Genetic and Phenotypic Analysis of Ovule Development in Arabidopsis.

The plant seed is a remarkable structure that represents the single most important energy source in global diets. The stages of reproductive growth preceding seed formation are particularly important since they influence the number, size, and quality of seed produced. The progenitor of the seed is the ovule, a multicellular organ that produces a female gametophyte while maintaining a range of somatic ovule cells to protect the seed and ensure it receives maternal nourishment. Ovule development has been well characterized in Arabidopsis using a range of molecular, genetic, and cytological assays. These can provide insight into the mechanistic basis for ovule development, and opportunities to explore its evolutionary conservation. In this chapter, we describe some of these methods and tools that can be used to investigate early ovule development and cell differentiation.

The RNA-dependent DNA methylation pathway is required to restrict SPOROCYTELESS/NOZZLE expression to specify a single female germ cell precursor in Arabidopsis.

In higher plants, the female germline is formed from the megaspore mother cell (MMC), a single cell in the premeiotic ovule. Previously, it was reported that mutants in the RNA-dependent DNA methylation (RdDM) pathway might be involved in restricting the female germline to a single nucellus cell. We show that the DRM methyltransferase double mutant drm1drm2 also presents ectopic enlarged cells, consistent with supernumerary MMC-like cells. In wild-type ovules, MMC differentiation requires SPOROCYTELESS/NOZZLE (SPL/NZZ), as demonstrated by the spl/nzz mutant failing to develop an MMC. We address the poorly understood upstream regulation of SPL/NZZ in ovules, showing that the RdDM pathway is important to restrict SPL/NZZ expression. In ago9, rdr6 and drm1drm2 mutants, SPL/NZZ is expressed ectopically, suggesting that the multiple MMC-like cells observed might be attributable to the ectopic expression of SPL/NZZ. We show that the ovule identity gene, SEEDSTICK, directly regulates AGO9 and RDR6 expression in the ovule and therefore indirectly regulates SPL/NZZ expression. A model is presented describing the network required to restrict SPL/NZZ expression to specify a single MMC.

Translating auxin responses into ovules, seeds and yield: Insight from Arabidopsis and the cereals.

Grain production in cereal crops depends on the stable formation of male and female gametes in the flower. In most angiosperms, the female gamete is produced from a germline located deep within the ovary, protected by several layers of maternal tissue, including the ovary wall, ovule integuments and nucellus. In the field, germline formation and floret fertility are major determinants of yield potential, contributing to traits such as seed number, weight and size. As such, stimuli affecting the timing and duration of reproductive phases, as well as the viability, size and number of cells within reproductive organs can significantly impact yield. One key stimulant is the phytohormone auxin, which influences growth and morphogenesis of female tissues during gynoecium development, gametophyte formation, and endosperm cellularization. In this review we consider the role of the auxin signaling pathway during ovule and seed development, first in the context of Arabidopsis and then in the cereals. We summarize the gene families involved and highlight distinct expression patterns that suggest a range of roles in reproductive cell specification and fate. This is discussed in terms of seed production and how targeted modification of different tissues might facilitate improvements.

Exploring heterogeneity in clinical trials with latent class analysis.

Case-mix is common in clinical trials and treatment effect can vary across different subgroups. Conventionally, a subgroup analysis is performed by dividing the overall study population by one or two grouping variables. It is usually impossible to explore complex high-order intersections among confounding variables. Latent class analysis (LCA) provides a framework to identify latent classes by observed manifest variables. Distal clinical outcomes and treatment effect can be different across these classes. This paper provides a step-by-step tutorial on how to perform LCA with R. A simulated dataset is generated to illustrate the process. In the example, the classify-analyze approach is employed to explore the differential treatment effects on distal outcomes across latent classes.

Approaching the biology of human parental attachment: brain imaging, oxytocin and coordinated assessments of mothers and fathers.

