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RNA synthesis in the venom glands of Crotalus durissus terrificus was stimulated by the manual extraction of the venom (milking). RNA was extracted from venom glands activated by milking and fractionated by centrifugation through sucrose density gradients. Template activity for protein synthesis and base composition of the RNA fractions were studied. RNA fractions that sediment between 18S and 4S had the highest template activity. The base composition analysis indicated that the 28S and 18S rRNA have a C+G content of 65.4 and 58% respectively. The `melting' temperature (Tm) of DNA in 0.15m-NaCl–0.015m-trisodium citrate, pH7.0, was 85°C, corresponding to a C+G content of 38%. The base ratio of the RNA fractions that showed a high template activity was intermediate between that of rRNA and homologous DNA. The possible role of these fractions in the synthesis of the two main toxins (crotoxin and crotamine) of the South American rattlesnake's venom is discussed.

Absolute photon-flux measurements in the vacuum ultraviolet have been extended to short wavelengths by use of rare-gas ionization chambers. The technique involves the measurement of the ion current as a function of the gas pressure in the ion chamber. The true value of the ion current, and hence the absolute photon flux, is obtained by extrapolating the ion current to zero gas pressure. Examples are given at 162 and 266 Å. The short-wavelength limit is determined only by the sensitivity of the current-measuring apparatus and by our present knowledge of the photoionization processes that occur in the rare gases.

The precise determination of biparietal diameter (BPD) of fetal heads in uterois of considerable value in gestation age prediction. The method most widely employed was evolved by Campbell (1968). In essence this consists of longitudinal B-scans to locate the fetal head and to measurethe angle a lateral flexion. Transverse B-scans are next performed with the scanning plane preset at angle a When the ultrasonic beam crosses the largest diameter of the fetal head bisected by a midline, the A-scan permits the measurement of BPD.The BPD is usually presented digitally, the measurement being made by means of an electronic caliper such as that described by Bowley, Christie and Nicol (1972). This caliper has two bright spots which can be superimposed on the leading edges the A-scan trace, one corresponding to the outer proximal skull surface and the second to the inner distal skull surface. The calibration of the apparatus is made so that marker separation is equal to echo separation in millimetres.We have found that in a significant number cases the method can fail. There are various reasons for this. The orientation of the fetal head may be such that the angle a is in the first instance wrongly determined. Secondly if the head is mobile the value of a obtained from a longitudinal scan may unsuitable by the time the transverse scans are performed.

A single intravenous injection of L-[3H]fucose, a specific glycoprotein precursor, was given to young 35–45 g rats which were sacrificed at times varying between 2 min and 30 h later. Radioautography of over 50 cell types, including renewing and nonrenewing cells, was carried out for light and electron microscope study. At early time intervals (2–10 min after injection), light microscope radioautography showed a reaction over nearly all cells investigated in the form of a discrete clump of silver grains over the Golgi region. This reaction varied in intensity and duration from cell type to cell type. Electron microscope radioautographs of duodenal villus columnar cells and kidney proximal and distal tubule cells at early time intervals revealed that the silver grains were restricted to Golgi saccules. These observations are interpreted to mean that glycoproteins undergoing synthesis incorporate fucose in the saccules of the Golgi apparatus. Since fucose occurs as a terminal residue in the carbohydrate side chains of glycoproteins, the Golgi saccules would be the site of completion of synthesis of these side chains. At later time intervals, light and electron microscope radioautography demonstrated a decrease in the reaction intensity of the Golgi region, while reactions appeared over other parts of the cells: lysosomes, secretory material, and plasma membrane. The intensity of the reactions observed over the plasma membrane varied considerably in various cell types; furthermore the reactions were restricted to the apical surface in some types, but extended to the whole surface in others. Since the plasma membrane is covered by a "cell coat" composed of the carbohydrate-rich portions of membrane glycoproteins, it is concluded that newly formed glycoproteins, after acquiring fucose in the Golgi apparatus, migrate to the cell surface to contribute to the cell coat. This contribution implies turnover of cell coat glycoproteins, at least in nonrenewing cell types, such as those of kidney tubules. In the young cells of renewing populations, e.g. those of gastro-intestinal epithelia, the new glycoproteins seem to contribute to the growth as well as the turnover of the cell coat. The differences in reactivity among different cell types and cell surfaces imply considerable differences in the turnover rates of the cell coats.

