Plasminogen activating inhibitor-1 promotes angiogenesis in cutaneous angiosarcomas.

Plasminogen activating inhibitor-1 (PAI-1) is associated with poor clinical outcomes, and elevated levels of PAI-1 in both tissue and serum are correlated with poor response to therapy in various cancers, including skin cancer. Cutaneous angiosarcoma (CAS) is a vascular tumor histologically characterized by detachment of endothelial cell-derived tumor cells. Since CAS expresses multiple angiogenic growth factors and has increased expressions of angiogenic receptor tyrosine kinase transcripts including VEGFR1/2/3, angiogenesis-promoting factors are potential drug targets in CAS. In this study, the expression of PAI-1 was examined in 31 cases of CAS, and the immunomodulatory effects of PAI-1 on a human CAS cell line, ISO-HAS-B, were evaluated. We found that, of the angiogenesis-promoting factors, PAI-1 was expressed in almost all cases of CAS, and PAI-1 increased the mRNA expressions of IL-23p19, VEGF-C, CXCL5 and CCL20 on ISO-HAS-B. Moreover, PAI-1 stimulated ISO-HAS-B culture supernatant promoted favourable tube networks, suggesting that these tumor-derived factors promote the pro-angiogenic effect on tumor development. In addition, IL-23p19 was expressed in 61.3% of cases, whereas VEGF-C was expressed in 41% of cases. The results of the present study suggest that PAI-1 promotes angiogenesis that results in tumor progression in CAS.

Relationship Between Cerebral Oxygenation and Skin Blood Flow at the Frontal Lobe during Progressive Hypoxia: Impact of Acute Hypotension.

We investigated the relationship between cerebral oxygenation (COX) and skin blood flow (SkBF) at the left frontal lobes of 10 healthy young men during progressive hypoxia (∼ -1 h at each of 21%, 18%, 15%, and 12% of inspired oxygen [FiO2]). Acute hypotension was manipulated by a thigh-cuff-release technique, where a pressure of 220 mmHg was applied at both thigh muscles for 3 min and the cuff was immediately released to induce acute hypotension. While the resting baseline for COX before the thigh-cuff release manipulation decreased gradually with the reduction of FiO2 (P < 0.05), the resting baseline for SkBF, mean arterial blood pressure (MAP), and cutaneous vascular conductance (CVC) were unaffected by FiO2 (P > 0.05). The acute hypotension that was induced by the thigh-cuff release decreased COX, SkBF, MAP, and CVC; thereafter, these values recovered toward their baseline values. During the hypotension phase, while the time to the nadir values for COX slowed progressively with reductions in FiO2 (P < 0.05), those for SkBF, MAP, and CVC were unaffected by FiO2 (P > 0.05). These results suggest that COX may not be associated with SkBF for the protocol or with the subjects in the present study.

Barometric pressure change and heart rate response during sleeping at ~ 3000 m altitude.

We investigated effects of change in barometric pressure (P B) with climate change on heart rate (HR) during sleep at 3000 m altitude. Nineteen healthy adults (15 males and four females; mean age 32 years) participated in this study. We measured P B (barometry) and HR (electrocardiography) every minute during their overnight stay in a mountain lodge at ~ 3000 m. We also measured resting arterial oxygen saturation (SpO2) and evaluated symptoms of acute mountain sickness (AMS) by using the Lake Louise Questionnaire at 2305 and 3000 m, respectively. P B gradually decreased during the night at the speed of approximately - 0.5 hPa/h. We found that HR during sleep decreased linearly as P B decreased in all subjects, with significance (r = 0.492-0.893; all, P < 0.001). Moreover, cross correlation analysis revealed that HR started to decrease after ~ 15 min following the decrease in P B, on average. SpO2 was 93.8 ± 1.7% at 2305 m before climbing, then decreased significantly to 90.2 ± 2.2% at the lodge before going to bed, and further decreased to 87.5 ± 2.7% after waking (all, P < 0.05). Four of the 19 subjects showed a symptom of AMS after waking (21%). Further, the decrease in HR in response to a given decrease in P B (ΔHR/ΔPB) was negatively related with a decrease in SpO2 from before going to bed to after waking at 3000 m (r = - 0.579, P = 0.009) and with total AMS scores after waking (r = 0.489, P = 0.033).

