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Biomedical subjects

A Antunes

Publications and source records attributed to A Antunes.

18 recordsLinked to original sources
PubMed2006

Spectroscopic alterations on enamel and dentin after nanosecond Nd:YAG laser irradiation.

Laser irradiation on hard tissue has produced a resistant surface that is likely to prevent caries. In this study, human enamel and dentine were exposed to nanosecond pulsed Nd:YAG laser with energy densities of 20-40 J/cm(2) and pulse width of 6 ns inducing chemical changes in these tissues. Infrared analysis of human dental enamel and dentine was performed using the KBr method (2mg sample/300 mg KBr). A correlation between non-lased and lased spectra was performed that gives an indication of the changes in organic and inorganic compounds after laser-tissue interaction. Spectra of teeth simultaneously show the inorganic and organic parts of the tissue. The principal bands: amide bands A, I, II, and III from the collagen-matrix, phosphate from the mineral content, and carbonate bands were identified. The normalized area of peak versus peak position was determined. Changes of the bands attributed to the collagen matrix were verified after Nd:YAG irradiation. The present results suggest a chemical modification of organic and mineral compounds by laser. The spectral results indicated an alteration in the absorption bands relative to, essentially, organic compounds.

Dental Enamel↗
PubMed2006

Analysis of the healthy rabbit lens surface using MAC Mode atomic force microscopy.

In this investigation healthy rabbit crystalline lenses were characterized by atomic force microscopy (AFM). The lenses were cut in slices with thickness with 1mm and thus, put after cortex distinct regions of nucleus and cortex for AFM examination. AFM analysis were carried out using a PicoSPM I operating in Mac Mode. We obtained topographic images of rabbit lenses and a quantitative analysis of the width and height of fibers for nucleus and cortex regions. The longitudinal section analysis of fibers in the nucleus region indicated structures with an average width of 200nm and average height of 200nm. The intershells distance was determined as 4microm. Fiber cell cross-section dimensions, longitudinal and transverse widths, could be estimated in these regions from the AFM images. Structures with average widths as small as 1.0microm are observed in the nucleus; the intershell distance is 4.0microm. In cortical regions, hexagonal structures with average longitudinal and transverse widths of 5.0mum and 3.0mum, respectively, were identified. Three-dimensional images of tissue sections with resolution on a nanometer scale were obtained. The potential of AFM analysis for characterizing healthy and pathologic lens tissues is discussed.

Animals↗
PubMed2005

Molecular characterisation of a versatile peroxidase from a Bjerkandera strain.

The cloning and sequencing of the rbpa gene coding for a versatile peroxidase from a novel Bjerkandera strain is hereby reported. The 1777 bp isolated fragment contained a 1698 bp peroxidase-encoding gene, interrupted by 11 introns. The 367 amino acid-deduced sequence includes a 27 amino acid-signal peptide. The molecular model, built via homology modelling with crystal structures of four fungal peroxidases, highlighted the amino acid residues putatively involved in manganese binding and aromatic substrate oxidation. The potential heme pocket residues (R44, F47, H48, E79, N85, H177, F194 and D239) include both distal and proximal histidines (H48 and H177). RBP possesses potential calcium-binding residues (D49, G67, D69, S71, S178, D195, T197, I200 and D202) and eight cysteine residues (C3, C15, C16, C35, C121, C250, C286, C316). In addition, RBP includes residues involved in substrate oxidation: three acidic residues (E37, E41 and D183)--putatively involved in manganese binding and H83 and W172--potentially involved in oxidation of aromatic substrates. Characterisation of nucleotide and amino acid sequences include RBP in versatile peroxidase group sharing catalytic properties of both LiP and MnP. In addition, the RBP enzyme appears to be closely related with the ligninolytic peroxidases from the Trametes versicolor strain.

Base Sequence↗
PubMed2005

[Natural history of fetal pyelocaliectasia].

