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Biomedical subjects

J L Sánchez

Publications and source records attributed to J L Sánchez.

At least 19 recordsLinked to original sources
PubMed2006

An evolutionary Michigan recurrent fuzzy system for nuclei classification in cytological images using nuclear chromatin distribution.

OBJECTIVE: The objective of this research is to carry out the classification of cellular nuclei in cytological pleural fluid images. The article focuses on the feature extraction and classification processes. The extracted feature is a spatial measurement of the chromatin distribution in cellular nuclei. The designed classifiers are fuzzy classifiers that carry out supervised classification. The classifier system's inputs are data series that represent these texture measurements. METHODS AND MATERIAL: The classifier is built on a Recurrent Fuzzy System (RFS). An evolutionary algorithm inspired by the Michigan approach is used to find an optimal RFS to classify different patterns expressed as data series. RESULTS: The effectiveness of the proposed classifier system is compared with other existing classification methods and evaluated via Receiver Operating Characteristic (ROC) analysis. We have obtained RFS based classifiers that perform with sensitivity values between 82.26 and 93.55% and with specificity values between 80.65 and 90.32%. The behavior of the proposed chromatin measurement is also compared with other texture measurements. CONCLUSION: The RFS based classifiers were successfully applied to the proposed data series that represent the chromatin distribution in cellular nuclei. These fuzzy classifiers present the highest classification efficiency and the ROC analysis confirms their suitable behavior.

Algorithms↗
PubMed2005

Epidemiology of transfusion-transmitted infections among multi-transfused patients in seven hospitals in Peru.

BACKGROUND: Transfusion-transmitted infections (TTIs) constitute a major health problem worldwide where routine screening of blood or blood products is improperly done, and where non-medical injecting medications and/or drug use are prevalent. Prevalence and risk factors vary by geographic location and by the specific TTI (including HIV-1, HBV, HCV and HTLV-I). OBJECTIVE: To determine the prevalence and risk factors associated with TTIs among a sample of multi-transfused adult patients in Peru. STUDY DESIGN: A cross-sectional multi-center study was conducted across seven major hospitals in Peru from February 2003 to September 2004. Self-reported behavior information (medical procedures, number of sexual partners, and drug use history) was analyzed, along with a review of exposure history from hospital medical records. Prevalences were calculated by TTI for different exposures, along with unadjusted and adjusted odds ratios for infection risk. RESULTS: Overall, 192 (54.7%) of 351 multi-transfused patients were found infected with one or more TTIs. Number of transfusion units, years of transfusion history (6 or more), and number of treatment facilities (2 or more) were associated with HCV infection. Hemodialysis history was a common risk factor associated with HBV, HCV and HTLV-I infection. HIV infection was associated only with total number of transfusion units received. CONCLUSIONS: High prevalences of HBV and HCV infection were found among Peruvian multi-transfused patients and were associated with a past history and number of blood transfusions, as well as with past hemodialysis procedures. TTIs continue to represent a significant public health problem in Peru. Continued vigilant attention to blood safety procedures, including universal screening and health care provider education, is recommended.

Adolescent↗
PubMed2003

Sterol composition of gonad, muscle and digestive gland of Pecten maximus from Málaga (South Spain).

Sterol composition and content and their seasonal variations over 18 months were investigated in adductor muscle, digestive gland and gonads of Pecten maximus. Sterols were isolated by Silicagel 60 thin layer chromatography and identified by gas chromatography/mass spectrometry. Eleven sterols were identified, with cholesterol, brassicasterol, 24-methylenecholesterol and 22-trans-dehydrocholesterol being the principal components. The same sterols were found in all three tissues independent of season. The relative amounts of each sterol present in each tissue differed. Total sterol levels in gonad and muscle were higher than in digestive gland. Statistically significant differences (P<0.05) were found between the concentrations of each of the sterols isolated from the gonad or muscle and digestive gland. The seasonal variations in the sterol content of the gonad seem be related to the reproductive cycle, while the sterol content of the digestive gland appears to be linked to diet, mainly diatoms or dinoflagellates. The muscle sterol content showed minor changes throughout the year.

Animals↗
PubMed2002

Multiple sclerosis in the tropics: genetic association to STR's loci spanning the HLA and TNF.

