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1
Saini, Mehak, et Surender K. Grewal. « Transmit Antenna Selection Methods For Mimo Systems In Wireless Communications ». Journal of University of Shanghai for Science and Technology 23, no 08 (16 août 2021) : 523–31. http://dx.doi.org/10.51201/jusst/21/08424.
Texte intégralRésumé :
Though MIMO systems improve performance of a wireless communication network by the usage of multiple antennas, demand of distinct set of RF chain (i.e., electronic components required for antenna transmission and reception, in wireless communication) for all the antennas leads to an increase in complexity and cost. Antenna selection technique of MIMO has proved to be a good means to solve this issue. Antenna Selection methods find optimal number of antennas required out of the total antennas present in the MIMO (Multiple Input Multiple Output) system. The selection of antenna can be performed at both ends of the communication network i.e., transmitter or receiver. In this paper, an overview of various Transmit Antenna Selection techniques for various MIMO systems is presented.
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Teodorescu, Laurenţiu, et Gabriel Dima. « High Performance Broadcast Receiver Based on Obsolete Technology ». Sensors 22, no 18 (8 septembre 2022) : 6784. http://dx.doi.org/10.3390/s22186784.
Texte intégralRésumé :
Since its inception, the electronics industry has mass-produced equipment. The fast evolution of electronic technologies made obsolete the entire generation of products and even technologies. Until the government issued regulations and guidelines on how to address the issue of reuse of obsolete electronic equipment, with special regard to the ones still operating (e.g., give it to family/friends, donate to charity, or sell to individuals or recycling companies), most of it was thrown out with usual rubbish, with a destructive effect on the environment. This paper presents the design techniques and methods for revaluation of obsolete vacuum tube analog receivers, with a focus on the manufacturing steps of a high-performance receiver. The choice of receiver type is not accidental at all, since tube technology is still a real success among audiophiles many providers offer vacuum tube amplifiers at considerably high prices. The redesign implied the original FM unit replacement with a DSP-based AM/FM tuner while the AM RF vacuum tube section has been preserved with the original architecture to allow the reception of the broadcast stations for the long-wave band and the alternative operation with the silicon tuner for the medium-wave and short-wave bands. The electrical performances of the modified receiver in terms of reliability, sensitivity, selectivity, and distortions on the reception chain are clearly superior to the original one, while the power consumption of the RF section is reduced more than 10 times from 11.5 W–15.5 W to 1 W. Last, but not least important, the proposed solution implied the use of few additional parts and resources and extended significantly the lifetime of the original vacuum tubes receiver. The work has been developed to serve as an example of how obsolete electronic equipment can be redesigned and reused avoiding its complete recycling or even worse, its disposal with usual rubbish. It has been imagined and performed as the initial step in launching a professional student contest on the reuse/redesign of obsolete equipment aimed at raising awareness regarding the issue of pollution with e-waste amongst students from the electronic departments of Romanian technical universities.
3
Marshall, Aaron J., Noelle Doyen, Laurent A. Bentolila, Christopher J. Paige et Gillian E. Wu. « Terminal Deoxynucleotidyl Transferase Expression During Neonatal Life Alters DH Reading Frame Usage and Ig-Receptor-Dependent Selection of V Regions ». Journal of Immunology 161, no 12 (15 décembre 1998) : 6657–63. http://dx.doi.org/10.4049/jimmunol.161.12.6657.
Texte intégralRésumé :
Abstract During neonatal life, Ig diversity is limited in many respects. The absence of terminal deoxynucleotidyl transferase (TdT) expression with the consequent lack of nontemplated addition during the neonatal period, coupled with the predominant usage of a single DH reading frame (RF), leads to severe limitations of diversity in the CDR3 region of Ig heavy (H) chains. The neonatal Ig H chain repertoire is also characterized by restricted VH usage, with predominant expression of certain VH segments, such as VH81x, that are rarely evident during adult life. In this report, we examine the effect of enforced TdT expression on the neonatal repertoire of VH81xDJH rearrangements. We find that TdT synthesis abrogates DH RF bias during the fetal/neonatal period through a Ig-receptor-independent mechanism. These findings suggest that DH RF bias during neonatal life is determined largely by homology-directed joining. We also find that TdT synthesis alters the selection of productively rearranged VH81xDJH alleles in the neonatal spleen through a Ig-receptor-dependent mechanism. Analysis of predicted CDR3 amino acid sequences indicates that positive selection of VH81x-encoded H chains is correlated with the presence of a consensus sequence immediately adjacent to the VH segment. These data support the hypothesis that the CDR3 region is critical in determining the ability of VH81x-encoded H chains to form functional receptors that support positive selection of B lymphocytes. Together, our results demonstrate that TdT can indirectly influence the Ig repertoire by influencing both receptor-dependent and receptor-independent selection processes.
