Comparative Study Regarding the Properties of Methylene Blue and Proflavine and Their Optimal Concentrations for In Vitro and In Vivo Applications

Concentration-dependent aggregation of methylene blue acting as a photoredox catalyst

Hydroxylation reactions are important in biological processes and synthetic schemes. Many challenging hydroxylation reactions have been achieved using photoredox catalytic methods. For the oxidative hydroxylation of arylboronic acids, methylene blue has been used successfully as a photoredox catalyst to produce phenyl groups. Here we use broadband transient absorption spectroscopy to determine the mechanism of the photoredox catalytic reaction of methylene blue with phenylboronic acid in the presence of N,N-diisopropylethylamine. Our results show that the reaction proceeds through the triplet state of methylene blue in the presence of oxygen, generating superoxide radical anions. In addition, we observe dimerization of the methylene blue at typical catalytic loadings. As these dimers do not participate in the reaction, increasing the concentration of methylene blue is potentially detrimental to the overall yield.

Pericapsular nerve group block: a 3D CT scan imaging study to determine the spread of injectate

BACKGROUND

Current understanding of the mechanism of action of the pericapsular nerve group (PENG) block is primarily based on cadaver studies. We performed an imaging study in patients undergoing hip surgery to enhance the understanding of the analgesic mechanisms following a PENG block.

MATERIALS AND METHODS

10 patients scheduled for hip surgery received an ultrasound-guided PENG block with 18 mL of 0.5% ropivacaine mixed with 2 mL of a contrast agent. After completion of the block, a high-resolution CT scan was performed to obtain a three-dimensional reconstruction of the injectate's dispersion.

RESULTS

The CT imaging revealed that injectate was mainly confined to the epimysium of the iliacus and the psoas muscle, with a minor spread to the hip capsule. Contrast dye was detected within the iliacus and/or the psoas muscle in all patients. No observed spread to either the subpectineal plane or the obturator foramen was detected.

CONCLUSION

Our study suggests that the analgesic effect of the PENG block may be related to the block of the branches of the femoral nerve traveling within the iliopsoas muscle without a spread pattern commensurate with the block of the obturator nerve.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT06062134).

Use of Two Novel Dyes to Enhance Visualization of Cut Ends of the Vessel in Microvascular Anastomosis-An Experimental Study of 45 Rats

BACKGROUND

Good visualization is a prerequisite for performing microvascular anastomosis. The most commonly used dye, methylene blue, has several limitations: it is washed off quickly and stains all the vessel layers. The objective of our study is to use 2 new novel dyes for improving visualization.

METHODS

After ethical committee approval, 2 Dyes (2% cresyl violet, 1% eosin) were studied in 3 groups, 20 rats in each group and 5 rats in the combined group. End-to-side anastomosis was performed in the classic fashion in 45 rats. After venotomy, the dye was applied to the raw surface of the vessels and subsequently, anastomosis was performed. The improvement in visualization was judged by 3 blinded experts and nonexperts in 4 groups on a scale of 1-10. Scores were statistically analyzed. After 2 weeks, animals were re-explored to check the delayed patency, and segments were harvested for histopathologic analysis.

RESULTS

The immediate and delayed patency rates were 100% (45/45) and 97% (33/34), respectively. In statistical analysis, the combined group (P = 0.005)was judged statistically significant because of the contrast in color. All the layers were stained by both dyes, staining lasted until the end of the surgery. Visibility of the cut ends was better in cresyl violet. All histopathologic findings suggested normal changes at the anastomotic site.

CONCLUSIONS

This study showed that the use of these 2 dyes was not only feasible but highly efficacious. Even though all the layers were stained by both the dyes, the visibility of the cut ends was better. In both dyes, staining lasted until the end of surgery. To the best of our knowledge, this is the first study that has used these 2 novel dyes to improve visualization in microvascular anastomosis in an experimental setting.

