Biomedical subjects

Jaime Sánchez

Publications and source records attributed to Jaime Sánchez.

5 recordsLinked to original sources

PubMed2006

Three-dimensional virtual environments for blind children.

Information technologies are increasingly helping to integrate and socially include people with visual disabilities. Computing technologies have contributed grandly to attain this goal through innovative techniques and applications. Virtual environments, I/O interfaces, and sound based applications altogether with usability and cognitive impact studies are some of the most used research designs for children with visual disabilities. This study presents the design and usability evaluation of three-dimensional (3D) interactive environments for children with visual disabilities. We introduce AudioChile and AudioVida, interactive virtual environments that can be navigated through 3D sound to enhance spatiality and immersion throughout the environments 3D sound is used to orientate, to avoid obstacles, and to identify the position of diverse personages and objects within the environment. Usability evaluation results indicated that sound can be fundamental for attention and motivation purposes during interaction.

Acoustic Stimulation↗

PubMed2003

[Hemolytic anemia due to ABO or Rh antibodies in recipients of solid organ transplants].

BACKGROUND AND OBJECTIVE: Hemolysis due to ABO or Rh unmatched transplants in solid organ recipients owes to the passage of lymphocytes with immunologic information. The development of antibodies and hemolysis is directly related to the amount of lymphocytes that goes with the transplanted organ. We present five cases of hemolytic anaemia, 2 by ABO and 3 by Rh systems. PATIENTS AND METHOD: From January 1991 to June 2001, 22 liver transplants ABO-unmatched, 236 renal transplants Rh-unmatched and 240 liver transplants Rh-unmatched were performed in our center. Both in donors and recipients, we performed an hematologic study with determination of indirect antiglobulin test (IAT). When IAT was positive, the antibody was determined through different methods. If hemolysis was suspected after transplantation, direct antiglobuline test (DAT) and antibody specifity were determined. RESULTS: Two liver transplants ABO-unmatched and three Rh-unmatched developed hemolysis. It was severe in all them and appeared between the 8th and 40th post-transplant day. Screening for irregular antibodies was negative in all pre-transplant patients. In donors, anti-D was recognized in two cases. Among post-transplant patients, DAT and IAT were positive in all them, anti-A was found in two, anti-D in two and anti-E in one case. All patients were treated with IV steroids. Four required transfusion with compatible packed red blood cells. CONCLUSION: Hemolysis in the context of a solid organ transplantation with minor unmatched ABO or Rh must alert us about the possibility of passage of donor lymphocytes.

ABO Blood-Group System↗

PubMed2003

Expression of nitrergic system and protein nitration in adult rat brains submitted to acute hypobaric hypoxia.

Changes in the nitric oxide (NO) system of the rat cerebral cortex were investigated by immunohistochemistry, immunoblotting, and NO synthase (NOS) activity assays in adult rats submitted for 30 min to hypoxia, in a hypobaric chamber at a simulated altitude of 38,000 ft (11000 m) (154.9 mm Hg). The cerebral cortex was studied after different survival times, 0 and 24 h, 5, 8, 15, and 30 days of reoxygenation. This situation led to morphological alterations in the large type I interneurons, as well as immunoreactive changes in the appearance and number of the small neurons (type II), both containing neuronal NOS (nNOS). Some of these small neurons showed immunoreactive cytoplasm and short processes; others, the more numerous during all reoxygenation periods, contained the immunoreactive product mainly related to a perinuclear ring. Ultrastructurally, these small neurons exhibited changes in nuclear structures as in the shape of the nuclear membrane, in the distribution of heterochromatin, and in the nucleolar morphology. The reaction product for nitrotyrosine, as a marker of protein nitration, showed modifications in distribution of the immunoreactive product. No expression was found for inducible NOS (iNOS). All these modifications were accompanied by increased nNOS and nitrotyrosine production as demonstrated by Western blotting and calcium-dependent activity, returning to control conditions after 30 days of reoxygenation, suggesting a reversible NO mechanism of action.

Animals↗

PubMedDate not supplied

[HORIZONTAL TRANSMISSION OF HBV INFECTION IN MIGRANTSFROM A HYPERENDEMIC AREA TO THEIR CONTACTS IN A LOW ENDEMICITY AREA IN PERU]

Migration of inhabitants from high endemicity to low endemicity areas, where the majority of population is susceptible, implies a risk of transmission. This factor suggested the study of the presence of HBV infection on migrants from Huanta and in their host communities in Lima.MATERIAL AND METHODS: Forty families from a human settlement in the District of San Juan de Lurigancho, Lima, were chosen at random. This sample included migrant families and people who had born in Lima.The members of these families were subjected to a survey to obtain demographic data and possible risk factor for HBV infection, and venous blood sample was obtained to determine HBV serological markers by ELIZA techniques.RESULTS: A total of 215 people were evaluated, 130 (60,5%) were female, and 85 (39,5%) were male. There were 9 (4,2%) HbsAg carriers; 4 (1,9%) of them were born in Huanta; the other 5 (2,3%) were born in Lima, and had never been to Huanta. They were under 20 years of age. No significant association was found between the presence of HbsAg and the use of injectables, blood transfusions, tatoos, previous surgery, dental extractions or sexual relations.CONCLUSION: The presence of HbsAg carrier on people born in Lima, with no "classical" risk factor for HBV infection, could be associated with carriers migrating from a hyperendemic HBV area, suggesting a mechanism of horizontal transmission.

Journal Article↗

PubMedDate not supplied

Proliferation measurement in breast cancer by two different methods.

BACKGROUND: Different studies show that proliferation measurement in breast cancer may have an independent prognostic value. In the present study, tumor proliferation in breast cancer was analyzed by two radically different methods according to the technique used (immunohistochemistry and flow cytometry), associated costs and necessary equipment. The aim was to evaluate which method discriminates better between tumors with high and low proliferation in relation to all other available clinical and biological parameters. MATERIALS AND METHODS: Two hundred and eighty breast cancers (231 ductal infiltrating, 30 lobular, 19 or less frequent varieties) were studied. The post-surgical staging was as follows: 164 pT1, 87 pT2, 7 pT3, the remaining 22 were multifocal, diffuse tumors. Axillary nodal invasion was found in 99 cases (35.4%). Proliferation was studied by means of flow cytometry (DNA index and S-phase) in fresh tumor tissue and immunohistochemistry (Ki67) in paraffin-embedded tissue. Furthermore, hormone receptor (estrogen receptor, ER; progesterone receptor, PR), c-erb-B2 and p53 expressions were studied using the same method. Finally, histological and nuclear grade, tumor size and axillary nodal invasion were also included as variables of the study. RESULTS: A DNA index >1 (aneuploidy) correlated significantly with histological grade 3 (p = 0.01), nuclear grade 3 (p < 0.0001), nodal invasion (p = 0.007), absence of ER (p = 0.006) and of PR (p = 0.002), c-erb-B2 expression (p = 0.008), p53 expression (p = 0.007) and tumor size (p = 0.01). An expression of Ki67 in 20% or more of tumor cell nuclei, on the other hand, correlated significantly with histological grade 3 (p < 0.0001), nuclear grade 3 (p < 0.0001), absence of ER (p < 0.0001) and of PR (p < 0.0001), c-erb-B2 expression (p < 0.0001), p53 expression (p < 0.0001) and tumor size (p = 0.0005), but not with nodal invasion. CONCLUSION: Although flow cytometry provides additional data (association with nodal invasion), the study of Ki67 expression emerges from this study as a simple, inexpensive and reliable method to study the proliferation rate of breast cancer.

Aneuploidy↗