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Biomedical subjects

Christine A Johnson

Publications and source records attributed to Christine A Johnson.

9 recordsLinked to original sources
PubMed2006

Recruitment of healthy participants for studies on risks for alcoholism: effectiveness of random digit dialling.

AIMS: To compare the effectiveness of two strategies for recruiting healthy research volunteers. METHODS: Demographic characteristics and recruitment costs of participants who completed a laboratory study examining risk factors for alcoholism recruited through random digit dialling (N = 11) and community advertisements (N = 102) were compared. RESULTS: Advertisement yielded a more representative sample [76% Caucasian, less well educated (M = 15.2 years, SEM = 0.2; P < 0.05), more equally divided by family history of alcoholism (43% FH- and 57% FH+), and lower in SES (M = 42.8, SEM = 1.3; P < 0.05)] and was more cost effective (72 dollars vs 2272 dollars per participant) than random digit dialling. CONCLUSIONS: Findings are relevant to alcohol researchers trying to determine the recruitment strategy that will yield the most representative sample at the lowest cost.

Adolescent↗
PubMed2006

Premarital education, marital quality, and marital stability: findings from a large, random household survey.

One of the limitations of experimental studies on the effectiveness of premarital education is the reliance on samples of mostly White, middle-class couples. In contrast, although survey methods allow only weak inferences about causal relations, representative surveys can yield important information about use and estimated effects across a diverse population. Using a large random survey of 4 middle American states, the authors found that participation in premarital education was associated with higher levels of satisfaction and commitment in marriage and lower levels of conflict-and also reduced odds of divorce. These estimated effects were robust across race, income (including among the poor), and education levels, which suggests that participation in premarital education is generally beneficial for a wide range of couples.

Adult↗
PubMed2006

Impact of parasite sympatry on the geographic mosaic of coevolution.

Slave-making ants are specialized social parasites that steal the young from colonies of their host species to augment their slave supply. The degree of parasite-host specialization has been shown to shape the trajectory along which parasites and hosts coevolve and is a prime contributor to the geographic mosaic of coevolution. However, virtually nothing is known about extrinsic influences on parasite-host dynamics, although the simple addition of a competing slave-maker may significantly alter selection pressures. Here we report the effect of two sympatric slave-makers on a single host. We measured temporal and spatial changes in colonies of the primary host Temnothorax curvispinosus that had been placed in field enclosures along with a single colony of either one or both species of the North American slave-making ants Protomognathus americanus and Temnothorax duloticus. Each slave-maker species alone had a negative impact on its hosts, although one slave-maker species more frequently decimated its host assemblage and then went extinct. Nevertheless, the combined effect in mixed-parasite enclosures was, surprisingly, greatly attenuated. Virulent slave-maker growth and prudent slave-maker decay in these shared enclosures, together with field data showing an inverse proportional relationship between the two slave-makers in natural populations, suggest that their checkered distribution is a consequence of direct asymmetrical antagonism between parasites. Thus, our results imply a tripartite coevolutionary arms race, whereby intraguild interactions among social parasites strongly affect the realized selection pressures on hosts and contribute to the geographic mosaic of coevolution.

Animals↗
PubMed2005

A diabetes prevention assessment tool for American Indians.

INTRODUCTION: American Indians have a disproportionately higher risk of developing type 2 diabetes. Few data are available about the perceptions of diabetes among American Indians, and no culturally appropriate tools are available for assessment of perceptions related to health and diabetes. METHODS: A diabetes prevention assessment tool was developed to measure perceptions of health and diabetes among American Indians. Predominant themes from qualitative interviews were used to develop the items for the tool. Data were collected at two autumn powwows, or intertribal dances, in Oklahoma. Reliability testing was performed using 185 surveys from American Indian adults not living on reservations. Principal axis factor analysis was performed to identify possible relationships among the items. RESULTS: Five themes, or factors, were found to categorize the perceptions of health: 1) lifestyles, 2) barriers to healthy lifestyles, 3) personal responsibility, 4) self-care behaviors, and 5) culturally defined well-being. Two factors classified the perceptions of diabetes: 1) a cognitive factor, related to personal experience, and 2) an affective factor, related to emotions. CONCLUSION: Our diabetes assessment tool identified factors that should be considered when developing health promotion and diabetes prevention programs for American Indians. A valid assessment tool for the American Indian population could provide valuable, formative data that would increase understanding of the culturally related obstacles to health promotion and diabetes prevention.

