Flavors of GPCR signaling bias.

GPCRs are inherently flexible molecules existing in an equilibrium of multiple conformations. Binding of GPCR agonists shifts this equilibrium. Certain agonists can increase the fraction of active-like conformations that predispose the receptor to coupling to a particular signal transducer or a select group of transducers. Such agonists are called biased, in contrast to balanced agonists that facilitate signaling via all transducers the receptor couples to. These biased agonists preferentially channel the signaling of a GPCR to particular G proteins, GRKs, or arrestins. Preferential activation of particular G protein or arrestin subtypes can be beneficial, as it would reduce unwanted on-target side effects, widening the therapeutic window. However, biasing GPCRs has two important limitations: a) complete bias is impossible due to inherent flexibility of GPCRs; b) receptor-independent functions of signal transducer proteins cannot be directly affected by GPCR ligands or differential receptor barcoding by GRK phosphorylation.

Efficient Delivery of Gold Nanoparticles and miRNA-33a Via Cationic PEGylated Niosomal Formulation to MCF-7 Breast Cancer Cells.

To overcome the challenges associated with the co-delivery of AuNPs (gold nanoparticles) and miRNA as an anti-breast cancer combination therapy, niosomal systems were developed using Span 60, cholesterol, and a cationic lipid (CTAB), and the formulations were optimized using Box-Behnken experimental design. The niosomal formulations with the smallest size were selected for further optimization of size, surface charge, entrapment efficiency, and stability. To achieve this, AuNPs and DSPE-PEG2000 (2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000)were added to the formulation. The optimized niosomal formulation could effectively encapsulate AuNPs with an entrapment efficiency of 34.49% ± 0.84 and a spherical particle size of 153.6 ± 4.62 nm. The incorporation of PEG and CTAB led to notable enhancements in the overall characteristics of the delivery system. To evaluate the effectiveness of the combination therapy, various assessments such as cytotoxicity, apoptosis, and gene expression properties were conducted. The results demonstrated that the combination delivery using the new C-PEG-Nio-AuNPs (cationic pegylated niosomal gold nanoparticles) system and miRNA had the lowest IC50, the highest apoptosis rate, and the most significant upregulation of miRNA and BAX/BCL2 expression in MCF-7 cell growth. In conclusion, this innovative co-delivery approach represents a promising breakthrough in the development of therapeutic agents for breast cancer treatment. By combining multiple therapeutic agents within a single delivery system, this method has the potential to enhance treatment efficacy, reduce side effects, and improve patient outcomes.

The protective effect of benfotiamine on gastric ulcers in male rats: an experimental study.

Gastric ulcers are a common gastrointestinal disorder associated with significant morbidity and mortality. It can also increase the risk of gastric cancer. This study aimed to investigate the effect of benfotiamine on experimentally-induced gastric ulcers in male rats. In this study, 30 Wistar male rats were divided randomly into six groups: control (normal), indomethacin, omeprazole, and treatment groups, including 50, 100, and 200 mg/kg of benfotiamine. Gastric ulcer was induced by indomethacin gavage. Omeprazole and different therapeutic doses of benfotiamine were administered for three days. Twenty-four hours after the last treatment, the rats were euthanized, and samples were collected.The results demonstrated that 100 and 200 mg/kg of benfotiamine treatment significantly improved indomethacin-induced gastric tissue damage. Moreover, benfotiamine at 100 and 200 mg/kg effectively attenuated the levels of pro-inflammatory cytokines IL-6 and TNF-α and oxidative stress markers MDA and ROS while increasing the antioxidant GSH. These findings suggest that benfotiamine's gastroprotective effects are mediated through its antioxidant and anti-inflammatory properties, which help mitigate the tissue damage and inflammatory response associated with indomethacin-induced gastric ulcers.However, further research is needed to elucidate the precise molecular mechanisms underlying these beneficial effects and to evaluate the potential therapeutic application of benfotiamine in clinical settings.

Nanohybrid Based on (Mn, Zn) Ferrite Nanoparticles Functionalized With Chitosan and Sodium Alginate for Loading of Curcumin Against Human Breast Cancer Cells.

