Over the past decade, researchers have established a definite relationship between Alzheimer's disease and nicotinic acetylcholine receptors (nAChRs). Not only do cholinergic activity and neuronal nAChR levels decrease as the disease progresses, but recent studies have also demonstrated that the beta-amyloid protein produced in Alzheimer's disease can directly and indirectly affect nAChR-mediated synaptic transmission. Researchers are currently trying to elucidate the mechanisms of these effects while simultaneously studying the pharmacological modification of nAChRs by other compounds. It is hoped that new drugs may be able to prevent the negative effects of beta-amyloid in vivo, and thus serve as treatment strategies for Alzheimer's disease.
Studies were undertaken to delineate the combustion products of a magnesium (Mg) ribbon on silica (SiO2) crucibles by analyzing the solid surface using X-ray photoelectron spectroscopy (XPS). The sample group included a control, two differently-stained crucibles, and the combustion product, magnesium oxide (MgO). Aluminum (Al) was found in both the raw Mg and the MgO powder, with an oxidation state comparable to that of aluminum oxide (Al2O3). Results of the study revealed evidence leading to the formation of aluminum carbide (Al4C3) as part of the surface integrity.
Startups vie for strategic positions in densely populated cities by paying high prices for rent, since the customer base they can establish is larger compared to suburban areas. For this paper, firms locate sequentially basing their decisions on correct expectations as to how their competitors locate and market-players face a non-uniform density function of customers. The solution is obtained using backward induction. Three types of market structures will be considered in this paper: duopoly, oligopoly, and perfect competition. The nature of these equilibriums differs from conventional papers in that firms face a uniform density of customers.
We applied the methods of supersymmetric quantum mechanics to differential equations that generate well-known special functions of modern physics. This application provides new insight into these functions and generates recursion relations among them. Some of these recursion relations are apparently new (or forgotten), as they are not available in commonly used texts and handbooks. This method can be easily extended to explore other special functions of modern physics.
This paper studies the dynamics of any population growing in a bioreactor with instantaneous perturbations caused by taking away or adding a biomass at certain moments. The case when the perturbations are of negligible length is investigated, and impulsive differential equations are used for modeling the situation. The studied populations either grow or decay exponentially between two consecutive perturbations. Several different models depending on the type of perturbations are examined; for each model, existence results and explicit formulas for the solutions are obtained. Theoretical results are applied to several real-life cases to predict the population sizes in time, as well as the instant and the amount of the perturbations. We can find a means to control the considered ecosystem using the obtained results for the new models, and save time and money for conducting experiments and measuring population size.
Cryptophycin is a promising drug in many cancer therapies. Unfortunately, cryptophycin is expensive to produce synthetically because of its complex structure; however, certain strains of micro-algae naturally produce cryptophycin. This work studies the production of cryptophycin from two strains of Nostoc sp., ATCC 53789 and GSV 224.
Copepod nauplii are marine zooplankton invertebrates that have been shown to be advantageous as a food source for larval finfish ornamentals when the larvae first begin to feed. Despite this potential, copepod nauplii have up not been reared in sufficient quantities to sustain the large-scale feeding of ornamental finfish in captivity until this point. The aim of this scientific investigation was to develop a protocol for the effective cultivation and collection of eggs from the calanoid copepod, Bestiolina similis, and to compare the rates of mortality and egg production in response to additions of various food sources and concentrations to optimize animal longevity and reproductive performance.
The creation of a paleohydrologic record for the Hawaiian Islands is essential to understanding future implications of climate change. Determining the oxygen isotope composition of diatoms present in Lake Waiau cores will allow the paleohydrology of the lake to be reconstructed, which can be related to the hydrologic history of the entire Hawaiian Islands. Prior to the isotopic analysis of the diatoms, they must be isolated from the rest of the sediment. This study attempts to determine an effective method for this isolation, as well as to identify the diatom species that were isolated.
The 16S rDNA genes of fourteen bacterial isolates derived from shrimp larvae were successfully amplified, cloned and sequenced. Comparison of the sequences with those available at the NCBI web site using BLAST (nr database) allowed for bacterial classification based on similarity indices of greater than or equal to 96%. These identifications were consistent with previous phenotypic analyses of the same isolates by their carbon source utilization patterns and fatty acid methyl esters (FAME). Use of 16S sequencing to identify bacteria to species level is not without problems.
The marine bacterium Streptomyces tenjimariensis is known to produce an array of primary and secondary metabolites. The mechanisms of genetic regulation and control of these metabolic production pathways have yet to be elucidated. In this study, two specific aspects of metabolism and gene expression in S. tenjimariensis were investigated: the expression of enzymes involved in the biosynthesis of aminoglycoside antibiotics and the extracellular breakdown of starch.