Jump training with blood flow restriction has no effect on jump performance.

This study investigated whether jump training with blood flow restriction (BFR) improves jump performance compared to jump training without BFR under similar exercise intensity in healthy young humans. The participants were twenty healthy males who were assigned to either jump training with BFR (n = 10) or jump training without BFR [control (CON); n = 10] groups. All subjects completed five sets of 10 repetitions with one-minute intervals of half-squat jumps (SJ) at maximal effort, four days a week for four weeks. In the BFR group, circulatory occlusion around both thigh muscles was applied at a pressure of 200 mmHg, and physical characteristics, muscle strength and jump performance were evaluated before and after training. A significant main effect of training period on lean body mass, percentage of body fat and leg circumference in both groups was observed (P < 0.05). For jump training with BFR, only knee flexion strength increased (P < 0.05), while in the CON group, both knee extension and flexion strength increased (P < 0.05). BFR training did not improve SJ or counter-movement jumps (CMJ) (P > 0.05), whereas training without BFR (CON) improved the performance of both jumps (SJ: pre 35.7 ± 5.1 vs. post 38.9 ± 4.1 cm, P = 0.002: CMJ: pre 41.6 ± 3.6 vs. post 44.6 ± 3.8 cm, P < 0.001). These results indicate that jump training with BFR may not be an effective strategy for improving jump performance.

Effect of progressive normobaric hypoxia on dynamic cerebral autoregulation.

NEW FINDINGS: What is the central question of this study? Acute hypoxia reduces dynamic cerebral autoregulation (dCA); however, it is unclear what level of hypoxia is necessary to exert this effect. We sought to investigate whether dCA would be reduced during progressive periods of normobaric hypoxia using a duplex Doppler ultrasound technique to evaluate the volumetric blood flow. What is the main finding and its importance? We showed that dCA decreased linearly as inspired O2 decreased from 21 to 12%. Additionally, symptoms of acute mountain sickness were related to changes in dCA. Our results may provide a sensitive and clinically relevant test to evaluate the risk of acute mountain sickness. Cerebral blood flow is maintained at relatively constant levels over a wide range of perfusion pressures via cerebral autoregulation (CA). Although acute hypoxia reduces dynamic CA, it is unclear what level of hypoxia is necessary to exert this effect. We evaluated dynamic CA during progressive normobaric hypoxia (∼1 h at each of 21, 18, 15 and 12% O2 ) using duplex ultrasonography to measure volumetric changes in common carotid artery blood flow of 11 healthy young men. Dynamic CA was evaluated by the thigh-cuff method and represented as the rate of regulation of vascular conductance. On a separate occasion, symptoms of acute mountain sickness were evaluated during 6 h of prolonged hypoxia (fractional inspired O2 of 14.1%) using the Lake Louise Questionnaire. Repeated-measures ANOVA with linear trend analysis indicated that dynamic CA decreased progressively as fractional inspired O2 was reduced (P < 0.001). Spearman rank order analysis revealed that symptoms of acute mountain sickness were related to changes in the rate of regulation of vascular conductance from 21 to 15% (r = -0.869, P = 0.006) and from 21 to 12% O2 (r = -0.648, P = 0.040), respectively. These results suggest that dynamic CA worsens with progressive hypoxia and that reductions in dynamic CA during moderate to severe hypoxia (<15% O2 ) may be related to the severity of acute mountain sickness.

Reduction in Cerebral Oxygenation After Prolonged Exercise in Hypoxia is Related to Changes in Blood Pressure.

We investigated the relation between blood pressure and cerebral oxygenation (COX) immediately after exercise in ten healthy males. Subjects completed an exercise and recovery protocol while breathing either 21% (normoxia) or 14.1% (hypoxia) O2 in a randomized order. Each exercise session included four sets of cycling (30 min/set, 15 min rest) at 50% of altitude-adjusted peak oxygen uptake, followed by 60 min of recovery. After exercise, mean arterial pressure (MAP; 87±1 vs. 84±1 mmHg, average values across the recovery period) and COX (68±1% vs. 58±1%) were lower in hypoxia compared to normoxia (P<0.001). Changes in MAP and COX were correlated during the recovery period in hypoxia (r=0.568, P<0.001) but not during normoxia (r=0.028, not significant). These results demonstrate that reductions in blood pressure following exercise in hypoxia are (1) more pronounced than in normoxia, and (2) associated with reductions in COX. Together, these results suggest an impairment in cerebral autoregulation as COX followed changes in MAP more passively in hypoxia than in normoxia. These findings could help explain the increased risk for postexercise syncope at high altitude.

