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Sustainable composite materials based on biopolymers and natural fibers have attracted remarkable consideration globally due to their tremendous potential for a variety of applications. However, the poor compatibility among the natural fibers and biopolymers causes the reduced mechanical properties of the biocomposites, limiting their application spectrum and acting as one of the major barriers to commercialization. Therefore, surface modification of fibers using chemicals has been explored by several authors. However, most of the chemicals used are hazardous to the environment when used commercially. In the current investigation, sustainable chemicals (sodium bicarbonate and borax) were used to modify the surface of the pineapple leaf fibers (PALFs). Untreated and treated PALF/polylactic acid biocomposites were manufactured using the commercial-scale injection molding machine. The selected chemical treatment strategies were found to be efficient for improving the strength, crystallinity, and thermal properties of pineapple leaf fiber (PALF). An improved adhesion among the fibers and matrix, enhanced strength (tensile, flexural, and impact), and modulus (tensile and flexural) of the biocomposites were also recorded after the treatment. A robust structure-property linkage for PALF and their biocomposites has also been developed.

Increased ecological awareness, as well as stringent laws and legislation by government agencies, have restricted the use of synthetic fibers as reinforcement. This cognizance shifted the interest of engineers and research fraternity toward the use of natural fibers as reinforcement in polymers to develop sustainable composites. The current experimental investigation deals with the extraction and characterization of ‘munja’ fibers, extracted from Saccharum munja grass. A novel method has been developed for extraction of fibers from the grass followed by extensive evaluation of its physical (structure, density, crystallinity), morphological (surface area, voids), chemical (surface chemistry, hydrophobicity), thermal (thermogravimetry, activation energy), and mechanical properties for its reinforcement potential in polymer matrix composites. Mechanical properties of extracted fibers have also been analyzed in terms of tensile strength and modulus using Weibull’s statistical approach. All the aspects have been discussed thoroughly for their contribution in defining the global characteristics of biocomposites. The obtained results substantiate that munja fibers have an enormous potential to be used as a reinforcement in biocomposites, which can be commercially exploited for engineering applications.

Somatostatin (SST), a growth hormone inhibitory peptide, is expressed in endocrine and non-endocrine tissues, immune cells and the central nervous system (CNS). Post-release from secretory or immune cells, the first most appreciated role that SST exhibits is the antiproliferative effect in target tissue that served as a potential therapeutic intervention in various tumours of different origins. The SST-mediated in vivo and/or in vitro antiproliferative effect in the tumour is considered direct via activation of five different somatostatin receptor subtypes (SSTR1-5), which are well expressed in most tumours and often more than one receptor in a single cell. Second, the indirect effect is associated with the regulation of growth factors. SSTR subtypes are crucial in tumour diagnosis and prognosis. In this review, with the recent development of new SST analogues and receptor-specific agonists with emerging functional consequences of signaling pathways are promising therapeutic avenues in tumours of different origins that are discussed.

The current research endeavor, explores the thermal, mechanical, and degradation behavior of alkaline treated banana fibers reinforced polypropylene composites. Composites incorporating BF (20% w: w) treated with NaOH (5% w: v) aqueous solution were developed using extrusion-injection molding processes. After chemical treatment, the tensile, flexural and impact strength of the composite increases by 3.8%, 5.17%, and 11.50%, respectively. Scanning electron microscope (SEM) observations of tested specimens confirm the fiber pull out and fiber fracture as the main reasons for failure of developed composites under tensile and impact loading. The specimens were exposed to two different environments, water immersion and soil burial for 5 weeks for the degradation studies. The degradation behavior of composites was measured in terms of variation in weight and mechanical properties (tensile, flexural, and impact). The maximum degradation in mechanical properties was observed for the composites buried under soil. The composite lost 7.69%, 12.06%, and 3.27% of tensile, flexural, and impact strength, respectively.

During brain development, neurite formation plays a critical role in neuronal communication and cognitive function. In the present study, we compared developmental changes in the expression of crucial markers that govern the functional activity of neurons, including somatostatin (SST), choline acetyltransferase (ChAT), tyrosine hydroxylase (TH), brain nitric oxide synthase (bNOS), gamma-aminobutyric acid (GABA), glutamic acid decarboxylase (GAD-65) and synaptic vesicle protein synaptophysin (SYP) in non-differentiated and retinoic acid (RA)-induced differentiated SH-SY5Y cells. We further determined the role of SST in regulating subcellular distribution and expression of neurotransmitters. Our results indicate that SST potentiates RA-induced differentiation of SH-SY5Y cells and involves regulating the subcellular distribution and expression of neurotransmitter markers and synaptophysin translocation to neurites in a time-dependent manner, anticipating the therapeutic implication of SST in neurodegeneration.

