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At least 19 recordsLinked to original sources
PubMed1988

Physical stimulation reduces the body temperature of infant rats.

Physical stimulation of rat pups, of the type normally received from the mother, has been shown to regulate several behavioral and physiological systems in the young. The present paper describes a possible role of physical stimulation in an additional physiological system; the thermoregulatory system. Within a thermoneutral environment, physical stimulation produces a decrease in rectal temperature (Expt. 1). Even in an environment of increasing temperature, similar to that pups experience when in contact with the dam, physical stimulation attenuates an increase in rectal temperature (Expt. 2). The physiological mechanism of heat loss appears to involve ventilatory heat exchange resulting in convective and evaporative heat loss (Expts. 3, 4). Furthermore, physical stimulation continues to produce a decrease in rectal temperature throughout the preweanling period (Expt. 5). These results suggest that pups may not always have to resort to behavioral thermoregulatory mechanisms which require them to separate themselves from their mother. Rather, pups may be cooled, or at least a heat gain attenuated, by physical stimulation from the dam while maintaining contact with her.

Animals↗
PubMed1994

Effect of exogenous ATP and physical stimulation on ciliary function impaired by bacterial endotoxin.

The effects of exogenous ATP and physical stimulation on ciliary beat depressed by lipopolysaccharide from Pseudomonas aeruginosa were studied in cell culture. Both the ciliary beat frequency (CBF) and the amplitude (CBA) of human respiratory cells in monolayer cell cultures were studied by using a differential interference microscope equipped with a high speed video. Both the ATP and the physiol stimulation stimulated temporarily the depressed CBF and CBA. In both groups the CBF and CBA increased in 1 min to the initial level and then gradually decreased to the level before the stimulation. The duration of the ATP stimulation on the CBF (10.1 +/- 1.8 min) and CBA (10.1 +/- 2.3 min) were significantly better than the duration of physical stimulation on CBF (8.0 +/- 1.8 min) and CBA (6.8 +/- 1.6 min). However, the areas under the CBF/CBA curves (from the beginning of stimulation until the initial level of CBF or CBA was reached again) did not differ significantly. After the removal of the bacterial toxin the CBF was restored to the initial level. In the present study the adenosine receptor antagonist could not prevent the ciliostimulative effect of exogenous ATP combined with the physical stimulation. Both exogenous ATP and physical stimulation have a clear but temporary stimulative effect on the ciliary beat depressed by bacterial toxin, ATP being slightly more effective. It seems that the effects of ATP are not mediated by adenosine receptors.

Adenosine Triphosphate↗
PubMed1986

Effect of physical stimulation on motor inhibition in children.

The effect of physical stimulation on motor inhibition and cognitive performance of 70 third-grade children was examined. 46 subjects participated in a brief, but strenuous obstacle course. Their performance on two motor inhibition tasks, a short-term memory/attentional task, and a test assessing reflectivity was assessed before the stimulation, immediately afterward, and again after a 30-min. delay. A control group (n = 24) received comparable experience without the physical intervention. Physical stimulation facilitated fine motor inhibition at both the immediate and delayed retest. The intervention interfered with an apparent practice effect on the attentional task. No condition effects were noted for gross motor performance or reflectivity, although girls were significantly more reflective at retest. It is proposed that physical stimulation augments certain aspects of inhibitory control in children.

Attention↗
PubMed1988

Physical stimulation reduces the brain temperature of infant rats.

Previous work indicated that physical stimulation, such as that which mimics the stimulation pups receive from the dam, reduces pup body temperature. The present paper reports that the body and brain temperature of 5-day-old pups covaried under steady-state thermal conditions, cold exposure, and warmth exposure (Expt. 1) suggesting that body thermoregulatory mechanisms may also regulate brain temperature. Indeed, physically stimulating pups decreased brain temperature in the neocortex (Expt. 2) and the olfactory bulb (Expt. 3). The mechanism for this brain temperature decrease appears to be an increase in ventilatory heat exchange, the same mechanism responsible for the decrease in body temperature. Pups increased respiration during stimulation, thereby increasing air flow to the lungs where convective and evaporative heat exchange occurred. Indeed, stimulating pups in a high-humidity environment blocked the decrease in brain temperature (Expt. 4). The ability of physical stimulation to decrease brain temperature appears to be limited to neonatal pups, as 10-, 15-, and 20-day-old pups did not exhibit a brain temperature decrease in response to stimulation (Expt. 5).