Although water quality is extremely important to the Hawaiian Islands in terms of tourism and coastal ecology, very few studies have been done to investigate water turbidity along the south shore of Oahu. The reintroduction of sediments from the sea floor to the water column plays a major role in the turbidity of this area, and is heavily influenced by physical oceanographic forces such as currents, swells, and tides. This study focuses on using Acoustic Doppler Current Profiler (ADCP) echo intensity to examine the relationship between the aforementioned physical forces and changes in suspended sediment concentration on the south shore of Oahu.
In the last few years, the severity of coral bleaching events and disease observances has increased worldwide. Very little is known about disease in the Hawaiian Islands, although it is a commonly held belief that conditions are generally unfavorable for disease development/establishment due to Hawaii's open ocean circulation and low human population. This study focuses on characterizing bacterial communities found on healthy and lesioned Montipora capitata, Porites compressa, and Porites lobata collected from various sites around Oahu, Hawaii including the North Shore, Hanauma Bay, Kaneohe Bay and Kahe Point.
Viral vectors can be used to introduce sequences that cause gene silencing in plants. In this study, a sequence from the salt-tolerant green alga Dunaliella salina was used to silence a DEAD box helicase gene in Nicotiana benthamiana, a plant related to tobacco. Phenotypic changes due to silencing were observed, and changes in expression of the DEAD box helicase gene were quantified using real-time PCR. The results suggest that the gene is involved in critical RNA processing functions. More generally, it was demonstrated that although N. benthamiana is only distantly related to D. salina, gene silencing could be induced in N. benthamiana using a sequence from D. salina; this indicates that it may be possible to use gene silencing in N. benthamiana to characterize genes from a wide variety of organisms.
In 1977, a series of functional growth hormone secretagogues (GHS), which activate the endogenous receptor of the stomach peptide ghrelin, were synthesized in order to stimulate growth hormone secretion from the pituitary gland. Following this work, subsequent efforts concentrated on the development of an orally active GHS with a long lasting effect and high bioavailability. This paper discusses the effect of the functional growth hormone GHS CP-477335 on the GH/IGF-I axis in tilapia, Oreochromis mossambicus, using both in vivo and in vitro experiments.
Through human activities, endocrine disrupting compounds (EDCs) have become ubiquitous in the aquatic environment. Although much research has examined the effects of these chemicals on reproduction, there remains a paucity of information regarding effects on growth. In order to study the effects of EDCs on growth, hepatocytes (liver cells) and pituitary cells were cultured from female tilapia, Oreochromis mossambicus, and exposed to heptachlor, a pesticide, and DDE, a by-product of the pesticide DDT. Cells and media were assayed for liver vitellogenin, IGFBPs, and pituitary GH.
Biofouling is the process by which living tissue or inert objects placed into aqueous environments are covered with a complex community of micro and macro organisms. The process begins with the formation of a microbial biofilm that subsequently serves as a suitable surface to which the larvae of macrofoulers attach and undergo metamorphosis into adult organisms. Biofilms can also coat medical devices imbedded in the human body and provide microbial pathogens a measure of protection from antibiotics. As such, the formation of microbial biofilms is a significant problem and strategies to inhibit their formation are needed.
Staphylococcus aureus is often found passively colonizing human skin and nasal passages. As an opportunistic pathogen, the bacterium can also cause infections that vary widely in their severity and in their susceptibility to antibiotic treatment. This variability is caused by differences in gene content among strains. One source of exposure to novel, potentially more virulent strains of S. aureus is recreational swimming areas, since S. aureus is readily shed from humans into water.
In the Azorean Archipelago, the limpet Patella candei gomesii Drouët (1858) exhibits two distinct habitat morphs with respect to shell morphology: mosca, which is highly conical and commonly found above high tide mark, and mansa, which is flatter and intertidal. Although both morphs occur microsympatrically, their distribution is not random. This paper examines the genetic diversity between the two morphs over a set of 10 enzyme loci. Specimens of both forms were sampled on the two most oriental islands of this archipelago. High genetic identity values were found, thus rejecting the notion of reproductive isolation within these populations or between both habitat morphs.
This study was designed to determine if Wnt signaling mediated through beta-catenin plays a role in the early proliferation and differentiation of human connective tissue progenitor cells (CTPs). Bone Marrow was aspirated from nine human donors. Marrow was processed to isolate CTPs in vitro using established methods, and cells were plated onto 16-well Lab-Tech chamber slides. At day 6, the cells were fixed using 4% paraformaldehyde in phosphate buffered saline (PBS), blocked with goat serum in PBS, and incubated/stained with a monoclonal mouse anti- beta-catenin antibody and a fluorescent secondary.
