Pyridoxal Phosphate Concentrations Research Articles

Bmo-miR-6498-5p suppresses Bombyx mori nucleopolyhedrovirus infection by down-regulating BmPLPP2 to modulate pyridoxal phosphate content in B. mori.

The RNA interference pathway mediated by microRNAs (miRNAs) is one of the methods to defend against viruses in insects. Recent studies showed that miRNAs participate in viral infection by binding to target genes to regulate their expression. Here, we found that the Bombyx mori miRNA, miR-6498-5p was down-regulated, whereas its predicted target gene pyridoxal phosphate phosphatase PHOSPHO2 (BmPLPP2) was up-regulated upon Bombyx mori nucleopolyhedrovirus (BmNPV) infection. Both in vivo and in vitro experiments showed that miR-6498-5p targets BmPLPP2 and suppresses its expression. Furthermore, we found miR-6498-5p inhibits BmNPV genomic DNA (gDNA) replication, whereas BmPLPP2 promotes BmNPV gDNA replication. As a pyridoxal phosphate (PLP) phosphatase (PLPP), the overexpression of BmPLPP2 results in a reduction of PLP content, whereas the knockdown of BmPLPP2 leads to an increase in PLP content. In addition, exogenous PLP suppresses the replication of BmNPV gDNA; in contrast, the PLP inhibitor 4-deoxypyridoxine facilitates BmNPV gDNA replication. Taken together, we concluded that miR-6498-5p has a potential anti-BmNPV role by down-regulating BmPLPP2 to modulate PLP content, but BmNPV induces miR-6498-5p down-regulation to promote its proliferation. Our findings provide valuable insights into the role of host miRNA in B. mori-BmNPV interaction. Furthermore, the identification of the antiviral molecule PLP offers a novel perspective on strategies for preventing and managing viral infection in sericulture.

Vitamin B6: a scoping review for Nordic Nutrition Recommendations 2023.

Pyridoxal 5´-phosphate (PLP) is the main form of vitamin B6 in animal tissue and functions as a coenzyme for more than 160 different enzymatic reactions in the metabolism of amino acids, carbohydrates, lipids, and neurotransmitters. Estimated dietary intake of vitamin B6 and plasma PLP values differ a lot between studies, something which may be due to variable use of supplements, variations in dietary assessment and analytical methods. These factors make it difficult to achieve precise data for setting a correct recommended intake of vitamin B6. In addition, a plasma PLP concentration of 30 nmol/L is considered to be sufficient and the current recommendations for vitamin B6 intake is based on this concept. However, the metabolic marker for vitamin B6 status, HK ratio (HKr), starts to increase already when plasma PLP falls below 100 nmol/L and increases more steeply below 50 nmol/L, indicating biochemical deficiency. Consequently, a plasma PLP concentration of 30 nmol/L, may be too low as a marker for an adequate vitamin B6 status.

Optimization of Gamma-Aminobutyric Acid Production by Lactiplantibacillus plantarum FRT7 from Chinese Paocai.

Gamma-aminobutyric acid (GABA) is a widely available non-protein amino acid whose physiological importance goes beyond its role as an inhibitory neurotransmitter in mammals. The GABA synthesis ability of ten strains of Lactiplantibacillus plantarum was screened. They produced GABA ranging from 48.19 ± 3.44 to 100.75 ± 1.63 mg/L at 24 h-cultivation. Among them, Lp. plantarum FRT7 showed the highest GABA production. Therefore, FRT7 was chosen for GABA yield optimization. A one-factor-at-a-time strategy analysis of the GABA yield of FRT7 was performed, including the culture temperature, incubation time, inoculum volume, initial pH, the initial amount of monosodium glutamate (MSG), and pyridoxal 5'-phosphate (PLP) concentration, based on which the response surface methodology (RSM) was performed. After being cultured in an MRS culture medium supplemented with 3% MSG and 2 mmol/L of PLP at 40 °C with an initial pH of 7.0 for 48 h, the GABA reached a maximum yield of 1158.6 ± 21.22 mg/L. The results showed the experimental value of the GABA yield was in good agreement with the predicted values. Furthermore, the results from the RSM also indicated that the initial MSG addition, PLP concentration, and incubation time were significant variables. These results suggest that Lp. plantarum FRT7 has the potential to be a health-beneficial probiotic with commercial capabilities.

