Effect of Tooth-Whitening Procedures on Stained Composite Resins.

In this laboratory study, a composite resin was stained to a visibly discernible level using both coffee and red wine over 14 days (change was considered clinically noticeable and significant when ΔEab*≥2.7). Color change was measured at one, three, seven, and 14 days of staining. Although the nature of color change was different for the two staining solutions, the overall degree of staining (ΔEab*) rendered by either coffee or wine at each time interval was not significantly different ( p≥0.05). Four whitening protocols were applied to stained composites. Treatment included applications of distilled water (control), Crest Pro-Health [HD] toothpaste, Crest Whitestrips, Opalescence PF bleach (15%), and application of a fine pumice polishing (Preppies). HD toothpaste and Whitestrips were applied daily for 21 days, Opalescence was applied daily for 10 days, and polishing was applied once. Each of the whitening products, applied in a manner simulating at-home or in-office treatment, was effective in producing color improvements (lightening) over controls ( p<0.05), but none of the four treatments produced lightening that was significantly different from the other treatments ( p≥0.05). A comparison of final composite color with that measured at baseline showed that Opalescence returned composite color to an acceptable level following exposure to both staining solutions (ΔEab*<2.7), Whitestrips returned color close to baseline for wine-stained composites, and HD paste and polishing permitted residual stain to remain (ΔEab*≥2.7).

Perceptions of low-income mothers about the causes and ways to prevent overweight in children.

BACKGROUND: Childhood overweight and obesity remain major health conditions, affecting nearly one-third of children in the USA. Multiple factors have been identified that contribute to children becoming overweight; however, little is known regarding what low-income mothers perceive to be the causes of and the ways to prevent children from becoming overweight. METHODS: Low-income mothers (n = 286) with children aged 4-8 years participated in semi-structured interviews, during which they were asked for their opinions about the causes of and ways to prevent children from becoming overweight. After themes were identified, interviews were coded for the presence or absence of each theme. RESULTS: The majority of mothers were non-Hispanic White (69.2%) and overweight or obese (77.3%). Additionally, many of the children (41.9%) were overweight or obese. Six causes of children becoming overweight were identified by mothers: types or quantities of food eaten (90.9%); parenting behaviours (44.9%); lack of activity (42.3%); genetics, slow metabolism or medical issues (24.5%); stress or emotion (5.2%); and limited access to resources (3.5%). Five ways to prevent children from becoming overweight identified by mothers included the following: healthy eating (84.9%), more activity (54.8%), limiting screen time (19.9%), limiting sugar-sweetened beverages (12.2%) and drinking more water (6.6%). The majority of mothers (77.1%) reported that they carried out their suggestions to prevent their children from becoming overweight. CONCLUSION: Within this cohort with a high prevalence of maternal and child overweight, most mothers identified many of the evidence-based strategies for childhood obesity prevention. Future intervention development may benefit from focusing on content areas that were less commonly identified by mothers as well as helping mothers translate knowledge to implementation.

Optical microcavities formed by semiconductor microtubes using a bottlelike geometry.

We report on the realization of optical microtube resonators with a bottlelike geometry. The measured eigenenergies and the measured axial field distributions of the modes can be described by a straight and intuitive model using an adiabatic separation of the circulating and the axial propagation. The dispersion of the axial mode energies follows a photonic quasi-Schrödinger equation including a quasipotential which can be determined for the actual geometry of the microtube in a precise and simple way. We show that tailoring the geometry of the microtube bottle resonators enables the realization of a wide variety of mode distributions and dispersion relations.

N-trimethyl chitosan chloride: optimum degree of quaternization for drug absorption enhancement across epithelial cells.

