Initial Experience with the Commercial Electron FLASH Research Extension

PURPOSE/OBJECTIVE(S)

The purpose of this study was to introduce a new commercial electron FLASH system that has the potential to become widely available for FLASH researchers globally. In this study, we first present the initial acceptance and commissioning tests for the FLASH system, and second, we highlight preliminary FLASH effect results from our cell studies.

MATERIALS/METHODS

A linear accelerator was converted into a commercial research platform with the FLASH Research Extension, enabling the generation of a powerful 16 MeV electron FLASH beam. The dosimetric and stability tests were conducted using various dosimeters (i.e., radiochromic film, optically stimulated luminescent dosimeters (OSLDs), and a plane-parallel ionization chamber). To evaluate the FLASH effect, normal and cancer cell lines were FLASH irradiated using different pulse repetition frequencies (PRF) of 18 pulses/s and 180 pulses/s.

RESULTS

The electron FLASH mode was able to generate over 1 Gy per pulse at the isocenter and a dose rate of up to 690 Gy/s near the accessory mount of the Linac gantry head. The charge collected by the plane-parallel ionization chamber at the highest PRF (i.e., 180 pulses/s) showed a linear relationship with the delivered number of pulses (i.e., 1 to 99 pulses) with a coefficient of determination (R2) of 0.9996. The absorbed dose measured using radiochromic film and OSLDs agreed within 3%, on average, and followed an inverse square law as the source-to-axis distance (SAD) varied for which the R2 values were 0.9972 and 0.9955 for radiochromic film and OSLDs, respectively. The profile of the FLASH beam was symmetrical but was not as flat as the conventional 16 MeV electron beam due to the use of a thinner custom scattering foil to reduce the degradation of the ultra-high dose rate. The depth-dose curve beyond the build-up region for the FLASH beam was similar to the conventional 16 MeV electron beam for which the range at 50% the maximum dose (R50) agreed within 0.5 mm. The FLASH beam output remained consistent over a 4-month period with a variation of 2.5%, on average. The FLASH sparing effect was observed in vitro for healthy human pancreatic cells. Furthermore, we observed that the highest PRF beam (180 pulses/s) was more effective at destroying pancreatic cancerous cells while minimizing damage to healthy cells compared to the lowest PRF beam (18 pulses/s).

CONCLUSION

The novel commercial FLASH Research Extension system was dosimetrically characterized for pre-clinical FLASH research, and preliminary in vitro results demonstrated the FLASH effect. Given the prevalence of linear accelerators, this new commercial system has the potential to greatly increase the access to FLASH research.

Commissioning and Initial Validation of Commercial Treatment Planning System for the Electron FLASH Research Extension

PURPOSE/OBJECTIVE(S)

The aim of this study was to investigate the feasibility of commissioning the 16 MeV electron FLASH beam in a commercial treatment planning system (TPS) for pre-clinical research purposes. The delivery system consisted of a new commercial solution for which a linear accelerator was modified into a FLASH Research Extension platform. Additionally, preliminary radiation biology results were highlighted to showcase the future use of this system.

MATERIALS/METHODS

To commission a commercial electron Monte Carlo (MC) for dose calculation of a 16 MeV FLASH beam in the TPS, radiochromic film was used to measure the vendor-required beam data, e.g., profiles and percent depth dose (PDD) curves for cone sizes of 6 × 6 cm2, 10 × 10 cm2, and 15 × 15 cm2 as well as an in-air profile for a 40 × 40 cm2 open field (no cone). Once the electron MC beam model was generated, additional measurements were collected for validation and compared against the calculated dose from the TPS. A treatment planning comparison between the newly commissioned FLASH beam and the conventional electron beam was conducted. Specifically, the dose-volume histograms (DVHs) for target volumes and organs at risk were investigated for skin cancer cases previously treated with conventional electron beams. Lastly, the FLASH dose distribution predicted by the electron MC for an in vitro cell study setup was validated with radiochromic film measurements, and initial radiobiology tests were conducted using FLASH and conventional dose-rate electron beams.

