Biomedical subjects

Y P Zheng

Publications and source records attributed to Y P Zheng.

At least 19 recordsLinked to original sources

PubMed2006

Assessment of muscle fatigue using sonomyography: muscle thickness change detected from ultrasound images.

Muscle fatigue is an exercise-induced reduction in maximal voluntary muscle force. As the surface electromyography (SEMG) can be used to estimate the features of neuromuscular activations associated with muscle contractions, it has been widely employed as an objective tool to evaluate muscle fatigue. On the other hand, ultrasound imaging can inherently provide the morphological information of individual muscle, thus the architectural changes of muscles during fatigue can be obtained. In this study, we demonstrated the feasibility of using the dimensional change of muscles detected by ultrasound images, named as sonomyography (SMG), to characterize the behavior of muscles when they were in fatigue. The SEMG signals of the muscles were also recorded simultaneously and used for comparison. The right biceps brachii muscles of 8 normal young male adult subjects were tested for 30s under 80% of the maximal voluntary isometric contraction. The muscle fatigue was indicated by the change of the root-mean-square (RMS) and median frequency (MDF) of the SEMG signals. The results showed that the SEMG RMS had a linear increase with time with a rate of 2.9+/-1.9%/s (mean+/-S.D.), while the MDF decreased linearly with a rate of -0.60+/-0.26Hz/s. The muscle thickness, detected from the ultrasound images, continuously increased during the muscle fatigue but with a nonlinear increase with time, which was rapid during the initial 8.1+/-2.1s with a mean deformation rate of 0.30+/-0.19%/s and then became slower with a rate of 0.067+/-0.024%/s up to 20s after the contraction. The muscle deformation at 20s was 3.5+/-1.6%. The results demonstrated that the architectural change of muscles detected using SMG could potentially provide complementary information for SEMG for the muscle fatigue assessment.

Adult↗

PubMed2006

Ultrasound palpation sensor for tissue thickness and elasticity measurement--assessment of transverse carpal ligament.

Palpation is a traditional diagnostic procedure for health care professionals to use their fingers to touch and feel the body soft tissues. It is a common clinical approach, though it is rather subjective and qualitative and the palpation results may vary among different people. Tissue ultrasound palpation sensor (TUPS) provides a feasible solution that makes the palpation of soft tissues not subjective feeling any more. It is comprised of an ultrasound transducer together with a load cell to form the finger-sized probe. The probe is used to push against the soft tissue surface to measure the thickness and elasticity of the soft tissues. TUPS has been successfully applied to the assessment of various human tissues. Recently, we have improved TUPS, which can now be linked to personal computer (PC) via universal serial bus (USB) and provide a better user-interface. The information of ultrasound signal and indentation force is displayed on PC in real time during measurement. In this paper, we introduce the recent application of TUPS for the assessment of the transverse carpal ligament. The tissues at the carpal tunnel regions of five normal male subjects were tested using TUPS. The results showed that the average thickness of the tissues covering the carpal tunnel ligament and the tunnel region was 7.98+/-1.05 mm and 9.59+/-1.12 mm, respectively. Under a compression force of 20 N applied by a cylindrical ultrasound indentor with a diameter of 9 mm, the stiffness of the soft tissue layer and the tunnel region was 6.72+/-2.10 N/mm and 15.63+/-8.42 N/mm, respectively. It is expected that TUPS can be a potential tool for non-invasive assessment of carpal tunnel syndrome.

Algorithms↗

PubMed2005

Sonomyography: monitoring morphological changes of forearm muscles in actions with the feasibility for the control of powered prosthesis.

Electromyography (EMG) has been widely used for the assessment of musculoskeletal functions and the control of electrical prostheses, which make use of the EMG signal generated by the contraction of the residual muscles. In spite of the successful applications of EMG in different fields, it has some inherent limitations, such as the difficulty to differentiate the actions of neighboring muscles and to collect signals from deep muscles using the surface EMG. The majority of current EMG controlled prostheses can only provide sequential on-off controls using signals from two groups of muscles, so the users are required to put many conscious efforts in monitoring the speed and range of motion of the terminal devices being controlled. Recently, many alternative signals based on the detection of dimensional changes of muscles or tendons during actions have been reported. The objective of this study was to investigate the potential of the dimensional change of muscles detected using sonography for musculoskeletal assessment and control. A portable B-mode ultrasound scanner was used to collect the dynamic ultrasound images of the forearm muscles of six normally limbed young adults and three amputee subjects. A motion analysis system was used to collect the movement of the wrist angle during the experiments for the normal subjects. It was demonstrated that the morphological changes of forearm muscles during actions can be successfully detected by ultrasound and linearly correlated (R(2)=0.876+/-0.042, mean+/-S.D.) with the wrist angle. We named these sonographically detected signals about the architectural change of the muscle as sonomyography (SMG). The mean ratio between the wrist angle and the percentage deformation of the forearm muscle was 7.2+/-3.7 degrees /% for the normal subjects. The intraclass correlation coefficient (ICC) of this ratio among the three repeated tests was 0.868. The SMG signals from the residual forearms were also successfully detected when the three amputee subjects contracted their residual muscles. The results demonstrated that SMG had potentials for the musculoskeletal control and assessment.

