Radiation effects on a lithium tantalate optical waveguide structure

The effects of X- and gamma radiation on an optical waveguide, fabricated in lithium tantalate, are described and discussed. The measurements indicate that quite severe radiation environments would be necessary to produce significant problems with LiTaO/sub 3/ devices. However, the level of the radiation effects may depend, like those in semiconductor devices and fibre optics, on the details of the composition of the material and the constructional methods employed. Because there appear to be effects due to a radiation-induced, internal, electric field, there will be a dependence on the cut of the crystal used.<>     

Single-exposure conventional and computed radiography. The hybrid cassette revisited

RATIONALE AND OBJECTIVES: The authors constructed and evaluated a hybrid cassette for single-exposure extremity imaging with storage-phosphor plates and conventional radiographic film. METHODS: A hybrid cassette was constructed using a fine radiographic screen and a storage-phosphor plate. Exposures of a Lucite step wedge and a line pair gauge were made with the hybrid cassette, a conventional radiographic cassette, and a storage-phosphor cassette. The spatial resolution and imaging speeds of the hybrid and standard systems were compared. RESULTS: Spatial resolution loss was less than 0.5 line pairs per mm with the hybrid cassette. Speed loss was characteristic of the hybrid cassette, requiring approximately 40% greater exposure to produce the same film density as standard cassettes. CONCLUSIONS: The speed difference between this and a previous study is probably due to differences in film-screen choice, kilovolt peak, and storage-phosphor plate generations. The sensitivity spectrum of our film and the emission spectrum of our screens were more closely matched than were the spectra in the previous study; we used lower kilovolt peak, and our storage-phosphor plates were a later, more efficient, generation. Despite slight speed losses, the hybrid cassette appears to be a better choice for obtaining matched images for clinical trials than the alternative of two separate exposures.     

Oral teratoma (epignathus) with intracranial extension: a report of two cases

Epignathi are unusual congenital tumours presenting as oropharyngeal masses, often resulting in rapid asphyxia following birth. Occasionally, intracranial extension of the tumour is present, and two such cases are described. The presence of this complication, diagnosable by ultrasound examination, indicates that aggressive surgical treatment is inappropriate.     

Synthesis and binding properties of MK-801 isothiocyanates; (+)-3-isothiocyanato-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten- 5,10-imine hydrochloride: a new, potent and selective electrophilic affinity ligand for the NMDA receptor-coupled phencyclidine binding site

Three new site-directed irreversible (wash-resistant) ligands for the high-affinity phencyclidine (PCP) binding site associated with the N-methyl-D-aspartate (NMDA) receptor were synthesized and their binding characteristics were studied. (+)-3- And (+)-2-isothiocyanato-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cycl ohepten-5,10 - imine hydrochloride ((+)-8a,b.HCl) were prepared in four steps from the corresponding nitro derivatives (+)-4a,b, which were obtained by nitration of (+)-3 (MK-801). In the same way the optical antipode (-)-8a.HCl was synthesized from (-)-3. At a concentration of 100 nM, the 3-isothiocyanate derivative (+)-8a irreversibly labeled approximately 50% of the (+)-[3H]-3 binding sites, compared to 20 microM needed for its optical antipode (-)-8a and the 2-isothiocyanate (+)-8b. The apparent Ki values for reversible inhibition of (+)-[3H]-3 binding by (+)- and (-)-8a and (+)-8b were 37,838, and 843 nM, respectively. In contrast, metaphit (1b) and etoxadrol m-isothiocyanate (2b), two previously reported irreversible ligands for the PCP binding site, label about 50% of the (+)-[3H]-3 binding sites at 100 microM and 250 nM, respectively, with apparent Ki values for reversible inhibition of 535 and 94 nM. Compound (+)-8a is also a selective affinity ligand, displaying little or no irreversible in vitro affinity at 100 microM for opioid, benzodiazepine, muscarinic, and dopamine receptors. At a 25 microM concentration, (+)-8a caused an irreversible 52% reduction of binding to sigma 1-receptors. Compound (+)-8a is the most potent known electrophilic affinity label for the PCP binding site. Its potency and selectivity should enable it to be a valuable tool for the elucidation of the structure and function of the NMDA receptor-associated PCP binding site in the mammalian central nervous system.     