Use of topical methylene blue to image nuclear morphometry with a low-cost scanning darkfield microendoscope

Significance

Fiber-optic microendoscopy is a promising approach to noninvasively visualize epithelial nuclear morphometry for early cancer and precancer detection. However, the broader clinical application of this approach is limited by a lack of topical contrast agents available for in vivo use.

Aim

The aim of this study was to evaluate the ability to image nuclear morphometry in vivo with a novel fiber-optic microendoscope used together with topical application of methylene blue (MB), a dye with FDA approval for use in chromoendoscopy in the gastrointestinal tract.

Approach

The low-cost, high-resolution microendoscope implements scanning darkfield imaging without complex optomechanical components by leveraging programmable illumination and the rolling shutter of the image sensor. We validate the integration of our system and MB staining for visualizing epithelial cell nuclei by performing ex vivo imaging on fresh animal specimens and in vivo imaging on healthy volunteers.

Results

The results indicate that scanning darkfield imaging significantly reduces specular reflection and resolves epithelial nuclei with enhanced image contrast and spatial resolution compared to non-scanning widefield imaging. The image quality of darkfield images with MB staining is comparable to that of fluorescence images with proflavine staining.

Conclusions

Our approach enables real-time microscopic evaluation of nuclear patterns and has the potential to be a powerful noninvasive tool for early cancer detection.

Exploring the synergistic effects of amoxicillin and methylene blue on unsaturated lipid structures: A study of Langmuir monolayers and giant unilamellar vesicles

The potentially toxic effects of emerging pollutant mixtures often deviate from the individual compound effects, presenting additive, synergistic, or agonistic interactions. This study delves into the complex world of emerging pollutants' mixtures, with a particular focus on their potential impact on unsaturated lipid DOPC (1,2-dioleoyl-sn-glycerol-3-phosphocholine) structured as both monolayers and bilayers, which are valuable tools for mimicking cell membranes. Specifically, we examine the effects of two common types of pollutants: antibiotics (amoxicillin) and dyes (methylene blue). Utilizing Langmuir monolayers, our research reveals a synergistic effect within the pollutant mixture, as evidenced by pressure-area isotherms and polarization-modulated infrared reflection absorption spectroscopy. We identify the specific chemical interactions contributing to this synergistic effect. Furthermore, through contrast phase microscopy experiments on giant unilamellar vesicles (bilayer system), we find that the individual pollutants and the mixture exhibit similar molecular effects on the bilayer, revealing that the molecular size is a key factor in the bilayer-mixture of pollutant interaction. This highlights the importance of considering molecular size in the interactions with bilayer systems. In summary, our research dissects the critical factors of chemical interactions and molecular size concerning the effects of pollutants on DOPC, serving as simplified models of cell membranes. This study underscores the significance of comprehending the molecular effects of emerging pollutants on human health and the development of models for exploring their intricate interactions with cell membranes.

Ultrafast spectroscopy study of DNA photophysics after proflavine intercalation

Proflavine (PF), an acridine DNA intercalating agent, has been widespread applied as an anti-microbial and topical antiseptic agent due to its ability to suppress DNA replication. On the other hand, various studies show that PF intercalation to DNA can increase photogenotoxicity and has potential chances to induce carcinomas of skin appendages. However, the effects of PF intercalation on the photophysical and photochemical properties of DNA have not been sufficiently explored. In this study, the excited state dynamics of the PF intercalated d(GC)9 • d(GC)9 and d(AT)9 • d(AT)9 DNA duplex are investigated in an aqueous buffer solution. Under 267 nm excitation, we observed ultrafast charge transfer (CT) between PF and d(GC)9 • d(GC)9 duplex, generating a CT state with an order of magnitude longer lifetime compared to that of the intrinsic excited state reported for the d(GC)9 • d(GC)9 duplex. In contrast, no excited state interaction was detected between PF and d(AT)9 • d(AT)9. Nevertheless, a localized triplet state with a lifetime over 5 µs was identified in the PF-d(AT)9 • d(AT)9 duplex.

