Association between lactic acid sting test scores, self-assessed sensitive skin scores and biophysical properties in Chinese females.

BACKGROUND: Lactic acid sting test (LAST) is a classical method to identify sensitive skin. However, some subjects with self-perceived sensitive skin are negative for LAST. OBJECTIVE: To determine whether LAST scores are associated with specific phenotype of sensitive skin. METHODS: A total of 292 subjects with self-perceived sensitive skin were enrolled in this study. The Sensitive Scale was used to evaluate the severity of burning, stinging, itching, tautness, erythema and scaling based on 0-10 scale scores. In addition to the assessment of LAST scores, epidermal biophysical properties were measured using an MPA system. RESULTS: The Sensitive Scale scores of stinging, itching, tautness and scaling were significantly different between the LAST-positive and -negative groups. However, burning and erythema scores did not differ between the LAST-positive and -negative groups. LAST scores were positively correlated with the Sensitive Scale scores for stinging, itching, tautness and scaling, but not for burning and erythema scores. Moreover, LAST scores negatively correlated with stratum corneum hydration, but positively with transepidermal water loss (TEWL) rates. CONCLUSIONS: Lactic acid sting test scores positively correlated with TEWL rates. LAST scores could be used to identify subjects with sensitive skin characterized mainly by stinging and itching, but not those mainly by burning and erythema.

CONTEXTE: Le test de la piqûre d'acide lactique (LAST) est une méthode classique pour identifier les peaux sensibles. Cependant, certaines personnes s'évaluant ayant une peau sensible sont négatifs au test LAST. OBJECTIF: Déterminer si le score du LAST est associé à un phénotype spécifique de peau sensible. MÉTHODES: Au total, 292 personnes s'évaluant ayant une peau sensible ont été inclus dans cette étude. L'échelle de sensibilité a été utilisée pour évaluer la sévérité de la brûlure, du picotements, de la démangeaison, de la tension, de l'érythème et des desquamations basée sur une échelle de 0-10. En plus de l'évaluation du score LAST, les propriétés biophysiques épidermiques ont été mesurées à l'aide d'un système MPA. RÉSULTATS: Les scores de l'échelle de sensibilité pour le picotement, les démangeaisons, la tension et la desquamation étaient significativement différents entre la groupe LAST positif et celle du LAST négatif. Cependant, les scores de la brûlure et de l'érythème n'étaient pas différents entre les deux groupes. Le score LAST était positivement corrélé avec les scores de l'échelle de sensibilité du picotement, des démangeaisons, de la tension et des desquamations, mais pas pour la brûlure et l'érythème. En plus, les scores LAST étaient négativement corrélés avec l'hydratation du stratum corneum, mais positivement corrélés avec le taux de perte en eau transépidermique (TEWL). CONCLUSIONS: Les scores LAST étaient corrélés positivement avec le taux de perte en eau transépidermique. Les scores LAST pourraient être utilisés pour identifier les personnes avec la peau sensible caractérisée principalement le picotement et les démangeaisons, mais pas la brûlure et l'érythème.

A technique for measuring dynamic friction coefficient under impact loading.

We develop a novel setup based on the split Hopkinson pressure bar technique to test the dynamic friction coefficient under impact loading. In the setup, the major improvement is that the end of the incident bar near the specimen is wedge-shaped, which results in a combined compressive and shear loading applied to the specimen. In fact, the shear loading is caused by the interfacial friction between specimen and bars. Therefore, when the two loading force histories are measured, the friction coefficient histories can be calculated without any assumptions and theoretical derivations. The geometry of the friction pairs is simple, and can be either cuboid or cylindrical. Regarding the measurements, two quartz transducers are used to directly record the force histories, and an optical apparatus is designed to test the interfacial slip movement. By using the setup, the dynamic friction coefficient of PTFE/aluminum 7075 friction pairs was tested. The time resolved dynamic friction coefficient and slip movement histories were achieved. The results show that the friction coefficient changes during the loading process, the average data of the relatively stable flat plateau section of the friction coefficient curves is 0.137, the maximum normal pressure is 52 MPa, the maximum relative slip velocity is 1.5 m/s, and the acceleration is 8400 m(2)/s. Furthermore, the friction test was simulated using an explicit FEM code LS-DYNA. The simulation results showed that the constant pressure and slip velocity can both be obtained with a wide flat plateau incident pulse. For some special friction pairs, normal pressure up to a few hundred MPa, interfacial slip velocities up to 10 m/s, and slip movement up to centimeter-level can be expected.

Improved expanding ring technique for determining dynamic material properties.

An improved expanding ring experimental technique has been described to determine dynamic material properties under conditions approximating uniform one-dimensional tensile loading. There are mainly explosive expanding ring technique and electromagnetic expanding ring technique currently, for which exist many limitations in practical applications. The work reported herein is an attempt to overcome this difficulty by lateral efficiency loading produced by projectile, made of low-density material, impacting the same material filling. The lateral efficiency loading is a convenient and effective method, which allows materials to be in uniform uniaxial stress conditions at a high stress rate. The procedure is illustrated by experiments performed on 1100-0 aluminum rings.

A technique for combined dynamic compression-shear test.

