Tumor necrosis factor alpha: activity dependent expression and promotion of cortical column sleep in rats.

Cortical surface evoked potentials (SEPs) are larger during sleep and characterize a sleep-like state in cortical columns. Since tumor necrosis factor alpha (TNF) may be involved in sleep regulation and is produced as a consequence of waking activity, we tested the hypothesis that direct application of TNF to the cortex will induce a sleep-like state within cortical columns and enhance SEP amplitudes. We found that microinjection of TNF onto the surface of the rat somatosensory cortex enhanced whisker stimulation-induced SEP amplitude relative to a control heat-inactivated TNF microinjection. We also determined if whisker stimulation enhanced endogenous TNF expression. TNF immunoreactivity (IR) was visualized after 2 h of deflection of a single whisker on each side. The number of TNF-IR cells increased in layers II-IV of the activated somatosensory barrel column. In two separate studies, unilateral deflection of multiple whiskers for 2 h increased the number of TNF-IR cells in layers II-V in columns that also exhibited enhanced cellular ongogene (Fos-IR). TNF-IR also colocalized with NeuN-IR suggesting that TNF expression was in neurons. Collectively these data are consistent with the hypotheses that TNF is produced in response to neural activity and in turn enhances the probability of a local sleep-like state as determined by increases in SEP amplitudes.

Real-time spatial compound imaging: application to breast, vascular, and musculoskeletal ultrasound.

Real-time spatial compound imaging (SonoCT) is an ultrasound technique that uses electronic beam steering of a transducer array to rapidly acquire several (three to nine) overlapping scans of an object from different view angles. These single-angle scans are averaged to form a multiangle compound image that is updated in real time with each subsequent scan. Compound imaging shows improved image quality compared with conventional ultrasound, primarily because of reduction of speckle, clutter, and other acoustic artifacts. Early clinical experience suggests that real-time spatial compound imaging can provide improved contrast resolution and tissue differentiation that is beneficial for imaging the breast, peripheral blood vessels, and musculoskeletal injuries. Future development of real-time spatial compound imaging will help address the bulk of general imaging applications by extending this technology to curved array transducers, tissue harmonics, panoramic imaging, and three-dimensional sonography.

Extended field-of-view ultrasound.

When ultrasound became a clinical reality in the 1970s, extended field of view was the only form of imaging available because all ultrasound images were created with articulated arm scanners that encompassed the area of interest in its entirety. With the advent of high-quality real-time imaging in the 1980s, the extended field of view was lost, and with it went an important diagnostic component as well as an important means of communicating diagnostic findings to referring clinicians. Through the magic of computer technology, extended field of view imaging is back! Extended field of view images can now be created very easily and conveniently, in real time. The convenience and accuracy of real-time imaging is maintained while important anatomical perspectives are added. This article reviews the status of real-time extended field of view sonography. The technical details as well as the clinical relevance of this method are summarized. The day-to-day clinical utility of extended field of view imaging is liberally illustrated.

Yeast serine isoacceptor tRNAs: variations of their content as a function of growth conditions and primary structure of the minor tRNA(Ser)GCU.

The primary structure of Saccharomyces cerevisiae tRNA(Ser)GCU is presented (EMBL database accession No. X74268 S. cerevisiae tRNA-Ser). In addition, quantitation of the relative amounts of serine isoaccepting tRNAs in yeast grown on different media showed that the minor tRNA(Ser)GCU decreased while the major tRNA(Ser)AGA increased as the growth rate and the cellular protein content increased. The minor species, tRNA(Ser)CGA and tRNA(Ser)UGA, were not separated by our gel system, however, taken together they appeared to vary in the same way as tRNA(Ser)GCU. These data suggest a growth rate dependence of yeast tRNAs similar to that previously described for E. coli tRNAs.

A very poorly expressed tRNA(Ser) is highly concentrated together with replication primer initiator tRNA(Met) in the yeast Ty1 virus-like particles.

