PubMed Health⌕ Search

Biomedical subjects

Jesús Pérez

Publications and source records attributed to Jesús Pérez.

7 recordsLinked to original sources
PubMed2006

A learning algorithm for adaptive canonical correlation analysis of several data sets.

Canonical correlation analysis (CCA) is a classical tool in statistical analysis to find the projections that maximize the correlation between two data sets. In this work we propose a generalization of CCA to several data sets, which is shown to be equivalent to the classical maximum variance (MAXVAR) generalization proposed by Kettenring. The reformulation of this generalization as a set of coupled least squares regression problems is exploited to develop a neural structure for CCA. In particular, the proposed CCA model is a two layer feedforward neural network with lateral connections in the output layer to achieve the simultaneous extraction of all the CCA eigenvectors through deflation. The CCA neural model is trained using a recursive least squares (RLS) algorithm. Finally, the convergence of the proposed learning rule is proved by means of stochastic approximation techniques and their performance is analyzed through simulations.

Algorithms↗
PubMed2005

Higher frequency of uncommon 1.5-2 Mb deletions found in familial cases of 22q11.2 deletion syndrome.

Familial 22q11.2 deletions have been reported as a 6%-28% of the total affected cases of 22q11.2 microdeletion syndrome (del22q11.2). Different deletion genotypes have been described for this disorder, with a predominant 3 Mb deletion present in 90% of the cases, a less common 1.5-2 Mb deletion in 8%, and atypical smaller deletions in 2%. We have studied 15 cases of del22q11.2 from 6 families (two of them three-generation families) that were previously diagnosed through FISH. We have sized the deleted region by allele genotyping of 12-16 polymorphic markers in all cases, and we have found three families affected with the 1.5-2 Mb deletion, two affected with the 3 Mb deletion, and one in which the deletion size could not be determined. This predominance of the smaller 1.5-2 Mb deletions in our familial cases differs from the minor frequency observed in sporadic cases of del22q11.2. This finding suggests that small deletions are more linked to familial inheritance than large ones, possibly due to psychosocial or biological factors associated with differences in the phenotype. Deletion sizing on routine diagnosis may help characterizing the inheritability of 22q11.2 microdeletion syndrome.

Abnormalities, Multiple↗
PubMed2004

Characterization of the immunoreactivity of anti-interferon alpha antibodies in myasthenia gravis patients. Epitope mapping.

Cytokines, such as interferons (IFN), underlie many immunological functions and are increasingly implicated in disease-related symptoms and pathology. In order to study the potential roles of IFN alpha and its antagonists in autoimmune phenomena, the sera from 89 patients (aged 15-95 years, 65 females) diagnosed as having myasthenia gravis (MG) (2 months to 34 years duration) were tested for the presence of natural anti-IFN alpha-2b auto-antibodies. Sera were screened for anti-IFN alpha-2b by a sandwich-type enzyme immunoassay system. Ten (11.2%) and 6 (6.7%) sera were identified that contained positive-competing and non-competing anti-IFN alpha-2b auto-antibodies, respectively. The MG sera were further analyzed by immunobloting against reduced IFN alpha-2b and for neutralizing anti-IFN alpha activity in an antiviral assay cells system. From tested EIA positive-competing sera, 5 were shown to be positive by immunoblot and 6 sera were found to contain neutralizing anti-IFN alpha-2b. Four of the 6 neutralizing anti-IFN alpha-2b sera came from patients with thymoma-associated MG. The sera were studied for linear epitope recognition on the IFN alpha-2b molecule by a solid phase binding assay, in which overlapping peptides homologous with the entire IFN alpha-2b sequence were separately synthesized on a nitrocellulose sheet. Peptides number 2 (residues 8-21), 3 (15-28), 6 (33-46), 10 (63-76), 15 (98-112), and 21 (141-154) were immunoreactive. Peptide 21 was apparently associated with antiviral activity, although peptide 21 has not been previously described as an immunogenic determinant on the IFN alpha-2b molecule. These results indicate that neutralizing anti-IFN alpha-2b is often present in MG, particularly in cases of thymoma-associated MG, and recognize a variety of epitopes on the IFN alpha-2b molecule, including those involved in its biological activity. Two groups of IFN epitopes were described associated with patient's age but not with diseases evolution.

Adult↗
PubMed2004

Intussusception in a preterm neonate; a very rare, major intestinal problem--systematic review of cases.

