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find Keyword "region" 102 results
  • Retrospective clinical study on the comprehensive treatment of retinoblastoma

    ObjectiveTo observe the curative effect, survival rate, enucleation rate and pathological characteristics of retinoblastoma (RB) in children.MethodsRetrospective clinical study. From March 1999 to December 2018, a total of 313 patients (445 eyes) with RB diagnosed in Ophthalmology Department of Peking University People’s Hospital were enrolled in the study. Among them, 175 were male (55.9%), 138 were female (44.1%); 181 were monocular and 132 were binocular. The international standard of intraocular RB staging (IIRC) was 6, 13, 6, 52, 227 and 9 patients of A, B, C, D, E and extraocular stages respectively. Among the 313 patients, 245 patients were confirmed to the survivance, of which 22 cases (9.0%, 22/245) died. Among 445 eyes, 330 eyes definitely whether or not were enucleated; 184 eyes had definite IIRC stage, eye examination results, definite treatment plan and times before enucleation and definite pathological tumor node metastasis stage after operation. The basic information, demographic characteristics, clinical information, enucleation and treatment plan, pathological and immunohistochemical results were recorded. Binary logistic regression was used to analyze the risk factors of high risk pathological features (HRF) and prognosis in patients with RB.ResultsFrom 1999 to 2018, the survival rate of 245 patients was increased from 82.6% to 96.3% year by year; the enucleation rate of 330 eyes with final enucleation was reduced from 68.8% to 58.3% year by year. The rate of enucleation in stage D and stage E decreased from 83.3% and 100% before 2005 to 37.5% and 85.4% after 2014, respectively. Monocular disease (β=-1.551, P=0.005), stage D, stage E and extraocular stage in IIRC stage (P<0.005) were the independent risk factors of RB enucleation, while the protective factors were Interventional chemotherapy of ophthalmic artery (IAC) (β=-0.877, P<0.001). HRF was found in 51 eyes (27.7%). Age of onset (β=0.019, P=0.016) and glaucoma (β=0.816, P=0.050) were independent risk factors for HRF in RB pathology, while IAC treatment was the protective factor for enucleation (β=21.432, P<0.001).ConclusionsAfter comprehensive treatment, the general trend of RB enucleation rate is gradually decreasing. IAC treatment can reduce the enucleation rate of stage D and E. The older age of onset and glaucoma stage are the independent risk factors of HRF, and IAC can reduce the risk factors of HRF.

    Release date:2020-07-20 08:34 Export PDF Favorites Scan
  • Numerical simulation of the focal region modulation to realize uniform temperature distribution during high-intensity focused ultrasound brain tumor therapy

    The temperature during the brain tumor therapy using high-intensity focused ultrasound (HIFU) should be controlled strictly. This research aimed at realizing uniform temperature distribution in the focal region by adjusting driving signals of phased array transducer. The three-dimensional simulation model imitating craniotomy HIFU brain tumor treatment was established based on an 82-element transducer and the computed tomography (CT) data of a volunteer's head was used to calculate and modulate the temperature distributions using the finite difference in time domain (FDTD) method. Two signals which focus at two preset targets with a certain distance were superimposed to emit each transducer element. Then the temperature distribution was modulated by changing the triggering time delay and amplitudes of the two signals. The results showed that when the distance between the two targets was within a certain range, a focal region with uniform temperature distribution could be created. And also the volume of focal region formed by one irradiation could be adjusted. The simulation results would provide theoretical method and reference for HIFU applying in clinical brain tumor treatment safely and effectively.

    Release date:2019-02-18 02:31 Export PDF Favorites Scan
  • APPLICATION OF FASCIOCUTANEOUS FLAP IN REPAIRING Ⅲ° BURN WOUND IN FACIO-CERVICAL REGION

    OBJECTIVE: To evaluate the clinical efficacy of fasciocutaneous flap in the repair of the III degree burn wound in the facio-cervical region. METHODS: From January 1997 to October 2001, 11 cases of III degree burn wounds in the facio-cervical region were repaired with the cervical-thoracic fasciocutaneous flap ranging from 18 cm x 8 cm to 13 cm x 5 cm. Donor sites were covered with "Z" plasty or skin grafting. RESULTS: Except for partial necrosis of distal end of the flap in 1 case, the flaps in the other 10 cases all survived and presented satisfactory appearance and function during the following up. CONCLUSION: The fasciocutaneous flap in the cervical-thoracic region may provide a large area of flap, and can be easily transferred. It’s an ideal flap for the repair of skin defect in the facio-cervical region, especially for the repair of the wounds with infection or exposure of vessel, nerve and tendon.

