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Results for “Continuous Evolution”

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PubMed1982

Endolymphatic stromal myosis. Surgical and hormonal treatment of extensive abdominal recurrence 20 years after hysterectomy.

This report describes the clinicopathologic features of a 49-year-old woman who was reoperated on for bulky abdominal metastases 20 years after hysterectomy for endometrial stromal myosis (ESM). The levels of estrogen (ER) and progesterone (PR) receptors measured in the resected tumorous tissue amounted to 48.3 and 71.4 femtomoles (fmol)/mg cytosol protein, respectively. After medroxyprogesterone acetate (Depo-Provera; Upjohn) treatment of 16 months duration, the unresected pelvic tumor mass compressing the bladder and the left ureter had decreased in volume and hydroureteronephrosis had regressed. The efficacy of the therapy was monitored by computed tomography. Two years and nine months after surgery, the evolution of the tumor seems well-controlled by continuous progestin therapy and the patient is living without symptoms.

Abdominal Neoplasms↗

PubMed2002

Batch gravitational sedimentation of slurries.

We investigated the batch settling behavior of the kaolin slurry and the UK ball clay slurry at various initial solids fractions (phi(0)s) using a computerized axial tomography scanner (CATSCAN). The spatio-temporal evolutions of solids fractions in the consolidating sediments were continuously monitored. Since the interface between the sediment and the supernatant of the investigated slurries was blurred, an averaging procedure was employed to estimate their null-stress solids fractions (phi(g)s). Besides the rather slow settling for the high-phi(0) slurries, the basic settling characteristics resemble each other regardless of whether phi(0)>phi(g) or vice versa. The above-mentioned experimental data reveal that the investigated slurries are neither purely elastic nor purely plastic in rheological behavior. On contrary to most model works a blurred supernatant-sediment interface makes difficulty in the gel point determination. During initial settling the high-phi(0) slurries clearly exhibit a finite yield stress to resist deformation. That is, the slurries are plastic fluids. However, the network structure in the slurries deteriorates gradually in the subsequent settling stage while the final, equilibrated sediment reveals a continuous distribution in solids fraction. Restated, the final sediment possesses as a purely elastic characteristic. The model parameters of theory by Buscall and White were regressed by the dynamic consolidating sediment data, while those by Tiller and Leu were obtained using the final equilibrated sediment data. Calculations from both models reveal that ball clay slurry is more compressible than is the kaolin slurry. The high-phi(S0) slurry would yield the less compressible sediment.

Journal Article↗

PubMedDate not supplied

Principles of surgical technique in the treatment of carcinoma of the large bowel.

The principles of surgical technique for the operative management of colon cancer are described. With the background of the evolution of anastomotic alternatives, the methods for reestablishing intestinal continuity and the approach to the treatment of complicated presentations of colonic cancer are reviewed. While one may construe this paper to have a certain author bias, I have tried to present diverse options where pertinent, but there should be little question as to where my opinion lies.

Anastomosis, Surgical↗

PubMed1986

Comparative rates of esterification of 5'-AMP with hydrophobic amino acids: relevance to the genetic-code assignments.

We have continued our program aimed at understanding the origin and evolution of the genetic code and the process of protein synthesis by comparing the rates of esterification of 5'-AMP by a series of hydrophobic N-acetylamino acids. The reaction clearly shows differences in reaction rate (AcPhe greater than AcLeu greater than AcVal greater than AcIle) among the amino acids having A as middle letter of their anticodons. However, there were no significant differences in reaction rate between AcLeu, AcNorleu, and Ac-alpha-aminobutyric acid, and AcGly reacted faster than all of these and AcPhe. Consequently, this simple reaction with AMP can distinguish only among those amino acids that actually have A as the middle anticodonic nucleotide. The relevance of these studies to the origins of the process of protein synthesis and of the genetic code is discussed in conjunction with results from other studies of a similar nature.

Acetylation↗

PubMed2004

Numerical model to predict the long-term mechanical stability of cementless orthopaedic implants.

