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Biomedical subjects

D Cross

Publications and source records attributed to D Cross.

At least 19 recordsLinked to original sources
PubMed1992

The right-hemisphere bias in conditional reasoning: a short report on multiple failures to replicate previous findings.

The present set of studies attempted to replicate Gellatly's (1985) findings that were supportive of Evan's (1982) hypothesis that the right hemisphere produces a selective bias towards the incorrect solution of a complex reasoning task. Subjects solved problems of the form "if p then q." In four studies, participants simultaneously performed a bottle--balancing task on each hand to interfere with processing of the reasoning task in the right hemisphere. In the fifth study, the bottle--balancing task was replaced by a finger--sequencing task. The results of the five studies did not show that the interference with right-hemisphere activity resulted in better performance on the conditional-reasoning task. It is concluded that the hypothesis of a right-hemisphere bias in conditional reasoning is still in need of reliable findings.

Attention↗
PubMed1992

An interpersonal-epistemological curriculum model for nurse education.

This paper proposes a curriculum model for nurse education which holds forms of knowledge and interpersonal relationships as key issues if nurse education is to develop autonomous, reflective, critical practitioners. By adopting areas of cognitive interest, principles of andragogy and the concept of reflection-in-action, the model provides a heuristic tool which attempts to enable the provision of a nurse education which is devoted to adult learning processes and relevant to the development of education in the practice setting. The technical, practical and emancipatory areas of cognitive interest provide an understanding of learning domains which require different knowledge bases, methods of learning and forms of assessment to each other. The pedagogy/andragogy dichotomy is presented to reflect two teaching paradigms. The former approach is derived from the activity of teaching children and provides for passive dependence. The latter is more appropriate to adult learning and student self-direction. The model attempts to promote the transitional dynamic which moves the student nurse toward a state of greater self-direction. Finally, the concept of reflection-in-action is discussed in an attempt to ensure that the areas of cognitive interest and the learning strategies are inextricably linked to the practice component of a professional nurse education. All three dimensions are combined to show how each should develop in unison as the professional education of the nurse proceeds along a chronological dimension.

Clinical Competence↗
PubMed1992

A three-year evaluation of the know your body program in inner-city schoolchildren.

The impact of the Know Your Body (KYB) comprehensive school health education program was evaluated in a sample of first through sixth-grade students from New York City, using two analytic strategies: a longitudinal cohort and a "posttest only" cohort. In both cohorts, program impact was examined between condition (i.e., KYB vs. no-treatment comparison group) as well as within condition (i.e., low, moderate, and high student exposure). Students in the longitudinal cohort (n = 1,209) who were exposed to high implementation teachers had significantly (p < .05) lower total plasma cholesterol and systolic blood pressure at 3-year posttest than comparison students. Students in the posttest only cohort (n = 3,066) who had high implementation teachers showed significantly (p < .05) lower total plasma cholesterol, systolic blood pressure, self-reported intake of meat and desserts, as well as higher health knowledge and self-reported intake of "heart healthy" foods and vegetables than comparison students. In both cohorts, program effects for several outcome variables were linearly related to level of student exposure to the curriculum, suggesting a dose-response effect. While several methodologic limitations may have influenced study outcomes, these data nonetheless appear to confirm that the KYB program can have a significant positive impact on the knowledge, behavior, and selected risk factors of students in primary grades and that efforts to disseminate and evaluate school health education programs should include strategies to monitor and enhance teacher implementation.

Blood Pressure↗
PubMed1991

Comparison of effects of thrombolytic therapy on left ventricular function in patients over with those under 60 years of age.