Connective Tissue Integrity is Lost in Vitamin B-6—Deficient Chicks

The objective of the present investigation was to characterize further the connective tissue disorder produced by pyridoxine (vitamin B-6) deficiency, as previously evidenced by electron microscopy. Following the second post-natal week, fast growing male chicks were deprived of pyridoxine for a 1-mo period. Six weeks post-natally, blood concentrations in the experimental deficiency group had declined to deficiency levels as registered by low concentrations of pyridoxal phosphate (coenzyme form) in erythrocytes, but did not reach levels associated with neurological symptoms. Light microscopic study showed abnormalities in the extracellular matrix of the connective tissues. Collagen cross-links and the aldehyde contents were not significantly lower in cartilage and tendon collagens of vitamin B-6—deficient animals than in age-matched controls; also, their proteoglycan degrading protease and collagenase activities measured in articular cartilages were not greater. Thus, proteolysis was an unlikely alternative mechanism to account for the loss of connective tissue integrity. These results point to the need for further investigation into adhesive properties of collagen associated proteoglycans or other proteins in vitamin B-6—deficient connective tissue.

Circulating pyridoxal 5′-phosphate in serum and whole blood: implications for assessment of vitamin B6 status

Abstract Objectives Concentrations of pyridoxal 5′-phosphate (PLP) in serum and whole blood are routinely measured. The suitability of these markers in capturing vitamin B6 insufficiency is not well studied. Methods In 212 subjects, concentrations of PLP and thiamine pyrophosphate (TPP) were simultaneously measured in EDTA-whole blood using Chromsystems® (52052) method on HPLC devices. The whole blood PLP concentrations were compared to serum PLP concentrations measured using reagents from Immundiagnostik® (KC 2100). The whole blood TPP concentrations measured with the Chromsystems® (52052) were compared to those measured by the Chromsystems® (35000) method. Concentrations of homocysteine (tHcy) and cystathionine (Cys) were measured and used to judge the PLP methods. Results Serum PLP concentrations were on average 41% lower than whole blood PLP [mean (SD)=55.4 (83.0) vs. 131 (217) nmol/L]. Serum and whole blood PLP showed a strong correlation [Pearson correlation coefficient=0.724, p<0.001, n=204]. Eighty-five samples showed discrepant results for PLP status (serum PLP ≤30 nmol/L, but whole blood PLP >51 nmol/L) while 102 samples showed coherent results (reference group). The discrepancy group showed higher odds ratio for elevated tHcy >12.0 μmol/L compared to the reference group [OR (95% confidence intervals, CI)=2.1 (1.2–4.0)]. The OR (95% CI) of elevated Cys >300 nmol/L was 1.9 (1.0–3.5) in the discrepancy group compared to the reference group. TPP concentrations were 6% lower when using the Chromsystems®, 52052 compared to levels measured with Chromsystems®, 35000. Conclusions Serum and whole blood PLP concentrations disagree in a substantial number of samples. Serum PLP was better in reflecting elevated tHcy and Cys compared to whole blood PLP. Whole blood PLP underestimates the prevalence of vitamin B6 insufficiency. Methods of measuring TPP concentrations in whole blood were exchangeable.

Vitamin B-6 and riboflavin, their metabolic interaction, and relationship with MTHFR genotype in adults aged 18–102 years

The generation of the active form of vitamin B-6, pyridoxal 5'-phosphate (PLP), in tissues is dependent upon riboflavin as flavin mononucleotide, but whether this interaction is important for maintaining vitamin B-6 status is unclear. To investigate vitamin B-6 and riboflavin status, their metabolic interaction, and relationship with methylenetetrahydrofolate reductase (MTHFR) genotype in adulthood. Data from 5612 adults aged 18-102 y were drawn from the Irish National Adult Nutrition Survey (NANS; population-based sample) and the Trinity-Ulster Department of Agriculture (TUDA) and Genovit cohorts (volunteer samples). Plasma PLP and erythrocyte glutathione reductase activation coefficient (EGRac), as a functional indicator of riboflavin, were determined. Older (≥65 y) compared with younger (<65 y) adults had significantly lower PLP concentrations (P<0.001). A stepwise decrease in plasma PLP was observed across riboflavin categories, from optimal (EGRac ≤1.26), to suboptimal (EGRac: 1.27-1.39), to deficient (EGRac ≥1.40) status, an effect most pronounced in older adults (mean±SEM: 76.4±0.9 vs 65.0±1.1 vs 55.4±1.2nmol/L; P<0.001). In individuals with the variant MTHFR 677TT genotype combined with riboflavin deficiency, compared with non-TT (CC/CT) genotype participants with sufficient riboflavin, we observed PLP concentrations of 52.1±2.9 compared with 76.8±0.7nmol/L (P<0.001). In participants with available dietary data (i.e., NANS cohort, n = 936), PLP was associated with vitamin B-6 intake (nonstandardized regression coefficient β: 2.49; 95% CI 1.75, 3.24; P<0.001), supplement use (β: 81.72; 95% CI: 66.01, 97.43; P<0.001), fortified food (β: 12.49; 95% CI: 2.08, 22.91; P=0.019), and EGRac (β: -65.81; 95% CI: -99.08, -32.54; P<0.001), along with BMI (β: -1.81; 95% CI: -3.31, -0.30; P=0.019). These results are consistent with the known metabolic dependency of PLP on flavin mononucleotide (FMN) and suggest that riboflavin may be the limiting nutrient for maintaining vitamin B-6 status, particularly in individuals with the MTHFR 677TT genotype. Randomized trials are necessary to investigate the PLP response to riboflavin intervention within the dietary range. The TUDA study and the NANS are registered at www.ClinicalTrials.gov as NCT02664584 (27 January 2016) and NCT03374748 (15 December 2017), respectively.Clinical Trial Registry details: Trinity-Ulster-Department of Agriculture (TUDA) study, ClinicalTrials.gov no. NCT02664584 (January 27th 2016); National Adult Nutrition Survey (NANS), ClinicalTrials.gov no. NCT03374748 (December 15th 2017).

