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Biomedical subjects

G Prieto

Publications and source records attributed to G Prieto.

At least 19 recordsLinked to original sources
PubMed2006

Size and stability of liposomes: a possible role of hydration and osmotic forces.

Dynamic light scattering and electrophoretic mobility measurements have been used to characterize the size, size distribution and zeta potentials (zeta-potentials) of egg yolk phosphatidylcholine (EYPC) liposomes in the presence of monovalent ions ( Na(+) and K(+)). To study the stability of liposomes the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory has been extended by introducing the hydrated radius of the adsorbed ions onto the liposome surfaces. The decrease of liposome size is explained on the basis of the membrane impermeability to some ions which generate osmotic forces, which leads to evacuate water from liposome inside.

Computer Simulation↗
PubMed2006

Non stenotic food impaction due to eosinophilic esophagitis: a potential surgical emergency.

AIM: Eosinophilic esophagitis (EoE) is an emergent condition in which a mucosal infiltrate of > 20 eosinophils per high power microscopic field is accompanied by motor disturbances that may cause food impaction in the absence of esophageal stricture. We report a series of such cases to point out the potential involvement of pediatric surgeons in diagnosis and treatment. Furthermore, data on the motor function of the esophagus investigated manometrically is included. MATERIAL AND METHODS: Thirteen patients with EoE were referred to our emergency room for acute food bolus impaction. Their median age at diagnosis was 12 years (range 7.6-14.4). History of allergy, endoscopy with biopsy and esophageal function (24-h combined ambulatory manometry with simultaneous pH-metry) were investigated. RESULTS: In 7 patients emergency endoscopic extraction of the impacted bolus was necessary. Allergic tests were positive in eight patients. The pH probe showed gastroesophageal reflux in two cases. Upon endoscopy, typical features of EoE (esophageal trachealization and whitish papular exudates) were found. Ambulatory 24-h manometry revealed abnormal motility of the distal esophagus with strikingly high amplitudes (> 150 mmHg) and long duration (> 7 sec) of the waves, particularly during the night. Six patients responded rapidly to steroids and/or antiallergic treatment. The remaining patients had a good outcome with dietary treatment alone. CONCLUSIONS: EoE is an emergent condition that may involve the pediatric surgeon in both the diagnosis and treatment. Typical endoscopic findings and biopsy are required for proper diagnosis. Ambulatory manometry reveals a marked propulsive dysfunction that explains impaction. This dysfunction is reversible, since the symptoms usually disappear with steroids or antiallergic treatment.

Adolescent↗
PubMed2005

Intestinal transplantation in children: differences between isolated intestinal and composite grafts.

The results of the isolated intestinal grafts were compared with those of composite grafts (intestinal graft + liver) in a series of 18 transplantations performed in 17 children; 5 isolated intestinal grafts, 12 hepatointestinal grafts, and 1 multivisceral graft. Causes of intestinal failure were short bowel syndrome (n = 13), motility disorders (n = 2) and congenital epithelial disorders (n = 2). Transplantation was indicated due to end-stage liver disease (n = 14), loss of venous access (n = 2), untreatable diarrhea (n = 1) and high morbidity associated with a poor quality of life (n = 1). Six children, all with a composite graft, died after transplantation due to lymphoma (n = 2), sepsis (n = 1); intraabdominal bleeding (n = 1); pneumonia (n = 1); and overwhelming adenoviral infection (n = 1). Digestive autonomy was achieved in 16 of 18 grafts, the 11 surviving children are free of parenteral nutrition with a reasonably good quality of life. In conclusion, intestinal transplantation is a viable therapeutic alternative for children with permanent intestinal failure. The results of transplantation with an isolated intestine are clearly better that those with a composite graft.

Adolescent↗
PubMed2004

A nonparametric approach to calculate critical micelle concentrations: the local polynomial regression method.

The application of a statistical method, the local polynomial regression method, (LPRM), based on a nonparametric estimation of the regression function to determine the critical micelle concentration (cmc) is presented. The method is extremely flexible because it does not impose any parametric model on the subjacent structure of the data but rather allows the data to speak for themselves. Good concordance of cmc values with those obtained by other methods was found for systems in which the variation of a measured physical property with concentration showed an abrupt change. When this variation was slow, discrepancies between the values obtained by LPRM and others methods were found.

Algorithms↗
PubMed2004

[Results of an intestinal transplantation program in Spain. Five years later].