This study examined the effect of age on left ventricular (LV) function, assessed by contrast ventriculography 3 weeks after a first acute myocardial infarction in 312 patients who received thrombolytic therapy within 4 hours of the onset of infarction and in 83 patients who received placebo. Streptokinase was given to 188 patients and recombinant tissue-type plasminogen activator (rt-PA) to 124. Patients were divided into 2 age groups: less than 60 years (n = 244) and greater than or equal to 60 years (n = 151). Thrombolytic therapy improved ejection fraction in both age groups: from 54 +/- 13 to 59 +/- 11% (p = 0.021) in the younger group and from 50 +/- 14 to 57 +/- 13% (p = 0.004) in the older group. Ejection fraction was identical in streptokinase- and rt-PA-treated patients. Multifactor analysis of variance revealed that younger age and thrombolytic therapy were independently associated with improved ejection fraction. Thrombolytic therapy also reduced end-systolic volume (p = 0.001) by 14 ml in the elderly and 9 ml in the younger group. Minor bleeding complications were more frequent in the elderly and 3 serious hemorrhages occurred in patients greater than or equal to 60 years. These findings reveal that thrombolysis improves LV function in all age groups studied. Because increasing age is independently associated with a lower ejection fraction after acute myocardial infarction, thrombolytic therapy may confer greater benefits in older patients.

Age Factors↗
PubMed1991

MAP-1 and MAP-2 binding sites at the C-terminus of beta-tubulin. Studies with synthetic tubulin peptides.

The interaction of microtubule-associated proteins MAP-1 and MAP-2 with different peptides containing sequences covering the C-terminal region of beta-tubulin isoforms has been analyzed. Our results indicate that MAP-1 and MAP-2 bind to a common sequence within the variable C-terminal region of the different beta-tubulin isoforms, while MAP-2 also interacts with the subdomain beta (422-434) of the constant region, in agreement with previous results (Maccioni, R.B., Rivas, C., & Vera, J.C. (1988) EMBO J. 7, 1957-1963). The productive interaction of MAP-2 with the latter domain appears to be involved in the assembly of microtubules.

Amino Acid Sequence↗
PubMed1991

Teaching and assessing on course for change.

This paper argues that the concept of change is a valuable tool for the development of continuing education which is relevant to the personal needs of nurse practitioners and to clinical practice. The context for this discussion is a teaching and assessing course which holds the concept of change as the central philosophy for curriculum structure. The paper begins by describing the course philosophy, curriculum models and outline structure which typify this course. The second part of the paper describes research used to evaluate the 13 courses which have been held and the main conclusions of this research. It is concluded that this course has proven educational benefits and effects on clinical practice which include the development of critical reflectivity, acceptance of change, increase in self confidence and an increase in self-directed learning.

Curriculum↗
PubMed1991

Direct polymerase chain reaction test for detection of Helicobacter pylori in humans and animals.

We designed a polymerase chain reaction (PCR) for amplifying the Helicobacter pylori gene encoding 16S rRNA. Primers for the specific detection of H. pylori were designed for areas of the 16S rRNA gene in which there is the least sequence homology between H. pylori and its closest relatives. The specificity of detection was confirmed by ensuring that the primers did not amplify DNA extracts from the campylobacters H. cinaedi, H. mustelae, and Wolinella succinogenes, which are the closest relatives of H. pylori, as determined by 16S rRNA sequencing. Serial dilution experiments revealed the detection of as little as 0.1 pg of DNA by PCR and 0.01 pg by nested PCR. H. pylori DNA was detected successfully in clinical paraffin-embedded and fresh gastric biopsy specimens from patients positive for the bacterium and also in fecal suspensions seeded with the organism. The DNA from the nonculturable coccoid form of H. pylori was also identified by the primers. Universal primers designed for highly conserved areas on the 16S rRNA gene enabled large amplification products to be produced for direct sequencing analysis. Gastric bacteria resembling H. pylori have been isolated from animals. DNA of these animal gastric bacteria amplified with H. pylori-specific primers yielded PCR products identical to those from human isolates of H. pylori, as confirmed by the use of a 20-base radiolabelled probe complementary to an internal sequence flanked by the H. pylori-specific primers. The results of PCR amplification and partial 16S rRNA gene sequence analysis strongly support the contention that the gastric organisms previously recovered from a pig, a baboon, and rhesus monkeys are H. pylori.

