A simple spectrophotometric method for the determination of copper in industrial, environmental, biological and soil samples using 2,5-dimercapto-1,3,4-thiadiazole.
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A simple spectrophotometric method is presented for the rapid determination of copper at a trace level using 2,5-dimercapto-1,3,4-thiadiazole (DMTD) as a new spectrophotometric reagent. The method is based on the reaction of non-absorbent DMTD in a slightly acidic (0.002-0.014 mol dm(-3) sulfuric acid) aqueous solution with copper(II) to produce a highly absorbent greenish-yellow chelate product that has an absorption maximum at 390 nm. The reaction is instantaneous and the absorbance remains stable for 24 h. The average molar absorption coefficient and Sandell's sensitivity were found to be 5.65 x 10(4) dm3 mol(-1) cm(-1) and 10 ng cm(-2) of CuII, respectively. Linear calibration graphs were obtained for 0.1-20 microg cm(-3) of CuII; the stoichiometric composition of the chelate is 1:2 (Cu:DMTD). A large excess of over 50 cations, anions and complexing agents (e.g. tartrate, oxalate, citrate, phosphate, thiourea, SCN-) do not interfere in the determination. The method was successfully used for the determination of copper in several Standard Reference Materials as well as in some environmental water samples, biological samples, soil samples and solutions containing both copper(I) and copper(II) and complex synthetic mixtures. The method has high precision and accuracy (s = +/-0.01 for 0.5 microg cm(-1)). (+info)
Treatment of basilar artery embolism with a mechanical extraction device: necessity of flow reversal.
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BACKGROUND AND PURPOSE: The success of local fibrinolysis in vertebrobasilar thromboembolism depends on the volume and composition of the clot. Since thrombolysis can also be time consuming and cause bleeding, we investigated the feasibility of a mechanical clot retraction device based on a nitinol basket advanced through a microcatheter. METHODS: Five patients with acute embolism of the basilar artery who presented with progressive stroke and impaired consciousness were included in a multicenter study (Neuronet Evaluation in Embolic Stroke Disease [NEED]). In 3 patients flow reversal was induced with the use of silicone balloons or coaxial catheters. Three patients required additional fibrinolysis. RESULTS: The device failed to retrieve the clots in our first 2 patients with distal basilar artery embolism. After successful recanalization by local fibrinolysis, both patients survived, 1 disabled and 1 with little residual impairment. In the next 3 patients the anterograde flow in the basilar artery was reversed during the short retraction period by temporarily blocking the vertebral or subclavian arteries. Two of these patients were completely recanalized by solely mechanical means; the third patient needed additional fibrinolysis before also being recanalized. All 3 patients survived: 1 remained disabled, 1 had almost a full recovery, and 1 became asymptomatic the day after the procedure. CONCLUSIONS: Mechanical thrombus extraction seems to be a feasible method for preventing infarction by rapid, complete, and safe recanalization of the basilar artery. We recommend the use of flow control to support retrieval of the thrombus (which the proximal flow would otherwise keep in place like a cork) and to protect the distal vessels from embolization by fragments. (+info)
Sirolimus-eluting stents for the treatment of obstructive superficial femoral artery disease: six-month results.
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BACKGROUND: Stent implantation for obstructive femoropopliteal artery disease has been associated with poor long-term outcomes. This study evaluated the effectiveness of shape memory alloy recoverable technology (SMART) nitinol self-expanding stents coated with a polymer impregnated with sirolimus (rapamycin) versus uncoated SMART stents in superficial femoral artery obstructions. METHODS AND RESULTS: Thirty-six patients were recruited for this double-blind, randomized, prospective trial. All patients had chronic limb ischemia and femoral artery occlusions (57%) or stenoses (average lesion length, 85+/-57 mm). Patients were eligible for randomization after successful guidewire passage across the lesion. Eighteen patients received sirolimus-eluting SMART stents and 18 patients received uncoated SMART stents. The primary end point of the study was the in-stent mean percent diameter stenosis, as measured by quantitative angiography at 6 months. The in-stent mean percent diameter stenosis was 22.6% in the sirolimus-eluting stent group versus 30.9% in the uncoated stent group (P=0.294). The in-stent mean lumen diameter was significantly larger in the sirolimus-eluting stent group (4.95 mm versus 4.31 mm in the uncoated stent group; P=0.047). No serious adverse events (death or prolonged hospitalization) were reported. CONCLUSIONS: The use of sirolimus-eluting SMART stents for superficial femoral artery occlusion is feasible, with a trend toward reducing late loss compared with uncoated stents. The coated stent also proved to be safe and was not associated with any serious adverse events. (+info)
A simple and rapid spectrophotometric determination of thallium(III) with trifluoperazine hydrochloride.
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A simple, sensitive and rapid spectrophotometric method was developed for the determination of thallium(III) using trifluoperazine hydrochloride (TFPH). The method is based on the oxidation of TFPH by thallium(III) in a phosphoric acid medium to form a red-colored radical cation with an absorption maximum at 505 nm. Beer's law is valid over the concentration range of 0.5 - 6.5 microg ml(-1) of thallium(III). The molar absorptivity and Sandell's sensitivity of the color system are 2.14 x 10(4) l mol(-1) cm(-1) and 0.0095 microg cm(-2), respectively. The optimum reaction conditions and other analytical parameters were evaluated. The tolerance limit of the method towards various ions usually associated with thallium has been studied. The proposed method has been successfully applied to the analysis of thallium in alloys, minerals, standard reference material, water, and urine samples. (+info)
Mid-term results and migration behaviour of a ti-alloy cemented stem.
