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Quinones can accept two electrons and two protons, and are involved in electron transfer and proton transfer reactions in photosynthetic reaction centers. To date, the pK.sub.a of these quinones in aqueous solution have not been reported. We calculated the pK.sub.a of the initial protonation (Q.sup.·- to QH.sup.·) and the second protonation (QH.sup.- to QH.sub.2) of 1,4-quinones using a quantum chemical approach. The calculated energy differences of the protonation reactions Q.sup.·- to QH.sup.· and QH.sup.- to QH.sub.2 in the aqueous phase for nine 1,4-quinones were highly correlated with the experimentally measured pK.sub.a(Q.sup.·-/QH.sup.·) and pK.sub.a(QH.sup.-/QH.sub.2), respectively. In the present study, we report the pK.sub.a(Q.sup.·-/QH.sup.·) and pK.sub.a(QH.sup.-/QH.sub.2) of ubiquinone, menaquinone, phylloquinone, plastoquinone, and rhodoquinone in aqueous solution.

This study aims to investigate the reproducibility and relative validity of the Dutch food frequency questionnaire (FFQ), to estimate intake of dietary phylloquinone and menaquinones compared with 24-h dietary recalls (24HDRs) and plasma markers of vitamin K status. Intraclass correlations showed a good reproducibility, with correlations ranging from 0.65 to 0.83. The relative validity for phylloquinone intake compared with 24HDR was lower for women (r.sub.s=0.28) than men (r.sub.s=0.40). The relative validity, compared with 24HDR, for intake of short-chain menaquinones were ranging between 0.30 and 0.34. Long-chain menaquinones showed good relative validity (r.sub.s=0.60-0.69). Plasma phylloquinone concentrations were weakly correlated with phylloquinone intake (r.sub.s=0.16 (0.07-0.24). Plasma dpucMGP was negatively but weakly correlated with phylloquinone intake (r.sub.s=-0.09 (-0.18; -0.01)) and long-chain menaquinones (r.sub.s=-0.13 (-0.21; -0.04)), but not with short-chain menaquinones (r.sub.s=-0.04 (-0.13; 0.05)). The FFQ is reproducible to rank subjects for phylloquinone and menaquinone intake.The relative validity of our FFQ, compared with 24HDR, to estimate intake of phylloquinone and short-chain menaquinones was low, but the relative validity for long-chain menaquinones was good. The relative validity of our FFQ, compared with plasma phylloquinone and dpucMGP, was relatively low for both phylloquinone and menaquinone intake.

Phylloquinone (Phyllo) or vitamin K1 is mostly available in plant-based foods such as spinach and lettuce. Because Phyllo absorption in the human gut is low, foods with significantly high levels of Phyllo can aid in maintaining adequate vitamin K levels when consumed. We conducted two experiments, i.e., monochromatic and broadband, to understand the effects of light quality on enhancing Phyllo levels in lettuce. Both experiments used green romaine lettuce and a customized indoor growth system with light emitting diode (LED) lights. We measured fresh weight (FW), dry weight, leaf area, leaf number, and Phyllo levels in both experiments. Photosynthesis (A)- photon flux density ( PPFD ) response curves were measured in the second experiment. In the first experiment, plants were grown under six monochromatic light treatments viz., ultraviolet (UV 389 ), blue (B 450 ), green (G 521 ), red (R 632 ), hyper-red (R 662 ), and far-red (FR 733 ) during the entire growth period. Phyllo level was higher in UV 389 and not different among other treatments. Vegetative growth parameters trended in the order of R 632  > R 662 /G 521  > B 450  > UV 389  > FR 733 . These results suggested that UV 389 can increase Phyllo levels but its addition can have a negative effect on vegetative growth. In the second experiment, plants were grown under two treatments viz., UV 389 substituted in the broadband light (40% of total light) during the stationary growth stage (UV sub ) and control (broadband light without substitution). Results indicated that FW was lower by 24% but Phyllo level increased by approximately 175% in the UV sub treatment compared to control. These results suggest that UV 389 provided during the stationary growth phase can enhance Phyllo, however, further lowering the percentage of UV 389 may be required to minimize the negative effect on vegetative growth. Analysis of A- PPFD curves indicated lower operating photosynthesis (A OP ) and light use efficiency (LUE) in the UV sub compared to control. Analysis indicated that UV-A light provided during the stationary growth stage contributed little to A OP . This suggests that increased Phyllo levels from UV-A exposure did not enhance A but likely provided photoprotection by channeling excess excitation energy through alternate pathways.

