Species pool, local assembly processes: Disentangling the mechanisms determining bacterial α- and ß-diversity during forest secondary succession.

Across ecology, and particularly within microbial ecology, there is limited understanding how the generation and maintenance of diversity. Although recent work has shown that both local assembly processes and species pools are important in structuring microbial communities, the relative contributions of these mechanisms remain an important question. Moreover, the roles of local assembly processes and species pools are drastically different when explicitly considering the potential for saturation or unsaturation, yet this issue is rarely addressed. Thus, we established a conceptual model that incorporated saturation theory into the microbiological domain to advance the understanding of mechanisms controlling soil bacterial diversity during forest secondary succession. Conceptual model hypotheses were tested by coupling soil bacterial diversity, local assembly processes and species pools using six different forest successional chronosequences distributed across multiple climate zones. Consistent with the unsaturated case proposed in our conceptual framework, we found that species pool consistently affected α-diversity, even while local assembly processes on local richness operate. In contrast, the effects of species pool on ß-diversity disappeared once local assembly processes were taken into account, and changes in environmental conditions during secondary succession led to shifts in ß-diversity through mediation of the strength of heterogeneous selection. Overall, this study represents one of the first to demonstrate that most local bacterial communities might be unsaturated, where the effect of species pool on α-diversity is robust to the consideration of multiple environmental influences, but ß-diversity is constrained by environmental selection.

Comparative Study of the Morphological Characteristics of Perforators of the Transverse and Descending Branches of the Lateral Circumflex Femoral Artery in Anterolateral Thigh Flap Surgery.

BACKGROUND: The anterolateral thigh flap (ALTF) is a kind of lateral thigh flap that uses branches of the lateral circumflex femoral artery (LCFA) as the vessel pedicle and is widely used in plastic surgery. During classic ALTF surgery, some perforators from the descending branch of the lateral circumflex femoral artery (LCFA-db) are hard to harvest due to their anatomical variants and individual differences; thus, it is necessary to design an appropriate alternative surgical plan. The transverse branch of the LCFA (LCFA-tb) has unique advantages and can be a potential complement to ALTF vascular pedicle selection. The aim of this study was to compare the difference in morphology between LCFA-db and LCFA-tb, and to verify the feasibility and clinical effect of ALTF with LCFA-tb as the source artery. METHODS: The morphological and clinical data of patients who underwent wound repair of the extremities with the ALTF pedicled with the LCFA-tb and LCFA-db were retrospectively analyzed. This study consisted of the clinical data of 62 patients who accepted an ALTF pedicled with LCFA-tb, and 45 patients accepted an ALTF pedicled with LCFA-db. RESULTS: A total of 68 cutaneous perforators originating from the LCFA-tb were found in the surgical field, of which 35 perforators were direct cutaneous perforators (51.5%), 28 perforators were septocutaneous perforators (41.2%), and 5 perforators were musculocutaneous perforators (7.3%). Seventy-four cutaneous perforators were found in the LCFA-db group. The proportions of septocutaneous perforators and musculocutaneous perforators were 23% and 77%, respectively, and the number of direct cutaneous perforators was 0. The harvest time of flaps pedicled with LCFA-tb was remarkably shortened. Regarding prognosis, there were no significant differences between the curative effects of the 2 types of flaps. CONCLUSIONS: This study verified that most LCFA-tb perforators are direct cutaneous perforators and that the piercing-in positions of LCFA-tb perforators on superficial fascia were higher than those of LCFA-db perforators. Furthermore, the ALTF pedicled with LCFA-tb can provide satisfactory soft tissue reconstruction and can be used as a useful supplement to the traditional flap design.

Self-pulsing and dual-mode lasing in a square microcavity semiconductor laser.

Self-pulsing and dual-mode lasing in a square microcavity semiconductor laser are studied experimentally. Self-sustained pulses originating from undamped relaxation oscillation induced by a two-mode interaction are obtained, as the injection current is slightly above the laser threshold. A repetition frequency of 4.4 GHz and a pulse width of 30-40 ps are obtained at a current of 8 mA. The laser switches to continuous-wave operation when the injection current is higher than a certain value, and dual-mode lasing with 30.7 GHz at 16 mA and 10.7 GHz at 27 mA are observed in the lasing spectra. Furthermore, the relative intensity noise spectra are presented to reveal the relationship between the lasing states and the dynamics induced by relaxation oscillation and mode beating.

