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1.
Nature ; 625(7995): 489-493, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38172641

RESUMEN

The quantum Hall effect is a prototypical realization of a topological state of matter. It emerges from a subtle interplay between topology, interactions and disorder1-9. The disorder enables the formation of localized states in the bulk that stabilize the quantum Hall states with respect to the magnetic field and carrier density3. Still, the details of the localized states and their contribution to transport remain beyond the reach of most experimental techniques10-31. Here we describe an extensive study of the bulk's heat conductance. Using a novel 'multiterminal' short device (on a scale of 10 µm), we separate the longitudinal thermal conductance, [Formula: see text] (owing to the bulk's contribution), from the topological transverse value [Formula: see text] by eliminating the contribution of the edge modes24. When the magnetic field is tuned away from the conductance plateau centre, the localized states in the bulk conduct heat efficiently ([Formula: see text]), whereas the bulk remains electrically insulating. Fractional states in the first excited Landau level, such as the [Formula: see text] and [Formula: see text], conduct heat throughout the plateau with a finite [Formula: see text]. We propose a theoretical model that identifies the localized states as the cause of the finite heat conductance, agreeing qualitatively with our experimental findings.

2.
Nano Lett ; 23(15): 6792-6798, 2023 Aug 09.
Artículo en Inglés | MEDLINE | ID: mdl-37477991

RESUMEN

In this Letter, we provide experimental evidence of the time-reversal symmetric Hall effect in a mesoscopic system, namely, high-mobility graphene-WSe2 heterostructures. This linear, dissipative Hall effect, whose sign depends on the sign of the charge carriers, persists up to room temperature. The magnitude and the sign of the Hall signal can be tuned using an external perpendicular electric field. Our joint experimental and theoretical study establishes that the strain induced by lattice mismatch, or alignment angle inhomogeneity, produces anisotropic bands in graphene while simultaneously breaking the inversion symmetry. The band anisotropy and reduced spatial symmetry lead to the appearance of a time-reversal symmetric Hall effect. Our study establishes graphene-transition metal dichalcogenide-based heterostructures as an excellent platform for studying the effects of broken symmetry on the physical properties of band-engineered two-dimensional systems.

3.
Aesthetic Plast Surg ; 48(3): 461-471, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-37943348

RESUMEN

BACKGROUND: Postoperative scar formation remains a morbidity for patients even with the advent of minimally invasive techniques. Furthermore, the significant difference between the Asian and Caucasian skin results in poorer postoperative scar outcomes in Asians, supporting the need for an evidence-based scar management protocol. METHODS: Following a literature review of the PubMed and the Cochrane databases over the past 10 years, we constructed a novel postoperative scar management protocol for the Asian skin, utilized in a Singaporean tertiary healthcare institution. RESULTS: We describe a timeline-based scar protocol from the point of skin closure to a minimum of 1 year of follow-up. We support the use of intraoperative botulinum toxin for selected high-risk individuals upon skin closure with a follow-up regimen in the postoperative setting. For recalcitrant keloids, we have described a multimodal therapy comprising elements of intralesional steroids, botulinum toxin, lasers, surgery, and radiotherapy. CONCLUSIONS: A consolidated postoperative scar management protocol provides the necessary guidance for improved scar outcomes in the Asian skin. There is inherent potential in expanding the protocol to include post-traumatic and burn wounds or support other skin types including the Caucasian skin. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .


Asunto(s)
Toxinas Botulínicas Tipo A , Queloide , Humanos , Pueblo Asiatico , Queloide/etiología , Queloide/cirugía
4.
Indian J Med Res ; 155(5&6): 546-553, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36348601