INTRODUCTION: It is estimated that genitourinary anomalies comprise 20% of all antenatally detected fetal anomalies, and pyelocaliectasia is the most common one. Detection of antenatal dilatation of the urinary tract does not always indicate postnatal urinary tract obstruction or even a significant genitourinary anomaly. Most cases will improve spontaneously, representing a temporary physiologic impedence and do not require surgery. MATERIALS AND METHODS: In a two-year period we studied 197 newborns, with prenatal pyelocaliectasia, without concomitant anomaly, delivered at Maternidade Dr. Daniel de Matos. In the postnatal follow-up period, the infants were followed at Pediatrics Department, at our Center. RESULTS: A male predilection was found. Ultrasonic follow-up of the 197 infants showed that pyelocaliectasia resolved in 97%, while 3% still presented it in the postnatal ultrasound. Complementary renal evaluation, with voiding cystourethrography and radionuclide imaging, was realised in 29 (15%) infants to further characterize the abnormality detected in postnatal ultrasound. Surgery was performed in four (2%) children. CONCLUSION: Prenatally diagnosed pyelocaliectasia may be safely observed, and surgical correction should be performed only if renal compromise occurs.

Clinical Protocols↗
PubMed2003

[Lethal neurological involvement during incontinentia pigmenti].

INTRODUCTION: We present a case of incontinentia pigmenti associated with lethal neurological involvement. CASE REPORT: A newborn, three day-old female child presented with an erythromatous vesicular eruption and epileptic seizures secondary to extensive necrosis of the brain tissue. She died at 13 days of age following a seizure. The genetic analysis concluded in a sporadic case of incontinentia pigmenti. DISCUSSION: Thirty-eight cases of incontinentia pigmenti, associated with severe brain damage have been reported in the literature. The neurological manifestations appear rapidly after birth in the form of epilepsy. The seizures can lead to severe psychomotor retardation and, in most cases, precede the installation of motor deficiency. The lesions observed on imaging are hypodensity of varying localization and which do not correspond to any vascularization pattern. Autopsy reveals areas of brain tissue destruction. Recent genetic data suggest two physiopathological hypotheses, which both rely on NF-Kb dysfunction. The cutaneous cells expressing muted chromosome x exhibit a reduced rate of free NF-kB and are more sensitive to the apoptotic signals. Like the cutaneous cells, the brain tissue cells expressing muted chromosome x may be eliminated when becoming apoptotic. Furthermore, NF-kB is one of the links of the transduction system of the messages received by the VEGF receptor, the endothelial growth factor. A perturbation of the transmission of this message might alter cerebral microvascularization.

Brain Diseases↗
PubMed2001

[Mitral flow propagation velocity assessed with M-mode color Doppler in patients with dilated cardiomyopathy].

BACKGROUND: The role of diastolic disfunction in the setting of severe left ventricular (LV) disfunction is usually forgotten due to difficulties in quantification and interpretation. The propagation velocity (PV) of mitral inflow into the left ventricle has been proposed as a load independent indicator of LV diastolic function. Our aim was to correlate PV with age, body surface, chambers dimensions, wall thickness and with classic parameters of systolic and diastolic function. We had in mind the validation of this index in the quantification of LV filling and in risk stratification of patients with dilated cardiomyopathy (DC). MATERIAL AND METHODS: We prospectively studied 32 consecutive patients, mean age 56.1 +/- 15.7 years, 22 (68.75%) male, mean ejection fraction 28.1 +/- 7.5%. All of them were in NYHA class < or = II and on ACE inhibitors. Eight (25%) were on beta-blockers. Patients without sinus rhythm, paced or with significant hypertensive, congenital or valvular heart disease were previously excluded. The following parameters of LV systolic function were assessed by echocardiography: fractional shortening, ejection fraction and cardiac output. LV filling was assessed by transmitral flow pulsed Doppler analysis: isovolumic relaxation time (IVRT), peak E and A wave velocities, E wave deceleration time (DT). We also evaluated a new Doppler index of combined systolic and diastolic myocardial performance (Tei index). PV (cm/s) was calculated by Color M-mode. Univariate regression analysis was performed (PV as dependent variable). RESULTS: We detected a high prevalence of diastolic function disturbances: 25 (78.1%) patients with a delayed relaxation pattern and only 3 (9.4%) with a restrictive pattern. PV did not correlate with age, body surface and LV geometry. There was a significant correlation between PV and E/A ratio (r = 0.61; p < 0.0001), IVRT (r = -0.50; p = 0.006), DT (r = -0.41; p = 0.01) and Tei index (r = -0.36; p = 0.04). CONCLUSIONS: Our results indicate that, in patients with a predominance of delayed relaxation, there is a strong relationship between PV and the classic parameters of LV filling. For similar levels of systolic impairment, PV could be an easy, fast and reproducible quantitative indicator of severity on DC.

