Cross-Sectional Imaging of Third Molar-Related Abnormalities.

Third molars may be associated with a wide range of pathologic conditions, including mechanical, inflammatory, infectious, cystic, neoplastic, and iatrogenic. Diagnosis of third molar-related conditions can be challenging for radiologists who lack experience in dental imaging. Appropriate imaging evaluation can help practicing radiologists arrive at correct diagnoses, thus improving patient care. This review discusses the imaging findings of various conditions related to third molars, highlighting relevant anatomy and cross-sectional imaging techniques. In addition, key imaging findings of complications of third molar extraction are presented.

NADPH oxidase inhibitor, apocynin, restores the impaired endothelial-dependent and -independent responses and scavenges superoxide anion in rats with type 2 diabetes complicated by NO dysfunction.

OBJECTIVE: We investigated the effect of apocynin, an NADPH oxidase inhibitor, in the impairment of vascular responses in Otsuka Long-Evans Tokushima Fatty (OLETF) rats (type 2 diabetic rat model) with or without (w/wo) N-nitro-l-arginine methyl ester treatment. METHODS: Male OLETF and littermate Long-Evans Tokushima Otsuka (LETO) (28 weeks old) rats were separated as follows: LETO w/wo apocynin (Gp C, Gp C-apo), OLETF w/wo apocynin (Gp DM, Gp DM-apo) and OLETF plus l-nitro arginine acetate ester w/wo apocynin (Gp DMLN, Gp DMLN-apo). Five days after, peritoneal macrophages were stimulated with thioglycolate. Two days after, they were evaluated. RESULTS: Plasma glucose and lipid levels remained unchanged. Acetylcholine-induced nitric oxide-dependent (NO-dependent) relaxation and nitroglycerin-induced NO-independent relaxation were improved in the Gp DMLN-apo, compared with that in Gp DMLN. Tone-related basal NO release and plasma NO(2) (-) and NO(3) (-) tended to be lower in Gp DM and Gp DMLN groups. The increased amount of superoxide anion released from macrophages in Gp DM and Gp DMLN was restored by apocynin. Intimal thickening was observed in aortae of Gp DM and Gp DMLN animals; however, there was little in aortae of Gp DM-apo and Gp DMLN(-) apo rats. Increased tumour necrosis factor-alpha (TNF-alpha) in the Gp DM and Gp DMLN was also restored by apocynin treatment. CONCLUSION: Apocynin restores the impairment of endothelial and non-endothelial function in diabetic angiopathy in OLETF without changing plasma glucose and lipid levels. NO and O(2) (-) may play a role in this process by decreasing TNF-alpha levels.

Estrogen prevents destabilization of endothelial nitric oxide synthase mRNA induced by tumor necrosis factor alpha through estrogen receptor mediated system.

17beta-estradiol up-regulates endothelial nitric oxide synthase (eNOS) expression in cultured endothelial cells. To clarify the role of mRNA stabilization in upregulation of eNOS expression, endothelial cells were incubated with actinomycin D as transcriptional inhibitor. Up to 10 hours incubation with 17beta-estradiol alone did not affect significantly the stability of eNOS mRNA. As tumor necrosis factor-alpha (TNF-alpha) is associated with the progression of atherosclerosis, we examined the effect of 17beta-estradiol on eNOS mRNA destabilization with TNF-alpha. After 10 hours co-incubation with TNF-alpha, relative intensity of eNOS mRNA decreased to 50% of the intensity at the start time of incubation, however, it remained significantly 1.6 times in the presence of 17beta-estradiol. This inhibitory effect of 17beta-estradiol was abolished by the treatment of estrogen receptor antagonist, ICI 182,780. This is the first finding that 17beta-estradiol stabilizes eNOS mRNA destabilized by TNF-alpha through estrogen receptor mediated mechanism.

Temporal effects of 17beta-estradiol on caveolin-1 mRNA and protein in bovine aortic endothelial cells.