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krishna, Mr P. V. Murali, et Lade Surendra Babu. « HYBRID BEAMFORMING FOR MULTIBEAM PHASED ARRAY RECEVIERS ». INTERANTIONAL JOURNAL OF SCIENTIFIC RESEARCH IN ENGINEERING AND MANAGEMENT 07, no 12 (30 décembre 2023) : 1–3. http://dx.doi.org/10.55041/ijsrem27817.
Texte intégralRésumé :
In the search for enhanced wireless communication systems, multibeam phased array receivers have gained prominence. They promise to significantly boost data rates, reduce latency, and improve reliability. However, implementing multibeam receivers with traditional beamforming techniques can be challenging due to the high computational demands and the need for multiple radio frequency (RF) chains. Hybrid beamforming combines the advantages of digital and analog beamforming to strike a balance between performance and complexity. Our research delves into the following aspects of Hybrid beamforming for multibeam phased array receivers: Reduced Hardware Complexity: By blending digital and analog beamforming, we reduce the number of required RF chains, making multibeam receivers more cost-effective. Enhanced Beam Steering: Hybrid beamforming maintains precise control over multiple beams, ensuring efficient signal reception and transmission. Real-World Applications: We discuss practical applications in 5G and beyond, satellite communications, and radar systems. The paper delves into the fundamental concepts of analog and digital beamforming, illustrating their respective strengths and limitations. It then presents the architecture of hybrid beamforming systems, emphasizing the synergistic integration of analog and digital components. Special attention is given to the design considerations of beamforming networks, antenna arrays, and the beam steering mechanism. KEYWORDS Hybrid Beamforming , Phased Array , Multi-Beam , Analog Beamforming , Digital Beamforming , Beamforming Networks , Antenna Array , Beam Steering , Spatial Multiplexing , Precoding , Channel Estimation , Interference Mitigation , Power Consumption , Millimeter Wave (mmWave) , 5G and Beyond .
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De Re, Valli, Salvatore De Vita, Alessandra Marzotto, Maurizio Rupolo, Annunziata Gloghini, Barbara Pivetta, Daniela Gasparotto, Antonino Carbone et Mauro Boiocchi. « Sequence analysis of the immunoglobulin antigen receptor of hepatitis C virus–associated non-Hodgkin lymphomas suggests that the malignant cells are derived from the rheumatoid factor–producing cells that occur mainly in type II cryoglobulinemia ». Blood 96, no 10 (15 novembre 2000) : 3578–84. http://dx.doi.org/10.1182/blood.v96.10.3578.
Texte intégralRésumé :
Abstract Analysis of the immunoglobulin receptor (IGR) variable heavy- and light-chain sequences on 17 hepatitis C virus (HCV)-associated non-Hodgkin lymphomas (NHLs) (9 patients also had type II mixed cryoglobulinemia [MC] syndrome and 8 had NHL unrelated to MC) and analysis of intraclonal diversity on 8 of them suggest that such malignant lymphoproliferations derive from an antigen-driven pathologic process, with a selective pressure for the maintenance of a functional IgR and a negative pressure for additional amino acid mutations in the framework regions (FRs). For almost all NHLs, both heavy- and light-chain complementarity-determining regions (CDR3) showed the highest similarity to antibodies with rheumatoid factor (RF) activity that have been found in the MC syndrome, thus suggesting that a common antigenic stimulus is involved in MC syndrome and in HCV-associated lymphomagenesis. Moreover, because HCV is the recognized pathologic agent of MC and the CDR3 amino acid sequences of some HCV-associated NHLs also present a high homology for antibody specific for the E2 protein of HCV, it may be reasonable to speculate that HCV E2 protein is one of the chronic antigenic stimuli involved in the lymphomagenetic process. Finally, the use of specific segments, in particular the D segment, in assembling the IgH chain of IgR seems to confer B-cell disorders with the property to produce antibody with RF activity, which may contribute to the manifestation of an overt MC syndrome.
