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It has been reported that C-nitration of proteins occurs under nitrative/oxidative stress; however, its role in pathophysiological situations is not fully understood. In this study, we determined that nitration of Tyr(345) and Tyr(368) in the beta-subunit of the mitochondrial F(o)F(1)-ATPase is a major target for nitrative stress in rat liver under in vivo conditions. The chemical characteristics of these Tyr make them suitable for a facilitated nitration (solvent accessibility, consensus sequence, and pK(a)). Moreover, beta-subunit nitration increased significantly with the age of the rats (from 4 to 80 weeks old) and correlated with decreased ATP hydrolysis and synthesis rates. Although its affinity for ATP binding was unchanged, maximal ATPase activity decreased between young and old rats by a factor of two. These changes directly impacted the available ATP concentration in vivo, and it was expected that they would affect multiple cellular ATP-dependent processes. For instance, at least 50% of available [ATP] in the liver of older rats would have to be committed to sustain maximal Na(+)-K(+)-ATPase activity, whereas only 30% would be required for young rats. If this requirement was not fulfilled, the osmoregulation and Na(+)-nutrient cotransport in liver of older rats would be compromised. On the basis of our studies, we propose that targeted nitration of the beta-subunit is an early marker for nitrative stress and aging.

A spectro-polarimetric method is presented to allow the recovery of the frequency dependent polarization modulation function for an achromatic half-wave plate. We show how the non ideal nature of the modulator can be characterized for removal of both instrument effects and variations related to the source spectral index.

Chronic multi-drug resistant Pseudomonas aeruginosa infections among hospitalized elderly patients are nearly epidemic in some institutions and biofilms are now recognized as the root cause of such chronic infections such as with cystic fibrosis patients. We address the potential risks and advantages of combining commonly prescribed calcium channel blockers (CCBs) with the fluoroquinolone levofloxacin in the treatment of P. aeruginosa biofilms by using in vitro real-time monitoring of biofilm growth/inhibition over time. while mibefradil and diltiazem appear to be strongly antagonistic toward antimicrobial activity of levofloxacin, amlodipine and bepridil appear to have significant synergistic effects.

A metal-mesh achromatic half-wave plate (HWP) has been designed, manufactured, and tested for potential use in millimeter and submillimeter astronomical instruments. The prototype device presented here is based on a 12-grid Shatrow [IEEE Trans. Antennas Propag. 43, 109 (1995)] recipe to operate over the frequency range of 120-180 GHz. Transmission line modeling and finite-element analysis [Ansoft HFSS website: http://www.ansoft.com/hfss/] were used to optimize the design geometrical parameters in terms of the device transmission, reflection, absorption, phase-shift, and cross-polarization as a function of frequency. The resulting prototype device was constructed and characterized using incoherent radiation from a polarizing Fourier transform spectrometer to explore its frequency and polarization behavior. These measurements are shown to be in excellent agreement with the models. Lists of the achieved HWP performance characteristics are reported.

We present a simple, inexpensive, and effective method of applying antireflection coatings to zinc selenide windows designed to operate in the thermal infrared wavelength region.

As our aged population increases, infections among elderly residing in long term care facilities will challenge our ability to maintain an effective battery of antibiotics. In this setting, we can predict infection by antibiotic resistant organisms in elderly patients with a history of previous antibiotic treatment and exposure to resistant organisms from multiple hospitalizations. The elderly often acquire infections in tandem with common disease states such as diabetes and heart disease. Polypharmacy increases risk of synergistic and antagonist reactions between pharmaceuticals. Elderly patients may be deficient in their ability to clear drugs from the body due to declining lung, kidney/bladder, gastrointestinal and circulatory efficiency. Accumulation of standard antibiotic doses in the body leads to heightened risk of achieving toxic drug levels and increases the chances of unfavorable interactions with other medications. Optimized dosing strategies must be designed specifically for this population using pharmacodynamic principles that honor the unique circumstances of the elderly. Rational and effective dosing strategies based on pharmacodynamic breakpoints and detailed understanding of the pharmacokinetics of antibiotics in the elderly further the goal of achieving complete eradication of an infection in a timely manner, prevent selection of drug resistant bacteria and minimize toxic effects in elderly patients. The present article includes information of patents for antibiotic therapy in the elderly.

