Increased acute and chronic mitotic activity in rat laryngeal muscles after botulinum toxin injection

OBJECTIVES: To characterize the acute and chronic cellular effects of botulinum toxin (BT) injection into rat laryngeal muscles. A complete characterization of these effects is important because patients with focal dystonias of the head and neck are commonly treated with BT injection. Further, potential muscular changes in the larynx must be carefully delineated owing to the critical phonatory and airway protective functions of these muscles. STUDY DESIGN: The acute and chronic cellular effects of BT injection were studied using 5'-bromo 2'-deoxyuridine (BrdU) following single and repeated BT injection into rat laryngeal muscles. BrdU is incorporated into mitotically active nuclei such that changes in cell proliferative behavior following BT injection can be monitored. RESULTS: Increased mitotic activity was detected in the tissue samples studied following BT injection. Differences in the times of the peak distribution of BrdU-labeled cells in each laryngeal muscle were observed. This may be related to the diffusion effects of BT. Prolonged muscle fiber changes, including splitting, were also observed as the result of repeated BT injection. CONCLUSIONS: The results of this study suggest that BT may induce a proliferative response in muscle tissue.     

Extraction of high-resolution frames from video sequences

The human visual system appears to be capable of temporally integrating information in a video sequence in such a way that the perceived spatial resolution of a sequence appears much higher than the spatial resolution of an individual frame. While the mechanisms in the human visual system that do this are unknown, the effect is not too surprising given that temporally adjacent frames in a video sequence contain slightly different, but unique, information. This paper addresses the use of both the spatial and temporal information present in a short image sequence to create a single high-resolution video frame. A novel observation model based on motion compensated subsampling is proposed for a video sequence. Since the reconstruction problem is ill-posed, Bayesian restoration with a discontinuity-preserving prior image model is used to extract a high-resolution video still given a short low-resolution sequence. Estimates computed from a low-resolution image sequence containing a subpixel camera pan show dramatic visual and quantitative improvements over bilinear, cubic B-spline, and Bayesian single frame interpolations. Visual and quantitative improvements are also shown for an image sequence containing objects moving with independent trajectories. Finally, the video frame extraction algorithm is used for the motion-compensated scan conversion of interlaced video data, with a visual comparison to the resolution enhancement obtained from progressively scanned frames.     

The gap between cryptography and information security

Few controls available to information security professionals today are more potentially powerful than is encryption. Among the many important benefits of encryption are data confidentiality, integrity of data and system files, protection against repudiation in business and other transactions, assurance of individuals’ identity, protection against cheating in voting and contract signing, and others. Security professionals are required to know at least the basics of cryptography to pass professional certification tests such as the CISSP exam; they must often know much more to be able to be proficient on the job. A number of vendors have produced impressive encryption products for desktop encryption, authentication methods, virtual private networks (VPNs), and digital signatures. Significant advances in cryptography and cryptanalysis research have also occurred over the years.     

Topoisomerase function during replication-independent chromatin assembly in yeast

DNA topoisomerases I and II are the two major nuclear enzymes capable of relieving torsional strain in DNA. Of these enzymes, topoisomerase I plays the dominant role in relieving torsional strain during chromatin assembly in cell extracts from oocytes, eggs, and early embryos. We tested if the topoisomerases are used differentially during chromatin assembly in Saccharomyces cerevisiae by a combined biochemical and pharmacological approach. As measured by plasmid supercoiling, nucleosome deposition is severely impaired in assembly extracts from a yeast mutant with no topoisomerase I and a temperature-sensitive form of topoisomerase II (strain top1-top2). Expression of wild-type topoisomerase II in strain top1-top2 fully restored assembly-driven supercoiling, and assembly was equally efficient in extracts from strains expressing either topoisomerase I or II alone. Supercoiling in top1-top2 extract was rescued by adding back either purified topoisomerase I or II. Using the topoisomerase II poison VP-16, we show that topoisomerase II activity during chromatin assembly is the same in the presence and absence of topoisomerase I. We conclude that both topoisomerases I and II can provide the DNA relaxation activity required for efficient chromatin assembly in mitotically cycling yeast cells.     

Fibre Surface Energy Characterization

A new technique has been developed to study the surface energy characteristics of small diameter fibres. This method is tensiometric and based on wetting properties in a two phase liquid system. Two types of carbon fibre have been investigated under both static and dynamic conditions in immersion and emersion.

