Biomedical subjects

Catherine Fallet

Publications and source records attributed to Catherine Fallet.

3 recordsLinked to original sources

PubMed2004

Development of the human motor-related thalamic nuclei during the first half of gestation, with special emphasis on GABAergic circuits.

This study analyzed the expression of differentiation markers (Calbindin D28K: CaBP; parvalbumin: PARV; calretinin: CalR), gamma-aminobutyric acid (GABA) markers (GABA, glutamic acid decarboxylases: GAD65, GAD67; and GABA transporters: GAT1, GAT3), and other markers (neurotensin: NT, and neurofilament-specific protein: SMI32) in the human thalamus at 8-23 gestation weeks (g.w.), focusing on the motor-related nuclei. From 8-13 g.w. mainly CaBP was expressed in the cells while fiber bundles traversing the thalamus in addition to CaBP expressed all GABA markers except GAD67. CaBP and PARV expression patterns in different nuclei changed over the time course studied, whereas NT was expressed consistently along the anterior-lateral curvature of the thalamus. CalR and SMI were detectable at 23 g.w. in the ventral parts of the dorsal thalamus. Most remarkably, punctate GAD65 immunoreactivity in the neuropil was confined to the nigro- and pallidothalamic afferent receiving nuclei from 16 to about 21 g.w., overlapping with that of CaBP in some of these nuclei (subdivisions of the ventral anterior and mediodorsal nuclei) and with PARV in others (centromedian nucleus). During this period, GAD65 immunoreactivity can be considered a marker of the basal ganglia afferent receiving territory in the motor thalamus. GAD67-positive local circuit neurons were first detected at 12-13 g.w. in the thalamic nuclei outside the basal ganglia afferent receiving territory. In the ventral anterior and centromedian nuclei, GAD-containing local circuit neurons were not conspicuous even at 22-23 g.w. The cells of the reticular nucleus expressed GAD67 and PARV from 12 g.w. on starting in the lateral-posterior regions. By 23 g.w., both markers were expressed in about two-thirds of the nucleus except for its most medial-anterior part. The results imply spatially and temporally differential expression of GABA and differentiation markers in the developing human thalamus.

Biomarkers↗

PubMed2003

Synemin expression in developing normal and pathological human retina and lens.

Synemin (Syn) is an intermediate filament (IF) protein. To gain insight into a morphogenetic role of Syn, we have studied its expression patterns in the developing human retina and lens and compared it with those of other IF proteins. In addition, we have tested Syn expression in fetuses (23 and 28 weeks) affected by Walker-Warburg syndrome (WWS), Meckel syndrome, and trisomy 13. In the retina, Syn expression starts in the nerve fiber and ganglion cell layers (NFL and GCL) at 15 weeks, remains there in up to 20 weeks, and spreads to other layers and may be colocalized with vimentin, GFA, or neurofilaments in the subsequent 16 weeks. This expansion of Synemin expression from 20 to 28 weeks is not observed in WWS in which Syn immunoreactivity in NFL is reduced and Vim expression is increased. Changes are seen in Syn or vimentin expressions in the retinae of 23-week-old Meckel syndrome or 28-week-old trisomy 13 fetuses. Syn expression in the lens is, at first (16 weeks), uniformly distributed, becoming stronger in the epithelium of the anterior part at 25 weeks and later. As in the retina, Syn expression in lens is also selectively affected in WWS. The colocalization of Synemin with vimentin, GFA, or NF supports the idea that Syn is a key cross-linking protein that connects different cytoskeletal structures. Moreover, stagnant Syn expression in WWS retina and lens reinforces the notion of a significant role of this protein in morphogenesis.

Fetal Diseases↗

PubMed2002

Isolated non-compaction of the myocardium diagnosed in the fetus: two sporadic and two familial cases.

Isolated non-compaction of the ventricular myocardium is characterized by numerous and prominent trabeculations and deep intertrabecular recesses. This rare disease is due to an arrest of myocardial morphogenesis. Most cases, when seen in children, are associated with obstructive malformations. Isolated non-compaction is even rarer in childhood, and affects predominantly the myocardium of the left ventricle. Morbidity and mortality resulting from cardiovascular complications is high. In most cases, transplantation is the final option. To our knowledge, this rare cardiac malformation has yet to be diagnosed in the fetus. We report here two sporadic cases, one male and one female, and 2 familial cases, both male, which were diagnosed prenatally and followed by fetal echocardiography. Our study indicates that isolated non-compaction is a primary disorder of early fetal development. Our cross-sectional echocardiographic examinations revealed a fetal cardiomyopathy, with prominent and numerous trabeculations and deep intertrabecular recesses of the myocardium at the apex of the ventricles. In contrast with postnatal experience, we found isolated non-compaction mostly in the right ventricle. Systolic dysfunction was found in all cases. The diagnosis was confirmed by histology in 3 fetuses dying with cardiac failure, and by postnatal cross-sectional echocardiography in the fetus who survived. Two male fetuses belonged to a family in which 3 individuals were subsequently found to be affected. We discuss the issues of prenatal diagnosis, natural history, and myocardial histology.

Adolescent↗