Protection of laryngeal mucosa and function in laryngeal burns by heat absorption of perilaryngeal tissue.

OBJECTIVE: The laryngeal tissue carries most of the heat during inhalation injury. This study aims to explore the heat transfer process and the severity of injury inside laryngeal tissue by horizontally studying the temperature rise process at various anatomical layers of the larynx and observing the thermal damage in various parts of the upper respiratory tract. METHODS: The 12 healthy adult beagles were randomly divided into four groups, and inhaled room temperature air (control group), dry hot air of 80 °C (group I), 160 °C (group II), and 320 °C (group III) for 20 min, respectively. The temperature changes of the glottic mucosal surface, the inner surface of the thyroid cartilage, the external surface of the thyroid cartilage, and subcutaneous tissue were measured every minute. All animals were immediately sacrificed after injury, and pathological changes in various parts of laryngeal tissue were observed and evaluated under a microscope. RESULTS: After inhaling hot air of 80 °C, 160 °C and 320 °C, the increase of laryngeal temperature in each group was ΔT = 3.57 ± 0.25 °C, 7.83 ± 0.15 °C, 11.93 ± 0.21 °C. The tissue temperature was approximately uniformly distributed, and the difference was not statistically significant. The average laryngeal temperature-time curve showed that the laryngeal tissue temperature in group I and group II showed a trend of "first decrease and then increase", except that the temperature of group III directly increased with time. The prominent pathological changes after thermal burns mainly concluded necrosis of epithelial cells, loss of the mucosal layer, atrophy of submucosal glands, vasodilatation, erythrocytes exudation, and degeneration of chondrocytes. Mild degeneration of cartilage and muscle layers was also observed in mild thermal injury. Pathological scores indicated that the pathological severity of laryngeal burns increased significantly with the increase of temperature, and all layers of laryngeal tissue were seriously damaged by 320 °C hot air. CONCLUSIONS: The high efficiency of tissue heat conduction enabled the larynx to quickly transfer heat to the laryngeal periphery, and the heat-bearing capacity of perilaryngeal tissue has a certain degree of protective effect on laryngeal mucosa and function in mild to moderate inhalation injury. The laryngeal temperature distribution was in accordance with the pathological severity, and the pathological changes of laryngeal burns provided a theoretical basis for the early clinical manifestations and treatment of inhalation injury.

Epigenetic regulation of ferroptosis by H2B monoubiquitination and p53.

Monoubiquitination of histone H2B on lysine 120 (H2Bub1) is an epigenetic mark generally associated with transcriptional activation, yet the global functions of H2Bub1 remain poorly understood. Ferroptosis is a form of non-apoptotic cell death characterized by the iron-dependent overproduction of lipid hydroperoxides, which can be inhibited by the antioxidant activity of the solute carrier family member 11 (SLC7A11/xCT), a component of the cystine/glutamate antiporter. Whether nuclear events participate in the regulation of ferroptosis is largely unknown. Here, we show that the levels of H2Bub1 are decreased during erastin-induced ferroptosis and that loss of H2Bub1 increases the cellular sensitivity to ferroptosis. H2Bub1 epigenetically activates the expression of SLC7A11. Additionally, we show that the tumor suppressor p53 negatively regulates H2Bub1 levels independently of p53's transcription factor activity by promoting the nuclear translocation of the deubiquitinase USP7. Moreover, our studies reveal that p53 decreases H2Bub1 occupancy on the SLC7A11 gene regulatory region and represses the expression of SLC7A11 during erastin treatment. These data not only suggest a noncanonical role of p53 in chromatin regulation but also link p53 to ferroptosis via an H2Bub1-mediated epigenetic pathway. Overall, our work uncovers a previously unappreciated epigenetic mechanism for the regulation of ferroptosis.

[Pathological changes in different parts of the larynx in canines following laryngeal burns induced by inhalation of hot air at various temperatures].

