Organic Sensitizers Research Articles

P66Shc signaling does not contribute to tubular damage induced by renal ischemia-reperfusion injury in rat

Renal ischemia-reperfusion (IR) injury is one of the major causes of acute kidney injury and represents a significant risk factor for renal transplantation. The level of renal damage is influenced by the ischemic duration and is caused by excessive amounts of produced reactive oxygen species (ROS). Adaptor protein p66Shc is known to regulate cellular and organ's sensitivity to oxidative stress and to contribute significantly to mitochondrial production of hydrogen peroxide in stress conditions. Studies carried out in cultured renal cells suggest that p66Shc-mediated mitochondrial dysfunction and ROS production are responsible for renal ischemic injury. We used our genetically modified rats, which either lack p66Shc expression, or express p66Shc variant, which constitutively generates increased quantities of hydrogen peroxide, to evaluate potential contribution of p66Shc signaling to renal damage in ischemia reperfusion rat model. Analysis of outer medulla tubule damage revealed the lack of contribution of either p66Shc expression or its constitutive signaling to IR injury in rat model.

Evaluation of Pediatric Imaging Modalities Practices of Radiologists and Technologists: A Survey-Based Study.

IntroductionRadiation protection for pediatric patients is the main concern in pediatric computed tomography (CT) due to their sensitive organs, such as the brain and the thyroid glands. Accordingly, an optimization of pediatric CT practices is vital to minimize the radiation dose for this population.AimTo assess the pediatric CT practices of radiologists and technologists in a CT unit.Materials and MethodsThe study was conducted among 26 hospitals, located in various regions in Saudi Arabia. A total of 200 hard copies of the questionnaire were distributed manually and were collected for analysis. In total, 117 completed surveys were gathered from technologies, while 49 were gathered from radiologists.ResultsIn the case of infants with hydrocephalus, 65% of the radiologists ordered an ultrasound (US), 24% ordered a head CT scan, and 10% ordered a magnetic resonance imaging (MRI) and general X-ray for diagnosis. For pediatric patients complaining of persistent headache, 59% and 27% of the radiologists recommended CT and MRI, respectively, for diagnosis.ConclusionMost of the radiologists utilize CT head scan to diagnose persistent headache (by 59%) and ventriculoperitoneal shunt (VPS) malfunction (by 41%) in pediatric patients compared with the other modalities. The use of CT can increase the risk of later malignancy among pediatric patients due to radiation exposure. Alternative imaging modalities such as US and MRI (non-ionized radiation) should be considered to reduce the ionizing radiation hazards and optimize the current practices of radiologists. Most of the technologists follow radiation protection protocols in this study as 63% of the technologists used lead apron for pediatric patient’s protection. Radiation awareness training for the technologists could improve the knowledge about the benefits of using lead apron and reduce the radiation risks in pediatric patients.

The activation of SIRT3 by dexmedetomidine mitigates limb ischemia-reperfusion-induced lung injury.

BackgroundThe lung is one of the most sensitive organs, and is vulnerable to injury caused by limb ischemia-reperfusion (LIR). Dexmedetomidine, an anesthetic adjunct, has been shown to have therapeutic effects on lung injury secondary to LIR. This study aimed to investigate the role of dexmedetomidine in ameliorating LIR-induced lung injury in a mouse model of bilateral hind LIR.MethodsIn this study, 75 mice were randomly divided into 5 groups to prepare the LIR model. After the model was established, arterial blood was extracted for blood gas analysis. The pathological changes of lung tissue, lung wet/dry weight ratio, arterial blood gas analysis, detection of myeloperoxidase (MPO) activity, the content of reactive oxygen species (ROS), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) in oxidative stress indexes, mitochondrial membrane potential (MMP), adenosine triphosphate (ATP) content and cytochrome c content were measured, and the relative protein expression levels of sirtuin-3 (SIRT3) and apoptosis factor Bcl-2 related X protein (Bax), B-cell Lymphoma 2 (Bcl-2), cleaved caspase 3, and nuclear factor erythroid 2-related factor 2 (Nrf2) and cytoplasmic heme oxygenase-1 (HO-1).ResultsPretreatment with dexmedetomidine dramatically ameliorated LIR-induced lung injury, the wet/dry weight ratio, the arterial blood gas parameters, and enhanced SIRT3 expression. Moreover, dexmedetomidine significantly inhibits ROS and MDA level and restores antioxidant enzyme activities (SOD, GSH-Px). Of note, dexmedetomidine suppressed LIR-induced lung tissue apoptosis by modulating apoptosis-associated protein such as Bax, Bcl-2, and cleaved caspase 3. Moreover, dexmedetomidine inhibited the LIR-induced decreases in MMP, ATP levels, and the release of cytochrome c of LIR to maintain mitochondrial function. Latest study has shown that activating Nrf2 could promote SIRT3 expression to alleviate IR injury. Intriguingly, dexmedetomidine could facilitate nuclear Nrf2 and cytoplasmic HO-1 expression.ConclusionsOur findings suggest that dexmedetomidine protects against LIR-induced lung injury by inhibiting the oxidative response, mitochondrial dysfunction and apoptosis. The mechanism appears to be at least partly mediated through the upregulation of SIRT3 expression.