RESUMEN

Background & objectives: High mortality has been observed in the cancer population affected with COVID-19 during this pandemic. We undertook this study to determine the characteristics and outcomes of cancer patients with COVID-19 and assessed the factors predicting outcome. Methods: Patients of all age groups with a proven history of malignancy and a recent diagnosis of SARS-CoV-2 infection based on nasal/nasopharyngeal reverse transcriptase (RT)-PCR tests were included. Demographic, clinical and laboratory variables were compared between survivors and non-survivors groups, with respect to observed mortality. Results: Between May 11 and August 10, 2020, 134 patients were included from the three centres and observed mortality was 17.1 per cent. The median age was 53 yr (interquartile range 39-61 yr) and thirty four patients (25%) were asymptomatic. Solid tumours accounted for 69.1 per cent and breast cancer was the most common tumour type (20%). One hundred and five patients (70.5%) had received chemotherapy within the past four weeks and 25 patients (19.3%) had neutropenia at presentation. On multivariate analysis, age [odds ratio (OR) 7.99 (95% confidence interval [CI] 1.18-54.00); P=0.033], haemoglobin [OR 6.28 (95% CI 1.07-37.04); P=0.042] neutrophil-lymphocyte ratio [OR 12.02 (95% CI 2.08-69.51); P=0.005] and baseline serum albumin [OR 18.52 (95% CI 2.80-122.27); P=0.002], were associated with higher mortality. Recent chemotherapy, haematological tumours type and baseline neutropenia did not affect the outcome. Interpretation & conclusions: Higher mortality in moderate and severe infections was associated with baseline organ dysfunction and elderly age. Significant proportion of patients were asymptomatic and might remain undetected.


Asunto(s)
COVID-19 , Neoplasias , Neutropenia , Humanos , Anciano , Persona de Mediana Edad , Estudios Retrospectivos , SARS-CoV-2 , India/epidemiología , Neoplasias/complicaciones , Neoplasias/epidemiología , Neutropenia/complicaciones
5.
Phys Rev Lett ; 126(9): 096801, 2021 Mar 05.
Artículo en Inglés | MEDLINE | ID: mdl-33750179

RESUMEN

We report the discovery of electric-field-induced transition from a topologically trivial to a topologically nontrivial band structure in an atomically sharp heterostructure of bilayer graphene (BLG) and single-layer WSe_{2} per the theoretical predictions of Gmitra and Fabian [Phys. Rev. Lett. 119, 146401 (2017)PRLTAO0031-900710.1103/PhysRevLett.119.146401]. Through detailed studies of the quantum correction to the conductance in the BLG, we establish that the band-structure evolution arises from an interplay between proximity-induced strong spin-orbit interaction (SOI) and the layer polarizability in BLG. The low-energy carriers in the BLG experience an effective valley Zeeman SOI that is completely gate tunable to the extent that it can be switched on or off by applying a transverse displacement field or can be controllably transferred between the valence and the conduction band. We demonstrate that this results in the evolution from weak localization to weak antilocalization at a constant electronic density as the net displacement field is tuned from a positive to a negative value with a concomitant SOI-induced splitting of the low-energy bands of the BLG near the K(K^{'}) valley, which is a unique signature of the theoretically predicted spin-orbit valve effect. Our analysis shows that quantum correction to the Drude conductance in Dirac materials with strong induced SOI can only be explained satisfactorily by a theory that accounts for the SOI-induced spin splitting of the BLG low-energy bands. Our results demonstrate the potential for achieving highly tunable devices based on the valley Zeeman effect in dual-gated two-dimensional materials.

6.
Pediatr Hematol Oncol ; 32(8): 576-84, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26558505

RESUMEN

Facilities for measuring methotrexate (MTX) levels are not available everywhere, potentially limiting administration of high-dose methotrexate (HDMTX). We hypothesized that serum creatinine alteration after HDMTX administration predicts MTX clearance. Overall, 122 cycles in 50 patients of non-Hodgkin lymphoma or acute lymphoblastic leukemia aged ≤18 years receiving HDMTX were enrolled prospectively. Plasma MTX levels were measured at 12, 24, 36, 48, 60, and 72 hours; serum creatinine was measured at baseline, 24, 48, and 72 hours. Correlation of plasma MTX levels with creatinine levels and changes in creatinine from baseline (Δ creatinine) were evaluated. Plasma MTX levels at 72 hours showed positive correlation with serum creatinine at 48 hours (P = .011) and 72 hours (P = .013) as also Δ creatinine at 48 hours (P = .042) and 72 hours (P = .045). However, cut-off value of either creatinine or Δ creatinine could not be established to reliably predict delayed MTX clearance. Greater than 50% Δ creatinine at 48 and 72 hours significantly predicted grade 3/4 leucopenia (P = .036 and P = .001, respectively) and thrombocytopenia (P = .012 and P = .009, respectively) but not mucositis (P = .827 and P = .910, respectively). Delayed MTX elimination did not predict any grade 3/4 toxicity. In spite of demonstration of significant correlation between serum creatinine and Δ creatinine with plasma MTX levels at 72 hours, cut-off value of either variable to predict MTX delay could not be established. Thus, either of these cannot be used as a surrogate for plasma MTX estimation. Interestingly, Δ creatinine effectively predicted hematological toxicities, which were not predicted by delayed MTX clearance.


