Oxygen therapy for exercise capacity in fibrotic interstitial lung disease: A systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Fibrotic interstitial lung disease (fILD) is characterised primarily by impaired lung function and quality of life. The present study investigated whether oxygen therapy could improve exercise capacity among patients with fILD.

METHODS

Previously published randomised controlled trials (RCTs) were surveyed. A systematic review and meta-analysis was conducted to evaluate the effectiveness of oxygen therapy in improving the exertional capacity of patients with fILD. The primary outcome was peripheral oxygen saturation (SpO2) during exercise. The effects of oxygen therapy on fatigue, dyspnoea, heart rate, and exercise duration or distance were also analysed.

RESULTS

Fourteen RCTs involving 370 patients were included. Oxygen therapy improved SpO2 during exercise (mean difference, MD = 6.26 %), exercise duration (MD = 122.15 s), fatigue (standard mean difference, SMD = -0.30), and dyspnoea (MD = -0.75 Borg score units). High-flow oxygen systems tended to be more effective than low-flow systems in improving exercising SpO2, duration, fatigue, dyspnoea, and heart rate. High-flow nasal cannulas (HFNCs) yielded better outcomes regarding SpO2 and fatigue than did high-flow Venturi masks (MD = 1.60 % and MD = -1.19 Borg score units, respectively). No major adverse events were reported.

CONCLUSION

The evidence from RCTs supports the short-term use of oxygen supplementation to improve SpO2, exercise capacity, fatigue, and dyspnoea among patients with fILD. Further analyses demonstrates that HFNCs yield more favourable outcomes, yet not reaching statistical significance except for improving SpO2 and fatigue. However, the long-term effects of oxygen therapy on quality of life and mortality remain unclear.

Neutralization of CX3CL1 Attenuates TGF-β-Induced Fibroblast Differentiation Through NF-κB Activation and Mitochondrial Dysfunction in Airway Fibrosis

BACKGROUND

Severe asthma, characterized by inflammation and airway remodeling, involves fibroblast differentiation into myofibroblasts expressing α-SMA. This process leads to the production of fibronectin and connective tissue growth factor (CTGF), driven by factors such as transforming growth factor (TGF)-β. Furthermore, the persistent presence of myofibroblasts is associated with resistance to apoptosis and mitochondrial dysfunction. The chemokine (C-X3-C motif) ligand 1 (CX3CL1) plays a role in tissue fibrosis. However, it is currently unknown whether neutralization of CX3CL1 decreases TGF-β-induced fibroblast differentiation and mitochondrial dysfunction in normal human lung fibroblasts (NHLFs).

METHODS

CX3CL1/C-X3-C motif chemokine receptor 1 (CX3CR1), CX3CL1 was analyzed by immunofluorescence (IF) or immunohistochemical (IHC) staining of ovalbumin-challenged mice. CX3CL1 release was detected by ELISA. TGF-β-induced CTGF, fibronectin, and α-SMA expression were evaluated in NHLFs following neutralization of CX3CL1 (TP213) treatment for the indicated times by Western blotting or IF staining. Mitochondrion function was detected by a JC-1 assay and seahorse assay. Cell apoptosis was observed by a terminal uridine nick-end labeling (TUNEL) assay.

RESULTS

An increase in CX3CL1 expression was observed in lung tissues from mice with ovalbumin-induced asthma by IF staining. CX3CR1 was increased in the subepithelial layer of the airway by IHC staining. Moreover, CX3CR1 small interfering (si)RNA downregulated TGF-β-induced CTGF and fibronectin expression in NHLFs. CX3CL1 induced CTGF and fibronectin expression in NHLFs. TGF-β-induced CX3CL1 secretion from NHLFs. Furthermore, TP213 decreased TGF-β-induced CTGF, fibronectin, and α-SMA expression in NHLFs. Mitochondrion-related differentially expressed genes (DEGs) were examined after CX3CL1 neutralization in TGF-β-treated NHLFs. TP213 alleviated TGF-β-induced mitochondrial dysfunction and apoptosis resistance in NHLFs. CX3CL1 induced p65, IκBα, and IKKα phosphorylation in a time-dependent manner. Furthermore, CX3CL1-induced fibronectin expression and JC-1 monomer were decreased by p65 siRNA. TP213 reduced TGF-β-induced p65 and α-SMA expression in NHLFs.

CONCLUSIONS

These findings suggest that neutralizing CX3CL1 attenuates lung fibroblast activation and mitochondrial dysfunction. Understanding the impacts of CX3CL1 neutralization on fibroblast mitochondrial function could contribute to the development of therapeutic strategies for managing airway remodeling in severe asthma.

Associations between air pollution, intracellular-to-extracellular water distribution, and obstructive sleep apnea manifestations

Background

Exposure to air pollution may be a risk factor for obstructive sleep apnea (OSA) because air pollution may alter body water distribution and aggravate OSA manifestations.

Objectives

This study aimed to investigate the mediating effects of air pollution on the exacerbation of OSA severity through body water distribution.

Methods

This retrospective study analyzed body composition and polysomnographic data collected from a sleep center in Northern Taiwan. Air pollution exposure was estimated using an adjusted nearest method, registered residential addresses, and data from the databases of government air quality motioning stations. Next, regression models were employed to determine the associations between estimated air pollution exposure levels (exposure for 1, 3, 6, and 12 months), OSA manifestations (sleep-disordered breathing indices and respiratory event duration), and body fluid parameters (total body water and body water distribution). The association between air pollution and OSA risk was determined.

Results

Significant associations between OSA manifestations and short-term (1 month) exposure to PM_2.5 and PM₁₀ were identified. Similarly, significant associations were identified among total body water and body water distribution (intracellular-to-extracellular body water distribution), short-term (1 month) exposure to PM_2.5 and PM₁₀, and medium-term (3 months) exposure to PM₁₀. Body water distribution might be a mediator that aggravates OSA manifestations, and short-term exposure to PM_2.5 and PM₁₀ may be a risk factor for OSA.

Conclusion

Because exposure to PM_2.5 and PM₁₀ may be a risk factor for OSA that exacerbates OSA manifestations and exposure to particulate pollutants may affect OSA manifestations or alter body water distribution to affect OSA manifestations, mitigating exposure to particulate pollutants may improve OSA manifestations and reduce the risk of OSA. Furthermore, this study elucidated the potential mechanisms underlying the relationship between air pollution, body fluid parameters, and OSA severity.

