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1.
Cureus ; 16(7): e65823, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-39228896

RESUMO

Carpal tunnel syndrome (CTS) is the most prevalent focal mononeuropathy worldwide and is traditionally diagnosed based on clinical history, examination, and nerve conduction studies. Surgical release is the gold standard in cases where conservative management fails; however, it is prudent to obtain imaging before planning such intervention. We present the case of a 47-year-old woman who presented with typical symptoms of CTS, which was confirmed with nerve conduction studies and was being considered for carpal tunnel release surgery. Her history and laboratory studies revealed rheumatoid arthritis and subsequent ultrasonography showed swelling of the median nerve just proximal to the transverse carpal ligament at the level of pronator quadratus muscle. The possibility of a nerve sheath tumour or tenosynovitis with edematous fascicles of the median nerve was considered, and a decision was taken to give a short course of prednisolone 1 mg/kg, to which she clinically responded and the repeat ultrasonography showed near complete resolution of the focal nerve enlargement. This case emphasizes the role of point-of-care neuromuscular ultrasound (NMUS) in identifying the underlying cause of CTS and validates NMUS as a powerful tool in reaching a comprehensive diagnosis in entrapment neuropathies and it should be incorporated into the routine protocol of diagnosis of these disorders.

2.
J Phys Chem B ; 128(32): 7736-7749, 2024 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-39088441

RESUMO

Membrane-peptide interactions are key to the formation of helical intermediates in the early stages of amyloidogenesis. Aqueous solutions of 2,2,2-trifluoroethanol (TFE) provide a membrane-mimetic environment capable of promoting and stabilizing local peptide interactions. Uperin 3.5 (U3.5), a 17-residue and amidated antimicrobial peptide, is unstructured in water but self-assembles into fibrils in the presence of salt. Secondary structure transitions linked to U3.5 self-assembly were investigated in TFE/water mixtures, in both the absence and presence of salt, to assess the role of membrane-peptide interactions on peptide self-assembly and amyloid formation. A 5-to-7-fold increase in fibril yield of U3.5 was observed at low TFE concentrations (10% TFE/water v/v) compared with physiological buffer but only in the presence of salt. No aggregation was observed in salt-free TFE/water mixtures. Circular dichroism spectra showed that partial helical structures, initially stabilized by TFE, transitioned to ß-sheet-rich aggregates in a saline buffer. Molecular dynamics simulations confirmed that TFE and salt act synergistically to enhance peptide-peptide interactions, resulting in ß-sheet-rich U3.5 oligomers at low TFE concentrations. Specifically, TFE stabilized amphipathic, helical intermediates, leading to increased peptide-peptide attraction through hydrophobic interactions. The presence of salt further enhanced the peptide-peptide interactions by screening positively charged residues. Thus, the study revealed the role of a membrane mimic in stabilizing helical intermediates on the pathway to amyloid formation in the antimicrobial U3.5 peptide.


Assuntos
Estrutura Secundária de Proteína , Trifluoretanol , Água , Trifluoretanol/química , Água/química , Dicroísmo Circular , Peptídeos/química , Simulação de Dinâmica Molecular
3.
Phys Chem Chem Phys ; 25(48): 32824-32836, 2023 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-38018404

