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Results for “Continuous Evolution”

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At least 469 records · Page 26Linked to original sources

PubMed1977

Validity of the Ann Arbor staging classification for the non-Hodgkin's lymphomas.

The Ann Arbor staging classification has proved to be valuable for Hodgkin's disease. When proposed in 1971 it was thought that it could also be applied to the non-Hodgkin's lymphomas. The diversity of the non-Hodgkin's groups, the continued evolution of histopathologic classifications, and the great frequency of advanced disease in the lymphocytic subgroups make the Ann Arbor classification of only limited value for the non-Hodgkin's lymphomas.

Bone Marrow↗

PubMedDate not supplied

Increased virulence of Marek's disease virus field isolates.

The continuation of an apparent evolutionary trend of Marek's disease virus (MDV) towards greater virulence may explain recent increased losses from Marek's disease (MD) in vaccinated flocks. To address this question, the virulence of 31 isolates of serotype 1 MDV obtained from layer or broiler flocks between 1987 and 1995 were characterized. Each isolate was cultured in duck embryo fibroblasts for four to six passages, and ascertained to be free from contamination with avian retroviruses, chicken anemia virus, and MDVs of other serotypes. The viruses, along with prototype viruses JM/102W and Md5, were tested for virulence by inoculation at 6 days of age into laboratory strain 15I5 x 7(1) chickens of three types: nonvaccinated, vaccinated with turkey herpesvirus (HVT) and bivalent (HVT + SB-1)-vaccinated. The results showed that three isolates did not differ from JM/102W and were classified in the virulent (vMDV) pathotype. Twenty-one isolates produced significantly higher levels of MD in HVT-vaccinated chickens than did the JM/102W control and were classified in the very virulent (vvMDV) pathotype. Seven isolates, five of which were isolated in 1994 or 1995, produced significantly higher levels of MD in bivalent-vaccinated chickens than did the Md5 (vvMDV) control. These isolates, provisionally designated as the vv+MDV pathotype, appeared to be at the high end of a virulence continuum. Several MD response parameters, including lymphoma mortality, early mortality with bursal/thymic atrophy, and frequency of visceral lymphomas or ocular lesions in nonvaccinated chickens were positively correlated with virulence. These findings support the continued evolution of MDV towards greater virulence.

Animals↗

PubMedDate not supplied

Nucleolar organizer regions (AgNORs) in intraepithelial neoplasia of the uterine cervix.

The authors have studied the AgNORs counts in intraepithelial lesions of the uterine cervix. The following values were obtained (mean +/- SD AgNORs/cell): normal specimens--2.11 +/- 0.98; mild dysplasia--2.83 +/- 1.12; moderate dysplasia--3.42 +/- 1.13; severe dysplasia--3.55 +/- 1.28; carcinoma in situ--4.63 +/- 1.34; glandular extensions of carcinoma in situ--4.64 +/- 0.98. The values in moderate and severe dysplasia were similar, an argument for grouping these categories in the high-grade lesions. AgNORs counts in carcinoma in situ were, however, higher than in severe dysplasia, suggesting a continuous evolution of the neoplastic process.

Female↗

PubMed1997

Update on tendon repair.

The past decade has seen some remarkable advances in the management of acute tendon repair, both flexors and extensors. New surgical techniques, such as the epitenon-first technique for flexor tendons, combined with early motion rehabilitation, pharmacologic intervention to prevent adhesions, and noninvasive imaging techniques such as MR imaging to assess repair integrity lead to one inescapable conclusion. Continued evolution in attempts to improve the overall results of tendon injury can only mean that hand surgeons have not yet reached the perfect solution in tendon repair strategy. Much progress has been made since the era of "no man's land" when primary repair in zone II was in disfavor, but many challenges remain to be met if the "perfect" tendon repair is to be realized.

Hand↗

PubMedDate not supplied

Community action for health promotion: a review of methods and outcomes 1990-1995.