Associations of the distance-saturation product and low-attenuation area percentage in pulmonary computed tomography with acute exacerbation in patients with chronic obstructive pulmonary disease

Background

Chronic obstructive pulmonary disease (COPD) has high global health concerns, and previous research proposed various indicators to predict mortality, such as the distance-saturation product (DSP), derived from the 6-min walk test (6MWT), and the low-attenuation area percentage (LAA%) in pulmonary computed tomographic images. However, the feasibility of using these indicators to evaluate the stability of COPD still remains to be investigated. Associations of the DSP and LAA% with other COPD-related clinical parameters are also unknown. This study, thus, aimed to explore these associations.

Methods

This retrospective study enrolled 111 patients with COPD from northern Taiwan. Individuals' data we collected included results of a pulmonary function test (PFT), 6MWT, life quality survey [i.e., the modified Medical Research Council (mMRC) scale and COPD assessment test (CAT)], history of acute exacerbation of COPD (AECOPD), and LAA%. Next, the DSP was derived by the distance walked and the lowest oxygen saturation recorded during the 6MWT. In addition, the DSP and clinical phenotype grouping based on clinically significant outcomes by previous study approaches were employed for further investigation (i.e., DSP of 290 m%, LAA% of 20%, and AECOPD frequency of ≥1). Mean comparisons and linear and logistic regression models were utilized to explore associations among the assessed variables.

Results

The low-DSP group (<290 m%) had significantly higher values for the mMRC, CAT, AECOPD frequency, and LAA% at different lung volume scales (total, right, and left), whereas it had lower values of the PFT and 6MWT parameters compared to the high-DSP group. Significant associations (with high odds ratios) were observed of the mMRC, CAT, AECOPD frequency, and PFT with low- and high-DSP groupings. Next, the risk of having AECOPD was associated with the mMRC, CAT, DSP, and LAA% (for the total, right, and left lungs).

Conclusion

A lower value of the DSP was related to a greater worsening of symptoms, more-frequent exacerbations, poorer pulmonary function, and more-severe emphysema (higher LAA%). These readily determined parameters, including the DSP and LAA%, can serve as indicators for assessing the COPD clinical course and may can serve as a guide to corresponding treatments.

Screening the risk of obstructive sleep apnea by utilizing supervised learning techniques based on anthropometric features and snoring events

Objectives

Obstructive sleep apnea (OSA) is typically diagnosed by polysomnography (PSG). However, PSG is time-consuming and has some clinical limitations. This study thus aimed to establish machine learning models to screen for the risk of having moderate-to-severe and severe OSA based on easily acquired features.

Methods

We collected PSG data on 3529 patients from Taiwan and further derived the number of snoring events. Their baseline characteristics and anthropometric measures were obtained, and correlations among the collected variables were investigated. Next, six common supervised machine learning techniques were utilized, including random forest (RF), extreme gradient boosting (XGBoost), k-nearest neighbor (kNN), support vector machine (SVM), logistic regression (LR), and naïve Bayes (NB). First, data were independently separated into a training and validation dataset (80%) and a test dataset (20%). The approach with the highest accuracy in the training and validation phase was employed to classify the test dataset. Next, feature importance was investigated by calculating the Shapley value of every factor, which represented the impact on OSA risk screening.

Results

The RF produced the highest accuracy (of >70%) in the training and validation phase in screening for both OSA severities. Hence, we employed the RF to classify the test dataset, and results showed a 79.32% accuracy for moderate-to-severe OSA and 74.37% accuracy for severe OSA. Snoring events and the visceral fat level were the most and second most essential features of screening for OSA risk.

Conclusions

The established model can be considered for screening for the risk of having moderate-to-severe or severe OSA.

Machine learning approaches for predicting sleep arousal response based on heart rate variability, oxygen saturation, and body profiles

Objective

Obstructive sleep apnea is a global health concern, and several tools have been developed to screen its severity. However, most tools focus on respiratory events instead of sleep arousal, which can also affect sleep efficiency. This study employed easy-to-measure parameters-namely heart rate variability, oxygen saturation, and body profiles-to predict arousal occurrence.

Methods

Body profiles and polysomnography recordings were collected from 659 patients. Continuous heart rate variability and oximetry measurements were performed and then labeled based on the presence of sleep arousal. The dataset, comprising five body profiles, mean heart rate, six heart rate variability, and five oximetry variables, was then split into 80% training/validation and 20% testing datasets. Eight machine learning approaches were employed. The model with the highest accuracy, area under the receiver operating characteristic curve, and area under the precision recall curve values in the training/validation dataset was applied to the testing dataset and to determine feature importance.

Results

InceptionTime, which exhibited superior performance in predicting sleep arousal in the training dataset, was used to classify the testing dataset and explore feature importance. In the testing dataset, InceptionTime achieved an accuracy of 76.21%, an area under the receiver operating characteristic curve of 84.33%, and an area under the precision recall curve of 86.28%. The standard deviations of time intervals between successive normal heartbeats and the square roots of the means of the squares of successive differences between normal heartbeats were predominant predictors of arousal occurrence.

Conclusions

The established models can be considered for screening sleep arousal occurrence or integrated in wearable devices for home-based sleep examination.

Amphiregulin induces CCN2 and fibronectin expression by TGF-β through EGFR-dependent pathway in lung epithelial cells

BACKGROUND

Airway fibrosis is one of the pathological characteristics of severe asthma. Transforming growth factor (TGF)-β has been known to promote epithelial-mesenchymal transition formation and to play a role in the progression of tissue fibrosis. Cellular communication network factor 2 (CCN2) and fibronectin (FN) are well-known markers of EMT and fibrosis. However, whether AREG is involved in TGF-β-induced CCN2 and FN expression in human lung epithelial cells is unknown.

METHODS

AREG and FN were analyzed by immunofluorescence staining on ovalbumin-challenged mice. CCN2 and FN expression were evaluated in human lung epithelial (A459) cells following TGF or AREG treatment for the indicated times. Secreted AREG from A549 cells was detected by ELISA. Cell migration was observed by a wound healing assay. Chromatin immunoprecipitation was used to detect the c-Jun binding to the CCN2 promoter.

RESULTS

AREG and FN expression colocalized in lung tissues from mice with ovalbumin-induced asthma by immunofluorescence staining. Moreover, TGF-β caused the release of AREG from A549 cells into the medium. Smad3 siRNA down-regulated AREG expression. AREG also stimulated CCN2 and FN expression, JNK and c-Jun phosphorylation, and cell migration in A549 cells. AREG small interfering (si) RNA inhibited TGF-β-induced expression of CCN2, FN, and cell migration. Furthermore, AREG-induced CCN2 and FN expression were inhibited by EGFR siRNA, a JNK inhibitor (SP600125), and an activator protein-1 (AP-1) inhibitor (curcumin). EGFR siRNA attenuated AREG-induced JNK and c-Jun phosphorylation. Moreover, SP600125 downregulated AREG-induced c-Jun phosphorylation.

