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PubMed2006

Diurnal variation of the delta 13C of pine needle respired CO2 evolved in darkness.

The delta 13C of pine needle CO2 evolved in darkness (delta 13Cr) for slash pine trees (Pinus elliottii) was determined by placing recently collected pine needles in darkness and collecting respired CO2 over a short time period (<15 min). Delta 13Cr measurements were made over several 24 h periods to test the hypothesis that significant variation in delta 13Cr would be observed during a diurnal cycle. The delta 13Cr measurements from the 24 h time series trials showed a consistent midday 13C-enrichment (5-10 per thousand) relative to bulk biomass. The delta 13Cr values became more 13C-depleted at night and following shading, and approached bulk-biomass delta 13C values by dawn. The effect of night-time respired 13C-enriched CO2 on the delta 13C value of the remaining assimilate is shown to be minimal (13C depleted by 0.22 per thousand) under field conditions for P. elliottii needles.

Carbon Dioxide↗
PubMed1995

Carotene desaturation is linked to a respiratory redox pathway in Narcissus pseudonarcissus chromoplast membranes. Involvement of a 23-kDa oxygen-evolving-complex-like protein.

The enzymic activity of phytoene desaturase in Narcissus pseudonarcissus chromoplast membranes depends in an essential way on the redox state of its environment. Here, the main redox-active components are quinones and tocopherols. Quinones (oxidized) act as intermediate electron acceptors in the desaturation reaction, as can be shown in reduced, hydroquinone-rich membranes. However, their complete oxidation by ferricyanide treatment of membranes leads to inhibition of the desaturation activity and, under these conditions, hydroquinones are required for reactivation. Using redox titrations, it is shown here that the optimal activity lies in the range of the midpoint potential of the plastoquinone/plastohydroquinone redox couple. For the adjustment of redox states of the redox-active lipid components in (photosynthetically inactive) chromoplasts, NADPH and oxygen are involved, the latter acting as a terminal acceptor. This results in a respiratory redox pathway in chromoplast membranes which is described here, to our knowledge, for the first time. Since phytoene desaturation responds to the redox state of quinones, which is adjusted by the respiratory redox pathway, the two reactions must be regarded as being mechanistically linked. The first protein component involved in the respiratory pathway which we have investigated molecularly is a 43-kDa NAD(P)H:quinone oxidoreductase, which is organized as a homodimer (23 +/- 3 kDa/subunit) and apparently possesses a manganese redox center. Internal protein microsequencing and cloning of the corresponding cDNA revealed a high degree of similarity to the 23-kDa protein of the oxygen-evolving complex of photosystem II, but no information about the N-terminal organization of the oxidoreductase could be obtained. During flower development, the steady-state concentration of the corresponding mRNA is up-regulated, indicating a specific function of the gene product in chlorophyll-free chromoplasts.

Amino Acid Sequence↗
PubMed1996

The cloning of a rapidly evolving seminal-vesicle-transcribed gene encoding the major clot-forming protein of mouse semen.

Approximately 30 kb of the mouse genome, containing the gene for a major seminal vesicle transcript, has been cloned. The gene was identified by the similarity to members of a family with rapidly evolving genes that includes the gene encoding the major clot protein in rat semen, SVS II, and the human semenogelin genes. The nucleotide sequence of 16.9 kb was determined; this sequence encompasses the gene of 2215 bp plus 9-kb and 5.6-kb regions flanking the 5' and 3' ends of the gene. The transcription unit is divided into three exons, of which the first encodes the signal peptide, the second the secreted protein, while the third exon contains 3'-nontranslated nucleotides only. The transcript encodes a protein of 375 amino acid residues, including a signal peptide of 22 residues. The secreted polypeptide is a protein of Mr 38442 and is similar in sequence but smaller than the major clot-forming protein of rat semen, SVS II. It is highly charged at pH 7 and it has an isoelectric point of 10.68. The central part of the protein consists of tandem repeats that might serve as a substrate for transglutaminase.

Amino Acid Sequence↗
PubMed2004

Structural characterization of photosystem II complex from red alga Porphyridium cruentum retaining extrinsic subunits of the oxygen-evolving complex.