Endothelial nitric oxide synthase (eNOS) is regulated both by caveolin-1 and 17beta-estradiol (E(2)). Temporal relationships between effects of estrogen on caveolin-1 and nitric oxide (NO) are not known. Therefore, this study was designed to determine whether estrogen regulates caveolin-1 and, if so, whether such regulation corresponds to changes in nitrite/nitrate (NO(x)) production. Bovine aortic endothelial cells (BAECs) were cultured in the absence and presence of 17beta-estradiol or 17alpha-estradiol (10(-8) and 10(-10) M) for 12, 24, and 48 h. eNOS protein expression and NO(x) production increased significantly after 24 h but not after 12-h treatment with 17beta- and not 17alpha-estradiol. Both mRNA and protein for caveolin-1 were increased significantly only after 48-h treatment with E(2), but eNOS protein and NO(x) production were decreased compared with cells treated for 24 h. These increases in caveolin-1 were inhibited by the estrogen receptor antagonist ICI-182,780 (10(-6) M). Results of this study suggest that E(2) stimulates caveolin-1 transcription and translation through estrogen receptor-mediated mechanisms. The results further suggest that estrogen may indirectly regulate NO(x) through caveolin-1 expression, which inhibits eNOS catalytic activity.

Cerivastatin, a hydroxymethylglutaryl coenzyme a reductase inhibitor, improves endothelial function in elderly diabetic patients within 3 days.

BACKGROUND: The short-term effects of hydroxymethylglutaryl coenzyme A reductase inhibitors (statins) on endothelial function at doses that do not affect plasma lipid levels are not known. METHODS AND RESULTS: We investigated the short-term effects of cerivastatin, a hydroxymethylglutaryl coenzyme A reductase inhibitor, on endothelial function and endothelium-related products in elderly diabetic patients. Twenty-seven elderly diabetic patients (aged 69.3+/-3.4 years), with or without mild hypercholesterolemia, were enrolled in this study, which tested cerivastatin treatment (0.15 mg/d) for 3 days. Endothelium-dependent flow-mediated dilatation, endothelium-independent dilatation by nitroglycerin in the brachial artery, nitric oxide-related products (nitrite/nitrate and cGMP), endothelium-related products (von Willebrand Factor, soluble vascular cell adhesion molecule-1, and soluble intercellular adhesion molecule-1), and a marker of oxidant stress (8-isoprostane) were assessed. Levels of plasma lipids were not changed before and after treatment with cerivastatin. Flow-mediated dilatation was significantly increased by cerivastatin treatment, as were plasma nitrite/nitrate levels (from 16.9+/-3.4 to 22.0+/-3.7 micromol/L, P<0.05) and cGMP values. The percent of nitroglycerin-induced dilatation was not changed. Plasma concentrations of 8-isoprostane decreased, and levels of soluble vascular cell adhesion molecule also tended to decrease with cerivastatin. CONCLUSIONS: Improvement of endothelial function was in line with antiatherosclerotic effects. Cerivastatin improved impaired endothelial function in the short-term without affecting lipid profiles in elderly diabetic patients. This effect may be partly due to upregulation of endothelial nitric oxide synthase.

HMG-CoA reductase inhibitor stabilizes rabbit atheroma by increasing basal NO and decreasing superoxide.

Male rabbits fed a 0.5% cholesterol diet for 8 wk were divided into three groups. Group 1 was hypercholesterolemic; group 2 was fed a regular diet for an additional 12 wk; and group 3 was fed a regular diet with simvastatin (5 mg x kg(-1) x day(-1)). Simvastatin treatment reduced the atherosclerotic area and total and esterified cholesterol concentrations in the thoracic aorta. Tone-related basal nitric oxide (NO) release was highest in group 3. Acetylcholine-induced, NO-dependent relaxation was improved in group 3 compared with group 2. Amount of endothelial nitric oxide synthase (eNOS) mRNA in vessels increased in group 1, compared with normal aorta, and decreased in group 2; however, it did not decrease in group 3. The amount of O released from vessels increased in group 1 and group 2 compared with normal rabbits; however, it decreased in group 3, especially in the endothelial cells. Peroxynitrite determined by nitrotyrosine staining decreased in group 3. Additionally, the arteries of rabbits fed a regular diet with or without simvastatin were investigated. The aorta from simvastatin-treated group showed increase of tone-related basal NO release and eNOS mRNA and decrease of O release. Taken together, upregulation of eNOS and decrease of O treatment were observed in vivo in the process of the sufficient stabilization of atheroma following simvastatin.

