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R Acevedo

Publications and source records attributed to R Acevedo.

11 recordsLinked to original sources
PubMed2004

Genome remodelling in three modern S. officinarumxS. spontaneum sugarcane cultivars.

This study provides evidence that nuclear and chromosome remodelling has taken place in sugarcane, a vegetative crop with a complex genome derived from interspecific hybridizations between Saccharum officinarum and S. spontaneum. Detailed knowledge on the chromosomal compositions of the three clones analysed was acquired. (1) All hybrid cultivars were found to be aneuploid, affecting both parental genomes (having chromosomes in addition to full genomes), with chromosome numbers from 2n=102-106 in My5514 and up to 2n=113-117 in C236-51. (2) Comparative in situ hybridization showed that about 16% of these chromosomes are inherited from S. spontaneum and less than 5% are recombinant or translocated chromosomes containing sequences of both S. officinarum and S. spontaneum. (3) Differences between the observed DNA contents (estimated by flow cytometry) and those expected from the number of chromosomes, allowed the introgression of additional S. spontaneum or S. officinarum DNA pieces into the B42231 and C236-51 cultivars to be estimated. (4) Size heterogeneity between S. officinarum homologous chromosomes carrying the 18S-5.8S-25S and 5S ribosomal genes (identified by FISH with pTa71 and pTa794, respectively) confirms remodelling occurred by chromosomal interchange events, at least in these homologous chromosomes. (5) Simultaneous visualization of nucleoli and NORs showed that all 18S-5.8S-25S loci were potentially functional in the three clones, independent of their origin and size.

Chromosome Mapping↗
PubMed2002

Behaviour of ribosomal genes and nucleolar domains during activation in sugarcane (Saccharum officinarum L.) root primordia: from the unsoaked quiescent state to the steady state of proliferation.

Changes in the organisation of ribosomal genes and nucleolar protein components were analysed in sugarcane (Saccharum officinarum L. cv Cristalina) from the time the quiescent primordia of the radical bands of nodes were stimulated to proliferate by water imbibition, until the meristematic population reached the steady state of proliferation in the growing roots. The kinetics of proliferation was evaluated by flow cytometry, and by the mitotic indexes, in roots of different lengths. All the quiescent cells were in a pre-replicative state (G0), with a 2C DNA content. During their activation process, they progressively reached the steady state of proliferation (mitotic index 7%), with rather fixed frequencies for cells with 2C (G1), 4C (G2), and values between them corresponding to cells replicating their DNA. Decondensation of the ribosomal genes was followed by FISH with probes for the major 25S and 18S rRNAs, and variations in the numbers of nucleoli were recorded in squashed cells after silver staining. The ultrastructure of nucleoli was analysed by electron microscopy, using the EDTA regressive staining for ribonucleoproteins. Quiescent nucleoli showed a clear segregation of their main components: Fibrillar Centre, Dense Fibrillar Component and Cajal's bodies while lacked any Granular Component. However the proliferating ones showed them highly intermingled, except for the Cajal's bodies. Our results revealed a high plasticity of the nucleolar domains in response to cell activation, and allowed to establish a correlation between dispersion of NORs with formation of small fibrillar centers and a nucleolus with all its domains intermingled, and the activation of cell proliferation during root sprouting.

Cell Cycle↗
PubMed2001

Orphanin-FQ/nociceptin inhibits kindling epileptogenesis and enhances hippocampal feed-forward inhibition.

The role of Orphanin-FQ/nociceptin in synaptic plasticity was assessed by its potency in modulating kindling epileptogenesis in vivo, and feed-forward inhibition in hippocampal recordings in vitro. In addition, a specific rabbit antiserum against this peptide was obtained and the immunohistochemical distribution of nociceptin was determined in rat brain slices. After the establishment of kindling epilepsy, by daily electrical stimulation of the piriform cortex, the i.c.v. injection of nociceptin, 20 min before the kindling stimulation, was not able to block the generation of the generalized seizures, nor to alter their duration. However, the i.c.v. injection of nociceptin, 20 min before each stimulation along the kindling process, depressed its development in a dose-dependent manner. This effect was specific since the nociceptin antagonist [Phe1psi(CH2-NH)Gly2]NC(1-13)NH2, but not the broad-spectrum opiate antagonist, naloxone, was able to completely block nociceptin actions. The inhibitory role of nociceptin was assessed by in vitro recordings from entorhinal cortex-hippocampal slices. By single pulses applied over the Schaffer collaterals, we found that synaptic transmission was facilitated onto CA1, but using a paired-pulse protocol, we found that nociceptin potentiated feed-forward inhibition. The immunohistochemical data show that nociceptin is expressed in limbic cortical regions, including the piriform cortex and the hippocampus. Our results demonstrate that nociceptin exerts a modulatory role in limbic excitability and suggest that it provides an inhibitory control in the development of epilepsy by possibly inhibiting the spread of excitation through the system, by favoring feed-forward inhibition.

Animals↗
PubMed2001

Dormancy and proliferation in Saccharum officinarumxS. spontaneum hybrids which differ in the number of the introgressed S. spontaneum chromosomes.