Asunto(s)
Creatinina/sangre , Linfoma no Hodgkin , Metotrexato/administración & dosificación , Metotrexato/farmacocinética , Leucemia-Linfoma Linfoblástico de Células Precursoras , Adolescente , Niño , Preescolar , Femenino , Humanos , Linfoma no Hodgkin/sangre , Linfoma no Hodgkin/tratamiento farmacológico , Masculino , Metotrexato/efectos adversos , Leucemia-Linfoma Linfoblástico de Células Precursoras/sangre , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamiento farmacológico
7.
Chem Biol Drug Des ; 103(4): e14512, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38570316

RESUMEN

A thorough search for the development of innovative drugs to treat tuberculosis, especially considering the urgent need to address developing drug resistance, we report here a synthetic series of ethyl 3-benzoyl-7-morpholinoindolizine-1-carboxylate analogues (5a-o) as potent anti-tubercular agents. These morpholino-indolizines were synthesized by reacting 4-morpholino pyridinium salts, with various electron-deficient acetylenes to afford the ethyl 3-benzoyl-7-morpholinoindolizine-1-carboxylate analogues (5a-o). All synthesized intermediate and final compounds are characterized by spectroscopic methods such as 1H NMR, 13C NMR and HRMS and further examined for their anti-tubercular activity against the M. tuberculosis H37Rv strain (ATCC 27294-American type cell culture). All the compounds screened for anti-tubercular activity in the range of 6.25-50 µM against the H37Rv strain of Mycobacterium tuberculosis. Compound 5g showed prominent activity with MIC99 2.55 µg/mL whereas compounds 5d and 5j showed activity with MIC99 18.91 µg/mL and 25.07 µg/mL, respectively. In silico analysis of these compounds revealed drug-likeness. Additionally, the molecular target identification for Malate synthase (PDB 5CBB) is attained by computational approach. The compound 5g with a MIC99 value of 2.55 µg/mL against M. tuberculosis H37Rv emerged as the most promising anti-TB drug and in silico investigations suggest Malate synthase (5CBB) might be the compound's possible target.


Asunto(s)
Mycobacterium tuberculosis , Tuberculosis , Humanos , Antituberculosos , Relación Estructura-Actividad , Malato Sintasa , Morfolinos , Simulación del Acoplamiento Molecular , Pruebas de Sensibilidad Microbiana
8.
Nat Commun ; 15(1): 2335, 2024 Mar 14.
Artículo en Inglés | MEDLINE | ID: mdl-38485946

RESUMEN

This paper presents our findings on the recursive band gap engineering of chiral fermions in bilayer graphene doubly aligned with hBN. Using two interfering moiré potentials, we generate a supermoiré pattern that renormalizes the electronic bands of the pristine bilayer graphene, resulting in higher order fractal gaps even at very low energies. These Bragg gaps can be mapped using a unique linear combination of periodic areas within the system. To validate our findings, we use electronic transport measurements to identify the position of these gaps as a function of the carrier density. We establish their agreement with the predicted carrier densities and corresponding quantum numbers obtained using the continuum model. Our study provides strong evidence of the quantization of the momentum-space area of quasi-Brillouin zones in a minimally incommensurate lattice. It fills important gaps in the understanding of band structure engineering of Dirac fermions with a doubly periodic superlattice spinor potential.

