Vitamin D

Ohne Zusammenfassung     

Synthesis of Deuterium-Labeled Vitamin D Metabolites as Internal Standards for LC-MS Analysis

Blood levels of the vitamin D₃ (D₃) metabolites 25-hydroxyvitamin D₃ (25(OH)D₃), 24R,25-dihydroxyvitamin D₃, and 1α,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) are recognized indicators for the diagnosis of bone metabolism-related diseases, D₃ deficiency-related diseases, and hypercalcemia, and are generally measured by liquid-chromatography tandem mass spectrometry (LC-MS/MS) using an isotope dilution method. However, other D₃ metabolites, such as 20-hydroxyvitamin D₃ and lactone D₃, also show interesting biological activities and stable isotope-labeled derivatives are required for LC-MS/MS analysis of their concentrations in serum. Here, we describe a versatile synthesis of deuterium-labeled D₃ metabolites using A-ring synthons containing three deuterium atoms. Deuterium-labeled 25(OH)D₃ (2), 25(OH)D₃-23,26-lactone (6), and 1,25(OH)₂D₃-23,26-lactone (7) were synthesized, and successfully applied as internal standards for the measurement of these compounds in pooled human serum. This is the first quantification of 1,25(OH)₂D₃-23,26-lactone (7) in human serum.     

Vitamin D and Skin Cancer

Vitamin D signaling plays a key role in many important processes, including cellular proliferation, differentiation and apoptosis, immune regulation, hormone secretion and skeletal health. Furthermore, vitamin D production and supplementation have been shown to exert protective effects via an unknown signaling mechanism involving the vitamin D receptor (VDR) in several diseases and cancer types, including skin cancer. With over 3.5 million new diagnoses in 2 million patients annually, skin cancer is the most common cancer type in the United States. While ultraviolet B (UVB) radiation is the main etiologic factor for nonmelanoma skin cancer (NMSC), UVB also induces cutaneous vitamin D production. This paradox has been the subject of contradictory findings in the literature in regards to amount of sun exposure necessary for appropriate vitamin D production, as well as any beneficial or detrimental effects of vitamin D supplementation for disease prevention. Further clinical and epidemiological studies are necessary to elucidate the role of vitamin D in skin carcinogenesis.     

Zur Bestimmung von Vitamin D

Ohne Zusammenfassung     

Survey of UV Emissions from Sunbeds in the UK

Increased use of indoor tanning for cosmetic purposes has led to concerns for its impact on the risk of cutaneous cancers. The effects on UVR on skin depend on radiant dose, i.e. combination of irradiance and exposure duration. While a number of studies surveyed accessible emission from sunbeds, majority did not include the information on doses received during tanning sessions. Spectral irradiance of 195 sunbeds in five areas of the United Kingdom was measured in order to assess the radiant doses for comparison with the SED. Erythema weighted irradiance of more than 85% of all tested solaria exceeded 0.3 W m^?2, consistent with the findings of other studies. However, evaluation of radiant doses showed no evidence of increasing exposure per session in the United Kingdom in the last decade despite the increasing sunbed emission levels. Use of sunbeds for cosmetic purposes should be discouraged, with effective enforcement of the ban on under‐18 use, strict control on tanning duration and promotion of information on health risks of sunbed use. Such an integrated approach on safe equipment, safe use, and information should reduce the risk of detrimental impact of sunbed use on public health.     

Vitamin D and Other Differentiation-promoting Agents as Neoadjuvants for Photodynamic Therapy of Cancer

The efficacy of photodynamic therapy (PDT) using aminolevulinic acid (ALA), which is preferentially taken up by cancerous cells and converted to protoporphyrin IX (PpIX), can be substantially improved by pretreating the tumor cells with vitamin D (Vit D). Vit D is one of several “differentiation-promoting agents” that can promote the preferential accumulation of PpIX within the mitochondria of neoplastic cells, making them better targets for PDT. This article provides a historical overview of how the concept of using combination agents (“neoadjuvants”) for PDT evolved, from initial discoveries about neoadjuvant effects of methotrexate and fluorouracil to later studies to determine how vitamin D and other agents actually work to augment PDT efficacy. While this review focuses mainly on skin cancer, it includes a discussion about how these concepts may be applied more broadly toward improving PDT outcomes in other types of cancer.     