6
De Re, Valli, Salvatore De Vita, Alessandra Marzotto, Maurizio Rupolo, Annunziata Gloghini, Barbara Pivetta, Daniela Gasparotto, Antonino Carbone et Mauro Boiocchi. « Sequence analysis of the immunoglobulin antigen receptor of hepatitis C virus–associated non-Hodgkin lymphomas suggests that the malignant cells are derived from the rheumatoid factor–producing cells that occur mainly in type II cryoglobulinemia ». Blood 96, no 10 (15 novembre 2000) : 3578–84. http://dx.doi.org/10.1182/blood.v96.10.3578.h8003578_3578_3584.
Texte intégralRésumé :
Analysis of the immunoglobulin receptor (IGR) variable heavy- and light-chain sequences on 17 hepatitis C virus (HCV)-associated non-Hodgkin lymphomas (NHLs) (9 patients also had type II mixed cryoglobulinemia [MC] syndrome and 8 had NHL unrelated to MC) and analysis of intraclonal diversity on 8 of them suggest that such malignant lymphoproliferations derive from an antigen-driven pathologic process, with a selective pressure for the maintenance of a functional IgR and a negative pressure for additional amino acid mutations in the framework regions (FRs). For almost all NHLs, both heavy- and light-chain complementarity-determining regions (CDR3) showed the highest similarity to antibodies with rheumatoid factor (RF) activity that have been found in the MC syndrome, thus suggesting that a common antigenic stimulus is involved in MC syndrome and in HCV-associated lymphomagenesis. Moreover, because HCV is the recognized pathologic agent of MC and the CDR3 amino acid sequences of some HCV-associated NHLs also present a high homology for antibody specific for the E2 protein of HCV, it may be reasonable to speculate that HCV E2 protein is one of the chronic antigenic stimuli involved in the lymphomagenetic process. Finally, the use of specific segments, in particular the D segment, in assembling the IgH chain of IgR seems to confer B-cell disorders with the property to produce antibody with RF activity, which may contribute to the manifestation of an overt MC syndrome.
7
Toptaş, Bahar, Ali Metin Kafadar, Canan Cacina, Saime Turan, Leman Melis Yurdum, Nihal Yiğitbaşı, Muhammed Oğuz Gökçe, Ümit Zeybek et Ilhan Yaylım. « The Vitamin D Receptor (VDR) Gene Polymorphisms in Turkish Brain Cancer Patients ». BioMed Research International 2013 (2013) : 1–6. http://dx.doi.org/10.1155/2013/295791.
Texte intégralRésumé :
Objective. It has been stated that brain cancers are an increasingly serious issue in many parts of the world. The aim of our study was to determine a possible relationship between Vitamin D receptor (VDR) gene polymorphisms and the risk of glioma and meningioma.Methods. We investigated the VDR Taq-I and VDR Fok-I gene polymorphisms in 100 brain cancer patients (including 44 meningioma cases and 56 glioma cases) and 122 age-matched healthy control subjects. This study was performed by polymerase chain reaction-based restriction fragment length polymorphism (RF LP).Results. VDR Fok-I ff genotype was significantly increased in meningioma patients (15.9%) compared with controls (2.5%), and carriers of Fok-I ff genotype had a 6.47-fold increased risk for meningioma cases. There was no significant difference between patients and controls for VDR Taq-I genotypes and alleles.Conclusions. We suggest that VDR Fok-I genotypes might affect the development of meningioma.
8
Shankar, Divya, Giovanna Merchand-Reyes, Nathaniel J. Buteyn, Ramasamy Santhanam, Huiqing Fang, Krishan Kumar, Xiaokui Mo et al. « Inhibition of BET Proteins Regulates Fcγ Receptor Function and Reduces Inflammation in Rheumatoid Arthritis ». International Journal of Molecular Sciences 24, no 8 (21 avril 2023) : 7623. http://dx.doi.org/10.3390/ijms24087623.
