Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “conception”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,225 records · Page 68Linked to original sources
PubMed1997

Assessing the impact of adolescent pregnancy and the premarital conception stress complex on birth weight among young mothers in Gibraltar's civilian community.

PURPOSE: The objective of this study was to assess the impact of young maternal age and the timing of conception on birth weight among primiparous women living in Gibraltar. METHODS: The data for this study were derived from a population of 295 primiparous women who gave birth under 25 years of age. Only married women who had no previous maternal history and delivered live singleton newborns between 1980 and 1984 were included. The confounding effects of gestation length, sex, and socio-economic status on birth weight were taken into account using the multivariate technique of multiple classification analysis. A conception timing variable was constructed and partitioned into four groups which represented the separate and joint effects of maternal age and prenuptial stress on birth weight. RESULTS: The overall mean birth weight was 3344.15 g. After controlling for the specified factors and covariate, the infants of older mother (> 19) who conceived after marriage weighed 57.78 g above the referent group mean. Older mothers who conceived a child before marriage delivered infants weighing 75.67 below the grand mean. Young mother (< 20) who conceived within marriage had infants who weighed 37.32 g less than the grand mean. Infants delivered by young mothers who conceived before marriage weighed 133.66 g less than the overall mean birth weight. The only significant group difference detected within the conception timing variable was between young mothers who conceived before marriage versus older mothers who conceived after marriage. CONCLUSIONS: Premarital conception is identified as a risk factor for lower infant birth weights among mothers under 20 years of age. This study emphasizes the need to take into account the effects of culturally mediated behavior on the pregnancy experience of young women.

Adolescent↗
PubMed1994

Treatment of submucous fibroids, and outcome of assisted conception.

STUDY OBJECTIVE: To determine the effect of hysteroscopic resection and goserelin in the treatment of submucous fibroids, and their significance in assisted conception. DESIGN: Patients with history of subfertility and previous failed attempts at assisted conception were examined by transvaginal sonography before further attempts at assisted conception. Those diagnosed as having submucous fibroids were treated with goserelin injections, hysteroscopic resection, or a combination of both. Saline sonohysterography was performed whenever the submucous nature of the fibroid was unclear. SETTING: The Churchill Clinic Fertility and IVF Centre, London, United Kingdom PATIENTS: One hundred women being treated for subfertility over a period of 2 years. Twenty-seven had submucous fibroids diagnosed by transvaginal sonography, and a comparable group of 73 had a normal uterine cavity. INTERVENTIONS: Three doses of goserelin 3.6 mg subcutaneously at 4-week intervals were given, followed by hysteroscopic resection of the submucous part of fibroids if the fibroids remained submucous. Three patients had hysteroscopic resection without goserelin, as the fibroids were resectable when they were diagnosed. All patients underwent assisted conception within 3 months unless they conceived spontaneously in the interim. MEASUREMENTS AND MAIN RESULTS: The pregnancy rate in patients with normal uterine cavity was 26%/embryo transfer, and 15.8% of these ended in a miscarriage. The pregnancy rate was significantly higher (p >0.02) in the study group after treatment of submucous fibroids (48.2%/embryo transfer), and the miscarriage rate of 23.1% was not significantly different. CONCLUSIONS: Submucous fibroids are a significant cause of subfertility. A combination of goserelin injections and hysteroscopic resection significantly improves pregnancy rates without increasing the miscarriage rate.

Adult↗
PubMed2003

Context-based ontology building support in clinical domains using formal concept analysis.

