Regional differences in facial skin blood flow responses to thermal stimulation.

PURPOSE: The facial skin blood flow (SkBF) shows regional differences in the responses to a given stimulation. The facial SkBFs, especially in the eyelid and nose exhibit unique response to physiological and psychological stimuli, but the mechanisms inducing those regional differences remain unclear. To investigate whether the regional differences in the local control of vasomotion in facial vessels correspond to the regional differences in facial SkBF response, we monitored the relative change of facial SkBF to regional thermal stimulation. We hypothesized that heat stimulation dilates the cutaneous vessels in the eyelid, while cold stimulation constricts those in the nose, which was based on previous findings METHODS: A thermal stimulator was used to apply temperature increase (from 20 to 40 °C at 2 °C/min) and decrease (from 40 to 20 °C at 2°C/min) in a randomized order to the right eyelid, nose, right cheek, and forehead of 14 healthy young males. The facial SkBF was measured for 10 s using laser-speckle flowgraphy when temperatures of 20 °C, 30 °C, and 40 °C had been applied for 30 s in both trials. RESULTS: The SkBF in the eyelid did not change significantly during any thermal stimulation, and the nasal SkBF did not decrease significantly during cold stimulation. The SkBFs in the cheek and forehead increased significantly with the applied temperature. CONCLUSIONS: These findings indicate that a large regional variation exists in facial skin blood flow response to local heating or cooling and that the regional variation did not correspond to the unique SkBF responses in the previous studies.

Short- and long-term effects of using a facial massage roller on facial skin blood flow and vascular reactivity.

Massage rollers are commonly used for beauty care, but their effects on skin blood flow (SkBF) and vascular reactivity remain unclear. We hypothesized that the short-term usage of a massage roller increases the SkBF, while a long-term massage intervention improves vascular dilatation. We measured the facial SkBF change to 5 min massage roller to the right cheek in 12 subjects. We also assessed the effect of 5-week daily use of facial massage roller on the SkBF in the right cheek and the reactivity to local heat in 14 subjects. The short-term massage significantly increased facial SkBF solely in the right cheek for at least 10 min after the massage. The 5-week intervention significantly increased the vasodilatation response to the heat stimulation solely in the right cheek. These findings suggested that performing short-term facial massage with a roller increases SkBF, and long-term use improves the vascular dilatation response.

Aging decreases CO2 reactivity in the retinal artery, but not in the ocular choroidal vessels; a cross-sectional study.

BACKGROUND: The CO2 reactivity is often used to assess vascular function, but it is still unclear whether this reactivity is affected by aging. OBJECTIVE: To investigate the effects of aging on the CO2 reactivity in ocular and cerebral vessels, both of which are highly sensitive to hypercapnia, we compared the CO2 reactivity in the retinal artery (RA), retinal and choroidal vessels (RCV), optic nerve head (ONH), and middle cerebral artery (MCA) between young and middle-aged subjects. METHODS: We measured the CO2 reactivity in 14 young and 11 middle-aged males using laser-speckle flowgraphy during a 3-min inhalation of CO2-rich air. RESULTS: The CO2 reactivity in the RA and ONH were lower in the middle-aged group than in the young group, but no significant effect of age was observed in the RCV or MCA. The CO2 reactivity in the RA and ONH were correlated significantly with age, whereas those in the RCV or MCA were not. CONCLUSIONS: These findings suggest that there are regional differences in the effect of age on the CO2 reactivity among not only ocular and cerebral vessels, but also the retinal and choroidal vessels, even though these vessels are in neighboring areas.

Objective and Subjective Eating Speeds Are Related to Body Composition and Shape in Female College Students.

Eating speed reportedly relates to body composition and shape. Little is known about the relationship between the objectively assessed eating speed and the body composition and shape. This study examined relationships between eating speed as assessed both objectively and subjectively, and body composition and shape. The following variables of body composition and shape were measured in 84 female college students: body mass, relative body fat mass (%Fat), body mass index (BMI), and circumferences of the waist, abdomen and hip. After measuring the body composition and shape, subjects consumed a 174-kcal salmon rice ball. The following chewing variables were measured by observing videotape recordings of the subjects' faces: number of chews per bite, total number of chews, total meal duration, number of bites, and chewing rate. The subjects were categorized into three groups (fast, moderate and slow) according to their own subjective assessments of the actual eating speed. In objective assessments of the eating speed, the total number of chews and the total meal duration were significantly negatively correlated with the body mass, %Fat, BMI, and circumferences of the waist, abdomen and hip. In subjective eating-speed assessments, the body mass, %Fat, BMI, and circumferences of the waist, abdomen and hip were greater in the fast eating group than in the slow eating group. Both the objectively and subjectively assessed eating speeds are related to the body composition and shape. The present study supports that fast eating may relate to gains in body mass and/or fat mass.

