Biomedical subjects

Luis Jiménez

Publications and source records attributed to Luis Jiménez.

8 recordsLinked to original sources

PubMed2007

Characterization of vine shoots, cotton stalks, Leucaena leucocephala and Chamaecytisus proliferus, and of their ethyleneglycol pulps.

We characterized vine shoots, cotton stalks, Leucaena leucocephala and Chamaecytisus proliferus as pulping raw materials and found C. proliferus and cotton stalks to be the best for the intended purpose on the grounds of their increased contents in holocellulose (79.73% and 72.86%) and alpha-cellulose (45.37% and 58.48%), and their decreased contents in ethanol-benzene extractables (2.64% and 1.42%), hot water solubles (2.79% and 3.33%) and 1% soda solubles (16.67% and 20.34%). These properties resulted in increased pulp yields and hence in efficient use of these two types of raw material. The previous raw materials were pulped by using an ethyleneglycol concentration of 65% at 180 degrees C for 75min, followed by beating at 1500 revolutions in a PFI refiner. The paper sheets obtained were characterized and those from C. proliferus found to be the best overall as they exhibited an increased breaking length (4644m), stretch (2.87%), burst index (2.46kN/g) tear index (0.33mNm(2)/g) and brightness (49.92% ISO); in addition C. proliferus pulp was obtained with a high-yield (62.88%). On the other hand, vine shoots provided the poorest results among the studied raw materials.

Ethylene Glycol↗

PubMed2006

The problem of reversals in assessing implicit sequence learning with serial reaction time tasks.

We report two experiments in which implicit learning is demonstrated within a short session of practice, in the absence of explicit knowledge of what is learned. In Experiment 1, we replicate the experiments by Curran (Psychol Res 60:24-41, 1997a; J Cogn Neurosci 9(4):522-533, 1997b) and highlight the importance of avoiding a random sequence as comparison to the training sequence, due to the higher proportion of reversal trials included in the random one, which leads to an artifactual measure of learning. In Experiment 2 we present a procedure in which two structurally analogous sequences are used both as training and control sequences, thus controlling for any factor different from learning. The results show that implicit learning is obtained within a short session of practice, and in the absence of any explicit knowledge as assessed through a subsequent generation task. We surmise that this procedure might be especially useful in areas in which short procedures are needed, such as when special populations are tested (e.g., patients, children or elderly people) or when the neural bases of implicit learning are being investigated through neurophysiological measures.

Analysis of Variance↗

PubMed2006

Qualitative differences between implicit and explicit sequence learning.

Four experiments investigate the differences between implicit and explicit sequence learning concerning their resilience to structural and superficial task changes. A superficial change that embedded the SRT task in the context of a selection task, while maintaining the sequence, did selectively hinder the expression of implicit learning. In contrast, a manipulation that maintained the task surface, but decreased the sequence validity, affected the expression of learning specifically when it was explicit. These results are discussed in the context of a dynamic framework (Cleeremans & Jiménez, 2002), which assumes that implicit knowledge is specially affected by contextual factors and that, as knowledge becomes explicit, it allows for the development of relevant metaknowledge that modulates the expression of explicit knowledge.

Adult↗

PubMed2005

Effects of short-term supplementation with folic acid on different oxidative stress parameters in patients with hypertension.

Oxidative stress seems to play an important role in the pathophysiology of essential hypertension. Due to its antioxidant features, we studied the protective action of folic acid in hypertensive patients, their food supplemented for 2 weeks with this vitamin. Several oxidative stress parameters were measured in the serum of these patients. The results show that folic acid supplementation improves levels of oxidative stress markers in individuals with hypertension, overall in those patients whose initial parameter values were highest.

Adult↗

PubMed2005

[Abnormal glycemic metabolism in essential hypertension. Role of the an oral glucose tolerance test].

