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Biomedical subjects

J Tomás

Publications and source records attributed to J Tomás.

At least 19 recordsLinked to original sources
PubMed2004

A cardiological web as an adjunct to medical teaching: prospective analysis.

The aim of the study was to deliver and evaluate an educational web for medical students. A web of the complete cardiovascular course was prepared as an adjunct educational material for the classes. The use and utility of the web was assessed through a questionnaire (frequency of use, impact on in-class attendance and students' satisfaction). The number of visits, the time of the week and the hour when the web was used were registered. A total of 76 students returned the questionnaire. The web was available for 10 weeks and was visited 1062 times, especially at weekends. An increase in visits was noted prior to final examination. The web was accessed preferentially from the faculty or hospital computers. The quality of the web was assessed and rated a mean of 7.7 (score: 1-10); 93.4% students attended the class, but the web freed them from transcribing the contents; 88.2% of students evaluated the web as a useful or very useful adjunct to medical teaching. The Internet can be used to deliver learning in medical students and could be considered as added value to the pedagogic process and did not deter students from attending ordinary classes.

Cardiology↗
PubMed2004

[General anesthesia by infusion of remifentanil for debridement and grafting of large burns in 3 pediatric patients].

Three 13-year-olds with burns on 30%, 70%, and 75% of their body surface areas and with related respiratory tract lesions underwent multiple surgical interventions for debridement, graft placement, and topical treatments. Balanced general anesthesia was provided with sevoflurane and an infusion of remifentanil and cisatracurium. Each patient underwent 41 procedures over a period of 6 months. All interventions were carried out without complications other than the difficulty of establishing an access to veins and monitoring because of the scarcity of intact surfaces. Remifentanil is an effective analgesic for meeting the needs of patients with severe burns. The combination of remifentanil, sevoflurane, and cisatracurium provides good hemodynamic stability and is very appropriate for patients who must undergo a large number of surgical interventions.

Adolescent↗
PubMed2002

Marine debris ingestion in loggerhead sea turtles, Caretta caretta, from the Western Mediterranean.

Marine debris represents an important threat for sea turtles, but information on this topic is scarce in some areas, such as the Mediterranean sea. This paper quantifies marine debris ingestion in 54 juvenile loggerhead sea turtles (Caretta caretta) illegally captured by fishermen in Spanish Mediterranean waters. Curved carapace length was measured, necropsies were performed and debris abundance and type was recorded. Different types of debris appeared in the gastrointestinal tract of 43 turtles (79.6%), being plastics the most frequent (75.9%). Tar, paper, Styrofoam, wood, reed, feathers, hooks, lines, and net fragments were also present. A regression analysis showed that the volume of debris increased proportionally to the size of the turtles. The high variety of debris found and the large differences in ingestion among turtles indicated low feeding discrimination of this species that makes it specially prone to debris ingestion. Our data suggest that more severe control of litter spills and greater promotion of environmental educational programmes are needed in the Western Mediterranean.

Age Factors↗
PubMed2001

Calcium channels coupled to neurotransmitter release at dually innervated neuromuscular junctions in the newborn rat.

