Publications by authors named "Krishna Agarwal"

47 Publications

Cardiac Outcomes in Isolated Heart and Simultaneous Kidney and Heart Transplants in the United States.

Kidney Int Rep 2021 Sep 14;6(9):2348-2357. Epub 2021 Jul 14.

Division of Nephrology, Tufts Medical Center, Boston, Massachusetts, USA.

Introduction: Kidney dysfunction is not uncommon in patients with advanced heart failure. Simultaneous kidney and heart transplants (SKHTs) have gained acceptance as a treatment for patients with end-stage heart failure and severe kidney dysfunction. United States saw a rise of 650% in SKHT from 2000 to 2019. Despite increasing number of SKHT, the selection criteria remain poorly defined and vary across transplant centers.

Methods: We evaluated patient and cardiac allograft survival for SKHT and heart transplant alone (HTA) using the United Network for Organ Sharing (UNOS) database. We then performed a subgroup analysis in recipients with post-transplant acute kidney injury requiring renal replacement therapy (RRT) and compared outcomes between SKHT and HTA recipients.

Results: Although patient survival was comparable between SKHT and HTA groups (12.4 vs. 11.3 years), patients dependent on dialysis pretransplant derived greater survival advantage from SKHT as compared with HTA (12.4 vs. 9.9 years). Cardiac graft survival was better in SKHT (12.5 vs. 11.2 years). Among patients who developed acute kidney injury requiring RRT postoperatively, SKHT recipients had a significantly better survival (11.9 vs. 2.7 years).

Conclusion: Our data support consideration of SKHT in dialysis-dependent heart transplant candidates and suggest that patients who are at increased risk of requiring RRT after heart transplant may benefit from SKHT.
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http://dx.doi.org/10.1016/j.ekir.2021.06.032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8418976PMC
September 2021

Artefact removal in ground truth deficient fluctuations-based nanoscopy images using deep learning.

Biomed Opt Express 2021 Jan 8;12(1):191-210. Epub 2020 Dec 8.

Department of Computer Science, UiT The Arctic University of Norway, Tromsø, Norway.

Image denoising or artefact removal using deep learning is possible in the availability of supervised training dataset acquired in real experiments or synthesized using known noise models. Neither of the conditions can be fulfilled for nanoscopy (super-resolution optical microscopy) images that are generated from microscopy videos through statistical analysis techniques. Due to several physical constraints, a supervised dataset cannot be measured. Further, the non-linear spatio-temporal mixing of data and valuable statistics of fluctuations from fluorescent molecules that compete with noise statistics. Therefore, noise or artefact models in nanoscopy images cannot be explicitly learned. Here, we propose a robust and versatile simulation-supervised training approach of deep learning auto-encoder architectures for the highly challenging nanoscopy images of sub-cellular structures inside biological samples. We show the proof of concept for one nanoscopy method and investigate the scope of generalizability across structures, and nanoscopy algorithms not included during simulation-supervised training. We also investigate a variety of loss functions and learning models and discuss the limitation of existing performance metrics for nanoscopy images. We generate valuable insights for this highly challenging and unsolved problem in nanoscopy, and set the foundation for the application of deep learning problems in nanoscopy for life sciences.
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http://dx.doi.org/10.1364/BOE.410617DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7899514PMC
January 2021

On-chip TIRF nanoscopy by applying Haar wavelet kernel analysis on intensity fluctuations induced by chip illumination.

Opt Express 2020 Nov;28(24):35454-35468

Photonic-chip based TIRF illumination has been used to demonstrate several on-chip optical nanoscopy methods. The sample is illuminated by the evanescent field generated by the electromagnetic wave modes guided inside the optical waveguide. In addition to the photokinetics of the fluorophores, the waveguide modes can be further exploited for introducing controlled intensity fluctuations for exploitation by techniques such as super-resolution optical fluctuation imaging (SOFI). However, the problem of non-uniform illumination pattern generated by the modes contribute to artifacts in the reconstructed image. To alleviate this problem, we propose to perform Haar wavelet kernel (HAWK) analysis on the original image stack prior to the application of (SOFI). HAWK produces a computational image stack with higher spatio-temporal sparsity than the original stack. In the case of multimoded non-uniform illumination patterns, HAWK processing breaks the mode pattern while introducing spatio-temporal sparsity, thereby differentially affecting the non-uniformity of the illumination. Consequently, this assists nanoscopy methods such as SOFI to better support super-resolution, which is otherwise compromised due to spatial correlation of the mode patterns in the raw image. Furthermore, applying HAWK prior to SOFI alleviates the problem of artifacts due to non-uniform illumination without degrading temporal resolution. Our experimental results demonstrate resolution enhancement as well as reduction in artifacts through the combination of HAWK and SOFI.
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http://dx.doi.org/10.1364/OE.403804DOI Listing
November 2020

Object detection neural network improves Fourier ptychography reconstruction.

