Host-finding capacity of schistosome cercariae: comparative efficiency of methods of mouse infection and a radioisotope assay system

1977 ◽  
Vol 51 (2) ◽  
pp. 105-113 ◽  
Author(s):  
Niels Ørnbjerg Christensen ◽  
Flemming Frandsen ◽  
Peter Nansen
Keyword(s):  
Exposure Period ◽  
Host Finding ◽  
Assay System ◽  
Total Darkness ◽  
Experimental Conditions ◽  
Comparative Efficiency ◽  
Immersion Technique ◽  
Tail Immersion ◽  
Direct Proportionality ◽  
Tail Bound

ABSTRACTThe efficiency of five different methods of infection of mice with Schistosoma mansoni or S. intercalatum cercariae was compared; of these the ring method, the tail immersion technique, and the paddling method were found to be the most effective.A new radioisotope assay system for cercarial host-finding capacity is described. This employs the tail immersion technique with radiolabelled S. mansoni cercariae. The amount of tail-bound radioactivity retained after exposure to radiolabelled cercariae was used to measure the host-finding capacity of the cercariae under various experimental conditions. A direct proportionality was found to exist between the number of penetrating radiolabelled cercariae and the subsequent tail-bound radioactivity. Also, a direct proportionality was demonstrated between the number of labelled larvae available in the suspension and the subsequent tail-bound radioactivity. The influence of light and of length of exposure period on cercarial host-finding was analysed. After an exposure period of 30 minutes the amount of radioactivity confined to tails in the light greatly exceeded that of tails exposed in total darkness. However, after 60 minutes comparable radioactivity levels were achieved in the tails exposed in the light or in total darkness, respectively. In the light, maximum tail-bound radioactivity was achieved after 20 minutes exposure and no further change was observed in the radioactivity level at 40 and 60 minutes.

A Simple Restraining Chamber for Exposing Mice to Schistosome Cercariae by the Tail Immersion Technique

1982 ◽  
Vol 68 (3) ◽  
pp. 504
Author(s):  
Niels Ornbjerg Christensen ◽  
Flemming Frandsen ◽  
Peter Nansen ◽  
Age Schultz
Keyword(s):  
Immersion Technique ◽  
Tail Immersion

Toxicity of cadmium and zinc to the decaudised cercarial life-span of Diplostomum spathaceum (Trematoda: Diplostomidae)

Parasitology ◽  
2003 ◽  
Vol 127 (5) ◽  
pp. 497-506 ◽  
Author(s):  
N. J. MORLEY ◽  
M. CRANE ◽  
J. W. LEWIS
Keyword(s):  
Life Span ◽  
Prolonged Exposure ◽  
Water Hardness ◽  
Exposure Period ◽  
Fish Host ◽  
Metal Exposure ◽  
Experimental Conditions ◽  
Metal Concentrations ◽  
Specific Level ◽  
Diplostomum Spathaceum

The toxicity of cadmium and zinc at concentrations ranging from 0·1 to 10 000 μg/l to the life-span of decaudised cercarial bodies (cercariae that have shed their tails) of Diplostomum spathaceum was investigated. The effects of metal exposure at 3 temperatures (12, 20, and 25 °C) and 3 levels of water hardness (distilled water, soft water and hard water) were studied. In general, under most experimental conditions increasing metal concentrations reduced the life-span of decaudised cercariae. Increasing water hardness and decreasing water temperature caused an increase in the life-span of both control and metal exposed decaudised cercariae. However, at certain isolated metal concentrations, associated with a specific level of water hardness and temperature, increased survival above controls occurred. Differences in the relative toxicity of cadmium and zinc were dependent on the environmental conditions of exposure. The decaudised cercarial life-span under metal exposure was found to be generally independent of the overall cercarial survival and tail loss in most experimental conditions. Prolonged exposure to cadmium and zinc caused changes in the decaudised cercarial life-span when compared to individuals decaudised during the initial 24 h exposure period to those which were decaudised during the final 24 h period of cercarial survival. The validity of studying the decaudised cercarial life-span as an indicator of ‘fitness’ of larvae to migrate through the tissues of the target fish host, in terms of glycogen utilization, was assessed for those cercariae decaudised during the initial 24 h exposure period only. A limited reduction in the decaudised cercarial life-span during this period compared to controls was recorded, which may possibly indicate a reduced penetration ‘fitness’ of cercariae exposed to cadmium and zinc. The importance and relevance of these findings to parasite migration and establishment in the fish host are discussed.

scholarly journals Current Research Trends on the Effects of Microplastics in Soil Environment Using Earthworms: Mini-Review

