Effects of Narrow-Band Filters on the Output Envelopes and Phases of Joint AM-FM Inputs: An Analytical Extension of the Bedrosian-Rice Formulation

The problem of determining the waveform distortion produced by a (symmetrical) narrow-band linear filter when an off-tune, simultaneously amplitude- and angle-modulated carrier is introduced, is analytically solved by an extension of the Bedrosian-Rice approach [1]. Here, both the instantaneous angle and envelope of the resulting narrowband output are determined. These results provide a basis for numerical calculations and extension to the more complex problem of interference effects produced by multiple inputs of the above type.     

Nationwide survey of fluoroscopy: radiation dose and image quality

PURPOSE: To determine the average abdominal entrance air kerma, low-contrast sensitivity, and spatial resolution in upper gastrointestinal tract fluoroscopy in the United States. MATERIALS AND METHODS: A random sample of fluoroscopic facilities was selected to be surveyed for the Nationwide Evaluation of X-ray Trends program. Measurements were performed by using a newly developed fluoroscopic phantom. The surveys were conducted by state radiation control personnel. RESULTS: Average air kerma rates 1 cm above the tabletop, free in air, were 43 mGy/min (n = 340). The rate increased to 64 mGy/min when a 1.6-mm-thick copper filter, which simulated the use of barium contrast medium, was added to increase attenuation. The average entrance air kerma, free in air, for radiographs was 3.4 mGy, and an average of 12 radiographs were obtained per examination. Of 352 facilities surveyed, 306 (87%) were able to resolve wire mesh with 20 or more lines per inch. Of 339 facilities for which percentage contrast could be calculated, 192 (57%) had minimum percentage contrast values of 4% or more. CONCLUSION: Spatial resolution for fluoroscopy is adequate for most of the facilities surveyed, but a substantial proportion of facilities could not visualize low-contrast test objects, which strongly suggests image quality problems.     

Tryptase mediates hyperresponsiveness in isolated guinea pig bronchi

Hyperresponsiveness of airway smooth muscle to allergens and environmental factors has long been associated with the pathophysiology of asthma. Tryptase, a serine protease of lung mast cells, has been implicated as one of the mediators involved in the induction of hyperresponsiveness. As a consequence, tryptase inhibitors have become the subject of study as potential novel therapeutic agents for asthma. Secretory leukocyte protease inhibitor (SLPI) is a naturally occurring protein of human airways which exhibits anti-tryptase activity. To assess the potential therapeutic utility of SLPI in asthma, its effects were evaluated using in vitro and ex vivo models of airway hyperresponsiveness and compared with the effects of the small molecule tryptase inhibitor APC-366. Our results demonstrate that SLPI inhibits tryptase-mediated hyperresponsiveness in vitro and attenuates the hyperresponsiveness observed in airway smooth muscle from antigen-sensitized animals subjected to antigen exposure. The small molecule tryptase inhibitor APC-366 has a similar inhibitory effect. Thus, tryptase appears to be a significant contributor to the development of hyperresponsiveness in these models. To the extent that tryptase contributes to the development and progression of asthma, SLPI may possess therapeutic potential in this disease setting.     

Urocanic acid isomers in patients with basal cell carcinoma and cutaneous malignant melanoma

Urocanic acid (UCA) is a major chromophore for ultraviolet (UV) radiation in the skin. On UV exposure, the naturally occurring trans-isomer converts to the cis-isomer in a dose-dependent manner. Accumulating evidence indicates that cis-UCA acts as an initiator of the UV-induced suppression of certain skin immune functions. This immunomodulation is recognized as an important factor in the development of skin cancer. In this study, pigmentation and UCA isomers were measured in 29 patients with previous basal cell carcinoma (BCC), 23 patients with previous cutaneous malignant melanoma (MM), and 32 healthy controls. Measurements were performed on UV-exposed (forehead, upper back) and UV non-exposed (buttock) skin. No significant differences in pigmentation percentage, total UCA concentration, relative (%) or absolute (nmol/cm2) cis-UCA concentration were observed between the groups in any of the body sites studied. The net production of cis-UCA after irradiation with a single test UV dose was evaluated. The relative production of cis-UCA following irradiation was significantly higher in both cancer groups when compared with the control group, while no significant difference was found between the BCC and the MM patients.     

Cytosolic enzymes with a mitochondrial ancestry from the anaerobic chytrid Piromyces sp. E2

The anaerobic chytrid Piromyces sp. E2 lacks mitochondria, but contains hydrogen-producing organelles, the hydrogenosomes. We are interested in how the adaptation to anaerobiosis influenced enzyme compartmentalization in this organism. Random sequencing of a cDNA library from Piromyces sp. E2 resulted in the isolation of cDNAs encoding malate dehydrogenase, aconitase and acetohydroxyacid reductoisomerase. Phylogenetic analysis of the deduced amino acid sequences revealed that they are closely related to their mitochondrial homologues from aerobic eukaryotes. However, the deduced sequences lack N-terminal extensions, which function as mitochondrial leader sequences in the corresponding mitochondrial enzymes from aerobic eukaryotes. Subcellular fractionation and enzyme assays confirmed that the corresponding enzymes are located in the cytosol. As anaerobic chytrids evolved from aerobic, mitochondria-bearing ancestors, we suggest that, in the course of the adaptation from an aerobic to an anaerobic lifestyle, mitochondrial enzymes were retargeted to the cytosol with the concomitant loss of their N-terminal leader sequences.     

What a long, strange trip it''s been [with apologies to Jerry Garcia!

The possibility of obtaining antibodies to human hemoglobin and erythrocytes and their use for the detection of hidden blood in different biological fluids was studied. The test system, based on the reaction of coagglutination with the use of protein A of Staphylococcus aureus Cowan 1 and magnetic sorbent, is proposed.     

The effect of dexamethasone treatment on the expression of the regulatory genes of ketogenesis in intestine and liver of suckling rats

The influence of the injection of dexamethasone on ketogenesis in 12 day old suckling rats was studied in intestine and liver by determining mRNA levels and enzyme activity of the two genes responsible for regulation of ketogenesis: carnitine palmitoyl transferase I (CPT I) and mitochondrial HMG-CoA synthase. Dexamethasone produced a 2 fold increase in mRNA and activity of CPT I in intestine, but led to a decrease in mit. HMG-CoA synthase. In liver the mRNA levels and activity of both CPT I and mit. HMG-CoA synthase decreased. Comparison of these values with the ketogenic rate of both tissues following dexamethasone treatment suggests that mit. HMG-CoA synthase could be the main gene responsible for the regulation of ketogenesis in suckling rats. The changes produced in serum ketone bodies by dexamethasone, with a profile that is more similar to the ketogenic rate in the liver than that in the intestine, indicate that liver contributes more to ketone body synthesis in suckling rats. Two day treatment with dexamethasone produced no change in mRNA or activity levels for CPT I in liver or intestine. While mRNA levels for mit. HMG-CoA synthase changed little, the enzyme activity is decreased in both tissues.