OBJECTIVE: Our objective was to explore the effectiveness of community action as a strategy for health promotion, through a critical review of five years of community action evaluation literature. METHODS: Community action was defined as a health promotion, program that involved the community in implementation and control of the process of the program. Criteria for scientific evaluation of programs were proposed for sampling and control procedures, reliability and validity of instruments, analysis techniques, and specification of details of the intervention. A critical review of the literature, located by an on-line and related reference search, was undertaken for community action aimed at reducing cancer and cardiovascular disease, between January 1990 and May 1995. RESULTS: None of seven community action studies (17 articles) that examined cancer risk factors fulfilled all the criteria for rigorous scientific evaluation. The most methodologically adequate cancer study, the COMMIT intervention, had only a moderate degree of success in reducing community smoking rates. Similarly, none of the six studies (25 articles) on cardiovascular disease fulfilled all the criteria. The results for the most methodologically adequate study, the Minnesota Heart Health Program, were disappointing, with strong secular trends preventing adequate assessment of the intervention effect. CONCLUSIONS: The finding that none of the reviewed studies met all evaluation criteria was due to several factors, including political considerations, feasibility, and the continued evolution of the science of evaluation in health promotion. Some important questions are posed for researchers by the failure of methodologically superior projects, such as COMMIT, to show major gains in reducing health risk behaviors.

Cardiovascular Diseases↗

PubMed1996

The case for an integrated independent physician association.

The State of Georgia has recognized the importance of physicians taking a strong leadership role in managed care with recent legislation allowing physicians to own and present HMO plans directly to employers. Revised antitrust guidelines provide opportunities for physician organizations to take on risk to compete in the HMO/managed care market. Physicians in an IPA have the same ability to access and implement management and information systems as hospitals. Imagine for a moment, attending a performance in the theater, when suddenly an actor rushes on state and shouts: "Is there a hospital administrator in the house?". No one doubts who the central figure in health care should be, if physicians will merely seize the day. We are the best spokespersons on our patient's behalf. With a belief in ourselves and the energy devoted to the integrated IPA format, we are best qualified to manage the continuing evolution of health care delivery in this country.

Decision Making, Organizational↗

PubMed1997

CD7+ and CD56+ myeloid/natural killer cell precursor acute leukemia: a distinct hematolymphoid disease entity.

The disease spectrum of natural killer (NK) cell leukemias and lymphomas has recently been expanding with the continuing evolution in diagnostic concepts. We describe here seven cases of acute leukemia of conceivable myeloid and NK cell precursor phenotype in six men and one woman varying from 19 to 59 years of age (median, 46 years). Striking extramedullary involvement was evident at initial presentation, with peripheral lymphadenopathy and/or mediastinal masses. Two lacked any leukemic cells in the bone marrow at diagnosis. Using cytochemical myeloperoxidase staining, less than 3% of the leukemic cells showed positive reactivity. However, expression of CD7, CD33, CD34, CD56, and frequently HLA-DR, but not other NK, T-cell, and B-cell markers was observed. Cytoplasmic CD3 was detected in three of the cases by flow cytometry and in six by Northern blotting, suggesting an origin from common progenitors between the NK cell and myeloid lineages. All but one presented germline configurations of the T-cell receptor beta and gamma chain genes and Ig heavy chain gene. With regard to morphology, the cells were generally L2-shaped, with variation in cell size, round to moderately irregular nuclei and prominent nucleoli, pale cytoplasm, and a lack of azurophilic granules. Histopathologic examination of biopsied specimens of extramedullary tumors showed a lymphoblast-like morphology, implying the differential diagnostic problem from lymphoblastic lymphomas, especially in cases lacking bone marrow involvement. Three patients were successfully treated with chemotherapy for acute myeloid leukemia (AML), whereas three other patients proved refractory to chemotherapeutic regimens for lymphoid malignancies, although two responded to subsequent AML chemotherapy. However, despite intensive chemotherapy, including allogeneic bone marrow transplantation, most persued fatal courses within 41 months. These data suggested that the CD7+ and CD56+ myeloid/NK cell precursor acute leukemia might constitute a distinct biologic and clinical disease entity. Its recognition appears to be particularly important for the clinicopathologic evaluation of CD56+ hematolymphoid malignancies and the development of therapeutic approaches to such disease.

Acute Disease↗

PubMed1997

Managed care credentialing of advanced practice nurses.

