Prognostic value of deep learning-derived body composition in advanced pancreatic cancer-a retrospective multicenter study

BACKGROUND

Despite the prognostic relevance of cachexia in pancreatic cancer, individual body composition has not been routinely integrated into treatment planning. In this multicenter study, we investigated the prognostic value of sarcopenia and myosteatosis automatically extracted from routine computed tomography (CT) scans of patients with advanced pancreatic ductal adenocarcinoma (PDAC).

PATIENTS AND METHODS

We retrospectively analyzed clinical imaging data of 601 patients from three German cancer centers. We applied a deep learning approach to assess sarcopenia by the abdominal muscle-to-bone ratio (MBR) and myosteatosis by the ratio of abdominal inter- and intramuscular fat to muscle volume. In the pooled cohort, univariable and multivariable analyses were carried out to analyze the association between body composition markers and overall survival (OS). We analyzed the relationship between body composition markers and laboratory values during the first year of therapy in a subgroup using linear regression analysis adjusted for age, sex, and American Joint Committee on Cancer (AJCC) stage.

RESULTS

Deep learning-derived MBR [hazard ratio (HR) 0.60, 95% confidence interval (CI) 0.47-0.77, P < 0.005] and myosteatosis (HR 3.73, 95% CI 1.66-8.39, P < 0.005) were significantly associated with OS in univariable analysis. In multivariable analysis, MBR (P = 0.019) and myosteatosis (P = 0.02) were associated with OS independent of age, sex, and AJCC stage. In a subgroup, MBR and myosteatosis were associated with albumin and C-reactive protein levels after initiation of therapy. Additionally, MBR was also associated with hemoglobin and total protein levels.

CONCLUSIONS

Our work demonstrates that deep learning can be applied across cancer centers to automatically assess sarcopenia and myosteatosis from routine CT scans. We highlight the prognostic role of our proposed markers and show a strong relationship with protein levels, inflammation, and anemia. In clinical practice, automated body composition analysis holds the potential to further personalize cancer treatment.

Scintillation and radioluminescence mechanism in β-Ga2O3 semiconducting single crystals

In this paper, we present the results of experiments on samples of β-Ga2O3 single crystals under a project aimed at assessing and improving the scintillation performance of this material by studying scintillation and radioluminescence mechanism and its limitations. In addition to standard experiments, such as scintillation light yields and time profiles, radio-, and thermoluminescence, we developed and tested a new and promising two-beam experiment, in which a sample is excited by an X-ray beam and additionally stimulated by an IR laser diode. Fe and Mg doping compensate for the inherent n-type conductivity of β-Ga2O3 to obtain semi-insulating single crystals for large-area substrates and wafers. At the same time, residual Fe and Ir are ubiquitous uncontrolled impurities leached from the Ir crucibles used to grow large bulk crystals by the Czochralski method. For these experiments, we selected four samples cut from the Czochralski grown 2-cm diameter β-Ga2O3 single crystal boules; one with a reduced Fe content, two unintentionally Fe- and Ir-doped (UID) with lower and higher Fe content, and one doped with Mg. We find that steady-state radioluminescence spectra measured at temperatures between 10 and 350 K are dominated by the UV emission peaking at about 350-370 nm. Unfortunately, even for the best sample with a reduced Fe-content, the intensity of this emission drops precipitously with the temperature down to about 10 % at 300 K. From the two-beam experiments, we conclude that recombination via inadvertent Fe impurity involving three charge states (2+, 3+, and 4+) may reduce a steady-state UV emission of β-Ga2O3 under X-ray excitation by as much as 60-70 %, one-third to one-half of which is due to the recombination (specific for Fe-doped β-Ga2O3) involving the 4+ and 3+ charge states of Fe and the remaining 50-70 % being due to a more familiar route typical of other oxides, involving the 2+ and 3+ charge states of Fe. These losses are at higher temperatures enhanced by a thermally activated redistribution of self-trapped holes (STHs). In addition, the trapping of electrons by Fe and holes by Mg, Fe, and Ir may be responsible for scintillation light loss and reduction of the zero-time amplitude essential for the fast timing scintillation applications. Despite indirect evidence of competitive recombination in β-Ga2O3 involving a deep Ir3+/4+ donor level, we could not quantitatively assess losses of the UV steady state radioluminescence light due to the inadvertent Ir impurity.

Dynamic complex opto-magnetic holography

Despite recent significant progress in real-time, large-area computer-generated holography, its memory requirements and computational loads will be hard to tackle for several decades to come with the current paradigm based on a priori calculations and bit-plane writing to a spatial light modulator. Here we experimentally demonstrate a holistic approach to serial computation and repeatable writing of computer-generated dynamic holograms without Fourier transform, using minimal amounts of computer memory. We use the ultrafast opto-magnetic recording of holographic patterns in a ferrimagnetic film with femtosecond laser pulses, driven by the on-the-fly hardware computation of a single holographic point. The intensity-threshold nature of the magnetic medium allows sub-diffraction-limited, point-by-point toggling of arbitrarily localized magnetic spots on the sample, according to the proposed circular detour-phase encoding, providing complex modulation and symmetrical suppression of upper diffractive orders and conjugated terms in holographically reconstructed 3-D images.

