Acute effects of prolonged intermittent low-intensity isometric warm-up schemes on jump,sprint, and agility performance in collegiate soccer players

The aim of the present study was to compare the effects of different warm-up interventions on jump, sprint and agility performance in collegiate soccer players. Twenty-one healthy male college soccer players (age: 20.14 ± 1.65 years; body height: 179.9 ± 8.34 cm; body mass: 74.4 ± 13.0 kg; % body fat: 9.45 ± 4.8) participated in the study. Subjects underwent four different randomized warm-up protocols separated by at least 48 hours. The warm-up schemes were: 1. no conditioning contraction protocol (NCC); 2. dynamic stretching (DS); 3. prolonged intermittent low-intensity isometric exercise (ST); and, 4. ST with an additional external load equal to 30% of body weight (ST + 30% BW). All interventions were preceded by a general warm-up. Results from one-way repeated measures ANOVA demonstrated a significant difference in countermovement jump (CMJ) at F(3,60) = 10.2, ηρ² = 0.337, p < 0.01. Post hoc analysis revealed a significant difference in CMJ performance in DS when compared to NCC and ST + 30% BW. No significant difference in CMJ was observed between DS and ST. CMJ scores in NCC, ST, and ST + 30% BW were non-significant. There was a significant difference in speed; F(3, 60) = 6.61, ηρ² = 0.248, p < 0.01. Post hoc analysis revealed significantly better time in DS than NCC and ST. However, no difference in speed was observed between DS and ST + 30% BW. Similarly, speed was similar in NCC, ST and ST + 30% BW. A significant difference in agility performance was also observed; F(3, 60) = 24.1, ηρ²= 0.546, p < 0.01. Post hoc analysis revealed significantly greater performance gains in DS than NCC. No significant difference in agility was observed in DS, ST and ST + 30% BW. In conclusion, a prolonged intermittent low-intensity isometric protocol using bodyweight only showed similar benefits with dynamic stretching in countermovement jump performance. When the same isometric condition with additional load equal to 30% of bodyweight was applied, effects in speed and agility were similar to dynamic stretching.     

Tonoplast intrinsic protein isoforms as markers for vacuolar functions

Plant cell vacuoles may have storage or lytic functions, but biochemical markers specific for the tonoplasts of functionally distinct vacuoles are poorly defined. Here, we use antipeptide antibodies specific for the tonoplast intrinsic proteins alpha-TIP, gamma-TIP, and delta-TIP in confocal immunofluorescence experiments to test the hypothesis that different TIP isoforms may define different vacuole functions. Organelles labeled with these antibodies were also labeled with antipyrophosphatase antibodies, demonstrating that regardless of their size, they had the expected characteristics of vacuoles. Our results demonstrate that the storage vacuole tonoplast contains delta-TIP, protein storage vacuoles containing seed-type storage proteins are marked by alpha- and delta- or alpha- and delta- plus gamma-TIP, whereas vacuoles storing vegetative storage proteins and pigments are marked by delta-TIP alone or delta- plus gamma-TIP. In contrast, those marked by gamma-TIP alone have characteristics of lytic vacuoles, and results from other researchers indicate that alpha-TIP alone is a marker for autophagic vacuoles. In root tips, relatively undifferentiated cells that contain vacuoles labeled separately for each of the three TIPs have been identified. These results argue that plant cells have the ability to generate and maintain three separate vacuole organelles, with each being marked by a different TIP, and that the functional diversity of the vacuolar system may be generated from different combinations of the three basic types.     

Onion yield as affected by plant density,nitrogen level and loss of leaf area

Onion (Allium cepa) is an important horticulture crop because of its value as a food with a long shelf life being a relatively non-perishable product. It is very helpful to understand the growth response of the seeded onion crop to conduct appropriate field practices in attaining the highest or optimum yields. A three year field experiment was conducted using a variety of onion Valcatorce INTA, in a randomized block design with five replicates. Treatments were two plant densities and three rates of N application. The bulb growth followed a classical sigmoid curve. During the rapid growing period, the crop had the greatest leaf area (LA) with at least six leaves per plant. Increasing plant density increased yield in kg/ha, but decreased bulb size. Defoliating 40 to 60% of the LA had a significant impact on bulb production only at early growth stages. Late in the growing period, the remaining LA was apparently large enough for producing sufficient amounts of metabolites to feed new leaves, increasing their photosynthesis efficiency for the benefit of bulb production.     

