Humanization of T cell-mediated immunity in mice.

Despite the enormous promise of T cell therapies, the isolation and study of human T cell receptors (TCRs) of dedicated specificity remains a major challenge. To overcome this limitation, we generated mice with a genetically humanized system of T cell immunity. We used VelociGene technology to replace the murine TCRαß variable regions, along with regions encoding the extracellular domains of co-receptors CD4 and CD8, and major histocompatibility complex (MHC) class I and II, with corresponding human sequences. The resulting "VelociT" mice have normal myeloid and lymphoid immune cell populations, including thymic and peripheral αß T cell subsets comparable with wild-type mice. VelociT mice expressed a diverse TCR repertoire, mounted functional T cell responses to lymphocytic choriomeningitis virus infection, and could develop experimental autoimmune encephalomyelitis. Immunization of VelociT mice with human tumor-associated peptide antigens generated robust, antigen-specific responses and led to identification of a TCR against tumor antigen New York esophageal squamous cell carcinoma-1 with potent antitumor activity. These studies demonstrate that VelociT mice mount clinically relevant T cell responses to both MHC-I­ and MHC-II­restricted antigens, providing a powerful new model for analyzing T cell function in human disease. Moreover, VelociT mice are a new platform for de novo discovery of therapeutic human TCRs.

Evaluating the use of gradient echo imaging for the detection of cerebral microbleeds in acute stroke cases: A retrospective data analysis in a UK stroke unit.

INTRODUCTION: Imaging in stroke, allows its classification into ischaemic stroke (IS) or intracranial haemorrhagic stroke (ICH), ensuring time-sensitive treatment to be administered. Imaging can also allow detection of cerebral microbleeds (CMBs), which may further determine pharmacological intervention in acute stroke. True gradient echo (T2∗GRE) or susceptibility weighted imaging (SWI) have high sensitivity for the detection of CMBs. These two sequences are included in the national guidelines; however, the implementation of these guidelines can vary depending on local interpretation and scanner capabilities. AIM: To explore the use and application of blood sensitive MRI sequences in a specialist UK stroke unit for the detection of CMBs, to improve local practice. METHODS: A retrospective data analysis of the native database, spanning a 6-month period, was used. The data of 281 acute stroke patients with an MRI were reviewed and analysed. The MRI sequences applied, and the final diagnosis were noted for each case. RESULTS: Of the 281 acute stroke patients with MRI, 259 (92.1%) had an IS, 16 (5.68%) an ICH and 6 (2.14%) had both. Overall, 13 (4.63%) had a CMB diagnosis. All of these 13 patients had a true T2∗GRE sequence. CMBs were not detected in the absence of a T2∗GRE sequence. CONCLUSION: T2∗GRE imaging is essential for detecting CMBs. When omitted, CMB incidence can be considerably lower than that suggested in the literature. Missing CMB diagnoses in stroke patients may result in suboptimal treatment pathways, compromising the patients' standard of care. IMPLICATIONS FOR PRACTICE: When SWI is not available, it is imperative to always include a true T2∗GRE sequence to detect microbleeds in suspected acute stroke cases.

Quantification and characterization of granulocyte macrophage colony-stimulating factor activated human peripheral blood mononuclear cells by fluorine-19 cellular MRI in an immunocompromised mouse model.

PURPOSE: The purpose of this study was to test fluorine-19 (19F) cellular magnetic resonance (MRI) as a non-invasive imaging modality to track therapeutic cell migration as a surrogate marker of immunotherapeutic effectiveness. MATERIALS AND METHODS: Human peripheral blood mononuclear cell- (PBMC)-derived antigen presenting cell (APC) were labeled with a 19F-perfluorocarbon (PFC) and/or activated with granulocyte macrophage colony-stimulating factor (GM-CSF). Viability, phenotype and cell lineage characterization preceded 19F cellular MRI of PFC+ PBMC under both pre-clinical 9.4 Tesla (T) and clinical 3T conditions in a mouse model. RESULTS: A high proportion of PBMC incorporated PFC without affecting viability, phenotype or cell lineage composition. PFC+ PBMC were in vivo migration-competent to draining and downstream lymph nodes. GM-CSF addition to culture increased PBMC migration to, and persistence within, secondary lymphoid organs. CONCLUSION: 19F cellular MRI is a non-invasive imaging technique capable of detecting and quantifying in vivo cell migration in conjunction with an established APC-based immunotherapy model. 19F cellular MRI can function as a surrogate marker for assessing and improving upon the therapeutic benefit that this immunotherapy provides.