2021 ◽  
Vol 43 (4) ◽  
pp. 299-306
Author(s):  
Jaeryung Hur ◽  
Eun Hea Jho
Keyword(s):  
Marine Environment ◽  
Human Life ◽  
Exposure Period ◽  
Soil Environment ◽  
Single Exposure ◽  
Experimental Conditions ◽  
Test Species ◽  
Oxidation Stress ◽  
Induced Changes ◽  
The Impact

Objectives : The increase in the amount of plastics used has brought convenience to human life, but has also caused various environmental problems such as problems related to microplastics. Microplastics are defined as small plastic particles with a size of under 5 mm. As of now, research on microplastics has been largely focusing on the marine environment, and studies on microplastics in soil environment are on the rise in very recent years. Thus, the environmental impact of microplastics on the soil environment are insufficient than those on the marine environment, and there is a need for more studies. Therefore, this mini-review attempts to examine the studies on microplastics in soil environment focusing on the studies using earthworms as a test species.Methods : Published studies on microplastics in soil environment were identified by searching Web of Science. The focus of this mini-review was to gather the published articles reporting the effect of microplastics on earthworms in the absence and presence of other chemical contaminants.Results and Discussions : The number of studies evaluating the effect of microplastics in soil are significantly increasing, and earthworms are being mostly used as the test species. Experimental conditions were divided into two types: Single exposure to microplastics and combined exposure to microplastics and other chemicals. In most studies, changes in the biomarkers which are related to oxidation stress of earthworms were confirmed, and direct damage to intestinal tissues of earthworms was also observed. However, in the case of the changes of the biomarkers of earthworms, their patterns were different depending on the experimental conditions (i.e., concentrations of microplastics and chemicals, microplastics size and type, exposure period, etc.). Also, the avoidance behavior of earthworms and the internal accumulation of microplastics and co-existing chemicals were not consistent among the studies. Thus, the effects of microplastics on earthworms are not clear yet, although they seem to have some adverse effects.Conclusions : This study showed that the interest in the impact of microplastics in the soil environment has been increased recently, and earthworms are being used mostly in the studies. Yet, there is no standardized method to study the effect of microplastics on earthworms. Studies so far confirmed that microplastics induced changes in and outside of earthworm bodies. However, due to various experimental conditions, it seemed that consistent results could not be confirmed in those researches. For that reason, this study suggests that standardized research methods for microplastics researches using earthworms as a test species need to be established and need to be applied to further studies.

Neutrophils play a critical role in development of LPS-induced airway disease

2002 ◽  
Vol 283 (5) ◽  
pp. L952-L962 ◽  
Author(s):  
Jordan D. Savov ◽  
Stephen H. Gavett ◽  
David M. Brass ◽  
Daniel L. Costa ◽  
David A. Schwartz
Keyword(s):  
Transforming Growth Factor ◽  
Critical Role ◽  
Recovery Period ◽  
Exposure Period ◽  
Airway Disease ◽  
Transforming Growth Factor Β1 ◽  
Experimental Conditions ◽  
Control Serum ◽  
Inhalation Challenge

We investigated the role of neutrophils in the development of endotoxin-induced airway disease via systemic neutrophil depletion of C3H/HeBFeJ mice and coincident inhalation challenge with lipopolysaccharide (LPS) over a 4-wk period. Mice were made neutropenic with intraperitoneal injections of neutrophil antiserum before and throughout the exposure period. Experimental conditions included LPS-exposed, antiserum-treated; LPS-exposed, control serum-treated; air-exposed, antiserum-treated; and air-exposed, control serum-treated groups. Physiological, biological, and morphological assessments were performed after a 4-wk exposure and again after a 4-wk recovery period. After the 4-wk exposure, LPS-induced inflammation of the lower airways was significantly attenuated in the neutropenic mice, although airway responsiveness (AR) to methacholine (MCh) remained unchanged. After the recovery period, LPS-exposed neutrophil-replete mice had increased AR to MCh when compared with the LPS-exposed neutropenic animals. Morphometric data indicate that the 4-wk exposure to LPS leads to a substantial expansion of the subepithelial area of the medium-sized airways (90–129 μm diameter) in nonneutropenic mice but not neutropenic mice, and this difference persisted even after the recovery period. Expression of bronchial epithelial and subepithelial transforming growth factor-β1 (TGF-β1) was diminished in the challenged neutropenic mice compared with the neutrophil-sufficient mice. These studies demonstrate that neutrophils play a critical role in the development of chronic LPS-induced airway disease.

