Internal rectal intussusception seldom develops into total rectal prolapse

PURPOSE: This study was designed to analyze how often internal rectal intussusception develops into total rectal prolapse. METHODS: Repeated investigations with defecography were performed in 312 patients because of persisting symptoms. In 79 patients who had a rectal intussusception at the first defecography, results of the second defecography and the patients' records were studied. RESULTS: A total of 38 patients had not undergone any surgical treatment of rectal intussusception or rectal prolapse between the first and second defecographies. One of these patients had a rectal prolapse at the second defecography, and another developed a clinical prolapse after the second defecography. CONCLUSIONS: The present study demonstrates that the risk of developing a rectal prolapse in patients with rectal intussusception is small. This risk should, therefore, not be used as an indication for surgery.     

Comparison of the QSAR models for toxicity and biodegradability of anilines and phenols

Structure-activity models for toxicity and biodegradability of groups of m-anilines and p-phenols were developed and compared. Hydrophobicity was the most important property in determining toxicity. Whereas, electronic and steric properties were the more important in modeling biodegradation.     

When firewalls fail: Lessons learned from firewall testing

Firewall testing, if properly conducted, is advantageous in revealing specific ways that firewalls can be breached or bypassed. A previous issue of Network Security (March 1996) describes a systematic methodology for testing firewalls that SRI Consulting uses. SRI Consulting has conducted a sufficient number of tests to be able to generalize about how firewalls in real-life environments have succumbed to attacks based on this methodology. Unscreened services in hosts protected by the firewall have been the most frequently exploited exposure, followed by exploitation of services that run on the firewall itself, then by exploitation of a dangerous relationship between a firewall and an external router or host on the DMZ. Because testing results depend on the particular testing methodology used, these illustrate that negative entropy in firewalls does occur. This article also provides a list of action items for firewall and network administrators to ensure that firewall defences are adequate.     

Retrieving shape information from multiple images of a specularsurface

In many remote sensing and machine vision applications, the shape of a specular surface such as water, glass, or polished metal must be determined instantaneously and under natural lighting conditions. Most image analysis techniques, however, assume surface reflectance properties or lighting conditions that are incompatible with these situations. To retrieve the shape of smooth specular surfaces, a technique known as specular surface stereo was developed. The method analyzes multiple images of a surface and finds a surface shape that results in a set of synthetic images that match the observed ones. An image synthesis model is used to predict image irradiance values as a function of the shape and reflectance properties of the surface, camera geometry, and radiance distribution of the illumination. The specular surface stereo technique was tested by processing four numerical simulations-a water surface illuminated by a low- and high-contrast extended light source, and a mirrored surface illuminated by a low- and high-contrast extended light source. Under these controlled circumstances, the recovered surface shape showed good agreement with the known input     

Modulation of telomerase activity by telomere DNA-binding proteins in Oxytricha

Telomere proteins protect the chromosomal terminus from nucleolytic degradation and end-to-end fusion, and they may contribute to telomere length control and the regulation of telomerase. The current studies investigate the effect of Oxytricha single-stranded telomere DNA-binding protein subunits alpha and beta on telomerase elongation of telomeric DNA. A native agarose gel system was used to evaluate telomere DNA-binding protein complex composition, and the ability of telomerase to use these complexes as substrates was characterized. Efficient elongation occurred in the presence of the alpha subunit. Moreover, the alpha-DNA cross-linked complex was a substrate for telomerase. At higher alpha concentrations, two alpha subunits bound to the 16-nucleotide single-stranded DNA substrate and rendered it inaccessible to telomerase. The formation of this alpha . DNA . alpha complex may contribute to regulation of telomere length. The alpha . beta . DNA ternary complex was not a substrate for telomerase. Even when telomerase was prebound to telomeric DNA, the addition of alpha and beta inhibited elongation, suggesting that these telomere protein subunits have a greater affinity for the DNA and are able to displace telomerase. In addition, the ternary complex was not a substrate for terminal deoxynucleotidyltransferase. We conclude that the telomere protein inhibits telomerase by rendering the telomeric DNA inaccessible, thereby helping to maintain telomere length.     

In vitro culture retards spontaneous activation of cell cycle progression and cortical granule exocytosis that normally occur in in vivo unfertilized mouse eggs

A microchip method has been developed for massive and parallel thermodynamic analyses of DNA duplexes. Fluorescently labeled oligonucleotides were hybridized with oligonucleotides immobilized in the 100 x 100 x 20 mum gel pads of the microchips. The equilibrium melting curves for all microchip duplexes were measured in real time in parallel for all microchip duplexes. Thermodynamic data for perfect and mismatched duplexes that were obtained using the microchip method directly correlated with data obtained in solution. Fluorescent labels or longer linkers between the gel and the oligonucleotides appeared to have no significant effect on duplex stability. Extending the immobilized oligonucleotides with a four-base mixture from the 3'-end or one or two universal bases (5-nitroindole) from the 3'- and/or 5'-end increased the stabilities of their duplexes. These extensions were applied to increase the stabilities of the duplexes formed with short oligonucleotides in microchips, to significantly lessen the differences in melting curves of the AT- and GC-rich duplexes, and to improve discrimination of perfect duplexes from those containing poorly recognized terminal mismatches. This study explored a way to increase the efficiency of sequencing by hybridization on oligonucleotide microchips.     

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.