Incidence of pulmonary embolism after the first 3 months of spinal cord injury.

BACKGROUND: Pulmonary embolism (PE) is a significant cause of morbidity and mortality in patients with spinal cord injury (SCI). Prophylactic anticoagulation is associated with a reduction in mortality rates, but there is limited evidence regarding the incidence rate of PE following cessation of anticoagulation after the first 3 months of injury. STUDY DESIGN: Single-centre retrospective study. OBJECTIVE: To estimate the incidence rate of PE after 90 days of SCI. SETTING: The National Spinal Injuries Centre at Stoke Mandeville Hospital, Aylesbury, UK. METHODS: The study includes 640 new-onset SCI patients. All computer tomography pulmonary angiograms (CTPAs) or ventilation-perfusion lung scans between 2008 and 2013 were identified. Medical notes and scans were reviewed and clinical outcomes and radiological findings were recorded. RESULTS: A total of 91 patients with a new-onset SCI had a CTPA or a perfusion lung scan. PE was detected in a total of 8 patients. The incidence of PE was 1.25%; 95% confidence interval (0.39-2.11) over a 6-year period. The duration of injury at the time of PE was 7 months. CONCLUSION: The incidence rate of PE post 3 months of SCI remains significant, though much lower than immediately post injury.

Humoral Immune Response against Nontargeted Tumor Antigens after Treatment with Sipuleucel-T and Its Association with Improved Clinical Outcome.

PURPOSE: Antitumor activity of cancer immunotherapies may elicit immune responses to nontargeted (secondary) tumor antigens, or antigen spread. We evaluated humoral antigen spread after treatment with sipuleucel-T, an immunotherapy for asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC), designed to target prostatic acid phosphatase (PAP; primary antigen). EXPERIMENTAL DESIGN: Serum samples from patients with mCRPC enrolled in the placebo-controlled phase III IMPACT study (evaluable n = 142) were used to assess humoral antigen spread after treatment with sipuleucel-T. Immunoglobulin G (IgG) responses to self-antigens (including tumor antigens) were surveyed using protein microarrays and confirmed using Luminex xMAP. IgG responses were subsequently validated in ProACT (n = 33), an independent phase II study of sipuleucel-T. Association of IgG responses with overall survival (OS) was assessed using multivariate Cox models adjusted for baseline prostate-specific antigen (PSA) and lactate dehydrogenase levels. RESULTS: In patients from IMPACT and ProACT, levels of IgG against multiple secondary antigens, including PSA, KLK2/hK2, K-Ras, E-Ras, LGALS8/PCTA-1/galectin-8, and LGALS3/galectin-3, were elevated after treatment with sipuleucel-T (P < 0.01), but not control. IgG responses (≥ 2-fold elevation posttreatment) occurred in ≥ 25% of patients, appeared by 2 weeks after sipuleucel-T treatment, and persisted for up to 6 months. IgG responses to PSA and LGALS3 were associated with improved OS in sipuleucel-T-treated patients from IMPACT (P ≤ 0.05). CONCLUSIONS: Sipuleucel-T induced humoral antigen spread in patients with mCRPC. IgG responses were associated with improved OS in IMPACT. The methods and results reported may identify pharmacodynamic biomarkers of clinical outcome after sipuleucel-T treatment, and help in clinical assessments of other cancer immunotherapies. See related commentary by Hellstrom and Hellstrom, p. 3581.

Posterior circulation infarction in patients with traumatic cervical spinal cord injury and its relationship to vertebral artery injury.

STUDY DESIGN: Prospective study. OBJECTIVE: To ascertain the prevalence of posterior circulation stroke in traumatic chronic spinal cord injured (SCI) patients and associated traumatic vertebral artery injuries (VAI). METHODS: All adult patients with cervical SCI and American Spinal Injury Association Impairment Scale (AIS) grade A or B referred for follow-up magnetic resonance imaging of their spinal cord were invited to take part in the study between January 2010 and December 2012 at the National Spinal Injury Centre. Two additional sequences were added to the existing imaging protocol to evaluate the brain and vertebral arteries. RESULTS: Ninety-eight patients were recruited. All imaging were analysed independently by three consultant radiologists. Posterior circulation infarcts were noted in seven (7%) patients. Significant VAI was noted in 13 patients (13%) with 10 occlusions and 3 with high-grade stenosis. However, only one patient had co-existent posterior circulation infarct and significant VAI. CONCLUSION: There is an increased prevalence of posterior circulation infarction in SCI patients. The relationship with associated traumatic VAI requires further investigation.

