The soil amoebae Acanthamoeba causes Acanthamoeba keratitis, a severe sight-threatening infection of the eye and the almost universally fatal granulomatous amoebic encephalitis. More effective treatments are required. Sterol biosynthesis has been effectively targeted in numerous fungi using azole compounds that inhibit the cytochrome P450 enzyme sterol 14α-demethylase. Herein, using Gas Chromatography Mass Spectrometry (GCMS), we demonstrate that the major sterol of Acanthamoeba castellanii is ergosterol and identify novel putative precursors and intermediate sterols in its production. Unlike previously reported, we find no evidence of 7-dehydrostigmasterol or any other phytosterol in Acanthamoeba. Of five azoles tested, we demonstrate that tioconazole and voriconazole have the greatest overall inhibition for all isolates of Acanthamoeba castellanii and Acanthamoeba polyphaga tested. While miconazole and sulconazole have intermediate activity econazole is least effective. Through GCMS, we demonstrate that voriconazole inhibits 14α-demethylase as treatment inhibits the production of ergosterol, but results in the accumulation of the lanosterol substrate. These data provide the most complete description of sterol metabolism in Acanthamoeba, provide a putative framework for their further study and validate 14α-demethylase as the target for azoles in Acanthamoeba.

1. The vitamin C in the dietary of an institution was largely destroyed by the methods of cooking and distribution.2. Some 50 mg. of ascorbic acid per head per day were required to be added to the diet to produce an optimum excretion level.3. Large doses of ascorbic acid were given to a group of adolescents in the institution over a period of several months. A record was kept of the incidences of infectious diseases in this treated group and in the remainder (controls). The following conclusions were reached:(a) The incidences of common cold and tonsillitis were the same in the two groups.(b) The average duration of illness due to the common cold was the same in the two groups.(c) The duration of illness of tonsillitis was longer in the control group than in the test group.(d) Cases of rheumatic fever and pneumonia occurred in the control group but no case of either disease occurred in the test group.

Summary1. Gastro-enteritis caused by certain varieties of Bact. coli is a highly infectious disease among babies, and it has been suspected that the infectivity is associated, partly at least, with the very large numbers of pathogens excreted in the faeces. Very large numbers were found in the faeces, but large numbers of pathogens were also found in dysentery, salmonella food-poisoning and in some cases of paratyphoid fever.In cases of gastro-enteritis the dilution of faeces containing 5 to 50 pathogenic Bact. coli per ml. was usually 10−8; in Sonne dysentery and salmonella food-poisoning the corresponding dilution was 10−6. It is doubtful if even this difference can account for the differences in infectivity.2. When normal Bact. coli outnumber pathogenic Bact. coli, shigellae or salmonellae by as little as 10: 1 it is difficult to identify the pathogens unless a selective culture medium can be used.3. Ordinary nutrient broth is generally able to act as an enrichment medium for the isolation of pathogens from faeces.

No abstract

Salmonella typhi or S. paratyphi B were found in very large numbers in the faeces of enteric carriers. Of twenty-four carriers, four were found negative by the fullest examination. Of the twenty found positive almost all harboured many millions of bacilli per gram of faeces.A minute inoculum of one drop (1/50 ml.) of a 1:1000 dilution of faeces on a culture plate only rarely failed to reveal all the positives without the use of an ‘enrichment’ medium and the result of such a procedure was a culture plate with virtually a pure culture of the pathogen.I am grateful to the Medical Superintendents of the Mental Hospitals at Cardiff, Bridgend and Denbigh, and the Medical Officer of Health for Brecon for submitting specimens for examination.