The in vitro dynamics of pseudo-vascular network formation.

BACKGROUND/OBJECTIVES: Pseudo-vascular network formation in vitro is considered a key characteristic of vasculogenic mimicry. While many cancer cell lines form pseudo-vascular networks, little is known about the spatiotemporal dynamics of these formations. METHODS: Here, we present a framework for monitoring and characterising the dynamic formation and dissolution of pseudo-vascular networks in vitro. The framework combines time-resolved optical microscopy with open-source image analysis for network feature extraction and statistical modelling. The framework is demonstrated by comparing diverse cancer cell lines associated with vasculogenic mimicry, then in detecting response to drug compounds proposed to affect formation of vasculogenic mimics. Dynamic datasets collected were analysed morphometrically and a descriptive statistical analysis model was developed in order to measure stability and dissimilarity characteristics of the pseudo-vascular networks formed. RESULTS: Melanoma cells formed the most stable pseudo-vascular networks and were selected to evaluate the response of their pseudo-vascular networks to treatment with axitinib, brucine and tivantinib. Tivantinib has been found to inhibit the formation of the pseudo-vascular networks more effectively, even in dose an order of magnitude less than the two other agents. CONCLUSIONS: Our framework is shown to enable quantitative analysis of both the capacity for network formation, linked vasculogenic mimicry, as well as dynamic responses to treatment.

The decline in transurethral resection of the prostate gland in Irish public hospitals between 2005 and 2021.

BACKGROUND: Lower urinary tract symptoms due to an enlarged prostate is a common condition. Transurethral resection of the prostate gland (TURP) has been the gold standard treatment. The objective of this study was to assess the trends in the prevalence of TURP procedures in Irish public hospitals within the period of 2005-2021. In addition, we explore the attitudes and practices of urologist in Ireland on this topic. METHODS: An analysis using the Hospital In-Patient Enquiry (HIPE) system using code 37203-00 was undertaken. 16,176 discharges contained the code of interest and had undergone a TURP procedure. The data from this cohort was further analysed. In addition, members of the Irish Society of Urology undertook a bespoke questionnaire to understand the TURP surgery practices. RESULTS: There has been a substantial decline in the prevalence of TURP procedures in Irish public hospitals from 2005 to 2021. The number of patients discharged from Irish hospitals with a TURP procedure was 66% less in 2021 compared to 2005. 75% (n = 36) of urologist surveyed felt that the declining TURP numbers were due to lack of resources, access to theatre/inpatient beds and outsourcing. 91.5% (n = 43) felt that the declining TURP numbers would result in a lack of training opportunities for trainees, 83% (39) felt this has increased morbidity for patients. CONCLUSIONS: TURP procedures in Irish public hospitals has declined over the 16-year period studied. This decline is a concern for patient morbidity and urology training.

'I Had It. I Don't Think I Have It But I Do Feel It Will Come Back Somewhere': A Qualitative Investigation of the Experience of People With Non-Muscle Invasive Bladder Cancer.

Very little is known about the impact of living with non-muscle invasive bladder cancer (NMIBC). NMIBC patients' experiences of their illness-in terms of their perceptions, coping strategies and psychological wellbeing-were explored. This study describes an interpretative phenomenological analysis (IPA) of individuals' accounts of living with NMIBC while on routine surveillance for cancer recurrence. Ten individuals took part in face-to-face semi-structured interviews. Three superordinate themes were derived from the data. The first theme, Being Diagnosed and Treated for NMIBC, concerned the observation that participants considered the physical implications, timeline and practicalities of their illness of primary importance and focused less on its psychological aspects. The second theme, Grappling with the Illness, outlined the impact of the doctor-patient relationship. The final theme, 'I don't treat it as a problem. I treat it as an issue', delineated how participants managed difficult emotions in the context of the illness. Findings from this study demonstrated that participants generally found effective ways to cope with their illness and experience of ongoing surveillance, though delay of emotional responses was common. Clinical implications for healthcare professionals are outlined including the importance of high-quality communication with the urology team.

Patient reported factors influencing the decision-making process of men with localised prostate cancer when considering Active Surveillance-A systematic review and thematic synthesis.