Brain networks that govern parental response to infant signals have been studied with imaging techniques over the last 15 years. The complex interaction of thoughts and behaviors required for sensitive parenting enables the formation of each individual's first social bonds and critically shapes development. This review concentrates on magnetic resonance imaging experiments which directly examine the brain systems involved in parental responses to infant cues. First, we introduce themes in the literature on parental brain circuits studied to date. Next, we present a thorough chronological review of state-of-the-art fMRI studies that probe the parental brain with a range of baby audio and visual stimuli. We also highlight the putative role of oxytocin and effects of psychopathology, as well as the most recent work on the paternal brain. Taken together, a new model emerges in which we propose that cortico-limbic networks interact to support parental brain responses to infants. These include circuitry for arousal/salience/motivation/reward, reflexive/instrumental caring, emotion response/regulation and integrative/complex cognitive processing. Maternal sensitivity and the quality of caregiving behavior are likely determined by the responsiveness of these circuits during early parent-infant experiences. The function of these circuits is modifiable by current and early-life experiences, hormonal and other factors. Severe deviation from the range of normal function in these systems is particularly associated with (maternal) mental illnesses - commonly, depression and anxiety, but also schizophrenia and bipolar disorder. Finally, we discuss the limits and extent to which brain imaging may broaden our understanding of the parental brain given our current model. Developments in the understanding of the parental brain may have profound implications for long-term outcomes in families across risk, resilience and possible interventions. This article is part of a Special Issue entitled Oxytocin and Social Behav.

Progress on the paternal brain: theory, animal models, human brain research, and mental health implications.

With a secure foundation in basic research across mammalian species in which fathers participate in the raising of young, novel brain-imaging approaches are outlining a set of consistent brain circuits that regulate paternal thoughts and behaviors in humans. The newest experimental paradigms include increasingly realistic baby-stimuli to provoke paternal cognitions and behaviors with coordinated hormone measures to outline brain networks that regulate motivation, reflexive caring, emotion regulation, and social brain networks with differences and similarities to those found in mothers. In this article, on the father brain, we review all brain-imaging studies on PubMed to date on the human father brain and introduce the topic with a selection of theoretical models and foundational neurohormonal research on animal models in support of the human work. We discuss potentially translatable models for the identification and treatment of paternal mood and father-child relational problems, which could improve infant mental health and developmental trajectories with potentially broad public health importance.

Applications and computational strategies for the two-point mixture index of fit.

Although numerous descriptive measures have been proposed for assessing model fit when analysing frequency tables, the two-point mixture index of fit proposed by Rudas, Clogg, and Lindsay possesses features that make this index especially appealing in many applied research settings. In particular, the index has an intuitive interpretation that does not depend upon the specific nature of the model being assessed and is not sensitive to sample size. Also, the index can be applied when models are fitted to virtually any frequency table. This paper summarizes the underlying theory and addresses issues of estimation for goodness-of-fit tests for one-way or multi-way frequency tables as well as for certain latent variable models. In addition, a new approach for estimating a lower confidence bound for the index is presented.

Information criteria for pairwise comparisons.

A new approach is presented for the interpretation of differences among means and proportions. Post hoc techniques, such as Tukey's honestly significant difference procedure, have interpretive problems related to intransitive decisions and technical issues arising from unequal sample sizes or heterogeneity of variance. These concerns can be avoided by considering ordered subsets of means and by using information criterion to select among competing models. This paired-comparisons information-criterion (PCIC) approach is wholistic in nature and does not depend on interpreting a series of statistical tests. Simulation results suggest that a protected version of the PCIC procedure is desirable to minimize failures to detect the null case. This technique is illustrated for independent means, proportions, and means from repeated measures.

Asthma patient education: current utilization in pulmonary training programs.

