Arachidonic acid intake and asthma risk in children and adults: a systematic review of observational studies.

The effect of arachidonic acid (ARA) intake on asthma risk is unclear. The objective of the present review was to systematically evaluate available observational studies on the relationship between ARA exposure and asthma risk in children and adults. A PubMed search was conducted on 22 October 2013 and seventy-three publications were checked against predefined criteria for eligibility. To identify additional eligible publications, potentially relevant articles were searched from bibliographies of articles on ARA and asthma. A total of 2924 citations were scrutinised. Finally, fourteen articles were included. A quality assessment was conducted based on the reporting and methodological quality. A meta-analysis was not conducted; therefore, a qualitative assessment is presented. Three high-, two medium- and ten low-quality studies were reviewed. Eleven studies, including two high- and two medium-quality studies, did not find a significant association between ARA exposure and asthma risk. In contrast, one high-quality study indicated a significant trend toward reducing asthma risk in children with decreasing maternal ARA intake (P trend = 0·025), and one low-quality study reported a significant trend of increasing asthma risk with higher blood ARA levels (P trend = 0·007). In two low-quality studies, asthma patients had significantly lower blood ARA levels than controls (both P < 0·05). These studies did not sufficiently demonstrate any relationships between ARA exposure and asthma risk because of the limited number of studies and their methodological limitations. They seem to suggest that ARA exposure is not consistently associated with asthma risk. Nevertheless, further evidence is required to prove or disprove the association.

Arachidonic Acid and Cerebral Ischemia Risk: A Systematic Review of Observational Studies.

BACKGROUND: Arachidonic acid (ARA) is a precursor of various lipid mediators. ARA metabolites such as thromboxane A2 cause platelet aggregation and vasoconstriction, thus may lead to atherosclerotic disease. It is unclear whether dietary ARA influences the ARA-derived lipid mediator balance and the risk for atherosclerotic diseases, such as cerebral ischemia. Considering the function of ARA in atherosclerosis, it is reasonable to focus on the atherothrombotic type of cerebral ischemia risk. However, no systematic reviews or meta-analyses have been conducted to evaluate the effect of habitual ARA exposure on cerebral ischemia risk. We aimed to systematically evaluate observational studies available on the relationship between ARA exposure and the atherothrombotic type of cerebral ischemia risk in free-living populations. SUMMARY: The PubMed database was searched for articles registered up to June 24, 2014. We designed a PubMed search formula as follows: key words for humans AND brain ischemia AND study designs AND ARA exposure. Thirty-three articles were reviewed against predefined criteria. There were 695 bibliographies assessed from the articles that included both ARA and cerebral ischemia descriptions. Finally, we identified 11 eligible articles and categorized them according to their reporting and methodological quality. We used the Strengthening the Reporting of Observational Studies in Epidemiology Statement (STROBE) checklist to score the reporting quality. The methodological quality was qualitatively assessed based on the following aspects: subject selection, ARA exposure assessment, outcome diagnosis, methods for controlling confounders, and statistical analysis. We did not conduct a meta-analysis due to the heterogeneity among the studies. All eligible studies measured blood ARA levels as an indicator of exposure. Our literature search did not identify any articles that evaluated dietary ARA intake and tissue ARA as assessments of exposure. Seven of the 11 eligible articles were considered to be of low quality. No articles reported a dose-dependent positive association between an increased cerebral ischemia risk and ARA exposure. However, most studies did not assess the risk in each subtype of cerebral ischemia, thus various etiological types of cerebral ischemia risk were involved in their results. KEY MESSAGES: We did not find a positive association between ARA exposure and cerebral ischemia risk. Eligible studies reported inconsistent findings: cerebral ischemia risk did not change or significantly decreased. We could not draw any conclusions due to the limited number of eligible high-quality studies. Further evidence from well-designed observational studies is required. Simultaneously, in order to develop effective preventive measures against cerebral ischemia, it is imperative to establish standardized definitions, nomenclatures, classifications, and diagnostic procedures.

