Laboratory tests of dimethoate for systemic control of chigger (Acarina: trombiculidae) population on rodents.
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Animals↗
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Results for “Rodent Control”
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Brain temperature measurement and regulation in awake and freely moving rodents.
Temperature measurement and control are essential in most ischemia experiments. Hypothermia lessens ischemic brain injury whereas hyperthermia exacerbates it. A substantial number of ischemia studies rely solely on rectal temperature measurements during the insult. However, rectal temperature may not accurately reflect brain temperature especially during global ischemia. Furthermore, postischemic temperature changes are often inadequately monitored. Delayed cooling reduces injury, whereas delayed hyperthermia aggravates it. This review summarizes our experiences with core and brain telemetry probes to continually measure temperature in various ischemia models. Furthermore, we discuss methods to simultaneously measure and regulate temperature in the freely moving postischemic rodent, and the need for such control in ischemia research.
Animals↗
Tick-borne relapsing fever: an interstate outbreak originating at Grand Canyon National Park.
During the 1973 summer season, 27 employees and 35 overnight guests at the North Rim, Grand Canyon National Park, Arizona, acquired febrile illnesses compatibel with relapsing fever. Sixteen cases were confirmed by finding Borrelia spirochetes in peripheral blood smears or inoculated Swiss mice. Retrospective surveys of 278 employees and 7247 guests at the park revealed that acquisition of illness was significantly associated with the persons sleeping in rustic log cabins and acquiring bites of "unknown" insects. From rodent nesting materials found in the walls and attics of cabins where cases had occurred, infective Ornithodoros hermsi ticks were recovered. Exceptional activity of ticks in human populations appeared to have resulted from a decreased population of the ticks' usual rodent hosts. Vector control activities consisted of spraying the cabins with residual insecticide, removing nesting materials, and "rodent proofing." This outbreak, the largest yet identified in North America, extends the known range of a principal vector and establishes the North Rim as an endemic source of tick-borne relapsing fever.
Adult↗
An automated system for animal exposure to nitrogen dioxide.
We have designed an automated system for controlled exposure of rodents to nitrogen dioxide (NO2). The system consists of 1) two stainless-steel exposure chambers (3.96 m3), for control and treated animals, in which temperature, humidity, and air changes are consistent with current guidelines for rodent housing; 2) a cylinder containing 1% NO2 in N2; 3) a detector connected with a personal computer system that monitors the NO2 concentration, and regulates the NO2 influx, using a closed-loop feedback; and 4) a fan system to distribute the gas uniformly within the chambers. In a typical experiment rats were exposed to 15 ppm of NO2, and changes in the differential count of polymorphonuclear leukocytes, macrophages, and lymphocytes in bronchoalveolar lavage fluid were investigated.
Animals↗
DETECTION OF AN ENZOOTIC PLAGUE FOCUS BY SEROLOGICAL METHODS.
Complement-fixation and haemagglutination tests, utilizing a highly purified, specific Fraction 1 antigen of Pasteurella pestis, have been employed to detect specific plague antibody in the sera of rodents resident in a sylvatic plague focus. The data show that while the isolation of P. pestis is seasonal and rather rare, antibodies can be detected for long periods of time and with great frequency in rodents surviving infection. The authors recommend that serological methods be incorporated into epidemiological surveys and control programmes involving rodent plague.
Animals↗
Control of early development of the pancreas in rodents and humans: implications of signals from the mesenchyme.
During the last few years, progress has been made in the control of pancreatic development. Many transcription factors have been described in the pancreas and a genetic approach has been used to define their role in pancreatic development. Pancreatic development depends on mesodermic signals, with the initial steps controlled by signals from the notochord that is in close contact with the dorsal endoderm of the gut fated to become pancreas. Later signals from the mesenchyme that surrounds the embryonic pancreatic epithelium regulate the proliferation of immature pancreatic epithelial cells and their differentiation into endocrine or exocrine tissue. This review discusses recent data on the role the signals from the mesenchyme have in the development of the pancreas in rodents and humans.