Cardiomyopathy, Dilated↗
PubMed2001

Biventricular pacing--early experience.

INTRODUCTION: Biventricular pacing has been studied for the treatment of chronic heart failure (CHF). This technique seems to be able to improve symptoms and exercise tolerance, in patients with advanced CHF and prolonged QRS duration. OBJECTIVE: To present our experience with biventricular pacing in the management of severe CHF. METHODS: Between June 2000 and March 2001, 8 patients with dilated cardiomyopathy and left bundle branch block (LBBB) were selected for transvenous biventricular pacing system implantation. Mean age: 54.12 +/- 16.8 years; 5 males. The etiology was: idiopathic in 6 cases; operated congenital heart disease in 1, and ischemic in the other. Despite tailored treatment of CHF (with all patients taking diuretics and angiotensin-converting enzyme inhibitors), 7 patients remained in NYHA class III and 1 in IV. The quality of life score (assessed by the "Minnesota living with heart failure questionnaire") was 62.25 +/- 11.29. Seven patients had sinus rhythm and only one chronic atrial fibrillation; mean PQ duration--220 +/- 76.37 ms; mean QRS duration--168.75 +/- 20.31 ms. RESULTS: Implant failure, due to coronary sinus dissection and to excessive fluoroscopy time, with no coronary sinus catheterization, occurred in 2 cases (success rate: 75%). Implant data: mean implant procedure duration: 122.5 +/- 47.82 min; mean fluoroscopy time: 35.66 +/- 22.06 min; QRS duration, after implant: 133.33 +/- 15.05 ms. Left ventricular lead final position: anterolateral in 2 patients and lateral in 4. Pacing thresholds: biventricular--1.36 +/- 0.6 V; right ventricle--0.28 +/- 0.04 V; right atrium--0.32 +/- 0.08 V. Pacing impedance (left ventricle): 1013.33 +/- 147.87 omega. Follow-up (1st and 3rd month): one patient died, suddenly, 15 days after the procedure. In the others, an improvement in the quality of life index and functional class was found. These results were independent of echocardiography data. There were no significant differences in the pacing threshold and impedance during the follow-up. CONCLUSIONS: Patients with advanced CHF and widened QRS benefited from biventricular stimulation, in which improvement on the clinical status was evident.

Adolescent↗
PubMed2001

[Pseudoainhum in lamellar ichthyosis].

INTRODUCTION: Pseudoainhum is an affection characterized by the appearance of a constricting band around a digit or limb which may lead to spontaneous amputation. There are various etiologies which can be either congenital or resulting from a concomitant disease. We report herein an original case which occurred during lamellar ichthyosis. CASE-REPORT: We present the case of a thirty-year-old woman affected by a severe form of lamellar ichthyosis who, in a few months, developed a pseudoainhum of the third left finger. Biological results were normal. X-rays of this finger showed distal resorption of the bone. The painful evolution and the absence of any conservative treatment compelled us to propose amputation of the third phalanx. DISCUSSION: Other cases of pseudoainhum have been observed in many disease responsible for vascular or neurological abnormalities. They can also result in physical traumatisms or be associated with many dermatoses, such as hereditary palmar and plantar keratodermas. As far as we know, this lesion has never been described during lamellar ichthyosis but could result in the keratinization disorders observed in this congenital ichthyosis.

Adult↗
PubMed2000

A highly polymorphic plasma protein locus in brown trout (Salmo trutta L.) populations from Portugal.

Genetic polymorphism of an unidentified plasma protein (PX) is described for the first time in Salmo trutta (L.) by means of isoelectric focusing. The analysis of 414 individuals from different geographic origins in Portugal allowed the identification of nine alleles. Heterozygosity in natural populations is generally above 0.60, thus giving similar values to those reported for brown trout microsatellite loci. Substructuring of Portuguese brown trout is evident between northern and southern basins. Genetic affinities between the southernmost rivers and the hatchery stock were detected, suggesting the existence of recent stocking influences.