BACKGROUND: More than two thirds of all intestinal transplantations (ITx) performed around the world correspondent to recipients younger than 18. OBJECTIVE: To analyze our 5-year experience in pediatric ITx. PATIENTS: We assessed the outcome of the 19 children included in list out of 41 patients considered for ITx from 1997. The main cause of intestinal failure was short bowel syndrome (14) followed by intestinal motility disorders (3) and congenit disorders of intestinal epithelium (CDIE) (2). The median of age, at the moment of including in the list, was 0.9 years (range 0.4-17) and median of weight was 6.4kg (range 0.4-29.3). Ten children were included for liver and small bowel transplantation (LSBTx), 7 to isolated small bowel (SBTx), and 2 for multivisceral transplantation (MVTx). Indications for SBx were hepatic fibrosis/cirrhosis (10), hepatic fibrosis in evolution (5) (to avoid later LSBTx), intractable diarrhoea (1), recurrent line infections (1), lost of central vein access (1), and bad quality of life in one. RESULTS: Five children died in the waiting list, after a median time of 325 days (range 19-581). Seven remain in the waiting list (median 139 days, range 30-778). In 3 of these the indication changed from SBTx to LSBTx because of progression to end stage liver disease. Six children recieved seven grafts (1 MVTx, 4 LSBTx, 2 SBx) after a median time in the waiting list of 352 days (range 66-732). Six out of seven grafts achieved normal function and all survivals reached full digestive autonomy after Tx. We had to rejection episodes, one with good response to medical treatment and one that required removal of intestinal allograft and later LSBTx. Two children died 1 because of problem not related to the procedure (hemorrage following liver biopsy) and one girl died 29 months after transplant due to post-transplantation lymphoproliferative disease. CONCLUSIONS: ITx is a realistic alternative in our country for children with intestinal failure. The main problems are immunologic (rejection, lynphoproliferative and disease) Shortage of small weight donors is a dramatic limitation that prompts the discussion of surgical alternatives.

Adolescent↗
PubMed2003

Th1 response in BALB/c mice immunized with Dirofilaria immitis soluble antigens: a possible role for Wolbachia?

The immune response to filarial infection has been shown to be of both the Th1 and Th2 types. Studies aimed at developing immunization strategies against Dirofilaria immitis infection in dogs have shown that protection against larval challenge is of the Th2 type and that several proteins are recognized by immunized or infected animals. The bacterial endosymbiont Wolbachia, harbored by many filarial species including D. immitis, has recently been shown to interact with the host immune system. Specific antibodies to the Wolbachia recombinant surface protein (WSPr) have been observed in cats infected with D. immitis. In this work the authors have determined cytokine production and antibody response in BALB/c mice inoculated with soluble antigens from third stage larvae or from adult worms of D. immitis. Inoculated mice first produced IFN-gamma followed by a peak in IL-4. Specific antibodies to the Wolbachia protein WSPr were exclusively IgG2a, while antibodies against peptides derived from antigens of D. immitis were in the IgG1 and IgE subclasses. The cytokine response is thus similar to that reported for other filarial infection, where Th1 response shifts towards Th2. Antibody response indicates that Wolbachia may induce preferentially a Th1 response during filarial infection, while nematode antigens may be involved in Th2 response. There is thus an overall agreement with current opinions on the role of bacterial versus nematode molecules in driving the response towards the different directions.

Animals↗
PubMed2003

Pediatric intestinal transplantation.

AIM: Analyze the results of a paediatric intestinal transplantation (IT) program in Spain. PATIENTS: During an 5-year period, 18 children were included as candidates for IT. The causes for intestinal failure (IF) were short bowel syndrome (n=13), motility disorders (n=3), and congenital epithelial disorders (n=2). Nine children were admitted for a combined liver-small bowel transplant (LSBT), seven for an isolated intestinal transplantation (IIT) and two for a multivisceral transplantation (MVT). In three of the candidates for IIT the indication had to be changed to LSBT because of progression of the liver damage. RESULTS: Eight candidates are on the waiting list: four for LSBT, two for IIT, and two for MVT. Four children died before transplantation. All were children under 1 year and candidates for LSBT. One child died during an attempted MVT. Five children underwent transplantation. Grafts were IIT in two and LSBT in three. Of these children, two are on a normal diet (respective follow-up times: 40 and 18 months), two died, both with functioning liver and intestinal grafts (hemorrage after liver biopsy and lymphoproliferative disease), and one developed an untreatable rejection that lead to loss of the intestinal graft; currently, she is on the waiting list for LSBT. CONCLUSIONS: The morbidity and mortality of IT are high, but it is the only possible treatment for children in IF who cannot be adequately managed with parenteral nutrition. A severe problem is the the scarcity of suitable donors for the very low weight children who are candidates for LSBT.

Adolescent↗
PubMed2003

Immunoglobulin G antibodies against the endosymbionts of filarial nematodes (Wolbachia) in patients with pulmonary dirofilariasis.

