Changes In Physiological Indices Research Articles

Physiological Response Characteristics in Medicago sativa Under Freeze-Thaw and Deicing Salt Stress

Dongmu-1 Medicago sativa seedlings were used as the test material; the variation characteristics soluble protein, soluble sugar, malondialdehyde, proline, chlorophyll, and relative water content were studied under the artificial simulated freeze-thaw (10, 5, 0, − 3, 0, 5, and 10 °C) and combined with deicing salt stress and buffer. The results showed that freeze-thaw and high-salt stress conditions will lead to the damage in the seedling including the membrane system, lipid peroxidation, and severe dehydration. Because of the self-regulating system as well as a certain degree of resistance, the plants can accumulate plenty of substances such as soluble protein, soluble sugar, and proline so as to regulate the osmotic potential. The content of soluble protein, malondialdehyde, soluble sugar, and proline in different treatment groups rose first and then decreased within a freeze-thaw cycle, among which the content of soluble protein reached the maximum value at 0 °C (t3), 20.82, 18.96, and 17.97 mg/g, respectively. The figure for malondialdehyde and proline peaked at − 3 °C (t4) while soluble sugar content peaked at 0 °C (t5). However, during this period, there were no apparent regulations for chlorophyll content and relative water content in each treatment group. Beyond that, due to the different intensity of compound stress, the seedlings showed different adaptability, and the degree of changes in physiological indexes appeared to be combined freeze-thaw and deicing salt stress > single freeze-thaw stress > combined freeze-thaw, deicing salt stress, and buffer, illustrating that buffer can alleviate the degree of the damage from freeze-thaw and deicing salt stress on M. sativa seedlings to some extent.

Relationship Between Kinematic and Physiological Indices During Braking Events of Different Intensities.

Objective To study the relationship between physiological indices and kinematic indices during braking events of different intensities. Background Based on mental workload theory, driving and other task demands may generate changes in physiological indices, such as the driver's heart rate and skin conductance. However, no attempts were made to associate changes in physiological indices with changes in vehicle kinematics that result from the driver attempts to meet task demands. Method Twenty-five drivers participated in a field experiment. We manipulated braking demands using roadside signs to communicate the speed (km/h) before braking (50 or 60) and the target speed for braking (30 or to a complete stop). In an additional session, we asked drivers to brake as if they were responding to an impending collision. We analyzed the relationship between the intensities of braking events as measured by deceleration values (g) and changes in heart rate, heart rate variability, and skin conductance. Results All physiological indices were associated with deceleration intensity. Especially salient were the differences in physiological indices between the intensive (|g| > 0.5) and nonintensive braking events. The strongest relationship was between braking intensity and skin conductance. Conclusions Skin conductance, heart rate, and heart rate variability can mirror the mental workload elicited by varying braking intensities. Application Associating vehicle kinematics with physiological indices related to short-term driving events may help improve the performance of driver assistance systems.

Candidate SNP markers of reproductive potential are predicted by a significant change in the affinity of TATA-binding protein for human gene promoters

BackgroundThe progress of medicine, science, technology, education, and culture improves, year by year, quality of life and life expectancy of the populace. The modern human has a chance to further improve the quality and duration of his/her life and the lives of his/her loved ones by bringing their lifestyle in line with their sequenced individual genomes. With this in mind, one of genome-based developments at the junction of personalized medicine and bioinformatics will be considered in this work, where we used two Web services: (i) SNP_TATA_Comparator to search for alleles with a single nucleotide polymorphism (SNP) that alters the affinity of TATA-binding protein (TBP) for the TATA boxes of human gene promoters and (ii) PubMed to look for retrospective clinical reviews on changes in physiological indicators of reproductive potential in carriers of these alleles.ResultsA total of 126 SNP markers of female reproductive potential, capable of altering the affinity of TBP for gene promoters, were found using the two above-mentioned Web services. For example, 10 candidate SNP markers of thrombosis (e.g., rs563763767) can cause overproduction of coagulation inducers. In pregnant women, Hughes syndrome provokes thrombosis with a fatal outcome although this syndrome can be diagnosed and eliminated even at the earliest stages of its development. Thus, in women carrying any of the above SNPs, preventive treatment of this syndrome before a planned pregnancy can reduce the risk of death. Similarly, seven SNP markers predicted here (e.g., rs774688955) can elevate the risk of myocardial infarction. In line with Bowles’ lifespan theory, women carrying any of these SNPs may modify their lifestyle to improve their longevity if they can take under advisement that risks of myocardial infarction increase with age of the mother, total number of pregnancies, in multiple pregnancies, pregnancies under the age of 20, hypertension, preeclampsia, menstrual cycle irregularity, and in women smokers.ConclusionsAccording to Bowles’ lifespan theory—which links reproductive potential, quality of life, and life expectancy—the above information was compiled for those who would like to reduce risks of diseases corresponding to alleles in own sequenced genomes. Candidate SNP markers can focus the clinical analysis of unannotated SNPs, after which they may become useful for people who would like to bring their lifestyle in line with their sequenced individual genomes.