Somatostatin is involved in the regulation of multiple signaling pathways and affords neuroprotection in response to neurotoxins. In the present study, we investigated the role of Somatostatin-14 (SST) in cell viability and the regulation of phosphorylation of Collapsin Response Mediator Protein 2 (CRMP2) (Ser522) via the blockade of Ca2+ accumulation, along with the inhibition of cyclin-dependent kinase 5 (CDK5) and Calpain activation in differentiated SH-SY5Y cells. Cell Viability and Caspase 3/7 assays suggest that the presence of SST ameliorates mitochondrial stability and cell survival pathways while augmenting pro-apoptotic pathways activated by Aβ. SST inhibits the phosphorylation of CRMP2 at Ser522 site, which is primarily activated by CDK5. Furthermore, SST effectively regulates Ca2+ influx in the presence of Aβ, directly affecting the activity of calpain in differentiated SH-SY5Y cells. We also demonstrated that SSTR2 mediates the protective effects of SST. In conclusion, our results highlight the regulatory role of SST in intracellular Ca2+ homeostasis. The neuroprotective role of SST via axonal regeneration and synaptic integrity is corroborated by regulating changes in CRMP2; however, SST-mediated changes in the blockade of Ca2+ influx, calpain expression, and toxicity did not correlate with CDK5 expression and p35/25 accumulation. To summarize, our findings suggest two independent mechanisms by which SST mediates neuroprotection and confirms the therapeutic implications of SST in AD as well as in other neurodegenerative diseases where the effective regulation of calcium homeostasis is required for a better prognosis.

Obesity is one of the major social and health problems globally and often associated with various other pathological conditions. In addition to unregulated eating behaviour, circulating peptide-mediated hormonal secretion and signaling pathways play a critical role in food intake induced obesity. Amongst the many peptides involved in the regulation of food-seeking behaviour, somatostatin (SST) is the one which plays a determinant role in the complex process of appetite. SST is involved in the regulation of release and secretion of other peptides, neuronal integrity, and hormonal regulation. Based on past and recent studies, SST might serve as a bridge between central and peripheral tissues with a significant impact on obesity-associated with food intake behaviour and energy expenditure. Here, we present a comprehensive review describing the role of SST in the modulation of multiple central and peripheral signaling molecules. In addition, we highlight recent progress and contribution of SST and its receptors in food-seeking behaviour, obesity (orexigenic), and satiety (anorexigenic) associated pathways and mechanism.

G-protein coupled receptors (GPCRs) are cell surface proteins responsible for translating >80% of extracellular reception to intracellular signals. The extracellular information in the form of neurotransmitters, peptides, ions, odorants etc is converted to intracellular signals via a wide variety of effector molecules activating distinct downstream signaling pathways. All GPCRs share common structural features including an extracellular N-terminal, seven-transmembrane domains (TMs) linked by extracellular/intracellular loops and the C-terminal tail. Recent studies have shown that most GPCRs function as dimers (homo- and/or heterodimers) or even higher order of oligomers. Protein-protein interaction among GPCRs and other receptor proteins play a critical role in the modulation of receptor pharmacology and functions. Although ~50% of the current drugs available in the market target GPCRs, still many GPCRs remain unexplored as potential therapeutic targets, opening immense possibility to discover the role of GPCRs in pathophysiological conditions. This review explores the existing information and future possibilities of GPCRs as tools in clinical pharmacology and is specifically focused for the role of somatostatin receptors (SSTRs) in pathophysiology of diseases and as the potential candidate for drug discovery.

The biological effects of cannabinoids, the major constituents of the ancient medicinal plant Cannabis sativa (marijuana) are mediated by two members of the G-protein coupled receptor family, cannabinoid receptors 1 (CB1R) and 2. The CB1R is the prominent subtype in the central nervous system (CNS) and has drawn great attention as a potential therapeutic avenue in several pathological conditions, including neuropsychological disorders and neurodegenerative diseases. Furthermore, cannabinoids also modulate signal transduction pathways and exert profound effects at peripheral sites. Although cannabinoids have therapeutic potential, their psychoactive effects have largely limited their use in clinical practice. In this review, we briefly summarized our knowledge of cannabinoids and the endocannabinoid system, focusing on the CB1R and the CNS, with emphasis on recent breakthroughs in the field. We aim to define several potential roles of cannabinoid receptors in the modulation of signaling pathways and in association with several pathophysiological conditions. We believe that the therapeutic significance of cannabinoids is masked by the adverse effects and here alternative strategies are discussed to take therapeutic advantage of cannabinoids.

