Automatic assessment of blood pressure for Korotkoff sounds on the basis of human hearing threshold.

OBJECTIVE: In this study, to measure blood pressure (BP) on the basis of human hearing threshold, we proposed a method that detects the audible or inaudible Korotkoff sounds (K-sounds) using the equal loudness contour and automatically assesses the BP. METHODS: In this study, we detected the systolic period of K-sounds using cuff pressure oscillation and then converted the K-sounds corresponding to the systolic interval into sound pressure levels (SPLs). Next, the systolic blood pressure (SBP) and diastolic blood pressure (DBP) were assessed by mapping the K-sounds, which were converted into SPLs on an equal loudness contour. RESULTS: To validate the accuracy of our proposed method, we compared it with the auscultatory method. The mean differences (mean±SD) in the SBP and DBP were 0.31±1.95 and 1.20±2.17 mmHg, respectively. For the SBP, the linear regression equation was y=0.98x+1.56 mmHg (where x and y represent the auscultatory and the proposed method, respectively), with a SE of estimate of 1.93 mmHg and a correlation coefficient of 0.99. For the DBP, the linear regression equation was y=1.01x-1.94 mmHg, with an SE of estimate of 2.18 mmHg and a correlation coefficient of 0.98. All P values were less than 0.0001 for both regressions. CONCLUSION: The auscultatory method of BP monitoring is sensitive to the observer's condition or environmental noise. To overcome these disadvantages, we used the human hearing threshold for objective SBP and DBP automatic assessment, and this method can be applicable to an automatic auscultatory method.

Evaluation of masseter muscle electromyography after surgical extraction of third molar.

PURPOSE: The aims of this study were to evaluate the results of electromyographies (EMGs) of the masseter muscle after mandibular third molar surgery and to determine the relationships between clinical variables and EMG results. PATIENTS AND METHODS: Seventy patients were included in the study. The parameters of the patients' masseter muscles were measured using EMG prior to operation and 7 and 21 days post-operation. Clinical variables were also recorded before and after the third molar surgeries. RESULTS: When the masseter muscle EMG results from the tooth-extracted side were compared with those from the non-extracted (control) side, significant differences in the areas of voltage, power spectral densities and median frequencies (p = 0.011, 0.017 and 0.041, respectively) were found 7 days postoperatively. Additionally, there were significant associations between some clinical variables (i.e. postoperative swelling, bone reduction and pericoronitis) and the EMG results 7 days postoperatively, (p < 0.05). However, there were no significant differences 21 days postoperatively. CONCLUSION: This study revealed that the postoperative changes in EMG activities were transient. Although there have been controversies about the reliability of EMG, this study showed that some EMG variables could be used to evaluate postoperative changes in masseter muscle activity.

The Association between Symptoms of Autonomic Neuropathy and the Heart Rate Variability in Diabetics.

BACKGROUND: There are few tools to detect the diabetic autonomic neuropathy at an earlier stage. This study was conducted to investigate the association between symptoms of autonomic neuropathy and the heart rate variability (HRV) in diabetics. METHODS: Study subjects consisted of 50 diabetic patients and 30 outpatient hospital control patients at a university family medicine department. The patients completed a Korean version of composite autonomic symptom scale (COMPASS). Electrocardiography was recorded in the supine position, on standing, and during deep breathing, for 5 minutes each. HRV of frequency domain was calculated by power spectral analysis. RESULTS: The COMPASS score was higher in female diabetic patients compared with that in controls. Among 50 diabetic patients, the total COMPASS score correlated positively with normalized low frequency (LF) score (normalized units, n.u.) (r = 0.62, P < 0 .001) and low frequency/high frequency (LF/HF) (r = 0.77, P < 0.001), negatively with normalized HF score (n.u.) (r = -0.59, P < 0.001) and RMSSD (square root of the mean of the sum of the square of differences between adjacent NN interval; r = -0.33, P = 0.031). The decrease in LF (n.u) and the increase in HF (n.u) by deep breathing from the supine position were higher in diabetic patients compared with those in controls. The increase in LF (n.u) and the decrease in HF (n.u) by standing from the supine position were lower in diabetic patients compared with those in controls. CONCLUSION: The COMPASS score correlated with some component score of the HRV in diabetics. The HRV may be used as a tool to detect diabetic autonomic neuropathy by augmentation with position change.

Nonconstrained sleep monitoring system and algorithms using air-mattress with balancing tube method.

We evaluated the performance of a bed-type sensor system using the air-mattress with balancing tube (AMBT) method to noninvasively monitor the signals of heartbeat, respiration, and events of snoring, sleep apnea and body movement of subject on the system. The proposed system consists of multiple cylindrical air cells, two sensor cells and 18 support cells, and the small physiological signals were measured by the changes in pressure difference between the sensor cells, and the dc component was removed by balancing tube that is connecting the sensor cells. Using newly developed AMBT method, heartbeat, respiration, snoring, and body movement signals were clearly measured. For the concept of a home healthcare system, two automatic processing algorithms were developed: one is to estimate the mean heart and respiration rates for every 30 s, and another one is to detect the snoring, sleep apnea, and body movement events from the measured signals. In the beat-to-beat heart rate and breath-by-breath respiration rate analyses, the correlation coefficients of the heart and respiration rates from the proposed AMBT method compared with reference methods, electrocardiogram, and respiration effort signal from piezoelectric belt, were 0.98 ( p << 0.01) and 0.96 ( p << 0.01), respectively. Sensitivity and positive predictive value (PPV) of the detection algorithm for snoring event were 93%, 96%, for sleep apnea event were 93%, 88%, and for body movement event were 86%, 100%, respectively. These findings support that ABMT method provides an accurate and reliable means to monitor heartbeat, respiration activities and the sleep events during sleep.