Interaction of Methylene Blue with Severe Acute Respiratory Syndrome Coronavirus 2 Envelope Revealed by Molecular Modeling

Methylene blue has multiple antiviral properties against Severe Acute Respiratory Syndrome-related Coronavirus 2 (SARS-CoV-2). The ability of methylene blue to inhibit different stages of the virus life cycle, both in light-independent and photodynamic processes, is used in clinical practice. At the same time, the molecular aspects of the interactions of methylene blue with molecular components of coronaviruses are not fully understood. Here, we use Brownian dynamics to identify methylene blue binding sites on the SARS-CoV-2 envelope. The local lipid and protein composition of the coronavirus envelope plays a crucial role in the binding of this cationic dye. Viral structures targeted by methylene blue include the S and E proteins and negatively charged lipids. We compare the obtained results with known experimental data on the antiviral effects of methylene blue to elucidate the molecular basis of its activity against coronaviruses.

Microendoscopy in vivo for the pathological diagnosis of cervical precancerous lesions and early cervical cancer

BACKGROUND

Cervical cancer is an important public health problem. Conventional colposcopy is inefficient in the diagnosis of cervical lesions and massive biopsies result in trauma. There is an urgent need for a new clinical strategy to triage women with abnormal cervical screening results immediately and effectively. In this study, the high-resolution microendoscopy combined with methylene blue cell staining technology was used to perform real-time in vivo imaging of the cervix for the first time.

METHODS

A total of 41 patients were enrolled in the study. All patients underwent routine colposcopy and cervical biopsy, and high-resolution images of methylene blue-stained cervical lesions were obtained in vivo using microendoscopy. The cell morphological features of benign and neoplastic cervical lesions stained with methylene blue under microendoscopy were analyzed and summarized. The microendoscopy and histopathology findings of the high-grade squamous intraepithelial lesion (HSIL) and more severe lesions were compared.

RESULTS

The overall consistency of microendoscopy diagnosis with pathological diagnosis was 95.12% (39/41). Diagnostic cell morphological features of cervicitis, low-grade squamous intraepithelial lesion (LSIL), HSIL, adenocarcinoma in situ, and invasive cancer were clearly demonstrated in methylene blue stained microendoscopic images. In HSIL and more severe lesions, microendoscopic methylene blue cell staining technology can show the microscopic diagnostic features consistent with histopathology.

CONCLUSIONS

This study was an initial exercise in the application of the microendoscopy imaging system combined with methylene blue cell staining technology to cervical precancerous lesions and cervical cancer screening. The results provided the basis for a novel clinical strategy for triage of women with abnormal cervical screening results using in vivo non-invasive optical diagnosis technology.

In vitro and in vivo phototoxicity on gastric mucosa induced by methylene blue

BACKGROUND

Methylene blue (MB) is used endoscopically to demarcate tumors and as a photosensitizer in photodynamic therapy (PDT). However, there are few in vivo studies about its toxicity in healthy stomach tissue. We performed sequential in vitro and in vivo analyses of MB-induced phototoxicity.

METHODS

We performed in vitro experiments using the AGS human gastric cancer cell line treated with light-emitting diode (LED) irradiation (3.6 J/cm²) and MB. Cytotoxicity was evaluated using terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. In vivo toxicity was evaluated in the stomach of beagles using the same dose of fiber-optic LED via gastroscopy, after spraying 0.1% and 0.5% MB solutions. Stomach tissue was also evaluated using the TUNEL assay.

RESULTS

In vitro, increased concentrations of MB led to higher TUNEL scores. However, cell viability was significantly lower after MB plus LED irradiation than after treatment with MB alone (P < 0.001). In vivo, the TUNEL score was highest immediately after treatment with 0.1% or 0.5% MB plus light irradiation, and the score was significantly higher in the LED illumination plus MB group than in the control group (P < 0.05). The elevated TUNEL score was maintained for 3 days in the MB plus light irradiation group but returned to normal levels on day 10.