Effect of a dietary supplement containing glucosamine hydrochloride, chondroitin sulfate and quercetin glycosides on symptomatic knee osteoarthritis: a randomized, double-blind, placebo-controlled study.

BACKGROUND: Oral glucosamine and chondroitin sulfate, alone and in combination, have been used worldwide for the treatment of osteoarthritis (OA), but their efficacy is controversial. This clinical study was aimed at investigating the potential of a dietary supplement containing glucosamine and chondroitin sulfate in combination with derivatives of quercetin, a naturally occurring flavonoid, (GCQ supplement) for knee OA care. RESULTS: A randomized, double-blind, placebo-controlled study was conducted in 40 Japanese subjects with symptomatic knee OA. Subjects were randomly assigned to GCQ supplement (1200 mg glucosamine hydrochloride, 60 mg chondroitin sulfate and 45 mg quercetin glycosides per day) or placebo and the treatment and follow-up were continued for 16 weeks. The results of symptomatic efficacy assessment based on Japanese Orthopaedic Association criteria showed that scores for two of the four symptom/function subscales, as well as the aggregate scores, were significantly improved at week 16 or earlier in the GCQ group compared to the placebo group. Moreover, analyses of cartilage metabolism biomarkers showed a trend of improvement in type II collagen synthesis/degradation balance in the GCQ group during follow-up. CONCLUSION: GCQ supplement was thought to be more effective than placebo in decreasing the intensity of knee OA-associated clinical symptoms.

Expressions of RANKL/RANK and M-CSF/c-fms in root resorption lacunae in rat molar by heavy orthodontic force.

The differentiation and functions of osteoclasts are regulated by receptor activator of nuclear factor-κB (RANK)/receptor activator of nuclear factor-κB ligand (RANKL) system that stimulates osteoclasts formation. Macrophage colony-stimulating factor (M-CSF) is also essential for osteoclastogenesis. A recent immunocytochemical study reported that RANKL/RANK and M-CSF/c-fms were localized in the periodontal ligament of rat molars during experimental orthodontic tooth movement. The present study focused on the expressions of RANKL/RANK and M-CSF/c-fms in root resorption area during experimental tooth movement in rats. Forty 6-week-old male Wistar rats were subjected to an orthodontic force of 10 or 50 g with a closed coil spring (wire size: 0.005 inch, diameter: 1/12 inch) ligated to the maxillary first molar cleat by a 0.008 inch stainless steel ligature wire to induce a mesial tipping movement of the upper first molars. Experimental tooth movement was undertaken for 10 days. Each sample was sliced into 6 µm continuous sections in a horizontal direction and prepared for haematoxylin and eosin (H and E) and immunohistochemistry staining for tartrate-resistant acid phosphatase (TRAP), RANK, RANKL M-CSF, and c-fms in root resorption area. Statistical analysis was carried out using a Mann-Whitney U-test with a significance level of P<0.01. On days 7 and 10, immunoreactivity for RANKL/RANK and M-CSF/c-fms was detected in odontoclasts with an orthodontic force of 50 g, but not 10 g. Therefore, RANKL/RANK and M-CSF/c-fms systems may be involved in the process of root resorption by heavy orthodontic force.

In vitro antibacterial and cytotoxicity assessments of an orthodontic bonding agent containing benzalkonium chloride.

