Effects of repeated carbon dioxide-rich water bathing on core temperature, cutaneous blood flow and thermal sensation

Precooling via immersion in CO2-enriched water at 25°C decreased core body temperature but did not improve 10-km cycling time trial in the heat

This study compared the effects of precooling via whole-body immersion in 25°C CO2-enriched water (CO2WI), 25°C unenriched water (WI) or no cooling (CON) on 10-km cycling time trial (TT) performance. After 30 min of precooling (CO2WI, CON, WI) in a randomized, crossover manner, 11 male cyclists/triathletes completed 30-min submaximal cycling (65%VO2peak), followed by 10-km TT in the heat (35°C, 65% relative humidity). Average power output and performance time during TT were similar between conditions (p = 0.387 to 0.833). Decreases in core temperature (Tcore) were greater in CO2WI (-0.54 ± 0.25°C) than in CON (-0.32 ± 0.09°C) and WI (-0.29 ± 0.20°C, p = 0.011 to 0.022). Lower Tcore in CO2WI versus CON was observed at 15th min of exercise (p = 0.050). Skin temperature was lower in CO2WI and WI than in CON during the exercise (p < 0.001 to 0.031). Only CO2WI (1029 ± 305 mL) decreased whole-body sweat loss compared with CON (1304 ± 246 mL, p = 0.029). Muscle oxygenation by near-infrared spectroscopy (NIRS), thermal sensation, and thermal comfort were lower in CO2WI and WI versus CON only during precooling (p < 0.001 to 0.041). NIRS-derived blood volume was significantly lower in CO2WI and WI versus CON during exercise (p < 0.001 to 0.022). Heart rate (p = 0.998) and rating of perceived exertion (p = 0.924) did not differ between conditions throughout the experiment. These results suggested that CO2WI maybe more effective than WI for enhanced core body cooling and minimized sweat losses.

Modification of Peripheral Blood Flow and Angiogenesis by CO2 Water-Bath Therapy in Diabetic Skeletal Muscle with or without Ischemia

Previously, it was shown that both blood flow and angiogenesis in the ischemic hind limb of diabetic rats were increased upon CO2 treatment for 4 weeks. In the present study, we have compared the effects of 6 weeks CO2 therapy in diabetic rats with or without peripheral ischemia. Diabetes was induced in rats by a tail vein injection of streptozotocin (65 mg/kg body weight), whereas peripheral ischemia was produced by occluding the femoral artery at 2 weeks of inducing diabetes. Both diabetic and diabetic-ischemic animals were treated with or without CO2 water-bath at 37 °C for 6 weeks (30 min/day; 5 days/week) starting at 2 weeks, after the induction of ischemia. CO2 treatment did not affect heart rate and R-R interval as well as plasma levels of creatine kinase, glucose, cholesterol, triglycerides and high density lipoproteins. Unlike the levels of plasma Ox-LDL, MDA and TNF-α, the levels of NO in diabetic group were increased by CO2 water-bath treatment. On the other hand, the levels of plasma Ox-LDL and MDA were decreased whereas that of NO was increased without any changes in TNF-α level in diabetic-ischemic animals upon CO2 therapy. Treatment of diabetic animals with CO2 increased peak, mean and minimal blood flow by 20, 49 and 43% whereas these values were increased by 53, 26 and 80% in the diabetic-ischemic group by CO2 therapy, respectively. Blood vessel count in diabetic and diabetic-ischemic skeletal muscles was increased by 73 and 136% by CO2 therapy, respectively. These data indicate that peripheral ischemia augmented the increase in blood flow and development of angiogenesis in diabetic skeletal muscle upon CO2 therapy. It is suggested that greater beneficial effects of CO2 therapy in diabetic-ischemic animals in comparison to diabetic group may be a consequence of difference of changes in the redox-sensitive signal transduction mechanisms.

Carbon dioxide-induced decrease in extracellular pH enhances the production of extracellular matrix components by upregulating TGF-β1 expression via CREB activation in human dermal fibroblasts

Mild acidification caused by transcutaneous administration of carbon dioxide (CO2 ) has been reported to improve some epidermal skin impairments, such as desquamation and inflammation; however, its effects on dermal tissue remain unclear. Here, we examined the effect and mechanism of mild acidity on extracellular matrix (ECM) protein production in normal human dermal fibroblasts (NHDFs). To achieve this, the skin permeability of CO2 and its effect on intradermal pH were evaluated by treating reconstructed human skin equivalents (HSEs) with a CO2 -containing formulation. Additionally, NHDFs were cultured in a pH-adjusted medium (pH 6.5). CO2 successfully permeated HSEs and reduced the intradermal pH. Decreased extracellular pH activated CREB, upregulated TGF-β1 expression, promoted the production of elastic and collagen fibres, and increased hyaluronan concentration in NHDFs. Additionally, the low pH-induced increase in TGF-β1 expression was attenuated via the RNAi-mediated suppression of the expression of CREB1 and proton-sensing G protein-coupled receptors (GPCRs), including GPR4 and GPR65. Moreover, low pH-induced CREB activation was suppressed by the inhibition of the cAMP/PKA and PLC/PKC signalling pathways. Taken together, a CO2 -induced decrease in intradermal pH may promote ECM production in NHDFs via the upregulation of TGF-β1 expression, which was mediated by the activation of the GPCR signalling pathway and CREB, indicating that CO2 could be used to treat ultraviolet radiation-induced photoaging, intrinsic ageing and ECM deterioration.

