A collaborative biomedical image mining framework: application on the image analysis of microscopic kidney biopsies

The analysis and characterization of biomedical image data is a complex procedure involving several processing phases, like data acquisition, preprocessing, segmentation, feature extraction and classification. The proper combination and parameterization of the utilized methods are heavily relying on the given image data set and experiment type. They may thus necessitate advanced image processing and classification knowledge and skills from the side of the biomedical expert. In this work, an application, exploiting web services and applying ontological modeling, is presented, to enable the intelligent creation of image mining workflows. The described tool can be directly integrated to the RapidMiner, Taverna or similar workflow management platforms. A case study dealing with the creation of a sample workflow for the analysis of kidney biopsy microscopy images is presented to demonstrate the functionality of the proposed framework.

Unifying the integration, analysis and interpretation of multi-omic datasets: exploration of the disease networks of Obstructive Nephropathy in children

The wealth of data amassed by the utilization of various high-throughput techniques, in various layers of molecular dissection, stresses the critical role of the unification of the computational methodologies applied in biological data handling, storage, analysis and visualization. In this article, a generic workflow is showcased in a multi-omic dataset that is used to study Obstructive Nephropathy (ON) in children, integrating microarray data from several biological layers (transcriptomic, post-transcriptomic, proteomic). The workflow exploits raw measurements and through several analytical stages (preprocessing, statistical and functional), which entail various parsing steps, reaches the visualization stage of the heterogeneous, broader, molecular interacting network derived. This network, where the interconnected entities are exploiting the knowledge stored in public repositories, represents a systems level interpretation of the pathological state probed.

Abstract 4125: Suppression of the mevalonate pathway and oncogenic signaling may underlie the tumor-suppressing effects of KLK5 in breast cancer

Kallikrein-related peptidase 5 (KLK5) has been implicated in different types of cancer based on its aberrant expression in tumor cell lines and tissue specimens and in vitro data, however, functional association is missing. Here, we confirmed that KLK5 is very frequently down-regulated or inactivated in breast cancers of different subtypes. Reconstitution of KLK5 expression by stable transfection in KLK5-negative MDA-MB-231 cells remarkably reversed their malignant phenotype both in vitro (wound scratch and soft agar assay) and in vivo (orthotopic xenograft growth in SCID mice). We found that in KLK5 transfectants Snail1 and the mesenchymal marker vimentin were highly downregulated, pointing to a potential involvement of KLK5 in mesenchymal-to-epithelial transdifferentiation, however, re-expression of E-cadherin could not be demonstrated. Importantly, it appears that KLK5 may severely affect the overall output of the proteolytic web as it minimized the proteolytic activities of MMP9 and MMP3. Unexpectedly, transcriptomic profiling revealed that reconstitution of KLK5 expression suppresses the mevalonate pathway of cholesterol biosynthesis by highly up-regulating INSIG1 (insulin induced gene 1), a major negative regulator of HMGCR (3-hydroxy-3-methylgluratyl-CoA reductase), while KLK5 may also affect cholesterol uptake, as the LDLR (LDL receptor) and PCSK9 (proprotein convertase subtilisin-like/kexin type 9), the main regulator of LDLR, were both found significantly upregulated in KLK5 transfectants. A functional role of KLK5 in the regulation of the mevalonate pathway and protein-prenylation circuitries was demonstrated by reduced cellular cholesterol and prenylation levels, end products of this pathway. Reduced prenylation was shown by the remarkable reduction in the levels of activated RhoA, which must be subjected to isoprenylation (mainly geranyl-geranylation) for activation. To our knowledge, this is the first demonstration of a protease involved in the crosstalk between metabolic pathways and oncogenic signaling. Moreover, among the genes found up or down-regulated upon KLK5 re-expression (i.e. the “KLK5 signature”) were several genes known to be involved in atherosclerosis and other lipid-related metabolic disorders. Overall, KLK5 may represent a nodal interconnection of proteolytic and signaling pathways in cancer but may also participate in pathways associated with metabolic diseases, in support of the emerging concept of common genetic networks governing both cancer and lipid-associated disorders.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4125. doi:1538-7445.AM2012-4125

Intra-arterial prostaglandin e(1) infusion in patients with rest pain: short-term results

Purpose. To present our results after short-term (1 month) intra-arterial infusion therapy of PGE₁-alprostadil via a port system implanted in the ipsilateral external iliac artery (EIA) in patients with severe rest pain. Methods. Ten patients with severe rest pain were included. All patients showed extensive peripheral vascular disease below the knee. The tip of the catheter was introduced via a retrograde puncture in the ipsilateral external iliac artery (EIA). The patients received intraarterial infusion of PGE₁, 20 mgr alprostadil daily, via the port catheter for 1 month. Results. Clinical success was evaluated according to subjective grading of pain (group A significant decrease, group B moderate decrease and group C no response). A significant decrease of rest pain was observed in 8 (group A, 80%) patients, a moderate decrease in 2 (Group B, 20%), whereas no patients demonstrated any significant response. Both patients of group B had Buergers' disease and continue to smoke during therapy. No peripheral thrombosis or clinical deterioration was noticed. Conclusion. Intraarterial infusion of PGE₁ alprostadil on a daily basis, using a port catheter into the ipsilateral EIA, in selected patients with severe rest pain, seems to be very effective, without any serious complications.