CONCLUSIONS

: Endoscopic light application with MB 0.5% concentration to the stomach may be regarded as a safe procedure despite some DNA injuries in the early period.

Improved Bladder Tumor RNA Isolation from Archived Tissues Using Methylene Blue for Normalization, Multiplex RNA Hybridization, Sequencing and Subtyping

Methylene blue (MB) is a dye used for histology with clinical importance and intercalates into nucleic acids. After MB staining of formalin fixed paraffin embedded (FFPE) muscle invasive bladder cancer (MIBC) and normal urothelium, specific regions could be microdissected. It is not known if MB influences RNA used for gene expression studies. Therefore, we analyzed MIBC using five different RNA isolation methods comparing patient matched FFPE and fresh frozen (FF) tissues pre-stained with or without MB. We demonstrate a positive impact of MB on RNA integrity with FF tissues using real time PCR with no interference of its chemical properties. FFPE tissues showed no improvement of RNA integrity, which we propose is due to formalin induced nucleotide crosslinks. Using direct multiplex RNA hybridization the best genes for normalization of MIBC and control tissues were identified from 34 reference genes. In addition, 5SrRNA and 5.8SrRNA were distinctive reference genes detecting <200 bp fragments important for mRNA analyses. Using these normalized RNAs from MB stained MIBC and applying multiplex RNA hybridization and mRNA sequencing, a minimal gene expression panel precisely identified luminal and basal MIBC tumor subtypes, important for diagnosis, prognosis and chemotherapy response.

Phototherapeutic Induction of Immunogenic Cell Death and CD8+ T Cell-Granzyme B Mediated Cytolysis in Human Lung Cancer Cells and Organoids

Augmenting T cell mediated tumor killing via immunogenic cancer cell death (ICD) is the cornerstone of emerging immunotherapeutic approaches. We investigated the potential of methylene blue photodynamic therapy (MB-PDT) to induce ICD in human lung cancer. Non-Small Cell Lung Cancer (NSCLC) cell lines and primary human lung cancer organoids were evaluated in co-culture killing assays with MB-PDT and light emitting diodes (LEDs). ICD was characterised using immunoblotting, immunofluorescence, flow cytometry and confocal microscopy. Phototherapy with MB treatment and low energy LEDs decreased the proliferation of NSCLC cell lines inducing early necrosis associated with reduced expression of the anti-apoptotic protein, Bcl2 and increased expression of ICD markers, calreticulin (CRT), intercellular cell-adhesion molecule-1 (ICAM-1) and major histocompatibility complex I (MHC-I) in NSCLC cells. MB-PDT also potentiated CD8+ T cell-mediated cytolysis of lung cancer via granzyme B in lung cancer cells and primary human lung cancer organoids.

Synthesis of Metalorganic Copolymers Containing Various Contorted Units and Iron(II) Clathrochelates with Lateral Butyl Chains: Conspicuous Adsorbents of Lithium Ions and Methylene Blue

We report the synthesis of three highly soluble metalorganic copolymers, TCP1-3, that were made from a one-pot complexation of iron(II) clathrochelate units that are interconnected by various thioether-containing contorted groups. TCP1-3 were converted into their poly(vinyl sulfone) derivatives OTCP1-3 quantitatively via the selective oxidation of the thioether moieties into their respective sulfones. All of the copolymers, TCP1-3 and OTCP1-3, underwent structural analysis by various techniques; namely, ¹H- and ¹³C-nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and gel permeation chromatography (GPC). The copolymers were tested as potent lithium ions adsorbents revealing a maximum adsorption (q_m) value of 2.31 mg g^-1 for OTCP2. Furthermore, this same copolymer was found to be a promising adsorbent of methylene blue (MEB); an isothermal adsorption study divulged that OTCP2's uptake of MEB from an aqueous solution (following the Langmuir model) was, at maximum adsorption capacity, (q_m) of 480.77 mg g^-1; whereas the kinetic study divulged that the adsorption follows pseudo second-order kinetics with an equilibrium adsorption capacity (q_e,cal) of 45.40 mg g^-1.

