Biomedical subjects

Li-fan Zhang

Publications and source records attributed to Li-fan Zhang.

3 recordsLinked to original sources

PubMed2002

[Recent advances in multi-variate and multi-dimensional analysis of heart rate variability and blood pressure variability].

Heart rate variability (HRV) and blood pressure variability (BPV) reflect the modulation activity of autonomic nervous system on cardiovascular function. There have been important advances in multi-variate, multi-dimensional and dynamic analysis of HRV and BPV during recent years. Modern signal processing methods, such as multi-variate system identification, time-frequency analysis and nonlinear dynamics analysis, could be adopted in the risk prediction, severity evaluation and therapeutic treatment assessment of cardiovascular diseases. These new methods might also be useful in special environmental medicine.

Aerospace Medicine↗

PubMed2002

[Decrease in tetanic tension in 4-week tail-suspended rat soleus and analysis of its underlying mechanisms].

Objective. To observe the dynamic changes in tetanic tension in 4-week tail-suspended rat soleus (SOL) and extensor digitorum longus muscle (EDL) and to elucidate its underlying mechanisms. Method. After 4 weeks of tail suspension SOL and EDL of the rats were isolated and perfused. Their isometric twitch and tetanic tensions were recorded. Result. Atrophy occurred in the SOL, but not in the EDL. The maximum twitch tension (Pt) decreased significantly and was more dependent on stimulation voltage in SOL of tail-suspended rat. Time to maximum twitch tension (TPT) and time from maximum twitch tension to half relaxation (TR50) were reduced in the SOL. Pt also decreased in the EDL, but TPT and TR50 did not change in the EDL. The maximum tetanic tension reduced in SOL and EDL of tail-suspended rats. The decline rate of tetanic tension in SOL was faster than the control. The profile of tetanic contraction curve in atrophic SOL approached that in EDL. Conclusion. The above results suggested that the underlying mechanisms of reduced maximum twitch and tetanic tension in 4-week tail-suspended rat SOL may involve the reduction in number of cross-bridge per cross-section area or force produced per cross-bridge. The rapid decline rate in atrophic SOL may be related to the shift in myosin heavy chain and troponin I isoforms or to decrease in excitability.

Animals↗

PubMed2002

[A study on gene expression of angiotensin receptors in arteries from tail-suspended rats].

Objective. To investigate whether simulated microgravity [correction of microgravtiy] can result in alterations of mRNA expression of angiotensin receptors in rat arteries. Method. Rats were divided into simulated microgravity group and synchronous control group. Simulated microgravity rats were subjected to tail-suspension for 4-wk to simulate the effect of weightlessness. Result. Results from RT-PCR demonstrated that mRNAs of angiotensin II receptors, AT1a, AT1b, and AT2 were expressed in carotid arteries, abdominal aorta and femoral arteries, whereas only mRNAs of AT1a and AT1b were expressed in basilar arteries. There were no significant differences between the simulated-microgravity and control rats in the expression of mRNAs of AT1a, AT1b, and AT2 in these arteries. Conclusion. Angiotensin II receptors may play no regulatory role in the occurrence of the differentiated vascular adaptation during simulated microgravity.

Adaptation, Physiological↗