Modulation of NMDA Receptor Activity During Physiological and Pathophysiological Events

N-methyl-D-aspartate receptors (NMDARs) are ionotropic glutamate receptors that serve crucial signaling and neurotrophic functions throughout the central nervous system. Both hyperfunction and hypofunction of NMDARs are associated with neurological and neuropsychiatric conditions. Thus, both positive and negative pharmacological NMDAR modulators are of clinical interest as treatments. Understanding drug mechanisms could lead to more rational drug design. Memantine and ketamine are NMDAR open channel blockers that exhibit similar pharmacodynamics at NMDARs but have different clinical uses. Memantine improves cognitive decline during Alzheimer\u27s disease. Ketamine is an anesthetic and analgesic with psychotomimetic effects, but it is also a rapid acting and long-lived antidepressant. How these mechanistically similar blockers mediate different effects on behavior is unclear, but we hypothesized that unappreciated differences in their pharmacodynamics may contribute. This thesis investigated effects of memantine and ketamine during pathological (excitotoxic) and physiological activity in vitro, where pharmacokinetic effects could largely be ignored. We focused on non-steady state conditions that mimic synaptic transmission. I found that synaptic NMDAR activation is responsible for hypoxic excitotoxic cell death and revealed that memantine, a putative selective extrasynaptic receptor blocker, acquires its selectivity as a result of tonic agonist presentation rather than from affinity for specific populations. Further investigation into the similar synaptic pharmacodynamics of memantine and ketamine revealed a subtle difference in their response to voltage perturbations that was unmasked during physiological activity by increasing the open probability of the channel or by very strong activity. This suggests that regional differences in activity or channel open probability in vivo may control the efficacy of these blockers and partially explain their clinical differences. To further explore properties of ketamine relevant to its antidepressant action, I examined how its pharmacodynamics compares to its major metabolite, norketamine, and to chemical biology analogues of ketamine that show promise in tracking alternative targets for ketamine. In all, these studies reveal mechanistic insights into the pharmacodynamics of two NMDAR channel blockers that may partly explain their clinical effects

A Study of the Symbolism in Three Novels of John Steinbeck: To A God Unknown, The Pearl, and The Winter of Our Discontent

A monograph presented to the faculty of the School of Humanities at Morehead State University in partial fulfillment of the requirement for the Degree of Master of Arts by Ruth Bradbury Emnett in July of 1968

Sarcocystis of Deer in South Dakota

The incidence of Sarocystis, a protozoan parasite, in white-tailed deer and mule deer in South Dakota was determined through histological preparation and microscopic examination of tongue samples throughout the state. The percentage of Sarcocystis infection for both species of deer was determined for prairies east of the Missouri River, west of the Missouri River, and the Black Hills of western South Dakota. Sixteen percent of the white-tailed deer tongues from East River and 69 percent from West River, and 74 percent from the Black Hills were positive. Mule deer were 88 percent, 78 percent and 75 percent positive from East River (counties bordering the Missouri River), West River, and the Black Hills respectively. Of 50 tongue samples obtained from both species of deer during a special anterless season in the Black Hills (1978), 66 percent were infected. Experimental coyotes and dogs were fed naturally infected Sarcocystis tissue from white-tailed and mule deer obtained from the Black Hills. Fecal samples were recovered and examined for sporocysts. Two red foxes, one grey fox one bobcat, and one racoon were also fed infected met to determine their role is any as definitive (final) hosts of Sarcocystis. All coyotes, dogs, and the grey fox shed sporocysts, while none were recovered from the other animals. Sporocysts from coyotes fed white-tailed and mule deer meat were counted and concentrated into an inoculum for oral administration to two experimental white-tailed deer fawns in separate experiments. One fawn given sporocysts from coyote feces fed mule deer tissue died two days later (not Sarcocystis related). The other fawn was euthanized 85 days after inoculation. Sections of heart, tongue, esophagus, diaphragm, and skeletal muscle were found to be heavily infected with Sarcocystis, while a control fawn’s tissues were negative

Relationships Among Glycolytic Potential, Dark Cutting (Dark, Firm, and Dry) Beef, and Cooked Beef Palatability