OBJECTIVE: Ontology in clinical domains is becoming a core research field in the realm of medical informatics. The objective of this study is to explore the potential role of formal concept analysis (FCA) in a context-based ontology building support in a clinical domain (e.g. cardiovascular medicine here). METHODOLOGY: We developed an ontology building support system that integrated an FCA module with a natural language processing (NLP) module. The user interface of the system was developed as a Protégé-2000 JAVA tab plug-in. A collection of 368 textual discharge summaries and a standard dictionary of Japanese diagnostic terms (MEDIS ver2.0) were used as the main knowledge sources. A preliminary evaluation was taken to show the usefulness of the system. RESULTS: Stability was shown on the MEDIS-based medical concept extraction with high precision. 73+/-14% (mean+/-S.D.) of the compound medical phrases extracted were sufficiently meaningful to form a medical concept from a clinical perspective. Also, 57.7% of attribute implication pairs (i.e. medical concept pairs) extracted were identified as positive from a clinical perspective. CONCLUSION: Under the framework of our ontology building support system using FCA, the clinical experts could reach a mass of both linguistic information and context-based knowledge that was demonstrated as useful to support their ontology building tasks.

Decision Support Systems, Clinical↗
PubMed1999

The concept of the alpha-amylase family: structural similarity and common catalytic mechanism.

This review reconsiders the concept of the alpha-amylase family in the light of the recent wealth of information on the structures, the catalytic mechanisms, and the classification of amylases. We proposed a general concept for an enzyme family, the alpha-amylase family including most of the amylases and related enzymes in 1992, based on the structural similarity and the common catalytic mechanisms. The study on neopullulanase was the key to open the door for the formulation of the concept. We discovered a new enzyme, neopullulanase, and proved that the enzyme catalyzes both hydrolysis and transglycosylation at alpha-1,4- and alpha-1,6-glucosidic linkages by one active center. Results from a series of experiments using neopullulanase indicated that the four reactions mentioned above could be catalyzed in the same mechanism. Progress in X-ray crystallographic analysis has allowed researchers to observe the structural similarities among alpha-amylases, cyclodextrin glucanotransferases, and an isoamylase. The primary structural analyses and the secondary structural predictions also suggest a close relationship among enzymes with three-dimensional structures which catalyze one of the four reactions. They possess a catalytic (beta/alpha)8-barrel as observed in the crystal structure of alpha-amylases, cyclodextrin glucanotransferases, and an isoamylase. Two crucial points, the common catalytic mechanisms and the structural similarities among the enzymes which catalyze the four reactions, led us to propose the concept of the alpha-amylase family. We would like to point out the significance and problems of the sequence-based classification of glycosyl hydrolases. The possible catalytic mechanism of the alpha-amylase family enzyme is also described for the rational design of tailor-made artificial enzymes.

Journal Article↗
PubMed2002

Beyond futility: to what extent is the concept of futility useful in clinical decision-making about CPR?

The concept of futility has often been invoked to justify abstention from treatment and decisions such as 'do not attempt resuscitation' (DNAR). In this capacity, futility has played an important part in the development of several sets of official clinical guidelines. In this paper, we examine the nature of futility and question whether it is a sufficiently robust concept to meet the ethical and clinical demands placed upon it. Although the concept of futility promises simplicity, it cannot stand alone as a satisfactory framework for clinical decision-making. Practitioners and policy makers should be cautious about their use of the concept.

Decision Making↗
PubMedDate not supplied

Concept analysis: an approach to teaching physiologic variables.

Establishment of a knowledge base for nursing practice has been an ongoing goal of nurse professionals for the past decade. Because nurses are especially concerned with management of the body's potential or actual response to illness, the development and use of materials that reflect these body responses seems appropriate. This article is an effort to promote the use of concepts as a basis for nursing practice. A concept analysis approach for didactic instruction, currently being used for organizing and synthesizing pathophysiologic data present in literature, is presented. The process is exemplified by excerpts from the concept "inflammation." Advantages and disadvantages identified by graduate students for the use of concepts and the analysis process as a teaching/learning strategy are included.

Education, Nursing↗
PubMedDate not supplied

An evolutionary concept analysis of mentoring in nursing.