The national guidelines for the diagnosis and management of asthma published in April of 1997 emphasized patient education in asthma management. It is unclear how often patient education is included in asthma management clinics. We sought to determine how often education programs are available by surveying teaching hospitals with training programs in pulmonary and critical care medicine. Using this survey, we also determined the reason programs are not offered and whether computer resources are routinely available to utilize computer-delivered patient educational materials. We sent mail questionnaires to 163 training programs in the United States. We had a response rate of 72% (117 of 163). Of the 117 programs responding, 75 (64%) reported having a formal asthma patient education program. Most (72%) were in university teaching hospitals. A majority of respondents (84%) believed that compensation for their efforts was inadequate, and those hospitals with no formal asthma education program reported that financial cost and time requirements were the primary reasons for not having such a program. Despite the fact that many programs did not have a patient education component, 96% (72 of 75) of respondents with an educational program viewed patient education as an effective patient self-management tool. Of all programs surveyed, 85% reported they would use a high-quality computer-based asthma education program if one was available. Implementation of such a program is feasible, with 69% of programs surveyed having a personal computer in their clinic and 60% having Internet access. We conclude that most training directors believe that patient asthma education is important and effective; however, cost and time issues remain barriers to its implementation. Computer-based educational programs delivered over the Internet are feasible, could address some of these limitations, and are acceptable to most programs.

Telomerase activity in B-cell non-Hodgkin lymphoma.

BACKGROUND: Studies have shown telomerase activity to be present in some B-cell non-Hodgkin lymphomas (B-NHLs). However, no large studies have assayed telomerase activity in a systematic and quantitative manner. Furthermore, the relation between telomerase and proliferation suggested by in vitro studies has not been adequately tested in B-NHLs in vivo. This information is necessary to understand the relation between proliferation and telomerase and to predict the efficacy of antitelomerase drugs currently in development. METHODS: Eighteen benign biopsies and 111 B-NHLs of varying types were classified according to the revised European-American classification of lymphoid neoplasms (REAL classification) and assayed for telomerase activity and proliferation index (PI). RESULTS: All B-NHLs contained telomerase activity except for low grade marginal zone B-cell lymphomas (MZBCLs) (96 of 111, 86%) (chi(2) 95.90, P < 0.001). Telomerase activity correlated with PI (r = 0.7536, r(2) = 0.5678, t = 10.51, P < 0.001) and showed a threshold whereby telomerase activity was not present below a PI of 9.2% (t = 4.875, P < 0.001). CONCLUSIONS: The level of telomerase activity fell within characteristic ranges and generally correlated with the clinical aggressiveness of each B-NHL category. Low grade MZBCLs of extranodal, nodal, and splenic types were unique among the categories of B-NHL in lacking or containing very little telomerase activity. The association between telomerase activity and PI is evidence that telomerase is controlled in vivo along with the cell cycle and is not constitutively active in B-NHL. These data provide evidence that antitelomerase drugs may be efficacious in most types of B-NHL.

A model intervention for elder abuse and dementia.

This article describes a 2-year collaborative project in Cleveland, OH, that improved the reporting and management of potential and suspected elder abuse situations involving persons with dementia. Educational curricula for cross-training, screening tools, and referral protocols were developed and tested for staff and volunteers in adult protective services and dementia care. A handbook for caregivers of persons with dementia was produced that enables caregivers to self-identify elder abuse risk and seek appropriate interventions to prevent abuse. Project organization, implementation, and evaluation are discussed along with strategies for replication in other communities.

Evaluation of an Internet-based decision-support system for applying the ATS/CDC guidelines for tuberculosis preventive therapy.

