Mitochondrial dysfunction and oxidative stress are two factors that are thought to play a significant role in the development of PD. As seen in Fig. 1, rotenone and H2O2 both induced dose dependant decreases in cell viability in the TH1 transfected SH-SY5Y cells. The concentrations of rotenone and H2O2 needed to induce this change were higher than those noted in previous studies using the SHSY5Y cell line; this could be due to the transfection of TH1 within these cells incurring increased resistance to rotenone. This hypothesis is supported by our previous studies using the TH1 transfected SH-SY5Y cell line reporting an increased resistance to oxidative stress and treatment with 6-OHDA and H2O2.Cleavage of PARP-1 is commonly used as an index of apoptosis. In this study, treatment with rotenone and H2O2 both induced a dose dependent increase in PARP-1 cleavage indicating the occurrence of apoptosis. Interestingly while oxidative stress is thought to play a major role in cell death induced by both rotenone and H2O2, the two toxins had significantly different effects on TH expression. Rotenone induced an increase in TH expression within our SH-SY5Y cells, this is in contrast to previous studies that suggest rotenone treatment results in a decrease in TH expression in both animal models and cells.It should be emphasised, however, we measured TH protein only in the cells that were still attached to the bottom of the plate but not in the cells that had detached from the plates as these were removed with the media at the completion of rotenone treatment. Therefore, our results suggest that TH protein was increased only per remaining cell and not per total number of cells present at the beginning of the treatment. In contrast H2O2 had no effect on TH protein levels in the remaining cells, suggesting that while oxidative stress may play a role in rotenone induced cell death, the increase in TH seen was not induced by it. Rotenone is also thought to cause inhibition of the proteasome system,grow tent therefore it is possible that the levels of TH protein are increasing in these cells because breakdown and removal of the protein have been altered; however, this requires further investigation. Natural compounds with antioxidant and anti-inflammatory properties have become of interest with regards to PD as the current treatments are associated with harmful side effects.
Curcumin, cinnamon, hemp seed and Polygonum cuspidatum are all naturally occurring products that have been used in traditional Chinese medicine for many years.We found that pre-treatment of our SH-SY5Y cells with compounds isolated from these products did not have an effect on rotenone toxicity. This is in contrast to previous studies that have demonstrated the protective effect of curcumin against rotenone in SH-SY5Y cells.It should be noted that while both studies have utilised SH-SY5Y cells, our cells contain human TH1. Therefore, it is possible that the transfected TH1 and the increase in TH protein expression seen with rotenone treatment could be potentiating rotenone induced cell death and playing a role in our inability to protect against rotenone toxicity. As TH is the rate limiting enzyme in DA synthesis, it is possible that the increased TH protein expression in response to rotenone could have induced an increase in DA production. The increased DA could possibly accumulate within the cytoplasm of the cells and lead to increased oxidative stress, proteasomal inhibition and mitochondrial dysfunction that could be contributing to rotenone induced cell death. This hypothesis is similar to a popular hypothesis that suggests an involvement of hyper-activation of TH and DA production in early PD pathogenesis.Interestingly, the same compounds did display the ability to protect against H2O2 induced toxicity. In addition, all tested compounds also prevented the increase in PARP-1 cleavage seen with H2O2 treatment indicating a reduction in apoptosis and supporting the findings of the viability assay as well as the findings of previous studies that suggest the novel compounds possess antioxidant activity.Moreover a previous study has demonstrated the ability of cinnamaldehyde to modulate the release of catecholamines from a rat pheochromocytoma cell line,indicating this compound has the potential to not only be neuroprotective but may also further ease the symptoms of PD by promoting catecholamine release. While the in vitro antioxidant capabilities of these compounds have been demonstrated previously, this is the first study to demonstrate the neuroprotective properties of cinnamaldehyde, caffeoyltyramide and piceatannol glucoside in a dopaminergic cell line in response to H2O2. In summary, we demonstrated that the effect of rotenone on these cells is more complicated than just the induction of oxidative stress and suggest that perhaps TH may be involved. Curcumin, cinnamaldehyde, caffeoyltyramide and piceatannol glucoside successfully prevented H2O2 induced cell death, making this the first study to demonstrate the neuroprotective potential of these natural compounds in a SH-SY5Y cellular model of oxidative stress.
The combination of traditional and man-made fiber-reinforced composites provides many advantages in different areas of engineering and technology. The commonly used natural fibers in engineering fields are sugar palm, flax, sisal hemp, kenaf, and Abaca fibers. Incorporating natural fibers in high-strength synthetic fibers like carbon and Kevlar improves mechanical properties, namely, stiffness, toughness, moisture resistance. The properties of composite specimens have been enhanced due to addition of nanomaterials and lignocellulose fibers as reinforcement in composites.The properties of composites depend on the individual element characterization like matrix and fibers type, chemical properties of matrix and fibers. The hybrid reinforced polymer composite consists of natural and synthetic fibers with short fiber and random orientation and long fiber in mat form. In short and randomly oriented fiber-based composite, the sliced fibers are mixed in a fixed quantity of thermoplastic resin, melt mixer is used for homogeneous mixing. The product taken from the mixing chamber is a chunk form of fiber-based polymer composites. The small pieces of fiber/ matrix composites are obtained from different techniques: the pultrusion process and injection molding. The different research articles have been available based on the characteristic study of fiber-based composite by varying fibers and resins, fibers length. This type of chopped fiber-based composite fabrication can be used to reduce wastage because of small size of fibers, and also it is economical. The hybrid composite consists of two or more different fibers. Sid ika et al. found the experimental results such as impact, flexural, and tensile strengths of natural fibers, namely, Jute and Coir reinforced polypropylene resin composites. It has also been found from experimental results that variation of fiber content by weight fraction such as 25:75, 50:50, 75:25 in the overall loading fibers and the matrix content remains constant. Likewise, Ranjan et al. carried out research on hybrid fibers reinforced polylactic acid resin composite and found the results, namely, tensile, flexural, and impact strength. Additionally, the investigators observed that the strength of the Sisal/Banana fibers was reduced due to the presence of weak adhesive bonding between the fibers and polylactic acid. It creates lower-strength materials. Per z et al. reported the optimum strength and modulus obtained by varying the weight fraction of banana and coir fiber content in fiber-based composite. In addition, 15% of the coir fiber-reinforced polymer composite gives good impact properties, 10% of coir fiber reinforced polymer composites provide the best modulus and strength under the flexural and impact forces. Per z et al. reported a similar enhancement of results in impact strength.
