A three-dimensional (3D) model of human anterior chamber is reconstructed to explore the effect of different corneal temperatures on the heat transfer in the chamber. Based on the optical coherence tomography imaging of the volunteers with normal anterior chamber, a 3D anterior chamber model was reconstructed by the method of UG parametric design. Numerical simulation of heat transfer and aqueous humor flow in the whole anterior chamber were analyzed by the finite volume methods at different corneal temperatures. The results showed that different corneal temperatures had obvious influence on the temperature distribution and the aqueous flow in the anterior chamber. The temperature distribution is linear and axial symmetrical around the pupillary axis. As the temperature difference increases, the symmetry becomes poorer. Aqueous floated along the warm side and sank along the cool side which forms a vortexing flow. Its velocity increased with the addition of temperature difference. Heat fluxes of cornea, lens andiris were mainly affected by the aqueous velocity. The higher the velocity, the bigger more absolute value of the above-mentioned heat fluxes became. It is practicable to perform the numerical simulation of anterior chamber by the optical coherence tomography imaging. The results are useful for studying the important effect of corneal temperature on the heat transfer and aqueous humor dynamics in the anterior chamber.
The new mechanisms of automaticity controlled by the calcium and membrane clocks in sinoatrial node are helpful to revealing the sinus arrhythmia, but the present calcium dynamic model is only on the single cell level. In the present study, a central and peripheral single cell model was developed, and by exponentially changing the cell membrane capacitance, size, conductance and gap junction from the center to the periphery, a two-dimensional inhomogeneous sinus and atrial model was created on the basis of the anatomical structure. Five-point difference and finite element methods were used to process the internal grids and the borders. Irregular borders were defined by creating segment trial functions. Quantitative experiments suggested the consistency of the central and peripheral action potentials with related reports in amplitude, cycle length, maximum diastolic potential and upstroke velocity. Functions of the calcium and membrane clocks on the leading pacemaker site and upstroke velocity as well as the effects of the atrial premature beat on the sinus automaticity were also in good agreement with those in other studies. The developed model is helpful for deeply studying relative roles of the calcium and membrane clocks in automaticity and the relations with electrical activities in atrium. At the same time it will lay the foundation for building three-dimensional sinus and atrial organic models.
Objective To observe the effects of minocycline to the viability and apoptosis of ratprime;s retinal neuron cells (RNC) under pressure, and to investigate the neuroprotective mechanisms of minocycline against the RNC damage. Methods Establish a model of ratprime;s RNs under pressure cultured in vitro, the protective effect of minocycline is observed by different methods, including observing the morphology of the cells, evaluating the cellsprime; viability by methyl thiazolyl tetrazolium (MTT) colorimetry assay, and detecting the cellular apoptosis with acridine orange/ethidium bromide (AO/EB) double staining by fluorescence microscopy. Immunocytochemistry was used to detect the expression of iNOS and caspase-3 in the cells. Results Obvious morphology changes of RNC were found in cells under pressure compared with the control; the viability of RNC decreased and cellular apoptosis was found in 53.93% cells. The cellular morphology improved in the cells treated by 20 mu;mol/L minocycline, the cellular viability significantly increased, and the cellular apoptosis was found in 17.29% cells. In addition, the expression of iNOS and caspase3 in the treated cells decreased compared with which in the pressured group. Conclusion Minocycline with a certain concentration can effectively inhibit pressureinduced damage and apoptosis of RNC of rats, and the inhibitory effect on expression of iNOS and capases-3 may be the underlying mechanism.
