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Biomedical subjects

Carlos Miranda

Publications and source records attributed to Carlos Miranda.

17 recordsLinked to original sources
PubMed2006

Electrochemistry of copper complexes with macrocyclic polyamines containing pyrazole units.

The voltammetric behaviour of bi- and mono-nuclear complexes formed in solution by Cu(2+) with three polyazacyclophanes containing pyrazole units in aqueous solution is described. Cyclic and square wave voltammetric responses at glassy carbon electrodes indicate that the reduction of copper-macrocycle complexes in solution takes place in two successive one-electron per Cu transfer processes coupled with preorganization and protonation reactions that mimic the behaviour of superoxide dismutase. The electrochemistry of ternary Cu(2+)-receptor-dopamine complexes exhibits significant differences with respect to the protection of the neurotransmitter from post-electron transfer cyclization reactions.

Copper↗
PubMed2005

Moyamoya syndrome in an adolescent with essential thrombocythemia: successful intracranial carotid stent placement.

BACKGROUND: Essential thrombocythemia (ET) is a chronic myeloproliferative disorder with increased frequency of thrombotic events, including transient ischemic attacks (TIAs) and stroke. Moyamoya syndrome is a rare cerebrovascular disease characterized by progressive occlusion of intracerebral arteries with a typical "puff of smoke" angiographic pattern. We report the development of moyamoya syndrome in a patient with ET. CASE DESCRIPTION: The patient is an 18-year-old female who presented at age 13 with recurrent TIAs. Persistent thrombocytosis was found, a diagnosis of ET was made, and treatment with anagrelide was started. Despite normal platelet counts, she experienced recurrent TIAs and stroke. Severe stenosis of the supraclinoid segment of the left internal carotid artery (LICA) and abnormal collateral vessels were found, and moyamoya syndrome was diagnosed on the basis of the characteristic angiographic appearance. An intracranial stent was placed in the LICA, and since then, she has had an uneventful outcome after a 46-month follow-up. CONCLUSIONS: To our knowledge, the development of moyamoya phenomenon has not been reported in ET, and the relationship between these 2 disorders remains unclear. Besides, this is the first intracranial carotid stent implanted successfully in a patient with moyamoya.

Adolescent↗
PubMed2005

Synthesis of a novel series of 2-methylsulfanyl fatty acids and their toxicity on the human K-562 and U-937 leukemia cell lines.

The hitherto unknown 2-methylsulfanyldecanoic acid and 2-methylsulfanyldodecanoic acid were synthesized from methyl decanoate and methyl dodecanoate, respectively, through the reaction of lithium diisopropylamide and dimethyldisulfide in THF followed by saponification with potassium hydroxide in ethanol. Both alpha-methylsulfanylated FA were cytotoxic to the human chronic myelogenous leukemia K-562 and the human histiocytic lymphoma U-937 cell lines with EC50 values in the 200-300 microM range, which makes them more cytotoxic to these cell lines than decanoic and/or dodecanoic acid. The cytotoxicity of the studied FA toward K-562 followed the order 2-SCH3-12:0 > 2-SCH3-10:0 > 10:0 > 12:0 > 2-OCH3-12:0, whereas toward U-937 the cytotoxicity was 2-SCH3-10:0 > 2-SCH3-12:0 > 12:0 > 10:0 > 2-OCH3-12:0. These results indicate that the alpha-methylsulfanyl substitution increases the cytotoxicity of the C10 and C12 FA toward the studied leukemia cell lines.

Amsacrine↗
PubMed2005

Computer equipment used in patient care within a multihospital system: recommendations for cleaning and disinfection.

Computer hardware has been implicated as a potential reservoir for infectious agents. Leaders of a 22-hospital system, which spans North America and serves pediatric patients with orthopedic or severe burns, sought to develop recommendations for the cleaning and disinfection of computer hardware within its myriad patient care venues. A task force comprising representatives from infection control, medical affairs, information services, and outcomes management departments was formed. Following a review of the literature and of procedures within the 22 hospitals, criteria for cleaning and disinfection were established and recommendations made. The recommendations are consistent with general environmental infection control cleaning and disinfection guidelines, yet flexible enough to be applicable to the different locales, different computer and cleaning products available, and different patient populations served within this large hospital system.

Computers↗
PubMed2005

Endovascular reconstruction by means of stent placement in symptomatic intracranial atherosclerotic stenosis.