OBJECTIVE: To examine pathological changes in different parts of the larynx in canines after laryngeal burns induced by hot dry air at various temperatures and compare the pathological results with clinical typing. METHODS: Eighteen healthy, male, adult dogs were randomly assigned to inhale hot dry air at 80 °C (Group 1), 160 °C (Group 2) or 320 °C (Group 3) for 20 min to induce inhalation injury. Pathological changes after hot air inhalation were examined at different locations of the larynx including the epiglottis, laryngeal vestibule, vocal folds and trachea. RESULTS: Pathological changes were mainly characterized by local mucosal atrophy in the larynx in Group 1 and moderate edema in the laryngeal submucosa in Group 2. Group 3 showed two types of pathological changes in the larynx: severe edema as well as atrophy and charring. CONCLUSION: Due to its special anatomy and functions, the larynx has different responses to inhalation injuries induced by hot air at different temperatures. The pathological observation and analysis showed that the pathological changes brought about by laryngeal burns at 80 °C and 160 °C were generally consistent with laryngoscopic manifestations of congestion and edema. Inhalation of hot dry air at 320 °C led to two types of pathological changes, severe edema and atrophy and charring. Hence, pathological analysis of laryngeal burns may be used as a supplemental tool to clinical typing.

Epidemiology and risk prediction of patients with severe burns admitted to a burn intensive care unit in a burn center in beijing: A 5-year retrospective study.

Objective: This study was performed to describe the epidemiology of patients with severe burns hospitalized in a burn intensive care unit (BICU), explore the risk factors associated with the patients' outcomes and evaluate the ability of prognostic scoring systems as risk prediction of mortality. Methods: The data for this study were derived from patients with severe burns in the BICU of Beijing Jishuitan Hospital from 2015 to 2019. The following epidemiological information and outcomes were collected for retrospective analysis: sex, age, date of injury, etiology of burn, admission time after injury, extent of burn, inhalation injury, length of stay, and outcome. Abbreviated Burn Severity Index (ABSI), prognostic burn index (PBI), the burn index (BI), Belgian Outcome in Burn Injury (BOBI) scores and the revised Baux (rBaux) scores were calculated. Results: Of the 243 patients included in this study, the median age was 41.00 (22.00) years and the male: female ratio was 4.28:1.00. Most of the burns had occurred from March to July. Flame was the main cause of the burns (77.37%), followed by electricity (14.40%). In total, 78.19% of all patients sustained third-degree burns, and the median burn area and third-degree burn area of patients were 40% (53%) and 15.0% (43.0%) of the total body surface area, respectively. The incidence of inhalation injury was 69.14%. Tracheotomy was performed in 53.89% of the patients with inhalation injuries, and the rate of tracheostomy showing a rising trend. The median length of stay was 37 (40) days, and the case fatality rate was 8.64%. Multivariable logistic regression model indicated that age and third-degree burn area were risk factors for death, and the area under the receiver operating characteristic curve for the full prediction model was 0.921 (95% CI = 0.874-0.967). Conclusions: The majority of severe burns are flame-related accidents in middle-aged men. Risk prediction model combining age and third-degree burn area has better mortality predictive value.

The nucleolus functions as the compartment for histone H2B protein degradation.

Histones are main components of chromatin, and the protein levels of histones significantly affect chromatin assembly. However, how histone protein levels are regulated, especially whether and how histones are degraded, is largely unclear. Here, we found that histone H2B is mainly degraded through the proteasome-mediated pathway, and the lysine-120 site of H2B is essential for its K48-linked polyubiquitination and degradation. Moreover, the degradation-impaired H2BK120R mutant shows an increased nucleolus localization, and inhibition of the proteasome results in an elevated nucleolus distribution of wild-type H2B, which is similar to that of H2BK120R mutants. More importantly, the nucleolus fractions can ubiquitinate and degrade the purified H2B in vitro, suggesting that the nucleolus, in addition to its canonical roles regulating ribosome genesis and protein translation, likely associates with H2B degradation. Therefore, these findings revealed a novel mechanism for the regulation of H2B degradation in which a nucleolus-associated proteasome pathway is involved.

[Pathogenic bacteria distribution and drug resistance analysis in burns department].

