Characteristics of a granular electronic system in Heusler-type Fe2+xV1-xAl.

We report comprehensive measurements of the magnetic, transport, and thermal properties of the Heusler-type compound Fe2+xV1-xAl, with x values near the ferromagnetic quantum critical point, xc âˆ¼ 0.05. At T âˆ¼ 60 K, a prominent Schottky-like anomaly appeared in the specific heat; this anomaly was correlated with a smaller pseudo-gap formation in magnetic susceptibility, magnetoresistance, and thermoelectric power. Furthermore, a magnetic anomaly observed in the magnetic susceptibility and resistivity at T âˆ¼ 4 K was suppressed significantly by applying a magnetic field. A magnetically inhomogeneous phase arose below T âˆ¼ 60 K, which appeared to consist of ferromagnetic and paramagnetic clusters.

Excitation Energy-Transfer Dynamics of Brown Algal Photosynthetic Antennas.

Fucoxanthin-chlorophyll-a/c protein (FCP) complexes from brown algae Cladosiphon okamuranus TOKIDA (Okinawa Mozuku in Japanese) contain the only species of carbonyl carotenoid, fucoxanthin, which exhibits spectral characteristics attributed to an intramolecular charge-transfer (ICT) property that arises in polar environments due to the presence of the carbonyl group in its polyene backbone. Here, we investigated the role of the ICT property of fucoxanthin in ultrafast energy transfer to chlorophyll-a/c in brown algal photosynthesis using femtosecond pump-probe spectroscopic measurements. The observed excited-state dynamics show that the ICT character of fucoxanthin in FCP extends its absorption band to longer wavelengths and enhances its electronic interaction with chlorophyll-a molecules, leading to efficient energy transfer from fucoxanthin to chlorophyll-a.

Saliva-promoted adhesion of Streptococcus mutans MT8148 associates with dental plaque and caries experience.

Colonization of enamel surfaces by Streptococcus mutans is thought to be initiated by the attachment of bacteria to a saliva-derived conditioning film (acquired pellicle). However, the clinical relevance of the contribution of saliva-promoted S. mutans adhesion in biofilm formation has not yet been fully elucidated. The aim of this study was to correlate saliva-promoted S. mutans adhesion with biofilm formation in humans. We correlated all measurements of salivary factors and dental plaque formation in 70 healthy subjects. Dental plaque development after thorough professional teeth cleaning correlated positively with S. mutans adhesion onto saliva-coated hydroxyapatite pellets and the glycoprotein content of either parotid or whole saliva. Saliva-promoted S. mutans adhesion and glycoprotein content were also positively correlated with each other in parotid and whole saliva. By contrast, neither salivary mutans streptococci, Lactobacillus nor Candida correlated with biofilm formation. Parotid saliva-mediated S. mutans adhesion was significantly higher in 12 caries-experienced (CE) subjects than in 9 caries-inexperienced (CI) subjects. Salivary S. mutans adhesion was significantly less (p < 0.01) in the CI group than in the CE group. In conclusion, the present findings suggest the initial S. mutans adhesion, modulated by salivary protein adsorption onto the enamel surface, as a possible correlate of susceptibility to dental plaque and caries.

Statherin and histatin 1 reduce parotid saliva-promoted Streptococcus mutans strain MT8148 adhesion to hydroxyapatite surfaces.

Small salivary phosphoproteins--statherin (ST) and histatin 1 (HT1) - are found in the acquired enamel pellicle which modulates Streptococcus mutans adhesion onto dental enamel. However, their roles in S. mutans adhesion onto enamel surfaces are still undefined. The aim of this study was to investigate whether and how ST and HT1 affect (i) S. mutans adhesion and (ii) the adsorption of S. mutans adhesion-promoting salivary proteins onto hydroxyapatite (HA) in vitro. We fractionated human parotid saliva by adsorption to HA and further by gel filtration chromatography. Adhesion of [3H]-labeled S. mutans strain MT8148 onto sintered HA plates was promoted significantly (>10-fold) by high-molecular weight glycoprotein fraction (HMWGP), but not by purified ST or HT1. More interestingly, promotion of S. mutans adhesion onto HA by HMWGP was significantly reduced by adding purified ST or HT1 to HMWGP. [3H]-labeled S. mutans adhesion on HA was positively correlated to the [14C]-labeled HMWGP adsorption onto HA, which was also reduced by the addition of purified ST and HT1. Synthetic peptides corresponding to ST and HT1 reduced the parotid saliva-promoted S. mutans adhesion. However, removal of the negative charges in the N-terminal domains of ST and HT1 diminished their inhibitory effects on S. mutans adhesion promoted by parotid saliva. We conclude that ST and HT1 competitively inhibit the adsorption of salivary HMWGP, and thereby reduce S. mutans adhesion onto HA surfaces.