Effect of hydrotherapy, balneotherapy, and spa therapy on blood pressure: a mini-review

Hypertension (high blood pressure) is one of the most common health conditions. When your blood pressure is high for a long term, it can cause health problems, such as heart disease. In addition to the main methods of treatment, there are various methods of adjuvant therapy, one of the most common of which is hydrotherapy. In this review study, we examined the effects of hydrotherapy, balneotherapy, and spa therapy on blood pressure. We searched the PubMed/MEDLINE, Web of Science, Scopus, and Science Direct databases until April 2022 using related keywords. In summary, the current study shows that different hydrotherapy methods may improve blood pressure. Hydrotherapy as one of the adjunctive therapy methods can be effective in lowering blood pressure. Blood circulation is smoothed by the warmth of the water. This improvement may be achieved by regulating heart rate, releasing hormones that control blood pressure, or regulating the activity of baroreceptors or chemoreceptors. In addition to using medications, hypertension patients also use non-pharmacological approaches in their care, including hydrotherapy, balneotherapy, and warm water foot soaks performed at home. Although several lines of evidence show the potential effects of hydrotherapy, balneotherapy, and spa therapy on blood pressure, many clinical trials are needed.

A preliminary investigation of the impact of artificially carbonated water bathing on canine skin physiological and barrier function

BACKGROUND

The effect of carbon dioxide (CO₂ )-rich water bathing on the skin has been studied extensively in humans. However, there have been few studies evaluating the impact of CO₂ -rich water bathing on canine skin physiology and barrier functions.

OBJECTIVES

To evaluate the impact of artificially carbonated water (ACW) bathing on skin parameters in healthy beagles.

ANIMALS

Six healthy beagles with no history of skin disease.

MATERIALS AND METHODS

Body temperature, skin temperature, transepidermal water loss (TEWL), skin hydration and skin blood flow were evaluated before and after single ACW bathing (37°C, 20 min) with a CO₂ concentration of >1000 ppm.

RESULTS

After ACW bathing, skin blood flow significantly increased (p < 0.0001), yet there were no significant changes in body temperature (p = 0.3124), skin temperature (p = 0.4911), TEWL (p = 0.5167) or skin hydration (p = 0.3084). There were no adverse events during the trials.

CONCLUSIONS AND CLINICAL IMPORTANCE

Artificially carbonated water water bathing could potentially increase skin blood flow without affecting skin temperature, body temperature and skin barrier function in dogs, similar to its effects in humans.

Thermoregulation and thermal sensation during whole-body water immersion at different water temperatures in healthy individuals: A scoping review

BACKGROUND

Severe thermal discomfort may increase risk of drowning due to hypothermia or hyperthermia from prolonged exposure to noxious water temperatures. The importance of using a behavioral thermoregulation model with thermal sensation may predict the thermal load that the human body receives when exposed to various immersive water conditions. However, there is no thermal sensation "gold standard" model specific for water immersion. This scoping review aims to present a comprehensive overview regarding human physiological and behavioral thermoregulation during whole-body water immersion and explore the feasibility for an accepted defined sensation scale for cold and hot water immersion.

METHODS

A standard literary search was performed on PubMed, Google Scholar, and SCOPUS. The words "Water Immersion," "Thermoregulation," "Cardiovascular responses" were used either as independent searched terms and MeSH terms (Medical Subject Headings) or in combination with other text words. The inclusion criteria for clinical trials terms to thermoregulatory measurements (core or skin temperature), whole-body immersion, 18-60 years old and healthy individuals. The prementioned data were analyzed narratively to achieve the overall study objective.

RESULTS

Twenty-three published articles fulfilled the review inclusion/exclusion criteria (with nine measured behavioral responses). Our outcomes illustrated a homogenous thermal sensation in a variety of water temperatures ranges, that was strongly associated with thermal balance, and observed different thermoregulatory responses. This scoping review highlights the impact of water immersion duration on human thermoneutral zone, thermal comfort zone, and thermal sensation.

CONCLUSION

Our findings enlighten the significance of thermal sensation as a health indicator for establishing a behavioral thermal model applicable for water immersion. This scoping review provides insight for the needed development of subjective thermal model of thermal sensation in relation to human thermal physiology specific to immersive water temperature ranges within and outside the thermal neutral and comfort zone.

Comparison of low-concentration carbon dioxide-enriched and tap water immersion on body temperature after passive heating

Background

Because carbon dioxide (CO₂)-enriched water causes cutaneous vasodilation, immersion in CO₂-enriched water facilitates heat transfer from the body to the water or from the water to the body. Consequently, immersion in CO₂-enriched water raises or reduces body temperature faster than immersion in fresh water. However, it takes time to dissolve CO₂ in tap water and because the dissolved CO₂ concentration decreases over time, the actual CO₂ concentration is likely lower than the stated target concentration. However, it is unclear whether water containing a lower CO₂ concentration would also cool the body faster than fresh water after body temperature had been increased.