Preventive therapy for patients infected with tuberculosis (TB) remains an important component of TB control. To guide physicians in applying preventive therapy, the American Thoracic Society and Centers for Disease Control (ATS/CDC) developed guidelines based on PPD reactivity and on pretest probability of infection. The guidelines have become complex, and many clinicians find them challenging to apply. The authors developed a computerized decision-support system to assist clinicians in applying the ATS/CDC guidelines. This tool, published on the World Wide Web using hypertext markup language, delivers patient-specific recommendations based on physician-delivered patient-specific information. Four local TB experts derived eight TB infection scenarios and validated the web-based tool, which was tested for effectiveness using general internal medicine residents, randomly divided into two groups. Group A (n = 12) used the web-based tool and group B (n = 17) used pre-existing understanding of the guidelines and/or written resources to determine the need for preventive therapy in the case scenarios. Group A correctly used therapy in 92/96 possible cases (95.8%), group B in only 77/136 (56.6%) (p < 0.001). Group A required a mean of three mouse-clicks and 1.5 minutes per scenario to reach their choices, and they rated the web-based tool both intuitive and effective. These data demonstrate that a computer-based decision-support system for applying TB treatment guidelines can be delivered over the Internet and provide an efficient and effective resource for clinicians.

Asthma guidelines: an assessment of physician understanding and practice.

In 1997 the NHLBI updated guidelines for the diagnosis and management of asthma. We hypothesized that not all components of the updated guidelines are well understood by the physicians who care for asthmatics. To develop appropriate educational interventions that address areas of physician misunderstanding, it is important to identify these components. Based upon NHLBI guidelines, we developed a multiple-choice test of asthma knowledge that was distributed to physicians at the University of Iowa; 108 physicians completed the test, including 20 asthma specialists, 11 asthma specialty fellows, 11 General Medicine faculty, five Family Medicine faculty, 51 Internal Medicine residents, and five Family Medicine residents. The mean correct total score for all physicians was 60 +/- 2% (mean +/- SEM). Asthma specialists scored higher in total score and in pharmacology and prevention. However, no group performed well on estimating disease severity. We further identified deficits in the use of spirometry and anti-inflammatory agents in caring for asthmatic patients. Thus, deficits exist in physician understanding and implementation of the NHLBI guidelines for the diagnosis and management of asthma. By identifying specific areas of misunderstanding, we can design better educational interventions. Clearly, educational programs should emphasize new models for estimating chronic disease severity.

Realizing the promise: delivering pulmonary continuing medical education over the Internet.

STUDY OBJECTIVES: Continuing medical education (CME) is meant to bridge the gap between new scientific observations and clinical practice. However, traditional CME has not been effective at altering the behaviors of physicians. One reason for this failure of traditional CME programs may be their inflexibility. In traditional CME, the clinician does not choose the topic, the pace of the program, or the place of learning, and the CME material cannot be easily delivered to the point of care where the clinician needs the information. Computers and computer networks have the potential to accomplish these goals. CME has begun to appear on the Internet; however, there have been few evaluations of its usefulness, acceptance, and effectiveness. Over the last 18 months, we have developed three on-line pulmonary CME programs, and we have delivered them on the Virtual Hospital, the University of Iowa's digital health sciences library on the Internet. We report our initial experience with this CME material. DESIGN: We measured the frequency with which the Internet-delivered CME is accessed by monitoring page accessions and by using a log file analysis program (Analog 1.2.3; University of Cambridge Statistical Laboratory; Cambridge, UK). In addition, we collected all completed CME examinations and evaluation forms submitted by registered users. MEASUREMENTS AND RESULTS: We have found that the frequency with which the Internet-delivered CME is accessed has continued to increase with time (2.3-fold increase over 18 months), that evaluations of technical and content issues are strongly favorable, and that some clinicians have been willing to pay to receive CME through the medium of the Internet. CONCLUSIONS: We feel that with adequate peer review and quality control, physicians will use the Internet-delivered CME. However, several obstacles to wide use remain. These obstacles include issues regarding training in using the Internet for physicians, reluctance of physicians to participate in on-line commerce, and the current unavailability of CME to be delivered in small-grained quantities to the point of care. As these issues are addressed, we feel that on-line CME will represent an increasingly important CME medium for clinicians.

Evaluation of internet-based clinical decision support systems.

