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Biomedical subjects

A Sanson

Publications and source records attributed to A Sanson.

15 recordsLinked to original sources
PubMed1992

Peptide secondary structure induced by a micellar phospholipidic interface: proton NMR conformational study of a lipopeptide.

The conformational change of the model peptide Ac-K-G-R-G-D-G-amide induced by a phospholipidic interface was investigated by proton nuclear magnetic resonance (1H NMR). In aqueous solution, the free peptide is highly flexible and disordered, even in the presence of deuterated dodecyl-phosphocholine (DPC-d38) micelles which mimic a membrane interface. The lipopeptide, obtained by grafting a lipid anchor [2,3-dipalmitoyl-D-(+)-glyceric acid] to the lysine side chain of the peptide, was studied by standard 2D 1H NMR spectroscopy combined with distance geometry and simulated annealing calculations. When anchored to a micelle interface, the peptide acquires a definite turn (II/I') conformation. We were also able to describe precisely the conformation of the diacylglyceric fragment of the lipopeptide in a lipid environment and to establish the average orientation of the peptide segment with respect to the micelle surface.

Amino Acid Sequence↗
PubMed1992

Transient versus stable behavior problems in a normative sample: infancy to school age.

Identified 3 subgroups of children from a prospective longitudinal study of temperament and development: (a) those with stable, (b) transient, or (c) no-behavior problems, as rated by mothers across the toddler, preschool, and preparatory school grade periods. Children with stable behavior problems were particularly characterized by more difficult temperament, mothers' overall perception of the child as difficult, and aggressive behavior in the 2- to 4-year age period. Group differences were linear rather than categorical with transient behavior problem children showing a lesser degree of difficulty. In a second study where more comprehensive child and family measures were available, temperament was again an important discriminator, with Vineland Adaptive Behavior Composite Score, mothers' overall perception of the child's temperament, and maternal psychological health and stress factors also more adverse for the stable group. However, correct classification of the members of these groups using a combination of the above variables was not impressive.

Child↗
PubMed1992

[The monitoring of plasma digoxin levels during acute digitalis poisoning treated with Fab anti-digoxin fragments].

Life-threatening digitalis intoxication is treated using digoxin specific antibody fragments (Fab) that bind and inactivate the drug. The free digoxin serum concentration could be useful in the management of Fab-treated patients, but the standard methods of measurement can be clinically misleading because Fab anti-digoxin interferes with digitalis immunoassay measurements. A case involving Fab therapy of a digoxin overdosed patient, in which two laboratory methods gave very different results, is reported. The radioimmunologic assay (RIA), widely used in laboratories, yielded high values without relation to true serum free digoxin concentration. On the contrary, the recently introduced fluoroenzymatic sequential immunoassay (FEIA), which accurately measures free glycoside concentration, was a valuable aid in monitoring Fab treatment. Therefore, cardiologists' knowledge of a possible interference of specific anti-digoxin fragment treatment with many immunoassays may greatly enhance the rational management of these patients.

Acute Disease↗
PubMed1991

Echocardiographic findings in one case of Swyer-James syndrome.

The Swyer-James syndrome is an uncommon disease. The main finding is a hyperlucent lung with small hilar shadows on chest x-ray. This is due to a decrease in pulmonary artery size at its origin and in the number and size of pulmonary branches. Pulmonary angiography is the standard method for diagnosis. We report a case of a unilateral hyperlucent lung in which the diagnosis was suggested by an echocardiographic evaluation.

Adult↗
PubMed1991

Risk indicators: assessment of infancy predictors of pre-school behavioural maladjustment.

The prediction of later outcome from factors present in infancy has been an ongoing concern, with difficult temperament frequently being posited as one important risk factor. Using data from a longitudinal study of a large representative sample of children, and a categorical approach to analysis, a set of infancy risk factors covering within-child, environmental and relationship variables was related to behavioural and emotional adjustment at 4-5 years. Single risk factors, including difficult temperament, resulted in only modest increases in the prevalence of later maladjustment. However, certain combinations of risk factors were associated with markedly increased prevalence rates. The results indicate the cumulative effects of risk factors, and the need to consider temperament within a contextual framework.

Affective Symptoms↗
PubMed1991

Temperament and behavior of preterm infants: a six-year follow-up.

To test the commonly held premise that prematurity is a risk factor for problems of behavior and social interaction, as well as cognitive and physical development, temperament and behavior of children born preterm and full-term control subjects were compared at five separate time periods from infancy through early school age. All the preterm infants (n = 126) of a representative group of infants enrolled in a longitudinal study (n = 2443) were surveyed at 4 to 8 months corrected age. Subsamples of the group were studied further in successive years as young toddlers (n = 65), older toddlers (n = 60), preschoolers (n = 84), and at early school age (n = 81). At each period there were no differences between those studied and those not studied on socioeconomic status, gestational age, sex, or birth order. Parental ratings of temperament and behavior were used at appropriate ages: the Revised Infant Temperament Questionnaire, the Toddler Temperament Scale, the Childhood Temperament Questionnaire, Behaviour Checklist, Preschool Behaviour Questionnaire, and Rutter's Childhood Behaviour Questionnaire (CBQ), as well as mother's overall rating of temperament. In infancy there were no significant differences on temperament dimensions, clinical temperament categories, or parental ratings of individual or composite behaviors between the preterm and full-term groups. For toddlers, temperament scores were similar for the two groups but preterm subjects were significantly more likely (P less than .01) to have an easy temperament and less likely to have a difficult temperament. There were no differences on any of the other temperament or behavior ratings.(ABSTRACT TRUNCATED AT 250 WORDS)

Child Behavior↗
PubMed1990

Assessment of temperament in the toddler age group.

