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Biomedical subjects

S Gallego

Publications and source records attributed to S Gallego.

At least 19 recordsLinked to original sources
PubMed2006

Effect of spin-orbit interaction on a magnetic impurity in the vicinity of a surface.

We propose a new mechanism for surface-induced magnetic anisotropy to explain the thickness dependence of the Kondo resistivity of thin films of dilute magnetic alloys. The surface anisotropy energy, generated by spin-orbit coupling on the magnetic impurity itself, is an oscillating function of the distance d from the surface and decays as 1/d2. Numerical estimates based on simple models suggest that this mechanism, unlike its alternatives, gives rise to an effect of the desired order of magnitude.

Journal Article↗
PubMed2006

[Ecographic study of kidney size in children].

OBJECTIVE: The objective of this study is the determination of the normal kidney size in children analysing the variables that have a good correlation with it. With these correlations the normal kidney size can be established and a diagnose of possible diseases set. METHODS: The data was obtained through ecographies taken in 474 children between 0 and 18 years old that were under control for several reasons differently from the suspicion of a kidney disease. The information related to age, sex, weight, height and corporal surface was also taken. RESULTS: We studied 265 girls and 209 boys. No difference was obtained between the size of the girls and boys kidneys. The regression analysis of the left kidney shows correlations of 0.911 for the height, 0.896 for the corporal surface, 0.863 for the weight and 0.857 for the age; while the one of the right kidney shows correlations of 0.921 for the height, 0.902 for the corporal surface, 0.872 for the age and 0.871 for the weight. The determination coefficients were 0.83 for the left kidney and 0.85 for the right one. The multivariant analysis shows that for both kidneys the height and the age are variables statistically significant as well as the corporal surface for the left kidney. CONCLUSIONS: The size parameters measured in the kidneys show a statistically significance correlation with certain parameters of the growing. The maximum correlation appears for the height of the patient, which allows establishing regression equations with the kidney size and the height and therefore to detect any deviations from these regression curve.

Adolescent↗
PubMed2006

[The start of renal replacement therapy in a Spanish department].

BACKGROUND: Early nephrological referral and planned start of dialysis are associated with better prognosis after the beginning of renal replacement therapy (RRT). The aim of our study was to analyse patient clinical and analytic characteristics at the time of initiating dialysis and to evaluate if morbimortality was affected by planned start. PATIENTS AND METHODS: We performed a retrospective study of all patients commencing RRT in a Spanish Hospital of The National Health System over two years (2003-2004). A total of 117 patients (47 female and 70 male) were included. We carried out a retrospective analysis of the demographic characteristics, patients' clinical and analytic conditions at the time of starting dialysis and hospitalization days and mortality in six months after starting dialysis. Patients were classified as planned (P) or unplanned (NP), depending on whether the first dialysis was planned or an emergency. RESULTS: Sixty five patients (56.4%) started dialysis in a planned group while 52 (43.6%) were unplanned. In the former group, 83.1% of the patients had a vascular or peritoneal access available when starting RRT, whereas in the later group only the 3.8% had it. Planned dialysis initiation was associated with a high level of serum haemoglobin, haematocrit, calcium and albumin (p < 0.001), and a low level of serum urea, creatinine (p < 0.001) and phosphate (p < 0.05). More patients of the unplanned group were admitted at hospital at the initiation of dialysis (90.4% vs. 6.1%) and during the first 6 months (48% vs. 15.3%). The period of hospitalization was longer for the unplanned group (23.6 days vs 3 days) (p < 0.001). The 6-month-mortality was lower in the planned group (4.6% vs. 11.5%), whitout statistical difference. CONCLUSIONS: Planned dialysis initiation is associated with better clinical and metabolical conditions, greater probability of a vascular or peritoneal access availability and lower rate of hospitalization and mortality within 6 months after starting RRT

Adolescent↗
PubMed2005

Molecular evidence of HTLV-1 intrafamilial transmission in a non-endemic area in Argentina.

In the North of Argentina, an endemic area for HTLV-1, intrafamilial transmission of this virus has been observed. The HTLV-1 status in 13 family members of a seropositive blood donor from the central region of Argentina (non-endemic area) was investigated. According to serological and molecular assays, four members of this family (the blood donor, the husband, a son, and a daughter-in-law) proved to be HTLV-1 positive. LTR, tax, and env sequences from the provirus infecting the family members were identical. This strongly suggests the intrafamilial transmission of the virus. This study demonstrated intrafamilial transmission of HTLV-1 in a non-endemic area of Argentina.

