Shear modulus measurement of biological tissues based on Zener model / 医用生物力学

Objective To measure the shear modulus of biological tissues by using Zener model so as to overcome the limitation of Voigt model-based ultrasound vibrometry, and to provide effective approaches of tissue characterization. Methods The mechanical constitutive relation-based shear wave propagation velocity formula was utilized to estimate the shear modulus in terms of the velocities at multiple frequencies via mathematical methods. To obtain shear wave velocities in different objects, experiments were conducted by using different consistencies-based gelatin models and thermally damaged porcine livers as subjects, in which shear waves were induced by ultrasound radio forces. Results Voigt and Zener models were utilized to fit the velocities respectively. The Zener model exhibited higher fitting accuracy than the Voigt model, and the shear modulus could well distinguish gelatin models with different consistencies or porcine livers of different damage degrees. Conclusions The method in this paper provides a potential means of measuring the shear modulus of biological tissues non invasively, which is very promising for tissue characterization and disease diagnosis in medicine.

Facial pain induces the alteration of transient receptor potential vanilloid receptor 1 expression in rat trigeminal ganglion / 神经科学通报·英文版

<p><b>OBJECTIVE</b>To investigate the involvement of transient receptor potential vanilloid receptor 1 (TRPV1) in the facial inflammatory pain in relation to thermal hyperalgesia and cold pain sensation.</p><p><b>METHODS</b>Facial inflammatory pain model was developed by subcutaneous injection of turpentine oil (TO) into rat facial area. Head withdrawal thermal latency (HWTL) and head withdrawal cold latency (HWCL) were measured once a day for 21 d after TO treatment using thermal and cold measurement apparatus. The immunohistochemical staining, cell-size frequency analysis and the survey of average optical density (OD) value were used to observe the changes of TRPV1 expression in the neurons of the trigeminal ganglion (TG), peripheral nerve fibers in the vibrissal pad, and central projection processes in the trigeminal sensory nuclei caudalis (Vc) on day 3, 5, 7, 14, and 21 after TO injection.</p><p><b>RESULTS</b>HWTL and HWCL decreased significantly from day 1 to day 14 after TO injection with the lowest value on day 5 and day 3, respectively, and both recovered on day 21. The number of TRPV1-labeled neurons increased remarkably from day 1 to day 14 with a peak on day 7, and returned back to the normal level on day 21. In control rats, only small and medium-sized TG neurons were immunoreactive (IR) to TRPV1, and the TRPV1-IR terminals were abundant in both the vibrissal pad and the Vc. Within 2 weeks of inflammation, the expression of TRPV1 in small and medium-sized TG neurons increased obviously. Also the TRPV1 stained terminals and fibers appeared more frequent and denser in both the vibrissal pad skin and throughout laminae I and the outer zone of laminae II (IIo) of Vc.</p><p><b>CONCLUSION</b>Facial inflammatory pain could induce hyperalgesia to noxious heat and cold stimuli, and result in increase of the numbers of TRPV1 positive TG neurons and the peripheral and central terminals of TG. These results suggest that the phenotypic changes of TRPV1 expression in small and medium-sized TG neurons and terminals might play an important role in the development and maintenance of TO-induced inflammatory thermal hyperalgesia and cold pain sensation.</p>

The comparisons on total RNA from different source-original neurons applied in LMPC / 神经科学通报·英文版

Objective To compare the quality and quantity of total RNA from different source-original neurons applied in LMPC technique. Methods (1) Aglient 2100 bioanalyzer and RT-PCR were used to check the concentration and fragmentation of total RNA from unfixed, temporal fixed and fixed 12 h hypothalamus sections; (2) Different neurons of PVN and SON were collected by LMPC, CRH, TRH, AVP, OT mRNA level were measured by RT-PCR; (3) Labeled neurons by injecting CTB into stomach and non-labeled neurons in DMV collected by LMPC were checked for house keeping genes by RT-PCR. Results (1) Unfixed section had higher concentration and better quality of total RNA compared with fixed sections applied in LMPC; relative short amplicons such as GAPDH, NSE, MCH and MC4R were successfully obtained from fixed and unfixed and long amplicon of GR can only be obtained from unfixed material; (2) In mangocellular PVN and SON the expressions of AVP and OT were more special than those in the parvocellular PVN. Oppositely, the expressions of CRH, TRH in the parvocellular were more special than the other two; (3) The expressions of house keeping genes had no significant difference between labeled and non-labeled DMV neurons. Conclusion The quality and quantity of total RNA from unfixed brain tissues were better than fixed tissues applied in LMPC and the CTB tracer which may differentiate neurons had no significant effect on physiology of the neurons applied in LMPC. The results showed that the LMPC technique is suitable for the qualitative and quantitative study on individual neurons at mRNA level.

Preparing of Al2O3/ZrO2 composite dental ceramics through isostatic pressing technology / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To find out how to prepare high-density dental ceramics through isostatic pressing so that sintering shrinkage will be reduced.</p><p><b>METHODS</b>To prepare Al2O3/ZrO2 composite powder first, then to mold through dry-pressing, and to shape the green-body through isostatic pressing. The green-bodies were sintered at the temperature of 1 400 degrees C and kept at the temperature for different period of time (2 h, 3 h, 4 h). After that, the density and fracture strength were measured and the microstructure observed by scanning electron microscope (SEM).</p><p><b>RESULTS</b>The sample product's density, line-shrinkage, and fracture strength of ceramics was rising with the sintering time lengthened. The sample product kept under the temperature of 1 400 degrees C for 4 hours, the fracture strength was (497.27 +/- 78.45) MPa and glass phase distributed evenly in the ceramics and the grains were integrated owing to the glass phase. The longer the sintering time, the more even the microstructure was.</p><p><b>CONCLUSION</b>The sintering quality and the efficiency were improved through isostatic pressing.</p>

Characteristics of P2X purinoceptors in the membrane of rat trigeminal ganglion neurons / 生理学报

The characteristics of purinoceptors in the membrane of rat trigeminal ganglion (TG) neurons were studied by using whole- cell patch clamp technique. The results showed that most of neurons examined (78.9%, 142/180) were responsive to ATP in a concentration-dependent manner; the others (21.1%, 38/180) were ATP insensitive. Of the ATP-sensitive cells, the majority (95.1%, 135/142) responded to ATP with an inward current, a few (2.1%, 3/142) with an outward current, and the rest (2.8%, 4/142) with biphasic current. Small sized cells (<30 mum) responded to ATP with a rapid desensitizing inward current and were highly sensitive to vanilloid; the medium sized cells (30~40 mum) responded to ATP with slow desensitizing inward current and were not sensitive to vanilloid; while the majority of large sized cells (>40 mum) did not respond to ATP and vanilloid. The waveform of ATP-activated inward currents was related to the cell diameter. The I-V curves for both small and medium sized cells manifested obvious inward rectification. Furthermore, we studied the kinetic features of ATP-activated currents and the effects of P2 purinoceptor agonists and antagonists on I(ATP). The findings suggest that ATP receptor-ion channels are expressed differently among different types of rat TG neurons.