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Biomedical subjects

L Araujo

Publications and source records attributed to L Araujo.

At least 19 recordsLinked to original sources
PubMed2003

Umbilical cord transection in twin-reverse arterial perfusion syndrome with the use of a coaxial bipolar electrode (Versapoint).

Umbilical-cord occlusion has been proposed for the treatment of twin-reverse arterial perfusion syndrome (TRAP). Transection of the umbilical cord is necessary in patients with monoamniotic or 'pseudomonoamniotic' TRAP to avoid subsequent cord entanglement and demise of the pump twin. We present a case of TRAP in which the umbilical cord was successfully ligated with suture and transected with the Versapoint electrode.

Adult↗
PubMed2001

Determination of fipronil by solid-phase microextraction and gas chromatography-mass spectrometry.

A method for the determination of trace amounts of the insecticide fipronil was developed using solid-phase microextraction-gas chromatography-mass spectrometry and selected ion monitoring. Fipronil was extracted with a fused-silica fiber coated with 85 microm polyacrylate. The effects of pH, ionic strength, sample volume, extraction and desorption times as well as the extraction temperature were studied. Lindane was used as an internal standard. The linear concentration range of application was 0.3-100 ng ml(-1) of fipronil, with a relative standard deviation of 9.5% (for a level of 50 ng ml(-1)) and a detection limit of 0.08 ng ml(-1). The method was applied to check the eventual existence of fipronil above this limit in water and soil samples from Granada (Spain) as well as in human urine samples. The method validation was completed with spiked matrix samples. The method can be applied as a monitoring tool for water, soil and urine, in the investigation of environmental and occupational exposure to fipronil.

Gas Chromatography-Mass Spectrometry↗
PubMed2001

Differential-pulse adsorptive stripping voltammetric determination of the antibacterial lomefloxacin.

A differential-pulse adsorptive stripping voltammetric method for the determination of trace amounts of the antibacterial lomefloxacin is proposed. By using an accumulation potential of -0.30 V and a 2 min accumulation time, the linear concentration range of application was 1.0-10.0 ng ml(-1) of lomefloxacin, with a relative standard deviation of 3.8% (for a level of 5.0 ng ml(-1)) and a detection limit of 0.3 ng ml(-1). The method was applied to determination of lomefloxacin in human urine and serum samples. It was validated using HPLC as a reference method. Recovery levels of the method reached 100% in all cases.

Anti-Infective Agents↗
PubMed1999

Analysing organophosphorus pesticides in wines using graphitized carbon black extraction cartridges.

A quick and simple method was developed to determine the residues of 15 organophosphorus pesticides of different polarity in grape wine, based on liquid-solid extraction with graphitized carbon black cartridges and capillary gas chromatography. Aliquots of diluted wine (10 ml wine + 40 ml deionized water) and 250 mg graphitized carbon black cartridges were used to extract the analytes. The pesticides were eluted with 2 x 0.5 ml acetone and 3 x 2.5 ml ethyl acetate/acetone (80:20). The eluates were then dried with anhydrous sodium sulphate and concentrated to 1 ml under a nitrogen current. After adding triphenylphosphate internal standard (i.s.), this extract was analysed by capillary gas chromatography using a nitrogen-phosphorus detector (GC-NPD). Pesticide recovery percentages at levels of 0.01 and 0.02 microgram/ml were between 74% and 111%, with a 2-13% relative standard deviation interval. The chromatograms of extracts had few co-extracted species peaks, with no analytical interference. Dilution of the grape wine samples removed most of the pigments, thus producing clear extracts. The results indicate that liquid-solid extraction from wine samples using graphitized carbon is fast (25 min per sample), efficient and reproducible for analysing organophosphorus pesticides of different polarity.

Chromatography, Gas↗
PubMed1999

Influence of the surfactant concentration on the body distribution of nanoparticles.