Adult↗
PubMed2003

[Comparison between two 13C-urea breath tests for the diagnosis of Helicobacter pylori infection: isotope ratio mass spectrometer versus infrared spectrometer].

OBJECTIVES: To compare the accuracy of the breath test using the isotope ratio mass spectrometer (IRMS) versus the nondispersive isotope-selective infrared spectrometer (NDIRS) in the diagnosis of Helicobacter pylori infection. METHOD: Multicenter study in 4 Spanish hospitals. One group of dyspeptic patients who had not undergone prior eradication therapy and another group of patients with gastric ulcer or gastrointestinal bleeding due to gastroduodenal ulcer receiving H. pylori eradication therapy were included in the study. A reference standard based on histology and the rapid urease test was used. The breast test (TAU-KIT, Isomed S.L., Madrid, Spain) was performed with citric acid and 100 mg of 13C-urea. Samples of expired air were collected in tubes and bags for reading with the IRMS (ABCA, PDZ, Crewe, Manchester, England) and the NDIRS (UBiT-IR200, Otsuka Electronics, Co, Osaka, Japan), respectively. The endoscopist, pathologist and person responsible for reading the urease test and both breath tests were blinded to the results of the other diagnostic methods. RESULTS: Forty-one patients were included. The prevalence of H. pylori was 26%. No differences were found on comparing the mean values obtained with the IRMS and the NDIRS: 13 (standard deviation) (24) and 14 (25) delta units, respectively. The area under the ROC curve for the IRMS and the NDIRS was 0.96. The diagnostic accuracy for the best cut-off point with the IRMS and the NDIRS was, respectively: sensitivity (90 and 100%), specificity (96 and 89%), positive predictive value (90 and 77%), negative predictive value (96 and 100%), + likelihaod ratio (25 and 9.3) and (0.1 and 0). A close correlation was found between the values of the IRMS and those of the NDIRS (lineal regression equation, Y = 1.1 + 1.004. X; r = 0.97). CONCLUSION: Both the spectrometers used to evaluate the breath test, the IRMS and the NDIRS, offer a high degree of accuracy in the diagnosis of H. pylori infection.

Breath Tests↗
PubMed2003

Spinal cord compression due to tumoral idiopatic calcinosis.

STUDY DESIGN: A case of thoracic spinal cord compression due to tumoral calcinosis (TC) is reported. SETTING: Galiza, Spain. CASE REPORT: A 59-year-old man was admitted to our hospital with a 2-month history of gradual leg weakness and sensory deficit. The neurological examination revealed paraparesis with T12 sensory level. Magnetic resonance imaging (MRI) showed an extradural right posterolateral mass at T11-T12 level, resulting in a marked spinal cord compression. He underwent T11-T12 laminectomy and mass excision. Histological examination finally led to the diagnosis of TC. CONCLUSION: TC is an uncommon cause of mass lesions of the spine. Since there is no typical spine TC MRI appearance, the final diagnosis is done by histological studies. TC should be considered in differential diagnosis of spinal cord compression and constitutes a treatable cause of paraparesis.

Calcinosis↗
PubMed2003

Validation of the 13c-urea breath test for the initial diagnosis of helicobacter pylori infection and to confirm eradication after treatment.

OBJECTIVES: the breath test with 13C-urea (UBT) is a method widely used in Spain, but its diagnostic accuracy has not been evaluated in a clinical trial until now. Our objective was to validate the UBT (TAU-KIT) both as an initial diagnostic method for the detection of H. pylori infection and as a method to confirm eradication. METHODS: a multi-centre study in 7 Spanish hospitals was performed. A group of dyspeptic patients who had not previously received eradication treatment was included, and a second group of patients with gastric ulcer or upper gastrointestinal bleeding due to peptic ulcer was also included (eradication of H. pylori was confirmed 6 to 8 weeks after treatment completion with omeprazole, clarithromycin and amoxycillin). In both groups an endoscopy was performed with biopsies for histology and rapid urease test. Patients were considered infected if both tests yielded positive results, and not infected when both tests were negative. The UBT 13C-urea (TAU-KIT, Isomed S.L., Madrid, Spain) was performed with citric acid and 100 mg of 13C-urea. The pathologist and persons responsible for endoscopy, urease test and UBT were all unaware of the results from the other diagnostic methods. RESULTS: in the pre-treatment group (36 patients) the prevalence of H. pylori was 72%, the area under the ROC curve for the diagnosis of infection with the UBT was 0.99, and the best cut-off point was 5 units, with the following results: sensitivity= 96% (95% CI = 81-99%), specificity= 100% (69-100%), positive predictive value (PPV) = 100% (87-100%), negative predictive value (NPV) = 92% (59-100%), likelihood ratio (LR) + = infinity, and LR- = 0.04. In the post-treatment group (85 patients) the prevalence of H. pylori was 16%, the area under the ROC curve was 0.99, and the best cut point was 4.6, with the following results: sensitivity= 100% (77-100%), specificity = 97% (90-99%), PPV = 88% (62-98%), NPV = 100% (95-100%), LR+ = 35, and LR- = 0. CONCLUSION: UBT provides excellent accuracy both for the initial diagnosis of H. pylori infection and to confirm eradication after treatment.

