RIBONUCLEASE INHIBITOR FROM BOVINE BRAIN*

A ribonuclease inhibitor from bovine brain has been purified 27000-fold by affinity chromatography on Sepharose-RNase A with an overall yield of 46% (ca. 0.4 mg/kg tissue). The purified inhibitor gives a single band by SDS-gel electrophoresis. By gel filtration the molecular weight is ca. 50 000; the molecular weight of the complex with bovine pancreatic RNase A is ca. 62 000, indicative of 1:1 binding on a molar basis. The inhibition of the action of RNase A on yeast RNA by the inhibitor is noncompetitive with a K_iof 7 times 10^-10 M. The protein is very similar in its properties, including amino acid composition, to the inhibitor previously isolated from human placenta. The amount of inhibitor per g of protein in bovine brain is about one-seventh of the value for human placenta. No difference was found in the distribution of inhibitor between white and gray matter; one-tenth of the inhibitor present is bound to a brain ribonuclease which is released in active form after reaction with p-hydroxymercuribenzoate. Essentially no free neutral ribonuclease activity could be detected in brain homogenates in the absence of p-hydroxymercuribenzoate.     

The assessment and manipulation of personal diet: an undergraduate practical in human nutrition

The Department of Paediatrics at King Saud University, Riyadh, Saudi Arabia offers to medical undergraduates an optional course in nutrition and growth. This paper describes the practical experiences offered in dietary assessment and manipulation which was one component of the course, together with an assessment of its value by the students and the authors. Generally, it seemed that the component had been successful but three changes might be considered: although hand analysis of crude dietary data to determine nutrient intakes is a useful exercise, computer analysis should also be included; the principles of dietary manipulation (in effect, the principles of therapeutic dietetics) will require more emphasis; the students should make a detailed analysis of a patient's diet as well as their own. Regarding the nutrition and growth course as a whole: assessment of clinical skills would probably benefit from the same structured approach as used in the dietetic assessment; a preliminary assessment of the students' nutritional knowledge at the start of the course should be incorporated.     

SIMPLE VERSUS SOPHISTICATED MODELS OF BREATH ALCOHOL EXHALATION PROFILES

For medicolegal purposes, breath alcohol content is typicallydetermined from an end-expiratory sample. Measurements obtainedby this method necessarily underestimate the alveolar breathalcohol content, and therefore underestimate the blood alcoholcontent. We suggest and analyse an improved paradigm which usesthe entire time-series of breath alcohol measurements duringexhalation, not simply the last recorded value. We present twomathematical models for the exhaling lung, and discuss the implicationsof each for more accurate and therefore more reliable breathalcohol measurement.