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6,077 result(s) for "Excretory system."
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My messy body
Explores the sometimes yucky functions of the body: why are vomit, pus, and snot sometimes good for us? And yes, pee and poo are also on the list.
The Caenorhabditis elegans Excretory System: A Model for Tubulogenesis, Cell Fate Specification, and Plasticity
The excretory system of the nematode Caenorhabditis elegans is a superb model of tubular organogenesis involving a minimum of cells. The system consists of just three unicellular tubes (canal, duct, and pore), a secretory gland, and two associated neurons. Just as in more complex organs, cells of the excretory system must first adopt specific identities and then coordinate diverse processes to form tubes of appropriate topology, shape, connectivity, and physiological function. The unicellular topology of excretory tubes, their varied and sometimes complex shapes, and the dynamic reprogramming of cell identity and remodeling of tube connectivity that occur during larval development are particularly fascinating features of this organ. The physiological roles of the excretory system in osmoregulation and other aspects of the animal's life cycle are only beginning to be explored. The cellular mechanisms and molecular pathways used to build and shape excretory tubes appear similar to those used in both unicellular and multicellular tubes in more complex organs, such as the vertebrate vascular system and kidney, making this simple organ system a useful model for understanding disease processes.
Visualization and 3D reconstruction of flame cells of Taenia solium (cestoda)
Flame cells are the terminal cells of protonephridial systems, which are part of the excretory systems of invertebrates. Although the knowledge of their biological role is incomplete, there is a consensus that these cells perform excretion/secretion activities. It has been suggested that the flame cells participate in the maintenance of the osmotic environment that the cestodes require to live inside their hosts. In live Platyhelminthes, by light microscopy, the cells appear beating their flames rapidly and, at the ultrastructural, the cells have a large body enclosing a tuft of cilia. Few studies have been performed to define the localization of the cytoskeletal proteins of these cells, and it is unclear how these proteins are involved in cell function. Parasites of two different developmental stages of T. solium were used: cysticerci recovered from naturally infected pigs and intestinal adults obtained from immunosuppressed and experimentally infected golden hamsters. Hamsters were fed viable cysticerci to recover adult parasites after one month of infection. In the present studies focusing on flame cells of cysticerci tissues was performed. Using several methods such as video, confocal and electron microscopy, in addition to computational analysis for reconstruction and modeling, we have provided a 3D visual rendition of the cytoskeletal architecture of Taenia solium flame cells. We consider that visual representations of cells open a new way for understanding the role of these cells in the excretory systems of Platyhelminths. After reconstruction, the observation of high resolution 3D images allowed for virtual observation of the interior composition of cells. A combination of microscopic images, computational reconstructions and 3D modeling of cells appears to be useful for inferring the cellular dynamics of the flame cell cytoskeleton.
REVIEW: Antimicrobial resistance in wildlife
The spread of antimicrobial resistance is of major concern for human health and leads to growing economic costs. While it is increasingly hypothesized that wildlife could play an important role in antimicrobial‐resistant bacteria dynamics, empirical data remain scarce. The present work builds on a systematic review of the available data in order to highlight the main information we have and to suggest research pathways that should be followed if we aim to fill the gaps in our current knowledge. To achieve this goal, we address four questions: (i) Which resistant bacteria are the most frequently observed in wildlife? (ii) How are resistant bacteria exchanged between wildlife and the other hosts involved? (iii) In which habitats are those resistant bacteria found? (iv) Are resistances associated with certain ecological traits of the host? Synthesis and applications. We highlight the strong link existing between the impact of human activities on natural habitats and the carriage of antimicrobial‐resistant bacteria by wildlife. Furthermore, we underline that omnivorous, anthropophilic and carnivorous species are at high risk of being carriers and potentially spreaders of antimicrobial‐resistant bacteria. Identifying among those groups key sentinel species may be of particular interest to implement ecosystem contamination surveillance. Finally, we discuss possible exchange routes for antimicrobial‐resistant bacteria between humans and wildlife. Considering that water is of major importance in those exchanges, a critical way to control antimicrobial resistance spread may be to limit aquatic environment contamination by antimicrobial‐resistant bacteria and antibiotics.