The analysis of the tRNAs associated to the virus-like particles produced by the Ty1 element revealed the specific packaging of three major tRNA species, in about equal amounts: the replication primer initiator tRNA(Met), the tRNA(Ser)AGA and a tRNA undetected until now as an expressed species in yeast. The latter tRNA is coded by the already described tDNA(Ser)GCT. This tRNA is enriched more than 150 fold in the particles as compared to its content in total cellular tRNA where it represents less than 0.1% (initiator tRNA(Met) and tRNA(Ser)AGA being 11 and 4 fold enriched respectively). This tRNA is the only species coded by the tDNA(Ser)GCT gene which is found in three copies per genome since no other corresponding expressed tRNA could be detected. This gene is thus very poorly expressed. The high concentration of tRNA(Ser)GCU in the particles compared to its very low cellular content led us to consider its possible implication in Ty specific processes.

Pleiotropic effect of a point mutation in the yeast SUP4-o tRNA gene: in vivo pre-tRNA processing in S. cerevisiae.

The expression of mutant tyrosine-inserting ochre suppressor SUP4-o tRNA genes in vivo in S. cerevisiae was examined as a basis for further studies of tRNA transcription and processing. In vivo yeast precursor tRNAs have been identified by filter hybridization and primer extension analysis. We have previously shown that a mutant SUP4-o tRNA gene with a C52----A52 transversion at positive 52 (C52----A52(+IVS) allele) was transcribed but that the primary transcript was not processed correctly. We show here that 5' and 3' end processing as well as splicing are defective for this mutant but that the 5' end processing is restored when the intron is removed from the gene by oligonucleotide directed mutagenesis (C52----A52(-IVS) allele). Our results imply that the C52----A52 transversion by itself cannot account for the lack of susceptibility to RNase P cleavage but that the overall tertiary structure of the mutant tRNA precursor is destabilized by the intron/anticodon stem. A second consequence of the C52----A52 transversion is to prevent complete maturation of the tRNA precursor at its 3' end since intermediates containing incompletely processed 3' trailers accumulate in the yeast cells transformed with the C52----A52(-IVS) allele. A correct structure of the T stem might therefore define a structural feature required for the recognition of the 3' processing activity.

Comparison of Two Restraint Systems for Pelvic Stabilization during Isometric Lumbar Extension Strength Testing.

This study was supported in part by a grant from MedX Inc., Ocala, FL. Among strength testing methods, varying degrees of stabilization are used. The purpose of this study was to compare isometric lumbar extension strength values obtained from two different restraint systems designed to isolate the lumbar extensors through pelvic stabilization. Both restraint systems stabilized the pelvis by preventing movement of the lower extremities during testing with the subject in a seated position. One restraint system (KNEE) applied pressure just below the knees while the lower leg was positioned at 120 degrees of knee flexion. The other (FOOT) applied pressure to the bottom of the feet while the lower leg was positioned at 60 degrees of knee flexion. Fifteen men (age = 37 +/- 10 yr; height = 177.7 +/- 5.3 cm; weight = 61.4 +/- 10.9 kg) and six women (age = 43 +/- 7 yr; height = 170.9 +/- 7.9 cm; weight = 61.4 +/- 10.9 kg) were tested at seven positions through 72 degrees range of motion with each restraint system. Analysis of variance for repeated measures indicated a significant difference (p 0.05) between restraints were noted at 24, 12, or 0 degrees flexion. Thus, the restraint system employed can influence lumbar extension strength values and affect the shape of the isometric lumbar extension strength curve. J Orthop Sports Phys Ther 1992;15(1):37-42.

Limited range-of-motion lumbar extension strength training.