Interplay of ZnONPs and/or SeNPs induces arsenic tolerance in soybean by regulation of antioxidants pool, WRKY genes, and expression of arsenic transporters

Arsenic is a nonessential element that confers toxicity to plants. Excessive arsenic accumulation in food crops poses safety concerns for human and animal health. To date, our understanding of the alleviation mechanism of As(V) toxicity in soybean plant employing NP is less known. Thus, the objective of the present study was to evaluate the effectiveness of zinc oxid nanoparticle (ZnONP) and/or selenium nanoparticle (SeNP) treatment on arsenic stress in seedling of soybean (Glycine max [L] Merrill). Soybean seedlings were grown hydroponically in 10 liters pots, treated at V2 growth stage with arsenate (25 μM L−1), two concentrations of ZnONPs (25 μM and 50 μM L−1) and two concentrations of elemental SeNPs (10 μM and 25 μM L−1) separately and in tandem, and then kept for further 10 d. Positive control (T2) significantly induced electrolyte leakage (EL) and facilitated the accumulation of O2− and H2O2 in roots and leaf tissues, along with higher deposition of As in sensitive cell organs including cellular organelles and cell wall. The application of ZnONPs and SeNPs, both independently and in tandem, promoted the As compartmentalization into vacuole, reduced the EL and rescued plant health by enhanced the metal tolerance index (MTI). In addition, cellular toxicants (i.e., O2−, H2O2 and GSSG) were drastically reduced because of the steady increased in MDHAR, GSTs, GSH and PCs levels in response to the nanoparticles treatment than in positive control (T2). Moreover, Na+ K+ -ATPase and Ca++ Mg++ -ATPase activities were also induced in response to NPs treatment groups. All the nanoparticles treatment groups displayed elevated expression of TFs (GmWRKY6, GmWRKY46, GmWRKY56, and GmWRKY106) particularly under 50 μM L−1 ZnONPs + 10 μM L−1 SeNPs (T8) compared to both negative (T1) and positive control (T2). More importantly, application of nanoparticles, both either independently or in tandem, decreased the expression of GmPT1, GmPT2, GmPT3, GmPT4 and GmPT8 with an exception of GmPT2 under SeNPs treatment group. Thus, the concurrent application of ZnONPs + SeNPs can be considered as eco-friendly fertilizer that will mimic As(V) toxicity and improve the growth and yield of soybean plants in As polluted areas.

Experimental and theoretical study of organic sensitizers for solid-state dye-sensitized solar cells (s-DSSCs)