The rapid reticuloendothelial system (RES) uptake of nanoparticles after i.v. injection, especially by the liver, can be reduced and the body distribution can be altered by coating them with non-ionic surfactants. In the present work 2-14C-poly(methyl methacrylate) nanoparticles were coated with poloxamine 908 and polysorbate 80, and the influence of different surfactant concentrations on the body distribution was investigated. These surfactants were chosen because earlier studies showed that poloxamine 908 was very effective in decreasing the liver uptake and keeping the nanoparticles in circulation, whereas polysorbate 80 was the most effective surfactant to direct the particles to organs that do not belong to the RES. Above nanoparticles were injected i.v. to rats and the animals were sacrificed after 30 min. Below a surfactant concentration of 0.1% the nanoparticle preparations behaved like uncoated particles. At a 0.1% concentration a very sudden and significant change in the body distribution occurred with poloxamine 908. The liver concentration decreased from about 75% of the dose to 13% and stayed at this level at higher surfactant concentrations. This decrease was combined with a similar sudden complementary increase in blood and other organ and tissue concentrations. With polysorbate 80 the decrease in liver concentration and increase in the blood and the other organ levels was gradual and became important only above 0.5% surfactant concentration. The results indicate that the type of interaction and the strength of the adsorptive binding to the nanoparticles are different with different surfactants. This in turn leads to different body distribution patterns after i.v. injection of surfactant coated nanoparticles.

Animals↗
PubMed1998

Body distribution of azidothymidine bound to hexyl-cyanoacrylate nanoparticles after i.v. injection to rats.

Cells of the reticuloendothelial system (RES e.g. macrophages) play an important role in the immunopathogenesis of AIDS. The objective of the present study was to investigate the possibility of specifically targeting antiviral drugs such as azidothymidine (AZT) to macrophages using nanoparticles as colloidal drug carriers. In a first series of experiments the body distribution of 14C-labelled AZT bound to nanoparticles and a similarly prepared control solution with unbound AZT were studied in rats after intravenous injection. In a second series of experiments polysorbate 80-coated nanoparticles and a solution of AZT in saline were tested. 14C-labelled AZT was bound to nanoparticles using the surfactant bis(2-ethylhexyl) sulphosuccinate sodium (DOSS). The radioactivity in several organs, including those containing large numbers of macrophages, was measured after intravenous injection of the AZT-nanoparticles and the AZT-control solutions. AZT concentrations were up to 18 times higher in organs belonging to the RES if the drug was bound to nanoparticles compared with unbound AZT. These results demonstrate that nanoparticles are a potential drug targeting system for anti-AIDS drugs. The increase in drug concentration at the sites containing abundant macrophages may allow a reduction in dosage to reduce systemic toxicity.

Animals↗
PubMed1997

"Mixed dementia": adequate or antiquated? A critical review.

Despite its importance and widespread usage, the term mixed dementia, referring to the coexistence of Alzheimer's disease (AD) and vascular dementia (VsD), has been ill-defined and poorly conceptualized. The authors review the use of the term mixed dementia in neuropathological and clinical research. As a result of recent developments in the categorization of dementias, they recommend discarding the term mixed dementia in favor of a more precise terminology based on AD and VsD concurrently meeting established criteria for each diagnosis.

Alzheimer Disease↗
PubMed1995

Efficacy of risperidone treatment for psychoses associated with schizophrenia, schizoaffective disorder, bipolar disorder, or senile dementia in 11 geriatric patients: a case series.

BACKGROUND: Clinical trials of risperidone, a recently approved novel antipsychotic, included elderly healthy patients, but more data are needed on the effects of risperidone in this population, especially those with comorbid medical illnesses. METHOD: Risperidone was used to treat 11 elderly hospitalized patients between 61 and 79 years of age who manifested signs of psychoses related to schizophrenia, schizoaffective disorder, bipolar disorder, or senile dementia. All patients had been treated previously with classic antipsychotics. Response was assessed by clinical observation of the patients' behavior. RESULTS: Eight patients responded to treatment, 1 did not respond, and 2 had treatment discontinued because of hypotension or dizziness. Positive and negative symptoms decreased markedly in 7 of the responding patients. Four patients had preexisting extrapyramidal symptoms (EPS) and symptoms of tardive dyskinesia that also decreased in response to risperidone treatment. In addition, 4 patients were able to discontinue anti-parkinsonian medications, and 2 were able to discontinue antihypertensive medications. Side effects related to blockade of dopamine, histamine, and serotonin were negligible. No adverse consequences occurred when electroconvulsive therapy, carbamazepine, or lithium was given concurrently. CONCLUSION: The reduction of both positive and negative symptoms of schizophrenia and the lack of significant EPS, tardive dyskinesia, sedation, and anticholinergic side effects indicate that risperidone is a safe and effective medication for the elderly.