Reduction of saliva-promoted adhesion of Streptococcus mutans MT8148 and dental biofilm development by tragacanth gum and yeast-derived phosphomannan.

The aim of this study was to investigate materials which reduce saliva-promoted adhesion of Streptococcus mutans onto enamel surfaces, and their potential in preventing dental biofilm development. The effects of hydroxyapatite (HA) surface pretreatment with hydrophilic polysaccharides on saliva-promoted S. mutans adhesion in vitro and de novo dental biofilm deposition in vivo were examined. Saliva-promoted adhesion of S. mutans MT8148 was significantly reduced by pretreatment of the HA surface with tragacanth gum (TG) and yeast-derived phosphoglycans. Extracellular phosphomannan (PM) from Pichia capsulata NRRL Y-1842 and TG reduced biofilm development on lower incisors in plaque-susceptible rats when administered via drinking water at concentrations of 0.5% and 0.01%, respectively. The inhibitory effect of TG on de novo dental biofilm formation was also demonstrated when administered via mouthwash in humans. It is concluded that TG and yeast-derived PM have the potential for use as anti-adherent agents and are effective in reducing de novo dental biofilm formation.

Oral health care status of homebound elderly in Japan.

We examined the present conditions of oral health care in order to contribute towards an effective system to provide oral health care for homebound elderly in Japan. A questionnaire was mailed to homebound elderly subjects (n=908) and returned by mail. A 73.6% response was achieved. The questionnaire was designed to elicit information with respect to the general condition of the subjects and independence of oral health care. About 70% of the subjects were chair- or bed-bound. Among all subjects, 37.6% required partial or full assistance on toothbrushing, 55.6% on cleaning dentures and 46.7% on eating. The degree of oral health care tended to be poor for chair- or bed-bound elderly compared with independent or house-bound elderly. Homebound elderly with lower Activities of Daily Living Scale (ADL) required more support for oral health care compared with elderly with higher ADL.

Comparison of the activity of four chitosan derivatives in reducing initial adherence of oral bacteria onto tooth surfaces.

We examined the effects of four kinds of chitosan derivatives on initial adherence of oral bacteria onto human anterior teeth surfaces. The buccal surfaces of anterior teeth were used as the experimental surfaces. They were divided into five rectangle areas with outer dimensions of about 2 mm x 4 mm. After applying two ml of a sample solution onto the tooth surfaces, an examiner wiped each rectangle area with a sterilized plastic swab one, three and six hours later. Then we measured bacterial counts in sterilized swabs with mitis salivarius agar. We found that the order of magnitude of the inhibitory effect on the adherence of oral bacteria was low molecular chitosan > phosphorylated chitosan > amorphous chitosan > carboxymethyl chitosan. The solution containing 0.5% low molecular chitosan depressed the bacterial adherence to the same extent as a 50 ppm chlorhexidine digluconate solution for three hours, and 0.1% phosphorylated chitosan also exhibited an inhibitory effect in bacterial adherence for one hour. Amorphous chitosan had a moderate inhibitory effect, but no clear inhibitory activity was found with 0.1% carboxymethyl chitosan. These results suggest that low molecular chitosan and phosphorylated chitosan have the potential to effectively inhibit the initial adherence of oral bacteria onto human tooth surfaces.

Effect of rinsing with phosphorylated chitosan on four-day plaque regrowth.

This clinical investigation examined the effect of phosphorylated chitosan rinsing on plaque development and on the buffering capacity of plaque suspension. Three male adult subjects participated in the trial that was designed as a single blind study. Participants refrained from mechanical oral hygiene procedures during a four-day study and rinsed three times a day with 20 ml of test solutions. A wash-out period of three days was instituted between the placebo and phosphorylated chitosan rinsing period. Clinical evaluation and plaque sampling were performed at the end of each test period. We disclosed plaque accumulations on the buccal upper front teeth with a two-tone disclosing agent to distinguish between newly formed plaque and old plaque. After taking color slides, we then used a computerized image analysis. Tooth areas covered by plaque on the color slides were digitized and expressed as percentages of the tooth area. The buffering capacity of the collected plaque fluid was determined by using a beta-titrator. A mouth rinse containing 0.5% phosphorylated chitosan significantly reduced both newly formed plaque areas (red disclosed; p < 0.001) and old plaque areas (blue disclosed; p < 0.01) compared to a placebo rinsing. However there was no significant difference in the plaque buffering capacity (p > 0.05) between the mouth rinse containing 0.5% phosphorylated chitosan and placebo. These findings might suggest that mouth rinse containing phosphorylated chitosan would be effective in reducing plaque formation and have a slight ability to enhance plaque buffering capacity.