OBJECTIVE: To study the distribution and drug resistance of pathogenic bacterium and find the proper measures of infection control. METHODS: Six hundred and eighty-two pathogenic bacteria strains were isolated and cultured from samples collected from January 2003 to December 2005. The pathogenic bacterium distribution and antibiotic resistance were analyzed. RESULTS: The detection rate of gram-negative bacteria was higher than gram-positive ones. The gram-positive bacteria accounted for 292 strains (42.8%), in which the detection rate of staphylococcus aureus is highest (16.7% of total) and the detection rate of methicillin-resistant staphylococcus aureus accounted for 82.5% in staphylococcus aureus strains. Among 372 gram-negative bacteria strains (54.5%), the detection rate of bacillus aeruginosa, escherichia coli, baumannii and enterobacter cloacae were 12.5%, 11.1%, 9.1% and 8.2% respectively; extended-spectrum beta-lactamases (ESBLs) were detected in 45 (60.8%) escherichia coli and 9 (42.9%) klebsiella pneumoniae strains. Eighteen strains of fungus were found, and it decreased in last 2 years. The detection rate of opportunistic pathogenic bacteria and the antibiotic resistant strains kept increasing in the 3 years. CONCLUSIONS: Drug resistance of pathogenic bacterium is very serious in burns department. The irrational use of broad-spectrum antibiotics and the antibiotic detection of pathogenic bacterium are all contributed to the drug resistance. It is important to enhance the asepsis, prevent hospital infection, detect the pathogenic bacteria and use antibiotics rationally in burns department.

Downregulation of LSD1 suppresses the proliferation, tumorigenicity and invasion of papillary thyroid carcinoma K1 cells.

The present study aimed to evaluate the effects of lysine-specific demethylase 1 (LSD1) downregulation, induced by small interfering RNA (siRNA) transfection, on the proliferation, colony formation, migration and invasion of the papillary thyroid carcinoma K1 cell line. The siRNA targeting LSD1 and scrambled non-targeting siRNA were each transfected into papillary thyroid carcinoma K1 cells. Downregulation of LSD1 mRNA and protein level was evaluated by reverse transcription-quantitative polymerase chain reaction, and immunocytochemical (ICC) analysis and western blotting, respectively. A Cell Counting kit-8 assay was applied to estimate the effect of LSD1-siRNA on cell growth. Migration and invasion abilities were estimated by Transwell chamber assay. A soft agar colony formation assay was performed to estimate the effect of LSD1-siRNA on tumorigenicity in vitro. ICC data showed that LSD1 protein was strongly expressed in the blank and control K1 cells compared with the LSD1-siRNA cells (F=15.192, P<0.01). Compared with the control cells, cells transfected with siRNA targeting LSD1 exhibited significant downregulation of LSD1 mRNA (t=6.845, P<0.01) and protein (F=53.764, P<0.01) levels. siRNA targeting LSD1 also downregulated cell proliferation following transfection for 24, 48 and 72 h (t=4.777, P<0.001; t=3.302, P=0.003; and t=3.017, P=0.006, respectively). Compared with the control group, the amount of cell invasion was gradually reduced in the LSD1-siRNA group (t=12.301, P<0.01). The number of migrating cells was significantly higher in the negative control group compared with the LSD1-siRNA group (t=7.911, P<0.01), and the ability of colony formation in the LSD1-siRNA cells was notably reduced in the soft agar formation assay (t=3.612, P=0.005). siRNA targeting LSD1 efficiently inhibits the proliferation, colony formation, migration and invasion of papillary thyroid carcinoma K1 cells.

Mucosal fluid evaporation is not the method of heat dissipation from fourth-degree laryngopharyngeal burns.