9.
Int J Biol Macromol ; : 133285, 2024 Jun 24.
Artículo en Inglés | MEDLINE | ID: mdl-38925196

RESUMEN

In the current study, two sets of compounds: (E)-1-(2-(4-substitutedphenyl)-2-oxoethyl)-4-((hydroxyimino)methyl)pyridinium derivatives (3a-3e); and (E)-3-(substitutedbenzoyl)-7-((hydroxyimino)methyl)-2-substitutedindolizine-1-carboxylate derivatives (5a-5j), were synthesized and biologically evaluated against two strains of Mycobacterial tuberculosis (ATCC 25177) and multi-drug resistant (MDR) strains. Further, they were also tested in vitro against the mycobacterial InhA enzyme. The in vitro results showed excellent inhibitory activities against both MTB strains and compounds 5a-5j were found to be more potent, and their MIC values ranged from 5 to 16 µg/mL and 16-64 µg/mL against the M. tuberculosis (ATCC 25177) and MDR-TB strains, respectively. Compound 5h with phenyl and 4-fluorobenzoyl groups attached to the 2- and 3-position of the indolizine core was found to be the most active against both strains with MIC values of 5 µg/mL and 16 µg/mL, respectively. On the other hand, the two sets of compounds showed weak to moderate inhibition of InhA enzyme activity that ranged from 5 to 17 % and 10-52 %, respectively, with compound 5f containing 4-fluoro benzoyl group attached to the 3-position of the indolizine core being the most active (52 % inhibition of InhA). Unfortunately, there was no clear correlation between the InhA inhibitory activity and MIC values of the tested compounds, indicating the probability that they might have different modes of action other than InhA inhibition. Therefore, a computational investigation was conducted by employing molecular docking to identify their putative drug target(s) and, consequently, understand their mechanism of action. A panel of 20 essential mycobacterial enzymes was investigated, of which ß-ketoacyl acyl carrier protein synthase I (KasA) and pyridoxal-5'-phosphate (PLP)-dependent aminotransferase (BioA) enzymes were revealed as putative targets for compounds 3a-3e and 5a-5j, respectively. Moreover, in silico ADMET predictions showed adequate properties for these compounds, making them promising leads worthy of further optimization.

10.
Semin Fetal Neonatal Med ; 28(4): 101465, 2023 08.
Artículo en Inglés | MEDLINE | ID: mdl-37236846

RESUMEN

Studies have clearly shown that development of pain receptors starts as early as 20-weeks' gestation. Despite contrary belief, the human fetus develops a similar number of receptive pain fibers as seen in adults. These receptors' maturation is based on response to sensory stimuli received after birth which makes the NICU a critical place for developing central nervous system's pain perception. In practice, the assessment of pain relies mostly on bedside staff. In this review we will discuss the various developing features of pain pathways in the neonatal brain and the modification of pain perception secondary to various interactions immediately after birth. We also discuss the various tools utilized in the NICU for pain assessment that rely on physiological and behavioral patterns. Finally, we address the management of pain in the NICU by either pharmacological or non-pharmacological intervention while highlighting potential benefits, disadvantages, and situations where one may be preferred over another.


Asunto(s)
Unidades de Cuidado Intensivo Neonatal , Dolor , Recién Nacido , Adulto , Humanos , Edad Gestacional , Dimensión del Dolor
11.
Mol Neurobiol ; 60(1): 203-227, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36251234

RESUMEN

Neuroinflammation is associated with activation of glial cells and pro-inflammatory arm of the central Renin Angiotensin System (RAS) namely, Angiotensin-Converting Enzyme/Angiotensin II/Angiotensin Type 1 Receptor (ACE/Ang II/AT1R) axis. Apart from this, another axis of RAS also exists, Angiotensin-Converting Enzyme 2/Angiotensin (1-7)/Mas Receptor (ACE2/Ang (1-7)/MasR), which counters ACE/Ang II/AT1R axis by showing anti-inflammatory properties. However, the role of ACE2/Ang (1-7)/MasR axis has not been explored in glial activation and neuroinflammation. Hence, the present study tries to unveil the role of ACE2/Ang (1-7)/MasR axis in lipopolysaccharide (LPS)-induced neuroinflammation using diminazene aceturate (DIZE), an ACE2 activator, in astroglial (C6) and microglial (BV2) cells as well as male SD rats. We found that ACE2 activation efficiently prevented LPS-induced changes by decreasing glial activation, inflammatory signaling, cell migration, ROS generation via upregulation of ACE2/Ang (1-7)/MasR signaling. In addition, activation of ACE2/Ang (1-7)/MasR axis by DIZE significantly suppressed the pro-inflammatory ACE/Ang II/AT1R axis by reducing Ang II level in neuroinflammatory conditions induced by LPS in both in vitro and in vivo. ACE2/Ang (1-7)/MasR axis activation further decreased mitochondrial depolarization and apoptosis, hence providing neuroprotection. Furthermore, to validate that the beneficial effect of the ACE2 activator was indeed through MasR, a selective MasR antagonist (A779) was used that significantly blocked the anti-inflammatory effect of ACE2 activation by DIZE. Hence, our study demonstrated that ACE2 activation imparted neuroprotection by enhancing ACE2/Ang (1-7)/MasR signaling which in turn decreased glial activation, neuroinflammation, and apoptosis and improved mitochondrial health.


