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Biomedical subjects

L Viera

Publications and source records attributed to L Viera.

12 recordsLinked to original sources
PubMed2004

Short communication: influence of Staphylococcus aureus intramammary infection on serum copper, zinc, and iron concentrations.

The goal of the present study was to characterize changes in serum trace mineral concentrations in cattle with experimentally induced Staphylococcus aureus mastitis. Nine primiparous Holstein-Friesian cattle were challenged with approximately 150 cfu of Staph. aureus ATCC29740 by intramammary infusion on d 6, 7, and 8 of lactation. Serum Cu, Zn, and Fe concentrations were determined immediately before and at 24, 48, and 72 h after the final intramammary infusion of Staph. aureus. Infection status (cfu/mL of Staph. aureus), milk somatic cell count, and mastitis score were also determined at these times. Infection resulted in a decrease in mean serum Cu, Zn, and Fe concentrations to 89, 83, and 81% of preinfection concentrations at 24 h postchallenge. One-way analysis of variance for repeated measures demonstrated a significant change in serum zinc concentration. The reductions in trace mineral concentrations were of less magnitude than observed following experimental E. coli mastitis.

Animals↗
PubMed2000

Nitric oxide and peroxynitrite in the perinatal period.

Many of the actions of nitric oxide are not due to nitric oxide itself, but rather by the secondary formation of oxidants like peroxynitrite. Peroxynitrite leaves a footprint in the nitration of tyrosine, which helps track the formation of reactive nitric oxide-derived species in diseases and even normal development.

Animals↗
PubMed2000

Protein nitration, metabolites of reactive nitrogen species, and inflammation in lung allografts.

This study investigated nitration and chlorination of epithelial lining fluid (ELF) proteins in patients (n = 29) who had undergone lung allotransplantation. We assayed lung lavage nitrotyrosine (NT) and chlorotyrosine (CT) by HPLC. We measured NT, nitrate (NO(3)(-)), and nitrate (NO(2)(-)) in bronchoalveolar lavage fluid (BALF) and total nitrite (NO(2)(-) + NO(3)(-)) in serum of another group of lung transplant patients (n = 82). In the first group (n = 29), percent nitration of tyrosines (Tyr) (NT/total Tyr x 100) in BALF proteins was: patients, 0.01 (0.00-0.12)%; median (25th-75th% confidence interval), and control subjects 0.01 (0.00-0.02)%. CT (CT/ total Tyr x 100) occurred only in the patients' BALF: 0.01 (0. 00- 0.02)%. In the second group (n = 82), nitrotyrosine (NT) was detected by ELISA in the BALF of patients: 9 (0-41) pmol/mg pro and control subjects: 28 (26-33). Total nitrite (NO(2)(-) + NO(3)(-)) in BALF of the patients: 3.3 (1.9-5.1) microM significantly exceeded that in control subjects: 1.3 (0.8-1.3) microM; p = 0.0133. Serum nitrite also was significantly higher in patients: 37 (26-55) microM than control subjects: 19 (17-20) microM; p = 0.0037. Airway inflammation in transbronchial biopsies (B score) correlated with NT in BALF (p = 0.0369). Lung transplants have increased airway concentrations of reactive nitrogen species (RNS) metabolites. NT, a marker of peroxynitrite (ONOO(-)), is related to the degree of airway inflammation in lung transplants.

Adult↗
PubMed1999

Immunohistochemical methods to detect nitrotyrosine.

The immunohistochemical detection of nitrotyrosine is a robust method for detecting peroxynitrite and other reactive nitrogen species. Success depends on optimizing conditions for the particular tissue and experimental design under investigation and the use of positive and negative controls to verify specificity. The two controls of dithionite reduction and blocking with nitrotyrosine are a powerful combination to demonstrate specificity. The pathological significance of tyrosine nitration in proteins can also be approached. Generally, nitrated proteins can be isolated from diseased tissues by immunoprecipitation and Western blotting. The sites of nitration on specific proteins can be determined by mass spectrometry, which has revealed surprising specificity in which tyrosines and/or proteins are nitrated in vivo. This provides important evidence concerning the functional consequences of peroxynitrite formation in vivo.

Animals↗
PubMed1999

Peroxynitrite irreversibly decreases diastolic and systolic function in cardiac muscle.

Much of the damaging action of nitric oxide in heart may be due to its diffusion-limited reaction with superoxide to form peroxynitrite. Direct infusion of peroxynitrite into isolated perfused hearts fails to model the effects of in situ formation because the bulk of peroxynitrite decomposes before reaching the myocytes. To examine the direct effects of peroxynitrite on the contractile apparatus of the heart, we exposed intact and skinned rat papillary muscles to a steady state concentration of 4-microM peroxynitrite for 5 min, followed by a 30-min recovery period to monitor irreversible effects. In intact muscles developed force fell immediately to 26% of initial force, recovering to 43% by 30 min. Resting tension increased by 600% immediately, and was still elevated 500% by 30 min. Nitrotyrosine immunochemistry showed that peroxynitrite can induce tyrosine nitration at low concentrations and is capable of penetrating 200-380 microm into the papillary muscle after a 5-min infusion. Decomposed peroxynitrite had no effect on either intact or skinned muscle developed force or resting tension. Our results show that peroxynitrite directly damages both developed force and resting tension of isolated heart muscle, which can be extrapolated to systolic and diastolic injury in intact hearts.

Animals↗
PubMed1992

Different functional pools of acetylcholinesterase induce changes in rat locus coeruleus noradrenaline metabolism.