RESULTS

The electron MC calculated dose for the 16 MeV electron FLASH beam agreed with measured PDDs within 1% for all field sizes. The beam profile characteristics, such as penumbra, shape, and full width at half maximum, demonstrated good agreement with less than 0.5 mm difference between the TPS and measurements. There were noticeable differences in the profiles of large fields between the FLASH and conventional dose-rate beam models due to the more forward-peaked FLASH beam. For treatment planning, Regarding DVH, the FLASH dose-rate plan provided comparable plan quality to the conventional dose-rate plan, achieving adequate coverage for the target volumes and sparing the healthy organs and tissues. The electron MC dose prediction for the FLASH beam was also found to be in good agreement with the film measurements of the in vitro cell study setup. Furthermore, the FLASH beam was observed to be more effective with a 20 % increase in killing pancreatic cancer cells compared to the conventional dose rate.

CONCLUSION

The study successfully incorporated the 16 MeV electron FLASH Research Extension into the commercial TPS using electron Monte Carlo for dose calculation. This will be valuable for pre-clinical cell and animal studies. This research also enables FLASH treatment planning studies, a key component for the future implementation of FLASH into clinical care. Further research is necessary to incorporate the radiation biology effect of FLASH into the treatment planning system.

Detection of Rickettsia spp. and Bartonella spp. in Ctenocephalides felis fleas from free-ranging crab-eating foxes (Cerdocyon thous)

Fleas are insects with a worldwide distribution that have been implicated in the transmission of several pathogens. The present study aimed to investigate the presence of Rickettsia spp. (Rickettsiales: Rickettsiaceae) and Bartonella spp. (Rhizobiales: Bartonellaceae) in fleas from free-ranging crab-eating foxes Cerdocyon thous (Linnaeus, 1766) (Carnivora: Canidae) from Rio Grande do Sul, southern Brazil. Fleas were collected manually from animals and used for the molecular detection of Rickettsia spp. and Bartonella spp. Twenty-nine C. thous were sampled in six municipalities. Four foxes were parasitized by 10 fleas, all of which were identified as Ctenocephalides felis (Bouché, 1935) (Siphonaptera: Pulicidae). DNA from Rickettsia felis Bouyer et al., 2001 and Rickettsia asembonensis Maina et al., 2016 were found in three and eight fleas, respectively. In four fleas, DNA of Bartonella sp. was identified. Phylogenetic analysis grouped Bartonella sp. together with other genotypes previously reported in C. felis worldwide. The scenario described in the present study highlights a Neotropical canid parasitized by the invasive cosmopolitan cat flea, which in turn, is carrying potentially invasive vector-borne microorganisms. These findings suggest that C. felis is adapted to wild hosts in wilderness areas in southern Brazil, hypothetically exposing the Neotropical fauna to unknown ecological and health disturbances.

Abstract P2-01-12: Detection of circulating cancer stem cells: A novel approach as a predictive marker for breast cancer metastases. This may be especially useful in patients with undetectable circulating epithelial tumor cells

Background: Breast cancer is one of the most common types of cancer in women worldwide. It has been demonstrated that even localized tumors without clinically apparent metastases give rise to circulating epithelial tumor cells (CETCs). Recent studies have provided strong support for the circulating cancer stem cell (cCSC) hypothesis, which suggests that a more aggressive subpopulation of circulating tumor cells are the source of metastatic spread from the primary tumor. Measuring CETCs in blood of patients has emerged as a non-invasive diagnostic procedure for screening patients who may be at high risk for developing metastatic cancers. However, accurate detection of CETCs may provide erroneous results, since CETCs undergoing EMT during metastasis are down-regulated for the expression of epithelial cell markers.