Opt Express 2020 Dec;28(25):37199-37208

High resolution microscopy is heavily dependent on superb optical elements and superresolution microscopy even more so. Correcting unavoidable optical aberrations during post-processing is an elegant method to reduce the optical system's complexity. A prime method that promises superresolution, aberration correction, and quantitative phase imaging is Fourier ptychography. This microscopy technique combines many images of the sample, recorded at differing illumination angles akin to computed tomography and uses error minimisation between the recorded images with those generated by a forward model. The more precise knowledge of those illumination angles is available for the image formation forward model, the better the result. Therefore, illumination estimation from the raw data is an important step and supports correct phase recovery and aberration correction. Here, we derive how illumination estimation can be cast as an object detection problem that permits the use of a fast convolutional neural network (CNN) for this task. We find that faster-RCNN delivers highly robust results and outperforms classical approaches by far with an up to 3-fold reduction in estimation errors. Intriguingly, we find that conventionally beneficial smoothing and filtering of raw data is counterproductive in this type of application. We present a detailed analysis of the network's performance and provide all our developed software openly.
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http://dx.doi.org/10.1364/OE.409679DOI Listing
December 2020

Silicon substrate significantly alters dipole-dipole resolution in coherent microscope.

Opt Express 2020 Dec;28(26):39713-39726

Considering a coherent microscopy setup, influences of the substrate below the sample in the imaging performances are studied, with a focus on high refractive index substrate such as silicon. Analytical expression of 3D full-wave vectorial point spread function, i.e. the dyadic Green's function is derived for the optical setup together with the substrate. Numerical analysis are performed in order to understand and compare magnification, depth of field, and resolution when using silicon substrate versus the conventional glass substrate or usually modelled condition of no substrate. Novel insights are generated about the scope of resolution improvement due to near field effect of the silicon substrate. Importantly, we show that the expected resolution varies greatly with the position of the sources and the substrate interface relative to the focal plane. Both better and worse resolution as compared to glass substrate may be expected with small changes in their positions. Therefore, our studies show that deriving a single indicative number of expected resolution is neither possible nor judicious for the case of silicon substrate.
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http://dx.doi.org/10.1364/OE.409629DOI Listing
December 2020

Soft thresholding schemes for multiple signal classification algorithm.

Opt Express 2020 Nov;28(23):34434-34449

Multiple signal classification algorithm (MUSICAL) exploits temporal fluctuations in fluorescence intensity to perform super-resolution microscopy by computing the value of a super-resolving indicator function across a fine sample grid. A key step in the algorithm is the separation of the measurements into signal and noise subspaces, based on a single user-specified parameter called the threshold. The resulting image is strongly sensitive to this parameter and the subjectivity arising from multiple practical factors makes it difficult to determine the right rule of selection. We address this issue by proposing soft thresholding schemes derived from a new generalized framework for indicator function design. We show that the new schemes significantly alleviate the subjectivity and sensitivity of hard thresholding while retaining the super-resolution ability. We also evaluate the trade-off between resolution and contrast and the out-of-focus light rejection using the various indicator functions. Through this, we create significant new insights into the use and further optimization of MUSICAL for a wide range of practical scenarios.
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http://dx.doi.org/10.1364/OE.409363DOI Listing
November 2020

Drug-Induced Thrombotic Microangiopathy Resulting in ESRD.

Kidney Int Rep 2020 Aug 2;5(8):1350-1355. Epub 2020 Jul 2.

Department of Medicine, Division of Nephrology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.

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http://dx.doi.org/10.1016/j.ekir.2020.06.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7403540PMC
August 2020

MusiJ: an ImageJ plugin for video nanoscopy.

Biomed Opt Express 2020 May 14;11(5):2548-2559. Epub 2020 Apr 14.

Department of Physics and Technology, UiT The Arctic University of Norway, NO-9037 Tromsø, Norway.

We present an open-source implementation of the fluctuation-based nanoscopy method MUSICAL for ImageJ. This implementation improves the algorithm's computational efficiency and takes advantage of multi-threading to provide orders of magnitude faster reconstructions than the original MATLAB implementation. In addition, the plugin is capable of generating super-resolution videos from large stacks of time-lapse images via an interleaved reconstruction, thus enabling easy-to-use multi-color super-resolution imaging of dynamic systems.
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http://dx.doi.org/10.1364/BOE.382735DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7249817PMC
May 2020

A Systematic Review of Sodium Disorders in HHV-6 Encephalitis.