Importance of serial changes in biomarkers in idiopathic pulmonary fibrosis.

The clinical significance of serial changes in serum biomarkers in patients with idiopathic pulmonary fibrosis (IPF) remains to be established. This retrospective study was conducted to clarify the associations of serial changes in serum Krebs von den Lungen-6 (KL-6) and surfactant protein-D (SP-D) with changes in physiological indices and overall mortality in IPF.The study subjects were 75 patients with IPF. The 6 month change in serum KL-6 was significantly correlated with changes in the percentage of the predicted forced vital capacity (FVC % pred) and the percentage of the predicted diffusing capacity of the lung for carbon monoxide (% DLCO), while the 6 month change in serum SP-D was correlated only with % DLCO. During the mean follow-up period of 647 days, 22 (29.3%) patients died. An increase in serum KL-6 over a 6 month period was a significant predictor of mortality even after adjustment for %FVC, % DLCO and serum KL-6 at the baseline (hazard ratio 1.10 per 100 U·mL−1, 95% CI 1.01–1.18, p=0.03), whereas the 6 month increase in serum SP-D was not significant.Serial measurements of serum KL-6 may provide additional prognostic information compared to that provided by physiological parameters in patients with IPF.

Suppression of nuclear factor erythroid‑2‑related factor 2‑mediated antioxidative defense in the lung injury induced by chronic exposure to methamphetamine in rats.

The imbalance between oxidative stress and antioxidant defense is important in the pathogenesis of lung diseases. Nuclear factor erythroid‑2‑related factor 2 (Nrf2) is a key transcriptional factor that regulates the antioxidant response. The purpose of the present study was to investigate whether Nrf2‑mediated antioxidative defense is involved in methamphetamine (MA)‑induced lung injury in rats. Following establishment of chronic MA toxicity in rats, Doppler ultrasonic detection was used to measure the changes of physiological indexes, followed by hematoxylin and eosin staining, ELISA and western blot analysis. MA was demonstrated to increase the heart rate and peak blood flow velocity of pulmonary arterial valves and to decrease the survival rate of rats, and resulted in lung injury characterized by perivascular exudates, airspace edema, slight hemorrhage and inflammatory cell infiltration. MA significantly inhibited the expression of nuclear Nrf2 protein and its target genes (glutamate‑cysteine ligase catalytic subunit C and heme oxygenase‑1), and dose‑dependently reduced glutathione (GSH) levels and the ratio of GSH/oxidized glutathione, accompanied by increases in reactive oxygen species (ROS) levels in rat lungs. Linear regression analysis revealed that there was a positive correlation between lung ROS level and lung injury indexes. These findings suggested that chronic exposure to MA led to lung injury by suppression of Nrf2‑mediated antioxidative defense, suggesting that Nrf2 may be an important therapeutic target for MA‑induced chronic lung toxicity.

Initial validation of a virtual blood draw exposure paradigm for fear of blood and needles

Fear of blood, injections, and needles commonly prevents or delays individuals’ receipt of health care, such as vaccines or blood draws. Innovative methods are needed to overcome these fears and reduce anxiety related to activities of this nature. The present study describes initial testing of an arm illusion paradigm that may prove useful during early phases of graded exposure for people with blood and needle fear. Seventy-four undergraduate students aged 18–29 years were tested. In line with study aims, results indicated that the virtual blood draw paradigm promoted strong perceptions of arm ownership and elicited significant changes in physiological indices (blood pressure, heart rate, electrodermal activity, respiratory rate) in response to key procedure elements (e.g., needle insertion). Further, bivariate correlations indicated that individual differences in self-reported blood and needle fear collected prior to the illusion paradigm were significantly associated with presyncopal symptoms reported following the procedure. In regression analyses, self-reported measures of blood and needle fear explained unique variance in presyncopal symptoms even after controlling for general state anxiety. These findings provide initial support for the virtual blood draw paradigm as a promising tool to help provide graded exposure to medical procedures involving needles and blood draw.