液相色谱-串联质谱法测定畜禽肉中维生素D_3和25-OH-D_3

采用液相色谱-串联质谱法测定畜禽肉中维生素D3和25-OH-D3的含量。样品经过皂化,固相萃取净化,正相制备后,Symmetry C18色谱柱分离,采用大气压化学电离源多反应监测模式检测。氘代维生素D3作为内标物。维生素D3和25-OH-D3的线性范围均为5~100μg·L-1,检出限(3S/N)均为0.60μg·kg-1。方法用于猪肉样品的分析,加标回收率在75.0%~97.1%之间,测定值的相对标准偏差(n=6)在1.9%~5.6%之间。     

The Vitamin D Status Among Tibetans

UVB from the sun and intake from food are the only human sources of vitamin D. Tibet is a unique region for comparisons of these sources: (1) it lies at a low latitude and at a high altitude and has very large annual fluences of UVB; (2) the traditional Tibetan food is poor in vitamin D. Blood samples were taken from 63 persons of different age, with different occupations and staying at different places. UVB doses at these places were measured. The samples were analyzed by a standard radioimmune assay for determination of the serum concentration of 25 hydroxyvitamin D (25(OH)D). The main finding was that among nomads, there seems to be severe vitamin D deficiency (serum levels of 25(OH)D < 30 n m ). We tentatively propose that the low level of 25(OH)D of nomads is related to their clothing and sun exposure habits. For persons of other occupations (students, teachers and farmers) the levels are higher, although a significant fraction of these persons also have lower levels than 75 n m , by many regarded as a limit for insufficiency related to a number of negative health conditions. The annual dose of vitamin D-generating UVB is about five times larger in Lhasa than in Oslo. Despite this, the average vitamin D status seems to be similar, except in the case of nomads. This phenomenon is certainly related to food habits. In conclusion, the 25(OH)D status among nomads in Tibet appears to be alarmingly low. However, for people of other occupations the status is more normal.     

Eine Schnellmethode zur Bestimmung von Vitamin D in Gegenwart von Vitamin A

Ohne Zusammenfassung     

HPLC-APCI(+)-MS/MS测定乳制品中的维生素D_2及D_3

建立了一种高效液相色谱-大气压化学电离串联四极杆质谱,正离子监测模式下(HPLC-APCI(+)-MS/MS)测定乳制品中维生素D2和D3的方法。样品经皂化后,用石油醚提取,提取液经无水硫酸钠干燥,在氮气保护下旋转蒸发浓缩至10 m L以下,氮气吹干,用10 m L甲醇溶解后,经ACQUITY UPLC BEH C18色谱柱(1.7μm,2.1 mm×100 mm)分离,甲醇-水(95∶5)洗脱,多反应监测模式测定。维生素D2和D3在0.01~0.2 mg/L范围内呈良好的线性关系,相关系数(r2)分别为0.998 7和0.999 1,方法回收率为83.0%~99.4%,相对标准偏差(RSD)为2.0%~8.3%。     