Especially the coir fiber content contributed more to the improvement of impact properties in composite due to the following reason at higher fiber loading, it requires high energy to break the fibers or fiber pullouts high lingocellulosic content. The composite strength and modulus may be reduced at higher fiber loading due to the non-maintaining homogenous distribution of fiber content, which causes agglomeration in the region. The agglomeration region acts as a stress concentrated region, and it is responsible for the initial crack to the failures. The following are the disadvantages of the natural fibers, lower strength, weaker inter facial bonding, hydrophilic and hydrophobic nature of fiber and matrix, respectively. To enhance the mechanical properties of natural fiber reinforced polymer composites following ways can be adopted, i.e., fiber treatments, the addition of synthetic reinforcements, and coupling agents. The long fiber reinforced polymer matrixes have been made from prepregs or woven mats. The prepregs have formed by the melting and pressing fiber fabrics at high temperatures. The final form of long fiber reinforced polymer composite is formed by stacking the prepregs layer by layer. Kar dumen et al. reported the influence of stacking sequence on the mechanical properties by using woven flax and non-woven jute fiber reinforced on the polypropylene resin. They said additionally that the hybrid composite consists of non-woven jute covered by woven flax, which exhibits good strength. In contrast, the hybrid materials consist of woven flax covered by the non-woven jute, displaying good impact strength. Addition of the 10% glass fiber in jute fiber reinforced polypropylene composite has improved tensile and flexural strengths. Dan Mallam et al. fabricated the hybrid composite from the kenaf fiber and polypropylene terephthalate matrix; the two types of hybrid composite, namely woven interplay and interwoven. Amo g the two kinds of hybrid composite, the interwoven ply exhibit good tensile and flexural properties,grow tent complete kit while the woven interplay displays good impact properties. It is summarized from kinds of literature that the highest mechanical properties of the synthetic and natural fibers in Kevlar and Abaca fibers respectively, also very few works have been done in hybrid composites, however, no work has been carried out in the combinations of the Kevlar and Abaca.
Similarly, Glass and Hemp fibers also have specific advantages compared to other fibers. In this work, an attempt has been made to bring benefits of both synthetic and natural fibers in hybrid composites. The mechanical properties namely tensile, flexural, and impact testing, have been performed numerically and experimentally. Aba a, Hemp, Glass, and Kevlar fibers have been used to prepare the composite specimens. The hybrid composite materials consist of Glass/Abaca, Glass/Hemp, and Kevlar/Abaca.In this work, all four fibers, namely, Abaca, Hemp, Glass, and Kevlar fibers, were purchased in the form of long fiber. The thickness of the Abaca fiber is 0.35 mm, length is 200e300 mm, which is obtained from the stem of pseudostem of Musa sepientum. Yellowish Kevlar 49 grade with bidirectional woven fabric has been used, Hemp fibers, with the thickness of 0.08 mm and length of 15e35 mm have been used, Glass fiber in mat form, length of 6e12 mm and 0.01 mm diameter. All fibers were purchased from Vruksha composite, Chennai, Tamilnadu. The hybrid composites were fabricated by alternating natural and synthetic fibers into the matrix. In the present work, epoxy resin was used as a matrix material. The liquid resin is a colorless, highly viscous liquid, at 25 C the density and viscosity are 1.16 gm cm 3 and 900 cps, respectively. Harer is used to reduce the curing time, namely, Amine purchased from Bangalore-based company, namely, Naptha resin and chemicals. The natural fibers are purchased from Maruthi Peach Company, Tirupur district, Tamil Nadu, India. The synthetic fibers, namely Kevlar and Glass fibers, are purchased as yarns from Go Green products, Coimbatore, Tamilnadu, India, and weaved of fibers alternatively with 6.7 6.7 yarns per cm. The composite specimen is bidirectional, and the bulk and linear densities were used to calculate the cross-section of yarns. The cross sectional area of yarn is 0.015 cm2 . The area is calculated by dividing linear density by its bulk modulus. The density of the different fibers is listed in Table 1.The three different combinations of natural and synthetic fibers-based composites were prepared. The following loads were applied: tensile, flexural, and impact; then, results were reported. In each experiment, three times repeated and took the average value for the graph. A similar work has been carried out by Mohanavel et al., who characterize the mechanical properties of the hybrid composite, which consists of Glass, Jute, and Madar fibers. Also, they fabricated the hybrid composite with a similar type of stacking sequence, that is, the first and last layer was synthetic fibers, due to the lesser water-absorbing characteristics of the fibers.