Biomedical subjects

C Mucignat

Publications and source records attributed to C Mucignat.

11 recordsLinked to original sources

PubMed2003

High-performance liquid chromatographic assay for the determination of Aloe Emodin in mouse plasma.

An isocratic high-performance liquid chromatography (HPLC) method was developed and validated to determine Aloe Emodin (AE) in mouse plasma. The analysis required 0.3 ml of plasma and involves extraction with dichloromethane. The HPLC separation was carried out on Symmetry Shield RP18, a mobile phase of methanol-water-acetic acid (65:35:0.2) and fluorescence detection at lambda(ex)=410 nm and lambda(em)=510 nm. The retention time of AE was 11.7 min. The assay was linear from 10 to 1,000 ng/ml (r2 > or = 0.999), showed intra- and inter-day precision within 7.8 and 4.7%, and accuracy of 87.3-105.7%. Detection limit (LOD) and quantification limit (LOQ) were 4.5 and 5 ng/ml, respectively. The method was applied to determine for the first time the pharmacokinetic of AE in mice.

Animals↗

PubMed2000

Aloe-emodin is a new type of anticancer agent with selective activity against neuroectodermal tumors.

Here we report that aloe-emodin (AE), a hydroxyanthraquinone present in Aloe vera leaves, has a specific in vitro and in vivo antineuroectodermal tumor activity. The growth of human neuroectodermal tumors is inhibited in mice with severe combined immunodeficiency without any appreciable toxic effects on the animals. The compound does not inhibit the proliferation of normal fibroblasts nor that of hemopoietic progenitor cells. The cytotoxicity mechanism consists of the induction of apoptosis, whereas the selectivity against neuroectodermal tumor cells is founded on a specific energy-dependent pathway of drug incorporation. Taking into account its unique cytotoxicity profile and mode of action, AE might represent a conceptually new lead antitumor drug.

Animals↗

PubMed1999

Pheromone signalling in the mouse: role of urinary proteins and vomeronasal organ.

The lipocalin protein family is characterized in structure by a conserved hydrophobic pocket which can bind small volatile odorants. The Major Urinary Proteins (MUPs) are a class of lipocalins found in the urine of adult male mice which concentrate in the urine odorants which confer a characteristic odor. The behavioural as well as the endocrine effects of mouse urine and MUPs are briefly reviewed, suggesting a complex role is pheromonal communication. Some recent data on the molecular receptors of the vomeronasal organ further suggest a complex interaction with the MUP system.

Alpha-Globulins↗

PubMed1994

Left-right asymmetry of callosal transfer in normal human subjects.

Interhemispheric transfer (IT) of visuomotor information can be assessed by measuring the crossed-uncrossed difference (CUD) in the Poffenberger paradigm [14]. We report a series of experiments aimed at casting light on two aspects of IT: the importance of motor response variables and the nature of the left-right asymmetries found in a recent meta-analysis of studies using the Poffenberger paradigm [10]. In Experiments 1 and 2 we found no effect of varying the finger used for response while there was a larger CUD when using the left hand in comparison to the right hand. In Experiment 3, which employed visual stimuli different from the two preceding experiments, CUD asymmetries were related to hemifields rather than to hands with a CUD larger for the right than for the left visual hemifield. These findings suggests that both motor and visual variables are important for CUD asymmetries to occur and are in keeping with a horse race model according to which overall speed of IT is determined by whichever signal (visual or pre-motor) is more rapid in crossing from one side to the other. As to the issue of lateral asymmetries in the CUD, the results of Expt. 3 have also shown that asymmetries arise only in tasks requiring an IT and therefore cannot depend upon additive hemispheric effects.

Adult↗

PubMed1993

The reach to grasp movement of blind subjects.

The importance of vision for the processing and coordination of the transport and manipulation components of a reach to grasp movement was assessed. Four blind volunteers (two men, two women; aged 25-40) were compared with matched control groups: (1) blindfolded and (2) full vision. Subjects reached 20 or 30 cm for a large or small diameter (6 cm or 0.7 cm, respectively) cylinder. For condition 1 trials they were given no instruction as to the type of grasp to adopt; for condition 2 they were instructed to consistently use a precision grip; while for condition 3 they were required to use whole had prehension. Blind subjects demonstrated a double grip pattern and either a low-velocity phase (20 cm) or a double transport movement (30 cm). However, their pattern of prehension with respect to intrinsic (size) and extrinsic (distance) cylinder properties was similar to that of the control groups. Grip aperture was appropriately scaled and, when greater precision was required, deceleration time was prolonged. Temporal coupling was evident between the two components. It was concluded that experience of vision is not necessary for the coordination or patterning of the basic reach to grasp movement. It does allow, however, for a movement consisting of only one opening and closing of the hand.