Animals↗
PubMed2003

Development and validation of a bioreactor for physical stimulation of engineered cartilage.

A bioreactor has been developed to apply different regimes of physical stimulation to tissue specimens under highly controlled conditions. The computer-controlled device exposes specimens to compressive deformation at various strains and frequencies, measures the load applied to each sample and allows simultaneous medium stirring at different velocities. Validation tests confirmed the accuracy of the system in (i) its displacement (errors averaged 0.072+/-0.051 microm), and in (ii) setting the contact with the samples utilizing micrometer screws coupled to plungers (errors averaged 1.74+/-0.36% for samples of 1.60-3.18 mm thickness), thus ensuring accurate compressive deformation. The developed bioreactor, which represents an advance in the technology for physical stimulation of tissue specimens, is currently used to apply compressive deformation and hydrodynamic forces to human chondrocytes cultured in biodegradable polymer scaffolds, with the goals of (i) engineering functional grafts for the repair of cartilage defects (ii).

Bioreactors↗
PubMed2000

Effects of luminal nutrient absorption, intraluminal physical stimulation, and intravenous parenteral alimentation on the recovery responses of duodenal villus morphology following feed withdrawal in chickens.

The aim of this study was to clarify which of the following three factors induces villus morphological recovery best: enteral nutrient absorption, intraluminal physical stimulation, or intravenous parenteral alimentation. At 142 d, male White Leghorn chickens (Gallus gallus domesticus) were divided into eight groups of five birds each as follows: 1) access given ad libitum to a commercial layer mash diet (CP, 17.5%; ME, 2,830 kcal/kg) (control), 2) 5-d feed withdrawal (feed withdrawal), 3) 3-d feed withdrawal (3-FW), followed by refeeding the same diet as the control for 2 d (refeeding), 4) 3-FW followed by force-feeding enteral hyperalimentation (enteral), 5) 3-FW followed by force-feeding an indigestible (nonabsorbable) substance (kaolin), 6) 3-FW followed by force-feeding water for 2 d (force-fed control), 7) 3-FW followed by parenteral hyperalimentation (parenteral), and 8) 3-FW followed by no alimentation (sham control) for 2 d. In the refeeding and enteral groups, BW significantly recovered (P < 0.05), and in the parenteral group, BW tended to increase, suggesting that nutrients were enterally and parenterally absorbed, respectively. The BW in the remaining three groups showed a significant decrease (P < 0.05), indicating that kaolin could not be absorbed enterally. Compared with the feed withdrawal group, villus height, cell mitosis, and villus tip surface morphology of refeeding and enteral groups exhibited rapid villus morphological recovery. Villus morphological recovery of the enteral group appears to have been caused by enteral nutrient absorption. However, villus morphology in the kaolin treatment was not different from that in the feed withdrawal group, which suggests that intraluminal physical stimulation had no effect on villus morphological recovery. On the other hand, the parenteral group showed no effect on villus morphological recovery, which suggests that the parenteral nutrient supplied to the villi via the blood could not induce villus morphological recovery; the intestinal mucosal atrophy might have been caused by the absence of enteral nutrients, and would only be stimulated by enteral nutrient absorption. In conclusion, the present findings suggest that villus morphology is governed neither by intraluminal physical stimulation nor by parenteral alimentation, but by enteral nutrient absorption.

Animals↗
PubMed2006

Effects of diet-deprivation and physical stimulation on the feeding behaviour of the larvae of the silkworm, Bombyx mori.