This study reports on the synthesis of Mn1 - xZnxFe2O4 (Mn, Zn ferrite) magnetic nanoparticles (MNPs) as drug delivery carriers for effective therapeutic outcomes. The MNPs were prepared using the coprecipitation method, and their magnetic properties were investigated based on their composition. Among the compositions tested, Mn0.8Zn0.2Fe2O4 MNPs exhibited superparamagnetic properties with a saturation magnetization moment of 34.6 emu/g at room temperature (25°C). To enhance the water solubility of curcumin (Cur), known for its hydrophobic nature, it was successfully loaded onto alginate (Alg)/chitosan (Chit)@Mn0.8Zn0.2Fe2O4 nanoparticles (NPs). The nanocomposite was characterized by field emission scanning electron microscopy (FE-SEM) which revealed a particle size of approximately 20 nm. The crystalline structure of the NPs was analyzed using X-ray diffraction, while Fourier-transform infrared (FTIR), energy-dispersive X-ray, and map analysis techniques were employed for further characterization. In terms of drug release, there was an initial burst release of Cur (around 18%) within the first hour, followed by a slower release (approximately 61%) over the next 36 h. The anti-tumor properties of the Cur-loaded NPs were evaluated using the Methyl Thiazol Tetrazolium (MTT) assay and quantitative real-time polymerase chain reaction. The MTT assay confirmed a higher cytotoxic effect of Cur-loaded Alg/Chit@Mn0.8Zn0.2Fe2O4 NPs on the MCF-7 breast cancer cell line compared to free Cur, highlighting the significance of incorporating Cur into nano-sized carrier systems.

Rutin mitigates perfluorooctanoic acid-induced liver injury via modulation of oxidative stress, apoptosis, and inflammation.

Objectives: Perfluorooctanoic acid (PFOA) is a persistent organic pollutant (POP), broadly present in the environment. Due to long biological half-life, it is accumulated in the body, especially the liver, causing hepatocellular damage. This study was designed to assess the effects of rutin on PFOA-induced liver damage in rats. Materials and Methods: Male Wistar rats were exposed to PFOA (10 mg/kg/day) alone, or in combination with different doses of rutin (25, 50, and 100 mg/kg/day) by oral gavage for 4 weeks. Results: PFOA altered the levels of liver enzymes, induced a notable change in the tissue structure of the liver, caused some levels of mitochondrial dysfunction, and increased the expression of pro-apoptotic and pro-inflammatory genes. Co-treatment with rutin mitigated the PFOA-induced elevation of liver enzymes, histopathological defects, oxidative damage, and mitochondrial dysfunction. In addition, rutin declined the stimulatory effects of PFOA on the Bax: Bcl2 ratio and reduced the PFOA-induced gene expression of TNF-α, IL-6, NF-ƙB, and JNK. Conclusion: These findings suggest rutin as a protective agent for PFOA-induced liver injury, albeit the protection was partial. Possible mechanisms are inhibition of oxidative stress, mitochondrial dysfunction, and inflammatory response.

Taurine protects against perfluorooctanoic acid-induced hepatotoxicity via inhibition of oxidative stress, inflammatory, and apoptotic pathways.

We are constantly encountering with low doses of chemicals in everyday life rather than toxic doses at a time. So, ongoing low-dose exposures of environmental chemicals commonly encountered are very likely to cause an adverse health effects. Perfluorooctanoic acid (PFOA) is frequently used for production of an array of consumer products and industrial processes. The present study evaluated the underlying mechanisms of PFOA-induced liver damage and also potential protection by taurine. Male Wistar rats were exposed to PFOA alone and in combination with taurine (25, 50, and 100 mg/kg/day) by gavage for 4 weeks. Liver function tests as well as histopathological examinations were studied. Also, oxidative stress markers, mitochondrial function, and nitric oxide (NO) production in liver tissues were measured. In addition, the expression of apoptosis-related genes (caspase-3, Bax, and Bcl-2), inflammation-associated genes (TNF-α, IL-6, NF-B), and c-Jun-N-terminal kinase (JNK) were evaluated. Taurine significantly reversed serum biochemical and histopathological alterations in the liver tissue following exposure to PFOA (10 mg/kg/day). Similarly, taurine alleviated mitochondrial oxidative damage-induced by PFOA in the liver tissue. An increased Bcl2: Bax ratio with decrees in the expression level of caspase-3, and decreased expression of inflammatory markers (TNF-α and IL-6), NF-B, and JNK were also observed following the administration of taurine. These findings suggest a protective role of taurine against PFOA-induced hepatotoxicity via the inhibition of oxidative stress, inflammation, and apoptosis.

