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Biomedical subjects

L Quintanar

Publications and source records attributed to L Quintanar.

7 recordsLinked to original sources
PubMed2001

Spectroscopy and reactivity of the type 1 copper site in Fet3p from Saccharomyces cerevisiae: correlation of structure with reactivity in the multicopper oxidases.

Fet3p is a multicopper oxidase recently isolated from the yeast, Saccharomyces cerevisiae. Fet3p is functionally homologous to ceruloplasmin (Cp) in that both are ferroxidases. However, by sequence homology Fet3p is more similar to fungal laccase, and both contain a type 1 Cu site that lacks the axial methionine ligand present in the functional type 1 sites of Cp. To determine the contribution of the electronic structure of the type 1 Cu site of Fet3p to the ferroxidase mechanism, we have examined the absorption, circular dichroism, magnetic circular dichroism, electron paramagnetic resonance, and resonance Raman spectra of wild-type Fet3p and type 1 and type 2 Cu-depleted mutants. The spectroscopic features of the type 1 Cu site of Fet3p are nearly identical to those of fungal laccase, indicating a very similar three-coordinate geometry. We have also examined the reactivity of the type 1 Cu site by means of redox titrations and stopped-flow kinetics. From poised potential redox titrations, the E degrees of the type 1 Cu site is 427 mV, which is low for a three-coordinate type 1 Cu site. The kinetics of reduction of the type 1 Cu sites of four different multicopper oxidases with two different substrates were compared. The type 1 site of a plant laccase (Rhus vernicifera) is reduced moderately slowly by both Fe(II) and a bulky organic substrate, 1,4-hydroquinone (with 6 equiv of substrate, k(obs) = 0.029 and 0.013 s(-)(1), respectively). On the other hand, the type 1 site of a fungal laccase (Coprinus cinereus) is reduced very rapidly by both substrates (k(obs) > 23 s(-)(1)). In contrast, both Fet3p and Cp are rapidly reduced by Fe(II) (k(obs) > 23 s(-)(1)), but only very slowly by 1,4-hydroquinone (10- and 100-fold more slowly than plant laccase, respectively). Semiclassical theory is used to analyze the origin of these differences in reactivity in terms of type 1 Cu site accessibility to specific substrates.

Ceruloplasmin↗
PubMed1989

Detection of brain damage: neuropsychological assessment in a Spanish speaking population.

We developed a neuropsychological battery for assessment of cognitive processes that was standardized in 150 neurologically intact subjects from different socioeducational levels in Mexico City (Ostrosky et al., 1985, 1986). The present study was designed to explore the capacity of this neuropsychological battery to discriminate a brain-injured population from a normal one. Thirty-four patients attending the neurological service of two hospitals institutions in Mexico City were studied. The reasons for going to the hospital included both neurological and neuropsychological symptoms. The group was divided into two subgroups: twenty-four patients who showed brain damage confirmed by brain scans, and ten patients with a normal brain scan. A control group of 19 normal subjects was also studied and paired with the other groups by sex, age and sociocultural level. The results show that the neuropsychological battery was able to recognize 83.3% of the patients with scanographically confirmed brain damage: the total percentage of successful diagnosis was 88.2% and there were no false positives. These results indicate that neuropsychological assessment is a powerful diagnostic procedure that also evaluates the patient's cognitive-behavioral activity and can help to predict the possibilities for rehabilitation and return to work.

Adult↗
PubMed1988

Neuropsychological effects of brain autograft of adrenal medullary tissue for the treatment of Parkinson's disease.

We describe the pre- and postoperative neuropsychological profiles of seven patients who received an autograft of adrenal medullary tissue to the caudate nucleus for the treatment of Parkinson's Disease (PD). The preoperative neuropsychological evaluations revealed specific cognitive deficits of varying degree. The patients showed frontal lobe-type deficits with alterations in behavioral programming leading to difficulties in the organization of motor sequences and alternating programs. They also showed memory disorders and visuospatial and visuoperceptual deficiences such as a loss of figure-ground perspective and fragmentation. Postoperative evaluations, carried out 3 months after neurosurgery, revealed a significant amelioration of the frontal lobe-type symptoms and visuospatial deficits, as well as an improvement in memory tasks that require an active organization of the response. Immediate and delayed memory difficulties remained unchanged. These observations were compared to neuropsychological data obtained from neurologically intact subjects and from unoperated PD patients. The improvements of the operated PD patients resulted in performance levels close to normal values and clearly distinguishable from those of unoperated PD patients, and were unrelated to improved mood, increased alertness, or sustained attention. Autotransplantation of adrenal medullary tissue to the caudate nucleus of PD patients showing a decreased effective response to L-dopa therapy can partially restore motor functions and frontal-type cognitive symptoms.

Adrenal Medulla↗
PubMed1985

Sociocultural effects in neuropsychological assessment.

The group selected for this evaluation consisted of 109 normal people with an average age of 25, coming from two different sociocultural levels (high and low) of Mexico City. All were completely evaluated by Luria's battery for neuropsychological assessment, adapted by Ardila, Ostrosky, and Canseco, 1981. This group of tests measures nine different areas: Motor Functions, Somatosensory Knowledge, Auditory Knowledge, Visuospatial Knowledge, Cognitive Processes, Language, Reading, Writing and Basic Calculations. For all of these, the higher performance standards were achieved by the subjects from the high sociocultural level. A significant interaction between sociocultural level and sex was observed. The differences between sexes appear only in subjects from the low sociocultural level. Factor analysis of the battery revealed that the most sensitive items to sociocultural level were those related on one hand, to the handling of complex structural and conceptual aspects of language and on the other hand, to the organization of motor sequences and in general motor programming. Research related to the differences found is reviewed and implications for clinical assessment are discussed.

Adult↗