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Callus Development and Organogenesis in Cultured Explants of Cowpea (Vigna unguiculata (L.) Walp

Description: Cowpea, Vigna unguiculata (L.) Walp is an excellent source of protein, vitamins and minerals and a major food crop many parts of Africa. Optimal production levels are hampered by insect pests and diseases. Biotechnological techniques such as tissue culture and genetic engineering can aid in the development of varieties with resistance to insect pests and diseases. The objective of this study was to investigate conditions necessary for the development of a reproducible tissue culture system that can be applied to regenerate transformed cells from culture. The in vitro manipulation of cowpea using Murashige and Skoog (MS) medium, auxins and cytokinins resulted in the formation of callus and rhizogenesis. Calli that were formed were separated into six classes based on color and texture. Yellowish friable callus, yellowish compact, soft yellowish callus and green and white were composed of largely vacuolated cells and were non-regenerative. Friable green callus was the most prevalent callus type and could form of roots in some hormone combinations. Green spots were formed on hard compact green callus. The green spots became nodular, forming root primordia and ultimately giving rise to roots. None of the six calli types gave rise to the formation of shoots. Embryogenic callus was induced from cowpea explants cultured on MS medium supplemented with dicamba and picloram. Embryogenic suspension cultures were initiated from callus induced on MS supplemented with 3.0 mg/L dicamba or picloram and conditions for maintenance of embryogenic suspension cultures were evaluated. Somatic embryos were formed in suspension cultures. Attempts to convert and germinate the somatic embryos resulted in the formation of callus or formation of appendages on the somatic embryos or in the death of the embryos. The appendages formed roots on prolonged culture. Further research is needed to determine appropriate optimal conditions for embryo conversion and germination and ultimately plant ...
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Date: December 2004
Creator: Omwenga, George Isanda

Carbachol- and ACPD-Induced Phosphoinositide Responses in the Developing Rat Neocortex

Description: Signal transduction via the phosphoinositide (PI) second messenger system has key roles in the development and plasticity of the neocortex. The present study localized PI responses to individual cortical layers in slices of developing rat somatosensory cortex. The acetylcholine agonist carbachol and the glutamate agonist trans-1-amino-1,3-cyclopentanedicarboxylic acid (ACPD) were used to stimulate PI turnover. The PI responses were compared to the distribution of the corresponding PI-linked receptors in order to investigate the regional ontogeny of PI coupling to receptors in relation to neural development. The method for assessing PI turnover was modified from Hwang et al. (1990). This method images the PI response autoradiographically through the localizaton of [3H]cytidine that has been incorporated into the membrane-bound intermediate, cytidine diphosphate diacylglycerol. In each age group (postnatal days 4-30), carbachol resulted in more overall labeling than ACPD. For both agonists, the response peaked on postnatal day 10 (P10) and was lowest in the oldest age group. The laminar distribution of the carbachol PI response from P4-P16 corresponded fairly well with the laminar distribution of [3H]quinuclidinyl benzilate binding (Fuchs, 1995). However, in the subplate layer the carbachol response was strong while receptor binding was minimal. The carbachol response decreased after postnatal day 10, while the overall levels of receptor binding continued to increase. From P5 - P14, PI-linked metabotropic glutamate receptors are most concentrated in layer IV (Blue et al., 1997), whereas only on P6 was there a correspondingly high ACPD-initiated PI response in this layer. Unlike receptors, the PI response was strong in upper V (P4 - P12) and within layers II/III (P8 - P16). From P4 - P21, the subplate showed relatively high PI labeling compared to receptor binding. The several differences between the distribution of PI response and receptors suggest spatiotemporal heterogeneity of receptor coupling to second messenger systems.
Date: August 2000
Creator: Hartgraves, Morri D.

Carbon Flux in Reservoir Sediments

Description: The central objective of the study was to fractionate sedimenting organic materials according to their source (allochthonous or autochthonous) and ultimately to determine the degree of biodegradability of contributions from either source with particular reference to activities at the mud-water interface.
Date: May 1973
Creator: Newton, Charles Eugene

Cardio-Respiratory Ontogeny and the Transition to Bimodal Respiration in an Air Breathing Fish: Morphological and Physiological Development in Normoxia and Hypoxia.

