Противоопухолевая эффективность контактной лучевой терапии в комбинации с фотосенсибилизатором хлоринового ряда в эксперименте

Authors have studied the antitumor efficacy of contact radiation therapy (CRT) in combination with a chlorin-based photosensitizer (PS) in an experiment on laboratory animals with transplanted tumors. The experimental study was performed in 50 white outbred rats weighing 250±50 g. Subcutaneously transplanted Pliss lymphosarcoma (PLS) and alveolar liver cancer RS1 (RS1) were used as tumor models. Chlorinbased PS photolon (RUE «Belmedpreparaty», Republic Belarus) was injected intravenously at a dose of 2.5 mg/kg. The radiation sessions were carried out 2.5–4 hours (depending on the tumor model) after the administration of the PS using the device «microSelectron HDR V3 Digital» («Nucletron», Netherlands) with a 192-Ir radiation source in single focal doses 5 and 10 Gy. All laboratory animals (for PLS and RS1) were subdivided into 5 groups of 5 animals each: intact control, CRT 5 Gy, CRT 10 Gy, PS + CRT 5 Gy, PS + CRT 10 Gy. For the PLS tumor model – on the 14th day from the beginning of the experiment Vav. in groups were 26.31±5.81; 22.45±6.97; 18.99±4.86; 10.75±5.18 and 28.06±2.85 cm3, respectively (p˂0.05). The coefficients of tumor growth inhibition in the experimental groups were 14.67%, 27.82%, 59.14% and 6.65%, respectively. The frequency of complete tumor regressions 60 days after the start of the experiment was 0%, 20%, 20%, 60%, and 20%, respectively. On RS1 tumor model – on the 14th day from the beginning of the experiment Vav. in groups were 4.48±1.03; 0.80±0.21; 0.29±0.09; 0.19±0.07 and 0.32±0.08 cm3, respectively (p=0.009). The coefficients of tumor growth inhibition in the experimental groups were 82.14%, 93.53%, 95.76% and 92.86%, respectively. The frequency of complete tumor regressions 60 days after the start of the experiment was 0%, 0%, 20%, 0%, and 0%, respectively. Systemic administration of chlorin-based PS before the CRT session increases the antitumor efficacy of radiation therapy in animals with transplantable tumors of different histological structure and growth patterns. The data obtained indicate that further studies of the radiosensitizing properties of PS are promising.Авторами изучена противоопухолевая эффективность контактной лучевой терапии (КЛТ) в комбинации с фотосенсибилизатором (ФС) хлоринового ряда в эксперименте на лабораторных животных с перевивными опухолями. Работа выполнена на 50 лабораторных животных (белые беспородные крысы) с массой тела 250±50 г. В качестве опухолевых моделей использовали лимфосаркому Плисса (ЛСП) и альвеолярный рак печени РС (РС1), перевитые подкожно. ФС хлоринового ряда фотолон (РУП «Белмедпрепараты», Беларусь) вводился внутривенно капельно в дозе 2,5 мг/кг массы тела. Сеанс КЛТ проводили через 2,5 – 4 ч (в зависимости от опухолевой модели) после введения ФС с использованием аппарата «microSelectron HDR V3 Digital» («Nucletron», Нидерланды) с источником излучения 192–Ir в разовых очаговых дозах (РОД) 5 и 10 Гр. Все лабораторные животные, как в подгруппе с ЛСП, так и в подгруппе с РС1, были разделены на 5 групп по 5 особей в каждой: интактный контроль, КЛТ РОД 5 Гр, КЛТ РОД 10 Гр, ФС + КЛТ РОД 5Гр, ФС + КЛТ РОД 10 Гр. На модели ЛСП на 14–е сутки от начала воздействий средний объем опухоли (Vср ) в группах составил 26,31±5,81; 22,45±6,97; 18,99±4,86; 10,75±5,18 и 28,06±2,85 см3, соответственно (р˂0,05). Коэффициент торможения роста опухоли (ТРО) в опытных группах составил 14,67%; 27,82%; 59,14% и - 6,65%, соответственно. Частота полных регрессий опухолей через 60 суток после начала эксперимента составила 0%, 20%, 20%, 60% и 20%, соответственно. На модели РС1 на 14–е сутки от начала воздействий Vср . в группах составил 4,48±1,03; 0,80±0,21; 0,29±0,09; 0,19±0,07 и 0,32±0,08 см3, соответственно (р=0,009). Коэффициент ТРО в опытных группах составил 82,14%; 93,53%; 95,76% и 92,86%, соответственно. Частота полных регрессий опухолей через 60 суток после начала эксперимента составила 0%, 0%, 20%, 0% и 0%, соответственно. Результаты исследования показали, что введение ФС хлоринового ряда перед сеансом КЛТ увеличивает противоопухолевую эффективность лучевой терапии у животных с различными по гистологической структуре и характеру роста перевивными опухолями. Полученные данные свидетельствуют о перспективности дальнейших исследований радиосенсибилизирующих свойств ФС