Pyridoxal 5′-phosphate alleviates prenatal pyridaben exposure-induced anxiety-like behaviors in offspring

Pyridaben (PY) is a widely used organochlorine acaricide, which can be detected in the peripheral blood of pregnant women. Available evidence suggests that PY has reproductive toxicity. However, it remains uncertain whether prenatal PY exposure impacts neurobehavioral development in offspring. Here, we administered PY to pregnant mice at a dose of 0.5 and 5 mg kg−1 day−1 via gavage and observed anxiety-like behaviors in PY offspring aged five weeks. We then integrated the metabolome and transcriptome of the offspring's brain to explore the underlying mechanism. Metabolome data indicated that the vitamin B6 metabolism pathway was significantly affected, and the pyridoxal 5′-phosphate (PLP) concentration and the active form of vitamin B6 was significantly reduced. Moreover, the transcriptome data showed that both PLP generation-related Pdxk and anxiety-related Gad1 were significantly down-regulated. Meanwhile, there was a decreasing trend in the concentration of GABA in the hippocampal DG region. Next, we supplemented PLP at a dose of 20 mg kg−1 day−1 to the PY offspring via intraperitoneal injection at three weeks. We found up-regulated expression of Pdxk and Gad1 and restored anxiety-like behaviors. This study suggests that prenatal exposure to PY can disrupt vitamin B6 metabolism, reduce the concentration of PLP, down-regulate the expression levels of Pdxk and Gad1, inhibit the production of GABA, and ultimately lead to anxiety-like behaviors in offspring.

Anti-cancer activity of pyridoxal phosphate and metformin combination in human pancreatic cancer cells.

Background: Pancreatic cancer is the foremost cause of cancer-related deaths in many developed countries with a poor prognosis. With advanced disease conditions chemotherapy, surgery followed by radiation is the regimen to prolong the survival. But a complete cure is questionable. Metformin is the first-line drug used for the treatment of type 2 diabetes in the world. Aim: The study aims to assess the anti-cancer activity of metformin with the combination of micronutrient pyridoxal phosphate (PLP) in the human pancreatic cancer cell line (PANC-1). Methods: Panc1 cells were maintained in vitro cell culture conditions. The IC50 concentrations of metformin and PLP were estimated and selected by using MTT assay. Morphological changes upon treatments were observed under microscope. Distribution of cells pattern was observed with propidium iodide dye in cell cycle assay. Different phases of cell distribution were studied with apoptosis assay. Results: More morphological changes were observed with PLP followed metformin. MTT assay revelled the IC50 concentrations of metformin and PLP were 20.95 ± 0.98 mM and 5.70 ± 0.07 mM. The cell cycle assay revealed that the percentage of cells was arrested in different phases with the treatments. Apoptosis assay revelled metformin increased necrosis population to 9.9%, whereas PLP has enhanced to 14.2% apoptosis. Tumour suppressor protein p53 levels had increased to 24.8% with PLP and 3.5% with metformin. Conclusion: In conclusion, PLP has significantly induced cell cycle arrest, apoptosis and enhanced p53 protein expression but a combination of PLP with metformin drug has not synergised anti-cancer activity in human PANC1 cells.