Effects of 6-week Nordic walking training on body composition and antioxidant status for women > 55 years of age.

This study examined the effects of 6-week Nordic walking (NW) workout with individually customized intensity, on the body composition, and oxidative stress biomarkers for women > 55 years of age. Sixteen sedentary women (age 58.1±2.02 years old, body mass index (BMI) 26.74±2.72 kg/m2) worked out the NW 3 times/week over the 6-week period. Training intensity, which reflected the dominance of oxygen metabolism, was determined based on changes in physiological indicators during graded exercise on a treadmill (walking with poles). The body composition and oxidative stress biomarkers in blood were measured before and after the exercise routine. After the training period, body weight, body fat percentage, body mass index and uric acid levels in serum decreased significantly (p < 0.05). At the same time the plasma total antioxidant status increased considerably (p < 0.05), while the total oxidative status and the oxidized low-density lipoproteins concentration levels did not change significantly (p > 0.05). Within a relatively short time, the Nordic walking with the customized intensity level focused on the dominance of fat metabolism, decreased body fat and improved the blood antioxidant defense system for previously sedentary women. Int J Occup Med Environ Health 2017;30(3):445-454.

142: THE IMPACT OF VISITORS ON THE QUALITY OF HOSPITALIZED PATIENTS' TREATMENT

Background and aims:Visiting is one of the basic requirements of patients, but most doctors and nurses know visiting as a stressor. This study aimed to evaluate the effect of the...

STUDY ON THE BEHAVIOUR OF MINE RESCUE BRIGADESMEN EXPOSED TO HIGH TEMPERATURE AND HUMIDITY IN THE TRAINING FACILITY

Intervention and rescue activity in special conditions may be conducted only by trained and authorized personnel using individual protective breathing equipment. While working with the insulating respiratory device, there are a number of factors that make work stressful. As a rule, those working under protection of the insulating respiratory devices, besides carrying on their back a device weighing 14-18 kg, are also subject to great difficulty, in terms of securing their own safety, saving lives, quick-acting under heavy microclimate conditions (high heat and humidity). For interventions demanding predominantly physical effort, in high temperature and humidity environments, where work processes involve large muscle groups, changes in physiological indicators, during or immediately after effort, have been observed, especially in the cardiovascular system and respiratory system. In this respect, the paper presents a research on changes in physiological parameters (pulse and blood oxygen saturation) of intervention and rescue personnel in situations where they have to intervene in high temperature and humidity environments. To that effect, several teams of mine rescue brigadesmen were monitored throughout their training within the National Institute for Research and Development in Mine Safety and Protection to Explosion INSEMEX Petrosani training facility, which may generate the most unfavourable conditions that can be encountered in various emergency situations.

Breastfeeding for procedural pain in infants beyond the neonatal period.

Breastfeeding for procedural pain in infants beyond the neonatal period.

Over-expression of Gene FaASR Promotes Strawberry Fruit Coloring

Fruit development and ripening is a complicate process. Although much progress has been made on the ripenig process, the molecular mechamism of fruit development is not yet clear. In this study, we used ‘Sweet Charlie’ strawberry as test materials, based on cloning the strawberries ASR homologous gene, we carried out the bioinformatics and temporal expression analysis of FaASR, by manipulating ASR gene expression level in strawberry fruit, we tested the changes of physiological indicators, including sugar, ABA, pigments content, and fruit firmness, as well as phenotypic changes. In addition, we measured the expression changes of some anthocyanin-related gene, such as CHS and UFGT, by which we revealed the regulation mechanisms of ASR gene over strawberry fruit ripening. Strawberry ASR contained a typical domain of ABA/WDS that was related to fruit ripening and stress-resistance, and ASR gene over-expression could promote strawberry fruit coloring, endogenous ABA and sucrose accumulation, fruit softening, and induced the transcription levels of anthocyanin-related genes CHS and UFGT. The present study will further reveal the molecular mechanisms of information transmission in fruit development, and will also play an important foundation for future molecular improvement of strawberries breeding.