Description: As selection pressures exist for not only adults, but for every life history stage, it is important to understand how environmental factors shape developing animals. Despite the significance placed on aquatic hypoxia as a driving force in the evolution of air breathing, this is the first known study to examine the effects of hypoxia on cardio-respiratory ontogeny of an air breathing fish. Blue gouramis are obligatory air breathing fish that possess a labyrinth-like structure that serves as the air breathing organ. Gouramis were reared for up to 90 d in normoxia or hypoxia, and morphological and physiological development was observed. Hypoxic larvae had increased lamellar and labyrinth organ surface areas. Bradycardia and increased gill ventilation rates were observed when larvae from either rearing group were briefly exposed to hypoxia. Hypoxic larvae also showed a reduced heart rate and gill ventilation rate in the absence of a hypoxic stimulus, possibly indicative of a more comprehensive, long-term respiratory plasticity. The similarity of routine oxygen consumption between rearing groups suggests that metabolic demand did not change for hypoxic larvae, but that they were more efficient at oxygen acquisition. This is further supported by increased resistance time of hypoxic gouramis to extreme hypoxia. The onset of air breathing was between 20 and 25 d post-fertilization, and was not affected by either rearing or exposure environment. It may be that this behavior is associated with the inability of smaller larvae to successfully overcome water surface tension, rather than with the necessity of aerial respiration at this stage. Hypoxia is commonly experienced by most air breathing fishes, and studies of hypoxia-induced developmental effects may provide critical insights into the evolution of air breathing. The studies presented here provide novel data on the plasticity of cardio-respiratory development of an air breathing fish reared in hypoxia, and can ...
Date: August 2009
Creator: Blank, Tara M.

Cardiorespiratory Responses to Graded Levels of Lower-body Positive Pressure During Dynamic Exercise in Man

Description: Cardiorespiratory responses to incremental dynamic exercise were assessed across four different levels of lower-body positive pressure (LBPP) and, as a separate study, during constant load (i.e constant work rate) exercise below and above each subject's ventilatory threshold (VT), both with and without 45 torr of LBPP.
Date: December 1992
Creator: Williamson, Jon W. (Jon Whitney)

Cardiovascular Fetal Programming in Quail (Colinus virginianus), An Avian Comparative Model

Description: The consequences of early embryonic insults and how they affect subsequent life reflects the emerging concept of "fetal programming". The aim of this project is to study the effects of embryonic insults as they subsequently manifest themselves in adults, with emphasis on the heart and vasculature. My experiments establish that fetal programming operates on the bobwhite quail inducing similar changes as those observed in mammalians and other birds. The quail's fast development provides reliable data in a short period of time than other avian models (e.g. domestic chicken). Data on quail showed a correlation between egg mass and hatchling mass; where small eggs produce small hatchlings but a high mortality made it impractical as a stressor for this study. Hypoxia was used as a stressor during embryonic incubation, where it induced a low hatching weight in quail that was not observable in adult birds. Morphological measurements demonstrated an increased ventricular collagen content and reduced ventricular lumen in birds in adults incubated in hypoxia consistent with hypertension. The hematological analyzes showed few differences indicating organ remodeling instead of hematopoietic compensation. The assessment of vascular reactivity pointed out an impaired endothelium dependent relaxation commonly associated to hypertension in birds and mammals. Fetal programming could be a widespread response to an adverse prenatal environment in endotherms and the resulting data from this work contributes to our understanding of fetal programming in vertebrates and its long term consequences.
Date: December 2016
Creator: Flores Santin, Josele

Cassette Systems for Creating Intergeneric Hybrid ATCases

Description: Cassette systems for creating intergeneric hybrid ATCases were constructed. An MluI restriction enzyme site was introduced at the carbamoylphosphate binding site within the pyrB genes of both Pseudomonas putida and Escherichia coli. Two hybrids, E. coli pyrB polar domain fused with P. putida pyrB equatorial domain and P. putida pyrB polar domain fused with E. coli pyrB equatorial domain, are possible. The intergeneric E. coli-P. putida hybrid pyrB gene was constructed and found to encode an active ATCase which complemented an E. coli Pyr- strain. These hybrids are useful for kinetic and expression studies of ATCase in E. coli.
Date: December 1999
Creator: Simpson, Luci N.