Methylene blue applied to N95 respirators and medical masks for SARS-CoV-2 decontamination: What is the likelihood of inhaling methylene blue?

Background

Global shortage of personal protective equipment (PPE), as consequence of the COVID-19 global pandemic, has unmasked significant resource inequities prompting efforts to develop methods for safe PPE decontamination for reuse. The World Health Organization (WHO) in their Rational Use of PPE bulletin cited the use of a photodynamic dye, methylene blue, and light exposure as a viable option for N95 respirator decontamination. Because WHO noted that methylene blue (MB) would be applied to surfaces through which health care workers breathe, we hypothesized that little to no MB will be detectable by spectroscopy when the PPE is subjected to MB at supraphysiologic airflow rates.

Methods

A panel of N95 respirators, medical masks, and cloth masks were sprayed with 5 cycles of 1,000 uM MB solution. Mask coupons were subjected to the equivalent of 120 L/min of 100% humidified air flow. Effluent gas was trapped in an aqueous solution and the resultant fluid was sampled for MB absorbance with a level of detection of 0.004 mg/m3.

Results

No detectable MB was identified for any mask using Ultraviolet-Visible spectroscopy.

Conclusions

At 500-fold the amount of MB applied to N95 respirators and medical masks as were used for the decontamination study cited in the WHO Rational Use of PPE bulletin, no detectable MB was observed, thus providing safety evidence for the use of methylene blue and light exposure for mask decontamination.

Sentinel Lymph Node Mapping: Current Applications and Future Perspectives in Gynecology Malignant Tumors

The sentinel lymph nodes (SLNs) is a group of lymph nodes initially involved in the metastatic spread of cancer cells. SLN mapping refers to intraoperative localization and biopsy of SLNs with specific tracers to assess lymph node metastases. It is widely used in a variety of tumor surgeries for its high sensitivity and high negative predictive value. In the evaluation of the status of lymph node metastases in gynecological malignancies, it has received increasingly more attention due to its minor invasiveness, few complications, and high diagnosis rate. The National Comprehensive Cancer Network (NCCN) guidelines provide an excellent introduction to the indications and methods of SLN techniques in vulvar, cervical, and endometrial cancers, but they provide little explanation about some specific issues. In this review, we summarize different dyes and injection methods and discuss the indications of application and the clinical trials of SLN mapping in gynecological malignant tumors, aiming to provide a reference for the rational application of sentinel techniques in gynecology malignant tumors before relevant guidelines are updated.

Review on Methylene Blue: Its Properties, Uses, Toxicity and Photodegradation

The unavailability of clean drinking water is one of the significant health issues in modern times. Industrial dyes are one of the dominant chemicals that make water unfit for drinking. Among these dyes, methylene blue (MB) is toxic, carcinogenic, and non-biodegradable and can cause a severe threat to human health and environmental safety. It is usually released in natural water sources, which becomes a health threat to human beings and living organisms. Hence, there is a need to develop an environmentally friendly, efficient technology for removing MB from wastewater. Photodegradation is an advanced oxidation process widely used for MB removal. It has the advantages of complete mineralization of dye into simple and nontoxic species with the potential to decrease the processing cost. This review provides a tutorial basis for the readers working in the dye degradation research area. We not only covered the basic principles of the process but also provided a wide range of previously published work on advanced photocatalytic systems (single-component and multi-component photocatalysts). Our study has focused on critical parameters that can affect the photodegradation rate of MB, such as photocatalyst type and loading, irradiation reaction time, pH of reaction media, initial concentration of dye, radical scavengers and oxidising agents. The photodegradation mechanism, reaction pathways, intermediate products, and final products of MB are also summarized. An overview of the future perspectives to utilize MB at an industrial scale is also provided. This paper identifies strategies for the development of effective MB photodegradation systems.

