Silver cycles: The stocks and flows project, part 3

The quantitative assessment of the flows of materials from resource extraction to final disposal informs resource policy, energy planning, environmental science, and waste management. This article reports the technological cycles of silver worldwide and in representative countries for 1997. Most silver is produced in conjunction with other metals; only a quarter of world production is from silver ore. Industrial applications account for 40% of silver use. While about a third of world use goes into jewelry, tableware, and the arts, silver cycles through the world economy to recycling faster than metals such as copper and zinc. Despite decreasing use in photography, demand for silver continues to increase.     

Predicting odorant quality perceptions from multidimensional scaling of olfactory bulb glomerular activity patterns.

Odorants and their perceptions differ along multiple dimensions, requiring that a critical examination of any putative neural code directly assess the multidimensional nature of the encoding process. Previous work has examined simple, systematic odorant differences that, regardless of coding strategy, would be expected to produce simple, systematic predictions in neural and behavioral responses. In the present study, an odorant identification confusion matrix task that extracts precise quality relationships across odorants was used to determine whether spatially specific glomerular activity patterns predict perceptual quality relationships for odorants that cannot easily be classified a priori along a single chemical dimension. Multidimensional scaling (MDS) analysis of odorant pattern similarity measures derived from the comparison of [14C]-2-deoxyglucose glomerular activity pattern data yielded a two-dimensional odorant activity space that was highly significantly predictive of similarly obtained odorant perceptual spaces, uniformly across animals. These results strongly support the relevance of global spatial patterns in the olfactory bulb to the encoding of odor quality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Disposition of aerosolized liposomal amphotericin B

Amphotericin B (AmB) is an important drug for the treatment of fungal infection, but toxicity limits the lung tissue doses which may be achieved through intravenous administration. Although incorporation of AmB in liposomes reduces these effects and increases the therapeutic index for intravenous administration, targeted delivery to lung tissues via inhaled liposomal AmB aerosol may be a more effective approach. Aerosolization of liposomal amphotericin B targets the lungs, the organs first infested by many fungi. Development of optimal aerosolized liposomal AmB therapies requires a better understanding of the effect that liposome surface charge has on lung clearance kinetics. In this work we evaluated the clearance kinetics and organ distribution of inhaled liposomal AmB in male Balb/C mice. Mice were exposed via nose only to AmB-containing liposomal aerosols having positive, negative, or neutral surface charge characteristics. The formulations were aerosolized using a Collison nebulizer. Groups of animals were euthanized at predetermined times and the lungs and other organs were analyzed for AmB. AmB was not detected in serum and other organs such as kidneys, liver, and brain. The disposition of neutral and positive liposomal amphotericin B in lungs followed biexponential kinetics. The alpha and beta phase half-lives for positive liposomes were 1.3 and 15.1 days, respectively, and 2.3 and 22 days for neutral liposomes. AmB delivered via negative liposomes exhibited monoexponential clearance with a half-life of 4.5 days. These results suggest that toxic side effects in nontarget tissues are minimal and may indicate a potential for long term protection against fungal infections.     

Elevated platelet factor 4 and beta-thromboglobulin plasma levels in depressed patients with ischemic heart disease

Clinical depression has recently been recognized as an independent risk factor for cardiac mortality in patients after myocardial infarction. The underlying mechanisms of this increased mortality remain unclear. This study investigated the hypothesis that patients suffering from ischemic heart disease (IHD) and depression concurrently may have abnormal platelet activation resulting in an increased risk of thrombosis. Platelet factor 4 (PF4) and beta-thromboglobulin (beta-TG) were measured in young healthy control subjects, in nondepressed patients with IHD, and in depressed patients with IHD. Mean PF4 and beta-TG plasma levels in the IHD group with depression were found to be significantly higher than those of the control and IHD groups. This increase was not related to age, gender, racial difference, aspirin use, or severity of cardiac disease. This finding suggests that in depressed patients with IHD there is greater platelet activation, and may indicate an increased risk of thrombotic complications.     

Functional differences among the six Saccharomyces cerevisiae tRNATrp genes

The Saccharomyces cerevisiae haploid genome includes six copies of the gene encoding tRNATrp which are scattered on five chromosomes. Other, non-functional tDNATrp fragments also occur in the genome. The segments of all six genes which encode the 72-nucleotide mature tRNATrp, as well as a 34-nucleotide intervening sequence, are identical. However, the 5' and 3' flanking sequences diverge virtually at the boundaries of the coding region. We have used an assay based on suppression of UGA mutations by multi-copy clones of tDNATrp to search for functional differences among these genes. Previous studies with one tDNATrp had demonstrated that moderate suppression of a UGA mutation, leu2-2, resulted from introduction of a multi-copy clone of the gene. Attempts to use this assay to select tDNATrp clones from a yeast genomic library yielded only four of the six different clones. The other two genes were amplified by PCR and cloned in pRS202, a 2 mu vector also used for the genomic library. Plasmids bearing the six tRNA genes were transformed into S. cerevisiae strain JG369.3B and scored for their ability to suppress the leu2-2 mutation as well as his4-260, another UGA marker. Two of the six tRNATrp clones were unable to suppress either marker, two evidenced weak suppression of the Leu auxotrophy, and two were able to suppress both markers. Growth rates in liquid media requiring suppression were measured for cell lines carrying each of the clones. Differences greater than 50-fold were observed in media lacking histidine. An evolutionary tree based on 5'-flanking sequence corresponds reasonably well with suppressor activity, while a similar analysis of 3'-flanking sequence does not. This suggests that the functional differences are based on divergence in the 5'-flanking sequences of the tRNATrp genes.     