The dog parasite Dirofilaria immitis can infect humans. Patients with pulmonary dirofilariasis were tested for immunoglobulin G (IgG) antibodies against the surface protein of Wolbachia, the bacterial endosymbiont of D. immitis. These patients showed significantly higher IgG titers than healthy individuals from areas in which D. immitis was endemic as well as areas in which it was not endemic. Titration of anti-Wolbachia surface protein IgG could become useful for diagnostic applications.

Animals↗
PubMed2003

[Activity of a pediatric intestinal transplantation program in Spain].

AIM: To analyze the outcome of children with intestinal failure (IF) included as candidates for intestinal transplantation (IT). Patients, Eight out of 23 children with IF assessed since July 1997 met criteria for IT and were included on the waiting list. The causes of IT were Short Bowel Syndrome (SBS) in 6 and Microvillus Inclusion Disease (MID) in 2. The indication of IT were end stage liver disease (ESLD) in 5 (related to total parenteral nutrition administration, TPN), progressive hepatic fibrosis in 2 and loss of venous access in 1. The patients with ESLD were included for combined liver-small bowel transplantation (LSBT) and the remaining for isolated intestinal transplantation (IIT). RESULTS: Two children died waiting for LSBT, 4 patients are on the waiting list, 2 for LSBT and 2 for IIT (length of stay: 4-11 months). Two children were transplanted, one with IIT in a 2.5 years old boy with MID, and one with LSBT in a 22 months girl with SBS and ESLD. Both patients recovered intestinal function after transplantation and are a live (follow-up of 19 and 10 months respectively). The LSBT's patient is under treatment for postransplant lymphoproliferative disease (PTLD). CONCLUSIONS: The lack of suitable donors for the small children candidate to IT explains the long period of stay on the waiting list and the high pretransplant mortality. Two strategies are possible; early referral of children with IF to a transplant center and surgical techniques like ex vivi-hepatic reductions of the LSB graft.

Child↗
PubMed2002

Feline dirofilariosis: antibody response to antigenic fractions containing specific 20 to 30 kDa polypeptides from the adult Dirofilaria immitis somatic antigen.

Fractions from the adult somatic antigen (SA) Dirofilaria immitis complex, containing polypeptides from 20 to 30kDa, previously identified as molecular markers of feline dirofilariosis are isolated by sequential application of gel filtration and anion exchange chromatography. Indirect enzyme-linked immunosorbent assays, employing these fractions (20-26kDa/ELISAF1 and 30kDa/ELISAF7) show multivalent diagnostic capacities: they were able to detect pre-patent infections 2 months after infection, infections in clinical phase, and the fall of antibodies after the worms were removed from the heart, or the application of a ivermectin treatment. The results obtained by the two tests correlated well, in spite of the fact that ELISAF1 was most useful to detect antibodies in sera from cats in the clinical phase, while ELISAF7 has more sensitivity for the early detection of the infections. Both ELISAs were useful in the detection of the decrease of antibodies after the worms were removed by surgery or pharmacological treatment.

Animals↗
PubMed2001

Secondary structure of prothymosin alpha evidenced for conformational transitions induced by changes in temperature and concentration of n-dodecyltrimethylammonium bromide.

Conformational changes of prothymosin alpha (ProTalpha) induced by changes in temperature and concentration of the denaturant n-dodecyltrimethylammonium bromide (C12TAB) were studied by difference spectroscopy. The conformational transition of ProTalpha by C12TAB was followed as a function of denaturant concentration by absorbance measurements at 230 nm and the data were analyzed to obtain the Gibbs energy of the transition in water (deltaG0(w)) and in a hydrophobic environment (deltaG0(hc)) for saturated protein-surfactant complexes. The value of deltaG0(w) was 6.38 kJ mol(-1) and that for deltaG0(hc), which is not affected by temperature, was -18.62 kJ mol(-1). Changes of absorbance at 230 nm of ProTalpha with temperature can be assumed to resemble a transition in the secondary structure. The parameters characterizing the thermodynamics of unfolding, melting temperature (Tm), enthalpy (deltaHm), entropy (deltaSm) and heat capacity (deltaCp) were determined. The values obtained for Tm, deltaHm, and deltaSm are smaller that those found for other globular proteins; deltaCp was found to be much smaller. These results suggest that ProTalpha exhibits some type of secondary structure under these conditions (10 mM glycine buffer, pH 2.4).

Animals↗
PubMed2001

Acute food bolus impaction without stricture in children with gastroesophageal reflux.

