Brief Period Of Exposure Research Articles

Biochemical and physiological alterations caused by Diuron and Triclosan in mussels (Mytilus galloprovincialis)

The rise in the utilization of pesticides within industrial and agricultural practices has been linked to the occurrence of these substances in aquatic environments. The objective of this work was to evaluate the uptake and adverse impacts of Diuron (Di) and Triclosan (TCS) on the mussel species Mytilus galloprovincialis. To accomplish this, the accumulation and toxicity of these pesticides were gauged following a brief period of exposure spanning 14 days, during which the mussels were subjected to two concentrations (50 and 100 μg/L) of each substance that are ecologically relevant. Chemical analysis of Di and TCS within gills and digestive gland showed that these pesticides could be accumulated in mussel's tissues. In addition, Di and TCS are preferably accumulated in digestive gland.Measured biomarkers included physiological parameters (filtration FC and respiration RC capacity), antioxidant enzyme activities (superoxide dismutase and catalase), oxidative damage indicator (Malondialdheyde concentration) and neurotoxicity level (acetylcholinesterase activity) were evaluated in gills and digestive glands. Both pesticides were capable of altering the physiology of this species by reducing the FC and RC in concentration and chemical dependent manner. Both pesticides induced also an oxidative imbalance causing oxidative stress. The high considered concentration exceeded the antioxidant defense capacity of the mussel and lead to membrane lipid peroxidation that resulted in cell damage. Finally, the two pesticides tested were capable of interacting with the neuromuscular barrier leading to neurotoxicity in mussel's tissues by inhibiting acetylcholinesterase. The ecotoxicological effect depended on the concentration and the chemical nature of the contaminant. Obtained results revealed also that the Di may exert toxic effects on M. galloprovincialis even at relatively low concentrations compared to TCS.In conclusion, this study presents innovative insights into the possible risks posed by Diuron (Di) and Triclosan (TCS) to the marine ecosystem. Moreover, it contributes essential data to the toxicological database necessary for developing proactive environmental protection measures.

A muscle growth-promoting treatment based on the attenuation of activin/myostatin signalling results in long-term testicular abnormalities.

ABSTRACTActivin/myostatin signalling acts to induce skeletal muscle atrophy in adult mammals by inhibiting protein synthesis as well as promoting protein and organelle turnover. Numerous strategies have been successfully developed to attenuate the signalling properties of these molecules, which result in augmenting muscle growth. However, these molecules, in particular activin, play major roles in tissue homeostasis in numerous organs of the mammalian body. We have recently shown that although the attenuation of activin/myostatin results in robust muscle growth, it also has a detrimental impact on the testis. Here, we aimed to discover the long-term consequences of a brief period of exposure to muscle growth-promoting molecules in the testis. We demonstrate that muscle hypertrophy promoted by a soluble activin type IIB ligand trap (sActRIIB) is a short-lived phenomenon. In stark contrast, short-term treatment with sActRIIB results in immediate impact on the testis, which persists after the sessions of the intervention. Gene array analysis identified an expansion in aberrant gene expression over time in the testis, initiated by a brief exposure to muscle growth-promoting molecules. The impact on the testis results in decreased organ size as well as quantitative and qualitative impact on sperm. Finally, we have used a drug-repurposing strategy to exploit the gene expression data to identify a compound – N6-methyladenosine – that may protect the testis from the impact of the muscle growth-promoting regime. This work indicates the potential long-term harmful effects of strategies aimed at promoting muscle growth by attenuating activin/myostatin signalling. Furthermore, we have identified a molecule that could, in the future, be used to overcome the detrimental impact of sActRIIB treatment on the testis.

Rapid adaptation to foreign-accented speech and its transfer to an unfamiliar talker.