Asunto(s)
Enzima Convertidora de Angiotensina 2 , Neuroglía , Animales , Masculino , Ratas , Angiotensina I/farmacología , Angiotensina II/farmacología , Antiinflamatorios , Lipopolisacáridos/farmacología , Enfermedades Neuroinflamatorias , Fragmentos de Péptidos/farmacología , Ratas Sprague-Dawley , Receptor de Angiotensina Tipo 1 , Receptores Acoplados a Proteínas G , Neuroglía/efectos de los fármacos
12.
Curr Med Chem ; 30(24): 2762-2795, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36154583

RESUMEN

Multi-targeted agents can interact with multiple targets sequentially, resulting in synergistic and more effective therapies for several complicated disorders, including cancer, even with relatively modest activity. Histone deacetylase (HDAC) inhibitors are low molecular weight small compounds that increase the acetylation of histone and nonhistone proteins, altering gene expression and thereby impacting angiogenesis, metastasis, and apoptosis, among other processes. The HDAC inhibitors affect multiple cellular pathways thus producing adverse issues, causing therapeutic resistance, and they have poor pharmacokinetic properties. The designing of HDAC-based dual/multi-target inhibitor is an important strategy to overcome adverse effects, drug resistance and increase the effectiveness in controlling cancer. The selection of target combinations to design multitarget HDAC inhibitor is generally accomplished on the basis of systematic highthroughput screening (HTS), network pharmacology analysis methods. The identification of the pharmacophore against individual targets is performed using rational or computation methods. The identified pharmacophore can combine with merged, fused, or linked with the cleavable or non-cleavable linker to retain the interaction with the original target while being compatible with the other target. The objective of this review is to elucidate the potential targets' design strategies, biological activity, and the recent development of dual/multi-targeting HDAC inhibitors as potential anticancer agents. This review elucidates the designing strategies of the potential target along with biological activity and the recent development of dual/multi-targeting HDAC inhibitors as potential anticancer agents. The development of HDAC-based dual/multi-target inhibitors is important for overcoming side effects, drug resistance, and effective cancer control.


Asunto(s)
Antineoplásicos , Neoplasias , Antineoplásicos/farmacología , Inhibidores de Histona Desacetilasas/farmacología , Inhibidores de Histona Desacetilasas/uso terapéutico , Neoplasias/metabolismo
13.
Eur J Pharmacol ; 943: 175558, 2023 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-36731722

RESUMEN

PURPOSE: Protective effect of 17ß-estradiol is well-known in pulmonary hypertension. However, estrogen-based therapy may potentially increase the risk of breast cancer, necessitating a search for novel drugs. This study, therefore, investigated the ameliorative effects of a selective estrogen receptor modulator, ormeloxifene, in pulmonary hypertension. METHODS: Cardiomyocytes (H9C2) and human pulmonary arterial smooth muscle cells (HPASMCs) were exposed to hypoxia (1% O2) for 42 and 96 h, respectively, with or without ormeloxifene pre-treatment (1 µM). Also, female (ovary-intact or ovariectomized) and male Sprague-Dawley rats received monocrotaline (60 mg/kg, once, subcutaneously), with or without ormeloxifene treatment (2.5 mg/kg, orally) for four weeks. RESULTS: Hypoxia dysregulated 17ß-hydroxysteroid dehydrogenase (17ßHSD) 1 & 2 expressions, reducing 17ß-estradiol production and estrogen receptors α and ß in HPASMC but increasing estrone, proliferation, inflammation, oxidative stress, and mitochondrial dysfunction. Similarly, monocrotaline decreased plasma 17ß-estradiol and uterine weight in ovary-intact rats. Further, monocrotaline altered 17ßHSD1 & 2 expressions and reduced estrogen receptors α and ß, increasing right ventricular pressure, proliferation, inflammation, oxidative stress, endothelial dysfunction, mitochondrial dysfunction, and vascular remodeling in female and male rats, with worsened conditions in ovariectomized rats. Ormeloxifene was less uterotrophic; however, it attenuated both hypoxia and monocrotaline effects by improving pulmonary 17ß-estradiol synthesis. Furthermore, ormeloxifene decreased cardiac hypertrophy and right ventricular remodeling induced by hypoxia and monocrotaline. CONCLUSION: This study demonstrates that ormeloxifene promoted pulmonary 17ß-estradiol synthesis, alleviated inflammation, improved the NOX4/HO1/Nrf/PPARγ/PGC-1α axis, and attenuated pulmonary hypertension. It is evidently safe at tested concentrations and may be effectively repurposed for pulmonary hypertension treatment.


