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Articles 2791 - 2820 of 3160

Full-Text Articles in Life Sciences

An Evaluation Of A Pilot Interpretive Program For National Forest Recreation Areas In East Texas, Ronda Elain Sutphen May 1994

An Evaluation Of A Pilot Interpretive Program For National Forest Recreation Areas In East Texas, Ronda Elain Sutphen

Electronic Theses and Dissertations

A visitor survey was conducted at Ratcliff and Double Lake National Forest Recreation Areas to evaluate visitor characteristics and the effectiveness of interpretive services as a management tool. Two hundred eighty-two campers completed the visitor survey. A one hundred percent sample was attempted at both recreation areas every Sunday morning during July and August of 1991. Data from both recreation areas were analyzed and compared in order to determine any significant differences between visitors in each recreation area and also between visitors who attended or did not attend interpretive programs.

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Characteristics Of Milk And Reduced Fat Cheddar Cheese From Cows Fed Extruded Soybeans And Niacin, Matthew Ryan Lentsch Jan 1994

Characteristics Of Milk And Reduced Fat Cheddar Cheese From Cows Fed Extruded Soybeans And Niacin, Matthew Ryan Lentsch

Electronic Theses and Dissertations

Today's consumers are demanding food products that are "low-fat", "reduced fat", "high in -unsaturated fatty acids", and "low cholesterol". This trend in food product selection is at the advice of many health professionals. Current health recommendations are to lower the dietary intake of fat, especially saturated fat. In 1992, total dairy sales accounted for over 10% of total food sales (Milk Industry Foundation, 1993). Since dairy products are perceived as being hypercholesterolemic, a market exists for dairy products which are "lower in fat" and/or "lower in saturated fat". It is said that "consumer perception is marketing reality", and because of …

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A Characterization Of Extractable, Hydroxylated Fatty Acid Bearing Components In Legionella Pneumophila, Jonathan R. Lane Dec 1993

A Characterization Of Extractable, Hydroxylated Fatty Acid Bearing Components In Legionella Pneumophila, Jonathan R. Lane

Electronic Theses and Dissertations

Extraction of the lipids of Legionella pneumophila yields phases unlike those produced from other Gram-negative bacteria. A viscous interface forms between the aqueous (wash) and organic phases. More than half of the hydroxylated fatty acids were found distributed between the aqueous phase and the interfacial material, fractions in which such constituents have not been reported in other Gram-negative species. It was further observed that after the material from the aqueous/interfacial phase was dissolved in methanol or chloroform/methanol (2:1 (V/V)), the addition of acetone would create a white, flocculent precipitate. Analyses showed that the supernatant contained fatty acids that were nonhydroxylated …

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A Molecular Basis For Erythromycin Sensitivity And Resistance In Escherichia Coli, Harold S. Chittum Dec 1993

A Molecular Basis For Erythromycin Sensitivity And Resistance In Escherichia Coli, Harold S. Chittum

Electronic Theses and Dissertations

The effect of erythromycin on the 50S ribosomal subunit during cell growth has been extensively investigated. Sucrose density gradient analysis of ribosomes formed in the presence and absence of the drug revealed a 50S specific assembly defect is partially responsible for erythromycin's inhibitory effects on wild type cells. Examination of two erythromycin-resistant mutants of E. coli (N281 and N282) revealed that mutant N281 (L22 mutant) but not N282 (L4 mutant) was assembly defective in the presence of the drug, although only at much higher drug concentrations (300 ug/ml vs. 75 ug/ml for wild type cells). The altered genes from each …

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Nitric Oxide Production: A Mechanism For Inhibition Of Chlamydia Trachomatis Replication, Bojun Chen Dec 1993

Nitric Oxide Production: A Mechanism For Inhibition Of Chlamydia Trachomatis Replication, Bojun Chen

