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Helminth parasites of laboratory mice and rats.

Rodents, as mice and rats are the most common laboratory animals used in research and testing. They are seldom investigated for autochthonous ecto- and endoparasites prior their utilization in the experiments. Helminth parasites can alter the interpretation of final results. Pinworms commonly infecting laboratory rodents include mainly the mice pinworms Syphacia obvelata and Aspiculuris tetraptera, and in rats Syphacia muris. The fact that many laboratory rodent colonies were found to be parasite contaminated suggests a need for eradication and improvment of the quality of laboratory rodents. This review reports the data on the presence of helminth parasites in laboratory rodents colonies, and suggests to pay special attention on controlling the sanitary conditions of animal houses.

Animals↗

Association of genetic variation of the transforming growth factor-alpha gene with cleft lip and palate.

Complex segregation analysis of pedigrees having nonsyndromic cleft lip with or without cleft palate (CL/P) (Chung et al. 1986; Marazita et al. 1986) has shown that a major-locus model best explains the observed recurrence of CL/P in Caucasian families. To identify this major gene, we compared the frequencies of 12 RFLPs at five loci-epidermal growth factor, transforming growth factor-alpha, epidermal growth factor receptor, glucocorticoid receptor, and estrogen receptor-in both a group of 80 subjects with nonsyndromic CL/P and 102 controls. These candidate genes were selected because studies in rodents had suggested their possible involvement in palatogenesis. A significant association was observed between two RFLPs at the transforming-growth-factor-alpha (TGFA) locus and the occurrence of clefting (P = .0047 and P = .0052). This suggests that either the TGFA gene itself or DNA sequences in an adjacent region contribute to the development of a portion of cases of CL/P in humans and provides an opportunity to begin to examine the molecular events underlying lip and palate formation.

Adolescent↗

Bioartificial pancreas in autoimmune nonobese diabetic mice.

The authors wanted to test the long-term effectiveness of immunoisolation in the NOD mouse, an adequate model of Type I diabetes. Recipients were diabetic female NOD mice with sustained plasma glucose levels above 400 mg/100 ml. They were grafted intraperitoneally with permselective hollow fibers seeded with human insulinoma (n = 6), rodent insulinoma (n = 6), or human islets (n = 6). Controls were 15 nontreated diabetic females and 10 nondiabetic male NOD mice implanted with nonseeded macrocapsules. Electron microscopy (rectangular crystalline nucleoids characteristic of B-cells), in vitro release of insulin (during abrupt changes in glucose concentration from 40 to 400 mg/dl and return, M +/- SD insulin levels were 122 +/- 5 uu/ml and 315 +/- 17 at low and high glucose), evidence of binding hormone receptors (VIP and GIP, the binding sites being coupled with adenylyl cyclase stimulation) were used to assess the quality of the transplant. Survival was always prolonged in grafted animals. Taking complete and long-term (less than 3 months) correction of hyperglycemia as the criterion, the success rate was about 50% as observed in streptozotocin rats. Splenocytes isolated from cured and not cured recipients and injected into irradiated nondiabetic male NOD mice were always able to transfer the disease. Our bioartificial pancreas is efficient in preventing the recurrence of the disease in autoimmune diabetes.

Animals↗

Dietary manipulation and exercise in the heat: thermoregulatory and metabolic effects in rats.

To determine the effects of dietary manipulation on the metabolic, physical, and physiological responses to exercise in the heat, adult male rats (n 5 16/group) were food deprived for 72 h followed by ad lib consumption of a high protein (HIPROT) or high carbohydrate (HICARB) diet for 96 h. Each dietary regimen was followed immediately by exercise (9.14 m . min-1) in the heat (35.58C) to hyperthermic exhaustion (TCO approximately 43 8C). Animals consuming the HICARB or HIPROT diet had an increased mean TCO prior to the acute heat/exercise protocol when compared with a control (CONT) group with uninterrupted access to a normal rodent diet; the HICARB rats also manifested a decreased endurance when compared with the CONT group. Plasma levels of urea nitrogen, lactate, and potassium were increased following exercise in the heat in all groups, but greatly exacerbated increments in urea nitrogen occurred in the HIPROT group. Following exercise, significant increments occurred in circulating levels of glucose and insulin in the HIPROT and HICARB groups. Plasma triglycerides were decreased by the exercise/heat regimen but increased by both diets. Thus, these dietary manipulations elicited a variety of metabolic responses which did not markedly alter the physiological and physical effects of work in the heat.