Experimental demonstration of pseudo-pilots-aided Gaussian basis expansion-based phase noise suppression scheme for CO-OFDM.

In this paper, we propose a novel phase noise suppression scheme called pseudo-pilots-aided Gaussian basis expansion (PS-GBE) for coherent optical orthogonal frequency division multiplexing (CO-OFDM) system. Integrating with the pseudo-pilots, the Gaussian basis can suppress and fit phase noise effectively with high spectral efficiency (SE). We experimentally demonstrate the proposed scheme in 200-Gb/s optical QPSK-OFDM superchannel and 400-Gb/s optical 16QAM-OFDM superchannel. According to the experimental results, the proposed PS-GBE has a phase noise suppression performance similar to the GBE scheme. However, different from the GBE scheme, fewer pilots are needed for phase noise estimation in PS-GBE. Hence, the proposed PS-GBE can achieve higher SE. Compared to the pseudo-pilots-aided orthogonal basis expansion-based (PS-OBE) phase noise suppression and traditional common phase noise compensation (CPEC) methods, the proposed PS-GBE can get a significant performance enhancement. In the QPSK-OFDM system, a Q-factor improvement of 1.1 dB is obtained compared to the PS-OBE method. In the 16QAM-OFDM system, the BER is enhanced from 1.00E-03 to 2.05E-04. Further simulation results indicate that our proposed PS-GBE scheme can effectively increase laser linewidth tolerance. The proposed scheme can be applied to CO-OFDM and extended to coherent optical filterbank multicarrier (CO-FBMC) and coherent optical single carrier frequency domain multiplexing (CO-SCFDM) transmission system.

Multi scrolls chaotic encryption scheme for CO-OFDM-PON.

In this paper, we propose and experimentally demonstrate a novel multi scrolls chaotic encryption scheme for CO-OFDM-PON. We analyze the principle of 3-dimension encryption scheme and discuss its encryption complexity. Compared with the previous hyper Chen chaotic encryption scheme, the proposed encryption algorithm can realize dynamic constellation point mapping of QAM signal with lower encryption complexity. We also compare the transmission performances of the two chaotic encryption schemes. The results show that the proposed multi scrolls scheme has better BER performance because it can decrease the peak to average power ratio (PAPR) of OFDM. What is more, the proposed encryption scheme is very sensitive to the initial secure key and a tiny discrepancy as small as 10-17 would lead to a completely different sequence. The high sensibility to the initial value can effectively increase encryption level and the key space of the multi scrolls encryption scheme is 106 times of that hyper Chen. Further, to verify the effectiveness of the proposed encryption algorithm, encrypted transmission of a digital picture in 80 km SSMF is carried out.

Gaussian basis expansion phase noise suppression method for CO-OFDM systems.

In this paper, we propose a novel phase noise suppression method based on Gaussian basis expansion (GBE) for CO-OFDM systems. We analyze the basic phase noise suppression principle of GBE and then demonstrate it in optical OFDM transmission systems. Compared with common phase compensation (CPE), orthogonal basis expansion (OBE) and eigenvector basis expansion (EBE) schemes, the proposed GBE scheme has better phase noise fitting ability with similar computation complexity. Futhermore, no additional back to back (BTB) pre-training is needed for the GBE scheme. Performance improvements by the GBE is experimental validated in the QPSK/16-QAM OFDM system with different transmission scenarios (different number of pilots and input power). In the QPSK-OFDM system, after 160 km SSMF transmission, a Q-factor improvement of 1.7 dB and 0.5 dB are achieved compared with the CPE and OBE schemes at the optimum input power of -4 dBm, respectively. In the 16-QAM-OFDM system, the measured BER improved from 8.21×10-4 to 2.36×10-4 with the GBE scheme. To further verify the effectiveness of the GBE scheme, we change the laser linewidth and measure the long transmission distance performance by simulation, the results show that the GBE scheme can effectively increase the laser linewidth tolerance and extend transmission distance. When the linewidth is 2-MHz, the proposed GBE scheme can extend the transmission distance from 1120 km to 1540 km at the BER of 10-4. Experimental and simulation results show that the proposed GBE scheme is a promising alternative phase noise suppression for CO-OFDM system.

Wideband frequency-tunable optoelectronic oscillator with a directly modulated AlGaInAs/InP integrated twin-square microlaser.