The objective of this research was to develop a purely biomechanical model, intended to predict the long-term secondary stability of the implant starting from the biomechanical stability immediately after the operation. A continuous rule-based adaptation scheme was formulated as a dynamic system, and the work verified if such a model produced unique and clinically meaningful solutions. It also investigated whether this continuous model provided results comparable with those of a simpler, discrete-states model used in a previous study. The proposed model showed stable convergence behaviour with all investigated initial conditions, with oscillatory behaviour limited to the first steps of the simulation. The results obtained with the wide range of initial conditions support the hypothesis of the existence and uniqueness of the solution for all initial conditions. The differences between the continuous model and the simpler and more efficient finite-states model were found to be extremely modest (less than 4% over the predicted bonded area). Because of these minimal differences, the use of the much faster finite-states model is recommended to investigate asymptotic conditions, and the continuous model described should be used to investigate the evolution over time of the adaptive process.

Adaptation, Physiological↗

PubMed2001

Immunopathogenesis of the multiple sclerosis lesion.

Multiple sclerosis (MS) is thought to be an autoimmune disease with a chronic inflammatory response directed against central nervous system (CNS) myelin antigens. Immunologic studies indicate that autoreactive CD4+ lymphocytes migrate into the CNS causing blood brain barrier (BBB) disruption, an initial event in the evolution of the MS lesion. Subsequent antigen recognition within the CNS initiates inflammatory responses that, through the multiple effector mechanisms, lead to demyelination. Magnetic resonance imaging (MRI) studies provide new insights into the evolution of the MS lesion, revealing an active and continuous pathologic process that is not only localized to focal lesions, but also diffusely affects normal appearing white matter (NAWM). Standard T2-weighted images are exquisitely sensitive, showing changes due to inflammation, edema, demyelination, and axonal loss, but because of the lack of pathologic specificity, they only moderately correlate with the clinical parameters. New MRI techniques, including magnetic resonance spectroscopy, magnetization transfer, and diffusion imaging, provide a better measure of axonal loss and demyelination, the most clinically relevant components of MS lesions. Hopefully, they will enable us to more accurately monitor disease activity and evaluate the effects of new therapies on the progression of the disease.

Antigen Presentation↗

PubMed1979

[Effect of cooling and electrical stimulation of nuclei of raphe system on states of alertness in cat].

In cats prepared in a 'semi-chronic' manner (spinal cord transected, brachial plexus sectioned bilaterally) all states of alertness are present; their quantitative evolution is characterized by an immediate postoperative period with continuous wakefulness and a secondary period of recovery of the states of sleep, which are then maintained. In such a preparation, localized moderate cooling (+10 degrees C) of the nucleus raphe dorsalis induces slow wave sleep and paradoxical sleep; the same type of cooling of the nucleus raphe magnus induces wakefulness; however, the electrical stimulation of these two nuclei always induces wakefulness. Cooling of the nuclei raphe centralis or pontis suppresses only the 'ponto-geniculo-occipital' (PGO) waves. Colling of the nuclei raphe obscurus and pallidus induces wakedfulness, but stage I of slow wave sleep may occur. Treatment with p-chlorophenylalanine (PCPA) before making the semi-chronic preparation produces the classical syndrome characterized by cortical activation and continuous discharge of PGO waves; in this case cooling of the nucleus raphe dorsalis no longer induces slow wave sleep but only paradoxical sleep; after injection of DL-5-HTP, slow wave sleep is obtained again through cooling; this effect diminishes progressively.

5-Hydroxytryptophan↗

PubMed1990

Chronic persistent hepatitis type B can be a progressive disease when associated with sustained virus replication.

In 44 hepatitis B virus (HBV) carriers with chronic persistent hepatitis (CPH), serial liver biopsies were available. At presentation 38 patients had HBV-DNA in their serum including 31 HBeAg positive and seven anti-HBe positive cases. The remaining six patients were anti-HBe positive and HBV-DNA negative. During a mean histologic follow-up of 4.2 years, 12 (32%) of the 38 HBV-DNA positive patients progressed to chronic active hepatitis (six cases) or to active cirrhosis (six cases), while 26 patients showed either unchanged features of CPH (21 cases), or histologic improvement to normal liver (five cases). Persistence of HBV-DNA in serum, independently of HBeAg/anti-HBe events, was significantly (p less than 0.01) associated with deterioration of liver disease, while termination of HBV replication correlated significantly (p less than 0.05) with spontaneous biochemical remission and with unchanged or improved histology. None of the six anti-HBe positive patients without serologic markers of hepatitis B virus replication showed histologic deterioration. These findings indicate that continuing HBV replication is a marker which predicts unfavourable evolution of chronic persistent hepatitis and frequent transition to chronic active hepatitis or cirrhosis.