This study was designed to explore whether mucosal fluid evaporation represents a method of heat dissipation from thermal air inhalation injury and to assess laryngopharyngeal tissue damage according to heat quantity changes of dry air and vapour. Fifteen adult male beagles were divided into five groups to inhale heated air or vapour for 10 min as follows: control group (ordinary air), group I (91-110 °C heated air), group II (148-175 °C heated air), group III (209-227 °C heated air), and group IV (96 °C saturated vapour). The heat quantity changes of the dry air and vapour were calculated via thermodynamic formulas. The macroscopic and histological features of the laryngopharynxes were examined and assessed by various tissue damage grading systems. Group IV exhibited the most serious laryngopharyngeal damage, including cilia exfoliation, submucosal thrombosis, glandular atrophy, and chondrocyte degeneration, which is indicative of fourth-degree injury. The quality, heat quantity, and proportional reduction of heat quantity of vapour in group IV were all higher than those in the other groups. Furthermore, we found that mucosal fluid evaporation is not the method of heat dissipation from thermal air inhalation injury used by the airways. Laryngopharyngeal tissue damage depends chiefly on the heat quantity of vapour in the air.

Simulation of the Velocity and Temperature Distribution of Inhalation Thermal Injury in a Human Upper Airway Model by Application of Computational Fluid Dynamics.

Inhalation injury is an important cause of death after thermal burns. This study was designed to simulate the velocity and temperature distribution of inhalation thermal injury in the upper airway in humans using computational fluid dynamics. Cervical computed tomography images of three Chinese adults were imported to Mimics software to produce three-dimensional models. After grids were established and boundary conditions were defined, the simulation time was set at 1 minute and the gas temperature was set to 80 to 320°C using ANSYS software (ANSYS, Canonsburg, PA) to simulate the velocity and temperature distribution of inhalation thermal injury. Cross-sections were cut at 2-mm intervals, and maximum airway temperature and velocity were recorded for each cross-section. The maximum velocity peaked in the lower part of the nasal cavity and then decreased with air flow. The velocities in the epiglottis and glottis were higher than those in the surrounding areas. Further, the maximum airway temperature decreased from the nasal cavity to the trachea. Computational fluid dynamics technology can be used to simulate the velocity and temperature distribution of inhaled heated air.

siRNA targeting RBP2 inhibits expression, proliferation, tumorigenicity and invasion in thyroid carcinoma cells.

In order to estimate the effects of small interfering RNA (siRNA) targeting retinoblastoma binding protein 2 (RBP2) on the proliferation, expression, invasion, migration and tumorigenicity abilities of papillary thyroid carcinoma K1 cells, siRNA targeting RBP2 (RBP2-siRNA) and negative control siRNA were transfected into K1 cells. The mRNA levels of RBP2 in the transfected cells were estimated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and the protein levels of RBP2 in these cells were evaluated by western blot analysis and immunocytochemical (ICC) analyses. The growth, tumorigenicity, migration and invasion abilities of the transfected cells were measured by Cell Counting Kit-8 (CCK-8), soft agar colony formation and transwell chamber assay, respectively. The ICC results demonstrated that the protein expression levels of RBP2 were lower in the RBP2-siRNA-transfected cells than in the blank and control cells (analysis of variance, F=26.754, P<0.01). RBP2-siRNA downregulated RBP2 at the mRNA (t=8.869) and protein level (F=60.835) (P=0.000 vs. control cells). In addition, the transfection of RBP2-siRNA into K1 cells also suppressed cell proliferation at 24, 48 and 72 h post-transfection (t=7.650, P<0.01; t=2.606, P=0.016; and t=2.377, P=0.027, respectively). Compared with the control group, the number of invasive and migrated cells were significantly reduced in the RBP2-siRNA-transfected group (t=4.774 and t=6.366, respectively; P<0.01). Furthermore, the tumorigenic potential of the cells transfected with RBP2-siRNA was markedly reduced, as indicated by the soft agar formation assay (t=2.749, P=0.014 vs. control cells). In conclusion, the transfection of RBP2-siRNA into papillary thyroid carcinoma K1 cells suppressed the expression of RBP2 in these cells, and reduced their proliferation, invasion, migration and tumorigenic potential. Therefore, targeting RBP2 may be an efficient approach to control thyroid carcinoma.

PLCE1 gene in esophageal cancer and interaction with environmental factors.