The purpose of this study was to evaluate the effect of limited range-of-motion (ROM) resistance training on the development of lumbar extension strength through a 72 degrees ROM. Thirty-three men and 25 women (age = 30 +/- 11 yr) were randomly assigned to one of three training groups or a control group (C; n = 10) that did not train. Training was conducted once per week for 12 wk and consisted of one set of 8-12 repetitions of variable resistance lumbar extensions until volitional fatigue. Group A (n = 18) trained from 72 degrees to 36 degrees of lumbar flexion; group B (n = 14) from 36 degrees to 0 degree of lumbar flexion; and group AB (n = 16) from 72 degrees to 0 degree of lumbar flexion. Prior to and after training, isometric lumbar extension torque was assessed at 72 degrees, 60 degrees, 48 degrees, 36 degrees, 24 degrees, 12 degrees, and 0 degree of lumbar flexion. Analysis of covariance showed that groups A, B, and AB increased lumbar extension torque (P less than or equal to 0.05) at all angles measured when compared with C. The greatest gains in torque were noted for groups A and B in their respective ranges of training but A and B did not differ from AB (P greater than 0.05) at any angle. These data indicate that limited ROM lumbar extension training through a 36 degrees ROM is effective for developing strength through 72 degrees of lumbar extension.

Rheumatoid knee: role of gadopentetate-enhanced MR imaging.

Physical examination is often insufficient in distinguishing between joint effusion and inflamed synovium in the knee joints of patients with rheumatoid arthritis. The authors prospectively evaluated the role of intravenously administered gadopentetate dimeglumine in distinguishing between these two conditions. Fourteen patients with classic rheumatoid arthritis were examined first by a rheumatologist and then by means of magnetic resonance (MR) imaging with T1- and T2-weighted sequences. T1-weighted images were also obtained following the intravenous administration of gadopentetate dimeglumine. T1-weighted images obtained prior to contrast material administration demonstrated an identical low-intensity signal from both effusion and inflamed synovium, and T2-weighted images demonstrated increased signal intensity in both cases. Intravenous administration of gadopentetate dimeglumine allowed distinction between effusion and abnormal synovium, with the effusion remaining of low signal intensity and the synovium demonstrating enhancement and increased signal intensity. The authors conclude that the use of gadopentetate allows distinction between synovial thickening and joint effusion in the knee, which may affect treatment decisions.

Accumulation and specific cleavage of 5S RNA in the isthmus of laying hen oviduct. Evidence for three chicken 5S RNA.

RNA extracts from the isthmus of laying hen oviduct contain truncated 5S RNA molecules that were found to be shorter at their 5' terminus as compared to native 5S RNA I and II. Moreover one of the truncated species differs from 5S RNA I by the absence of the 3' end nucleotide. The truncated forms increase of about 70% the total 5S RNA (intact + truncated) in the isthmus, as compared to the other studied tissues. Furthermore 5S RNA I is heterogeneous: 25% have A instead of U at the 3' end, and some evidence was obtained for the existence of two 5S RNA I conformers.

Primary structure of three tRNAs from brewer's yeast: tRNAPro2, tRNAHis1 and tRNAHis2.

The primary structures of three brewer's yeast tRNAs: tRNAPro2 and tRNAHis1 and 2 have been determined (Formula:see text) The U* in the anticodon U*-G-G of tRNAPro2 is probably a derivative of U; tRNAPro2 has 80 per cent homology with mammalian tRNAsPro. tRNAHis1 and tRNAHis2 differ by only 5 nucleotides; they have identical anticodons and may therefore recognize both codons for histidine; they have an additional nucleotide at the 5' end. As in all other sequenced tRNAsHis this nucleotide is not paired with the fourth nucleotide from acceptor adenosine. All three sequenced tRNAs have a low degree of homology with their counterparts from yeast mitochondria.

Primary structure of bovine liver tRNATrp.

Purified tRNATrp from bovine liver, accepting 1700 pmol tryptophan per A260nm unit, was completely digested with pancreatic ribonuclease and T1 ribonuclease. The sequences of the resulting oligonucleotides were determined and the primary structure of the tRNA was deduced. These analyses showed numerous incomplete post-transcriptional modifications, and several positions heterogenously occupied by two different nucleotides, which lead us to think that in bovine liver there exist a mixture of several tRNATrp.