Unsupervised Approach for the Identification of the Predominant Site of Upper Airway Collapse in Obstructive Sleep Apnoea Patients Using Snore Signals.

Knowledge regarding the site-of-collapse in the upper airway in obstructive sleep apnoea (OSA) has implications for treatment options and their outcomes. However, current methods to identify the site-of-collapse are not suitable for clinical practice due to the invasive nature, the time/cost of the tests and the inconsistency of the obstruction site identified with natural and drug-induced sleep. In this study, we adopted an unsupervised algorithm to identify the predominant site-of-collapse of the upper airway during natural sleep using nocturnal audio recordings. Nocturnal audio was recorded together with full-night polysomnography using a ceiling microphone. Various acoustic features of the snore signal during hypopnoea events were extracted. We developed a feature selection algorithm combining silhouette analysis with the Laplacian score algorithm to select the high performing features. A k-means clustering model was developed to form clusters using the features extracted from snore data and analyse the correlation between the clusters generated and the predominant site-of-collapse. Cluster analysis showed that the data tends to fit well in two clusters with a mean silhouette coefficient of 0.79 and with an accuracy of 68% for classifying tongue/non-tongue collapse. The results indicate a correlation between snoring and the predominant site-of-collapse. Therefore, it could potentially be used as a practical, non-invasive, low-cost diagnosis tool for improving the selection of appropriate therapy for OSA patients without any additional burden to the patients undergoing a sleep test.

Association of snoring characteristics with predominant site of collapse of upper airway in obstructive sleep apnea patients.

STUDY OBJECTIVES: Acoustic analysis of isolated events and snoring by previous researchers suggests a correlation between individual acoustic features and individual site of collapse events. In this study, we hypothesized that multiparameter evaluation of snore sounds during natural sleep would provide a robust prediction of the predominant site of airway collapse. METHODS: The audio signals of 58 obstructive sleep apnea patients were recorded simultaneously with full-night polysomnography. The site of collapse was determined by manual analysis of the shape of the airflow signal during hypopnea events and corresponding audio signal segments containing snore were manually extracted and processed. Machine learning algorithms were developed to automatically annotate the site of collapse of each hypopnea event into three classes (lateral wall, palate, and tongue base). The predominant site of collapse for a sleep period was determined from the individual hypopnea annotations and compared to the manually determined annotations. This was a retrospective study that used cross-validation to estimate performance. RESULTS: Cluster analysis showed that the data fit well in two clusters with a mean silhouette coefficient of 0.79 and an accuracy of 68% for classifying tongue/non-tongue collapse. A classification model using linear discriminants achieved an overall accuracy of 81% for discriminating tongue/non-tongue predominant site of collapse and accuracy of 64% for all site of collapse classes. CONCLUSIONS: Our results reveal that the snore signal during hypopnea can provide information regarding the predominant site of collapse in the upper airway. Therefore, the audio signal recorded during sleep could potentially be used as a new tool in identifying the predominant site of collapse and consequently improving the treatment selection and outcome.

mRNA Expression Analysis of E-Cadherin, VEGF, and MMPs in Gastric Cancer: a Pilot Study.

Gastric cancer (GC) is a serious fatal cancer on a global scale because of its presentation at advanced stage. The expressions of vascular endothelial growth factor (VEGF), E-cadherin, and matrix metalloproteinases (MMPs) in other cancers have been reported. However, its expression and underlying mechanisms are little known in gastric cancer in Indian context. In this study, we detected mRNA expression of VEGF, E-cadherin, and MMPs (MMP-1, MMP-2, and MMP-9) in 73 gastric cancer tissues and 27 normal controls by reverse-transcriptase polymerase chain reaction (RT-PCR). Receiver operator characteristics analysis was done for determining the diagnostic utility of VEGF, MMPs and E-cadherin with respect to the sensitivity and specificity. The association of VEGF, MMPs, and E-cadherin expression with the clinicopathological characteristics and the prognosis was subsequently analyzed. The mRNA expression results showed that E-cadherin was significantly downregulated in 47.9% of GC in comparison to control. There was no change in VEGF expression observed in 90.4% GC cases. MMP-1, MMP-2, and MMP-9 were overexpressed in 13.7%, 28.8%, and 11% of GC, respectively, with significant change in MMP-2 (p ≤ 0.0001) and MMP-9 (p = 0.027) in comparison to control. Our results strengthen the necessity of more studies to elucidate the prophetic role of these genes in the development of gastric cancer.