RESUMO

The role of hydrophobicity of phenylalanine-glycine nucleoporins (FG-Nups) in determining the transport of receptor-bound cargo across the nuclear pore complex (NPC) is investigated using Langevin dynamics simulations. A coarse-grained, minimal model of the NPC, comprising a cylindrical pore and hydrophobic-hydrophilic random copolymers for FG-Nups was employed. Karyopherin-bound receptor-cargo complexes (Kaps) were modeled as rigid, coarse-grained spheres without (inert) and with (patchy) FG-binding hydrophobic domains. With a sequence-agnostic description of FG-Nups and the absence of any anisotropies associated with either NPC or cargo, the model described tracer transport only as a function of FG-Nup hydrophobicity, f. The simulations showed the emergence of two important features of cargo transport, namely, NPC selectivity and specificity. NPC selectivity to patchy tracers emerged due to hydrophobic Kap-FG interactions and despite the sequence-agnostic description of FG-Nups. Furthermore, NPC selectivity was observed only in a specific range of FG-hydrophobic fraction, 0.05 ≤ f ≤ 0.20, resulting in specificity of NPC transport with respect to f. Significantly, this range corresponded to the number fraction of FG-repeats observed in both S. cerevisiae and H. sapiens NPCs. This established the central role of the FG-hydrophobic fraction in determining NPC transport, and provided a biophysical basis for conservation of the FG-Nup hydrophobic fraction across evolutionarily distant NPCs. Specificity in NPC transport emerged from the formation of a hydrogel-like network inside the pore with a characteristic mesh size dependent on f. This network rejected cargo for f > 0.2 based on size exclusion, which resulted in enhanced translocation probability for 0.05 ≤ f ≤ 0.20. Extended brush configurations outside the pore resulted in entropic repulsion and exclusion of inert cargo in this range. Thus, our minimal NPC model exhibited a hybrid cargo translocation mechanism, with aspects of both virtual gate and selective-phase models, in this range of FG-hydrophobic fraction.


Assuntos
Poro Nuclear , Saccharomyces cerevisiae , Poro Nuclear/química , Complexo de Proteínas Formadoras de Poros Nucleares/análise , Complexo de Proteínas Formadoras de Poros Nucleares/química , Glicina/química , Fenilalanina/química
4.
Phys Chem Chem Phys ; 25(17): 12134-12147, 2023 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-37070341

RESUMO

Helical intermediates appear to be crucial in the amyloid formation of several amyloidogenic peptides, including Aß, that are implicated in different neurodegenerative diseases. Intermediate species of amyloid formation have been reported to be more toxic than mature amyloid fibrils. Hence, the current work focuses on understanding the mechanistic roles of the helical intermediates in the early stages of amyloid self-assembly in amyloidogenic peptides. Molecular dynamics (MD) simulations and the adaptive biasing force (ABF) method were utilized to investigate structural changes that lead to amyloid formation in amphibian peptide uperin-3.5 (U3.5), an antimicrobial and amyloidogenic peptide. Microsecond time-scale MD simulations revealed that peptide aggregation, into ß-sheet dominated aggregates, is centred on two important factors; evolution of α-helical intermediates and the critical role of local peptide concentration inside these aggregates. Electrostatic attraction between the oppositely charged aspartate (D) and arginine (R) residues located near the N-terminus induced hydrogen bonding resulting in the formation of precursor 310-helices close to the N-terminus. The 310-helices transitioned into α-helices, thereby imparting partial helical conformations to the peptides. In the initial stages of aggregation, U3.5 peptides with amphipathic, partial helices were driven closer by hydrophobic interactions to form small clusters of helical intermediates. These helices imparted stability to the helical intermediates, which promoted the growth of clusters by further addition of peptides. This led to an increase in the local peptide concentration, which enabled stronger peptide-peptide interactions and triggered a ß-sheet transition in these aggregates. Thus, this study emphasized that the helical intermediates may be crucial to the evolution of ß-sheet-rich amyloid structures.


Assuntos
Amiloide , Peptídeos Antimicrobianos , Animais , Amiloide/química , Simulação de Dinâmica Molecular , Conformação Proteica em Folha beta , Anfíbios , Peptídeos beta-Amiloides/química
5.
MicroPubl Biol ; 20232023.
Artigo em Inglês | MEDLINE | ID: mdl-37008727

RESUMO

Mutations in TDP-43 are known to cause Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD). TDP-43 binds to and regulates splicing of several RNA including Zmynd11 . Zmynd11 is a transcriptional repressor and a potential E3 ubiquitin ligase family member, known for its role in neuron and muscle differentiation. Mutations in Zmynd11 have been associated with autism with significant developmental motor delays, intellectual disability, and ataxia. Here, we show that Zmynd11 is aberrantly spliced in the brain and spinal cord of transgenic mice overexpressing a mutant human TDP-43 (A315T), and that these changes occur before the onset of motor symptoms.