Die quantitative chemische Bestimmung von Vitamin D

Zusammenfassung Es werden die Bedingungen zur photometrischen Bestimmung von Vitamin D mit Antimontrichlorid und Guajakol festgelegt. Die von der Vitamin D-Konzentration abhängige, beständige Grünfärbung wird durch Sterine nicht gestört, es sei denn, daß sie in 100fachem Überschuß vorhanden sind. Fette und deren Spaltprodukte stören durch eine gelbbraune Färbung, wodurch eine Verseifung natürlicher Fette notwendig wird.Die Absorptionskurven von Vitamin D₂ und D₃ zeigen völlige Übereinstimmung. Der Vitamin D₂-Gehalt wird unter dem Einfluß von Licht und Luft vermindert, wobei sich der Luftsauerstoff ungünstiger auswirkt als Licht. Kurzzeitiges Erhitzen auf 80–100° C schädigt das Vitamin D₂ nicht, eine längere Einwirkung höherer Temperaturen bedingt einen Abfall, der in einer Stickstoff-Atmosphäre geringer ist als unter SauerstoffAtmosphäre.Durch U.V.-Bestrahlung wird das Vitamin D₂ ebenso wie durch Sonnenlicht geschädigt, wobei die Verminderung durch 3stündige Sonnenbestrahlung etwa derjenigen einer 3 Minuten langen U.V.-Bestrahlung entspricht. Der Einfluß von Suprasterin und Toxisterin auf die Vitamin D-Reaktion ist nur gering, was für die Vitamin D-Bestimmung in bestrahlten Hefen von Bedeutung ist.     

Die quantitative chemische Bestimmung von Vitamin D

Zusammenfassung Die zur Vitamin D₂-Bestimmung bekannten spezifischen Farbreaktionen nachHalden und H.Brockmann werden durch die Unbeständigkeit des erhaltenen Farbtones und dieser durch Fettbegleitsubstanzen empfindlich gestört. Es gelingt, eine für Vitamin D spezifische, im Farbton beständige Reaktion bei Verwendung einer 20%igen Antimontrichloridund 5%igen Guajakol-Lösung in Chloroform. Die Empfindlichkeit der Reaktion ist 1200000. Es können quantitativ 15 in 2,8 ml Chloroform nachgewiesen werden bei tunlichster Einhaltung der beschriebenen Versuchsbedingungen.Der Einfluß der Sterine auf die Reaktion ist sehr gering, doch werden die Empfindlichkeit und die Spezifität dann vermindert, wenn sehr große Mengen dieser Begleitstoffe vorhanden sind. Mit Hilfe der Adsorption an frisch behandeltes, bei 120 erhitztes Aluminiumoxyd können störende Begleitstoffe abgetrennt werden. Das Vitamin D₂ wird dabei in einer scharf umrissenen Zone festgehalten, die im UV.-Licht weiß aufleuchtet.Die vorliegende Methode ist geeignet zur mengenmäßigen Bestimmung von Vitamin D in tierischen und pflanzlichen Fetten, in Milch und Milcherzeugnissen, in Kindernährmitteln, bestrahlten Hefen und pharmazeutischen Präparaten. Um die hier auftretenden, störenden Begleitstoffe auszuschalten, werden die Präparate nach der Extraktion des Vitamins D verseift, und der unverseifbare Anteil wird an Aluminiumoxyd adsorbiert. Dabei wird das Vitamin D bei Einhaltung der Arbeitsvorschrift immer in einer charakteristischen schmalen Zone festgehalten, die im Tageslicht gelb bis rosafarben erscheint. Durch die Anwesenheit von Vitamin A, Provitamin A und anderen. Carotinoiden kann die Reaktion gestört werden, so daß auch hier eine chromatographische Auftrennung erforderlich ist, die sich aber leicht durchführen läßt.     

Chemische Vitamin D3-Bestimmung in Lebertran

The different aspects of Vitamin D₃ determination and the data reported in the literature are discussed. The spectrophotometric determination of Vitamin D₃ in cod-liver oil is carried out after the alkaline saponification, extraction of unsaponified parts, precipitation of accompanying sterols and the column- and thin-layer chromatographic purification and separation of vitamin D₃ on 40 cm plates from other vitamins. The dyestuff α-naphtholbenzein is suited well as standard substance for the better location and identification of vitamin D₃ zone on the thin-layer plate. The results obtained from the chemical method were checked through the simultaneous biological determination.     