The effects of acetylcholinesterase (AChE) inhibition in the locus coeruleus (LC) were studied in rats utilizing fasciculin (FAS) and BW248c51 (BW). Both inhibitors were stereotaxically injected into the right LC and the animals were sacrificed 24 h later. Similar groups received atropine (30 mg/kg i.p.) every 5 h during 24 h. Another group of FAS-treated rats received naloxone twice (5 mg/kg i.p.) in 24 h. Other groups of FAS-treated rats were sacrificed 3 and 7 days after injection. An inhibition of 70% of LC AChE activity was observed 24 h after FAS or BW injection. Either FAS or BW induced a significant increase in NA levels in the injected LC compared to control values. Atropine treatment failed to block the FAS effect but it was able to counteract the BW-induced NA increase. NA levels were still increased 3 days after FAS treatment and returned to control values at day 7.

Acetylcholinesterase↗
PubMed1989

Effects of local inhibition of locus coeruleus acetylcholinesterase by fasciculin in rats.

The inhibition of locus coeruleus (LC) acetylcholinesterase (AChE) by Fasciculin II (FAS), a novel anticholinesterase peptide from the green mamba (Dendroaspis angusticeps) venom, was studied in rats. FAS was stereotaxically injected (0.5 microliters of a 1 mg/ml solution) in the right LC. The left LC was taken as control. A group of rats received only saline injected with the same procedure. An inhibition of 80% of LC AChE activity was observed 24 h later. Monoamine and metabolite levels were assessed by high-performance liquid chromatography (HPLC) with electrochemical detection. A significant increase of noradrenaline (NA) levels was found in the injected side when compared with controls 24 h after injection. Neither dopamine, serotonin nor their metabolites or the NA metabolite 4-methoxyhydroxyphenylglycol showed any change after FAS injection. Atropine (30 mg/kg, i.p.) did not prevent the NA increase.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1988

Intrastriatal dendrotoxin injection: behavioral and neurochemical effects.

Unilateral striatal injection of dendrotoxin (DTX), a polypeptide isolated from the venom of the snake Dendroaspis angusticeps, in rats provoked a complex behavioral syndrome characterized by spontaneous circling towards the contralateral side, stereotypic like chewing movements and gnawing, abnormal postures and convulsions. All these symptoms achieved their maximum on the first day, disappearing during the first week after injection. Neurochemical analyses of striatal monoamines and monoamine metabolites showed a significant increase of dopamine and serotonin metabolites 20 hr after DTX injection. A group of animals sacrificed 15 days after toxin administration showed normal levels of monoamines and their metabolites, except for homovanillic acid levels which were still significantly increased. These data indicate that monoamines are involved in the behavioral syndrome elicited by DTX and are possibly related to its excitatory effect upon brain structures in vivo.

Animals↗
PubMed1987

Endoscopic cholangiopancreatography in the infant: evaluation of a new prototype pediatric duodenoscope.

The usefulness of a new pediatric duodenoscope PJF in the diagnosis of neonatal cholestasis was studied in 23 infants with ages ranging from 19 to 150 days. In 22 of 23 infants the papilla was cannulated. In 13 of 14 neonates (93%) with neonatal hepatitis, the common bile duct was opacified and biliary atresia was excluded. In one of two neonates with choledochal cyst, the common bile duct was demonstrated. In six of seven neonates (86%) with biliary atresia, only the pancreatic duct was demonstrated and the diagnosis was suspected. Although absence of a common bile duct opacification does not rule out biliary atresia, ERCP with the new duodenoscope proved to be most useful in the diagnosis of normal biliary tree and served to avoid unnecessary surgery in most infants with neonatal cholestasis.

Biliary Atresia↗
PubMedDate not supplied

Somatostatin prevents acute pancreatitis after pancreatic duct sphincter hydrostatic balloon dilation in patients with idiopathic recurrent pancreatitis.

The purpose of this study was to determine whether prophylactic somatostatin infusion can prevent pancreatitis after hydrostatic balloon dilation of the pancreatic duct sphincter segment in 16 patients with idiopathic recurrent pancreatitis. This study demonstrated that prophylactic administration of somatostatin before, during, and after the procedure diminished the incidence and severity of acute pancreatitis. We recommend consideration of such prophylaxis in patients undergoing this procedure.

Acute Disease↗
PubMedDate not supplied

Survival, lung injury, and lung protein nitration in heterozygous MnSOD knockout mice in hyperoxia.

This study tested whether a strain of heterozygous Mn superoxide dismutase (SOD) knockout mice differed from wild types in response to lethal (100 or 85%) or sublethal (50 or 75%) oxygen exposures. Lung MnSOD activity was significantly (-40%) less in the heterozygous mice, and lung catalase activity was also significantly decreased. Total SOD activity, glutathione peroxidase, and glutathione reductase did not differ between heterozygous (+/-) and wild-type (+/+) mice. We exposed both heterozygous and wild-type mice to hyperoxia (50, 75, 85, or 100% oxygen) until death or for 48 hours to assess sublethal lung injury. Survival of the heterozygous and wild-type mice did not differ significantly in 100 or 85% oxygen. No mice of either genotype died in 50 or 75% oxygen (14-day exposures). Hyperoxia exposures significantly increased (by two-way ANOVA) the alveolar lavage protein concentration, percent neutrophils, and lung wet-dry/dry weight ratios. No significant differences occurred between the heterozygous and wild-type mice for any marker of injury at any oxygen level. Lavage fluid total nitrite concentrations did not differ at any oxygen level. Hyperoxia caused a similar degree of nitration of lung structural proteins detected by immunohistochemistry in both groups.

Animals↗