Isolation and translation of elastin mRNA from chick aorta.

mRNA was isolated from 15-day chick embryo aortae by digestion of the tissue at 40° with Proteinase K in 1% sodium dodecyl sulfate followed by chromatography on oligo(dT)-cellulose columns. The mRNA was translated using a reticulocyte lysate system and the tropoelastin immunoprecipitated using a specific antiserum prepared against insoluble elastin. The precipitated product was characterized by polyacrylamide gel electrophoresis and a major peak corresponding to a molecular weight of approximately 70,000 daltons was observed. No higher molecular weight product was observed.     

Direct Evidence of an Elongation Factor-Tu/Ts·GTP·Aminoacyl-tRNA Quaternary Complex

During protein synthesis, elongation factor-Tu (EF-Tu) bound to GTP chaperones the entry of aminoacyl-tRNA (aa-tRNA) into actively translating ribosomes. In so doing, EF-Tu increases the rate and fidelity of the translation mechanism. Recent evidence suggests that EF-Ts, the guanosine nucleotide exchange factor for EF-Tu, directly accelerates both the formation and dissociation of the EF-Tu-GTP-Phe-tRNA^Phe ternary complex (Burnett, B. J., Altman, R. B., Ferrao, R., Alejo, J. L., Kaur, N., Kanji, J., and Blanchard, S. C. (2013) J. Biol. Chem. 288, 13917–13928). A central feature of this model is the existence of a quaternary complex of EF-Tu/Ts·GTP·aa-tRNA^aa. Here, through comparative investigations of phenylalanyl, methionyl, and arginyl ternary complexes, and the development of a strategy to monitor their formation and decay using fluorescence resonance energy transfer, we reveal the generality of this newly described EF-Ts function and the first direct evidence of the transient quaternary complex species. These findings suggest that EF-Ts may regulate ternary complex abundance in the cell through mechanisms that are distinct from its guanosine nucleotide exchange factor functions.     

Regression Models for Clinical Trials with Correlated Categorical Responses

Regression models for correlated categorical data are presented in which the covariance is a function of measured effects. The regression and covariance parameters are estimated by extended least square methods. A numerical example of a clinical trial comparing two antiemetic treatment regimes for patients receiving chemotherapy is given to illustrate the approach.     

NMR in vitro measurements: a quality control study of the RADX table-top spectrometer

A series of experiments was performed to evaluate the accuracy and reproducibility of relaxation values obtained by two RADX table-top spectrometers operating at 5 MHz (R5) and 10 MHz (R10) respectively. The output (T1, T2, and proton content) of each machine was compared (for tissue specimens and paramagnetic solutions) to reference spectrometers. In the range of tissue T1's, R5 overestimates T1 by approx. 10% and R10 underestimates by approx. 23%. For tissue specimens, the T2 output of both machines is within 3% of the reference facility. Proton content values correlate well with the % wet weight of tissues (y = .46x + 24, r = .85) but accuracy deteriorates badly if tissue T1 greater than 400 msec or T2 greater than 300 msec. The output of both machines is accurate and reproducible within 5% over the range of tissue relaxation values (biological fluids excluded).     

Distribution of amiloride-sensitive sodium channels in the oral cavity of the hamster

The distribution of amiloride-sensitive sodium channels (ASSCs) in taste buds isolated from the oral cavity of hamsters was assessed by patch clamp recording. In contrast to the case for rats, taste cells from the fungiform, foliate and vallate papillae and from the soft palate all contain functional ASSCs. The differential distribution of ASSCs between the hamster and the rat may be important for understanding the physiology underlying the differing behavioral responses of these species to sodium salts.      

Base Composition and Hybridization Studies of the Three Double-Stranded RNA Segments of Bacteriophage φ6

The three double-stranded ribonucleic acid (dsRNA) segments of the bacteriophage phi6 were isolated and shown to have similar melting temperatures and base compositions. RNA:RNA hybridization experiments with the isolated segments eliminate the possibility that the two smaller dsRNA segments arise from a cleavage of the large dsRNA segment. The two smaller RNA segments reanneal rapidly even at low temperatures; in contrast, the large dsRNA reannealed only at higher temperatures. Evidence is also presented which suggests that the dsRNAs may contain a short single-stranded RNA tail.