Identifying the Predominant Site of Upper Airway Collapse in Obstructive Sleep Apnoea Patients Using Snore Signals.

Knowledge regarding the site of airway collapse could help in choosing an appropriate structure-specific or individualized treatment for obstructive sleep apnoea (OSA). We investigated if the audio signal recorded during hypopnoea (partial obstruction) events can predict the site-of-collapse of the upper airway. In this study, we designed an automatic classifier that predicts the predominant site of upper airway collapse for a patient as "lateral wall", "palate", "tongue-based" related collapse or "multi-level" site-of-collapse by processing of the audio signal. The probable site-of-collapse was determined by manual analysis of the shape of the airflow signal during hypopnoea, which has been reported to correlate with the site of collapse. Audio signal was recorded simultaneously with full-night polysomnography during sleep with a ceiling microphone. Various time and frequency features of the audio signal were extracted to classify the audio signal into lateral wall, palate and tongue-base related collapse. We introduced an unbiased process using nested leave-one patient-out cross-validation to choose the optimal features. The classification was carried out with a multi-class linear discriminant analysis classifier. Performance of the proposed model showed that our automatic system can achieve an overall accuracy of 65% for determining the predominant site-of-collapse for all site-of-collapse classes and an accuracy of 80% for classifying tongue/non-tongue related collapse. Our results indicate that the audio signal recorded during sleep can be helpful in identifying the site-of-collapse and therefore could potentially be used as a new tool for deciding appropriate treatment for OSA.

Characterisation of Upper Airway Collapse in OSA Patients Using Snore Signals: A Cluster Analysis Approach.

This paper provides the results of an unsupervised learning algorithm that characterize upper airway collapse in obstructive sleep apnoea (OSA) patients using snore signal during hypopnoea events. Knowledge regarding the site-of-collapse could improve the ability in choosing the most appropriate treatment for OSA and thereby improving the treatment outcome. In this study, we implemented an unsupervised k-means clustering algorithm to label the snore data during hypopnoea events. Audio data during sleep were recorded simultaneously with full-night polysomnography with a ceiling microphone. Various time and frequency features of audio signal during hypopnoea were extracted. A systematic evaluation method was implemented to find the optimal feature set and the optimal number of clusters using silhouette coefficients. Using these optimal feature sets, we clustered the snore data into two. Performance of the proposed model showed that the data fit well in two clusters with a mean silhouette coefficients of 0.79. Also, the clusters achieved an overall accuracy of 62% for predicting tongue/non-tongue related collapse.

Automated identification of the predominant site of upper airway collapse in obstructive sleep apnoea patients using snore signal.

OBJECTIVE: This study provides a novel approach for an automated system using a machine learning algorithm to predict the predominant site of upper airway collapse into four classes ('lateral wall', 'palate', 'tongue-base' related collapse or 'multi-level' site-of-collapse) in obstructive sleep apnoea (OSA) patients from the audio signal recorded during normal sleep. APPROACH: Snore sounds from 58 patients were recorded simultaneously with full-night polysomnography during sleep with a ceiling mounted microphone. The probable site-of-airway collapse was determined by manual analysis of the shape of the airflow signal during hypopnoea. Time and frequency features of the audio signal were extracted from each hypopnoea event to classify the audio signal into 'lateral wall', 'palate' and 'tongue-base' related collapse according to prior research. The data was divided into two sets. The Learning Set contained the data of the first 45 patients and was used for building the model. The Hidden Set contained the data from the remaining 13 patients and was used for testing the performance of the model. Feature selection was employed to boost the classification performance. The classification was carried out with a multi-class linear discriminant analysis classifier to classify the predominant site-of-collapse for a patient into the four classes. Performance was evaluated by comparing the automatic and manually labelled data based on the predominant site-of-collapse and calculating the accuracy. MAIN RESULTS: The model achieved an overall accuracy on the Hidden Set of 77% for discriminating tongue/non-tongue collapse and an accuracy of 62% accuracy for all site-of-collapse classes. SIGNIFICANCE: Our results demonstrate that the audio signal recorded during sleep can successfully identify the site-of-collapse in the upper airway. The additional information regarding the obstruction site may assist clinicians in deciding the most appropriate treatment for OSA.

A Preliminary Study of the Automatic Classification of the Site of Airway Collapse in OSA patients Using Snoring Signals.

