Deep learning for automatic organ and tumor segmentation in nanomedicine pharmacokinetics.

Rationale: Multimodal imaging provides important pharmacokinetic and dosimetry information during nanomedicine development and optimization. However, accurate quantitation is time-consuming, resource intensive, and requires anatomical expertise. Methods: We present NanoMASK: a 3D U-Net adapted deep learning tool capable of rapid, automatic organ segmentation of multimodal imaging data that can output key clinical dosimetry metrics without manual intervention. This model was trained on 355 manually-contoured PET/CT data volumes of mice injected with a variety of nanomaterials and imaged over 48 hours. Results: NanoMASK produced 3-dimensional contours of the heart, lungs, liver, spleen, kidneys, and tumor with high volumetric accuracy (pan-organ average %DSC of 92.5). Pharmacokinetic metrics including %ID/cc, %ID, and SUVmax achieved correlation coefficients exceeding R = 0.987 and relative mean errors below 0.2%. NanoMASK was applied to novel datasets of lipid nanoparticles and antibody-drug conjugates with a minimal drop in accuracy, illustrating its generalizability to different classes of nanomedicines. Furthermore, 20 additional auto-segmentation models were developed using training data subsets based on image modality, experimental imaging timepoint, and tumor status. These were used to explore the fundamental biases and dependencies of auto-segmentation models built on a 3D U-Net architecture, revealing significant differential impacts on organ segmentation accuracy. Conclusions: NanoMASK is an easy-to-use, adaptable tool for improving accuracy and throughput in imaging-based pharmacokinetic studies of nanomedicine. It has been made publicly available to all readers for automatic segmentation and pharmacokinetic analysis across a diverse array of nanoparticles, expediting agent development.

Preclinical evidence of a direct pro-survival role of arginine deprivation in multiple myeloma.

Multiple myeloma grows by establishing multiple interactions with bone marrow cells. These include expansion of myeloid-derived suppressor cells, which drive immunoevasion via mechanisms that include arginase-1-driven depletion of L-arginine, thus indirectly promoting myeloma cell survival and tumor progression. The peculiar biology of malignant plasma cells postulates that arginine depletion may benefit their fitness also directly, e.g., by engaging the integrated stress response, or by stimulating autophagy through mTORC1 inhibition. We thus investigated the direct impact of arginine deprivation on myeloma cells and challenged its pathophysiological relevance in vitro and in vivo. First, we found that partial arginine depletion spared proliferation of human multiple myeloma cells at concentrations that arrest human T cells. Next, we asked if arginine shortage activates putative adaptive pathways in myeloma cells. Low arginine failed to activate the integrated stress response, as indicated by unmodified phosphorylation of the eukaryotic initiation factor 2α, but sizably inhibited mTORC1, as revealed by reduced phosphorylation of ribosomal protein S6. Notably, depressed mTORC1 activity was not sufficient to increase autophagy, as assessed by the lysosomal digestion rate of the autophagosome-associated protein, LC3-II. Rather, it stimulated mTORC2, resulting in increased phosphatidylinositol-3 kinase-dependent AKT phosphorylation and activity, leading to heightened inhibitory phosphorylation of the pro-apoptotic BAD protein. We then tested whether arginine depletion-activated AKT may protect malignant plasma cells from cell death. Indeed, culturing myeloma cells in low arginine medium significantly reduced the apoptotic effect of the first-in-class proteasome inhibitor, bortezomib, an outcome prevented by pharmacological inhibition of AKT phosphorylation. Finally, we challenged the relevance of the identified circuit in vivo. To gauge the pathophysiologic relevance of low arginine to myeloma growth independently of immunoevasion, we xenotransplanted human myeloma cells subcutaneously into T cell-deficient Rag2-/-γc-/- recipient mice and treated palpable tumor-bearing mice with the clinical-grade arginase inhibitor CB1158. Arginase inhibition significantly raised serum arginine concentration, reduced tumor growth by caliper assessment, and decreased intra-tumor AKT phosphorylation in vivo. Altogether, our results reveal a novel direct pro-survival effect of arginine deprivation on myeloma cells, with potential therapeutic implications.

