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Biomedical subjects

J Burgos

Publications and source records attributed to J Burgos.

At least 19 recordsLinked to original sources
PubMed2002

Long-term outcome of patients with asystole induced by head-up tilt test.

AIMS: To analyse the long-term outcome of the largest reported cohort of patients presenting asystole during head-up tilt test. METHODS AND RESULTS: Since 1990, 1322 patients with syncope of unknown origin have undergone tilt-table testing. Of those, 330 patients (24 X 9%) presented an abnormal response (syncope or pre-syncope). Furthermore, 58 of those patients (17 X 5%) suffered a period of asystole (> or = 3000 ms) during the test. Asystole (median (interquartile range)) lasted 10 (4, 19 X 2) s (range 3-90). Two different protocols (angles) of tilting (Westminster (60 degrees) n=1124; isoproterenol (80 degrees) n=198)) influenced the time to the syncopal episode (13 (6 X 5, 20 X 5) vs 2 (1, 6 X 5) min, P=0,0005) but not the duration of the asystole. During this period, therapy for asystole featured three different stages: first patients were treated with pacemakers; later drug therapy (metoprolol and/or etilefrine) was recommended; lastly (from 1995), no specific treatment was given. In a cohort age- and gender-matched study, those patients without were compared to those with asystole in a 2:1 basis. During 40 X 7 months of follow-up (17 X 7, 66 X 8), 12 patients (20 X 6%) with asystole had syncopal recurrences. Furthermore, 34 patients (28 X 8%) without asystole presented syncopal episodes during a follow-up of 51 X 6 months (29 X 3, 73 X 1) (P=ns). The Kaplan-Meier analysis in patients with and without asystole showed a mean time free of recurrence of 92 X 6 +/- 6 months vs 82 X 6 +/- 4 X 7 months (P=ns). The previous number of syncopes had a significant relationship with recurrences (P=0 X 002), but not therapy. There were no cardiac related deaths. CONCLUSIONS: (1) Asystole during head-up tilt test does not imply a malignant outcome and syncope recurrence is low; (2) pacemaker or drug therapy do not significantly influence outcome which correlates to the previous number of syncopal episodes but not to gender, age, asystole occurrence, asystole duration and timing to asystole during head-up tilt test; (3) tilting protocol (angle) might influence time to and incidence of asystole during head-up tilt test.

Adult↗
PubMed2001

Manothermosonication of foods and food-resembling systems: effect on nutrient content and nonenzymatic browning.

The effect of manothermosonication (MTS), an emergent technology for food preservation, on thiamin, riboflavin, carotenoids, and ascorbic acid was evaluated in milk and orange juice. The effect of both heat treatment and MTS on several compounds produced in nonenzymatic browning in model systems was also studied. MTS does not affect significantly the nutrient content studied. However, it changes the behavior of nonenzymatic browning. No formation of 5-(hydroxymethyl)-2-furfuraldehyde (HMF) was detected in fruit juice model systems after heat and MTS treatments at the experimental conditions used. In a milk-resembling system, free HMF formation by MTS is higher compared to that by heat treatment. As the MTS temperature increases, free HMF production by both treatments equaled on another. For bound HMF the production rate is lower by MTS than by heat treatment under the experimental conditions used. Formation kinetics of brown pigments and that of fluorescent compounds are different for both treatments. Fluorescence and brown pigment production are faster in MTS.

Animals↗
PubMed2001

Age and gender differences in basal and isoprenaline protocols for head-up tilt table testing.

AIMS: Syncope is a common occurrence, the prevalence of which increases with age, and among the multiple causes of syncope, neurally mediated syncope is thought to be a frequent cause in the young and in the elderly. Head-up tilt table testing (HUT) has become the diagnostic test of choice for neurally mediated syncope, the response to which varies clearly with age. The purpose of this study is to report the differences among patients suffering syncope referred for HUT, and the influence of age and gender on HUT results (percentage of positive responses and response patterns) in two study protocols (basal and isoprenaline). METHODS AND RESULTS: One thousand, two hundred and nineteen patients with syncope were referred to the authors' Cardiology Department for HUT from September 1990 to April 2000; 1061 undergoing basal HUT (Group A) and 158 undergoing isoprenaline tilt table testing (Group B). Complications were noted in neither protocol. Females were more frequent among young people, and males in the elderly (P<0.05). Head-up tilt table testing was abnormal in 259 (24.4%) patients in Group A and in 85 (53.7%) patients in Group B (P<0.05), and no gender differences were observed. The positive rate of tests in men and women significantly declined with age in Group A (P<0.05), but not in Group B (P=ns). There were no differences in the patterns of haemodynamic collapse in both groups. CONCLUSIONS: In the study of syncope, basal HUT has a high positive rate in young people; a decrease in positive rate with age suggests, however, the need for using another protocol with a similar diagnostic accuracy in the elderly.