Aged↗
PubMed1994

Effects of aminophylline on cardiac function and regional myocardial perfusion: implications regarding its antiischemic action.

Aminophylline improves exercise capacity in patients with angina. Because this drug does not dilate epicardial coronary vessels, its beneficial effect is from either a reduction of myocardial oxygen consumption or an improvement of myocardial blood flow distribution. This study was performed to assess the effects of aminophylline on cardiac function and on regional myocardial perfusion to establish the mechanisms of its antiischemic action. In 10 patients during cardiac catheterization hemodynamic parameters and cardiac volumes were obtained during baseline and after intravenous infusion of aminophylline. Aminophylline decreased left ventricular end-diastolic pressure (from 11 +/- 4 to 4 +/- 2 mmHg, p < 0.001), mean right atrial pressure (from 5 +/- 2 to 2 +/- 1 mmHg, p < 0.01), and left ventricular end-diastolic volume (from 117 +/- 36 to 88 +/- 36 ml, p < 0.01); it increased peak dp/dt (from 1931 +/- 329 to 2430 +/- 540 mmHg/sec, p < 0.001) and heart rate (from 69 +/- 9 to 76 +/- 14 beats/min, p < 0.05) and did not modify systolic aortic pressure (138 +/- 14 vs 137 +/- 16 mmHg, p = not significant [NS]). Estimated oxygen consumption during aminophylline (6.7 +/- 1.3 ml/min/gm) was similar to that during baseline (6.7 +/- 1.4 ml/min/gm). In another study in nine anesthetized dogs with a critical stenosis of the left anterior descending artery, myocardial perfusion was assessed by microspheres during control atrial pacing and during atrial pacing after aminophylline; left atrial pressure was kept constant throughout the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminophylline↗
PubMed1992

Detection of coronary artery disease with positron emission tomography and rubidium 82.

Myocardial blood flow was evaluated in 31 subjects with not only visual but also, for the first time, circumferential profile analysis of rubidium 82 (82Rb) images acquired with positron emission tomography. Fifteen were control subjects and 16 subjects had significant coronary artery disease, defined as 50% or greater diameter stenosis in a major coronary artery or a first-order branch. Simultaneous 82Rb images at three myocardial levels were obtained before and after intravenous dipyridamole plus handgrip stress. In patients with significant coronary artery disease, visual analysis correctly identified significant disease in 26 (76%) of 34 arteries and its absence in 12 (86%) of 14 normal arteries. According to circumferential profile analysis, these numbers were 91% and 86%, respectively. Thus circumferential analysis of 82Rb images, obtained before and after intravenous dipyridamole plus handgrip stress, yielded improved sensitivity and comparable specificity compared with visual analysis.

Coronary Disease↗
PubMed1991

Effects of oxyfedrine on regional myocardial blood flow in patients with coronary artery disease.

Medical treatment of angina pectoris is largely based on the use of beta-blocking agents, calcium antagonists, and nitrates. Oxyfedrine, an amino ketone derivative and partial agonist at beta receptors, has been shown to have potent antianginal properties and to increase coronary blood flow in normal and ischemic myocardial regions in experimental studies. We assessed the effects of intravenous oxyfedrine on regional myocardial blood flow, using positron emission tomography (15-oxygen water), in six patients with chronic stable angina, positive exercise tests, and documented coronary artery disease. Myocardial blood flow was measured in all patients before (baseline) and 10 minutes after the intravenous administration of a single bolus (0.11-0.13 mg/kg) of oxyfedrine. Compared to baseline, heart rate and systolic blood pressure remained almost unchanged after the administration of oxyfedrine. Mean baseline myocardial blood flow was 0.90 +/- 0.15 ml/g/min in areas supplied by arteries with significant coronary stenosis and 1.08 +/- 0.19 ml/g/min in areas supplied by nonstenotic coronary vessels (p less than 0.05). After the administration of oxyfedrine, myocardial blood flow increased significantly in both the regions supplied by stenotic vessels (by 25%; from 0.90 +/- 0.15 to 1.20 +/- 0.31 ml/g/min; p = 0.002) and in areas supplied by angiographically normal coronary vessels (by 22%; from 1.08 +/- 0.19 to 1.38 +/- 0.49 ml/g/min; p less than 0.05). The results of this study indicate that in patients with coronary artery disease, intravenous oxyfedrine significantly increases regional myocardial blood flow, both in areas supplied by critically obstructed vessels and in areas supplied by normal or less severely narrowed coronary arteries.

