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Biomedical subjects

J C Acevedo

Publications and source records attributed to J C Acevedo.

11 recordsLinked to original sources
PubMed2001

Sentinel lymph node mapping in melanoma with technetium-99m dextran.

PURPOSE: The aim of this work is to evaluate the capability of Tc99m B Dextran as a lymphoscintigraphic agent in the detection of the sentinel node in skin lesions. MATERIALS AND METHODS: Forty-one patients with melanomas (39) and Merkel cell tumors (2) had perilesional intradermal injection of Tc99m-Dextran 2 hours before surgery. Serial gamma camera images and a handheld gamma probe were used to direct sentinel node biopsy. RESULTS: In 39/41 patients, lymph channels and 52 sentinel nodes (one to three sentinel nodes/patient) could be visualized. In one patient, with a dorsal melanoma, no lymph channels or lymph nodes could be demonstrated on the images and only minimal radioactivity was found in the regional nodes with the probe. Another patient with a facial lesion failed to demonstrate lymph channels or nodes. No adverse reactions were observed. CONCLUSION: Tc99m-Dextran provided good definition of lymph channels and sentinel node localization, without the risks related to the use of potentially hazardous labeled materials of biological origin.

Adolescent↗
PubMed1999

Swine model of arterial bifurcation aneurysm.

OBJECTIVE: To create an arterial bifurcation aneurysm model in swine and evaluate it with digital subtraction angiography (DSA). METHODS: Ten swine were used for constructing the arterial bifurcation aneurysm models. Seven pigs underwent subsequent intraarterial DSA. Both surgical procedure and transarterial angiography were carried out under anesthesia with mechanical ventilation after tracheal intubation. RESULTS: Bifurcation aneurysms were surgically created in ten animals. After surgical procedure, 2 pigs died from aneurysmal rupture and one died of anesthetic overdose. DSA was performed in all other 7 animals and it demonstrated 6 patent aneurysms and one occluded. Three of the 6 patent bifurcation aneurysms were wide-necked and 3 were narrow-necked. CONCLUSION: Arterial bifurcation aneurysm model can be successfully constructed in swine. It will provide us with an in vivo model to observe and develop therapeutic devices, teach endovascular techniques, and study aneurysmal hemodynamics.

Aneurysm↗
PubMed1998

Aneurysmal remnants after microsurgical clipping: classification and results from a prospective angiographic study (in a consecutive series of 305 operated intracranial aneurysms).

The aim of this prospective study, carried out in a consecutive series of 305 microsurgically clipped aneurysms, was to check the absence of an aneurysmal remnant on post-operative angiography, and if a remnant was found to quantify its size in order to consider additional clipping to avoid the risk of rebleeding. Out of the 305 aneurysms, 292 (96%) were located in the anterior and 13 (4%) in the posterior circulation. Post-operative angiography was performed on average two weeks after surgery. Determination of the presence or not of an aneurysmal remnant and its quantification was done by an independent observer (JCA). Aneurysmal remnants were classified into 5 grades: grade I: less than 50% of neck size, grade II: more than 50% of neck size, grade III: residual lobe of a multilobulated sac, grade IV: residual sac of less than 75% of aneurysmal size and grade V: residual sac of more than 75% of aneurysmal size. Correlations between presence (and size) of the remnant and anatomical-surgical data obtained from the operative report were studied. Clipping was considered incomplete in 18 of the 305 aneurysms (5.9%). The group with residual neck only (grade I = 8 cases, Grade II = 4 cases) amounted to 4% of the whole series, whereas the group with residual neck + sac (grade III = 4, grade IV = 1, Grade V = 1) to 1.9%. Only this latter group was amenable to re-operation for complementary clipping without creating a stenosis of the parent artery. Our results are in the range of those of other published series. Anatomical-surgical factors for predisposition to incomplete clipping are discussed. The rates of sac obliteration using microsurgical clipping are to be compared with those recently achieved by electrically detachable coiling. The classification which we have developed is proposed for future comparison with endovascular results.

Adolescent↗
PubMed1997

Microvascular decompression for the treatment of hemifacial spasm. Retrospective study of a consecutive series of 75 operated patients--electrophysiologic and anatomical surgical analysis.

The authors report the results of a series of 75 patients operated on for hemifacial spasm by the same surgeon between October 1981 and January 1997. Microsurgical vascular decompression was performed through a retromastoid approach in contralateral position. The conflicting vessel was identified as the posterior inferior cerebellar artery in 41.3% of the cases, the anterior inferior artery in 38.6%, and the vertebrobasilar complex in 18.7%. Follow-up varied from 1 month to 13 years (with a mean duration of 5 years and 2 months). The outcome was excellent (total improvement) in 57 cases, good (> 75% improvement) in 11 cases, fair (< 75%) in 4 cases and poor in 3 cases. Neurological complications included deafness or hearing loss in 3 cases (2 occurred in the absence of intraoperative monitoring and the other during the first part of the series) and facial paralysis in 1 case. Brainstem auditory evoked potential (BAEP) intraoperative monitoring should be performed to avoid postoperative auditory complications; a marked auditory loss was observed in only 1.6% of the 60 patients of our series who underwent BAEP intraoperative monitoring.