BACKGROUND AND OBJECTIVE: There is a high prevalence of diabetes in essential hypertensive patients, hence increasing the cardiovascular risk of these subjects. Our aim was to test the importance of a routine assessment of an oral glucose tolerance test (OGTT) in a sample of recently diagnosed essential hypertensives. PATIENTS AND METHOD: We studied 270 recently diagnosed untreated hypertensives (56% males). We measured fasting lipids and plasma glucose and insulin at baseline and after OGTT. RESULTS: 38.5% of the studied subjects had any abnormality of glucose metabolism, glucose intolerance (22.2%) and type 2 diabetes (12.2%) being the most common. An impaired fasting glucose was present in 4.1% of subjects. Patients with intolerance or type 2 diabetes had a worse plasma lipid profile, and those with impaired fasting glucose, a higher HOMA index. CONCLUSIONS: The high incidence of glucidic abnormalities found in hypertensive patients signals a need to perform an OGTT test in them. This can lead to the implementation of strategies aimed at halting vascular impairment in hypertensives with type 2 diabetes and delay the development of type 2 diabetes in patients with glucose intolerance.

Adult↗

PubMed2005

Sequence learning under dual-task conditions: alternatives to a resource-based account.

In two experiments with the serial reaction-time task, participants were presented with deterministic or probabilistic sequences under single- or dual-task conditions. Experiment 1 showed that learning of a probabilistic structure was not impaired over a first session by performing a counting task, but that such an interference arose over a second session, when the knowledge was tested under single-task conditions. In contrast, the effects of the secondary task arose earlier for participants exposed to deterministic sequences. This difference between deterministic and probabilistic sequences disappeared in Experiment 2, where the counting task was performed on tones associated to the locations. Comparisons between sessions indicated that the secondary task affected not only the expression but also the acquisition of sequence learning, and that greater interference was observed in those conditions that yielded more explicit knowledge. These results suggest that the effects of a dual task on the measures of implicit sequence learning may be partly due to the intrusion of explicit knowledge and partly due to the disruption of the sequence produced by the inclusion of random events.

Cues↗

PubMed2005

Exercise training in mitochondrial myopathy: a randomized controlled trial.

Patients with mitochondrial myopathies (MM) usually suffer from exercise intolerance due to their impaired oxidative capacity and physical deconditioning. We evaluated the effects of a 12-week supervised randomized rehabilitation program involving endurance training in patients with MM. Twenty MM patients were assigned to a training or control group. For three nonconsecutive days each week, patients combined cycle exercise at 70% of their peak work rate with three upper-body weight-lifting exercises performed at 50% of maximum capacity. Training increased maximal oxygen uptake (28.5%), work output (15.5%), and minute ventilation (40%), endurance performance (62%), walking distance in shuttle walking test (+95 m), and peripheral muscle strength (32%-62%), and improved Nottingham Health Profile scores (21.47%) and clinical symptoms. Control MM patients did not change from baseline. Results show that our exercise program is an adequate training strategy for patients with mitochondrial myopathy.

Adolescent↗

PubMed2003

Reductive genome evolution in Buchnera aphidicola.

We have sequenced the genome of the intracellular symbiont Buchnera aphidicola from the aphid Baizongia pistacea. This strain diverged 80-150 million years ago from the common ancestor of two previously sequenced Buchnera strains. Here, a field-collected, nonclonal sample of insects was used as source material for laboratory procedures. As a consequence, the genome assembly unveiled intrapopulational variation, consisting of approximately 1,200 polymorphic sites. Comparison of the 618-kb (kbp) genome with the two other Buchnera genomes revealed a nearly perfect gene-order conservation, indicating that the onset of genomic stasis coincided closely with establishment of the symbiosis with aphids, approximately 200 million years ago. Extensive genome reduction also predates the synchronous diversification of Buchnera and its host; but, at a slower rate, gene loss continues among the extant lineages. A computational study of protein folding predicts that proteins in Buchnera, as well as proteins of other intracellular bacteria, are generally characterized by smaller folding efficiency compared with proteins of free living bacteria. These and other degenerative genomic features are discussed in light of compensatory processes and theoretical predictions on the long-term evolutionary fate of symbionts like Buchnera.

Base Sequence↗