Resistance training alters the sensorimotor control of vasti muscles

The present study examined and compared two modes of weight training (bodybuilding and power-lifting) on the surface EMG of vasti muscles, knee joint position sense and isometric knee extension force in 48 able-bodied subjects. Subjects were randomly allocated into either a moderate loading and repetitions (bodybuilding) training or a high loading and low repetitions (power-lifting) training, or a no training control group. Training was conducted on alternate days with individual supervision. After 8 weeks of training, subjects from both training groups showed significantly earlier EMG onset timing and higher amplitude of vastus medialis obliquus relative to vastus lateralis (p = 0.005 or <0.001), and improved knee joint position sense (p < 0.001), but no such changes were found in the control group. However, the changes were not significantly different (p > 0.05) between the two training groups. The findings suggested that the neuromotor control of the vasti muscles could be altered by regular weight training.     

Resistance training enhances components of the insulin signaling cascade in normal and high-fat-fed rodent skeletal muscle.

Our laboratory recently reported that chronic resistance training (RT) improved insulin-stimulated glucose transport in normal rodent skeletal muscle, owing, in part, to increased GLUT-4 protein concentration (Yaspelkis BB III, Singh MK, Trevino B, Krisan AD, and Collins DE. Acta Physiol Scand 175: 315-323, 2002). However, it remained to be determined whether these improvements resulted from alterations in the insulin signaling cascade as well. In addition, the possibility existed that RT might improve skeletal muscle insulin resistance. Thirty-two male Sprague-Dawley rats were assigned to four groups: control diet (Con)-sedentary (Sed); Con-RT; high-fat diet (HF)-Sed; and HF-RT. Animals consumed their respective diets for 9 wk; then RT animals performed 12 wk of training (3 sets, 10 repetitions at 75% one-repetition maximum, 3x/wk). Animals remained on their dietary treatments over the 12-wk period. After the training period, animals were subjected to hindlimb perfusions. Insulin-stimulated insulin receptor substrate-1-associated phosphatidylinositol-3 kinase activity was enhanced in the red gastrocnemius and quadriceps of Con-RT and HF-RT animals. Atypical PKC-zeta/lambda and Akt activities were reduced in HF-Sed and normalized in HF-RT animals. Resistance training increased GLUT-4 protein concentration in red gastrocnemius and quadriceps of Con-RT and HF-RT animals. No differences were observed in total protein concentrations of insulin receptor substrate-1, Akt, atypical PKC-zeta/lambda, or phosphorylation of Akt. Collectively, these findings suggest that resistance training increases insulin-stimulated carbohydrate metabolism in normal skeletal muscle and reverses high-fat diet-induced skeletal muscle insulin resistance by altering components of both the insulin signaling cascade and glucose transporter effector system.     

Calmodulin enhances the stability of the estrogen receptor

The estrogen receptor mediates breast cell proliferation and is the principal target for chemotherapy of breast carcinoma. Previous studies have demonstrated that the estrogen receptor binds to calmodulin-Sepharose in vitro. However, the association of endogenous calmodulin with endogenous estrogen receptors in intact cells has not been reported, and the function of the interaction is obscure. Here we demonstrate by co-immunoprecipitation from MCF-7 human breast epithelial cells that endogenous estrogen receptors bind to endogenous calmodulin. Estradiol treatment of the cells had no significant effect on the interaction. However, incubation of the cells with tamoxifen enhanced by 5-10-fold the association of calmodulin with the estrogen receptor and increased the total cellular content of estrogen receptors by 1.5-2-fold. In contrast, the structurally distinct calmodulin antagonists trifluoperazine and CGS9343B attenuated the interaction between calmodulin and the estrogen receptor and dramatically reduced the number of estrogen receptors in the cell. Neither of these agents altered the amount of estrogen receptor mRNA, suggesting that calmodulin stabilizes the protein. This hypothesis is supported by the observation that, in the presence of Ca2+, calmodulin protected estrogen receptors from in vitro proteolysis by trypsin. Furthermore, overexpression of wild type calmodulin, but not a mutant calmodulin incapable of binding Ca2+, increased the concentration of estrogen receptors in MCF-7 cells, whereas transient expression of a calmodulin inhibitor peptide reduced the estrogen receptor concentration. These data demonstrate that calmodulin binds to the estrogen receptor in intact cells in a Ca2+-dependent, but estradiol-independent, manner, thereby modulating the stability and the steady state level of estrogen receptors.     