Methods

Ten healthy males (mean age = 20 ± 1 years) participated in the study. Participants were first immersed for 15 min in a tap water bath at 40 °C to raise body temperature. They then moved to a tap water or CO₂-enriched water bath at 30 °C to reduce body temperature. The CO₂ concentration was set at 500 ppm. The present study measured cooling time and cooling rate (slope of the regression line relating auditory canal temperature (T_ac) to cooling time) to assess the cooling effect of CO₂-enriched water immersion.

Results

Immersion in 40 °C tap water caused T_ac to rise 0.64 ± 0.25 °C in the tap water session and 0.62 ± 0.27 °C in the CO₂-enriched water session (P > 0.05). During the 30 °C water immersion, T_ac declined to the baseline within 13 ± 6 min in tap water and 10 ± 6 min in CO₂-enriched water (P > 0.05). Cooling rates were 0.08 ± 0.06 °C/min in tap water and 0.08 ± 0.04 °C/min in CO₂-enriched water (P > 0.05).

Conclusions

CO₂-enriched water containing 500 ppm CO₂ did not cool faster than tap water immersion. This suggests that when the water temperature is 30 °C, a CO₂ concentration of 500 ppm is insufficient to obtain the advantageous cooling effect during water immersion after body temperature has been increased.

Clinical efficacy of artificially carbonated water bathing on superficial bacterial folliculitis in dogs

BACKGROUND

Bathing with artificially carbonated water is reported to be a valuable therapeutic option for various human skin disorders.

OBJECTIVE

To evaluate the clinical efficacy of artificially carbonated water bathing on superficial bacterial folliculitis (SBF) caused by Staphylococcus pseudintermedius (SP) in dogs.

ANIMALS

Nineteen dogs with SBF from whom SP was isolated from skin lesions were enrolled.

METHODS AND MATERIALS

Dogs with SBF were allocated randomly to either the artificially carbonated water bathing group or the control group bathed with tap water. The dogs were bathed with the designated water type on day (D)0, D7 and D14. Clinical scores and skin surface pH were evaluated on D0 and D21. Colony forming unit (cfu) assays were performed in vitro to investigate whether the artificially carbonated water affected growth of clinical SP isolates.

RESULTS

The mean rate of improvement in the clinical scores was significantly higher in the carbonated water group than in the control group. Dogs bathed with carbonated water exhibited significant decreases in their skin surface pH after bathing; dogs bathed with tap water did not. No dogs experienced significant adverse events. The cfus of SP incubated in vitro with artificially carbonated water did not significantly differ from those incubated with tap water.

CONCLUSION

Bathing with artificially carbonated water might be an effective and safe adjunctive therapy for canine SP-induced SBF.

Effect of Artificial Carbon Dioxide-Rich Water Immersion on Peripheral Blood Flow in Healthy Volunteers: Preliminary Study about Artificial Carbon Dioxide-Rich Water

BACKGROUND: Peripheral blood circulation disorder is one of the global health problems. Balneotherapy that uses CO2 springs may be one of the complementary treatment options. The device to produce artificial CO2-rich water is needed to achieve an improvement effect, at least almost like the improvement effect of natural balneotherapy. AIM: This study aims to investigate the effect of artificial CO2-rich water immersion on peripheral blood flow using Bicarbonated JesC CREA BC-2000. METHODS AND MATERIALS: Thirty-nine healthy volunteers participated in this study. Each subject immersed both of their legs in a mixed solution from water and CO2 at temperature 38°C. This solution was mixed using a device, namely, “Bicarbonated JesC CREA BC-2000”. Peripheral blood flow was measured for 5 min before immersion (in this study, we denoted it as the mean basal blood flow), 10 min during immersion, and 5 min after immersion using pocket JMS laser Doppler flowmetry MBF-IIA. Repeated analysis of variance was used for statistical analysis. RESULTS: There is the difference in peripheral blood flow among before, during, and after immersing the legs into artificial CO2-rich water using Bicarbonated JesC CREA BC-2000 (p < 0.001). CONCLUSION: Bicarbonated JesC CREA BC-2000 may be used as the device to produce an artificial CO2-rich water bath that may affect peripheral blood flow in healthy volunteers.