Photo-activated proflavine degrades protein and impairs enzyme activity: Involvement of hydroxyl radicals

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Generation of hydroxyl radical (·OH) increased by proflavine upon illumination with fluorescent light.

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Proflavine resulted in oxidative modifications and degradation of protein and enzyme structure.

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The addition of Cu (II) augmented photo-illuminated proflavine to generate hydroxyl radicals.

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Proflavine-induced hydroxyl radicals have a deleterious influence on protein and enzyme activity.

Proflavine is a well-known antiseptic and bacteriostatic drug, however, it has the potential to be hazardous and mutagenic. Proflavine enters cells and intercalates between DNA base pairs, resulting in mutation and replication inhibition. Previously several investigators demonstrated that photo-activated proflavine generated double-stranded DNA breakage and protein structural alterations. The present study investigated the role of hydroxyl radical (·OH) due to activation of proflavine in the breakdown of protein and enzyme by photo-activated proflavine. The results show that the formation of hydroxyl radicals increased as the photo-illumination period increased, as did the concentrations of proflavine and Cu (II). As demonstrated by SDS-PAGE, the excess of free radicals due to proflavine resulted in oxidative modifications and degradation of BSA protein and trypsin enzyme. Additionally, with an increase in Cu (II) concentration, photo-illuminated proflavine induced a considerable loss of enzyme activity and also accelerated the degradation of the enzyme. Bathocuproine, a particular Cu (I)-sequestering agent, prevented protein degradation and enzyme inactivation. Hydroxyl radical scavengers inhibited the protein-damaging process, indicating that hydroxyl radicals play a substantial role in protein damage. The tryptophan moiety was quenched by proflavine, demonstrating that it binds to proteins and enzymes, changing their structure and activity. As a result, this study helps to better understand proflavine's deleterious influence on protein and enzyme degradation by oxygen-free radicals.

Thoracoscopic detection of thoracic ducts after ultrasound-guided intrahepatic injection of indocyanine green detected by near-infrared fluorescence and methylene blue in dogs

OBJECTIVE

To describe and compare onset and intensity of thoracic duct (TD) coloration in healthy dogs after intrahepatic injection of either indocyanine green (ICG) visualized by intraoperative near-infrared fluorescence lymphography (NIRFL) or direct thoracoscopic visualization of methylene blue dye (MB).

STUDY DESIGN

Prospective study.

ANIMALS

Healthy adult Beagle dogs (n = 5).

METHODS

All dogs had biochemical panels and complete blood counts preoperatively. Computed tomography lymphography (CTL) was performed prior to a standard 3-port thoracoscopic approach. A mixture of MB and ICG was injected by ultrasound-guided percutaneous injection into right or left-sided hepatic lobes. Data collected included dose of contrast agent (MB vs. ICG), injection site, timing, and quality of operative TD identification. Potential hepatic injury was assessed by repeat laboratory evaluation and abdominal ultrasound 14 days postoperatively.

RESULTS

Preoperative CTL provided a diagnostic study in 5/5 dogs. After intrahepatic injection of combined dyes, NIRFL allowed visualization of TDs in 5/5 dogs, but MB did not result in visible TD coloration in any dog. Intrahepatic injection of ICG achieved successful NIRFL in a median time of 6 minutes and persisted for the 20 minute observation period in all five dogs. All dogs recovered without complication and were subsequently adopted.

CONCLUSION

NIRFL of the TD can be achieved with intraoperative hepatic injection of ICG. Intrahepatic injection of MB did not result in visible TD coloration.