GOrevenge: a novel generic reverse engineering method for the identification of critical molecular players, through the use of ontologies

The ever-increasing use of ontologies in modern biological analysis and interpretation facilitates the understanding of the cellular procedures, their hierarchical organization, and their potential interactions at a system's level. Currently, the gene ontology serves as a paradigm, where through the annotation of whole genomes of certain organisms, genes subsets selected, either from high-throughput experiments or with an established pivotal role regarding the probed disease, can act as a starting point for the exploration of their underlying functional interconnections. This may also aid the elucidation of hidden regulatory mechanisms among genes. Reverse engineering the functional relevance of genes to specific cellular pathways and vice versa, through the exploitation of the inner structure of the ontological vocabularies, may help impart insight regarding the identification and prioritization of the critical role of specific genes. The proposed graph-theoretical method is showcased in a pancreatic cancer and a T-cell acute lymphoblastic leukemia gene set, incorporating edge and Resnik semantic similarity metrics, and systematically evaluated regarding its performance.

Coactivation of GR and NFKB alters the repertoire of their binding sites and target genes

Glucocorticoid receptor (GR) exerts anti-inflammatory action in part by antagonizing proinflammatory transcription factors such as the nuclear factor kappa-b (NFKB). Here, we assess the crosstalk of activated GR and RELA (p65, major NFKB component) by global identification of their binding sites and target genes. We show that coactivation of GR and p65 alters the repertoire of regulated genes and results in their association with novel sites in a mutually dependent manner. These novel sites predominantly cluster with p65 target genes that are antagonized by activated GR and vice versa. Our data show that coactivation of GR and NFKB alters signaling pathways that are regulated by each factor separately and provide insight into the networks underlying the GR and NFKB crosstalk.

Transcatheter arterial embolization as therapy of renal angiomyolipomas: the evolution in 15 years of experience

OBJECTIVE

This study aims at presenting the evolution of the embolization technique in treating renal angiomyolipomas (AMLs) either diagnosed in patients with acute bleeding or discovered accidentally.

METHODS

Ten patients with renal AMLs have been through thirteen selective transcatheter arterial embolizations for 15 years. Two patients had tuberous sclerosis complex (TSC) with bilateral tumors and were embolized twice. Four embolic materials were employed: PVA particles, Gianturco coils, microspheres and microcoils. Catheterization was achieved by means of 5F Cobra 2 catheters and coaxial microcatheter systems.

RESULTS

On an emergency basis, embolization was a first-line treatment. In one case, surgery was necessary; in two patients, a second embolization was performed. When treatment was preventive, a single embolization proved to be sufficient, as well. There was no significant deterioration of the serum creatinine levels in the post-embolization period.

CONCLUSION

Selective arterial embolization is a rather safe and effective technique to treat AMLs both urgently and preventively. Different embolic materials can be employed. Microspheres and microcatheters stand for new promising materials.

Delineation and interpretation of gene networks towards their effect in cellular physiology- a reverse engineering approach for the identification of critical molecular players, through the use of ontologies

Exploiting ontologies, provides clues regarding the involvement of certain molecular processes in the cellular phenotypic manifestation. However, identifying individual molecular actors (genes, proteins, etc.) for targeted biological validation in a generic, prioritized, fashion, based in objective measures of their effects in the cellular physiology, remains a challenge. In this work, a new meta-analysis algorithm is proposed for the holistic interpretation of the information captured in -omic experiments, that is showcased in a transcriptomic, dynamic, DNA microarray dataset, which examines the effect of mastic oil treatment in Lewis lung carcinoma cells. Through the use of the Gene Ontology this algorithm relates genes to specific cellular pathways and vice versa in order to further reverse engineer the critical role of specific genes, starting from the results of various statistical enrichment analyses. The algorithm is able to discriminate candidate hub-genes, implying critical biochemical cross-talk. Moreover, performance measures of the algorithm are derived, when evaluated with respect to the differential expression gene list of the dataset.

An in silico compartmentalized metabolic model of Brassica napus enables the systemic study of regulatory aspects of plant central metabolism

Biochemical network reconstructions represent valuable tools for the computational metabolic modeling of organisms that present a great biotechnological interest. An in silico multi-compartmental model of the central metabolism of the plant Brassica napus (Rapeseed) was constructed, aiming to investigate the metabolic properties of the Brassicaceae family. This family comprises many plants with major importance for the energy and nutrition sector, including the model plant Arabidopsis thaliana. The model utilized as objective function to be subsequently optimized, the biomass production of rapeseed developing embryos, which are characterized by a very high, oil content, up to 60% of biomass weight. In order to study global network properties of seed metabolism, various methods were employed, like Flux Balance Analysis, Principal Component Analysis of the flux space and reaction deletion studies, which simulate the effect of gene knock-out experiments. The model successfully simulated seed growth during the stage of oil accumulation and provided insight, regarding certain aspects of network plasticity, with the emphasis given in lipid biosynthesis regulation.

Enabling distributed processing and management of biological data using the grid and web technologies

Transcriptomic technologies have dramatically reshaped modern biological research by deriving profiles of genome-wide expression of living organisms, and producing an unprecedented wealth of quantitative data. Given this characteristic, microarray experiments are considered high-throughput both in terms of data (data intensive) and processing (computationally intensive). GRISSOM Web Tools enable the exploitation of GRID resources for DNA microarray data distributed processing and management. It provides experts with a complete web-based solution for managing, searching and disseminating biological knowledge in the context of gene expression patterns on a genomic scale. Through the incorporation of novel workflows and various web services, the platform is gradually transformed to a powerful environment for knowledge discovery in the biomedical research.

A transcriptomic computational analysis of mastic oil-treated Lewis lung carcinomas reveals molecular mechanisms targeting tumor cell growth and survival

Background

Mastic oil from Pistacia lentiscus variation chia, a blend of bioactive terpenes with recognized medicinal properties, has been recently shown to exert anti-tumor growth activity through inhibition of cancer cell proliferation, survival, angiogenesis and inflammatory response. However, no studies have addressed its mechanisms of action at genome-wide gene expression level.

