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At least 199 records · Page 11Linked to original sources
PubMed2001

Regulated gene expression dictates enamel structure and tooth function.

Enamel is a complex bioceramic tissue. In its final form, enamel is a reflection of the unique molecular and cellular activities occurring during organogenesis. From the ectodermal origins of ameloblasts, their gene activity and protein expression profiles exist for the sole purpose of producing a mineralized shell, almost entirely devoid of protein, deposited over the 'bone-like' dentine. The interface between enamel and dentine is referred to as the dentine enamel junction and it is also unique in its biology. This review article is narrow in its scope. We restrict our review to selected advances in our understanding of the genetic, molecular and structural aspects of enamel biology. We present a model of enamel formation that relates gene expression to the assembly of an extracellular protein matrix that in turn controls the structural hierarchy and mechanical aspects of enamel and the tooth organ.

Amelogenin↗
PubMed2002

Searching literature databases for health care economic evaluations: how systematic can we afford to be?

BACKGROUND: As the health care economic-evaluation literature continues to grow, a need for sound methods to conduct systematic reviews of the existing evidence is emerging. So far, reviews of economic evaluations have relied upon noncomprehensive sources and have adopted simplistic search methods, both likely to lead to biased results. OBJECTIVE: To provide evidence of the performance of alternative approaches for identifying published health care economic evaluations and to illustrate what forms of bias may affect systematic reviews of such studies. METHODS: The sensitivity and specificity of alternative search strategies were tested for the period January to March 1997, using seven major medical and social science literature databases, one economic evaluation database and a published bibliography. Studies were selected blindly by pairs of reviewers (agreement 94.1%-96.5%), using a two-stage procedure. RESULTS: By limiting the scope of a review to Medline and by using appropriate search strategies, researchers may significantly reduce the number of nonrelevant references retrieved by their electronic searches (sensitivity 72%, specificity 75%, compared with more extensive strategies), which require exclusion by manual screening. The yield of searches based on specialized bibliographies and databases may be different because of variations in selection criteria, coverage and time lag for inclusion of references. CONCLUSIONS: Medline is the key source for reviews of economic evaluations. Researchers may select from the search strategies proposed in this paper the one that offers an optimal balance between sensitivity and specificity in relation to the aims of their review. Manual searches and searches of databases other than Medline have a limited incremental yield. The sensitivity of all search strategies increases when tighter methodological standards are set, but more research is needed on methods for identifying methodologically sound studies.

Bias↗
PubMed1991

Dimensional changes in cells and tissues during specimen preparation for the electron microscope.

Studies on dimensional changes incurred during preparation of tissue specimens for the transmission and scanning electron microscopes are reviewed, with emphasis on quantitative measurements pertinent to morphometry and three-dimensional reconstruction. The scope of the review includes fixation, dehydration, plastic embedment, critical-point drying, and freeze-drying. Recommendations are presented for monitoring dimensional changes; a strategy for the choice of method of specimen preparation is outlined.

Artifacts↗
PubMed1998

Malabsorption syndromes.

BACKGROUND/AIMS: Malabsorption syndromes commonly result from a pathological interference of the normal digestive process. There have been major advances in the last 4 years. The purpose of this review is to highlight in the form of a brief summary the most outstanding information available. METHODS: The review was performed based on a medical literature search using MEDLINE (1993-1997), bibliographic reviews of book chapters and review articles. As a consequence of the extensive information incorporated in the period and the limited scope of this review, the review will focus in three aspects: (1) an overview on some clinical aspects of malabsorption; (2) diseases in which predominates the disturbed mucosal phase of the digestive process, and (3) providing information on diagnostic testing regarding malabsorption. RESULTS: Major advances on celiac disease, Whipple's disease, giardiasis, tropical sprue, malabsorption of oligo- and disaccharides, vitamin B12 and bile salts are discussed. New aspects on diagnostic procedures for malabsorption are also presented. CONCLUSION: Although major advances have given a great support to the investigation of malabsorption, yet the syndrome remains a major diagnostic dilemma. Based on the limited availability of most diagnostic tests, a simple and practical diagnostic algorithm is presented.

Bile Acids and Salts↗
PubMed2002

Critical review of the research literature of seating interventions: a focus on adults with mobility impairments.