CONCLUSION

These results suggested that AREG mediates the TGF-β-induced EMT in human lung epithelial cells through EGFR/JNK/AP-1 activation. Understanding the role of AREG in the EMT could foster the development of therapeutic strategies for airway remodeling in severe asthma.

Associations among sleep-disordered breathing, arousal response, and risk of mild cognitive impairment in a northern Taiwan population

STUDY OBJECTIVES

Dementia is associated with sleep disorders. However, the relationship between dementia and sleep arousal remains unclear. This study explored the associations among sleep parameters, arousal responses, and risk of mild cognitive impairment (MCI).

METHODS

Participants with the chief complaints of memory problems and sleep disorders were screened from the sleep center database of Taipei Medical University Shuang-Ho Hospital, and the parameters related to the Cognitive Abilities Screening Instrument (CASI), Clinical Dementia Rating (CDR), and polysomnography (PSG) were determined. All the examinations were conducted within 6 months and without a particular order. The participants were divided into those without cognitive impairment (CDR = 0) and those with MCI (CDR = 0.5). Mean comparison, linear regression models, and logistic regression models were employed to investigate the associations among obtained variables.

RESULTS

This study included 31 participants without MCI and 37 with MCI (17 with amnestic MCI; 20 with multidomain MCI). Patients with MCI had significantly higher mean values of the spontaneous arousal index (SpArI) and SpArI in the nonrapid eye movement (NREM) stage (SpArI_NREM) than those without MCI. An increased risk of MCI was significantly associated with an increase SpArI and SpArI_NREM with various adjustments. Significant associations between the CASI scores and the oximetry parameters and sleep disorder indexes were observed.

CONCLUSIONS

Repetitive respiratory events with hypoxia were associated with cognitive dysfunction. Spontaneous arousal, especially in NREM sleep, was related to the risk of MCI. However, additional longitudinal studies are required to confirm their causality.

Hypoxia-induced preadipocyte factor 1 expression in human lung fibroblasts through ERK/PEA3/c-Jun pathway

Background

Several studies have reported that hypoxia plays a pathological role in severe asthma and tissue fibrosis. Our previous study showed that hypoxia induces A disintegrin and metalloproteinase 17 (ADAM17) expression in human lung fibroblasts. Moreover, preadipocyte factor 1 (Pref-1) is cleaved by ADAM17, which participates in adipocyte differentiation. Furthermore, Pref­1 overexpression is involved in tissue fibrosis including liver and heart. Extracellular signal-regulated kinase (ERK) could active downstram gene expression through polyoma enhancer activator 3 (PEA3) phosphorylation. Studies have demonstrated that PEA3 and activator protein 1 (AP-1) play crucial roles in lung fibrosis, and the Pref-1 promoter region contains PEA3 and AP-1 binding sites as predicted. However, the roles of ERK, PEA3, and AP-1 in hypoxia-stimulated Pref-1 expression in human lung fibroblasts remain unknown.

Methods

The protein expression in ovalbumin (OVA)-induced asthmatic mice was performed by immunohistochemistry and immunofluorescence. The protein expression or the mRNA level in human lung fibroblasts (WI-38) was detected by western blot or quantitative PCR. Small interfering (si) RNA was used to knockdown gene expression. The collaboration with PEA3 and c-Jun were determined by coimmunoprecipitation. Translocation of PEA3 from the cytosol to the nucleus was observed by immunocytochemistry. The binding ability of PEA3 and AP-1 to Pref-1 promoter was assessed by chromatin immunoprecipitation.

Results

Pref-1 and hypoxia-inducible factor 1α (HIF-1α) were expressed in the lung sections of OVA-treated mice. Colocalization of PEA3 and Fibronectin was detected in lung sections from OVA-treated mice. Futhermore, Hypoxia induced Pref­1 protein upregulation and mRNA expression in human lung fibroblasts (WI­38 cells). In 60 confluent WI-38 cells, hypoxia up-regulated HIF-1α and Pref-1 protein expression. Moreover, PEA3 small interfering (si) RNA decreased the expression of hypoxia-induced Pref­1 in WI­38 cells. Hypoxia induced PEA3 phosphorylation, translocation of PEA3 from the cytosol to the nucleus, PEA3 recruitment and AP-1 binding to the Pref­1 promoter region, and PEA3-luciferase activity. Additionally, hypoxia induced c-Jun-PEA3 complex formation. U0126 (an ERK inhibitor), curcumin (an AP­1 inhibitor) or c-Jun siRNA downregulated hypoxia-induced Pref-1 expression.

Conclusions

These results implied that ERK, PEA3, and AP­1 participate in hypoxia­induced Pref­1 expression in human lung fibroblasts.

Abnormal ADAM17 expression causes airway fibrosis in chronic obstructive asthma

Patients with chronic obstructive asthma (COA) develop airflow obstruction caused by subepithelial fibrosis. Although a disintegrin and metalloproteinase 17 (ADAM17) has been implicated in lung inflammation and tissue fibrosis, its role in airway fibrosis in COA has not been explored. Here, we found marked overexpression of ADAM17, phosphorylated ADAM17, and connective tissue growth factor (CTGF) in human airway fibroblasts from COA patients, compared with those of normal subjects. Similarly, levels of ADAM17, CTGF, α-smooth muscle actin (α-SMA), and collagen were increased in endobronchial biopsies from COA patients, but not in controls. In an ovalbumin-challenge asthma model, airway fibrosis was inhibited in ADAM17^f/f/Cre⁺ mice compared to control mice. TGF-β- and thrombin-induced fibrotic protein expression was reduced by ADAM17 small interfering (si)RNA, TAPI-0 (an ADAM17 inhibitor), and EGFR siRNA. In addition, exogenous HB-EGF reversed fibrotic response in ADAM17 knockdown human lung fibroblasts. ADAM17 causes subepithelial fibrosis through regulation of enhanced extracellular matrix production and fibroblast differentiation and is the common pathway for airway fibrosis mediated by TGF-β and thrombin through an aberrant ADAM17/EGFR signalling pathway.

389 The Association between Arousals and Neurochemical Biomarkers Accumulation in Obstructive Sleep Apnea with Low Arousal Threshold

Introduction

Previous studies indicated the accumulation of neurodegenerative protein may be caused by higher Obstructive sleep apnea syndrome (OSAS) severity. However, the association between arousal-related parameters induced by OSAS and the amyloid burden remains unclear. The aim of this study is to investigate the association between arousal threshold (ArTH) and neurochemical protein accumulation in OSAS patients.

