Cardiovascular responses to water drinking: does osmolality play a role?

Water drinking activates the autonomic nervous system and induces acute hemodynamic changes. The actual stimulus for these effects is undetermined but might be related to either gastric distension or to osmotic factors. In the present study, we tested whether the cardiovascular responses to water drinking are related to water's relative hypoosmolality. Therefore, we compared the cardiovascular effects of a water drink (7.5 ml/kg body wt) with an identical volume of a physiological (0.9%) saline solution in nine healthy subjects (6 male, 3 female, aged 26 +/- 2 years), while continuously monitoring beat-to-beat blood pressure (finger plethysmography), cardiac intervals (electrocardiography), and cardiac output (thoracic impedance). Total peripheral resistance was calculated as mean blood pressure/cardiac output. Cardiac interval variability (high-frequency power) was assessed by spectral analysis as an index of cardiac vagal tone. Baroreceptor sensitivity was evaluated using the sequence technique. Drinking water, but not saline, decreased heart rate (P = 0.01) and increased total peripheral resistance (P < 0.01), high-frequency cardiac interval variability (P = 0.03), and baroreceptor sensitivity (P = 0.01). Neither water nor saline substantially increased blood pressure. These responses suggest that water drinking simultaneously increases sympathetic vasoconstrictor activity and cardiac vagal tone. That these effects were absent after drinking physiological saline indicate that the cardiovascular responses to water drinking are influenced by its hypoosmotic properties.     

Birds as predators of the pine processionary moth (Lepidoptera: Notodontidae)

The beneficial role of insectivorous birds potentially contributing to the biological control of forest insect pests appears crucial in the context of climate warming, especially for species currently expanding their range such as the pine processionary moth Thaumetopoea pityocampa. Larvae of T. pityocampa are aposematic and carry true urticating setae which, together with overwintering in silk winter nests, prevent them from predation by most insectivorous forest birds. The present review aims at pointing out which bird species can regularly feed on this key forest defoliator throughout its distribution range, and which predation strategies allow birds to cope with the urticating setae carried by late-instar larvae. At least seven bird species can be considered as regular predators of the pine processionary moth: four large migrant specialists (great spotted cuckoo Clamator glandarius, common cuckoo Cuculus canorus, European nightjar Caprimulgus europaeus and Eurasian hoopoe Upupa epops) and three small sedentary generalists (great tit Parus major, crested tit Lophophanes cristatus and coal tit Periparus ater). Each species has developed morphological traits and foraging techniques to feed on different life stages of T. pityocampa throughout the year: (i) gizzard wall structure allowing the consumption of caterpillars with urticating setae (cuckoos); (ii) nocturnal foraging on moth imagos by aerial hawking (nightjars); (iii) ground probing on below-ground pupae with long curved bill (hoopoe); and (iv) shifted predation period in autumn and winter on eggs, early- and late-instar larvae, with particular feeding technique allowing to eat only the inner parts of urticating larvae stages (tits). Although several avian predators regularly feed on T. pityocampa, only a few specialist and generalist insectivorous birds may contribute to regulate its populations, especially when population density of the moth is low. Moreover, their efficiency may possibly be threatened by mismatches associated with climate change.     

Defining the risks of mesenchymal stromal cell therapy

We address the issue of the potential for malignant transformation of cultured mesenchymal stromal cells (MSC) commonly used in clinical cell-therapy protocols and describe the culture conditions under which tumorigenesis is likely to be an extremely uncommon event.     