Biol Blood Marrow Transplant 2020 05 3;26(5):1034-1039. Epub 2020 Feb 3.

Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts. Electronic address:

Human herpesvirus 6 (HHV-6) encephalitis has a high mortality rate. Among those who survive, ~80% develop some type of permanent neurologic disorder. Early diagnosis and treatment may help prevent long-term sequelae. There have been several case reports as well as retrospective and prospective studies associating HHV-6 encephalitis with some form of sodium imbalance, either hyponatremia or hypernatremia; however, the exact frequency post-HCT is unknown, with reports ranging from 30% to 100%. We performed a systematic review of the literature and found 34 cases of HHV-6 encephalitis reported in conjunction with sodium imbalance that documented the timing of that imbalance relative to the onset of encephalitis. Sodium imbalance occurred before or at the onset of HHV-6 encephalitis in all but 2 cases (94%). This finding supports previous suggestions that sodium imbalance can be considered an early indicator of the potential development or presence of HHV-6 encephalitis in at-risk patient populations.
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http://dx.doi.org/10.1016/j.bbmt.2020.01.023DOI Listing
May 2020

Acute Eosinophilic Pneumonia Presenting with an Elevated Procalcitonin Level: A Rare Laboratory Finding.

Am J Case Rep 2019 Nov 28;20:1765-1768. Epub 2019 Nov 28.

Department of Pulmonary, Baystate Medical Center, Springfield, MA, USA.

BACKGROUND We present the case of a 33-year-old female who was transferred to a tertiary care hospital because of acute respiratory failure. CASE REPORT History, imaging, and laboratory testing (including an elevated procalcitonin level) were consistent with a diagnosis of bacterial pneumonia. However, despite broad spectrum intravenous antibiotics, her condition worsened. Shortly after transfer to our hospital, she required intubation and mechanical ventilation. Bronchoscopy with bronchoalveolar lavage (BAL) was performed and a diagnosis of acute eosinophilic pneumonia was made. After discontinuation of antibiotics and initiation of steroids she improved quickly. CONCLUSIONS Our case highlights the importance of considering alternative diagnoses in patients who appear to have bacterial lower respiratory tract infection, even in those with elevated procalcitonin levels.
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http://dx.doi.org/10.12659/AJCR.919651DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6900832PMC
November 2019

Study of electric fields of diffraction from spatial light modulator: discussion.

J Opt Soc Am A Opt Image Sci Vis 2019 Oct;36(10):1778-1786

A complete study of electric field vectors and efficiencies of diffraction orders for a phase pattern addressed to a pixelated spatial light modulator (SLM) is discussed here. General mathematical expressions of electric field vectors from SLM are explored here analytically for an arbitrary pattern on SLM with a given input electric field. Using the general expression, we calculate orientations of the electric fields of diffraction for sinusoidal and binary patterns of varying duty cycles. The patterns result in diffracted beams of various orders with different efficiencies calculated analytically and matching well with the experimental results. The binary pattern with 50% duty cycle delivers significant distribution of energies where all the even orders are absent, and the diffraction efficiency of the first-order beam can be close to 40% using an appropriately chosen modulation depth. Using the general expression, it is possible to obtain fields and efficiencies of diffraction for any arbitrary pattern on SLM. The discussion might help researchers using SLM in standard optics experiments.
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http://dx.doi.org/10.1364/JOSAA.36.001778DOI Listing
October 2019

Classification of Micro-Damage in Piezoelectric Ceramics Using Machine Learning of Ultrasound Signals.

Sensors (Basel) 2019 Sep 28;19(19). Epub 2019 Sep 28.

Department of Computer Science, UiT The Arctic University of Norway, 9037 Tromsø, Norway.

Ultrasound based structural health monitoring of piezoelectric material is challenging if a damage changes at a microscale over time. Classifying geometrically similar damages with a difference in diameter as small as 100 μ m is difficult using conventional sensing and signal analysis approaches. Here, we use an unconventional ultrasound sensing approach that collects information of the entire bulk of the material and investigate the applicability of machine learning approaches for classifying such similar defects. Our results show that appropriate feature design combined with simple k-nearest neighbor classifier can provide up to 98% classification accuracy even though conventional features for time-series data and a variety of classifiers cannot achieve close to 70% accuracy. The newly proposed hybrid feature, which combines frequency domain information in the form of power spectral density and time domain information in the form of sign of slope change, is a suitable feature for achieving the best classification accuracy on this challenging problem.
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http://dx.doi.org/10.3390/s19194216DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6806247PMC
September 2019

Cryptogenic adrenal infarction: a rare case of unilateral adrenal infarction in a pregnant woman.