Acceleration↗

PubMed1993

Aging and selective attention in arithmetic calculations.

The aim of the present work was to test the effect of aging on the capacity to perform and validate simple arithmetic calculations. Two experimental groups, eight young and eight old subjects, performed a set of three tasks (A,B,C), requiring different amounts of attentional resources. In test A, the subjects knew in advance the type of operation to be validated; in test B the subjects had to validate items of four randomly mixed operation types; in test C the subjects could use an informative cue which signalled in advance the kind of operation to be performed. The cue was true in 70% of items (valid trials) and false in 30% (invalid trials). The results confirmed a slowing down of cognitive processes in old people that partially depended on task complexity. Differently from young, old subjects could not use the informative cue to orient attention toward specific arithmetic facts: actually in test C the difference between invalid vs. valid trials does not reach statistical significance.

Adult↗

PubMed1992

[Recall of the proper names of persons: effect of age and the modality of access].

Aging is associated with phenomena of slowing down of cognitive processes and impairment of neuropsychological performances. Elderly people also report difficulty in the retrieval of proper names. Verbal fluency (VF) tests are particularly effective for the identification of even slight mental impairments. In this experiment we utilized the usual tests of VF for semantic categories and letters of the alphabet together with three new tests of VF for first names, differing in mode of access. The first mode was free recall, the second mode was semantic (first names beginning with a particular letter), and the third mode was autobiographical (first names of relatives). There were 3 experimental groups: young people with high education level, elderly people with high education level and elderly people with low education level. The aim of our work was to verify whether aging modifies the performance in the VF tests, particularly in the three first name VF tests. No difference was found between the groups of young and elderly people with high education level. The comparison between the two groups of elderly people, with high and low education level, showed that significant differences were present in some but not in all of the VF tests. While the two groups clearly differed in semantically oriented tests, no difference could be detected in the test oriented to episodic memory. This result seems to be inconsistent with the hypothesis that aging affects mainly episodic memory.

Adult↗

PubMed1991

[Orientation of attention in the visual space].

The display was composed of four boxes, horizontally aligned above the fixation point. In Experiment I, each box was cued by a digit shown at fixation. In Experiment II there were only two numeric cues, signalling the inner or the outer boxes, depending on the experimental condition. The subject was instructed to orient attention to the cued box, and to respond to the imperative stimulus as fast as possible, wherever it appeared. By using four time interval (SOAs), we tried to determine the route covered by attention movements. In Experiment I, with the shortest SOA (100 msec), it was shown that attention does not reach the cued box through a direct path. Rather it moves first on the inner boxes, thereafter focusing on the cued location. The same results were obtained in Experiment II, where the cue directed attention to the inner boxes. When the external boxes were cued, however, this trend was not observed.

Adult↗

PubMed1991

[Orientation strategy implicit in spatial attention].

In this experiment, two rows of four boxes, one above and the other below the fixation point, were displayed on a computer monitor. A cognitive numeric cue indicated one of the four external boxes, where the attention was to be directed. Stimuli, however, could occur in any of the eight boxes. The subject was instructed to respond to the imperative stimulus as fast as possible, regardless of its location. Four time intervals between cue and stimulus presentation (SOAs) were employed in order to disclose the route along which attention is moved. With the shortest SOA (100 msec) an indication that attention movements follow the cartesian/orthogonal axes was shown.

Adult↗

PubMed1991

[Effect of age on the orientation of attention: effect of changing the interval between signal and stimulus].

The purpose of the experiment was to examine the effect of aging on spatial attention. One of two possible locations, horizontally arranged, was cued. The subject had to respond to the onset of a visual stimulus, wherever it appeared. The task demand was to orient attention to the stimulated location before producing a response, or to reorient it if the position is not the cued one. Younger and older adults showed the same response pattern, despite the overall slowing down of response presented by the latter.

Adolescent↗

PubMed1985

Influence of sialic contents on the chemiluminescent response of human leucocytes to group B streptococci.

The sialic acid content in reference strains of various Group B streptococci serotypes was studied before and after serial passages in mouse to enhance the virulence. The passages in mouse strongly increased the sialic acid content but the neuraminidase treatment reduced the to comparable values in reference and in virulent strains. The chemiluminescent response of human polymorphonuclear leucocytes to different GBS strains was higher for reference strains and lower for virulent strains. Sialic acid removal by neuraminidase increased the chemiluminescent response in virulent and in reference strains. Negative correlation between sialic acid content and chemiluminescence was demonstrated in strains of the same serotype, before and after passages in mouse and neuraminidase treatment for types Ic, II and III but no correlation was found considering the sialic acid content in strains belonging to different serotypes.

Animals↗