CLINICAL SIGNIFICANCE

Hepatic intra-parenchymal injection is a reliable alternative portal into the TD system for intraoperative visualization of TD anatomy using ICG in dogs.

Methylene Blue has a potent antiviral activity against SARS-CoV-2 and H1N1 influenza virus in the absence of UV-activation in vitro

Methylene blue is an FDA (Food and Drug Administration) and EMA (European Medicines Agency) approved drug with an excellent safety profile. It displays broad-spectrum virucidal activity in the presence of UV light and has been shown to be effective in inactivating various viruses in blood products prior to transfusions. In addition, its use has been validated for methemoglobinemia and malaria treatment. In this study, we first evaluated the virucidal activity of methylene blue against influenza virus H1N1 upon different incubation times and in the presence or absence of light activation, and then against SARS-CoV-2. We further assessed the therapeutic activity of methylene blue by administering it to cells previously infected with SARS-CoV-2. Finally, we examined the effect of co-administration of the drug together with immune serum. Our findings reveal that methylene blue displays virucidal preventive or therapeutic activity against influenza virus H1N1 and SARS-CoV-2 at low micromolar concentrations and in the absence of UV-activation. We also confirm that MB antiviral activity is based on several mechanisms of action as the extent of genomic RNA degradation is higher in presence of light and after long exposure. Our work supports the interest of testing methylene blue in clinical studies to confirm a preventive and/or therapeutic efficacy against both influenza virus H1N1 and SARS-CoV-2 infections.

Human Glioblastoma Visualization: Triple Receptor-Targeting Fluorescent Complex of Dye, SIWV Tetra-Peptide, and Serum Albumin Protein

Fluorescence guided surgery (FGS) has been highlighted in the clinical site for guiding surgical procedures and providing the surgeon with a real-time visualization of the operating field. FGS is a powerful technique for precise surgery, particularly tumor resection; however, clinically approved fluorescent dyes have often shown several limitations during FGS, such as non-tumor-targeting, low in vivo stability, insufficient emission intensity, and low blood-brain barrier penetration. In this study, we disclose a fluorescent dye complex, peptide, and protein for the targeted visualization of human glioblastoma (GBM) cells and tissues. Our noble triple receptor-targeting fluorescent complex (named BSA-OXN-SIWV) consists of (i) dipolar oxazepine dye (OXN), which has high stability, low cytotoxicity, bright fluorescence, and two-photon excitable, (ii) tetra-peptide (SIWV) for the targeting of the caveolin-1 receptor, and (iii) bovine serum-albumin (BSA) protein for the targeting of albondin (gp60) and secreted protein acidic and rich in cysteine receptor. The photophysical properties and binding mode of BSA-OXN-SIWV were analyzed, and the imaging of GBM cell lines and human clinical GBM tissues were successfully demonstrated in this study. Our findings hold great promise for the application of BSA-OXN-SIWV to GBM identification and the surgery at clinical sites, as a new FGS agent.

Methylene Blue and Proflavine as Intraarterial Marker for Functional Perforazome-Comparative Study

Methylene blue (MB) is both a dye and a medicine known and used for a long time including as lymphatic tracer in melanoma and breast cancer for revealing sentinel lymph nodes. Proflavine (PRO) is an acriflavine dye, used as bacteriostatic disinfectant against many gram-positive bacteria that was also successfully applied to evaluate morphopathological changes in tissues. This study was performed on a group of twenty-eight Wistar rats and had as its main objective the in vivo evaluation of the use of MB and PRO as perforator tracers. The two dyes proved to be effective functional perforasome tracers with medium inflammatory infiltrate in the skin of the island perforator flap which heals perfectly at 14 days with complete absence of the inflammatory reaction. At the same injected amount, PRO seems to determine a greater inflammatory reaction compared with MB, but in smaller concentration, the inflammatory response is absent in the case of PRO. In conclusion, both substances tested within this in vivo study are good functional perforasome tracers, but PRO has the advantage of the absence of inflammatory reaction when using lower concentrations, while preserving unalerted its efficiency as tracer.