Gene mutations of 23S rRNA associated with clarithromycin resistance in Helicobacter pylori strains isolated from Korean patients.

Although resistance of Helicobacter pylori to clarithromycin is a major cause of failure of eradication therapies, little information is available regarding gene mutations of clarithromycin-resistant primary and secondary H. pylori isolates in Korea. In the present study, we examined gene mutations of H. pylori 23S rRNA responsible for resistance to clarithromycin. DNA sequences of the 23S rRNA gene in 21 primary clarithromycin-resistant and 64 secondary clarithromycin-resistant strains were determined by PCR amplification and nucleotide sequence analyses. Two mutations of the 23S rRNA gene, A2143G and T2182C, were observed in primary clarithromycin-resistant isolates. In secondary isolates, dual mutation of A2143G+T2182C was frequently observed. In addition, A2143G+T2182C+ T2190C, A2143G+T2182C+C2195T, and A2143G+T2182C +A2223G were observed in secondary isolates. Furthermore, macrolide binding was tested on purified ribosomes isolated from T2182C or A2143C mutant strains with [14C]erythromycin. Erythromycin binding increased in a dose-dependent manner for the susceptible strain but not for the mutant strains. These results indicate that secondary isolates show a greater variety of 23S rRNA gene mutation types than primary isolates, and triple mutations of secondary isolates are associated with A2143G+T2182C in H. pylori isolated from Korean patients.

Nonlinear support vector machine visualization for risk factor analysis using nomograms and localized radial basis function kernels.

Nonlinear classifiers, e.g., support vector machines (SVMs) with radial basis function (RBF) kernels, have been used widely for automatic diagnosis of diseases because of their high accuracies. However, it is difficult to visualize the classifiers, and thus difficult to provide intuitive interpretation of results to physicians. We developed a new nonlinear kernel, the localized radial basis function (LRBF) kernel, and new visualization system visualization for risk factor analysis (VRIFA) that applies a nomogram and LRBF kernel to visualize the results of nonlinear SVMs and improve the interpretability of results while maintaining high prediction accuracy. Three representative medical datasets from the University of California, Irvine repository and Statlog dataset-breast cancer, diabetes, and heart disease datasets-were used to evaluate the system. The results showed that the classification performance of the LRBF is comparable with that of the RBF, and the LRBF is easy to visualize via a nomogram. Our study also showed that the LRBF kernel is less sensitive to noise features than the RBF kernel, whereas the LRBF kernel degrades the prediction accuracy more when important features are eliminated. We demonstrated the VRIFA system, which visualizes the results of linear and nonlinear SVMs with LRBF kernels, on the three datasets.

Vacuolating cytotoxin in Helicobacter pylori water-soluble proteins upregulates chemokine expression in human eosinophils via Ca2+ influx, mitochondrial reactive oxygen intermediates, and NF-kappaB activation.

Helicobacter pylori-infected gastric mucosa is characterized by infiltration of inflammatory cells such as neutrophils and eosinophils. However, little information is available on the relationship between H. pylori virulence factors and chemokine expression in eosinophils. This study investigates the role of vacuolating cytotoxin (VacA) in chemokine expression from human eosinophils. Eosinophils were isolated from the peripheral blood of healthy volunteers using a magnetic cell separation system. VacA(+) H. pylori water-soluble proteins (WSP) induced higher expression of interleukin-8, growth-related oncogene alpha, monocyte chemotactic protein 1, and RANTES (regulated on activation, normal, T-cell expressed and secreted) than Vac(-) WSP in human eosinophils, as assessed by quantitative reverse transcription-PCR and enzyme-linked immunosorbent assay. Purified VacA not only increased chemokine expression but also activated p65/p50 NF-kappaB heterodimers and phosphorylated IkappaB kinase (IKK) alpha/beta signals in human eosinophils. Inhibition of NF-kappaB and IKK significantly decreased the chemokine expression in VacA-stimulated eosinophils. Furthermore, VacA-induced NF-kappaB activation and chemokine release from eosinophils were dependent on Ca(2+) influx and mitochondrial generation of reactive oxygen intermediates (ROI). These results suggest that NF-kappaB and IKK signals via Ca(2+) influx and mitochondrial ROI play a role in the up-regulation of chemokine expression in eosinophils stimulated with H. pylori VacA.

A new approach for non-intrusive monitoring of blood pressure on a toilet seat.

Pulse arrival time (PAT) was measured non-intrusively to estimate each individual's blood pressure. Electrocardiogram (ECG) was measured with copper-coated electrodes and photoplethysmogram (PPG) was measured using a specially designed toilet seat apparatus. Non-intrusively measured PATs were compared with PATs measured by the standard method, and the results showed a good correlation. An equation was used to estimate blood pressure from the measured PAT during a training period for each individual. Estimated blood pressures were compared with measured blood pressures in a series of blood pressure varying experiments. For each individual, the estimated blood pressure was similar to the measured blood pressure within a tolerable error range. This method was also practiced for long-term monitoring, and the results show the value of this method for continuous home monitoring of blood pressure.