Cell-Free Recovery and Isotopic Identification of Cyanide Degrading Enzymes from Pseudomonas Fluorescens

Description: Cell-free extracts from Pseudomonas fluorescens NCIMB 11764 catalyzed the degradation of cyanide into products that included C02, formic acid, formamide and ammonia. Cyanide-degrading activity was localized to cytosolic cell fractions and was observed at substrate concentrations as high as 100 mM. Two cyanide degrading activities were identified by: (i) the determination of reaction products stoichiometries, (ii) requirements for NADH and oxygen, and (iii) kinetic analysis. The first activity produced CO2 and NH3 as reaction products, was dependent on oxygen and NADH for activity, and displayed an apparent Km for cyanide of 1.2 mM. The second activity generated formic acid (and NH3) pfus formamide as reaction products, was oxygen independent, and had an apparent Km of 12 mM for cyanide. The first enzymatic activity was identified as cyanide oxygenase whereas the second activity consists of two enzymes, a cyanide nitrilase (dihydratase) and putative cyanide hydratase. In addition to these enzymes, cyanide-grown cells were also induced for formate dehydrogenase (FDH), providing a means of recycling NADH utilized by cyanide oxygenase.
Date: December 1995
Creator: Wang, Chien-Sao

Characteristics of Primary Cilia and Centrosomes in Neuronal and Glial Lineages of the Adult Brain

Description: Primary cilia are sensory organelles that are important for initiating cell division in the brain, especially through sonic hedgehog (Shh) signaling. Several lines of evidence suggest that the mitogenic effect of Shh requires primary cilia. Proliferation initiated by Shh signaling plays key roles in brain development, in neurogenesis in the adult hippocampus, and in the generation of glial cells in response to cortical injury. In spite of the likely involvement of cilia in these events, little is known about their characteristics. Centrosomes, which are associated with primary cilia, also have multiple influences on the cell cycle, and they are important in assembling microtubules for the maintenance of the cell’s cytoskeleton and cilia. The cilia of terminally differentiated neurons have been previously examined with respect to length, incidence, and receptors present. However, almost nothing is known about primary cilia in stem cells, progenitors, or differentiated glial cells. Moreover, it is not known how the properties of cilia and centrosomes may vary with cell cycle or proliferative potential, in brain or other tissues. This dissertation focuses first on neurogenesis in the hippocampal subgranular zone (SGZ). The SGZ is one of the few brain regions in mammals that gives rise to a substantial number of new neurons throughout adulthood. The neuron lineage contains a progression of identifiable precursor cell types with different proliferation rates. This present study found that primary cilia were present in every cell type in the neuronal lineage in SGZ. Cilium length and incidence were positively correlated among these cell types. Ciliary levels of adenylyl cyclase type III (ACIII) levels relative to ADP-ribosylation factor-like protein 13b (Arl13b) was higher in neurons than in precursor cells and glia, and also changed with the cell cycle. G-protein coupled receptors, SstR3, MCHR1, and Gpr161 receptors were only found in neuronal cilia. The levels ...
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Date: May 2015
Creator: Bhattarai, Samip Ram

Characterization of a Human 28S Ribosomal RNA Retropseudogene and Other Repetitive DNA Sequence Elements Isolated from a Human X Chromosome-Specific Library

Description: Three genomic clones encompassing human DNA segments (designated LhX-3, LhX-4, and LhX5) were isolated from an X chromosome-specific library and subjected to analysis by physical mapping and DNA sequencing. It was found that these three clones are very rich in repetitive DNA sequence elements and retropseudogenes.
Date: May 1994
Creator: Wang, Suyue

Characterization of Arthrobacter Globiformis Aspartate Transcarbamylase Concentrations of Substrates

Description: This thesis consists of one major section with two subsections. The first subsection investigates the activity of Arthrobacter globiformis aspartate transcarbamylase's specific activity with increasing concentrations of the enzyme's substrate. Dihydroorotase (DHOase) activity was also measured with increasing concentrations of the substrate dihydroorotate. The second subsection collected data in order to classify the enzyme, resulting in a classification into the category of class A ATCases with bifunctional ATCase-DHOase complexes. The thesis provides evidence to broaden understanding of the ATCase and DHOase enzymes for members of the family that Arthrobacter belongs to.
Date: December 2012
Creator: Wright, Jackie

Characterization of Aspartate Transcarbamoylase and Dihydroorotase in Moraxella Catarrhalis

