Intra-Oral Factors Influencing Halitosis in Young Women

OBJECTIVES: The aim of this research was to determine intra-oral factors that affect halitosis in young women. METHODS: This study was performed between March 2014 to May 2014, and included 35 women in their 20s with good oral health. Correlation and logistic regression analyses were performed to investigate the change in halitosis immediately, and 1 hour after scaling. RESULTS: In both oral gas (OG) and extraoral gas (EG) groups, halitosis was reduced after scaling compared to before scaling. The logistic regression analysis of oral state factors in OG showed that as oral fluid [odds ratio (OR) = 0.792, p = 0.045] and dental plaque (OR = 0.940, p = 0.016) decreased by 1 unit, the OR in the OG group decreased (> 50). In addition, as glucose levels in the oral cavity (OR = 1.245, p = 0.075) and tongue coating index (OR = 2.912, p = 0.064) increased by 1 unit, the OR in the OG group increased (> 50). Furthermore, in the EG group, as oral fluid (OR = 0.66, p = 0.01) and dental plaque (OR = 0.95, p = 0.04) decreased, the OR in the EG group decreased (> 50) significantly. CONCLUSION: To control halitosis, it is necessary to increase oral fluid and decrease the amount of tongue plaque. Furthermore, maintaining a healthy oral environment, aided by regular scaling and removal of dental plaque, may significantly control halitosis.

Biomarker for the Prediction of Major Adverse Cardiac Events in Patients with Non-ST-Segment Elevation Myocardial Infarction

N-terminal pro-brain natriuretic peptide (NT-proBNP) is a well-known biomarker for the diagnosis and prognosis of heart failure, and is directly associated with myocardial dysfunction. We evaluated the prognostic value of NT-proBNP for major adverse cardiac events (MACEs) among patients with non-ST-segment elevation myocardial infarction (NSTEMI) from the Korea Acute Myocardial Infarction Registry during their mid-term follow-up period. In this paper, we analyzed NT-proBNP according to various MACE and level of NT-proBNP. We used multivariate logistic regression to determine the risk factors according to MACE type and NT-proBNP levels, and to identify the cutoff value for each MACE by using the receiver operating characteristic (ROC) curve. NT-proBNP was a significant variable among cardiac deaths (p = 0.016), myocardial infarction (p = 0.000), and coronary artery bypass grafting (CABG) (p = 0.000) in patients with MACE compared with those without MACE. Two-vessel coronary artery disease (CAD) (p = 0.037) and the maximum creatinine kinase (max-CK) (p = 0.031) produced significant results in repeat percutaneous coronary intervention. The area under the ROC curve was found to be statistically significant for cardiac death and CABG. NT-proBNP is a useful predictor for 12-month MACEs among patients with NSTEMI and in those with heart failure. We propose that a new index incorporating NT-proBNP, max-CK, and CAD vessel will be useful as a prognostic indicator of MACEs in the future.

Erratum: Increased Expression of Herpes Virus-Encoded hsv1-miR-H18 and hsv2-miR-H9-5p in Cancer-Containing Prostate Tissue Compared to That in Benign Prostate Hyperplasia Tissue / 대한배뇨장애요실금학회지

In this article, a part of fund and grant supports was omitted unintentionally.

Increased Expression of Herpes Virus-Encoded hsv1-miR-H18 and hsv2-miR-H9-5p in Cancer-Containing Prostate Tissue Compared to That in Benign Prostate Hyperplasia Tissue / 대한배뇨장애요실금학회지

PURPOSE: Previously, we reported the presence of virus-encoded microRNAs (miRNAs) in the urine of prostate cancer (CaP) patients. In this study, we investigated the expression of two herpes virus-encoded miRNAs in prostate tissue. METHODS: A total of 175 tissue samples from noncancerous benign prostatic hyperplasia (BPH), 248 tissue samples from patients with CaP and BPH, and 50 samples from noncancerous surrounding tissues from these same patients were analyzed for the expression of two herpes virus-encoded miRNAs by real-time polymerase chain reaction (PCR) and immunocytochemistry using nanoparticles as molecular beacons. RESULTS: Real-time reverse transcription-PCR results revealed significantly higher expression of hsv1-miR-H18 and hsv2-miRH9- 5p in surrounding noncancerous and CaP tissues than that in BPH tissue (each comparison, P<0.001). Of note, these miRNA were expressed equivalently in the CaP tissues and surrounding noncancerous tissues. Moreover, immunocytochemistry clearly demonstrated a significant enrichment of both hsv1-miR-H18 and hsv2-miR-H9 beacon-labeled cells in CaP and surrounding noncancerous tissue compared to that in BPH tissue (each comparison, P<0.05 for hsv1-miR-H18 and hsv2- miR-H9). CONCLUSIONS: These results suggest that increased expression of hsv1-miR-H18 and hsv2-miR-H95p might be associated with tumorigenesis in the prostate. Further studies will be required to elucidate the role of these miRNAs with respect to CaP and herpes viral infections.