Comparisons of energy cost and economical walking speed at various gradients in healthy, active younger and older adults.

BACKGROUND/OBJECTIVE: Oxygen consumption during walking per unit distance (Cw ; mL/kg/m) is known to be greater for older adults than younger adults, although its underlying process is controversial. METHODS: We measured the Cw values at six gait speeds from 30 m/min to 105 m/min on level ground and gradient slopes (±5%) in healthy younger and older male adults. A quadratic approximation was applied for a relationship between Cw and gait speeds (v; m/min). It gives a U-shaped Cw -v relationship, which includes a particular gait speed minimizing the Cw , the so-called economical speed (ES). The age-related difference of the Cw -v relationship was assessed by comparisons of ES and/or Cw . RESULTS: A significantly greater Cw at 30 m/min and slower ES were found for older adults at the downhill gradient, suggesting that a combination of leftward and upward shifts of the Cw -v relationship was found at that gradient. Only a slower ES was found for older adults at the uphill gradient, suggesting that a leftward shift was found for older adults at that gradient. Neither a significant leftward nor an upward shift was found at the level gradient. Leg length significantly correlated to the ES for younger adults at the level and downhill gradients, while such a significant relationship was observed only at the level gradient for older adults. The maximal quadriceps muscle strength significantly correlated to the ES for older adults at all gradients, but not for younger adults. CONCLUSION: The age-related alteration of the Cw -v relationship depends on the gradient, and its related factors were different between age groups.

An effective strategy to reduce blood pressure after forest walking in middle-aged and aged people.

[Purpose] Forest walking may be effective for human health, but little information is available about effects of energy expenditure on blood pressure responses after forest walking. The aim of this study was to investigate the relationship between the activity energy expenditure and changes in blood pressure in individuals after forest walking. [Subjects] The subjects were 54 middle-aged and elderly people. [Methods] All subjects walked in the forest for approximately 90 min. Blood pressure, salivary amylase, and the Profile of Mood States were evaluated before and after forest walking, and activity energy expenditure was monitored throughout forest walking. Subjects were divided into two groups according to mean arterial pressure changes: a responder group (>5% decreases) and a nonresponder group (<5%). [Results] Forest walking significantly reduced the mean arterial pressure and improved the Profile of Mood States in both groups. Activity energy expenditure was related to changes in mean arterial pressure in the responder group, while this relation was not observed in the nonresponder group. Differential activity energy expenditure did not strongly affect improvement of the Profile of Mood States. [Conclusion] Greater walking-related greater activity energy expenditure might be required to accentuate physiological beneficial effects on in middle-aged and aged people. Furthermore, the forest environment per se can attenuate psychological stress.

CD25 expression could be a prognostic marker of bexarotene monotherapy for cutaneous T-cell lymphomas.

Bexarotene is often administered to phototherapy-resistant early cutaneous T-cell lymphoma (CTCL) patients as one of the first-line therapies in real-world practice. Since bexarotene reduces the expression of CCR4 in CTCL cells and CCL22 to decrease serum CCL22 levels, bexarotene inhibits the migration of CTCL cells, as well as other CCR4+ cells, such as cytotoxic T cells and regulatory T cells, in the lesional skin of CTCL. In this report, the efficacy of bexarotene in 28 cases of CTCL, as well as its correlations with immunohistochemical profiles of tumour-infiltrating leucocytes (TILs), was retrospectively investigated. The overall response rate at 1 and 4 months for the total cohort was 70.8% (95% CI, 50.6%-86.3%) and 47.8% (95% CI, 29.2%-67.0%), respectively. The disease control rate for the total cohort at 4 months was 65.2% (95% CI, 44.8%-81.3%). The mean event-free survival for all patients was 4.1 months (0.3-68.5 months). In addition, the immunoreactive cells were calculated using digital microscopy, suggesting that the ratio of CD25+ cells among TILs was significantly increased in patients who responded to bexarotene (p = 0.0209), whereas there were no significant differences in the ratios of CD8+ cells, granulysin+ cells, and Foxp3+ cells among TILs between responder and non-responder patients. Collectively, the ratio of CD25 expression among TILs might be a predictive biomarker for the efficacy of bexarotene.

