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Biomedical subjects

A Campos

Publications and source records attributed to A Campos.

At least 73 records · Page 4Linked to original sources
PubMed1998

The captopril renogram: a new tool for diagnosing and predicting obstruction in childhood hydronephrosis.

PURPOSE: We evaluated the difference in response patterns of captopril versus standard renography for assessing hydronephrosis due to suspected ureteropelvic and ureterovesical junction obstruction. This technique may identify hydronephrotic kidneys in which normal function is maintained by vasoactive compensatory mechanisms. Sustained obstruction may cause these mechanisms to fail, and expose the kidneys to permanent functional deterioration in the long term. MATERIAL AND METHODS: We prospectively studied 15 boys and 8 girls with a mean age of 3.5 years with grades III to IV/IV hydronephrosis. Evaluations included renal sonography, standard diuretic and captopril renography, glomerular filtration rate, voiding cystography, serum creatinine, blood pressure, and urinalysis with culture and sensitivity. Obstruction was suspected at the ureteropelvic junction in 19 kidneys and at the ureterovesical junction in 9. We compared differential function values obtained by standard diuretic and captopril renography. RESULTS: We observed certain patterns in response to captopril renography, including pattern 1--unilateral decrease in hydronephrotic kidney relative function in 5 of 23 cases, 2--bilateral decreased function in 2, 3--bilateral increased function in 4 and 4--no change in function in 12 on standard renography. When half-time was more than 20 minutes on standard diuretic renography in 8 cases, captopril renography showed an ipsilateral decrease and bilateral increase in glomerular filtration rate in 4 and 1, respectively, and no change in 3. In 12 of the 23 patients (52%) there was no difference in the results of captopril and diuretic renography as well as no change in differential function on standard diuretic renography during 1 1/2 years of observation. Surgical correction was performed in 4 patients in whom half-time was greater than 20 minutes and differential function was decreased on captopril renography. CONCLUSIONS: Our preliminary study reveals that there may be a role for captopril renography for detecting renin-angiotensin system mediated compensatory mechanisms in obstructive uropathy. When such compensatory mechanisms are activated, they may be unmasked by captopril, producing 1 of 4 patterns on renography and glomerular filtration rate. Patterns may indicate different degrees of impending renal function impairment and, thus, they may become useful for determining the progression of injury, when present, and the appropriate timing of surgical intervention.

Captopril↗
PubMed1998

Study of common aerobic flora of human cerumen.

Cerumen is the product of the secretion of the sebaceous, ceruminous or apocrine glands together with cells exfoliated from the cornified stratum of the epithelium of the external auditory canal (EAC). In the present study we identified and quantified common flora of human cerumen. The mean count obtained was 10(6) microorganisms per ml of cerumen suspension. In 24 pools of cerumen (33.3 per cent) the isolates were monomicrobial, Staphylococcus epidermidis (12), Corynebacterium spp (10), Staphylococcus aureus (1) and Streptococcus saprophyticum (1). In 48 pools (66.6 per cent) we found polymicrobial isolates. The most commonly isolated bacteria in these polymicrobial isolates were S. epidermidis (35) and Corynebacterium spp. (43). It is noteworthy that there were isolates of Candida albicans in three cases; in one case of Pseudomonas stutzeri, in one case of Pseudomonas aeruginosa, and, on seven occasions, of S. aureus. The organisms isolated as common bacterial components of human cerumen in our experience were similar to those found by other authors. However, the mean count was much higher. This could be related to climatic conditions and to the length of time the cerumen had remained in the external auditory canal.

Adolescent↗
PubMed1998

The flagellar switch genes fliM and fliN of Rhodobacter sphaeroides are contained in a large flagellar gene cluster.

In this work, the genes that encode the FliM and FliN proteins of Rhodobacter sphaeroides were characterized. These genes are part of a large flagellar gene cluster in which six additional open reading frames encoding products homologous to FliL, FliO, FliP, FliQ, FliR, and FlhB proteins from other bacteria were identified. The inactivation of the fliM gene gave a nonflagellate phenotype (Fla-), suggesting that FliM is required for flagellar assembly. Complementation analysis of this fliM mutant indicated that fliM and fliN transcription starts beyond the 5' end of fliK and terminates after fliN.

Amino Acid Sequence↗
PubMed1998

Electron probe microanalysis of permanent human enamel and dentine. A methodological and quantitative study.