The effect of a series of triarylamine based D-π-A organic dyes, namely RK1, BA504, BA741 and the simple L1 reference dye on solid-state dye sensitized solar cells (s-DSSCs) performances was studied. The solid hole transporting material (HTM) was obtained by in-situ photoelectrochemical polymerization (in-situ PEP) process applied in two different media (water and acetonitrile) to produce the poly-3,4 ethylenedioxythiophene (PEDOT) conducting polymer (CP). A joint experimental and theoretical (density functional theory and time-dependent density functional theory) study is conducted to correlate the dye molecular structure containing different donor, π-bridge or acceptor with several physicochemical characteristics such as optical (absorption and emission), electronic and redox properties of dyes in organic and aqueous medium; in-situ PEP process and charge transfer kinetics at the DSSC interfaces (Dye/TiO2 and Dye/HTM) through the alignment of the different energy levels of the dyes and electrodes. These properties are considered since they govern the performance of s-DSSCs denoted by the short-circuit current (Jsc), open circuit cell potential (Voc) and fill factor (FF). Among the four studied dyes, the s-DSSCs based on RK1, shows the best power conversion efficiency of 1.75% resulting from highest FF (0.57), Voc (550 mV) and Jsc (5.6 mA/cm2). The large differences in experimental photovoltaic performances of the obtained s-DSSCs have been well outlined and provide the guidelines for future development of more efficient solar-cell sensitizers.

Liver biopsy changes in fatal COVID 19 patients in a tertiary care hospital

COVID 19 is an ongoing pandemic that has horrified the entire globe. Aftermath of 2 wave is still a nightmare to many. Albeit not so sure of what’s in store, people in medical fraternity try their best to continue to study this virus, its effect and consequences in various organs. Lung being the prime victim followed by the heart has many scientific studies to substantiate its damage. Liver is a sensitive organ and it too has got affected directly by the virus or due to the drugs given irrespective of the ongoing previous liver disease if so any. We are a tertiary hospital in the field of gastrointestinal surgery. Hence we did a study on the patients who died due to COVID 19 associated diseases via a biopsy to understand more microscopically about the implication the dreadful virus has caused.

CLINICAL CASE OF COVID-ASSOCIATED GUILLAIN-BARRE SYNDROME

The aim of our article is to shed light on the problem of the development of Guillain-Barre syndrome after COVID-19 infection
 Materials and methods
 The main research methods we used were scientific research and the actual description of our own clinical case. Laboratory research methods, magnetic resonance imaging, and electromyography were used to confirm the diagnosis and perform differential diagnostics.
 Results.
 In 2021, the Center for Acute Neurology and Pain Treatment treated 12 patients with Guillain-Barre syndrome. Guillain-Barre syndrome (GBS) is an acute autoimmune inflammatory polyradiculoneuropathy. The clinical picture of GBS includes progressive motor and sensory disorders in the extremities and pain.
 We bring to your attention a clinical case of GBS in patient B., who was treated at the clinical hospital "Feofania". Patient B., 32 years old, was hospitalized in the Feofania Clinical Hospital with complaints of weakness in her arms and legs, inability to walk, foreign body sensation in the throat, difficulty swallowing, chest discomfort, and difficulty breathing. A few weeks before the disease, the patient was treated for a mild SARS-CoV-2 infection. The patient's condition gradually deteriorated by day 25 of the disease, despite plasmapheresis, intravenous immunoglobulin and glucocorticoid therapy. However, from day 29, the condition gradually improved and on re-examination after 2 months, the patient remained mild distal paresis of the leg muscles (up to 4 points), decreased tendon reflexes from the lower extremities. Disorders of sensitivity and function of the pelvic organs were not observed.
 Conclusion.
 In our article, we present a case of COVID-19-associated GBS with a classic clinical picture, increased peripheral paresis, stabilization, and gradual recovery of all functions (respiration, pelvic function, motor, sensory, and reflex) through pathogenetic treatment and follow-up rehabilitation measures.

L-arginine prevents ischemic injury in explanted rat intestinal regions in an ex vivo perfusion model

BackgroundThe small intestine is one of the most sensitive organs to ischemia. L-arginine has been shown to reduce damage from ischemia and reperfusion injury. We hypothesize that explanted intestinal segments from rats will demonstrate reduced susceptibility to ischemic injury when perfused with l-arginine. Methods45 small intestinal segments were harvested from male Sprague-Dawley rats and connected to an ex vivo intestinal perfusion device. Ischemic damage was induced by perfusing the extraluminal side with Ringer-HEPES buffer saturated with 100% N2. All segments were then perfused intraluminally with and without l-arginine. We conducted a set of experiments with intraluminal perfusion with both l-arginine and N-nitroarginine methyl ester (L-NAME), an inhibitor of the nitric oxide – arginine pathway. Control segments were perfused extraluminally under non-ischemic conditions and intraluminally with and without l-arginine. The intraluminal perfusate contained FITC-inulin, and the fluorescence signal of FITC-inulin was measured to calculate average fluid secretion, which directly corresponds to the extent of ischemic injury. ResultsIntestinal segments perfused with l-arginine had significantly decreased secretion over time in comparison to intestinal segments perfused without l-arginine (p<0.0001). Perfusion with L-NAME abrogated the protective effect of l-arginine. ConclusionIntraluminal perfusion with l-arginine reduced ischemic damage to harvested intestine.

