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PubMed1997

Implicit representation in genetic algorithms using redundancy.

A new representation combining redundancy and implicit fitness constraints is introduced that performs better than a simple genetic algorithm (GA) and a structured GA in experiments. The implicit redundant representation (IRR) consists of a string that is over-specified, allowing for sections of the string to remain inactive during function evaluation. The representation does not require the user to prespecify the number of parameters to evaluate or the location of these parameters within the string. This information is obtained implicitly by the fitness function during the GA operations. The good performance of the IRR can be attributed to several factors: less disruption of existing fit members due to the increased probability of crossovers and mutation affecting only redundant material; discovery of fit members through the conversion of redundant material into essential information; and the ability to enlarge or reduce the search space dynamically by varying the number of variables evaluated by the fitness function. The IRR GA provides a more biologically parallel representation that maintains a diverse population throughout the evolution process. In addition, the IRR provides the necessary flexibility to represent unstructured problem domains that do not have the explicit constraints required by fixed representations.

Algorithms↗

PubMed2000

MR imaging: its current and potential utility in the diagnosis and management of breast cancer.

The rapid evolution of the treatment of breast cancer has been paralleled by a similar rapid improvement in the imaging of breast cancer. High-resolution contrast-enhanced MR imaging of the breast has recently emerged as a sensitive instrument for the detection of breast cancer. The sensitivity of MR imaging makes it an excellent tool in specific clinical situations, such as the detection of local recurrence in patients who have received breast-conservation therapy. Furthermore, MR imaging of the breast has the potential to be a powerful aid in presurgical planning and to be a useful adjunct to mammography in selected patients. MR imaging, however, has a significant false-positive rate, is not readily available in all areas, and is more expensive than mammography and sonography. It also remains unclear if alterations of management plans based on MR imaging findings actually benefit affected patients. Therefore rigorous clinical trials are needed to define precisely the exact role that MR imaging should play in the diagnosis and management of breast cancer patients.

Breast↗

PubMed1987

Spindle coma in viral encephalitis.

Our patient's EEG evolved from the spindle coma pattern to normality in parallel with his clinical improvement. This clinical and EEG evolution has been described previously, and emphasizes the heterogeneity of the spindle pattern. The initial focal asymmetry implied focal cerebral abnormality, and was one of the clinical findings favoring HSV encephalitis in the absence of radiologic or pathologic support. The ability of partially-damaged cerebral cortex to express spindle activity is well-described with various cerebral lesions, as is the spindle coma pattern after intoxication. We are not aware of a previous report with HSV or other encephalitis, but an infectious etiology could be suspected in two patients of Hansotia et al. and is conceivable in the three comatose patients of Britt in whom no diagnosis could be established. In such cases, the pathophysiology of the spindle coma pattern is likely to involve an aberrant cortical response to normal reticular formation input and thalamic spindle pacemakers.

Adolescent↗

PubMed1984

[Are chorionic gonadotropin (HCG) and its alpha and beta subunits useful markers in non-trophoblastic tumors?].

HCG and its subunits alpha and beta are produced by trophoblastic cancers constituting an index of early detection and monitoring for these tumors. Unlike HCG-alpha, we can obtain specific HCG and HCG-beta assays with LH-neutralized antiserum. Many normal non-trophoblastic tissues exhibit a HCG-like immunoreactivity. All choriocarcinomatous testicular tumors produce HCG and HCG-beta. Half of all testicular teratomas produce HCG and its subunits while a third of all seminomas exhibit an HCG-like immunoreactivity, whether choriocarcinomatous component is present or not. Serum HCG levels are elevated in seminomas (5 to 22%) as well as teratomas '55 to 89%). Less than 15% of breast, digestive and lung cancers have increased serum levels of HCG and/or its 2 subunits. HCG is most often produced by undifferentiated lung cancers, hepatoblastomas and adrenal carcinomas. There is usually a parallel relation between these serum levels and the clinical evolution of the disease under chemotherapy. In breast cancer, these levels do not constitue a "prognosis index". HCG production by non-trophoblastic tumors can induce clinical symptoms such as precocious puberty and gynecomastia.