A HMG-CoA reductase inhibitor possesses a potent anti-atherosclerotic effect other than serum lipid lowering effects--the relevance of endothelial nitric oxide synthase and superoxide anion scavenging action.

We have determined whether the anti-atherosclerotic effect of a 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase inhibitor (fluvastatin) is mediated through nitric oxide (NO) as well as affecting plasma lipids. NO related vascular responses, endothelial nitric oxide synthase (eNOS) mRNA and superoxide anion (O(2)(-)) release were examined in vascular walls of oophorectomized female rabbits fed 0.5% cholesterol chow for 12 weeks with or without fluvastatin (2 mg/kg per day). Serum lipid profile was not different between two groups. NO dependent responses stimulated by acetylcholine and calcium ionophore A23187 and tone related basal NO response induced by N(G)-monomethyl-L-arginine acetate (L-NMA); nitric oxide synthase inhibitor were all improved by fluvastatin treatment. Endothelium independent vasorelaxation induced by nitroglycerin was not different between the two groups of rabbits' arteries. Fluvastatin treatment increased cyclic GMP concentration in aorta of rabbits. eNOS mRNA expression and O(2)(-) release were measured in aorta using competitive reverse transcription-polymerase chain reaction (RT-PCR) and with lucigenin analogue, 2-methyl-3,7-dihydroimidazol [1,2-a]pyrazine-3-one (MCLA) chemiluminescence methods. eNOS mRNA in the endothelial cells of aorta was significantly up-regulated and O(2)(-) production was significantly reduced in fluvastatin treated rabbit aorta. Anti-macrophage staining area, but not anti-smooth muscle cell derived actin stained area in the aorta was also reduced by fluvastatin treatment. Conclusion, fluvastatin, a HMG-CoA reductase inhibitor, retards the initiation of atherosclerosis formation through the improvement of NO bioavailability by both up-regulation of eNOS mRNA and decrease of O(2)(-) production in vascular endothelial cells, and this means that part of the anti-atherosclerotic effect of fluvastatin may be due to nonlipid factors.

Up-regulation of endothelial nitric oxide synthase through beta(2)-adrenergic receptor--the role of a beta-blocker with NO-releasing action.

We determined the existence and role of beta(2)-adrenergic receptor in cultured BAECs through the effect of a beta-blocker having NO releasing action; 3,4-dihydro-8(2-hydroxy-3-isopropylamino)-propoxy-3-nitroxy-2H-1-benzopyran; nipradilol on eNOS and eNOS regulatory protein caveolin-1. beta(2) receptor exists in BAECs. eNOS mRNA and protein were up-regulated by its treatment whereas those of caveolin were not altered considerably. This eNOS up-regulatory action was abolished by beta(2) receptor antagonist, ICI-118551. Increase of NO metabolites, protein and mRNA of eNOS was also partially inhibited by co-treatment of NOS inhibitor, L-NA with nipradilol. This is the first investigation of the action of non-selective beta blocker on eNOS through beta(2) receptor. The drug increases NO on incubation with BAECs about 50% as a NO donor and about 50% as results of eNOS up-regulation.

Inhibition of inducible nitric oxide synthase gene expression by indomethacin or ibuprofen in beta-amyloid protein-stimulated J774 cells.

Recent studies show that a mononuclear phagocyte lineage, including microglia, plays a possible role in the pathogenesis of Alzheimer's disease through nitric oxide (NO)-mediated neurotoxicity. Epidemiological studies show that nonsteroidal anti-inflammatory drugs (NSAIDs) have a protective effect against Alzheimer's disease. Based on these observations, it has been hypothesized that an anti-Alzheimer's disease effect of NSAIDs could result from the inhibition of NO synthesis. We report here that indomethacin or ibuprofen dose-dependently reduce beta-amyloid protein and interferon-gamma-induced NO production, accompanied by an inhibition of inducible nitric oxide synthase mRNA expression in J774 cells, a murine macrophage cell line. Aspirin, however, does not produce such an effect, suggesting that the cyclooxygenases pathway is not involved in the inhibitory effects of NSAIDs on beta-amyloid protein and interferon-gamma-induced NO production in J774 cells.

