Shizhong Jiang

State Key Laboratory of Medical Genetics of China, Ch’ang-sha-shih, Hunan, China

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Publications (10)10.91 Total impact

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    ABSTRACT: Skeletal unloading induced by disuse or immobilization causes a decrease in bone mass and strength. We investigated the relationship between whole-body vibration (WBV) and resistance exercise (RE) in preventing bone loss induced by 8-week hindlimb unloading in young male rats. Sixty male Wistar rats were assigned randomly to 6 groups: age-matched control group (CON, n = 10), hindlimb unloading group (HU, n = 10), hindlimb unloading + standing group (HU + ST, n = 10), hindlimb unloading + WBV group (HU + WBV, n = 10), hindlimb unloading + RE group (HU + RE, n = 10) and hindlimb unloading + WBV + RE group (HU + WBV + RE, n = 10). After 8-week hindlimb unloading, micro-CT scanning and three-point bending test were performed in the femur. Sera were collected for analysis of bone formation and resorption markers. Compared with HU group, WBV, RE and the combination of WBV and RE (WBV + RE) significantly improved (P < 0.01) one repetition maximum (1RM) (expressed as the percentage change from baseline, HU: -23%, HU + WBV: 21%, HU + RE: 48%, HU + WBV + RE: 51%), and maintained (P < 0.05) cancellous volumetric bone mineral density (vBMD) and trabecular structure. No difference of cortical vBMD was found among all groups (P > 0.05). WBV had no effects on biomechanical properties of the femur diaphysis (P > 0.05). RE and WBV + RE significantly increased maximum load and cross-sectional moment of inertia of the femur diaphysis in hindlimb unloading rats (P < 0.05). There was an interaction between WBV and RE in improving cancellous bone. These results demonstrate that WBV and RE interactively maintain cancellous structure and vBMD, and independently partially mitigate the reduction of bone strength in long-term hindlimb unloading rats.
    Arbeitsphysiologie 02/2012; 112(11):3743-53. · 2.66 Impact Factor
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    ABSTRACT: We quantified the impact of 60-day head-down bed rest (HDBR) with countermeasures on arterial and venous response to tilt. Twenty-one males: 7 control (Con), 7 resistive vibration exercise (RVE) and 7 Chinese herb (Herb) were assessed. Subjects were identified as finisher (F) or non-finishers (NF) at the post-HDBR 20-min tilt test. The cerebral (MCA), femoral (FEM) arterial flow velocity and leg vascular resistance (FRI), the portal vein section (PV), the flow redistribution ratios (MCA/FEM; MCA/PV), the tibial (Tib), gastrocnemius (Gast), and saphenous (Saph) vein sections were measured by echography and Doppler ultrasonography. Arterial and venous parameters were measured at 3-min pre-tilt in the supine position, and at 1 min before the end of the tilt. At post-HDBR tilt, MCA decreased more compared with pre-HDBR tilt in the Con, RVE, and Herb groups, the MCA/FEM tended to decrease in the Con and Herb groups (not significant) but remained stable in the RVE gr. FRI dropped in the Con gr, but remained stable in the Herb gr and increased in the RVE gr. PV decreased less in the Con and Herb groups but remained unchanged in the RVE gr. MCA/PV decreased in the Con and Herb groups, but increased to a similar extent in the RVE gr. Gast section significantly increased more in the Con gr only, whereas Tib section increased more in the Con and Herb groups but not in the RVE gr. The percent change in Saph section was similar at pre- and post-HDBR tilt. In the Con gr, vasoconstriction was reduced in leg and splanchnic areas. RVE and Herb contributed to prevent the loss of vasoconstriction in both areas, but the effect of RVE was higher. RVE and Herb contributed to limit Gast distension whereas only RVE had a protective effect on the Tib.
    PLoS ONE 01/2012; 7(3):e32854. · 3.53 Impact Factor
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    ABSTRACT: Check if the Temporal flow response to Tilt could provide early hemodynamic pattern in the minutes preceding a syncope during the Tilt test performed after a 60-d head down bedrest (HDBR). Twenty-one men divided into 3 groups [Control (Con), Resistive Vibration (RVE) and Chinese Herb (Herb)] underwent a 60 day HDBR. Pre and Post HDBR a 20 min Tilt identified Finishers (F) and Non Finishers (NF). Cerebral (MCA), Temporal (TEMP), Femoral (FEM) flow velocity, were measured by Doppler during the Tilt. Blood pressure (BP) was measured by arm cuff and cardiopress. Four of the 21 subjects were NF at the post HDBR Tilt test (Con gr:2, RVE gr: 1, Herb gr: 1). At 1 min and 10 s before end of Tilt in NF gr, FEM flow decreased less and MCA decreased more at post HDBR Tilt compared to pre (p<0.05), while in the F gr they changed similarly as pre. In NF gr: TEMP flow decreased more at post HDBR Tilt compared to pre, but only at 10 s before the end of Tilt (P<0.05). During the last 10 s a negative TEMP diastolic component appeared which induced a drop in mean velocity until Tilt arrest. The sudden drop in TEMP flow with onset of a negative diastolic flow preceding the decrease in MCA flow confirm that the TEMP vascular resistance respond more directly than the cerebral one to the cardiac output redistribution and that this response occur several seconds before syncope.