LL-37 Might Promote Local Invasion of Melanoma by Activating Melanoma Cells and Tumor-Associated Macrophages.

LL-37 can stimulate various skin-resident cells to contribute to tumor development. Since tumor (T) stage is determined by the vertical invasion of tumor cells in melanoma, we hypothesized that the LL-37 expression level is correlated with the T stage in melanoma patients. Immunohistochemical staining of LL-37 was performed in each stage of melanoma (Tis-T4), suggesting the ratio of LL-37-expressing cells correlate positively to T stage severity. Next, to examine pro-angiogenetic factors induced by LL-37 stimulation, the B16F10 melanoma model was used. Intra-tumorally administered CRAMP, the mouse ortologe of LL-37, significantly increased the mRNA expression of CXCL5, IL23A, MMP1a, and MMP9 in B16F10 melanoma. To confirm the induction of pro-angiogenic factors, A375 human melanoma cells were stimulated by LL-37 in vitro. The mRNA expression of CXCL5, IL23A, and MMP9, but not MMP1, were significantly increased by LL-37 stimulation. Moreover, LL-37-stimulated A375 culture supernatant promoted tube networks, suggesting that these tumor-derived factors promote the pro-angiogenic effect on tumor development. In contrast to melanoma cell lines, M2 macrophages stimulated by LL-37 in vitro significantly increased their expression and secretion of MMP-1, but not MMP-9 expression. Collectively, these results suggest that LL-37 stimulates both tumor cells and macrophages to promote melanoma invasion by the induction of pro-angiogenic factors.

Impact of Dietary Nitrate Supplementation on Executive Function During Hypoxic Exercise.

We investigated the effects of 4-day dietary beetroot (BR) juice supplementation on executive function assessed by color-word Stroop task (CWST) in hypoxia (fraction of inspired oxygen [FiO2] = 0.1395). Eight healthy young men performed 25-minute leg cycling exercise (target heart rate, 140 bpm) randomly with placebo (PL) juice or BR supplementation. The CWST was evaluated at resting hypoxic condition (after 30 minutes of hypoxic exposure) and at 15 minutes during exercise. During exercise, the correct response time in the CWST was significantly shortened compared with those at rest with no differences between PL and BR. The response accuracy in the CWST with BR was marginally lower than that with PL during exercise (p = 0.066). There were no significant differences in all physiological values, including pulmonary ventilation, arterial oxygen saturation, partial pressure of end-tidal carbon dioxide output, and tissue oxygenation in the left frontal lobe, assessed by near-infrared spectroscopy during exercise conditions involving PL and BR supplementation. These results suggest that moderate exercise in hypoxia partially improved executive function; however, 4-day dietary BR supplementation did not improve executive function during hypoxic exercise.

Impact of Sleeping Altitude on Symptoms of Acute Mountain Sickness on Mt. Fuji.

Horiuchi, Masahiro, Tadashi Uno, Junko Endo, Yoko Handa, and Tatsuya Hasegawa. Impact of sleeping altitude on symptoms of acute mountain sickness on Mt. Fuji. High Alt Med Biol. 19:193-200, 2018. AIMS: We sought to investigate the factors influencing acute mountain sickness (AMS) on Mt. Fuji in Japan, in particular, to assess the effects of sleeping altitude, by means of a questionnaire survey. This study involved 1932 participants who climbed Mt. Fuji, and obtained information regarding sex, age, and whether participants stayed at the mountain lodges. The AMS survey excluded the perceived sleep difficulties assessed with the Lake Louise Scoring (LLS) system for all climbers. RESULTS: The overall prevalence of AMS was 31.6% for all participants (LLS score ≥3 with headache, excluding sleep difficulties). A univariate analysis revealed that overnight stay at Mt. Fuji was associated with an increased prevalence of AMS, but that sex and age were not. For overnight lodgers, the mean sleeping altitude in participants with AMS was slightly higher than that in participants without AMS (p < 0.05). Moreover, participants who stayed above 2870 m were more likely to experience AMS than those who stayed below 2815 m (p < 0.001), but sex and age were not significantly associated with the probability of experiencing AMS. CONCLUSIONS: Staying overnight at a mountain lodge, especially one above 2870 m, may be associated with an increased prevalence of AMS on Mt. Fuji.