Adolescent↗

PubMed1991

Vertical transmission of helminths: Hypobiosis and amphiparatenesis.

Vertical transmission has evolved in at least five lines of helminths and involves prenatal or, more commonly, transmammary pathways to the offspring. In this article, vertical transmission, hypobiosis and paratenesis are combined in a strategy for transmission called amphiparatenesis. Although many believe that vertical transmission of parasites is rare, Wesley Shoop suggests that it is not only significant in the evolution of certain helminths but it may have been one of the pivotal adaptations in the evolution of the eukaryotes and is essential in their continued existence.

Journal Article↗

PubMed2006

[Evaluation of the Chêneau brace in adolescent idiopathic scoliosis].

OBJECTIVE: We aimed to evaluate the Chêneau brace in the orthopedic treatment of adolescent idiopathic scoliosis to better determine the indications under which it could be prescribed. MATERIALS AND METHODS: This was a retrospective study including 63 patients treated by Chêneau brace for adolescent idiopathic scoliosis between 1997 and 2006. The Cobb angles of the curves in the frontal and sagittal planes as well as rotations and rib hump were measured at the beginning of treatment, with the brace, at the end of treatment and 2 years after discontinuing the brace. A variation of+/-10 degrees in angle was selected to judge the results. RESULTS: At the end of the treatment, 25.4% of the curves were improved and 60.3% stabilized, with 14.3% aggravated; 5 patients (7.9%) required surgery. At 2 years, the reduction in angle was 1.8 degrees, on average. The best results were obtained for the lumbar and dorsolumbar curves. A significant improvement was noted for the dorsal curves; the major double curves are not as accessible to the treatment. For curves whose initial angle was less than 30 degrees , an initial reduction of higher than 50% with the brace presented the best improvement at the end of the follow-up. We note a significant reduction of the rib hump but not accompanied by a reduction of rotation. Finally, we note a deleterious effect in the sagittal curves, with a slight flatness of the spinal profile. CONCLUSION: The continuous wearing of the Chêneau brace can stabilize the evolution of adolescent idiopathic scoliosis, apart from the forms with major double curves, which are not as accessible to the treatment. However, the improvement comes at the price of a slight flatness of the curves of the spine in the sagittal plane. The loss of the correction after discontinuing the brace is minor. We emphasize, therefore, the necessity to monitor the sagittal aspect of the spine as well as the possibility of early treatment, strict surveillance and prolonged follow-up.

Adolescent↗

PubMed2006

New opportunities revealed by biotechnological explorations of extremophiles.

Over the past few decades the extremes at which life thrives has continued to challenge our understanding of biochemistry, biology and evolution. As more new extremophiles are brought into laboratory culture, they have provided a multitude of potential applications for biotechnology. More recently, innovative culturing approaches, environmental genome sequencing and whole genome sequencing have provided new opportunities for the biotechnological exploration of extremophiles.

Archaea↗

PubMed2004

Functional and molecular evaluation of lymphocytes.

The laboratory plays a central role in the evaluation of immune function and is critical in the diagnosis and treatment of immune deficiencies. The range of options available to evaluate lymphocyte function has expanded dramatically as our understanding of the immune system has expanded. As the choices of laboratory tests increase, so also does the need to choose testing in such a way as to appropriately direct the evaluation. Typically, this approach involves starting with screening tests and, on the basis of the results of these tests, deciding whether more sophisticated and expensive testing is warranted. The remarkable developments over the past decade leading to the identification of numerous gene defects underlying a variety of immune deficiencies has moved mutation analysis into the realm of the clinical laboratory. This information could be indispensable for immune deficiency diagnosis, prenatal screening, carrier detection, and family counseling. In this review a sequential approach to evaluating lymphocyte function is presented, starting with readily available screening tests and followed by more complex in vitro testing, including the application of newer assays. The various approaches are presented from the perspective of appropriate use and information garnered, whereas actual details of test procedures are not discussed but are referenced. The evolution of immune function testing suggests that it will continue to develop, and future assays are likely to provide even more insight into specific aspects of the immune response and be linked to immune deficiencies not yet defined.

