Feasibility and Implementation of Ex Vivo Fluorescence Confocal Microscopy for Diagnosis of Oral Leukoplakia: Preliminary Study

Background: Oral leukoplakia is a potentially malignant lesion with a clinical impression similar to different benign and malignant lesions. Ex vivo fluorescence confocal microscopy is a developing approach for a rapid “chairside” detection of oral lesions with a cellular-level resolution. A possible application of interest is a quick differentiation of benign oral pathology from normal or cancerous tissue. The aim of this study was to analyze the sensitivity and specificity of ex vivo fluorescence confocal microscopy (FCM) for detecting oral leukoplakia and to compare confocal images with gold-standard histopathology. Methods: Imaging of 106 submosaics of 27 oral lesions was performed using an ex vivo fluorescence confocal microscope immediately after excision. Every confocal image was qualitatively assessed for presence or absence of leukoplakia by an expert reader of confocal images. The results were compared to conventional histopathology with H&E staining. Results: Leukoplakia was detected with an overall sensitivity of 96.3%, specificity of 92.3%, positive predictive value of 93%, and negative predictive value of 96%. Conclusion: The results demonstrate the potential of ex vivo confocal microscopy in fresh tissue for rapid real-time assessment of oral pathologies.

Optical Characterization of Sodium Fluorescein In Vitro and Ex Vivo

Objective

The utilization of fluorescein-guided biopsies and resection has been recently discussed as a suitable strategy to improve and expedite operative techniques for the resection of central nervous system (CNS) tumors. However, little is known about the optical properties of sodium fluorescein (NaFl) in human tumor tissue and their potential impact on ex vivo analyses involving fluorescence-based methods.

Methods

Tumor tissue was obtained from a study cohort of an observational study on the utilization of fluorescein-guided biopsy and resection (n=5). The optical properties of fluorescein-stained tissue were compared to the optical features of the dye in vitro and in control samples consisting of tumor tissue of high-grade glioma patients (n=3) without intravenous (i.v.) application of NaFl. The dye-exposed tumor tissues were used for optical measurements to confirm the detectability of NaFl emission ex vivo. The tissue samples were fixed in 4%PFA, immersed in 30% sucrose, embedded in Tissue-Tek OCT compound, and cut to 10 μm cryosections. Spatially resolved emission spectra from tumor samples were recorded on representative slides with a Confocal Laser Scanning Microscope FV1000 (Olympus GmbH, Hamburg, Germany) upon excitation with λ_exc = 488 nm.

Results

Optical measurements of fluorescein in 0.9% sodium chloride (NaCl) under in vitro conditions showed an absorption maximum of λ_{max abs} = 479 nm as detected with spectrophotometer Specord 200 and an emission peak at λ_{max em} = 538 nm recorded with the emCCD detection system of a custom-made microscope-based single particle setup using a 500 nm long-pass filter. Further measurements revealed pH- and concentration-dependent emission spectra of NaFl. Under ex vivo conditions, confocal laser scanning microscopy of fluorescein tumor samples revealed a slight bathochromic shift and a broadening of the emission band.

Conclusion

Tumor uptake of NaFl leads to changes in the optical properties – a bathochromic shift and broadening of the emission band – possibly caused by the dye’s high pH sensitivity and concentration-dependent reabsorption acting as an inner filter of the dye’s emission, particularly in the short wavelength region of the emission spectrum where absorption and fluorescence overlap. Understanding the ex vivo optical properties of fluorescein is crucial for testing and validating its further applicability as an optical probe for intravital microscopy, immunofluorescence localization studies, and flow cytometry analysis.

Validation of a Novel Confocal Microscopy Imaging Protocol With Assessment of Reproducibility and Comparison of Nerve Metrics in Dry Eye Disease Compared With Controls

PURPOSE

The purposes of this study were to assess the reproducibility of a novel standardized technique for capturing corneal subbasal nerve plexus images with in vivo corneal confocal microscopy and to compare nerve metrics captured with this method in participants with dry eye and control participants.

