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Experimental Groups (experimental + groups)
Selected AbstractsIntersensory redundancy educates selective attention in bobwhite quail embryosDEVELOPMENTAL SCIENCE, Issue 6 2006Robert Lickliter We assessed whether exposure to amodal properties in bimodal stimulation (e.g. rhythm, rate, duration) could educate attention to amodal properties in subsequent unimodal stimulation during prenatal development. Bobwhite quail embryos were exposed to an individual bobwhite maternal call under several experimental and control conditions during the day prior to hatching. Experimental groups received redundant auditory and visual exposure to the temporal features of an individual maternal call followed by unimodal auditory exposure to the same call immediately or after a 2-hr or 4-hr delay. Control groups received (1) the same exposure but in the reverse sequence (unimodal , redundant bimodal), (2) asynchronous bimodal , unimodal, (3) only unimodal exposure, or (4) only bimodal exposure. All experimental groups showed a significant preference for the familiar maternal call over a novel maternal call when tested 2 days after hatching, whereas none of the control groups showed a significant preference for the familiar call. These results indicate that intersensory redundancy can direct attention to amodal properties in bimodal stimulation and educate attention to the same amodal properties in subsequent unimodal stimulation where no intersensory redundancy is available. [source] Vascular alterations in the rabbit patellar tendon after surgical incisionJOURNAL OF ANATOMY, Issue 5 2001M. R. DOSCHAK Open incision of the patellar tendon (PT) is thought to promote acute vascular responses which ultimately result in an enhanced degree of tendon repair. Such a clinical procedure is commonly applied to patients with refractory tendinitis. The objective of this study was to quantify the vascular adaptations (both anatomical and physiological) to longitudinal incision of the PT, and the resultant effects on tendon organisation. Fifty-four New Zealand White rabbits were separated into 3 experimental groups and 2 control groups. Experimental groups underwent surgical incision of the right PT, and were assessed 3 d, 10 d and 42 d following injury; normal unoperated controls were evaluated at time zero, and sham-operated controls were evaluated at 3 d to control for the effects of incising the overlying skin. Quantitative measures of PT blood supply (blood flow, microvascular volume) and geometric properties of PT substance were obtained for each PT. Histomorphology was assessed to evaluate vascular remodelling and matrix organisation in the healing PT. Longitudinal open incision surgery of the PT led to rapid increases in both blood flow and vascular volume. The incision of overlying tissues alone (sham-operated) contributed to this measurable increase, and accounted for 36% and 42% of the elevated blood flow and vascular volume respectively at the 3 d interval. In the incised PT, blood flow significantly increased by 3 d compared with both time zero and sham-operated controls, and remained significantly elevated at the 10 d interval. Similarly, vascular volume of the incised PT increased at 3 d compared both with time zero and sham-operated controls. At the 10 d interval, the increase in vascular volume was greatest in the central PT substance. By 42 d both blood flow and vascular volume of the incised tendon had diminished, with only blood flow remaining significantly different from controls. In the contralateral limb, a significant neurogenically mediated vasodilation was measured in the contralateral PTs at both early time intervals, but was not seen by the later 42 d interval. With respect to PT geometric properties in the experimental animals, a larger PT results as the tendon matrix and blood vessels remodel. PT cross-sectional area increased rapidly by 3 d to 1·3 times control values, and remained significantly elevated at 42 d postinjury. Morphological assessments demonstrated the disruption of matrix organisation by vascular and soft tissue components associated with the longitudinal incisions. Substantial changes in matrix organisation persisted at 42 d after surgery. These findings suggest that open longitudinal incision of the PT increases the vascular supply to deep tendon early after injury. These changes probably arise through both vasomotor and angiogenic activity in the tissue. Since PT blood flow and vascular volume return towards control levels after 6 wk but structural features remain disorganised, we propose that vascular remodelling is more rapid and complete than matrix remodelling after surgical incision of the PT. [source] Strain differences in autotomy in mice after peripheral nerve transection or repairMICROSURGERY, Issue 4 2003Roee E. Rubinstein A.B. The purpose of this study was to identify the optimal murine model for the study of peripheral nerve injury and nerve and limb transplantation. The degree of self-mutilation (autotomy) following sciatic and saphenous nerve injury was assessed in four mouse strains, Balb/C, C57BL/6J, C57BL/10J, and C3HEB, commonly used in surgical research. Experimental groups included sciatic and saphenous nerve transection with repair (n = 9) or without repair (n = 9), as well as housing arrangements favoring social interaction vs. isolation. Autotomy was most prevalent in the Balb/c and C3H strains at 56% and 89% overall, respectively, and was much less frequently seen in the C57Bl/10 and C57Bl/6 strains (22% and 11%, respectively). Autotomy was found to correlate most strongly with mouse strain, and with social contact as well. Two strains, C57BL/6J and C57BL/10J, were found to be highly resistant to self-mutilation, and are thus ideal animal models for peripheral-nerve and whole-limb transplant studies. © 2003 Wiley-Liss, Inc. MICROSURGERY 23:363,368 2003 [source] Effect of Inhibitor of Tumor Necrosis Factor-, and Oxatomide on Immune Mediated Otitis MediaTHE LARYNGOSCOPE, Issue 9 2006Yong-Soo Park MD Abstract Objective: Inflammatory mediators (IMs) play a major role in the production of middle ear effusion (MEE). Tumor necrosis factor (TNF)-, and leukotrienes (LTs) appear to be important in the pathogenesis of otitis media with effusion (OME). The purpose of this study is to determine the effect of TNF-, and LT antagonist on the outcome of experimental