Holography recreates both the amplitude and wave front of a three dimensional object, meaning that the observer perceives the image in the nearly same way as they would the true object. Creating such holographic images is challenging computationally, and requires extremely fast display update. Here, the authors combine a fast memoryless computation algorithm with the ultra-rapid writing based on all-optical switching of a ferrimagnetic film.

AB0796 Quantitative bone marrow lesion characterization at the sacroiliac joint with T1-mapping

Background

Conventional magnetic resonance imaging (MRI) uses T1-weighted and short-tau inversion recovery (STIR) sequences to characterize bone marrow lesions in axial spondyloarthritis. However, quantification is restricted to the extent of marrow lesions because signal intensities are highly variable within and across patients and scanners. Furthermore, some marrow lesions are less visible in MRI and need further characterization with computed tomography (CT), e.g. sclerosis. Quantitative MRI in form of mapping sequences might help to better characterize bone marrow lesions.

Objectives

To evaluate the performance of T1-mapping for differentiating different bone marrow lesions at the sacroiliac joints in patients with suspected axial spondyloarthritis.

Methods

Sixty-two patients (mean age 41±12.5; thirty-two were finally diagnosed with axial spondyloarthritis and 30 with another condition) underwent CT and MRI of the sacroiliac joints. Besides standard oblique coronal T1 and STIR sequences a T1-mapping sequence (Modified Look-Locker Inversion Recovery) was added to the protocol. Bone marrow lesions (maximum 4 lesions per patient, 1 lesion of the same type per joint) were characterized by an expert radiologist into four groups, namely sclerosis (lesion type (LT) 1), osteitis (LT2), fat lesion (LT3) and mixed marrow lesions (LTm). Relaxation times on T1-maps were compared using Kruskal-Wallis test correcting for multiple comparisons and correlated to quantitative measures from conventional MRI sequences and CT.

Results

119 lesions were selected (LT1: 38, LT2: 27, LT3: 40; LTm: 14). T1-map showed highly significant differences between LT1-3 with the lowest values for sclerosis (1522±227 ms), followed by osteitis (1906±82 ms) and fat lesions (2391±200 ms); p<0.0005. However, mixed lesions showed a broad distribution of values (1869±670), irrespective of their characteristics. T1-map correlated to a high degree with conventional T1-values (r = 0.74) and Hounsfield units in CT (r = -0.69) with p < 0.0001, respectively, but not with STIR (p = 0.8).

Conclusion

T1-Mapping allows for accurately characterizing lesions at the sacroiliac joint in patients with suspected axial spondyloarthritis and, thus, may combine information from two conventional sequences and CT into one in the future while providing superior capacity for quantification. However, in our study mixed lesions and inhomogeneous bone marrow remained problematic. Thus, further sequence development is needed before its implementation in clinical routine.

Figure 1.

T1-mapping values of the different lesions, LT1: Sclerosis, LT2: Osteitis, LT3: Fat lesion, LTm: Mixed lesion. Differences are highly significant, which allows T1-mapping to characterize those different lesions in one sequence.

Disclosure of Interests

Torsten Diekhoff Speakers bureau: Novartis, Eli Lilly, MSD, Canon MS, Consultant of: Novartis, Dominik Deppe: None declared, Denis Poddubnyy: None declared, Katharina Ziegeler: None declared, Fabian Proft: None declared, Kay-Geert Hermann: None declared, Mikhail Protopopov: None declared, Felix Radny: None declared, Marcus Makowski: None declared

OP0152 A DEEP LEARNING FRAMEWORK FOR MRI DETECTION OF ACTIVE INFLAMMATORY AND STRUCTURAL CHANGES IN THE SACROILIAC JOINT CONSISTENT WITH AXIAL SPONDYLOARTHRITIS: AN INTERNATIONAL COLLABORATIVE STUDY

Background

Magnetic resonance tomography (MRI) plays a key role in the early diagnosis of axial spondyloarthritis (axSpA). However, the detection of changes indicative of axSpA requires specific expertise, which poses a challenge to non-specialized centers. Deep learning (an advanced machine learning method) based on training an artificial neural network may facilitate and support diagnostics in clinical practice.

Objectives

To create a reliable deep learning tool for the detection of active inflammatory and structural changes indicative of axSpA on MRI of sacroiliac joints.

Methods

In this study, MRIs of sacroiliac joints from 477 patients from four cohorts (GESPIC-AS, GESPIC-Crohn, GESPIC-Uveitis and OptiRef comprising 266 patients with and 211 without axSpA) were used to develop a deep learning framework (randomly divided into training, n=404, and validation, n=73, datasets). MRIs from the ASAS cohort (n=116) were used for independent testing (test dataset). Each examination in the training/validation dataset was evaluated for the presence of active inflammatory and structural changes indicative of SpA by six experienced, trained and calibrated readers and by seven expert readers in the test dataset. The presence of the changes was defined as the majority vote amongst readers. Discordant cases in the training/validation dataset underwent consensus reading. In addition, the test dataset was evaluated by three radiologists not specifically trained in SpA. Diagnostic performance was evaluated using the area under the receiver operating characteristic curve (AUC), accuracy, sensitivity and specificity.

