Lower melanin content in the skin of type 1 diabetic patients and the risk of microangiopathy.

BACKGROUND: Various skin diseases are commonly observed in diabetic patients. Typical biophysical properties of diabetic skin such as lower skin elasticity, decreased water content in stratum corneum, increased itching and sweating disturbances are reported. The aim of the study was to examine the distribution and intensity of skin pigmentation in diabetic patients in correlation with the metabolic control and with presence of microangiopathy. MATERIAL AND METHODS: The study was conducted on 105 patients (42 men and 63 women, median age 31), with type 1 diabetes (DM1). The control group of 53 healthy individuals (22 men and 31 women) was age- and sex-matched. Skin pigmentation was measured at 3 different locations of the body (cheek, dorsal surface of a forearm and dorsal surface of a foot) using Mexameter® MX 18. We calculated melanin index (MI) by the meter from the intensities of absorbed and reflected light at 880 nm. RESULTS: Patients with DM1 had lower MI on the foot (173.2 ± 38.8 vs. 193.4 ± 52.7, p=0.016) as compared to controls. In the univariate analysis cheek MI was negatively related to HbA1c level (ß=-4.53, p=0.01). Forearm MI was negatively associated with daily insulin dose (ß=-0.58, p=0.01), BMI (ß=-3.02, p<0.001), waist circumference (ß=-0.75, p=0.009), serum TG concentration (ß=-18.47, p<0.001) and positively with HDL cholesterol level (ß=15.76, p=0.02). Diabetic patients with hypertension had lower foot MI values (ß=-18.28, p=0.03). Lower MI was associated with the presence of diabetic neuropathy (ß=-18.67, p=0.04) and retinopathy (ß=-17.47, p=0.03). CONCLUSIONS: In conclusion, there seems to be loss of melanocytes in type 1 diabetes. The melanin content is related to glycemic control of diabetes and obesity. The lower melanin content the higher possibility of microangiopathy. This is a first report in the literature devoted to distribution of melanin in the skin of type 1 diabetic patients.

Adhesion and proliferation of cultured human aortic smooth muscle cells on polystyrene implanted with N+, F+ and Ar+ ions: correlation with polymer surface polarity and carbonization.

Physicochemical surface properties and biocompatibility were studied in polystyrene (PS) implanted with 150 keV N+, F+ and Ar+ at doses ranging from 1 x 10(12) to 1 x 10(15) cm-2. Adhesion and proliferation of cultured human aortic smooth muscle cells (SMCs) on ion implanted PS were thoroughly examined for dependence on implanted dose and ion species and in close relation to polymer surface oxidation, surface polarity, concentration of conjugated double bonds and sheet resistivity. The surface polarity of PS was a smooth, increasing function of the implanted dose. However, the dependence of SMC population density on the implanted dose was found to be more complicated. After 18 h cultivation time (i.e. when only cell attachment and spreading took place), the number of adhered SMCs and their degree of spreading first increased with increasing ion dose, and after reaching a maximum at the dose of 5 x 10(12) cm-2, they decreased to original values. For doses above 5 x 10(14) cm-2, an increase in SMC population density and spreading was again observed. The first maximum in cell adhesion can be explained by slight increases in the surface polarity and wettability, optimal for cell adhesion, and the second maximum by progressive carbonization of the PS surface. After 96 h cultivation time (i.e. when the cells proliferated intensively), the dramatic dependence of the SMC population density on implanted dose is mostly smeared out. This observed dependence of SMC attachment, spreading and subsequent proliferation on the implanted dose was similar in all three ion species, but highest cell densities were achieved on PS implanted with F+ ions.