Aneurysms of splanchnic arteries

Aneurysms of splanchnic arteries represent an uncommon but important vascular disease, which many times presents itself as clinical emergency and often results in death. 11 patients with splanchnic aneurysms were treated in our Department during the last 15 years. These aneurysms were located in 5 cases in splenic artery, 4 cases in hepatic artery, 1 case in celiac axis and 1 case in right gastroepiploic artery. Surgical treatment of these aneurysms was successful in all but one patient (he died from rupture of a hepatic artery aneurysm). Giving an overall mortality similar to that reported in the literature. The treatment of these aneurysms is discussed, while literature about this uncommon disease is reviewed.     

Characterization of a baculovirus-encoded ATP-dependent DNA ligase

Sequence analysis of the Lymantria dispar multicapsid nucleopolyhedrovirus (LdMNPV) genome identified an open reading frame (ORF) encoding a 548-amino-acid (62-kDa) protein that showed 35% amino acid sequence identity with vaccinia virus ATP-dependent DNA ligase. Ligase homologs have not been reported from other baculoviruses. The ligase ORF was cloned and expressed as an N-terminal histidine-tagged fusion protein. Incubation of the purified protein with [alpha-32P]ATP resulted in formation of a covalent enzyme-adenylate intermediate which ran as a 62-kDa labeled band on a sodium dodecyl sulfate-polyacrylamide gel. Loss of the radiolabeled band occurred upon incubation of the intermediate with pyrophosphate, poly(dA) . poly(dT)12-18, or poly(rA) . poly(dT)12-18, characteristics of a DNA ligase II or III. The protein was able to ligate a double-stranded synthetic DNA substrate containing a single nick and inefficiently ligated a 1-nucleotide (nt) gap but did not ligate a 2-nt gap. It was able to ligate short, complementary overhangs but not blunt-ended double-stranded DNA. In a transient DNA replication assay employing six plasmids containing the LdMNPV homologs of the essential baculovirus replication genes, a plasmid containing the DNA ligase gene was neither essential nor stimulatory. All of these results are consistent with the activity of type III DNA ligases, which have been implicated in DNA repair and recombination.     

The key informant technique

The clinical outcome of 152 patients aged 65 years or over who were referred to the author's institute between August 1990 and August 1991 with certain specified gastrointestinal malignancies and acute, life-threatening abdominal conditions, were audited concurrently. Two groups were considered: patients aged 65-79 years and those over 80 years. The mortality rate within 30 days of surgery was 14 per cent in both age groups, although significantly fewer patients aged over 80 years (35 of 54) were considered suitable for surgery than in the 65-79 years age group (84 of 98) (0.01 > P > 0.001). Morbidity after operation and cost of treatment were not significantly different between the two groups. Two years after surgery 40 per cent of the patients aged over 80 years and 58 per cent of those aged 65-79 years were alive. Quality of life in these survivors was good with 85 per cent of those aged over 80 years living at home and 72 per cent fit enough to undertake light work.     

Degradation of retinyl acetate in simple solvent systems

The degradation of vitamin A acetate was studied by u.v. spectrophotometry in three solvent systems: absolute ethanol, ethanol: water (95:5) and hexanes. Three potential degradative factors were investigated: exposure to light, presence of air and temperature. In all systems studied, exposure to light was the major factor. In the ethanol systems, the rate constants calculated for the degradation in the presence or in the absence of oxygen are not significantly different. Analysis of the data by first order kinetic models yielded the best fit in all cases. The activation energy for the degradation reaction in absolute ethanol was found to be 56 ± 8 kJ/mol. The presence of water in ethanol did accelerate the reaction, but the dependence of the rate on the water content is not a simple one.     

A region within murine chromosome 7F4, syntenic to the human 11q13 amplicon, is frequently amplified in 4NQO-induced oral cavity tumors

Our previous reports have shown that two thirds of 4-nitroquinoline-1-oxide (4NQO)-induced murine oral squamous cell carcinomas (SCC) have Hras1 mutations. Loss of heterozygosity (LOH) involving the distal portion of chromosome (Chr) 7 occurred in half of the tumors with Hras1 mutations. Here, we demonstrate that five of six tumors with LOH have 4-8-fold amplification involving the distal portion of Chr 7 (7F4). Ccnd1. Fgf4 and Fgf3, within the most telomeric region of Chr 7 (70.5 cM), are co-amplified. The region is syntenic to a previously identified human amplicon at 11q13. Only one out of eight tumors without LOH at Chr 7 had twofold amplification; the other seven had no detectable amplification. Significant amplification is restricted to the chromosome with the Hras1 mutation. Gene amplification occurred without overexpression since only one of five tumors with amplification and one of six tumors without Ccnd1 amplification expressed increased protein. Although amplification of 11q13 occurs rather frequently in human tumors, 4NQO-induced oral cavity tumors in inbred mice are the first example of a murine tumor with consistent amplification. Our observations are strikingly similar to human head and neck SCC where overexpression of genes within the 11q13 amplicon is inconsistently detected. The amplification of genes localized to human 11q13 and the syntenic region on murine Chr 7 during tumorigenesis suggests that similar structural elements are present which predispose these regions to amplification during malignant transformation.     

Thin‐film encapsulated white organic light top‐emitting diodes using a WO3/Ag/WO3 cathode to enhance light out‐coupling

An alternative design of a semitransparent cathode for top‐emission white‐fluorescent organic light‐emitting diodes (OLEDs) has been investigated. The scope of this study was to improve the luminance of OLEDs used for displays while keeping the current density versus voltage characteristic unchanged for addressing purposes. The use of an optical simulation tool allowed the optimization of the tri‐layer cathode WO₃/Ag/WO₃ to increase the light out‐coupling coefficient of the device leading to an increased white emission compared with a reference device with a Ca/Ag cathode. An increase of ~40% in luminance has been calculated by simulation and experimentally confirmed. The p‐i‐n OLED structure underneath the tri‐layer cathode allowed an efficient injection of electrons independently from the work function of WO₃. The WO₃/Ag/WO₃ cathode has been also confirmed to be compatible with the atomic layer deposition technique for thin film encapsulation. Finally, lifetime measurements up to 600 h have been carried out to quantify the enhancements induced by the new cathode compared with the control device. It has been found that lifetimes of both cathode architectures are similar on this time scale, while the WO₃/Ag/WO₃ cathode shows a lower voltage drift versus aging.