A simplified method for study of RNA conformation--reaction of formylmethionine transfer RNA with [14C]methylamine-bisulfite

A new chemical method for radioactive labeling of single-stranded regions of RNA has been used to probe the three-dimensional structure of E. coli tRNA(fMet) in solution. The procedure involves conversion of cytosine residues to N(4)-[(14)C]methylcytosines by treatment with (14)CH(3)NH(2) and sodium bisulfite at pH7. Ribonuclease digestion of the modified tRNA produces (14)C-labeled oligonucleotides which comigrate with the corresponding unlabeled oligonucleotides, facilitating structural analysis. By this procedure, E. coli tRNA(fMet) has been found to contain only six reactive cytosines: C(1), C(16), C(17), C(35), C(75) and C(76). In addition, slow reaction at C(m) (33) was observed. These results are in excellent agreement with previously reported data on the sites of exposed cytosine residues in tRNA(fMet) obtained by two other chemical methods. The methylamine-bisulfite procedure is recommended for studying the ordered structure of more complex polyribonucleotides such as viral and ribosomal RNAs.

WHO international pilot study of schizophrenia

The results are described of a transcultural psychiatric study of schizophrenia undertaken by WHO in nine countries. The study proved that such a collaboration was feasible, that it was possible to develop research procedures for international use, and that similar types of schizophrenia could be found in each of the countries involved. One thousand two hundred and two patients were studied and over 2 million items of information obtained.

Simple model for the calculation of the flux of solar radiation through the atmosphere

The flux of solar radiation through a model atmosphere composed of n homogeneous layers and a ground surface is represented by 2(n + 1) linear simultaneous equations. The system is solved explicitly for the albedo and for the radiation reaching the ground as a function of the vertically incident radiation and known or assumed reflection and transmission coefficients for each of the n layers and ground surface. Inasmuch as the only distinction among any of the layers resides in the transmission and reflection coefficients assigned to each, the model may be used for any combination of cloud and cloud-free layers. Sample calculations are made for the case of n = 7 for a wide variety of cloud states in order to illustrate the properties of the system. The principal virtue of the model lies in its simplicity and in the fact that explicit solutions are obtained for the total radiation reaching the ground and reflected to space. Since direct observations of both of these parameters are now available on a routi e ba is, the model offers the opportunity of determining the transmission and reflection statistics of any individual cloud type by a suitable least-squares procedure.

Compartmentation of the jugular foramen

✓ The radiographic anatomy of the jugular foramen is described. Normal variations in size and configuration are discussed and principal pathological configurations listed. The radiographic features of complete separation of the jugular foramen into separate neural and vascular components are presented.

Suppression of food intake with intragastric loading: relation to natural feeding cycle

Rats were infused through chronically implanted intragastric tubes with 100 percent of their normal total daily food intake. The infusion was given either continuously over 24 hours or divided into discrete meals programed to simulate the rats' natural eating pattern. The same diet was also available for consumption by mouth. In neither case did the animals completely stop eating. During slow infusions excessive consumption ranged from 30 to 50 percent. During simulated meal infusion of the same total quantity of diet, they compensated far better, overeating by only 2 to 18 percent. Periodic filling of the stomach between scheduled meals was no more effective than a continuous slow infusion. Therefore, factors related to the natural feeding cycle make a significant contribution to the effectiveness of food in maintaining satiety and controlling food intake.