Antidepressant-Like Effects of Edaravone and Minocycline: Investigation of Oxidative Stress, Neuroinflammation, Neurotrophic, and Apoptotic Pathways.

Depression is a very common mental disorder and mechanism that is associated with mitochondrial dysfunction. In the present study, we examined the mechanisms of action of isolated brain mitochondria in rats with depression for the first time. This will help identify the mitochondrial protective pathways of the two drugs and shed light on new therapeutic goals for developing antidepressants. Forced swimming, tail suspension, and sucrose preference tests were used to assess depressive-like behaviors and the oxidative stress factors of brain tissue, and measure the gene expression of apoptotic and anti-apoptotic, neuroplasticity, and neuroinflammatory factors by RT-PCR and acetylcholinesterase (AChE) activity in brain tissue (hippocampus and prefrontal) and the serum levels of corticosterone and fasting blood sugar. The results showed that the separation of neonatal rats from their mothers induced depressive-like behaviors, weight loss, mitochondrial dysfunction, increased expression of genes involved in neuroinflammation, apoptosis, genes involved in the depressive process, and decreased expression of genes involved in mood in both the hippocampus and prefrontal cortex. Maternal separation increased serum corticosterone levels, caused dysfunction of the cholinergic system, and also increased AChE activity. Treatment with different concentrations of minocycline and edaravone (1, 20, and 50 mg/kg), 5MTHF, and citalopram for 14 days showed that these drugs improved depression-like behaviors and mitochondrial function. It also reduced the expression of genes involved in neuroinflammation, apoptosis, and depression and increased the expression of genes involved in mood. In conclusion, minocycline and edaravone have neuroprotective, mitochondrial protective, antioxidant, anti-inflammatory, and anti-apoptotic effects against depressive-like behaviors caused by chronic stress.

Venlafaxine HCl Encapsulated in Niosome: Green and Eco-friendly Formulation for the Management of Pain.

The goal of this experimentation was to increase the cutaneous absorption of venlafaxine HCl (VFX) encapsulated in a niosome (venlasosme) produced by an ultrasonic approach. The impact of the cholesterol:surfactant (Chol:Surf) proportion was examined to modify the venlasosme properties. Photon correlation spectroscopy, powder X-ray diffraction (PXRD), SEM, DSC, and ATR-FTIR spectroscopy were utilized to investigate the solid-state and morphology of VFX in the venlasosme. The studies revealed that increasing the level of Chol in the venlasosme increased the size of the particles. Alterations in the Chol to surfactant ratios (when Chol decreased from 2.5 to 0%) caused the zeta potential enhancement from 7.37 ± 0.67 to 15.53 ± 1.47 mV. The venlasosme with the highest cholesterol concentration (2.5%) had the highest encapsulation efficiency (approximately 63%). PXRD results revealed that VFX in venlasosme was in the amorphous form. The levels of VFX in the cutaneous layers and the receiver compartment were higher for the venlasosme gel than for VFX simple gel in the cutaneous permeability study and showed no cutaneous irritancy in rats. Furthermore, the venlasosme gel demonstrated significant antinociceptive and anti-inflammatory responses when compared to the control groups (VFX simple gel and diclofenac gel). The topical administration of the venlasosme gel also considerably increased the tail-flick and hot-plate response time when compared to the VFX simple gel, control groups, and diclofenac gel (p < 0.05). These findings suggest that niosomes can improve VFX efficacy as an antinociceptive and anti-inflammatory substance by improving the medicaments delivery to the specified site.

Structural basis of GPCR coupling to distinct signal transducers: implications for biased signaling.