Age and Glare Recovery Time for Low-Contrast Stimuli

1994 ◽  
Vol 38 (9) ◽  
pp. 496-499 ◽  
Author(s):  
Frank Schieber
Keyword(s):  
Older Adults ◽  
Recovery Time ◽  
Age Groups ◽  
Exposure Period ◽  
Experimental Conditions ◽  
Low Contrast ◽  
Experimental Estimate ◽  
Older Subjects ◽  
Dynamic Components ◽  
Time Required

The purpose of this study was to obtain a rigorous experimental estimate of the time required to recover from the deleterious effects of glare. Low contrast test stimuli were employed to increase the potential sensitivity of the procedure. Multiple age groups were sampled since susceptibility to glare effects is known to increase with advancing years. Glare recovery time assessments were collected from 12 young, 12 middle-aged and 16 older adults. Subjects were presented with 10 sec exposures to an intense glare source under highly controlled experimental conditions. Upon the offset of the glare exposure period, the time required to regain sensitivity for low contrast test stimuli was measured. Relative to their younger counterparts, older subjects required 3-times longer to recover from glare exposure. These findings suggest that the dynamic components of glare effects must be considered when designing environments - especially where older observers are involved.

The Nocturnal Ovipositon Behavior of Chrysomya megacephala (Diptera: Calliphoridae) in Brazil and Its Forensic Implications

2020 ◽  
Author(s):  
L T Carneiro ◽  
W T A Azevedo ◽  
V M Aguiar ◽  
M S Couri
Keyword(s):  
Forensic Entomology ◽  
Oviposition Behavior ◽  
Total Darkness ◽  
Artificial Light ◽  
Fume Hood ◽  
Experimental Conditions ◽  
Important Species ◽  
Chrysomya Megacephala ◽  
Average Temperature ◽  
Males And Females

Abstract Chrysomya megacephala (Fab. 1794) (Diptera: Calliphoridae) is a very important species for forensic entomology, mainly contributing estimations of the postmortem interval (PMI) in judicial investigations. There are some doubts about the nocturnal oviposition of these flies, which could lead to errors in the PMI calculation. This study aimed to monitor the nocturnal oviposition behavior of this species through four experimental conditions carried out in laboratory. Ten cages, each containing five males and females (n = 100), were kept in a fume hood and subjected to total darkness or to artificial light for 11 consecutive hours. Two verifications were performed to determine whether the females deposited eggs on the substrate of ~20 g of chicken gizzards per cage. The first verification occurred at 9:00 pm in nocturnal experiments and at 09:00 am in diurnal experiments. The second verification occurred at 05:00 am in nocturnal experiments and at 05:00 pm in diurnal experiments. Each experiment lasted 5 d. Chrysomya megacephala deposited eggs at night under artificial light and in total darkness, but the amount of eggs was significantly lower when compared with the daytime experiments in dark conditions and under natural light. Oviposition occurred when the average temperature was around 25°C (± 2°C) and relative humidity around 73% (± 6%). Night oviposition is a possibility which should not be ruled out. Thus, future experiments are recommended.

Effect of source water quality on solar disinfection rate under multiple experimental conditions

2014 ◽  
Vol 4 (4) ◽  
pp. 714-719
Author(s):  
M. Mansoor Ahammed ◽  
Shilpa Dave
Keyword(s):  
Natural Waters ◽  
Municipal Wastewater ◽  
Heterotrophic Bacteria ◽  
Exposure Period ◽  
Most Probable Number ◽  
Experimental Conditions ◽  
Probable Number ◽  
Solar Disinfection ◽  
Complete Inactivation ◽  
Naturally Occurring

Water samples from four different sources of varying physico-chemical and microbial quality with their naturally occurring microorganisms were exposed to sunlight in polyethylene terephthalate bottles under similar conditions. Up to 3-log10 reduction of total coliforms (TC) was observed during a 6-h exposure period under weak/moderate radiation conditions (<600 W/m2). Complete inactivation of TC was not achieved in 6 h of exposure for waters with larger initial TC such as river water (1 × 103 most probable number [MPN]/100 mL) and treated municipal wastewater (2 × 105 MPN/100 mL) under these conditions. Heterotrophic bacteria showed lower inactivation rates than did TC. The inactivation rate for spiked Escherichia coli was faster than for naturally occurring coliforms. Further tests with compound parabolic collectors showed that complete inactivation of naturally occurring TC could be achieved within 6 h of exposure for all the natural waters tested. The results of the study thus indicate the need to use naturally occurring organisms in testing the effectiveness of solar disinfection, and the importance of source quality on the inactivation rates of microorganisms.