immune-mediated OME. Study Design: Prospective. Methods: Otitis media was induced in rats by injecting keyhole limpet hemocyanin (KLH) transtympanically 7 days after systemic immunization. Experimental groups were treated with soluble TNF receptor type I (sTNF RI) or oxatomide simultaneously. Seventy-two hours after transtympanic injection, MEE was aspirated, and temporal bone was taken. Vascular permeability (VP) of the middle ear mucosa was measured using the Evans blue dye technique. Hematoxylin-eosin stain and immunohistochemical stain for leukocyte common antigen was performed. Results: In KLH, sTNF RI, and oxatomide groups, MEE was developed in 83%, 0%, and 66% of the ears, respectively. The sTNF RI group showed significant decrease in effusion production, inflammation, mucosal thickening, and VP compared with the KLH group. These parameters were less significant in the oxatomide group than in the sTNF RI group. Conclusion: Transtympanic administration of sTNF RI and oxatomide appears to suppress the development of immune-mediated MEE. [source] Toxic effects of dexamethasone on mouse testicular germ cellsANDROLOGIA, Issue 4 2010M. Orazizadeh Summary Exposure to glucocorticoids (GCs) leads to numerous changes in various biological systems including the reproductive system. This work evaluated effects of dexamethasone (Dex), a widely used GC, on mouse testicular germ cells. Experimental groups (E1,E3) received one of the following treatments daily for 7 days: 4, 7 and 10 mg kg,1 Dex respectively. Control groups were treated with equivalent volumes of saline. Testicular histopathology, morphometric analysis and deoxy-UTP-digoxigenin nick end labeling (TUNEL) assessment were performed for evaluation of the toxic effects of Dex and detection of the apoptotic cells. The results showed that Dex induces histopathological alterations such as epithelial vacuolisation, atrophy and reduction in testicular spermatozoid. Morphometrical data showed that Dex significantly reduced tubular diameter and epithelial height (P < 0.05). Johnsen's scoring also showed poor spermatogenesis in E2 and E3 groups (P < 0.05). Apoptotic index of germ cells was significantly increased in E2 (18.9% versus 1.76%, P < 0.01) and E3 (24.6 versus 1.76%, P < 0.001) groups. It is concluded that Dex acts as testicular toxicant and that further studies are needed to establish its mechanism of action upon spermatogenesis. [source] Immunological Response to (1,4)-,- d -Glucan in the Lung and Spleen of Endotoxin-Stimulated Juvenile RatsBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 5 2009Ectis A. Velazquez Experimental groups (n = 16/group) included controls with an intraperitoneal injection of saline, endotoxaemic rats with a non-lethal dose of 10 mg/kg Escherichia coli endotoxin, and endotoxaemic rats treated with two doses of 10 mg/kg ,-DG, intraperitoneally, 2 and 4 hr after endotoxin injection. At 24 hr of treatment, rats were euthanized and lungs and spleen were removed for cytokines determination and lung injury. Endotoxaemia increased IL-1, concentration by fivefold in both organs, while creating a moderate pulmonary hypercellularity (demonstrated by about 11% increase in the alveolar-septal thickening and 11% decrease in the alveolar-interstitial space ratio). In the lung, ,-DG treatment reduced concentrations of IL-1, by 30% (p > 0.05), IL-6 by 43% (p < 0.01), IFN-, by 46% (p < 0.01) and the anti-inflammatory cytokine, IL-10, by 31% (p > 0.05) compared to endotoxaemia. In the spleen, ,-DG treatment decreased the ratio of IL-1, to IL-10 by 55% (p < 0.05), demonstrating an anti-inflammatory trend. These data suggest that ,-DG differentially modulates cytokine response in the lung and spleen and modifies the pro- and anti-inflammatory balance during an early period of endotoxaemia in juvenile rats. [source] Effects of local delivery of trapidil on neointima formation in a rabbit angioplasty modelBRITISH JOURNAL OF PHARMACOLOGY, Issue 3 2000Kai Zacharowski Smooth muscle cell (SMC) proliferation can result in luminal reduction of a vessel following balloon angioplasty. This study was designed (i) to determine if local administration of trapidil (triazolopyrimidine) into a vessel wall reduces neointima formation, and (ii) to explore the mechanism involved in the subsequent reduction in cell proliferation. Following balloon angioplasty in 40 anaesthetized New Zealand White rabbits, trapidil (50,200 mg) or its vehicle (saline) was injected into the dilated vessel wall of the right femoral artery. Experimental groups and time of investigation: (I) vehicle (2 weeks, n=3), (II) trapidil-100 mg (2 weeks, n=3), (III) vehicle (3 weeks, n=8), (IV) trapidil-50 mg (3 weeks, n=5); (V) trapidil-100 mg (3 weeks, n=9) or (V) trapidil-200 mg (3 weeks, n=7). After 2 weeks, there was a significant reduction of intimal hyperplasia (expressed as intima to media area ratio) in the trapidil group compared with vehicle (0.44±0.04 vs 0.93±0.04, *P<0.05) and also a significant reduction in cell proliferation (% ratio of BrdU-positive cells to total cell number: vehicle 14±2% vs trapidil 6±1%, *P<0.05). After 3 weeks, there was a dose-dependent reduction of intimal hyperplasia in the trapidil groups compared with vehicle (trapidil 50 mg 1.14±0.04; trapidil 100 mg 0.91±0.09*; trapidil 200 mg 0.77±0.09* vs vehicle 1.67±0.23, *P<0.05). Thus, the local administration of trapidil to the rabbit femoral artery reduces the neointima formation, which occurs 2 or 3 weeks after balloon angioplasty via a mechanism, which is dependent on inhibition of cell proliferation. British Journal of Pharmacology (2000) 129, 566,572; doi:10.1038/sj.bjp.0703098 [source] Glutathione deficiency intensifies ischaemia-reperfusion induced cardiac dysfunction and oxidative stressACTA PHYSIOLOGICA, Issue 1 2001S. Leichtweis The efficacy of glutathione (GSH) in protecting ischaemia-reperfusion (I-R) induced cardiac dysfunction and myocardial oxidative stress was studied in open-chest, stunned rat heart model. Female Sprague,Dawley rats were randomly divided into three experimental groups: (1) GSH-depletion, by injection of buthionine sulphoxamine (BSO, 4 mmol kg,1, i.p.) 24 h prior to I-R, (2) BSO injection (4 mmol kg,1, i.p.) in conjunction with acivicin (AT125, 0.05 mmol kg,1, i.v.) infusion 1 h prior to I-R, and (3) control (C), receiving saline treatment. Each group was further divided into I-R, with surgical occlusion of the main left