Methods: 26 breast cancer patients were included into the study. The determination of CETCs and cCSC was performed using maintrac® method and tumorsphere forming assay, respectively. Cell viability, surface marker expression and ALDH 1 activity of the cells in the spheres were evaluated by fluorescence scanning microscope.

Results: Sphere formation was observed in 80 % of patients. We found that the number of tumorspheres depended on stage of disease. The number of tumorspheres increased significantly with tumor progression, especially with the presence of metastases. Tumorsphere formation was observed in all metastatic patients (median of 30 tumorspheres/100μl of blood), although only 27% of them had detectable CETCs. Analysis of surface marker expression profile showed that the cells in the spheres had typical phenotype of cancer stem cells. Sphere formation was not observed in healthy subjects (n=20).

Conclusion: There is a high correlation between the numbers of tumorspheres cultured from peripheral blood with clinical stage of disease. This may be an indicator of tumor aggressiveness, especially presence of metastases and may provide clinically useful prognostic information.

Citation Format: Pizon M, Schott D, Pachmann U, Pachmann K. Detection of circulating cancer stem cells: A novel approach as a predictive marker for breast cancer metastases. This may be especially useful in patients with undetectable circulating epithelial tumor cells [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-01-12.

Abstract P3-01-17: PD-L1 expression on circulating epithelial tumor cells (CETCs) correlates with aggressiveness of tumor in breast cancer patients

Background: Strategies to improve the efficacy of the immune system against malignant tumors represent a major innovation focusing on the programmed death-1 receptor (PD-1), with its two ligands PD-L1 and PD-L2. The expression of PD-L1 has been evaluated in a number of different tumor types and can be used as a predictive biomarker for PD-1/PD-L1 checkpoint inhibitor treatment response. We used a non-invasive, real-time liquid biopsy to better characterize PD-L1 expression on circulating epithelial tumor cells (CETCs) in breast cancer patients.

Methods: CETCs were determined from blood of 72 patients suffering from breast cancer. The number of vital CETCs and their expression of PD-L1 was investigated using the maintrac® method.

Results: PD-L1 expressing CETCs were detected in 94.5 % of breast cancer patients. Breast cancer patients with metastatic disease had significantly more PD-L1 positive CETCs as compared to patients without metastasis (median 75% vs. 61.1%; p<0.05). Furthermore, patients with positive lymph node status had significantly more PD-L1 positive CETCs as compared to patients with negative lymph nodes (median 60% vs. 93%, p<0,05). Moreover, we observed a significant heterogeneity in PD-L1 immunostaining intensity across CETCs from the same patients.

Conclusion: Breast cancer patients have detectable CETCs with a high frequency of PD-L1 which correlates with progression of cancer disease. PD-L1 seems to be a major factor in immune evasion and may be a promising target of anticancer therapies. Monitoring the frequency of PD-L1 positive CETCs could reflect individual patient's response to an anti-PD-1/PD-L1 therapy.

Citation Format: Schott D, Pizon M, Pachmann U, Pachmann K. PD-L1 expression on circulating epithelial tumor cells (CETCs) correlates with aggressiveness of tumor in breast cancer patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-01-17.