Amputees↗

PubMed2005

Estimation of Young's modulus and Poisson's ratio of soft tissue from indentation using two different-sized indentors: finite element analysis of the finite deformation effect.

Young's modulus and Poisson's ratio of a tissue can be simultaneously obtained using two indentation tests with two different sized indentors in two indentations. Owing to the assumption of infinitesimal deformation of the indentation, the finite deformation effect of indentation on the calculated material parameters was not fully understood in the double indentation approach. However, indentation tests with infinitesimal deformation are not practical for the measurement of real tissues. Accordingly, finite element models were developed to simulate the indentation with different indentor diameters and different deformation ratios to investigate the finite deformation effect of indentation. The results indicated that Young's modulus E increased with the increase in the indentation deformation w, if the finite deformation effect of indentation was not considered. This phenomenon became obvious when Poisson's ratio v approached 0.5 and/or the ratio of indentor radius and tissue thickness a/h increased. The calculated Young's modulus could be different by 23% at 10% deformation in comparison with its real value. The results also demonstrated that the finite deformation effect to indentation on the calculation of Poisson's ratio v was much smaller. After the finite deformation effect of indentation was considered, the error of the calculated Young's modulus could be controlled within 5% (a/h = 1) and 2% (a/h = 2) for deformation up to 10%.

Connective Tissue↗

PubMed2005

Application of tissue ultrasound palpation system (TUPS) in objective scar evaluation.

One of the characteristics of hypertrophic scarring is its raised appearance. Its maturation often results in increased thickness. Therapists usually rely on subjective observation and palpation to document scar thickness. The result of these subjective assessments may reflect only the superficial scar thickness but is unable to measure the whole scar volume and thickness under the skin surface. Measurement of scar thickness using ultrasound imaging has been previously reported, but has not been commonly used in clinics due to its complex operation method and high cost. In this study, we have adopted a newly developed and user-friendly Tissue ultrasound palpation system (TUPS) for the assessment of scar thickness. It consists of a finger size palpation probe, connected to an ultrasound transducer and an in-series load cell to measure the thickness of the soft tissue over the human body. The method of operation is easy and it can be used to measure skin thickness on various parts of the body, thus reflecting the skin thickness. The reliability of the TUPS in clinical application was tested on 30 subjects with a hypertrophic scar at a local hospital. Three raters implemented two assessments on each subject to study its test-retest and inter-rater reliabilities. It was then used to assess 100 subjects with various severity of hypertrophic scar caused by trauma, scald, burn or surgery. They were assessed using TUPS as well as the Vancouver Scar Scale (VSS) for rating scar thickness, pliability, pigmentation and vascularity. Two-way mixed intra-class correlation showed a high test-retest reliability with Intraclass Correlation Coefficient (ICC)=0.98 and inter-rater reliability ICC=0.84. Fair positive correlations with VSS thickness score and VSS total score r=0.34 (p<0.05) and 0.42 (p<0.05), respectively. A significant difference between two scar type groups (50 burn scald scars and 50 surgical scars) was demonstrated (d.f.=52.94, t=3.99, p<0.01). TUPS was proved to have high inter-rater, test-retest reliability and it had a moderate correlation with the VSS that clinicians used for assessment of the scar. This system is recommended for clinical assessment of scar thickness.

Adolescent↗

PubMed2005

Ultrasonic measurement of depth-dependent transient behaviors of articular cartilage under compression.