Results

The prevalence of positive imaging findings for active inflammatory/structural changes indicative of axSpA was 41%/51% in the training/validation dataset and 22%/22% in the test dataset. The model for the detection of active inflammatory changes showed an AUC of 0.91 (0.83 – 0.97) – Figure 1 – and an accuracy of 84% on the validation dataset; the corresponding sensitivity and specificity were 96% and 76%, respectively. Despite a substantially lower prevalence of active inflammatory changes in the test dataset, the model showed good generalization with an AUC of 0.91 (0.84−0.97) and an accuracy of 75%; the sensitivity and specificity were 88% and 71%, respectively. The model demonstrated a similar performance on the validation and test datasets for the detection of active inflammatory changes fulfilling the ASAS definition. The model for the detection of structural changes indicative of axSpA showed good performance on the validation dataset with an AUC of 0.90 (0.82-0.96) for the detection of structural changes and an overall accuracy of 85%. The associated sensitivity and specificity were 95% and 75%, respectively. The model showed reasonable generalization to new data with an AUC of 0.89 (0.81−0.96) and an accuracy of 79%; the sensitivity and specificity were 85% and 78%, respectively. Overall, the model performed close to the individual human experts - Figure 1.

Conclusion

The developed framework allowed the detection of active inflammatory and structural changes indicative of axSpA on MRI. This approach may be used as an assistant tool in the diagnostic workflow.

Acknowledgements

GESPIC-AS has been financially supported by the German Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung - BMBF). GESPIC-Crohn has been supported by the Clinical Research Unit grant from the Berlin Institute of Health (BIH). GESPIC-Uveitis has been supported by a research grant from AbbVie. OptiRef has been supported by a research grant from Novartis. The Assessment of Spondyloarthritis International Society (ASAS) has supported the project with a research grant and provided access to the MRI images of the ASAS calssifiaction cohort.

We want to thank colleagues who performed annotation of the images from the ASAS classification cohort: Pedro Machado, Mikkel Ostergaard, Suzanne Juhl Pedersen, Ulrich Weber. Further, we thank Torsten Karge for the development of the MRI reading interface for GESPIC and OptiRef images, Joel Paschke for development of the scoring interface for ASAS images.

LCA is grateful for her participation in the BIH Charité–Junior Clinician and Clinician Scientist Program and KKB is grateful for his participation in the BIH Charité Digital Clinician Scientist Program all funded by the Charité–Universitätsmedizin Berlin and the Berlin Institute of Health. JR is grateful for her participation in the BIH Charité–Junior Clinician and Clinician Scientist Program.

Disclosure of Interests

None declared

Prostate Cancer Nodal Staging: Using Deep Learning to Predict 68Ga-PSMA-Positivity from CT Imaging Alone

Lymphatic spread determines treatment decisions in prostate cancer (PCa) patients. 68Ga-PSMA-PET/CT can be performed, although cost remains high and availability is limited. Therefore, computed tomography (CT) continues to be the most used modality for PCa staging. We assessed if convolutional neural networks (CNNs) can be trained to determine 68Ga-PSMA-PET/CT-lymph node status from CT alone. In 549 patients with 68Ga-PSMA PET/CT imaging, 2616 lymph nodes were segmented. Using PET as a reference standard, three CNNs were trained. Training sets balanced for infiltration status, lymph node location and additionally, masked images, were used for training. CNNs were evaluated using a separate test set and performance was compared to radiologists' assessments and random forest classifiers. Heatmaps maps were used to identify the performance determining image regions. The CNNs performed with an Area-Under-the-Curve of 0.95 (status balanced) and 0.86 (location balanced, masked), compared to an AUC of 0.81 of experienced radiologists. Interestingly, CNNs used anatomical surroundings to increase their performance, "learning" the infiltration probabilities of anatomical locations. In conclusion, CNNs have the potential to build a well performing CT-based biomarker for lymph node metastases in PCa, with different types of class balancing strongly affecting CNN performance.

P5249Comprehensive invasive and non-invasive assessment of coronary artery lesions with and without hemodynamic significance

Background

There is limited knowledge about specific morphological parameters beyond the degree of stenosis to further characterize hemodynamically relevant coronary lesions.

Objective

The goal of this study was to identify certain morphological or molecular characteristics that distinguish hemodynamically significant from non-significant coronary lesions using various invasive and non-invasive measures.