How fast can listeners adapt to unfamiliar foreign accents? Clarke and Garrett [J. Acoust. Soc. Am. 116, 3647-3658 (2004)] (CG04) reported that native-English listeners adapted to foreign-accented English within a minute, demonstrating improved processing of spoken words. In two web-based experiments that closely follow the design of CG04, the effects of rapid accent adaptation are examined and its generalization is explored across talkers. Experiment 1 replicated the core finding of CG04 that initial perceptual difficulty with foreign-accented speech can be attenuated rapidly by a brief period of exposure to an accented talker. Importantly, listeners showed both faster (replicating CG04) and more accurate (extending CG04) comprehension of this talker. Experiment 2 revealed evidence that such adaptation transferred to a different talker of a same accent. These results highlight the rapidity of short-term accent adaptation and raise new questions about the underlying mechanism. It is suggested that the web-based paradigm provides a useful tool for investigations in speech adaptation.

P16 ‐ A child with solar urticaria

Solar urticaria is a rare photodermatosis characterized by pruritus, stinging, erythema, and wheal formation after a brief period of exposure to natural sunlight or an artificial light source emitting the appropriate wavelength. Herein, we present a Turkish boy with solar urticaria.

Manipulation of the Microbiota for Treatment of IBS and IBD—Challenges and Controversies

There is compelling rationale for manipulating the microbiota to treat inflammatory bowel diseases (IBDs). Although studies of animal models of intestinal inflammation produced promising results, trials in humans have been disappointing. In contrast to IBD, the role of the microbiota in the development of irritable bowel syndrome (IBS) only recently has been considered, but early stage results have been encouraging. As pharmaceutical companies develop fewer truly novel agents for treatment of these disorders, consumers seek safer, long-term strategies to deal with chronic symptoms. We assess the rationale for modulating the microbiota for treatment of IBD and IBS, and discuss whether current concepts are simplistic and overstated or simply under-researched. Are claims exaggerated and expectations unrealistic? Difficulties with microbiota terminology and technologies, as well as differences among patients and the heterogeneity of these diseases, pose additional challenges in developing microbiota-based therapies for IBD and IBS.

Lithographus, an Abundant Arthropod Trackway from the Cretaceous Haenam Tracksite of Korea

Trackways ascribed to Lithographus hieroglypichus and attributed to pterygote insects are described from the Cretaceous Uhangri Formation of Korea. The locality is part of the Haenam Tracksite at the Uhangri Dinosaur Museum Complex, which is famous for dinosaur, pterosaur and bird tracks. This represents the first report of the arthropod trackway Lithographus from the Cretaceous of Korea. The trackways are preserved in cherty mudstones that formed in the margins of an alkaline lake in the vicinity of active volcanoes. Numerous trackways are preserved at a single horizon. This probably reflects a brief period of exposure of balanced-fill lake margin sediments, which provided a window of opportunity for the production and preservation of trackways of insects that inhabited the region rather than a sudden influx of insects into the area related to volcanism and a productivity bloom.

Solar urticaria treated successfully with intravenous high‐dose immunoglobulin: a case report

Solar urticaria is an idiopathic, chronic and rare photodermatosis, characterized by the sudden onset of pruritic urticarial hives and plaques on the exposed areas of the skin, after a brief period of exposure to the natural sunlight or to an artificial light source. A Caucasian 27-year-old man presented with clinical features suggestive of solar urticaria was referred to our photodermatology unit, where phototesting confirmed the diagnosis of solar urticaria induced by visible light. As he was refractory to oral antihistamines and had slight improvement under UVA plus visible phototherapy, human high-dose intravenous immunoglobulin was administered, with an excellent clinical-sustained response.

In vitro effects of ethanol on the phagocytic and microbial killing activities of normal human monocytes and monocyte-derived macrophages.