Upper ankle joint prostheses in haemophilia patients

Secondary arthrosis of the upper ankle joint (talocalcanean joint) is one of the most frequent forms of haemophilic arthropathy. It is a secondary form of arthrosis not only because of chronic synovitis and cartilage injury resulting from chronic recurrent intraarticular bleeds, but also due to the misalignment of the joint and abnormal joint stress. The consequences are manifest even in young patients and finally lead to subtalar joint ankylosis with the biomechanical disorder of foot drop (talipes equinus). In such clinical situations, implantation of a subtalar joint endoprosthesis is a viable alternative to arthrodesis. Case report:A man (age: 52 years), suffering from severe haemophilia A (residual FVIII activity < 1 %), no inhibitor formation. The patient has a history of several years of painful ankylosis of the right ankle joint and minor talipes equinus, and suffers from symptomatic talonavicular arthrosis. Open joint cleansing considerably improved mobility in the upper ankle joint and alleviated the pain in the talonavicular joint. However, the recovered mobility of the arthrotic upper ankle joint also activated the patient’s arthrosis, associated with severe pain. As there was no contraindication to upper ankle joint replacement, a cement-free prosthesis was implanted. Three months after surgery, the patient was mobile, with good foot rolling properties without orthopedic aids, and without pain in his upper joint ankle. Conclusion: In terms of biomechanics an upper ankle joint endoprosthesis is a superior alternative to arthrodesis in haemophilia patients. In order to minimize the complication rate, the treatment of haemophilia patients should be restricted to specially equipped interdisciplinary treatment centers with adequately trained and experienced surgeons as well as haemo -staseologists.

Evaluation of a follow-up program for mild traumatic brain injury in schoolchildren

INTRODUCTION

Mild traumatic brain injury is a common condition in childhood. Although classified as mild, post-concussive symptoms may persist and interfere with daily activities. Because no established guidelines exist with respect to follow-up medical care for these children, there may be a delay in receiving appropriate care. We developed a follow up program to screen for persistent symptoms and if necessary, refer patients for further medical assistance.

METHODS

From July 2010 until December 2013, eligible children aged 4-18 years who presented after sustaining a mild traumatic brain injury were included. All patients received a phone call after 6 weeks. After a period of 3 months, both their schoolteacher and parents were asked to complete in a questionnaire. The results were discussed monthly by a multidisciplinary team.

RESULTS

A total of 305 children were enrolled in our follow-up program. Headache was the most common acute symptom upon presentation (63%). Overall, 19% of all patients had problems, either at 6 weeks or 3 months. 14% of these patients were referred for special care. Most common persistent post-concussive symptoms were headache (32%), cognitive problems (23%) and behavioural problems (16%). After a period of two years, a review of patient charts revealed that all of the problems were resolved.

CONCLUSION

One fifth of the children exhibit post-concussive symptoms after mild traumatic brain injury. Education of patients and caregivers and a follow up visit if needed applied appropriate care at an early stage to minimise physical and mental problems.

Cross Sections for the Exclusive Photon Electroproduction on the Proton and Generalized Parton Distributions

Unpolarized and beam-polarized fourfold cross sections (d^{4}σ/dQ^{2}dx_{B}dtdϕ) for the ep→e^{'}p^{'}γ reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 (Q^{2},x_{B},t) bins over the widest phase space ever explored in the valence-quark region. Several models of generalized parton distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD H, expected to be the dominant contributor to these observables. Through a leading-twist extraction of Compton form factors, these results support the model predictions of a larger nucleon size at lower quark-momentum fraction x_{B}.

Towards a resolution of the proton form factor problem: new electron and positron scattering data

There is a significant discrepancy between the values of the proton electric form factor, G(E)(p), extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of G(E)(p) from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization (ϵ) and momentum transfer (Q(2)) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing ϵ at Q(2)=1.45  GeV(2). This measurement is consistent with the size of the form factor discrepancy at Q(2)≈1.75  GeV(2) and with hadronic calculations including nucleon and Δ intermediate states, which have been shown to resolve the discrepancy up to 2-3  GeV(2).

Longitudinal target-spin asymmetries for deeply virtual compton scattering

A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6 GeV electron beam, a longitudinally polarized proton target, and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for ep→e^{'}p^{'}γ events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q^{2}, x_{B}, t, and ϕ, for 166 four-dimensional bins. In the framework of generalized parton distributions, at leading twist the t dependence of these asymmetries provides insight into the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. These results also bring important and necessary constraints for the existing parametrizations of chiral-even generalized parton distributions.

