476 research outputs found
A Long-Term Analysis of Changes in Farm Size and Financial Performance
This paper examined the changing structure of farms in Kansas. Specifically, changes in farm size, farm type, financial performance, and economies of size were examined using five-year moving averages from 1973 to 2007. Convergence analysis was used to determine whether small farms are catching up to larger farms or whether the difference in performance between these two groups of farms was widening. Results suggested that the gaps between the small farms and large farms have widened.Economies of Size, Financial Performance, Farm Management, Production Economics, D21,
Marginal Propensity to Consume for a Sample of Kansas Farms
This paper examined the marginal propensity to consume (MPC) for a sample of Kansas farms. Sensitivity of estimated MPCs to the use of accrual net farm income, net cash farm income, and the inclusion of off-farm income was also examined. Results yielded a range of short-run MPCs from 0.011 to 0.015. Statistical tests suggested that the income coefficients used to compute short-run MPCs were not statistically different.Farm Consumption, Habit Persistence, Agricultural Finance, Farm Management, E21,
Thrombin Effects on Cultured Nerve Cells: Clinical Implications and Evidence for a Novel Mechanism of Neuronal Activation a
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75548/1/j.1749-6632.1986.tb34592.x.pd
Modulation of Neuronal Signal Transduction Systems by Extracellular ATP
The secretion of ATP by stimulated nerves is well documented. Following repetitive stimulation, extracellular ATP at the synapse can accumulate to levels estimated to be well over 100 Μ M. The present study examined the effects of extracellular ATP in the concentration range of 0.1–1.0 m M on second-messenger-generating systems in cultured neural cells of the clones NG108-15 and NIE-115. Cells in a medium mimicking the physiological extracellular environment were used to measure 45 Ca 2+ uptake, changes in free intracellular Ca 2+ levels by the probes aequorin and Quin-2, de novo generation of cyclic GMP and cyclic AMP from intracellular GTP and ATP pools prelabeled with [ 3 H]guanosine and [ 3 H]adenine, respectively, and phosphoinositide metabolism in cells preloaded with [ 3 H]inositol and assayed in the presence of LiCI. Extracelluar ATP induced a concentration-dependent increase of 45 Ca 2+ uptake by intact cells, which was additive with the uptake induced by K + depolarization. The increased uptake involved elevation of intracellular free Ca 2+ ions, evidenced by measuring aequorin and Quin-2 signals. At the same concentration range (0.1–1.0 m M ), extracellular ATP induced an increase in [ 3 H]cyclic GMP formation, and a decrease in prostaglandin E 1 -stimulated [ 3 H]cyclic AMP generation. In addition, extracellular ATP (1 m M ) caused a large (15-fold) increase in [ 3 H]inositol phosphates accumulation, and this effect was blocked by including La 3+ ions in the assay medium. In parallel experiments, we found in NG 108–15 cells surface protein phosphorylation activity that had an apparent K m for extracellular ATP at the same concentration required to produce half-maximal effects on Ca 2+ uptake. Extracellular ATP at concentrations that can be produced in the synaptic cleft by repetitive stimulation but not during routine transmission can thus initiate a unique chain of events, which may play a role in the induction of long-term adaptive changes in neuronal function.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65952/1/j.1471-4159.1988.tb13263.x.pd
Uptake by neuroblastoma cells of glucosylceramide, glucosylceramide glucosidase, its stimulator protein, and phosphatidylserine
Serum-free cultured neuroblastoma cells (clone NIE-115) have been shown to absorb emulsified glucosylceramide, glucosylceramide glucosidase, an activator protein for the enzyme, and phosphatidylserine from a synthetic medium. Uptake of the enzyme was augmented by phosphatidylserine, and vice versa. Uptake of the enzyme-lipid complex was further augmented by the activator protein. It appears likely that the activator forms a complex only with the enzyme-lipid complex, not with the individual components. Two uptake mechanisms for the enzyme seem to be involved, one of which (the complex with activator proteins and acidic lipid) is sensitive to mannosyl phosphate groups. Hydrolysis of absorbed glucosylceramide was slow unless the medium was supplemented with the acidic phospholipid or glucosidase. The most rapid disappearance of stored glycolipid took place when the ternary mixture was added to the cell medium, enzyme + activator protein + phosphatidylserine. These findings may be relevant to enzyme replacement therapy for Gaucher disease.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26097/1/0000173.pd
