Electrochemical behaviour of chalcopyrite in the presence of silver and Sulfolobus bacteria

The electrochemical behaviour of massive chalcopyrite electrodes has been studied in an acid medium (pH1.5) containing silver ions (0.02gdm?3Ag+) and thermophilic bacteria (68°C). Preliminary tests on particulate electrodes made from graphite, elemental sulfur and Ag2S were included to determine the electrochemical response of reactants (Ag+) and products (S° and Ag2S) associated with the dissolution of chalcopyrite in the presence of silver. Massive chalcopyrite electrodes under potential scan showed a dependence on the dissolution of the Ag2S film with both the time of contact with the silver solution and [Ag+]. As well as Ag2S, metallic silver was detected on the chalcopyrite surface. It has been demonstrated that Fe3+ and bacteria play an important role in the regeneration of the Ag2S film. The breakdown of this film is a requirement for the further dissolution of chalcopyrite. The bioleaching of chalcopyrite with thermophilic microorganisms in the presence of silver decreased the decomposition potential of the electrode and favoured its electrodissolution. Bioleaching treatment in the presence of silver ions for periods of time longer than two weeks did not improve the surface reactivity. However, in the initial stages of the process, the lower reactivity of the bioleached electrodes was probably related to a toxic effect of silver on the microorganisms.     

Operative management of adrenal metastases from lung carcinoma

Most surgeons consider patients with solitary adrenal metastasis from a primary lung carcinoma incurable and avoid excision of both the adrenal and primary lung tumors. However, several cases of successful surgical management of these patients recently have been reported. We reviewed 12 surgically treated patients with isolated adrenal and lung disease and identified 2 survivors of greater than fifteen years (17%) and 4 additional patients who are still alive following combined resection (34%). This survival rate, albeit in a selected population, represents an improvement over the natural history of nine months' survival. We suggest that if after six to twelve months of following patients with lung cancer and isolated adrenal metastasis no other evidence of spread of disease is evident, the tumor biology may be favorable and resection of both adrenal and lung lesions is reasonable.     

Restoration of the cAMP second messenger pathway enhances cardiac preservation for transplantation in a heterotopic rat model

Current organ preservation strategies subject graft vasculature to severe hypoxia (PO2 approximately 20 Torr), potentially compromising vascular function and limiting successful transplantation. Previous work has shown that cAMP modulates endothelial cell (EC) antithrombogenicity, barrier function, and leukocyte/EC interactions, and that hypoxia suppresses EC cAMP levels. To explore the possible benefits of cAMP analogs/agonists in organ preservation, we used a rat heterotopic cardiac transplant model; dibutyryl cAMP added to preservation solutions was associated with a time- and dose-dependent increase in the duration of cold storage associated with successful graft function. Preservation was also enhanced by 8-bromo-cAMP, the Sp isomer of adenosine 3',5'monophosphorothioate, and types III (indolidan) and IV (rolipram) phosphodiesterase inhibitors. Neither butyrate alone nor 8-bromoadenosine were effective, and the cAMP-dependent protein kinase antagonist Rp isomer of adenosine 3',5'monophosphorothioate prevented preservation enhancement induced by 8-bromo-cAMP. Grafts stored with dibutyryl cAMP demonstrated a 5.5-fold increase in blood flow and a 3.2-fold decreased neutrophil infiltration after transplantation. To explore the role of cAMP in another cell type critical for vascular homeostasis, vascular smooth muscle cells were subjected to hypoxia, causing a time-dependent decline in cAMP levels. Although adenylate cyclase activity was unchanged, diminished oxygen tensions were associated with enhanced phosphodiesterase activity (59 and 30% increase in soluble types III and IV activity, respectively). These data suggest that hypoxia or graft ischemia disrupt vascular homeostasis, at least in part, by perturbing the cAMP second messenger pathway. Supplementation of this pathway provides a new approach for enhancing cardiac preservation, promoting myocardial function, and maintaining vascular homeostatic properties.     

Serum levels of tumor necrosis factor in squamous cell carcinoma of the head and neck

Two experiments were conducted to study the effect(s) of Borrelia burgdorferi and its metabolites (toxicants?) on canine spermatozoa, using B burgdorferi type strain B-31 and ejaculates from 5 sexually mature dogs. In Experiment 1 the spirochetes were cocultured with semen and incubated under various conditions, and in Experiment 2 the spirochetes were sonicated to release the metabolites/toxicants. The sonicate was then cultured with the semen. The parameters investigated were kinematics and percentage of sperm motility, morphology, and sperm response to the hypoosmotic swelling test and acrosome reaction. There were no visible physical interaction between either dead or motile spirochetes and viable or dead spermatozoa. Neither the spirochetes per se nor their metabolites/toxicants had any significant adverse effect on the functional and morphological characteristics of the canine spermatozoa. It is possible that the exposure times for incubation were not long enough for metabolites or toxicants in the sonicate to significantly affect sperm characteristics. Some investigators have reported that B burgdorferi contain biologically active LPS-like endotoxins. It is also likely that storage denatures B burgdorferi metabolites and other intracellular products in the sonicate and, thus, negates any effects the medium or the sonicate might have on the spermatozoa. The apparent lack of effect suggests that either peripheral metabolism or action on other organ(s) may be required for deleterious action of the spirochetes and/or their toxicants on spermatozoa. It was concluded that B burgdorferi and/or metabolites/toxicants do not have any significant deleterious effects on the functional and morphological characteristics of the postspermatogenic spermatozoa. Interaction of the spirochetes with in vivo conditions may be needed to adversely affect spermatozoa.     

Dynamic scheduling of production-assembly networks in a distributed environment

In complex manufacturing environments, meeting the due dates of the jobs and minimizing in process inventories are important performance metrics. One of the common characteristics of complex production systems is production-assembly network of operations. This paper presents an auction-based algorithm for simultaneous scheduling of all manufactured and assembled jobs in a dynamic environment, where the objective function is to minimize both the due date penalties associated with the final products and the inventory cost of the work in process. An auction-based approach using a Mixed-Integer Linear Programming (MILP) model to construct and evaluate the bids so that the auction mechanism mimics a Lagrangian relaxation-based subgradient optimization to ensure global optimality is proposed. The inner structure of the problem enables very efficient calculation of bids for each job or assembly. Using a full factorial experimental design the properties of the proposed algorithm are analyzed. Results show that the proposed auction based algorithm performs better than the popular dispatching rules and is more scalable than the MILP model or direct implementations of the subgradient algorithm. Furthermore, the proposed algorithm is designed to work in a dynamic environment.     

SNAP-Tag-Targeted MRI-Fluorescent Multimodal Probes

Magnetic resonance imaging (MRI) is a powerful imaging modality, widely employed in research and clinical settings. However, MRI images suffer from low signals and a lack of target specificity. We aimed to develop a multimodal imaging probe to detect targeted cells by MRI and fluorescence microscopy. We synthesized a trifunctional imaging probe consisting of a SNAP-tag substrate for irreversible and specific labelling of cells, cyanine dyes for bright fluorescence, and a chelated Gd^III molecule for enhancing MRI contrast. Our probes exhibit specific and efficient labelling of genetically defined cells (expressing SNAP-tag at their membrane), bright fluorescence and MRI signal. Our synthetic approach provides a versatile platform for the production of multimodal imaging probes, particularly for light microscopy and MRI.