Methods

To investigate molecular mechanisms triggered by mastic oil, Lewis Lung Carcinoma cells were treated with mastic oil or DMSO and RNA was collected at five distinct time points (3-48 h). Microarray expression profiling was performed using Illumina mouse-6 v1 beadchips, followed by computational analysis. For a number of selected genes, RT-PCR validation was performed in LLC cells as well as in three human cancer cell lines of different origin (A549, HCT116, K562). PTEN specific inhibition by a bisperovanadium compound was applied to validate its contribution to mastic oil-mediated anti-tumor growth effects.

Results

In this work we demonstrated that exposure of Lewis lung carcinomas to mastic oil caused a time-dependent alteration in the expression of 925 genes. GO analysis associated expression profiles with several biological processes and functions. Among them, modifications on cell cycle/proliferation, survival and NF-κB cascade in conjunction with concomitant regulation of genes encoding for PTEN, E2F7, HMOX1 (up-regulation) and NOD1 (down-regulation) indicated some important mechanistic links underlying the anti-proliferative, pro-apoptotic and anti-inflammatory effects of mastic oil. The expression profiles of Hmox1, Pten and E2f7 genes were similarly altered by mastic oil in the majority of test cancer cell lines. Inhibition of PTEN partially reversed mastic oil effects on tumor cell growth, indicating a multi-target mechanism of action. Finally, k-means clustering, organized the significant gene list in eight clusters demonstrating a similar expression profile. Promoter analysis in a representative cluster revealed shared putative cis-elements suggesting a common regulatory transcription mechanism.

Conclusions

Present results provide novel evidence on the molecular basis of tumor growth inhibition mediated by mastic oil and set a rational basis for application of genomics and bioinformatic methodologies in the screening of natural compounds with potential cancer chemopreventive activities.

Gene ARMADA: an integrated multi-analysis platform for microarray data implemented in MATLAB

Background

The microarray data analysis realm is ever growing through the development of various tools, open source and commercial. However there is absence of predefined rational algorithmic analysis workflows or batch standardized processing to incorporate all steps, from raw data import up to the derivation of significantly differentially expressed gene lists. This absence obfuscates the analytical procedure and obstructs the massive comparative processing of genomic microarray datasets. Moreover, the solutions provided, heavily depend on the programming skills of the user, whereas in the case of GUI embedded solutions, they do not provide direct support of various raw image analysis formats or a versatile and simultaneously flexible combination of signal processing methods.

Results

We describe here Gene ARMADA (Automated Robust MicroArray Data Analysis), a MATLAB implemented platform with a Graphical User Interface. This suite integrates all steps of microarray data analysis including automated data import, noise correction and filtering, normalization, statistical selection of differentially expressed genes, clustering, classification and annotation. In its current version, Gene ARMADA fully supports 2 coloured cDNA and Affymetrix oligonucleotide arrays, plus custom arrays for which experimental details are given in tabular form (Excel spreadsheet, comma separated values, tab-delimited text formats). It also supports the analysis of already processed results through its versatile import editor. Besides being fully automated, Gene ARMADA incorporates numerous functionalities of the Statistics and Bioinformatics Toolboxes of MATLAB. In addition, it provides numerous visualization and exploration tools plus customizable export data formats for seamless integration by other analysis tools or MATLAB, for further processing. Gene ARMADA requires MATLAB 7.4 (R2007a) or higher and is also distributed as a stand-alone application with MATLAB Component Runtime.

Conclusion

Gene ARMADA provides a highly adaptable, integrative, yet flexible tool which can be used for automated quality control, analysis, annotation and visualization of microarray data, constituting a starting point for further data interpretation and integration with numerous other tools.

KEGGconverter: a tool for the in-silico modelling of metabolic networks of the KEGG Pathways database

BACKGROUND

The KEGG Pathway database is a valuable collection of metabolic pathway maps. Nevertheless, the production of simulation capable metabolic networks from KEGG Pathway data is a challenging complicated work, regardless the already developed tools for this scope. Originally used for illustration purposes, KEGG Pathways through KGML (KEGG Markup Language) files, can provide complete reaction sets and introduce species versioning, which offers advantages for the scope of cellular metabolism simulation modelling. In this project, KEGGconverter is described, implemented also as a web-based application, which uses as source KGML files, in order to construct integrated pathway SBML models fully functional for simulation purposes.

RESULTS

A case study of the integration of six human metabolic pathways from KEGG depicts the ability of KEGGconverter to automatically produce merged and converted to SBML fully functional pathway models, enhanced with default kinetics. The suitability of the developed tool is demonstrated through a comparison with other state-of-the art relevant software tools for the same data fusion and conversion tasks, thus illustrating the problems and the relevant workflows. Moreover, KEGGconverter permits the inclusion of additional reactions in the resulting model which represent flux cross-talk with neighbouring pathways, providing in this way improved simulative accuracy. These additional reactions are introduced by exploiting relevant semantic information for the elements of the KEGG Pathways database. The architecture and functionalities of the web-based application are presented.

CONCLUSION

KEGGconverter is capable of producing integrated analogues of metabolic pathways appropriate for simulation tasks, by inputting only KGML files. The web application acts as a user friendly shell which transparently enables the automated biochemically correct pathway merging, conversion to SBML format, proper renaming of the species, and insertion of default kinetic properties for the pertaining reactions. The tool is available at: http://www.grissom.gr/keggconverter.