Strangeness suppression of qq creation observed in exclusive reactions

We measured the ratios of electroproduction cross sections from a proton target for three exclusive meson-baryon final states: ΛK(+), pπ(0), and nπ(+), with the CLAS detector at Jefferson Lab. Using a simple model of quark hadronization, we extract qq creation probabilities for the first time in exclusive two-body production, in which only a single qq pair is created. We observe a sizable suppression of strange quark-antiquark pairs compared to nonstrange pairs, similar to that seen in high-energy production.

Hard two-body photodisintegration of 3He

We have measured cross sections for the γ(3)He → pd reaction at photon energies of 0.4-1.4 GeV and a center-of-mass angle of 90°. We observe dimensional scaling above 0.7 GeV at this center-of-mass angle. This is the first observation of dimensional scaling in the photodisintegration of a nucleus heavier than the deuteron.

Measurement of exclusive π(0) electroproduction structure functions and their relationship to transverse generalized parton distributions

Exclusive π(0) electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in Q(2), x(B), t, and ϕ(π), in the Q(2) range from 1.0 to 4.6  GeV(2), -t up to 2  GeV(2), and x(B) from 0.1 to 0.58. Structure functions σ(T)+ϵσ(L), σ(TT), and σ(LT) were extracted as functions of t for each of 17 combinations of Q(2) and x(B). The data were compared directly with two handbag-based calculations including both longitudinal and transversity generalized parton distributions (GPDs). Inclusion of only longitudinal GPDs very strongly underestimates σ(T)+ϵσ(L) and fails to account for σ(TT) and σ(LT), while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity-flip and helicity nonflip processes. The results confirm that exclusive π(0) electroproduction offers direct experimental access to the transversity GPDs.

Measurement of the neutron F2 structure function via spectator tagging with CLAS

We report on the first measurement of the F(2) structure function of the neutron from the semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward hemisphere. Restricting the momentum of the spectator protons to ≲100 MeV/c and their angles to ≳100° relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The F(2)(n) data collected cover the nucleon-resonance and deep-inelastic regions over a wide range of Bjorken x for 0.65<Q(2)<4.52 GeV(2), with uncertainties from nuclear corrections estimated to be less than a few percent. These measurements provide the first determination of the neutron to proton structure function ratio F(2)(n)/F(2)(p) at 0.2≲x≲0.8 with little uncertainty due to nuclear effects.

[Algorithm for the treatment of the haemophilic arthropathia of the upper ankle joint]

The upper ankle joint is one of the target-joints of the haemophilic patient. Therefore, the secondary arthritis of the upper ankle joint is one of the most frequent forms of haemophilic arthropathy. It is a secondary form of arthritis not only because of chronic synovitis and cartilage injury resulting from chronic recurrent intraarticular bleeds, but also due to the misalignment of the joint and abnormal joint stress. The consequences are manifest even in young patients and finally lead to upper ankle joint arthritis. In such clinical situations, the upper ankle joint-arthroplasty is a viable alternative to arthrodesis. After several years of bleeding of the upper ankle joint many patients with haemophilia suffer from symptomatic arthritis. Open joint cleansing considerably improves mobility in the upper ankle joint and alleviates the pain in the talonavicular joint. However, the recovered mobility of the arthritic upper ankle joint also activates arthritis, associated with severe pain. With no contraindication to upper ankle joint replacement, a cement-free prosthesis can be implanted. Three months after surgery, the patients are mobile, with good foot rolling properties without orthopaedic aids and without pain in the upper joint ankle. Concludion: In terms of biomechanics the upper ankle joint-arthroplasty is a superior alternative to arthrodesis in haemophilia patients. In order to minimize the complication rate, their treatment should be restricted to specially equipped interdisciplinary centers with adequately trained and experienced surgeons as well as haemostaseologists.

