Oxidation and cleavage of 3-aminopyridine adenine dinucleotide phosphate with periodate

Treatment of 3-aminopyridine adenine dinucleotide phosphate with sodium periodate in the neutral pH resulted in oxidation of the ribose linked to 3-aminopyridine and cleavage of the dinucleotide into adenosine- and 3-aminopyridine-containing moieties. Separation of these moieties was afforded by thin-layer chromatography, high-performance liquid chromatography, and fast protein liquid chromatography. From fast atom bombardment mass spectra and nuclear magnetic resonance spectra, the adenosine-containing moiety was identified as 2'-phosphoadenosine 5'-phosphate while the aminopyridine moiety was present in a mixture of the hydrated 3-aminopyridine mononucleotide/nucleoside dialdehyde. Separation of the completely oxidized product by Pharmacia fast protein liquid chromatography gave three major peaks corresponding to 2'-phosphoadenosine 5'-phosphate, 2'-phosphoadenosine 5'-diphosphate and oxidized 3-aminopyridine nucleoside, with minor amount of oxidized 3-aminopyridine mononucleotide. Thus the oxidized 3-aminopyridine adenine dinucleotide phosphate was shown to cleave by two pathways: it may either undergo beta-elimination to give 2'-phosphoadenosine 5'-diphosphate and oxidized 3-aminopyridine nucleoside; or the phosphodiester linkage may be hydrolyzed to give 2'-phosphoadenosine 5'-phosphate and oxidized 3-aminopyridine mononucleotide. The latter compound may further undergo beta-elimination and eventually give oxidized 3-aminopyridine nucleoside. Hydrolysis could be prevented by storing the sample as lyophilized powder, while beta-elimination was diminished by lowering the storage temperature. We found that the lyophilized powder of oxidized 3-aminopyridine adenine dinucleotide phosphate can be stored at -50 degrees C for several months with minimum decomposition.     

Binding of antibodies against high and low molecular weight cytokeratin proteins in the human placenta with special reference to infarcts, proliferation and differentiation processes

Recent immunocytochemical studies have shown that placental villous trophoblasts contain the high molecular weight cytokeratin (CK) proteins 5/6 and 17. In the case of CK 17, trophoblastic immunostaining was positive in villi covered by fibrinoid. CKs 5/6 and 17 are expressed by hyperproliferative cells. The aim of this investigation was to examine the location of these CKs in placental infarcts, known to be demarcated by fibrinoid and hyperproliferative trophoblasts. The results were compared with those obtained by immunostaining against Ki-67, tenascin and α1-, α6- and β1- integrins, which are involved in cell proliferation, differentiation and regenerative processes. Furthermore, the expression of the single CKs 7, 8, 10, 13, 14, 18 and 19 was investigated by immunocytochemistry and immunoblotting. While low and high molecular weight CKs were present in villous and extravillous trophoblasts, only low molecular weight CKs were detected in vascular and extravascular placental smooth muscle cells. Placental infarcts revealed different immunoreactivities in the infarct margin and centre: high molecular CKs, tenascin, Ki-67 and oncofoetal fibronectin predominated in the infarct margin, low molecular CKs, fibrin and integrins in the centre. The expression of tenascin and a defined change in the expression of CK 17 indicates villous repair and hyperproliferative mechanisms in placental infarcts. This revised version was published online in November 2006 with corrections to the Cover Date.     

Suppressed Retinal Degeneration in Aged Wild Type and APPswe/PS1ΔE9 Mice by Bone Marrow Transplantation