The TREK2 Channel Is Involved in the Proliferation of 253J Cell, a Human Bladder Carcinoma Cell

Bladder cancer is the seventh most common cancer in men that smoke, and the incidence of disease increases with age. The mechanism of occurrence has not yet been established. Potassium channels have been linked with cell proliferation. Some two-pore domain K+ channels (K2P), such as TASK3 and TREK1, have recently been shown to be overexpressed in cancer cells. Here we focused on the relationship between cell growth and the mechanosensitive K2P channel, TREK2, in the human bladder cancer cell line, 253J. We confirmed that TREK2 was expressed in bladder cancer cell lines by Western blot and quantitative real-time PCR. Using the patch-clamp technique, the mechanosensitive TREK2 channel was recorded in the presence of symmetrical 150 mM KCl solutions. In 253J cells, the TREK2 channel was activated by polyunsaturated fatty acids, intracellular acidosis at -60 mV and mechanical stretch at -40 mV or 40 mV. Furthermore, small interfering RNA (siRNA)-mediated TREK2 knockdown resulted in a slight depolarization from -19.9 mV+/-0.8 (n=116) to -8.5 mV+/-1.4 (n=74) and decreased proliferation of 253J cells, compared to negative control siRNA. 253J cells treated with TREK2 siRNA showed a significant increase in the expression of cell cycle boundary proteins p21 and p53 and also a remarkable decrease in protein expression of cyclins D1 and D3. Taken together, the TREK2 channel is present in bladder cancer cell lines and may, at least in part, contribute to cell cycle-dependent growth.

Quercetin-induced Growth Inhibition in Human Bladder Cancer Cells Is Associated with an Increase in Ca(2+)-activated K+ Channels

Quercetin (3,3',4',5,7-pentahydroxyflavone) is an attractive therapeutic flavonoid for cancer treatment because of its beneficial properties including apoptotic, antioxidant, and antiproliferative effects on cancer cells. However, the exact mechanism of action of quercetin on ion channel modulation is poorly understood in bladder cancer 253J cells. In this study, we demonstrated that large conductance Ca2+-activated K+ (BKCa) or MaxiK channels were functionally expressed in 253J cells, and quercetin increased BKCa current in a concentration dependent and reversible manner using a whole cell patch configuration. The half maximal activation concentration (IC50) of quercetin was 45.5+/-7.2 microM. The quercetin-evoked BKCa current was inhibited by tetraethylammonium (TEA; 5 mM) a non-specific BKCa blocker and iberiotoxin (IBX; 100 nM) a BKCa-specific blocker. Quercetin-induced membrane hyperpolarization was measured by fluorescence-activated cell sorting (FACS) with voltage sensitive dye, bis (1,3-dibutylbarbituric acid) trimethine oxonol (DiBAC4(3); 100 nM). Quercetin-evoked hyperpolarization was prevented by TEA. Quercetin produced an antiproliferative effect (30.3+/-13.5%) which was recovered to 53.3+/-10.5% and 72.9+/-3.7% by TEA and IBX, respectively. Taken together our results indicate that activation of BKCa channels may be considered an important target related to the action of quercetin on human bladder cancer cells.