Comparison between 3H-Daunomycin and its Antimitotic and Antimetabolic Activities in Ascites Sarcoma 180

1971 ◽  
Vol 57 (2) ◽  
pp. 67-74 ◽  
Author(s):  
Giovanni Di Fronzo ◽  
Rosella Silvestrini ◽  
Bianca Maria Scarpinato
Keyword(s):  
Nucleic Acids ◽  
Mitotic Activity ◽  
Rna Synthesis ◽  
Acid Synthesis ◽  
Experimental Conditions ◽  
Reduced Dose ◽  
Antimitotic Activity ◽  
Radiochemical Methods ◽  
Direct Proportionality

Daunomycin uptake and its antimitotic and antimetabolic activities have been studied in S 180 ascites cells in vivo. The uptake of the tritiated antibiotic was determined by radiochemical methods 15 min and 2 h after the i. p. administration of scalar doses. The inhibiting effects on nucleic acids biosynthesis was evaluated by determining with autoradiographic and radiochemical methods, the incorporation of 3H-thymidine and 3H-uridine 2 h after daunomycin administration. Parallel studies were carried out on the antimitotic activity. The results obtained indicate that daunomycin is already present in the cells 15 min after injection and in proportion to the dose given. Two hours after the injection the level of incorporated radioactivity is lower. Mitotic activity, measured two h after the treatment, is reduced dose proportionally and is completely absent at doses of 2 mg/kg. The incorporation of 3H-thymidine and 3H-uridine is increased in the cells treated with low doses and is reduced only at doses of 2 mg/kg or higher. In these experimental conditions DNA synthesis is reduced to greater extent than RNA synthesis. A comparison of daunomycin uptake and of nucleic acid synthesis inhibition showed a direct proportionality whereas the effect of daunomycin on mitotic activity and on nucleic acids metabolism appear to be dissociated.

scholarly journals Outcome of prolonged pH exposure on oxidative stress indices and glucose levels in gills and muscles of juvenile koi (Cyprinus carpio)

2019 ◽  
Vol 27 (4) ◽  
pp. 198-207
Author(s):  
Bela Zutshi ◽  
Aradhana Singh ◽  
Proteek Dasgupta
Keyword(s):  
Oxidative Stress ◽  
Gradual Increase ◽  
Reduced Glutathione ◽  
Exposure Period ◽  
Glutathione S Transferase ◽  
Antioxidant Defence ◽  
Experimental Conditions ◽  
Stress Indices ◽  
Glucose Levels ◽  
The Impact

Abstract The impact of a 96-hour exposure period to pH grades on lipid peroxidation (LPO), catalase (CAT), reduced glutathione (GSH), glutathione-S-transferase (GST), and glucose activity in the muscles and gills of koi carp was investigated. Juveniles were exposed to pH grade from 4.0 to 10.0 for four days to observe variance in enzymatic activity. There was a strong correlation between oxidative stress and antioxidant defence activity as an evidential increase was noted in the CAT, GST, and GSH values. Glucose levels were elevated throughout the experimental conditions in both tissues. The fish exhibited a strong behavioral association with a gradual increase in pH grades. There were significant fluctuations in the pH grades with basicity having a greater impact than acidity on the tissues investigated.

Electrolytic Isolation of Twin-Type Shock Deformation Structures

1967 ◽  
Vol 25 ◽  
pp. 318-319
Author(s):  
F. I. Grace ◽  
L. E. Murr
Keyword(s):  
Grain Boundaries ◽  
Thin Foil ◽  
Electrolyte Composition ◽  
Experimental Conditions ◽  
Average Current Density ◽  
Electron Transmission ◽  
Deformation Structures ◽  
The Matrix ◽  
Average Current ◽  
Specimen Edge

During the course of electron transmission investigations of the deformation structures associated with shock-loaded thin foil specimens of 70/30 brass, it was observed that in a number of instances preferential etching occurred along grain boundaries; and that the degree of etching appeared to depend upon the various experimental conditions prevailing during electropolishing. These included the electrolyte composition, the average current density, and the temperature in the vicinity of the specimen. In the specific case of 70/30 brass shock-loaded at pressures in the range 200-400 kilobars, the predominant mode of deformation was observed to be twin-type faults which in several cases exhibited preferential etching similar to that observed along grain boundaries. A novel feature of this particular phenomenon was that in certain cases, especially for twins located in the vicinity of the specimen edge, the etching or preferential electropolishing literally isolated these structures from the matrix.

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