Intussusception is an extremely rare disorder in preterm infants and it is often misdiagnosed as necrotizing enterocolitis. We report a case of intussusception in a 30-day-old preterm infant of 26 weeks of gestational age and a birthweight of 610 g who was diagnosed via abdominal ultra sonography. A systematic review of the literature was performed and reports on 23 previous cases were found. The presence of recognizable causes of intussusception in preterms, such as Meckel's diverticulum, bowel polypus, etc. was very infrequent. Comorbidity before and after intussusception is heterogeneous and related to prematurity. The intussusception is predominantly located in the small bowel (91.6%)--ileal or jejunal. The condition is misdiagnosed as NEC and managed conservatively until clinical deterioration occurs. A definitive diagnosis is thus established during abdominal surgery, which is usually delayed an average of 9.5 days from the onset of symptoms. Our case illustrates the capability of abdominal ultrasonography to establish early diagnosis of intussusception in the premature newborn.

Diagnosis, Differential↗
PubMed2003

Effect of minimal enteral feeding on splanchnic uptake of leucine in the postabsorptive state in preterm infants.

We conducted a controlled, randomized trial to study the effect of minimal enteral feeding on leucine uptake by splanchnic tissues, as an indicator of maturation of these tissues, in preterm infants in the first week of life. Within a few hours after birth, while receiving only glucose, a primed constant infusion of [1-(13)C]-leucine was started and continued for 5 h via the nasogastric tube, whereas 5,5,5 D3-leucine was infused intravenously (for both tracers, priming dose 2 mg/kg, continuous infusion 2 mg/kg/h). Patients were thereafter randomized to receive solely parenteral nutrition (C), parenteral nutrition and 20 mL breast milk/kg/d (BM), or parenteral nutrition and 20 mL formula/kg/d (F). On d 7, the measurements were repeated, after discontinuing the oral intake for 5 h. Fourteen infants were included in group C, 12 in group BM, and 12 in group F. There was no difference in energy intake or nitrogen balance at any time. On d 1, plasma enrichment for the nasogastric tracer was lower than for the intravenous tracer for all three groups, both for leucine and for alpha-keto-isocaproic acid. On d 7, the enrichment for leucine and alpha-keto-isocaproic acid for the nasogastric tracer was lower than for the intravenous tracer for the groups BM and F (BM: 3.65 +/- 1.20 nasogastric versus 4.64 +/- 0.64 i.v.; F: 4.37 +/- 1.14 nasogastric versus 5.21 +/- 0.9 i.v.). In the control group, there was no difference between tracers. The lower plasma enrichment for the nasogastric tracer compared with the intravenous tracer suggests uptake of leucine by the splanchnic tissues. We conclude that minimal enteral feeding--even in low volumes of 20 mL/kg/d--increases the leucine uptake by the splanchnic tissue. We speculate that this reflects a higher protein synthesis of splanchnic tissues in the groups receiving enteral nutrition.

Carbon Isotopes↗
PubMed2002

[Community-acquired pneumonia: usefulness of clinical presentation in the selection of antibiotic treatment].

BACKGROUND: Our purpose was to assess the usefulness of a strategy based on the clinical presentation in order to choose antibiotics in patients with non-severe community-acquired pneumonia (CAP). PATIENTS AND METHOD: During one year, all patients admitted to the emergency department with a diagnosis of non-severe (Fine risk-classes I, II and III) CAP, were randomized and assigned into the following groups: GROUP 1: the clinical presentation was not taken into account and all patients were treated with levofloxacin; GROUP 2: patients with typical presentation were treated with amoxicillin and patients with atypical presentation were treated with clarithromycin. The following aspects were evaluated during the follow-up: presence of fever after 72 h of treatment, days of hospitalization and complications. RESULTS: The eventual population analyzed included 125 patients: 59 (47%) were assigned to Group 1 and 66 (53%) to Group 2. Patients assigned to Group 1 had a lower rate of fever after 72 h of treatment (7% vs 27%, p = 0.005); they were hospitalized for fewer days (4.8 vs 8.1 days, p = 0.01), and had less complications: changes in antibiotic treatment (10% vs 23% p = NS), admissions in ICU (0% vs 5%, p = NS), re-admissions in hospital (0% vs 5%, p = 0.05) and mortality (0% vs 2%, p = NS). CONCLUSIONS: A strategy of empiric treatment of non-severe CAP with levofloxacin as the antibiotic of choice is more useful than that of a treatment based on the clinical presentation.

Adult↗