Three classes of G-protein-coupled receptor (GPCR) partners - G proteins, GPCR kinases, and arrestins - preferentially bind active GPCRs. Our analysis suggests that the structures of GPCRs bound to these interaction partners available today do not reveal a clear conformational basis for signaling bias, which would have enabled the rational design of biased GRCR ligands. In view of this, three possibilities are conceivable: (i) there are no generalizable GPCR conformations conducive to binding a particular type of partner; (ii) subtle differences in the orientation of individual residues and/or their interactions not easily detectable in the receptor-transducer structures determine partner preference; or (iii) the dynamics of GPCR binding to different types of partners rather than the structures of the final complexes might underlie transducer bias.

Sodium arsenite accelerates D-galactose-induced aging in the testis of the rat: Evidence for mitochondrial oxidative damage, NF-kB, JNK, and apoptosis pathways.

Aging inhibits male reproductive function and can have an impact on fertility. This study elucidated the accelerating role of sodium arsenite (As3+) on D-galactose-induced reproductive aging in male rats. The rats in the study are divided into nine groups. Group I is young control. Group II is naturally aged 24-month-old rats, other animal groups received As3+ (0.5, 1, and 2 mg/kg/day, i.p.) and/or D-galactose (DG) (50 mg/kg/day, i.p.) for 8 weeks. Then, sperm parameters, histopathological manifestations, oxidative stress markers, and gene expression of inflammatory factors (TNF-α, IL-6, and NF-ƙB), apoptosis-related genes (Bcl-2 and Bax), and C-Jun N-terminal kinase (JNK) were evaluated in testis tissue. As3+ (1 and 2 mg/kg) induced significant changes in evaluated factors compared to control group. Co-treatment with DG and As3+ caused morphological changes as well as a significant decrease in sperm motility and count. In DG + As3+ group, histopathological changes were also more obvious. Moreover, as compared to the DG group, co-treated animals exhibited a significant increase in oxidant markers and a decrease in antioxidant levels. Accordingly, DG co-exposure with As3+ markedly enhances the expressions of TNF-α, IL-6, and NF-ƙB compared to DG alone. Likewise, in the testis of rats treated with As3 + plus DG compared to DG alone, there was up-regulation of Bax (pro-apoptotic), down-regulation of Bcl-2 (anti-apoptotic), and elevation of JNK expression. These findings suggest sodium arsenite as an accelerating cause for D-galactose-induced aging process in testis tissue.

Atorvastatin Entrapped Noisome (Atrosome): Green Preparation Approach for Wound Healing.

The present study aimed to formulate atorvastatin niosome (Atrosome) through an ultrasonic technique and to determine its contribution to the extent of wound healing in an animal model. The optimized Atrosome formulation (Atrosome-2) was stable at 4 °C for 3 months. Differential scanning calorimetry (DSC), ATR-Fourier transform infrared spectroscopy (ATR-FTIR), and powder X-ray diffraction (PXRD) analysis revealed that atorvastatin (ATR) was well encapsulated within the niosomes either in a stabilized amorphous form or a molecularly dispersed state. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscope (AFM) confirmed the spherical nature of the Atrosomes. The optimized formulation showed polydispersity index, particle size, drug encapsulation efficiency (EE%), and zeta potential of 0.457 ± 0.05, 196.33 ± 6.45 nm, 86.15 ± 0.58 %, and - 20.73 ± 0.98 mV, respectively. ATR release from the Atrosome gel followed the first-order kinetic model and showed no cytotoxicity in the in vitro cytotoxicity test. Cell viability (human foreskin fibroblast cell line) was nearly 99%. An excision wound model was also applied in male Wistar rats to examine the in vivo efficacy of the optimized formulation, followed by investigating malondialdehyde (MDA, an end-product of lipid peroxidation), superoxide dismutase (SOD, an endogenous antioxidant), hydroxyproline levels, and glutathione peroxidase (GPx) in skin tissue samples. MDA significantly decreased in the Atrosome gel group after 21 days, while GPx, SOD, and hydroxyproline levels demonstrated an increase. According to histological results, rats receiving Atrosomes were treated effectively faster when compared to the other formulation used.

Investigating green roofs' CO2 sequestration with cold- and drought-tolerant plants (a short- and long-term carbon footprint view).