Methods

This clinical study included patients with symptoms suggestive of CAD who underwent native T1-weighted CMR and gadofosveset-enhanced CMR as well as invasive coronary angiography between 2015 and 2016. OCT of the culprit vessel to determine the plaque type was performed in a subset of patients. Functional relevance of all lesions was examined using quantitative flow reserve (QFR-Angio). Hemodynamically significant lesions were defined as lesions with a QFR <0.8. Signal intensity (contrast-to-noise ratios; CNRs) on native T1-weighted CMR and gadofosveset-enhanced CMR was defined as a measure for intraplaque hemorrhage and endothelial permeability respectively.

Results

Overall 13 patients (n=28 coronary segments) were included, whose invasive coronary angiograms projections were eligible for QFR analysis. Segments containing lesions with a QFR <0.8 (n=9) were associated with significantly higher signal enhancement on Gadofosveset-enhanced CMR as compared to segments containing a hemodynamically non-relevant lesions (lesion-QFR>0.8; n=19) (7.0±4.9 vs. 3.0±2.6; p=0.02). No differences in signal enhancement were seen on native T1-weighted CMR (2.1±4.3 vs. 3.3±4.1; p=0.24). 66,7% (4 out of 6) of all vulnerable plaque and 33.3% (2 out of 6) of all non-vulnerable plaque (fibroatheroma) as assessed by OCT were hemodynamically significant lesions.

Conclusion

The findings of this small feasibility study suggest that hemodynamically significant lesions are more advanced and associated with a higher grade of endothelial permeability while the presence of intraplaque hemorrhage may not be associated with hemodynamically relevant coronary lesions.

Orthopaedic manifestations of pseudoachondroplasia

PURPOSE

In 1959, Maroteaux and Lamy initially designated pseudoachondroplasia as a distinct dysplasia different from achondroplasia the most common form of skeletal dysplasia. Pseudoachondroplasia is caused by a mutation in the collagen oligomeric matrix protein gene (COMP) gene on chromosome 19p13.1-p12 encoding the COMP. The COMP gene mutations result in rendering the articular and growth plate cartilages incapable of withstanding routine biomechanical loads with resultant deformity of the joints. The purpose of the study was to characterize the typical orthopaedic findings in pseudoachondroplasia.

METHODS

The charts and radiographs of 141 patients with pseudoachondroplasia were analyzed. This cohort, to our knowledge, represents the largest group of patients describing the typical orthopaedic manifestations of pseudoachondroplasia.

RESULTS

Patients with pseudoachondroplasia have normal craniofacial appearance with normal intelligence. Short stature is not present at birth and generally appears by two to four years of age. The condition is a form of spondyloepiphyseal dysplasia and the long bones are characterized by dysplastic changes in the epiphysis, metaphysis and vertebral bodies. Radiographically the long bones have altered the appearance and structure of the epiphyses with small irregularly formed or fragmented epiphyses or flattening. The metaphyseal regions of the long bones show flaring, widening or 'trumpeting'. The cervical (89%) and thoracic and lumbar vertebrae show either platyspondyly, ovoid, 'cod-fish' deformity or anterior 'beaking'. Kyphosis (28%), scoliosis (58%) and lumbar lordosis (100%) are commonly seen. The femoral head and acetabulum are severely dysplastic (100%). The knees show either genu valgum (22%), genu varum (56%) or 'windswept' deformity (22%).

CONCLUSION

Most commonly these distortions of the appendicular and the axial skeleton lead to premature arthritis particularly of the hips and often the knees not uncommonly in the 20- to 30-year-old age group.

LEVEL OF EVIDENCE

III.

Imaging divertor strike point splitting in RMP ELM suppression experiments in the DIII-D tokamak

Fast visible imaging of the lower divertor from above is used to study the structure and dynamics of lobes induced by resonant magnetic perturbations (RMPs) in Edge-Localized Mode (ELM) suppression experiments in DIII-D. The best compromise between the amount of light and sharp imaging was obtained using emission at 601 nm from Fulcher band molecular deuterium. Multiple spatially resolved peaks in the D₂ emission, taken as a proxy for the particle flux, are readily resolved during RMPs, in contrast to the heat flux measured by infrared cameras, which shows little spatial structure in ITER-like conditions. The 25 mm objective lens provides high spatial resolution (2-4 mm/pixel) from the centerpost to the outer shelf over 40° toroidally that overlaps the field of view of the IRTV that measures the divertor heat flux, allowing direct comparison in non-axisymmetric discharges. The image is coupled to a Phantom 7.3 camera using a Schott wound fiber bundle, providing high temporal resolution that allows the lobe dynamics to be resolved between ELMs and across ELM suppression onset. These measurements are used to study the heat and particle flux in 3D magnetic fields and to validate models for the plasma response to RMPs.