Adult↗
PubMed1997

[Postoperative arteriography in surgery for intracranial aneurysm. Prospective study in a consecutive series of 267 operated aneurysms].

OBJECTIVES: We present the results of a prospective study of post-operative angiographic data in a consecutive series of 267 intracranial aneurysms (in 217 patients) operated on by the same surgeon (M.S.). MATERIAL AND METHODS: All patients underwent a preoperative as well as a postoperative angiographic control. Besides, an analysis of the operative reports was done in order to correlate the surgical and angiographic data. RESULTS: Out of 267 operated aneurysms, 257 (96%) were located in the anterior circulation, and 10 (4%) in the posterior circulation. The surgical clipping was considered incomplete in 17 aneurysms (6.3%). Aneurysmal remnants were classified in 5 grades; grade I: remnant less than 50% of the neck size; grade II: remnant more than 50% of the neck size; grade III: remnant of a multilobed aneurysmal sac; grade IV: residual sac less than 75% of the aneurysmal size; and grade V: residual sac more than 75% of the aneurysmal size. The analysis of the operative reports helped in understanding the favoring factors of incomplete clipping: large neck and/or huge sized sac, insufficient exposure and dissection of the neck. The presence of a collateral artery with a large infundibulum in the vicinity of the neck-implantation zone on the parent artery. CONCLUSIONS: In most cases the surgeon can easily control peroperatively under the microscope, after puncture-evacuation of the sac, the watertightness of clipping and the absence of any residual neck or sac of the aneurysm. Therefore the remaining place for a postoperative arteriography can be limited to those cases when the surgeon has some doubt concerning the perfection of clipping, as well as for giant and/or "difficult" aneurysms. A re-operation or a complementary endovascular treatment can be discussed for remnants in graded III, IV or V. Knowledge concerning the percentages of aneurysm with neck remnant only and of aneurysms with sac remnant obtained by surgery is interesting at the present time when endovascular treatment is becoming popular. In our series they amounted at 4.1% and 2.2%, respectively. These percentages are those of a series comprising all types of aneurysms. Needless to say, that the percentage of incomplete occlusion will be less if only the aneurysms with small-sized neck were taken into account.

Adult↗
PubMed1988

Heterogeneous ventilation and perfusion: a sensitive indicator of lung impairment in nonsmoking coal miners.

Twenty life-long nonsmoking West Virginia coal-miners participated in a study to amplify the role of focal irregularities on regional ventilation (V) and perfusion (Q) and to develop an improved method for the early detection of coal-workers' pneumoconiosis. Their mean age was 59.3 yr and they averaged 35.2 years' exposure to coal dust. Conventional pulmonary function tests were supplemented by measurement of V, Q and lung volume (V), using radioactive Kr-81m, Tc-99m MAA and Xe-127, respectively, to determine regional abnormalities in lung function. A computer analysis of the regional distributions of V/V, Q/V and V/Q was performed, and their topographical distributions and indices of heterogeneity (HI) computed. V/V and Q/V were significantly reduced in the lower third, and increased in the upper two-thirds of the miners' lungs; V/Q was reduced in the upper half. The miners' V/V and Q/V were more heterogeneous (p less than 0.001) than that of eleven age-matched controls, with mean ventilation HI values of 0.190 +/- 0.027 and 0.133 +/- 0.011, respectively, and mean perfusion HI values of 0.206 +/- 0.022 and 0.164 +/- 0.041, respectively. P(A-a)O2 correlated positively (r = 0.72; p less than 0.001) with ventilation HI. Gas exchange was the most significant functional measurement, being abnormal in 19/20 subjects. In contrast, conventional spirometric measurements were within the predicted normal limits in all but four miners.

Adult↗
PubMed1981

Sensitivity of Kr-81m and Xe-127 in evaluating nonembolic pulmonary disease.

The relative sensitivities of Kr-81m and Xe-127 in detecting lung ventilation defects was evaluated in 80 patients with nonembolic pulmonary diseases. Krypton-81m ventilation images (500,000 count) were interdigitated with Tc-99m MAA perfusion images; both were compared with Xe-127 images. The distributions of the two gases were also compared on the basis of point-by-point computer analyses. Xenon-127 was found to be more sensitive than Kr-81m in clinical evaluations of scintiphotos--although they were equivalent by computer analyses--in indicating regions of impaired ventilation in patients with obstructive airways disease.

Computers↗
PubMed1972

Implantation of exogenous enzymatic activity in isolated alveolar macrophages.

Alveolar macrophages acquired the capacity to oxidize uric acid after exposure to uricase. Presumably this resulted from intracellular incorporation of the enzyme by endocytosis. This approach may provide a general method for (i) testing regulatory biochemical mechanisms, (ii) therapeutic replacement of deficient regulatory macromolecules, and (iii) studying environmental factors that produce genetic alterations.

Animals↗