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Biomedical subjects

S Patton

Publications and source records attributed to S Patton.

At least 37 records · Page 2Linked to original sources
PubMed1997

L-arginine treatment alters the kinetics of nitric oxide and superoxide release and reduces ischemia/reperfusion injury in skeletal muscle.

BACKGROUND: Constitutive nitric oxide synthase (cNOS) may produce species involved in ischemia/reperfusion (I/R) injury: NO in the presence of sufficient L-arginine and superoxide at the diminished local L-arginine concentration accompanying I/R. METHODS AND RESULTS: During hindlimb I/R (2.5 hours/2 hours), in vivo NO was continuously monitored (porphyrinic sensor), and L-arginine (chromatography), superoxide (chemiluminescence), and I/R injury were measured intermittently. Normal rabbits were compared with those infused with L-arginine 4 mg x kg(-1) x min(-1) for 1 hour. In both groups, approximately 6 minutes into ischemia, a rapid increase of NO from its basal level of 50+/-17 to 115+/-7 nmol/L, P<.005 (microvessels), was observed. In animals not treated with L-arginine, NO dropped below basal to undetectable levels (<1 nmol/L) during reperfusion. In animals treated with L-arginine, the decrease of NO was slower, such that substantial amounts accumulated during reperfusion (25 nmol/L). Decreased NO during I/R was accompanied by increased superoxide, which during reperfusion reached 50 nmol/L without or 23 nmol/L with L-arginine treatment. Calcium-dependent cNOS was a major source of superoxide release (inhibited 70% by L-NMMA and 25% by L-NAME) during I/R. CONCLUSIONS: L-Arginine treatment decreased superoxide generation by cNOS while increasing NO accumulation, leading to protection from constriction (microvessel area, 17.77+/-0.95 versus 11.66+/-2.21 microm2 untreated, P<.0005) and reduction of edema after reperfusion (interfiber area, 16.56+/-2.13% versus 27.68+/-7.70% untreated, P<.005).

Animals↗
PubMed1997

Mechanical transduction of nitric oxide synthesis in the beating heart.

NO alters contractile and relaxant properties of the heart. However, it is not known whether changes in ventricular loading conditions affect cardiac NO synthesis. To understand this potential contractile-relaxant autoregulatory mechanism, production of cardiac NO in response to mechanical stimuli was measured in vivo using a porphyrinic sensor placed in the left ventricular myocardium. The beating rabbit heart exhibited cyclic changes in [NO], peaking at 2.7+/-0.1 micromol/L near the endocardium and 0.93+/-0.20 micromol/L in the midventricular myocardium (concentrations were 15+/-4% lower in the rat heart). In the present study, we demonstrate for the first time that increasing or decreasing ventricular preload in vivo is followed by parallel changes in [NO], which may represent a novel autoregulatory mechanism to adjust cardiac performance or perfusion on a beat-to-beat basis. To quantify the relationship between applied force and NO synthesis, intermittent compressive or distending forces applied to ex vivo nonbeating hearts were shown to cause bursts of NO synthesis, with peak [NO] linearly related to ventricular transmural pressure. Experiments in which denuding cardiac endothelial and endocardial cells abrogated the NO signal indicate that these cells transduce mechanical stimulation into NO production in the heart. Taken together, these studies may help explain load-dependent relaxation, cardiac memory for mechanical events of preceding beats, diseases associated with myocardial distension, autoregulation of myocardial perfusion, and protection from thrombosis in the turbulent flow environment within the beating heart.

Animals↗
PubMed1997

Prosaposin, a neurotrophic factor: presence and properties in milk.

The presence of prosaposin, the precursor of the sphingolipid activator proteins (saposins A, B, C, and D), was investigated in bovine milk. The milk proteins were resolved by SDS-PAGE, blotted onto nitrocellulose sheets, and immunostained. Each of three appropriate antibodies defined a band from milk that matched in mobility the reference prosaposin from human milk at a relative molecular mass of 66,000. Evidence of mature saposins was not found. Prosaposin was detected in milk of other species chimpanzee, rhesus, goat, and rat) and was consistently observed in samples of retail milk and from individual cows. Prosaposin was not associated with particulate matter (fat globules, casein micelles, membrane fragments, and somatic cells) in either human or bovine milk. Rather, prosaposin was located exclusively in the milk serum (whey), existing in monomeric form, as revealed by nondenaturing PAGE. A commercial whey protein concentrate (75% protein) appeared to retain milk prosaposin quantitatively. Properties that were useful in the isolation of prosaposin from milk were its binding to concanavalin A, retention by anion-exchange cellulose, and resistance to precipitation by heating. The possibility that bovine milk prosaposin nutritionally benefits the humans who consume it is enhanced by the fact that only part of its saposin C segment is required for neurotrophic activity.

