Tissue-resident memory T cells are epigenetically cytotoxic with signs of exhaustion in human urinary bladder cancer.

Tissue-resident memory T (TRM ) cells are CD8+ T lymphocytes that reside in the tissues, including tumours. This T cell subset possesses a magnitude of cytotoxicity, but its epigenetic regulation has not been studied. Here, we investigate the impact of perforin DNA methylation in TRM cells and correlate it with their functional potential. Fifty-three urothelial urinary bladder cancer (UBC) patients were recruited prospectively. The DNA methylation status of the perforin gene (PRF1) locus in TRM cells was investigated by pyrosequencing. Flow cytometry with ViSNE analysis and in-vitro stimulation were used to evaluate TRM cell phenotypes. We discovered that tumour TRM cells have low DNA methylation in the PRF1 locus (32·9% methylation), which corresponds to increased numbers of perforin-expressing TRM cells. Surprisingly, programmed cell death 1 (PD-1) expression is high in tumour TRM cells, suggesting exhaustion. Following interleukin-15 and T cell receptor stimulation, perforin and T-bet expressions are enhanced, indicating that TRM cells from tumours are not terminally exhausted. Moreover, a high number of TRM cells infiltrating the tumours corresponds to lower tumour stage in patients. In conclusion, TRM cells from UBC tumours are epigenetically cytotoxic with signs of exhaustion. This finding identifies TRM cells as potential new targets for cancer immunotherapy.

Combined PET/MRI: Global Warming-Summary Report of the 6th International Workshop on PET/MRI, March 27-29, 2017, Tübingen, Germany.

The 6th annual meeting to address key issues in positron emission tomography (PET)/magnetic resonance imaging (MRI) was held again in Tübingen, Germany, from March 27 to 29, 2017. Over three days of invited plenary lectures, round table discussions and dialogue board deliberations, participants critically assessed the current state of PET/MRI, both clinically and as a research tool, and attempted to chart future directions. The meeting addressed the use of PET/MRI and workflows in oncology, neurosciences, infection, inflammation and chronic pain syndromes, as well as deeper discussions about how best to characterise the tumour microenvironment, optimise the complementary information available from PET and MRI, and how advanced data mining and bioinformatics, as well as information from liquid biomarkers (circulating tumour cells and nucleic acids) and pathology, can be integrated to give a more complete characterisation of disease phenotype. Some issues that have dominated previous meetings, such as the accuracy of MR-based attenuation correction (AC) of the PET scan, were finally put to rest as having been adequately addressed for the majority of clinical situations. Likewise, the ability to standardise PET systems for use in multicentre trials was confirmed, thus removing a perceived barrier to larger clinical imaging trials. The meeting openly questioned whether PET/MRI should, in all cases, be used as a whole-body imaging modality or whether in many circumstances it would best be employed to give an in-depth study of previously identified disease in a single organ or region. The meeting concluded that there is still much work to be done in the integration of data from different fields and in developing a common language for all stakeholders involved. In addition, the participants advocated joint training and education for individuals who engage in routine PET/MRI. It was agreed that PET/MRI can enhance our understanding of normal and disrupted biology, and we are in a position to describe the in vivo nature of disease processes, metabolism, evolution of cancer and the monitoring of response to pharmacological interventions and therapies. As such, PET/MRI is a key to advancing medicine and patient care.

Simulating effects of brain atrophy in longitudinal PET imaging with an anthropomorphic brain phantom.

In longitudinal positron emission tomography (PET), the presence of volumetric changes over time can lead to an overestimation or underestimation of the true changes in the quantified PET signal due to the partial volume effect (PVE) introduced by the limited spatial resolution of existing PET cameras and reconstruction algorithms. Here, a 3D-printed anthropomorphic brain phantom with attachable striata in three sizes was designed to enable controlled volumetric changes. Using a method to eliminate the non-radioactive plastic wall, and manipulating BP levels by adding different number of events from list-mode acquisitions, we investigated the artificial volume dependence of BP due to PVE, and potential bias arising from varying BP. Comparing multiple reconstruction algorithms we found that a high-resolution ordered-subsets maximization algorithm with spatially variant point-spread function resolution modeling provided the most accurate data. For striatum, the BP changed by 0.08% for every 1% volume change, but for smaller volumes such as the posterior caudate the artificial change in BP was as high as 0.7% per 1% volume change. A simple gross correction for striatal volume is unsatisfactory, as the amplitude of the PVE on the BP differs depending on where in the striatum the change occurred. Therefore, to correctly interpret age-related longitudinal changes in the BP, we must account for volumetric changes also within a structure, rather than across the whole volume. The present 3D-printing technology, combined with the wall removal method, can be implemented to gain knowledge about the predictable bias introduced by the PVE differences in uptake regions of varying shape.