Electronic Theses and Dissertations

Chlamydia trachomatis (CT) replicates in macrophages, but is inhibited by IFN-$\gamma$ or LPS. IFN-$\gamma$ and/or LPS induced nitrite production in mouse peritoneal macrophages, macrophage cell lines (RAW264.7 and J774A.1) and McCoy cells. Kinetic studies indicated that peak production occurred 48 hours post-treatment. CT infection itself was insufficient to induce nitrite production, but resulted in enhancement of nitrite production in IFN-$\gamma$-treated cells. Treatment with IFN-$\gamma$ or LPS resulted in significant inhibition of CT replication in these cells. Strong correlation between nitrite production and inhibition of CT replication was observed in RAW264.7 and J774A.1 cells (correlation coefficients: $-$0.93 and $-$0.94, p $<$ 0.001). N$\sp{\rm g}$- monomethyl-L-arginine (L-NMMA) specifically inhibited nitrite production and partially reversed inhibition of CT replication in macrophage cell lines. NOS mRNA was measured in RAW264.7 cells by Northern blot and Dot blot hybridization. Strong correlation between NOS mRNA expression and inhibition of CT replication (correlation coefficient: $-$0.97, p $<$ 0.05) was observed. Anti-TNF-$\alpha$ antibody completely neutralized the biological activity of TNF-$\alpha$ secreted by LPS-treated RAW264.7 cells, yet the antibody neither reduced nitrite production nor restored CT replication. Combination of the antibody and L-NMMA significantly enhanced restoration of CT replication. In peritoneal macrophages, inhibition of CT replication induced by IFN-$\gamma$ was partially restored by L-NMMA or anti-TNF-$\alpha$ antibody. In McCoy cells, inhibition of CT replication induced by IFN-$\gamma$ and LPS was not significantly restored by L-NMMA. Great restoration of CT replication by 1 mM L-NMMA was observed in LPS-treated J774A.1 cells (31%), but not in IFN-$\gamma$-treated cells (5%). Our data indicate that (1) NO production is one of the mechanisms for inhibition of CT replication in IFN-$\gamma$-activated peritoneal macrophages and RAW264.7 cells; (2) NO plays a significant role in CT inhibition in LPS-treated macrophage cell lines, but not peritoneal macrophages; (3) TNF-$\alpha$ may be associated with inhibition, but the mechanism(s) may not involve NO production; (4) NO production may not be the mechanism for CT inhibition in McCoy cells treated with IFN-$\gamma$ and LPS.

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Co-Sensitization Of Dopamine And Serotonin Receptors Occurs In The Absence Of A Change In The Dopamine D1 Receptor Complex After A Neonatal 6-Ohda Lesion, Li Gong Dec 1993

Co-Sensitization Of Dopamine And Serotonin Receptors Occurs In The Absence Of A Change In The Dopamine D1 Receptor Complex After A Neonatal 6-Ohda Lesion, Li Gong

Electronic Theses and Dissertations

To test whether SKF 38393 could ontogenetically sensitize dopamine (DA) D$\sb1$ receptors and whether this sensitization would be associated with biochemical changes, intact and neonatal 6-hydroxydopamine (6-OHDA)-lesioned rats (200 $\mu$g i.c.v.) were treated daily from birth with SKF 38393 (3.0 mg/kg i.p. x 28 days) or its vehicle. In DA D$\sb1$ neonatally sensitized 6-OHDA rats, enhanced locomotor responses were observed with the first SKF 38393 challenge dose (3.0 mg/kg i.p.) at 6 weeks. This response increased further with weekly SKF 38393 treatments. Enhanced stereotyped behaviors were seen in both lesioned and sensitized rats at 8 weeks. There was no change …

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Unusual Structure Of A Human Middle Repetitive Dna, Duminda D. Ratnasinghe Dec 1993

Unusual Structure Of A Human Middle Repetitive Dna, Duminda D. Ratnasinghe

Electronic Theses and Dissertations

The L2Hs sequences are a polymorphic, interspersed, middle repetitive DNA family unique to human genomes. Genomic fingerprinting indicates that these DNAs vary from one individual to another and between tissues of the same individual. Sequence analysis reveals that they are AT-rich (76%) and contain many unusual sequence arrangements (palindromes, inverted and direct repeats). These sequence properties confer on the L2Hs elements the potential to fold into non-B-form structures, a characteristic of recombination hot spots. To test this hypothesis carbodiimide, osmium tetroxide and S$\sb1$ nuclease were used as single-strand specific probes to study a recombinant plasmid, pN6.4.39, containing a single L2Hs …

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Mechanisms Of T Cell-Mediated Macrophage Activation: Role Of Antigen Specific And Antigen Nonspecific Cognate Interactions, Xiang Tao Jun 1993

Mechanisms Of T Cell-Mediated Macrophage Activation: Role Of Antigen Specific And Antigen Nonspecific Cognate Interactions, Xiang Tao