In recent years, green roofs have become the subject of increasing interest because of their good aesthetic qualities, energy conservation, and ability to reduce thermal island effect and absorb greenhouse gases, especially carbon dioxide (CO2). Given the typically significant carbon emission of construction activities, adding any extra component to a structure increases the amount of carbon to be released during the execution stage. This also applies to green roofs, which require more materials and more extensive construction activities than traditional roofs. However, plants of green roofs absorb substantial amounts of CO2 during their lifetime, thus leaving both short- and long-term positive impacts on the building's carbon footprint. This study investigated the short- and long-term effects of green roofs on carbon footprint, as compared to conventional roofs. For this investigation, the CO2 uptake of eight plant species with suitable drought- and cold-resistant properties was measured by infrared gas analysis (IRGA), and the effect of green roof on the building's carbon footprint was analyzed using the software Design Builder. The results showed that building a green roof instead of a traditional roof increases the carbon emission of the construction process by 4.6 kg/m2 of roof area. Investigations showed that, under high light intensities (1500-2000 µmol/m2 s), Sedum acre L. has the best performance in compensating the extra carbon emission imposed on the construction process (in 264 days only). Under low light intensities (1000-1500 µmol/m2 s), Frankenia laevis showed the best increase in the amount of carbon uptake (2.27 kg/m2 year).

The effects of carvedilol, metoprolol and propranolol on cisplatin-induced kidney injury.

The ß-adrenoceptor blockers may have anti-oxidant properties or induce ß-arrestin recruitment beyond classical desensitization of receptor/G protein coupling, offering potential therapeutic benefits. Here, we investigated the effects of carvedilol, metoprolol and propranolol in an animal model of cisplatin-induced nephrotoxicity. Rats received the ß-blockers (3 or 12 mg/kg/day) with or without cisplatin, and kidney function was investigated using renal scintigraphy, histopathology, and serum variables. Metoprolol and propranolol as well as low-dose carvedilol did not alter kidney function, per se. Meanwhile, high-dose carvedilol reduced renal accumulation of Technetium-99m (99mTc)-labeled dimercaptosuccinic acid (99mTc-DMSA) without significant effect on other variables. Furthermore, low-dose carvedilol prevented cisplatin-induced reduction of tracer uptake, but high-dose of this drug aggravated the situation. In this regard, both low and high -doses of carvedilol significantly inhibited cisplatin effects on kidney histology, BUN and creatinine levels. Also, high-dose propranolol inhibited cisplatin adverse effects on radiotracer uptake, histological manifestations, BUN and creatinine levels, while metoprolol failed to cause a notable effect. Taken together, carvedilol and high-dose propranolol may offer potential benefits in cisplatin nephrotoxicity.

Evaluation of mitochondrial dysfunction due to oxidative stress in therapeutic, toxic and lethal concentrations of tramadol.

Tramadol (TR) is a centrally acting analgesic drug that is used to relieve pain. The therapeutic (0.1-0.8 mg/l), toxic (1-2 mg/l) and lethal (>2 mg/l) ranges were reported for TR. The present study was designed to evaluate which doses of TR can induce liver mitochondrial toxicity. Mitochondria were isolated from the five rats' liver and were incubated with therapeutic to lethal concentrations (1.7-600 µM) of TR. Biomarkers of oxidative stress including: reactive oxygen species (ROS), lipid peroxidation (LPO), protein carbonyl content, glutathione (GSH) content, mitochondrial function, mitochondrial membrane potential (MMP) and mitochondrial swelling were assessed. Our results showed that ROS and LPO at 100 µM and protein carbonylation at 600 µM concentrations of TR were significantly increased. GSH was decreased specifically at 600 µM concentration. Mitochondrial function, MMP and mitochondrial swelling decreased in isolated rat liver mitochondria after exposure to 100 and 300 µM, respectively. This study suggested that TR at therapeutic and toxic levels by single exposure could not induce mitochondrial toxicity. But, in lethal concentration (≥100 µM), TR induced oxidative damage and mitochondria dysfunction. This study suggested that ROS overproduction by increasing of TR concentration induced mitochondrial dysfunction and caused mitochondrial damage via Complex II and membrane permeability transition pores disorders, MMP collapse and mitochondria swelling.

Receptor-Arrestin Interactions: The GPCR Perspective.