    PLoS ONE 01/2011; 6(10):e22963. · 3.53 Impact Factor
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    ABSTRACT: The objective of this study was to analyse and evaluate the protection function and feasibility of two types of human neck safety equipment under unusual landings. Human head and neck dynamic responses were simulated by constructing a mechanical model of the human-seat system, which was equipped with two kinds of head support systems. The force and moment in the human neck were calculated. The protection function of the head support systems was evaluated according to the injury criteria HIC (head injury criterion) and Nij (neck injury criterion). Two kinds of safety equipment were used under unusual landing. The results of the experiment showed that Nij is smaller than the injury criterion limits under normal landings, and that the safety equipment provided effective protection. The safety equipment was confirmed to reduce the degree of neck injuries resulting from unusual landing impacts.
    International Journal of Crashworthiness - INT J CRASHWORTHINESS. 01/2011;
  • Bingkun Liu, Honglei Ma, Shizhong Jiang
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    ABSTRACT: Impact acceleration is one of the factors to which human body is exposed in aerospace exploring. When the impact level is greater than human tolerance, it usually results in human injuries which may be fatal. Therefore, in order to reduce or avert the risk of serious injury from crash impact, human tolerance to impact acceleration is a crucial consideration in aircraft since the beginning of aviation. The study on human tolerance to impact acceleration has become a cynosure in the realm of modern biomechanics. So this paper reviews the progress of the researches.
    Sheng wu yi xue gong cheng xue za zhi = Journal of biomedical engineering = Shengwu yixue gongchengxue zazhi 04/2010; 27(2):444-7.
  • Bingkun Liu, Honglei Ma, Shizhong Jiang, Huiliang Du
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    ABSTRACT: When a spacecraft lands on the earth by parachute, the crewmen will be subjected to a high-level landing impact which could cause their body injuries in case of emergency. The purpose of this investigation was to analyse the human neck injury risk under the high-level landing impact, and to provide useful information for the protection design of the human-seat system in the spacecraft. On the basis of impact test, a mechanical model of the human-seat system was developed, and the acceleration responses at the seat and cushion were simulated using the finite element method. After the model was calibrated and validated, the forces and moments in the human neck were calculated. The degree of the human neck injury can be judged according to the standard of the human neck injury index (N ij < 1). The results showed that when both horizontal and vertical dropping velocity reach 7.5 m/s, the compressive force and extension moment in the human neck were, respectively, 6.58 kN and 100 Nm; and the injury index of the human neck was 1.81 (more than the critical value 1). It is concluded that under the high-level landing impact, the first reason for cervical fracture is the compressive force, and the second is the extension moment. It is necessary to take measures to reduce them to levels less than tolerance limits.
    International Journal of Crashworthiness 12/2009; 14(6):585-590.
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    ABSTRACT: Hindlimb unloading can induce the cardiac atrophy and diminished cardiac function, however, the mechanisms responsible for which remain elusive. The chronic volume unloading of heart, which decreases the local mechanical stress, may lead to cardiac atrophy after hindlimb unloading. Many studies showed that integrin signaling, p38 MAPK, Heat shock protein 27 and cytoskeleton involved in the hypertrophic growth induced by mechanical stress. However, the mechanisms responsible for cardiac atrophy after hindlimb unloading are still unclear. In this study, we used the tail-suspended, hindlimb unloading rat model to simulate the effects of microgravity. Western blot analysis was used to detect the protein expression of Heat shock protein 27, focal adhesion kinase, p38 MAPK and their phosphorylation levels in rat cardiac muscle after 14d hindlimb unloading. The results showed that the phosphorylation levels of both Heat shock protein 27 and p38 MAPK were decreased significantly in rat cardiac muscle after hindlimb unloading. However, the phosphorylation level of focal adhesion kinase was not decreased significantly. The results suggested that Heat shock protein 27, the downstream of p38 MAPK, might play a critical role in the cardiac atrophy in response to simulated microgravity induced by hindlimb unloading.
    Advances in Space Research 01/2009; · 1.18 Impact Factor
  • Bingkun Liu, Honglei Ma, Shizhong Jiang