BMJ Case Rep 2019 Mar 27;12(3). Epub 2019 Mar 27.

Baystate Medical Center, University of Massachusetts, Springfield, Massachusetts, USA.

Adrenal infarction is a rare event, especially in pregnancy. The diagnosis is challenging because patients present with acute abdomen and initial workup are usually unrevealing. We present a case of unilateral adrenal infarction in a pregnant young woman without any other causes of thrombophilia, who presented with acute abdominal pain and an unremarkable initial workup. MRI and contrast-enhanced CT scan revealed a non-haemorrhagic infarct of the right adrenal gland. Our case highlights the importance of considering this rare diagnosis in the differential for a pregnant woman with acute abdomen without any obvious surgical cause.
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http://dx.doi.org/10.1136/bcr-2018-228795DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6453374PMC
March 2019

Beyond the Dual Paraneoplastic Syndromes of Small-Cell Lung Cancer with ADH and ACTH Secretion: A Case Report with Literature Review and Future Implications.

Case Rep Oncol Med 2018 18;2018:4038397. Epub 2018 Oct 18.

Department of Medicine, Baystate Medical Center, University of Massachusetts Medical School, Springfield, MA, USA.

We present a case of small-cell lung cancer (SCLC) with syndrome of inappropriate antidiuretic hormone secretion (SIADH) in which serum sodium gradually normalized with the onset of hypertension, refractory hypokalemia, and chloride-resistant metabolic alkalosis due to ectopic adrenocorticotrophic hormone (ACTH) secretion (EAS). In this case report, we discuss the diagnostic challenges of dual paraneoplastic syndromes with SIADH and EAS, management of SCLC with paraneoplastic endocrinopathies, and their prognostic impact on SCLC. In addition, we discuss neuroendocrine differentiation and ectopic hormone production in relation to intratumoral heterogeneity in SCLC and propose tumor microenvironment and hormonal and metabolic dependence as important determinants of tumor growth and survival.
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http://dx.doi.org/10.1155/2018/4038397DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6220734PMC
October 2018

Safety of delayed umbilical cord clamping in preterm neonates of less than 34 weeks of gestation: a randomized controlled trial.

Obstet Gynecol Sci 2018 Nov 29;61(6):655-661. Epub 2018 Oct 29.

Department of Obstetrics and Gynecology, Maulana Azad Medical College and Lok Nayak Hospital, New Delhi, India.

Objective: There is concern regarding the safety of delayed cord clamping (DCC) in babies born at less than 34 weeks' gestation. Therefore, the primary objective of this study was to compare the rates of hyperbilirubinemia and polycythemia during initial 7 days in infants born at less than 34 weeks' gestation and randomized to receive DCC by 120 seconds or early cord clamping (ECC) within less than 30 seconds.

Methods: One hundred pregnant women were randomly subjected to DCC or ECC at the time of birth in a tertiary referral hospital setting. Blood samples were obtained from each newborn at 48 hours and 7 days for hematocrit measurement. Serum bilirubin levels were estimated once the infant had clinically significant jaundice or at 72 hours. For the statistical analysis, the χ test, student's -test, or Wilcoxon rank sum test was used.

Results: The hematocrit was significantly higher in the DCC group than in the ECC group (<0.001). None of the babies had polycythemia. Mean total serum bilirubin level was 6.6 mg/dL in the DCC group and 8.7 mg/dL in the ECC group (<0.001). There was no increased risk of hyperbilirubinemia in the DCC group.

Conclusion: DCC benefits preterm neonates with no significant adverse effects.
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http://dx.doi.org/10.5468/ogs.2018.61.6.655DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6236088PMC
November 2018

Improving quality of care during childbirth in primary health centres: a stepped-wedge cluster-randomised trial in India.

BMJ Glob Health 2018 8;3(5):e000907. Epub 2018 Oct 8.

Western Command Hospital, Panchkula, India.

Background: Low/middle-income countries need a large-scale improvement in the quality of care (QoC) around the time of childbirth in order to reduce high maternal, fetal and neonatal mortality. However, there is a paucity of scalable models.