BACKGROUND: Scientifically based clinical guidelines have become increasingly used to educate physicians and improve quality of care. While individual guidelines are potentially useful, repeated studies have shown that guidelines are ineffective in changing physician behavior. The Internet has evolved as a potentially useful tool for guideline education, dissemination, and implementation because of its open standards and its ability to provide concise, relevant clinical information at the location and time of need. OBJECTIVE: Our objective was to develop and test decision support systems (DSS) based on clinical guidelines which could be delivered over the Internet for two disease models: asthma and tuberculosis (TB) preventive therapy. METHODS: Using open standards of HTML and CGI, we developed an acute asthma severity assessment DSS and a preventative tuberculosis treatment DSS based on content from national guidelines that are recognized as standards of care. Both DSS's are published on the Internet and operate through a decision algorithm developed from the parent guidelines with clinical information provided by the user at the point of clinical care. We tested the effectiveness of each DSS in influencing physician decisions using clinical scenario testing. RESULTS: We first validated the asthma algorithm by comparing asthma experts' decisions with the decisions reached by nonpulmonary nurses using the computerized DSS. Using the DSS, nurses scored the same as experts (89% vs. 88%; p = NS). Using the same scenario test instrument, we next compared internal medicine residents using the DSS with residents using a printed version of the National Asthma Education Program-2 guidelines. Residents using the computerized DSS scored significantly better than residents using the paper-based guidelines (92% vs. 84%; p <0.002). We similarly compared residents using the computerized TB DSS to residents using a printed reference card; the residents using the computerized DSS scored significantly better (95.8% vs. 56.6% correct; p<0.001). CONCLUSIONS: Previous work has shown that guidelines disseminated through traditional educational interventions have minimal impact on physician behavior. Although computerized DSS have been effective in altering physician behavior, many of these systems are not widely available. We have developed two clinical DSS's based on national guidelines and published them on the Internet. Both systems improved physician compliance with national guidelines when tested in clinical scenarios. By providing information that is coupled to relevant activity, we expect that these widely available DSS's will serve as effective educational tools to positively impact physician behavior.

The motivation for drug abuse treatment: testing cognitive and 12-step theories.

The purpose of this paper is to evaluate two models of behavior change: cognitive theory and 12-step theory. Research subjects were drawn from three separate, but parallel, samples of adults. The first sample consisted of out-of-treatment chronic drug users, the second consisted of drug users who had applied for treatment at a publicly funded multiple-provider drug treatment facility, and the third consisted of drug users who had applied for treatment at an intensive outpatient program for crack cocaine users. Cognitive theory was supported. Study participants applying for drug abuse treatment reported a higher level of perceived problem severity and a higher level of cognitive functioning than out-of-treatment drug users. Two hypotheses drawn from 12-step theory were not supported. Treatment applicants had more positive emotional functioning than out-of-treatment drug users, and one treatment-seeking sample had higher self-esteem.

Sudden infant death with external airways covered: case-comparison study of 206 deaths in the United States.

OBJECTIVE: To study factors associated with sudden infant deaths occurring with the external airways (ie, nose and mouth) covered by bedding. DESIGN: Case-comparison study of infants dying with vs those dying without the external airways covered. SETTING: Death-scene investigation and reconstruction at the site of death using an infant mannequin; 18 metropolitan areas. PARTICIPANTS: Caregivers for a consecutive sample of infants who died of sudden infant death syndrome (SIDS). Complete data from 206 of 382 eligible cases. MAIN OUTCOME MEASURES: Among infants dying suddenly and unexpectedly, an analysis of whether sociodemographic risk factors for SIDS, sleep practices, or bedding increased the risk of dying with the external airways covered. RESULTS: Data were analyzed by using univariate and 2 types of multivariate risk analysis, logistic regression and latent class. Of the victims, 59 (29%) were found with the external airways covered. Conventional risk factors for SIDS did not affect the risk of death with the external airways covered. Factors increasing the risk of death with the external airways covered included prone sleep position (odds ratio [OR], 2.86) and using soft bedding (OR, 5.28), such as comforters (OR, 2.46) and pillows (OR, 3.31). Infants at low risk for death with the external airways covered slept in the prone position, but rarely on a pillow, comforter, or other bedding that allowed a pocket to form beneath the face. All 9 infants who were positioned supine or on one side for sleep and found with the external airways covered had turned and were found dead in the prone position. CONCLUSIONS: Sudden infant deaths with the external airways covered were common in the United States when most infants slept prone. Soft bedding, including pillows and comforters, increased the risk that an infant who died would be found with the external airways covered. Therefore, these items should not be placed near infants, regardless of the sleep position.