Despite widespread evidence of the concept of mentoring in nursing, it has been largely undefined, borrowed from other disciplines, viewed as static, and/or confused with related terms. Building on the work of Yoder and using a literature-based method developed by Rodgers, an evolutionary concept analysis is presented to provide an understanding of the meaning of mentoring in nursing, its current status, and the conceptual clarity necessary for additional systematic and rigorous inquiry. A random sample of 82 research abstracts and journal articles, representing 26 per cent of the total population of literature, was used to extract six essential attributes of the concept: a teaching-learning process, a reciprocal role, a career development relationship, a knowledge or competence differential between participants, a duration of several years, and a resonating phenomenon. These attributes form the theoretical definition of mentoring in nursing. Antecedents, consequences, related concepts, and empirical referents are presented. A model case, encompassing all of the critical attributes, depicts the Investigators' mentoring experience. Major changes in mentoring are viewed within the context of nursing as a learned profession, a legitimate academic enterprise, and a clinical science. Implications for further development are posed to further mentoring as a process for the socialization of nurse scholars and scientists and the proliferation of a body of professional knowledge.

Education, Nursing, Graduate↗
PubMed1988

Description of the molecular mechanism of cooperativity in human hemoglobin cannot be limited to a first-order free energy coupling concept.

Studies of the linkage between ligand binding and subunit assembly of oligomeric proteins have extensively used the concept of free energy coupling. The "order" of these free energy couplings was introduced [Weber, G. (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 7098-7102] as the number of subunits that must be liganded to alter specific intersubunit interactions. This concept dictates that the ligation of fewer subunits has no effect, but once the order number of subunits becomes ligated, the specific intersubunit interaction energy between those particular subunits is completely eliminated. Weber's report claims that the free energy coupling between oxygen binding and the dimer-tetramer subunit assembly in stripped human hemoglobin A is "first order". This conclusion is based on the analysis of a set of previously published equilibrium constants [Mills, F. C., Johnson, M. L., & Ackers, G. K. (1976) Biochemistry 15, 5350-5362]. I subsequently reported that the original experimental data, from which the equilibrium constants were derived, are consistent with both the first-order and "second-order" free energy coupling concepts [Johnson, M. L. (1986) Biochemistry 25, 791-797]. I also demonstrated that more precise recent experimental data [Chu, A. H., Turner, B. W., & Ackers, G. K. (1984) Biochemistry, 23, 604-617] are consistent with both the first-order and second-order free energy coupling concepts. A recent article [Weber, G. (1987) Biochemistry 26, 331-332] disagrees that the oxygen-binding data for human hemoglobin A are consistent with a second-order model.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemoglobin A↗
PubMedDate not supplied

Metabolic pathway analysis: basic concepts and scientific applications in the post-genomic era.

This article reviews the relatively short history of metabolic pathway analysis. Computer-aided algorithms for the synthesis of metabolic pathways are discussed. Important algebraic concepts used in pathway analysis, such as null space and convex cone, are explained. It is demonstrated how these concepts can be translated into meaningful metabolic concepts. For example, it is shown that the simplest vectors spanning the region of all admissible fluxes in stationary states, for which the term elementary flux modes was coined, correspond to fundamental pathways in the system. The concepts are illustrated with the help of a reaction scheme representing the glyoxylate cycle and adjacent reactions of aspartate and glutamate synthesis. The interrelations between pathway analysis and metabolic control theory are outlined. Promising applications for genome annotation and for biotechnological purposes are discussed. Armed with a better understanding of the architecture of cellular metabolism and the enormous amount of genomic data available today, biochemists and biotechnologists will be able to draw the entire metabolic map of a cell and redesign it by rational and directed metabolic engineering.

Biotechnology↗
PubMed1992

Edward E. Smissman-Bristol-Myers Squibb Award Address. The role of concepts in structure-activity relationship studies of opioid ligands.