Combined PET/MRI: from Status Quo to Status Go. Summary Report of the Fifth International Workshop on PET/MR Imaging; February 15-19, 2016; Tübingen, Germany.

This article provides a collaborative perspective of the discussions and conclusions from the fifth international workshop of combined positron emission tomorgraphy (PET)/magnetic resonance imaging (MRI) that was held in Tübingen, Germany, from February 15 to 19, 2016. Specifically, we summarise the second part of the workshop made up of invited presentations from active researchers in the field of PET/MRI and associated fields augmented by round table discussions and dialogue boards with specific topics. This year, this included practical advice as to possible approaches to moving PET/MRI into clinical routine, the use of PET/MRI in brain receptor imaging, in assessing cardiovascular diseases, cancer, infection, and inflammatory diseases. To address perceived challenges still remaining to innovatively integrate PET and MRI system technologies, a dedicated round table session brought together key representatives from industry and academia who were engaged with either the conceptualisation or early adoption of hybrid PET/MRI systems. Discussions during the workshop highlighted that emerging unique applications of PET/MRI such as the ability to provide multi-parametric quantitative and visual information which will enable not only overall disease detection but also disease characterisation would eventually be regarded as compelling arguments for the adoption of PET/MR. However, as indicated by previous workshops, evidence in favour of this observation is only growing slowly, mainly due to the ongoing inability to pool data cohorts from independent trials as well as different systems and sites. The participants emphasised that moving from status quo to status go entails the need to adopt standardised imaging procedures and the readiness to act together prospectively across multiple PET/MRI sites and vendors.

Radiation Dose to Patients from Radiopharmaceuticals: a Compendium of Current Information Related to Frequently Used Substances.

This report provides a compendium of current information relating to radiation dose to patients, including biokinetic models, biokinetic data, dose coefficients for organ and tissue absorbed doses, and effective dose for major radiopharmaceuticals based on the radiation protection guidance given in Publication 60(ICRP, 1991). These data were mainly compiled from Publications 53, 80, and 106(ICRP, 1987, 1998, 2008), and related amendments and corrections. This report also includes new information for 82Rb-chloride, iodide (123I, 124I, 125I, and 131I) and 123I labeled 2ß-carbomethoxy 3ß-(4-iodophenyl)-N-(3-fluoropropyl) nortropane (FPCIT).The coefficients tabulated in this publication will be superseded in due course by values calculated using new International Commission on Radiation Units and Measurements/International Commission on Radiological Protection adult and paediatric reference phantoms and Publication 103 methodology (ICRP,2007). The data presented in this report are intended for diagnostic nuclear medicine and not for therapeutic applications.

COBRA: A prospective multimodal imaging study of dopamine, brain structure and function, and cognition.

Cognitive decline is a characteristic feature of normal human aging. Previous work has demonstrated marked interindividual variability in onset and rate of decline. Such variability has been linked to factors such as maintenance of functional and structural brain integrity, genetics, and lifestyle. Still, few, if any, studies have combined a longitudinal design with repeated multimodal imaging and a comprehensive assessment of cognition as well as genetic and lifestyle factors. The present paper introduces the Cognition, Brain, and Aging (COBRA) study, in which cognitive performance and brain structure and function are measured in a cohort of 181 older adults aged 64 to 68 years at baseline. Participants will be followed longitudinally over a 10-year period, resulting in a total of three equally spaced measurement occasions. The measurement protocol at each occasion comprises a comprehensive set of behavioral and imaging measures. Cognitive performance is evaluated via computerized testing of working memory, episodic memory, perceptual speed, motor speed, implicit sequence learning, and vocabulary. Brain imaging is performed using positron emission tomography with [(11)C]-raclopride to assess dopamine D2/D3 receptor availability. Structural magnetic resonance imaging (MRI) is used for assessment of white and gray-matter integrity and cerebrovascular perfusion, and functional MRI maps brain activation during rest and active task conditions. Lifestyle descriptives are collected, and blood samples are obtained and stored for future evaluation. Here, we present selected results from the baseline assessment along with a discussion of sample characteristics and methodological considerations that determined the design of the study. This article is part of a Special Issue entitled SI: Memory & Aging.

Association of adipose tissue blood flow with fat depot sizes and adipokines in women.