METHODS

Cases and controls were recruited based on their International Statistical Classification of Diseases and Related Health Problems (ICD-10) diagnoses. Participants completed the following 3 ocular symptom questionnaires: the Ocular Surface Disease Index, Neuropathic Pain Symptom Inventory, and Dry Eye Questionnaire 5. A novel eye fixation-grid system was used to capture 30 standardized confocal microscopy images of the central cornea. Each participant was imaged twice by different operators. Seven quantitative nerve metrics were analyzed using automated software (ACCmetrics, Manchester, United Kingdom) for all 30 images and a 6-image subset.

RESULTS

Forty-seven participants were recruited (25 classified as dry eye and 22 controls). The most reproducible nerve metrics were corneal nerve fiber length [intraclass correlation (ICC) = 0.86], corneal nerve fiber area (ICC = 0.86), and fractal dimension (ICC = 0.90). Although differences were not statistically significant, all mean nerve metrics were lower in those with dry eye compared with controls. Questionnaire scores did not significantly correlate with nerve metrics. Reproducibility of nerve metrics was similar when comparing the entire 30-image montage to a central 6-image subset.

CONCLUSIONS

A standardized confocal imaging technique coupled with quantitative assessment of corneal nerves produced reproducible corneal nerve metrics even with different operators. No statistically significant differences in in vivo corneal confocal microscopy nerve metrics were observed between participants with dry eye and control participants.

Antibacterial Activity of Positively and Negatively Charged Hematite (α-Fe2O3) Nanoparticles to Escherichia coli, Staphylococcus aureus and Vibrio fischeri

In the current study, the antibacterial activity of positively and negatively charged spherical hematite (α-Fe2O3) nanoparticles (NPs) with primary size of 45 and 70 nm was evaluated against clinically relevant bacteria Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive) as well as against naturally bioluminescent bacteria Vibrio fischeri (an ecotoxicological model organism). α-Fe2O3 NPs were synthesized using a simple green hydrothermal method and the surface charge was altered via citrate coating. To minimize the interference of testing environment with NP's physic-chemical properties, E. coli and S. aureus were exposed to NPs in deionized water for 30 min and 24 h, covering concentrations from 1 to 1000 mg/L. The growth inhibition was evaluated following the postexposure colony-forming ability of bacteria on toxicant-free agar plates. The positively charged α-Fe2O3 at concentrations from 100 mg/L upwards showed inhibitory activity towards E. coli already after 30 min of contact. Extending the exposure to 24 h caused total inhibition of growth at 100 mg/L. Bactericidal activity of positively charged hematite NPs against S. aureus was not observed up to 1000 mg/L. Differently from positively charged hematite NPs, negatively charged citrate-coated α-Fe2O3 NPs did not exhibit any antibacterial activity against E. coli and S. aureus even at 1000 mg/L. Confocal laser scanning microscopy and flow cytometer analysis showed that bacteria were more tightly associated with positively charged α-Fe2O3 NPs than with negatively charged citrate-coated α-Fe2O3 NPs. Moreover, the observed associations were more evident in the case of E. coli than S. aureus, being coherent with the toxicity results. Vibrio fischeri bioluminescence inhibition assays (exposure medium 2% NaCl) and colony forming ability on agar plates showed no (eco)toxicity of α-Fe2O3 (EC50 and MBC > 1000 mg/L).

Tinea pedis in a child: How reflectance confocal microscopy can help in diagnosis of dermatophytosis

A 7-year-old girl presented with a hyperkeratotic scale on the plantar surface of her left foot. A microscopic potassium hydroxide examination was performed and negative. Reflectance confocal microscopy was performed showing fungal hyphae and an inflammatory infiltrate confirming a diagnosis of tinea pedis.

Visualization of brain microvasculature and blood flow in vivo: Feasibility study using confocal laser endomicroscopy

OBJECTIVE

Qualitative and quantitative analyses of blood flow in normal and pathologic brain and spinal cord microvasculature were performed using confocal laser endomicroscopy (CLE).

METHODS

Blood flow in cortical, dural, and spinal cord microvasculature was assessed in vivo in swine. We assessed microvasculature under normal conditions and after vessel occlusion, brain injury due to cold or surgical trauma, and cardiac arrest. Tumor-associated microvasculature was assessed in vivo and ex vivo in 20 patients with gliomas.