Sample preparation of dental tissues for quantitative electron microprobe analysis has not been critically examined because of the highly mineralized nature of these structures. The present study was designed to establish the most suitable method for the electron probe quantitative determination of calcium in human permanent enamel and dentine while preserving the morphological features. Comparisons of quantitative data obtained with air-drying and freeze-drying methods showed that calcium in enamel was more accurately measured in specimens prepared with cryopreservation and freeze-drying. No significant differences between the methods tested were found in dentine although cryopreservation and freeze-drying yielded less statistical variability. Moreover this approach did not modify morphological features of interest. We recommend this combination of processing techniques for human permanent teeth not only because it was found the most accurate and least variable in determining calcium concentration, but also because of its potential usefulness in studies of alterations in tooth mineralization.

Calcium↗
PubMed1998

Otoconia biogenesis, phylogeny, composition and functional attributes.

This work consolidates data about these interesting organic crystals of vertebrate inner ears. It addresses 5 aspects of inner ear otoliths not completely understood to date: 1) embryological data that explains the formation of the crystals, 2) the significance of the organic and the inorganic phase of the otolith and the changing patterns of otoconia formation along the evolutionary tree, 3) otoliths contribution for detecting linear acceleration, 4) the effect that altered gravity and aminoglycosides have on the development and adult shape of the crystals, and the evolutionary significance of a changing shape of the crystals from primitive forms (lamprey) to high vertebrate birds and mammals is discussed, 5) functional attributes of the otolithic organs and morphological modifications of the otoliths by physical and chemical insults are presented with an extensive discussion of the most relevant literature published and available to us.

Animals↗
PubMed1998

Vividness of visual and haptic imagery of movement.

This study investigated the relationships between visual and haptic imagery of movement. A total of 338 subjects, all university students aged between 18 and 26 years, completed the Vividness of Movement Imagery Questionnaire, which evaluates capacity for visual imaging, and a modification of this questionnaire, the Vividness of Haptic Movement Imagery Questionnaire, designed to evaluate capacity for haptic imaging. Scores on the two questionnaires were significantly correlated .60.

Adolescent↗
PubMed1998

A measure of visual imaging capacity: a preliminary study.

The capacity to form images is generally measured by means of questionnaires based on self-evaluation, despite the limitations of this approach. Here we describe a new performance-based test, the Vividness of Visual Imagery Test, designed for assessing imaging capacity of adults. There are 21 items, each of which requires the subject first to visualize a certain object, then to choose between a correct and an incorrect description of that object. For 351 university students Cronbach alpha was .58 and validity of the test also requires further work.

Adult↗
PubMed1998

[Urinary tract infections and pregnancy].

Infection of the urinary tract is the most common type of infection in pregnant women, with a prevalence ranging from 5% to 10%. The majority of symptomatic upper urinary tract infections occur in women with pre-existent asymptomatic bacteriuria, due to the changes the urinary tract undergoes during pregnancy. In order to avoid potentially serious complications affecting maternal and fetal health, an early diagnosis followed by immediate and adequate care is mandatory. The authors have developed a procedure protocol based on the retrospective evaluation of all urinary tract infection cases during pregnancy, diagnosed in Dr. Alfredo da Costa Maternity Hospital during the year of 1994. The purpose of this protocol is to make the procedures as uniform and as adequate as possible, thus lowering the probability of complications.

Adolescent↗
PubMed1998

Improvement of the friction behaviour of NiTi orthodontic archwires by nitrogen diffusion.

The lack of low friction coefficient for the NiTi superelastic archwires makes difficult the optimal use of these materials in orthodontic applications. In this study, the decrease of this friction coefficient has been achieved by means of nitrogen diffusion heat treatments. The titanium nitride coating has been characterised by means of optical and scanning electron microscopy. Transformation temperatures, critical stresses, hardness and friction coefficient have been determined. Besides, the metallic ion release studies showed that the titanium nitride coating prevents biodegradation.

Biocompatible Materials↗
PubMed1998

Tumor burden and serum level of soluble CD25, CD8, CD23, CD54 and CD44 in non-Hodgkin's lymphoma.

We studied the value of soluble CD25, CD8, CD23, CD54 and CD44 serum levels as tumor burden markers in lymphoma. Soluble CD25 compared with the others sCD and the usual serum factors (albumin, lactate dehydrogenase, beta 2-microglobulin, uric acid and C-reactive protein), showed the strongest correlation with the Ann Arbor stage and the number of affected localizations. sCD25 level is the most sensitive serum marker for tumor burden in lymphoma.

Antigens, CD↗
PubMed1997

A fluorescence spectroscopy study of the interaction of monocationic quinine with phospholipid vesicles. Effect of the ionic strength and lipid composition.