We used the Toddler Temperament Scale with large representative samples of younger (mean age = 20.5 months; N = 1188) and older (mean age = 35.4 months; N = 1360) Australian toddlers. There were significant sex differences on 6 of the temperament dimensions for the young group, and on 5 of the 9 dimensions for the older group. Older boys were also more likely to be categorized clinically as having a "difficult" temperament and less likely to have an "easy" temperament. Each group was divided into quartiles according to socioeconomic status. For the younger toddlers there were significant differences in 3 of 9 temperament dimensions, and for the older group there were significant differences in 7 of 9 dimensions. Groups with higher socioeconomic status had temperament ratings which were more likely to make them easier to manage, and to be categorized clinically as having an easy temperament, but toddlers with low socioeconomic status were more likely to have a difficult temperament. There were significant differences in temperament dimension scores between Australian toddlers and those studied in an American setting. These results indicate that toddler temperament ratings differ according to age, sex, social class, and cultural context. Great caution needs to be taken in interpreting individual temperament profiles utilizing comparison data obtained from different sociocultural settings. Future temperament "norms" may need to specify characteristics of the group of children from which they were derived to allow more valid comparisons.

Age Factors↗
PubMed1978

Variations in apolipoproteins B and A1 during the course of myocardial infarction.

The plasma apolipoproteins B and A1, and plasma lipids and lipoproteins, were studied in fifteen patients with acute myocardial infarction. In the days immediately after acute infarction there was a decrease in total cholesterol, low density lipoprotein-cholesterol, total apolipoprotein-B, low density lipoprotein apolipoprotein-B and high density lipoprotein apolipoprotein A1. High density lipoprotein-cholesterol remained unchanged. In the same period the total triglycerides, very low density lipoprotein-protein, very low density lipoprotein-cholesterol, very low density lipoprotein apolipoprotein-B and very low density lipoprotein apolipoprotein A1 were increased. A reduction of the apolipoprotein ratio CII/CIII occurred after the acute phase. After 25--30 days all these values regained their baseline values.

Aged↗
PubMed1977

Fatty acids diffusion in lecithin multilayers: hydration and PH effects.

The diffusion of the sodium salt of monocarboxylic fatty acids, from formate to stearate, has been studied as a function of water content and pH in lecithin--water lamellar phases. Evolution of the diffusion coefficients with increasing chain length reflects the different localizations of fatty acids in the system. From formate to butyrate, which are mainly restricted to the hydrophilic layer of the phase, diffusion rates decrease rapidly. From butyrate to stearate, fatty acids (anchored at the hydrophilic--lipophilic interface) undergo lateral diffusion and then the decrease of D with increasing chain length is much slower. The diffusion of stereate is already comparable to the diffusion of the lecithin molecule itself. The diffusion rates strongly depend upon phase hydration and pH: it is shown that both parameters control the fatty acid ionization. The variations in diffusion rates observed may be ascribed to the fact that, depending upon their state of ionization, fatty acids assume a different localization and therefore experience different interactions in the lamellar system.

Biological Transport↗
PubMed1976

An ESR study of the anchoring of spin-labeled stearic acid in lecithin multilayers.

In egg lecithin-water lamellar phases, spin-labeled stearic acid gives two superimposed ESR spectra which are only well resolved when the temperature is greater than 30 degrees C. These two spectral components are attributed to the dissociated and non-dissociated forms of the fatty acid carboxylic group, anchored at two different positions in the polar interface constituted by the hydrated lipid polar heads. Results on such interactions of other functional groups (spin-labeled fatty ester and fatty alcohol) are also presented.

Binding Sites↗
PubMed1976

An ESR study of the hydration steps of lecithin multilayers.

A spin-labeled stearic acid and other spin-labeled molecules have been used for an ESR study of the hydration process of the egg lecithin lamellar phase for water concentrations, CW greater than 10%. Two hydration steps are found for CW approximately 20% and CW congruent to 30%, in good agreement with results of the literature. To explain discontinuities in the behavior of three spin-labeled molecules at CW congruent to 20%, a conformational change of the phosphatidylcholine polar head and a phase transition in the polar interface are proposed.

Binding Sites↗
PubMedDate not supplied

[Treatment of unstable angina with dipyridamole combined with low doses of aspirin. A multicenter pilot double-blind controlled study].

In order to assess the usefulness of a combination of low-dose aspirin (25 mg b.i.d.) with dipyridamole (200 mg b.i.d.) in the prevention of major coronary events in patients with acute unstable angina, we performed a prospective, double-blind, placebo-controlled study involving 88 consecutive patients admitted to three Hospital Departments of Cardiology. The patients entered the study as soon as possible after hospital admission, and were treated and followed up to one year. There was no appreciable difference in side effects and adverse reactions between the treatment and control group. The incidence of cardiac death and/or nonfatal myocardial infarction during the whole period of observation was 14% (6/44) in the treatment group and 25% (11/44) in the placebo group by "intention-to-treat" analysis; 16% (4/25) and 32% (10/31), respectively, by "drug-efficacy" analysis (p = 0.21 by Fisher's exact test, non significant difference). However, when considering the only events occurred in the first month (2/44 in the treatment group and 9/44 in the placebo group, amounting to 4.5 and 20 percent, respectively), the combination of dipyridamole with low-dose aspirin reached a statistically significant protective effect (p = 0.04). The results of this pilot study provide strong evidence for a beneficial effect of the regimen tested in patients with acute unstable angina, at least in the first weeks of treatment, while at the same time suggesting a safe alternative for patients with contraindications to higher doses of aspirin.

Adult↗