Clear evidence has been presented correlating gene polymorphisms at 6p21.3-21.4 (containing HLA and TNF) and the predisposition to acquire multiple sclerosis (MS). In a previous study, we found that polymorphisms at HLA DQAI were associated with being or not being predisposed to MS in individuals inhabiting the tropics, where the prevalence of MS is significantly lower than in subtropical areas. Here, we tested the hypothesis that polymorphisms at D6S276, D6S265, D6S273 and D6S291 microsatellite loci are in strong linkage disequilibrium with a major genetic factor predisposing to MS. These microsatellites span the 6p21.3 region with intervals of 5 cM establishing particular landmarks for the HLA and TNF loci. Thirty-five MS patients and 35 controls, age, sex, social, ethnically and geographically matched healthy individuals, were studied. After testing the fit of gene frequencies to the normal distribution and performing the correlation for multiple comparisons, we found significant differences among the case and the control frequencies for the allele 202 belonging to the marker D6S276 (Pc=0.00455) and for the allele 114 belonging to the marker D6S265 (Pc=0.0084). For these two alleles at different loci, we found higher frequencies in the cases than in the controls. A nonsignificant p value was found in testing the existence of linkage disequilibrium among the studied loci in the cases and in the controls. In conclusion, the current study adds evidence to the established association among polymorphisms of genes located at 6p21.3-21.4 and MS. Furthermore, because of the distribution of the tested microsatellite loci, the more probable critical region could be correlated with the TNF neighborhood.

Adult↗
PubMed2001

Tools for acquisition, processing and knowledge-based diagnostic of the electroencephalogram and visual evoked potentials.

The objective of our research is to develop computer-based tools to automate the clinical evaluation of the electroencephalogram (EEG) and visual evoked potentials (VEP). This paper describes a set of solutions to support all the aspects regarding the standard procedures of the diagnosis in neurophysiology, including: (1) acquisition and real-time processing and compression of EEG and VEP signals, (2) real-time brain mapping of spectral powers, (3) classifier design, (4) automatic detection of morphologies through supervised neural networks. (5) signal analysis through fuzzy modelling, and (6) a knowledge based approach to classifier design.

Adolescent↗
PubMed2001

Medium-dose UVA1 phototherapy in localized scleroderma and its effect in CD34-positive dendritic cells.

BACKGROUND: UVA1 radiation seems to be effective in morphea. CD34+ dendritic cells are significantly decreased in lesional skin of morphea patients. OBJECTIVE: We evaluated the therapeutic effectiveness of medium-dose UVA1 phototherapy in localized scleroderma and its effect in the number of dermal CD34+ dendritic cells in skin biopsy specimens of these patients. METHOD: Patients were irradiated with UVA1 (30 J/cm(2)) 30 times. Dermal CD34+ dendritic cells were counted before and after therapy. RESULTS: There was clinical improvement after UVA1 irradiation. Dermal CD34+ dendritic cells significantly increased after UVA1 irradiation. CONCLUSION: Medium-dose UVA1 therapy is effective in the treatment of localized morphea. Effectiveness is associated with an increase in the number of CD34+ dendritic cells in the dermis.

Adult↗
PubMed2001

Clinical features of multiple sclerosis in a genetically homogeneous tropical population.

Individuals affected with multiple sclerosis (MS) from a genetically homogeneous Caucasian population in Antioquia, a tropical region of Colombia, were evaluated in order to observe the clinical behavior of the disease. The frequency of clinical manifestations in 65 patients with definite MS from Antioquia was compared with those reported from temperate regions. The most common manifestations were optic neuritis and motor symptoms with absence of cerebellar symptoms. This presentation is significantly different from the frequency distribution at onset in series from temperate regions. These differences suggest that environmental factors could modify the clinical expression of MS in this population.

Asia↗
PubMed2001

Asthma risk, cleaning activities and use of specific cleaning products among Spanish indoor cleaners.

