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1.
Nano Lett ; 24(23): 6948-6956, 2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38810209

RESUMO

The concept of cross-sensor modulation, wherein one sensor modality can influence another's response, is often overlooked in traditional sensor fusion architectures, leading to missed opportunities for enhancing data accuracy and robustness. In contrast, biological systems, such as aquatic animals like crayfish, demonstrate superior sensor fusion through multisensory integration. These organisms adeptly integrate visual, tactile, and chemical cues to perform tasks such as evading predators and locating prey. Drawing inspiration from this, we propose a neuromorphic platform that integrates graphene-based chemitransistors, monolayer molybdenum disulfide (MoS2) based photosensitive memtransistors, and triboelectric tactile sensors to achieve "Super-Additive" responses to weak chemical, visual, and tactile cues and demonstrate contextual response modulation, also referred to as the "Inverse Effectiveness Effect." We hold the view that integrating bio-inspired sensor fusion principles across various modalities holds promise for a wide range of applications.


Assuntos
Astacoidea , Grafite , Molibdênio , Tato , Animais , Molibdênio/química , Grafite/química , Dissulfetos/química
2.
Adv Mater ; 36(13): e2307380, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38069632

RESUMO

Unisensory cues are often insufficient for animals to effectively engage in foraging, mating, and predatory activities. In contrast, integration of cues collected from multiple sensory organs enhances the overall perceptual experience and thereby facilitates better decision-making. Despite the importance of multisensory integration in animals, the field of artificial intelligence (AI) and neuromorphic computing has primarily focused on processing unisensory information. This lack of emphasis on multisensory integration can be attributed to the absence of a miniaturized hardware platform capable of co-locating multiple sensing modalities and enabling in-sensor and near-sensor processing. In this study, this limitation is addressed by utilizing the chemo-sensing properties of graphene and the photo-sensing capability of monolayer molybdenum disulfide (MoS2) to create a multisensory platform for visuochemical integration. Additionally, the in-memory-compute capability of MoS2 memtransistors is leveraged to develop neural circuits that facilitate multisensory decision-making. The visuochemical integration platform is inspired by intricate courtship of Heliconius butterflies, where female species rely on the integration of visual cues (such as wing color) and chemical cues (such as pheromones) generated by the male butterflies for mate selection. The butterfly-inspired visuochemical integration platform has significant implications in both robotics and the advancement of neuromorphic computing, going beyond unisensory intelligence and information processing.


Assuntos
Borboletas , Sinais (Psicologia) , Animais , Masculino , Feminino , Molibdênio , Inteligência Artificial , Cognição
3.
Nat Commun ; 14(1): 6021, 2023 09 27.
Artigo em Inglês | MEDLINE | ID: mdl-37758750

RESUMO

Animal behavior involves complex interactions between physiology and psychology. However, most AI systems neglect psychological factors in decision-making due to a limited understanding of the physiological-psychological connection at the neuronal level. Recent advancements in brain imaging and genetics have uncovered specific neural circuits that regulate behaviors like feeding. By developing neuro-mimetic circuits that incorporate both physiology and psychology, a new emotional-AI paradigm can be established that bridges the gap between humans and machines. This study presents a bio-inspired gustatory circuit that mimics adaptive feeding behavior in humans, considering both physiological states (hunger) and psychological states (appetite). Graphene-based chemitransistors serve as artificial gustatory taste receptors, forming an electronic tongue, while 1L-MoS2 memtransistors construct an electronic-gustatory-cortex comprising a hunger neuron, appetite neuron, and feeding circuit. This work proposes a novel paradigm for emotional neuromorphic systems with broad implications for human health. The concept of gustatory emotional intelligence can extend to other sensory systems, benefiting future humanoid AI.


