The in vivo unidirectional conversion of nitro-D-arginine to nitro-L-arginine.

We recently reported that nitric oxide synthase in the brain can be inhibited not only by nitro-L-arginine (L-NA) but also by its D-enantiomer nitro-D-arginine (D-NA). In the present study, we found that D-NA, when tested in vitro, was 400 times less potent than L-NA. However, when D-NA was injected in vivo, its L-enantiomer, L-NA, was found to rapidly appear in plasma samples (approximately 1 min), rose to a maximum concentration at 30 min (approximately 40% conversion), and remained at this plateau for about 5 h.

Equine peripheral blood mononuclear cells proliferate in response to tetanus toxoid antigen.

It has been reported that equine peripheral blood mononuclear cells (PBMNs) do not proliferate in response to tetanus toxoid (TT) (Frayne and Stokes 1995, Research in Veterinary Science 59, 79-81). Here we demonstrate that lymphocyte proliferation responses to TT, which are characteristic of a recall antigen, may be achieved under certain culture conditions. Given that TT vaccination is routinely applied to many horses, TT is a suitable antigen for the investigation of cellular immune responses by peripheral blood mononuclear cells in the horse.

Inhibition of antigen-induced cutaneous responses of ponies with insect hypersensitivity by the histamine-1 receptor antagonist chlorpheniramine.

A whole-body extract of Culicoides impunctatus induced a biphasic increase in oedema formation in ponies with insect hypersensitivity, with maxima after one and eight hours. The Culicoides antigen did not induce similar responses in ponies with no previous history of the disease. In insect-hypersensitive ponies the local administration of chlorpheniramine (12 micrograms) completely inhibited oedema formation in response to histamine (0.

Differential expression of two isopentenyl pyrophosphate isomerases and enhanced carotenoid accumulation in a unicellular chlorophyte.

The enzyme isopentenyl pyrophosphate (IPP) isomerase catalyzes the reversible isomerization of IPP to produce dimethylallyl pyrophosphate, the initial substrate leading to the biosynthesis of carotenoids and many other long-chain isoprenoids. Expression of IPP isomerase, and of two enzymes specific to the carotenoid pathway (lycopene beta-cyclase and beta-carotene-C-4-oxygenase), was followed in the green unicellular alga Haematococcus pluvialis after exposure to high illumination. This alga uniquely accumulates carotenoids in the cytoplasm and in late developmental stages turns deep-red in color because of accumulation of ketocarotenoids in the cytosol.

Histamine-induced adherence and migration of equine eosinophils.

Objectives: To examine effects of histamine on equine eosinophil adherence in vitro and to determine the histamine receptor subtype(s) and cell surface adhesion molecules that mediate this response. In addition, to determine the receptor subtypes involved in histamine-induced eosinophil migration.

Animals: 8 healthy ponies.

Inhaled leukotrienes cause bronchoconstriction and neutrophil accumulation in horses.

Leukotrienes have been shown to mimic many of the pathophysiological processes in allergic airway disease. In this study the bronchoconstrictor effect of inhaled LTD4, and radiolabelled neutrophil accumulation in response to inhalation of LTB4, have been examined in the horse. In separate studies, solutions of LTD4 and LTB4 were administered to the airways of normal animals by nebulisation.

Effect of the 5-lipoxygenase inhibitor, fenleuton, on antigen-induced neutrophil accumulation and lung function changes in horses with chronic obstructive pulmonary disease.

The leukotrienes (LT) LTD4 and LTB4 have been shown to cause bronchoconstriction and neutrophil accumulation, respectively, in horse lungs. Such changes are characteristic of the equine allergic respiratory disease, chronic obstructive pulmonary disease (COPD). To further investigate the role of these putative mediators in the pathogenesis of equine COPD the effect of a 5-lipoxygenase inhibitor, fenleuton, on antigen-induced changes in horses with this condition has been examined.

Pharmacokinetics and pharmacodynamics of fenleuton, a 5-lipoxygenase inhibitor, in ponies.

Leukotrienes, products of the 5-lipoxygenase pathway of arachidonic acid metabolism, possess properties consistent with their involvement in a range of inflammatory diseases. In this study the pharmacokinetics and pharmacodynamics of the selective 5-lipoxygenase inhibitor, fenleuton, have been examined in the horse. Orally administered fenleuton (four 5 mg kg(-1) doses, given once daily) was absorbed from the gastrointestinal tract, and penetrated readily into tissue cage exudate, the ratio of the plasma:exudate AUC0-48h being 0.

