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Biomedical subjects

A Rosa

Publications and source records attributed to A Rosa.

At least 19 recordsLinked to original sources
PubMed2007

Emerging role for microRNAs in acute promyelocytic leukemia.

Hematopoiesis is highly controlled by lineage-specific transcription factors that, by interacting with specific DNA sequences, directly activate or repress specific gene expression. These transcription factors have been found mutated or altered by chromosomal translocations associated with leukemias, indicating their role in the pathogenesis of these malignancies. The post-genomic era, however, has shown that transcription factors are not the only key regulators of gene expression. Epigenetic mechanisms such as DNA methylation, posttranslational modifications of histones, remodeling of nucleosomes, and expression of small regulatory RNAs all contribute to the regulation of gene expression and determination of cell and tissue specificity. Deregulation ofthese epigenetic mechanisms cooperates with genetic alterations to the establishment and progression of tumors. MicroRNAs (miRNAs) are negative regulators of the expression of genes involved in development, differentiation, proliferation, and apoptosis. Their expression appears to be tissue-specific and highly regulated according to the cell's developmental lineage and stage. Interestingly, miRNAs expressed in hematopoietic cells have been found mutated or altered by chromosomal translocations associated with leukemias. The expression levels of a specific miR-223 correlate with the differentiation fate of myeloid precursors. The activation of both pathways of transcriptional regulation by the myeloid lineage-specific transcription factor C/EBPalpha (CCAAT/enhancer-binding protein-alpha), and posttranscriptional regulation by miR-223 appears essential for granulocytic differentiation and clinical response of acute promyelocytic leukemia (APL) blasts to all-trans retinoic acid (ATRA). Together, this evidence underlies transcription factors, chromatin remodeling, and miRNAs as ultimate determinants for the correct organization of cell type-specific gene arrays and hematopoietic differentiation, therefore providing new targets for the diagnosis and treatment of leukemias.

CCAAT-Enhancer-Binding Protein-alpha↗
PubMed2005

Trichinellosis in Argentina: an historical review.

In Argentina, Trichinella infection in pigs is endemic. The first report of human trichinellosis in Argentina was from 1898 in Buenos Aires. The number of human cases increased from 908, between 1971 and 1981, to 6,919, between 1990 and 2002. In pigs slaughtered in official establishments, the prevalence of Trichinella infection was 0.46% in 1914 and 0.01--0.03% during the period 1990--2004. T. spiralis is typically found in the domestic cycle that includes pigs, humans and rodents. Trichinella spp. from a sylvatic cycle has also caused human outbreaks resulting from the consumption of meat from puma, armadillo and wild boar. European migration to Argentina (principally Spanish and Italian) during the first years of the 20th century brought the tradition of preparing and eating raw sausages. This increased the risk of human exposure to Trichinella. Detection in pigs was initially made at slaughter by compression of muscle tissue (trichinoscopy) and continued this way until 1996, when artificial digestion was adopted for use in preventing human trichinellosis in Argentina. The following report synopsizes the evolution of trichinellosis in Argentina over the past century.

Animals↗
PubMed2005

A new interpolation formula for semiflexible polymers.

A new formula for the force vs. extension relation is derived from the discrete version of the so-called Worm-like chain model. This formula correctly fits some recent experimental data on polymer stretching. Moreover, we have compared our formula with a Monte Carlo simulation of a semiflexible polymer.

Algorithms↗
PubMed2005

[Acetylcholinesterase inhibitor treatment for Alzheimer's disease: the experience in Picardy].

INTRODUCTION: Despite numerous advances in the management of patients with Alzheimer's disease (AD), the proportion of patients treated according to current recommendations remains unknown. METHODS: In order to examine this point, we performed a study assessing the proportion of AD patients receiving one acetylcholinesterase inhibitor. This study was performed in Picardy (1.9 millions of inhabitants) in 2000 and 2001. The number of patients receiving one acetylcholinesterase inhibitor (tacrine, donepezil, rivastigmine and galantamine) was determined using data from health insurance and from pharmaceutical companies. RESULTS: The prevalence of AD was estimated to vary from 10751 patients in 2000, to 10990 in 2001. The number of treated patients was 1798 in 2000 and 2572 in 2001 and this corresponded to 16.7 percent (95CI: 2.5) and 23.4 percent (95CI: 3.4) of prevalent cases, respectively. Following the exclusion of patients with moderate to severe AD (estimated to represent 25 percent of patients), the proportion of treated patients reached 22.4 percent (95CI: 2.3) in 2000 and 31.3 percent (95CI: 3.1) in 2001. CONCLUSIONS: Despite a significant increase between 2000 and 2001, this study shows that less than a third of AD patients with mild to moderate dementia were treated with acetylcholinesterase inhibitors. Although numerous factors might have affected our estimations, this study shows that effective care of AD patients remains largely insufficient.