Animals↗

PubMedDate not supplied

Modeling the isolated cardiac myocyte.

Computer modeling of cardiac myocytes has flourished in recent years. Models have evolved from mathematical descriptions of ionic channels alone to more sophisticated formulations that include calcium transport mechanisms, ATP production and metabolic pathways. The increased complexity is fueled by the new data available in the field. The continuous production of experimental data has led to the evolution of increasingly refined descriptions of the phenomena by modelers. Integrating the numerous systems involved in cardiac myocyte homeostasis makes the use of computer models necessary due to the unreliability of intuitive approaches. However the complexity of the model should not imply a cumbersome operation of the program. As with any tool, computer models have to be easy to operate or their strength will be diminished and potential users will not benefit fully from them. The contribution of the computer modeler to their respective biological fields will be more successful and enduring if modelers devote sufficient time to implement their equations into a model with user-friendly characteristics.

Action Potentials↗

PubMed2002

Involvement of the mural thrombus as a site of protease release and activation in human aortic aneurysms.

Acquired abdominal aortic aneurysms are usually associated with a mural thrombus through which blood continues to flow. Some early data suggest that aneurysmal evolution correlates with the biological activity of the thrombus. Our hypothesis was therefore that the thrombus could adsorb blood components and store, release, and participate in the activation of proteases involved in aneurysmal evolution. For this purpose, we have explored both the metalloproteinase and fibrinolytic systems in the thrombus and the wall of human aneurysms. We have first investigated blood clot formation and lysis in vitro. Spontaneous clotting induces a release of promatrix metalloproteinase (pro-MMP)-9 into the serum that was fourfold higher than in paired control plasma (P < 0.001). Fibrinolysis progressively released more MMP-9 in a time-dependent manner (P < 0.01). After selective isolation, we demonstrated that polymorphonuclear leukocytes are the main source of MMP-9 release during clot formation. Protease content was then analyzed in 35 mural thrombi and walls of human abdominal aortic aneurysms sampled during surgical repair. In 15 aneurysms, the liquid phase at the interface between the thrombus and the wall was sampled separately. Both thrombus and wall contained MMP-2 and MMP-9 but the ratio MMP-9/MMP-2 was higher in the thrombus than in the wall. The liquid interface also contained active MMP-9. Immunohistochemistry of the thrombus confirmed these findings, showing the presence of polymorphonuclear leukocytes at the luminal pole of the thrombus, co-localizing with MMP-9 storage. In contrast, MMP-3 and MMP-7 were only present in the aneurysmal wall. Plasminogen was present in the mural thrombus but plasmin activity was present in both thrombus and wall. In the liquid interface, plasmin-alpha(2)-anti-plasmin complexes were detected demonstrating in vivo the activation of plasminogen. In contrast, u-PA and t-PA were detectable only in the wall, suggesting that plasminogen present in the thrombus could be activated by factors secreted by the arterial wall. This was demonstrated in vitro, in which co-incubation of thrombus and wall extracts generated plasmin in the presence of a fibrin matrix and activated MMPs. In conclusion, our study strongly suggests that the mural thrombus, by trapping polymorphonuclear leukocytes and adsorbing plasma components could act as a source of proteases in aneurysms that may play a critical role in enlargement and rupture.

Abdominal Wall↗

PubMed2000

Malignant hematopoietic cell lines: in vitro models for the study of myelodysplastic syndromes.