Analgesic effects of a capacitive-resistive monopolar radiofrequency in patients with myofascial chronic neck pain: a pilot randomized controlled trial

SUMMARY BACKGROUND: To date, there is a lack of prior studies on the use of capacitive resistive monopolar radiofrequency (RF) to treat neck pain. The objective of this study was to investigate the immediate effect of capacitive resistive monopolar radiofrequency (RF=448 kHz), in comparison with a placebo, on (1) reducing neck pain intensity at myofascial trigger points (MTrP), (2) decreasing neck disability and (3) improving cervical range of motion (CROM). METHODS: A randomized, double-blind, placebo-controlled trial (NCT02353195) was carried out. Patients with myofascial chronic neck pain (N=24) with active MTrP in one upper trapezius muscle were randomly divided into two groups: a radio-frequency group, which received eight sessions of a monopolar capacitive resistive radio-frequency application over the upper trapezius muscle, and a placebo group (PG), which received eight sessions of placebo radio-frequency over the same muscle. Visual analog scale (VAS), CROM and Neck Disability Index (NDI) were evaluated after the first session and after the eight sessions. RESULTS: The Wilcoxon test for VAS showed statistically significant differences between baseline, immediately after the first session and after eight sessions (p<.001). No significant differences for PG were found. No differences were observed between groups. NDI improved in both groups after eight sessions, but no differences were found between groups (p<.05). ANOVA for time factor showed statistically significant changes in the right cervical rotation in both groups (F=4.112; p=.026) after eight sessions. CONCLUSIONS: Even though there were no differences between both groups, the monopolar capacitive, resistive RF could have a potential effect on pain intensity.

RESUMO ANTECEDENTES: Até a data, há uma falta de estudos prévios para tratar a dor no pescoço por radiofrequência (RF) monopolar capacitiva resistiva. O objetivo deste estudo foi investigar o efeito imediato da radiofrequência monopolar capacitiva resistiva (RF = 448 kHz) versus placebo em (1) redução da intensidade da dor no pescoço em pontos de gatilho miofascial (MTrP), (2) diminuição da incapacidade do pescoço e (3) melhorando a amplitude de movimento cervical (Crom). MÉTODOS: Foi realizado um ensaio randomizado, duplo-cego, controlado por placebo (NCT02353195). Os pacientes com dor no pescoço crônica miofascial (N = 24) com MTrP ativo em um músculo trapézio superior foram divididos aleatoriamente em dois grupos: um grupo de radiofrequência, que recebeu oito sessões com uma aplicação de radiofrequência resistiva capacitiva monopolar sobre o músculo trapézio superior, e um grupo de placebo (PG), que recebeu oito sessões de radiofrequência de placebo no mesmo músculo. A escala analógica visual (VAS), Crom e Índice de incapacidade do pescoço (NDI) foram avaliadas após a primeira sessão e após as oito sessões. RESULTADOS: O teste de Wilcoxon para VAS mostrou diferenças estatisticamente significativas entre a linha de base e imediatamente após a primeira sessão e após oito sessões (p < 0,001). Não foram encontradas diferenças significativas para PG. Não foram observadas diferenças entre os grupos. O NDI melhorou em ambos os grupos após oito sessões, mas não foram encontradas diferenças entre os grupos (p < 0,05). A Anova para o fator de tempo mostrou mudanças estatisticamente significativas na rotação direita cervical em ambos os grupos (F = 4,12; p = 0,26) após oito sessões. CONCLUSÕES: Apesar de não haver diferenças entre os dois grupos, o RF resistivo capacitivo monopolar pode ter um efeito potencial sobre a intensidade da dor.

Proteasome stress sensitizes malignant pleural mesothelioma cells to bortezomib-induced apoptosis.