Efficacy of CO₂ Infusion for Preoperative Computed Tomographic Angiography with Computed Tomographic Colonography

BACKGROUND Computed tomographic colonography (CTC) is useful for patients for whom colonoscopy may be difficult to perform and is widely employed to examine the vasculature prior to colorectal cancer surgery. Computed tomographic angiography (CTA) was shown to be beneficial intraoperatively to manipulate blood vessels and prevent vascular injury. Three-dimensional (3D)-CTA combined with CTC (3D-CTA with CTC) is useful for preoperative evaluations of the anatomy of mesenteric vessels, colon, and lymph nodes. We observed that when the intestine was dilated with carbon dioxide (CO₂), the arteriovenous delineation was often more pronounced than without CO₂. To clarify the effects of gas injection with and without CO₂ on hemodynamics and vascular passage, we compared the effect of contrast for blood vessels. MATERIAL AND METHODS Thirty patients with resectable colorectal cancer who underwent a preoperative CT examination at our institution from January to October 2019 were study participants. Of these, 15 underwent 3D-CTA and 15 had 3D-CTA with CTC. Three board-certified radiologists independently and blindly evaluated 18 blood vessels. CT values for each blood vessel were measured on each image. RESULTS CT values for 3D-CTA with CTC were significantly higher with CO₂ than without CO₂. The quality of 3D-CTA with CTC images for visualization of blood vessels was also significantly greater than that of 3D-CTA, especially those of arterial and intramesenteric venous systems. CONCLUSIONS Based on the higher image quality and CT values obtained by 3D-CTA with CTC for vessels, compared with by 3D-CTA imaging, 3D-CTA with CTC imaging might be useful in evaluating colorectal cancers.

Thermal Disparity among Fingers and Its Amelioration by CO2-Water Bathing in Connective Tissue Disease Patients

Objective. Correlation between a low finger temperature and thermal disparity among fingers was studied in connective tissue disease (CTD) patients. Whether the thermal disparity may be ameliorated by hand immersion in a warm carbon dioxide- (CO2-) water bath was analyzed. Methods. CTD patients with suspected peripheral circulation disorder underwent a thermography test. From before to 30 min after hand immersion in CO2-water (CO2 bathing; 1000 ppm CO2, 42°C, 10 min), the nailfold temperatures were measured. The mean temperature (m-Temp) and the coefficient of variation of the temperature ( $\text{CV}=\text{SD}/\text{m}‐\text{Temp}$ of one hand; the mean of CVs of both hands was adopted as the indicator of thermal disparity) were monitored. The correlation between m-Temp and CV was also analyzed. Results. Forty-seven (45 females and 2 males) patients were included, 32 of whom had Raynaud’s phenomenon. The m-Temp was $30.8\pm {3.0}^{°}C$ at the baseline, increased to $35.3\pm {1.0}^{°}\text{C}$ immediately after CO2 bathing, and remained significantly higher than that at the baseline until 30 min after ( $32.1\pm {1.9}^{°}\text{C}$ ). The CV was $0.0291\pm 0.0247$ at the baseline, decreased to $0.0135\pm 0.0039$ immediately after CO2 bathing, and remained significantly lower than the baseline until 30 min after ( $0.0163\pm 0.0143$ ). Between m-Temp and CV, a negative correlation was observed throughout the measurements. Conclusion. Thermal disparity was observed at baseline measurement in CTD patients. Warm CO2 bathing markedly ameliorated the disparity, and this amelioration remained until after 30 min. Throughout the observation, the lower the m-Temp, the more severe the thermal disparity among fingers.

A novel cooling method using carbon dioxide-rich water after passive heating

In the event of a marked rise in body temperature, it is often necessary to reduce the temperature quickly. One method to rapidly drop body temperature is cold water immersion. Because carbon dioxide (CO₂)-rich water causes cutaneous vasodilation, it may be that CO₂-rich water reduces body temperature faster than fresh water. To test that idea, I compared the effects of CO₂-rich and tap water immersion on auditory canal temperature (T_ac) after passive heating. Nine healthy male subjects participated in the study. Subjects were first immersed for 15 min in a tap water bath at 40 °C to raise body temperature. They then moved to a tap water or CO₂-rich water bath at 30 °C to reduce body temperature. Immersion in 40 °C tap water caused T_ac to rise 0.64 ± 0.11 °C in the tap water session and 0.71 ± 0.25 °C in the CO₂-rich water session (P > 0.05). During the 30 °C water immersion, T_ac declined and was significantly lower in CO₂-rich water than in tap water. Cooling rates were 0.06 ± 0.04 °C/min in tap water and 0.11 ± 0.05 °C/min in CO₂-rich water (P < 0.05). In addition, both thermal sensation (3.2 ± 1.0 vs. 2.1 ± 0.9; P < 0.01) and thermal comfort (1.2 ± 0.4 vs. 2.1 ± 0.8; P < 0.01) were significantly better in CO₂-rich water than tap water. These results suggest that CO₂-rich water immersion reduces T_ac 1.7 times faster than tap water immersion, and that CO₂-rich water immersion cools the body more comfortably than tap water immersion.

Temperature-dependent effects on CO2 water bath therapy induced changes in blood flow and vascularity in hind limb ischemia

To test if magnitudes of the beneficial actions of CO₂ water bath therapy on blood flow and vascular density are dependent upon temperature, ischemia in the hind limb of rats was induced by occluding the left femoral artery for 2 weeks and the animals were exposed to water bath therapy with or without CO₂ at 34 or 41 °C for 4 weeks (20 min treatment each day for 5 days/week). CO₂ water bath therapy at 34 °C increased peak, minimal, and mean blood flow by 190%-600% in the ischemic limb. On the other hand, CO₂ water bath treatment at 41 °C increased these parameters of blood flow by 37%, 55%, and 41%, respectively, in the ischemic limb. The small blood vessel count, an index of vascular density, in the ischemic limb was increased by CO₂ water bath therapy at 34 and 41 °C by 32% and 122%, respectively. No changes in the ischemic animals by CO₂ water bath therapy at 34 or 41 °C were observed in the heart rate, R-R interval, and plasma lipid or glucose levels. These data indicate that the beneficial effect of CO₂ water bath therapy at 34 °C on blood flow in the ischemic muscle is greater whereas that on vascular density is smaller than changes in these parameters at 41 °C.

