PubMed Health⌕ Search

Biomedical subjects

M Godoy

Publications and source records attributed to M Godoy.

At least 19 recordsLinked to original sources
PubMed2000

Mixed-spin ising model with one- and two-spin competing dynamics

In this work we found the stationary states of a kinetic Ising model, with two different types of spins: sigma=1/2 and S=1. We divided the spins into two interpenetrating sublattices, and found the time evolution for the probability of the states of the system. We employed two transition rates which compete between themselves: one, associated with the Glauber process, which describes the relaxation of the system through one-spin flips; the other, related to the simultaneous flipping of pairs of neighboring spins, simulates an input of energy into the system. Using the dynamical pair approximation, we determined the equations of motion for the sublattice magnetizations, and also for the correlation function between first neighbors. We found the phase diagram for the stationary states of the model, and we showed that it exhibits two continuous transition lines: one line between the ferrimagnetic and paramagnetic phases, and the other between the paramagnetic and antiferrimagnetic phases.

Journal Article↗
PubMed1999

The tau gene A0 allele and progressive supranuclear palsy.

BACKGROUND: Recent studies have shown an association between a polymorphic tandem repeat allele, located in intron 9, of the tau gene and progressive supranuclear palsy (PSP). OBJECTIVE: To investigate this tau polymorphism in individuals with a clinical diagnosis of sporadic or familial PSP as well as in cases confirmed by pathology. METHODS: We analyzed the frequency of tau intronic polymorphism, the presence of linkage in two families with multiple cases of PSP, the splicing of exon 10, and direct sequence of the tau gene. RESULTS: We found that patients with a clinical diagnosis of sporadic or familial PSP and individuals with PSP confirmed by neuropathology have greater prevalence of the A0 allele and A0/A0 genotype than controls. This finding, however, was also true for asymptomatic relatives of individuals with PSP. Linkage analysis in familial PSP excluded the location of the gene in the region 17q21. Furthermore, no significant differences were found in the level of expression of exon 10 in PSP, A0/A0 brain with respect to Alzheimer A3/A3 brain. We found no mutations in the tau gene in individuals with familial PSP. CONCLUSIONS: A mutation in the tau gene was not the primary cause of familial PSP. The role of tau and the tau A0 allele in white PSP patients remains unknown, although it may represent a genetic risk factor for several neurodegenerative disorders.

Aged↗
PubMed1995

[Relationship of average level and variability of blood pressure with the geometry of the left ventricle in systemic hypertension].

PURPOSE: To study the relation between the average level and variability of blood pressure (VBP) obtained by ambulatory monitoring (AMBP) and the geometric pattern (GP) of the left ventricle (LV) obtained by echocardiography (ECHO) in patients with hypertension (Hy) METHODS: AMBP and ECHO were performed in 37 patients with Hy, divided into three groups: group A--11 women using antihypertensive therapy (AH); group B--15 men using AH and group C--7 male and 4 female without AH. The GP of LV was obtained by ECHO based on mass index (MI) and relative thickness of the wall (RTW). Mean systolic (MSBP) and diastolic (MDBP) were analyzed during daytime (DT) and nighttime (NT) periods. VBP was defined by mean standard deviation (SD) of mean pressures considered. RESULTS: In G-A, there was a significant association between the MI and both VBP and MSBP (r = 0.65 and p < 0.005, r = 0.61, and p < 0.005, respectively), and MSBP and VBP during the DP (r = 0.64 and p < 0.005, r = 0.75, and p < 0.005). In G-B, there was a relation between the LVRTW (r = 0.55 and p < 0.005), and MSBP during the DP (r = 0.65 and p < 0.005). In G-C, there was a significant association (p < 0.005) between the MI and the MDBP in the DP and with the MSBP in the NP (r valueS ranged from 0.51 to 0.66). There was also a significant relation (p < 0.005) between the LVRTW and the SD of all variables in both DP and NP (r ranged from 0.47 to 0.78 and mean diastolic in the wakeful period (r = 0.42 to 0.78) and MDBP in the DP (r = 0.42 and p < 0.05). CONCLUSION: Both the increase in VBP and the mean BP are involved in the changes of LVGP in Hy.

Adolescent↗
PubMed1992

Transdifferentiation of macrophages into fibroblasts as a result of Schistosoma mansoni infection.

