Hemorrhage risk with transjugular intrahepatic portosystemic shunt (TIPS) insertion at the main portal vein bifurcation with stent grafts

PURPOSE

The purpose of this study was to assess the incidence of major hemorrhage after transjugular intrahepatic portosystemic shunt (TIPS) insertion using a stent graft at the main portal vein bifurcation.

PATIENTS AND METHODS

TIPS insertion using stent grafts was performed in 215 patients due to non-variceal hemorrhage indications. There were 137 men and 78 women, with a mean age of 57 years±10.6 (SD) (range: 19-90 years). Based on retrospective review of portal venograms, TIPS inserted within 5mm from the portal vein bifurcation were considered "bifurcation TIPS", while those inserted 2cm or greater from the bifurcation were considered intrahepatic. Suspicion for acute major periprocedural hemorrhage were categorized as low, moderate, and high, based on the number of signs of hemorrhage.

RESULTS

Of 215 TIPS inserted for purposes other than hemorrhage, the TIPS was inserted at the portal bifurcation in 41 patients (29 men, 12 women; mean age, 55.9±11.7 (SD); range: 26-79 years) and intrahepatic in 62 patients (37 men, 25 women; mean age, 57.6±10.6 (SD), range: 34-82 years), whereas 112 were indeterminate in location. No active extravasations were identified on post-TIPS portal venograms. Suspicion for acute major hemorrhage was moderate or high in 3/41 (7%) of patients in the TIPS bifurcation group compared to 5/62 (8%) in the intrahepatic TIPS group (P>0.99). There were no significant differences in 30-day mortality rates (1/41 [2%] and 3/62 [5%] respectively; P> 0.99). No deaths or interventions were attributed to acute hemorrhage.

CONCLUSION

TIPS insertion at the portal bifurcation with stent grafts did not incur an elevated risk of hemorrhagic complications.

Bacteriocins and the assembly of natural Pseudomonas fluorescens populations

When competing for space and resources, bacteria produce toxins known as bacteriocins to gain an advantage over competitors. Recent studies in the laboratory have confirmed theoretical predictions that bacteriocin production can determine coexistence, by eradicating sensitive competitors or driving the emergence of resistant genotypes. However, there is currently limited evidence that bacteriocin‐mediated competition influences the coexistence and distribution of genotypes in natural environments, and what factors drive interactions towards inhibition remain unclear. Using natural soil populations of Pseudomonas fluorescens, we assessed the ability of the isolates to inhibit one another with respect to spatial proximity in the field, genetic similarity and niche overlap. The majority of isolates were found to produce bacteriocins; however, widespread resistance between coexisting isolates meant relatively few interactions resulted in inhibition. When inhibition did occur, it occurred more frequently between ecologically similar isolates. However, in contrast with results from other natural populations, we found no relationship between the frequency of inhibition and the genetic similarity of competitors. Our results suggest that bacteriocin production plays an important role in mediating competition over resources in natural settings and, by selecting for isolates resistant to local bacteriocin production, can influence the assembly of natural populations of P. fluorescens.

Co-evolutionary dynamics between public good producers and cheats in the bacterium Pseudomonas aeruginosa

The production of beneficial public goods is common in the microbial world, and so is cheating--the exploitation of public goods by nonproducing mutants. Here, we examine co-evolutionary dynamics between cooperators and cheats and ask whether cooperators can evolve strategies to reduce the burden of exploitation, and whether cheats in turn can improve their exploitation abilities. We evolved cooperators of the bacterium Pseudomonas aeruginosa, producing the shareable iron-scavenging siderophore pyoverdine, together with cheats, defective in pyoverdine production but proficient in uptake. We found that cooperators managed to co-exist with cheats in 56% of all replicates over approximately 150 generations of experimental evolution. Growth and competition assays revealed that co-existence was fostered by a combination of general adaptions to the media and specific adaptions to the co-evolving opponent. Phenotypic screening and whole-genome resequencing of evolved clones confirmed this pattern, and suggest that cooperators became less exploitable by cheats because they significantly reduced their pyoverdine investment. Cheats, meanwhile, improved exploitation efficiency through mutations blocking the costly pyoverdine-signalling pathway. Moreover, cooperators and cheats evolved reduced motility, a pattern that likely represents adaptation to laboratory conditions, but at the same time also affects social interactions by reducing strain mixing and pyoverdine sharing. Overall, we observed parallel evolution, where co-existence of cooperators and cheats was enabled by a combination of adaptations to the abiotic and social environment and their interactions.

