900MHz微波电磁辐射对原代培养的大鼠脑皮质神经元能量代谢的影响

目的　研究 90 0MHz微波电磁辐射对原代培养的大鼠脑皮质神经元能量代谢的影响。方法　将大鼠脑皮质神经元暴露于 90 0MHz的连续性微波电磁辐射 (SAR =3 2 2mW g、PD =9mW cm2 ) ,每天暴露 2h ,连续 4d或 5d ,及一次性 1 2h暴露 ,以细胞色素氧化酶为观察指标 ,研究微波对神经元能量代谢的影响。结果　微波电磁辐射可使神经元细胞色素氧化酶活性降低。结论　神经元细胞色素氧化酶活性的改变并非“致热效应”所致 ;微波电磁辐射对神经元细胞色素氧化酶活性影响有蓄积毒性作用 ,其影响在一定程度上是可恢复的 ,并且与神经元接受微波辐射时细胞培养年龄关系不密切。     

Microwave coagulation therapy and drug injection to treat splenic injury

Background

The present study compares the efficacy of 915- and 2450-MHz contrast-enhanced ultrasound (CEUS)–guided percutaneous microwave coagulation with that of CEUS-guided thrombin injection for the treatment of trauma-induced spleen hemorrhage.

Materials and methods

In a canine splenic artery hemorrhage model with two levels of arterial diameter (A, <1 mm and B, between 1 and 2 mm), hemostatic therapy was performed using 915- and 2450-MHz microwaves and drug injection. Therapy efficacy was measured by comparing bleeding rate, hemostatic time, bleeding index, bleeding volume, and pathology.

Results

The most efficient technique was CEUS-guided 915-MHz percutaneous microwave coagulation therapy in terms of action time and total blood loss. The success rate of the 915-MHz microwave group was higher than that of the 2450-MHz microwave and the drug injection groups (except A level, P < 0.05). Hemostatic time, bleeding index, and bleeding volume were significantly less in the 915-MHz microwave group than those in the 2450-MHz microwave and drug injection groups (P < 0.05). Obvious degeneration and necrosis of parenchyma and large intravascular thrombosis were observed in the cavity of larger vessels in the 915-MHz microwave group, but pathologic changes of light injury could be seen in the other groups.

Conclusions

The present study provides evidence that microwave coagulation therapy is more efficient than thrombin injection for the treatment of splenic hemorrhage. Furthermore, treatment with 915-MHz microwaves stops bleeding more rapidly and generates a wider cauterization zone than does treatment with 2450-MHz microwaves.     

Transurethral microwave therapy in 200 patients with a minimum followup of 2 years: urodynamic and clinical results

PURPOSE: We investigated the long-term efficacy of the second generation Targis thermotherapy device (Urologix, Inc., Minneapolis, Minnesota) for decreasing outflow obstruction caused by benign prostatic hyperplasia. MATERIALS AND METHODS: At a minimum followup of 24 months 200 patients with bladder outlet obstruction documented on urodynamics and cystoscopy document with preserved detrusor function underwent transurethral microwave therapy while under local anesthesia. In 45% of cases the general American Society of Anesthesiologists health score was 3 or greater. RESULTS: After a median observation time of 42 months (range 2 to 72) 43 patients (22%) who required additional treatment (repeat thermotherapy, transurethral prostate resection or permanent cystostomy) were excluded from further analysis, as were 15 (7.5%) who died of causes unrelated to treatment during followup and 13 (6.5%) who were lost to followup or refused followup investigations. In the 162 patients evaluated 6 months after treatment the median International Prostate Symptom Score decreased from 23 points (range 10 to 34) before treatment to 3 (range 0 to 21) and remained stable at 12 and 24 months. Median maximum flow increased from 6 ml. per second (range 1 to 15) before treatment to 14.5 (range 4 to 50) 6 months after treatment and remained stable at 12 and 24 months. Median post-void residual urine volume decreased from 170 ml. (range 35 to 720) before treatment to 17 (range 0 to 327) after 6 months and then remained unchanged. Urodynamic evaluation in the 162 patients after 6 months showed a decrease from pretreatment median detrusor opening pressure of 87.5 to 53 cm. water. Median detrusor pressure at maximum flow decreased from 86 to 58 cm. water 6 (p <0.0001). At the 24-month followup 59 of the 129 evaluable patients agreed to undergo repeat urodynamic evaluation. Pressure flow analysis in these 59 cases revealed a decrease in median minimal urethral opening pressure from 70 to 40 cm. water at 6 months and to 38 cm. water at 24 months (p <0.0001). Median detrusor pressure at maximum flow decreased significantly from the pretreatment value of 86 to 55 cm. water at 6 months and 58 cm. water at 24 months (p <0.0001). CONCLUSIONS: In patients with a good initial response to treatment, which is achieved in approximately 80%, transurethral microwave therapy provides excellent long-term subjective and objective results. Improved urinary flow, decreased post-void residual urine volume and urodynamic parameters remain stable at 2 years. Transurethral microwave therapy with second generation microwave equipment did not compromise any conventional treatment needed in the 22% of patients who were nonresponders at 6 months.     

