Are all left bundle branch blocks the same? Myocardial mechanical implications by cardiovascular magnetic resonance.

AIMS: Left bundle branch block (LBBB) is usually associated with structural myocardial diseases progressively leading to left ventricular (LV) dysfunction. We sought to determine the mechanical implications of LBBB (as defined based on Strauss' criteria) by Cardiovascular Magnetic Resonance (CMR). METHOD AND RESULTS: We included consecutive patients referred to CMR to assess the structural cause of LBBB. CMR scans consisted of cine, stress perfusion, and late gadolinium enhancement (LGE) sequences. Myocardial deformation was assessed by tissue tracking analysis; LGE was quantified using the full width at half maximum method. We included 86 patients [63% male, 70 years (60-72)] with mean QRS duration 150 ± 13 msec. A structural disease was identified on CMR in 53% of patients (ischemic heart disease, IHD, 31%; non-ischemic heart disease, NIHD, 22%), while LBBB-related septal dyssynchrony (SD) was the only abnormality in 47%. LGE was found in 42% of patients. LVEF and myocardial deformation were impaired. Despite similar ECG characteristics, myocardial strain differed significantly between IHD, NIHD and SD patients, and patients with SD showed less impaired myocardial deformation. Indexed LV end-systolic volume and LGE extent were independently associated with impaired strain. CONCLUSIONS: Patients with LBBB show different structural and mechanical properties, and LGE extent has an unfavourable effect on myocardial mechanics.

Morphogenesis of the pancreas of Bufo bufo during metamorphosis.

Histology and immunohistochemical reactivity (IR) toward insulin, glucagon, somatostatin14, and pancreatic polypeptide were investigated in the pancreas and in other tissues of Bufo bufo during metamorphosis. Insulin IR cells appeared at the very beginning of metamorphosis among exocrine pancreatic cells rich in yolk platelets, not completely arranged in acini. Less than 1 week later, glucagon, somatostatin14, and pancreatic polypeptide IR cells also appeared. At metamorphic climax, both endocrine and exocrine tissues of the pancreas underwent extensive degeneration, mainly via apoptotic cellular death. At this time the number of IR cells and the intensity of immunohistochemical reactions decreased for all the hormones tested. Pancreatic reorganization began at the end of the climax.

[Morphological effects of pituitary gonadotropic hormones on the development of chick embryo testes and ovaries in organ cultures (author's transl)]. / Effets morphologiques des hormones hypophysaires gonadotropes sur le développement de testicules et d'ovaires d'embryons de poulet en culture organotypique.

Organ cultures of sexually differentiated gonads were studied in order to determine the role played by the gonadotropic hormones LH and FSH in the development of chick embryo testes and ovaries. The groups of gonads examined were: A) gonads of normal 18-day-old embryos; B) gonads explants on standard medium; C) standard medium + LH (60 microgram/ml); D) standard medium + FSH (60 microgram/ml); E) standard medium + LH (20 microgram/ml) + FSH (20 microgram/ml). After culture for eight days, the testicular explants from the control group B demonstrated gonocytes in the cortical epithelium, which was stratified and contained no connective tissue, together with a reduction of the diameter of the medullary cords and stromal tissue in relation to 18-day-old embryos. In groups C, D, and E, the cortical epithelium contained no gonocytes and there was differentiation into an albugineous type of connective tissue. The diameter of the cords and the extent of the stroma was similar to that of normal embryos in groups C and D, but were reduced in group E. The cortex in the control group B ovarian explants was thicker than in normal living embryo's ovaries and somatic cells were rarely seen: cords containing gonocytes and lacunae had developed in the medulla. True ovotestes were sometimes observed. The thickness of the cortex and the morphology of the medulla in group C were similar to those of the control group explants. The FSH in the culture medium in groups D and E, caused a reduction in the thickness of the cortex and the development of lacunae.