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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

The preparation of Coordination Compounds of Rhodium (III) and Glutamic acid and Substituted Glutamic Acids

Kalberer, Herman William 01 January 1969 (has links) (PDF)
The father of coordination chemistry was Alfred Werner (1866- 1919). Werner's theory was largely responsible for the renewed interest in, and rapid growth of, inorganic chemistry around the turn of the century. He postulated that there were two types of valence, primary and secondary, which correspond, in modern terminology, to oxidation state and coordination number. The primary valences must be either negative ions, neutral molecules or, occasionally even, positive ions (11). He also postulated that the secondary valences are directed in space about the central ion, not only in the solid state, but also when the complex is in solution. This was the first attempt to describe the stereochemistry of metal complexes and the various isometric compounds which were known at the time. The properties and stereochemistry of such complexes, which were explained by Werner's theory, are the basis of coordination chemistry.
42

The Effect of Microdosing Classical Psychedelics On Cognitive Performance

Harris, Michael 01 January 2021 (has links)
Public interest and scientific inquiry are currently bringing psychedelic research back into the spotlight after a decades-long respite from clinical human trials. A majority of the research during this recent renaissance has surrounded applications of psychedelics in the fields of mental health. Less attention is being focused to other research areas where psychedelics may also prove informative, such as cognition and information processing. A common trend taking place is the act of administering very small doses of psychedelics as a potential cognitive enhancer, called microdosing. With less research being focused on these areas however, it is not well documented whether the effects of microdosing provide consistent or measurable results. The current study aimed to test the effects of microdosing on information processing using a research design originally administered in stimulant research on attention. Participants were anonymously recruited from various psychedelic microdosing forums online (N = 4), and compared in a between-subjects design against a separate sample who did not microdose (N = 10). Results from the task did not yield significant effects, possibly due to an underpowered sample. However, trends in the results highlighted the potential for an effect opposite to that of the proposed hypothesis. Recommendations have been provided for additional research to improve upon the design of the study and to also propose alternate hypotheses regarding the effects microdosing on information processing as well as other areas of study that may also benefit from microdosing research.
43

Faculty Applicants' Attempt to Inflate CVs Using Predatory Journals

Pond, Brooks B., Brown, Stacy D., Stewart, David W., Roane, David S., Harirforoosh, Sam 01 January 2019 (has links)
Recently, scientific publishing has experienced an expansion of journals and publishers whose primary goal is profit and whose peer review process is virtually non-existent. These “predatory” or “opportunistic” journals pose a threat to the credibility and integrity of legitimate scientific literature, and quality science. Unfortunately, many scientists choose to publish in these journals and/or serve on their editorial boards, either due to ease of rapid publication or naivety. Here, we highlight the extensive use of predatory publications or editorial board involvement by applicants applying for a faculty position in the Pharmaceutical Sciences department at the Bill Gatton College of Pharmacy at East Tennessee State University. We caution search committees at other pharmacy schools to thoroughly examine applicant curricula vitarum (CVs) for predatory publishing.
44

Sex Differences in the Kinetic Profiles of d- and l- Methylphenidate in the Brains of Adult Rats

Bentley, J., Snyder, F., Brown, Stacy D., Brown, R. W., Pond, Brooks B. 01 January 2015 (has links)
OBJECTIVE: Methylphenidate is commonly used in the treatment of Attention Deficit Hyperactivity Disorder and narcolepsy. Methylphenidate is administered as a racemic mixture of the d- and l- threo enantiomers; however, the d-enantiomer is primarily responsible for the pharmacologic activity. Previous studies of the behavioral effects of methylphenidate have highlighted sex differences in the responsiveness to the drug, namely an increased sensitivity of females to its stimulatory effects. These differences may be due to differences in the uptake, distribution, and elimination of methylphenidate from male and female brains. Therefore, we compared the pharmacokinetics of d- and l- threo methylphenidate in the brains of male and female rats. MATERIALS AND METHODS: Adult male and female Sprague-Dawley rats were injected with 5 mg/kg d, l- threo methylphenidate, and whole brains were collected at various time points following injection. We measured methylphenidate concentrations utilizing chiral high pressure liquid chromatography followed by mass spectrometry. RESULTS: Females exhibited consistently higher brain concentrations of both d- and l- methylphenidate and a slower clearance of methylphenidate from brain as compared to males, particularly with the active d-enantiomer. CONCLUSIONS: The increased sensitivity of females to methylphenidate may be partially explained by an increase in total brain exposure to the drug.
45