Methylene Blue-Current Knowledge, Fluorescent Properties, and Its Future Use

Methylene blue is a fluorescent dye discovered in 1876 and has since been used in different scientific fields. Only recently has methylene blue been used for intraoperative fluorescent imaging. Here, the authors review the emerging role of methylene blue, not only as a dye used in clinical practice, but also as a fluorophore in a surgical setting. We discuss the promising potential of methylene blue together with the challenges and limitations among specific surgical techniques. A literature review of PubMed and Medline was conducted based on the historical, current and future usage of methylene blue within the field of medicine. We reviewed not only the current usage of methylene blue, but we also tried to grasp its’ function as a fluorophore in five main domains. These domains include the near-infrared imaging visualization of ureters, parathyroid gland identification, pancreatic tumors imaging, detection of breast cancer tumor margins, as well as breast cancer sentinel node biopsy. Methylene blue is used in countless clinical procedures with a relatively low risk for patients. Usage of its fluorescent properties is still at an early stage and more pre-clinical, as well as clinical research, must be performed to fully understand its potentials and limitations.

Methylene blue induces the soxRS regulon of Escherichia coli

Extensive application of methylene blue (MB) for therapeutic and diagnostic purposes, and reports for unwanted side effects, demand better understanding of the mechanisms of biological action of this thiazine dye. Because MB is redox-active, its biological activities have been attributed to transfer of electrons, generation of reactive oxygen species, and antioxidant action. Results of this study show that MB is more toxic to a superoxide dismutase-deficient Escherichia coli mutant than to its SOD-proficient parent, which indicates that superoxide anion radical is involved. Incubation of E. coli with MB induced the enzymes fumarase C, SOD, nitroreductase A, and glucose-6-phosphate dehydrogenase, all controlled by the soxRS regulon. Induction of these enzymes was prevented by blocking protein synthesis with chloramphenicol and was not observed when soxRS-negative mutants were incubated with MB. These results show that MB is capable of inducing the soxRS regulon of E. coli, which plays a key role in protecting bacteria against oxidative stress and redox-cycling compounds. Irrespective of the abundance of heme-containing proteins in living cells, which are preferred acceptors of electrons from the reduced form of MB, reduction of oxygen to superoxide radical still takes place. Induction of the soxRS regulon suggests that in humans, beneficial effects of MB could be attributed to activation of redox-sensitive transcription factors like Nrf2 and FoxO. If defense systems are compromised or genes coding for protective proteins are not induced, MB would have deleterious effects.

A protein interaction map identifies existing drugs targeting SARS-CoV-2

BACKGROUND

Severe acute respiratory syndrome coronavirus (SARS-CoV-2), an emerging Betacoronavirus, is the causative agent of COVID-19. Angiotensin converting enzyme 2 (ACE2), being the main cell receptor of SARS-CoV-2, plays a role in the entry of the virus into the cell. Currently, there are neither specific antiviral drugs for the treatment or preventive drugs such as vaccines.

METHODS

We proposed a bioinformatics analysis to test in silico existing drugs as a fast way to identify an efficient therapy. We performed a differential expression analysis in order to identify differentially expressed genes in COVID-19 patients correlated with ACE-2 and we explored their direct relations with a network approach integrating also drug-gene interactions. The drugs with a central role in the network were also investigated with a molecular docking analysis.

RESULTS

We found 825 differentially expressed genes correlated with ACE2. The protein-protein interactions among differentially expressed genes identified a network of 474 genes and 1130 interactions.

CONCLUSIONS

The integration of drug-gene interactions in the network and molecular docking analysis allows us to obtain several drugs with antiviral activity that, alone or in combination with other treatment options, could be considered as therapeutic approaches against COVID-19.