Objetive To observe the incidence of extraocular extension of malignant uveal melanoma, the relationship between the incidence and histopathologic type, the characters of clinical manifestation and iconography, and the factors influencing prognosis. Methods Nine cases of extraocular extension of malignant uveal melanoma within last 20 years were analyzed retrospectively. All cases were diagnosed by histopathological examination and most of them had undergone ultrasound and CT examinations. Results The incidence of extraocular extension of malignant uveal melanoma was 15%. Tumors of 6 patients were flat and 2 nodular in shape, 4 epithelial cell and 1 spindle cell in type. The follow-up results of 5 patients in this series indicated that the prognosis was related to the size of the tumor, the degree of extraocular extension, and histopathologic type. Conclusion Extraocular extension of malignant uveal melanoma might happen in early case and the occurrence is usually related to the histopathologic type of the tumor. Iconographic examination is very helpful for diagnosis in extraocular extension of this tfumor. (Chin J Ocul Fundus Dis,1999,15:30-32)
The "bnma" package is a Bayesian network meta-analysis software package developed based on the R programming language. The network meta-analysis was performed utilizing JAGS software, which yielded relevant results and visual graphs. Moreover, this software package provides support for various data structures and types, while also providing the advantages of flexible utilization, user-friendly operation, and deliver of rich and accurate outcomes. In this paper, using a network meta-analysis example of different therapies for androgenetic alopecia, the operational process of conducting network meta-analysis using the "bnma" package is briefly introduced.
ObjectiveTo assess the use of 18-Fluorine-labelled 2-deoxy-2-fluoro-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) in the diagnosis of uveal melanoma. MethodsTwenty-three patients with uveal melanoma confirmed by histopathologic examination or imaging examination were enrolled. There were 16 male, 7 female, and the mean age was (49.8±12.3) years. All the lesions were unilateral, with 11 cases in OD, 12 cases in OS. Diagnosis was confirmed by histopathological examination of enucleated eyeballs in 15 cases, by ophthalmoscope, fundus fluorescein angiography, ocular B-mode ultrasound and magnetic resonance imaging and other imaging technology in 8 cases. 15 patients diagnosed by histopathologic examination of enucleated eyeballs were divided into three types including mixed (7 patients), spindle cell (6 patients) and epithelioid cell (2 patients) types. The mixed cell type and epithelioid cell type are considered as high-risk; spindle cell type is low-risk. All the patients were evaluated by whole body PET/CT. The location, size, shape, boundary of the lesions, and the relationship with adjacent structures were observed in CT images. 18F-FDG uptake was quantitative expression by standardized uptake value (SUV) in PET image; positive diagnosis should be made when the maximum standardized uptake value (SUVmax) was not less than 2.5. The correlation between SUVmax and maximum diameter of tumor base, tumor height was analyzed by Spearman rank correlation test. The detection rate of high-risk and low-risk patients between 18F-FDG PET and CT methods was comparative analyzed. ResultsAll the CT images showed abnormal high density ocular lesions. The shape of the lesions included 8 patients of semi sphere-like, 7 patients of flat-like, 4 patients of mushroom-like, 3 patients of round-like and 1 patient of diffuse lesions. The tumors were located in the posterior pole (9 patients), temporal equator (5 patients), nasal equator (4 patients), superior equator (1 patient), temporal ciliary body (1 patient), inferior ciliary body (1 patient), temporal iris (1 patient), and nasal iris and ciliary body (1 patient). SUVmax≥2.5 were found in 9 patients (39.13%), the largest basal diameter and height were (17.53±3.48), (11.37±3.85) mm respectively. SUVmax < 2.5 were found in 14 patients (60.87%), the largest basal diameter and height were (10.66±3.25), (5.33±2.23) mm respectively. The former's largest basal diameter and height were greater than the latter's and the difference was statistically significant (t=4.815, 4.786; P < 0.01). SUVmax was positively correlated with the largest basal diameter and height respectively (r=0.881, 0.809; P < 0.01). 15 patients (39.13%) were diagnosed by histopathological diagnosis after enucleation, of which SUVmax≥2.5 were found in 8 patients which included 6 patients of mixed type, 1 patient of epithelioid cell type, and 1 patient of spindle cell type. The detection rate of high-risk type (77.78%, 7/9) was higher than that of low-risk type (16.67%, 1/6), the difference was statistically significant (χ2=5.402, P < 0.05). Conclusions18F-FDG PET-CT examination can show large uveal melanoma tumor from cell metabolism, and may help to evaluate the prognosis of the preoperative patients. But, for small tumor, it has little value. We don't recommend 18F-FDG PET-CT is used as a routine examination for uveal melanoma.