Early toxicity from preoperative radiotherapy with continuous infusion 5-fluorouracil for resectable adenocarcinoma of the rectum: A phase II trial for the Trans-Tasman Radiation Oncology Group

Purpose: To assess the toxicity and the efficacy of preoperative radiotherapy with continuous infusion 5-fluorouracil (5-FU) for locally advanced adenocarcinoma of the rectum. Methods and Materials: Eligible patients had newly diagnosed localized adenocarcinoma of the rectum within 12 cm of the anal verge, Stage T3-4, and were suitable for curative resection. Eighty-two patients were treated with radiotherapy-50.4 Gy in 28 fractions in 5.6 weeks, given concurrently with continuous infusion 5-FU, using either 96-h/week infusion at 300 mg/m(2)/day or 7-days/week infusion at 225 mg/m(2)/day. Results: The median age was 59 years (range, 27-87), and 67% of patients were male. Pretreatment stages of the rectal cancer were T3, 89% and resectable T4, 11%, with endorectal ultrasound confirmation in 67% of patients. Grade 3 acute toxicity occurred in 5 of 82 patients (6%; 95% confidence interval [CI], 2-14%). Types of surgical resection were anterior resection, 61%; abdominoperineal resection, 35%; and other procedures, 4%. There was no operative mortality. Anastomotic leakage after low anterior resection occurred in 3 of 50 patients (6%; 95% CI, 1-17%). The pathologic complete response rate was 16% (95% CI, 9-26%). Pathologic Stages T2 or less occurred in 51%. Conclusion: Preoperative radiotherapy with continuous infusion 5-FU for locally advanced rectal cancer is a safe regimen, with a significant downstaging effect. It does not seem to lead to a significant increase in serious surgical complications. (C) 2001 Elsevier Science Inc.

Reversible luminescence thermochromism in dipotassiumsodium tris[dicyanoargentate(I)] and the role of structural phase transitions

As a function of temperature, the layered compound K2Na[Ag(CN)213 displays dramatic variations in luminescence thermochromism with major trend changes occurring around 80 K. In order to understand these interesting optical properties, high-resolution neutron diffraction investigations were performed on a polycrystalline sample of this material in the temperature range from 1.5 to 300 K, and previous synchrotron X-ray data of Larochelle et al. (Solid State Commun. 114, 155 (2000)) were reinterpreted. The corresponding significant structural changes were found to be continuous with an anomalous increase of the monoclinic c-lattice parameter with decreasing temperature, associated with slight reorientations of two inequivalent, approximately linear N-C-Ag-C-N units. In the whole temperature range, the crystal structure is monoclinic with the space group C2/m. Based on the structural results, the major luminescence thermochromism changes around 80 K are attributed to the dominance of a back energy transfer process from low- to high-energy excitons at high temperatures. (E) 2002 Elsevier Science (USA).

Acute symptoms, not rectally administered sucralfate, predict for late radiation proctitis: Longer term follow-up of a phase III trial - trans-Tasman radiation oncology group

Image : To assess the potential for sucralfate administered rectally to reduce the risk of late rectal morbidity in patients undergoing nonconformal radiotherapy (RT) for carcinoma of the prostate and to study the variables potentially contributing to late rectal morbidity and particularly to explore the relationship between acute and late toxicity. Image : Eighty-six patients with localized prostate carcinoma were randomized in a double-blind, placebo-controlled study to a daily enema of 3 g of sucralfate in a 15-mL suspension or the same suspension without sucralfate. The enema began the first day of RT and was continued for 2 weeks after treatment completion. The primary end point of the study was acute Radiation Therapy Oncology Group (RTOG)/European Organization for Research and Treatment of Cancer (EORTC) toxicity; however, the patients were followed for an additional 5 years on a 6-month basis. The evaluation included late RTOG/EORTC toxicity and a patient self-assessment questionnaire. Image : With a median follow-up of 5 years, the Kaplan-Meier probability of late Grade 2 RTOG/EORTC toxicity was 12% (95% confidence interval [CI] 2–22%) for placebo and 5% (95% CI 0–12%) for sucralfate (p = 0.26). The probability of late rectal bleeding was 59% (95% CI 45–73%) for placebo and 54% (95% CI 40–68%) for sucralfate. No statistically significant difference was found between the treatment arms for the peak incidence of any of the other patient self-assessment variables. Cox proportional hazards modeling indicated acute RTOG/EORTC toxicity of Grade 2 or greater was associated with a hazard ratio of 2.74 (95% CI 1.31–5.73) for the development of late toxicity of Grade 1 or greater. Substituting the patient self-assessment variables for acute RTOG/EORTC toxicity revealed that rectal pain of a moderate or severe grade during RT was the best predictor of the subsequent development of late toxicity, with a hazard ratio of 3.44 (95% CI 1.68–7). Image : The results of this study do not support the use of sucralfate administered rectally as a method for reducing the late toxicity of nonconformal RT for prostate cancer. There appears to be an association between the development of acute and subsequent late toxicity, although the nature of this association remains to be determined