The equilibrium potential for GABA-A receptor mediated currents (EGABA) in neonatal central neurons is set at a relatively depolarized level, which is suggested to be caused by a low expression of K+/Cl- co-transporter (KCC2) but a relatively high expression of Na+-K+-Cl- cotransporter (NKCC1). Theta-burst stimulation (TBS) in stratum radiatum induces a negative shift in EGABA in juvenile hippocampal CA1 pyramidal neurons. In the current study, the effects of TBS on EGABA in neonatal and juvenile hippocampal CA1 neurons and the underlying mechanisms were examined. Metabotropic glutamate receptors (mGluRs) are suggested to modulate KCC2 and NKCC1 levels in cortical neurons. Therefore, the involvement of mGluRs in the regulation of KCC2 or NKCC1 activity, and thus EGABA, following TBS was also investigated. Whole-cell patch recordings were made from Wistar rat hippocampal CA1 pyramidal neurons, in a slice preparation. In neonates, TBS induces a positive shift in EGABA, which was prevented by NKCC1 antisense but not NKCC1 sense mRNA. (RS)-a-Methyl-4-carboxyphenylglycine (MCPG), a group I and II mGluR antagonist, blocked TBS-induced shifts in both juvenile and neonatal hippocampal neurons. While blockade of mGluR1 or mGluR5 alone could interfere with TBS-induced shifts in EGABA in neonates, only a combined blockade could do the same in juveniles. These results indicate that TBS induces a negative shift in EGABA in juvenile hippocampal neurons but a positive shift in neonatal hippocampal neurons via corresponding changes in KCC2 and NKCC1 expressions, respectively. mGluR activation seems to be necessary for both shifts to occur while the specific receptor subtype involved seems to vary.

Pain relief is the principal action of opioids. Somatostatin (SST), a growth hormone inhibitory peptide is also known to alleviate pain even in cases when opioids fail. Recent studies have shown that mice are prone to sustained pain and devoid of analgesic effect in the absence of somatostatin receptor 4 (SSTR4). In the present study, using brain slices, cultured neurons and HEK-293 cells, we showed that SSTR4 and δ-Opioid receptor (δOR) exist in a heteromeric complex and function in synergistic manner. SSTR4 and δOR co-expressed in cortical/striatal brain regions and spinal cord. Using cultured neuronal cells, we describe the heterogeneous complex formation of SSTR4 and δOR at neuronal cell body and processes. Cotransfected cells display inhibition of cAMP/PKA and co-activation of SSTR4 and δOR oppose receptor trafficking induced by individual receptor activation. Furthermore, downstream signaling pathways either associated with withdrawal or pain relief are modulated synergistically with a predominant role of SSTR4. Inhibition of cAMP/PKA and activation of ERK1/2 are the possible cellular adaptations to prevent withdrawal induced by chronic morphine use. Our results reveal direct intra-membrane interaction between SSTR4 and δOR and provide insights for the molecular mechanism for the anti-nociceptive property of SST in combination with opioids as a potential therapeutic approach to avoid undesirable withdrawal symptoms.

Long term depression (LTD) in the CA1 region of the hippocampus, induced with a 20-Hz, 30 s tetanus to Schaffer collaterals, is enhanced in sleep-deprived (SD) rats. In the present study, we investigated the role of metabotropic glutamate receptors (mGluRs), γ-aminobutyric acid (GABA) B receptors (GABA(B)-Rs) and N-methyl-D-aspartic acid receptors (NMDARs) in the LTD of the population excitatory postsynaptic potential (pEPSP). The requirement of Ca(2+) from L- and T-type voltage-gated calcium channels (VGCCs) and intracellular stores was also studied. Results indicate that mGluRs, a release of Ca(2+) from intracellular stores and GABA(B)-Rs are required for LTD. Interestingly, while mGlu1Rs seem to be involved in both short-term depression and LTD, mGlu5Rs appear to participate mostly in LTD. CGP 55845, a GABA(B)-R antagonist, partially suppressed LTD in normally sleeping (NS) rats, while completely blocking LTD in SD rats. Moreover, GS-39783, a positive allosteric modulator for GABA(B)-R, suppressed the pEPSP in SD, but not NS rats. Since both mGluRs and GABA(B)-Rs seem to be involved in the LTD, especially in SD rats, we examined if the receptor expression pattern and/or dimerization changed, using immunohistochemical, co-localization and co-immunoprecipitation techniques. Sleep-deprivation induced an increase in the expression of GABA(B)-R1 and mGlu1αR in the CA1 region of the hippocampus. In addition, co-localization and heterodimerization between mGlu1αR/GABA(B)-R1 and mGlu1αR/GABA(B)-R2 is enhanced in SD rats. Taken together, our findings present a novel form of LTD sensitive to the activation of mGluRs and GABA(B)-Rs, and reveal, for the first time, that sleep-deprivation induces alterations in the expression and dimerization of these receptors.

