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Biomedical subjects

M García

Publications and source records attributed to M García.

At least 73 records · Page 4Linked to original sources
PubMed2002

Preparation and thermoluminescence properties of aluminium oxide doped with europium.

There is little information concerning the use of rare earths as dopants of Al2O3. This paper presents the preparation method and the results of studying the thermoluminescence characteristics of Al2O3:Eu exposed to ultraviolet light. Phosphor powder was obtained by the evaporation method. Optimum dopant concentration was 10% at an evaporation temperature of 700 degrees C. The powder obtained was submitted to thermal treatments at high temperatures in order to stabilise the traps. Diffraction patterns showed amorphous powder up to 500 degrees C; as the temperature was raised crystalline phases of Al2O3 appeared. The photoluminescence spectrum induced by 250 nm UV light exhibited four well defined peaks characteristic of the Eu3+ ion. The glow curve exhibited two peaks at 180 and 350 degrees C. The sensitivity of Al2O3:Eu was 10 times lower than Al2O3:C. The thermoluminescence response was linear from 2.4 to 3000 microJ.cm(-2) of spectral irradiance, and the fading 2% in a month. From these results it can be concluded that Al2O3:Eu has potential as an UV dosemeter.

Aluminum Oxide↗
PubMed2002

Thermoluminescent response of ZrO2 + PTFE prepared in Mexico to 90Sr/90Y beta particles.

Results of studying the thermoluminescent response of undoped ZrO2 + PTFE pellets irradiated with 90Sr/90Y beta particles are presented. Previously, TL characteristics of ZrO2 films doped with rare earths were studied. Phosphor powder was obtained by evaporating a solution of zirconium nitrate in ethanol. In order to stabilise the traps in ZrO2 this phosphor was submitted to different thermal treatments. Optimal thermal treatment consisted in heating at 1100 degrees C for 24 h. With this powder. pressing at room temperature a mixture (2:1) of ZrO2 and polytetrafluoroethylene (PTFE), pellets of 5 mm diameter and 0.8 mm thickness were made. The glow curve of ZrO2 + PTFE pellets exhibited two peaks at 200 and 250 degrees C: its TL response as a function of beta particles dose was linear in the range from 2 to 60 Gy. Repeatability over 10 cycles was 1.8%. Fading at room temperature was 3.8% per month.

Beta Particles↗
PubMed2002

Pre-irradiation semi-intensive chemotherapy with carboplatin and cyclophosphamide in malignant glioma: a phase II study.

We undertook a phase II trial in 17 patients with malignant glioma and large measurable disease to assess response rate and survival with pre-irradiation chemotherapy, using higher doses than standard, trying to improve the outcome. Patients characteristics were: male/female 10/7, age 49 (range 23-59), median Karnofsky index 90% (range 70-100), glioblastoma multiforme/anaplastic astrocytoma 14/3. Treatment consisted of 2 cycles of carboplatin 200 mg/m(2) days 1-3 (or AUC x 8, total dose) plus cyclophosphamide 1000 mg/m(2) days 1-3. One partial response (6.5%) and two stabilizations (13.5%) were observed after pre-irradiation chemotherapy. Twelve out of 15 patients (80%) progressed after chemotherapy. Median survival time was 7.6 months and the survival at 1 year was 33%. Main toxicity was hematologic in the first cycle: neutropenia grade 4 in 100%; thrombocytopenia grade 4 in 73% and grade 3 in 27%; anemia grade 3 in 7%; in the second cycle: neutropenia and thrombocytopenia grade 4 in 100% and anemia grade 3 in 50%). No toxic death was related to treatment. This regimen showed limited activity in malignant glioma with large residual disease after surgery or biopsy.

Adult↗
PubMed2002

Interocular effect of intravitreal injection of 6-hydroxydopamine and dopamine on spinule formation in teleost retina.

Terminal dendrites of cone horizontal cells (HCs) in teleost retinas show numerous spine-like protrusions named spinules, which are invaginated into the cone pedicles during light-adaptation, but retracted during dark-adaptation. Somata of HC show nematosomes whose size decreases as the number of spinules increases. Mechanisms regulating these changes in nematosomes and spinules are only partially understood, being an area of controversy in retinal cell biology. It has been suggested that efferent fibres from the brain to the retina might be involved in the control of spinule formation. Moreover, we have reported that actin depolymerization has an interocular effect on spinule formation, which could be mediated by these fibres. In the present report, we show an interocular effect on spinule dynamics: the monocular intravitreal injection of dopamine (DA) and 6-hydroxydopamine (6-OHDA), two drugs that affect the spinule formation, produces the same effects in the contralateral, untreated eye as in the injected eye. Our results reinforce the idea of an interocular central control of this phenomenon of synaptic plasticity. Dopamine-dependent events in the retina appear to be necessary to forge the afferent signals eliciting this interocular effect.

