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Biomedical subjects

L Soares

Publications and source records attributed to L Soares.

17 recordsLinked to original sources
PubMed2005

Conservation implications of complex population structure: lessons from the loggerhead turtle (Caretta caretta).

Complex population structure can result from either sex-biased gene flow or population overlap during migrations. Loggerhead turtles (Caretta caretta) have both traits, providing an instructive case history for wildlife management. Based on surveys of maternally inherited mtDNA, pelagic post-hatchlings show no population structure across the northern Atlantic (phi(ST) < 0.001, P = 0.919), subadults in coastal habitat show low structure among locations (phi(ST) = 0.01, P < 0.005), and nesting colonies along the southeastern coast of the United States have strong structure (phi(ST) = 0.42, P < 0.001). Thus the level of population structure increases through progressive life history stages. In contrast, a survey of biparentally inherited microsatellite DNA shows no significant population structure: R(ST) < 0.001; F(ST) = 0.002 (P > 0.05) across the same nesting colonies. These results indicate that loggerhead females home faithfully to their natal nesting colony, but males provide an avenue of gene flow between regional nesting colonies, probably via opportunistic mating in migratory corridors. As a result, all breeding populations in the southeastern United States have similar levels of microsatellite diversity (H(E) = 0.70-0.89), whereas mtDNA haplotype diversity varies dramatically (h = 0.00-0.66). Under a conventional interpretation of the nuclear DNA data, the entire southeastern United States would be regarded as a single management unit, yet the mtDNA data indicate multiple isolated populations. This complex population structure mandates a different management strategy at each life stage. Perturbations to pelagic juveniles will have a diffuse impact on Atlantic nesting colonies, mortality of subadults will have a more focused impact on nearby breeding populations, and disturbances to adults will have pinpoint impact on corresponding breeding populations. These findings demonstrate that surveys of multiple life stages are desirable to resolve management units in migratory marine species.

Analysis of Variance↗
PubMed2001

[Deciding about pacing mode in sinus node dysfunction: should carotid sinus massage be performed and in which circumstances?].

OBJECTIVE: To state the incidence of carotid sinus syndrome (CSS) with atrioventricular node manifestation in patients with sinus node dysfunction (SND) and indication for a definitive pacemaker (PM), we propose a new protocol between atrial pacing AAI and double chamber DDD. POPULATION AND METHODS: 69 patients (PTS) (male 71%), median age 65 +/- 10 years, with SND (normal PQ and no intraventricular conduction defect), that had a PM implant following the protocol that included carotid sinus massage for the pacing decision, were followed prospectively between December 1995 and November 1999. During the protocol we implanted DDD PM in PTS with Wenckebach less than 130 or Wenckebach equal/over 130 and CSS. At least, in PTS with Wenckebach equal/over 130 and no CSS we implanted AAI PM. The follow-up was between 4 months and 4 years, with clinical evaluation in the first and fourth months and then half yearly, with carotid sinus massage in the first evaluation. RESULTS: About 1/4 of the 69 patients followed had SND without carotid sinus syndrome, or atrioventricular node repercussion; the SND involved the atrioventricular node in 56% of the patients, and there was a relation between the SND and carotid sinus syndrome in 18.8%. The follow-up revealed, in all patients, a complete remission of the symptoms, and when we repeated the carotid sinus massage in the first evaluation, there was a response like in the surgery room, in all patients. CONCLUSIONS: There is a significant number of patients with SND and carotid sinus syndrome. The carotid sinus massage performed in the surgery room does not influence the test sensitivity and specificity in the diagnosis of carotid sinus syndrome. The authors think that carotid sinus massage should be considered in the protocol that defines the pacing mode, in patients with SND, and that influence the choice of pacemaker in 18.8% of patients.

Aged↗
PubMed2000

Relationship between semantic paraphasias and related nonverbal factors.

Word-finding deficits are a common problem in aphasic patients. One hypothesis suggests that the difficulty that patients experience in naming objects or pictures is related to a disruption in the ability to access the lexicon. Another hypothesis suggests that these problems are caused by a disruption of the mental dictionary and the semantic representations contained in it. The main purpose of this study is to assess whether nonverbal factors such as the ability to distinguish between similar attributes of objects is related to word-use problems in aphasia. 14 adults with left hemisphere cerebrovascular accidents and some word use deficit were administered the first 30 items of the Boston Naming Test and the Conceptual Matching subtest of the Detroit Test of Learning Aptitude. Errors on the Conceptual Matching subtest correlated significantly with the number of semantic paraphasias.