OBJECTIVE: Patients with intracranial atherosclerosis who fail antithrombotic therapy have a poor prognosis. The high rate of recurrent stroke warrants testing alternative treatments such as intracranial angioplasty. METHODS: We present our experience in the treatment of 104 patients (age range, 54-82 years; mean age, 67 years) with symptomatic intracranial atherosclerotic stenoses despite medical therapy who underwent stent-assisted angioplasty. Patient records were retrospectively analysed for location and degree of stenosis, regimen of antiplatelet agents, devices used, procedure-related complications and adverse events. Clinical (Modified Rankin Scale) and radiographic outcomes were obtained 24 hours, 1 month and 3-6 months after treatment. Sixty-five lesions (62.5%) were located in the posterior circulation. Mean stenosis was 75.4%. RESULTS: In all patients, the angiographic degree of stenosis was reduced to less than 30%. One stent was implanted in 66 patients (63%), and two or more in 38 patients (37%). Modified Rankin Scale (mR) was 1-2 in 67.5% of the cases, 3-4 in 25.9%, 5 in 2.8%, 6 in 3.8%. Procedural morbidity was 5.7% and procedural mortality was 3.8%. Angiographic follow-up was available in 58 patients (55.7%) and the restenosis rate was 12.5%. DISCUSSION: In selected patients, endovascular revascularization of intracranial arteries by means of stent-assisted angioplasty is technically feasible, effective and safe.

Aged↗
PubMed2005

Partial aortic obstruction improves cerebral perfusion and clinical symptoms in patients with symptomatic vasospasm.

OBJECTIVE: Stroke studies in animals showed that aortic obstruction increases cerebral blood flow (CBF) and reduces infarct size. In this study we evaluate the safety and efficacy of a device providing partial and transitory aortic obstruction. METHODS: We report the results in 24 selected patients with symptomatic vasospasm by aneurysmal subarachnoid hemorrhage treated by partial and transitory aortic obstruction with a novel device (NeuroFlo, CoAxia, MN). Aneurysms were secured by coils prior to the procedure. We studied the adverse effects related to the aorta-obstructing device, and changes in CBF and neurological outcome. RESULTS: Mean flow velocity increased in both middle cerebral arteries over 15%, and the score in the National Institute of Health Stroke Scale decreased >or=2 point in 20 patients (83%). During the procedure, three patients developed symptoms that were controlled. At 30 days follow-up, three patients had 6 points (unrelated death), three had 3 points, six had 1 point, and 12 had 0 points, in the modified Rankin scale. DISCUSSION: Partial aortic obstruction was safe, the cerebral blood flow increased without inducing significant hypertension and the neurological defects improved in most of the patients. Efficacy with a better level of evidence will be determined by a randomized study.

Adult↗
PubMed2005

Buenos Aires experience with the Neuroform self-expanding stent for the treatment of intracranial aneurysms.

OBJECT: The authors report their experience with the use of the Neuroform Microdelivery System for intravascular reconstruction. They assess the technical feasibility of the system, the efficacy of the combined application of stent and detachable coils, and the follow-up findings. METHODS: Fifty patients found to harbor a complex wide-necked intracranial aneurysm were selected for the study. Different strategies were chosen and the performance and technical success of the device were evaluated. Stent placement was recorded as optimal or suboptimal with respect to the stent position. Clinical and angiographic follow-up examinations were obtained. Forty-six patients with 48 intracranial aneurysms were treated, leading to a technical success rate of 92%. Forty-two lesions were located in the anterior circulation. In every case the dome/neck ratio was less than 2 and the mean aneurysm size in these patients was 8.8 mm. The most frequent clinical presentation was subarachnoid hemorrhage in 48% of cases. Stent placement was optimal in 81.2% of cases and suboptimal in 18.8%. In 31% of cases, the investigators encountered difficulties in placing the Neuroform stent. Clinical follow up was recorded in all patients and angiographic follow up was obtained in 63%. There were no cases of repeated hemorrhage. In a single case in which only the stent was implanted progressive thrombosis was identified during the follow-up period. The procedure-related morbidity and mortality rates were 8.6 and 2.1%, respectively. CONCLUSIONS: On the basis of the results, the authors conclude that the Neuroform self-expanding stent is a flexible and useful device that can be readily and safely maneuvered through tortuous intracranial vessels, enabling the endovascular treatment of complex wide-necked aneurysms. Early in the authors' experience, stent delivery presented difficulties; however, a second generation of devices has resolved this limitation. Although the early results are promising, the long-term benefit of this technique has to be proved by angiographic and clinical follow-up examinations.

Adult↗
PubMed2004

New 1H-pyrazole-containing polyamine receptors able to complex L-glutamate in water at physiological pH values.