The interaction of monocationic quinine with zwitterionic dimyristoyl phosphatidylcholine (DMPC) and mixed negatively-charged dimyristoylphosphatidyl glycerol (DMPG)/DMPC small unilamellar vesicles in the liquid-crystalline phase was investigated by steady-state fluorescence spectroscopy at pH 7 and 37 degrees C. The maximum fluorescence emission peak at 383 nm, upon excitation at 335 nm, shifts to lower wavelength and decreases its intensity as the ratio between the total lipid and quinine concentrations increases. This indicates that in the membrane-bound state quinine is in an environment of low polarity, more deeply buried when anionic DMPG is present in the vesicle. For monoprotonated quinine/DMPC system the corresponding association isotherms show that the extension of binding is slightly enhanced as the ionic strength decreases, whereas for mixed DMPG/DMPC vesicles at low ionic strength, the association of the drug is favoured as the percentage of anionic DMPG increases. The binding curves have been quantitatively analyzed by the binding and the partition models including in this latter an activity coefficient, gamma, to account for non ideal quinine interactions. It is demonstrated for both neutral and anionic membranes that the activity coefficient approaches the unity and that the deviation from ideality is mainly due to electrostatic forces.

Benzoquinones↗
PubMed1997

Binding of basic amphipathic peptides to neutral phospholipid membranes: a thermodynamic study applied to dansyl-labeled melittin and substance P analogues.

A thermodynamic approach is proposed to quantitatively analyze the binding isotherms of peptides to model membranes as a function of one adjustable parameter, the actual peptide charge in solution z(p)+. The main features of this approach are a theoretical expression for the partition coefficient calculated from the molar free energies of the peptide in the aqueous and lipid phases, an equation proposed by S. Stankowski [(1991) Biophysical Journal, Vol. 60, p. 341] to evaluate the activity coefficient of the peptide in the lipid phase, and the Debye-Hückel equation that quantifies the activity coefficient of the peptide in the aqueous phase. To assess the validity of this approach we have studied, by means of steady-state fluorescence spectroscopy, the interaction of basic amphipathic peptides such as melittin and its dansylcadaverine analogue (DNC-melittin), as well as a new fluorescent analogue of substance P, SP (DNC-SP) with neutral phospholipid membranes. A consistent quantitative analysis of each binding curve was achieved. The z(p)+ values obtained were always found to be lower than the physical charge of the peptide. These z(p)+ values can be rationalized by considering that the peptide charged groups are strongly associated with counterions in buffer solution at a given ionic strength. The partition coefficients theoretically derived using the z(p)+ values were in agreement with those deduced from the Gouy-Chapman formalism. Ultimately, from the z(p)+ values the molar free energies for the free and lipid-bound states of the peptides have been calculated.

Amino Acid Sequence↗
PubMed1997

Stereological study of acinar growth in the rat parotid gland induced by isoproterenol.

The growth of the rat parotid gland induced by daily treatment with isoproterenol (IPR) for 2 weeks was investigated by stereological methods applied to light microscopy. After 7 days of treatment, the glandular mass presented a 286% growth, with the first 3 days being the period of greatest growth. Total acinar volume exhibited a 363% increase during the period from 0 to 7 days, while acinar-cell volume presented a 468% growth from 0 to 5 days of treatment. On the other hand, total acinar-cell number did not increase during the study period. Thus, under the conditions used, IPR-stimulated gland growth was essentially hypertrophic. However, a significant increase in the number of bipolar and multipolar mitoses was also observed, especially on the third and fifth days of treatment. As no increase in acinar-cell number occurred during growth, the presence of these mitoses suggests that cell death occurred during gland growth. On this basis, bipolar mitoses may occur to replace cells that probably degenerated during treatment, whereas multipolar mitoses may lead to the occurrence of polyploidy.

Animals↗
PubMed1997

Backscattered electron imaging of cultured cells: application to electron probe X-ray microanalysis using a scanning electron microscope.

We report a simple method to study the elemental content in cultured human adherent cells by electron probe X-ray microanalysis with scanning electron microscopy. Cells were adapted to grow on polycarbonate tissue culture cell inserts, washed with distilled water, plunge-frozen with liquid nitrogen and freeze-dried. Unstained, freeze-dried cultured cells were visualized in the secondary and backscattered electron imaging modes of scanning electron microscopy. With backscattered electron imaging it was possible to identify unequivocally major subcellular compartments, i.e. the nucleus, nucleoli and cytoplasm. X-ray microanalysis was used simultaneously to determine the elemental content in cultured cells at the cellular level. In addition, we propose some improvements to optimize backscattered electron and X-ray signal collection. Our findings demonstrate that backscattered electron imaging offers a powerful method to examine whole, freeze-dried cultured cells for scanning electron probe X-ray microanalysis.

Animals↗