ODP629 A Case of Juvenile Onset Hypophosphatasia Diagnosed In An Elderly Patient With Recurrent Fractures.

Abstract Background Hypophosphatasia (HPP) is a rare genetic disorder characterized by defective bone mineralization. Here we report a case of juvenile onset HPP in an elderly man. CASE A 77-year-old man presented for management of osteoporosis. He complained of joint pains and trouble walking. He had recurrent non-traumatic fractures since his teenage years and he and his sister were diagnosed with childhood rickets. He sustained fractures of both forearms, right ankle, right hip and left femoral neck, and had undergone right hip replacement and left femoral neck internal fixation. In his 20's, following a MVA he had several tooth extractions and eventually required dentures. He was misdiagnosed with osteogenesis imperfecta, vitamin D deficient osteomalacia and pseudogout, and had been treated with cholecalciferol and alendronate in the past. On exam, we noted a waddling gait, short stature and bowing of his knees. Labs revealed normal vitamin D 25-OH 48 ng/mL (30-100), and PTH 18 pg/mL (14-64), borderline corrected calcium 10.5 mg/dL (8.4-10.6) and elevated phosphorous 4.4 mg/dL (2.2-4.3). ALP was notably low 30 U/L (40-150) and had ranged between 15-46 U/L since 2009. These findings caught our attention and we ordered Vitamin B6 levels which were elevated &amp;gt;250. 0 ng/mL (2.1-21.7). Genetic testing identified two ALPL gene variants, a rare C.340G&amp;gt;A variant and a c.571G&amp;gt;A variant which has been found to be causative of HPP. His DXA scan showed normal L-spine (T-score 3.3) and significantly decreased BMD of the proximal 1/3 of the left forearm (T-score -4.4). Hip and femur were not assessed due to presence of hardware. He is scheduled to start treatment with Asfotase alfa. Conclusion HPP is caused by ALPL gene mutations, which lead to loss of function of the enzyme tissue nonspecific alkaline phosphatase (TSNALP). Clinical manifestations such as seizures, recurrent fractures and premature dental loss are observed. Pseudogout may occur due to intraarticular calcium pyrophosphate deposition, as in our patient. Characteristic lab findings are elevated metabolites of TNSALP, including urine inorganic pyrophosphate (PPi) and serum pyridoxal 5'phosphate (PLP) (biologically active metabolite of vitamin B-6). A persistently low ALP is most suggestive and may be a clue for early referral. Genetic testing is confirmatory, but novel mutations may be missed. Delayed diagnosis in our patient led to increased morbidity, potentially avoidable surgeries and inappropriate treatment with bisphosphonate which are contraindicated as they may increase risk for atypical fractures. Asfotase alfa is a TNSALP enzyme replacement therapy designed to address the underlying cause of HPP and studies show improvement in bone mineralization, fracture healing, decreased concentration of PLP and PPi, and improved physical function and quality of life. Cost and availability remain a barrier to many patients. Presentation: No date and time listed

Preventing Vitamin B6-Related Neurotoxicity.

Vitamin B6 is essential for life and plays a critical role in many biochemical and physiological processes in the human body. The term B6 collectively refers to 6 water-soluble vitamers, and only the pyridoxal 5'-phosphate (PLP) serves as the biologically active form. A plasma PLP concentration above 30 nmol/L (7.4 μg/L) is indicative of an adequate vitamin B6 status for all age and sex groups. The currently recommended daily allowance of B6 (1.5-2 mg/d) from dietary sources frequently results in inadequate B6 status (<20 nmol/L or 5 μg/L) in many elderly patients and patients with comorbid conditions. PLP-based supplements are preferred and should be administered weekly in low doses (50-100 mg) to maintain a stable serum PLP level between 30 and 60 nmol/L or 7.4 and 15 μg/L. It is challenging for physicians to prescribe a safe dose of B6 supplements because of the narrow therapeutic index. The association between elevated levels of pyridoxine and neuropathy is not well established. PLP-based supplements are shown to be least neurotoxic, but further clinical trials are needed to establish the long-term safety in high doses. PubMed search of randomized control trials and meta-analyses. Plasma B6 levels should be ordered as a part of workup of any unexplained anemia before labeling as "anemia of chronic disease." B6 supplementation is also crucial in the management of chronic Mg deficiency resistant to therapy. When B6 is administered daily in supraphysiologic doses, there is a potential for the development of neurotoxicity (typically at levels >100 nmol/L or 25 μg/L). PLP-based supplements are preferred over pyridoxine supplements because of minimal neurotoxicity observed in neuronal cell viability tests. Since B6 metabolites have a long half-life, weekly administration is preferred over daily use to prevent toxicity.