OBJECTIVES: Outcomes for men with localised prostate cancer managed with Active Surveillance (AS) are similar to outcomes for men who have received Active Treatment. This review explore men's perceptions of the factors that influence their decision-making process when considering AS. METHOD: A systematic review of studies was conducted up to May 2021, including qualitative studies which explored the decision making of men with localised prostate cancer when considering AS. Evidence was analysed using thematic synthesis. RESULTS: Thirteen papers, including 426 men, met inclusion criteria and were analysed in the review. Approximately half of the men had chosen AS and half had chosen Active Treatment. The choice of AS was not a one-off decision but rather an ongoing behaviour. Four themes were identified and considered within a temporal model: pre-diagnosis representations of cancer and treatment; experience of testing and diagnosis; patient decision making; and emotional adjustment to AS. Key barriers and facilitators to men choosing AS were identified. In deciding whether or not to choose AS, men balanced a desire for quality of life against fear of cancer progression. CONCLUSIONS: Both cognitive representations and emotional arousal influence how men decided whether or not to opt for AS. Interventions tailored to elicit and address emotional appraisals of risk, and increase trust in AS protocols, may be of value in helping men to make decisions around treatment for localised prostate cancer.

Heterogeneity in biological assemblages and exposure in chemical risk assessment: Exploring capabilities and challenges in methodology with two landscape-scale case studies.

Chemical exposure concentrations and the composition of ecological receptors (e.g., species) vary in space and time, resulting in landscape-scale (e.g. catchment) heterogeneity. Current regulatory, prospective chemical risk assessment frameworks do not directly address this heterogeneity because they assume that reasonably worst-case chemical exposure concentrations co-occur (spatially and temporally) with biological species that are the most sensitive to the chemical's toxicity. Whilst current approaches may parameterise fate models with site-specific data and aim to be protective, a more precise understanding of when and where chemical exposure and species sensitivity co-occur enables risk assessments to be better tailored and applied mitigation more efficient. We use two aquatic case studies covering different spatial and temporal resolution to explore how geo-referenced data and spatial tools might be used to account for landscape heterogeneity of chemical exposure and ecological assemblages in prospective risk assessment. Each case study followed a stepwise approach: i) estimate and establish spatial chemical exposure distributions using local environmental information and environmental fate models; ii) derive toxicity thresholds for different taxonomic groups and determine geo-referenced distributions of exposure-toxicity ratios (i.e., potential risk); iii) overlay risk data with the ecological status of biomonitoring sites to determine if relationships exist. We focus on demonstrating whether the integration of relevant data and potential approaches is feasible rather than making comprehensive and refined risk assessments of specific chemicals. The case studies indicate that geo-referenced predicted environmental concentration estimations can be achieved with available data, models and tools but establishing the distribution of species assemblages is reliant on the availability of a few sources of biomonitoring data and tools. Linking large sets of geo-referenced exposure and biomonitoring data is feasible but assessment of risk will often be limited by the availability of ecotoxicity data. The studies highlight the important influence that choices for aggregating data and for the selection of statistical metrics have on assessing and interpreting risk at different spatial scales and patterns of distribution within the landscape. Finally, we discuss approaches and development needs that could help to address environmental heterogeneity in chemical risk assessment.

Modelling the transport of fluid through heterogeneous, whole tumours in silico.

Cancers exhibit spatially heterogeneous, unique vascular architectures across individual samples, cell-lines and patients. This inherently disorganised collection of leaky blood vessels contribute significantly to suboptimal treatment efficacy. Preclinical tools are urgently required which incorporate the inherent variability and heterogeneity of tumours to optimise and engineer anti-cancer therapies. In this study, we present a novel computational framework which incorporates whole, realistic tumours extracted ex vivo to efficiently simulate vascular blood flow and interstitial fluid transport in silico for validation against in vivo biomedical imaging. Our model couples Poiseuille and Darcy descriptions of vascular and interstitial flow, respectively, and incorporates spatially heterogeneous blood vessel lumen and interstitial permeabilities to generate accurate predictions of tumour fluid dynamics. Our platform enables highly-controlled experiments to be performed which provide insight into how tumour vascular heterogeneity contributes to tumour fluid transport. We detail the application of our framework to an orthotopic murine glioma (GL261) and a human colorectal carcinoma (LS147T), and perform sensitivity analysis to gain an understanding of the key biological mechanisms which determine tumour fluid transport. Finally we mimic vascular normalization by modifying parameters, such as vascular and interstitial permeabilities, and show that incorporating realistic vasculatures is key to modelling the contrasting fluid dynamic response between tumour samples. Contrary to literature, we show that reducing tumour interstitial fluid pressure is not essential to increase interstitial perfusion and that therapies should seek to develop an interstitial fluid pressure gradient. We also hypothesise that stabilising vessel diameters and permeabilities are not key responses following vascular normalization and that therapy may alter interstitial hydraulic conductivity. Consequently, we suggest that normalizing the interstitial microenvironment may provide a more effective means to increase interstitial perfusion within tumours.