Selective degeneration of medium spiny neurons and preservation of medium sized aspiny interneurons in striatum has been implicated in excitotoxicity and pathophysiology of Huntington's disease (HD). However, the molecular mechanism for the selective sparing of medium sized aspiny neurons and vulnerability of projection neurons is still elusive. The pathological characteristic of HD is an extensive reduction of the striatal mass, affecting caudate putamen. Somatostatin (SST) positive neurons are selectively spared in HD and Quinolinic acid/N-methyl-D-aspartic acid induced excitotoxicity, mimic the model of HD. SST plays neuroprotective role in excitotoxicity and the biological effects of SST are mediated by five somatostatin receptor subtypes (SSTR1-5).To delineate subtype selective biological responses we have here investigated changes in SSTR1 and 5 double knockout mice brain and compared with HD transgenic mouse model (R6/2). Our study revealed significant loss of dopamine and cAMP regulated phosphoprotein of 32 kDa (DARPP-32) and comparable changes in SST, N-methyl-D-aspartic acid receptors subtypes, calbindin and brain nitric oxide synthase expression as well as in key signaling proteins including calpain, phospho-extracellular-signal-regulated kinases1/2, synapsin-IIa, protein kinase C-α and calcineurin in SSTR1/5(-/-) and R6/2 mice. Conversely, the expression of somatostatin receptor subtypes, enkephalin and phosphatidylinositol 3-kinases were strain specific. SSTR1/5 appears to be important in regulating NMDARs, DARPP-32 and signaling molecules in similar fashion as seen in HD transgenic mice.This is the first comprehensive description of disease related changes upon ablation of G- protein coupled receptor gene. Our results indicate that SST and SSTRs might play an important role in regulation of neurodegeneration and targeting this pathway can provide a novel insight in understanding the pathophysiology of Huntington's disease.

Sustainable composite materials based on biopolymers and natural fibers have attracted remarkable consideration globally due to their tremendous potential for a variety of applications. However, the poor compatibility among the natural fibers and biopolymers causes the reduced mechanical properties of the biocomposites, limiting their application spectrum and acting as one of the major barriers to commercialization. Therefore, surface modification of fibers using chemicals has been explored by several authors. However, most of the chemicals used are hazardous to the environment when used commercially. In the current investigation, sustainable chemicals (sodium bicarbonate and borax) were used to modify the surface of the pineapple leaf fibers (PALFs). Untreated and treated PALF/polylactic acid biocomposites were manufactured using the commercial-scale injection molding machine. The selected chemical treatment strategies were found to be efficient for improving the strength, crystallinity, and thermal properties of pineapple leaf fiber (PALF). An improved adhesion among the fibers and matrix, enhanced strength (tensile, flexural, and impact), and modulus (tensile and flexural) of the biocomposites were also recorded after the treatment. A robust structure-property linkage for PALF and their biocomposites has also been developed. [ABSTRACT FROM AUTHOR]

Increased ecological awareness, as well as stringent laws and legislation by government agencies, have restricted the use of synthetic fibers as reinforcement. This cognizance shifted the interest of engineers and research fraternity toward the use of natural fibers as reinforcement in polymers to develop sustainable composites. The current experimental investigation deals with the extraction and characterization of 'munja' fibers, extracted from Saccharum munja grass. A novel method has been developed for extraction of fibers from the grass followed by extensive evaluation of its physical (structure, density, crystallinity), morphological (surface area, voids), chemical (surface chemistry, hydrophobicity), thermal (thermogravimetry, activation energy), and mechanical properties for its reinforcement potential in polymer matrix composites. Mechanical properties of extracted fibers have also been analyzed in terms of tensile strength and modulus using Weibull's statistical approach. All the aspects have been discussed thoroughly for their contribution in defining the global characteristics of biocomposites. The obtained results substantiate that munja fibers have an enormous potential to be used as a reinforcement in biocomposites, which can be commercially exploited for engineering applications. [ABSTRACT FROM AUTHOR]

