Precambrian non-marine stromatolites in alluvial fan deposits, the Copper Harbor Conglomerate, upper Michigan

Laminated cryptalgal carbonates occur in the Precambrian Copper Harbor Conglomerate of northern Michigan, which was deposited in the Keweenawan Trough, an aborted proto-oceanic rift. This unit is composed of three major facies deposited by braided streams on a large alluvial-fan complex. Coarse clastics were deposited in braided channels, predominantly as longitudinal bars, whereas cross-bedded sandstones were deposited by migrating dunes or linguoid bars. Fine-grained overbank deposits accumulated in abandoned channels. Gypsum moulds and carbonate-filled cracks suggest an arid climate during deposition. Stromatolites interstratified with these clastic facies occur as laterally linked drapes over cobbles, as laterally linked contorted beds in mudstone, as oncolites, and as poorly developed mats in coarse sandstones. Stromatolites also are interbedded with oolitic beds and intraclastic conglomerates. Stromatolitic microstructure consists of alternating detrital and carbonate laminae, and open-space structures. Radial-fibrous calcite fans are superimposed on the laminae. The laminae are interpreted as algal in origin, whereas the origin of the radial fibrous calcite is problematic. The stromatolites are inferred to have grown in lakes which occupied abandoned channels on the fan surface. Standing water on a permeable alluvial fan in an arid climate requires a high water table maintained by high precipitation, or local elevation of the water table, possibly due to the close proximity of a lake. Occurrence of stromatolites in the upper part of the Copper Harbor Conglomerate near the base of the lacustrine Nonesuch Shale suggests that these depositional sites may have been near the Nonesuch Lake.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72022/1/j.1365-3091.1983.tb00713.x.pd

Smart internal stimulus-responsive nanocarriers for drug and gene delivery

The concept of smart drug delivery vehicles involves designing and preparing a nanostructure (or microstructure) that can be loaded with a cargo. This can be a therapeutic drug, a contrast agent for imaging, or a nucleic acid for gene therapy. The nanocarrier serves to protect the cargo from degradation by enzymes in the body, to enhance the solubility of insoluble drugs, to extend the circulation half-life, and to enhance its penetration and accumulation at the target site. Importantly, smart nanocarriers can be designed to be responsive to a specific stimulus, so that the cargo is only released or activated when desired. In this volume we cover smart nanocarriers that respond to internal stimuli that are intrinsic to the target site. These stimuli are specific to the cell type, tissue or organ type, or to the disease state (cancer, infection, inflammation etc). pH-responsive nanostructures can be used for cargo release in acidic endosomal compartments, in the lower pH of tumors, and for specific oral delivery either to the stomach or intestine. Nanocarriers can be designed to be substrates of a wide-range of enzymes that are over-expressed at disease sites. Oxidation and reduction reactions can be taken advantage of in smart nanocarriers by judicious molecular design. Likewise, nanocarriers can be designed to respond to a range of specific biomolecules that may occur at the target site. In this volume we also cover dual and multi-responsive systems that combine stimuli that could be either internal or external. © 2015 Morgan & Claypool Publishers. All rights reserved

Smart external stimulus-responsive nanocarriers for drug and gene delivery

The concept of smart drug delivery vehicles involves designing and preparing a nanostructure (or microstructure) that can be loaded with a cargo, this can be a therapeutic drug, a contrast agent for imaging, or a nucleic acid for gene therapy. The nanocarrier serves to protect the cargo from degradation by enzymes in the body, to enhance the solubility of insoluble drugs, to extend the circulation half-life, and to enhance its penetration and accumulation at the target site. Importantly, smart nanocarriers can be designed to be responsive to a specific stimulus, so that the cargo is only released or activated when desired. In this volume we cover smart nanocarriers that respond to externally applied stimuli that usually involve application of physical energy. This physical energy can be applied from outside the body and can either cause cargo release, or can activate the nanostructure to be cytotoxic, or both. The stimuli covered include light of various wavelengths (ultraviolet, visible or infrared), temperature (increased or decreased), magnetic fields (used to externally manipulate nanostructures and to activate them), ultrasound, and electrical and mechanical forces. Finally we discuss the issue of nanotoxicology and the future scope of the field. © 2015 Morgan & Claypool Publishers. All rights reserved

Redox-sensitive smart nanosystems for drug and gene delivery

Background: Smart stimulus-responsive nanocarriers represent a rapidly growing class of drug-delivery systems for cancer and other diseases. Objective: The alterations of redox potential between the intracellular environment and the extracellular space have been widely utilized as a trigger for delivery of therapeutic agents by smart stimulus-responsive nanocarriers. We set out to review the scientific literature. Method: Published papers between 1980 and the present day were surveyed. Results: The advantages of redox-activated smart delivery of drugs, genes, and imaging agents include: the amplitude of the redox-responsive signal; the simple chemical features needed to trigger the activation process; and the relative simplicity of preparing these nanocarriers with an integrated redox-sensitive triggering element. Redox-sensitive nanovehicles are often sensitive to glutathione (GSH) as a regulator of cellular redox potential, which is a very important redox couple in mammalian cells. Other nanostructures can be designed to respond to oxidation, which may be useful for drug-delivery to sites with oxidative stress. Conclusion: Redox-responsive nanocarriers are a prominent member of the class of smart nanocarriers, and are expected to grow importance in coming years. � 2016 Bentham Science Publishers