Facial application of high-concentration carbon dioxide prevents epidermal impairment associated with environmental changes

Purpose

The transdermal application of carbon dioxide (CO₂) gas dissolved in a solution and bathing in carbonated springs have been known to improve circulatory disorders. We aimed to elucidate and profile the effects of CO₂ application on local skin function.

Patients and methods

A liquid formulation that included high-concentration CO₂ or a control formulation was applied to the face of healthy men for 8 weeks. Quantitative analysis was performed during the dry winter months.

Results

At the site where the control formulation was applied, transepidermal water loss (TEWL) increased while the moisturizing function (conductance) of facial skin decreased during the study period. However, at the CO₂-treated site, increases in TEWL and decreases in conductance were significantly suppressed. In addition, the deterioration in scaliness and wrinkles parameters were suppressed by ≥40% at the CO₂-treated site. There were no significant differences in skin surface pH or color properties between the control and test sites.

Conclusion

This study suggests that the continuous application of a high-concentration CO₂ formulation can affect skin physiology and has the potential to suppress reductions in the barrier and moisturizing functions of the stratum corneum accompanied by desquamation, which occurs during the winter.

Effect of leg immersion in mild warm carbonated water on skin and muscle blood flow

Leg immersion in carbonated water improves endothelial-mediated vasodilator function and decreases arterial stiffness but the mechanism underlying this effect remains poorly defined. We hypothesized that carbonated water immersion increases muscle blood flow. To test this hypothesis, 10 men (age 21 ± 0 years; mean ± SD) underwent lower leg immersion in tap or carbonated water at 38°C. We evaluated gastrocnemius muscle oxyhemoglobin concentration and tissue oxygenation index using near-infrared spectroscopy, skin blood flow by laser Doppler flowmetry, and popliteal artery (PA) blood flow by duplex ultrasound. Immersion in carbonated, but not tap water elevated PA (from 38 ± 14 to 83 ± 31 mL/min; P < 0.001) and skin blood flow (by 779 ± 312%, P < 0.001). In contrast, lower leg immersion elevated oxyhemoglobin concentration and tissue oxygenation index with no effect of carbonation (P = 0.529 and P = 0.495). In addition, the change in PA blood flow in response to immersion in carbonated water correlated with those of skin blood flow (P = 0.005) but not oxyhemoglobin concentration (P = 0.765) and tissue oxygenation index (P = 0.136) while no relations was found for tap water immersion. These findings indicate that water carbonation has minimal effect on muscle blood flow. Furthermore, PA blood flow increases in response to lower leg immersion in carbonated water likely due to a large increase in skin blood flow.

Acute vascular effects of carbonated warm water lower leg immersion in healthy young adults

Endothelial dysfunction is associated with increased cardiovascular mortality and morbidity; however, this dysfunction may be ameliorated by several therapies. For example, it has been reported that heat‐induced increases in blood flow and shear stress enhance endothelium‐mediated vasodilator function. Under these backgrounds, we expect that carbon dioxide (CO₂)‐rich water‐induced increase in skin blood flow improves endothelium‐mediated vasodilation with less heat stress. To test our hypothesis, we measured flow‐mediated dilation (FMD) before and after acute immersion of the lower legs and feet in mild warm (38°C) normal or CO₂‐rich tap water (1000 ppm) for 20 min in 12 subjects. Acute immersion of the lower legs and feet in mild warm CO₂‐rich water increased FMD (P < 0.01) despite the lack of change in this parameter upon mild warm normal water immersion. In addition, FMD was positively correlated with change in skin blood flow regardless of conditions (P < 0.01), indicating that an increase in skin blood flow improves endothelial‐mediated vasodilator function. Importantly, the temperature of normal tap water must reach approximately 43°C to achieve the same skin blood flow level as that obtained during mild warm CO₂‐rich water immersion (38°C). These findings suggest that CO₂‐rich water‐induced large increases in skin blood flow may improve endothelial‐mediated vasodilator function while causing less heat stress.

Carbon dioxide water-bath treatment augments peripheral blood flow through the development of angiogenesis

In this study, we investigated the effects of CO₂ water-bath therapy on blood flow and angiogenesis in the ischemic hind limb, as well as some plasma angiogenic factors in peripheral ischemic model. The hind limb ischemia was induced by occluding the femoral artery for 2 weeks in rats and treated with or without CO₂ water-bath therapy at 37 °C for 4 weeks (20 min treatment every day for 5 days per week). The peak blood flow and minimal and mean blood flow in the ischemic skeletal muscle were markedly increased by the CO₂ water-bath therapy. This increase in blood flow was associated with development of angiogenesis in the muscle, as well as reduction in the ischemia-induced increase in plasma malondialdehyde levels. Although plasma vascular endothelial growth factor and nitric oxide levels were increased in animals with peripheral ischemia, the changes in these biomarkers were not affected by CO₂ water-bath therapy. These results suggest that augmentation of blood flow in the ischemic hind limb by CO₂ water-bath therapy may be due to the development of angiogenesis and reduction in oxidative stress.