Electronic Theses and Dissertations

Macrophages play an important role in host antimicrobial immunity and in non-septic inflammatory reactions. Most studies on macrophage activation have focused on the roles of the T cell-produced cytokine, interferon-$\gamma$ (IFN$\gamma)$ and bacterial product, lipopolysaccharide (LPS). T cell-macrophage interaction is a critical step in initiating both specific and nonspecific immune responses to antigenic stimulation. The current study examines the role of cognate T cell-macrophage interaction in activation of macrophage effector functions and induction of macrophage early activation gene expression. Viable resting T$\sb{\rm H}$2 clone cells can activate IFN$\gamma$-primed macrophages to produce reactive nitrogen intermediates (RNI) or express cytostatic activity. The …

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Human Lung Mast Cell Tryptase Isozymes: Separation And Examination Of Structural And Functional Differences, Susan S. Little May 1993

Human Lung Mast Cell Tryptase Isozymes: Separation And Examination Of Structural And Functional Differences, Susan S. Little

Electronic Theses and Dissertations

Tryptases are trypsin-like enzymes found in mast cell granules. Although in vivo substrates have not been positively identified, tryptases cleave a limited number of potential physiological substrates in vitro, including high molecular weight kininogen (HMWK) and vasoactive intestinal peptide (VIP). Purified human lung mast cell tryptase (HLT) apparently exists as a tetramer with an M$\sb{\rm r}$ of 135-144 kDa by gel filtration, whereas SDS-PAGE yielded two bands of M$\sb{\rm r}$ 29 Kda and 33 Kda. Tryptases are resistant to inhibition by most natural trypsin inhibitors and display some affinity for heparin. The existence of tryptase isozymes has been implied from …

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Probing Protein-Protein Interactions Among Proteins Of A Nonaggregated Fatty Acid Synthetase From Euglena Gracilis Variety Bacillaris, Sande G. Williams May 1993

Probing Protein-Protein Interactions Among Proteins Of A Nonaggregated Fatty Acid Synthetase From Euglena Gracilis Variety Bacillaris, Sande G. Williams

Electronic Theses and Dissertations

Enoyl-acyl carrier protein (ACP) reductase from chloroplast nonaggregated fatty acid synthetase (FAS) of Euglena gracilis variety bacillaris was purified to a single band on a denaturing polyacrylamide gel. The enzyme was partially characterized with respect to substrate specificity, reduced nucleotide requirement, and the effect of ACP and Ca$\sp{++}$ on enzyme activity. Antibodies against the purified protein were raised in hens and isolated from eggs. ACP was purified from Euglena in yields of about 1mg/100g (wet weight) of cells. Antibodies were raised against the purified protein. ACP antibodies inhibited the Euglena chloroplast FAS using Euglena or E. coli ACP as a …

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A Preliminary Preview Of Compensatory Forest Plantation In Peninsular Malaysia, Tuck Chin Dec 1992

A Preliminary Preview Of Compensatory Forest Plantation In Peninsular Malaysia, Tuck Chin

Electronic Theses and Dissertations

Projections of supply and demand for timber appear to indicate a domestic shortage in Peninsular Malaysia by the year 2000. Timber shortage will result in loss of foreign exchange, retrenchment of timber workers, inflate prices and depress construction and housing industries. Compensatory Forest Plantation Program (CFPP) is one of the methods taken by the Malaysian Government to avert this impending crisis. CFPP was officially launched in 1983, in four States of Peninsular Malaysia. By 1989, forest plantations totaling 36,874 hectares were established. A final analysis of CFPP is premature, as the program is only in its seventh year of a …

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The Effect Of Trimethyltin On The Cholinergic System Of The Rat Hippocampus, Richard L. Cannon Dec 1992

The Effect Of Trimethyltin On The Cholinergic System Of The Rat Hippocampus, Richard L. Cannon

Electronic Theses and Dissertations

Trimethyltin (TMT) is a neurotoxin occurring in the environment. Exposure to (TMT) is known to destroy specific neuronal components of the hippocampus in the rat and to cause clinical symptoms in exposed humans, including mnemonic deficits, that indicate hippocampal involvement. In addition to hippocampal cell loss TMT causes significant increases in cholinergic markers such as acetylcholinesterase (AChE) stain density and choline acetyltransferase (ChAT) activity in the hippocampus of rats. However, despite these observations the effect of TMT on hippocampal cholinergic system has not been investigated in detail. The purpose of the present study was to elucidate more fully the consequences …