OPTICAL PROPERTY CHARACTERIZATION BASED ON A PHASE FUNCTION APPROXIMATION MODEL

Recently, we generalized the Delta-Eddington phase function and applied it to the radiative transfer equation for modeling the photon propagation in biological tissue. The resultant phase approximation model was shown to be highly accurate with a wide range of optical properties, including the strongly absorbing and weakly scattering media. In this paper, we propose phase-approximation-based method for estimating the optical parameters. Specifically, we design an iterative algorithm to take advantage of both the global search ability of the differential evolution algorithm and the efficiency of the conjugate gradient method. Then, we demonstrate the feasibility and merits of the proposed method in both numerical simulation and phantom experiments.

Comparative expression profiling in pulmonary fibrosis suggests a role of hypoxia-inducible factor-1alpha in disease pathogenesis

RATIONALE

Despite intense research efforts, the etiology and pathogenesis of idiopathic pulmonary fibrosis remain poorly understood.

OBJECTIVES

To discover novel genes and/or cellular pathways involved in the pathogenesis of the disease.

METHODS

We performed expression profiling of disease progression in a well-characterized animal model of the disease. Differentially expressed genes that were identified were compared with all publicly available expression profiles both from human patients and animal models. The role of hypoxia-inducible factor (HIF)-1alpha in disease pathogenesis was examined with a series of immunostainings, both in the animal model as well as in tissue microarrays containing tissue samples of human patients, followed by computerized image analysis.

MEASUREMENTS AND MAIN RESULTS

Comparative expression profiling produced a prioritized gene list of high statistical significance, which consisted of the most likely disease modifiers identified so far in pulmonary fibrosis. Extending beyond target identification, a series of meta-analyses produced a number of biological hypotheses on disease pathogenesis. Among them, the role of HIF-1 signaling was further explored to reveal HIF-1alpha overexpression in the hyperplastic epithelium of fibrotic lungs, colocalized with its target genes p53 and Vegf.

CONCLUSIONS

Comparative expression profiling was shown to be a highly efficient method in identifying deregulated genes and pathways. Moreover, tissue microarrays and computerized image analysis allowed for the high-throughput and unbiased assessment of histopathologic sections, adding substantial confidence in pathologic evaluations. More importantly, our results suggest an early primary role of HIF-1 in alveolar epithelial cell homeostasis and disease pathogenesis, provide insights on the pathophysiologic differences of different interstitial pneumonias, and indicate the importance of assessing the efficacy of pharmacologic inhibitors of HIF-1 activity in the treatment of pulmonary fibrosis.

Microarray analysis of survival pathways in human PC-3 prostate cancer cells

BACKGROUND

Insulin-like growth factor 1 (IGF-1), transforming growth factor beta 1 (TGFbeta1), and interleukin 6 (IL-6), act as survival factors inhibiting chemotherapy-induced apoptosis in PC-3 human prostate cancer cells, in vitro.

MATERIALS AND METHODS

To study the intracellular pathways activated by these survival factors we performed a comparative genomic analysis using oligonucleotide microarray chips. A validation by real time-PCR was also performed for the genes of interest.

RESULTS

The expression data derived were analysed using various normalization algorithms. The differentially expressed genes were clustered and their ontological annotations were statistically tested to provide evidence for possible deregulated biological processes on the action of the aforementioned survival factors. Emphasis was given on the regulation and the role of the genes AKR1C1, SDPR and GADD45B in the survival pathways of prostate cancer cells, whose expression was also validated by real time-PCR.

CONCLUSION

The overall analyses reveal an overrepresentation of differentially expressed genes related to cellular processes such as cell cycle regulation, lipid metabolism and steroid biosynthesis.

Acute Iliac Artery Rupture: Endovascular Treatment

The authors present 7 patients who suffered iliac artery rupture over a 2 year period. In 5 patients, the rupture was iatrogenic: 4 cases were secondary to balloon angioplasty for iliac artery stenosis and 1 occurred during coronary angioplasty. In the last 2 patients, the rupture was secondary to iliac artery mycotic aneurysm. Direct placement of a stent-graft was performed in all cases, which was dilated until extravasation was controlled. Placement of the stent-graft was successful in all the cases, without any complications. The techniques used, results, and mid-term follow-up are presented. In conclusion, endovascular placement of a stent-graft is a quick, minimally invasive, efficient, and safe method for emergency treatment of acute iliac artery rupture, with satisfactory short- and mid-term results.

Effect of green tea on angiogenesis and severity of atherosclerosis in cholesterol-fed rabbit

BACKGROUND AND AIMS

Since the development of the atherosclerotic plaque requires the growth of new microvessels in the plaque itself (vasa vasorum), we postulated that green tea may exert an anti-atherogenic effect.

METHODS AND RESULTS

Thirteen male New Zealand white rabbits were studied for 17 weeks. All rabbits were fed an hypecholesterolemic diet. After 2 weeks of adaptation rabbits were randomly assigned into two groups. Animals in Group A were fed the hypercholesterolemic diet and received plain tap water ad libitum. Animals in Group B were fed with the same diet and furthermore received 2.5% (g/g) green tea for 17 weeks.

CONCLUSION

According to our results the atherosclerotic lesions were more severe in Group B than in Group A specimens. Also, the number of VEGF positively stained foam cells and smooth muscle cells of Group B were significantly greater than in Group A. About 30% less plaque was found in Group A than in the control group (Group B). So, our study showed that the consumption of green tea leads to a reduction of atherosclerosis as well as a significant decrease of VEGF expression in the atherosclerotic plaque of rabbit aorta. The hypothesis that probably green tea may produce its anti-atherogenetic effect through an anti-angiogenetic mechanism needs more investigation.