We previously reported an ultrasound method for measuring the depth-dependent equilibrium mechanical properties of articular cartilage using quasi-static compression. The objective of this paper was to introduce our recent development for nondestructively measuring the transient depth-dependent strains of full-thickness articular cartilage specimens prepared from bovine patellae. A 50 MHz focused ultrasound transducer was used to collect ultrasound echoes from articular cartilage specimens (n=8) and sponge phantoms with open pores (n=10) during tests of compression and subsequent stress-relaxation. The transient displacements of the tissues at different depths along the compression direction were calculated from the ultrasound echoes using a cross-correlation tracking technique. An LVDT sensor and a load cell were used to measure the overall deformation of the tissue and the applied force, respectively. Results showed that the tissues inside the cartilage layer continued to move during the stress-relaxation phase after the compression was completed. In the equilibrium state, the displacements of the cartilage tissues at the depths of 1/4, 1/2, and 3/4 of the full-thickness reduced by 51%+/-22%, 54%+/-17%, and 50+/-17%, respectively, in comparison with its peak value. However, no similar phenomenon was observed in the sponge phantoms. Our preliminary results demonstrated that this ultrasound method may provide a potential tool for the nondestructive measurement of the transient depth-dependent processes involved in biological and bioengineered soft tissues as well as soft biomaterials under dynamic loading.

Animals↗

PubMed2005

Development of a portable 3D ultrasound imaging system for musculoskeletal tissues.

3D ultrasound is a promising imaging modality for clinical diagnosis and treatment monitoring. Its cost is relatively low in comparison with CT and MRI, no intensive training and radiation protection is required for its operation, and its hardware is movable and can potentially be portable. In this study, we developed a portable freehand 3D ultrasound imaging system for the assessment of musculoskeletal body parts. A portable ultrasound scanner was used to obtain real-time B-mode ultrasound images of musculoskeletal tissues and an electromagnetic spatial sensor was fixed on the ultrasound probe to acquire the position and orientation of the images. The images were digitized with a video digitization device and displayed with its orientation and position synchronized in real-time with the data obtained by the spatial sensor. A program was developed for volume reconstruction, visualization, segmentation and measurement using Visual C++ and Visualization toolkits (VTK) software. A 2D Gaussian filter and a Median filter were implemented to improve the quality of the B-scan images collected by the portable ultrasound scanner. An improved distance-weighted grid-mapping algorithm was proposed for volume reconstruction. Temporal calibrations were conducted to correct the delay between the collections of images and spatial data. Spatial calibrations were performed using a cross-wire phantom. The system accuracy was validated by one cylinder and two cuboid phantoms made of silicone. The average errors for distance measurement in three orthogonal directions in comparison with micrometer measurement were 0.06+/-0.39, -0.27+/-0.27, and 0.33+/-0.39 mm, respectively. The average error for volume measurement was -0.18%+/-5.44% for the three phantoms. The system has been successfully used to obtain the volume images of a fetus phantom, the fingers and forearms of human subjects. For a typical volume with 126 x 103 x 109 voxels, the 3D image could be reconstructed from 258 B-scans (640 x 480 pixels) within one minute using a portable PC with Pentium IV 2.4 GHz CPU and 512 MB memories. It is believed that such a portable volume imaging system will have many applications in the assessment of musculoskeletal tissues because of its easy accessibility.

Equipment Design↗

PubMed2005

A novel noncontact ultrasound indentation system for measurement of tissue material properties using water jet compression.

This study is aimed to develop a novel noncontact ultrasonic indentation system for measuring quantitative mechanical properties of soft tissues, which are increasingly important for tissue assessment and characterization. The key idea of this method is to use a water jet as an indenter to compress the soft tissue while at the same time as a medium for an ultrasound beam to propagate through. The use of water jet indentation does not require a rigid compressor in front of the focused high frequency ultrasound transducer to compress the tissue, so that the additional attenuation caused by the rigid compressor and the strong echoes reflected from its surfaces can be avoided. The indentation deformation was estimated from the ultrasound echoes using a cross-correlation algorithm and the indentation force was calculated from the water pressure measured inside the water pipe. Experiments were performed on uniform tissue-mimicking phantoms with different stiffness. The Young's moduli and Poisson's ratios of these phantoms were measured using a uniaxial ultrasound compression system. The ratio of the indentation pressure to the tissue relative deformation was obtained from the water indentation. This ratio was well correlated with the Young's modulus (r = 0.87). The results also demonstrated that the water indentation approach could differentiate materials with different stiffness in a combined phantom (288 kPa and 433 kPa). This novel noncontact water indentation approach could be potentially used for the measurement of the elasticity of small samples and with a fast scanning speed.

Algorithms↗

PubMed2005

A new scanning approach for limb extremities using a water bag in freehand 3-D ultrasound.