Texte intégralRésumé :
Overactivation of immune responses is a hallmark of autoimmune disease pathogenesis. This includes the heightened production of inflammatory cytokines such as Tumor Necrosis Factor α (TNFα), and the secretion of autoantibodies such as isotypes of rheumatoid factor (RF) and anticitrullinated protein antibody (ACPA). Fcγ receptors (FcγR) expressed on the surface of myeloid cells bind Immunoglobulin G (IgG) immune complexes. Recognition of autoantigen-antibody complexes by FcγR induces an inflammatory phenotype that results in tissue damage and further escalation of the inflammatory response. Bromodomain and extra-terminal protein (BET) inhibition is associated with reduced immune responses, making the BET family a potential therapeutic target for autoimmune diseases such as rheumatoid arthritis (RA). In this paper, we examined the BET inhibitor PLX51107 and its effect on regulating FcγR expression and function in RA. PLX51107 significantly downregulated expression of FcγRIIa, FcγRIIb, FcγRIIIa, and the common γ-chain, FcϵR1-γ, in both healthy donor and RA patient monocytes. Consistent with this, PLX51107 treatment attenuated signaling events downstream of FcγR activation. This was accompanied by a significant decrease in phagocytosis and TNFα production. Finally, in a collagen-induced arthritis model, PLX51107-treatment reduced FcγR expression in vivo accompanied by a significant reduction in footpad swelling. These results suggest that BET inhibition is a novel therapeutic approach that requires further exploration as a treatment for patients with RA.
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Al-Awadhi, Adel M., Mohammad Z. Haider, Jalaja Sukumaran, Eman AH Hasan et Youssef A. Bartella. « The Protein Tyrosine Phosphatase Non-receptor Type N22 (PTPN22) Gene Functional Polymorphism (1858T) is not Associated with Rheumatoid Arthritis in Kuwaiti Patients ». Open Rheumatology Journal 15, no 1 (12 juillet 2021) : 45–50. http://dx.doi.org/10.2174/1874312902115010045.
Texte intégralRésumé :
Background: Rheumatoid Arthritis (RA) is a chronic disorder characterized by an inflammation of synovial tissue in joints resulting in pain, deformities and affects the quality of life. The gene for protein tyrosine phosphatase non-receptor type 22 (PTPN22) encodes a lymphoid specific phosphatase (LYP), which serves as a negative regulator of T lymphocyte activation and is associated with a number of autoimmune/chronic diseases in various ethnic groups. Objective: This study was undertaken to investigate an association between PTPN22 gene functional polymorphism (C1858T; rs2476601) and rheumatoid arthritis (RA) in Kuwaiti Arabs. The frequency of this candidate locus was compared between Kuwaiti RA patients and the controls and with that reported from other populations. Methods: The study was carried out in 191 Kuwaiti RA patients and 214 healthy controls. The diagnosis of RA was carried out according to the guidelines of the American College of Rheumatology (ACR). The genotypes of PTPN22 gene (C1858T) polymorphism were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and confirmed by DNA sequence analysis in RA patients and controls. Results: The TT genotype of PTPN22 gene functional polymorphism C1858T was found in 2/191 (1%) in RA patients compared to 2/214 (1%) in the controls (P = 1.0). In contrast, heterozygous CT genotype was detected in 3/191 (1.57%) RA patients compared to 32/214 (14.9%) in the controls. The CC genotype was detected in 186/191 (97.38%), RA patients while it was detected in 180/214 (84.1%) of the controls. The two RA patients who carried the homozygous variant (TT) genotype were both positive for rheumatoid factor (RF) and did not have any extra-articular manifestations. Amongst the Kuwaiti RA patients, 27% had a family history of RA. No correlation was found between the activity/severity of the disease and PTPN22 gene polymorphism genotypes. Conclusion: This study did not find an association between the PTPN22 gene functional polymorphism (C1858T) and clinical manifestation and activity/severity of RA in Kuwaiti Arabs. This is in sharp contrast to previous reports from Caucasian and some other populations in which a positive association of PTPN22 gene (C1858T) polymorphism with genetic susceptibility to RA has been reported.
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Tena-Sempere, M., PR Manna, FP Zhang, L. Pinilla, LC Gonzalez, C. Dieguez, I. Huhtaniemi et E. Aguilar. « Molecular mechanisms of leptin action in adult rat testis : potential targets for leptin-induced inhibition of steroidogenesis and pattern of leptin receptor messenger ribonucleic acid expression ». Journal of Endocrinology 170, no 2 (1 août 2001) : 413–23. http://dx.doi.org/10.1677/joe.0.1700413.