6.
Chempluschem ; 87(1): e202100408, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-35032115

RESUMO

Secondary structure changes are an inherent part of antimicrobial (AMP) and amyloidogenic peptide activity, especially in close proximity to membranes, and impact the peptides' function and dysfunction roles. The formation, and stability of α-helical components are regarded as essential 'intermediates' for both these functions. To illuminate the conformational transitions leading to amyloid formation we use short cationic AMPs, from an Australian toadlet, Uperoleia mjobergii, (Uperin 3 family, U3) and assess the impact on secondary structural elements in the presence of a membrane mimetic surfactant, sodium dodecyl sulfate (SDS). Specifically, Uperin 3.x, where x=4, 5, 6 wild-type peptides and position seven variants for each, R7A or K7A, were investigated using a combination of experimental and simulation approaches. In water, U3 peptides remain largely unstructured as random coils, with the addition of salts initiating structural transitions leading to assembly towards amyloid. Solution NMR data show that an unstructured U3.5 wt peptide transitions in the presence of SDS to a well-defined α-helical structure that spans nearly the entire sequence. Circular dichroism (CD) and ThT fluorescence studies show that all six U3 peptides aggregate in solution, albeit with vastly varying rates, and a dynamic equilibrium between soluble aggregates rich in either α-helices or ß-sheets may exist in solution. However, the addition of SDS leads to a rapid disaggregation for all peptides and stabilisation of predominantly α-helical content in all the U3 peptides. Molecular dynamics (MD) simulations show that the adsorption of U3.5 wt/R7A peptides onto the SDS micelle is driven by Coulombic attraction between peptide cationic residues and the negatively charged sulfate head-groups on SDS. Simulating the interactions of various kinds of ß-sheet dimers (of both U3.5 wt and its variant U3.5 R7A) with SDS micelles confirmed ß-sheet content decreases in the dimers after their attachment to the SDS micelle. Adsorbed peptides interact favourably with the hydrophobic core of the micelle, promoting intramolecular hydrogen bonds leading to stabilisation of the α-helical structure in peptides, and resulting in a corresponding decrease in intermolecular hydrogen bonds responsible for ß-sheets.


Assuntos
Anti-Infecciosos , Peptídeos Antimicrobianos , Austrália , Peptídeos , Dodecilsulfato de Sódio
7.
J Neurosci Rural Pract ; 12(3): 550-554, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34434030

RESUMO

Background There is an apparently high incidence of stroke mimics in the present-day stroke code era. The reason being is the intense pressure to run with time to achieve the "time is brain"-based goals. Methods The present study was a retrospective analysis of the data collected over a duration of 6 months from April 2019 to September 2019. We observed the incidence of stroke mimics among the patients for whom rapid response stroke code was activated during the study period. We also performed a logistic regression analysis to identify the clinical features which can act as strong predictors of stroke and mimics. Results A total of 314 stroke codes were activated of which 256 (81.5%) were stroke and 58 (18.5%) were the mimics. Functional disorders and epilepsy were the most common mimics (24.1% each). Female gender ( p = 0.04; odds ratio [OR] 2.9[1.0-8.8]), isolated impairment of consciousness ( p < 0.01; OR 4.3[1.5-12.6]), and isolated dysarthria ( p < 0.001) were the strong independent predictors for a stroke mimic. Hemiparesis was the strong independent predictor for a stroke ( p < 0.001; OR 0.0[0.0-0.1]). Conclusion In the present epoch of rapid response stroke management, a streamlined assessment by the emergency physicians based on the above clinical predictors may help in avoiding the misdiagnosis of a mimic as stroke.