Breast Neoplasms↗

PubMedDate not supplied

[Hypoxemia and aging (author's transl)].

Hypoxemia during rest reveals the aging of the respiratory tract. The evolution curve of the PaO2 related to age is parallel to that of static elastic recoil pressure. This hypoxemia is moderate and without any serious functional consequences in a healthy subject. Abnormalities of the ventilation-perfusion ratio are the main causes. The increase of the anatomical dead space and the increase of the right-left shunt only play a moderate part. On the other hand the increase of closing volume seems the major factor. Thus the ventilation distribution becomes dependent on the amplitude of the tidal volume. The response of the aged subject to hypoxia is lessened for mechanical and neurological reasons explaining why a respiratory distress can appear rapidely and sometimes unexpectedly.

Adaptation, Physiological↗

PubMed1994

Ontogeny of the sensitivity of the somatotrophes to thyrotrophin releasing hormone (TRH) and growth hormone releasing factor (GRF) in the embryonic and posthatch chick.

The ontogeny of the in vitro growth hormone (GH) release after stimulation with thyrotrophin releasing hormone (TRH) or growth hormone releasing factor (GRF) has been studied in two strains of chickens during the last week of embryonic development and the first week posthatch. Fourteen-day-old embryos did not yet respond to any of the stimuli applied, while the amplitude of the GH response to the different stimuli increased gradually from 18-day-old embryos to 1-day-old chicks. The evolution of the responses to both stimulating agents was parallel in the two strains of chickens, but the amplitude of the response was always higher in the rapidly growing broiler strain compared to the slowly growing layer strain. The highest GH response was at all stages obtained with the highest dose of GRF (100 nM). At a lower dose (10 nM), however, TRH seemed to be a more effective GH releasing agent than GRF at the posthatch stages.

Animals↗

PubMed1994

The impact of health care reform on orthopaedic surgery in the United States and Canada.

Health care reform is not unique to the United States but reflects fundamental changes in attitudes to health care worldwide. Orthopaedic surgery must examine its role in the context of the overall health care delivery system, rather than in the narrow focus of our specialty, if we are to grow and continue to improve in the future. This lecture describes the evolution of the Canadian Health Care system and draws parallels to the current American environment from which valuable lessons may be learned. There are 5 reasons why health care costs more in the United States than in all other countries which are independent of the fact that the United States has the highest quality of medical care available in the world. These are excessive administrative costs and manpower; oversupply (and hence underutilization) of expensive technology and services; the "medicalization" of social costs; and the tremendous cost of medical liability and malpractice litigation. There are a number of steps that can be taken to enhance the role of orthopaedic surgery in health care without eliminating choice and impairing innovation, which are the critical elements in a high-quality health care system. The Canadian and American systems will be more similar in the future despite the different paths that we are taking in reform, and I believe we can look to the future with optimism and confidence if appropriate measures are taken to ensure that our contributions are effective and efficient.

Canada↗

PubMed1997

[Endo-coronary ultrasonography: significance of the images].

In addition to the assessment of the arterial lumen and coronary stenosis, endocoronary ultrasonography also provides information in vivo on the nature of atheromatous plaque. This study reports the preliminary correlations between the echographic appearances, the functional status of the patients and histological data of tissue obtained by directional atherectomy. The appearances of atheromatous infiltrations help distinguish stable forms of coronary disease with "hard", hyperreflective plaques, from acute forms with "soft" hyporeflective plaques. Ultrasonography confirms the clinico-pathological relationship of myocardial infarction and unstable angina with, in the acute forms, a similarity of the culprit plaques which appear vulnerable, hyporeflective and often complicated by the association of fissures and thrombus. The correlations with histological data are still incomplete. However, the "soft" nature of the plaque is an expression of its cellularity and lipid content whereas "hard" plaques correspond to increased fibrous tissue. These associations have no correlative values as yet. Nevertheless, they establish a parallelism which may eventually explain the functional variability and evolutivity of coronary artery disease. In the same way that visualisation of coronary stenosis led to the development of coronary artery surgery and later to angioplasty, observation of the plaque by ultrasonography should promote the development of pharmacological agents to treat the atheromatous lesions.

