Introduction to the age-related diagnosis (ARD) index: an age at presentation related index for diagnostic use.

Development and, therefore, age is important in paediatrics. Diagnostically useful data from this journal has been related to age and organized to form an age-related diagnostic (ARD) index. The ARD index is designed for non-expert clinical and laboratory workers to use in the early phases of diagnosis and as an addition to existing diagnostic schemes. Entry to the index is from the age at clinical presentation. Each entry is a sequence starting with clinical and laboratory presentations, clinical course, laboratory key investigations and finally diagnosis with volume and page numbers of the original article, the primary source. Within age groups, entries are grouped by diagnoses with the commonest diagnosis first; this has the effect of roughly but not precisely grouping similar clinical and laboratory findings.

Soluble rat adipocyte phosphatidate phosphatase activity: characterization and effects of fasting and various lipids.

Phosphatidate phosphatase (phosphatidate phosphohydrolase, EC 3.1.3.4) was present at very high specific activity in the soluble fraction of isolated rat adipocytes. Using phosphatidate in aqueous dispersion 90% of its hydrolysis depended on the presence of Mg2+. Mg2+ appeared to almost saturate the enzyme at 20-40 mM with no indication of an optimum. The substrate concentration was optimum at 1.2 mM and the pH at 6.8. Initial rates were linear for only 4-5 min at optimum conditions. Increasing inhibition occurred at high phosphatidate concentrations. At optimum conditions acid or alkaline phosphatase activity was not measurable. The Mg2+-dependent activity was enhanced by 3-sn-phophatidylcholine and inhibited by albumin, 3-sn-phosphatidyletanolamine, 3-sn-phosphatidylinositol, diacylglycerol, oleoyl-CoA, and oleate. Oleoyl-CoA was the most potent "effector". Fasting for 24, 48 and 72 h decreased the activity both relative to protein and to DNA. The activity thus decreased to about one-third of that of the fed rat during 72 h of fasting. The effects of Mg2+, various lipids, and fasting may indicate that some form of control of glyceride synthesis can be exerted through the soluble phosphatidate phosphatase.