Native American Diabetes Prevention Intervention Programs

Background and Purpose: Diabetes is one of the biggest health problems for the American Indian and Alaska Native communities. The purpose of this study was to review lifestyle based diabetes interventions from January 1995 to January 2015. Methods: The target population within this systematic review was adult American Indians and Alaska Natives. Four databases (Medline, Google Scholar, PsychINFO, and JSTOR) were used to find articles, of which nine articles met the inclusion criteria of being either an intervention or prevention program that reported at least one physiological or biological indicator of diabetes. Results: Among the nine articles reviewed, six articles showed significant changes of physiological indicators. Three of the studies only targeted the female population. Most of the programs lasted between 6 to 12 months. A major limitation among intervention or prevention programs was an inadequate use of a theoretical behavior change model. Conclusion: Overall, it was found that physical activities and diet -based methods have the potential for diabetes prevention and intervention programs among American Indian and Alaska Native populations. Recommendations for future research include using randomized controlled trial research design, and using theory to guide program development.

Behavioral and Neural Enhancing Effects of a Summer Treatment Program in Children with Attention Deficit Hyperactivity Disorder

Deficiency in executive functioning is a core symptom of attention deficit hyperactivity disorder (ADHD). The brain part responsible for executive functions is the prefrontal cortex (PFC). Although drug-based interventions can improve PFC activity, reports on PFC activity being improved by behavioral treatment are lacking. We evaluated whether a summer treatment program (STP) administering comprehensive behavioral treatment would increase PFC activity in children with ADHD. We examined behavioral and neural changes in 20 children before and after the STP, conducted over a 2-week period. We asked the parents/guardians to complete the Swanson, Nolan, and Pelham IV scale to assess severity of ADHD. The main task evaluating executive control was the reverse Stroop task. To examine changes in physiological indices, we used near-infrared spectroscopy to measure changes in PFC activity. Subjective assessments by parents/guardians indicated that ADHD symptoms improved significantly. There was also significant improvement in the number of correct responses and interference rates in the reverse Stroop task. Furthermore, post-intervention PFC activity was significantly higher. These results suggest that the STP improved inhibitory control in executive function, which is considered as a key symptom of ADHD. The increase in PFC activity further suggests that the STP improves cognition through neural function.

Seasonal Variations in V[Combining Dot Above]O2max, O2-Cost, O2-Deficit, and Performance in Elite Cross-Country Skiers

Long-term effects of training are important information for athletes, coaches, and scientists when associating changes in physiological indices with changes in performance. Therefore, this study monitored changes in aerobic and anaerobic capacities and performance in a group of elite cross-country skiers during a full sport season. Thirteen men (age, 23 ± 2 years; height, 182 ± 6 cm; body mass, 76 ± 8 kg; V2 roller ski skating VO2max, 79.3 ± 4.4 ml·kg·min or 6.0 ± 0.5 L·min) were tested during the early, middle, and late preparation phase: June (T1), August (T2), and October (T3); during the competition phase: January/February (T4); and after early precompetition phase: June (T5). O2-cost during submaximal efforts, V[Combining Dot Above]O2peak, accumulated oxygen deficit (ΣO2-deficit), and performance during a 1,000-m test were determined in the V2 ski skating technique on a roller ski treadmill. Subjects performed their training on an individual basis, and detailed training logs were categorized into different intensity zones and exercise modes. Total training volume was highest during the summer months (early preseason) and decreased toward and through the winter season, whereas the volume of high-intensity training increased (all p < 0.05). There was a significant main effect among testing sessions for 1,000 m time, O2-cost, and ΣO2-deficit (Cohen's d effect size; ES = 0.63-1.37, moderate to large, all p < 0.05). In general, the changes occurred between T1 and T3 with minor changes in the competitive season (T3 to T4). No significant changes were found in V[Combining Dot Above]O2peak across the year (ES = 0.17, trivial). In conclusion, the training performed by elite cross-country skiers induced no significant changes in V[Combining Dot Above]O2peak but improved performance, O2-cost, and ΣO2-deficit.

The low temperature induced physiological responses of Avena nuda L., a cold-tolerant plant species.

