Biomedical subjects

A G Rodrigues

Publications and source records attributed to A G Rodrigues.

11 recordsLinked to original sources

PubMed2004

Chemical composition and antifungal activity of the essential oil of Thymbra capitata.

The composition and the antifungal activity of the essential oil of Thymbra capitata on Candida, Aspergillus and dermatophyte strains were studied. Twenty-two samples of the essential oils from the aerial parts of the plant were obtained by hydrodistillation and analysed by GC and GC-MS. All samples are of the carvacrol type, with a high content of carvacrol (60.0 - 65.8 %) and its biogenetic precursors, gamma-terpinene (8.2 - 9.5 %) and p-cymene (6.0 - 7.5 %). The minimal inhibitory concentration (MIC) and the minimal lethal concentration (MLC) were used to evaluate the antifungal activity against Candida (7 clinical isolates and 3 ATCC type strains), Aspergillus (5 clinical isolates, 2 CECT and 2 ATCC type strains) and 5 dermatophyte clinical strains. To clarify its mechanism of action on Candida strains, the inhibition of germ tube and a flow cytometry assay with propidium iodide (PI) were used. The oil exhibited antifungal activity for all the tested strains, particularly for dermatophytes, with MIC values ranging from 0.08 to 0.32 microL/mL. Regarding Candida, concentrations lower than the MIC values prevented germ tube formation. After a short incubation time the cells incorporated quickly PI, meaning that the fungicidal effect is mainly due to direct lesion of the membrane.

Antifungal Agents↗

PubMed2003

Chemical composition and antifungal activity of the essential oil of Origanum virens on Candida species.

The composition and the antifungal activity of the essential oil of Origanum virens on Candida species were studied. The essential oil was obtained from the aerial parts of the plant by hydrodistillation and analyzed by GC and GC-MS. The oil was characterized by its high content of carvacrol (68.1 %) and its biogenetic precursors, gamma-terpinene (9.9 %) and p-cymene (4.5 %). The minimal inhibitory concentration (MIC) and the minimal lethal concentration (MLC) were used to evaluate the antifungal activity against Candida strains (7 clinical isolates and 3 ATCC type strains). The inhibition of germ tube formation and flow cytometry, using the fluorescent probe propidium iodide (PI), were used to evaluate their mechanisms of action. MIC and MLC values were similar for most tested strains, ranging from 0.16 to 0.32 microL/mL. Concentrations lower than MIC values strongly prevent germ tube formation. The fungicidal effect is primarily due to an extensive lesion of the membrane.

Antifungal Agents↗

PubMed2001

Cytometric approach for a rapid evaluation of susceptibility of Candida strains to antifungals.

OBJECTIVE: To achieve a fast and reliable determination of the susceptibility of Candida strains to amphotericin B (Am B), fluconazole (Flu) and 5-fluorocytosine (5-FC), using cytometric methods as an alternative to the classical dilution method. METHODS: Twenty-three clinical isolates of Candida with different susceptibility patterns were treated for 1 h with two concentrations each of Am B (2 and 8 mg/L), Flu (8 and 64 mg/L) and 5-FC (4 and 32 mg/L), followed by staining with three different fluorochromes, under conditions previously defined through an optimisation study. These were 1 mg/L propidium iodide (PI)/10(6) cells for 30 min at 30 degrees C (a marker that only penetrates cells with severe lesions of the membrane); 0.5 microM FUN-1/10(6) cells for 30 min at 30 degrees C (a fluorescent probe which after entering the yeast cell is converted, by metabolically active yeasts, from a diffuse cytosolic pool with a yellow-green fluorescence into red cylindrical intravacuolar structures) and 0.25 microM of JC-1/10(6) cells for 15 min at 37 degrees C (a monomer that changes reversibly from green to red the J-aggregates, with the increased membrane potential). About 50 000 yeast cells were analysed by flow cytometry (FCM), at FL3 (red, 620 nm) for PI and FL2 (yellow-green, 575 nm) for FUN-1 and the ratio of FL3 to FL1 was determined (red, 620 nm/green, 525 nm) for JC-1; 200 cells of each suspension were also analysed by epifluorescence microscopy (EPM). Viability studies were performed in parallel to count the number of colony forming units. RESULTS: Susceptible (S) strains exposed to Am B and stained with JC-1 showed a dose-dependent decrease in the mitochondrial potential, i.e. a decreased ratio between red/green fluorescence by FCM and a decrease in J-aggregates by EPM. Neither FUN-1 nor PI was useful in the study of Am B activity. Susceptibility to Flu and 5-FC could be detected with FUN-1 staining: metabolic changes were detected by an increase in yellow-green intensity of fluorescence by FCM or a decrease of cylindrical intravacuolar structure formation by EPM, although no decrease in total viability was registered. Staining with JC-1 could predict resistance to both drugs, but did not allow distinction between sensitive dose-dependent strains (S-DD) or intermediate (I) resistance to Flu or 5-FC, respectively, from S strains. PI did not stain Candida cells treated with Flu or 5-FC under our experimental conditions. CONCLUSION: Susceptibility patterns of Candida strains to Am B can be determined by using JC-1, and to Flu and 5-FC by using FUN-1. PI was not a useful probe with which to study the effect of such antifungals under the conditions described here.

