Hyperbaric oxygen improves ultraviolet B irradiation-induced melanin pigmentation and diminishes senile spot size

Hyperbaric Oxygen Therapy in Plastic, Aesthetic, and Reconstructive Surgery: Systematic Review

Introduction: Hyperbaric oxygen therapy (HBOT) has been used over the past six decades to treat multiple conditions. This systematic review aims to identify and evaluate the clinical outcomes of hyperbaric oxygen therapy in the field of plastic, reconstructive, and aesthetic surgery, found in the literature from the year 2000 to the present. Methods: A systematic review of the literature focused on the conceptual and methodological aspects of the PRISMA Declaration. The search for clinical trials focused on the results of hyperbaric therapy in plastic, reconstructive, and cosmetic surgery. The Newcastle–Ottawa scale suggested by the Cochrane manual was applied to each study. The study was carried out with a defined protocol and was registered in PROSPERO, with code CRD42022301261. Results: From the 170 articles identified, 6 were selected. Five of them showed that hyperbaric oxygen therapy favored the reduction of the size of skin ulcers and increased the formation of granulation tissue (two trials; p < 0.05), increased the partial pressure of transcutaneous oxygen in patients with free flaps (one trial; p < 0.001), reduced perfusion in keloid scarring disorder (one trial; p < 0.01), and accelerated both the fading of melanin pigmentation and the decrease in age spot size (one trial; p < 0.05). The methodological quality was moderate in all cases because there was no blinding method reported. One study failed to find differences in flap survival, time to resolution of venous congestion, resolution of edema, and postoperative recovery period (p > 0.05). Conclusions: Hyperbaric oxygen therapy has been increasingly used in the field of plastic and reconstructive surgery, and has shown potential benefits in promoting wound healing, reducing the risk of infection, and improving the survival of tissues used in reconstructive procedures. Further research with more rigorous clinical trials is needed to fully understand the efficacy and optimal use of this therapy in the field of plastic and reconstructive surgery.

Hyperbaric oxygen therapy for healthy aging: From mechanisms to therapeutics

Hyperbaric oxygen therapy (HBOT), a technique through which 100% oxygen is provided at a pressure higher than 1 atm absolute (ATA), has become a well-established treatment modality for multiple conditions. The noninvasive nature, favorable safety profile, and common clinical application of HBOT make it a competitive candidate for several new indications, one of them being aging and age-related diseases. In fact, despite the conventional wisdom that excessive oxygen accelerates aging, appropriate HBOT protocols without exceeding the toxicity threshold have shown great promise in therapies against aging. For one thing, an extensive body of basic research has expanded our mechanistic understanding of HBOT. Interestingly, the therapeutic targets of HBOT overlap considerably with those of aging and age-related diseases. For another, pre-clinical and small-scale clinical investigations have provided validated information on the efficacy of HBOT against aging from various aspects. However, a generally applicable protocol for HBOT to be utilized in therapies against aging needs to be defined as a subsequent step. It is high time to look back and summarize the recent advances concerning biological mechanisms and therapeutic implications of HBOT in promoting healthy aging and shed light on prospective directions. Here we provide the first comprehensive overview of HBOT in the field of aging and geriatric research, which allows the scientific community to be aware of the emerging tendency and move beyond conventional wisdom to scientific findings of translational value.

Effect of Active Groups and Oxidative Dimerization on the Antimelanogenic Activity of Catechins and Their Dimeric Oxidation Products