Alzheimer''s disease (AD) is an age-related condition characterized by accumulation of neurotoxic amyloid β peptides (Aβ) in brain and retina. Because bone marrow transplantation (BMT) results in decreased cerebral Aβ in experimental AD, we hypothesized that BMT would mitigate retinal neurotoxicity through decreased retinal Aβ. To test this, we performed BMT in APPswe/PS1ΔE9 double transgenic mice using green fluorescent protein expressing wild type (wt) mice as marrow donors. We first examined retinas from control, non-transplanted, aged AD mice and found a two-fold increase in microglia compared with wt mice, prominent inner retinal Aβ and paired helical filament-tau, and decreased retinal ganglion cell layer neurons. BMT resulted in near complete replacement of host retinal microglia with BMT-derived cells and normalized total AD retinal microglia to non-transplanted wt levels. Aβ and paired helical filament-tau were reduced (61.0% and 44.1% respectively) in BMT-recipient AD mice, which had 20.8% more retinal ganglion cell layer neurons than non-transplanted AD controls. Interestingly, aged wt BMT recipients also had significantly more neurons (25.4%) compared with non-transplanted aged wt controls. Quantitation of retinal ganglion cell layer neurons in young mice confirmed age-related retinal degeneration was mitigated by BMT. We found increased MHC class II expression in BMT-derived microglia and decreased oxidative damage in retinal ganglion cell layer neurons. Thus, BMT is neuroprotective in age-related as well as AD-related retinal degeneration, and may be a result of alterations in innate immune function and oxidative stress in BMT recipient mice.     

Characterization of the gut microbiota of migratory passerines during stopover along the northern coast of the Gulf of Mexico

Although the gut microbiota is known to provide many beneficial functions to animal hosts, such as aiding in digestion, fat metabolism, and immune function, relatively little is known about the gut microbiota of passerines. Gut microbes may have both beneficial and detrimental impacts on the fitness of migratory passerines; however physiological and morphological changes associated with prolonged migratory flight may cause disruptions of the stable microbiota and potentially a loss of function. Fecal samples were collected from Swainson's thrushes Catharus ustulatus and gray catbirds Dumetella carolinensis immediately after crossing the Gulf of Mexico during spring migration and before crossing during fall, and microbiota communities were analyzed using next‐generation sequencing. Microbiota communities were generally dominated by Firmicutes and Proteobacteria, with potential pathogens as well as potentially beneficial bacteria identified in all birds. Energetic condition of migrants was not significantly related to overall microbiota community structure though it cannot be conclusively stated that migratory flight does not impact the microbiota. Spring and fall migrants showed clear differences in microbiota communities, indicating that environmental factors influence the gut microbiota of these species more than host genetics.     

Distinct mechanisms account for β-amyloid toxicity in PC12 and differentiated PC12 neuronal cells

Whether reactive oxygen species (ROS) mediate beta-amyloid (A beta) neurotoxicity remains controversial. Naive PC12 cells (PC12) and nerve growth factor-differentiated PC12 cells (dPC12) were used to study the role of ROS in cell death induced by A beta(25-35). The viability of PC12 and dPC12 cells decreased by 30-40% after a 48-hour exposure to 20 microM A beta(25-35). Microscopic examination showed that A beta(25-35) induced necrosis in PC12 cells and apoptosis in dPC12 cells. Vitamin E (100 microM) and other antioxidants protected PC12 cells, but not dPC12 cells, against the cytotoxic effect of A beta(25-35). Since H(2)O(2) has been proposed to be involved in A beta toxicity, the effects of H(2)O(2) on PC12 and dPC12 cells were studied. Differentiated PC12 cells appeared to be significantly more resistant to H(2)O(2) than naive PC12 cells. These data suggest that ROS may mediate A beta(25-35) toxicity in PC12 cells but not in dPC12 cells. Because the intracellular levels of ROS were elevated during the differentiation of PC12 cells, the baseline levels of ROS in these two model cell types may determine the intracellular mediators for A beta(25-35) toxicity. Therefore, the protective effects of antioxidants against A beta may depend upon the redox state of the cells.     

Salvia miltiorrhiza inhibits intimal hyperplasia and monocyte chemotactic protein-1 expression after balloon injury in cholesterol-fed rabbits