A knowledge-based approach to designing control strategies for agricultural pests.

Chemical control of insect pests remains vital to agricultural productivity, but limited mechanistic understanding of the interactions between crop, pest and chemical control agent have restricted our capacity to respond to challenges such as the emergence of resistance and demands for tighter environmental regulation. Formulating effective control strategies that integrate chemical and non-chemical management for soil-dwelling pests is particularly problematic owing to the complexity of the soil-root-pest system and the variability that occurs between sites and between seasons. Here, we present a new concept, termed COMPASS, that integrates ecological knowledge on pest development and behaviour together with crop physiology and mechanistic understanding of chemical distribution and toxic action within the rhizosphere. The concept is tested using a two-dimensional systems model (COMPASS-Rootworm) that simulates root damage in maize from the corn rootworm Diabrotica spp. We evaluate COMPASS-Rootworm using 119 field trials that investigated the efficacy of insecticidal products and placement strategies at four sites in the USA over a period of ten years. Simulated root damage is consistent with measurements for 109 field trials. Moreover, we disentangle factors influencing root damage and pest control, including pest pressure, weather, insecticide distribution, and temporality between the emergence of crop roots and pests. The model can inform integrated pest management, optimize pest control strategies to reduce environmental burdens from pesticides, and improve the efficiency of insecticide development.

Multiple Scale Homogenisation of Nutrient Movement and Crop Growth in Partially Saturated Soil.

In this paper, we use multiple scale homogenisation to derive a set of averaged macroscale equations that describe the movement of nutrients in partially saturated soil that contains growing potato tubers. The soil is modelled as a poroelastic material, which is deformed by the growth of the tubers, where the growth of each tuber is dependent on the uptake of nutrients via a sink term within the soil representing root nutrient uptake. Special attention is paid to the reduction in void space, resulting change in local water content and the impact on nutrient diffusion within the soil as the tubers increase in size. To validate the multiple scale homogenisation procedure, we compare the system of homogenised equations to the original set of equations and find that the solutions between the two models differ by [Formula: see text]. However, we find that the computation time between the two sets of equations differs by several orders of magnitude. This is due to the combined effects of the complex three-dimensional geometry and the implementation of a moving boundary condition to capture tuber growth.

Minimising the risk of Mycobacterium chimaera infection during cardiopulmonary bypass by the removal of heater-cooler units from the operating room.

INTRODUCTION: Mycobacterium chimaera ( M. chimaera) is a recently characterised bacterium that can cause life-threatening infections in small numbers of patients who undergo cardiopulmonary bypass during cardiac surgery. The likely mode of transmission is thought to occur through aerosolisation from contaminated water reservoirs. The airborne bacteria then contaminate the surgical field, leading to an infection months or even years later. The preferred practical solution to disrupt the transmission of these airborne bacteria to the patient is to remove the heater-cooler units (HCUs) from the operating room (OR). We describe a process of achieving this in order to provide information to guide other institutions who wish to do a similar thing. METHODS: A multidisciplinary team was assembled to work on the project. The planning phase involved trialling different OR layouts and simulating the alterations in the HCU circuit function. The changes to the OR were made over a weekend to minimise disruption to the operating schedule. RESULTS: The HCU was moved to the dirty utility room adjacent to the OR. Standard operating procedures (SOP) and risk assessments were made to enable this to be used for a dual purpose. One of the ORs was reconfigured to allow the cardiopulmonary bypass machine to be located close to the HCU in the dirty utility room. The total cost of the alterations was £6,158. Although we have provided a physical barrier to interrupt patient exposure to aerosolised M. chimaera from HCUs, we continue to perform cultures and decontamination as per the national recommendations. The SOP was designed to be auditable to ensure compliance with the protocols. CONCLUSIONS: We show a method by which the HCU can be removed from the OR in a relatively low-cost, straightforward and practical manner.

A Prospective Study of Total Glans Resurfacing for Localized Penile Cancer to Maximize Oncologic and Functional Outcomes in a Tertiary Referral Network.