Fewer invited talks by women in evolutionary biology symposia

Lower visibility of female scientists, compared to male scientists, is a potential reason for the under-representation of women among senior academic ranks. Visibility in the scientific community stems partly from presenting research as an invited speaker at organized meetings. We analysed the sex ratio of presenters at the European Society for Evolutionary Biology (ESEB) Congress 2011, where all abstract submissions were accepted for presentation. Women were under-represented among invited speakers at symposia (15% women) compared to all presenters (46%), regular oral presenters (41%) and plenary speakers (25%). At the ESEB congresses in 2001–2011, 9–23% of invited speakers were women. This under-representation of women is partly attributable to a larger proportion of women, than men, declining invitations: in 2011, 50% of women declined an invitation to speak compared to 26% of men. We expect invited speakers to be scientists from top ranked institutions or authors of recent papers in high-impact journals. Considering all invited speakers (including declined invitations), 23% were women. This was lower than the baseline sex ratios of early-mid career stage scientists, but was similar to senior scientists and authors that have published in high-impact journals. High-quality science by women therefore has low exposure at international meetings, which will constrain Evolutionary Biology from reaching its full potential. We wish to highlight the wider implications of turning down invitations to speak, and encourage conference organizers to implement steps to increase acceptance rates of invited talks.

Ependymoma in children: molecular considerations and therapeutic insights

A multi-modality approach that encompasses maximal surgical resection in combination with adjuvant therapy is critical for achieving optimal disease control in children with ependymoma. In view of its complex biology and variable response to therapy, ependymoma remains a challenge for clinicians involved in the care of these patients. Meanwhile, translation of molecular findings can characterize unique features of childhood ependymoma and their natural history. Furthermore, understanding the biology of pediatric ependymoma serves as a platform for development of future targeted therapies. In line with these goals, we review the molecular basis of pediatric ependymoma and its prognostic implications, as well as novel therapeutic advances in the management of ependymoma in children.

Repression of competition favours cooperation: experimental evidence from bacteria

Repression of competition (RC) within social groups has been suggested as a key mechanism driving the evolution of cooperation, because it aligns the individual's proximate interest with the interest of the group. Despite its enormous potential for explaining cooperation across all levels of biological organization, ranging from fair meiosis, to policing in insect societies, to sanctions in mutualistic interactions between species, there has been no direct experimental test of whether RC favours the spread of cooperators in a well-mixed population with cheats. To address this, we carried out an experimental evolution study to test the effect of RC upon a cooperative trait - the production of iron-scavenging siderophore molecules - in the bacterium Pseudomonas aeruginosa. We found that cooperation was favoured when competition between siderophore producers and nonsiderophore-producing cheats was repressed, but not in a treatment where competition between the two strains was permitted. We further show that RC altered the cost of cooperation, but did not affect the relatedness among interacting individuals. This confirms that RC per se, as opposed to increased relatedness, has driven the observed increase in bacterial cooperation.