The interaction of the pyrazole-containing macrocyclic receptors 3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.1(11,14)]-octacosa-1(27),11,14(28),24-tetraene 1[L1], 13,26-dibenzyl-3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.1(1)(1,14)]-octacosa-1(27),11,14(28),24-tetraene 2[L2], 3,9,12,13,16,22,25,26-octaazatricyclo-[22.2.1.1(11,14)]-octacosa-1(27),11,14(28),24-tetraene 3[L3], 6,19-dibenzyl-3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.1(11,)(14)]-octacosa-1(27),11,14(28),24-tetraene 4[L4], 6,19-diphenethyl-3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.1(11,14)]-octacosa-1(27),11,14(28),24-tetraene 5[L5], and 6,19-dioctyl-3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.1(11,14)]-octacosa-1(27),11,14(28),24-tetraene 6[L6] with l-glutamate in aqueous solution has been studied by potentiometric techniques. The synthesis of receptors 3-6[L3-L6] is described for the first time. The potentiometric results show that 4[L4] containing benzyl groups in the central nitrogens of the polyamine side chains is the receptor displaying the larger interaction at pH 7.4 (Keff = 2.04 x 10(4)). The presence of phenethyl 5[L5] or octyl groups 6[L6] instead of benzyl groups 4[L4] in the central nitrogens of the chains produces a drastic decrease in the stability [Keff = 3.51 x 10(2) (5), Keff = 3.64 x 10(2) (6)]. The studies show the relevance of the central polyaminic nitrogen in the interaction with glutamate. 1[L1] and 2[L2] with secondary nitrogens in this position present significantly larger interactions than 3[L3], which lacks an amino group in the center of the chains. The NMR and modeling studies suggest the important contribution of hydrogen bonding and pi-cation interaction to adduct formation.

Biomimetic Materials↗
PubMed2003

The first total synthesis of the marine fatty acid (+/-)-9-methoxypentadecanoic acid: a synthetic route towards mid-chain methoxylated fatty acids.

The marine fatty acid (+/-)-9-methoxypentadecanoic acid was synthesized for the first time in seven steps (7.8% overall yield) starting from commercially available 9-decen-1-ol. The key step in the synthesis was the coupling of pentylmagnesium bromide with 1-benzyloxy-9,10-epoxydecane under 1,5-cyclooctadiene copper (I) chloride catalysis. Nuclear magnetic resonance data are provided for the first time for this type of methoxylated fatty acids and the synthetic approach utilized is of general applicability since it can be used in the synthesis of other mid-chain methoxylated fatty acids. This synthetic methodology should afford sufficient quantities of these fatty acids for biological evaluation. The spectral data obtained for the title compound will also be helpful in subsequent characterizations of other mid-chain methoxylated fatty acids using nuclear magnetic resonance spectroscopy.

Fatty Acids↗
PubMed2003

Covered stent as an innovative tool for tumor devascularization and endovascular arterial reconstruction.

A temporal paraganglioma was pre-operatively embolised with particles and due to the fact that the internal carotid artery was encased by the tumor and that multiple petrous feeders precluded safe embolization, we decided to implant a balloon-expandable covered stent. On immediate post-procedural angiography, the arterial diameter was restored and a complete devascularization of the tumor was achieved. The tumor was operated with minimal blood loss and the carotid artery was released from surrounding tumor using the frame of the stent as a surgical limit. Covered stents may become a valuable tool for pre-operative tumor devascularization and arterial reconstruction especially when dealing with hypervascular tumors of the cranial base that encase the carotid artery.

Adult↗
PubMed2003

Reconstructive endovascular approach for a cavernous aneurysm in infancy.

We report a unique case of endovascular arterial reconstruction using stent and coils in a symptomatic cavernous aneurysm presented in infancy. A 3-year-old infant presented with a partial cavernous sinus syndrome secondary to a bilobulate cavernous aneurysm with subarachnoid extension. Direct clipping represented a considerable challenge and trapping after bypass grafting was considered to risky. A combined endovascular approach using stent and coils was performed. A 4 x 18 mm balloon-expandable stent was then placed across the aneurysm orifice allowing the complete obliteration of the remnant with coils implanted through the stent mesh. Digital substraction angiography documented patency of the ICA lumen and complete obliteration of the aneurysm. A 24-months angiographic follow-up was performed confirming persistent aneurysm exclusion and patency of the parent vessel with no signs of in-stent de novo stenosis. Reconstructive endovascular technique using stent and coils allowed the treatment of a complex vascular condition. The cavernous lesion was excluded from the circulation while preserving normal flow through the parent vessel and its branches. Long-tern follow up is a major concern, specially in pediatric patients but the 24 months angiographic follow-up is encouraging.

Carotid Artery Diseases↗
PubMed2002

Phospholipid fatty acid composition of Gorgonia mariae and Gorgonia ventalina.