One hundred beef carcasses were selected at three packing plants and were used to determine the relationship between glycolytic potential (GP) and dark, firm, and dry (DFD) beef and to determine the effects of DFD status and GP on cooked beef palatability. Eight individual muscles were excised from one hindquarter of each carcass at d 7 postmortem: longissimus lumborum, psoas major, gluteus medius, tensor fasciae latae, rectus femoris, semimembranosus, biceps femoris, and semitendinosus. Ultimate pH, colorimeter readings, and Warner-Bratzler shear force were determined for all eight muscles at d 7 postmortem. A ninemember trained sensory panel evaluated cooked longissimus lumborum, gluteus medius, and semimembranosus steaks. Traits determined solely for the longissimus lumborum were GP (2 × [glycogen + glucose + glucose- 6-phosphate] + lactate) and ether-extractable fat. A curvilinear relationship existed between GP and ultimate pH within the longissimus muscle. There appeared to be a GP threshold at approximately 100 mol/g, below which lower GP was associated with higher ultimate pH and above which GP had no effect on ultimate pH. The greatest pH and muscle color differences between normal and DFD carcasses were observed in the longissimus lumborum, gluteus medius, semimembranosus, and semitendinosus muscles. Cooked longissimus from DFD carcasses had higher shear force values (46% greater) and more shear force variation (2.3 times greater variation) than those from normal carcasses. Dark cutting carcasses also had higher shear force values for gluteus medius (33% greater) and semimembranosus (36% greater) than normal carcasses. Sensory panel tenderness of longissimus, gluteus medius, and semimembranosus was lower for DFD carcasses than for normal carcasses. Longissimus and gluteus medius flavor desirability scores were lower for DFD than for normal carcasses. Steaks from DFD carcasses had more off-flavor comments than steaks from normal carcasses, specifically more “peanutty,” “sour,” and “bitter” flavors. The DFD effect of higher shear force values was approximately five times greater (+3.11 kg vs +0.63 kg) for carcasses with “slight” marbling scores than for carcasses with “small” marbling scores. In general, higher GP was associated with increased tenderness, even among normal carcasses. In conclusion, low GP was associated with DFD beef and resulted in substantially less-palatable cooked steaks

Pediatric glioma-associated KIAA1549:BRAF expression regulates neuroglial cell growth in a cell type-specific and mTOR-dependent manner

Tandem duplications involving the BRAF kinase gene have recently been identified as the most frequent genetic alteration in sporadic pediatric glioma, creating a novel fusion protein (f-BRAF) with increased BRAF activity. To define the role of f-BRAF in gliomagenesis, we demonstrate that f-BRAF regulates neural stem cell (NSC), but not astrocyte, proliferation and is sufficient to induce glioma-like lesions in mice. Moreover, f-BRAF-driven NSC proliferation results from tuberin/Rheb-mediated mammalian target of rapamycin (mTOR) hyperactivation, leading to S6-kinase-dependent degradation of p27. Collectively, these results establish mTOR pathway activation as a key growth regulatory mechanism common to both sporadic and familial low-grade gliomas in children

A clickable analogue of ketamine retains NMDA receptor activity, psychoactivity, and accumulates in neurons

Ketamine is a psychotomimetic and antidepressant drug. Although antagonism of cell-surface NMDA receptors (NMDARs) may trigger ketamine’s psychoactive effects, ketamine or its major metabolite norketamine could act intracellularly to produce some behavioral effects. To explore the viability of this latter hypothesis, we examined intracellular accumulation of novel visualizable analogues of ketamine/norketamine. We introduced an alkyne “click” handle into norketamine (alkyne-norketamine, A-NK) at the key nitrogen atom. Ketamine, norketamine, and A-NK, but not A-NK-amide, showed acute and persisting psychoactive effects in mice. This psychoactivity profile paralleled activity of the compounds as NMDAR channel blockers; A-NK-amide was inactive at NMDARs, and norketamine and A-NK were active but ~4-fold less potent than ketamine. We incubated rat hippocampal cells with 10 μM A-NK or A-NK-amide then performed Cu(2+) catalyzed cycloaddition of azide-Alexa Fluor 488, which covalently attaches the fluorophore to the alkyne moiety in the compounds. Fluorescent imaging revealed intracellular localization of A-NK but weak A-NK-amide labeling. Accumulation was not dependent on membrane potential, NMDAR expression, or NMDAR activity. Overall, the approach revealed a correlation among NMDAR activity, intracellular accumulation/retention, and behavioral effects. Thus, we advance first generation chemical biology tools to aid in the identification of ketamine targets