OBJECTIVES: Recent studies have shown an excess risk of asthma for cleaners, but it is not clear which cleaning-related exposures induce or aggravate asthma. METHODS: Risk factors for asthma were studied among indoor cleaners participating in the Spanish part of the European Community Respiratory Health Survey in 1992. In 1998, 78 of the 91 subjects reporting cleaning-related jobs in 1992 were identified. Of these, 67 indoor cleaners were interviewed by telephone about their cleaning activities and their use of cleaning products in 1992. These data were related to asthma prevalence in 1992, and the cleaners were compared with a reference group of office workers. RESULTS: Asthma prevalence was 1.7 times higher [95% confidence interval (95% CI) 1.1-2.6] among the cleaners than among the referents, being highest among private home cleaners (3.3, 95% CI 1.9-5.8). The prevalence of housedust mite sensitization amounted to 28% for the home cleaners and was significantly (P<0.01) higher than for other indoor cleaners (3%), but similar to the corresponding prevalence of office workers (22%). More than half of the cleaners reported work-related respiratory symptoms. The asthma risk of the home cleaners was mainly associated with kitchen cleaning and furniture polishing, with the use of oven sprays and polishes. CONCLUSIONS: The asthma risk of Spanish cleaners is primarily related to the cleaning of private homes. This relationship may be explained by the use of sprays and other products in kitchen cleaning and furniture polishing.

Adult↗
PubMed2001

[Acute language disorder in elderly patients: ischemic or epileptic origin?].

Acute language disorder is highly suggestive of cerebrovascular disease, but when accompanied by behavioral disturbance, particularly in elderly patients, it may express a different etiology. Six women aged 71 to 84 years presented with a mild behavioral disturbance followed by a language disorder that included fluent dysphasia, paraphasia, dysnomia, perseveration, and impaired understanding of complex orders. They fully recovered within 24 h. MR-imaging, including diffusion-weighted sequences in five of them, showed no acute lesions. EEG showed epileptogenic waveforms in three cases and slow waves in the other three, in a location that included the left temporal region. These findings disappeared in subsequent controls. All of these tests were performed during the acute episode or up to 72 h after onset. No patient has presented a new episode so far. The high sensitivity of new neuroimaging techniques forces the search for non-vascular etiologies in those patients in which no structural lesions that could account for the symptoms can be demonstrated. EEG can be useful in the diagnosis of some of these stroke mimics. Acute language disorders accompanied by disturbed behavior in the elderly may reflect a partial seizure of the temporal lobe.

Aged↗
PubMed2000

Automatic analysis of signals with symbolic content.

This paper presents a set of methods for helping in the analysis of signals with particular features that admit a symbolic description. The methodology is based on a general discrete model for a symbolic processing subsystem, which is fuzzyfied by means of a fuzzy inference system. In this framework a number of design problems have been approached. The curse of dimensionality problem and the specification of adequate membership functions are the main ones. In addition, other strategies, which make the design process simpler and more robust, are introduced. Their goals are automating the production of the rule base of the fuzzy system and composing complex systems from simpler subsystems under symbolic constrains. These techniques are applied to the analysis of wakefulness episodes in the sleep EEG. In order to solve the practical difficulty of finding remarkable situations from the outputs of the symbolic subsystems an unsupervised adaptive learning technique (FART network) has been applied.

Artificial Intelligence↗
PubMed2000

Primary cutaneous B-cell lymphoma of the leg in a chronic lymphedematous extremity.

This is a case report of a woman who had chronic lymphedema on one leg and who developed a primary cutaneous large B-cell lymphoma of the leg at that site. She received radiotherapy and did not show any systemic involvement thereafter. Other neoplasms may appear in a clinical setting of chronic lymphedema, namely, lymphangiosarcoma (Stewart-Treves), melanoma, and metastatic carcinoma. There are four other reports in the English literature of cutaneous lymphoma arising in an extremity with chronic lymphedema.

Aged↗
PubMed2000

Mandibular melasma.

Melasma is an acquired symmetrical brown hypermelanosis of the face. Three clinical patterns are recognized, namely centrofacial, malar and mandibular. This study addresses the clinical and histopathological features of ten women with mandibular melasma to determine its relation to other types of melasma. The mean age of the patients was 52 years and the onset of the disease occurred at an average age of 44 years. Sunlight aggravated the pigmentation in all cases. Only one patient was receiving hormonal therapy. Histopathologically, all patients demonstrated severe sundamage and hyperpigmentation of the epidermis. Nine of them had melanophages or melanin in the papillary dermis. We conclude than mandibular melasma may be a clinicopathologic entity different to other types of melasma.

