Chikara Mimata

Differential distribution and expressions of collagens in the cerebral aneurysmal wall

Abstract To investigate the role of collagens in the formation and rupture of cerebral aneurysms, we examined the distribution and synthesis of vascular collagens in the wall of normal human cerebral main trunks and of cerebral aneurysms using immunohistochemistry and in situ hybridization techniques. Fifteen cerebral aneurysmal walls were resected at operation; control cerebral main trunks were obtained from seven autopsy cases. Semiserial sections from the specimens were subjected to immunofluorescence and immunohistochemical staining with antibodies to collagen types I, III, IV, V, VI, desmin and α-smooth muscle actin. In addition, type III collagen mRNA was examined by in situ hybridization. Immunohistochemical study showed that all collagen types were grossly preserved in the aneurysmal wall, although the distribution patterns were different for each collagen. The distribution of major fibrillar collagen types I and III was more diffuse and homogeneous in the luminal layer of the aneurysmal wall than the media of the control artery, although the intensity of immunohistochemical staining was weaker in the abluminal layer of the aneurysmal wall than the adventitia of the control artery. Collagen types IV and V were distributed more sparsely in the luminal layer of the aneurysmal wall than the media of the control artery. Collagen type VI was noted in the luminal as well as the abluminal layer of the aneurysmal wall, whereas it was located exclusively in the adventitia of the control artery. In situ hybridization showed that the signal for collagen type III mRNA on fibroblastic and smooth muscle cells was higher in the aneurysmal walls than the control arteries, suggesting up-regulation of type III collagen transcription in the cerebral aneurysmal wall. The study of the distribution and synthetic regulation of various types of collagen in the aneurysmal wall may be essential for understanding the formation of the aneurysmal wall and its protection against enlargement or rupture.

Occipital Neuralgia As a Presenting Symptom of Cervicomedullary Dural Arteriovenous Fistula

Dural arteriovenous fistulas (DAVFs) at the cervicomedullary junction are rare and have a wide variation in presentation. We report a case of occipital neuralgia (ON) as a rare presenting symptom of cervicomedullary DAVF causing intramedullary hemorrhage at the C1 level. It is important to consider the underlying causes of ON, and precise neurological examinations and radiological evaluations are needed.

Glioblastoma with an intratumoral feeding-artery aneurysm

We report a patient with recurrent glioblastoma, in whom serial magnetic resonance angiography (MRA) demonstrated gradual enlargement of an artery feeding the tumor and the development of an intratumoral aneurysm that led to intratumoral hemorrhage. The literature contains no previous reports that clinically document intratumoral aneurysms arising from these vessels. This is a rare case of glioblastoma in which the association of an intratumoral feeding-artery aneurysm, whose rupture led to intratumoral bleeding, was documented by serial MRA imaging and follow-up.

Differential expressions of collagen types IV, III, and I during the development of invasive trophoblasts in rats

We examined the differential expressions of collagen types IV, III, and I in the developing feto‐maternal placental tissue of pregnant rats by a combination of in situ hybridization and immunohistochemistry. At day 9.5 of gestation, polygonal invasive cytotrophoblasts from the ectoplacental cone, which was modifying the maternal central artery, revealed intensely expressed α1(IV) and α1(III) collagen mRNAs. The localization patterns of these translated products, collagen type IV and procollagen type III, were slightly different in the invasive cytotrophoblasts. Collagen type IV densely deposited intracellularly and intercellularly in the maternal central artery and in the thickened basement membranes of the cytotrophoblasts. However, expression of α1(I) collagen mRNA and procollagen type I was hardly detectable in the cytotrophoblasts. At day 13 of gestation, a high level of α1(IV) collagen mRNA was expressed in the cytotrophoblastic cell layer (trophospongium) and in the invasive large cytotrophoblasts. A moderate level of α1(III) collagen mRNA was also expressed mainly in the cytotrophoblasts, while α1(I) collagen mRNA was expressed at very low levels. Interestingly, procollagen type III failed to show linear immunoreactivity in the subepithelial extracellular matrix beneath the maternal artery with the invasive cytotrophoblasts. Additional quantitative analyses of these type IV, III, and I collagen mRNA levels in in situ hybridization experiments between several cell types also revealed significant differences individually. Electron microscopic study detected no cross‐striated collagen fibers in the thickened basement membrane‐like structures adjacent to the invasive cytotrophoblasts. Fibrillar and basement membrane collagen gene expressions, their protein syntheses, and the processing of these procollagens seem to be developmentally regulated in the invasive cytotrophoblasts during the organization of feto‐maternal placental tissue. The remodeling of the maternal central artery by the invasive cytotrophoblasts is important for ensuring the adequate blood supply to the developing placenta and fetus.