Acquired Amegakaryocytic Thrombocytopenia after Thymectomy in a Case of Pure Red Cell Aplasia Associated with Thymoma / 대한진단검사의학회지

The association of thymoma with pure red cell aplasia has been well documented, but amegakaryocytic thrombocytopenia is not a recognized paraneoplastic syndrome complicating thymoma. We report a case of thymoma-complicated pure red cell aplasia and amegakaryocytic thrombocytopenia in a 73-yr-old woman. Pure red cell aplasia was diagnosed seven months after the detection of thymoma. One year after the diagnosis of pure red cell aplasia and seven months after thymectomy, bone marrow aspiration and biopsy showed an absence of megakaryocytes, marked erythroid hypoplasia with normal myeloid series. A diagnosis of amegakaryocytic thrombocytopenia and pure red cell aplasia was made. Oral steroid maintenance therapy resulted in recovery of platelet count. She has still transfusion-dependant anemia but platelet and neutrophil counts had been maintained in normal range for more than five months, until the last follow-up. We think that autoreactive T cells may induce a clinical autoimmune response even after eradication of thymoma, and aplastic anemia as a late complication following thymectomy was described in previous cases. This patient also has to be under a close observation because of the possibility to evolve into aplastic anemia.

Comparison of Blood Glucose Measurements Using Samples Obtained from the Forearm, Finger Skin Puncture, and Venous Serum / 대한진단검사의학회지

BACKGROUND: Blood glucose testing (BGT) at the forearm minimizes the pain experienced during sampling of capillary blood. We compared the BGT results for forearm sampling with those for standard finger skin puncture and venous serum to evaluate the clinical validity of forearm BGT. METHODS: BGT was performed on the finger (G(F)) and forearm (G(A)) with a portable glucometer in 555 subjects, including 61 diabetic patients, under fasting conditions. BGT with venous serum (G(V)) was followed within an hour in 514 subjects. Simple linear regression, intraclass correlation, and Passing-Bablok regression analyses were performed using the G(A)-G(F) and G(A)-G(V) data. RESULTS: G(A) showed an excellent linear relationship with both G(F) and G(V) with a Pearson correlation coefficient (r) of 0.97 (P<0.0001) in the patient group, which was similar to the findings in the normal group except for the lower r values. The mean bias between G(A) and G(F) and between G(A) and G(V) were within +/- 10 mg/dL in both groups. The intraclass correlation coefficients were slightly smaller than the corresponding r values, but they showed the same tendency in both groups. In the Passing-Bablok analyses, the 95% confidence intervals of the slope and intercept parameters were <+/-20% of unity and <+/-20 mg/dL, respectively, which were within the acceptable ranges. All 3 statistical analyses supported the satisfactory agreement of G(A) with G(F) or G(V). CONCLUSIONS: BGT at the forearm was highly consistent with the standard BGT, thereby confirming its applicability in clinical practice for self-testing under steady fasting conditions.

A Belt-type Biomedical Mobile Device / 대한의료정보학회지

OBJECTIVE: To investigate a belt-type, biomedical mobile device capable of measuring patients' biomedical signals and sending the biomedical data to a remote medical server. This device was designed to measure and record ECG and motion signals continuously for a moving subject and, on in the event of an emergent situation, to notify a remote doctor of the situation by transmitting data on the emergent situation to a remote server through a CDMA network. METHODS: The developed system is composed of three parts: biomedical signal acquisition, biomedical data recording, and data transmission. We conducted four types of experiment in order to evaluate the developed system's accuracy, reliability, operability, applicability to daily life, and SMS alarm function. First, we tested the accuracy of the R-R interval by comparing the signals measured via the developed system with those via a commercialized ECG system while the subjects were sitting, standing, lying or cycling. Second, we tested the reliability of the transmitted data to the remote server when two types of emergent events are generated in the developed system using a patient simulator, and measured the battery life to determine the system life. Third, we experimentally examined the accuracy of the corresponding data transmitted to the remote server via the CDMA network when two types of event are generated for each of seven types of action (sitting, standing, standing up from the seat, ordinary walking, fast walking, cycling, and running) during daily life. Lastly, we tested the SMS alarm function. RESULTS: The acquisition and comparison of the subjects' biomedical signals and motion signals confirmed the accuracy, reliability, operability and applicability of the developed system to daily life. The ability of the system to monitor the ECG signals and motion signals during daily life was also demonstrated. CONCLUSION: The system was demonstrated to be very applicable to subjects requiring continuous monitoring for chronic disease and health management. Therefore, the developed system is expected to play an important role in building ubiquitous healthcare systems in Korea in the near future.