The long-term consequences of thrombotic microangiopathy (thrombotic thrombocytopenic purpura and hemolytic uremic syndrome) in pregnancy.

Objective: To characterize perinatal outcomes and long-term maternal complications from thrombotic microangiopathy manifested during pregnancy, and to review the clinical course and long-term follow-up of pregnant women with this condition at our institution over the past 25 years.

Methods: We identified prospectively pregnant women who met clinical and laboratory criteria for thrombotic thrombocytopenic purpura or hemolytic uremic syndrome. Their clinical and laboratory findings, response to treatment, perinatal outcomes, and long-term sequelae were then analyzed.

Differential changes in inhibin A, activin A, and total alpha-subunit levels in granulosa and thecal layers of developing preovulatory follicles in the chicken.

Accumulating evidence implicates inhibins and activins as endocrine and local regulators of follicular development in mammals, and it was recently confirmed that inhibin/activin alpha and betaA genes are also expressed in the avian ovary. To investigate the potential involvement of these proteins in the chicken ovary, thecal and granulosa layers of the four largest follicles (F1-F4) and the most recent postovulatory follicle were collected from hens (10/group) killed 4, 12, and 20 h before the expected time of F1 ovulation. Inhibin A and activin A concentrations of tissue extracts (expressed per mg DNA) were measured using validated two-site enzyme-linked immunosorbent assays; total immunoreactive inhibin alpha-subunit (ir-alpha) was also measured by heterologous RIA (Monash assay).

Differential superoxide anion generation by equine eosinophils and neutrophils.

Equine eosinophils and neutrophils are believed to play an important part in the protection of horses against parasitic and bacterial invasion. Eosinophils may also play a key role in the pathogenesis of equine inflammatory conditions such as the allergic skin disease, insect hypersensitivity. The factors which stimulate the respiratory burst of equine eosinophils and neutrophils are poorly understood.

Influence of antigen challenge on platelet responsiveness in horses with chronic obstructive pulmonary disease.

A role for platelets in allergic airways disease has been postulated and changes in the responsiveness of circulating platelets have been demonstrated following antigen challenge of asthmatic human subjects. In this study agonist-induced aggregation of equine platelets in vitro has been compared before and after exposure of horses to a controlled hay and stray challenge. Prior to challenge the response of platelets, from horses with chronic obstructive pulmonary disease (COPD) and normal animals, to adenosine diphosphate (ADP) and platelet activating factor (PAF) did not differ.

Cesarean delivery: a randomized trial of epidural versus patient-controlled meperidine analgesia during labor.

Background: Reports indicate that the administration of epidural analgesia for pain relief during labor interferes with labor and increases cesarean deliveries. However, only a few controlled trials have assessed the effect of epidural analgesia on the incidence of cesarean delivery. The authors' primary purpose in this randomized study was to evaluate the effects of epidural analgesia on the rate of cesarean deliveries by providing a suitable alternative: patient-controlled intravenous analgesia.

Imaging of puerperal septic thrombophlebitis: prospective comparison of MR imaging, CT, and sonography.

Objective: Our objective was to compare prospectively the abilities of MR imaging, CT, and sonography to reveal puerperal septic thrombophlebitis in the pelvis.

Subjects And Methods: Seventy-six women with puerperal fever for 5 days refractory to antimicrobial therapy underwent MR imaging, CT, and sonography. We obtained unenhanced axial CT images followed by enhanced images after the administration of an oral contrast agent for which we followed a specific protocol.

Pharmacology of the 5-lipoxygenase inhibitors BAY Y 1015 and BAY X 1005 in the horse.

Calcium ionophore A23187 induced time and concentration dependent production of immunoreactive leukotriene (LT) B4 by equine heparinized whole blood in vitro. Time dependent production of immunoreactive LTB4 by equine neutrophils and immunoreactive LTC4 by equine eosinophils in vitro was also demonstrated. The 5-lipoxygenase activating protein (FLAP) inhibitors, BAY X 1005 and BAY Y 1015, produced concentration dependent inhibition of ionophore-induced LTB4 synthesis by equine whole blood (mean +/- SEM IC50s n = 5; 6.

Effect of antigen challenge on the activation of peripheral blood neutrophils from horses with chronic obstructive pulmonary disease.