The paperaim of the was to study the effect of low temperature stress on Avena nuda L. seedlings. Cold stress leads to many changes of physiological indices, such as membrane permeability, free proline content, malondialdehyde (MDA) content, and chlorophyll content. Cold stress also leads to changes of some protected enzymes such as peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT). We have measured and compared these indices of seedling leaves under low temperature and normal temperature. The proline and MDA contents were increased compared with control; the chlorophyll content gradually decreased with the prolongation of low temperature stress. The activities of SOD, POD, and CAT were increased under low temperature. The study was designated to explore the physiological mechanism of cold tolerance in naked oats for the first time and also provided theoretical basis for cultivation and antibiotic breeding in Avena nuda L.

How lifespan associated genes modulate aging changes: lessons from analysis of longitudinal data.

Background and Objective: The influence of genes on human lifespan is mediated by biological processes that characterize body's functioning. The age trajectories of these processes contain important information about mechanisms linking aging, health, and lifespan. The objective of this paper is to investigate regularities of aging changes in different groups of individuals, including individuals with different genetic background, as well as their connections with health and lifespan. Data and Method: To reach this objective we used longitudinal data on four physiological variables, information about health and lifespan collected in the Framingham Heart Study (FHS), data on longevity alleles detected in earlier study, as well as methods of statistical modeling. Results: We found that phenotypes of exceptional longevity and health are linked to distinct types of changes in physiological indices during aging. We also found that components of aging changes differ in groups of individuals with different genetic background. Conclusions: These results suggest that factors responsible for exceptional longevity and health are not necessary the same, and that postponing aging changes is associated with extreme longevity. The genetic factors which increase lifespan are associated with physiological changes typical of healthy and long-living individuals, smaller mortality risks from cancer and CVD and better estimates of adaptive capacity in statistical modeling. This indicates that extreme longevity and health related traits are likely to be less heterogeneous phenotypes than lifespan, and studying these phenotypes separately from lifespan may provide additional information about mechanisms of human aging and its relation to chronic diseases and lifespan.

Effect of acupoint massage therapy on the insomnia of patients with therapeutic ERCP

Objective To explore the effect of acupoint massage therapy on the insomnia of patients with therapeutic ERCP(Endoscopic Retrograde Cholangiopancreatography).Methods Totals of 124 cases were randomly divided into control group and experimental group,with 62 cases in each groups.Control group received routine nursing care,while experimental group received acupoint massage therapy and routine care.Observed changes of physiological indexes in each group patients,and assessed therapeutic effect using Pittsburgh Sleep Quality Index(PSQI),Self-rating Anxiety Scale(SAS) and Seff-Rating Scale of Sleep(SRSS).Results After intervention,the heart rate (HR),nausea in experimental group were significantly improved than that of before intervention (P ＜ 0.01),and the score of PSQI (30.10 ± 5.82),SAS (5.02 ± 3.41),SRSS (21.99 ± 3.05)were significantly lower than that of before intervention and control group (P ＜ 0.01).The therapy effect in experimental group was significantly higher than that in control group (effective rate 83.9％ vs 58.1％ ;Z =-2.023,P ＜ 0.05).Conclusions Acupoint massage therapy can improve patients ' anxiety,and improve sleeping process and quality. Key words: Acupoint massage; Insomnia; ERCP; Sleeping quality; Anxiety

English

The effects of an endophytic fungal elicitor from&nbsp;Cunninghamella&nbsp;sp. (AL4) on the volatile oil production and defence responses of host plant&nbsp;Atractylodes lancea&nbsp;were investigated. The aim was to improve the capability of endophytic fungi resources in promoting medicinal plant secondary metabolites. The results showed that the endophytic fungal elicitor significantly stimulated volatile oil accumulation. The best inducing concentration of the elicitor for volatile oil production was 30 mgL-1. The highest amount of volatile oil was harvested&nbsp;9&nbsp;days (d) after elicitor treatment. The activity of 3-hydroxy-3-methylglutaryl CoA reductase increased by 2.79-folds compared with the control of&nbsp;7&nbsp;d after treatment. The elicitor also enhanced the activities of phenylalanine ammonia-lyase, peroxidase superoxide dismutase, polyphenol oxidase, and catalase. These enhanced activities led to improvedplant defence-related secondary metabolite synthesis ability. In addition, the elicitor-treated cells were consistently healthy, and had slightly increased biomass. The results demonstrated for the first time the optimal induction time and concentration of the endophytic fungal elicitor, as well as the changes in physiological indices after endophyte-host interaction. The information provided in the present study may be applied in large-scale medicinal plant suspension cultures. &nbsp; Key words:&nbsp;Endophytic fungus, fungal elicitor,&nbsp;Atractylodes lancea,&nbsp;volatile oil,Cunninghamella&nbsp;sp.