Some catechins and their dimeric oxidation products are well known to possess antimelanogenic activity, which could be influenced by their structures and oxidative dimerization. This study compared the antimelanogenic activity of different catechins and dimeric oxidation products and clarified the mechanism using an α-MSH-stimulated B16F10 cell model. It was found that 100 μg/mL (-)-gallocatechin gallate, (-)-epigallocatechin gallate, theasinensin A, and theaflavine-3,3'-digallate could significantly inhibit melanin synthesis without cytotoxicity. The tyrosinase (TYR) activities were 26.24 ± 4.97, 31.57 ± 5.37, 66.10 ± 9.62, and 78.19 ± 5.14%, respectively, and the melanin contents were 38.29 ± 3.50, 41.21 ± 7.62, 62.13 ± 9.80, and 68.82 ± 11.62%, respectively. These compounds inhibit melanin production by attenuating the mRNA levels of TYR, TRP1, and TRP2 gene. The structure-activity relationship showed that geometrical isomerism was not the key factor affecting catechins' antimelanogenic activity. Compared with the catechol, catechins with B-ring pyrogallol inhibited melanin synthesis more effectively. The number of galloyl groups was positively correlated with antimelanogenic activity. Compared with 3-galloyl, 3'-galloyl was a stronger active group in antimelanogenesis. Interestingly, the contribution of B-ring pyrogallol to the antimelanogenic activity was significantly stronger than that of 3-galloyl in catechins. Additionally, the antimelanogenic activity of the dimeric oxidation product at 100 μM was more than or equal to that of individual substrate-catechin, while being significantly less than that of the substrate-catechin mixture. Results indicated that pyrogallol and galloyl were the active groups inhibiting melanin synthesis. The oxidative dimerization weakened the antimelanogenic activity of the substrate-catechin mixture.

Mild hyperbaric oxygen: mechanisms and effects

Adequate oxygen supply by exposure to mild hyperbaric oxygen at appropriately high atmospheric pressure (1266-1317 hPa) and increased oxygen concentration (35-40% oxygen) has a possibility of improving the oxidative metabolism in cells and tissues without barotrauma and excessive production of reactive oxygen species. Therefore, metabolic syndrome and lifestyle-related diseases, including type 2 diabetes and hypertension, in rats were inhibited and/or improved by exposure to mild hyperbaric oxygen. It accelerated the growth-induced increase in oxidative capacity of the skeletal muscle in rats and inhibited the age-related decrease in oxidative capacity of the skeletal muscle in mice. A decrease in dopaminergic neurons in the substantia nigra of mice with Parkinson's disease was inhibited by exposure to mild hyperbaric oxygen. This review describes the beneficial effects of exposure to mild hyperbaric oxygen on some metabolic diseases and their perspectives.

Restoration of skin pigmentation after deep partial or full-thickness burn injury

Significant skin pigmentation changes occur when patients suffer deep burn injuries. These pigmentation disorders may cause not only cosmetic and psychological issues, but more importantly it increases the risk of skin cancer or photoaging. Severe burns significantly effect on the process of repigmentation as the pigmentation is tightly regulated by cell proliferation and differentiation of melanocytes and melanocyte stem cells which are housing in the epidermis and hair follicles of the skin. In the present review, we discuss the possible mechanisms to replenish the melanocytes from the healthy epidermis and hair follicles surrounding burn wounds. The molecular mechanisms of skin repigmentation following healing of burn injuries includes the differentiation of melanoblasts into melanocytes, the distribution and responses of melanocytes and melanocyte stem cells after burn injury, and the regulation of melanin production. We also reviewed advanced therapeutic strategies to treat pigmentation disorders, such as convectional surgery, laser, UV treatment and emerging concepts in skin tissue-engineering.

Mild Hyperbaric Oxygen Inhibits Growth-related Decrease in Muscle Oxidative Capacity of Rats with Metabolic Syndrome

Aim: We examined the effects of mild hyperbaric oxygen on the properties of the soleus muscle in rats with metabolic syndrome.

Methods: Five-week-old metabolic syndrome (SHR/NDmcr-cp, cp/cp) rats were divided into normobaric (CP) and mild hyperbaric oxygen (CP-H) groups (n = 5/group). In addition, 5-week-old Wistar rats were assigned as the normobaric control (WR) group (n = 5). The CP-H group was exposed to 1.25 atmospheres absolute with 36% oxygen for 3 h daily for 16 weeks. Succinate dehydrogenase (SDH) activity and mRNA levels of peroxisome proliferator-activated receptor γ coactivator-1α (Pgc-1α) in the soleus muscle were examined. The fiber type composition, cross-sectional areas, and SDH staining intensity in the soleus muscle were also examined.

