Establishment of rat model of retinal branch vein occlusion by photochemical method and correlational research / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To investigate the natural course and adverse event of branch retinal vein occlusion (BRVO) rat model induced by laser photochemical method. METHODS: Thirty SD (Sprague Dawley) rats were administrated Bangladesh via tail vein. Then 532nm laser (80mW, 100μ m and 100ms) was performed on retinal vein secondary bifurcation of bitamporal optic disk for 50 spots. Electroretinogram (ERG), fundus fluorescein angiography ( FFA), optical coherence tomography (OCT) and fundus (fluorescein) photograph were applied on 1, 3, 5, 7, 10, 14 and 21d after BRVO model constructed. Two rats were sacrificed, respectively, on 1, 5 and 21d after photocoagulation to carry on HE (Hematoxylin - Eosin stain) and VEGF - α (vascular endothelial growth factor - α) immumohistochemical staining. RESULTS: There were three rats died, three rats with severe retinal detachment for excessive bleeding,one rat with retinal sunken, and one rat with cataract. FFA and fundus ( fluorescein) photograph showed that the successful BRVO rat model was 73% (22/30). It was found that the near-end photocoagulation vein became coarse, far - end became diminution on 1d and the photocoagulation vein total recanalization was on 3-7d. ERG showed the amplification of b wave (dark -adaptation 3.0 response) decreased to 0.694士0.042 of control eyes and on 5-7d decreased to rock bottom about 0.487士0.064 of control eyes. Then it increased Aii the time to 0.708士0.0465 of control eyes on 21d. OCT and HE staining found that retinal ganglion cells and outer nuclear layer became edema on 1d in vivo and in vitro.It was observed that the thickness of retina on photocoagulation vein (0μ m or 250μ m) decreased from 5d and there were 3-4 layer cells in ONL on 21d. The expression of VEGF-α at injured site were significantly more than control eyes on 1d and there were no significant difference on 5d;But the expression of VEGF-α were slightly less than control eyes on 21d. CONCLUSION: Photochemical method was a feasible method to establish BRVO rat model. The evolution and development of the BRVO model could partly mimic human BRVO phenomenon. At the same time, it should be improved to increase the successful model rate.

Research on targets distinguishing and locating technique via UWB bioradar based on pixel segmentation algorithm / 医疗卫生装备

Objective To explore the feasibility and applicable conditions of one-dimensional distance distinction combining pixel segmentation algorithm in multi-target recognition and identification of multi-channel ultra wide-band bioradar.Methods The signals the radar received were decomposed,reconstructed and filtered,and one-dimensional distance distinction algorithm was applied to achieving multi-target distance discrimination,then multi-target two-dimensional positioning was achieved based on the principle of angle determination applying pixel segmentation algorithm.Finally,a target positioning experiment was executed by collecting 10 volunteers using the method above.Results The experiment indicated that pixel segmentation algorithm gained advantages when used for positioning a single target while disadvantages for multi target.Concluslon It's proved that it's feasible to locate three or less targets with one-dimensional distance distinction as well as two-dimensional locating based on pixel segmentation algorithm.Positioning accuracies are different in case of numbers of targets.

Research on targets distinguishing and locating technique via UWB bioradar based on pixel segmentation algorithm / 医疗卫生装备

Objective To explore the feasibility and applicable conditions of one-dimensional distance distinction combining pixel segmentation algorithm in multi-target recognition and identification of multi-channel ultra wide-band bioradar.Methods The signals the radar received were decomposed,reconstructed and filtered,and one-dimensional distance distinction algorithm was applied to achieving multi-target distance discrimination,then multi-target two-dimensional positioning was achieved based on the principle of angle determination applying pixel segmentation algorithm.Finally,a target positioning experiment was executed by collecting 10 volunteers using the method above.Results The experiment indicated that pixel segmentation algorithm gained advantages when used for positioning a single target while disadvantages for multi target.Concluslon It's proved that it's feasible to locate three or less targets with one-dimensional distance distinction as well as two-dimensional locating based on pixel segmentation algorithm.Positioning accuracies are different in case of numbers of targets.

