Comparison of the acute effects of ankle bathing versus moderate-intensity aerobic exercise on vascular function in young adults.

We examined the efficacy of ankle bathing versus aerobic exercise to improve vascular function in young adults who were randomized to aerobic exercise (AE) (n = 13, 40%-60% of heart rate reserve), ankle bathing (AB) (n = 15, 43 °C), or a control condition (CON) (n = 14, ankle bathing, 36 °C) for 40 min. Conduit vessel function [brachial artery flow-mediated dilation (FMD)], carotid and femoral artery blood flow and shear rate (SR), and arterial stiffness [carotid-to-femoral pulse wave velocity (cf-PWV), augmentation index (AIx@75), ß-stiffness index, and arterial compliance] were evaluated. Compared with CON, AE and AB increased FMD at 30 min and 90 min (interaction: p < 0.05); AB decreased carotid artery blood flow and SR at 30 min, while both AE and AB increased femoral artery blood flow and SR at 30 min and 90 min (interaction: p < 0.05); AE and AB decreased cf-PWV and AIx@75 at 30 min and 90 min (interaction: p < 0.05); and AE improved both carotid and femoral ß-stiffness index and arterial compliance, while AB reduced ß-stiffness index and increased arterial compliance only in the femoral artery (interaction: p < 0.05). These findings suggest that ankle bathing may serve as an alternative strategy for enhancing vascular function. Novelty: We observed similar improvements in conduit vessel function, femoral artery blood flow and shear rate, and arterial stiffness following ankle bathing and acute aerobic exercise in young adults. These findings have identified ankle bathing as a potential therapeutic strategy for enhancing vascular function, which may be particularly relevant for those with limited ability to engage in regular aerobic exercise.

PT320, Sustained-Release Exendin-4, Mitigates L-DOPA-Induced Dyskinesia in a Rat 6-Hydroxydopamine Model of Parkinson's Disease.

BACKGROUND: We previously demonstrated that subcutaneous administration of PT320, a sustained-release (SR) form of exendin-4, resulted in the long-term maintenance of steady-state exenatide (exendin-4) plasma and target levels in 6-hydroxydopamine (6-OHDA)-pretreated animals. Additionally, pre- or post-treatment with PT320 mitigated the early stage of 6-OHDA-induced dopaminergic neurodegeneration. The purpose of this study was to evaluate the effect of PT320 on L-3,4-dihydroxyphenylalanine (L-DOPA)-induced abnormal involuntary movements (AIMs) in the rat 6-OHDA model of Parkinson's disease. METHODS: Adult male Sprague-Dawley rats were unilaterally lesioned in the right medial forebrain bundle by 6-OHDA. L-DOPA and benserazide were given daily for 22 days, starting from 4 weeks after lesioning. PT320 was co-administered weekly for 3 weeks. AIM was evaluated on days 1, 16, and 22 after initiating L-DOPA/benserazide + PT320 treatment. Brain tissues were subsequently collected for HPLC measurements of dopamine (DA) and metabolite concentrations. RESULTS: L-DOPA/benserazide increased AIMs of limbs and axial as well as the sum of all dyskinesia scores (ALO) over 3 weeks. PT320 significantly reduced the AIM scores of limbs, orolingual, and ALO. Although PT320 did not alter DA levels in the lesioned striatum, PT320 significantly attenuated 6-OHDA-enhanced DA turnover. CONCLUSION: PT320 attenuates L-DOPA/benserazide-induced dyskinesia in a 6-OHDA rat model of PD and warrants clinical evaluation to mitigate Parkinson's disease in humans.

Pharmacokinetics of Exenatide in nonhuman primates following its administration in the form of sustained-release PT320 and Bydureon.

The time-dependent (30 min - day 84) plasma profile of PT320, a sustained-release (SR)-Exenatide formulation under clinical development for treatment of neurodegenerative disorders, was evaluated in nonhuman primates after a single subcutaneous dose and was compared to Bydureon. Exenatide release from PT320 exhibited a triphasic pharmacokinetic profile. An initial peak occurred at 3 hr post-administration, a secondary peak at 5 days, and achievement of Exenatide steady-state plasma levels from day 10-28. Systemic exposure increased across PT320 doses, and Exenatide levels were maintained above the therapeutic threshold prior to achieving a steady-state. In contrast, Exenatide release from Bydureon exhibited a biphasic profile, with an initial plasma peak at 3 hr, followed by a rapid decline to a sub-therapeutic concentration, and a gradual elevation to provide a steady-state from day 35-49. Exenatide total exposure, evaluated from the area under the time-dependent Exenatide concentration curve, was similar for equivalent doses of PT320 and Bydureon. The former, however, reached and maintained steady-state plasma Exenatide levels more rapidly, without dipping to a sub-therapeutic concentration. Both SR-Exenatide formulations proved well-tolerated and, following a well-regulated initial release burst, generated steady-state plasma levels of Exenatide, but with PT320 producing continuous therapeutic Exenatide levels and more rapidly reaching a steady-state.