OBJECTIVE: To assess the antibacterial activity and cytotoxicity of an orthodontic bonding material containing an antibacterial agent. MATERIALS AND METHODS: Superbond C&B (4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane [4-META/MMA-TBB]) resin was mixed with benzalkonium chloride (BAC) to obtain final BAC concentrations of 0.25%, 0.75%, 1.25%, 1.75%, 2.5%, and 5.0% (wt/ wt). Antibacterial activity against Streptococcus mutans and Streptococcus sobrinus was evaluated by soaking the BAC-resin in distilled water at 37 degrees C for periods of 30, 90, and 180 days. Antibacterial activity of the BAC-resin was measured by the disk diffusion method, and the inhibition zone around each sample was measured and recorded. For evaluation of cytotoxicity, BAC-resin samples were put into cell culture inserts placed above human gingival cells and were incubated at 37 degrees C for 1, 3, and 6 days. Cytotoxicity was assessed with a tetrazolium bromide reduction assay. RESULTS: The antibacterial activity of BAC-incorporated resin samples decreased significantly after immersion in water for 180 days, regardless of BAC concentration. The antibacterial activity of nonimmersed resin containing 0.25% or 1.75% BAC was comparable with that of 5.0% BAC-resin immersed for 180 days. In cytotoxicity tests, most cells died when exposed to resins containing 1.75%, 2.5%, and 5% BAC. No difference was observed between resins containing 0.25% and 0.75% BAC at 1, 3, and 6 days of culture. CONCLUSIONS: The addition of BAC to 4-META/MMA-TBB resin confers an antibacterial effect even after immersion in water, and 4-META/MMA-TBB resin containing 0.25% to 0.75% BAC has no significant cytotoxic effect.

Antibacterial activity and shear bond strength of 4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane resin containing an antibacterial agent.

OBJECTIVE: To produce an antibacterial adhesive for orthodontic bonding without compromising the mechanical property. MATERIALS AND METHODS: We added benzalkonium chloride (BAC) to the Superbond C&B (4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane [4-META/MMA-TBB]), a resin that exhibits a strong bonding strength between enamel and bracket. BAC concentrations in the BAC composites were 0.25%, 0.75%, 1.25%, 1.75%, 2.5%, and 5% (wt/wt). Antibacterial activity of the BAC composite was measured by the disk diffusion method. BAC-composite discs were placed on the surface of the agar inoculated with Streptococcus mutans and Streptococcus sobrinus, and the plates were incubated at 37 degrees C. After 48 hours of incubation, the inhibition zone around each sample was measured and recorded. The BAC-modified composite was used to bond metal brackets to the phosphoric acid-etched enamel surface of human premolars. The shear bond strengths were measured after immersion in water at 37 degrees C for 24 hours. RESULTS: The BAC-composite samples showed significant (P < .0001) antibacterial activity compared with the control. Measurable zones of bacterial inhibition increased as the BAC content in test samples increased. The shear bond strength declined with the increase in BAC concentration in the composite. A significant difference was found between the control composite and composites containing 1.25%, 1.75%, 2.5%, and 5% BAC (P < .05). No significant difference was found between the control composite and composites containing 0.25% and 0.75% BAC. However, shear bond strengths of the modified composites ranged from 10.12 MPa to 20.94 MPa. CONCLUSIONS: These results confirmed that BAC-modified 4-META/MMA-TBB resin has a possibility for clinical application as an orthodontic bonding adhesive.

Effect of thermal cycling on shear bond strength with different types of self-etching primer for bonding orthodontic brackets using a MMA-based resin.

The purpose of this study was to determine the bonding durability when orthodontic bracket was bonded to human enamel using a MMA-based resin (Multibond) with two types of commercially available self-etching primer - Multibond and Megabond. Multibond primer contained a polymerization initiator, but Megabond primer did not. No significant differences in shear bond strength were observed between Multibond and Megabond primers after immersion in water at 37 degrees C for 24 hours (before thermal cycling). Multibond primer produced no significant decrease in shear bond strength after 2000 and 5000 thermo-cycles between 5 degrees C and 55 degrees C. On the contrary, Megabond primer showed significant decrease in shear bond strength after thermal cycling. The present study suggested that if Multibond resin were to be used for bonding orthodontic brackets, difference in self-etching primer's components would influence shear bond strength after thermal cycling.

Bonding durability of using self-etching primer with 4-META/ MMA-TBB resin cement to bond orthodontic brackets.

