Transmissible disease and population control in some wild animal populations.
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Animals↗
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Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
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Sero-epidemiological study of hepatitis A virus infection among hill-tribe youth and household environmental sanitation, a hill-tribe community in northern Thailand.
A cross-sectional analytic study of 190 hill-tribe youth in a community in the north of Thailand was conducted to investigate the sero-prevalence of HAV and factors related to positive anti-HAV antibody. The studied youth, whose ages ranged from 15 to 24 years, were interviewed about socio-economic status and personal hygiene. Blood specimens were collected to detect anti-HAV by ELISA commercial kit. Household environmental sanitation conditions were observed and drinking water samples were screened for bacterial contamination using SI2 medium. Following the anti-HAV assay, the studied youth were divided into two groups: anti-HAV positive, and anti-HAV negative. The studied variables of the two groups were analyzed by chi2 test to find factors related to anti-HAV positivity. The results revealed that 87% of the studied youth were positive for anti-HAV. There was no statistically significant difference between age group/gender and anti-HAV positivity, p = 0.46 and 0.16, respectively. Approximately 35.79 to 45.79% washed their hands with soap before preparing food, before eating and after using the latrine. About 88% did not improve the potability of their drinking water. The results of screening for bacterial contamination in drinking water samples found that 73.53% were contaminated with coliform bacteria. Factors related to positive anti-HAV antibody included monthly income, number of household members, use of latrine, hand-washing with soap after using latrine, household refuse management and control of insects and rodents; p = 0.04, 0.007, 0.013, 0.008, <0.001 and <0.001, respectively. The findings suggested that appropriate household environmental management should be improved in this community to reduce HAV transmission.
Adolescent↗
Effectiveness of Metarhizium anisopliae (Deuteromycetes) against Ixodes scapularis (Acari: Ixodidae) engorging on Peromnyscus leucopus.
With the incidence of Lyme disease increasing throughout the United States, reducing risk of exposure to the disease is of the utmost concern. In the northeastern U.S., the blacklegged tick, Ixodes scapularis, is the primary vector and the white-footed mouse, (Peromyscus leucopus), the primary reservoir for Borrelia burgdorteri, the bacterium causing Lyme disease. Targeting I. scapularis engorging on white-footed mice with an effective biological control agent, such as the fungus Metarhizium anisopliae, could be an effective and relatively safe control technique. In 2002-2003, we performed laboratory and field experiments to determine whether M anisopliae-treated nesting material could effectively control larval I. scapularis ticks engorging on white-footed mice, and therefore reduce the number of infected nymphal I. scapularis questing the following summer. Our laboratory experiment demonstrated a strong negative effect of M. anisopliae-treated nesting material on survival of I. scapularis larvae feeding on P. leucopus, with 75% versus 35% larval mortality in treatment versus control nests. Our field trials caused only modest, localized reductions in nymphal abundance and had no effect on the proportion of nymphal I. scapularis infected with B. burgdorferi. Field results probably could be improved by increasing the density of nestboxes to allow fungal delivery to a higher proportion of the mouse population and by deploying nestboxes in an area with lower mammalian diversity, such as a suburban landscape.
Animals↗
Investigation of appropriate sanitization frequency for rodent caging accessories: evidence supporting less-frequent cleaning.
The Guide for the Care and Use of Laboratory Animals states that sanitization of caging accessories (for example, filter tops and wire-bar lids) should be done every 2 wk. In this study we tested the hypothesis that organic contamination measured by the presence of ATP associated with organic material (measured with luciferase test swabs) and the number of bacterial colony-forming units (as determined by use of replicate organism detection and counting plates) on caging accessories did not differ significantly at 2 wk versus several months of use. The study evaluated 4 groups: mouse and rat ventilated and static wire-bar cages with or without filter tops (n = 10 per group). The cages were evaluated at several time points from 2 wk to 6 mo. For every cage type, ATP levels did not differ significantly between 14 and 90 d and, in most cases, between 14 and 180 d. In addition the number of bacterial colonies did not differ significantly between 14 and 120 d (and, in some cases, between 14 and 180 d). This study provides data relevant to establishing a validated frequency for sanitization of rodent caging accessories while controlling, and potentially decreasing, costs associated with sanitization.
Animals↗
Angiotensin receptor antagonists in experimental models of chronic renal failure.
