Exploring chromosome evolution in 250 million year old groups of dragonflies and damselflies (Insecta:Odonata).

Using recently published chromosome-length genome assemblies of two damselfly species, Ischnura elegans and Platycnemis pennipes, and two dragonfly species, Pantala flavescens and Tanypteryx hageni, we demonstrate that the autosomes of Odonata have undergone few fission, fusion, or inversion events, despite 250 million years of separation. In the four genomes discussed here, our results show that all autosomes have a clear ortholog in the ancestral karyotype. Despite this clear chromosomal orthology, we demonstrate that different factors, including concentration of repeat dynamics, GC content, relative position on the chromosome, and the relative proportion of coding sequence all influence the density of syntenic blocks across chromosomes. However, these factors do not interact to influence synteny the same way in any two pairs of species, nor is any one factor retained in all four species. Furthermore, it was previously unknown whether the micro-chromosomes in Odonata are descended from one ancestral chromosome. Despite structural rearrangements, our evidence suggests that the micro-chromosomes in the sampled Odonata do indeed descend from an ancestral chromosome, and that the micro-chromosome in P. flavescens was lost through fusion with autosomes.

Opportunities and Challenges for Including Oyster-Mediated Denitrification in Nitrogen Management Plans.

Nitrogen pollution is one of the primary threats to coastal water quality globally, and governmental regulations and marine policy are increasingly requiring nitrogen remediation in management programs. Traditional mitigation strategies (e.g., advanced wastewater treatment) are not always enough to meet reduction goals. Novel opportunities for additional nitrogen reduction are needed to develop a portfolio of long-term solutions. Increasingly, in situ nitrogen reduction practices are providing a complementary management approach to the traditional source control and treatment, including recognition of potential contributions of coastal bivalve shellfish. While policy interest in bivalves has focused primarily on nitrogen removal via biomass harvest, bivalves can also contribute to nitrogen removal by enhancing denitrification (the microbial driven process of bioavailable nitrogen transformation to di-nitrogen gas). Recent evidence suggests that nitrogen removed via enhanced denitrification may eclipse nitrogen removal through biomass harvest alone. With a few exceptions, bivalve-enhanced denitrification has yet to be incorporated into water quality policy. Here, we focus on oysters in considering how this issue may be addressed. We discuss policy options to support expansion of oyster-mediated denitrification, describe the practical considerations for incorporation into nitrogen management, and summarize the current state of the field in accounting for denitrification in oyster habitats. When considered against alternative nitrogen control strategies, we argue that enhanced denitrification associated with oysters should be included in a full suite of nitrogen removal strategies, but with the recognition that denitrification associated with oyster habitats will not alone solve our excess nitrogen loading problem.

Competition-defense tradeoffs and the maintenance of plant diversity.

Ecologists have long observed that consumers can maintain species diversity in communities of their prey. Many theories of how consumers mediate diversity invoke a tradeoff between species' competitive ability and their ability to withstand predation. Under this constraint, the best competitors are also most susceptible to consumers, preventing them from excluding other species. However, empirical evidence for competition-defense tradeoffs is limited and, as such, the mechanisms by which consumers regulate diversity remain uncertain. We performed a meta-analysis of 36 studies to evaluate the prevalence of the competition-defense tradeoff and its role in maintaining diversity in plant communities. We quantified species' responses to experimental resource addition and consumer removal as estimates of competitive ability and resistance to consumers, respectively. With this analysis, we found mixed empirical evidence for a competition-defense tradeoff; in fact, competitive ability tended to be weakly positively correlated with defense overall. However, when present, negative relationships between competitive ability and defense influenced species diversity in the manner predicted by theory. In the minority of communities for which a tradeoff was detected, species evenness was higher, and resource addition and consumer removal reduced diversity. Our analysis reframes the commonly held notion that consumers structure plant communities through a competition-defense tradeoff. Such a tradeoff can maintain diversity when present, but negative correlations between competitive ability and defense were less common than is often assumed. In this respect, this study supports an emerging theoretical paradigm in which predation interacts with competition to both enhance and reduce species diversity.

