Maintaining moderate levels of hypochlorous acid promotes neural stem cell proliferation and differentiation in the recovery phase of stroke

It has been shown clinically that continuous removal of ischemia/reperfusion-induced reactive oxygen species is not conducive to the recovery of late stroke.Indeed,previous studies have shown that excessive increases in hypochlorous acid after stroke can cause severe damage to brain tissue.Our previous studies have found that a small amount of hypochlorous acid still exists in the later stage of stroke,but its specific role and mechanism are currently unclear.To simulate stroke in vivo,a middle cerebral artery occlusion rat model was established,with an oxygen-glucose deprivation/reoxygenation model established in vitro to mimic stroke.We found that in the early stage(within 24 hours)of ischemic stroke,neutrophils produced a large amount of hypochlorous acid,while in the recovery phase(10 days after stroke),microglia were activated and produced a small amount of hypochlorous acid.Further,in acute stroke in rats,hypochlorous acid production was prevented using a hypochlorous acid scavenger,taurine,or myeloperoxidase inhibitor,4-aminobenzoic acid hydrazide.Our results showed that high levels of hypochlorous acid(200μM)induced neuronal apoptosis after oxygen/glucose deprivation/reoxygenation.However,in the recovery phase of the middle cerebral artery occlusion model,a moderate level of hypochlorous acid promoted the proliferation and differentiation of neural stem cells into neurons and astrocytes.This suggests that hypochlorous acid plays different roles at different phases of cerebral ischemia/reperfusion injury.Lower levels of hypochlorous acid(5 and 100μM)promoted nuclear translocation ofβ-catenin.By transfection of single-site mutation plasmids,we found that hypochlorous acid induced chlorination of theβ-catenin tyrosine 30 residue,which promoted nuclear translocation.Altogether,our study indicates that maintaining low levels of hypochlorous acid plays a key role in the recovery of neurological function.

Hypochlorous Acid for Septic Abdominal Processes Using a Unique Negative Pressure Wound Therapy System:A Pilot Study

Background: Septic open abdomens occur in trauma, burn and surgery. Currently, multiple concentrations of hypochlorous acid solutions have effectively decreased the microbiotic burden in wounds. We hypothesized that Vashe?, a neutral hypochlorous acid solution (V-HOCL), would be safe as an intraperitoneal irrigation or washout disinfectant for septic open abdomens utilizing negative pressure wound therapy. Methods: This is a retrospective observational review of patients who required delayed abdominal closures after exploratory laparotomies. Group A (n = 8) had cyclical V-HOCL irrigation to their open abdomens combining AbtheraTM and V.A.C. Dressing System for negative pressure wound therapy with irrigation (NPWT-i) and Group B (n = 9) had intra-abdominal V-HOCL washouts. Results: Fifty percent of both groups had either septic or hemorrhagic shock on admission. Compared to Group B, Group A patients were older (median 50 vs 37 years), and had a median hospitalization of 28 vs 8 days, 4 times as many operations, more acute renal failure and co-morbidities. No statistically significant differences were detected be-tween the two treatment methods with the V-HOCL delivery and removal. Conclusion: There were no episodes of electrolyte imbalance, hypotension, hypertension, anaphylaxis, hemorrhage, visceral injury or systemic toxicity. V-HOCL with/without NPWT-i irrigation was a safe modality and tolerated well in this study.

Responsive mechanism of three novel hypochlorous acid fluorescent probes and solvent effect on their sensing performance

Optical properties and responsive mechanisms of three newly synthesized fluorescent probes for hypochlorous acid （HOC1） are investigated by employing time-dependent density functional theory. The computational results show that the absorption and emission properties of these probes change obviously when they react with hypochlorous acid. It is found that the probe FHZ has the best performance according to the probing behavior. Moreover, the responsive mechanisms of the probes are studied by analyzing the distributions of molecular orbitals and charge transfer, which are shown as the photon- induced electron transfer （PET） for FHZ and the intramolecular charge transfer OCT） for the other two probes. Specially, solvent effect on optical properties of the probe FHZ before and after reaction is studied within the polarizable continuum model （PCM）. It is shown that performance of the probe depends crucially on the solvent polarity. Our computational results agree well with the experimental measurement, and provide information for design of efficient two-photon fluorescent probes.

