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At least 559 records · Page 31Linked to original sources
PubMed2000

Molecular systematics of the African electric fishes (Mormyroidea: teleostei) and a model for the evolution of their electric organs.

We present a new molecular phylogeny for 41 species of African mormyroid electric fishes derived from the 12S, 16S and cytochrome b genes and the nuclear RAG2 gene. From this, we reconstruct the evolution of the complex electric organs of these fishes. Phylogenetic results are generally concordant with earlier preliminary molecular studies of a smaller group of species and with the osteology-based classification of Taverne, which divides the group into the Gymnarchidae and the Mormyridae, with the latter including the subfamilies Petrocephalinae (Petrocephalus) and Mormyrinae (all remaining taxa). However, we find that several genera previously recognized by Taverne are non-monophyletic. Within the Mormyrinae, the genus Myomyrus is the sister group to all the remaining taxa. Other well-supported clades within this group are recovered. A reconstruction of electrocyte evolution on the basis of our best-supported topology suggests that electrocytes with penetrating stalks evolved once early in the history of the mormyrids followed by multiple paedomorphic reversals to electrocytes with non-penetrating stalks.

Animals↗
PubMedDate not supplied

Evolution of a model for the thrombolysis of acute stroke patients.

The National Audit Office (NAO, 2005) has reported that the priority afforded to stroke care should be increased, given its impact on health and cost to the NHS. It recommends improvements in preventing, treating and managing stroke patients in line with recent evidence. Thrombolysis for acute ischaemic stroke is a proven treatment that produces good results in significant numbers of patients (Mar et al, 2005). However, owing to various barriers, many hospitals in the UK have failed to implement effective systems to facilitate the delivery of this treatment to acute stroke patients. These barriers include a lack of skill, nursing knowledge, and 'fast-track' organization relating to thrombolysis as a treatment for acute stroke. Fears of intracranial bleeding and lack of appropriate stroke unit beds and issues of consent have also been identified as further problems (Innes and International Stroke Trial (IST-3), 2003). Taking these concerns into consideration, Scarborough District General Hospital has developed a multidisciplinary model with the Coronary Care Unit (CCU), integral to the delivery of treatment. Between 2003 and 2005, 24 stroke patients have received thrombolysis treatment and have been cared for in CCU. Outcome results have been positive, with 51% of patients demonstrating a significant benefit at 7 days post-stroke. This model has broken traditional professional and speciality boundaries to allow patients to receive treatments they otherwise would not have received. Moreover, it provides the potential for further exploration into the wider implementation of thrombolysis for acute stroke patients in the UK.

Acute Disease↗
PubMed1997

Three-dimensional modeling and molecular evolution of Matrix Cell Adhesion Molecule #2: MAT-CAM 2.

Our research group has recently reported the partial amino acid sequence of an aortic adventitial collagen-associated fibrillar protein, which may be the target of an autoimmune response in patients with abdommal aortic aneurysms (AAA). Its apparent molecular weight is approximately 40 kDa, so we have named it aneurysm-associated antigenic protein-40 kDa (AAAP-40). It has similarities to microfibril-associated glycoprotein-36 kDa (MAGP-36), which was reported by Kobayashi et al. to have a tissue distribution limited to the aorta in pig; unlike other microfibrillar proteins which appear to distribute ubiquitously throughout the body with elastin. Accordingly, if AAAP-40 is the human homolog of MAGP-36, it would explain how an autoimmune reaction against this protein might have consequences more or less limited to the aorta and its branches.

Journal Article↗
PubMedDate not supplied

[Evaluation of the evolution rate in Eigen's and Kuhn's models].

The stage evolution of a "population" consisting of informational sequences having fixed length N is investigated. It is assumed that at each stage sequences of a "population" are selected, reproduced, mutated and diluted. Character of an evolution is revealed and the evolution rate is estimated for different values of N, "population" size n, and a number of different symbols lambda in sequences. According to the obtained estimations it is possible to find sequences in an evolution process which are close to the "optimum" one using far less number of sequences (approximately lambda N4) than for a random search (approximately lambda N).

Animals↗
PubMed1993

Modeling and simulating the evolution of resistance against antibiotics.

An epidemiological model is proposed for the spread of resistance against antibiotics in populations of bacterial pathogens. The host population, which is assumed to be constant, is divided into three compartments, viz. susceptible, hosts infected by an antibiotic-sensitive strain and hosts infected by a resistant strain. It is further assumed that susceptibles can be infected by either strain and that there is a possibility for cross-infection between hosts infected by the two strains. The rate of cross-infection can be enhanced by mutations or the transfer of plasmids conferring resistance. Equilibrium analysis was performed in order to determine which of the strain 'wins' the competition by the host. It is assumed that the eventual shift in the competition between the two strains is due to treatment by antibiotic (selective pressure).

Amikacin↗
PubMed1995

Evolution of control system models of ocular accommodation, vergence and their interaction.

This paper reviews the evolution of inferential models describing ocular accommodation and vergence, which have been developed using the techniques of control engineering. The models are developed by inferring that the observed behaviour of the ocular systems could be produced by particular types of feedback control systems. The models are subsequently tested and improved by modifications resulting from the comparison of model predictions with physiological experimentation. Current models of accommodation and vergence have had considerable success in describing both the steady-state and dynamic behaviours of the individual systems. However, controversy currently exists among researchers, particularly with respect to the composition of models that describe the interaction of the two systems.

Accommodation, Ocular↗