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Leptin, the product of the ob gene, is a pivotal signal in the regulation of neuroendocrine function and fertility. Although much of the action of leptin in the control of the reproductive axis is exerted at the hypothalamic level, some direct effects of leptin on male and female gonads have also been reported. Indeed, recent evidence demonstrated that leptin is able to inhibit testosterone secretion at the testicular level. However, the molecular mechanisms behind this effect remain unclear. The focus of this study was twofold: (1) to identify potential targets for leptin-induced inhibition of steroidogenesis, and (2) to characterize in detail the pattern of expression and cellular distribution of leptin receptor (Ob-R) mRNA in adult rat testis. In pursuit of the first goal, slices of testicular tissue from adult rats were incubated with increasing concentrations of recombinant leptin (10(-9)--10(-7 )M) in the presence of human chorionic gonadotropin (hCG; 10 IU/ml). In this setting, testosterone secretion in vitro was monitored, and expression levels of mRNAs encoding steroidogenic factor 1 (SF-1), steroidogenic acute regulatory protein (StAR), cytochrome P450 cholesterol side-chain cleavage enzyme (P450 scc) and 17 beta-hydroxysteroid dehydrogenase type III (17 beta-HSD) were assessed by Northern hybridization. In pursuit of the second goal, the pattern of cellular expression of the Ob-R gene in adult rat testis was evaluated by in situ hybridization using a riboprobe complementary to all Ob-R isoforms. In addition, testicular expression levels of the different Ob-R isoforms, previously identified in the hypothalamus, were analyzed by means of semi-quantitative RT-PCR. In keeping with our previous data, recombinant leptin significantly inhibited hCG-stimulated testosterone secretion. In this context, leptin, in a dose-dependent manner, was able to co-ordinately decrease the hCG-stimulated expression levels of SF-1, StAR and P450 scc mRNAs, but it did not affect those of 17 beta-HSD type III. In situ hybridization analysis showed a scattered pattern of cellular expression of the Ob-R gene within the adult rat testis, including Leydig and Sertoli cells. In addition, assessment of the pattern of expression of Ob-R subtypes revealed that the long Ob-Rb isoform was abundantly expressed in adult rat testis. However, variable levels of expression of Ob-Ra, Ob-Re, and Ob-Rf mRNAs were also detected, whereas those of the Ob-Rc variant were nearly negligible. In conclusion, our results indicate that decreased expression of mRNAs encoding several up-stream elements in the steroidogenic pathway may contribute, at least partially, to leptin-induced inhibition of testicular steroidogenesis. In addition, our data on the pattern of testicular expression of Ob-R isoforms and cellular distribution of Ob-R mRNA may help to further elucidate the molecular mechanisms of leptin action in rat testis.
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« Third-order Single-bit Sigma Delta modulator structure for an RF reception chain for a LTE network ». AUSTRALIAN JOURNAL OF BASIC AND APPLIED SCIENCES, 2018. http://dx.doi.org/10.22587/ajbas.2018.12.7.2.
Texte intégral
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Overson, Devon K., Julia Bresticker, Devin Willey, Fraser Robb, Allen W. Song, Trong-Kha Truong et Dean Darnell. « Numerical simulations of an integrated radio-frequency/wireless coil design for simultaneous acquisition and wireless transfer of magnetic resonance imaging data ». Physics in Medicine & ; Biology, 16 mai 2023. http://dx.doi.org/10.1088/1361-6560/acd614.
Texte intégralRésumé :
Abstract Objective: A novel MRI radio-frequency coil design, termed an integrated RF/wireless (iRFW) coil design, can simultaneously perform MRI signal reception and far-field wireless data transfer with the same coil conductors between the coil in the scanner bore and an access point (AP) on the scanner room wall. The objective of this work is to optimize the design inside the scanner bore to provide a link budget between the coil and the AP for the wireless transmission of MRI data. 

Approach: Electromagnetic simulations were performed at the Larmor frequency of a 3T scanner and in a WiFi wireless communication band to optimize the radius and position of an iRFW coil located near the head of a human model inside the scanner bore, which were validated by performing both imaging and wireless experiments.

Main Results: The simulated iRFW coil with a 40-mm radius positioned near the model forehead provided: a signal-to-noise ratio (SNR) comparable to that of a traditional RF coil with the same radius and position, a power absorbed by the human model within regulatory limits, and a gain pattern in the scanner bore resulting in a link budget of 51.1 dB between the coil and an AP located behind the scanner 3 m from the isocenter, which would be sufficient to wirelessly transfer MRI data acquired with a 16-channel coil array.