Hypochlorous Acid Induces Caspase Dependent Apoptosis in <i>Saccharomyces cerevisiae</i>

Hypochlorous acid (HOCl) is a strong oxidant produced by activated neutrophils via the myeloperoxidase (MPO) enzyme in order to fight against infections. Because of their antimicrobial and antiviral properties, stabilized HOCl solutions were produced to be used as a disinfectant and became a recommended disinfectant against COVID-19 by the US Environmental Protection Agency. Aberrant MPO enzyme activity results in abundant HOCl production which is related to the development and/or progression of several diseases including atherosclerosis, cardiovascular and neurodegenerative diseases. Previous studies investigating the effect of HOCl on the mode of cell death in different cell types reported that HOCl induces both apoptosis and necrosis depending on its concentration. However, the data on the apoptotic pathway triggered by HOCl is controversial. In this study, we investigated the mode of cell death induced by different concentrations of HOCl in Saccharomyces cerevisiae. Our data revealed that HOCl leads to cell death within 1 minute at 170 μM and above. At 340 μM, HOCl causes a rapid necrosis, while 170 μM HOCl leads to apoptosis. HOCl-induced apoptosis is mostly caspase dependent and Aif1 doesn’t have a significant role.

A general strategy for selective detection of hypochlorous acid based on triazolopyridine formation

Triazolopyridines are an important kind of fused-ring compounds.A HOCl-promoted triazolopyridine formation strategy is reported here for the first time in which hypochlorous acid(HOCl)mildly and efficiently promotes the formation of 1,2,4-triazolo[4,3-a]pyridines NT1-NT6 from various 2-pyridylhydrazones N1-N6.N6,a rhodol-pyridylhydrazone hybrid,was developed into a fluorescent probe for the selective detection of HOCl,and successfully applied to probe endogenous HOCl in living cells and zebrafish in situ and in real time.The present intramolecular cyclization reaction is selective and atom-economical,thereby not only providing an important approach for the convenient synthesis of triazolopyridines,but also offering a general strategy for sensitive,selective and biocompatible detection of endogenous HOCl in complex biosystems.

Recurring Real-Time Monitoring of Inflammations in Living Mice with a Chemiluminescent Probe for Hypochlorous Acid

Probes for in vivo imaging of hypochlorous acid(HOCl),one of the most important reactive oxygen species in innate immunity,are urgently needed to understand the pathogenesis of autoimmune and neuroinflammatory disorders.As a strong oxidant,HOCl could bleach near-infrared sensors and inactivate luciferase readily,making in vivo imaging overwhelmingly challenging.Via fine-tuning of a selective HOCl sensing moiety,HOCl stable spacer,and bright chemiluminescent scaffold,we have developed HOCl-CL-510 as a highly selective and sensitive probe for HOCl detection both in vitro and in vivo.In particular,we achieved recurring real-time monitoring of HOCl in both acute and chronic inflammation models in living mice,providing a new chemical tool for dynamic monitoring of disease development with reduced usage of experimental animals.

Utilizing Instilling Negative Pressure Wound Therapy with Vashe Wound Solution for an Infected Sternal Dehiscence: A Case Report

Utilization of negative pressure wound therapy with instillation (NPWTi) for sternal dehiscence wounds secondary to sternal wound infection after surgery has become an accepted therapy. NPWTi accelerates wound healing through macrostrain, microstrain, and cyclic fluid instillation. Wounds benefit from additional superficial infection control with the removal of microorganisms, the release of proinflammatory mediators, stimulation of angiogenesis, as well as mechanical debridement. However, very few cases of utilizing NPWTi in the treatment of sternal wound infections have been reported in the literature. This case study describes the use of NPWTi with hypochlorous acid for the treatment of a sternal wound infection.

A highly sensitive fluorescent HClO probe for discrimination between cancerous and normal cells/tissues

Elevated level of hypochlorous acid(HClO)is closely associated with cancer development.Identifying HClO level in cancer cells would provide important evidence in either early-stage cancer diagnostics or monitoring of its treatment efficiency.In this work,a new pyronine-based fluorescent probe for rapid and sensitive detection of HClO was developed by condensing meso-formyl pyronine(PyCHO)with 2-hydrazinopyridine to form meso-pyridylhydrazone-functionalized pyronine PyHP,PyHP is nonfluorescent due to the excited-state C=N isomerization nonradiative decay,whereas the HClO-triggered formation of meso-triazolopyridyl pyronine PyTP abolishes the C=N isomerization and thus greatly enhances the fluorescence.With the probe,the cancer cells/tumor were distinguished with high-contrast from normal ones by laser confocal fluorescence imaging,and the tumor-to-normal(T/N)ratios obtained exceed the clinically acceptable threshold of 2.0.Moreover,its capability of in vivo imaging tumor was also demonstrated.These results indicate the potential of PyHP as an effective tool in the early clinical diagnosis of cancers.