An expanding area in rehabilitation practice is the prescription of seating interventions for clients with mobility impairments. The goal of this intervention is to enhance comfort and functional performance. The purpose of this paper is to review the body of knowledge from the research literature concerning the effectiveness or impact of seating interventions for adults who have mobility impairments. In this review both the scope and the gaps in the literature are defined to identify areas for future research. Specifically, this review was undertaken to identify what outcomes have been examined and what methods have been used in carrying out the research studies. A content analysis based on the conceptual framework of the modified International Classification of Impairment, Disability, and Handicap (ICIDH) and review guidelines for evaluating the quality of research studies has been helpful in informing future research design in this area. The results of the 16 studies that comprised this review indicate that the majority of research conducted thus far has numerous methodological limitations, which in turn limits the extent to which this body of research can be drawn upon to provide evidence for effectiveness in seating interventions. There was an emphasis on constructs at the impairment level and inadequate attention to functional and psychosocial issues. Recommendations regarding future research required to support this specific type of intervention are presented. This research review is an important first step in facilitating discussion among researchers, clinicians, research funders, and seating device users regarding future priorities for research and development in this practice area.

Activities of Daily Living↗
PubMed1997

Photoreceptor guanylate cyclases: a review.

Almost three decades of research in the field of photoreceptor guanylate cyclases are discussed in this review. Primarily, it focuses on the members of membrane-bound guanylate cyclases found in the outer segments of vertebrate rods. These cyclases represent a new guanylate cyclase subfamily, termed ROS-GC, which distinguishes itself from the peptide receptor guanylate cyclase family that it is not extracellularly regulated. It is regulated, instead, by the intracellularly-generated Ca2+ signals. A remarkable feature of this regulation is that ROS-GC is a transduction switch for both the low and high Ca2+ signals. The low Ca2+ signal transduction pathway is linked to phototransduction, but the physiological relevance of the high Ca2+ signal transduction pathway is not yet clear; it may be linked to neuronal synaptic activity. The review is divided into eight sections. In Section I, the field of guanylate cyclase is introduced and the scope of the review is briefly explained; Section II covers a brief history of the investigations and ideas surrounding the discovery of rod guanylate cyclase. The first five subsections of Section III review the experimental efforts to quantify the guanylate cyclase activity of rods, including in vitro and in situ biochemistry, and also the work done since 1988 in which guanylate cyclase activity has been determined. In the remaining three subsections an analytical evaluation of the Ca2+ modulation of the rod guanylate cyclase activity related to phototransduction is presented. Section IV deals with the issues of a biochemical nature: isolation and purification, subcellular localization and functional properties of rod guanylate cyclase. Section V summarizes work on the cloning of the guanylate cyclases, analysis of their primary structures, and determination of their location with in situ hybridization. Section VI summarizes studies on the regulation of guanylate cyclases, with a focus on guanylate cyclases activating proteins. In Section VII, the evidence about the localization and functional role of guanylate cyclases in other retinal cells, especially in "on-bipolar" cells, in which guanylate cyclase most likely plays a critical role in electrical signaling, is discussed. The review concludes with Section VIII, with remarks about the future directions of research on retinal guanylate cyclases.

Animals↗
PubMed2006

Redox regulatory mechanisms in cellular stress responses.

BACKGROUND: Reactive oxygen species are produced in a highly localized and specific pattern in biological stress responses. The present review examines the redox regulatory aspects of a number of molecular stress response mechanisms in both prokaryotes and eukaryotes. SCOPE: The present review provides examples representing both the cytoplasmic stress response, often studied as the heat shock response, as well as the stress response of the endoplasmic reticulum, known as the unfolded protein response. The examples have been selected to illustrate the variety of ways that redox signals mediate and affect stress responses. CONCLUSIONS: Redox regulatory mechanisms are intricately embedded in both the cytoplasmic and endoplasmic reticulum stress responses at multiple levels. Many different stimuli, both internal and external, activate endogenous production of reactive oxygen species as a necessary part of the intracellular communication system that activates stress responses.

Animals↗
PubMed1981

Drug therapy review in nursing homes: proposed standards and guidelines.