Adult↗
PubMed2000

Early diagnosis of recurrence of Trypanosoma cruzi infection by polymerase chain reaction after heart transplantation of a chronic Chagas' heart disease patient.

Heart transplantation is contraindicated as an effective treatment for end-stage Chagas' heart disease because of post-operative recurrence of Trypanosoma cruzi infection and reactivation of disease after immunosupression. In a follow-up study of a heart transplanted patient with Chagas' disease, we prospectively evaluated the usefulness of the polymerase chain reaction (PCR) for early diagnosis of reactivation. We monitored post-operative recurrence of Trypanosoma cruzi infection with microscopic observation of the parasite in peripheral blood (Strout's method), endomyocardial biopsies (EMBs), skin lesions, and 2 PCR assays, based on the amplification of specific T cruzi kinetoplastid and nuclear DNA sequences. During follow-up, parasite DNA was amplified in blood samples and EMB sections 41 days before we observed patent parasitemia and cutaneous manifestations of reactivation, proving that PCR is much more sensitive than direct microscopic observation for early diagnosis of disease reactivation in heart-transplanted Chagas' disease patients.

Animals↗
PubMed1999

A shuttle walk test for assessment of functional capacity in chronic heart failure.

BACKGROUND: Peak oxygen uptake (peak VO(2)) is a reference parameter in the assessment of functional capacity of patients with chronic heart failure, but the procedure for cardiopulmonary exercise testing with expired gas analysis is complex and expensive, so more simple and available methods are desirable. METHODS: We compared the usefulness of a time-limited walk test, the 6-minute walk test (6-MT), with that of a symptom-limited walk test, the shuttle walk test (SWT), in the evaluation of patients with moderate to severe chronic heart failure. We prospectively studied 46 clinically stable patients in New York Heart Association class II to IV heart failure with left ventricular ejection fraction <40% (aged 53 +/- 10 years, ejection fraction 23% +/- 8%, New York Heart Association functional class 2.8 +/- 0.7). Each patient performed two 6-MT, two SWT and a cardiopulmonary exercise testing within 2 weeks. RESULTS: We found a close correlation between distance walked in SWT and peak VO(2 ) (r = 0.83, P <.001) and a moderate correlation between distance in 6-MT and peak VO(2) (r = 0.69, P <.001). Both walk tests showed to be reproducible after just one practice walk. All patients who walked > 450 m in SWT had a peak VO(2) >14 mL/kg/min. The overall discriminatory accuracy for SWT distance was greater than that for 6-MT distance for predicting a peak VO(2 ) <14 mL/kg/min (area under receiver operator characteristic curves 0.97 and 0.83 respectively, P =.02). Stepwise multivariate regression analysis, including clinical, exercise testing, echocardiographic, radionuclide-angiographic, and rest hemodynamic data, showed that distance walked in SWT was the only independent predictor of peak VO(2) (P <.001) and the strongest predictor of percent achieved of age- and sex-predicted peak VO(2) (%PVO(2)) (P <.001), with only age offering additional information (P =.02). CONCLUSIONS: The SWT shows to be a feasible and safe method to evaluate patients with chronic heart failure that strongly and independently predicts peak VO(2) and %PVO(2.) This symptom-limited walk test seems to be more useful than 6-MT in the assessment of functional capacity in these patients.

Adult↗
PubMed1999

Inactivation of heat-resistant pectinmethylesterase from orange by manothermosonication.

Pectinmethylesterase of navel oranges shows two fractions greatly differing in thermostability. The most thermostable fraction accounts for approximately 10% of total activity. The thermal inactivation of this fraction follows first-order kinetics both in 5 mM, pH 3.5, citrate buffer and in orange juice at the same pH, showing a z value of 5.1 degrees C and an activation energy (E(a)) of 435 kJ mol(-)(1) K(-)(1). The heat resistance of the enzyme is approximately 25-fold higher in the juice than in citrate buffer. When ascorbic acid, sucrose, glucose, and fructose are added to the citrate buffer at the concentrations found in orange juice, the heat resistance of the enzyme increases 3-fold. The addition of pectin at 0.01% concentration multiplies it by a factor of 50. Manothermosonication (MTS), the simultaneous application of heat and ultrasound under moderate pressure (200 kPa), at 72 degrees C, increases the inactivation rate 25 times in buffer and >400 times in orange juice. MTS inactivation shows a higher z value (35.7 degrees C) and lower E(a) (56.9 kJ mol(-)(1) K(-)(1)) than simple heating.

Carboxylic Ester Hydrolases↗
PubMed1998

Anterior endoscopic approach to the thoracolumbar spine.