Animals↗
Damage to the liver, kidney, and testis with reference to burden of heavy metals in yellow-necked mice from areas around steelworks and zinc smelters in Poland.
The influence of the steelworks in Warsaw and Krakow as well as the zinc smelters in Bukowno and Miasteczko Slaskie on lead, cadmium, zinc and iron concentrations and the structure of selected tissues of yellow-necked mice were analysed. The Borecka Forest was chosen as a control area. The highest concentrations of lead, 172.36 g/g dry weight, and cadmium, 23.58 g/g, were detected in the femurs and kidneys, respectively, of rodents caught in Bukowno. Zinc and iron concentrations ranged over physiological values. No histopathological changes were observed in analysed tissues of all rodents in the control area. Damage occurred in the liver and kidneys of animals from all other sites and in the testes of rodents from Bukowno. Decreased glycogen content, interstitial fibrosis, and increased number of pyknotic nuclei as well as necrosis were seen in hepatocytes. In the kidneys hyperplasia of the tubules, atrophy of glomeruli, interstitial fibrosis and necrosis were observed. Degenerate cells were present in the lumen of seminiferous tubules of animals from the Bukowno area. Even relatively low concentrations of lead and cadmium, like those found in the liver and kidneys of rodents from the neighbourhood of the steelworks, caused histopathological changes.
Animals↗
Control of reproductive and energetic status by environmental cues in a desert rodent, Shaw's jird.
The photoperiod is the controller of reproductive cycles in temperate climates for most mammalian species. Several nonphotoperiodic cues appear to control reproductive status at lower latitudes. We tested the roles of the photoperiod or water availability on the reproductive status of the desert-dwelling Shaw's jird (Meriones shawi) trapped from a moderately temperate climate (approximately 30 degrees N in Egypt). Males and females were transported to the laboratory and, in Experiment 1, were housed in either the longest (LDs) or shortest (SDs) photoperiod that occurs naturally at this latitude (14 h light, 10 h dark, and 10 h light, 14 h dark, respectively). In Experiment 2, LD-housed male jirds were subjected to a water availability schedule that inhibits reproductive status in a closely related species (Meriones unguiculatus). Specifically, one group had no free water, but had lettuce available once a week for 24 h (control jirds received free water for 10-60 min/day). Neither photoperiod nor free-water deprivation affected reproductive status of male or female jirds. That is, neither testes mass nor spermatogenetic activity (males), nor uterine mass nor folliculogenesis (females) were affected by either condition. In addition, photoperiod did not affect body or white adipose tissue (WAT) masses, although SDs decreased carcass lipid in males. Free-water deprivation decreased body and WAT pad masses, and all carcass components. Collectively, these results suggest that changes in day length or water availability alone do not affect reproductive status in Shaw's jird.
Adaptation, Physiological↗
Paracrine factors in adult rat testis gonadotrophin control of opioids and LHRH like peptide.
A paracrine regulation involves agents which are produced by one cell type and act on an other one within an organ. In rodent testis, local control mechanisms modulate the actions of the gonadotrophins according to local requirements. Two groups of peptides-opioids and testicular LHRH are defined as paracrine factors and in vivo they are both modified by HCG. In vitro, after HCG exposure, we first localized an opioid like material in Sertoli cells cytoplasma by immunohistochemistry. This material is detected in freeze dried homologous culture media using a dot immunobinding technique. With a longer HCG exposure, an LHRH like material is then visualized in the basal compartment of the Sertoli cells and it is detected in freeze dried homologous culture media by the same technical procedure than for opioid material. By adding synthetic enkephalins to culture medium, we obtain the same results as with the endogenous opioid material, excreted after HCG addition. If naloxone a potent opiate antagonist, is added to the culture medium previously to HCG or enkephalins, the Sertoli cells cytoplasma are no more immunoreactives with the anti-enkephalin serum and no LHRH material is neither visualized by immunohistochemical technique neither detected in culture media. We conclude that testicular opioids, synthetized by the Leydig cells and which have specific Sertoli cells receptors are one Leydig-Sertoli paracrine communication factor. One way of response to their receptor fixation is the synthesis and excretion by Sertoli cells of testicular LHRH. This one is known to act on Leydig cells via specific receptors and it is one Sertoli-Leydig cells paracrine communication factor.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
The mouse bioassay for the detection of estrogenic activity in rodent diets: III. Stimulation of uterine weight by dextrose, sucrose and corn starch.