Effect of Er:YAG laser irradiation on acid resistance to bovine dentin in vitro.

Resin bond strength to Er:YAG laser irradiated dentin has been reported to be lower than that of unlased dentin. The reasons have been much discussed, but not clarified. One hypothetical cause has been discussed that lased dentin is acid resistant, therefore, the etching effect of acid conditions decreases. The purpose of this study was to evaluate the acid resistance of laser-irradiated dentin and compare it with the dissolved mineral of Er:YAG laser irradiated dentin and unlased dentin. This experiment was a pilot study to assess the etching effect of pre-conditioner for resin bonding to lased dentin. Bovine dentin was irradiated by Er:YAG laser and immersed in 0.1 M lactic buffer solution (pH 4.0). The dissolved Ca and P in the solution were then both measured. Dissolved Ca from lased dentin was not significantly different from that coming from unlased dentin (p > 0.05). The molar ratio of Ca/P did not differ significantly between lased and unlased dentin, either (p > 0.05). Under FE-SEM view before immersion, the dentin surface was covered with a smear layer in unlased dentin, but this layer was not clearly observed in lased dentin. These results suggested that the lased dentin had little or no resistance to lactic buffer solution.

Association between plasma homocysteine concentration and carotid atherosclerosis in hemodialysis patients.

Accelerated atherosclerosis is a major risk for uremic patients undergoing long-term hemodialysis. Because hyperhomocysteinemia may influence this condition, 168 such patients were examined for a possible association between plasma total homocysteine concentration (tHcy) and conventional cardiovascular risk factors. Generalized atherosclerosis was indicated by excessive intimal-medial wall thickness (IMT) of the extracranial carotid artery as measured by B-mode ultrasonography. The results documented tHcy in these patients of 33.0+/-16.9 micromol/L, a significantly higher amount than that of healthy subjects (11.0+/-3.1 micromol/L, p<0.0001). The patients' carotid maximum IMT was 1.79+/-1.16 mm. In multiple regression analyses with forward elimination procedure, carotid maximum IMT was clearly related to age (r = 0.417, p<0.0001), systolic blood pressure (r = 0.262, p = 0.0043), smoking (r = 0.177, p = 0.0076), duration of hemodialysis (r = 0.083, p = 0.0045), and tHcy (r = 0.195, p = 0.0021). These 5 factors accounted for 36.0% of the variation in carotid maximum IMT. Factors determined as unrelated were male gender, diastolic blood pressure, body mass index, total and HDL cholesterol, triglyceride, lipoprotein(a), uric acid, calcium, inorganic phosphate, and parathyroid hormone. Therefore hyperhomocysteinemia, along with advanced age, systolic hypertension and smoking aggravates atherosclerosis in chronic uremic patients.

Improvement of myocardial fatty acid metabolism through L-carnitine administration to chronic hemodialysis patients.

The concentration of carnitine, which is essential to fatty acid metabolism, can decrease markedly in patients on long-term hemodialysis coincident with life-threatening cardiac damage. However, administration of L-carnitine improves the myocardial function of these patients. To evaluate the underlying events of this phenomenon, we used recently developed technology, (123)I-labeled beta-methyl-p-iodophenyl-pentadecanoic acid (BMIPP) myocardial scintigraphy, as a test of myocardial fatty acid metabolism. Our results showed that the free carnitine concentration (19.2 +/- 6.5 micromol/l) was lower in 11 chronically dialyzed patients than in 8 healthy controls (49.3 +/- 7.7 micromol/l, p < 0. 0001). Additionally the heart to mediastinal ratio (H/M) of BMIPP was higher for these patients than for the controls (1.91 +/- 0.19 vs. 1.52 +/- 0.24, p < 0.005), and the patients' washout rate (WOR) of BMIPP was lower (17.2 +/- 6.0 vs. 22.8 +/- 4.2%, p < 0.05). After L-carnitine was administered orally to the patients at doses of 1 g/day for 1 month and 0.5 g/day for the following month, the concentration of free carnitine in their sera increased to 85.4 +/- 27.0 micromol/l (p < 0.0001). Although the H/M ratio did not change (1.89 +/- 0.20) with this treatment, their WOR increased to 21.9 +/- 6.6% (p < 0.001), similar to that of controls. The left ventricular end-diastolic dimension and left ventricular fractional shortening remained unchanged, as shown by echocardiography. The results presented here denote that a carnitine deficiency in chronically hemodialyzed patients disrupts their myocardial fatty acid metabolism, which is improved by L-carnitine supplementation.

