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Cotranscriptional RNA folding is widely assumed to influence the timely control of gene expression, but our understanding remains limited. In bacteria, the fluoride (F-)-sensing riboswitch is a transcriptional control element essential to defend against toxic F- levels. Using this model riboswitch, we find that its ligand F- and essential bacterial transcription factor NusA compete to bind the cotranscriptionally folding RNA, opposing each other's modulation of downstream pausing and termination by RNA polymerase. Single-molecule fluorescence assays probing active transcription elongation complexes discover that NusA unexpectedly binds highly reversibly, frequently interrogating the complex for emerging, cotranscriptionally folding RNA duplexes. NusA thus fine-tunes the transcription rate in dependence of the ligand-responsive higher-order structure of the riboswitch. At the high NusA concentrations found intracellularly, this dynamic modulation is expected to lead to adaptive bacterial transcription regulation with fast response times.
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Proteínas de Escherichia coli/metabolismo , Ligantes , Riboswitch , Fatores de Transcrição/metabolismo , Fatores de Elongação da Transcrição/metabolismo , RNA Polimerases Dirigidas por DNA/química , RNA Polimerases Dirigidas por DNA/metabolismo , Escherichia coli/genética , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica , Dobramento de RNA , RNA Bacteriano/genética , Fatores de Transcrição/genética , Transcrição Gênica , Fatores de Elongação da Transcrição/química , Fatores de Elongação da Transcrição/genéticaRESUMO
BACKGROUND: Advanced stage operable cancers of larynx are treated with total laryngectomy including thyroid resection in most of the cases, which may expose patient to hypothyroidism and hypoparathyroidism. The requirement of thyroidectomy during Total Laryngectomy is controversial. METHODS: A cross sectional observational study was set out to review preoperative clinical and radiological assessment; intraoperative and histopathological findings; and follow-up data to predict thyroid gland invasion in the setting of squamous cell carcinoma of the Larynx. RESULTS: 11 (16%) out of 69 patients had thyroid gland involvement on histopathological examination with mean age 63 years. Out of these 11 cases, 8 (72%) underwent primary total laryngectomy. 90% patients with thyroid gland involvement were male. 9 cases with thyroid gland involvement were staged as T4a preoperatively. CONCLUSION: Invasion of thyroid gland by laryngeal cancer is uncommon. Unnecessary hemithyroidectomies lead to hypothyroidism and hypoparathyroidism. The study points out the clear indications of thyroid excision in patients undergoing total laryngectomy. We can suggest that total thyroidectomy should be done with total laryngectomy in cases which have gross clinical, radiological or intraoperative thyroid gland involvement, subglottic extension and thyroid cartilage invasion. This can save the patients from the brunt of unnecessary morbid hypothyroidism and hypoparathyroidism.
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Carcinoma de Células Escamosas/cirurgia , Neoplasias Laríngeas/cirurgia , Laringectomia , Tireoidectomia , Adulto , Idoso , Carcinoma de Células Escamosas/diagnóstico por imagem , Carcinoma de Células Escamosas/patologia , Estudos Transversais , Feminino , Glote/diagnóstico por imagem , Glote/patologia , Humanos , Neoplasias Laríngeas/diagnóstico por imagem , Neoplasias Laríngeas/patologia , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica/diagnóstico por imagem , Invasividade Neoplásica/patologia , Cuidados Pré-Operatórios , Cartilagem Tireóidea/diagnóstico por imagem , Cartilagem Tireóidea/patologia , Glândula Tireoide/diagnóstico por imagem , Glândula Tireoide/patologia , Glândula Tireoide/cirurgia , Tireoidectomia/efeitos adversos , Procedimentos Desnecessários/efeitos adversosRESUMO
Raman spectroscopy is a promising tool for neurosurgical guidance and cancer research. Quantitative analysis of the Raman signal from living tissues is, however, limited. Their molecular composition is convoluted and influenced by clinical factors, and access to data is limited. To ensure acceptance of this technology by clinicians and cancer scientists, we need to adapt the analytical methods to more closely model the Raman-generating process. Our objective is to use feature engineering to develop a new representation for spectral data specifically tailored for brain diagnosis that improves interpretability of the Raman signal while retaining enough information to accurately predict tissue content. The method consists of band fitting of Raman bands which consistently appear in the brain Raman literature, and the generation of new features representing the pairwise interaction between bands and the interaction between bands and patient age. Our technique was applied to a dataset of 547 in situ Raman spectra from 65 patients undergoing glioma resection. It showed superior predictive capacities to a principal component analysis dimensionality reduction. After analysis through a Bayesian framework, we were able to identify the oncogenic processes that characterize glioma: increased nucleic acid content, overexpression of type IV collagen and shift in the primary metabolic engine. Our results demonstrate how this mathematical transformation of the Raman signal allows the first biological, statistically robust analysis of in vivo Raman spectra from brain tissue.