Adult↗

PubMed1993

Evolution of EF-hand calcium-modulated proteins. III. Exon sequences confirm most dendrograms based on protein sequences: calmodulin dendrograms show significant lack of parallelism.

In the first report in this series we presented dendrograms based on 152 individual proteins of the EF-hand family. In the second we used sequences from 228 proteins, containing 835 domains, and showed that eight of the 29 subfamilies are congruent and that the EF-hand domains of the remaining 21 subfamilies have diverse evolutionary histories. In this study we have computed dendrograms within and among the EF-hand subfamilies using the encoding DNA sequences. In most instances the dendrograms based on protein and on DNA sequences are very similar. Significant differences between protein and DNA trees for calmodulin remain unexplained. In our fourth report we evaluate the sequences and the distribution of introns within the EF-hand family and conclude that exon shuffling did not play a significant role in its evolution.

Animals↗

PubMed2005

Increased phospho-AKT is associated with loss of the androgen receptor during the progression of N-methyl-N-nitrosourea-induced prostate carcinogenesis in rats.

BACKGROUND: Characterization of molecular events during N-methyl-N-nitrosourea (MNU)-induced rat prostate carcinogenesis enhances the utility of this model for the preclinical assessment of preventive strategies. Androgen independence is typical of advanced human prostate cancer and may occur through multiple mechanisms including the loss of androgen receptor (AR) expression and the activation of alternative signaling pathways. METHODS: We examined the interrelationships between AR and p-AKT expression by immunohistochemical staining during MNU-androgen-induced prostate carcinogenesis in male Wistar-Unilever rats. Histone nuclear staining and image analysis was employed to assess parallel changes in chromatin and nuclear structure. RESULTS: The percentage of AR positive nuclei decreased (P < 0.01) as carcinogenesis progressed: hyperplasia (92%), atypical hyperplasia (92%), well-differentiated adenocarcinoma (57%), moderately-differentiated adenocarcinoma (19%), and poorly-differentiated adenocarcinoma (10%). Conversely, p-AKT staining increased significantly during carcinogenesis. Sparse staining was observed in normal tissues (0.2% of epithelial area) and hyperplastic lesions (0.1%), while expression increased significantly (P < 0.001) in atypical hyperplasia (7.6%), well-differentiated adenocarcinoma (16.7%), moderately-differentiated adenocarcinoma (19.6%), and poorly-differentiated adenocarcinoma (17.4%). In parallel, nuclear morphometry revealed increased nuclear size, greater irregularity, and lower DNA compactness as cancers became more poorly differentiated. CONCLUSIONS: In the MNU model, the progressive evolution of dominant tumor cell populations showing an increase in p-AKT in parallel with a decline in AR staining suggests that activation of AKT signaling may be one of several mechanisms contributing to androgen insensitivity during prostate cancer progression. Our observations mimic findings suggested by human studies and support the relevance of the MNU model in preclinical studies of preventive strategies.

Alkylating Agents↗

PubMed1987

Animal models for the evolution of thrombotic disease.

Naturally occurring hemorrhagic and thrombotic diseases of animals closely parallel their human counterparts. While such models may be particularly useful in studying the pathogenesis of human disease, it is usually more realistic to depend upon experimentally induced disease models. The species selected for use is therefore of major importance in providing meaningful extrapolation to humans, as are the experimental design and type of procedure (in vitro, ex vivo, in vivo). Regardless of the test system used when in vitro procedures are employed, these must be translated eventually to the in vivo situation. Information about the normal aging process of different species is important here and should influence selection of the species and test system. The ideal situation may not be feasible or pertain because of cost, availability, size, and investigator familiarity, or lack thereof, with the most suitable species or model.

