Time-of-flight scatter rejection in x-ray radiography

Objective.Time-of-flight (TOF) scatter rejection allows for identifying and discarding scattered photons without the use of an anti-scatter grid (ASG). Although TOF scatter rejection was initially presented for cone-beam computed tomography, we propose, herein, to extend this approach to x-ray radiography. This work aims to evaluate with simulations if TOF scatter rejection can outperform ASGs for radiography.Approach.GATE was used to simulate the radiography of a head and a torso and a water cylinder with bone inserts in a system with total timing jitters from 0 ps up to 500 ps full-width-at-half-maximum. The transmission factor of TOF scatter rejection for primary and scattered photons was evaluated as if it were a virtual ASG.Main results.With a total timing jitter of 50 ps, TOF scatter rejection can reach a selectivity of 4.93 with a primary photons transmission of 99%. Reducing the timing jitter close to 0 ps increases the selectivity up to 15.85 for a head and torso radiography, outperforming typical ASGs which usually have a selectivity from 2.5 to 10 with a primary photons transmission from 50% to 70%.Significance.This suggests that TOF scatter rejection may be suitable to replace ASGs in applications requiring lower radiation exposure if sufficiently low timing jitter is achieved.

Advances in stem cell and other therapies for Huntington's disease: An update

Huntington's disease (HD) is a neurodegenerative disorder caused by an autosomal dominant mutation leading to an abnormal CAG repeat expansion. The result is the synthesis of a toxic misfolded protein, called the mutant huntingtin protein (mHTT). Most current treatments are palliative, but the latest research has expanded into multiple modalities, including stem cells, gene therapy, and even the use of 3D cell structures, called organoids. Stem cell research as a treatment for HD has included the use of various types of stem cells, such as mesenchymal stem cells, neural stem cells, embryonic stem cells, and even reprogrammed stem cells called induced pluripotent stem cells. The goal has been to develop stem cell transplant grafts that will replace the existing mutated neurons, as well as release existing trophic factors for neuronal support. Additionally, research in gene modification using CRISPR-Cas9, PRIME editing, and other forms of genetic modifications are continuing to evolve. Most recently, advancements in stem cell modeling have yielded 3D stem cell tissue models, called organoids. These organoids offer the unique opportunity to transplant a structured stem cell graft which, ideally, models normal human brain tissue more accurately. This manuscript summarizes the recent research in stem cells, genetic modifications, and organoids as a potential for treatment of HD.

The association of Greig syndrome and mastocytosis reveals the involvement of the hedgehog pathway in advanced mastocytosis

Mastocytosis is a heterogeneous disease characterized by an abnormal accumulation of mast cells (MCs) in 1 or several organs. Although a somatic KIT D816V mutation is detected in ∼85% of patients, attempts to demonstrate its oncogenic effect alone have repeatedly failed, suggesting that additional pathways are involved in MC transformation. From 3 children presenting with both Greig cephalopolysyndactyly syndrome (GCPS, Mendelian Inheritance in Man [175700]) and congenital mastocytosis, we demonstrated the involvement of the hedgehog (Hh) pathway in mastocytosis. GCPS is an extremely rare syndrome resulting from haploinsufficiency of GLI3, the major repressor of Hh family members. From these familial cases of mastocytosis, we demonstrate that the Hh pathway is barely active in normal primary MCs and is overactive in neoplastic MCs. GLI3 and KIT mutations had a synergistic, tumorigenic effect on the onset of mastocytosis in a GCPS mouse model. Finally, Hh inhibitors suppressed neoplastic MC proliferation in vitro and extend the survival time of mice with aggressive systemic mastocytosis (ASM). This work revealed, for the first time, the involvement of Hh signaling in the pathophysiology of mastocytosis and demonstrated the cooperative effects of the KIT and Hh oncogenic pathways in mice with ASM, leading to the identification of new promising therapeutic targets.

Further characterization of clinical and laboratory features occurring in VEXAS syndrome in a large-scale analysis of multicenter case-series of 116 French patients

BACKGROUND

A new autoinflammatory syndrome related to somatic mutations of UBA1 was recently described and called VEXAS syndrome.

OBJECTIVE

To describe clinical characteristics, laboratory findings and outcomes of VEXAS syndrome.

DESIGN

Case-series.

SETTING

Patients referred to a French multicenter registry between November 2020 and May 2021.

PATIENTS

116 patients with VEXAS syndrome.

MEASUREMENTS

Frequency and median of parameters and vital status, from diagnosis to the end of the follow-up.