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Neoplasias Encefálicas/metabolismo , Glioma/metabolismo , Análise Espectral Raman/métodos , Teorema de Bayes , Neoplasias Encefálicas/química , Colágeno Tipo IV/metabolismo , Conjuntos de Dados como Assunto , Feminino , Glioma/química , Humanos , Cuidados Intraoperatórios , Luz , Masculino , Pessoa de Meia-Idade , Ácidos Nucleicos/metabolismo , Análise de Componente Principal , Estudos RetrospectivosRESUMO
The N-methyl-d-aspartate (NMDA) receptor ion-channel is activated by the binding of ligands, along with the application of action potential, important for synaptic transmission and memory functions. Despite substantial knowledge of the structure and function, the gating mechanism of the NMDA receptor ion channel for electric on-off signals is still a topic of debate. We investigate the NMDA receptor partition distribution and the associated channel's open-close electric signal trajectories using a combined approach of correlating single-molecule fluorescence photo-bleaching, single-molecule super-resolution imaging, and single-channel electric patch-clamp recording. Identifying the compositions of NMDA receptors, their spatial organization and distributions over live cell membranes, we observe that NMDA receptors are organized inhomogeneously: nearly half of the receptor proteins are individually dispersed; whereas others exist in heterogeneous clusters of around 50 nm in size as well as co-localized within the diffraction limited imaging area. We demonstrate that inhomogeneous interactions and partitions of the NMDA receptors can be a cause of the heterogeneous gating mechanism of NMDA receptors in living cells. Furthermore, comparing the imaging results with the ion-channel electric current recording, we propose that the clustered NMDA receptors may be responsible for the variation in the current amplitude observed in the on-off two-state ion-channel electric signal trajectories. Our findings shed new light on the fundamental structure-function mechanism of NMDA receptors and present a conceptual advancement of the ion-channel mechanism in living cells.
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Receptores de N-Metil-D-Aspartato/metabolismo , Imagem Individual de Molécula/métodos , Membrana Celular , Eletricidade , Células HEK293 , Humanos , Ativação do Canal Iônico , Imagem Óptica/métodos , Técnicas de Patch-ClampRESUMO
N-methyl-d-aspartate (NMDA) receptor ion channel is activated by the binding of two pairs of glycine and glutamate along with the application of action potential. Binding and unbinding of ligands changes its conformation that plays a critical role in the open-close activities of NMDA receptor. Conformation states and their dynamics due to ligand binding are extremely difficult to characterize either by conventional ensemble experiments or single-channel electrophysiology method. Here we report the development of a new correlated technical approach, single-molecule patch-clamp FRET anisotropy imaging and demonstrate by probing the dynamics of NMDA receptor ion channel and kinetics of glycine binding with its ligand binding domain. Experimentally determined kinetics of ligand binding with receptor is further verified by computational modeling. Single-channel patch-clamp and four-channel fluorescence measurement are recorded simultaneously to get correlation among electrical on and off states, optically determined conformational open and closed states by FRET, and binding-unbinding states of the glycine ligand by anisotropy measurement at the ligand binding domain of GluN1 subunit. This method has the ability to detect the intermediate states in addition to electrical on and off states. Based on our experimental results, we have proposed that NMDA receptor gating goes through at least one electrically intermediate off state, a desensitized state, when ligands remain bound at the ligand binding domain with the conformation similar to the fully open state.