Human blood monocytes were cultured within the wells of chamber slides in growth medium to which 0, 1, 2, or 3 mg ethanol per ml was added at the start of the culture. After incubation for 1 h, 1 day and 7 days, their ability to phagocytoze IgG-sensitized red cells and to phagocytoze and kill non-opsonized Candida albicans was assessed. In all alcohol-containing wells, the concentration of alcohol in the growth medium fell progressively, reaching negligible values after 3 days. When compared with control cells, monocytes incubated with 1, 2 or 3 mg ethanol/mg for 1 h showed impaired phagocytosis of IgG-sensitized RBC and non-opsonized C. albicans and those incubated with 1 or 2 mg ethanol/ml for 1 h showed impaired killing of Candida. After incubation for 7 days, the monocyte-derived macrophages in wells initially containing 1, 2 or 3 mg ethanol/ml showed increased phagocytic activity towards C. albicans but not towards sensitized RBC. In addition, in 4 of 5 experiments, the percentage of phagocytozed organisms killed was increased in wells initially containing 1 mg ethanol/ml. The results support the view that the susceptibility of chronic alcoholics to certain infections may be partly dependent on an ethanol-induced depression of the phagocytic and killing functions of macrophages. They also suggest that a few days after a brief period of exposure to ethanol there may be stimulation of certain but not all effector functions of macrophages.

Effect of budesonide and montelukast in asthmatic children exposed to relevant allergens

Montelukast has been shown to be effective in controlling the increase in exhaled NO in asthmatic children re-exposed to house dust mite (HDM). This study compared the effect of low dose inhaled budesonide and oral montelukast in preventing the expected relapse of airway inflammation and reactivity in a group of 24 mild asthmatic children allergic to HDM after a brief period of exposure to relevant allergens. Lung function, bronchial hyperresponsiveness (BHR) to methacholine (PC(20)), fractional exhaled nitric oxide (FeNO) levels and sputum eosinophilia were evaluated. Pulmonary function remained stable. The BHR was unchanged after exposure in the group treated with budesonide, whereas a significant increase (P = 0.028) was observed in the patients receiving montelukast. No significant difference was observed in FeNO levels after exposure to mite antigen in the two groups. In both the groups of asthmatic children we observed a significant increase in sputum eosinophil % after the exposure to mite antigen. The significant increase in BHR level observed in the group of children receiving montelukast suggests a more comprehensive effect as disease controller by inhaled steroids than by leukotriene antagonist in allergic asthmatic children re-exposed to relevant allergens.

The spatial and temporal conditions for perceiving velocity as constant.

Perceived velocities during a brief period of exposure (< 1.2 s) were measured to examine how much time is necessary to perceive velocity as constant. Moving sinusoidal gratings were used as stimuli at relatively low velocities. At the beginning of each stimulus presentation, a moving pattern was perceived as stationary until a critical time had passed. After that, perceived velocity was positively correlated with moving distance, irrespective of physical velocity below a critical moving distance. Beyond the critical moving distance, velocity was perceived as constant. A simple model is presented to explain these results.

Short-term exposure of Chinook salmon (Oncoryhnchus tshawytscha) to o,p-DDE or DMSO during early life-history stages causes long-term humoral immunosuppression.

We evaluated the effect of short-term exposures to a xenobiotic chemical during early life-history stages on the long-term immune competence of chinook salmon (Oncoryhnchus tshawytscha). Immersion of chinook salmon eggs in a nominal concentration of o,p-dichlorodiphenyldichloroethylene (o,p-DDE; 10 ppm) for 1 hr at fertilization followed by immersion in the same dose for 2 hr at hatch resulted in a significant reduction in the ability of splenic leukocytes from fish 1 year after treatment to undergo blastogenesis upon in vitro stimulation with lipopolysaccharide. We also observed that the vehicle, dimethyl sulfoxide (DMSO), caused a significant reduction in the ability of the splenic leukocytes to express surface immunoglobin M (SIgM) at this time. The concentration of o,p-DDE in a pooled sample of whole fry from this treatment was 0.53 microg/g lipid 1 month after first feeding but was undetectable in all other treatments. Mortality rate, time to hatch, fish length, and weight were unaffected by treatment with o,p-DDE. Similarly, sex ratios, gonadal development, and concentrations of plasma estradiol and 11-ketotestosterone were not affected by the treatment. In addition, we found no evidence that plasma lysozyme concentrations or the mitogenic responses of splenic leukocytes to concanavalin A or polyinosinic-polycytidylic acid were influenced by the treatment. In this experiment, a brief period of exposure to o,p-DDE or DMSO during early development was able to induce long-term effects on humoral immune competence of chinook salmon. Such immunosuppression may increase susceptibility to disease, which may in turn be critical to regulating the population.