8.
Neurointervention ; 16(1): 78-82, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33460536

RESUMO

A 34-year-old post-partum female having dermatomyositis developed headache and became comatose after a seizure episode. Magnetic resonance imaging of brain showed a massive left ganglio-capsular bleed for which decompressive surgery was done. Computed tomographic angiography showed multiple foci of narrowing and irregularities in distal cerebral vessels. In view of dermatomyositis, the diagnosis of vasculitis was considered and pulse therapy of intravenous methylprednisolone was started. The patient, however, showed no improvement and developed new brain infarcts. She was subsequently taken up for a diagnostic cerebral angiography which showed multifocal severe narrowing in bilateral major cerebral arteries. These angiographic abnormalities showed excellent reversibility to intra-arterial milrinone and hence, reversible cerebral vasoconstriction syndrome (RCVS) was diagnosed. Normal angiographic findings in the first week do not rule out the disease and a repeat angiography should be considered if the clinical suspicion of the RCVS is high. Intra-arterial milrinone has a high diagnostic utility.

9.
J Phys Chem B ; 124(51): 11659-11670, 2020 12 24.
Artigo em Inglês | MEDLINE | ID: mdl-33322900

RESUMO

Antimicrobial peptides of the uperin 3.x family, obtained from the skin secretions of Uperoleia mjobergii, have an inherent ability to form amyloid with possible functional roles and can serve as model peptides to understand mechanistic aspects of amyloidogenesis. The substitution of a positively charged amino acid with a nonpolar alanine residue increased aggregation, fibril content, and propensity for ß-sheet formation for the uperin 3.5 R7A variant when compared with the uperin 3.5 wild-type peptides. We use molecular dynamics (MD) simulations and circular dichroism (CD) measurements on three uperin 3.x peptides and their corresponding seventh position alanine variants to understand the effect of substitution of a positively charged amino acid with a nonpolar alanine residue on the process of ß-aggregation. Both CD experiments and simulations show that the uperin 3.x wild-type peptides demonstrated lower ß-sheet content and propensity than with the corresponding alanine variants. Significantly, simulations of helix-to-coil transitions in individual peptides show an inverse relationship between the helical stability of peptides and their propensity to form structures rich in ß-sheets as observed in CD experiments. A simulation scheme based on a conformational search of helix-to-coil transition trajectories to select peptide conformers was used to assemble propagating peptide oligomers. Whereas octamers consisting of lower helical stability peptide conformers evolve into compact aggregates with a large ß-sheet component, octamers composed of high helical stability conformers disintegrate and show the least amounts of ß-sheet components. The highlight of the current work is that MD simulations are able to predict the correct order of ß-sheet propensity among the six peptides derived from the CD experiments and indicate the importance of helical intermediates in the amyloidogenesis pathway for uperin 3.x peptides.


Assuntos
Amiloide , Peptídeos Catiônicos Antimicrobianos , Dicroísmo Circular , Conformação Proteica em Folha beta , Estrutura Secundária de Proteína
10.
ACS Appl Mater Interfaces ; 12(5): 6581-6589, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31910617

RESUMO

In this work, controlled bidirectional deformation of suspended nanostructures by site-specific ion irradiation is presented. Multiscale modeling of the bidirectional deformation of nanostructures by site-specific ion irradiation is presented, incorporating molecular dynamics (MD) simulations together with finite element analysis, to substantiate the bending mechanism. Strain engineering of the free-standing nanostructure is employed for controlled deformation through site-specific kiloelectronvolt ion irradiation experimentally using a focused ion beam. We report the detailed bending mechanism of suspended silicon (Si) nanostructures through ion-induced irradiations. MD simulations are presented to understand the ion-solid interactions, defects formation in the silicon nanowire. The atomic-scale simulations reveal that the ion irradiation-induced bidirectional bending occurs through the development of localized tensile-compressive stresses in the lattice due to defect formation associated with atomic displacements. With an increasing ion dose, the evolution of localized tensile to compressive stress is observed, developing the alternate bending directions calculated through finite element analysis. The findings of multiscale modeling are in excellent agreement with the bidirectional nature of bending observed through the experiments. The developed in situ approach for bidirectional controlled manipulation of nanostructures in this work can be used for nanofabrication of numerous novel three-dimensional configurations and can provide a route toward functional nanostructures and devices.