Assuntos
Comportamento Alimentar , Paladar , Animais , Humanos , Paladar/fisiologia , Comportamento Alimentar/fisiologia , Apetite , Comportamento Animal , Fome/fisiologia
4.
Nano Lett ; 23(11): 5171-5179, 2023 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-37212254

RESUMO

Physically unclonable functions (PUFs) are an integral part of modern-day hardware security. Various types of PUFs already exist, including optical, electronic, and magnetic PUFs. Here, we introduce a novel straintronic PUF (SPUF) by exploiting strain-induced reversible cracking in the contact microstructures of graphene field-effect transistors (GFETs). We found that strain cycling in GFETs with a piezoelectric gate stack and high-tensile-strength metal contacts can lead to an abrupt transition in some GFET transfer characteristics, whereas other GFETs remain resilient to strain cycling. Strain sensitive GFETs show colossal ON/OFF current ratios >107, whereas strain-resilient GFETs show ON/OFF current ratios <10. We fabricated a total of 25 SPUFs, each comprising 16 GFETs, and found near-ideal performance. SPUFs also demonstrated resilience to regression-based machine learning (ML) attacks in addition to supply voltage and temporal stability. Our findings highlight the opportunities for emerging straintronic devices in addressing some of the critical needs of the microelectronics industry.

5.
J Glob Infect Dis ; 14(2): 57-63, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35910822

RESUMO

Introduction: Co-infection with different agents such as bacterial, viral, and Rickettsia is being increasingly recognized due to greater availability and utilization of the diagnostic tests among malaria patients. Methods: Consecutive admitted malarial cases were included and were subjected to test for general investigations, bacteria, typhoid, dengue, chikungunya, and rest for specific diagnosis. All patients were followed up till discharge or death and appropriate statistical tests were performed. Results: A total of 152 malaria patients were recruited and 27 (18.8%) had concurrent infections. It included 40.7% dengue only, 18.7% pneumonia, 11.1% urinary tract infection (UTI), 7.4% enteric fever, 3.7% leptospirosis, chikungunya, and tuberculous meningitis each, and 3.7% each of dengue with pneumonia and UTI. The organisms isolated were Streptococcus pneumoniae, Klebsiella pneumoniae, Escherichia coli, Salmonella typhi, and Mycobacterium tuberculosis. The mean duration of fever was 6.33 ± 3.63 days with a range of 3-20 days. Blood culture grew in 2 cases S. typhi and K. pneumonia,e. Dengue co-infections had significantly higher clinical and laboratory features of dengue and complications such as bleeding, jaundice, and cholecystitis, whereas rest concurrent infections had a significantly higher proportion of nausea and vomiting, convulsion, altered sensorium, productive cough, urinary symptoms, shock, acute kidney injury, anemia, and mean neutrophil count. There was significantly higher mortality among malaria-dengue concurrent infection group with 2 (15.4%) than malaria mono-infection group 3 (2.4%). Conclusion: Co-infections with malaria are not uncommon, especially dengue fever and other bacterial infections. The dominant clinical picture is of the superimposed infection. Decision should be clinically guided adjunct with specific diagnostic tests, and timely treatment has favorable outcome.

6.
BMJ Open ; 12(6): e059540, 2022 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-35649613

RESUMO

OBJECTIVES: To determine whether hydroxychloroquine when used with personal protective equipment reduces the proportion of laboratory-confirmed COVID-19 among healthcare workers in comparison to the use of personal protective equipment alone. DESIGN: Multicentre, parallel-group, open-label randomised trial. Enrolment started on 29 June 2020 and stopped on 4 February 2021. Participants randomised in HydrOxychloroquine Prophylaxis Evaluation were followed for 6 months. SETTING: 9 hospitals across India. PARTICIPANTS: Healthcare workers in an environment with exposure to COVID-19 were randomised in a 1:1 ratio to hydroxychloroquine plus use of personal protective equipment or personal protective equipment alone. 886 participants were screened and 416 randomised (213 hydroxychloroquine arm and 203 personal protective equipment). INTERVENTION: Participants in intervention arm received 800 mg of hydroxychloroquine on day of randomisation and then 400 mg once a week for 12 weeks in addition to the use of personal protective equipment. In the control arm, participants continued to use personal protective equipment alone. MAIN OUTCOME: Proportion of laboratory-confirmed COVID-19 in the 6 months after randomisation. RESULTS: Participants were young (mean age 32.1 years, SD 9.1 years) with low-comorbid burden. 47.4% were female. In the 6 months after randomisation (primary analysis population=413), 11 participants assigned to the hydroxychloroquine group and 12 participants assigned to the standard practice group met the primary endpoint (5.2% vs 5.9%; OR 0.85, 95% CI 0.35 to 2.07, p=0.72). There was no heterogeneity of treatment effect in any prespecified subgroup. There were no significant differences in the secondary outcomes. The adverse event rates were 9.9% and 6.9% in the hydroxychloroquine and standard practice arms, respectively. There were no serious adverse events in either group. CONCLUSIONS AND RELEVANCE: Hydroxychloroquine along with personal protective equipment was not superior to personal protective equipment alone on the proportion of laboratory-confirmed COVID-19. Definitive conclusions are precluded as the trial stopped early for futility, and hence was underpowered. TRIAL REGISTRATION NUMBER: CTRI/2020/05/025067.