Association of Pyridoxal 5'-Phosphate with Sleep-Related Problems in a General Population.

The evidence on the relationship of pyridoxal 5′-phosphate (PLP) with sleep-related problems is limited and controversial. Notably, there is a lack of studies on the general population and studies of the dose–response relationship. Therefore, we conducted a cross-sectional study to examine the associations between serum PLP concentration and sleep-related problems (sleep quality and sleep duration) in adults, using the data of the National Health and Nutrition Examination Survey 2005–2010. High-performance liquid chromatography (HPLC) was used to test PLP in blood samples. Sleep quality and sleep duration were based on self-reported data, with sleep quality categorized as sleep disorder, trouble falling asleep, waking up during the night, and daytime sleepiness. The primary analyses utilized logistic regression models and restricted cubic spline. Compared with the first quartile (Q1), the odds ratios (ORs) and 95% confidence intervals (CIs) of daytime sleepiness for the Q2 and Q3 of serum PLP concentrations were 0.76 (0.59–0.99) and 0.78 (0.62–0.98), respectively. The relationship was only significant for males. Furthermore, a non-linear dose–response relationship was observed between serum PLP concentration and the risk of daytime sleepiness. Compared with the normal sleep duration group, serum PLP concentrations were negatively associated with the risks of very short, short, and long sleep duration, with relative risk ratios (RRRs) of 0.58 (0.43–0.81) (Q4), 0.71 (0.61–0.83) (Q4) and 0.62 (0.34–0.94) (Q3), respectively. The average serum PLP concentrations were higher in people with normal sleep duration, suggesting a non-linear dose–response relationship. Our study indicated that serum PLP concentrations were negatively associated with daytime sleepiness, and this association may only exist in males. Moreover, it was also inversely related to abnormal sleep duration (very short, short, long) compared to normal sleep duration.

Higher vitamin B6 status is associated with improved survival among patients with stage I–III colorectal cancer

Folate-mediated 1-carbon metabolism requires several nutrients, including vitamin B6. Circulating biomarker concentrations indicating high vitamin B6 status are associated with a reduced risk of colorectal cancer (CRC). However, little is known about the effect of B6 status in relation to clinical outcomes in CRC patients. We investigated survival outcomes in relation to vitamin B6 status in prospectively followed CRC patients. A total of 2031 patients with stage I-III CRC participated in 6 prospective patient cohorts in the international FOCUS (folate-dependent 1-carbon metabolism in colorectal cancer recurrence and survival) Consortium. Preoperative blood samples were used to measure vitamin B6 status by the direct marker pyridoxal 5'-phosphate (PLP), as well as the functional marker HK-ratio (HKr)[3'-hydroxykynurenine: (kynurenic acid+xanthurenic acid+3'-hydroxy anthranilic acid+anthranilic acid)]. Using Cox proportional hazards regression, we examined associations of vitamin B6 status with overall survival (OS), disease-free survival (DFS), and risk of recurrence, adjusted for patient age, sex, circulating creatinine concentrations, tumor site, stage, and cohort. After a median follow-up of 3.2 y for OS, higher preoperative vitamin B6 status as assessed by PLP and the functional marker HKr was associated with 16-32% higher all-cause and disease-free survival, although there was no significant association with disease recurrence (doubling in PLP concentration: HROS, 0.68; 95% CI: 0.59, 0.79; HRDFS, 0.84; 95% CI: 0.75, 0.94; HRRecurrence, 0.96; 95% CI: 0.84, 1.09; HKr: HROS, 2.04; 95% CI: 1.67, 2.49; HRDFS, 1.56; 95% CI: 1.31, 1.85; HRRecurrence, 1.21; 95% CI: 0.96,1. 52). The association of PLP with improved OS was consistent across colorectal tumor site (right-sided colon: HROS, 0.75; 95% CI: 0.59, 0.96; left-sided colon: HROS, 0.71; 95% CI: 0.55, 0.92; rectosigmoid junction and rectum: HROS, 0.61; 95% CI: 0.47, 0.78). Higher preoperative vitamin B6 status is associated with improved OS among stage I-III CRC patients.

Associations of Serum Vitamin B6 Status and Catabolism With All-Cause Mortality in Patients With T2DM.