coronary artery (LCA) for 30 min followed by 20 min reperfusion, and sham. Myocardial GSH content and GSH : glutathione disulphide (GSSG) ratio were decreased by ,50% (P < 0.01) in both BSO and BSO + AT125 vs. C. Ischaemia-reperfusion suppressed GSH in both left and right ventricles of C (P < 0.01) and left ventricles of BSO and BSO + AT125 (P < 0.05). Contractility (+dP/dt and ,dP/dt) in C heart decreased 55% (P < 0.01) after I and recovered 90% after I-R, whereas ±dP/dt in BSO decreased 57% (P < 0.01) with ischaemia and recovered 76 and 84% (P < 0.05), respectively, after I-R. For BSO + AT125, ±dP/dt were 64 and 76% (P < 0.01) lower after ischaemia, and recovered only 67 and 61% (P < 0.01) after I-R. Left ventricular systolic pressure in C, BSO and BSO + AT125 reached 95 (P > 0.05) 87 and 82% (P < 0.05) of their respective sham values after I-R. Rate-pressure double product was 11% (P > 0.05) and 25% (P < 0.05) lower in BSO and BSO + AT125, compared with Saline, respectively. BSO and BSO + AT125 rats demonstrated significantly lower liver GSH and heart Mn superoxide dismutase activity than C rats after I-R. These data indicate that GSH depletion by inhibition of its synthesis and transport can exacerbate cardiac dysfunction inflicted by in vivo I-R. Part of the aetiology may involve impaired myocardial antioxidant defenses and whole-body GSH homeostasis. [source] Viability of fibroblasts in a novel probiotic storage mediaDENTAL TRAUMATOLOGY, Issue 5 2010E Çaglar The aim of the present in vitro study was to evaluate the number of viable PDL cells of avulsed teeth treated by Hank's Balanced Salt Solutions (HBSS), saline, a novel probiotic solution and milk. Thirty-six freshly extracted single-rooted human teeth with closed apices were divided into one of the four experimental groups and two control groups (N = 6 each). The positive and negative controls corresponded to 0 min and an 8-h dry time respectively. Following extraction, the coronal 3 mm of PDL tissue was scraped with a #15 scalpel to remove cells that might have been damaged. The experimental teeth were dried for 30 min followed by a 45 min immersion in one of the four experimental media. Each experimental tooth, after drying and soaking, was incubated for 30 min with a 2.5 ml solution of 0.2 mg ml,1 of collagenase CLS II and a 2.4 mg ml,1 solution of dispase grade II in phosphate buffer saline (PBS). The cells were then labelled with 0.4% Trypan blue for determination of viability. The teeth stored in positive control demonstrated the highest number of viable PDL cells followed in rank order by HBSS, saline, Lactobacillus reuteri solution and milk. There was no significant difference in the number of viable PDL cells between HBSS, milk, L. reuteri solution and saline. Within the parameters of this study, it appears that probiotic may be able to maintain PDL cell viability as HBSS, milk, or saline. [source] Evaluation of fracture resistance in simulated immature teeth using resilon and ribbond as root reinforcements , An in vitro studyDENTAL TRAUMATOLOGY, Issue 4 2009Hiremath Hemalatha Material and Methods:, Sixty five freshly extracted human maxillary anterior teeth were prepared with a Peeso no. 6 to simulate immature teeth (Cvek's stage 3 root development). After instrumentation, each root was irrigated with sodium hypochlorite and with ethylene diamino tetra acetic acid to remove the smear layer. To simulate single visit apexification technique a 4,5 mm white Pro Root mineral trioxide aggregate plug was placed apically using schilder carrier. The teeth were divided into three experimental groups and one control group. Group I , control group (root canals instrumented but not filled); Group II , backfilled with thermoplastisized gutta-percha using AH plus sealer; Group III , reinforced with Resilon using epiphany sealer; Group IV , reinforced with Ribbond fibers using Panavia F luting cement. A Universal Testing Machine was used to apply a load, at the level of the lingual cementoenamel junction with a chisel-shaped tip The peak load to fracture was recorded and statistical analysis was completed using student's t -test. Results:, Values of peak load to fracture were 1320.8, 1604.88, 1620, and 1851newtons for Group I to Group IV respectively. The results of student's t -test, revealed no significant difference (P > 0.05,) between Group II and Group III. Comparison between Group IV and Group III and between Group IV and Group II revealed highly significant difference (P > 0.001). Conclusions:, Teeth reinforced with Ribbond fibers using Panavia F luting cement showed the highest resistance to fracture. Resilon could not strengthen the roots and showed no statistically significant difference when compared with thermopasticised gutta-percha in reinforcing immature tooth when tested with universal testing machine in an experimental model of immature tooth. [source] Effect of root surface treatment with propolis and fluoride in delayed tooth replantation in ratsDENTAL TRAUMATOLOGY, Issue 6 2008Jéssica Lemos Gulinelli Nevertheless, an extended extraoral period damages the periodontal ligament and results in external root resorption. The purpose of this study was to assess by histologic and histometric analysis, the influence of propolis 15% (natural resinous substance collected by Apis mellifera bees from various plants) and the fluoride solution used as root surface treatment on the healing process after delayed tooth replantation. Thirty Wistar (Rattus norvegicus albinus) rats were submitted to extraction of their upper right incisor. The teeth were maintained in a dry environment for 60 min. After this, the pulp was extirpated and the papilla, enamel organ and periodontal ligament were removed with scalpel. The teeth were divided into three experimental groups: Group I , teeth immersed in 20 ml of physiologic saline; Group II , teeth immersed in 20 ml of 2% acidulated phosphate sodium fluoride; Group III , teeth immersed in 20 ml of 15% propolis. After 10 min of immersion in the solutions, the root canals were dried and filled with calcium hydroxide paste and the teeth were replanted. The animals were euthanized 60 days after replantation. The results showed that similar external root resorption was seen in the propolis and fluoride groups. Teeth treated with physiologic saline tended to have more inflammatory root resorption compared with those treated with fluoride or propolis. However, the