Development and usage of eXtension's HorseQuest: an online resource

eXtension (pronounced e-extension) is an online resource transforming how faculty can collaborate and deliver equine education. As the first Community of Practice launched from eXtension, HorseQuest (HQ) offers free, interactive, peer-reviewed, online resources on a variety of equine-related topics at http://www.extension.org. This group has adapted traditional educational content to the online environment to maximize search engine optimization, to be more discoverable and relevant in the online world. This means that HQ resources are consistently being found on the first page of search results. Also, by researching key words searched by Internet users, HQ has guided new content direction and determined potential webcast topics based on relevance and frequency of those searches. In addition to establishing good search engine optimization, HQ has been utilizing the viral networking aspect of YouTube by uploading clips of existing equine educational videos to YouTube. HorseQuest content appears in mainstream media, is passed on by the user, and helps HQ effectively reach their community of interest (horse enthusiasts). HorseQuest partners with My Horse University to produce webcasts that combine concise knowledge exchange via a scripted presentation with viewer chat and incoming questions. HorseQuest has produced and published content including 12 learning modules, 8 webchats, 21 webcasts, and 572 videos segments. After the official public launch, there was a steady increase in average number of visits/mo and average page views/mo over the 26-mo period. These regressions show a statistically significant increase in visits (P < 0.001) of approximately 450 visits per month and a significant increase in page views (P = 0.004) of about 373 page views per month. HorseQuest is a resource for several state 4-H advancement and competition programs and will continue to be incorporated into traditional extension programs, while reaching and affecting global audiences.

Fitness correlates with the extent of cheating in a bacterium

There is growing awareness of the importance of cooperative behaviours in microbial communities. Empirical support for this insight comes from experiments using mutant strains, termed 'cheats', which exploit the cooperative behaviour of wild-type strains. However, little detailed work has gone into characterising the competitive dynamics of cooperative and cheating strains. We test three specific predictions about the fitness consequences of cheating to different extents by examining the production of the iron-scavenging siderophore molecule, pyoverdin, in the bacterium Pseudomonas aeruginosa. We create a collection of mutants that differ in the amount of pyoverdin that they produce (from 1% to 96% of the production of paired wild types) and demonstrate that these production levels correlate with both gene activity and the ability to bind iron. Across these mutants, we found that (1) when grown in a mixed culture with a cooperative wild-type strain, the relative fitness of a mutant is negatively correlated with the amount of pyoverdin that it produces; (2) the absolute and relative fitness of the wild-type strain in the mixed culture is positively correlated with the amount of pyoverdin that the mutant produces; and (3) when grown in a monoculture, the absolute fitness of the mutant is positively correlated with the amount of pyoverdin that it produces. Overall, we demonstrate that cooperative pyoverdin production is exploitable and illustrate how variation in a social behaviour determines fitness differently, depending on the social environment.

Phenotypic plasticity of a cooperative behaviour in bacteria

There is strong evidence that natural selection can favour phenotypic plasticity as a mechanism to maximize fitness in animals. Here, we aim to investigate phenotypic plasticity of a cooperative trait in bacteria--the production of an iron-scavenging molecule (pyoverdin) by Pseudomonas aeruginosa. Pyoverdin production is metabolically costly to the individual cell, but provides a benefit to the local group and can potentially be exploited by nonpyoverdin-producing cheats. Here, we subject bacteria to changes in the social environment in media with different iron availabilities and test whether cells can adjust pyoverdin production in response to these changes. We found that pyoverdin production per cell significantly decreased at higher cell densities and increased in the presence of cheats. This phenotypic plasticity significantly influenced the costs and benefits of cooperation. Specifically, the investment of resources into pyoverdin production was reduced in iron-rich environments and at high cell densities, but increased under iron limitation, and when pyoverdin was exploited by cheats. Our study demonstrates that phenotypic plasticity in a cooperative trait as a response to changes in the environment occurs in even the simplest of organisms, a bacterium.

Social semantics: altruism, cooperation, mutualism, strong reciprocity and group selection

From an evolutionary perspective, social behaviours are those which have fitness consequences for both the individual that performs the behaviour, and another individual. Over the last 43 years, a huge theoretical and empirical literature has developed on this topic. However, progress is often hindered by poor communication between scientists, with different people using the same term to mean different things, or different terms to mean the same thing. This can obscure what is biologically important, and what is not. The potential for such semantic confusion is greatest with interdisciplinary research. Our aim here is to address issues of semantic confusion that have arisen with research on the problem of cooperation. In particular, we: (i) discuss confusion over the terms kin selection, mutualism, mutual benefit, cooperation, altruism, reciprocal altruism, weak altruism, altruistic punishment, strong reciprocity, group selection and direct fitness; (ii) emphasize the need to distinguish between proximate (mechanism) and ultimate (survival value) explanations of behaviours. We draw examples from all areas, but especially recent work on humans and microbes.

