Link between methyl nutrients and the DNA methylation process in the course of selected diseases in adults

DNA methylation is a reversible epigenetic modification that plays a crucial role in transcriptional gene silencing. Both excessive (hypermethylation) and reduced DNA methylation (hypomethylation) can contribute to the disturbance of the proper course of many important processes in the human body. The aim of the study was to discuss the relationship between methyl nutrients and the DNA methylation process in the course of selected diseases in adults. Methyl nutrients include folates (vitamin B9), riboflavin (vitamin B2), cobalamin (vitamin B12), pyridoxine (vitamin B6) and choline (vitamin B4), as well as methionine and betaine. These substances play the role of both substrates and cofactors in transformations related to one-carbon metabolism. The deficiency of methyl nutrients in the body can lead to disturbances in SAM synthesis, which is the primary donor of methyl groups in the DNA methylation process. However, the mechanism explaining the discussed relationship has not been fully explained so far. Both the concentration in the body and the intake of folate and vitamin B12 in the diet can, to some extent, have an effect on the level of DNA methylation in healthy people. In comparison, data on the effect of excessive intake of vitamin B12 in the diet on the risk of cancer development are inconsistent. An adequate betaine and choline intake in the diet might not only affect the overall improvement of the DNA methylation profile, but, to some extent, also reduce the risk of cancer, the effect of which can depend on the content of folic acid in the body. Research results on the effect of supplementation of methyl nutrients on the DNA methylation process are inconclusive. It is therefore necessary to conduct further research in this area to draw clear conclusions.

Propeller Flaps in the Posterior Trunk

The reconstruction of complex posterior trunk defects remains challenging. But now with an increased knowledge of angiosomes and the practice of perforator flaps, the posterior trunk offers a new plethora of options for reconstruction. Propeller flaps based on such perforator(s) offer an elegant solution for managing defects while achieving primary donor-site closure without significant morbidity. We will discuss the relevant anatomy and design principles for propeller flaps based on a review of the literature and our experience. Steps beginning with preoperative planning, perforator selection, and intraoperative surgical technique will be discussed, together with pearls on both avoiding and managing complications.

Propeller Flaps for the Anterior Trunk

Various types of propeller flaps from multiple donor sites can be used to reconstruct anterior trunk skin defects. The actual selection depends on the condition and location of the recipient site, especially if it is to be the chest or abdomen that requires attention. Before surgery commences, it is always important to use an imaging analyses such as computed tomography angiography to examine and identify perforators that could perfuse a perforator-pedicled propeller flap (PPPF), as it is the most multifaceted imaging technique. Clusters of perforators that can be commonly used for the “workhorse” PPPFs for the thoracic and abdominal regions are the internal mammary artery perforator, the musculophrenic artery perforator, and the deep inferior epigastric perforator. These perforators are reliable and large enough to support long and large propeller flaps that will cover most defects in this region, while still allowing primary donor-site closure.

The primary donor of far-red Photosystem II: ChlD1 or PD2?

ABSTRACTFar-red light (FRL) Photosystem II (PSII) isolated from Chroococcidiopsis thermalis is studied using parallel analyses of low-temperature absorption, circular dichroism (CD) and magnetic circular dichroism (MCD) spectroscopies in conjunction with fluorescence measurements. This extends earlier studies (Nurnberg et al 2018 Science 360 (2018) 1210-1213). We confirm that the chlorophyll absorbing at 726 nm is the primary electron donor. At 1.8 K efficient photochemistry occurs when exciting at 726 nm and shorter wavelengths; but not at wavelengths longer than 726 nm. The 726 nm absorption peak exhibits a 21 ± 4 cm−1 electrochromic shift due to formation of the semiquinone anion, QA•-. Modelling indicates that no other FRL pigment is located among the 6 central reaction center chlorins: PD1, PD2 ChlD1, ChlD2, PheoD1 and PheoD2. Two of these chlorins, ChlD1 and PD2, are located at a distance and orientation relative to QA•- so as to account for the observed electrochromic shift. Previously, ChlD1 was taken as the most likely candidate for the primary donor based on spectroscopy, sequence analysis and mechanistic arguments. Here, a more detailed comparison of the spectroscopic data with exciton modelling of the electrochromic pattern indicates that PD2 is at least as likely as ChlD1 to be responsible for the 726 nm absorption. The correspondence in sign and magnitude of the CD observed at 726 nm with that predicted from modelling favors PD2 as the primary donor. The pros and cons of PD2 vs ChlD1 as the location of the FRL-primary donor are discussed.TOC GraphicHighlightsPrimary Donor confirmed at 726 nmDetermination of far-red chl pigment Qy excitation positions, widths, CD and MCD amplitudesQuantification of electrochromic shifts and QA•- photoconversion yieldElectrochromic shift consistent with primary donor at either ChlD1 or PD2The CD amplitude favors the primary donor at PD2

Two-dimensional 67Zn HYSCORE spectroscopy reveals that a Zn-bacteriochlorophyll aP′ dimer is the primary donor (P840) in the type-1 reaction centers of Chloracidobacterium thermophilum

Using pulsed EPR spectroscopy and isotopic labeling we demonstrate that reaction centers of Chloracidobacterium thermophilum have an unusual primary donor that is a dimer of Zn-bacteriochlorophyll aP′ molecules.

Photosystem II does not convert nascent oxygen to the poisonous singlet form

In the light, the Mn4CaO5 complex of Photosystem II (PSII) splits water producing O2 and the triplet state of the primary donor (3P680) of PSII generates reactive singlet oxygen (1O2). We show that nascent O2 is not converted to 1O2, but originates exclusively from ambient O2, indicating that the sensitivity of PSII to oxidative damage is not a consequence of the water-splitting per se, and showing that the suggested oxygen channels function nearly perfectly, conveying nascent O2 out of the reach of 3P680. This may have been crucial during evolution of oxygenic photosynthesis, as 3P680 cannot be quenched by carotenoids that protect non- oxygenic photosystems. In addition, the data indicate that a 1O2-independent mechanism contributes to the light-induced damage of PSII.

Usefulness of Loanwords of Latin Origin for Learning Russian

Latin is the primary donor language to Russian. In this study, a vocabulary survey was conducted to propose the usefulness of frequently used Russian vocabulary of Latin origin and their English equivalents for learners of Russian. The Oxford 3000 was used as the primary reference for the 3,000 most frequently used English words, and the author investigated the frequency of their Russian equivalents. As a result, 411 loanwords of Latin origin were found to be included in the 3,000 most common Russian words. Therefore, the present study concluded that learning basic Russian vocabulary of Latin origin helps English speakers improve their Russian proficiency.

Advantages of Loanwords of Latin Origin for Learning German and Dutch

Latin is the primary donor language to German and Dutch. In this study, a vocabulary survey was conducted to propose the advantages of frequently used German and Dutch vocabulary of Latin origin and their English equivalents for learners of German and Dutch. The Oxford 3000 was used as the primary reference for the 3,000 most frequently used English words, and the author analyzed the frequency of their German and Dutch equivalents. As a result, 432 loanwords of Latin or Greek origin were found to be included in the 3,000 most common German and Dutch words. Therefore, the present study concluded that possessing a knowledge of basic German and Dutch vocabulary of Latin or Greek origin effectively assists English speakers in learning German and Dutch.