Antifungal Agents↗

PubMed2000

Antifungal activity of local anesthetics against Candida species.

OBJECTIVE: To evaluate the activity of benzydamine, lidocaine, and bupivacaine, three drugs with local anesthetic activity, against Candida albicans and non-albicans strains and to clarify their mechanism of activity. METHODS: The minimal inhibitory concentration (MIC) was determined for 20 Candida strains (18 clinical isolates and two American Type Culture Collection strains). The fungistatic activity was studied with the fluorescent probe FUN-1 and observation under epifluorescence microscopy and flow cytometry. The fungicidal activity of the three drugs was assayed by viability counts. Membrane alterations induced in the yeast cells were evaluated by staining with propidium iodide, by quantitation of intracellular K+ leakage and by transmission electron microscopy of intact yeast cells and prepared spheroplasts. RESULTS: The MIC ranged from 12.5-50.0 microg/mL, 5.0-40.0 mg/mL, and 2.5-10.0 mg/mL for benzydamine, lidocaine, and bupivacaine, respectively. The inhibitory activity of these concentrations could be detected with the fluorescent probe FUN-1 after incubation for 60 minutes. A very fast fungicidal activity was shown by 0.2, 50, and 30 mg/mL of benzydamine, lidocaine, and bupivacaine, respectively. CONCLUSIONS: At lower concentrations, the tested drugs have a fungistatic activity, due to yeast metabolic impairment, while at higher concentrations they are fungicidal, due to direct damage to the cytoplasmic membrane.

Agar↗

PubMed1999

Germ tube formation changes surface hydrophobicity of Candida cells.

Hydrophobic interaction is generally considered to play an important role in the adherence of microorganisms to eukaryotic cells and also to certain inert surfaces. Using a microbe adhesion assay to hydrocarbons (n-hexadecane), 68 strains of Candida albicans and 30 non-albicans strains were studied. Influence of source of isolate, age of the culture, and percentage of germ tube formation on adhesion were studied. C. albicans blastoconidia were found to be hydrophilic; conversely, blastoconidia of non-albicans strains were slightly more hydrophobic. Germ tube formation was associated with a significant rise in cell surface hydrophobicity.

Candida↗

PubMed1999

Is the lack of concurrence of bacterial vaginosis and vaginal candidosis explained by the presence of bacterial amines?

OBJECTIVE AND STUDY DESIGN: We report for the first time an inhibitory effect on cell division and germ tube formation by Candida albicans and strains of other Candida species by putrescine and cadaverine. RESULTS: Both bacterial amines showed a dose-dependent inhibition of germ tube formation by C albicans, as well as budding (inhibition of cell division) of strains of other Candida species (ie, C glabrata, C krusei, and C tropicalis). CONCLUSIONS: We hypothesize that the presence of these and possibly other bacterial amines produced by anaerobes in the vaginal flora and seen in bacterial vaginosis, as in the healthy gut, may explain why candidosis is rarely seen in these instances.

Bacteria↗

PubMed1997

Transthoracic echocardiographic assessment of periprosthetic mitral regurgitation using intravenous injection of sonicated albumin.

Mechanical prostheses induce artifacts that decrease the accuracy of conventional transthoracic echocardiographic imaging for the detection and quantitation of periprosthetic mitral regurgitation. In 15 patients undergoing transthoracic echocardiography, injection of sonicated albumin significantly enhanced the assessment of periprosthetic mitral regurgitation with an accuracy similar to that of transesophageal echocardiography.