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Transferência Ressonante de Energia de Fluorescência , Glicina/metabolismo , Glicina/farmacologia , Microscopia , Receptores de N-Metil-D-Aspartato/agonistas , Receptores de N-Metil-D-Aspartato/metabolismo , Anisotropia , Sobrevivência Celular , Células HEK293 , Humanos , Cinética , Ligantes , Modelos Moleculares , Ligação Proteica , Domínios Proteicos , Receptores de N-Metil-D-Aspartato/químicaRESUMO
In this work, we have addressed the problem of "acidity" of the water-pool of a reverse micelle (RM) through the well-known inversion of sucrose reaction as a tool of investigation. This reaction has been performed inside positively and negatively charged RM and the rates are compared with that in bulk water. We propose that the buffer-like action in a water-pool is much stronger than expected earlier. The rate of sucrose hydrolysis slowed down in the negatively charged AOT reverse micelle while it sped up for the positively charged CTAB reverse micelle. However, temperature-dependent measurements showed that the activation energy remained the same for all the cases. It has been concluded that a proton gradient exists inside the water-pool of the reverse micelle and it determines the buffer-like action of the water-pool that persists until about 2 N of HCl in AOT RM of w(0) = 10.5.
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The present work reports the effect of confinement, and temperature therein, on the conformational fluctuation dynamics of domain-I of human serum albumin (HSA) by fluorescence correlation spectroscopy (FCS). The water-pool of a sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelle has been used as the confined environment. It was observed that the conformational fluctuation time is about 6 times smaller compared to bulk medium when confined in a water-pool of 3.5 nm radius. On increasing the size of the water-pool the conformational fluctuation time was found to increase monotonically and approaches the bulk value. The effect of confinement is on par with the general belief about the restricted motion of a macromolecule upon confinement. However, the effect of temperature was found to be surprising. An increase in the temperature from 298 K to 313 K induces a larger change in the conformational fluctuation time in HSA, when confined. In the bulk medium, apparently there is no change in the conformational fluctuation time in the aforementioned temperature range, whereas, when HSA is present in an AOT water-pool of radius 3.5 nm, about an 88% increase in the fluctuation time was observed. The observed prominent thermal effect on the conformational dynamics of domain-I of HSA in the water-pool of an AOT reverse micelle as compared to in the bulk medium was concluded to arise from the confined solvent effect.
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Micelas , Albumina Sérica Humana/metabolismo , Ácido Dioctil Sulfossuccínico/química , Humanos , Estrutura Terciária de Proteína , Rodaminas/química , Albumina Sérica Humana/química , Espectrometria de Fluorescência , Temperatura , Água/químicaRESUMO
DEAD-box RNA helicases are ubiquitous in all domains of life where they bind and remodel RNA and RNA-protein complexes. DEAD-box helicases unwind RNA duplexes by local opening of helical regions without directional movement through the duplexes and some of these enzymes, including Ded1p from Saccharomyces cerevisiae, oligomerize to effectively unwind RNA duplexes. Whether and how DEAD-box helicases coordinate oligomerization and unwinding is not known and it is unclear how many base pairs are actively opened. Using high-resolution optical tweezers and fluorescence, we reveal a highly dynamic and stochastic process of multiple Ded1p protomers assembling on and unwinding an RNA duplex. One Ded1p protomer binds to a duplex-adjacent ssRNA tail and promotes binding and subsequent unwinding of the duplex by additional Ded1p protomers in 4-6 bp steps. The data also reveal rapid duplex unwinding and rezipping linked with binding and dissociation of individual protomers and coordinated with the ATP hydrolysis cycle.
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Safe and effective brain tumor surgery aims to remove tumor tissue, not non-tumoral brain. This is a challenge since tumor cells are often not visually distinguishable from peritumoral brain during surgery. To address this, we conducted a multicenter study testing whether the Sentry System could distinguish the three most common types of brain tumors from brain tissue in a label-free manner. The Sentry System is a new real time, in situ brain tumor detection device that merges Raman spectroscopy with machine learning tissue classifiers. Nine hundred and seventy-six in situ spectroscopy measurements and colocalized tissue specimens were acquired from 67 patients undergoing surgery for glioblastoma, brain metastases, or meningioma to assess tumor classification. The device achieved diagnostic accuracies of 91% for glioblastoma, 97% for brain metastases, and 96% for meningiomas. These data show that the Sentry System discriminated tumor containing tissue from non-tumoral brain in real time and prior to resection.