3-D ultrasound (US) can significantly improve the visualization of musculoskeletal tissues, such as residual limbs, feet and hands. Traditionally, mechanical scanning is normally required to obtain the entire volume of these limb extremities. In this paper, a new scanning approach using a water bag was described to collect the complete volume of various tissues surrounding bones. The water bag was used to contain the limb extremity and the scanning was conducted on its external surface from different directions. The recorded 2-D US images containing complete anatomic information surrounding the bones from different directions were used to form full 3-D volumes of the limb extremities. A plastic auxiliary apparatus was designed to hold the water bag and support the subject's limb part with an armrest. A corresponding algorithm was proposed to remove invalid image information within each sweep by a separating plane defined semiautomatically. Two phantoms were used to test the repeatability and accuracy of the imaging. The distance between two plastic bands attached to a plastic tube filled with US gel measured by a micrometer and from the four reconstructed volumes were 39.03 +/- 0.36 mm and 39.2 +/- 0.5 mm, respectively. The diameter, height and volume of a silicone cylinder phantom measured for the 10 reconstructed volumes were 40.2 +/- 1.4 mm, 12.9 +/- 1.0 mm and 16400 +/- 1600 mm(3), respectively. They agreed with the corresponding results obtained by the micrometer, which were 41.29 +/- 0.13 mm, 12.98 +/- 0.17 mm and 17370 +/- 140 mm(3), respectively. The reconstructed volumes of the two phantoms, a chicken leg in vitro, and human fingers in vivo were also reported. The preliminary results obtained in this study demonstrated that this new scanning approach should have potential for the 3-D US imaging of musculoskeletal extremities using freehand scanning.

Algorithms↗

PubMed2005

Vital sign monitoring for elderly at home: development of a compound sensor for pulse rate and motion.

This paper describes the development of a miniaturized wearable vital sign monitor which is aimed for use by elderly at home. The development of a compound sensor for pulse rate, motion, and skin temperature is reported. A pair of infrared sensor working in reflection mode was used to detect the pulse rate from various sites over the body including the wrist and finger. Meanwhile, a motion sensor was used to detect the motion of the body. In addition, the temperature on the skin surface was sensed by a semiconductor temperature sensor. A prototype has been built into a box with a dimension of 2 x 2.5 x 4 cm3. The device includes the sensors, microprocessor, circuits, battery, and a wireless transceiver for communicating data with a data terminal.

Aged↗

PubMed2004

High resolution ultrasound elastomicroscopy imaging of soft tissues: system development and feasibility.

Research in elasticity imaging typically relies on 1-10 MHz ultrasound. Elasticity imaging at these frequencies can provide strain maps with a resolution in the order of millimetres, but this is not sufficient for applications to skin, articular cartilage or other fine structures. We developed a prototype high resolution elastomicroscopy system consisting of a 50 MHz ultrasound backscatter microscope system and a calibrated compression device using a load cell to measure the pressure applied to the specimen, which was installed between a rigidly fixed face-plate and a specimen platform. Radiofrequency data were acquired in a B-scan format (10 mm wide x 3 mm deep) in specimens of mouse skin and bovine patellar cartilage. The scanning resolution along the B-scan plane direction was 50 microm, and the ultrasound signals were digitized at 500 MHz to achieve a sensitivity better than 1 microm for the axial displacement measurement. Because of elevated attenuation of ultrasound at high frequencies, special consideration was necessary to design a face-plate permitting efficient ultrasound transmission into the specimen and relative uniformity of the compression. Best results were obtained using a thin plastic film to cover a specially shaped slit in the face-plate. Local tissue strain maps were constructed by applying a cross-correlation tracking method to signals obtained at the same site at different compression levels. The speed of sound in the tissue specimen (1589.8+/-7.8 m s(-1) for cartilage and 1532.4+/-4.4 m s(-1) for skin) was simultaneously measured during the compression test. Preliminary results demonstrated that this ultrasound elastomicroscopy technique was able to map deformations of the skin and articular cartilage specimens to high resolution, in the order of 50 microm. This system can also be potentially used for the assessment of other biological tissues, bioengineered tissues or biomaterials with fine structures.

Animals↗

PubMed2004

Indentation test of soft tissues with curved substrates: a finite element study.