Sun Exposure and Vitamin D Status as Northeast Asian Migrants Become Acculturated to Life in Australia

Vitamin D deficiency is more common in Northeast‐Asian immigrants to western countries than in the local population; prevalence equalizes as immigrants adopt the host country's culture. In a community‐based study of 100 Northeast‐Asian immigrants in Canberra, Australia, we examined predictors of vitamin D status, its association with indicators of acculturation (English language use; time since migration) and mediators of that association. Participants completed a sun and physical activity diary and wore an electronic ultraviolet radiation (UVR) dosimeter for 7 days. Skin colour was measured by reflectance spectrophotometry. Serum concentrations of 25‐hydroxyvitamin D (25(OH)D) and cardio‐metabolic biomarkers were measured on fasting blood. In a multiple linear regression model, predictors for 25(OH)D concentration were season of blood collection, vitamin D supplementation, UVR exposure, body mass index, physical activity and having private health insurance (R² = 0.57). Greater acculturation was associated with lower risk of vitamin D deficiency (de‐seasonalized 25(OH)D level <50 nmol L^?1) (Adjusted Odds Ratio (AOR): 0.22 [95%CI 0.04–0.96]); this association was statistically mediated by physical activity and time outdoors. Vitamin D deficiency was associated with higher total cholesterol levels (>5.0 mmol L^?1) (AOR: 7.48 [95%CI 1.51–37.0]). Targeted public health approaches are required to manage the high prevalence of vitamin D deficiency in migrants retaining a traditional lifestyle.     

Vitamin D(2) modulates melittin-membrane interactions

In the present work, mutual interaction of melittin, a pore forming hemolytic toxin from bee venom, and vitamin D(2), an antioxidant steroid, with dipalmitoyl phosphatidylcholine (DPPC) multilamellar liposomes has been investigated. Turbidity and Fourier transform infrared (FTIR) spectroscopic measurements, in combination with thermodynamic calculations, were used to monitor the modulating effect of vitamin D(2) on a melittin-DPPC membrane system. The results indicate that melittin on its own decreases the main phase transition to lower temperatures and also dramatically decreases the stability of the membrane. It has an overall disordering effect on the phospholipid membrane structures. Inclusion of vitamin D(2) at low concentrations (3, 6 mol%) into melittin containing DPPC liposomes slightly shifts the main phase transition to lower temperatures. High concentration of vitamin D(2) (9 mol%) has a more dramatic effect in shifting the main phase transition to lower temperature. It also causes a significant broadening in the phase transition curve. The present study also demonstrates that, with the addition of vitamin D(2) into melittin-DPPC system, absorbance value in turbidity study and the frequency of the CH(2) stretching band in FTIR study changes in a manner that are consistent with a reduction in the membrane perturbing effect of melittin on DPPC liposomes. Vitamin D(2) diminishes the disordering effect of melittin on DPPC lipids and produces a more ordered membrane system. These results were confirmed with thermodynamic calculations.     

Beobachtungen bei der spektrophotometrischen Bestimmung von Vitamin D

Ohne Zusammenfassung     

Vitamin D receptor gene polymorphisms in breast cancer

Breast cancer is the leading cause of cancer death among women around the world and its incidence is annually increasing. The vitamin D receptor (VDR) gene is a member of the nuclear receptor superfamily, which is expressed in breast tissue and known to modulate the rate of cell proliferation. Association between the VDR gene polymorphisms and cancer development has been suggested by several studies. However, the relationship between VDR polymorphisms and breast cancer is controversial and has not been confirmed by all studies. The purpose of this study was to investigate the genotype frequencies and association of the VDR Bsm I and Taq I polymorphisms with breast cancer in Turkish patients. In this study, 78 patients with breast cancer and 27 healthy individuals were enrolled. The prevalence of the VDR Taq I and Bsm I alleles and the genotype frequencies in patients with breast cancer was similar to that in the normal population. Our data indicate that no significant differences exist between the patients and control subjects.