Precursor scavenging of resistive grain-boundary phase in 8 mol % ytterbia-stabilized zirconia

The grain-boundary conduction of 8 mol % ytterbia-stabilized zirconia (8YbSZ) was improved markedly by precursor scavenging via the two-stage sintering process. The most significant increase in the grain-boundary conductivity was found when the sample, whose conductivity was higher than that via Al2O3-derived scavenging, was heat-treated at 1250degreesC for greater than or equal to 20 h. The formation of a stable Si-containing phase such as ZrSiO4 during the first-stage heat-treatment was suggested as one probable scavenging route from the optimal heat-treatment temperature (HTT), long duration time (>20 h) at HTT, and the stability of the formed phase up to sintering temperatures (1500degrees C). (C) 2002 The Electrochemical Society.

Grafted fluoropolymers as supports for solid-phase organic chemistry: Preparation and characterization

Solid-phase organic chemistry has rapidly expanded in the last decade, and, as a consequence, so has the need for the development of supports that can withstand the extreme conditions required to facilitate some reactions. The authors here prepare a thermally stable, grafted fluoropolymer support (see Figure for an example) in three solvents, and found that the penetration of the graft was greatest in dichloromethane.

Empirical evidence for ultrametric structure in multi-layer perceptron error surfaces

Combinatorial optimization problems share an interesting property with spin glass systems in that their state spaces can exhibit ultrametric structure. We use sampling methods to analyse the error surfaces of feedforward multi-layer perceptron neural networks learning encoder problems. The third order statistics of these points of attraction are examined and found to be arranged in a highly ultrametric way. This is a unique result for a finite, continuous parameter space. The implications of this result are discussed.

Phase variation in meningococcal lipooligosaccharide biosynthesis genes

Neisseria meningitidis expresses a range of lipooligosaccharide (LOS) structures, comprising of at least 13 immunotypes (ITs). Meningococcal LOS is subject to phase variation of its terminal structures allowing switching between ITs, which is proposed to have functional significance in disease. The objectives of this study were to investigate the repertoire of structures that can be expressed in clinical isolates, and to examine the role of phase-variable expression of LOS genes during invasive disease. Southern blotting was used to detect the presence of LOS biosynthetic genes in two collections of meningococci, a global set of strains previously assigned to lineages of greater or lesser virulence, and a collection of local clinical isolates which included paired throat and blood isolates from individual patients. Where the phase-variable genes lgtA, lgtC or IgtG were identified, they were amplified by PCR and the homopolymeric tracts, responsible for their phase-variable expression, were sequenced. The results revealed great potential for variation between alternate LOS structures in the isolates studied, with most strains capable of expressing several alternative terminal structures. The structures predicted to be currently expressed by the genotype of the strains agreed well with conventional immunotyping. No correlation was observed between the structural repertoire and virulence of the isolate. Based on the potential for LOS phase variation in the clinical collection and observations with the paired patient isolates, our data suggest that phase variation of LOS structures is not required for translocation between distinct compartments in the host. (C) 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Microbiological Societies.

The impact of genotyping error on haplotype reconstruction and frequency estimation

The choice of genotyping families vs unrelated individuals is a critical factor in any large-scale linkage disequilibrium (LD) study. The use of unrelated individuals for such studies is promising, but in contrast to family designs, unrelated samples do not facilitate detection of genotyping errors, which have been shown to be of great importance for LD and linkage studies and may be even more important in genotyping collaborations across laboratories. Here we employ some of the most commonly-used analysis methods to examine the relative accuracy of haplotype estimation using families vs unrelateds in the presence of genotyping error. The results suggest that even slight amounts of genotyping error can significantly decrease haplotype frequency and reconstruction accuracy, that the ability to detect such errors in large families is essential when the number/complexity of haplotypes is high (low LD/common alleles). In contrast, in situations of low haplotype complexity (high LD and/or many rare alleles) unrelated individuals offer such a high degree of accuracy that there is little reason for less efficient family designs. Moreover, parent-child trios, which comprise the most popular family design and the most efficient in terms of the number of founder chromosomes per genotype but which contain little information for error detection, offer little or no gain over unrelated samples in nearly all cases, and thus do not seem a useful sampling compromise between unrelated individuals and large families. The implications of these results are discussed in the context of large-scale LD mapping projects such as the proposed genome-wide haplotype map.