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Changes In Intracellular Chloride During Osmotic Stress And L-Alanine Uptake In Mouse Hepatocytes, Kening Wang Oct 1992

Changes In Intracellular Chloride During Osmotic Stress And L-Alanine Uptake In Mouse Hepatocytes, Kening Wang

Electronic Theses and Dissertations

A stable intracellular ionic environment is necessary for hepatocytes to function normally. Thus, during hypotonic shock or L-alanine uptake, hepatocytes swell and then exhibit a regulatory volume decrease (RVD), which comprises an increase in K$\sp+$ conductance (G$\sb{\rm K}$), an increased K$\sp+$ efflux, and a hyperpolarization of transmembrane potential (V$\sb{\rm m}$). Since hepatocyte intracellular Cl$\sp-$ has been demonstrated to distribute passively with V$\sb{\rm m}$, this study is designed to test the hypothesis that the hypotonic shock- or L-alanine uptake-induced hyperpolarization of V$\sb{\rm m}$ might provide an electromotive force for the efflux of hepatocyte intracellular Cl$\sp-$, which in turn would contribute osmotically …

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Molecular And Cellular Analysis Of Chlamydia Trachomatis: Persistence And Reactivation, Kimberly R. Tau May 1992

Molecular And Cellular Analysis Of Chlamydia Trachomatis: Persistence And Reactivation, Kimberly R. Tau

Electronic Theses and Dissertations

Chlamydia trachomatis (CT) is the most prevalent sexually-transmitted infection in the United States. It has been suggested that CT infections can become latent. This has not been substantiated. CT persistence was examined at the molecular and cellular level in vitro and in vivo. Penicillin treatment of CT in vitro results in abnormal inclusions and reduced recovery of infectious CT. Penicillin did not inhibit initial stages of infection, but did downregulate CT rRNA levels after 25 hours post-inoculation (p.i.). DNA amplification was employed to differentiate between a resolved infection and a persistent one. Utilizing a primer pair that amplified a 144 …

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Population Status And Characteristics Of Macrhybopsis Gelida, Platygobio Gracilis And Rhinichthys Cataractae In The Missouri River Basin, Selena J. Werdon Jan 1992

Population Status And Characteristics Of Macrhybopsis Gelida, Platygobio Gracilis And Rhinichthys Cataractae In The Missouri River Basin, Selena J. Werdon

Electronic Theses and Dissertations

Few sturgeon chub (Macrhybopsis gelida: Cyprinidae) have been collected in the last decade, therefore their status, habitat selection and morphology were investigated at 172 previous collection sites. Data on two ecologically similar species, Platygobio gracilis and Rhinichthys cataractae, were also collected. Macrhvbopsis gelida were collected at 28 sites on the Powder River (n = 158) in Wyoming and Montana, and at one site on the Yellowstone River (n = 1) in Montana. Age-I, Age-II and Age-III M. gelida were collected. Specimens were 37 to 95 mm in total length. Macrhvbopsis gelida were ripe in mid-June, at water temperatures of 18.3-22. …

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Characterization Of Two Temperature-Sensitive Mutants Of Escherichia Coli Exhibiting An Altered L22 Ribosomal Protein, Bonnie A. Burnette-Vick Aug 1991

Characterization Of Two Temperature-Sensitive Mutants Of Escherichia Coli Exhibiting An Altered L22 Ribosomal Protein, Bonnie A. Burnette-Vick

Electronic Theses and Dissertations

Analysis of E. coli strains SK1047 and SK1048 have shown them to be temperature-sensitive, protein-synthesis deficient. An alteration in ribosomal protein L22 was detected in both strains using two dimensional gel electrophoresis. Protein L22 was purified from both strains by reversed phase high performance liquid chromatography and from two dimensional electrophoretic gels. Purified ribosomal protein L22 was labeled by reductive methylation and used in 23S RNA binding assays with and without ribosomal protein L4. At the permissive temperature, protein L22 from SK1047 bound less efficiently than the control while protein L22 from SK1048 bound as efficiently as the control. At …

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Nitrogen Dioxide Reaction With Proteins: Evidence For Peptide Bond Cleavage At Lysine Residues, Darryl B. Hood May 1991

Nitrogen Dioxide Reaction With Proteins: Evidence For Peptide Bond Cleavage At Lysine Residues, Darryl B. Hood