Lymph kinetics with technetium-99m labeled radiopharmaceuticals

Aim of this study was to characterize suitable technetium- 99m labeled tracers for lymphoscintigraphy by comparative animal tests. Animals, methods: To evaluate the influence of the particle size and the organ tracer-uptake on lymphtransport animal experiments were performed on six different agents (including one control group). Activity distributions were examined in Sprague-Dawley-rats by lymphoscintigraphy; the maximum uptake (count-rate) of the whole body and in lymph nodes were analyzed by regions- of-interest-technique, respectively. Additionally, for characterization of lymphatic and extralymphatic traceruptake an intra-individual relative count-rate ratio of the liver, lung, kidneys, and spleen has been calculated following organ extraction. Results: Organ specific differences of distribution were clearly demonstrated. Our results indicate that the kinetics of lymphoscintigraphic 99mTc-bound agents substantially depends on particle size. Reliable transport from the interstitium to initial lymph vessels and lymph node uptake suggested for tracers suited for lymphoscintigraphy a median size of about <100 nm. Conclusion: Our data could improve standardization of diagnostic methods and lead to an objective consideration of therapeutic procedures.

Digital breast tomosynthesis versus full-field digital mammography-Which modality provides more accurate prediction of margin status in specimen radiography?

OBJECTIVES

To evaluate the reliability of tumor margin assessment in specimen radiography (SR) using digital breast tomosynthesis (DBT) and full-field digital mammography (FFDM) in comparison to postoperative histopathology margin status as the gold standard.

METHODS

After ethics committee approval, 102 consecutive patients who underwent breast conservative surgery for nonpalpable proven breast cancer were prospectively included. All patients underwent ultrasound/mammography-guided wire localization of their lesions. After excision, each specimen was marked for orientation and imaged using FFDM and DBT. Two blinded radiologists (R1, R2) independently analyzed images acquired with both modalities. Readers identified in which direction the lesion was closest to the specimen margin and to measure the margin width. Their findings were compared with the final histopathological analysis. True positive margin status was defined as a margin measuring <1mm for invasive cancer and 5mm for ductal carcinoma in situ (DCIS) at imaging and pathology.

RESULTS

For FFDM, correct margin direction was identified in 45 cases (44%) by R1 and in 37 cases (36%) by R2. For DBT, 69 cases (68%) were correctly identified by R1 and 70 cases (69%) by R2. Overall accuracy was 40% for FFDM and 69% for DBT; the difference was statistically significant (p<0.0001). Sensitivity in terms of correct assessment of margin status was significantly better for DBT than FFDM (77% versus 62%).

CONCLUSION

SR using DBT is significantly superior to FFDM regarding identification of the closest margin and sensitivity in assessment of margin status.

The impact of various protective tools on the dose reduction in the eye lens in an interventional cardiology-clinical study

The aim of the study was to check, in clinical practice, the potential for the dose reduction of lead eyewear and a ceiling-suspended shield used to protect the eye lens of physicians working in interventional cardiology. To this end, for the lead eyewear, the dose reduction factors were derived to correct the readings from a dosimeter used routinely outside the glasses. Four types of lead eyewear with attached loose thermoluminescent dosimeters and EYE-D dosimeters were worn by physicians in two clinical centres, for two-month periods, during coronary angiography (CA), percutaneous coronary intervention (PCI), and pacemaker procedures. In order to analyse, separately, how a ceiling-suspended lead screen absorbs the scattered radiation, a series of measurements was carried out during single CA/PCI procedures performed with and without the protection. The lead eyewear may reduce the doses to the eye closest to the x-ray tube by a factor between 1.1 and 3.4, depending on its model and the physician's position. The effectiveness of the eyewear may, however, vary-even for the same model and physician-almost twofold between different working periods. The ceiling-suspended shield decreases the doses in clinical practice by a factor of 2.3. The annual eye lens doses without the eyewear estimated from routine measurements are high-above or close to the new eye lens dose limit established by the recent EU Basic Safety Standards, even though the ceiling-suspended shield was used. Therefore, to comply with the new dose limit that is set in the Directive, protection of the eyes of physicians with high workloads might require the use of both the eyewear and the ceiling-suspended shield.

High order kinoforms as a broadband achromatic diffractive optics for terahertz beams

We discuss thin optical structures that allow chromatic aberrations to be avoided in the THz domain. The paper contains the theoretical considerations, computer modeling and experimental evaluation of the high order kinoform diffractive elements in the THz range. According to the obtained results application of the high order kinoforms enables broadband operation in the THz range.

Modeling of the optical system illuminated by quasi-monochromatic spatially incoherent light: new numerical approach

This Letter presents a new method for modeling of complex optical setups illuminated by quasi monochromatic spatially incoherent light. The algorithm provides better performance and quality than other modeling methods both for isoplanatic and nonisoplanatic systems. The algorithm maintains energy relations, image orientation, and magnification of the system. Computer modeling and experimental results are presented.

Pentapeptides containing two dehydrophenylalanine residues--synthesis, structural studies and evaluation of their activity towards cathepsin C

Synthesis, structural and biological studies of pentapeptides containing two DeltaPhe residues (Z and E isomers) in position 2 and 4 in peptide chain were performed. All the investigated peptides adopted bent conformation and majority of them could exist as two different conformers in solution. Only pentapeptides, containing free N-termini appeared to act as weak inhibitors of cathepsin C with the slow-binding, competitive mechanism of inhibition, free acids being bound slightly better than their methyl esters. Results of molecular modeling suggested significant difference between peptides, depending of the type of amino acid residue in position 5 in peptide chain. Dehydropeptides containing Gly residue in this position may act as competitive slow-reacting substrates and therefore exhibit inhibitory-like properties.