Animals↗

Design and use of an inhalation chamber for air pollution studies in small animals.

Environmental chambers provide a convenient means of studying the toxicology of gases in experimental animals. The specialised equipment needed for these studies is not commercially available. This paper reports on the design, construction and performance of a simple, and inexpensive, inhalation chamber and gas mixing unit for air pollution studies in small laboratory animals. Provision has been made for controlling the mixing of gases, the ventilation rate, the even distribution of gases in the chamber and for the removal of vented gases to prevent the hazard of air pollution in the laboratory animal facility. No significant differences were found between the food and water consumption and body mass gain of a group of rats housed in the chamber for 5 days and a control group housed im similar cages located in a rodent room and managed under conventional laboratory conditions. The chamber fulfills all the requirements for an animal inhalation system.

Air Pollutants↗

Hantavirus pulmonary syndrome -- Chile, 1997.

Hantavirus pulmonary syndrome (HPS) was first recognized in Chile in October 1995; through July 1997, nine cases had been identified in the country. However, during August 1-October 8, 1997, a total of 12 persons with HPS, including two family clusters, were recognized. A collaborative investigation is under way to determine the magnitude of this outbreak, the associated rodent reservoir for hantaviruses, and the major risk factors for human infection. This report summarizes the preliminary results of the ongoing investigation, which suggest that the outbreak among humans is paralleled by exceptionally high densities of potential rodent reservoir species.

Adolescent↗

Effect of thromboxane synthetase inhibitor on non-heart-beating donors in rat orthotopic liver transplantation.

BACKGROUND: The use of non-heart-beating donors could relieve donor organ shortage provided that the outcome of the recipients is not jeopardized. METHODS: In this study we evaluated the effect of thromboxane synthetase inhibitor (OKY-046) on non-heart-beating donors in orthotopic liver transplantation in rodents. OKY-046 (OKY group, n = 8) or vehicle (control group, n = 8) was given to the donor animals for 60 minutes before the induction of 30 minutes of warm ischemia to the liver before transplantation and survival, and several parameters were compared between the two groups. RESULTS: All recipients in the control group died within 2 days, whereas 67% of those of the OKY group had a 2-day survival and 44% had a 2-week survival (p < 0.01). Bile output from the allograft for 2 hours after reperfusion was significantly larger in the OKY group at all time points (p < 0.05). Furthermore, serum transaminase levels 10 minutes after reperfusion were significantly lower in the OKY group (p < 0.05), although those 120 minutes after reperfusion were comparable between the two groups. The thromboxane B2 level in liver tissue 10 and 120 minutes after reperfusion was significantly lower in the OKY group compared with the control group (p < 0.02 and p < 0.05, respectively). CONCLUSIONS: These results indicate that OKY-046 given to the donor before the induction of warm ischemia could ameliorate ischemia/reperfusion injury of the hepatic allograft by reducing thromboxane A2 production after reperfusion.

Alanine Transaminase↗

[Lipid metabolism related nuclear receptor--the structure, function, expression and classification of peroxisome proliferation-activated receptor (PPAR)].

Peroxisome proliferator-activated receptors (PPARs) belongs to the nuclear hormone receptor superfamily. So far three different subtypes of PPAR (alpha, gamma, and delta (beta)) have been identified in amphibians, chicken, rodents and man. These receptors are transcription factors that control the beta-oxidation and transport pathways of fatty acids and adipocyte differentiation containing fatty acid synthesis under the modification of PPAR activation with CBP and its analogs. Thus, PPARs play an important role in lipid metabolism. Furthermore, altered fatty acid levels are associated with obesity, diabetes, hypertension and atherosclerosis, so PPARs may serve as molecular sensors in these metabolic disorders.

Activating Transcription Factor 2↗

Glutathione elevation and its protective role in acrolein-induced protein damage in synaptosomal membranes: relevance to brain lipid peroxidation in neurodegenerative disease.