Proliferating cells remain transiently blocked at different cycle compartments until specific stressors are removed or until the cells become adapted to their presence. This paper investigates the efficiency of cycle blocks in three sugarcane hybrids with the full noble cane (Saccharum officinarum) genome (2n=8x=80) but differing in the number of introgressed S. spontaneum (2n=8x=64) chromosomes. The My5514, B42231 and C236-51 cultivars possess 20, 30 and 40 additional S. spontaneum chromosomes, respectively. Flow cytometry showed that over 90% of cells were accumulated with a 2C DNA content in their dormant primordia. The presence of S. spontaneum chromosomes decreased the low stringency of the 4C block. The greater the number of these chromosomes, the lower was the number of quiescent cells with a 4C DNA content (P<0.05). Shortly after stimulation of the primordia (85% relative humidity and 30 degrees C), i.e. in the 2 mm long roots, a negative correlation was found between the number of introgressed S. spontaneum chromosomes and the frequency of cells undergoing replication and mitosis. On the other hand, when roots were already proliferating under steady-state conditions (15 mm long roots) the more S. spontaneum chromosomes the cells possessed, the longer the relative time it took for all chromosomes to replicate and segregate, and the longer the relative time they spent in G(2), with the 4C DNA content. The presence of S. spontaneum chromosomes seems to be recognized by these proliferating cells as a stressor which preferentially activates checkpoint pathways operating at the second half of the cycle, but not at its onset.

Cell Cycle↗
PubMed1994

Diagnosis and treatment of primary hyperaldosteronism.

OBJECTIVE: To characterize the clinical and laboratory features of primary aldosteronism and to evaluate which diagnostic tests can discriminate surgically curable forms of this syndrome. DESIGN: Retrospective analysis of the following data from 82 patients with primary aldosteronism: blood pressure, serum electrolytes, urinary aldosterone and electrolytes, computed tomographic scans, plasma renin and aldosterone before and during upright posture, atrial natriuretic peptide, and adrenal vein aldosterone and cortisol. Clinical outcomes assessed after treatment included blood pressure, serum electrolytes, and plasma renin activity. RESULTS: Drug therapy was discontinued before diagnostic tests were done in 56 of 82 patients (34 with adenomas and 22 with hyperplasia). Compared with patients with hyperplasia, those with adenomas had higher systolic (184 mm Hg and 161 mm Hg, respectively; P < 0.001) and diastolic blood pressures (112 mm Hg and 105 mm Hg; P = 0.03), lower serum potassium levels (3.0 mmol/L and 3.5 mmol/L; P < 0.001), and higher serum CO2 (P = 0.001), atrial natriuretic peptide (P = 0.008), and urinary 18-methyl oxygenated cortisol metabolite levels (P = 0.02). In patients with adenomas, aldosterone secretion lateralized to one adrenal gland and did not increase during the postural stimulation test; preoperative urinary aldosterone levels were correlated with diastolic pressures (r = 0.58; P = 0.001). Hypertension was "cured" postoperatively in approximately 35% of patients with adenomas and those with hyperplasia (P > 0.2) but was "improved" more frequently in those with adenomas (P = 0.002). Cured patients from both groups were younger than those not cured (mean ages, 43 years and 54 years, respectively; P = 0.002) and had lower preoperative mean plasma renin activity (0.17 ng/mL per hour and 0.50 ng/mL per hour; P < 0.001). All patients with adenomas in whom aldosterone secretion lateralized were either cured or improved. CONCLUSION: Of the 51 patients with primary aldosteronism who had adrenalectomy (43 patients with adenomas and 8 with hyperplasia), those most likely to be cured were younger and had lower plasma renin activity. In patients with adenomas who were cured or improved, aldosterone secretion was more likely to lateralize. Tests that distinguished adenomas from adrenal hyperplasia included the postural stimulation test, urinary excretion rates of 18-oxocortisol and 18-hydroxycortisol, and adrenal vein sampling.

Adenoma↗
PubMed1992

Hepatitis C virus is detected in a monocyte/macrophage subpopulation of peripheral blood mononuclear cells of infected patients.

Hepatitis C virus (HCV) is the primary agent of posttransfusion non-A, non-B hepatitis. HCV RNA was detected in peripheral blood mononuclear cells (PBMC) by polymerase chain reaction in 17 of 24 HCV-infected patients with chronic hepatitis with or without cirrhosis. One of 5 patients whose PBMC contained HCV RNA also had negative-stranded HCV RNA in the PBMC. In 3 of 11 patients whose PBMC contained HCV RNA, flow cytometry with a murine monoclonal antibody to HCV core epitope revealed cytoplasmic staining of peripheral blood monocytes. The monocyte surface and the peripheral blood lymphocytes did not stain for HCV core epitopes. No correlation could be made between the presence of HCV RNA or antigen in PBMC and any serologic markers of HCV infection. These results indicate that monocyte uptake of HCV by either phagocytosis or infection may be part of the pathophysiology of this chronic disease.

Adult↗
PubMed1991

Acquired immune dysfunction in cats with experimentally induced feline immunodeficiency virus infection: comparison of short-term and long-term infections.

Specific pathogen-free domestic cats with experimentally induced feline immunodeficiency virus (FIV) infections of short duration (less than or equal to 10 months) exhibited depressed total leukocyte and neutrophil numbers and a marginally decreased lymphocyte proliferative response to pokeweed mitogen (PWM), while cats with infections of more lengthy duration (greater than or equal to 25 months) exhibited normal leukocyte and neutrophil numbers but a dramatic loss of responsiveness to both PWM and concanavalin A (Con A). Cats with short-term infections exhibited a decrease in the percentage of CD4+ lymphocytes in peripheral blood and a corresponding depression of the CD4+:CD8+ ratio. Cats with long-term infections exhibited a similar but more profound perturbation of the CD4+ lymphocyte subset that also included a decrease in the absolute number of CD4+ cells. The decreased responsiveness to Con A and PWM in cats infected long term paralleled the decline in CD4+ cell counts, and the duration of infection was directly correlated with the decrease in the percentage of CD4+ cells. These data provide evidence supporting the hypothesis that FIV is the cause of an immune dysfunction in cats, with distinct similarities to that produced by human immunodeficiency virus (HIV) in people.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

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Dentistry↗