Detection of genomic deletions of PKP2 in arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited myocardial disease that predominantly affects the right ventricle and is associated with ventricular arrhythmias that may lead to sudden cardiac death. Mutations within at least seven separate genes have been identified to cause ARVC, however a genetic culprit remains elusive in approximately 50% of cases. Although negative genetic testing may be secondary to pathogenic mutations within undiscovered genes, an alternative explanation may be the presence of large deletions or duplications involving known genes. These large copy number variants may not be detected with standard clinical genetic testing which is presently limited to direct DNA sequencing. We describe two cases of ARVC possessing large deletions involving plakophilin‐2 (PKP2) identified with microarray analysis and/or multiplex ligation‐dependent probe amplification (MLPA) that would have been classified as genotype negative with standard clinical genetic testing. A deletion of the entire coding region of PKP2 excluding exon 1 was identified in patient 1 and his son. In patient 2, MLPA analysis of PKP2 revealed deletion of the entire gene with subsequent microarray analysis demonstrating a de novo 7.9 Mb deletion of chromosome 12p12.1p11.1. These findings support screening for large copy number variants in clinically suspected ARVC cases without clear disease causing mutations following initial sequencing analysis.     

Episodic variations of prolactin, thyroid-stimulating hormone, luteinizing hormone, melatonin and cortisol in infertile women with subclinical hypothyroidism

Preliminary data have suggested that female infertility due to corpus luteum insufficiency may be caused by subclinical hypothyroidism [exaggerated thyroid-stimulating hormone (TSH) response to thyrotrophin- releasing hormone (TRH) stimulation]. L-Thyroxine supplementation has been recommended to achieve pregnancies in subclinical hypothyroid women. This controlled study was carried out in order to investigate the biochemical diagnosis of subclinical hypothyroidism as a possible infertility factor. Five infertile patients (aged 25-36 years) with subclinical hypothyroidism (n = 4, stimulated TSH >20 microU/ml) or primary hypothyroidism (n = 1) and five healthy controls (aged 22-39 years) with normal thyroid function (stimulated TSH <15 microU/ml), regular cycles and no history of infertility were studied in the early follicular phase. In the pre-study evaluation, eight of 23 volunteers (34.8%) had to be excluded because of subclinical hypothyroidism with stimulated TSH values (TSHs) >15 microU/ml. Cycle function of patients and controls was compared by the method of LH pulse pattern analysis. Therefore blood samples were drawn every 10 min during a 24 h period. Sleep was recorded from midnight to 7 a.m. Repetition of the TRH tests at the end of the 24 h blood sampling period confirmed the difference in stimulated TSH values of the two study groups. Pulse analysis for luteinizing hormone (LH), TSH and prolactin showed no differences between patients and controls for pulse frequency, amplitude, height, length, area under curve (AUC) and the 24 h mean. Even the hypothyroid patient had a normal LH pulse pattern. Additional measurement of melatonin in pooled sera every 30 min gave the well-documented diurnal profiles during day and night for both groups. Patients had significantly higher melatonin values at seven time points during the night. Peaks for LH, TSH, prolactin and cortisol were correlated with the sleep stages wake, rapid eye movement, 1 + 2 and 3 + 4. We concluded that corpus luteum insufficiency in female infertility cannot be explained by subclinical hypothyroidism and thus should not be treated with L-thyroxine for fertility reasons.      

Assisted reproductive technology and complex chromosomal rearrangements: the limits of ICSI

Complex chromosomal rearrangements are very rare events in the human population. According to our knowledge on the consequences of simple reciprocal translocations for male fertility, translocations involving three or more chromosomes are thought to lead to severe reproductive impairments in terms of meiotic disturbance or chromosomal imbalance of gametes. We report the case of a 48 year old man whose sperm count revealed either oligozoospermia (<10(3) spermatozoa/ml) or azoospermia. He was referred to the laboratory for in-vitro fertilization after intracytoplasmic sperm injection. Cytogenetic investigations showed a complex chromosomal rearrangement involving firstly a translocation between the short arm of chromosome 7 and the long arm of chromosome 13 and secondly a translocation between the short arm of the same chromosome 13 and the short arm of chromosome 9. Diagnosis was ascertained by fluorescence in-situ hybridization and staining of the nucleolar organizer regions. Theoretical study of the translocated chromosomes predicted a 'chain' configuration of the hexavalent at the pachytene stage of meiosis. In all, 32 modes of segregation were considered and only one resulted either in a normal or a balanced gamete karyotype. Genetic counselling and choice of appropriate artificial reproduction technique are discussed.      

The GAP-related domain of tuberin, the product of the TSC2 gene, is a target for missense mutations in tuberous sclerosis

Tuberous sclerosis is an autosomal dominant trait in which the dysregulation of cellular proliferation and differentiation results in the development of hamartomatous growths in many organs. The TSC2 gene is one of two genes determining tuberous sclerosis. Inactivating germline mutations of TSC2 in patients with tuberous sclerosis and somatic loss of heterozygosity at the TSC2 locus in the associated hamartomas indicate that TSC2 functions as a tumour suppressor gene and that loss of function is critical to expression of the tuberous sclerosis phenotype. The TSC2 product, tuberin, has a region of homology with the GTPase activating protein rap1GAP and stimulates the GTPase activity of rap1a and rab5a in vitro. Here we show that the region of homology between tuberin and human rap1GAP and the murine GAP mSpa1 is more extensive than previously reported and spans approximately 160 amino acid residues encoded within exons 34-38 of the TSC2 gene. Single strand conformation polymorphism analysis of these exons in 173 unrelated patients with tuberous sclerosis and direct sequencing of variant conformers together with study of additional family members enabled characterisation of disease associated mutations in 14 cases. Missense mutations, which occurred in exons 36, 37 and 38 were identified in eight cases, four of whom shared the same recurrent change P1675L. Each of the five different missense mutations identified was shown to occur de novo in at least one sporadic case of tuberous sclerosis. The high proportion of missense mutations detected in the region of the TSC2 gene encoding the GAP-related domain supports its key role in the regulation of cellular growth.      