Deletion of the lactoperoxidase gene causes multisystem inflammation and tumors in mice
Abstract Strongly oxidative H 2 O 2 is biologically important, but if uncontrolled, would lead to tissue injuries. Lactoperoxidase (LPO) catalyzes the redox reaction of reducing highly reactive H 2 O 2 to H 2 O while oxidizing thiocyanate (SCN − ) to relatively tissue-innocuous hypothiocyanite (OSCN − ). SCN − is the only known natural, effective reducing-substrate of LPO; humans normally derive SCN − solely from food. While its enzymatic mechanism is understood, the actual biological role of the LPO-SCN − system in mammals remains unestablished. Our group previously showed that this system protected cultured human cells from H 2 O 2 -caused injuries, a basis for the hypothesis that general deficiency of such an antioxidative mechanism would lead to multisystem inflammation and tumors. To test this hypothesis, we globally deleted the Lpo gene in mice. The mutant mice exhibited inflammation and lesions in the cardiovascular, respiratory, digestive or excretory systems, neuropathology, and tumors, with high incidence. Thus, this understudied LPO-SCN − system is an essential protective mechanism in vivo.
Authors’ reply to Gallagher and Winocour
[...]the presence of an imbalance between the randomised groups necessitates further inquiry.
Uncomplicated Urinary Tract Infection
Nitrofurantoin, trimethoprim–sulfamethoxazole, fosfomycin, and pivmecillinam are considered first-line agents for cystitis. Fluoroquinolones should not be routine first-line choices for cystitis, although they are first-line empirical therapy for pyelonephritis. Foreword This Journal feature begins with a case vignette highlighting a common clinical problem. Evidence supporting various strategies is then presented, followed by a review of formal guidelines, when they exist. The article ends with the author's clinical recommendations. Stage A 30-year-old woman calls you to report a 2-day history of worsening dysuria and urinary urgency and frequency. She reports having no fever, chills, back pain, or vaginal irritation or discharge. One month ago, you treated her with a 3-day course of trimethoprim–sulfamethoxazole for presumptive cystitis, and her symptoms resolved. She is otherwise healthy, but this is her third episode in the past year. How should her case be managed? The Clinical Problem Incidence Urinary tract infection is the most common bacterial infection encountered in the ambulatory care setting in the United States, accounting for 8.6 million visits (84% . . .
Post-testicular sperm maturation in ancient holostean species
Fish speciation was accompanied by changes in the urogenital system anatomy. In evolutionarily modern Teleostei, male reproductive tracts are fully separated from the excretory system, while in evolutionarily ancient Chondrostei and Holostei, the excretory and reproductive tracts are not separated. Sturgeon post-testicular sperm maturation (PTSM) occurring as a result of sperm/urine mixing is phenomenologically well described, while, in holosteans, functional intimacy of seminal ducts with kidney ducts and the existence of PTSM still need to be addressed. In Lepisosteus platostomus (Holostei), sperm samples were collected from testes (TS), efferent ducts (EDS), and Wolffian ducts (WDS). While WDS was motile, no motility was found in TS and EDS. The existence of PTSM was checked by in vitro PTSM procedure. After TS and EDS incubation in seminal fluid from WDS, no more than 5% motile spermatozoa were observed in TS, whereas in EDS the motility percentage was up to 75%. Experimental dyeing of urogenital ducts in gars and sturgeons revealed some differences in the interconnection between sperm ducts and kidneys. It is concluded that post-testicular sperm maturation occurs in gars and suggests that infraclass Holostei occupies an intermediate evolutionary position between Teleostei and Chondrostei in the anatomical arrangement of the urogenital system.