Absorption of the ω and ϕ mesons in nuclei

Because of their long lifetimes, the ω and ϕ mesons are the ideal candidates for the study of possible modifications of the in-medium meson-nucleon interaction through their absorption inside the nucleus. During the E01-112 experiment at the Thomas Jefferson National Accelerator Facility, the mesons were photoproduced from 2H, C, Ti, Fe, and Pb targets. This Letter reports the first measurement of the ratio of nuclear transparencies for the e+e- channel. The ratios indicate larger in-medium widths compared with what have been reported in other reaction channels. The absorption of the ω meson is stronger than that reported by the CBELSA-TAPS experiment and cannot be explained by recent theoretical models.

Behandlungsalgorithmus der hämophilen Arthropathie des oberen Sprunggelenkes

The upper ankle joint is one of the targetjoints of the haemophilic patient. Therefore, the secondary arthritis of the upper ankle joint is one of the most frequent forms of haemophilic arthropathy. It is a secondary form of arthritis not only because of chronic synovitis and cartilage injury resulting from chronic recurrent intraarticular bleeds, but also due to the misalignment of the joint and abnormal joint stress. The consequences are manifest even in young patients and finally lead to upper ankle joint arthritis. In such clinical situations, the upper ankle joint-arthroplasty is a viable alternative to arthrodesis. After several years of bleeding of the upper ankle joint many patients with haemophilia suffer from symptomatic arthritis. Open joint cleansing considerably improves mobility in the upper ankle joint and alleviates the pain in the talonavicular joint. However, the recovered mobility of the arthritic upper ankle joint also activates arthritis, associated with severe pain. With no contraindication to upper ankle joint replacement, a cement-free prosthesis can be implanted. Three months after surgery, the patients are mobile, with good foot rolling properties without orthopaedic aids and without pain in the upper joint ankle. Concludion: In terms of biomechanics the upper ankle joint-arthroplasty is a superior alternative to arthrodesis in haemophilia patients. In order to minimize the complication rate, their treatment should be restricted to specially equipped interdisciplinary centers with adequately trained and experienced surgeons as well as haemostaseologists.

[Upper ankle joint prostheses in haemophilia patients]

Secondary arthrosis of the upper ankle joint (talocalcanean joint) is one of the most frequent forms of haemophilic arthropathy. It is a secondary form of arthrosis not only because of chronic synovitis and cartilage injury resulting from chronic recurrent intraarticular bleeds, but also due to the misalignment of the joint and abnormal joint stress. The consequences are manifest even in young patients and finally lead to subtalar joint ankylosis with the biomechanical disorder of foot drop (talipes equinus). In such clinical situations, implantation of a subtalar joint endoprosthesis is a viable alternative to arthrodesis.

CASE REPORT

A man (age: 52 years), suffering from severe haemophilia A (residual FVIII activity < 1 %), no inhibitor formation. The patient has a history of several years of painful ankylosis of the right ankle joint and minor talipes equinus, and suffers from symptomatic talonavicular arthrosis. Open joint cleansing considerably improved mobility in the upper ankle joint and alleviated the pain in the talonavicular joint. However, the recovered mobility of the arthrotic upper ankle joint also activated the patient's arthrosis, associated with severe pain. As there was no contraindication to upper ankle joint replacement, a cement-free prosthesis was implanted. Three months after surgery, the patient was mobile, with good foot rolling properties without orthopedic aids, and without pain in his upper joint ankle.

CONCLUSION

In terms of biomechanics an upper ankle joint endoprosthesis is a superior alternative to arthrodesis in haemophilia patients. In order to minimize the complication rate, the treatment of haemophilia patients should be restricted to specially equipped interdisciplinary treatment centers with adequately trained and experienced surgeons as well as haemostaseologists.

Precise measurement of the neutron magnetic form factor G(M)n in the few-GeV2 region

The neutron elastic magnetic form factor was extracted from quasielastic electron scattering on deuterium over the range Q;{2}=1.0-4.8 GeV2 with the CLAS detector at Jefferson Lab. High precision was achieved with a ratio technique and a simultaneous in situ calibration of the neutron detection efficiency. Neutrons were detected with electromagnetic calorimeters and time-of-flight scintillators at two beam energies. The dipole parametrization gives a good description of the data.