Various concepts have served as the basis for the development of models to explore the relationship between molecular structure and biological activity. In this presentation I have outlined five concepts that have been useful in our investigation of opioid receptor multiplicity and in the design of selective opioid receptor antagonists. The first of these, the multiple binding modality concept, led to our application of four other concepts in the development of opioid receptor probes. Some of these probes are now standard tools in opioid research. These include the mu-selective affinity label beta-FNA (10), the kappa opioid receptor antagonist norBNI (15), and the delta opioid antagonist NTI (20). These highly selective antagonists have advantages over the universal opioid antagonists naloxone and naltrexone because they are of value in probing the interaction of endogenous opioid peptides with opioid receptor types. Additionally, they are useful in evaluating the selectivity of new opioid agonists. Also, selective opioid antagonists have potential clinical applications in the treatment of a variety of disorders where endogenous opioids play a modulatory role. These include constipation, immune function, drug addiction, and alcoholism, to name only a few.

Affinity Labels↗
PubMed2000

A comparative study on the oestrous response to PGF2 alpha analogue treatment, and conception rates according to time of artificial insemination, in Zebu (Bos indicus) and Baoulé (Bos taurus) cattle.

The oestrous response, interval and conception rates were studied after synchronization with a prostaglandin analogue (cloprostenol) and artificial insemination (AI) performed at different times in 50 Zebu (Bos indicus) and 83 Baoulé (Bos taurus) cattle indigenous to Burkina Faso. The overall proportion of cows responding to synchronization was 70% (93/133). Although the response was higher for the Baoulé cattle, at 73.5% (61/83), than for the Zebu, at 64% (32/50), the difference was not statistically significant (p > 0.05). The mean oestrous interval from treatment to the onset of oestrus (TOI) was shorter in the Zebu (54.1 h, SD 6.7) than in Baoulé (65.2 h, SD 12.9) cattle (p < 0.001). Of the Zebu (n = 32) that responded, 65.7% presented oestrus over a period of 12 h ranging from 48 h to 60 h after treatment. For the Baoulé cows, the highest proportion of animals in oestrus over a period of 12 h was 41% between 60 h and 72 h after treatment. The frequency distribution of onset of the oestrus indicated that up to 64.5% of the Zebu and 79.5% of the Baoulé cattle showed onset of oestrus during the daytime. For Zebu and Baoulé cows inseminated 13 h or 18 h after the onset of oestrus, conception rates were 56% and 57% (p > 0.05) and 33% and 64% (p < 0.05), respectively. Based on these findings, it appears that the oestrous response to synchronization was adequate for both Zebu and Baoulé cattle and that the time to onset of oestrus varied according to genotype. It was also concluded that conception rates were satisfactory for both genotypes but that, for Baoulé cattle, AI performed 18 h after oestrus significantly increased conception rates compared to AI at 13 h after oestrus.

Animals↗
PubMed1999

Diagnosis and management of dementia in primary care at an early stage: the need for a new concept and an adapted procedure.

Diagnosis of dementia in primary care is both difficult and important. The recommendations by several authors to improve the diagnosis of dementia by general practitioners are important, but insufficient. It is argued that perhaps the disease concept in itself is a cause of confusion for clinicians. Primary care physicians need an adapted procedure, gradually leading to the final diagnosis of dementia. It has to be a stepwise labelling strategy, using global descriptions and non-disease specific labels in the beginning, ending up with well-defined disease criteria. In this process, there is circularity: previous diagnoses have to be kept in mind because symptoms and signs may gradually change during the progression of the disease, leading to reconsideration of previous deleted options. To frame this properly, the primary care physician needs to adopt a broad "frail elderly" geriatric concept. Implementation of this concept not only helps the diagnostic process, but also stimulates the care for dementing patients and their caregivers. Relevant arguments for early diagnostic involvement of primary care physicians can be put forward on condition that a new concept, adapted procedures and adapted instruments are used.

Aged↗
PubMed1998

Problem-Based Learning (PBL): Conceptions and Approaches of Undergraduate Students of Nursing.

