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At least 1,603 records · Page 89Linked to original sources
PubMed1998

[Time-varying spectral analysis of cardiac murmurs].

In this paper, the cardiac murmurs (systolic murmurs, diastolic murmurs and machining murmurs) are classified by hemodynamics and studied by time-frequency analysis. We get the time-varying spectrum of the signals. The results, which are from the different kinds of murmurs in 28 patients with heart disease, show that the time-varying spectrum based on cone-shaped kernel distribution are capable to correctly represent the power density and dynamic course of the series in time-frequency domain. The method has high time-frequency resolution, and the time-varying spectrum of each murmur has its characteristics.

Electrophysiology↗
PubMedDate not supplied

Power spectral analysis of heart rate variability in children with aortic stenosis.

Aortic stenosis is a progressive disorder and can be the cause of serious arrhythmias and possibly sudden death. Evaluation and follow-up of the autonomic nervous system may provide some useful information for management of the disease. Our study aimed to examine heart rate variability in children with aortic stenosis in the supine position and to detect the changes in autonomic activity during head-up tilt testing. Sixteen patients and 11 healthy controls participated in the study. In the supine position, seven minutes of continuous echocardiographic (ECG) recording was performed, followed by four consecutive ECG recordings, each consisting of seven minutes in 70 degrees tilt position. To obtain power spectrums, the tachograms were taken on the autoregressive mode. The mean RR interval duration, standard deviation of RR interval, central frequencies of low and high frequency oscillations, their powers, total power and percents of normalized low and high frequency powers were accepted for statistics. There were no significant differences between the groups in the supine position. In tilt position, mean RR interval and its standard deviation were decreased in both groups. The central frequency of low freuquency power significantly (p<0.05) shifted to left, normalized low frequency power increased and normalized high frequency power decreased in the control group at the beginning of tilt position, but at the second phase of tilt position in the patient group. We conclude from the results that children with mild-to-moderate aortic stenosis reflect delayed response to sympathetic provocation.

Adolescent↗
PubMed2001

[Deep breathing test type I diabetic patients and parameters of spectral analysis].

UNLABELLED: Nervous system injury, affecting also its autonomic part, occurs in the natural course of chronic complications in patients with type 1 and 2 diabetes. The aim of the study was to compare heart rate frequency analysis parameters at rest and after deep breathing test in healthy persons and in the group of type 1 diabetes patients without complications. The study was performed in 34 patients with type 1 diabetes without chronic complications (N0), hospitalized in the Chair and Department of Metabolic Diseases in 1993-1996. The control group (K) consisted of 23 healthy persons. All diabetic patients underwent examinations to identify chronic complications of the disease. Aiming at answering the question how simple physiological tests influence frequency parameters of heart rate variability, assessment of VLF, LF and HF parameters was performed at rest and after the deep breathing test. In both groups K and N0 no changes were observed in the spectrum power within VLF values after deep breathing compared to the initial values. In the group K the deep breathing test significantly (p < 0.001) increased spectrum power within LF values, whereas in the group N0 the test did not produce statistically significant changes of this parameter compared to the initial values. In the control group K as well as in diabetic patients N0 the test caused significant (p < 0.01 and p < 0.001, respectively) decrease in the HF spectrum power in comparison to the values at rest. VLF/LF ratio after the deep breathing test as well as LF/HF ratio at rest were significantly lower in the group K compared to the group N0. CONCLUSION: Analysis of the autonomic nervous system imbalance may be an indispensable tool in the early diagnostics of patients with type 1 diabetes. Results of spectrum analysis may be useful in cases when classical Ewing battery tests do not identify autonomic dysfunction.

Adult↗
PubMed2002

Mass spectral analysis of PC-SPES confirms the presence of diethylstilbestrol.

INTRODUCTION/OBJECTIVES: PC-SPES is an herbal mixture available over the counter for the treatment of prostate cancer. It was re-called in January 2002 due to alleged contamination with warfarin. Other laboratories, including our own, claim that the potent synthetic estrogen, diethylstilbestrol (DES) which has been used for many years to treat hormone dependent prostate cancer, could be detected in the herbal mixture. Recent clinical studies report objective responses in men with hormone dependent and naïve prostate cancer, and also describe isolated cases of estrogenic side effects. A lack of effective conventional treatments for advanced hormone refractory prostate cancer has led to a widespread use of PC-SPES by patients across the North America continent. The presence of DES in PC-SPES might explain both clinical response and observed side effects in men taking 6-9 capsules per day. METHODS: We tested five batches of commercially available PC-SPES using gas chromatography (GC) and high performance liquid chromatography (HPLC) upon methanolic extraction. Duplicate aliquots were tested for each batch and the results compared to standard curves generated using DES (99% purity). RESULTS AND CONCLUSIONS: We detected significant levels of DES in three out of five tested batches. The presence of a synthetic steroid in PC-SPES is not likely to have occurred as a result of its extraction from a herbal source. The implications of this finding highlight the necessity of regulated quality control and standardization of natural health products.