N-trimethyl chitosan chloride (TMC) is a polycation that enhances drug transport across epithelia by opening tight junctions. The degree of quaternization of TMC determines the number of positive charges available on the molecule for interactions with the negatively charged sites on the epithelial membrane and thereby influences its drug absorption-enhancing properties. The effects of six different TMC polymers (degree of quarternization between 12% and 59%) on the transepithelial electrical resistance (TEER) of Caco-2 cell monolayers and on the transport of hydrophilic and macromolecular model compounds across Caco-2 cells were determined. All the TMC polymers were able to decrease the TEER markedly in a slightly acidic environment (pH 6.2). However, only TMC polymers with higher degrees of quaternization (> 22%) were able to reduce the TEER in a neutral environment (pH 7.4). The maximum reduction in TEER (47.34 +/- 6.0% at a concentration of 0.5% w/v and pH 7.4) was reached with TMC with a degree of quaternization of 48%, and this effect did not increase further with higher degrees of quaternization of TMC. In agreement with the TEER results, the transport of model compounds across Caco-2 cell monolayers increased with an increase in the degree of quaternization of TMC. However, the transport reached a maximum for TMC with a degree of quaternization of 48% (25.3% of the initial dose for [14C]mannitol and 15.2% of the initial dose for [14C]PEG 4000), and this effect did not increase further with higher degrees of quaternization of TMC. Therefore, the increase in the effects of TMC on intestinal epithelia did not directly correlate up to the maximum quaternization degree of this polymer, but reached an optimum value already at an intermediate degree of quaternization (ca. 48%).

Respiratory muscle endurance in heart failure--the effect of clinical severity.

UNLABELLED: In chronic heart failure there is no single explanation for reduced effort tolerance. Recently, abnormalities of skeletal muscles, which include respiratory muscles, have been described in cases of chronic heart failure. The aim of this study was to investigate the effect of clinical severity of heart failure, measured by means of the Boston score, on respiratory muscle performance (strength and endurance). METHODS: Using the Boston score, we compared 20 patients with chronic heart failure and low ejection fraction to 20 normal people, measuring maximal inspiratory mouth pressures (MIPs), maximal expiratory mouth pressures (MEPs) and endurance. Endurance was measured by repeated maximal static contractions of MIP and MEP as well as maximal voluntary ventilation (MVV). RESULTS: Inspiratory strength (MIP 75 +/- 34 cmH2O) but not expiratory strength (MEP 116.9 +/- 43.7 cmH2O) were reduced in heart failure patients, compared with controls (MIP 96.2 +/- 29.2, MEP 120.4 +/- 31 cmH2O). Endurance of inspiratory muscles was significantly reduced (P < 0.007) but not of expiratory muscles (P > 0.25). Clinical severity did not correlate with reduced endurance. CONCLUSION: Endurance of the inspiratory muscles was reduced in chronic heart failure unrelated to clinical severity.

Effects of diet-age and streptomycin on virulence of Autographa californica M nucleopolyhedrovirus against the tobacco budworm.

Addition of the antibiotic streptomycin to two artificial diets routinely used in bioassays of neonate lar vae of Heliothis virescens (tobacco budworm) infected with Autographa californica M nucleopolyhedrovirus (AcMNPV) increased lethal times of the virus. After storage of diets for 3 weeks at 4 degrees C, lethal times of infected larvae were significantly slower compared to those for larvae bioassayed using diets stored for 2 weeks or less. The effect of diet-age on rate of mortality was not the result of a change in total protein content or pH of the diet, but was apparently the result of some other alteration in the quality of the diet (e.g. microbial spoilage, palatibility, and/or nutritional value unrelated to total protein). Although we did not determine why lethal times were slower in response to streptomycin concentration or diet-age, we did find that slower lethal times were correlated with slower relative growth rates (RGR) of infected larvae. In addition, RGR of infected larvae decreased as a function of increasing streptomycin concentration, diet-age, and the interaction of the two factors. These results demonstrate that it is difficult to obtain consistent and comparable bioassay results if antibiotic composition and diet-age are not controlled. We suggest a standardized diet or highly standardized procedures for a given diet be developed that permits comparison of bioassays among and within laboratories.

Respiratory muscle fatigue after an ultra-marathon measured as inspiratory task failure.