Assuntos
Tratamento Farmacológico da COVID-19 , COVID-19 , Equipamento de Proteção Individual , Adulto , COVID-19/prevenção & controle , Feminino , Pessoal de Saúde , Humanos , Hidroxicloroquina/uso terapêutico , Índia/epidemiologia , Masculino
7.
Indian J Otolaryngol Head Neck Surg ; 74(Suppl 3): 5739-5743, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36742572

RESUMO

Postoperative sore throat (POST) is the eighth most common side effect in the postoperative period. Though it is considered as a minor side effect, it can lead to significant discomfort for the patient. Increased morbidity due to postoperative sore throat could have a big impact on outcomes with an increased economic burden to the nation. To determine the efficacy of ketamine gargle on a postoperative sore throat, we compared ketamine gargle with a normal saline gargle. Furthermore, we studied their efficacy on postoperative cough and hoarseness of voice. We randomly allocated 60 patients of ASA-I and II into two groups equally in patients posted for middle ear surgeries under general anaesthesia. Patients of the group- K were asked to gargle with 40 mg ketamine mixed with 29 ml normal saline preoperatively. Group- C patients were given 30 ml normal saline to gargle. Airway manipulation in all patients was done by senior anesthesiologists in the operating room. Patients were observed and interviewed at 1 h, 6 h, and 24 h after extubation for postoperative sore throat, cough, and hoarseness of voice. In the control group, the incidence of postoperative sore throat at 1 h, 6 h, and 24 h was 50%, 43.3%, and 36.7% respectively. When we compared the incidence in the ketaminegroup (Group-K) with the control group it showed that they were significantly lower (p-value ≤ 0.05) at all three observation points. On the other hand, ketamine gargle has no significant protective effect on the severity of postoperative sore throat, cough, and hoarseness of voice. Ketamine gargle in this study, showed significantly effective in attenuating postoperative sore throat in patients undergoing tracheal intubation for elective surgeries.

8.
Indian J Tuberc ; 67(3): 378-382, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32825873

RESUMO

Pneumocytis jirovecii pneumonia (PJP) and Pulmonary TB (PTB) both are common opportunistic infections among HIV infected individuals. But concurrent infections pose a diagnostic challenge owing to similar clinical features. Data suggests a high prevalence of such concurrent infections in developing countries but limited diagnostic modalities especially in resource constraint setup limits accurate diagnosis. At our centre we came across 6 newly diagnosed PTB patients among HIV infected ones had persistent shortness of breath (SOB) and hypoxia despite starting anti-tuberculous treatment (ATT). We excluded concomitant bacterial pneumonia by imaging, sputum examination and blood culture. Serum lactate dehydrogenase (LDH) was estimated and hypoxia by arterial blood gas (ABG). We found all 6 patients had elevated serum LDH, hypoxia and imaging suggestive of PJP were offered sputum for Geisma stain and standard treatment for PJP in form of Bactrim-double strength and steroid. 1 patient had PJ cysts in sputum. 5 patient's classical radiologic findings in form of ground glass opacities in lower lobes along with bilateral infiltrates and 1 had honeycombing. Serum LDH was elevated all 6 subjects. 5 were newly diagnosed HIV and 4 had CD4 count below 50 cells/mm3 and 2 had below 200 cells/mm3.1 patient had developed bilateral pneumothorax as complication. 4 patients responded to treatment and 2 (33.3%) died of respiratory failure during treatment. We were able to diagnose only severe PJP cases as concurrent infection with PTB as there was no availability of broncho alveolar lavage (BAL) as well as direct fluorescent antigen (DFA) test for PJ detection. A high index of suspicion for PJP even in PTB patients with low CD4 count will guide to appropriate therapy for both infections and eventually reduces morbidity and mortality.


