Investigating wild berries as a dietary approach to reducing the formation of advanced glycation endproducts: chemical correlates of in vitro antiglycation activity.

Evidence supports the health promoting benefits of berries, particularly with regard to the prevention and management of chronic diseases such cardio- and cerebrovascular disease, diabetes and Alzheimer's disease. Two related pathophysiological features common to many of these conditions are oxidative stress and the accumulation of advanced glycation endproducts (AGEs). Whereas antioxidant properties are well-established in several species of berries and are believed central to their protective mechanisms, few studies have investigated the effects of berries on AGE formation. Here, employing a series of complementary in vitro assays, we evaluated a collection of wild berry extracts for 1) inhibitory effects on fluorescent-AGE and Nε- (carboxymethyl)lysine-albumin adduct formation, 2) radical scavenging activity and 3) total phenolic and anthocyanin content. All samples reduced AGE formation in a concentration-dependent manner that correlated positively with each extract's total phenolic content and, to a lesser degree, total anthocyanin content. Inhibition of AGE formation was similarly related to radical scavenging activities. Adding antiglycation activity to the list of established functional properties ascribed to berries and their phenolic metabolites, our data provide further insight into the active compounds and protective mechanisms through which berry consumption may aid in the prevention and treatment of chronic diseases associated with AGE accumulation and toxicity. As widely available, safe and nutritious foods, berries represent a promising dietary intervention worthy of further investigation.

Earth-referenced handrail contact facilitates interlimb cutaneous reflexes during locomotion.

The purpose of this study was to investigate whether the gating of interlimb cutaneous reflexes is altered by holding an earth-referenced handrail during locomotion. In the first experiment, subjects performed locomotor tasks of varying difficulty (level walking, incline walking, and stair climbing) while lightly holding an earth-referenced rail. In the second experiment, the extent of rail contact and nature of the rail stability (e.g., fixed vs. mobile rail) were varied while subjects performed incline walking. Cutaneous reflexes were evoked by delivering trains of electrical stimulation to the sural nerve at the ankle. EMG data were collected continuously from muscles in the upper and lower limbs and trunk. Results showed that modulation of reflexes across the body changed when the rail was held. Most interestingly, a facilitatory reflex in the shoulder extensor posterior deltoid emerged during swing phase only when subjects held a rail. This facilitatory reflex was largest during the more challenging tasks of incline walking and stair climbing, A similar reflex facilitation was observed in the elbow extensor triceps brachii. The observed facilitation of reflexes in triceps brachii and posterior deltoid was specifically expressed only when subjects held an earth-referenced rail. This suggests that interlimb reflexes in arm extensors may be enhanced to make use of a supportive handrail for stability during gait. Therefore, holding a rail may cause global changes in reflex thresholds across the body that may have widespread functional relevance for assisting in the maintenance of postural stability during locomotion.

Task-specific modulation of cutaneous reflexes expressed at functionally relevant gait cycle phases during level and incline walking and stair climbing.

Reflexes are exquisitely sensitive to the motor task that is being performed at the time they are evoked; in other words, they are "task-dependent". The purpose of this study was to investigate the extent to which the pattern of reflex modulation is conserved across three locomotor tasks that differ in muscle activity, joint kinematics, and stability demands. Subjects performed continuous level and incline walking on a treadmill and stair climbing on a stepping mill. Cutaneous reflexes were evoked by delivering trains of electrical stimulation to the sural nerve at the ankle at an intensity of two times the radiating threshold. Electromyographic (EMG) recordings were collected continuously from muscles in the arms, legs and trunk. Results showed that middle-latency reflex modulation patterns were generally conserved across the three locomotor tasks with a few notable exceptions related to specific functional requirements. For example, a reflex reversal was observed for tibialis anterior during stair climbing, which may be indicative of a specific adaptation to the task constraints. Overall our data suggest that the underlying neural mechanisms involved in coordinating level walking can be modified to also coordinate other locomotor tasks such as incline walking and stair climbing. Therefore, there may be considerable overlap in the neural control of different forms of locomotion.

Human gene expression as a tool to determine horticultural maturity in a bioactive plant (Echinacea purpurea L. Moench).

A phenological study was conducted to determine the impact of harvest maturity on the immune-modulating properties of Echinacea purpurea. The aerial parts of this plant were collected during seven stages of development and were assayed for a common botanical marker for this species, cichoric acid. Plants of selected development stages were also assayed for total polysaccharides and compared for their immune-modulating effects on the THP-1 monocyte/macrophage cell line by means of a gene expression study. Although the concentration of cichoric acid did not change significantly during the course of the study, stage 1 (advanced vegetative) had the highest concentration of total polysaccharides and exhibited the most potent induction activity on immune-modulating cytokines such as interferon-gamma and tumor necrosis factor-alpha. These findings suggest that the use of gene expression may be an effective tool not only to standardize botanical extracts but also to optimize harvest time.

Split-belt treadmill stepping in infants suggests autonomous pattern generators for the left and right leg in humans.

The behavior of the pattern generator for walking in human infants (7-12 months of age) was studied by supporting the infants to step on a split-belt treadmill. The treadmill belts could be run at the same speed (tied-belt), different speeds, or in different directions (split-belt). We determined whether the legs could operate independently under these conditions, as demonstrated by taking different numbers of steps or by stepping in different directions. Video, surface electromyography, electrogoniometry, and force platform data were recorded. The majority of infants who could step under tied-belt conditions also stepped under split-belt conditions. During forward stepping at low speed differentials between the two belts (ratio, <4), infants adopted a step cycle duration that was intermediate between that expected from tied-belt stepping at each of the speeds. At large speed differentials between the two belts (ratio, 7-22), the infants took extra steps on the fast leg during the stance phase on the slow leg. When the two belts ran in opposite directions, one leg stepped forward, and the other stepped backward. During all forms of stepping, the legs maintained a reciprocal relationship, so that swing phase occurred in one leg at a time. Timing of muscle activity suggests a strong inhibition between the flexor-generating centers on each side and a weaker inhibition between the extensor-generating centers. The stepping behavior resembled that reported for other animals under similar conditions, suggesting that the pattern generator for each limb is autonomous but interacts with its counterpart for the contralateral limb.

Infant stepping: a window to the behaviour of the human pattern generator for walking.

The aim of this paper is to provide evidence, both published and new, to support the notion that human infants are particularly good subjects for the study of the pattern generator for walking. We and others have shown that stepping can be initiated by sensory input from the legs or by general heightened excitability of the infant. New results are presented here to suggest that weight support through the feet and rapid extension of the legs are important proprioceptive inputs to initiate stepping. Our previous work has shown that infants can step at many different speeds when supported on a treadmill. The step cycle duration shortens as the speed increases, with the changes coming largely from the stance phase, just as in most other terrestrial animals. Moreover, we have shown that infants will step in all directions. Regardless of the direction of stepping, the step cycle changes in the same way with walking speed, suggesting the circuitry that controls different directions of walking share common elements. We have also shown that infant stepping is highly organized. Sensory inputs, whether proprioceptive or touch, are gated in a functional way so that only important sensory inputs generate a response. For example, touch to the lateral surface of the foot elicits a response only in sideways walking, and only in the leading limb. New data is presented here to show that the pattern generators from each limb can operate somewhat independently. On a split-belt treadmill with the 2 belts running at different speeds or in different directions, the legs showed considerable independence in behaviour. Yet, the pattern generators on each side interact to ensure that swing phase does not occur at the same time. These studies have provided insight into the organization of the pattern generator for walking in humans. It will be interesting in the future to study how maturation of the descending tracts changes walking behaviour to allow independent bipedal walking.