Similar hypotensive responses to resistance exercise with and without blood flow restriction

Low intensity resistance exercise (RE) with blood flow restriction (BFR) has gained attention in the literature due to the beneficial effects on functional and morphological variables, similar to those observed during traditional RE without BFR, while the effects of BFR on post-exercise hypotension remain unclear. The aim of the present study was to compare the blood pressure (BP) response of trained normotensive individuals to RE with and without BFR. In this cross-over randomized trial, eight male subjects (23.8 ± 4 years, 74 ± 3 kg, 174 ± 4 cm) completed two exercise protocols: traditional RE (3 x 10 repetitions at 70% one-repetition maximum [1-RM]) and low intensity RE (3 x 15 repetitions at 20% 1-RM) with BFR. Blood pressure measurements were performed after 15 min of seated rest (0), immediately after and 10 min, 20 min, 30 min, 40 min, 50 min and 60 min after the experimental sessions. Similar hypotensive effects for systolic BP (SBP) were observed for both protocols (P < 0.05) after exercise, with no differences between groups (P > 0.05) and no statistically significant difference for diastolic BP (P > 0.05). These results suggest that in normotensive trained individuals, both traditional RE and RE with BFR induce hypotension for SBP, which is important to prevent cardiovascular disturbances.     

Effects of general,specific and combined warm-up on explosive muscular performance

The purpose of this study was to compare the acute effects of general, specific and combined warm-up (WU) on explosive performance. Healthy male (n = 10) subjects participated in six WU protocols in a crossover randomized study design. Protocols were: passive rest (PR; 15 min of passive rest), running (Run; 5 min of running at 70% of maximum heart rate), stretching (STR; 5 min of static stretching exercise), jumping [Jump; 5 min of jumping exercises – 3x8 countermovement jumps (CMJ) and 3x8 drop jumps from 60 cm (DJ60)], and combined (COM; protocols Run+STR+Jump combined). Immediately before and after each WU, subjects were assessed for explosive concentric-only (i.e. squat jump – SJ), slow stretch-shortening cycle (i.e. CMJ), fast stretch-shortening cycle (i.e. DJ60) and contact time (CT) muscle performance. PR significantly reduced SJ performance (p =0.007). Run increased SJ (p =0.0001) and CMJ (p =0.002). STR increased CMJ (p =0.048). Specific WU (i.e. Jump) increased SJ (p =0.001), CMJ (p =0.028) and DJ60 (p =0.006) performance. COM increased CMJ performance (p =0.006). Jump was superior in SJ performance vs. PR (p =0.001). Jump reduced (p =0.03) CT in DJ60. In conclusion, general, specific and combined WU increase slow stretch-shortening cycle (SSC) muscle performance, but only specific WU increases fast SSC muscle performance. Therefore, to increase fast SSC performance, specific fast SSC muscle actions must be included during the WU.     

Site-specific sonoporation of human melanoma cells at the cellular level using high lateral-resolution ultrasonic micro-transducer arrays

We developed a new instrumental method by which human melanoma cells (LU1205) are sonoporated via radiation pressures exerted by highly-confined ultrasonic waves produced by high lateral-resolution ultrasonic micro-transducer arrays (UMTAs). The method enables cellular-level site-specific sonoporation within the cell monolayer due to UMTAs and can be applicable in the delivery of drugs and gene products in cellular assays. In this method, cells are seeded on the biochip that employs UMTAs for high spatial resolution and specificity. UMTAs are driven by 30-MHz sinusoidal signals and the resulting radiation pressures induce sonoporation in the targeted cells. The sonoporation degree and the effective lateral resolution of UMTAs are determined by performing fluorescent microscopy and analysis of carboxylic-acid-derivatized CdSe/ZnS quantum dots passively transported into the cells. Models representing the transducer-generated ultrasound radiation pressure, the ultrasound-inflicted cell membrane wound, and the transmembrane transport through the wound are developed to determine the ultrasound-pressure-dependent wound size and enhanced cellular uptake of nanoparticles. Model-based calculations show that the effective wound size and cellular uptake of nanoparticles increase linearly with increasing ultrasound pressure (i.e., at applied radiation pressures of 0.21, 0.29, and 0.40 MPa, the ultrasound-induced initial effective wound radii are 150, 460, and 650 nm, respectively, and the post-sonoporation intracellular quantum-dot concentrations are 7.8, 22.8, and 29.9 nM, respectively) and the threshold pressure required to induce sonoporation in LU1205 cells is ～0.12 MPa.     

Control of neuronal morphology by the atypical cadherin Fat3

Neurons receive signals through dendrites that vary widely in number and organization, ranging from one primary dendrite to multiple complex dendritic trees. For example, retinal amacrine cells (ACs) project primary dendrites into a discrete synaptic layer called the inner plexiform layer (IPL) and only rarely extend processes into other retinal layers. Here, we show that the atypical cadherin Fat3 ensures that ACs develop this unipolar morphology. AC precursors are initially multipolar but lose neurites as they migrate through the neuroblastic layer. In fat3 mutants, pruning is unreliable and ACs elaborate two dendritic trees: one in the IPL and a second projecting away from the IPL that stratifies to form an additional synaptic layer. Since complex nervous systems are characterized by the addition of layers, these results demonstrate that mutations in a single gene can cause fundamental changes in circuit organization that may drive nervous system evolution.     

The high viscosity encountered during freezing in glycerol solutions: effects on cryopreservation

The objective of this study was to determine the viscosity of the residual unfrozen solution that cells are exposed to during freezing in the presence of glycerol and use this to interpret some key aspects of cryopreservation. The viscosity of the glycerol-water binary system exceeded 1000 cP at -40 degrees C, whilst the viscosity of the ternary system, glycerol-water-NaCl, exceeded 100,000 cP at -55 degrees C. The effect of these high viscosities on the diffusion of water at a constant temperature during freezing and during cooling at different linear rates has been estimated. At rates of cooling faster than 100 degrees C min(-1) the diffusion distance during freezing was calculated to be less than 15 microm. Validation of the diffusion calculations was confirmed by examination of the ultrastructure of the freeze concentrated matrix in samples prepared at a range of cooling rates. At a critical rate of cooling, water diffusion becomes limited by the high viscosity and two phenomena, of relevance to cryobiology, occur: (1) the composition of the freeze concentrated matrix around cells deviates from that of the equilibrium phase diagram; and (2) the osmotic loss of water from cells is restricted. These factors are of particular relevance to an understanding of the response of cells such as spermatozoa, red blood cells, and bacteria cooled rapidly with glycerol as cryoprotectant.     

Serosurvey of free-ranging Amur tigers in the Russian Far East

Wild Amur tigers (Panthera tigris altaica, n=44) from the Russian Far East were tested for antibodies to feline leukemia virus, feline corona virus (FCoV), feline immunodeficiency virus, feline parvovirus (FPV), canine distemper virus (CDV), Toxoplasma gondii, and Bartonella henselae. Antibodies to FCoV, CDV, FPV, and T. gondii were detected in 43, 15, 68, and 42% of tigers, respectively. No differences were detected in antibody prevalence estimates between tigers captured as part of a research program and those captured to mitigate human-tiger conflicts. Domestic dogs (Canis familiaris) were tested as a potential source for CDV; 16% were vaccinated against CDV and 58% of unvaccinated dogs were antibody positive for CDV. A high percentage of tigers were exposed to potential pathogens that could affect the survival of this species. We recommend continued monitoring of wild tigers throughout Asia, development of standardized sampling and postmortem examination procedures, and additional research to better understand potential domestic and wild animal sources for these pathogens.