Adult↗
PubMed2000

Myocardial architecture, texture and left ventricular heterogeneity in the pulsed Doppler tissue imaging pattern.

The regional contribution for the global ventricular functional performance is complex and heterogeneous, the myocardial texture could reflect this particular aspect, during the phases of myocardial contraction and relaxation. The objective of our clinical study was to evaluate the relationship between the segmental myocardial velocity pattern by Doppler tissue imaging and the ultrasound characteristics of the left ventricular myocardium analysed by computerized ultrasound densitometry with the calculation of its intensity (dB), in a population of 22 subjects without clinical history of cardiovascular pathology, 50% female gender, mean age 43 +/- 11 years (19-66 years). In the methodology of study, the left ventricular myocardium was divided in 16 segments, according with the transthoracic echocardiographic recommendations of the American Society of Echocardiography (A.S.E.). During one cardiac cycle interval, the ultrasound characteristics of the left ventricular myocardium were evaluated continuously and in a quantitative manner, applying the computerized ultrasound densitometry method on the gray scale images of the ventricular myocardium, with the sample size identical to the myocardial wall thickness. The peak (Vmax-cm/sec) and mean (Vm-cm/sec) pulsed Doppler tissue imaging velocities, individuals, segmental and a total velocities, contraction and relaxation velocities of the left ventricular myocardium were obtained immediately after the computerized ultrasound densitometry analysis. Ultrasound densitometry and Doppler tissue imaging data were obtained in a total number of 352 left ventricular myocardial segments. Using the multiple linear correlation matrix analysis, the ultrasound intensity registered inverse significant correlation's with the Doppler tissue imaging Vmax and Vm for the systolic "s" wave in the total segments and each one of them (r = -0.66; p = 0.001; interval 2-18 cm/sec; r = -0.52 to -0.70) and with the early diastolic "e" wave (r = -0.42; p = 0.01; interval 2-19 cm/sec; r = -0.35 to -0.55). Direct correlation's were obtained for the computerized ultrasound densitometry intensity and Doppler tissue imaging Vmax and Vm of the late diastolic "a" wave in the total number of the left ventricular myocardial wall segments and in each one of them (r = 0.51; p = 0.01; interval 1-17 cm/sec; r = 0.42 a 0.66). We conclude that in our study and under physiological conditions of myocardial performance, a direct correlation was obtained between the ultrasound characteristics of the ventricular myocardial imaging and its velocities of contraction and relaxation. These facts reflect the close relationship between left ventricular myocardial structure and function, analyzed by the new ultrasound Doppler technologies.

Adult↗
PubMed1999

Spontaneous ovarian hyperstimulation and primary hypothyroidism with a naturally conceived pregnancy.

BACKGROUND: Ovarian hyperstimulation syndrome, not related to ovulation induction, is rare. A MEDLINE search from 1987 to 1997 using the key words "spontaneous ovarian stimulation," "pregnancy," and "hypothyroidism" revealed only five cases: three associated with pregnancies and two with primary hypothyroidism. CASE: A 25-year-old white gravida 2, para 1, at 11-12 weeks' gestation presented with mild distension of a nontender abdomen, myxedematous facies, and large bilateral, multilobulated ovarian cysts. Conception had occurred spontaneously. Thyroid stimulating hormone was elevated, and free triiodothyronine and free thyroxine were low. Hypothyroidism, associated with spontaneous ovarian hyperstimulation syndrome, was diagnosed, and oral levothyroxine (0.10 mg/day) was started. With TSH still elevated at 21 weeks, levothyroxine was increased to 0.20 mg/day, and by 24 weeks, TSH and ovarian size were normal. Vaginal delivery of a 1120 g male infant occurred at 28 weeks. CONCLUSION: A case of naturally conceived pregnancy associated with spontaneous ovarian hyperstimulation and primary hypothyroidism is reported.

Adult↗
PubMed1999

Bartter's syndrome and pregnancy.