RESULTS

Main clinical features were skin lesions (83.5%), non-infectious fever (63.6%), weight loss (62%), lung involvement (49.6%), ocular symptoms (38.8%), relapsing chondritis (36.4%), venous thrombosis (34.7%), lymph nodes (33.9%), and arthralgia (27.3%). Hematological disease was present in 58 cases (50%), considered as myelodysplastic syndrome (MDS, n= 58) and monoclonal gammapathy of unknown significance (n=12).UBA1 mutations included p.M41T (44.8%), p.M41V (30.2%), p.M41L (18.1%), and splice mutations (6.9%). After a median follow-up of 3.0 years, 18 patients died (15.5%), from infectious origin (n=9) and MDS progression (n=3). Unsupervised analysis identified 3 clusters: cluster 1 (47%) with mild-to-moderate disease; cluster 2 (16%) with underlying MDS and higher mortality rates; cluster 3 (37%) with constitutional manifestations, higher C-reactive protein levels and less frequent chondritis. Five-year probability of survival was 84.2% in cluster 1, 50.5 % in cluster 2, and 89.6% in cluster 3. UBA1 p.Met41Leu mutation was associated with a better prognosis.

CONCLUSION

VEXAS syndrome displays a large spectrum of organ manifestations and shows different clinical and prognostic profiles. It also raises a potential impact of the identified UBA1 mutation.

Effects of azacitidine in 93 patients with IDH1/2 mutated acute myeloid leukemia/myelodysplastic syndromes: a French retrospective multicenter study

Isocitrate dehydrogenase 1 (IDH1) and 2 (IDH2) mutations in Myeloid Neoplams (MNs) exhibit DNA hypermethylation via 2-hydroxyglutarate (2HG) over-production. Clinical impact of azacitidine (AZA) remains inconsistent in IDH1/2-mutated MNs and the potential of serum 2HG as a suitable marker of response to AZA is unknown. To address these questions, we retrospectively analyzed 93 MNs patients (78 AML, 11 MDS, 4 CMML) with IDH1/2 mutations treated with AZA. After a median of 5 cycles of AZA, overall response rate was 28% (including 15% complete remission) and median OS was 12.3 months (significantly shorter in AML compared to MDS/CMML patients). In multivariate analysis of AML patients, DNMT3A mutation was associated with shorter OS while IDH1/2 mutation subtypes had no independent impact. No difference was observed in serum 2HG levels upon AZA treatment between responding and refractory patients suggesting that serum 2HG cannot be used as a surrogate marker of AZA response.

AB0161 CLONAL HEMATOPOIESIS IS INCREASED AND NOT RELATED TO AGING IN SYSTEMIC SCLEROSIS

Background:

Systemic sclerosis (SSc) is an autoimmune disease characterized by fibrosis, microangiopathy and immune dysfunctions including dysregulation of proinflammatory cytokines. Clonal hematopoiesis of indeterminate potential (CHIP) is defined by the acquisition of somatic mutations in hematopoietic stem cells leading to detectable clones in the blood. Recent data have shown a higher risk of cardiovascular disease in patients with CHIP resulting from increased production of proinflammatory cytokines and accelerated atherosclerosis. Eventual links between CHIP and autoimmune diseases are undetermined.

Objectives:

The aim of our study was to evaluate the prevalence of CHIP in SSc patients and its association with clinical phenotype.

Methods:

Forty-one genes frequently mutated in myeloid malignancies were sequenced in peripheral blood mononuclear cells from 90 SSc patients and from 44 healthy donors.

Results:

A total of 15 somatic variants was detected in 13/90 SSc patients (14%) and 4 somatic variants in 4/44 (9%) HD (p=0.58). The prevalence of CHIP was significantly higher in younger SSc patients than in HD: 25% (6/24) vs 4% (1/26) (p=0.045) under 50 years and 17% (7/42) vs 3% (1/38) (p=0.065) under 60 years. The prevalence of CHIP in patients over 70 years was similar in SSc patients and healthy donors

For SSc patients the most common mutations occurred inDNMT3A(7 variants). Other variants involvedATM,SF3B1, SETBP1, TET2,TP53,NF1orCBL. The distribution of gene mutations was overall comparable in SSc patients and in previously described CHIP series (3)

In most SSc patients, we identified a single CHIP mutation. Several mutations were detected in two SSc patients:SETBP1andNF1in one and,TET2andATMin the other Clonal mutations included missense (n=10), nonsense (n=3), frameshift (n=1) and a single splice site mutation. In all HD we detected a single CHIP mutation which occurred inDNMT3A, TP53 and CSF3R

