Effect of an experimental desensitizing agent on reduction of bleaching-induced tooth sensitivity: A triple-blind randomized clinical trial

Background

In this randomized study, split-mouth, triple-blind clinical trial, the authors evaluated the efficacy of a desensitizing gel that contained 5% potassium nitrate and 5% glutaraldehyde applied before in-office bleaching with 35% hydrogen peroxide (HP).

Bone histomorphometry in 50 normal tunisian subjects

Summary Quantitative bone histomorphometry was done on undecalcified sections of iliac crest bone specimens obtained at autopsy from 50 normal subjects (24 males and 26 females). The following parameters were measured: cortical thickness (Ct.Th), trabecular bone volume (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), osteoid volume (OV/BV), osteoid surfaces (OS/BS), osteoid thickness (O.Th) and eroded surfaces (ES/BS). There was a significant age-related decrease in BV/TV in both sexes which followed a x³ polynomial regression. A significant decrease of Tb.Th was noted in males after the fifth decade. In males, bone loss was 1.5% per decade, but in females it was 0.36% before menopausal period and 2% after. Other parameters were unrelated to age and sex.     

Effect of Histamine on the Permeability of the Nasal Mucosa in vivo

Objective--Histamine is one of the chemical mediators released during the acute phase of allergic rhinitis and is considered to cause the increase in epithelial permeability observed. We tried to examine the effect of histamine on nasal mucosal permeability in vivo. Material and methods--Histamine at different concentrations was administered to the nostrils of healthy subjects and the nasal transepithelial potential difference (PD) was measured. We also examined nasal mucosal permeability by means of a histochemical technique using horseradish peroxidase (HRP) in guinea pigs. Results--Administration of 10^?1 M histamine significantly reduced the nasal PD in healthy subjects. After administration of 5.4×10^?1 M histamine to the noses of guinea pigs, most of the intercellular spaces showed positive reactions to HRP and this effect was significantly inhibited by pretreatment with mepyramine and the antihistamine bepotastine besilate. Conclusion--These results indicate that histamine plays an important role in the change in mucosal permeability observed in allergic rhinitis in vivo via the histamine H₁ receptor.     

The cocktail party effect

The main advantages of wearing 2 ear level hearing aids are the possibilities of directional hearing and of avoiding the acoustical head shadow. These effects are rather easy to measure. There exists another effect which would seem, at first sight, to be of major importance: The fact that in an environment of hampering sounds one understands better with 2 ears than with only 1: the cocktail party effect (CPE).

As in already described [Kuyper and de Boer, 1969] there are many ways to measure and even to define the CPE. The most natural way (and the best if one investigates hearing aids) is to use loudspeakers. Carhart [1965] describes a method which avoids the effect of head shadow. Unfortunately it was impossible for us to obtain in double prothetized subjects an effect which was greater than the variance.

In order to avoid this variance we improved a method developed by Feldmann in 1963, and in this way succeeded in obtaining significant results for each single subject.

Applying this method on prothetized subjects, forced us to use the telephone coil instead of the microphone of the post-aural hearing-aids.     

Significance of the SISI Test and Its Relation to Recruitment

Auditory brainstem responses (ABR) evoked by clicks allow a threshold evaluation for the high-frequency range (2-4 kHz) but not for middle and low frequencies (0.5-1 kHz). In 19 normally hearing subjects aged between 24 and 40 years, ABRs have been recorded using clicks and 0.5- and 1-kHz tone pips, with durations of 6 and 3 ms, respectively, and rise-decay times of 3 and 1.5 ms. The input signal was filtered by a passband filter of 20-5000 Hz. Parameters of tracings elicited by the different kinds of stimuli are compared. Tone-pip ABR morphology does not show the conventional seven peaks but a single large vertex-positive wave. On the ascending branch high-frequency potentials, probably corresponding to the I, II, III and IV-V click-evoked peaks, were visible in some cases, but they rapidly disappeared as the stimulus intensity was decreased. Their 2.3-3 ms greater mean latency values are presumably related to the rise times of the stimuli employed. In terms of bioelectric generators, this large vertex-positive peak probably corresponds to the Jewett V wave. It probably represents a generalized asynchronous dendritic activity. Thus it is possible to obtain ABRs to middle- and low-frequency stimuli. Mean amplitude values of the slow wave are considerably higher than those of the Jewett V wave, but standard deviations are also larger. The positive wave has been identified in response to 1-kHz tone pips in 100% of cases at 30 dB nHL and in 52% of cases at 20 dB, while for 0.5-kHz tone pips in 73.7% of cases at 30 dB and in 57% at 20 dB. On the whole the threshold is located between 15 and 30 dB nHL.