Context There is little evidence regarding the association between serum vitamin B6 status and catabolism and all-cause mortality in patients with type-2 diabetes mellitus (T2DM).Objective We aimed to ascertain if the serum level of vitamin B6 and catabolism, including pyridoxal 5′-phosphate (PLP) and 4-pyridoxic acid (4-PA), were associated with risk of all-cause mortality in T2DM patients.MethodsThis prospective cohort study involved 2574 patients with T2DM who participated in the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2010. The serum concentrations of PLP and 4-PA were used to assess the serum level of vitamin B6. Mortality status was determined by routine follow-up using the National Death Index through December 31, 2015.ResultsOver a median follow-up of 85 months, there were 588 deaths. The fully adjusted Cox model indicated that the highest serum PLP concentrations (> 63.6 nmol/L) were associated with a decrease in all-cause mortality (hazard ratio [HR], 0.74; 95% CI, 0.55-0.99, P trend = .035). The risk for all-cause mortality was 59% higher for participants with the highest quartile of 4-PA level compared with the lowest quartile (HR, 1.62; 95% CI, 1.12-2.35; P trend = .003). The sensitivity and specificity of the combination of PLP and 4-PA levels for the prediction of all-cause mortality were 59.5% and 60.9%, respectively (area under the receiver operating characteristic curve = 0.632). The Kaplan-Meier method was used to estimate overall survival for patients based on different combinations of PLP level and 4-PA level. Patients with PLP less than 24.3 nmol/L and 4-PA greater than or equal to 25.4 nmol/L had the worst outcomes (log-rank P < .001).ConclusionOverall, our data suggest that a low serum level of PLP and high serum level of 4-PA, which represent the serum level of vitamin B6, increases the risk of all-cause mortality significantly in patients with T2DM.

Application of the deep learning algorithm in nutrition research – using serum pyridoxal 5′-phosphate as an example

BackgroundMultivariable linear regression (MLR) models were previously used to predict serum pyridoxal 5′-phosphate (PLP) concentration, the active coenzyme form of vitamin B6, but with low predictability. We developed a deep learning algorithm (DLA) to predict serum PLP based on dietary intake, dietary supplements, and other potential predictors.MethodsThis cross-sectional analysis included 3778 participants aged ≥20 years in the National Health and Nutrition Examination Survey (NHANES) 2007-2010, with completed information on studied variables. Dietary intake and supplement use were assessed with two 24-hour dietary recalls. We included potential predictors for serum PLP concentration in the models, including dietary intake and supplement use, sociodemographic variables (age, sex, race-ethnicity, income, and education), lifestyle variables (smoking status and physical activity level), body mass index, medication use, blood pressure, blood lipids, glucose, and C-reactive protein. We used a 4-hidden-layer deep neural network to predict PLP concentration, with 3401 (90%) participants for training and 377 (10%) participants for test using random sampling. We obtained outputs after sending the features of the training set and conducting forward propagation. We then constructed a loss function based on the distances between outputs and labels and optimized it to find good parameters to fit the training set. We also developed a prediction model using MLR.ResultsAfter training for 105 steps with the Adam optimization method, the highest R2 was 0.47 for the DLA and 0.18 for the MLR model in the test dataset. Similar results were observed in the sensitivity analyses after we excluded supplement-users or included only variables identified by stepwise regression models.ConclusionsDLA achieved superior performance in predicting serum PLP concentration, relative to the traditional MLR model, using a nationally representative sample. As preliminary data analyses, the current study shed light on the use of DLA to understand a modifiable lifestyle factor.

Colorimetric detection of alkaline phosphatase activity based on pyridoxal phosphate-induced chromatic switch of polydiacetylene nano-liposomes.

Acolorimetric assay based on polydiacetylenes (PDA) nano-liposomes is reported for facile and sensitive detection of alkaline phosphatase (ALP) activity. The critical basis of this method is that the interaction of pyridoxal phosphate (PLP) with nitrogenous group functionalized PDA nano-liposomes induces distinct blue-to-red color changes of PDA nano-liposomes. In the presence of ALP, as a nature substrate, PLP is enzymatically hydrolyzed to form pyridoxal, which cannot interact with PDA nano-liposomes. As a result, the concentration of PLP is reduced and the color change of PDA nano-liposomes is retarded, which isassociated with ALP level. Under optimal conditions, the proposed method showed good linear relationship with ALP activity in the range 10-200 U/L with a limit of detection of 2.8 U/L. The detection process could be vividly observed with the naked eye. Additional attempts by using the method for the evaluation of inhibitor efficiency were also achieved with satisfying results. The method was further challenged with real human serum samples, showing consistent results when compared with a commercial standard assay kit. Such simple and easy-to-use approach may provide a new alternative for clinical and biological detection of ALP.