Physiological concentration of 17beta-estradiol retards the progression of severe atherosclerosis induced by a high-cholesterol diet plus balloon catheter injury: role of NO.

The molecular mechanisms of the antiatherosclerotic effects of estrogen are not yet known. We evaluated the effects of 17beta-estradiol (E(2)) on high cholesterol diet- (HCD; standard diet and 1% cholesterol) and balloon injury-induced atherosclerosis in female New Zealand White rabbits. The abdominal aortas of 40 oophorectomized (Groups 1 through 5) and 8 nonoophorectomized (Group 6) rabbits were injured by balloon catheter, and the animals were then divided into the following groups and treated for 10 weeks: Group 1, standard diet; Group 2, standard diet plus a moderate dose of E(2) (100 microg x kg(-1) x d(-1)); Group 3, HCD; Group 4, HCD plus a moderate dose of E(2); Group 5, HCD plus a low dose of E(2) (20 microg x kg(-1) x d(-1)); and Group 6, HCD in nonoophorectomized rabbits. After the treatment phase, plasma E(2) was increased up to 282.2+/-45.5 pg/mL in Group 2, 263.0+/-41.5 pg/mL in Group 4, 87. 9+/-18.8 pg/mL in Group 5, and 45.6+/-7.3 pg/mL in Group 6. HCD-mediated increases in plasma lipid levels were not changed by E(2) treatment, whereas E(2) decreased the aortic intimal thickening in Group 2 animals compared with those in Group 1 and reduced atherosclerosis in the thoracic and abdominal aortas of Group 4, 5, and 6 rabbits compared with those in Group 3. E(2) restored the impaired abdominal aortic endothelium-dependent relaxation of balloon-injured and HCD-supplemented rabbits, and E(2) increased basal nitric oxide (NO) release. The basal NO-releasing effect showed a significant, inverse relation with the severity of atherosclerosis. Plasma E(2) concentration also showed a significant, inverse relation with atherosclerotic area. In conclusion, physiological concentrations of E(2) can retard the progression of severe atherosclerosis and stabilize atheromas induced by HCD and balloon injury. The retardation may be partially mediated by endothelial NO function in vessels treated with E(2).

Dehydroepiandrosterone retards atherosclerosis formation through its conversion to estrogen: the possible role of nitric oxide.

Dehydroepiandrosterone (DHEA) is speculated to have an antiatherosclerotic effect, although the mechanism of action remains unclear. The objective of the current study was to determine whether the antiatherosclerotic effect of DHEA is related to its conversion to estrogen and to define the role of nitric oxide (NO) in the antiatherosclerotic effect of DHEA. Forty-eight oophorectomized rabbits were divided into 5 groups and fed the following diets for 10 weeks: group 1, a regular rabbit diet plus 1% cholesterol (a high-cholesterol diet [HCD]); group 2, an HCD plus 0.3% DHEA; group 3, an HCD plus 0.3% DHEA and fadrozole (2.0 mg x kg(-1) x d(-1)), a specific aromatase inhibitor; group 4, an HCD plus 17beta-estradiol (20 microg x kg(-1) x d(-1)); and group 5, a regular diet. Atherosclerotic lesions, lipid deposition in aortic vessels, and basal and stimulated NO release were measured in the aforementioned groups of rabbits. NO release was measured by using an NO-selective electrode as well as by measuring vascular responses and the plasma NO metabolites nitrite and nitrate. The plasma total cholesterol level was increased, but there were no significant differences in lipid profile in the 4 groups of rabbits that were fed the HCD. The area occupied by atherosclerosis in the thoracic aorta was diminished by approximately 60% in the DHEA-treated rabbits (group 2) compared with the HCD group of rabbits (group 1); there was a corresponding 80% decrease in the estradiol group (group 4) but only a 30% decrease in the DHEA plus fadrozole group (group 3). In the aortas of rabbits from groups 1 and 3, the acetylcholine-induced and tone-related basal NO-mediated relaxations were diminished compared with those of the controls (group 5). However, these relaxations were restored in the aortas of group 2 and 4 rabbits, and an increase in NO release was observed in groups 2 and 4 compared with groups 1 and 3, as measured by an NO-selective electrode. Injection of neither solvent (20% ethanol/distilled water) nor fadrozole significantly affected the atherosclerotic area or the NO-related responses described above. We conclude that approximately 50% of the total antiatherosclerotic effect of DHEA was achieved through the conversion of DHEA to estrogen. NO may also play a role in the antiatherosclerotic effect of DHEA and 17beta-estradiol.

