In a bent optical fiber, lateral internal stress induces a birefringence, betab. At lambda = 0.633 microm in a silica fiber, betab = 7.7 X 10(7) r2 /R2 deg/m, where r is the fiber radius and R is the bending radius.
The backscattered light amplitude is measured from one end of a fiber as a function of optical frequency by tuning a HeNe laser over its linewidth. Fourier transform by a low-frequency electronic spectrum analyzer then reveals the spatial distribution of scattering and of the fiber losses.
Fiber-optic sensors are described that utilize the mode-mode interference of the two orthogonal linear polarizations of the HE(11), mode in strongly birefringent single-mode fibers. The sensitivities of various versions of these one-fiber interferometers are calculated. When fibers with high internal stress are used, the temperature sensitivity is reduced by only a factor of 50 compared with that of two-fiber interferometers while the pressure sensitivity is reduced by 7.3 x 10(3). Thus the cross sensitivity is reduced by a factor of 150.
Human leukocyte elastase (HLE) has been proposed as a primary mediator of pulmonary emphysema and other inflammatory airway diseases. HLE is capable of cleaving many proteins, including elastin, other components of connective tissue, certain complement proteins, and receptors. Under normal conditions an appropriate balance exists in the lung between HLE and endogenous inhibitors, which scavenge the released enzyme before it exerts deleterious effects in the lung. Emphysema is thought to result from an imbalance in the lung between HLE and endogenous inhibitor (elevated elastase or insufficient inhibitor) that leads to the destruction of alveoli. We have identified WIN 64733 (2) and WIN 63759 (3) as potent (Ki* = 14 and 13 pM, respectively), selective, mechanism-based inhibitors of HLE which are orally bioavailable in the dog (absolute bioavailability 46% and 21%, respectively). In this series the in vitro stabilities of the inhibitors in blood, jejunal homogenates, and liver S9 homogenates are useful predictors of oral bioavailability. After being administered orally (30 mgkg) to dogs, compounds 2 and 3 are found in the lung, being detected in the epithelial lining fluid obtained by bronchoalveolar lavage (C,,, of 2.5 and 0.47 pg/mL, respectively).Human leukocyte elastase (HLE) has been proposed as a primary mediator of pulmonary emphysema and other inflammatory airway diseases. HLE is capable of cleaving many proteins, including elastin, other components of connective tissue, certain complement proteins, and receptorsa2 Under normal conditions an appropriate balance exists in the lung between HLE and endogenous inhibitors, which scavenge the released enzyme before it exerts deleterious effects in the lung. In response to inflammatory mediators, HLE and other proteases are released from the granules of neutrophils. An imbalance between HLE and endogenous inhibitory
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