Fisheries, low oxygen and climate change: how much do we really know?

The negative effects of copper on Macoma balthica are significantly increased when this bivalve is simultaneously exposed to low oxygen concentrations. This might be explained by the fact that low oxygen concentrations (oxygen deficiency) are combined with a slightly lower pH and thus with a different copper speciation, resulting in a higher bio-availability of copper and, consequently, in a higher copper uptake by M. balthica. Symptomatic for the increased negative effects of copper on M. balthica at low oxygen concentrations is an increased oxygen demand, which in turn reflects an increased consumption of energy. Consequently, at low oxygen levels, low copper concentrations (8–15 μg dm-3) greatly affect the glycogen content of the tissues, and finally (at 15 μg Cu dm-3) result in a heavy loss of dry weight and a drastic reduction of the adenylate energy charge (AEC). Generally, it might be concluded that dry weight, glycogen content and AEC are more affected by a combination of oxygen deficiency and a low copper concentration (2.5 cm3 O2 dm-3, 15 μg Cu dm-3) than by higher copper concentrations (up to 86 μg dm-3) at high oxygen levels (5.0 cm3 dm-3).

Experimental and numerical study on suitable diesel fuel surrogates in low temperature combustion conditions

Nocturnal hypoxia-induced oxidative stress promotes progression of pediatric non-alcoholic fatty liver disease

One of the parameters potentially affecting the in vitro growth of preimplantation embryos is the oxygen concentration in the culture environment. An increased oxygen concentration causes the generation of ROS which in turn can cause damage to the cells and seriously disrupt the embryonic development. Previous studies have assessed oxygen concentrations in the fallopian tubes of several mammals of between 5 and 8%, while the oxygen levels in the uterus were found to be even lower; similar measurements have been confirmed in humans. In addition, studies in mammalian embryos showed that low oxygen concentrations improve embryo development. Multiple studies on the effect of the oxygen concentration on human embryos have been conducted so far with diverse methodologies and objectives. Data from these have been included in three meta-analyses. All meta-analyses indicate the potential benefit in favor of a low oxygen concentration, though data are considered to be of a low methodological quality and further studies are considered necessary. However, based on the existing evidence, it is suggested that a low oxygen concentration should be adopted in the routine of the IVF laboratory, especially in the case of blastocyst culture.

The effect of oxygen pressure on the swimming activity of hemoglobin-rich (red) and hemoglobin-poor (pale) Ceriodaphnia quadrangula was studied at 25?C. The swimming time of red animals until final cessation of antennal movement was constant (38 min) in extremely low oxygen concentration, rapidly increased, and reached 100 min at 4.5 torr. The swimming time of pale animals was constant (24 min) at 3.5 torr, increased gradually, and reached 100 min at 11.7 torr. The swimming time of red animals in nitrogen-saturated water increased on exposure to 3.5 torr and reached a maximum of 35 min at 5.8 torr. The swimming time of pale animals increased above 10.5 torr and reached a maximum of 23 min at 16.3 torr. Hemoglobin commonly occurs in the hemolymph of Ceriodaphnia (Hoshi, 1957; Czeczuga, 1965; Kobayashi and Hoshi, 1983). As in many other cladocerans (Fox et al., 1949, 1953; Green, 1955; Kobayashi and Hoshi, 1982; Kobayashi and Nezu, 1986), the concentration of Ceriodaphnia-hemoglobin varies considerably with environmental oxygen concentration. Hemoglobin-rich (red) animals are normally found in water of low oxygen concentration, while hemoglobin-poor (pale) animals are found in well-aerated water (Czeczuga, 1965; Kobayashi and Hoshi, 1983). In general, the physiological function of hemoglobin in small invertebrates has been estimated from the reduction of oxygen consumption of animals after inactivation of their hemoglobin with carbon monoxide (Prosser, 1973; Weber, 1980). In cladocerans, pale animals have been used as natural controls for comparison with red animals, because of the marked difference in the hemoglobin concentrations between them (Kobayashi, 1974; Kobayashi and Gonoi, 1985). Functional significance of Ceriodaphnia-hemoglobin has been evaluated from the swimming distance in a glass tube (150 cm long) in pale, red, and carbon monoxide-treated red animals (Kobayashi and Yoshida, 1986). The swimming speed (43 cm/min) did not differ between pale and red animals. They both swam a distance of 5 m in oxygen pressure of 2.3 torr. At 4.7 torr, red animals swam more than 80 m, whereas pale animals swam only 7 m. Further increase in oxygen pressure induced an increase in the swimming distance of pale animals which reached 100 m at 21 torr. In red animals treated with carbon monoxide, oxygen pressures demonstrated almost the same effect on the swimming activity as in pale animals. Apparently hemoglobin allowed red animals to take up oxygen in low oxygen environment and to swim a longer distance than pale or carbon monoxide-treated animals even in low oxygen pressure. In oxygen-regulating animals, the critical oxygen concentration (below which the oxygen consumption depends on ambient oxygen concentration) has been determined, to study their responses to low environmental oxygen (Mangum and Van Winkle, 1973; Herreid, 1980; Lubbers, 1980). When the swimming distance was measured by the above-mentioned method (Kobayashi and Yoshida, 1986), the swimming distance was found to increase exponentially with an increase in oxygen concentration and even to exceed the upper limit of measurement. By the use of this method, therefore, it is not possible to estimate the oxygen concentration equivalent to the critical oxygen concentration.

