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Biomedical subjects

M Robin

Publications and source records attributed to M Robin.

At least 37 records · Page 2Linked to original sources
PubMed1995

Unusual transformation of the 3-hydroxy-picolinoyl residue of pristinamycin IA.

Pristinamycin IA was modified in a two-step procedure to give original derivatives possessing a tricyclic nucleus (8a, 8b, 8c) or a substituted pyrrole ring (10a, 10b) in place of the natural exocyclic 3-hydroxy-picolinoyl residue. This transformation involved firstly preparation of pyridinium betaines 5 from pristinamycin IA and secondly a 1-3 dipolar cycloaddition between 5 and N-substituted maleimides or diethyl acetylenedicarboxylate. The compounds obtained were evaluated as antibacterial agents alone and in association with pristinamycin IIA.

Alkylation↗
PubMed1995

[A therapeutic approach using dental implants in an irradiated area. The experiences of the René Huguenin Center].

A therapeutic trial was conducted with six patients who were in remission after cancer therapy for at least two years. Twenty-four implants were performed in irradiated maxillary bone after local and general paraimplantation preparation using adjuvant hyperbaric oxygenotherapy. All implants integrated the bone within a minimal delay of nine months. All patients were fitted with a removable dental prosthesis which was anchored magnetically or with implant conjunction bars. Despite the limited number of implants and the short observation period, the results have been promising, in agreement with previous reports. These findings emphasize the importance of adjuvant hyperbaric oxygenotherapy and the need for good conditions in paraimplantation tissue. Although this technique demonstrates that dental implantation in irradiated tissue is possible, the risk of secondary failure has not been determined. In strictly selected cancer patients with reasonably healthy irradiated tissue, implantation can be proposed by a fully multidisciplinary team of specialists.

Aged↗
PubMed1993

The effect of aspartate hydroxylation on calcium binding to epidermal growth factor-like modules in coagulation factors IX and X.

Hydroxylation of aspartic acid to erythro-beta-aspartic acid (Hya) occurs in epidermal growth factor (EGF)-like modules in numerous extracellular proteins with diverse functions. Several EGF-like modules with the consensus sequence for hydroxylation bind Ca2+, and it has therefore been suggested that the hydroxyl group is essential for Ca2+ binding. To determine directly the influence of beta-hydroxylation on calcium binding in the EGF-like modules from coagulation factors IX and X, we have now measured calcium binding to both the fully beta-hydroxylated and the non-beta-hydroxylated modules of the two proteins. At low ionic strength, the Hya-containing module of factor X has a slightly higher Ca2+ affinity, but at physiological salt concentrations this difference is no longer significant for either factor IX or X. Analysis of the 1H NMR chemical shift differences between the hydroxylated and nonhydroxylated factor X modules show that hydroxylation has no effect on the domain fold. Furthermore, measurements on factor IX show that hydroxylation has no effect on the Ca2+/Mg2+ specificity of the ion binding site. We conclude that the hydroxyl group is not a direct ligand for the calcium ion in these EGF-like modules, nor is it essential for high-affinity Ca2+ binding.

Amino Acid Sequence↗
PubMed1992

Alpha-cobratoxin: proton NMR assignments and solution structure.

The solution structure of alpha-cobratoxin, a neurotoxin purified from the venom of the snake Naja naja siamensis, at pH 3.2 is reported. Sequence-specific assignments of the NMR resonances was attained by a combination of a generalized main-chain-directed strategy and of the sequential method. The NMR data show the presence of a triple-stranded beta-sheet (residues 19-25, 36-41, and 52-57), a short helix, and turns. An extensive number of NOE cross peaks were identified in the NOESY NMR maps. These were applied as distance constraints in a molecular modeling protocol which includes distance geometry and dynamical simulated annealing calculations. A single family of structures is observed which fold in such a way that three major loops emerge from a globular head. The solution and crystal structures of alpha-cobratoxin are very similar. This is in clear contrast to results reported for alpha-bungarotoxin where significant differences exist.

Amino Acid Sequence↗
PubMed1992

Effects of early mother-twin relationships from birth to age 3, on twin bonding.

Findings from an earlier phase of this research project clearly pointed to the mother's psychological adaptation inherent to the specificities of triadic interaction. Mothers' attitudes were classified in a typology ranging from "early twinness" where the two babies are treated as though they were a single unit, to attempt to create two dyadic relationships. The current program deals with the effects of the type of parent-child relationship at one year on the emergence of twin bonding. Sixty-eight families of twins (26MZ, 24DZ same sex, 18DZ different sex) are followed up from birth to the age of 3 using a method based on clinical interviews, videotaped observations, and questionnaires. The data cover mothers' rearing attitudes towards organization of babycare and outward signs of twinness, maternal representations of the relationship between the twins and observation of the children's interaction in a standardized game situation. The findings are discussed in terms of zygosity, and parental SCS.

