Understanding the dipyrone oxidation allying electrochemical and computational approaches.

Electroanalytical methodology by boron-doped diamond electrode (BDDE) associated to the square-wave voltammetry (SWV) for the determination of hydrolyzed dipyrone (DIP) in commercial formulations, raw natural waters and in human urine was developed. Through cyclic voltammetry (CV), it was shown that the oxidation of the DIP on the BDDE was irreversible with diffusional control. Computational studies suggested that the oxidation mechanism of DIP occurred with participation of two electrons and one proton. The analytical curves were obtained for concentrations of DIP ranging from 1.0 × 10-6 to 6.5 × 10-5 mol L-1 (r = 0.9994). The values of detection limit (LOD) and quantification limit (LOQ) of DIP were calculated from SWV and found to be 2.6 × 10-7 mol L-1 and 8.8 × 10-7 mol L-1. The methodology was effectively applied to real samples with the values of calculated recoveries varying between 91.0% and 117.3% and validated by iodometric titration experiments whose values were between 93.3% and 106.9%. The proposed methodology with BDDE represents an alternative tool and it has advantageous, such as very easy handling, low cost, no need for modification, low detection limit. Furthermore, it can be used for the routine analysis of DIP in different real samples.

Unexpected diminished innervation of epidermis and dermoepidermal junction in lichen amyloidosus.

BACKGROUND: Lichen amyloidosus is a localized, chronic, pruritic skin disease characterized by deposition of amyloid in the papillary dermis. The pathogenesis of the pruritus of lichen amyloidosus is largely unknown. OBJECTIVES: To determine any change in the nerve fibre density in lichen amyloidosus lesions as an explanation for itch. METHODS: Using an antibody to protein gene product (PGP) 9.5, the immunohistochemical analysis of the skin biopsies of 30 Hispanic patients with clinicopathologically proven lichen amyloidosus and of 11 healthy Hispanic controls matched for age, sex and site was performed. RESULTS: Unexpectedly, the mean amount of PGP9.5 stain, a measure for nerve fibre amount, for the healthy controls was higher than the lichen amyloidosus group both in the epidermis (P < 0.0019) and dermoepidermal junction (P < 0.0064). No change was observed in the papillary dermis. Furthermore, the proportion of area covered by PGP9.5 showed a significant decrease in the epidermis (P < 0.0024) and dermoepidermal junction (P < 0.0075) in lichen amyloidosus compared with healthy controls. Age, gender and body site were found not to be influencing factors in nerve fibre amounts in lichen amyloidosus samples. CONCLUSIONS: We speculate that the severe pruritus observed in lichen amyloidosus might be the result of the hypersensitivity of the remaining nerve fibres as a response to an unexplained neurodegeneration of the absent nerve fibres.

Deficient dietary vitamin K intake among elderly nursing home residents in Hong Kong.

There is strong evidence supporting the importance of vitamin K in bone health and the aetiological role of vitamin K deficiency in osteoporosis. In view of the common occurrence of osteoporosis among older subjects in Hong Kong, we have studied the dietary vitamin K intakes in 100 residents of a nursing home (43 men, 57 women; median age 81.0 years) and 88 free-living subjects attending a day care centre (13 men, 75 women; median age 71.5 years). The subjects were interviewed and the average vitamin K intake in the preceding week was estimated, using a diet recall questionnaire modified from our previous surveys of dietary patterns in local Chinese people. The median vitamin K intake was much lower in nursing home residents than in free-living subjects (4.50 vs 488.09 microg/day or 0.13 vs 8.74 microg/kg/day, P<0.001). An intake that was below the recommended daily intake was far more common among nursing home residents (86.0 vs 11.4%, P < 0.001). Among nursing home residents, there was a negative correlation between age and vitamin K intake (r = -0.217, P = 0.030), but there was a positive correlation between body weight and vitamin K intake (r = 0.244, P = 0.015). No such relationship was seen among free-living subjects. Elderly nursing home residents in this study generally had a poor dietary vitamin K intake and might therefore be predisposed to osteoporosis. The importance of green leafy vegetables as a rich source of vitamin K should be emphasised.