Arrestins are a small family of four proteins in most vertebrates that bind hundreds of different G protein-coupled receptors (GPCRs). Arrestin binding to a GPCR has at least three functions: precluding further receptor coupling to G proteins, facilitating receptor internalization, and initiating distinct arrestin-mediated signaling. The molecular mechanism of arrestin-GPCR interactions has been extensively studied and discussed from the "arrestin perspective", focusing on the roles of arrestin elements in receptor binding. Here, we discuss this phenomenon from the "receptor perspective", focusing on the receptor elements involved in arrestin binding and emphasizing existing gaps in our knowledge that need to be filled. It is vitally important to understand the role of receptor elements in arrestin activation and how the interaction of each of these elements with arrestin contributes to the latter's transition to the high-affinity binding state. A more precise knowledge of the molecular mechanisms of arrestin activation is needed to enable the construction of arrestin mutants with desired functional characteristics.

The Role of Cyclooxygenase 2 in the Cognitive Impairment Induced by Alcohol or Stress in Rats.

BACKGROUND: Cognitive impairment is an unpleasant and progressive mental disorder characterized by learning and memory disabilities. Stress and alcohol are two known environmental factors that increase cognitive impairment. This study was designed to evaluate the relative role of cyclooxygenase 2 in alcohol or stress-induced cognitive impairment. MATERIALS AND METHODS: Male Wistar rats were randomly divided into groups with six rats in each. The groups included sham, control, alcohol (15% ethanol in drinking water), and restraint stress (restraint 6 h per day). Three separated groups received celecoxib at a dose of 20 mg/kg in addition to those listed above. The treatments continued daily for 28 days. The object recognition task (ORT) and Morris water maze (MWM) are used to evaluate the learning and memory. RESULTS: Alcohol or restrain stress significantly increased the time and distance needed to find the hidden platform in MWM. Furthermore, they decreased the recognition index in ORT compared to the control group. Administration of celecoxib significantly decreased the required time and traveled distance to reach the platform in alcohol-treated animals but not in the stress-exposed rats. Celecoxib also significantly increased the recognition index both in alcohol- or restraint stress-exposed animals. CONCLUSION: We found that either alcohol or restraint stress impairs memory in rats. In MWM, celecoxib improved the alcohol-induced memory impairment but could not show a reduction in memory deterioration due to restraint stress. In ORT, celecoxib reversed memory impairment due to both alcohol and restraint stress.

Low-dose angiotensin AT1 receptor ß-arrestin-biased ligand, TRV027, protects against cisplatin-induced nephrotoxicity.

BACKGROUND: Recruitment of ß-arrestin to G protein-coupled receptors (GPCRs), initially described to cause receptor desensitization, has recently been shown to take active roles in cell signaling. We investigated the effects of TRV027, an angiotensin AT1 receptor ß-arrestin-biased ligand, as well as losartan and valsartan on cisplatin-induced kidney injury. METHOD: Male Sprague-Dawley rats were treated with angiotensin receptor ligands (1 or 10 mg/kg/day) with or without cisplatin, and kidney variables were monitored using animal SPECT, histopathology, and serum parameters. RESULTS: TRV027, losartan, and valsartan did not alter renal dimercaptosuccinic acid (DMSA) uptake, histopathological manifestations of kidney injury, blood urea nitrogen (BUN), and creatinine or Na+ and K+ levels, per se. However, when rats co-treated with cisplatin and either of the AT1 receptor blockers at higher doses, we observed aggravation of cisplatin-induced reduction of radiotracer uptake but improvement of cisplatin-induced hypokalemia, and insignificant effect on histological findings. Furthermore, we noted an additional increase in cisplatin-induced augmentation of BUN and creatinine levels in cisplatin plus valsartan group. TRV027 (1 mg/kg/day) inhibited cisplatin adverse effects on radiotracer uptake, kidney histology, BUN, and creatinine as well as electrolyte levels, but it failed to produce protective effects at higher dose (10 mg/kg/day). CONCLUSION: Low-dose TRV027 may offer potential benefits in kidney injury due to cisplatin.

Biased signaling of G protein coupled receptors (GPCRs): Molecular determinants of GPCR/transducer selectivity and therapeutic potential.