Asunto(s)
Hipertensión Pulmonar , Moduladores Selectivos de los Receptores de Estrógeno , Ratas , Masculino , Femenino , Humanos , Animales , Moduladores Selectivos de los Receptores de Estrógeno/efectos adversos , Hipertensión Pulmonar/tratamiento farmacológico , Hipertensión Pulmonar/prevención & control , Hipertensión Pulmonar/inducido químicamente , Ratas Sprague-Dawley , Receptor alfa de Estrógeno , Monocrotalina/efectos adversos , Estradiol/farmacología , Estradiol/uso terapéutico , Arteria Pulmonar , Inflamación , Hipoxia
14.
Eur J Pharmacol ; 946: 175623, 2023 May 05.
Artículo en Inglés | MEDLINE | ID: mdl-36871666

RESUMEN

Activation of the renin-angiotensin system (RAS), by Angiotensin converting enzyme/Angiotensin II/Angiotensin receptor-1 (ACE/Ang II/AT1 R) axis elicits amyloid deposition and cognitive impairment. Furthermore, ACE2 induced release of Ang-(1-7) binds with the Mas receptor and autoinhibits ACE/Ang II/AT1 axis activation. Inhibition of ACE by perindopril has been reported to improve memory in preclinical settings. However, the functional significance and mechanism by which ACE2/Mas receptor regulate cognitive functions and amyloid pathology is not known. The present study is aimed to determine the role of ACE2/Ang-(1-7)/Mas receptor axis in STZ induced rat model of Alzheimer's disease (AD). We have used pharmacological, biochemical and behavioural approaches to identify the role of ACE2/Ang-(1-7)/Mas receptor axis activation on AD-like pathology in both in vitro and invivo models. STZ treatment enhances ROS formation, inflammation markers and NFκB/p65 levels which are associated with reduced ACE2/Mas receptor levels, acetylcholine activity and mitochondrial membrane potential in N2A cells. DIZE mediated ACE2/Ang-(1-7)/Mas receptor axis activation resulted in reduced ROS generation, astrogliosis, NFκB level and inflammatory molecules and improved mitochondrial functions along with Ca2+ influx in STZ treated N2A cells. Interestingly, DIZE induced activation of ACE2/Mas receptor significantly restored acetylcholine levels and reduced amyloid-beta and phospho-tau deposition in cortex and hippocampus that resulted in improved cognitive function in STZ induced rat model of AD-like phenotypes. Our data indicate that ACE2/Mas receptor activation is sufficient to prevented cognitive impairment and progression of amyloid pathology in STZ induced rat model of AD-like phenotypes. These findings suggest the potential role of ACE2/Ang-(1-7)/Mas axis in AD pathophysiology by regulating inflammation cognitive functions.


Asunto(s)
Enfermedad de Alzheimer , Ratas , Animales , Enfermedad de Alzheimer/patología , Estreptozocina , Enzima Convertidora de Angiotensina 2/genética , Especies Reactivas de Oxígeno , Acetilcolina , Peptidil-Dipeptidasa A/metabolismo , Cognición , Inflamación/tratamiento farmacológico , Fenotipo , Fragmentos de Péptidos/farmacología , Angiotensina I/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Angiotensina II/farmacología
15.
ACS Chem Neurosci ; 13(10): 1491-1504, 2022 05 18.
Artículo en Inglés | MEDLINE | ID: mdl-35533351