Antioxidants that prevent low density lipoproteins (LDL) from oxidation may inhibit atherosclerosis and post-angioplasty restenosis. Salvia miltiorrhiza (SM) has been shown to inhibit LDL oxidation and reduce atherosclerosis in cholesterol-fed rabbits. The effects of SM on neointimal hyperplasia and monocyte chemotactic protein-1 (MCP-1) expression after balloon injury were studied. Male New Zealand white rabbits were fed a 2% cholesterol diet together with daily SM (4.8 gm/kg body wt.) treatment (SM; n=10) or without SM as a control (C; n=9) for 6 weeks. Probucol-treated (0.6 gm/kg body wt.) rabbits (P; n=9) were used as a positive control group. A balloon injury of the abdominal aorta was performed at the end of the third week. Aortas were harvested at the end of 6 weeks. The plasma cholesterol levels were lowered in SM group. The neointimal hyperplasia in abdominal aortas was significantly inhibited in SM group [neointima/media area ratio: 0.63+/-0.05 (SM) versus 0.78+/-0.05 (C); P < 0.05] and in P group [0.45+/-0.02 (P) versus 0.78+/-0.05 (C); P < 0.05] when compared with C group. SM treatment significantly reduced MCP-1 mRNA and protein expression in balloon-injured abdominal aorta. These inhibitory effects on intimal response after balloon injury might be attributed to antioxidant capacity and cholesterol lowering effect of SM. SM treatment may offer some protection against post-angioplasty restenosis.     

A salvianolic acid B-rich fraction of Salvia miltiorrhiza induces neointimal cell apoptosis in rabbit angioplasty model

Apoptosis has been suggested to participate in stabilizing cell number in restenosis. Salvia miltiorrhiza (SM) Bunge which is a Chinese herb widely used for the treatment of cardiovascular disorders contains a potent antioxidant, Salvianolic acid B. To determine whether the antioxidant affects vascular apoptosis, the present study examined the frequency of apoptotic cell death in atherosclerotic plaques and in restenotic lesions of cholesterol-fed rabbits. New Zealand White rabbits were treated with a normal diet (normal), a 2% cholesterol diet (HC), a 2% cholesterol diet and endothelial denudation (HC-ED), a 2% cholesterol diet with 5% water-soluble extract of SM (4.8 g/Kg B.W./day) and endothelial denudation (HC-ED-SM), or with a 2% cholesterol diet containing probucol (0.6 g/kg B.W./day) and endothelial denudation (HC-ED-probucol). Apoptosis and associated cell types were examined in serial paraffin sections by in situ terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling and immunohistochemistry. The expression of p53, an apoptosis-related protein, was also examined. Apoptosis was mainly detected in the neointima of the three groups with endothelial denudation. The percentage of apoptotic cells in SM-treated group (68.5+/-5.9%) was significantly higher than that of normal (0%), HC (1.9+/-1.2%), HC-ED (46.1+/-5.4%), and probucol-treated (32.8+/-3.9%) groups. The SM treatment markedly reduced the thickness of the neointima which was mainly composed of smooth muscle cells with few macrophages. In accordance with the apoptotic cell counts, positive immunoreactivity for p53 was observed in restenotic lesions from HC-ED, SM-treated and probucol-treated groups but not in the intima of the other two groups. These results suggest that the treatment with salvianolic acid B-rich fraction of SM induces apoptosis in neointima which in turn may help prevent the neointimal thickening.     

Obesity and Hepatic Steatosis Are Associated with Elevated Serum Amyloid Beta in Metabolically Stressed APPswe/PS1dE9 Mice

Diabesity-associated metabolic stresses modulate the development of Alzheimer’s disease (AD). For further insights into the underlying mechanisms, we examine whether the genetic background of APPswe/PS1dE9 at the prodromal stage of AD affects peripheral metabolism in the context of diabesity. We characterized APPswe/PS1dE9 transgenic mice treated with a combination of high-fat diet with streptozotocin (HFSTZ) in the early stage of AD. HFSTZ-treated APPswe/PS1dE9 transgenic mice exhibited worse metabolic stresses related to diabesity, while serum β-amyloid levels were elevated and hepatic steatosis became apparent. Importantly, two-way analysis of variance shows a significant interaction between HFSTZ and genetic background of AD, indicating that APPswe/PS1dE9 transgenic mice are more vulnerable to HFSTZ treatment. In addition, body weight gain, high hepatic triglyceride, and hyperglycemia were positively associated with serum β-amyloid, as validated by Pearson’s correlation analysis. Our data suggests that the interplay between genetic background of AD and HFSTZ-induced metabolic stresses contributes to the development of obesity and hepatic steatosis. Alleviating metabolic stresses including dysglycemia, obesity, and hepatic steatosis could be critical to prevent peripheral β-amyloid accumulation at the early stage of AD.