RESULTS

We observed erythrocyte flow in vessels 5-500 µm in diameter. Thrombosis, flow arrest and redistribution, flow velocity changes, agglutination, and cells rolling were assessed in normal and injured brain tissue. Microvasculature in in vivo CLE images of gliomas was classified as normal in 68% and abnormal in 32% of vessels on the basis of morphological appearance. Dural lymphatic channels were discriminated from blood vessels. Microvasculature CLE imaging was possible for up to 30 minutes after a 1 mg/kg intravenous dose of fluorescein.

CONCLUSIONS

CLE imaging allows assessment of cerebral and tumor microvasculature and blood flow alterations with subcellular resolution intraoperative imaging demonstrating precise details of real-time cell movements. Research and clinical scenarios may benefit from this novel intraoperative in vivo microscopic fluorescence imaging modality.

Spatial Correlations and Distribution of Competence Gene Expression in Biofilms of Streptococcus mutans

Streptococcus mutans is an important pathogen in the human oral biofilm. It expresses virulent behaviors that are linked to its genetic competence regulon, which is controlled by comX. Expression of comX is modulated by two diffusible signaling peptides, denoted CSP and XIP, and by other environmental cues such as pH and oxidative stress. The sensitivity of S. mutans competence to environmental inputs that may vary on microscopic length scales raises the question of whether the biofilm environment creates microniches where competence and related phenotypes are concentrated, leading to spatial clustering of S. mutans virulence behaviors. We have used two-photon microscopy to characterize the spatial distribution of comX expression among individual S. mutans cells in biofilms. By analyzing correlations in comX activity, we test for spatial clustering that may suggest localized competence microenvironments. Our data indicate that both competence-signaling peptides diffuse efficiently through the biofilm. XIP elicits a population-wide response. CSP triggers a Poisson-like, spatially random comX response from a subpopulation of cells that is homogeneously dispersed. Our data indicate that competence microenvironments if they exist are small enough that the phenotypes of individual cells are not clustered or correlated to any greater extent than occurs in planktonic cultures.

Preoperative Evaluation through Dermoscopy and Reflectance Confocal Microscopy of the Lateral Excision Margins for Primary Basal Cell Carcinoma

Complete removal of malignant skin lesions with minimal impact on the aesthetic and functional aspects is the ideal of every dermatologic surgeon. Incomplete surgical excisions and tumor recurrences of basal cell carcinomas (BCC) commonly occur due to the subclinical extension of tumor lateral margins. Presently, the lateral excision margins for BCC cannot be objectively assessed preoperatively, dermoscopy proving to be relatively inefficient in this respect. The question is whether BCC lateral excision margins can be precisely determined preoperatively through the use of complementary non-invasive imaging techniques such as dermoscopy and reflectance confocal microscopy (RCM), thus permitting the complete removal of the lesion in a single stage, estimation of the post-excisional defect, and planning an appropriate reconstruction, especially in medical centers where Mohs micrographic surgery is not available. We present the results of a prospective, histopathologically controlled study designed to determine the feasibility of preoperative, non-invasive, in vivo evaluation of the lateral excision margins for primary basal cell carcinoma, through dermoscopy and RCM.

Adipose Tissue-Derived Mesenchymal Stem Cell Concentrated Conditioned Medium Alters the Expression Pattern of Glutamate Regulatory Proteins and Aquaporin-4 in the Retina after Mild Traumatic Brain Injury

Concentrated conditioned media from adipose tissue-derived mesenchymal stem cells (ASC-CCM) show promise for retinal degenerative diseases. In this study, we hypothesized that ASC-CCM could rescue retinal damage and thereby improve visual function by acting through Müller glia in mild traumatic brain injury (mTBI). Adult C57Bl/6 mice were subjected to a 50-psi air pulse on the left side of the head, resulting in an mTBI. After blast injury, 1 μL (∼100 ng total protein) of human ASC-CCM was delivered intravitreally and followed up after 4 weeks for visual function assessed by electroretinogram and histopathological markers for Müller cell-related markers. Blast mice that received ASC-CCM, compared with blast mice that received saline, demonstrated a significant improvement in a- and b-wave response correlated with a 1.3-fold decrease in extracellular glutamate levels and a concomitant increase in glutamine synthetase (GS), as well as the glutamate transporter (GLAST) in Müller cells. Additionally, an increase in aquaporin-4 (AQP4) in Müller cells in blast mice received saline restored to normal levels in blast mice that received ASC-CCM. In vitro studies on rMC-1 Müller glia exposed to 100 ng/mL glutamate or RNA interference knockdown of GLAST expression mimicked the increased Müller cell glial fibrillary acidic protein (a marker of gliosis) seen with mTBI, and suggested that an increase in glutamate and/or a decrease in GLAST might contribute to the Müller cell activation in vivo. Taken together, our data suggest a novel neuroprotective role for ASC-CCM in the rescue of the visual deficits and pathologies of mTBI via restoration of Müller cell health.