The efficacy of angiotensin converting enzyme inhibitors (ACEI) in slowing the advancement of chronic renal disease attests to the importance of angiotensin II (Ang II) in the pathophysiological mechanisms underlying disease progression. It is apparent from studies of the effects of orally-active AT1 receptor antagonists (AT1RA) in experimental models of chronic progressive renal disease, that AT1RA have broadly similar effects to those of ACEI, implying that the favorable effects of ACEI on systemic and renal hemodynamics and indices of glomerular injury are mediated, in large part, by reducing the action of Ang II at AT1 receptors. The possibility remains, however, that differences in the modes of action of ACEI and AT1RA are significant in terms of renal protection and that the two classes of drugs are not therapeutically equivalent. Thus far, however, virtually all experimental studies comparing the renal protective effects of ACEI versus AT1RA have failed to show any convincing differences between the two classes of drug that cannot be attributed to discrepancies in the levels of blood pressure control achieved. As many rodent studies have adopted protocols originally designed to distinguish between the effects of treatment versus no treatment, however, it may be premature to conclude that ACEI and AT1RA are, essentially, therapeutically equivalent. Since both classes of drug have such potent renoprotective effects, the extent of injury that develops in treated rats may be so slight as to compromise the sensitivity of the experimental comparison. Fresh experimental approaches may be required to overcome this issue and resolve any outstanding questions concerning the therapeutic equivalence of AT1RA and ACEI in slowing the progression of renal disease.
Angiotensin II↗
Sterilization of rodent and other pests using a synthetic oestrogen.
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Animals↗
Multivariate determinants of radiocurability. I: Prediction of single fraction tumor control doses.
PURPOSE: The relationship between various laboratory determinants of radiocurability considered alone and in combination, and the observed 50% tumor control dose, has been examined in rodent and xenografted human tumors. METHODS AND MATERIALS: The single fraction 50% tumor control dose (TCD50) under normal and clamp hypoxic conditions, 50% tumor cell transplant dose (Td50), and in vitro estimated tumor cell radiosensitivity parameters, were determined in each of six tumor types (four isografted murine and two xenografted human tumors). Subcutaneous transplant sites and identical or similar tumor generations were used for both the Td50 and TCD50 studies. Radiosensitivity parameters were obtained using the clonogenic assay, after allowing cells to enter the active growth phase to recover from trypsin induced alterations of cell radiosensitivity. Both control and irradiated cells were multiplicity corrected. RESULTS: No single parameter (InTd50, hypoxic fraction, or intrinsic radiosensitivity) correlated with the observed tumor control doses under aerobic or hypoxic conditions. However, when considered in combination, clonogenic fraction (estimated by Td50(-1)), and intrinsic radiosensitivity, predicted the rank-order of tumor control doses with a significant degree of accuracy, and tumor hypoxia influenced the value of the control dose. All parameters were demonstrated to be significant determinants of radiocurability, with substantial tumor to tumor variation in the relative importance of each. For the six tumor types, the combined laboratory determinants predicted 50% tumor control doses which differed from the observed TCD50s by an average of approximately 9 Gy under hypoxic conditions. CONCLUSION: The results obtained demonstrate: (a) the necessity of simultaneously considering all determinants of radiocurability if the role of a single determinant is to be assessed; (b) laboratory determinants may accurately predict tumor radiocurability.
Animals↗
Palatability and toxicity of fipronil as a systemic insecticide in a bromadiolone rodenticide bait for rat and flea control.
Vector control in plague-infested areas requires a simultaneous killing of rodents and their fleas. We investigated the efficacy of a combination of a systemic insecticide, fipronil, in a rodenticide bait formulation under laboratory conditions. Four different concentrations of fipronil (0.05%, 0.005%, 0.0005% with acetone as a solvent, and 0.05% with propylene glycol as a solvent) and two controls (solvents only) were combined with the rodenticide bait (crushed organically grown wheat with 0.005% bromadiolone). Each concentration was offered together with an untreated non-poisonous challenge bait to 10 singly caged Rattus rattus L., each with 100 rat fleas Xenopsylla cheopis Rothschild (Siphonaptera: Pulicidae) in the nest. Treated bait consumption was relatively low and an unsatisfactory rat mortality of around 50% only was obtained in all tests. The palatability of the bait, however, was not affected by the fipronil concentration. Even at the lowest fipronil concentration, average flea mortality was still above 95%, and doses of more than I mg fipronil per kg rat body weight gave a nearly complete kill of fleas. Fipronil can be highly effective as a systemic insecticide to for flea control, provided that a more attractive bait base for roof rats is used.
4-Hydroxycoumarins↗
Neuromechanical control of locomotion in the rat.
