Library

Notes: Abstract: The diagnosis of occult breast epithelial proliferation by random fine needle aspiration biopsy (FNAB) of the breast remains controversial. However, the detection of proliferative change using FNAB would potentially improve assessment of breast cancer risk among women entering chemoprevention trials. To assess the validity of this procedure in risk stratification for breast cancer, we performed FNAB on 70 women while they were anesthetized for a variety of general surgical procedures. The contralateral breasts of 32 women with a history of breast cancer (cases) and both breasts of 38 women at standard risk for breast cancer (controls) were subjected to random FNAB. Cytospin preparations from four pooled FNAB passes from each breast were stained by the papanicolaou technique and interpreted according to previously published criteria. Inadequate aspirates comprised 40% (28/70) of the samples. In the remaining cases, there was a statistically significant difference between the frequency of proliferative changes and atypical hyperplasia in high-risk cases versus controls (Pearson χ2= 9.98, p = 0.019). The contralateral breasts of women with sporadic breast cancer demonstrated proliferative changes at higher rates than breasts of asymptomatic control women. Similarly, in a logistic regression model, the odds of a diagnosis of breast cancer increased with the presence of proliferative changes with or without atypia [odds ratio (OR) = 3.6, p 〈 0.02]. This study suggests that FNAB may have a role in the further stratification of high-risk women and provide a suitable sample for the monitoring of surrogate end point biomarkers in chemoprevention trials.

Notes: Equilibrium molecular dynamics simulations are used to obtain the pressure and configurational chain properties of near-perfect, off-lattice, trifunctional hard-chain networks of chain lengths 20, 35, 50, and 100, and of tetrafunctional hard-chain networks of chain lengths 20, 35, and 50 over a range of packing fractions. Our simulation results show that the variation of network pressure with density is similar to that of uncrosslinked chain systems of the same chain length, except at low densities where the network pressure shows a negative region, as first observed by Escobedo and de Pablo. We present a theoretical treatment leading to an analytical expression for the network pressure as the sum of liquid-like and elastic contributions. The liquid-like contribution is obtained by extending the generalized Flory-dimer theory to networks, and the elastic contribution is obtained by treating the network as a set of interpenetrated dendrimers and using an ideal chain-spring analogy to calculate the free energy. The theoretical predictions for network pressure are in good agreement with simulation data. © 1999 American Institute of Physics.

Notes: The nature and distribution of 14C atrazine (2- chloro- 4 -ethylamino- 6 -isopropylamino-s-tria- zine) residues in resistant and susceptible canola (Brassica napus L.) varieties were studied. Radiolabelled atrazine was applied to the plants just before the flowering stage and continued for 10 days. The plants were harvested 3, 10 and 25 days after the end of the treatment. The roots, shoots and pods of each plant were exhaustively extracted with methanol. The 14C distribution between the methanol extracts and the plant matrix fractions (bound residues) was similar for the two varieties. High-pressure liquid Chromatographie analysis of the methanol extracts showed that they contained two unknown metabolites (possibly conjugates) in addition to atrazine. The bound 14C residues were released by supercritical methanol extraction and analysed by thin-layer chromato- graphy, gas chromatography and high-pressure liquid chromatography. Several 14C components in the released material were detected. Bound atrazine and its two dealkylated metabolites represented only a very small portion (10–18%) of the total bound 14C residues in the plants. Résidus 14C extractibles et liés chez des plantes de canola (Brassica napus) traitées avec de l'atrazine radioactivement marquéeLa nature et la distribution de résidus d'atrazine 14C (2-chloro 4-ethylamino-6-isopropylamino-s-triazine) chez des variétés de canola résistantes et sensibles ont étéétudiés. De l'atrazine radiomarquée a été appliquée aux plantes juste avant la floraison et poursuivie pendant 10 jours. Les plantes ont été récoltées 3, 10 et 25 jours après la fin du traitement. Les racines, tiges et gousses de chaque plante ont été complètement extractées avec du methanol. La distribution du 14C entre les extraits méthanol et les fractions de plantes matricielles (liées) a été similaire pour les 2 variétés. Des analyses HPLC des extraits méthanol ont montré qu'ils contenaient deux metabolites inconnus (probablement combinés) en plus de l'atrazine. Les résidus 14C liés étaient libérés par une extraction au méthanol supercritique et analysé par Chromatographie en couche mince, Chromatographie gazeuze et HPLC. Plusieurs composés dans le matériel libéré ont été détectés. L'atrazine liée et ses deux metabolites dealklyés représentaient seulement une très petite part (10–18%) de la totalité des résidus 14C liés dans les plantes. Gebundene und extrahierbare 14C-Rückstände in mit radioaktiv markiertem Atrazin behandeltem Raps (Brassica napus)Die Art und die Verteilung von Rückständen von 14C-Atrazin (2-Chlor-4-ethylamin-6-iso- propylamin-s-triazin) wurden in resistenten und empfindlichen Varietäten von Raps (Brassica napus) untersucht. Das radioaktiv markierte Herbizid wurde kurz vor der Blüte und 10 Tage weiter auf die Pflanzen ausgebracht. Die Pflanzenproben wurden 3, 10 und 25 Tage nach dem Ende der Behandlung gezogen. Wurzeln, Sprosse und Schoten wurden erschöpfend mit Methanol extrahiert. Die 14C-Verteilung in den Methanolextrakten und im Pflanzenmaterial (gebundene Rückstände) war bei beiden Sorten ähnlich. Bei der HPLC-Analyse wurden in den Methanolextrakten neben Atrazin 2 unbekannte Metaboliten (vermutlich Konjugate) gefunden. Die gebundenen 14C-Rückstände wurden im Überkritischen Verfahren mit Methanol extrahiert und dünnschicht-, gas-und HPL-chromatographisch analysiert. Verschiedene 14C-Verbindungen wurden gefunden. Gebundenes Atrazin und seine beiden de-alkylierten Metaboliten machten nur eine kleinen Anteil (10 bis 18%) der gesamten gebundenen 14C-Rückstände aus.

Notes: Terbacil (5-chloro-6-methyl-3-butyluracil) residues did not accumulate in peach orchard soil after seven consecutive annual spring applications of the herbicide at the rate of 4.5 kg/ha although carry-over of terbacil from year to year occurred. Terbacil was lost by degradation and leaching and the time required for a 50% decrease in surface soil concentration was 5–7 months in the sandy loam soil. The major part of the residues was found in the upper 15 cm of the soil profile and smaller amounts were detected to a depth of 60 cm. Terbacil leached readily in prepared columns of sandy loam soil in proportion to the amount of water added. The residual levels of terbacil in the orchard were phytotoxic to oats planted 3 years after the last application.