Albumin nanostructures as advanced drug delivery systems

Introduction: One of the biggest impacts that the nanotechnology has made on medicine and biology, has been in the area of drug delivery systems (DDSs). Many drugs suffer from serious problems concerning insolubility, instability in biological environments, poor uptake into cells and tissues, sub-optimal selectivity for targets and unwanted side effects. Nanocarriers can be designed as DDSs to overcome many of these drawbacks. One of the most versatile building blocks to prepare these nanocarriers is the ubiquitous, readily available and inexpensive protein, serum albumin. Areas covered: This review covers the use of different types of albumin (human, bovine, rat, and chicken egg) to prepare nanoparticle and microparticle-based structures to bind drugs. Various methods have been used to modify the albumin structure. A range of targeting ligands can be attached to the albumin that can be recognized by specific cell receptors that are expressed on target cells or tissues. Expert opinion: The particular advantages of albumin used in DDSs include ready availability, ease of chemical modification, good biocompatibility, and low immunogenicity. The regulatory approvals that have been received for several albumin-based therapeutic agents suggest that this approach will continue to be successfully explored. © 2016 Informa UK Limited, trading as Taylor & Francis Group

Nanotechnology in diagnosis and treatment of coronary artery disease

Nanotechnology could provide a new complementary approach to treat coronary artery disease (CAD) which is now one of the biggest killers in the Western world. The course of events, which leads to atherosclerosis and CAD, involves many biological factors and cellular disease processes which may be mitigated by therapeutic methods enhanced by nanotechnology. Nanoparticles can provide a variety of delivery systems for cargoes such as drugs and genes that can address many problems within the arteries. In order to improve the performance of current stents, nanotechnology provides different nanomaterial coatings, in addition to controlled-release nanocarriers, to prevent in-stent restenosis. Nanotechnology can increase the efficiency of drugs, improve local and systematic delivery to atherosclerotic plaques and reduce the inflammatory or angiogenic response after intravascular intervention. Nanocarriers have potential for delivery of imaging and diagnostic agents to precisely targeted destinations. This review paper will cover the current applications and future outlook of nanotechnology, as well as the main diagnostic methods, in the treatment of CAD. © 2016 Future Medicine Ltd

Stimulus-responsive liposomes as smart nanoplatforms for drug delivery applications

Liposomes are known to be promising nanoparticles (NPs) for drug delivery applications. Among the different types of self-assembled NPs, liposomes stand out for their non-toxic nature and their possession of dual hydrophilic-hydrophobic domains. The advantages of liposomes include the ability to solubilize hydrophobic drugs, the ability to incorporate different hydrophilic and lipophilic drugs at the same time, lessening the exposure of host organs to potentially toxic drugs and allowing modification of the surface by a variety of different chemical groups. This modification of the surface, or of the individual constituents, may be used to achieve two important goals. First, ligands for active targeting can be attached that are recognized by cognate receptors overexpressed on the target cells of tissues. Second, modification can be used to impart a stimulus-responsive or "smart" character to the liposomes, whereby the cargo is released on demand only when certain internal stimuli (pH, reducing agents, specific enzymes) or external stimuli light, magnetic field, or ultrasound (US) are present. Here, we review the field of smart liposomes for drug delivery applications. © 2017 Walter de Gruyter GmbH, Berlin/Boston

Identification of a fourth cheY gene in Rhodobacter sphaeroides and interspecies interaction within the bacterial chemotaxis signal transduction pathway.

The Escherichia coli chemotaxis signal transduction pathway has: CheA, a histidine protein kinase; CheW, a linker between CheA and sensory proteins; CheY, the effector; and CheZ, a signal terminator. Rhodobacter sphaeroides has multiple copies of these proteins (2 x CheA, 3 x CheW and 3 x CheY, but no CheZ). In this study, we found a fourth cheY and expressed these R. sphaeroides proteins in E. coli. CheA2 (but not CheA1) restored swarming to an E. coli cheA mutant (RP9535). CheW3 (but not CheW2) restored swarming to a cheW mutant of E. coli (RP4606). R. sphaeroides CheYs did not affect E. coli lacking CheY, but restored swarming to a cheZ strain (RP1616), indicating that they can act as signal terminators in E. coli. An E. coli CheY, which is phosphorylated but cannot bind the motor (CheY109KR), was expressed in RP1616 but had no effect. Overexpression of CheA2, CheW2, CheW3, CheY1, CheY3 and CheY4 inhibited chemotaxis of wild-type E. coli (RP437) by increasing its smooth-swimming bias. While some R. sphaeroides proteins restore tumbling to smooth-swimming E. coli mutants, their activity is not controlled by the chemosensory receptors. R. sphaeroides possesses a phosphorelay cascade compatible with that of E. coli, but has additional incompatible homologues

Localization and environmental regulation of MCP-like proteins in Rhodobacter sphaeroides

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71531/1/j.1365-2958.1999.01226.x.pd