Ex Vivo Fluorescein-Assisted Confocal Laser Endomicroscopy (CONVIVO® System) in Patients With Glioblastoma: Results From a Prospective Study

Background

Confocal laser endomicroscopy (CLE) allowing intraoperative near real-time high-resolution cellular visualization is a promising method in neurosurgery. We prospectively tested the accuracy of a new-designed miniatured CLE (CONVIVO® system) in giving an intraoperative first-diagnosis during glioblastoma removal.

Methods

Between January and May 2018, 15 patients with newly diagnosed glioblastoma underwent fluorescein-guided surgery. Two biopsies from both tumor central core and margins were harvested, dividing each sample into two specimens. Biopsies were firstly intraoperatively ex vivo analyzed by CLE, subsequently processed for frozen and permanent fixation, respectively. Then, a blind comparison was conducted between CLE and standard permanent section analyses, checking for CLE ability to provide diagnosis and categorize morphological patterns intraoperatively.

Results

Blindly comparing CONVIVO® and frozen sections images we obtained a high rate of concordance in both providing a correct diagnosis and categorizing patterns at tumor central core (80 and 93.3%, respectively) and at tumor margins (80% for both objectives). Comparing CONVIVO® and permanent sections, concordance resulted similar at central core (total/partial concordance in 80 and 86.7% for diagnosis and morphological categorization, respectively) and lower at tumor margins (66.6% for both categories). Time from fluorescein injection and time from biopsy sampling to CONVIVO® scanning was 134 ± 31 min (122–214 min) and 9.23 min (1–17min), respectively. Mean time needed for CONVIVO® images interpretation was 5.74 min (1–7 min).

Conclusions

The high rate of diagnostic/morphological consistency found between CONVIVO® and frozen section analyses suggests the possibility to use CLE as a complementary tool for intraoperative diagnosis of ex vivo tissue specimens during glioblastoma surgery.

Ex Vivo Murine Skin Model for B. burgdorferi Biofilm

Borrelia burgdorferi, the causative agent of Lyme disease, has been recently shown to form biofilm structures in vitro and in vivo. Biofilms are tightly clustered microbes characterized as resistant aggregations that allow bacteria to withstand harsh environmental conditions, including the administration of antibiotics. Novel antibiotic combinations have recently been identified for B. burgdorferi in vitro, however, due to prohibiting costs, those agents have not been tested in an environment that can mimic the host tissue. Therefore, researchers cannot evaluate their true effectiveness against B. burgdorferi, especially its biofilm form. A skin ex vivo model system could be ideal for these types of experiments due to its cost effectiveness, reproducibility, and ability to investigate host-microbial interactions. Therefore, the main goal of this study was the establishment of a novel ex vivo murine skin biopsy model for B. burgdorferi biofilm research. Murine skin biopsies were inoculated with B. burgdorferi at various concentrations and cultured in different culture media. Two weeks post-infection, murine skin biopsies were analyzed utilizing immunohistochemical (IHC), reverse transcription PCR (RT-PCR), and various microscopy methods to determine B. burgdorferi presence and forms adopted as well as whether it remained live in the skin tissue explants. Our results showed that murine skin biopsies inoculated with 1 × 107 cells of B. burgdorferi and cultured in BSK-H + 6% rabbit serum media for two weeks yielded not just significant amounts of live B. burgdorferi spirochetes but biofilm forms as well. IHC combined with confocal and atomic force microscopy techniques identified specific biofilm markers and spatial distribution of B. burgdorferi aggregates in the infected skin tissues, confirming that they are indeed biofilms. In the future, this ex vivo skin model can be used to study development and antibiotic susceptibility of B. burgdorferi biofilms in efforts to treat Lyme disease effectively.