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Between 1991 and 1994, 147 patients (154 hips) underwent a primary cemented total hip replacement using the Ultima ti-alloy, collarless, double-tapered stem and a UHMWPE cup. The average age at operation was 66.4 years. Ninety-one patients (97 hips) were available for review with an average follow-up of 76 months. The Harris hip score had improved from pre-operative average of 43.1 (12.5-65.0) to the latest score of 88.9 (67.5-100). There were 11 revisions in total, eight of which were for aseptic stem loosening. The results of Kaplan-Meier survival analysis, based on stem revision for aseptic loosening as an end-point, was 92% at 8 years. Early stem migration analysis at 2 years was possible in 114 cases using digitised radiographs analysed by the EBRA method. Sixty-three stems had not migrated and 35 migrated less than 2 mm with only one of these ending in failure. Sixteen stems showed early migration of more than 2 mm and five of these failed. Early stem migration is predictive of stem failure. Osteolytic lesions occurred in 12 femurs and four of these stems failed. (+info)
Titanium-alloy particles induced cyclooxygenase-2 in human macrophage-like cells in vitro.
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Prostaglandin E2 (PGE2) has been reported to be an important mediator in aseptic loosening and/or periprosthetic osteolysis in total joint arthroplasties. Previous studies have reported that human macrophages stimulated with particles in vitro release PGE2. However, they have not shown the expression of cyclooxygenases (COX) which are rate-limiting enzymes of PGE2 synthesis. We hypothesized that PGE2 production by activated macrophages is dependent upon the induction of COX-2, not upon the constitutive isozyme, COX-1. When we evaluated the expression of COX-1 and COX-2 in titanium-alloy particle-stimulated human macrophages, the expression of COX-2 mRNA was up-regulated by the particles, on the other hand, the expression of COX-1 mRNA was not affected. In addition, NS-398, a COX-2 inhibitor drastically suppressed up-regulated PGE2 production by the particles. These results provide strong evidence that PGE2 production by particle-stimulated macrophages is dependent upon the induction of COX-2, not COX-1. (+info)
Odontologic use of copper/aluminum alloys: mitochondrial respiration as sensitive parameter of biocompatibility.
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Copper/aluminum alloys are largely utilized in odontological restorations because they are less expensive than gold or platinum. However, tarnishing and important corrosion in intrabuccal prostheses made with copper/aluminum alloys after 28 days of use have been reported. Several kinds of food and beverage may attack and corrode these alloys. Copper is an essential component of several important enzymes directly involved in mitochondrial respiratory metabolism. Aluminum, in contrast, is very toxic and, when absorbed, plasma values as small as 1.65 to 21.55 microg/dl can cause severe lesions to the nervous system, kidneys, and bone marrow. Because mitochondria are extremely sensitive to minimal variation of cellular physiology, the direct relationship between the mitocondrial respiratory chain and cell lesions has been used as a sensitive parameter to evaluate cellular aggression by external agents. This work consisted in the polarographic study of mitochondrial respiratory metabolism of livers and kidneys of rabbits with femoral implants of titanium or copper/aluminum alloy screws. The experimental results obtained did not show physiological modifications of hepatic or renal mitochondria isolated from animals of the three experimental groups, which indicate good biocompatibility of copper/ aluminum alloys and suggest their odontological use. (+info)
Talent LPS AAA stent graft: results of a pivotal clinical trial.
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PURPOSE: We report results of a pivotal prospective clinical trial that compared standard surgical repair with endovascular exclusion of abdominal aortic aneurysm (AAA) with the Talent LPS stent graft system. METHODS: Between March 24, 1999, and September 19, 2000, 240 patients with AAA who underwent stent graft placement and 126 patients who concurrently underwent surgery to treat AAA were enrolled at 17 centers in the United States. All patients were considered to be at low risk from aortic surgery. Patients who underwent endovascular repair received a bifurcated Talent LPS stent graft; surgical control subjects underwent standard operative techniques. Inclusion criteria were AAA larger than 4.0 cm in diameter, with proximal neck > 5 mm long and 14 to 32 mm in diameter, and a 15 mm landing zone in at least one common iliac artery. Access requirements included one external iliac artery of 7 mm caliber or larger. Preoperative anatomic evaluation included computed tomography and angiography. After stent-graft placement, evaluation involved plain radiography and computed tomography performed before discharge and at 1, 6, and 12 months and yearly thereafter. RESULTS: There was no significant difference in early (<30 days) or late mortality between the two groups. Complications were slightly higher in the surgical cohort. The stent graft group did better in terms of procedure duration, requirement for general anesthesia and blood transfusion, and intensive care unit and hospital stay. There were three access or deployment failures. Immediate surgical conversion was necessary in only 1 patient, and late conversion in 5 additional patients. There were no aneurysm ruptures. Endoleak rate detected at CT (core laboratory validated) was 14% at 1 month, 12% at 6 months, and 10% at 12 months. CONCLUSIONS: Compared with surgical control subjects, patients with AAA treated with the Talent LPS stent graft had fewer complications and the same low operative mortality. Likewise, endovascular repair performed better than surgery in the perioperative period, as measured with several key procedural indicators. Long-term follow-up of patients with the stent graft will be essential to assess durability of these early results. (+info)