Indentation is a commonly used approach to measure the mechanical properties of soft tissues, such as articular cartilage and limb tissues. The Young's modulus of tissue can be calculated from the indentation test using a mechanical model, where the soft tissue is normally assumed to have a flat substrate. In this study, a series of 2D finite element models were established to investigate the effects of bones with various curvatures embedded in the soft tissues during an indentation test. For each curvature of the hard substrate, the errors in the calculation of the Young's modulus were estimated for different indentation depths (0-10%) and aspect ratios a/h of the indentor diameter and the tissue thickness (0.2-2 in seven steps). The radius ratio a/R of the indentor and the curved substrate ranged from 0 to 0.38 in nine steps. Results showed that the error in calculation of the Young's modulus increased by 21.2% when the curvature a/R of the bone increased from 0 to 0.38 (under the condition of a/h=1.0, Poisson's ratio v=0.45). The error increased from 6.0 to 18.2% when the tissue thickness increased from 0.2 to 2 (a/R=0.18, v=0.45). It was found that the error in the Young's modulus calculation caused by the curved hard substrates could be corrected by a single factor for different indentation depths. This factor depends on the Poisson's ratio, the aspect ratio a/h and the radius ratio a/R.

Bone and Bones↗

PubMed2004

Dynamic depth-dependent osmotic swelling and solute diffusion in articular cartilage monitored using real-time ultrasound.

The objective of this study was to investigate the feasibility of ultrasonic monitoring for the transient depth-dependent osmotic swelling and solute diffusion in normal and degenerated articular cartilage (artC) tissues. Full-thickness artC specimens were collected from fresh bovine patellae. The artC specimens were continuously monitored using a focused beam of 50 MHz ultrasound (US) during sequential changes of the bathing solution from 0.15 mol/L to 2 mol/L saline, 0.15 mol/L saline, 1 mg/mL trypsin solution, 0.15 mol/L saline, 2 mol/L saline and back to 0.15 mol/L saline. The transient displacements of US echoes from the artC tissues at different depths were used to represent the tissue deformation and the NaCl diffusion. The trypsin solution was used selectively to digest the proteoglycans in artC. It was demonstrated that high-frequency US was feasible for monitoring the transient osmotic swelling, solute transport and progressive degeneration of artC in real-time. Preliminary results showed that the normal bovine patellar artC shrank during the first several minutes and then recovered to its original state in approximately 1 h when the solution was changed from 0.15 mol/L to 2 mol/L saline. Degenerated artC showed neither shrinkage nor recovery during the same process. In addition, a dehydrated-hydrated artC specimen showed much stronger shrinkage and it resumed the original state when the solution was changed from 2 mol/L back to 0.15 mol/L saline. The diffusion of NaCl and the digestion process of proteoglycans induced by trypsin were also successfully monitored in real-time.

Animals↗

PubMed2004

Measurement of depth-dependence and anisotropy of ultrasound speed of bovine articular cartilage in vitro.

The inhomogeneous and anisotropic mechanical properties and structural components of articular cartilage (artC) may cause complex acoustic properties in this important tissue. In this study, we used 50-MHz ultrasound (US) to measure in vitro the depth-dependence and anisotropy of the US speed of artC collected from the bovine patellae. The US speeds of 18 disk artC specimens sampled from 18 different patellae were measured in two orthogonal directions. One full-thickness layer (n=18) and three horizontal slices (n=18 x 3) with approximately equal thickness were prepared from each artC disk and measured with the US beam perpendicular to the artC surface. One full-thickness vertical slice (n=10) was measured at different depths with the US beam parallel to the artC surface. The measured US speeds of artC in the two orthogonal directions were significantly different (p < 0.001). The US speeds also significantly increased with the increase of tissue depth for both measurement directions (p < 0.001). The US speeds of artC from the superficial to deep regions were 1518 +/- 17 (mean + SD), 1532 +/- 26 and 1554 +/- 42 m/s for the US beam parallel to the artC surface, and 1574 +/- 29, 1621 +/- 34 and 1701 +/- 36 m/s for the beam perpendicular to the artC surface. The sound speed of the full-thickness layer was 1636 +/- 25 m/s. The results suggested that the depth-dependence and anisotropy of the US speed in artC should be taken into account when US is used for the artC measurement. It was also demonstrated in this study, using additional specimens (5 x 2), that the swelling of artC after detaching from its subchondral bone could cause the change of its sound speed.

Animals↗

PubMed2002

An ultrasonic measurement for in vitro depth-dependent equilibrium strains of articular cartilage in compression.

