Biomedical subjects

M A Duarte

Publications and source records attributed to M A Duarte.

11 recordsLinked to original sources

PubMed2005

Abietanes from Plectranthus grandidentatus and P. hereroensis against methicillin- and vancomycin-resistant bacteria.

The antimicrobial activity of 10 natural abietanes isolated from Plectranthus grandidentatus and P. hereroensis acetonic extract was evaluated against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecalis (VRE). The results revealed that the most active diterpenes were coleon U (1), 7alpha-acetoxy-6beta-hydroxyroyleanone (2) and horminone (3). Minimum inhibitory concentration (MIC) values ranging 0.98-15.63 microg/ml were obtained for MRSA clinical strains, and MIC values of 15.63 and 31.25 microg/ml were obtained for VRE clinical strains. Some structure-activity relationships are emphasized.

Abietanes↗

PubMed2004

Modeling extracellular space electrodiffusion during Leão's spreading depression.

Computational modeling of spreading depression (SD) has been used increasingly to study the different mechanisms that are involved in this phenomenon. One of them that is still under discussion involves the mechanisms that originate the extracellular electrical field responsible for the dc potential shift. The main goal of this paper is to present a mathematical derivation for the extracellular electric field that is incorporated in a SD model that has the basic structure of Tuckwell and Miura's model, but with the ionic variations calculated electrochemically. Electrodiffusion equations were used to describe the ionic movement of the four ions Na+, K+, Cl-, and Ca2+. These are mutually coupled by the electric field within the extracellular space (ECS). The results from the simulations show that the model is able to calculate the effect of the ionic changes along the ECS on the electric field, and to reproduce the SD in respect to the most important features that characterize the phenomenon experimentally in the retina or hippocampus. It is suggested that the extracellular negative field-potential shift during SD is due to an electrical field generated by a Goldman-Hodgkin-Katz equation acting within the ECS.

Action Potentials↗

PubMed2003

Functional imaging of the retinal layers by laser scattering: an approach for the study of Leão's spreading depression in intact tissue.

This paper presents a novel optical approach for the study of spreading depression in isolated retina. The method makes it possible to register the laser light scattered from each layer of the tissue, yielding a functional image of the retina during spreading depression. The tissue is kept intact, since histological cuts are not necessary. Measurements of other variables, such as extracellular potential, are also allowed by the described method. This is done simultaneously with the functional image in a high spatial resolution, with the positioning of the microelectrode tip being easily monitored. The information about temporal and spatial evolution of light was compacted in a single image. The image-processing technique used here enables the visualization of the light scattered by the inner plexiform layer (IPL), which is the most prominent scatter layer during spreading depression. The wavefront velocity and its increase as two wavefronts approach each other can then be determined, and it is also possible to observe the thickness variation of the tissue during the wave travel. The relationship between two peaks of light-scattering sequence during the phenomenon was studied at two wavelengths (632.8 and 543.5 nm). This relationship is shown to be dependent on the wavelength.

Animals↗

PubMed2000

Evaluation of pH and calcium ion release of three root canal sealers.

The pH and calcium ion release of three root canal sealers--Sealapex, Sealer 26, and Apexit--were assessed at 24 and 48 hr, and at 7 and 30 days after spatulation. After manipulation, the sealers were placed in 1-cm-long tubes measuring 4 mm in diameter and immersed in a glass flask containing 10 ml of deionized water, which was hermetically sealed and stored at 37 degrees C. The tubes were removed at the scheduled times and the water in which they were immersed was tested for pH with a pHmeter and for released calcium by atomic absorption spectrophotometry. Starting 48 hr after immersion, Selapex produced an alklaine pH and released significantly higher calcium amounts compared with the other two sealers, with even more pronounced results after 30 days. On the basis of the results obtained, we conclude that Sealapex presented the highest calcium and hydroxyl release, especially after longer time intervals, whereas Sealer 26 showed highest release during the initial periods (i.e. during its setting time). Apexit presented the least satisfactory results.

