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Biomedical subjects

J Tovar

Publications and source records attributed to J Tovar.

At least 55 records · Page 3Linked to original sources
PubMed1996

Innovative techniques in pediatric liver transplantation: reduced-, split- and living-donor related liver transplantation.

In spite of the increased number of organ donations, the amount of livers available for pediatric patients does not meet requirements. In an attempt to expand the pool of grafts, several techniques of size reduction (RST) have been developed: reduced-liver transplantation (RLT), liver segment transplantation (LST), "split" liver transplantation (SLT) and living-donor liver transplantation (LDLT). The aim of this work is to study the contribution of these techniques to reduction of mortality in the waiting list and the increased risks that we inflict to our patients by using these procedures. We report our experience on RST in the last nine years (23 RLT, 5 LST, 2 SLT and 3 LDLT). More than a half of them were performed in an emergency. Overall survival in children with RST (67%) is similar to that of patients receiving a "whole graft" (74%). We did not find significant differences in the incidence of graft-related complications, only reintervention for abdominal bleeding was needed more often in the RST group (30%) than in whole graft group (24%). Our data confirm the safety of the RST procedures in the pediatric liver transplantation programs and they decrease the waiting-list mortality (2.5%) among the pediatric patients.

Adolescent↗
PubMed1996

[An experimental model of hepatointestinal transplant in the pig with clinical applications].

A model of experimental hepatointestinal transplant in pigs, with clinical applications is presented. Ten animals received a graft composed by the liver and the full length of the small bowel. Two pigs died during the transplant and in eight the surgical procedure was well tolerated with a good revascularization of the grafts. The coagulation parameters were normal after the transplant and only minor biochemical disturbances were found. The main difficulties of the surgical technique are related with the poor tolerance of the pig to the portal and caval clamping, and the close relationships of the duodenum, pancreas and distal colon, produced by the 360 degrees anti-clockwise bowel rotation around the mesenteric vessels. Clamping the supraceliac aorta during the implant of the graft keeps the animal hemodynamically stable and makes unnecessary the use of the more complicated veno venous shunt.

Animals↗
PubMed1996

Bioavailability of carbohydrates in legumes: digestible and indigestible fractions.

Despite their important contribution to seed weight, carbohydrates in pulses have received limited attention. However, experimental evidence accumulated during the last two decades indicate that legumes are rich sources of slowly digestible starch promoting moderate postprandial glycernic and insulinemic responses. Although the reasons for this phenomenon are not completely understood, some intrinsic properties of the starch itself and the microstructure of cotyledon cells appear to determine much of the slow release character. This beneficial feature is rather sensitive to thermal and mechanical processing. A minimum of 10% of the starch occurring in common beans and lentils escapes digestion and absorption in the normal small intestine, and is therefore referred to as "resistant starch". This material consists mainly of retrograded amylose fractions generated upon cooling of wet-heated pulses. Physically inaccessible starch fractions resulting from cotyledon microstructural properties may also contribute to incomplete digestibility, accounting for up to 40% of the indigestible starch. These indigestible starch fractions are fermented in the large intestine generating gases and volatile fatty acids, compounds that have important influence on the physiology of the colonic mucosa and peripheral metabolism.

Biological Availability↗
PubMed1995

Site-directed mutagenesis of the redox-active cysteines of Trypanosoma cruzi trypanothione reductase.