Readout of the Optical PET (OPET) Detector

The design of an imaging system capable of detecting both high-energy γ-rays and optical wavelength photons is underway at the Crump Institute for Molecular Imaging. This system will noninvasively image small animal models in vivo for the presence of positron emission tomographic (PET) and optical signals. The detector will consist of modules of multichannel photomultiplier tubes (MC-PMT) coupled to arrays of scintillator crystals. The MC-PMT will detect both the photons produced due to bioluminescence and the photons generated by the interaction of γ-rays within the crystals. The long wavelength photons produced through bioluminescence are only slightly attenuated by these crystals and are detected directly at the photocathode of the MC-PMT, resulting in signals of small (5-10 mV) short (~15 ns) pulses. In contrast, annihilation (511 keV) γ-rays interacting in the scintillator crystal send large bursts of photons to the PMT, and result in pulses that can be as large as 500 mV and > 200 ns duration. The processing of pulses with such different characteristics in a single circuit requires significant alteration of the standard pulse processing circuitry used in PET scanners. In this paper, we discuss the requirements of such a circuit and show the results of implementation of one design using single and multiple channel PMTs.

Endovascular Treatment of Renal Arteriovenous Malformations

We report a case of renal arteriovenous malformation treated with superselective endovascular embolization using a light mixture of n-butyl-2-cyanoacrylate and Lipiodol. Diagnostic imaging modalities and treatment methods are discussed. In conclusion, successful superselective embolization should be the standard of care.

Effects of Superselective Embolization for Renal Vascular Injuries on Renal Parenchyma and Function

AIM

Our objective was to evaluate the outcome of superselective embolization used for treatment of renal vascular injuries on renal parenchyma and renal function.

MATERIALS AND METHODS

Between January 1999 and December 2001, 6 consecutive patients (five males, one female, mean age 45 years) underwent embolization to treat bleeding from renal vascular injuries, resulting from iatrogenic interventions (4) and blunt abdominal trauma (2). Five patients had increased serum creatinine. Angiography depicted a pseudoaneurysm (PA) in three, PA with arteriovenous fistula (AVF) in one, and active extravasation in two patients. Superselective catheterization was achieved using a 5-F catheter in three, and coaxial microcatheter in the remaining three cases. All lesions were successfully embolized with 0.035" or 0.018" coils.

RESULTS

Bleeding was ceased in all patients and did not recur. Mean post-embolization parenchymal ischemic area was 11.7% (range: 0-30%). Imaging follow-up (mean: 12 months, range: 5-23) showed that mean parenchymal infarcted area was 6% (range: 0-15%). Serum creatinine level was normal in all patients one week after the procedure and at the latest follow-up.

CONCLUSION

Superselective embolization resulted in permanent cessation of bleeding. Serious parenchymal infarction was prevented and serum creatinine level returned to the pre-bleeding values. Embolization should be considered as the treatment of choice in this patient population.

Detector Concept for OPET-A Combined PET and Optical Imaging System

The design of an imaging system capable of detecting both high-energy γ-rays and optical wavelength photons is underway at the UCLA Crump Institute for Molecular Imaging. This system, which we call optical PET (OPET), will be capable of non-invasively and repeatedly imaging small animal models in vivo for the presence of PET and optical signals. In this study, we describe the physical principles behind the operation of the OPET imaging system and discuss the design concept for one of the detector modules. Additionally, we demonstrate the operation of an initial prototype detector module for simultaneous detection and imaging of annihilation radiation and single optical photons emanating from separate sources. These results indicate that the construction of an imaging system based on this detector technology is feasible.

Complications of Lower-Extremity Outpatient Arteriography via Low Brachial Artery

We retrospectively evaluated low brachial artery puncture for arteriography and its complications as an alternative approach route for bilateral lower extremity run-off. Using the Seldinger technique and catheterization with a sheathless 4-F multiple side-hole pigtail catheter, we performed 2250 low brachial artery punctures in outpatients. The right brachial artery (RBA) was successfully punctured in 2039 patients; the left brachial artery (LBA) in 200. The transfemoral approach was used in 11 patients when catheterizing either of brachial arteries failed. Ten major or moderate complications (2 pseudoaneurysms, 2 thrombosis, 1 dissection and 5 hematomas) were encountered. Surgical intervention was necessary in three cases. There were no transient ischemic attacks. Twenty-one patients suffered temporary loss of radial pulse which returned spontaneously in less than 1 hour. One patient demonstrated prolonged loss of pulse which required heparin. Low brachial artery puncture and catheterization at the antecubital fossa is a very safe and cost-effective alternative to the femoral artery approach for lower extremity intra-arterial arteriography in the hands of experienced operators. The success rate in catheterizing one of the brachial arteries was 99.52% with a low significant complications rate of 0.44%. The transbrachial approach should be used as a standard method for lower extremity IA-DSA in an outpatient setting.

Stent therapy for malignant superior vena cava syndrome: should be first line therapy or simple adjunct to radiotherapy

The goal of this paper is to present our experience with superior vena cava (SVC) stenting, as first line procedure for immediate relief, in patients with malignancy, and its potential influence in the subsequent radiotherapy (XRT). Over a 1-year period, 18 patients with SVC syndrome due to severe stenosis secondary to mediastinal malignancy were referred for stent insertion. A SVC score was used to measure treatment effectiveness. Stent insertion had been successful in 18/18 patients (technical success 100%). All patients experienced symptomatic relief within few hours of the procedure. There were no major complications. In all patients we were able to start radiotherapy (XRT) the next day, after stenting according to our new institutional protocol. All patients were able to comply with the XRT program, perfectly well.

