Biomedical Parameters Research Articles

Bioanalytical flow-injection system for control of hemodialysis adequacy

Potentiometric urea biosensor based on ammonium-ion selective electrode has been used in simple flow-injection bioanalytical system for the determination of removed urea in effluent liquid during hemodialysis treatment. The interferences from other components of the spent dialysate (mainly potassium ions) were eliminated using reference cell detector with non-sensitized ammonium-ion electrode. The methods of signal correction were discussed. The presented flow injection analysis (FIA) system allowing monitoring of urea content in the range of concentrations correspond well with the amount of the analyte in real samples (1–20mmol/l). Around 25 samples per hour can be analyzed. Due to long operational life-time of the applied biosensor the FIA system can be useful over 3 weeks. The presented biosensor/FIA system has been successfully applied for the biomedical control of real clinical processes. The results of analysis are useful for the evaluation of the clinical parameters of urea kinetic modeling: parameters KT/V, urea reduction ratio (URR), percentage removal of urea (PRU) and total urea removal (TUR) for intradialytic intervals and urea generation rate (G) and protein catabolic rate (PCRn) for interdialytic intervals. These biomedical parameters are used for describing the adequacy of hemodialysis therapy.

GLLS for optimally sampled continuous dynamic system modeling: theory and algorithm

The original generalized linear least squares (GLLS) algorithm was developed for non-uniformly sampled biomedical system parameter estimation using finely sampled instantaneous measurements (D. Feng, S.C. Huang, Z. Wang, D. Ho, An unbiased parametric imaging algorithm for non-uniformly sampled biomedical system parameter estimation, IEEE Trans. Med. Imag. 15 (1996) 512–518). This algorithm is particularly useful for image-wide generation of parametric images with positron emission tomography (PET), as it is computationally efficient and statistically reliable (D. Feng, D. Ho, Chen, K., L.C. Wu, J.K. Wang, R.S. Liu, S.H. Yeh, An evaluation of the algorithms for determining local cerebral metabolic rates of glucose using positron emission tomography dynamic data, IEEE Trans. Med. Imag. 14 (1995) 697–710). However, when dynamic PET image data are sampled according to the optimal image sampling schedule (OISS) to reduce memory and storage space (X. Li, D. Feng, K. Chen, Optimal image sampling schedule: A new effective way to reduce dynamic image storage space and functional image processing time, IEEE Trans. Med. Imag. 15 (1996) 710–718), only a few temporal image frames are recorded (e.g. only four images are recorded for the four parameter fluoro-deoxy-glucose (FDG) model). These image frames are recorded in terms of accumulated radio-activity counts and as a result, the direct application of GLLS is not reliable as instantaneous measurement samples can no longer be approximated by averaging of accumulated measurements over the sampling intervals. In this paper, we extend GLLS to OISS-GLLS which deals with the fewer accumulated measurement samples obtained from OISS dynamic systems. The theory and algorithm of this new technique are formulated and studied extensively. To investigate statistical reliability and computational efficiency of OISS-GLLS, a simulation study using dynamic PET data was performed. OISS-GLLS using 4-measurement samples was compared to the non-linear least squares (NLS) method using 22-measurement samples, GLLS using 22-measurement samples and OISS-NLS using 4-measurement samples. Results demonstrated that OISS-GLLS was able to achieve parameter estimates of equivalent accuracy and reliability in comparison to NLS or GLLS using finely sampled measurements (22-measurement samples), or OISS-NLS using optimally sampled measurements (4-measurement samples). Furthermore, as fewer measurement samples are used in OISS-GLLS, this algorithm is computationally faster than NLS or GLLS. Therefore, OISS-GLLS is well-suited for image-wide parameter estimation when PET image data are recorded according to the optimal image sampling schedule.

