The effect of habitat on modern shark diversification.

Sharks occupy marine habitats ranging from shallow, inshore environments to pelagic, and deepwaters, and thus provide a model system for testing how gross habitat differences have shaped vertebrate macroevolution. Palaeontological studies have shown that onshore lineages diversify more quickly than offshore taxa. Among onshore habitats, coral reef-association has been shown to increase speciation rates in several groups of fishes and invertebrates. In this study, we investigated whether speciation rates are habitat dependent by generating the first comprehensive molecular timescale for shark divergence. Using phylogenetic comparative methods, we rejected the hypothesis that shelf (i.e. onshore) lineages have higher speciation rates compared to those occupying deepwater and oceanic (i.e. offshore) habitats. Our results, however, support the hypothesis of increased speciation rates in coral reef-associated lineages within the Carcharhinidae. Our new timetree suggests that the two major shark lineages leading to the extant shark diversity began diversifying mostly after the end-Permian mass extinction: the squalimorphs into deepwater and the galeomorphs into shelf habitats. We suggest that the breakdown of the onshore-offshore speciation rate pattern in sharks is mediated by success in deepwater environments through ecological partitioning, and in some cases, the evolution of morphological novelty.

Do habitat shifts drive diversification in teleost fishes? An example from the pufferfishes (Tetraodontidae).

Habitat shifts are implicated as the cause of many vertebrate radiations, yet relatively few empirical studies quantify patterns of diversification following colonization of new habitats in fishes. The pufferfishes (family Tetraodon-tidae) occur in several habitats, including coral reefs and freshwater, which are thought to provide ecological opportunity for adaptive radiation, and thus provide a unique system for testing the hypothesis that shifts to new habitats alter diversification rates. To test this hypothesis, we sequenced eight genes for 96 species of pufferfishes and closely related porcupine fishes, and added 19 species from sequences available in GenBank. We time-calibrated the molecular phylogeny using three fossils, and performed several comparative analyses to test whether colonization of novel habitats led to shifts in the rate of speciation and body size evolution, central predictions of clades experiencing ecological adaptive radiation. Colonization of freshwater is associated with lower rates of cladogenesis in pufferfishes, although these lineages also exhibit accelerated rates of body size evolution. Increased rates of cladogenesis are associated with transitions to coral reefs, but reef lineages surprisingly exhibit significantly lower rates of body size evolution. These results suggest that ecological opportunity afforded by novel habitats may be limited for pufferfishes due to competition with other species, constraints relating to pufferfish life history and trophic ecology, and other factors.

Factor analysis of open-field behavior in the rat (Rattus norvegicus): application of the three-way PARAFAC model to a longitudinal data set.

We examined the multivariate nature of open-field behavior in adult male rats (n = 26) by subjecting a longitudinal data set, obtained during 4 open-field test sessions (4 min in duration and spaced 48 h apart), to a three-way PARAFAC analysis. Unlike conventional two-way factor analytical models, the PARAFAC procedure allows for the direct factor analysis of 3-dimensional arrays, which then provided a unique factor solution to the longitudinal data set. The PARAFAC analysis extracted 2 factors: i) emotional reactivity and ii) exploratory behavior. These two factors changed in temporal prominence, with animals showing greater emotional reactivity on the first test session, and greater levels of exploration on the third and fourth test sessions. These results are in general agreement with previous findings which used more conventional factor analytic approaches. These findings indicate that multivariate procedures, such as the PARAFAC analysis, can be helpful in the quantitative characterization of behavioral phenomena in a more 'realistic' manner.

The Maze procedure: a new treatment for atrial fibrillation.

Atrial fibrillation is a dysrhythmia with lethal complications afflicting thousands of people each year. Unfortunately, atrial fibrillation is frequently resistant to medical therapy and other nonsurgical treatments, such as cardioversion and catheter ablation. Past surgical procedures to correct the dysrhythmia have also proved ineffective. A surgical procedure has been developed in which multiple incisions are made in the atrium, creating an electrical maze. The maze procedure restores atrioventricular synchrony while simultaneously preventing macroreentry within the atria. It thereby eliminates the clinical sequelae often associated with atrial fibrillation and improves the quality of life for those patients refractory to current methods of treatment.

In vivo microdialysis sampling for pharmacokinetic investigations.

In vivo microdialysis sampling coupled to liquid chromatography was used to study acetaminophen disposition in anesthetized rats. The pharmacokinetics of acetaminophen and its sulfate and glucuronide metabolites were determined using both microdialysis sampling and collection of whole blood. For microdialysis, samples were continuously collected for over 5 hr without fluid loss using a single experimental animal. Microdialysis sampling directly assesses the free drug concentration in blood. The pharmacokinetic results obtained with microdialysis sampling were the same as those obtained from blood collection. The administration of heparin, necessary when collecting blood samples, was found to double the elimination half-life of acetaminophen. Microdialysis sampling is a powerful tool for pharmacokinetic studies, providing accurate and precise pharmacokinetic data.

The effect of ketorolac tromethamine solution 0.5% in reducing postoperative inflammation after cataract extraction and intraocular lens implantation.

Ketorolac tromethamine solution 0.5% (1 drop 3 times daily) was more effective than the placebo vehicle solution in suppressing postoperative anterior ocular inflammation after extracapsular cataract extraction (ECCE) and intraocular lens (IOL) implantation in this multicenter, double-masked, randomized study. Four of 60 ketorolac-treated patients compared with 25 of 58 placebo-treated patients required supplemental corticosteroid therapy to suppress inflammation in the postoperative period which was statistically significant (P less than 0.001). Even though these supplemental steroid-treated patients were kept in the analysis, the placebo-treated group showed more evidence of anterior ocular inflammation as measured by anterior segment fluorophotometry. This was consistent with slit-lamp observations of increased anterior ocular inflammation. This study supported previous studies that suggested ketorolac tromethamine ophthalmic solution 0.5% was effective and safe as a nonsteroidal anti-inflammatory agent for topical use after ECCE and IOL implantation.