Pharmacokinetics and efficacy of PT302, a sustained-release Exenatide formulation, in a murine model of mild traumatic brain injury.

Traumatic brain injury (TBI) is a neurodegenerative disorder for which no effective pharmacological treatment is available. Glucagon-like peptide 1 (GLP-1) analogues such as Exenatide have previously demonstrated neurotrophic and neuroprotective effects in cellular and animal models of TBI. However, chronic or repeated administration was needed for efficacy. In this study, the pharmacokinetics and efficacy of PT302, a clinically available sustained-release Exenatide formulation (SR-Exenatide) were evaluated in a concussive mild (m)TBI mouse model. A single subcutaneous (s.c.) injection of PT302 (0.6, 0.12, and 0.024 mg/kg) was administered and plasma Exenatide concentrations were time-dependently measured over 3 weeks. An initial rapid regulated release of Exenatide in plasma was followed by a secondary phase of sustained-release in a dose-dependent manner. Short- and longer-term (7 and 30 day) cognitive impairments (visual and spatial deficits) induced by weight drop mTBI were mitigated by a single post-injury treatment with Exenatide delivered by s.c. injection of PT302 in clinically translatable doses. Immunohistochemical evaluation of neuronal cell death and inflammatory markers, likewise, cross-validated the neurotrophic and neuroprotective effects of SR-Exenatide in this mouse mTBI model. Exenatide central nervous system concentrations were 1.5% to 2.0% of concomitant plasma levels under steady-state conditions. These data demonstrate a positive beneficial action of PT302 in mTBI. This convenient single, sustained-release dosing regimen also has application for other neurological disorders, such as Alzheimer's disease, Parkinson's disease, multiple system atrophy and multiple sclerosis where prior preclinical studies, likewise, have demonstrated positive Exenatide actions.

Author Correction: Post-treatment with PT302, a long-acting Exendin-4 sustained release formulation, reduces dopaminergic neurodegeneration in a 6-Hydroxydopamine rat model of Parkinson's disease.

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Post-treatment with PT302, a long-acting Exendin-4 sustained release formulation, reduces dopaminergic neurodegeneration in a 6-Hydroxydopamine rat model of Parkinson's disease.

We previously demonstrated that pretreatment with Exendin-4, a glucagon-like peptide-1 (GLP-1) receptor agonist, reduces 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) -mediated dopaminergic neurodegeneration. The use of GLP-1 or Exendin-4 for Parkinson's disease (PD) patients is limited by their short half-lives. The purpose of this study was to evaluate a new extended release Exendin-4 formulation, PT302, in a rat model of PD. Subcutaneous administration of PT302 resulted in sustained elevations of Exendin-4 in plasma for >20 days in adult rats. To define an efficacious dose within this range, rats were administered PT302 once every 2 weeks either before or following the unilaterally 6-hydroxydopamine lesioning. Pre- and post-treatment with PT302 significantly reduced methamphetamine-induced rotation after lesioning. For animals given PT302 post lesion, blood and brain samples were collected on day 47 for measurements of plasma Exendin-4 levels and brain tyrosine hydroxylase immunoreactivity (TH-IR). PT302 significantly increased TH-IR in the lesioned substantia nigra and striatum. There was a significant correlation between plasma Exendin-4 levels and TH-IR in the substantia nigra and striatum on the lesioned side. Our data suggest that post-treatment with PT302 provides long-lasting Exendin-4 release and reduces neurodegeneration of nigrostriatal dopaminergic neurons in a 6-hydroxydopamine rat model of PD at a clinically relevant dose.

A New Treatment Strategy for Parkinson's Disease through the Gut-Brain Axis: The Glucagon-Like Peptide-1 Receptor Pathway.