In this study we investigated if audio signals may carry information related to the site of obstruction of the upper airway. The information regarding the site of collapse could improve obstructive sleep apnoea (OSA) treatment by allowing more individualized or structure-specific therapy. In this preliminary study, we developed an algorithm for automatically determining the site of collapse in 13 OSA patients through snoring analysis. Audio was recorded with a ceiling mounted microphone, simultaneously with full-night polysomnography during sleep. The surrogate measure of the site of airway collapse was identified by manual analysis of the nasal pressure signal. We extracted various time and frequency features of audio signal to classify the signal into "lateral wall", "palate" and "tongue base" related collapse. The classification was carried out with a Gaussian mixture model classifier. Performance of the proposed model showed that it can achieve an overall accuracy of 78.9±0.96% with specificity and PPV of (89.3±0.81%, 78±1.5%) (73.2±1.3% , 83.2±1.8%) (61.3±2.5%, 71.8±1.3%) for lateral wall, palate and tongue base related collapse respectively. Our preliminary results suggest that the audio signal may be helpful in identifying the site of obstruction and therefore maybe a useful tool for deciding appropriate therapy.

Retrieved Magnesia-Stabilized Zirconia Femoral Heads Exhibit Minimal Roughening and Abrasive Potential.

BACKGROUND: The degradation of ceramic femoral heads made of yttria-stabilized zirconia (Y-TZP) because of tetragonal-to-monoclinic phase transformation in vivo is well-described, whereas magnesia-stabilized zirconia (Mg-PSZ) ceramics resist phase transformation in a warm aqueous environment. The purpose of this study was to evaluate phase transformation, changes in surface topography, and roughness parameters, including changes in surface polarity and abrasiveness, among retrieved zirconia femoral heads. METHODS: A total of 69 Y-TZP and 86 Mg-PSZ-retrieved femoral heads were examined, with 5 never-implanted heads of each type as controls. Selected heads were scanned by x-ray diffraction, to measure % monoclinic phase. All heads were scanned by optical profilometry to find visual evidence of degradation and to measure surface roughness, surface polarity, and the functional roughness parameters. Monoclinic phase % and roughness data were plotted vs time in vivo. RESULTS: Visual evidence of phase transformation was observed among Y-TZP femoral heads, and some exhibited pitting. Y-TZP femoral heads roughened and become more abrasive in vivo, although those made by CeramTec exhibited less degradation than those by Morgan and Saint Gobain. In contrast, Mg-PSZ heads did not exhibit pitting, undergo phase transformation, or roughen in vivo, and retained a negative surface polarity. CONCLUSION: All Y-TZP femoral heads exhibited increased phase transformation with time in vivo, although not all Y-TZP heads exhibited catastrophic roughening. No phase transformation was observed on Mg-PSZ femoral heads after up to 19.2 years in vivo. The lack of degradation among Mg-PSZ retrievals suggests a lower wear potential in joint replacement.

A case of hepatic, renal and duodenal penetration by a Celect inferior vena caval filter.

Inferior vena caval (IVC) filters are used as a mechanical option for the treatment of venous thromboembolism (VTE) when standard anticoagulation therapy is either contraindicated or VTE recurs despite adequate anticoagulation. Filters are not without risk, however. Reported complications include filter migration and fracture of filter components, leading to IVC rupture and penetration into pericaval tissues (notably kidney, heart, pericardium, thoracic cavity, liver, bowel and aorta). Here we describe an extreme case of multiple organ penetration by a standard Celect caval filter.

Comment on: Conservative management of an infected laparoscopic hernia mesh: A case study.

INTRODUCTION: We recently published an article in this journal describing the successful conservative treatment of a patient with an infected laparoscopically inserted hernia mesh using gentamycin flushes via a pig-tail drain and long term oral antibiotics. This prevented the need for major reconstructive surgery. However, 3 months after we published our report, the patient re-presented with symptoms of a recurrence of infection. PRESENTATION OF CASE: Seven months after stopping oral antibiotics, our patient represented with fever and swelling and redness over his left sided inguinal hernia mesh. This mesh had to be surgically removed. The procedure was laparoscopic and showed infection confined to the central 5cm of the mesh. Microbiology culture results were the same as on initial presentation. DISCUSSION: The microbiology results suggest that it is likely that the infection was never fully eradicated and that our intervention merely kept the infection at bay. Once long term antibiotics were stopped it is likely that the infection was able to eventually recur. CONCLUSION: Consequently, we have been unable to show that our method of conservative management of infected hernia meshes is effective to prevent long term recurrence of infection.