Ratio of the Isolated Photon Cross Sections at \sqrt{s} = 630 and 1800 GeV

The inclusive cross section for production of isolated photons has been measured in \pbarp collisions at $\sqrt{s} = 630$ GeV with the \D0 detector at the Fermilab Tevatron Collider. The photons span a transverse energy ($E_T$) range from 7-49 GeV and have pseudorapidity $|\eta| < 2.5$. This measurement is combined with to previous \D0 result at $\sqrt{s} = 1800$ GeV to form a ratio of the cross sections. Comparison of next-to-leading order QCD with the measured cross section at 630 GeV and ratio of cross sections show satisfactory agreement in most of the $E_T$ range.Comment: 7 pages. Published in Phys. Rev. Lett. 87, 251805, (2001

Search for Kaluza-Klein Graviton Emission in ppˉp\bar{p} Collisions at s=1.8\sqrt{s}=1.8 TeV using the Missing Energy Signature

We report on a search for direct Kaluza-Klein graviton production in a data sample of 84 ${pb}^{-1}$ of \ppb collisions at $\sqrt{s}$ = 1.8 TeV, recorded by the Collider Detector at Fermilab. We investigate the final state of large missing transverse energy and one or two high energy jets. We compare the data with the predictions from a $3+1+n$-dimensional Kaluza-Klein scenario in which gravity becomes strong at the TeV scale. At 95% confidence level (C.L.) for $n$=2, 4, and 6 we exclude an effective Planck scale below 1.0, 0.77, and 0.71 TeV, respectively.Comment: Submitted to PRL, 7 pages 4 figures/Revision includes 5 figure

Model of SNARE-Mediated Membrane Adhesion Kinetics

SNARE proteins are conserved components of the core fusion machinery driving diverse membrane adhesion and fusion processes in the cell. In many cases micron-sized membranes adhere over large areas before fusion. Reconstituted in vitro assays have helped isolate SNARE mechanisms in small membrane adhesion-fusion and are emerging as powerful tools to study large membrane systems by use of giant unilamellar vesicles (GUVs). Here we model SNARE-mediated adhesion kinetics in SNARE-reconstituted GUV-GUV or GUV-supported bilayer experiments. Adhesion involves many SNAREs whose complexation pulls apposing membranes into contact. The contact region is a tightly bound rapidly expanding patch whose growth velocity increases with SNARE density . We find three patch expansion regimes: slow, intermediate, fast. Typical experiments belong to the fast regime where depends on SNARE diffusivities and complexation binding constant. The model predicts growth velocities s. The patch may provide a close contact region where SNAREs can trigger fusion. Extending the model to a simple description of fusion, a broad distribution of fusion times is predicted. Increasing SNARE density accelerates fusion by boosting the patch growth velocity, thereby providing more complexes to participate in fusion. This quantifies the notion of SNAREs as dual adhesion-fusion agents

Search for single top quark production at D0 using neural networks

We present a search for electroweak production of single top quarks in ~90 pb^-1 of data collected with the DZero detector at the Fermilab Tevatron collider. Using arrays of neural networks to separate signals from backgrounds, we set upper limits on the cross sections of 17 pb for the s-channel process ppbar->tb+X, and 22 pb for the t-channel process ppbar->tqb+X, both at the 95% confidence level

Differential cross section for W boson production as a function of transverse momentum in proton-antiproton collisions at 1.8 TeV

We report a measurement of the differential cross section for W boson production as a function of its transverse momentum in proton-antiproton collisions at sqrt{s} = 1.8 TeV. The data were collected by the D0 experiment at the Fermilab Tevatron Collider during 1994-1995 and correspond to an integrated luminosity of 85 pb^{-1}. The results are in good agreement with quantum chromodynamics over the entire range of transverse momentum.Comment: Accepted by Physics Letters

Measurement of the ratio of differential cross sections for W and Z boson production as a function of transverse momentum in pbar p collisions at sqrt(s)=1.8 TeV

We report on a measurement of the ratio of the differential cross sections for W and Z boson production as a function of transverse momentum in proton-antiproton collisions at sqrt(s) = 1.8 TeV. This measurement uses data recorded by the D0 detector at the Fermilab Tevatron in 1994-1995. It represents the first investigation of a proposal that ratios between W and Z observables can be calculated reliably using perturbative QCD, even when the individual observables are not. Using the ratio of differential cross sections reduces both experimental and theoretical uncertainties, and can therefore provide smaller overall uncertainties in the measured mass and width of the W boson than current methods used at hadron colliders.Comment: 10 pages, 2 figures, to be published in Physics Letters

Search for narrow t(t)over-bar resonances in p(p)over-bar collisions at root s=1.8 TeV

A search for narrow resonances that decay into t (t) over bar pairs has been performed using 130 pb(-1) of data in the lepton + jets channel collected by the DO detector in p (p) over bar collisions at roots=1.8 TeV. There is no significant deviation observed from the standard-model predictions at a top-quark mass of 175 GeV/c(2). We therefore present upper limits at the 95% confidence level on the product of the production cross section and branching fraction to t (t) over bar for narrow resonances as a function of the resonance mass M-X. These limits are used to exclude the existence of a leptophobic top-color particle with mass M-X<560 GeV/c(2), using a theoretical cross section for a width Gamma(X)=0.012M(X)