We propose and demonstrate an optoelectronic oscillator with a directly modulated AlGaInAs/InP integrated twin-square microlaser for generating wideband frequency-tunable microwave signals with low phase noise. Apart from the relaxation oscillation peak, the modulation response of the twin-square microlaser working at the mutual optical injection state exhibits a significant enhancement around the beating frequency of the lasing modes in the two square cavities owing to the photon-photon resonance. A self-sustaining oscillation can be generated around the modulation response peak with the lowest loop loss occurring at the relaxation oscillation frequency or the beating frequency, depending on the practical state of the twin-square microlaser. High-quality tunable microwave signals ranging from 2.22 to 19.52 GHz are generated with single sideband phase noises below -110 dBc/Hz at the 10 kHz offset frequency and side-mode suppression ratios of approximately 40 dB by tuning the injection currents of the twin-square microlaser.

A dataset of the daily edge of each polynya in the Antarctic.

Polynyas play a critical role in the formation of Antarctic Bottom Water and the enhancement of polar primary productivity. Accurate and exhaustive identification of Antarctic polynyas is fundamental to advancing in-depth research. However, due to methodological limitations, previous studies paid more attention to frequent polynyas and infrequent polynyas have not been investigated much despite that they could be vulnerable to climate change. Inspired by a cyclone tracking algorithm, we develop a novel method to overcome challenges identifying all types of polynyas satisfying spatiotemporal criteria and tracing their daily evolution, extracting from an extensive amount of sea ice concentration data. Based on it, we establish a dataset called "Daily Edge of Each Polynya in Antarctica" (DEEP-AA). Validation against remote sensing and ship-based observations confirms DEEP-AA's reliability. Compared to existing maps, the DEEP-AA identifies a threefold number of polynyas and reveals the seasonal area recovery of infrequent polynyas is earlier than frequent ones.

Endothelial transferrin receptor 1 contributes to thrombogenesis through cascade ferroptosis.

Oxidative stress and iron accumulation-induced ferroptosis occurs in injured vascular cells and can promote thrombogenesis. Transferrin receptor 1 (encoded by the TFRC gene) is an initial element involved in iron transport and ferroptosis and is highly expressed in injured vascular tissues, but its role in thrombosis has not been determined. To explore the potential mechanism and therapeutic effect of TFRC on thrombogenesis, a DVT model of femoral veins (FVs) was established in rats, and weighted correlation network analysis (WGCNA) was used to identify TFRC as a hub protein that is associated with thrombus formation. TFRC was knocked down by adeno-associated virus (AAV) or lentivirus transduction in FVs or human umbilical vein endothelial cells (HUVECs), respectively. Thrombus characteristics and ferroptosis biomarkers were evaluated. Colocalization analysis, molecular docking and coimmunoprecipitation (co-IP) were used to evaluate protein interactions. Tissue-specific TFRC knockdown alleviated iron overload and redox stress, thereby preventing ferroptosis in injured FVs. Loss of TFRC in injured veins could alleviate thrombogenesis, reduce thrombus size and attenuate hypercoagulability. The protein level of thrombospondin-1 (THBS1) was increased in DVT tissues, and silencing TFRC decreased the protein level of THBS1. In vitro experiments further showed that TFRC and THBS1 were sensitive to erastin-induced ferroptosis and that TFRC knockdown reversed this effect. TFRC can interact with THBS1 in the domain spanning from TSR1-2 to TSR1-3 of THBS1. Amino acid sites, including GLN320 of TFRC and ASP502 of THBS1, could be potential pharmacological targets. Erastin induced ferroptosis affected extracellular THBS1 levels and weakened the interaction between TFRC and THBS1 both in vivo and in vitro, and promoted the interaction between THBS1 and CD47. This study revealed a linked relationship between venous ferroptosis and coagulation cascades. Controlling TFRC and ferroptosis in endothelial cells can be an efficient approach for preventing and treating thrombogenesis.

Is the oblique branch of the lateral circumflex femoral artery a common variant?