Description: Bacterial aspartate transcarbamoylases (ATCase's) are divided into three classes that correspond to taxonomic relationships within the bacteria. The opportunistic pathogen Moraxeila catarrhalis has undergone several reclassifications based on traditional microbiological criteria. The previously uncharacterized ATCase from M. catarrhalis was purified to homogeneity and its chemical properties characterized. The ATCase from M. catarrhalis is a class C ATCase with an apparent molecular mass of 480-520 kDa. The M. catarrhalis ATCase is a dodecomer composed of six 35 kDa polypeptides and six 45 kDa polypeptides. The enzyme has an unusually high pH optimum of greater than pH 10. The enzyme exhibited hyperbolic kinetic with a Km for aspartate of 2 mM. A single, separate 78 kDa dihydroorotase from M. catarrhalis was identified and it was not associated with ATCase. These data support the reclassification of M. catarrhalis out of the Neisseriaceae family.
Date: May 1998
Creator: Fowler, Michael A. (Michael Allen), 1961-

Characterization of cDNA and Genomic Clones for a Palmitoyl-acyl Carrier Protein Thioesterase and an Osmotin-Like PR5 Protein in Gossypium Hirsutum.

Description: Putative cotton cDNA clones and cognate genomic clones for a palmitoyl-acyl carrier protein (ACP) thioesterase (PATE) and an osmotin-like pathogenesis-related 5 (PR5) protein have been isolated and characterized. PATE is a class B fatty acid thioesterase with specificity for saturated long-chain fatty acids such as palmitate, and is implicated as a key enzyme to be targeted for regulation of fatty acid synthesis in order to alter cotton seed oil profiles. A nearly full-length 1.7-kb cDNA clone was isolated using a hybridization probe derived from an Arabidopsis PATE cDNA clone designated TE 3-2. A 17-kb genomic segment encompassing the PATE gene was also isolated, which has six exons and five introns with high sequence identity with other FatB cDNA/gene sequences. The deduced PATE preprotein amino acid sequence of 413 residues has putative signal sequences for targeting to the chloroplast stroma. PR5 proteins called osmotins are made in response to fungal pathogen stress or osmotic stress (water deprivation or salt exposure). Osmotins may actually form pores in fungal membranes, leading to osmotic rupture and destruction of the fungal cells. A cotton osmotin-like PR5 cDNA insert of 1,052 base-pairs was isolated and shown to encode a preprotein of 242 amino acids and is predicted to be secreted to the extracellular matrix as a neutral isoform. The deduced amino acid sequence has 16 cysteine residues that are highly conserved in osmotin-like proteins and are important in stabilizing the three-dimensional structure seen in thaumatin, zeamatin, and PR5-d. The intronless cognate cotton genomic clone has two putative ethylene response elements (GCC boxes) found in other PR5 gene promoter regions, as well as several tentative promoter/enhancer elements possibly involved in spatial/temporal gene expression.
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Date: May 2002
Creator: Yoder, David W.

Characterization of Infection Arrest Mutants of Medicago Truncatula and Genetic Mapping of Their Respective Genes.

Description: In response to compatible rhizobia, leguminous plants develop unique plant organs, root nodules, in which rhizobia fix nitrogen into ammonia. During nodule invasion, the rhizobia gain access to newly divided cells, the nodule primordia, in the root inner cortex through plant-derived cellulose tubes called infection threads. Infection threads begin in curled root hairs and bring rhizobia into the root crossing several cell layers in the process. Ultimately the rhizobia are deposited within nodule primordium cells through a process resembling endocytosis. Plant host mechanisms underlying the formation and regulation of the invasion process are not understood. To identify and clone plant genes required for nodule invasion, recent efforts have focused on Medicago truncatula. In a collaborative effort the nodulation defect in the lin (lumpy infections) mutant was characterized. From an EMS-mutagenized population of M. truncatula, two non-allelic mutants nip (numerous infections with polyphenolics) and sli (sluggish infections) were identified with defects in nodule invasion. Infection threads were found to proliferate abnormally in the nip mutant nodules with only very rare deposition of rhizobia within plant host cells. nip nodules were found to accumulate polyphenolic compounds, indicative of a host defense response. Interestingly, nip was also found to have defective lateral root elongation suggesting that NIP has a role in both nodule and lateral root development. NIP was found to map at the upper arm of chromosome 1. In sli, infection threads were observed to bring rhizobia from infection threads to newly divided nodule primordium cells in the roots inner cortex. Polyphenolic accumulation in sli nodule/bumps was found. Lateral roots in sli were found to be clustered at the top of the root, indicating that sli like nip may be defective in lateral root development.
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Date: May 2005
Creator: Veereshlingam, Harita