Controversial literature exists concerning the occurrence of inspiratory muscle fatigue during efforts performed outside a laboratory. The purpose of this study was to assess inspiratory muscle strength and endurance time measured as Tlim, the length of time a subject can endure a task before the onset of fatigue, in ultra-marathon runners by simple non-invasive techniques before and after an ultra-marathon (87 km). Ten runners, (8 males and 2 females), who had normal clinical evaluation and lung function underwent inspiratory muscle assessment by measurement of maximal inspiratory mouth pressures and sustained inspiratory mouth pressures at a given target pressure and a given duty cycle. The measurements were performed prior to the race and 3 days after the race. No significant difference was observed in the inspiratory muscle strength 3 days after the race (p > 0.37), but the inspiratory muscle endurance time as measured by Tlim, was significantly lower (p < 0.002), with an overall decrease of 26.5%. Inspiratory muscle strength was normal 3 days after the race, however the inspiratory muscle endurance time as measured by sustained inspiratory pressure was still impaired 3 days after the race.

Lung and respiratory muscle function in limb girdle muscular dystrophy.

BACKGROUND: Pulmonary involvement is frequently observed in patients with limb girdle muscular dystrophy and occurs early in the disease. The aim of this study was to establish the prevalence of pulmonary dysfunction; the type of dysfunction; and any correlation between patient age, disease duration, or limb weakness and lung or respiratory muscle dysfunction. METHODS: Twenty patients with strictly delineated limb girdle muscular dystrophy and 20 healthy controls were evaluated. Full inspiration chest radiographs were obtained. Standard lung and respiratory muscle function tests were performed and the data were statistically analysed. RESULTS: The mean age of the patients was 40.6 years, the mean disease duration was 18.9 years, and the mean average muscle score (a numerical expression of limb weakness) was 5.73 out of 10. Chest radiography showed unilateral paresis of the diaphragm in three patients. Increased residual volumes, with either increased or decreased total lung capacity, correlated inversely with disease duration. Respiratory muscle weakness was common but mild. Expiratory muscle function was more impaired than inspiratory muscle function and correlated positively with expiratory reserve volume. CONCLUSIONS: Respiratory muscle strength is commonly impaired in limb girdle muscle dystrophy. A dissociation of the limb and mild respiratory muscle involvement is observed; wheelchair restriction does not predict worsening of pulmonary function, and patient age, disease duration, or degree of limb weakness do not predict pulmonary morbidity. The diaphragm is not disproportionately affected by the dystrophic process compared with limb muscles.

An antibody to dihydropyridine calcium entry blockers. A comparison with the calcium channel receptor in skeletal muscle.

Antibodies that recognize dihydropyridine (DHP) calcium entry blockers were elicited from rabbits. A sensitive and specific radioimmunoassay for dihydropyridines was developed and its specificity compared to the DHP binding site in skeletal muscle membranes. The antibody bound [3H]nitrendipine with a higher affinity (KD = 0.155 nM) than did the DHP receptor of skeletal muscle (KD = 1-3 mM); however, in contrast to the DHP receptor, the antibody recognized only those DHP drugs with meta-nitrophenyl substituents at the 4-position on the DHP ring. Both the antibody and receptor exhibited stereospecificity, with each site recognizing the (+)-isomer of nicardipine as the more potent. This antibody should prove useful in our studies of some potentially irreversible DHP molecules.

Regulation of glycine receptor binding in the mouse hypoglossal nucleus in response to axotomy.

Recent studies have shown that muscarinic receptors in brain hypoglossal nuclei exhibit a loss of specific ligand binding in response to axotomy of the hypoglossal nerve. The mouse hypoglossal nucleus contains a high level of receptors for the inhibitory neurotransmitter, glycine; the ligand [3H]strychnine binds to the glycine receptor with high affinity. In the present study [3H]strychnine binding in mouse hypoglossal nuclei was examined at 1 to 150 days after unilateral lesions of the hypoglossal nerve. Brains were sectioned on a cryostat, thaw-mounted onto microscope slides, incubated with [3H]strychnine and processed for light microscopic autoradiography. Receptor density was assessed by counting silver grains in photomicrographs of operated and control nuclei. During the first 25 days after axotomy grain density fell to 50 percent of that of the control nucleus. After this time grain density slowly increased, returning to control levels by 150 days post lesion. These data indicate that glycine receptors on the axotomized cells of the hypoglossal nucleus are lost when connection with the target muscles of the tongue is interrupted, and that the receptors reappear when the hypoglossal nerve regenerates. It is suggested that excitatory and inhibitory neurotransmitter receptor systems may be regulated in a coordinated fashion by the functional state of the motoneuron.