Experimental investigation and evaluation of influence of oxygen concentration on characteristic parameters of coal spontaneous combustion

The present study was conducted to clarify the effects of oxygen concentration under various leaf temperatures on the growth of wheat and rice plants (C3-plants). Seedlings of both species were growth for 7 days in specially devised growth chamber equiped with water culture facilities, under 2.5% O2, 0.03% CO2 and 21% O2, 0.03% CO2, and at light intensity 45 Klx (at 20. 25 and 30°C leaf temperature) or 25 Klx (at 5 and 10°C) under a regime of 12hr light and 12hr darkness. The growth paramenters of the plants were investigated at the start and the end of each experiment. The results obtained are summarized as follows: 1. The dry matter production (ΔWT and RGR) was enhanced in both species under overall leaf temperatures, and plant height and leaf emergence were somewhat inhibited except at 30°C in wheat and 20°C in rice plant with low oxygen ooncentration. 2. NAR of both species enlarged extremely at low oxygen concentration under overall leaf temperatures. According to these results, it can be deduced that acceleration of the apparent photosynthetic rate at low oxygen concentration, due to suppression of the photorespiration et al., persists for a long time. 3. NAR and RGR were enhanced under low leaf temperature (5 and 10°C) at low oxygen concentration, therefore these results suggest that the function of photorespiratory mechanism still may continue under low leaf temperature. 4. It has been shown that the apparent photosynthetic rate increases at low oxygen concentration with leaf temperature increases, and it reaches maximum rate at 30∼35°C. However, RGR of both species at low oxygen concentration in this experiment was greatest at 20°C and it decreased with falling or rising temperature. It is considered that at low oxygen concentration the optimum temperature for the apparent photosynthetic rate as momentary value does not fit the maximum growth of plants. On the other hand, difference between RGR at low oxygen concentration and RGR at normal air was greater under higher temperature, hence it can be explained that the effect of suppression of the photrespiration et al., on the dry matter production is greater under higher temperature. 5. RLGR was reduced under low oxygen concentration, and subsequently decreasing of LAR came out. In spite of decrease of LAR, RGR was increased through greater increase of NAR under low oxygen concentration. 6. The surplus dry matter in plants under low oxygen concentration (ΔW at 2.5%O2-ΔW at 21% O2) was allotted to leaf blades and roots in wheat, and leaf sheaths+stems and roots in rice plant, respectively. It may be considered that above difference was based on the characteristics of species.

Objective To study the efficacy of neoadjuvant chemotherapy plus radiotherapy with inspiring high and low concentration oxygen respectively in invasive bladder cancer. Methods All 31 patients with invasive bladder cancer underwent bladder sparing treatment, who rejected or could not bear total cystectomy.The neoadjuvant treatment protocol consisted of chemotherapy two cycles and radiotherapy with inspiring high and low concentration oxygen respectively. Those patients who obtained partial response or recurred in the follow-up period were treated with bladder sparing operation. Results After neoadjuvant therapy, 22 patients (71.0 %) showed a complete response (CR) and 9 patients (29.0 %) showed a partial response (PR). Total nine patients accepted extensive transurethral resection or partial cystectomy, one of four cases accepted the second operation due to local recurrence. Conclusion Neoadjuvant chemotherapy and radiotherapy with inspiring high and low concentration oxygen respectively is an effective method for partial patients with invasive bladder cancer, especially for those who can not tolerate burden or reject total cystectomy. Key words: Bladder neoplasms; Chemotherapy; Radiotherapy; Oxygen

