The effects of potassium, 5-hydroxytryptamine, adrenocorticotrophin and angiotensin II on the concentration of adenosine 3′:5′-cyclic monophosphate in suspensions of dispersed rat adrenal zona glomerulosa and zona fasciculata cells

Dispersed rat adrenal cells prepared from both the capsule and the decapsulated gland were used to investigate the effects on cyclic AMP accumulation of known stimuli of steroidogenesis [ACTH (adrenocorticotrophin), angiotensin II, K(+) ions and 5-hydroxytryptamine]. Since glomerulosa-cell preparations from capsular strippings are normally contaminated with a proportion of fasciculata cells, cells purified by fractionation on a bovine serum albumin gradient were also used. The results showed that: (1) ACTH and angiotensin II stimulated cyclic AMP accumulation in both fractionated and unfractionated zona fasciculata cells; (2) 5-hydroxytryptamine and an increased extracellular K(+) concentration (from 3.6 to 8.4mm) had no effect on cyclic AMP concentrations in fasciculata cell preparations; (3) the addition of ACTH, angiotensin II, 5-hydroxytryptamine or K(+) to the incubation medium resulted in increased cyclic AMP concentrations in unpurified zona glomerulosa cell preparations; (4) fractionation and hence the virtual elimination of fasciculata contamination, did not affect the response to 5-hydroxytryptamine and increased K(+) concentration. However, the responses to ACTH and angiotensin II were markedly lowered but not abolished. These results strongly suggest a link between cyclic AMP production and steroidogenesis in the zone of the adrenal gland that specifically secretes aldosterone. All four agents used stimulated both steroid output and cyclic AMP accumulation. However, at certain doses of 5-hydroxytryptamine, K(+) and angiotensin II the significant increases in corticosterone output were not accompanied by measurable increases in cyclic AMP accumulation.     

Influence of the Maize Dwarf Mosaic Virns and Simazine upon the Buffer Soluble Proteins and Catalase Activity of a Virus-susceptible and a Virus-tolerant Variety of Zea mays

Inbred corn varieties differing in their tolerance to the maize dwarf mosaic virus infection also differ in varietal character and host response to simazine. Oh 7B, a tolerant cv., has less total soluble and globulin proteins than the sensitive variety, H 55, but more Kjeldahl nitrogen, albumin protein and a doubling of catalase activity. Virus inoculation in Oh 7B causes a reduction in all three protein fractions, Kjeldahl nitrogen and catalase activity. Deleterious virus-simazine interaction does not occur with either variety and the observed varietal and host response differences in protein may account for the conflicting reports of other workers.     

Glucose Tolerance and Serum Insulin in Identical Twins of Diabetics

Glucose tolerance with serum insulin assay has been carried out in 24 apparently unaffected identical twins of diabetics. Glucose values were significantly higher and insulin values significantly lower than in control subjects, but there was considerable individual variation and in half the cases glucose tolerance was normal. There was no case of increased insulin response. In these twins glucose tolerance and insulin response were not correlated with weight, family history of diabetes, age at diagnosis of diabetes in the affected twin, time since that diagnosis, nor with age at testing the unaffected twin. On retesting 12 of the twins after two years no significant differences were found from the first testing.We conclude that not all these twins are likely to develop diabetes, that the assumption that identical twins of diabetics are necessarily “prediabetic” is probably erroneous, and that factors other than genetic ones are important in the aetiology of diabetes.     

Hemagglutinating Property of Haemophilus aegyptius

Extracts possessing the capacity to hemagglutinate normal human erythrocytes were recovered from Haemophilus aegyptius by treatment with either diethylene glycol or acetone. Antisera prepared against these extracts or the unextracted bacterial cell inhibited hemagglutination by homologous and heterologous antigens. Microgel diffusions indicated the presence of identical components in each extract as expressed by lines of identity between antisera to each fraction. The hemagglutinin was identified as a lipopolysaccharide, 42% lipid and 57% carbohydrate. The determination of 6% phosphorus in the lipid fraction identified it as containing phospholipid.     

DNA base composition of Microcyclus species and organisms of similar morphology

Summary From studies of the DNA base composition of Microcyclus species, it is concluded that the genus is to be regarded as a taxonomically heterogeneous group. This agrees with morphological observations of the different species.     

The interaction of aflatoxins with purines and purine nucleosides

From measurements of thermal hyperchromicity and the behaviour of an aflatoxin-DNA mixture on a Sephadex column it was concluded that aflatoxin B(1) is capable of weak binding to single-stranded DNA. The interactions of the aflatoxins (B(1), G(1) and G(2)) with nucleosides result in difference spectra and suggest that the purine bases and the amino group play a role in the binding of all the aflatoxins to DNA.