Abstract Background Information regarding measurement and supplementation of vitamin K1 (vitK1) in dogs with chronic enteropathy (CE) is limited. Hypothesis/Objectives Compare vitK1 concentrations of healthy dogs to dogs with CE and determine if supplementation with vitK1 increases vitK1 concentrations compared to placebo. Animals Twenty client-owned dogs with CE and 20 healthy university-owned research colony dogs. Methods Prospective, randomized, placebo-controlled study. Dogs with CE were randomly assigned to receive placebo or vitk1 2.5 mg/kg PO q12h for 3 weeks. Vitamin K concentrations were measured pre- and post supplementation using liquid chromatography tandem mass spectrometry and compared to vitK1 concentrations in the healthy cohort. Results All healthy dogs had initial vitK1 median concentrations of 0.10 ng/mL (interquartile range [IQR], 0.05), which was similar to dogs that received either placebo (n = 5; 0.10 ng/mL; IQR, 0.05) or vitK1 (n = 7; 0.10 ng/mL; IQR, 0.05) before supplementation. Dogs with CE receiving vitK1 had increased vitK1 concentrations (12.5 ng/mL; IQR, 4.1) after 3 weeks of supplementation compared with baseline (0.10 ng/mL; p < 0.001), placebo group after 3 weeks (0.10 ng/mL; p < 0.0001) and healthy dogs (0.10 ng/mL; p < 0.004). Conclusions and Clinical Importance Oral supplementation with vitK1 increased vitK1 concentration in the serum of dogs with CE, but a clinical benefit from increased vitK1 concentrations was not identified. The absence of difference in vitK1 concentrations between healthy and CE dogs before supplementation requires additional investigation.

Quinones serve as redox active cofactors in bacterial photosynthetic reaction centers: photosystem I, photosystem II, cytochrome bc 1 , and cytochrome b 6 f . In particular, ubiquinone is ubiquitous in animals and most bacteria and plays a key role in several cellular processes, e.g., mitochondrial electron transport. Their experimentally measured redox potential values for one-electron reduction E m (Q/Q ·− ) were already reported in dimethylformamide (DMF) versus saturated calomel electrode but not in water versus normal hydrogen electrode (NHE). We calculated E m (Q/Q ·− ) of 1,4-quinones using a quantum chemical approach. The calculated energy differences of reduction of Q to Q ·− in DMF and water for 1,4-quinone derivatives correlated highly with the experimentally measured E m (Q/Q ·− ) in DMF and water, respectively. E m (Q/Q ·− ) were calculated to be −163 mV for ubiquinone, −260 mV for menaquinone and phylloquinone, and −154 mV for plastoquinone in water versus NHE.

OBJECTIVE: To investigate whether dietary phylloquinone and menaquinones intakes are related to risk of type 2 diabetes. RESEARCH DESIGN AND METHODS: We used data from a prospective cohort study in 38,094 Dutch men and women, aged 20-70 years. Dietary phylloquinone and menaquinones intakes were assessed using a validated food frequency questionnaire. Diabetes case patients were ascertained mainly via self-report and verified against medical records. RESULTS: During 10.3 years of follow-up, 918 incident cases of diabetes were documented. In a multivariate model adjusting for diabetes risk factors and dietary factors, phylloquinone intake tended to be associated (P = 0.08) with a reduced risk of type 2 diabetes with a hazard ratio (HR) of 0.81 (95% CI 0.66-0.99) for the highest versus the lowest quartile. For menaquinones intake, a linear, inverse association (P = 0.038) with risk of type 2 diabetes was observed with an HR of 0.93 (0.87-1.00) for each 10-μg increment in the multivariate model. CONCLUSIONS: This study shows that both phylloquinone and menaquinones intakes may be associated with a reduced risk of type 2 diabetes.

Lipid-soluble vitamins are essential micronutrients that play a vital role in processes such as growth, reproduction, immune regulation, antioxidant defense, anti-inflammatory response and cardiovascular health. This study aimed to evaluate the plasma levels of retinol, cholecalciferol, α-tocopherol and phylloquinone in dogs with dilated cardiomyopathy (DCM). Six dogs diagnosed with DCM and ten healthy control dogs were selected based on clinical, echocardiographic, electrocardiographic and radiographic examinations. Chromatographic analysis was performed to analyze the content of lipid-soluble vitamins. The mean plasma retinol levels were 0.0285 μg/mL and 0.0495 μg/mL in the DCM and control groups, respectively, and the mean cholecalciferol levels were 0.0739 μg/mL and 0.1045 μg/mL in the DCM and control groups, respectively. Retinol and cholecalciferol levels were both statistically lower in the DCM group than in the control group (p < 0.05). The mean plasma α-tocopherol levels were 0.3103 and 0.4322 μg/mL, and the mean plasma phylloquinone levels were 0.03780 and 0.04082 μg/mL in the DCM and control groups, respectively. However, no statistical significance was observed between the two groups for α-tocopherol or phylloquinone levels. Based on our findings, alterations in vitamin A and D metabolism could be associated with the development of idiopathic DCM in dogs. However, given the limited sample size, further investigation in larger populations is needed.