La 12′-hydroxyisostrychnobiline: Nouvel alcaloïde du Strychnos variabilis

The structure of a new bisindole alkaloid, 12′-hydroxyisostrychnobiline, has been proposed from the analysis of its 300 MHz ¹H NMR spectrum and comparison of the spectroscopic data with those of various monomeric and dimeric alkaloids, previously isolated from the same Strychnos species     

Microtubule alteration is an early cellular reaction to the metabolic challenge in ischemic cardiomyocytes

Cytoskeleton damage, particularly microtubule (MT) alterations, may play an important role in the pathogenesis of ischemia-induced myocardial injury. However, this disorganization has been scarcely confirmed in the cellular context. We evaluated MT network disassembly in myoblast cell line H9c2 and in neonatal rat cardiomyocytes in an in vitro substrate-free hypoxia model of simulated ischemia (SI). After different duration of SI from 30 up to 180 min, the cells were fixed and the microtubule network was revealed by immunocytochemistry. The microtubule alterations were quantified using a house-developed image analysis program. Additionally, the tubulin fraction were extracted and quantified by Western blotting. The cell respiration, the release of cellular LDH and the cell viability were evaluated at the same periods. An early MT disassembly was observed after 60 min of SI. The decrease in MT fluorescence intensity at 60 and 90 min was correlated with a microtubule disassembly. Conversely, SI-induced significant LDH release (35%) and decrease in cell viability (34%) occurred after 120 min only. These results suggest that the simulated ischemia-induced changes in MT network should not be considered as an ultrastructural hallmark of the cell injury and could rather be an early ultrastructural correlate of the cellular reaction to the metabolic challenge.     

Balance control during an arm raising movement in bipedal stance: which biomechanical factor is controlled?

In order to obtain new insight into the control of balance during arm raising movements in bipedal stance, we performed a biomechanical analysis of kinematics and dynamical aspects of arm raising movements by combining experimental work, large-scale models of the body, and techniques simulating human behavior. A comparison between experimental and simulated joint kinematics showed that the minimum torque change model yielded realistic trajectories. We then performed an analysis based on computer simulations. Since keeping the center of pressure (CoP) and the projection of the center of mass (CoM) inside the support area is essential for equilibrium, we modeled an arm raising movement where displacement of one or the other variable is limited. For this optimization model, the effects of adding equilibrium constraints on movement trajectories were investigated. The results show that: (a) the choice of the regulated variable influences the strategy adopted by the system and (b) the system was not able to regulate the CoM for very fast movements without compromising its balance. Consequently, we suggest that the system is able to maintain balance while raising the arm by only controlling the CoP. This may be done mainly by using hip mechanisms and controlling net ankle torque.     

Incorporation of oxyphytosterols in tissues of hamster

Oxyphytosterols (OPS) were fed to hamsters, at different concentrations, in order to observe their eventual incorporation into plasma, aorta, liver, kidneys and heart. The animals receiving the very high level (2500 ppm) presented 7beta-hydroxycampesterol, beta-epoxycampesterol, campestanetriol, 7-ketocampesterol, 7beta-hydroxysitosterol, beta-epoxysitosterol, sitostanetriol and 7-ketositosterol in all tissues. The same compounds were observed in the tissues of animals receiving 500 ppm of OPS in their diet, but with much lower levels. In hamsters fed 100 ppm of OPS, as well as in control animals, in most cases, the only observed OPS was sitostanetriol, which seems to be difficult to eliminate from the animal.     

Versatile synthesis of Boc protected hydrazinoacetic acid and its application to the chemoselective ligation of TASP molecules

This paper describes a convenient synthesis of protected hydrazine derivatives, i.e. 1,2-bis-Boc-hydrazinoacetic acid, and its application for hydrazone ligation techniques in convergent template assembled synthetic protein (TASP) synthesis.     

Salicylate decreases production of AmpC type beta-lactamases and increases susceptibility to beta-lactams in a Morganella morganii clinical isolate

The effect of salicylate, a marRAB inducer, on the resistance to beta-lactams was characterized in an AmpC beta-lactamase hyperproducer Morganella morganii clinical isolate (the M1 strain). Results were compared with those of the effect of salicylate in a wild-type M. morganii strain. Salicylate induced a decreased susceptibility to nalidixic acid, norfloxacin and tetracycline and simultaneously increased the susceptibility to beta-lactams apparently due to the repression of AmpC beta-lactamase synthesis in the M1 strain. Likewise, salicylate only repressed 46 kDa outer membrane protein expression in the wild-type strain, since the clinical isolate M1 did not express it.