Hypophosphatasia: Vitamin B6 status of affected children and adults.

Hypophosphatasia (HPP) is the heritable dento-osseous disease caused by loss-of-function mutation(s) of the gene ALPL that encodes the tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP). TNSALP is a cell-surface homodimeric phosphomonoester phosphohydrolase expressed in healthy people especially in the skeleton, liver, kidneys, and developing teeth. In HPP, diminished TNSALP activity leads to extracellular accumulation of its natural substrates including inorganic pyrophosphate (PPi), an inhibitor of mineralization, and pyridoxal 5'-phosphate (PLP), the principal circulating form of vitamin B6 (B6). Autosomal dominant and autosomal recessive inheritance involving >450 usually missense defects scattered throughout ALPL largely explains the remarkably broad-ranging severity of this inborn-error-of-metabolism. In 1985 when we identified elevated plasma PLP as a biochemical hallmark of HPP, all 14 investigated affected children and adults had markedly increased PLP levels. However, pyridoxal (PL), the dephosphorylated form of PLP that enters cells to cofactor many enzymatic reactions, was not low but often inexplicably elevated. Levels of pyridoxic acid (PA), the B6 degradation product quantified to assess B6 sufficiency, were unremarkable. Canonical signs or symptoms of B6 deficiency or toxicity were absent. B6-dependent seizures in infants with life-threatening HPP were later explained by their profound deficiency of TNSALP activity blocking PLP dephosphorylation to PL and diminishing gamma-aminobutyric acid synthesis in the brain. Now, there is speculation that altered B6 metabolism causes further clinical complications in HPP. Herein, we assessed the plasma PL and PA levels accompanying previously reported elevated plasma PLP concentrations in 150 children and adolescents with HPP. Their mean (SD) plasma PL level was nearly double the mean for our healthy pediatric controls: 66.7 (59.0) nM versus 37.1 (22.2) nM (P<0.0001), respectively. Their PA levels were broader than our pediatric control range, but their mean value was normal; 40.2 (25.1) nM versus 39.3 (9.9) nM (P=0.7793), respectively. In contrast, adults with HPP often had plasma PL and PA levels suggestive of dietary B6 insufficiency. We discuss why the B6 levels of our pediatric patients with HPP would not cause B6 toxicity or deficiency, whereas in affected adults dietary B6 insufficiency can develop.

Association of Serum Vitamin B6 with All-Cause and Cause-Specific Mortality in a Prospective Study

There is little evidence regarding the association between serum vitamin B6 concentration and subsequent mortality. We aimed to evaluate the association of serum vitamin B6 concentration with all-cause, cardiovascular disease (CVD), and cancer mortality in the general population using data from the National Health and Nutrition Examination Survey (NHANES). Our study examined 12,190 adults participating in NHANES from 2005 to 2010 in the United States. The mortality status was linked to National Death Index (NDI) records up to 31 December 2015. Pyridoxal 5′-phosphate (PLP) is the biologically active form of vitamin B6. Vitamin B6 status was defined as deficient (PLP < 20 nmol/L), insufficient (PLP ≥ 20.0 and <30.0 nmol/L), and sufficient (PLP ≥ 30.0 nmol/L). We established Cox proportional-hazards models to estimate the associations of categorized vitamin B6 concentration and log-transformed PLP concentration with all-cause and cause-specific mortality by calculating hazard ratios (HRs) and 95% confidence intervals (95%CIs). In our study, serum vitamin B6 was sufficient in 70.6% of participants, while 12.8% of the subjects were deficient in vitamin B6. During follow-up, a total of 1244 deaths were recorded, including 294 cancer deaths and 235 CVD deaths. After multivariate adjustment in Cox regression, participants with higher serum vitamin B6 had a 15% (HR = 0.85, 95%CI = 0.77, 0.93) reduced risk of all-cause mortality and a 19% (HR = 0.81, 95%CI = 0.68, 0.98) reduced risk for CVD mortality for each unit increment in natural log-transformed PLP. A higher log-transformed PLP was not significantly associated with a lower risk for cancer mortality. Compared with sufficient vitamin B6, deficient (HR = 1.37, 95%CI = 1.17, 1.60) and insufficient (HR = 1.19, 95%CI = 1.02, 1.38) vitamin B6 level were significantly associated with a higher risk for all-cause mortality. There was no significant association for cause-specific mortality. Participants with higher levels of vitamin B6 had a lower risk for all-cause mortality. These findings suggest that maintaining a sufficient level of serum vitamin B6 may lower the all-cause mortality risk in the general population.