Methods

Suspected OSAS participants were performed Mini-mental status examination (MMSE) and full-night polysomnography (PSG) in the sleep center of Taipei Medical University Shuang Ho Hospital, Taiwan. On the same morning, the blood samples were obtained from the participants. The concentrations of total Tau (T-Tau) and amyloid beta peptide 42 (Aβ42) were quantified by ultra-sensitive immunomagnetic reduction assays. An overall of 23 participants were enrolled and classified into Low ArTH group (n=12) and High ArTH group (n=11) based on low ArTH criteria. Regarding the statistical methods, for categorical variables and continuous variables, Fisher’s exact test and Mann-Whitney U test were performed to investigate the differences between groups, respectively. The associations between biomarkers concentrations and PSG parameters were assessed by Spearman’s correlation.

Results

Regarding the demographic characteristics in two subgroups, significantly lower body-mass index and OSAS severity were noted in Low ArTH group (p&lt;0.05). The MMSE was in normal range in both groups and had no significant differences in subgroups. For PSG parameters, there were significantly lower desaturation index, AHI and higher spontaneous arousals index in each sleep stage in Low ArTH group (p&lt;0.01). Nevertheless, in the plasma neurochemical biomarkers, Aβ42 and Aβ42 X T-Tau were significantly higher in Low ArTH group (p&lt;0.05). Moreover, in Low ArTH group, T-Tau was positively correlated with respiratory arousals index (r=0.61, p&lt;0.05) and all arousals index (r=0.76, p&lt;0.01), respectively. The positive correlations between Aβ42 X T-Tau and respiratory arousals index (r=0.62, p&lt;0.05), all arousals index (r=0.75, p&lt;0.01) could also be observed. There were no significant correlations noted in High ArTH group.

Conclusion

OSAS patients with low ArTH have higher neurochemical biomarker levels. Also, the significantly positive correlations between arousals and biomarkers were observed in that group.

Support (if any):

TGF-β Induced CTGF Expression in Human Lung Epithelial Cells through ERK, ADAM17, RSK1, and C/EBPβ Pathways

Background: Lung epithelial cells play critical roles in idiopathic pulmonary fibrosis. Methods: In the present study, we investigated whether transforming growth factor-β (TGF-β)-induced expression of connective tissue growth factor (CTGF) was regulated by the extracellular signal-regulated kinase (ERK)/a disintegrin and metalloproteinase 17 (ADAM17)/ribosomal S6 kinases 1 (RSK1)/CCAAT/enhancer-binding protein β (C/EBPβ) signaling pathway in human lung epithelial cells (A549). Results: Our results revealed that TGF-β-induced CTGF expression was weakened by ADAM17 small interfering RNA (ADAM17 siRNA), TNF-α processing inhibitor-0 (TAPI-0, an ADAM17 inhibitor), U0126 (an ERK inhibitor), RSK1 siRNA, and C/EBPβ siRNA. TGF-β-induced ERK phosphorylation as well as ADAM17 phosphorylation was attenuated by U0126. The TGF-β-induced increase in RSK1 phosphorylation was inhibited by TAPI-0 and U0126. TGF-β-induced C/EBPβ phosphorylation was weakened by U0126, ADAM17 siRNA, and RSK1 siRNA. In addition, TGF-β increased the recruitment of C/EBPβ to the CTGF promoter. Furthermore, TGF-β enhanced fibronectin (FN), an epithelial–mesenchymal transition (EMT) marker, and CTGF mRNA levels and reduced E-cadherin mRNA levels. Moreover, TGF-β-stimulated FN protein expression was reduced by ADAM17 siRNA and CTGF siRNA. Conclusion: The results suggested that TGF-β induces CTGF expression through the ERK/ADAM17/RSK1/C/EBPβ signaling pathway. Moreover, ADAM17 and CTGF participate in TGF-β-induced FN expression in human lung epithelial cells.

Mammalian target of rapamycin and p70S6K mediate thrombin-induced nuclear factor-κB activation and IL-8/CXCL8 release in human lung epithelial cells

Thrombin plays a crucial role in lung inflammatory diseases such as asthma and chronic obstructive pulmonary disease (COPD). Thrombin induces the release of interleukin-8 (IL-8)/CXCL8 by lung epithelial cells, and this phenomenon plays a vital role in lung inflammation. Our previous studies have indicated that thrombin stimulates IL-8/CXCL8 expression through PI3K/Akt/IκB kinase (IKK)α/β/nuclear factor-κB (NF-κB) and p300 pathways in human lung epithelial cells. In the present study, we explored the roles of mammalian target of rapamycin (mTOR) and p70S6 kinase (p70S6K) in thrombin-induced NF-κB activation and IL-8/CXCL8 release in human lung epithelial cells. In this study, we found that rapamycin (an mTOR inhibitor) and p70S6K siRNA diminished thrombin-induced IL-8/CXCL8 release. Thrombin induced mTOR Ser2448 phosphorylation and p70S6K Thr389 phosphorylation in a time-dependent manner. Moreover, rapamycin attenuated thrombin-stimulated p70S6K phosphorylation. We also found that transfection of cells with the dominant negative mutant of Akt (Akt DN) reduced the thrombin-induced increase in mTOR phosphorylation and p70S6K phosphorylation. Moreover, thrombin-stimulated p300 phosphorylation was attenuated by Akt DN, rapamycin, and p70S6K siRNA. Thrombin triggered p70S6K translocation from the cytosol to the nucleus in a time-dependent manner. Thrombin induced the complex formation of p70S6K, p300, and p65; acetylation of p65 Lys310, and recruitment of p70S6K, p300, and p65 to the κB-binding site of the IL-8/CXCL8 promoter region. In conclusion, these results indicate that thrombin initiates the Akt-dependent mTOR/p70S6K signaling pathway to promote p300 phosphorylation and NF-κB activation and finally induces IL-8/CXCL8 release in human lung epithelial cells.

The effects of power on–off durations of pulsed ultrasound on the destruction of cancer cells

PURPOSE

Low-intensity ultrasound irradiation is a potential method for suppressing cancer cell proliferation, inducing apoptosis and delivering specific cytotoxic genes or drugs into tumors topographically in future cancer therapies. However, ultrasound attenuates rapidly in tissue and produces heat. Pulsed ultrasound is frequently used to minimize pain and possible thermal damage to the surrounding normal tissue during therapy, since it results in smaller temperature increases. This study compared three pulsed-ultrasound strategies for destroying cancer cells, measuring their induced temperature increases to determine the optimal pulsing parameters.

MATERIALS AND METHODS

We performed three types of experiment, involving ultrasound with (1) a fixed duty cycle of 50% with variable on- and off-times, (2) a fixed off-time with variable on-times, and (3) a fixed on-time with variable off-times.