STUDY DESIGN: A technique for anterior endoscopic exposure of the thoracolumbar spine is described. OBJECTIVE: To develop an endoscopic approach to the thoracolumbar spine with fewer complications than are encountered in the conventional approach. SUMMARY OF BACKGROUND DATA: The efficacy of the anterior endoscopic approach to the thoracic spine has been shown. The thoracolumbar hinge is usually approached by open surgery. METHODS: The study was performed in three stages. The first phase was carried out on experimental animals (pigs). Once the bases were established, the approach was studied in fresh cadavers. Finally, it was performed on three patients with thoracolumbar scoliosis who required discectomy and anterior release. RESULTS: After a series of attempts on the animals, it was found that the most effective method for exposure of the thoracolumbar spine was the initial thoracoscopic approach followed by the retroperitoneal endoscopic approach. This was confirmed in cadavers. When applied to the clinical situation, there were no significant complications in any of the patients treated with this method, and postoperative pain and discomfort were minimal. CONCLUSIONS: The anterior endoscopic approach to the lumbar spine involves minor trauma, results in rapid recovery and less pain, and produces good results aesthetically.

Adolescent↗
PubMed1998

Hydrophilic membrane-based humidity control.

A dehumidification system for low gravity plant growth experiments requires the generation of no free-liquid condensate and the recovery of water for reuse. In the systems discussed in this paper, the membrane is a barrier between the humid air phase and a liquid-coolant water phase. The coolant water temperature combined with a transmembrane pressure differential establishes a water flux from the humid air into the coolant water. Building on the work of others, we directly compared different hydrophilic membranes for humidity control. In a direct comparison of the hydrophilic membranes, hollow fiber cellulose ester membranes were superior to metal and ceramic membranes in the categories of condensation flux per surface area, ease of start-up, and stability. However, cellulose ester membranes were inferior to metal membranes in one significant category, durability. Dehumidification systems using mixed cellulose ester membranes failed after operational times of only hours to days. We propose that the ratio of fluid surface area to membrane material area (approximately = membrane porosity) controls the relative performances among membranes. In addition, we clarified design equations for operational parameters such as the transmembrane pressure differential. This technology has several potential benefits related to earth environmental issues including the minimization of airborne pathogen release and higher energy efficiency in air conditioning equipment. Utilizing these study results, we designed, constructed, and flew on the space shuttle missions a membrane-based dehumidification system for a plant growth chamber.

Air Conditioning↗
PubMed1998

Comparative analysis of Epstein-Barr virus (EBV) detection by nested-PCR and non-isotopic in situ hybridization in nasopharyngeal carcinoma (NPC).

The aims of this study were two-fold: first, to assess the relative diagnostic performance of non-isotopic in situ hybridization (ISH) and the nested polymerase chain reaction (nested-PCR) applied to Epstein-Barr virus (EBV) detection in a series of 55 unselected nasopharyngeal carcinoma (NPC) cases and, secondly, to correlate these data with histopathological classification. Our study shows that in 76.36% of NPC cases positive nuclear signals were observed using EBV-ISH. Overall, EBV-ISH positivity varied according to histological type, in that undifferentiated carcinomas showed a higher proportion of positive cases than differentiated cell carcinomas, although ISH results do not show significant differences in relation to histological types when employing two different schemes (WHO and Micheau). However, in adequate quality DNA samples (54 NPC cases), EBV-DNA was detected in 100% of cases using a nested-PCR, supporting the previous view that all histological types of NPC are in reality variants of EBV-infected neoplasia. ISH-negative cases probably reflect a lower sensitivity than PCR, particularly when a small number of viral copies are present, as well as a variable technical effectiveness for detected EBV, independent of the NPC histological type.

Adolescent↗
PubMed1997

Traumatic proximal tibiofibular dislocation.

Proximal tibiofibular dislocation is an exceptional lesion. Rarer still is its presentation in childhood. We describe the clinical case of a 6-year-old boy, the victim of a road accident. He had a tibiofibular dislocation associated with a metaphyseal fracture of the tibia.

Child↗
PubMed1996

S-phase fraction identifies high-risk subgroups among DNA-diploid breast cancers.