This study determines the bonding durability when a self-etching primer is used with Superbond C&B (a 4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane resin) to bond orthodontic brackets to enamel. Thermocycling test was used to assess bonding durability. Metal brackets were bonded to the phosphoric acid-etched or Megabond self-etching primer-treated enamel surface of human premolars using Superbond C&B. The shear bond strengths were measured after immersion in water at 37 degrees C for 24 hours or after 2000 or 5000 cycles of thermocycling between 5 degrees C and 55 degrees C. Data were analyzed using 2-way analysis of variance and Fisher's protected least significant difference test for multiple comparisons. There was no significant difference in shear bond strength between phosphoric acid and Megabond self-etching primer treatment before the thermocycling test. After 2000 and 5000 thermal cycles, significant decreases in shear bond strength were observed with phosphoric acid etching. On the contrary, no significant differences in shear bond strength were observed after 2000 and 5000 thermal cycles with Megabond self-etching primer. The adhesive remnant indices were not significantly different between phosphoric acid etching and Megabond self-etching primer treatment either before or after thermal cycles. This study suggested that when used with Superbond C&B in bonding orthodontic brackets, Megabond self-etching primer is superior to phosphoric acid as an enamel preparation agent in providing durable bond strength.

Bonding durability between orthodontic brackets and human enamel treated with megabond self-etching primer using 4-META/MMA-TBB resin cement.

The purpose of this study was to determine the bonding durability when a Megabond self-etching primer is used with 4-META/MMA-TBB resin to bond metal orthodontic brackets to human premolar enamel. Three conditions of enamel were prepared: Megabond self-etching primer without saliva contamination, Megabond self-etching primer with saliva contamination, and repeat Megabond self-etching priming after saliva contamination. Shear bond strengths were measured after immersion in water at 37 degrees C for 24 hours, or after 2000 or 5000 cycles of thermal cycling between 5 degrees C and 55 degrees C. There were no significant differences in shear bond strength among the three groups not only before thermal cycling, but also after thermal cycling. FE-SEM observation revealed the presence of saliva and reduced amount of resin tag formation after saliva contamination. The present study provided the evidence in human teeth that when using 4-META/MMA-TBB resin, Megabond self-etching primer treatment produced tight bonding even when surface was contaminated with saliva.

Efficacy of using self-etching primer with a 4-META/MMA-TBB resin cement in bonding orthodontic brackets to human enamel and effect of saliva contamination on shear bond strength.

The objective of this study was (1) to evaluate the effectiveness of Megabond when used with Superbond C&B, a 4-methacryloloxyethyl trimellitate anhydride (4-META)/methyl methacrylate (MMA)-tri-n-butyl borane (TBB) resin, to bond orthodontic metal brackets to human enamel and (2) to examine the influence of saliva contamination on shear bond strength. Metal brackets were bonded to phosphoric acid-etched or Megabond-treated human premolars using Superbond C&B resin cement. The effects of saliva contamination after acid etching or self-etch priming, and the effect of re-etching or self-etch priming after saliva contamination on shear bond strength were also assessed. The shear bond strengths were measured after immersion in water at 37 degrees C for 24 hours. Data were analyzed using two-way analysis of variance and Fisher's protected least significant difference test for multiple comparisons. There were no significant differences in shear bond strength between phosphoric acid etching and self-etch priming for no contamination, saliva contamination, and repeat treatment (etching or priming) after saliva contamination. With phosphoric acid etching, saliva contamination significantly decreased the shear bond strength. Repeat phosphoric acid etching after saliva contamination did not significantly improve the bond strengths. With self-etching primer treatment, however, saliva contamination did not cause any decrease of bond strength. Phosphoric acid etching produced more enamel fracture than self-etching primer treatment. Field-emission scanning microscopy revealed less dissolution of enamel surface resulted from self-etching primer compared with phosphoric acid. These results suggest that Megabond when used with Superbond C&B resin cement may be a good candidate for bonding orthodontic brackets to human enamel.