We studied the effect of several calcium channel blockers (omega-Conotoxin-GVIA, 1 and 3microM; omega-Agatoxin-IVA, 100nM; Nitrendipine, 1 and 10microM) on evoked transmitter release at singly and dually innervated endplates of the levator auris longus muscle from three- to six-day-old rats. In dually innervated fibers, a second endplate potential may appear after the first one when we increase the stimulation intensity. The lowest and highest endplate potential amplitudes are designated "small endplate potential" and "large endplate potential", respectively. The percentage of doubly innervated junctions remains almost constant throughout the age range examined. Nevertheless, the percentage of junctions innervated by three or more terminal axons drops, whereas the singly innervated junctions increase. Therefore, between postnatal days 3 and 6, roughly half the neuromuscular junctions may experience the final process of axonal elimination. The synaptic efficacy of the large endplate potential in dual junctions, measured as the mean amplitude of the synaptic potential and mean quantal content, was the same as in the junctions that had become recently mono-innervated in the same postnatal period. In singly innervated fibers, the endplate potential size was strongly reduced by both the P/Q-type voltage-dependent calcium channel blocker omega-Agatoxin-IVA (79.17+/-4.02%; P < 0.05) and the N-type voltage-dependent calcium channel blocker omega-Conotoxin-GVIA (56.31+/-7.80%; P < 0.05), whereas endplate potential amplitude was not significantly changed by the L-type voltage-dependent calcium channel blocker Nitrendipine. In dually innervated fibers, the P/Q-type voltage-dependent calcium channel blocker omega-Agatoxin-IVA and L-type voltage-dependent calcium channel blocker Nitrendipine increased the size of the small endplate potential (161.29+/-47.87% and 109.32+/-11.03%, respectively; P < 0.05 in both cases) and reduced the large endplate potential (74.42+/-15.32% and 70.91+/-10.04%, respectively; P < 0.05 in both cases). The N-type voltage-dependent calcium channel blocker omega-Conotoxin-GVIA significantly increased the small endplate potential in the first few minutes after toxin application (at 10min: 90.23+/-17.38%; P < 0.05). This increase was not maintained, while the large endplate potential was strongly inhibited (69.25+/-7.5%; P < 0.05). In conclusion, in the dually innervated endplates of the newborn rat, presynaptic calcium channel types can have different roles in transmitter release from each of the two inputs, which suggests that nerve terminal voltage-dependent calcium channels are involved in neonatal synaptic maturation.

Aging↗
PubMed1996

Bacteriocin 28b from Serratia marcescens N28b: identification of Escherichia coli surface components involved in bacteriocin binding and translocation.

Serratia marcescens N28b produces bacteriocin 28b, active against Escherichia coli. Bacteriocin sensitivity tests performed on a collection of E. coli envelope mutants, and isolation and characterization of E. coli bacteriocin-28b-insensitive mutants, showed that the core lipopolysaccharide, outer membrane proteins OmpA and OmpF, and TolQ, TolA, and TolB proteins are involved in bacteriocin 28b lethal activity. These mutants are assayed for bacteriocin 28b sensitivity under normal and bypass conditions, and their bacteriocin-binding ability was determined. The results obtained suggest that the core lipopolysaccaride and outer membrane proteins OmpA and OmpF are involved in bacteriocin 28b binding. Furthermore, bacteriocin 28b translocation requires proteins TolA, TolB, and TolQ.

Bacterial Outer Membrane Proteins↗
PubMed1994

Oral chloral hydrate provides effective and safe sedation in paediatric magnetic resonance imaging.

Sedation is routinely required for successful Magnetic Resonance imaging in infants and children. Five hundred and ninety-six paediatric patients (270 female and 326 male, age (mean +/- SD) 41 +/- 30 months and weight 14.8 +/- 6.5 kg) entered an open, non-comparative, prospective study to assess oral chloral hydrate sedation in a large and homogeneous paediatric population undergoing Magnetic Resonance imaging. Chloral hydrate syrup 70 mg/ml was administered 20-40 min prior to the procedure. Effective sedation was reached in 94.1% with a total dose (mean +/- SEM) of 68 +/- 1 mg/kg (range 20-170 mg/kg). Statistical analysis of sedation failures vs. successful examinations after the total dose showed significant differences for dose (62 +/- 4 vs. 69 +/- 1 mg/kg; P < 0.05), age (64 +/- 7 vs. 40 +/- 1 months; P < 0.001) and weight (19.8 +/- 1.5 vs. 14.5 +/- 0.0 kg; P < 0.001). Effectiveness fell to around 80% in children with encephalic white matter alterations, medullary tumours or syringohydromyela (P = 0.07). The mean time of onset of sedation was 26 +/- 1 min, and the mean time to spontaneous awakening after the completion of the Magnetic Resonance examination was 38 +/- 2 min. Fifty-nine children (9.9%) experienced adverse reactions, with nausea and vomiting being the most common (n = 41), followed by nervousness and unusual excitement (n = 6). Discriminant function analysis identified age and total dose as the quantitative variables helping to differentiate between sedation failures and satisfactory examinations (sensitivity = 0.73, and specificity = 0.61; r = 0.20, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1992

[The effect of Bentazone, a Czechoslovak developmental herbicide, on health status indicators in sheep during subchronic poisoning].

