Biomedical subjects

J Rodríguez-Hernández

Publications and source records attributed to J Rodríguez-Hernández.

4 recordsLinked to original sources

PubMed2006

pH-responsive micelles and vesicles nanocapsules based on polypeptide diblock copolymers.

The self-assembly of well-defined polypeptide-based diblock copolymers into micelles and vesicles is presented. The stimuli-responsive behavior of polypeptides to pH and ionic strength is used to produce stimuli-responsive nanoparticles with controlled size and shape. Results focusing on micelles and vesicles obtained from polypeptide-based diblock copolymers that are particularly promising for biomedical applications are detailed by means of static and dynamic light scattering analysis, UV circular dichroism, NMR and small angle neutron scattering experiments. Also systems able to form vesicles with a narrow size distribution at basic and acid pH going through a single molecule intermediate state are presented. These nanoparticles are particularly interesting for encapsulation and delivery purpose at a controlled pH.

Capsules↗

PubMed1996

Seasonal prevalences of Cryptosporidium and Giardia infections in children attending day care centres in Salamanca (Spain) studied for a period of 15 months.

Five studies were carried out in children younger than 4 years old attending regularly day care centres in order to determine the intestinal parasitization by Cryptosporidium and Giardia. The percent of children parasitized by Cryptosporidium was 10% (17 children out of 170 studied). Cryptosporidiosis was more frequent in winter than in other seasons (difference statistically significant). Giardia intestinalis, which was the most frequent parasite, was identified in 25.3% (43 children out of 170 studied). Giardiasis was more frequent in autumn and in the low SEL (difference statistically significant in both cases). The frequency of giardiasis increased from 8% in children studied during 1-2 seasons, to 34% in children studied for 3-5 seasons (difference statistically significant), whereas the frequency of cryptosporidiosis did not show variation with increased number of specimens studied per child. The 35% of children parasitized by Cryptosporidium sp. showed gastrointestinal symptoms but only 14% of children with Giardia intestinalis.

Animals↗

PubMed1992

Epidemiology and clinical significance of Blastocystis hominis in different population groups in Salamanca (Spain).

A prospective study was carried out to investigate the epidemiology and clinical significance of Blastocystis hominis in the following groups of the population of the city of Salamanca (Spain): in children attending 11 day care centres and 7 primary schools, two fecal samples were obtained from each child, and in 1231 patients attending the Clinical Hospital. A B. hominis incidence of 5.3-10.3% was found in the day care centres and an incidence rate of 13.4-19.4% was found in the primary schools. All the cases were observed in asymptomatic children. The incidence of B. hominis was greater in children older than 3 years in the day care centres and in the 10-14 year-old group in the primary schools. A heavier parasitization was observed in the boys than in the girls and in the students of schools in areas of low socio-economic level. B. hominis was identified in 40 patients attending the Clinical Hospital (3.25% of all those studied). The maximum peak of incidence was found in subjects with ages between 10 and 14 years. A follow up study was performed on 18 patients parasitized exclusively by B. hominis; 7 of these were considered to have acute gastroenteritis and one chronic gastroenteritis associated with the protozoan. No statistically significant association was observed between the number of B. hominis cells and the presence of diarrhoea. Our results show that despite the high number of asymptomatic carriers of B. hominis in the juvenile population, this protozoan may be, on other occasions, responsible for gastrointestinal symptoms.

Adult↗

PubMed1991

Postsynaptic antagonism by 4-aminopyridine of ketamine effect in frog (Hyla crepitans) neuromuscular junctions.

The action of ketamine (50 microM) and 4-aminopyridine (4-AP) (50 microM) on the frog (Hyla crepitans) neuromuscular junction using standard intracellular recording techniques was investigated. In our experiments the amplitude of evoked end plate potential was decreased by ketamine and increased by 4-AP, which is similar to the effects reported by other investigators. However, novel effects of the drugs on postsynaptic acetylcholine receptors were detected when miniature end plate potential (MEPP) amplitude and time-course were analyzed. The experiments were performed and registered in presence of 1% dimethylsulfoxide to augment frequency of MEPP's. When ketamine was added to the saline solution, MEPP amplitude control values were reduced from 226 (214, 240) microV (n = 529, median and its 95% confidence interval) to 140 (130, 151) microV (n = 143) by 50 microM ketamine. 4-AP alone also depressed MEPP amplitude to 129 (70, 152) microV (n = 91). The two drugs are partial antagonists, when they were applied together, MEPP amplitude was 180 (172, 188) microV (n = 207). The effect of ketamine on time course of MEPP's, expressed as time to peak, reduced the control values of 4.74 (4.61, 4.88) msec (n = 529) to 3.84 (3.72, 4.01) msec (n = 143) (P less than 0.001); the effect of 4-AP was to reduce the control values to 1.93 (1.79, 2.10) msec (n = 91). The time to peak after adding ketamine and 4-AP was 3.25 (3.12, 3.38) msec (n = 207), expressing an antagonistic effect of the drugs. All values are statistically distinct (P less than 0.001). Thus, our results show that a postsynaptic mechanism is responsible for a significant part of the antagonism of ketamine effects by 4-AP.

4-Aminopyridine↗