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At least 1,621 records · Page 90Linked to original sources
PubMed2004

Medical genetics in Zulia, a State of Venezuela.

Zulia is a state located in the northwest of Venezuela. Congenital malformations, deformities and chromosomal anomalies are the second cause of infant and neonatal mortality. There are seven public and private groups providing genetic services, the most important of which, the Medical Genetic Unit at the Zulia University was created in 1973. So far, this unit has provided genetic services to 12,000 families, and has been responsible for undergraduate and postgraduate education in human and medical genetics. Prenatal diagnosis is performed at the Unit and a private practice group, the most frequent referral reason being advanced maternal age. The most frequent genetic diseases in the state are Huntington's disease, sickle cell anemia, neural tube defects and Down's syndrome. Research in genetics includes the clinical, epidemiological and molecular characterization of hereditary diseases, cancer, reproductive problems and genetic diversity. Other public groups are conducting research on dementias, including Alzheimer's disease, and on the genotoxic effects of environmental pollutants.

Congenital Abnormalities↗
PubMed1995

Tinkering with the tinkerer: pollution versus evolution.

Pollutants can act as powerful selective forces by altering genetic variability, its intergenerational transfer, and the size, functional viability, adaptability, and survival of future generations. It is at the level of the cell and the individual that meiosis occurs, that genetic diversity is maintained, and behavior, reproduction, growth, and survival occur and are regulated. It is at this level that evolutionary processes occur and most pollutants exert their toxic effects. Chronic exposure to chemicals contributes to the cumulative stress on individuals and disrupts physiological processes and chemically mediated communication thereby threatening the diversity and long-term survival of sexually reproducing biota. Regional or global effects of pollution on the atmosphere, hydrosphere, and lithosphere have indirectly altered Earth's life-support systems, thereby modifying trace metal balance, reproduction, and incidence of UV-B-induced DNA damage in biota. By altering the competitive ability and survival of species, chemical pollutants potentially threaten evolutionary processes and the biodiversity and function of intercepting ecosystems.

Animals↗
PubMedDate not supplied

Non-consensual sterilization of the adult with learning disabilities.

Community nurses may be asked for advice on sterilization operations for adults with learning disabilities by worried parents/carers. This article sets out the legal position advocated by the English courts. Sterilization for adults with learning disabilities is generally non-consensual. The courts cannot consent on behalf of the adult but can rule on the lawfulness of the operation. Cases need not be brought before the court when the operation is to be carried out to treat a specific menstrual malady and where sterilization is an incidental result. However, the Law Commission (1995) has set guidelines which recommend that such operations require a certificate from an independent medical practitioner. In operations where the sole purpose is contraception the courts will always need to be involved. Their decision on the lawfulness of the operation will be based on what is in the person's best interests which in turn will be determined by reference to standards set by a responsible body of medical practitioners.

Adult↗
PubMed2005

Models of general frequency-dependent selection and mating-interaction effects and the analysis of selection patterns in Drosophila inversion polymorphisms.

We investigate mechanisms of balancing selection by extending two deterministic models of selection in a one-locus two-allele genetic system to allow for frequency-dependent fitnesses. Specifically we extend models of constant selection to allow for general frequency-dependent fitness functions for sex-dependent viabilities and multiplicative fertilities, while non-multiplicative mating-dependent components remain constant. We compute protected polymorphism conditions that take the form of harmonic means involving both the frequency- and the mating-dependent parameters. This allows for a direct comparison of the equilibrium properties of the frequency-dependent models with those of the constant models and for an analysis of equilibrium of the general model of constant fertility. We then apply the theory to analyze the maintenance of inversion polymorphisms in Drosophila subobscura and D. pseudoobscura, for which data on empirical fitness component estimates are available in the literature. Regression on fitness estimates obtained at different starting frequencies enables us to implement explicit fitness functions in the models and therefore to perform complete studies of equilibrium and stability for particular sets of data. The results point to frequency dependence of fitness components as the main mechanism responsible for the maintenance of the inversion polymorphisms considered, particularly in relation to heterosis, although we also discuss the contribution of other selection mechanisms.

Animals↗