Individual cell motion in healthy human skin microvasculature by reflectance confocal video microscopy

OBJECTIVE

To describe upper dermal microvasculature of healthy human skin in terms of density and size of cutaneous blood vessels, leukocyte velocity, and leukocyte interactions with the endothelium.

METHODS

We used a reflectance confocal microscope, the VivaScope 1500, to acquire videos of individual cell motion.

RESULTS

We found no rolling leukocytes in the upper microvasculature of ten healthy subjects. We observed "paused" leukocytes, that is, leukocytes that temporarily stop, coinciding with the simultaneous stopping of the rest of the blood flow. We imaged more paused (median: 1.0 per subject) and adherent (1.5) leukocytes in the forearm than in the chest (median 0 paused and 0 adherent per subject) per 5 minutes of videos per body site. Leukocytes were paused for a median of 7 seconds in the forearm and 3 seconds in the chest, and we found no correlation between this parameter and the blood vessel or leukocyte size. We visualized blood flow change direction. Flowing leukocyte velocities followed a lognormal distribution and were on average higher in the chest (117 µm/s) than in the forearm (66 µm/s).

CONCLUSION

The proposed method and reported values in healthy skin provide new insights into intact human skin microcirculation.

Gingipain R1 and Lipopolysaccharide From Porphyromonas gingivalis Have Major Effects on Blood Clot Morphology and Mechanics

Background:Porphyromonas gingivalis and its inflammagens are associated with a number of systemic diseases, such as cardiovascular disease and type 2 diabetes (T2DM). The proteases, gingipains, have also recently been identified in the brains of Alzheimer's disease patients and in the blood of Parkinson's disease patients. Bacterial inflammagens, including lipopolysaccharides (LPSs) and various proteases in circulation, may drive systemic inflammation.

Methods: Here, we investigate the effects of the bacterial products LPS from Escherichia coli and Porphyromonas gingivalis, and also the P. gingivalis gingipain [recombinant P. gingivalis gingipain R1 (RgpA)], on clot architecture and clot formation in whole blood and plasma from healthy individuals, as well as in purified fibrinogen models. Structural analysis of clots was performed using confocal microscopy, scanning electron microscopy, and AFM-Raman imaging. We use thromboelastography® (TEG®) and rheometry to compare the static and dynamic mechanical properties of clots.

Results: We found that these inflammagens may interact with fibrin(ogen) and this interaction causes anomalous blood clotting.

Conclusions: These techniques, in combination, provide insight into the effects of these bacterial products on cardiovascular health, and particularly clot structure and mechanics.

From 2D to 3D: Promising Advances in Imaging Lung Structure

The delicate structure of murine lungs poses many challenges for acquiring high-quality images that truly represent the living lung. Here, we describe several optimized procedures for obtaining and imaging murine lung tissue. Compared to traditional paraffin cross-section and optimal cutting temperature (OCT), agarose-inflated vibratome sections (aka precision-cut lung slices), combines comparable structural preservation with experimental flexibility. In particular, we discuss an optimized procedure to precision-cut lung slices that can be used to visualize three-dimensional cell-cell interactions beyond the limitations of two-dimensional imaging. Super-resolution microscopy can then be used to reveal the fine structure of lung tissue's cellular bodies and processes that regular confocal cannot. Lastly, we evaluate the entire lung vasculature with clearing technology that allows imaging of the entire volume of the lung without sectioning. In this manuscript, we combine the above procedures to create a novel and evolutionary method to study cell behavior ex vivo, trace and reconstruct pulmonary vasculature, address fundamental questions relevant to a wide variety of vascular disorders, and perceive implications to better imaging clinical tissue.

Case Report: Chilblains-like lesions (COVID-19 toes) during the pandemic - is there a diagnostic window?

The COVID-19 outbreak caused by the novel coronavirus, SARS-CoV-2, typically presents with symptoms including fever, cough, headache, myalgia, asthenia, anosmia, diarrhea, and sometimes pneumonia, which can be fatal.  Recently, new dermatologic findings have been described in association with the disease that can potentially be a distinguishing feature of infection. One such feature resembles chilblains and this case report represents a presentation of this feature with a 48-year-old female with violaceous lesions with surrounding pink erythema on her toes who tested negative for COVID-19.