Adolescent↗
PubMed2004

Patterns of continuing professional education in registered dietitians and dietetic technicians, registered.

This study compared the continuing professional education (CPE) activities of registered dietitians (RDs) with those of dietetic technicians, registered (DTRs). A descriptive research study was used with data from the baseline survey evaluating the Commission on Dietetic Registration's (CDR) Professional Development Portfolio. The survey was sent to 3,530 randomly selected RDs and DTRs; 1,429 surveys were returned (40.5% response rate), with 41% of RDs contacted responding and 32% of DTRs responding. Guidance used when selecting CPE activities and type of CPE activity selected were measured. DTRs sought more guidance than RDs when selecting CPE activities (P=.001). A significantly higher percentage of RDs than DTRs selected lectures, workshops, journal clubs, satellite courses, exhibits, professional leadership, professional reading, and poster sessions as CPE activities (P<.05). These findings will aid CPE providers in knowing which CPE activities are typically selected by both dietetics credential groups. DTRs may need guidance in selecting CPE activities.

Adult↗
PubMed2003

The emergence of collective foraging in the arboreal Gnamptogenys menadensis (Hymenoptera: Formicidae).

Gnamptogenys menadensis is an arboreal nester that forages opportunistically almost exclusively on vegetation, sometimes recruiting others to participate in prey retrieval. The three-dimensional characteristics of vegetation suggest that functions describing recruitment decision thresholds or the pattern of recruitment in arboreal species may differ from those predicted by optimal foraging theory. To examine the effects of prey abundance and distance on the recruitment dynamics of G. menadensis, we baited nests with one termite, five termites or a number of termites between 20 and 40 either near to or far from the entrance and observed the ensuing behaviors. G. menadensis recruited others when encountering multiple termites regardless of the termite pile's distance from the nest, although a few individuals remained at the site and defended the resource. The pattern of arrivals at the site indicates that the majority and sometimes all arrivals were recruited from the branch trails. In combination, these results suggest that the architecture of the foraging habitat, which limits available return routes to the nest and thus increases encounter probabilities with potential recruits, shaped the process of information transfer and generated a collective pattern of foraging and prey retrieval.

Animals↗
PubMed2002

Response of Diamond-Blackfan anemia to metoclopramide: evidence for a role for prolactin in erythropoiesis.

A 47-year-old woman with severe macrocytic anemia markedly improved during the second and third trimesters of 3 pregnancies and when breast-feeding her 2 children. Because the serum prolactin level is elevated at these times, we later treated her with metoclopramide (10 mg orally 3 times daily), a medication known to induce prolactin release. Her serum prolactin levels increased from 7 to 133 ng/mL (normal < 20 ng/mL) and hematocrit from 17% to 22% to 35%. With continued therapy (now 10 mg orally daily), her hematocrit has ranged from 30% to 40% for 6 years, although the macrocytosis persists (mean corpuscular volume, 100-112 fL). On the basis of this observation, a pilot study was undertaken of metoclopramide therapy in patients with Diamond-Blackfan anemia who were refractory to low doses of corticosteroids. Fifteen patients were enrolled and 9 completed the planned 16 weeks of therapy. Three individuals responded, suggesting that this therapeutic approach may benefit others. As with the index case, the anemia did not improve until 12 to 15 weeks of therapy had been completed.

Anemia, Diamond-Blackfan↗
PubMedDate not supplied

Interpretation of fetal hemoglobin only on newborn screening for hemoglobinopathy.

Newborn screening for hemoglobinopathies rarely produces a fetal hemoglobin only result; it is most consistent with beta-thalassemia major, although other diagnoses are possible. The authors describe two unrelated African-American babies born in North Carolina whose newborn screening revealed fetal hemoglobin only. Both had a relatively benign clinical and hematologic picture. Molecular analyses indicated that both children are compound heterozygotes for beta-thalassemia and pancellular (deletional) hereditary persistence of fetal hemoglobin, a rare and apparently benign condition. Accurate interpretation of the fetal hemoglobin only result on newborn screening requires thorough evaluation, including family studies and molecular analysis.

Black or African American↗