Adult↗
PubMed1999

Risk of asthma in the general Spanish population attributable to specific immunoresponse. Spanish Group of the European Community Respiratory Health Survey.

BACKGROUND: Individuals with asthma are more atopic than the general population, but few reports have quantified this association, i.e. the proportion of asthma in the community due to specific immunoresponse. We aimed to determine the population attributable risk of asthma in the community due to atopy, and the quantity and quality of specific immunoresponses to common aeroallergens involved. METHODS: We used data from a cross-sectional study in a random sample of the general Spanish population, 20-44 years old, from five areas. In all, 1816 participants were given a symptoms questionnaire, a methacholine challenge and were assessed for atopy. Bronchial responsiveness (BR) was defined as a > or =20% fall in forced expiratory volume in one second (FEV1) after methacholine. Asthma was defined as symptomatic bronchial responsiveness. Atopy was assessed by measuring serum specific IgE or skin tests for sensitivity to Alternaria, birch, cat, Cladosporium, Dermatophagoides pteronyssinus, olive, Parietaria, ragweed or timothy grass. RESULTS: Sensitivity to any of the individual allergens tested significantly increased the risk of being asthmatic, at least twofold compared to non-atopic individuals. The population attributable risk of atopy in explaining asthma is 41.97% (95% CI: 29.2-60.3) when adjusting for area of residence, age, sex, and smoking. In symptomatic individuals, atopy was an independent factor in producing an early measurable PD20 (methacholine dose producing 20% fall in FEV1), especially in those atopic to two or more aeroallergens, and irrespective of the particular aeroallergen. CONCLUSIONS: Specific immunoresponse is strongly associated with asthma, but positivity to single allergens (quality) and the number of positive immunoresponses (quantity) do not change the per se risk of asthma in atopic individuals.

Adult↗
PubMed1999

Tumid lupus erythematosus.

BACKGROUND: Tumid lupus erythematosus (TLE) is a subtype of discoid lupus erythematosus (DLE) whose clinical characteristics rarely have been described in the literature. OBJECTIVE: To describe the clinical, histopathologic, and other laboratory findings in tumid lupus erythematosus. METHODS: Clinical and laboratory findings were reviewed in four patients who had been diagnosed with tumid lupus erythematosus by conventional microscopy. The diagnoses were characterized by a superficial and deep perivascular infiltrate of lymphocytes and deposits of mucin in foci in the reticular dermis. RESULTS: All four patients were young women. Ages ranged from 16 to 39 years (mean 21 years). The lesions consisted of numerous erythematous papules and plaques, some with annular configuration situated in the face and neck, trunk, and upper extremities. All four patients had concurrent lesions of classic DLE, three of them had systemic lupus erythematosus (SLE). Direct immunofluorescence test results were negative in nonexposed lesional skin of two of the patients. CONCLUSION: The clinical findings of concurrent lesions of TLE and classic DLE in the same patient, the presence of lesions of TLE in patients with SLE, and the histologic findings demonstrate that TLE is a distinct manifestation of DLE, and as such, a cutaneous expression of SLE.

Adolescent↗
PubMed1999

Multiple sclerosis: association to HLA DQalpha in a tropical population.

Studies performed in subtropical populations have found significant association between the phenotype multiple sclerosis (MS) and the major histocompatibility complex (MHC). We present the results of a case-control study conducted on a tropical population (Antioquia, Colombia) in order to detect a possible association between MS and HLA DQalpha (HLA DQA1*) alleles. Forty chromosomes belonging to MS patients were compared to two sets of controls (40 and 910 chromosomes, respectively). The HLA DQA1*0101 and DQA1*0102 alleles were found in a significantly higher proportion among the cases than among the controls, whereas the HLA DQA1*0103 allele was found in a significantly lower proportion of the cases. These results suggest that the association of HLA DQA1*0101, DQA1*0102 and DQA1*0103 to the MS phenotype found in Caucasian subtropical populations remains in individuals with MS inhabiting the tropics. This finding could mean that the major genetic component associated to the MHC in subtropical populations is the same in the tropics.

Adult↗