Continuous observations of larvae of the silkworm, Bombyx mori, revealed that feeding occurred at regular intervals throughout larval development. To investigate possible factors influencing meal-timing, the behaviours of diet-deprived Bombyx larvae were also analysed. Diet-deprivation resulted in longer durations of the first meals after diet replacement, but did not affect feeding patterns. Furthermore, long-term diet-deprivation promoted wandering behaviour and a consequent delay in feeding after diet replacement. Under diet-deprivation conditions, meal-starts appeared to be inducible by defecation and physical stimulation. However, stimulation-induced meal-starts were dependent on the time elapsed since the larvae's previous meals. Provided that more than 1h had elapsed since their previous meals, larvae could be induced to feed by defecation and tapping. At less than 1h post-meal, larvae were less likely to begin feeding after defecation or physical stimulation. Activated locomotions such as wandering and feeding were observed in the long-term diet-deprived larvae only after diet blocks were replaced, while long-term diet-deprived larvae did not show activated locomotion during the absence of diet blocks. Collectively, these data suggest that a combination of elevated locomotion activity and the presence of diet may be necessary for the initiation of feeding in diet-deprived larvae.

Animals↗
PubMed2003

Formation of hydroxyapatite-mediated three-dimensional structures by mouse fibroblasts in response to physical stimulation.

Hydroxyapatite (HAP) ceramics are widely used as implant materials for periodontal bone defects because of their excellent biocompatibility. We demonstrated that physical stimulation, that is, (1). mechanical stimuli or (2). laser irradiation, causes HAP-mediated C3H10T1/2 mouse fibroblasts to form three-dimensional tissue-like structures. Trypsinized 10T1/2 cells were cultured simultaneously with 200 HAP granules on a rotator for 7 days in mechanical stimulation experiments. The cells were later transferred to a regular incubator. Cell reactions were observed by phase-contrast microscopy. The formation of three-dimensional structures around the HAP granules was observed in the third week of cultivation after stimulation. In laser irradiation experiments, trypsinized cells were irradiated with 1, 5, and 16 J/cm(2) at a wavelength of 1000 nm and cultured with 200 HAP granules for 10 weeks. The formation of three-dimensional structures, like those observed in the mechanical stimulation experiments, was observed in the third week after irradiation. The formation of these structures was most frequent at 1 J/cm(2), and the frequency of formation of these structures gradually decreased as the irradiation dose was increased. These results indicate that physical stimuli may stimulate cell proliferation, leading to the repair of damaged tissue. These results also indicate that mouse fibroblasts do not form these three-dimensional structures without HAP and that HAP alone is not sufficient to stimulate the formation of three-dimensional structures.

Animals↗
PubMed1981

Effects of external physical stimulation on fetuses near term.

Measurements were made in 17 healthy pregnant women between 36 and 42 weeks' gestational age 90 minutes before and after a standard physical stimulus. The mean fetal heart rate was 138 +/- 0.4 bpm; the median value of the 5-minute standard deviation of successive heartbeat intervals was 30.3 msec, and the percentage of time spent making gross fetal body movements was 11.1% +/- 0.4%. These measurements did not change following stimulation of fetuses. Fetal breathing movements diminished over the 180-minute observation period but did not appear to be changed by fetal stimulation. During studies, periodic increases separated by periodic decreases in fetal heart rate, fetal heart rate variability, gross fetal body movements, and fetal breathing movements were measured, and these changes did not seem to be related to external stimulation of fetuses. Periodic changes in these measurements may have been related to underlying patterns of fetal behavior but were not usually influenced by external physical stimulation of fetuses.

Female↗
PubMed2004

In vitro physical stimulation of tissue-engineered and native cartilage.

Because of the limited availability of donor cartilage for resurfacing defects in articular surfaces, there is tremendous interest in the in vitro bioengineering of cartilage replacements for clinical applications. However, attaining mechanical properties in engineered cartilaginous constructs that approach those of native cartilage has not been previously achieved when constructs are cultured under free-swelling conditions. One approach toward stimulating the development of constructs that are mechanically more robust is to expose them to physical environments that are similar, in certain ways, to those encountered by native cartilage. This is a strategy motivated by observations in numerous short-term experiments that certain mechanical signals are potent stimulators of cartilage metabolism. On the other hand, excess mechanical loading can have a deleterious effect on cartilage. Culture conditions that include a physical stimulation component are made possible by the use of specialized bioreactors. This chapter addresses some of the issues involved in using bioreactors as integral components of cartilage tissue engineering and in studying the physical regulation of cartilage. We first consider the generation of cartilaginous constructs in vitro. Next we describe the rationale and design of bioreactors that can impart either mechanical deformation or fluid-induced mechanical signals.

Animals↗