It is critically important to study the dynamic response of materials under a combined compression-shear loading for developing constitutive laws more accurately and fully. We present a novel technique to achieve the combined compression and shear loadings at high strain rates. The main apparatus consists of a strike bar, an incident bar, and two transmission bars. The close-to-specimen end of the incident bar is wedge-shaped with 90°. In each experiment, there are two identical specimens, respectively, agglutinated between one side of the wedge and one of transmission bars. When a loading impulse travels to specimens along the incident bar, because of the special geometrical shape, the specimen-incident bar interface gets an axial and a transverse velocity. Specimens endure a combined compression-shear loading at high strain rates. The compression stress and strain of the specimens are deduced from signals recorded by strain gages mounted on the bars. The shear stress is measured by two piezoelectric transducers of quartz (Y-cut with rotation angle 17.7°) embedded at the close-to-specimen end of transmission bars; the shear strain is measured with a novel optical technique, which is based on the luminous flux method. An analytic model was proposed and validated by the numerical simulations. The simulation results yield good agreement with the analytic results. The proposed technique was then validated through experiments carried out on lead specimens, by comparing experimental results with that of the split Hopkinson pressure bar experiments.

[An experimental study of inhibition on lactation in fluorosis rats].

The effect of fluorosis on lactation, lactotroph function and ultrastructure were studied in lactating rats. The results were as follows: 1) Inhibition of lactation in lactating rats with chronic fluorosis was assessed by stunting growth of pups and decrease in the amount of milk suckled by pups in 30 min. Metoclopramide, a blocker of dopamine receptor, could improve lactation in these rats. 2) During chronic fluorosis serum PRL level was decreased, however, PRL content in pituitary was increased. Electronmicroscopic examination showed accumulation of large mature secretory granules and appearance of extremely large abnormal secretory granules in lactotroph cytoplasma. These findings indicate that hormone release of pituitary lactotrophs is obstructed in lactating rats with fluorosis, and the toxic effect of fluoride is mediated by an enhanced function of dopaminergic system in hypothalamus.

[Pharmacokinetics of norethindrone enanthate 200 mg after intramuscular injection in 25 Chinese women].

Pharmacokinetic profile was studied in 25 healthy fertile Chinese female volunteers after im norethindrone enanthate (NET-EN) 200 mg. The results were compared with the data from British women in our previous paper. Following a single im NET-EN 200 mg, the times to reach peak levels of NET-EN and NET were 4.0 +/- 2.8 d and 5.4 +/- 2.0 d, and their peak values were 5.0 +/- 1.8 and 12.6 +/- 0.9 ng.ml-1, respectively. Mean elimination T1/2 of NET was significantly longer than that of NET-EN. Mean apparent elimination T1/2 were 14.8 +/- 3.8 d for and 11.4 +/- 5.7 d for NET-EN. The elimination rate of NET in Chinese women was significantly slower than that in British women. There was no significant ethnic difference in absorption kinetics of NET and NET-EN.

The effects of long-term using once-a-month injectable contraceptive norethisterone enanthate/estradiol valerate on coagulation in the Chinese.

Sixty-four Chinese women were studied for the effects of injecting once-a-month contraceptive norethisterone enanthate/estradiol valerate between 2 to 4 1/2 years on certain coagulation and fibrinolytic parameters, and 59 women not receiving any steroidal contraception were controls. In both groups there was no significant change in PT, fibrinogen, factor X activity, AT III antigen, AT III activity and fibrinolytic activity expressed by euglobulin lysis time. There was no significant difference in mean levels of factor VIIIR:Ag between the two groups, although a sub-group women in treatment group had higher than accepted levels of factor VIIIR:Ag.

Hemostatic changes in women using a monthly injectable contraceptive for one year.

The effect of consecutively injecting a one-a-month contraceptive (norethisterone enantate 50 mg with estradiol valerate 5 mg) for one year on haematological parameters was evaluated in 42 Chinese women. The healthy volunteers were randomly allocated to either the treatment group (22) or a control group (20). Blood samples were collected in the follicular and luteal phases of a pretreatment cycle, on days 28 +/- 3 after the 1st, 3rd, 6th, 12th injections and in the luteal phase of the post-treatment cycle. The results showed that in both groups, prothrombin time and fibrinogen fluctuated significantly, and leucocyte count was not significantly changed during the whole course. Factor VIII-related antigen and antithrombin III (AT-III) antigen showed minor changes, although in the 3rd treatment cycle, the differences between the two groups in both parameters reached statistical significance. A progressive and significant decrease in Factor X and AT-III functional activity occurred with the monthly injectable treatment, decreasing by about 14% and 20%, respectively, after 12 months of treatment. Haemoglobin levels were increased in the treatment group after the 3rd injection and remained at the higher level during the study period. It is doubtful whether these changes are likely to be of clinical relevance.

[A clinical report of norethisterone-3-oxime-acetate vacation pill].

This paper reported the clinical application of Norethisterone-Oxime-Acetate used as a "vacation" pill. The result indicated that pregnancy could be prevented in women who received this drug orally when they themselves or their husband came home on leave. A dose of 2 mg was administered for women on the 1st day when the couples live together, then followed by 1 mg daily successively and an additional pill was given on the morning next to the end of the leave. A high efficacy of 99.75% in terms of cycles proved in 604 women with 825 treated cycles of 604 women. The changes in menstrual cycles, the duration of menstrual bleeding and the amount of flow after treatment were very slight. The incidence of the intermenstrual bleeding and withdrawal bleeding were 2.16%. The author's observation showed that Norethisterone-oxime-Acetate is an active contraceptive pill and possesses the advantages of not only high efficacy, low side effect, but also convenience in use.