Peroxisome proliferator-activated receptor-gamma agonist, rosiglitazone, protects against nephropathy and pancreatic islet abnormalities in Zucker fatty rats

Rosiglitazone (BRL 49653), a peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonist and potent insulin action-enhancing agent, was given in the diet (50 micromol/kg of diet) to male Zucker rats ages 6-7 weeks for 9 months (prevention group). In this treatment mode, rosiglitazone prolonged the time to onset of proteinuria from 3 to 6 months and markedly reduced the rate of its subsequent progression. Progression was also retarded when treatment was commenced (intervention group) after proteinuria had become established (4 months; ages 24-25 weeks). In either treatment mode, rosiglitazone normalized urinary N-acetyl-beta-D-glucosaminidase activity, a marker for renal proximal tubular damage, and ameliorated the rise in systolic blood pressure that occurred coincidentally with the development of proteinuria in Zucker fatty control rats. The renal protective action of rosiglitazone was verified morphologically. Thus in the prevention group there was an absence of the various indexes of chronic nephropathy that were prominent in the Zucker fatty control group, namely, glomerulosclerosis, dilated tubules containing proteinaceous casts, a loss of functional microvilli on the tubular epithelium, and varying degrees of chronic interstitial nephritis. An intermediate pathology was observed in the intervention group. Also, pancreatic islet hyperplasia, ultrastructural evidence of beta-cell work hypertrophy, and derangement of alpha-cell distribution within the islet were prominent features of Zucker fatty control rats, but these adaptive changes were ameliorated (intervention group) or prevented (prevention group) by rosiglitazone treatment. These data demonstrate that treatment of Zucker fatty rats with rosiglitazone produced substantial protection over a prolonged period against the development and progression of renal injury and the adaptive changes to pancreatic islet morphology caused by sustained hyperinsulinemia.     

Development of a high-efficiency method for gene marking of Dunning prostate cancer cell lines with the enzyme beta-galactosidase

Most peripheral artery disease is of ischemic atherosclerotic etiology and manifested as intermittent claudication (IC). Death and disability from atherosclerotic cardiovascular disease (CVD) is a growing problem because of the rapidly increasing elderly segment of the population. By the year 2015 the elderly will constitute 14.8% of Americans. Of the total 255 million, 13.8 million are over age 75 years and 9 million are women. On reaching age 65 years, the average remaining lifetime is 17.4 years. In the USA this 11% of the population accounts for 29% of the health costs and 70% of all deaths are attributable to cardiovascular disease. About 9.6% of cardiovascular events are due to peripheral artery disease manifested as IC requiring 777,000 office visits and 63,000 hospitalizations. Also, 17,400 deaths each year are attributed directly to this cause. The biennial incidence of IC in the Framingham Study was 7.1 per 1000 for men and 3.6% for women, increasing with age in both sexes up to age 75 years. At all ages there is a distinct male predominance. In the 35-64-year age range IC incidence is virtually identical to that of cardiac failure and stroke, but only one-third of CHD incidence. Beyond age 65 years IC incidence is only half that of other atherosclerotic cardiovascular conditions. The incidence of carotid bruits and non-palpable pedal pulses is virtually identical in the two sexes; only femoral bruits are male predominant. At time of diagnosis of IC one in three already have overt evidence of CHD, stroke or congestive heart failure (CHF). In those free of these at outset CHD and strokes occur at two to three times the general population rate and CHF 3.5-4.5 times the rate of persons without IC. Within 10 years of IC onset 43% develop CHD, 21% strokes and 24% cardiac failure. Carotid and femoral bruits are likewise harbingers of other atherosclerotic CVD. As many as 45% of IC victims lose their symptoms for extended periods. Survival following onset of IC is only two-thirds of that general population; after 10 years 60% died. This high mortality is largely attributable to coexistent cardiovascular impairments. A risk profile comprising the major cardiovascular risk factors predicts occurrence of IC even better than CHD. IC risk increases progressively with burden of the risk factors. With an aging population of increased size peripheral artery disease is a problem of increasing dimensions. Attention to comorbid conditions is essential if survival is to be improved. Because IC shares many of the same risk factors, measures to prevent CHD, CHF and strokes should also reduce IC risk.