The analysis of scalp irritation by coacervates produced in hair shampoo via FTIR with focal plane array detector, X-ray photoelectron microscopy and HaCaT cells.

OBJECTIVE: Coacervates are inevitably formed on scalp on using hair washing products. Our goal was to analyse the coacervates in detail to identify the part responsible for scalp stimulation. METHODS: Shampoo that increases coacervate formation was applied to in vitro skin and was washed. The residue was then analysed using Fourier transform infrared spectroscopy-focal plane array (FTIR-FPA) and X-ray photoelectron microscopy (XPS). And HaCaT cells were used for irritant test of coacervate. RESULTS: Through this research, it was confirmed that the coacervate was a macromolecule structurally similar to a cationic polymer and contains an anionic surfactant. Its anionic surfactant was structurally semi-stable so that it released onto scalp when it absorbs moisture. CONCLUSION: Coacervate releases sulphate bonding into the matrix when it is exposed to water. Thus, the scalp stimulation would be expected.

Regional and seasonal differences in skin irritation and neurosensitivity in Chinese and South Korean women.

BACKGROUND: China has a great variety of geographical and climatic conditions, and several cultural differences exist within the country; thus, understanding the regional and seasonal differences that cause skin sensitivities in this country is important. OBJECTIVE: The aim of this study was to assess skin sensitivity of women from six cities in China and from South Korea during the winter and summer seasons to aid the development of suitable and effective dermatological products. METHODS: This multicentre study included 754 healthy female volunteers, and was conducted in the winter (between January and March) and summer (between June and July) of 2011. Patch tests were performed using 0.5% sodium lauryl sulphate (SLS) aqueous solution and 0.15% retinol in 1,3-butylene glycol on the back of the volunteers. Simultaneously, stinging tests were performed on their cheeks by using 5% lactic acid solution and 0.001% capsaicin solution, each in a negative control vehicle (distilled water and 10% ethanol solution, respectively). RESULTS: The patch test results showed that the subjects in Beijing and Shenyang were more sensitive to SLS, retinol and lactic acid in the winter than were those in Guangzhou, Shanghai, Wuhan, Chengdu and South Korea. The stinging test results revealed that the subjects in Beijing were more neurosensitive to lactic acid in the winter; however, during the same season, the subjects from Shanghai and Guangzhou were significantly more neurosensitive to capsaicin. CONCLUSION: Our observations indicate that skin sensitivity differs considerably between women from different parts of China and South Korea. We recommend that these differences be considered during the development of cosmetic products in these countries.

Ethnic differences in objective and subjective skin irritation response: an international study.

BACKGROUND: Due to global marketing in the cosmetics industry, it is important to assess ethnic population susceptibility when evaluating the safety of cosmetic products or chemicals. OBJECTIVES: To investigate ethnic variations in skin irritation response to positive irritants. METHODS: Clinical testing was performed in four countries on two ethnic groups - Asian and Caucasian. We performed patch tests on the subjects' back with 0.5% aqueous sodium lauryl sulfate (SLS) and 0.15% retinol prepared in 1,3-butylene glycol. Stinging tests were performed using 5% aqueous lactic acid and 0.001% (w/v) capsaicin prepared in 10% ethanol solution separately. RESULTS: The incidence of self-perceived skin sensitivity was similar in the two ethnic groups. However, the incidence of adverse skin reaction to cosmetics appeared significantly higher in Asian (33.0%) than in Caucasian subjects (11.3%). For standard positive irritants such as 0.5% aqueous SLS solution, Asian subjects showed significantly higher scores than Caucasian subjects. The incidence of positive reaction to the 0.15% retinol patch test tended to be higher in Asian than in Caucasian subjects. Our data also showed that neurosensitivity to 5% lactic acid and 0.001% capsaicin was higher in Asian than in Caucasian subjects. CONCLUSION: Although self-reported skin sensitivity does not appear to differ according to ethnicity, there are ethnic differences in objective and subjective skin irritation responses to several standard positive materials.

The influence of alkane chain length on the skin irritation potential of 1,2-alkanediols.