Effects of amisulpride on consummatory negative contrast.

Two groups of rats, 'shifted' (32-4% sucrose) and 'unshifted' (4-4% sucrose), were given access to sucrose solutions for 5 min/day for 10 days. On day 11, shifted animals had access to a devalued incentive (4% sucrose) and subgroups of each group received doses of amisulpride (10 or 60 mg/kg, i.p.) or its vehicle before a 10-min access period to sucrose solutions. Lick frequency was measured both pre- and post-shift. A high dose of amisulpride reduced successive negative contrast (SNC) after a brief period of exposure to the devalued stimulus, whereas a low dose had no effect. The acute effects of high doses of amisulpride seem to act on contrast effects in a similar way to anxiolytic compounds such as the benzodiazepine, chlordiazepoxide.

Conglutinin acts as an opsonin for influenza A viruses.

Since the 1940's, non-Ig inhibitors of influenza A virus (IAV) hemagglutination activity and infectivity have been recognized in mammalian sera. Recently, the heat labile (beta) inhibitor of this type was identified by indirect methods as the lectin, conglutinin. In support of this hypothesis, we found that purified conglutinin strongly inhibited hemagglutination activity and infectivity of IAV. By using IAV strains with specific variations in glycosylation of the hemagglutinin molecule, we showed these effects to be mediated by binding of conglutinin to high mannose carbohydrate attachments on the viral hemagglutinin. Through the same mechanism conglutinin caused aggregation of IAV particles. Human neutrophils produce hydrogen peroxide upon exposure to IAV. Also, after a brief period of exposure to IAV, neutrophils exhibit depressed responsiveness (deactivation) upon exposure to other stimuli (e.g., chemotactic peptides). These phenomena may be related to the in vivo inflammatory response during IAV infection, and to the propensity of IAV-infected subjects to suffer bacterial superinfection. Pre-incubation of IAV with conglutinin markedly potentiated human neutrophil hydrogen peroxide production in response to the virus. This effect correlated with the ability of conglutinin to aggregate the virus. IAV treated with conglutinin also caused significantly less neutrophil deactivation than did the unopsonized virus. These enhancements of neutrophil respiratory burst responses by conglutinin were again mediated by binding of the lectin to viral carbohydrates. The mammalian C-type lectin family includes conglutinin, mannose-binding protein, and surfactant proteins A and D. These lectins may be important constituents of the initial host response to IAV, by inhibiting IAV infectivity directly, causing viral aggregation, and acting as opsonins to enhance phagocyte responses to the virus.

Short-term exposure to an odor increases its subsequent preference in preweanling rats: a descriptive profile of the phenomenon.

Five experiments assessed the change in preference for an ambient odor after a brief period of exposure to that odor. Three minutes of exposure to a novel odor consistently increased subsequent preference for that odor. This effect occurred in preweanling rats 10 and 15 days of age even though, relative to the nest, the conditions of exposure were probably aversive tactually and thermally. There was relatively little variation in this effect between the ages of 10 Days postnatal and adulthood and over exposure durations ranging between 3 and 81 min. Substantial retention of this exposure effect was found for the 10-day-old rat, with no decline in induced preference over a 24-hr period. The effect was unchanged by brief familiarization with the testing situation, but was eliminated by prior aversive experience with the testing situation. These results have implications for the design and interpretation of experiments that test learning and memory of odors, and emphasize generally the facility of the developing rat for processing olfactory information.

Assessment of timed bacteriostatic and bactericidal activities of cephalothin against gram-positive and gram-negative bacteria.