Methods: We conducted a stepped-wedge cluster-randomised trial in 15 primary health centres (PHC) of the state of Haryana in India to test the effectiveness of a multipronged quality management strategy comprising capacity building of providers, periodic assessments of the PHCs to identify quality gaps and undertaking improvement activities for closure of the gaps. The 21-month duration of the study was divided into seven periods (steps) of 3  months each. Starting from the second period, a set of randomly selected three PHCs (cluster) crossed over to the intervention arm for rest of the period of the study. The primary outcomes included the number of women approaching the PHCs for childbirth and 12 directly observed essential practices related to the childbirth. Outcomes were adjusted with random effect for cluster (PHC) and fixed effect for 'months of intervention'.

Results: The intervention strategy led to increase in the number of women approaching PHCs for childbirth (26 vs 21 women per PHC-month, adjusted incidence rate ratio: 1.22; 95% CI 1.17 to 1.28). Of the 12 practices, 6 improved modestly, 2 remained near universal during both intervention and control periods, 3 did not change and 1 worsened. There was no evidence of change in mortality with a majority of deaths occurring either during referral transport or at the referral facilities.

Conclusion: A multipronged quality management strategy enhanced utilisation of services and modestly improved key practices around the time of childbirth in PHCs in India.

Trial Registration Number: CTRI/2016/05/006963.
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http://dx.doi.org/10.1136/bmjgh-2018-000907DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6195146PMC
October 2018

The Wolf Hidden behind the Clots: Catastrophic Antiphospholipid Antibody Syndrome.

Case Rep Med 2018 19;2018:4693037. Epub 2018 Jul 19.

Department of Medicine, Baystate Medical Center, University of Massachusetts Medical School, Springfield, MA, USA.

Catastrophic antiphospholipid syndrome (CAPS) is a rare but highly fatal clinical syndrome that occurs in up to 1% of patients with antiphospholipid syndrome (APS). The diagnosis of CAPS is often delayed because its presentation with multiple organ thromboses can be confused with other thrombotic microangiopathies and severe sepsis. We report a case of CAPS in a patient with APS and systemic lupus erythematosus (SLE) presenting with thrombotic storm precipitated by trauma, cytomegalovirus (CMV) infection, and noncompliance with anticoagulation therapy. Our case reflects the "two-hit hypothesis" of APS in which the presence of antiphospholipid antibodies (first hit) increases the thrombophilic risk, and thromboses take place in the presence of another thrombophilic condition such as CMV infection in our case. In this case review, we discuss the diagnostic challenges and management of CAPS. In clinical practice, we aim to stress the importance of thorough evaluation and management of precipitating events such as infections in addition to timely diagnosis and treatment of this catastrophic clinical entity.
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http://dx.doi.org/10.1155/2018/4693037DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6079609PMC
July 2018

Non-heuristic automatic techniques for overcoming low signal-to-noise-ratio bias of localization microscopy and multiple signal classification algorithm.

Sci Rep 2018 03 21;8(1):4988. Epub 2018 Mar 21.

School of Computer Science and Engineering, Nanyang Technological University, Singapore, Singapore.

Localization microscopy and multiple signal classification algorithm use temporal stack of image frames of sparse emissions from fluorophores to provide super-resolution images. Localization microscopy localizes emissions in each image independently and later collates the localizations in all the frames, giving same weight to each frame irrespective of its signal-to-noise ratio. This results in a bias towards frames with low signal-to-noise ratio and causes cluttered background in the super-resolved image. User-defined heuristic computational filters are employed to remove a set of localizations in an attempt to overcome this bias. Multiple signal classification performs eigen-decomposition of the entire stack, irrespective of the relative signal-to-noise ratios of the frames, and uses a threshold to classify eigenimages into signal and null subspaces. This results in under-representation of frames with low signal-to-noise ratio in the signal space and over-representation in the null space. Thus, multiple signal classification algorithms is biased against frames with low signal-to-noise ratio resulting into suppression of the corresponding fluorophores. This paper presents techniques to automatically debias localization microscopy and multiple signal classification algorithm of these biases without compromising their resolution and without employing heuristics, user-defined criteria. The effect of debiasing is demonstrated through five datasets of invitro and fixed cell samples.
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http://dx.doi.org/10.1038/s41598-018-23374-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5862973PMC
March 2018

Eigen-analysis reveals components supporting super-resolution imaging of blinking fluorophores.

Sci Rep 2017 06 30;7(1):4445. Epub 2017 Jun 30.

School of Computer Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore.