Trust is the foundation of a successful patient-dentist relationship, as with all other relationships. By engendering feelings of ease and confidence in his or her abilities, a skilled dentist is capable of allaying a patient's fears, and of rendering the dental encounter a pleasant and painless one. A heightened sense of trust also facilitates a patient's interactions with the dentist, provides a greater feeling of satisfaction with provided dental services, and promotes therapeutic compliance. Although few studies have directly examined trust, factors that comprise the concept were reviewed in order to recommend ways to increase trust in patient care.
The ability of a bacterium to adhere to various surfaces is important in environmental and biomedical applications. While studying bacterial adhesion in the laboratory, unwanted artifacts can be caused by cell preparation and treatment protocols, which are used in virtually all experimental investigations. We investigated the effects of three cell separation methods (centrifugation, multiple rounds of centrifugation, and filtration) on the retention behavior of two Gram-negative bacteria: Pseudomonas putida KT2442 and Escherichia coli HB101.
The present article will explore how the collapse of the pharyngeal airway during sleep, a phenomenon currently identified as an indicator of disease, may confer specific homeostatic benefits. More specifically, we will consider how the pathologically large size of the fleshy structures in the pharyngeal airway, along with relative hypotonicity of the pharyngeal musculature may have provided our ancestors with a selective advantage by enabling them to reduce nocturnal, respiratory heat loss.
The present experiment investigated relationships among dominance status, sex, risk, and feeding behavior using house sparrows, Passer domesticus. Feeding behavior was observed in wild male and female house sparrows at high- and low-risk food sites (i.e., those with and without a model snake, respectively). At high-risk sites, birds avoided the snake by feeding on the opposite side of the food source. Small-badge (presumed subordinate) males far outnumbered other males at high-risk feeding sites, whereas medium-badge (presumed intermediate ranked) males far outnumbered other males at the low-risk sites. For low-ranking males, this strategy might maximize food acquisition and reduce the cost of competition. Overall, the present findings suggest that animals' feeding behaviors and responses to risk differ depending on social rank.
Spinal cord injury inflicts considerable damage on human physical and physiological regulation and cellular integrity. Although drug therapy and functional electrical stimulation are currently used as treatment, neuronal regeneration in the Central Nervous System (CNS) is crucial for re-establishing neural pathways and function. Regeneration researchers strive to create the most permissive environment for neural growth through strategies such as manipulating gene expression, removing inhibitory factors of glial cells, making antibodies against destructive myelin-associated proteins, injecting neurotrophins and other growth factors, grafting Schwann cells and olfactory ensheathing cells, and even introducing pluripotent stem cells.
Magnetic fields both positively and negatively affect the electron beam orbit in a 100 keV beamline in the Test Lab, Injector Test Stand (ITS) at Thomas Jefferson National Accelerator Facility (Jlab). DC air-core magnets and iron solenoid magnets are used to steer and focus the electron beam throughout the beamline, but time-varying magnetic fields (prominent at power line frequency) adversely modulate the electron beam orbit. We took a number of steps to identify the sources of these fields and engineer a design to shield the beamline.
Given the current projections, maize will become the largest crop worldwide within a few years. It is vital that a crop this important have a well-defined genome. One hundred and thirty Bacterial Artificial Chromosome (BAC) maize sequences have been analyzed through various bioinformatics software, such as BLAST (Basic Local Alignment Searching Tool), GenScan, and Clustalx. BLAST analysis revealed that the maize genome is composed of diverse sequences that represent a variety of families of retrotransposons. These are segments of DNA that move from one location on a chromosome to another, resulting in genetic variation.
Cadmium is a toxic heavy metal released from smelting and absorbed and bioaccumulated by organisms along the food chain. Cadmium binds to organic molecules by forming bonds with sulfur and nitrogen, thereby inactivating proteins, and is one of the three contaminants which, according to the EPA, pose the most threat to the environment. The objective of this study was to determine the long-term effect of various concentrations of cadmium chloride (CdCl2) on the growth of cultures of Chlamydomonas reinhardtii, a unicellular green algae found in fresh water, by measuring optical density and chlorophyll concentration.
Some researchers claim nucleosomes disappear during transcriptional activation, and others claim nucleosomes reposition themselves. For example, the PH05 gene found in Saccharomyces cerevisiae requires nucleosome repositioning prior to transcription. This research focuses on the importance of nucleosome remodeling in transcription. A procedure developed in a previously published study used a photochemical reagent to cross-link a cysteine on the nucleosome, followed by nucleosome mapping on a sequencing gel.