Association of PPARγ2 polymorphisms with carcass and meat quality traits in a Pietrain x Jinhua F2 population

The PPARγ2 gene is a key regulator of both proliferation and preadipocyte differentiation in mammals. Herein its genotype and allele frequencies were analyzed using PCR-SSCP in eight pig breeds (N = 416). Two kinds of polymorphisms of the PPARγ2 gene were detected, including a previously reported shift SNP A177G (Met59Val) in exon 1 and a novel silent mutation G876A in exon 5. The results revealed that European pig breeds carry a higher allele A frequency at the A177G locus and a fixed GG genotype at the G876A locus. Allele A at the G876A locus was only found in Jinhua pigs. The association between haplotype (A177G/G876A) and carcass and meat quality traits was analyzed in a Pietrain x Jinhua F2 population (N = 248). The PPARγ2 gene was found to be significantly associated with backfat thickness at the shoulder (p < 0.05), 6–7th ribs (p < 0.01), last rib (p < 0.01), gluteus medius (p <0.05) and ham weight (p < 0.01). Significant effects of different haplotypes on ham weight and backfat thickness at the 6–7th ribs, last rib, and gluteus medius were also observed

An interpretive review of selective sweep studies in Bos taurus cattle populations: identification of unique and shared selection signals across breeds

This review compiles the results of 21 genomic studies of European Bos taurus breeds and thus provides a general picture of the selection signatures in taurine cattle identified by genome-wide selection-mapping scans. By performing a comprehensive summary of the results reported in the literature, we compiled a list of 1,049 selection sweeps described across 37 cattle breeds (17 beef breeds, 14 dairy breeds and 6 dual-purpose breeds), and four different beef-vs-dairy comparisons, which we subsequently grouped into core selective sweep (CSS) regions, defined as consecutive signals within 1 Mb of each other. We defined a total of 409 CSSs across the 29 bovine autosomes, 232 (57%) of which were associated with a single-breed (Single-breed CSSs), 134 CSSs (33%) were associated with a limited number of breeds (Two-to-four-breed CSSs) and 39 CSSs (9%) were associated with five or more breeds (Multi-breed CSSs). For each CSS, we performed a candidate gene survey that identified 291 genes within the CSS intervals (from the total list of 5,183 BioMart-extracted genes) linked to dairy and meat production, stature and coat colour traits. A complementary functional enrichment analysis of the CSS positional candidates highlighted other genes related to pathways underlying behaviour, immune response and reproductive traits. The Single-breed CSSs revealed an over-representation of genes related to dairy and beef production, this was further supported by over-representation of production-related pathway terms in these regions based on a functional enrichment analysis. Overall, this review provides a comparative map of the selection sweeps reported in European cattle breeds and presents for the first time a characterization of the selection sweeps that are found in individual breeds. Based on their uniqueness, these breed-specific signals could be considered as divergence signals, which may be useful in characterising and protecting livestock genetic diversity

Wearables in medicine

Wearables as medical technologies are becoming an integral part of personal analytics, measuring physical status, recording physiological parameters, or informing schedule for medication. These continuously evolving technology platforms do not only promise to help people pursue a healthier life style, but also provide continuous medical data for actively tracking metabolic status, diagnosis, and treatment. Advances in the miniaturization of flexible electronics, electrochemical biosensors, microfluidics, and artificial intelligence algorithms have led to wearable devices that can generate real-time medical data within the Internet of things. These flexible devices can be configured to make conformal contact with epidermal, ocular, intracochlear, and dental interfaces to collect biochemical or electrophysiological signals. This article discusses consumer trends in wearable electronics, commercial and emerging devices, and fabrication methods. It also reviews real-time monitoring of vital signs using biosensors, stimuli-responsive materials for drug delivery, and closed-loop theranostic systems. It covers future challenges in augmented, virtual, and mixed reality, communication modes, energy management, displays, conformity, and data safety. The development of patient-oriented wearable technologies and their incorporation in randomized clinical trials will facilitate the design of safe and effective approaches