The enormous and rapid changes taking place in health care delivery are forcing institutions, organizations, and individual providers of care to reexamine their relationships and create new methods of assuring both quality of care and safety for consumers. One result has been the emphasis on systematic methods of credentialing, privileging, and measuring and evaluating an individual's qualifications and actual performance. This article discusses the credentialing and privileging processes that are either in place or evolving for physicians in the managed care health care systems. With the continued evolution of managed care in this country, advanced practice nurses may need to expand their credentialing process. This article provides information on the evolutionary events leading to credentialing and privileging, current and anticipated credentialing measures, sources of measurements, medicolegal issues, and suggestions for expansion of nurse credentialing. A comprehensive credentialing system will provide additional evidence of the nursing profession's capacity to play a major role in the reformed health care system.

Credentialing↗

PubMed1996

[Quality assurance in food production in Europe according to ISO 90000 and HACCP (Hazard Analysis and Critical Control Points)].

HACCP is intended to make food protection programs evolve from a mainly retrospective quality control toward a preventative quality assurance approach and to provide an increased confidence in food safety. In parallel, the continuous evolution of quality concepts in the food industry resulted in the development of quality systems and quality assurance techniques with regard to the EN 29,000 (ISO 9000) series of standards. Specific to the food industry, HACCP can be seen as a very effective method to prepare specific Safety Assurance Plans (cf. the quality assurance plan concept) within a quality systems approach (Jouve, 1993). By reference to ISO 8402, a Quality Assurance Plan (QAP) basically sets out "the specific quality practices, resources and sequence of activities relevant to a particular product, service, contract or project". Quality assurance plans are more particularly useful for projects relating to new products or processes and/or comprising inter-related tasks whose interaction may be complex. In addition, in contractual or regulatory situations, such plans can be used to demonstrate the supplier's capability to meet identified objectives, specification or standards. In the food industry, the management of safety is a critical and complex issue which fits very well in the scope of application of a specific QAP; it is also where the use of HACCP is otherwise recommended by priority.

Food Contamination↗

PubMed1998

Overview of diffusion imaging.

Diffusion is a major advance in the continuing evolution of MR imaging. It provides contrasts and characterization between tissues at a cellular level that may imply differences in function as well as framework. With the development of echo-planar imaging (EPImh54) diffusion the quality of the data will be such that clinically relevant information can result, and thus clinical usage of EPI diffusion will increase. Many potential applications of diffusion have not yet been explored.

Brain↗

PubMed1998

New trends in antimicrobial development.

The continual evolution of microbial resistance to the available classes of antibiotics poses a serious threat to the efficacy of traditional antibacterial therapy. Today, there are two main approaches that are being applied to discover better and more effective anti-infective agents against common as well as resistant pathogens: (a) the improvement of the "classical" antimicrobial agents by targeting the so called "resistance factors", and (b) the search of new anti-infective agents with novel modes of actions. This review will highlight the most relevant aspects of both of these approaches and some of the latest findings in the field of antimicrobial discovery.

Anti-Bacterial Agents↗

PubMed1997

[Benign laryngotracheal stenoses in pediatric age].

The diagnosis and treatment of infants and children with laryngo-tracheal pathology has changed substantially over the last 20 years. The change is the result of the continued evolution of diagnostic instruments, surgical techniques and new advancements in critical care medicine. Abnormalities in the development of the larynx may lead to congenital subglottic stenosis. A variety of pathogenic processes, either inflammatory or iatrogenic, also may damage the cricoid cartilage and lead to subglottic stenosis. The stenosis may involve alone or in combination the subglottis, glottis, upper cervical trachea. In this article the author reports a 12 years experience in 114 patients affected by benign laryngo-tracheal stenosis. These patients are classified in two groups: 1) 75 patients with congenital stenosis, 2) 39 patients with acquired stenosis. For the diagnose video-endoscopy has been used, and for the classification the Cotton's technique has been used. To get the best results in this pathology it is very important to have a multidisciplinary approach.

Child↗

PubMed1998

[Severe malaria].

Falciparum malaria remains a major killer in developing countries, particularly for African children. The sequestration of parasitized erythrocytes in the deep microvasculature is mostly mediated by their cytoadherence to activated endothelium. Proinflammatory cytokines and particularly tumor necrosis factor contribute to severe disease but the pathophysiology of coma remains poorly understood. In young children, features of severe malaria include severe anemia, hypoglycemia and cerebral malaria. Half of the children with neurological impairment actually have raised intracranial pressure, and seizures are extremely common. Clinical respiratory distress usually reflects severe lactic acidosis. In non immune adults, pictures of severe sepsis with shock, acute renal failure and respiratory distress syndrome are common and often associated with bacterial coinfection. Although chemotherapy of malaria is challenged by the continuing evolution of antimalarial resistance, quinine remains the first-line drug for severe disease. The optimization of symptomatic management of severe malaria remains a major concern in developing countries.