Adult↗
PubMed2002

[Binaural cochlear implantation: general concept, surgical technique and electrophysiology].

Cochlear implant have been proven to be safe and cost-effective in deafened adults. Generally, a single cochlear implants is proposed providing monaural audition. Some teams have published interesting results in patients wearing two cochlear implants. The cost of the surgical procedure is greatly increased for bilateral implantation. In an attempt to provide patients with binaural hearing and a better chance to improve their capacity for frequency discrimination without an excessive increase in cost, we developed an new concept and design for binaural cochlear implants. The aim of the present study was to establish the surgical technique for binaural cochlear implantation with a single internal receptor-stimulator. We report descriptive data on surgical procedures performed in two cadavers and in two deafened adults. The special implant is composed of a single receptor-stimulator and two electrode arrays: a short one implanted into the ipsilateral ear and a long one in the contralateral ear. A specially designed tool for endoscopic facial lifting was used to create subcutaneous tunnels from the ipsilateral to the contralateral ear. Insertion into cochleas was unremarkable. Additional time for surgery (compared with mean operative time for routine adult surgery in our unit), and surgical details are discussed. Binaural cochlear implantation is feasible, easy and not very time consuming. Studies are in progress to determine patient benefit. Obtaining auditory brainstem evoked potentials electrically in patients with binaural cochlear implants is possible and provides an interesting mode for in vivo analysis of the long-term effect of profound/total deafness on neural transmission. In our patients, results have demonstrated that neural response properties in auditory pathways are negatively related to duration of deafness.

Adult↗
PubMed2000

[Neuroblastoma: biological markers, surgery, and clinical course].

INTRODUCTION: The treatment of neuroblastoma is basically chemotherapy, and surgery, in spite of advances, this kind of tumor is nowadays a surgical challenge. PURPOSE: The aim of this study was to evaluate the impact of our therapy in this kind of pediatric tumors. MATERIAL AND METHODS: 32 consecutive patients with abdominal neuroblastoma, aged between 1 month and 10 years old, median age 3 years old, observed from 1993 through 1997 have been studied. Several parameters: age, ferritin, deletion of the chromosome 1p36, chromosomic ploidy, LDH, N-myc gene amplification and enolase neuron specific were studied and were related with the histology by Joshi and the International Neuroblastoma Staging System (INSS) in order to know the prognosis. All the patients were treated by means of chemotherapy and surgery, and some cases with radiotherapy and bone marrow transplantation. RESULTS: Two patients presented the tumor in stage I (INSS) and three in stage II. All the patients had a total resection and they live free of disease. In the state III, two patients did not maintain the follow-up; five live with disease (two with QT without surgery yet, two local recurrences, and one metastasis), and four live free of disease. In the stage IV: five died, two live with disease (1 local recurrence and one metastasis), five live free of disease, and one did not maintain the follow-up. In the stage IV-S, the three patients live free of disease. The method of Kaplan-Meier at 5 years shows a mean of 49 months and a median of 60 months. CONCLUSIONS: 1. Of all the parameters studied, we consider the ones with biggest prognostic efficacy are, the age, the stage INSS, the histology Shimada and the N-myc amplification. 2. The total resection of the tumor keeps being essential for a more favourable prognostic.

Abdominal Neoplasms↗
PubMed1999

L-Type calcium channels in enterochromaffin cells from guinea pig and human duodenal crypts: an in situ study.