Case Report: Cutaneous chilblains-like lesions (CCLL) versus COVID-19 toes during the pandemic. Confocal findings and proposal for new acronym, CCLL - is there a diagnostic window?

The COVID-19 outbreak caused by the novel coronavirus, SARS-CoV-2, typically presents with symptoms including fever, cough, headache, myalgia, asthenia, anosmia, diarrhea, and sometimes pneumonia, which can be fatal.  Recently, new dermatologic findings have been described in association with the disease that can potentially be a distinguishing feature of infection. One such feature resembles chilblains and this case report represents a unique presentation of this feature.

Implementation and Optimization of a Dual-confocal Autofocusing System

This paper describes the implementation and optimization of a dual-confocal autofocusing system that can easily describe a real-time position by measuring the response signal (i.e., intensity) of the front and the rear focal points of the system. This is a new and systematic design strategy that would make it possible to use this system for other applications while retrieving their characteristic curves experimentally; there is even a good chance of this technique becoming the gold standard for optimizing these dual-confocal configurations. We adopt two indexes to predict our system performance and discover that the rear focal position and its physical design are major factors. A laboratory-built prototype was constructed and demonstrated to ensure that its optimization was valid. The experimental results showed that a total optical difference from 150 to 400 mm significantly affected the effective volume of our designed autofocusing system. The results also showed that the sensitivity of the dual-confocal autofocusing system is affected more by the position of the rear focal point than the position of the front focal point. The final optimizing setup indicated that the rear focal length and the front focal length should be set at 200 and 100 mm, respectively. In addition, the characteristic curve between the focus error signal and its position could successfully define the exact position by a polynomial equation of the sixth order, meaning that the system can be straightforwardly applied to an accurate micro-optical auto-focusing system.

Use of Target-Specific Liposome and Magnetic Nanoparticle Conjugation for the Amplified Detection of Norovirus

Viral diseases are one of the most life-threatening diseases as they can erupt unpredictably and spread rapidly in any medium with a very small number of particles. Therefore, the key for lethal virus detection should be highly sensitive in the early-stage detection, which can help increase the chance of survival. Amplification of the detecting signal is one of the most promising mechanisms for the detection of low-concentration analytes. A proper amplification can develop such a kind of system where a small number of particles can produce intense signals for a prominent detection. Keeping this in mind, in this report, we have presented a fluorometric method to detect norovirus (NoV) by a newly developed fluorophore-labeled liposome and a magnetically modified Fe₃O₄ combined system. Homogeneously distributed amine-functionalized liposomes have been constructed filled with a strong fluorophore of calcein. Simultaneously, (3-aminopropyl)-triethoxysilane (APTES)-functionalized Fe₃O₄ nanoparticles are also synthesized by the standard silanization process, and these two separately synthesized nanoparticles were functionalized with an antibody to achieve specificity. The Fe₃O₄ and calcein-liposome system has been applied for NoV detection, which was magnetically separated from the analyte medium and then externally burst to release the fluorophores from the core of the liposome. The easiness, rapidity, and sensitivity in a wide linear range can offer a huge potential of this method in point-of-care diagnostics.

Imaging flowers: a guide to current microscopy and tomography techniques to study flower development

Developmental biology relies heavily on our ability to generate three-dimensional images of live biological specimens through time, and to map gene expression and hormone response in these specimens as they undergo development. The last two decades have seen an explosion of new bioimaging technologies that have pushed the limits of spatial and temporal resolution and provided biologists with invaluable new tools. However, plant tissues are difficult to image, and no single technology fits all purposes; choosing between many bioimaging techniques is not trivial. Here, we review modern light microscopy and computed projection tomography methods, their capabilities and limitations, and we discuss their current and potential applications to the study of flower development and fertilization.