Assuntos
Infecções por HIV/diagnóstico , Pneumonia por Pneumocystis/diagnóstico , Tuberculose Pulmonar/diagnóstico , Adulto , Técnicas de Cultura , Dispneia/fisiopatologia , Infecções por HIV/complicações , Recursos em Saúde , Humanos , Hipóxia/fisiopatologia , Índia , Masculino , Pessoa de Meia-Idade , Pneumonia por Pneumocystis/complicações , Pneumonia por Pneumocystis/fisiopatologia , Pneumotórax/fisiopatologia , Radiografia Torácica , Tomografia Computadorizada por Raios X , Tuberculose Pulmonar/complicações , Tuberculose Pulmonar/fisiopatologia
9.
J Vector Borne Dis ; 57(3): 274-276, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-34472512

RESUMO

Hyperreactive malarial splenomegaly (HMS) is one of the important causes of massive splenomegaly in malaria endemic zones. It is thought to represent a dysfunctional immune response to recurrent malarial infection. It is usually reported due to physical symptoms of splenomegaly and hypersplenism and fever is classically absent. Concomitant malaria with HMS is a very rare finding in the Indian context. Here, we report a case of symptomatic falciparum malaria presented with fever, jaundice, massive splenomegaly and pancytopenia. Persistent massive splenomegaly led us to investigate thoroughly and finally diagnosed it as HMS with concomitant falciparum malaria. He received standard antimalarial treatment and 12 months of weekly chloroquine and completely recovered without any relapse or complications.


Assuntos
Antimaláricos , Malária Falciparum , Malária , Adolescente , Antimaláricos/uso terapêutico , Cloroquina/uso terapêutico , Humanos , Malária/tratamento farmacológico , Malária Falciparum/complicações , Malária Falciparum/diagnóstico , Malária Falciparum/tratamento farmacológico , Masculino , Esplenomegalia/diagnóstico , Esplenomegalia/tratamento farmacológico , Esplenomegalia/etiologia
10.
Phys Rev Lett ; 123(16): 164801, 2019 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-31702367

RESUMO

Motivated by recent interest in photon and electron vortex beams, we propose the construction of a relativistic anyon beam. Following Jackiw and Nair [R. Jackiw and V. P. Nair, Phys. Rev. D 43, 1933 (1991).PRVDAQ0556-282110.1103/PhysRevD.43.1933] we derive an explicit form of the relativistic plane wave solution of a single anyon. Subsequently we construct the planar anyon beam by superposing these solutions. Explicit expressions for the conserved anyon current are derived. Finally, we provide expressions for the anyon beam current using the superposed waves and discuss its properties. We also comment on the possibility of laboratory construction of an anyon beam.

11.
J Mech Behav Biomed Mater ; 100: 103412, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31487620

RESUMO

The incidence of total hip arthroplasty (THA) has been evidently growing over the last few decades. Surface modification, such as polymer grafting onto implant surfaces using poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC), has been gaining attention due to its excellent biocompatibility and high lubricity behaviour resulting in reducing surgical recurrence number and increasing implant lifetime. Investigating thermal stability and mechanical properties of the grafted polymer is, therefore, extremely important as these properties define the failure mechanism of implants. This study focuses on optimising monomer concentration to achieve the best physical, thermal and mechanical properties of the grafted additively manufactured titanium (Ti6Al4V) implants. Three different concentration of monomers, 0.4 M, 0.6 M and 0.8 M, were investigated, and grafted implants were characterised. The results from thermal analysis confirmed that the PMPC polymer is thermally stable for implant applications regardless of the monomer concentrations. A significant reduction in Young's modulus of polymer grafted samples (33.2-42.9%), in comparison with untreated Ti6Al4V samples and consequent improvement of wear resistance and elasticity behaviour, proved the potentiality of polymer films for implant applications. In summary, polymer grafted implant prepared with 0.6 M monomer concentration showed the optimal thermal, physical and wear resistance properties.