This paper presents eigen-analysis of image stack of blinking fluorophores to identify the components that enable super-resolved imaging of blinking fluorophores. Eigen-analysis reveals that the contributions of spatial distribution of fluorophores and their temporal photon emission characteristics can be completely separated. While cross-emitter cross-pixel information of spatial distribution that permits super-resolution is encoded in two matrices, temporal statistics weigh the contribution of these matrices to the measured data. The properties and conditions of exploitation of these matrices are investigated. Con-temporary super-resolution imaging methods that use blinking for super-resolution are studied in the context of the presented analysis. Besides providing insight into the capabilities and limitations of existing super-resolution methods, the analysis shall help in designing better super-resolution techniques that directly exploit these matrices.
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http://dx.doi.org/10.1038/s41598-017-04544-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5493635PMC
June 2017

Safety of Delayed Umbilical Cord Clamping in Preterm Neonates Less than 34 weeks Gestation.

Indian J Pediatr 2017 05 23;84(5):414. Epub 2017 Jan 23.

Department of Obstetrics and Gynecology, Maulana Azad Medical College, New Delhi, 110002, India.

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http://dx.doi.org/10.1007/s12098-016-2289-6DOI Listing
May 2017

Multiple signal classification algorithm for super-resolution fluorescence microscopy.

Nat Commun 2016 12 9;7:13752. Epub 2016 Dec 9.

Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore.

Single-molecule localization techniques are restricted by long acquisition and computational times, or the need of special fluorophores or biologically toxic photochemical environments. Here we propose a statistical super-resolution technique of wide-field fluorescence microscopy we call the multiple signal classification algorithm which has several advantages. It provides resolution down to at least 50 nm, requires fewer frames and lower excitation power and works even at high fluorophore concentrations. Further, it works with any fluorophore that exhibits blinking on the timescale of the recording. The multiple signal classification algorithm shows comparable or better performance in comparison with single-molecule localization techniques and four contemporary statistical super-resolution methods for experiments of in vitro actin filaments and other independently acquired experimental data sets. We also demonstrate super-resolution at timescales of 245 ms (using 49 frames acquired at 200 frames per second) in samples of live-cell microtubules and live-cell actin filaments imaged without imaging buffers.
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http://dx.doi.org/10.1038/ncomms13752DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5155148PMC
December 2016

Quantitative analysis of effective height of probes in microwave impedance microscopy.

Rev Sci Instrum 2016 Sep;87(9):094701

Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore.

A quantitative approach is used to determine an effective height of probe beyond which the capacitance contribution is not significant in microwave impedance microscopy (MIM). We compare the effective height for three different modes of measurement, i.e., capacitance C(l) (l is the tip-sample distance), derivative of capacitance (C'(l)), and second derivative of capacitance (C″(l)). We discuss the effects of tip geometry and sample properties such as relative permittivity and sample height on the effective height with examples and analyze the implication on the spatial resolution of MIM. Finally, our results are verified by microwave impedance microscopy (MIM) measurement.
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http://dx.doi.org/10.1063/1.4962242DOI Listing
September 2016

Pregnancy at 65, risks and complications.

J Hum Reprod Sci 2016 Apr-Jun;9(2):119-20

Department of Obstetrics and Gynaecology, Lok Nayak Hospital, Maulana Azad Medical College, Delhi, India.

A 65-year-old postmenopausal pregnant woman was referred with antepartum hemorrhage at 29 weeks of gestation. Postadmission diagnosed with chronic hypertension, gestational diabetes mellitus, valvular heart disease, and placenta previa. Her pregnancy was terminated by cesarean delivery at 32 weeks as she had a bout of bleeding per vaginum. Most of the placenta was adherent with no plane of cleavage; therefore, cesarean hysterectomy was performed. Baby birth weight was 1650 g and was shifted to nursery for observation and mother needed Intensive Care Unit care postcesarean. On the 15(th) day, both healthy mother and baby were discharged. Although pregnancy is possible in postmenopausal women with hormone support but the incidence of complications remain very high. It raises a need for developing well-laid guidelines for performing in vitro fertilization in older age group women.
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http://dx.doi.org/10.4103/0974-1208.183507DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4915282PMC
July 2016

Classification of Hyperspectral or Trichromatic Measurements of Ocean Color Data into Spectral Classes.

Sensors (Basel) 2016 Mar 22;16(3). Epub 2016 Mar 22.

Singapore-MIT Alliance for Research and Technology, Singapore 138602, Singapore.