Antiproliferative Effects of Roylea cinerea (D. Don) Baillon Leaves in Immortalized L6 Rat Skeletal Muscle Cell Line: Role of Reactive Oxygen Species Mediated Pathway

Roylea cinerea (D. Don) Baill. (Lamiaceae) is an indigenous plant of Western Himalayas, and has been used by the native population for the treatment of various diseases such as fever, malaria, diabetes, jaundice, and skin ailments. However, limited proportion of pharmacological and toxicological information is available on the bioactive properties of this plant. Therefore, the present study was designed to explore the anti-oxidant and anti-proliferative activities of Roylea cinerea. Methanolic extracts of leaves and stem of Roylea cinerea were prepared through maceration procedure and evaluated for the antioxidant activity using hydrogen/electron donating and hydroxyl radical scavenging assay. Significant antioxidant activity was observed for the methanolic extract of leaves in DPPH (EC₅₀ 239 µg/ml), molybdate ion reduction assay (29.73 µg ascorbic acid equivalent/mg dry weight of extract) as well as in plasmid nicking assay. Anti-proliferative and apoptotic activity in L6 rat skeletal muscle cell line was done using in vitro assays, i.e., MTT, Lactate dehydrogenase, mitochondrial membrane potential assay along with phase contrast, confocal, and scanning electron microscopy. The methanol extract of leaves and stem inhibited the growth of L6 cells with IC₅₀ value of 69.41µg/ml and 124.93 µg/ml, respectively, and the lactate dehydrogenase activity was 20.29% and 0.3%, respectively. Cell cycle analysis by flow cytometry exhibited the arrest of cells in G1 and sub-G1 phase by methanolic leaves extract. Furthermore, the results of microscopic and docking analysis strengthened the observation made in the present study regarding the apoptotic mode of cell death in the L6 cell line. The in vitro findings of our studies revealed that the bioactive ingredients present in the methanolic extract of leaves and stem of Roylea cinerea have the anticancer potential. Further in vivo studies are needed to verify the in vitro results.

Characterizing Single-Molecule Conformational Changes Under Shear Flow with Fluorescence Microscopy

Single-molecule behavior under mechanical perturbation has been characterized widely to understand many biological processes. However, methods such as atomic force microscopy have limited temporal resolution, while Förster resonance energy transfer (FRET) only allow conformations to be inferred. Fluorescence microscopy, on the other hand, allows real-time in situ visualization of single molecules in various flow conditions. Our protocol describes the steps to capture conformational changes of single biomolecules under different shear flow environments using fluorescence microscopy. The shear flow is created inside microfluidic channels and controlled by a syringe pump. As demonstrations of the method, von Willebrand factor (VWF) and lambda DNA are labeled with biotin and fluorophore and then immobilized on the channel surface. Their conformations are continuously monitored under variable shear flow using total internal reflection (TIRF) and confocal fluorescence microscopy. The reversible unraveling dynamics of VWF are useful for understanding how its function is regulated in human blood, while the conformation of lambda DNA offers insights into the biophysics of macromolecules. The protocol can also be widely applied to study the behavior of polymers, especially biopolymers, in varying flow conditions and to investigate the rheology of complex fluids.

Controlling Shapes in a Coaxial Flow Focusing Microfluidic Device: Experiments and Theory

A coaxial flow focusing PDMS (polydimethylsiloxane) microfluidic device has been designed and manufactured by soft lithography in order to experimentally study a miscible inner flow. We studied a coaxially focused inner flow (formed by an aqueous fluorescein solution) which was fully isolated from all microchannel surfaces by an additional water outer flow. Different flow rates were used to produce a variety of flow ratios and a 3D reconstruction of the cross-section was performed using confocal microscope images. The results showed an elliptical section of the coaxially focused inner flow that changes in shape depending on the flow rate ratio applied. We have also developed a mathematical model that allows us to predict and control the geometry of the coaxially focused inner flow.

Monitoring of intracellular localization of Hepatitis B virus P22 protein using Laser Scanning Confocal Microscopy and Airyscan

The aim of this study was to assess nucleo-cytoplasmic protein localization to better understand the exact intracellular localization of viral proteins involved with infections. Having determined the general protein localization of hepatitis B virus P22 precore protein, the aim was to more specifically resolve its intracellular organization. This was done using both laser scanning microscopy and Airyscan techniques. Using a 63× objective, the resolution obtained with Airyscan was increased by 1.5-fold as compared to confocal microscopy (p value <.00001).