The inhibitory effect of the components of Cornus officinalis on melanogenesis.

Five known compounds were isolated from a Cornus officinalis 50% ethanol extract (C. officinalis extract) and a hot water extract. We investigated the photochemical and pharmacological active compounds of C. officinalis hot water extract and ethanol extract. We understood that C. officinalis is a medicinal plant with potent free-radical-scavenging activity not only against reactive oxygen species (H(2)O(2), superoxiside anion, hydroxyl radical, etc.) in a narrow sense, but also against many other free radicals (peroxynitrate, peroxyradical). It is estimated that the reduction effect with C. officinalis extract can block oxidative reaction on melanogenesis. Loganin and cornuside, the components in C. officinalis, showed a significant free-radical-scavenging activity and inhibitory effects on melanogenesis. We report to prove the inhibitory effect of UVB-induced pigmentation in C. officinalis extract through its radical scavenging activity.

Impact of Carbohydrate-Electrolyte Beverage Ingestion on Heart Rate Response While Climbing Mountain Fuji at ~3000 m.

We sought to investigate whether carbohydrate-electrolyte beverage ingestion reduced heart rate (HR) in twenty-three healthy young adults while climbing Mount Fuji at a given exercise intensity. Twenty-three healthy adults were randomly divided into two groups: the tap water (11 males [M] and 1 female [F]) and the carbohydrate-electrolyte group (10 M and 1 F). HR and activity energy expenditure (AEE) were recorded every min. The HRs for the first 30 minutes of climbing were not significantly different between the groups [121 ± 2 beats per min (bpm) in the tap water and 116 ± 3 bpm in the carbohydrate-electrolyte]; however, HR significantly increased with climbing in the tap water group (129 ± 2 bpm) but showed no significant increase in the carbohydrate-electrolyte group (121 ± 3 bpm). In addition, body weight changes throughout two days ascending and descending on Mount Fuji were inversely related to changes in resting HR. Further, individual variation of body weight changes was suppressed by carbohydrate-electrolyte drink. Collectively, carbohydrate-electrolyte beverage intake may attenuate an increase in HR at a given AEE while mountaineering at ~3000 m compared with tap water intake.

Muscle oxygenation profiles between active and inactive muscles with nitrate supplementation under hypoxic exercise.

Whether dietary nitrate supplementation improves exercise performance or not is still controversial. While redistribution of sufficient oxygen from inactive to active muscles is essential for optimal exercise performance, no study investigated the effects of nitrate supplementation on muscle oxygenation profiles between active and inactive muscles. Nine healthy males performed 25 min of submaximal (heart rate ~140 bpm; EXsub) and incremental cycling (EXmax) until exhaustion under three conditions: (A) normoxia without drink; (B) hypoxia (FiO2 = 13.95%) with placebo (PL); and (c) hypoxia with beetroot juice (BR). PL and BR were provided for 4 days. Oxygenated and deoxygenated hemoglobin (HbO2 and HHb) were measured in vastus lateralis (active) and biceps brachii (inactive) muscles, and the oxygen saturation of skeletal muscle (StO2; HbO2/total Hb) were calculated. During EXsub, BR suppressed the HHb increases in active muscles during the last 5 min of exercise. During EXmax, time to exhaustion with BR (513 ± 24 sec) was significantly longer than with PL (490 ± 39 sec, P < 0.05). In active muscles, BR suppressed the HHb increases at moderate work rates during EXmax compared to PL (P < 0.05). In addition, BR supplementation was associated with greater reductions in HbO2 and StO2 at higher work rates in inactive muscles during EXmax Collectively, these findings indicate that short-term dietary nitrate supplementation improved hypoxic exercise tolerance, perhaps, due to suppressed increases in HHb in active muscles at moderate work rates. Moreover, nitrate supplementation caused greater reductions in oxygenation in inactive muscle at higher work rates during hypoxic exercise.