PURPOSE: Penile cancer is a rare malignancy worldwide, representing only 1% of all cancers affecting men. There are little data outlining the comparative effectiveness of penile preservation techniques and to our knowledge no guidelines regarding their use currently exist. Outcomes data reporting is nonstandardized and followup is not measured consistently. The aim of this study was to analyze the outcomes of total glans resurfacing in terms of oncologic control, form and function in localized penile cancer. MATERIALS AND METHODS: From 2013 to 2015, 19 prospectively enrolled patients underwent total glans resurfacing. Demographics, cosmesis, patient satisfaction and disease recurrence were assessed at followup to quantify oncologic and functional outcomes. At 3 months of followup patients completed the IIEF (International Index of Erectile Function) questionnaire detailing erectile and sexual function, and general satisfaction using a visual analog scale. All statistical analysis was performed with Prism® 6. RESULTS: No perioperative complications were experienced. Of the patients 94.7% had complete graft take with a median cosmesis score of 5 of 5 on the visual analog scale. There was 1 local and no regional nodal recurrence at a mean followup of 23 months. One-year progression-free and overall survival rates were 100% and the 1-year recurrence-free survival rate was 95%. Of the patients 81% reported an improved sex life postoperatively. CONCLUSIONS: Total glans resurfacing is a viable and acceptable option for glans preservation in patients with localized penile cancer. It demonstrates acceptable functional and oncologic outcomes. We believe that total glans resurfacing should be considered in all cases of localized penile cancer.

Polyene macrolide biosynthesis in streptomycetes and related bacteria: recent advances from genome sequencing and experimental studies.

The polyene macrolide group includes important antifungal drugs, to which resistance does not arise readily. Chemical and biological methods have been used in attempts to make polyene antibiotics with fewer toxic side effects. Genome sequencing of producer organisms is contributing to this endeavour, by providing access to new compounds and by enabling yield improvement for polyene analogues obtained by engineered biosynthesis. This recent work is also enhancing bioinformatic methods for deducing the structures of cryptic natural products from their biosynthetic enzymes. The stereostructure of candicidin D has recently been determined by NMR spectroscopy. Genes for the corresponding polyketide synthase have been uncovered in several different genomes. Analysis of this new information strengthens the view that protein sequence motifs can be used to predict double bond geometry in many polyketides.Chemical studies have shown that improved polyenes can be obtained by modifying the mycosamine sugar that is common to most of these compounds. Glycoengineered analogues might be produced by biosynthetic methods, but polyene glycosyltransferases show little tolerance for donors other than GDP-α-D-mycosamine. Genome sequencing has revealed extending glycosyltransferases that add a second sugar to the mycosamine of some polyenes. NppY of Pseudonocardia autotrophica uses UDP-N-acetyl-α-D-glucosamine as donor whereas PegA from Actinoplanes caeruleus uses GDP-α-D-mannose. These two enzymes show 51 % sequence identity and are also closely related to mycosaminyltransferases. These findings will assist attempts to construct glycosyltransferases that transfer alternative UDP- or (d)TDP-linked sugars to polyene macrolactones.

Exploiting the genome sequence of Streptomyces nodosus for enhanced antibiotic production.

The genome of the amphotericin producer Streptomyces nodosus was sequenced. A single scaffold of 7,714,110 bp was obtained. Biosynthetic genes were identified for several natural products including polyketides, peptides, siderophores and terpenes. The majority of these clusters specified known compounds. Most were silent or expressed at low levels and unlikely to compete with amphotericin production. Biosynthesis of a skyllamycin analogue was activated by introducing expression plasmids containing either a gene for a LuxR transcriptional regulator or genes for synthesis of the acyl moiety of the lipopeptide. In an attempt to boost amphotericin production, genes for acyl CoA carboxylases, a phosphopantetheinyl transferase and the AmphRIV transcriptional activator were overexpressed, and the effects on yields were investigated. This study provides the groundwork for metabolic engineering of S. nodosus strains to produce high yields of amphotericin analogues.

A three-dimensional, discrete-continuum model of blood pressure in microvascular networks.

We present a 3D discrete-continuum model to simulate blood pressure in large microvascular tissues in the absence of known capillary network architecture. Our hybrid approach combines a 1D Poiseuille flow description for large, discrete arteriolar and venular networks coupled to a continuum-based Darcy model, point sources of flux, for transport in the capillary bed. We evaluate our hybrid approach using a vascular network imaged from the mouse brain medulla/pons using multi-fluorescence high-resolution episcopic microscopy (MF-HREM). We use the fully-resolved vascular network to predict the hydraulic conductivity of the capillary network and generate a fully-discrete pressure solution to benchmark against. Our results demonstrate that the discrete-continuum methodology is a computationally feasible and effective tool for predicting blood pressure in real-world microvascular tissues when capillary microvessels are poorly defined.