Electronic Theses and Dissertations

Nitrogen dioxide (NO$\sb2$), an air pollutant produced by burning fossil fuels and a component of cigarette smoke, is thought to contribute to the pathogenesis of pulmonary diseases, such as emphysema. To gain information on the mechanism by which NO$\sb2$ damages the lung, in vitro exposures of $\alpha\sb1$-proteinase inhibitor ($\alpha\sb1$-PI), elastin, bovine serum albumin (BSA), human serum albumin (HSA) and synthetic poly-L-lysine were performed. A genetic deficiency of $\alpha\sb1$-PI predisposes humans to emphysema and NO$\sb2$ has been hypothesized to damage $\alpha\sb1$-PI, which would leave proteases such as human neutrophil elastase, (HNE) free to attack lung structural proteins. The ability of $\alpha\sb1$-PI …

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Mouse Mast Cell Proteases: Induction, Molecular Cloning, And Characterization, Wei Chu May 1991

Mouse Mast Cell Proteases: Induction, Molecular Cloning, And Characterization, Wei Chu

Electronic Theses and Dissertations

Tryptase, a mast cell-specific serine protease with trypsin-like specificity, has been identified in a mouse mast cell line (ABFTL-6) based on it's enzymatic activity, inhibition properties, and cross-reactivity to a human mast cell tryptase antibody. The effects of fibroblast-conditioned medium and sodium butyrate on ABFTL-6 mast cell differentiation and tryptase expression have been examined. ABFTL-6 mouse mast cells undergo phenotypic changes upon culturing in media supplemented with fibroblast-conditioned media at 50% or 1 mM sodium butyrate. The induced cells increased in size, had larger and more metachromatic cytoplasmic granules, and increased their total cellular protein about four-fold. Tryptase activity increased …

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Metabolism Of Arachidonate-Containing Phospholipid Molecular Species In The Murine Macrophage-Like Cell Line, P388d1, Crystal R. Waites May 1991

Metabolism Of Arachidonate-Containing Phospholipid Molecular Species In The Murine Macrophage-Like Cell Line, P388d1, Crystal R. Waites

Electronic Theses and Dissertations

Glycerophospholipids of mammalian cells exist as chemically diverse structures with various fatty acids at the sn-1 and sn-2 positions. Arachidonic acid, a polyunsaturated fatty acid, which may be converted to biologically active eicosanoids such as prostaglandins, thromboxanes, and leukotrienes, is found predominantly in the sn-2 position of glycerophospholipids. The purpose of this study was to examine, at the level of the individual molecular species, the incorporation of arachidonate into phospholipids and its release from phospholipids during stimulation. In this way, the specificity of the enzymes controlling arachidonate metabolism could be examined in order to clarify the processes that control the …

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A Temperature-Sensitive Mutant Of Escherichia Coli Affected In The Alpha Subunit Of Rna Polymerase, Majid Mehrpouyan Dec 1990

A Temperature-Sensitive Mutant Of Escherichia Coli Affected In The Alpha Subunit Of Rna Polymerase, Majid Mehrpouyan

Electronic Theses and Dissertations

A temperature-sensitive mutant of Escherichia coli affected in the alpha subunit of RNA polymerase has been investigated. Gene mapping and complementation experiments placed the mutation to temperature-sensitivity within the alpha operon at 72 min on the bacterial chromosome. The rate of RNA synthesis in vivo and the accumulation of ribosomal RNA were significantly reduced in the mutant at 44$\sp\circ$C. The thermostability at 44$\sp\circ$C of the purified holoenzyme from mutant cells was about 20% of that of the normal enzyme. Assays with T7 DNA as a template showed that the fraction of active enzyme competent for transcription was reduced as a …

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Electrophysiology, Cell Calcium, And Mechanisms Of Hepatocyte Volume Regulation, Walid E. Khalbuss Aug 1990

Electrophysiology, Cell Calcium, And Mechanisms Of Hepatocyte Volume Regulation, Walid E. Khalbuss

