The lionfish Pterois sp. invasion: Has the worst-case scenario come to pass?

This review revisits the traits thought to have contributed to the success of Indo-Pacific lionfish Pterois sp. as an invader in the western Atlantic Ocean and the worst-case scenario about their potential ecological effects in light of the more than 150 studies conducted in the past 5 years. Fast somatic growth, resistance to parasites, effective anti-predator defences and an ability to circumvent predator recognition mechanisms by prey have probably contributed to rapid population increases of lionfish in the invaded range. However, evidence that lionfish are strong competitors is still ambiguous, in part because demonstrating competition is challenging. Geographic spread has likely been facilitated by the remarkable capacity of lionfish for prolonged fasting in combination with other broad physiological tolerances. Lionfish have had a large detrimental effect on native reef-fish populations in the northern part of the invaded range, but similar effects have yet to be seen in the southern Caribbean. Most other envisaged direct and indirect consequences of lionfish predation and competition, even those that might have been expected to occur rapidly, such as shifts in benthic composition, have yet to be realized. Lionfish populations in some of the first areas invaded have started to decline, perhaps as a result of resource depletion or ongoing fishing and culling, so there is hope that these areas have already experienced the worst of the invasion. In closing, we place lionfish in a broader context and argue that it can serve as a new model to test some fundamental questions in invasion ecology.

Photoperiodic changes in endocannabinoid levels and energetic responses to altered signalling at CB1 receptors in Siberian hamsters.

Siberian hamsters (Phodopus sungorus) adapt to seasonal environmental conditions with marked changes in body mass, primarily in the form of adiposity. Winter-like conditions (e.g. short days) are sufficient to decrease body mass by approximately 30% in part via reductions in food intake. The neuroendocrine mechanisms responsible for these changes are not well understood, and homeostatic orexigenic/anorexigenic systems of the hypothalamus provide little explanation. We investigated the potential role of endocannabinoids, which are known modulators of appetite and metabolism, in mediating seasonal changes in energy balance. Specifically, we housed hamsters in long or short days for 0, 3, or 9 weeks and measured endocannabinoid levels in the hypothalamus, brainstem, liver and retroperitoneal white adipose tissue (RWAT). An additional group of males housed in short days for 25 weeks were also compared with long-day controls. Following 9 weeks in short days, levels of the endocannabinoid 2-arachidonoylglycerol (2-AG) were significantly elevated in RWAT and reduced in brainstem, although they returned to long-day levels by week 25 in short-day males that had cycled back to summer-like energy balance. Endocannabinoid levels in these tissues correlated significantly with adiposity and change in body mass. No photoperiodic changes were observed in the hypothalamus or liver; however, sex differences in 2-AG levels were found in the liver (males > females). We further tested the effects of CB(1) receptor signalling on ingestive behaviour. Five daily injections of CB(1) antagonist SR141716 significantly reduced food intake and body mass but not food hoarding. Although the CB(1) agonist arachidonyl-2-chloroethylamide did not appreciably affect either ingestive behaviour, body mass was significantly elevated following 2 days of injections. Taken altogether, these findings demonstrate that endocannabinoid levels vary with sex and photoperiod in a site-specific manner, and that altered signalling at CB(1) receptors affects energy balance in Siberian hamsters.

Poor maternal nutrition followed by accelerated postnatal growth leads to telomere shortening and increased markers of cell senescence in rat islets.

Low birth weight (LBW) followed by accelerated postnatal growth is associated with increased risk of developing age-associated diseases such as type 2 diabetes. Gestational protein restriction in rats causes LBW, beta-cell dysfunction, and reduced longevity. These effects may be mediated by accelerated cellular aging. This study tested the hypothesis that LBW followed by rapid postnatal catch-up growth leads to islet telomere shortening through alterations in antioxidant defense capacity, stress/senescence marker proteins, and DNA repair mechanisms at the gene expression level. We used our rat model of gestational protein restriction (recuperated offspring) and control offspring. Southern blotting revealed shorter (P<0.001) islet telomeres in recuperated animals compared to controls. This was associated with increased expression of peroxiredoxin 1 (P<0.05), peroxiredoxin 3 (P<0.01), and heme oxygenase-1 (HO-1) (P<0.05), which are up-regulated under stress conditions. MnSOD expression was significantly (P<0.05) decreased in recuperated offspring, suggesting partial impairment of mitochondrial antioxidant defenses. Markers of cellular senescence p21 and p16 were also increased (P<0.01 and P<0.05, respectively) in the recuperated group. We conclude that maternal diet influences expression of markers of cellular stress and telomere length in pancreatic islets. This may provide a mechanistic link between early nutrition and growth and type 2 diabetes.

Applying population-based case mix adjustment in managed care: the Johns Hopkins Ambulatory Care Group system.

When analyzing medical utilization or other health care-related measurements across provider panels, case mix adjustment is required because "illness burden" is often unevenly distributed across these patient populations. This article develops the rationale for case mix adjustment and walks readers through the case mix adjustment process using the Johns Hopkins Ambulatory Care Group (ACG) Case-Mix System as a model. The ACG system is a population-oriented patient classification tool based on diagnoses assigned by providers and found in payors' data systems. The system categorizes patients according to illness burden. It does not categorize visits, encounters, or episodes. ACGs adjust for case mix differences in the analysis of ambulatory, laboratory, pharmacy, and total health care service delivery.

Bleomycin (review).

Since the original observation and description of the various forms of Bleomycin (BLM), numerous articles have appeared dealing with the activity on mammalian cells and its possible clinical use. The present review on this very important compound, although not very comprehensive, deals with the important characteristics; such as the action of DNA and cells, and its chromosome breaking effects. The manner in which the minute detail of the action of BLM on cells has helped to implement in vivo chemotherapeutic regimes, is also discussed.

Carcinogenic and possible mutagenic effects of stilboestrol in offspring exposed in utero.

The relevant literature has been reviewed and it appears that there is no doubt that in utero exposure to stilboestrol is related to the eventual development of vaginal adenocarcinoma in young females. Although cancer of other types are also prevalent, the incidence is not great and may be related to other types of drugs taken during pregnancy. The review attempts to correlate the genetic effects with the abnormal development, but on account of the scarcity of data such correlation is not possible. Further work on the genetic effects and the development of the lower genital tract in the female needs to be carried out.

PIP: A review of the literature concerning the relationship between in utero exposure to stilbestrol and the later development of carcinoma of the vagina in young women is presented. The literature does confirm the causal relationship which seems to be triggered by hormonal changes at puberty. The critical time of exposure seems to be around the 8th week of pregnancy during the early differentiation of the female genital tract. Data on genetic effects of stilbestrol are too few to provide any conclusions. However, it is unlikely that genetically disturbed cells would exhibit the latency period seen in this cancer. Further research must be carried out in long-term projects to determine whether genetic effects are, in fact, present.

Temporal summation and refractoriness in hypothalamic reward neurons as measured by self-stimulation behavior.

A neurophysiological technique of double-pulse stimulation has been applied to freely moving rats with chronic indwelling electrodes in the hypothalamic reward area. Self-stimulation thresholds, measured as a function of the interpulse interval, generated curves with time constants characteristic of refractory periods and temporal synaptic summation. The results indicate a way of studying central neuronal processes for which the overt behavior of the animal is the dependent variable.