Suppression of phosphorylated MAPK and caspase 3 by carbon dioxide

Although CO₂ is produced during the oxidation of different substrates in all types of cells, the role of this gas in the regulation of cellular function is not clearly understood. Since changes in several signal transduction as well as apoptotic, anti-apoptotic, and other proteins are known to modify cellular function, we investigated if some of these proteins are altered upon incubating the rat hind leg skeletal muscle in a medium enriched with CO₂ (1000-1200 ppm) for 30 min. CO₂ was observed to depress phosphorylated levels of ERK1 (P44) and ERK2 (P42) without affecting the unphosphorylated content of these MAPK proteins. On the other hand, no change in p38 MAPK protein was found but the content of its degradation product 30 kDa proteins (both phosphorylated and unphosphorylated) was decreased. No alterations in the content of other signaling proteins (PKA and Akt), inflammatory molecule (TNF-α), and vascular endothelial growth factor (VEGF) were seen upon exposure of the muscle to CO₂. The content for apoptotic and anti-apoptotic proteins (Bad and Bcl2), except for a decrease in caspase 3, were also not affected by CO₂. These results indicate that CO₂ may serve as a gasotransmitter to regulate cellular function by depressing MAPK and caspase 3 activities.

Transdermal CO2 Application in Chronic Wounds

Chronic wounds are a challenge to treatment. In this retrospective study, the effect of transdermal CO2 application on wound healing in chronic ulcers was investigated and compared to the effect of CO2 on acute surgical wounds. Eightysix patients (52 females and 34 males) with chronic wounds of different origin except arterial occlusive disease were included. In addition, 17 patients (5 females, 12 males) with wide excision wounds after surgical therapy of acne inversa were considered. The indication for CO2 application was a wound at risk for infection. Treatment was performed with a Carboflow® device once daily for 30 to 60minutes. Therewas clinical evidence of improvement of granulation and reductionof discharge and malodor within 1 week of treatment in both chronic and acute wounds. Only 9 patients, all diabetics, needed an additional systemic antibiosis. The treatment was well tolerated. No adverse effects have been noted. Transdermal CO2 application is a useful method to reduce the risk of infection and improve wound healing in both chronic and certain acute wounds. Systematic prospective trials are needed.

t-Flavanone Improves the Male Pattern of Hair Loss by Enhancing Hair-Anchoring Strength: A Randomized, Double-Blind, Placebo-Controlled Study

Introduction

trans-3,4′-Dimethyl-3-hydroxyflavanone (t-flavanone) is a derivative of astilbin that actively stimulates hair growth. The aim of the present study was to identify the mechanisms of action of t-flavanone on hair growth.

Methods

A double-blind usage test was performed with healthy volunteers who had androgenic alopecia (AGA). The subjects were divided into three groups with equal average baldness. The members in each group applied a vasodilator-containing hair lotion supplemented with either 0, 0.1, or 0.3% (wt) t-flavanone twice a day for 30 weeks. The efficacy of t-flavanone was evaluated based on the parietal global and microscopic images. At week 30, the anchoring strength of hair was measured by the average peak force required for plucking out a single hair in a non-bald area using a digital force gauge. Desmoglein expression in the cultured human hair follicle was analyzed by Western blotting.

Results

After 30 weeks, t-flavanone significantly improved AGA and enhanced the hair-anchoring strength in a hair diameter-independent manner. Culture of human hair follicles in vitro with t-flavanone resulted in the upregulation of desmoglein protein expression.

Conclusions

The results of our in vivo and in vitro studies demonstrated that t-flavanone enhanced the cell-cell adhesions in hair follicles; thus, reinforcement of hair rooting may be a mechanism by which t-flavanone promotes hair growth.

Funding

Kao Corp.

Percutaneous carbon dioxide mist treatment has protective effects in experimental myocardial infarction

Percutaneous treatment with carbon dioxide (CO2) mist, CO2 gas dissolved in water, contributes to improved cardiac function after myocardial infarction (MI). In this study, we investigated the effects of repeated pretreatment with CO2 mist on cardiac dysfunction after MI. The CO2 mist was generated by a dry mist production unit. The whole body of rats below the axilla was wrapped in a polyethylene bag, which was sealed and filled with the CO2 mist in the draft cabinet for 30 min daily for 7 days. MI was induced by ligation of the coronary artery in untreated (UT), CO2 gas-pretreated (CG), and CO2 mist-pretreated (CM) rats. The infarct size and the increase in oxidative stress due to MI were significantly smaller in the CM rats than in the UT rats. Furthermore, the expression of inflammation-related genes, such as monocyte chemoattractant protein-1, and fibrosis-related genes, such as transforming growth factor-β1, was significantly suppressed in the CM rats. The CM rats had a better left ventricular ejection fraction than the UT rats 7 days after MI. These parameters in the CG rats were the same as in the UT group. Thus, CO2 mist preparative treatment may be potentially useful for the reduction of MI.