The structure of photosystem II (PSII) complex isolated from thylakoid membranes of the red alga Porphyridium cruentum was investigated using electron microscopy followed by single particle image analysis. The dimeric complexes observed contain all major PSII subunits (CP47, CP43, D1 and D2 proteins) as well as the extrinsic proteins (33 kDa, 12 kDa and the cytochrome c(550)) of the oxygen-evolving complex (OEC) of PSII, encoded by the psbO, psbU and psbV genes, respectively. The single particle analysis of the top-view projections revealed the PSII complex to have maximal dimensions of 22 x 15 nm. The analysis of the side-view projections shows a maximal thickness of the PSII complex of about 9 nm including the densities on the lumenal surface that has been attributed to the proteins of the OEC complex. These results clearly demonstrate that the red algal PSII complex is structurally very similar to that of cyanobacteria and to the PSII core complex of higher plants. In addition, the arrangement of the OEC proteins on the lumenal surface of the PSII complex is consistent to that obtained by X-ray crystallography of cyanobacterial PSII.

Algal Proteins↗
PubMed1979

A model of imprinting evolved from neurophysiological concepts.

The imprinting process is described by a model evolved from physiological data. For the case of sexual imprinting in zebra finches a second sensitive phase, occurring at sexual maturity, is considered. The first sensitive phase is not restricted exclusively to the imprinting of sexual objects. Properties of the model allow for the explanation of apparent reversibility of imprinting. The same physiological mechanisms involved in the organization of simple neuronal connections are assumed to operate in the highly complex networks associated with imprinting phenomena.

Animals↗
PubMed1992

Laparoscopy-guided percutaneous cholecystolithotomy: an evolving technique.

Gall-bladder conservation therapy has been evolving during the past decade. Popular techniques of conservative therapy are extracorporeal shock wave lithotripsy (ESWL) and medical dissolution therapy. The limitations of these procedures have prompted a search for alternative techniques, particularly in relation to percutaneous stone extraction. The cases of four patients with symptomatic gallstones who underwent percutaneous cholecystolithotomy under laparoscopic guidance are reported. The gall-bladder was punctured with a long needle and the tract dilated so that a nephroscope could be introduced. Three cases required stone fragmentation by an ultrasonic lithotripter before removal. Postoperative recovery was uneventful in all cases.

Adult↗
PubMed1992

Accuracy of a portable interpretive ECG machine in diagnosis of acute evolving myocardial infarction.

From a study of 526 patients having automatic ECG analysis, criteria were established which diagnosed acute evolving Q wave myocardial infarction with 71% sensitivity and 98% specificity. Specificity was 100% when patients with known previous Q wave infarction were excluded. In pre-hospital practice the high sensitivity and specificity were maintained. This method appears appropriate, when other criteria are met, for paramedic-initiated pre-hospital thrombolysis with remote supervision of a cardiologist by telephone.

Adult↗
PubMed2004

Out of fertile muck: the evolving narrative of nursing.

The ongoing debate over the appropriateness of embracing multiple research traditions in nursing is discussed, and the impacts of that debate on the development of nursing knowledge and the nature and structure of the discipline are explored. It is asserted that this previously healthy debate has become stalled between extreme positions of unbounded pluralism and critical exclusivism. The author suggests that one possible solution may lie in connecting the elements of human living, human healing, and human wholeness in an evolving narrative that crosses paradigmatic and theoretic boundaries, and reflects the unique meanings revealed in nursing practice and scholarship.

Humans↗
PubMed2005

Ofuji papuloerythroderma evolving to cutaneous T-cell lymphoma.

Ofuji papuloerythroderma is an uncommon entity of unknown aetiology, characterized by a pruritic eruption of widespread, red-brown, flat papules that leads to spare skin folds. A number of cases have been described associated with tumour pathology, mainly cutaneous T-cell lymphomas. We report a new case of Ofuji papuloerythroderma evolving to cutaneous T-cell lymphoma in an 85-year-old woman who had been previously diagnosed with papuloerythroderma 7 years previously.

Aged↗
PubMed2006

Evolving trends in infective endocarditis.

Infective endocarditis is a microbial infection of the endocardial surface and, despite improvements in diagnostic accuracy, medical therapy and surgical techniques, mortality remains high. This review focuses on changes in epidemiology, microbiology and diagnosis, as well as changes in medical and surgical management of infective endocarditis affecting native and prosthetic valves in adults, that have evolved during the past two decades. Significant changes have included an increasing involvement of prosthetic valves and nosocomially-acquired disease, an increased involvement of staphylococci as the causative agents, and a recognition that elderly individuals with degenerative valvular disease are the most vulnerable population. Topics still requiring study include whether and when valve replacement should be performed, and how to predict perivalvular complications or embolisation based on echocardiography findings. Optimisation of antimicrobial treatment schemes (choice of the antibiotic, dose and duration) also requires further investigation.

