration. The possible mechanisms involved are discussed together with the relevance of these findings to human amoebiasis.

The direct antiglobulin test and immunoconglutinin titres in patients with malaria

Abstract The erythrocytes of 13 23 patients with clinical malaria were agglutinated at some time by anti-non-gamma globulin sera in contrast to 1 23 samples from control normal persons. Samples from patients and controls were handled in parallel from the moment of sampling onwards. The immunoconglutinin titre of the serum was raised in 6 10 patients with clinical malaria.

The mechanism of anaemia in kala-azar a study of 2 patients

Abstract Two patients with proved visceral leishmaniasis were studied with radio-iron 59Fe and radio-chromium 51Cr respectively, in an attempt to elucidate some of the mechanisms producing anaemia in this disease. The red cell life span was shown to be greatly reduced, with sequestration and probable haemolysis occurring in the spleen. The ferrokinetic studies suggested a mild degree of ineffective erythropoiesis. Blood volume determinations were normal.

The interaction between Entamoeba histolytica and Schistosoma mansoni infections in mice.

Abstract A synergistic relationship between caecal amoebiasis and S. mansoni infections has been demonstrated in the mouse. The interaction affected both the infectivity of an E. histolytica inoculum and also the likelihood of amoebic tissue invasion. There was some correlation with worm load. Prepatent schistosome infections were apparently without effect but animals with unisexual infections were somewhat more susceptible than controls. Possible mechanisms include intramucosal tissue damage produced by schistosome ova and an altered immunological responsiveness.

Some applications of radiochromium 51Cr in assessing the value of therapeutic regimes and the effects of crises in haemoglobinopathic states.

Abstract 12 patients suffering from various haemoglobinopathies were studied by tagging their red cells with radiochromium 51 Cr. Shortened red cell survival was shown in HbC disease, HbSC disease and HbS thalassaemia and sickle cell anaemia; cell destruction was mainly in the liver in the last of these and in the spleen in HbC and HbSC disease. The dynamics of sickling crises were shown to consist principally of temporary red cell sequestration in the spleen. Measurements were made on the effects of sodium bicarbonate and phenothiazines on red cell survival, on the severity of crises and on the deleterious effects of pyrexia: no beneficial effect on erythrocyte life span was demonstrated. Attention is drawn to the diuresis and possible dehydration that can follow administration of sodium bicarbonate in sicklaemic patients; this might be a factor in precipitating a crisis. Administration of desmethylchlorpromazine was followed by diminution of bone pain, improvement in wellbeing and development of a feeling of warmth in the extremities of some patients. The vasodilator effect of the drug was thought to be responsible for this and is considered worthy of further investigation in sicklaemic states.