Sodium borohydride reduction of quinicine

Dunnette, David Arthur 01 January 1969 (has links) (PDF)
Prom the dawn of history man has searched among the natural products of his environment for substances to com- bat his ills. The most widespread of these ills, malaria, today afflicts some 300 million people each year (1). The causative parasite, a protoza, in a somber of the Plasmodium genus and is transmitted through the saliva of the female Anopheles mosquito.
46

Ponatinib-induced Cardiac Toxicity is Mediated by Impaired Angiogenesis

Altiokka, Imran 01 January 2023 (has links) (PDF)
Ponatinib is a third-generation tyrosine kinase inhibitor approved for Chronic Myelogenous Leukemia and Philadelphia Chromosome Positive Acute Lymphoblastic Leukemia and it is the only tyrosine kinase inhibitor able to bind T315I mutation of BCR-ABL1 (Breakpoint Cluster Region and Abelson1) kinase protein. However, the cardiotoxic adverse reactions related to Ponatinib treatment can result in serious health problems and discontinuation of the therapy. The underlying mechanisms of Ponatinib-induced cardiotoxicity are not known. This study hypothesized that Ponatinib downregulates leptin and serpine-1 expressions and inhibits angiogenesis through the adipokine-induced p38 MAPK signaling pathway in mouse hearts. To evaluate this proposed pathway C57BL/6J mice were divided into two groups: control and ponatinib. After 14 days of the injections, mice were sacrificed and the heart samples were collected for histological analysis and evaluation of mRNA and protein expression levels. The RNA sequence analysis of heart samples was used to detect the main angiogenic markers affected by the treatment. Further analysis was done by Western Blot, RT-PCR, and immunohistochemistry. The heart function was assessed by echocardiography. Overall, the data indicated that the angiogenic response was inhibited by Ponatinib treatment through leptin and serpine-1-mediated p38 MAPK pathway. The anti-angiogenic response is an important underlying pathological mechanism that could lead to disruption of heart function and the echocardiography data confirmed that ponatinib-treated mice showed impaired heart function. Our study suggested that the potential underlying mechanism of Ponatinib-induced cardiotoxicity can be explained by serpine-1 and leptin-mediated angiogenic pathways.
47

NOVEL SPOXAZOMICINS DERIVED FROM <em>STREPTOMYCES</em> SP. RM-14−6 ATTENUATE ETHANOL INDUCED CYTOTOXICITY <em>IN VITRO</em>

Saunders, Meredith A. 01 January 2016 (has links)
An estimated 13.9% of Americans currently meet criteria for an alcohol use disorder. Ultimately, chronic alcohol use may result in neurological deficits, with up to 85% of alcoholics exhibiting signs of cognitive decline. However, biochemical and behavioral factors contributing to this decline have remained elusive. Our ongoing research program encompasses a multi-tiered screening of a natural product library and validation process to provide novel information about mechanisms underlying these deficits and to identify novel chemical scaffolds to be exploited in the development of pharmacological treatments for alcohol use disorders in a rodent organotypic hippocampal slice culture mode. Experiment 1 sought to establish a 48 h high throughput model for testing novel scaffolds against ethanol (EtOH) toxicity. Experiment 2 tested multiple natural product compounds for their ability to attenuate ethanol-induced cytotoxicity. Results from Experiment 1 revealed EtOH (100 mM) induced significant cytotoxicity at 48 h. Trolox (100 µM), a potent antioxidant, was found to reduce ethanol-induced cytotoxicity in this assay. Experiment 2 revealed two spoxazomicins (1, 1-1) demonstrated potent cytoprotective effects against ethanol toxicity. These findings highlight the potential applications of these novel scaffolds for use in the treatment of alcohol use disorder.
48