11.
J Neurosci Rural Pract ; 10(3): 506-510, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31602156

RESUMO

Background Anterior tarsal tunnel syndrome (ATTS) is an uncommon entrapment neuropathy which occurs due to the compression of deep peroneal nerve under the inferior extensor retinaculum at the ankle. We observed a frequent occurrence of this syndrome in toddy palm tappers and hence, planned to study the association between the two. Materials and Methods We studied the prevalence of isolated deep peroneal neuropathy at the ankle among the asymptomatic toddy tappers enrolled over a period of 3 months. Results In our case series, 81% (17/21) of the study participants had ATTS of which 43% (9/21) had unilateral and 38% (8/21) had bilateral involvement. There was a strong inverse association (p < 0.001) of "duration of toddy tapping in years" with peroneal (extensor digitorum brevis) amplitudes on both the sides. Conclusion Our study confirms "palm tree climbing" to be an occupational etiology of ATTS.

12.
Nanotechnology ; 30(38): 385204, 2019 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-31048572

RESUMO

In bulk heterojunction organic solar cells (OSCs), nanomorphology of the photoactive layer plays a crucial role in determining photocurrent and fill factor (FF) of OSCs, and therefore it is essential to control the nanomorphology of the photoactive layer to fabricate devices with high power conversion efficiency (PCE). We demonstrate the combined effects of a ZnO nanorippled electron transport layer (ETL) and solvent additive (1,8-diiodooctane (DIO)) on the nanomorphology and performance of a model OSC in an inverted geometry. The photoactive layer in the model OSC is composed of Poly [4,8-bis (5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl] (PTB7-Th):phenyl-C71-butyric acid methyl ester (PC71BM) blend. It is observed that the use of ZnO nanoripples as an ETL and DIO as a solvent additive facilitates the formation of near ideal nanomorphology of bi-continuous interpenetrating network of donor and acceptor. This is confirmed by morphological studies using atomic force microscopy, scanning electron microscopy and transmission electron microscopy. Photo-electrochemical impedance spectroscopy measurements confirm that obtained nanomorphology of bicontinuous interpenetrating network is contributing to the improved device performance. The device with 3 vol% DIO, with underneath ZnO nanoripples exhibited improved current density (J sc), FF, open circuit voltage (V oc) and PCE of 15.57 mA cm-2, 64.50%, 0.81V and 8.20%, respectively.

13.
Ann Afr Med ; 17(2): 90-93, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29536964

RESUMO

OBJECTIVE: Outcome assessment of intravenous (IV) thrombolysis with tenecteplase in acute ischemic stroke. MATERIALS AND METHODS: We consecutively enrolled acute ischemic stroke patients who underwent IV thrombolysis with tenecteplase from October 2016 to May 2017. Primary clinical efficacy outcome was defined as an improvement in the National Institute of Health Stroke Scale (NIHSS) score of ≥4 points at 24 h (h). Secondary clinical efficacy outcome was the favorable outcome on modified Rankin scale at 90 days defined as a score of 0 or 1. The safety endpoints were death rate at 90 days and symptomatic intracranial hemorrhage (SICH). RESULTS: Mean NIHSS scores at baseline and 24 h were 13 (±3.81) and 9.29 (±5.74), respectively, the difference being statistically significant (P = 0.016). In this study, nine patients (64%) met the primary clinical efficacy outcome and eleven (78.5%) patients met the secondary clinical efficacy outcome. Only 1 (7%) patient developed SICH and additionally, aspiration pneumonia with subsequent death. CONCLUSION: This study confirms the efficacy and safety of tenecteplase for stroke thrombolysis in our clinical setting. Tenecteplase appears to be a suitable option for stroke thrombolysis in resource-limited settings, considering its cost-effectiveness, and ease of administration.