L'étude des potentiels auditifs du tronc cérébral évoqués par des clics permet une évaluation objective du seuil auditif dans le domaine des hautes fréquences (2-4 kHz), mais pas dans celui des fréquences moyennes et basses (0, 5-1 kHz).

Nous avons étudié, chez 19 sujets normo-entendants aˇgés de 24 à 40 ans, les potentiels auditifs du tronc cérébral évoqués par des clics et des pips tonaux de 0,5 et 1 kHz, la durée des pips tonaux étant respectivement de 6 et 3 ms, avec un temps de montee de 3 et 1,5 ms.

Le signal était filtré avec une bande passante de 20-5000 Hz. Nous avons ainsi comparé les paramètres des tracés obtenus avec ces différents types de stimulus et trouvé que les pips tonaux n'évoquaient pas l'apparition des sept pics conventionnels, mais seulement une onde assez ample, positive au vertex; parfois, il est possible de reconnaiˇtre sur sa branche ascendante la présence de potentiels à haute fréquence qui correspondent selon toute probabilité aux pics I, II, III et IV-V évoqués par des clics. Leur amplitude décroiˇt et ils disparaissent lorsqu'on diminue l'intensité de la stimulation. Les latences de cette onde ample, positive au vertex, supérieures de 2,3-3 ms à celles de l'onde V de Jewett, sont probablement liées au temps de montée du stimulus employé. En termes d'origine bioélectrique, cette onde correspond vraisemblablement à celle du pic V de Jewett. Elle semble représenter une activité dendritique, asynchrone. On peut done obtenir des potentiels auditifs du tronc cérébral avec des stimuli de basse et de moyenne fréquence. Les amplitudes moyennes de cette onde sont beaucoup plus importantes que celles du pic V de Jewett, mais les déviations standard sont aussi plus grandes. Cette onde est présente dans 100% des cas pour les pips tonaux de 1 kHz à 30 dB nHL et dans 52% à 20 dB, tandis qu'elle est présente dans 73,7% des cas à 30 dB et dans 57% à 20 dB lorsque on emploie des pips tonaux de 0,5 kHz. Les seuil objectif se situe ainsi entre 15 et 30 dB nHL.     

国内外社区护理研究进展

介绍了社区护理概念及特征,归纳了国内外社区护理沿革及社区护理模式,对国内外社区护理现状进行了研究,重点分析了我国社区护理现状,探索我国与国外社区护理在组织形式与服务内容、人力资源配置、管理方面的差异。     

“针上灸”法与“温针灸”法临床治疗效应的差异比较

目的：通过“针上灸”法与“温针灸”法治疗寒凝血瘀型原发性痛经,来比较“针上灸”法与“温针灸”法临床治疗效应的差异。方法：将患者随机分为“针上灸”组和“温针灸”组,采取相应的治疗,并进行观察。结果：“针上灸”组与“温针灸”组总有效率分别为94．44％、82．86％,通过X^2检验分析,2组总有效率之间没有显著的差异（P〉0．05）;比较2组治疗前后的疼痛积分数据,“针上灸”法的近期疗效要优于“温针灸”法,随访结果显示2种方法的远期疗效都有待提高。结论：“针上灸”法与“温针灸”法临床疗效确切,但前者温热效应更快速,可控性更好;可以充分发挥艾灸时艾油的作用;能最大限度避免出现患者被烫伤和烧坏床单的事故,使患者能以放松的体态和心态接受治疗,达到“两神合一”的最佳治疗效果。     

Prospective assessment of reproducibility of three-dimensional ultrasound for fetal biometry