Endocarditis, Bacterial↗
PubMed1992

Pathological left-handedness and preserved function associated with a slowly evolving brain tumor.

The authors report the serial neuropsychological evaluations of a patient with acquired left-handedness who had a massive brain tumor that infiltrated the entire temporal and posterior parietal lobes of the left hemisphere. Although the patient had pre-operative impairment of non-verbal memory, follow-up assessment 31 and 66 months after the tumor was resected revealed cognitive functions to be in the high-average to superior range. This case demonstrates the sparing of neuropsychological functions that can be seen with a slowly evolving lesion. The authors suggest that such functional sparing may be due to transfer of function rather than to the residual function of tumor-infiltrated neuronal tissue. Possible mediators of functional preservation include slow lesion growth, the patient's youth at disease onset and the large size of the lesion.

Adult↗
PubMed2006

Achieving change through mutual development: supported online learning and the evolving roles of health and information professionals.

INTRODUCTION: Major changes in health care, within an information- and technology-rich age, are impacting significantly on health professionals and upon their education and training. Health information professionals-in both the National Health Service (NHS) and higher education (HE) contexts-are consequently developing their roles, skills and partnerships to meet the needs of flexible education and training. This article explores one facet of this-supported online learning and its impact on role development. METHODOLOGY: A case study approach was taken, aiming to explore how academics, health information professionals and learning technologists are developing supported online learning to explicitly address the e-literacy and information needs of health students within the context of NHS frameworks for education. This was contextualized by a literature review. RESULTS: The case study explores and discusses three dynamics--(i) The use of supported online learning tools by future health-care professionals throughout their professional training to ensure they have the appropriate e-literacy skills; (ii) the use of supported online learning by current health professionals to enable them to adapt to the changing environment; (iii) the development of the health information professional, and particularly their role within multi-disciplinary teams working with learning technologists and health professionals, to enable them to design and deliver supported online learning. CONCLUSIONS: The authors argue that, in this specific case study, health information professionals are key to the development of supported online learning. They are working successfully in collaboration and their roles are evolving to encompass learning and teaching activities in a wider context. There are consequently several lessons to be drawn in relation to professional education and role development.

Health Education↗
PubMed2005

Evolving connectionist system versus algebraic formulas for prediction of renal function from serum creatinine.

BACKGROUND: In clinical trials, equation 7 from the Modification of Diet in Renal Disease (MDRD) Study is the most accurate formula for the prediction of glomerular filtration rate (GFR) from serum creatinine. An alternative approach has been developed using evolving connectionist systems (ECOS), which are novel computing structures that can be trained to generate accurate output from a given set of input variables. This study aims to compare the prediction errors associated with each method, using data that reproduce routine clinical practice as opposed to the artificial setting of clinical trials. METHODS: The methods were compared using 441 radioisotope measurements of GFR in 178 chronic kidney disease patients from 12 centers in Australia and New Zealand. All clinical and laboratory measurements were obtained from the patients' center rather than central laboratories, as would be the case in routine clinical practice. Both the MDRD formula and ECOS used the same predictive variables, and both were optimized to the study cohort by stepwise regression and training, respectively. RESULTS: Mean measured GFR in the cohort was 22.6 mL/min/1.73 m(2). The bias and precision of the MDRD formula were -3.5 mL/min/1.73 m(2) and 34.5%, respectively, improving to -1.2 mL/min/1.73 m(2) and 31.1% after maximal optimization of the formula to study data. The bias and precision of the ECOS were 0.7 mL/min/1.73 m(2) and 32.6%, respectively, improving to -0.1 mL/min/1.73 m(2) and 16.6% after maximal optimization of the system to study data. The prediction of GFR using ECOS was improved by accounting for the center from where clinical and laboratory measurements originated within the connectionist model. CONCLUSION: Algebraic formulas will be associated with greater prediction error in routine clinical practice than in the original trials, and machine intelligence is more likely to predict GFR accurately in this setting.

Adult↗
PubMedDate not supplied

Pleiotropic mutation, modularity and evolvability.

