Glucose microsensor based on electrochemical deposition of iridium and glucose oxidase onto carbon fiber electrodes1

Miniaturized glucose biosensors, prepared by electrochemical deposition of iridium and glucose oxidase (GOx), are characterized. The iridium network offers good retention of GOx and efficient preferential electrocatalytic detection of the liberated hydrogen peroxide at potentials lower than those of common interfering substances (the ascorbic acid signal actually shifts to a higher potential). The remarkable selectivity thus achieved towards the detection of glucose is coupled to a very fast response. Unlike analogous preparations of noble metal carbon fiber biosensors, a two-step electrodeposition process is required for the fabrication of Ir/GOx microelectrodes. The dependence of the biosensor response upon electrodeposition parameters, such as amounts of GOx and iridium or plating time is examined and optimized. Scanning electron microscopy is used to characterized the growth patterns of the iridium and Ir/GOx layers. The high selectivity associated with electrodeposited iridium matrices makes them very attractive for localizing other hydrogen-peroxide-liberating oxidases.     

Malignant obstructive jaundice: treatment with external-beam and intracavitary radiotherapy

Eleven patients with obstructive jaundice from unresectable cholangiocarcinoma, metastatic porta hepatis adenopathy, or direct compression from a pancreatic malignancy were treated at the Stanford University Medical Center from 1978-1983 with an external drainage procedure followed by high-dose external-beam radiotherapy and by an intracavitary boost to the site of obstruction with Iridium192 (Ir192). A median dose of 5000 cGy was delivered with 4-6 Mv photons to the tumor bed and regional lymphatics in 9 patients, 1 patient received 2100 cGy to the liver in accelerated fractions because of extensive intrahepatic disease, and 1 patient received 7000 "equivalent" cGy to his pancreatic tumor bed and regional lymphatics with neon heavy particles. An Ir192 wire source later delivered a 3100-10,647 cGy boost to the site of biliary obstruction in each patient, for a mean combined dose of 10,202 cGy to a point 5 mm from the line source. Few acute complications were noted, but 3/11 patients (27%) subsequently developed upper gastrointestinal bleeding from duodenitis or frank duodenal ulceration 4 weeks, 4 months, and 7.5 months following treatment. Eight patients died--5 with local recurrence +/- distant metastasis, 2 with sepsis, and 1 with widespread systemic metastasis. Autopsies revealed no evidence of biliary tree obstruction in 3/3 patients. Mean survival time from initial laparotomy and bypass was 16.1 months, and from radiotherapy completion was 8.3 months. Evolution of radiation treatment techniques for biliary obstruction in the literature is reviewed. High-dose external-beam therapy followed by high-dose Ir192 intracavitary boost is well tolerated and provides significant palliation. Survival of these aggressively managed patients approaches that of patients with primarily resectable tumors.     

Epidermoid carcinoma of the anal canal

During the past ten years, substantial progress has been made in the knowledge of the natural history of epidermoid carcinoma of the anal canal and of the response of the disease to radiotherapy alone or combined with chemotherapy. At the present time, the main problem in the management of this tumor concerns identification of the best modalities to achieve local control and preservation of anal function. From a series of 276 cases, followed for more than three years, the necessity for a careful pretreatment evaluation was stressed. This included a systematic search for pelvic metastatic lymph nodes by palpation and CT scan. All patients were treated initially by irradiation except those who underwent groin dissection for inguinal node metastasis or colostomy for complete anal obstruction. Three groups of patients have been identified: 1) unresectable or disseminated tumors (33 cases), 2) resectable tumors but not suitable for sphincter conservation (21 cases) treated by radiochemotherapy and delayed surgery, and 3) resectable tumors suitable for sphincter conservation (222 cases) which were treated by a split-course regimen combining a short course of carefully planned external beam irradiation (19 days) followed by an iridium 192 implant after a two-month rest. In this group, which represents 80 percent of the whole series, 80 percent of patients have had their cancer controlled and 90 percent of controlled patients have retained normal anal function. The use of chemotherapy during the first days of irradiation is advisable in all cases to reinforce the efficacy of treatment and increase the chance of anal preservation. Results of the split-course regimen, combining external beam and interstitial irradiation, demonstrate a clear superiority over external beam irradiation alone, especially for large infiltrating tumors, which represent the majority of cases.     