Outcomes of whole-body computed tomography in spinal cord-injured patients with sepsis.

STUDY DESIGN: Retrospective case series. OBJECTIVES: To evaluate the efficacy of body computed tomography (CT) in spinal cord injury (SCI) patients with sepsis. SETTING: Specialist acute care and rehabilitation SCI centre in United Kingdom. METHODS: Patients with SCI and suspected or known sepsis, who had CT of the chest, abdomen and pelvis, over a 4-year period, were identified. Only patients who fulfilled the definition of sepsis or severe sepsis were included. Their medical notes and CT scans were reviewed and clinical outcomes and radiological findings recorded. RESULTS: Twenty-two patients with sepsis were identified including seven categorised as having severe sepsis. A specific radiological diagnosis was found in three patients (14%) and non-specific findings were found in 15 patients (68%). CONCLUSION: Although in the majority of cases, the findings were non-specific, a small number of patients had significant pathology identified by CT, which influenced their management significantly.

Applications of systems biology in cancer immunotherapy: from target discovery to biomarkers of clinical outcome.

Immunotherapies are coming to the forefront as a treatment paradigm in cancer with multiple US FDA approvals in recent years and a better understanding of their therapeutic mode of action. The control of tumor growth by the immune system is orchestrated by a complex array of cellular interactions and molecular pathways, both in the immune cells as well as the tumor. Although research over the past three decades has elucidated many aspects of tumor immunosurveillance, given the inherent complexity of the immune cell phenotypes and function, high-throughput molecular profiling ('omics') approaches have now become essential to support the discovery and development of new therapies. Technologies, such as DNA and protein microarrays, deep sequencing, mass spectrometry, as well as the computational methods for their analyses, are advancing the contributions of systems biology towards the development and mechanistic understanding of cancer immunotherapies. In this review, the authors illustrate this through some recently reported studies.

Out-of-hours MRI provision in the UK and models of service delivery.

AIM: To examine current out-of-hours magnetic resonance imaging (MRI) provision through a snapshot survey of National Health Service (NHS) trusts and to assay how radiographer staffing cover was provided for out-of-hours services. MATERIALS AND METHODS: A snapshot postal survey was mailed to heads of service of all 234 trusts in England and Wales. A literature search on the models of service delivery and correlation with the authors' internal MRI rota, which has provided a full on-call service for 20 years was undertaken. RESULTS: The response rate was 45.7% (107 of 234); 14% of responders provided full access to MRI 24 h a day; 63% provided extended weekday service, typically to 20.00 h; and 81% provided a weekend daytime service. The radiographers running the service were typically from the core MRI team. Approximately one-third (29.9%) of trusts provided training in basic brain and spine MRI to non-core MRI team members, but they typically did not participate in out-of-hours provision. CONCLUSION: There is currently a paucity of information on the provision of out-of-hours MRI in the NHS. However, there is increasing pressure to provide complex imaging out of hours, and in the future, trauma centres may be required to provide MRI to assess spinal injury. The authors describe a system to provide access to MRI at no additional cost to the organization based on 20 years of experience. A minority of surveyed acute NHS trusts have full out-of-hours access to MRI. Demand for MRI provision out of core hours is likely to increase.

The neural substrates of person perception: spontaneous use of financial and moral status knowledge.

The current study examines the effect of status information on the neural substrates of person perception. In an event-related fMRI experiment, participants were presented with photographs of faces preceded with information denoting either: low or high financial status (e.g., "earns $25,000" or "earns $350,000"), or low or high moral status (e.g., "is a tobacco executive" or "does cancer research"). Participants were asked to form an impression of the targets, but were not instructed to explicitly evaluate their social status. Building on previous brain-imaging investigations, regions of interest analyses were performed for brain regions expected to support either cognitive (i.e., intraparietal sulcus) or emotional (i.e., ventromedial prefrontal cortex) components of social status perception. Activation of the intraparietal sulcus was found to be sensitive to the financial status of individuals while activation of the ventromedial prefrontal cortex was sensitive to the moral status of individuals. The implications of these results towards uncovering the neural substrates of status perception and, more broadly, the extended network of brain regions involved in person perception are discussed.