comparative analysis did not reveal statistically significant differences (P > 0.05) between the treatment modalities when used for delayed tooth replantation. [source] Sealing evaluation of the cervical base in intracoronal bleachingDENTAL TRAUMATOLOGY, Issue 6 2003Luciane Dias De Oliveira Abstract,,, Discoloration of non-vital teeth is an esthetic deficiency frequently requiring bleaching treatment. The purpose of this study was to evaluate in vitro the cervical base efficacy in order to prevent or to minimize the leakage along the root canal filling and into the dentinal tubules. Thirty-eight extracted single-root human teeth were used, which were biomechanically prepared, filled, and divided into three experimental groups: G1, a cervical base was applied (3 mm of thickness) below the cemento-enamel junction, with resin-modified glass-ionomer cement (Vitremer); G2, the base was done with glass-ionomer cement (Vidrion R); and G3 (Control), did not receive any material as base. A mixture of sodium perborate and hydrogen peroxide 30% was placed inside the pulp chamber for 3 days, and the access opening was sealed with Cimpat. This procedure was repeated thrice. Soon after this, a paste of calcium hydroxide was inserted into the pulp chamber for 14 days. All teeth were covered with two layers of sticky wax, except the access opening, and immersed in blue India Ink for 5 days. The results did not show statistically significant differences between the three groups concerning the leakage inside the dentinal tubules. Regarding the apical direction, a statistical difference (anovaP < 0.05) was observed among the experimental group G1 and control group G3. No statistically significant difference was observed between G2 and G3 groups. Therefore, the placement of a cervical base before internal bleaching procedures is still recommended. [source] Immediate early gene (ZENK, Arc) expression in the auditory forebrain of female canaries varies in response to male song qualityDEVELOPMENTAL NEUROBIOLOGY, Issue 3 2005Stefan Leitner Abstract In male songbirds, the song control pathway in the forebrain is responsible for song production and learning, and in females it is associated with the perception and discrimination of male song. However, experiments using the expression of immediate early genes (IEGs) reveal the activation of brain regions outside the song control system, in particular the caudomedial nidopallium (NCM) and the caudomedial mesopallium (CMM). In this study on female canaries, we investigate the role of these two regions in relation to playback of male songs of different quality. Male canaries produce elaborate songs and some contain syllables with a more complex structure (sexy syllables) that induce females to perform copulation solicitation displays (CSD) as an invitation to mate. Females were first exposed to playback of a range of songs of different quality, before they were finally tested with playback of songs containing either sexy or nonsexy syllables. We then sectioned the brains and used in situ hybridization to reveal brain regions that express the IEGs ZENK or Arc. In CMM, expression of ZENK mRNA was significantly higher in females that last heard sexy syllables compared to those that last heard nonsexy syllables, but this was not the case for NCM. Expression of Arc mRNA revealed no differences in either CMM or NCM in both experimental groups. These results provide evidence that in female canaries CMM is involved in female perception and discrimination of male song quality through a mechanism of memory reconsolidation. The results also have further implications for the evolution of complex songs by sexual selection and female choice. © 2005 Wiley Periodicals, Inc. J Neurobiol, 2005 [source] Intersensory redundancy educates selective attention in bobwhite quail embryosDEVELOPMENTAL SCIENCE, Issue 6 2006Robert Lickliter We assessed whether exposure to amodal properties in bimodal stimulation (e.g. rhythm, rate, duration) could educate attention to amodal properties in subsequent unimodal stimulation during prenatal development. Bobwhite quail embryos were exposed to an individual bobwhite maternal call under several experimental and control conditions during the day prior to hatching. Experimental groups received redundant auditory and visual exposure to the temporal features of an individual maternal call followed by unimodal auditory exposure to the same call immediately or after a 2-hr or 4-hr delay. Control groups received (1) the same exposure but in the reverse sequence (unimodal , redundant bimodal), (2) asynchronous bimodal , unimodal, (3) only unimodal exposure, or (4) only bimodal exposure. All experimental groups showed a significant preference for the familiar maternal call over a novel maternal call when tested 2 days after hatching, whereas none of the control groups showed a significant preference for the familiar call. These results indicate that intersensory redundancy can direct attention to amodal properties in bimodal stimulation and educate attention to the same amodal properties in subsequent unimodal stimulation where no intersensory redundancy is available. [source] Age-dependent reproductive costs and the role of breeding skills in the Collared flycatcherACTA ZOOLOGICA, Issue 2 2007Joanna Sendecka Abstract This study addressed whether there are any age-related differences in reproductive costs. Of especial interest was whether young individuals increased their reproductive effort, and thereby their reproductive cost, as much as older birds when brood size was enlarged. To address these questions, a brood-size manipulation experiment with reciprocal cross-fostering of nestlings of young and middle-aged female Collared flycatchers, Ficedula albicollis, was performed on the Swedish island of Gotland. Nestlings' body mass, tarsus length and survival were recorded to estimate the parental ability and parental effort of the experimental female birds. Female survival and clutch size were recorded in the following years to estimate reproductive costs. We found that middle-aged female flycatchers coped better with enlarged broods than younger females or invested more in reproduction. In the following year, young female birds that had raised enlarged broods laid smaller clutches than the females from all the other experimental groups. This result shows that the young female birds pay higher reproductive costs