Chromatography, Gas↗
PubMed2000

[Information technology of modern NIR spectral analysis].

The main points, flowdiagram and the levels of optimization and building models of modern NIRS analysis are described in this paper. The strategy of how to apply and develop the technology of Near-Infrared spectroscopy analysis in our country is also described. In order to develop the technology of NIRS, the Industrialization and Democratization should combined.

Electronic Data Processing↗
PubMed2003

[Spectral analysis of the structure of 1, 1'-and 1, 2'-dinaphthyl methanone].

The structure of 1, 1'-and 1, 2'-dinaphthyl methanone synthesized by the reaction of naphthalene with oxalyl chloride in the presence of AlCl3 were studied by using UV and FTIR in this paper. The analysis results showed that the difference of structures (symmetry) of 1,1'-and 1, 2'-dinaphthyl methanone were represented on the obvious difference of the spectra of UV and FTIR.

Molecular Structure↗
PubMed2002

[Application of AOTF in spectral analysis. 2. Application of self-constructed visible AOTF spectrophotometer].

The performances of a self-constructed visible AOTF spectrophotometer are presented. The wavelength calibration of AOTF1 and AOTF2 are performed with a didymium glass using a fourth-order polynomial curve fitting method. The absolute error of the peak position is usually less than 0.7 nm. Compared with the commercial UV1100 spectrophotometer, the scanning speed of the AOTF spectrophotometer is much more faster, but the resolution depends on the quality of AOTF. The absorption spectra and the calibration curves of copper sulfate and alizarin red obtained with AOTF1(Institute for Silicate, Shanghai China) and AOTF2 (Brimrose U.S.A) respectively are presented. Their corresponding correlation coefficients of the calibration curves are 0.9991 and 0.9990 respectively. Preliminary results show that the self-constructed AOTF spectrophotometer is feasible.

Acoustics↗
PubMed2001

[Study on the direct interaction between alkaline phophatase and Cu(II) ions by spectral analysis].

In this paper, the results of EPR, VIS and enzyme activity show that alkaline phophatase from calf intrest directly interacted with additional Cu(II). The added Cu(II) enter into A site of active sites of AKP which decrease enzyme activity. With increase of pH value, the decrease in the intensity of the Cu(II) EPR signal and the change of place signal in VIS were observed. These results suggest that Cu(II) migrate in the active center of the enzyme.

Alkaline Phosphatase↗
PubMed2001

[Spectral analysis on self-assembly ultrathin film of polyaminobenzonitrile].

Poly(p-amino benzonitrile) (PABN) was synthesized by the method of plasma polymerization. With the self-assembly techniques, an ultrathin film of PABN and NaPSS (sodium polystyrene sulfonate) was successfully prepared. UV-Visible absorption spectra revealed that the film is very regular. This is a new method to prepare ultrathin film of PABN.

Macromolecular Substances↗
PubMed2001

[Application of digestion pot of HP hermetic seal in sample pretreatment in spectral analysis].

Atomic absorption spectrometry is a rapid and effective method for the quantitative determination of elements, but in complete dissolution of solid sample can greatly influence the analytical accuracy. The scale sample obtained from the power plant is hardly to digestion. In this paper, a method is proposed namely digestion pot of HP hermetic seal, it can digest the scale sample, and the digestion condition is obtained. After the sample is completely digested, the conventional elements in scale sample is determined by atomic absorption spectrometry.

Copper↗
PubMed2000

[The preparation of electric arc method and spectral analysis on long persistence luminescent chinaware of SrAl2O4:Eu2+].

Luminescent chinaware of long persistence of SrAl2O4:Eu2+ has been prepared with using are method. Fluorescence and excitation spectra were measured in order to study its luminescence and long persistence properties. Results show that both of luminescent chinaware and polycrystalline powdered phosphor are the same in luminescence decay and consist of an initial fast process and a later extremely slow process. Long persistence properties of luminescent chinaware are better more than polycrystalline powdered phosphor, and its function of environment-resistant has been improved prominently.

English Abstract↗
PubMed2000

[Study on the interaction of copper-zinc superoxide dismutase with cobalt(II)-tryptophane by spectral analysis].

The effect of changing the amount of external added Co(trp)n and pH values on the interaction of Cu2Zn2 SOD with organic metal compound (Cobalt(II)-Tryptophane) have been studied by means of ICP, VIS and measurement of enzyme activity. It has found that in aqueous solution, there exists a direct interaction of the metal ions of the active center in the metalloenzyme (Cu2Zn2 SOD) with external added Co(Trp)n. As a result, part of the metal ions in metalloenzyme were replaced and the corresponding metalloenzyme derivatives (Co(II)-substituted derivatives of SOD) were produced and the catalytic activity of enzyme were affected. It has also studied the intensity of interactions in different molar ratios (Cobalt(II)-Tryptophane) and pH values and got some results under the effect of corresponding factors.

Cobalt↗