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Neoplasias Encefálicas , Análise Espectral Raman , Humanos , Neoplasias Encefálicas/diagnóstico , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/cirurgia , Análise Espectral Raman/métodos , Masculino , Feminino , Pessoa de Meia-Idade , Idoso , Meningioma/diagnóstico , Meningioma/patologia , Glioblastoma/patologia , Glioblastoma/diagnóstico , Glioblastoma/cirurgia , Adulto , Aprendizado de Máquina , Encéfalo/patologia , Encéfalo/diagnóstico por imagemRESUMO
Introduction India is responsible for the second-highest maternal deaths and the greatest burden of stillbirths worldwide. The cost of intranatal services is an important determining factor, especially in developing countries like India. Most studies report the cost of delivery from the patient's perspective, but there is a lack of studies from the health system's perspective. This present study aimed to bridge this gap by estimating the overall and unit costs of various types of deliveries at a tertiary-level hospital in Rajasthan, India. Methods The cost estimation of intranatal services was conducted in a tertiary-level teaching hospital in Jaipur, Rajasthan. This cost analysis undertook the health system's perspective, using bottom-up costing methodology. Data on all the resources (capital/recurrent) used for the delivery of intranatal care from April 2020 to March 2021 were collected. Sensitivity analysis was done to account for any variability in cost components on overall intranatal service cost. Results The annual cost of intranatal care services at the tertiary care hospital was INR 149,011,957 (USD 1,988,152). The unit cost per vaginal delivery was INR 8,244.4 (USD 109.9) and the unit cost per cesarean section was INR 10,696.2 (USD 142.7). Among various heads of expenditure, 'human resource' costs were predominant, accounting for 47.7% of the total costs, followed by 'building/space' and 'overhead' costs, accounting for 30.59% and 11.1%, respectively. Conclusion The results may help plan and manage intra-natal care services in Rajasthan. Apart from the judicious utilization of resources, the findings of the study may also serve as a basis for future health economic studies.
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BACKGROUND AND PURPOSE: The pathophysiology of postprandial distress syndrome includes impaired gastric accommodation, hypersensitivity to gastric distension and delayed gastric emptying. 2D-ultrasonography is one of the methods to assess gastric accommodation by measuring proximal gastric area and we evaluated its role in calculating proximal gastric area and thus assessing gastric accommodation in Indian patients with postprandial distress syndrome. METHODS: In a hospital-based comparative analysis, proximal gastric area was measured with 2D-ultrasonography of postprandial distress syndrome (PDS) patients and compared with healthy controls. Five readings were measured every five minutes till 25 minutes after 400 mL of vegetable soup. The Patient Assessment of Upper Gastrointestinal Disorders-Quality of Life (PAGI-QOL score) and diets aggravating PDS symptoms were studied through detailed questionnaires. Sample size was calculated at 80% study power and alpha error of 0.05 to be 30 subjects in each group. RESULTS: The mean age of patients (18 males) vs. 30 healthy controls (25 males) was 40.8 ± 11.50 years vs. 36.37 ± 7.58, respectively, (p = 0.084). Proximal gastric area was significantly lower in patients versus healthy controls at five minutes (22.54 ± 2.77 vs. 30.66 ± 2.55 cm2), 10 minutes (23.03 ± 2.45 vs. 31.10 ± 2.06 cm2), 15 minutes (23.06 ± 2.27 vs. 30.31 ± 2.11 cm2), 20 minutes (22.21 ± 2.31 vs. 29.73 ± 1.71 cm2) and 25 minutes (22.02 ± 2.33 vs. 28.39 ± 1.55 cm2); p < 0.001 at all intervals of time, indicating impaired gastric accommodation. The QOL was poor in all patients with PDS with mean PAGI-QOL score of 31.30 ± 15.05, median of 30, minimum score of 12 and maximum score of 66. CONCLUSIONS: Measurement of proximal gastric area with 2D-ultrasonography is simple and non-invasive. Proximal gastric area in patients was lower than controls, indicating impaired gastric accommodation. Poor quality of life was universal in patients with postprandial distress syndrome.