Animals↗

PubMed2006

The eloquent ape: genes, brains and the evolution of language.

The human capacity to acquire complex language seems to be without parallel in the natural world. The origins of this remarkable trait have long resisted adequate explanation, but advances in fields that range from molecular genetics to cognitive neuroscience offer new promise. Here we synthesize recent developments in linguistics, psychology and neuroimaging with progress in comparative genomics, gene-expression profiling and studies of developmental disorders. We argue that language should be viewed not as a wholesale innovation, but as a complex reconfiguration of ancestral systems that have been adapted in evolutionarily novel ways.

Animal Communication↗

PubMed1996

Pseudohomothallism and evolution of the mating-type chromosome in Neurospora tetrasperma.

Ascospores of Neurospora tetrasperma normally contain nuclei of both mating-type idiomorphs (a and A), resulting in self-fertile heterokaryons (a type of sexual reproduction termed pseudohomothallism). Occasional homokaryotic self-sterile strains (either a or A) behave as heterothallics and, in principle, provide N. tetrasperma with a means for facultative outcrossing. This study was conceived as an investigation of the population biology of N. tetrasperma to assess levels of intrastrain heterokaryosis (heterozygosity). The unexpected result was that the mating-type chromosome and autosomes exhibited very different patterns of evolution, apparently because of suppressed recombination between mating-type chromosomes. Analysis of sequences on the mating-type chromosomes of wild-collected self-fertile strains revealed high levels of genetic variability between sibling A and a nuclei. In contrast, sequences on autosomes of sibling A and a nuclei exhibited nearly complete homogeneity. Conservation of distinct haplotype combinations on A and a mating-type chromosomes in strains from diverse locations further suggested an absence of recombination over substantial periods of evolutionary time. The suppression of recombination on the N. tetrasperma mating-type chromosome, expected to ensure a high frequency of self fertility, presents an interesting parallel with, and possible model for studying aspects of, the evolution of mammalian sex chromosomes.

Chromosome Mapping↗

PubMed2004

Evaluating commercial weight loss programmes: an evolution in outcomes research.

The increasing prevalence of obesity has been mirrored by a parallel increase in the number of commercial weight loss programmes. Research evaluating these programmes is meagre, however, compared to the numbers treated. Reluctance of commercial weight loss programmes to meaningfully evaluate their weight loss efficacy may arise from fear that competitors will use the results against them. Evaluation of commercial weight loss programmes usually progresses from testimonials, often by famous people who were successful, to uncontrolled studies of past participants evaluated either by the programme itself or by an outside entity. The gold standard, however, is a scientifically rigorous, controlled study of the programme conducted by an independent entity. Such a study, published in a peer-reviewed journal, can gain credibility for a programme, as it did with Slim Fast, if the results are positive, or herald the end of the programme, as it was with Simeons human chorionic gonadotropin injection clinics. This review of the evolution of the evaluation process of commercial weight loss programmes leads us to conclude that consumers are likely to demand greater scientific rigour in the future, a change that will favour informed choice and discourage the practice of unrealistic advertising that raises false hopes.

Diet Fads↗

PubMed1979

In vitro granulopoiesis in oligoblastic leukaemia: prognostic value, characterization and serial cloning of bone marrow colony and cluster forming cells in agar culture.

The colony and cluster forming capacity of bone marrow cells (BM CFC and CluFC) in agar culture, was studied from 20 oligoblastic patients. 13 patients had a leukemic growth pattern and 12 of these died within one year after diagnosis. 7 patients had no leukemic growth and 4 are alive 16 to 90 months after diagnosis. Both the determination of the proportion of abnormally light buoyant density of CFC and CluFC and the study of their suiciding index were used to characterize more precisely the leukemic or nonleukemic status of patients. Because of the small number of patients involved in the later preliminary study, the prognostic significance cannot be valuated. Serial studies of individual patients showed different types of evolution in the growth pattern of BM CFC and CluFC. Either the increase of BM CFC and CluFC paralleled that of the myeloblasts, or there was a change in the growth pattern before AML transformation suggesting clonal evolution.