Round ligament varices: sonographic appearance in pregnancy.

Round ligament varices (RLV) are an important clinical entity as they may cause hernia-like symptoms in the absence of a true hernia. When this condition is diagnosed correctly, unnecessary intervention may be prevented. We aimed to determine the significance and anatomy of RLV in pregnancy and to review and describe their clinical and sonographic appearance. We followed prospectively five patients who presented during pregnancy with clinical symptoms suspicious of an inguinal hernia. All patients were diagnosed with RLV on ultrasound examination. All patients were managed conservatively and in all five cases, RLV resolved spontaneously postpartum. The diagnosis of RLV should be considered in pregnant women presenting with a groin mass. Sonography is diagnostic and can save unnecessary surgical exploration and associated morbidity.

Lymphadenectomy for papillary thyroid cancer: changes in practice over four decades.

AIMS: Lymphadenectomy in the management of papillary thyroid cancer (PTC) has evolved. The aim of this study was to examine the changing role of neck dissection as reflected in the practice of a large thyroid unit over four decades. METHODS: A retrospective cohort study of patients that underwent primary thyroid surgery for papillary cancer in a single unit in the period 1958-2002. Nine 5-year periods were considered and the data relevant to the treatment of the regional lymph nodes reviewed. RESULTS: Nine hundred patients with PTC underwent surgery between 1958 and 2002 of whom 32.7% underwent lymph node dissection (LND). The use of lymphadenectomy increased from 21.4% in 1958-1962 to 48.1% in 1998-2002 of which 84% underwent a selective lymph node dissection (SLND)-a dissection where the LND is determined by the extent of the disease encountered. The mean number of nodes removed during SLND was 12.6 (range 1-56) of which a mean of 3.1 (24.8%) (0-19) were involved by the disease. Cervical levels 6 and level 4 were those most frequently dissected. There was no statistically significant difference in the complication rates in patients undergoing neck dissection and those not. CONCLUSION: The four decade experience reflects a move away from modified radical neck dissection and cherry picking towards SLND. Growing evidence suggests that lymphadenopathy in adult PTC is an adverse prognostic factor. SLND, a lymphadenectomy tailored to the extent of the disease process, is the coherent treatment for PTC since it serves the dual purpose of staging as well as control of local disease. This can be achieved with little morbidity when performed in a specialist centre.

Novel technique for placement of hemodialysis catheters using a combined open procedure with the Seldinger micropuncture technique.

Percutaneous placement of large-diameter dialysis catheters via the Seldinger technique can be technically challenging in patients with coagulopathy, difficult anatomy, or several previous central line insertions. We describe a method for achieving safer access by combining an open approach to delineate the venous anatomy of the chest wall, with a micropuncture device and smaller diameter guidewire to gain intravascular access to the cephalic vein or its major tributaries. Serial dilation of otherwise unusable vessels can then permit successful and safer hemodialysis catheter insertion in these difficult cases.

Cinematic nuclear scintigraphy reliably directs surgical intervention for patients with gastrointestinal bleeding.

