Application of phosphatidic acid in sport: reality or myth?

The mTOR enzyme plays an important role in the transmission of extracellular signals through the phosphorylation of numerous substrates in various metabolic reactions of the human body. Expression of mTOR occurs in response to changes in metabolic demands of the muscle cell and leads to increased protein metabolism. Among the substances that increase the catalytic activity of mTOR one of the main places is occupied by phosphatidic acid, the content of which in skeletal muscles increases when performing physical exertion. Studies of recent years indicate the important role of phosphatidic acid in increasing the intensity of the synthesis of muscle proteins. So, there is the need to consider the current state of knowledge about the involvement of phosphatidic acid in the regulation of skeletal muscle metabolism. The review presents the results of studies published over the last few years, which expand the understanding of the effects of phosphatidic acid in the human body

Dental status of persons engaged in sports swimming

To date, information on the problem is contradictory and ambiguous. It is difficult to trace cause – effect relationships between the condition of hard dental tissues, oral fluid, the dental status of swimmers, and the characteristics of the water environment of training pools. The article presents an analysis and systematization of literature on the dental condition in swimming athletes, as well as formulates modern ideas on the subject and highlights topics for further research

Condition of hard tissues of teeth and oral fluid in athletes-swimmers

Objective: to determine the state of dental hard tissues and saliva parameters changing in competitive swimmers, before and after a 2­hour training session in the chlorinated water swimming pool.Materials and methods: saliva parameters of competitive swimmers trained in the sport club “Grifon”, city of St. Petersburg, Russia (n = 21), age of participants 18.1 ± 3.5 years, qualifications (1 category­Master of Sports) and track and field athletes of the sports schools “Nevsky district” and “Orlyonok”, city of St. Petersburg, Russia (n = 18), age of participants 18.80 ± 4.54 years, qualifications (1 category — Master of Sports), have been analyzed by various tests include a study of calcium (Ca), phosphorus (P), fluorine (F) levels, and pH before and after training sessions. All athletes in the experimental and control groups have passed an examination by dentist, including: examination of the oral cavity with the determination of the KPU index (the sum of carious, filled and removed permanent teeth in the subject), examination of the most common places of occurrence of dental enamel erosion (medical binoculars) and filling out specially designed questionnaires.Results: there was a tendency to decrease of the average saliva pH in competitive swimmers’ group after a training session, varying from 6.9 ± 0.1 (before training) to 6.5 ± 0.1 (after training) (p > 0.05). In track and field athletes, saliva pH did not change significantly (7.1 ± 0.2 before training and 7.0 ± 0.1 after training) (p < 0.05). The competitive swimmers showed a statistically significant increase in Calcium (Ca) levels (1.25 ± 0.15 mmol/L before exercise and 1.56 ± 0.11 mmol/L after exercise) and Fluorine (F) (0.0010 ± 0.0003 mmol / L before exercise and 0.0090 ± 0.0004 mmol / L after training session) in saliva. The Phosphorus (P) level in saliva was significantly reduced after the training session (from 6.09 ± 0.39 to 3.89 ± 0.46 mmol / L) (p > 0.05). In track and field athletes, there were no significant changes in Ca, F and P levels before and after a training session. As a result of the dentist’s examination, competitive swimmers were found to have 3 athletes (14.3 %) with lesions of the teeth enamel, corresponding to dental erosion and caused by localized demineralization. In the control group of athletes, no such pathologies were revealed.Conclusion: discovered saliva parameters changing in competitive swimmers (decrease in free salivation, pH level, and increase in the level of Ca and F in saliva) can contribute to the demineralization of tooth enamel. Timely and controlled use of fluorides (as part of mouth rinses, application gels, fluoride varnishes), regular preventive dental examinations, in order to prevent the loss of mineral composition of the teeth when swimming in chlorinated pools, will minimize the risk of staining and dental enamel erosions

Chemically active substitutional nitrogen impurity in carbon nanotubes

We investigate the nitrogen substitutional impurity in semiconducting zigzag and metallic armchair single-wall carbon nanotubes using ab initio density functional theory. At low concentrations (less than 1 atomic %), the defect state in a semiconducting tube becomes spatially localized and develops a flat energy level in the band gap. Such a localized state makes the impurity site chemically and electronically active. We find that if two neighboring tubes have their impurities facing one another, an intertube covalent bond forms. This finding opens an intriguing possibility for tunnel junctions, as well as the functionalization of suitably doped carbon nanotubes by selectively forming chemical bonds with ligands at the impurity site. If the intertube bond density is high enough, a highly packed bundle of interlinked single-wall nanotubes can form.Comment: 4 pages, 4 figures; major changes to the tex