We have shown previously that mice fed the American Institute of Nutrition (AIN-76A) purified diet experience a significant increase in uterine:body weight (U:BW) ratios when compared to the U:BW ratios of mice fed a closed formula natural ingredient diet (Certified Rodent Chow #5002) for 7 days. The AIN-76A purified diet contains 5% corn oil and 65% carbohydrates with 50% of the carbohydrates coming from sucrose or dextrose and 15% from corn starch. The objective of this study was to determine whether the fat and carbohydrate content contributed to the unexpected uterine growth promoting activity observed in mice fed the AIN-76A diet. Estrogen bioassays were performed using CD-1 mice weaned at 15 days of age and assigned randomly to the negative control diet (Certified Rodent Chow #5002) or to the positive control diet (#5002) containing 4 or 6 ppb DES for comparison or to the test diets. The test diets were prepared by adding sucrose, dextrose, corn starch, corn oil or soybean oil to the #5002 negative control diet at 10% w/w concentration. Uterine:BW ratios were determined at 7 days post-feeding. The uterine weights and the U:BW ratios of mice fed the test diets containing dextrose, corn starch, or corn oil, were increased significantly (P less than 0.05) over those of mice fed the negative control diet. The uterine weights and U:BW ratios of mice fed the test diets containing sucrose or soybean oil also were increased over those of mice fed the negative control diet. These increases in uterine weights and U:BW ratios were similar to the increases in uterine weights and U:BW ratios of mice fed the positive control diet containing 4 ppb DES. It was concluded that the fats and carbohydrates caused preferential increases in uterine weights and in U:BW ratios and may account for the estrogen-like uterine growth promoting activity observed in mice fed the AIN-76A purified diet.
Animal Feed↗
Development of whisker-related patterns in marsupials: factors controlling timing.
In mature rodents, whisker-related patterns are known to be present in three levels of the brain: the brainstem trigeminal nuclei, the ventrobasal thalamus and the somatosensory cortex. These patterns have been demonstrated using neuroanatomical tracing techniques, histological and histochemical staining methods and electrophysiological recordings. The development and topography of these patterns are dependent on an intact periphery. But what governs when patterns form at the three levels? Possibilities include a controlling signal from the periphery or local mechanisms at each site, such as the arrival of afferent inputs or the maturation of target tissue. In this review, we report on the maturation of the whisker pathway in a marsupial, the wallaby, where the slow tempo of development is a feature. At each level, afferent fibres grow into the region of termination many weeks before the whisker-related pattern emerges. The results suggest that the maturity of the target tissue as well as signals from the periphery combine to trigger pattern formation at each level of the pathway.
Animals↗
Regulation of a heterologous glucose transporter promoter in chicken embryo fibroblasts.
GLUT1 is a glucose transporter responsible for increased cellular glucose uptake upon oncogenic transformation or mitogenic stimulation. This is associated with transcriptional activation of the GLUT1 gene. Three regions in the mouse GLUT1 gene mediate this regulation (the promoter and two enhancers). In contrast, chicken GLUT1 transcription is completely uninducible, suggesting either avian signal transduction events are different or the chicken GLUT1 gene lacks these transcriptional control elements. To distinguish between these possibilities, reporter plasmids containing mouse GLUT1 control elements in rodent and avian fibroblasts were compared. These elements function within chicken cells, suggesting that signaling pathways are similar to mouse cells but that the avian GLUT1 gene lacks the control elements necessary to respond to them.