Effect of postprandial gum chewing on diet-induced thermogenesis.

OBJECTIVE: To examine the effect of postprandial gum chewing on diet-induced thermogenesis (DIT). METHODS: Twelve healthy normal-weight males completed four trials on four different days. They chewed a 621-kcal test meal for as long as possible and as many times as possible in the slow-eating trials, while they consumed the same meal as rapidly as possible in the rapid-eating trials. In the gum-chewing trials, they chewed a 3-kcal gum for 15 min after the meal. In the non-gum-chewing trials, they consumed 3 kcal of sugar with the test meal instead of chewing the gum. DIT was calculated based on the oxygen uptake, body mass, and postprandial increments in energy expenditure above the baseline as measured before each trial. RESULTS: DIT was significantly greater in the gum-chewing trials than in the non-gum-chewing trials for both rapid-eating and slow-eating trials. The difference in DIT between rapid-eating and slow-eating trials was greater than that between non-gum-chewing and gum-chewing trials. CONCLUSIONS: Postprandial gum chewing enhanced DIT, but the effect of gum chewing on DIT did not exceed that of slow eating when consuming a meal.

Inner ocular blood flow responses to an acute decrease in blood pressure in resting humans.

Whether inner ocular vessels have an autoregulatory response to acute fluctuations in blood pressure is unclear. We tried to examine the validity of acute hypotension elicited by thigh-cuff release as to assess the dynamic autoregulation in the ocular circulation. Blood flow velocity in the superior nasal and inferior temporal retinal arterioles, and in the retinal and choroidal vasculature were measured with the aid of laser speckle flowgraphy before and immediately after an acute decrease in blood pressure in 20 healthy subjects. Acute hypotension was induced by a rapid release of bilateral thigh occlusion cuffs that had been inflated to 220 mmHg for 2 min. The ratio of the relative change in retinal and choroidal blood flow velocity to the relative change in mean arterial blood pressure (MAP) was calculated. Immediately after cuff release, the MAP and blood flows in the all ocular target vessels decreased significantly from the baseline values obtained before thigh-cuff release. The ratio of the relative change in inner ocular blood flow velocity to that in the MAP exceeded 1% / %mmHg. An explicit dynamic autoregulation in inner ocular vessels cannot be demonstrated in response to an acute hypotension induced by the thigh-cuff release technique.

Ocular blood flow decreases during passive heat stress in resting humans.

BACKGROUND: Heat stress induces various physiological changes and so could influence ocular circulation. This study examined the effect of heat stress on ocular blood flow. FINDINGS: Ocular blood flow, end-tidal carbon dioxide (P(ET)CO2) and blood pressure were measured for 12 healthy subjects wearing water-perfused tube-lined suits under two conditions of water circulation: (1) at 35 °C (normothermia) for 30 min and (2) at 50 °C for 90 min (passive heat stress). The blood-flow velocities in the superior temporal retinal arteriole (STRA), superior nasal retinal arteriole (SNRA), and the retinal and choroidal vessels (RCV) were measured using laser-speckle flowgraphy. Blood flow in the STRA and SNRA was calculated from the integral of a cross-sectional map of blood velocity. PETCO2 was clamped at the normothermia level by adding 5% CO2 to the inspired gas. Passive heat stress had no effect on the subjects' blood pressures. The blood-flow velocity in the RCV was significantly lower after 30, 60 and 90 min of passive heat stress than the normothermic level, with a peak decrease of 18 ± 3% (mean ± SE) at 90 min. Blood flow in the STRA and SNRA decreased significantly after 90 min of passive heat stress conditions, with peak decreases of 14 ± 3% and 14 ± 4%, respectively. CONCLUSION: The findings of this study suggest that passive heat stress decreases ocular blood flow irrespective of the blood pressure or arterial partial pressure of CO2.