Biomedical subjects

E Strain

Publications and source records attributed to E Strain.

6 recordsLinked to original sources

PubMed2001

Characterization of mutations that feminize gametophytes of the fern Ceratopteris.

Gametophytes of the fern Ceratopteris are either male or hermaphroditic. Their sex is epigenetically determined by the pheromone antheridiogen, which is secreted by the hermaphrodite and induces male and represses female development in other young, sexually undetermined gametophytes. To understand how antheridiogen represses the development of female traits at the genetic level, 16 new mutations that feminize the gametophyte in the presence of antheridiogen were identified and characterized. Seven are very tightly linked to the FEM1 locus previously described. Nine others define another locus named NOTCHLESS1 (NOT1), as several of the not1 mutants lack a meristem notch. Some not1 mutations also affect sporophyte development only when homozygous, indicating that the not1 mutations are recessive and that NOT1 is also required for normal sporophyte development. The epistatic interactions among FEM1, NOT1, and other sex-determining genes are described. This information was used to expand the genetic model of the sex-determining pathway in Ceratopteris. On the basis of this model, we can say that the presence of antheridiogen leads to the activation of the FEM1 gene, which not only promotes the differentiation of male traits, but also represses female development by activating the NOT1 gene. NOT1 represses the TRA genes necessary for the development of female traits in the gametophyte.

Crosses, Genetic↗

PubMed1999

Imageability effects in word naming: an individual differences analysis.

The present research was designed to extend research by Strain, Patterson, and Seidenberg (1995) who found that imageability facilitates naming of low-frequency irregular words. Experiment 1 shows that the impact of imageability on word naming varies with phonological coding skill. In Experiment 2, the effect of imageability on naming low-frequency irregular words was shown to occur across an extended set of items. Together, the present findings support the notion that semantics may play a role in phonological coding when the mappings between orthography and phonology are weak.

Adult↗

PubMed1998

Word reading in Alzheimer's disease: cross-sectional and longitudinal analyses of response time and accuracy data.

Using a list of high- and low-frequency regular and exception words, we measured the reading performance of three groups of subjects: patients with mild dementia of the Alzheimer's type (DAT) at presentation (Stage 1) and 2-3 years later (Stage 2); moderately severe DAT patients; and control subjects. In the longitudinally studied patients, there was a dramatic increase in response times (RTs) from Stage 1 to Stage 2, but little change in either error rate or pattern. By contrast, a comparison of the Stage 2 with the Moderate patients revealed similar RTs but a significant increase in error rate for the Moderate group, particularly on low-frequency exception words. These two results for word naming were almost exactly mirrored by effects in picture naming. We conclude that correct word reading, especially for less common words with atypical spelling-sound correspondences, is compromised in DAT only when the disease produces a significant deterioration of semantic memory. These results are relevant to current theories about normal and impaired reading processes.

Aged↗

PubMed1995

Semantic effects in single-word naming.

Three experiments demonstrated that, for lower frequency words, reading aloud is affected not only by spelling-sound typicality but also by a semantic variable, imageability. Participants were slower and more error prone when naming exception words with abstract meanings (e.g., scarce) than when naming either abstract regular words (e.g., scribe) or imageable exception words (e.g., soot). It is proposed that semantic representations of words have the largest impact on translating orthography to phonology when this translation process is slow or noisy (i.e., for low-frequency exceptions) and that words with rich semantic representations (i.e., high-imageability words) are most likely to benefit from this interaction.

Adult↗

PubMed1990

Intravenous drug abusers with antisocial personality disorder: increased HIV risk behavior.

Intravenous drug abuse is strongly associated with HIV transmission and with having a diagnosis of Antisocial Personality Disorder (ASPD). While the co-occurrence of intravenous drug abuse and ASPD is related to poor drug abuse treatment outcome, little is known about the contribution of ASPD to the intravenous drug abusers (IVDAs) level of HIV risk. The present study related the diagnosis of ASPD with specific drug use behaviors associated with high risk of HIV transmission. Subjects (N = 100) were intravenous drug abusers who volunteered for an HIV risk assessment study. Subjects with ASPD reported significantly higher rates of injection-equipment sharing and shared with significantly more people than IVDAs without ASPD.

Adult↗

PubMed1990

The behavioral pharmacology of alcohol and other drugs. Emerging issues.

Alcohol and other drugs are compared with respect to their abuse liability and dependence potential. Drug-reinforced behavior is defined, and factors related to the establishment of this behavior that have received increasing experimental attention in recent years are reviewed. Acquisition techniques, schedule of access, route of self-administration, and organism factors, such as species, gender, and genetic background, are discussed. Other areas of emerging interest are the effect of feeding regimens, alternative reinforcers, and social conditions on drug-reinforced behavior. Also, biochemical factors such as neurochemical alterations, hormonal changes, and alcohol and other drug combinations, are considered. Finally, dependence potential is considered in terms of observational changes and performance alterations that seem to be sensitive indicators of the protracted aspects of drug withdrawal. The relationship between drug-seeking behavior and withdrawal is examined.

Alcohol Drinking↗