PurposeTo compare fetal ultrasound measurements performed by two observers with different levels of experience and evaluate the potential contribution of the use of three-dimensional (3D) ultrasound on repeatability, reproducibility and agreement of two-dimensional (2D) and 3D-derived measurements.Materials and methodsTwo observers (one senior and one junior) measured head circumference (HC), abdominal circumference (AC) and femur length (FL) in 33 fetuses (20 to 40 weeks of gestation). Each observer performed two series of 2D measurements and two series of 3D measurements (i.e., measurements derived from triplane volume processing). Measurements were converted into Z-scores according to gestational age. Variability between the different series of measurements was studied using Bland–Altmann plots and intra-class correlation coefficients (ICC).ResultsAgreement with the 2D measurements of the senior observer was higher in 3D than in 2D for the junior observer (systematic differences of −0.4, −0.2 and −0.8 Z-score vs. −0.1, −0.1 and −0.6 for HC, AC and FL on 2D and 3D datasets, respectively). The use of 3D ultrasound improved junior observer repeatability (ICC = 0.94, 0.88, 0.90 vs. 0.94, 0.94 and 0.96 for HC, AC and FL in 2D and 3D, respectively). The reproducibility was greater using the junior observer 3D datasets (ICC = 0.75, 0.60 and 0.45 vs. 0.79, 0.89 and 0.63 for HC, AC and FL, respectively).ConclusionThe use of 3D ultrasound improves the consistency of the measurements performed by a junior observer and increases the overall repeatability and reproducibility of measurements performed by observers with different levels of experience.     

Nonlinear analysis of spatial vision using first-and-second-order volterra transfer functions measurement

The harmonic input method of nonlinear system identification is modified to allow the Volterra series approach to be used for psychophysical investigation of various aspects of human pattern vision in the spatial frequency domain. While it is well known that only one modulation transfer function provides a complete characterization of a linear system, a number of multidimensional transfer functions are needed to identify a nonlinear system. We have shown, that so far as the contrast sensitivity to sine-wave gratings may be used for an empirical estimate of the first-order modulation transfer function of the human visual system, the contrast sensitivity to difference harmonics may be used as an empirical estimate of the second-order modulation transfer function.

A difference harmonic arises from a mixture of two sine-wave gratings resulting from the nonlinearity of the visual system. Difference harmonic, experienced as some periodic beatlike structure, may still be observed if frequencies of the component gratings are higher than the maximum visual acuity.

The visibility of the low-frequency beatlike pattern produced by pairs of sine-wave gratings, which themselves are of spatial frequencies too high to be resolved, could be accounted for either by a difference frequency distortion product (Burton, 1973) or by a special beat detector (Derrington & Badcock, 1985). We found that increasing the contrast of one component grating may be compensated for by reducing the contrast of the other component grating, the beatlike pattern being at threshold. This is exactly what would be expected if the beatlike pattern is detected because of the difference harmonics produced by nonlinearity of the visual system.

We have determined contrast thresholds for the difference harmonics which occur between two unresolved different spatial frequencies. The contrast sensitivity function for difference harmonics was found to have a marked similarity both in the shape and position of peak sensitivity to the contrast sensitivity function for single sine-wave gratings. Another important characteristic of the contrast sensitivity function for difference harmonics is that it depends only on the frequency difference, Δf = f₁ − f₂, rather than on the value of either f₁ or f₂.

All this indicates that a difference harmonic arises from local nonlinearities in the visual system. More specifically, the visual system may be represented as a cascade system, composed of a linear system with transfer function O(f) followed by a nonlinear element, r(·), without spatial spread in cascade with another linear system with transfer function P(f). The nth order transfer function of this cascade system, H_n(f₁,...,f_n) can be expressed in the following way: H_n(f₁,...,f_n) = a_nO(f₁)P(f₁ + ... + f_n) where a_n is the nth coefficient in the Taylor series expansion for the nonlinear function r(·). It follows from this that the measurement of the first- and second-order transfer functions is sufficient to determine O(f) and P(f). We have derived the estimates of cO(f) and P(f) from contrast sensitivity functions for single sine-wave gratings and difference harmonics by the least squares method.     

Effect on Mn2+ on permeability properties of frog skin

Summary Mn²⁺ added to the inner bathing solution of frog skin caused a transient increase in potential difference (PD) and a decrease in total skin conductance and mannitol influx. Net Na flux and short-circuit current (Is. c.) were also reduced, the isotopic net flux being reduced more than Is. c. This observed discrepancy appears to be the result of Cl^– retention in the outer medium since it was not observed when the skin was bathed in a sulfate-substituted chloridefree solution. The effect of Mn²⁺ on the inner side of the frog skin appears to be due to a reduced permeation of Na⁺ and Cl^– through the outer barrier of the skin.Addition of Mn²⁺ to the outer solution bathing the frog skin caused an increase in PD and a smaller increase in Is. c. These changes were not associated with alterations in the fluxes of Na⁺ or mannitol and were observed only when chloride was present in the bathing solutions. The effect of Mn²⁺ on this side of the frog skin may therefore be due to a net retention of Cl^– in the outer solution.