Social learning about predators: a review and prospectus

In comparison with social learning about food, social learning about predators has received little attention. Yet such research is of potential interest to students of animal cognition and conservation biologists. I summarize evidence for social learning about predators by fish, birds, eutherian mammals, and marsupials. I consider the proposal that this phenomenon is a case of S-S classical conditioning and suggest that evolution may have modified some of the properties of learning to accommodate for the requirements of learning socially about danger. I discuss some between-species differences in the properties of socially acquired predator avoidance and suggest that learning may be faster and more robust in species in which alarm behavior reliably predicts high predatory threat. Finally, I highlight how studies of socially acquired predator avoidance can inform the design of prerelease antipredator training programs for endangered species.

Expectant management of prostate cancer

OBJECTIVES

To discuss the role of expectant management in the treatment of clinically localized prostate cancer.

DATA SOURCES

Published research and review articles, textbooks, and pending research publications.

CONCLUSIONS

Expectant management is a viable option for the treatment of clinically localized prostate cancer in carefully selected men.

IMPLICATIONS FOR NURSING PRACTICE

Nursing personnel along with physicians must work together to develop coping strategies for these men to deal with the continual uncertainty of this treatment program.

Testing Hamilton's rule with competition between relatives

Hamilton's theory of kin selection suggests that individuals should show less aggression, and more altruism, towards closer kin. Recent theoretical work has, however, suggested that competition between relatives can counteract kin selection for altruism. Unfortunately, factors that tend to increase the average relatedness of interacting individuals--such as limited dispersal--also tend to increase the amount of competition between relatives. Therefore, in most natural systems, the conflicting influences of increased competition and increased relatedness are confounded, limiting attempts to test theory. Fig wasp taxa exhibit varying levels of aggression among non-dispersing males that show a range of average relatedness levels. Thus, across species, the effects of relatedness and competition between relatives can be separated. Here we report that--contrary to Hamilton's original prediction but in agreement with recent theory--the level of fighting between males shows no correlation with the estimated relatedness of interacting males, but is negatively correlated with future mating opportunities.

Individual contributions to babysitting in a cooperative mongoose, Suricata suricatta

Evolutionary explanations of cooperative breeding based on kin selection have predicted that the individual contributions made by different helpers to rearing young should be correlated with their degree of kinship to the litter or brood they are raising. In the cooperative mongoose or meerkat, Suricata suricatta, helpers babysit pups at the natal burrow for the first month of pup life and frequent babysitters suffer substantial weight losses over the period of babysitting. Large differences in contributions exist between helpers, which are correlated with their age, sex and weight but not with their kinship to the young they are raising. Provision of food to some group members raises the contributions of individuals to babysitting. We discuss the implications of these results for evolutionary explanations of cooperative behaviour.

Selfish sentinels in cooperative mammals

Like humans engaged in risky activities, group members of some animal societies take turns acting as sentinels. Explanations of the evolution of sentinel behavior have frequently relied on kin selection or reciprocal altruism, but recent models suggest that guarding may be an individual's optimal activity once its stomach is full if no other animal is on guard. This paper provides support for this last explanation by showing that, in groups of meerkats (Suricata suricatta), animals guard from safe sites, and solitary individuals as well as group members spend part of their time on guard. Though individuals seldom take successive guarding bouts, there is no regular rota, and the provision of food increases contributions to guarding and reduces the latency between bouts by the same individual.

Frenular chordee: implications and treatment

Twenty of 75 male children undergoing elective circumcision demonstrated a ventral glandular chordee produced by an unusually prominent frenulum. Surgical incision of this prominent band of tissue relaxed the glandular traction (chordee), more adequately exposing the ventral inner prepuce, facilitating skin incisions, and permitting an improved cosmetic and functional outcome.