The high strength fibre, which was found to have a polymeric coating, gave reproducible results consistent with typical values for a polymer. However, the high modulus fibre could not be characterized due to considerable scatter in the experimental results. It is suggested that the source of this phenomenon is the existence of surface energy gradients which leads to hysteresis effects.     

Effect of columnar defects on theJ c anisotropy of YBa2Cu3O7−δ thin films and YBa2Cu3O7−δ /PrBa2Cu3O7−δ multilayers

Epitaxial YBa₂Cu₃O_7?δ thin films (YBCO) and YBa₂Cu₃O_7?δ /PrBa₂Cu₃O_7?δ multilayers (Y/Pr) were irradiated with high-energy heavy ions (770 Mev²⁰⁸Pb) under various directionsφ relative to thec-axis. The irradiation resulted in columnar defects tilted byφ from thec-axis. The angular dependence of their pinning activity was studied by measuring the anisotropy of the critical current density. TheJ _c (B, T,?) behavior of the irradiated YBCO thin films showed an additional peak, which exceeds the intrinsic pinning peak, exactly at the irradiation direction. The Y/Pr multilayers, however, showed an isotropicT _c -enhancement by a factor of 5, without any additional structure in theJ _c(B, T,?) curve.     

Changes in ribosomal ribonucleic acid content within in vitro-produced bovine embryos

The abundance of 28S, 18S, and 5S rRNA was measured by Northern blot techniques applied to RNA samples extracted from bovine oocytes and preattachment embryos produced by in vitro procedures. Total RNA content was estimated by comparing the intensity of hybridization signals of 28S and 18S rRNA probes to embryo RNA samples and to standard curves generated from bovine ovary or bovine oviduct cell RNA. RNA content declined from the oocyte to the morula stage (2.4 +/- 0.3 ng/oocyte, 1.7 +/- 0.5 ng/1-cell embryo, 2.2 +/- 0.9 ng/2- to 4-cell embryo, 0.8 +/- 0.2 ng/6- to 8-cell embryo, and 0.7 +/- 0.2 ng/morula). A marked increase in RNA content, based on levels of hybridization to 28S and 18S rRNA, was observed in blastocysts, in which values averaged 5.3 +/- 0.6 ng/embryo. On a relative basis, 5S rRNA abundance followed a pattern similar to that of 28S and 18S rRNA across the early development period to the blastocyst stage.     

Tendons attached to prostheses by tendon-bone block fixation: an experimental study in dogs

To develop a method of tendon attachment to a metallic endoprosthesis, we evaluated fixation strength, clinical function of the tendon, and morphological changes in an experimental model. The canine supraspinatus tendon was removed from the greater tubercle of the humerus and attached to a titanium prosthesis. In 12 animals, the bone block underlying the tendon insertion was preserved and attached in one limb; the soft part of the tendon was attached directly to the prosthesis in the contralateral limb. Fixation strength was evaluated after 16 weeks of in vivo implantation (12 specimens) and compared with the in vitro fixation strength (12 specimens) and with intact normal controls (six specimens from cadavera). Function of the tendon in vivo was evaluated by force-plate analysis (at 3-week intervals). All specimens were evaluated histologically. Sixteen weeks after surgery, the tendon-bone block attachment was significantly stronger (mean, 16%) than the direct tendon attachment and not significantly different from the normal control, and the direct tendon attachment was significantly weaker (mean, 68%) than the normal control. There was significantly more weight-bearing on the limbs with a tendon-bone block attachment than on the limbs with a direct tendon attachment at both 3 and 6 weeks postoperatively. Both front legs showed increased weight-bearing with time, but the differences were not statistically significant. Anchorage by tissue ingrowth to the titanium prosthesis was found consistently--there was bone ingrowth in the tendon-bone block attachments and fibrous tissue ingrowth in the direct tendon attachments. When a bone block was preserved, the strength and stiffness were comparable with those of a normal tendon insertion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Positron emission yields for encapsulated Na sources

We have measured the total γ-activity and the emitted positron yields from two commercial ²²Na sources ( 5 mCi and 70 mCi). For the weaker source, we find good agreement between the number of positrons expected (based on γ-yield measurements) and those observed, after estimating the effect of positron absorption in the Ti window of the source capsule. The yield of positrons from the stronger source is a factor of two lower than expected. Reasons for the discrepancy are discussed.