Heme oxygenase-1 protects tumor cells against photodynamic therapy-mediated cytotoxicity

Photodynamic therapy is a promising antitumor treatment modality approved for the management of both early and advanced tumors. The mechanisms of its antitumor action include generation of singlet oxygen and reactive oxygen species that directly damage tumor cells and tumor vasculature. A number of mechanisms seem to be involved in the protective responses to PDT that include activation of transcription factors, heat shock proteins, antioxidant enzymes and antiapoptotic pathways. Elucidation of these mechanisms might result in the design of more effective combination strategies to improve the antitumor efficacy of PDT. Using DNA microarray analysis to identify stress-related genes induced by Photofrin-mediated PDT in colon adenocarcinoma C-26 cells, we observed a marked induction of heme oxygenase-1 (HO-1). Induction of HO-1 with hemin or stable transfection of C-26 with a plasmid vector encoding HO-1 increased resistance of tumor cells to PDT-mediated cytotoxicity. On the other hand, zinc (II) protoporphyrin IX, an HO-1 inhibitor, markedly augmented PDT-mediated cytotoxicity towards C-26 and human ovarian carcinoma MDAH2774 cells. Neither bilirubin, biliverdin nor carbon monoxide, direct products of HO-1 catalysed heme degradation, was responsible for cytoprotection. Importantly, desferrioxamine, a potent iron chelator significantly potentiated cytotoxic effects of PDT. Altogether our results indicate that HO-1 is involved in an important protective mechanism against PDT-mediated phototoxicity and administration of HO-1 inhibitors might be an effective way to potentiate antitumor effectiveness of PDT.

[Lymph kinetics with technetium-99m labeled radiopharmaceuticals. Animal studies]

Aim of this study was to characterize suitable technetium-99m labeled tracers for lymphoscintigraphy by comparative animal tests.

ANIMALS, METHODS

To evaluate the influence of the particle size and the organ tracer-uptake on lymphtransport animal experiments were performed on six different agents (including one control group). Activity distributions were examined in Sprague-Dawley-rats by lymphoscintigraphy; the maximum uptake (count-rate) of the whole body and in lymph nodes were analyzed by regions-of-interest-technique, respectively. Additionally, for characterization of lymphatic and extralymphatic traceruptake an intra-individual relative count-rate ratio of the liver, lung, kidneys, and spleen has been calculated following organ extraction.

RESULTS

Organ specific differences of distribution were clearly demonstrated. Our results indicate that the kinetics of lymphoscintigraphic (99m)Tc-bound agents substantially depends on particle size. Reliable transport from the interstitium to initial lymph vessels and lymph node uptake suggested for tracers suited for lymphoscintigraphy a median size of about <100 nm.

CONCLUSION

Our data could improve standardization of diagnostic methods and lead to an objective consideration of therapeutic procedures.

Physics-based protein-structure prediction using a hierarchical protocol based on the UNRES force field: assessment in two blind tests

Recent improvements in the protein-structure prediction method developed in our laboratory, based on the thermodynamic hypothesis, are described. The conformational space is searched extensively at the united-residue level by using our physics-based UNRES energy function and the conformational space annealing method of global optimization. The lowest-energy coarse-grained structures are then converted to an all-atom representation and energy-minimized with the ECEPP/3 force field. The procedure was assessed in two recent blind tests of protein-structure prediction. During the first blind test, we predicted large fragments of alpha and alpha+beta proteins [60-70 residues with C(alpha) rms deviation (rmsd) <6 A]. However, for alpha+beta proteins, significant topological errors occurred despite low rmsd values. In the second exercise, we predicted whole structures of five proteins (two alpha and three alpha+beta, with sizes of 53-235 residues) with remarkably good accuracy. In particular, for the genomic target TM0487 (a 102-residue alpha+beta protein from Thermotoga maritima), we predicted the complete, topologically correct structure with 7.3-A C(alpha) rmsd. So far this protein is the largest alpha+beta protein predicted based solely on the amino acid sequence and a physics-based potential-energy function and search procedure. For target T0198, a phosphate transport system regulator PhoU from T. maritima (a 235-residue mainly alpha-helical protein), we predicted the topology of the whole six-helix bundle correctly within 8 A rmsd, except the 32 C-terminal residues, most of which form a beta-hairpin. These and other examples described in this work demonstrate significant progress in physics-based protein-structure prediction.

Butyric acid enhances in vivo expression of hTNF-alpha in transduced melanoma cell line

Butyric acid (NaBut) and its derivatives are well-known agents eliciting tumor cell differentiation and apoptosis. In experimental models, NaBut is also used to enhance the efficacy of viral vectors. With the use of B78 murine melanoma cells transduced with the retroviral vector containing human tumor necrosis factor alpha (hTNF-alpha) gene, we investigated the ability of NaBut to increase the cytokine expression. We observed an increase in hTNF-alpha expression in vitro after incubation with NaBut. We also describe that the NaBut pro-drug tributyrin is able to increase hTNF-alpha expression in transduced B78 cells in a tumor vaccination model in mice. This observation strongly suggests a novel potential role for NaBut and its derivatives in tumor therapy. It could be used not only as a therapeutic directly acting on tumor cells but, in parallel, as a genetic vaccine "enhancer".