Analysis of Variance↗

PubMed2000

Pressure pain threshold in children with recurrent abdominal pain.

BACKGROUND: Experimental studies on humans have shown that recurrent pain is associated with altered pain perception. We measured the pressure pain threshold in regions of the body surface in a group of children who had recurrent abdominal pain and in a group of children with chronic or recurrent disease but with no pain. METHODS: Each group consisted of 45 boys and 55 girls ranging in age from 5 to 15.8 years. The regions of the body were the trapezius, deltoid, and supraspinous muscles, nine areas on the abdominal wall, and the median part of the tibias. Using an algometer, pressure was applied through a rubber disc with a surface area of 1 cm2 at a rate of 0.5 kg/cm2/s. The pressure values recorded with the algometer when the children communicated that they started to feel pain were considered as pressure pain thresholds. RESULTS: The pain thresholds were reduced in all regions investigated in children with recurrent pain. The median thresholds for all regions of the patients with and without pain were 1.60 and 2.2 kg/cm2, respectively. The diseases of children with pain did not influence the pain thresholds. CONCLUSION: There was an association between recurrent abdominal pain and a lower pressure pain threshold, with no influence of the type of disease, and there was a central nervous system alteration in the perception of pain in these patients.

Abdominal Muscles↗

PubMed2000

[Recurrent abdominal pain]

OBJECTIVE: To present current concepts about the diagnosis of recurrent abdominal pain and to review the basis of the therapeutic approach for this disease in children and adolescents. METHODS: References were obtained from the Medline, from recent review articles, and from personal files. Books and dissertations were also analyzed. Only the most important articles were included in this review. RESULTS: Recurrent abdominal pain is the main cause of recurrent pain in children between 4 and 16 years of age. It is defined as the occurrence of three or more abdominal pain attacks within 3 months or less. These attacks are severe enough to interrupt routine activities, making the child remain asymptomatic between the episodes of pain. The diagnosis is based on a detailed clinical history, on an improved physical examination, and on a few laboratory tests. It can be manifested with isolated paroxysms of umbilical pain, abdominal pain with dyspeptic symptoms, and abdominal pain with digestive tract dysfunction. The treatment must emphasize the cognitive-behavioral factors of the recurrent pain. CONCLUSIONS: The treatment of recurrent abdominal pain using the strategy presented here represents an equilibrium in which time is neither wasted nor insufficient during the investigative process required for treating children and their families with this problem.

Journal Article↗

PubMed1994

Fecal loss and clearance of alpha-1-antitrypsin in children with persistent diarrhea.

1. Daily fecal loss and daily clearance of alpha-1-antitrypsin were determined in 30 infants without intestinal disorders and in 21 with persistent diarrhea. 2. Stools were collected during a 48-h period and a randomly obtained single sample was also collected. Blood samples were also collected from the infants, and alpha-1-antitrypsin was measured by radial immunodiffusion in both stool and serum. 3. No difference in daily fecal loss (mg/d) of alpha-1-antitrypsin was detected between the control group and the group with persistent diarrhea (11 +/- 9.3 vs 18.5 +/- 20 mg/d). No difference in daily alpha-1-antitrypsin clearance (ml/d) was detected between the control group and the group with persistent diarrhea (4.3 +/- 3.6 vs 5.2 +/- 4.8 ml/d). 4. There was a strong correlation between daily fecal loss and daily clearance of alpha-1-antitrypsin (N = 50). There was a weak correlation between the concentrations of alpha-1-antitrypsin in randomly obtained single samples and daily fecal loss of the antiprotease (N = 25; r = -0.183; P < 0.01). 5. We conclude that: a) there is no increased fecal loss of alpha-1-antitrypsin persistent in diarrhea; b) fecal alpha-1-antitrypsin clearance is not necessary to estimate the enteric loss of the antiprotease; c) the determination of alpha-1-antitrypsin in random samples of feces is not a reliable method.