Involvement of mast cell chymase in bleomycin-induced pulmonary fibrosis in mice.

The possible role of mast cell chymase in organ fibrosis was examined using a bleomycin-induced pulmonary fibrosis model in mice. Intratracheal injection of bleomycin to mice significantly increased not only hydroxyproline content but also chymase activity in the lung. Administration of a chymase inhibitor SUN C8077 (7-chloro-3-(3-amynophenyl) quinazoline-2, 4-dione methanesulfonate) dose-dependently reversed the bleomycin-induced increase in hydroxyproline content as well as chymase activity in the lung. Human chymase digested latent transforming growth factor-beta1 (TGF-beta1) to form mature TGF-beta1 in vitro, which was inhibited by SUN C8077. Human chymase, on the other hand, failed to stimulate DNA synthesis of human lung fibroblasts CCD-8Lu and LL97A. Taken together, it is suggested that mast cell chymase might participate in the pathogenesis of pulmonary fibrosis, and that the chymase-induced fibrosis might be mediated at least in part by TGF-beta1. Chymase inhibitor may be promising for treatment of pulmonary fibrosis in humans.

Human chymase stimulates Ca2+ signaling in human polymorphonuclear cells.

Human chymase is known to function as a chemoattractant for human leukocytes. To investigate the mechanism of the chymase-induced cell migration, change in intracellular calcium concentration ([Ca(2+)]i) was examined in human polymorphonuclear (PMN) cells using Fluo-3 as a fluorescent Ca(2+) indicator. Treatment of PMN cells with human chymase caused [Ca(2+)]i elevation in a concentration-dependent manner. Depletion of extracellular Ca(2+) from the medium partially attenuated the chymase-induced [Ca(2+)]i increase, showing that both Ca(2+) influx and Ca(2+) release from internal stores might be involved in the [Ca(2+)]i response. Pretreatment of the cells with pertussis toxin completely blocked the chymase-induced [Ca(2+)]i signal, suggesting an involvement of G protein in the chymase-mediated [Ca(2+)]i elevation. The data in the present study raise the possibility that the chymase-induced cell migration is mediated by the [Ca(2+)]i elevation, which might be caused by stimulation of a G-protein-coupled receptor such as protease-activated receptors (PARs).

Mouse mast cell protease-1 cleaves angiotensin I to form angiotensin II.

The ability to convert angiotensin (Ang) I to Ang II was compared between human alpha-chymase and two mouse beta-chymases, mouse mast cell protease (mMCP)-1 and mMCP-4. Human chymase hydrolyzed Ang I to produce Ang II without further degradation. mMCP-1 similarly generated Ang II from Ang I in a time-dependent manner and the formation of the fragment other than Ang II was marginal. In contrast, mMCP-4 hydrolyzed Ang I at two sites, Tyr(4)-Ile(5) and Phe(8)-His(9), with Ang II formation being tentative. Consistently, mMCP-4 but not human chymase hydrolyzed Ang II and mMCP-1 showed little hydrolytic activity against Ang II. These data suggest that not only human chymase but also mMCP-1 might possess a physiological role in Ang II formation. Our findings also imply that the Ang-converting activity of chymase may not be related to the categorization of chymase into alpha- or beta-type based on their primary structure.

Role of mast cell chymase in allergen-induced biphasic skin reaction.

Intradermal injection of human chymase (EC 3.4.21.39) into the mouse ear elicited an edematous skin reaction in a biphasic manner, with a transient reaction peaking at 1 hr, followed by a delayed response persisting for at least 24hr. The kinetics of this reaction was analogous to the biphasic skin reaction induced by ascaris extract in actively sensitized mice. A similarity between the two dermatitis models was also shown by histological analysis, i.e. accumulation of inflammatory cells was observed exclusively in the later phases of the skin reaction. A chymase inhibitor, SUN-C8077 [3-(3-aminophenylsulfonyl)-7-chloroquinazorine 2,4(1H, 3H)-dione], significantly inhibited both the early- and late-phase responses of the skin reaction induced by ascaris extract. These findings suggest that chymase may play an important role in the allergen-induced biphasic skin reaction. A histamine receptor antagonist, homochlorcyclizine, inhibited the early-phase but not the late-phase of the chymase-induced skin reaction. In addition, human chymase showed chemotactic activity to human polymorphonuclear leukocytes in vitro. Mast cell chymase may participate in the two phases of allergic skin inflammation by two distinct mechanisms, i.e. histamine- and leukocyte-dependent mechanisms, respectively.