Significance: The MRI coil array cable assembly connected to the scanner increases patient setup time, can present a burn risk to patients and is an obstacle to the development of lightweight, flexible, or wearable coil arrays that provide an improved coil sensitivity. Significantly, the RF coaxial cables and corresponding receive chain electronics can be removed from within the scanner by integrating the iRFW coil design into an array for the wireless transmission of MRI data outside of the bore.
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Momen‐Tayefeh, Mehrdad, et Ali Olfat. « Optimizing hybrid beamforming in millimeter‐wave massive multiple‐input multiple‐output systems : A gradient projection approach ». Transactions on Emerging Telecommunications Technologies 35, no 8 (août 2024). http://dx.doi.org/10.1002/ett.5025.
Texte intégralRésumé :
AbstractMillimeter waves (mmWave) present an enticing opportunity for wireless communication due to their substantial bandwidth. However, mitigating signal losses within this spectrum necessitates employing numerous antennas for transmission and reception. In practical scenarios, dedicating individual RF chains to each antenna is often unfeasible. In response to this limitation, our research investigates a hybrid beamforming approach, seeking to optimize spectral efficiency through an alternating optimization (AO) technique. Our goal is to develop an algorithm that can be easily integrated into diverse hybrid beamforming configurations. On the other hand the pursuit of optimizing spectral efficiency while adhering to the constraints imposed by phase shifters results in a non‐convex problem. To confront this challenge, we employ a gradient descent framework combined with projection methods. We introduce the gradient prediction method (GPM), which leads to a closed‐form solution for projection. Simulations underscore that this hybrid beamforming structure can achieve the performance of a fully digital beamforming method when the number of RF chains is twice the total number of data streams, regardless of the number of antennas involved. Furthermore, we will conduct a comparative performance analysis of our proposed algorithm against other established benchmark algorithms to ascertain its superiority.
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Ahmad, Hosam M., Zaki M. Zaki, Asmaa S. Mohamed et Amr E. Ahmed. « Biochemical markers and FokI and TaqI vitamin D receptor genes polymorphism in rheumatoid arthritis ». BMC Medical Genomics 16, no 1 (19 octobre 2023). http://dx.doi.org/10.1186/s12920-023-01668-8.
Texte intégralRésumé :
Abstract Background Previous studies have reported the role of genes in different metabolic processes in the human body, and any variation in gene polymorphisms could lead to disturbances in these processes and different diseases. Objective This study aimed to compare vitamin D receptor (VDR) FokI and TaqI genotypes in terms of parathyroid hormone (PTH) and some biomarkers of inflammation and susceptibility to rheumatoid arthritis (RA) disease. Methods This study included 100 patients with rheumatoid arthritis (RA). Genotyping was performed by polymerase chain reaction (PCR) and examined by specific restriction enzymes using restriction fragment length polymorphism (RFLP). Serum intact PTH, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), rheumatoid factor (RF), and anti-cyclic citrullinated peptide antibodies (ACCPs) levels were measured. Results An increased PTH level (> 65 pg/ml) was found in 8% of patients. No significant differences among FokI and TaqI vitamin D receptor genes polymorphism regarding positive and negative RF or ACCPs were found. A significant difference was found among FokI (p = 0.009) and none in TaqI genotypes regarding intact parathyroid hormone level categories. No significant correlation was found between the serum intact PTH level and ESR or CRP levels (P = 0.13 and 0.28, respectively). The parathyroid hormone level was not a good predictor for RF or ACCPs (P = 0.5 and 0.06, respectively). Conclusion The FokI gene may play a role in controlling PTH levels in patients with RA. There was no significant correlation found between the serum intact PTH level and RA severity according to ESR and CRP inflammatory biomarkers. There are no differences between VDR genes FokI and TaqI polymorphism in terms of RA susceptibility (for RF and ACCPs).
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Heeman, Jessica, Brian J. White, Stefan Van der Stigchel, Jan Theeuwes, Laurent Itti et Douglas P. Munoz. « Saliency response in superior colliculus at the future saccade goal predicts fixation duration during free viewing of dynamic scenes ». Journal of Neuroscience, 21 novembre 2024, e0428242024. http://dx.doi.org/10.1523/jneurosci.0428-24.2024.
