Biomedical subjects

A Cuadrado

Publications and source records attributed to A Cuadrado.

58 records · Page 4Linked to original sources

PubMed1983

Partial elimination of G1 and G2 periods in higher plant cells by increasing the S period.

Meristematic cells from Allium cepa L roots can attain a steady-state of growth at both 15 and 25 degrees C in the presence of drugs, hydroxyurea and 5-amino-uracil, which reduce the rate of DNA synthesis. These drugs, at used concentrations, significantly lengthen the S period without altering the cell growth rate, as indicated by the maintenance of the generation time. It has been observed that steady-state populations respond to a gradual increase in S by a reduction of G2 until a minimum value; with larger lengthening of S, both G1 and G2 are reduced. Natural synchronous populations have been used to study cell cycle parameters during transition from the physiological steady-state to the new one created by the presence of the drug. G2 (but not G1) is reduced during transition even in the presence of maximum drug concentrations that do not alter the cell growth rate. Both the S period and the division time are lengthened during transition. These observations support the concept that certain fractions of G1 and G2 are expendable, because they have no role in the DNA-division sequence of cell cycle events. We conclude that cell size regulates the length of these fractions by means of a negative correlation.

Cell Cycle↗

PubMedDate not supplied

Evolutionary trends of different repetitive DNA sequences during speciation in the genus secale.

The presence and distribution of two simple sequence repeats (SSRs), three highly repetitive sequences from rye, and the 5S rDNA have been investigated in 3 rye cultivars and 10 wild-related species of the genus SECALE: The following conclusions can be drawn in addition to detailed knowledge of the sequence content of chromatin in each accession studied: (1) Every species is unique in either or both the complement and chromosomal distribution of the six repeated sequences analyzed. (2) These sequences reveal multiple landmarks along all the rye chromosomes arms. (3) High polymorphism as well as heterozygosity between homologues in the distribution of the (AAG)(5) and (AAC)(5) was revealed in the outbreeding species of the Secale strictum complex. (4) It is possible to deduce trends in the complexity of repetitive DNA during the evolution of the genus. A possible evolutionary pathway that accounts for the present-day Secale species is presented.

DNA, Plant↗

PubMedDate not supplied

[Advances in the physiopathology of epileptogenesis: molecular aspects].

OBJECTIVE: We review the molecular basis of epileptogenesis and the new perspectives in the treatment of epilepsy. DEVELOPMENT: Epileptogenesis are the molecular and cellular events producing the disordered firing of a subpopulation of neurons resulting in periodic seizures. Epilepsies may be due to genetic and acquired factors. Some idiopathic epilepsies are due to mutant genes coding voltage gated sodium and potassium channels, GABAA receptor chloride channels and nicotinic acetylcholine receptor sodium channels. Genetic defects also produce epilepsy secondary to either neuronal developmental or metabolic abnormalities, and may contribute to acquired epilepsy. Events observed in both animal and human acquired epilepsies are an increase in glutamate levels and NMDA receptor sensitivity, selective lost of pyramidal neurons, mossy fibre sprouting and neosinaptogenesis. There is also a reduction in inhibitory control due to lost of GABAergic interneurons, and a decrease in GABA levels and GABAA receptor sensitivity. Hyperexcitability may be also due to reduction in glial ATPasa activity, increase in astrocytes gap junctions, and decrease in extracellular calcium. Chandelier GABAergic interneuron microlesions and an hyperexcitable thalamus are key in spread of partial seizures. Absences may be caused by cortex hyperexcitability and genetic abnormalities in thalamic voltage gated T calcium channels. Brain stem is key in convulsive seizures. The role of voltage gated potassium, sodium and calcium channels, and GABAergic and glutamatergic neurotransmission in epileptogenesis and treatment of epilepsies are revised. The role of other neurotransmitters and neuromodulators, second messengers, and immediate early genes and neurotrophins are also commented. CONCLUSION: Understanding the molecular basis of epileptogenesis should lead to the rational design of drugs both to prevent the development of epilepsy, and minimize hyperexcitability which may be the result of a genetic or acquired disorder.

Animals↗

PubMedDate not supplied

[Diverticulum of the right ventricle with dilated myocardiopathy].

We report on a newborn infant with right ventricular diverticulum associated to dilated myocardiopathy, who was diagnosed by two-dimensional echocardiography within 24 hours after vaginal delivery. We believe this case represents the youngest one ever diagnosed with this disease.

Cardiomyopathy, Dilated↗