Antimicrobial susceptibility of Edwardsiella ictaluri

Edwardsiella ictaluri isolates collected over the past 7 yr from outbreaks of disease in fish occurring in different geographic areas were screened against 37 antimicrobial agents. Edwardsiella ictaluri were found to be susceptible to most agents active against gram negative bacteria such as aminoglycosides, cephalosporins, the "newer" penicillins, quinolones, tetracyclines, chloramphenicol, nitrofurantoin, and potentiated sulfonamides. Resistance was observed against colistin, sulfonamides, and several agents regarded as effective for gram positive bacteria. There was no evidence of unusual antimicrobial resistance associated with E. ictaluri or of developing resistance.     

Global analysis of a model of plasmid-bearing,plasmid-free competition in a chemostat

A model of competition between plasmid-bearing and plasmid-free organisms in a chemostat was proposed in a paper of Stephanopoulis and Lapidus. The model was in the form of a system of nonlinear ordinary differential equations. Such models are relevant to commercial production by genetically altered organisms in continuous culture. The analysis there was local (using index arguments). This paper provides a mathematically rigorous analysis of the global asymptotic behavior of the governing equations in the case of uninhibited specific growth rate.Research supported by the National Council of Science, Republic of ChinaResearch supported by National Science Foundation Grant, DMS-9204490Research supported by the Natural Science and Engineering Council of Canada. This author's contribution was made while on research leave visiting the Department of Ecology and Evolutionary Biology at Princeton University. She would especially like to thank Simon Levin for his guidance as well as for providing an exceptional working environment     

Polymorphism of the gene encoding the alpha subunit of the stimulatory G-protein of adenylyl cyclase (GNAS1)

A two-allele polymorphism of the human gene encoding for the alpha subunit of the guanine nucleotide-binding protein is described.     

Citation Analysis May Severely Underestimate the Impact of Clinical Research as Compared to Basic Research

Background

Citation analysis has become an important tool for research performance assessment in the medical sciences. However, different areas of medical research may have considerably different citation practices, even within the same medical field. Because of this, it is unclear to what extent citation-based bibliometric indicators allow for valid comparisons between research units active in different areas of medical research.

Methodology

A visualization methodology is introduced that reveals differences in citation practices between medical research areas. The methodology extracts terms from the titles and abstracts of a large collection of publications and uses these terms to visualize the structure of a medical field and to indicate how research areas within this field differ from each other in their average citation impact.

Results

Visualizations are provided for 32 medical fields, defined based on journal subject categories in the Web of Science database. The analysis focuses on three fields: Cardiac & cardiovascular systems, Clinical neurology, and Surgery. In each of these fields, there turn out to be large differences in citation practices between research areas. Low-impact research areas tend to focus on clinical intervention research, while high-impact research areas are often more oriented on basic and diagnostic research.

Conclusions

Popular bibliometric indicators, such as the h-index and the impact factor, do not correct for differences in citation practices between medical fields. These indicators therefore cannot be used to make accurate between-field comparisons. More sophisticated bibliometric indicators do correct for field differences but still fail to take into account within-field heterogeneity in citation practices. As a consequence, the citation impact of clinical intervention research may be substantially underestimated in comparison with basic and diagnostic research.     

A competition model with dynamically allocated inhibitor production

The chemostat is a basic model for competition in an open system and a model for the laboratory bio-reactor (CSTR). Inhibitors in open systems are studied with a view of detoxification in natural systems and of control in bio-reactors. This study allows the amount of resource devoted to inhibitor production to depend on the state of the system. The feasibility of one dependence is provided by quorum sensing. In contrast to the constant allocation case, a much wider set of outcomes is possible including interior, stable rest points and stable limit cycles. These outcomes are important contrasts to competitive exclusion or bistable attractors that are often the outcomes for competitive systems. The model consists of four non-linear ordinary differential equations and computer software is used for most of the stability calculations.     

A survey of mathematical models of competition with an inhibitor

Mathematical models of the effect of inhibitors on microbial competition are surveyed. The term inhibitor is used in a broad sense and includes toxins, contaminants, allelopathic agents, etc. This includes both detoxification where the inhibitor is viewed as a pollutant and control where the inhibitor is viewed as an aid to controlling a bioreactor. The inhibitor may be supplied externally or may be created as an anti-competitor toxin. This includes plasmid-bearing, plasmid-free competition. The literature is spread across journals in different disciplines and with different notation. The survey attempts to present the mathematical models and the results of the corresponding analysis within a common framework and notation. Detailed mathematical proofs are not given but the methods of proof are indicated, references cited, and the results presented in tables. Open problems are indicated where there is a gap in the theory.     

Aspirin and indomethacin: Effect on instillation/abortion time of mid-trimester hypertonic saline induced abortion

Two acidic non steroid anti-inflammatory drugs, aspirin (acetylsalicyclic acid) and indomethacin were administered to patients undergoing mid-trimester saline induced abortion, to test their analgesic properties and to observe their effect on the instillation/abortion time interval. Both drugs when administered to patients undergoing mid-trimester saline abortion prolong significantly the instillation/abortion interval. These observations on human mid-trimester saline induced abortion treated with aspirin and indomethacin correspond with experimental data recently published relative to the antiprostaglandin activity of acidic non steroid drugs. The analgesic properties of both aspirin and indomethacin are difficult to assess accurately because of the highly emotional state of the patients studied; indomethacin, however, appears to be more effective for the prodromal abortion type of pain experienced by the patient but is still inadequate for sedation for the pain resulting from strong uterine contractions.     

Multi-species integrative biclustering

We describe an algorithm, multi-species cMonkey, for the simultaneous biclustering of heterogeneous multiple-species data collections and apply the algorithm to a group of bacteria containing Bacillus subtilis, Bacillus anthracis, and Listeria monocytogenes. The algorithm reveals evolutionary insights into the surprisingly high degree of conservation of regulatory modules across these three species and allows data and insights from well-studied organisms to complement the analysis of related but less well studied organisms.