Objectif: Évaluation de la thrombolyse intraveineuse (IV) par la tenecteplase lors d'un AVC ischémique aigu. Matériel et Méthodes: Nous avons inclus consécutivement les patients AVC ischémiques ayant subi une thrombolyse intraveineuse avec tenecteplase d'octobre 2016 à mai 2017. Le critère d'efficacité clinique primaire a été défini comme une amélioration du score NIHSS (National Institute of Health Stroke Scale) de 24 h (h). Le résultat d'efficacité clinique secondaire était le résultat favorable sur l'échelle de Rankin modifiée à 90 jours définie comme un score de 0 ou 1. Les critères de tolérance étaient le taux de mortalité à 90 jours et l'hémorragie intracrânienne symptomatique (SICH). Résultats: Les scores NIHSS moyens au départ et 24 h étaient respectivement de 13 (± 3,81) et de 9,29 (± 5,74), la différence étant statistiquement significative (P = 0,016). Dans cette étude, neuf patients (64%) ont atteint le critère principal d'efficacité clinique et onze patients (78,5%) ont atteint le critère d'efficacité clinique secondaire. Seulement 1 patient (7%) a développé un SICH et, en outre, une pneumonie d'aspiration avec décès ultérieur. Conclusion: Cette étude confirme l'efficacité et l'innocuité de la tenecteplase pour la thrombolyse par AVC dans notre contexte clinique. La ténectéplase semble être une option appropriée pour la thrombolyse d'accident vasculaire cérébral dans les milieux à ressources limitées, compte tenu de son rapport coût-efficacité et de sa facilité d'administration. Mots-clés: AVC ischémique aigu, alteplase, tenecteplase, thrombolyse.


Assuntos
Isquemia Encefálica/tratamento farmacológico , Fibrinolíticos/uso terapêutico , Acidente Vascular Cerebral/tratamento farmacológico , Terapia Trombolítica , Ativador de Plasminogênio Tecidual/uso terapêutico , Administração Intravenosa , Feminino , Fibrinolíticos/administração & dosagem , Humanos , Índia , Masculino , Avaliação de Resultados em Cuidados de Saúde , Acidente Vascular Cerebral/complicações , Tenecteplase , Ativador de Plasminogênio Tecidual/administração & dosagem , Resultado do Tratamento
14.
Clin Rheumatol ; 37(5): 1367-1374, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-28842760

RESUMO

Vitamin D is vital for musculoskeletal health and may be associated with subacute and chronic low back pain. The objective of this study was to estimate the prevalence of vitamin D deficiency among chronic low back pain (CLBP) and subacute low back pain (SLBP), and compare the same with healthy controls. This study was designed as triple-arm case-control study comprising of CLBP, SLBP, and controls. SLBP and CLBP cases were consecutively enrolled over 3 months of winter season from November 2016 to January 2017. Serum 25- (OH) vitamin D was estimated for the study subjects and categorical comparison of severity of vitamin D deficiency was done for the cases and controls. A total of 250 CLBP, 177 SLBP cases, and 248 controls were included in the study. Mean (± SD) serum vitamin D levels among CLBP, SLBP, and controls were 20.36 (± 12.56), 21.42 (± 13.20), and 20.84 (± 6.93) ng/ml respectively, the difference being statistically insignificant. There was no significant difference in the prevalence of vitamin D deficiency among CLBP, SLBP, and controls which was 53.6, 50.8, and 51.6% respectively, in the three arms. However, the categorical analysis revealed that CLBP and SLBP cases had a significantly higher prevalence of worse categories of vitamin D deficiency. Cases had significantly larger frequency (CLBP vs. controls, 43.6 vs 20.1%, P<0.001; SLBP vs. controls, 43.5 vs 20.1%, P = 0.001) of individuals with vitamin D levels ≤ 16 ng/ml (moderate deficiency upper threshold level). Thus, the severe forms of vitamin D deficiency may be causally associated with CLBP and SLBP. The results of the present study revealed that increasing severity of vitamin D deficiency may have a pathogenetic association with chronic low back pain and subacute low back pain. These results may prove to be of significance in framing of future management guidelines for the above clinical conditions.