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    ABSTRACT: The purpose of this study was to observe the acceleration responses of the key body segments to the landing impact in selected body positions. 5 young male subjects in 45 experiments were voluntarily exposed to the peak from 4 to 10g and duration from 50 to 80 ms acceleration pulses at 20° supine angle and the peak 10g and duration 50 ms impact at the supine angles from 20 to 60°. The acceleration responses on the dropping platform of the impact tower, the seat, the subject's head, shoulder, chest and ilium, as well as ECG of the subject were measured. The results demonstrated that the acceleration peaks of these key body segments in the chest-back direction had a highly significant positive correlation with the impact level. But their correlation in the head-foot direction was lower than that in the chest-back direction except that of the head. The acceleration peaks of these key body segments in the chest-back direction had a negative correlation with the supine angle. But the acceleration peaks of ilium in the head-foot direction had a positive correlation with the supine angle, and that of the chest almost bore no correlation. There were nonlinear relations between acceleration peak and supine angle at the head and the shoulder respectively, and the acceleration peaks of the head and shoulder in the head-foot direction reached minimum at about 40° supine angle. It is concluded that the acceleration responses of the key body segments demonstrate different properties between the chest-back direction and the head-foot direction. It is recommended that the angle of the seat back be adjusted about 40° before the spacecraft landing in order to prevent potential head injuries.
    Aerospace Science and Technology. 01/2008;
  • Ming Yuan, Shizhong Jiang, Zhili Li, Min Yuan, Weijun Dong
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    ABSTRACT: Many studies have shown that simulated microgravity induced by hindlimb unloading can decrease the contractility of rat cardiac muscle however the mechanisms responsible for which remain unclear Actin polymerization which can be regulated by Hsp27 has important role in the transmission of stress force during the contraction of cardiac muscle In this study western blot analysis was used to detect the expression of Hsp27 and phosphorylated Hsp27 FAK and phosphorylated FAK P38 MAPK and phosphorylated P38 MAPK in rat cardiac muscle after 14d hindlimb unloading The results showed that the phosphorylation levels of both Hsp27 and P38 MAPK were declined significantly which may decrease actin polymerization and inhibit the transmission of stress force during the contraction of rat cardiac muscle after hindlimb unloading However the phosphorylation level of FAK was not declined significantly in cardiac muscle The results suggested that the declined phosphorylation level of Hsp27 which may be ascribable to the decline of contractility of rat cardiac muscle after 14d hindlimb unloading may be induced by the declined phosphorylation level of P38 MAPK but not phosphorylation level of FAK
    01/2006;
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    Ming Yuan, Zhili Li, Desheng Wang, Shizhong Jiang
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    ABSTRACT: The present study tested the hypothesis that the role of ERK in phasic and tonic contractile responses is declined by hindlimb unloading (HU) in rat femoral arteries. Male Wistar rats were randomised into HU and Control group (n=7). After 14d, the femoral arteries were isolated and cut into 3-mm ring segments. In the absence or presence of PD98059(MEK inhibitor), contractile response to NE(10μM) was measured in Krebs solution in a tissue bath at 37°C, isometric tension were recorded with Powerlab system. The area under curve (AUC), phasic and tonic contractile responses between two groups were compared. After 14d-HU, the AUC, phasic and tonic NE-induced contractile responses were declined compared with controls. PD98059 did not affect the AUC in arteries from HU, but significantly decreased the AUC in arteries from control (100±7.1% vs. 61.18±11.3%, P<0.05). In contrast to control, the inhibitory ratio of PD98059 was significantly lower in phasic (7.42±3.24% vs. 33.59± 9.19%, P=0.0198) and tonic (26.93±3.78% vs. 46.75±5.67%, P=0.0131) contractile responses of HU group. Moreover, the inhibitory ratio of PD98059 wasn't significantly different between the phasic and tonic contractile responses in control group (P=0.2464). But for HU group, the difference was statistically significant (P=0.002). We demonstrated that the role of ERK was declined in both phasic and tonic contractile responses in rat femoral arteries after hindlimb unloading. Simulated microgravity induced by HU may attenuate the contractile responses of femoral arteries by inhibiting the role of ERK in thick and thin filament regulatory pathways.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 01/2005; 1:967-70.

Publication Stats

8 Citations
10.91 Total Impact Points

Institutions

  • 2011
    • State Key Laboratory of Medical Genetics of China
      Ch’ang-sha-shih, Hunan, China
  • 2008
    • Fourth Military Medical University
      Xi’an, Liaoning, China