Long-term effect of MRI on sacral anterior root stimulator: the Stoke Mandeville experience.

STUDY DESIGN: Retrospective review study. OBJECTIVES: To identify whether it is safe to perform a magnetic resonance imaging (MRI) exam on patients who have a sacral anterior root stimulator (SARS). SETTING: Adult patients with spinal cord injury and implanted SARS attending the National Spinal Injuries Centre who have had MRI scans. METHODS: Retrospective review between 1989 and 2010. The effect of the MRI scans on the function of the SARS (Finetech-Brindley, UK) was assessed up to 6 months following MRI at 0.2 and 1.5 T. RESULTS: A total of 18 patients with SARS implants had MRI scans at 0.2 and 1.5 T of the cervical, thoracic and lumbar spine, head, shoulder and pelvis. MRI examinations were abandoned on two occasions in one patient due to radiofrequency interference. One patient's stimulator ceased to function 5 months following MRI; both of these patients showing complications had their MRI examinations at 0.2 T. There were no adverse effects at 1.5 T. In one patient the SARS was removed within 6 months after MRI due to an unrelated medical condition. A total of 17 patients showed no symptoms that required terminating the examination. In all the 11 patients with a complete and functioning implant before MRI at 1.5 T, the SARS was functioning appropriately, and no change in bladder function was reported up to 6 months following MRI. CONCLUSION: It is safe to perform an MRI scan on patients with SARS providing the examination is conducted in a 1.5 T system.

MRI in acute and subacute post-traumatic spinal cord injury: pictorial review.

STUDY DESIGN: Pictorial review. OBJECTIVES: To illustrate MRI signs of acute and subacute injury with emphasis on evidence-based links to clinical outcome and implications for treatment. METHODS: Description of important aspects of MRI techniques and illustration of critical MRI signs important in the assessment of spinal cord injury following trauma, in the acute and subacute stages. CONCLUSIONS: Familiarity with cord MRI appearances has an important impact on planning the management of the acutely spinal cord injured patient and also identifying complications in the subacute phase particularly in the presence of neurological deterioration.

Resolution of SPAM following cordectomy: implications for understanding pathophysiology.

STUDY DESIGN: Case report. OBJECTIVE: To describe the clinical benefit of a spinal cordectomy with the aim of limiting neurological deterioration related to the development of a subacute posttraumatic ascending myelopathy (SPAM) supporting previously described mechanism for SPAM formation. SETTING: National Spinal Injuries Centre, Stoke Mandeville Hospital, UK. METHOD AND RESULTS: A 38-year old patient presented 6 months after spinal cord injury substantial neurological deterioration expanding from the initial T4-injury level through C4. Magnetic resonance imaging revealed intra-medullary haemorrhage at the site of injury and subsequent-ascending cord oedema. A cordectomy was performed leading to neurological stabilisation and complete resolution of SPAM. CONCLUSION: Cordectomy can be an effective intervention in case of rapid progressive neurological deterioration.

Comparison of computed tomographic and magnetic resonance imaging in fracture healing after spinal injury.

STUDY DESIGN: Single-centre, prospective (comparative cohort) clinical study, with ethical approval and patient consent. OBJECTIVE: Confirmation of vertebral fracture union can pose significant challenges for clinicians in the management of spinal cord injury and in the decisions around patient mobilization. Bony union is usually assessed with computed tomography (CT). This study hypothesizes that magnetic resonance imaging (MRI) can identify vertebral bone union. SETTING: A major spinal injuries unit in the United Kingdom. METHOD: Patients underwent CT and MRI at 12 weeks post-injury, if conservatively managed, or 12 weeks post-fixation. With CT as the gold standard, the MRI scans were reviewed blind to the CT result and indicators for fracture healing were compared. RESULTS: A total of 35 patients with 55 fractures were imaged. Comparison of CT and MRI showed sensitivity of 88%, specificity of 100% and positive predictive value of 100% for fracture union imaged with MRI using CT as the gold standard. CONCLUSION: MRI correlates well with CT in identifying vertebral fracture union and non-union. We suggest that where imaging is indicated in the assessment of vertebral body fracture healing MRI can be used routinely with CT reserved for problematic or inconclusive cases.