Throughout most of the world we are witnessing an ever increasing number of aged people as a percentage of the general population. In the coming years, the unique spectrum of infections presented by an elderly population, particularly those in long-term care facilities, will challenge our ability to maintain an effective battery of antibacterials. The pharmacokinetic parameters of most antibacterial agents are altered when assessed in the elderly due in part to non-pathological physiological changes. The inability to clear a drug from the body due to declining lung, kidney/bladder, gastrointestinal and circulatory efficiency can cause accumulation in the body of drugs given in standard dosages. While this may have the potential benefit of achieving therapeutic concentrations at a lower dose, there is also a heightened risk of attaining toxic drug concentrations and an increased chance of unfavourable interactions with other medications. Pharmacodynamic issues in the elderly are related to problems that arise from treating elderly patients who may have a history of previous antibacterial treatment and exposure to resistant organisms from multiple hospitalisations. Furthermore, the elderly often acquire infections in tandem with other common disease states such as diabetes mellitus and heart disease. Thus, it is essential that optimised dosage strategies be designed specifically for this population using pharmacodynamic principles that take into account the unique circumstances of the elderly. Rational and effective dosage and administration strategies based on pharmacodynamic breakpoints and detailed understanding of the pharmacokinetics of antibacterials in the elderly increase the chances of achieving complete eradication of an infection in a timely manner. In addition, this strategy helps prevent selection of drug-resistant bacteria and minimises the toxic effects of antibacterial therapy in the elderly patient.

An achromatic half-wave plate (HWP) to be used in millimeter cosmic microwave background (CMB) polarization experiments has been designed, manufactured, and tested. The design is based on the 5-plates Pancharatnam recipe and it works in the frequency range 85-185 GHz. A model has been used to predict the transmission, reflection, absorption, and phase shift as a function of frequency. The HWP has been tested by using coherent radiation from a back-wave oscillator to investigate its modulation efficiency and with incoherent radiation from a polarizing Fourier transform spectrometer (FTS) to explore its frequency behavior. The FTS measurements have been fitted with an optical performance model which is in excellent agreement with the data. A detailed analysis of the data also allows a precise determination of the HWP fast and slow axes in the frequency band of operation. A list of the HWP performance characteristics is reported including estimates of its cross polarization.

Studies with isolated mitochondria are performed at artificially high pO(2) (220 to 250 microM oxygen), although this condition is hyperoxic for these organelles. It was the aim of this study to evaluate the effect of hypoxia (20-30 microM) on the calcium-dependent activation of 2-oxoglutarate dehydrogenase (or 2-ketoglutarate dehydrogenase; OGDH) and mitochondrial nitric-oxide synthase (mtNOS). Mitochondria had a P/O value 15% higher in hypoxia than that in normoxia, indicating that oxidative phosphorylation and electron transfer were more efficiently coupled, whereas the intramitochondrial free calcium concentrations were higher (2-3-fold) at lower pO(2). These increases were abrogated by ruthenium red indicating that the higher uptake via the calcium uniporter was involved in this process. Mitochondria at high calcium concentration microdomains may produce nitric oxide, given the K(0.5) of calcium for OGDH (0.16 microM) and mtNOS (approximately 1 microM). Nitric oxide, by binding to cytochrome oxidase in competition with oxygen, decreases the rate of oxygen consumption. This condition is highly beneficial for the following reasons: i, these mitochondria are still able to produce ATP and support calcium clearance; ii, it prevents the accumulation of ROS by slowing the rate of oxygen consumption (hence ROS production); iii, the onset of anoxia is delayed, allowing oxygen to diffuse back to these sites, thereby ameliorating the oxygen gradient between regions of high and low calcium concentration. In this way, oxygen depletion at the latter sites is prevented. This, in turn, assures continued aerobic metabolism which may involve the activated dehydrogenases.

Nitric oxide is generated in vivo by nitric-oxide synthase (NOS) during the conversion of L-Arg to citrulline. Using a variety of biological systems and approaches emerging evidence has been accumulated for the occurrence of a mitochondrial NOS (mtNOS), identified as the alpha isoform of neuronal or NOS-1. Under physiological conditions, the production of nitric oxide by mitochondria has an important implication for the maintenance of the cellular metabolism, i.e. modulates the oxygen consumption of the organelles through the competitive (with oxygen) and reversible inhibition of cytochrome c oxidase. The transient inhibition suits the continuously changing energy and oxygen requirements of the tissue; it is a short-term regulation with profound pathophysiological consequences. This review describes the identification of mtNOS and the role of posttranslational modifications on mtNOS' activity and regulation.

An apparent discrepancy arises about the role of calcium on the rates of oxygen consumption by mitochondria: mitochondrial calcium increases the rate of oxygen consumption because of the activation of calcium-activated dehydrogenases, and by activating mitochondrial nitric oxide synthase (mtNOS), decreases the rates of oxygen consumption because nitric oxide is a competitive inhibitor of cytochrome oxidase. To this end, the rates of oxygen consumption and nitric oxide production were followed in isolated rat liver mitochondria in the presence of either L-Arg (to sustain a mtNOS activity) or N(G)-monomethyl-L-Arg (NMMA, a competitive inhibitor of mtNOS) under State 3 conditions. In the presence of NMMA, the rates of State 3 oxygen consumption exhibited a K(0.5) of 0.16 microM intramitochondrial free calcium, agreeing with those required for the activation of the Krebs cycle. By plotting the difference between the rates of oxygen consumption in State 3 with L-Arg and with NMMA at various calcium concentrations, a K(0.5) of 1.2 microM intramitochondrial free calcium was obtained, similar to the K(0.5) (0.9 microM) of the dependence of the rate of nitric oxide production on calcium concentrations. The activation of dehydrogenases, followed by the activation of mtNOS, would lead to the modulation of the Krebs cycle activity by the modulation of nitric oxide on the respiratory rates. This would ensue in changes in the NADH/NAD and ATP/ADP ratios, which would influence the rate of the cycle and the oxygen diffusion.