Initial resuscitation with air is well tolerated by most infants born at term. However, the optimal fractional inspired oxygen concentration (FiO2 - proportion of the breathed air that is oxygen) targeted to oxygen saturation (SpO2 - an estimate of the amount of oxygen in the blood) for infants born preterm is unclear. To determine whether lower or higher initial oxygen concentrations, when titrated according to oxygen saturation targets during the resuscitation of preterm infants at birth, lead to improved short- and long-term mortality and morbidity. We conducted electronic searches of the Cochrane Central Register of Controlled Trials (13 October 2017), Ovid MEDLINE (1946 to 13 October 2017), Embase (1974 to 13 October 2017) and CINAHL (1982 to 13 October 2017); we also searched previous reviews (including cross-references), contacted expert informants, and handsearched journals. We included randomised controlled trials (including cluster- and quasi-randomised trials) which enrolled preterm infants requiring resuscitation following birth and allocated them to receive either lower (FiO2 < 0.4) or higher (FiO2 ≥ 0.4) initial oxygen concentrations titrated to target oxygen saturation. Two review authors independently assessed the eligibility of studies for inclusion, extracted data and assessed methodological quality. Primary outcomes included mortality near term or at discharge (latest reported) and neurodevelopmental disability. We conducted meta-analysis using a fixed-effect model. We assessed the quality of the evidence using GRADE. The search identified 10 eligible trials. Meta-analysis of the 10 included studies (914 infants) showed no difference in mortality to discharge between lower (FiO2 < 0.4) and higher (FiO2 ≥ 0.4) initial oxygen concentrations targeted to oxygen saturation (risk ratio (RR) 1.05, 95% confidence interval (CI) 0.68 to 1.63). We identified no heterogeneity in this analysis. We graded the quality of the evidence as low due to risk of bias and imprecision. There were no significant subgroup effects according to inspired oxygen concentration strata (FiO2 0.21 versus ≥ 0.4 to < 0.6; FiO2 0.21 versus ≥ 0.6 to 1.0; and FiO2 ≥ 0.3 to < 0.4 versus ≥ 0.6 to 1.0). Subgroup analysis identified a single trial that reported increased mortality from use of lower (FiO2 0.21) versus higher (FiO2 1.0) initial oxygen concentration targeted to a lowest SpO2 of less than 85%, whereas meta-analysis of nine trials targeting a lowest SpO2 of 85% to 90% found no difference in mortality.Meta-analysis of two trials (208 infants) showed no difference in neurodevelopmental disability at 24 months between infants receiving lower (FiO2 < 0.4) versus higher (FiO2 > 0.4) initial oxygen concentrations targeted to oxygen saturation. Other outcomes were incompletely reported by studies. Overall, we found no difference in use of intermittent positive pressure ventilation or intubation in the delivery room; retinopathy (damage to the retina of the eyes, measured as any retinopathy and severe retinopathy); intraventricular haemorrhage (any and severe); periventricular leukomalacia (a type of white-matter brain injury); necrotising enterocolitis (a condition where a portion of the bowel dies); chronic lung disease at 36 weeks' gestation; mortality to follow up; postnatal growth failure; and patent ductus arteriosus. We graded the quality of the evidence for these outcomes as low or very low. There is uncertainty as to whether initiating post birth resuscitation in preterm infants using lower (FiO2 < 0.4) or higher (FiO2 ≥ 0.4) oxygen concentrations, targeted to oxygen saturations in the first 10 minutes, has an important effect on mortality or major morbidity, intubation during post birth resuscitation, other resuscitation outcomes, and long-term outcomes including neurodevelopmental disability. We assessed the quality of the evidence for all outcomes as low to very low. Further large, well designed trials are needed to assess the effect of using different initial oxygen concentrations and the effect of targeting different oxygen saturations.

Oxygen availability is key in determining habitat suitability for marine fish. As a result of climate change, low oxygen conditions are predicted to occur more frequently and over a greater geographic extent. Studies assessing the long-term chronic effects and impacts for commercially important fish are rare. To assess the potential effects of climate-induced low oxygen on fisheries, physiological data, such as critical thresholds, derived from laboratory experiments on 5 commercial fish species were integrated with hindcast and future oxygen projections from the hydrodynamic-biogeochemical model GETM-ERSEM. By using this approach, changes in habitat suitability from the 1970s to 2100 were identified. In the North Sea, the current extent of areas with the lowest oxygen levels is smaller than during the 1970s, with improved oxygen conditions having less impact on species’ critical thresholds. Oxygen levels are expected to decrease again in the coming century due to climate change, although not to the minima of previous decades. In affected areas and years, intermediate oxygen levels could have temporary impacts in late summer on swimming, growth, ingestion and metabolic scope of adult fish. These results demonstrate that although physical model oxygen projections help to provide insight, they are insufficient by themselves to predict the full potential impacts of climate change on fish distribution and fisheries. Such modelling requires underpinning through experimentation, particularly of the physiological effects of climate change on different life stages so that effects on reproduction, growth and commercial catches can be determined and tailored, and robust management measures put in place.