Based on promising results in preclinical models, clinical trials have been performed to evaluate the efficacy of the first-in-class proteasome inhibitor bortezomib towards malignant pleural mesothelioma (MPM), an aggressive cancer arising from the mesothelium of the serous cavities following exposure to asbestos. Unexpectedly, only minimal therapeutic benefits were observed, thus implicating that MPM harbors inherent resistance mechanisms. Identifying the molecular bases of this primary resistance is crucial to develop novel pharmacologic strategies aimed at increasing the vulnerability of MPM to bortezomib. Therefore, we assessed a panel of four human MPM lines with different sensitivity to bortezomib, for functional proteasome activity and levels of free and polymerized ubiquitin. We found that highly sensitive MPM lines display lower proteasome activity than more bortezomib-resistant clones, suggesting that reduced proteasomal capacity might contribute to the intrinsic susceptibility of mesothelioma cells to proteasome inhibitors-induced apoptosis. Moreover, MPM equipped with fewer active proteasomes accumulated polyubiquitinated proteins, at the expense of free ubiquitin, a condition known as proteasome stress, which lowers the cellular apoptotic threshold and sensitizes mesothelioma cells to bortezomib-induced toxicity as shown herein. Taken together, our data suggest that an unfavorable load-versus-capacity balance represents a critical determinant of primary apoptotic sensitivity to bortezomib in MPM.

Hybrid metal/scaffold-jacket versus full-metal jackets in left anterior descending coronary artery diffuse disease: Differences in radiation exposure and fluoroscopic/procedural times.

BACKGROUND/PURPOSE: Bioabsorbable vascular scaffolds (BVS) are made from a radiolucent material. Their multiple implantations on a single long diffused segment requires a specific technique with imaging magnification, which could cause an increase in dose delivered during percutaneous coronary intervention (PCI) procedure. We aimed to identify differences in radiation dose, fluoroscopy and procedural times in Hybrid DES+ multiple BVS (Absorb, Abbott Inc., USA) implantation (hybrid metal/scaffold jacket) versus multiple III generation Drug-eluting stents (DES) (full-metal jacket) in patients with long and diffuse coronary artery disease of the left anterior descending (LAD) coronary artery. METHODS/MATERIALS: Patients with long and diffuse LAD disease were enrolled in a registry from 1st February 2015 to 1st February 2017. Patients treated with hybrid DES/BVS (at least three) jacket (n=72 procedure) were compared with a 2:1 matched cohort of exclusive multiple overlapped DES (full-metal jacket) patients in the same period (n=114 procedures). RESULTS: Patients had similar baseline characteristics due to matching. Radiation exposure (6035.7±2846.8 vs 4251.1±1787.3cGy∗cm2, p<0.0001, Δ=1784.5±1055.6), fluoroscopy time (16.2±4.5 vs 9.1±2.4, p<0.0001) and procedure time (64.2±18.5 vs 5 8.7±13.5, p=0.02) were higher in patients treated using hybrid metal/scaffold jacket compared that regular full-metal jacket. CONCLUSION: The use of hybrid metal/scaffold jacket for the treatment of long and diffuse disease of LAD is associated with a higher fluoroscopy time and radiation exposure compared to full-metal jacket, quantifiable in approximately 35%.

The amyloidogenic light chain is a stressor that sensitizes plasma cells to proteasome inhibitor toxicity.

Systemic light chain (AL) amyloidosis is caused by the clonal production of an unstable immunoglobulin light chain (LC), which affects organ function systemically. Although pathogenic LCs have been characterized biochemically, little is known about the biology of amyloidogenic plasma cells (PCs). Intrigued by the unique response rates of AL amyloidosis patients to the first-in-class proteasome inhibitor (PI) bortezomib, we purified and investigated patient-derived AL PCs, in comparison with primary multiple myeloma (MM) PCs, the prototypical PI-responsive cells. Functional, biochemical, and morphological characterization revealed an unprecedented intrinsic sensitivity of AL PCs to PIs, even higher than that of MM PCs, associated with distinctive organellar features and expression patterns indicative of cellular stress. These consisted of expanded endoplasmic reticulum (ER), perinuclear mitochondria, and a higher abundance of stress-related transcripts, and were consistent with reduced autophagic control of organelle homeostasis. To test whether PI sensitivity stems from AL LC production, we engineered PC lines that can be induced to express amyloidogenic and nonamyloidogenic LCs, and found that AL LC expression alters cell growth and proteostasis and confers PI sensitivity. Our study discloses amyloidogenic LC production as an intrinsic PC stressor, and identifies stress-responsive pathways as novel potential therapeutic targets. Moreover, we contribute a cellular disease model to dissect the biology of AL PCs.

Impact of Operators' Height on Individual Radiation Exposure Measurements During Catheter-Based Cardiovascular Interventions.