The relationship between pleiotropy and the rate of evolution of a phenotypic character (evolvability) in a population is explored using computer simulations. I present results that suggest the rate of evolution of a phenotypic character may not decline when that character is pleiotropically associated to an increasing number of other characters, provided that the characters are under pure directional selection such that they are far from their optima relative to the average magnitude of a mutation. These conditions may be relevant during adaptive radiations. Adding pleiotropic associations to a set of characters in which one is under directional selection and the other is under stabilizing selection increases the rate of adaptation of the character under directional selection provided that the new characters that come to be pleiotropically associated are under directional selection. Thus, increasing the number of pleiotropic associations under these conditions increases the rate of adaptation of a character.

Adaptation, Physiological↗
PubMed2005

Future directions in behavioral headache research: applications for an evolving health care environment.

Three decades of research has produced effective behavioral treatments for migraine and tension-type headache, yet the full fruition of this research has not been realized. Further development and dissemination of behavioral treatments is needed to impact the large numbers of those with headache who potentially could benefit from these interventions. At the same time, an evolving health care environment challenges researchers and providers to employ greater efficiency and innovation in managing all chronic disorders. Hopefully, the recently published clinical trials guidelines for behavioral headache research will serve as a catalyst for production of quality empiricism that, in turn, will generate enhanced behavioral strategies and will optimize health care resource utilization. This article describes 10 areas of critical needs and research priorities for behavioral headache research, including: replication and extension of seminal studies using improved methodology; analysis of barriers to implementation of behavioral treatments; development of referral and treatment algorithms; behavioral compliance facilitation with medical interventions; development of a headache self-management model; integration of behavioral intervention within traditional medical practice; identification and management of comorbid psychopathology among headache patients; prevention of disease progression; analysis of behavioral therapeutic mechanisms, and development of innovative treatment formats and applications of information technologies.

Behavior Therapy↗
PubMedDate not supplied

Partial seizures evolving to infantile spasms.

We describe the clinical and electroencephalographic (EEG) manifestations of four patients with simultaneous EEG-video-telemetry recording (VTR) documented partial seizures evolving to infantile spasms. Clinical manifestations of the partial seizures included cessation of activity, staring, automatisms, increased limb tone, and laughter. In each case, partial seizures were followed by a cluster of infantile spasms. Infantile spasms preceded by partial seizures have not been previously documented.

Electroencephalography↗
PubMed2005

Hippocampal malformations do not necessarily evolve into hippocampal sclerosis.

PURPOSE: Hippocampal malformations have been proposed to underlie or evolve into hippocampal sclerosis, a common cause of refractory partial epilepsy. We report two patients with chronic epilepsy and developmental abnormalities of the hippocampus and cortex. We seek to address, in patients with recurrent convulsive seizures over many decades, whether hippocampal malformations necessarily progress to hippocampal sclerosis. METHODS: The first patient died at age 76 years and had experienced convulsive seizures for 43 years. The second patient, aged 64 years at death, had experienced convulsive seizures for 49 years. The brains were processed routinely. Immunohistochemistry for dynorphin and neuropeptide Y was performed. RESULTS: The first case exhibited bilateral perisylvian polymicrogyria. Both hippocampi demonstrated abnormal convolution in the CA1 subfield and subiculum. In the second case, periventricular heterotopia was found in the wall of the right lateral ventricle. The right hippocampus was abnormally oriented with excessive convolutions of the pyramidal cell layer between CA1 and the subiculum. In neither patient did the hippocampi exhibit neuronal loss. Furthermore, dynorphin immunohistochemistry revealed no reactivity in the molecular layers, and staining with neuropeptide Y confirmed normal numbers of hilar interneurons. CONCLUSIONS: These two cases demonstrate histologically that, even in long-standing epilepsy, malformations of the hippocampus do not necessarily develop into hippocampal sclerosis.

Aged↗
PubMed1988

Human systems as linguistic systems: preliminary and evolving ideas about the implications for clinical theory.

From our earliest practice of family therapy at medical schools, private family therapy institutes, and public agencies, our work with difficult populations that do not respond to current treatment technologies has reminded us of the inadequacies of our theoretical descriptions and the limitations of our expertise. This work has influenced our current, evolving clinical theory as we move from thinking of human systems as social systems defined by social organization (role and structure) to thinking of them as distinguished on the basis of linguistic and communicative markers. Hence, for us, the social unit we work with in therapy is a linguistic system distinguished by those who are "in language" about a problem, rather than by arbitrary and predetermined concepts of social organization. We call the therapy system a problem-organizing, problem-dis-solving system.

Communication↗