Generalized linear least squares algorithm for non-uniformly sampled biomedical system identification with possible repeated eigenvalues

The recently developed generalized linear least squares (GLLS) algorithm has been found very useful in non-uniformly sampled biomedical signal processing and parameter estimation. However, the current version of the algorithm cannot deal with signals and systems containing repeated eigenvalues. In this paper, we extend the algorithm, so that it can be used for non-uniformly sampled signals and systems with/without repeated eigenvalues. The related theory and detailed derivation of the algorithm are given. A case study is presented, which demonstrates that the extended algorithm can provide more choices for system identification and is able to select the most suitable model for the system from the non-uniformly sampled noisy signal.

Serum Mn-superoxide dismutase in acute myocardial infarction.

The acute myocardial infarction (AMI) model was established through rabbits, and this kind of model was used to investigate the possible mechanism for the AMI mediated damage, induced by NO release and oxidative stress. The biomedical parameters nitric oxide (NO), total antioxidant capacity (TAC) variation in vivo and the enzymatic activity of nitric oxide synthase (NOS) and superoxide dismutase (SOD), which are considered as the major markers for pathophysiological variation, were detected. The results obtained gave evidence that AMI can lead to the NO excess release and compensation by excess cellular respiration, and both of them can result in oxidative stress and further generation of reactive oxygen species (ROS). The latter can bring a series of damages to the organism, including decrease of the TAC value, and NOS and SOD activity.

人間ドック受診者におけるLp(a)の検討

人間ドック受診者におけるLp(a)の検討

An Efficient Estimation Method for Biomedical System Modeling

A generalized linear least squares (GLLS) algorithm for non-uniformly sampled biomedical system parameter estimation is proposed. This algorithm is generally applicable to a variety of models with different structures and can produce unbiased parameter estimation. As this algorithm requires very little computing time, it can potentially be used for generating parametric images.

Environment and biomedicine: A prospective research

Environmental evolution induces biological evolution. Man is more and more rapidly and deeply transforming his ecosystem with his exponential technical advances. This generally results in overall progress for health, as is shown by the increase in man's life span, but he also introduces new risks into his environment, and these are often only detected at long term. Continuous computation of the relationships between both environmental and biomedical parameters, which are increasingly well discriminated and quantified as a result of scientific (geophysical, spatial, molecular and genetic) research advances, should enable prospective survey not only of the effects of the introduction in human ecosystems of new physical energies, new chemicals, but also of the development of new viral diseases. The dimensions of the world biosphere are continuously shrinking as a measure of enhanced communication facilities and our planet's increasing population. A prospective approach to the environmental biomedical risks, or benefits should therefore be considered a worldwide enterprise.

Preservation of the porcine pancreas with HTK and Euro‐Collins solution: studies in a reperfusion system

The present study compares the preservation of the porcine pancreas by the standard Euro-Collins solution or the cardioplegic histidine-tryptophan-ketoglutarate solution (HTK). The explanted pancreas was stored at 4 degrees C for 6 and 24 h respectively, following which organ quality was assessed in a reperfusion chamber measuring physiological and biomedical parameters. After 6 h ischaemia, the amount of lactate was significantly lower when HTK was used for protection. Other parameters like insulin release, amylase release, vascular resistance and oxygen consumption of the pancreas did not indicate a significant difference. Protection with HTK significantly improved pancreas preservation after 24 h ischaemia: lactate content in the reperfusate was lower (HTK: 64.0 +/- 7.2 mumol 50 ml-1 n = 8, v. EC: 114.2 +/- 1.7 mumol 50 ml-1, n = 6), the arteriovenous flow rate was higher (HTK: 5.7 +/- 0.91 ml min-1 v. EC: 3.0 +/- 0.26 ml min-1), and the pancreatic oxygen consumption was increased (HTK: 2.15 +/- 0.22 microliter O2 min-1 g-1 v. 0.47 +/- 0.08 microliter O2 min-1 g-1). We conclude that pancreas preservation can be improved in vitro by protection with HTK solution.