SHORT COMMUNICATION: Organogenesis and somatic embryogenesis in callus derived from HBsAg-transgenic tomato mutant

Guan, Z.-j., Guo, B., Huo, Y.-l., Guan, Z.-p., Dai, J.-k. and Wei, Y.-h. 2012. Short Communication: Organogenesis and somatic embryogenesis in callus derived from HBsAg-transgenic tomato mutant. Can. J. Plant Sci. 92: 747-756. In the process of hepatitis B surface antigen (HBsAg) gene transformation, a transgenic cherry tomato (Lycopersivon esculentum Mill.) mutant N244 was occasionally obtained. Based on its obvious variation in ploidy and phenotypic characteristics, morphogenesis and development in the mutant in vitro were studied by cytological analysis and ultrastructural examination. The adventitious shoot primordia first emerged in the mutant N244 leaf explants after 14 d of culture, and the somatic embryo pathway developed after 35 d. Transmission electron microscopy and scanning electron microscopy further indicated that during the explant's development, there were significant changes in morphology and quantity of some organelles in N244 callus cells. On the 7th day of culture, there was little cytoplasm and few organelles, except for a large number of dense lipid bodies in the mutant callus cells. In the later stage, the changes in chloroplasts, Golgi bodies and mitochondria showed obvious difference between N244 callus cells and the control. In addition, changes in physiological indexes (growth rate, soluble protein content, and antioxidant enzyme activities) at different development stages further revealed morphogenic variation of organogenesis and somatic embryogenesis in N244 callus. The growth rate of the mutant N244 was less rapid than that of the control during its callus differentiation, and the soluble protein content of N244 callus decreased from the explant's cultivation stage until the 28th day of culture. The mutant N244 had distinct differences in variation tendency of superoxide dismutase, catalase and peroxidase activities compared with the control at every stage of callus development. These findings provide the first report of simultaneous shoot organogenesis and somatic embryogenesis of transgenic mutant and help us to understand the development mechanism of transgenic plant mutant in vitro.

Retrospective analysis of related factors for patients with weaning difficulties in medical intensive care unit

To explore the related factors of difficult-to-wean patients in medical intensive care unit (MICU). A retrospective analysis was performed for 112 patients placed on mechanical ventilation. There were 63 males and 49 females with a mean age of (58 ± 26) years. Their primary diseases included acute exacerbation of chronic obstructive pulmonary disease (AECOPD) (n = 27), pneumonia (n = 20), asthma (n = 12) and neuromuscular diseases (n = 8). Basic admission profiles, underlying diseases, accompanying diseases and pre-weaning changes in physiological indicators were recorded. They were divided into 2 groups: successfully-weaned group and different-to-wean group. Logistic regression analysis was used to analyze the risk factors correlated with the difficult withdrawal of mechanical ventilation. There were 27 (24.1%) difficult-to-wean patients on mechanical ventilation in MICU. Some underlying diseases had statistical significance in both groups, including AECOPD (χ(2) = 6.238, P = 0.028), idiopathic pulmonary fibrosis (χ(2) = 5.232, P = 0.025) and neuromuscular disease (χ(2) = 14.635, P = 0.007). The ratios of difficult-to-wean patients were 9/27, 2/6 and 6/8 respectively. There was statistical significance of pre-admission and pre-weaning oxygenation index between two groups (t = 2.183, 2.162, P < 0.05). Zubrod score at pre-weaning was also significantly different between two groups (t = 9.037, P < 0.05). Logistic regression indicated that the patients with severe heart failure (OR = 5.781), psychological disorders (OR = 4.654), obstructive sleep apnea (OR = 4.012), AECOPD (OR = 3.617) and neuromuscular diseases (OR = 2.885) were more vulnerable to weaning difficulties. The major risk factors of difficult-to-wean patients in MICU include severe heart failure, psychological diseases, obstructive sleep apnea, neuromuscular disease and AECOPD. And oxygenation and self-care capability may also affect weaning significantly.