RESULTS

The results show that for different types of cultured cells (HeLa, HT-29, Ca9-22 and fibroblast) exposed to ultrasound of the same frequency (1 MHz) and energy, long pulses combined with off-times that are 5-10 times longer (on-/-off-times pairs of 5/25, 25/250, or 250/2500 ms/ms) cause significant cell destruction whilst avoiding temperature increases of more than 1.5 degrees C. Furthermore, the correlation between the temperature increase and the percentage of surviving cells is low.

CONCLUSIONS

Pulsed ultrasound with a long on-time and an even longer off-time exerts a high cytotoxic effect but a smaller temperature increase compared with non-pulsed ultrasound. This indicates that the cytotoxic effects observed in the current study were not purely due to the thermal effects of the ultrasound.

Crystalline style and tissue redistribution in Perna viridis as indicators of Cu and Pb bioavailabilities and contamination in coastal waters

The concentrations of Cu, Pb, and Zn in the crystalline style (CS) and in the remaining soft tissues (ST) of the green-lipped mussel Perna viridis from 10 geographical sites along the coastal waters off peninsular Malaysia were determined. The CS, compared with the remaining ST, accumulated higher levels of Cu in both contaminated and uncontaminated samples, indicating that the style has a higher affinity for the essential Cu to bind with metallothioneins. The similar pattern of Cu accumulation in the different ST of mussels collected from clean and Cu-contaminated sites indicated that the detoxification capacity of the metallothioneins had not been overloaded. For Pb, higher levels of the metal in the CS than in the remaining ST were found only in mussels collected from a contaminated site at Kg. Pasir Puteh. This indicated a tissue redistribution of Pb due to its binding to metallothioneins for Pb detoxification and the potential of the CS as an indicator organ of Pb bioavailability and contamination. For Zn, the above two phenomena were not found since no obvious patterns were observed (lower levels of Zn in the CS than in the remaining ST) in contaminated and uncontaminated samples due to the mechanism of partial regulation. Generally, all the different STs studied (foot, mantle, gonad, CS, gill, muscle, and byssus) are good biomonitoring tissues for Cu and Pb bioavailabilities and contamination. Among these organs, the CS was found to be the best organ for biomonitoring Cu. The present data also suggest the use of the tissue redistribution of Pb in P. viridis as an indicator of Pb bioavailability and contamination in coastal waters.

Enhanced activity and stability of a Cu/SiO2 catalyst for the reverse water gas shift reaction by an iron promoter

An Fe promoter inhibits the sintering of Cu particles and oxidation of the Cu surface, resulting in high catalyst activity and stability.

Performance characteristics of a regenerative catalytic oxidizer for treating VOC-contaminated airstreams

A pilot apparatus of a regenerative catalytic oxidizer (RCO) equipped with two electrical heaters and two 20-cm i.d. x 200-cm height regenerative beds was used to treat methyl ethyl ketone (MEK) and toluene, respectively, in an airstream. The regenerative beds were packed with gravel (approximate particle size 1.25 cm, specific area 205 m2/m3, and specific heat capacity 840 J/kg degree C) as a solid regenerative material and K-type thermal couples for measuring solid and gas temperatures, respectively. The catalyst bed temperature was kept around 400 degrees C and the gas superficial velocity was operated at 0.234 m/sec. This investigation measured and analyzed distributions of solid and gas temperatures with operating time and variations of volatile organic compound (VOC) concentrations in the regenerative beds. The overall VOC removal efficiency exceeded 98% for MEK and 95% for toluene. Degradation of VOCs will exist for MEK on the surface of solid material (gravel) in the temperature range of 330-400 degrees C, but toluene does not exhibit this phenomenon.

Cellular glutathione peroxidase protects mice against lethal oxidative stress induced by various doses of diquat

This study was to determine if cellular glutathione peroxidase (GPX1) protects against acute oxidative stress induced by diquat. Lethality and hepatic biochemical indicators in GPX1 knockout mice [GPX1(-/-)] were compared with those of wild-type mice (WT) after an intraperitoneal injection of diquat at 6, 12, 24, or 48 mg/kg of body weight. Although the WT survived all the doses, the GPX1(-/-) survived only 6 mg diquat/kg and were killed by 12, 24, and 48 mg diquat/kg at 52, 4.4 and 3.9 hr, respectively. Compared with those of surviving mice that were sacrificed on Day 7, the dead GPX1(-/-) had diquat dose-dependent increases (P < 0.05) in plasma alanine aminotransferase (ALT) activities. The GPX1(-/-) also had higher (P < 0.05) liver carbonyl contents than those of the WT, but the differences were irrespective of diquat doses. Whereas hepatic total GPX and phospholipid hydroperoxide glutathione peroxidase activities or hepatic GPX1 protein was not significantly affected by the diquat treatment, liver thioredoxin reductase and catalase activities were lower (P < 0.05) in the GPX1(-/-) injected with 12 mg diquat/kg than those of other groups. In conclusion, normal GPX1 expression is necessary to protect mice against the lethality, hepatic protein oxidation, and elevation of plasma ALT activity induced by 12-48 mg diquat/kg.

High levels of dietary vitamin E do not replace cellular glutathione peroxidase in protecting mice from acute oxidative stress

Our objective was to determine whether high levels of dietary vitamin E replaced the protection of the Se-dependent cellular glutathione peroxidase (GPX1) against paraquat- or diquat-induced acute oxidative stress in mice. Two experiments were conducted using GPX1 knockout [GPX1(-/-)] mice and wild-type (WT) mice (n = 78/group). In Experiment 1, mice were fed torula yeast-based, Se-adequate (0.4 mg/kg as sodium selenite) diets + 0, 75, 750 or 7,500 mg all-rac-alpha-tocopheryl acetate for 5 wk before an intraperitoneal injection of 50 mg paraquat/kg body weight. In Experiment 2, mice were fed the diet + 0 or 750 mg all-rac-alpha-tocopheryl acetate for 5 wk and were killed 1 or 3 h after an injection of diquat at 12, 24 or 48 mg/kg. In Experiment 1, all mice died of the injection and there were 8- to 15-fold differences (P < 0.001) in survival times between the GPX1(-/-) and the WT mice. Although increasing tocopheryl acetate from 0 to 750 mg/kg extended the survival time of the GPX1(-/-) mice for 2 h (P = 0.06), the highest tocopheryl acetate level resulted in a decrease (P < 0.05) in survival time in the WT mice. The vitamin E-deficient GPX1(-/-) mice had the highest concentration of hepatic thiobarbituric acid reacting substances. In Experiment 2, the diquat-induced formation of hepatic F(2)-isoprostanes was accelerated (P < 0.05) by vitamin E deficiency and was also affected by the GPX1 knockout. Diquat produced much greater (P < 0.01) dose-dependent increases in plasma alanine transaminase (ALT) activities in the GPX1(-/-) than in the WT mice. Hepatic phospholipid hydroperoxide GPX activities were decreased (P < 0.05) by the diquat injection only in the vitamin E-deficient GPX1(-/-) mice. Despite a potent inhibition of hepatic lipid peroxidation, high levels of dietary vitamin E do not replace the protection of GPX1 against the paraquat-induced lethality or the diquat-induced plasma ALT activity increase in mice.