Aged↗

PubMed2006

[The Swiss archaeologist Otto Hauser. His skeletal findings and hypothesis on the evolution of man and his extensive activities in the development of prehistorical research and evolution].

New investigations on Otto Hauser's skeleton findings and the excavations of this Swiss citizen in Southwest France from 1906 until 1914 placed the activities of this archaeologist again in the focus of scientific and public interest. This paper describes life and oeuvre of Otto Hauser and discusses the importance of the skeletons found by him and Hermann Klaatsch as well as the consequences of their discovery. The efforts of Otto Hauser to publish his discoveries, to present and spread his view concerning the evolution of man were remarkably manifold as well as the parallels between ancient man and contemporary ethnic groups living on a low technological level drawn by him and to wake and to promote the interest in prehistory. Many books, brochures, articles and public lectures contributed to this intention as well as co-operation with local historians and scientists of other disciplines, and also many films, teaching and illustrative materials. The scientific collection of the authors of this article comprises more than 6,500 written documents and photos.

Archaeology↗

PubMed2005

Evolution of the pregnane x receptor: adaptation to cross-species differences in biliary bile salts.

The pregnane X receptor (PXR) regulates the metabolism and elimination of bile salts, steroids, and xenobiotics. The sequence of the PXR ligand-binding domain diverges extensively between different animals, suggesting interspecies differences in ligands. Of the endogenous ligands known to activate PXR, biliary bile salts vary the most across vertebrate species, ranging from 27-carbon (C27) bile alcohol sulfates (early fish, amphibians) to C24 bile acids (birds, mammals). Using a luciferase-based reporter assay, human PXR was activated by a wide variety of bile salts. In contrast, zebrafish PXR was activated efficiently only by cyprinol sulfate, the major zebrafish bile salt, but not by recent bile acids. Chicken, mouse, rat, and rabbit PXRs were all activated by species-specific bile acids and by early fish bile alcohol sulfates. In addition, phylogenetic analysis using maximum likelihood demonstrated evidence for nonneutral evolution of the PXR ligand-binding domain. PXR activation by bile salts has expanded from narrow specificity for C27 bile alcohol sulfates (early fish) to a broader specificity for recent bile acids (birds, mammals). PXR specificity for bile salts has thus paralleled the increasing complexity of the bile salt synthetic pathway during vertebrate evolution, an unusual example of ligand-receptor coevolution in the nuclear hormone receptor superfamily.

Animals↗

PubMedDate not supplied

[Benign paroxysmal positional vertigo: clinical aspects and medico-legal considerations].

Benign paroxysmal positional vertigo (BPPV) is quite frequently found as an otological consequence of cranial traumas; thus leading to medico-legal implications. An attempt has herewith been made to evaluate these implications on the basis of data available. Therefore, 158 patients suffering from BPPV were examined between 1984-1986. Of these 23% of the total were post-traumatic forms (of medico-legal interest). Among patients suffering from post-traumatic vestibular disturbances in the broad sense, the incidence of BPPV proved to be greater in the ages ranging from 50 to 70. In those under 30 years of age BPPV was hardly ever present (5% of the total) although when it was its origin was always post-traumatic. The temporal evolution of paroxysmal positional vertigo, which tends to spontaneously disappear, is paralleled in BPPV patients whether it is of post-traumatic origin or not. On the other hand, the subjective sensation of positional vertigo takes longer to clear up in post-traumatic BPPV patients, most likely due to factors stemming from the so-called "compensation syndrome". Any medico-legal evaluation of BPPV must, therefore, take into account its natural favorable evolution. This makes it necessary to examine the patient several times over a period of at least six months from the moment of trauma. In medico-legal terms, the features of BPPV (i.e. position setting it off, duration of vertigo, frequency with which it appears when that position is assumed, presence and duration of the positional nystagmus) lead to inability to work in from 2 to 10% of the cases.

Adolescent↗