    Release date:2016-09-01 09:35 Export PDF Favorites Scan
  • TRANSPLANTATION OF FREE SCAPULAR FLAP TO REPAIRING INJURY OF FACIOCERVICAL REGION

    OBJECTIVE: To sum up transplantation of free scapular flap to repairing injury of faciocervical region, 103 cases in past 16 years were reviewed. METHODS: The scapular flap contained the ascending, descending, and transverse branches of the circumflex scapular artery. The range of the flap was as following: across the scapular spine to the acromion in upper edge, to the level of anterior iliac spine in lower edge, to the bilateral middle axillary line in both sides. RESULTS: The clinical result was good. Fifty eight cases were followed up for 3 months to 10 years, the function of the faciocervical region was recovered with satisfied contour. In part of the patients, a second-stage operation was performed to make the flap thinner. CONCLUSION: The maximal range of the flap can be 45 cm x 16 cm. For its sufficient blood supply, it should be of no influence on survival of the flap if the window is open in suitable site. Because of its large range of donating region and sufficient blood supply, it is fit for children.

    Release date:2016-09-01 10:27 Export PDF Favorites Scan
  • Advances in the application of hemofiltration replacement fluid of sodium citrate in continuous renal replacement therapy

    Safe and effective anticoagulation is crucial in continuous renal replacement therapy. Citrate anticoagulation is widely used for its advantages of low bleeding risk, high anticoagulation efficacy, and extended filter lifespan. However, the commonly used citrate-containing anticoagulants in clinical practice, such as 4% trisodium citrate, may impose excessive citrate and sodium loads, increasing the risk of metabolic alkalosis and hypernatremia, especially in patients whose replacement fluid electrolytes are not appropriately adjusted. In recent years, the clinical use of low-concentration sodium citrate-based replacement fluids has reduced the incidence of metabolic disturbances. When combined with calcium-free, phosphate-containing, and low-buffer bicarbonate solutions, this approach offers additional benefits such as simplified workflow, reduced circuit complexity, and improved electrolyte stability, achieving both effective anticoagulation and electrolyte homeostasis.

    Release date:2025-07-29 05:02 Export PDF Favorites Scan
  • The status and progress of intravitreal chemotherapy for resistant or recurrent retinoblastoma

    Nowadays, one of the most challenging aspects of retinoblastoma (RB) therapy is how to control the resistant or recurrent viable vitreous seeds, for which intravenous chemotherapy appears to be ineffective. Recently, intravitreal chemotherapy offers another option to control advanced stage and vitreous seeds of RB, and may be a promising new approach to RB therapy. However, intravitreal injection for RB patients raises considerable controversy due to concerns of possible extraocular extension along the injection route, and should not replace the primary standard of care for bilateral RB or group E eyes of RB. Close follow-up and further studies are needed to determine appropriate indications, to determine the effective drugs and concentrations, to optimize RB therapy protocols and to investigate the relationship between long-term efficacy and toxicities.

    Release date:2016-10-02 04:55 Export PDF Favorites Scan
  • Intravitreal methotrexate chemotherapy in the treatment of 14 patients with priamary vitreoretinal lymphoma

    ObjectiveTo evaluate the safety and efficacy of the intravitreal methotrexate treatment in patients with primary vitreoretinal lymphoma (PVRL). MethodsRetrospective non-comparative interventional case series. Fourteen patients (26 eyes) with biopsy-proven PVRL were included in the study. All patients received examination of Snellen chart visual acuity, fundus color photography and optical coherence tomography (OCT). Among the 24 eyes with recordable visual acuity, 17 eyes has initial visual acuity≥0.1 (0.45±0.20) and 7 eyes with initial visual acuity ranged from light perception to hand movement. The vitreous opacities and (or) subretinal yellowish-white lesions and retinal pigment epitheliumuplift were observed in all eyes. All eyes were treated with intravitreal methotrexate (4000 μg/ml, 0.1 ml) injections according to a induction-consolidation-maintenance regimen. For 26 treated eyes, each received an average of (11.5±6.3) injections. Twenty eyes had finished theintraocular chemotherapy, while 6 eyes had not. Eight of 20 eyes were clinically confirmed free of tumor cells by diagnostic vitrectomy, 12 eyes were still with tumor cell involvement.The follow-up was ranged from 2 to 48 months, the mean time was 18 months. The examination of BCVA, fundus color photography and OCT were performed. No tumor cell was defined as clinical remission. Visual acuity was scored as improved or declined obviously (improved or declined 2 lines) or mild improved or declined (changed within 2 lines). ResultsTwenty eyes achieved clinical remission after (3.5±3.6) injections, 12 eyes of 20 eyes with tumor cell involvement before chemotherapy achieved clinical remission after (5.8±3.0) injections. The mean visual acuity of seventeen eyes with initial visual acuity 0.1 in induction phase and at the end of treatment were 0.36±0.23 and 0.56±0.20, respectively. Compared with before treatment, the visual acuity was mild declined in induction phase (t=1.541, P>0.05), but mild improved at the end of treatment (t=2.639, P<0.05). The visual acuity at the end of treatment in 7 eyes with initial visual acuity<0.1 was ranged from no light perception to 0.1. Of 14 patients, 2 patients have been fatal because of brain lesions progression at 42 and 48 months after diagnosis of primary central nervous system lymphoma. No ocular recurrence was noted during the follow-up in 20 eyes who finished intraocular chemotherapy. ConclusionsPVRL patients can achieve clinical remission after (3.5±3.6) injections by intravitreal chemotherapy of methotrexate, and the visual acuity improved mildly. No ocular recurrence was found during follow-up.