Sensitizers designed toward efficient intramolecular charge separation for p-type dye-sensitized solar cells

Effective charge separation is demonstrated as one of the rational design strategies for organic sensitizers of both n-type and p-type dye-sensitized solar cells. Herein, we report the design and synthesis of novel D-A dye cTPAPh-NO2 and D-A1-A2 dye cTPABT-PyCN2 using triphenylamine as the donor, di-carboxylic acid group as anchoring group. Photophysical and electrochemical properties of both dyes were investigated to discuss the effect of anchoring group and molecular structure on the photophysical processes and charge separation feature of the sensitizers. For D-A dyes, the attachment of carboxyl groups reduces both the light harvesting and intramolecular charge separation ability of cTPAPh-NO2. In comparison, cTPABT-PyCN2 exhibits weak fluorescence and efficient intramolecular charge separation characteristics. Exceeding 80% of cTPABT-PyCN2 singlets decays via intramolecular electron transfer from the first acceptor to the dicyanovinyl pyrimidine. Finally, these synthesis dyes were used as sensitizers in p-type DSSCs and cTPABT-PyCN2 showed the overall power conversion efficiency of 0.103%, which is comparable to that of reported dyes. The results demonstrate that D-A1-A2 structure can be a promising strategy to design p-type sensitizers with effective charge separation characteristics.

Induction of oxidative stress upon low level exposure of arsenic using lipid peroxidation assay in freshwater fish Channa punctatus

Elevated level of arsenic exposure through drinking water induces noticeable change in the level of oxidative stress parameter such as lipid peroxidation. However, there is paucity of available information at low level exposure of arsenic for inducing oxidative damage. Present work was undertaken to investigate the oxidative stress inducing potential of arsenic at its low level exposure in fresh water fish Channa puntatus using lipid peroxidation, an established biomarker of oxidative stress. Fish specimen were exposed to 10, 50 (low level exposure) and 500μgL-1(high level exposure) of arsenic using sodium arsenite as a test substance. Samples of gill, liver, kidney and brain tissues were collected after 14 days of exposure and the lipid peroxidation assay was performed through the quantification of malondialdehyde (MDA) by TBARS assay for determination of oxidative damage in different tissues of fish. Significant increased levels of LPO were observed in all the organs. The present study showed that gills were the most sensitive organ, therefore, showed maximum peroxidative damage at 500 μgL-1 of arsenic exposure.

Protective Effect of Hydrogen Sulfide on Cerebral Ischemia-Reperfusion Injury.

The brain is the most sensitive organ to hypoxia in the human body. Hypoxia in the brain will lead to damage to local brain tissue. When the blood supply of ischemic brain tissue is restored, the damage will worsen, that is, cerebral ischemia-reperfusion injury. Hydrogen sulfide (H2S) is a gaseous signal molecule and a novel endogenous neuroregulator. Indeed, different concentrations of H2S have different effects on neurons. Low concentration of H2S can play an important protective role in cerebral ischemia-reperfusion injury by inducing anti-oxidative stress injury, inhibition of inflammatory response, inhibition of cell apoptosis, reduction of cerebrovascular endothelial cell injury, regulation of autophagy, and other ways, which provides a new idea for clinical diagnosis and treatment of related diseases. This review aims to report the recent research progress on the dual effect of H2S on brain tissue during cerebral ischemia/reperfusion injury.