A three-month feeding trial was conducted with sheep of the Slovak Merino breed (13-14 months of age, males and females) as a part of the obligatory toxicological tests of the Czechoslovak developmental herbicide bentazone (Research Institute for Chemical Technology, Bratislava). Partial results are shown describing the action of this herbicide on the overall health of sheep with respect to weight gains, trias values and intrauterine foetus development. The sheep of the first experimental group were fed bentazone as an additive to molasses feed M at a daily rate of 195 mg/kg lwt. (1/10 from LD50), and the sheep of the second group were fed a rate of 97.5 mg/kg lwt. (1/20 from LD50). No symptoms of the toxic effects of bentazone were observed in the course of the experiment. There were no differences between the experimental and test animals in the dynamics of pulse value changes (Fig. 1), breathing value changes (Fig. 2) and body temperature value changes (Fig. 3) from the beginning till the end of the trial. A slight increase in the pulse and breathing values above the upper reference value observed in the experimental groups in the last two to three weeks of the trial cannot be associated with the bentazone action. This increase reflects the physiological condition of the animals in the given conditions because the identical changes were also found in the control group. We assume that the changes were evoked by the elevated temperature of the external environment due to the fact that the sheep were not sheared.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Evaluation of the pre-S (pre-S(1)Ag/pre-S(2)Ab) system in hepatitis B virus infection.

The diagnostic and prognostic value of pre-S(1)Ag and pre-S(2)Ab was investigated in 69 HBsAg surface antigen positive patients--14 with acute hepatitis B, 30 with chronic liver disease (six chronic persistent hepatitis, 14 chronic active hepatitis, 10 with cirrhosis) and in 25 asymptomatic carriers. Pre-S(1)Ag was found in all patients with chronic hepatitis B virus (HBV) infection regardless of viral replication. In contrast, pre-S(2)Ab was not detected in any patients. Acute hepatitis was studied sequentially with periodic controls at 20 day intervals. Pre-S(1)Ag cleared before HBsAg in six of 14 (43%) patients who progressed favourably, and the two antigens cleared simultaneously in eight of 14 (57%) cases. Patients with early clearance of pre-S(1)Ag progressed favourably, thus indicating the prognostic value of this test, which, however, is still of limited practical application given the small temporal difference between the moment of clearance of the two antigens. The first markers to clear, however, were HBeAg and DNA-HBV, which showed significant differences with respect to the clearance of HBsAg. Moreover, pre-S(2)Ab appeared before HBsAb in 57.1% of our patients and was found in some patients before pre-S(1)Ag and HBsAg had cleared (42.8%), thus allowing complete viral clearance and acute HBV infection to be predicted earlier.

Biomarkers↗
PubMed1990

[Elution of bacteria adhering to the epithelium in the rumen in sheep and their detection using electron microscopy].

A method of preparing the pure concentrate of epithelium-adherent bacteria in sheep rumen was worked out and it was tested in 24 samples of the rumen wall, obtained from 12 slaughtered sheep. The purity of the bacterial eluate was checked by transmission electron microscopy and negative staining, followed by electron-microscopic evaluation. Besides bacterial cells no residues of feed, epithelium and other undesirable impurities were found out in the eluate. The percent yield of this method was determined by scanning electron microscopy and it made 93.3%. An isolated pure concentrate of the mixture of bacterial cultures, previously adhered to the rumen epithelium, was prepared which can be used for morphological and biochemical studies of this interesting group of rumen bacteria.

Animals↗
PubMed1990

[Changes in amino acid levels in bacteria adhering to rumen epithelium in sheep after oral administration of very low doses of mercury].

