The effects of a novel "fluid loading" strategy on the cardiovascular and haematological responses to orthostatic stress

Patients restricted to bed rest and astronauts exposed to microgravity experience large reductions in body mass (BM), total body water (TBW), plasma volume (PV) and skeletal muscle mass which can lead to orthostatic intolerance, and as yet there are no effective countermeasures. A novel fluid loading strategy combining creatine (Cr) and glycerol (Gly) results in a significant increase in BM, TBW and PV, which may attenuate some of the detrimental physiological effects of immobilisation.PURPOSE: To examine the cardiovascular and haematological responses to orthostatic stress following supplementation with Cr and Gly.METHODS: 10 male subjects were subjected to 3 postural tilt tests designed to induce orthostatic stress, during which they lay supine for 30 min followed by a further 30 min in the 70° head up position. Following two baseline experimental trials, subjects ingested 20 g Cr and 1 g Gly·kg-1 BM each day for 7 days, flavoured with 200 ml diluting juice made up in 1 L of warm water.RESULTS: Tilting subjects from the supine position to 70° resulted in a significant mean increase in heart rate of 16 beats·min-1 indicating a significant orthostatic challenge with no difference between experimental trials. During both baseline trials, 3 subjects experienced hypotension and syncope during the 70° head up tilt phase. Following supplementation, BM increased (mean ± S.D.) by 0.9±0.3 kg, TBW by 0.7±0.2 L and PV by 3.2±2.4%. Cr and Gly supplementation resulted in a significantmean increase in systolic (11 mmHg; P=0.02) and diastolic (7 mmHg; P=0.04) blood pressure during the tilt test and a reduced incidence of orthostatic hypotension and presyncope.CONCLUSIONS: These data suggest that the expansion of body water compartments through Cr/Gly supplementation coupled with the purported anabolic properties of Cr may prove an effective countermeasure to combat orthostatic intolerance in patients exposed to prolonged periods of bed rest and astronauts following spaceflight

Relationship between Graft-vs-Host Reactivity and Possession of the High Leukemia Genotype <i>hr/hr</i>

Summary The immunologic reactivity of hr/hr and hr/ + mice of the HRS strain was studied by the graft vs host (GVH) assay. Spleen cells from hr/+ donors caused significantly greater GVH reactions than did spleen cells from hr/hr mice. These results suggest that genetically determined immunologic hyporesponsiveness may contribute to the high leukemia susceptibility of hr/hr mice.</jats:p

Haptic discrimination of different types of pencils during writing

Professional artists seem to develop a preference for certain types of pencils and paper (Akyuz 1995). While the aesthetic outcome may be the obvious reason for this preference, haptic feedback may also play a role in selecting media (Prytherch and Jerrard 2001, 2003). This suggestion implies that artists may be sensitive to vibrotactile signals resulting from the interaction between pencil and paper during drawing. Tribological tests showed that H-range leads generate more resistance than B-range pencils when writing on a standard 80 g/m2 paper. Moreover, a constant stimulus 2IFC procedure showed that Fine Arts students found it easier to discriminate between H-range and HB than B-range and an HB. This suggests that the human haptic system may be sensitive to the vibrotactile signals generated by the differences in resistance resulting from the interaction of leads with the paper's textured surface. Implications for pencil manufacturing and simulations of virtual writing are discussed. Statement of Relevance: The study assesses the tactile sensitivity of Fine Artists to the physical properties of the interaction between different types of lead and a standard printing paper. The results may help in designing more responsive drawing instruments as well as more realistic virtual drawing interfaces. © 2011 Taylor &amp; Francis

Integrated principles of zoology

xiv, 882 p. ; 28 c