Solution structure of regioselectively addressable functionalized templates: An NMR and restrained molecular dynamics investigation

Three cyclic peptides that are Regioselectively Addressable Functionalized Templates (RAFT) for use in protein de novo design have been investigated using a combination of nmr, restrained molecular dynamics, and CD spectroscopy. These peptides contain up to four selectively addressable sites (orthogonally protected lysine side chains) or have selectively addressable faces. The results show a common stable conformation for templates of this kind based on two type II β-turns and an associated β-sheet structure. A preferential orientation for the side chains is also demonstrated. The significance of these findings is discussed in the context of applications of RAFT that rely on their conformational rigidity and ability to present functionalities in a defined spatial arrangement. © 1996 John Wiley & Sons, Inc.     

The energetics and evolution of oxidoreductases in deep time

The core metabolic reactions of life drive electrons through a class of redox protein enzymes, the oxidoreductases. The energetics of electron flow is determined by the redox potentials of organic and inorganic cofactors as tuned by the protein environment. Understanding how protein structure affects oxidation–reduction energetics is crucial for studying metabolism, creating bioelectronic systems, and tracing the history of biological energy utilization on Earth. We constructed ProtReDox ( https://protein-redox-potential.web.app ), a manually curated database of experimentally determined redox potentials. With over 500 measurements, we can begin to identify how proteins modulate oxidation–reduction energetics across the tree of life. By mapping redox potentials onto networks of oxidoreductase fold evolution, we can infer the evolution of electron transfer energetics over deep time. ProtReDox is designed to include user-contributed submissions with the intention of making it a valuable resource for researchers in this field.     

Bioresponsive matrices in drug delivery

For years, the field of drug delivery has focused on (1) controlling the release of a therapeutic and (2) targeting the therapeutic to a specific cell type. These research endeavors have concentrated mainly on the development of new degradable polymers and molecule-labeled drug delivery vehicles. Recent interest in biomaterials that respond to their environment have opened new methods to trigger the release of drugs and localize the therapeutic within a particular site. These novel biomaterials, usually termed "smart" or "intelligent", are able to deliver a therapeutic agent based on either environmental cues or a remote stimulus. Stimuli-responsive materials could potentially elicit a therapeutically effective dose without adverse side effects. Polymers responding to different stimuli, such as pH, light, temperature, ultrasound, magnetism, or biomolecules have been investigated as potential drug delivery vehicles. This review describes the most recent advances in "smart" drug delivery systems that respond to one or multiple stimuli.     

Pharmacological profiles of peptide drug candidates for the treatment of Alzheimer's disease

Amyloid plaques in brain, composed of aggregates of amyloid-beta peptide, play a central role in the pathogenesis of Alzheimer's disease and represent a good target for treatment. We have shown previously that a 5-amino acid beta-sheet breaker peptide (iA beta 5p), end-protected, has the ability to induce a dramatic reduction in amyloid deposition in two different transgenic Alzheimer's models (Permanne, B., Adessi, C., Saborio, G. P., Fraga, S., Frossard, M.-J., Dewachter, I., Van Dorpe, J., Banks, W. A., Van Leuven, F., and Soto, C. (2002) FASEB J. 16, 860-862). The aim of this study was to evaluate the effect of chemical modifications of the peptide bonds at the metabolite cleavage sites on the pharmacological properties of iA beta 5p derivatives. Using a rational approach, peptide analogs were designed and tested for in vitro activity and enzymatic stability. One peptide analog containing a methyl group introduced at the nitrogen atom of one amide bond showed increased stability in vitro, a 10-fold higher in vivo half-life, and good brain uptake compared with iA beta 5p while maintaining a similar activity in vitro. Our results suggest that the pharmacological profile of beta-sheet breaker peptides can be improved to produce compounds with drug-like properties that might offer a new promise in the treatment of Alzheimer's disease.     

Lysine as helix C-capping residue in a synthetic peptide

The structure of the synthetic peptide CH₃CO (Leu-Ser-Leu-Leu-Leu-Ser-Leu)₃Lys-NH₂ in trifluoroethanol/water 60/40 (volume ratio) was characterized by two-dimensional nmr spectroscopy. The peptide, closely related to the amphiphilic helix models designed by W. F. DeGrado and co-workers to mimic protein ion channels [(1988) Science, Vol. 240, p. 1177–1181], folds into a regular helix spanning residues 1–20. Evidence for a helix C-terminal capping conformation, involving the terminal lysine residue, was observed from Overhauser effects and checked for consistency by restrained molecular dynamics simulations. The side-chain amino group of Lys22 forms a hydrogen bond with the carbonyl of Leu18, and the distorted helical geometry of the terminal dipeptide allows the inclusion of a water bridge between the backbone NH of the Lys22 residue and the carbonyls of Leu19 and Ser20. © 1997 John Wiley & Sons, Inc.