3T3 Cells↗
Exercise capacity and cardiac function of rats with drug-induced cardiac enlargement.
A study was undertaken to determine if sustained administration of isoproterenol (ISO) alters biochemical and functional properties of hearts and the submaximal and maximal exercise capacity of rodents. Compared with sham-treated controls of the same age, sex, and body weight, 4 wk of ISO (0.2--0.4 mg/kg sc) produced an approximate 30% increase in combined ventricle wet weight (P less than 0.001). Respiratory capacity of homogenates, total muscle protein concentration, and actomyosin and myofibril ATPase of heart muscle of the ISO-treated group were the same as in the control group. Various cardiac function parameters in situ, obtained under control conditions and in response to tyramine-induced norepinephrine release, were similar for the two groups. ISO-treated rats had slightly greater endurance for running submaximally on a treadmill than the control rats (P less than 0.10), but their maximal capacity to utilize oxygen (VO2max) was not different from controls. These findings suggest that rodent hearts moderately enlarged by relatively low doses of isoproterenol possess normal metabolic and functional capacity. However, this cardiac enlargement had no apparent effect on maximal exercise performance of the whole animal.
Actomyosin↗
Experimental filariasis of Dipetalonema dessetae in Proechimys oris: 3. Effects of parasitism on the pharmacokinetics of diethylcarbamazine.
The pharmacokinetic parameters of diethylcarbamazine were compared in the plasma and peritoneal fluid of 5 non-infected rodents. In the filarial animals, the absorption rate constant and the elimination rate constant were significantly increased. The peak plasma concentration was twofold higher in the infested rodents than the control animals, and this may account for the rapid action of diethylcarbamazine on blood-circulating microfilariae. The area under the curve was unchanged. Total clearance is slightly increased in filarial rodents. These data are explained by an important reduction of renal clearance combined with a moderate increase of extra renal clearance. High levels of diethylcarbamazine in peritoneal fluid, resulting from the excellent diffusion of the drug in filarial animals explains the activity on adult worms. But the parasitism does not affect the mechanism of distribution of the drug between plasma and peritoneal liquid.
Animals↗
Effect of pyridoxine deficiency on phospholipid methylation in rat liver microsomes.
The effect of altered methionine metabolism during pyridoxine deficiency on the activity of phosphatidylethanolamine methyltransferase (EC 2.1.1.17) and the levels of phosphatidylethanolamine (PE) and phosphatidylcholine (PC) has been evaluated in rat liver microsomes. Animals fed a pyridoxine-deficient diet for 7 wk displayed a fivefold increase in the hepatic tissue level of S-adenosylhomocysteine when compared to either control or pair-fed animal counterparts. When PE methyltransferase was assayed in vitro, a significant increase in specific activity was observed using enzyme preparations from either pair-fed or pyridoxine-deficient rats. On the other hand, phospholipid levels did not conform to the measured enzyme activity. The level of PC in microsomes from either pyridoxine-deficient or pair-fed animal groups was significantly lower than that determined for the control group of rodents. However, the level of PC was noticeably lower in microsomes from pyridoxine-deficient animals than that from pair-fed animals, which received 45% of the feed intake of the control animals. In addition, the level of PE in microsomes from pair-fed and pyridoxine-deficient animals was significantly higher than that analyzed from the control animals, further confirming decreased methylation of substrate to product. It is concluded that pyridoxine deficiency may alter the methylation of phospholipid in the endoplasmic reticulum above and beyond that produced by feed restriction alone.
Adenosine↗
Effects of an engineered human anti-TNF-alpha antibody (CDP571) on insulin sensitivity and glycemic control in patients with NIDDM.