Attitude↗
PubMed1992

Patent paraumbilical vein: anatomic and hemodynamic variants and their clinical importance.

Fifty-five of 353 patients with suspected portal hypertension studied with Doppler sonography had a patent paraumbilical vein. Of these 55 patients, 39 had the classic intrahepatic venous circulation found in Cruveilhier-Baumgarten syndrome: hepatopetal flow in all segmental portal veins and hepatofugal flow leaving the liver in a paraumbilical vein in the falciform ligament to join veins of the anterior abdominal wall. Sixteen patients had variants of the classic pattern: Flow in one or more segmental portal veins of the left lobe or the entire liver was hepatofugal. In addition, new venous channels connecting the left portal vein with the extrahepatic paraumbilical vein were found. Assessment of liver function with the Pugh score showed severe impairment in the majority of patients with a patent paraumbilical vein. Patients with the classic intrahepatic circulation had smaller esophageal varices than those with hemodynamic or anatomic variants. The presence of a patent paraumbilical vein did not prevent formation of esophageal varices in the patients studied.

Adolescent↗
PubMed1991

Maternal reactions to the birth of triplets.

This study examines the reactions of 14 women to the birth of triplets. Home interviews and observations were conducted at 4 months and 1 year after the birth. The findings indicate that the triplet situation constitutes a real source of psychological stress for the women in this study. Reactions depend on two factors: individual makeup, in that some women become depressed whereas others develop defenses, and amount of support from family and friends. These variables, along with mothers' ability to overcome phantasms of abnormality generated by the exceptionality of a multiple maternity, serve to define a set of predictors of good/poor prognosis for the establishment of triplet-mother relationships.

Adaptation, Psychological↗
PubMed1991

Forms of family reorganization following the birth of twins.

A survey questionnaire of 200 families with 2-month-old twins assesses the economic, social and psychological impact of the arrival of twins on family life. The study shows the extent of material difficulties mothers of twins are confronted with, and the ways they cope with them--recourse to mother's helpers, assistance from the father and other members of the family (analyzed in terms of parity and socioeconomic/cultural status), twincare organization strategies, and impact on the decision to stop working. The findings provide an overall picture of the real situation, a necessary prerequisite to an understanding of psychological problems.

Adult↗
PubMed1990

Rapid determination and NMR assignments of antiparallel sheets and helices of a scorpion and a cobra toxin.

An NMR method is described which should provide a rapid means for determining and assigning antiparallel sheets and helices in small proteins. It begins by locating apparent NOESY crosspeaks which suggest the presence of the secondary structure; this is followed by searches for MCD patterns (Englander & Wand (1987) Biochemistry 22, 5953) which are characteristic of these structures. As a result, only spin-systems of the amino acids within the secondary structure need to be defined. A triple-stranded, antiparallel sheet and a helix have been found and assigned for both alpha-cobratoxin and the scorpion toxin AaH III.

Animals↗
PubMed1989

[Therapeutic approach to post-radiation xerostomia. A reservoir prosthesis and an artificial salivary gland].

Radiation-induced xerostomia is an incapacitating sequela of salivary gland irradiation in patients receiving tumoricidal X-ray therapeutical doses for cancer of the upper respiratory and gastrointestinal tracts. All stimulant type therapeutics available are powerless to bring back wetness into the mouth of patients with asialia. Replacement therapy constitutes the only alternative for symptomatic treatment. Artificial salivary gland sprays have a proven unsustained, short-lasting efficacy. The administration of an oral mucine-containing salivary emollient solution drip, presented either in the form of an oral or external container, constitutes an original symptomatic treatment regimen, the efficacy of which has been established. The authors here review the concept and methodology of their palliative treatment protocol against chronic asialia.

Denture Design↗
PubMed1988

Mother-twin interaction during early childhood.

The components of a research program focusing on early mother-twin interaction is described. Preliminary data obtained from a questionnaire at two months post term, cross-sectional observations at the age of one year, a follow-up study involving home observation and parental interviews from birth to the age of 3, point to the specificity of this triadic situation. During the first months of life, the burden of material tasks and the increase in baby care leave little time for starting a relationship based on pleasure or play. The impossibility of responding simultaneously to the needs of two babies and the difficulty of forming relationships on an individual basis foster early concerns for egalitarianism. The degree of physical resemblance between the babies creates the problem of differentiating them. To tell twins apart, mothers rapidly tend to rely on behavioral characteristics to which they attribute a genetic basis. In contrast, differences in development between the babies that introduce the eventuality of the dominance of one of the twins are often denied. In this highly specific situation, mothers arrive at personal solutions of adjustment over the first 3 years, manifest in a certain number of psychological and educational attitudes. Analysis of these maternal attitudes may help to shed light on some of the features of later psychoemotional development in twins.

Adaptation, Psychological↗