The oblique branch of the lateral circumflex femoral artery, a short branch of the deep femoral artery, is highly prevalent (32-46%) and is usually considered a normal variant, although this is still controversial. This study aimed to evaluate whether the oblique branch of the lateral circumflex femoral artery is a variant. We reviewed medical record data of patients with skin and soft tissue defects of the extremities who underwent flap repair using free anterolateral thigh (ALT) flaps at our hospital in 2019. The anatomical characteristics of the flaps were examined intraoperatively by high-frequency color Doppler ultrasound. A total of 153 ALT flaps from 146 patients were included. Among the branches, 232 (73.7%) were oblique branches, and 83 (26.4%) were descending branches. Of the 232 oblique branches, 141 (60.8%) were from septocutaneous branches, and the other 83 (39.2%) were from musculocutaneous branches. In addition, 20 (24.1%) descending branches were from septocutaneous branches, and the other 63 (75.9%) were from musculocutaneous branches. Analyzing the prevalence of the oblique branch in septocutaneous branches, more than half of the patients had oblique branches rather than descending branches. The high proportion of oblique branches from septocutaneous branches (median: 100 (0-100) vs. 0 (0-50), p = 0.002) supports the understanding that the oblique branch is a normal anatomical element rather than a variant. The main type was the intramuscular branches, which required significantly less time for flap harvesting. The oblique branch may be the preferred vascular pedicle for free ALT flaps.

Reconstruction of large-area wounds in limbs using two flow-through anterolateral thigh perforator flaps.

INTRODUCTION: Limb salvage in large wounds is difficult because the disrupted blood supply does not support a flap. This study evaluated the clinical efficacy of using two flow-through anterolateral thigh perforator flaps for reconstructing large-area limb wounds. METHODS: This retrospective study included 45 patients who underwent reconstruction of large limb wounds using two flow-through anterolateral thigh perforator flaps at Ruihua Hospital between January 2015 and December 2020. Wound areas ranged from 15 cm × 13 cm to 46 cm × 18 cm. Single flap areas ranged from 16 cm × 8 cm to 46 cm × 9 cm. Blood supply locations were identified using color Doppler ultrasound or digital subtraction angiography (DSA) images. Primary outcomes were flap survival and complications at recipient or donor sites during at least 6-months follow-up. RESULTS: The overall flap survival rate was 97% (87/90). All donor sites healed by first intention. Three cases developed vascular crises, which were alleviated by reoperation. One case had flexor contracture in left toes, relieved by cutting flexor tendons; 13 cases had flap bloat, relieved by flap thinning at 6 months. All cases showed properly healed wounds and functional reconstruction. CONCLUSIONS: Reconstruction of large-area limb wounds using two flow-through anterolateral thigh perforator flaps provides safe and satisfactory effects without donor-site morbidity, and with proper healing and restored function.

High performance of CH3NH3PbCl3 perovskite single crystal photodetector with a large active area using asymmetrical Schottky interdigital contacts.

Due to the limited electrode structure types of current CH3NH3PbCl3 perovskite single crystal photodetectors, these devices either have good performance but small active area or have large active area but poor performance, which greatly limits their applications. To realize a high performance of a CH3NH3PbCl3 perovskite single crystal photodetector with a large active area, a CH3NH3PbCl3 single crystal photodetector with asymmetrical Schottky interdigital contacts originating from planar interdigital Au-Ag electrodes was fabricated in this work. The device not only had a large active area (around 8 mm2) but also showed excellent photoelectric performance due to its built-in electric field. The responsivity of the device can reach 5.8 mA W-1 at 0 V and 0.24 A W-1 at 30 V reverse voltage. The response time of the device can reach 317 µs (rise)/6.82 ms (decay) at 0 V and 100 µs (rise)/2 ms (decay) at 30 V reverse voltage. The above results demonstrate that this study will provide an effective method for realizing high performance of a CH3NH3PbCl3 perovskite single crystal photodetector with a large active area.

[Clinical application of anterolateral thigh perforator flap pedicled with oblique branch in intramuscular of lateral circumflex femoral artery].