Assuntos
Artroplastia de Quadril/instrumentação , Prótese de Quadril , Metacrilatos/química , Fosforilcolina/análogos & derivados , Titânio/química , Ligas , Materiais Biocompatíveis/química , Varredura Diferencial de Calorimetria , Articulação do Quadril/fisiopatologia , Temperatura Alta , Humanos , Teste de Materiais , Fosforilcolina/química , Polietileno/química , Polímeros/química , Desenho de Prótese , Falha de Prótese , Estresse Mecânico , Propriedades de Superfície , Termogravimetria
12.
Mater Sci Eng C Mater Biol Appl ; 101: 696-706, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31029363

RESUMO

Despite the tremendous acceptance of additively manufactured (AM) Titanium alloys (Ti6Al4V) in the field of biomedical engineering, the high surface roughness due to partially-melted particles (fabricated in selective laser melting (SLM) process), limits their uses as hip implants. The objective of this study, therefore, is to modify the SLM fabricated Ti6Al4V implant interfaces with 2-Methacryloyloxyethyl phosphorylcholine (MPC) polymer, in the hope of enhancing surface properties and preventing the attachment of the cell simultaneously without affecting the mechanical properties significantly. Three different monomer concentrations were examined to determine the influence of monomer concentrations on polymerisation rate, chain length, and surface properties of the implants. Samples grafted with 0.6 M monomer concentration showed more uniform surface and less surface roughness in comparison with other samples and untreated Ti6Al4V surfaces. 0.6 M monomer concentration was found to be the best option for grafting PMPC to the hip implant interfaces because of its improved surface morphology, surface roughness, polymerisation rate, penetration depth and hardness results. Moreover, cell study on optimal surfaces revealed that PMPC grafted surfaces prevent the implant interfaces from uncontrollable cell attachment which is of utmost importance in smoothing the motion of the hip implant under cyclic loading. Overall, the PMPC grafting demonstrated the potentiality of its application on SLM Ti6Al4V substrate for improved hip arthroplasty performance.


Assuntos
Fosforilcolina/química , Polímeros/química , Titânio/química , Artroplastia de Quadril/métodos , Humanos , Metacrilatos/química , Fosforilcolina/análogos & derivados
13.
ACS Appl Bio Mater ; 2(12): 5905-5915, 2019 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-35021512

RESUMO

Polypropylene (PP) surgical mesh has attracted vast attention due to its chemical inertness and excellent mechanical properties. However, improvement is necessary to enhance its biocompatibility and to prevent unwanted tissue adhesion. This study addresses these issues through surface modification of plasma-activated PP mesh with a 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer. Reaction time and monomer concentration have been optimized to achieve the optimal biocompatibility with reduction in protein adsorption. Attenuated total reflection-Fourier transform infrared spectra confirmed the grafting of the MPC polymer (PMPC) to the plasma-activated polypropylene (PPP) mesh. Scanning electron microscopy images and energy-dispersive X-ray (EDX) line spectra exhibited morphological changes and specifically PMPC grafting to the surface of PPP mesh, due to the presence of a significant amount of phosphorus (P) on the grafted PPP mesh. PMPC-grafted polypropylene (PPP-PMPC) showed a significant reduction in contact angle as well as the amount of adsorbed bovine serum albumin (BSA) protein in comparison with pristine PP mesh. The highest reduction in protein adsorption and the lowest contact angle were achieved at the monomer concentration of 0.3 M and the reaction time of 90 min. A longer reaction time and higher monomer concentration resulted in clogging within the mesh pores. MTT assay results (∼90% cell viability) confirmed the nontoxicity of the PMPC-grafted mesh, while optical microscopic and SEM images showed increased resistance of cell attachment to the surface of PMPC-grafted mesh. The results show that PPP-PMPC can be a promising biomaterial to address the current issues in biocompatibility and reduction in adhesion after surgery.