Diversity of Ion Channels in Human Bone Marrow Mesenchymal Stem Cells from Amyotrophic Lateral Sclerosis Patients

Human bone marrow mesenchymal stem cells (hBM-MSCs) represent a potentially valuable cell type for clinical therapeutic applications. The present study was designed to evaluate the effect of long-term culturing (up to 10th passages) of hBM-MSCs from eight individual amyotrophic lateral sclerosis (ALS) patients, focusing on functional ion channels. All hBM-MSCs contain several MSCs markers with no significant differences, whereas the distribution of functional ion channels was shown to be different between cells. Four types of K+ currents, including noise-like Ca+2-activated K+ current (IKCa), a transient outward K+ current (Ito), a delayed rectifier K+ current (IKDR), and an inward-rectifier K+ current (Kir) were heterogeneously present in these cells, and a TTX-sensitive Na+ current (INa,TTX) was also recorded. In the RT-PCR analysis, Kv1.1, heag1, Kv4.2, Kir2.1, MaxiK, and hNE-Na were detected. In particular, INa,TTX showed a significant passage-dependent increase. This is the first report showing that functional ion channel profiling depend on the cellular passage of hBM-MSCs

A PDA-Based Wireless ECG Monitoring System for u-Healthcare / 대한의료정보학회지

OBJECTIVE: The purpose of this study is to design a portable ECG monitoring system, which integrates up-to-date PDA and RF communication technology, and to acquire the subject's biomedical signal without any constraint. METHODS: The developed system is composed of a transmitter and a receiver. The transmitter has a MCU (microcontroller), three-axial acceleration sensor, ECG amplifier and Zigbee communication controller. It has two types of transmission mode, which are total signal transmission mode and HR (heart rate)/SC (step count) transmission mode. The receiver has a MCU, Serial Communication IC, and Zigbee communication controller. It forwards the received data to PDA, where the data can be stored and displayed. RESULTS: In total signal transmission mode, it can send data 60 packets per second whose transmission speed corresponds to 300 ECG samples and 60 acceleration samples. In HR/SC transmission mode, it can calculate heart rate from ECG data with 216 samples per second and step count from acceleration data and send a packet every cardiac cycle. CONCLUSION: Using this device, a new method of remote monitoring both vital sign and activity is realized. A PDA-based wireless ECG system enables patients to be monitored during their daily living, without any constraints. Also, this method will reduce medical costs in the aged society.

Development of a PDA based Personal Asthma Management System / 대한의료정보학회지

OBJECTIVE: The purpose of this study was to self-management asthma including symptom, medication, and to prevent the exacerbation of the condition using the Personal Asthma Management System(PAMS) which was developed based on Personal digital Assistant(PDA). METHODS: A development tool of the PAMS was EVC(Microsoft Embadded Visual C++). The system contents referred to workshop report of the Global Initiative for Asthma, on-line lecture of the Korean Society of allergology and Korea Asthma allergy Foundation, asthma-related web-sites. RESULTS: The PAMS was implemented with four main menus: personal information, symptom, medication management, and self care. The patients input their daily condition, and this data will be used in the successful prevention and management of asthma exacerbation. This real-time nature of PAMS is its primary advantage over other retrospective computing system for reducing the effects of forgetting, so this information will be useful in classifying of asthma severity. CONCLUSION: The PAMS can be contributed to aid self-management of asthma and effective treatment by attending physician.

PDA Based Point-of-care Personal Diabetes Management System / 대한의료정보학회지

OBJECTIVE: To develop a PDA based hand-held system, which assists diabetic patients to self manage his/her blood glucose level, diet, and other related variables in a systematic way. METHODS: Personal diabetes management system(PDMS) was developed in the integrated environment of Visual Studio.net 2003. The system was configured based on the documentation resulted from extensive review on the current S/W products and internet homepages for the diabetes. RESULTS: PDMS was implemented with four main menus to manage personal information, diet, exercise, and blood glucose. It was designed to provide the quantitative health indices such as body mass index and diabetes index based on the personal physical information, pedigree, and living habits. It addition, it is capable of predicting changes of the body weight, which may remind patients of the importance of the disease management. CONCLUSION: A PDA based hand-held self management system was developed for the diabetes. The present system can be used as a mobile device within the tele-healthcare system integrated with medical center thru the internet.

