Study of NBT-Pluronic F-127 Gels as 1D UV Radiation Dosimeters for Measurement of Artificial Light Sources

This work reports on radiochromic dosimeters for 1D UV light measurements. The dosimeter is composed of a 25% Pluronic F–127 that forms a physical gel matrix and nitro blue tetrazolium chloride (NBT) as a radiation-sensitive compound. This dosimeter was exposed to UVA, UVB and UVC radiation, and the radiochromic reactions were followed with reflectance spectrophotometry including changes in light reflectance and color coordinates in the CIELAB color system. The exposition of dosimeters to all UV radiation caused color changes from pale yellow to dark violet, and its intensity increased with increasing absorbed dose. The effects of NBT concentration and UV radiation type on the dose–response of the dosimeters were also examined. The results obtained reveal that the dosimeters are the least sensitive to irradiation with UVC and the most sensitive to irradiation with UVB (e.g., dosimeter with 2 g/dm³ of NBT was characterized by the following parameters: the threshold dose 0.1 J/cm²; the dose sensitivity −5.97 ± 0.69 cm²/J; the linear dose range 0.1–2.5 J/cm²; the dynamic dose range was equal to 0.1–3 J/cm²). The results obtained reveal that the NBT–Pluronic F–127 dosimeters can be potentially useful as 1D sensors for artificial UV radiation sources measurements.

The prevalence and risk factors of vitamin D inadequacy among male athletes in Kuwait: A cross-sectional study

The aim of this study was to determine the prevalence of vitamin D inadequacy in male athletes living in Kuwait, and to assess its relationship with possible risk factors including body composition, lifestyle and fasting Ramadan. A Cross- sectional study was conducted on a total of 250 male athletes registered in official sports clubs in Kuwait were included. Blood tests, anthropometric measurements and a lifestyle questionnaire were performed. Serum 25(OH)D level was used as a measure of vitamin D status. Vitamin D inadequacy was defined as serum 25(OH)D < 75 nmol/L, inadequate levels were further classified as vitamin D insufficiency (50-75 nmol/L), vitamin D deficiency (<50 nmol/L) and severe deficiency (<25 nmol/L). Thirty-six percent of the sample were football players, 13% were futsal players and the rest were players of 15 different outdoor and indoor sports. A prevalence of 83% of vitamin D inadequacy (< 75 nmol/L) was observed in male athletes in Kuwait, of which 23% had severe deficiency (< 25 nmol/L). The prevalence increased from 80% (n = 130) before Ramadan to 90% (n = 79) after Ramadan. There was a significant positive association between serum 25(OH)D concentrations and vitamin D intake (p < 0.001). Serum 25(OH)D concentrations were significantly inversely associated with risk of injuries (p = 0.008) and with the concentrations of parathyroid hormone (PTH) (p = 0.029). No statistically significant associations between 25(OH)D concentrations and sun exposure, physical activity or anthropometric levels were found. Similar to other studies in the Middle East, we found that healthy male athletes in Kuwait have a high prevalence of vitamin D inadequacy. The results of this study suggest the need for regular supplement intake and vitamin D awareness campaigns for athletes in Kuwait. More research is needed to assess the effect of Ramadan.

Asthma prevalence associated with geographical latitude and regional insolation in the United States of America and Australia

BACKGROUND

It has been proposed that vitamin D deficiency may be responsible for an increase in the prevalence of allergic diseases and asthma worldwide. Human ability to generate physiologically required quantities of vitamin D through sun exposure is decreasing with increasing geographical latitude.

OBJECTIVES

Considering that vitamin D deficiency is usually due to lack of outdoor sun exposure, this study is designed to test the hypothesis that a higher prevalence of asthma should be expected at high relative to low geographical latitudes.

METHODS

Linear regression analyses are performed on asthma prevalence in the U.S. adult population vs. geographical latitude, insolation, air temperature, and air pollution (PM(2.5)) for 97 major metropolitan/micropolitan statistical areas of the continental United States of America and on general population asthma prevalence vs. geographical latitude in eight metropolitan areas of Australia.

RESULTS

A 10° change in geographical latitude from southern to northern regions of the Eastern Seaboard is associated with a 2% increase in adult asthma prevalence (p<0.001). Total insolation in winter months is almost as strong as latitude in its ability to explain the observed spatial variation in the prevalence of asthma (r(2) = 0.43; p<0.001). Similar results are obtained using the Australian data (r(2) = 0.73; p<0.01), suggesting a consistent association between the latitude/insolation and asthma prevalence worldwide.

CONCLUSIONS

The results of this study suggest that, as a known modulator of the immune response closely linked with the geographical latitude and erythemal UV irradiation, vitamin D may play an important role in the development/exacerbation of asthma.

Solar ultraviolet-B irradiance and vitamin D may reduce the risk of septicemia

The primary features of the epidemiology of septicemia in the United States include highest rates in winter and the Northeast, lowest in fall and in the West; higher rates among African Americans than white Americans; a rapid increase in incidence with age; comorbidity with several chronic and infectious diseases; and a rapid increase in incidence rate starting in the early 1980s. This article reviews the literature on the epidemiology of septicemia in the United States, along with the roles of solar ultraviolet-B (UVB) and vitamin D3 related to the more important features. Solar UVB doses in summer are highest in the Southwest and lowest in the Northeast. Serum 25-hydroxyvitamin D [25(OH)D] levels are highest in summer, lowest in winter. African Americans have much lower 25(OH)D levels than those of white Americans. Serum 25(OH)D levels decline rapidly with advancing age. The risk of diseases comorbid with septicemia are generally inversely correlated with serum 25(OH)D levels. Sun-avoidance messages may have led to lower population levels of 25(OH)D, although prevalence of antibiotic-resistant bacteria may have increased. Previous reports have shown that 1,25-dihydroxyvitamin D upregulates human cathelicidin, LL-37, which has antimicrobial as well as antiendotoxin activity. The general agreement between the epidemiology of septicemia in the United States and the variations of solar UVB and the effects of vitamin D supports the hypothesis that both play important roles in reducing the risk of septicemia. Further study is warranted to evaluate this hypothesis.

Hypothesis--ultraviolet-B irradiance and vitamin D reduce the risk of viral infections and thus their sequelae, including autoimmune diseases and some cancers

Many viral infections reach clinical significance in winter, when it is cold, relative humidity is lowest and vitamin D production from solar ultraviolet-B irradiation is at its nadir. Several autoimmune diseases, such as multiple sclerosis, type 1 diabetes mellitus and asthma, are linked to viral infections. Vitamin D, through induction of cathelicidin, which effectively combats both bacterial and viral infections, may reduce the risk of several autoimmune diseases and cancers by reducing the development of viral infections. Some types of cancer are also linked to viral infections. The cancers with seemingly important risk from viral infections important in winter, based on correlations with increasing latitude in the United States, an index of wintertime solar ultraviolet-B dose and vitamin D, are bladder, prostate, testicular and thyroid cancer, Hodgkin's and non-Hodgkin's lymphoma, and, perhaps, gastric cancer. The evidence examined includes the role of viruses in the etiology of these diseases, the geographic and seasonal variation of these diseases, and the time of life when vitamin D is effective in reducing the risk of disease. In general, the evidence supports the hypothesis. However, further work is required to evaluate this hypothesis.