Assuntos
Dor Lombar/epidemiologia , Deficiência de Vitamina D/epidemiologia , Vitamina D/sangue , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Comorbidade , Feminino , Humanos , Índia/epidemiologia , Dor Lombar/sangue , Masculino , Pessoa de Meia-Idade , Medição da Dor , Prevalência , Estudos Prospectivos , Índice de Gravidade de Doença , Deficiência de Vitamina D/sangue , Adulto Jovem
15.
Phys Chem Chem Phys ; 19(44): 30217-30226, 2017 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-29109984

RESUMO

The effect of curvature and relative orientation between two curved graphene sheets in aqueous media is quantified by calculating the potential of mean force using molecular dynamics simulations and thermodynamic perturbation. The potential of mean force between two curved graphene sheets is found to scale as UCG ∼ R0.5d-4.5, where R is the sheet radius of curvature and d is the inter-sheet distance. Further, a simple analytical calculation based on classical Hamaker theory and the Derjaguin approximation also arrives at the same scaling of interaction energy with respect to R and d. For the case where a misorientation, θ, exists between the two curved graphene sheets, the simulation results strongly suggest an inverse dependence of the potential of mean force on sin θ for θ > 30°. This result is very similar to the scaling predicted by the Derjaguin approximation for two cylinders crossed at an angle θ with respect to each other.

16.
J Stroke Cerebrovasc Dis ; 26(11): 2563-2569, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28684377

RESUMO

BACKGROUND: The intracerebral hemorrhage (ICH) score is well established as a reliable prognostic score in ICH, whereas recently, Acute Physiology and Chronic Health Evaluation II (APACHE II) has been observed to have a better discrimination in predicting mortality in primary pontine hemorrhage. Further, physiological parameters of APACHE II have been associated with outcome in ICH. This study is the first to observe a direct comparison between APACHE II and ICH scores in predicting 30-day mortality in spontaneous intracerebral hemorrhage (SICH). MATERIALS AND METHODS: This study was a prospective observational study where we compared the receiver operating characteristic (ROCs) of baseline ICH and APACHE II scores in patients with SICH for predicting 30-day mortality outcome. RESULTS: We observed that both APACHE II and ICH scores were good for predicting 30-day mortality with both having an area under the ROC curve of more than .8 (.831 [95% confidence interval {CI}, .740-.922; P <.001] and .892 [95% CI, .757-.932; P <.001], respectively). However, the ICH score was better discriminative (area under the curve AUC, .892 versus .831; P = .040) and better calibrated (P = .037 versus P = .089, Hosmer-Lemeshow goodness-of-fit test for logistic regression) for the same. Both APACHE II and ICH scores had a sensitivity of 87% at cutoff values of 19 and 3, respectively; however, the ICH score had a better specificity (90% versus 76.5%). CONCLUSION: The ICH score was observed to have a better discrimination and calibration for predicting 30-day mortality in SICH.


Assuntos
Hemorragia Cerebral/diagnóstico , Hemorragia Cerebral/mortalidade , Indicadores Básicos de Saúde , Encéfalo/diagnóstico por imagem , Hemorragia Cerebral/fisiopatologia , Hemorragia Cerebral/terapia , Feminino , Seguimentos , Escala de Coma de Glasgow , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Prognóstico , Curva ROC , Estudos Retrospectivos , Sensibilidade e Especificidade , Índice de Gravidade de Doença , Tomografia Computadorizada por Raios X
17.
Ann Afr Med ; 15(4): 200-203, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27853035

RESUMO

Moyamoya disease (MMD) is a rare neurovascular disorder which pathologically, is a chronic cerebrovasculopathy. It is characterized by stenosis of the internal carotid artery (ICA) and the main branches within the circle of Willis with consecutive development of collateral vessels. There are a few cases in the literature which have described movement disorders as a manifestation of MMD; however these have been uncommonly reported in cases of moyamoya syndrome (MMS). We present a 10-year-old boy with dystonia, myoclonus and encephalopathy like features. These features in association with moyamoya, are rarely described.