192Ir核素脑瘤间质内照射的动物实验与病理学观察研究

目的观察用１９２Ｉｒ后装机对脑瘤行间质内照射的生物学反应与疗效。材料与方法选用Ｇ４２２皮下荷瘤小鼠模型作照射后肿瘤生长抑制试验及Ｃ６胶质母细胞瘤脑内荷瘤模型作照射后小鼠存活期延长试验，并进行病理学观察。各设２．５Ｇｙ，１０Ｇｙ及对照３个组进行。结果照射后１４天Ｇ４２２皮下肿瘤体积：对照组，２．５Ｇｙ组和１０Ｇｙ组分别为８．３４±１．９８ｃｍ３，５．７３±３．９３ｃｍ３和１．００±１．９ｃｍ３，３组间有显著差异。Ｃ６脑内荷瘤照射后其存活期明显延长，病理学证明照射后瘤组织发生各时相的凋亡与坏死。结论用１９２Ｉｒ行脑胶质瘤间质内照射是治疗脑深部肿瘤的一种可供选择的有效方法     

Direct imaging of biological sulfur dioxide derivatives in vivo using a two-photon phosphorescent probe

Sulfur dioxide (SO₂) and its derivatives sulfite and bisulfite play important roles in biological systems. However, in vivo detection of sulfite/bisulfite remains challenging. In this study, we developed a dinuclear Ir(III) complex (Ir4) as a two-photon phosphorescent probe for sulfite and bisulfite. Ir4 selectively and rapidly responded, with high sensitivity, to sulfite/bisulfite over other bio-related ions and molecules. One-photon and two-photon microscopy images revealed that Ir4 preferentially targeted mitochondria and was capable of imaging biological sulfite/bisulfite levels in vitro and in vivo. In situ sulfite generation in Caenorhabditis elegans was visualized by two-photon excitation real-time imaging. Finally, Ir4 was employed to monitor sulfite distribution in rat brain and other tissues. This study is the first report of the direct visualization of SO₂ derivatives in vivo. These results provide new insights into the biological importance of SO₂.     

两种设计不同的涂层支架的生物相容性研究

目的　评估两种不同结构设计的国产铂 -铱合金明胶蛋白涂层支架置入兔颈动脉后长期的生物相容性。方法　铂 -铱合金支架由 90 %铂和 10 %铱合金制成 ,一代支架为金属丝直径 0 13mm单丝缠绕的螺旋形结构 ,二代支架为金属丝直径为 0 175mm单丝缠绕的“之”字形结构。将两代支架浸入 10 %明胶溶液中经干燥后制成明胶蛋白涂层支架。将支架直视下置入 3 2只正常兔右颈动脉 ,术后 7、14、3 0、90d进行病理形态分析及电镜观察。　结果　 3 2只兔均成功置入支架 ,组织病理学检查显示 :术后 7d一代和二代支架组各有一例不完全性血栓形成。所有支架置入血管段均有不同程度新生内膜增生 ,偶见炎性细胞浸润。随观察时间延长 ,两组平均新生内膜厚度与新生内膜面积呈持续增加趋势 ,且二代明胶蛋白涂层支架组显著小于一代明胶蛋白涂层支架组 (P均 <0 0 0 0 1)。扫描电镜显示 :7d时二代涂层支架表面附着少量单层红细胞 ,几乎完全内皮化 ;14d时透射电镜观察显示血管平滑肌细胞呈典型的合成型改变。结论　不同金属丝直径、不同结构设计的两代国产铂 -铱合金明胶蛋白涂层支架置入兔颈动脉后均具有良好的生物相容性 ,且二代支架引起的新生内膜增殖反应较轻     