CONCLUSIONS

SVC stenting provides immediate significant relief of the very annoying SVC syndrome symptoms, thus facilitating excellent compliance of all the patients to the subsequently XRT protocols. We strongly recommend SVC stenting as first line procedure, in patients with SVC syndrome due to malignancy prior to radiotherapy.

Assessing food additive toxicity using a cell model

Food additives are widely used for technological purposes and their presence is often substantial daily diet. They have also been accused forvarious toxic reactions in humans. The toxicity of the food color tartrazine, the preservatives sodium nitrate and sodium benzoate, and the antioxidant BHT, was studied using the protozoan Tetrahymenapyriformis as a toxicological model. The 4 food additives were added to Tetrahymena cultures and DNA content of the protozoan nuclei measured by an image analysis system. These food additives caused a statistically significant increase in DNA content suggesting stimulation of the mitotic process. This system may contribute to the investigation of the cellular action of food additives, since mitogenic stimuli substantially alter susceptibility to chemical carcinogenesis.

Model-based normalization for iterative 3D PET image reconstruction

We describe a method for normalization in 3D PET for use with maximum a posteriori (MAP) or other iterative model-based image reconstruction methods. This approach is an extension of previous factored normalization methods in which we include separate factors for detector sensitivity, geometric response, block effects and deadtime. Since our MAP reconstruction approach already models some of the geometric factors in the forward projection, the normalization factors must be modified to account only for effects not already included in the model. We describe a maximum likelihood approach to joint estimation of the count-rate independent normalization factors, which we apply to data from a uniform cylindrical source. We then compute block-wise and block-profile deadtime correction factors using singles and coincidence data, respectively, from a multiframe cylindrical source. We have applied this method for reconstruction of data from the Concorde microPET P4 scanner. Quantitative evaluation of this method using well-counter measurements of activity in a multicompartment phantom compares favourably with normalization based directly on cylindrical source measurements.

Abdominal aortic aneurysm and renal artery stenosis: renal function and blood pressure before and after endovascular treatment

We describe three patients with abdominal aortic aneurysm (AAA) and renal artery stenosis (RAS). These patients were treated by placement of an aortic endograft and angioplasty or stenting of the renal artery. After the procedure renal function improved or remained stable in two patients and deteriorated slightly in one. Blood pressure was reduced in one hypertensive patient and remained normal in the other two normotensive patients. In conclusion, simultaneous treatment of AAA and RAS with aortic endograft placement and renal artery angioplasty with or without stent, is a safe and effective technique for selected high-risk patients.

Renal artery stenting for renal insufficiency in solitary kidney in 26 patients

OBJECTIVE

to present our experience with stent placement in renal arteries in solitary kidneys for treating renal insufficiency.

DESIGN

retrospective analysis.

MATERIALS

in 26 patients with solitary kidney (17 men, 9 women, mean age: 63 years), presented with renal insufficiency (se-creat >0.144 mmol/l), stent was placed in a stenosed renal artery. We analysed the clinical outcome, based on the level of creatinine at 3 months following the procedure. Clinical benefit was considered when there was a decrease compared to the baseline creatinine by >20% or a stabilisation of the creatinine value (+/-20% of the baseline).

RESULTS

in 16 of the 26 patients (62%), clinical benefit was achieved. However, 38% of the study population, renal function continued to deteriorate. Baseline creatinine value was the single best predictor for clinical benefit achievement (odds ratio: 13; 95% confidence intervals: 1.6-107, p=0.01).

CONCLUSION

renal stenting results in improvement or stabilisation of renal function in the majority of the patients with solitary kidneys and renal artery stenosis, presenting with renal insufficiency. Because best outcome was observed mainly in those patients with not progressed renal insufficiency, intervention should be focused on that group.

Detector development for microPET II: a 1 microl resolution PET scanner for small animal imaging

We are currently developing a small animal positron emission tomography (PET) scanner with a design goal of 1 microlitre (1 mm3) image resolution. The detectors consist of a 12 x 12 array of 1 x 1 x 10 mm lutetium oxyorthosilicate (LSO) scintillator crystals coupled to a 64-channel photomultiplier tube (PMT) via 5 cm long optical fibre bundles. The optical fibre connection allows a high detector packing fraction despite the dead space surrounding the active region of the PMT. Optical fibre bundles made from different types of glass were tested for light transmission, and also their effects on crystal identification and energy resolution, and compared to direct coupling of the LSO arrays to the PMTs. We also investigated the effects of extramural absorber (EMA) in the fibre bundles. Based on these results, fibre bundles manufactured from F2 glass were selected. We built three pairs of prototype detectors (directly coupled LSO array, fibre bundle without EMA and fibre bundle with EMA) and measured flood histograms, energy resolution, intrinsic spatial resolution and timing resolution. The results demonstrated an intrinsic spatial resolution (FWHM) of 1.12 mm (directly coupled), 1.23 mm (fibre bundle without EMA coupling) and 1.27 mm (fibre bundle with EMA coupling) using an approximately 500 microm diameter Na-22 point source. Using a 330 microm outer diameter steel needle line source filled with F-18, spatial resolution for the detector with the EMA optical fibre bundle improved to 1.05 mm. The respective timing and energy FWHM values were 1.96 ns, 21% (directly coupled), 2.20 ns, 23% (fibre bundle without EMA) and 2.99 ns, 30% (fibre bundle with EMA). The peak-to-valley ratio in the flood histograms was better with EMA (5:1) compared to the optical fibre bundle without EMA (2.5:1), due to the decreased optical cross-talk. In comparison to the detectors used in our current generation microPET scanner, these detectors substantially improve on the spatial resolution, preserve the timing resolution and provide adequate energy resolution for a modern high-resolution animal PET tomograph.