than the middle-aged females. Both young and middle-aged female flycatchers seemed to increase their reproductive effort when brood size was increased. However, such an increase resulted in higher reproductive costs for the young females. The difference in reproductive costs between birds of different ages is most likely a result of insufficient breeding skills of the young individuals. [source] Effects of aphids on foliar foraging by Argentine ants and the resulting effects on other arthropodsECOLOGICAL ENTOMOLOGY, Issue 1 2008CRYSTAL D. GROVER Abstract 1.,Although interactions between ants and honeydew-producing insects have received considerable study, relatively little is known about how these interactions alter the behaviour of ants in ways that affect other arthropods. In this study, field and greenhouse experiments were performed that examined how the presence of aphids (Aphis fabae solanella) on Solanum nigrum influenced the foraging behaviour of Argentine ants (Linepithema humile) and, in turn, modified the extent to which ants deter larval lacewings (Chrysoperla rufilabris), which are known aphid predators. 2.,A field experiment demonstrated that the level of foliar foraging by ants increased linearly with aphid abundance, whereas no relationship existed between the level of ground foraging by ants and aphid abundance. 3.,In the greenhouse, as in the field, foliar foraging by ants greatly increased when aphids were present. Higher levels of foliar foraging led to a twofold increase in the likelihood that ants contacted aphid predators. As a result of these increased encounters with ants, lacewing larvae were twice as likely to be removed from plants with aphids compared with plants without aphids. Once contact was made, however, the behaviour of ants towards lacewing larvae appeared similar between the two experimental groups. 4.,Argentine ants drive away or prey upon a diversity of arthropod predators and parasitoids, but they also exhibit aggression towards certain herbivores. Future work should attempt to quantify how the ecological effects that result from interactions between honeydew-producing insects and invasive ants, such as L. humile, differ from those that result from interactions between honeydew-producing insects and native ants. [source] Stylet penetration behavior resulting in inoculation of a semipersistently transmitted closterovirus by the whitefly Bemisia argentifoliiENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2002D.D. Johnson Abstract The electrical penetration graph (EPG) technique was used to determine what part of stylet penetration behavior by the whitefly vector, Bemisia argentifolii Bellows & Perring (Homoptera: Aleyrodidae), is lettuce chlorosis virus (LCV) inoculated in the host plant Malva parviflora L. LCV is a semipersistently-transmitted closterovirus. Since closteroviruses generally are found in the phloem of their plant hosts, this study tested the hypothesis that virus inoculation occurs during the phloem phase of stylet penetration behavior. Virus-exposed whiteflies were allowed to feed on uninfected host plants, and the whiteflies were divided into two experimental groups: group 1 attained phloem phase on the uninfected plants, and group 2 did not attain phloem phase. Two series of tests were conducted, one where whiteflies were manipulated so that the amount of time spent in non-phloem phase stylet penetration behaviors was similar between group 1 and group 2, and a second series of tests where whiteflies were manipulated so that the number of intracellular punctures made during stylet penetration was similar between group 1 and group 2. Both series of tests indicated that virus inoculation took place primarily during phloem phase. Considering only individual whiteflies shown to be capable of transmitting virus, 11 of 23 whiteflies (48%) in the phloem phase treatment successfully inoculated the virus whereas only one of 19 whiteflies (5%) in the non-phloem phase treatment successfully inoculated the virus (P= 0.00008). [source] Dose-dependent growth inhibition and bioaccumulation of hexavalent chromium in land snail Helix aspersa aspersaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2000Michaël C, urdassier Abstract The toxicity of Cr6+ was determined in a laboratory environment in the snail Helix aspersa aspersa. The effects on growth were evaluated on animals reared in controlled conditions at the age of one month that had been exposed for 28 d to increasing doses of Cr6+ mixed in with their food. Two experimental groups were set up with concentrations of chromium in the feed of 250 to 1,250 ,g/g (test 1) and 100 to 800 ,g/g (test 2). Growth inhibition was dose dependent, and the mean EC50 calculated at four weeks for tests 1 and 2 were, respectively, 354.7 and 298.8 ,g/g and for the EC10 195.3 and 160.9 ,g/g. The levels of Cr6+ bioaccumulated in the foot and the viscera of the snails were dose dependent in both types of tissues. The highest concentrations occurred in the viscera, the levels being 0.79 ,g/g in the controls and reaching 3,067 ,g/g in the animals exposed to the maximum contamination (1,250 ,g/g). These high levels of bioaccumulation in addition to the lower concentrations of Cr6+ excreted in the feces than those present in the food suggest that chromium is not physiologically regulated by Helix aspersa. The results provide added support for the use of snails as a model to determine the toxicity of substances in laboratory biotests by measuring the effects on growth and by assessing bioaccumulation. [source] Effects of chronic treatment with valproate and oxcarbazepine on ovarian folliculogenesis in ratsEPILEPSIA, Issue 7 2008Ali Cansu Summary Purpose: We aimed to define the morphologic effects of valproate (VPA) and oxcarbazepine (OXC) on ovarian folliculogenesis in rats. Methods: Forty female wistar rats (21,24 days old and weighted between 46.4 and 55.3 g) were divided equally into 4 experimental groups, which were applied tap water (control group), 300 mg/kg/day VPA, 100 mg/kg/day OXC, and both VPA and OXC via gavage for 90 days. Ovaries of the rats on proestrous and diesterous phase of estrous cycle according to daily vaginal smear were taken out and placed in a fixation solution. Immunohistochemical and apoptosis (TUNEL) staining protocols were applied. Results: The number of follicles decreased and that of corpora lutea increased significantly in OXC, VPA, and