Static and dynamic characteristics of DFB lasers with longitudinalnonuniformity

Static and dynamic characteristics of 1.55-μm distributed-feedback (DFB) lasers with longitudinal nonuniformity in optical intensity and carrier density are discussed. The nonuniformity is manifested in soft light-current threshold and varying differential quantum efficiency, blue-shifted static tuning, and free-carrier induced FM response     

RNA virus in Allomyces arbuscula: ultrastructural localization during the life-cycle

Three experiments were concerned with tolerance to anorexia induced by d-amphetamine. In experiment 1, one group of rats on a 2 hr food deprivation schedule received 2 mg/kg of d-amphetamine 15 min before eating every other day for a month. A second group of rats on a similar schedule received the same dose of d-amphetamine immediately after eating. When compared to a saline-treated control group, the former group showed significant decreases in weight and food intake; tolerance to the amphetamine-induced anorexia began to occur toward the end of the experiment. The latter group showed a significant decrease in food intake on the non-drug days and an overall weight loss when compared to the control group. Experiment 2 demonstrated that tolerance to d-amphetamine-anorexia was related to the duration of drug administration per se. Experiment 3 showed that taste can be a factor in influencing the rate of tolerance to d-amphetamine-induced anorexia. These results indicate that both pharmacological and experiential factors play an important role in determining the rate of tolerance to this action of d-amphetamine.     

Phosphatidylinositol 3-kinase is involved in the induction of macrophage growth by oxidized low density lipoprotein

Early atherosclerotic lesions are characterized by the presence of cholesterol-rich, macrophage-derived foam cells. It has recently been shown that macrophage proliferation occurs during the development of early lesions and that oxidized low density lipoprotein (LDL) stimulates macrophage growth. Possible mechanisms for this induction of macrophage growth include potentiation of mitogenic signal transduction by a component of oxidized LDL following internalization and degradation, interaction with integral plasma membrane proteins coupled to signaling pathways, or direct or indirect activation of growth factor receptors on the cell surface (e.g. GM-CSF receptor) through an autocrine/paracrine mechanism. The present study was undertaken to characterize some of the early intracellular signaling events by which oxidized LDL mediates macrophage cell growth. Extensively oxidized LDL increased protein-tyrosine phosphorylation and caused a 2-fold increase in phosphatidylinositol (PI) 3-kinase activity in phorbol ester-pretreated THP-1 cells (a human monocyte-like cell line). Similar concentrations of native LDL had no effect. Oxidized LDL also stimulated growth of resident mouse peritoneal macrophages, and this effect was reduced by 40-50% in cells treated with PI 3-kinase inhibitors (100 nM wortmannin or 20 microM LY294002). These results suggest that PI 3-kinase mediates part of the mitogenic effect of oxidized LDL, but parallel pathways involving other receptors and signal transduction pathways are likely also involved.     

40-Gb/s tandem electroabsorption modulator

In this letter, we have developed a tandem electroabsorption modulator with an integrated semiconductor optical amplifier that is capable of both nonreturn-to-zero and return-to-zero (RZ) data transmission at 40 Gb/s. The tandem modulator consists of a broad-band data encoder and a narrow-band pulse carver. The pulse carver is able to produce 5-ps pulses with more than 20 dB of extinction. The on-chip semiconductor optical amplifier provides up to 8.5 dB of fiber-to-fiber gain and enables the modulator to be operated with zero insertion loss. Devices have been realized with greater than 40-GHz bandwidth, and 13-dB dynamic extinction for a 2.5-V swing. For optimized designs bandwidths of nearly 60 GHz: have been realized. Using these devices penalty free RZ data transmission over a 100-kin dispersion compensated fiber link has been demonstrated with a received power sensitivity of -29 dBm     

Expression of prostaglandin receptors EP4 and FP in human lens epithelial cells

Physicians have at their disposal a great number of established diagnostic tests, and new ones continue to be developed that are potentially helpful in diagnosing and establishing the prognosis of disease. Many of these tests were either inadequately evaluated or were found, on more careful scrutiny, to be less helpful than first believed. To ensure optimal patient care as well as appropriate use of health care resources, practitioners must be adept in understanding the true efficacy of diagnostic tests that they ask patients to undergo. They must be able to understand the basic language applied in evaluating tests and be able to determine if and when tests are applicable. (J Am Assoc Gynecol Laparosc 6(1):105-112, 1999)     

High- and low-bar squatting techniques during weight-training

STUDY DESIGN: Tissues in the area of herniated lumbar discs were examined for inflammatory cytokines to elucidate the causes of sciatic pain in lumbar disc herniation. OBJECTIVES: To determine the role of inflammatory cytokines in the stimulation of sciatic pain in lumbar disc herniation. SUMMARY OF BACKGROUND DATA: It is postulated that in addition to mechanical compression of lumbar nerve roots and sensory root ganglia by herniated discs, there is a chemical stimulus to the production of sciatic leg pain. The exact mechanisms of chemical stimulation are not clearly defined. METHODS: During surgery, cases of lumbar disc herniation in 77 patients were classified macroscopically into protrusion, extrusion, and sequestration types. Tissues adjacent to nerve roots at the herniation were excised and analyzed biochemically and immunohistochemically for the presence of inflammatory cytokines and for the production of these cytokines and prostaglandin E2 in vitro. RESULTS: The homogenates of samples were analyzed for interleukin-1 alpha, interleukin-1 beta, interleukin-6, tumor necrosis factor-alpha, and granulocyte-macrophage colony stimulating factor, which were detectable. Most of the cytokine-producing cells were histiocytes, fibroblasts, or endothelial cells in extrusion and sequestration types, and chondrocytes in protrusion type. The secretion of these cytokines and prostaglandin E2 was decreased by the addition of betamethasone. The prostaglandin E2 production was dramatically enhanced by additional interleukin-1 alpha, but decreased by the addition of tumor necrosis factor-alpha. CONCLUSION: The results demonstrate that at the site of lumbar disc herniation, inflammatory cytokines such as interleukin-1 alpha are produced, which increases prostaglandin E2 production. Further studies are required to elucidate the role of inflammatory cytokines in causing sciatic pain.