HYPOTHESIS: Cinematic technetium Tc 99m red blood cell ((99m)Tc-RBC) scans, in which real-time scanning is performed and analyzed, can accurately localize gastrointestinal bleeding and thus direct selective surgical intervention. DESIGN: Retrospective medical record review with historical controls. SETTING: Large, university-affiliated public hospital in urban setting. PATIENTS: Twenty-six patients presenting with upper and lower gastrointestinal hemorrhage who underwent cinematic (99m)Tc-RBC scan examinations between 1990 and 1997 and required surgical intervention to control the bleeding. INTERVENTIONS: All patients with gastrointestinal bleeding underwent open surgical procedures to provide cessation of bleeding and resection of appropriate abnormalities. MAIN OUTCOME MEASURES: Patient outcome was based on correlation between preoperative RBC scans and intraoperative findings, surgical pathology, and postoperative clinical course. RESULTS: Twenty-five (96%) of 26 scans were interpreted as positive for gastrointestinal bleeding. In 22 of these 25 scans, the site of bleeding was correctly identified for a sensitivity of 88%. One or more additional diagnostic tests were performed on 19 (73%) of 26 patients, and included angiography and flexible endoscopy. The most common operation performed to control bleeding was a hemicolectomy (14/26). Diverticulosis was the most prevalent diagnosis (46%). Two patients (8%) experienced rebleeding after operation. The overall mortality rate was 19% (5/26). CONCLUSIONS: Cinematic (99m)Tc-RBC scintigraphy is a sensitive, noninvasive alternative to mesenteric angiography for accurately localizing the site of gastrointestinal hemorrhages. As such, this technique can be reliably used to direct selective surgical intervention.

Extracellular matrix regulates the hepatocellular heat shock response.

BACKGROUND: Cirrhosis is characterized by the accumulation of collagen within the extracellular matrix (ECM) of the liver and progressive hepatocellular dysfunction. Since recent studies have shown that the ECM can modulate cellular function, we examined whether the ECM could contribute to hepatocellular dysfunction. To address this question we examined hepatocyte behavior in two different ECM environments. MATERIALS AND METHODS: Primary rat hepatocytes were cultured as a monolayer on collagen or as multicellular aggregates (spheroids) within a laminin-rich ECM. Hepatocytes were then compared for viability, response to proinflammatory cytokines, and their capacity to activate a heat shock response and adopt a thermotolerant phenotype. In addition, we compared the ability of prior heat shock exposure to protect hepatocytes from tumor necrosis factor (TNF) alpha/actinomycin-D-induced apoptosis in the two different ECM environments. RESULTS: Hepatocytes cultured as a monolayer on collagen exhibited decreased viability, underwent spontaneous apoptosis, and displayed an attenuated cytokine-stimulated nitric oxide production compared to hepatocytes cultured as spheroids. In response to heat, hepatocytes in both ECM environments expressed inducible heat shock protein 70 (hsp72). But, only the hepatocyte spheroids exhibited thermotolerance in response to a subsequent thermal challenge. In contrast to previous reports, induction of the heat shock response failed to protect hepatocytes against TNFalpha-induced apoptosis. CONCLUSIONS: These data demonstrate that the ECM can play an integral role in specific hepatocellular behaviors. Furthermore, the progressive deposition of collagen within the ECM, which is characteristic of fibrotic liver diseases, may directly contribute to the progressive hepatocellular dysfunction observed in cirrhosis. Hepatocellular viability, response to proinflammatory cytokines, heat shock response, and thermotolerance were all altered depending on the composition of the ECM. In contrast, TNFalpha-induced apoptosis was independent of the composition of the ECM.

The lipemia of sepsis: triglyceride-rich lipoproteins as agents of innate immunity.

Bacterial endotoxin (LPS) elicits dramatic responses in the host including elevated plasma lipid levels due to the increased synthesis and secretion of triglyceride (TG)-rich lipoproteins by the liver, and the inhibition of lipoprotein lipase. This cytokine-induced hyperlipoproteinemia, clinically termed the "lipemia of sepsis", was customarily thought to represent the mobilization of lipid stores to fuel the host response to infection. However, since lipoproteins can also bind and neutralize LPS, we hypothesize that TG-rich lipoproteins (VLDL and chylomicrons) are also components of an innate, non-adaptive host immune response to infection. Herein we review data demonstrating the capacity of lipoproteins to bind LPS, protect against LPS-induced toxicity, and modulate the overall host response to this bacterial toxin. Lastly, we propose a pathway whereby lipoprotein-bound LPS may represent a novel, endogenous mechanism for regulating the hepatic acute phase response.

