The toxicity of metal mixtures to the estuarine mysid Neomysis integer (Crustacea: Mysidacea) under changing salinity

Water quality criteria are mainly based on data obtained in toxicity tests with single toxicants. Several authors have demonstrated that this approach may be inadequate as the joint action of the chemicals is not taken into account. In this study, the combined effects of six metals on the European estuarine mysid Neomysis integer (Leach, 1814) were examined. Acute 96-h toxicity tests were performed with mercury, copper, cadmium, nickel, zinc and lead, and this as single compounds and as a mixture of all six. The concentrations of the individual metals of the equitoxic mixtures were calculated using the concentration-addition model. The 96-h LC50's for the single metals, at a salinity of 5 per thousand, ranged from 6.9 to 1140 microg/l, with the following toxicity ranking: Hg>Cd>Cu>Zn>Ni>Pb. Increasing the salinity from 5 to 25 per thousand resulted in lower toxicity and lower concentrations of the free ion (as derived from speciation calculations) for all metals. This salinity effect was strongest for cadmium and lead and could be attributed to complexation with chloride ions. The toxicity of nickel, copper and zinc was affected to a smaller extent by salinity. The 96-h LC50 for mercury was the same for both salinities. In order to evaluate the influence of changing salinity conditions on the acute toxicity of metal mixtures, tests were performed at different salinities (5, 10, 15 and 25 per thousand ). The 96-h LC50 value (1.49 T.U.) of the metal mixture, at a salinity of 5 per thousand, was clearly lower than the expected value (6 T.U.) based on the non-additive hypothesis, thus confirming the additive effect of these metals in the marine/estuarine environment. Changing salinity had a profound effect on the toxicity of the mixture. The toxicity clearly decreased with increasing salinity until 15 per thousand. Higher salinities (25 per thousand ) had no further influence on the 96-h LC50 of the mixture which is situated at a value between 4.4 and 4.6. Finally, the relative sensitivity to the selected metals was compared with the relative sensitivity of the commonly used mysid Americamysis (=Mysidopsis) bahia.     

Type I collagen promotes the malignant phenotype of pancreatic ductal adenocarcinoma.

PURPOSE: The purpose of this study was to determine the role of functional interactions between pancreatic cancer cells and pancreatic stellate cells (PSCs) in the formation of the desmoplastic reaction (DR) in pancreatic cancer and to characterize the effect of type I collagen (the predominant component of the DR) on pancreatic cancer cell phenotype. EXPERIMENTAL DESIGN: PSCs and type I collagen were identified in sections of pancreatic cancer using immunohistochemistry, and their anatomic relationship was studied. Interactions among pancreatic cancer cell lines (MIA PaCa-2, Panc-1, and AsPC-1), primary cultures of human PSCs, and type I collagen were investigated in a series of tissue culture models. RESULTS: In vivo, the DR causes gross distortion of normal pancreas, bringing cancer cells into close contact with numerous PSCs and abundant type I collagen. In tissue culture models of pancreatic cancer, conditioned media from each cell line increased PSC [3H]thymidine incorporation up to 6.3-fold that of controls, and AsPC-1 cells also increased PSC collagen synthesis 1.3-fold. Type I collagen was observed to increase long-term survival of pancreatic cancer cells treated with 5-fluorouracil, by up to 62% in clonogenic assays. This was because type I collagen increased the proliferation of cancer cells ([3H]thymidine incorporation was up to 2.8-fold that of cells cultured on tissue culture plastic) and reduced apoptosis of AsPC-1 cells in response to 5-fluorouracil (by regulating mcl-1). CONCLUSIONS: These experiments elucidate a mechanism by which the DR in pancreatic cancer may form and, via the collagen within it, promote the malignant phenotype of pancreatic cancer cells, suggesting significant detriment to the host.     

Effects of 17 alpha-ethinylestradiol on sexual development of the amphipod Hyalella azteca

The effects of the synthetic estrogen 17alpha-ethinylestradiol (EE) on sexual development of the freshwater amphipod Hyalella azteca was investigated. Organisms were exposed in a multigeneration experiment to EE concentrations ranging from 0.1 to 10 microg/L and the development of both external and internal sexual characteristics were studied. Second-generation male H. azteca exposed from gametogenesis until adulthood to 0.1 and 0.32 microg EE/L developed significantly smaller second gnathopods. The sex ratio of the populations exposed to EE for more than two generations tended, although not statistically significantly, to be in favor of females. Histological aberrations of the reproductive tract, i.e., indications of hermaphroditism, disturbed maturation of the germ cells, and disturbed spermatogenesis, of post-F1-generation males were observed in all EE exposures. These findings provide evidence that sexual development of H. azteca is affected by exposure to sublethal concentrations of EE.     