Behavioral management of epileptic seizures following EEG biofeedback training of the sensorimotor rhythm

Eight severely epileptic patients, four males and four females, ranging in age from 10 to 29 years, were trained to increase 12–14 Hz EEG activity from the regions overlying the Rolandic area. This activity, the sensorimotor rhythm(SMR), has been hypothesized to be related to motor inhibitory processes(Sterman, 1974). The patients represented a crosssection of several different types of epilepsy, including grand mal, myoclonic, akinetic, focal, and psychomotor types. Three of them had varying degrees of mental retardation. SMR was detected by a combination of an analog filtering system and digital processing. Feedback, both auditory and/or visual, was provided whenever one-half second of 12–14-Hz activity was detected in the EEG. Patients were provided with additional feedback keyed by the output of a 4–7-Hz filter which indicated the presence of epileptiform spike activity, slow waves, or movement. Feedback for SMR was inhibited whenever slow-wave activity spikes or movement was also present. During the treatment period most of the patients showed varying degrees of improvement. Two of the patients who had been severely epileptic, having multiple seizures per week, have been seizure free for periods of up to 1 month. Other patients have developed the ability to block many of their seizures. Seizure intensity and duration have also decreased. Furthermore, the successful patients demonstrated an increase in the amount of SMR and an increase in amplitude of SMR during the training period. Spectral analyses for the EEGs were performed periodically. The effectiveness of SMR conditioning for the control of epileptic seizures is evaluated in terms of patient characteristics and type of seizures.     

Encapsulation enhances protoplast fusant stability

A barrier to cost-efficient biomanufacturing is the instability of engineered genetic elements, such as plasmids. Instability can also manifest at the whole-genome level, when fungal dikaryons revert to parental species due to nuclear segregation during cell division. Here, we show that by encapsulating Saccharomyces cerevisiae-Pichia stipitis dikaryons in an alginate matrix, we can limit cell division and preserve their expanded metabolic capabilities. As a proxy to cellulosic ethanol production, we tested the capacity of such cells to carry out ethanologenic fermentation of glucose and xylose, examining substrate use, ploidy, and cell viability in relation to planktonic fusants, as well as in relation to planktonic and encapsulated cell cultures consisting of mixtures of these species. Glucose and xylose consumption and ethanol production by encapsulated dikaryons were greater than planktonic controls. Simultaneous co-fermentation did not occur; rather the order and kinetics of glucose and xylose catabolism by encapsulated dikaryons were similar to cultures where the two species were encapsulated together. Over repeated cycles of fed-batch culture, encapsulated S. cerevisiae-P. stipitis fusants exhibited a dramatic increase in genomic stability, relative to planktonic fusants. Encapsulation also increased the stability of antibiotic-resistance plasmids used to mark each species and preserved a fixed ratio of S. cerevisiae to P. stipitis cells in mixed cultures. Our data demonstrate how encapsulating cells in an extracellular matrix restricts cell division and, thereby, preserves the stability and biological activity of entities ranging from genomes to plasmids to mixed populations, each of which can be essential to cost-efficient biomanufacturing.     

Effects of a brief sensorimotor training on the development of behavioral inhibition in the mouse

In the young C57Bl6 mouse, the hyperexcitability phase (`pop-corn' stage) which normally occurs around the 16–18th postnatal day and lasts 3–6 days, was greatly shortened by an intensive sensorimotor training when the `pop-corn' stage appeared. It was prevented when the animals were trained for 4 days before it appeared. This might suggest, at least in part, that an early short duration sensorimotor training increased the rate of maturation of the inhibitory systems that sustain the development of the motor behavior.     

Metabolic adjustment enhances food web stability

Understanding ecosystem stability is one of the greatest challenges of ecology. Over several decades, it has been shown that allometric scaling of biological rates and feeding interactions provide stability to complex food web models. Moreover, introducing adaptive responses of organisms to environmental changes (e.g. like adaptive foraging that enables organisms to adapt their diets depending on resources abundance) improved species persistence in food webs. Here, we introduce the concept of metabolic adjustment, i.e. the ability of species to slow down their metabolic rates when facing starvation and to increase it in time of plenty. We study the reactions of such a model to nutrient enrichment and the adjustment speed of metabolic rates. We found that increasing nutrient enrichment leads to a paradox of enrichment (increase in biomasses and oscillation amplitudes and ultimately extinction of species) but metabolic adjustment stabilises the system by dampening the oscillations. Metabolic adjustment also increases the average biomass of the top predator in a tri‐trophic food chain. In complex food webs, metabolic adjustment has a stabilising effect as it promotes species survival by creating a large diversity of metabolic rates. However, this stabilising effect is mitigated in enriched ecosystems. Phenotypic plasticity of organisms must be considered in food web models to better understand the response of organisms to their environment. As metabolic rate is central in describing biological rates, we must pay attention to its variations to fully understand the population dynamics of natural communities.     

Changes in muscle coordination with training.