Novel device that produces carbon dioxide mist for myocardial infarction treatment in rats

BACKGROUND

Carbon dioxide (CO(2)) baths have been used to treat a variety of diseases, but developing an artificial bath of highly concentrated CO(2) is difficult. Here, we tried the efficacy of a novel device instead of a CO(2) bath.

METHODS AND RESULTS

Using a device equipped with double fluid nozzles, CO(2) gas and H(2)O were compounded and compressed at 4 barometric pressures. As a result, CO(2) gas was dissolved in H(2)O, which contained a few micrometers of CO(2) particles, namely, a CO(2) mist. Wistar rats with myocardial infarction (MI) by ligation of the left coronary artery were percutaneously administered CO(2) mist or CO(2) gas alone or no treatment for 30 min daily. With regard to tissue blood flow during treatment, the group treated with CO(2) mist had significantly increased tissue oxygenated hemoglobin levels and tissue saturation levels, and significantly decreased deoxygenated hemoglobin levels compared with the group treated with CO(2) gas. After 4 weeks treatment, the group treated with CO(2) mist had a significantly improved ejection fraction by echocardiography compared with the untreated group. Interestingly, the group treated with CO(2) mist had significantly increased nitrate concentrations in serum and vascular endothelial growth factor mRNA expression levels in the myocardium compared with the untreated group.

CONCLUSIONS

Our new mist production device may be potentially useful for the treatment of heart failure caused by MI.

Carbon dioxide balneotherapy and cardiovascular disease

Carbon dioxide (CO(2)) balneotherapy is a kind of remedy with a wide spectrum of applications which have been used since the Middle Ages. However, its potential use as an adjuvant therapeutic option in patients with cardiovascular disease is not yet fully clarified. We performed a thorough review of MEDLINE Database, EMBASE, ISI WEB of Knowledge, COCHRANE database and sites funded by balneotherapy centers across Europe in order to recognize relevant studies and aggregate evidence supporting the use of CO(2) baths in various cardiovascular diseases. The three main effects of CO(2) hydrotherapy during whole body or partial immersion, including decline in core temperature, an increase in cutaneous blood flow, and an elevation of the score on thermal sensation, are analyzed on a pathophysiology basis. Additionally, the indications and contra-indications of the method are presented in an evidence-based way, while the need for new methodologically sufficient studies examining the use of CO(2) baths in other cardiovascular substrates is discussed.

Crenotherapy: a neglected resource for human health now re-emerging on sound scientific concepts

Recent mechanistic evidence demonstrates that spa-based therapy (or, as we propose, crenotherapy from the Greek word kapparhoepsilonnueta, spring fountain) is indeed based on solid scientific data. This mini-review highlights the latest insights into the mechanisms of crenotherapy derived from in vitro experiments, studies on animal models, and carefully designed clinical trials. Although more basic and clinical data are still needed, crenotherapy is coming of age as a modern, scientifically sound therapy. As the underlying mechanisms are uncovered, it is becoming possible to choose the most appropriate applications of this centuries-old practice, possibly reducing medical costs, thus explaining the current worldwide renewed interest in crenotherapy.

Effects of immersion in water containing high concentrations of CO2 (CO2-water) at thermoneutral on thermoregulation and heart rate variability in humans

Immersion in high concentrations of CO2 dissolved in freshwater (CO2-water) might induce peripheral vasodilatation in humans. In this study, we investigated whether such immersion could affect the autonomic nervous system in humans using spectral analysis of heart rate variability. Ten healthy men participated in this study. Tympanic temperature, cutaneous blood flow and electrocardiogram (ECG) were measured continuously during 20 min of immersion in CO2-water. The ECG was analyzed by spectral analysis of R-R intervals using the maximal entropy method. The decrease in tympanic temperature was significantly greater in CO2-water immersion than in freshwater immersion. Cutaneous blood flow at the immersed site was significantly increased with CO2-water immersion compared to freshwater. The high frequency component (HF: 0.15-0.40 Hz) was significantly higher in CO2-water immersion than in freshwater immersion, but the low frequency (LF: 0.04-0.15 Hz) /high frequency ratio (LF/HF ratio) was significantly lower in CO2-water immersion than in freshwater immersion. The present study contributes evidence supporting the hypothesis that CO2-water immersion activates parasympathetic nerve activity in humans.