BACKGROUND/PURPOSE: This report identifies a group of children in whom severe acute food bolus impaction (AFBI) was the leading symptom of gastroesophageal reflux (GER) in the absence of stricture. METHODS: The esophageal structure and function of 8 patients treated for AFBI requiring endoscopic removal of alimentary foreign bodies in 6 of them (up to 4 times in 1 case) were investigated by barium meal, esophagoscopy-biopsy, pH-metering, pull-through stationary manometry, and 24-hour ambulatory manometry. The results were compared with those in a group of age-matched regular refluxers (n = 14) without AFBI. RESULTS: Six boys and 2 girls aged 108 +/- 59 months had impaction. Six children had symptoms of GER like vomiting during infancy, heartburn, or respiratory tract disease. Barium swallow ruled out stenosis in all patients and showed small hiatal hernias in 3. All had endoscopic and histologic esophagitis (moderate to severe in 6), and one had Schatzki ring. All but one (who had 8.45 mm Hg) had normal lower esophageal sphincter pressure (16.2 +/- 4.7 mm Hg, mean +/- SD), and all showed normal sphincteric relaxation. Esophageal body motility was not significantly different from that in regular refluxers except in 6 children in whom energetic distal peristalsis after reflux episodes could be seen particularly during the night. Three of them had amazingly powerful distal waves during the day and even stronger, simultaneous, wide and bizarre-shaped waves during sleep. Symptoms improved in all cases after antireflux medication. Four patients were cured after antireflux surgery. CONCLUSIONS: AFBI is a dramatic but practically unheard of symptom of GER in children. It should be differentiated from dysphagia and reveals motor dysfunction, sometimes severe, of the esophageal body in the absence of sphincteric obstruction. Antireflux medication or surgery were uniformly successful in our patients.

Acute Disease↗
PubMed2001

Esophageal motor dysfunction persists in children after surgical cure of reflux: an ambulatory manometric study.

BACKGROUND/PURPOSE: Esophageal dysmotility shown by perfusion manometry in children with gastroesophageal reflux can be primary or acquired. This study examines by combined ambulatory pH-metry and manometry the nature of motor dysfunction and whether it improves after surgical cure of reflux. METHODS: Sixteen refluxing children aged 131 +/- 54 months were studied by combined ambulatory pH-metry and manometry before and more than 6 months after successful fundoplication. pH-metric and manometric variables were compared at both time end-points by paired statistical tests accepting a significance level of P less than.05. RESULTS: Operation cured all patients clinically and pH-metrically, but, in spite of this, only the frequency of motor sequences decreased significantly after the operation from 1 (0.45) to 0.8 (0.6) waves per minute (median [interquartile range]). Wave amplitude and duration were similar in both conditions; the proportion of peristaltic waves was normal and did not change before and after the operation (79.5% [17.25] v 81.4% [21.5]; not significant), whereas the proportions of complete (63.2% [17.5] v 67.8% [19.3]; not significant) and effective (32.4% [31.95] v 27.25% [22.5]; not significant) waves were definitely low and remained so after treatment. CONCLUSIONS: The esophagus of children with GER has mild disturbances of peristaltic activity with waves often incomplete, weak, and scarcely effective. Dismotility does not improve after successful fundoplication suggesting that it could be a primary phenomenon.

Ambulatory Care↗
PubMed2001

Internal carotid artery thrombus: an underdiagnosed source of brain emboli in neonates?

We report a full-term neonate with a left middle cerebral artery infarct, narrowing of the internal carotid artery detected by magnetic resonance angiography and B-mode ultrasonography, and a large thrombus at the origin of the internal carotid artery detected by B-mode ultrasonography. Internal carotid arterial thrombus is seldom considered the source of middle cerebral arterial embolus in neonates. We suggest that B-mode ultrasonography of the carotid artery be included in the diagnostic evaluation of middle cerebral artery infarcts in neonates.

Carotid Artery Thrombosis↗
PubMed2001

[Intestinal transplantation. First experience in Spain].

UNLABELLED: We present the first case of intestinal transplant (IT) performed in Spacin. CASE REPORT: 28 months old boy with secretory diarrhea since the first month of life, diagnosed of microvillous inclusion disease (MID). He is on total parenteral nutrition (TPN) and had suffered of multiple episodes of catheter related sepsis with lost of standard venous access. An isolated small bowel transplant from a cadaveric donor was performed at the age of 3 years. The native ileocaecal valve and colon were not removed. RESULTS: Enteral feeding was started in the 2nd. week after the IT. On the 25th day he was off TPN. Since the 77th day, he eats regular foods by mouth. At the 6th month post IT the ileostomy was closed. Among the complications, he suffered a rotavirus infection on the 38th post IT day and an episode of mild rejection responsive to methil-prednisolone bolus. CONCLUSIONS: The IT is a therapeutic option that can be already offered with possibilities of success in our country. Although the colonic enterocytes express MVD, the recipient ileocaecal valve and colon can be preserved.

Child, Preschool↗