Measurement of direct f0(980) photoproduction on the proton

We report on the results of the first measurement of exclusive f_{0}(980) meson photoproduction on protons for E_{gamma}=3.0-3.8 GeV and -t=0.4-1.0 GeV2. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. The resonance was detected via its decay in the pi;{+}pi;{-} channel by performing a partial wave analysis of the reaction gammap-->ppi;{+}pi;{-}. Clear evidence of the f_{0}(980) meson was found in the interference between P and S waves at M_{pi;{+}pi;{-}} approximately 1 GeV. The S-wave differential cross section integrated in the mass range of the f_{0}(980) was found to be a factor of about 50 smaller than the cross section for the rho meson. This is the first time the f_{0}(980) meson has been measured in a photoproduction experiment.

CD34(+) CD38(-) and CD34(+) HLA-DR(-) cells in BM stem cell grafts correlate with short-term engraftment but have no influence on long-term hematopoietic reconstitution after autologous transplantation

BACKGROUND

Prior studies have demonstrated that relatively immature hematopoietic stem cells, including CD34(+) CD38(-) and CD34(+) HLA-DR(-) subsets, correlate with short-term hematopoietic reconstruction (SHR) after transplantation. The aim of this study was to investigate whether these immature CD34(+) subsets also correlate with long-term hematopoietic reconstitution (LHR) in recipients of ABMT.

METHODS

We examined stem cell grafts from 58 patients with B-cell lymphoma or CLL who underwent ABMT after myeloablative conditioning. We determined whether total mononuclear cell dose (MNC), colony-forming unit-granulocyte-monocyte (CFU-GM), CD34(+) cell dose and CD34(+) cell subsets (CD34(+) CD38(-) and CD34(+) HLA-DR(-) were associated with SHR and/or LHR. Time to neutrophil engraftment (TNE) and time to platelet engraftment (TPE) were used to measure SHR, while platelet counts at day 100 and 1 year post-ABMT were used as indicators for LHR.

RESULTS AND DISCUSSION

CD34(+) cell dose and CD34(+) cell subsets were significantly associated with SHR. However, at day 100 and 1 year post-transplant only total CD34(+) cell dose was associated with LHR. The association of total CD34(+) cell dose with LHR persisted after adjusting for age, sex and disease. None of the CD34(+) cell subsets analyzed showed evidence of significant association with LHR.

Prospective randomized trial to evaluate two delayed granulocyte colony stimulating factor administration schedules after high-dose cytarabine therapy in adult patients with acute lymphoblastic leukemia

In acute lymphoblastic leukemia (ALL), treatment with granulocyte colony stimulating factor (G-CSF) during remission induction shortens granulocytopenia and may decrease morbidity due to infections. However, the optimal timing of G-CSF administration after chemotherapy is not known. In a prospective randomized multi-center study, adult ALL patients were treated with high-dose ARA-C [HDAC, 3 g/m(2) bid (1 g/m(2) bid for T-ALL) days 1-4] and mitoxantrone (MI 10 mg/m(2) days 3-5). They were randomized to receive recombinant human G-CSF (Lenograstim) 263 micro g/day SC starting either from day 12 (Group 1) or day 17 (Group 2). Fifty-five patients (41 male, 14 female) with a median age of 34 years (range: 18-55 years) were enrolled into the study; 50 patients were evaluable. The median duration of neutropenia <500/ micro l after HDAC/MI was 12 days (range: 7-22 days) in the early G-CSF Group 1 and also 12 days (range: 4-22 days) in the late G-CSF Group 2; this was shorter than in the historical control group (15 days, range: 4-43 days, n=46) where the patients received identical cytotoxic treatment without G-CSF. Seventeen infections were observed in 14 patients in Group 1 (47%) and 13 infections in 10 patients in Group 2 (50%) compared to 27 infections in 49 patients of the historical control (54%). In Group 1, the patients received a median of 11 injections with G-CSF (range: 7-22) compared to 7 injections (range: 4-19) in Group 2. The total administered dose of G-CSF in Group 2 was significantly reduced by 40% ( P<0.0001). The delayed start of G-CSF after HDAC/MI in ALL achieves the same clinical benefit compared to the earlier initiation of G-CSF. The reduction of treatment costs by reducing the total G-CSF dose may be important in future treatment with this hematopoietic growth factor.

