Showing papers by "Saint Anselm College published in 1997"

Signal‐induced Defensive Phenotypic Changes in Ciliated PProtists: Morphological and Ecological Implications for Predator and Prey1

Abstract: . Survival of a potential prey organism depends on the effectiveness of its physical, chemical, behavioral and life history responses to the appearance of a predator. Inducible defenses are flexible responses in which predator (or competitor)-released substances stimulate potential prey organisms to transform into predator-resistant phenotypes. Induced defenses may be highly protective. Benefits however are often balanced by fitness costs such as decreased growth rates or reduced reproductive potential. Here I discuss inducible defenses in ciliates with particular attention to the hypotrich genera: Aspidisca, Euplotes, Onychodromus, Sterkiella, and an undescribed hypotrich genus. I isolated Sterkiella sp. and the undescribed genus from vernal woodland pools on Saint Anselm College campus. Experimental evidence shows that a signal-induced defensive transformation occurs in these ciliates within hours after exposure to a predator cue and results in a significant decrease in susceptibility to predation. Deployment of ciliate antipredator structures such as spines, keels, ridges and other protuberances requires a large investment of cytoskeletal elements, primarily microtubules, and incurs an evolutionary cost in the form of significantly reduced growth rates. Onychodromus quadricornutus exhibits an extraordinary degree of phenotypic plasticity. In response to different environmental conditions individuals within a clone may express one of three general phenotypes: basic, lanceolate, or giant cells. The predacious giant phenotype releases a morphogenetically active signal substance, Onychodromus-factor, that triggers defensive phenotypic transformation in both intraspecific and interspecific prey. Enzyme degradation and ultrafiltration experiments indicate that Onychodromus-factor is a peptide with a molecular weight below 10,000 Da. Conspecifics develop hypertrophied dorsal spines when exposed to Onychodromus-factor. Sterkiella cells develop two defensive dorsal keels and transform to an enlarged ovoid cell in response to Onychodromus-factor as well as inducing signals released by Stylonychia, Urosyla, and Lembadion. Field studies of two vernal pools show that defensive phenotypic transformation in Sterkiella cells coincides with the appearance of Lembadion magnum during vernal pool succession. An undescribed hypotrich genus also expresses its defended phenotype when Lembadion is present in these pools. Aspidisca turrita (Ehrenberg, 1838) Claparede and Lachmann 1858, closely resembles Aspidisca lynceus (Muller, 1773) except for the possession of a dorsal thorn-like structure. Experimental evidence shows that the dorsal thron is a defensive structure induced by signals released by the predacious ciliates Urostyla grandis and Lembadion magnum. Thus, A. turrita and A. lynceus are alternate phenotypes of the same species. I speculate that inducing signals function in predacious ciliates as lectin-like, carbohydrate-binding adhesion proteins during prey recognition and that prey species have evolved specialized cell surface receptors that allow detection of different predator proteins. I consider consequences for both predator and prey.

The Breast Cancer Prevention Trial: Evaluating Tamoxifen’s Efficacy in Preventing Breast Cancer

Abstract: Objective: To review the literature on tamoxifen and breast cancer, focusing on the Breast Cancer Prevention Trial (BCPT). Data Sources: Computerized searches on MEDLINE and CINAHL. Study Selection: Articles from indexed journals in the English language related to the topics in this review and published after 1983 (except for earlier classic pieces) were evaluated. Data Extraction: Data were extracted and information was organized under the following headings: magnitude of the problem of breast cancer, definition of chemoprevention, tamoxifen's mode of action, risks and benefits, use as an adjuvant and in chemoprevention, the BCPT, study protocol, pros and cons, and nursing implications. Data Synthesis: The BCPT is a study testing tamoxifen's ability to prevent the development of breast cancer in healthy women at increased risk for developing the disease. About 16,000 women who are age 35years or older are being randomized to receive oral tamoxifen (20mg/day) or placebo for an initial period of 5years. Conclusions: The BCPT will contribute to our knowledge about tamoxifen's ability to prevent breast cancer in women at increased risk. Nurses have a role to play in implementing this strategy to find a means for preventing breast cancer.

Nursing management of second stage labor.

Abstract: Despite considerable research into nursing management of second stage labor, traditional approaches continue to predominate. Women are still encouraged to deliver in a recumbent position using sustained, closed-glottis pushing. Current research suggests that utilizing an upright position with pushing that is open glottis and complementary with the involuntary bearing-down reflex produces good maternal/fetal outcomes. Issues such as position, second stage phases, and bearing-down techniques are discussed in view of recent research findings. Gaps in knowledge are identified and practice implications are clearly defined. Now is the time to apply research-based knowledge to nursing management of second stage labor.

The Ethics of New Surveillance

Abstract: Communities and law enforcement personnel are confronted with the challenges and dangers posed by the presence of weapons and drugs. Recent technological developments have increased law enforcement capabilities to uncover previously hidden wrongdoing by using remote and, compared to other methods, unobtrusive search methods. This arti cle explores the capabilities of one new surveillance tool while consider ing the social, ethical, and legal implications of its use.

Cryptorchidism (undescended testes): A common congenital malformation associated with neurobehavioral abnormalities

Abstract: Cryptorchidism (undescended testes) is one of the most common congenital malformations in males. The National Collaborative Perinatal Project (NCPP) database yielded 50 bilateral and 93 unilateral cases of cryptorchidism matched to 286 controls for study center, socioeconomic status, birth order, and maternal age and education. At age 7 years, the incidence of frank mental retardation, borderline intelligence, and sensory deficits was significantly higher in males with bilateral cryptorchidism relative to their matched controls. When children with IQs > 85 were considered, those with unilateral cryptorchidism had significantly lower WISC Performance subscale scores relative to their matched controls. This was not an artifact of group differences in demographics, perinatal complications, physical growth, emotionality or motoric competence. Hence, cryptorchidism may be associated with maldevelopment of the brain.