Oxidative stress may be a hallmark of several neurodegenerative disorders, including Alzheimer's disease (AD) Huntington's, and Parkinson's diseases as well as amyotrophic lateral sclerosis. Acrolein is a highly reactive product of lipid peroxidation that is elevated in the brains of persons with AD. This alkenal potentially can react with proteins by Michael addition to alter their structure and function. In the present study, we used electron paramagnetic resonance in conjunction with a protein-specific spin label to monitor synaptosomal membrane protein conformational alterations induced by acrolein. A dose-dependent increased conformational alteration was observed. Consistent with this finding, protein carbonyl levels from protein-bound acrolein were significantly elevated. However, pretreatment of synaptosomes with glutathione ethyl ester (GEE) significantly ameliorated both the conformational alterations and protein carbonyls induced by acrolein. Based on this success, we tested the hypothesis that elevated levels of endogenous glutathione (GSH) would offer protection against acrolein-induced oxidative stress. In-vivo elevation of GSH (215% over control, P<0.04) was produced by i.p. injection of N-acetylcysteine (NAC), a known precursor of GSH. Synaptosomes were treated with vehicle or 2 nM acrolein, the level of this alkenal found in AD brain. In contrast to synaptosomes from control animals, which had significantly increased protein carbonyl levels following addition of 2 nM acrolein, synaptosomes that were isolated from NAC-treated rodents and treated with 2 nM acrolein showed no increased carbonyl levels compared to untreated controls. These results demonstrate protection by increased in-vivo GSH levels against acrolein-induced oxidative stress at levels found in AD brain and are consistent with the notion that methods to increase endogenous GSH levels in neurodegenerative diseases associated with oxidative stress may be promising.

Acetylcysteine↗

Bayesian methods for a three-state model for rodent carcinogenicity studies.

The objective of a chronic rodent bioassay is to assess the impact of a chemical compound on the development of tumors. However, most tumor types are not observable prior to necropsy, making direct estimation of the tumor incidence rate problematic. In such cases, estimation can proceed only if the study incorporates multiple interim sacrifices or we make use of simplified parametric or nonparametric models. In addition, it is widely accepted that other factors, such as weight, can be related to both dose level and tumor onset, confounding the association of interest. However, there is not typically enough information in the current study to assess such effects. The addition of historical data can help alleviate this problem. In this article, we propose a novel Bayesian semiparametric model for the analysis of data from rodent carcinogenicity studies. We develop informative prior distributions for covariate effects through the use of historical control data and outline a Gibbs sampling scheme. We implement the model by analyzing data from a National Toxicology Program chronic rodent bioassay.

Animals↗

Isopentenoid synthesis in eukaryotic cells. An initiating role for post-translational control of 3-hydroxy-3-methylglutaryl coenzyme A reductase.

Using insect (Drosophila) and rodent mammalian cell cultures we demonstrate that acute mevalonate-mediated suppression of 3-hydroxy-3-methylglutaryl coenzyme A was initiated in the absence of protein synthesis. In addition, insect and mammalian cells depleted (1 h) of putative regulatory post-isopentenyl-1-pyrophosphate metabolites by incubation with an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A synthase (L-659,699) accumulated 3-hydroxy-3-methylglutaryl coenzyme A reductase enzyme units. This accumulation resulted primarily from a decrease in the loss of 3-hydroxy-3-methylglutaryl coenzyme A reductase enzyme units rather than from an increase in enzyme synthesis. These observations suggest that the initial phase of mevalonate-mediated suppression of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity was governed primarily by post-translational processes. An unknown rapidly turning over post-isopentenyl-1-pyrophosphate metabolite(s) is proposed as the agonist for these post-translational processes.

Cell Line↗

Interferon regulatory factor-1 immunoreactivity in neurons and inflammatory cells following ischemic stroke in rodents and humans.

Interferon regulatory factor-1 (IRF-1), a transcription factor that controls the expression of genes related to inflammation and injury, may be involved in the mechanisms of cerebral ischemia. In this study, we used immunohistochemistry to determine whether IRF-1 protein is up-regulated after cerebral ischemia, and to define the identity of the cells that express IRF-1 in the postischemic brain. In mice, IRF-1 immunoreactivity was present in intravascular neutrophils 24 h after middle cerebral artery occlusion. At 96 h, immunoreactivity was observed in neutrophils infiltrating the ischemic tissue and in neurons at the outer border of the ischemic territory. IRF-1 immunoreactivity was also found in neurons and inflammatory cells in the brain of patients who died 1-2 days after ischemic stroke. The neuronal expression of IRF-1, in conjunction with the finding that IRF-1 deletion is beneficial to the post-ischemic brain, suggests that expression of IRF-1-dependent genes in neurons plays a role in ischemic neuronal death.