Expression of inducible nitric oxide synthase and Fas/Fas ligand correlates with the incidence of apoptotic cell death in atheromatous plaques of human coronary arteries.

It was recently reported that inducible nitric oxide synthase was expressed in advanced atheromatous plaques. So we investigated the effect of NO or peroxynitrite reactive product of NO or O(2)(-) released by iNOS induced in macrophages or T lymphocytes on inflammatory cells in atheromatous plaques of human coronary arteries by immunohistochemistry. We found that iNOS was expressed in T lymphocytes and macrophages in T lymphocytes and macrophages coexisted advanced atheromatous areas. Most of the smooth muscle cells are not coexisted with T lymphocytes. We could not find iNOS in those smooth muscle cells. Only a small number of iNOS-positive smooth muscle cells were found close to T lymphocytes and macrophages. Markers for apoptotic cells induced in situ terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) showed that many apoptotic T lymphocytes and macrophages existed near iNOS induced cells. Fas and Fas ligand were expressed in almost same areas that iNOS was expressed. By double-label immunostaining, Fas was expressed in T lymphocytes but Fas ligand was expressed in macrophages and in some T lymphocytes. These results suggest that NO from iNOS induces Fas and Fas ligand-mediated apoptosis and associates with regression of atherosclerosis. On the other hand, nitrotyrosine was detected wider areas than iNOS. So peroxynitrite from iNOS damages cells and tissues widely and may associate with progression of atherosclerosis. These results suggest an important role of iNOS in mediating both regressive changes and progressive change in atheromatous plaques.

Endothelium-dependent relaxation of rabbit atherosclerotic aorta was not restored by control of hyperlipidemia: the possible role of peroxynitrite (ONOO(-)).

We determined the role of ONOO(-) in nitric oxide (NO) mediated vascular response in atherosclerosis and regression following removal of dietary cholesterol. The effect of ONOO(-) on NO-mediated vascular responses was examined in vitro. Basal and stimulated NO release was estimated by an NO-selective electrode as well as vascular response and the plasma NO metabolites. An immunohistochemical study was also carried out. Responses were compared in normal controls, atherosclerotic rabbits fed 1% cholesterol diet for 6 or 9 weeks (atherosclerotic group) and animals fed a normal diet for 6-36 weeks after the high cholesterol diet for 6 or 9 weeks (regression group). ONOO(-) impaired the basal and acetylcholine-stimulated NO release, but did not affect endothelium-independent relaxation. After 15 weeks on a normal diet, the acetylcholine-stimulated and basal NO-mediated relaxation, which was diminished in the aorta induced by 6 weeks high cholesterol diet, became restored. However, the vascular response in the 9 weeks high cholesterol diet group did not return to normal after 36 weeks on a normal diet. iNOS was observed in atherosclerotic plaques in atherosclerotic and regression groups along with ONOO(-) in the 9 weeks high cholesterol diet group, but not in the 6 weeks group. Conclusively, ONOO(-) can play a role in impairment of NO-mediated vascular response during the regression of dietary cholesterol-induced atherosclerosis, not in the initiation of atherosclerosis.

A HMG-CoA reductase inhibitor improved regression of atherosclerosis in the rabbit aorta without affecting serum lipid levels: possible relevance of up-regulation of endothelial NO synthase mRNA.

We determined the role of Fluvastatin: HMG-CoA reductase inhibitor on the regression of atherosclerosis following removal of dietary cholesterol. Male rabbits fed a 0.5% cholesterol diet for 12 weeks were divided into three groups: A1, hypercholesterolemic; A2, fed a regular diet for an 12 additional weeks; and A3, fed a regular diet with fluvastatin (2 mg/kg/day). Fluvastatin treatment (A3) did not affect serum lipid levels compared with A2. However, it decreased the atherosclerotic area in the aortic arch and decreased total and esterified cholesterol concentrations in the descending aorta. Tone-related basal NO release in the thoracic aorta was larger in A3 than in A2. eNOS mRNA in vessel was determined by competitive RT-PCR assay. It increased in A1, compared with normal aorta and decreased in A2; however, it did not decrease in A3. This is the first report of a decrease in eNOS mRNA in atherosclerosis after removal of dietary cholesterol and a reversal of it by a HMG-CoA reductase inhibitor, which may contribute to the regression of atherosclerosis.