The comparative bacteriostatic and bactericidal activities of cephalothin were assessed in broth medium with special reference to the period of exposure of microbes to the drug. The bacteriostatic concentration with a brief period of exposure (6 h) was lower than the conventional MIC for Escherichia coli and Klebsiella sp. When the period of exposure was prolonged (18-42 h), the bacteriostatic concentration almost corresponded with the MIC. In contrast to these gram-negatives, the bacteriostatic concentration with a brief period of exposure roughly corresponded with the MIC for strains of Staphylococcus aureus and was higher for enterococcus. When a comparison of the bacteriostatic and the bactericidal concentrations was used as the criterion for assessment, the mode of action of cephalothin appeared to be bactericidal to most of the gram-negatives. This drug was bacteriostatic to a number of strains of gram-positives, in particular to enterococcus, especially when microbes were exposed to the drug over a brief period of time.

Adriamycin-induced changes in the surface membrane of sarcoma 180 ascites cells

Adriamycin increases (a) the rate of agglutination of Sarcoma 180 cells by concanavalin A after brief exposure of 2–3 h and (b) membrane fluidity as measured by ESR within 30 min of exposure at concentrations of the anthracycline of 10 −7–10 −5 M. The effect of adriamycin on agglutination is not due to an increase in the number of surface receptors for concanavalin A, since the extent of binding of the lectin is not altered by adriamycin and no change occurs in the rate of occupancy of the concanavalin A binding sites by the lectin in cells treated with the antibiotic. The order parameter, a measurement of membrane fluidity, decreases in cells exposed to adriamycin and is dose-related. The results indicate that adriamycin can induce changes in the surface membrane of Sarcoma 180 cells within a brief period of exposure to a low but cytotoxic level of this agent.

The role of HLA-DR determinants in monocyte-macrophage presentation of herpes simplex virus antigen to human T cells

The ability of a monomorphic monoclonal anti-HLA-DR antibody to block herpes simplex virus antigen-induced lymphocyte proliferation was assessed using three in vitro cell systems: peripheral blood mononuclear cells (PBMC); separated monocytes (Mo) added to enriched T-cell populations; and macrophages (Mφ) cultured in vitro in microtiter wells 7 to 10 days prior to pulsing with antigen and the addition of T cells. Inhibition of transformation with PBMC was inconsistent and was not improved by varying the cell numbers, antigen dose, or antibody dilution. Under appropriate conditions, blocking was seen in the Mo, T-cell cultures with monoclonal antibody but this reagent appeared to be less potent than alloanti-DR sera. Blocking of the mixed lymphocyte reaction was also seen with the monoclonal reagent at low numbers of irradiated PBMC or Mo stimulator cells. In vitro-activated macrophages were capable of supporting HSV-induced proliferation and augmenting PHA-induced proliferation with kinetics similar to that seen with the standard PBMC assay. Mφ were able to stimulate T cells after a brief period of exposure to antigen and this proliferative response was also weakly blocked by allo-anti-DR but not by monomorphic, monoclonal antibody.

Megakaryocytopoiesis in culture: modulation by cholinergic mechanisms.

Treatment of murine bone marrow cultures with the cholinergic agonist carbamylcholine enhanced megakaryocytic colony growth by as much as 65%. In contrast, adrenergic agonists had no such effect. Addition to cultures of dibutyryl cyclic GMP (db-cGMP) also enhanced megakaryocytic colonies up to 50%, whereas dibutyryl cyclic AMP (db-cAMP) had no effect. Sodium nitroprusside and sodium nitrite, putative guanyl cyclase activators, also enhanced colony numbers, as did imidazole, a postulated cGMP phosphodiesterase inhibitor. Preincubation of marrow for two hours with carbamylcholine resulted both an increase in colony numbers (58%) and percent of progenitors in DNA synthesis (48%, compared to 14% for controls) as determined by tritiated thymidine suicide studies. Treatment of mice with the acetylcholinesterase inhibitor neostigmine resulted in an increase in CFU-M/humerus (62%) and percent in DNA synthesis (45%). These data indicate that 1) cholinergic, but not adrenergic, agonists modulate megakaryocytopoiesis in culture; 2) this effect may be mediated by cyclic GMP; and 3) only a brief period of exposure of marrow cells to agonist results in enhancement of megakaryocytic colonies.