In 1974, the Department of Health, Education, and Welfare mandated monthly drug regimen reviews by pharmacists for all Medicaid-financed residents in skilled nursing facilities. In 1980, proposed federal regulations were developed to extend the benefit of that type of review to residents of intermediate care facilities. The Government Accounting Office, in the meantime, found that a definition of the scope of medication review is still lacking, as is a single source of information on drug monitoring. As the proposed regulations and the corresponding guidelines appear to have severe shortcomings, the authors developed new standards and guidelines for the Baltimore City PSRO. Foremost in these is the statement that drug regimen review is not complete until the physician has responded in writing in the patient's chart to any recommendation the pharmacist-consultant has made.

Aged↗
PubMedDate not supplied

Toward understanding age-related memory loss in late adulthood.

BACKGROUND: While laboratory tests indicate that older adults typically perform more poorly than do younger adults on many types of memory tasks, the question arises as to whether, or to what extent, it is valid to attribute these differences to ageing per se or to some variable or class of variables that intervene between age and remembering. OBJECTIVE: The purpose of this review is to present three current views that might explain the relationship between age and remembering. They can be construed as variants on resource theories and include: the processing speed hypothesis, the executive function hypothesis, and the common cause hypothesis. METHODS: The review samples results pertinent to these hypotheses that derive from behavioural research. Studies involving various imaging techniques were considered beyond the scope of the review. RESULTS: The balance of research strongly implicates reductions in the speed of information processing as a fundamental contributor to normal age-related memory loss. Nonetheless there are circumstances where other mechanisms, such as working memory, executive function, and sensory processes, are important. CONCLUSION: Despite the phenomenological and empirical reality of age-related memory loss and the breadth of attempts to explain it, much work remains to be done to understand why it occurs. Contemporary debates about the nature and means of identifying shared and unique effects promise to shape future directions for research on memory aging.

Adult↗
PubMed1983

The developmentalist and the study of biological risk: a view of the past with an eye toward the future.

This paper has 2 goals: to review the history of the developmental study of infants and children at biological risk and to appraise the current state of the art. The scope of the review is from 1920 to the present and emphasizes the role of developmentalists. 4 research phases are identified, each reflecting aspects of the social, political, health, and psychological zeitgeist. First, from 1920 to World War II, research was primarily "catalog" and had diverse themes; however, several issues were raised that continue to have relevance. Second, during the postwar years, research often focused on the cognitive and emotional residuals of handicaps, particularly cerebral palsy and poliomyelitis. Third, the 1960s marked the funding of major seminal longitudinal investigations of perinatal risk factors, and studies of very young infants "at risk." And fourth, in the last and current period, technological advances of the 1970s first applied to research with normally developing children were then extended to at-risk groups and revolutionized the methods of studying risk. Finally, we suggest that, although a considerable amount of information has been obtained about developmental phenomena subsequent to biological risk, our research literature is fragmented and difficult to synthesize. We conclude by offering strategies to foster research and the integration of knowledge.

Cerebral Palsy↗
PubMed2001

Free radical-induced double lesions in DNA.

This review surveys the work that has been done on free radical-induced DNA double lesions. Double lesions consist of two modifications of the DNA in close proximity. Double lesions can be generated by a single free radical-initiating event and the mechanism of formation often involves the participation of guanine. The identification of double lesions in oligomer and polymer DNA is reviewed and possible mechanisms of formation are outlined. The potential biological significance of double lesions is discussed. Double lesions induced by UV light are outside the scope of this review.

Animals↗
PubMed2002

Safe motherhood in the United States: challenges for surveillance.

OBJECTIVES: Maternal mortality ratios in the United States are higher than those of many other industrialized nations. Moreover, these ratios have not changed in the past 20 years, and large racial disparities persist in measures of both maternal mortality and morbidity. In an affluent developed country, maternal deaths should serve as rare sentinel events, highlighting opportunities for prevention and reduction of morbidities. However, existing surveillance efforts are poorly developed, and pregnancy-related deaths and illnesses tend to be underreported. To formulate recommendations for improved surveillance, the authors reviewed existing data on maternal health. METHODS: This review examines the scope and quality of existing information and the strengths and limitations of definitions of maternal mortality and morbidity used in data collection and reporting. RESULTS: This review suggests numerous gaps in surveillance of U.S. maternal health. Psychological as well as physical morbidity, and the presence and adequacy of appropriate treatment, should be ascertained. Quality of pregnancy-related care at the clinical and community levels, and the impact on mortality and morbidity, must be assessed. Collection of morbidity data outside of health care delivery sites is also essential. Trade-offs between nationally representative and other less comprehensive data sources, such as sentinel clinics, large healthcare organizations, and public healthcare financing systems, should be considered. CONCLUSION: Maternal health remains an important frontier for U.S. public health surveillance efforts. Improved surveillance offers opportunities for reducing pregnancy-related mortality and gaining a better understanding of the relationship between maternal morbidity and mortality.