Chemical Probes for Protein α-N-Terminal Methylation

Mackie, Brianna D 01 January 2017 (has links)
While protein α-N-terminal methylation has been known for nearly four decades since it was first uncovered on bacteria ribosomal proteins L33, the function of this modification is still not entirely understood. Recent discoveries have demonstrated α-N-terminal methylation is essential to stabilize the interactions between regulator of chromosome condensation 1 (RCC1) and chromatin during mitosis, to localize and enhance the interaction of centromere proteins (CENPs) with chromatin, and to facilitate the recruitment of DNA damage-binding protein 2 (DDB2) to DNA damage foci. Identification of N-terminal methyltransferase 1 (NTMT1) unveiled the eukaryotic methylation writer for protein α-N-termini. In addition, NTMT2 that shares over 50% sequence similarity, has been identified as another mammalian protein α-N-terminal methylation writer. Knockdown of NTMT1 results in mitotic defects and sensitizes chemotherapeutic agents in breast cancer cell lines, while NTMT1 knockout mice showed premature aging. Additionally, NTMT1 has been shown to be overexpressed in a colorectal and melanoma tumor tissues, and in lung and liver cancer cell lines. Given the vast array of clinical relevance, chemical probes and inhibitors for NTMT1 are vital to elucidate information about the function and downstream process of protein α-N-terminal methylation. Therefore, 47 peptidomimetic compounds have been synthesized that target NTMT1. These peptide-based compounds range from three to six amino acids in length and the top 5 compounds have 3- to 300- fold selectivity for NTMT1 compared to other methyltransferases. An inhibition mechanism study has also been performed to verify the inhibitors are targeting the NTMT1 peptide binding site. Seven compounds have an IC50 of less than 5 µM and our top inhibitor, BM-47, has an IC50 of 0.32 µM ± 0.06 for NTMT1. To further elucidate information about the NTMTs and their downstream effects, we utilized photoaffinity probes to target these enzymes. Our 6 photoaffinity probes exhibited in a dose- and time-dependent manner. Probe labeling has been shown to be driven by recognition and selectively and competitively label the NTMT writers in a complex cellular mixture. Our results also provided the first indication of substrate preferences among NTMT1/2. Methylated photoaffinity probes were also synthesized to identify novel proteins that recognize a methylated N-terminus and shed light on the function of α-N-terminal methylation.
49

Precursor Supply and Polyketide Antibiotic Biosynthesis in Oil-based Industrial Fermentations of Streptomyces Cinnamonensis

Li, Chaoxuan 01 January 2007 (has links)
Polyketides are a group of bioactive natural products synthesized by bacteria, fungi and plants with various acyl-CoA precursors, such as malonyl-CoA, methylmalonyl-CoA and ethylmalonyl-CoA. A sufficient supply of these precursors is a prerequisite for the high level production of polyketide products. A thorough understanding of relative roles of various metabolic pathways involved in precursor supply makes increased production by genetical manipulation, and thus rational strain improvement, a reality. Monensin A is a polyketide antibiotic assembled from one ethylmalonyl-CoA, seven methylmalonyl-CoA and five malonyl-CoA molecules by Streptomyces cinnamonensis. In the present work, the origin of these biosynthetic precursors was investigated using an industrially mutagenized monensin producer and industrial fermentation conditions. A hitherto disregarded metabolic pathway was discovered to play a significant role in providing methylmalonyl-CoA for monensin biosynthesis by gene disruption, isotope-labeling of monensin and analysis of in vivo acyl-CoA pools. This pathway starts from biosynthesis of butyryl-CoA from two molecules of acetyl-CoA, and goes through the intermediate of isobutyryl-CoA, and finally produces methylmalonyl-CoA by direct oxidation of the pro-S methyl group of isobutyryl-CoA.Industrial fermentation of the industrially mutagenized monensin producer yields significantly more monensin than the routine laboratory fermentation. This suggested the presence of abundant in vivo malonyl-CoA and methylmalonyl-CoA in this process and presented an opportunity to utilize it as a biological system for the high-titer production of heterologous polyketides derived from malonyl-CoA and/or methylmalonyl-CoA. The tetracenomycin C polyketide synthase (PKS) synthesizes tetracenomycin C, a polyketide with ten molecules of malonyl-CoA. In this work, the tetracenomycin C PKS gene cluster was introduced into two industrially mutagenized strains of Streptomyces cinnamonensis. Unprecedented multi-gram/liter of tetracenomycin production was observed in the resulting two strains, indicating the high potential of industrially mutagenized monensin production strains as efficient hosts for the production of malonyl-CoA-derived polyketides. For additional improvement in tetracenomycin yield, we attempted to increase malonyl-CoA supply to tetracenomycin C PKS by genetically manipulating metabolic pathways affecting production of malonyl-CoA and eliminating competition from monensin PKS for malonyl-CoA. However, only decreased tetracenomycin production was observed, demonstrating that the regulation of malonyl-CoA-related metabolic pathways is a complex process.
50