Imaging and localization of pancreatic insulinomas

For pancreatic insulinomas, the treatment of choice is surgical excision, which when successful is curative. Intraoperative palpation combined with ultrasonography theoretically depict almost all tumors, however the accuracy of palpation is improved by the preoperative localization. All recent advances in imaging have improved the likelihood for curative surgical resection. Our purpose is to demonstrate the characteristics of all modalities, which may be used in the preoperative localization algorithm.

Performance evaluation of the microPET P4: a PET system dedicated to animal imaging

The microPET Primate 4-ring system (P4) is an animal PET tomograph with a 7.8 cm axial extent, a 19 cm diameter transaxial field of view (FOV) and a 22 cm animal port. The system is composed of 168 detector modules, each with an 8 x 8 array of 2.2 x 2.2 x 10 mm3 lutetium oxyorthosilicate crystals, arranged as 32 crystal rings 26 cm in diameter. The detector crystals are coupled to a Hamamatsu R5900-C8 PS-PMT via a 10 cm long optical fibre bundle. The detectors have a timing resolution of 3.2 ns, an average energy resolution of 26%, and an average intrinsic spatial resolution of 1.75 mm. The system operates in 3D mode without inter-plane septa, acquiring data in list mode. The reconstructed image spatial resolution ranges from 1.8 mm at the centre to 3 mm at 4 cm radial offset. The tomograph has a peak system sensitivity of 2.25% at the centre of the FOV with a 250-750 keV energy window. The noise equivalent count rate peaks at 100-290 kcps for representative object sizes. Images from two phantoms and three different types of laboratory animal demonstrate the advantage of the P4 system over the original prototype microPET. including its threefold improvement in sensitivity and a large axial FOV sufficient to image an entire mouse in a single bed position.

Embolisation of a traumatic aneurysm of the posterior circumflex humeral artery in a volleyball player

Repetitive minor vascular injuries caused by physical activity in athletes may lead to ischaemia of the upper extremities. In volleyball players in particular, traumatic aneurysm of the posterior circumflex humeral artery has been reported to be a cause of ischaemia of the arm and hand. Such an aneurysm is described here; it was treated successfully with endovascular embolisation.

Embolization of a segmental renal artery pseudoaneurysm after partial nephrectomy in a solitary kidney

Renal pseudoaneurysms are a well-documented complication following trauma or after percutaneous biopsy. When symptomatic, patients present with hematuria and deteriorating renal function. We present the case of a 62-year-old man who, due to development of a pseudoaneurysm, presented with gross hematuria 10 days after partial nephrectomy for a renal cell carcinoma in a single kidney. A segmental artery was embolized with stainless steel coils without significant loss of the limited renal vascularization.

Management of renal angiomyolipoma by selective arterial embolization

4 Patients with renal angiomyolipomas are presented. One of them had tuberous sclerosis with synchronous bilateral tumors. All the patients were symptomatic, 2 of them with retroperitoneal hemorrhage. In all patients selective arterial embolization was performed. Permanent control of the symptoms was successful in 2 patients. In 1 patient temporary resolution of the symptoms was observed, and a second embolization was required. Retroperitoneal bleeding in 1 patient continued and nephrectomy was undertaken.

Oral 18F-fluoro-2-deoxyglucose for primate PET studies without behavioral restraint: demonstration of principle

We describe a method of orally administering 18F-fluoro-2-deoxyglucose (FDG) for positron emission tomography (PET) scans to determine local cerebral metabolic rates for glucose (LCMRGlc), normalized to that of whole brain, in fully conscious, non-restrained primates. Oral FDG-PET studies were performed in both non-restrained and chaired monkeys, and in one human where results could be compared with traditional intravenous FDG administration. The oral route of FDG administration gave images and whole brain-normalized PET LCMRGlc results comparable to those obtained by the intravenous route. This oral FDG-PET method may provide a useful means by which to obtain measures of LCMRGlcs for brain structures, relative to each other, in non-restrained, non-drugged primates in field and laboratory studies. This method might also have clinical applications for PET studies of children.

Comparison of 3-D maximum a posteriori and filtered backprojection algorithms for high-resolution animal imaging with microPET

We have evaluated the performance of two three-dimensional (3-D) reconstruction algorithms with data acquired from microPET, a high resolution tomograph dedicated to small animal imaging. The first was a linear filtered-backprojection algorithm (FBP) with reprojection of the missing data, and the second was a statistical maximum a posteriori probability algorithm (MAP). The two algorithms were evaluated in terms of their resolution performance, both in phantoms and in vivo. Sixty independent realizations of a phantom simulating the brain of a baby monkey were acquired, each containing three million counts. Each of these realizations was reconstructed independently with both algorithms. The ensemble of the 60 reconstructed realizations was used to estimate the standard deviation as a measure of the noise for each reconstruction algorithm. More detail was recovered in the MAP reconstruction without an increase in noise relative to FBP. Studies in a simple cylindrical compartment phantom demonstrated improved recovery of known activity ratios with MAP. Finally, in vivo studies also demonstrated a clear improvement in spatial resolution using the MAP algorithm. The quantitative accuracy of the MAP reconstruction was also evaluated by comparison with autoradiography and direct well counting of tissue samples and was shown to be superior.

Preoperative localization of pancreatic insulinoma by selective intraarterial calcium injection and hepatic venous sampling

Preoperative localization of insulinomas is desirable by most surgeons. Imaging with ultrasonography, computed tomography, magnetic resonance imaging, nuclear medicine and angiography may fail to demonstrate these small tumors in up to 10%, while a smaller percentage may be missed even after careful surgical exploration and intraoperative ultrasonography. Selective intraarterial injection of calcium with hepatic venous sampling has been reported to be a very accurate technique for preoperative localization of insulinomas. We report such a case where the clinical symptoms were highly suggestive but imaging algorithm failed to reveal any lesion and we review the literature.