Animals↗
PubMed1991

Subjective probability and delay.

Human subjects indicated their preference between a hypothetical $1,000 reward available with various probabilities or delays and a certain reward of variable amount available immediately. The function relating the amount of the certain-immediate reward subjectively equivalent to the delayed $1,000 reward had the same general shape (hyperbolic) as the function found by Mazur (1987) to describe pigeons' delay discounting. The function relating the certain-immediate amount of money subjectively equivalent to the probabilistic $1,000 reward was also hyperbolic, provided that the stated probability was transformed to odds against winning. In a second experiment, when human subjects chose between a delayed $1,000 reward and a probabilistic $1,000 reward, delay was proportional to the same odds-against transformation of the probability to which it was subjectively equivalent.

Adult↗
PubMed1990

Transforming growth factor beta 1 has differential effects on B cell proliferation and activation antigen expression.

There is accumulating evidence that TGF beta 1 is an important immunoregulatory molecule. Here we report evidence that TGF beta 1 has potent effects on murine B cells. It is profoundly inhibitory to the proliferation of quiescent B cells activated in model systems using both thymus-independent and thymus-dependent stimuli and arrests cells predominantly at the G1 cell-cycle stage. It also blocks the proliferation of B cell blasts, with a similar accumulation at stage G1. In parallel with this antiproliferative effect, TGF beta 1 inhibits induction of the expression of a series of "activation Ag" including transferrin receptor, RL388, and Ly-6, in mitogen-stimulated B cells. It also inhibits the induction of Ly-6 expression by IL-4, a nonmitogenic stimulus. In contrast to these negative influences, TGF beta 1 induces modestly increased expression of MHC class II Ag in quiescent B cells, and more marked increases in both B cell blasts and mitogen-stimulated cells. We speculate that in the appropriate context TGF beta 1 may be a cytokine that promotes productive B cell-Th cell interaction.

Animals↗
PubMed1990

Mouse chimeras and genetic rescue of mosaic muscle.

The nuclear-cytoplasmic relationships existing within mosaic muscle will likely determine whether myoblast transfer can effectively rescue diseased muscle. The mouse chimera preparation is one source of such mosaic muscle in which that in vivo relationship can be investigated in the complete absence of complicating immunological or surgical trauma. For several metabolic enzymes, the mature muscle fiber appears to contain a homogeneous mix of the proteins encoded by multiple myonuclei. This relationship is clearly not representative of all muscle proteins, as several examples of proteins highly localized to "nuclear territories" have now been described. Nonetheless, the intrafiber distribution of certain enzymes, particularly GP1-1, is appropriate for the basis of a genotype marking system applicable to mosaic fibers. In vitro rescue of mdg myotubes is readily achievable by incorporation of few normal myonuclei and possibly by only one. In vivo requirements are apparently far more stringent and an hypothesis in which the mdg gene product, a Ca+(+) channel subunit, is restricted to nuclear territories would be consistent with the disparate results obtained in vitro and in vivo. Finally, chimeras containing mdx/mdx cells may show a partial amelioration of muscle pathology and may provide a means of determining the minimum genetically normal myonuclear compliment required to prevent degeneration of dystrophin-deficient fibers.

Animals↗
PubMed1989

Definition of the HLA-Aw43 antigen.

The HLA antigen Aw43 has been observed only in Southern African populations. In order to confirm its identity and clarify its definition, ten cells with this specificity were shipped to laboratories in England, the United States of America and Australia to be tested with the sera from the 10th International Histocompatibility Workshop. The results of tests on nine of these cells which were sufficiently viable indicated that HLA-Aw43 is a distinct serological specificity which could be distinguished from both the A10 cross-reacting group (A25, A26 and Aw34) and A29. The Aw43 specificity segregated in two South African Negro families, and occurred commonly in association with Bw70. The occurrence of HLA-Aw43 in South African Caucasoids, in contrast to its absence in other Caucasoid groups, is probably due to genetic admixture with indigenous South African populations.

Black People↗