Immersion in CO2-rich water containing NaCl diminishes blood pressure fluctuation in anesthetized rats

Remarkably, bathing in hot springs containing high concentrations of carbon dioxide (CO(2)) influences cardiovascular function more than bathing in fresh water. The CO(2)-enriched water in hot springs generally contains many salts, whose interactions remain unknown. We separately evaluated the actions of individual factors in CO(2)-enriched water and confirmed that CO(2) and NaCl have combined effects on blood pressure fluctuations in anesthetized rats. Animals equipped with sensor probes to monitor body temperature, skin blood flow and arterial blood pressure were immersed in bathwater (35 degrees C) containing CO(2) with NaCl, KCl or sucrose. The effects of these factors on cardiovascular function were evaluated using power-spectral analysis of fluctuations in blood pressure and heart rate. Compared with immersion in tap water, heart rate and skin vascular resistance were reduced during immersion in CO(2)-enriched water irrespective of the presence of other components. In terms of the very low frequency range (0.02-0.195 Hz), the power of blood pressure fluctuation during immersion was significantly reduced when the CO(2)-enriched water contained more than 1.5% NaCl but was not influenced by other components of similar osmotic pressure and the same specific gravity. The results indicated that the coexistence of CO(2) and sodium ions in bathwater reduce blood pressure fluctuations, and suggested that this combination effect of CO(2) and salt contributes to the sedative effect on human cardiovascular functions while bathing in CO(2)-hot springs.

Spinal cord transection inhibits HR reduction in anesthetized rats immersed in an artificial CO2-hot spring bath

Like humans, the heart rate (HR) of anesthetized rats immersed in CO(2)-water is lower than that when immersed in tap water at the same temperature. To investigate the afferent signal pathway in the mechanism of HR reduction, Wistar rats were anesthetized with urethane and then the spinal cord was transected between T(4) and T(5). The animals were immersed up to the axilla in a bathtub of tap-water (CO(2) contents: 10-20 mg.l(-1)) or of CO(2)-water (965-1,400 mg.l(-1)) at 35 degrees C while recording HR, arterial blood pressure, and arterial blood gas parameters (PaCO(2), PaO(2), pH). Arterial blood gas parameters did not change during immersion, irrespective of CO(2) concentration of the bath water, whereas the HR was reduced in the CO(2)-water bath. The inhalation of CO(2)-mixed gas (5% CO(2), 20% O(2), 75% N(2)) resulted in increased levels of blood gases and an increased HR during immersion in all types of water tested. The HR reduction observed in sham transected control animals immersed in CO(2)-water disappeared after subsequent spinal cord transection. These results show that the dominant afferent signal pathway to the brain, which is involved in inducing the reduced HR during immersion in CO(2)-water, is located in the neuronal route and not in the bloodstream.

Combined Inpatient Rehabilitation and Spa Therapy for Breast Cancer Patients

The present study investigated the changes of quality of life, mood, and the tumor marker CA 15-3 associated with a 3-week inpatient breast cancer rehabilitation program incorporating spa therapy. One hundred forty-nine women, 32 to 82 years, participated in the study 3 to 72 months after breast cancer surgery. Quality of life (QoL, EORTC QLQ-C30), anxiety, and depression (HADS) were measured 2 weeks before, at the end, and 6 months after rehabilitation; CA 15-3 at the beginning, end, and at 6 months follow-up. Patients received an individualized rehabilitation program incorporating manual lymph drainage, exercise therapy, massages, psychological counseling, relaxation training, carbon dioxide baths, and mud packs. Quality of life and mood improved significantly, the greatest short-term improvements found for mood-related aspects of quality of life, the most lasting improvements found for physical complaints (eg, fatigue). Also, the tumor marker CA 15-3 declined significantly to follow-up. Patient characteristics, as well as the time since surgery, moderated rehabilitation outcome to a limited extent. Older patients, nonobese patients, patients with a greater lymphedema, and patients with an active coping style showed slightly greater improvements. Hot mud packs inducing hyperthermia did not affect CA 15-3. In conclusion, the combination of inpatient rehabilitation with spa therapy provides a promising approach for breast cancer rehabilitation.

Decrease in heart rates by artificial CO2 hot spring bathing is inhibited by beta1-adrenoceptor blockade in anesthetized rats

To investigate the effects of carbon dioxide (CO2) hot spring baths on physiological functions, head-out immersion of urethane-anesthetized, fursheared male Wistar rats was performed. Animals were immersed in water (30 or 35 degrees C) with high-CO2 content ( approximately 1,000 parts/million; CO2-water). CO2-water for bathing was made by using an artificial spa maker with normal tap water and high-pressure CO2 from a gas cylinder. When a human foot was immersed for 10 min in the CO2-water at 35 degrees C, the immersed skin reddened, whereas skin color did not change in normal tap water at the same temperature. Arterial blood pressure, heart rate (HR), underwater skin tissue blood flow, and temperatures of the colon and immersed skin were continuously measured while animals were immersed in a bathtub of water for approximately 30 min at room temperature (26 degrees C). Immersed skin vascular resistance, computed from blood pressure and tissue blood flow, was significantly lower in the CO2-water bath than in tap water at 30 degrees C, but no differences were apparent at 35 degrees C. HR of rats in CO2-water was significantly slower than in tap water at 35 degrees C. Decreased HR in CO2-water was inhibited by infusion of atenolol (beta1-adrenoceptor blocker), but it was unaffected by atropine (muscarinic cholinoceptor blocker). Theses results suggest that bradycardia in CO2 hot spring bathing is caused by inhibition of the cardiac sympathetic innervation. This CO2-water maker should prove a useful device for acquiring physiological evidence of balneotherapy.