A gene from the locus of enterocyte effacement that is required for enteropathogenic Escherichia coli to increase tight-junction permeability encodes a chaperone for EspF

Disruption of the barrier properties of the enterocyte tight junction is believed to be important in the pathogenesis of diarrhea caused by enteropathogenic Escherichia coli (EPEC). This phenotype can be measured in vitro as the ability of EPEC to reduce transepithelial resistance (TER) across enterocyte monolayers and requires the products of the locus of enterocyte effacement (LEE) and, in particular, the type III secreted effector protein EspF. We report a second LEE-encoded gene that is also necessary for EPEC to fully reduce TER. rorf10 is not necessary for EPEC adherence, EspADB secretion, or formation of attaching and effacing lesions. However, rorf10 mutants have a diminished TER phenotype, reduced intracellular levels of EspF, and a reduced ability to translocate EspF into epithelial cells. The product of rorf10 is a 14-kDa intracellular protein rich in alpha-helices that specifically interacts with EspF but not with Tir or other EPEC secreted proteins. These properties are consistent with the hypothesis that rorf10 encodes a type III secretion chaperone for EspF, and we rename this protein CesF, the chaperone for EPEC secreted protein F.     

Peroxisome biogenesis occurs in late dorsal-anterior structures in the development of Xenopus laevis.

Metabolism and development are two important processes not often examined in the same context. The focus of the present study is the expression of specific peroxisomal genes, the subsequent biogenesis of peroxisomes, and their potential role in the metabolism associated with the development of Xenopus laevis embryos. The temporal and expression patterns of six peroxisomal genes (PEX5, ACO, PEX19, PMP70, PEX16, and catalase) were elucidated using RT-PCR. Functionally related peroxisomal genes exhibited similar expression patterns with their RNA levels elevated relatively late during embryogenesis. Using immunohistochemistry PMP70 and catalase protein was localized largely to dorsal-anterior structures. Peroxisomal function was assayed with peroxisomal targeted-GFP, which when microinjected, revealed peroxisomes in dorsal-anterior structures at stage 45. A requirement for peroxisomal function appears to be present only late in development as organogenesis is finishing, yolk stores are depleted, and ingestion commences.     

Performance characteristics of updated INNO-LiPA assays for molecular typing of human leukocyte antigen A (HLA-A), HLA-B, and HLA-DQB1 alleles

We carried out a multicenter performance evaluation of three new DNA-based human leukocyte antigen (HLA) typing assays: INNO-LiPA HLA-A Update, INNO-LiPA HLA-B Update, and INNO-LiPA HLA-DQB1 Update. After optimization, the accuracy rates were all 100%, and the final observed resolutions were 99.4, 92.4, and 85.6%, respectively. These rapid and easy-to-perform assays yielded results fully concordant with other DNA-based tissue typing tests.     

Sensitivity and specificity of measures of the insomnia experience: a comparative study of psychophysiologic insomnia, insomnia associated with mental disorder and good sleepers

STUDY OBJECTIVES: To explore proposed explanatory mechanisms in psychophysiologic insomnia by investigating the sensitivity and specificity of commonly used insomnia research tools in discriminating psychophysiologic insomnia, insomnia associated with mental disorder, and good sleepers. DESIGN: Cross-sectional, between-group comparison of responses from subjects with psychophysiologic insomnia, those with insomnia associated with mental disorder, and good sleepers to psychometrically robust self-report instruments. SETTING: Attendees at adult community outpatient clinics. PARTICIPANTS: Fifty-four adults (36 women, 18 men; average age 40 years) across 3 groups (n = 18 per group). Participants with psychophysiologic insomnia met combined Inteernational Classification of Sleep Disorders, Revised and Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria and had no history of mental disorder. Participants with insomnia associated with mental disorder satisfied the same criteria for sleep disturbance and met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (Structured Clinical Interview for DSM-IV axis-I Disorders) criteria for depressive disorder. The majority had comorbid anxiety disorder. Insomnia duration in the groups with psychophysiologic insomnia and insomnia associated with mental disorder was around 10 years. Good sleepers served as a control group and included self-reported good sleepers with no history of sleep problems or psychiatric disorder. INTERVENTION: N/A. MEASUREMENTS AND RESULTS: Analyses of variance, adjusted for multiple comparisons, indicated no between-group differences on a measure of sleep-related stimulus control, and self-reported somatic arousal was higher in subjects with insomnia associated with mental disorder than in good sleepers or those with psychophysiologic insomnia. Subjects with insomnia associated with mental disorder and psychophysiologic insomnia had poorer sleep hygiene and were characterized by heightened mental arousal. Logistic regression indicated that "effortful preoccupation with sleep" discriminated subjects with both psychophysiologic insomnia (100% sensitivity, 94% specificity) and insomnia associated with mental disorder (100%, 100%) from good sleepers and that only depressive symptomatology discriminated insomnia associated with mental disorder from psychophysiologic insomnia. CONCLUSION: Psychophysiologic insomnia and insomnia associated with mental disorder may be on a continuum of insomnia severity, rather than categorically distinct. Insomnia associated with mental disorder may respond to psychological intervention. Factors specifically discriminating insomniacs from good sleepers require further investigation.     