Objective: To explore the characteristics and clinical application of the anterolateral thigh flap pedicled with the oblique branch in the intramuscular of lateral circumflex femoral artery. Methods: The clinical data of 25 patients with skin and soft tissue defects of extremities admitted between December 2020 and April 2021 were retrospectively analyzed, including 16 males and 9 females, aged 14-75 years, with the median age of 43 years. The defect site included 13 cases of hand, 2 cases of forearm, 2 cases of calf, and 8 cases of foot and ankle. The wound area ranged from 6 cm×4 cm to 35 cm×22 cm. Twenty-four patients with trauma were admitted to hospital immediately after injury, and 1 patient with diabetic foot infection was transferred to the hospital after ineffective treatment in other hospital. Flap surgery was performed from 0 to 56 days (median, 22 days) after admission. A total of 26 thigh flaps were harvested in 25 patients, with unilateral flaps in size of 7 cm×5 cm to 40 cm×10 cm. The type, caliber, and location of the perforating branch were recorded during the operation, and the anatomical characteristics of the oblique branch of the intramuscular trunk were mainly observed. The flap harvesting time was recorded; the flap survival and wound healing time were observed; at last follow-up, XIAO Feipeng et al. flap comprehensive efficacy evaluation table was used to evaluate the effectiveness of flap repair from three aspects of donor site, recipient site, and subjective satisfaction of doctors and patients. Results: After the oblique branch in intramuscular of lateral circumflex femoral artery was sent out, it ran 2-3 cm obliquely laterally and inferiorly in the intermuscular septum and then entered the vastus lateralis muscle, and sent out perforating branches to nourish the skin. A total of 61 perforating branches were marked in 26 thighs of 25 patients before operation, and 70 perforating branches were found during operation, including 9 transverse branches, 29 descending branches, and 32 oblique branches, all of the oblique branches were musculocutaneous perforators. All 25 patients were followed up 6-10 months, with an average of 8 months. The time of unilateral thigh flap harvesting ranged from 13 to 90 minutes, with an average of 48 minutes. One patient with diabetes developed disturbance of blood supply and complete necrosis of the flap at 1 month after operation, and then the flap was repaired with skin graft; 1 case developed arterial crisis after operation, which survived after timely exploration; and the rest of the flaps survived smoothly. The wound healing time of the recipient site ranged from 10 to 44 days, with an average of 19 days, and the donor site of the thigh healed by first intention. At last follow-up, the color and texture of the flap was good and the sensation recovered to S 1-S 2. Only linear scar was left in the donor site, no scar contracture, pain, and other discomfort occurred, and no other serious complications occurred. Evaluated by flap comprehensive efficacy evaluation table, the score was 74-93, with an average of 88, of which 10 cases were excellent, 13 cases were good, and 2 cases were fair, with an excellent and good rate of 92%. Conclusion: The intramuscular trunk oblique branch is not uncommon, and its trunk course and perforators distribution are regular. To improve the understanding of this type of oblique branch and adopt appropriate methods during operation can improve the success rate of skin flap extraction.

Local community assembly mechanisms shape soil bacterial ß diversity patterns along a latitudinal gradient.

Biodiversity patterns across geographical gradients could result from regional species pool and local community assembly mechanisms. However, little has been done to separate the effects of local ecological mechanisms from variation in the regional species pools on bacterial diversity patterns. In this study, we compare assembly mechanisms of soil bacterial communities in 660 plots from 11 regions along a latitudinal gradient in eastern China with highly divergent species pools. Our results show that ß diversity does not co-vary with γ diversity, and local community assembly mechanisms appear to explain variation in ß diversity patterns after correcting for variation in regional species pools. The variation in environmental conditions along the latitudinal gradient accounts for the variation in ß diversity through mediating the strength of heterogeneous selection. In conclusion, our study clearly illustrates the importance of local community assembly processes in shaping geographical patterns of soil bacterial ß diversity.

Functional recovery of a subtropical evergreen-deciduous broadleaved mixed forest following clear cutting in central China.

Ecosystem functioning is largely dependent on the functional traits of its component species. Most of the previous researches on ecosystem recovery have mainly focused on taxonomic composition but less attention is concentrated on functional community composition. Here, we examine the dynamic trend of functional community composition along a recovery chronosequence following clear cutting in subtropical evergreen-deciduous broadleaved mixed forest. Results showed that with the process of recovery, the functional composition changed from a community with high specific leaf area (CWM_ SLA), leaf nitrogen concentration (CWM_ LNC) and leaf phosphorus (CWM_ LPC) but low leaf thickness (CWM_ LT) and stem tissue density (CWM_ STD) to that with low CWM_ SLA, CWM_ LNC and CWM_ LPC but high CWM_ LT and CWM_ STD. Functional traits of evergreen and deciduous species were significantly different in each stage. Light availability and soil phosphorus were the most important influencing factors during the recovery. Our study suggests that the subtropical evergreen-deciduous broadleaved mixed forest is gradually shifting from a resource acquisitive to a resource conservative assemblage, in which evergreen species will become more and more dominant. Any management or conservation planning upon the forest ecosystem should integrate this dynamic trend of functional change.

[Efficacy of two bariatric surgeries in type 2 diabetic patients with a body mass index of 25-27.5].