We propose a method for classifying radiometric oceanic color data measured by hyperspectral satellite sensors into known spectral classes, irrespective of the downwelling irradiance of the particular day, i.e., the illumination conditions. The focus is not on retrieving the inherent optical properties but to classify the pixels according to the known spectral classes of the reflectances from the ocean. The method compensates for the unknown downwelling irradiance by white balancing the radiometric data at the ocean pixels using the radiometric data of bright pixels (typically from clouds). The white-balanced data is compared with the entries in a pre-calibrated lookup table in which each entry represents the spectral properties of one class. The proposed approach is tested on two datasets of in situ measurements and 26 different daylight illumination spectra for medium resolution imaging spectrometer (MERIS), moderate-resolution imaging spectroradiometer (MODIS), sea-viewing wide field-of-view sensor (SeaWiFS), coastal zone color scanner (CZCS), ocean and land colour instrument (OLCI), and visible infrared imaging radiometer suite (VIIRS) sensors. Results are also shown for CIMEL's SeaPRISM sun photometer sensor used on-board field trips. Accuracy of more than 92% is observed on the validation dataset and more than 86% is observed on the other dataset for all satellite sensors. The potential of applying the algorithms to non-satellite and non-multi-spectral sensors mountable on airborne systems is demonstrated by showing classification results for two consumer cameras. Classification on actual MERIS data is also shown. Additional results comparing the spectra of remote sensing reflectance with level 2 MERIS data and chlorophyll concentration estimates of the data are included.
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http://dx.doi.org/10.3390/s16030413DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4813988PMC
March 2016

Contrasting Roles of Islet Resident Immunoregulatory Macrophages and Dendritic Cells in Experimental Autoimmune Type 1 Diabetes.

PLoS One 2016 4;11(3):e0150792. Epub 2016 Mar 4.

Department of Medicine, Harvard Medical School and the Transplant Institute at Beth Israel Deaconess Medical Center, Boston, Massachusetts, 02215, United States of America.

The innate immune system critically shapes diabetogenic adaptive immunity during type 1 diabetes (T1D) pathogenesis. While the role of tissue-infiltrating monocyte-derived macrophages in T1D is well established, the role of their tissue-resident counterparts remains undefined. We now demonstrate that islet resident macrophages (IRMs) from non-autoimmune mice have an immunoregulatory phenotype and powerfully induce FoxP3+ Tregs in vitro. The immunoregulatory phenotype and function of IRMs is compromised by TLR4 activation in vitro. Moreover, as T1D approaches in NOD mice, the immunoregulatory phenotype of IRMs is diminished as is their relative abundance compared to immunostimulatory DCs. Our findings suggest that maintenance of IRM abundance and their immunoregulatory phenotype may constitute a novel therapeutic strategy to prevent and/or cure T1D.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0150792PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4778921PMC
July 2016

Multi-resolution subspace-based optimization method for solving three-dimensional inverse scattering problems.

J Opt Soc Am A Opt Image Sci Vis 2015 Nov;32(11):2218-26

An innovative methodology is proposed to solve quantitative three-dimensional microwave imaging problems formulated within the contrast source framework. The introduced technique is based on the combination of an efficient iterative multiscaling strategy aimed at mitigating local minimum issue arising in inverse scattering problems, and a local search algorithm based on the subspace-based optimization method (SOM) devoted to effectively retrieving both the "deterministic" and the "ambiguous" parts of the unknown contrast currents. To achieve this goal, a nested iteration process is adopted in which the outer loop iteratively refines the region of interest (ROI) where the scatterers are detected, while the inner loop retrieves the dielectric properties of the scatterers within the ROIs. Selected numerical examples are also given to show the validity and robustness of the proposed algorithm in comparison with state-of-the-art techniques.
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http://dx.doi.org/10.1364/JOSAA.32.002218DOI Listing
November 2015

Biomolecular inflammatory response to surgical energy usage in laparoscopic surgery: results of a randomized study.

Surg Endosc 2016 05 21;30(5):1733-41. Epub 2015 Jul 21.

Department of Anatomy, Lady Hardinge Medical College, New Delhi, India.

Objective: Use of surgical energy is integral to laparoscopic surgery (LS). Energized dissection (ED) has a potential to impact the biomolecular expression of inflammation due to ED-induced collateral inflammation. We did this triple-blind randomized controlled (RCT) study to assess this biomolecular footprint in an index LS, i.e., laparoscopic cholecystectomy (LC).