Knockout of cellular glutathione peroxidase gene renders mice susceptible to diquat-induced oxidative stress

Two experiments were conducted to determine the protection and the underlying mechanisms of cellular glutathione peroxidase (GPX1) against lethal, acute oxidative stress induced by an intraperitoneal injection of 24 mg diquat/kg body weight. In experiment 1, mortality and survival times were compared among selenium (Se)-adequate or deficient GPX1 knockout mice [GPX1(-/-)] and wild-type mice (WT). In experiment 2, mice from these four groups were euthanized at 0, 1, 2, and 3 h after the injection of diquat to elucidate the time course of oxidative events. The stress produced 100% mortality in all of the groups except for the Se-adequate WT, which were euthanized on day 7 for analysis. The Se-deficient WT and the Se-adequate GPX1(-/-) had similar survival times (4.1 and 3.9 h), which were longer (p < .05) than that of the Se-deficient GPX1(-/-) (2.4 h). However, these three GPX1-deficient groups had higher levels (p < .05) of hepatic F2-isoprostanes and carbonyl contents and/or plasma alanine aminotransferase activities than those of the Se-adequate WT. The diquat-induced formations of hepatic F2-isoprostanes in these animals peaked at 1 h and preceded the rise of plasma alanine aminotransferase in the Se-adequate GPX1(-/-). Responses of hepatic superoxide dismutase activities to the diquat treatment were affected by the GPX1 level. In conclusion, GPX1 is the major selenoprotein to protect mice against the lethal oxidative stress induced by diquat.

Sugars modulate an unusual mode of control of the cell-wall invertase gene (Incw1) through its 3' untranslated region in a cell suspension culture of maize

We show here that a cell-wall invertase encoded by the Incw1 gene is regulated at both the transcriptional and posttranscriptional levels by sugars in a heterotrophic cell suspension culture of maize. The Incw1 gene encoded two transcripts: Incw1-S (small) and Incw1-L (large); the size variation was attributable to different lengths in the 3' untranslated region. Both metabolizable and nonmetabolizable sugars induced Incw1-L RNA apparently by default. However, only the metabolizable sugars, sucrose and D-glucose, were associated with the increased steady-state abundance of Incw1-S RNA, the concomitant increased levels of INCW1 protein and enzyme activity, and the downstream metabolic repression of the sucrose synthase gene, Sh1. Conversely, nonmetabolizable sugars, including the two glucose analogs 3-O-methylglucose and 2-deoxyglucose, induced greater steady-state levels of the Incw1-L RNA, but this increase did not lead to either an increase in the levels of the INCW1 protein/enzyme activity or the repression of the Sh1 gene. We conclude that sugar sensing and the induction of the Incw1 gene is independent of the hexokinase pathway. More importantly, our results also suggest that the 3' untranslated region of the Incw1 gene acts as a regulatory sensor of carbon starvation and may constitute a link between sink metabolism and cellular translation in plants.

Dietary intrinsic phytate protects colon from lipid peroxidation in pigs with a moderately high dietary iron intake

High iron consumption has been proposed to relate to an increase in the risk of colon cancer, whereas high levels of supplemental sodium phytate effectively reduce iron-induced oxidative injury and reverse iron-dependent augmentation of colorectal tumorigenesis. However, the protective role of intrinsic dietary phytate has not been determined. In this study, we examined the impact of removing phytate present in a corn-soy diet by supplemental microbial phytase on susceptibility of pigs to the oxidative stress caused by a moderately high dietary iron intake. Thirty-two weanling pigs were fed the corn-soy diets containing two levels of iron (as ferrous sulfate, 80 or 750 mg/kg diet) and microbial phytase (as Natuphos, BASF, Mt. Olive, NJ, 0 or 1200 units/kg). Pigs fed the phytase-supplemented diets did not receive any inorganic phosphorus to ensure adequate degradation of phytate. After 4 months of feeding, liver, colon, and colon mucosal scrapings were collected from four pigs in each of the four dietary groups. Colonic lipid peroxidation, measured as thiobarbituric acid reacting substances (TBARS), was increased by both the high iron (P< 0.0008) and phytase (P< 0.04) supplementation. Both TBARS and F2-isoprostanes, an in vivo marker of lipid peroxidation, in colonic mucosa were affected by dietary levels of iron (P< 0.03). Mean hepatic TBARS in pigs fed the phytase-supplemented, high iron diet was 43%-65% higher than that of other groups although the differences were nonsignificant. Moderately high dietary iron induced hepatic glutathione peroxidase activity (P= 0.06) and protein expression, but decreased catalase (P< 0.05) in the colonic mucosa. In conclusion, intrinsic phytate in corn and soy was protective against lipid peroxidation in the colon associated with a moderately high level of dietary iron.

Technology development in breath microanalysis for clinical diagnosis

A new generation of breath tests detects trace amounts of endogenous volatile organic compounds (VOCs) present in the breath. The breath microanalysis is potentially fast and convenient. It opens up a new promising area of using the breath test as a noninvasive diagnostic tool for a variety of diseases. Recent developments in microanalysis technology are expected to greatly facilitate the use of the breath test in clinical evaluations and applications, and these developments are described in the present review.

Cellular glutathione peroxidase is the mediator of body selenium to protect against paraquat lethality in transgenic mice

The antioxidative role of Se-dependent cellular glutathione peroxidase (EC 1.11.1.9, GPX1) in vivo has not been established. Our objective was to determine the effects of GPX1 knockout or overexpression on the susceptibility of mice to paraquat toxicity and the contributions of GPX1, compared with other selenoproteins and vitamin E, to body defenses against such acute oxidative stress. Four experiments were conducted using 111 GPX1 knockout or overexpressing mice and the respective controls. Mice were fed diets supplemented with Se (as sodium selenite) at 0-0.4 mg/kg and/or all-rac-alpha-tocopheryl acetate at 0-75 mg/kg before intraperitoneal injections of 12.5, 50 or 125 mg paraquat/kg body weight. All mice that received 50 or 125 mg paraquat/kg died spontaneously, and the survival time of mice was (independent of dietary levels of Se per se or alpha-tocopheryl acetate) solely a function of tissue GPX1 activity (P < 0.001). Severe acute pulmonary interstitial necrosis was found only in the GPX1 overexpressing mice and the controls that had extended survival time. Thiobarbituric acid reacting substances in postmortem liver inversely correlated with the tissue GPX1 activity and dietary levels of Se and/or alpha-tocopheryl acetate. In contrast, all mice that received 12.5 mg paraquat/kg survived and were killed 2 wk after the injection for tissue collection. Compared with the saline injection, this low dose of paraquat resulted in greater (P < 0.001) liver and lung F2-isoprostanes in both the GPX1 knockout mice and the controls. However, there was no difference in plasma alanine transaminase (EC 2.6.1.2) activity or overt injuries in liver, lung and kidney in either group. Our data indicate that GPX1 is the major, if not the only, metabolic form of body Se that protects mice against the lethal oxidative stress caused by high levels of paraquat; it seems less important, however, in protecting mice against the moderate oxidative stress by the low level of paraquat.