Conceptualizing oral health and oral health-related quality of life.

This investigation considers oral health from a health-related quality of life perspective using a multidimensional concept representing a combination of impairment, function, perceptions, and/or opportunity. A subset of dentate individuals aged 18 and older from a national probability sample of the U.S. was selected for the reported analysis with data available from personal interviews, self-administered questionnaires, and oral examinations. Impairment was represented by clinically assessed active diseases and sequelae of diseases and self-reported acute symptoms. Other domains are represented by self-reported problems with function, perception of control over oral health, satisfaction with teeth, value attributed to oral health, and opportunity to obtain dental care. Principal components analysis with varimax rotation provided a structure to interpret four factors: accumulated oral neglect, self-perceived symptoms and problems, reparable oral diseases, and oral health values and priorities. Approximately 50% of the variance was explained by these four factors. Factor-based scores, envisioned as an index or summary measure representing the combination of variables identified in each factor, were used to assess potential validity. Whites had lower levels of accumulated oral neglect, fewer symptoms, and less reparable oral disease, but similar oral health values, than non-whites. Level of formal education was associated with each of the four factor-based scores. Age was directly associated with accumulated oral neglect, but the youngest age group had significantly more reparable oral diseases. Individuals with a dental visit in the past two years had considerably less accumulated oral neglect, fewer self-perceived problems, less reparable oral disease, and higher values of oral health than those without a dental visit in the past two years. Ordinary least square regressions were performed on each of the four factor-based scores using eight sociodemographic and economic variables. All four regression models were significant, with only the education variable being significant across all models. These analyses provide no evidence for one unique factor representing oral health. Rather, a conceptual framework for oral health appears to be represented by a set of reasonably independent components, including two groups of clinically assessed oral health, which together more fully represent oral health than any one single variable. Conceptualizing and measuring oral health multidimensionally leads us closer to examining it as part of general health.

Patients with an abnormal chest radiograph and latent tuberculosis.

Patients with latent tuberculosis characterized by a positive tuberculin (purified protein derivative) skin test and radiographic evidence of fibronodular changes or silicosis are at increased risk for the development of active tuberculosis. Before preventive therapy is initiated, the radiographic abnormalities must be differentiated from those representing active disease. According to recommendations from the American Thoracic Society and the Centers for Disease Control and Prevention, patients with latent tuberculosis who exhibit fibronodular changes or silicosis on chest radiographs should be given either isoniazid alone for one year or the combination of isoniazid and rifampin for four months, preferably with pyrazinamide for the first two months. Patients with similar radiographic findings and sputum or culture evidence of active tuberculosis require full multidrug therapy.

Effect of drug user treatment on psychosocial change: a comparison of in-treatment and out-of-treatment cocaine users.

A panel study of 189 in-treatment and 297 out-of-treatment "heavy" drug users was used to evaluate the hypothesis that drug users who participated in drug user treatment would have a greater degree of psychosocial improvement than those who did not participate in treatment. Although time in treatment was significantly associated with improvements in all three domains, a simple path model suggested that changes in cognitive functioning may have mediated changes in self-esteem and emotional functioning. These results indicate that treatment does produce psychological change, and they hint that the cognitive domain may drive most of this change.