Results: The CP-H group showed lower fasting and nonfasting blood glucose, glycated hemoglobin, total cholesterol, triglyceride, insulin, and systolic blood pressure levels; higher adiponectin levels; and higher SDH activity and mRNA levels of Pgc-1α in the muscle than the CP group. Compared with the CP group, the CP-H group had a lower percentage of type I fibers and observed type IIA fibers in the muscle. The CP-H group also had higher SDH staining intensity of type I and type IIC fibers in the muscle than the CP group. No differences in these values were observed in the muscles of the WR and CP-H groups.

Conclusion: Mild hyperbaric oxygen inhibited growth-related increase in blood glucose levels and decrease in muscle oxidative capacity of rats with metabolic syndrome because of improved oxidative metabolism.

Mild Hyperbaric Oxygen Improves Decreased Oxidative Capacity of Spinal Motoneurons Innervating the Soleus Muscle of Rats with Type 2 Diabetes

Rats with type 2 diabetes exhibit decreased oxidative capacity, such as reduced oxidative enzyme activity, low-intensity staining for oxidative enzymes in fibers, and no high-oxidative type IIA fibers, in the skeletal muscle, especially in the soleus muscle. In contrast, there are no data available concerning the oxidative capacity of spinal motoneurons innervating skeletal muscle of rats with type 2 diabetes. This study examined the oxidative capacity of motoneurons innervating the soleus muscle of non-obese rats with type 2 diabetes. In addition, this study examined the effects of mild hyperbaric oxygen at 1.25 atmospheres absolute with 36 % oxygen for 10 weeks on the oxidative capacity of motoneurons innervating the soleus muscle because mild hyperbaric oxygen improves the decreased oxidative capacity of the soleus muscle in non-obese rats with type 2 diabetes. Spinal motoneurons innervating the soleus muscle were identified using nuclear yellow, a retrograde fluorescent neuronal tracer. Thereafter, the cell body sizes and succinate dehydrogenase activity of identified motoneurons were analyzed. Decreased succinate dehydrogenase activity of small-sized alpha motoneurons innervating the soleus muscle was observed in rats with type 2 diabetes. The decreased succinate dehydrogenase activity of these motoneurons was improved by mild hyperbaric oxygen. Therefore, we concluded that rats with type 2 diabetes have decreased oxidative capacity in motoneurons innervating the soleus muscle and this decreased oxidative capacity is improved by mild hyperbaric oxygen.

Sequential release of salidroside and paeonol from a nanosphere-hydrogel system inhibits ultraviolet B-induced melanogenesis in guinea pig skin

Melanin is the one of most important pigments for skin color in mammals. Excessive biosynthesis of melanin induces various pigment disorders. Much effort has been made to develop regulators to minimize skin pigmentation abnormalities. However, only a few of them are used, primarily because of safety concerns and low efficiency. In this study, we aimed to construct a novel nanosphere-gel for sequential delivery of salidroside and paeonol, to investigate the synergistic effects of these drugs in anti-melanogenesis, and to decrease their potential for toxicity in high dosage. Nanospheres were prepared and characterized for their particle size, polydispersity index, zeta potential, and morphological properties. The optimized nanospheres were incorporated in carbomer hydrogel with both paeonol and salidroside entrapped to form a dual drug-releasing nanosphere-gel. With this nanosphere-gel, rapid release of salidroside from the hydrogel followed by sustained release of paeonol from the nanosphere was achieved. Using a classical model of the melanogenesis response to ultraviolet exposure, it was shown that the anti-melanogenesis effects of the dual drug-releasing system, in which the doses of the individual drugs were decreased by half, was obviously enhanced when compared with the effects of the single drug preparations. Mechanistically, the burst release of salidroside from the hydrogel may enable prompt suppression of melanocyte proliferation on exposure to ultraviolet B radiation, while the paeonol released in a sustained manner can provide continuous inhibition of tyrosinase activity in melanocytes. Combined delivery of salidroside and paeonol was demonstrated to be a promising strategy for enhancing the therapeutic efficacy of these agents in anti-melanogenesis and reducing their toxicity, so may have great potential in nanomedicine.