Preservation of the porcine pancreas with HTK and Euro‐Collins solution: studies in a reperfusion system

Abstract. The present study compares the preservation of the porcine pancreas by the standard Euro‐Collins solution or the cardioplegic histidine‐trypto‐phan‐ketoglutarate solution (HTK). The explanted pancreas was stored at 4°C for 6 and 24 h respectively, following which organ quality was assessed in a reperfusion chamber measuring physiological and biomedical parameters. After 6 h ischaemia, the amount of lactate was significantly lower when HTK was used for protection. Other parameters like insulin release, amylase release, vascular resistance and oxygen consumption of the pancreas did not indicate a significant difference. Protection with HTK significantly improved pancreas preservation after 24 h ischaemia: lactate content in the reperfusate was lower (HTK: 64.0±7.2μmol 50 ml‐1 n= 8, v. EC: 114.2pM1–7 μmol 50 ml‐1, n= 6), the arteriovenous flow rate was higher (HTK: 5.7pM0.91 ml min‐1 v. EC: 3.0pM0.26 ml min‐1), and the pancreatic oxygen consumption was increased (HTK: 2.15pM0.22 μl O2 min‐1 g‐1 v. 0.47pM0.08 μl O2 min‐1 g‐1). We conclude that pancreas preservation can be improved in vitro by protection with HTK solution.

第16回日本総合健診医学会学術大会講演抄録 LPC式生活習慣検査による生活習慣尺度と生物医学的諸検査値との関連について―冠動脈性心疾患 (CHD) の危険因子を中心にして―

第16回日本総合健診医学会学術大会講演抄録 LPC式生活習慣検査による生活習慣尺度と生物医学的諸検査値との関連について―冠動脈性心疾患 (CHD) の危険因子を中心にして―

Theory and development of fluorescence-based optochemical oxygen sensors: oxygen optodes.

As the preceding considerations concerning the physical and technical features of oxygen optodes have demonstrated, fluorescence-based optochemical oxygen sensors possess certain advantages and peculiarities compared to conventionally applied electrochemical sensors such as polarographic oxygen electrodes. First, in contrast to oxygen electrodes, oxygen measurements with oxygen optodes do not suffer from distortions caused by the reference electrodes. In addition, because of the polarographic process, platinum electrodes continuously consume oxygen, which falsifies the results, especially when small sample volumes or long-term measurements, or both, are involved, whereas the sensor layer of oxygen optodes must only be equilibrated. Moreover, the surface of the platinum wire has to be catalytically clean in order to obtain a plateau of the polarogram and, consequently, to achieve a low rest current at zero PO2. Unfortunately, the demand for catalytically clean platinum surfaces turns out to be rather critical, since surface contamination occurs even with membranized electrodes, resulting in the well-known phenomenon of "electrode poisoning." The question of the specificity of oxygen electrodes also must be considered. In this context, CO2 and halothane may interfere with oxygen measurements, whereas fluorescence quenching is unaffected by CO2 and halothane affects the measurements only slightly, depending on the special indicator used. Furthermore, because of the flow dependence, oxygen measurements with the oxygen electrode show a distinct "stirring effect" caused by the turbulence in front of the electrode, which disturbs the diffusion field. Because of the completely different physical principle of fluorescence optical sensors, such influences are not observed with oxygen optodes. In addition, isolation and shielding of electrical circuits found in electrodes are not necessary for optodes. Furthermore, the sensitivity of oxygen optodes can be tuned to the desired range of PO2 values, resulting in a higher resolution. Use of suitable polymer alloys as indicator matrices can even enhance oxygen sensitivity; therefore, the application of optodes for trace analysis of oxygen might be possible, especially with regard to the application of highly oxygen-sensitive phosphorescent indicators. Finally, owing to the reversibility of fluorescence quenching, monitoring of oxygen by fluorescence optical sensors allows a continuous and remote control of biomedical parameters as well as regulation of biotechnological processes.(ABSTRACT TRUNCATED AT 400 WORDS)

Melting point of gallium as a temperature calibration standard

Enzyme reaction rates and other biomedical parameters depend critically upon temperature, and require accurate temperature measurement. A variety of thermometers are available, but these require reference to and calibration against a standard. The melting temperatures of pure metals are constants of nature, and during phase transition provide stable temperature environments for thermometer calibration. Pure gallium melts at 29.770 °C (IPTS68) and is shown to be a suitable standard for the calibration of thermometers in the biomedical range.