Sequential detection of vitamin B6 cofactors and nitroaromatics by using albumin-stabilized fluorescent copper nanoclusters

The red-emitting bovine serum albumin (BSA) stabilized copper nanoclusters (BSA-CuNCs) was applied for the cascade detection of vitamin B6 cofactors and nitroaromatics. The fluorescence profile of BSA-CuNCs is perturbed with the addition of cofactors pyridoxal and pyridoxal 5′-phosphate (PLP). The fluorescence intensity at 640 nm of BSA-CuNCs is decreased with the concomitant appearance of a new emission band between 450 and 460 nm. The –CHO group of pyridoxal/PLP is expected to form an imine linkage with the free –NH2 group available with the functionalized BSA, which altered the conformation of BSA and the fluorescence profile of BSA-CuNCs. Importantly, the BSA-CuNCs showed selective fluorescence response towards pyridoxal at lower concentration among the other examined cofactors. Using BSA-CuNCs as a nanoprobe, the concentration of pyridoxal and PLP can be detected down to 66.3 nM and 1.08 μM, respectively. Subsequently, the pyridoxal and PLP conjugated BSA-CuNCs was applied for the fluorescent detection of nitroaromatics. The fluorescence of pyridoxal and PLP conjugated BSA-CuNCs was selectively quenched with the addition of picric acid and para-nitrophenol due to the energy and electron transfer processes.

Engineered production of pyridoxal 5′-phosphate in Escherichia coli BL21

Pyridoxal 5′-phosphate (PLP) is the coenzyme of more than 140 enzymes and is widely used in various fields. In this study, to enhance the production of PLP in Escherichia coli BL21, the recombinant strain E. coli BL21/pETDuet-1-pdxj-zwf-dxs was constructed. The concentration of PLP in this strain was 82.69 mg/L, which was increased by 1.38-fold as compared to that in E. coli BL21. Glucose, yeast extract, and pH had an obvious impact on the concentration of PLP, and their optimal levels were 34.89 g/L, 31.17 g/L, and 10.07, respectively. The concentration of PLP under the optimal condition reached 2.23 g/L. The time-course analysis showed that the highest concentration of PLP was 2.32 g/L in recombinant strain after the induction for 12 h by 0.1 mM IPTG in a 1 L shake flask, which was increased by 38.76-fold as compared to that in E. coli BL21. This study provides a good basis for the efficient production of PLP in E. coli BL21.

A comparison of complementary measures of vitamin B6 status, function, and metabolism in the European Prospective Investigation into Cancer and Nutrition (EPIC) study

ABSTRACTBackgroundVitamin B6 insufficiency has been linked to increased risk of cancer and other chronic diseases. The circulating concentration of pyridoxal 5′-phosphate (PLP) is a commonly used measure of vitamin B6 status. Ratios of substrates indicating PLP coenzymatic function and metabolism may be useful complementary measures to further explore the role of vitamin B6 in health.ObjectivesWe explored the sensitivity of 5 outcomes, namely PLP concentration, homocysteine:cysteine (Hcy:Cys), cystathionine:cysteine (Cysta:Cys), the 3´-hydroxykynurenine ratio (HKr), and the 4-pyridoxic acid ratio (PAr) to vitamin B6 intake as well as personal and lifestyle characteristics.MedthodsDietary intake and biomarker data were collected from participants from 3 nested case-control studies within the European Prospective Investigation into Cancer and Nutrition (EPIC). Bayesian regression models assessed the associations of the 5 biomarker outcomes with vitamin B6 intake and personal and lifestyle covariates. Analogous models examined the relations of Hcy:Cys, Cysta:Cys, and HKr with PLP.ResultsIn total, 4608 participants were included in the analyses. Vitamin B6 intake was most strongly associated with PLP, moderately associated with Hcy:Cys, Cysta:Cys, and HKr, and not associated with PAr (fold change in marker given a doubling of vitamin B6 intake: PLP 1.60 [95% credible interval (CrI): 1.50, 1.71]; Hcy:Cys 0.87 [95% CrI: 0.84, 0.90]; Cysta:Cys 0.89 [95% CrI: 0.84, 0.94]; HKr 0.88 [95% CrI: 0.85, 0.91]; PAr 1.00 [95% CrI: 0.95, 1.05]). PAr was most sensitive to age, and HKr was least sensitive to BMI and alcohol intake. Sex and menopause status were strongly associated with all 5 markers.ConclusionsWe found that 5 different markers, capturing different aspects of vitamin B6–related biological processes, varied in their associations with vitamin B6 intake and personal and lifestyle predictors.