Three core concepts, activity-dependent coupling, the composition of muscle synergies, and Hebbian adaptation, are discussed with a view to illustrating the nature of the constraints imposed by the organization of the central nervous system on the changes in muscle coordination induced by training. It is argued that training invoked variations in the efficiency with which motor actions can be generated influence the stability of coordination by altering the potential for activity-dependent coupling between the cortical representations of the focal muscles recruited in a movement task and brain circuits that do not contribute directly to the required behavior. The behaviors that can be generated during training are also constrained by the composition of existing intrinsic muscle synergies. In circumstances in which attempts to produce forceful or high velocity movements would otherwise result in the generation of inappropriate actions, training designed to promote the development of control strategies specific to the desired movement outcome may be necessary to compensate for protogenic muscle recruitment patterns. Hebbian adaptation refers to processes whereby, for neurons that release action potentials at the same time, there is an increased probability that synaptic connections will be formed. Neural connectivity induced by the repetition of specific muscle recruitment patterns during training may, however, inhibit the subsequent acquisition of new skills. Consideration is given to the possibility that, in the presence of the appropriate sensory guidance, it is possible to gate Hebbian plasticity and to promote greater subsequent flexibility in the recruitment of the trained muscles in other task contexts.     

Resistance exercise training and the orthostatic response

Resistance exercise has been suggested to increase blood volume, increase the sensitivity of the carotid baroreceptor cardiac reflex response (BARO), and decrease leg compliance, all factors that are expected to improve orthostatic tolerance. To further test these hypotheses, cardiovascular responses to standing and to pre-syncopal limited lower body negative pressure (LBNP) were measured in two groups of sedentary men before and after a 12-week period of either exercise (n = 10) or no exercise (control, n = 9). Resistance exercise training consisted of nine isotonic exercises, four sets of each, 3 days per week, stressing all major muscle groups. After exercise training, leg muscle volumes increased (P < 0.05) by 4–14%, lean body mass increased (P = 0.00) by 2.0 (0.5) kg, leg compliance and BARO were not significantly altered, and the maximal LBNP tolerated without pre-syncope was not significantly different. Supine resting heart rate was reduced (P = 0.03) without attenuating the heart rate or blood pressure responses during the stand test or LBNP. Also, blood volume (¹²⁵I and ⁵¹Cr) and red cell mass were increased (P < 0.02) by 2.8% and 3.9%, respectively. These findings indicate that intense resistance exercise increases blood volume but does not consistently improve orthostatic tolerance. Accepted: 17 January 1997     

Evolutionary stability of vigilance coordination among social foragers

Coordination can greatly improve the efficiency of anti-predatory vigilance scans by increasing predator detection for a constant proportion of time spent vigilant. However, it has been rarely found in nature and most studies have detected or assumed independent scanning by group members. In this study, we analysed the functional consequences of the coordinated alternation of vigilance scanning by group foragers. We introduce coordination by assuming that interscan intervals (ISIs) follow a modified gamma distribution. Depending on the parameters of the distribution, successive scans can be evenly spaced (coordinated scanning) or may present a high overlap (uncoordinated scanning). Comparing evolutionarily stable strategies for animals that do not coordinate their scanning with animals that do coordinate their anti-predator behaviour shows that coordination has a marked effect on survival probability. Moreover, the coordinating strategy is quite robust against mutants that scan independently with exponential distributions of ISIs. However, coordination breaks down when animals can continuously adjust their level of coordination by deciding the proportion of time they spend monitoring the behaviour of other group members. In this case, coordination is only evolutionarily stable if it can be very easily achieved.     

Glycosylation enhances functional stability of the chemotactic cytokine CCL2

The human chemokine CCL2 gene was expressed in the yeast P.pastoris and gave rise to a mixture of differently glycosylated recombinant proteins. In comparison to non-glycosylated E.coli-derived CCL2, glycosylated yeast CCL2L was 4-20 times less active in a chemotactic assay in vitro. However, CCL2L could maintain full activity upon prolonged incubation at 37 degrees C, whereas the non-glycosylated chemokine readily lost activity. It could be hypothesized that glycosylation is a mechanism used by the organism to modulate CCL2 stability. The partial loss of specific activity due to glycosylation is balanced by the advantage of prolonging the effectiveness of chemokine. Thus, differential glycosylation allows one to obtain highly effective short-lived CCL2 or less-effective long-lived CCL2 and may thus represent a novel mechanism of adaptation to pathological versus physiological conditions.     

Drying pretreatment enhances the photosynthetic stability of alginate immobilisedPhormidium laminosum

Summary Immobilisation of the thermophilic cyanobacteriumP. laminosum in alginate beads with a drying pretreatment led to stabilization of the Photosystem II water splitting activity for at least 3 months. This was accompanied by an increase of energy transfer from phycobilins, a maintenance of the variable fluorescence and a red shift of 77k emissions of allophycocyanin and PSI complexes. These changes indicate improvements in the photosynthetic efficiencies of immobilised cells.Abbreviations PSI, II Photosystem I, II: Chl a: chlorophyll a - LHC light harvesting complex - DCP IP 2–6 dichlorophenol indophenol - DCMU 3(3,4-dichlorophenyl)-1,1 dimethylurea - IMPD 2, 3, 5, 6 tetramethyl phenylenediamine