14.
J Mech Behav Biomed Mater ; 87: 312-324, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30103113

RESUMO

A significant number of hip replacements (HR) fail permanently despite the success of the medical procedure, due to wear and progressive loss of osseointegration of implants. An ideal model should consist of materials with a high resistance to wear and with good biocompatibility. This study aims to develop a new method of grafting the surface of selective laser melted (SLM) titanium alloy (Ti-6Al-4V) with poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC), to improve the surface properties and biocompatibility of the implant. PMPC was grafted onto the SLM fabricated Ti-6Al-4V, applying the following three techniques; ultraviolet (UV) irradiation, thermal heating both under normal atmosphere and UV irradiation under N2 gas atmosphere. Scanning electron microscopy (SEM), 3D optical profiler, energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) were used to characterise the grafted surface. Results demonstrated that a continuous PMPC layer on the Ti-6Al-4V surface was achieved using the UV irradiation under N2 gas atmosphere technique, due to the elimination of oxygen from the system. As indicated in the results, one of the advantages of this technique is the presence of phosphorylcholine, mostly on the surface, which reveals the existence of a strong chemical bond between the grafted layer (PMPC) and substrate (Ti-6Al-4V). The nano-scratch test revealed that the PMPC grafted surface improves the mechanical strength of the surface and thus, protects the underlying implant substrate from scratching under high loads.


Assuntos
Prótese de Quadril , Lasers , Fosforilcolina/análogos & derivados , Ácidos Polimetacrílicos/química , Titânio/química , Adesividade , Adsorção , Ligas , Osseointegração/efeitos dos fármacos , Transição de Fase , Fosforilcolina/química , Fosforilcolina/farmacologia , Ácidos Polimetacrílicos/farmacologia , Albumina Sérica/química , Molhabilidade
15.
Appl Opt ; 56(27): 7525-7532, 2017 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-29047727

RESUMO

The DC magnetron sputter grown Co/Ti multilayers, with ultra-low bi-layer thicknesses and with Co layers deposited under mixed ambience of argon and dry air, have been investigated for use in the water window soft x-ray regime of 23-44 Å. Initially, deposition parameters have been optimized for obtaining smooth and continuous low thickness Co and Ti single-layer films, and, then, multilayers with five bi-layers of various bi-layer thicknesses were deposited. The samples have been primarily characterized by the grazing incidence x-ray reflectivity (GIXR) measurements with a hard x-ray laboratory source. Subsequently, a set of multilayers with an increasing number of bi-layers has been deposited with a constant bi-layer thickness of 42 Å. GIXR results show that hard x-ray reflectivity at the first Bragg peak is maximum for the 20 bi-layer sample, beyond which the reflectivity decreases. Finally, the samples with the most promising hard x-ray GIXR have been used for soft x-ray reflectivity measurement with synchrotron radiation, and ∼2.5% peak reflectivity has been obtained in the multilayer sample at a 30.7 Å wavelength for a 21.5° grazing angle of incidence. The fitting results for both hard and soft x-ray reflectivities have been thoroughly investigated to find out the cause of the saturation of reflectivity with the increase in the number of bi-layers.

16.
J Neurosci Methods ; 284: 71-84, 2017 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-28396177

RESUMO

BACKGROUND: While many groups use experimental autoimmune encephalomyelitis (EAE) as a model to uncover therapeutic targets and understand the pathology underlying multiple sclerosis (MS), EAE protocol variability introduces discrepancies in central nervous system (CNS) pathogenesis and clinical disease, limiting the comparability between studies and slowing much-needed translational research. OPTIMIZED METHOD: Here we describe a detailed, reliable protocol for chronic EAE induction in C57BL/6 mice utilizing two injections of myelin oligodendrocyte glycoprotein (35-55) peptide mixed with complete Freund's adjuvant and paired with pertussis toxin. RESULTS: The active MOG35-55-EAE protocol presented here induces ascending paralysis in 80-100% of immunized mice. We observe: (1) consistent T cell immune activation, (2) robust CNS infiltration by peripheral immune cells, and (3) perivascular demyelinating lesions concurrent with axon damage in the spinal cord and various brain regions, including the optic nerve, cortex, hippocampus, internal capsule, and cerebellum. COMPARISON WITH EXISTING METHOD(S): Lack of detailed protocols, combined with variability between laboratories, make EAE results difficult to compare and hinder the use of this model for therapeutic development. We provide the most detailed active MOG35-55-EAE protocol to date. With this protocol, we observe high disease incidence and a consistent, reliable disease course. The resulting pathology is MS-like and includes optic neuritis, perivascular mononuclear infiltration, CNS axon demyelination, and axon damage in both infiltrating lesions and otherwise normal-appearing white matter. CONCLUSIONS: By providing a detailed active MOG35-55-EAE protocol that yields consistent and robust pathology, we aim to foster comparability between pre-clinical studies and facilitate the discovery of MS therapeutics.