Development Brief of Embedded Computing Technology for Mobile Wi reless Biotelemetry / 대한의료정보학회지

Embedded computing and wireless communication technology were used to develop a mobile biotelemetry system, featuring the functions of mobile measurement, wireless transmission, database archival, and internet retrieval of biomedical signals. Two PPCs (Pocket PC) with WLAN (wireless LAN) PC cards were used to simulate the communicating situation of biomedical signals between wireless sensors and a personal monitor. A PPC client program simulated the wireless sensors and a PPC server program simulated the personal medical monitor. Medical PDA was implemented by SBC (single board computer), LCD display, touch screen and Bluetooth module. Windows CE.net was ported as its operating system and the application program was developed using embedded Visual C++ 4. The measured transmission speed of ECG data was 2150 samples per second in the WLAN environment. For wireless internet connection, a Web-based server program was developed, able to display the biomedical signals of remote patients and be remotely monitored by medical doctors in a distant hospital. PDA data, which was archived at the server's database table, was transformed to an XML message and could be displayed on a Web browser as a signal graph. This system would be very useful for patients with chronic illness, especially in an emergent environment, and for containing medical cost in the aged society.

Error Compensation Technique for Peak Expiratory Flow Meter Operated by Spring Force / 대한의료정보학회지

Peak expiratory flow meter(PEFM) is a portable medial device used for home health care of chronic respiratory diseases such as asthma. PEFM adapts spring principle for convenient measurement of expiratory peak flow rate, however linear scale could lead to a substantial measurement e rror. The pre sent study identified inherent er ror of the device by theore tical ana lysis, and accurately measured the error of a patented commercial PEFM. Consistent error was observed mainly due to non-linearity of the flow-to-distance conversion principle, which could be fitted to a quadratic formula with satisfactory accuracy. A simple error compensation technique was accordingly proposed based on quadratic error modeling, which decreased measurement error down to less than 1/3 of before- compensation corresponding to only an error of less than 15LPM over a wide range of flow(100-500LPM). Error compensation table was constructed for convenient use of patients. The present error compensation technique is simple and convenient not only to enhance home health care quality but also for the manufacturers to build more accurate PEFM devices.

Identification of Epidural Space with a Pressure Detection Apparatus / 대한마취과학회지

BACKGROUND: Techniques for identification of the epidural space have advantages and disadvantages. We made an electronic apparatus to ensure an epidural space by detecting the reduction of pressure. We investgated the instrument to see if this could be adequately used for identification of the epidural space. METHODS: Thirty adult patients scheduled to receive an epidural injection for surgery were selected for the investigation. We connected the apparatus with an epidural Tuohy needle of which the tip was in the ligamentum flavum. We injected air to increase the pressure inside the epidural needle to 50 mmHg or 100 mmHg, and then the epidural needle was advanced slowly until we heard the alarm from the epidural detector when pressure inside the epidural needle suddenly decreased under the set point, suggesting the epidural needle reached the epidural space. After ensuring the epidural space we injected the anesthetics to induce epidural anesthesia. RESULTS: In both groups, we obtained successful anesthesia results and there were no complications. The volume of air injected into the epidural space was 0.64 +/- 0.1 in 50 mmHg group and 0.95 +/- 0.2 in 100 mmHg group. CONCLUSIONS: The use of the epidural detector in 30 patients demonstrated that this instrument could be a safe and effective means of identifying the epidural space. It allows the reduction of air injected into the epidural space, reducing the chance of complications due to an overinjection of air.

The Interactive Virtual Endoscope for Navigation of Anatomy Model / 대한의료정보학회지

A optical endoscope has disadvantages; giving pain and not applying to a postoperative patient. If it substitutes for a virtual endoscope, noninvasive observation can be gained. This paper describes a developed viewer, using Visual C++ 6.0 and Openlnventor2.5.2 (object-oriented 3D toolkit) library, for the manipulation of 3D anatomy object model. It is named Anatomy Viewer. The viewer is implemented under the PC environment. It can rotate, zoom in and out, and fly through anatomy models on 3D space and translate into a interested area, and then save as a TGA image file like a real endoscope. Also, as it is improved in the network, we exchange data and discuss with someone who is in the other place. This viewer is very useful to understand the anatomy structure, to diagnose, and to make a surgical plan in preoperative step. We verified its usefulness by observing a 3D bronchus model that is reconstructed with CT image slices.