The myelodysplastic syndromes (MDS) are clonal myeloid disorders characterized by bone marrow cell dysplasia and ineffective hematopoiesis leading to peripheral refractory cytopenias. The course of the disease ranges from a chronic status with progressively impaired hematopoiesis to rapid evolution to acute myeloid leukemia (AML). A panel of continuous malignant hematopoietic cell lines has been established from the whole spectrum of MDS variants and also from the different stages of the diseases, namely from the MDS phase or the overt leukemia post-MDS phase. Ten cell lines were derived from the various MDS subtypes; 17 cell lines were established from patients with leukemia (mainly AML) post-MDS. While most cell lines display myelocytic, monocytic or erythroid features, some cell lines carry lymphoid characteristics (precursor B-cell, B-cell, or T-cell), With regard to these lymphoid MDS-derived cell lines, more detailed authentication (prove of derivation from the assumed patient) and verification (prove of the malignant nature of the cell line and derivation from the assumed neoplastic cells) are required to validate the cell lines as true in vitro representatives of MDS and to exclude any cross-contamination with other cells or immortalization of normal bystander cells. On the other hand, lymphoid MDS-derived cell lines may attest to the clonal nature of MDS which may afflict progenitor cells giving rise to lymphoid or myelomonocytoid cells. Many of the MDS-derived cell lines carry cytogenetic and molecular genetic abnormalities typically associated with MDS: gain or loss of all or parts of chromosomes 5, 7, 8 and 20 (-5/5q-, -7/7q-, + 8, 20q-); alterations of oncogenes and tumor suppressor genes (IRF-1, p15, p16, p53, RAS, RB). In summary, the present panel of cell lines provides continuously growing cells and thus unlimited cell material for use as in vitro paradigms covering the whole spectrum of MDS-related hematopoetic malignancies. Properly authenticated and verified MDS-derived cell lines which should be made freely available will represent important research tools for the study of MDS biology.

Adult↗

PubMed2003

Optimal therapy for oesophageal cancer.

Oesophageal carcinoma is one of the commonest cancers in the world and has an increasing incidence in Western civilisation. As the epidemiology of the disease has changed so too has our treatment strategies. The present standard of care is surgery but this is associated with disappointing survival figures. The role of chemotherapy and radiation is now established in inoperable disease. How best to deliver these modes of therapy has yet to be defined. Extrapolation of data from previous trials is difficult as these trials have many deficiencies and do not account for recent advances in therapeutics or techniques of delivery. The role of chemo-radiotherapy in operable disease is even more controversial. A number of prospective randomised trials of trimodality therapy versus surgery alone suggests a benefit for multimodal therapy. These trials also reveal evidence to support the use of chemo-radiotherapy alone in a subset of patients with resectable disease. The appropriate application of these varied therapeutic interventions remains unanswered. Further progress in diagnostic techniques and predictive markers may allow us to stratify patients into different treatment groups. Continued investigation is required to keep pace with the evolution of oesophageal cancer and its therapy. This will facilitate a better understanding of the disease and optimise the treatment offered to patients.

Adenocarcinoma↗

PubMed1998

Improving hydrolases for organic synthesis.

Improving hydrolases by site-directed mutagenesis continues to be important, but an alternative method - directed evolution - also gains favor. Directed evolution combines random mutagenesis with screening or selection for the desired property. Directed evolution is especially useful for cases like solvent tolerance or thermostability where current theories are inadequate to predict which structural changes will give improvement. Researchers have also recently made significant progress on several practical problems: how to maintain the high activity of proteases and lipases in nonpolar organic solvents, how to resolve amines, and how to efficiently recycle the unwanted enantiomer in kinetic resolutions. Besides the lipases and proteases, researchers are also developing new hydrolases, notably dehalogenases and epoxide hydrolases.

Directed Molecular Evolution↗

PubMed1999

Instantaneous EEG coherence analysis during the Stroop task.

OBJECTIVE: In the present study the Stroop effect is analyzed by means of EEG coherence analysis in addition to traditional analysis of behavioral data (reaction time) and ERP analysis. Data from 10 normal subjects are examined. METHODS: In particular, a special dynamic approach for a continuous coherence estimation is applied to investigate the procedural evolution of functional cortical relationships during the Stroop task. RESULTS: The frequency band of 13-20 Hz is found to be sensitive to the discrimination between the congruent and the incongruent task conditions on the basis of instantaneous coherence analysis. The magnitude of coherence values within the time interval of late potentials and the maximal coherence values are used to assess the strength of interaction between distinct areas of the cortex. Higher coherences are observed within the left frontal and left parietal areas, as well as between them for the incongruent situation in comparison with the congruent situation. Furthermore, the time-points of maximal coherence allows a procedural discrimination between both situations. The peak synchrony described by the time-points of maximal coherence correlates strongly with the reaction times mainly within the frontal area and between fronto-parietal areas in the incongruent case, whereas this correlation is restricted to the right hemisphere in the congruent case.

Adult↗