The prognostic value of DNA content measured by means of flow cytometry was analyzed in formalin-fixed, paraffin-embedded samples from 231 breast cancer patients treated between 1984 and 1988, with a mean follow-up period of 55 months. We followed the guidelines of a Consensus Meeting held on this issue in Maine, USA, in 1992. DNA-diploid and -aneuploid tumors were evaluated separately for the fraction of cells in S-phase (SPF) contained in them, this being divided into three groups ('high', 'intermediate', and 'low'), defined by the 25th and 75th centile of the SPF-distribution corresponding to either DNA-diploid or DNA-aneuploid tumors. Unequivocally readable histograms were obtained from 174 samples (75.3%). A high SPF in diploid tumors was significantly associated with a higher recurrence rate (p = 0.015), a shorter disease-free survival (p = 0.014), advanced (IIIB) clinical stage (p = 0.034), and almost significantly with total survival (p = 0.055). In a multivariate Cox regression analysis, a high SPF in diploid tumors retained its independent prognostic power, being significantly associated with a shorter disease-free survival (p = 0.00049) and total survival (p = 0.0077). It also allowed to identify a subgroup with an ominous prognosis among patients < or = 50 years of age with early stage tumors. Our results fully validate the recommendations of the 1992 Maine Consensus Meeting.

Adult↗
PubMed1996

Treatment of posttransplant lymphocele with povidone-iodine sclerosis: long-term follow-up.

Percutaneous transcatheter sclerosis with iodate-povidone has been proposed as a treatment of posttransplant lymphocele. We treated 19 lymphoceles with iodate-povidone, 10 of them totally resolved and 6 promptly recurred. Three recurrences were treated conservatively and in 3 the treatment was repeated with success. Therefore, we have a low recurrence and retreatment rate. Our total resolution rate was 100%. Complications due to the treatment were rare. In the long term no patient has developed any renal or perirenal complication related to iodine sclerosis. We conclude that iodine sclerosis is a safe and effective treatment of posttransplant lymphocele. We think that surgical procedures must be reserved to collections adjacent to renal hilum or inaccessible for safe puncturing.

Follow-Up Studies↗
PubMed1996

Soluble adhesion molecules in renal transplantation.

Serum levels of sICAM-1 and sVCAM-1 adhesion molecules as well as TNF cytokine were measured in 50 kidney transplant recipients [14 patients with stable graft function, 18 patients with acute rejection, 10 patients with CsA toxicity, 6 patients with ATN, and 2 patients with cytomegalovirus (CMV) disease] during the first 3 postoperative weeks. All the patients studied showed, on the first posttransplant day, elevated serum levels of sICAM-1 (260 +/- 53 ng/mL). Interestingly, all the patients with good graft function presented thereafter a reduction of sICAM-1 serum levels close to the normal values (185.2 +/- 40 ng/mL). In contrast, the group of patients with acute allograft rejection showed significantly increased serum levels of sICAM-1 (371.5 +/- 86 ng/mL; p < 0.001), 3-4 days before diagnosis of acute rejection. Although sVCAM-1 levels were increased in both acute graft rejection (2263 +/- 106) and CsA toxicity (1650 +/- 315) patients, such increase was not significant among either group of patients when the group with CsA toxicity was compared with either ATN (1320 +/- 204) or stable renal function (1089 +/- 167). No statistical differences in the levels of TNF were demonstrated between the different groups of patients studied. Our findings demonstrate that quantitative determination of serum sICAM-1 may be of predictive clinical value in transplanted patients with acute renal allograft rejection.

Cyclosporine↗
PubMed1995

Secondary avascular necrosis after treatment for congenital dislocation of the hip.

We made a radiographic study of 104 unilateral congenital dislocations of the hip (CDH) that had an average age of 12 months (range 4-24), were treated with the same therapeutic protocol, and had an average six years follow-up (range 3-13). Radiographic changes were evident in the proximal femoral epiphysis in 57 hips (55%). In 7 (7%) the changes consisted of central osteoporosis with a cystic aspect, without metaphyseal or physeal changes, and had a normal end result without sequelae. This group was classified as type I. Fifty hips (48%) that were type II showed epiphyseal changes consisting of trabecular rarefaction with osteoporosis and irregular sclerosis, followed by a decrease of epiphyseal height and trabecular recovery. Forty-two hips (40%) were type IIA, with < 75% decrease in epiphyseal height with respect to the healthy side; five of these had a normal evolution, 35 had coxa magna and/or decrease of epiphyseal height, and only two cases had physeal lesion. In type IIB, hips, with > 75% decrease of epiphyseal height, 8 cases (8%) had a final physeal lesion.

Child↗
PubMed1995

Traumatic hip dislocation with incomplete reduction due to soft-tissue interposition in a 4-year-old boy.

The case of a traumatic dislocation of the left hip in a 4-year-old boy is presented. After an initial attempt at reduction under general anesthesia, a permanent deformity in the flexion of the hip remained, and there was radiographic evidence of a nonconcentric reduction. Computed tomography (CT) showed interposition in the posterior part of the joint. Under general anesthesia, the mobilization of the hip reduced the dislocation correctly, removing the necessity of open treatment. This case stresses the need for early diagnosis of this serious complication and closed reduction of the joint, avoiding the poor results of open and deferred treatments.

Accidental Falls↗