Variability in catheter microwave sterilization techniques in a single clinic population

PURPOSE: We designed a survey to assess the microwave sterilization technique practiced by patients at our clinic who perform clean intermittent catheterization. MATERIALS AND METHODS: A 23-question survey addressing urinary catheter use and home sterilization techniques was mailed to 129 patients. A followup survey was mailed to 47 respondents who reported using a microwave oven to sterilize the catheters to assess the microwave technique further. RESULTS: Of the 129 initial surveys 84 (64%) were returned, while 40 (85%) of the 47 followup questionnaires on microwave sterilization were returned. All patients surveyed have used clean intermittent catheterization for at least 1 year and 75% have used it more than 5 years. Of the respondents 80% perform clean intermittent catheterization 4 to 5 times daily, although sterilization frequency varies from daily to less than once weekly. Of the respondents 71% reported no difficulty with microwave sterilization, although 31 (63%) reported a history of catheter melting during microwaving. Of the respondents 35% reported using a rotation table, all used a heat sink containing 1/2 to 4 cups of water, 39% used 500 to 1,000 W., 37% used greater than 1,000 W., 73% set the microwave for 6 minutes, others set it for 3 to 30 minutes and 98% used a power setting described as high, full, 10 or 100%. CONCLUSIONS: Significant variation exists in the cleaning and sterilizing techniques used by our patients, although they were given uniform written and verbal instructions. It is unclear from the data in the literature how this variation affects sterilization.     

Magnetic resonance imaging appearances of the uterus following microwave endometrial ablation

AIM: Microwave endometrial ablation (MEA) is a treatment for dysfunctional uterine bleeding. It is a second generation ablative technique which is as effective as hysteroscopic methods but quicker and easier to perform. Our aim is to describe the Magnetic Resonance Imaging (MRI) appearances of the uterus following this procedure. METHODS: 15 women underwent MRI immediately before MEA, and again at one day and 4 months after treatment. T1 and T2 sequences were performed at 1.0T using a body coil. Images were assessed by 2 independent observers for quantitative and qualitative changes. Clinical questionnaires were completed before treatment and at 4 months. RESULTS: On images obtained one day post-ablation, 14 patients had a low signal intensity band subjacent to the treated area of the endometrial cavity on T2 images. Imaging at 4 months showed significant amounts of endometrial tissue in 11 patients, including 3 of the 6 patients who were amenorrhoeic. There were no changes in the appearances of myometrium or uterine dimensions and there were no haematometra. CONCLUSIONS: The detection of residual endometrium by MRI means that unopposed oestrogen hormone replacement therapy should be avoided after MEA, even in women who have amenorrhoea. Thepost-operative sub-endometrial low signal intensity zone corresponds to the region of tissue necrosis detected on vital staining of the treated uterus in in vivotesting. Depth of tissue destruction is a surrogate marker for clinical effectiveness. MRI may have a role in early assessment of patients participating in clinical research who are undergoing a modified MEA technique while retaining their uterus.     