Bartter's syndrome is a rare renal tubular disorder and few cases are reported associated with pregnancy. We describe a case of long standing disease with a good obstetric outcome in which the main concern was to maintain normal potassium serum levels.

Adult↗
PubMed1998

Alpha3beta1-integrin as a critical mediator of the hepatic differentiation response to the extracellular matrix.

The extracellular matrix (ECM) promotes the differentiation of many cell types, and ECM remodeling in the liver has been implicated in embryonic development, tissue injury, and oncogenesis. Integrins are heterodimeric ECM receptors that play critical roles in transducing the composition of the ECM in the cell environment. We previously showed that mouse H2.35 cells, a conditionally transformed, liver-derived cell line, assume a more differentiated hepatocyte morphology and enhanced liver-specific gene expression when the cells are cultured on gelatinous ECM substrata. Here we show that H2. 35 cells express relatively high levels of alpha3beta1-integrins, similar to that previously shown for immature hepatocytes, transformed hepatocytes, and biliary cells. However, the cell morphological responses that depend on alpha3beta1-integrin have not been defined. We found that transfecting H2.35 cells with antisense RNA construct directed to alpha3-subunit messenger RNA perturbs the initial cell attachment to laminin and collagen, and strongly inhibits cell morphological, proliferative, and gene expression responses to a collagen gel substratum. In situ hybridization to mouse embryo tissues demonstrates the presence of alpha3-subunit messenger RNAs in newly formed hepatocytes. We suggest that alpha3beta1-integrins are important for immature and transformed hepatocytes to respond morphologically to the extracellular matrix.

Animals↗
PubMed1998

Cardiac consequences of renal transplantation changes in left ventricular morphology.

OBJECTIVE: The aim of this study was to characterize changes in left ventricular morphology and function by conventional echocardiography in a pediatric population after renal transplantation (RT). MATERIAL AND METHODS: This study includes 21 children, 11 female and 10 male, aged 11.8 +/-2.6 years at the time of renal transplantation. Eleven were on regular hemodialysis treatment and two on continuous peritoneal dialysis for 31.8 +/- 31.6 months; eight were transplanted without prior dialysis. Eight children were hypertensive before RT and nine (seven de novo) after RT. The patients were analysed in a prospective follow-up study with echocardiography immediately before and 30.2 +/- 15 months after successful renal transplantation. We measured the following echocardiographic parameters: Left ventricular end diastolic (LVED) and end systolic diameter (LVES), left atrial dimension (LAD), septal thickness (IVST), posterior wall thickness (PWT), shortening fraction (SF) and left ventricular index mass (LVIM). The paired Student's test, Fisher exact test and Pearson's correlation were used for statistical analysis. We analyzed the echocardiographic changes in the total group and separately in the subgroups with and without prior hemodialysis, as well as the influence of the duration of dialysis, anemia and hypertension. RESULTS: 1. After renal transplantation we found a decrease in the LVED LVES, LAD, IVST and PWT measurements (p < 0.05). There was a negligible increase in SF. The LVIM decreased from 139 g/m2 to 104 g/m2, representing a 21% reduction of the initial value, but this reduction was not of statistically significant. 2. The findings were similar in the hemodialysis group-LVIM decreased from 167.6 g/m2 to 94.9 g/m2, representing a 35% reduction in the initial value. 3. In the non dialysis group LVED, LVES, LAD and SVT decreased and LVIM showed a minor increase. There was a negligible increase in SF. 4. We found an increased LVIM in children with prior hemodialysis before RT, especially if dialysis lasted for more than two years. 5. Amelioration of hematocrit correlated with reduction of LVIM. 6. Regression of LV hypertrophy after RT was not dependent on blood pressure levels. CONCLUSIONS: Renal transplantation resulted in a tendency towards normalization of the echocardiographic parameters analysed: Contractility, as assessed by shortening fraction, was normal in this population. Although cardiac hypertrophy and dilation is reversible after RT, it would seem that children may benefit from an earlier transplantation.

Adolescent↗
PubMed1997

[Gaucher's disease in pregnancy].

A case of Gaucher's disease associated with pregnancy is reported. Although clinical symptoms were not present, portal hypertension was detected by ultrasound in the 13th week of pregnancy. Maternal anemia implied the use of erythropoietin from the 33rd week onwards. Good perinatal and maternal outcomes were achieved and there were no hemorrhagic complications.