Animals↗
PubMed2000

Mitochondrial haplotype diversity among Portuguese brown trout Salmo trutta L. populations: relevance to the post-pleistocene recolonization of northern Europe.

Mitochondrial haplotype diversity in seven Portuguese populations of brown trout, Salmo trutta L., was investigated by sequencing the 5' end of the mitochondrial DNA (mtDNA) control region. Five new haplotypes were described for this species, each two to three mutational steps distant from the common north Atlantic haplotype. Significant population subdivision of mtDNA haplotypes was also apparent. Based on these results, as well as on published data describing the distribution of both mtDNA haplotypes and allozyme alleles throughout Europe, the postglacial recolonization of northern Europe was re-evaluated. It is argued that the available data do not support the contribution of two major glacial refugia (southwest Atlantic and Ponto-Caspian Basin) to this postglacial recolonization, as proposed in a recently published model. The unique genetic architecture of Portuguese brown trout within the Atlantic-basin clade of this species represents a highly valuable genetic resource that should be protected from introgression with nonendemic strains of hatchery fish.

Animals↗
PubMed1984

Growth of Trypanosoma cruzi epimastigotes controlled by shifts in cyclic AMP mediated by adrenergic ligands.

Intracellular levels of cAMP in Trypanosoma cruzi epimastigotes were determined in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine, and in the presence of the adrenergic ligand isoproterenol. An increase in the levels of cAMP was observed when those drugs were added. This effect was more pronounced when the cells were in the lag phase of growth. Phosphodiesterase inhibitors, catecholamines and dibutyryl cAMP inhibited proliferation of the organisms, as well as [3H]thymidine incorporation in in vitro experiments. These findings strongly suggest that cAMP plays a role in the control of growth of T. cruzi. The effects of adrenergic ligands in increasing cAMP levels and inhibiting growth could be reversed by beta-adrenergic antagonists, suggesting the presence of a receptor-mediated adenylate cyclase system in T. cruzi. Cholinergic ligands had no effect.

1-Methyl-3-isobutylxanthine↗
PubMedDate not supplied

[Minocycline hypersensitivity syndrome].

BACKGROUND: Drug-induced hypersensitivity syndrome is an uncommon drug reaction typically manifested by severe skin lesions, fever, nodal enlargement, blood eosinophilia and hepatitis. CASE REPORT: A 16-year-old female patient with acne was treated with minocycline 100 mg/d for one month. She developed a hypersensitivity syndrome with a generalized pustulous eruption. Prick tests with minocycline diluted in vaseline were positive at 48 hours. DISCUSSION: This case of minocycline-induced hypersensitivity illustrates that prick tests performed late after the initial event can reproduce the initial lesions. The causal role of several drugs, particularly anticonvulsants, has been demonstrated in drug-induced hypersensitivity syndrome. Several recent publications have implicated minocycline. Although such cases are uncommon, it would appear that cyclines, particularly minocycline, are the main cause of conditions such as drug-induced hypersensitivity syndrome, acute systemic lupus erythematosus, pulmonary eosinophil infiltration, and pseudo-serum sickness. Such secondary effects must be recognized. Patients should be advised to discontinue treatment and consult if signs such as fever, node enlargement, joint pain, or skin reactions reappear. It may be useful to perform prick tests with minocycline 4 to 6 weeks after an initial eruption.

Adolescent↗
PubMedDate not supplied

[Oral health in pregnancy].

Descriptive study with an analytic component, on pregnant women that went for consultation to Maternidade Daniel de Matos (Coimbra, Portugal) during the second week of July 1997. 80 women were randomly selected and asked to answer a questionnaire, concerning level of knowledge towards oral health as well as dietary and oral hygiene habits before and during pregnancy. It was also quantified the dental plaque indicator by using a plaque staining method. The knowledge about oral health is globally speaking, insufficient; dietary habits are mainly cariogenic although pregnant women tend to lower their sugar intake. During pregnancy women rarely go to see the dentist, especially the less educated ones. The dental plaque levels are globally high, indicating oral hygiene habits of low quality.

Adult↗