Resistance at the brain receptors for leptin and insulin has been associated with increased feeding, obesity and cognitive impairments. The causal agent for central resistance is unknown but could be ...derived from the blood. Here we postulate whether hypertriglyceridemia, the major dyslipidemia of the metabolic syndrome, could underlie central leptin and insulin resistance.
We used radioactively labeled triglycerides to measure blood-brain barrier (BBB) penetration, western blots to measure receptor activation, and feeding and cognitive tests to assess behavioral endpoints.
Human CSF was determined to contain triglycerides, a finding previously unclear. The radioactive triglyceride triolein readily crossed the BBB and centrally administered triolein and peripherally administered lipids induced in vivo leptin and/or insulin resistance at hypothalamic receptors. Central triolein blocked the satiety effect of centrally administered leptin. Decreasing serum triglycerides with gemfibrozil improved both learning and memory inversely proportionate to triglyceride levels.
Triglycerides cross the blood-brain barrier rapidly, are found in human cerebrospinal fluid, and induce central leptin and insulin receptor resistance, decreasing satiety and cognition.
In stratified oligotrophic waters, phytoplankton communities forming the deep chlorophyll maximum (DCM) are isolated from atmospheric iron sources above and remineralized iron sources below. Reduced ...supply leads to a minimum in dissolved iron (dFe) near 100 m, but it is unclear if iron limits growth at the DCM. Here, we propose that natural iron addition events occur regularly with the passage of mesoscale eddies, which alter the supply of dFe and other nutrients relative to the availability of light, and can be used to test for iron limitation at the DCM. This framework is applied to two eddies sampled in the North Pacific Subtropical Gyre. Observations in an anticyclonic eddy center indicated downwelling of iron‐rich surface waters, leading to increased dFe at the DCM but no increase in productivity. In contrast, uplift of isopycnals within a cyclonic eddy center increased supply of both nitrate and dFe to the DCM, and led to dominance of picoeukaryotic phytoplankton. Iron addition experiments did not increase productivity in either eddy, but significant enhancement of leucine incorporation in the light was observed in the cyclonic eddy, a potential indicator of iron stress among Prochlorococcus. Rapid cycling of siderophores and low dFe:nitrate uptake ratios also indicate that a portion of the microbial community was stressed by low iron. However, near‐complete nitrate drawdown in this eddy, which represents an extreme case in nutrient supply compared to nearby Hawaii Ocean Time‐series observations, suggests that recycling of dFe in oligotrophic ecosystems is sufficient to avoid iron limitation in the DCM under typical conditions.
Key Points
Both cyclonic and anticyclonic eddies add iron to the lower euphotic zone of oligotrophic gyres
In an anticyclonic eddy, dissolved iron at the deep chlorophyll maximum increased but productivity did not
Uptake of upwelled iron and nitrate in a cyclonic eddy led to low iron conditions and stress, but did not limit productivity
Orthopedic infections are typically treated with intravenous antibiotics. In this trial, 1054 participants with complex orthopedic infections were assigned to receive either oral or intravenous ...antibiotics for the first 6 weeks of treatment. At 1 year, oral therapy was noninferior to intravenous therapy.
Although common sense suggests that environmental influences increasingly account for individual differences in behavior as experiences accumulate during the course of life, this hypothesis has not ...previously been tested, in part because of the large sample sizes needed for an adequately powered analysis. Here we show for general cognitive ability that, to the contrary, genetic influence increases with age. The heritability of general cognitive ability increases significantly and linearly from 41% in childhood (9 years) to 55% in adolescence (12 years) and to 66% in young adulthood (17 years) in a sample of 11 000 pairs of twins from four countries, a larger sample than all previous studies combined. In addition to its far-reaching implications for neuroscience and molecular genetics, this finding suggests new ways of thinking about the interface between nature and nurture during the school years. Why, despite life's 'slings and arrows of outrageous fortune', do genetically driven differences increasingly account for differences in general cognitive ability? We suggest that the answer lies with genotype-environment correlation: as children grow up, they increasingly select, modify and even create their own experiences in part based on their genetic propensities.
To identify the skin temperature in different body areas of hospitalised individuals in the surgical unit, without risk of developing a pressure ulcer (PU).
A descriptive, correlational and ...cross-sectional study, carried out May-October 2017, in a surgical unit of a university hospital in southern Brazil. Temperature was measured at the bony prominences including scapula, elbow, trochanters and heels, on both sides of the body, as well as occipital and sacral regions.
A total of 230 patients took part in the study. All regions of the body measured presented differences in temperatures. The sacral region presented the highest mean temperature (34.2±0.1°C). Patients (aged 18-59 years) had higher skin temperatures in the sacral region than older patients (aged 60-88 years). There was a symmetry in temperatures on both sides of the body. There was a low degree of correlation between age, room temperature, room humidity and skin temperature in some body regions.
The study established mean values for skin temperature in specific body regions in patients without risk of developing a PU, hospitalised in a surgical unit. It also demonstrates how skin temperature can be used as a clinical parameter in practice to support the prevention of PUs.
Abstract The enlarged size of the aortic bulb is thought to enhance the ability of marine mammals to remain underwater for extended periods. However, a convincing link between aortic bulb size and ...diving capacity has not been established. Using new and existing data, we examined the relationships between body size, maximum and routine dive duration, and aortic bulb size of pinnipeds. Comparisons among seven species of pinnipeds showed that the diameter of the aortic bulb increases allometrically with body mass (aortic bulb diameter = 0.58 × body mass 0.41 ). We also found a linear relationship between routine dive duration and relative aortic bulb diameter (routine dive duration = 0.20 × relative aortic bulb diameter − 3.30), but no apparent relationship with maximum dive duration. Our results indicate that relative aortic bulb diameter influences diving capacity, providing further evidence that the aortic bulb is an adaptation to diving. Specifically, the relative diameter of the aortic bulb partially determines how long pinnipeds can routinely remain underwater. This has implications for the ability of different species of marine mammals to adapt to projected environmental changes and effectively forage or evade threats in altered habitats.