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Dispepsia , Gastropatias , Masculino , Humanos , Dispepsia/diagnóstico por imagem , Qualidade de Vida , Período Pós-Prandial/fisiologia , Estômago/diagnóstico por imagem , Ultrassonografia , Esvaziamento GástricoRESUMO
Significance: Lung cancer is the most frequently diagnosed cancer overall and the deadliest cancer in North America. Early diagnosis through current bronchoscopy techniques is limited by poor diagnostic yield and low specificity, especially for lesions located in peripheral pulmonary locations. Even with the emergence of robotic-assisted platforms, bronchoscopy diagnostic yields remain below 80%. Aim: The aim of this study was to determine whether in situ single-point fingerprint (800 to 1700 cm-1) Raman spectroscopy coupled with machine learning could detect lung cancer within an otherwise heterogenous background composed of normal tissue and tissue associated with benign conditions, including emphysema and bronchiolitis. Approach: A Raman spectroscopy probe was used to measure the spectral fingerprint of normal, benign, and cancer lung tissue in 10 patients. Each interrogated specimen was characterized by histology to determine cancer type, i.e., small cell carcinoma or non-small cell carcinoma (adenocarcinoma and squamous cell carcinoma). Biomolecular information was extracted from the fingerprint spectra to identify biomolecular features that can be used for cancer detection. Results: Supervised machine learning models were trained using leave-one-patient-out cross-validation, showing lung cancer could be detected with a sensitivity of 94% and a specificity of 80%. Conclusions: This proof of concept demonstrates fingerprint Raman spectroscopy is a promising tool for the detection of lung cancer during diagnostic procedures and can capture biomolecular changes associated with the presence of cancer among a complex heterogeneous background within less than 1 s.
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Adenocarcinoma , Carcinoma de Células Escamosas , Neoplasias Pulmonares , Humanos , Análise Espectral Raman , Neoplasias Pulmonares/diagnóstico por imagem , Pulmão/diagnóstico por imagemRESUMO
A new water-soluble, multisite-coordinating ligand LH(7) was prepared by the condensation of tris(hydroxymethyl)aminomethane with 2,6-diformyl-p-cresol. LH(7) is a selective chemosensor for Cu(2+), under physiological conditions, with visual detection limits of 20 ppm (ambient light conditions) and 4 ppm (UV light conditions). LH(7) can also be used in biological cell lines for the detection of Cu(2+).
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Complexos de Coordenação/química , Cobre/análise , Cresóis/química , Trometamina/química , Animais , Células COS , Chlorocebus aethiops , Cobre/química , Corantes Fluorescentes , Ligantes , Luz , Microscopia de Fluorescência , Imagem Molecular , Sensibilidade e Especificidade , Soluções , Espectrometria de Fluorescência , ÁguaRESUMO
We present an instrument that combines high-resolution optical tweezers and multicolor confocal fluorescence spectroscopy. Biological macromolecules exhibit complex conformation and stoichiometry changes in coordination with their motion and activity. To further our understanding of the complex machinery of life, we need methods that can simultaneously probe more than one degree of freedom of single molecules and complexes. Fluorescence optical tweezers, or "fleezers," combine the capabilities of optical tweezers and single-molecule fluorescence microscopy into a single instrument. Here we present the latest generation of a high-resolution fleezers instrument integrated with multicolor fluorescence spectroscopy. The tweezers portion of the instrument can manipulate biological macromolecules with pN scale forces while measuring subnanometer distances. Simultaneous with tweezers measurements, the multicolor fluorescence capability allows the direct observation of multiple molecules or multiple degrees of freedom which allows, for example, the observation of multiple proteins simultaneously within a complex. The instrument incorporates three fluorescence excitation lasers, all sourced from a single-mode optical fiber allowing a reliable alignment scheme, that allows, for example, three independent fluorescent probes or fluorescence resonance energy transfer (FRET) measurements and also increases flexibility in the choice of fluorescent probes. To avoid photobleaching and improve tweezers stability, the instrument implements a timesharing (using a single trap laser to produce a pair of traps via rapid switching between two locations) and interlacing (turning the trapping beam off when the fluorescence excitation beams are on and vice versa) scheme using acousto-optic modulators (AOM) to rapidly and precisely modulate lasers. Our latest "random phase" trap AOM control method obliterates previous residual trap positioning and bead position measurement errors. Here we present the general design principles and detailed construction and testing protocols for the instrument.