AIM: This study is aimed to evaluate the impact of an operators' height on personal radiation exposure measurements during cardiovascular interventional procedures. Based upon both clinical data and phantom simulation, a new approach for monitoring an individual's exposure is proposed. METHODS: The clinical component of this study was composed of the operators and staff in a single center full service cardiovascular laboratory being divided into 2 groups based upon their height: group A included all individuals whose height was <165 cm; group B included the individuals >165 cm. All operators wore a standard TLD dosimeter at all times with doses recorded for 12 months. To support these clinical findings, a second investigation was performed utilizing a phantom. Measurements were obtained at 100 and 135 cm from the radiation source during simulation of different cardiovascular interventional procedures. RESULTS: The radiation dose measured from the personal dosimeters identified that Group A, operators <165 cm, had significantly higher doses than those recorded in Group B, operators >165 cm, when compared among individuals performing similar tasks (physicians, technicians, and nurses): 4.55 ± 4.0 (Group A) versus 1.95 ± 1.0 (Group B) mSv (P < 0.01). During procedure simulation with the phantom, the doses measured were similarly significantly higher if measured at 100 cm than at 135 cm from the radiation source. CONCLUSION: This study suggests that the height from radiation source does impact the measured dose from an operator worn personal TLD. This was operator specific, consistent thought-out multiple procedures, and confined with phantom measurements.

A plastic SQSTM1/p62-dependent autophagic reserve maintains proteostasis and determines proteasome inhibitor susceptibility in multiple myeloma cells.

Multiple myeloma (MM) is the paradigmatic proteasome inhibitor (PI) responsive cancer, but many patients fail to respond. An attractive target to enhance sensitivity is (macro)autophagy, recently found essential to bone marrow plasma cells, the normal counterpart of MM. Here, integrating proteomics with hypothesis-driven strategies, we identified the autophagic cargo receptor and adapter protein, SQSTM1/p62 as an essential component of an autophagic reserve that not only synergizes with the proteasome to maintain proteostasis, but also mediates a plastic adaptive response to PIs, and faithfully reports on inherent PI sensitivity. Lentiviral engineering revealed that SQSTM1 is essential for MM cell survival and affords specific PI protection. Under basal conditions, SQSTM1-dependent autophagy alleviates the degradative burden on the proteasome by constitutively disposing of substantial amounts of ubiquitinated proteins. Indeed, its inhibition or stimulation greatly sensitized to, or protected from, PI-induced protein aggregation and cell death. Moreover, under proteasome stress, myeloma cells selectively enhanced SQSTM1 de novo expression and reset its vast endogenous interactome, diverting SQSTM1 from signaling partners to maximize its association with ubiquitinated proteins. Saturation of such autophagic reserve, as indicated by intracellular accumulation of undigested SQSTM1-positive aggregates, specifically discriminated patient-derived myelomas inherently susceptible to PIs from primarily resistant ones. These aggregates correlated with accumulation of the endoplasmic reticulum, which comparative proteomics identified as the main cell compartment targeted by autophagy in MM. Altogether, the data integrate autophagy into our previously established proteasome load-versus-capacity model, and reveal SQSTM1 aggregation as a faithful marker of defective proteostasis, defining a novel prognostic and therapeutic framework for MM.

Autophagy in plasma cell pathophysiology.

Plasma cells (PCs) are the effectors responsible for antibody (Ab)-mediated immunity. They differentiate from B lymphocytes through a complete remodeling of their original structure and function. Stress is a constitutive element of PC differentiation. Macroautophagy, conventionally referred to as autophagy, is a conserved lysosomal recycling strategy that integrates cellular metabolism and enables adaptation to stress. In metazoa, autophagy plays diverse roles in cell differentiation. Recently, a number of autophagic functions have been recognized in innate and adaptive immunity, including clearance of intracellular pathogens, inflammasome regulation, lymphocyte ontogenesis, and antigen presentation. We identified a previously unrecognized role played by autophagy in PC differentiation and activity. Following B cell activation, autophagy moderates the expression of the transcriptional repressor Blimp-1 and immunoglobulins through a selective negative control exerted on the size of the endoplasmic reticulum and its stress signaling response, including the essential PC transcription factor, XBP-1. This containment of PC differentiation and function, i.e., Ab production, is essential to optimize energy metabolism and viability. As a result, autophagy sustains Ab responses in vivo. Moreover, autophagy is an essential intrinsic determinant of long-lived PCs in their as yet poorly understood bone marrow niche. In this essay, we discuss these findings in the context of the established biological functions of autophagy, and their manifold implications for adaptive immunity and PC diseases, in primis multiple myeloma.