Molecular communications in the gut-brain axis, between the central nervous system and the gastrointestinal tract, are critical for maintaining healthy brain function, particularly in aging. Epidemiological analyses indicate type 2 diabetes mellitus (T2DM) is a risk factor for neurodegenerative disorders including Alzheimer's disease (AD) and Parkinson's diseases (PD) for which aging shows a major correlative association. Common pathophysiological features exist between T2DM, AD, and PD, including oxidative stress, inflammation, insulin resistance, abnormal protein processing, and cognitive decline, and suggest that effective drugs for T2DM that positively impact the gut-brain axis could provide an effective treatment option for neurodegenerative diseases. Glucagon-like peptide-1 (GLP-1)-based antidiabetic drugs have drawn particular attention as an effectual new strategy to not only regulate blood glucose but also decrease body weight by reducing appetite, which implies that GLP-1 could affect the gut-brain axis in normal and pathological conditions. The neurotrophic and neuroprotective effects of GLP-1 receptor (R) stimulation have been characterized in numerous in vitro and in vivo preclinical studies using GLP-1R agonists and dipeptidyl peptidase-4 inhibitors. Recently, the first open label clinical study of exenatide, a long-acting GLP-1 agonist, in the treatment of PD showed long-lasting improvements in motor and cognitive function. Several double-blind clinical trials of GLP-1R agonists including exenatide in PD and other neurodegenerative diseases are already underway or are about to be initiated. Herein, we review the physiological role of the GLP-1R pathway in the gut-brain axis and the therapeutic strategy of GLP-1R stimulation for the treatment of neurodegenerative diseases focused on PD, for which age is the major risk factor.

A novel L-ascorbic acid and peptide conjugate with increased stability and collagen biosynthesis.

L-ascorbic acid (Vitamin C) and peptide are both useful compounds for collagen biosynthesis in cosmeceuticals (cosmetic and pharmaceutical fields). The instability of these compounds, however, limit their application in these industries. In this report, we describe the development of a novel compound, Stabilized Ascorbyl Pentapeptide (SAP), which physically is much more stable than L-ascorbic acid in water. The inhibitory effects of this SAP compound on tyrosinase and melanin synthesis is comparable to that of L-ascorbic acid. Importantly, the SAP compound displays no cytotoxicity at a high concentration (5 mM). The ability of SAP to promote collagen biosynthesis is greater than that of L-ascorbic acid or the KTTKS peptide alone. Considering the in vitro stability and functional effects, our data strongly suggest that the SAP compound is a good candidate not only as a cosmetic ingredient, but also as a wound healing agent.

Design and efficient synthesis of novel ascorbyl conjugated peptide with high collagen biosynthesis stimulating effects.

Collagen is critical for skin strength and elasticity, and its degradation leads to wrinkles that accompany aging. Based emphasis on the aesthetics, we tried to make a new compound that can highly stimulate collagen biosynthesis and synthesized ascorbyl conjugated peptide that is a complex form connected by succinoyl linker. We conducted several in vitro and in vivo experiments to identify if the compound has a potent activity, comparing to the ascorbic acid only for collagen biosynthesis. Our in vitro and in vivo result identified that ascorbyl conjugated peptide can stimulate collagen biosynthesis in human dermis and is assumably stable in the rat skin extracts. In conclusion, we strongly suggest that ascorbyl conjugated peptide can be used as a main ingredient for cosmetic products as well as wound healing agents.

Development of peptide substrates for trypsin based on monomer/excimer fluorescence of pyrene.

An assay using fluorogenic peptides based on the monomer/excimer fluorescence features of pyrene was developed to measure the proteolytic activity of trypsin, a serine protease. Two pyrene moieties were incorporated into the respective N- and C-terminus of the peptides as (pyrene)-C-Xaa-C-(pyrene), where Xaa represents amino acid residues of 5-, 6-, 7-, or 8-mer containing the cleavage site of trypsin. The proteolytic cleavage of the substrates led to an increase in monomer fluorescence and a decrease in excimer fluorescence of pyrene. Kinetic parameters (k(cat) and K(m)) for the enzymatic hydrolysis of the substrates were successfully determined. The parameters are dependent on the chain length of the substrate and optimal catalytic activity was obtained with substrates that consisted of 9 or 10 amino acid residues. The present assay system is sensitive and the preparation of the substrate is very simple. We suggest that this method may be suitable for high-throughput screening and also applicable to the characterization of other proteases.