Adult↗
PubMed1995

Major histocompatibility complex binding affinity of an antigenic determinant is crucial for the differential secretion of interleukin 4/5 or interferon gamma by T cells.

Differential activation of CD4+ T-cell precursors in vivo leads to the development of effectors with unique patterns of lymphokine secretion. To investigate whether the differential pattern of lymphokine secretion is influenced by factors associated with either the display and/or recognition of the ligand, we have used a set of ligands with various class II binding affinities but unchanged T-cell specificity. The ligand that exhibited approximately 10,000-fold higher binding to I-Au considerably increased the frequency of interferon gamma-producing but not interleukin (IL) 4- or IL-5-secreting cells in vivo. Using an established ligand-specific, CD4+ T-cell clone secreting only IL-4, we also demonstrated that stimulation with the highest affinity ligand resulted in interferon gamma production in vitro. In contrast, ligands that demonstrated relatively lower class II binding induced only IL-4 secretion. These data suggest that the major histocompatibility complex binding affinity of antigenic determinants, leading to differential interactions at the T cell-antigen-presenting cell interface, can be crucial for the differential development of cytokine patterns in T cells.

Amino Acid Sequence↗
PubMed1994

Development of 124 sequence-tagged sites and cytogenetic localization of 217 cosmids for human chromosome 10.

A total of 124 new chromosome 10-specific sequence-tagged sites (STSs) were derived from two sources: (1) DNA sequences obtained from anonymous clones in new libraries enriched for human chromosome 10 inserts, and (2) published sequences of genes and other loci already known to map to chromosome 10. Libraries were constructed from a somatic cell hybrid carrying human chromosomes 10 and Y. A cosmid library was made from total DNA of the hybrid and probed with labeled total human DNA to identify clones with human DNA inserts. Two hundred seventeen cosmids were mapped to regions of human chromosome 10 by fluorescence in situ hybridization. Twenty-five cosmids represent probes that have been placed on the genetic map previously. One hundred ninety-two cosmids represent new probes that have not been mapped previously. Cosmids carrying inserts with CA repeats were identified by hybridization with a labeled poly(dC-dA)-poly(dG-dT) probe and subcloned to yield microsatellite STS markers. Two small insert plasmid libraries were made, the first by subcloning inserts from a chromosome 10-enriched lambda phage library (LL10NS01) and the second by cloning Alu element-mediated PCR products amplified from hybrid DNA. STSs were generated from the DNA sequences of clone inserts. Chromosome 10-specific STSs were distinguished from Y chromosome STSs by one or both of the following criteria: (1) successful PCR amplification from a template consisting of DNA from another chromosome 10-containing cell line, NA10926B, or (2) FISH localization to chromosome 10 of the source cosmid or of YACs isolated by PCR screening with the STS. These libraries were the source of 90 new chromosome 10-specific STSs, 42 of which contain CA repeats.

Base Sequence↗
PubMed1994

Phorbol regulation of topoisomerases I and II in human leukemia cells. Studies in an additional cell pair sensitive or resistant to phorbol-induced differentiation.

We previously reported (Zwelling et al., Cancer Res 50: 7116-7122, 1990) that etoposide-induced DNA cleavage and mRNA coding for topoisomerase II are reduced in HL-60 cells induced to differentiate by phorbol ester. Reduction of etoposide-induced cleavage and topoisomerase II message did not occur in the derived cell line 1E3 (which is resistant to phorbol-induced differentiation), implying that topoisomerase II activity may be related to the state of cell differentiation. We have extended these studies using a new phorbol sensitive/resistant cell pair, S (sensitive) and PET (phorbol ester tolerant). Phorbol ester exposure not only reduced etoposide-induced DNA cleavage and topoisomerase II mRNA in S cells but also decreased the amount of immunoreactive topoisomerase II enzyme in whole S cells. However, immunoreactive topoisomerase II extracted from the nuclei of phorbol-treated S cells was not reduced compared with that from the nuclei of untreated S cells. This suggests that topoisomerase II contained in nuclear extracts is not always representative of the total cellular enzyme. Dramatic decreases in the amount, activity, or gene expression of topoisomerase II were not observed after phorbol treatment of the resistant PET cells; this is consistent with the potential involvement of topoisomerase II in monocytoid differentiation. Levels of topoisomerase I enzyme and mRNA fell in both S and PET cells after phorbol treatment; therefore, the genes for topoisomerases I and II did not appear to be regulated coordinately.

