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C Corredor

Publications and source records attributed to C Corredor.

10 recordsLinked to original sources
PubMed2006

Diffusion of (226)Ra and (40)K radionuclides reproduced in underwater sedimentary columns in laboratory.

The potential radiological impact of the increase of radioactive substances in the environment makes interesting the study of the migration of the contaminant radionuclides in soils and sediments, which are the last receiver system of these substances. By using a battery of sedimentary columns controlled in the laboratory, the diffusion of the (226)Ra and (40)K radionuclides has been studied, assessing their respective effective diffusion coefficients in a similar sedimentary medium. A decreasing temporal evolution is obtained, associated to the progressive 'fixation' of the radionuclides by the clay minerals of the sediment, followed by a constant tendency. A timescale of the 'fixation' by the sediment is determined, being of the order of days for (226)Ra and of the order of months for (40)K, so the progressive 'fixation' of (40)K by the clay minerals of the sediments is slower than in the case of (226)Ra.

Aluminum Silicates↗
PubMed2005

Comparison of treatment planning dose calculations with measurements and Monte Carlo calculations in a RANDO phantom.

Solid tumours are often treated with external beams of photons generated by Bremsstrahlung radiation. These beams are shaped and filtered to optimise the dose to specific regions defined by the treatment plans, which may involve irradiations from multiple angles. It is important that doses to healthy tissue do not exceed tolerance doses and that the dose to the tumour is maximised. To accomplish these objectives, commercially available 3-D treatment planning software is used to calculate doses to healthy tissue and to the tumour. It is generally believed that these commercial software packages calculate doses through the patient to within a few per cent. In order to examine this claim, dose calculations obtained from ADAC software for external beam treatment to the pelvic region of a RANDO phantom are compared with 37 thermoluminescence dosemeters placed into several slices of a RANDO phantom. The phantom was irradiated to obtain a prescription dose of 180 cGy at the tumour location. Data from homogeneous regions agree within several per cent with results obtained from ADAC software, whereas this comparison is less favourable in regions of heterogeneity. Results from Monte Carlo calculations in a homogeneous phantom are comparable to results from ADAC treatment planning software.

Computer Simulation↗
PubMed2004

Ionotropic glutamate receptor activated by N-methyl-D-aspartate: a key molecule of conscious life.

We want to propose that basic stereotyped integrative functions are the result of sequentially built neuronal circuits in the primitive regions of the brain in whose build-up a particular subunit composition iGluR-NMDA would play a central role. iGluR-NMDA is a multiregulated heteromeric glutamate receptor-ion channel found in plasma membranes of neurons and other cells. iGluR-NMDA may be composed of up to five subunits, depending on the type of cell involved and its location. There are three major types of subunits and there are variations within each type allowing for up to 13 possible subunits, at least in the rat, which differ from each other in amino acid sequence and thus, in tertiary structure. The actual iGluR-NMDA heteropolymer involved in a given function may thus have a great number of subunit composition possibilities which would be the result of the particular genes expressed in a given type of cell. The iGluR-NMDA is an ion channel that opens in response to glutamate in a highly regulated fashion in which different molecules and ions present in the interstitial fluid determine whether or not the channel opens upon glutamate binding. The original function of iGluR-NMDA may have been that of allowing calcium influx to cells. As the brain receives external stimuli through the senses, new circuits will be formed stepwise in the neocortex in which a particular subunit composition iGluR-NMDA will be involved. Differentiation between external stimuli generated circuits and those governing internal functions will allow distinction between self and non-self, thus generating conscious awareness. The role of the particular subunit composition iGluR-NMDA proposed would be that of providing a means of calcium influx to the synapses to be formed and, if the same stimulus is forthcoming, allowing permanent synapses formation through the membrane incorporation of calcium dependent adhesion molecules such as cadherins and cytoskeleton reorganization promoted by nectins.

Brain↗
PubMed1991

Neurophysiologic assessment of the anal sphincters.

One hundred twenty consecutive patients with either fecal incontinence (60 patients), chronic constipation (41 patients), or idiopathic intractable pelvic pain (19 patients) were prospectively assessed. Patients underwent concentric needle electromyography (EMG), bilateral pudendal nerve terminal motor latency evaluation, anorectal manometry, and cinedefecography. The most common EMG finding in patients with fecal incontinence was decreased recruitment of motor units with squeezing and polyphasic motor unit potentials; these are consistent with an injury pattern. The most common EMG finding in the constipated patients was paradoxical puborectalis contraction. This latter abnormality was also a frequent finding in patients with rectal pain, as was prolongation of pudendal nerve latency. Paradoxical puborectalis contraction was diagnosed more frequently with EMG than with cinedefecography. Inter-examination correlation was best in the incontinent group between EMG and manometry. Cinedefecography had poor correlation with EMG in all patient groups but was valuable in the detection of additional pathology such as rectoanal intussusception and anterior rectocele. Electromyography including pudendal nerve terminal motor latency assessment is a valuable adjunct in the evaluation of disorders of evacuation. The information it yields is complementary to that offered by more routine physiologic examinations.

Anal Canal↗
PubMed1984

Biphasic effect of fructose 2,6-bisphosphate on the liver fructose-1,6-bisphosphatase: mechanistic and physiological implications.

Fructose 2,6-bisphosphate has been claimed to be both a substrate analogue and an allosteric inhibitor of fructose-1,6-bisphosphatase. The results reported here show that fructose 2,6-bisphosphate can be both an inhibitor and an activator of the enzyme, depending on the substrate concentration. This biphasic behaviour at saturating concentrations of substrate can only be due to an allosteric effect. In addition to the mechanistic implication it is possible that this finding may have physiological meaning.

Animals↗
PubMed1980

Significance of focal and lateralized beta activity in the EEG.

In a group of 16,432 EEGs studied in a five year period, a total of 43 with focal, lateralized or paroxysmal beta activity were noted. The focal beta activity was mainly seen in children suffering from intractable seizures secondary to A-V malformation, porencephalic cysts or tumors. This was practically an epileptiform discharge with a high clinical pathologic correlation. The lateralized beta activity was seen mainly in adults suffering from cerebrovascular disease or tumor. In the cerebrovascular group the lateralized activity was seen on the contra-lateral side of the lesion. The paroxysmal beta activity is a rare phenomenon seen purely as an ictal manifestation, and mainly seen in children with Lennox-Gastaut Syndrome or infantile spasms. The importance of proper technique to record such abnormalities is emphasized.

Adolescent↗