Several studies have reported that 1,2-alkanediols show increasing anti-microbial activity as their alkane chain length increases. However, there are no reports on the influence of alkane chain length on the skin irritation potential of 1,2-alkanediols. To investigate the influence of alkane chain length on the skin irritation potential of 1,2-alkanediols. The objective and subjective (sensory) skin irritation potentials of five 1,2-alkanediols - 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol and 1,2-decanediol - were evaluated. We also estimated percutaneous absorption by measuring in vitro skin penetration using a Franz diffusion cell system. Like anti-microbial activity, sensory irritation potential increased as alkane chain length increased, most likely due to increasing membrane interference and/or intrinsic toxicity of 1,2-alkanediols. 1,2-Hexanediol showed the lowest objective skin irritation potential, which increased when the alkane chain length decreased or increased. Furthermore, percutaneous absorption negatively correlated with the alkane chain length of 1,2-alkanediols. These results show that a lower skin absorption potential is not indicative of a low skin irritation potential. Our results suggest that the factors and processes involved in skin irritation potential are complex and that skin irritation potential is influenced by intrinsic toxicity and the potential for penetration or integration in the lipid bilayer.

Suppurative gastritis in BALB/c mice infected with Listeria monocytogenes via the intragastric route.

Suppurative gastritis was demonstrated in BALB/c mice 3 days after intragastric inoculation with 10(9) organisms of Listeria monocytogenes strain ATCC19113 (serotype 3). Also tested were four other strains of mice (C3H, C57BL/6, FVB and ICR) and three other strains of L. monocytogenes (HPB 3 [serotype 4b], HPB 410 [serotype 1/2a] and HPB 503 [serotype 1/2b]). After inoculation with ATCC19113 the numbers of bacteria found in the stomach wall were greater in C57BL/6 and ICR mice than in C3H and FVB mice; moreover, the gastritis produced in BALB/c and C57BL/6 mice was more severe than that produced in the other mouse strains. The gastritis produced in BALB/c mice with L. monocytogenes HPB 3, HPB 410 and HPB 503 was much more severe than that produced by ATCC19113. The inflammatory response occurred in the lamina muscularis and mucosa of the fundus. Massive necrosis of the gastric epithelium was observed, and there was oedema in a large part of the mucosal layer of the fundus. In addition, the submucosal layer was apparently expanded due to oedema, and in the cardia, the mucosal layer had become thin and flattened. Immunohistochemically, a polyclonal antibody against Listeria spp. produced labelling in areas of the gastric mucosa in which there was an inflammatory response and gastric epithelial necrosis.

Changes in mandibular masticatory movements after insertion of nonworking-side interference.

To investigate the influence of nonworking-side interferences on mandibular masticatory movements and signs and symptoms of dysfunction of the masticatory system, an experimental balancing-side interference was introduced in 12 healthy subjects for 1 week. The individual response to the interference varied substantially. However, some of the movement variables were significantly changed immediately after insertion, but an adaptation of the neuromuscular system to the interference was evident at the end of the experimental period.

The association of knee injury and obesity with unilateral and bilateral osteoarthritis of the knee.

The strength of the associations of knee injury and obesity with osteoarthritis of the knee was studied for 3,885 adults aged 45-74 years who received knee x-rays in the First National Health and Nutrition Examination Survey, 1971-1975. Bilateral osteoarthritis was more prevalent (5%) than unilateral osteoarthritis (2%). Bilateral osteoarthritis was twice as prevalent in women as in men; however, there was no sex difference in the prevalence of unilateral osteoarthritis. Odds ratios calculated by means of polychotomous logistic regression indicated that obesity, knee injury, and age were significantly associated with both unilateral and bilateral knee osteoarthritis. Obesity was a stronger predictor of bilateral osteoarthritis than was knee injury (odds ratio (OR) = 6.6 for obesity, 3.5 for right knee injury, and 3.0 for left knee injury; 95% confidence interval (CI) 4.71-9.18, 1.80-6.83, and 1.51-6.11, respectively). Knee injury was a stronger predictor of unilateral osteoarthritis than was obesity (OR = 3.4 and 2.4 for obesity in the right and left knee, respectively (95% CI 1.55-7.29 and 0.96-5.75) and OR = 16.3 and 10.9 for injury in the right and left knee, respectively (95% CI 6.50-40.89 and 3.72-31.93]. These findings suggest that different pathogenetic processes may exist for unilateral and bilateral knee osteoarthritis.