Effects of Short-Term Acclimatization at the Summit of Mt. Fuji (3776 m) on Sleep Efficacy, Cardiovascular Responses, and Ventilatory Responses.

Horiuchi, Masahiro, Shiro Oda, Tadashi Uno, Junko Endo, Yoko Handa, and Yoshiyuki Fukuoka. Effects of short-term acclimatization at the summit of Mt. Fuji (3776 m) on sleep efficacy, cardiovascular responses, and ventilatory responses. High Alt Med Biol. 18:171-178, 2017.-We investigated the effects of a short period of acclimatization, at 3776 m on Mt. Fuji, on sleep parameters and related physiological responses. Physiological responses were assessed in seven healthy lowlander men during both daytime and sleep while at sea level (SL), as well as for three consecutive nights at high altitude (HA; 3776 m, day 1 [D1], D2, D3, and morning only of D4). Blood pressure variables, heart rate (HR), pulmonary ventilation (VE), and breathing frequency (Bf) progressively increased each day, with significant differences between SL and HA (p < 0.05, respectively). In contrast, end-tidal PCO2 (PETCO2) progressively decreased each day with statistical differences between SL and D3 at HA (p < 0.05). During sleep at HA, mean arterial pressure (MAP) was stable, whereas it decreased during sleep at SL. Sleep efficacy, which was assessed by actigraphy, was linearly impaired with statistical differences between SL and D3 (p < 0.05). These impairments in sleep efficacy at HA were associated with higher MAP and HR, as well as lower Bf and PETCO2 during the daytime (pooled data, p < 0.05, respectively). These results suggest that hypoxia-induced cardiovascular and ventilatory responses may be crucial contributors to changes in sleep efficacy at HA.

Prevalence of acute mountain sickness on Mount Fuji: A pilot study.

BACKGROUND: Few studies have investigated climbing-related acute mountain sickness (AMS) on Mt Fuji. Although several studies of AMS have been conducted elsewhere, Mt Fuji is unique because there are many mountain lodges between the fifth station (a common starting point for climbers at an altitude of 2305 m) and the summit (3776 m), and many climbers commonly sleep overnight at mountain lodges during their ascents. This study surveyed the prevalence of AMS among climbers on Mt Fuji to determine which factors, if any, were related to the risk of developing AMS. METHODS: This study collected data from 345 participants who climbed Mt Fuji in August 2013, including information regarding age, sex, climbing experience and whether the climber stayed at a mountain lodge (n = 239). AMS was surveyed using the Lake Louise Score (LLS) questionnaire. The item on perceived sleep quality was excluded for those who did not stay at a mountain lodge (n = 106). RESULTS: The overall prevalence of AMS was 29.5% (≥ 3 LLS with headache). According to a univariate analysis, AMS was not associated with sex (male vs female), age group (20-29, 30-39, 40-49 or >50 years) or stay at a mountain lodge (single day vs overnight stay). Conversely, prior experience climbing Mt Fuji (no prior attempts vs one or more prior attempts) was related to the risk of AMS. In addition, there was a significant deviation in the number of participants reporting poor sleep, and total sleep time was significantly shorter in participants with AMS. CONCLUSIONS: These preliminary findings suggest that no single factor can explain the risk for developing AMS while climbing Mt Fuji. In addition, impaired perceived sleep quality was associated with the severity of AMS in climbers who stayed overnight at a mountain lodge.

Cognitive Function and Cerebral Oxygenation During Prolonged Exercise Under Hypoxia in Healthy Young Males.