Surgical management of ventricular tachycardia

BACKGROUND: Ventricular tachyarrhythmias are the leading cause of death from coronary artery disease. A small percentage of these arrhythmias originate in chronically ischemic myocardium, rather than acutely ischemic myocardium, and can be refractory to medical management. Epicardial mapping and focal cryoablation of foci demonstrating early activation may provide definitive therapy when pharmacologic management fails. We report a series of 42 consecutive patients with refractory ventricular tachycardia (VT) who were treated with open epicardial mapping and focal cryoablation after pharmacologic management failed. METHODS: We retrospectively reviewed the records of patients who underwent surgical treatment of malignant VT. For patients not recently seen in the clinic, we conducted telephone interviews. At the time of operation, epicardial mapping was performed to locate foci of early electrical activation. These foci were then cryoablated, using 2-minute applications of liquid nitrogen-cooled probes. All patients underwent postoperative electrophysiologic studies to test for inducible VT. RESULTS: Of these 42 patients, 34 (81%) were male, 8 (19%) female. Average age was 62.9 +/- 10.6 years; ejection fraction, 0.20 (range, 0.04 to 0.50); and number of foci ablated, 2.1 +/- 1.1 (range, 1 to 6). At the time of cryoablation, all patients underwent additional procedures, including aneurysmectomy, coronary artery bypass, or valve replacement. The 30-day operative mortality was 9.5% (4 of 42). Of the 38 survivors, 36 (94.7%) were clinically free of VT; the remaining 2 had spontaneous or inducible VT. CONCLUSIONS: Open cryoablation of foci propagating VT appears to be safe and effective. It may be the most definitive treatment for malignant VT.     

Oropharyngeal candidiasis in patients with AIDS: randomized comparison of fluconazole versus nystatin oral suspensions

A total of 167 human immunodeficiency virus (HIV)-infected patients with oropharyngeal candidiasis were randomly assigned to receive 14 days of therapy with liquid suspension fluconazole (100 mg once daily) or liquid nystatin (500,000 U four times daily). At day 14, 87% of the fluconazole-treated patients were clinically cured, as opposed to 52% in the nystatin-treated group (P < .001). Fluconazole eradicated Candida organisms from the oral flora in 60%, vs. a 6% eradication rate with nystatin (P < .001). The fluconazole group had fewer relapses noted on day 28 (18%, vs. 44% in the nystatin group; P < .001). This relapse difference no longer existed by day 42. Fluconazole oral suspension as a systemic therapy was more effective than liquid nystatin as a topical therapy in the treatment of oral candidiasis in HIV-infected patients and provided a longer disease-free interval before relapse.     

Developments in the fabrication and performance of high-quality HgCdTe detectors grown on 4-in. Si substrates

We are continuing to develop our growth and processing capabilities for HgCdTe grown on 4-in. Si substrates by molecular beam epitaxy (MBE). Both short-wave and mid-wave infrared (SWIR and MWIR) double-layer hetero-junctions (DLHJs) have been fabricated. In order to improve the producibility of the material, we have implemented an in-situ growth composition-control system. We have explored dry etching the HgCdTe/Si wafers and seen promising results. No induced damage was observed in these samples. Detector results show that the HgCdTe/Si devices are state-of-the-art, following the diffusion-limited trend line established by other HgCdTe technologies. Focal-plane array (FPA) testing has been performed in order to assess the material over large areas. The FPA configurations range from 128×128 to 1,024×1,024, with unit cells as small as 20 μm. The MWIR responsivity and NEDT values are comparable to those of existing InSb FPAs. Pixel operabilities well in excess of 99% have been measured. We have also explored the role of growth macrodefects on diode performance and related their impact to FPA operability. The SWIR HgCdTe/Si shows similar results to the MWIR material. Short-wave IR FPA, median dark-current values of less than 0.1 e⁻/sec have been achieved.     

The placental transfer of sufentanil: effects of fetal pH, protein binding, and sufentanil concentration

This study investigated factors that influence the placental transfer of sufentanil using the dual-perfused, single-cotyledon human placental model. Placentas were collected from healthy women. Experiments were designed to elucidate the effects of maternal protein binding, changing maternal sufentanil concentration (1, 10, 20, and 100 ng/mL) and decreasing fetal pH (fetal acidemia 7.2, 7.0, 6.8) on the placental transfer of sufentanil. Sufentanil crossed the placenta rapidly at a rate two-thirds that of the transfer marker, antipyrine. Sufentanil transfer increased linearly with the maternal concentration (r = 0.999). Sufentanil/antipyrine maternal to fetal (M-->F) transfer ratios were significantly reduced (0.66 +/- 0.05 vs 0.40 +/- 0.04, P < 0.05) when fresh frozen plasma was added to the maternal circuit to enhance protein binding. Fetal pH and sufentanil transfer were related because sufentanil M-->F clearance increased significantly as the fetal pH decreased (r = 0.973, P < 0.05). Sufentanil appears to cross the placenta by passive diffusion but is modulated by the degree of maternal protein binding. Sufentanil M-->F transfer is enhanced by fetal acidemia.     

Modeling the cross-sectional relationships between religion, physical health, social support, and depressive symptoms

The authors examined models of the relationships between religious activities, physical health, social support, and depressive symptoms in a sample of 4,000 persons age 65 and over. Religious activity was examined first as a single composite construct and then split into three component variables that were examined individually. Religious activity as a single construct was correlated with both social support and good physical health but was unrelated to depression. Split into the three components, model fit was significantly increased. Frequency of church attendance was positively related to physical health and negatively related to depression, but was surprisingly unrelated to social support. Frequent churchgoers were about half as likely to be depressed. Private prayer/Bible reading was negatively correlated with physical health and positively correlated with social support, but unrelated to depression. Religious TV/radio listening was unrelated to social support, negatively related to good physical health, and, unexpectedly, positively associated with depression.