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Pinças Ópticas , Imagem Individual de Molécula , Transferência Ressonante de Energia de Fluorescência , Corantes Fluorescentes , Nanotecnologia/métodos , Imagem Individual de Molécula/métodosRESUMO
The archetypical transcriptional crcB fluoride riboswitch from Bacillus cereus is an intricately structured non-coding RNA element enhancing gene expression in response to toxic levels of fluoride. Here, we used single molecule FRET to uncover three dynamically interconverting conformations appearing along the transcription process: two distinct undocked states and one pseudoknotted docked state. We find that the fluoride anion specifically snap-locks the magnesium-induced, dynamically docked state. The long-range, nesting, single base pair A40-U48 acts as the main linchpin, rather than the multiple base pairs comprising the pseudoknot. We observe that the proximally paused RNA polymerase further fine-tunes the free energy to promote riboswitch docking. Finally, we show that fluoride binding at short transcript lengths is an early step toward partitioning folding into the docked conformation. These results reveal how the anionic fluoride ion cooperates with the magnesium-associated RNA to govern regulation of downstream genes needed for fluoride detoxification of the cell.
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Bacillus cereus/química , Fluoretos/química , Magnésio/química , RNA Bacteriano/química , RNA Mensageiro/química , Riboswitch , Bacillus cereus/genética , Bacillus cereus/metabolismo , Pareamento de Bases , RNA Polimerases Dirigidas por DNA/genética , RNA Polimerases Dirigidas por DNA/metabolismo , Fluoretos/farmacologia , Regulação Bacteriana da Expressão Gênica , Magnésio/metabolismo , Simulação de Acoplamento Molecular , Conformação de Ácido Nucleico , Ligação Proteica , RNA Bacteriano/genética , RNA Bacteriano/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , TermodinâmicaRESUMO
BACKGROUND: With increasing incidence of cancer worldwide and increasing burden of treatment over the patients with cancer, the caregivers of those patients with cancer also suffer from psychological distress which ultimately affects their Quality of Life (QOL). This aspect is often overlooked which may ultimately lead to compromised patient care. PURPOSE: To translate the Caregiver Quality of Life Index-Cancer (CQOLC) Scale in Hindi and assess its association with Kesslers's psychological distress scale (K-10) for determining the quality of life (QoL) of caregivers of patients with cancer in India. METHODS: This is a single institute, hospital based cross sectional study performed from July 2020 to March 2021. Caregiver Quality of Life Index-Cancer (CQOLC) Scale, employing standard 'forward-backforward' translation procedure, the English-language version of the questionnaire was translated into Hindi-language by experts and administered to each caregiver. Cronbach's alpha was used for internal consistency. Kesslers's psychological distress scale (K-10) was analysed on interview basis. RESULTS: A total evaluated responders were 264. The hindi versions of the CQOLC was validated by cronbach's alpha method with internal consistency between 0.8 and 0.91. The majority of the caregivers were of the age group 31-40 yrs (42.05%). The male to female ratio was 6.54:1. CQOLC good score(0-45) was obtained in 27.27%, fair(46-90) in 55.30% and poor(91-140) in 17.42%. For K-10 distress scale very mild(10-19), mild(20-24), moderate(25-29) and severe(30-50) was observed in 47.73%, 11.74%, 11.74% and 28.79% respectively. A strong relation was found between the caregivers with poor CQOLC score and severe K-10 score(p<0.001). CONCLUSION: The Hindi version of CQOLC was accepted and its correlation with the point psychological distress predictor (K-10) scale was a valuable method to identify caregivers with poor QOL and severe distress levels.
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Neoplasias , Angústia Psicológica , Adulto , Cuidadores/psicologia , Estudos Transversais , Feminino , Humanos , Índia , Idioma , Masculino , Neoplasias/terapia , Qualidade de Vida/psicologia , Reprodutibilidade dos TestesRESUMO
Ultrafast excited-state relaxation dynamics of a nonlinear optical (NLO) dye, (S)-(-)-1-(4-nitrophenyl)-2-pyrrolidinemethanol (NPP), was carried out under the regime of femtosecond fluorescence up-conversion measurements in augmentation with quantum chemical calculations. The primary concern was to trace the relaxation pathways which guide the depletion of the first singlet excited state upon photoexcitation, in such a way that it is virtually nonfluorescent. Ground- and excited-state (singlet and triplet) potential energy surfaces were calculated as a function of the -NO(2) torsional coordinate, which revealed the perpendicular orientation of -NO(2) in the excited state relative to the planar ground-state conformation. The fluorescence transients in the femtosecond regime show biexponential decay behavior. The first time component of a few hundred femtoseconds was ascribed to the ultrafast twisted intramolecular charge transfer (TICT). The occurrence of charge transfer (CT) is substantiated by the large dipole moment change during excitation. The construction of intensity- and area-normalized time-resolved emission spectra (TRES and TRANES) of NPP in acetonitrile exhibited a two-state emission on behalf of decay of the locally excited (LE) state and rise of the CT state with a Stokes shift of 2000 cm(-1) over a time scale of 1 ps. The second time component of a few picoseconds is attributed to the intersystem crossing (isc). In highly polar solvents both the processes occur on a much faster time scale compared to that in nonpolar solvents, credited to the differential stability of energy states in different polarity solvents. The shape of frontier molecular orbitals in the excited state dictates the shift of electron density from the phenyl ring to the -NO(2) group and is attributed to the charge-transfer process taking place in the molecule. The viscosity dependence of relaxation dynamics augments the proposition of considering the -NO(2) group torsional motion as the main excited-state relaxation coordinate.