OBJECTIVE: To study the PLCE1 gene rs2274223 polymorphism with regard to esophageal cancer and its interaction with diet, lifestyle, psychological and environmental factors in Southwest Shandong province. MATERIALS AND METHODS: A case series study (case-case) was conducted. Questionnaire data were collected and 3 ml-5 ml venous blood was drawn for DNA extraction among the qualified research subjects. PLCE1 gene polymorphism was detected after PCR amplification of DNA. SPSS 13.0 software was used for statistical analysis of the data. RESULTS: The three genotypes A/A, A/G and G/G PLCE1 gene rs2274223 was 31, 16 and 4 cases, accounting for 60.8%, 31.4%, 0.08% respectively. The difference of three genotypes (AA/GA/GG) proportion between negative and positive family history of patients was statistically significant, χ2=6.213, p=0.045. There was no statistically significant relationship between PLCE1 gene rs2274223 polymorphism and smoking, drinking, χ2=0.119, p=0.998, and χ2=1.727, p=0.786. There was no linkage of the three rs2274223 PLCE1 gene genotypes (AA/GA/GG) proportion with eating fried, pickled, hot, mildew, overnight, smoked, excitant food, eat speed, salt taste or not (p>0.05). or with living environment pollution and nine risk factors of occupational exposure (p>0.05). There was no statistically significant difference in TS scores between different genotype of rs2274223 PLCE1 gene. CONCLUSIONS: The PLCE1 rs2274223 polymorphism has a relationship with family history of esophageal cancer, but does not have any significant association with age, gender, smoking, alcohol drinking, food hygiene, eating habits, living around the environment and occupation in cases.

Short low concentration cisplatin treatment leads to an epithelial mesenchymal transition-like response in DU145 prostate cancer cells.

BACKGROUND: Prostate cancer is one of the main causes of cancer death, and drug resistance is the leading reason for therapy failure. However, how this occurs is largely unknown. We therrfore aimed to study the response of DU145 cells to cisplatin. MATERIALS AND METHODS: Du145 prostate cancer cells were treated with a low dose of cisplatin for 24 h and cell viability and number were determined by MTT assay and trypan blue exclusion assay, respectively. The real time polymerase chain reaction (PCR) was used to assess responses to cisplatin treatment. RESULTS: After 24h 2 µg/ml treatment did not result in significant reduction in cell viability or number. However, it led to enhanced cancer cell invasiveness. E-cadherin mRNA was reduced, and vimentin, Snail, Slug, metalloproteinase 9 (MMP9) mRNA expression increased significantly, a feature of epithelial-mesenchymal transition (EMT). CONCLUSIONS: Short time low concentration cisplatin treatment leads to elevated invasiveness of DU145 cancer cells and this is possibly due to EMT.

"Plus-C" odorant-binding protein genes in two Drosophila species and the malaria mosquito Anopheles gambiae.

Olfaction plays a crucial role in many aspects of insect behaviour, including host selection by agricultural pests and vectors of human disease. Insect odorant-binding proteins (OBPs) are thought to function as the first step in molecular recognition and the transport of semiochemicals. The whole genome sequence of the fruit fly Drosophila melanogaster has been completed and a large number of genes have been annotated as OBPs, based on the presence of six conserved cysteine residues and a conserved spacing between the cysteines. These proteins can be divided into three distinct subgroups; those with only one six-cysteine motif, those with two such motifs and those with one motif, three extra conserved cysteines and a conserved proline immediately after the sixth cysteine. This study concentrates on the last two subgroups, referred to as 'dimer' OBPs and 'Plus-C' OBPs, respectively. We determined the tissue-specific transcript levels of all of these OBP genes of D. melanogaster using semiquantitative RT-PCR. The results showed that the expression patterns can vary within a subgroup of genes and that this technique is valuable for assessing which of the putative OBP genes are likely to be involved in Drosophila olfaction. The publicly available genomes of another fruit fly Drosophila pseudoobscura, the malaria mosquito Anopheles gambiae and the yellow fever mosquito Aedes aegypti were searched by Blast against each Plus-C OBP and dimer OBP of D. melanogaster. Related genes were found in all of the other species and the relationships of these with the D. melanogaster genes and their possible biological functions are discussed.

Revisiting the odorant-binding protein LUSH of Drosophila melanogaster: evidence for odour recognition and discrimination.