A Characterization Of Jackson Blue Spring, Jackson County, Florida

Description: Jackson Blue is a first magnitude spring in the karst terrane of northeast Florida. Previous studies have identified inorganic fertilizer as the source of high nitrate levels in the spring. Agricultural land use and karst vulnerability make Jackson Blue a good model for conservation concerns. This work offers an aggregation of studies relating to the springshed, providing a valuable tool for planning and conservation efforts in the region. An analysis of nitrate levels and other water quality parameters within the springshed did not reveal significantly different values between agricultural and forested land use areas. Confounding factors include: high transmissivity in the aquifer, interspersed land use parcels, and fertilizer application in forested areas due to commercial pine stand activity.
Date: December 2011
Creator: Reiser, Cora

A Characterization of Liver Glyoxalase I From Normal Mice and Mice Bearing Lymphosarcoma

Description: The purpose of this investigation was (1) to isolate and purify glyoxalase I from the livers of normal DBA/lJ mice and the livers from mice bearing a lymphosarcoma tumor; and (2) to determine, at least with respect to glyoxalase I, if the tumor has an effect on the chemical properties or structure of macromolecules in an organ removed from tumor locale and not histologically affected by its presence.
Date: August 1970
Creator: Strzinek, Robert Alfred

Characterization of Pyrimidine Biosynthesis in Pseudomonas putida Using Mutant and Wild Type Strains

Description: The biosynthesis of pyrimidines in Pseudomonas putida was investigated. In this study, pyrimidine requiring mutants were isolated by conventional mutagenesis and enrichment. The strains required exogenously supplied pyrimidines for growth and were found by enzyme assays to be deficient for the product of the pyrB gene encoding the enzyme aspartate transcarbamoylase. None of the intermediates of the pathway could supply the auxotrophic requirement of the strain; only preformed pyrimidines, metabolized via salvage pathways could suffice. Pyrimidine limitation in the mutant caused a slight but significant fifty per cent increase in expression of all the de novo biosynthetic enzymes. Pyrimidine starvation's effect on nucleotide pool levels was examined in the mutant and caused a marked swelling of the purine nucleotide pools.
Date: August 1991
Creator: Chang, Mingren

Characterization of Triclocarban, Methyl- Triclosan, and Triclosan in Water, Sediment, and Corbicula Fluminea (Müller, 1774) Using Laboratory, in Situ, and Field Assessments

Description: In the last decade emerging contaminants research has intensified in a bid to answer questions about fate, transport, and effects as these chemicals as they get released into the environment. The chemicals of interest were the antimicrobials; triclocarban (TCC) and triclosan (TCS), and a metabolite of triclosan, methyl triclosan (MTCS). This research was designed to answer the question: what is the fate of these chemicals once they are released from the waste water treatment plant into receiving streams. Three different assessment methods; field monitoring, in-situ experiments, and laboratory studies were used to answer the overall question. TCS, TCC, and MTCS levels were measured in surface water, sediment and the Asiatic clam Corbicula fluminea. Field studies were conducted using four sites at Pecan Creek, Denton TX. Levels of all three chemicals in clams were up to fives orders of magnitude the water concentrations but an order of magnitude lower than in sediment. Highest sediment levels of chemicals were measured in samples from the mouth of Pecan Creek (highest organic matter). TCC was the most and TCS was the least accumulated chemicals. In-situ and lab studies both indicated that uptake of these chemicals into the clams was very rapid and measurable within 24hours of exposure. The after clams were transferred into clean water most of the compounds were depurated within 14 days.
Date: May 2011
Creator: Edziyie, Regina E.