Adrenergic Agents↗
PubMed2001

Chromosome studies of murine T-cell lymphoid leukemia and derived cell lines.

Several cell lines were previously established from a spontaneous murine T-cell leukemia (LB). The aim of this study was to analyze the G- and C-banded karyotypes of the parental LB tumor cells and the derived cell lines. A sensitive cell line (LBL) from which two sublines originated, as well as Vincristine (LBR-V160) and Doxorubicin (LBR-D160) resistant cell lines, were used. Our results showed that LB cells had a pseudo-diploid karyotype with 40 acrocentric chromosomes in which trisomy of chromosome 14 was the most relevant alteration. The sensitive cell line showed this alteration in all metaphases studied; no changes in karyotypes were observed in either subline, despite their dissimilar morphology and growth patterns. In contrast, both resistant lines displayed a more heterogeneous karyotype with no common markers, except for the finding that chromosome 5 was involved in a trisomy in LBR-V160 and in a translocation with chromosome 12 in LBR-D160. Taking into account that the mdr genes are located in chromosome 5, these results suggest a possible association between such alterations and the acquisition of drug resistance.

Animals↗
PubMed2001

Antifibrogenic effect in vivo of low doses of insulin-like growth factor-I in cirrhotic rats.

Insulin-like growth factor-I (IGF-I) is produced mainly in the liver and it induces beneficial effects on the nutritional status, the liver function and oxidative hepatic damage in cirrhotic rats. The aim of this work was to analyze the effect of IGF-I on mechanisms of fibrogenesis in cirrhotic rats. Liver cirrhosis was induced by CCl(4) inhalation and phenobarbital in Wistar rats. Ten days after stopping CCl(4) administration (day 0), rats received either IGF-I (2 microg/100 g bw/day) (CI+IGF) or saline (CI) subcutaneously during 14 days. Animals were sacrificed on day 15. As control groups were used: healthy rats (CO) and healthy rats treated with IGF-I (CO+IGF). Liver histopathology, hydroxyproline content, prolyl hydroxylase activity, collagen I and III mRNA expression and the evolution of transformed Ito cells into myofibroblasts were assessed. Among the two control groups (CO+IGF), no differences were found in hydroxyproline content and these levels were lower than those found in the two cirrhotic groups. Compared with untreated cirrhotic rats, the CI+IGF-I animals showed a significant reduction in hydroxyproline content, prolyl hydroxylase activity and collagen alpha 1(I) and alpha1(III) mRNA expression. A higher number of transformed Ito cells (alpha-actin +) was observed in untreated cirrhotic animals as compared to CO and CI+IGF groups. In summary, treatment with IGF-I reduced all of the studied parameters of fibrogenesis. In conclusion, low doses of IGF-I induce in vivo an antifibrogenic effect in cirrhotic rats.

Actins↗
PubMed2001

[Personality traits and burnout in family doctors].

OBJECTIVE: With this research we try to study personality traits that could be associated with high punctuation at burnout scales (Maslach Burnout Inventory) in primary care physicians. DESIGN: Observational, descriptive, transversal. STUDY SETTING: 93 primary care centres in Barcelona-city and the northern province's region: Vallès Oriental, Vallès Occidental, Maresme, Osona, Bages and Berguedà (centre sanitary region). METHOD: Individual or collective direct interview to 528 primary care physicians. Three questionnaires were administrated: a sociodemographic item one, the Maslach Burnout Inventory (MBI), and the Cattell personality test 16-PF. RESULTS: The 40% of the interviewed physicians had some burnout symptoms without any difference between sexes. 12.4% of these showed very high burnout levels. Those subjects with burnout criteria punctuated different at stability, tension and vigilance traits and anxiety dimension. CONCLUSION: Some personality traits like low stability, the tension and the anxiety are associated with high punctuation of burnout.