OBJECTIVE: To evaluate the therapeutic effects of laparoscopic Roux-en-Y gastric bypass (LRYGB) and laparoscopic duodenal-jejunal bypass with sleeve gastrectomy (SADJB-SG) in patients with type 2 diabetes mellitus and a low body mass index (BMI) of 25-27.5. METHODS: Thirty-one type 2 diabetic patients with a BMI of 25-27.5 underwent bariatric surgeries in the General Hospital of Guangzhou Military Command between August, 2013 and August, 2015. The patients receiving LRYGB (17 cases) and SADJB-SG (14 cases) were compared for physical indexes, glucose metabolism and of pancreatic islet function at 1 year after the surgeries. RESULTS: No mortality occurred in the patients after the operations. At 1 year after the operation, the patients in LRYGB group showed significant improvements in body weight, BMI, glycated hemoglobin (HbA1c), fasting plasma glucose (FPG), oral glucose tolerance test 2 h (OGTT2h), C-peptide, fasting insulin (FINS), and postprandial 2 hour insulin (2 hPINS) (P<0.05); in SADJB-SG group, significant improvements were observed in the body weigh, BMI, HbA1c, FPG, OGTT2h, and FINS after the operation (P<0.05). The postoperative improvements in body weigh, BMI, HbA1c, FPG, OGTT2h, C-peptide, and 2hPINS were comparable between SADJB-SG group and LRYGB group (P>0.05), but the incidence of postoperative anastomotic ulcer was lower in SADJB-SG group. CONCLUSION: SADJB-SG and LRYGB produce similar therapeutic effects in type 2 diabetic patients with a low BMI, but SADJB-SG is associated with a low incidence of postoperative complications and is therefore more suitable in such patients.

Changes of soil prokaryotic communities after clear-cutting in a karst forest: evidences for cutting-based disturbance promoting deterministic processes.

To understand the temporal responses of soil prokaryotic communities to clear-cutting disturbance, we examined the changes in soil bacterial and archaeal community composition, structure and diversity along a chronosequence of forest successional restoration using high-throughput 16S rRNA gene sequencing. Our results demonstrated that clear-cutting significantly altered soil bacterial community structure, while no significant shifts of soil archaeal communities were observed. The hypothesis that soil bacterial communities would become similar to those of surrounding intact primary forest with natural regeneration was supported by the shifts in the bacterial community composition and structure. Bacterial community diversity patterns induced by clear-cutting were consistent with the intermediate disturbance hypothesis. Dynamics of bacterial communities was mostly driven by soil properties, which collectively explained more than 70% of the variation in bacterial community composition. Community assembly data revealed that clear-cutting promoted the importance of the deterministic processes in shaping bacterial communities, coinciding with the resultant low resource environments. But assembly processes in the secondary forest returned a similar level compared to the intact primary forest. These findings suggest that bacterial community dynamics may be predictable during the natural recovery process.

Inhaled budesonide and oral dexamethasone prevent acute mountain sickness.

BACKGROUND: This double-blind, randomized controlled trial aimed to investigate inhaled budesonide and oral dexamethasone compared with placebo for their prophylactic efficacy against acute mountain sickness after acute high-altitude exposure. METHODS: There were 138 healthy young male lowland residents recruited and randomly assigned to receive inhaled budesonide (200 µg, twice a day [bid]), oral dexamethasone (4 mg, bid), or placebo (46 in each group). They traveled to 3900 m altitude from 400 m by car. Medication started 1 day before high-altitude exposure and continued until the third day of exposure. Primary outcome measure was the incidence of acute mountain sickness after exposure. RESULTS: One hundred twenty-four subjects completed the study (42, 39, and 43 in the budesonide, dexamethasone, and placebo groups, respectively). Demographic characteristics were comparable among the 3 groups. After high-altitude exposure, significantly fewer participants in the budesonide (23.81%) and dexamethasone (30.77%) groups developed acute mountain sickness compared with participants receiving placebo (60.46%) (P = .0006 and P = .0071, respectively). Both the budesonide and dexamethasone groups had lower heart rate and higher pulse oxygen saturation (SpO2) than the placebo group at altitude. Only the budesonide group demonstrated less deterioration in forced vital capacity and sleep quality than the placebo group. Four subjects in the dexamethasone group reported adverse reactions. CONCLUSIONS: Both inhaled budesonide (200 µg, bid) and oral dexamethasone (4 mg, bid) were effective for the prevention of acute mountain sickness, especially its severe form, compared with placebo. Budesonide caused fewer adverse reactions than dexamethasone.