Rodent models are being extensively used to investigate the effects of traumatic injury and develop and assess the mechanisms of repair and regeneration. We present quantitative assessment of two-dimensional (2D) kinematics of overground walking and for the first time three-dimensional (3D) joint angle kinematics of all four limbs during treadmill walking in intact adult female Long-Evans rats. Gait cycle with subphases and intralimb and interlimb cyclograms are presented. Phase relationships between joint angles on a cycle-by-cycle basis and interlimb footfalls are assessed using a simple technique. Electromyogram (EMG) data from major flexor and extensor muscles for each of the hindlimb joints and elbow extensor muscles of the forelimbs synchronized to the 3D kinematics are also obtained. Overground walking kinematics, provides information on base of support, stride length, and hindfoot rotation. Treadmill walking kinematics indicate primarily monophasic angle trajectories for the hip and shoulder joints, weak double peak patterns for the knee and elbow joints, and a prominent double peak pattern for the ankle joints. Maximum flexion of the knee during swing precedes that of the ankle, which precedes that of the hip. A mild exercise regimen over 8 weeks does not alter the kinematics. EMG activity indicates specific relationships of the neural activity to joint angle kinematics. We find that the ankle flexors as well as the hip and elbow extensors maintain constant burst duration with changing cycle duration. Data and techniques described here are likely to be useful for quantitative assessment of altered gait and neural control mechanisms after neurotrauma.
Animals↗
[An effective system of measures to protect children's groups from attack by blood-sucking arthropods and the extermination of rodents in the area of children's institutions].
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Animals↗
[Control of harmful mammals].
In the Netherlands, several millions of injurious small mammals are killed yearly. This concerns not only mice and rats but also moles, musk-rats and several other species of rodent. At the request of the Netherlands Society for the Protection of Animals, studies were done on the methods in killing these animals, the effectiveness of these methods and the possibilities of reducing the harm done to the animals. The most important results of these investigations are reported in the present paper.
Animal Welfare↗
The baseline susceptibility levels of Chunya Praomys natalensis, the commonest plague reservoir and crop pest in Tanzania, to warfarin.
P. natalensis were live-trapped at Kibwawa (Chunya district) in November 1977 and November 1979. An F3 generation was raised from animals which tolerated 0.025% a.i. warfarin. All three populations were tested using the WHO standard method (WHO/VBC/75.595), with 0.025% warfarin. The populations tested were fully susceptible to the rodenticide, and the latter was well acceptable to the rodents. In this area, warfarin can be successfully used for controlling P. natalensis. Failure to obtain 100% mortality with the 1977-caught wild population was probably due to vigour tolerance. Regular seminars are recommended to train staff in the rodenticide application.
Animals↗
Pest control industry and vector control activities in Taiwan.
At the end of 1993, there were 117 private pest control companies in Taiwan, with 438 technical managers and 274 technicians. Their business includes the control of mosquitoes, cockroaches, fleas, rodents, termites, houseflies, etc. Pyrethroids and some organophosphates are employed. At present, no applications of insect growth regulators or microbial agents are used by private pest control operators. During dengue epidemics they assist the government in space spraying with insecticides. The Environmental Protection Administration, Executive Yuan, R.O.C., is responsible for the training and management of pest control operators. In addition, the Administration is also in charge of affairs concerning the manufacture, import, registration and sale of environmental pesticides and microbial agents. It establishes protocols for testing the efficacy of insecticides and promotes pest control on the community level.
Aedes↗
Induction of bile acid synthesis by cholesterol and cholestyramine feeding is unimpaired in mice deficient in apolipoprotein AI.
High density lipoprotein (HDL) cholesterol is believed to be preferentially utilized for bile acid synthesis and biliary secretion. In mice, the deletion of apolipoprotein AI (apo AI), the major apolipoprotein in HDL, results in very low plasma HDL-cholesterol levels. This article describes bile acid metabolism in apo AI-deficient (Apo AI(-/-)) mice and their C57BL/6 (Apo AI(+/+)) controls fed either a basal rodent diet alone or containing cholesterol or cholestyramine. Basal plasma HDL-cholesterol levels in the (-/-) mice (<10 mg/dL) were less than 20% of those in their (+/+) controls, but there were no phenotypic differences in either the relative cholesterol content of gallbladder bile, bile acid pool size and composition, fecal bile acid excretion or the activity of, or mRNA level for, cholesterol 7alpha-hydroxylase. However, compared with their (+/+) controls, the (-/-) mice absorbed more cholesterol (33 vs. 24%) and manifested lower rates of hepatic sterol synthesis (534 vs. 1,019 nmol/h per g). Cholesterol feeding increased hepatic cholesterol levels in the (+/+) animals from 2.7 to 4.4 mg/g and in the (-/-) mice from 2.6 to 8.1 mg/g. Bile acid synthesis increased 70% in both genotypes. Cholestyramine feeding stimulated bile acid synthesis 3.7 fold in both (-/-) and (+/+) mice. We conclude that the virtual loss of HDL-cholesterol from the circulation in apo AI deficiency has no impact on the ability of the hepatocyte to adapt its rate of bile acid synthesis in concert with the amount of cholesterol and bile acid returning to the liver from the small intestine.