Chymase inhibitor improves dermatitis in NC/Nga mice.

BACKGROUND: Mast cell chymase is thought to participate in allergic inflammation, but its precise role remains undetermined. Inbred NC/Nga mice develop skin lesions similar to atopic dermatitis (AD) when they grow up in a conventional environment. To elucidate the possible role of chymase in AD, we examined the effect of a chymase inhibitor on skin lesions of NC/Nga mice. METHODS: NC/Nga mice were given the chymase inhibitor SUN-C8257 daily at 150 mg/kg/day with drinking water, and the severity of the dermatitis was evaluated on day 35 of the experiment. The role of chymase in dermatitis was further investigated in vitro and in vivo using recombinant mouse mast cell protease-4 (mMCP-4). RESULTS: Administration of SUN-C8257 significantly reduced the clinical skin and histological score in NC/Nga mice. SUN-C8257 also inhibited the accumulation of inflammatory cells, such as eosinophils and mast cells, in the affected lesions in this model. mMCP-4 stimulated eosinophil migration in vitro, and intradermal injection of the enzyme resulted in a significant accumulation of inflammatory cells, including eosinophils, at the injection site. Thus amelioration of the skin lesions in NC/Nga mice by SUN-C8257 might be, at least in part, due to the suppression of cell infiltration in the lesions. CONCLUSION: Mast cell chymase may contribute to the pathogenesis of AD, and SUN-C8257 will be beneficial to the treatment of the skin disorder.

Chymase participates in chronic dermatitis by inducing eosinophil infiltration.

An epicutaneous application of 2,4-dinitrofluorobenzene (DNFB) to a mouse ear caused a transient skin swelling, and the repetition of the challenge enlarged the contact dermatitis. The repeated challenge with DNFB also induced eosinophil infiltration on the application site. Administration of a chymase inhibitor significantly inhibited the ear swelling as well as eosinophil accumulation. An intradermal injection of human chymase to the mouse ear also elicited transient skin swelling and eosinophil infiltration, both of which were augmented in proportion to the number of injections. Human serum albumin and heat-inactivated chymase failed to induce such skin reactions, suggesting the participation of proteolytic activity of the enzyme. In addition, chymase stimulated eosinophil migration in vitro in a concentration-dependent manner. Taken together, these observations suggest that mast cell chymase may contribute to development of the DNFB-induced dermatitis, probably by promoting eosinophil infiltration. It is therefore possible that chymase plays a role in pathogenesis of chronic dermatitis such as atopic dermatitis.

Mast cell chymase regulates dermal mast cell number in mice.

Chymase inhibitor reduced the increase in the number of dermal mast cells in 2,4-dinitrofluorobenzene-induced dermatitis in a dose-dependent manner. Intradermal injection of human chymase to mouse ear significantly increased histamine content, the marker for mast cell number in the skin. These results suggest that chymase released by mast cells may participate in local mast cell accumulation in a positive feedback fashion. Immunohistochemical analysis revealed that the intradermal injection of chymase reduces expression of stem cell factor (SCF) on surface of the skin keratinocytes. In addition, incubation of human keratinocytes with chymase in vitro resulted in release of SCF into the culture medium. Since soluble SCF is thought to regulate mast cell number, the chymase-induced mast cell accumulation may occur via the ability of chymase to process membrane-bound SCF on the epidermal keratinocytes.