Pattern formation of reaction-diffusion system having self-determined flow in the amoeboid organism of Physarum plasmodium

The amoeboid organism, the plasmodium of Physarum polycephalum, behaves on the basis of spatio-temporal pattern formation by local contraction-oscillators. This biological system can be regarded as a reaction-diffusion system which has spatial interaction by active flow of protoplasmic sol in the cell. Paying attention to the physiological evidence that the flow is determined by contraction pattern in the plasmodium, a reaction-diffusion system having self-determined flow arises. Such a coupling of reaction-diffusion-advection is a characteristic of the biological system, and is expected to relate with control mechanism of amoeboid behaviours. Hence, we have studied effects of the self-determined flow on pattern formation of simple reaction-diffusion systems. By weakly nonlinear analysis near a trivial solution, the envelope dynamics follows the complex Ginzburg-Landau type equation just after bifurcation occurs at finite wave number. The flow term affects the nonlinear term of the equation through the critical wave number squared. Contrary to this, wave number isn't explicitly effective with lack of flow or constant flow. Thus, spatial size of pattern is especially important for regulating pattern formation in the plasmodium. On the other hand, the flow term is negligible in the vicinity of bifurcation at infinitely small wave number, and therefore the pattern formation by simple reaction-diffusion will also hold. A physiological role of pattern formation as above is discussed.Comment: REVTeX, one column, 7 pages, no figur

Induction of apoptosis and secondary necrosis in rat dorsal root ganglion cell cultures by oxidized low density lipoprotein

Neural cell degeneration underlies central and peripheral nervous system disorders. In this study we examined the influence of oxidized low density lipoprotein (Ox-LDL) on rat dorsal root ganglion (DRG) cells in culture. Methods used were cell morphology, lactate dehydrogenase (LDH) release, the TUNEL-reaction and DNA fragmentation. Exposure of DRG cells to Ox-LDL for 24 h led to elevation of LDH in the culture medium; short term exposure (4 h) induced apoptosis, evidenced by DNA fragmentation and a positive TUNEL-reaction. DRG cells modified LDL in the presence of Cu2+ to mildly oxidized and to a small extent to fully oxidized forms; these in situ-generated LDL oxidation products were strongly toxic. These results suggest that Ox-LDL is a neurotoxin; it initiates apoptotic cell injury which progresses to necrosis and cell death

Induction of apoptosis and secondary necrosis in rat dorsal root ganglion cell cultures by oxidized low density lipoprotein

Neural cell degeneration underlies central and peripheral nervous system disorders. In this study we examined the influence of oxidized low density lipoprotein (Ox-LDL) on rat dorsal root ganglion (DRG) cells in culture. Methods used were cell morphology, lactate dehydrogenase (LDH) release, the TUNEL-reaction and DNA fragmentation. Exposure of DRG cells to Ox-LDL for 24 h led to elevation of LDH in the culture medium; short term exposure (4 h) induced apoptosis, evidenced by DNA fragmentation and a positive TUNEL-reaction. DRG cells modified LDL in the presence of Cu2+ to mildly oxidized and to a small extent to fully oxidized forms; these in situ-generated LDL oxidation products were strongly toxic. These results suggest that Ox-LDL is a neurotoxin; it initiates apoptotic cell injury which progresses to necrosis and cell death

Distribution of extracellular matrix proteins in pterygia: an immunohistochemical study

Naib-Majani W, Eltohami I, Wernert N, et al. Distribution of extracellular matrix proteins in pterygia: an immunohistochemical study. GRAEFES ARCHIVE FOR CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY. 2004;242(4):332-338.Purpose: This study was carried out to monitor the expression of extracellular matrix proteins (ECMs) and metalloproteinases (MMPs) in pterygial tissue. Methods: Twenty primary nasal pterygia were studied by indirect routine immunohistochemistry using 13 different primary antibodies against 8 ECMs (five collagens, fibronectin, heparan sulfate, and laminin) fibroblast growth factor (bFGF), von Willebrand factor (vWF), and 3 MMPs (8, 9, and 13). Secondary antibodies were fluoresceinated. Intensity of reaction on individual sections was graded semi-quantitatively. Results: No expression of collagens I, II, and VII was found. Antibodies against collagen III reacted strongly positively (+++) with the entire pterygial stroma. Collagen IV expression was strongly positive in the wall of pterygial blood vessels, moderately positive (++) in the epithelial basement membrane, and only weakly positive (+) all over the stroma. Antibodies against fibronectin reacted moderately positively with stroma, blood vessel walls and epithelial basement membrane. Heparan sulfate was strongly expressed in the blood vessel walls and epithelial basement membrane. Antibodies against bFGF reacted only with pterygial epithelium. Laminin was strongly expressed in blood vessel wall, moderately (++) in the epithelial basement membrane and weakly over the entire stroma. vWF was strongly positive (+++) with pterygial blood vessel walls. Antibody reactions for MMPs differed. It was strong with pterygial epithelium (MMPs 8, 9 and 13), strong to moderate with pterygial stroma (MMPs 8 and 13 versus 9), and absent to weak with pterygial vascular walls (MMPs 8 and 13 versus 9). Conclusions: This study documents the presence of several ECMs but excludes the expression of others in pterygial tissues. The results especially indicate an active involvement of MMPs 8, 9 and 13 in the pathogenesis of pterygia