Theoretical exploration of 1,3-Indanedione as electron acceptor-cum-anchoring group for designing sensitizers towards DSSC applications

The present work highlights the DFT and TD-DFT calculations of a few organic sensitizers designed based on a new electron-acceptor, 1,3-indanedione, which is a well-known electron-acceptor for designing new electron donor–acceptor molecules. Nine organic sensitizers (GR1-9) have been designed based on a modified 1,3-indanedione electron-acceptor and conventional electron-donor moieties. Optimization studies reveal that all dyes have twisted configurations, and therefore, the aggregation on the TiO2 semiconductor is expected to be less. GR2 dye shows the smallest energy gap, 2.43 eV, as compared to others which indicates an effective electronic excitation and injection. The dyes’ energy levels are compatible with the conduction band of TiO2 and redox potentials of the redox couple. Thermodynamic parameters indicate that the GR1, GR2, and GR5 dyes regenerate at a faster rate as compared to the other dyes. Further, NBO calculations demonstrate the dipolar nature of the designed molecules. Electronic spectra of dyes were red-shifted by 18–29 nm in acetonitrile solvent, which shifts further towards red-region upon adsorbing on to titania. The absorption spectrum of the GR1@TiO2 system shows a remarkable shift, 92 nm, and extends to the NIR region. The electron density of LUMO and LUMO + 1 is majorly confined to TiO2 moiety upon binding, which indicates complete electron donation from dye to the TiO2. Overall, our studies reveal that the 1,3-indanedione skeleton has the potential to serve as an electron-acceptor in designing new organic sensitizers for DSSCs. Therefore by conjugating conventional electron-donors with the 1,3-indanedione electron-acceptor, a new class of organic sensitizers can perhaps be synthesized for DSSC applications.

Effects of Microwave Radiation on Human Brain: The Positives and Negatives

Several RF sources are present for the commercial as well as defense application. In this article we will focus on the neurological consequences of Microwave Radiation (MWR). Since microwaves impact so many facets of our lives, this research focuses on their health implications. The brain is perhaps the most sensitive organ to MWR, with mitochondrial damage manifesting faster and more profoundly than in other regions. The effects of MWR on brain metabolic pathways have piqued public attention. The possibility for significant numbers of people to be subjected to dynamic, multi-frequency microwave energy nowadays, is a reality. Many urban people residing in the highrise structures of the city, come in the main beam radiation of the antenna which is mounted at a comparable height. Owing to the pervasive presence of MWR, its extensive usage, and the potential for harmful effects, comprehensive analyses of the health risks are imperative. It is crucial, therefore, to assess the level of exposure that is safe for the general population so as to minimize adverse effects despite reducing the favorable uses of microwaves.

Effects of Microwave Radiation on Human Brain: The Positives and Negatives

Several RF sources are present for the commercial as well as defense application. In this article we will focus on the neurological consequences of Microwave Radiation (MWR). Since microwaves impact so many facets of our lives, this research focuses on their health implications. The brain is perhaps the most sensitive organ to MWR, with mitochondrial damage manifesting faster and more profoundly than in other regions. The effects of MWR on brain metabolic pathways have piqued public attention. The possibility for significant numbers of people to be subjected to dynamic, multi-frequency microwave energy nowadays, is a reality. Many urban people residing in the highrise structures of the city, come in the main beam radiation of the antenna which is mounted at a comparable height. Owing to the pervasive presence of MWR, its extensive usage, and the potential for harmful effects, comprehensive analyses of the health risks are imperative. It is crucial, therefore, to assess the level of exposure that is safe for the general population so as to minimize adverse effects despite reducing the favorable uses of microwaves.

Oxidative Stress in Intestinal Ischemia-Reperfusion.

Ischemia-reperfusion (I/R) injury is a manifestation of tissue or organ damage that is followed by ischemia and exacerbated by the return of blood flow to a previously damaged tissue or organ. The intestines are one of the most sensitive tissues and organs to I/R injury. Moreover, the adverse consequences of intestinal I/R (II/R) injury are not limited to the intestine itself and can also lead to damage of the distant tissues and organs. The mechanism of II/R is extremely complex and oxidative stress is the key link in the pathogenesis of II/R injury. This study summarizes the roles of oxidative stress and its signaling pathways involved in II/R. The signaling pathways that mitigate II/R injury include the nuclear factor erythroid-related factor 2 (Nrf2)-mediated signaling pathway, Wnt/β-catenin pathway, and phosphatidylinositol kinase 3 (PI3K)/Akt pathway; those that aggravate II/R injury include the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway, Toll-like receptor (TLR) receptor-mediated signaling pathway, protein kinase CβII (PKCβII)/p66shc pathway, and microRNA (miRNA)/p66shc pathway; the effect of miRNA on related pathways and mitochondrial DNA translocation. The aforementioned pathways provide new ideas for further exploring the occurrence and development of II/R and more effective treatments for II/R injury.