OBJECTIVE: To explore possible associations between adipose tissue (AT) blood flow (ATBF), AT depot sizes and adipocyte-derived hormones (adipokines) in women. SUBJECTS: In all, 43 healthy women were divided into four groups: normal-weight (n=11) and obese (n=11) pre-menopausal women and normal-weight (n=10) and obese (n=11) post-menopausal women. METHODS: Fasting levels of adipokines were obtained, and a single-slice computed tomography scan at the level of L4-L5 was used to estimate fat depot sizes. ATBF was assessed by xenon washout while in a fasting state and after oral glucose load. We also measured glucose, insulin and non-esterified fatty acids. RESULTS: Total, subcutaneous and visceral AT areas strongly correlated with ATBF (all P<0.001). Circulating leptin levels strongly and inversely correlated with ATBF (P=0.001), but this association did not remain after adjustment for body mass index. Adiponectin was not associated with blood flow. CONCLUSION: ATBF is closely linked to subcutaneous and visceral AT size. Further analyses are needed to determine possible mediators of this association, including mechanistic studies to assess a putative role for leptin as a significant modulator of blood flow.

Ultrasound, computed tomography, and laboratory findings in the diagnosis of appendicitis.

PURPOSE: To determine the diagnostic accuracy and the clinical impact of ultrasound (US) and computed tomography (CT) in diagnosing appendicitis, and to evaluate the impact of laboratory tests on the treatment of acute appendicitis. MATERIAL AND METHODS: All patients who, during 2005, underwent an acute ultrasound or CT investigation due to suspected appendicitis, or were diagnosed and/or surgically treated for appendicitis at Umeå University Hospital, Umeå, were included. The type of radiological investigation, its findings, the choice of treatment, final diagnosis, C-reactive protein (CRP), leukocyte particle count (LPC), body temperature, age, and sex were recorded for each patient. The histological result from surgery was considered the gold standard. RESULTS: The material included 305 cases with an overall appendicitis prevalence of 58%. Fifty-two percent of the patients were female. The mean age was 29 years, with a total range of 2-94 years. Twenty percent (60/305) underwent a CT investigation, 40% (123/305) underwent an US investigation, 5% (14/305) underwent both a CT and an US investigation, and 35% (108/305) of patients did not undergo any radiological investigation at all. The sensitivities and specificities were 91% and 94% for CT, and 83% and 98% for US, respectively. The positive likelihood ratio was 15.1 and 45.5 for CT and US, and the negative likelihood ratio was 0.09 and 0.18 for CT and US, respectively. It was not possible to visualize the appendix in 31% of patients examined with US. The prevalence of appendicitis in this group was the same as the prevalence among patients where it was possible to see the appendix, i.e., 35%. The mean CRP for all patients with appendicitis was 59 (95% CI 10-491) mg/l, and the mean LPC was 11.1 (95% CI 2.6-28.1) x10(-9)/l. The mean LPC level was significantly higher for the appendicitis patients. Body temperature could not significantly verify or exclude appendicitis. The overall negative appendectomy rate was 9% (16/176), and it was higher in women, i.e., 11% (9/79). The negative appendectomy rate was slightly higher in the group that was examined by CT and/or US, i.e., 12% (8/69) compared to 7% (8/107) in the group not examined radiologically. CONCLUSION: Diagnostic accuracy was high for US as well as for CT. US was better for diagnosing positive findings, while CT was better for excluding diagnosis of appendicitis. The diagnostic accuracy of LPC, CRP, and body temperature was low. By combining findings from the radiological examination with the results from the clinical examination and laboratory values, a low negative appendectomy rate can be achieved.

Radioimmunoscintigraphy of gynecologic tumors with 131I-labeled anti-PLAP monoclonal antibodies.

Radioimmunoscintigraphy (RIS) was performed in 20 patients with gynecologic tumors, 14 ovarian, 5 cervical, and one endometrial carcinoma. One murine monoclonal antibody (mab) against placental alkaline phosphatase (H7) was used after radiolabeling with 131I. The labeling procedure yielded antibodies with specific activity varying between 60 and 73 MBq/mg mab. Each patient received 57 to 100 MBq of the preparation. RIS was performed 7 to 35 days later. Patients with ovarian adenocarcinoma had an accumulation of activity on RIS at tumor sites (79%, 11/14) verified by ultrasonography, CT, and clinical examination. A low or absent accumulation of activity was seen in patients with cervical tumors. The patient with an endometrial adenocarcinoma was seen to have an activity accumulation at RIS corresponding to tumor sites determined by ultrasound and/or CT. It is concluded that RIS using monoclonal antibodies against placental alkaline phosphatase can provide information which will supplement that gained from other investigations of patients with ovarian adenocarcinomas.

Inhibition of growth of HeLa cell tumours in nude mice by 125I-labeled anticytokeratin and antiPLAP monoclonal antibodies.