Aged↗

Selective effects of citalopram in a mouse model of stress-induced anhedonia with a control for chronic stress.

A stress-induced decrease in sucrose preference in rodents is regarded as an analog of anhedonia, a key symptom of depression. We investigated the effects of citalopram, administrated via drinking water (15 mg/kg/day), in a mouse model of stress-induced anhedonia. In this model, chronic stress induces anhedonia in a subset of C57BL/6N mice, while the remaining animals do not show a hedonic deficit or other depressive-like behaviors, although they are exposed to the same stressors as the anhedonic mice. Pre-stress and post-stress treatment with citalopram counteracted the development and maintenance of anhedonia and rescued normal floating in the forced swim test, demonstrating an antidepressant-like action. During the post-stress treatment, citalopram selectively increased sucrose preference and intake on the fourth week of treatment in anhedonic mice without affecting non-anhedonic animals. Citalopram also decreased elevated water consumption in the anhedonic group. Citalopram, administered 1 week before and during a 4-week stress procedure, decreased the percentage of anhedonic mice and reduced the increase of water intake in stressed mice. This study suggests that our chronic stress paradigm can serve as a model of anhedonia, in which antidepressant treatment is selectively effective in animals with a hedonic deficit.

Animals↗

Proliferating cell nuclear antigen: a marker for hepatocellular proliferation in rodents.

Two different markers for quantitating cell proliferation were evaluated in livers of control and chemically treated mice and rats. Proliferating cell nuclear antigen (PCNA), an endogenous cell replication marker, and bromodeoxyuridine (BrdU), an exogenously administered DNA precursor label, were detected in formalin-fixed, paraffin-embedded tissues using immunohistochemical techniques. The percentage of cells in S phase (labeling indexes, LI) evaluated as PCNA- or BrdU-positive hepatocellular nuclei was compared in recut tissue sections from animals given BrdU by a single IP injection 2 hr before killing the animals. Ten-week-old male B6C3F1 mice and F344 rats were exposed to known mitogenic hepatocarcinogens, Wy-14,643 (WY) in the diet at 0.1% for 2 days or 1,4-dichlorobenzene (DCB) in corn oil by gavage for 2 days (600 mg/kg/day in mice; 300 mg/kg/day in rats). In mice, PCNA and BrdU hepatocyte LI were similar in control, WY-treated, and DCB-treated animals. In rats, PCNA and BrdU gave similar LI in controls and Wy-treated animals. Although PCNA LI was statistically lower than BrdU LI in DCB-treated rats, both PCNA and BrdU LI for DCB-treated rats was increased over LI in control rats. Different patterns of PCNA immunohistochemical staining, interpreted to represent different subpopulations of cells at various phases of the cell cycle, were quantitated using PCNA immunohistochemistry. The proliferating index (PI), defined as the percentage of cells in the cell cycle (G1 + S + G2 + M), was more sensitive than the LI (S phase only) in detecting a chemically induced cell proliferative response.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Decreased cytotoxic activity of natural killer cells in kidney allograft recipients treated with human HLA-derived peptide.

Peptides derived from a conserved region (aa 75-84) of HLA class I, overlapping the supertypic HLA-BW4/BW6 antigen region, have been shown to exhibit nonallele restricted immunosuppressive properties in rats and mice, prolonging survival of major histocompatibility complex-mismatched allografts. Furthermore, HLA-B7 peptides inhibit alloreactive cytotoxic cells, and both HLA-B7 and HLA-B2702 peptides inhibit natural killer (NK) cytotoxicity in vivo. In this article, we report on a randomized, controlled study of the safety and pharmacokinetics of HLA-B2702-derived peptide in human recipients of a first kidney allograft. Escalating doses of HLA-B2702 were compared with doses of placebo controls. No toxicity and no immunization against the peptide were noted. Although the study was not designed as an efficacy trial, patients who received the high-dose protocol (7 mg/kg) did experience more rejection episodes, but this was not statistically significant when compared with control patients. Interestingly, in human recipients, as previously observed in rodents, administration of the peptide was associated with a statistically significant decrease in the cytotoxicity of NK cells against K562 targets (P<0.001). As these peptides correspond to a region of the HLA class I molecule that interacts with the newly described NK receptors for class I, their mode of action through interaction with such receptors is discussed. As a peptide of the same sequence from HLA-B7 blocks both NK and alloreactive T cell cytotoxicity, it is possible that, in humans too, both types of cytotoxic cells are affected by this peptide. The biological significance of these observations should be confirmed in future controlled studies with a larger patient population.

