1,963 research outputs found
Greenland during the last interglacial:the relative importance of insolation and oceanic changes
Insolation changes during the Eemian (the last interglacial period,
129 000–116 000 years before present) resulted in warmer than present
conditions in the Arctic region. The NEEM ice core record suggests
warming of 8 ± 4 K in northwestern Greenland based on stable water
isotopes. Here we use general circulation model experiments to investigate
the causes of the Eemian warming in Greenland. Simulations of the atmospheric
response to combinations of Eemian insolation and preindustrial oceanic
conditions and vice versa are used to disentangle the impacts of the
insolation change and the related changes in sea surface temperatures and sea
ice conditions. The changed oceanic conditions cause warming throughout the
year, prolonging the impact of the summertime insolation increase.
Consequently, the oceanic conditions cause an annual mean warming of 2 K at
the NEEM site, whereas the insolation alone causes an insignificant change.
Taking the precipitation changes into account, however, the insolation and
oceanic changes cause more comparable increases in the precipitation-weighted
temperature, implying that both contributions are important for the ice core
record at the NEEM site. The simulated Eemian precipitation-weighted warming
of 2.4 K at the NEEM site is low compared to the ice core reconstruction,
partially due to missing feedbacks related to ice sheet changes and an
extensive sea ice cover. Surface mass balance calculations with an energy
balance model further indicate that the combination of temperature and
precipitation anomalies leads to potential mass loss in the north and
southwestern parts of the ice sheet. The oceanic conditions favor increased
accumulation in the southeast, while the insolation appears to be the
dominant cause of the expected ice sheet reduction. Consequently, the Eemian
is not a suitable analogue for future ice sheet changes
Superparamagnetic iron oxide polyacrylic acid coated {\gamma}-Fe2O3 nanoparticles does not affect kidney function but causes acute effect on the cardiovascular function in healthy mice
This study describes the distribution of intravenously injected polyacrylic
acid (PAA) coated {\gamma}-Fe2O3 NPs (10 mg kg-1) at the organ, cellular and
subcellular levels in healthy BALB/cJ mice and in parallel addresses the
effects of NP injection on kidney function, blood pressure and vascular
contractility. Magnetic resonance imaging (MRI) and transmission electron
microscopy (TEM) showed accumulation of NPs in the liver within 1h after
intravenous infusion, accommodated by intracellular uptake in endothelial and
Kupffer cells with subsequent intracellular uptake in renal cells, particularly
the cytoplasm of the proximal tubule, in podocytes and mesangial cells. The
renofunctional effects of NPs were evaluated by arterial acid-base status and
measurements of glomerular filtration rate (GFR) after instrumentation with
chronically indwelling catheters. Arterial pH was 7.46 and 7.41 in mice 0.5 h
after injections of saline or NP, and did not change over the next 12h. In
addition, the injections of NP did not affect arterial PCO2 or [HCO3-] either.
Twenty-four and 96h after NP injections, the GFR averaged 11.0 and 13.0 ml
min-1 g-1, respectively, values which were statistically comparable with
controls (14.0 and 14.0 ml min-1 g-1). Mean arterial blood pressure (MAP)
decreased 12-24h after NP injections (111 vs 123 min-1) associated with a
decreased contractility of small mesenteric arteries revealed by myography to
characterise endothelial function. In conclusion, our study demonstrates that
accumulation of superparamagnetic iron oxide nanoparticles does not affect
kidney function in healthy mice but temporarily decreases blood pressure.Comment: 21 pages, 12 figures, published in Toxicology and Applied
Pharmacology 201
Dretske & McDowell on perceptual knowledge, conclusive reasons, and epistemological disjunctivism
The HK2 Dependent "Warburg Effect" and Mitochondrial Oxidative Phosphorylation in Cancer:Targets for Effective Therapy with 3-Bromopyruvate
This review summarizes the current state of knowledge about the metabolism of cancer cells, especially with respect to the “Warburg” and “Crabtree” effects. This work also summarizes two key discoveries, one of which relates to hexokinase-2 (HK2), a major player in both the “Warburg effect” and cancer cell immortalization. The second discovery relates to the finding that cancer cells, unlike normal cells, derive as much as 60% of their ATP from glycolysis via the “Warburg effect”, and the remaining 40% is derived from mitochondrial oxidative phosphorylation. Also described are selected anticancer agents which generally act as strong energy blockers inside cancer cells. Among them, much attention has focused on 3-bromopyruvate (3BP). This small alkylating compound targets both the “Warburg effect”, i.e., elevated glycolysis even in the presence oxygen, as well as mitochondrial oxidative phosphorylation in cancer cells. Normal cells remain unharmed. 3BP rapidly kills cancer cells growing in tissue culture, eradicates tumors in animals, and prevents metastasis. In addition, properly formulated 3BP shows promise also as an effective anti-liver cancer agent in humans and is effective also toward cancers known as “multiple myeloma”. Finally, 3BP has been shown to significantly extend the life of a human patient for which no other options were available. Thus, it can be stated that 3BP is a very promising new anti-cancer agent in the process of undergoing clinical development
Inside Out: Modern Imaging Techniques to Reveal Animal Anatomy
Animal anatomy has traditionally relied on detailed dissections to produce anatomical illustrations, but modern imaging modalities, such as MRI and CT, now represent an enormous resource that allows for fast non-invasive visualizations of animal anatomy in living animals. These modalities also allow for creation of three-dimensional representations that can be of considerable value in the dissemination of anatomical studies. In this methodological review, we present our experiences using MRI, CT and ÎĽCT to create advanced representation of animal anatomy, including bones, inner organs and blood vessels in a variety of animals, including fish, amphibians, reptiles, mammals, and spiders. The images have a similar quality to most traditional anatomical drawings and are presented together with interactive movies of the anatomical structures, where the object can be viewed from different angles. Given that clinical scanners found in the majority of larger hospitals are fully suitable for these purposes, we encourage biologists to take advantage of these imaging techniques in creation of three-dimensional graphical representations of internal structures
Lasting effects of workplace strength training for neck/shoulder/arm pain among laboratory technicians:Natural experiment with 3-year follow-up
Objectives. This study investigated long-term effects and implementation processes of workplace strength training for musculoskeletal disorders. Methods. 333 and 140 laboratory technicians from private and public sector companies, respectively, replied to a 3-year follow-up questionnaire subsequent to a 1-year randomized controlled trial (RCT) with high-intensity strength training for prevention and treatment of neck, shoulder, and arm pain. Being a natural experiment, the two participating companies implemented and modified the initial training program in different ways during the subsequent 2 years after the RCT. Results. At 3-year follow-up the pain reduction in neck, shoulder, elbow, and wrist achieved during the first year was largely maintained at both companies. However, the private sector company was rated significantly better than the public sector company in (1) training adherence, (2) training culture, that is, relatively more employees trained at the workplace and with colleagues, (3) self-reported health changes, and (4) prevention of neck and wrist pain development among initially pain-free employees. Conclusions. This natural experiment shows that strength training can be implemented successfully at different companies during working hours on a long-term basis with lasting effects on pain in neck, shoulder, and arm
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