Assuntos
Modelos Animais de Doenças , Encefalomielite Autoimune Experimental/imunologia , Encefalomielite Autoimune Experimental/patologia , Adjuvante de Freund , Esclerose Múltipla/imunologia , Esclerose Múltipla/patologia , Glicoproteína Mielina-Oligodendrócito , Animais , Combinação de Medicamentos , Encefalomielite Autoimune Experimental/induzido quimicamente , Feminino , Humanos , Estudos Longitudinais , Camundongos , Camundongos Endogâmicos C57BL , Esclerose Múltipla/induzido quimicamente , Fragmentos de Peptídeos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Resultado do Tratamento
17.
Sci Technol Adv Mater ; 17(1): 715-735, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28228866

RESUMO

Surface modification techniques have been developed significantly in the last couple of decades for enhanced tribological performance of artificial hip implants. Surface modification techniques improve biological, chemical and mechanical properties of implant surfaces. Some of the most effective techniques, namely surface texturing, surface coating, and surface grafting, are applied to reduce the friction and wear of artificial implants. This article reviews the status of the developments of surface modification techniques and their effects on commonly used artificial joint implants. This study focused only on artificial hip joint prostheses research of the last 10 years. A total of 27 articles were critically reviewed and categorized according to surface modification technique. The literature reveals that modified surfaces exhibit reduced friction and enhanced wear resistance of the contact surfaces. However, the wear rates are still noticeable in case of surface texturing and surface coating. The associated vortex flow aids to release entrapped wear debris and thus increase the wear particles generation in case of textured surfaces. The earlier delamination of coating materials due to poor adhesion and graphitization transformation has limited the use of coating techniques. Moreover, the produced wear debris has adverse effects on biological fluid. Conversely, the surface grafting technique provides phospholipid like layer that exhibited lower friction and almost zero wear rates even after a longer period of friction and wear test. The findings suggest that further investigations are required to identify the role of surface grafting on film formation and heat resistance ability under physiological hip joint conditions for improved performance and longevity of hip implants.

18.
Sci Technol Adv Mater ; 16(3): 035002, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27877803

RESUMO

Osteoarthritis-oriented synovial fluid (OASF), i.e., that typical of a patient with osteoarthritis, has different physical and biological characteristics than bovine serum (BS), a lubricant widely used in biotribological investigations. Micro-dimpled and diamond-like carbon- (DLC) coated surfaces are key emerging interfaces for orthopedic implants. In this study, tribological performances of dimpled surfaces, with and without DLC coating, have been investigated under both BS and OASF. The friction tests were performed utilizing a pin on a disk tribometer, whereas contact pressure, speed, and temperature were simulated to a 'medium walking gait' of hip joint conditions. The mechanical properties of the specimen and the physical properties of the lubricant were characterized before the friction test. Raman analysis was conducted to identify the coating condition both before and after the test. The DLC-coated dimpled surface showed maximum hardness and residual stress. A DLC-coated dimpled surface under an OASF lubricated condition yielded a lower friction coefficient and wear compared to those of plain and dimpled specimens. The higher graphitization of coated materials with increasing load was confirmed by Raman spectroscopy.

19.
Sci Technol Adv Mater ; 16(4): 045002, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27877822

RESUMO

The concentration of biological components of synovial fluid (such as albumin, globulin, hyaluronic acid, and lubricin) varies between healthy persons and osteoarthritis (OA) patients. The aim of the present study is to compare the effects of such variation on tribological performance in a simulated hip joint model. The study was carried out experimentally by utilizing a pin-on-disk simulator on ceramic-on-ceramic (CoC) and ceramic-on-polyethylene (CoP) hip joint implants. The experimental results show that both friction and wear of artificial joints fluctuate with the concentration level of biological components. Moreover, the performance also varies between material combinations. Wear debris sizes and shapes produced by ceramic and polyethylene were diverse. We conclude that the biological components of synovial fluid and their concentrations should be considered in order to select an artificial hip joint to best suit that patient.

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