Variant allele frequencies (VAF) of CHIP mutations ranged from 2 to 18.6% and did not differ between genes (DNMT3Aor others). Mean age was the same in patients withDNMT3Amutations or with other mutations. However, C>T transversions, that have been associated with ageing were more frequent inDNMT3Avariants than in other genes, suggesting distinct mechanisms for mutation acquisition or clonal selection No major differences in clinical and laboratory data were observed between SSc patients with or without CHIP. SSc subtypes, disease duration, different organ involvements and the prevalence of ischemic events were not associated with the presence of CHIP, except less frequent pyrosis in patients with CHIP than those without. SSc patients with CHIP had significantly more anti-RNA polymerase III antibodies than those without CHIP (p=0.045) At the time of analysis, 45 SSc patients had received a treatment for SSc which consisted in low-dose steroids, hydroxychloroquine, mycophenolate mofetil, cyclophosphamide or methotrexate. SSc patients with CHIP were significantly more exposed to cyclophosphamide (3/13 vs. 3/77) (p=0.04) (5, 6.5 and 11 gram respectively between 5 years to 8 years before the NGS sequencing analysis), but among these cyclophosphamide-exposed SSc the age was over 65 in 2/3 of them. When considering all immunosuppressive drugs (cyclophosphamide, methotrexate and mycophenolate mofetil) SSc patients with CHIP were not more exposed than those without CHIP (p=0.75) No patient developed any hematologic malignancy and no cytopenia during the median follow-up of 13 months (0-24 months). One SSc patients with CHIP developed a small lung cancer few months after NGS testing.

Conclusion:

Whether CHIP increases the risk to develop SSc or is a consequence of a SSc-derived modified bone marrow micro-environment remains to be explored.

Acknowledgments:

na

Disclosure of Interests:

None declared

Critical Influence of Dielectric Sensitive Material and Manufactured Process in Microwave Gas-Sensing: Application of Ammonia Detection with an Interdigital Sensor

In this paper, authors propose a study on microwave gas sensors and the influence of critical key parameters such as the sensitive material and the circuit conception process. This work aims to determine the influence of these parameters on the quality of the final response of the microwave gas sensor. The fixed geometry of the sensor is a microstrip interdigital capacitor coated with a sensitive layer excited with two 50 Ω SMA ports. The sensitive material has been chosen in order to interact with the target gas: ammonia. Indeed, this gas interacts with phthalocyanine and metal oxides like hematite, TiO₂. To explore the effect of the circuit manufacturing process, three series of samples are prepared. The first series of sensors is produced by classical UV photolithography (process) in the laboratory. The second series of sensors is produced by a subcontractor specialized in rf circuits. The third series is obtained by the experimental platform of the FEMTO-ST laboratory with EVG620 Automated Mask Alignment System Nanoimprint lithography in a clean room. To examine the reliability of this gas sensor at room temperature, it was exposed to different ammonia gas concentrations from 100 to 500 ppm in an argon flow to eliminate coadsorption phenomena. According to the recorded frequency responses, the reflection and transmission coefficients show a change of resonance amplitude due to electrical characteristic modification. This can be correlated to the presence of gaseous ammonia. The chemical nature of the sensitive material layer has a major influence at the excited frequency range. The process of conception influences the sensor sensitivity. The analysis of the results shows a strong correlation between the injected ammonia concentration and its frequency response. The influence of the critical key parameters cited is discussed here.

Time-of-flight computed tomography - proof of principle

Computed tomography has greatly improved over the last decade, especially through x-ray dose exposure reduction while maintaining image quality. Herein, a new concept is proposed to improve the contrast-to-noise ratio (CNR) by including the time-of-flight (TOF) information of individual photons to obtain further insight on the photon's trajectory and to reject scatter contribution. The proof of the concept relies on both simulation and experimental measurements in a cone-beam computed tomography arrangement. Results show a statistical difference between the TOF of scattered and primary photons exploitable in TOF computed tomography. For a large volume of the size of a human abdomen, a scatter reduction from 296% to 4% is achieved in our simulation setup with perfect timing measurements which yields a 110% better CNR, or a dose reduction by a factor of four. Cup artifacts are also reduced from 24.7% to 0.8%, and attenuation inaccuracies are improved from -26.3% to -0.8%. With 100 ps and 10 ps FWHM timing jitters, respectively 75% and 95% of the scatter contribution can be removed with marginal gains below 10 ps. Experimental measurements confirm the feasibility of measuring statistical differences between the TOF of scattered and primary photons.