Diarrhea, Infantile↗

PubMed1989

Chronic calcifying pancreatitis in children: a report of six cases.

1. A study of six patients with Chronic Calcifying Pancreatitis (CCP) occurring over a 10 year period, representing an incidence rate of approximately 1:1,000 of the inpatients in the children's ward of a general hospital in central Brazil, is reported. 2. Major clinical manifestations as well as therapeutic management are described. 3. The possible relationship between CCP and primary protein-calorie malnutrition is discussed and the importance of a CCP diagnosis when dealing with malnourished children who do not respond satisfactorily to common therapy is emphasized.

Calcinosis↗

PubMed1989

Influence of nutritional status, age and sex on infant hair zinc concentration.

1. Zinc concentration was measured in hair samples from 57 infants (27 boys and 30 girls) aged 7 to 24 months. Twenty-eight infants were considered eutrophic and 29 presented chronic and severe malnutrition. 2. Hair segments less than 3-cm long were cut close to the scalp in the occipital area and washed in deionized water and acetone. Zinc levels were measured by neutron-activation. 3. Hair zinc concentration decreased with age in both eutrophic and malnourished infants from 160 micrograms/g at 7 months to 90 micrograms/g at 24 months. 4. No statistically significant difference in hair zinc concentration was detected between eutrophic and malnourished infants (148 +/- 60 vs 128 +/- 57 micrograms/g hair, mean +/- SD) or between sexes.

Age Factors↗

PubMedDate not supplied

[Pain threshold and age in childhood and adolescence]

OBJECTIVE: The few investigations about pressure pain threshold in corporeal surface areas and children age showed no correlation between these parameters in all areas. In this research the existence of correlation between age and pressure pain threshold in seventeen areas of the corporeal surface of children was investigated. METHODS: A descriptive research was made with one hundred children from the Clinical Hospital of the Federal University of Minas Gerais. The selection of patients was made by directed search. There were forty five boys and fifty five girls with ages varying between 5.3 and 15.8 years old, and a mean (-/+ standard deviation) of 9.6 (-/+ 2.7) years old. The seventeen corporeal areas studied were regions of the trapezium, deltoid and supraspinal muscles, nine areas of the abdomen and the median part of the tibias. The pressure of 0.5 kg/cm(2)/s was made using a mechanical algometer. The pressure values that were recorded in the equipment when the children started to complain about the pain, by verbal communication, were considered as pressure pain thresholds. RESULTS: Positive correlations with significant statistic values were found between pressure pain threshold and age in every area investigated: trapezium, r = 0.36; deltoid, r = 0.34; supraspinal, r=0.42; hypochondrium, r=0.41; epigastrium, r=0.41; flank, r = 0.48; periumbilical, r = 0,40; iliac fossa, r = 0.49; hypogastrium, r = 0.45 and tibia, r = 0,29. CONCLUSIONS: Since correlations between age and pressure pain threshold were found in all areas studied, the age of a patient must be taken into consideration during clinical investigations and pain evaluations in children and adolescents. The younger the patient, the lower the pain thresholds.

Journal Article↗

PubMedDate not supplied

[Research on enteropathogenic bacteria from children with acute diarrhea, in Belo Horizonte, MG].

Enteropathogenic bacteria were searched in feces of 80 children with acute diarrhea from the lower social economical level, all of them younger than twenty seven months old, and without any antimicrobial therapy, in Belo Horizonte, MG, Brazil, from June 1981 to August 1982. The following enteropathogenic bacteria were isolated from 46 children: Shigella in 12 children (15.00%), enterotoxigenic Escherichia coli in 12 children (15.00%), classic enteropathogenic Escherichia coli in 9 children (11.25%), Salmonella in 6 children (7.50%). Association of enteropathogenic bacteria were found in 7 children (8.75%). Yersinia enterocolitica and invasive Escherichia coli were not isolated from any patient.

Brazil↗