Effect of acoustic shock waves on clonogenic growth and drug sensitivity of human tumor cells in vitro

Focused acoustic shock waves were studied for their effects on human tumor cell viability, clonogenicity, and sensitivity to chemotherapeutic agents. The elastic shock waves used in this investigation were generated with the Dornier HM3-Lithotripter by underwater spark discharge with fixed electrical parameters employing a voltage of 18 kV and a capacitance of 80 nanoFarads. These waves are characterized by a fast varying compression phase, strong asymmetrical pressure and tension phases, and a maximum amplitude of roughly 10(8) Pascal (kg.m-1 s-2). Doses as high as 2000 focused shocks showed little effect on the viability of two different cell lines. There was, however, a dose dependent inhibition of tumor cell proliferation as determined by the growth of clones in soft agarose. Each of the two cell lines showed a unique degree of colony inhibition by shock waves. It was demonstrated that shock wave effects resulted from elastic shock wave interaction with the cells and were not caused by the emission of ultraviolet light coincident with shock wave generation. Shocks were applied at a rate of 100 minute-1 in a 200 l. water bath, thereby removing the possibility for temperature changes during treatments. After treatment with shock waves it was found that tumor cells became more sensitive to growth inhibition by chemotherapeutic agents. Cisplatin, doxorubicin, and 4-hydroperoxycyclophosphamide were each more effective in blocking cell growth after the target cells had been treated with acoustic shocks. Enhanced efficacies ranged from three to 10-fold potentiation of colony inhibition. These results indicate that weak shock waves, which can be focused to a defined target region, may have utility as a cancer treatment modality either alone or in combination with cytotoxic agents.

Effects of shock waves on the rat ovary

The studies reported in this paper were undertaken to investigate the effect of shock waves on ovarian function. In an initial study, five female Wistar rats underwent general anesthesia. One ovary was then exposed to 1500 shock waves at 20 kV using the Dornier XL-1 experimental lithotripter. One week following this treatment, the animals were sacrificed and both ovaries were step sectioned. We counted all follicles that contained both an oocyte and antrum. These follicles in turn were classified further as being healthy or atretic. No statistical difference in these counts was observed between shocked and unshocked ovaries taken from the same animal. In the definitive study, thirty-one adult female Wistar rats underwent unilateral oophorectomy. These rats were then divided into treated, sham-treated and control groups. The eleven treated animals were given general anesthesia and received 1500 shocks at 15 kV directed at their remaining ovary using the Dornier XL-1 lithotripter. The ten sham treated animals received identical anesthesia and duration of waterbath immersion as the treated group. In contrast, however, sham treated animals were positioned outside the path of the focused shock wave. The control group received no treatment. Normal estrus cycle was maintained in all groups following shock wave exposure. Two weeks after this exposure, all three groups of animals were allowed to mate. All animals in each of the three groups became pregnant. There was no statistical difference in litter size or fetal weights at three weeks gestation. No gross teratogenic effects were observed. The rat ovary appears to be structurally and functionally resistant to the shock wave energy levels used in this experiment.

Primary leiomyosarcoma of the inferior vena cava: a case report and review of the literature

Sixty-six cases of leiomyosarcoma of the inferior vena cava (IVC) have been reported. We present another case and review the characteristics and treatment of this rare tumor. IVC leiomyosarcomas spread by extension into adjacent tissue planes. Direct extension into the heart is known, but not into the kidneys, adrenals, or bowel. IVC leiomyosarcomas arising below the renal vein cause pain in the right-lower quadrant, back, and flank, and varying degrees of lower extremity edema; those arising in the middle caval segment cause right-upper-quadrant pain and sometimes renovascular hypertension; those arising above the hepatic vein cause varying manifestations of the Budd-Chiari syndrome. A reasonable approach to early diagnosis involves oral and intravenous contrast studies followed by computed tomography, angiography, and vena cavography. Aggressive surgical treatment is optimal in light of the tumor's slow growth pattern and relatively low malignant potential. (Metastases have been reported in fewer than 50% of cases). Tumors involving the lower IVC are most amenable to surgery; extensive collateral venous drainage of the left kidney preserves renal function during resection of middle caval tumors. Upper caval leiomyosarcomas are the least amenable to complete removal. Postoperative survival of all patients has ranged from a few weeks to eight years.