Effects of Low-dose Androgen in Combination with Subcutaneous Recombinant Human Erythropoietin (r-HuEPO) on Anemia and Nutritional Parameters in Hemodialysis Patients / 대한신장학회잡지

Recombinant human erythropoietin(r-HuEPO) is the mainstay of anemia therapy in patient with end stage renal disease(ESRD), but the use of r-HuEPO is primarily limited by its high cost. So, it encourages any strategies that potentially enhance the erythropoietic response. However, studies designed to assess whether androgens would enhance the response to r-HuEPO were inconclusive. While androgens may be less expensive and may improve several nutritional parameters, their potential adverse effects discourage usage. We carried out a prospective study to examine the effect of low-dose androgen in combination with subcutaneous r-HuEPO on anemia and nutritional paramenters in hemodialysis patients. Twenty-four hemodialysis patients with hematocrit <24% or hemoglobin <8.0g/dL were randomly assigned into two groups. Group A(n=12) received 2000U r-HuEPO subcutaneously twice a week for six months. Group B(n=12) received the same dose of r-HuEPO plus nandrolone decanoate 100mg intramuscularly biweekly. Anthropometry, albumin, cholesterol, prealbumin, and transferrin were measured as nutritional parameters. The groups showed no differences in baseline levels of the followings : Hemoglobin, hematocrit; transferrin saturation; serum ferritin; intact serum parathyroid hormon, Kt/V; vitamin B12, folate; nutritional parameters. At the completion of the study, both groups showed significant increase in hematocrit compared with baseline levels(group A 20.7+/-2.2% to 26.0+/-3.8%; group B : 21.5+/-3.5% to 30.1+/-2.8%). The mean hematocrit in group B was significantly higher than in group A after 4 month study period(p<0.05). Ten of 12 patients in group B achieved a target hematocrit of 30%, as compared with four of 12 patients in group A. Both groups didn't show significant changes in any nutritional parameters. No significant side effects of androgen were noted during this short-term study. We conclude that low-dose androgen in combination with subcutaneous r-HuEPO is effetive treatment on anemia in hemodialysis patients, but does not improve nutritional status.

Error Minimization of Respiratory Air Flow Measurement by Pneumotachometer / 대한의료정보학회지

Pneumotachometer is the most widely used respiratory air flow sensor. But the measurement error hard to be ignored exists, since the empirical calibration carve in a closed form cannot provide accurate flow values at all measured pressure data. Any possible distortion of the calibration curve further increases measurement error, which cannot he corrected by the conventional calibration method. The present study suggests a new error correction algorithm applicable to any type of pneumotachometer equipped with computer-based data processing device. This algorithm evaluates conductance error correction coefficients at each digitized pressure level based on the cumulative pressure data obtained by manual volume syrange stroke operation at different speeds. Experiment demonstrated error minimization down to below 1/10 in mean stroke volume measurement compared to the conventional calibration curve method. The standard deviation of the stroke volume also decreased down to below 1/2 of the conventional method. The present technique can be introduced with no difficulty to the calibration procedure the American Thoracic Society, and expected to guarantee the accuracy and reliability of the respiratory air flow measurement during spirometric tests.

Validation of the Histogram Summation Technique for Measurement Error Minimization of Respiratory Air Flow Rate / 대한의료정보학회지

The present study performed an experiment to validate the histogram summation technique developed for measurement error minimization of respiratory air flow rate2). Five sets of manual stroke operation data(MSO#1 5) of 1 [LI each were acquired at varying speeds. Selected sets of these data were used to estimate the conductance correction factors reflecting the resistance-flow character -istics. Then the correction factors were applied to different sets of the data to evaluate mean SD of the volume measurement error. When the resistance was linearly compensated without conductance correction, the relative error was 2.3% marginally within the ATS standard limit of 3%. With the histogram summation techinque applied, it has dramatically decreased down to within 1%. For a newly input flow data, the error was maintained within 1.5%. Therefore, the histogram summation techinque minimized the measurement error consistently and reproducibly. With increased number of strokes included in the correction factor estimation process, the error decreased at a rate of 0.5 [mL!S0strokesj. However, no more than 50 stroke data were necessary to keep the measurement error within 1.5%. This corresponded to only 25 MSO, thus the histogram summation technique has been demonstrated to be consistent, reproducible, and practical technique for measurement error minimization of respiratory air flow rate.