Adult↗

PubMedDate not supplied

The art of nursing: the client-nurse relationship as a therapeutic tool.

The C-N relationship is the cornerstone and essence of mental health/psychiatric nursing. However, that process has the same potential for nursing in general. The C-N relationship is an interpersonal, interactive, and ongoing relationship set up to assist clients in the continuous evolution toward quality health and well-being. Although this article focuses primarily on the mental health population, the value of a positive working C-N relationship is paramount in addressing all health care issues. The C-N relationship is, indeed, a therapeutic tool that can generate positive side effects, enhance treatment approaches, and greatly influence favorable health care outcomes. It is easy to apply, is flexible, and, when used effectively, can generate the power within health care situations to determine desired health care outcomes.

Empathy↗

PubMedDate not supplied

[Thermodynamics of aging].

The findings of macrothermodynamics (supramolecular thermodynamics) of quasi-closed systems and the published data about the variation of the chemical composition of living organisms in ontogeny confirm the thermodynamic tendency of aging processes. According to the thermodynamic theory, the specific value of the Gibbs function of the formation of supramolecular structures of the organism tends to a minimum. That tendency explains the variation of supramolecular and chemical composition and the morphology of tissues during aging. Thermodynamic theory makes it possible to define the principles upon which proper diets and medications can be devised to slow down aging. Such diets and medications are also useful in preventative care and in the treatment of various pathologies, including those related to old age. The chemical stability of the supramolecular structures of tissues makes it possible to understand the causes of the essentially continuous evolution of the biological world from the perspective of the second law of thermodynamics.

Aging↗

PubMed2024

An Orthogonal T7 Replisome for Continuous Hypermutation and Accelerated Evolution in E. coli.

Systems that perform continuous hypermutation of designated genes without compromising the integrity of the host genome can dramatically accelerate the evolution of new or enhanced protein functions. We describe an orthogonal DNA replication system in E. coli based on the controlled expression of the replisome of bacteriophage T7. The system replicates circular plasmids that enable high transformation efficiencies and seamless integration into standard molecular biology workflows. Engineering of T7 DNA polymerase yielded variant proteins with mutation rates of 1.7 × 10 -5 substitutions per base in vivo - 100,000-fold above the genomic mutation rate. Continuous evolution using the mutagenic T7 replisome was demonstrated by expanding the substrate scope of TEM-1 β-lactamase and increase activity 1,000-fold against clinically relevant monobactam and cephalosporin antibiotics in less than one week.

Journal Article↗

PubMed2025

An orthogonal T7 replisome for continuous hypermutation and accelerated evolution in E. coli.

Systems that perform continuous hypermutation of designated genes without compromising the integrity of the host genome can substantially accelerate the evolution of new or enhanced protein functions. We describe an orthogonal DNA replication system in Escherichia coli based on the controlled expression of the replisome of bacteriophage T7 (T7-ORACLE). The system replicates circular plasmids that enable high transformation efficiencies and seamless integration into standard molecular biology workflows. Engineering of T7 DNA polymerase yielded variant proteins with mutation rates of 1.7 × 10-5 substitutions per base in vivo-100,000-fold above the genomic mutation rate. We demonstrated continuous evolution using the T7 replisome by expanding the substrate scope of TEM-1 β-lactamase and increasing activity 5000-fold against clinically relevant monobactam and cephalosporin antibiotics in less than 1 week.

Bacteriophage T7↗

PubMed2005

The promise and peril of continuous in vitro evolution.

Experimental evolution methods can be used to address and illuminate issues central to the understanding of evolutionary theory. One of the most powerful of these methods involves the in vitro evolution of nucleic acid enzymes, taking advantage of the direct relationship between the genotype of a nucleic acid sequence and the phenotype of its associated catalytic function. This review and commentary focuses on the past, present, and future potential of systems for the continuous in vitro evolution of nucleic acid enzymes as tools for modeling evolutionary processes in biology. It offers a candid appraisal of both the strengths and the limitations of these systems.

Directed Molecular Evolution↗