The phospholipid fatty acid composition of the Caribbean gorgonians Gorgonia mariae (Bayer) and Gorgonia ventalina (Linnaeus) is described for the first time. The main phospholipids identified were phosphatidylethanolamine, phosphatidylcholine, and phosphatidylserine. The main fatty acids were 14:0, 16:0, 18:3(n-6), 18:4(n-3), 18:2(n-6), 20:4(n-6), 22:6(n-3), and 24:5(n-6). In both G. mariae and G. ventalina n-6 polyunsaturated fatty acids predominated over the n-3 family. In addition, the 7-methyl-6(E)-hexadecenoic acid was identified in both gorgonians. The occurrence of tetracosapolyenoic fatty acids in the genus Gorgonia is also reported for the first time.

Animals↗
PubMed2002

Partially clipped intracranial aneurysm obliterated with combined stent and coil implantation.

PURPOSE: To report a case of endovascular stent placement to assist stable coil deployment in a symptomatic, wide-necked, partially clipped aneurysm. CASE REPORT: A 48-year-old woman presented for endovascular treatment of a symptomatic posterior communicating artery aneurysm remnant that was surgically clipped 10 years ago. A 3.5-mm x 12-mm balloon-expandable stent was placed across the aneurysm orifice followed by complete obliteration of the remnant with coils implanted through the stent mesh. Digital subtraction angiography documented continued patency of the arterial lumen and complete obliteration of the aneurysm at 11 months. CONCLUSIONS: Partial aneurysm clipping may assist or complicate secondary interventional procedures and interfere with correct visualization of the neck. Stent placement obviates the need for the balloon-assist method of coil embolization for wide-necked aneurysm remnants, acting as a mechanical barrier to hold the coils in a very unfavorable anatomy.

Angiography, Digital Subtraction↗
PubMed2002

Endovascular reconstruction of intracranial arteries by stent placement and combined techniques.

OBJECT: The authors investigated the feasibility, safety, and short-term outcome of stent treatment for intracranial aneurysms, stenoses, and dissections. METHODS: One hundred twenty-three consecutive patients with intracranial saccular, dissecting, and fusiform aneurysms, atherosclerotic lesions, and dissections were selected for intracranial stent implantation with or without adjunctive coil placement. One hundred eleven patients (mean age 47 years, range 3-73 years) underwent stent treatment; 12 patients (9.8%) were not treated. These 111 patients were divided into four groups: in Group 1 there were 62 patients with saccular aneurysms; Group 2 included nine patients (10 lesions) with dissecting or fusiform aneurysms; in Group 3 there were 36 patients with symptomatic intracranial atheromatous stenoses of more than 50%; and Group 4 included four patients with symptomatic intracranial dissections. All patients underwent computerized tomography scanning and/or magnetic resonance imaging and cerebral digital subtraction angiography preoperatively. Of the 72 aneurysms in Groups 1 and 2, 59 (82%) were treated with combined endovascular stent implantation and endosaccular coil placement. In 67 aneurysms (93%) we achieved complete or nearly complete obliteration. All patients with arterial narrowing achieved residual stenoses of less than 30% postangioplasty. One patient required repeated angioplasty. The morbidity rate in the series was 10.9% and the mortality rate was 6.3%. CONCLUSIONS: These findings indicate that stent treatment is feasible and seems to be an effective modality for arterial reconstruction. This versatile tool allows the treatment of a wide variety of challenging intracranial lesions.

Adolescent↗
PubMed2002

Angioplasty and stent placement in intracranial atherosclerotic stenoses and dissections.

BACKGROUND AND PURPOSE: Stent placement has been shown to increase the safety and effectiveness of balloon angioplasty in cervical carotid disease. Here, the authors investigated the feasibility, safety, and short-term outcome of stent-assisted angioplasty for the treatment of intracranial stenoses. METHODS: Thirty-four patients (age range, 12-77 years; mean age, 54 years) with symptomatic intracranial atherosclerotic lesions and dissections that produced stenosis of more than 50% were selected and treated with stents. Eighteen lesions (53%) were located in the anterior circulation, and 16 (47%) were in the vertebrobasilar complex. The mean stenosis was 75%. RESULTS: At follow up, 21 patients (62%) improved clinically, 11 (32%) remained stable, and the condition of two patients (6%) deteriorated. In all patients, the angiographic degree of stenosis was reduced to less than 30%. In 10 patients (29%), two or more stents were implanted: Two stents were implanted in six patients, and three, in four patients. The transient procedural morbidity rate was 12%, and the transient neurologic morbidity rate was 6%. One patient had hemorrhagic transformation due to reperfusion and died, and another patient had a massive myocardial infarction after 5 months. Twenty patients were followed up with angiography for at least 6 months, and none required repeat angioplasty. CONCLUSION: Endovascular revascularization of intracranial arteries by means of stent-assisted angioplasty is technically feasible, effective, and safe in selected patients.

Adolescent↗