LUSH is a soluble odorant-binding protein of the fruit fly Drosophila melanogaster. Mutants not expressing this protein have been reported to lack the avoidance behaviour, exhibited by wild type flies, to high concentrations of ethanol. Very recently, the three-dimensional structure of LUSH complexed with short-chain alcohols has been resolved supporting a role for this protein in binding and detecting small alcohols. Here we report that LUSH does not bind ethanol and that wild type flies are in fact attracted by high concentrations of ethanol. We also report that LUSH binds some phthalates and that flies are repelled by such compounds. Finally, our fluorescence data, interpreted in the light of the three-dimensional structure of LUSH, indicate that the protein undergoes a major conformational change, similar to that reported for the pheromone-binding protein of Bombyx mori, but triggered, in our case, by ligand.

[Study in functional compensation of skin flap:an experimental of fast prefabricated random skin flap].

OBJECTIVE: To investigate the possibility and the limit in increasing the survival area of the random skin flap by extremely increasing the ratio of its length and width within 24 hours. METHODS: SD rats (n = 20) were chosen for this study. The rats were randomly divided into: subject group and control one. Pre-made skin flap was prepared as design. The subject group was carried out rapid pre-fabricated skin flap formation training. No training was performed in control group. The changes in perfusion value of micro-circulation inside skin flap were monitored during the whole process, and micro-circulation parameters of the skin flap were used to evaluate whether its blood circulation network was mature or not. RESULTS: Training of pre-made skin flap at 18th hour, the perfusion value of its micro-circulation was basically stable, Skin flap formation was finished at 24th hour. Survival area in control group was (68.25 +/- 0.18)% and in subject group was (97.25 +/- 0.24)% (P < 0.01). There was a significant difference between the two groups. CONCLUSIONS: Within short time, it is possible to establish micro-circulation in skin flap which exceeds the limit set by traditional theory. Digitalized judgment can be used to monitor the fast formation of super-big skin flap. This method is reliable and can increase the survival rate of random skin flap.

Firework injuries at a major trauma and burn center: A five-year prospective study.

BACKGROUND AND OBJECTIVE: In China, fireworks are an integral part of the celebration of the annual Spring Festival, but the number of injuries associated with their private use seen in emergency rooms increases dramatically. To raise awareness and help guide future prevention practices in this city, we investigated the epidemiology of firework-related injuries presented at our trauma and burn center in Beijing during the Spring Festivals of 2007-2011. METHODS: Patients were interviewed using a pre-coded questionnaire to elicit information regarding age, gender, causes, injured body part, type of injury, diagnosis, and disposition. RESULT: From 2007 to 2011, during the Spring Festivals 734 patients with fire-work related injuries were seen at our trauma and burn center in Beijing, the median patients of the five year were 140(136-150). The mean age of the patients was 26±15.3 years (range, 1-95 years). Of the 734 patients, the highest proportion of injuries were the 5-14 year-old age group The majority of the patients were male (87.9%), the overall male:female ratio was 7.41:1, and males were predominant in all age groups. For all 5 years, the incidence of firework-related injuries during the Spring Festival Holidays peaked specifically on the first, fifth, and last days, respectively. Injuries were mainly due to improper handling (415/610, 68.0%) or setting off illegal fireworks (195/610, 32.0%). The most frequently injured body parts were the hands and fingers (32.0%), head or face except eyes (28.3%), and trunk (22.4%). Burns were the most common type of injury (65.7%), most of the burned patients (437/453) were between 1% and 10%, and the most common region burned were hands and fingers (218/754). Contusions or lacerations were the second common type of injury (34.3%). Most of the patients (642, 87.5%) were treated and released, while 37 (5%) were treated and transferred, and 55 (7.5%) were admitted for advanced treatment. CONCLUSION: The private use of fireworks during the Spring Festival Holidays is associated with a considerable number of injuries to various parts of the body. We can minimize the number and severity of accidents by raising awareness of safety practices, encouraging professional displays only and motivating manufacturers to adhere to strict quality control.

Clinicopathological implications of leptin and leptin receptor expression in papillary thyroid cancer.