Adult↗

PubMed1997

Simultaneous determination of aortic valve area by the Gorlin formula and by transesophageal echocardiography under different transvalvular flow conditions. Evidence that anatomic aortic valve area does not change with variations in flow in aortic stenosis.

OBJECTIVES: The purpose of this study was to determine the impact of changes in flow on aortic valve area (AVA) as measured by the Gorlin formula and transesophageal echocardiographic (TEE) planimetry. BACKGROUND: The meaning of flow-related changes in AVA calculations using the Gorlin formula in patients with aortic stenosis remains controversial. It has been suggested that flow dependence of the calculated area could be due to a true widening of the orifice as flow increases or to a disproportionate flow dependence of the formula itself. Alternatively, anatomic AVA can be measured by direct planimetry of the valve orifice with TEE. METHODS: Simultaneous measurement of the planimetered and Gorlin valve area was performed intraoperatively under different hemodynamic conditions in 11 patients. Left ventricular and ascending aortic pressures were measured simultaneously after transventricular and aortic punctures. Changes in flow were induced by dobutamine infusion. Using multiplane TEE, AVA was planimetered at the level of the leaflet tips in the short-axis view. RESULTS: Overall, cardiac output, stroke volume and transvalvular volume flow rate ranged from 2.5 to 7.3 liters/min, from 43 to 86 ml and from 102 to 306 ml/min, respectively. During dobutamine infusion, cardiac-output increased by 42% and mean aortic valve gradient by 54%. When minimal flow was compared with maximal flow, the Gorlin area varied from (mean +/- SD) 0.44 +/- 0.12 to 0.60 +/- 0.14 cm2 (p < 0.005). The mean change in Gorlin area under different flow rates was 36 +/- 32%. Despite these changes, there was no significant change in the planimetered area when minimal flow was compared with maximal flow. The mean difference in planimetered area under different flow rates was 0.002 +/- 0.01 cm2 (p = 0.86). CONCLUSIONS: By simultaneous determination of Gorlin formula and TEE planimetry valve areas, we showed that acute changes in transvalvular volume flow substantially altered valve area calculated by the Gorlin formula but did not result in significant alterations of the anatomic valve area in aortic stenosis. These results suggest that the flow-related variation in the Gorlin AVA is due to a disproportionate flow dependence of the formula itself and not a true change in valve area.

Adrenergic beta-Agonists↗

PubMedDate not supplied

Aneurysm of the membranous ventricular septum and accessory valvular tissue causing obstruction of the pulmonary outflow tract in corrected transposition.

Aneurysm of the membranous portion of the ventricular septum and accessory valvular tissue are two infrequent congenital lesions. This case illustrates a rare association of aneurysm of the membranous septum and accessory valvular tissue originating from the mitral valve, causing right-sided ventricular outflow tract obstruction in a patient with corrected transposition. Multiplane transesophageal echocardiography allowed for determination of the dual nature of the obstruction.

Adult↗

PubMedDate not supplied

Angiosarcomas of the interatrial septum mimicking atrial myxomas.

Angiosarcoma of the heart is a rare tumor. This tumor is most frequently located in the right atrium and pericardium. Localization of a tumor in the interatrial septum usually suggests atrial myxoma. We report two cases of angiosarcoma originating from the interatrial septum, one extending into the right atrium and the other into the left atrium, mimicking atrial myxomas. Transesophageal echocardiography allowed the diagnosis and comprehensive assessment of compromised structures.

Aged↗

PubMedDate not supplied

[Cryptorchism: basic concepts and hormonal therapy].

The authors analyze the clinical results of 368 cryptorchid testis that received intramuscular human chorionic gonadotropin (HCG), at the dose of 50 U/kg once a week for 6 weeks. The patients with inguinal anatomical abnormalities or only with subtle retractility were excluded. There was a correlation among the testicle position, the cryptorchism side, the patient's age at the time of the therapy and the results obtained. We observed (i) a delay on child referral; (ii) concurrence of cryptorchism and systemic diseases, most of them with genetical origin; (iii) better results was obtained in children with retractile testis, older than 4 years old and with bilateral cryptorchism. The efficacy of second hormonal treatment was only present in retractile testis that showed partial response to the first hormonal therapy. It is argued that, although the treatment of children under 2 is less effective, the possible prevention of testicular lesions for this early intervention justify the hormonal therapy between 6 and 9 months of life.

English Abstract↗