Tricyclic hydrocarbon fluorene attenuates ventricular ionic currents and pressure development in the navaga cod.

The release of polycyclic aromatic hydrocarbons (PAHs) into the environment due to oil and diesel fuel spills is a serious threat to Arctic fish populations. PAHs produce multiple toxic effects in fish, but disturbance of electrical and contractile activity of the heart seems to be the most negative effect. Our study focused on the effects of fluorene, a tricyclic PAH resembling the well-investigated tricyclic phenanthrene, on major ionic currents and action potential (AP) waveform in isolated ventricular myocytes and on contractile activity in isolated whole hearts of polar navaga cod (Eleginus nawaga). Among the studied currents, the repolarizing rapid delayed rectifier K+ current IKr demonstrated the highest sensitivity to fluorene with IC50 of 0.54 µM. The depolarizing inward currents, INa and ICaL, were inhibited with 10 µM fluorene by 20.2 ± 2.8 % and 27.9 ± 8.4 %, respectively, thereby being much less sensitive to fluorene than IKr. Inward rectifier IK1 current was insensitive to fluorene (up to 10 µM). While 3 µM fluorene prolonged APs, 10 µM also slowed the AP upstroke. Resting membrane potential was not affected by any tested concentrations. In isolated heart experiments 10 µM fluorene caused modest depression of ventricular contractile activity. Thus, we have demonstrated that fluorene, a tricyclic PAH present in high quantities in crude oil, strongly impacts electrical activity with only slight effects on contractile activity in the heart of the polar fish, the navaga cod.

A Cohort Mortality Study Among Soviet and Russian Cosmonauts, 1961-2014.

INTRODUCTION: Over 500 people from different countries have been to space since the first manned spaceflight in 1961. Factors of space and spaceflights might cause functional and somatic disorders, leading to increased mortality. Our research goal was to assess cause-specific risk of death among Soviet and Russian cosmonauts who had at least one spaceflight. METHODS: The epidemiological cohort study included 115 male cosmonauts. The observation period was 54 yr (January 1, 1961-December 31, 2014) and 2707 person-years of follow-up were obtained. By the end of the period, 84 cosmonauts were still alive and 31 were deceased. The reference groups were the male population of Russia and of the Moscow Region, where Zvezdny City (Star City) is located. Mortality risk was assessed by standardized mortality ratio (SMR) with 95% confidence intervals (95% CI). RESULTS: Death risk in the cohort was significantly lower than that in both reference groups: for all causes (А00-Y98; SMR = 40), for diseases of the circulatory system (I00-I99; SMR = 37 and 35 compared to Russia and the Moscow Region, respectively), and for other causes, i.e., all causes except circulatory diseases, cancer, and accidents, (SMR = 8). Death risk for accidents (V01-Y98) in the cohort was 1.8-1.9 times lower than that in both reference groups: SMR = 52 (95% CI 19-139) and 56 (21-151), but was not statistically significant. SMR for cancer (C00-C97) was also below 100 (71 and 66), but insignificant. DISCUSSION: Our findings mainly characterize mortality among the first cosmonauts who have flown to space from 1961 through the 1970s, which indicates the necessity of continuing research.Ushakov IB, Voronkov YI, Bukhtiyarov IV, Tikhonova GI, Gorchakova TYu, Bryleva MS. A cohort mortality study among Soviet and Russian cosmonauts, 1961-2014. Aerosp Med Hum Perform. 2017; 88(12):1060-1065.

Medical qualification of a commercial spaceflight participant: not your average astronaut.

BACKGROUND: Candidates for commercial spaceflight may be older than the typical astronaut and more likely to have medical problems that place them at risk during flight. Since the effects of microgravity on many medical conditions are unknown, physicians have little guidance when evaluating and certifying commercial spaceflight participants. This dynamic new era in space exploration may provide important data for evaluating medical conditions, creating appropriate medical standards, and optimizing treatment alternatives for long-duration spaceflight. CASE: A 57-yr-old spaceflight participant for an ISS mission presented with medical conditions that included moderately severe bullous emphysema, previous spontaneous pneumothorax with talc pleurodesis, a lung parenchymal mass, and ventricular and atrial ectopy. The medical evaluation required for certification was extensive and included medical studies and monitoring conducted in analogue spaceflight environments including altitude chambers, high altitude mixed-gas simulation, zero-G aircraft, and high-G centrifuge. To prevent recurrence of pneumothorax, we performed video-assisted thoracoscopic pleurodesis, and to assess lung masses, several percutaneous or direct biopsies. The candidate's 10-d mission was without incident. CONCLUSION: Non-career astronauts applying for commercial suborbital and orbital spaceflight will, at least in the near future, challenge aerospace physicians with unknowns regarding safety during training and flight, and highlight important ethical and risk-assessment problems. The information obtained from this new group of space travelers will provide important data for the evaluation and in-flight treatment of medical problems that space programs have not yet addressed systematically, and may improve the medical preparedness of exploration-class missions.