Inhibition of tumor necrosis factor (TNF)-alpha action has recently been shown to reverse insulin resistance dramatically and to improve glycemic control in obese rodents. This double-blind study was designed to assess the effects of a recombinant-engineered human TNF-alpha-neutralizing antibody (CDP571) on glucose homeostasis in obese NIDDM patients. Glycemic control and insulin sensitivity were monitored in 21 NIDDM subjects for a 2-week run-in and then for 6 weeks after treatment in a randomized fashion with a single intravenous dose of either CDP571 (5 mg/kg) or an equivalent volume of normal saline. The prolonged half-life of the antibody ensured adequate plasma levels as measured throughout the study. Concentrations of fasting glucose (CDP571: 10.0 +/- 0.8, 10.1 +/- 0.8, 10.0 +/- 1.0; placebo: 8.5 +/- 0.6, 8.1 +/- 0.5, 8.7 +/- 0.8 mmol/l at baseline, day 1, and week 4, respectively), fasting serum insulin (CDP571: 21.2 +/- 2.8, 21.0 +/- 2.8, 24.8 +/- 3.3; placebo: 19.0 +/- 2.8, 20.8 +/- 2.9, 17.5 +/- 2.2 pmol/l, respectively), and C-peptide remained unaffected by the type of treatment throughout the study. The percentage rate of glucose clearance per minute (KITT) during intravenous insulin sensitivity tests was identical in the CDP571 and placebo groups at baseline and also at 1 and 4 weeks after treatment (mean +/- SE; CDP571: 1.33 +/- 0.21, 1.44 +/- 0.25, 1.26 +/- 0.18; placebo: 1.38 +/- 0.15, 1.47 +/- 0.20, 1.52 +/- 0.20; P = 0.85, 0.93, and 0.36, respectively). TNF-alpha neutralization over a period of 4 weeks had no effect on insulin sensitivity in obese NIDDM subjects.
Antibodies↗
Asexual blood stages of malaria modulate gametocyte infectivity to the mosquito vector--possible implications for control strategies.
In the rodent malarial parasite Plasmodium berghei sexual parasites are produced in a single major wave with maximal numbers between day 7 and day 16. Irrespective of their time of appearance during infection these sexual parasites are equally fertile in vitro. In contrast, in vivo infectivity to the mosquito is maximal at day 3-5 when gametocyte numbers are only 9% of the peak levels seen between days 7 and 16. Up to 96% of natural potential infectivity of gametocytes for the mosquito is therefore suppressed. The suppression is humoral, reversible and correlates with the appearance of an effective host response to the initial rapid increase in asexual parasitaemia. These data are consistent with published evidence which indicates that a reduction in parasitaemia may cause an increase in infectivity of gametocytes to the mosquito vector. Therefore the impact of strategies aiming to control asexual parasites is re-examined. Inefficient strategies might be predicted to increase and not suppress malaria transmission.
Animals↗
Flea ectoparasites of commensal rodents in Shebin El Kom, Menoufia Governorate, Egypt.
Rodents population are widely distributed in some Egyptian Governorates, particularly those in the Nile Delta. Generally speaking, rodents particularly those living in close association with man, play a major role in human health, welfare and economy. Besides, their arthropod ectoparasites are important vectors of pathogenic agents as well as they themselves are causative agents of many allergic disorders. No doubt, the increase in rodent population is followed by an increase in many zoonotic diseases. In Shebin El Kom city, the capital of Menoufia Governorate three commensal rodents were identified. They were Mus musculus (house mouse), Rattus rattus (black rat) and Rattus norvegicus (Norway rat). The maximal rat index was in Autumn (0.69) and minimal was in Winter (0.2). Five species of fleas were collected from the rodents. They were Xenopsylla cheopis (57.7%), Xenopsylla ramesis. (12.7%), Pulex irritans (12.7%), Leptopsylla segnis (11.3%) and Ctenocephalides felis (5.6%). The maximal flea index was in Spring (1.02) and the minimal was in Winter (zero) The highly infested rodent species was R. rattus (0.65/rat), R. norvegicus (0.62/rat) and the lowest was M. musculus (0.45/mouse). The overall flea index was 0.59. The role of fleas in disease transmission was included. No doubt, to carry out feasible control measures against rodents and their ectoparasites complete understanding of their bionomics must be well studied.
Animals↗