Maternal and neonatal consequences of treated and untreated asymptomatic bacteriuria in pregnancy: a prospective cohort study with an embedded randomised controlled trial
Summary Background Existing approaches for the screening and treatment of asymptomatic bacteriuria in pregnancy are based on trials that were done more than 30 years ago. In this study, we reassessed the consequences of treated and untreated asymptomatic bacteriuria in pregnancy. Methods In this multicentre prospective cohort study with an embedded randomised controlled trial, we screened women (aged ≥18 years) at eight hospitals and five ultrasound centres in the Netherlands with a singleton pregnancy between 16 and 22 weeks' gestation for asymptomatic bacteriuria. Screening was done with a single dipslide and two culture media. Dipslides were judged positive when the colony concentration was at least 1×105 colony-forming units (CFU) per mL of a single microorganism or when two different colony types were present but one had a concentration of at least 1×105 CFU per mL. Asymptomatic bacteriuria-positive women were eligible to participate in the randomised controlled trial comparing nitrofurantoin with placebo treatment. In this trial, participants were randomly assigned 1:1 to receive either nitrofurantoin 100 mg or identical placebo tablets, and were instructed to self-administer these tablets twice daily for 5 consecutive days. Randomisation was done by a web-based application with a computer-generated list with random block sizes of two, four, or six participants rendered by an independent data manager. 1 week after the end of treatment, they provided us with a follow-up dipslide. Women, treating physicians, and researchers all remained unaware of the bacteriuria status and treatment allocation. Women who refused to participate in the randomised controlled trial did not receive any antibiotics, but their outcomes were collected for analysis in the cohort study. We compared untreated and placebo-treated asymptomatic bacteriuria-positive women with asymptomatic bacteriuria-negative women and nitrofurantoin-treated asymptomatic bacteriuria-positive women. The primary endpoint was a composite of pyelonephritis with or without preterm birth at less than 34 weeks, analysed by intention to treat at 6 weeks post-partum. This trial is registered with the Dutch Trial Registry, number NTR3068. Findings Between Oct 11, 2011, and June 10, 2013, we enrolled 5621 women into our screening cohort, of whom 5132 were eligible for screening. After exclusions for contaminated dipslides and patients lost to follow-up, in our final cohort of 4283 women, 248 were asymptomatic bacteriuria positive, of whom 40 were randomly assigned to nitrofurantoin and 45 to placebo for the randomised controlled trial, whereas the other 163 asymptomatic bacteriuria-positive women were followed without treatment. The proportion of women with pyelonephritis, preterm birth, or both did not differ between untreated or placebo-treated asymptomatic bacteriuria-positive women and asymptomatic bacteriuria-negative women (6 [2·9%] of 208 vs 77 [1·9%] of 4035; adjusted odds ratio [OR] 1·5, 95% CI 0·6–3·5) nor between asymptomatic bacteriuria-positive women treated with nitrofurantoin versus those who were untreated or received placebo (1 [2·5%] of 40 vs 6 [2·9%] of 208; risk difference −0·4, 95% CI −3·6 to 9·4). Untreated or placebo-treated asymptomatic bacteriuria-positive women developed pyelonephritis in five [2·4%] of 208 cases, compared with 24 [0·6%] of 4035 asymptomatic bacteriuria-negative women (adjusted OR 3·9, 95% CI 1·4–11·4). Interpretation In women with an uncomplicated singleton pregnancy, asymptomatic bacteriuria is not associated with preterm birth. Asymptomatic bacteriuria showed a significant association with pyelonephritis, but the absolute risk of pyelonephritis in untreated asymptomatic bacteriuria is low. These findings question a routine screen-treat-policy for asymptomatic bacteriuria in pregnancy. Funding ZonMw (the Netherlands Organisation for Health Research and Development).
Pioglitazone use and risk of bladder cancer: population based cohort study
Objective To determine whether pioglitazone compared with other antidiabetic drugs is associated with an increased risk of bladder cancer in people with type 2 diabetes.Design Population based cohort study.Setting General practices contributing data to the United Kingdom Clinical Practice Research Datalink.Participants A cohort of 145 806 patients newly treated with antidiabetic drugs between 1 January 2000 and 31 July 2013, with follow-up until 31 July 2014.Main outcome measures The use of pioglitazone was treated as a time varying variable, with use lagged by one year for latency purposes. Cox proportional hazards models were used to estimate adjusted hazard ratios with 95% confidence intervals of incident bladder cancer associated with pioglitazone overall and by both cumulative duration of use and cumulative dose. Similar analyses were conducted for rosiglitazone, a thiazolidinedione not previously associated with an increased risk of bladder cancer.Results The cohort generated 689 616 person years of follow-up, during which 622 patients were newly diagnosed as having bladder cancer (crude incidence 90.2 per 100 000 person years). Compared with other antidiabetic drugs, pioglitazone was associated with an increased risk of bladder cancer (121.0 v 88.9 per 100 000 person years; hazard ratio 1.63, 95% confidence interval 1.22 to 2.19). Conversely, rosiglitazone was not associated with an increased risk of bladder cancer (86.2 v 88.9 per 100 000 person years; 1.10, 0.83 to 1.47). Duration-response and dose-response relations were observed for pioglitazone but not for rosiglitazone.Conclusion The results of this large population based study indicate that pioglitazone is associated with an increased risk of bladder cancer. The absence of an association with rosiglitazone suggests that the increased risk is drug specific and not a class effect.