Phytosanitary irradiation (PI) has been successfully used to disinfest fresh commodities and facilitate international agricultural trade. Critical aspects that may reduce PI efficacy must be considered to ensure the consistency and effectiveness of approved treatment schedules. One factor that can potentially reduce PI efficacy is irradiation under low oxygen conditions. This factor is particularly important because storage and packaging of horticultural commodities under low oxygen levels constitute practices widely used to preserve their quality and extend their shelf life. Hence, international organizations and regulatory agencies have considered the uncertainties regarding the efficacy of PI doses for insects infesting fresh commodities stored under low oxygen levels as a rationale for restricting PI application under modified atmosphere. Our research examines the extent to which low oxygen treatments can reduce the efficacy of phytosanitary irradiation for tephritids naturally infesting fruits. The effects of normoxia (21% O2), hypoxia (~5% O2), and severe hypoxia (< 0.5% O2) on radiation sensitivity of third instars of Anastrepha fraterculus (sensu lato), A. ludens (Loew), Bactrocera dorsalis (Hendel), and Ceratitis capitata (Wiedemann) were evaluated and compared at several gamma radiation doses. Our findings suggest that, compared to normoxia, hypoxic and severe-hypoxic conditioning before and during irradiation can increase adult emergence and contribute to advancement of larval development of tephritid fruit flies only at low radiation doses that are not used as phytosanitary treatments. With phytosanitary irradiation doses approved internationally for several tephritids, low oxygen treatments applied before and during irradiation did not increase the emergence rates of any fruit fly species evaluated, and all treated insects died as coarctate larvae. Thus, the findings of our research support a re-evaluation of restrictions related to phytosanitary irradiation application under modified atmospheres targeting tephritid fruit flies.

The proliferative response of murine lymphocytes to interleukin-2 (IL-2) was examined under physico-chemical conditions present in solid tumours, namely low oxygen and glucose concentrations and acidic pH. Lymphocytes were cultured for four days in 30 U ml-1 IL-2 to simulate serum IL-2 concentrations attainable with high-dose systemic IL-2 therapy. Lymphocyte proliferation was significantly (P < 0.05) reduced by low oxygen concentrations (both anoxia [0% O2] and hypoxia [10%, low glucose (6 mg dl-1), or acidic pH (6.7 or 6.4). Moderate glucose concentration (32 mg dl-1), or neutral pH (7.0) did not impair proliferation. This study indicates that impairment of lymphocyte proliferation by tumour physico-chemical conditions may be a factor in the relatively poor success rate of IL-2/LAK cell immunotherapy.

Gas effects on void formation in 14 MeV nickel ion irradiated pure nickel

In this experiment, we carried out a two-step deoxidation process to obtain Ti ingots with low oxygen concentration from commercial Ti powder. The first step was to primarily reduce oxygen in Ti powder using Ca and the second was to melt the deoxidized Ti powder in Ar atmosphere with added hydrogen using a vacuum arc melting system. We used two types of raw Ti powder, one with a high oxygen concentration of 5,600ppm and average powder size of 35µm, and the other with 2,200ppm and 115µm. The high oxygen of 5,600ppm in the Ti powder was reduced to approximately 1,460ppm by the two-step process of melting after deoxidizing the Ti powder with Ca at 973K. On the other hand, in the case of the Ti powder with low oxygen of 2,200ppm, the Ti ingot with low oxygen of 600ppm could be prepared by the twostep process of melting after deoxidizing at 1,103K. The Vickers hardness and c/a value of Ti ingots decreased as the oxygen concentration decreased. [doi:10.2320/matertrans.M2012004]

Three species (central mudminnow, fathead minnow and brook stickleback) survive when a northern Wisconsin lake becomes anoxic in winter. Some gas bubbles beneath the ice contained as much as 11° oxygen when the lake water contained <0.30 mg 1−1 dissolved oxygen. Experiments conducted in the field determined that gas bubbles prolonged survival of all species, especially the mudminnow and stickleback. In the laboratory, brook sticklebacks exhibited the lowest and fathead minnows the highest routine metabolic rate corrected for weight. Rate of gill ventilation of all three increased from 20 to 70 beats per minute as oxygen levels declined from 4.0 to 0.25 mg 1−1. At low oxygen levels they moved to the upper one-third of the test tanks. Small size, low metabolic rate, tolerance of low oxygen conditions and reduced activity resulted in reduced demand for dissolved oxygen. Head shape, ventilation rate, vertical movement and utilization of high oxygen microzones also enhanced exploitation of low levels of dissolved oxygen. Central mudminnows used oxygen directly from gas bubbles found under the ice.