Assuntos
Encefalopatias/fisiopatologia , Estenose das Carótidas/fisiopatologia , Distonia/fisiopatologia , Doença de Moyamoya/fisiopatologia , Mioclonia/fisiopatologia , Encefalopatias/etiologia , Estenose das Carótidas/complicações , Estenose das Carótidas/diagnóstico por imagem , Angiografia Cerebral , Criança , Distonia/etiologia , Humanos , Angiografia por Ressonância Magnética , Imageamento por Ressonância Magnética , Masculino , Doença de Moyamoya/complicações , Doença de Moyamoya/diagnóstico por imagem , Mioclonia/etiologia
18.
Artigo em Inglês | MEDLINE | ID: mdl-27679748

RESUMO

BACKGROUND: Hemichorea-hemiballism (HCHB) is a hyperkinetic movement disorder with features of both chorea and ballism occurring on the same side. CASE REPORT: We present a case of HCHB due to nonketotic hyperglycemia (NKH) that was the initial presentation of diabetes and was irreversible clinically even after 6 months of optimal blood sugar control. DISCUSSION: Although HCHB due to hyperglycemia is a potentially reversible condition in the majority of patients, prolonged uncontrolled hyperglycemia may cause ischemic insult and persistent symptoms. Hyperglycemia should always be kept in the list of differentials while dealing with patients who are newly diagnosed with HCHB.

19.
J Clin Diagn Res ; 10(6): OE01-9, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27504340

RESUMO

Metronidazole is an antimicrobial agent mainly used in the treatment of several protozoal and anaerobic infections, additionally, is often used in hepatic encephalopathy and Crohn disease. Apart from peripheral neuropathy, metronidazole can also cause symptoms of central nervous system dysfunction like ataxic gait, dysarthria, seizures, and encephalopathy which may result from both short term and chronic use of this drug and is collectively termed as "metronidazole induced encephalopathy"(MIE). Neuroimaging forms the backbone in clinching the diagnosis of this uncommon entity, especially in cases where there is high index of suspicion of intoxication. Although typical sites of involvement include cerebellum, brain stem and corpus callosum, however, lesions of other sites have also been reported. Once diagnosed, resolution of findings on Magnetic Resonance Imaging (MRI) of the Brain along with clinical improvement remains the mainstay of monitoring. Here we review the key clinical features and MRI findings of MIE as reported in medical literature. We also analyze implication of use of this drug in special situations like hepatic encephalopathy and brain abscess and discuss our experience regarding this entity.

20.
J Clin Diagn Res ; 10(5): OC44-7, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27437271

RESUMO

INTRODUCTION: Diabetes mellitus is a disease with a rapidly increasing prevalence, needs continue research for novel methods to both prevent and treat this disorder. Obesity and decreased physical activity are the major risk factor for the development of diabetes. Recently the emphasis is focused on oxidative stress in pathogenesis of this disease. AIM: To assess the serum levels of Nitric Oxide (NO) among diabetic patients and its correlation with lipid profile as well as oxidative stress in north Indian setting. MATERIALS AND METHODS: This was a cross-sectional study. Subjects suffering from type 2 diabetes for more than 1 year and age between 30 to 50 years with hyperuricaemia were included in the study. The patients were divided into three groups: Group I- Type 2 diabetics with dyslipidemia and hyperuricaemia, Group II- Type 2 diabetics with dyslipidemia and normouricaemia and Group III- Type 2 diabetics with normolipidemia and normouricaemia. RESULTS: The nitric oxide level was significantly lower in Group I and Group II than Group III. The oxidative stress parameters had poor correlation with NO level in all the groups. CONCLUSION: Our data suggests that there is definite role of Nitric Oxide (NO) in pathogenesis of type -2 diabetes mellitus with dyslipidemia and hyperuricaemia.

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