Antitumor activity of tributyrin in murine melanoma model

Butyric acid has been known to inhibit growth and to induce differentiation of a variety of tumor cells. Butyrate-treated tumor cells have also been observed to undergo apoptosis. Although butyrate compounds have demonstrated antitumor activity in murine tumor models and have already been admitted to clinical trials in tumor patients, the exact mechanism of their antitumor effects has not been elucidated. The results of our study showed antitumor activity of tributyrin, a butyric acid prodrug, in murine melanoma model and are strongly suggestive that antiangiogenic effects could participate in antitumor effects of butyrate compounds in vivo.

Synthesis of tetrapeptide p-nitrophenylanilides containing dehydroalanine and dehydrophenylalanine and their influence on cathepsin C activity

Three dehydrotetrapeptides of rationally varying structure were prepared and tested as affectors of cathepsin C. These compounds appeared to be substrates of the enzyme, being equipotent with their classical counterparts. Thus, replacement of amino acid in a short peptide by corresponding dehydroamino acid does not prevent cathepsin C in recognizing dehydropeptide as its substrate.

[Advanced abdominal angina due to atherosclerosis with atypical celiac arteries]

It is generally accepted that the abdominal angina develops only when at least two of the three splanchnic vessels-mesenteric arteries and the celiac trunk exhibit a critical obstruction. That common opinion does not, however, take into account anatomical variants of arteries supplying the blood to the intestines. We present a case of a wasted, 40 year old male with a wide spread arteriosclerosis and postprandial pain. The ultrasound examination revealed total occlusion of the superior mesenteric artery (SMA). Celiac trunk (CT) and inferior mesenteric artery (IMA) were patent. The ultrasound indicated that only one splanchic vessel was obstructed; the systemic disorder, the neoplasm, as well as the malabsorption were ruled out. An arteriography of the abdominal aorta and of splanchnic arteries confirmed patency of CT and IMA, also lack of flow in the SMA. Atypical origin of the middle colic artery originating from the bed of CT was also shown. Lack of collaterals between IMA and SMA, typically conducting a sufficient blood flow, resulted in a fully symptomatic abdominal angina. Symptoms were relieved following surgical revascularization.

[Nephropathy in the course of inflammatory connective tissue diseases]

The aim of the study was to assess the frequency of renal complications and also evaluation of renal efficiency with regard to sex and age in children with inflammatory connective tissue diseases. The examination embraced 18 children out of 5657 hospitalised in 19991-1998 in Military University School of Medicine-Dpt of Pediatrics suffering from inflammatory connective tissue diseases, which constitutes 0.32%. They found the following number of isolated cases: 9 cases of juvenile chronic arthritis (JCA), 6 cases of rheumatic fever (RF), and 3 cases of systemic lupus erythematosus (SLE). There were 9 girls and 9 boys. The most frequent symptom of kidneys affection was erythrocyturia. Due to chronic course, reccurrence and the possibility of further complications, children with inflammatory connective tissue diseases, after discharging from hospital, should stay under the care of rheumatological outpatient clinic.

[Nephropathy in the course of Schönlein-Henoch purpura]

The aim of the study was to assess the frequency of renal complications and also evaluation of renal efficiency with regard to sex and age in children with Schonlein-Henoch purpura. 31 children with Schonlein-Henoch disease out of 5004 hospitalised in 6 years time (1994-1999) in Mil. Medical University-Dpt of Pediatrics, underwent the examination, which is 0.62% of all patients. The group of analysed cases consisted of 19 girls (61.3%) and 12 boys (38.7%). 15 of them had changes in kidneys, which constitutes 48.4%. The average age of examined children was 9.1 years. In the most cases upper respiratory tract infections preceded symptoms of the Schonlein-Henoch purpura. The most often complications found in the course of the Schonlein-Henoch purpura were renal ones. The most numerous renal complications affected children between 7 and 9 years of age. Because of chronic and insidious course of the disease, children, after discharging from hospital should stay under specialistic medical care.

[Cyclic vomiting with ketosis as a cause of acute kidney dysfunction: own clinical experience]

The aim of the study was to evaluate renal activity during cyclic vomiting with ketosis. The clinical material was obtained from 50 cases of children hospitalized in Department of Pediatrics Military Medical University within 1993-1999 what makes about 1% of all patients. The examined group consisted of 26 boys (52%) and 24 girls (48%). Three of the children were repeatedly hospitalized (3 to 8 times) because of acetonemic vomiting. The special attention during the laboratory studies was paid to evaluation of renal activity. Vomiting with ketosis were associated with temporary kidneys acute dysfunction in 46% of cases. In 98% of cases the parenteral hydration was necessary. Ketonemic vomiting with kidneys dysfunction was observed mainly with the children in pre-school age.