Aged↗
PubMed2004

Toxocara canis in experimentally infected pigs: migratory pattern and tissue lesions.

Fifteen Yorkshire female pigs were inoculated with 100,000 infective T. canis eggs. Three animals were used as uninfected controls. Groups of three infected pigs were euthanized by accepted methods on days 7, 14, 21, 28 and 126 p.i., respectively. Larvae were recovered from all animals included in each group slaughtered on days 7 and 14 p.i.; on day 21 p.i. from two pigs, on day 28 p.i. from one, and no larvae were found on day 126 p.i. Differences in the mean number of larvae per gram in lymph nodes, liver and lungs between slaughter days, were significant for livers on day 7 p.i. and for lungs on day 14 p.i. (P < 0.10). The decrease over time was significant in all the organs that previously had larvae. Larvae were not found in the other organs and tissues analysed. Macroscopical lesions were found in the liver, lungs and lymph nodes on days 7, 14, 21, and 28 p.i. The entire surface of the liver was covered with small white spots on day 7 p.i., on days 14 and 21 p.i. the spots were distinctly nodular and, in some places, individual lesions were confluent. Lesions had apparently started to heal on days 28 and 126 p.i. appearance was normal. Lymph nodes were enlarged and oedematous during the first 4 weeks and the lungs had small areas of consolidation visible all over the surface, but by day 126 p.i., no visible lesions could be seen. Microscopical lesions were observed in the liver on day 7 p.i., with a largely periportal hepatitis. Numerous eosinophils and lymphocytes were present. The typical granulomatous reaction was observed on days 14 and 21 p.i. with a central necrotic core and a narrow region of fibroblastic tissue. By day 28 p.i. lesions had almost disappeared and the number of eosinophils was fewer. There were fewer leukocytes and the fibrous tissue had disappeared from the liver on day 126 p.i. For the first 3 weeks, pictures of the lymph nodes and the lungs were characterised by the formation of a granuloma. In the center of the granuloma larvae were observed. The majority of the lesions had healed by day 126 p.i.

Animals↗
PubMed2004

[Sarcoidosis revealed by a spinal cord lesion].

Spinal neurosarcoidosis is rarely a presenting symptom. This case deals with a 45-year-old african woman who presented with a regressive spinal cord compression treated by parenteral corticosteroid. Different relapses allowed to diagnose multiple sclerosis. Spinal MRI scan showed diffuse enlargement of the cord with intense intramedullary enhancement from C3 to T1 and an aspect of large spinal cord from C7 to D1. Cranial MRI scan was normal. Radiographs and CT scan of the chest revealed an interstital syndrome without mediastinal lymphadenopathy (subgroup III). The serum angiotensin converting enzyme level was elevated in the blood as the cerebrospinal fluid. CSF fluid showed a lymphocytic meningitis. The bronchio-alveolar lavage found an hyperlymphocytosis with a high CD4/CD8 ratio. The neurological status and biological parameters were improved with oral corticotherapy treatment. This case report that a spinal cord involvement can reveal a sarcoidosis especially in the African race. Finally, in spite of lack of biopsy, the diagnosis is supported by clinical, biological and neuroradiological arguments.

Female↗
PubMed2004

Stepwise unfolding of collapsed polymers.

Motivated by recent experimental data on DNA stretching in presence of polyvalent counterions, we study the force-induced unfolding of a homopolymer on and off lattice. In the fixed force ensemble the globule unravels via a series of steps due to surface effects which play an important role for finite-size chains. This holds both for flexible and stiff polymers. We discuss in a qualitative way how this result may impact on the interpretation of DNA stretching experiments showing peaks in the characteristic curves, by extracting from the raw data the corresponding elongation- versus-force characteristic curves. Furthermore, approximate analytical and numerical calculations, valid in a quasi-equilibrium fixed stretch ensemble, and if the initial low-temperature state is ordered in a spool, show that the average force versus elongation displays peaks related to the geometry of the initial configuration. We finally argue how the proposed mechanisms identified for the arising of peaks may couple in the experiments, and comment on the role of dynamic effects.

DNA↗
PubMed2003

Mechanical unfolding of directed polymers in a poor solvent: critical exponents.