The radiommunotherapeutic potential of 125I-labeled monoclonal antibodies was investigated in 48 nude mice (BALB/c, nu/nu) inoculated s.c. with the HeLa Hep 2 human adenocarcinoma cell line. This isotope, 125I, which is not commonly used for therapeutic purposes caused significant decrease in tumour growth from day 10 to day 42, when coupled to monoclonal antibodies directed against placental alkaline phosphatase (H7) or cytokeratins (TS1). The average growth rate was approximately 50-60% of that observed in the untreated control group after 42 days. The specific radioactivity in each organ 42 days after injection of radiolabeled monoclonal antibodies, indicated that these target antigens retain significant amounts of radiolabeled antibody in the tumours for at least 6 weeks after injection. No weight loss was seen in the animals during this experiment. By use of autoradiographic techniques, the labeled monoclonal antibodies were visualized deep in tumours in characteristic patterns representative of viable tumour cells (H7) and necrotic areas (TS1). The therapeutic approach using 125I labeled antibodies is encouraging and may offer new dimensions in radioimmunotherapy.

Experimental radioimmunotherapy of HeLa tumours in nude mice with 131I-labeled monoclonal antibodies.

The radioimmunotherapeutic potential of 131I-labeled monoclonal antibodies was investigated in 36 nude mice (BALB/c nu/nu) inoculated s.c. with the HeLa Hep 2 human adenocarcinoma cell line. The membrane bound tumour associated antigen placental alkaline phosphatase and several intracellular cytokeratins served as targets for the antibodies. The specific radioactivity in each organ was determined after i.p. injection of the 131I-labeled antibodies (0.2-0.3 mg, approximately 15 MBq/animal), and high localization to the tumours was seen. Significant growth inhibition was observed after injection of the radiolabeled monoclonal antibody H7 against the placental alkaline phosphatase, which reduced the tumour growth to only 12% during a 3 week period compared to a growth of more than 100% for the controls. Animal weight losses were seen. Synthesis of endogenous antibodies to the target antigens was found to be significant. Morphometric evaluation of the relations between stroma, tumour cells and necrotic areas in the tumours after radioimmunotherapy demonstrated a significant increase of the mean relative connective tissue volume and a significant decreased mean of relative volume of tumour cells in the group treated with iodinated antiplacental alkaline phosphatase antibody. This therapeutic principle is encouraging and may offer new possibilities for future treatment of some malignant diseases.

Placental alkaline phosphatase (PLAP)/PLAP-like alkaline phosphatase as tumour marker in relation to CA 125 and TPA for ovarian epithelial tumours.

The significance of the PLAP (Placental alkaline phosphatase)/PLAP-like isozyme as tumour marker in relation to CA 125 and TPA for the monitoring of patients with malignant ovarian epithelial tumours was evaluated. Of all patients (n = 85), 40% had all three markers elevated. CA 125 being the most sensitive (60%), and the PLAP/PLAP-like isozyme and TPA both 40%. A tendency to certain tumour marker patterns of these three antigens in serum can be seen with regard to histopathology. Serous and anaplastic adenocarcinomas usually have all three markers moderately elevated, mucinous and mesonephric adenocarcinomas both have low incidences and low average levels of all three markers. Endometrioid and non-mucinous adenocarcinomas are often associated with high levels of the PLAP/PLAP-like isozyme and CA 125, while TPA shows moderate elevation. The PLAP/PLAP-like isozyme is positively correlated to tumour burden and the outcome of the disease. It may provide additional information on CA 125 in the monitoring of patients with ovarian cancer.

Tumour radioimmunolocalization in nude mice by use of antiplacental alkaline phosphatase monoclonal antibodies.

Three monoclonal antibodies and their Fab and Fab'2 fragments with specificity against human placental alkaline phosphatase (PLAP) were evaluated for tumour immunolocalization of human PLAP-producing Hela Hep 2 tumours in nude mice. The antibodies and their fragments were labelled with 125I and injected intraperitoneally in mice with developing Hep 2 tumours. The animals were followed individually for 14 days with repetitive computerized gamma-camera recordings, which enable quantitation of several crucial parameters, i.e. the time-dependent antibody uptake in the tumours, decrease in background activity and tumour/background ratio. Excellent radioimmunolocalization was obtained with both the intact PLAP-specific immunoglobulins and their fragments but not with the nonspecific antibodies. No background subtraction had to be used. As much as 15% of the initially injected dose could be visualized in the tumours and for the uncleaved mab up to 80% of the radioactivity in the animals was retained in the tumours after 14 days, a considerably longer observation time than usually reported in such tumour xenograft models. The Fab and Fab'2 fragments were found to be excreted fast with less than 5% of the injected dose remaining in the animals after 48 h, but still with positive specific localization to the tumours after an initial high uptake in the kidneys. The results are encouraging and indicate significant potentials of the PLAP-antiPLAP mab system for immunolocalization studies in patients.