OBJECTIVE: This study aimed to determine the binding of vitamin E isomers on transport proteins using in silico docking.
METHODS: Transport proteins were selected using AmiGo Gene Ontology tool based on the same molecular function annotation as αTTP. Protein structures were obtained from the Protein Data Bank. Ligands structures were obtained from ZINC database. In silico docking was performed using SwissDock.
RESULTS AND DISCUSSION: A total of 6 transport proteins were found: SEC14-like protein 2, glycolipid transfer protein (GLTP), pleckstrin homology domain-containing family A member 8, collagen type IV alpha-3-binding protein, ceramide-1-phosphate transfer protein and afamin. Compared with other transport proteins, αTTP had the highest affinities for all isomers except βT3. Binding order of vitamin E isomers toward αTTP was γT > βT > αT > δT > αT3 > γT3 > δT3 > βT3. GLTP had a higher affinity for tocotrienols than tocopherols. βT3 bound stronger to GLTP than αTTP.
CONCLUSION: αTTP remained as the most preferred transport protein for most of the isomers. The binding affinity of αT toward αTTP was not the highest than other isomers suggested that other intracellular trafficking mechanisms of these isomers may exist. GLTP may mediate the intracellular transport of tocotrienols, especially βT3. Improving the bioavailability of these isomers may enhance their beneficial effects to human.
DESIGN: Longitudinal study.
SETTING: UVB exposure (using polysulfone film badges) and skin colour and dietary vitamin D intake (by web-based questionnaire) were measured at each season in AB and during south-west (SWM) and north-east monsoons (NEM) in KL.
SUBJECTS: One hundred and fifteen Asians in KL and eighty-five Asians in AB aged 20-50 years.
RESULTS: Median summer UVB exposure of Asians in AB (0·25 SED/d) was higher than UVB exposure for the KL participants (SWM=0·20 SED/d, P=0·02; NEM= 0·14 SED/d, P<0·01). UVB exposure was the major source of vitamin D in KL year-round (60%) but only during summer in AB (59%). Median dietary vitamin D intake was higher in AB (3·50 µg/d (140 IU/d)), year-round, than in KL (SWM=2·05 µg/d (82 IU/d); NEM=1·83 µg/d (73 IU/d), P<0·01). Median total vitamin D (UVB plus diet) was higher in AB only during summer (8·45 µg/d (338 IU/d)) compared with KL (SWM=6·03 µg/d (241 IU/d), P=0·04; NEM=5·35 µg/d (214 IU/d), P<0·01), with a comparable intake across the full year (AB=5·75 µg/d (230 IU/d); KL=6·15 µg/d (246 IU/d), P=0·78).
CONCLUSIONS: UVB exposure among Asians in their home country is low. For Asians residing at the northerly latitude of Scotland, acquiring vitamin D needs from UVB exposure alone (except in summer) may be challenging due to low ambient UVB in AB (available only from April to October).
MATERIALS AND METHODS: We performed a cross-sectional study involving 70 patients with biopsy-proven immunoglobulin A nephropathy with a stable estimated glomerular filtration rate and urinary albuminuria. Their demographic profiles were documented, and blood samples were taken for serum 25-hydroxyvitamin D, highly sensitive C-reactive protein, urine albuminuria and other routine blood tests.
RESULTS: We found nine patients (12.9%) had sufficient 25- hydroxyvitamin D [25(OH)D] levels of more than 30ng/mL and the rest of the patients; 61 (87.1%) had serum 25(OH)D levels below 30 ng/ml. Amongst those with low vitamin D, 38 (62.3%) had serum 25(OH)D between 15-30 ng/mL (insufficient), and the remaining 23 (37.7%) had serum 25(OH)D below 15 ng/ml (deficient). Their mean level of serum 25(OH)D was 19.92 ± 9.04 ng/mL with a serum creatinine of 106.23 ± 38.56 μmol/L and mean estimated glomerular filtration rate (eGFR) at 68.11± 27.65 mL/min/1.73 m2. There was no association between urinary albuminuria, highly sensitive C-reactive protein, estimated glomerular filtration rate or systolic blood pressure with serum 25(OH)D level.
CONCLUSION: Low vitamin D (insufficiency and deficiency) are indeed prevalent in stable immunoglobulin A nephropathy patients. We found no correlation between the vitamin D levels with albuminuria, renal function and highly sensitive C-reactive.