We study the thermodynamics of an exactly solvable model of a self-interacting, partially directed self-avoiding walk in two dimensions when a force is applied on one end of the chain. The critical force for the unfolding is determined exactly, as a function of the temperature, below the Theta transition. The transition is of second order and is characterized by new critical exponents that are determined by a careful numerical analysis. The usual polymer critical index nu on the critical line, and another one which we call zeta, takes a nontrivial value that is numerically close to 2/3.

Journal Article↗
PubMed2003

Stretching of a polymer below the theta point.

The unfolding of a polymer below the theta point when pulled by an external force is studied both in d=2 on the lattice and in d=3 off the lattice. At T=0 and for finite length chains, it is found that the globule unfolds via multiple steps, corresponding to transitions between different minima, in both cases. In d=3 one of these intermediates is a regular helix. In the infinite length limit, these steps have a qualitative effect only in d=2. The phase diagram in d=2 is determined via the transfer matrix. To rationalize these results, energy-entropy and renormalization group arguments are given.

Biopolymers↗
PubMed2003

Ectopic pacing at physiological rate improves postanoxic recovery of the developing heart.

Recently, rapid and transient cardiac pacing was shown to induce preconditioning in animal models. Whether the electrical stimulation per se or the concomitant myocardial ischemia affords such a protection remains unknown. We tested the hypothesis that chronic pacing of a cardiac preparation maintained in a normoxic condition can induce protection. Hearts of 4-day-old chick embryos were electrically paced in ovo over a 12-h period using asynchronous and intermittent ventricular stimulation (5 min on-10 min off) at 110% of the intrinsic rate. Sham (n = 6) and paced hearts (n = 6) were then excised, mounted in vitro, and subjected successively to 30 min of normoxia (20% O(2)), 30 min of anoxia (0% O(2)), and 60 min of reoxygenation (20% O(2)). Electrocardiogram and atrial and ventricular contractions were simultaneously recorded throughout the experiment. Reoxygenation-induced chrono-, dromo-, and inotropic disturbances, incidence of arrhythmias, and changes in electromechanical delay (EMD) in atria and ventricle were systematically investigated in sham and paced hearts. Under normoxia, the isolated heart beat spontaneously and regularly, and all baseline functional parameters were similar in sham and paced groups (means +/- SD): heart rate (190 +/- 36 beats/min), P-R interval (104 +/- 25 ms), mechanical atrioventricular propagation (20 +/- 4 mm/s), ventricular shortening velocity (1.7 +/- 1 mm/s), atrial EMD (17 +/- 4 ms), and ventricular EMD (16 +/- 2 ms). Under anoxia, cardiac function progressively collapsed, and sinoatrial activity finally stopped after approximately 9 min in both groups. During reoxygenation, paced hearts showed 1) a lower incidence of arrhythmias than sham hearts, 2) an increased rate of recovery of ventricular contractility compared with sham hearts, and 3) a faster return of ventricular EMD to basal value than sham hearts. However, recovery of heart rate, atrioventricular conduction, and atrial EMD was not improved by pacing. Activity of all hearts was fully restored at the end of reoxygenation. These findings suggest that chronic electrical stimulation of the ventricle at a near-physiological rate selectively alters some cellular functions within the heart and constitutes a nonischemic means to increase myocardial tolerance to a subsequent hypoxia-reoxygenation.

Animals↗
PubMed2002

Prevalence of canine dirofilariosis in the City of Buenos Aires and its outskirts (Argentina).

During the past 10 years, the prevalence of canine dirofilariosis in the City of Buenos Aires and its outskirts, particularly in the northern and southern areas, has increased significantly. In the present work, studies were carried out in dogs living in the city and in its northern, western and southern outskirts from 1997 to 2001. For this purpose, 782 blood samples were collected and analyzed to determine circulating antigen, processed with the Witness Merial antigen test. The samples resulted in negative tests for subjects who lived in the city; however, 17.7 and 23.5% of the tests were positive from the northern and southern outskirts, respectively. When analyzed by sex, positive results were distributed as follows: 62.5% males and 37.5% females (P<0.05). No significant statistical difference was found on comparing purebred and cross-breds (P<0.05). It is interesting to point out the geographical distribution of the disease, which confirms that ecological factors such as water currents, abundant vegetation and the existence of mosquitoes all year round, are important for the biological cycle of Dirofilaria immitis.

Age Factors↗
PubMed2002

Arousal, EEG spectral power and pulse transit time in UARS and mild OSAS subjects.