Nowadays, the research fraternity across the globe is putting incredible efforts toward the development of sustainable materials. During this endeavor, the potential of sustainable biocomposites incorporating natural fibers as reinforcement and biopolymers as the matrix has received widespread attention for addressing the challenges associated with synthetic fibers and petroleum-derived polymers. However, the limited information about the processing guidelines for these materials and the lack of scientific evidence on how the processing routes affect the performance of the fabricated composites have limited their usage in several commercial applications. In the current investigation, three manufacturing routes, direct-injection molding (DIM) without compounding; compounding using extrusion followed by injection molding (EIM); and compounding using extrusion followed by compression molding (ECM) have been adopted to develop pineapple fibers (PFs)/poly-lactic acid (PLA) biocomposites. The investigation revealed that the crystallinity, visco-elastic, and mechanical responses of the composites fabricated by EIM significantly dominate the composites fabricated by DIM and ECM. The microstructural analysis confirms the severe attrition of fibers during ECM. The thermal analysis of the fabricated composites established that the important responses; glass transition, crystallization, and melting temperature, are independent of the choice of the manufacturing process. [ABSTRACT FROM AUTHOR]

The current research endeavor, explores the thermal, mechanical, and degradation behavior of alkaline treated banana fibers reinforced polypropylene composites. Composites incorporating BF (20% w: w) treated with NaOH (5% w: v) aqueous solution were developed using extrusion-injection molding processes. After chemical treatment, the tensile, flexural and impact strength of the composite increases by 3.8%, 5.17%, and 11.50%, respectively. Scanning electron microscope (SEM) observations of tested specimens confirm the fiber pull out and fiber fracture as the main reasons for failure of developed composites under tensile and impact loading. The specimens were exposed to two different environments, water immersion and soil burial for 5 weeks for the degradation studies. The degradation behavior of composites was measured in terms of variation in weight and mechanical properties (tensile, flexural, and impact). The maximum degradation in mechanical properties was observed for the composites buried under soil. The composite lost 7.69%, 12.06%, and 3.27% of tensile, flexural, and impact strength, respectively. [ABSTRACT FROM AUTHOR]

In the present experimental investigation, biocomposites based on short banana fiber (20 wt%) and poly-lactic acid were fabricated using three different processing techniques, namely direct injection molding (DIM), extrusion injection molding (EIM) and extrusion compression molding (ECM). The thermal and mechanical characterization as well as dynamic mechanical analysis has been performed to understand and compare the performance of the developed biocomposites. FTIR analysis has been conducted to investigate the presence and type of interfacial interaction in the biocomposites. XRD analysis was conducted to investigate the structure and to measure the crystallinity of the biocomposites. A significant improvement in the mechanical (tensile and flexural properties), dynamic mechanical properties (storage modulus, loss modulus, and tan delta) and crystallinity of the biocomposites fabricated by EIM were observed. A novel approach was used to examine the orientation and distribution of the fibers within the developed biocomposites. The fiber damage in terms of breaking, bending, twisting and formation of the clusters have been observed. Scanning Electron Microscopy (SEM) analysis revealed that the fiber pull-out and fracture are dominating the failure of biocomposite under loading. [ABSTRACT FROM AUTHOR]

Abstract Ageing behavior is one of the crucial factor for selection of material by designers and engineers, mainly for structural applications. Investigation of the ageing effect on biocomposites would supplement current knowledge and may help in encouraging their uses in real life applications. The current experimental investigation aims to determine the variation in various properties of Bagasse fibers reinforced Poly Lactic Acid (PLA) biocomposites during accelerated thermal ageing. Specimens of biocomposite were fabricated and exposed to temperature cycles of −20 °C and 65 °C (12 h each) for 12 weeks and characterized after every 4 weeks of exposure. Tensile and flexural properties exhibited steady improvement on exposure up to 8 weeks, followed by a reduction after ageing for 12 weeks. It can be concluded from X-ray diffraction (XRD) and dynamic mechanical analysis (DMA) that significant change in crystalline and glass transition behavior happens during the exposure period. Highlights • Bagasse fiber reinforced Poly (Lactic Acid) based biocomposites has been developed using Extrusion – Injection process. • The specimens have been subjected to two extremes of temperature in a cycle for a period of 12 weeks. • The effect on mechanical properties, density and surface roughness has been studied after every 4 weeks of exposure duration. • X ray diffraction and dynamic mechanical analysis have been performed to analyze the change in crystalline behavior. [ABSTRACT FROM AUTHOR]