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Eye movements in daily life occur in rapid succession and often without a predefined goal. Using a free viewing task, we examined how fixation duration prior to a saccade correlates to visual saliency and neuronal activity in the superior colliculus (SC) at the saccade goal. Rhesus monkeys (three male) watched videos of natural, dynamic, scenes while eye movements were tracked and, simultaneously, neurons were recorded in the superficial and intermediate layers of the superior colliculus (SCs and SCi respectively), a midbrain structure closely associated with gaze, attention, and saliency coding. Saccades that were directed into the neuron’s receptive field (RF) were extrapolated from the data. To interpret the complex visual input, saliency at the RF location was computed during the pre-saccadic fixation period using a computational saliency model. We analyzed if visual saliency and neural activity at the saccade goal predicted pre-saccadic fixation duration. We report three major findings: 1) Saliency at the saccade goal inversely correlated with fixation duration, with motion and edge information being the strongest predictors. 2) SC visual saliency responses in both SCs and SCi were inversely related to fixation duration. 3) SCs neurons, and not SCi neurons, showed higher activation for two consecutive short fixations, suggestive of concurrent saccade processing during free viewing. These results reveal a close correspondence between visual saliency, SC processing, and the timing of saccade initiation during free viewing and are discussed in relation to their implication for understanding saccade initiation during real-world gaze behavior.Significance statementContrary to traditional controlled stimuli/task studies, eye movements in day-to-day life are not discrete events but occur in (rapid) succession and often without a predefined goal. Therefore, the study of visual processing during free viewing of dynamic scenes is an essential step in understanding visual processing in its functional context. We present an investigation into saliency and visual responses in the superior colliculus (SC) during task-free viewing of dynamic videos and their correspondence to saccade initiation. In short, these results show the correspondence between fixation duration, pre-saccadic visual saliency at the saccade goal and SC processing and provide first evidence of a neural correlate of concurrent visual processing across a chain of saccades in the SC during free viewing.
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Zhang, Linjie, Yizhang Deng, Jingbang Yang, Wuguo Deng et Liren Li. « Neurotransmitter receptor-related gene signature as potential prognostic and therapeutic biomarkers in colorectal cancer ». Frontiers in Cell and Developmental Biology 11 (30 novembre 2023). http://dx.doi.org/10.3389/fcell.2023.1202193.
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Background: Colorectal cancer is one of the most common malignant tumors worldwide. A various of neurotransmitter receptors have been found to be expressed in tumor cells, and the activation of these receptors may promote tumor growth and metastasis. This study aimed to construct a novel neurotransmitter receptor-related genes signature to predict the survival, immune microenvironment, and treatment response of colorectal cancer patients.Methods: RNA-seq and clinical data of colorectal cancer from The Cancer Genome Atlas database and Gene Expression Omnibus were downloaded. Neurotransmitter receptor-related gene were collected from publicly available data sources. The Weighted Gene Coexpression Network Analysis (WGCNA), Least Absolute Shrinkage and Selection Operator (LASSO) logistic regression, Support Vector Machine-Recursive Feature Elimination (SVM-RFE), and Random Forest (RF) algorithms were employed to construct the Neurotransmitter receptor-related gene prognostic signature. Further analyses, functional enrichment, CIBERSORTx, The Tumor Immune Single Cell Center (TISCH), survival analysis, and CellMiner, were performed to analyze immune status and treatment responses. Quantitative real-time polymerase chain reaction (qRT-PCR) assays were carried out to confirm the expression levels of prognostic genes.Results: By combining machine learning algorithm and WGCNA, we identified CHRNA3, GABRD, GRIK3, and GRIK5 as Neurotransmitter receptor-related prognostic genes signature. Functional enrichment analyses showed that these genes were enriched with cellular metabolic-related pathways, such as organic acid, inorganic acid, and lipid metabolism. CIBERSORTx and Single cell analysis showed that the high expression of genes were positively correlated with immunosuppressive cells infiltration, and the genes were mainly expressed in cancer-associated fibroblasts and endothelial cells. A nomogram was further built to predict overall survival (OS). The expression of CHRNA3, GABRD, GRIK3, and GRIK5 in cancer cells significantly impacted their response to chemotherapy.Conclusion: A neurotransmitter receptor-related prognostic gene signature was developed and validated in the current study, giving novel sights of neurotransmitter in predicting the prognostic and improving the treatment of CRC.