Objective: A study aimed at exploring the variation in conceptions of problem-based learning (PBL) held by undergraduate nursing students and their approaches to study in PBL in a pre-registration Bachelor of Nursing Course.Method: Students were asked to respond to four open ended questions which focussed on their experience of PBL in a particular subject. Data were analysed in two phases using a modified phenomenographic analysis. In the first phase a set of categories of description were developed from the student responses. In the second phase the individual responses were classified in terms of the categories. The paper will describe the approach to the analysis, the categories identified, the relationship between the categories and discuss the implications for further research and teaching.Results: The findings indicated that there was a substantial variation in the conceptions and approaches. The majority of students, however, held relatively unsophisticated conceptions of problem based learning which were related to relatively unsophisticated approaches to learning.Conclusion: Students participating in their first PBL subject generally reported unsophisticated conceptions of and approaches to learning which were not linked to professional practice outcomes. However, those completing the last PBL subject had recognised the link between participation in the process and the development of knowledge and skills for professional practice.

Journal Article↗
PubMed1999

The concept of abnormality in medical genetics.

This paper explores usage of the concept of abnormality in medical genetics and proposes directives for more careful usage of this concept. The conceptual difficulties are first explored, then a model is developed to assess actual usage, followed by analysis of a sample of genetic textbooks and genetics literature. It appears that fact and valuation are often intermingled, that reference standards used to define 'genetic abnormalities' are often not clear and that the concept of abnormality is often used independent of the degree of certainty with which the altered genetype develops into a (seriously) harmful phenotype. On the basis of these findings it is argued that more restraint and more careful use of the concept of genetic abnormality of medical genetics is appropriate as well as more agreement on the use of reference standards.

Congenital Abnormalities↗
PubMed2001

Complexity of the concept of disease as shown through rival theoretical frameworks.

The concept of disease has been the subject of a vast, vivid and versatile debate. Categories such as "realist", "nominalist", "ontologist", "physiologist", "normativist" and "descriptivist" have been applied to classify disease concepts. These categories refer to underlying theoretical frameworks of the debate. The objective of this review is to analyse these frameworks. It is argued that the categories applied in the debate refer to profound philosophical issues, and that the complexity of the debate reflects the complexity of the concept itself: disease is a complex concept, and does not easily lend itself to definition.

Disease↗
PubMed2003

Three concepts of suffering.

This paper has three main aims. The first is to provide a critical assessment of two rival concepts of suffering, that proposed by Cassell and that proposed in this journal by van Hooft. The second aim of the paper is to sketch a more plausible concept of suffering, one which derives from a Wittgensteinian view of linguistic meaning. This more plausible concept is labeled an 'intuitive concept'. The third aim is to assess the prospects for scientific understanding of suffering.

Animals↗
PubMed2004

The Archaeal Concept and the World it Lives in: A Retrospective.

The present retrospective concerns the discovery and development of the archaea, the so-called 'third form of life' that no one anticipated and many did not, and still do not want. In its birth pangs, which the archaea had a plenty, the concept encountered biology unmasked; for it ran up against some of the key struts in the 20th century biological edifice. Consequently, the history of the development of the archaeal concept provides an excellent window on certain of the weaknesses in the 20th century biology paradigm, weaknesses that have now led that paradigm to a conceptual dead end. On the other hand, the archaeal concept has also provided us one of the pillars on which a new holistic paradigm for biology can be built. So, it would seem of value to retrace some of the twists and turns in the history of the development of the archaeal concept. Given my position vis-à-vis the archaea, my account will be a personal one.

Journal Article↗
PubMed2006

["Getting through"--a difficult nursing concept].

This analysis of the research literature related to the nursing concept "enduring" was carried out on the background of the demand for evidence based nursing. The aim was to test with an exemplary concept to what extent this request is feasible and meaningful, if related to a concept describing patients' subjective experience. The state of the art of research literature on enduring contains a variety of problematic aspects: conceptual, theoretical, linguistic as well as problems originating in nursing's moral tradition. These have important implications for the application of the concept in nursing practice.

Attitude of Health Personnel↗