Methods And Procedures: This RCT was conducted in collaboration with tertiary-level institutions, from January 2014 to December 2014 with institutional review board clearance. Consecutive, unselected, consenting candidates for LC were randomized (after anesthesia induction) into group I (ED) and group II (non-ED). They were managed with compliance to universal protocols for ethics, informed consent, anesthesia, drug usage and clinical pathway with blinded observers. Biomolecular inflammatory markers, i.e., interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α) and highly sensitive CRP (HS-CRP), were measured with blood drawn juxta-preoperatively (H0), at 4 h (H4) and at 24 h (H24). The quantitative changes induced by ED on IL-6, TNF-α and HS-CRP at H0, H4 and H24 with their kinetic behavior were the study endpoint. Prospective data were analyzed statistically with a p value of <0.05 being significant.

Results: Two cases from the ED group had biliary injury and hence were withdrawn from analysis. The ED (n = 49) and non-ED (n = 51) groups had similar demographic, clinical and H0 biomolecular variables. There was a significant increase in IL-6, TNF-α and HS-CRP from H0 to H4 in both the groups (p values <0.001). From H4 to H24, all three cytokines showed significant increase in ED group (p < 0.05), whereas in the non-ED group, IL-6 showed significant fall (p = 0.004) and TNF-α showed no significant change (p = 0.063). Both the groups showed H4-H24 elevation of HS-CRP (p = 0.000).

Conclusion: Energized dissection adds to the cytokine-mediated postoperative inflammation. The additional ED-induced inflammation can be measured objectively by IL-6 and TNF-α levels.

Clinical Trials Registry: Clinical Trials Registry, India (REF/2014/06/007153).
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http://dx.doi.org/10.1007/s00464-015-4408-2DOI Listing
May 2016

Feature-based filter design for resolution enhancement of known features in microscopy.

J Opt Soc Am A Opt Image Sci Vis 2014 Dec;31(12):2610-7

We present a new feature-based design concept for filter design in which a filter is designed specifically to image a known feature with dimensions lower than the optical resolution of the system. Unlike the conventional filter design based on focal spot engineering, we use the complete response of the microscope to form a resolution factor and consider minimizing the resolution factor as the design goal. We consider three design goals (i.e., resolution factors) based on the system response and show that a feature matching approach is more suitable in practice. It is shown that a three-bar pattern and grid of square dots of critical dimension, 0.08λ, can be resolved using a simple two-layer feature-based filter designed for radially polarized illumination in aplanatic solid immersion lens microscopy. An example that requires a more complex filter is also shown. Applicability of the concept of feature-based filter design in diverse microscopy scenarios is discussed as well.
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http://dx.doi.org/10.1364/JOSAA.31.002610DOI Listing
December 2014

Outcomes of laparoscopic cholecystectomy done with surgical energy versus done without surgical energy: a prospective-randomized control study.

Surg Endosc 2014 Nov 31;28(11):3059-67. Epub 2014 May 31.

Department of General and Laparoscopic Surgery, Ganga Ram Institute of Post Graduate Medical Education and Research (GRIPMER), New Delhi, India,

Objective: Laparoscopic cholecystectomy (LC), a gold standard procedure can be done without energized dissection (ED). We did a randomized study for the outcomes of LC done with ED or without ED, i.e., with cold dissection (CD).

Methods And Procedures: At a tertiary level institution, open-ended prospective-randomized control study was conducted between September 2008 and June 2013. Consecutive, unselected, consenting candidates for LC were enrolled following standard ethics, informed consent, anesthesia, and clinical pathway protocol. They were allocated to control group (LC with ED) or study group (LC with CD, as per our published technique with the option for rescue ED). The study points were based upon Clavien-Dindo grading of postoperative complications. They were either, peri-operative events potentially affecting, hospital stay (Grade I) or Grade II-V, e.g., peri-operative hemodynamic instability, needing intervention/blood transfusion, injury to biliary ducts/hollow viscous, postoperative biliary leak, postoperative re-intervention, re-hospitalization, mortality, and any adverse event during a 90-day follow-up period. The data were prospectively collected in an integrated "hospital information system" that could be retrieved only by independent external coordinators.

Results: Demographics, co-morbidities, and gallbladder inflammation profile of the control group (n = 361) and study group (n = 384) were comparable. There was no rescue ED usage in the study group. Hospital stay (Grade I adverse outcome dependent) was longer, i.e., 1.6 ± 1.03 in the control versus 1.35 ± 1.2 days in the study group (p < 0.001). Grade II-IV complications were significantly more (p < 0.009) in control group. There was one common bile duct (CBD) injury in each group. The index bilio-enteric anastomosis for CBD injury in control group failed and needed a revision with multiple interventions. There was one grade V adverse outcome, i.e., mortality in the control group.

Conclusion: Avoiding the use of ED in LC is associated with better outcomes.
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http://dx.doi.org/10.1007/s00464-014-3579-6DOI Listing
November 2014
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