The possibility of transdifferentiation of macrophages into fibroblasts which could be at the origin of fibrotic tissue in schistosome-infected mice was studied using immunocytochemical techniques. Macrophage cell samples extracted from the peritoneal cavity of schistosome-infected mice were fractionated on a Percoll gradient. The cultures were purified by treatment with a trypsin solution to eliminate any fibroblasts possibly collected along with the macrophages. Immunocytochemical methods were then used to characterize the cells at different points in time. The fibroblastic property of the morphologically transformed cells was confirmed by their positive labeling with the anti-procollagen antibody. However, these cells still possessed the mac-1 and mac-2 antigens which characterize the monomacrophage line.

Animals↗
PubMed1992

A study of peritoneal cells from healthy and Schistosoma mansoni-infected mice with special reference to myofibroblasts arising in culture.

Adherent, trypsin-resistant, peritoneal cells from mice with chronic schistosomiasis mansoni, and from control mice, were cultivated in vitro up to 20 days. Fibroblasts regularly appeared, about 6 days after seeding, in cultures of the manyfold more numerous cells from infected mice, concomitantly with a dramatic increase, detected by autoradiography, in the percentage of DNA-replicating cells of the monocyte-macrophage lineage. Peritoneal cells from healthy and from infected mice were fractionated on discontinuous Percoll gradients. Eight cell subsets were harvested in both cases, quantitated, and studied by electron microscopy. Two fractions (2 and 3: 1.041 < densities < 1.060 g/ml) from infected mice were greatly enriched in monoblasts and promonocytes. The cells of the different subsets were seeded separately, trypsin-treated and cultivated in vitro. Cultures of cell fractions 2 and 3 from infected mice contained the majority of the DNA-synthesizing cells and gave regularly rise to fibroblasts. Cultures of the different fractions were used for sequential morphological observations (2-11 days) at the electron microscope level. Early cultures were also used for the ultrastructural detection of the Mac-1 (CD 18/CD 11b) surface antigen by gold immunocytochemistry. A few fibroblasts were rarely observed in cultures of fractions 2 and 3 from control mice, while cells with ultrastructural features of myofibroblasts were regularly observed in cultures of the same fractions harvested from mice with chronic schistosomiasis. Fractions 2 and 3 from infected mice contained a large number of Mac-1 positive monoblasts. The correlations between the presence of monoblasts, DNA replication in cells of the monocyte-macrophage lineage and the appearance of myofibroblasts in cultures of the same fractions derived from infected mice are discussed.

Animals↗
PubMed1989

Schistosomiasis and in vitro transdifferentiation of murine peritoneal macrophages into fibroblastic cells.

We developed a method for avoiding contamination by fibroblasts when cultures of peritoneal cells are initiated. Macrophages were identified by immunogold detection [light microscope, transmission (TEM) and scanning (SEM) electron microscopes] of membrane antigens (Mac-1+, Thy-1,2-), non-specific esterase activity and ultrastructural features (TEM). As compared with controls, the yield of peritoneal macrophages was 2- and 12-fold higher, respectively, in acutely and chronically infected mice. In all, 30 "chronic", 18 "acute" and 18 control cultures were followed up. At a given cell-density seeding, the decline of control, "acute" and "chronic" cultures starts at about day 10, 15, and 27, respectively. In "chronic" cultures only, fibroblast-like cells appear from day 6 onwards; their number increases with time. Cells showing characters intermediary between macrophages and fibroblasts were observed. We suggest that fibroblast-like cells result from the in vitro transdifferentiation of a limited number of in vivo committed macrophages.

Animals↗
PubMed1984

Hemodynamic determinants of coronary constriction in human myocardial bridges.

To study the physiopathology of myocardial bridges, we assessed the degree of systolic coronary artery constriction (%SC) in different hemodynamic situations in six patients submitted for coronary angiograms. There was an increase of %SC (p less than 0.05) with sodium nitroprusside (NP), no modification during fast atrial stimulation (AS), and a decrease (p less than 0.05) during noradrenaline infusion (Nor). Hemodynamic studies indicate an inverse relation (p less than 0.05) between %SC and systolic and diastolic aortic pressure and left ventricular dP/dt. There was no correlation between changes in %SC and changes in Vmax or heart rate. Thus we conclude that changes in systemic arterial pressure and coronary perfusion pressure may significantly affect the degree of severity of myocardial bridges, possibly through an influence upon intraluminal coronary pressure and an intramyocardial tension relationship.

Adult↗