Animals↗
Biological and clinical consequences of longitudinal studies in rodents: their possibilities and limitations. An overview.
Rats and mice are used in gerontological research primarily because of their relatively short life spans, ease of handling, and the relatively low costs of production and maintenance under controlled environmental conditions of large number of rodents as compared to larger laboratory animal species. They are being used as models for studying intrinsic aging processes, processes that give rise to diseases associated with aging, and the influence of environmental factors on these processes. Contrary to the situation in man, longitudinal studies in rodents can be conducted under well controlled environmental conditions. It has been shown that multiple pathology, the hallmark of aging in man, also occurs in inbred strains of rodents. Some of these lesions are genetically determined and some of them are randomly distributed amongst members of the same inbred strain. Serial killing experiments are necessary to obtain information on the time of development of these lesions in order to interpret properly the outcome of investigations. Furthermore, it has been shown that a considerable variation can exist in the observed maximum ages of the longest-lived animals in cohorts of rats kept under well controlled conditions. For this reason, caution should be exercised in interpreting data from studies which claim maximum lifespan prolongation.
Aging↗
The role of endogenous opioids in the luteinizing hormone surge in rats: studies with clocinnamox, a long-lasting opioid receptor antagonist.
Endogenous opioid peptides have been demonstrated to regulate luteinizing hormone (LH) secretion in a variety of species. Studies in rodents suggest a role of opioid peptide systems in controlling the timing of the LH surge, which is entrained to the circadian rhythm. The current studies utilize clocinnamox, a novel long-lasting opioid receptor antagonist that is capable of occupying mu-opioid receptors for periods of one week or more, to examine the role of endogenous opioid systems on the LH surge. Administration of clocinnamox [14b-(p-chlorocinamoylamino)-7,8-dihydro-N-cyclopropylmethyl normophineone mesylate]) on the morning of proestrus advanced the LH surge by several hours. Despite the blockade of opioid receptors and analgesia for more than one week, administration of clocinnamox on the evening of diestrus II had no effect on the timing of the LH surge but significantly increased plasma LH levels throughout the day of proestrus. These data suggest that removal of opioid tone is unlikely to be the critical signal controlling the initiation of the LH surge in rodents, although it does appear to be permissive for the surge. Furthermore, the mu-opioid receptor appears to be the receptor involved in the regulation of the LH surge.
Animals↗
Neurobiological mechanisms involved in antidepressant therapies.
Selective serotonin reuptake inhibitors (SSRIs) are effective in alleviating the symptoms of depression. However, clinical improvement is only obtained after several weeks of treatment. SSRIs, when administered acutely to animals, have little effect on synaptic levels of serotonin. This suggests the existence of one or more regulatory mechanisms controlling serotonergic neurotransmission. The firing rate of dorsal raphe serotonergic neurons is under the control of somatodendritic 5-hydroxytryptamine 1A (5-HT1A) autoreceptors, the release of serotonin from nerve terminals is under the control of 5-HT autoreceptors (5-HT1B subtype in rodents, 5-HT1D in other species), whereas the control of the activity of tryptophan hydroxylase, the rate-limiting enzyme of serotonin synthesis, is complex, involving 5-HT1A but possibly other 5-HT receptors including the 5-HT1B/D subtype. During prolonged administration with a SSRI, these three feedback systems become desensitized and their regulatory effects on serotonergic neurotransmission are weakened or lost. This has the effect of allowing the synaptic levels of serotonin to rise with a consequently increased stimulation of one or more types of postsynaptic 5-HT receptor. Thus, it is only after prolonged administration that the pharmacological activity of SSRI is fully expressed in terms of synaptic serotonin levels. This may explain the latency of antidepressant action seen with these drugs in humans. Various other classes of antidepressant therapies (tricyclic antidepressants and monoamine oxidase inhibitor drugs, electroconvulsive therapy) have long-term effects on one or more of the feedback mechanisms such that an increase in synaptic concentrations of serotonin may be a common mechanism of many antidepressant therapies.
Animals↗
Role of the rodent hippocampus in paired-associate learning involving associations between a stimulus and a spatial location.
The ability of rats with control or hippocampal lesions to learn an object-place, odor-place, or object-odor paired-associate task was assessed in a cheeseboard maze apparatus. The data indicate that rats with hippocampal lesions were significantly impaired, compared with controls, in learning both the object-place and the odor-place paired-associate tasks. However, rats with hippocampal lesions learned the object-odor paired-associate task as readily as did controls. The data suggest that the rodent hippocampus is involved in paired-associate learning when a stimulus must be associated with a spatial location. However, the hippocampus is not involved in paired-associate learning when the association does not involve a spatial component.
Animals↗