Electronic Theses and Dissertations

The electrophysiologic technique (Reuss, L., Proc. Natl. Acad. Sci. USA 82:6014, 1985) was modified to measure changes in steady-state hepatocyte volume during osmotic stress. Hepatocytes in mouse liver slices were loaded with tetramethylammonium ion (TMA$\sp{+}$) during transient exposure of cells to nystatin. Intracellular TMA$\sp{+}$ activity (a$\sp{\rm i}\sb{\rm TMA}$) was measured with TMA$\sp{+}$-sensitive, double-barreled microelectrodes. Loading hepatocytes with TMA$\sp{+}$ did not change their membrane potential (V$\sb{\rm m}$), and under steady-state conditions a$\sp{\rm i}\sb{\rm TMA}$ remained constant over 4 min in single impalements. Hyperosmotic solutions (50, 100, & 150 mM sucrose added to media) and hyposmotic solutions (sucrose in media reduced by …

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Purification And Characterization Of Enoyl-Acp Reductase From Euglena Gracilis, Margie M. Tucker May 1990

Purification And Characterization Of Enoyl-Acp Reductase From Euglena Gracilis, Margie M. Tucker

Electronic Theses and Dissertations

Enoyl-(acyl-carrier-protein) reductase was purified from the phytoflagellate Euglena gracilis. Its purification employed DEAE-Sephacel chromatography, Matrex Orange chromatography, and affinity chromatography using acyl carrier protein (ACP) covalently bound to Sepharose as the affinity ligand. Matrex Orange chromatography resolved two different enoyl-ACP reductases having different characteristics. Euglena gracilis appears to resemble higher plants in the possession of two isoforms of this enzyme. Antibodies specific for the cofactor binding site of NADP (H)-requiring dehydrogenases were obtained. They were isolated from a polyclonal population of antibodies directed against yeast glucose-6-phosphate dehydrogenase by affinity chromatography using chicken liver malic enzyme as the affinity ligand. The …

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Dopamine Agonists Modify The Development Of Brain D1 And D2 Receptor Responsiveness, Anwar A. Hamdi May 1990

Dopamine Agonists Modify The Development Of Brain D1 And D2 Receptor Responsiveness, Anwar A. Hamdi

Electronic Theses and Dissertations

Dopamine (DA) agonist-induced behavioral supersensitivity in the adult rat has served as the standard model for certain of the motor and behavioral side effects associated with long-term exposure to DA agonists in humans. The mechanisms relating receptor events with behavior mediation, however, remain unclear. The striatum of rats progresses through a prolonged and varied postnatal developmental period. In order to examine the relative contribution of D1 and D2 receptor-mediated mechanisms to behavioral changes which follow chronic dopamine agonist exposure, developing rats were treated daily from birth with a D1 agonist, SKF 38393 hydrochloride (3.0 mg/kg $\times$ 32d, i.p.), or a …

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Dopamine Agonists Modify The Development Of Brain D1 And D2 Receptor Responsiveness, Anwar A. Hamdi May 1990

Dopamine Agonists Modify The Development Of Brain D1 And D2 Receptor Responsiveness, Anwar A. Hamdi

Electronic Theses and Dissertations

Dopamine (DA) agonist-induced behavioral supersensitivity in the adult rat has served as the standard model for certain of the motor and behavioral side effects associated with long-term exposure to DA agonists in humans. The mechanisms relating receptor events with behavior mediation, however, remain unclear. The striatum of rats progresses through a prolonged and varied postnatal developmental period. In order to examine the relative contribution of D1 and D2 receptor-mediated mechanisms to behavioral changes which follow chronic dopamine agonist exposure, developing rats were treated daily from birth with a D1 agonist, SKF 38393 hydrochloride (3.0 mg/kg $\times$ 32d, i.p.), or a …

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Spatial Control Of Crop Inputs Via Laptop And Typical Field Travel, Joseph Alan Schumacher Jan 1990

Spatial Control Of Crop Inputs Via Laptop And Typical Field Travel, Joseph Alan Schumacher

Electronic Theses and Dissertations

Field Grid Sense (FGS) is a system developed for use with a laptop computer to control crop production inputs. FGS can be used for spatially controlling and recording field inputs according to regional requirements within the field. Location is identified via the travel lanes formed during field operations. Grid areas within lanes are formed by measuring from the beginning of each lane to the start of each grid within the lane. Distance measurements are reset at the beginning of each lane in order to eliminate accumulated distance error in the field. A fifth wheel, which runs in the smooth path …

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Energy-Dependent, High-Affinity Transport Of Nickel By Thermophilic Acetogenic Bacteria, Hsiuchin Yang May 1989

Energy-Dependent, High-Affinity Transport Of Nickel By Thermophilic Acetogenic Bacteria, Hsiuchin Yang

