Distal/proximal ratio

This apparent dilema was resolved when further crystallographic data on T3 compounds became available (11,12,13,14,15). (See reference 11 for a detailed list of thyroactive crystal structure studies.) These determinations show the 3 -I in the distal conformation and further showed that either the distal or proximal conformer could be isolated by changing the crystallizing media (13,14). These data prompted further NMR and MQ studies which showed a nearly equal distal/proximal ratio in solution (16) and a much smaller barrier to internal rotation (17). Thus these data have shown that the distal and proximal conformers are readily accessible in solution and that the energy barrier to free rotation is small enough so that the stereospecific conformer required by a receptor is easily accessible. 

CVSF = conduction velocity of slow = motor fibers dSCV = distal sensory nerve conduction velocity MAP k/a = proximal to distal amplitude ratio of muscle action potentials MMCV = maximal motor nerve conduction velocity MNCV = mixed nerve conduction velocity RL = residual latency of motor nerve conduction... 

Bulge Composition (X) Distal/Proximal GG Cleavage Ratio... 

The fate of dissolved Fe from MOR vents has been investigated at the Rainbow plume from the mid-Atlantic Ridge. Plume particles were sampled from the buoyant part of the Rainbow plume, proximal to the vent, as well as particles from neutrally buoyant portions of the plume that were more distal from the vent (Severmann et al. 2003). Particles from the buoyant part of the plume have positive 5 Fe values (up to +1.2%o), whereas in the neutrally buoyant sections of the plume, the particles have a near-constant 8 Fe value of -0.2%o that matches the Fe isotope composition of the vent fluid. The high 5 Fe values of plume particles that were proximal to the vent probably reflect oxidation processes. In the neutrally-buoyant plume, all aqueous Fe(ll) had been oxidized and it appears that there was no net loss in Fe because the neutrally buoyant plume particles have the same isotopic composition as the vent fluid. Moreover, metalliferous sediments sampled below the plume match the isotopic composition of the plume particles. The implication of these data is that for at least one plume, the Fe isotope composition of the vent fluid matches that of the plume particles. The Rainbow vent fluid, however, has an unusually high Fe to S ratio and hence it is uncertain if these results can be extrapolated to other plumes that originated fi om vent fluids that had lower Fe to S ratios. 

Fig. 9.18 The polymer spacer concept for the construction of a biomimetic cell membrane on solids. Mesogenic units, coupling groups and the flexible polymer can be combined either in form of a statistical terpolymer (above). Variation of the ratio of the three monomers allows an easy tuning of the system. In an alternative system, an end-functio-nalized linear hydrophilic polymer chain bearing a coupling group at the proximal and the mesogen at the distal end was employed.

The Co/Ni of type 1 pyrite from distal samples is 0.15-0.5 compared with 1.0-4.0 in proximal samples, consistent with the results of Loftus-Hill and Solomon (1967) who recorded ratios of 0.03-0.4 and 0.8 respectively (note that the distal samples in this earlier study are largely from shale units closer to the Hellyer ore body). 

TABLE 3 Distal to Proximal GG Cleavage Ratio as a Function of Bulge Composition ... 

Figure 9.3 Inhibition of intimal hyperplasia by resveratrol in rabbits subjected to endothelial injury by denudation. Groups of eight New Zealand white rabbits, weighting 2.2 to 3.6 kg, were assigned randomly to control (untreated) (M), low (2 mg/kg/d) (L), and high dose (4 mg/kg/d) (H) resveratrol treatment, which was administered intragastrically for 5 weeks beginning 1 week before surgery. A 2-cm segment of injured iliac artery was excised, fixed in 4% paraformalin, embedded in paraffin, and sectioned at5-mm intervals from the proximal to the distal end. Representative sections were stained with hematoxylin/eosin. The external and internal elastic lamina were manually identified. Intimal proliferation index (IPI) was defined as the ratio of intimal area to [intimal+medial] area relative luminal area (RLA) was defined as the ratio of luminal area to [luminal+intimal+medial] area.

As was seen previously for model system 5, the ratio of proximal to distal dia-stereomers 14/15 displays a Lewis acid dependence (Table 10-8). The reactions strongly favor the anti Se- pathway (selectivities >95%) regardless of the Lewis acid employed and regardless of the relative stereochemical outcome. Reactions with either diastereomer (/)- or (m)-13 gave identical results, therefore only the results obtained with /-13 are presented. The only divergence from this behavior is seen when fluoride ion was used to initiate the reaction. With fluoride, the distal... 

Remarkably, the ratio of proximal to distal products was dependent upon the mode of cyclization (syn versus anti Se ). Cyclization through the syn Sp pathway led to the predominant formation of the distal products (8/1), whereas cyclization... 

When plasma HCOJ concentration increases above 28 mmol/L, the capacity of the proximal and distal tubules to reclaim is exceeded, and HCOf is excreted in the urine. The process of bicarbonate reclamation is enhanced in acidosis (and decreased in alkalosis), most likely as a result of increased Na -H exchange. In this way, the kidneys in acidosis or alkalosis support the other compensatory mechanisms to restore the normal cHC03/cdC02 ratio. Type II RTA is a decreased ability to reabsorb HCO3 in the proximal tubules, leading to a decrease in blood pH. 

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