Moving Beyond Simulation: Data-Driven Quantitative Photoacoustic Imaging Using Tissue-Mimicking Phantoms.

Accurate measurement of optical absorption coefficients from photoacoustic imaging (PAI) data would enable direct mapping of molecular concentrations, providing vital clinical insight. The ill-posed nature of the problem of absorption coefficient recovery has prohibited PAI from achieving this goal in living systems due to the domain gap between simulation and experiment. To bridge this gap, we introduce a collection of experimentally well-characterised imaging phantoms and their digital twins. This first-of-a-kind phantom data set enables supervised training of a U-Net on experimental data for pixel-wise estimation of absorption coefficients. We show that training on simulated data results in artefacts and biases in the estimates, reinforcing the existence of a domain gap between simulation and experiment. Training on experimentally acquired data, however, yielded more accurate and robust estimates of optical absorption coefficients. We compare the results to fluence correction with a Monte Carlo model from reference optical properties of the materials, which yields a quantification error of approximately 20%. Application of the trained U-Nets to a blood flow phantom demonstrated spectral biases when training on simulated data, while application to a mouse model highlighted the ability of both learning-based approaches to recover the depth-dependent loss of signal intensity. We demonstrate that training on experimental phantoms can restore the correlation of signal amplitudes measured in depth. While the absolute quantification error remains high and further improvements are needed, our results highlight the promise of deep learning to advance quantitative PAI.

Unsupervised Segmentation of 3D Microvascular Photoacoustic Images Using Deep Generative Learning.

Mesoscopic photoacoustic imaging (PAI) enables label-free visualization of vascular networks in tissues with high contrast and resolution. Segmenting these networks from 3D PAI data and interpreting their physiological and pathological significance is crucial yet challenging due to the time-consuming and error-prone nature of current methods. Deep learning offers a potential solution; however, supervised analysis frameworks typically require human-annotated ground-truth labels. To address this, an unsupervised image-to-image translation deep learning model is introduced, the Vessel Segmentation Generative Adversarial Network (VAN-GAN). VAN-GAN integrates synthetic blood vessel networks that closely resemble real-life anatomy into its training process and learns to replicate the underlying physics of the PAI system in order to learn how to segment vasculature from 3D photoacoustic images. Applied to a diverse range of in silico, in vitro, and in vivo data, including patient-derived breast cancer xenograft models and 3D clinical angiograms, VAN-GAN demonstrates its capability to facilitate accurate and unbiased segmentation of 3D vascular networks. By leveraging synthetic data, VAN-GAN reduces the reliance on manual labeling, thus lowering the barrier to entry for high-quality blood vessel segmentation (F1 score: VAN-GAN vs. U-Net = 0.84 vs. 0.87) and enhancing preclinical and clinical research into vascular structure and function.

Performance evaluation of mesoscopic photoacoustic imaging.

Photoacoustic mesoscopy visualises vascular architecture at high-resolution up to ~3 mm depth. Despite promise in preclinical and clinical imaging studies, with applications in oncology and dermatology, the accuracy and precision of photoacoustic mesoscopy is not well established. Here, we evaluate a commercial photoacoustic mesoscopy system for imaging vascular structures. Typical artefact types are first highlighted and limitations due to non-isotropic illumination and detection are evaluated with respect to rotation, angularity, and depth of the target. Then, using tailored phantoms and mouse models, we investigate system precision, showing coefficients of variation (COV) between repeated scans [short term (1 h): COV= 1.2%; long term (25 days): COV= 9.6%], from target repositioning (without: COV=1.2%, with: COV=4.1%), or from varying in vivo user experience (experienced: COV=15.9%, unexperienced: COV=20.2%). Our findings show robustness of the technique, but also underscore general challenges of limited-view photoacoustic systems in accurately imaging vessel-like structures, thereby guiding users when interpreting biologically-relevant information.

DNA vaccination for prostate cancer, from preclinical to clinical trials - where we stand?

Development of various vaccines for prostate cancer (PCa) is becoming an active research area. PCa vaccines are perceived to have less toxicity compared with the available cytotoxic agents. While various immune-based strategies can elicit anti-tumour responses, DNA vaccines present increased efficacy, inducing both humoural and cellular immunity. This immune activation has been proven effective in animal models and initial clinical trials are encouraging. However, to validate the role of DNA vaccination in currently available PCa management paradigms, strong clinical evidence is still lacking. This article provides an overview of the basic principles of DNA vaccines and aims to provide a summary of preclinical and clinical trials outlining the benefits of this immunotherapy in the management of PCa.

