Biaxial mechanical properties of the inferior vena cava in C57BL/6 and CB-17 SCID/bg mice.

Multiple murine models have proven useful in studying the natural history of neovessel development in the tissue engineering of vascular grafts. Nevertheless, to better understand longitudinal changes in the biomechanics of such neovessels, we must first quantify native tissue structure and properties. In this paper, we present the first biaxial mechanical data for, and nonlinear constitutive modeling of, &QJ;the inferior vena cava from two models used in tissue engineering: wild-type C57BL/6 and immunodeficient CB-17 SCID/bg mice. Results show that inferior vena cava from the latter are significantly stiffer in the circumferential direction, both materially (as assessed by a stored energy function) and structurally (as assessed by the compliance), despite a lower intramural content of fibrillar collagen and similar wall thickness. Quantifying the natural history of neovessel development in different hosts could lead to increased insight into the mechanisms by which cells fashion and maintain extracellular matrix in order to match best the host stiffness while ensuring sufficient vascular integrity.

Undiminished regulatory T cells in the thymus of patients with myasthenia gravis.

OBJECTIVE: The thymus has been implicated as a possible site of origin that triggers autoimmunity in myasthenia gravis (MG). Although several groups have suggested that the decrease in the number of regulatory T (Treg) cells contributes to the onset of MG, the exact role of Treg cells in MG remains unclear. To address this point, we examined the number and distribution of Treg cells in a large number of patients with MG. METHODS: Immunohistofluorescence analysis of Foxp3 along with CD4 and CD8 was performed in thymic sections of MG (+) (n = 24) and MG (-) patients (n = 27). Circulating CD4(+)CD25(+) cells in the peripheral blood of patients with MG (n = 15) and age-matched healthy subjects (n = 15) were also analyzed. RESULTS: Foxp3(+)CD4(+)CD8(-) cells were predominantly found in the thymic medulla and their number declined with age. There was no significant difference in the number or the distribution of Foxp3(+)CD4(+)CD8(-) cells in the thymus between MG (+) and MG (-) patients. The number of circulating CD4(+)CD25(+) cells in the peripheral blood of patients with MG was not significantly altered compared to that in healthy subjects. CONCLUSION: The cellularity of Treg cells in the thymus and circulation is not diminished in patients with myasthenia gravis.

Transcriptional regulation of fatty acid cyclooxygenases-1 and -2.

Transcriptional regulation of fatty acid cyclooxygenase isozymes (COX-1 and COX-2) were studied using two cell lines. A rapid and transient induction of COX-2 was observed by the addition of tumor necrosis factor alpha (TNF alpha) to murine osteoblastic cells MC3T3-E1. Possible involvement of NF kappa B and NF-IL6 as transcription factors was shown by deletion experiments using a luciferase reporter gene. COX-1 induction by a phorbol ester was demonstrated along with differentiation of human megakaryoblastic cells CMK to megakaryocytes.

Subacute dementia with necrotising encephalitis selectively involving the fornix and splenium. Retrograde development of Alzheimer's neurofibrillar tangles in the subiculum.

An elderly woman developed subacute progressive dementia with predominant impairment in recent memory and CT findings indicating an enhancing lesion near the splenium of the corpus callosum. Autopsy four months after the onset of the symptoms revealed necrotising encephalitis selectively involving the bilateral fornices and the adjacent splenium. Degeneration was marked in the contiguous right fimbria hippocampi. Particularly numerous Alzheimer's neurofibrillar tangles (NFTs) were present in the right subiculum, while they were scattered in Sommer's sectors and parahippocampal gyri and were practically nonexistent elsewhere. Senile plaques were rare. Electron microscopy disclosed that the right subicular tangles were composed mostly of 15-nm straight tubules which were also frequently observed in the myelinated axons. Since the major projection fibers to the fornix originate in the subiculum, the distinctive pattern of NFT distribution might be derived from the retrograde neuronal changes secondary to the fornix-fimbria lesion. This case represents a rare form of amnesia-dementia confirmed anatomically to have been caused by fornix lesions.