In-vivo and ex-vivo studies on region-specific remodeling of large elastic arteries due to simulated weightlessness and its prevention by gravity-based countermeasure / 生理学报

The present study was designed to test the hypothesis that a medium-term simulated microgravity can induce region-specific remodeling in large elastic arteries with their innermost smooth muscle (SM) layers being most profoundly affected. The second purpose was to examine whether these changes can be prevented by a simulated intermittent artificial gravity (IAG). The third purpose was to elucidate whether vascular local renin-angiotensin system (L-RAS) plays an important role in the regional vascular remodeling and its prevention by the gravity-based countermeasure. This study consisted of two interconnected series of in-vivo and ex-vivo experiments. In the in-vivo experiments, the tail-suspended, hindlimb unloaded rat model was used to simulate microgravity-induced cardiovascular deconditioning for 28 days (SUS group); and during the simulation period, another group was subjected to daily 1-hour dorso-ventral (-G(x)) gravitation provided by restoring to normal standing posture (S + D group). The activity of vascular L-RAS was evaluated by examining the gene and protein expression of angiotensinogen (Ao) and angiotensin II receptor type 1 (AT1R) in the arterial wall tissue. The results showed that SUS induced an increase in the media thickness of the common carotid artery due to hypertrophy of the four SM layers and a decrease in the total cross-sectional area of the nine SM layers of the abdominal aorta without significant change in its media thickness. And for both arteries, the most prominent changes were in the innermost SM layers. Immunohistochemistry and in situ hybridization revealed that SUS induced an up- and down-regulation of Ao and AT1R expression in the vessel wall of common carotid artery and abdominal aorta, respectively, which was further confirmed by Western blot analysis and real time PCR analysis. Daily 1-hour restoring to normal standing posture over 28 days fully prevented these remodeling and L-RAS changes in the large elastic arteries that might occur due to SUS alone. In the ex-vivo experiments, to elucidate the important role of transmural pressure in vascular regional remodeling and differential regulation of L-RAS activity, we established an organ culture system in which rat common carotid artery, held at in-vivo length, can be perfused and pressurized at varied flow and pressure for 7 days. In arteries perfused at a flow rate of 7.9 mL/min and pressurized at 150 mmHg, but not at 0 or 80 mmHg, for 3 days led to an augmentation of c-fibronectin (c-FN) expression, which was also more markedly expressed in the innermost SM layers, and an increase in Ang II production detected in the perfusion fluid. However, the enhanced c-FN expression and increased Ang II production that might occur due to a sustained high perfusion pressure alone were fully prevented by daily restoration to 0 or 80 mmHg for a short duration. These findings from in-vivo and ex-vivo experiments have provided evidence supporting our hypothesis that redistribution of transmural pressures might be the primary factor that initiates region-specific remodeling of arteries during microgravity and the mechanism of IAG is associated with an intermittent restoration of the transmural pressures to their normal distribution. And they also provide support to the hypothesis that L-RAS plays an important role in vascular adaptation to microgravity and its prevention by the IAG countermeasure.

Short-term simulated weightlessness enhances response of L-type calcium channel to angiotensin II in cerebral vascular smooth muscle cells in rats / 生理学报

Some studies suggest that the calcium channels and rennin-angiotensin system (RAS) play pivotal roles in the region-specific vascular adaptation due to simulated weightlessness. This study was designed to clarify if angiotensin II (Ang II) was involved in the adaptational change of the L-type calcium channel (Ca(L)) in the cerebral arterial vascular smooth muscle cells (VSMCs) under simulated weightlessness. Tail suspension (SUS) for 3 d was used to simulate immediate early cardiovascular changes to weightlessness. Then VSMCs in cerebral basilar artery were enzymatically isolated using papain, and Ca(L) current (barium instead of calcium as current carrier) in VSMCs was measured by whole-cell patch-clamp techniques. The results showed that 3-day simulated weightlessness significantly increased current density of Ca(L). However, I-V relationships of normalized peak current densities and steady-state activation curves of Ca(L) were not affected by simulated weightlessness. Although Ang II significantly increased current densities of Ca(L) in both SUS and control rats, the increase of Ca(L) current density in SUS rats was much more than that in control rats. These results suggest that 3-day simulated weightlessness induces the adaptational change of Ca(L) in cerebral VSMCs including increased response to Ang II, indicating that Ang II may play an important role in the adaptational change of cerebral arteries under microgravity.