Databases, Factual↗
PubMed2006

Aromatic O-glycosylation.

Carbohydrates carrying an aromatic aglycon are important natural products and thus key synthetic targets. However, due to the electron-withdrawing properties of aromatic rings, phenols are difficult to glycosylate. This review covers the most common carbohydrate donors used for aromatic O-glycosylation (anomeric acetates, halides, trichloroacetimidates and thioglycosides) as well as some less common donors. The scope of the review is to give practical examples of aromatic O-glycosylations and to offer guidelines for glycosylation of typical aromatic residues. Anomeric acetates or trichloroacetimidates, activated under acidic conditions, are preferred for electron rich aromatic aglycons, while glycosyl halides, activated using basic conditions, are preferred for electron deficient aromatic residues.

Acetamides↗
PubMed2005

Functional abnormalities in isolated arteries from Goto-Kakizaki and streptozotocin-treated diabetic rat models.

Several different rat models have been developed for both type 1 and type 2 diabetes with the aim of displaying specific traits of diabetes. For example, a review on nephropathy associated with type 2 diabetes included 16 different rodent models ; new models are still being developed. The large number of different models developed for different traits makes it difficult to choose the right model for a given study. It is often a problem that the models are not sufficiently characterized, which makes it easy to misinterpret data or even come to the wrong conclusions. In this brief review, we will concentrate on the functional responses obtained in vitro from mesenteric arteries and aortic segments from rat models of diabetes. Since it is beyond the scope of this review to overview all different rodent models of diabetes, we will focus on two commonly used models of diabetes, namely the streptozotocin (STZ)-induced type 1 diabetic rat model and the inbred type 2 diabetic Goto-Kakizaki (GK)-rat model.

Animals↗
PubMed2006

Application of the finite element method in dental implant research.

This article provides a review of the achievements and advancements in dental technology brought about by computer-aided design and the all powerful finite element method (FEM) of analysis. The scope of the review covers dental implants, jawbone surrounding the implant and the biomechanical implant and jawbone interaction. Prevailing assumptions made in the published finite element analysis (FEA) and their limitations are discussed in some detail which helps identify the gaps in research as well as future research direction.

Biocompatible Materials↗
PubMed2006

Preoperative loco-regional imaging in rectal cancer.

Preoperative staging of rectal cancer can influence the choice of surgery and the use of neoadjuvant therapy. This review evaluates the use of endorectal ultrasound (ERUS) and magnetic resonance imaging (MRI) in the local staging of rectal cancer. Staging for distant metastases is beyond the scope of this review. A MEDLINE search for published work in English between 1984-2004 was carried out by entering the key words of ERUS, MRI and preoperative imaging and rectal cancer. Initially, 867 articles were retrieved. Abstracts were reviewed and papers selected according to the inclusion criteria of a minimum of 50 patients and papers published in English. Papers focusing on preoperative chemoradiotherapy and distal metastases were excluded. Thirty-one papers were included in the systematic review. The examination techniques and images obtained are discussed and the respective accuracy is reviewed. ERUS and MRI have complementary roles in the assessment of tumour depth. Ultrasound has an overall accuracy of 82% (T1, 2, 40-100%; T3, 4, 25-100%) and is particularly useful for early localized rectal cancers. MRI has an accuracy of 76% (T1, 2, 29-80%; T3, 4, 0-100%) and is useful in more advanced disease by providing clearer definition of the mesorectum and mesorectal fascia. Both methods have similar accuracy in the assessment of nodal metastases. Ultrasound is more operator dependent and accuracies improve with experience, but it is more portable and accessible than MRI. Improvements in technology and increased operator experience have led to more accurate preoperative staging. ERUS and MRI are complementary and are most accurate for early localized cancers and more advanced cancers, respectively.

Endosonography↗