The gene for trypanothione reductase from the Silvio strain of Trypanosoma cruzi has been cloned, sequenced and overexpressed in Escherichia coli using the constitutive lpp promoter on the expression plasmid pBSTNAV. Up to 13% of the total soluble protein is enzymically active trypanothione reductase with kinetic properties similar to the enzyme purified from T. cruzi. In order to assess the catalytic role of the putative active-site cysteine residues (C53 and C58), three mutant proteins have been constructed by site-directed mutagenesis substituting alanine or serine residues for cysteine; [C53A]trypanothione reductase, [C53S]trypanothione reductase and [C58S]trypanothione reductase. Although the purified, recombinant mutant proteins were catalytically inactive with NADPH and trypanothione disulphide as substrates, all showed comparable levels of transhydrogenase activity between NADPH and thio-NADP+, suggesting that the mutant proteins had correctly folded in vivo. All three mutants showed substantially different catalytic parameters for thio-NADP+ than the wild-type enzyme, presumably as a consequence of modifying the environment of the enzyme-bound flavin, thereby altering its chemical reactivity. The purified [C58S]trypanothione reductase showed spectral properties similar to the oxidised wild-type enzyme but, unlike the wild-type enzyme, did not acquire the characteristic charge-transfer complex of the EH2 form on addition of NADPH. In contrast, in the absence of NADPH both [C53A]trypanothione reductase and [C53S]trypanothione reductase showed spectral properties similar to the EH2 form of the wild-type enzyme. These data indicate that both C53 and C58 are essential for overall catalysis, with the thiolate anion of C58 interacting with the enzyme-bound FAD and C53 interacting with the disulphide substrate. These mutants should be useful in crystallographic studies of reaction intermediates which cannot be obtained with the catalytically active native enzyme.

Animals↗
PubMed1995

Cultured epidermal autograft in the management of critical pediatric burn patients.

We treated 4 patients with CEA at "La Paz" Children's Hospital between July 1992 and September 1993. All of them had acute flame burns. The total body surface area (TBSA) of burn injury ranged from 75% to 85% with an age range of two to five years. Before placement of CEA homografts and biosynthetic materials were used to prepare the wound bed. CEA take ranged from 40% to 90%. One of the children died after polyethylene glycol intoxication when the exposed areas were nearly totally covered. Two more have started rehabilitation therapy and the last patient was grafted just two months ago.

Burns↗
PubMed1994

[Diagnostic consistency between primary care physicians and rheumatologists].

OBJECTIVE: To assess the concordance between the diagnoses on referral from Primary Care to the Rheumatology Clinic and the final diagnoses made by the Rheumatologist. DESIGN: Crossover study. SETTING: Rheumatology clinic in a specialist centre. PATIENTS: The study covered the first 308 patients referred consecutively from Primary Care by Family or General practitioners after the opening of the clinic in 1989. INTERVENTION: A form for referring the patient to the Rheumatologist and filling in the basic data was composed. The referring doctor was also asked to classify the patient in one of five possible diagnostic categories. These diagnoses were compared with the opinion of the Rheumatologist. MEASUREMENTS AND RESULTS: The Family Doctor referred 105 patients and the General Practitioner, 203. The concordance between diagnoses as measured by the Kappa index was 0.61 (C.I. 0.81-0.41) for Family Doctors and 0.38 (C.I. 0.23-0.53) for General Practitioners. CONCLUSIONS: The concordance of diagnoses between Family Doctors and Rheumatologists is good, whereas it was only regular/moderate for General Practitioners, which seems to indicate a superior objective training of Family Doctors in the diagnosis of these patients.

Adult↗
PubMed1994

Food properties affecting the digestion and absorption of carbohydrates.

Carbohydrate foods differ considerably in their effects on postprandial glucose and insulin responses. Qualitative differences among starchy foods are particularly intriguing because of the dominance of starch in human diets. This paper focuses on food properties in cereal (eg, pasta, bread, Arepas, and porridge) and legume products (eg, red kidney beans and lentils) that affect metabolic responses to starch. Studies in healthy subjects have found that postprandial blood glucose and insulin responses are greatly affected by food structure. Any process that disrupts the physical or botanical structure of food ingredients will increase the plasma glucose and insulin responses. The glycemic responses to bread products were reduced by the use of ingredients with an intact botanical or physical structure or a high amylose content or by enrichment with viscous dietary fiber. However, the important of a moderate increase in the amylose-amylopectin ratio and the naturally occurring levels of viscous cereal fiber is less clear. The rate of starch digestion in vitro was shown to be a key determinant of metabolic responses to most products. Assuming the sample preparation mimics chewing, in vitro enzymic procedures can be used to facilitate ranking. One such procedure, based on chewed rather than artificially disintegrated products, was recently developed and correlates well with glycemic and insulinemic indices for several starchy foods.

Animals↗
PubMed1994

[Acute renal failure after major surgery: effectiveness of continuous arterio-venous hemofiltration (CAVH)].