OBJECTIVES: Upper airway resistance syndrome (UARS) and obstructive sleep apnea syndrome (OSAS) are associated with arousals and autonomic activation. Pulse transit time (PTT) has been used to recognize transient arousals. We examined the accuracy of PTT to recognize arousals, and the relationship between PTT deflection and visual and non-visual arousals. METHODS: Ten UARS and 10 mild OSAS subjects were studied via polysomnography including measurement of esophageal pressure. Electroencephalogram (EEG) spectral power was obtained from central leads. Seven types of events were identified, depending upon the presence or absence of: a sleep-related respiratory event (SRRE), i.e. apnea, hypopnea, and abnormal breathing effort; a PTT signal; or a visually scored arousal (>1.5s). RESULTS: One thousand four hundred forty-six events were identified in 20 subjects. Fifty-nine percent of all SRREs were associated with a PTT signal and a visual EEG arousal. Nineteen percent of SRREs had no EEG arousals at their termination, and 7.4% had no associated PTT signal. Delta power was significantly increased when non-visual EEG arousals were scored. The time delay for PTT was determined by the presence or absence of EEG arousal. The sensitivity of PTT to recognize EEG arousal was 90.4% and the specificity was 16.8%. The sensitivity and specificity of PTT to recognize SRRE was 90.7 and 21.9%, respectively. CONCLUSIONS: These results preclude the use of PTT by itself. SRREs induce an activation with positive PTT response but without arousal in 14% of cases. This PTT response, however, is much slower than that occurring with arousal. UARS and mild OSAS do not respond in the same way to SRREs, particularly during rapid eye movement sleep.

Adolescent↗
PubMed2001

The effect of ferric-nitrilotriacetic acid on the profile of polyunsaturated fatty acids in the kidney and liver of rats.

Intraperitoneal injection of the iron-complex, ferric-nitrilotriacetate (Fe-NTA), induces renal proximal tubular damage associated with oxidative damage in vivo. Fe-NTA induced a time-dependent decrease of several polyunsaturated fatty acids (PUFA), together with increased conjugated diene values and decreased cellular levels of alpha-tocopherol and glutathione. At the time of maximum detectable oxidation (3 h), after the injection of a sublethal dose of Fe-NTA there were clear reductions in the peak values over the controls for several fatty acids notably, 20:5 (eicosapentaenoic acid) (36%), 22:6 (docosahexanoic acid) (30%), 20:3 n6 (eicosatrienoic acid) (30%) and 20:4 (arachidonic acid) (28%) in the kidney. Fewer fatty acids showed a reduction in their residual values in the liver. 20:5 was reduced by 45% and for the 18:3 n3 and 18:3 n6, reductions of 35%, respectively. The profile of PUFAs is sensitive to the oxidative damage due to Fe-NTA and this may find applications as oxidative biomarker model.

Animals↗
PubMed2001

Association study between novel promoter variants at the 5-HT2C receptor gene and human patients with bipolar affective disorder.

Two recently described adjacent DNA polymorphisms [(GT)12-18 and (CT)4-5] in the 5'-regulatory region of 5-HT2C receptor gene were analysed in a sample of 88 bipolar patients and 162 controls, all of Spanish origin. Statistical analyses revealed no overall allele or genotype associations with the disease. A haplotype analyses between the (GT)12-18/(CT)4-5 motif and a Cys23Ser variant of the 5-HT2C gene (which had previously been genotyped in the same sample) showed similar distributions between cases and controls. Only a slight increase of s-Ser23 haplotype was found in the subgroup of bipolar women with family history of psychiatric illness (OR=1.24 [95%CI: 1.12-1.38]).

Bipolar Disorder↗
PubMed2001

Sporadic randomness: the transition from the stationary to the nonstationary condition.

We address the study of sporadic randomness by means of the Manneville map. We point out that the Manneville map is the generator of fluctuations yielding the Lévy processes, and that these processes are currently regarded by some authors as statistical manifestations of a nonextensive form of thermodynamics. For this reason we study the sensitivity to initial conditions with the help of a nonextensive form of the Lyapunov coefficient. The purpose of this research is twofold. The former is to assess whether a finite diffusion coefficient might emerge from the nonextensive approach. This property, at first sight, seems to be plausible in the nonstationary case, where conventional Kolmogorov-Sinai analysis predicts a vanishing Lyapunov coefficient. The latter purpose is to confirm or reject conjectures about the nonextensive nature of Lévy processes. We find that the adoption of a nonextensive approach does not serve any predictive purpose: It does not even signal a transition from a stationary to a nonstationary regime. These conclusions are reached by means of both numerical and analytical calculations that shed light on why the Lévy processes do not imply any need to depart from the adoption of traditional complexity measures.

Journal Article↗