Phase variable restriction-modification systems in Moraxella catarrhalis

A repetitive DNA motif was used as a marker to identify novel genes in the mucosal pathogen Moraxella catarrhalis. There is a high prevalence of such repetitive motifs in virulence genes that display phase variable expression. Two repeat containing loci were identified using a digoxigenin-labelled 5'-(CAAC)(6)-3' oligonucleotide probe. The repeats are located in the methylase components of two distinct type III restriction-modification (R-M) systems. We suggest that the phase variable nature of these R-M systems indicates that they have an important role in the biology of M. catarrhalis. (C) 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Microbiological Societies.

Phase equilibria and thermodynamics of zinc fuming slags

A range of materials is treated in zinc fuming processes to recover metal values and produce benign slag waste products. The selection of the optimum process conditions in these various technologies can be greatly assisted by the use of a chemical thermodynamic model of the system. In this paper the effects of slag chemistry on the liquidus temperatures, subliquidus phase equilibria and thermodynamic properties are described by the F*A*C*T computer package with the new thermodynamic database of the ZnO-PbO-FeO-Fe2O3-CaO-SiO2 system. The implications of these findings for plant practice are discussed.

Experimental study of phase equilibria in the "FeO"-ZNO-(CaO+SiO2) system with the CaO/SiO2 weight ratio of 0.71 at metallic iron saturation

The pseudoternary section FeO-ZnO-(CaO + SiO2) with a CaO/SiO2 weight ratio of 0.71 in equilibrium with metallic iron has been experimentally investigated in the temperature range from 1000 degreesC to 1300 degreesC (1273 to 1573 K). The liquidus surface in this pseudoternary. section has been determined in the composition range of 0 to 33 wt pct ZnO and 30 to 70 wt pct (CaO + SiO2)The system contains primary-phase fields of wustite (FexZn1-xO1+y), zincite (ZnzFe1-zO), fayalite (FewZn2-wSiO4), melilite (Ca2ZnuFe1-uSi2O7), and pseudowollastonite (CaSiO3). The phase equilibria involving the liquid phase and the solid solutions have also been measured.

Phase equilibrium studies in the "MnO"-Al2O3-SiO2 system

Phase relations and the liquidus surface in the system "MnO"-Al2O3-SiO2 at manganese-rich alloy saturation have been investigated in the temperature range from 1373 to 1773 K. This system contains the primary-phase fields of tridymite and cristobalite (SiO2); mullite (3Al(2)O(3).2SiO(2)); corundum (Al2O3); galaxite (MnO.Al2O3); manganosite (MnO); tephroite (2MnO.SiO2); rhodonite (MnO.SiO2); spessartine (3MnO.Al2O3.SiO2); and the compound MnO.Al2O3.2SiO(2).

Phase equilibrium data and liquidus for the system "MnO"-CaO-(Al2O3+SiO2) at Al2O3/SiO2 of 0.41

Phase-equilibrium data and the liquidus for the system. "MnO"-CaO-(Al2O3-SiO2) at a manganese-rich alloy saturation have been determined in the temperature range from 1423 to 1723 K. The results are presented in the form of a pseudoternary section "MnO"-CaO-(Al2O3 + SiO2) with an Al2O3/SiO2 weight ratio of 0.41. The following primary phases are present in the range of conditions investigated:, 3Al(2)O(3).2SiO(2); SiO2; MnO.Al2O3-2SiO(2); (Mn,Ca)O.SiO2; 2(Mn,Ca)O.SiO2; MnO.Al2O3; (Mn,Ca)O; alpha-2CaO.SiO2; alpha'-2CaO.SiO2; 2CaO.Al2O3.SiO2; CaO.SiO2, and CaO.Al2O3.2SiO(2). The presence of alumina in this system is shown to have a significant effect on the liquidus compared to the system "MnO"-CaO-SiO2, leading to, the stabilization of the anorthite and gehlenite phases.