Characterizing Spontaneous Neurophysiological Activity with Measures of Statistical Serial Dependence: a Summary Statistic and an Extension of the Joint Interval Histogram

Description: Two measures which indicate statistical serial dependence were evaluated. The n-dimensional Average Stored Information index (ndASI) is a measure of conditional information, which compares the entropies of higher order conditional distributions to estimate average statistical serial dependence. The generalized ranked joint interval histogram (RJIH-o) is a new nonparametric graphical analysis method. It extends the joint interval histogram by depicting longer interval sequences and can be interpereted precisely analagously to the joint interval histogram. The generalized ranked joint interval histogram correctly represents independence in a Poisson process model and statistical serial dependence in a directionally reinforced Markov model. The generalized ranked joint interval histogram correctly depicts the underlying periodic and strange attractors in a standard map model. Both measures can be used to effectively analyze interspike interval sequences from spontaneous neurophsyiological activity effectively.
Date: August 1994
Creator: Weil, Jon C. (Jon Christopher)

Characterizing the Municipal Solid Waste Stream in Denton, Texas

Description: Forty-two commercially collected dumpsters from Denton’s Municipal Solid Waste Stream were emptied, sorted and weighed to characterize the material types and make preliminary recycling policy recommendations. The general composition of Denton’s solid waste stream was not significantly different from the composition of the nation’s solid waste stream. Fifty-eight percent of the observed waste stream was recyclable. Paper made up the largest portion of recyclable materials and the "grocery" source category had more paper than any of the other five categories. Based on these findings, an incrementally aggressive approach is recommended to reduce certain types of wastes observed in the waste stream. This would include a Pay-As-You-Throw Program followed by an Intermediate Processing Center that can be converted to a Materials Recovery Facility.
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Date: August 2000
Creator: Brady, Patricia D.

Chemotactic Response of Lumbricus terrestris Coelomocytes to Larval and Adult Stages of Rhabditis pellio

Description: Experiments were performed to assess the suitability of Rhabditis pellio, a nematode found in earthworms, as a challenge organism for use in development of a biomarker assay to determine the potential of chemicals to suppress the immunocompetence of the non-specific immune system. To accomplish this goal, information on the life cycle of R. pellio was determined; including effects of incubation time and temperature on growth rates; along with information on the immune response elicited in the earthworm, Lumbricus terrestris. Immune parameters measured were coelomocyte migration toward and attachment to R. pellio larvae and adults. Preliminary background information showed that R. pellio has potential as a challenge organism for development of a biomarker assay.
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Date: December 1999
Creator: Medrano, Jennifer Centurion

Chronic Hypoxia and Hyperoxia Modifies Morphology and Vegf Expression of the Lungs of the Developing Chicken (Gallus Gallus Domesticus)

Description: This study determines effects of oxygen levels on morphology and VEGF expression of developing chicken lungs following incubation in normoxia (21% O2), hypoxia (15% O2) or hyperoxia (30% O2), until developmental days 16 or 18. Lung morphology was assessed using light microscopy, while VEGF expression was determined with ELISA. In hypoxia, the proportion of parabronchial tissue and parabronchi including lumina increased from day 16 to 18 (61 to 68% and 74.2 to 82.2%, respectively). Non-parabronchial tissue was higher in hypoxia than in hyperoxia on day 16 (26 to 20%). However, by day 18, there were no differences between groups. VEGF expression was 33% higher in hypoxia than in hyperoxia on day 16 (736 vs. 492 pg/ml). On day 18, VEGF expression was 43% higher in hyperoxia than in normoxia (673 to 381pg/ml), and remained elevated by 40% in hypoxia over normoxia (631 pg/ml). VEGF may be a mechanism by which parabronchial tissue is stimulated from day 16 to 18 following exposure to chronic hypoxia.
Date: December 2012
Creator: Lewallen, Melissa Anjanette

Chronic Ventricular Sympathectomy : Effects on Myocardial Metabolism

Description: Chronic ventricular sympathectomy elicits changes in the coronary circulation, myocardial oxygen consumption and size of infarction resulting fromcoronary occlusion. These changes indicate a change occurring in the basic metabolism of the heart in response to the removal of its sympathetic nervous input. This hypothesis was tested using two groups of dogs, a shamoperated control and a ventricular sympathectomized group. The sympathectomy procedure was an intrapericardial surgical technique which selectively removes ventricular sympathetic input. Four weeks after surgery, left ventricular tissue samples were obtained and rapidly frozen to -80°C. Selected metabolic variables were then compared between the two groups.
Date: August 1993
Creator: Adix Longlet, Nancy J.