Acute Disease↗

In vitro demyelination by serum antibody from patients with Guillain-Barré syndrome requires terminal complement complexes.

Serum from 7 patients who had acute-phase Guillain-Barré syndrome with high anti-peripheral nerve myelin antibody activity (54 to 210 units/ml) was compared with serum from 3 patients in the recovery phase (0 to 17 units/ml) and serum from 7 disease control subjects (0 to 24 units/ml) and 7 normal control subjects (0 to 7 units/ml) for its ability to demyelinate rodent dorsal root ganglion cultures. The demyelinating capacity of each serum was quantitated by counting the percent of damaged internodal segments in each of four cultures. All sera from patients in the acute phase GBS caused 50 to 78% demyelination, in contrast with 6 to 19% by the sera from all 3 patients in the recovery phase and all other control subjects. The degree of demyelination correlated with anti-peripheral nerve myelin antibody activity of the sera and demyelination was complement-dependent. Further, cultures were treated with an immunoglobulin M (IgM) fraction of an acute-phase Guillain-Barré syndrome plasma plus normal human serum depleted of complement component C7. Only those cultures treated with IgM and C7-depleted human serum reconstituted with purified C7 resulted in 50.8% demyelination, which was significantly greater than the 14.2 to 16.2% demyelination observed in the presence of heat-inactivated, C7-depleted human serum plus purified C7 or in the absence of C7 or antibody. In summary, our work suggests that anti-peripheral nerve myelin antibody in Guillain-Barré syndrome mediated complement dependent-demyelination of rodent dorsal root ganglion cultures. Further, this in vitro demyelination required generation of activation complexes of the terminal complement cascade.

Acute Disease↗

Genotoxicity biomonitoring in coal regions using wild rodent Ctenomys torquatus by Comet assay and micronucleus test.

Coal is a mixture of a variety of chemicals, especially hydrocarbons, which may give rise to polycyclic aromatic hydrocarbons (PAH). Many PAH compounds produce mutagenic and carcinogenic effects. The quality of mineral coal in Rio Grande do Sul (RS) is low and it is typically obtained by stripping operations; it represents approximately 87% of the Brazil reserves. This report concerns the application of the Comet assay to Ctenomys torquatus to detect the effects of coal, comparing the results with a micronucleus (MN) assay, both using peripheral blood. This study was performed over a 2-year period in an attempt to evaluate seasonal patterns. The wild rodent is fossorial, and its geographic distribution in RS coincides with the distribution of coal reserves. Three localitions were studied: two coal fields, Butiá (in a strip coal mine region) and Candiota (near a strip coal mine), and one control region, Pelotas (no coal). At the end of 2 years, 240 rodents had been analyzed. Our results showed that coal and derivatives induced DNA and chromosomal lesions in rodent cells that were demonstrated by Comet and MN assays. These tests also demonstrated quantitative differences between field exposures (Candiota > Butiá). The Comet assay was more sensitive and also showed a direct relationship between age and damage, and an inverse relationship between temperature and damage index.

Animals↗

PYRUVATE METABOLISM AND CONTROL: FACTORS AFFECTING PYRUVIC CARBOXYLASE ACTIVITY.

Pyruvic carboxylase activated by acetyl coenzyme A is highly active in the mitochondria of rodent liver, and its activity is increased in fasting and alloxan diabetes. In conjunction with acyl carboxylase activated by di- and tricarboxylic acid, it forms a reciprocating control network. Analog models of similar networks tend to correct for perturbations, stabilizing the overall system.

Animals↗