Prophylactic antiemetics for laparoscopic cholecystectomy: a comparison of perphenazine, droperidol plus ondansetron, and droperidol plus metoclopramide.

STUDY OBJECTIVE: To compare the prophylactic administration of ondansetron plus droperidol, droperidol plus metoclopramide, and perphenazine to determine effects on postoperative nausea, vomiting, and sedation after laparoscopic cholecystectomy. DESIGN: Prospective, randomized, double-blind study. SETTING: University medical center. PATIENTS: 212 ASA physical status I and II adults presenting for laparoscopic cholecystectomy. INTERVENTIONS: Patients were randomly assigned to receive one of three prophylactic antiemetic drug combinations: ondansetron 4 mg plus droperidol 0.625 mg (Group OD), droperidol 0.625 mg plus metoclopramide 10 mg (Group DM), or perphenazine 5 mg (Group P). Study drugs were administered intravenously after induction of general anesthesia. MEASUREMENTS AND MAIN RESULTS: The groups were similar with respect to gender, age, weight, duration of surgery, numbers of patients receiving intraoperative atropine or ephedrine, number admitted overnight, and time to discharge home. Patients in Group P used lower total doses of opioids than did patients in Group OD. There were no significant differences in postoperative nausea, pain, or sedation scores, in numbers of patients requiring antiemetics (Group OD, 13 of 66; Group DM, 15 of 66; Group P, 14 of 68), or in numbers of patients vomiting, either in hospital or during the first postoperative day. CONCLUSIONS: These three drug regimens are equivalent for antiemetic prophylaxis before laparoscopic cholecystectomy.

QEEG and neuropsychological profiles of patients prior to undergoing cardiopulmonary bypass surgical procedures.

Within our patient population undergoing cardiopulmonary bypass (CPB) surgery, evidence of pre-existing cortical dysfunction was highly prevalent, with 39.5% displaying QEEG and/or neuropsychological (NP) abnormality. These patients with pre-existing QEEG or NP abnormality were at increased risk for developing both short and long-term postoperative deficits in NP performance. Preoperative QEEG showed increased sensitivity and specificity over preoperative NP performance for predicting NP performance one week after surgery. One week after surgery NP deficits were quite common occurring in 40.6% of the patients. Two to three months after surgery evidence of continued NP performance deficits were still present in 28.1% of the patients. Preoperative NP performance predicted 3 month postoperative NP performance quite well, although preoperative QEEG proved equally effective.

Prophylactic antiemetics for laparoscopic cholecystectomy: ondansetron versus droperidol plus metoclopramide.

Two hundred adults undergoing laparoscopic cholecystectomy were enrolled in a prospectively randomized, double-blind investigation comparing ondansetron, 4 mg (Group O) with the combination of droperidol, 0.625 mg, and metoclopramide, 10 mg (Group DM). Antiemetic drugs were administered intravenously (IV) after induction of general anesthesia (propofol, desflurane). Moderate or severe nausea in the postanesthesia care unit was treated with the cross-over drug, i.e., ondansetron for patients in Group DM or droperidol plus metoclopramide for patients in Group O. Data were analyzed using t-tests and chi 2 analyses, with P < 0.05 considered statistically significant. The groups were similar with respect to gender, age, weight, duration of surgery, number receiving intraoperative atropine or ephedrine, number admitted over-night, and time to discharge home. Of 102 patients in Group O, 44 required antiemetics in the postanesthesia care unit, compared with 24 of 98 patients in Group DM (P < 0.01). One patient (in Group DM) was admitted for persistent nausea. In conclusion, droperidol 0.625 mg IV in combination with metoclopramide 10 mg IV was more effective in preventing postoperative nausea than was ondansetron 4 mg IV in patients undergoing laparoscopic cholecystectomy, with no difference in the time to discharge.