OXC+VPA treated groups compared with control group (p < 0.05). The number of TUNEL positive ovarian follicles was 1.40 ± 0.52 in control group, but it significantly increased to 3.50 ± 0.53, 3.50 ± 0.53, and 4.90 ± 0.88 in VPA, OXC, and VPA+OXC groups (p < 0.0001). The increase in the number of TUNEL positive granulosa cells was also significant for OXC and VPA+OXC groups (p < 0.0001). Immunohistochemical HSCORE decreased for TGF,1 and IGF1 staining and increased for P53 staining in all drug groups compared with control group (p < 0.001). Intensity of P53 labeling increased, while intensity of TGF,1, IGF-1, and GDF-9 immunoreactivity decreased significantly in all drug groups compared with control group (p < 0.001). Conclusion: Long-term treatment with VPA or OXC from prepuberty to adulthood causes apoptosis and deterioration of folliculogenesis in rat ovarian follicles. [source] Efficacy screening trials of paroxetine, pentoxifylline, riluzole, pramipexole and venlafaxine in cocaine dependenceADDICTION, Issue 2005Domenic A. Ciraulo ABSTRACT Aims The two studies presented here were conducted to assess the efficacy of paroxetine, pentoxifylline, riluzole, venlafaxine and pramipexole as medications for the treatment of cocaine dependence. Design A multi-arm, modified blinded, placebo-controlled design was used. Setting The studies were conducted at the Boston VA Healthcare System and the Boston University School of Medicine Medication Development Research Unit (MDRU). Participants Participants met criteria for cocaine dependence during a 2-week screening period. Intervention Following random assignment to one of the treatment groups, subjects received active medication or placebo for 8 weeks in combination with cognitive behavioral counseling. In the first study the efficacy of the antidepressant paroxetine (20 mg daily), the phosphodiesterase inhibitor pentoxifylline (1200 mg daily) and the glutamate release inhibitor riluzole (100 mg daily) was assessed. The antidepressant venlafaxine (150 mg daily) and the dopamine agonist pramipexole (1.5 mg daily) were evaluated in the second study. Measurements Urine benzoylecgonine (BE) concentrations, self-report of cocaine use and global impression scores served as primary outcome measures. Secondary measures included assessments of cocaine craving and psychiatric functioning. Adverse events were monitored during the treatment period. Findings None of the active medications produced greater reductions in urine BE concentrations over the treatment period than did placebo. There were trends for BE levels to become reduced in the pentoxifylline group during the first 4 weeks of treatment and for Addiction Severity Index (ASI) drug composite scores to be lower in the pentoxyfylline group at end-point compared to the placebo group. Significant within-group reductions in reported cocaine use and craving were found for all treatment groups, but none of the active medications were superior to placebo on these measures. The accuracy of self-reported cocaine use declined over the study period. Overall, the active medications were well tolerated. Conclusions This study does not support the use of paroxetine, pentoxifylline, riluzole, venlafaxine or pramipexole for the treatment of cocaine dependence. However, these results need to be interpreted with caution because of the small size and lack of homogeneity of the experimental groups. [source] Multiple Paternity and Similar Variance in Reproductive Success of Male and Female Wood Mice (Apodemus sylvaticus) Housed in an EnclosureETHOLOGY, Issue 10 2001Susan Bartmann The mating system and variance in individual reproductive success in wood mice (Apodemus sylvaticus) were analysed genetically and using observational studies within a large cage system in an outdoor enclosure. Four experimental groups contained four males and four females, each individually marked with a transponder (small computer chips injected under the skin) allowing individual detection of animals underground or within nest boxes without disturbance. The probability of paternity was analysed by comparing frequencies of cohabitation of males and females. In addition, DNA microsatellite analysis revealed reproductive success of each individual. Multiple paternity was found in 85% of all litters, which were sired by up to all four males. Males with a greater body mass, possibly indicative of a higher rank, sired more offspring than those with lower body mass. Interestingly, variance in the reproductive success of males and females did not differ. There was no indication that paternity could be assessed by the time males resided with a female shortly before she became pregnant. Our results indicate wood mice probably have a promiscuous mating system. [source] Dominance Interactions Regulate Worker Mating in the Polygynous Ponerine Ant Gnamptogenys menadensisETHOLOGY, Issue 6 2001Bruno Gobin In queenless ants, workers compete aggressively to be reproductives instead of sterile helpers. To limit the number of reproductives, either mating or egg-laying by mated workers can be regulated. In Gnamptogenys menadensis, all mated workers reproduce, and field data presented here indicate that mating is not random. We removed gamergates experimentally (n=16 groups) to induce mating and gamergate replacement. Virgin workers engaged in agonistic interactions, allowing us to classify them into two groups: dominants performed antennal boxing and biting, while subordinates did not. However, a few subordinates cooperated to immobilize individual dominant workers. This effectively reduced the number of dominants because immobilized dominants became subordinates. Six to 12 wks after the removal of reproductives, between one and eight dominants per colony started to perform ,sexual calling' outside the nest entrance. Sixteen (out of 33) dominants mated with foreign males introduced in five experimental groups. None of the subordinate workers mated. The probability of mating is thus regulated by dominance interactions among workers and immobilizations initiated by infertile workers in this polygynous queenless ant. [source] Effect of augmented visual feedback from a virtual reality simulation system on manual dexterity trainingEUROPEAN JOURNAL OF DENTAL EDUCATION, Issue 1 2005E. Wierinck Little research has been published about the impact of simulation technology on the learning process of novel motor skills. Especially