Electronic Theses and Dissertations

Nickel plays an essential role in acetogenesis at the level of acetyl-CoA synthetase, and the mechanism of nickel transport is therefore central to the metabolic capacities of acetogens. The mechanism of nickel transport by the thermophilic acetogenic bacteria Clostridium thermoaceticum ATCC 39073 and Acetogenium kivui ATCC 33488 was investigated using 63NiCl2 and an anaerobic microfiltration transport assay. Nickel transport by C. thermoaceticum was optimal at pH 7-7.5 and 65°C; nickel transport by A. kivui was optimal at pH 6.4 and 65°C. Cells during the early stages of growth displayed the highest propensity for nickel transport. Nickel transport was …

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Variants And Polymorphisms Of Three Repetitive Dna Families In The Human Genome, Robert M. Roudabush May 1989

Variants And Polymorphisms Of Three Repetitive Dna Families In The Human Genome, Robert M. Roudabush

Electronic Theses and Dissertations

A novel 0.6 kb LINE family in human DNA, designated L2Hs, has been described (Musich and Dykes 1986). Studies employing clone N6.4, containing three 0.6 kb segments of this family, indicate that these sequences are interspersed and moderately repetitive. Two additional variant sequences of the L2Hs family, N6.1 and N6.3, have been identified. Restriction mapping of each cloned segment indicates similarities among N6.4, N6.3 and N6.1. When the cloned DNAs were cleaved with restriction enzymes and subjected to cross-hybridization, each cloned insert produced a pattern indicating that the sequences contained in N6.1 and N6.3 are represented in at least one …

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Attenuation Of Antagonist-Induced Impairment Of Dopamine Receptors By L-Prolyl - L-Leucyl-Glycinamide, Mohamad I. Saleh Apr 1988

Attenuation Of Antagonist-Induced Impairment Of Dopamine Receptors By L-Prolyl - L-Leucyl-Glycinamide, Mohamad I. Saleh

Electronic Theses and Dissertations

It has been shown by others that the prenatal treatment of rats with haloperidol, a dopamine D2 receptor antagonist, leads to a permanent reduction in the number of striatal dopamine D2 receptors in adulthood. Conversely, postnatal treatment of lactating dams with haloperidol from birth for 21 days, leads to an increase in the number of striatal dopamine D2 receptors in the litters, when assessed as adults. The present study was undertaken in order to determine whether chronic, long-term postnatal challenge of rat pups per se, with specific dopamine D1 and D2 receptor antagonists, would modify the ontogeny of the respective …

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Lactational Evaluation Of Recombinant Bovine Somatotropin With Corn And Barley Diets, Wade Arthur Eisenbeisz Jan 1988

Lactational Evaluation Of Recombinant Bovine Somatotropin With Corn And Barley Diets, Wade Arthur Eisenbeisz

Electronic Theses and Dissertations

Forty-eight Holstein cows were randomly assigned wk 3 postpartum to a corn or barley diet from wk 4 through 44 postpartum. Cows within diets at wk 14 were randomly assigned to receive 0 (control), 10.3, 20.6, and 30.9 mg/hd/d of recombinant bovine somatotropin injected wk 15 through 44 postpartum. Forage dry matter was 80% corn silage and 20% alfalfa hay. Forage to concentrate ratio in total mixed diets varied from 50:50 to 70:30 with milk production. For the entire lactation, milk production of (29.7 and 29.1 kg/d) and 4% FCM (27.3 and ·25.9 kg/d) was lower for cows fed barley …

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Characteristics Of Milk And Butter From Cows Fed Sunflower Seeds, Robert Paul Middaugh Jan 1988

Characteristics Of Milk And Butter From Cows Fed Sunflower Seeds, Robert Paul Middaugh

Electronic Theses and Dissertations

Composition of milk and butter was evaluated from cows fed either control, or experimental diets containing added added fat of partially unsaturated fatty acid composition. The control diet concentrate mix consisted mainly of corn and soybean meal. The two experimental diets substituted either 20% high oleic acid sunflower seeds () 79% of fatty acids as oleic acid) or 20% regular sunflower seeds () 67% of fatty acids as linoleic acid) for part of the corn and soybean meal in the concentrate -mix. Milk protein concentration was similar for the control (3.3%) and high oleic sunflower seeds (3.3%), but increased in …

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