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Nitrocompostos/química , Pirrolidinas/química , Teoria Quântica , Estrutura Molecular , Fatores de TempoRESUMO
INTRODUCTION: Physeal injuries of proximal tibia are uncommon and constitute only 1% of all physeal injuries. Major vessel injuries are also rare in children and occur in 0.6% trauma cases, out of which, injuries of popliteal artery comprise only 5%. The combination of these is an extremely rare injury pattern but is potentially limb threatening. Most of the cases of physeal injuries of proximal tibia along with popliteal artery compromise, reported in the literature include Salter Harris (SH) type II, III, and IV patterns (type II being most common) with pure type I being extremely rare. CASE REPORT: We describe a rare posteriorly displaced pure SH I injury of proximal tibial physis with compromised vascularity of the limb. Immediate closed reduction and stabilization with Kirschner wires (K-wires) restored the vascularity of the limb and the patient went on to have a good functional recovery at the last follow-up of 1 year. CONCLUSION: Vascular injuries occurring in SH 1 proximal tibial physeal fractures are often overlooked or missed due to the relatively benign appearance of slip with no sharp fragments to injure major vessels. Close monitoring of neurovascular status and a low threshold for fixation, for example, with K-wires, are important to prevent limb threatening ischemia in these relatively simple appearing injuries.
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INTRODUCTION: Various ossicular reconstruction materials and techniques have been described in literature using autologous ossicle, cortical bone, autologous cartilage, synthetic materials and implants like total/partial ossicular replacement prosthesis (TORP/PORP) etc., but it has always been a topic of controversy in terms of the efficacy, longevity and complications of the material or method used. MATERIAL AND METHODS: This is a prospective, interventional, comparative, double-blind randomized control study which was done at a tertiary care center to compare outcomes of conventional and carved conchal cartilage (vertical strut) type III Tympanoplasty in terms of graft uptake and hearing gain. A total number of 52 cases were enrolled, randomized and allocated to 2 groups (26 each) i.e. group A (conventional type III) and group B (vertical strut technique). RESULTS: Graft uptake was seen in 25 (96.16%) patients in group B while it was observed in 23 (88.5%) cases in group A. Hearing gains were also better in group B. CONCLUSION: This study suggests that Vertical Strut technique can be studied further as it gives better gains in Air Conduction threshold and A-B Gap along with graft uptake as it provides better middle ear space and ossicular / tympanic membrane interface resulting in better hearing.
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Tympanoplasty is the standard and well-established procedure for closure of tympanic membrane perforations. Tympanoplasty in wet ear is still a topic of debate among ENT surgeons. This study discusses the balance between wait and watch policy and early intervention in wet ear. It also compares the rate of graft uptake and hearing improvement in Type I tympanoplasty in dry and wet ears. This is a hospital based, observational, descriptive and comparative study. Total 246 patients enrolled in the study. Two groups were created with 123 patients in each group. One included dry ears and another included wet ears. All patients had mucosal type of chronic otitis media. They all underwent Type I tympanoplasty. Graft uptake rate and hearing was compared between both groups. The overall success rate (graft uptake) was 91.06% (224). The success rate in dry ear group was 93.50% (115) and in wet ear group it was 88.62% (109). This study concluded that there is no added advantage of drying the ear rather the delay in treatment increases morbidity and drop outs in Indian scenario.