Cell Differentiation↗
PubMed1993

Further characterization of an amsacrine-resistant line of HL-60 human leukemia cells and its topoisomerase II. Effects of ATP concentration, anion concentration, and the three-dimensional structure of the DNA target.

The characterization of type II topoisomerases from amsacrine-sensitive (HL-60) and amsacrine-resistant (HL-60/AMSA) human leukemia cells was extended. The intercalator resistance and etoposide sensitivity of the HL-60/AMSA cells themselves were confirmed, and the stability of this pharmacologic phenotype over many hundreds of cell generations was demonstrated. Prolonging exposure of HL-60/AMSA cells to amsacrine did not alter their sensitivity relative to that of HL-60 cells. Improved methods of immunoblotting allowed clear demonstration that the topoisomerase II within these cells exhibited sensitivity and resistance characteristics that mirrored those of the cells and the isolated enzymes themselves. Additional biochemical characterization of the type II topoisomerases indicated that both enzymes relaxed supercoiled DNA in a distributive fashion and that the ATP concentrations at which optimal catalytic activity of the two enzymes was exhibited were identical. The enzymes differed, however, in their activity optima in buffers of various type and ionic strength. Furthermore, the inability of the HL-60/AMSA enzyme to exhibit enhanced DNA cleavage in the presence of amsacrine could be overcome if the DNA target molecule contained a bend cloned into its polylinker region. By contrast, a bend in a DNA plasmid containing no polylinker was resistant to amsacrine-enhanced cleavage in the presence of HL-60/AMSA topoisomerase II, as was a plasmid containing a polylinker with no bend. This suggests that an unusual DNA conformation (a bend) in a specific DNA context (a polylinker) may be a favored site for topoisomerase II action. It also suggests a mechanism by which the sites and extent of topoisomerase II activity can be controlled in cells.

Adenosine Triphosphate↗
PubMedDate not supplied

Atrial flutter ablation with a new radiofrequency catheter.

OBJECTIVE: To assess the performance of a new radiofrequency catheter, specially designed for inferior vena cava-tricuspid annulus (IVC-TA) isthmus ablation, in the treatment of atrial flutter. PATIENTS: IVC-TA isthmus ablation was performed in thirteen patients, eleven men and two women, aged 60 +/- 12, with a diagnosis of typical atrial flutter, symptomatic despite anti-arrhythmic therapy. The flutter was present for more than one year in seven patients and was paroxysmal in the remainder. The echocardiogram showed atrial enlargement in six patients. Atrial flutter was an isolated phenomenon in seven patients and in the remainder was associated with arterial hypertension (two patients), ischemic heart disease (two patients) and dilated cardiomyopathy (two patients). METHODS: In the electrophysiologic study four diagnostic catheters were used, including one duodecapolar for mapping the tricuspid annulus. In the patients who presented with sinus rhythm, atrial flutter was induced with programmed atrial stimulation, and then the atrial activation circuit was mapped. To demonstrate the entrainment phenomenon the IVC-TA isthmus was over-stimulated, to prove that this was the slow zone of the circuit. The radiofrequency energy was applied in the IVC-TA isthmus with the Medtronic Cosio-Fluttr ablation catheter, for 60 sec per application, with temperature control and with a maximum energy output of 50 W. Criteria for success were not only the disappearance of the atrial flutter during the application of radiofrequency energy, but also the demonstration of bi-directional IVC-TA isthmus block. RESULTS: The primary success rate was 100%. The mean procedure time was 110 +/- 22 min, mean fluoroscopy time was 23 +/- 4 min and the number of radiofrequency energy pulses was 9 +/- 3. There were no complications. The patients were followed for a mean time of 8 +/- 4 months and atrial flutter recurred in only one patient (8%). CONCLUSIONS: Atrial flutter ablation with the new Medtronic Cosio-Fluttr catheter, specially designed for the application of radiofrequency at the IVC-TA isthmus, is a safe procedure and has a high success rate. It simplifies ablation, decreasing the number of radiofrequency energy pulses, without using long sheaths and keeping short procedure and fluoroscopy times.

Adult↗