Paper bank notes were collected in and around The George Washington University Hospital. The notes were washed in detergent to remove bacteria, which were then grown on mannitol salts agar with or without antibiotic supplementation. Yellow colonies were observed, which was indicative of Staphylococcus Aureus strains. Various strains were treated to purify plasmid DNA. The strains were also cured with Acridine Orange to remove plasmid DNA, and the strains with and without Acridine Orange were grown on vancomycin-supplemented media to test if the plasmid DNA in the strain was related with conferring vancomycin resistance.
The role of advanced glycation end-products (AGEs) in the development of complications in individuals with insulin-dependent diabetes mellitus (IDDM) has been explored by previous studies. However, the relationship between these reactive AGEs and diabetic complications are still somewhat unknown. Glycation (nonenzymatic glycosylation) processes, also known as the Maillard reactions, are a series of reactions between carbohydrates and free amino groups of proteins. The preliminary intermediates, (Amadori products; 1-amino, 1-deoxy, 2-ketoses), ultimately result in the formation of AGEs. AGEs in humans have been predominantly chemically characterized by the detection of pentosidine and N-carboxy-methyl lysine (CML). Both pentosidine and CML have been found to accumulate in skin and lens collagen matrix at accelerated rates in diabetic patients.
With most pathogenic and etiologic agents of deadly diseases acquiring resistance to currently used drugs, the development and formulation of vaccines against predominant infectious diseases has taken centre stage. Our review aims, based on our understanding and knowledge of the process of pathogenesis and its intricacies in particular, to throw light on the aspects of vaccine development. The basic platform for formulating a vaccine involves deciphering the kinds of immune responses to the various antigenic factors of the pathogen. Other particulars, such as immunological memory (primarily mediated by antibodies post-natally), immunopathology of infections, and the selective balance of Th1-Th2 responses are also considered grounding factors for the construction of "immunity eliciting vaccines". The nature of vaccines (either humoral antibody immunity inducing or cell-mediated immunity inducing) depends on the location (extracellular or intracellular) and the expression of the antigens selected for incorporation. To maintain the synergism between the kind of immunity conferred by the vaccines and the cellular location of the included antigens, new findings are gathered about the virulence factors such as toxins, adhesins, invasins (mostly enzymes), anti-apoptotic factors, anti-phagocytic factors, and many more molecules that aid in pathogenesis and invasiveness. The concept of an all-in-one vaccine versus a one-in-one vaccine is also discussed. Bioinformatics tools and algorithms like BLAST and FASTA are nowadays being adopted as a means to identify and detect common target antigens against Gram negative bacterial pathogens. One of the more recently identified and well-studied gram negative bacterial candidates has been Choline phosphorylase. Homology searches have thus facilitated the discovery of potential candidates for an all-in-one vaccine.
Pharmacogenomics is the study of genetic differences responsible for the variability in drug response among individual patients. Emerging from this new science is the development of diagnostic tools crucial for decreasing drug side effects and optimizing treatment strategies. However, both application and progress have been troublesome in guiding treatment of genetically-linked diseases such as cancer and diabetes. The complexity of multiple gene interactions requires a collaborative effort to understand the genetic bases of variable drug response. Societal quandaries also burden research. The novel genomic information to be used in tackling disease may be viewed as discriminatory factors involving winners and losers. Concerns of privacy and cost as well as changes to today's medical education and practice will unsettle the American healthcare system. This article reviews the feasibility and potential of applying the latest advancements in genomics to medicine and drug development.
Acquired immuno deficiency syndrome is a disease that manifests itself as a result of gene silencing and changing gene patterns caused by human immuno virus infection. Inspite of sustained efforts by the scientific community, a permanent treatment method for this infection has not been formulated till date. With the advancements in stem cell research, animal cell culture and genetic engineering, it is possible to devise a treatment for human immuno virus Infection. This article gives an insight into the convergence of the above mentioned technologies to yield a technique called Chromosome Engineering', which might be a viable treatment option for human immuno virus and other retroviral infections.
The molecular basis for cell migration during morphogenesis has been a topic of intense interest and has yet to be fully understood. It is shown here how it is possible to construct a matrix to reflect different types of morphological changes associated with the "mass movements" which occur in Drosophila embryological development. It is also shown how this matrix can be correlated to a data from a time course microarray, to determine genes most correlated to their corresponding morphological change. Application of this method represents a novel methodology for discovering function for genes of unknown function.