GC-MS analysis of hydrophobic root exudates of sorghum and implications on the parasitic plant Striga asiatica

Striga asiatica is a parasitic angiosperm that responds to germination stimulants produced by host plants, including many grasses. GC-MS analyses of hydrophobic root exudates of sorghum revealed the root exudates to be composed of fatty acids, resorcinol, and a series of structurally related hydroquinones, three of which were previously unknown. High yields of resorcinol and the hydroquinone series were detected in sorghum. At least one of the hydroquinones induces germination in Striga, and the resorcinol is thought to stabilize the hydroquinones in the soil. The previously unknown series of hydroquinones offers insight into the possible biosynthesis of the components of the exudate and their possible importance in initiating Striga germination.

Rehospitalization among home healthcare patients: results of a prospective study

Reduction in rehospitalization is an outcome measure used to evaluate home care services, especially in Outcome Based Quality Management using OASIS data; however, practitioners and managers must carefully analyze the reasons patients return to the hospital. This study examines events leading to rehospitalization of patients with CHF, whether it is possible to determine upon admission which patients are at risk, and whether the readmissions were necessary and/or preventable. Among the study's important findings are that half of the patients developed a new problem that required the rehospitalization. This and other research outcomes should be considered when analyzing adverse event reports.

Fibrinogen heterogeneity in homozygous plasminogen deficiency type I: further evidence that plasmin is not involved in formation of LMW- and LMW'-fibrinogen

Human plasma fibrinogen is heterogeneous in SDS-polyacrylamide gel electrophoresis and other methods for separation of proteins by molecular size. A high molecular weight fraction (HMW-fibrinogen, 340 kD) contributes approximately 50% of total fibrinogen antigen. Low molecular weight fibrinogen (LMW-fibrinogen, 300 kD) adds another 40%. The residual amount is LMW'-fibrinogen with a molecular weight of 280 kD, and a small amount of very high molecular weight fibrinogen (Fib420), the product of alternative splicing of the A alpha-chain genetic information, resulting in an extended A alpha-chain C-terminus. Fibrinogen was detected by specific immunostaining of nonreduced SDS-PAGE gel immunoblots with antibodies against fibrinopeptide A. Using densitometric scans of the immunoblots we found a ratio of HMW-, LMW- and LMW'-fibrinogen in a patient with homozygous plasminogen deficiency that was similar to the ratio found in immunoblots of plasma from healthy blood donors. Treatment with plasminogen concentrate resulted in a slight decrease of the proportion of HMW-fibrinogen, followed by an increase to 78%. The LMW'-fibrinogen band gained intensity initially, increasing to 11.9% of fibrinogen antigen 6 h after starting plasminogen infusion, but then dropped to levels below detection limit of the immunoblotting assay. LMW-fibrinogen remained constant during the initial 72 h of plasminogen treatment, then dropping to values in the range of 22-25% afterwards. The proportion of HMW-, LMW-, and LMW'-fibrinogen again reached the initial levels two weeks after starting treatment with plasminogen concentrate. We conclude that plasminogen is not involved in the limited proteolysis leading to formation of LMW-fibrinogen and LMW'-fibrinogen in the absence of a generalized fibrinolytic condition. Fibrinolytic activation may lead to the formation of fibrinogen degradation product X, which appears in a similar position as LMW'-fibrinogen in SDS-PAGE.