Method of quantitative anatomical study of the dorsal neck muscles

Summary Biomechanical models of the cervical spine require knowledge of the position, size and orientation of the individual muscles that act on the cervical spine. We have developed a technique to stereometrically measure anatomical specimens. The apparatus is composed of three graduated metallic rods, which slide along a fixed support. This method is accurate to map the anatomy of individual muscles and provides quantitative data on their lines of action. Results are obtained from one specimen. The computer processing of the collected data allows formulation of a three-dimensional model of the neck muscles in man.

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Méthode d'étude anatomique quantitative des muscles de la nuqueEtude préliminaire

Résumé Pour élaborer un modèle biomécanique de la colonne cervicale, il faut connaître la position, la taille et l'orientation des différents muscles du cou. Nous avons mis au point une méthode de mesure stéréométrique sur des sujets anatomiques. L'appareil est composé de 3 axes métalliques gradués qui coulissent sur un support fixe. Cette technique permet une étude anatomique précise de chacun des muscles de la nuque, fournissant des données quantitatives sur les différents faisceaux ou lignes d'action. Les résultats sont obtenus sur un sujet. Leur traitement informatique permettra l'élaboration d'un modèle mathématique tridimensionnel des muscles du cou chez l'homme.

     

The morphological differentiation of the internal sphincter muscle of the anus in the human embryo and fetus (26.01.1990)

Conclusion The opening of the anal canal appears to be the factor which initiated the differentiation of the sphincter apparatus.The internal sphincter m. of the anus is entirely composed of smooth muscle as distinct from the striated fibers of the m. puborectalis, and the external sphincter which is a mixture of smooth and striated fibers (of skeletal type). It develops in the terminal part of the internal circular layer of the rectal m., outside which are longitudinal fibers which descend early to form the external sphincter (beginning around the third month).This study shows that the internal sphincter is scarcely evident before 12 SA. Thus continence between 10 and 12 SA (after the closure of the anal membrane) is closely related to the other components of the sphincter apparatus. On the other hand, the internal sphincter has become well formed after 28 to 30 SA and then plays a direct role in maintaining continence.     

Impact of calcium entry blockers on glomerular injury in experimental hypertension

Summary A major problem for patients with kidney disease and their physicians is that most chronic renal diseases progress to global glomerular sclerosis and end-stage renal failure. Studies in experimental models of hypertension and renal insufficiency have advanced our understanding of the pathogenesis of progressive kidney damage. In a number of settings, sclerosis has been related to the presence of intrarenal hypertension, a consequence of the hemodynamic adaptation to a reduction in the number of functioning nephrons. A growing body of evidence also supports the hypothesis that kidney and glomerular hypetrophy constitute an independent risk factor for glomerular sclerosis. Recent studies suggest that calcium antagonists can reduce glomerular injury in experimental hypertension. Renal protection may be related to the ability of these agents to inhibit compensatory renal growth.     

Hepatosplenic T-cell lymphoma: sinusal/sinusoidal localization of malignant cells expressing the T-cell receptor gamma delta

Peripheral T-cell lymphomas consist of a clinically heterogeneous group of malignant disorders whose immunophenotype usually corresponds to that of normal mature T cells. We describe and correlate the clinical, histopathologic, phenotypic, and genotypic findings in two patients with malignant lymphoma presenting with hepatosplenic disease. The morphologic pattern of lymphoma was that of a sinusal/sinusoidal infiltration in spleen, marrow, and liver. This morphologic characteristic was associated with the presence of a productive clonal rearrangement of the T-cell receptor (TCR) delta gene. Lymphoma cells expressed a CD3-TCR-gamma delta- phenotype. They were also double negative (ie, CD4-CD8-) and lacked the CD5 and CD7 antigens. In one patient, tumor progression was associated with phenotypic changes that resulted in a CD3-TCR-gamma delta- phenotype with the same delta-gene rearrangement as initially. These observations suggest the existence of a new type of peripheral T-cell lymphoma characterized by its hepatosplenic presentation, and by the sinusal/sinusoidal tropism and the TCR-gamma delta phenotype of the malignant cells.     

Comparing human and mouse salivary glands: A practice guide for salivary researchers

Mice are a widely utilized in vivo model for translational salivary gland research but must be used with caution. Specifically, mouse salivary glands are similar in many ways to human salivary glands (i.e., in terms of their anatomy, histology, and physiology) and are both readily available and relatively easy and affordable to maintain. However, there are some significant differences between the two organisms, and by extension, the salivary glands derived from them must be taken into account for translational studies. The current review details pertinent similarities and differences between human and mouse salivary glands and offers practical guidelines for using both for research purposes.