Transplantation of mesenchymal stem cells genetically engineered to overexpress interleukin-10 promotes alternative inflammatory response in rat model of traumatic brain injury

Background

Traumatic brain injury (TBI) is a major cause for long-term disability, yet the treatments available that improve outcomes after TBI limited. Neuroinflammatory responses are key contributors to determining patient outcomes after TBI. Transplantation of mesenchymal stem cells (MSCs), which release trophic and pro-repair cytokines, represents an effective strategy to reduce inflammation after TBI. One such pro-repair cytokine is interleukin-10 (IL-10), which reduces pro-inflammatory markers and trigger alternative inflammatory markers, such as CD163. In this study, we tested the therapeutic effects of MSCs that were engineered to overexpress IL-10 when transplanted into rats following TBI in the medial frontal cortex.

Methods

Thirty-six hours following TBI, rats were transplanted with MSCs and then assessed for 3 weeks on a battery of behavioral tests that measured motor and cognitive abilities. Histological evaluation was then done to measure the activation of the inflammatory response. Additionally, immunomodulatory effects were evaluated by immunohistochemistry and Western blot analyses.

Results

A significant improvement in fine motor function was observed in rats that received transplants of MSCs engineered to overexpress IL-10 (MSCs + IL-10) or MSCs alone compared to TBI + vehicle-treated rats. Although tissue spared was unchanged, anti-inflammatory effects were revealed by a reduction in the number of glial fibrillary acidic protein cells and CD86 cells in both TBI + MSCs + IL-10 and TBI + MSC groups compared to TBI + vehicle rats. Microglial activation was significantly increased in the TBI + MSC group when compared to the sham + vehicle group. Western blot data suggested a reduction in tumor necrosis factor-alpha in the TBI + MSCs + IL-10 group compared to TBI + MSC group. Immunomodulatory effects were demonstrated by a shift from classical inflammation expression (CD86) to an alternative inflammation state (CD163) in both treatments with MSCs and MSCs + IL-10. Furthermore, co-labeling of both CD86 and CD163 was detected in the same cells, suggesting a temporal change in macrophage expression.

Conclusions

Overall, our findings suggest that transplantation of MSCs that were engineered to overexpress IL-10 can improve functional outcomes by providing a beneficial perilesion environment. This improvement may be explained by the shifting of macrophage expression to a more pro-repair state, thereby providing a possible new therapy for treating TBI.

Bone-marrow-derived mesenchymal stem cells attenuate cognitive deficits in an endothelin-1 rat model of stroke

PURPOSE

Stroke is the third leading cause of death and permanent disability in the United States, often producing long-term cognitive impairments, which are not easily recapitulated in animal models. The goals of this study were to assess whether: (1) the endothelin-1 (ET-1) model of chronic stroke produced discernable cognitive deficits; (2) a spatial operant reversal task (SORT) would accurately measure memory deficits in this model; and (3) bone-marrow-derived mesenchymal stem cells (BMMSCs) could reduce any observed deficits.

METHODS

Rats were given unilateral intracerebral injections of vehicle or ET-1, a stroke-inducing agent, near the middle cerebral artery. Seven days later, they were given intrastriatal injections of BMMSCs or vehicle, near the ischemic penumbra. The cognitive abilities of the rats were assessed on a novel SORT, which was designed to efficiently distinguish cognitive deficits from potential motoric confounds.

RESULTS

Rats given ET-1 had significantly more cognitive errors at six weeks post-stroke on the SORT, and that these deficits were attenuated by BMMSC transplants.

CONCLUSIONS

These findings indicate that: (1) the ET-1 model produces chronic cognitive deficits; (2) the SORT efficiently measures cognitive deficits that are not confounded by motoric impairment; and (3) BMMSCs may be a viable treatment for stroke-induced cognitive dysfunction.

Radioimmunotherapy ((90) Y-Ibritumomab Tiuxetan) for Posttransplant Lymphoproliferative Disorders After Prior Exposure to Rituximab

Posttransplantation lymphoproliferative disorders (PTLDs) are life-threatening complications after solid organ and hematopoietic stem cell transplantation. Only half of CD20-positive PTLDs respond to rituximab monotherapy, and outcomes remain poor for patients with relapsed/refractory disease, especially those who do not qualify for an anthracycline containing regimen due to frailty or comorbidities. Radioimmunotherapy (RIT) might be an option in this particular setting. We report a panel of eight patients with rituximab refractory/relapsed CD20-positive PTLDs including three ineligible for subsequent CHOP-like chemotherapy who received (90) Y-Ibritumomab tiuxetan as a single agent (n = 7) or combined to chemotherapy (n = 1). Five out of eight patients were kidney transplant recipients, while 2/8 had a liver transplant and 1/8 had a heart transplant. Patients received a median of two previous therapies. Overall response rate was 62.5%. Importantly, all responders achieved complete response. At a median follow-up of 37 months [5; 84], complete response was ongoing in four patients. Toxicity was predominantly hematological and easily manageable. No graft rejection was noticed concomitantly or following RIT administration despite immunosuppression reduction after diagnosis of PTLDs. This report emphasizes the potential efficiency of salvage RIT for early rituximab refractory PTLDs without any unexpected toxicity.