Import into mitochondria of phospholipid hydroperoxide glutathione peroxidase requires a leader sequence.

An in vitro import system was used to characterize the mechanism of import of phospholipid hydroperoxide glutathione peroxidase (PHGPx) into mitochondria. Mitochondria were isolated from rat liver and incubated at 25 degrees C with [35S]methionine-labeled products of the in vitro translation of mRNA that encoded 23-kDa and 20-kDa PHGPx. 23-kDa PHGPx was imported into mitochondria in a time-dependent manner and was processed to yield the 20-kDa form of PHGPx. The 20-kDa form of PHGPx, without a leader sequence, associated weakly with mitochondria but was not imported. An analysis with an uncoupler of oxidative phosphorylation showed that a membrane potential in the mitochondria was also required for the import of PHGPx. It appears, therefore, that the leader sequence in the precursor to PHGPx is the signal for import into the mitochondria. This is the first report to indicate that the precursor to PHGPx is imported into the mitochondria via the action of a leader sequence.

Overexpression of phospholipid hydroperoxide glutathione peroxidase suppressed cell death due to oxidative damage in rat basophile leukemia cells (RBL-2H3).

The role of phospholipid hydroperoxide glutathione peroxidase (PHGPx) in the cellular defense against oxidative stress was investigated in a novel cell model. We isolated stable transfectants of RBL-2H3 cells that overexpressed PHGPx. The activity of PHGPx in RBL2H3 cells that had been transfected with the 761bp cDNA for rat PHGPx (RPHGPx2) that we had cloned previously was 3.8 times higher than that in parent cells and in cells that had been mock-transfected with the vector without a cDNA insert. Cells that overexpressed PHGPx were three times more resistant than parent cells and mock-transfected cells to the cytotoxic effects of an radical initiator (AAPH) that induced the oxidative stress. This resistance to damage by AAPH of cells that overexpressed PHGPx was not observed after pretreatment with buthionine sulfoximine (BSO), an inhibitor of the synthesis of glutathione. Overexpression of PHGPx could suppress the peroxidation of membrane lipids and, in particular, the production of phosphatidylcholine hydroperoxide by AAPH in RBL2H3 cells. PHGPx was also able to prevent cell death in response to extracellular attack by a lipid peroxide. This is the first report to indicate directly that PHGPx can scavenge phosphatidylcholine hydroperoxide, which induces oxidative damage at the cellular level.

Molecular cloning and functional expression of a cDNA for rat phospholipid hydroperoxide glutathione peroxidase: 3'-untranslated region of the gene is necessary for functional expression.

A full-length cDNA clone for phospholipid hydroperoxide glutathione peroxidase (PHGPx) was isolated from a rat brain. The cDNA was 0.761 kb in length and encoded 170 amino acids, which included a TGA-encoded selenocysteine at residue 46. The protein has a calculated molecular mass of 19,473 Da. We succeeded in the transient functional expression of a full-length cDNA for PHGPx, which includes the 3'-UTR, in COS-7 cells at the first attempt. Deletion of the 3'-UTR prevented the expression of the PHGPx activity and the incorporation of [75Se]selenious acid into the monomeric 19.7 kDa PHGPx protein. Thus, the 3'-UTR of the cDNA for PHGPx was required for the functional expression of PHGPx. Northern blot analysis demonstrated that the mRNA for PHGPx was widely expressed in normal rat tissues, especially in the testis. The mRNA levels of PHGPx in the cultured cells such as hepatomas, neuronal cells, nephroblastoma, and mammary myo-epithelial cells were higher than those of the tissues. The ratio of PHGPx to cytosolic glutathione peroxidase (cGPx) was significantly high in the testis and relatively high in the cultured cells. The mRNA levels of PHGPx in tissues were lower than those of cGPx.