BACKGROUND & AIMS: This study has investigated stimulus-secretion coupling of enterochromaffin cells by studying the cellular location and function of voltage-gated Ca(2+) channels within small intestinal crypts. METHODS: Digital fluorescence imaging and electrochemical detection were used to measure intracellular Ca(2+) responses and serotonin (5-hydroxytryptamine [5-HT]) secretion in intact crypts isolated from guinea pig and human duodenum. RESULTS: In fluo-3-loaded crypts, electrical depolarization with high K(+) solution increased cytosolic free [Ca(2+)] only in single cells subsequently identified by immunocytochemistry as enterochromaffin cells. In guinea pig enterochromaffin cells, the L-type Ca(2+) channel agonist FPL 64176 (3 micromol/L) did not change resting intracellular [Ca(2+)] but potentiated the depolarization-evoked increase in [Ca(2+)] (298 +/- 72 nmol/L) by 19 +/- 3-fold. In the majority of human enterochromaffin cells, FPL 64176 alone increased resting [Ca(2+)] by 423 +/- 171 nmol/L. Secretion studies in guinea pig crypts showed that high K(+) and FPL 64176 caused a 12-fold increase in 5-HT release. Noradrenaline caused increases in both enterochromaffin cell [Ca(2+)] and 5-HT release. CONCLUSIONS: Using this approach, we have found that in duodenal crypts, enterochromaffin cells, but not other epithelial cells, contain L-type voltage-gated Ca(2+) channels involved in regulating 5-HT secretion. These data have implications for the pharmacological control of intestinal disorders involving enterochromaffin cell dysfunction.

Aniline Compounds↗
PubMed1999

Efficiency of indirect immunofluorescence assay as a confirmatory test for the diagnosis of human retrovirus infection (HIV-1 and HTLV-I/II) in different at risk populations

We compared the indirect immunofluorescence assay (IFA) with Western blot (Wb) as a confirmatory method to detect antibodies anti retrovirus (HIV-1 and HTLV-I/II). Positive and negative HIV-1 and HTLV-I/II serum samples from different risk populations were studied. Sensitivity, specificity, positive, negative predictive and kappa index values were assayed, to assess the IFA efficiency versus Wb. The following cell lines were used as a source of viral antigens: H9 ( HTLV-III b); MT-2 and MT-4 (persistently infected with HTLV-I) and MO-T (persistently infected with HTLV-II). Sensitivity and specificity rates for HIV-1 were 96.80% and 98.60% respectively, while predictive positive and negative values were 99.50% and 92.00% respectively. No differences were found in HIV IFA performance between the various populations studied. As for IFA HTLV system, the sensitivity and specificity values were 97.91% and 100% respectively with positive and negative predictive values of 100% and 97.92%. Moreover, the sensitivity of the IFA for HTLV-I/II proved to be higher when the samples were tested simultaneously against both antigens (HTLV-I-MT-2 and HTLV-II-MO-T). The overall IFA efficiency for HIV-1 and HTLV-I/II-MT-2 antibody detection probed to be very satisfactory with an excellent correlation with Wb (Kappa indexes 0. 93 and 0.98 respectively). These results confirmed that the IFA is a sensitive and specific alternative method for the confirmatory diagnosis of HIV-1 and HTLV-I/II infection in populations at different levels of risk to acquire the infection and suggest that IFA could be included in the serologic diagnostic algorithm.

Journal Article↗
PubMed1999

Prevalence of antibody to human T cell lymphotropic virus types 1/2 among aboriginal groups inhabiting northern Argentina and the Amazon region of Peru.

We carried out a seroepidemiologic survey to define the prevalence of human T cell lymphotropic virus types 1/2 (HTLV-1/2) infections among aboriginal populations from isolated regions of northern Argentina and the Amazon region of Peru. Antibodies against HTLV were measured with agglutination tests and confirmed with by an immunofluorescence assay (IFA) and Western blotting. Five (6.94%) of 72 samples from the Tobas Indians in Argentina were positive by the IFA; two samples were typed as HTLV-1 (2.78%), two as HTLV-2 (2.78%), and one (1.39%) could not be typed because it had similar antibody titers against both viruses. No positive samples were found among 84 Andinos Puneños and 47 Matacos Wichis Indians. Seroprevalences of 2.50% (1 of 40) and 1.43% (1 of 70) for HTLV-1 were observed among Wayku and San Francisco communities in the Amazon region of Peru, and seroprevalences of 4.54% (1 of 22) and 2.38% (1 of 42) for HTLV-2 were observed among Boca Colorada and Galilea communities. No serologic evidence of human immunodeficiency virus (HIV) infection was found among the Indians tested. These results indicated the presence of HTLV-1 and HTLV-2 in the indigenous populations of Argentina and Peru. Moreover, the lack of HIV infection indicates that the virus has probably not yet been introduced into these populations.