Animals↗
PubMed1997

Helminths in ruffed grouse at the host's southeastern range boundary.

Carcasses of 268 ruffed grouse (Bonasa umbellus) collected in eastern Tennessee (USA) from October 1983 through February 1988 were examined between 16 January 1985 and 25 April 1988 for non-filarioid helminths. Three nematode species and one cestode species were found. The two most common parasites were the cecal worm Heterakis bonasae (81% prevalence, mean intensity +/- SD of 62 +/- 114) and the tapeworm Echinolepis carioca (27% prevalence, 30 +/- 73 mean intensity). Age and sex of host were sufficient to predict infection by both common species. Condition of host and year and month of collection also had significant effects on prevalence. Intensity of cecal worm infection varied with age and condition of host and with region and month of collection.

Age Distribution↗
PubMed1997

Sucking lice (Anoplura) of mammals of Tennessee.

Twenty-five species of sucking lice are recorded from wild and domestic mammals, including humans, from Tennessee. Collections of 10 of these species (Haematopinus eurysternus, Hoplopleura captiosa, Hoplopleura hirsuta, Hoplopleura oryzomydis, Hoplopleura trispinosa, Linognathus africanus, Linognathus setosus, Linognathus vituli, Neohaematopinus sciuropteri and Polyplax auricularis) represent newly documented state records. Host specificity was exhibited by 22 species of lice with each of these species being recovered from just one mammal species. Louse infestation prevalences are included for large samples of hosts. A host-parasite list for Tennessean sucking lice is included.

Animals↗
PubMed1997

In situ measurement of nitric oxide, superoxide and peroxynitrite during endotoxemia.

We report in vivo and ex vivo measurements of nitric oxide (electrochemical), ex vivo in situ measurements of superoxide (chemiluminescence) and peroxynitrite (chemiluminescence) and delineate the effect of endotoxemia on nitric oxide, superoxide and peroxynitrite release in aorta of rats. Nitric oxide release was measured in the aorta wall. An increase of nitric oxide concentration was observed immediately after administration of lipopolysaccharide (Escherichia coli serotype 0127: B8, 20 mg/kg), reaching a plateau ((50 nmol/L) after 180 +/- 50 seconds; the plateau was followed by decreasing nitric oxide concentration and its subsequent gradual small increase after 45 minutes. Superoxide and peroxynitrite production increased dramatically during endotoxemia. Superoxide concentration increased from 10 +/- 2 nmol/L to 28 +/- 3 nmol/L at one hour, and reached a 50 nmol/L plateau at 4 hours. The pattern of peroxynitrite release paralleled the pattern of superoxide release during the time course of endotoxemia. Diametrical alteration of nitric oxide and superoxide concentration with subsequent production of peroxynitrite may be a major cause of endothelial cell injury during endotoxemia.

Animals↗
PubMed1996

Cloning and characterization of the gene encoding 1-cyclohexenylcarbonyl coenzyme A reductase from Streptomyces collinus.

We report the cloning of the gene encoding the 1-cyclohexenylcarbonyl coenzyme A reductase (ChcA) of Streptomyces collinus, an enzyme putatively involved in the final reduction step in the formation of the cyclohexyl moiety of ansatrienin from shikimic acid. The cloned gene, with a proposed designation of chcA, encodes an 843-bp open reading frame which predicts a primary translation product of 280 amino acids and a calculated molecular mass of 29.7 kDa. Highly significant sequence similiarity extending along almost the entire length of the protein was observed with members of the short-chain alcohol dehydrogenase superfamily. The S. collinus chcA gene was overexpressed in Escherichia coli by using a bacteriophage T7 transient expression system, and a protein with a specific ChcA activity was detected. The E. coli-produced ChcA protein was purified and shown to have similar steady-state kinetics and electrophoretic mobility on sodium dodecyl sulfate-polyacrylamide gels as the enoyl-coenzyme A reductase protein prepared from S. collinus. The enzyme demonstrated the ability to catalyze, in vitro, three of the reductive steps involved in the formation of cyclohexanecarboxylic acid. An S. collinus chcA mutant, constructed by deletion of a genomic region comprising the 5' end of chcA, lost the ChcA activity and the ability to synthesize either cyclohexanecarboxylic acid or ansatrienin. These results suggest that chcA encodes the ChcA that is involved in catalyzing multiple reductive steps in the pathway that provides the cyclohexanecarboxylic acid from shikimic acid.