The equilibrium depth-dependent biomechanical properties of articular cartilage were measured using an ultrasound-compression method. Ten cylindrical bovine patella cartilage-bone specimens were tested in compression followed by a period of force-relaxation. A 50 MHz focused ultrasound beam was transmitted into the cartilage specimen through a remaining bone layer and a small hole at the centre of a specimen platform. The ultrasound echoes reflected or scattered within the articularcartilage were collected using the same transducer. The displacements of the tissues at different depths of the articular cartilage were derived from the ultrasound echo signals recorded during the compression and the subsequent force-relaxation. For two steps of 0.1 mm compression, the average strain at the superficial 0.2 mm thick layer (0.35 +/- 0.09) was significantly (p < 0.05) larger than that at the subsequent 0.2 mm thick layer (0.05 +/- 0.07) and that at deeper layers (0.01 +/- 0.02). It was demonstrated that the compressive biomechanical properties of cartilage were highly depth-dependent. The results suggested that the ultrasound-compression method could be a useful tool for the study of the depth-dependent biomechanical properties of articular cartilage.

Animals↗

PubMed2001

Measurement of the layered compressive properties of trypsin-treated articular cartilage: an ultrasound investigation.

An ultrasound-compression system has been developed for the study of the layered biomechanical properties of articular cartilage. Cartilage specimens harvested from the bovine patella groove, with and without trypsin digestion, were tested using this system. It was noted that a large ultrasound reflection can be detected in the interface of the trypsin digestion front. This ultrasound reflection signal was used to differentiate the deformations of different portions of the cartilage throughout its depth when a load was applied. The equilibrium compression moduli of the digested, undigested and entire portions of articular cartilage were measured. The modulus of the cartilage without any digestion was 660+/-230 kPa. After 1h digestion with 1 mg ml(-1) trypsin solution, the thickness of the digested portion was 0.50+/-0.06m, and the modulus of the entire cartilage layer changed to 125+/-42kPa. The moduli of the digested and undigested portions were 58+/-24 kPa and 470+/-31 kPa, respectively. Similar results were obtained for the cartilage with trypsin digestion for 2 h.

Animals↗

PubMed2001

Analysis of the CYP2D6 gene polymorphism and enzyme activity in African-Americans in southern California.

Despite its importance in drug metabolism and disease susceptibility, CYP2D6 activity and genetic polymorphism have rarely been investigated in African-American populations. In order to bridge this gap, we examined the genotype and phenotype of the enzyme in 154 African-American (AA) and 143 Caucasian (C) normal volunteers. AAs are significantly more likely to possess *17 and *5, but less likely to have *4. Overall, the two groups were similar in their CYP2D6 activity as measured with dextromethorphan as the probe (metabolic ratio 2.21 +/- 0.78 for AAs; 2.11 +/- 0.86 for Cs; t = 1.02, NS). Two of four AAs and six of seven Cs were classified as poor metabolizers and have two nonfunctioning alleles. CYP2D6 activity is determined by *17, *4, *5 and age in AAs (r2 = 0.33, f = 18.8, P < 0.001) and by *4 and *XN in Cs (r2 = 0.14, f = 10.8, P < 0.001). These results support previous findings demonstrating the importance of *17 in determining CYP2D6 activity in AAs.

Adult↗

PubMed2001

[Clinical study on conducting physical exercise in lowering blood pressure of hypertensive patients and influencing their endocrine hormones].

OBJECTIVE: To explore the mechanism of conducting physical exercise to lower blood pressure of hypertensive patients, relieve their symptoms and influence the cardiovascular endocrine hormone. METHODS: One hundred and twenty-five patients with II or III stage hypertension were divided into the experimental group and the control group and observed. The comparison of conditions before and after treatment, and between experimental and control groups was carried out. RESULTS: The effect in lowering blood pressure and relieving symptoms in the experimental group were obviously better than those in the control group, P < 0.05. Angiotensin-II (AT-II) level much reduced after the exercise experiment, P < 0.05. Peripheral renin activity (PRA) level had a tendency of reduction, but atrial natriuetic factor (ANF) and 6-keto-prostaglandin F1 alpha (6-k-PGF1 alpha) showed a tendency of increasing. CONCLUSION: Physical exercise combined with medical treatment could control the symptoms of hypertensive patients, in some of them could gradually using the way of doing physical exercise to replace the hypotensive medicament, the effect of the combined treatment can be obtained within a month. The change of cardiovascular endocrine hormone indicated that the physical exercise can be helpful in lowering blood pressure and improving blood circulation in hypertensive patients.

6-Ketoprostaglandin F1 alpha↗