Interstitial microwave thermal therapy for prostate cancer: method of treatment and results of a phase I/II trial

PURPOSE: Interstitial microwave thermal therapy is experimental treatment for prostate cancer with the goal of curing disease, while causing fewer complications than standard treatment options. We present a method for delivering interstitial microwave thermal therapy using microwave radiating helical antennae inserted percutaneously under transrectal ultrasound guidance. We report the results of a trial of this method in 25 patients in whom primary external beam radiation therapy had previously failed. This patient group currently has limited curative options that are associated with a high complication rate. However, these recurrent tumors often remain localized to the prostate, and so they may be amenable to localized therapy. MATERIALS AND METHODS: Patients with proved prostatic adenocarcinoma were candidates for treatment when prostate specific antigen (PSA) was 15 ng./ml. or less and prostate volume was 50 cc. or less. Followup included PSA measurement, digital rectal examination, urinalysis, and documentation of adverse events at 4, 8, 12 and 24 weeks. Sextant biopsy was performed at week 24. The procedure involved the insertion of 5 antennae percutaneously through a modified brachytherapy template. The antenna arrangement was determined based on computer simulated predictions of temperature throughout the prostate. The prostate was dissected away from the rectum by an injection of sterile saline to provide a thermal barrier that protected the rectum from thermal damage. Temperatures were monitored using interstitial mapping thermistor probes that were also inserted through the template. A minimum peripheral target temperature of 55C but less than 70C was maintained for 15 to 20 minutes, while the urethra, rectum and hydrodissection space remained below 42C. The urethra and rectum were actively cooled in addition to hydrodissection. RESULTS: Peripheral target temperatures of 55C were achieved. The urethra and rectum remained at a safe temperature. The procedure, including setup and treatment, required approximately 2.5 hours of operating room time. At 24 weeks the PSA nadir was 0.5 ng./ml. or less in 52% of patients and 0.51 to 4 ng./ml. was achieved in an additional 40%. The negative biopsy rate at 24 weeks was 64%, assuming that 3 patients lost to followup would have had positive results. No major complications were observed and in most cases minor complications resolved within 3 months. CONCLUSIONS: Interstitial microwave thermal therapy for prostate cancer was developed to heat the prostate safely to a cytotoxic temperature. Experience with 25 patients in whom external beam radiation therapy for prostate cancer had failed indicates that the treatment is safe. Although our series indicates that this therapy may be effective, further studies and longer followup are required in larger patient groups to confirm the potential role of this therapy as an option for recurrent and primary prostate cancer.     

Reversible microwave effects on the blood-brain barrier

Low level microwave exposure of Chinese hamster resulted in reversible permeability of the blood-brain barrier (BBB) to horseradish peroxidase (HRP). Lesions were grossly visible in random areas of the brain immediately following exposure, but were not as common following a 1 h recovery period and were absent after a 2 h recovery period. The apparent route of increased permeability was via endothelial vesicular transport, since reaction product was not seen passing through the endothelial tight junctions. In addition, endothelial flooding of HRP, platelet aggregation and perivascular edema were observed only in experimental animals. Possible mechanisms for the enhanced vesicular transport are discussed.     

900MHz微波电磁辐射对大鼠大脑皮质神经元神经递质受体γ-氨基丁酸蛋白表达的影响

目的研究900MHz微波电磁辐射对原代培养大鼠大脑皮质神经元神经递质γ-氨基丁酸(GABA)受体表达的影响。方法将大鼠大脑皮质神经元暴露于900MHz的连续性微波电磁辐射(SAR=1.15~3.22W/kg),进行每天2h、连续6d暴露及一次性12h暴露,以GABA受体蛋白表达为观察指标,研究微波对神经元的兴奋性影响。结果微波电磁辐射影响神经元GABA受体表达。结论微波电磁辐射对神经元兴奋性影响可能存在“窗口效应”。     

微波辅助治疗小儿支气管肺炎的效果

目的观察微波辅助治疗小儿支气管肺炎的效果。方法223例小儿支气管肺炎病儿随机分为两组,微波辅助治疗组（n=102）在对照组（n=121）传统治疗的基础上加用微波治疗机照射,评价两组间疗效差异。结果微波辅助治疗组小儿支气管肺炎疗效与对照组比较,差异有极显著意义（uc=3.72,P〈0.01）。结论微波辅助治疗小儿支气管肺炎疗效肯定、安全,值得推广使用。