RESUMEN

Hypertension is reported to cause major brain disorders including Parkinson's disease (PD), apart from cardiovascular and chronic kidney disorders. Considering this, for the first time, we explored the effect of modulation of the ACE2/Ang (1-7)/MasR axis using diminazene aceturate (DIZE), an ACE2 activator, in 6-hydroxydopamine (6-OHDA) induced PD model. We found that DIZE treatment improved neuromuscular coordination and locomotor deficits in the 6-OHDA induced PD rat model. Further, the DIZE-mediated activation of ACE2 led to increased tyrosine hydroxylase (TH) and dopamine transporters (DAT) expression in the rat brain, indicating the protection of dopaminergic (DAergic) neurons from 6-OHDA induced neurotoxicity. Moreover, 6-OHDA induced activation of glial cells (astrocytes and microglia) and release of neuroinflammatory mediators were attenuated by DIZE treatment in both in vitro as well as in vivo models of PD. DIZE exerted its effect by activating ACE2 that produced Ang (1-7), a neuroprotective peptide. Ang (1-7) conferred its neuroprotective effect upon binding with the G-protein-coupled MAS receptor that led to the upregulation of cell survival proteins while downregulating apoptotic proteins. Importantly, these findings were further validated by using A-779, a MasR antagonist. The result showed that treatment with A-779 reversed the antioxidative and anti-inflammatory effects of DIZE by decreasing glial activation and neuroinflammatory markers. Although the role of ACE2 in PD pathology needs to be additionally confirmed using transgenic models in either ACE2 overexpressing or knockout mice, still, our study demonstrates that enhancing ACE2 activity could be a novel approach for ameliorating PD pathology.


Asunto(s)
Enzima Convertidora de Angiotensina 2 , Diminazeno/análogos & derivados , Enfermedad de Parkinson , Angiotensina I/metabolismo , Enzima Convertidora de Angiotensina 2/metabolismo , Animales , Diminazeno/farmacología , Ratones , Modelos Teóricos , Oxidopamina/toxicidad , Enfermedad de Parkinson/tratamiento farmacológico , Enfermedad de Parkinson/enzimología , Fragmentos de Péptidos/metabolismo , Peptidil-Dipeptidasa A/metabolismo , Proto-Oncogenes Mas/metabolismo , Ratas , Receptores Acoplados a Proteínas G/metabolismo , Transducción de Señal/efectos de los fármacos
16.
Curr Top Med Chem ; 22(22): 1849-1867, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36082857

RESUMEN

BACKGROUND: The management of Alzheimer's disease is challenging due to its complexity. However, the currently approved and marketed treatments for this neurodegenerative disorder revolves around cholinesterase inhibitors, glutamate regulators, or the combination of these agents. Despite the prompt assurance of many new drugs, several agents were unsuccessful, especially in phase II or III trials, not meeting efficacy endpoints. OBJECTIVE: The execution of effective treatment approaches through further trials investigating a rational combination of agents is necessitude for Alzheimer's disease. METHODS: For this review, more than 248 relevant scientific papers were considered from a variety of databases (Scopus, Web of Science, Google Scholar, ScienceDirect, and PubMed) using the keywords Alzheimer's disease, amyloid-ß, combination therapies, cholinesterase inhibitors, dementia, glutamate regulators, AD hypothesis. RESULT AND DISCUSSION: The researcher's intent is to either develop a disease-modifying therapeutic means for aiming in the early phases of dementia and/or optimize the available symptomatic treatments principally committed to the more advanced stages of Alzheimer's. Since Alzheimer's possesses multifactorial pathogenesis, designing a multimodal therapeutic intervention for targeting different pathological processes of dementia may appear to be the most practical method to alter the course of disease progression. CONCLUSION: The combination approach may even allow for providing individual agents in lower doses, with reducible costs and side effects. Numerous studies on combination therapy predicted better clinical efficacy than monotherapy. The literature review highlights the major clinical studies (both symptomatic and disease-modifying) conducted in the past decade on combination therapy to combat cognitive disorder.


Asunto(s)
Enfermedad de Alzheimer , Humanos , Enfermedad de Alzheimer/tratamiento farmacológico , Inhibidores de la Colinesterasa/farmacología , Inhibidores de la Colinesterasa/uso terapéutico , Péptidos beta-Amiloides , Glutamatos/uso terapéutico
17.
Indian J Cancer ; 59(4): 515-520, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-34380824

RESUMEN

Background: Medulloblastoma is the commonest embryonal brain tumor in children. It has shown improved outcomes with combined modality treatment. We aimed to study patient characteristics and survival outcomes of patients with this disease across two tertiary care centers in India. Methods: We analyzed data of patients with histological diagnosis of medulloblastoma treated from January 2010 to January 2016. Patient characteristics and follow-up data were retrieved from hospital records. Descriptive statistics were used to describe clinical and pathological characteristics. Overall survival (OS) was calculated from date of diagnosis to death due to any cause. Relapse-free survival (RFS) was calculated from date of diagnosis to occurrence of relapse or death. Result: Out of 26 patients treated, 24 were children and 2 were adults. Median age was 10 years (range = 0.8-22 years). Twenty (76.9%) patients were male. Fifteen (57.7%) patients were stratified as high-risk (HR), rest 11 (42.3%) were categorized as average risk (AR). Histopathology showed classical variety in majority of patients except for 4 (15%) cases, 3 with desmoplastic and 1 with anaplastic subtype. Median follow-up was 49.7 months (range= 4.2-102.5 months). Overall, eight (30.8%) patients relapsed and six (23%) deaths occurred. Five (33.3%) patients in HR category and 3 (27.3%) patients in AR group showed relapse. Median RFS and OS were not yet reached. Five-year RFS was 69.2% whereas five-year OS was 76.9%. Conclusion: This study highlighted patient characteristics and treatment outcomes in Indian patients. With adherence to standard treatment, high remission rates and improvement in mortality rates were achieved.