Aged↗
PubMed1991

Positron emission tomography demonstrates that coronary sinus retroperfusion can restore regional myocardial perfusion and preserve metabolism.

Positron emission tomography was used to image blood flow and metabolic tracers in risk zone myocardium after left anterior descending coronary artery occlusion during synchronized coronary venous retroperfusion. Six control and seven intervention open chest dogs had occlusion of the mid left anterior descending coronary artery. Synchronized retroperfusion commenced 25 min later. Flow tracers (rubidium-82 and nitrogen-13 ammonia) were injected retrogradely. Three hours after coronary occlusion, fluorine-18 (F-18) deoxyglucose uptake in the control and treatment groups was compared. At 200 min of occlusion, infarct size was assessed. Retrograde flow tracer uptake was observed in the risk zone in the seven intervention dogs. Fluorine-18 deoxyglucose uptake in the risk zone was increased in five of the six intervention dogs but was reduced in five of the six control dogs. The risk zone to normal zone F-18 deoxyglucose count ratio was higher in the intervention than the control group (1.13 +/- 0.39 vs. 0.59 +/- 0.51; p less than 0.05). The endocardial subsegment risk zone to normal zone F-18 deoxyglucose count ratio was also significantly higher in the intervention group. Percent infarction in the risk zone was 70% lower in the group treated with synchronized retroperfusion than in the control group (18.4 +/- 22.6% vs. 61.2 +/- 25.4%; p less than 0.02). Thus, positron emission tomography revealed that retroperfusion could deliver oxygenated blood and maintain metabolism in risk zone myocardium. Infarct size was limited to 30% of that of control. In acute closure of the left anterior descending coronary artery, synchronized retroperfusion might be considered for maintaining viability of the jeopardized myocardium if the artery cannot be reopened rapidly.

Animals↗
PubMed1991

[Obstetric care and perinatal mortality in a rural area of northeastern Brazil].

This paper examines deliveries in a rural community of northeastern Brazil served by midwives who had received training that included the referral of pregnancies with complications; such training is essential to improve obstetrical care in rural areas of less developed countries. Data were collected on 1,661 women, of whom 62% gave birth in their homes and 38% in hospitals. The women referred to hospital were more likely to be primigravidas, to experience complications during labor, or to have had a stillbirth in the past. The parturients who were sent straight to hospital were more likely to have completed primary schooling or to have obtained prenatal care. The infant mortality rate was 32/1,000 births and the early neonatal mortality rate 14/1,000. For referred pregnancies these mortalities rose to 128 and 24, respectively. The factors significantly associated with perinatal mortality were advanced maternal age, the presence of prenatal pathology, abnormal presentation, complications in labor, and previous stillbirth. The low rate of perinatal mortality for young women and nulliparas and the disproportionally high number of nulliparas with deliveries in hospitals suggest that the midwives and health professionals providing prenatal care are aware of the problems associated with the first delivery and hence are providing prompt and appropriate care to these parturients. Family planning is recommended, especially for grand multiparas and older mothers. The early detection of abnormal presentation and the transfer of these women to surgical facilities should improve perinatal prognosis.

Adolescent↗
PubMed1990

A study of infant mortality and causes of death in a rural north-east Brazilian community.

In 1984 a prospective study of 1645 women and 1677 births in a rural community in north-eastern Brazil showed the infant mortality rate to be 65 per 1000 live births. Neonatal, post-neonatal and infant mortality are analysed to determine the most important risk factors for each period. Post-neonatal survival depends largely on factors relating to child care, while neonatal deaths are more likely to be associated with biological factors. The principal cause of death, diarrhoeal disease, was responsible for a third of the deaths.

Brazil↗