Dobashi, Shohei, Masahiro Horiuchi, Junko Endo, Masataka Kiuchi, and Katsuhiro Koyama. Cognitive function and cerebral oxygenation during prolonged exercise under hypoxia in healthy young males. High Alt Med Biol. 17:214-221, 2016.-The present study examined the effect of prolonged hypoxic exercise on cognitive function. Eight healthy male volunteers were required to complete exercise trials (four 30-minute cycling sessions with a 15-minute rest interval) at an intensity corresponding to 50% of their altitude-adjusted peak oxygen uptake under two different conditions: normoxia (room air at 400 m) and hypoxia (fraction of inspired oxygen: 0.141). Cognitive function was evaluated before, during, and 60 minutes after completion of the exercise trial. The color-word Stroop task (CWST) was used to assess cognitive function, with regard to the number of achievements, accuracy rate, and the number of correct responses made within 60 seconds. Cerebral oxygenation was monitored throughout the experimental period using near-infrared spectroscopy. The accuracy rate did not significantly differ between the two trials. A significant reduction in the number of correct responses during simple CWST tasks was detected in the hypoxic condition 60 minutes after exercise (p < 0.05), wherein a significant correlation was identified between reduced task performance on simple CWST and cerebral oxygenation (p < 0.01). These results demonstrate that prolonged exercise under hypoxic conditions induces a reduction in cerebral oxygenation partly associated with impairment of cognitive function.

Impact of ischemic preconditioning on functional sympatholysis during handgrip exercise in humans.

Repeated bouts of ischemia followed by reperfusion, known as ischemic preconditioning (IPC), is found to improve exercise performance. As redistribution of blood from the inactive areas to active skeletal muscles during exercise (i.e., functional sympatholysis) is important for exercise performance, we examined the hypothesis that IPC improves functional sympatholysis in healthy, young humans. In a randomized study, 15 healthy young men performed a 10-min resting period, dynamic handgrip exercise at 10% maximal voluntary contraction (MVC), and 25% MVC. This protocol was preceded by IPC (IPC; 4 × 5-min 220-mmHg unilateral occlusion) or a sham intervention (CON; 4 × 5-min 20-mmHg unilateral occlusion). Near-infrared spectroscopy was used to assess changes in oxygenated hemoglobin and myoglobin in skeletal muscle (HbO2 + MbO2) in response to sympathetic activation (via cold pressor test (CPT)) at baseline and during handgrip exercise (at 10% and 25%). In resting conditions, HbO2 + MbO2 significantly decreased during CPT (-11.0 ± 1.0%), which was significantly larger during the IPC-trial (-13.8 ± 1.2%, P = 0.006). During handgrip exercise at 10% MVC, changes in HbO2 + MbO2 in response to the CPT were blunted after IPC (-8.8 ± 1.5%) and CON (-8.3 ± 0.4%, P = 0.593). During handgrip exercise at 25% MVC, HbO2 + MbO2 in response to the CPT increased (2.0 ± 0.4%), whereas this response was significantly larger when preceded by IPC (4.2 ± 0.6%, P = 0.027). Collectively, these results indicate that IPC-induced different vascular changes at rest and during moderate exercise in response to sympathetic activation. This suggests that, in healthy volunteers, exposure to IPC may alter tissue oxygenation during sympathetic stimulation at rest and during exercise.

Sweet taste threshold for sucrose inversely correlates with depression symptoms in female college students in the luteal phase.

Influences of depression symptoms on the sweet taste threshold were investigated in healthy college students (30 males and 40 females). Depression symptoms were scored by SDS (Self-Rating Depression Scale), and anxiety levels by STAI (State- and Trait-Anxiety Inventory). Recognition thresholds for sucrose were determined. In female students, the menstrual phase on the day of the experiment was self-reported. Depression symptoms, anxiety levels, and the recognition threshold for sucrose were not different among the 3 groups, i.e. males, females in the follicular phase, and females in the luteal phase. Depression symptoms were positively correlated with state and trait anxiety in all groups. The sweet taste threshold was inversely correlated with depression symptoms (r=-0.472, p=0.031) and trait anxiety (r=-0.506, p=0.019) in females in the luteal phase. In males as well as females in the follicular phase, however, no correlation between sweet taste threshold and depression was found. The results show that the recognition threshold for sucrose reduces with increased depression in females with a higher anxiety trait, but only in the luteal phase. It is hypothesized that brain regions, which spatially overlap and are responsible for both aversive emotions and gustatory processing, are susceptible to periodic changes in gonadal hormones due to the menstrual cycle.