    Release date:2016-10-02 04:55 Export PDF Favorites Scan
  • Implementation of V1 Area Contour Integration Mechanism and Attention Selection Based on Excitation-Inhibition Intersecting Cortical Model

    This paper aims to utilize the intersecting cortical model (ICM), which imitates the biological neural cells sync pulse, to preliminary research about the contour integration mechanism and the selection of attention. The idea of "Excitement-Inhibition" oscillation is introduced into the ICM, and meanwhile, the target contour chain code is used as the high-level feedback to control the input. Thus, we propose the Excitation-Inhibition-ICM which contains both the BUTTON-UP and the TOP-DOWN mechanism. The experimental results showed that the proposed model could effectively suppress noise to make the smooth edge synchronization issue, thus completing the process of BOTTOM-UP. The introduction of the target contour chain code can obtain consistent target outline with the input target chain code, but other targets cannot form a closed contour since they do not match with the input target chain code, so as to realize the TOP-DOWN mechanism. The results proved that our proposed model could imitate the contour integration mechanism and the selection of attention of the visual cortex V1.

    Release date:2016-10-24 01:24 Export PDF Favorites Scan
  • REPAIRING OF INGUINAL SCAR CONTRACTURE DEFORMITY IN CHILDREN WITH TRANSPOSITIONAL FASCIOCUTANEOUS FLAP

    OBJECTIVE: To investigate the repairing method of inguinal scar contracture deformity in children with transpositional fasciocutaneous flap of anterior-medial side of thigh. METHODS: From August 1989 to August 1999, 33 cases with inguinal scar contracture deformity were adopted in this study. Among them, there were 26 males and 7 females, aged from 3 to 11 years old. The transpositional fasciocutaneous flap consisted of a huge tongue-shape flap with a pedicled triangular flap between the edge of skin defect and the above tongue-shape flap. The maximal size of the transpositional fasciocutaneous flap was 18 cm x 10 cm and the minimal size was 13 cm x 8 cm, the transpositional angle was 60 degrees to 80 degrees. During operation, the tongue-shape flap was used to repair the inguinal region and the triangular flap was used to repair the donor site in one stage. RESULTS: All the flaps survived. The function and appearance of perineum were satisfactory. CONCLUSION: The transpositional fasciocutaneous flap is suitable for repairing the inguinal scar contracture deformity in children, and skin graft is unnecessary.

    Release date:2016-09-01 10:28 Export PDF Favorites Scan
  • Design and application of neural electrical stimulation system with time-varying parameters

    Currently, commercial devices for electrical neural stimulations can only provide fixed stimulation paradigms with preset constant parameters, while the development of new stimulation paradigms with time-varying parameters has emerged as one of the important research directions for expanding clinical applications. To facilitate the performance of electrical stimulation paradigms with time-varying parameters in animal experiments, the present study developed a well-integrated stimulation system to output various pulse sequences by designing a LabVIEW software to control a general data acquisition card and an electrical stimulus isolator. The system was able to generate pulse sequences with inter-pulse-intervals (IPI) randomly varying in real time with specific distributions such as uniform distribution, normal distribution, gamma distribution and Poisson distribution. It was also able to generate pulse sequences with arbitrary time-varying IPIs. In addition, the pulse parameters, including pulse amplitude, pulse width, interphase delay of biphasic pulse and duration of pulse sequence, were adjustable. The results of performance tests of the stimulation system showed that the errors of the parameters of pulse sequences output by the system were all less than 1%. By utilizing the stimulation system, pulse sequences with IPI randomly varying in the range of 5~10 ms were generated and applied in rat hippocampal regions for animal experiments. The experimental results showed that, even with a same mean pulse frequency of ~130 Hz, for neuronal populations, the excitatory effect of stimulations with randomly varying IPIs was significantly greater than the effect of stimulations with fixed IPIs. In conclusion, the stimulation system designed here may provide a useful tool for the researches and the development of new paradigms of neural electrical stimulations.

    Release date:2022-02-21 01:13 Export PDF Favorites Scan
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