The role of leptin and its receptors (OBRs) in the pathogenesis of various primary human malignancies has been demonstrated. However, their expression and clinicopathological significance in papillary thyroid cancer (PTC) is not fully understood. In this study, we examined the expression of leptin and OBRs in 76 PTC samples using immunohistochemistry, and their associations with clinicopathological parameters were evaluated. The expression of OBRs was observed in the tumor cell membrane and/or cytoplasm, with a positive rate of 73.7% (56/76), while leptin was expressed in the tumor cell cytoplasm in 55 of 76 cases (72.4%). The expression of either protein was associated with greater tumor size (P=0.016 for leptin and P=0.002 for OBRs). In addition, the expression levels of leptin and OBRs were associated with each other. Neither leptin nor OBR expression levels were associated with other parameters, including age, body weight, postmenopausal state, multifocality and lymph node metastasis. These data suggest that the expression of leptin and/or OBRs in PTC is associated with tumor size and may be a potential target in PTC.

Circulational heat dissipation of upper airway: Canine model of inhalational thermal injury.

BACKGROUND: The upper airway has powerful heat-absorbing ability, in which the blood circulation may play an important role. OBJECTIVE: This study aimed to explore the circulational heat-dissipating ability, and to investigate the contribution of blood circulation to the heat-absorbing ability of upper airway. METHODS: 18 adult, male Beagle dogs were divided into three groups to inhale thermal dry air of 70-80°C, 150-160°C or 310-320°C for 20min. Blood temperatures and blood flow rates of bilateral common jugular veins (CJVs) were measured. Dogs' breathing rates and air temperatures in middle trachea were also measured. According to the formula "Q=c·m·ΔT", the heat dissipated by blood (Q-blood) and the heat release by air (Q-air) were calculated out. The contribution of circulational heat dissipation to the heat-absorbing ability of upper airway was defined as "C-blood". RESULTS: The blood temperature rise of CJV was 2.24±0.60°C. The blood flow rate of CJV was 44.5±5.9ml/min. The air temperature in middle trachea was 63.5±18.9°C. The mean breathing rate was 51.8±7.5/min. The calculated "Q-blood" and "Q-air" were 13197.3±4408.6J and 33540.2±24578.7J, and the "C-blood" was 55.2±25.0% (21.7-88.8%). CONCLUSION: Circulational heat dissipation plays an important role in the heat-absorbing process of upper airway when inhaled air is less than 160°C. However, for air higher than 160°C, some other mechanism might be dominant in the upper airway's heat-absorbing ability.

Measuring surface temperature and grading pathological changes of airway tissue in a canine model of inhalational thermal injury.

BACKGROUND: Airway tissue shows unexpected invulnerability to heated air. The mechanisms of this phenomenon are open to debate. OBJECTIVE: This study was designed to measure the surface temperatures at different locations of the airway, and to explore the relationship between the tissue's surface temperature and injury severity. METHOD: Twenty dogs were randomly divided into four groups, including three experimental groups (six dogs in each) to inhale heated air at 70-80 °C (group I), 150-160 °C (group II) and 310-320 °C (group III) and a control group (two dogs, only for histological observation). Injury time was 20 min. Mucosal surface temperatures of the epiglottis (point A), cricoid cartilage (point B) and lower trachea (point C) were measured. Dogs in group I-III were divided into three subgroups (two in each), to be assayed at 12, 24 and 36 h after injury, respectively. For each dog, four tissue parts (epiglottis, larynx, lower trachea and terminal bronchiole) were microscopically observed and graded according to an original pathological scoring system (score range: 0-27). RESULT: Surface temperatures of the airway mucosa increased slowly to 40.60±3.29 °C, and the highest peak temperature was 48.3 °C (group III, point A). The pathological score of burned tissues was 4.12±4.94 (0.0-18.0), suggesting slight to moderate injuries. Air temperature and airway location both influenced mucosal temperature and pathological scores very significantly, and there was a very significant positive correlation between tissue temperature and injury severity. CONCLUSION: Compared to the inhalational air hyperthermia, airway surface temperature was much lower, but was still positively correlated with thermal injury severity.