the role of augmented feedback (FB) on the quality of performance and the transfer of the acquired behaviour to a no-augmented FB condition require further investigation. Therefore, novice dental students were randomly assigned to one of three groups and given the task of drilling a geometrical class 1 cavity. The FB group trained under augmented visual FB conditions, provided by the virtual reality (VR) system (DentSimTM). The no-FB group practised under normal vision conditions, in the absence of augmented FB. A control group performed the test sessions without participating in any training programme. All preparations were evaluated by the VR grading system according to four traditional (outline shape, floor depth, floor smoothness and wall inclination), and two critical, criteria (pulp exposure and damage to adjacent teeth). Performance analyses revealed an overall trend towards significant improvement with training for the experimental groups. The FB group obtained the highest scores. It scored better for floor depth (P < 0.001), whilst the no-FB group was best for floor smoothness (P < 0.005). However, at the retention tests, the FB group demonstrated inferior performance in comparison with the no-FB group. The transfer test on a traditional unit revealed no significant differences between the training groups. Consequently, drilling experience on a VR system under the condition of frequently provided FB and lack of any tutorial input was considered to be not beneficial to learning. The present data are discussed in view of the guidance hypothesis of FB, which refers to the apprentice's dependence on FB. [source] Ten-years degradation of resin,dentin bondsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 4 2010Masanori Hashimoto Hashimoto M, Fujita S, Nagano F, Ohno H, Endo K. Ten-years degradation of resin,dentin bonds. Eur J Oral Sci 2010; 118: 404,410. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci The purpose of this study was to evaluate the durability of resin,dentin bonds in 10-yr water-storage testing. Resin,dentin bonded bulk specimens were prepared using six commercially available resin adhesives. The resin,dentin bonded specimens were stored in water for 24 h (control group) or for 10 yr (experimental groups). After each storage period, the specimens were sectioned to make specimen beams and then subjected to a microtensile bond test. After the bond test, fractured surfaces were examined by scanning electron microscopy (SEM). In addition, interfacial observation of silver nanoleakage was performed using the backscatter electron mode of SEM. The bond strengths of four of the six adhesive systems tested decreased significantly after 10 yr. However, no significant bond-strength reduction was recorded for the other two systems. The interfacial observations showed water tree propagation in the bonding resin layer as a typical morphological change after aging for five of the six adhesives tested. Water tree propagation may be a symptom of degradation in the resin bonding layer of resin,dentin bonds. [source] Effect of post-space treatment on retention of fiber posts in different root regions using two self-etching systemsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2008Ling Zhang The effect of post-space treatment on the retention of fiber posts in different root regions was evaluated using two self-etching systems. Post spaces were prepared in extracted premolars and then the root canals were subjected to one of the following post-space treatments: (i) water irrigation (control); (ii) etching with 35% phosphoric acid for 30 s; (iii) irrigation with 17% EDTA followed by 5.25% sodium hypochlorite (NaOCl); and (iv) ultrasonic agitation associated with 17% EDTA and 5.25% NaOCl irrigating solutions. The dentin surfaces were examined under scanning electron microscopy (SEM) after different post-space treatments. Fiber posts were then luted in the treated roots using resin cement with either Clearfil SE Bond or Clearfil DC Bond, and the thin-slice push-out test was performed. Scanning electron microscopy showed that all the post-space treatments tested were effective in removal of the smear layer of debris, or sealer/gutta-percha remnants, on the root canal. The apical push-out strength was affected by post-space treatment. Both 35% phosphoric acid etching and ultrasonic agitation in combination with EDTA/NaOCl irrigation improved the apical push-out strength of the fiber post, regardless of the type of self-etching system. A solo irrigation with an EDTA/NaOCl solution resulted in a lower apical push-out strength compared with the other two experimental groups. [source] Four-year water degradation of a resin-modified glass-ionomer adhesive bonded to dentinEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2004Jan De Munck Glass-ionomers are auto-adhesive to tooth tissue through combined micro-mechanical and chemical bonding. How much each of the two bonding components contributes to the actual bonding effectiveness is, however, not known and there is not much information available on long-term stability. The objective of this study was to assess the bonding effectiveness of a resin-modified glass-ionomer adhesive to dentin after 4 yr of water storage. Fuji Bond LC (GC) was applied without (i) and with pretreatment using (ii) a polyalkenoic acid conditioner and (iii) a 37.5% phosphoric acid etchant. The etchant was used to exclude any chemical interaction with hydroxyapatite. The micro-tensile bond strength (µTBS) to dentin decreased significantly over the 4 yr period in all three experimental groups. After 24 h and 4 yr, the lowest µTBS was recorded when dentin was not pretreated. The highest µTBS was obtained following polyalkenoic acid pretreatment, although this was not significantly different from specimens that were pretreated using phosphoric acid. Pretreating dentin with phosphoric acid intensified micromechanical interlocking at the expense of chemical bonding potential to hydroxyapatite. Nevertheless, correlating the µTBS data with failure analysis through scanning electron microscopy and transmission electron microscopy indicated that combined micro-mechanical and chemical bonding involving pretreatment with the polyalkenoic acid conditioner yielded the most durable bond. [source] Modified Class II open sandwich restorations: evaluation of interfacial adaptation and influence of different restorative techniquesEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2002Ingrid E. Andersson-Wenckert The sandwich technique with resin-modified glass ionomer cement (RMGIC) has been proposed to relieve the contraction stresses of direct resin composite (RC) restorations. The aim of this study was to evaluate the interfacial adaptation to enamel and dentin of modified Class II open RMGIC/RC sandwich restorations and the influence of different light curing techniques and matrix bands. Forty box-shaped Class II fillings were placed in vivo in premolars scheduled for extraction after one month. In groups I and II, a metal matrix was used; RC was inserted with horizontal (group I) and diagonal (group II) increments and cured with indirect/direct light. Group III was performed as group II, but a transparent matrix was used. Group IV was as group II, but with a separating liner between RMGIC and RC. Group V was a closed sandwich restoration. Interfacial quality was studied using SEM replica technique. Gap-free interfacial adaptation to enamel was observed for RMGIC in 70%, for RC in 70% and to dentin for RMGIC in 81%, for RC in 56%. No significant differences were seen between the experimental groups. At the cervical margins, RMGIC showed significantly better adaptation to enamel than RC, 74% and 42%, respectively. In conclusion, the investigated restorations showed a high percentage of gap-free interfacial adaptation in vivo. Interfacial adaptation to dentin and to cervical enamel was significantly better for RMGIC than for RC. [source] Sources of respect: the effects of being liked by ingroups and outgroupsEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 2 2004Naomi Ellemers We investigated the effects of ingroup and outgroup sources of respect, defined as positive social evaluations of self, on group members' emotional reactions and collective self-esteem. We used both natural group memberships (Studies 1 and 2) and laboratory groups (Study 3). We expected that the positive effects of respect derived from an ingroup would not hold when derived from an outgroup source. In Study 1 (N,=,294) respect was manipulated as deriving either from ingroup or outgroup. Although respect produced a positive emotional reaction irrespective of source, collective self-esteem was only enhanced by an ingroup source. In Study 2 (N,=,248), we investigated the concurrent effects of ingroup respect and outgroup respect. As in Study 1, ingroup and outgroup respect both produced positive emotional reactions, but collective self-esteem was only affected by ingroup respect. Additionally, outgroup respect intensified the shame people experienced due to lack of ingroup respect. In Study 3 (N,=,66), participants were immersed in experimental groups and ingroup and outgroup respect were manipulated orthogonally. Interactive effects of the two sources of respect indicated that high outgroup respect could not compensate for low ingroup respect, and if anything had an adverse effect. Copyright © 2004 John Wiley & Sons, Ltd. [source] The effects of N-acetylcysteine on the expression of matrix metalloproteinase-2 and tissue inhibitor of matrix metalloproteinase-2 in hepatic fibrosis in bile duct ligated ratsHEPATOLOGY RESEARCH, Issue 12 2008Arezou Rezaei Aim:, N-acetylcysteine can inhibit the formation of intracellular reactive oxygen intermediates. Cellular redox state plays a role in regulating the secretion of matrix metalloproteinase-2. We investigated the effects of N-acetylcysteine on the expression of matrix metalloproteinase-2 and tissue inhibitor of matrix metalloproteinase-2. Methods:, Bile duct ligated rats were used as a model of hepatic fibrosis. We compared the level of gene expression (using real-time reverse transcription polymerase chain reaction [RT,PCR]), liver function parameters, hepatic reactive oxygen production, lipid peroxidation and glutathione state in experimental groups. Results:, N-acetylcysteine treatment significantly improved liver function parameters including the plasma levels of aspartate aminotransferase, alkaline phosphatase, gamma-glutamyl transpeptidase and bilirubin. In addition, significant improvement of glutathione state and reactive oxygen production were observed. Hepatic lipid peroxidation was reversed by N-acetylcysteine treatment. Although N-acetylcysteine treatment did not completely normalize the increased matrix metalloproteinase-2 expression, it significantly decreased its level by 65%. N-acetylcysteine treatment also significantly decreased matrix metalloproteinase-2 activity and normalized tissue inhibitor of matrix metalloproteinase-2 expression. Conclusion:, Collectively, N-acetylcysteine showed inhibition of matrix metalloproteinase-2 expression and activity. In addition, administration of N-acetylcysteine was associated with downregulation of the expression of tissue inhibitor of matrix metalloproteinase-2 and amelioration of oxidative stress in the liver of bile duct ligated rats. [source] Effect of tooth loss on spatial memory and trkB-mRNA levels in ratsHIPPOCAMPUS, Issue 6 2008Kaoruko Yamazaki Abstract The mechanism by which tooth loss accelerates spatial memory impairment is unknown. The purpose of this study was to test the hypothesis that tooth loss affects trkB-mRNA levels and leads to an accelerated decrease in the hippocampal cell density in rats. A radial maze was used to evaluate the spatial memory of male Wistar rats that were categorized based on the number of extracted molar teeth. Number of hippocampal pyramidal cells and the trkB-mRNA expressions in the amygdala, perirhinal cortex, thalamus, and the hippocampal CA1, CA3, and CA4 areas, were evaluated using molecular biological techniques. Seven weeks after tooth extraction, maze performance was significantly lower in each tooth loss group than in the control group, and the number of extracted teeth was inversely proportional to the induction of the trkB-mRNA and the hippocampal cell density. The average weight of rats increased by controlled feeding throughout the experiment without showing a significant difference between the control and experimental groups. The results indicated that, in rats, the spatial memory-linked trkB-mRNA was reduced in association with the tooth loss; this supports the hypothesis and suggests that teeth have a role in the prevention of spatial memory impairment. © 2008 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||||||||||||||||||||