Thirteen patients with acute renal failure after mayor surgery were treated with CAVH, 6 children after liver transplantation (OLT) and 7 after extracorporeal cardiac surgery (ECS). The ages ranged from 4 months to 19 years, with filters from 0.16 m2 to 0.5 m2, according to the weights. CAVH was initiated 19 hours (mean) after OLT and 10.5 hours (mean) after ECS. Mean creatinine clearance was 6.3 ml/min/1.73 m2 (ECS) and 10.1 ml/min/1.73 m2 (OLT). Serum creatinine remained under acceptable values (mean 2.1 mg.%) in both groups. Mean fluid removal was 5.7 L/day (242 ml/kg/day), which allowed plasma administration despite oligoanuria in the OLT group. Fluid removal decreased central venous pressure (p < 0.001) and increased mean arterial pressure (p < 0.01) in the ECS group, and inotropic support could be diminished. CAVH was well tolerated and it was maintained for 79 hours (ECS) and 105 hours (OLT).

Acute Kidney Injury↗
PubMed1992

Incomplete digestion of legume starches in rats: a study of precooked flours containing retrograded and physically inaccessible starch fractions.

The digestibility of starch in precooked flours from green coat lentils (Lens culinaris Medik) and red kidney beans (Phaseolus vulgaris L.) was investigated by balance experiments using rats treated with antibiotics to suppress hind-gut fermentation. The legume preparations were rich in intact cells filled with denaturated starch and contained retrograded amylose. Between 8% (beans) and 11% (lentils) of the total starch ingested appeared in the feces, indicating a relatively low starch digestibility. Red bean flours of two different particle sizes were similarly digested. Sixty percent of the fecal starch in the bean-fed animals and 70% in the lentil-fed group was retrograded amylose. The in vitro indigestible starch content of the flours was evaluated with three different methods that gave rather different values. The retrograded amylose fraction, measured after alkaline treatment of a dietary fiber residue obtained by enzymic digestion, was quantitatively recovered in the feces. None of the procedures gave accurate estimates of the total in vivo indigestible starch. Fecal excretion of starch in rats not treated with antibiotics indicated that the indigestible starch in lentils was less susceptible to fermentation than that in the red bean preparations.

Animals↗
PubMed1992

An in vitro procedure based on chewing to predict metabolic response to starch in cereal and legume products.

A new method for measuring the rate of in-vitro starch digestion in products with a structure 'as eaten' is introduced. An equivalent amount of potentially available starch from each product was chewed by subjects, expectorated into a beaker and incubated with pepsin. The incubate was thereafter transferred to a dialysis tubing and incubated with pancreatic alpha-amylase for 3 h. Samples were removed from the dialysate at time intervals and the degree of hydrolysis was calculated as the proportion of the potentially available starch degraded to maltose. A hydrolysis index (HI) was calculated as the area under the hydrolysis curve with the product as a percentage of the corresponding area with white wheat bread. The method was applied to 21 cereal and legume products, chosen to cover as wide a range as possible with respect to metabolic response, and to include several of the proposed mechanisms to differences in metabolic behaviour of starch. The accuracy of the in-vitro method was evaluated versus the metabolic responses obtained with the same products in healthy subjects. A significant correlation between HI and glycaemic index (GI) was obtained in cereal as well as in legume products. A significant correlation was also obtained between HI and insulin index (II) with pooled data from all products. However, in the case of II no correlation was obtained with the legume products only. It is concluded that the presently described in-vitro procedure offers a good potential to predict the metabolic behaviour of starchy foods.

Digestion↗
PubMed1990

Disturbed hypothalamic-pituitary axis in idiopathic recurring hypersomnia syndrome.

Disturbed function of the hypothalamic-pituitary axis at adrenal and thyroid levels was found during an episode of hypersomnia in the idiopathic recurring hypersomnia syndrome. These endocrinological abnormalities, abolished ACTH and cortisol responses to insulin-induced hypoglycemia and absent TSH response to TRH, normalised thereafter in the symptom-free interval. These data support the hypothesis that Kleine-Levin syndrome is related to an intermittent hypothalamic dysfunction.

Adolescent↗