Amitriptyline supersensitizes a central cholinergic mechanism
The withdrawal of tricyclic antidepressants produces symptoms characteristic of cholinergic overdrive states. The authors previously proposed that these states are the consequence of the pharmacological induction of cholinergic system supersensitivity by chronic treatment with antidepressants, combined with a reduction in the plasma level of a competitive muscarinic receptor antagonist when the dose of a tricyclic is decreased. This is consistent with the facts that all tricyclic antidepressants are antimuscarinic agents and that classical antimuscarinic compounds, such as scopolamine, up-regulate and supersensitize muscarinic cholinergic systems. The authors present evidence that chronic treatment with amitriptyline supersensitizes a central cholinergic mechanism. Core body temperature is subject to influence by a central (hypothalamic) muscarinic mechanism, which is rendered supersensitive to cholinomimetic challenge by treatment with scopolamine. The authors telemetrically measured the hypothermic responses of adult male rats to various doses of the muscarinic agonist oxotremorine before and in the course of chronic treatment with amitriptyline. Treatment with amitriptyline resulted in marked enhancement of the cholinomimetic-induced hypothermia. Methylscopolamine nitrate, a peripherally active antimuscarinic agent, did not block the hypothermic response to oxotremorine, whereas scopolamine, a centrally active antimuscarinic compound, did. This study indicates that the chronic administration of amitriptyline can produce supersensitivity of a central muscarinic cholinergic mechanism. Clinical and theoretical implications of this finding are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26759/1/0000311.pd
Stress induces supersensitivity of a cholinergic system in rats
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26067/1/0000141.pd
Muscarinic receptor-stimulated Ca2+ signaling and inositol lipid metabolism in avian salt gland cells
Activation of muscarinic cholinergic receptors was studied by measuring agonist-stimulated inositol lipid turnover and changes in [Ca2+]i in dissociated salt gland secretory cells. Carbachol stimulation of quin2-loaded cells results in a sustained 4-fold increase in [Ca2+]i, while incorporation of [32P]Pi into phosphatidylinositol (PI) and phosphatidate are similarly increased. [3H]Inositol phosphates, measured in the presence of Li+, increased 13-fold. The stimulated increment in [Ca2+]i required extracellular Ca2+, whereas [3H]inositol phosphate accumulation was independent of external Ca2+. Dose-response curves for carbachol-induced increments in [Ca2+]i, PI labeling, and labeled inositol phosphate release are similar, with EC50 values of 6, 4.5 and 8 [mu]M, respectively. Dissociation constants for atropine vs. the quin2 and phospholipid responses are 0.59 +/- 0.3 nM and 0.48 +/- 0.28 nM, respectively. These cells thus provide a model system for the study of non-exocytotic secretion as a consequence of stimulated inositol lipid turnover.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25973/1/0000039.pd
The Victorian Newsletter (Fall 1993)
The Victorian Newsletter is sponsored for the Victorian Group of Modern Language Association by Western Kentucky University and is published twice annually.Eros and Logos in Some Fairy Tales by Oscar Wilde: A Jungian Interpretation / Clifton Snider -- "The Central Truth": Phallogocentrism in Aurora Leigh / Patricia Thomas Srebnik -- "I Magnify My Office": Christina Rossetti's Authoritative Voice in Her Devotional Prose / Joel Westerholm -- The Sterile Star of Venus: Swinburne's Dream of Flight / Peter Anderson -- Bringing to Earth the "Good Angel of the Race" / Michael Schiefelbein -- The Flawed Craft of A. E. Housman / A. R. Coulthard -- The Physiological Determinism Debate in Oscar Wilde's The Picture of Dorian Gray / Terri A. Hasseler -- Overdetermined Allegory in Jekyll and Hyde / Cyndy Hendershot -- Books Received -- Group New
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