26. Intraluminale Bestrahlung mit Iridium 192 —ein neuer Weg zur Behandlung inoperabler Oesophaguscarcinome?

Zusammenfassung Beim inoperablen Oesophaguscarcinom wurde als neues Alternativverfahren gegenüber der Palliativresektion die intraluminale hochdosierte Afterloadingtherapie mit Iridium 192 angewandt. Voraussetzung für dieses Verfahren, das im letzten Jahr bei 19 Patienten eingesetzt wurde, ist die vorhergehende laserendoskopische Passagewiederherstellung der Tumorstenose. In 2wöchigen Abständen wird bis zu 3mal endocavitär mit einer Dosis von 7 Gy bestrahlt. Bei kontinuierlicher endoskopischer Patientenüberwachung ist die Tubusimplantation bei besserer Lebensqualität und vergleichbaren Überlebenszeiten vermeidbar.     

The effects of iridium on the renal function of female Wistar rats

Despite the widespread use of iridium (Ir) in catalytic converters for improved capacity for reducing carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NO_x) emissions, there is a lack of studies that have assessed possible toxicological hazards of exposure to Ir. The present investigation indicates that female Wistar rats exposed to Ir in the drinking water for 90 days displayed renal toxicity based on the elevated urinary retinol binding protein (RBP) and albumin. The RBP was more sensitive to albumin, showing significant increases at 0.01 mg/L.     

Endovaskuläre Ir-192-HDR-Brachytherapie zur Vermeidung einer intimalen Hyperplasie in peripheren Gefäßen nach PTA und Stentimplantation

Background

The percutaneous transluminal angioplasty (PTA) is the “golden standard” in the therapy of vessel occlusions due to arteriosclerotic plaques. In spite of all improvements of the technique and the equipment with and without stent implantation there is still a restenosis rate of 40%.

Patients and Methods

Endovascular brachytherapy with an iridium-192 HDR source was performed in cases of a restenosis due to intimal hyperplasia which occurred within 6 months after a former PTA. After PTA and stent implantation a 9-French ReKa catheter was positioned with the tip 2 cm below the stent. This catheter served a centering device and as a guide for the 5-French appliator. After determination of the isodose and individual planning a dose of 12 Gy to 3 mm source distance was applied. After this procedure the patient received heparin for 72 hours followed by marcumar.

Results

From May 1990 until June 1996 28 patients (21 male, 7 female) were treated after PTA and stent implantation with endovascular brachytherapy. All patients had clinical relevant restenosis or reocclusion of the arteria femoralis. The follow-up time ranges from 2 to 71 months. Twenty-seven patients had a reasonable follow-up time longer than 6 months. Twenty-five patients could be followed: 4 patients had no or only minimal flow in the treated area, 2 patients moved with an unknown address, 1 patient died without any follow-up examination. No side effects of the radiation appeared.

Conclusion

Regarding the small number of patients endovascular brachytherapy with iridium 192 HDR seems to be a save and useful adjuvant treatment form to avoid intimal hyperplasia after PTA.     

Results of high dose-rate brachytherapy boost before 2D or 3D external beam irradiation for prostate cancer

Background and purpose

To evaluate biochemical control and treatment related toxicity of patients with localized adenocarcinoma of the prostate treated with high dose-rate brachytherapy (HDRB) combined with conventional 2D or 3D-conformal external beam irradiation (EBI).

Material and methods

Four-hundred and three patients treated between December 2000 and March 2004. HDRB was delivered with three fractions of 5.5-7 Gy with a single implant, followed by 45 Gy delivered with 2D or 3D conformal EBI.

Results

The median follow-up was 48.4 months. Biochemical failure (BF) occurred in 9.6% according to both ASTRO and Phoenix consensus criteria. Mean time to relapse was 13 and 26 months, respectively. The 5-year BF free survival using the ASTRO criteria was 94.3%, 86.9% and 86.6% for the low, intermediate and high risk groups, respectively; using Phoenix criteria, 92.4%, 88.0% and 85.3%, respectively. The only predictive factor of BF in the multivariate analysis by both ASTRO and Phoenix criteria was the presence of prostate nodules detected by digital palpation, and patients younger than 60 years presented a higher chance of failure using Phoenix criteria only.

Conclusions

Treatment scheme is feasible and safe with good efficacy.