Assessing the potential clinical utility of transplantations of neural and mesenchymal stem cells for treating neurodegenerative diseases

Treatments for neurodegenerative diseases have little impact on the long-term patient health. However, cellular transplants of neuroblasts derived from the aborted embryonic brain tissue in animal models of neurodegenerative disorders and in patients have demonstrated survival and functionality in the brain. However, ethical and functional problems due to the use of this fetal tissue stopped most of the clinical trials. Therefore, new cell sources were needed, and scientists focused on neural (NSCs) and mesenchymal stem cells (MSCs). When transplanted in the brain of animals with Parkinson's or Huntington's disease, NSCs and MSCs were able to induce partial functional recovery by promoting neuroprotection and immunomodulation. MSCs are more readily accessible than NSCs due to sources such as the bone marrow. However, MSCs are not capable of differentiating into neurons in vivo where NSCs are. Thus, transplantation of NSCs and MSCs is interesting for brain regenerative medicine. In this chapter, we detail the methods for NSCs and MSCs isolation as well as the transplantation procedures used to treat rodent models of neurodegenerative damage.

New lines of GFP transgenic rats relevant for regenerative medicine and gene therapy

Adoptive cell transfer studies in regenerative research and identification of genetically modified cells after gene therapy in vivo require unequivocally identifying and tracking the donor cells in the host tissues, ideally over several days or for up to several months. The use of reporter genes allows identifying the transferred cells but unfortunately most are immunogenic to wild-type hosts and thus trigger rejection in few days. The availability of transgenic animals from the same strain that would express either high levels of the transgene to identify the cells or low levels but that would be tolerant to the transgene would allow performing long-term analysis of labelled cells. Herein, using lentiviral vectors we develop two new lines of GFP-expressing transgenic rats displaying different levels and patterns of GFP-expression. The "high-expresser" line (GFP(high)) displayed high expression in most tissues, including adult neurons and neural precursors, mesenchymal stem cells and in all leukocytes subtypes analysed, including myeloid and plasmacytoid dendritic cells, cells that have not or only poorly characterized in previous GFP-transgenic rats. These GFP(high)-transgenic rats could be useful for transplantation and immunological studies using GFP-positive cells/tissue. The "low-expresser" line expressed very low levels of GFP only in the liver and in less than 5% of lymphoid cells. We demonstrate these animals did not develop detectable humoral and cellular immune responses against both transferred GFP-positive splenocytes and lentivirus-mediated GFP gene transfer. Thus, these GFP-transgenic rats represent useful tools for regenerative medicine and gene therapy.

Nitazoxanide, a nitrothiazolide antiparasitic drug, is an anti-Helicobacter pylori agent with anti-vacuolating toxin activity

Nitazoxanide (NTZ), a synthesized drug of the nitrothiazolide class, was initially developed as an antiparasitic compound. This compound has recently been shown to have antibacterial activities against some bacterial pathogens. In the present study, NTZ and its main metabolite tizoxanide (TIZ) were found to have strong minimum inhibitory concentrations (MICs) against both metronidazole (MTZ)-resistant strains and sensitive clinical isolates of Helicobacter pylori. The MIC90 of both NTZ and TIZ against 37 clinical isolates was 8 microg/ml. Vacuolating toxin activity of H. pylori assayed by HeLa cell vacuole formation was inhibited by NTZ at a sub-MIC. In contrast, urease production by H. pylori was not specifically affected by the sub-MIC of NTZ. An acidic pH (pH 5.0) medium reduced the antimicrobial activity of the drug in terms of growth inhibition due to the low growth rate of the bacteria, but killing activity of NTZ against the bacteria was still observed. Thus, it was apparent that both NTZ and TIZ are highly effective against H. pylori, even when the bacteria are resistant to MTZ.

Comments on an experimental end-user training course

The MEDLINE training course organized for users was based on the experience acquired by IMA from problem encountered in the user/system concerning: (a) The understanding of a computerized documentation system and its capabilitiesd. (b) The role of the computer, often over-estimated. (c) The user-search analyst interface, i.e. the role of the analyst, the necessity for the user to explain his question clearly and his real need for information. All these problems were discussed concretely with the help of specific searches presented by each of the participants.