G protein coupled receptors (GPCRs) convey signals across membranes via interaction with G proteins. Originally, an individual GPCR was thought to signal through one G protein family, comprising cognate G proteins that mediate canonical receptor signaling. However, several deviations from canonical signaling pathways for GPCRs have been described. It is now clear that GPCRs can engage with multiple G proteins and the line between cognate and non-cognate signaling is increasingly blurred. Furthermore, GPCRs couple to non-G protein transducers, including ß-arrestins or other scaffold proteins, to initiate additional signaling cascades. Receptor/transducer selectivity is dictated by agonist-induced receptor conformations as well as by collateral factors. In particular, ligands stabilize distinct receptor conformations to preferentially activate certain pathways, designated 'biased signaling'. In this regard, receptor sequence alignment and mutagenesis have helped to identify key receptor domains for receptor/transducer specificity. Furthermore, molecular structures of GPCRs bound to different ligands or transducers have provided detailed insights into mechanisms of coupling selectivity. However, receptor dimerization, compartmentalization, and trafficking, receptor-transducer-effector stoichiometry, and ligand residence and exposure times can each affect GPCR coupling. Extrinsic factors including cell type or assay conditions can also influence receptor signaling. Understanding these factors may lead to the development of improved biased ligands with the potential to enhance therapeutic benefit, while minimizing adverse effects. In this review, evidence for ligand-specific GPCR signaling toward different transducers or pathways is elaborated. Furthermore, molecular determinants of biased signaling toward these pathways and relevant examples of the potential clinical benefits and pitfalls of biased ligands are discussed.

Formation of nanosuspensions in bottom-up approach: theories and optimization.

BACKGROUND: Nanosuspensions, liquid dispersions with nanometer size distribution, are becoming trendy in pharmaceutical practice to formulate poorly water-soluble drugs and to enhance their bioavailability. Generally, nanosuspensions are produced in two main approaches; top-down or bottom-up. The former is based on size-reduction of large particles via milling or high pressure homogenization. The latter is focused on the mechanisms of nucleation and particle growth. METHODS: In this review, the critical factors influencing the kinetics or dynamics of nucleation and growth are discussed. Subsequently, the mechanisms of nanosuspension instability as well as strategies for stabilization are elaborated. Furthermore, the effects of stabilizers on key parameters of instability as well as the process of choosing an appropriate stabilizer is discussed. RESULTS: Steric and electrostatic stabilizations or combination of them is essential for nanosuspensions formulation to prevent coagulation. Accordingly, some characteristics of stabilizers play critical role on stability and optimization of nanosuspensions; i.e., HLB and concentration. Nevertheless, after reviewing various articles, it is ascertained that each formulation requires individual selection of surfactants according to the parameters of the particle surface and the medium. CONCLUSIONS: Based on the results, application of excipients such as stabilizers requires proper optimization of type and concentration. This implies that each formulation requires its own optimization process. Graphical Abstract ᅟ.

First Molecular Identification of Symbiotic Archaea in a Sponge Collected from the Persian Gulf, Iran.

BACKGROUND: Marine sponges are associated with numerically vast and phylogenetically diverse microbial communities at different geographical locations. However, little is known about the archaeal diversity of sponges in the Persian Gulf. The present study was aimed to identify the symbiotic archaea with a sponge species gathered from the Persian Gulf, Iran. METHODS: Sponge sample was collected from a depth of 3 m offshore Bushehr, Persian Gulf, Iran. Metagenomic DNA was extracted using a hexadecyl trimethyl ammonium bromide (CTAB) method. The COI mtDNA marker was used for molecular taxonomy identification of sponge sample. Also, symbiotic archaea were identified using the culture-independent analysis of the 16S rRNA gene and PCR- cloning. RESULTS: In this study, analysis of multilocus DNA marker and morphological characteristics revealed that the sponge species belonged to Chondrilla australiensis isolate PG_BU4. PCR cloning and sequencing showed that all of the sequences of archaeal 16S rRNA gene libraries clustered into the uncultured archaeal group. CONCLUSION: The present study is the first report of the presence of the genus of Chondrilla in the Persian Gulf. Traditional taxonomy methods, when used along with molecular techniques, could play a significant role in the accurate taxonomy of sponges. Also, the uncultured archaea may promise a potential source for bioactive compounds. Further functional studies are needed to explore the role of the sponge-associated uncultured archaea as a part of the marine symbiosis.