Conservative management of an infected laparoscopic hernia mesh: A case study.

INTRODUCTION: A dreaded complication of laparoscopic hernia repair is infection of the mesh. Traditionally mesh infection is managed by surgical removal of the mesh, an extensive procedure resulting in high re-herniation rates. A technique to treat such infections whilst salvaging the mesh is sorely needed. We describe a case in which a laparoscopic mesh infection was treated solely with drainage, parenteral antibiotics and antibiotic irrigation of the mesh. PRESENTATION OF CASE: A 65 year old gentleman presented 11 months post laparoscopic repair of an inguinal hernia with malaise and an uncomfortable groin swelling. Computed tomography scanning revealed a collection surrounding the mesh which was drained and cultured to show heavy growth of Staphylococcus aureus. A pigtail drain on continuous drainage was inserted and kept in situ for 7 weeks. The patient received one week of intravenous flucloxacillin and two gentamycin irrigations through the drain as an inpatient. He then received 6 weeks of oral flucloxacillin and bi-weekly saline flushes through the drain in the community. By 12 weeks an ultrasound scan showed resolution of the collection. At 7 months he remains clinically free from recurrence. DISCUSSION: Here we report a novel conservative method used to treat a hernia mesh infection, preserve the mesh and avoid major surgery. Other reports exist suggesting variations in conservative methods to treat mesh infections, however ours is by far the most conservative. CONCLUSION: Clearly, further research is required to identify which method is most effective and in which patients it is likely to be successful.

AIRE1A might be involved in cyclin B2 degradation in testicular lysates.

The autoimmune regulator gene Aire shows predominant expression in thymus and other immunologically relevant tissues, and is assigned the major function of programming autoreactive T-cell deletion. However, the expression of this gene in tissues outside the immune system raises a question about its possible function beyond the T-cell deletion dogma. We detected Aire in mouse testis, and the expression of AIRE protein was remarkably high in postmeiotic germ cells. Sequencing results indicate that testis expressed Aire variant 1a. AIRE could be detected in spermatozoa, with heavy localization on the principal acrosomal domains. Mouse oocytes stained negatively for AIRE before fertilization, but stained positively for AIRE 30 min after fertilization. In the zygote, the levels of AIRE correlated negatively with cyclin B2 levels. Goat testicular lysates spiked with recombinant human AIRE exhibited augmented cyclin B2 degradation in the presence of protease inhibitors, which was inhibited by MG-132, indicating the operation of proteasomal pathways. Thus, this study identifies a correlation between the presence of AIRE and proteasomal breakdown of cyclin B2, which leads us to speculate that cyclin B2 could be a target of AIRE's E3-ubiquitin ligase activity.

Long-term outcomes of low-dose catheter-directed thrombolytic therapy: a 5-year single-center experience.

PURPOSE: To determine immediate and long-term outcomes following catheter-directed intraarterial thrombolysis of occluded native arteries and infrainguinal vein grafts by using low-dose tissue-type plasminogen activator (tPA) in patients with lower limb ischemia. MATERIALS AND METHODS: One hundred eleven intraarterial thrombolysis procedures were performed in 96 patients during the 2-year study period. Patient records were available for retrospective review in 85 thrombolytic procedures performed in 74 (77%) of the 96 patients. Forty-one native vessels (four iliac, 24 superficial/common femoral, and 13 popliteal/below-knee vessels), six iliac stents, and 38 infrainguinal vein grafts were treated by using a low-dose (0.5 mg/h recombinant tPA) catheter-directed thrombolytic regimen. Procedural success was based on angiographic and clinical outcomes, and the need for further reconstructive surgery or amputation was documented. RESULTS: Intraarterial thrombolysis was successful in 76%, was partially successful in 11%, and failed in 13%. Adjunctive angioplasty was performed in 33 of 55 patients (60%) with successful lysis, and immediate reconstructive surgery was required in five patients. There was one episode of puncture site bleeding and one gastrointestinal hemorrhage but no procedure-related deaths at 30 days. After a median follow-up of 6.5 years, 30 of the 55 patients (55%) who underwent successful thrombolysis required no further surgical intervention; however, further surgery was required in 45% of patients after a mean interval of 301 days (range, 2-1,344 days), including 10 (18%) amputations (six major and four minor). CONCLUSIONS: Low-dose intraarterial thrombolysis is safe and effective, delaying and dramatically reducing the need for surgical intervention in lower limb ischemia due to native vessel or infrainguinal graft occlusion.