Assessment of intrinsic aquifer vulnerability at continental scale through a critical application of the drastic framework: The case of South America.

An assessment of the intrinsic aquifer vulnerability of South America is presented. The outcomes represent the potential sensitivity of natural aquifers to leaching of dissolved compounds from the land surface. The study, developed at continental scale but retaining regionally a high resolution, is based on a critical application of the DRASTIC method. The biggest challenge in performing such a study in South America was the scattered and irregular nature of environmental datasets. Accordingly, the most updated information on soil, land use, geology, hydrogeology, and climate at continental, national, and regional scale were selected from international and local databases. To avoid spatial discrepancy and inconsistency, data were integrated, harmonized, and accurately cross-checked, using local professional knowledge where information was missing. The method was applied in a GIS environment to allow spatial analysis of raw data along with the overlaying and rating of maps. The application of the DRASTIC method allows to classify South America into five vulnerability classes, from very low to very high, and shows an overall medium to low vulnerability at continental scale. The Amazon region, coastal aquifers, colluvial Andean valleys, and alluvial aquifers of main rivers were the areas classified as highly vulnerable. Moreover, countries with the largest areas with high aquifer vulnerability were those characterized by extended regions of rainforest. In addition, a single parameter sensitivity analysis showed depth to water table to be the most significant factor, while a cross-validation using existing vulnerability assessments and observed concentrations of compounds in groundwater confirmed the reliability of the proposed assessment, even at regional scale. Overall, although additional field surveys and detailed works at local level are needed to develop effective water management plans, the present DRASTIC map represents an essential common ground towards a more sustainable land-use and water management in the whole territory of South America.

Quantification of vascular networks in photoacoustic mesoscopy.

Mesoscopic photoacoustic imaging (PAI) enables non-invasive visualisation of tumour vasculature. The visual or semi-quantitative 2D measurements typically applied to mesoscopic PAI data fail to capture the 3D vessel network complexity and lack robust ground truths for assessment of accuracy. Here, we developed a pipeline for quantifying 3D vascular networks captured using mesoscopic PAI and tested the preservation of blood volume and network structure with topological data analysis. Ground truth data of in silico synthetic vasculatures and a string phantom indicated that learning-based segmentation best preserves vessel diameter and blood volume at depth, while rule-based segmentation with vesselness image filtering accurately preserved network structure in superficial vessels. Segmentation of vessels in breast cancer patient-derived xenografts (PDXs) compared favourably to ex vivo immunohistochemistry. Furthermore, our findings underscore the importance of validating segmentation methods when applying mesoscopic PAI as a tool to evaluate vascular networks in vivo.

Induction of effective antitumor response after mucosal bacterial vector mediated DNA vaccination with endogenous prostate cancer specific antigen.

PURPOSE: The induction of systemic immune responses against antigenic targets that are over expressed by cancer cells represents a powerful therapeutic strategy to target metastatic cancer. We generated specific antitumor immune responses in a murine model of prostate cancer by oral administration of an attenuated strain of Salmonella typhimurium containing a plasmid coding for murine prostate stem cell antigen. MATERIALS AND METHODS: Trafficking of S. typhimurium SL7207 in the initial 10 hours after gavage feeding was determined using a bacterial lux expressing strain and live bioluminescence imaging. For vaccination trials male C57 BL/6 mice were gavage fed SL7207/murine prostate stem cell antigen expressing plasmid or controls twice at 2-week intervals. One week after the last feeding the mice were challenged subcutaneously with TRAMPC1 murine prostate carcinoma cells. Tumor dynamics and animal survival were recorded. RESULTS: Clearance of bacterial vector from animals was complete 9 hours after feeding. Delivery of vector transformed with a firefly luciferase reporter plasmid resulted in maximal eukaryotic reporter gene expression in splenocytes 48 hours after feeding. Induction of tumor protective immunity was achieved by feeding the mice murine prostate stem cell antigen expressing plasmid bearing bacteria and greater than 50% of immunized mice remained tumor free. No significant toxicity was observed. Induction of T-helper type 1 immune responses was determined by measuring interferon-γ produced by splenocytes from vaccinated mice. When adoptively transferred to naive animals, splenocytes from vaccinated mice prevented tumor growth in 66% of challenged animals. CONCLUSIONS: Endogenous prostate cancer antigen gene delivery using a bacterial vector resulted in breaking immune tolerance to murine prostate stem cell antigen and significant retardation of tumor growth.