Burnout, Professional↗
PubMed2001

Chronic nervous-system effects of long-term occupational exposure to DDT.

Dichlorodiphenyltrichloroethane (DDT) is a compound with moderate toxicity that is judged to be safe for occupational use, although little is known about its long-term effects on the human nervous system. We investigated chronic nervous-system effects of long-term occupational exposure to DDT by comparing the neurobehavioural performance of retired malaria-control workers with a reference group of retired guards and drivers. DDT-exposed workers did worse on tests assessing various neurobehavioural functions than controls; performance significantly deteriorated with increasing years of DDT application. Our results could not be explained by exposure to cholinesterase-inhibiting pesticides or other potential confounding factors.

Aged↗
PubMed2001

Factors increasing the mortality rate for patients with ruptured abdominal aortic aneurysms.

The objective of this report was to analyze the current surgical results of operative treatment in patients suffering ruptured AAA (abdominal aortic aneurysms) and to define those independent predictive factors for mortality. During a period of 2 years, from January 1996 to December 1997, 144 patients operated on for ruptured AAA in 10 hospitals were included in a multicenter retrospective study. Among the collected variables concerning each patient, those with potential relation to surgical mortality were studied: gender, age, diabetes, hypertension, cardiopathy, pulmonary obstructive disease, preoperative renal dysfunction, symptomatic cerebrovascular disease, peripheral vascular disease, hematocrit on admission, preoperative hypotension < 80 mmHg, loss of consciousness, cardiac arrest, aortic aneurysm location (infrarenal versus non-infrarenal), iliac involvement, aneurysm size, type of rupture, left renal vein ligature, ligature of a patent inferior mesenteric artery, place of aortic cross-clamping, type of grafting, exclusion of both hypogastric arteries, venous technical complications, associated surgery, use of cell saver, intraoperative blood loss, and postoperative complications (renal failure, sepsis, coagulopathy, cardiac complications, pulmonary complications, colon ischemia, prosthetic graft complications, and need for reoperation). Those variables with statistical significance in the univariate analysis were introduced into a multivariate logistic regression model to determine the independent predictors of death. From our results we concluded that surgery for ruptured abdominal aortic aneurysms continues to have an excessively high mortality rate. Even though some preoperative variables could be identified as predictors of mortality, an absolute mortality risk has not yet been determined and the decision to negate surgery should be individualized rather than taken on that basis only. Early diagnosis and treatment of symptomatic aneurysms would improve mortality figures and selective screening should be contemplated.

Age Factors↗
PubMed2001

[Morphological changes in adenotonsillar tissue as early manifestation of asymptomatic HIV patient].

The HIV virus induces in the host several changes in your immunological system, which heads to the AIDS. We report two cases diagnosed by pathological studies after adenotonsilectomy for adenotonsilar hypertrophy. The diagnosis of HIV patients is suspected by epidemiologic (risk groups) or clinical features (opportunist diseases). But, it exists a early diagnosis, the histological findings in the extranodal lymphoid tissues, unusual on the literature. These phenomenons re-enforce the contamination way by means of the superior aerodigestive tract mucosis.

Adenoidectomy↗
PubMed2001

[Usefulness of 201T1 gammagraphy in the diagnosis of carcinoma of the larynx].

For the evaluation of a patient with a laryngeal tumor we need the clinical exam and other exams as the CT scan or MRI. Those studies have a sensitivity of less than 80%. For that reason in the last years there has been a development of new techniques trying to increase the accuracy. The 201Tl SPECT is one of them although it was developed for cardiological purposes. We present our experience in 46 patients with laryngeal tumor in whom we did a 201Tl SPECT as part of the extension study. The sensitivity of the study was 81.6% in the diagnosis of the primary tumor and 46.1% for the neck adenopathies. The 201Tl SPECT can be a good method for the evaluation and detection of recurrences in patients with pharyngo-laryngeal tumor.

Aged↗
PubMed2001

[Shock secondary to extrinsic compression of the right atrium by postoperative mediastinal hematoma. Pseudotumor echocardiography image in right atrium].