Gender differences in oral health behavior and general health habits in an adult population.

This study aimed to evaluate gender differences in oral health behavior and general health habits in adults. The subjects were 207 males and 196 females aged 20-64 yrs who were public officials in the city or town administrations in Chiba Prefecture, Japan. The questionnaire survey included three items: (1) self assessment of oral health status, (2) oral health behavior and (3) general health habits. Statistical analysis was performed using the chi-square test for differences of responses between males and females. The proportion of subjects with cognition of symptoms of oral disease ranged from 14.3 to 23.0%. The percentage of those who had not visited a dentist in the last year were 52.7% for males and 36.7% for females (p < 0.01). Subjects who brushed their teeth almost every day at bed time were 60.9% of males and 88.8% of females (p < 0.01). A comparison of the numbers of positive responses regarding general health habits found no differences in the distribution of general health habits score between males and females. Examining the relationship between oral health behavior and general health habits revealed that males with general habit high scores tended to have positive oral hygiene behavior. These results support the thesis that gender specificities in oral health depend on individual attitudes to oral health and dental utilization. In addition, understanding the cognitive factors of males and females would accelerate dental approaches to modifying oral health behavior of both groups, thus contributing to lifelong health maintenance.

Caries-inducing activity of the hydrogenated derivative of an isomaltooligosaccharide mixture in rats.

The caries-inducing activity of the hydrogenated derivative of an isomaltooligosaccharide mixture (IMO-H) was evaluated in vitro for its acidogenicity and in vivo an experimental caries system with specific-pathogen-free (SPF) rats. Streptococcus sobrinus 6715 (serotype g) did not produce a significant amount of acid from IMO-H, whereas Streptococcus mutans MT8148 (serotype c) gradually produced a small amount of acid, although the degree was less than that of sucrose. In vivo experiments were conducted on rats which were provided with the test sugars at two different times: at the time of organism inoculation, and after the organisms had become completely established. IMO-H did not induce significant dental caries in rats infected with the S. sobrinus 6715 or S. mutans MT8148R strain.

Self-reported oral hygiene habits, health knowledge, and sources of oral health information in a group of Japanese junior high school students.

The purpose of the present study was to analyze self-reported oral hygiene habits, sources of oral health information, and oral health knowledge in a group of Japanese junior high school students and to determine whether there is a need for improvement in the school's present oral health instruction. A sample of 110 students aged 12-14 in Chiba City were surveyed by means of a questionnaire composed of 24 multiple choice questions. The questions focused on: (1) experience of school-based oral health education, (2) sources of oral health information, (3) knowledge about dental caries, periodontal disease, and the preventive action of fluoride, (4) oral hygiene habits, and (5) dietary behavior. Results showed that more than two-thirds of the students had participated in some kind of school-based oral health education program. Most students (76%) claimed that toothbrushing was the main event attended and 63% claimed that toothbrushing was the main subject they had been taught. The school nurse was identified by 48% of the students as their main source of oral health information in school-based oral health education. When asked to identify their main source of oral health information, most of the students identified "school". Half of the students (48%) identified dental plaque as the main cause of dental caries but only 31%, as the main cause of periodontal disease. Few students (11%) were able to identify the preventive action of fluoride; 58% answered "I don't know"). These results suggest that a meaningful target for the oral health education of children should be the improvement of the school's oral health instruction.

Effects of a hydrogenated isomaltooligosaccharide mixture on glucan synthesis and on caries development in rats.

The caries inhibitory effect of the hydrogenated derivative of an isomaltooligosaccharides mixture (IMO-H) was examined in vitro and in vivo experiments. IMO-H could not be used as a substrate for the crude glucosyltransferases (GTases) of Streptococcus sobrinus 6715 to synthesize water-insoluble glucan. Moreover, it not only significantly inhibited the synthesis of water-insoluble glucan from sucrose, but also the sucrose-dependent adherence of these growing cells the glass surfaces. In the in vivo experiment, the addition of IMO-H to a sucrose-containing diet resulted in significant reduction of caries development in specific-pathogen-free (SPF) rats infected with S. sobrinus 6715.

Effects on acute organophosphorus poisoning in rats in aging and solubility of organophosphates.