Selective arterial embolization in the management of symptomatic renal angiomyolipomas

Current management of renal angiomyolipomas (AMLs) include observation, transcatheter embolization and partial or total nephrectomy. Patients symptoms and size of the lesion are the determinants for the choice of the treatment. In general symptomatic or greater than 8 cm masses require intervention. A retrospective study of five patients presented with symptomatic lesions and treated with selective transcatheter embolization, over a 3 year period was performed in our hospital. A total of eight embolizations were performed, all on an emergency basis due to retroperitoneal bleeding or significant hematuria. Surgical intervention was necessary in one case, due to massive rebleeding on the fourth post-procedural day. Two patients rebled within 6 months and 2 years respectively, and were managed successfully with additional embolization. The remaining two patients are still asymptomatic 26 and 18 months after the successful initial result. Experience with this procedure is reported on with emphasis to the clinical outcome. It is believed that selective arterial embolization should be the standard initial therapy for symptomatic renal AMLs.

An evaluation of exact and approximate 3-D reconstruction algorithms for a high-resolution, small-animal PET scanner

MicroPET is a low-cost, high-resolution positron emission tomography (PET) scanner designed for imaging small animals. MicroPET operates exclusively without septa, acquiring fully three-dimensional (3-D) data sets. The performance of the projection-reprojection (3DRP), variable axial rebinning (VARB), single slice rebinning (SSRB), and Fourier rebinning (FORE) methods for reconstruction of microPET data were evaluated. The algorithms were compared with respect to resolution, noise variance, and reconstruction time. Results suggested that the 3DRP algorithm gives the best combination of resolution and noise performance in 9 min of reconstruction time on a Sun UltraSparc I workstation. The FORE algorithm provided the most acceptable accelerated method of reconstruction, giving similar resolution performance with a 10%-20% degradation in noise variance in under 2 min. Significant degradation in the axial resolution was measured with the VARB and SSRB methods, offsetting the decrease in reconstruction time achieved with those methods. In-plane angular mashing of the 3-D data before reconstruction led to a 50% reduction in reconstruction time but also introduced unacceptable tangential blurring artifacts. This thorough evaluation of analytical 3-D reconstruction techniques allowed for optimal selection of a reconstruction method for the diverse range of microPET applications.

High-resolution 3D Bayesian image reconstruction using the microPET small-animal scanner

A Bayesian method is described for reconstruction of high-resolution 3D images from the microPET small-animal scanner. Resolution recovery is achieved by explicitly modelling the depth dependent geometric sensitivity for each voxel in combination with an accurate detector response model that includes factors due to photon pair non-collinearity and inter-crystal scatter and penetration. To reduce storage and computational costs we use a factored matrix in which the detector response is modelled using a sinogram blurring kernel. Maximum a posteriori (MAP) images are reconstructed using this model in combination with a Poisson likelihood function and a Gibbs prior on the image. Reconstructions obtained from point source data using the accurate system model demonstrate a potential for near-isotropic FWHM resolution of approximately 1.2 mm at the center of the field of view compared with approximately 2 mm when using an analytic 3D reprojection (3DRP) method with a ramp filter. These results also show the ability of the accurate system model to compensate for resolution loss due to crystal penetration producing nearly constant radial FWHM resolution of 1 mm out to a 4 mm radius. Studies with a point source in a uniform cylinder indicate that as the resolution of the image is reduced to control noise propagation the resolution obtained using the accurate system model is superior to that obtained using 3DRP at matched background noise levels. Additional studies using pie phantoms with hot and cold cylinders of diameter 1-2.5 mm and 18FDG animal studies appear to confirm this observation.

Mammography focal spot measurement with a star pattern: techniques to avoid inaccuracies

The increased emphasis on mammography acceptance testing and quality control make the star pattern test an essential component of the procedure for diagnosing poor resolution due to large focal spots. In this paper procedures for calculating magnification and the correct angle of the star pattern to use are described. The preferred placement of the star pattern in the field and proper exposure technique is also discussed.

Green light phototherapy in newborn infants with ABO hemolytic disease

The efficacy of fluorescent green light phototherapy was compared with that of blue light phototherapy in the treatment of full-term infants with hemolytic disease and jaundice caused by ABO incompatibility. The efficacy of the treatment was expressed as actual (milligrams per hour) and quantum (milligrams per hour per square centimeter per megawatt) efficiency, taking into account the differential emission of energy from the green versus the blue fluorescent tubes. No statistically significant difference in the rate of serum bilirubin photodegradation was found between the two groups after treatment for 84.6 +/- 14.1 hours versus 81.5 +/- 14.2 hours with the green and the blue phototherapy, respectively. These results, coupled with the known effects of the blue light on the genetic apparatus of mammalian cells, support the application of the green light phototherapy for the treatment of neonatal hyperbilirubinemia caused by ABO incompatibility.

On the notion of doll's eyes

CD90 is a membrane GPI-anchored protein with one Ig V-type superfamily domain that was initially described in mouse T cells. Besides the specific expression pattern and functions of CD90 that were described in normal tissues, i.e., neurons, fibroblasts and T cells, increasing evidences are currently highlighting the possible involvement of CD90 in cancer. This review first provides a brief overview on CD90 gene, mRNA and protein features and then describes the established links between CD90 and cancer. Finally, we report newly uncovered functional connections between CD90 and endoplasmic reticulum (ER) stress signaling and discuss their potential impact on cancer development.