The goal of this study was to explore the occurrence of nitrated proteins in mitochondria given that these organelles are endowed with a mitochondrial nitric oxide (NO.-) synthase and considering the important role that mitochondria have in energy metabolism. Our hypothesis is that nitration of proteins constitutes a posttranslational modification by which NO.- exhibits long-term effects above and beyond those bioregulatory ones mediated through the interaction with cytochrome c oxidase. Our studies are aimed at understanding the mechanisms underlying the nitration of proteins in mitochondria and the biological significance of such a process in the cellular milieu. On promoting a sustained NO.- production by mitochondria, we investigated various aspects of protein nitration. Among them, the localization of nitrated proteins in mitochondrial subfractions, the identification of nitrated proteins through proteomic approaches, the characterization of affected pathways, and depiction of a target sequence. The biological relevance was analyzed by considering the turnover of native and nitrated proteins. In this regard, mitochondrial dysfunction, ensuing nitrative stress, may be envisioned as the result of accumulation of nitrated proteins, resulting from an overproduction of endogenous NO.- (this study), a failure in the proteolytic system to catabolize modified proteins, or a combination of both. Finally, this study allows one to gain understanding on the mechanism and nitrating species underlying mitochondrial protein nitration.

The biochemistry of the mitochondrial production of nitric oxide is reviewed to gain insight into the basic role of this radical in mitochondrial and cellular oxidative metabolism. The mitochondrial production of nitric oxide is catalyzed by a nitric-oxide synthase (mtNOS). This enzyme has the same cofactor and substrate requirements as other constitutive nitric-oxide synthases. Its occurrence was demonstrated in various mitochondrial preparations from different organs and species using diverse approaches (oxidation of oxymyoglobin, electron paramagnetic resonance in conjunction with spin trap, radiolabeled L-arginine, immunohistochemistry, nitric-oxide electrode). MtNOS has been identified as the alpha isoform of nNOS, acylated at a Thr or Ser residue, and phosphorylated at the C-terminal end. Endogenous nitric oxide reversibly inhibits oxygen consumption and ATP synthesis by competitive inhibition of cytochrome oxidase. Nitric oxide is the first molecule that fulfills the requirement for a cytochrome oxidase activity modulator: it is a competitive inhibitor, produced endogenously at a fair rate near the target site, at concentrations high enough to exhibit an inhibitory effect on cytochrome oxidase. The role of the mitochondrial nitric oxide production is discussed in terms of the physiological (modulating oxygen gradients into tissues) and pathological (abrogation of oxygen gradient modification, apoptosis, protein nitrative/oxidative stress) implications.

Prompt diagnosis of testicular torsion remains difficult. Since warning symptoms occur in one third of patients and salvage rates correspond to the interval between symptom onset and operation, higher salvage rates should be achievable. Separating torsion from epididymitis is complicated by overlapping ages of peak incidence, shared symptoms, and the need for rapid distinction of the two. Doppler studies (88% accuracy) and nuclear scans (95% accuracy) help confirm the diagnosis, but correct technique is essential, and their use should not delay prompt operation. The diagnosis of epididymitis should be made cautiously in persons younger than the age of 35 years.

Two studies examined children's increasing ability to analyze tasks in terms of the perceptual features that affect task difficulty. Of particular interest was any understanding that perceptual confusions occur during the search for an object surrounded by objects similar in shape or color to that object. In Study 1, 32 pre-schoolers constructed arrays intended to make the search easy or difficult. They made the search difficult simply by putting many toys into the toy box. In a forced-choice situation, they indicated that task difficulty was influenced by the number of objects and the similarity in color and shape of the targets and the surrounding objects. Study 2 more thoroughly examined knowledge of color and shape confusions, using 96 children from Grades K, 1, 3, and 4, assigned to two age groups. The older children but not the younger ones showed a significant understanding of color and shape confusions. Both age groups understood that performance is affected by a person's interest level and degree of attention to the task. The results were discussed in terms of the accessibility of the children's knowledge under different conditions.

We report 3 cases in which the testicle was untwisted inadequately or torsion recurred soon after manipulative detorsion. While manipulative detorsion can decrease ischemia time an operation should follow as soon as possible to confirm detorsion, assure orchiopexy and prevent repetitive episodes.