Use of cell cultures as an indicator of pathogenicity of free-living amoebae

Results comparing the time needed for the development of cytopathic effects in cell cultures with that needed to cause death in mice using inocula of Naegleria and Acanthamoeba are presented. The significance of the source and concentration of the inocula is demonstrated. The use of cell cultures as an indicator of the pathogenicity of free-living amoebae is discussed.

Thyroxine metabolism in diabetic rats

The metabolism of thyroxine (T4) was determined in untreated and in insulin-treated diabetic rats. The results were compared with those obtained in a control group. Male Wistar rats weighing approximately 200 g were made diabetic by the intraperitoneal administration of streptozotocin (6.5 mg/100 g body weight) and 17 of those with blood sugar levels above 500 mg/100 ml were studied. In addition, 11 insulin-treated diabetic and 18 control rats were investigated. All the animals were injected intravenously with a tracer dose of [125I]T4 (1 μCi and 0.015 μg). After this blood samples were obtained by cardiac puncture at 16, 24, 40 and 48 h. The 24-h urinary excretion of inorganic 125iodide was also determined. The parameters of T4 metabolism were obtained by the least squares method and by an extrapolation technique. In untreated diabetic rats the fractional T4 turnover was 4.4%h, the distribution space 36.7 ml/100 g body weight, metabolic clearance 1.57 ml/100 g/h and urinary clearance 0.33 ml/100 g/h. The 24-h urinary excretion of 125iodide was 21.3 % of the injected radioactivity. Of these values the distribution space (P < 0.001) and metabolic clearance (P < 0.05) were significantly increased above those in the control animals. In insulin-treated rats all parameters were within normal values. Among these groups the serum T4 concentration was measured in 6 control, 5 untreated diabetic and 6 insulin-treated animals. The untreated diabetic animals had a significantly decreased serum T4 level but this was balanced by an enlarged distribution space so that the final hormone degradation was normal. In addition, the T4 binding activity of serum was assessed by the in vitro red cells uptake of [125I] T4 and by determining the proportion of serum free T4. Both these indices indicated a decrease in serum binding activity in the diabetic animals. The data suggest that the fall in serum T4 levels observed in the untreated diabetic rats was the result of decreased plasma binding of T4 and an increase in distribution space precipitated by lack of insulin.

Pathogenic free-living amebae (PFLA) from frozen swimming areas in Oslo, Norway

Water samples were taken from 4 frozen swimming areas in Oslo, Norway and examined for pathogenic and non-pathogenic limax amebae. All samples contained amebae and 2 of the areas yielded pathogens (Acanthamoeba castellanii). The relationship between distribution and temperature is discussed.

Detritus-Based Food Webs: Exploitation by Juvenile Chum Salmon ( Oncorhynchus keta )

Harpacticoid copepods are the principal food of chum salmon during the first critical weeks of estuarine life. Heterotrophic food sources are preferentially ingested by harpacticoids. A commercially valuable fisheries resource, usually considered to be planktivorous, is related to a detritus-based, benthically derived food web.

Primary amoebic mengingoencephalitis contracted in a thermal tributary of the Waikato River--Taupo: a case report

The case history and identification of the aetiological agent of a case of primary amoebic meningoencephalitis contracted from a natural thermal steam is presented. The diagnosis and treatment of suspected cases is discussed.

The 1968 New Zealand cases of primary amoebic meningoencephalitis--Myxomycete or Naegleria?

The 1968 New Zealand cases of primary amoebic meningoencephalitis are reviewed with reference to the identification of the aetiological organisms. Evidence is presented to show that they were Naegleria gruberi.