Effects of Nicotinic Acetylcholine Receptor Agonists in Assays of Pain-Stimulated and Pain-Depressed Behavior in Rats

Freitas, Kelen 01 January 2015 (has links)
Though a host of analgesics have been developed to alleviate pain, especially acute pain, significant side effects and a lack of long-term efficacy have encouraged research attempts to pursue novel targets that may be associated with fewer side effects or a more sustained efficacy. Among these new targets are members of the nicotinic family of acetylcholine receptors (nAChRs). The non-selective nAChR agonists nicotine and epibatidine have been shown to function as potent antinociceptive drugs in many acute and chronic preclinical pain models, while nicotine has produced analgesic effects in humans. However, these non-selective nAChRs agonists also produce various side effects, including gastrointestinal and cardiovascular complications that limit clinical utility. To reduce these side effects, recent research has focused on evaluating the potential role of specific nAChR subtypes in the modulation of nociception. Traditionally, assays of pain-stimulated behaviors, or behaviors that increase in rate, frequency or intensity after presentation of a noxious stimulus, have been used to evaluate nAChR agonists and other classes of candidate analgesics pre-clinically. However, clinically relevant pain states are often associated with the depression of behavior; for example in humans, pain is often accompanied by impaired function in daily activities and depression of mood. To address these depressant manifestations of pain, novel preclinical assays have been developed to assess the expression and pharmacological modulation of pain-depressed behaviors, or behaviors that decrease in rate, frequency or intensity after presentation of a noxious stimulus. Additionally, the effects of nAChR agonists in preclinical assays of pain-depressed behavior are unknown. In assays of pain-stimulated behavior, agonism of α4β2* receptors appears to play a prominent role in antinociception produced by drugs that target nAChRs. Recent research suggests that α7 nAChR subtype might be an alternative target. Accordingly, the primary goal of this dissertation was to compare antinociceptive effects of the nAChR agonist nicotine and more selective nicotinic agonists in assays of pain-stimulated and pain-depressed behavior. Results from this body of work show that both nicotine and the more selective α4β2* agonist 5-I-A-85380 produced antinociception in both types of assays, whereas an α7 agonist did not. Taken together, these results suggest that α4β2* nAChR agonists may be especially effective to treat signs of pain-related behavioral depression; however nonselective behavioral effects of these compounds may contribute to apparent antinociception. Studies of nAChR agonist effects on pain-depressed behavior were conducted using an assay of intracranial self-stimulation (ICSS) as a baseline behavior that is depressed by noxious pain stimuli, and pain-related depression of ICSS can be selectively alleviated by clinically effective analgesics. As a prelude to studies of nAChR agonist effects on pain-related depression of ICSS, a preliminary study was conducted to assess effects of nicotine and 5-I-A-85380 on ICSS in the absence of a noxious stimulus. These studies indicated that selective α4β2* agonists may have higher abuse potential than nicotine. Additionally, cognitive function is one domain of behavior that may be impaired by pain, and nAChR agonists are used to treat cognitive impairment produced by other non-pain pathologies. Accordingly, a final goal of this project was to develop an assay of pain-related cognitive impairment in rats that could be used to evaluate effects of nAChR agonists. Although results of this study did provide evidence for pain-related impairment of cognition, the effects of the pain stimuli were sufficiently variable and transient to make this procedure impracticable for use in studies with nAChR agonists.

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