The effect of antigen challenge on the state of activation of peripheral blood neutrophils from horses with chronic obstructive pulmonary disease (COPD) has been determined by measuring neutrophil superoxide anion formation. Prior to a seven-hour antigen challenge superoxide anion production by neutrophils from asymptomatic horses with COPD and normal horses in response to platelet activating factor (PAF) (with and without cytochalasin B), serum treated zymosan (STZ) and phorbol myristate acetate (PMA) was similar. Agonist-induced superoxide production by neutrophils from symptomatic COPD and normal horses remained unchanged five and 24 hours after antigen challenge.

Agonist-induced adherence of equine eosinophils to fibronectin.

Eosinophils are believed to play an important part in the pathogenesis of equine diseases such as helminth infestation and the allergic skin disease, sweet itch. It has been shown that adherence of human eosinophils to the connective tissue matrix protein fibronectin enhances cell activation and survival time. If adherence causes similar changes in the properties of equine eosinophils, cell-induced tissue damage at a site of parasitic infestation or allergic response would be exacerbated.

Comparative pharmacokinetics and pharmacodynamics of remifentanil, its principle metabolite (GR90291) and alfentanil in dogs.

Remifentanil is an esterase-metabolized opioid developed for use in anesthesia. The principal metabolite of remifentanil, GR90291, is considered to be less potent. This study determined the relative potency of GR90291 and alfentanil, compared with remifentanil, in anesthetized dogs.

Cerebral blood flow and cranial magnetic resonance imaging in eclampsia and severe preeclampsia.

Objective: To measure cerebral blood flow in women with eclampsia and severe preeclampsia using phase-contrast magnetic resonance imaging (MRI).

Methods: Women with eclampsia and severe preeclampsia were studied and compared with normotensive cohorts. Magnetic resonance imaging studies were performed initially in hypertensive women after seizure treatment or prophylaxis was given.

LhcaR1 of the red alga Porphyridium cruentum encodes a polypeptide of the LHCI complex with seven potential chlorophyll a-binding residues that are conserved in most LHCs.

The accessory light-harvesting polypeptides associated with photosystem I (LHCI) in Porphyridium cruentum bind chlorophyll a, zeaxanthin and beta-carotene. A cDNA library of P. cruentum was screened with an antiserum specific to the LHCI polypeptides, and an 0.

Cloning and functional analysis of the beta-carotene hydroxylase of Arabidopsis thaliana.

An Arabidopsis thaliana cDNA encoding the enzyme beta-carotene hydroxylase was identified by functional complementation in Escherichia coli. The product of this cDNA adds hydroxyl groups to both beta rings of the symmetrical beta-carotene (beta,beta-carotene) to form zeaxanthin (beta,beta-carotene-3,3'-diol) and converts the monocyclic beta-zeacarotene (7',8'-dihydro-beta,psi-carotene) to hydroxy-beta-zeacarotene (7',8'-dihydro-beta,psi-carotene-3-ol). The epsilon rings of delta-carotene (epsilon,psi-carotene) and alpha-zeacarotene (7',8'-dihydro-epsilon,psi-carotene) are poor substrates for the enzyme.

Effects of platelet activating factor on the distribution of radiolabelled leucocytes and platelets in normal horses and asymptomatic horses with chronic obstructive pulmonary disease.

Antigen challenge is known to cause the recruitment of neutrophils to the lungs of horses with chronic obstructive pulmonary disease (COPD). To evaluate a possible role of platelet activating factor (PAF) in this process, the effects of PAF on the distribution of radiolabelled neutrophils were compared in normal horses and asymptomatic horses with COPD. Changes in lung function, heart rate and the distribution of platelets and eosinophils were also measured.

Functional analysis of the beta and epsilon lycopene cyclase enzymes of Arabidopsis reveals a mechanism for control of cyclic carotenoid formation.

Carotenoids with cyclic end groups are essential components of the photosynthetic membranes in all plants, algae, and cyanobacteria. These lipid-soluble compounds protect against photooxidation, harvest light for photosynthesis, and dissipate excess light energy absorbed by the antenna pigments. The cyclization of lycopene (psi, psi-carotene) is a key branch point in the pathway of carotenoid biosynthesis.

Pharmacologic management of postdural puncture headache.

Objective: To discuss the pathogenesis, incidence, and clinical presentation of postdural puncture headaches (PDPHs) and to provide a comprehensive evaluation on the pharmacologic management of PDPH.

Data Source: A MEDLINE search was used to identify pertinent literature published in English including review articles, case reports, letters, and abstracts. Information was also extracted from textbooks for background purposes.