We present the case of a 64 year-old patient in whom an aortic Saint Jude prosthesis, a Cosgrove's mitral annulus and triple coronary artery by-pass graft were implanted, and who presented with shock related to extrinsic compression of the right atrium by a mediastinal hematoma within the first postoperative month. Transthoracic echocardiogram showed a right atrial < >, hampering right atrium drainage. The extrapericardial location of the hematoma is of note and was diagnosed with the aid of thoracic computerized tomography. We present the case of a 64 year-old patient in whom an aortic Saint Jude prosthesis, a Cosgrove's mitral annulus and triple coronary artery by-pass graft were implanted, and who presented with shock related to extrinsic compression of the right atrium by a mediastinal hematoma within the first postoperative month. Transthoracic echocardiogram showed a right atrial < >, hampering right atrium drainage. The extrapericardial location of the hematoma is of note and was diagnosed with the aid of thoracic computerized tomography.

Heart Atria↗
PubMed2001

Insulin-like growth factor-I restores the reduced somatostatinergic tone controlling growth hormone secretion in cirrhotic rats.

BACKGROUND/AIMS: An altered growth hormone/insulin-like growth factor-I (GH/IGF-I) axis occurs in advanced liver cirrhosis, characterised by diminished serum levels of IGF-I and increased concentrations of GH. Under normal conditions, GH release is mediated by somatostatin (SS) inhibition. However, the influence of SS on GH release in cirrhosis is not well known. IGF-I supplementation has beneficial effects in experimental cirrhosis, and - under physiological conditions - IGF-I increases SS, inhibiting GH. The aims of this work were to study SS tone in cirrhotic animals and to evaluate whether IGF-I treatment influences SS tone, controlling GH secretion in cirrhosis. METHODS: We studied the influence of SS on GH secretion by assessing GH response to pyridostigmine (PD) in cirrhotic rats treated and untreated with IGF-I. Liver cirrhosis was induced with CCl4-inhalation for 11 weeks in male Wistar rats. The animals were randomly divided into two groups: CI+IGF (n=12), which received IGF-I treatment for 12 days (2 microg/100 g body wt-1 x d-1) and CI (n=12), which received saline. Healthy controls (CO, n=12) were studied at the same time. On day 13, animals from each group were subdivided into two groups (n=6) in order to explore the effect of a PD intrajugular bolus (10 microg x 100 gbw-1) on serum GH levels (at 0,10,20,30 and 60 min), which were assessed by RIA. RESULTS: PD bolus did not exert any effect on GH serum levels in the CI group, suggesting a low SS tone in cirrhotic rats. However, PD induced an increase in GH levels into CO and CI+IGF groups. In conclusion, as occurs under normal conditions, the cholinergic system is a significant modulator of GH secretion in experimental liver cirrhosis. CONCLUSION: Cirrhotic rats have a reduced somatostatinergic tone which can be restored by IGF-I supplementation, suggesting that somatostatin is the main factor involved in the feed-back regulation between GH and IGF-I in cirrhosis.

Administration, Inhalation↗
PubMed2001

Adult precursor B-ALL with BCR/ABL gene rearrangements displays a unique immunophenotype based on the pattern of CD10, CD34, CD13 and CD38 expresssion.

The Philadelphia chromosome (Ph+) reflects a balanced reciprocal translocation between the long arms of chromosomes 9 and 22 [t(9;22)(q34;q11.2] involving the BCR and ABL genes. At present, detection of BCR/ABL gene rearrangements is mandatory in precursor-B-ALL patients at diagnosis for prognostic stratification and treatment decision. In spite of the clinical impact, no screening method, displaying a high sensitive and specificity, is available for the identification of BCR/ABL+ precursor-B-ALL cases. The aim of the present study was to explore the immunophenotypic characteristics of precursor B-ALL cases displaying BCR/ABL gene rearrangements using multiple stainings analyzed by quantitative flow cytometry in order to rapidly (<1 h) identify unique phenotypes associated with this translocation. From the 82 precursor-B-ALL cases included in the study 12 displayed BCR/ABL gene rearragements, all corresponding to adult patients, four of which also displayed DNA aneuploidy. Our results show that BCR/ABL+ precursor B-ALL cases constantly displayed a homogeneous expression of CD10 and CD34 but low and relatively heterogeneous CD38 expression, together with an aberrant reactivity for CD13. In contrast, this unique phenotype was only detected in three out of 70 BCR/ABL cases. Therefore, the combined use of staining patterns for CD34, CD38 and CD13 expression within CD10-positive blast cells is highly suggestive of BCR/ABL gene rearrangements in adults with precursor B-ALL.

Adult↗