Pancreatic acinar cells: the effect of carbon dioxide, ammonium chloride and acetylcholine on intercellular communication.

1. Segments of mouse pancreatic or exorbital lacrimal gland were superfused with saline solutions. Under visual control two micro-electrodes were inserted into neighbouring cells within the same acinus or into neighbouring acini. Cell to cell electrical coupling was assessed by injecting rectangular current pulses through one electrode and measuring the electrotonic potential change in the same cell (V(1)) and in the neighbouring cell (V(2)). Acetylcholine (ACh) was added locally to impaled acini by micro-ionophoresis from an extracellular micropipette.2. Exposure of the tissues to a Krebs solution equilibrated with 100% CO(2) caused a rapid increase in the size of electrotonic potential changes in the current injection cell and disappearance of the electrotonic potential changes in a neighbouring acinus or cell. This electrical uncoupling of previously coupled cells was rapidly reversible upon return to a solution equilibrated with 95% O(2) and 5% CO(2).3. Reduction of electrical intercellular coupling was also obtained using smaller CO(2) concentrations (50, 20 or 10%). In these cases the effects developed more slowly and were less dramatic. Reducing the extracellular HCO(3) concentration enhanced the uncoupling effect of 10 or 20% CO(2). However, weak uncoupling effects were still observed using 10 or 20% CO(2) in combination with a high bicarbonate concentration maintaining a constant extracellular pH (7.4).4. Reductions in extracellular pH (down to 5.5) achieved by varying combinations of Tris base and Tris HCl had no effect on electrical coupling. Brief periods of anoxia (100% N(2)) also had no effect.5. Exposure to 20% CO(2) markedly enhanced the uncoupling effect of a brief ionophoretic pulse of ACh.6. Exposure of the tissue to 10 mM-NH(4)Cl, a procedure expected to increase the intracellular pH, counteracted the uncoupling effect of ACh. During sustained uncoupling caused by a sustained ACh stimulation a brief period of exposure to NH(4)Cl caused an immediate and fully reversible recoupling.7. It is concluded that variations in intracellular pH have marked effects on the electrical coupling between neighbouring cells in the pancreatic and lacrimal acinar tissue.

Effects of dietary fish oil on the composition and stability of turkey depot fat.

1. Beef fat (2.5%) and anchovy oil (2.5%; 2.5% plus 0.02% ethoxyquin; 5%) were incorporated into isocaloric cereal-based diets A, B, C and D and given to turkeys from 2 to 10 weeks of age. Diets A, B, and C contained 13 and diet D 26 i.u. α-tocopheryl acetate/kg. The lipids of diets B and D, which contained fish oil without ethoxyquin, autoxidized in the feeding troughs, but not seriously in the brief period of exposure permitted. 2. The birds all remained healthy and grew well, the only nutritional effects of the fish oil being a depressed storage of vitamin A in the liver at both levels of feeding (prevented by ethoxyquin) and a slightly adverse effect, at the higher level only, on food conversion ratio. 3. The skin fats of the birds given fish oil contained seven major and two minor fatty acids, derived from the fish oil, which were not present in the skin of the control group given beef fat, as well as one major fish oil acid present in much greater concentration in the birds given fish oil than in the controls. All these acids were present in the skin fats at about half or two-thirds of their concentrations in the dietary lipid, except for acid 22:5, which reached two or three times this level. 4. The stabilities towards autoxidation of the skin fats decreased in the order A &gt; C &gt; B &gt; D, as their content of polyunsaturated fatty acids increased, but the greater stability of group C as compared with B was probably due, in the main, to the higher tocopherol content of the skin fat of the birds on the ethoxyquin-containing diet. Fishy flavours which developed on cooking showed a similar relationship to diet.