Comparison of water and terrestrial jumping in natural and robotic insects.

Jumping requires high actuation power for achieving high speed in a short time. Especially, organisms and robots at the insect scale jump in order to overcome size limits on the speed of locomotion. As small jumpers suffer from intrinsically small power output, efficient jumpers have devised various ingenuous schemes to amplify their power release. Furthermore, semi-aquatic jumpers have adopted specialized techniques to fully exploit the reaction from water. We review jumping mechanisms of natural and robotic insects that jump on the ground and the surface of water, and compare the performance depending on their scale. We find a general trend that jumping creatures maximize jumping speed by unique mechanisms that manage acceleration, force, and takeoff duration under the constraints mainly associated with their size, shape, and substrate.

Underwater maneuvering of robotic sheets through buoyancy-mediated active flutter.

Falling leaves flutter from side to side due to passive and intrinsic fluid-body coupling. Exploiting the dynamics of passive fluttering could lead to fresh perspectives for the locomotion and manipulation of thin, planar objects in fluid environments. Here, we show that the time-varying density distribution within a thin, planar body effectively elicits minimal momentum control to reorient the principal flutter axis and propel itself via directional fluttery motions. We validated the principle by developing a swimming leaf with a soft skin that can modulate local buoyancy distributions for active flutter dynamics. To show generality and field applicability, we demonstrated underwater maneuvering and manipulation of adhesive and oil-skimming sheets for environmental remediation. These findings could inspire future intelligent underwater robots and manipulation schemes.

Ladybird beetle-inspired compliant origami.

Origami can enable structures that are compact and lightweight. The facets of an origami structure in traditional designs, however, are essentially nondeformable rigid plates. Therefore, implementing energy storage and robust self-locking in these structures can be challenging. We note that the intricately folded wings of a ladybird beetle can be deployed rapidly and effectively sustain aerodynamic forces during flight; these abilities originate from the geometry and deformation of a specialized vein in the wing of this insect. We report compliant origami inspired by the wing vein in ladybird beetles. The deformation and geometry of the compliant facet enables both large energy storage and self-locking in a single origami joint. On the basis of our compliant origami, we developed a deployable glider module for a multimodal robot. The glider module is compactly foldable, is rapidly deployable, and can effectively sustain aerodynamic forces. We also apply our compliant origami to enhance the energy storage capacity of the jumping mechanism in a jumping robot.

SP prevents T2DM complications by immunomodulation.

Type 2 diabetic mellitus (T2DM) is characterized by systemic inflammation and insulin resistance due to obesity, and this leads to critical complications, including retinopathy and nephropathy. This study explored the therapeutic effect of substance-p (SP), a neuropeptide, on T2DM progression and its complications. To examine whether SP affects glucose metabolism, lipid metabolism, systemic inflammation, and retinopathy, Otsuka Long-Evans Tokushima Fatty rats (OLETF, 27 weeks old) with chronic inflammation, obesity, and impaired bone marrow stem cell pool was selected. SP was intravenously injected and its effect was evaluated at 2 and 4 weeks after the SP injection. OLETF had typical symptoms of T2DM, including obesity, chronic inflammation, and poor glycemic control. However, SP treatment inhibited the body-weight gain and reduced circulating levels of free fatty acid, cholesterol, and triglyceride, ameliorating the obese environment. SP could suppress inflammation and rejuvenate bone marrow stem cell in OLETF rats. SP-mediated metabolic/immunological change could resolve hyperglycemia and insulin resistance. Histopathological analysis confirmed that SP treatment alleviated the dysfunction of target tissue with insulin resistance. OLETF rats have retinal damage from 27 weeks of age, which was reliably aggravated at 31 weeks. However, SP treatment could restore the damaged retina, sustaining its structure similarly to that of non-diabetic rats. In conclusion, systemic application of SP is capable contribute to the inhibition of the progression of T2DM and diabetic retinopathy.

Substance P promotes the recovery of oxidative stress-damaged retinal pigmented epithelial cells by modulating Akt/GSK-3ß signaling.

PURPOSE: Senescence of the retina causes an accumulation of reactive oxygen species (ROS). Oxidative stress associated with ROS can damage RPE cells, leading to neovascularization and severe ocular disorders, including age-related macular degeneration (AMD). Thus, the early treatment of the damage caused by oxidative stress is critical for preventing the development of ocular diseases such as AMD. In this study, we examined the role of substance P (SP) in the recovery of RPE cells damaged by oxidative stress. METHODS: To induce oxidative stress, RPE cells were treated with H2O2 at various doses. Recovery from oxidative stress was studied following treatment with SP by analyzing cell viability, cell proliferation, cell apoptosis, and Akt/glycogen synthase kinase (GSK)-3ß activation in RPE cells in vitro. RESULTS: H2O2 treatment reduced cellular viability in a dose-dependent manner. SP inhibited the reduction of cell viability due to H2O2 and caused increased cell proliferation and decreased cell apoptosis. Cell survival under oxidative stress requires the activation of Akt signaling that enables cells to resist oxidative stress-induced damage. SP treatment activated Akt/GSK-3ß signaling in RPE cells, which were damaged due to oxidative stress, and the inhibition of Akt signaling in SP-treated RPE cells prevented SP-induced recovery. Pretreatment with the neurokinin 1 receptor (NK1R) antagonist reduced the recovery effect of SP on damaged RPE cells. CONCLUSIONS: SP can protect RPE cells from oxidant-induced cell death by activating Akt/GSK-3ß signaling via NK1R. This study suggests the possibility of SP as a treatment for oxidative stress-related diseases.

Pharmacokinetic comparisons of two acetyl-L-carnitine formulations in healthy Korean volunteers.

BACKGROUND: Acetyl-L-carnitine (ALC) has demonstrated neuroprotective effects in several experiments and is widely prescribed to reduce cognitive impairment in Alzheimer's disease patients or manage neuropathic symptoms in diabetic patients. OBJECTIVES: This study was designed to assess the pharmacokinetic (PK) bioequivalence between a new generic (test) formulation of ALC hydrochloride 590 mg and a branded (reference) formulation of ALC hydrochloride 590 mg in healthy Korean male volunteers. METHODS: This was a randomizedsequence, single-dose, two-way crossover study. All subjects randomly received one formulation of the test or reference tablet and the other formulation with a 7-day washout period. Blood samples (7 mL) were collected immediately before dosing, and at 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 6, 8, and 12 hours postdose. The plasma concentrations of ALC were analyzed using liquid chromatography tandem mass spectrometry. Tolerability was assessed throughout the study. RESULTS: The PK profiles of both formulations showed similar rends. The mean (±SD) baseline (predose) concentration of ALC was 1.23±0.31 µg/mL and 1.09±0.30 µg/mL for the test and the reference formulations, respectively. The mean Cmax for the test and reference formulations were 1.74±0.43 µg/mL and 1.68±0.48 µg/mL, respectively. The mean AUClast of ALC was 12.96±1.89 µg×h/mL and 12.49±2.44 µg×h/mL for the test and reference formulations, respectively. The geometric mean ratios of test/reference (90% CI) were 1.050 (0.960-1.149) for Cmax and 1.048 (1.000-1.099) for AUClast. Both formulations were well tolerated in all treatment groups. CONCLUSION: The test and the reference formulations of ALC were bioequivalent with regard to the PK parameters.