Dr. David Hirschfeld, Junior Assistant Resident in Medicine, Jewish Hospital of St. Louis; and Assistant in Medicine, Washington University School of Medicine: A 62-year-old white woman was referred to this hospital in October 1968 for evaluation of Paget's disease, which was initially diagnosed by x-ray film in 1961 during intravenous pyelographic studies. The patient remained asymptomatic until 1963 when pain in the left side of the pelvis and left upper leg was noted. These symptoms have persisted with variable intensity to the present time. In 1967 the patient was subsequently seen at another institution and on two occasions received intravenously administered radioactive phosphorus therapy (sodium phosphate P32) for the complaints. In each instance, the administration of the isotope was apparently associated with symptomatic improvement of the bone pain. The patient denied any history of bone fracture or renal calculi.Physical examination revealed a middle-aged woman in no acute distress. Pulse

The results are reported of a comprehensive experimental investigation of the tensile behavior of twisted continuous- filament glass yarns. Existing theoretical treatments are reviewed and their compatability with the experimental results are examined. A physical model is proposed, based on a wrapped-ribbon twist geometry, which predicts both tensile modulus and tenacity of glass yarns as a function of the twist angle. The effect of filament bending strain on yarn tenacity has been included in the analysis. Excellent agreement between the model and the experimental results is shown.

In this paper a method for designing control systems with random parameters and random initial state is presented. The observed signal available for feedback is a function of the state and system parameters corrupted by additive white Gaussian noise with zero mean. The proposed control consists of an open-loop term, which is the optimal control for the parameters and initial state equal to their mean values, plus a feedback correction term. The feedback correction term is a linear function of the estimated values of the deviation in initial state and system parameters from their mean values. The control tends to the optimally sensitive control when the measurement noise tends to zero, and the feedback correction tends to zero when the measurement noise tends to infinity. A numerical experiment with a simplified model for nuclear reactor control shows that in spite of fairly large measurement noise, significant improvement in performance can be achieved using the proposed control compared to open-loop control.

It has been estimated that sudden unexpected cardiac arrest occurs 10,000 times annually in this country,1 although resuscitative measures are not undertaken nearly so frequently. However, resuscitation of an arrested heart, whether it is caused by cardiac standstill or ventricular fibrillation, is a common daily occurrence, and so many really dramatic recoveries have been reported in both medical and lay press in recent months that it is no longer of medical importance to add another case to the growing list unless the events were most unusual.2-11We feel that this case is of unusual medical interest because cardiac resuscitation by manual compression was performed 90 minutes after apparent clinical death due to cardiac arrest, when other methods of revival had failed. The patient made a complete recovery without any cardiac or neurologic sequelae and is perfectly normal at the time of this report, which is several months after

Once cystic fibrosis of the pancreas had been recognized as a clinical and pathological entity, histological alteration of the liver was found to be a common feature of the total process1-3 with qualitative and quantitative differences. The basic liver lesions described have included liver-cell atrophy, fatty metamorphosis, periportal fibrosis, and proliferation of the bile ducts, often distended by obstructing bile plugs.1-7 In certain more advanced cases, a focal biliary cirrhosis was found, and this has been considered by most to be due to the focal obstructive lesions resulting from the altered and inspissated bile-containing mucus plugs in the dilated terminal radicles.1-3,5,7-13*This report is a review of the clinical records and postmortem material of 198 autopsied cases of cystic fibrosis of the pancreas. An attempt is made to define the liver changes, to indicate the pathogenesis, and to relate their changes noted to the total clinical picture