MHC class II transactivator is an in vivo regulator of osteoclast differentiation and bone homeostasis co-opted from adaptive immunity.

The molecular networks controlling bone homeostasis are not fully understood. The common evolution of bone and adaptive immunity encourages the investigation of shared regulatory circuits. MHC Class II Transactivator (CIITA) is a master transcriptional co-activator believed to be exclusively dedicated for antigen presentation. CIITA is expressed in osteoclast precursors, and its expression is accentuated in osteoporotic mice. We thus asked whether CIITA plays a role in bone biology. To this aim, we fully characterized the bone phenotype of two mouse models of CIITA overexpression, respectively systemic and restricted to the monocyte-osteoclast lineage. Both CIITA-overexpressing mouse models revealed severe spontaneous osteoporosis, as assessed by micro-computed tomography and histomorphometry, associated with increased osteoclast numbers and enhanced in vivo bone resorption, whereas osteoblast numbers and in vivo bone-forming activity were unaffected. To understand the underlying cellular and molecular bases, we investigated ex vivo the differentiation of mutant bone marrow monocytes into osteoclasts and immune effectors, as well as osteoclastogenic signaling pathways. CIITA-overexpressing monocytes differentiated normally into effector macrophages or dendritic cells but showed enhanced osteoclastogenesis, whereas CIITA ablation suppressed osteoclast differentiation. Increased c-fms and receptor activator of NF-κB (RANK) signaling underlay enhanced osteoclast differentiation from CIITA-overexpressing precursors. Moreover, by extending selected phenotypic and cellular analyses to additional genetic mouse models, namely MHC Class II deficient mice and a transgenic mouse line lacking a specific CIITA promoter and re-expressing CIITA in the thymus, we excluded MHC Class II expression and T cells from contributing to the observed skeletal phenotype. Altogether, our study provides compelling genetic evidence that CIITA, the molecular switch of antigen presentation, plays a novel, unexpected function in skeletal homeostasis, independent of MHC Class II expression and T cells, by exerting a selective and intrinsic control of osteoclast differentiation and bone resorption in vivo.

Estudio de la compulsión glucídica y su relación con el perfil antropométrico y metabólico en un grupo de mujeres adultas argentinas / Carbohydrate compulsion study and its relationship with anthropometric

En el acto de comer, además de numerosas hormonas y sistemas, participa un mecanismo de placer/recompensa que obedece a estímulos específicos y naturales. Objetivos: Asociar la compulsión glucídica con perfil antropométrico y metabólico en mujeres adultas argentinas. Metodología: Diseño descriptivo transversal en muestra voluntaria no probabilística de mujeres mayores de 20 años, asistentes por primera vez a Consulta Nutricional de Fundación para la Investigación de Enfermedades Endocrino Metabólicas durante 2011-2012. Variable dependiente: Compulsión Glucídica (deseo irresistible consumo carbohidratos y sensación de calma posterior). Variables independientes: Edad y etapa biológica: edad fértil, pre y postmenopausia, estilo de vida (hábito tabáquico, consumo alcohol y sedentarismo), perfil antropométrico (IMC>25 kg/m2 y circunferencia de cintura: CC>88cm), perfil metabólico (HDL-C, insulinemia y TG expresados en mg/dl y a través de HOMA-R>2,5 y TG/HDL-C>3,0), perfil tiroideo (eutiroideas/hipotiroideas). Análisis estadístico por SPSS 15.0 calculando, Odds Ratio (OR), intervalo de confianza (IC) del 95%, X2, prueba de Fisher y correlación de Pearson con nivel de significación estadística p< 0,05. Resultados: Muestra de 164 mujeres 50,5 ± 10,7 años. El 49,4% fueron postmenopáusicas. El 87,7% presentó sobrepeso u obesidad y 67,1% CC aumentada. El 47% presentó HOMA-R aumentada y el 22,6% TG/HDL elevada. El 59,1% prefirió sabor dulce, 73,8% picotea entre comidas y 81,7% compulsión glucídica. Se encontró asociación significativa entre compulsión glucídica y sobrepeso u obesidad (OR: 0,29; IC95%: 0,10-0,79; p=0,01) y circunferencia de cintura aumentada (OR: 0,34; IC95%: 0,15-0,77; p=0,009). Conclusiones: Las mujeres con CC aumentada, y sobrepeso u obesidad, presentaron significativamente más riesgo de compulsiones glucídicas que aquellas con perfil antropométrico normal...