Argentina↗
PubMed1998

Correlation between electrical auditory brainstem response and perceptual thresholds in Digisonic cochlear implant users.

OBJECTIVES: To examine the relationships between psychophysical perceptions and the electrically evoked auditory brainstem responses (EABRs) in multichannel cochlear implant (CI) users and to determine the effectiveness of EABRs in electrode failure. DESIGN: A descriptive study reported the EABR characteristics while the different electrodes were activated. Characteristics of the EABR and of the perceptual measures served as compared variables in a correlational study. SETTING: The study was carried out in the audiology clinic of an otolaryngology department at a university hospital. PATIENTS: The subjects consisted of nine consecutively selected habitual Digisonic DX1OR multichannel CI users. Seven patients were postlinguistically deafened adult patients; two were congenitally deaf children. MAIN OUTCOME MEASURES: Ipsilateral recordings were performed using a previously published method. Morphology, latency, and amplitude measures of the EABR recordings were described, computed, and compared with the literature data for EABRs obtained while activating other types of CI and for acoustically evoked ABRs. Correlations between EABRs and behavioral perception thresholds were analyzed using the parametric Pearson's correlation test. RESULTS: EABRs allowed the authors to detect failure of no. 10 electrode integrity in one child. Perceptual threshold measures were found to be highly significantly related to the EABR threshold across subjects and electrode position (n = 31, r = 0.98; P < 0.001; linear regression equation: perceptual threshold = 1.06 EABR threshold + 0.76). The latencies and amplitudes were found to be similar to those described in the literature. CONCLUSIONS: EABRs may be used to estimate settings for the Digisonic DX10 CI even in a pediatric population, although they cannot entirely replace behavioral measurements, especially in children. The EABR can be employed for electrode dysfunction diagnosis. Further studies are needed to determine whether recordings of EABR quality could contribute to the evaluation of functional prognosis during the rehabilitation.

Adult↗
PubMed1997

Kinetics study of human retrovirus antigens expression in T lymphocytic cell lines by indirect immunofluorescence assay.

Indirect immunofluorescence assay (IFA) is a well-accepted assay for the confirmation of human retrovirus infection. Fluctuations in HIV-1 antigen expression in infected E-B2 cells depending on several factors have been reported. Cells kept in log phase expressed the highest levels of viral antigen. Thus, we studied the time kinetics of IFA positivity in MT-2 (HTLV-I), MO-T (HTLV-II), CEM, and H9 (HIV-1) cell lines. Uninfected T cell line, HT, was used as nonspecific control. Reference HTLV-I/II and HIV-1 serum panels from the Centers for Disease Control and Prevention (CDC) were tested by conventional IFA procedure on slides of each cell line made on different days. On the second day after subculture, HTLV-I strongly positive sera reacted on MT-2 and MO-T cells with a bright pericytoplasmic fluorescence pattern. Weakly positive sera showed a faint staining from the fifth day on, when all the sera showed the highest degree of fluorescence. With HIV-1 cell lines, sera predominantly reacted with a diffuse cytoplasmic pattern, although some sera showed a granular and pericytoplasmic capping staining. The highest degree of fluorescence was found at 3-5 days after subculture. We demonstrated that the sensitivity of the IFA for the detection of antibodies against human retroviruses depended on the day when the slides were assayed and on the serum antibody titer. The fifth day was the most appropriate for HTLV-I/II and HIV-1/H9 systems, whereas for HIV-1/CEM, the fourth day was better. Furthermore, the intensity of the immunofluorescence pattern differed with the antibody titers and the level of antigens expressed on the four cell lines studied. The IFA, improved in our laboratory, proved to be very sensitive, specific, and rapid and could be used as a supplementary/confirmatory assay for retrovirus infection.

Cell Line, Transformed↗
PubMed1997

[Value of auditory evoked potentials of the brain stem in patients with a Digisonic cochlear implant].

We report our techniques of electrically elicited Auditory Brainstem Responses (eABR) in Digisonic DX 10 cochlear implanted patients and summarize the theoretical interests of objectives measures in pre-, per- and post-operative periods of the cochlear implantation process. This report demonstrates the major interest of eABR during rehabilitation with a cochlear implant. EABR allowed us to detect the lack of device integrity in one electrode in one patient. The quality of electrically elicited responses can contribute to appreciate the electrophysiological responses during electrical stimulation. We found a very strong correlation between the objective thresholds (obtained by means of eABR) and subjective ones (obtained by means of behavioral methods); this is of major interest in the pediatric populations.

Acoustic Stimulation↗