The GARD™skin assay: Investigation of the applicability domain for metals.

New approach methodologies (NAMs) for hazard identification of skin sensitizing chemicals were adopted as test guidelines by the OECD during the last decade. These alternatives to animal models align to individual key events (KE) in the adverse outcome pathway (AOP) for skin sensitization for which the molecular initiating event (MIE) is covalent binding to proteins. As it currently stands, the AOP does not include mechanistic events of sensitization by metals, and limited information is available on whether NAMs accurately predict the sensitization potential of such molecules, which have been proposed to act via alternative mechanisms to organic chemicals. Methods for assessing the sensitization potential of metals would be valuable tools to support risk management within, e.g., occupational settings during production of new metal salts or within the medical device industry to evaluate leachables from metal alloys. This paper describes a systematic evaluation of the applicability domain of the GARD™skin assay for the assessment of metals. Hazard classifications were supplemented with an extended analysis of gene expression profiles induced by metal sensitizers to compare the induction of toxicity pathways between metals and organic sensitizers. Based on the results of this study, the accuracy, sensitivity, and specificity of GAR­D™skin for the prediction of skin sensitizing hazard were 92% (12/13), 100% (7/7), and 83% (5/6), respectively. Thus, the performance of GARD™skin for the assessment of metals was found to be similar to that observed for conventional organic substances, providing support for inclusion of metals within the applicability domain of the test method.

Enhanced Photovoltaic Performance of D-Π-A Organic Sensitizers by Simple Fluorination of Acceptor Unit

Enhanced Photovoltaic Performance of D-Π-A Organic Sensitizers by Simple Fluorination of Acceptor Unit

Assesment of radiotherapy effects on the blood flow in gingiva and dental pulp - a laser Doppler flowmetry study

This study aims to determine and compare the dental pulp and gingival blood flow in patients referred for oropharyngeal radiotherapy (RT) at three different time points: before the start, immediately after, and six months following the completion of RT. The aim is also to evaluate the dependence of the pulp and gingival blood flow on the radiation dose. A prospective study included 10 patients referred for intensity-modulated RT (IMRT) in the oropharyngeal region, with at least one intact tooth surrounded by a healthy gingiva. The dose received by each selected tooth and adjacent gingiva was determined according to the map of treatment planning and computer systems. The blood flow measurements were performed using the laser Doppler flowmetry (LDF) method. Comparing vascular flows at three different time points, the median blood flow in the dental pulp showed no statistically significant difference (p=0.325), contrary to gingiva (p=0.011). Immediately after RT completion, the gingival flow significantly increased compared to its starting point (p=0.012). The pulp flow correlated negatively with the radiation dose, whereas a strong correlation was noted 6 months following the RT completion. RT caused a significant acute gingival blood flow increase, followed by a long-term (over six months) tendency to return to the starting levels. The dental pulp blood flow is differently affected by higher radiation doses (over 50Gy) in comparison to lower doses (below 50Gy). During RT planning, considering the possibility of protecting the teeth localized near the Gross Tumor Volume as a sensitive organ is recommended.

Purely organic phosphor sensitization for efficiency improvement in yellow fluorescent organic light-emitting diodes

Utilization of a purely organic based room-temperature phosphorescent (RTPH) emitter as a sensitizer was studied by employing it in yellow fluorescent organic light-emitting diodes (OLEDs).

Monitoring the dependence of the photovoltaic properties of dye-sensitized solar cells from the structure of D–A–π–A-type sensitizers with a 9-(p-tolyl)-2,3,4,4a,9,9a-hexahydro-1H-1,4-methanocarbazole donor building block

The use of D–A–π–A organic sensitizers based on 9-(p-tolyl)-2,3,4,4a,9,9a-hexahydro-1H-1,4-methanocarbazole as a new donor building block for DSSCs made it possible to achieve the best power conversion efficiency of 5.68%.