Plasma cells require autophagy for sustainable immunoglobulin production.

The role of autophagy in plasma cells is unknown. Here we found notable autophagic activity in both differentiating and long-lived plasma cells and investigated its function through the use of mice with conditional deficiency in the essential autophagic molecule Atg5 in B cells. Atg5(-/-) differentiating plasma cells had a larger endoplasmic reticulum (ER) and more ER stress signaling than did their wild-type counterparts, which led to higher expression of the transcriptional repressor Blimp-1 and immunoglobulins and more antibody secretion. The enhanced immunoglobulin synthesis was associated with less intracellular ATP and more death of mutant plasma cells, which identified an unsuspected autophagy-dependent cytoprotective trade-off between immunoglobulin synthesis and viability. In vivo, mice with conditional deficiency in Atg5 in B cells had defective antibody responses, complete selection in the bone marrow for plasma cells that escaped Atg5 deletion and fewer antigen-specific long-lived bone marrow plasma cells than did wild-type mice, despite having normal germinal center responses. Thus, autophagy is specifically required for plasma cell homeostasis and long-lived humoral immunity.

Pivotal Advance: Protein synthesis modulates responsiveness of differentiating and malignant plasma cells to proteasome inhibitors.

A previously unsuspected, considerable proportion of newly synthesized polypeptides are hydrolyzed rapidly by proteasomes, possibly competing with endogenous substrates and altering proteostasis. In view of the anti-cancer effects of PIs, we set out to achieve a quantitative assessment of proteasome workload in cells hallmarked by different PI sensitivity, namely, a panel of MM cells, and in a dynamic model of plasma cell differentiation, a process that confers exquisite PI sensitivity. Our results suggest that protein synthesis is a key determinant of proteasomal proteolytic burden and PI sensitivity. In different MM cells and in differentiating plasma cells, the average proteolytic work accomplished per proteasome ranges over different orders of magnitude, an unexpected degree of variability, with increased workload invariably associated to increased PI sensitivity. The unfavorable load-versus-capacity balance found in highly PI-sensitive MM lines is accounted for by a decreased total number of immunoproteasomes/cell coupled to enhanced generation of RDPs. Moreover, indicative of cause-effect relationships, attenuating general protein synthesis by the otherwise toxic agent CHX reduces PI sensitivity in activated B and in MM cells. Our data support the view that in plasma cells protein synthesis contributes to determine PI sensitivity by saturating the proteasomal degradative capacity. Quantitating protein synthesis and proteasome workload may thus prove crucial to design novel negative proteostasis regulators against cancer.

The proteasome load versus capacity balance determines apoptotic sensitivity of multiple myeloma cells to proteasome inhibition.

Proteasome inhibitors (PIs) are effective against multiple myeloma (MM), but the mechanisms of action and bases of individual susceptibility remain unclear. Recent work linked PI sensitivity to protein synthesis and proteasome activity, raising the question whether different levels of proteasome expression and workload underlie PI sensitivity in MM cells (MMCs). Exploiting human MM lines characterized by differential PI sensitivity, we report that highly sensitive MMCs express lower proteasome levels and higher proteasomal workload than relatively PI-resistant MMCs, resulting in the accumulation of polyubiquitinated proteins at the expense of free ubiquitin (proteasome stress). Manipulating proteasome expression or workload alters apoptotic sensitivity to PI, demonstrating a cause-effect relationship between proteasome stress and apoptotic responses in MMCs. Intracellular immunostaining in primary, patient-derived MMCs reveals that polyubiquitinated proteins hallmark neoplastic plasma cells, in positive correlation with immunoglobulin (Ig) content, both intra- and interpatient. Moreover, overall proteasome activity of primary MMCs inversely correlates with apoptotic sensitivity to PI. Altogether, our data indicate that the balance between proteasome workload and degradative capacity represents a critical determinant of apoptotic sensitivity of MMCs to PI, potentially providing a framework for identifying indicators of responsiveness and designing novel combination therapies.