Asunto(s)
Neoplasias Cerebelosas , Meduloblastoma , Adulto , Niño , Humanos , Masculino , Lactante , Preescolar , Adolescente , Adulto Joven , Femenino , Meduloblastoma/epidemiología , Meduloblastoma/terapia , Estudios Retrospectivos , Atención Terciaria de Salud , Resultado del Tratamiento , Terapia Combinada , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Supervivencia sin Enfermedad
18.
Indian J Cancer ; 59(Supplement): S19-S45, 2022 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-35343189

RESUMEN

To gain insights on the diverse practice patterns and treatment pathways for prostate cancer (PC) in India, the Urological Cancer Foundation convened the first Indian survey to discuss all aspects of PC, with the objective of guiding clinicians on optimizing management in PC. A modified Delphi method was used, wherein a multidisciplinary panel of oncologists treating PC across India developed a questionnaire related to screening, diagnosis and management of early, locally advanced and metastatic PC and participated in a web-based survey (WBS) (n = 62). An expert committee meeting (CM) (n = 48, subset from WBS) reviewed the ambiguous questions for better comprehension and reanalyzed the evidence to establish a revote for specific questions. The threshold for strong agreement and agreement was ≥90% and ≥75% agreement, respectively. Sixty-two questions were answered in the WBS; in the CM 31 questions were revoted and 4 questions were added. The panelists selected answers based on their best opinion and closest to their practice strategy, not considering financial constraints and access challenges. Of the 66 questions, strong agreement was reached for 17 questions and agreement was achieved for 22 questions. There were heterogeneous responses for 27 questions indicative of variegated management approaches. This is one of the first Indian survey, documenting the diverse clinical practice patterns in the management of PC in India. It aims to provide guidance in the face of technological advances, resource constraints and sparse high-level evidence.


Asunto(s)
Neoplasias de la Próstata , Humanos , India/epidemiología , Masculino , Pautas de la Práctica en Medicina , Neoplasias de la Próstata/diagnóstico , Neoplasias de la Próstata/epidemiología , Neoplasias de la Próstata/terapia , Encuestas y Cuestionarios
20.
ACS Nano ; 15(1): 916-922, 2021 Jan 26.
Artículo en Inglés | MEDLINE | ID: mdl-33378173

RESUMEN

Topological insulators, along with Chern insulators and quantum Hall insulator phases, are considered as paradigms for symmetry protected topological phases of matter. This article reports the experimental realization of the time-reversal invariant helical edge-modes in bilayer graphene/monolayer WSe2-based heterostructures-a phase generally considered as a precursor to the field of generic topological insulators. Our observation of this elusive phase depended crucially on our ability to create mesoscopic devices comprising both a moiré superlattice potential and strong spin-orbit coupling; this resulted in materials whose electronic band structure could be tuned from trivial to topological by an external displacement field. We find that the topological phase is characterized by a bulk bandgap and by helical edge-modes with electrical conductance quantized exactly to 2e2/h in zero external magnetic field. We put the helical edge-modes on firm ground through supporting experiments, including the verification of predictions of the Landauer-Büttiker model for quantum transport in multiterminal mesoscopic devices. Our nonlocal transport properties measurements show that the helical edge-modes are dissipationless and equilibrate at the contact probes. We achieved the tunability of the different topological phases with electric and magnetic fields, which allowed us to achieve topological phase transitions between trivial and multiple, distinct topological phases. We also present results of a theoretical study of a realistic model which, in addition to replicating our experimental results, explains the origin of the topological insulating bulk and helical edge-modes. Our experimental and theoretical results establish a viable route to realizing the time-reversal invariant Z2 topological phase of matter.

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