Thymidylate synthases from Hymenolepis diminuta and regenerating rat liver: purification, properties, and inhibition by substrate and cofactor analogues

Comparative studies of thymidylate synthases, isolated from the tapeworm, Hymenolepis diminuta, and regenerating liver of its host, rat, aimed at a possibility of specific inhibition of the helminthic enzyme, are presented. While similar in structure (dimers with monomer molecular masses of 33.7 kDa and 34.9 kDa, respectively) and parameters describing interactions with substrates and products, the tapeworm and rat enzymes differed in the dependences of reaction velocity on temperature (Arrhenius plots biphasic and linear, respectively). The tapeworm, compared with the host, enzyme was less sensitive to the competitive slow-binding inhibition by 5-fluoro-dUMP and its 2-thio congener, but equally sensitive to inhibition by 4-thio-5-fluoro-dUMP, N4-hydroxy-dCMP and N4-hydroxy-5-fluoro-dCMP, the latter being more potent inhibitor of the parasite enzyme than 5-fluoro-dUMP. alpha-Anomer of 5-fluoro-dUMP behaved as a very weak competitive slow-binding inhibitor of both enzymes. Both enzymes differed markedly in sensitivity to inhibition by 10-propargyl-5,8-dideazafolate and its di- and triglutamates (pddPteGlu1-3), with pddPteGlu1 being stronger inhibitor of the mammalian enzyme, but pddPteGlu3 showing opposite specificity. Sulfonamidobenzoylglutamate analogue of pddPteGlu (pddPteSO2Glu) and 2-desamino-2-methyl derivative of this analogue (CH3pddPteSO2Glu) were weaker inhibitors of both enzymes than the parent compound. Substitution of the glutamyl residue in CH3pddPteSO2Glu with either norvaline or alanine increased inhibition potency, whereas similar substitutions with glycine, valine or phenylglycine were without a distinct effect with the host enzyme but weakened inhibition of the tapeworm enzyme.

Null cell identification and characterization with OKT16: an anti-p40 monoclonal antibody

A murine monoclonal antibody, OKT16, specific for human lymphocytes of T lineage, was isolated by standard immunization and hybridization techniques. The distribution of the antigen defined by OKT16 was similar to the antigen reactive with monoclonal antibodies 3A1 and WT1. This identity of antigen targets was confirmed in an enzyme-linked immunosorbent assay system and by sequential immunoprecipitation. Under reducing conditions, OKT16 reacted with an antigen of 40K daltons; however, under nonreducing conditions this antigen appeared as an 84K-dalton molecule, which suggests that the p40 antigen exists as a disulfide-linked dimer. By indirect immunofluorescence, OKT16 reacted with a greater fraction of nonrosetting, non-B (null) lymphocytes than with antibodies to other T cell-specific proteins. Two-color immunofluorescence demonstrated the coexpression of the T16 antigen and the C3bi receptor on most null cells. The T10 antigen (found on cortical thymocytes and activated peripheral T cells) was restricted to most T16-bearing null cells and expression of the Fc receptor for aggregated IgG (defined by monoclonal antibody 73.1) was restricted to a major subset of T16-bearing null cells. The T cell-specific markers defined by OKT8, OKT11, and OKT17, as well as the monocyte marker defined by OKM5, were expressed by smaller subsets of OKT16-reactive null cells. These studies support by phenotypic analysis the functional heterogeneity ascribed to null cells. The 40K-dalton T16 antigen has the most extensive null cell representation of all the T lineage markers described to date.

Distinct classes of human T-cell activation antigens

The characterization of three groups of antigens expressed by activated human T lymphocytes and detected by monoclonal antibodies is reported. Antigens defined by OKT19, OKT21, and OKT22 do not appear on in vitro activated T cells until increases in DNA synthesis become apparent and are not detected on most Interleukin 2 (IL-2)-independent cell lines and normal peripheral blood lymphocytes, monocytes, and granulocytes. Cell surface molecules reactive with the monoclonal antibodies OKT23 and OKT24 are displayed prior to any notable increase in DNA synthesis and are present on IL-2 independent cell lines, irrespective of lineage. T23 and T24 do not appear on peripheral blood cells and their distribution more closely resembles that of the T9 antigen (the receptor for transferrin) than antigens of the other groups. The third group of antigens, T14 and T20, have been classified as "early" antigens relative to DNA synthesis. They are expressed by distinct populations of normal lymphoid cells as well as by some IL-2-independent cell lines. Display of each group of activation antigens on T lymphocytes can be induced by either phytohemagglutinin, purified protein derivative from tuberculin, or allogeneic non-T cells, is not restricted to the OKT4+ or OKT8+ subsets, and is predominant on cells exhibiting the light-scattering properties of blast cells. The relative lack of expression of these antigens among normal peripheral blood cells make them attractive candidates for identifying changes in the status of immune activation.