Dampening Ab responses using proteasome inhibitors following in vivo B cell activation.

Upon encounter with Ag, B lymphocytes undergo terminal differentiation into plasma cells, highly specialized Ab secretors that mediate humoral immune responses. Profound changes adapt cellular morphology and proteome to the new secretory functions. Although a massive secretory activity is expected to require an efficient ubiquitin-proteasome degradation system, recent in vitro studies have surprisingly revealed that the proteasome function sharply decreases during plasma cell development, thereby limiting the proteolytic capacity. We challenged this paradigm in mouse models of B cell activation, and observed that following polyclonal activation, proteasome activity decreases more than previously reported in vitro. This decrease is linked to enhanced apoptosis after treatment with the potent anti-myeloma proteasome inhibitor PS-341. Accordingly, in vivo treatment with PS-341 decreases Ab titres in T-dependent and -independent mouse immunization models. This study provides the rationale for limiting the activity of Ab-secreting cells in vivo by impacting proteasome function.

Impact of intracardiac echocardiography on radiation exposure during adult congenital heart disease catheter-based interventions.

BACKGROUND: Intracardiac echocardiography (ICE) is a widespread approach in many cardiovascular procedures in which it has the potential to reduce the fluoroscopy time and patients radiation exposure. We sought to assess the patient radiation exposure during transcatheter closure of interatrial communications with and without ICE-guidance. METHODS: In a prospective consecutive series of 25 consecutive patients who underwent transcatheter closure of interatrial communications between May and October 2005 with (15 patients) and without (10 patients) ICE-guidance in a single secondary care referral centre, we measured the dose-area product (DAP), the fluoroscopy dose-area product (FDAP), the total dose-area product (TDAP), and the mean procedural time. RESULTS: In patients underwent ICE-guided transcatheter closure procedure the mean fluoroscopy time, the mean DAP, mean FDAP, and mean TDAP resulted significantly lower than in control patients: 2.0 +/- 0.21 (range 1.6-2.2) versus 5.05 +/- 0.54 (range 4.2-5.8) minutes (P < 0.001) , 13.72 +/- 9.03 (range 11.36-14.63) versus 21.95 +/- 6.93 (range 20.90-23.93) Gycm2 (P < 0.001), 8.25 +/- 1.22 (range 6.60-9.50) versus 20.15 +/- 8.83 (range 18.90-20.93) Gycm2 (P < 0.001), and 29.33 +/- 1.51(range 27.16-31.00) versus 32.61 +/- 2.53 (range 29.20-35.55) Gycm2 (P < 0.01). On the contrary, the mean procedural time, was significantly higher in ICE-guided transcatheter closure patients: 30.2 +/- 2.45 (range 23-40) versus 24.5 +/- 2.45 (range 24-31) minutes (P = 0.03). CONCLUSION: The radiation exposure during ICE-guided transcatheter closure of interatrial communications in this group of patients was quite lower than that reported in literature for such procedures and compared favourably with radiation exposure of patients in whom the intervention was performed without ICE guidance.

Progressively impaired proteasomal capacity during terminal plasma cell differentiation.

After few days of intense immunoglobulin (Ig) secretion, most plasma cells undergo apoptosis, thus ending the humoral immune response. We asked whether intrinsic factors link plasma cell lifespan to Ig secretion. Here we show that in the late phases of plasmacytic differentiation, when antibody production becomes maximal, proteasomal activity decreases. The excessive load for the reduced proteolytic capacity correlates with accumulation of polyubiquitinated proteins, stabilization of endogenous proteasomal substrates (including Xbp1s, IkappaBalpha, and Bax), onset of apoptosis, and sensitization to proteasome inhibitors (PI). These events can be reproduced by expressing Ig-mu chain in nonlymphoid cells. Our results suggest that a developmental program links plasma cell death to protein production, and help explaining the peculiar sensitivity of normal and malignant plasma cells to PI.