Amino Acid Sequence↗
PubMed1995

The epithelial mucin, MUC1, of milk, mammary gland and other tissues.

MUC1 is a mucin-type glycoprotein that is integrally disposed in the apical plasma membrane of the lactating epithelial cell and protrudes from the cell surface into the alveolar lumen where milk is stored. Envelopment of milk fat globules by this membrane accomplishes their secretion and conveys MUC1 into milk. The human form of this mucin has been detected in many other organs, tissues and body fluids. It projects from the cell surface as long filaments. In the human and a number of other species, MUC1 is polymorphic due to variable numbers of a tandemly repeated segment 20 amino acids in length. The individual codominantly expresses two alleles for the mucin so that differences in its size among individuals and between the two forms of an individual are observed. The tandem repeats are rich in serines and threonines which serve as O-glycosylation sites. Carbohydrate content of MUC1, as isolated from milk of human, bovine and guinea pig, is approximately 50%. The oligosaccharides carry substantial sialic acid at their termini and this accounts for two putative functions of this mucin, i.e., to keep ducts and lumens open by creating a strong negative charge on the surface of epithelial cells which would repel opposite sides of a vessel, and to bind certain pathogenic microorganisms. MUC1 is protease resistant (trypsin, chymotrypsin and pepsin) and large fragments of it can be found in the feces of some but not all breast-fed infants. MUC1 has a highly varied structure because of its polymorphism, qualitative and quantitative variations in its glycosylation between tissues, individuals and species, and differences due to divergence in the nucleotide sequences among species. Sequencing of the MUC1 gene for various species is showing promise of revealing unique evolutionary relationships and has already indicated conserved aspects of the molecule that may be functionally important. Among these are positions of serine, threonine and proline in the tandem repeats and a high degree of homology in the transmembrane and cytoplasmic segments of the molecule.

Amino Acid Sequence↗
PubMed1995

Direct measurement of nitric oxide in human beings.

Nitric oxide is a short-lived radical involved in various biological processes. We have used an electrochemical microsensor to detect nitric oxide signals in blood vessels of healthy volunteers. The sensor was inserted into a hand vein, and the vessel was stimulated with acetylcholine or bradykinin. Dose-dependent signals were detected and were attenuated by an inhibitor of nitric oxide synthase. The results provide further evidence that endothelium-derived relaxing factor is nitric oxide and demonstrate a method for monitoring the L-arginine/nitric-oxide pathway in human beings.

Acetylcholine↗
PubMed1995

Comparison of the efficacies of three heartworm preventives against experimentally induced infections with Ancylostoma caninum and Toxocara canis in pups.

Forty 11- to 12-week-old helminth-naive Beagles were categorized by sex and weight and randomly assigned to 4 treatment groups (group 1, ivermectin/pyrantel pamoate; group 2, milbemycin oxime; group 3, untreated control; group 4, diethylcarbamazine/oxibendazole). Each pup was inoculated PO with approximately 100 infective Ancylostoma caninum larvae and 100 larvated Toxocara canis eggs on day 0, and repeatedly at 7-day intervals thereafter until day 56. Administration of anthelmintics also began on day 0, and subsequent treatments were administered according to label recommendations at 30-day intervals (groups 1 and 2) or daily (group 4) for a period of 90 consecutive days. Body weight and A caninum and T canis fecal egg counts were measured at weekly intervals, and clinical observations of health status were conducted twice daily. Pups were euthanatized on day 90, and total gastrointestinal worm burdens were determined. Compared with mean A caninum egg counts of group-3 control pups, egg counts in group-1 pups were significantly (P < or = 0.0001) lower on every sampling days 35, 42, 49, 63, 70, 77, and 84, and were consistently the highest of all treated groups, and egg counts of group-4 pups were significantly (P < or = 0.0001) lower on every sampling date from day 14 to day 90, and were consistently the lowest of all treated groups. Compared with mean A caninum egg counts of group-3 pups, egg counts in group-1 and group-2 pups were lower by 97.8 and 90.8%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