Knockout of cellular glutathione peroxidase affects selenium-dependent parameters similarly in mice fed adequate and excessive dietary selenium

This study was to determine whether or not effects of the cellular glutathione peroxidase (GPX1) knockout on several Se-dependent parameters in mice were tissue, dietary Se concentration, and selenoprotein specific. A 2 x 3 factorial experiment was conducted with 18 GPX1 knockout mice [GPX1(-)] and 18 controls (3 weeks old, half males and females). These mice were fed a torula yeast diet supplemented with all-rac-alpha-tocopheryl acetate (50 mg/kg of feed) and Se (sodium selenite) at 0, 0.5, or 3.0 mg/kg of feed for 6 weeks. Both kidney GPX1 mRNA levels and liver, kidney, lung, and testis total GPX activities, assayed using hydrogen peroxide, were affected (p < 0.001) by the GPX1 knockout and dietary Se concentrations, whereas kidney extracellular or plasma GPX (GPX3) mRNA levels and phospholipid hydroperoxide GPX (GPX4) activities in the four tissues were affected (p < 0.001) by only dietary Se concentrations. Total GPX activity in testis was reduced approximately 90% (p < 0.01) by the GPX1 knockout. Neither the GPX1 knockout nor the dietary Se concentrations affected mRNA levels of GPX4 in testis or selenoprotein P in kidney. Total liver Se concentrations were not different between the GPX1(-) and control mice at 0 mg Se/kg of feed, but were reduced (p < 0.01) by 61 and 64% in the GPX1(-) mice at 0.5 and 3.0 mg Se/kg of feed, respectively. These results not only confirm the independent expression of GPX3, GPX4, and selenoprotein P from that of GPX1, but also show similar effects of the GPX1 knockout on Se-dependent parameters in mice between different dietary Se concentrations, tissues, and selenoproteins.

Dietary selenium supplementation is required to support full expression of three selenium-dependent glutathione peroxidases in various tissues of weanling pigs

The current dietary allowance for selenium (Se) for pigs does not consider Se requirements for expression of several newly discovered Se-dependent enzymes and has raised environmental concerns. Our objective was to determine dietary Se requirements of young pigs for the full expression of cellular (GPX1), plasma (GPX3) and phospholipid hydroperoxide (GPX4) glutathione peroxidases. In Experiment 1, 18 weanling male pigs (4 wk old) were fed a corn-soybean meal basal diet (BD, 0.03 mg Se/kg) with the addition of 0, 0.1 or 0.3 mg Se/kg (Na2SeO3). In Experiment 2, 24 weanling barrows (6 wk old) were fed a similar BD with the addition of 0, 0.2, 0.3 or 0.5 mg Se/kg. Both experiments lasted for 5 wk. Pigs fed the BD had lower (P < 0.05) tissue GPX1 and GPX4 activities, plasma GPX activity, and(or) plasma Se concentrations than those fed the Se-supplemented diets. In Experiment 1, GPX1 and GPX4 activities in liver, heart and lung were lower (P < 0.05) in pigs fed 0.1 mg Se/kg than in those fed 0.3 mg Se/kg, although no such differences existed in thyroid or pituitary. Pigs fed 0.1 mg Se/kg also had lower (P < 0.05) plasma GPX3 activity at wk 5 and higher (P < 0.05) hepatic glutathione S-transferase activity than pigs fed 0.3 mg Se/kg. In Experiment 2, GPX1 and GPX4 activities in liver and heart, GPX1 and GPX4 mRNA levels in liver and GPX3 activity in plasma exhibited plateaus at 0.2 mg Se/kg. Pigs fed the BD had greater concentrations of F2-isoprostanes (a marker of in vivo lipid peroxidation) than those fed 0.2 mg Se/kg in plasma (P < 0.03) and liver (P < 0.04). We conclude that supplemental Se at 0.2 mg Se/kg of diet is required to support the full expression of three Se-dependent glutathione peroxidases in young pigs.

Cellular glutathione peroxidase knockout mice express normal levels of selenium-dependent plasma and phospholipid hydroperoxide glutathione peroxidases in various tissues

Selenium-dependent cellular glutathione peroxidase (GPX1) knockout [GPX1(-)] mice were derived from 129/SVJ x C57BL/6 hybrid mice by microinjecting C57BL/6 blastocysts with recombinant embryonic stem cells carrying a target mutation in the GPX1 gene. Experiment 1 was conducted to determine the effects of the GPX1 knockout on the susceptibility of mice to dietary vitamin E and Se deficiency and on the expression of the Se-dependent plasma glutathione peroxidase (GPX3) and phospholipid hydroperoxide glutathione peroxidase (GPX4), and the Se-independent glutathione S-transferase (GST). Eleven GPX1(-) and 11 control mice (5 wk old, six males and five females) were fed a Se-deficient, Torula yeast basal diet (0.02 mg Se/kg, no supplemental vitamin E) or the basal diet supplemented with 0.5 mg Se/kg (as Na2SeO3) for 13 wk. Experiment 2 was conducted to determine the effect of the GPX1 knockout on the total Se concentration in the liver of Se-adequate mice. Six GPX1(-) and four control mice (5 wk old, half males and females) were fed the basal diet supplemented with 0.2 mg Se/kg and 15 mg of all-rac-alpha-tocopheryl acetate/kg for 5 wk. There was no difference in body weight gain or apparent susceptibility to dietary vitamin E and Se deficiency between the GPX1(-) and control mice. Knockout of GPX1 resulted in almost complete abolishment of GPX1 activity in various tissues, but had no effect on the GPX3 or GPX4 mRNA level and activity or the GST activity in several tissues at either level of dietary Se. The liver total Se concentration in the Se-adequate GPX1(-) mice was only 42% of that in the controls (P < 0. 0001). These results indicate that GPX1 is expressed independently of GPX3 or GPX4 and represents approximately 60% of the total hepatic Se in Se-adequate mice.