Various organophosphorus compounds with low acute toxicity are predominantly used as insecticides worldwide. Human acute organophosphorous poisoning often occurs as a result of accidental, criminal or suicidal ingestion. We determined the effect of rat age and lipid solubility of organophosphates on acute organophosphorus poisoning.After trichlorfon with high water solubility was administered to rats, it and its metabolite, dichlorvos, rapidly disappeared from blood, liver, kidneys and fat-tissues, and the ChE activity in the serum, erythrocytes and brain was rapidly normalized. Dichlofenthion disappeared very slowly from poisoned rats due to its fat-solubility. ChE activity was inhibited for a long time by dichlofenthion released from adipose reservoirs in the whole body, especially in 40-week-old rats, and normal and obese rats at 80 weeks of age. Three-week-old rats, which were at a sexually immature developmental stage, showed mild symptoms of dichlofenthion poisoning. By contrast, 7-week-old rats were poisoned most severely with dichlofenthion and their ChE activity was the most severely inhibited among 3-, 7-, 40-and 80-week-old rats. The recovery of ChE activity in rats poisoned with fenitrothion was the most protracted because of the rapid aging of ChE phosphorylated by fenitrothion, although fenitrothion disappeared more rapidly from rat tissues than dichlofenthion.These findings in rats demonstrated that the pattern of recovery and the degree of symptoms of acute organophosphorus poisoning differed with age and the organophosphate.

A modified device for long term sampling of parotid saliva in various experimental conditions.

A parotid cup has been widely used as an intraoral device for the collection of parotid saliva. However, in long duration sampling, the cup tends to disconnect under circumstances such as mastication, sleep or physical exercise. We have designed a modified device of parotid cup for saliva collection to overcome these unfavorable conditions. The parotid cup was modified by fixing it to the bite-plate appliance which was adjusted individually to the occlusal plane in order to avoid disconnection of the cup under varying conditions. Using this device, we could measure salivary flow rate during mastication, sleep or physical exercise. Additional advantages of this device are that it is easy to make with acrylic resin and is inexpensive. The preliminary study using this device showed that flow rates of unstimulated parotid saliva varied from 0.06 +/- 0.04 ml/min. to 0.16 +/- 0.10 ml/min. (mean +/- s.d) from 7 a.m. to 12 p.m. in 7 subjects. In five subjects, the flow rate of parotid saliva during meal (lunch) was much higher than that of resting on a chair, playing table tennis, or sleeping at night for 6-8 hours. This might be considered due to the stimuli of the meal content. Flow rates of saliva were also examined with various stimuli. The results showed that salty pickled plum > sour lemon juice > 10% ascorbic acid > sweet milky candy > 1% ascorbic acid. These data suggest that our modified device is useful for various experiments in salivary research.

Evaluation of acidogenicity of commercial isomaltooligosaccharides mixture and its hydrogenated derivative by measurement of pH response under human dental plaque.

The acidogenicity of commercially available isomaltooligosaccharides mixture (IMO) and its hydrogenated derivative (IMO-H) were evaluated by the in vivo pH response under dental plaque of six subjects (aged 25-28) using intraoral apparatus. The apparatus, an indwelling pH sensor of a hydrogen ion-sensitive field effect transducer (ISFET), was placed on the buccal site of the mandibular first molar, and the plaque was accumulated for four days. The test sugars were applied with three methods-dropping the solution directly on the plaque, rinsing the oral cavity with the solution, and sucking a candy made of the test sugar (weight 3-4 g). IMO could not be evaluated as a type of sugar with low acidogenicity, especially by the candy method, but IMO-H could be evaluated as a type of sugar with very low acidogenicity in a similar manner as maltitol or sorbitol in all type of applications. The acidogenic response of dental plaque should be assumed to be closely related to salivary parameters such as the secretion rate or to mutans streptococci level of subjects and types of application.

Estimation of fluoride intake in relation to F, Ca, Mg and P contents in infant foods.

The purposes of this present study were to determine F, Ca, Mg and P contents of infant foods available in Thailand and Japan in relationship to ionization of F from dietary sources and also to estimate the daily F intake of infants during the first six months of life. Samples of 31 and 24 foods from Thailand and Japan were analysed. Microdiffusion technique was used to separate F from food samples. The combination of an F electrode with an ion analyzer was used to determine F. Determination of Ca and Mg of ashed samples were carried out by the atomic absorption spectrophotometry and Chen, Toribara and Warner method was used in P analysis. F content found in infant formulas and supplemented foods were generally low, especially in infant foods in Thailand, while Ca, Mg and P contents were high in various food items tested. The estimation of daily F intake showed that foods cannot provide an infant with a daily F intake at the optimal level. The results of this study indicate that some food constituents play significant roles in daily F intake by influencing F absorption.