The effect of low concentrations of mercury taken in the diet (4 mg per a head and day) on the amino acid composition in the proteins of rumen bacteria adhering to the dorsal and ventral parts of the rumen was studied in six sheep. Though the mercury did not influence the amino acid concentration in hydrolyzates of epimural bacteria, low-mercury doses caused significant changes of some amino acids, as compared with the control group of animals. The levels of alanine, histidine, threonine, serine and glycine were significantly decreased and at the same time the levels of proline, valine, isoleucine, tyrosine, lysine and phenylalanine were significantly increased. It was stated in our experiment that the levels of histidine, alanine and threonine in hydrolyzates of epimural bacteria of the rumen were significantly decreased both in the sheep given the balanced feed ration with additions of mercury and nitrogen (according to the standard) and in the sheep given a low-nitrogen diet. Similarly, the levels of proline, tyrosine and phenylalanine in the hydrolizates of epimural bacteria in rumen were significantly increased both with the low-nitrogen diet and in the normal -nitrogen diet with mercury supplement. The results suggest that unexplained disorders frequently occurring in the microbial synthesis in the rumen might be caused by long-continued administration of feed contaminated with extremely low concentrations of heavy metals. The problem deserves detailed investigation in future studies, oriented to explaining the biosynthesis disorders in rumen, reducing the production ability of ruminants.

Administration, Oral↗
PubMed1989

[Our 2-year experience with diagnostic arthroscopy of the knee joint].

The authors performed 200 arthroscopic examinations of the knee joint from April 1986 through March 1988. A suspected lesion of medial meniscus (in 52.5%) was the most frequent indication for the examination. Chondromalatia of patella was the most frequent arthroscopic finding (in 50.5% of examinations), two thirds of these findings were clinically inapparent. The ratio of arthroscopic findings of damage on the medial and lateral meniscus was 1.5:1. The lesions of medial meniscus were more frequently erroneously diagnosed clinically (32.4%), than the lateral meniscus lesions (25%), whereas the rupture of lateral meniscus was a more frequent accidental finding (19%) as compared with medial meniscus (11%). In 35% of cases the diagnostic arthroscopy saved the patient a useless revision of the joint. Reliability of the arthroscopic findings evaluated according to subsequent revisions proved to be 90.7%.

Adolescent↗
PubMed1986

[Training in digestive endoscopy. Considerations, experiences and methodological contributions].

The bibliographical contributions on education in digestive endoscopy and the need of establishing in Argentina a curricular programming for its teaching-learning are considered. The experience of the authors acquired during the giving of eight Basic or initiation Courses and eight Advanced or Improvement Courses is presented. They used in them six didactic simulators and endoscopic cinematography that completed the written simulations. Conceptual and methodological aspects are exposed to perform the curricular programming of training comprising the student from the student of Medicine to the gastroenterologist or surgeon more devoted or specialist in digestive endoscopy.

Argentina↗
PubMed1984

P1 bacteriophage and tellurite sensitivity in Klebsiella pneumoniae and Escherichia coli.

Klebsiella pneumoniae and Escherichia coli respond inversely toward P1 bacteriophage or TeO3(-2). Klebsiella pneumoniae is resistant to both antagonists and E. coli is sensitive. However, P1 cmts lysogens (P1 cmts resistant) of K. pneumoniae became sensitive to tellurite and when cured from P1 cmts regained resistance. Escherichia coli spontaneous mutants selected for resistance to either P1 or TeO3(-2) were collaterally resistant to the other. As well, TeO3(-3) enhanced the adsorption of P1 vir to both E. coli and K. pneumoniae. Several outer membrane proteins were enhanced in the K. pneumoniae lysogens and were reduced in E. coli lysogens; one of which was the same molecular weight (77 000) in both bacteria. When partially purified it enhanced the plaque efficiency of P1 vir. Lipopolysaccharide (LPS) from E. coli C600 inactivated P1 vir, but neither the P1 lysogens nor LPS derived from the lysogens inactivated P1 vir. Escherichia coli P1 lysogens produced only heptose-deficient LPS. It is suggested that both LPS and outer membrane protein(s) comprise the P1 receptor. TeO3(-2) may interact with one or both components.

Adsorption↗