A fluorescent probe operating under weak acidic conditions for the visualization of HOCl in solid tumors in vivo

Levels of reactive oxygen species(ROS)in cancer cells or in the tumor microenvironment differ noticeably from those in normal cells and cellular microenvironments because ROS play important roles in all aspects of tumor physiology.However,due to the lack of adequate tools,it is difficult to study the relationship between ROS,especially certain types of ROS(e.g.,HOCl),and cancer.We report herein an HOCl-specific fluorescent probe,FDOCl-20,containing a thiocarbamide group as a receptor,for the visualization of HOCl in solid tumors in vivo.This probe displays high selectivity and sensitivity to HOCl,and is appropriate for use in acidic conditions,including the tumor microenvironment.Using FDOCl-20 as a tool,we can visualize HOCl in solid tumors in vivo.Importantly,the fluorescent intensity of FDOCl-20 is proportional to tumor volume.Thus,FDOCl-20 is a useful tool to investigate the relationship between HOCl and the physiological processes of tumors.

Molecular engineering of ultra-sensitive fluorescent probe with large Stokes shift for imaging of basal HOCl in tumor cells and tissues

Fluorescent probes have been widely employed in biological imaging and sensing.However,it is always a challenge to design probes with high sensitivity.In this work,based on rhodamine skeleton,we developed a general strategy to construct sensitivity-enhanced fluorescent probe with the help of theoretical calculation for the first time.As a proof of concept,we synthesized a series of HOCl probes.Experiment results showed that with the C-9 of pyronin moiety of rhodamine stabilized by an electron donor group,probe DQF-S exhibited an importantly enhanced sensitivity(LOD:0.2 nmol/L)towards HOCl together with fast response time(<10 s).Moreover,due to the breaking symmetrical electron distribution by another electron donor group,the novel rhodamine probe DQF-S displayed a far red to near-infrared emission(>650 nm)and large Stokes shift.Bioimaging studies indicated that DQF-S can not only effectively detect basal HOCl in various types of cells,but also be successfully applied to image tumor tissue in vivo.These results demonstrate the potential of our design as a useful strategy to develop excellent fluorescent probes for bioimaging.

Recent development in fluorescent probes based on attacking of double bond and masking of functional group

The works on the procedure of fluorescent sensors for the detection of biological analytes are extremely momentous.Among diverse analytical approaches,fluorescence is the most eye-catching due to its high sensitivity,selectivity,rapidity,robustness,ease of measurement and non-destructive approaches.Herein,we show different fluorescent probes synthesized for estimation and detection of biological analytes(H_(2)S,SO_(3)^(2-)/HSO_(3)^(-),H_(2)O_(2),HOCl,HNO,ONOO^(-)).These probes were constructed by masking the functional groups (hydroxyl and amino) of fluorophore and formation of active C=C,C=N,C=O and N=N for specific analytes.In this review we concentrate on synthesis of the probe,their photophysical properties and applications to biological studies.

A mitochondria-targeted fluorescent probe for ratiometric detection of hypochlorite in living cells

Hypochlorous acid（HOCl） plays a vital role in many physiological and pathological processes as one of reactive oxygen species（ROS）. Developing highly sensitive and selective methods for HOCl detection is of significant interest. In this work, we developed a benzothiazole based probe 1 for ratiometric fluorescence detection of hypochlorite in living cells. The probe can detect HOCl with high selectivity, fast response（within 30 s） as well as low detection limit（0.18 mmol/L）. Fluorescence co-localization studies demonstrated that probe 1 was a mitochondria-targeted fluorescent probe. Furthermore, confocal fluorescence images of He La cell indicated that probe 1 could be used for monitoring intracellular HOCl in living cells. Finally, test strips experiment suggests that the probe 1 can detect the hypochlorous acid in tap water accompanied by remarkable color change.

A Long-wavelength Emissive Phenothiazine Derived Fluorescent Probe for Detecting HOCI Upregulation in 5-FU Stimulated Living Cells

The endogenous hypochlorous acid(HOCI) has been evidenced in a variety of cellular courses. However, the role of HOCI in most pathophysiological processes still keeps unclear because of the limited detecting tools. In this work, we presented the pre- paration of a phenothiazine-derived fluorescent probe CIO-1 for HOCI detection with a cyanopyridinium moiety to improve its water solubility and lengthen its emission wavelength. The HOCI-promoted oxidation of sulfur atom in the probe resulted in a 460-fold emission intensity enhancement at 635 nm with high selectivity and sensitivity(detection limit: 1.12 nmol/L). The rapid response(5 s) also endowed the probe with real-time detection ability. Successfully, CIO-1 was devoted to the bioimaging of endogenous HOCI in inflamed RAW 264.7 cells and 5-fluorouracil-treated MCF-7 cells.