Differential diagnosis of restricted diffusion confined to the cerebral cortex.

Diffusion-weighted MRI (DWI) has become increasingly widely available over recent years and is recognized as a powerful tool in neuroimaging. It is primarily used to identify acute ischaemia in patients presenting with stroke because of the improved sensitivity it offers early in the course of the disease. DWI also contributes useful diagnostic information in a range of other conditions. In this review we describe the magnetic resonance imaging (MRI) features of a number of conditions characterized by cortical diffusion restriction (CDR).

Subacute progressive ascending myelopathy following spinal cord injury: MRI appearances and clinical presentation.

STUDY DESIGN: Retrospective Case Review. OBJECTIVES: To describe the clinical presentation and course of patients with magnetic resonance imaging (MRI) features of subacute progressive ascending myelopathy (SPAM). A rare complication of spinal cord injury. SETTING: National Spinal Injuries Centre, Stoke Mandeville Hospital, UK. MATERIALS AND METHODS: A retrospective review of the case notes and MRI studies of 11 cases with typical MRI features of ascending myelopathy presenting to a tertiary Spinal Injuries centre over a 15-year period. RESULTS: Eleven patients were identified with MRI features typical of SPAM, a median of 13 days (mean 24, range 4-86 days) following cord injury. The median number of cord segments involved above the initial insult was 6 (mean 6.2, range 4-11). MRI appearances include extension four or more segments cephalad to the initial cord injured segment, cord expansion and increased intramedullary T2 signal with a rim of cord sparing peripherally. Cord changes and neurological deficits improved over time but did not return to the initial injured level on MRI. One patient died (mortality 9%). CONCLUSION: SPAM is a rare cause of neurological deterioration following spinal cord injury but may remain subclinical. SPAM most commonly presents as neurological deterioration but may present with shoulder pain, respiratory deterioration or remain subclinical. There are characteristic MRI appearances. It can be fatal.

Presence of acute ischaemic lesions on diffusion-weighted imaging is associated with clinical predictors of early risk of stroke after transient ischaemic attack.

BACKGROUND: Early risk of stroke after a transient ischaemic attack (TIA) can be reliably predicted with risk scores based on clinical features of the patient and the event, but it is unclear how these features correlate with findings on brain imaging and few studies have investigated this in the subacute phase. METHODS: Two hundred consecutive patients attending a specialist clinic underwent diffusion-weighted brain imaging (DWI) on the day of the clinic (> or =3 days after a TIA) and the presence of recent lesions (positive DWI) was related to the presence of clinical features associated with a high stroke risk and to 2 validated risk scores (ABCD and California). RESULTS: Thirty-one patients (16%) had positive DWI. Increasing ABCD and California scores were associated with positive DWI (p = 0.02 for both) independent of the delay from TIA to scan. CONCLUSION: Presence of recent ischaemic lesions on DWI correlates with validated clinical scores for risk of stroke after TIA in patients scanned subacutely. Future prognostic studies of DWI after TIA should adjust for the risk scores to determine the independent predictive value of DWI and hence the likely role of DWI in refinements of the scores.

Diffusion weighted magnetic resonance imaging for acute stroke: practical and popular.

AIM: To evaluate the feasibility and impact of diffusion weighted magnetic resonance imaging (DW MRI) as the first line neuroimaging of stroke at a district general hospital. METHODS: Prospective audit of all in-patients admitted with clinically suspected acute stroke and referred for imaging over a consecutive 17 week period. The data collected included scan type, time from cerebral event to imaging request, and time from formal radiological request to neuroimaging. Clinicians' (general physicians, neurologists, and radiologists) perceptions were assessed by a questionnaire. RESULTS: 148 patients had neuroimaging for clinically suspected stroke during this period. Eighty one per cent of patients (120 of 148) had DW MRI as first line. Ninety two per cent of these patients had DW MRI within 24 hours of the formal radiological request. Twenty eight patients did not undergo DW MRI because lack of MRI safety, clinical state, unavailability because of maintenance service or lack of trained staff. Clinicians found the introduction of the DW MRI based service a significant improvement on computed tomography, especially for equivocal cases. CONCLUSION: DW based MRI service is both feasible and sustainable in the setting of a district general hospital and most clinicians feel that this is a significant improvement to stroke services.