Background: Observational studies have linked vitamin K and cancer, but the causality of this association remains unknown. This Mendelian randomization (MR) study aims to investigate the association between circulating phylloquinone (vitamin K1) levels and four female-specific cancers. Methods: We used four single-nucleotide polymorphisms (SNPs) to instrument phylloquinone, with the reported F-statistic 16.00–28.44 for all variants. SNP–outcome associations were obtained from consortia meta-analyses, UK Biobank, and the FinnGen database (up to 145,257/419,675, 27,446/362,324, 15,181/591,477, and 2211/320,454 cases/controls for breast, ovarian, endometrial, and cervical cancer, respectively). Analyses were conducted using five complementary MR methods including pleiotropy robust approaches. The MR Egger intercept test, MR PRESSO global test and leave-one-out analyses were used to test for and identify pleiotropic variants. Results: The relevance of the instrument was validated by positive control analyses on coagulation factor IX (p = 0.01). However, the main MR analysis and all sensitivity analyses were consistently supportive of a null association between phylloquinone and all four cancers (p > 0.05 for all analyses, across all methods). MR-PRESSO did not detect outlying variants, and there was no evidence of horizontal pleiotropy relating to any cancer outcome (pintercept > 0.26 for all). Conclusions: We found no evidence for an association between genetically predicted circulating phylloquinone levels and the risk of four female-specific cancers.

Parenteral vitamin K1 (phytonadione) is used for anticoagulant reversal, and a boxed warning exists with intravenous and intramuscular administration due to the possibility of severe reactions, including fatalities. These reactions resemble hypersensitivity or anaphylaxis, including anaphylactoid reaction, and have led to shock and cardiac and/or respiratory arrest. The objective of this review is to summarize the available literature detailing the anaphylactic/anaphylactoid reactions with parenteral vitamin K1 in order to better characterize the reaction and provide a more in-depth understanding of its importance. A comprehensive literature search of MEDLINE (1946 to June 2016) and EMBASE (1947 to June 2016) was conducted using the terms vitamin K1, phytonadione, phytomenadione, vitamin K group, anaphylaxis, polyoxyethylated castor oil, and cremophor. A total of 2 retrospective surveillance studies, 2 retrospective cohort studies, and 17 case reports were identified for inclusion and assessment. Based on a review of the literature, use of parenteral vitamin K1 may result in severe hypotension, bradycardia or tachycardia, dyspnea, bronchospasm, cardiac arrest, and death. These reactions are most consistent with a nonimmune-mediated anaphylactoid mechanism. It appears that intravenous administration is more frequently associated with these reactions and occurs at an incidence of 3 per 10 000 doses of intravenous vitamin K1. The solubilizer may also increase the risk of adverse reactions, which occurred in patients with and without previous exposure to vitamin K1. Although there are known factors that increase the risk of an adverse drug event occurring, reactions have been reported despite all precautions being properly followed.

Background Using vitamin K for correction of coagulopathy in critically ill patients is controversial with limited evidence. This study aims to evaluate the efficacy and safety of vitamin K in the correction of international normalized ratio (INR) elevation secondary to liver disease in critically ill patients. Method A retrospective study of critically ill patients with coagulopathy secondary to liver disease. The primary outcome was to evaluate the association between vitamin K administration and the incidence of new bleeding events in critically ill patients with INR elevation; other outcomes were considered secondary. Patients were categorized into two groups based on vitamin K administration to correct INR elevation. The propensity score was generated based on disease severity scores and the use of pharmacological DVT prophylaxis. Results A total of 98 patients were included in the study. Forty-seven patients (48%) received vitamin K during the study period. The odds of the new bleeding event was not statistically different between groups (OR 2.4, 95% CI 0.28-21.67, P = .42). Delta of INR reduction was observed with a median of 0.63 when the first dose is given (P-value: <.0001). However the INR reduction with other subsequent doses of vitamin K was not statistically significant. Conclusion The administration of vitamin K for INR correction in critically ill patients with coagulopathy secondary to liver disease was not associated with a lower odds of new bleeding events. Further studies are needed to assess the value of vitamin K administration in critically ill patients with liver diseases related coagulopathy.