Although the ability of marine mammals to lower heart rates for extended periods when diving is well documented, it is unclear whether marine mammals have electrophysiological adaptations that extend ...beyond overall bradycardia. We analyzed electrocardiographic data from 50 species of terrestrial mammals and 19 species of marine mammals to determine whether the electrical activity of the heart differs between these two groups of mammals. We also tested whether physiological state (i.e., anesthetized or conscious) affects electrocardiogram (ECG) parameters. Analyses of ECG waveform morphology (heart rate, P-wave duration, and PQ, PR, QRS, and QT intervals) revealed allometric relationships between body mass and all ECG intervals (as well as heart rate) for both groups of mammals and specific differences in ECG parameters between marine mammals and their terrestrial counterparts. Model outputs indicated that marine mammals had 19% longer P-waves, 24% longer QRS intervals, and 21% shorter QT intervals. In other words, marine mammals had slower atrial and ventricular depolarization, and faster ventricular repolarization than terrestrial mammals. Heart rates and PR intervals were not significantly different between marine and terrestrial mammals, and physiological state did not significantly affect any ECG parameter. On average, ECG interval durations of marine and terrestrial mammals scaled with body mass to the power of 0.21 (range: 0.19–0.23) rather than the expected 0.25—while heart rate scaled with body mass to the power of –0.22 and was greater than the widely accepted –0.25 derived from fractal geometry. Our findings show clear differences between the hearts of terrestrial and marine mammals in terms of cardiac timing that extend beyond diving bradycardia. They also highlight the importance of considering special adaptations (such as breath-hold diving) when analyzing allometric relationships.
The increased size and enhanced compliance of the aortic bulb—the enlargement of the ascending aorta—are believed to maintain blood flow in pinnipeds during extended periods of diastole induced by ...diving bradycardia. The aortic bulb has been described ex vivo in several species of pinnipeds, but in vivo measurements are needed to investigate the relationship between structure and function. We obtained ultrasound images using electrocardiogram‐gated transesophageal echocardiography during anesthesia and after atropine administration to assess the relationship between aortic bulb anatomy and cardiac function (heart rate, stroke volume, cardiac output) in northern fur seals (Callorhinus ursinus) and Steller sea lions (Eumetopias jubatus). We observed that the aortic bulb in northern fur seals and Steller sea lions expands during systole and recoils over the entire diastolic period indicating that blood flow is maintained throughout the entire cardiac cycle as expected. The stroke volumes we measured in the fur seals and sea lions fit the values predicted based on body size in mammals and did not change with increased heart rates, suggesting that greater stroke volumes are not needed for aortic bulb function. Overall, our results suggest that peripheral vasoconstriction during diving is sufficient to modulate the volume of blood in the aortic bulb to ensure that flow lasts over the entire diastolic period. These results indicate that the shift of blood into the aortic bulb of pinnipeds is a fundamental mechanism caused by vasoconstriction while diving, highlighting the importance of this unique anatomical adaptation.
Research highlights
Aortic bulb expansion and recoil supported continuous blood flow in northern fur seals and Steller sea lions. Stroke volumes in these species matched predictions based on body size, suggesting that having a large aortic bulb does not necessitate having a greater stroke volume to support diving.
Methicillin-resistant Staphylococcus aureus (MRSA) strains are a leading cause of communicable disease in community and nosocomial settings. They are responsible for high morbidity and mortality. ...Researchers currently pursue novel antimicrobials from natural sources against non-traditional drug targets of staphylococci to ensure a pipeline of potent drugs, in the face of rising drug resistance. The focus of this study was to screen compounds from a freshwater isolate of Chlorella sorokiniana for anti-staphylococcal activity, using traditional microbiology, phytochemical analysis and bioinformatics approaches.
Chlorella sorokiniana methanol extract was investigated for its antimicrobial potential on Staphylococcus aureus strains (ATCC and MRSA isolates) by Kirby Bauer disc diffusion, broth microdilution, cell cytotoxicity and thin layer chromatography-bioautography (TLC-BA). Two antimicrobial TLC-BA antimicrobial fractions (A and B) were subject to gas chromatography mass spectrometry (GCMS). The structures of 9 compounds representing GCMS peaks were tested in silico, for their pharmacokinetic properties and binding energy efficiency with the target, using Molinspiration tool and Autodock 4.2.
Mean zone diameter of inhibition of growth by CSME (20 mg) was 21 mm, MIC/MBC was 0.31/2.5 mg/L. GCMS analysis of TLC fraction-A revealed 31 phytochemicals, of which 2-pentanone,4-hydroxy-4-methyl- had the highest area % (65.61) and TLC fraction-B revealed 4 peaks of which pentadecanoic acid and 1-(+)-ascorbic acid 2,6-dihexadecanoate had the highest area % (45.57, 48.09).
In silico analysis of 9 peak compounds on the target of interest showed that compound 2: 2-pentanone,4-hydroxy-4-methyl- and compound 7: 1,2 – benzene dicarboxylic acid, mono (2- ethylhexyl) ester, satisfied Lipinski’s rule of 5, and displayed the least binding energies −6.93 and −5.74 with ClpP protease, thus holding pharmaceutical potential, and supporting further investment into in vitro and in vivo studies.
C. sorokiniana, a less studied microalga thus offers a promising natural resource for anti-MRSA phytochemicals, capable of targeting ClpP1 protease.
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