Screening of biofiltering material for VOC treatment

Screening of biofiltering material for treatment of volatile organic compounds was performed by using a gas stream containing methyl ethyl ketone (MEK) as a target pollutant. Filtering media (FM) for screening were prepared by blending compost (such as pig and cow manure) and filling material (such as fern chips, wheat bran, and bagasse). Results show that a blend of pig manure/fern chips = 9:1 (wt basis) was superior with respect to the stability of the pH and the water-holding capacity of the FM and in the capacity for treating the target compound. Complete removal of the target compound was obtained at an organic loading of 100 g per cubic meter of filtering media per hour. By using the screened FM for treating MEK and toluene, long-term stability (> 1,200 hours) and complete removal can be obtained at an organic loading of 50 g per cubic meter of FM per hour for either compound.

Overexpression of cellular glutathione peroxidase does not affect expression of plasma glutathione peroxidase or phospholipid hydroperoxide glutathione peroxidase in mice offered diets adequate or deficient in selenium

Selenium-dependent cellular glutathione peroxidase (GPX1) overexpressing [GPX1(+)] mice were derived by microinjecting a 5.3-kb cloned entire mouse GPX1 genomic DNA into fertilized eggs. The objective of this study was to determine the effect of GPX1 overexpression and dietary selenium on the expression of selenoperoxidases and the status of lipid peroxidation of these transgenic animals. An experiment with a 2 x 2 factorial arrangement of treatments with 15 GPX1(+) and 15 control mice (2 mo old) was conducted for 8 wk. Ten mice of each group (half males and females) were fed a Se-deficient, Torula yeast basal diet (0.02 mg Se/kg, no supplemental vitamin E) and five mice (three males and two females) were fed the basal diet supplemented with 0.51 mg Se/kg as Na2SeO3. The GPX1(+) mice had greater GPX1 activities (one- to sixfold, P < 0.0001) than the control mice at both levels of dietary selenium in all tissues except for liver, in which such difference (100%, P < 0.05) was observed only in Se-deficient mice. The GPX1 mRNA level in kidney and in lung of the Se-deficient GPX1(+) mice was 81% and 7.5-fold greater (P < 0.003) than the respective control level. Overexpression of GPX1 did not alter phospholipid hydroperoxide glutathione peroxidase (GPX4) activities and mRNA levels or glutathione S-transferase (GST) activities in most of the tissues, plasma glutathione peroxidase (GPX3) activity or plasma Se concentrations. No differences in lipid peroxidation in kidney, lung or intestine were observed between the Se-deficient GPX1(+) and control mice. In conclusion, the overexpression of the GPX1 gene in these mice was tissue specific and did not affect the expression of GPX3, GPX4 or GST and plasma Se levels; dietary Se appeared to affect the GPX1 overexpression at its mRNA level.

Studies on epoxy compound fixation

Bioprostheses derived from collagenous tissues have to be fixed and subsequently sterilized before they can be implanted in humans. Clinically, the most commonly used fixative is glutaraldehyde. However, the tendency for glutaraldehyde to markedly alter tissue stiffness and promote tissue calcification are well-recognized drawbacks of this fixative. To address the deficiencies with the glutaraldehyde-fixed tissue, a new fixative, epoxy compound, was used to fix biological prostheses. The study was undertaken to investigate the fixation rates and crosslinking densities of biological tissues fixed with various epoxy compounds. These epoxy compounds are different in their chemical structures. Glutaraldehyde was used as a control. The fixation rates and crosslinking densities of the fixed tissues were determined by measuring their fixation indices and denaturation temperatures, respectively. Generally, the epoxy-fixed tissues were more pliable than the glutaraldehyde-fixed one. Furthermore, the tissues fixed with monofunctional epoxy compound were more pliable than those fixed with multifunctional epoxy compounds. With increasing pH or temperature, the fixation rate of epoxy compound increased. However, the number of epoxide functional groups did not seem to affect the fixation rate of the epoxy compound. The fixation rate of glutaraldehyde was faster than that of epoxy compounds. Additionally, the crosslinking density of the glutaraldehyde-fixed tissue was greater than that of the epoxy-fixed counterparts. Moreover, it was noted that the denaturation temperatures of the tissues fixed with glutaraldehyde or multifunctional epoxy compounds were significantly higher than the fresh ones (p < 0.05), while that fixed with monofunctional epoxy compound stayed roughly the same throughout the entire fixation process (p > 0.05). The results obtained in this study may be used to optimize the fixation process for developing bioprostheses fixed with epoxy compounds.

Critical evaluation of results of extension of indication for surgery for primary bronchogenic carcinoma

Among 3,120 surgically resected cases (1957-1983) in Shanghai Chest Hospital, 1,476 resections (47.3%) were performed under extended indication. Six categories--(1) aged 70-87 years (102), (2) associated with severe impairment of pulmonary function (25), (3) small-cell anaplastic type (143), (4) stage III lesion (1,145), (5) invading carina (29), (6) with disseminated pleural metastasis and effusion (32)--were critically evaluated. For the first four categories, long-term survival rates were very encouraging, whereas only technical advancement and short-term results were discussed for the last two. The authors present strategic points significant in availing higher overall operability and hence the overall survival rate, shedding light on the increase of curative potential for lung cancer.

A theoretical description of phase diagrams for nonideal lipid mixtures

A theoretical description of phase diagrams for nonideal lipid mixtures is presented. The phase diagrams in this model are constructed by a quasi-chemical approach for the calculations of enthalpies of the regular solutions and by van der Waals attractive energy of lipids which described the degree of nonideality in the solid and fluid phases. The results of theoretical calculations of phase diagrams for dimyristoyl phsophatidylcholine/dipalmitoyl phosphatidylcholine dimyristoyl phosphatidylcholine/distearoyl phosphatidylcholine, and dipalmitoyl phosphatidylcholine/distearoyl phosphatidylcholine mixtures are in good agreement with experimental data.

A theoretical model for lipid mixtures, phase transitions, and phase diagrams

We present a new model for the thermodynamic properties of lipid bilayers. The model consists of a system of hard cylinders of varying radii that correspond to the different molecular radii of lipids having different numbers of gauche rotations in their chains. Scaled particle theory is used to provide an accurate estimate of the entropy of packing of the cylinders. To apply the model to bilayers we introduce a semiempirical attractive potential energy. Once the form of this potential is chosen, we adjust one parameter, the interaction strength, so that the model fits the transition temperatures and entropies for various phospholipids. The model then agrees quite well with other published data for these systems. We also directly generalize our model to lipid mixtures, and we obtain phase diagrams that we compare to existing data for these systems. We use the model to describe lipid protein interactions in bilayers as well.