Myocardial damage biomarkers and the first case of macrotroponin I detection in endurance athletes

Background. High levels of cardiac troponin in the blood indicates myocardial injury, including those caused by intense exercises. Recent studies have shown that an elevation in the troponin concentration in the patients can be caused by the macrotroponin circulation. There is no data in the scientific literature describing this problem in athletes.The aim. To identify the cases and possible causes of high blood levels of cardiac markers in athletes before and after endurance exercises.Materials and methods. The study was conducted on 11 male cross-country skiers aged 15–21 years. The study included two stages: the first was conducted at the end of the preparatory period (November, 2020–2021), the second – in the middle (March) of the 2020–2021 competitive period. At each stage, two blood samples were taken from a vein: the first – in the morning on an empty stomach after a day of rest, the second – 12–14 hours after a high-intensity exercise. In the blood serum, the activity of total creatine kinase (CK), weight concentration of the cardiac isoenzyme of creatine kinase (CK-MB), and concentration of high sensitive troponin I (Tn) were measured.Results. The activity of CK in athletes exceeded the upper limit threshold, and decreased from the preparatory (November) to the competitive (March) period. The concentration of CK-MB in response to exercise increased by 2 times and was not accompanied by the signs of myocardial injury. The most sensitive indicator, responsive to physical activity, was troponin I. However, the highest elevation of Tn in blood of one athlete, both before and after the exercise, was associated with the presence of macrotroponin without signs of myocardial injury.Conclusions. An increase of muscle tissue injury biomarkers in blood, including the heart muscle (CK, CK-MB, and Tn), by 2–4 times is a typical reaction for the body of a cross-country skier to an intense exercise. High levels of troponin in the blood, both before and after training or competition, may be associated with the presence of macrotroponin

Colonization, disability, and the intranet: the ethnic cleansing of space?

The article analyzes teacher’s emplacement of the image of disability within school’s intranet sites in England. The image unearthed within such sites was problematic as it did not display a positive or realistic image of disability or disabled people. Within the article historical archaeology and colonialism are employed as theoretic framework to interpret this artifact of disability. The article also provides an ethnographic subscript to the creation of a space of possibilities and how this became striated by missionary teachers who colonized this brave new intranet world. Deciphering of the organization and representation of the disabled indigene, through this theoretical framework, unearthed a cartography inscribed by the scalpel of old world geometry

Towards a three-dimensional microfluidic liver platform for predicting drug efficacy and toxicity in humans

Although the process of drug development requires efficacy and toxicity testing in animals prior to human testing, animal models have limited ability to accurately predict human responses to xenobiotics and other insults. Societal pressures are also focusing on reduction of and, ultimately, replacement of animal testing. However, a variety of in vitro models, explored over the last decade, have not been powerful enough to replace animal models. New initiatives sponsored by several US federal agencies seek to address this problem by funding the development of physiologically relevant human organ models on microscopic chips. The eventual goal is to simulate a human-on-a-chip, by interconnecting the organ models, thereby replacing animal testing in drug discovery and development. As part of this initiative, we aim to build a three-dimensional human liver chip that mimics the acinus, the smallest functional unit of the liver, including its oxygen gradient. Our liver-on-a-chip platform will deliver a microfluidic three-dimensional co-culture environment with stable synthetic and enzymatic function for at least 4 weeks. Sentinel cells that contain fluorescent biosensors will be integrated into the chip to provide multiplexed, real-time readouts of key liver functions and pathology. We are also developing a database to manage experimental data and harness external information to interpret the multimodal data and create a predictive platform. © 2013 BioMed Central Ltd

Single step process for the synthesis of carbon nanotubes and metal/alloy-filled multiwalled carbon nanotubes

A single-step approach for the synthesis of multi-walled nanotubes (MWNT) filled with nanowires of Ni/ternary Zr based hydrogen storage alloy has been illustrated. We also demonstrate the generation of CO-free hydrogen by methane decomposition over alloy hydride catalyst. The present work also highlights the formation of single-walled nanotubes (SWNT) and MWNTs at varying process conditions. These carbon nanostructures have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM), Energy dispersive X-ray analysis (EDX) and Raman spectroscopy. This new approach overcomes the existing multi-step process limitation, with possible impact on the development of future fuel cell, nano-battery and hydrogen sensor technologies