Pathogenesis of Necrotizing Enterocolitis: Modeling the Innate Immune Response

Necrotizing enterocolitis (NEC) is a major cause of morbidity and mortality in premature infants. The pathophysiology is likely secondary to innate immune responses to intestinal microbiota by the premature infant''s intestinal tract, leading to inflammation and injury. This review provides an updated summary of the components of the innate immune system involved in NEC pathogenesis. In addition, we evaluate the animal models that have been used to study NEC with regard to the involvement of innate immune factors and histopathological changes as compared to those seen in infants with NEC. Finally, we discuss new approaches to studying NEC, including mathematical models of intestinal injury and the use of humanized mice.Necrotizing enterocolitis (NEC) is a disorder characterized by intestinal necrosis in premature infants that results in significant morbidity and mortality.¹ Approximately 7% of infants with a birth weight between 500 and 1500 g develop NEC.¹ The pathogenesis is characterized by intestinal inflammation that can progress to systemic infection/inflammation, multiorgan failure, and death. The bowel is distended and hemorrhagic on gross inspection. On microscopic examination, signs of inflammation, mucosal edema, epithelial regeneration, bacterial overgrowth, submucosal gas bubbles, and ischemic transmural necrosis are seen (Figure 1, A–E).²Open in a separate windowFigure 1Examples of the various grades of morphological damage in hematoxylin and eosin–stained specimens. A–E: Representative samples of premature infants with necrotizing enterocolitis. A: Age-matched control from patient with jejunal atresia. B: Mild injury with hemorrhagic necrosis of mucosa and loss of villus tip architecture. C: Progressive injury with inflammatory infiltration of muscularis with complete villus destruction. D: Severe muscular and epithelial damage with complete loss of mucosa. E: Perforation with transmural necrosis with complete loss of epithelial and muscular architecture. F–J: Representative samples from intestinal injury secondary to gavage feeding in the setting of hypothermia and hypoxia in neonatal rats. F: Intact morphology, grade 0. G: Sloughing of villus tips, grade 1. H: Mid-villus necrosis, grade 2. I: Loss of villi, grade 3. J: Complete destruction of the mucosa, grade 4. Insets in F–J show higher magnified portions of the same sections, corresponding to the boxed regions. K–O: Representative images of tissue injury secondary to 60 minutes of intestinal ischemia and 90 minutes of reperfusion in 2-week-old mice. K: Sham-operated mice (no ischemia). L: Villus tip necrosis. M: Mid-villus necrosis. N: Loss of villus architecture. O: Complete loss of mucosal architecture. F–J, reprinted with permission from Nature Publishing Group.²⁸ Scale bars = 50 μm (A–E, K–O). Original magnification, ×20 (A–O, main images, and F–J, insets).Currently the pathogenesis of NEC is believed to have multifactorial causes, including intestinal immaturity and microbial dysbiosis. Intestinal immaturity leads to a compromised intestinal epithelial barrier, an underdeveloped immune defense, and altered vascular development and tone. The compromised epithelial barrier and underdeveloped immune system, when exposed to luminal microbiota that have been shaped by formula feedings, antibiotic exposure, and Cesarean delivery, can lead to intestinal inflammation and sepsis. Despite therapeutic success in animal model systems, there are relatively few therapeutic strategies that have allowed for significantly improved outcomes in infants with NEC. Two hurdles that persist are our incomplete understanding of the developing immune system in premature infants and our inability to adequately replicate these complex factors in animal models.^3,4 This review summarizes the complex intestinal immune system in premature infants and details what is known about the involvement of innate immune factors in NEC, both in animal models and in human disease.